WO2023184294A1 - 正极极片、二次电池、电池模块、电池包和用电装置 - Google Patents

正极极片、二次电池、电池模块、电池包和用电装置 Download PDF

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WO2023184294A1
WO2023184294A1 PCT/CN2022/084258 CN2022084258W WO2023184294A1 WO 2023184294 A1 WO2023184294 A1 WO 2023184294A1 CN 2022084258 W CN2022084258 W CN 2022084258W WO 2023184294 A1 WO2023184294 A1 WO 2023184294A1
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positive electrode
active material
range
cathode active
preparation example
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French (fr)
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季成
李白清
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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Priority to PCT/CN2022/084258 priority Critical patent/WO2023184294A1/zh
Priority to CN202280039978.1A priority patent/CN117425982A/zh
Priority to EP22919273.7A priority patent/EP4280310A4/en
Priority to US18/350,756 priority patent/US20230352667A1/en
Publication of WO2023184294A1 publication Critical patent/WO2023184294A1/zh
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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
    • 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
    • H01M4/364—Composites as mixtures
    • 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
    • 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
    • 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
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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

Definitions

  • the present application relates to the technical field of secondary batteries, and in particular, to a positive electrode plate, a secondary battery, a battery module, a battery pack and an electrical device.
  • secondary batteries are widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, Military equipment, aerospace and other fields. Due to the great development of secondary batteries, higher requirements have been put forward for their energy density, cycle performance and safety performance.
  • the existing lithium iron manganese phosphate makes the secondary battery have poor dynamic performance and low cell rate performance, which cannot meet the needs of power batteries.
  • the existing secondary batteries made of lithium iron phosphate as the cathode active material have excellent cycle stability and safety, but the existence of one-dimensional lithium ion channels inside them and the existence of two phases of LiFePO 4 and FePO 4 during the charge and discharge process
  • the internal phase change resistance of the material increases during the charge and discharge process, resulting in poor dynamic performance of the secondary battery, low cell rate performance, short low-temperature cycle life, and low low-temperature capacity retention rate.
  • This application was made in view of the above-mentioned issues, and its purpose is to provide a cathode plate, a secondary battery, a battery module, a battery pack and a power device to solve the energy problem of secondary batteries made with existing cathode active materials. Problems include low density, poor kinetic performance, low rate performance, short low-temperature cycle life, and low low-temperature cycle capacity retention rate.
  • the first aspect of the present application provides a positive electrode sheet, including a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector; the positive electrode film layer has a single-layer structure or a multi-layer structure. ;
  • the positive electrode film layer has a single-layer structure, at least one positive electrode film layer simultaneously contains the first positive electrode active material with the chemical formula Li a A x Mn 1-y R y P 1-z C z O 4-n D n and the third positive electrode active material.
  • At least one layer of the at least one positive electrode film layer also contains a chemical formula of Li a A x Mn 1-y R y P 1-z C z O 4-n D n first positive electrode active material and second positive electrode active material; wherein, A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; R includes One or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge; C includes one or more elements selected from B, S, Si and N or Multiple elements; D includes one or more elements selected from S, F, Cl and Br; a is selected from the range of 0.9 to 1.1, x is selected from the range of 0.001 to 0.1, and y is selected from the range of 0.001 to 0.5 , z is selected from the range of 0.001 to 0.1, n is selected from the range of 0.001
  • the applicant unexpectedly discovered that by doping the Li site, Mn site, P site and O site of the compound LiMnPO 4 with specific elements simultaneously in specific amounts to obtain the first cathode active material, significantly improved rate performance can be obtained , while significantly reducing the dissolution of Mn and Mn-site doping elements, achieving significantly improved cycle performance and/or high temperature stability, and the gram capacity and compaction density of the material are also improved, and interface side reactions are reduced.
  • the first positive electrode active material and the second positive electrode active material are mixed and used.
  • the advantages of the two materials complement each other, which improves the energy density of the secondary battery.
  • the secondary battery has excellent kinetic performance, rate performance, Low temperature cycle life and low temperature cycle capacity retention.
  • a second aspect of the application also provides a positive electrode sheet, including a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector; at least one positive electrode film layer has a multi-layer structure, and any one has a multi-layer structure.
  • the cathode film layer contains a first cathode active material and a second cathode active material with the chemical formula Li a A x Mn 1-y R y P 1-z C z O 4-n D n in different layers; where, A Including one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; R includes selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb , Nb and Ge; C includes one or more elements selected from B, S, Si and N; D includes one or more elements selected from S, F, Cl and Br elements; a is selected from the range of 0.9 to 1.1, x is selected from the range of 0.001 to 0.1, y is selected from the range of 0.001 to 0.5, z is selected from the range of 0.001 to 0.1, n is selected from the range of 0.001 to 0.1; second The positive active material is one or more selected from the group consisting of LiFePO 4 ,
  • the first cathode active material has significantly improved rate performance, while significantly reducing the dissolution of Mn and Mn-site doping elements, obtaining significantly improved cycle performance and/or high temperature stability, and the gram capacity and compacted density of the material are improved. It is also improved and interface side reactions are reduced.
  • This application combines the first positive electrode active material and the second positive electrode active material.
  • the advantages of the two materials complement each other, which improves the energy density of the secondary battery.
  • the secondary battery has excellent rate performance, dynamic performance, and low temperature. Cycle life and low temperature cycle capacity retention.
  • a third aspect of the present application provides a positive electrode sheet, including a positive current collector and positive electrode film layer A and positive electrode film layer B respectively disposed on two surfaces of the positive electrode current collector; positive electrode film layer A and positive electrode film layer B are independent
  • the ground has a single-layer structure or a multi-layer structure; at least one layer of the cathode film layer A contains the first cathode active material with the chemical formula Li a A x Mn 1-y R y P 1-z C z O 4-n D n , at the same time, at least one layer of the cathode film layer B contains a second cathode active material; wherein A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; R Including one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge; C includes one selected from B, S, Si and N Or multiple elements; D includes one or more elements selected from S, F,
  • the first cathode active material has significantly improved rate performance, while significantly reducing the dissolution of Mn and Mn-site doping elements, obtaining significantly improved cycle performance and/or high temperature stability, and the gram capacity and compacted density of the material are improved. It is also improved and interface side reactions are reduced.
  • This application combines the first positive electrode active material and the second positive electrode active material.
  • the advantages of the two materials complement each other, which improves the energy density of the secondary battery.
  • the secondary battery has excellent rate performance, dynamic performance, and low temperature. Cycle life and low temperature cycle capacity retention.
  • the above limitation on the numerical range of The limitation of the stoichiometric number of each element as A is also the limitation of the sum of the stoichiometric numbers of each element as A.
  • the respective stoichiometric numbers x1, x2...xn of A1, A2...An must fall within the numerical range of x defined in this application, and x1
  • the sum of , x2...xn also needs to fall within this numerical range.
  • R, C and D are two or more elements
  • the limitations on the numerical ranges of the stoichiometric numbers of R, C and D in this application also have the above meaning.
  • the above-mentioned limitation on the numerical range of c is not only a limitation on the stoichiometric number of each element as M, but also on each As a definition of the sum of the stoichiometric numbers of the elements of M.
  • M is two or more elements M1, M2...Mn
  • the stoichiometric numbers c1, c2...cn of M1, M2...Mn must fall within the numerical range of c defined in this application, and c1
  • the sum of , c2...cn also needs to fall within this numerical range.
  • the carbon mass accounts for 0.1%-4% of the mass of the carbon-coated LiFePO4 ; and/or the carbon mass accounts for 0.1%-4% of the mass of the carbon-coated LiFePO4 ; 0.1%-4% of the mass of McPO 4 .
  • Using the second positive electrode active material with the above-mentioned carbon mass content can further ensure that the secondary battery has excellent rate performance, kinetic performance and low-temperature cycle performance, and has a high energy density.
  • the mass ratio of the first cathode active material to the second cathode active material is 1:7-7:1, optionally 1:4-4:1.
  • R is selected from at least one of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge. Two elements. Thereby, the composition of the first positive electrode active material can be controlled more accurately.
  • A is any element selected from Mg and Nb; and/or, R is selected from Fe, Ti, V, Co and at least two elements in Mg, optionally Fe and one or more elements selected from Ti, V, Co and Mg; and/or, C is S; and/or, D is F.
  • x is selected from the range of 0.001-0.005. By selecting the value of x within this range, the dynamic performance of the first positive electrode active material can be further improved.
  • y is selected from the range of 0.01 to 0.5, optionally selected from the range of 0.25 to 0.5. By selecting the y value within this range, the gram capacity and rate performance of the first cathode active material can be further improved.
  • z is selected from the range of 0.001 to 0.005. By selecting the z value within this range, the rate performance of the secondary battery can be further improved.
  • n is selected from the range of 0.001 to 0.005. By selecting the n value within this range, the high-temperature performance of the secondary battery can be further improved.
  • the ratio of (1-y) to y is selected from 1-4, optionally selected from 1.5-3. This can further improve the energy density and cycle performance of secondary batteries.
  • the ratio of a to x is selected from 9-1100, optionally selected from 190-998.
  • the energy density and cycle performance of the secondary battery can be further improved.
  • the lattice change rate of the first cathode active material is 8% or less, optionally 4% or less. By reducing the lattice change rate, it is beneficial to improve the rate performance of secondary batteries.
  • the lattice change rate can be measured by methods known in the art, such as X-ray diffraction (XRD).
  • the Li/Mn antisite defect concentration of the first cathode active material is 2% or less, optionally 0.5% or less.
  • the so-called Li/Mn antisite defect refers to the interchange of positions between Li + and Mn 2+ in the LiMnPO 4 lattice.
  • the Li/Mn anti-site defect concentration refers to the percentage of Li + exchanged with Mn 2+ in the positive active material to the total amount of Li + .
  • the Li/Mn anti-site defect concentration can be measured by methods known in the art, such as XRD.
  • the surface oxygen valence state of the first cathode active material is -1.82 or less, optionally -1.89 to -1.98.
  • the interface side reaction between the first positive electrode active material and the electrolyte can be reduced, thereby improving the cycle performance and high temperature stability of the secondary battery.
  • Surface oxygen valence state can be measured by methods known in the art, such as by electron energy loss spectroscopy (EELS).
  • the first cathode active material has a compacted density at 3T of 2.0 g/cm 3 or more, optionally 2.2 g/cm 3 or more.
  • the higher the compaction density the greater the weight of the first positive active material per unit volume. Therefore, increasing the compaction density is beneficial to increasing the volumetric energy density of the battery core.
  • the compacted density can be measured according to GB/T24533-2009.
  • the surface of the first cathode active material is further coated with carbon. Thereby, the conductivity of the first positive electrode active material can be improved.
  • the sum of the mass of the first cathode active material and the second cathode active material accounts for 88%-98.7% of the mass of the cathode plate. This further ensures that the secondary battery has excellent rate performance, kinetic performance and low-temperature cycle performance, as well as high energy density.
  • a fourth aspect of the present application provides a secondary battery, including the positive electrode plate of any one of the first to third aspects of the present application.
  • a fifth aspect of the present application provides a battery module including the secondary battery of the fourth aspect of the present application.
  • a sixth aspect of the present application provides a battery pack, including the battery module of the fifth aspect of the present application.
  • a seventh aspect of the present application provides an electrical device, including at least one selected from the group consisting of the secondary battery of the fourth aspect of the present application, the battery module of the fifth aspect of the present application, and the battery pack of the sixth aspect of the present application. kind.
  • FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .
  • FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 4 .
  • FIG. 6 is a schematic diagram of a power consumption device using a secondary battery as a power source according to an embodiment of the present application.
  • FIG. 7 is a schematic diagram of the battery structure made of the positive electrode plate P1 of the present application.
  • FIG 8 is a schematic diagram of the battery structure made of the positive electrode plate P2 of the present application.
  • FIG. 9 is a schematic diagram of the battery structure made of the positive electrode plate P3 of the present application.
  • FIG 10 is a schematic diagram of the battery structure made of the positive electrode plate P8 of the present application.
  • FIG 11 is a schematic diagram of the battery structure made of the positive electrode plate P10 of the present application.
  • Figure 12 is a schematic diagram of the battery structure made of the positive electrode plate P11 of the present application.
  • Figure 13 is a schematic diagram of the battery structure made of the positive electrode plate P12 of the present application.
  • Figure 14 is a schematic diagram of the battery structure made of the positive electrode plate P17 of the present application.
  • Figure 15 is a schematic diagram of the battery structure made of the positive electrode plate P18 of the present application.
  • Figure 16 is a schematic diagram of the battery structure made of the positive electrode plate P23 of the present application.
  • FIG 17 is a schematic diagram of the battery structure made of the positive electrode plate P24 of the present application.
  • Figure 18 is a schematic diagram of the battery structure made of the positive electrode plate P26 of the present application.
  • Figure 19 is a schematic diagram of the battery structure made of the positive electrode plate P27 of the present application.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • a method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) can be added to the method in any order.
  • the method may include steps (a), (b) and (c), and may also include step (a). , (c) and (b), and may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • Secondary batteries also known as rechargeable batteries or storage batteries, refer to batteries that can be recharged to activate active materials and continue to be used after the battery is discharged.
  • a secondary battery normally includes a positive electrode plate, a negative electrode plate, a separator and an electrolyte.
  • active ions such as lithium ions
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows active ions to pass through.
  • the electrolyte is between the positive electrode piece and the negative electrode piece and mainly plays the role of conducting active ions.
  • An embodiment of the first aspect of the present application provides a positive electrode sheet, including a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector; the positive electrode film layer has a single-layer structure or a multi-layer structure; when the positive electrode When the film layer has a single-layer structure, at least one cathode film layer simultaneously contains the first cathode active material and the second cathode active material with the chemical formula Li a A x Mn 1-y R y P 1-z C z O 4-n D n material; and/or, when the positive electrode film layer has a multi-layer structure, at least one layer of the at least one positive electrode film layer also contains a chemical formula of Li a A x Mn 1-y R y P 1-z C z O 4-n
  • the first cathode active material and the second cathode active material of Dn wherein A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; R includes one
  • n is selected from the range of 0.001 to 0.1; the second positive electrode active material is selected from LiFePO 4 , carbon-coated LiFePO 4 , LiFe b M c PO 4 and carbon-coated LiFe b M c PO 4
  • M independently includes one selected from Ti, Zn, Co, Mn, La, V, Mg, Al, Nb, W, Zr, Nb, Sm, Cr, Cu and B or multiple elements
  • the positive electrode film layer has a single-layer structure or a multi-layer structure
  • the two positive electrode film layers independently have a single-layer structure or a multi-layer structure
  • “when "When the positive electrode film layer is a single-layer structure” refers to when one or two positive electrode film layers are a single-layer structure
  • “when the positive electrode film layer is a multi-layer structure” refers to when one or two positive electrode film layers are a multi-layer structure.
  • the first cathode active material of the present application is obtained by element doping in the compound LiMnPO 4 , where A, R, C and D are respectively doped at the Li site, Mn site, P site and O site of the compound LiMnPO 4 Elements.
  • the performance improvement of lithium manganese phosphate is related to reducing the lattice change rate of lithium manganese phosphate and reducing surface activity during the process of deintercalating lithium. Reducing the lattice change rate can reduce the lattice constant difference between the two phases at the grain boundary, reduce the interface stress, and enhance the transport capability of Li + at the interface, thereby improving the rate performance of the cathode active material.
