WO2023046066A1 - 电池正极材料及其应用 - Google Patents

电池正极材料及其应用 Download PDF

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WO2023046066A1
WO2023046066A1 PCT/CN2022/120833 CN2022120833W WO2023046066A1 WO 2023046066 A1 WO2023046066 A1 WO 2023046066A1 CN 2022120833 W CN2022120833 W CN 2022120833W WO 2023046066 A1 WO2023046066 A1 WO 2023046066A1
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particles
lithium
positive electrode
battery
electrode material
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PCT/CN2022/120833
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English (en)
French (fr)
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程斌
潘仪
庄明昊
邓若燚
吴鹏宇
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比亚迪股份有限公司
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Priority to EP22872110.6A priority Critical patent/EP4345950A1/en
Priority to CA3224474A priority patent/CA3224474A1/en
Priority to KR1020247000233A priority patent/KR20240017066A/ko
Priority to AU2022350974A priority patent/AU2022350974A1/en
Publication of WO2023046066A1 publication Critical patent/WO2023046066A1/zh
Priority to US18/404,671 priority patent/US20240145715A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • 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
    • 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
    • H01M4/52—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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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 field of secondary batteries, in particular to a battery cathode material and its application.
  • the battery compaction density and energy density of some phosphate systems are low, which is not conducive to the application of batteries. Therefore, it is necessary to provide a battery cathode material so that the pole piece has a higher compaction density, so that the battery can take into account high energy density, high cycle stability and safety.
  • the first aspect of the present application provides a battery positive electrode material
  • the battery positive electrode material includes lithium manganese iron phosphate particles and active particles filled in the gaps between the lithium manganese iron phosphate particles;
  • the active particles include nickel cobalt lithium manganese oxide One or more of particles, nickel-cobalt lithium aluminate particles, lithium-rich manganese-based material particles, lithium cobaltate particles, spinel lithium manganate LiMn2O4 particles and layered lithium manganate LiMnO2 particles ;
  • the ratio of the median diameter of the lithium manganese iron phosphate to the active particles is 3-8; in the positive electrode material of the battery, the mass percentage of the lithium manganese iron phosphate is 70%-90%, and the active The mass percentage of the particles is 10%-30%.
  • the median particle size of the lithium manganese iron phosphate particles is 2 ⁇ m-15 ⁇ m.
  • the median diameter of the active particles is 0.5 ⁇ m-5 ⁇ m.
  • the active particles include primary active particles and secondary active particles, the median diameter of the primary active particles is 0.5 ⁇ m-5 ⁇ m, and the median diameter of the secondary active particles is The diameter is 0.1 ⁇ m-2 ⁇ m.
  • the mass ratio of the lithium manganese iron phosphate particles to the active particles is 1:(0.2 ⁇ 0.35).
  • the lithium manganese iron phosphate particles include LiMn x Fe 1-x PO 4 , where 0.5 ⁇ x ⁇ 0.9.
  • the lithium iron manganese phosphate particles include carbon, and the carbon accounts for 1% to 3% by mass of the lithium iron manganese phosphate particles.
  • the lithium manganese iron phosphate particles further include doping elements, and the doping elements include Ti, V, Co, Ni, Cu, Zn, Mg, Ca, Al, Nb, Mo one or more.
  • the lithium nickel cobalt manganese oxide particles include LiNia Co b Mn 1-ab O 2 , wherein 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ 1-ab ⁇ 1.
  • the nickel-cobalt lithium manganese oxide particles further include a doping element, and the doping element includes one of Ti, V, Fe, Cu, Zn, Mg, Ca, Al, Nb, Mo one or more species.
  • the lithium nickel cobalt aluminate particles include LiNim Co n Al 1-mn O 2 , wherein 0 ⁇ m ⁇ 1, 0 ⁇ n ⁇ 1, 0 ⁇ 1-mn ⁇ 1.
  • the lithium nickel cobalt aluminate particles further include a doping element, and the doping element includes one of Ti, V, Mn, Fe, Cu, Zn, Mg, Ca, Nb, Mo one or more species.
  • the lithium-rich manganese-based material particles include yLi 2 MnO 3 ⁇ (1-y)LiMO 2 , where 0 ⁇ y ⁇ 1, and M includes at least one of Mn, Ni or Co kind.
  • the lithium-rich manganese-based material particles further include a doping element, and the doping element includes one of Ti, V, Fe, Co, Cu, Zn, Mg, Ca, Nb, and Mo. one or more species.
  • the compacted density of the positive electrode material of the battery is 2.4g/cm 3 -3.2g/cm 3 .
  • the active particles are not attached to the particle surface of the lithium manganese iron phosphate particles in a coated form.
  • the active particles have a higher compaction density than the lithium iron manganese phosphate particles.
  • the second aspect of the present application provides a positive electrode sheet, including a current collector and a positive electrode material layer disposed on the current collector, and the positive electrode material layer includes the battery positive electrode material as described in the first aspect.
