WO2013133361A1 - Bloc accumulateur au lithium, et dispositif électronique, système de charge, et procédé de charge l'utilisant - Google Patents

Bloc accumulateur au lithium, et dispositif électronique, système de charge, et procédé de charge l'utilisant Download PDF

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Publication number
WO2013133361A1
WO2013133361A1 PCT/JP2013/056254 JP2013056254W WO2013133361A1 WO 2013133361 A1 WO2013133361 A1 WO 2013133361A1 JP 2013056254 W JP2013056254 W JP 2013056254W WO 2013133361 A1 WO2013133361 A1 WO 2013133361A1
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Prior art keywords
secondary battery
lithium secondary
negative electrode
battery pack
charging
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English (en)
Japanese (ja)
Inventor
佐藤貴子
上剃春樹
御書至
山田將之
喜多房次
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Maxell Ltd
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Hitachi Maxell Ltd
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Priority to JP2014503536A priority Critical patent/JP5802327B2/ja
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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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/574—Devices or arrangements for the interruption of current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
    • H02J7/50—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries acting upon multiple batteries simultaneously or sequentially
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
    • H02J7/60—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements
    • 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
    • H01M10/44—Methods for charging or discharging
    • H01M10/441—Methods for charging or discharging for several batteries or cells simultaneously or sequentially
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2200/00—Safety devices for primary or secondary batteries
    • H01M2200/10—Temperature sensitive devices
    • H01M2200/106—PTC
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
    • H02J7/60—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements
    • H02J7/61—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements against overcharge
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
    • H02J7/60—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements
    • H02J7/62—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements against overcurrent
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
    • H02J7/60—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements
    • H02J7/63—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements against overdischarge
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
    • 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 invention relates to a lithium secondary battery pack having a protective element connected in a charging / discharging path, and particularly to improvement of quick charge characteristics.
  • the present invention also relates to an electronic device, a charging system, and a charging method using the lithium secondary battery pack thus improved.
  • Non-aqueous secondary batteries such as lithium secondary batteries are widely used as power sources for various portable devices because of their high voltage and high capacity.
  • medium- and large-sized power tools such as electric tools, electric vehicles, and electric bicycles has been spreading.
  • a current value that can be discharged in a fully charged battery in 1 hour is 1 C
  • a current of about 0.7 to 1 C and a predetermined charging end voltage are required.
  • After reaching the end-of-charge voltage switching to CV (constant voltage) charging is performed to decrease the charge current so as to maintain the end-of-charge voltage.
  • Patent Document 1 a method of improving the quick charge characteristics by using a combination of a plurality of positive electrode active materials (Patent Document 1), and using a lithium titanium composite oxide for the negative electrode, high output (load) (Enhancement of characteristics) and a method of enhancing quick charge characteristics (Patent Document 2), and a method of ensuring good battery characteristics even when rapidly charged by adding an insulating inorganic oxide filler separately from the active material to the negative electrode (Patent Document 3) has been proposed.
  • Patent Document 6 it is a method of shortening the charging time by cooling the battery pack to suppress a rapid temperature rise due to rapid charging and enabling charging with a current exceeding 1C.
  • the conventional method described in the above-mentioned patent document for shortening the charging time is expected to further improve the rapid charging characteristics although the corresponding effect is recognized.
  • the present invention has been made in view of the above circumstances, and provides a lithium secondary battery pack having improved quick charge characteristics by appropriately setting parameters relating to a protection element connected in a charge / discharge path. With the goal.
  • Another object of the present invention is to provide an electric device, a charging system, and a charging method using such a lithium secondary battery pack.
  • the lithium secondary battery pack of the present invention includes a lithium secondary battery having a non-aqueous electrolyte and an electrode group in which a positive electrode having a positive electrode mixture layer and a negative electrode having a negative electrode mixture layer are opposed to each other via a separator.
  • the lithium secondary battery pack of the present invention has a protection element portion including the FET in the charge / discharge path of the secondary battery module, and the negative electrode of the lithium secondary battery is
  • a unit cell is composed of a single or a plurality of the lithium secondary batteries connected in parallel, containing a Si-based active material as the negative electrode active material, and a single unit cell or a plurality of the unit cells connected in series
  • a series unit of the minimum unit is configured
  • the secondary battery module is configured of a single unit or a plurality of series units of the minimum unit connected in parallel, and impedance of each protection element constituting the protection element unit
  • the protection element impedance defined by the product of the sum of the above and the number of series units of the minimum unit constituting the secondary battery module is PR ( ⁇ ), and the maximum When the capacity of the series of the unit was Q (Ah), the protective element impedance capacitance rate represented by a ratio PR / Q of the impedance PR for the capacity Q is equal to or is 0.03 or less.
  • the lithium secondary battery pack of the present invention by appropriately setting the protection element impedance capacity index PR / Q, the voltage increase of the secondary battery module during charging is reduced to secure the CC charging area, It is possible to suppress the attenuation of current as much as possible during charging. As a result, it is possible to sufficiently improve the quick charge characteristics while having a high capacity.
  • FIG. 1 is a circuit diagram of a lithium secondary battery pack according to an embodiment of the present invention. Partial sectional view seen from the front schematically showing an example of a lithium secondary battery built in the lithium secondary battery pack Top view of the lithium secondary battery Perspective view of the lithium secondary battery
  • the lithium secondary battery pack of the present invention can take the following aspects based on the above configuration.
  • the unit cell impedance capacity index represented by the ratio CR / Q of the impedance CR to the capacity Q can be 0.04 or less.
  • the protection element impedance capacity index may be 0.02 or less.
  • the slope at 40% SOC of the voltage (mV) -SOC (%) curve obtained when the unit cell is charged with a current value of 1.5C is the voltage per 10% SOC corresponding to the tangent at SOC 40%.
  • the slope may be 90 mV / 10% SOC or less.
  • the capacity per unit area obtained by dividing the capacity of the lithium secondary battery by the facing area between the positive electrode mixture layer and the negative electrode mixture layer is less than 3.0 mAh / cm 2. Can do.
  • the Si content in the Si-based active material may be 0.07 mg / cm 2 or more per unit area of the negative electrode mixture layer.
  • the Si-based active material may be a material containing Si and O as constituent elements (provided that the atomic ratio x of O to Si is 0.5 ⁇ x ⁇ 1.5). it can.
  • the Si-based active material may be configured such that a material containing Si and O as constituent elements is used as a core material, and the surface of the core material is coated with carbon.
  • the lithium secondary battery may include an organic lithium salt having a molecular weight of 2000 or less in an electrolytic solution or an electrode.
  • the lithium secondary battery may include a compound containing an oxalic acid group (—C 2 O 4 —) in the battery.
  • the protection circuit may further include an FET that controls a discharge current of the secondary battery module.
  • the protection element portion may have a PTC element.
  • the ratio of the surface area of the exterior body with respect to the electric energy of the said lithium secondary battery can be set as the structure which is 7 cm ⁇ 2 > / Wh or more.
  • the capacity per unit time in the CC charging period is larger than the charging capacity per unit time in the CV charging period. Therefore, by increasing the CC chargeable area, that is, by increasing the CC charge time and increasing the charge current, the time from the start of charging of the lithium secondary battery pack to the fully charged state can be significantly shortened. .
  • the inventors use a material containing Si and O as constituent elements (however, the atomic ratio x of O with respect to Si is 0.5 ⁇ x ⁇ 1.5) as a negative electrode active material.
  • a lithium secondary battery with a low impedance a battery pack with a capacity of 1.5 Ah was produced, and the conditions for improving the quick charge characteristics were examined.
  • the protection element impedance PR corresponding to the series unit of the minimum unit for controlling the current with the protection element of the battery pack is changed from 0.08 ⁇ to 0.015 ⁇ and charged at a current value of 1.5C, CC charging It was found that it can be charged up to 80% of the battery pack capacity.
  • the definition of the protection element portion impedance PR in this specification will be described in detail later.
  • the negative electrode active material related to the lithium secondary battery is specified, and the protection element impedance PR of the lithium secondary battery pack and the capacity Q of the series unit of the minimum unit are in a specific relationship.
  • the quick charge characteristic is greatly enhanced, for example, compared with the conventional method of charging at a current value of 1 C or less, and the fully charged state is obtained from the start of charging. It has become possible to greatly shorten the time until.
  • FIG. 1 is a circuit diagram showing a configuration of a lithium secondary battery pack according to an embodiment of the present invention.
  • This battery pack incorporates a secondary battery module 1 consisting of a group of lithium secondary batteries 1a (hereinafter abbreviated as “secondary battery 1a”).
  • the secondary battery module 1 is configured by connecting a series part B1 and a series part B2 in parallel.
  • the series part B1 and the series part B2 are each configured by connecting five secondary batteries 1a in series.
  • a PTC (Positive ⁇ Temperature ⁇ Coefficient) element 2 PTC thermistor
  • the PTC element 2 is connected between the negative electrode terminal of the secondary battery module 1 and the external terminal -IN, and has a function of cutting off current according to a rise in temperature.
  • the protection circuit 3 includes FETs (field effect transistors) 4a and 4b and a control unit 5 and has a function of protecting the lithium secondary battery from overcharge, overdischarge, and overcurrent during charge / discharge.
