WO2022032460A1 - 一种锂电池的析锂检测方法及装置 - Google Patents
一种锂电池的析锂检测方法及装置 Download PDFInfo
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- B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
- B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
- B60L58/16—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to battery ageing, e.g. to the number of charging cycles or the state of health [SoH]
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- B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
- B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
- B60L3/0046—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to electric energy storage systems, e.g. batteries or capacitors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
- B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
- B60L58/12—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to state of charge [SoC]
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/54—Drive Train control parameters related to batteries
- B60L2240/545—Temperature
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/54—Drive Train control parameters related to batteries
- B60L2240/547—Voltage
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2260/00—Operating Modes
- B60L2260/40—Control modes
- B60L2260/44—Control modes by parameter estimation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/374—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC] with means for correcting the measurement for temperature or ageing
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2220/00—Batteries for particular applications
- H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
Definitions
- the present application relates to the technical field of batteries, which can be applied to new energy vehicles, electric vehicles, smart vehicles, and connected vehicles, and in particular, to a method and device for detecting lithium precipitation in lithium batteries.
- Lithium batteries are widely used in electronic devices such as mobile phones, tablet computers, portable devices, and various electric vehicles such as electric vehicles and electric motorcycles due to their advantages of low pollution, high energy density, long cycle life and low self-discharge rate. , become an indispensable part of these equipment or vehicles. Therefore, the safety of lithium batteries has attracted more and more attention. As an abnormal phenomenon of lithium batteries during charging, lithium precipitation is one of the hot issues that people pay attention to in recent years.
- lithium ions are deintercalated from the positive electrode and intercalated into the negative electrode.
- these lithium ions will be precipitated on the surface of the negative electrode to form metallic lithium, which is called lithium precipitation.
- the conditions for the occurrence of lithium precipitation can be divided into two types: internal factors and external factors. Internal factors usually include that the potential of the negative electrode to lithium is less than 0, which results in that the lithium ions are no longer fully embedded in the negative electrode, but some are embedded in the negative electrode, and some are precipitated in the lithium metal state. External factors typically include low temperature, high state of charge (SOC), and high rate charging.
- SOC state of charge
- the low temperature will cause the diffusion power of lithium ions to slow down, and the potential of the negative electrode to lithium in the high charge state is relatively low, so the low temperature and high charge state are not conducive to the insertion of lithium ions into the negative electrode; high-rate charging will generate a strong electric field to push a large amount of lithium Ions are deintercalated from the positive electrode and intercalated into the negative electrode.
- the number of lithium ions deintercalated is greater than the number of lithium ions that the negative electrode can receive, lithium precipitation occurs.
- the occurrence and accumulation of lithium precipitation will reduce the coulombic efficiency, resulting in a reduction in the capacity of lithium batteries, and the precipitated lithium metal can easily cause anode expansion and particle rupture, exposing more fresh anode interfaces to the electrolyte to form new solid electrolyte interfaces. interface, SEI) film, resulting in an increase in impedance.
- the continuous growth of the precipitated lithium metal will lead to the formation of lithium dendrites, which in turn induces an internal short circuit, which brings safety risks.
- the precipitated lithium metal will also react slowly with the electrolyte, greatly reducing the onset temperature of thermal runaway. Therefore, there is a demand for lithium evolution detection of lithium batteries.
- the lithium evolution detection method is: in the process of charging the lithium battery, monitoring the charging voltage and state of charge of the lithium battery, the charging voltage is used as the first voltage; In the corresponding relationship between the set open-circuit voltage and the state of charge, the voltage value corresponding to the current state of charge is obtained as the second voltage; according to the difference between the first voltage and the second voltage (that is, the polarization voltage) and the previous measurement to obtain If the difference is greater than the polarization voltage threshold, it can be determined that lithium precipitation has occurred in the lithium battery.
- the polarization voltage of the lithium battery in this method cannot distinguish the positive and negative polarization voltages, and lithium precipitation mainly occurs at the negative electrode of the lithium battery. Therefore, determining whether lithium precipitation occurs in a lithium battery through the polarization voltage and polarization voltage threshold of the lithium battery may make the detection of lithium precipitation less reliable.
- the present application provides a method and device for detecting lithium precipitation in a lithium battery, according to the voltage of the lithium battery, the charging current of the lithium battery, the temperature of the lithium battery, the SOH of the lithium battery, and the corresponding relationship between the temperature and SOH of the lithium battery and target parameters , determine the lithium precipitation estimation model of the lithium battery, and then determine the real-time potential value of the negative electrode of the lithium battery, so that the present application can detect whether the lithium battery is subject to lithium precipitation according to the real-time potential value of the negative electrode, and improve the reliability of lithium precipitation detection.
- a method for detecting lithium evolution of a lithium battery comprising: determining the lithium battery according to the battery state of health SOH of the lithium battery and the temperature (of the lithium battery), as well as the corresponding relationship between the temperature and SOH of the lithium battery and target parameters.
- Target parameters corresponding to the battery are substituted into the preset lithium evolution estimation model, so as to obtain the lithium evolution estimation model of the lithium battery.
- the charging current, voltage, temperature and SOH of the lithium battery are input into the lithium precipitation estimation model of the lithium battery to obtain the real-time potential value of the negative electrode of the lithium battery. If the real-time potential value of the negative electrode of the lithium battery obtained by using the above-mentioned lithium deposition estimation model is less than zero, it is determined that lithium deposition occurs in the lithium battery.
- the target parameter corresponding to the lithium battery is the ratio of the polarization voltage of the negative electrode of the lithium battery to the polarization voltage of the lithium battery, and the polarization voltage is the difference between the actual voltage and the open circuit voltage. More specifically, the polarization voltage of the negative electrode of the lithium battery is the difference between the actual voltage of the negative electrode of the lithium battery and the open circuit voltage of the negative electrode of the lithium battery, and the polarization voltage of the lithium battery is the actual voltage of the lithium battery and the lithium battery. The difference in the open circuit voltage of the battery.
- the potential value of the negative electrode is zero, and lithium precipitation occurs at the negative electrode.
- the real-time potential value of the negative electrode can be more It directly and accurately reflects the state of the negative electrode of the lithium battery (that is, whether lithium precipitation occurs in the lithium battery). Therefore, by judging whether the real-time potential value of the negative electrode of the lithium battery is less than zero, it can be more directly and accurately determined whether lithium precipitation has occurred in the lithium battery, and the reliability of lithium precipitation detection can be improved.
- the target parameters in the lithium precipitation estimation model of the lithium battery can be determined according to the corresponding relationship between the temperature of the lithium battery and the SOH and the target parameters, so that the lithium battery can be directly According to the temperature, SOH, charging current, voltage and lithium battery estimation model of lithium battery, the real-time negative electrode potential value of lithium battery can be obtained, so as to ensure the reliability of lithium evolution detection, simplify the process of lithium evolution detection and improve lithium evolution detection efficiency.
- the target parameter corresponding to the lithium battery according to the SOH of the lithium battery, the temperature of the lithium battery, and the correspondence between the SOH of the lithium battery and the temperature of the lithium battery and the target parameter it is necessary to first determine the corresponding relationship between the SOH of the lithium battery and the temperature of the lithium battery and the target parameters, including: using the preset charging rate, the first charging rate, the second charging rate, and the third charging rate for lithium batteries with different temperatures and different SOH. battery charging.
- the OCV of the negative electrode of the battery is the reference potential of the negative electrode with respect to the lithium electrode.
- the corresponding temperature and pressure of the lithium battery under different SOC are obtained respectively, and the pressure is used to indicate the lithium battery during the charging process. Changes in external expansion volume.
- the corresponding lithium-evolution effect pressures of the lithium battery under different SOCs are determined, and the corresponding lithium-evolution effect pressures of the lithium battery under different SOCs are used to indicate that the lithium battery is formed by Pressure changes due to the lithium effect.
- the polarization of the negative electrode of the lithium battery is determined according to the OCV of the lithium battery corresponding to different SOCs, the OCV of the negative electrode of the lithium battery corresponding to the lithium battery at different SOCs, and the lithium evolution effect pressure corresponding to the lithium battery at different SOCs voltage and polarization voltage of lithium batteries.
- the target parameter is the ratio of the polarization voltage of the negative electrode of the lithium battery to the polarization voltage of the lithium battery.
- the polarization voltage of the lithium battery and the polarization voltage of the negative electrode of the lithium battery are determined by comparing the voltage of the lithium battery at the end of the lithium precipitation and the beginning of the lithium precipitation, the voltage of the negative electrode of the lithium battery, the OCV of the negative electrode of the lithium battery and the lithium battery. obtained by processing the OCV. Due to the high accuracy of the lithium-evolution end time and the lithium-evolution start time determined by the lithium-evolution effect pressure, the polarization of the negative electrode of the lithium battery is determined according to the voltage and the open-circuit voltage corresponding to the lithium-evolution end time and the lithium-evolution start time. The accuracy of the voltage and the polarization voltage of the lithium battery is higher, and the reliability of the lithium deposition detection of the obtained lithium deposition estimation model of the lithium battery is higher.
- the temperature and pressure corresponding to the lithium battery under different SOCs include a first temperature and a first pressure corresponding to the first charging rate, and a second temperature corresponding to the second charging rate and a second pressure, and a third pressure corresponding to the third charging rate.
- the first pressure is the total pressure caused by the occurrence of lithium ion deintercalation effect, temperature effect and lithium precipitation effect
- the second pressure is the total pressure caused by the occurrence of lithium ion deintercalation effect and temperature effect
- the third pressure is the occurrence of lithium ion deintercalation effect. Stress due to ion deintercalation effects.
- the relationship between the temperature effect pressure and temperature of the lithium battery is determined according to the difference between the second pressure and the third pressure under different SOCs and the second temperature.
- the temperature effect pressure of the lithium battery is used to indicate the pressure change caused by the temperature effect of the lithium battery at different temperatures.
- the corresponding temperature effect pressure of the lithium battery under different SOCs is determined.
- the difference between the sum of the temperature effect pressure and the third pressure corresponding to the lithium battery at different SOCs and the first pressure is determined as the lithium evolution effect pressure corresponding to the lithium battery at different SOCs.
- the pressure of the lithium precipitation effect is the pressure generated by the lithium precipitation of the lithium battery, that is to say, when the lithium battery does not undergo lithium precipitation, the lithium precipitation effect pressure of the lithium battery is zero.
- the lithium-evolution effect pressure can be used to determine whether the lithium battery has occurred.
- the sensitivity of lithium precipitation is high, and the reliability of lithium precipitation detection is also high.
- the OCV of the negative electrode of the lithium battery corresponding to the initial SOC is determined as the polarization voltage of the negative electrode, wherein the initial SOC, that is, the pressure value of the lithium deposition effect pressure, turns from zero is the corresponding SOC when it is non-zero.
- the difference between the OCV of the lithium battery and the (actual) voltage of the lithium battery corresponding to the termination SOC is determined as the polarization voltage of the lithium battery, wherein the termination SOC is the SOC corresponding to the maximum pressure value of the lithium precipitation effect pressure.
- the lithium-evolution effect pressure when the lithium-evolution effect pressure is zero, it is used to indicate that the lithium-evolution effect occurs in the lithium battery. Therefore, the SOC corresponding to when the pressure value in the lithium-evolution effect pressure changes from zero to non-zero can be determined as the lithium battery. The initial SOC at which lithium precipitation occurs, enabling accurate detection of the initial point of lithium precipitation.
- the lithium-evolution effect pressure when the lithium-evolution effect pressure is the maximum value during the charging process of the lithium battery, it is used to indicate the end of the lithium-evolution effect of the lithium battery. Therefore, the SOC corresponding to the maximum pressure value in the lithium-evolution effect pressure can be calculated. It is determined to be the termination SOC of the lithium battery when lithium evolution occurs, so as to realize accurate detection of the termination SOC of lithium evolution.
- the preset lithium precipitation estimation model is Among them, I is the charging current of the lithium battery, Q is the rated power of the lithium battery, ⁇ Idt is the electric capacity of the lithium battery at the current moment, SOC is the battery state of charge of the lithium battery, and V neg is the real-time potential value of the negative electrode of the lithium battery , OCV neg is the open circuit voltage of the negative electrode of the lithium battery, V p,neg is the polarization voltage of the negative electrode of the lithium battery, T is the temperature of the lithium battery, SOH is the battery state of health of the lithium battery, OCV neg (SOC, T, SOH ) is the function of OCV neg on SOC, T, SOH, ⁇ is the target parameter in the lithium evolution estimation model, V cell is the voltage of lithium battery, OCV cell (SOC, T, SOH) is the relationship between SOC, T, SOH of OCV cell A function of , V cell -OCV cell (SOC, T, SOH)
- the real-time potential value of the negative electrode of the lithium battery is obtained.
- the real-time potential value of the negative electrode of the lithium battery which is directly related to the lithium evolution of the lithium battery, it is determined whether the lithium battery has undergone lithium evolution, so as to ensure the reliability of the lithium battery lithium evolution detection.
- lithium precipitation alarm information is output, and the lithium precipitation alarm information includes the time when lithium precipitation occurs, the time when lithium precipitation terminates, and the SOC corresponding to the time when lithium precipitation occurs. , and at least one of the severity level of lithium precipitation, where the severity level of lithium precipitation is determined according to the duration of lithium precipitation and the real-time potential value of the negative electrode.
- the method further includes: adjusting the charging current of the lithium battery according to the real-time potential value of the negative electrode of the lithium battery.
- the current charging current can be adjusted, such as reducing the current charging current, so as to prevent the lithium battery from gradually moving away from the state of lithium precipitation and turn it into a safe charging state to ensure the safety of the lithium battery during charging. sex.
- the method further includes: determining the maximum safe charging current of the lithium battery according to the time when the lithium precipitation occurs and the SOC corresponding to the time when the lithium precipitation occurs.
- the charging current when charging the lithium battery, the charging current can be adjusted according to the maximum safe charging current allowed by the lithium battery under different conditions, so that the charging current is always within a safe charging current range, so as to ensure that the lithium The safety of the battery during charging.
- the corresponding relationship between the OCV of the lithium battery and its charging capacity, the OCV of the negative electrode of the lithium battery and the charging capacity of the negative electrode are obtained.
- the corresponding relationship between the capacity, and the corresponding relationship between the OCV of the positive electrode of the lithium battery and the charging capacity of the positive electrode are obtained.
- the voltage and charging capacity of the lithium battery are differentiated to obtain the dV/dQ curve of the lithium battery.
- the dV/dQ curve of the negative electrode of the lithium battery and the dV/dQ of the positive electrode of the lithium battery are obtained. curve.
- the dV/dQ curve of the negative electrode of the lithium battery and the dV/dQ curve of the positive electrode of the lithium battery are shifted or scaled, so that the dV/dQ curve of the negative electrode of the lithium battery is
- the characteristic peak of the curve and the characteristic peak of the dV/dQ curve of the positive electrode of the lithium battery are aligned with the characteristic peak of the dV/dQ curve of the lithium battery.
- the OCV of the lithium battery corresponding to the lithium battery at different SOC and the negative electrode corresponding to the lithium battery at different SOC are obtained. the OCV.
- the corresponding relationship is stored, so that in the subsequent lithium precipitation diagnosis process, the lithium battery can be directly and the corresponding relationship between the SOH and temperature of the lithium battery and the target parameters, determine the target parameters in the lithium evolution estimation model of the lithium battery, and obtain the required lithium evolution estimation model of the lithium battery.
- a lithium-evolution detection device of a lithium battery comprising: a target parameter determination unit for determining the unit according to the battery state of health SOH of the lithium battery, the temperature of the lithium battery, and the SOH of the lithium battery and the temperature of the lithium battery and the temperature of the lithium battery.
- the corresponding relationship of the target parameters determines the target parameters corresponding to the lithium battery.
- the target parameter corresponding to the lithium battery is the ratio of the polarization voltage of the negative electrode of the lithium battery to the polarization voltage of the lithium battery, and the polarization voltage is the difference between the actual voltage and the open circuit voltage.
- the model determination unit is used for substituting the target parameters corresponding to the lithium battery into the preset lithium evolution estimation model to obtain the lithium evolution estimation model of the lithium battery.
- the diagnostic parameter acquisition unit is used to input the charging current of the lithium battery, the voltage of the lithium battery, the temperature of the lithium battery and the SOH of the lithium battery into the lithium evolution estimation model of the lithium battery to obtain the real-time potential of the negative electrode of the lithium battery value.
- the lithium precipitation diagnosis unit is used to determine that the lithium battery has lithium precipitation if the real-time potential value of the negative electrode of the lithium battery is less than zero.
- the target parameter determination unit is further configured to: use a preset charging rate, a first charging rate, a second charging rate, and a third charging rate for different temperatures and different SOH lithium battery charging.
- the preset charging rate it is determined that the open circuit voltage OCV of the lithium battery corresponding to the SOC of the lithium battery under different battery states of charge and the OCV of the negative electrode of the lithium battery corresponding to the lithium battery under different SOC,
- the OCV of the negative electrode of the lithium battery is the reference potential of the negative electrode of the lithium battery relative to the lithium electrode.
- the corresponding temperature and pressure of the lithium battery under different SOC are obtained respectively, and the corresponding pressure of the lithium battery under different SOC is used for Indicates the change in the external expansion volume of the lithium battery during charging. Then, according to the corresponding temperature and pressure of the lithium battery under different SOCs, the corresponding lithium-evolution effect pressures of the lithium battery under different SOCs are determined, and the corresponding lithium-evolution effect pressures of the lithium battery under different SOCs are used to indicate that the lithium battery is formed by Pressure changes due to the lithium effect.
- the polarity of the negative electrode of the lithium battery is determined. polarization voltage and polarization voltage of lithium batteries.
- the temperature and pressure corresponding to the lithium battery under different SOCs include a first temperature and a first pressure corresponding to the first charging rate, and a second temperature corresponding to the second charging rate and a second pressure, and a third pressure corresponding to the third charging rate.
- the first pressure is the total pressure caused by the occurrence of lithium ion deintercalation effect, temperature effect and lithium precipitation effect
- the second pressure is the total pressure caused by the occurrence of lithium ion deintercalation effect and temperature effect
- the third pressure is the occurrence of lithium ion deintercalation effect. Stress due to ion deintercalation effects.
- the target parameter determination unit is specifically configured to: determine, according to the difference between the second pressure and the third pressure under different SOCs and the second temperature, and relationship between temperatures.
- the temperature effect pressure of the lithium battery is used to indicate the pressure change of the lithium battery caused by the temperature effect at different temperatures.
- the first temperature and the above-mentioned relationship in the process of charging the lithium battery with the first charging rate, the corresponding temperature effect pressure of the lithium battery under different SOCs is determined.
- the difference between the sum of the temperature effect pressure and the third pressure corresponding to the lithium battery at different SOCs and the first pressure is determined as the lithium evolution effect pressure corresponding to the lithium battery at different SOCs.
- the target parameter determination unit is specifically configured to: determine the OCV of the negative electrode of the lithium battery corresponding to the initial SOC as the polarization voltage of the negative electrode of the lithium battery, wherein the initial SOC is the SOC corresponding to the transition from zero to non-zero pressure value of the lithium deposition effect pressure.
- the difference between the OCV of the lithium battery and the (actual) voltage of the lithium battery corresponding to the termination SOC is determined as the polarization voltage of the lithium battery, wherein the termination SOC is the SOC corresponding to the maximum pressure value of the lithium precipitation effect pressure.
- the preset lithium precipitation estimation model is Among them, I is the charging current of the lithium battery, Q is the rated power of the lithium battery, ⁇ Idt is the electric capacity of the lithium battery at the current moment, SOC is the battery state of charge of the lithium battery, and V neg is the real-time potential value of the negative electrode of the lithium battery , OCV neg is the open circuit voltage of the negative electrode of the lithium battery, V p,neg is the polarization voltage of the negative electrode of the lithium battery, T is the temperature of the lithium battery, SOH is the battery state of health of the lithium battery, OCV neg (SOC, T, SOH ) is the function of OCV neg on SOC, T, SOH, ⁇ is the target parameter in the lithium evolution estimation model, V cell is the voltage of lithium battery, OCV cell (SOC, T, SOH) is the relationship between SOC, T, SOH of OCV cell A function of , V cell -OCV cell (SOC, T, SOH)
- the device further includes a lithium evolution alarm unit, and after it is determined that lithium evolution occurs in the lithium battery, the lithium evolution alarm unit is configured to output lithium evolution alarm information, where the lithium evolution alarm information includes At least one of the time of occurrence of lithium, the time of termination of lithium precipitation, the SOC corresponding to the time of occurrence of lithium precipitation, and the severity level of lithium precipitation, the severity level of lithium precipitation is determined according to the duration of lithium precipitation and the real-time potential value of the negative electrode of the lithium battery.
- lithium precipitation alarm information is output, and the lithium precipitation alarm information includes the time when lithium precipitation occurs, the time when lithium precipitation terminates, and the SOC corresponding to the time when lithium precipitation occurs. , and at least one of the severity level of lithium precipitation, where the severity level of lithium precipitation is determined according to the duration of lithium precipitation and the real-time potential value of the negative electrode.
- the device further includes a current control unit, which is configured to adjust the charging current of the lithium battery according to the real-time potential value of the negative electrode of the lithium battery.
- the device further includes a current control unit, the current control unit is configured to determine the maximum safe charging current of the lithium battery according to the time when the lithium precipitation occurs and the SOC corresponding to the time when the lithium precipitation occurs.
- the target parameter determination unit is specifically configured to obtain the correspondence between the OCV of the lithium battery and its charging capacity, the corresponding relationship between the OCV of the lithium battery and its charging capacity, and the The corresponding relationship between the OCV of the negative electrode and the charging capacity of the negative electrode, and the corresponding relationship between the OCV of the positive electrode of the lithium battery and the charging capacity of the positive electrode.
- the voltage and charging capacity of the lithium battery are differentiated to obtain the dV/dQ curve of the lithium battery.
- the dV/dQ curve of the negative electrode of the lithium battery and the dV/dQ curve of the positive electrode of the lithium battery can be obtained. dQ curve.
- the dV/dQ curve of the negative electrode of the lithium battery and the dV/dQ curve of the positive electrode of the lithium battery are shifted or scaled, so that the dV/dQ curve of the negative electrode of the lithium battery is
- the characteristic peak of the curve and the characteristic peak of the dV/dQ curve of the positive electrode of the lithium battery are aligned with the characteristic peak of the dV/dQ curve of the lithium battery.
- the OCV of the lithium battery corresponding to the lithium battery at different SOC and the negative electrode corresponding to the lithium battery at different SOC are obtained. the OCV.
- the target parameter determination unit establishes the corresponding relationship between the SOH, the temperature and the target parameter, and stores the corresponding relationship, so that in the subsequent lithium deposition diagnosis process, it is possible to directly According to the SOH and temperature of the lithium battery, and the corresponding relationship between the SOH and temperature of the lithium battery and the target parameters, the target parameters in the lithium evolution estimation model of the lithium battery are determined, and the required lithium evolution estimation model of the lithium battery is obtained.
- a device for applying a lithium battery includes a lithium battery, a charge and discharge unit, and a lithium precipitation detection device provided by the second aspect or any possible implementation manner of the second aspect, etc.;
- the charging and discharging unit is used to charge or discharge the lithium battery, and the apparatus is used to control the charging and discharging unit and execute the method provided by the first aspect or any possible implementation manner of the first aspect.
- the above-mentioned device applying the lithium battery may be a vehicle, and the vehicle may be a smart car or an electric vehicle (electric vehicle, EV) or the like.
- a computer-readable storage medium where instructions are stored in the computer-readable storage medium, and when the instructions are executed on a device, the device causes the device to perform the first aspect or the first A method for detecting lithium evolution of a lithium battery provided by any possible implementation manner of the aspect.