  • the third aspect of the present application provides a secondary battery, including a positive electrode, a negative electrode, a separator and an electrolyte, and the positive electrode includes the positive electrode sheet as described in the second aspect.
  • Fig. 1 is a schematic structural diagram of a battery anode material provided by an embodiment of the present application
  • Figure 2 is a schematic structural view of a positive electrode material provided by the present application.
  • FIG. 3 is a schematic structural view of a battery positive electrode material provided by an embodiment of the present application.
  • FIG. 4 is a scanning electron microscope image of the battery cathode material provided in Example 1 of the present application.
  • the schematic diagram of the battery cathode material structure shows the particle distribution in the two-dimensional direction, but it should actually be a three-dimensional stereogram.
  • Li iron phosphate cathode materials represented by lithium iron phosphate have the advantages of long cycle life, high safety, environmental friendliness, and low cost, and occupy an important position in the cathode material system of lithium-ion batteries.
  • lithium manganese iron phosphate has a higher theoretical energy density.
  • the electron and ion transmission rate of lithium iron manganese phosphate is lower, which limits its capacity.
  • FIG. 1 is a schematic structural diagram of a battery positive electrode material provided by an embodiment of the present application. Please refer to FIG. 1 .
  • the battery positive electrode material 10 of the present application includes lithium manganese iron phosphate particles 11 and active particles 12 dispersed in the gaps between the lithium manganese iron phosphate particles.
  • the active particles and lithium manganese iron phosphate particles are a physically blended system, and the active particles with smaller particle sizes are filled in the gaps between the lithium manganese iron phosphate particles. It should be noted that in the battery positive electrode material of this application, There is no agglomeration among the particles, and the small-sized particles do not adhere to the surface of the large-sized particles in the form of coating, but accumulate with the large particles in a single dispersed state to form a physical blending system.
  • the lithium manganese iron phosphate particles have a larger particle size, and the active particles with smaller particle sizes can be filled in the gaps of the lithium manganese iron phosphate particles.
  • the active particles Compared with the lithium manganese iron phosphate particles, the active particles have Higher compaction density, thus significantly improving the overall compaction density of the material without changing the overall volume of the material, so that the positive electrode material of the battery has a higher volumetric energy density; and the mass specific capacity and voltage of the active particles are also high
  • the active particles have good low-temperature performance, which is conducive to improving the low-temperature performance of the battery cathode material.
  • lithium manganese iron phosphate includes LiMn x Fe 1-x PO 4 , where 0.5 ⁇ x ⁇ 0.9.
  • element doping can be performed on lithium manganese iron phosphate to improve the Conductivity, the doping element can be one or more of Ti, V, Co, Ni, Cu, Zn, Mg, Ca, Al, Nb, Mo, for example. The doping element accounts for 0.2%-2% by mass of all transition metal elements in the lithium iron manganese phosphate.
  • the lithium manganese iron phosphate also includes carbon with a mass percentage of 1% to 3%, and a certain amount of carbon is beneficial to improve the conductivity of the positive electrode material of the battery.
  • the active particles include one or more of nickel-cobalt lithium manganese oxide particles, nickel-cobalt lithium aluminate particles, lithium-rich manganese-based material particles, lithium cobalt oxide particles, and lithium manganese oxide particles.
  • the lithium nickel cobalt manganese oxide particles include LiNi a Co b Mn 1-ab O 2 , where 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ 1-ab ⁇ 1; nickel cobalt aluminum acid
  • the lithium particles include LiNim Co n Al 1-mn O 2 , wherein, 0 ⁇ m ⁇ 1, 0 ⁇ n ⁇ 1, 0 ⁇ 1-mn ⁇ 1;
  • the lithium-rich manganese-based material particles include yLi 2 MnO 3 ⁇ (1 -y) LiMO 2 , wherein, 0 ⁇ y ⁇ 1, M includes at least one of Mn, Ni or Co;
  • the chemical formula of lithium cobaltate particles is LiCoO 2 ;
  • the lithium manganate particles include spinel lithium manganese oxide LiMn 2 O 4 or one or more of layered lithium manganate LiMnO 2 .
  • active particles can not only increase the energy density of the positive electrode material of the battery, but also effectively improve the low-temperature performance of the battery, and is beneficial to prolong the service life of the battery.
  • doping elements are added to the active particles, and the doping elements can be, for example, one or more of Ti, V, Co, Ni, Cu, Zn, Mg, Al, Ca, Nb, Mo , Adding doping elements in active particles can further improve the conductivity and cycle performance of battery cathode materials.
  • the active particles have a higher compaction density than lithium manganese iron phosphate particles, for example, the compaction density of lithium cobaltate is 4g/cm 3 , and the compaction density of nickel-cobalt lithium manganate and nickel-cobalt lithium aluminate The density is 3.7-3.9g/cm 3 , and the compacted density of lithium manganate is 2.9-3.2g/cm 3 . Therefore, active particles can also increase the volumetric energy density of battery cathode materials.