  • the FETs 4a and 4b are inserted in series between the PTC element 2 and the external terminal -IN.
  • the FET 4a operates as a switching element for turning on / off the discharge current
  • the FET 4b operates as a switching element for turning on / off the charging current.
  • the control unit 5 includes a voltage detection unit that detects the battery voltage during charging and discharging and the voltage between the FETs 4a and 4b, a switching control unit that controls the operation of the FETs 4a and 4b based on the voltage detected by the voltage detection unit, and the like. Since the control unit 5 may have a well-known configuration, a specific description is omitted.
  • the lithium secondary battery pack having the above configuration can have a structure in which components such as the secondary battery module 1, the PTC element 2, and the protection circuit 3 shown in FIG.
  • FIG. 1 shows a configuration in which the secondary battery module 1 including a large number of secondary batteries 1a is built in.
  • a lithium secondary battery pack configured by a single secondary battery 1a also includes: The present invention can be applied. That is, in the lithium secondary battery pack of the present invention, the number of secondary batteries 1a can be appropriately set according to the required capacity.
  • the feature of the lithium secondary battery pack of the present invention is that the protective element impedance capacity index, the unit cell impedance capacity index, and the like described below are appropriately set based on the basic configuration as described above. is there.
  • each element connected in the charge / discharge path so as to provide a function of controlling a charging current or a discharging current for battery protection is defined as a protection element.
  • the PTC element 2 and the FETs 4 a and 4 b correspond to protection elements, and in the following description, the PTC element 2 and the FETs 4 a and 4 b are collectively described as a protection element unit 6.
  • the FET 4b is used as the protection element, the charging current of the secondary battery module 1 can be controlled.
  • a group of single or multiple secondary batteries 1a connected in parallel is referred to as a “unit cell”.
  • a basic unit that determines the voltage of the secondary battery module 1 including a single unit cell or a plurality of the unit cells connected in series is defined as a “minimum unit series part”. Therefore, the secondary battery module 1 is comprised by the serial part of the minimum unit of single or several connected in parallel.
  • the group of the secondary battery 1a which comprises a secondary battery module is handled as a structure where the "minimum unit series part" by which an electric current is controlled by a protection element was connected in parallel.
  • each of the series part B ⁇ b> 1 and the series part B ⁇ b> 2 in the secondary battery module 1 corresponds to a “minimum unit series part” in which current is controlled by the protection element group 6.
  • the series part B1 is configured by connecting a plurality of secondary batteries 1a in series.
  • a secondary unit connected in parallel is used as a series unit of the minimum unit to which the present invention is applied.
  • a plurality of battery groups connected in series is also included.
  • each secondary battery 1a is a unit cell.
  • the secondary battery module 1 may be composed of one secondary battery 1a.
  • the “unit cell” is composed of a single secondary battery 1a
  • the “series unit of minimum unit” is Consists of “unit cells”
  • the secondary battery module 1 is composed of a single “series unit of minimum units”.
  • Protective element impedance capacity index is defined as follows for each series unit of the smallest unit. First, when the protection element unit controls a plurality of minimum unit series units having the same capacity in parallel, it is as follows. That is, the protection element group impedance PR ( ⁇ ) is defined as the product of the total impedance of each protection element and the number of the minimum unit series parts for each of the minimum unit series parts. In the case of partial parallel control, only the range to be collectively controlled is multiplied by the number of serial units of the minimum unit to be controlled and used in total. Further, the capacity of the series unit of the minimum unit is assumed to be Q (Ah). The protection element impedance capacity index is defined as a ratio of the protection element group impedance PR to the minimum unit series capacity Q, PR / Q ( ⁇ / Ah).
  • the feature of the present invention is that the impedance of the protective element, the capacitance of the series unit of the minimum unit, etc. are set so that the protective element impedance capacity index PR / Q is 0.03 or less.
  • the protective element impedance capacity index PR / Q is preferably 0.02 or less, more preferably 0.012 or less.
  • the protection element part impedance PR ( ⁇ ) more generally affects the current of each minimum unit series part by the actual impedance of each of the protection unit parts for each of the minimum unit series part. It is defined as the total value corresponding to the ratio. This definition is a description applicable to a case where a plurality of series units of the minimum unit have different capacities and are collectively controlled by one protection element unit.
  • the protection element unit impedance PR is obtained with the respective capacitance ratios.
  • QBtotal (Ah) be the total capacity of the series units B1, B2,.
  • the protection element impedance PR for the series part B1 an impedance value obtained by multiplying the value obtained by dividing QBtotal by the capacitance QB1 of the series part B1 by the total of the actual impedances of the protection elements involved in the control is used.
  • the capacity of the series part B1 is 10 Ah, and the capacity of the series part B2 is 5 Ah.
  • the actual resistance of the PTC element 2 is Rp
  • the unit cell impedance capacity index is defined as follows, and is appropriately set for each of the series units of the minimum unit. That is, the impedance of the unit cell included in the secondary battery module is set to CR ( ⁇ ). Similarly to the above, the capacity of the series unit of the minimum unit is Q (Ah).
  • the unit cell impedance capacity index is expressed as CR / Q ( ⁇ / Ah), which is the ratio of the unit cell impedance CR ( ⁇ ) to the capacity Q of the series unit of the minimum unit.
  • the impedance CR of the unit cell, the capacitance Q of the series unit of the minimum unit, etc. it is preferable to set the impedance CR of the unit cell, the capacitance Q of the series unit of the minimum unit, etc. so that the unit cell impedance capacity index CR / Q is 0.04 or less. . More preferably, the unit cell impedance capacity index CR / Q is 0.03 or less, and more preferably 0.025 or less.
  • the protective element impedance capacity index PR / Q is preferably as small as possible, but is usually 0.002 or more because of technical limitations.
  • the unit cell impedance capacity index CR / Q is preferably as small as possible, but is usually 0.001 or more because of technical limitations.
  • the impedance Z for calculating the protection element impedance capacity index PR / Q or the unit cell impedance capacity index CR / Q defined in this specification is measured using an LCR meter under the conditions of 25 ° C. and 1 kHz. Use the value.
  • the capacitance Q of the series unit of the minimum unit for calculating the protection element impedance capacity index PR / Q or the unit cell impedance capacity index CR / Q a value obtained by the following method is used. That is, after the unit cell of the minimum series unit defined as described above is charged with a constant current at a current value of 1.0 C at 25 ° C. and reaches a full charge voltage (4.2 V in the example), Charging is performed at a constant voltage, and charging is terminated when the total charging time reaches 2.5 hours. The unit cell after charging is discharged at 0.2 C. When the discharge end voltage (3 V in the example) is reached, the discharge is stopped and the amount of discharged electricity is obtained. In addition, when the main voltage control of the secondary battery module is controlled by the entire voltage of the series unit of the minimum unit, the capacity is obtained by converting into the voltage per unit cell.
  • the protection element impedance capacity index PR / Q can be adjusted by adjusting the protection element impedance PR corresponding to the minimum series unit and the minimum unit series capacity Q, respectively.
  • Various methods are known as methods for adjusting the capacity Q of the series unit of the minimum unit, that is, the unit cell capacity of the lithium secondary battery. In the present invention, these can be adopted within a range not impairing the effects of the present invention. .
  • a higher capacity Si-based active material than a carbon material widely used as a negative electrode active material for a lithium secondary battery is used. Although used in part, this can also be used as a method of adjusting the unit cell capacity of the lithium secondary battery pack.
  • a method for adjusting the protection element portion impedance PR there is a method of using a PTC element as a protection element and a FET having a small resistance value for each of the FETs included in the protection circuit.
  • PTC elements and FETs are used in conventional lithium secondary battery packs for mobile phones (lithium secondary battery packs with a capacity that can be fully charged if charged for 1 hour at a current value of 1C or less). It is preferable to select one having a resistance value lower than that of the used one, and particularly when a FET having a low resistance value is used, it greatly contributes to a reduction in impedance of the entire lithium secondary battery pack.
  • the charging current value As described above, in order to improve the quick charge characteristics of the lithium secondary battery pack, it is preferable to increase the charging current value and increase the chargeable region by CC charging in CC-CV charging. Specifically, it is preferable that the capacity that can be charged by CC charging exceeds 80% of the capacity of the lithium secondary battery pack.
  • the lithium secondary battery pack has an SOC of 40% of a voltage (mV) -SOC (ratio of charge capacity to standard capacity) (%) curve obtained when a unit cell is charged with a current value of 1.5 C.
  • the inclination k40 at is preferably small.
  • the slope k40 is obtained by extending the tangent line at SOC 40% of the voltage-SOC curve from SOC 35% to SOC 45%, obtaining a voltage difference at each SOC, and calculating the value as a voltage increase value (mV) with respect to a change in SOC 10%. ). Therefore, in this specification, the slope k40 is described as a voltage increase value (mV) / 10% SOC.
  • the slope k40 is preferably 90 (mV) / 10% SOC or less, more preferably 50 mV / 10% SOC or less, and still more preferably 10 mV / 10% SOC or less. Further, the inclination k40 is usually larger than 1 mV / 10% SOC.