  • the lattice change rate is reduced by Li and Mn site doping.
  • Mn site doping also effectively reduces surface activity, thereby inhibiting Mn dissolution and interface side reactions between the cathode active material and the electrolyte.
  • P-site doping makes the Mn-O bond length change faster and reduces the material's small polaron migration barrier, thereby benefiting the electronic conductivity.
  • O-site doping has a good effect on reducing interface side reactions. The doping of P-site and O-site also affects the Mn dissolution and kinetic properties of anti-site defects.
  • doping reduces the concentration of anti-site defects in the material, improves the dynamic properties and gram capacity of the material, and can also change the morphology of the particles, thereby increasing the compaction density.
  • the applicant unexpectedly discovered that by simultaneously doping specific elements in specific amounts at the Li site, Mn site, P site and O site of the compound LiMnPO 4 , significantly improved rate performance can be obtained while significantly reducing the number of Mn and Mn sites. By dissolving the doping elements, significantly improved cycle performance and/or high-temperature stability are obtained, and the gram capacity and compacted density of the material can also be increased.
  • the advantages of the two materials complement each other and improve the energy density of the secondary battery;
  • the first positive electrode active material is evenly dispersed around the second positive electrode active material , the doping of Li sites, P sites, and Mn sites of the first cathode active material can further reduce the lattice change rate during the delithiation process and increase the electronic conductivity, thereby overall improving the conductivity and delithiation of the mixed materials.
  • the lithium insertion rate improves the energy density of secondary batteries and enables the mixed materials to have excellent power performance and low temperature performance.
  • the interface side reactions are reduced, resulting in good cycle stability without deteriorating cycle performance.
  • the stable skeleton structure of the second material in the mixed material is conducive to improving the stability of the first cathode material, so that the secondary battery has excellent cycle performance.
  • a positive electrode film layer C and a positive electrode film layer D are respectively provided on both surfaces of the positive electrode current collector.
  • the positive electrode film layer C has a multi-layer structure
  • the positive electrode film layer D has a single-layer structure.
  • at least one of the cathode film layers C contains both the first cathode active material and the second cathode active material; optionally, the cathode film layer D contains one or both of the first cathode active material and the second cathode active material. kind; optionally, the remaining layers in the positive electrode film layer C include the first positive electrode active material or the second positive electrode active material.
  • a positive electrode film layer C and a positive electrode film layer D are respectively provided on both surfaces of the positive electrode current collector.
  • the positive electrode film layer C has a multi-layer structure
  • the positive electrode film layer D has a single-layer structure.
  • the cathode film layer D contains both the first cathode active material and the second cathode active material; optionally, any layer in the cathode film layer C contains the first cathode active material or the second cathode active material.
  • one positive electrode film layer is respectively provided on both surfaces of the positive electrode current collector, each positive electrode film layer has a multi-layer structure, and at least one layer of each positive electrode film layer is simultaneously A first cathode active material and a second cathode active material are included; optionally, the remaining layers in the cathode film layer include the first cathode active material or the second cathode active material.
  • An embodiment of the second aspect of the present application provides a positive electrode sheet, including a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector; at least one positive electrode film layer has a multi-layer structure, any one having multiple
  • the cathode film layer of the layer structure respectively contains a first cathode active material and a second cathode active material with the chemical formula Li a A x Mn 1-y R y P 1-z C z O 4-n D n in different layers; wherein , A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; R includes selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn , Sb, Nb and Ge; C includes one or more elements selected from B, S, Si and N; D includes one or more elements selected from S, F, Cl and Br or multiple elements; a is selected from the range of 0.9 to 1.1, x is selected from the range of
  • one positive electrode film layer is respectively provided on two surfaces of the positive electrode current collector, each positive electrode film layer has a multi-layer structure, and two adjacent layers in each positive electrode film layer A first positive electrode active material and a second positive electrode active material are respectively included.
  • a positive electrode film layer E and a positive electrode film layer F are respectively provided on both surfaces of the positive electrode current collector.
  • the positive electrode film layer E has a multi-layer structure
  • the positive electrode film layer F has a single-layer structure.
  • the two adjacent layers in the positive electrode film layer E respectively include the first positive electrode active material and the second positive electrode active material; optionally, the remaining layers in the positive electrode film layer E and the positive electrode film layer F include the first positive electrode active material or the second positive electrode active material.
  • An embodiment of the third aspect of the present application provides a positive electrode sheet, including a positive electrode current collector and positive electrode film layer A and positive electrode film layer B respectively disposed on two surfaces of the positive electrode current collector; positive electrode film layer A and positive electrode film Layer B is independently a single-layer structure or a multi-layer structure; at least one layer of the positive electrode film layer A contains the first chemical formula of Li a A x Mn 1-y R y P 1-z C z O 4-n D n Positive electrode active material, at the same time, at least one layer of the positive electrode film layer B contains a second positive electrode active material; wherein A includes one or more selected from Zn, Al, Na, K, Mg, Nb, Mo and W Elements; R includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge; C includes one or more elements selected from B, S, Si and N One or more elements; D includes one or more elements selected from S, F, Cl and Br; a is
  • the first cathode active material has significantly improved rate performance, while significantly reducing the dissolution of Mn and Mn-site doping elements, and obtaining significantly improved cycle performance and/or high temperature.
  • the stability, gram capacity and compacted density of the material are also improved, and interface side reactions are reduced.
  • the specific principles are the same as in the first embodiment of the present application.
  • this application combines the first cathode active material and the second cathode active material.
  • the advantages of the two materials complement each other, which improves the energy density of the secondary battery and makes the secondary battery have both excellent properties. rate performance, kinetic performance, low-temperature cycle life and low-temperature cycle capacity retention rate.
  • the first cathode active material is evenly dispersed around the second cathode active material, and the doping of Li sites, P sites, and Mn sites of the first cathode active material can further reduce the lattice change rate during the delithiation process and Improving the electronic conductivity can overall improve the conductivity of the mixed materials and the lithium deintercalation rate, thereby increasing the energy density of the secondary battery and making the mixed materials have excellent power performance and low-temperature performance.
  • the doping of O sites in the first cathode material thanks to the doping of O sites in the first cathode material, the interface side reactions are reduced, resulting in good cycle stability without deteriorating cycle performance.
  • the stable skeleton structure of the second material in the mixed material is conducive to improving the stability of the first cathode material, so that the secondary battery has excellent cycle performance.
  • the above limitation on the numerical range of The limitation of the stoichiometric number of each element as A is also the limitation of the sum of the stoichiometric numbers of each element as A.
  • the respective stoichiometric numbers x1, x2...xn of A1, A2...An must fall within the numerical range of x defined in this application, and x1
  • the sum of , x2...xn also needs to fall within this numerical range.
  • R, C and D are two or more elements
  • the limitations on the numerical ranges of the stoichiometric numbers of R, C and D in this application also have the above meaning.
  • the above-mentioned limitation on the numerical range of c is not only a limitation on the stoichiometric number of each element as M, but also on each As a definition of the sum of the stoichiometric numbers of the elements of M.
  • M is two or more elements M1, M2...Mn
  • the stoichiometric numbers c1, c2...cn of M1, M2...Mn must fall within the numerical range of c defined in this application, and c1
  • the sum of , c2...cn also needs to fall within this numerical range.
  • the first cathode active material Li a x Mn 1-y R y P 1-z C z O 4-n D n remains electrically neutral throughout.
  • LiFebMcPO4 remains electrically neutral throughout.
  • the carbon mass accounts for 0.1%-4% of the mass of the carbon-coated LiFePO 4 ; and/or the carbon mass accounts for 0.1%-4% of the mass of the carbon-coated LiFe b 0.1%-4% of the mass of McPO 4 .
  • Using the second positive electrode active material with the above-mentioned carbon mass content can further ensure that the secondary battery has excellent rate performance, kinetic performance and low-temperature cycle performance, and has a high energy density.
  • the mass ratio of the first active material to the second active material is 1:7-7:1, optionally 1:4-4:1, further optionally 1:3-3:1, such as 1:7, 1:5, 1:3, 1:2, 3:5, 1:1, 5:3, 2:1, 3:1, 5:1, 7:1.
  • R is selected from the group consisting of Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb and Ge. At least two elements. Thereby, the composition of the first positive electrode active material can be controlled more easily and accurately.
  • A is any element selected from Mg and Nb; and/or, R is selected from Fe, Ti, V, At least two elements among Co and Mg are optionally Fe and one or more elements selected from Ti, V, Co and Mg; and/or, C is S; and/or, D is F.
  • the rate performance of the secondary battery can be further improved.
  • the side reactions at the interface can be further reduced and the high-temperature performance of the secondary battery can be improved.
  • x is selected from the range of 0.001-0.005. By selecting the value of x within this range, the dynamic performance of the first positive electrode active material can be further improved.
  • y is selected from the range of 0.01 to 0.5, optionally selected from the range of 0.25 to 0.5. By selecting the y value within this range, the gram capacity and rate performance of the first cathode active material can be further improved.
  • z is selected from the range of 0.001 to 0.005. By selecting the z value within this range, the rate performance of the secondary battery can be further improved.
  • n is selected from the range of 0.001 to 0.005. By selecting the n value within this range, the high-temperature performance of the secondary battery can be further improved.
  • the ratio of (1-y) to y is selected from 1-4, optionally selected from 1.5-3, and a and x The ratio is selected from 9-1100, optionally selected from 190-998. When this condition is met, the energy density and cycle performance of the secondary battery can be further improved.
  • the first cathode active material has a lattice change rate of 8% or less, optionally 4% or less.
  • a lattice change rate can be measured by methods known in the art, such as X-ray diffraction (XRD).
  • the Li/Mn antisite defect concentration of the first cathode active material is 2% or less, optionally 0.5% or less.
  • the so-called Li/Mn antisite defect refers to the interchange of positions between Li + and Mn 2+ in the LiMnPO 4 lattice.
  • the Li/Mn anti-site defect concentration refers to the percentage of Li + exchanged with Mn 2+ in the positive active material to the total amount of Li + .
  • the Li/Mn anti-site defect concentration can be measured by methods known in the art, such as XRD.
  • the surface oxygen valence state of the first cathode active material is -1.82 or less, optionally -1.89 to -1.98.
  • the interface side reaction between the first positive electrode active material and the electrolyte can be reduced, thereby improving the cycle performance and high temperature stability of the secondary battery.
  • Surface oxygen valence state can be measured by methods known in the art, such as by electron energy loss spectroscopy (EELS).
  • the first cathode active material has a compacted density at 3T of 2.0 g/cm or more, optionally 2.2 g/cm or more.
  • the higher the compaction density the greater the weight of the first positive active material per unit volume. Therefore, increasing the compaction density is beneficial to increasing the volumetric energy density of the battery core.
  • the compacted density can be measured according to GB/T24533-2009.
  • the surface of the first cathode active material is further coated with carbon. Thereby, the conductivity of the first positive electrode active material can be improved.
  • the sum of the masses of the first cathode active material and the second cathode active material accounts for 88% to 98.7% of the mass of the cathode plate. This further ensures that the secondary battery has excellent rate performance, kinetic performance and low-temperature cycle performance, as well as high energy density.
  • the positive electrode current collector has two surfaces opposite in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector. Those who come up.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode film layer may further include other positive electrode active materials known in the art for secondary batteries.
  • the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for secondary batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 , LiMn 2 O 4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide , at least one of lithium nickel manganese oxide and its modified compounds.
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium manganese phosphate (such as LiMnPO 4 ), composites of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and composite materials of lithium manganese iron phosphate and carbon. A sort of.
  • the positive electrode film layer optionally further includes a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene tripolymer. At least one of a meta-copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer and a fluorine-containing acrylate resin.
  • the positive electrode film layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the first cathode active material with the chemical formula Li a Ax Mn 1-y R y P 1-z C z O 4-n D n is prepared by the following steps :
  • Step (1) Mix a manganese source, a source of element R, an acid and an optional solvent to obtain a mixture;
  • Step (2) Mix the mixture with a lithium source, a phosphorus source, a source of element A, a source of element C, a source of element D and an optional solvent, dry and sinter to obtain Li a A x Mn 1-y R Core material of y P 1-z C z O 4-n D n .
  • a lithium source a phosphorus source
  • a source of element A a source of element A
  • a source of element C a source of element D and an optional solvent
  • dry and sinter dry and sinter to obtain Li a A x Mn 1-y R Core material of y P 1-z C z O 4-n D n .
  • step (1) is mixed at 60°C-120°C; and/or, in step (1), mixing is carried out by stirring at 200-800 rpm.
  • step (2) mixing is performed for 8-15 hours.
  • step (2) sintering is performed at 600°C to 900°C for 6 to 14 hours.
  • the source of element A is one or more selected from the group consisting of elements, oxides, phosphates, oxalates, carbonates and sulfates of element A. ;and / or,
  • the source of element R is one or more selected from elemental elements, oxides, phosphates, oxalates, carbonates and sulfates of element R; and/or,
  • the source of element C is one or more selected from sulfate, borate, nitrate and silicate of element C; and/or,
  • the source of element D is one or more selected from the group consisting of elemental elements and ammonium salts of element D.
  • the manganese source may be a manganese-containing material known in the art that can be used to prepare lithium manganese phosphate.
  • the manganese source may be one or more selected from the group consisting of elemental manganese, manganese dioxide, manganese phosphate, manganese oxalate, and manganese carbonate.
  • the acid may be one or more selected from organic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, silicic acid, silicic acid, etc., and organic acids such as oxalic acid.
  • the acid is a dilute organic acid with a concentration of 60% by weight or less.
  • the lithium source may be a lithium-containing substance known in the art that can be used to prepare lithium manganese phosphate.
  • the lithium source is one or more selected from lithium carbonate, lithium hydroxide, lithium phosphate, and lithium dihydrogen phosphate.
  • the phosphorus source may be a phosphorus-containing material known in the art that can be used to prepare lithium manganese phosphate.
  • the phosphorus source is one or more selected from diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate and phosphoric acid.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector.
  • the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for secondary batteries.
  • the negative active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the negative electrode film layer optionally further includes a binder.
  • the binder may be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), At least one of polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer optionally further includes a conductive agent.
  • the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode piece can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the type of electrolyte in this application can be selected according to needs.
  • the electrolyte can be liquid, gel, or completely solid.
  • the electrolyte is liquid and includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluoroborate, lithium dioxaloborate, lithium difluorodioxalate phosphate and lithium tetrafluoroxalate phosphate.
  • the solvent may be selected from the group consisting of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, Butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte optionally also includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • the secondary battery further includes a separator film.
  • a separator film There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the above-mentioned positive electrode sheet, negative electrode sheet and isolation film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 1 shows a square-structured secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.
  • FIG. 3 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space in which a plurality of secondary batteries 5 are received.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present application.
  • the secondary battery, battery module, or battery pack may be used as a power source for the power-consuming device, or as an energy storage unit for the power-consuming device.
  • Electric devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric Trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • secondary batteries, battery modules or battery packs can be selected according to its usage requirements.