  • the mass percentage of lithium manganese iron phosphate particles in the positive electrode material of the battery is 70% to 90%, and the mass percentage of lithium manganese iron phosphate particles in the positive electrode material of the battery is specifically but not limited to 70%, 70% %, 75%, 80%, 85% or 90%, a higher content of lithium manganese iron phosphate particles can ensure that the positive electrode material of the battery has good safety performance and cycle performance.
  • the active particles account for 10% to 30% of the mass percentage of the positive electrode material of the battery, and the active particles account for the mass percentage of the positive electrode material of the battery.
  • the content of active particles within the above range can fully fill the gap between lithium manganese iron phosphate, which can effectively improve the compaction density of battery positive electrode materials, and the content of active particles within the above range will increase The safety of the positive electrode material of the battery, and the number of active particles within the above range prevents the gaps between the lithium manganese iron phosphate particles from being further expanded, thereby reducing the compacted density.
  • the ratio of the median diameter of the lithium manganese iron phosphate particles to the active particles is 3-8.
  • the ratio of the median diameter of the lithium manganese iron phosphate particles to the active particles may be, but not limited to, 3, 4, 5, 6, 7 or 8. Controlling the ratio of the median particle size of lithium manganese iron phosphate particles to active particles can ensure that particles of different particle sizes can achieve good particle gradation, thereby effectively reducing the void ratio.
  • the ratio of the median diameter of the lithium manganese iron phosphate particles to the active particles within the above range can realize the effective matching of large particles and small particles, thereby reducing the gap between particles.
  • the median particle diameter D 50 of the lithium manganese iron phosphate particles is 2 ⁇ m-15 ⁇ m.
  • the median particle diameter D 50 of the lithium manganese iron phosphate particles may specifically be, but not limited to, 2 ⁇ m, 5 ⁇ m, 7 ⁇ m, 10 ⁇ m or 15 ⁇ m.
  • the median diameter of the lithium manganese iron phosphate particles is within the above range, the diffusion path of lithium ions can be prevented from becoming longer, thereby improving the rate performance of the battery.
  • the median particle diameter D 50 of the active particles is 0.5 ⁇ m-5 ⁇ m.
  • the median diameter D 50 of the active particles may specifically be, but not limited to, 0.5 ⁇ m, 1 ⁇ m, 3 ⁇ m or 5 ⁇ m.
  • the porosity can be effectively reduced; when the median particle size of the active particles is within the above range, a good filling effect can be achieved, thereby reducing the specific surface area of the positive electrode material and improving the Processing performance.
  • the mass ratio of lithium manganese iron phosphate particles to active particles is 1:(0.2-0.35).
  • the mass ratio of lithium manganese iron phosphate particles to active particles may be, but not limited to, 1:0.2, 1:0.25, 1:0.3 or 1:0.35.
  • Figure 2 is a schematic structural view of a positive electrode material provided by the present application, please refer to Figure 2, the particle size of the active particles in the positive electrode material is smaller than that of lithium manganese iron phosphate particles, and the number of active particles is more than that of lithium manganese iron phosphate the number of .
  • the positive electrode material in Figure 1 has a smaller particle size of the active particles, and the number of active particles is also kept within a reasonable range, so that the active particles will not accumulate and prevent the formation of gaps between the active particles. Porous, which can effectively improve the compaction density of the positive electrode material.
  • the number of lithium manganese iron phosphate particles in the positive electrode material of the battery per unit volume accounts for 25%-75%.
  • the percentage of the total particle number of the positive electrode material can improve the space utilization rate and increase the volumetric energy density of the positive electrode material of the battery.
  • the active particles include primary active particles and secondary active particles, that is, active particles of different particle sizes are used to fill the gaps between lithium manganese iron phosphate particles.
  • Figure 3 provides an example of an embodiment of the present application.
  • the schematic diagram of the structure of the positive electrode material of the battery please refer to Fig. 3, wherein, the active particles 12 are filled in the pores of lithium manganese iron phosphate particles 11, the active particles 12 include primary active particles 121 and secondary active particles 122, the secondary active particles 122 is filled between primary active particles 121 and lithium iron manganese phosphate particles 11 .
  • the median diameter of the primary active particles is 0.5 ⁇ m-5 ⁇ m, and the median diameter of the secondary active particles is 0.1 ⁇ m-2 ⁇ m. In some embodiments of the present application, the ratio of the median diameter of the primary active particles to the secondary active particles is 3-8. Controlling the ratio of the median particle size of the primary active particles to the secondary active particles can ensure that the secondary active particles can further fill the gap between the active particles and the lithium manganese iron phosphate particles, thereby fully increasing the compaction density of the positive electrode material of the battery.
  • the compacted density of the positive electrode material of the battery is 2.4g/cm 3 -3.2g/cm 3 .