- a computer program product which, when running on a device, enables the device to execute the lithium ion provided by the first aspect or any possible implementation manner of the first aspect. Lithium deposition detection method for batteries.
- the device, equipment, computer-readable storage medium and computer program product of any lithium-ion battery detection method provided above are used to perform the corresponding method provided above, therefore, it can achieve For the beneficial effects, reference may be made to the beneficial effects in the corresponding methods provided above, which will not be repeated here.
- FIG. 1 is a schematic structural diagram of a vehicle according to an embodiment of the present application.
- FIG. 2 is a schematic structural diagram of a battery management system provided by an embodiment of the present application.
- FIG. 3 is a schematic flowchart of a method for detecting lithium evolution of a lithium battery provided in the embodiment of the present application;
- FIG. 4 is a schematic flowchart of another method for detecting lithium evolution of a lithium battery provided in the embodiment of the present application.
- 5(a) is a schematic diagram of the correspondence between OCV and SOC of a lithium battery, a positive electrode of a lithium battery, and a negative electrode of a lithium battery according to an embodiment of the present application;
- Fig. 5(b) is a schematic diagram of a dV/dQ curve of a lithium battery, a dV/dQ curve of a positive electrode of a lithium battery, and a dV/dQ curve of a negative electrode of a lithium battery provided by the embodiment of the application;
- FIG. 5(c) is a schematic diagram of the correspondence between the OCV and the SOC of an adjusted lithium battery and the negative electrode of the lithium battery provided by the embodiment of the present application;
- FIG. 6 is a schematic diagram of the relationship between a pressure value and SOC caused by a lithium-evolution effect provided in the embodiment of the present application;
- FIG. 7(a) is a schematic diagram 1 of the real-time potential of the negative electrode of a lithium battery under different SOCs provided by an embodiment of the present application;
- FIG. 7(b) is a schematic diagram 2 of the real-time potential of the negative electrode of a lithium battery under different SOCs provided by the embodiment of the present application;
- Fig. 7(c) is a schematic diagram of the cycle charging times of a lithium battery under different SOH provided by the embodiment of the present application;
- FIG. 8 is a schematic diagram of a measurement structure for measuring the pressure value of a lithium battery provided by an embodiment of the present application.
- FIG. 9 is a schematic flowchart of charging and discharging of a lithium battery according to an embodiment of the present application.
- FIG. 10 is a schematic structural diagram of a device for detecting lithium evolution of a lithium battery according to an embodiment of the present application.
- the charging rate is a measure of the speed of charging, which refers to the current value required by the battery to charge its rated capacity within a specified time. Usually represented by the letter C, where "/" represents the division symbol.
- the rated capacity of the battery is 100 ampere hours (ampere hour, Ah)
- the charging current is 5 ampere (ampere, A)
- the charging rate is 0.05C
- the charging current is 20A
- the charging rate is 0.2C
- the charging current is 0.2C
- the charging current is 0.2C
- the charging rate is 1C.
- the discharge rate is a measure of the speed of discharge, which refers to the current value required by the battery to discharge its rated capacity within a specified time. Usually represented by the letter C. For example, if the rated capacity of the battery is 100Ah, if the discharge current is 5A, the discharge rate is 0.05C, if the discharge current is 20A, the discharge rate is 0.2C, and if the discharge current is 100A, the discharge rate is 1C.
- Coulombic efficiency also known as discharge efficiency, refers to the ratio of battery discharge capacity to charging capacity during the same cycle, that is, the percentage of discharge capacity to charging capacity.
- the positive electrode material it is the lithium insertion capacity/delithiation capacity, that is, the discharge capacity/charge capacity; for the negative electrode material, it is the lithium removal capacity/lithium insertion capacity, that is, the discharge capacity/charge capacity, where "/" means division symbol.
- the state of charge (SOC) of the battery is a physical quantity used to reflect the remaining capacity of the battery.
- the state of health (SOH) of the battery is a physical quantity used to reflect the aging degree of the battery.
- SOC ranges from 0 to 1. The larger the SOC value, the better the health of the battery and the lower the aging degree of the battery.
- Lithium battery also known as lithium ion battery, is a secondary battery, usually using lithium compounds such as lithium cobalt oxide, lithium nickel oxide or lithium manganese oxide as the positive electrode material of the battery, using carbon such as petroleum coke or graphite The material is used as the negative electrode material of the battery.
- Lithium batteries mainly rely on the deintercalation and intercalation of lithium ions (Li+) between the positive and negative electrodes.
- Lithium batteries mainly rely on the deintercalation and intercalation of lithium ions (Li+) between the positive and negative electrodes.
- Li ions are deintercalated from the positive electrode of the battery into the electrolyte, and the lithium ions in the electrolyte are intercalated into the negative electrode.
- the lithium ions embedded in the negative electrode are extracted from the negative electrode into the electrolyte, and the lithium ions in the electrolyte are embedded into the positive electrode of the battery.
- the lithium ion deintercalation effect may refer to the characteristic that the relevant parameters of the lithium battery are changed due to the deintercalation and intercalation of lithium ions. Among them, the process of extracting lithium ions from the positive electrode material and inserting them into the negative electrode material will cause the volume of the lithium battery to expand, and this volume change will cause a change in the pressure of the lithium battery. The resulting stress is called the stress caused by the lithium ion deintercalation effect.
- the temperature effect may refer to the characteristic that the relevant parameters of the lithium battery change due to the temperature change of the lithium battery during the charging process of the lithium battery. Among them, in the process of charging the lithium battery, the temperature change of the lithium battery will cause thermal expansion of the lithium battery, and this thermal expansion will cause a change in the pressure of the lithium battery. In this application, the pressure generated by the temperature change is called the temperature effect. caused stress.
- Lithium precipitation refers to the process in which lithium ions are precipitated on the surface of the negative electrode to form metallic lithium when the lithium ions deintercalated from the positive electrode cannot be inserted into the negative electrode during the charging process of the lithium battery.
- the lithium precipitation effect may refer to the characteristic of changing the relevant parameters of the lithium battery caused by the lithium metal precipitated from the negative electrode during the charging process of the lithium battery. Among them, in the process of charging the lithium battery, the lithium metal precipitated from the negative electrode will cause the volume of the lithium battery to change. In this application, the pressure generated by the precipitated lithium metal is referred to as the pressure caused by the lithium precipitation effect.
- words such as “first” and “second” are used to distinguish the same or similar items with basically the same function and effect.
- the first threshold and the second threshold are only used to distinguish different thresholds, and the sequence of the first threshold is not limited.
- the words “first”, “second” and the like do not limit the quantity and execution order, and the words “first”, “second” and the like are not necessarily different.
- At least one means one or more
- plural means two or more.
- And/or which describes the association relationship of the associated objects, indicates that there can be three kinds of relationships, for example, A and/or B, which can indicate: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A, B can be singular or plural.
- the character “/” generally indicates that the associated objects are an “or” relationship.
- At least one item(s) below” or similar expressions thereof refer to any combination of these items, including any combination of single item(s) or plural items(s).
- At least one (a) of a, b or c may represent: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a combination of a, b and c Combination, where a, b, c can be single or multiple.
- the methods provided in the embodiments of the present application can be used to detect various forms of lithium batteries.
- the lithium battery in this application may be an aluminum-shell lithium battery, a steel-shell lithium battery, or a soft pack battery, etc.; in another feasible embodiment, the lithium battery in this application may be A two-electrode battery or a three-electrode battery, etc.; in another feasible embodiment, the lithium battery in this application may be a battery cell, a battery module, a battery pack, or the like.
- the methods provided in the embodiments of the present application can be applied to various devices using lithium batteries, and the lithium batteries can be used as energy storage devices or power devices in different devices.
- Various devices can include mobile phones, tablet computers, wearable devices, in-vehicle terminals and other terminal devices, as well as cars, trucks, motorcycles, buses, airplanes and other vehicles, and can also be used in base stations, mobile in communication equipment such as stations and satellites.
- the following takes a vehicle as an example to illustrate the structure of a device to which the method provided by the present application is applied.
- FIG. 1 is a functional block diagram of a vehicle 100 with an automatic driving function according to an embodiment of the present application.
- the vehicle 100 is configured in a fully or partially autonomous driving mode.
- the vehicle 100 may control its own driving state while in the autonomous driving mode, and may determine the current state of the vehicle and its surrounding environment through human operation, determine the possible behavior of at least one other vehicle in the surrounding environment, and determine other
- the vehicle 100 is controlled based on the likelihood of the vehicle performing possible actions based on the determined information.
- the vehicle 100 may be placed to operate without human interaction.
- a vehicle 100 may include various subsystems such as a travel system 102 , a sensor system 104 , a control system 106 , one or more peripherals 108 and a power supply 110 , a computer system 112 and a user interface 116 .
- vehicle 100 may include more or fewer subsystems, and each subsystem may include multiple elements. Additionally, each of the subsystems and elements of the vehicle 100 may be interconnected by wire or wirelessly.
- the travel system 102 may include components that provide powered motion for the vehicle 100 .
- travel system 102 may include engine 118 , energy source 119 , transmission 120 , and wheels 121 .
- the engine 118 may be an internal combustion engine, an electric motor, an air compression engine, or other types of engine combinations, such as a gasoline engine and electric motor hybrid engine, an internal combustion engine and an air compression engine hybrid engine.
- Engine 118 converts energy source 119 into mechanical energy.
- Examples of energy sources 119 include gasoline, diesel, other petroleum-based fuels, propane, other compressed gas-based fuels, ethanol, solar panels, batteries, and other sources of electricity.
- the energy source 119 may also provide energy to other systems of the vehicle 100 .
- Transmission 120 may transmit mechanical power from engine 118 to wheels 121 .
- Transmission 120 may include a gearbox, a differential, and a driveshaft.
- transmission 120 may also include other devices, such as clutches.
- the drive shaft may include one or more axles that may be coupled to one or more wheels 121 .
- the sensor system 104 may include several sensors that sense information about the environment surrounding the vehicle 100 .
- the sensor system 104 may include a positioning system 122 (eg, the positioning system may be a global positioning system (GPS) system, Beidou system or other positioning system), an inertial measurement unit (IMU) 124 , radar 126 , laser rangefinder 128 and camera 130 .
- the sensor system 104 may also include sensors of the internal systems of the vehicle 100 being monitored (eg, an in-vehicle air quality monitor, a fuel gauge, an oil temperature gauge, etc.). Sensor data from one or more of these sensors can be used to detect objects and their corresponding characteristics (position, shape, orientation, velocity, etc.). This detection and identification is a critical function for the safe operation of the autonomous vehicle 100 .
- the sensor system 104 may be used to measure state parameters such as the temperature and volume expansion pressure of the battery.
- the positioning system 122 may be used to estimate the geographic location of the vehicle 100 .
- the IMU 124 is used to sense position and orientation changes of the vehicle 100 based on inertial acceleration.
- IMU 124 may be a combination of an accelerometer and a gyroscope.
- Radar 126 may utilize radio signals to sense objects within the surrounding environment of vehicle 100 . In some embodiments, in addition to sensing objects, radar 126 may be used to sense the speed and/or heading of objects.
- the laser rangefinder 128 may utilize laser light to sense objects in the environment in which the vehicle 100 is located.
- the laser rangefinder 128 may include one or more laser sources, laser scanners, and one or more detectors, among other system components.
- Camera 130 may be used to capture multiple images of the surrounding environment of vehicle 100 .
- Camera 130 may be a still camera or a video camera.
- the control system 106 controls the operation of the vehicle 100 and its components.
- the control system 106 may include various elements, including a steering system 132, a throttle 134, a braking unit 136, a sensor fusion algorithm 138, a computer vision system 140, a route control system 142, and an obstacle avoidance system 144, which also It can be called an obstacle avoidance system.
- the steering system 132 is operable to adjust the heading of the vehicle 100 .
- the steering system 132 may be a steering wheel system.
- the throttle 134 is used to control the operating speed of the engine 118 and, in turn, the speed of the vehicle 100 .
- the braking unit 136 is used to control the deceleration of the vehicle 100 .
- the braking unit 136 may use friction to slow the wheels 121 .
- the braking unit 136 may convert the kinetic energy of the wheels 121 into electrical current.
- the braking unit 136 may also take other forms to slow the wheels 121 to control the speed of the vehicle 100 .
- Computer vision system 140 may be operable to process and analyze images captured by camera 130 in order to identify objects and/or features in the environment surrounding vehicle 100 .
- the objects and/or features may include traffic signals, road boundaries and obstacles.
- Computer vision system 140 may use object recognition algorithms, structure from motion (SFM) algorithms, video tracking, and other computer vision techniques.
- SFM structure from motion
- the computer vision system 140 may be used to map the environment, track objects, estimate the speed of objects, and the like.
- the route control system 142 is used to determine the travel route of the vehicle 100 .
- the route control system 142 may combine data from the sensor fusion algorithm 138 , the positioning system 122 and one or more predetermined maps to determine a driving route for the vehicle 100 .
- the obstacle avoidance system 144 is used to identify, evaluate and avoid or otherwise traverse potential obstacles in the environment of the vehicle 100 .
- control system 106 may include additional or alternative components in addition to those shown and described. Alternatively, some of the components shown above may be reduced.
- Peripherals 108 may include a wireless communication system 146 , an onboard computer 148 , a microphone 150 and/or a speaker 152 .
- peripherals 108 provide a means for a user of vehicle 100 to interact with user interface 116 .
- the onboard computer 148 may provide information to the user of the vehicle 100 .
- User interface 116 may also operate on-board computer 148 to receive user input.
- the onboard computer 148 can be operated via a touch screen.
- peripheral devices 108 may provide a means for vehicle 100 to communicate with other devices located within the vehicle.
- microphone 150 may receive audio (eg, voice commands or other audio input) from a user of vehicle 100 .
- speakers 152 may output audio to a user of vehicle 100 .
- Wireless communication system 146 may wirelessly communicate with one or more devices, either directly or via a communication network.
- the wireless communication system 146 may include an in-vehicle intelligent terminal (Telematics BOX, T-Box), and the T-Box may be installed in a place inside the vehicle 100 that is not easily accessible by human hands, such as under the dashboard, under the glove box or It's under the trunk.
- the T-Box can be mainly used to be responsible for the communication between the vehicle 100 and the Internet of Vehicles service platform.
- the T-Box can use 3G cellular communications such as code division multiple access (CDMA), global system for mobile communications (GSM), general packet radio service (GPRS) ) technology, or 4G cellular communications, such as long term evolution (LTE), or 5G cellular communications.
- the wireless communication system 146 may communicate with a wireless local area network (WLAN) using WiFi.
- the wireless communication system 146 may communicate directly with the device using an infrared link, Bluetooth, or ZigBee.
- Other wireless protocols, such as various vehicle communication systems, for example, wireless communication system 146 may include one or more dedicated short range communications (DSRC) devices, which may include communication between vehicles and/or roadside stations public and/or private data communications.
- DSRC dedicated short range communications
- the power supply 110 may provide power to various components of the vehicle 100 .
- the power source 110 may be a rechargeable lithium ion battery or a rechargeable lead acid battery.
- One or more battery packs of such a battery may be configured as a power source to provide power to various components of the vehicle 100 .
- power source 110 and energy source 119 may be implemented together, such as an all-electric vehicle.
- Computer system 112 may include at least one processor 123 that executes instructions 125 stored in a non-transitory computer-readable medium such as memory 114 .
- Computer system 112 may also be multiple computing devices that control individual components or subsystems of vehicle 100 in a distributed fashion.
- the processor 123 may be any conventional processor, such as a commercially available central processing unit (CPU). Alternatively, the processor may be a dedicated device such as application specific integrated circuits (ASIC) or other hardware-based processors.
- CPU central processing unit
- ASIC application specific integrated circuits
- FIG. 1 functionally illustrates a processor, memory, and other elements of the computer system 112 in the same blocks
- the processor, computer, or memory may actually include a processor, a computer, or a memory that may or may not Multiple processors, computers, or memories that are not stored within the same physical enclosure.
- the memory may be a hard drive or other storage medium located within an enclosure other than computer system 112 .
- reference to a processor or computer will be understood to include reference to a collection of processors or computers or memories that may or may not operate in parallel.
- some components such as the steering and deceleration components may each have their own processor that only performs computations related to component-specific functions .
- the memory 114 may include instructions 125 (eg, program logic) executable by the processor 123 to perform various functions of the vehicle 100 , including those described above.
- Memory 114 may also contain additional instructions, including instructions to send data to, receive data from, interact with, and/or control one or more of travel system 102 , sensor system 104 , control system 106 , and peripherals 108 . instruction.
- the memory 114 may store data such as road maps, route information, the vehicle's position, direction, speed, and other such vehicle data, among other information. Such information may be used by the vehicle 100 and the computer system 112 during operation of the vehicle 100 in autonomous, semi-autonomous and/or manual modes.
- a user interface 116 for providing information to or receiving information from a user of the vehicle 100 .
- user interface 116 may include one or more input/output devices within the set of peripheral devices 108 , such as wireless communication system 146 , onboard computer 148 , microphone 150 and speaker 152 .
- Computer system 112 may control functions of vehicle 100 based on input received from various subsystems (eg, travel system 102 , sensor system 104 , and control system 106 ) and from user interface 116 .
- computer system 112 may utilize input from control system 106 in order to control steering system 132 to avoid obstacles detected by sensor system 104 and obstacle avoidance system 144 .
- computer system 112 is operable to provide control of various aspects of vehicle 100 and its subsystems.
- the computer system 112 may include a battery management system (BMS), and the BMS may be used to manage the power supply 110, and specifically may be used to manage a lithium-ion battery.
- the BMS has the function of measuring the battery voltage, which can prevent or avoid the occurrence of abnormal conditions such as battery over-discharge, over-charge, or over-temperature.
- one or more of these components may be installed separately from the vehicle 100 , with the separately installed components being associated with the vehicle 100 .
- memory 124 may exist partially or completely separate from vehicle 100 .
- the above components may be communicatively coupled together in a wired and/or wireless manner, where communicatively coupled together means that a plurality of components coupled together may communicate.
- the above component is just an example.
- the components in the above-mentioned modules may be added or deleted according to actual needs, and FIG. 1 should not be construed as a limitation to the embodiments of the present application.
- a self-driving car traveling on a road can recognize objects within its surroundings to determine adjustments to the current speed.
- the objects may be other vehicles, traffic control equipment, or other types of objects.
- each identified object may be considered independently, and based on the object's respective characteristics, such as its current speed, acceleration, distance from the vehicle, etc., may be used to determine the speed at which the autonomous vehicle is to adjust.
- the autonomous vehicle vehicle 100 or a computing device associated with the autonomous vehicle 100 may be based on the characteristics of the identified objects and the state of the surrounding environment (eg, traffic, rain, ice on the road, etc.) to predict the behavior of the identified object.
- each identified object is dependent on the behavior of the other, so it is also possible to predict the behavior of a single identified object by considering all identified objects together.
- the vehicle 100 can adjust its speed based on the predicted behavior of the identified object.
- the self-driving car can determine what steady state the vehicle will need to adjust to (eg, accelerate, decelerate, or stop) based on the predicted behavior of the object.
- other factors may also be considered to determine the speed of the vehicle 100, such as the lateral position of the vehicle 100 in the road being traveled, the curvature of the road, the proximity of static and dynamic objects, and the like.
- the computing device may also provide instructions to modify the steering angle of the vehicle 100 so that the self-driving car follows a given trajectory and/or maintains contact with objects in the vicinity of the self-driving car (eg, , cars in adjacent lanes on the road) safe lateral and longitudinal distances.
- objects in the vicinity of the self-driving car eg, , cars in adjacent lanes on the road
- the above-mentioned vehicle 100 can be a car, a truck, a motorcycle, a bus, a boat, an airplane, a helicopter, a lawn mower, a recreational vehicle, a playground vehicle, construction equipment, a tram, a golf cart, a train, a cart, etc.
- the embodiment is not particularly limited.
- the embodiments of the present application may be applied to the BMS of other terminals, such as mobile phones, tablet computers, cameras, computers, netbooks, ultra-mobile personal computers (UMPCs), wearable devices (for example, smart bracelets and smart watches, etc.), in-vehicle devices or portable devices, etc.
- UMPCs ultra-mobile personal computers
- wearable devices for example, smart bracelets and smart watches, etc.
- portable devices etc.
- the BMS may include: a data acquisition module 201, a state estimation module 202, a lithium precipitation prevention management module 203, a lithium precipitation safety diagnosis module 204, an information record module 205 , cell balancing module 206 and communication module 207 .
- the data acquisition module 201 can be used to collect relevant parameter information of the lithium battery.
- the data acquisition module 201 can include: a voltage sensor, a current sensor, a temperature sensor and a pressure sensor, which are respectively used to collect the voltage, current, temperature and pressure of the lithium battery. and other parameter information.
- the state estimation module 202 can be used to estimate the relevant state of the lithium battery, for example, the state estimation module 202 can be used to estimate the remaining life of the lithium battery, whether the lithium battery is in a safe state, and the like.
- the lithium precipitation prevention management module 203 can be used to manage the maximum charging current threshold allowed when the lithium battery is charged under different conditions, and then control parameters such as the charging current of the charging and discharging unit according to the maximum charging current threshold under different conditions.
- the lithium precipitation safety diagnosis module 204 can be used to diagnose whether the lithium precipitation occurs in the lithium battery, and the starting point and the termination point of the lithium precipitation.
- the information recording module 205 can be used to record relevant parameters of the lithium battery, such as the current, voltage, temperature and pressure of the lithium battery.
- the battery balancing module 206 may be used for balancing the lithium batteries, for example, for balancing the voltage deviation of the lithium battery, so that the voltage deviation is within a certain range, and the like.
- the communication module 207 can be used to implement the communication between the BMS and other devices or units, for example, can be used to implement the communication between the BMS and the charging and discharging unit.
- each module in the above-mentioned BMS can be implemented by hardware, software, or a combination of hardware and software. Whether a specific module is implemented by hardware, software, or a combination of software and hardware It depends on the specific application of the technical solution and design constraints, which are not specifically limited in the embodiments of the present application.
- an embodiment of the present application provides a method for detection of lithium evolution of lithium batteries, which can be applied to various devices using lithium batteries, such as the vehicle 100 shown in FIG. 1 .
- the BMS may be executed or the processor may be executed, wherein the BMS and the processor may be arranged inside the vehicle 100 or outside the vehicle 100 .
- the method includes the following steps S301-S304:
- S301 Determine the target parameter corresponding to the lithium battery according to the battery state of health SOH of the lithium battery, the temperature of the lithium battery, and the corresponding relationship between the SOH of the lithium battery, the temperature of the lithium battery and the target parameter.
- the target parameter corresponding to the lithium battery is the ratio of the polarization voltage of the negative electrode of the lithium battery to the polarization voltage of the lithium battery.
- the polarization voltage is the difference between the actual voltage and the open circuit voltage. That is to say, the polarization voltage of the negative electrode of the lithium battery is the difference between the actual voltage of the negative electrode of the lithium battery and the open circuit voltage of the negative electrode of the lithium battery, and the polarization voltage of the lithium battery is the actual voltage of the lithium battery and the lithium battery. The difference in the open circuit voltage of the battery.
- the SOH of the lithium battery there is a corresponding relationship between the SOH of the lithium battery, the temperature of the lithium battery and the target parameter, and the corresponding relationship can be stored in the form of a table or the like. Therefore, after obtaining the SOH and temperature of the lithium battery, the target parameters corresponding to the lithium battery under the current conditions can be determined.
- the corresponding relationship between the SOH of the lithium battery, the temperature of the lithium battery and the target parameter may be as shown in Table 1 below.