  • the inclination k40 described above can be reduced by using a Si-based active material for the negative electrode active material related to the lithium secondary battery constituting the lithium secondary battery pack. Further, in the negative electrode of the lithium secondary battery, the content of Si contained in the Si-based active material per area of the negative electrode mixture layer (area in plan view; the same applies hereinafter) is adjusted to a value described later. Therefore, it can adjust more favorably.
  • a lithium secondary battery includes an electrode body in which a positive electrode having a positive electrode mixture layer and a negative electrode having a negative electrode mixture layer are opposed to each other via a separator, and a nonaqueous electrolyte.
  • the negative electrode of the lithium secondary battery for example, one having a structure having a negative electrode mixture layer containing a negative electrode active material and a binder on one side or both sides of a current collector is used.
  • Si-based active materials such as alloys, oxides, and carbides containing Si as a constituent element are used.
  • Si-based active materials such as alloys, oxides, and carbides containing Si as a constituent element are used.
  • a lithium secondary battery with little voltage increase during charging can be formed, which is suitable for a lithium secondary battery pack.
  • Any one of Si-based active materials may be used, or two or more of them may be used in combination.
  • the Si-based active materials it is preferable to use a material containing Si and O as constituent elements (however, the atomic ratio x of O to Si is 0.5 ⁇ x ⁇ 1.5).
  • Such materials containing Si and O as constituent elements include Si and other metals (for example, B, Al, Ga, In, Ge, Sn, P, Bi, etc.) in addition to Si oxides.
  • a composite oxide may also be used. Further, it may contain a crystallite or amorphous phase of Si or another metal.
  • the atomic ratio x of O to Si should satisfy 0.5 ⁇ x ⁇ 1.5.
  • SiOx a material having a structure in which a minute Si phase is dispersed in an amorphous SiO 2 matrix is particularly preferably used (hereinafter referred to as “SiOx”). ").
  • a material having such a structure for example, in X-ray diffraction analysis, a peak due to the presence of Si (microcrystalline Si) may not be observed, but when observed with a transmission electron microscope, the presence of fine Si Can be confirmed.
  • a conductive aid such as a carbon material is required for use as a negative electrode active material.
  • a material containing Si and O as constituent elements is used as a core material, and carbon is formed on the surface thereof. It is preferable to form a coating layer. In this case, since the conductive network in the negative electrode mixture layer containing the negative electrode active material can be satisfactorily formed, the load characteristics of the lithium secondary battery can be improved.
  • the material that contains Si and O as constituent elements for the core material can be used as a material produced by a conventionally known method.
  • a material containing the above-described Si and O as a core material as constituent elements and, if necessary, a carbon material are dispersed in a dispersion medium such as ethanol, and the obtained dispersion is sprayed at 50 to 300 ° C. And drying to prepare composite particles containing a plurality of particles. Further, the composite particles may be prepared by a mechanical method using a vibration mill or the like.
  • the prepared composite particles (core material) are heated under a hydrocarbon gas stream such as methane or toluene, and carbon produced by pyrolysis of the hydrocarbon gas is deposited on the surface of the composite particles.
  • a material in which the surface of the core material is coated with carbon can be obtained.
  • covered the surface of the core material with carbon can also be obtained by the method of spraying the dispersion liquid containing petroleum-type pitch on the surface of the prepared composite particle (core material), and baking.
  • the content is 10 to 30% by mass in the total amount (100% by mass) of the material in which the surface of the core material is coated with carbon.
  • the core material is SiOx
  • the Raman spectrum (measured laser wavelength: 532 nm) of the material in which the surface of the core material is coated with carbon the peak intensity (I 510 ) of 510 cm ⁇ 1 derived from Si and C
  • the intensity ratio I 510 / I 1343 with the peak intensity (I 1343 ) of 1343 cm ⁇ 1 derived from carbon is preferably 0.25 or less.
  • the intensity ratio I 510 / I 1343 in the Raman spectrum referred to in this specification is a mapping measurement (measurement range: 80 ⁇ 80 ⁇ m, 2 ⁇ m step) of a material in which the surface of the core material is coated with carbon by microscopic Raman spectroscopy. all spectra are average inner, a value determined by the intensity ratio between the peak (1343cm -1) derived from the C-peak derived from Si (510cm -1).
  • the crystallite size of the Si phase in SiOx is optimized. In this way, it is possible to improve the storage characteristics while maintaining the feature of high capacity.
  • the half width of the (111) diffraction peak of Si obtained by the X-ray diffraction method using CuK ⁇ rays is preferably 2.5 ° or less.
  • the Si phase crystallite size in the SiOx core material is too large, the initial charge / discharge capacity may be reduced, so the half width of the Si (111) diffraction peak determined by the X-ray diffraction method Is preferably 0.5 ° or more.
  • the average particle diameter (D) is selected from the viewpoint of suppressing the capacity reduction after repeatedly charging and discharging the lithium secondary battery pack. 50 ) is preferably 0.5 ⁇ m or more. From the viewpoint of suppressing the expansion of the negative electrode caused by charging and discharging of the lithium secondary battery pack, the average particle diameter (D 50), is preferably 20 ⁇ m or less.
  • the average particle size of a material in which the surface of a core material made of a material containing Si and O as a constituent element is coated with carbon is measured using a laser scattering particle size distribution meter (for example, “LA-920” manufactured by Horiba, Ltd.). Is a value measured by dispersing in a solvent.
  • a laser scattering particle size distribution meter for example, “LA-920” manufactured by Horiba, Ltd.
  • an active material other than the Si-based active material can be used together with the Si-based active material as the negative electrode active material.
  • a graphite material is preferable.
  • the graphite material those conventionally used for lithium secondary batteries are suitable.
  • the content of the Si-based active material in the negative electrode active material is 0.5% by mass or more in terms of the amount of Si contained in the Si-based active material from the viewpoint of further improving the quick charge characteristics of the lithium secondary battery pack. Is preferably 1% by mass or more, more preferably 2% by mass or more.
  • the content of the Si-based active material in the negative electrode active material is 2% by mass or more in terms of the amount of Si contained in the Si-based active material, the effect of improving the quick charge characteristics of the lithium secondary battery pack is particularly good. Become.
  • the Si-based active material since the Si-based active material has a large volume change amount due to charging / discharging, there is a concern that the capacity of the lithium secondary battery pack may be reduced by repeating charging / discharging.
  • the Si-based active material in the negative electrode active material The content of is the amount of Si contained in the Si-based active material, and is preferably 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less.
  • binder relating to the negative electrode mixture layer examples include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylate, polyimide, polyamideimide, Etc. are preferably used.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • polyacrylate polyimide
  • polyamideimide Etc.
  • the negative electrode includes, for example, a negative electrode active material and a binder, and a paste or slurry negative electrode mixture in which a conductive auxiliary agent is dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP) or water as necessary.
  • NMP N-methyl-2-pyrrolidone
  • Prepare a composition containing the binder (however, the binder may be dissolved in a solvent), apply it to one or both sides of the current collector, dry it, and then press it as necessary. Is done.
  • the negative electrode is not limited to those manufactured by this manufacturing method, and may be manufactured by other manufacturing methods.
  • the thickness of the negative electrode mixture layer is preferably 10 to 100 ⁇ m per side of the current collector, and the density of the negative electrode mixture layer (the mass of the negative electrode mixture layer per unit area laminated on the current collector) , Calculated from the thickness) is preferably 1.0 to 1.9 g / cm 3 .
  • the amount of the negative electrode active material is preferably 80 to 99% by mass
  • the amount of the binder is preferably 1 to 20% by mass
  • a conductive assistant is used. In that case, the amount is preferably 1 to 10% by mass.
  • the content of Si contained in the Si-based active material per unit area of the negative electrode mixture layer is 0.007 mg / cm 2 or more from the viewpoint of further improving the quick charge characteristics of the lithium secondary battery pack. Preferably, it is 0.018 mg / cm 2 or more, and more preferably 0.100 mg / cm 2 or more.
  • the negative electrode current collector a foil made of copper or nickel, a punching metal, a net, an expanded metal, or the like can be used, but a copper foil is usually used.
  • the upper limit of the thickness is preferably 30 ⁇ m, and the lower limit is 5 ⁇ m in order to ensure mechanical strength. Is desirable.
  • the positive electrode of the lithium secondary battery for example, one having a structure in which a positive electrode mixture layer containing a positive electrode active material, a conductive additive and a binder is provided on one side or both sides of a current collector is used.
  • Li-containing transition metal oxide capable of occluding and releasing Li (lithium) ions.
  • the Li-containing transition metal oxide include those conventionally used in lithium secondary batteries, specifically, Li y CoO 2 (where 0 ⁇ y ⁇ 1.1), Li z NiO 2 (where 0 ⁇ z ⁇ 1.1), Li e MnO 2 (where 0 ⁇ e ⁇ 1.1), Li a Co b M 1 1-b O 2 ( M 1 is at least one metal element selected from the group consisting of Mg, Mn, Fe, Ni, Cu, Zn, Al, Ti, Ge, and Cr, and 0 ⁇ a ⁇ 1.1, 0 ⁇ B ⁇ 1.0), Li c Ni 1-d M 2 d O 2 (where M 2 is made of Mg, Mn, Fe, Co, Cu, Zn, Al, Ti, Ge, and Cr) At least one metal element selected from the group, 0 ⁇ c ⁇ 1.1, 0
  • the same binders as those exemplified above as the binder for the negative electrode mixture layer can be used.