  • the compacted density of the positive electrode material of the battery may be, but not limited to, 2.4 g/cm 3 , 2.6 g/cm 3 , 2.8 g/cm 3 , 3.0 g/cm 3 or 3.2 g/cm 3 .
  • the battery positive electrode material of the present application has a relatively high compaction density, and making it into a positive electrode sheet and applying it in a battery can not only improve the safety and low temperature performance of the battery, but also the battery can have a higher volumetric energy density and mass energy density .
  • the present application also provides a preparation method for the above-mentioned battery positive electrode material, including:
  • the lithium manganese iron phosphate particles and the active particles are mixed, and the mixing method may be one or more of ball milling, powder mixing or liquid phase mixing.
  • the present application also provides a positive electrode sheet, which includes a current collector and a positive electrode material layer disposed on the current collector, wherein the positive electrode material layer includes the battery positive electrode material of the present application.
  • the positive electrode material layer can be prepared by mixing the battery positive electrode material, conductive agent, binder and solvent to form a positive electrode slurry, and coating and drying the positive electrode slurry to obtain the positive electrode material layer.
  • the binder and the solvent can be mixed first, and then the conductive agent is added after being fully stirred, and then the positive electrode material of the battery is added after stirring, and the positive electrode slurry is obtained by sieving after stirring.
  • conductive agents, binders and solvents are conventional choices in the field of batteries.
  • the binder may be selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polyimide ( PI), polyacrylic acid (PAA), polyacrylate, polyolefin, sodium carboxymethylcellulose (CMC) and sodium alginate.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVA polyvinyl alcohol
  • SBR styrene-butadiene rubber
  • PAN polyacrylonitrile
  • PI polyimide
  • PAA polyacrylic acid
  • polyacrylate polyolefin
  • CMC sodium carboxymethylcellulose
  • Na alginate sodium alginate.
  • the conductive agent may be selected from one or more of carbon nanotubes, carbon black and graphene.
  • the present application also provides a secondary battery, which includes a positive electrode, a negative electrode, an electrolyte, and a separator between the positive electrode and the negative electrode, wherein the positive electrode includes the positive electrode sheet provided in the present application.
  • the negative electrode of the secondary battery may be any negative electrode known in the art.
  • the negative electrode may include one or more of carbon-based negative electrodes, silicon-based negative electrodes, tin-based negative electrodes, and lithium negative electrodes.
  • the carbon-based negative electrode can include graphite, hard carbon, soft carbon, graphene, etc.;
  • the tin-based negative electrode can include tin-containing materials such as tin, tin-carbon, tin-oxygen, and tin metal compounds, or the mixed material of the tin-containing material and non-tin-containing materials such as graphite;
  • the lithium negative electrode can include metal lithium or lithium alloy.
  • the lithium alloy may be at least one of lithium-silicon alloy, lithium-sodium alloy, lithium-potassium alloy, lithium-aluminum alloy, lithium-tin alloy and lithium-indium alloy.
  • the current collector of the negative electrode is copper foil
  • the negative electrode active material includes natural graphite, artificial graphite, hard carbon, soft carbon, lithium titanate, iron oxide, lithium titanium phosphate, titanium dioxide, silicon, silicon oxide, One or more of tin and its oxides and antimony and its oxides
  • binders include polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC) and styrene-butadiene latex ( One or more of SBR)
  • the conductive agent includes one or more of acetylene black, Ketjen black, Super-P, carbon nanotubes, carbon nanofibers, activated carbon and graphene.
  • the preparation method of the negative electrode can adopt any method known in the
  • the separator of the secondary battery can be any separator known to those skilled in the art, for example, the separator can be polyolefin microporous membrane, polyethylene terephthalate, polyethylene felt, glass fiber felt or ultrafine One or more of glass fiber paper.
  • the electrolyte solution of the secondary battery includes a solution formed of an electrolyte lithium salt in a non-aqueous solvent.
  • the electrolyte lithium salt includes lithium hexafluorophosphate (LiPF 6 ), lithium perchlorate (LiClO 4 ), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium hexafluorosilicate ( Li 2 SiF 6 ), lithium tetraphenylborate (LiB(C 6 H5) 4 ), lithium chloride (LiCl), lithium bromide (LiBr), lithium chloroaluminate (LiAlCl 4 ), lithium fluorocarbonate (LiC( One or more of SO 2 CF 3 ) 3 ), LiCH 3 SO 3 , LiN(SO 2 CF 3 ) 2 and LiN(SO 2 C 2 F 5 ) 2 .
  • the non-aqueous solvent includes one or more of chain acid esters and cyclic acid esters.
  • chain esters include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and dipropyl carbonate (DPC) ) in one or more.
  • the chain esters include chain organic esters containing fluorine, sulfur or unsaturated bonds.
  • the cyclic acid ester includes ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), ⁇ -butyrolactone ( ⁇ -BL) and sultone one or more.