  • FIG. 6 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • Preparation of doped manganese oxalate Mix 1.3mol MnSO 4 ⁇ H 2 O and 0.7mol FeSO 4 ⁇ H 2 O thoroughly in a mixer for 6 hours; transfer the mixture to the reaction kettle, add 10L deionized water and 2mol Dihydrate oxalic acid, heat to 80°C, and then stir at 600 rpm for 6 hours. The reaction is terminated (no bubbles are generated), and a suspension of Fe-doped manganese oxalate is obtained; filter the suspension, and dry the filter cake at 120°C and grind it. , obtaining Fe-doped manganese oxalate particles with a particle size Dv 50 of about 100nm;
  • Preparation of doped lithium manganese phosphate Take 1 mol of Fe-doped manganese oxalate particles, 0.497 mol of lithium carbonate, 0.001 mol of Mo(SO 4 ) 3 , an 85% phosphoric acid aqueous solution containing 0.999 mol of phosphoric acid, and 0.001 mol of H 4 SiO 4 , 0.0005 mol NH 4 HF 2 and 0.005 mol sucrose were added to 20L deionized water, and the mixture was transferred to a sand mill and thoroughly ground and stirred for 10 hours to obtain a slurry; the slurry was transferred to a spray drying equipment for spraying Dry and granulate, set the drying temperature to 250°C, and dry for 4 hours to obtain particles; in a nitrogen (90% v/v) + hydrogen (10% v/v) protective atmosphere, sinter the particles at 700°C for 10 hours , obtaining the cathode active material 1, carbon-coated Li 0.994 Mo 0.001 M
  • the cathode active material was prepared in the same manner as Preparation Example 1, but the stirring speed, temperature, grinding and stirring time in the sand mill, sintering temperature and sintering time when preparing doped manganese oxalate were changed, as shown in Table 1 below. .
  • the cathode active material was prepared in the same manner as Preparation Example 1, but the sources of lithium source, manganese source, phosphorus source and doping elements A, B, C, and D were changed, as shown in Table 2 below.
  • the composition of the prepared cathode active material is the same as that in Example 1, that is, Li 0.994 Mo 0.001 Mn 0.65 Fe 0.35 P 0.999 Si 0.001 O 3.999 F 0.001 .
  • Preparation of manganese oxalate add 1 mol of MnSO 4 . H 2 O was added to the reaction kettle, and 10 L of deionized water and 1 mol of oxalic acid dihydrate (calculated as oxalic acid) were added. The reaction kettle was heated to 80°C and stirred at 600 rpm for 6 hours. The reaction was terminated (no bubbles were generated), and a manganese oxalate suspension was obtained. The suspension is then filtered, and the filter cake is dried at 120° C. and then ground to obtain manganese oxalate particles with a median particle size Dv 50 of 50-200 nm.
  • Preparation of lithium manganese phosphate Take 1 mol of the above manganese oxalate particles, 0.5 mol of lithium carbonate, an 85% phosphoric acid aqueous solution containing 1 mol of phosphoric acid, and 0.005 mol of sucrose and add them to 20 L of deionized water. The mixture was transferred to a sand mill and thoroughly ground and stirred for 10 hours to obtain a slurry. Transfer the slurry to spray drying equipment for spray drying and granulation. Set the drying temperature to 250°C and dry for 4 hours to obtain granules. In a protective atmosphere of nitrogen (90 volume %) + hydrogen (10 volume %), the above powder was sintered at 700° C. for 10 hours to obtain carbon-coated LiMnPO 4 .
  • the positive active material, binder PVDF and conductive agent superconducting carbon black (Super-P) are mixed at a mass ratio of 97%:1.5%:1.5%, and then dispersed in N-methylpyrrolidone solvent to obtain a solid content of 60% w/w slurry of positive active material.
  • the slurry of the positive electrode active material in Preparation Example 1 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode.
  • the slurry of the positive electrode active material in Preparation Example 55 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode.
  • Film P2 The slurry of the positive electrode active material in Preparation Example 55 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode. Film P2.
  • the slurry of the cathode active material in Preparation Example 1 was evenly coated on one side of the aluminum foil in a coating amount of 0.019g/cm 2
  • the slurry of the cathode active material in Preparation Example 55 was evenly coated in a coating amount of 0.019g/cm 2 Coat it on the other side of the aluminum foil, vacuum dry it at a high temperature of 100-120°C for 14 hours, and compact it with a roller press to obtain the positive electrode piece P3.
  • the slurry of the positive electrode active material in Preparation Example 56 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as Example 3 to obtain the positive electrode sheet P4.
  • the slurry of the cathode active material in Preparation Example 1 was evenly coated on one side of the aluminum foil in a coating amount of 0.019g/cm 2
  • the slurry of the cathode active material in Preparation Example 56 was evenly coated in a coating amount of 0.019g/cm 2 Coating on the other side of the aluminum foil, the rest is the same as in Example 3 to obtain the positive electrode sheet P5.
  • the slurry of the cathode active material in Preparation Example 55 was evenly coated on one side of the aluminum foil in a coating amount of 0.019g/ cm2
  • the slurry of the cathode active material in Preparation Example 56 was evenly coated in a coating amount of 0.019g/ cm2 .
  • Coating on the other side of the aluminum foil, the rest is the same as in Example 3 to obtain the positive electrode piece P6.
  • the slurry of the cathode active material in Preparation Example 1 and the slurry of the cathode active material in Preparation Example 55 were sequentially coated on both sides of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 , and then, at 100 to 120 °C high temperature vacuum drying for 14 hours, and compacted by a roller press to obtain the positive electrode piece P7.
  • the slurry of the cathode active material in Preparation Example 55 and the slurry of the cathode active material in Preparation Example 1 were sequentially coated on both sides of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 , and the others were the same as in Example 7. , obtain the positive electrode piece P8.
  • the slurry of the cathode active material in Preparation Example 1 and the slurry of the cathode active material in Preparation Example 56 were sequentially coated on both sides of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 , and the others were the same as in Example 7. , to obtain the positive electrode piece P9.
  • the slurry of the cathode active material in Preparation Example 56 and the slurry of the cathode active material in Preparation Example 1 were sequentially coated on both sides of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 , and the others were the same as in Example 7. , obtain the positive electrode piece P10.
  • the slurry of the cathode active material in Preparation Example 55 and the slurry of the cathode active material in Preparation Example 56 were sequentially coated on both sides of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 , and the others were the same as in Example 7. , to obtain the positive electrode piece P11.
  • the slurry of the cathode active material in Preparation Example 56 and the slurry of the cathode active material in Preparation Example 55 were sequentially coated on both sides of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 , and the others were the same as in Example 7. , to obtain the positive electrode piece P12.
  • the slurry of the cathode active material in Preparation Example 1 and the slurry of the cathode active material in Preparation Example 55 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • On the B side of the aluminum foil The slurry of the cathode active material in Preparation Example 1 is uniformly coated, and the coating amount of the slurry is 0.020g/cm 2 . Then, it is vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted by a roller press to obtain the cathode plate P13.
  • the slurry of the cathode active material in Preparation Example 1 and the slurry of the cathode active material in Preparation Example 55 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P14.
  • the slurry of the cathode active material in Preparation Example 1 and the slurry of the cathode active material in Preparation Example 55 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P15.
  • the slurry of the cathode active material in Preparation Example 55 and the slurry of the cathode active material in Preparation Example 1 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P16.
  • the slurry of the cathode active material in Preparation Example 55 and the slurry of the cathode active material in Preparation Example 1 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P17.
  • the slurry of the cathode active material in Preparation Example 55 and the slurry of the cathode active material in Preparation Example 1 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P18.
  • the slurry of the cathode active material in Preparation Example 1 and the slurry of the cathode active material in Preparation Example 56 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P19.
  • the slurry of the cathode active material in Preparation Example 1 and the slurry of the cathode active material in Preparation Example 56 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P20.
  • the slurry of the cathode active material in Preparation Example 1 and the slurry of the cathode active material in Preparation Example 56 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P21.
  • the slurry of the cathode active material in Preparation Example 56 and the slurry of the cathode active material in Preparation Example 1 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P22.
  • the slurry of the cathode active material in Preparation Example 56 and the slurry of the cathode active material in Preparation Example 1 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P23.
  • the slurry of the cathode active material in Preparation Example 56 and the slurry of the cathode active material in Preparation Example 1 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P24.
  • the slurry of the cathode active material in Preparation Example 55 and the slurry of the cathode active material in Preparation Example 56 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P25.
  • the slurry of the cathode active material in Preparation Example 55 and the slurry of the cathode active material in Preparation Example 56 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P26.
  • the slurry of the cathode active material in Preparation Example 55 and the slurry of the cathode active material in Preparation Example 56 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P27.
  • the slurry of the cathode active material in Preparation Example 56 and the slurry of the cathode active material in Preparation Example 55 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P28.
  • the slurry of the cathode active material in Preparation Example 56 and the slurry of the cathode active material in Preparation Example 55 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P29.
  • the slurry of the cathode active material in Preparation Example 56 and the slurry of the cathode active material in Preparation Example 55 were sequentially coated on the A side of the aluminum foil.
  • the coating amount of each layer of slurry was 0.010g/cm 2 .
  • the rest was the same as in Example 13 to obtain the cathode plate P30.
  • the slurry of the positive electrode active material in Preparation Example 57 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode.
  • Film P31 The slurry of the positive electrode active material in Preparation Example 57 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode. Film P31.
  • the slurry of the positive active material in Preparation Example 58 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode.
  • the slurry of the cathode active material in Preparation Example 59 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a cathode. Film P33.
  • the slurry of the positive electrode active material in Preparation Example 60 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode.
  • Film P34 The slurry of the positive electrode active material in Preparation Example 60 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode. Film P34.
  • the slurry of the positive electrode active material in Preparation Example 61 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode.
  • Film P35 The slurry of the positive electrode active material in Preparation Example 61 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode. Film P35.
  • the slurry of the positive electrode active material in Preparation Example 62 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode.
  • Film P36 The slurry of the positive electrode active material in Preparation Example 62 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode.
  • Film P36 The slurry of the positive electrode active material in Preparation Example 62 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode.
  • Film P36 The slurry of the positive electrode
  • the slurry of the positive active material in Preparation Example 63 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019g/ cm2 , vacuum dried at a high temperature of 100 to 120°C for 14 hours, and compacted with a roller press to obtain a positive electrode. Film P37.
  • the slurry of the cathode active material in Preparation Example 64 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the cathode plate P38.
  • the slurry of the positive electrode active material in Preparation Example 65 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the positive electrode piece P39.
  • the slurry of the cathode active material in Preparation Example 66 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the cathode plate P40.
  • the slurry of the cathode active material in Preparation Example 67 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the cathode plate P41.
  • the slurry of the cathode active material in Preparation Example 68 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the cathode plate P42.
  • the slurry of the cathode active material in Preparation Example 69 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the cathode plate P3.
  • the slurry of the cathode active material in Preparation Example 70 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the cathode plate P44.
  • the slurry of the positive electrode active material in Preparation Example 71 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the positive electrode piece P45.
  • the slurry of the positive electrode active material in Preparation Example 72 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the positive electrode piece P46.
  • the slurry of the cathode active material in Preparation Example 73 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the cathode plate P47.
  • the slurry of the positive electrode active material in Preparation Example 74 was evenly coated on both sides of the current collector aluminum foil at a coating amount of 0.019 g/cm 2 , and the rest was the same as in Example 37 to obtain the positive electrode piece P48.
  • the first layer refers to the layer in contact with the surface of the aluminum foil
  • the second layer refers to the layer provided on the first layer
  • the first positive electrode active material refers to the positive electrode active material prepared in Preparation Example 1
  • the second positive electrode active material refers to the positive electrode active materials in Preparation Example 55, Preparation Example 57, and Preparation Examples 59-66.
  • the mass ratio of the negative active material artificial graphite, conductive agent superconducting carbon black (Super-P), binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethylcellulose (CMC-Na) is 95%: Dissolve 1.5%: 1.8%: 1.7% in deionized water, stir thoroughly and mix evenly to obtain a negative electrode slurry with a viscosity of 3000 mPa.s and a solid content of 52%; coat the negative electrode slurry on a 6 ⁇ m negative electrode current collector copper foil , then baked at 100°C for 4 hours to dry, and rolled to obtain a negative electrode piece with a compacted density of 1.75g/cm3.
  • ACSTEM Spherical aberration electron microscopy
  • the positive active material sample is made into a positive electrode piece according to the above-mentioned method for preparing the positive electrode piece P1, and then a full battery is prepared according to the above-mentioned "Preparation of Full Battery".
  • the full battery which has been cycled at 45°C until the capacity decays to 80%, is discharged to a cut-off voltage of 2.0V using a 0.1C rate. Then disassemble the battery, take out the negative electrode piece, randomly pick 30 discs of unit area (1540.25mm 2 ) on the negative electrode piece, and use Agilent ICP-OES730 to test the inductively coupled plasma emission spectrum (ICP). Calculate the amounts of Fe (if the Mn site of the cathode active material is doped with Fe) and Mn based on the ICP results, and then calculate the dissolution amount of Mn (and Fe doped at the Mn site) after cycles. The test standard is based on EPA-6010D-2014.
  • the drainage method is to first separately measure the gravity F 1 of the battery cell using a balance that automatically converts units based on the dial data, then completely places the battery core in deionized water (density is known to be 1g/cm 3 ), and measures the battery core at this time.
  • the battery of the embodiment always maintained an SOC of more than 99% during the experiment until the end of storage.
  • the positive electrode active material compositions of Preparation Examples 1-11 and Comparative Examples 1-8 are shown in Table 5.
  • Table 6 shows the performance data of the cathode active materials of Preparation Examples 1-11 and Comparative Examples 1-8 measured with or without electricity according to the above performance test method.
  • Table 7 shows the positive electrode active material composition of Preparation Examples 12-27.
  • Table 8 shows the performance data of the positive electrode active materials of Preparation Examples 12-27 measured according to the above performance test method with or without electricity.
  • Table 9 shows the performance data of the positive electrode active materials of Preparation Examples 28-41 measured according to the above performance test method with or without electricity.
  • Table 10 shows the performance data of the cathode active materials of Preparation Examples 42-54 measured according to the above performance testing method with or without electricity.
  • each cathode active material of the preparation example of the present application has achieved better performance than the comparative example in one or even all aspects of cycle performance, high temperature stability, gram capacity and compacted density. Effect.
  • the secondary battery is discharged at 1C for 48 minutes, then discharged at the specified maximum discharge current for 10 seconds, then left to stand for 30 minutes, and then charged at the specified maximum charging current for 10 seconds;
  • the secondary battery using the positive electrode plate P3-P30 Compared with the secondary battery using the positive electrode plate P2, the secondary battery using the positive electrode plate P3-P30 has higher energy density, higher low-temperature discharge capacity retention rate, higher specific power, and longer low-temperature cycle life. Secondary batteries with positive electrode plates P3-P5, P7, P9-P12, P14-15, P17-18, P20, P22, P24, P26-P30 have a longer normal temperature cycle life;
  • the secondary battery using the positive electrode plate P32 has higher energy density, higher low-temperature discharge capacity retention rate, higher specific power, and longer low-temperature cycle life;
  • the positive electrode pieces P41-P48 include the first positive electrode active material and the second positive electrode active material, and the positive electrode pieces P33-P40 only include the same amount of the corresponding second positive electrode active material, which is different from the positive electrode including only the second positive electrode active material.