  • the conductive auxiliary agent related to the positive electrode mixture layer for example, graphite (graphite carbon material) such as natural graphite (flaky graphite), artificial graphite; acetylene black, ketjen black, channel black, furnace black, Examples thereof include carbon blacks such as carbon blacks such as lamp black and thermal black; carbon fibers.
  • the positive electrode for example, a paste-like or slurry-like positive electrode mixture-containing composition in which a positive electrode active material, a binder, and a conductive additive are dispersed in a solvent such as NMP is prepared (however, the binder is dissolved in the solvent). It may be manufactured through a step of applying a press treatment as necessary after applying this to one or both sides of the current collector and drying it.
  • the positive electrode is not limited to those manufactured by this manufacturing method, and may be manufactured by other manufacturing methods.
  • the thickness of the positive electrode mixture layer is preferably, for example, 10 to 100 ⁇ m per side of the current collector, and the density of the positive electrode mixture layer (the mass of the positive electrode mixture layer per unit area laminated on the current collector, (Calculated from the thickness) is preferably 3.0 to 4.5 g / cm 3 .
  • the amount of the positive electrode active material is preferably 60 to 95% by mass
  • the amount of the binder is preferably 1 to 15% by mass
  • the amount of the conductive auxiliary agent Is preferably 3 to 20% by mass.
  • the positive electrode current collector As the positive electrode current collector, the same ones used for positive electrodes of conventionally known lithium secondary batteries can be used.
  • an aluminum foil having a thickness of 10 to 30 ⁇ m is preferable.
  • the negative electrode and the positive electrode described above are laminated with a separator to be described later interposed therebetween, and a laminated electrode body in which these are opposed via a separator, or a laminated body obtained by laminating a negative electrode and a positive electrode via a separator are spirally formed.
  • the wound electrode body is used for a lithium secondary battery.
  • the capacity (mAh) is obtained by dividing the capacity (mAh) by the facing area between the positive electrode mixture layer and the negative electrode mixture layer (the area of the portion facing through the separator, unit: cm 2 ).
  • capacitance per unit area (hereinafter, referred to as "electrode capacity per opposing area”) is preferably less than 3.3mAh / cm 2, more preferably less than 3.0mAh / cm 2, 2.8mAh More preferably, it is less than / cm 2 .
  • the capacity per electrode facing area in the lithium secondary battery is preferably 1 mAh / cm 2 or more.
  • the capacity of the lithium secondary battery used for calculating the capacity per electrode facing area is a value obtained by the following method. That is, a lithium secondary battery is charged at a constant current at a current value of 1.0 C at 25 ° C., charged at a constant voltage after reaching a full charge voltage (4.2 V in the example), and the total charging time is Charging is terminated when 2.5 hours are reached. About the lithium secondary battery after charge, it discharges at 0.2C, and if discharge end voltage (3V in an Example) is reached, discharge will be stopped and discharge electric charge will be calculated
  • the capacity per electrode facing area is the capacity of the lithium secondary battery by the area of the positive electrode mixture layer. The divided value.
  • the ratio P / N between the mass P of the positive electrode active material and the mass N of the negative electrode active material is preferably 1.0 to 3.6.
  • the deterioration of the charge / discharge cycle characteristics of the lithium secondary battery pack due to the pulverization of the negative electrode active material particles can be suppressed.
  • a high battery capacity is securable by making P / N ratio into 1.0 or more.
  • the separator has sufficient strength and can hold a large amount of nonaqueous electrolyte, and has a thickness of 5 to 50 ⁇ m and an opening ratio of 30 to 70%.
  • a microporous membrane made of polyolefin such as PP) can be used.
  • the microporous membrane constituting the separator may be, for example, one using only PE or one using PP only, may contain an ethylene-propylene copolymer, and may be made of PE.
  • a laminate of a membrane and a PP microporous membrane may be used.
  • the separator of the lithium secondary battery is mainly composed of a porous layer (A) mainly composed of a resin having a melting point of 140 ° C. or lower and a resin having a melting point of 150 ° C. or higher or an inorganic filler having a heat resistant temperature of 150 ° C. or higher.
  • “melting point” means a melting temperature measured using a differential scanning calorimeter (DSC) in accordance with the provisions of JIS K 7121.
  • “Heat resistant temperature is 150 ° C. or higher” means at least 150 ° C. This means that no deformation such as softening is observed.
  • the porous layer (A) according to the above-mentioned laminated separator is mainly for ensuring a shutdown function, and the melting point of the resin, which is a component in which the lithium secondary battery is the main component of the porous layer (A)
  • the resin related to the porous layer (A) melts and closes the pores of the separator, thereby causing a shutdown that suppresses the progress of the electrochemical reaction.
  • Examples of the resin having a melting point of 140 ° C. or lower as the main component of the porous layer (A) include PE.
  • Examples of the form include a microporous film used for a lithium secondary battery, and a base material such as a nonwoven fabric coated with PE particles.
  • the volume of the resin having a main melting point of 140 ° C. or less is 50% by volume or more, and more preferably 70% by volume or more.
  • the volume is 100% by volume.
  • the porous layer (B) according to the above-described laminated separator has a function of preventing a short circuit due to direct contact between the positive electrode and the negative electrode even when the internal temperature of the lithium secondary battery is increased. Its function is ensured by a resin having a melting point of 150 ° C. or higher or an inorganic filler having a heat resistant temperature of 150 ° C. or higher. That is, when the battery becomes high temperature, even if the porous layer (A) shrinks, the porous layer (B) which does not easily shrink can directly generate positive and negative electrodes that can be generated when the separator is thermally contracted. It is possible to prevent a short circuit due to the contact. Moreover, since this heat-resistant porous layer (B) functions as a skeleton of the separator, thermal contraction of the porous layer (A), that is, thermal contraction of the entire separator itself can be suppressed.
  • the porous layer (B) is mainly composed of a resin having a melting point of 150 ° C. or higher
  • the form thereof is, for example, a microporous film formed of a resin having a melting point of 150 ° C. or higher (for example, made of the aforementioned PP).
  • the composition for forming a porous layer (B) containing fine particles of a resin having a melting point of 150 ° C. or higher is applied to the porous layer (A).
  • An application lamination type form in which a porous layer (B) containing fine particles of a resin having a melting point of 150 ° C. or higher is laminated is applied to (A).
  • Examples of the resin constituting the fine particles of the resin having a melting point of 150 ° C. or higher include PP; crosslinked polymethyl methacrylate, crosslinked polystyrene, crosslinked polydivinylbenzene, crosslinked styrene-divinylbenzene copolymer, polyimide, melamine resin, phenol resin, Examples include various cross-linked polymers such as benzoguanamine-formaldehyde condensate; polysulfone; polyether sulfone; polyphenylene sulfide; polytetrafluoroethylene; polyacrylonitrile; aramid;
  • the average particle size of the fine particles of the resin having a melting point of 150 ° C. or higher is, for example, preferably 0.01 ⁇ m or more, more preferably 0.1 ⁇ m or more, preferably 10 ⁇ m or less, more preferably 2 ⁇ m or less. is there.
  • the average particle diameter of the fine particles referred to in this specification is measured by, for example, using a laser scattering particle size distribution meter (for example, “LA-920” manufactured by HORIBA, Ltd.) by dispersing these fine particles in a medium that does not dissolve the resin.
  • the total volume of the constituent components of the porous layer (B) (the whole excluding pores) Product) is 50% by volume or more, preferably 70% by volume or more, more preferably 80% by volume or more, and still more preferably 90% by volume or more.
  • the porous layer (B) is mainly composed of an inorganic filler having a heat resistant temperature of 150 ° C. or higher
  • a composition for forming the porous layer (B) containing an inorganic filler having a heat resistant temperature of 150 ° C. or higher (coating liquid) ) Is applied to the porous layer (A), and a porous layer (B) containing an inorganic filler having a heat resistant temperature of 150 ° C. or higher is laminated.
  • the inorganic filler according to the porous layer (B) has a heat-resistant temperature of 150 ° C. or higher, is stable with respect to the non-aqueous electrolyte constituting the lithium secondary battery, and is oxidized and reduced within the operating voltage range of the lithium secondary battery.
  • fine particles are preferable from the viewpoint of dispersion, and alumina, silica, and boehmite are preferable.
  • Alumina, silica, and boehmite have high oxidation resistance, and the particle size and shape can be adjusted to desired values, etc., making it easy to accurately control the porosity of the porous layer (B). It becomes.
  • the thing of the said illustration may be used individually by 1 type, and may use 2 or more types together, for example.
  • an inorganic filler having a heat resistant temperature of 150 ° C. or higher and a resin fine particle having a melting point of 150 ° C. or higher may be used in combination.
  • a substantially spherical shape (a true spherical shape is included), a substantially ellipsoid shape (including an ellipsoid shape), plate shape, etc.
  • Various shapes can be used.
  • the average particle diameter of the inorganic filler having a heat resistant temperature of 150 ° C. or higher (the average particle diameter of the plate-like filler and the other shape filler. The same applies hereinafter) of the porous layer (B) is too small, the ion permeability is high. Since it falls, it is preferable that it is 0.3 micrometer or more, and it is more preferable that it is 0.5 micrometer or more.