- the preset lithium precipitation estimation model is I is the charging current of the lithium battery, Q is the rated capacity of the lithium battery, ⁇ Idt is the capacity of the lithium battery at the current moment, SOC is the battery state of charge of the lithium battery, V neg is the real-time potential value of the negative electrode of the lithium battery, OCV neg is the open circuit voltage of the negative electrode of the lithium battery, V p,neg is the polarization voltage of the negative electrode of the lithium battery, T is the temperature (of the lithium battery), SOH is the battery state of health of the lithium battery, OCV neg (SOC, T, SOH) is the function of OCV neg on SOC, T, and SOH, ⁇ is the target parameter in the estimation model of lithium deposition, V cell is the voltage of the lithium battery, and OCV cell (SOC, T, SOH) is the OCV cell ’s relation to SOC, T, and SOH
- the function, V cell -OCV cell (SOC, T, SOH) represents the polarization voltage of the
- the target parameter ⁇ in the lithium precipitation estimation model is the ratio of the polarization voltage of the negative electrode of the lithium battery to the polarization voltage of the lithium battery, and the SOC is obtained from the charging current, charging time and rated power of the lithium battery.
- OCV neg indicates that the value of OCV neg can be calculated according to the values of SOC, T and SOH or obtained by looking up a table, etc.
- OCV cell indicates the value of OCV cell It can be calculated according to the values of SOC, T and SOH or obtained by looking up a table.
- the target parameter corresponding to the lithium battery can be determined to be ⁇ 3 .
- the charging current is the charging current from the starting moment of charging the lithium battery to the current moment.
- the charging current is the charging current from the starting moment of charging the lithium battery to the current moment.
- the lithium evolution estimation model of the lithium battery can determine the real-time potential value V neg of the negative electrode of the lithium battery.
- the present application can, without destroying the integrity of the battery, i.e. Without modifying or disassembling the battery, the charging current, voltage, temperature, and SOH of the lithium battery can be directly obtained and input into the lithium evolution estimation model of the lithium battery to obtain the real-time potential of the negative electrode of the lithium battery, and then according to The real-time potential of the negative electrode of the lithium battery determines whether lithium precipitation occurs in the lithium battery.
- the lithium precipitation condition is activated, and the lithium battery undergoes lithium precipitation; if the real-time potential value of the negative electrode of the lithium battery is greater than zero, the lithium precipitation condition is deactivated, and the lithium battery does not occur. lithium. Therefore, if the real-time potential value of the negative electrode of the lithium battery obtained by using the lithium-evolution estimation model is less than zero, it is determined that the lithium-ion battery has undergone lithium-evolution; Lithium precipitation does not occur in the lithium battery; if the real-time potential value of the negative electrode of the lithium battery obtained by using the lithium precipitation estimation model is zero, it is considered that the lithium battery starts to precipitate or ends.
- the lithium evolution estimation model of the lithium battery by inputting the temperature, SOH, charging current, and voltage of the lithium battery at each moment during the charging process into the lithium evolution estimation model of the lithium battery, it can be determined that the lithium battery is in the charging process.
- the real-time potential value of the negative electrode at each moment in the lithium battery is determined, so as to determine the moment when the lithium battery starts to precipitate lithium, the moment when the lithium precipitation ends, and the degree to which the real-time potential value of the negative electrode is less than zero during the process of lithium evolution. Then, according to the time when the obtained lithium battery starts to precipitate lithium, the time when it ends, or the degree to which the real-time potential value of the negative electrode is less than zero during the process of lithium evolution, the severity of lithium evolution of the lithium battery can be determined.
- lithium precipitation alarm information is output.
- the lithium precipitation alarm information includes at least one of the lithium precipitation occurrence time, the lithium precipitation termination time, the SOC corresponding to the lithium precipitation occurrence time, and the lithium precipitation severity level.
- the severity level of lithium precipitation is determined according to the duration of lithium precipitation of the lithium battery and the real-time potential value of the negative electrode of the lithium battery.
- the charging current of the lithium battery can be adjusted according to the magnitude of the real-time potential value. For example, the charging current of the lithium battery is reduced, so that the lithium battery is kept away from the lithium precipitation state and is in a safe charging state, thereby ensuring the safety of the lithium battery during the charging process.
- the real-time potential value of the negative electrode of the lithium battery is low, for example, less than or equal to zero, or greater than zero but less than the preset potential threshold, the risk of lithium precipitation in the lithium battery is high, and the charging of the lithium battery can be appropriately reduced. If the real-time potential value of the negative electrode of the lithium battery is greater than zero or the preset potential threshold, the charging current of the lithium battery can be appropriately increased to increase the safety of the lithium battery charging process. Improve the charging rate of lithium batteries.
- the charging speed of the lithium battery can be improved as much as possible while ensuring the charging safety of the lithium battery, and the charging experience of the user can be improved.
- the real-time potential of the negative electrode of the lithium battery under different temperatures, different SOH and different SOC can be obtained, so that according to the real-time potential and charging rate of the negative electrode of the lithium battery, different SOH, different
- the maximum charging rate corresponding to the lithium battery without lithium precipitation under different SOCs and temperature, and then according to the maximum charging rate and the capacity of the lithium battery, the maximum safe charging current allowed by the lithium battery is determined.
- the maximum safe charging current allowed by the lithium battery can be determined by measuring offline or in the on-board environment.
- the maximum safe charging current allowed by the lithium battery under different conditions can be stored in the BMS as the maximum safe charging current threshold; when the measurement is carried out in the on-board environment, the BMS can directly measure different values.
- the maximum safe charging current threshold allowed by the lithium battery under the conditions In this way, when the BMS controls the charging and discharging unit to charge the lithium battery, it can adjust the charging current according to the maximum safe charging current threshold allowed by the lithium battery under different conditions, so that the charging current is always within the safe charging current range, thus ensuring that the lithium battery Safety during charging.
- the real-time potential of the negative electrode of the lithium battery can be obtained. value, and then determine whether lithium precipitation occurs in the lithium battery according to the real-time potential value of the negative electrode, so as to simplify the process of lithium precipitation detection. Since the lithium obtained by the lithium battery after lithium precipitation is distributed on the negative electrode of the lithium battery, compared with other parameters, the real-time potential value of the negative electrode can more accurately indicate whether lithium precipitation has occurred in the lithium battery to ensure that the precipitation occurs in the lithium battery. Reliability of Lithium Detection.
- the present application also provides a method for detecting lithium evolution of a lithium battery, which is used to determine the SOH and temperature of the lithium battery and an estimation model for lithium evolution of the lithium battery.
- the correspondence between the target parameters in . the method includes the following steps S401-S406:
- S401 Use a preset charging rate, a first charging rate, a second charging rate, and a third charging rate to charge lithium batteries with different temperatures and different SOHs.
- S402. Determine the open circuit voltage OCV of the lithium battery corresponding to the lithium battery at different SOCs and the OCV of the negative electrode of the lithium battery corresponding to the lithium battery at different SOCs.
- the open circuit voltage OCV of the lithium battery corresponding to different SOCs and the OCV of the negative electrode of the lithium battery corresponding to the lithium battery at different SOCs are determined.
- the OCV of the negative electrode of the lithium battery is the reference potential of the electrode composed of the negative electrode material relative to the lithium electrode, and the lithium electrode is the reference electrode.
- the reference electrode is the electrode that is used as a reference for comparison when measuring various electrode potentials.
- the reference electrode can also select other suitable materials according to the actual application.
- the reference electrode is a lithium electrode as an example to introduce the technical solution.
- transform the lithium battery into a three-electrode battery, or construct a negative button battery that is, use the negative electrode material of the lithium battery as the negative electrode and use lithium as the positive electrode to construct the negative button battery.
- the lithium battery and the negative button battery are charged at the same preset charging rate, and during the charging process, the open circuit voltage and charging capacity of the lithium battery and the negative button battery are detected, so as to obtain the open circuit voltage of the two batteries during the charging process. Variation of voltage with charge capacity.
- the ratio of the charging capacity of the lithium battery and the negative button battery to the rated power of the battery that is, the SOC of the lithium battery and the SOC of the negative button battery, determine the change of the open circuit voltage of the two batteries with their respective SOC during the charging process, so as to determine The OCV of the lithium battery corresponding to the SOC of the lithium battery at different battery states of charge, and the OCV of the negative electrode corresponding to the lithium battery at different SOC.
- the OCV of the negative coin cell battery is the OCV of the negative electrode of the lithium battery.
- the corresponding relationship between the OCV of the lithium battery and its charging capacity, and the corresponding relationship between the OCV of the negative electrode of the lithium battery and the charging capacity of the negative electrode are obtained.
- the dV/dQ curve of the lithium battery and the dV/dQ curve of the negative electrode of the lithium battery are obtained.
- a translation or scaling process (and/or ICA characteristic analysis) is performed on the dV/dQ curve of the negative electrode of the lithium battery, so that the dV/dQ curve of the negative electrode of the lithium battery is
- the characteristic peaks are aligned with the characteristic peaks of the dV/dQ curve of lithium batteries. According to the dV/dQ curve of the negative electrode of the lithium battery and the dV/dQ curve of the lithium battery after the characteristic peaks are aligned, the OCV of the lithium battery corresponding to the lithium battery at different SOC and the corresponding negative electrode of the lithium battery at different SOC are obtained. OCV.
- a positive coin cell battery can also be constructed with the positive electrode of the lithium battery as the positive electrode and lithium as the negative electrode.
- the open circuit voltage and charging capacity of the positive button battery are detected, so as to obtain the process that the open circuit voltage of the positive button battery changes with its charging capacity during the charging process.
- the OCV of the positive electrode corresponding to the lithium battery under different SOCs is determined, wherein the OCV of the positive button battery is the OCV of the positive electrode of the lithium battery.
- the dV/dQ curve of the positive electrode of the lithium battery can also be obtained based on the corresponding relationship between the OCV of the positive electrode of the lithium battery and the charging capacity of the positive electrode. And based on the characteristic peaks in the dV/dQ curve of the lithium battery, the dV/dQ curve of the positive electrode of the lithium battery is shifted or scaled, so that the characteristic peak of the dV/dQ curve of the positive electrode of the battery is the same as the dV/dQ curve of the lithium battery. characteristic peak alignment.
- Exemplarily use a charging rate of 1/20C to charge a lithium battery, a negative button battery, and a positive button battery to obtain the corresponding relationship between the OCV of the lithium battery and its charging capacity, and the OCV of the negative electrode of the lithium battery (that is, the OCV of the negative button battery)
- the corresponding relationship with the charging capacity of the negative button battery, and the corresponding relationship between the OCV of the positive electrode of the lithium battery (ie the OCV of the positive button battery) and the charging capacity of the positive button battery are shown in Figure 5(a), respectively.
- the abscissa shown in Figure 5(a) is the SOC of the lithium battery, the SOC of the positive button battery, and the SOC of the negative button battery (or the abscissa can also be the charging capacity of the lithium battery, Positive button battery charging capacity, negative button battery charging capacity), the ordinate is lithium battery OCV, lithium battery positive OCV or lithium battery negative OCV. According to the corresponding relationship shown in Figure 5(a), differential analysis is performed to obtain the dV/dQ curves of the lithium battery, the positive electrode of the lithium battery, and the negative electrode of the lithium battery, respectively.
- the abscissa is the SOC
- the ordinate is the dV/dQ value of the lithium battery, the positive electrode of the lithium battery, and the negative electrode of the lithium battery.
- the charging capacity of the lithium battery is calculated according to the charging current of the lithium battery from the start of charging to the current moment.
- the preset charging rate is a smaller charging rate, and charging the lithium battery at a smaller charging rate can avoid the polarization effect of the lithium battery.
- the preset charging rate may be 1/20C or the like.
- the lithium battery when constructing a positive button battery and a negative button battery, the lithium battery can be drained and left to stand, so that the positive active material and negative active material of the lithium battery are in a relatively safe state, and then the lithium battery can be disassembled. Then, the same electrolyte, lithium electrode, and negative electrode active material and positive electrode active material of the disassembled lithium battery as those in the lithium battery are selected to construct the required positive electrode button battery and negative electrode button battery. Among them, the assembly of the entire button battery and the disassembly of the lithium battery are carried out in the glove box.
- the corresponding pressure of the lithium battery under different SOC is used to indicate the change of the external expansion volume of the lithium battery during the charging process.
- the relevant state parameters such as the temperature and pressure of the lithium battery will change differently.
- the pressure change of the lithium battery under different charging rates may come from the lithium ion deintercalation effect pressure, One or more of temperature effect pressure or lithium evolution effect pressure. Therefore, in a possible implementation manner, for each charging rate among the first charging rate, the second charging rate, and the third charging rate, in the process of using the charging rate to charge the lithium battery, detect the lithium battery The pressure and temperature, etc., so that the three charging rates correspond to three sets of temperatures and pressures.
- the corresponding temperatures and pressures of the lithium battery under different SOCs include a first temperature and a first pressure, a second temperature and a second pressure, and (a third temperature and) a third pressure.
- the corresponding temperature and pressure of the lithium battery under different SOCs are the first temperature and the first pressure
- the first pressure is the total amount of the lithium ion deintercalation effect, temperature effect and lithium precipitation effect.
- the corresponding temperature and pressure of the lithium battery under different SOCs are the second temperature and the second pressure, and the second pressure is the total pressure caused by the lithium ion deintercalation effect and the temperature effect;
- the corresponding temperature and pressure of the lithium battery at different SOCs are the third temperature and the third pressure, respectively, and the third pressure is the pressure caused by the lithium ion deintercalation effect.
- each set of charging ratios may include at least one charging ratio, and the at least one charging ratio belongs to the same charging ratio, that is, the first charging ratio , or the second charging rate, or the third charging rate.
- the three sets of charging ratios include the first set of charging ratios, the second set of charging ratios, and the third set of charging ratios, the charging ratios in the first set of charging ratios belong to the first charging ratio, and the charging ratios in the second set of charging ratios
- the charging rate of 1 belongs to the second charging rate, and the charging rate in the third group of charging rates belongs to the third charging rate.
- the first charging rate is the charging rate at which the lithium battery has the lithium electron deintercalation effect, the temperature effect and the lithium precipitation effect
- the second charging rate is the charging rate where the lithium battery only has the lithium electron deintercalation effect and the temperature effect.
- the third charging rate is the charging rate at which only the lithium electron deintercalation effect occurs in the lithium battery.
- the higher the charging rate the greater the possibility of lithium precipitation in the lithium battery.
- the value range of the first charging rate is [a1, b1]
- the value range of the second charging rate is [a2, b2]
- the value range of the third charging rate is [a3, b3]
- [a1 , b1] is greater than [a2, b2]
- [a2, b2] is greater than [a3, b3].
- [a1, b1] is equal to [3C, 5C]
- [a2, b2] is equal to [0.5C, 2C]
- [a3, b3] is equal to [0.05C, 0.2C].
- the value ranges of the above charging rates may be different.
- each group of charging rates can detect multiple groups of pressures and temperatures correspondingly. For example, select the pressure and temperature corresponding to the smallest charging rate in each group of charging rates as the pressure and temperature corresponding to the charging rate in this group, or calculate the average value of multiple groups of pressures and temperatures detected corresponding to each group of charging rates to obtain a Group pressure and temperature, or determine a group of pressure and temperature from multiple groups of pressure and temperature detected corresponding to each group of charging rates by a certain mathematical combination, which is not specifically limited in this embodiment of the present application.
- the pressure changes of lithium batteries under different charging rates are described below. Specifically, when the lithium battery is charged at the third charging rate, the temperature of the lithium battery does not change much, and no lithium precipitation occurs. There is no temperature effect and lithium precipitation effect, that is to say, the pressure change of the lithium battery is caused by the lithium ion deintercalation effect, that is, the pressure of the lithium battery is the lithium ion deintercalation effect pressure, and the lithium ion deintercalation effect pressure can be is a function of the SOC of the lithium battery. When the lithium battery is charged at the second charging rate, the temperature of the lithium battery changes significantly, but no lithium precipitation occurs.
- the lithium ion deintercalation effect and temperature effect occur in the lithium battery during the charging process.
- the lithium precipitation effect occurs, so the pressure change of the lithium battery is caused by the lithium ion deintercalation effect and the temperature effect, that is, the pressure of the lithium battery is the sum of the lithium ion deintercalation effect pressure and the temperature effect pressure, and the temperature effect pressure can be A function of the temperature of a lithium battery.
- the temperature of the lithium battery changes significantly, and the phenomenon of lithium precipitation may occur at the same time.
- Lithium effect so the pressure change of lithium battery is caused by lithium ion deintercalation effect, temperature effect and lithium precipitation effect, that is, the pressure of lithium battery is the sum of lithium ion deintercalation effect pressure, temperature effect pressure and lithium precipitation effect pressure .
- the charging rate includes the first charging rate, the second charging rate and the third charging rate, etc.
- the pressure of the lithium battery at the first charging rate (ie the first pressure) is equal to the pressure caused by the lithium ion deintercalation effect
- the sum of the pressure caused by the temperature effect and the pressure caused by the lithium deposition effect, the pressure of the lithium battery at the second charging rate (ie the second pressure) is equal to the pressure caused by the lithium ion deintercalation effect and the pressure caused by the temperature effect.
- the pressure of the lithium battery at the third charging rate ie, the third pressure
- the third pressure is equal to the pressure caused by the lithium ion deintercalation effect.
- first charging rate, the second charging rate and the third charging rate corresponding to lithium batteries of different specifications or different forms may be the same or different, which are not specifically limited in the embodiments of the present application.
- the above-mentioned first charging rate, second charging rate and third charging rate can be set in advance by those skilled in the art according to the specifications or forms of the detected lithium battery, for example, the third charging rate can include 0.05C, 0.1C and 0.2C etc.
- the second charging rate may include 0.5C, 1C, and 2C, etc.
- the first charging rate may include 3C, 4C, 5C, and the like.
- the temperature of the lithium battery can be measured by a temperature sensor
- the pressure of the lithium battery can be measured by a pressure sensor
- the charging current of the lithium battery can be measured by a current sensor.
- the lithium battery is cyclically charged using the first charging rate, and the average value of the data (such as the above-mentioned temperature and pressure) detected during the charging process corresponding to the first charging rate is used as the first charging rate.
- the charging rate refers to the corresponding data of the lithium battery under different SOCs when charging the lithium battery.
- the average value of the data detected during the charging process corresponding to the second charging rate is used as the data corresponding to the lithium battery under different SOCs when the lithium battery is charged using the second charging rate.
- the average value of the data detected during the charging process corresponding to the third charging rate is taken as the data corresponding to the lithium battery under different SOCs when the lithium battery is charged using the third charging rate.
- the lithium-evolution effect pressure of the lithium battery is used to indicate the pressure change of the lithium battery caused by the lithium-evolution effect.
- the lithium-evolution effect pressure please refer to the above content.
- the temperature effect pressure is used to indicate that the lithium battery is in different conditions. Pressure changes at temperature due to temperature effects. Among them, the temperature effect pressure is used to indicate the pressure change caused by the temperature effect of the lithium battery at different temperatures. Then, according to the first temperature and the relationship between the temperature effect pressure and the temperature, in the process of charging the lithium battery with the first charging rate, the temperature effect pressure of the lithium battery corresponding to different SOCs of the lithium battery is determined. Finally, the difference between the sum of the temperature effect pressure and the third pressure of the lithium battery and the first pressure is determined as its corresponding lithium evolution effect pressure under different SOCs.
- the corresponding first temperature and first pressure under different SOCs can be expressed as ⁇ (T 11 , F 11 ), (T 12 , F 12 ), ..., (T 1n , F 1n ) ⁇ .
- the corresponding second temperature and second pressure under different SOC can be expressed as ⁇ (T 21 , F 21 ), (T 22 , F 22 ), ... ..., (T 2n , F 2n ) ⁇ .
- the corresponding third temperature and third pressure under different SOC can be expressed as ⁇ (, T 31 , F 31 ), (T 32 , F 32 ), ..., ( T 3n , F 3n ) ⁇ .
- T is the temperature of the lithium battery
- F is the pressure.
- the charging current of the lithium battery since the charging current of the lithium battery is integrated, the charging capacity of the lithium battery can be obtained, and then the SOC of the lithium battery can be obtained. Therefore, to a certain extent, the corresponding first temperature and first pressure under different SOCs can be expressed as ⁇ (I 11 , T 11 , F 11 ), (I 12 , T 12 , F 12 ), , ( I 1n , T 1n , F 1n ) ⁇ .
- I is the charging current of the lithium battery, which can be used to represent the SOC of the lithium battery corresponding to the first temperature and the first pressure.
- V is the voltage of the lithium battery at different SOCs.
- the corresponding second temperature and second pressure under different SOC can be expressed as ⁇ (I 21 , T 21 , F 21 ), (I 22 , T 22 , F 22 ), ..., (I 2n , T 2n , F 2n ) ⁇ .
- the corresponding third temperature and third pressure under different SOC ⁇ (I 31 , T 31 , F 31 ), (I 32 , T 32 , F 32 ), ... , (I 3n , T 3n , F 3n ) ⁇ .
- the relevant information of the lithium battery can be expressed as ⁇ (I 11 , V 11 , T 11 , F 11 ), (I 12 , V 12 , T 12 , F 12 ), ..., (I 1n , V 1n , T 1n , F 1n ) ⁇ .
- the relevant information of the lithium battery can be expressed as ⁇ (I 21 , V 21 , T 21 , F 21 ), (I 22 , V 22 , T 22 , F 22 ) , ..., (I 2n , V 2n , T 2n , F 2n ) ⁇ .
- the relevant information of the lithium battery can be expressed as ⁇ (I 31 , V 31 , T 31 , F 31 ), (I 32 , V 32 , T 32 , F 32 ), ..., (I 3n , V 3n , T 3n , F 3n ) ⁇ .
- I is the charging current of the lithium battery
- V is the charging voltage of the lithium battery
- T is the temperature of the lithium battery
- F is the pressure of the lithium battery.
- D21 ⁇ (SOC 21 , ⁇ T 21 , F 21 ), (SOC 22 , ⁇ T 22 , F 22 ), ..., (SOC 2n , ⁇ T 2n , F 2n ) ⁇
- D31 ⁇ (SOC 31 , F 31 ), (SOC 32 , F 32 ), ..., (SOC 3n , F 3n ) ⁇ .
- SOC 21 SOC 31
- SOC 22 SOC 32 , . . .
- SOC 2n SOC 3n .
- F 3i is the lithium ion deintercalation effect pressure corresponding to different SOCs at the third charging rate
- F 2i is the sum of the lithium ion deintercalation effect pressure and temperature effect pressure corresponding to different SOCs at the second charging rate.
- ⁇ T 2i T 2i ⁇ T 21
- the value range of i is 1 ⁇ n (n is a positive integer).
- ⁇ T 1i T 1i -T 11 .
- F 1i is the lithium ion deintercalation effect pressure F′ 1i at the first charging rate
- ⁇ T 3i T 3i -T 31
- the value of i ranges from 1 to n.
- a certain discharge rate is used to discharge the lithium battery, and at the same time, information such as current, pressure, voltage, and temperature of the lithium battery can also be detected during the discharge process, so as to determine whether the lithium battery is in different Lithium evolution effect pressure at SOC.
- the polarity of the negative electrode of the lithium battery is determined according to the OCV of the lithium battery corresponding to different SOCs, the OCV of the negative electrode corresponding to the lithium battery at different SOCs, and the lithium evolution effect pressure corresponding to the lithium battery at different SOCs.
- polarization voltage and polarization voltage of lithium batteries are determined according to the OCV of the lithium battery corresponding to different SOCs, the OCV of the negative electrode corresponding to the lithium battery at different SOCs, and the lithium evolution effect pressure corresponding to the lithium battery at different SOCs.
- the lithium-evolution of the lithium battery can be detected according to the change of the pressure value in the lithium-evolution effect pressure.