  • the cyclic esters include cyclic organic esters containing fluorine, sulfur or unsaturated bonds.
  • the non-aqueous solvent includes one or more of chain ether and cyclic ether solutions.
  • the cyclic ethers include tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), 1,3-dioxolane (DOL) and 4-methyl-1,3-dioxo One or more of cyclopentane (4-MeDOL).
  • the cyclic ether includes cyclic organic ethers containing fluorine, sulfur or unsaturated bonds.
  • chain ethers include dimethoxymethane (DMM), 1,2-dimethoxyethane (DME), 1,2-dimethoxypropane (DMP) and diethylene glycol One or more of dimethyl ether (DG).
  • the chain ethers include chain organic ethers containing fluorine, sulfur or unsaturated bonds.
  • the concentration of the electrolyte lithium salt in the electrolyte solution is 0.1 mol/L-15 mol/L. In some embodiments of the present application, the concentration of the electrolyte lithium salt is 1 mol/L-10 mol/L.
  • any one of lamination process or winding process may be used for the preparation of the secondary battery.
  • a stacking process is used to prepare batteries.
  • a method for preparing a positive electrode material for a battery comprising:
  • the slurry was coated on the surface of the aluminum foil with an area density of 200g/m 2 . After drying, the pole pieces were cut into 15mm positive pole pieces, and assembled with separators and lithium sheets to form 2032 button half-cells.
  • a method for preparing a positive electrode material for a battery comprising:
  • a method for preparing a positive electrode material for a battery comprising:
  • lithium manganese iron phosphate 100g of lithium nickel cobalt manganate and 100g of lithium cobaltate (LiCoO 2 ) into the ball mill for mixing.
  • the chemical formula of lithium manganese iron phosphate is LiMn 0.6 Fe 0.4 PO 4 , and the carbon content of lithium manganese iron phosphate is The content is 1.5%, the median particle size D 50 of lithium manganese iron phosphate is 15 ⁇ m; the chemical formula of nickel cobalt lithium manganate is LiNi 0.8 Co 0.1 Mn 0.1 O 2 , the median particle size D 50 of nickel cobalt lithium manganate is 3.2 ⁇ m; the median particle size of lithium cobaltate is 3.2 ⁇ m, after adding zirconium balls and ball milling for 5 hours, the positive electrode material of the battery is obtained.
  • the battery was prepared by the same method as in Example 1.
  • a method for preparing a positive electrode material for a battery comprising:
  • lithium manganese iron phosphate 100g of lithium nickel cobalt manganese oxide and 100g of lithium-rich manganese-based materials into the ball mill for mixing.
  • the chemical formula of lithium manganese iron phosphate is LiMn 0.6 Fe 0.4 PO 4 , and the carbon content of lithium manganese iron phosphate is 1.5%, the median particle size D 50 of lithium manganese iron phosphate is 15 ⁇ m;
  • the chemical formula of nickel cobalt lithium manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O 2 , the median particle size D 50 of nickel cobalt lithium manganese oxide is 3.2 ⁇ m;
  • the chemical formula of the lithium-rich manganese-based material is 0.5Li 2 MnO 3 ⁇ 0.5LiMnO 2 , and the median particle size of the lithium-rich manganese-based material is 3.2 ⁇ m.
  • a method for preparing a positive electrode material for a battery comprising:
  • a method for preparing a positive electrode material for a battery comprising:
  • a method for preparing a positive electrode material for a battery comprising:
  • a method for preparing a positive electrode material for a battery comprising:
  • a method for preparing a positive electrode material for a battery comprising:
  • a method for preparing a positive electrode material for a battery comprising:
  • a method for preparing a positive electrode material for a battery comprising:
  • lithium manganese iron phosphate 180g first grade nickel cobalt lithium manganese oxide, 20g second grade nickel cobalt lithium manganese oxide into the ball mill tank for mixing, wherein the chemical formula of lithium manganese iron phosphate is LiMn 0.6 Fe 0.4 PO 4
  • the carbon content is 1.5%
  • the median particle size D 50 of lithium manganese iron phosphate is 15 ⁇ m
  • the chemical formula of first-class nickel-cobalt lithium manganate is LiNi 0.8 Co 0.1 Mn 0.1 O 2
  • the median particle size of nickel-cobalt lithium manganate is The D 50 is 3.2 ⁇ m
  • the chemical formula of the secondary nickel cobalt lithium manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O 2
  • the median particle size D 50 of the nickel cobalt lithium manganese oxide is 1.0 ⁇ m
  • after adding zirconium balls and ball milling for 5 hours the battery is obtained Cathode material.
  • the battery was prepared by the same method as in Example 1.
  • the positive electrode material, conductive agent, and binder are dispersed in N-methylpyrrolidone at a mass ratio of 90:5:5
  • the conductive agent is carbon nanotubes
  • the binder is PVDF5130
  • the solid content of the slurry is 50%.