  • the secondary battery produced by the cathode sheet including the first cathode active material and the second cathode active material has higher energy density, higher low-temperature discharge capacity retention rate, higher specific power, and longer low-temperature cycle life. ;
  • the secondary battery produced by the positive electrode sheet of the present application has higher energy density, better dynamic performance, higher cell rate performance, longer low-temperature cycle life, higher low-temperature cycle capacity retention rate, and is safer at the same time. high.

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Abstract

本申请提供了一种正极极片、二次电池、电池模块、电池包和用电装置；其中，正极极片包括正极集流体和设置在其至少一个表面上的具有单层或多层结构的正极膜层；当正极膜层为单层结构时，至少一个正极膜层同时包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料和选自LiFePO 4、碳包覆LiFePO 4、LiFe bM cPO 4和碳包覆LiFe bM cPO 4中的第二正极活性材料；和/或，当正极膜层为多层结构时，至少一个正极膜层的至少一层中同时包含第一正极活性材料和第二正极活性材料。本申请正极极片所制二次电池的能量密度高、倍率性能高、动力学性能好、低温循环寿命长、低温循环容量保持率高。

Description

正极极片、二次电池、电池模块、电池包和用电装置 技术领域
本申请涉及二次电池技术领域，尤其涉及一种正极极片、二次电池、电池模块、电池包和用电装置。
背景技术
近年来，随着二次电池的应用范围越来越广，二次电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。由于二次电池取得了极大的发展，因此对其能量密度、循环性能和安全性能等也提出了更高的要求。现有的磷酸锰铁锂使得二次电池的动力学性能较差、电芯倍率性能较低，不能满足动力电池需求。现有的磷酸铁锂作为正极活性材料所制的二次电池具有优异的循环稳定性和安全性，但其内部一维锂离子通道的存在以及充放电过程中LiFePO 4和FePO 4两相的存在使充放电过程中材料内部相变阻力变大，导致二次电池的动力学性能差、电芯倍率性能低、低温循环寿命短、低温容量保持率低。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种正极极片、二次电池、电池模块、电池包和用电装置，以解决采用现有正极活性材料所制二次电池的能量密度低、动力学性能差、倍率性能低、低温循环寿命短、低温循环容量保持率低的问题。
为了达到上述目的，本申请的第一方面提供了一种正极极片，包括正极集流体和设置在正极集流体的至少一个表面上的正极膜层；正极膜层为单层结构或多层结构；当正极膜层为单层结构时，至少一个正极膜层同时包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料和第二正极活性材料；和/或，当正极膜层为多层结构时，至少一个正极膜层的至少一层中同时包含化学式为 Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料和第二正极活性材料；其中，A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素；R包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素；C包括选自B、S、Si和N中的一种或多种元素；D包括选自S、F、Cl和Br中的一种或多种元素；a选自0.9至1.1的范围，x选自0.001至0.1的范围，y选自0.001至0.5的范围，z选自0.001至0.1的范围，n选自0.001至0.1的范围；第二正极活性材料为选自LiFePO 4、碳包覆LiFePO 4、LiFe bM cPO 4和碳包覆LiFe bM cPO 4中的一种或多种，其中，M独立地包括选自Ti、Zn、Co、Mn、La、V、Mg、Al、Nb、W、Zr、Nb、Sm、Cr、Cu和B中的一种或多种元素，b独立地选自0.99至0.999的范围且b+c＝1。
由此，本申请人意外地发现：通过在化合物LiMnPO 4的Li位、Mn位、P位和O位同时以特定量掺杂特定的元素获得第一正极活性材料，能获得明显改善的倍率性能，同时显著减少Mn与Mn位掺杂元素的溶出，获得显著改善的循环性能和/或高温稳定性，并且材料的克容量和压实密度也得到提高，界面副反应减少。
本申请通过将第一正极活性材料和第二正极活性材料混合使用，两种材料的优势互补，提升了二次电池的能量密度，同时使二次电池兼具优良的动力学性能、倍率性能、低温循环寿命和低温循环容量保持率。
本申请的第二方面还提供一种正极极片，包括正极集流体和设置在正极集流体的至少一个表面上的正极膜层；至少一个正极膜层为多层结构，任一具有多层结构的正极膜层在不同层中分别包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料和第二正极活性材料；其中，A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素；R包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素；C包括选自B、S、Si和N中的一种或多种元素；D包括选自S、F、Cl和Br中的一种或多种元素；a选自0.9至1.1的范围，x选自0.001至0.1的范围，y选自0.001至0.5的范围，z选自0.001至0.1的范围，n选自0.001至0.1的范围；第 二正极活性材料为选自LiFePO 4、碳包覆LiFePO 4、LiFe bM cPO 4和碳包覆LiFe bM cPO 4中的一种或多种，其中，M独立地包括选自Ti、Zn、Co、Mn、La、V、Mg、Al、Nb、W、Zr、Nb、Sm、Cr、Cu和B中的一种或多种元素，b独立地选自0.99至0.999的范围且b+c＝1；可选地，任一具有多层结构的正极膜层在相邻层中分别包含第一正极活性材料和第二正极活性材料。
由此，第一正极活性材料具有明显改善的倍率性能，同时显著减少Mn与Mn位掺杂元素的溶出，获得显著改善的循环性能和/或高温稳定性，并且材料的克容量和压实密度也得到提高，界面副反应减少。
本申请将第一正极活性材料和第二正极活性材料组合使用，两种材料的优势互补，提升了二次电池的能量密度，同时使二次电池兼具优良的倍率性能、动力学性能、低温循环寿命和低温循环容量保持率。
本申请的第三方面提供一种正极极片，包括正极集流体和分别设置在正极集流体的两个表面上的正极膜层A和正极膜层B；正极膜层A和正极膜层B独立地为单层结构或多层结构；正极膜层A的至少一层中包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料，同时，正极膜层B的至少一层中包含第二正极活性材料；其中，A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素；R包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素；C包括选自B、S、Si和N中的一种或多种元素；D包括选自S、F、Cl和Br中的一种或多种元素；a选自0.9至1.1的范围，x选自0.001至0.1的范围，y选自0.001至0.5的范围，z选自0.001至0.1的范围，n选自0.001至0.1的范围；第二正极活性材料选自LiFePO 4、碳包覆LiFePO 4、LiFe bM cPO 4和碳包覆LiFe bM cPO 4中的一种或多种，其中，M独立地包括选自Ti、Zn、Co、Mn、La、V、Mg、Al、Nb、W、Zr、Nb、Sm、Cr、Cu和B中的一种或多种元素，b独立地选自0.99至0.999的范围且b+c＝1。
由此，第一正极活性材料具有明显改善的倍率性能，同时显著减少Mn与Mn位掺杂元素的溶出，获得显著改善的循环性能和/或高温稳定性，并且材料的克容量和压实密度也得到提高，界面副反应减少。
本申请将第一正极活性材料和第二正极活性材料组合使用，两种材料的优势互补，提升了二次电池的能量密度，同时使二次电池兼具优良的倍率性能、动力学性能、低温循环寿命和低温循环容量保持率。
除非另有说明，否则化学式Li aA xMn 1-yR yP 1-zC zO 4-nD n中，当A为两种以上元素时，上述对于x数值范围的限定不仅是对每种作为A的元素的化学计量数的限定，也是对各个作为A的元素的化学计量数之和的限定。例如当A为两种以上元素A1、A2……An时，A1、A2……An各自的化学计量数x1、x2……xn各自均需落入本申请对x限定的数值范围内，且x1、x2……xn之和也需落入该数值范围内。类似地，对于R、C和D为两种以上元素的情况，本申请中对R、C和D化学计量数的数值范围的限定也具有上述含义。
除非另有说明，否则化学式LiFe bM cPO 4中，当M为两种以上元素时，上述对于c数值范围的限定不仅是对每种作为M的元素的化学计量数的限定，也是对各个作为M的元素的化学计量数之和的限定。例如当M为两种以上元素M1、M2……Mn时，M1、M2……Mn各自的化学计量数c1、c2……cn各自均需落入本申请对c限定的数值范围内，且c1、c2……cn之和也需落入该数值范围内。
在第一方面至第三方面的任意实施方式中，第二正极活性材料中，碳质量占碳包覆LiFePO 4的质量的0.1％-4％；和/或，碳质量占碳包覆LiFe bM cPO 4的质量的0.1％-4％。采用上述碳质量含量的第二正极活性材料，能进一步保证二次电池具有优良的倍率性能、动力学性能和低温循环性能，且具有较高的能量密度。
在第一方面至第三方面的任意实施方式中，第一正极活性材料与第二正极活性材料的质量比为1:7-7:1，可选为1:4-4:1。以保证二次电池兼具较高的能量密度、优良的动力学性能、优良的倍率性能、较长的低温循环寿命和较高的低温循环容量保持率，减少界面副反应。
在第一方面至第三方面的任意实施方式中，第一正极活性材料中，R选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的至少两种元素。由此，可更准确地控制第一正极活性材料的组成。
在第一方面至第三方面的任意实施方式中，第一正极活性材料中， A为选自Mg和Nb中的任一种元素；和/或，R为选自Fe、Ti、V、Co和Mg中的至少两种元素，可选地为Fe与选自Ti、V、Co和Mg中的一种以上元素；和/或，C为S；和/或，D为F。通过在上述范围内对掺杂元素进行选择，能进一步地改善二次电池的倍率性能、提高电子电导率，从而提升二次电池的倍率性能、克容量和高温性能，减轻界面的副反应。
在第一方面至第三方面的任意实施方式中，第一正极活性材料中，x选自0.001-0.005的范围。通过在该范围内对x值进行选择，能进一步提升第一正极活性材料的动力学性能。
在第一方面至第三方面的任意实施方式中，第一正极活性材料中，y选自0.01至0.5的范围，可选地选自0.25至0.5的范围。通过在该范围内对y值进行选择，能进一步提升第一正极活性材料的克容量和倍率性能。
在第一方面至第三方面的任意实施方式中，第一正极活性材料中，z选自0.001至0.005的范围。通过在该范围内对z值进行选择，能进一步提升二次电池的倍率性能。
在第一方面至第三方面的任意实施方式中，第一正极活性材料中，n选自0.001至0.005的范围。通过在该范围内对n值进行选择，能进一步提升二次电池的高温性能。
在第一方面至第三方面的任意实施方式中，第一正极活性材料中，(1-y)与y的比值选自1-4，可选为选自1.5-3。这样可以使二次电池的能量密度和循环性能进一步提升。
在第一方面至第三方面的任意实施方式中，第一正极活性材料中，a与x的比值选自9-1100，可选为选自190-998。在满足这一条件时，使二次电池的能量密度和循环性能进一步提升。
在第一方面至第三方面的任意实施方式中，第一正极活性材料的晶格变化率为8％以下，可选地为4％以下。通过降低晶格变化率，有利于改善二次电池的倍率性能。晶格变化率可通过本领域中已知的方法，例如X射线衍射图谱(XRD)测得。
在第一方面至第三方面的任意实施方式中，第一正极活性材料的 Li/Mn反位缺陷浓度为2％以下，可选地为0.5％以下。所谓Li/Mn反位缺陷，指的是LiMnPO 4晶格中，Li +与Mn 2+的位置发生互换。Li/Mn反位缺陷浓度指的是正极活性材料中与Mn 2+发生互换的Li +占Li +总量的百分比。通过降低Li/Mn反位缺陷浓度，有利于提高第一正极活性材料的克容量和倍率性能。Li/Mn反位缺陷浓度可通过本领域中已知的方法，例如XRD测得。
在第一方面至第三方面的任意实施方式中，第一正极活性材料的表面氧价态为-1.82以下，可选地为-1.89～-1.98。通过降低表面氧价态，能够减轻第一正极活性材料与电解液的界面副反应，从而改善二次电池的循环性能和高温稳定性。表面氧价态可通过本领域中已知的方法测量，例如通过电子能量损失谱(EELS)测量。
在第一方面至第三方面的任意实施方式中，第一正极活性材料在3T下的压实密度为2.0g/cm 3以上，可选地为2.2g/cm 3以上。压实密度越高，单位体积的第一正极活性材料的重量越大，因此提高压实密度有利于提高电芯的体积能量密度。压实密度可依据GB/T24533-2009测量。
在第一方面至第三方面的任意实施方式中，第一正极活性材料的表面还包覆有碳。由此，可以改善第一正极活性材料的导电性。
在第一方面至第三方面的任意实施方式中，第一正极活性材料和第二正极活性材料的质量之和占正极极片的质量的88％-98.7％。进一步保证二次电池具有优良的倍率性能、动力学性能和低温循环性能，且具有较高的能量密度。
本申请的第四方面提供一种二次电池，包括本申请第一方面至第三方面中任一的正极极片。
本申请的第五方面提供一种电池模块，包括本申请的第四方面的二次电池。
本申请的第六方面提供一种电池包，包括本申请的第五方面的电池模块。
本申请的第七方面提供一种用电装置，包括选自本申请的第四方面的二次电池、本申请的第五方面的电池模块和本申请的第六方面的 电池包中的至少一种。
附图说明
图1是本申请一实施方式的二次电池的示意图。
图2是图1所示的本申请一实施方式的二次电池的分解图。
图3是本申请一实施方式的电池模块的示意图。
图4是本申请一实施方式的电池包的示意图。
图5是图4所示的本申请一实施方式的电池包的分解图。
图6是本申请一实施方式的二次电池用作电源的用电装置的示意图。
图7是本申请正极极片P1所制电池结构的示意图。
图8是本申请正极极片P2所制电池结构的示意图。
图9是本申请正极极片P3所制电池结构的示意图。
图10是本申请正极极片P8所制电池结构的示意图。
图11是本申请正极极片P10所制电池结构的示意图。
图12是本申请正极极片P11所制电池结构的示意图。
图13是本申请正极极片P12所制电池结构的示意图。
图14是本申请正极极片P17所制电池结构的示意图。
图15是本申请正极极片P18所制电池结构的示意图。
图16是本申请正极极片P23所制电池结构的示意图。
图17是本申请正极极片P24所制电池结构的示意图。
图18是本申请正极极片P26所制电池结构的示意图。
图19是本申请正极极片P27所制电池结构的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53顶盖组件。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的正极极片、二次电池、电池模块、电池包和用电装置的实施方式。但是会有省略 不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，方法包括步骤(a)和(b)，表示方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，提到方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到方法，例如，方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，“包括”和“包含”表示还可以包括或包含 没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
[二次电池]
二次电池又称为充电电池或蓄电池，是指在电池放电后可通过充电的方式使活性材料激活而继续使用的电池。
通常情况下，二次电池包括正极极片、负极极片、隔离膜及电解液。在电池充放电过程中，活性离子(例如锂离子)在正极极片和负极极片之间往返嵌入和脱出。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使活性离子通过。电解液在正极极片和负极极片之间，主要起到传导活性离子的作用。
[正极极片]
本申请第一个方面的实施方式提供一种正极极片，包括正极集流体和设置在正极集流体的至少一个表面上的正极膜层；正极膜层为单层结构或多层结构；当正极膜层为单层结构时，至少一个正极膜层同时包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料和第二正极活性材料；和/或，当正极膜层为多层结构时，至少一个正极膜层的至少一层中同时包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料和第二正极活性材料；其中，A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素；R包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素；C包括选自B、S、Si和N中的一种或多种元素；D包括选自S、F、Cl和Br中的一种或多种元素；a选自0.9至1.1的范围，x选自0.001至0.1的范围，y选自0.001至0.5的范围，z选自0.001至0.1的范围，n选自0.001至0.1的范围；第二正极活性材料为选自LiFePO 4、 碳包覆LiFePO 4、LiFe bM cPO 4和碳包覆LiFe bM cPO 4中的一种或多种，其中，M独立地包括选自Ti、Zn、Co、Mn、La、V、Mg、Al、Nb、W、Zr、Nb、Sm、Cr、Cu和B中的一种或多种元素，b独立地选自0.99至0.999的范围且b+c＝1。