- the lithium-evolution effect pressure includes multiple pressure values of different SOCs, and since the lithium-evolution effect pressure is caused by the lithium-evolution effect, the lithium-evolution effect pressure value of different SOCs can be changed to determine the occurrence of the lithium battery.
- the pressure value in the lithium-evolution effect pressure When the pressure value in the lithium-evolution effect pressure is zero or close to zero, it can be determined that no lithium-evolution has occurred in the lithium battery; when the pressure value in the lithium-evolution effect pressure increases from zero to non-zero, and is still in an upward trend, It can be determined that lithium precipitation has occurred in the lithium battery, that is to say, the corresponding SOC when the pressure value in the lithium precipitation effect pressure is converted from zero to non-zero can be determined as the initial SOC of lithium precipitation in the lithium battery; when the lithium precipitation effect causes When the pressure value in the pressure rises to the maximum value and starts to decrease gradually, it can be determined that the lithium evolution of the lithium battery ends, that is to say, the SOC corresponding to the maximum pressure value in the lithium evolution effect pressure can be determined as the end of the lithium evolution of the lithium battery. terminating SOC.
- the negative electrode voltage value is zero, that is, the difference between the negative electrode OCV corresponding to the initial SOC and the polarized voltage of the negative electrode is zero. Therefore, the OCV of the negative electrode of the lithium battery corresponding to the initial SOC can be determined as the polarization voltage of the negative electrode.
- the polarization voltage of the lithium battery is the difference between the voltage of the lithium battery corresponding to the termination SOC and the OCV of the lithium battery corresponding to the termination SOC.
- point A represents the transition point when the pressure value in the lithium-evolution effect pressure changes from zero to non-zero and is still in an upward trend
- point B represents the peak point corresponding to the maximum pressure value in the lithium-evolution effect pressure.
- point A (0.55,0) can be called the starting point of lithium precipitation
- point B (0.87, 230) can be called the termination point of lithium evolution
- the above steps S402 and S405 are performed.
- the polarization voltage of the negative electrode of the lithium battery and the polarization voltage of the lithium battery corresponding to the lithium battery at the temperature and the SOH are determined in step S405, the corresponding relationship between the temperature and the SOH of the lithium battery and the target parameter can be established,
- the target parameter is the ratio of the polarization voltage of the negative electrode of the lithium battery to the polarization voltage of the lithium battery obtained through step S405.
- the correspondence between other temperatures and SOH of the lithium battery and the target parameters can be established, and the correspondence between other lithium batteries at different temperatures and SOH and the target parameters can also be established.
- the corresponding relationship may be stored in the form of a table, as shown in Table 1 above.
- the polarizing voltage of the negative electrode of the lithium battery is 86.1mV and the polarizing voltage of the lithium battery is 212.7V after the above steps, the difference between the polarizing voltage of the negative electrode of the lithium battery and the polarizing voltage of the lithium battery can be obtained.
- the ratio ⁇ is 0.4048.
- the ratio of the polarization voltage of the negative electrode of the lithium battery to the polarization voltage of the lithium battery can be regarded as not changing with the SOC or charging rate, but with the SOH and temperature of the lithium battery. , that is, the ratio has a corresponding relationship with the SOH and temperature of the lithium battery.
- the real-time potential of the negative electrode of the lithium battery is always greater than zero, and it can be determined that the lithium battery does not have lithium precipitation;
- the real-time potential of the negative electrode of the lithium battery is less than zero, that is, when the SOC of the lithium battery is 0.62-0.89 Lithium precipitation occurred.
- the lithium battery with different SOH was cyclically charged at 1C and 1.5C charging rate, and the number of cycles that the lithium battery could be charged under different SOH was obtained. As shown in Fig.
- Fig. 7(c) when the SOH of the lithium battery is 80.00%, use The process of charging the lithium battery at 1.5C can be cycled 180 times, and the process of charging the lithium battery at 1C can be cycled 1500 times, and 180 is much less than 1500. Therefore, Fig. 7(c) can indirectly reflect that during the process of charging the lithium battery with 1.5C, the lithium battery is likely to undergo lithium precipitation. To sum up, it can be determined from Fig. 7(a), Fig. 7(b) and Fig. 7(c) that the present application can more accurately determine whether lithium precipitation occurs during the charging process of the lithium battery.
- the lithium battery and the pressure sensor may be fixed.
- the cell and the pressure sensor can be fixed by an aluminum plate, or the battery module and the pressure sensor can be fixed by the aluminum plate, and the aluminum plate can be fixed by bolts to Guarantee the measurement accuracy and stability of the pressure value.
- the lithium battery is usually charged and discharged multiple times with the same charging rate.
- the multiple charging and discharging process includes step S901 -S907:
- venting operation first venting the lithium battery (also known as discharge operation), such as using a constant current and constant voltage discharge method or other discharge methods, the purpose of the discharge operation is to make the SOC of the lithium battery close to 0%, such as The SOC of the lithium battery is 0-5%.
- a standing operation the purpose of the standing operation is to make the lithium battery in an electric-heat-chemical-pressure quasi-equilibrium state, for example, the standing operation time may be 0-10 hours.
- Select a charging rate for example, select a preset charging rate, a first charging rate, a second charging rate, or a third charging rate.
- the current value I, the voltage value V, the temperature value T and the pressure value F of the lithium battery can be recorded.
- the current value I, the voltage value V, the temperature value T and the pressure value F of the lithium battery can be recorded.
- step S907 a standstill operation; after that, return to step S903 to reselect the charging rate and continue to execute downward.
- a certain discharge rate can be used for the discharge operation when the lithium battery is vented, and the size of the discharge rate can be set by those skilled in the art according to the actual situation, which is not specifically limited in the embodiments of the present application.
- the time of the above-mentioned resting operation can also be set by those skilled in the art according to the actual situation, which is also not specifically limited in this embodiment of the present application.
- a device applying a lithium battery includes a corresponding hardware structure and/or software module for performing each function.
- a device applying a lithium battery includes a corresponding hardware structure and/or software module for performing each function.
- the present application can be implemented in hardware or a combination of hardware and computer software with the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein. Whether a function is performed by hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of this application.
- the functional modules of the lithium-evolution detection device of a lithium battery can be divided according to the above method examples.
- each functional module can be divided corresponding to each function, or two or more functions can be integrated into one module.
- the above-mentioned integrated modules can be implemented in the form of hardware, and can also be implemented in the form of software function modules.
- the division of modules in the embodiments of the present application is schematic, and is only a logical function division, and there may be other division manners in actual implementation. The following is an example of dividing each function module corresponding to each function as an example:
- FIG. 10 is a schematic structural diagram of a lithium-evolution detection device for a lithium battery provided by an embodiment of the present application.
- the device includes: a target parameter determination unit 1001 , a model determination unit 1002 , a diagnosis parameter acquisition unit 1003 , an analysis Lithium diagnosis unit 1004 , current control unit 1005 , and lithium deposition alarm unit 1006 .
- the lithium evolution detection device may be a BMS, or a chip integrated with the BMS.
- the target parameter determination unit 1001 , the diagnostic parameter acquisition unit 1003 , and the lithium evolution diagnostic unit 1004 may all be the lithium evolution in the BMS shown in FIG. 2 when specifically implemented.
- Security diagnostic module 204 .
- the current control unit 1005 may be the lithium deposition prevention management module 203 in the BMS shown in FIG. 2 .
- the lithium precipitation alarm unit 1006 may be the communication module 207 in the BMS shown in FIG. 2 in a specific implementation.
- the target parameter determination unit 1001 is configured to determine the target parameter corresponding to the lithium battery according to the battery state of health SOH of the lithium battery, the temperature of the lithium battery, and the corresponding relationship between the SOH of the lithium battery and the temperature of the lithium battery and the target parameter.
- the target parameter corresponding to the lithium battery is the ratio of the polarization voltage of the negative electrode of the lithium battery to the polarization voltage of the lithium battery, and the polarization voltage is the difference between the actual voltage and the open circuit voltage.
- the target parameter determination unit 1001 is further configured to use the preset charging rate, the first charging rate, the second charging rate, and the third charging rate for different temperatures and different SOH. charging the lithium battery.
- the preset charging rate to charge the lithium battery it is determined that the open circuit voltage OCV of the lithium battery corresponding to the SOC of the lithium battery under different battery states of charge and the OCV of the negative electrode of the lithium battery corresponding to the lithium battery under different SOC,
- the OCV of the negative electrode of the lithium battery is the reference potential of the negative electrode of the lithium battery relative to the lithium electrode.
- the corresponding temperature and pressure of the lithium battery under different SOC are obtained respectively, and the corresponding pressure of the lithium battery under different SOC is used for Indicates the change in the external expansion volume of the lithium battery during charging. Then, according to the corresponding temperature and pressure of the lithium battery under different SOCs, the corresponding lithium-evolution effect pressures of the lithium battery under different SOCs are determined, and the corresponding lithium-evolution effect pressures of the lithium battery under different SOCs are used to indicate that the lithium battery is formed by Pressure changes due to the lithium effect.
- the polarity of the negative electrode of the lithium battery is determined. polarization voltage and polarization voltage of lithium batteries.
- the corresponding temperatures and pressures of the lithium battery under different SOCs include a first temperature and a first pressure corresponding to the first charging rate, and a second temperature and a second charging rate corresponding to the second charging rate. pressure, and a third pressure corresponding to the third charging rate.