  • the average particle diameter is preferably 5 ⁇ m or less, and more preferably 2 ⁇ m or less.
  • the average particle diameter of the inorganic filler having a heat resistant temperature of 150 ° C. or higher as used herein is an average particle diameter (D 50 ) determined by the same method as the average particle diameter of resin fine particles having a melting point of 150 ° C. or higher.
  • the amount in the porous layer (B) is the amount of the porous layer (B). Is 50% by volume or more, preferably 70% by volume or more, more preferably 80% by volume or more, and 90% by volume or more. More preferably it is.
  • the inorganic filler having a heat resistant temperature of 150 ° C. or higher and the fine particles of the resin having a melting point of 150 ° C. or higher are used in combination, it is sufficient that both of them form the main body of the porous layer (B).
  • the total amount of these components may be 50% by volume or more in the total volume of the constituent components of the porous layer (B) (total volume excluding the pores), and 70% by volume or more. It is preferable to make it 80% by volume or more, more preferably 90% by volume or more. Thereby, the effect similar to the case where the inorganic filler in a porous layer (B) is made into high content as mentioned above is securable.
  • porous layer (B) fine particles of a resin having a melting point of 150 ° C. or higher or inorganic fillers having a heat resistant temperature of 150 ° C. or higher are bound, or the porous layer (B) and the porous layer (A) It is preferable to contain an organic binder in order to integrate them.
  • Organic binders include ethylene-vinyl acetate copolymers (EVA, structural units derived from vinyl acetate of 20 to 35 mol%), ethylene-acrylic acid copolymers such as ethylene-ethyl acrylate copolymers, fluorine-based binders Examples include rubber, SBR, CMC, hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinyl pyrrolidone (PVP), cross-linked acrylic resin, polyurethane, and epoxy resin.
  • a heat-resistant binder having a heat-resistant temperature is preferably used.
  • the organic binder those exemplified above may be used singly or in combination of two or more.
  • highly flexible binders such as EVA, ethylene-acrylic acid copolymer, fluorine rubber, and SBR are preferable.
  • highly flexible organic binders include Mitsui DuPont Polychemical's “Evaflex Series (EVA)”, Nihon Unicar's EVA, Mitsui DuPont Polychemical's “Evaflex-EAA Series (Ethylene).
  • EVA Evaflex Series
  • EVA Nihon Unicar's EVA
  • -Acrylic acid copolymer) ", EEA of Nihon Unicar”
  • Daiel Latex Series (Fluororubber) of Daikin Industries
  • TRD-2001 (SBR) of JSR
  • BM-400B Nippon Zeon "
  • the above-mentioned organic binder is used for the porous layer (B), it may be used in the form of an emulsion dissolved or dispersed in a solvent of a composition for forming a porous layer (B) described later.
  • the above-mentioned coated laminate type separator is, for example, a porous layer (B) forming composition (liquid composition such as slurry) containing fine particles of a resin having a melting point of 150 ° C. or higher or an inorganic filler having a heat resistant temperature of 150 ° C. or higher.
  • composition liquid composition such as slurry
  • an inorganic filler having a heat resistant temperature of 150 ° C. or higher.
  • the composition for forming the porous layer (B) contains fine particles of a resin having a melting point of 150 ° C. or higher or an inorganic filler having a heat resistant temperature of 150 ° C. or higher, and, if necessary, an organic binder and the like. Including the medium. The same shall apply hereinafter.)
  • the organic binder can be dissolved in a solvent.
  • the solvent used for the composition for forming the porous layer (B) may be any solvent that can uniformly disperse the inorganic filler and the like and can uniformly dissolve or disperse the organic binder.
  • organic solvents such as aromatic hydrocarbons such as toluene, furans such as tetrahydrofuran, and ketones such as methyl ethyl ketone and methyl isobutyl ketone are preferably used.
  • alcohols ethylene glycol, propylene glycol, etc.
  • various propylene oxide glycol ethers such as monomethyl acetate may be appropriately added to these solvents.
  • water may be used as a solvent.
  • alcohols methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, etc.
  • the composition for forming the porous layer (B) has a solid content containing, for example, 10 to 80% by mass of resin fine particles having a melting point of 150 ° C. or higher, an inorganic filler having a heat resistant temperature of 150 ° C. or higher, and an organic binder. It is preferable to do.
  • the porous layer (A) and the porous layer (B) do not have to be one each, and a plurality of layers may be present in the separator.
  • the porous layer (A) may be arranged on both sides of the porous layer (B), or the porous layer (B) may be arranged on both sides of the porous layer (A).
  • increasing the number of layers may increase the thickness of the separator and increase the internal resistance of the battery or decrease the energy density. Therefore, it is not preferable to increase the number of layers.
  • the total number of layers of the porous layer (A) and the porous layer (B) is preferably 5 or less.
  • the thickness of a separator (a separator made of a microporous membrane made of polyolefin or the laminated separator) according to a lithium secondary battery is preferably 10 to 30 ⁇ m.
  • the thickness of the porous layer (B) [when the separator has a plurality of porous layers (B), the total thickness] From the viewpoint of more effectively exerting the action, it is preferably 3 ⁇ m or more. However, if the porous layer (B) is too thick, the energy density of the battery may be lowered. Therefore, the thickness of the porous layer (B) is preferably 8 ⁇ m or less.
  • the thickness of the porous layer (A) [when the separator has a plurality of porous layers (I), the total thickness thereof. same as below. ] Is preferably 6 ⁇ m or more, more preferably 10 ⁇ m or more, from the viewpoint of more effectively exerting the above-described action (particularly the shutdown action) due to the use of the porous layer (A).
  • the porous layer (A) is too thick, there is a possibility that the energy density of the battery may be lowered.
  • the force that the porous layer (A) tends to shrink is increased, and the heat of the entire separator is increased. There is a possibility that the effect of suppressing the shrinkage becomes insufficient. Therefore, the thickness of the porous layer (A) is preferably 25 ⁇ m or less, more preferably 20 ⁇ m or less, and further preferably 14 ⁇ m or less.
  • the porosity of the separator as a whole is preferably 30% or more in a dry state in order to ensure the amount of electrolyte retained and to improve ion permeability.
  • the separator porosity is preferably 70% or less in a dry state.
  • the porosity of the separator: P (%) can be calculated by obtaining the sum for each component i from the thickness of the separator, the mass per area, and the density of the constituent components using the following equation (1).
  • a i ratio of component i when the total mass is 1
  • ⁇ i density of component i (g / cm 3 )
  • m mass per unit area of the separator ( g / cm 2 )
  • t thickness (cm) of the separator.
  • m is the mass per unit area (g / cm 2 ) of the porous layer (A)
  • t is the thickness of the porous layer (A) ( cm)
  • the porosity: P (%) of the porous layer (A) can also be obtained using the equation (1).
  • the porosity of the porous layer (A) obtained by this method is preferably 30 to 70%.
  • m is the mass per unit area (g / cm 2 ) of the porous layer (B)
  • t is the thickness of the porous layer (B) ( cm)
  • the porosity: P (%) of the porous layer (B) can also be obtained using the equation (1).
  • the porosity of the porous layer (B) obtained by this method is preferably 20 to 60%.
  • the separator one having high mechanical strength is preferable, and for example, the piercing strength is preferably 3N or more.
  • the negative electrode active material used in the lithium secondary battery according to the present invention has a large volume expansion / contraction during charging / discharging, for example, by limiting the P / N ratio to 1.0 to 3.6. Although expansion and contraction can be suppressed and charge / discharge cycle characteristics can be improved, mechanical damage is also applied to the facing separator due to expansion / contraction of the entire negative electrode by repeating charge / discharge cycles. If the piercing strength of the separator is 3N or more, good mechanical strength is ensured, and mechanical damage to the separator can be reduced.
  • Examples of the separator having a puncture strength of 3N or more include the above-described laminated separator, and in particular, an inorganic filler having a heat resistant temperature of 150 ° C. or higher in the porous layer (A) mainly composed of a resin having a melting point of 140 ° C. or lower.
  • a separator in which a porous layer (B) containing as a main component is laminated is preferable. This is presumably because the mechanical strength of the above-described inorganic filler is high, so that the mechanical strength of the entire separator can be increased by supplementing the mechanical strength of the porous layer (A).
  • the piercing strength can be measured by the following method. That is, the separator is fixed on a plate having a hole with a diameter of 2 inches so as not to be wrinkled or bent, and a semispherical metal pin having a tip diameter of 1.0 mm is lowered onto the measurement sample at a speed of 120 mm / min. And measure the force when the separator is perforated five times. And an average value is calculated
  • the porous layer (A) mainly composed of a resin having a melting point of 140 ° C. or lower is used.
  • a separator in which a porous layer (B) mainly containing an inorganic filler having a heat resistant temperature of 150 ° C. or higher is used, it is preferable to dispose the porous layer (B) so as to face at least the positive electrode. .
  • the oxidation of the separator by the positive electrode can be suppressed better, It is also possible to improve the storage characteristics and charge / discharge cycle characteristics of the battery at high temperatures. Further, when an additive such as vinylene carbonate or cyclohexylbenzene is added to the non-aqueous electrolyte (described later), there is a possibility that the positive electrode side is coated to clog the pores of the separator and the battery characteristics are remarkably deteriorated. Therefore, an effect of suppressing clogging of the pores can be expected by causing the relatively porous porous layer (B) to face the positive electrode.