  • the slurry was coated on the surface of the aluminum foil with an area density of 200g/m 2 . After drying, the pole pieces were cut into 15mm pole pieces, and assembled with separators and lithium sheets to form 2032 button half cells.
  • lithium manganese iron phosphate Add 950g of lithium manganese iron phosphate and 50g of nickel-cobalt lithium manganese oxide into a ball mill for mixing.
  • the chemical formula of lithium manganese iron phosphate is LiMn 0.6 Fe 0.4 PO 4 , and the median particle size D 50 of lithium manganese iron phosphate is 15 ⁇ m;
  • the chemical formula of lithium manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O 2 , and the median particle size D 50 of nickel cobalt lithium manganese oxide is 3.5 ⁇ m.
  • the battery cathode material After adding zirconium balls and ball milling for 5 hours, the battery cathode material is obtained.
  • a battery was prepared using the same method as in Comparative Example 1.
  • lithium manganese iron phosphate Add 600g of lithium manganese iron phosphate and 400g of nickel-cobalt lithium manganese oxide into a ball mill for mixing.
  • the chemical formula of lithium manganese iron phosphate is LiMn 0.6 Fe 0.4 PO 4 , and the median particle size D 50 of lithium manganese iron phosphate is 15 ⁇ m;
  • the chemical formula of lithium manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O 2 , and the median particle size D 50 of nickel cobalt lithium manganese oxide is 3.5 ⁇ m.
  • the battery cathode material After adding zirconium balls and ball milling for 5 hours, the battery cathode material is obtained.
  • a battery was prepared using the same method as in Comparative Example 1.
  • lithium manganese iron phosphate Add 800g of lithium manganese iron phosphate and 200g of nickel-cobalt lithium manganese oxide into a ball mill for mixing.
  • the chemical formula of lithium manganese iron phosphate is LiMn 0.6 Fe 0.4 PO 4 , and the median particle size D 50 of lithium manganese iron phosphate is 12 ⁇ m;
  • the chemical formula of lithium manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O 2 , and the median particle size D 50 of nickel cobalt lithium manganate is 1 ⁇ m.
  • zirconium balls After adding zirconium balls, it is ball milled for 5 hours to obtain the positive electrode material of the battery.
  • a battery was prepared using the same method as in Comparative Example 1.
  • lithium manganese iron phosphate Add 800g of lithium manganese iron phosphate and 200g of nickel-cobalt lithium manganese oxide into a ball mill for mixing.
  • the chemical formula of lithium manganese iron phosphate is LiMn 0.6 Fe 0.4 PO 4 , and the median particle size D 50 of lithium manganese iron phosphate is 12 ⁇ m;
  • the chemical formula of lithium manganese oxide is LiNi 0.8 Co 0.1 Mn 0.1 O 2 , and the median particle size D 50 of nickel cobalt lithium manganese oxide is 5 ⁇ m.
  • the battery cathode material After adding zirconium balls and ball milling for 5 hours, the battery cathode material is obtained.
  • a battery was prepared using the same method as in Comparative Example 1.
  • the present application also provides effect examples.
  • Figure 4 is a scanning electron microscope image of the battery cathode material provided in Example 1 of the present application, please refer to Figure 4, in Figure 4, the particles with higher brightness are lithium nickel cobalt manganese oxide, and the particles with lower brightness are manganese phosphate Lithium particles. It can be seen from FIG. 4 that in the positive electrode material of the battery in Example 1, the small particles of nickel-cobalt lithium manganese oxide are tightly filled in the gaps between the lithium manganese iron phosphate particles. Obtain the particle size distribution of the battery positive electrode material of embodiment 1-11 and comparative example 1-6 by laser particle size analyzer, obtain the median particle size of the battery positive electrode material of embodiment 1-11 and comparative example 1-6 according to particle size distribution diameter D 50 , please refer to Table 1 for test results.
  • the measurement method includes: compacting the positive pole pieces of Examples 1-11 and Comparative Examples 1-6, from the positive pole Cut a disc with a fixed radius R on the surface of the disc, measure its mass M1 and thickness H1, intercept an aluminum foil disc with the same radius, measure its mass M2 and thickness H2, divide the mass difference by the volume of the positive electrode dressing and obtain the compacted density,
  • the formula for calculating the compacted density is as follows:
  • the battery anode materials of Examples 1-4 contain active particles with smaller particle diameters, so that the prepared battery has a higher mass energy density, and the implementation Compared with the battery of Comparative Example 1, the volumetric energy density of the battery of Examples 1-4 is 20% higher, which is due to the higher energy density of the active particles, and after optimization of particle packing, the compacted density of the positive electrode material of the battery is further improved. increase, thereby increasing the volumetric energy density.
  • the battery positive electrode material of embodiment 5-7 has higher compaction density, and this is because the quality of the battery positive electrode material lithium manganese iron phosphate of embodiment 5-7 is more appropriate than that of active particles.