- the first pressure is the total pressure caused by the occurrence of lithium ion deintercalation effect, temperature effect and lithium precipitation effect
- the second pressure is the total pressure caused by the occurrence of lithium ion deintercalation effect and temperature effect
- the third pressure is the occurrence of lithium ion deintercalation effect. Stress due to ion deintercalation effects.
- the target parameter determination unit 1001 is specifically configured to: determine the temperature effect of the lithium battery between the pressure and the temperature according to the difference between the second pressure and the third pressure and the second temperature under different SOCs association relationship.
- the temperature effect pressure of the lithium battery is used to indicate the pressure change of the lithium battery caused by the temperature effect at different temperatures.
- the corresponding temperature effect pressure of the lithium battery under different SOCs is determined.
- the difference between the sum of the temperature effect pressure and the third pressure corresponding to the lithium battery at different SOCs and the first pressure is determined as the lithium evolution effect pressure corresponding to the lithium battery at different SOCs.
- the target parameter determination unit 1001 is specifically configured to: determine the OCV of the negative electrode of the lithium battery corresponding to the initial SOC as the polarization voltage of the negative electrode of the lithium battery, wherein the initial SOC is the The corresponding SOC when the pressure value of the lithium effect pressure transitions from zero to non-zero.
- the difference between the OCV of the lithium battery and the (actual) voltage of the lithium battery corresponding to the termination SOC is determined as the polarization voltage of the lithium battery, wherein the termination SOC is the SOC corresponding to the maximum pressure value of the lithium precipitation effect pressure.
- the preset lithium precipitation estimation model is Among them, I is the charging current of the lithium battery, Q is the rated power of the lithium battery, ⁇ Idt is the electric capacity of the lithium battery at the current moment, SOC is the battery state of charge of the lithium battery, and V neg is the real-time potential value of the negative electrode of the lithium battery , OCV neg is the open circuit voltage of the negative electrode of the lithium battery, V p,neg is the polarization voltage of the negative electrode of the lithium battery, T is the temperature of the lithium battery, SOH is the battery state of health of the lithium battery, OCV neg (SOC, T, SOH ) is the function of OCV neg on SOC, T, SOH, ⁇ is the target parameter in the lithium-evolution estimation model of lithium battery, V cell is the voltage of lithium battery, OCV cell (SOC, T, SOH) is the relationship between SOC, T, SOH of OCV cell A function of T and SOH, V cell -OCV cell (SOC, T),
- the model determination unit 1002 is used for substituting target parameters corresponding to the lithium battery into the preset lithium evolution estimation model to obtain the lithium evolution estimation model of the lithium battery.
- the diagnostic parameter acquisition unit 1003 is used to input the charging current of the lithium battery, the voltage of the lithium battery, the temperature of the lithium battery and the SOH of the lithium battery into the lithium precipitation estimation model of the lithium battery, and obtain the real-time data of the negative electrode of the lithium battery. potential value.
- the lithium precipitation diagnosis unit 1004 is configured to determine that lithium precipitation occurs in the lithium battery if the real-time potential value of the negative electrode of the lithium battery is less than zero.
- the lithium precipitation alarm unit 1006 is configured to output the lithium precipitation alarm information, and the lithium precipitation alarm information includes the lithium precipitation occurrence time, the lithium precipitation termination time, the SOC corresponding to the lithium precipitation occurrence time, and the lithium precipitation alarm information. and at least one item in the severity level of lithium precipitation, where the severity level of lithium precipitation is determined according to the duration of lithium precipitation and the real-time potential value of the negative electrode.
- the current control unit 1005 is configured to adjust the charging current of the lithium battery according to the real-time potential value of the negative electrode.
- the current control unit 1005 is further configured to determine the maximum safe charging current of the lithium battery according to the time when the lithium precipitation occurs and the SOC corresponding to the time when the lithium precipitation occurs.
- an embodiment of the present application further provides a device for applying a lithium battery, the device including a lithium battery, a charging and discharging device, and the lithium deposition detection device shown in FIG. 10 .
- the lithium evolution detection device is used to perform the relevant steps in the method examples provided above, for example, the lithium evolution detection device is used to perform S301-S304 in the above method examples, or the above method examples In the S401-S406 or S901-S907 and so on.
- Units described as separate components may or may not be physically separated, and components shown as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.
- each functional unit in each embodiment of the embodiments of the present application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.
- the functions, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer-readable storage medium.
- the technical solutions of the embodiments of the present application can be embodied in the form of software products in essence, or the parts that make contributions to the prior art or the parts of the technical solutions, and the computer software products are stored in a storage medium , including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in the various embodiments of the present application.
- the aforementioned storage medium includes: U disk, mobile hard disk, Read-Only Memory (ROM, Read-Only Memory), Random Access Memory (RAM, Random Access Memory), magnetic disk or optical disk and other media that can store program codes .
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Abstract
一种锂电池的析锂检测方法及装置,属于电池技术领域,可以应用在新能源汽车、电动汽车、智能汽车、网联汽车上,以提高析锂诊断的可靠性。该方法包括:根据锂电池的电池健康状态SOH、锂电池的温度,以及锂电池的SOH和锂电池的温度与目标参数的对应关系,确定锂电池对应的目标参数(S301);将锂电池对应的目标参数代入预设析锂估算模型中,得到锂电池的析锂估算模型(S302);将锂电池的充电电流、锂电池的电压、锂电池的温度和锂电池的SOH输入锂电池的析锂估算模型,得到该锂电池的负极的实时电位值(S303);若该锂电池的负极的实时电位值小于零,则确定该锂电池发生析锂(S304)。
Description
本申请涉及电池技术领域,可以应用在新能源汽车、电动汽车、智能汽车、网联汽车上,尤其涉及一种锂电池的析锂检测方法及装置。
锂电池因其污染小、能量密度高、循环寿命长和自放电率低等优点,被广泛应用在手机、平板电脑、便携式设备等电子设备上,以及电动汽车、电动摩托车等各种电动车辆上,成为这些设备或车辆中不可或缺的部件。因此,关于锂电池的安全性的问题受到人们越来越多的关注,析锂作为锂电池在充电过程中的一种异常现象,是近年来人们关注的热点问题之一。
在对锂电池充电的过程中,锂离子会从正极脱嵌并嵌入负极。当从正极脱嵌的锂离子无法嵌入负极时,这些锂离子会析出在负极表面,形成金属锂,这就叫作析锂。析锂发生的条件可以分为内部因素和外部因素两种。内部因素通常包括负极对锂电位小于0,这样导致锂离子不再全部嵌入负极,而是一部分嵌入负极,一部分以锂金属态析出。外部因素通常包括低温、高电荷状态(state of charge,SOC)和高倍率充电。其中,低温会造成锂离子扩散动力变慢,高电荷状态时的负极对锂电位相对较低,从而低温和高电荷状态都不利于锂离子嵌入负极;高倍率充电会生成较强电场推动大量锂离子从正极脱嵌并嵌入负极,当脱嵌的锂离子数量大于负极能够接收的锂离子数量时就会导致析锂产生。
析锂的发生和累积会降低库伦效率,导致锂电池的容量降低,析出的锂金属容易造成负极膨胀和颗粒破裂,使更多负极新鲜界面暴露在电解液中形成新的固体电解质界面(solid electrolyte interface,SEI)膜,导致阻抗的增加。另外,析出的锂金属持续生长会引发锂枝晶的形成,进而诱发内部短路带来安全风险,析出的锂金属也会与电解液缓慢反应,大大降低热失控的起始温度。因此,存在锂电池的析锂检测需求。
现有技术中,对于目前的实时析锂检测技术,析锂检测方法为:在对锂电池充电的过程中,监测锂电池的充电电压和荷电状态,该充电电压作为第一电压;从预设的开路电压与荷电状态之间对应关系中,获取当前荷电状态所对应的电压值作为第二电压;根据第一电压与第二电压的差值(即极化电压)与事先测量得到的极化电压阈值的大小关系,判断充电过程中是否发生析锂,若该差值大于极化电压阈值,则可确定该锂电池发生了析锂。但是,该方法中的锂电池的极化电压不能区分正负极极化电压,而析锂主要发生在锂电池的负极。因此通过锂电池的极化电压和极化电压阈值来确定锂电池是否发生析锂,可能会使得析锂检测的可靠性较低。
发明内容
本申请提供一种锂电池的析锂检测方法及装置,根据锂电池的电压、锂电池的充电电流、锂电池的温度、锂电池的SOH,以及锂电池的温度、SOH与目标参数的对应关系,确定锂电池的析锂估算模型,进而确定锂电池的负极实时电位值,以使得本申请可以根据该负极实时电位值对锂电池是否发生析锂进行检测,提高析锂检测的可靠性。
为达到上述目的,本申请的实施例采用如下技术方案:
第一方面,提供一种锂电池的析锂检测方法,包括:根据锂电池的电池健康状态SOH和(锂电池的)温度,以及锂电池的温度、SOH与目标参数的对应关系,确定该锂电池对应的目标参数。将该锂电池对应的目标参数代入预设析锂估算模型中,从而得到该锂电池的析锂估算模型。随后,将锂电池的充电电流、电压、温度和SOH输入到该锂电池的析锂估算模型中,得到该锂电池的负极的实时电位值。若利用上述析锂估算模型所得锂电池的负极的实时电位值小于零,则确定该锂电池发生析锂。
其中,该锂电池对应的目标参数为该锂电池的负极的极化电压与该锂电池的极化电压的比值,极化电压为实际电压与开路电压的差值。更具体的,锂电池的负极的极化电压为该锂电池的负极的实际电压与该锂电池的负极的开路电压的差值,锂电池的极化电压为该锂电池的实际电压与该锂电池的开路电压的差值。
一般的,锂电池发生析锂或者结束析锂时,其负极的电位值为零,且析锂发生在负极,相对于锂电池的极化电压等其他数据来说,负极的实时电位值可以更直接和准确地反映锂电池的负极状态(即锂电池是否发生析锂)。因此,通过对锂电池的负极实时电位值是否小于零进行判断,可以较直接准确地确定锂电池是否发生了析锂,提高析锂检测的可靠性。另外,在不对锂电池进行改造或拆解的情况下,可以根据锂电池的温度和SOH与目标参数的对应关系,确定该锂电池的析锂估算模型中的目标参数,从而可以直接根据锂电池的温度、SOH、充电电流、电压和锂电池的析锂估算模型,获取到锂电池的实时负极电位值,以在保证析锂检测的可靠性的同时,简化析锂检测的过程,提高析锂检测的效率。
在第一方面的一种可能的实现方式中,在根据锂电池的SOH、锂电池的温度,以及锂电池的SOH和锂电池的温度与目标参数的对应关系,确定锂电池对应的目标参数之前,需要先确定锂电池的SOH和锂电池的温度与目标参数的对应关系,包括:使用预设充电倍率、第一充电倍率、第二充电倍率、第三充电倍率对不同温度、不同SOH的锂电池充电。使用预设充电倍率对锂电池充电的过程中,确定锂电池在不同电池荷电状态SOC对应的锂电池的开路电压OCV以及锂电池在不同的SOC下对应的锂电池的负极的OCV,该锂电池的负极的OCV为该负极相对于锂电极的参比电位。在使用第一充电倍率、第二充电倍率或第三充电倍率对锂电池充电的过程中,分别获取锂电池在不同SOC下对应的温度和压力,该压力用于指示锂电池在充电过程中的外部膨胀体积的变化。随后,根据锂电池在不同SOC下对应的温度和压力,确定锂电池在不同SOC下对应的析锂效应压力,该锂电池在不同SOC下对应的析锂效应压力用于指示该锂电池由析锂效应导致的压力变化。根据锂电池在不同SOC对应的锂电池的OCV、锂电池在不同的SOC下对应的锂电池的负极的OCV和锂电池在不同SOC下对应的析锂效应压力,确定锂电池的负极的极化电压以及锂电池的极化电压。最后,建立锂电池的温度、锂电池的SOH与目标参数的对应关系。该目标参数,即为锂电池的负极的极化电压与锂电池的极化电压的比值。
一般的,传统的电流、电压、温度等信息表征锂电池发生析锂的灵敏度较低。锂电池的析锂量较多时,该电流、电压和温度等信息才会发生较为明显的变化,以表征该锂电池发生了析锂。相对于利用上述传统的电流、电压、温度等信息来表征锂电池是否发生析锂,利用析锂效应压力来表征锂电池是否发生析锂的灵敏度较高,用于析锂检测的可靠性也较高。且锂电池的极化电压和锂电池的负极的极化电压是通过对析锂结束时和析锂开始时的锂电池的电压、锂电池的负极的电压、锂电池的负极的OCV以及锂电池的 OCV进行处理得到的。由于利用析锂效应压力所确定的析锂结束时刻和析锂开始时刻的准确性较高,根据该析锂结束时刻和析锂开始时刻对应的电压和开路电压,确定锂电池的负极的极化电压以及该锂电池的极化电压的准确性较高,所得该锂电池的析锂估算模型的析锂检测的可靠性较高。
在第一方面的一种可能的实现方式中,锂电池在不同SOC下对应的温度和压力包括与第一充电倍率对应的第一温度和第一压力,与第二充电倍率对应的第二温度和第二压力,以及与第三充电倍率对应的第三压力。其中,第一压力为发生锂离子脱嵌效应、温度效应和析锂效应所导致的总压力,第二压力为发生锂离子脱嵌效应、温度效应所导致的总压力,第三压力为发生锂离子脱嵌效应所导致的压力。
在第一方面的一种可能的实现方式中,根据不同SOC下第二压力和第三压力的差值、以及第二温度,确定锂电池的温度效应压力与温度之间的关联关系。该锂电池的温度效应压力用于指示锂电池在不同温度下由温度效应导致的压力变化。根据第一温度与上述关联关系,确定在使用第一充电倍率对锂电池充电的过程中,锂电池在不同SOC下对应的温度效应压力。最后,将锂电池在不同SOC下对应的温度效应压力和第三压力之和与第一压力的差值,确定为锂电池在不同SOC下对应的析锂效应压力。
上述可能的实现方式中,通过检测不同充电倍率下锂电池的压力值,可得到不同充电倍率下锂电池的不同SOC与压力值的关系,以及锂电池所受温度效应压力与温度之间的关联关系,从而根据第一压力和第一温度,通过减去锂离子脱嵌效应和温度效应所引起的压力值的变化,简单、有效的确定锂电池所受的析锂效应压力。其次,由于析锂效应压力是由于锂电池发生析锂所产生的压力,也就是说,锂电池未发生析锂时,锂电池所受析锂效应压力为零。因此,基于该析锂效应压力可以在锂电池充电过程中有效地检测锂电池的析锂情况,且相对于上述传统的电流、电压、温度等信息,利用析锂效应压力来确定锂电池是否发生析锂的灵敏度较高,析锂检测的可靠性也较高。
在第一方面的一种可能的实现方式中,将起始SOC对应的锂电池的负极的OCV,确定为负极的极化电压,其中,起始SOC即析锂效应压力的压力值从零转折为非零时对应的SOC。将终止SOC对应的锂电池的OCV与锂电池的(实际)电压的差值,确定为锂电池的极化电压,其中,该终止SOC即为析锂效应压力的最大压力值对应的SOC。
上述可能的实现方式中,析锂效应压力为零时,用于指示锂电池发生析锂效应,因此,可以将析锂效应压力中压力值从零转折为非零时对应的SOC确定为锂电池发生析锂的起始SOC,实现对析锂的起始点的准确检测。且上述可能的实现方式中,析锂效应压力为锂电池充电过程中的最大值时,用于指示该锂电池的析锂效应结束,因此,可以将析锂效应压力中最大压力值对应的SOC确定为锂电池发生析锂的终止SOC,实现对析锂的终止SOC的准确检测。
在第一方面的一种可能的实现方式中,预设析锂估算模型为
其中,I为锂电池的充电电流,Q为锂电池的额定电量,∫
Idt表示锂电池在当前时刻的电容量,SOC为锂电池的电池荷电状态,V
neg为锂电池的负极实时电位值,OCV
neg为锂电池的负极的开路电压,V
p,neg为锂电池的负极的极化电压,T为锂电池的温度,SOH为锂电池的电池健康状态,OCV
neg(SOC,T,SOH)为OCV
neg关于SOC、T、SOH的函数,α为析锂估算模型中的目标参数,V
cell为锂电池的电压,OCV
cell(SOC,T,SOH)为OCV
cell关于SOC、T、SOH的函数,V
cell-OCV
cell(SOC,T,SOH)表示锂电池的极化电压。
通过将锂电池的充电电流、电压、SOH、和温度,输入根据该预设析锂估算模型得到的该锂电池的析锂估算模型中,得到该锂电池的负极的实时电位值,从而在不破坏电池完整性的前提下,根据与该锂电池的析锂直接相关的其负极的实时电位值,确定锂电池是否发生析锂,保证锂电池析锂检测的可靠性。
在第一方面的一种可能的实现方式中,确定锂电池发生析锂后,输出析锂告警信息,该析锂告警信息包括析锂发生时刻、析锂终止时刻、析锂发生时刻对应的SOC、以及析锂严重等级中至少一项,该析锂严重等级是根据析锂持续时长以及负极的实时电位值确定的。
在第一方面的一种可能的实现方式中,该方法还包括:根据锂电池的负极的实时电位值,调节该锂电池的充电电流。
上述可能的实现方式中,在使用不同充电电流对锂电池进行充电时,可以根据该锂电池的负极的实时电位值,确定使用当前充电电流进行充电时该锂电池是否发生析锂,若确定该锂电池发生析锂,则可以调节当前充电电流的大小,比如减小当前充电电流,从而避免使该锂电池逐渐远离析锂状态,转为安全充电状态,确保该锂电池在充电过程中的安全性。
在第一方面的一种可能的实现方式中,该方法还包括:根据析锂发生时刻以及析锂发生时刻对应的SOC,确定锂电池的最大安全充电电流。
上述可能的实现方式中,在对锂电池进行充电时,可以根据不同条件下该锂电池所允许的最大安全充电电流调节充电电流,使充电电流恒处于安全的充电电流范围内,从而确保该锂电池在充电过程中的安全性。
在第一方面的一种可能的实现方式中,在使用预设充电倍率对锂电池充电的过程中,获取锂电池的OCV与其充电容量的对应关系、锂电池的负极的OCV与该负极的充电容量的对应关系,以及锂电池的正极的OCV与该正极的充电容量的对应关系。基于上述对应关系,对锂电池的电压和充电容量进行微分处理,得到锂电池的dV/dQ曲线,相类似的,获取到锂电池的负极的dV/dQ曲线以及锂电池的正极的dV/dQ曲线。随后,基于锂电池的dV/dQ曲线中的特征峰,对锂电池的负极的dV/dQ曲线和锂电池的正极的dV/dQ曲线进行平移或缩放处理,使得锂电池的负极的dV/dQ曲线的特征峰、锂电池的正极的dV/dQ曲线的特征峰与锂电池的dV/dQ曲线的特征峰对齐。根据特征峰对齐后的锂电池的负极的dV/dQ曲线和锂电池的dV/dQ曲线,获取到锂电池在不同的SOC对应的锂电池的OCV以及锂电池在不同的SOC下对应的其负极的OCV。
在第一方面的一种可能的实现方式中,在建立锂电池的SOH、温度与目标参数的对应关系后,存储该对应关系,以使得在后续的析锂诊断过程中,可以直接根据锂电池的SOH、温度,以及锂电池的SOH、温度与目标参数的对应关系,确定该锂电池的析锂估算模型中的目标参数,得到所需的锂电池的析锂估算模型。