  • an additive such as vinylene carbonate or cyclohexylbenzene
  • the porous layer (A) faces the negative electrode, so that, for example, the porous layer is shut down at the time of shutdown.
  • the thermoplastic resin melted from (A) is suppressed from being absorbed by the electrode mixture layer, and can be efficiently used to close the pores of the separator.
  • non-aqueous electrolyte related to the lithium secondary battery examples include a non-aqueous electrolyte prepared by dissolving an inorganic lithium salt, an organic lithium salt, or both in a solvent described below.
  • Examples of the solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ⁇ -Butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, tri Methoxymethane, dioxolane derivative, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether , An aprotic organic solvent such as 1,3-propane sultone may be used alone or in combination.
  • Examples of the inorganic lithium salt LiClO 4, LiBF 4, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, lower aliphatic carboxylic acids Li, LiAlCl 4, LiCl, LiBr ,
  • LiI, chloroborane Li, and tetraphenylborate Li can be used.
  • organic lithium salt examples include LiCF 3 SO 3 , LiCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiC n F 2n + 1
  • SO 3 (n ⁇ 2), LiN (RfOSO 2 ) 2 [where Rf is a fluoroalkyl group] and the like can be used.
  • the concentration of the lithium salt in the nonaqueous electrolytic solution for example, preferably from 0.2 ⁇ 3.0mol / dm 3, more preferably from 0.5 ⁇ 1.5mol / dm 3, 0.9 More preferably, it is ⁇ 1.3 mol / dm 3 .
  • nonaqueous electrolytes related to lithium secondary batteries at least one chain carbonate selected from methyl carbonate, diethyl carbonate and methyl ethyl carbonate, and at least one cyclic carbonate selected from ethylene carbonate and propylene carbonate It is particularly preferable to use a nonaqueous electrolytic solution in which LiPF 6 is dissolved in the solvent to be contained.
  • non-aqueous electrolytes include, for example, anhydrides, sulfonate esters, dinitriles, 1, 3 -Propane sultone, diphenyl disulfide, cyclohexylbenzene, vinylene carbonate (VC), biphenyl, fluorobenzene, t-butylbenzene, cyclic fluorinated carbonate [trifluoropropyl carbonate (TFPC), fluoroethylene carbonate (FEC), etc.], Alternatively, chain fluorinated carbonates [trifluorodimethyl carbonate (TFDMC), trifluorodiethyl carbonate (TFDEC), trifluoroethyl methyl carbonate (TFEMC), etc.], fluorinated ethers [Rf1-OR2: Rf1 Alkyl groups containing fluorine, R2 is organic group
  • phosphate ester is an effective additive that has the effect of suppressing side reactions during storage.
  • the non-aqueous electrolyte contains a fluorine-containing organometallic salt having an oxalic acid group (—O (C ⁇ O) — (C ⁇ O—) O—) or A valent organometallic salt can also be contained.
  • a fluorine-containing organometallic salt having an oxalic acid group —O (C ⁇ O) — (C ⁇ O—) O—
  • a valent organometallic salt can also be contained.
  • Examples of the fluorine-containing organometallic salt having an oxalic acid group include (PF 2 (C 2 O 4 ) 2 ) b M c , (BF 2 ( C 2 O 4)) b M c, M b (PF 4 (C 2 O 4)) , etc. c are exemplified.
  • B and c in these general formulas are numbers determined by the valence of the metal M and the valence of the anion.
  • R 1 is, for example, an organic group such as an alkyl group, an alkylene group, or an aromatic group, and a part or all of hydrogen atoms of these groups may be substituted with fluorine atoms.
  • a is an integer of 2 or more.
  • Y is, for example, a metal base of an acid.
  • Rf is a fluorine-substituted alkyl in group (hereinafter the same), d is 5 an integer (hereinafter the same)], - BF e Rf 3 -e - (e is 3 or less an integer, hereinafter the same), - R g PO 4 - [R is an organic residue A group (hereinafter the same) may be bonded to R 1 , and g is 0 or 1 (hereinafter the same)].
  • Y in the general formula may be only one of the above-described examples, or may be two or more.
  • M in the general formula is a metal element such as an alkali metal, alkaline earth metal, transition metal, or group 13 element, such as Li, Na, K, Mg, Ca, Mn, Al, and the like.
  • Earth metals are desirable, alkali metals are more desirable, and lithium is most desirable. That is, as the polyvalent organic metal salt, a polyvalent organic lithium salt is most desirable.
  • B and c in the above general formula are numbers determined by the valence of the metal M and the valence of [R 1 (Y) a ].
  • the polyvalent organometallic salt represented by the above general formula may contain a hydroxyl group (—OH) or an acid group (—SO 3 H, —CO 2 H, etc.) in the organic group R 1.
  • the number is preferably less than the acid metal base, and more preferably 1/10 or less of the number of the acid metal base.
  • the molecular weight of R 1 in the general formula is preferably 100,000 or less, more preferably 2000 or less, and preferably 500 or less. Most desirable.
  • R 1 in the general formula is preferably 30 or more, more preferably 50 or more, and 70 or more. Most desirable.
  • R 1 is an alkylene or aromatic group, or an organic hybrid mainly containing them, such as —CH 2 CH 2 CH 2 CH 2 —, —CHFCH 2 CH 2 CH 2 —, —CF 2 CF 2 CF 2.
  • CF 2- such as -C h H 2h-i F i- (h and i are integers, h ⁇ 1, i ⁇ 0), -C 6 H 4 -,> C 6 H 3 -, - C 6 H 4 -C 6 H 4 -, - C 6 H 3 F -, - C 6 F 4 - , etc., - (C 6 H 4- j F k) l (C 6 H 4- m F n ) u ⁇ (j, k, l, m, n, u are integers, j ⁇ 0, k ⁇ 0, k ⁇ j, m ⁇ 0, n ⁇ 0, n ⁇ m, l + u ⁇ 1 aromatic group represented as) or,,> C 6 H 3 -C (CF 3) 2 -C 6 H 3 ⁇ ,> C 6 H 3 -CF 3, -C 6 H -C (CF 3) 2 -C 6 H 4 -, R 2 (CH
  • organometallic salt having —SO 3 ⁇ , —CO 2 — or —PO 4 — as Y in an alkylene or aromatic group is exemplified.
  • fluorine-containing organometallic salts or polyvalent metal salts having an oxalic acid group (—O (C ⁇ O) — (C ⁇ O—) O—)
  • LiPF 2 (C 2 O 4 ) 2 LiBF 2 ( C 2 O 4 )
  • the fluorine-containing organometallic salt or polyvalent metal salt having an oxalic acid group may be used for a negative electrode containing SiOC-based active material particles, or may be contained in a negative electrode mixture.
  • the amount of the fluorine-containing organic metal salt or polyvalent metal salt added to the electrolytic solution is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and most preferably 0.2% by weight or more. . On the other hand, if the amount added is too large, the characteristics of the battery deteriorate. Therefore, it is preferably less than 10% by weight, more preferably less than 3% by weight, and most preferably less than 1.5% by weight.
  • the value converted as if the total amount is contained in the electrolytic solution may be adjusted to be in the above range.
  • a lithium secondary battery obtained by adding a gelling agent such as a known polymer to the above-described non-aqueous electrolyte to form a gel can also be used as the non-aqueous electrolyte.
  • the shape of the lithium secondary battery there are no particular restrictions on the shape of the lithium secondary battery.
  • any of a coin shape, a button shape, a sheet shape, a laminated shape, a cylindrical shape, a flat shape, a square shape, a large size used for an electric vehicle, etc. may be used.
  • the problem of battery swelling is likely to occur.
  • a lithium secondary battery pack having good characteristics can also be configured as a rectangular battery or a flat battery having an outer package.
  • the amount of power (Wh) of the secondary battery 1a constituting the secondary battery module that is, The ratio of the surface area (cm 2 ) of the outer package of the battery to the amount of energy that can be discharged from the secondary battery 1a in the charged state is preferably 7 cm 2 / Wh or more, and 8.5 cm 2 / Wh. More preferably, it is more preferably 10 cm 2 / Wh or more.
  • the ratio of the surface area of the outer package of the battery to the amount of power of the secondary battery 1a is 1000 cm 2 / Wh or less. Is preferably 100 cm 2 / Wh or less, and most preferably 50 cm 2 / Wh or less.
  • a Si-based active material especially SiOx
  • a wound electrode body particularly, a square battery, a flat outer can, a laminate film outer body
  • a lithium secondary battery pack having good characteristics can also be configured as a battery having a wound electrode body having a flat cross section perpendicular to the winding axis used in a flat battery using the above.
  • the lithium secondary battery pack of the present invention is a charging system of the present invention that can be rapidly charged by being mounted on a charging device having a configuration that has been widely used conventionally, such as a constant current constant voltage charging device or a pulse charging device.
  • a charging device having a configuration that has been widely used conventionally such as a constant current constant voltage charging device or a pulse charging device.
  • the charging method of the present invention capable of rapid charging can be implemented by such a charging system.
  • the lithium secondary battery pack of the present invention can ensure good rapid charging characteristics while increasing capacity, it has been known from the past, including power supplies for small and multifunctional portable devices, taking advantage of these characteristics. It can be suitably used for various applications to which the used lithium secondary battery pack is applied.