需要说明的是：当正极极片包括两个正极膜层时，“正极膜层为单层结构或多层结构”指两个正极膜层各自独立地为单层结构或多层结构；“当正极膜层为单层结构时”指一个或两个正极膜层为单层结构时；“当正极膜层为多层结构时”指一个或两个正极膜层为多层结构时。
本申请的第一正极活性材料通过在化合物LiMnPO 4中进行元素掺杂而获得，其中，A、R、C和D分别为在化合物LiMnPO 4的Li位、Mn位、P位和O位掺杂的元素。不希望囿于理论，本申请发明人发现磷酸锰锂的性能提升与减小脱嵌锂过程中磷酸锰锂的晶格变化率和降低表面活性有关。减小晶格变化率可减小晶界处两相间的晶格常数差异，减小界面应力，增强Li +在界面处的传输能力，从而提升正极活性材料的倍率性能。而表面活性高容易导致界面副反应严重，加剧产气、电解液消耗和破坏界面，从而影响二次电池的循环等性能。本申请中，通过Li和Mn位掺杂减小了晶格变化率。Mn位掺杂还有效降低表面活性，从而抑制Mn溶出和正极活性材料与电解液的界面副反应。P位掺杂使Mn-O键长的变化速率更快，降低材料的小极化子迁移势垒，从而有利于电子电导率。O位掺杂对减小界面副反应有良好的作用。P位和O位的掺杂还对反位缺陷的Mn溶出及动力学性能产生影响。因此，掺杂减小了材料中反位缺陷浓度，提高材料的动力学性能和克容量，还可以改变颗粒的形貌，从而提升压实密度。本申请人意外地发现：通过在化合物LiMnPO 4的Li位、Mn位、P位和O位同时以特定量掺杂特定的元素，能够获得明显改善的倍率性能，同时显著减少了Mn与Mn位掺杂元素的溶出，获得了显著改善的循环性能和/或高温稳定性，并且材料的克容量和压实密度也可以得到提高。另外，本申请通过将第一正极活性材料和第二正极活性材料混合使用，两种材料的优势互补，提升了二次电池的能量密度；第一正极活性材料均匀分散在第二正极活性材料周围，第一正极活性材料其 Li位、P位、Mn位的掺杂能够进一步减小脱锂过程中的晶格变化率以及提高电子电导率，从而能整体提高混合使用的材料的导电性及脱嵌锂速率，从而提高了二次电池的能量密度并使混合使用的材料具有优异的功率性能和低温性能。另外，得益于第一正极材料O位的掺杂使得界面副反应减小，使具有良好的循环稳定性，不会恶化循环性能。第二材料其稳定的骨架结构在混合材料中有利于提高第一正极材料的稳定性，从而使得二次电池具有优良的循环性能。
在第一个方面的一些实施方式中，在正极集流体的两个表面上分别设置有正极膜层C和正极膜层D，正极膜层C为多层结构，正极膜层D为单层结构，正极膜层C中的至少一层同时包含第一正极活性材料和第二正极活性材料；可选地，正极膜层D包含第一正极活性材料和第二正极活性材料中的一种或两种；可选地，正极膜层C中的其余层包含第一正极活性材料或第二正极活性材料。
在第一个方面的一些实施方式中，在正极集流体的两个表面上分别设置有正极膜层C和正极膜层D，正极膜层C为多层结构，正极膜层D为单层结构，正极膜层D同时包含第一正极活性材料和第二正极活性材料；可选地，正极膜层C中的任一层包含第一正极活性材料或第二正极活性材料。
在第一个方面的一些实施方式中，在正极集流体的两个表面上分别设置有一个正极膜层，每个正极膜层都为多层结构，每个正极膜层中的至少一层同时包含第一正极活性材料和第二正极活性材料；可选地，正极膜层中的其余层包含第一正极活性材料或第二正极活性材料。
本申请第二个方面的实施方式提供一种正极极片，包括正极集流体和设置在正极集流体的至少一个表面上的正极膜层；至少一个正极膜层为多层结构，任一具有多层结构的正极膜层在不同层中分别包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料和第二正极活性材料；其中，A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素；R包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素；C包括选自B、S、Si和N中的一种或多种元素；D包括选自S、F、Cl和Br中的一种或多种元 素；a选自0.9至1.1的范围，x选自0.001至0.1的范围，y选自0.001至0.5的范围，z选自0.001至0.1的范围，n选自0.001至0.1的范围；第二正极活性材料为选自LiFePO 4、碳包覆LiFePO 4、LiFe bM cPO 4和碳包覆LiFe bM cPO 4中的一种或多种，其中，M独立地包括选自Ti、Zn、Co、Mn、La、V、Mg、Al、Nb、W、Zr、Nb、Sm、Cr、Cu和B中的一种或多种元素，b独立地选自0.99至0.999的范围且b+c＝1；可选地，任一具有多层结构的正极膜层在相邻层中分别包含第一正极活性材料和第二正极活性材料。
在第二个方面的一些实施方式中，在正极集流体的两个表面上分别设置有一个正极膜层，每个正极膜层都为多层结构，每个正极膜层中的相邻两层分别包含第一正极活性材料和第二正极活性材料。
在第二个方面的一些实施方式中，在正极集流体的两个表面上分别设置有正极膜层E和正极膜层F，正极膜层E为多层结构，正极膜层F为单层结构，正极膜层E中的相邻两层分别包含第一正极活性材料和第二正极活性材料；可选地，正极膜层E中的其余层和正极膜层F包含第一正极活性材料或第二正极活性材料。
本申请第三个方面的实施方式提供一种正极极片，包括正极集流体和分别设置在正极集流体的两个表面上的正极膜层A和正极膜层B；正极膜层A和正极膜层B独立地为单层结构或多层结构；正极膜层A的至少一层中包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料，同时，正极膜层B的至少一层中包含第二正极活性材料；其中，A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素；R包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素；C包括选自B、S、Si和N中的一种或多种元素；D包括选自S、F、Cl和Br中的一种或多种元素；a选自0.9至1.1的范围，x选自0.001至0.1的范围，y选自0.001至0.5的范围，z选自0.001至0.1的范围，n选自0.001至0.1的范围；第二正极活性材料选自LiFePO 4、碳包覆LiFePO 4、LiFe bM cPO 4和碳包覆LiFe bM cPO 4中的一种或多种，其中，M独立地包括选自Ti、Zn、Co、Mn、La、V、Mg、Al、Nb、W、Zr、Nb、Sm、Cr、Cu和B中 的一种或多种元素，b独立地选自0.99至0.999的范围且b+c＝1。
本申请第二个或第三个方面的实施方式中，第一正极活性材料具有明显改善的倍率性能，同时显著减少Mn与Mn位掺杂元素的溶出，获得显著改善的循环性能和/或高温稳定性，并且材料的克容量和压实密度也得到提高，界面副反应减少，具体原理同本申请第一个实施方式中。虽然机理并不十分清楚，但是本申请通过将第一正极活性材料和第二正极活性材料组合使用，两种材料的优势互补，提升了二次电池的能量密度，同时使二次电池兼具优良的倍率性能、动力学性能、低温循环寿命和低温循环容量保持率。具体来说，第一正极活性材料均匀分散在第二正极活性材料周围，第一正极活性材料其Li位、P位、Mn位的掺杂能够进一步减小脱锂过程中的晶格变化率以及提高电子电导率，从而能整体提高混合使用的材料的导电性及脱嵌锂速率，从而提高了二次电池的能量密度并使混合使用的材料具有优异的功率性能和低温性能。另外，得益于第一正极材料O位的掺杂使得界面副反应减小，使具有良好的循环稳定性，不会恶化循环性能。第二材料其稳定的骨架结构在混合材料中有利于提高第一正极材料的稳定性，从而使得二次电池具有优良的循环性能。
除非另有说明，否则化学式Li aA xMn 1-yR yP 1-zC zO 4-nD n中，当A为两种以上元素时，上述对于x数值范围的限定不仅是对每种作为A的元素的化学计量数的限定，也是对各个作为A的元素的化学计量数之和的限定。例如当A为两种以上元素A1、A2……An时，A1、A2……An各自的化学计量数x1、x2……xn各自均需落入本申请对x限定的数值范围内，且x1、x2……xn之和也需落入该数值范围内。类似地，对于R、C和D为两种以上元素的情况，本申请中对R、C和D化学计量数的数值范围的限定也具有上述含义。
除非另有说明，否则化学式LiFe bM cPO 4中，当M为两种以上元素时，上述对于c数值范围的限定不仅是对每种作为M的元素的化学计量数的限定，也是对各个作为M的元素的化学计量数之和的限定。例如当M为两种以上元素M1、M2……Mn时，M1、M2……Mn各自的化学计量数c1、c2……cn各自均需落入本申请对c限定的数 值范围内，且c1、c2……cn之和也需落入该数值范围内。
在第一个至第三个方面的一些实施方式中，第一正极活性材料Li aA xMn 1-yR yP 1-zC zO 4-nD n整个保持电中性。
在第一个至第三个方面的一些实施方式中，LiFe bM cPO 4整个保持电中性。
在第一方面至第三方面的一些实施方式中，第二正极活性材料中，碳质量占碳包覆LiFePO 4的质量的0.1％-4％；和/或，碳质量占碳包覆LiFe bM cPO 4的质量的0.1％-4％。采用上述碳质量含量的第二正极活性材料，能进一步保证二次电池具有优良的倍率性能、动力学性能和低温循环性能，且具有较高的能量密度。
在第一个至第三个方面的一些实施方式中，第一活性材料与第二活性材料的质量比为1:7-7:1，可选为1:4-4:1，进一步可选为1:3-3:1，例如1:7、1:5、1:3、1:2、3:5、1:1、5:3、2:1、3:1、5:1、7:1。以保证二次电池兼具较高的能量密度、优良的动力学性能、优良的倍率性能、较长的低温循环寿命和较高的低温循环容量保持率，减少界面副反应。
在第一个至第三个方面的一些实施方式中，第一正极活性材料中，R选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的至少两种元素。由此，能够更容易且准确地控制第一正极活性材料的组成。
在第一个至第三个方面的一些实施方式中，第一正极活性材料中，A为选自Mg和Nb中的任一种元素；和/或，R为选自Fe、Ti、V、Co和Mg中的至少两种元素，可选地为Fe与选自Ti、V、Co和Mg中的一种以上元素；和/或，C为S；和/或，D为F。通过在上述范围内对Li位掺杂元素进行选择，能够进一步减小脱锂过程中的晶格变化率，从而进一步改善二次电池的倍率性能。通过在上述范围内对Mn位掺杂元素进行选择，能够进一步提高电子电导率并进一步减小晶格变化率，从而提升二次电池的倍率性能和克容量。通过在上述范围内对P位掺杂元素进行选择，能够进一步改善二次电池的倍率性能。通过在上述范围内对O位掺杂元素进行选择，能够进一步减轻界面 的副反应，提升二次电池的高温性能。
在第一个至第三个方面的一些实施方式中，第一正极活性材料中，x选自0.001-0.005的范围。通过在该范围内对x值进行选择，能进一步提升第一正极活性材料的动力学性能。
在第一个至第三个方面的一些实施方式中，第一正极活性材料中，y选自0.01至0.5的范围，可选地选自0.25至0.5的范围。通过在该范围内对y值进行选择，能进一步提升第一正极活性材料的克容量和倍率性能。
在第一个至第三个方面的一些实施方式中，第一正极活性材料中，z选自0.001至0.005的范围。通过在该范围内对z值进行选择，能进一步提升二次电池的倍率性能。
在第一个至第三个方面的一些实施方式中，第一正极活性材料中，n选自0.001至0.005的范围。通过在该范围内对n值进行选择，能进一步提升二次电池的高温性能。
在第一个至第三个方面的一些实施方式中，第一正极活性材料中，(1-y)与y的比值选自1-4，可选为选自1.5-3，且a与x的比值选自9-1100，可选为选自190-998。在满足这一条件时，使二次电池的能量密度和循环性能进一步提升。
在第一个至第三个方面的一些实施方式中，第一正极活性材料的晶格变化率为8％以下，可选地为4％以下。通过降低晶格变化率，能够使得Li离子传输更容易，即Li离子在材料中的迁移能力更强，有利于改善二次电池的倍率性能。晶格变化率可通过本领域中已知的方法，例如X射线衍射图谱(XRD)测得。
在第一个至第三个方面的一些实施方式中，第一正极活性材料的Li/Mn反位缺陷浓度为2％以下，可选地为0.5％以下。所谓Li/Mn反位缺陷，指的是LiMnPO 4晶格中，Li +与Mn 2+的位置发生互换。Li/Mn反位缺陷浓度指的是正极活性材料中与Mn 2+发生互换的Li +占Li +总量的百分比。通过降低Li/Mn反位缺陷浓度，有利于提高第一正极活性材料的克容量和倍率性能。Li/Mn反位缺陷浓度可通过本领域中已知的方法，例如XRD测得。
在第一个至第三个方面的一些实施方式中，第一正极活性材料的表面氧价态为-1.82以下，可选地为-1.89～-1.98。通过降低表面氧价态，能够减轻第一正极活性材料与电解液的界面副反应，从而改善二次电池的循环性能和高温稳定性。表面氧价态可通过本领域中已知的方法测量，例如通过电子能量损失谱(EELS)测量。
在第一个至第三个方面的一些实施方式中，第一正极活性材料在3T下的压实密度为2.0g/cm 3以上，可选地为2.2g/cm 3以上。压实密度越高，单位体积的第一正极活性材料的重量越大，因此提高压实密度有利于提高电芯的体积能量密度。压实密度可依据GB/T24533-2009测量。
在第一个至第三个方面的一些实施方式中，第一正极活性材料的表面还包覆有碳。由此，可以改善第一正极活性材料的导电性。
在第一个至第三个方面的一些实施方式中，第一正极活性材料和第二正极活性材料的质量之和占正极极片的质量的88％-98.7％。进一步保证二次电池具有优良的倍率性能、动力学性能和低温循环性能，且具有较高的能量密度。
在第一个至第三个方面的一些实施方式中，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在第一个至第三个方面的一些实施方式中，正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在第一个至第三个方面的一些实施方式中，正极膜层还可包含本领域公知的用于二次电池的其它正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料， 还可以使用其他可被用作二次电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在第一个至第三个方面的一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在第一个至第三个方面的一些实施方式中，正极膜层还可选地包括导电剂。作为示例，导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在第一个至第三个方面的一些实施方式中，化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料通过以下的步骤制备：
步骤(1)：将锰源、元素R的源、酸和可选的溶剂混合，得到混合物；
步骤(2)：将混合物与锂源、磷源、元素A的源、元素C的源和元素D的源及可选的溶剂混合，干燥，烧结，得到包含Li aA xMn 1-yR yP 1-zC zO 4-nD n的内核材料。A、R、C、D的定义如前面所述。
在第一个至第三个方面的一些实施方式中，步骤(1)在60℃-120℃下进行混合；和/或，步骤(1)中，通过以200-800rpm转速搅拌进行混合。
在第一个至第三个方面的一些实施方式中，步骤(2)中，混合进行8-15小时。
在第一个至第三个方面的一些实施方式中，步骤(2)中，烧结 在600℃-900℃下进行6-14小时。
在第一个至第三个方面的一些实施方式中，元素A的源为选自元素A的单质、氧化物、磷酸盐、草酸盐、碳酸盐和硫酸盐中的一种或多种；和/或，
元素R的源为选自元素R的单质、氧化物、磷酸盐、草酸盐、碳酸盐和硫酸盐中的一种或多种；和/或，
元素C的源为选自元素C的硫酸盐、硼酸盐、硝酸盐和硅酸盐中的一种或多种；和/或，
元素D的源为选自元素D的单质和铵盐中的一种或多种。
本申请中，锰源可为本领域已知的可用于制备磷酸锰锂的含锰物质。作为示例，锰源可为选自单质锰、二氧化锰、磷酸锰、草酸锰、碳酸锰中的一种或多种。
本申请中，酸可为选自盐酸、硫酸、硝酸、磷酸、硅酸、亚硅酸等有机酸和有机酸如草酸中的一种或多种。在一些实施方式中，酸为浓度为60重量％以下的稀的有机酸。
本申请中，锂源可为本领域已知的可用于制备磷酸锰锂的含锂物质。作为示例，锂源为选自碳酸锂、氢氧化锂、磷酸锂、磷酸二氢锂中的一种或多种。
本申请中，磷源可为本领域已知的可用于制备磷酸锰锂的含磷物质。作为示例，磷源为选自磷酸氢二铵、磷酸二氢铵、磷酸铵和磷酸中的一种或多种。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体 可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于二次电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极膜层还可选地包括粘结剂。作为示例，粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极膜层还可选地包括导电剂。作为示例，导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，电解质为液态的，且包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，电解液还可选地包括添加剂。作为示例，添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，上述的正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸 丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于开口，以封闭容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图4和图5是作为一个示例的电池包1。参照图4和图5，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。二次电池、电池模块、 或电池包可以用作用电装置的电源，也可以用作用电装置的能量存储单元。用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图6是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