第二方面,提供一种锂电池的析锂检测装置,包括:目标参数确定单元,用于根据锂电池的电池健康状态SOH、该锂电池的温度,以及锂电池的SOH和锂电池的温度与目标参数的对应关系,确定该锂电池对应的目标参数。该锂电池对应的目标参数为该锂电池的负极的极化电压与该锂电池的极化电压的比值,极化电压为实际电压与开路电压的差值。模型确定单元,用于将锂电池对应的目标参数代入预设析锂估算模型中,得到该锂电池的析锂估算模型。诊断参数获取单元,用于将锂电池的充电电流、锂电池的电压、该锂电池的温度和该锂电池的SOH输入该锂电池的析锂估算模型中,得到该锂电池的负极的实时电位值。析锂诊断单元,用于若该锂电池的负极的实时电位值小于零,则确定 该锂电池发生析锂。
在第二方面的一种可能的实现方式中,目标参数确定单元,还用于:使用预设充电倍率、第一充电倍率、第二充电倍率、第三充电倍率对不同温度、不同SOH的锂电池充电。在使用预设充电倍率对锂电池充电的过程中,确定锂电池在不同电池荷电状态SOC对应的锂电池的是开路电压OCV以及锂电池在不同的SOC下对应的锂电池的负极的OCV,该锂电池的负极的OCV为该锂电池的负极相对于锂电极的参比电位。在使用第一充电倍率、第二充电倍率或第三充电倍率对锂电池充电的过程中,分别获取锂电池在不同SOC下对应的温度和压力,该锂电池在不同SOC下对应的压力用于指示该锂电池在充电过程中的外部膨胀体积的变化。随后,根据锂电池在不同SOC下对应的温度和压力,确定锂电池在不同SOC下对应的析锂效应压力,该锂电池在不同SOC下对应的析锂效应压力用于指示该锂电池由析锂效应导致的压力变化。根据锂电池在不同SOC对应的锂电池的OCV、锂电池在不同的SOC下对应的该锂电池的负极的OCV和锂电池在不同SOC下对应的析锂效应压力,确定锂电池的负极的极化电压以及锂电池的极化电压。最后,建立锂电池的温度、锂电池的SOH和目标参数,即锂电池的负极的极化电压与锂电池的极化电压的比值,的对应关系。
在第二方面的一种可能的实现方式中,锂电池在不同SOC下对应的温度和压力包括与第一充电倍率对应的第一温度和第一压力,与第二充电倍率对应的第二温度和第二压力,以及与第三充电倍率对应的第三压力。其中,第一压力为发生锂离子脱嵌效应、温度效应和析锂效应所导致的总压力,第二压力为发生锂离子脱嵌效应、温度效应所导致的总压力,第三压力为发生锂离子脱嵌效应所导致的压力。
在第二方面的一种可能的实现方式中,目标参数确定单元,具体用于:根据不同SOC下第二压力和第三压力的差值、以及第二温度,确定锂电池的温度效应压力与温度之间的关联关系。该锂电池的温度效应压力用于指示该锂电池在不同温度下由温度效应导致的压力变化。根据第一温度和上述关联关系,确定在使用第一充电倍率对锂电池充电的过程中,该锂电池在不同SOC下对应的温度效应压力。最后,将该锂电池在不同SOC下对应的温度效应压力和第三压力之和与第一压力的差值,确定为该锂电池在不同SOC下对应的析锂效应压力。
在第二方面的一种可能的实现方式中,目标参数确定单元,具体用于:将起始SOC对应的锂电池的负极的OCV,确定为锂电池的负极的极化电压,其中,起始SOC即析锂效应压力的压力值从零转折为非零时对应的SOC。将终止SOC对应的锂电池的OCV与锂电池的(实际)电压的差值,确定为锂电池的极化电压,其中,该终止SOC即为析锂效应压力的最大压力值对应的SOC。
在第二方面的一种可能的实现方式中,预设析锂估算模型为
其中,I为锂电池的充电电流,Q为锂电池的额定电量,∫
Idt表示锂电池在当前时刻的电容量,SOC为锂电池的电池荷电状态,V
neg为锂电池的负极实时电位值,OCV
neg为锂电池的负极的开路电压,V
p,neg为锂电池的负极的极化电压,T为锂电池的温度,SOH为锂电池的电池健康状态,OCV
neg(SOC,T,SOH)为OCV
neg关于SOC、T、SOH的函数,α为析锂估算模型中的目标参数,V
cell为锂电池的电压,OCV
cell(SOC,T,SOH)为OCV
cell关于SOC、T、SOH的函数,V
cell-OCV
cell(SOC,T,SOH)表示锂电池的极化电压。
在第二方面的一种可能的实现方式中,该装置还包括析锂告警单元,确定锂电池发生析锂后,该析锂告警单元用于输出析锂告警信息,该析锂告警信息包括析锂发生时刻、析锂终止时刻、析锂发生时刻对应的SOC、以及析锂严重等级中至少一项,该析锂严重等级是根据 析锂持续时长以及锂电池的负极的实时电位值确定的。
在第二方面的一种可能的实现方式中,确定锂电池发生析锂后,输出析锂告警信息,该析锂告警信息包括析锂发生时刻、析锂终止时刻、析锂发生时刻对应的SOC、以及析锂严重等级中至少一项,该析锂严重等级是根据析锂持续时长以及负极的实时电位值确定的。
在第二方面的一种可能的实现方式中,该装置还包括电流控制单元,该电流控制单元,用于根据锂电池的负极的实时电位值,调节锂电池的充电电流。
在第二方面的一种可能的实现方式中,该装置还包括电流控制单元,该电流控制单元用于根据析锂发生时刻以及析锂发生时刻对应的SOC,确定锂电池的最大安全充电电流。
在第二方面的一种可能的实现方式中,目标参数确定单元,具体用于在使用预设充电倍率对锂电池充电的过程中,获取锂电池的OCV与其充电容量的对应关系、锂电池的负极的OCV与该负极的充电容量的对应关系,以及锂电池的正极的OCV与该正极的充电容量的对应关系。基于上述对应关系,对锂电池的电压和充电容量进行微分处理,得到锂电池的dV/dQ曲线,相类似的,可获取到锂电池的负极的dV/dQ曲线以及锂电池的正极的dV/dQ曲线。随后,基于锂电池的dV/dQ曲线中的特征峰,对锂电池的负极的dV/dQ曲线和锂电池的正极的dV/dQ曲线进行平移或缩放处理,使得锂电池的负极的dV/dQ曲线的特征峰、锂电池的正极的dV/dQ曲线的特征峰与锂电池的dV/dQ曲线的特征峰对齐。根据特征峰对齐后的锂电池的负极的dV/dQ曲线和锂电池的dV/dQ曲线,获取到锂电池在不同的SOC对应的锂电池的OCV以及锂电池在不同的SOC下对应的其负极的OCV。
在第二方面的一种可能的实现方式中,目标参数确定单元建立该SOH、温度和该目标参数的对应关系后,并存储该对应关系,以使得在后续的析锂诊断过程中,可以直接根据锂电池的SOH、温度,以及锂电池的SOH、温度与目标参数的对应关系,确定该锂电池的析锂估算模型中的目标参数,得到所需的锂电池的析锂估算模型。
第三方面,提供一种应用锂电池的设备,该设备包括锂电池、充放电单元、以及如上述第二方面或者第二方面的任一种可能的实现方式所提供的析锂检测装置等;其中,充放电单元用于对锂电池进行充电或放电,该装置用于控制充放电单元并执行第一方面或第一方面的任一种可能的实现方式所提供的方法。
其中,上述应用锂电池的设备可以是车辆,该车辆可以是智能汽车或者电动汽车(electric vehicle,EV)等。
在本申请的又一方面,提供一种计算机可读存储介质,所述计算机可读存储介质中存储有指令,当所述指令在设备上运行时,使得所述设备执行第一方面或者第一方面的任一种可能的实现方式所提供的锂电池的析锂检测方法。
在本申请的又一方面,提供一种计算机程序产品,所述计算机程序产品在设备上运行时,使得所述设备执行第一方面或者第一方面的任一种可能的实现方式所提供的锂电池的析锂检测方法。
可以理解地,上述提供的任一种锂电池的析锂检测方法的装置、设备、计算机可读存储介质和计算机程序产品均用于执行上文所提供的对应的方法,因此,其所能达到的有益效果可参考上文所提供的对应的方法中的有益效果,此处不再赘述。
图1为本申请实施例提供的一种车辆的结构示意图;
图2为本申请实施例提供的一种电池管理系统的结构示意图;
图3为本申请实施例提供的一种锂电池的析锂检测方法的流程示意图;
图4为本申请实施例提供的另一种锂电池的析锂检测方法的流程示意图;
图5(a)为本申请实施例提供的一种锂电池、锂电池正极和锂电池负极的OCV与SOC之间的对应关系的示意图;
图5(b)为本申请实施例提供的一种锂电池dV/dQ曲线、锂电池正极的dV/dQ曲线,以及锂电池负极的dV/dQ曲线的示意图;
图5(c)为本申请实施例提供的一种调整后的锂电池和锂电池负极的OCV与SOC之间的对应关系的示意图;
图6为本申请实施例提供的一种析锂效应所导致的压力值与SOC之间的关系示意图;
图7(a)为本申请实施例提供的一种锂电池在不同SOC下的负极实时电位的示意图一;
图7(b)为本申请实施例提供的一种锂电池在不同SOC下的负极实时电位的示意图二;
图7(c)为本申请实施例提供的一种锂电池在不同SOH下的循环充电次数的示意图;
图8为本申请实施例提供的一种测量锂电池的压力值的测量结构示意图;
图9为本申请实施例提供的一种锂电池充放电的流程示意图;
图10为本申请实施例提供的一种锂电池的析锂检测装置的结构示意图。
在介绍本申请实施例之前首先对本申请所涉及到的相关术语进行介绍说明。
充电倍率是充电快慢的一种量度,指电池在规定的时间充电至其额定容量时所需要的电流值,充电倍率在数值上等于电池额定容量的倍数,即充电倍率=充电电流/额定容量,通常以字母C表示,这里的“/”表示除法符号。比如,电池的额定容量为100安培小时(ampere hour,Ah),若充电电流为5安培(ampere,A)则充电倍率为0.05C,若充电电流为20A则充电倍率为0.2C,若充电电流为100A则充电倍率为1C。
放电倍率是放电快慢的一种量度,指电池在规定的时间内放出其额定容量时所需要的电流值,放电倍率在数值上等于电池额定容量的倍数,即放电倍率=放电电流/额定容量,通常以字母C表示。比如,电池的额定容量为100Ah,若放电电流为5A则放电倍率为0.05C,若放电电流为20A则放电倍率为0.2C,若放电电流为100A则放电倍率为1C。
库伦效率(coulombic efficiency),也叫放电效率,是指电池放电容量与同循环过程中充电容量之比,即放电容量与充电容量之百分比。对于正极材料来说,是嵌锂容量/脱锂容量,即放电容量/充电容量;对于负极材料来说,是脱锂容量/嵌锂容量,即放电容量/充电容量,这里的“/”表示除法符号。
电池荷电状态(state of charge,SOC)是用来反映电池的剩余容量状况的物理量,数值定义为电池剩余容量占电池容量的比值,即SOC=电池剩余容量/电池容量。SOC的取值范围为0~1,当SOC=0时表示电池放电完全,当SOC=1时表示电池完全充满。
电池健康状态(state of health,SOH)是用来反映电池的老化程度的物理量,数值定义为电池最大可用容量与电池额定容量的比值,即SOH=电池最大可用容量/电池额定容 量。SOC的取之范围为0~1,SOC的取值越大,则表示电池的健康状况越好,电池的老化程度越低。
锂电池,也可以称为锂离子电池,是一种二次电池,通常采用锂钴氧化物、锂镍氧化物或者锂锰氧化物等锂化合物作为电池的正极材料,采用石油焦炭或者石墨等碳材料作为电池的负极材料。锂电池主要依靠锂离子(Li+)在正极和负极之间的脱嵌和嵌入来工作。在充电过程中,锂离子从电池的正极脱嵌出来进入到电解液中,电解液中的锂离子嵌入负极。在放电过程中,嵌入负极的锂离子从负极脱出进入到电解液,电解液中的锂离子又嵌入至电池的正极。
锂离子脱嵌效应可以是指锂离子的脱嵌和嵌入过程所引起的锂电池的相关参数发生变化的特性。其中,锂离子从正极材料中脱嵌、并嵌入负极材料的过程会使锂电池的体积发生膨胀,这种体积变化会引起锂电池的压力的变化,本申请中将锂离子脱嵌和嵌入所产生的压力称为锂离子脱嵌效应所导致的压力。
温度效应可以是指在锂电池充电的过程中锂电池的温度变化所引起锂电池的相关参数发生变化的特性。其中,在对锂电池充电的过程中,锂电池的温度变化会引起锂电池发生热膨胀,这种热膨胀会产生锂电池的压力的变化,本申请中将温度变化所产生的压力称为温度效应所导致的压力。
析锂是指在锂电池充电的过程中,当从正极脱嵌的锂离子无法嵌入负极时,这些锂离子负极表面析出形成金属锂的过程。
析锂效应可以是指在锂电池充电的过程中负极析出的锂金属所引起的锂电池的相关参数发生变化的特性。其中,在对锂电池充电的过程中,负极析出的锂金属会引起锂电池的体积发生变化,析出的锂金属的量越大,体积变化越大,这种体积变化会产生锂电池的压力的变化,本申请中将析出的锂金属所产生的压力称为析锂效应所导致的压力。
为了便于清楚描述本申请实施例的技术方案,在本申请的实施例中,采用了“第一”、“第二”等字样对功能和作用基本相同的相同项或相似项进行区分。例如,第一阈值和第二阈值仅仅是为了区分不同的阈值,并不对其先后顺序进行限定。本领域技术人员可以理解“第一”、“第二”等字样并不对数量和执行次序进行限定,并且“第一”、“第二”等字样也并不限定一定不同。
需要说明的是,本申请中,“示例性的”或者“例如”等词用于表示作例子、例证或说明。本申请中被描述为“示例性的”或者“例如”的任何实施例或设计方案不应被解释为比其他实施例或设计方案更优选或更具优势。确切而言,使用“示例性的”或者“例如”等词旨在以具体方式呈现相关概念。
本申请中,“至少一个”是指一个或者多个,“多个”是指两个或两个以上。“和/或”,描述关联对象的关联关系,表示可以存在三种关系,例如,A和/或B,可以表示:单独存在A,同时存在A和B,单独存在B的情况,其中A,B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。“以下至少一项(个)”或其类似表达,是指的这些项中的任意组合,包括单项(个)或复数项(个)的任意组合。例如,a,b或c中的至少一项(个),可以表示:a,b,c,a和b的结合,a和c的结合,b和c的结合,或a、b和c的结合,其中a,b,c可以是单个,也可以是多个。
本申请实施例提供的方法可用于检测各种形式的锂电池。在一种可行的实施例中,本申请中的锂电池可以为铝壳锂电池、钢壳锂电池或者软包电池等;在另一种可行的实施例中,本申请中的锂电池可以为两电极电池或者三电极电池等;在又一种可行的实施 例中,本申请中的锂电池可以为电芯、电池模组或者电池包等。
另外,本申请实施例提供的方法可应用于使用锂电池的各种设备中,锂电池在不同的设备中可以作为储能器件,也可以作为动力器件。各种设备可以包括手机、平板电脑、可穿戴设备、车载终端等各种终端设备中,也可以包括轿车、卡车、摩托车、公交车、飞机等各种车辆中,还可以应用在基站、移动台和卫星等通信设备中。
下面以车辆为例,对应用本申请所提供的方法的设备的结构进行举例说明。
图1为本申请实施例提供的一种具有自动驾驶功能的车辆100的功能框图。在一个实施例中,将车辆100配置为完全或部分地自动驾驶模式。例如,车辆100可以在处于自动驾驶模式中同时控制自身的驾驶状态,并且可通过人为操作来确定车辆及其周边环境的当前状态,确定周边环境中的至少一个其他车辆的可能行为,并确定其他车辆执行可能行为的可能性,基于所确定的信息来控制车辆100。在车辆100处于自动驾驶模式中时,可以将车辆100置为在没有和人交互的情况下操作。
参见图1,车辆100可包括各种子系统,例如行进系统102、传感器系统104、控制系统106、一个或多个外围设备108以及电源110、计算机系统112和用户接口116。可选地,车辆100可包括更多或更少的子系统,并且每个子系统可包括多个元件。另外,车辆100的每个子系统和元件可以通过有线或者无线互连。
行进系统102可包括为车辆100提供动力运动的组件。在一个实施例中,行进系统102可包括引擎118、能量源119、传动装置120和车轮121。引擎118可以是内燃引擎、电动机、空气压缩引擎或其他类型的引擎组合,例如汽油发动机和电动机组成的混动引擎,内燃引擎和空气压缩引擎组成的混动引擎。引擎118将能量源119转换成机械能量。
能量源119的示例包括汽油、柴油、其他基于石油的燃料、丙烷、其他基于压缩气体的燃料、乙醇、太阳能电池板、电池和其他电力来源。能量源119也可以为车辆100的其他系统提供能量。
传动装置120可以将来自引擎118的机械动力传送到车轮121。传动装置120可包括变速箱、差速器和驱动轴。在一个实施例中,传动装置120还可以包括其他器件,比如离合器。其中,驱动轴可包括可耦合到一个或多个车轮121的一个或多个轴。
传感器系统104可包括感测关于车辆100周边的环境的信息的若干个传感器。例如,传感器系统104可包括定位系统122(例如,定位系统可以是全球定位系统(global positioning system,GPS)系统,也可以是北斗系统或者其他定位系统)、惯性测量单元(inertial measurement unit,IMU)124、雷达126、激光测距仪128以及相机130。传感器系统104还可包括被监视车辆100的内部系统的传感器(例如,车内空气质量监测器、燃油量表、机油温度表等)。来自这些传感器中的一个或多个的传感器数据可用于检测对象及其相应特性(位置、形状、方向、速度等)。这种检测和识别是自主车辆100的安全操作的关键功能。在本申请实施例中,传感器系统104可用于测量电池的温度和体积膨胀压力等状态参数。
定位系统122可用于估计车辆100的地理位置。IMU 124用于基于惯性加速度来感测车辆100的位置和朝向变化。在一个实施例中,IMU 124可以是加速度计和陀螺仪的组合。
雷达126可利用无线电信号来感测车辆100的周边环境内的物体。在一些实施例中,除了感测物体以外,雷达126还可用于感测物体的速度和/或前进方向。
激光测距仪128可利用激光来感测车辆100所位于的环境中的物体。在一些实施例中,激光测距仪128可包括一个或多个激光源、激光扫描器以及一个或多个检测器,以及其他系统组件。
相机130可用于捕捉车辆100的周边环境的多个图像。相机130可以是静态相机或视频相机。
控制系统106为控制车辆100及其组件的操作。控制系统106可包括多种元件,其中包括转向系统132、油门134、制动单元136、传感器融合算法138、计算机视觉系统140、路线控制系统142以及障碍规避系统144,其中,障碍规避系统144也可以称为障碍物避免系统。
转向系统132可操作来调整车辆100的前进方向。例如在一个实施例中,转向系统132可以为方向盘系统。
油门134用于控制引擎118的操作速度,并进而控制车辆100的速度。
制动单元136用于控制车辆100减速。制动单元136可使用摩擦力来减慢车轮121。在其他实施例中,制动单元136可将车轮121的动能转换为电流。制动单元136也可采取其他形式来减慢车轮121转速从而控制车辆100的速度。
计算机视觉系统140可以操作来处理和分析由相机130捕捉的图像以便识别车辆100周边环境中的物体和/或特征。所述物体和/或特征可包括交通信号、道路边界和障碍物。计算机视觉系统140可使用物体识别算法、运动中恢复结构(structure from motion,SFM)算法、视频跟踪和其他计算机视觉技术。在一些实施例中,计算机视觉系统140可以用于为环境绘制地图、跟踪物体、估计物体的速度等等。
路线控制系统142用于确定车辆100的行驶路线。在一些实施例中,路线控制系统142可结合来自传感器融合算法138、定位系统122和一个或多个预定地图的数据以为车辆100确定行驶路线。
障碍规避系统144用于识别、评估和避免或者以其他方式越过车辆100的环境中的潜在障碍物。
应理解,控制系统106可以增加或替换地包括除了所示出和描述的那些以外的组件。或者也可以减少一部分上述示出的组件。
车辆100通过外围设备108与外部传感器、其他车辆、其他计算机系统或用户之间进行交互。外围设备108可包括无线通信系统146、车载电脑148、麦克风150和/或扬声器152。
在一些实施例中,外围设备108提供车辆100的用户与用户接口116交互的手段。例如,车载电脑148可向车辆100的用户提供信息。用户接口116还可操作车载电脑148来接收用户的输入。车载电脑148可以通过触摸屏进行操作。在其他情况中,外围设备108可提供用于车辆100与位于车内的其它设备通信的手段。例如,麦克风150可从车辆100的用户接收音频(例如,语音命令或其他音频输入)。类似地,扬声器152可向车辆100的用户输出音频。
无线通信系统146可以直接地或者经由通信网络来与一个或多个设备无线通信。在本申请实施例中,无线通信系统146可包括车载智能终端(Telematics BOX,T-Box),T-Box可以安装在车辆100内部人手不容易触及的地方,比如仪表板下面,手套箱下面或者是后背箱下面等。T-Box可主要用于负责车辆100与车联网服务平台之间的通信。例如,T-Box可使用3G蜂窝通信,例如码分多址(code division multiple access,CDMA)、全球移动通信系统(global system for mobile communications,GSM)、通用分组无线服务(general packet radio service,GPRS)技术,或者4G蜂窝通信,例如长期演进(long term evolution,LTE),或者5G蜂窝通信。无线通信系统146可利用WiFi与无线局域网(wireless local area network,WLAN)通信。在一些实施例中,无线通信系统146可利用红外链路、蓝牙或ZigBee与设备直接通信。其他无线协议,例如各种车辆通信系统,例如,无线通信系统146可包括一个或多个专用短 程通信(dedicated short range communications,DSRC)设备,这些设备可包括车辆和/或路边台站之间的公共和/或私有数据通信。
电源110可向车辆100的各种组件提供电力。在一个实施例中,电源110可以为可再充电锂离子电池或可再充电铅酸电池。这种电池的一个或多个电池组可被配置为电源为车辆100的各种组件提供电力。在一些实施例中,电源110和能量源119可一起实现,例如全电动车。
车辆100的部分或所有功能受计算机系统112控制。计算机系统112可包括至少一个处理器123,处理器123执行存储在例如存储器114这样的非暂态计算机可读介质中的指令125。计算机系统112还可以是采用分布式方式控制车辆100的个体组件或子系统的多个计算设备。
处理器123可以是任何常规的处理器,诸如商业可获得的中央处理器(central processing unit,CPU)。替选地,该处理器可以是诸如专用集成电路(application specific integrated circuits,ASIC)或其它基于硬件的处理器的专用设备。
尽管图1功能性地图示了处理器、存储器、和在相同块中的计算机系统112的其它元件,但是本领域的普通技术人员应该理解该处理器、计算机、或存储器实际上可以包括可以或者可以不存储在相同的物理外壳内的多个处理器、计算机、或存储器。例如,存储器可以是硬盘驱动器或位于不同于计算机系统112的外壳内的其它存储介质。因此,对处理器或计算机的引用将被理解为包括对可以或者可以不并行操作的处理器或计算机或存储器的集合的引用。不同于使用单一的处理器来执行此处所描述的步骤,诸如转向组件和减速组件的一些组件每个都可以具有其自己的处理器,所述处理器只执行与特定于组件的功能相关的计算。
在一些实施例中,存储器114可包含指令125(例如,程序逻辑),指令125可被处理器123执行来执行车辆100的各种功能,包括以上描述的那些功能。存储器114也可包含额外的指令,包括向行进系统102、传感器系统104、控制系统106和外围设备108中的一个或多个发送数据、从其接收数据、与其交互和/或对其进行控制的指令。
除了指令125以外,存储器114还可存储数据,例如道路地图、路线信息,车辆的位置、方向、速度以及其它这样的车辆数据,以及其他信息。这种信息可在车辆100在自主、半自主和/或手动模式中操作期间被车辆100和计算机系统112使用。
用户接口116,用于向车辆100的用户提供信息或从其接收信息。可选地,用户接口116可包括在外围设备108的集合内的一个或多个输入/输出设备,例如无线通信系统146、车载电脑148、麦克风150和扬声器152。
计算机系统112可基于从各种子系统(例如,行进系统102、传感器系统104和控制系统106)以及从用户接口116接收的输入来控制车辆100的功能。例如,计算机系统112可利用来自控制系统106的输入以便控制转向系统132来避免由传感器系统104和障碍规避系统144检测到的障碍物。在一些实施例中,计算机系统112可操作来对车辆100及其子系统的许多方面提供控制。比如,计算机系统112中可以包括电池管理系统(battery management system,BMS),该BMS可用于管理电源110,具体可用于管理锂离子电池。通常情况下,BMS具有测量电池电压的功能,可以防止或避免电池过放电、过充电、或者过温度等异常情况的出现。
可选地,上述这些组件中的一个或多个可与车辆100分开安装,分开安装的组件与车辆100之间相关联。例如,存储器124可以部分或完全地与车辆100分开存在。上述组件可以按有线和/或无线方式来通信地耦合在一起,这里通信地耦合在一起是指耦合在一起的多个组件之间可以进行通信。
可选地,上述组件只是一个示例,实际应用中,上述各个模块中的组件有可能根据实际 需要增添或者删除,图1不应理解为对本申请实施例的限制。
在道路行进的自动驾驶汽车,如上面的车辆100,可以识别其周围环境内的物体以确定对当前速度的调整。所述物体可以是其它车辆、交通控制设备、或者其它类型的物体。在一些示例中,可以独立地考虑每个识别的物体,并且基于物体的各自的特性,诸如它的当前速度、加速度、与车辆的间距等,可以用来确定自动驾驶汽车所要调整的速度。
可选地,自动驾驶汽车车辆100或者与自动驾驶车辆100相关联的计算设备(如图1的计算机系统112、计算机视觉系统140、存储器114)可以基于所识别的物体的特性和周围环境的状态(例如,交通、雨、道路上的冰、等等)来预测所述识别的物体的行为。可选地,每一个所识别的物体都依赖于彼此的行为,因此还可以将所识别的所有物体全部一起考虑来预测单个识别的物体的行为。车辆100能够基于预测的所述识别的物体的行为来调整它的速度。换句话说,自动驾驶汽车能够基于所预测的物体的行为来确定车辆将需要调整到(例如,加速、减速、或者停止)什么稳定状态。在这个过程中,也可以考虑其它因素来确定车辆100的速度,诸如,车辆100在行驶的道路中的横向位置、道路的曲率、静态和动态物体的接近度等等。
除了提供调整自动驾驶汽车的速度的指令之外,计算设备还可以提供修改车辆100的转向角的指令,以使得自动驾驶汽车遵循给定的轨迹和/或维持与自动驾驶汽车附近的物体(例如,道路上的相邻车道中的轿车)的安全横向和纵向距离。
上述车辆100可以为轿车、卡车、摩托车、公共汽车、船、飞机、直升飞机、割草机、娱乐车、游乐场车辆、施工设备、电车、高尔夫球车、火车和手推车等,本申请实施例不做特别的限定。
在介绍完上述车辆100之后,下面对本申请涉及的上述车辆100中的BMS进行介绍说明。应理解的是,本申请实施例可以适用于其他终端的BMS中,例如手机、平板电脑、摄像机、计算机、上网本、超级移动个人计算机(ultra-mobile personal computer,UMPC)、可穿戴设备(比如,智能手环和智能手表等)、车载设备或便携式设备等。
图2为本申请实施例提供的一种电池管理系统BMS的结构示意图,该BMS可以包括:数据采集模块201、状态估计模块202、防析锂管理模块203、析锂安全诊断模块204、信息记录模块205、电池均衡模块206和通信模块207。
其中,数据采集模块201可用于采集锂电池的相关参数信息,比如数据采集模块201可以包括:电压传感器、电流传感器、温度传感器和压力传感器,分别用于采集锂电池的电压、电流、温度和压力等参数信息。状态估计模块202可用于估计锂电池的相关状态,比如状态估计模块202可用于估计锂电池的剩余寿命、锂电池是否处于安全状态等。防析锂管理模块203可用于管理锂电池在不同条件下充电时所允许的最大充电电流阈值,进而根据不同条件下的最大充电电流阈值控制充放电单元的充电电流等参数。析锂安全诊断模块204可用于诊断锂电池是否发生析锂,以及析锂发生的起始点和终止点等。信息记录模块205可用于记录锂电池的相关参数,比如锂电池的电流、电压、温度和压力等。电池均衡模块206可用于对锂电池进行均衡处理,比如用于均衡处理锂电池的电压偏差,以使该电压偏差在一定的范围内等。通信模块207可用于实现BMS与其他设备或单元之间的通信,比如可用于实现BMS与充放电单元之间的通信等。
需要说明的是,上述BMS中的各个模块均可以由硬件来实现,也可以由软件来实现,或者由硬件和软件的结合来实现,具体某个模块究竟以硬件、软件、或者软硬件结合的方式来实现,取决于技术方案的特定应用和设计约束条件,本申请实施例对此不作具体限 定。
为了保证锂电池析锂检测的可靠性,本申请实施例提供一种锂电池的析锂检测方法,该方法可应用于使用锂电池的各种设备中,比如应用于图1所示的车辆100中,具体可以由BMS执行或由处理器执行,其中,BMS和处理器可以设置于车辆100内,也可以设置于车辆100外。如图3所示,该方法包括以下步骤S301-S304:
S301、根据锂电池的电池健康状态SOH、锂电池的温度,以及锂电池的SOH和锂电池的温度与目标参数的对应关系,确定该锂电池对应的目标参数。
其中,锂电池对应的目标参数为该锂电池的负极的极化电压与该锂电池的极化电压的比值。极化电压为实际电压与开路电压的差值。也就是说,锂电池的负极的极化电压为该锂电池的负极的实际电压与该锂电池的负极的开路电压的差值,锂电池的极化电压为该锂电池的实际电压与该锂电池的开路电压的差值。