  • Example 1 [Production of positive electrode] LiCoO 2 as positive electrode active material: 80 parts by mass and LiMn 0.2 Ni 0.6 Co 0.2 O 2 : 20 parts by mass, artificial graphite as a conductive auxiliary agent: 1 part by mass and Ketjen black: 1 part by mass
  • 10 parts by mass of PVDF as a binder was mixed so as to be uniform using NMP as a solvent to prepare a positive electrode mixture-containing paste.
  • This positive electrode mixture-containing paste is intermittently applied to both surfaces of an aluminum foil (thickness 15 ⁇ m) while adjusting the thickness, dried, and then subjected to calendering, so that the thickness of the positive electrode mixture layer is adjusted to a total thickness of 120 ⁇ m.
  • the positive electrode was manufactured by cutting so as to have a width of 54.5 mm. Further, a tab was welded to the exposed portion of the aluminum foil of the positive electrode to form a lead portion.
  • a material in which the surface of SiO is coated with carbon (average particle diameter D 50 : 5 ⁇ m, hereinafter referred to as “SiO / carbon composite”) and graphitic carbon having an average particle diameter D 50 of 16 ⁇ m are 5:95.
  • a water-based negative electrode mixture-containing paste was prepared by mixing ion-exchanged water having a conductivity of 2.0 ⁇ 10 5 ⁇ / cm or more as a solvent.
  • the above-described material in which the surface of SiO is coated with carbon has a carbon coating amount of 20% by mass, the Raman spectrum I 510 / I 1343 intensity ratio at a measurement laser wavelength of 532 nm is 0.10, and CuK ⁇ rays are used.
  • the half width of the Si (111) diffraction peak in the X-ray diffraction measurement of SiO was 1.0 °.
  • the negative electrode mixture-containing paste described above is intermittently applied to both sides of a current collector made of copper foil with a thickness of 8 ⁇ m by adjusting the thickness, dried, and then subjected to a calendar treatment so that the total thickness becomes 108 ⁇ m.
  • the thickness of the mixture layer was adjusted, and the negative electrode was produced by cutting so that the width was 55.5 mm. Further, a tab was welded to the exposed portion of the copper foil of the negative electrode to form a lead portion.
  • the area of the negative electrode mixture layer is 599cm 2, Si amount of the negative electrode active material in per unit area was 0.14 mg / cm 2.
  • PE microporous separator for lithium secondary battery [Porous layer (A): Thickness 12 ⁇ m, porosity 40%, average pore diameter 0.08 ⁇ m, PE melting point 135 ° C.] corona discharge treatment (discharge amount 40 W) Min / m 2 ), and a porous layer (B) forming slurry is applied to the treated surface by a micro gravure coater and dried to form a porous layer (B) having a thickness of 4 ⁇ m. A separator was obtained. The mass per unit area of the porous layer (B) in this separator was 5.5 g / m 2 , the boehmite volume content was 95% by volume, and the porosity was 45%.
  • FIGS. 2A and 2B The positive electrode and negative electrode obtained as described above were overlapped with the separator porous layer (B) facing the positive electrode and wound in a spiral shape to produce a wound electrode body.
  • the obtained wound electrode body was crushed into a flat shape, placed in an aluminum outer can having a thickness of 5 mm, a width of 42 mm, and a height of 61 mm, and the nonaqueous electrolyte adjusted as described above was injected. Then, after injecting the non-aqueous electrolyte, the outer can was sealed to produce a lithium secondary battery having the structure shown in FIGS. 2A and 2B.
  • 2A is a partial cross-sectional view seen from the front
  • FIG. 2B is a plan view.
  • FIG. 3 is a perspective view showing the appearance of the lithium secondary battery.
  • the positive electrode 11 and the negative electrode 12 are spirally wound through the separator 13 as described above, and then pressed so as to be flattened to form a flat wound electrode body.
  • 14 is housed in a rectangular tube-shaped outer can 15 together with a non-aqueous electrolyte.
  • the wound electrode body 14 in FIG. 2 only the outer peripheral side portion is shown in cross section, and the inner peripheral side portion is not shown in cross section.
  • the metal foil, electrolyte solution, etc. as a collector used when producing the positive electrode 11 and the negative electrode 12 are not illustrated. Also, each layer of the separator is not shown separately.
  • the outer can 15 is made of an aluminum alloy and constitutes an outer casing of the battery, and also serves as a positive electrode terminal.
  • An insulator 16 made of a PE sheet is disposed at the bottom of the outer can 15. From the flat wound electrode body 14 composed of the positive electrode 11, the negative electrode 12 and the separator 13, a positive electrode lead body 17 and a negative electrode lead body 18 connected to one end of each of the positive electrode 11 and the negative electrode 12 are drawn out.
  • a stainless steel terminal 21 is attached to a sealing lid plate 19 made of aluminum alloy that seals the opening of the outer can 15 via a PP insulating packing 20, and an insulator 22 is attached to the terminal 21.
  • a stainless steel lead plate 23 is attached via
  • the cover plate 19 is inserted into the opening of the outer can 15 and welded to join the opening of the outer can 15 to seal the inside of the battery.
  • the lid plate 19 is provided with a non-aqueous electrolyte inlet 24.
  • a sealing member is inserted into the non-aqueous electrolyte inlet 24, and in that state, the battery is sealed by, for example, laser welding to ensure the sealing performance of the battery. Therefore, in this battery, the non-aqueous electrolyte inlet 24 actually corresponds to the non-aqueous electrolyte inlet and the sealing member, but is shown as the non-aqueous electrolyte inlet 24 for ease of explanation.
  • the lid plate 19 is provided with a cleavage vent 25 as a mechanism for discharging the internal gas to the outside when the battery temperature rises.
  • the outer can 15 and the lid plate 19 function as a positive electrode terminal by directly welding the positive electrode lead body 17 to the lid plate 19. Further, the negative electrode lead body 18 is welded to the lead plate 23, and the negative electrode lead body 18 and the terminal 21 are conducted through the lead plate 23, whereby the terminal 21 functions as a negative electrode terminal.
  • the sign may be reversed depending on the material of the outer can 15, the sign may be reversed.
  • FIG. 3 is shown for the purpose of showing that the lithium secondary battery shown in FIGS. 2A and 2B is a square battery. Therefore, FIG. 3 schematically shows the battery, and only specific members among the members constituting the battery are shown.
  • the lithium secondary battery has an impedance of 0.033 ⁇ , a capacity per electrode facing area of 2.8 mAh / cm 2 , and a ratio of the surface area of the outer package to the amount of power of the battery is 10.7 cm 2. / Wh.
  • Example 2 A lithium secondary battery was produced in the same manner as in Example 1 except that a Si alloy was used as the negative electrode active material instead of the SiO / carbon composite. A lithium secondary battery pack was produced in the same manner as in Example 1 except that this lithium secondary battery was used.
  • Example 3 The amount of Si in the negative electrode active material per unit area in the negative electrode was set to 0.02 mg / cm 2, and the amount of the negative electrode capacity decreased thereby was almost the same as that of the negative electrode manufactured in Example 1 with the negative electrode mixture layer thickened.
  • a negative electrode was produced in the same manner as in Example 1 except that the negative electrode capacity was changed to.
  • a lithium secondary battery was produced in the same manner as in Example 1 except that this negative electrode was used and the size of the outer can was changed in accordance with the thickness change of the negative electrode. And the lithium secondary battery pack was produced like Example 1 except having used this lithium secondary battery.
  • Example 4 The amount of Si in the negative electrode active material per unit area in the negative electrode was set to 0.18 mg / cm 2, and the amount of increase in the negative electrode capacity was thereby almost the same as that of the negative electrode produced in Example 1 with the negative electrode mixture layer being thinned.
  • a negative electrode was produced in the same manner as in Example 1 except that the negative electrode capacity was changed to.
  • a lithium secondary battery was produced in the same manner as in Example 1 except that this negative electrode was used.
  • the lithium secondary battery pack was produced like Example 1 except having used this lithium secondary battery.
  • Example 5 The capacity per electrode facing area was 3.3 mAh / cm 2, and the increased capacity was adjusted to the same capacity as the lithium secondary battery produced in Example 1 by adjusting the area of the positive and negative electrode mixture layers.
  • Example 6 In place of the electrolyte solution of Example 1, EC, MEC and DEC were mixed at a volume ratio of 1: 0.5: 1.5, and LiPF 6 was dissolved as a lithium salt at a concentration of 1.1 mol / l. Furthermore, VC, FEC and EDPA [Ethyl Diethylphosphonoacetate], LiPF 2 (C 2 O 4 ) 2 are 2.5% by mass, 1.75% by mass and 1.00% by mass, respectively. A non-aqueous electrolyte was prepared by adding 0.3% by mass. A lithium secondary battery pack was produced in the same manner as in Example 1 except that this non-aqueous electrolyte was used.
  • Example 7 A lithium secondary battery pack was produced in the same manner as in Example 6 except that LiBF 2 (C 2 O 4 ) was added in an amount of 0.3% by mass in place of the electrolytic solution of Example 6.