[实施例]
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
正极活性材料及其浆料的制备
制备例1
制备掺杂的草酸锰：将1.3mol MnSO 4·H 2O与0.7mol FeSO 4·H 2O在混料机中充分混合6小时；将混合物转移至反应釜中，加入10L去离子水和2mol二水合草酸，加热至80℃，之后以600rpm转速搅拌6小时，反应终止(无气泡产生)，得到Fe掺杂的草酸锰的悬浮液；过滤悬浮液，滤饼在120℃下烘干，研磨，得到粒径Dv 50为100nm左右的Fe掺杂的草酸锰颗粒；
制备掺杂的磷酸锰锂：取1mol Fe掺杂的草酸锰颗粒、0.497mol碳酸锂、0.001mol的Mo(SO 4) 3、含有0.999mol磷酸的浓度85％的磷酸水溶液、0.001mol的H 4SiO 4、0.0005mol的NH 4HF 2和0.005mol蔗糖加入到20L去离子水中，将混合物转入砂磨机中充分研磨搅拌10 小时，得到浆料；将浆料转移到喷雾干燥设备中进行喷雾干燥造粒，设定干燥温度为250℃，干燥4小时，得到颗粒；在氮气(90％v/v)+氢气(10％v/v)保护气氛中，将颗粒在700℃下烧结10小时，得到正极活性材料1，碳包覆的Li 0.994Mo 0.001Mn 0.65Fe 0.35P 0.999Si 0.001O 3.999F 0.001。正极活性材料可用电感耦合等离子体发射光谱(ICP)进行元素含量的检测。
制备例2
除了将高纯Li 2CO 3的量改变为0.4885mol，将Mo(SO 4) 3换成等摩尔的MgSO 4，将FeSO 4﹒H 2O的量改变为0.68mol，在制备掺杂的草酸锰时还加入0.02mol的Ti(SO 4) 2，并将H 4SiO 4换成等摩尔的HNO 3之外，其他与制备例1相同。
制备例3
除了在将高纯Li 2CO 3的量改变为0.496mol，将Mo(SO 4) 3换成等摩尔的W(SO 4) 3，将H 4SiO 4换成等摩尔的H 2SO 4之外，其他与制备例1相同。
制备例4
除了将高纯Li 2CO 3的量改变为0.4985mol，将0.001mol的Mo(SO 4) 3换成0.0005mol的Al 2(SO 4) 3和NH 4HF 2换成等摩尔的NH 4HCl 2之外，其他与制备例1相同。
制备例5
除了将0.7mol的FeSO 4﹒H 2O改为0.69mol，在制备掺杂的草酸锰时还加入0.01molVCl 2，将Li 2CO 3的量改变为0.4965mol，将0.001mol的Mo(SO 4) 3换成0.0005mol的Nb 2(SO 4) 5和H 4SiO 4换成等摩尔的H 2SO 4之外，其他与制备例1相同。
制备例6
除了将FeSO 4﹒H 2O的量改为0.68mol，在制备掺杂的草酸锰时还加入0.01mol的VCl 2和0.01mol的MgSO 4，将Li 2CO 3的量改变为0.4965mol，将0.001mol的Mo(SO 4) 3换成0.0005mol的Nb 2(SO 4) 5和H 4SiO 4换成等摩尔的H 2SO 4之外，其他与制备例1相同。
制备例7
除了将MgSO 4换成等摩尔的CoSO 4之外，其他与制备例6相同。
制备例8
除了将MgSO 4换成等摩尔的NiSO 4之外，其他与制备例6相同。
制备例9
除了将FeSO 4﹒H 2O的量改为0.698mol，在制备掺杂的草酸锰时还加入0.002mol的Ti(SO 4) 2，将Li 2CO 3的量改变为0.4955mol，将0.001mol的Mo(SO 4) 3换成0.0005mol的Nb 2(SO 4) 5，H 4SiO 4换成等摩尔的H 2SO 4，NH 4HF 2换成等摩尔的NH 4HCl 2之外，其他与制备例1相同。
制备例10
除了将FeSO 4﹒H 2O的量改为0.68mol，在制备掺杂的草酸锰时还加入0.01mol的VCl 2和0.01mol的MgSO 4，将Li 2CO 3的量改变为0.4975mol，将0.001mol的Mo(SO 4) 3换成0.0005mol的Nb 2(SO 4) 5和NH 4HF 2换成等摩尔的NH 4HBr 2之外，其他与制备例1相同。
制备例11
除了将FeSO 4﹒H 2O的量改为0.69mol，在制备掺杂的草酸锰时还加入0.01mol的VCl 2，将Li 2CO 3的量改变为0.499mol，将Mo(SO 4) 3换成等摩尔的MgSO 4和NH 4HF 2换成等摩尔的NH 4HBr 2之外，其他与制备例1相同。
制备例12
除了将MnSO 4﹒H 2O的量改为1.36mol，将FeSO 4﹒H 2O的量改为0.6mol，在制备掺杂的草酸锰时还加入0.04mol的VCl 2，将Li 2CO 3的量改变为0.4985mol，将Mo(SO 4) 3换成等摩尔的MgSO 4和H 4SiO 4换成等摩尔的HNO 3之外，其他与制备例1相同。
制备例13
除了将MnSO 4﹒H 2O的量改为1.16mol，FeSO 4﹒H 2O的量改为0.8mol之外，其他与制备例12相同。
制备例14
除了将MnSO 4﹒H 2O的量改为1.3mol，VCl 2的量改为0.1mol之外，其他与制备例12相同。
制备例15
除了将MnSO 4﹒H 2O的量改为1.2mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2，将Li 2CO 3的量改变为0.494mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4和H 4SiO 4换成等摩尔的H 2SO 4之外，其他与制备例1相同。
制备例16
除了将MnSO 4﹒H 2O的量改为1.2mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2，将Li 2CO 3的量改变为0.467mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，0.001mol的H 4SiO 4换成0.005mol的H 2SO 4和1.175mol浓度为85％的磷酸换成1.171mol浓度为85％的磷酸之外，其他与制备例1相同。
制备例17
除了将MnSO 4﹒H 2O的量改为1.2mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2，将Li 2CO 3的量改变为0.492mol，将0.001mol 的Mo(SO 4) 3换成0.005mol的MgSO 4，H 4SiO 4换成等摩尔的H 2SO 4和0.0005mol的NH 4HF 2改成0.0025mol之外，其他与制备例1相同。
制备例18
除了将FeSO 4﹒H 2O的量改为0.5mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2和0.1mol的CoSO 4，将Li 2CO 3的量改变为0.492mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，H 4SiO 4换成等摩尔的H 2SO 4和0.0005mol的NH 4HF 2改成0.0025mol之外，其他与制备例1相同。
制备例19
除了将FeSO 4﹒H 2O的量改为0.4mol，将0.1mol的CoSO 4改为0.2mol之外，其他与制备例18相同。
制备例20
除了将MnSO 4﹒H 2O的量改为1.5mol，FeSO 4﹒H 2O的量改为0.1mol，CoSO 4的量改为0.3mol之外，其他与制备例18相同。
制备例21
除了将0.1mol的CoSO 4换成0.1mol的NiSO 4之外，其他与制备例18相同。
制备例22
除了将MnSO 4﹒H 2O的量改为1.5mol，FeSO 4﹒H 2O的量改为0.2mol，将0.1mol的CoSO 4换成0.2mol的NiSO 4之外，其他与制备例18相同。
制备例23
除了将MnSO 4﹒H 2O的量改为1.4mol，FeSO 4﹒H 2O的量改为0.3mol，CoSO 4的量改为0.2mol之外，其他与制备例18相同。
制备例24
除了将1.3mol的MnSO 4﹒H 2O改为1.2mol，0.7mol的FeSO 4﹒H 2O改为0.5mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2和0.2mol的CoSO 4，将Li 2CO 3的量改变为0.497mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，H 4SiO 4换成等摩尔的H 2SO 4和0.0005mol的NH 4HF 2改成0.0025mol之外，其他与制备例1相同。
制备例25
除了将MnSO 4﹒H 2O的量改为1.0mol，FeSO 4﹒H 2O的量改为0.7mol，CoSO 4的量改为0.2mol之外，其他与制备例18相同。
制备例26
除了将MnSO 4﹒H 2O的量改为1.4mol，FeSO 4﹒H 2O的量改为0.3mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2和0.2mol的CoSO 4，将Li 2CO 3的量改变为0.4825mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，H 4SiO 4的量改成0.1mol，磷酸的量改成0.9mol和NH 4HF 2的量改成0.04mol之外，其他与制备例1相同。
制备例27
除了将MnSO 4﹒H 2O的量改为1.4mol，FeSO 4﹒H 2O的量改为0.3mol，在制备掺杂的草酸锰时还加入0.1mol的VCl 2和0.2mol的CoSO 4，将Li 2CO 3的量改变为0.485mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，H 4SiO 4的量改成0.08mol，磷酸的量改成0.92mol和NH 4HF 2的量改成0.05mol之外，其他与制备例1相同。
制备例28-41
按照与制备例1相同的方式制备正极活性材料，但改变制备掺杂的草酸锰时的搅拌转速、温度、在砂磨机中研磨搅拌的时间、烧结温度和烧结时间，具体如下表1所示。
表1制备例28-41中制备掺杂的草酸锰时的搅拌转速、温度、在砂磨机中研磨搅拌的时间、烧结温度和烧结时间
Figure PCTCN2022084258-appb-000001
制备例42-54
按照与制备例1相同的方式制备正极活性材料，但改变锂源、锰源、磷源和掺杂元素A、B、C、D的源，具体如下表2所示。制得的正极活性材料组成与实施例1相同，即，均为Li 0.994Mo 0.001Mn 0.65Fe 0.35P 0.999Si 0.001O 3.999F 0.001。
表2制备例42-54中锂源、锰源、磷源和掺杂元素A、B、C、D的源
Figure PCTCN2022084258-appb-000002
Figure PCTCN2022084258-appb-000003
制备例55-制备例74
制备例55-制备例74的正极活性材料如表3所示。
表3制备例55-制备例74的正极活性材料
Figure PCTCN2022084258-appb-000004
Figure PCTCN2022084258-appb-000005
对比例1
制备草酸锰：将1mol的MnSO 4﹒H 2O加至反应釜中，并加入10L去离子水和1mol二水合草酸(以草酸计)。将反应釜加热至80℃，以600rpm的转速搅拌6小时,反应终止(无气泡产生)，得到草酸锰悬浮液。然后过滤悬浮液，将滤饼在120℃下烘干，之后进行研磨，得到中值粒径Dv 50为50-200nm的草酸锰颗粒。
制备磷酸锰锂：取1mol上述草酸锰颗粒、0.5mol碳酸锂、含有1mol磷酸的浓度为85％的磷酸水溶液和0.005mol蔗糖加入到20L去离子水中。将混合物转入砂磨机中充分研磨搅拌10小时，得到浆料。将浆料转移到喷雾干燥设备中进行喷雾干燥造粒，设定干燥温度为250℃，干燥4小时，得到颗粒。在氮气(90体积％)+氢气(10体积％)保护气氛中，将上述粉料在700℃下烧结10小时，得到碳包覆的LiMnPO 4。
对比例2
除了在对比例1中，将1mol的MnSO 4﹒H 2O换成0.85mol的MnSO 4﹒H 2O和0.15mol的FeSO 4﹒H 2O，并加入到混料机中充分混合6小时之后再加入反应釜之外，其它与对比例1相同。
对比例3
除了将MnSO 4﹒H 2O的量改为1.9mol，0.7mol的FeSO 4﹒H 2O 换成0.1mol的ZnSO 4，将Li 2CO 3的量改变为0.495mol，将0.001mol的Mo(SO 4) 3换成0.005mol的MgSO 4，将磷酸的量改成1mol，不加入H 4SiO 4和NH 4HF 2之外，其他与制备例1相同。
对比例4
除了将MnSO 4﹒H 2O的量改为1.2mol，FeSO 4﹒H 2O的量改为0.8mol，将Li 2CO 3的量改变为0.45mol，将0.001mol的Mo(SO 4) 3换成0.005mol的Nb 2(SO 4) 5，将0.999mol的磷酸改成1mol，0.0005mol的NH 4HF 2改成0.025mol，不加入H 4SiO 4之外，其他与制备例1相同。
对比例5
除了将MnSO 4﹒H 2O的量改为1.4mol，FeSO 4﹒H 2O的量改为0.6mol，将Li 2CO 3的量改变为0.38mol，将0.001mol的Mo(SO 4) 3换成0.12mol的MgSO 4之外，其他与制备例1相同。
对比例6
除了将MnSO 4﹒H 2O的量改为0.8mol，0.7mol的FeSO 4﹒H 2O换成1.2mol的ZnSO 4，将Li 2CO 3的量改变为0.499mol，将0.001mol的Mo(SO 4) 3换成0.001mol的MgSO 4之外，其他与制备例1相同。
对比例7
除了将MnSO 4﹒H 2O的量改为1.4mol，FeSO 4﹒H 2O的量改为0.6mol，将Li 2CO 3的量改变为0.534mol，将0.001mol的Mo(SO 4) 3换成0.001mol的MgSO 4，将磷酸的量改成0.88mol，H 4SiO 4的量改成0.12mol，NH 4HF 2的量改成0.025mol之外，其他与制备例1相同。
对比例8
除了将MnSO 4﹒H 2O的量改为1.2mol，FeSO 4﹒H 2O的量改为0.8mol，将Li 2CO 3的量改变为0.474mol，将0.001mol的Mo(SO 4) 3换成0.001mol的MgSO 4，将磷酸的量改成0.93mol，H 4SiO 4的量改成 0.07mol，NH 4HF 2的量改成0.06mol之外，其他与制备例1相同。
将正极活性材料、粘结剂PVDF和导电剂超导炭黑(Super-P)按照97％:1.5％:1.5％的质量比混合，然后分散于N-甲基吡咯烷酮溶剂中，得到固含量为60％w/w的正极活性材料的浆料。
正极极片的制备
实施例1
将制备例1正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，在100～120℃的高温下真空干燥14h，辊压机压实，得到正极极片P1。
实施例2
将制备例55正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，在100～120℃的高温下真空干燥14h，辊压机压实，得到正极极片P2。
实施例3
将制备例1正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂布在铝箔的一面上，将制备例55正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂布在铝箔的另一面上，在100～120℃的高温下真空干燥14h，辊压机压实，得到正极极片P3。
实施例4
将制备例56正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例3相同，得到正极极片P4。
实施例5
将制备例1正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂布在铝箔的一面上，将制备例56正极活性材料的浆料以0.019g/cm 2的 涂布量均匀涂布在铝箔的另一面上，其他与实施例3相同，得到正极极片P5。
实施例6
将制备例55正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂布在铝箔的一面上，将制备例56正极活性材料以0.019g/cm 2的涂布量的浆料均匀涂布在铝箔的另一面上，其他与实施例3相同，得到正极极片P6。
实施例7
在铝箔的两面均依次涂布制备例1正极活性材料的浆料和制备例55正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，然后，在100～120℃高温真空干燥14h，辊压机压实，得到正极极片P7。
实施例8
在铝箔的两面均依次涂布制备例55正极活性材料的浆料和制备例1正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，其他与实施例7相同，得到正极极片P8。
实施例9
在铝箔的两面均依次涂布制备例1正极活性材料的浆料和制备例56正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，其他与实施例7相同，得到正极极片P9。
实施例10