可选的,锂电池的SOH、锂电池的温度与目标参数存在对应关系,该对应关系可以以表格等形式存储。因此,在获取到锂电池的SOH和温度后,就可以确定该锂电池在当前状况下所对应的目标参数。
示例性的,锂电池的SOH、锂电池的温度与目标参数的对应关系可以如下表1所示。在不同的温度范围或不同SOH下的锂电池,所对应的目标参数α不同。若锂电池的温度和SOH满足-40℃<=T<10℃且0.8<SOH<=1的条件,则该锂电池所对应的目标参数为α
1;若锂电池的温度和SOH满足-10℃<=T<20℃且0.8<SOH<=1的条件,则该锂电池所对应的目标参数为α
2;若锂电池的温度和SOH满足-10℃<=T<20℃且0.6<SOH<=0.8的条件,则该锂电池所对应的目标参数为α
3。
表1
| 温度T | 电池健康状态SOH | 析锂估算模型的目标参数 |
| -40℃<=T<10℃ | 0.8<SOH<=1 | α 1 |
| -10℃<=T<20℃ | 0.8<SOH<=1 | α 2 |
| -10℃<=T<20℃ | 0.6<SOH<=0.8 | α 3 |
S302、将锂电池对应的目标参数代入预设析锂估算模型中,得到该锂电池的析锂估算模型。
其中,预设析锂估算模型为
I为锂电池的充电电流,Q为锂电池的额定容量,∫
Idt表示锂电池在当前时刻的容量,SOC为锂电池的电池荷电状态,V
neg为锂电池的负极实时电位值,OCV
neg为锂电池的负极的开路电压,V
p,neg为锂电池的负极的极化电压,T为(锂电池的)温度,SOH为锂电池的电池健康状态,OCV
neg(SOC,T,SOH)为OCV
neg关于SOC、T、SOH的函数,α为析锂估算模型中的目标参数,V
cell为锂电池的电压,OCV
cell(SOC,T,SOH)为OCV
cell关于SOC、T、SOH的函数,V
cell-OCV
cell(SOC,T,SOH)表示锂电池的极化电压。需要说明的是,析锂估算模型中的目标参数α为锂电池的负极的极化电压与该锂电池的极化电压的比值,SOC是根据锂电池的充电电流、充电时间和额定电量求得的,OCV
neg(SOC,T,SOH)表示OCV
neg的取值可以根据SOC、T和SOH的值进行计算或者查表等操作得到,OCV
cell(SOC,T,SOH)表示OCV
cell的取值可以根据SOC、T和SOH的值进行计算或者查表等操作得到。
S303、将锂电池的充电电流、锂电池的电压、锂电池的温度和锂电池的SOH输入该锂电池的析锂估算模型,得到该锂电池的负极的实时电位值。
获取锂电池的充电电流、锂电池的电压、锂电池的温度和锂电池的SOH,其中,锂电池的电压、锂电池的温度和锂电池的SOH为当前时刻下,该锂电池的电压、温度和SOH,充电电流为从该锂电池充电的起始时刻到当前时刻的充电电流。在通过上述步骤S302得到该锂电池的析锂估算模型后,根据锂电池的充电电流、锂电池的充电时间以及该锂电池的析锂估算模型中的
可以确定锂电池的SOC。根据该锂电池的SOC、温度T和SOH进行查表,可以确定OCV
neg以及OCV
cell,然后,根据电压Vcell、OCV
neg、OCV
cell、V
neg=OCV
neg-α(V
cell-OCV
cell)以及锂电池的析锂估算模型,可以确定该锂电池的负极的实时电位值V
neg。
需要说明的是,相对于根据通过拆解或改造电池获取到的锂电池的正极或负极的电位,来判断该锂电池是否发生析锂,本申请可以在不破坏电池完整性的情况下,即不改造或拆解电池的情况下,将可直接获取到锂电池的充电电流、电压、温度、SOH,输入到该锂电池的析锂估算模型中,得到锂电池的负极的实时电位,进而根据该锂电池的负极的实时电位确定该锂电池是否发生析锂。
S304、若锂电池的负极的实时电位值小于零,则确定锂电池发生析锂。
一般的,若锂电池的负极实时电位值小于零,则析锂条件被激活,锂电池发生析锂;若锂电池的负极实时电位大于零,则析锂条件被去激活,锂电池不发生析锂。因此,若利用析锂估算模型得到的锂电池的负极实时电位值小于零,则确定该锂电池发生析锂;若利用析锂估算模型得到的锂电池的负极实时电位值大于零,则确定该锂电池不发生析锂;若利用析锂估算模型得到的锂电池的负极实时电位值为零,则认为该锂电池开始析锂或者结束析锂。
在一种可能的实现方式中,通过将锂电池在充电过程中每一时刻的温度、SOH、充电电流、电压,输入该锂电池的析锂估算模型中,可以确定该锂电池在其充电过程中每一时刻的负极实时电位值,从而确定该锂电池开始析锂的时刻、结束析锂的时刻,以及析锂过程中负极实时电位值小于零的程度。随后,根据所得到的锂电池开始析锂的时刻、结束析锂的时刻、或者析锂过程中负极实时电位值小于零的程度,可以确定该锂电池的析锂严重程度。
在一种可能的实现方式中,在确定锂电池发生析锂之后,输出析锂告警信息。其中,该析锂告警信息中包括析锂发生时刻、析锂终止时刻、析锂发生时刻对应的SOC,以及析锂严重等级中至少一项。根据上述描述可知,该析锂严重等级是根据锂电池的析锂持续时长以及该锂电池的负极的实时电位值的大小来确定的。
在一种可能的实现方式中,在获取到锂电池的负极的实时电位值后,可以根据该实时电位值的大小,调节该锂电池的充电电流。比如,减小该锂电池的充电电流,以使得锂电池远离析锂状态,处于安全充电状态,进而确保该锂电池在充电过程中的安全性。
示例性的,若锂电池的负极的实时电位值较低,例如小于或等于零,或者大于零但小于预设电位阈值,则锂电池发生析锂的风险较高,可适当减小锂电池的充电电流,以使锂电池远离析锂状态,提高该锂电池充电过程的安全性;若锂电池的负极的实时电位值大于零或预设电位阈值,则可适当增大锂电池的充电电流,以提高锂电池的充电速率。
通过上述析锂估算模型以及适当的充电电流的调节,可以在保证锂电池充电安全性的同时,尽可能的提高锂电池的充电速度,提升用户的充电体验。
在一种可能的实现方式中,根据上述步骤,可以得到不同温度、不同SOH和不同SOC下的锂电池的负极实时电位,从而根据该锂电池的负极实时电位和充电速率,确定不同SOH、不同温度和不同SOC下该锂电池未发生析锂时对应的最大充电速率,进而根据该最大充电速率和该锂电池的容量,确定该锂电池所允许的最大安全充电电流。一般,可以通过离线方式或者车载环境方式进行测量,来确定锂电池所允许的最大安全充电电流。当通过离线方式进行测量时,可将确定的不同条件下的锂电池所允许的最大安全充电电流作为最大安全充电电流阈值存储在BMS中;通过车载环境方式进行测量时,BMS可直接测量得到不同条件下锂电池所允许的最大安全充电电流阈值。这样,BMS在控制充放电单元对锂电池进行充电时,可以根据不同条件下锂电池所允许的最大安全充电电流阈值调节充电电流,使充电电流恒处于安全的充电电流范围内,从而确保锂电池在充电过程中的安全性。
在上述过程中,不需要对锂电池进行改造或拆解等操作,通过将锂电池的充电电流、SOH、SOH、温度等信息输入其析锂估算模型中,即可得到锂电池的负极实时电位值,进而根据该负极实时电位值确定锂电池是否发生析锂,以简化析锂检测的过程。由于锂电池在析锂之后得到的锂分布在该锂电池的负极上,因此,相对于其他参数来说,负极的实时电位值可以更准确的表示出该锂电池是否发生了析锂,保证析锂检测的可靠性。
可选的,在一种可能的实现方式中,在上述步骤S301之前,本申请还提供一种锂电池的析锂检测方法,用于确定锂电池的SOH和温度与锂电池的析锂估算模型中的目标参数之间的对应关系。如图4所示,该方法包括如下步骤S401-S406:
S401、使用预设充电倍率、第一充电倍率、第二充电倍率、第三充电倍率对不同温度、不同SOH的锂电池充电。
关于预设充电倍率、第一充电倍率、第二充电倍率和第三充电倍率的介绍,可以参见下述表述,在此不进行赘述。关于对锂电池充电的过程的介绍可以参见图9所示的实施例,在此也不进行赘述。
可选的,使用预设充电倍率、第一充电倍率、第二充电倍率、第三充电倍率先对同一温度、同一SOH的相同锂电池进行循环充电。
S402、确定锂电池在不同的SOC对应的锂电池的开路电压OCV以及锂电池在不同的SOC下对应的锂电池的负极的OCV。
可选的,在使用预设充电倍率对锂电池充电的过程中,确定锂电池在不同的SOC对应的锂电池的开路电压OCV以及锂电池在不同的SOC下对应的锂电池的负极的OCV。
其中,锂电池的负极的OCV为该负极材料构成的电极相对于锂电极的参比电位,该锂电极即为参比电极。参比电极即测量各种电极电势时,作为参照比较的电极。该参比电极也可以根据实际应用情况选择其它的合适的材料,本申请中以参比电极为锂电极为例来进行技术方案的介绍。
可选的,将该锂电池改造为三电极电池,或者构建负极纽扣电池,即以锂电池的负极材料为负极,以锂为正极构建负极纽扣电池。以相同的预设充电倍率对锂电池、负极纽扣电池充电,并在充电过程中,对锂电池和负极纽扣电池的开路电压、充电容量进行检测,从而得到该两种电池在充电过程中,开路电压随充电容量的变化过程。根据锂电池和负极纽扣电池的充电容量分别与其电池额定电量的比值,即锂电池的SOC和负极纽 扣电池的SOC,确定这两种电池在充电过程中,开路电压随各自SOC的变化,从而确定锂电池在不同电池荷电状态SOC对应的锂电池的OCV,以及锂电池在不同SOC下对应的负极的OCV。其中,负极纽扣电池的OCV即为锂电池的负极的OCV。
可选的,在使用预设充电倍率对锂电池充电的过程中,获取锂电池的OCV与其充电容量的对应关系、以及锂电池的负极的OCV与该负极的充电容量的对应关系。基于上述对应关系,获取锂电池的dV/dQ曲线、锂电池的负极的dV/dQ曲线。随后,基于锂电池的dV/dQ曲线中的特征峰,对锂电池的负极的dV/dQ曲线进行平移或缩放处理(和/或ICA特征分析),使得锂电池的负极的dV/dQ曲线的特征峰与锂电池的dV/dQ曲线的特征峰对齐。根据特征峰对齐后的锂电池的负极的dV/dQ曲线和锂电池的dV/dQ曲线,获取到锂电池在不同的SOC对应的锂电池的OCV以及锂电池在不同的SOC下对应的负极的OCV。
相类似的,还可以以锂电池的正极为正极,以锂为负极来构建正极纽扣电池。在以预设充电倍率对正极纽扣电池充电的过程中,对正极纽扣电池的开路电压、充电容量进行检测,从而得到该正极纽扣电池在充电过程中,其开路电压随其充电容量变化的过程。根据正极纽扣电池的充电容量与其电池额定电量的比值,确定锂电池在不同SOC下对应的正极的OCV,其中,正极纽扣电池的OCV即为该锂电池的正极的OCV。随后,还可以基于锂电池的正极的OCV与该正极的充电容量的对应关系,获取锂电池的正极的dV/dQ曲线。并基于锂电池的dV/dQ曲线中的特征峰,对锂电池的正极的dV/dQ曲线进行平移或缩放处理,使得电池的正极的dV/dQ曲线的特征峰与锂电池的dV/dQ曲线的特征峰对齐。
示例性的,使用1/20C的充电倍率对锂电池、负极纽扣电池和正极纽扣电池充电,得到锂电池的OCV与其充电容量的对应关系,锂电池的负极的OCV(即负极纽扣电池的OCV)与负极纽扣电池充电容量的对应关系,以及锂电池的正极的OCV(即正极纽扣电池的OCV)与正极纽扣电池充电容量的对应关系。这三对应关系分别如图5(a)所示,图5(a)中所示横坐标为锂电池SOC、正极纽扣电池SOC、负极纽扣电池SOC(或者横坐标也可以是锂电池充电容量、正极纽扣电池充电容量、负极纽扣电池充电容量),纵坐标为锂电池OCV、锂电池正极OCV或锂电池负极OCV。根据图5(a)所示的对应关系,进行微分分析,分别得到锂电池、锂电池正极、锂电池负极的dV/dQ曲线。以锂电池的dV/dQ曲线为基准,平移或缩放锂电池正极、锂电池负极的dV/dQ曲线,使得锂电池、锂电池正极、锂电池负极的dV/dQ曲线中的特征峰对齐,彼此对齐的特征峰表示相同的物理含义。如图5(b)所示,特征峰对齐后的锂电池、锂电池正极、锂电池负极的dV/dQ曲线,分别为图中的A、B、C所示,A、B、C所在坐标的横坐标为SOC,纵坐标为锂电池、锂电池正极、锂电池负极的dV/dQ值。随后,根据图5(b),可以得到如图5(c)所示的曲线C和D,其中,C表示锂电池在不同SOC对应的锂电池的OCV,D表示锂电池负极在不同SOC下对应的负极的OCV。
在一种可能的实现方式中,锂电池的充电容量是根据锂电池从充电开始到当前时刻的充电电流进行计算得到的。
需要说明的是,预设充电倍率为较小的充电倍率,在较小的充电倍率下对锂电池充电,可以避免锂电池的极化效应。示例性的,该预设充电倍率可以为1/20C等。另外,在构建正极纽扣电池和负极纽扣电池时,可在将锂电池的电量放空并静置,使锂电池的正极活性材料和负极活性材料处于较为安全的状态后,再拆解该锂电池,随后选用与锂 电池中相同的电解液、锂电极和拆解得到的锂电池的负极活性材料和正极活性材料,构建得到所需的正极纽扣电池和负极纽扣电池。其中,整个纽扣电池的组装和锂电池的拆解过程在手套箱中进行。
S403、在使用第一充电倍率、第二充电倍率或第三充电倍率对锂电池充电的过程中,分别获取锂电池在不同SOC下对应的温度和压力。
其中,锂电池在不同SOC下对应的压力用于指示该锂电池在充电过程中的外部膨胀体积的变化。
使用不同充电倍率对锂电池进行充电的过程中,锂电池的温度和压力等相关状态参数会有不同的变化,同时锂电池在不同的充电倍率下的压力变化可能来自锂离子脱嵌效应压力、温度效应压力或者析锂效应压力中的一种或者多种。因此,在一种可能的实现方式中,对于第一充电倍率、第二充电倍率、第三充电倍率中的每个充电倍率,在使用该充电倍率对锂电池进行充电的过程中,检测锂电池的的压力和温度等,从而这三个充电倍率对应得到三组温度和压力。即锂电池在不同SOC下对应的温度和压力包括第一温度和第一压力、第二温度和第二压力,以及(第三温度和)第三压力。其中,在第一充电倍率下,锂电池在不同SOC下对应的温度和压力为第一温度和第一压力,第一压力为发生锂离子脱嵌效应、温度效应和析锂效应所导致的总压力;在第二充电倍率下,锂电池在不同SOC下对应的温度和压力为第二温度和第二压力,第二压力为发生锂离子脱嵌效应、温度效应所导致的总压力;在第三充电倍率下,锂电池在不同SOC下对应的温度和压力分别为第三温度和第三压力,第三压力为发生锂离子脱嵌效应所导致的压力。
在一种可能的实现方式中,可分别使用三组充电倍率对锂电池循环充电,每组充电倍率中可以包括至少一个充电倍率,这至少一个充电倍率均属于同一充电倍率,即第一充电倍率、或第二充电倍率、或第三充电倍率。可选的,这三组充电倍率中包括第一组充电倍率、第二组充电倍率和第三组充电倍率,第一组充电倍率中的充电倍率属于第一充电倍率,第二组充电倍率中的充电倍率属于第二充电倍率,第三组充电倍率中的充电倍率属于第三充电倍率。
也就是说,第一充电倍率为锂电池发生锂电子脱嵌效应、温度效应和析锂效应的充电倍率,第二充电倍率为锂电池只发生锂电子脱嵌效应和温度效应的充电倍率,第三充电倍率为锂电池只发生锂电子脱嵌效应的充电倍率。一般的,在其他条件相同的情况下,充电倍率越大,则锂电池发生析锂的可能性较大。若第一充电倍率、第二充电倍率与第三充电倍率分别对应不同的充电速度,则第一充电倍率大于第二充电倍率,第二充电倍率大于第三充电倍率。其中,每种效应及其该效应所导致的压力的具体理解,可以参见上述内容。
示例性的,第一充电倍率的取值范围[a1,b1],第二充电倍率的取值范围为[a2,b2],第三充电倍率的取值范围为[a3,b3],[a1,b1]大于[a2,b2],[a2,b2]大于[a3,b3]。例如,[a1,b1]等于[3C,5C],[a2,b2]等于[0.5C,2C],[a3,b3]等于[0.05C,0.2C]。另外,对于不同规格或不同状态的锂电池,上述充电倍率的取值范围可以不同。
在实际应用中,当分别使用不同的三组充电倍率对锂电池充电时,每组充电倍率可对应检测得到多组压力和温度。比如,选择每组充电倍率中最小的充电倍率对应的压力和温度作为该组充电倍率对应的压力和温度,或者对每组充电倍率对应检测得到的多组压力和温度进行平均值计算以得到一组压力和温度,或者通过某种数学组合的方式从每组充电倍率对应检测得到的多组压力和温度中确定一组压力和温度等,本申请实施例对 此不作具体限制。
下面对锂电池在不同的充电倍率下的压力变化进行介绍说明。具体的,当使用第三充电倍率对锂电池进行充电时,锂电池的温度变化不大,且无析锂现象发生,此时可认为锂电池在充电过程中发生了锂离子脱嵌效应,但未发生温度效应和析锂效应,也就是说,锂电池的压力变化是由锂离子脱嵌效应所引起的,即锂电池的压力为锂离子脱嵌效应压力,该锂离子脱嵌效应压力可以为关于锂电池的SOC的函数。当使用第二充电倍率对锂电池进行充电时,锂电池的温度变化显著,但无析锂现象发生,此时可认为锂电池在充电过程中发生了锂离子脱嵌效应和温度效应,但未发生析锂效应,从而锂电池的压力变化是由锂离子脱嵌效应和温度效应所引起的,即锂电池的压力为锂离子脱嵌效应压力和温度效应压力之和,该温度效应压力可以为关于锂电池的温度的函数。当使用第一充电倍率对锂电池进行充电时,锂电池的温度变化显著,同时可能有析锂现象发生,此时可认为锂电池在充电过程中发生了锂离子脱嵌效应、温度效应和析锂效应,从而锂电池的压力变化是由锂离子脱嵌效应、温度效应和析锂效应所引起的,即锂电池的压力为锂离子脱嵌效应压力、温度效应压力和析锂效应压力之和。
锂电池在不同的充电倍率下,锂电池的压力与锂离子脱嵌效应压力、温度效应压力和析锂效应压力之间的对应关系如下表2所示。在表2中,充电倍率包括第一充电倍率、第二充电倍率和第三充电倍率等,第一充电倍率时锂电池的压力(即第一压力)等于锂离子脱嵌效应所导致的压力、温度效应所导致的压力和析锂效应所导致的压力之和,第二充电倍率时锂电池的压力(即第二压力)等于锂离子脱嵌效应所导致的压力和温度效应所导致的压力之和,第三充电倍率时锂电池的压力(即第三压力)等于锂离子脱嵌效应所导致的压力。
表2
需要说明的是,对于不同规格或不同形式的锂电池对应的第一充电倍率、第二充电倍率和第三充电倍率可能相同,也可能不同,本申请实施例对此不作具体限定。上述第一充电倍率、第二充电倍率和第三充电倍率可以事先由本领域技术人员根据所检测的锂电池的规格或形式进行设置,比如,第三充电倍率可以包括0.05C、0.1C和0.2C等,第二充电倍率可以包括0.5C、1C和2C等,第一充电倍率可以包括3C、4C和5C等。
在一种可能的实现方式中,获取锂电池的温度和压力的同时,还需要获取锂电池的充电电流。其中,锂电池的温度可以通过温度传感器测量得到,锂电池的压力可以通过压力传感器测量得到,锂电池的充电电流可以通过电流传感器测量得到。对测量得到的锂电池的充电电流进行积分处理,则可以确定该锂电池在各个不同温度、压力时所对应的SOC,从而得到锂电池在不同SOC下对应的温度和压力。
在一种可能的实现方式中,使用第一充电倍率对锂电池循环充电,将在第一充电倍率对应的充电过程中检测到的数据(例如上述温度和压力)的均值,作为使用该第一充电倍率对锂电池充电时,锂电池在不同SOC下对应的数据。同理,将在第二充电倍率对 应的充电过程中检测到的数据的均值,作为使用该第二充电倍率对锂电池充电时,锂电池在不同SOC下对应的数据。将在第三充电倍率对应的充电过程中检测到的数据的均值,作为使用该第三充电倍率对锂电池充电时,锂电池在不同SOC下对应的数据。通过上述过程,避免充电过程中的偶然数据的出现,提高检测到的锂电池的数据的可靠性。
S404、根据锂电池在不同SOC下对应的温度和压力,确定该锂电池在不同SOC下的析锂效应压力。
其中,锂电池的析锂效应压力用于指示锂电池由析锂效应导致的压力变化,关于析锂效应压力的具体介绍可以参见上述内容。
可选的,根据不同温度下第二压力与第三压力的差值、以及第二温度,确定锂电池的温度效应压力和温度之间的关联关系,该温度效应压力用于指示锂电池在不同温度下由温度效应导致的压力变化。其中,温度效应压力用于指示锂电池在不同温度下由温度效应导致的压力变化。随后,根据第一温度以及温度效应压力和温度之间的关联关系,确定在使用第一充电倍率对锂电池充电的过程中,锂电池在不同SOC下对应的锂电池的温度效应压力。最后,将锂电池的温度效应压力和第三压力之和与第一压力的差值,确定为其在不同SOC下对应的析锂效应压力。
在一种可能的实现方式中,使用第一充电倍率对锂电池充电的过程中,不同SOC下对应的第一温度和第一压力可表示为{(T
11,F
11)、(T
12,F
12)、……、(T
1n,F
1n)}。相类似的,使用第二充电倍率对锂电池充电的过程中,不同SOC下对应的第二温度和第二压力可表示为{(T
21,F
21)、(T
22,F
22)、……、(T
2n,F
2n)}。使用第三充电倍率对锂电池充电的过程中,不同SOC下对应的第三温度和第三压力可表示为{(,T
31,F
31)、(T
32,F
32)、……、(T
3n,F
3n)}。其中,T为锂电池的温度,F为压力。
在一种可能的实现方式中,由于对锂电池的充电电流进行积分,可得到锂电池的充电容量,进而得到锂电池SOC。因此,在一定程度上,在不同SOC下对应的第一温度和第一压力可表示为{(I
11,T
11,F
11)、(I
12,T
12,F
12)、……、(I
1n,T
1n,F
1n)}。其中,I为锂电池的充电电流,可以用于表示与第一温度和第一压力对应的锂电池的SOC。V为锂电池在不同SOC时的电压。相类似的,使用第二充电倍率对锂电池充电的过程中,不同SOC下对应的第二温度和第二压力可表示为{(I
21,T
21,F
21)、(I
22,T
22,F
22)、……、(I
2n,T
2n,F
2n)}。使用第三充电倍率对锂电池充电的过程中,不同SOC下对应的第三温度和第三压力{(I
31,T
31,F
31)、(I
32,T
32,F
32)、……、(I
3n,T
3n,F
3n)}。
在一种可能的实现方式中,对锂电池充电的过程中,通过压力传感器、电流传感器、温度传感器、电压传感器等,获取锂电池在不同SOC下的充电电流、压力、电压和温度等信息。此时,针对不同SOC,第一充电倍率下,锂电池的相关信息可以表示为{(I
11,V
11,T
11,F
11)、(I
12,V
12,T
12,F
12)、……、(I
1n,V
1n,T
1n,F
1n)}。相类似的,针对不同SOC,第二充电倍率下,锂电池的相关信息可以表示为{(I
21,V
21,T
21,F
21)、(I
22,V
22,T
22,F
22)、……、(I
2n,V
2n,T
2n,F
2n)}。针对不同SOC,第二充电倍率下,锂电池的相关信息可以表示为{(I
31,V
31,T
31,F
31)、(I
32,V
32,T
32,F
32)、……、(I
3n,V
3n,T
3n,F
3n)}。其中,I为锂电池的充电电流,V为锂电池的充电电压,T为锂电池的温度,F为锂电池的压力。
示例性的,若第二充电倍率下,锂电池的相关信息表示为D2={(I
21,V
21,T
21,F
21)、(I
22,V
22,T
22,F
22)、……、(I
2n,V
2n,T
2n,F
2n)},第三充电倍率下,锂电池的相关信息表示为D3={(I
31,V
31,T
31,F
31)、(I
32,V
32,T
32,F
32)、……、(I
3n,V
3n, T
3n,F
3n)}。其中,T
21=T
31且T
31=T
32=……=T
3n。对D2和D3进行数据处理,可得到D21={(SOC
21,ΔT
21,F
21)、(SOC
22,ΔT
22,F
22)、……、(SOC
2n,ΔT
2n,F
2n)}、D31={(SOC
31,F
31)、(SOC
32,F
32)、……、(SOC
3n,F
3n)}。其中,SOC
21=SOC
31,SOC
22=SOC
32,……,SOC
2n=SOC
3n。F
3i为第三充电倍率下的不同SOC对应的锂离子脱嵌效应压力,F
2i为第二充电倍率下的不同SOC对应的锂离子脱嵌效应压力和温度效应压力之和。根据D31中SOC
3i与压力值F
3i之间的对应关系,可以确定D21中锂离子脱嵌效应压力,这里表示为D22={(SOC
21,ΔT
21,F’
21)、(SOC
22,ΔT
22,F’
22)、……、(SOC
2n,ΔT
2n,F’
2n)},F’
2i=F
3i,则根据D21和D22可以确定第二充电倍率下的温度效应压力D23={(SOC
21,ΔT
21,F
21-F’
21)、(SOC
22,ΔT
22,F
22-F’
22)、……、(SOC
2n,ΔT
2n,F
2n-F’
2n)}。其中,ΔT
2i=T
2i-T
21,i的取值范围为1~n(n为正整数)。从而可以得到温度效应压力与温度的对应关系。
进一步的,第一充电倍率下,锂电池的相关信息表示为D1=(I
11,V
11,T
11,F
11)、(I
12,V
12,T
12,F
12)、……、(I
1n,V
1n,T
1n,F
1n)},对D1进行数据处理,可得到D11={(SOC
11,ΔT
11,F
11)、(SOC
12,ΔT
12,F
12)、……、(SOC
1n,ΔT
1n,F
1n)}。其中,ΔT
1i=T
1i-T
11。根据上述第三充电倍率下的锂离子脱嵌效应压力D31中SOC
3i与压力值F
3i之间的对应关系,可以确定D11中的锂离子脱嵌效应压力,这里表示为D12={(SOC
11,ΔT
11,F’
11)、(SOC
12,ΔT
12,F’
12)、……、(SOC
1n,ΔT
1n,F’
1n)}。根据上述第二充电倍率下的温度效应压力D23中ΔT
2i与压力值F
2i之间的对应关系,可以确定D11中的温度效应压力,这里表示为D13={(SOC
11,ΔT
11,F”
11)、(SOC
12,ΔT
12,F”
12)、……、(SOC
1n,ΔT
1n,F”
1n)}。F
1i为第一充电倍率下的锂离子脱嵌效应压力F’
1i、温度效应压力F”
1i和析锂效应压力之和,则根据D11、D12和D13可以得到析锂效应压力,这里表示为D14={(SOC
11,ΔT
11,F
11-F’
11-F”
11)、(SOC
12,ΔT
12,F
12-F’
12-F”
12)、……、(SOC
1n,ΔT
1n,F
1n-F’
1n-F”
1n)}。其中,ΔT
3i=T
3i-T
31,i的取值范围为1~n。
在一种可能的实现方式中,使用一定放电倍率对锂电池放电,同时在放电过程中也可以检测锂电池的电流、压力、电压和温度等信息,以按照上述类似的方式确定锂电池在不同SOC下的析锂效应压力。
S405、确定锂电池的负极的极化电压以及锂电池的极化电压。
可选的,根据锂电池在不同SOC对应的锂电池的OCV、锂电池在不同的SOC下对应的负极的OCV和锂电池在不同SOC下对应的析锂效应压力,确定锂电池的负极的极化电压以及锂电池的极化电压。
当确定析锂效应压力后,可以根据析锂效应压力中压力值的变化对锂电池的析锂进行检测。具体的,析锂效应压力中包括多个不同SOC的压力值,且由于析锂效应压力是由于析锂效应所造成的,可根据不同SOC的析锂效应压力值的变化情况,确定锂电池发生析锂的起始SOC和锂电池结束析锂的终止SOC。当析锂效应压力中的压力值为零、或者接近于零时,可确定锂电池未发生析锂;当析锂效应压力中的压力值由零上升为非零、且仍处于上升趋势时,可确定锂电池发生了析锂,也就是说,可将析锂效应压力中压力值从零转换为非零时对应的SOC确定为锂电池发生析锂的起始SOC;当析锂效应所导致的压力中的压力值上升为最大值后开始逐渐减小时,可确定锂电池的析锂结束,也就是说,可将析锂效应压力中最大压力值对应的SOC确定为锂电池析锂结束时的终止SOC。
另外,在锂电池的析锂开始时刻,其负极电压值为零,也就是说,该起始SOC对应 的负极OCV与负极的极化电压的差值为零。因此,可以将该起始SOC对应的锂电池的负极OCV,确定为该负极的极化电压。且在锂电池的析锂结束时刻,锂电池的极化电压为其该终止SOC对应的锂电池的电压与该终止SOC对应的锂电池的OCV的差值。
示例性的,以图6所示的析锂效应压力中不同SOC与压力值之间的对应关系为例,当SOC处于0~0.55的范围内时压力值等于0、或接近于零,当SOC处于0.55~0.87的范围内时压力值由零上升为非零且处于上升趋势,并在SOC=0.87时取得最大压力值,当SOC处于0.87~1的范围内时压力值处于下降趋势。图6中A点表示析锂效应压力中压力值由零转换为非零且仍处于上升趋势时的转换点,B点表示析锂效应压力中最大压力值对应的峰值点。其中,A点(0.55,0)可以称为析锂的起始点,SOC=0.55即为锂电池析锂起始时的荷电状态(即发生析锂的起始SOC);B点(0.87,230)可以称为析锂的终止点,SOC=0.87即为锂电池析锂的结束时的荷电状态(即发生析锂的终止SOC)。
或者,在另一种可能的实现方式中,当该析锂效应压力值中存在连续多个压力值大于零时,可确定该锂电池发生了析锂,再将析锂效应压力中压力值从零转换为非零时对应的SOC确定为锂电池发生析锂的起始SOC。
S406、建立锂电池的温度、锂电池的SOH与目标参数的对应关系。