  • active particles with a smaller particle size can effectively fill the gaps between lithium manganese iron phosphate, and the compacted density of the product is significantly improved compared with Comparative Example 2; but due to the limited size of the gaps between lithium manganese iron phosphate, Therefore, there is a certain limit to the amount of particles that can be filled in the gaps. After the amount of active particles reaches a certain value, the compacted density will be reduced instead. Therefore, the compacted density of the positive electrode material of the battery in Example 7 is lower than that in Example 5.
  • the positive electrode material of the battery can have a higher compaction density.
  • the mass energy density of the battery in Example 5-7 is also improved.
  • the particle size ratio of the lithium iron phosphate and the active particles in the positive electrode materials of the batteries in Examples 8-10 is 3-8, and the particles can be tightly packed.
  • the particle size difference between lithium manganese iron phosphate and active particles is relatively large, and there are still many gaps in the large particle size lithium manganese iron phosphate, that is, the gaps of large particles need to be filled with more small particles to achieve Tightly packed;
  • the particle size difference between lithium manganese iron phosphate and active particles in comparative example 5 is small, and the active particles cannot be filled into the gaps of lithium manganese iron phosphate, resulting in a decrease in the compacted density of the material;
  • lithium manganese iron phosphate The particle size of lithium manganese iron phosphate is much smaller than that of active particles, and the mass of lithium iron manganese phosphate is much larger than that of active particles, resulting in the number of particles of lithium manganese iron phosphate being far more than the number of active
  • Example 11 secondary filling is performed on the basis of primary filling, and secondary nickel-cobalt manganese oxide can be further filled in the remaining gaps after primary filling. It can be seen from the experimental results that Example 11 and Example 1 The positive electrode sheet has a higher compaction density, which shows that secondary filling can effectively increase the compaction density of the positive electrode sheet, thereby increasing the mass energy density and volumetric energy density of the battery.
  • the positive electrode material of the battery is prepared as a positive electrode sheet and applied in the battery so that the battery has a higher mass energy density and volume energy density.

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Abstract