  • Example 8 A lithium secondary battery pack was produced in the same manner as in Example 1 except that C 6 H 4 (COOLi) 2 was added to the negative electrode paint in an amount of 0.3% by mass in terms of electrolyte solution to produce an electrode.
  • Example 1 The negative electrode active material was changed from a mixture of SiO / carbon composite and graphitic carbon to only graphitic carbon, and the negative electrode capacity was reduced by this, and the negative electrode mixture layer was thickened to produce in Example 1.
  • a negative electrode was produced in the same manner as in Example 5 except that the capacity was almost the same as that of the negative electrode.
  • a lithium secondary battery was produced in the same manner as in Example 1 except that this negative electrode was used and the size of the outer can was changed in accordance with the thickness change of the negative electrode. And the lithium secondary battery pack was produced like Example 1 except having used this lithium secondary battery.
  • Example 2 Example 1 except that the same lithium secondary battery as that manufactured in Comparative Example 1, a protection circuit including one FET having a resistance value of 0.05 ⁇ , and a PTC element having a resistance value of 0.03 ⁇ were used. Similarly, a lithium secondary battery pack was produced.
  • Example 3 Fabricated in Example 1 by changing the negative electrode active material from the mixture of SiO / carbon composite and graphitic carbon to only graphitic carbon, thereby increasing the electrode facing area by reducing the negative electrode capacity.
  • a lithium secondary battery was fabricated in the same manner as in Example 1 except that the capacity was adjusted to be the same as that of the lithium secondary battery. Further, a lithium secondary battery pack was produced in the same manner as in Comparative Example 2 except that this lithium secondary battery was used.
  • Comparative Example 4 The capacity per electrode facing area was 3.3 mAh / cm 2, and the increased capacity was adjusted to the same capacity as the non-aqueous secondary battery produced in Comparative Example 2 by adjusting the area of the positive and negative electrode mixture layers. Except for the above, a non-aqueous secondary battery and a non-aqueous secondary battery pack were produced in the same manner as in Comparative Example 2.
  • Example 5 A lithium secondary battery was produced in the same manner as in Example 6 except that the negative electrode produced in Comparative Example 1 was used and the size of the outer can was changed in accordance with the change in the thickness of the negative electrode. And the lithium secondary battery pack was produced like Example 1 except having used this lithium secondary battery.
  • a charging system was configured by combining the lithium secondary battery packs of Examples 1 to 8 and Comparative Examples 1 to 5 and a charge / discharge device, and a rapid charge test was performed by the following charging method.
  • the configuration of the lithium secondary battery and the slope at 40% SOC of the voltage-SOC curve obtained when charged at a current value of 1.5 C (Table 1) Shown in In addition, Table 2 shows the impedance, capacity, impedance capacity index, and evaluation results of the lithium secondary battery pack.
  • “voltage slope at 40% SOC” means the slope at 40% SOC of the voltage-SOC curve obtained when charging at a current value of 1.5C.
  • lithium secondary batteries of Examples 1 to 8 using a lithium secondary battery having a negative electrode containing a Si-based active material as a negative electrode active material and having an appropriate impedance capacity index Compared to the lithium secondary battery packs of Comparative Examples 1 to 4, the pack has a longer CC charge time during the quick charge test and a shorter time required for charging to SOC 90%. Further, from the comparison between the lithium secondary battery packs of the examples, the capacity per electrode facing area of the lithium secondary battery, the content of Si in the Si active material per unit area of the negative electrode mixture layer, SOC 40% It can also be seen that the quick charge characteristics of the lithium secondary battery pack can be further improved by adjusting the voltage slope at 1 to a more appropriate value.
  • the lithium secondary battery packs of Examples 6 to 8 using lithium secondary batteries in which a fluorine-containing organic metal salt having an oxalic acid group or a polyvalent organic metal salt is contained in a non-aqueous electrolyte are used in Examples.
  • the CC charge time during the quick charge test is longer, the time required for charging up to SOC 90% is further shortened, and the excellent effect of the additive can be confirmed. it can.
  • the difference in charging time between the lithium secondary battery packs of Comparative Example 1 and Comparative Example 5 is small, and in the case of a lithium secondary battery including a negative electrode using only graphitic carbon as a negative electrode active material, the effect of the additive is It can be seen that this is lower than that of a lithium secondary battery having a negative electrode containing a Si-based active material in the negative electrode active material.
  • the lithium secondary battery pack takes a long time to reach SOC 90% in a low temperature environment (for example, 5 ° C.).
  • the lithium secondary battery pack of the example is heated to room temperature (25 By charging while heating up to [° C.], it was possible to achieve a charging time substantially equivalent to that when charging in a room temperature environment. Therefore, it was found that the lithium secondary battery pack of the present invention can be rapidly charged by heating the pack itself even in a low temperature environment, and can be rapidly charged even in a wide temperature range.
  • Example 9 Except for adjusting the application position of the positive electrode and negative electrode mixture-containing paste so that the facing area between the positive electrode mixture layer and the negative electrode mixture layer is the same as in Example 1 during winding, the same as in Example 1.
  • the positive electrode and the negative electrode prepared in this manner were overlapped with the separator porous layer (B) facing the positive electrode, and were wound in a spiral shape so that the cross-section was substantially circular, thereby preparing a wound electrode body. .
  • the obtained wound electrode body was put into a cylindrical outer can, and a cylindrical lithium secondary battery having a diameter of 18 mm and a height of 65 mm was produced in the same manner as in Example 1.
  • the impedance is 0.032 ⁇
  • the capacity per electrode facing area of the battery is 2.8 mAh / cm 2
  • the ratio of the surface area of the outer package to the electric energy of the battery is 7 0.3 cm 2 / Wh.
  • a lithium secondary battery pack was obtained in the same manner as in Example 1. Assembled. About the obtained lithium secondary battery pack, the protection element part impedance calculated
  • the lithium secondary battery pack of Example 1 and the lithium secondary battery pack of Example 9 were each charged at a current value of 2C for 20 minutes in an environment of 25 ° C., and the surface temperature of the secondary battery at the end of charging. was measured.
  • the lithium secondary battery pack of Example 1 is rapidly charged at 1.5C, and the voltage applied to the lithium secondary battery pack is 4 This corresponds to 95% of the amount of electricity that can be charged until 2V is reached (28 minutes after the start of charging).
  • the surface temperature of the secondary battery constituting the lithium secondary battery pack of Example 1 is 27 ° C.
  • the surface temperature of the secondary battery constituting the lithium secondary battery pack of Example 9 is 38 ° C. I understood it.
  • the ratio of the surface area of the outer casing of the battery to the amount of rechargeable energy of the secondary battery in a fully charged state is 7 cm 2 / Wh or more, and the temperature of the battery due to rapid charging Although the rise was suppressed, the battery of Example 1 in which the ratio was 8.5 cm 2 / Wh or more was more suitable for rapid charging because the temperature rise was further suppressed.
  • Example 10 A lithium secondary battery pack was assembled in the same manner as in Example 1 except that two lithium secondary batteries produced in Example 1 were connected in series to form a secondary battery module.
  • required by the above-mentioned method is 0.018 (ohm)
  • capacitance of a lithium secondary battery module is 1.55Ah
  • a protection element impedance capacity index is 0.012. there were.
  • a charging system was configured by combining the lithium secondary battery pack of Example 10 and a charging / discharging device, and a rapid charging test was performed by the following charging method.
  • the voltage loss in the protection element section is distributed to each unit cell, so each unit when switching to CV charging
  • the voltage applied to the cell is higher than in the case of Example 1 in which the secondary battery module is configured by only one unit cell, and the time required for charging can be shortened.
  • the lithium secondary battery pack of the present invention is suitable as a power source for various uses including a power source for a small and multifunctional portable device because it has a high capacity and can secure a good quick charge characteristic.

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Abstract

Le bloc accumulateur au lithium selon l'invention comprend : un module (1) équipé d'un accumulateur au lithium (1a) ; et un circuit de protection (3) comprenant des FET (4a, 4b) permettant de réguler le courant de charge/décharge de l'accumulateur au lithium. Dans l'accumulateur au lithium, une partie d'élément de protection incluant les FET (4a, 4b) et similaire est disposée dans un chemin de charge/décharge. La partie d'élément de protection peut inclure un élément PTC (2). Une électrode négative contient un matériau actif en série au Si comme matériau actif négatif. Un seul accumulateur au lithium ou des accumulateurs au lithium connectés en parallèle constituent une cellule unitaire, et une seule cellule unitaire ou une pluralité de cellules unitaires connectées en série constituent une partie en série d'unités minimale (B1, B2). Le module est constitué d'une seule partie en série d'unités minimale ou d'une pluralité de parties en série d'unités minimales connectées en parallèle. Quand une impédance de partie d'élément de protection (PR) (Ω) est définie comme le produit entre la somme des impédances des éléments de protection respectifs et le nombre de parties en série d'unités minimales et la capacité de la partie en série d'unités minimale est appelée Q, un indice impédance d'élément de protection/capacité représenté par le ratio PR/Q est inférieur ou égal à 0,03. Les caractéristiques de charge rapide sont améliorées.
PCT/JP2013/056254 2012-03-07 2013-03-07 Bloc accumulateur au lithium, et dispositif électronique, système de charge, et procédé de charge l'utilisant Ceased WO2013133361A1 (fr)

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