在铝箔的两面均依次涂布制备例56正极活性材料的浆料和制备例1正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，其他与实施例7相同，得到正极极片P10。
实施例11
在铝箔的两面均依次涂布制备例55正极活性材料的浆料和制备例56正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，其他与实施例7相同，得到正极极片P11。
实施例12
在铝箔的两面均依次涂布制备例56正极活性材料的浆料和制备例55正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，其他与实施例7相同，得到正极极片P12。
实施例13
在铝箔的A面均依次涂布制备例1正极活性材料的浆料和制备例55正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例1正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，然后，在100～120℃高温真空干燥14h，辊压机压实，得到正极极片P13。
实施例14
在铝箔的A面均依次涂布制备例1正极活性材料的浆料和制备例55正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例55正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P14。
实施例15
在铝箔的A面均依次涂布制备例1正极活性材料的浆料和制备例55正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例56正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P15。
实施例16
在铝箔的A面均依次涂布制备例55正极活性材料的浆料和制备例1正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例1正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P16。
实施例17
在铝箔的A面均依次涂布制备例55正极活性材料的浆料和制备例1正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例55正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P17。
实施例18
在铝箔的A面均依次涂布制备例55正极活性材料的浆料和制备例1正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例56正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P18。
实施例19
在铝箔的A面均依次涂布制备例1正极活性材料的浆料和制备例56正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例1正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P19。
实施例20
在铝箔的A面均依次涂布制备例1正极活性材料的浆料和制备例56正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例55正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P20。
实施例21
在铝箔的A面均依次涂布制备例1正极活性材料的浆料和制备例56正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例56正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P21。
实施例22
在铝箔的A面均依次涂布制备例56正极活性材料的浆料和制备例1正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例1正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P22。
实施例23
在铝箔的A面均依次涂布制备例56正极活性材料的浆料和制备例1正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例55正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P23。
实施例24
在铝箔的A面均依次涂布制备例56正极活性材料的浆料和制备例1正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例56正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P24。
实施例25
在铝箔的A面均依次涂布制备例55正极活性材料的浆料和制备例56正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例1正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P25。
实施例26
在铝箔的A面均依次涂布制备例55正极活性材料的浆料和制备例56正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例55正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P26。
实施例27
在铝箔的A面均依次涂布制备例55正极活性材料的浆料和制备例56正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例56正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P27。
实施例28
在铝箔的A面均依次涂布制备例56正极活性材料的浆料和制备例55正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例1正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P28。
实施例29
在铝箔的A面均依次涂布制备例56正极活性材料的浆料和制备例55正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例55正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P29。
实施例30
在铝箔的A面均依次涂布制备例56正极活性材料的浆料和制备例55正极活性材料的浆料，每层浆料的涂布量均为0.010g/cm 2，在铝箔的B面均匀涂布制备例56正极活性材料的浆料，浆料的涂布量为0.020g/cm 2，其他与实施例13相同，得到正极极片P30。
实施例31
将制备例57正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，在100～120℃的高温下真空干燥14h，辊压机压实，得到正极极片P31。
实施例32
将制备例58正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，在100～120℃的高温下真空干燥14h，辊压机压实，得到正极极片P32。
实施例33
将制备例59正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，在100～120℃的高温下真空干燥14h，辊压机压实，得到正极极片P33。
实施例34
将制备例60正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，在100～120℃的高温下真空干燥14h，辊压机压实，得到正极极片P34。
实施例35
将制备例61正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，在100～120℃的高温下真空干燥14h，辊压机压实，得到正极极片P35。
实施例36
将制备例62正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，在100～120℃的高温下真空干燥14h，辊压机压实，得到正极极片P36。
实施例37
将制备例63正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，在100～120℃的高温下真空干燥14h，辊压机压实，得到正极极片P37。
实施例38
将制备例64正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例37相同，得到正极极片P38。
实施例39
将制备例65正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例37相同，得到正极极片P39。
实施例40
将制备例66正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例37相同，得到正极极片P40。
实施例41
将制备例67正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例37相同，得到正极极片P41。
实施例42
将制备例68正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例37相同，得到正极极片P42。
实施例43
将制备例69正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例37相同，得到正极极片P3。
实施例44
将制备例70正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂 在集流体铝箔的两面，其他与实施例37相同，得到正极极片P44。
实施例45
将制备例71正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例37相同，得到正极极片P45。
实施例46
将制备例72正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例37相同，得到正极极片P46。
实施例47
将制备例73正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例37相同，得到正极极片P47。
实施例48
将制备例74正极活性材料的浆料以0.019g/cm 2的涂布量均匀涂在集流体铝箔的两面，其他与实施例37相同，得到正极极片P48。
以上各正极极片的参数见表4。
表4正极极片参数
Figure PCTCN2022084258-appb-000006
Figure PCTCN2022084258-appb-000007
Figure PCTCN2022084258-appb-000008
Figure PCTCN2022084258-appb-000009
Figure PCTCN2022084258-appb-000010
“*”：第1层指与铝箔表面接触的一层，第2层指设置在第1层上的一层。
“#”：第一正极活性材料指制备例1制得的正极活性材料，第二正极活性材料指制备例55、制备例57、制备例59-66的正极活性材料。
负极极片的制备
将负极活性材料人造石墨、导电剂超导炭黑(Super-P)、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC-Na)按照质量比为95％：1.5％：1.8％：1.7％溶于去离子水中，充分搅拌混合均匀后，得到粘度3000mPa.s、固含52％的负极浆料；将负极浆料涂覆在6μm的负极集流体铜箔上，之后在100℃烘烤4小时以烘干，辊压，得到压实密度为1.75g/cm3的负极极片。
隔离膜
采用聚丙烯膜。
电解液的制备
将碳酸乙烯酯、碳酸二甲酯和1,2-丙二醇碳酸酯按体积比1:1:1混合，然后将LiPF 6均匀溶解在上述溶液中，得到电解液。该电解液中，LiPF 6的浓度为1mol/L。
全电池的制备
采用上述的正极极片，按照负极极片、隔膜、正极极片的顺序，采用卷绕法形成裸电芯，分别冲切出铝极耳和铜极耳，得到裸电芯；通过转接片将两个裸电芯铜与铜极耳，铝与铝极耳一起焊接到电池顶盖上，对裸电芯进行包裹绝缘后，将裸电芯装入铝壳中，将顶盖与铝壳焊接形成干电芯，对干电芯进行烘烤除水后注入电解液，对电池进 行化成和老化，相应地得到全电池。其中，正极极片P1、P2、P3、P8、P10、P11、P12、P17、P18、P23、P24、P26、P27所制的电池结构如图7-19所示。
扣式电池的制备
将上述的正极极片与负极、电解液一起在扣电箱中组装成扣式电池(下文也称“扣电”)。
Ⅰ.正极活性材料的性质测试
1.正极活性材料化学式的测定
采用球差电镜仪(ACSTEM)对正极活性材料内部微观结构和表面结构进行高空间分辨率表征，结合三维重构技术得到正极活性材料的化学式。
2.晶格变化率测量方法
在25℃恒温环境下，将正极活性材料样品置于XRD(型号为Bruker D8 Discover)中，采用1°/min对样品进行测试，并对测试数据进行整理分析，参照标准PDF卡片，计算出此时的晶格常数a0、b0、c0和v0(a0,b0和c0表示晶胞各个方面上的长度大小，v0表示晶胞体积，可通过XRD精修结果直接获取)。
将正极活性材料样品按照制备正极极片P1的方法制成正极极片，然后按照上述“扣式电池的制备”制备成扣电，并对上述扣电以0.05C小倍率进行充电，直至电流减小至0.01C。然后将扣电中的正极极片取出，并置于DMC中浸泡8小时。然后烘干，刮粉，并筛选出其中粒径小于500nm的颗粒。取样并按照与上述测试新鲜样品同样的方式计算出其晶格常数v1，将(v0-v1)/v0×100％作为其完全脱嵌锂前后的晶格变化率示于表中。
3.Li/Mn反位缺陷浓度测量方法
将“晶格变化率测量方法”中测试的XRD结果与标准晶体的PDF (Powder Diffraction File)卡片对比，得出Li/Mn反位缺陷浓度。具体而言，将“晶格变化率测量方法”中测试的XRD结果导入通用结构分析系统(GSAS)软件中，自动获得精修结果，其中包含了不同原子的占位情况，通过读取精修结果获得Li/Mn反位缺陷浓度。
4.表面氧价态测量方法
取5g正极活性材料样品按照上述制备正极极片P1的方法制成正极极片，然后按照上述“扣式电池的制备”制备成扣电。对扣电采用0.05C小倍率进行充电，直至电流减小至0.01C。然后将扣电中的正极极片取出，并置于DMC中浸泡8小时。然后烘干，刮粉，并筛选出其中粒径小于500nm的颗粒。将所得颗粒用电子能量损失谱(EELS，所用仪器型号为Talos F200S)进行测量，获取能量损失近边结构(ELNES)，其反映元素的态密度和能级分布情况。根据态密度和能级分布，通过对价带态密度数据进行积分，算出占据的电子数，从而推算出充电后的表面氧的价态。
5.压实密度测量方法
取5g正极活性材料的粉末放于压实专用模具(美国CARVER模具，型号13mm)中，然后将模具放在压实密度仪器上。施加3T的压力，在设备上读出压力下粉末的厚度(卸压后的厚度)，通过ρ＝m/v，计算出压实密度。
6.循环后Mn(以及Mn位掺杂的Fe)溶出量测量方法
将正极活性材料样品按照上述制备正极极片P1的方法制成正极极片，然后按照上述“全电池的制备”制备成全电池。
采用将45℃下循环至容量衰减至80％后的全电池采用0.1C倍率进行放电至截止电压2.0V。然后将电池拆开，取出负极极片，在负极极片上随机取30个单位面积(1540.25mm 2)的圆片，用Agilent ICP-OES730测试电感耦合等离子体发射光谱(ICP)。根据ICP结果计算其中Fe(如果正极活性材料的Mn位掺杂有Fe的话)和Mn的 量，从而计算循环后Mn(以及Mn位掺杂的Fe)的溶出量。测试标准依据EPA-6010D-2014。
7.扣式电池初始克容量测量方法
在2.5～4.3V下，将扣式电池按照0.1C充电至4.3V，然后在4.3V下恒压充电至电流小于等于0.05mA，静置5min，然后按照0.1C放电至2.0V，此时的放电容量为初始克容量，记为D0。
8. 3C充电恒流比测量方法
在25℃恒温环境下，将新鲜全电池静置5min，按照1/3C放电至2.5V。静置5min，按照1/3C充电至4.3V，然后在4.3V下恒压充电至电流小于等于0.05mA。静置5min，记录此时的充电容量为C0。按照1/3C放电至2.5V，静置5min，再按照3C充电至4.3V，静置5min，记录此时的充电容量为C1。3C充电恒流比即为C1/C0×100％。
3C充电恒流比越高，说明电池的倍率性能越好。
9.全电池45℃循环性能测试
在45℃的恒温环境下，在2.5～4.3V下，将全电池按照1C充电至4.3V，然后在4.3V下恒压充电至电流小于等于0.05mA。静置5min，然后按照1C放电至2.5V，记录此时的放电容量为D0。重复前述充放电循环，直至放电容量降低到D0的80％。记录此时电池经过的循环圈数。
10.全电池60℃胀气测试
在60℃下，存储100％充电状态(SOC)的全电池。在存储前后及过程中测量电芯的开路电压(OCV)和交流内阻(IMP)以监控SOC，并测量电芯的体积。其中在每存储48h后取出全电池，静置1h后测试开路电压(OCV)、内阻(IMP)，并在冷却至室温后用排水法测量电芯体积。排水法即先用表盘数据自动进行单位转换的天平单独测量电芯的重力F 1，然后将电芯完全置于去离子水(密度已知为 1g/cm 3)中，测量此时的电芯的重力F 2，电芯受到的浮力F 浮即为F 1-F 2，然后根据阿基米德原理F 浮＝ρ×g×V 排，计算得到电芯体积V＝(F 1-F 2)/(ρ×g)。
由OCV、IMP测试结果来看，本实验过程中直至存储结束，实施例的电池始终保持99％以上的SOC。
存储30天后，测量电芯体积，并计算相对于存储前的电芯体积，存储后的电芯体积增加的百分比。
另外，测量电芯残余容量。在2.5～4.3V下，将全电池按照1C充电至4.3V，然后在4.3V下恒压充电至电流小于等于0.05mA。静置5min，记录此时的充电容量为电芯残余容量。