可选的,使用预设充电倍率、第一充电倍率、第二充电倍率、第三充电倍率先对同一温度、同一SOH的相同锂电池进行循环充电后,执行上述步骤S402和S405。在经步骤S405确定该锂电池在该温度和SOH下对应的锂电池的负极的极化电压和锂电池的极化电压后,即可建立锂电池在该温度和SOH与目标参数的对应关系,该目标参数即为通过步骤S405得到的锂电池的负极的极化电压和锂电池的极化电压的比值。随后,通过类似过程,可建立该锂电池的其他温度、SOH与目标参数的对应关系,也可建立其他锂电池在不同温度、SOH下与目标参数的对应关系。其中,该对应关系可以以表格的形式存储,如上述表1所示。
示例性的,若经过上述步骤得到锂电池的负极极化电压为86.1mV,锂电池的极化电压为212.7V,则可以得到该锂电池的负极的极化电压与锂电池的极化电压的比值α为0.4048。
需要说明的是,该锂电池的负极的极化电压和锂电池的极化电压的比值,即目标参数,可视为不随SOC或充电倍率等发生变化,但是随锂电池的SOH和温度而变化,即该比值与锂电池的SOH和温度存在对应关系。
示例性的,在确定锂电池在一定温度和SOH的析锂估算模型后,分别使用1C和1.5C的充电倍率对该锂电池充电,获取锂电池在充电过程中的充电电流、电压,将该充电电流、电压、温度和SOH输入上述确定的锂电池的析锂估算模型,得到锂电池在不同SOC下的负极的实时电位如图7(a)和图7(b)所示。如图7(a)和图7(b)所示,在使用1C的充电倍率对锂电池充电的过程中,锂电池的负极的实时电位恒大于零,可确定锂电池未发生析锂;在使用1.5C的充电倍率对锂电池充电的过程中,在锂电池的SOC为0.62-0.89时,该锂电池的负极实时电位小于零,也就是说,该锂电池在其SOC为0.62-0.89时发生了析锂。以1C和1.5C充电倍率对不同SOH的该锂电池循环充电,得到锂电池在不同SOH下可以循环充电的次数,如图7(c)所示,在锂电池的SOH为80.00%时,使用1.5C对锂电池充电的过程可以循环180次,使用1C对锂电池充电的过程可以循环1500次,180远小于1500。因此,图7(c)可以间接反映出在使用1.5C对锂电池充电的过程中,该锂电池很可能发生了析锂。综上,通过图7(a)、图7(b)和图7(c)可以确定 本申请可以较为准确地确定锂电池在充电过程中是否发生了析锂。
可选的,为了保证锂电池的压力值的测量准确性和稳定性,可对锂电池和压力传感器进行固定。示例性的,如图8所示,当锂电池为电芯或者电池模组时,可通过铝板固定该电芯和压力传感器,或者铝板固定电池模组和压力传感器,并通过螺栓固定铝板,以保证压力值的测量准确性和稳定性。
在上述步骤S401-步骤S403中,为了获取较为可靠的信息,通常会使用相同的充电倍率对锂电池进行多次充电和放电,如图9所示,该多次充电和放电的过程包括步骤S901-S907:
S901、放空操作,先将锂电池进行放空操作(也可以称为放电操作),比如采用恒流恒压的放电方式或其他放电方式,放电操作的目的使锂电池的SOC接近于0%,比如使锂电池的SOC处于0~5%。
S902、静置操作,静置操作的目的为使锂电池处于电-热-化学-压力准平衡状态,比如,静置操作的时间可以为0~10h。
S903、选择充电倍率,比如,选择预设充电倍率、第一充电倍率、第二充电倍率或第三充电倍率。
S904、使用选择的充电倍率对锂电池完成满充电操作,即使用选择的充电倍率对锂电池充电,以使锂电池处于满充电状态。
可选的,在充电过程中,可记录锂电池的电流值I、电压值V、温度值T和压力值F。
具体的,使用选择的充电倍率完成满充电操作,可以包括:根据该充电倍率设置充放电单元的充电电流,并控制充放电单元使用设置的充电电流对锂电池进行充电,当锂电池的SOC=1时即完成满充电操作。
S905、静置操作,该静置操作的目的与上述步骤S802相同。
S906、将锂电池进行放空操作。
可选的,在放电过程中,可记录锂电池的电流值I、电压值V、温度值T和压力值F。
S907、静置操作;之后,返回步骤S903重新选择充电倍率后向下继续执行。
需要说明的是,将锂电池进行放空操作时可以采用一定的放电倍率进行放电操作,放电倍率的大小可以由本领域技术人员根据实际情况进行设置,本申请实施例对此不作具体限制。另外,上述静置操作的时间也可以由本领域技术人员根据实际情况进行设置,本申请实施例对此同样不作具体限制。
上述主要从应用锂电池的设备的角度对本申请实施例提供的方案进行了介绍。可以理解的是,应用锂电池的设备为了实现上述功能,其包含了执行各个功能相应的硬件结构和/或软件模块。本领域技术人员应该很容易意识到,结合本文中所公开的实施例描述的各示例的单元及算法步骤,本申请能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行,取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能,但是这种实现不应认为超出本申请的范围。
本申请实施例可以根据上述方法示例对锂电池的析锂检测装置进行功能模块的划分,例如,可以对应各个功能划分各个功能模块,也可以将两个或两个以上的功能集成在一个模块中。上述集成的模块既可以采用硬件的形式实现,也可以采用软件功能模块的形式实现。需要说明的是,本申请实施例中对模块的划分是示意性的,仅仅为一种逻辑功能划分,实际实现时可以有另外的划分方式。下面以采用对应各个功能划分各个功 能模块为例进行说明:
图10为本申请实施例提供的一种锂电池的析锂检测装置的结构示意图,如图10所示,该装置包括:目标参数确定单元1001、模型确定单元1002、诊断参数获取单元1003、析锂诊断单元1004、电流控制单元1005、析锂告警单元1006。该析锂检测装置可以为BMS,或者集成有BMS的芯片,目标参数确定单元1001、诊断参数获取单元1003、析锂诊断单元1004在具体实现时均可以为图2所示的BMS中的析锂安全诊断模块204。电流控制单元1005在具体实现时可以为图2所示的BMS中的防析锂管理模块203。析锂告警单元1006在具体实现时可以为图2所示的BMS中的通信模块207。
目标参数确定单元1001,用于根据锂电池的电池健康状态SOH、该锂电池的温度,以及锂电池的SOH和锂电池的温度与目标参数的对应关系,确定该锂电池对应的目标参数。该锂电池对应的目标参数为该锂电池的负极的极化电压与该锂电池的极化电压的比值,极化电压为实际电压与开路电压的差值。
可选的,在确定锂电池对应的目标参数之前,该目标参数确定单元1001,还用于使用预设充电倍率、第一充电倍率、第二充电倍率、第三充电倍率对不同温度、不同SOH的锂电池充电。在使用预设充电倍率对锂电池充电的过程中,确定锂电池在不同电池荷电状态SOC对应的锂电池的是开路电压OCV以及锂电池在不同的SOC下对应的锂电池的负极的OCV,该锂电池的负极的OCV为该锂电池的负极相对于锂电极的参比电位。在使用第一充电倍率、第二充电倍率或第三充电倍率对锂电池充电的过程中,分别获取锂电池在不同SOC下对应的温度和压力,该锂电池在不同SOC下对应的压力用于指示该锂电池在充电过程中的外部膨胀体积的变化。随后,根据锂电池在不同SOC下对应的温度和压力,确定锂电池在不同SOC下对应的析锂效应压力,该锂电池在不同SOC下对应的析锂效应压力用于指示该锂电池由析锂效应导致的压力变化。根据锂电池在不同SOC对应的锂电池的OCV、锂电池在不同的SOC下对应的该锂电池的负极的OCV和锂电池在不同SOC下对应的析锂效应压力,确定锂电池的负极的极化电压以及锂电池的极化电压。最后,建立锂电池的温度、锂电池的SOH和目标参数,即锂电池的负极的极化电压与锂电池的极化电压的比值,的对应关系。
在这一种可能的实现方式中,锂电池在不同SOC下对应的温度和压力包括与第一充电倍率对应的第一温度和第一压力,与第二充电倍率对应的第二温度和第二压力,以及与第三充电倍率对应的第三压力。其中,第一压力为发生锂离子脱嵌效应、温度效应和析锂效应所导致的总压力,第二压力为发生锂离子脱嵌效应、温度效应所导致的总压力,第三压力为发生锂离子脱嵌效应所导致的压力。
在一种可能的实现方式中,目标参数确定单元1001,具体用于:根据不同SOC下第二压力和第三压力的差值、以及第二温度,确定锂电池的温度效应压力与温度之间的关联关系。该锂电池的温度效应压力用于指示该锂电池在不同温度下由温度效应导致的压力变化。根据第一温度和上述关联关系,确定在使用第一充电倍率对锂电池充电的过程中,该锂电池在不同SOC下对应的温度效应压力。最后,将该锂电池在不同SOC下对应的温度效应压力和第三压力之和与第一压力的差值,确定为该锂电池在不同SOC下对应的析锂效应压力。
在一种可能的实现方式中,目标参数确定单元1001,具体用于:将起始SOC对应的锂电池的负极的OCV,确定为锂电池的负极的极化电压,其中,起始SOC即析锂效应压力的压力值从零转折为非零时对应的SOC。将终止SOC对应的锂电池的OCV与锂电 池的(实际)电压的差值,确定为锂电池的极化电压,其中,该终止SOC即为析锂效应压力的最大压力值对应的SOC。
在一种可能的实现方式中,预设析锂估算模型为
其中,I为锂电池的充电电流,Q为锂电池的额定电量,∫
Idt表示锂电池在当前时刻的电容量,SOC为锂电池的电池荷电状态,V
neg为锂电池的负极实时电位值,OCV
neg为锂电池的负极的开路电压,V
p,neg为锂电池的负极的极化电压,T为锂电池的温度,SOH为锂电池的电池健康状态,OCV
neg(SOC,T,SOH)为OCV
neg关于SOC、T、SOH的函数,α为锂电池的析锂估算模型中的目标参数,V
cell为锂电池的电压,OCV
cell(SOC,T,SOH)为OCV
cell关于SOC、T、SOH的函数,V
cell-OCV
cell(SOC,T,SOH)表示锂电池的极化电压。
模型确定单元1002,用于将锂电池对应的目标参数代入预设析锂估算模型中,得到该锂电池的析锂估算模型。
诊断参数获取单元1003,用于将锂电池的充电电流、锂电池的电压、该锂电池的温度和该锂电池的SOH输入该锂电池的析锂估算模型中,得到该锂电池的负极的实时电位值。
析锂诊断单元1004,用于若该锂电池的负极的实时电位值小于零,则确定该锂电池发生析锂。
可选的,在进行析锂诊断后,析锂告警单元1006用于输出析锂告警信息,该析锂告警信息包括析锂发生时刻、析锂终止时刻、所述析锂发生时刻对应的SOC、以及析锂严重等级中至少一项,该析锂严重等级是根据析锂持续时长以及所述负极的实时电位值确定的。
可选的,电流控制单元1005,用于根据负极的实时电位值,调节锂电池的充电电流。
可选的,电流控制单元1005,还用于根据析锂发生时刻以及析锂发生时刻对应的SOC,确定锂电池的最大安全充电电流。
基于此,本申请实施例还提供一种应用锂电池的设备,该设备包括锂电池、充放电设备、以及图10所示的析锂检测装置。在该设备中,该析锂检测装置用于执行上文所提供的方法示例中的相关步骤,比如,该析锂检测装置用于执行上文方法示例中的S301-S304,或者上文方法示例中的S401-S406或S901-S907等。
本领域普通技术人员可以意识到,结合本文中所公开的实施例描述的各示例的单元及算法步骤,能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行,取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能,但是这种实现不应认为超出本申请实施例的范围。
所属领域的技术人员可以清楚地了解到,为描述的方便和简洁,上述描述的系统、装置和单元的具体工作过程,可以参考前述方法实施例中的对应过程,在此不再赘述。
在本申请实施例所提供的几个实施例中,应该理解到,所揭露的系统、装置和方法,可以通过其它的方式实现。例如,以上所描述的装置实施例仅仅是示意性的,例如,单元的划分,仅仅为一种逻辑功能划分,实际实现时可以有另外的划分方式,例如多个单元或组件可以结合或者可以集成到另一个系统,或一些特征可以忽略,或不执行。另一点,所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口,装置或单元的间接耦合或通信连接,可以是电性,机械或其它的形式。
作为分离部件说明的单元可以是或者也可以不是物理上分开的,作为单元显示的部件可以是或者也可以不是物理单元,即可以位于一个地方,或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外,在本申请实施例各个实施例中的各功能单元可以集成在一个处理单元中,也可以是各个单元单独物理存在,也可以两个或两个以上单元集成在一个单元中。
功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时,可以存储在一个计算机可读取存储介质中。基于这样的理解,本申请实施例的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来,该计算机软件产品存储在一个存储介质中,包括若干指令用以使得一台计算机设备(可以是个人计算机,服务器,或者网络设备等)执行本申请各个实施例方法的全部或部分步骤。而前述的存储介质包括:U盘、移动硬盘、只读存储器(ROM,Read-Only Memory)、随机存取存储器(RAM,Random Access Memory)、磁碟或者光盘等各种可以存储程序代码的介质。
最后应说明的是:以上所述,仅为本申请的具体实施方式,但本申请的保护范围并不局限于此,任何在本申请揭露的技术范围内的变化或替换,都应涵盖在本申请的保护范围之内。因此,本申请的保护范围应以所述权利要求的保护范围为准。
Claims (19)
- 一种锂电池的析锂检测方法,其特征在于,包括:根据所述锂电池的电池健康状态SOH、所述锂电池的温度,以及所述锂电池的SOH和所述锂电池的温度与目标参数的对应关系,确定所述锂电池对应的目标参数,所述锂电池对应的目标参数为所述锂电池的负极的极化电压与所述锂电池的极化电压的比值;所述极化电压为实际电压与开路电压的差值;将所述锂电池对应的目标参数代入预设析锂估算模型中,得到所述锂电池的析锂估算模型;将所述锂电池的充电电流、所述锂电池的电压、所述锂电池的温度和所述锂电池的SOH输入所述锂电池的析锂估算模型,得到所述锂电池的负极的实时电位值;若所述锂电池的负极的实时电位值小于零,则确定所述锂电池发生析锂。
- 根据权利要求1所述的锂电池的析锂检测方法,其特征在于,在所述根据所述锂电池的电池健康状态SOH、所述锂电池的温度,以及所述锂电池的SOH和所述锂电池的温度与目标参数的对应关系,确定所述锂电池对应的目标参数之前,所述方法包括:使用预设充电倍率、第一充电倍率、第二充电倍率、第三充电倍率对不同温度、不同SOH的锂电池充电;在使用预设充电倍率对所述锂电池充电的过程中,确定锂电池在不同的电池荷电状态SOC对应的锂电池的开路电压OCV以及锂电池在不同的SOC下对应的锂电池的负极的OCV;所述锂电池的负极的OCV为所述锂电池的负极相对于锂电极的参比电位;在使用第一充电倍率、第二充电倍率或第三充电倍率对所述锂电池充电的过程中,分别获取所述锂电池在不同SOC下对应的温度和压力;所述锂电池在不同SOC下对应的压力用于指示所述锂电池在充电过程中的外部膨胀体积的变化;根据所述锂电池在不同SOC下对应的温度和压力,确定所述锂电池在不同SOC下对应的析锂效应压力;所述锂电池在不同SOC下对应的析锂效应压力用于指示所述锂电池由析锂效应所导致的压力变化;根据所述锂电池在不同SOC对应的锂电池的OCV、锂电池在不同的SOC下对应的锂电池的负极的OCV和所述锂电池在不同SOC下对应的析锂效应压力,确定所述锂电池的负极的极化电压以及所述锂电池的极化电压;建立所述锂电池的温度、所述锂电池的SOH与所述目标参数的对应关系。
- 根据权利要求2所述的锂电池的析锂检测方法,其特征在于,所述锂电池在不同SOC下对应的温度和压力包括与所述第一充电倍率对应的第一温度和第一压力、与所述第二充电倍率对应的第二温度和第二压力、以及与所述第三充电倍率对应的第三压力;其中,所述第一压力为发生锂离子脱嵌效应、温度效应和析锂效应所导致的总压力,所述第二压力为发生所述锂离子脱嵌效应和所述温度效应所导致的总压力,所述第三压力为发生所述锂离子脱嵌效应所导致的压力。
- 根据权利要求3所述的锂电池的析锂检测方法,其特征在于,所述根据所述锂电池在不同SOC下对应的温度和压力,确定所述锂电池在不同SOC下的析锂效应压力,包括:根据不同SOC下所述第二压力与所述第三压力的差值、以及第二温度,确定所述锂电池的温度效应压力与温度之间的关联关系;所述锂电池的温度效应压力用于指示所述锂电池在不同温度下由温度效应导致的压力变化;根据所述第一温度以及所述关联关系,确定在使用所述第一充电倍率对所述锂电池充电的过程中,所述锂电池在不同SOC下对应的温度效应压力;将所述锂电池在不同SOC下对应的温度效应压力和第三压力之和与第一压力的差值,确定为所述锂电池在不同SOC下对应的析锂效应压力。
- 根据权利要求2-4任一项所述的锂电池的析锂检测方法,其特征在于,所述根据所述锂电池在不同SOC对应的锂电池的OCV、锂电池在不同的SOC下对应的锂电池的负极的OCV和所述锂电池在不同SOC下对应的析锂效应压力,确定所述锂电池的负极的极化电压以及所述锂电池的极化电压,包括:将起始SOC对应的锂电池的负极的OCV,确定为所述负极的极化电压;所述起始SOC为所述析锂效应压力的压力值从零转折为非零时对应的SOC;将终止SOC对应的锂电池的OCV与所述锂电池的电压的差值,确定为所述锂电池的极化电压;所述终止SOC为所述析锂效应压力的最大压力值对应的SOC。
- 其中,I为所述锂电池的充电电流,Q为所述锂电池的额定电量,∫ Idt表示所述锂电池在当前时刻的电容量,SOC为所述锂电池的电池荷电状态,V neg为所述锂电池的负极实时电位值,OCV neg为所述锂电池的负极的开路电压,V p,neg为所述锂电池的负极的极化电压,T为所述锂电池的温度,SOH为所述锂电池的电池健康状态,OCV neg(SOC,T,SOH)为OCV neg关于SOC、T、SOH的函数,α为所述锂电池的析锂估算模型中的目标参数,V cell为所述锂电池的电压,OCV cell(SOC,T,SOH)为OCV cell关于SOC、T、SOH的函数,V cell-OCV cell(SOC,T,SOH)表示所述锂电池的极化电压。
- 根据权利要求1-6任一项所述的锂电池的析锂检测方法,其特征在于,在所述若所述锂电池的负极的实时电位值小于零,则确定所述锂电池发生析锂之后,所述方法还包括:输出析锂告警信息,所述析锂告警信息包括析锂发生时刻、析锂终止时刻、所述析锂发生时刻对应的SOC、以及析锂严重等级中至少一项;所述析锂严重等级是根据析锂持续时长以及所述锂电池的负极的实时电位值确定的。
- 根据权利要求1-7任一项所述的锂电池的析锂检测方法,其特征在于,所述方法还包括:根据所述锂电池的负极的实时电位值,调节所述锂电池的充电电流。
- 根据权利要求7或8所述的锂电池的析锂检测方法,其特征在于,所述方法还包括:根据所述析锂发生时刻以及所述析锂发生时刻对应的SOC,确定所述锂电池的最大安全充电电流。
- 一种锂电池的析锂检测装置,其特征在于,包括:目标参数确定单元,用于根据所述锂电池的电池健康状态SOH、所述锂电池的温度,以及所述锂电池的SOH和所述锂电池的温度与目标参数的对应关系,确定所述锂电池对应的目标参数,所述锂电池的目标参数为所述锂电池的负极的极化电压与所述锂电池的极化电压的比值;所述极化电压为实际电压与开路电压的差值;模型确定单元,用于将所述锂电池对应的目标参数代入预设析锂估算模型中,得到 所述锂电池的析锂估算模型;诊断参数获取单元,用于将所述锂电池的充电电流、所述锂电池的电压、所述锂电池的温度和所述锂电池的SOH输入所述锂电池的析锂估算模型,得到所述锂电池的负极的实时电位值;析锂诊断单元,用于若所述锂电池的负极的实时电位值小于零,则确定所述锂电池发生析锂。
- 根据权利要求10所述的装置,其特征在于,所述目标参数确定单元,还用于:使用预设充电倍率、第一充电倍率、第二充电倍率、第三充电倍率对不同温度、不同SOH的锂电池充电;在使用预设充电倍率对所述锂电池充电的过程中,确定锂电池在不同的电池荷电状态SOC对应的锂电池的开路电压OCV以及锂电池在不同的SOC下对应的锂电池的负极的OCV;所述锂电池的负极的OCV为所述锂电池的负极相对于锂电极的参比电位;在使用第一充电倍率、第二充电倍率或第三充电倍率对所述锂电池充电的过程中,分别获取所述锂电池在不同SOC下对应的温度和压力;所述锂电池在不同SOC下对应的压力用于指示所述锂电池在充电过程中的外部膨胀体积的变化;根据所述锂电池在不同SOC下对应的温度和压力,确定所述锂电池在不同SOC下对应的析锂效应压力;所述锂电池在不同SOC下对应的析锂效应压力用于指示所述锂电池由析锂效应导致的压力变化;根据所述锂电池在不同SOC对应的锂电池的OCV、锂电池在不同的SOC下对应的锂电池的负极的OCV和所述锂电池在不同SOC下对应的析锂效应压力,确定所述锂电池的负极的极化电压以及所述锂电池的极化电压;建立所述锂电池的温度、所述锂电池的SOH与所述目标参数的对应关系。
- 根据权利要求11所述的装置,其特征在于,所述锂电池在不同SOC下对应的温度和压力包括与所述第一充电倍率对应的第一温度和第一压力、与所述第二充电倍率对应的第二温度和第二压力、以及与所述第三充电倍率对应的第三压力;其中,所述第一压力为发生锂离子脱嵌效应、温度效应和析锂效应所导致的总压力,所述第二压力为发生所述锂离子脱嵌效应和所述温度效应所导致的总压力,所述第三压力为发生所述锂离子脱嵌效应所导致的压力。
- 根据权利要求12所述的装置,其特征在于,所述根据所述锂电池在不同SOC下对应的温度和压力,确定所述锂电池在不同SOC下的析锂效应压力,包括:根据不同SOC下所述第二压力与所述第三压力的差值、以及第二温度,确定所述锂电池的温度效应压力与温度之间的关联关系;所述锂电池的温度效应压力用于指示所述锂电池在不同温度下由温度效应导致的压力变化;根据所述第一温度以及所述关联关系,确定在使用所述第一充电倍率对所述锂电池充电的过程中,所述锂电池在不同SOC下对应的温度效应压力;将所述锂电池在不同SOC下对应的温度效应压力和第三压力之和与第一压力的差值,确定为所述锂电池在不同SOC下对应的析锂效应压力。
- 根据权利要求11-13任一项所述的装置,其特征在于,所述根据所述锂电池在不同SOC对应的锂电池的OCV、锂电池在不同的SOC下对应的锂电池的负极的OCV和所述锂电池在不同SOC下对应的析锂效应压力,确定所述锂电池的负极的极化电压以及所述锂电池的极化电压,包括:将起始SOC对应的锂电池的负极的OCV,确定为所述负极的极化电压;所述起始SOC为所述析锂效应压力的压力值从零转折为非零时对应的SOC;将终止SOC对应的锂电池的OCV与所述锂电池的电压的差值,确定为所述锂电池的极化电压;所述终止SOC为所述析锂效应压力的最大压力值对应的SOC。
- 其中,I为所述锂电池的充电电流,Q为所述锂电池的额定电量,∫ Idt表示所述锂电池在当前时刻的电容量,SOC为所述锂电池的电池荷电状态,V neg为所述锂电池的负极实时电位值,OCV neg为所述锂电池的负极的开路电压,V p,neg为所述锂电池的负极的极化电压,T为所述锂电池的温度,SOH为所述锂电池的电池健康状态,OCV neg(SOC,T,SOH)为OCV neg关于SOC、T、SOH的函数,α为所述锂电池的析锂估算模型中的目标参数,V cell为所述锂电池的电压,OCV cell(SOC,T,SOH)为OCV cell关于SOC、T、SOH的函数,V cell-OCV cell(SOC,T,SOH)表示所述锂电池的极化电压。
- 根据权利要求10-15任一项所述的装置,其特征在于,所述装置还包括析锂告警单元;所述析锂告警单元,用于输出析锂告警信息,所述析锂告警信息包括析锂发生时刻、析锂终止时刻、所述析锂发生时刻对应的SOC、以及析锂严重等级中至少一项;所述析锂严重等级是根据析锂持续时长以及所述锂电池的负极的实时电位值确定的。
- 根据权利要求10-16任一项所述的装置,其特征在于,所述装置还包括电流控制单元;所述电流控制单元,用于根据所述锂电池的负极的实时电位值,调节所述锂电池的充电电流。
- 根据权利要求16或17所述的装置,其特征在于,所述装置还包括电流控制单元;所述电流控制单元,用于根据所述析锂发生时刻以及所述析锂发生时刻对应的SOC,确定所述锂电池的最大安全充电电流。
- 一种电动车辆,其特征在于,所述电动车辆包括锂电池、充放电设备、以及如权利要求10-18中任一项所述的锂电池的析锂检测装置。
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| CN117375129A (zh) * | 2022-07-01 | 2024-01-09 | 比亚迪股份有限公司 | 电池充电方法及车辆 |
| CN115494400A (zh) * | 2022-11-07 | 2022-12-20 | 河南科技学院 | 一种基于集成学习的锂电池析锂状态在线监控方法 |
| CN115494400B (zh) * | 2022-11-07 | 2023-03-28 | 河南科技学院 | 一种基于集成学习的锂电池析锂状态在线监控方法 |
| CN116111221A (zh) * | 2022-11-17 | 2023-05-12 | 中材新材料装备科技(天津)有限公司 | 一种基于图像处理对锂电池健康评估方法 |
| CN116298887A (zh) * | 2023-02-02 | 2023-06-23 | 惠州亿纬锂能股份有限公司 | 锂电池析锂检测方法、装置、电子设备及可读存储介质 |
| CN116125322A (zh) * | 2023-02-22 | 2023-05-16 | 江苏中兴派能电池有限公司 | 一种无损检测电池健康度的方法、装置、设备及介质 |
| CN117054497A (zh) * | 2023-08-11 | 2023-11-14 | 上海轩邑新能源发展有限公司 | 预金属元素化极片的故障确定方法、装置及电子设备 |
| FR3152594A1 (fr) | 2023-09-05 | 2025-03-07 | Psa Automobiles Sa | Procede de controle de courant d’un systeme de batterie en fonction d’une estimation de la concentration en lithium en surface d’une electrode |
| FR3152595A1 (fr) | 2023-09-05 | 2025-03-07 | Psa Automobiles Sa | Procede de charge rapide d’un systeme de batterie |
| FR3154236A1 (fr) | 2023-10-11 | 2025-04-18 | Psa Automobiles Sa | Procede de protection d’un systeme de batterie en fonction d’une estimation d’une quantite de deposition de lithium |
| FR3156537A1 (fr) | 2023-12-12 | 2025-06-13 | Stellantis Auto Sas | Procede de controle d’un courant en fonction d’un compteur a incrementation modulable pour un systeme de batterie |
| FR3161309A1 (fr) | 2024-04-16 | 2025-10-17 | Stellantis Auto Sas | Procede de controle d’un courant de batterie en fonction d’une concentration de lithium calculee par un modele en elements finis |
| CN119024200A (zh) * | 2024-09-10 | 2024-11-26 | 湖北工业大学 | 一种锂离子电池的析锂检测方法 |
Also Published As
| Publication number | Publication date |
|---|---|
| EP4184188A4 (en) | 2023-08-23 |
| CN112703125A (zh) | 2021-04-23 |
| EP4184188B1 (en) | 2024-10-09 |
| CN112703125B (zh) | 2022-04-08 |
| EP4184188A1 (en) | 2023-05-24 |
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