表5中示出制备例1-11和对比例1-8的正极活性材料组成。表6中示出制备例1-11和对比例1-8的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据。表7示出制备例12-27的正极活性材料组成。表8中示出制备例12-27的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据。表9中示出制备例28-41的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据。表10中示出制备例42-54的正极活性材料或扣电或全电按照上述性能测试方法测得性能数据。
表5制备例1-11及对比例1-8正极活性材料的化学式
  化学式
制备例1 Li 0.994Mo 0.001Mn 0.65Fe 0.35P 0.999Si 0.001O 3.999F 0.001
制备例2 Li 0.977Mg 0.001Mn 0.65Fe 0.34Ti 0.01P 0.999N 0.001O 3.999F 0.001
制备例3 Li 0.992W 0.001Mn 0.65Fe 0.35P 0.999S 0.001O 3.999F 0.001
制备例4 Li 0.997Al 0.001Mn 0.65Fe 0.35P 0.999Si 0.001O 3.999Cl 0.001
制备例5 Li 0.993Nb 0.001Mn 0.65Fe 0.345V 0.005P 0.999S 0.001O 3.999F 0.001
制备例6 Li 0.993Nb 0.001Mn 0.65Fe 0.34V 0.005Mg 0.005P 0.999S 0.001O 3.999F 0.001
制备例7 Li 0.993Nb 0.001Mn 0.65Fe 0.34V 0.005Co 0.005P 0.999S 0.001O 3.999F 0.001
制备例8 Li 0.993Nb 0.001Mn 0.65Fe 0.34V 0.005Ni 0.005P 0.999S 0.001O 3.999F 0.001
制备例9 Li 0.991Nb 0.001Mn 0.65Fe 0.349Ti 0.001P 0.999S 0.001O 3.999Cl 0.001
制备例10 Li 0.995Nb 0.001Mn 0.65Fe 0.34V 0.005Mg 0.005P 0.999Si 0.001O 3.999Br 0.001
制备例11 Li 0.998Mg 0.001Mn 0.65Fe 0.345V 0.005P 0.999Si 0.001O 3.999Br 0.001
对比例1 LiMnPO 4
对比例2 LiMn 0.85Fe 0.15PO 4
对比例3 Li 0.990Mg 0.005Mn 0.95Zn 0.05PO 4
对比例4 Li 0.90Nb 0.01Mn 0.6Fe 0.4PO 3.95F 0.05
对比例5 Li 0.76Mg 0.12Mn 0.7Fe 0.3P 0.999Si 0.001O 3.999F 0.001
对比例6 Li 0.998Mg 0.001Mn 0.4Zn 0.6P 0.999Si 0.001O 3.999F 0.001
对比例7 Li 1.068Mg 0.001Mn 0.7Fe 0.3P 0.88Si 0.12O 3.95F 0.05
对比例8 Li 0.948Mg 0.001Mn 0.6Fe 0.4P 0.93Si 0.07O 3.88F 0.12
表6制备例1-11和对比例1-8的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据
Figure PCTCN2022084258-appb-000011
Figure PCTCN2022084258-appb-000012
表7制备例12-27正极活性材料的化学式及元素比
  化学式 (1-y):y a：x
制备例12 Li 0.997Mg 0.001Mn 0.68Fe 0.3V 0.02P 0.999N 0.001O 3.999F 0.001 2.13 997
制备例13 Li 0.997Mg 0.001Mn 0.58Fe 0.4V 0.02P 0.999N 0.001O 3.999F 0.001 1.38 997
制备例14 Li 0.997Mg 0.001Mn 0.65Fe 0.3V 0.05P 0.999N 0.001O 3.999F 0.001 1.86 997
制备例15 Li 0.988Mg 0.005Mn 0.6Fe 0.35V 0.05P 0.999S 0.001O 3.999F 0.001 1.50 197.6
制备例16 Li 0.984Mg 0.005Mn 0.6Fe 0.35V 0.05P 0.995S 0.005O 3.999F 0.001 1.50 196.8
制备例17 Li 0.984Mg 0.005Mn 0.6Fe 0.35V 0.05P 0.999S 0.001O 3.995F 0.005 1.50 196.8
制备例18 Li 0.984Mg 0.005Mn 0.65Fe 0.25V 0.05Co 0.05P 0.999S 0.001O 3.995F 0.005 1.86 196.8
制备例19 Li 0.984Mg 0.005Mn 0.65Fe 0.20V 0.05Co 0.10P 0.999S 0.001O 3.995F 0.005 1.86 196.8
制备例20 Li 0.984Mg 0.005Mn 0.75Fe 0.05V 0.05Co 0.15P 0.999S 0.001O 3.995F 0.005 3.00 196.8
制备例21 Li 0.984Mg 0.005Mn 0.65Fe 0.25V 0.05Ni 0.05P 0.999S 0.001O 3.995F 0.005 1.86 196.8
制备例22 Li 0.984Mg 0.005Mn 0.75Fe 0.10V 0.05Ni 0.10P 0.999S 0.001O 3.995F 0.005 3.00 196.8
制备例23 Li 0.984Mg 0.005Mn 0.7Fe 0.15V 0.05Co 0.10P 0.999S 0.001O 3.995F 0.005 2.33 196.8
制备例24 Li 0.984Mg 0.005Mn 0.6Fe 0.25V 0.05Co 0.10P 0.999S 0.001O 3.995F 0.005 1.50 196.8
制备例25 Li 0.984Mg 0.005Mn 0.5Fe 0.35V 0.05Co 0.10P 0.999S 0.001O 3.995F 0.005 1.00 196.8
制备例26 Li 1.01Mg 0.005Mn 0.7Fe 0.15V 0.05Co 0.10P 0.9Si 0.1O 3.92F 0.08 2.33 202
制备例27 Li 0.97Mg 0.005Mn 0.7Fe 0.15V 0.05Co 0.10P 0.92Si 0.08O 3.9F 0.1 2.33 194
表8制备例12-27的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据
Figure PCTCN2022084258-appb-000013
Figure PCTCN2022084258-appb-000014
表9制备例28-41的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据
Figure PCTCN2022084258-appb-000015
Figure PCTCN2022084258-appb-000016
表10制备例42-54的正极活性材料或扣电或全电按照上述性能测试方法测得的性能数据
Figure PCTCN2022084258-appb-000017
Figure PCTCN2022084258-appb-000018
由上述表6、8、9、10可见，本申请制备例的各正极活性材料均在循环性能、高温稳定性、克容量和压实密度中的一个甚至全部方面实现了比对比例更优的效果。
由制备例18-20、23-25之间相比，可以看出，在其他元素相同的情况下，(1-y):y在1至4范围内，能够进一步提升二次电池的能量密度和循环性能。
Ⅱ.电池测试
采用正极极片P2-P48制备的二次电池进行如下测试：
(1)按照国标GB 38031-2020“电动汽车用动力蓄电池安全要求”中的方法测定二次电池的能量密度；
(2)按照国标GBT31486-2015“电动汽车用动力蓄电池电性能要求及试验方法”测定二次电池的-20℃低温放电容量保持率(充放电循环两次)，以获取电池的动力学数据；
(3)按照国标GBT31484-2015“电动汽车用动力蓄电池循环寿命要求及试验方法”中的标准循环测试方法测试二次电池80％SOH的常温循环寿命；
(4)参考国标GBT31484-2015“电动汽车用动力蓄电池循环寿命要求及试验方法”中的标准循环测试方法，将测试过程温度调整为-10℃，充放电电流调整为0.33C，其余条件不变，测试二次电池80％SOH的低温循环寿命；
(5)参考国标GBT31486-2015“电动汽车用动力蓄电池电性能要 求及试验方法”测定二次电池20％SOC的比功率数据，详细步骤如下：
a)以国标GBT31486-2015中6.3.4方法充电；
b)室温下，二次电池以1C电流放电48min后按照规定的最大放电电流放电10s，然后再静置30min，再以规定的最大充电电流充电10s；
c)采用10s充放电的放电能量除以10s充放电时间的方法，以此计算电芯的比功率(W/kg)。
上述结果见表11。
表11电池测试的结果
Figure PCTCN2022084258-appb-000019
Figure PCTCN2022084258-appb-000020
根据上述结果可知：
与采用正极极片P2的二次电池相比，采用正极极片P3-P30的二次电池的能量密度更高、低温放电容量保持率更高、比功率更高、低温循环寿命更长，采用正极极片P3-P5、P7、P9-P12、P14-15、P17-18、P20、P22、P24、P26-P30的二次电池的常温循环寿命更长；
与采用正极极片P31的二次电池相比，采用正极极片P32的二次电池的能量密度更高、低温放电容量保持率更高、比功率更高、低温循环寿命更长；
正极极片P41-P48包含第一正极活性材料和第二正极活性材料，正极极片P33-P40仅包含等量的与之对应的第二正极活性材料，与仅包含第二正极活性材料的正极极片相比，包含第一正极活性材料和第二正极活性材料的正极极片所制二次电池的能量密度更高、低温放电容量保持率更高、比功率更高、低温循环寿命更长；
以上说明，本申请正极极片所制二次电池的能量密度更高，动力学性能更好，电芯倍率性能更高，低温循环寿命更长，低温循环容量保持率更高，同时安全性更高。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (17)

  1. 一种正极极片，包括正极集流体和设置在所述正极集流体的至少一个表面上的正极膜层；所述正极膜层为单层结构或多层结构；当所述正极膜层为单层结构时，至少一个所述正极膜层同时包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料和第二正极活性材料；和/或，当所述正极膜层为多层结构时，至少一个所述正极膜层的至少一层中同时包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料和第二正极活性材料；
    其中，
    所述A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素；
    所述R包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素；
    所述C包括选自B、S、Si和N中的一种或多种元素；
    所述D包括选自S、F、Cl和Br中的一种或多种元素；
    所述a选自0.9至1.1的范围，所述x选自0.001至0.1的范围，所述y选自0.001至0.5的范围，所述z选自0.001至0.1的范围，所述n选自0.001至0.1的范围；
    所述第二正极活性材料为选自LiFePO 4、碳包覆LiFePO 4、LiFe bM cPO 4和碳包覆LiFe bM cPO 4中的一种或多种，其中，所述M独立地包括选自Ti、Zn、Co、Mn、La、V、Mg、Al、Nb、W、Zr、Nb、Sm、Cr、Cu和B中的一种或多种元素，所述b独立地选自0.99至0.999的范围且b+c＝1。
  2. 一种正极极片，包括正极集流体和设置在所述正极集流体的至少一个表面上的正极膜层；至少一个所述正极膜层为多层结构，任一具有多层结构的所述正极膜层在不同层中分别包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料和第二正极活性材料；
    其中，
    所述A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素，
    所述R包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素，
    所述C包括选自B、S、Si和N中的一种或多种元素，
    所述D包括选自S、F、Cl和Br中的一种或多种元素，
    所述a选自0.9至1.1的范围，所述x选自0.001至0.1的范围，所述y选自0.001至0.5的范围，所述z选自0.001至0.1的范围，所述n选自0.001至0.1的范围；
    所述第二正极活性材料为选自LiFePO 4、碳包覆LiFePO 4、LiFe bM cPO 4和碳包覆LiFe bM cPO 4中的一种或多种，其中，所述M独立地包括选自Ti、Zn、Co、Mn、La、V、Mg、Al、Nb、W、Zr、Nb、Sm、Cr、Cu和B中的一种或多种元素，所述b独立地选自0.99至0.999的范围且b+c＝1；
    可选地，任一具有多层结构的所述正极膜层在相邻层中分别包含所述第一正极活性材料和所述第二正极活性材料。
  3. 一种正极极片，包括正极集流体和分别设置在所述正极集流体的两个表面上的正极膜层A和正极膜层B；所述正极膜层A和所述正极膜层B独立地为单层结构或多层结构；所述正极膜层A的至少一层中包含化学式为Li aA xMn 1-yR yP 1-zC zO 4-nD n的第一正极活性材料，同时，所述正极膜层B的至少一层中包含第二正极活性材料；
    其中，
    所述A包括选自Zn、Al、Na、K、Mg、Nb、Mo和W中的一种或多种元素，
    所述R包括选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的一种或多种元素，
    所述C包括选自B、S、Si和N中的一种或多种元素，
    所述D包括选自S、F、Cl和Br中的一种或多种元素，
    所述a选自0.9至1.1的范围，所述x选自0.001至0.1的范围， 所述y选自0.001至0.5的范围，所述z选自0.001至0.1的范围，所述n选自0.001至0.1的范围；
    所述第二正极活性材料为选自LiFePO 4、碳包覆LiFePO 4、LiFe bM cPO 4和碳包覆LiFe bM cPO 4中的一种或多种，其中，所述M独立地包括选自Ti、Zn、Co、Mn、La、V、Mg、Al、Nb、W、Zr、Nb、Sm、Cr、Cu和B中的一种或多种元素，所述b独立地选自0.99至0.999的范围且b+c＝1。
  4. 根据权利要求1至3中任一项所述的正极极片，其中，所述第二正极活性材料中，
    碳质量占所述碳包覆LiFePO 4的质量的0.1％-4％；和/或，
    碳质量占所述碳包覆LiFe bM cPO 4的质量的0.1％-4％。
  5. 根据权利要求1至4中任一项所述的正极极片，其中，所述第一正极活性材料与所述第二正极活性材料的质量比为1:7-7:1，可选为1:4-4:1。
  6. 根据权利要求1至5中任一项所述的正极极片，其中，所述第一正极活性材料中，
    所述R为选自Ti、V、Zr、Fe、Ni、Mg、Co、Ga、Sn、Sb、Nb和Ge中的至少两种元素；和/或，
    所述A为选自Mg和Nb中的任一种元素，和/或，
    所述R为选自Fe、Ti、V、Co和Mg中的至少两种元素，可选地为Fe与选自Ti、V、Co和Mg中的一种以上元素，和/或，
    所述C为S，和/或，
    所述D为F。
  7. 根据权利要求1至6中任一项所述的正极极片，其中，所述第一正极活性材料中，
    所述x选自0.001-0.005的范围；和/或，
    所述y选自0.01至0.5的范围，可选地选自0.25至0.5的范围；和/或，
    所述z选自0.001至0.005的范围；和/或，
    所述n选自0.001至0.005的范围；和/或，
    所述(1-y)与y的比值选自1-4的范围，可选为选自1.5-3的范围；和/或，
    所述a与x的比值选自9-1100的范围，可选为选自190-998的范围。
  8. 根据权利要求1至7中任一项所述的正极极片，其中，所述第一正极活性材料的晶格变化率为8％以下，可选地为4％以下。
  9. 根据权利要求1至8中任一项所述的正极极片，其中，所述第一正极活性材料的Li/Mn反位缺陷浓度为2％以下，可选地为0.5％以下。
  10. 根据权利要求1至9中任一项所述的正极极片，其中，所述第一正极活性材料的表面氧价态为-1.82以下，可选地为-1.89～-1.98。
  11. 根据权利要求1至10中任一项所述的正极极片，其中，所述第一正极活性材料在3T下的压实密度为2.0g/cm 3以上，可选地为2.2g/cm 3以上。
  12. 根据权利要求1至11中任一项所述的正极极片，其中，所述第一正极活性材料的表面还包覆有碳。
  13. 根据权利要求1至12中任一项所述的正极极片，其中，所述第一正极活性材料和所述第二正极活性材料的质量之和占所述正极极片的质量的88％-98.7％。
  14. 一种二次电池，包括权利要求1至13中任一项所述的正极极片。
  15. 一种电池模块，包括权利要求14所述的二次电池。
  16. 一种电池包，包括权利要求15所述的电池模块。
  17. 一种用电装置，包括选自权利要求14所述的二次电池、权利要求15所述的电池模块和权利要求16所述的电池包中的至少一种。
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