一种电池正极材料，该电池正极材料包括磷酸锰铁锂颗粒和分散在磷酸锰铁锂颗粒间隙中的活性颗粒；活性颗粒包括镍钴锰酸锂颗粒、镍钴铝酸锂颗粒、富锂锰基材料颗粒、钴酸锂颗粒、尖晶石锰酸锂LiMn2O4颗粒和层状锰酸锂LiMnO2颗粒中的一种或多种；磷酸锰铁锂与活性颗粒的中位粒径之比为3～8；电池正极材料中，磷酸锰铁锂的质量百分含量为70％～90％，活性颗粒的质量百分含量为10％～30％。还提供了上述电池正极材料的应用。

Description

电池正极材料及其应用
本申请要求于2021年9月24日提交中国专利局、申请号为202111126603.2、发明名称为“一种电池正极材料及其应用”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及二次电池领域，具体涉及一种电池正极材料及其应用。
背景技术
磷酸盐类材料LiMPO 4(M＝Fe、Mn、Ni、Co)用作二次电池正极材料时具有结构稳定、与电解液反应活性小、安全性高、电池循环性好等诸多优点，然而现有的磷酸盐体系的电池压实密度和能量密度较低，不利于电池的应用。因此，有必要提供一种电池正极材料，以使极片具有较高压实密度，使电池可以兼顾高能量密度、高循环稳定性和安全性。
发明内容
本申请第一方面提供了一种电池正极材料，所述电池正极材料包括磷酸锰铁锂颗粒和填充在所述磷酸锰铁锂颗粒间隙中的活性颗粒；所述活性颗粒包括镍钴锰酸锂颗粒、镍钴铝酸锂颗粒、富锂锰基材料颗粒、钴酸锂颗粒、尖晶石锰酸锂LiMn 2O 4颗粒和层状锰酸锂LiMnO 2颗粒中的一种或多种；所述磷酸锰铁锂与所述活性颗粒的中位粒径之比为3～8；所述电池正极材料中，所述磷酸锰铁锂的质量百分含量为70％～90％，所述活性颗粒的质量百分含量为10％～30％。
在本申请一实施例中，所述磷酸锰铁锂颗粒的中位粒径为2μm-15μm。
在本申请一实施例中，所述活性颗粒的中位粒径为0.5μm-5μm。
在本申请一实施例中，所述活性颗粒包括一级活性颗粒和二级活性颗粒，所述一级活性颗粒的中位粒径为0.5μm-5μm，所述二级活性颗粒的中位粒径为0.1μm-2μm。
在本申请一实施例中，所述磷酸锰铁锂颗粒与所述活性颗粒的质量比为1:(0.2～0.35)。
在本申请一实施例中，所述磷酸锰铁锂颗粒包括LiMn xFe 1-xPO 4，其中，0.5≤x≤0.9。
在本申请一实施例中，所述磷酸锰铁锂颗粒包括碳，所述碳占所述磷酸锰铁锂颗粒的质量百分含量为1％～3％。
在本申请一实施例中，所述磷酸锰铁锂颗粒还包括掺杂元素，所述掺杂元素包括Ti、V、Co、Ni、Cu、Zn、Mg、Ca、Al、Nb、Mo中的一种或多种。
在本申请一实施例中，所述镍钴锰酸锂颗粒包括LiNi aCo bMn 1-a-bO 2，其中，0＜a＜1，0 ＜b＜1，0＜1-a-b＜1。
在本申请一实施例中，所述镍钴锰酸锂颗粒还包括掺杂元素，所述掺杂元素包括Ti、V、Fe、Cu、Zn、Mg、Ca、Al、Nb、Mo中的一种或多种。
在本申请一实施例中，所述镍钴铝酸锂颗粒包括LiNi mCo nAl 1-m-nO 2，其中，0＜m＜1，0＜n＜1，0＜1-m-n＜1。
在本申请一实施例中，所述镍钴铝酸锂颗粒还包括掺杂元素，所述掺杂元素包括Ti、V、Mn、Fe、Cu、Zn、Mg、Ca、Nb、Mo中的一种或多种。
在本申请一实施例中，所述富锂锰基材料颗粒包括yLi 2MnO 3·(1-y)LiMO 2，其中，0＜y＜1，所述M包括Mn、Ni或Co中至少一种。
在本申请一实施例中，所述富锂锰基材料颗粒还包括掺杂元素，所述掺杂元素包括Ti、V、Fe、Co、Cu、Zn、Mg、Ca、Nb、Mo中的一种或多种。
在本申请一实施例中，所述电池正极材料的压实密度为2.4g/cm 3～3.2g/cm 3。
在本申请一实施例中，所述磷酸锰铁锂颗粒和所述活性颗粒之间无团聚的作用，所述活性颗粒不以包覆形式附着在所述磷酸锰铁锂颗粒的颗粒表面。
在本申请一实施例中，所述活性颗粒相比于所述磷酸锰铁锂颗粒具有更高的压实密度。
本申请第二方面提供了一种正极极片，包括集流体和设置在所述集流体上的正极材料层，所述正极材料层包括如第一方面所述的电池正极材料。
本申请第三方面提供了一种二次电池，包括正极、负极、隔膜和电解液，所述正极包括如第二方面所述的正极极片。
附图说明
图1为本申请一实施例提供的电池正极材料结构示意图；
图2为本申请提供的一种正极材料的结构示意图；
图3为本申请一实施例提供的电池正极材料的结构示意图；
图4为本申请实施例1提供的电池正极材料的扫描电镜图。
需指出的是，电池正极材料结构示意图展示的是二维方向上的颗粒分布，而实际上应是三维上的立体图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
以磷酸铁锂为代表的磷酸盐正极材料具有循环寿命长，安全性高，环境友好，成本低等优点，在锂离子电池正极材料体系中占有重要地位。相较于磷酸铁锂，磷酸锰铁锂具有更高的理论能量密度，然而磷酸锰铁锂的电子和离子传输速率较低，限制其容量的发挥，为提高磷酸锰铁锂正极材料的电导率需要对磷酸锰铁锂进行碳包覆，然而碳的引入会降低材料的压实密度。为提高正极材料的压实密度，本申请提供了一种电池正极材料，该电池正极材料通过对不同组分进行颗粒级搭配使材料具有较高的质量能量密度和体积能量密度，采用该电池正极材料的电池能够具有较高能量密度和安全性能并且还具有良好的低温性能。图1为本申请一实施例提供的电池正极材料结构示意图，请参阅图1，本申请的电池正极材料10包括磷酸锰铁锂颗粒11和分散在磷酸锰铁锂颗粒间隙中的活性颗粒12。本申请中，活性颗粒与磷酸锰铁锂颗粒为物理共混的体系，较小粒径的活性颗粒填充在磷酸锰铁锂颗粒的间隙中，需要注意的是，本申请的电池正极材料中，颗粒之间无团聚的作用，小粒径的颗粒并不以包覆形式附着在大粒径的颗粒表面，而是以单一的分散态与大颗粒进行堆积形成物理共混的体系。
本申请的电池正极材料中，磷酸锰铁锂颗粒具有较大的粒径，较小粒径的活性颗粒可填充在磷酸锰铁锂颗粒的间隙中，活性颗粒相比于磷酸锰铁锂颗粒具有更高的压实密度，从而在不改变材料整体体积的前提下显著地提高材料整体的压实密度，使电池正极材料具有较高的体积能量密度；并且活性颗粒的质量比容量和电压也高于磷酸锰铁锂颗粒，从而使电池正极材料也具有较高的质量能量密度，除此之外，活性颗粒具有良好的低温性能，有利于提高电池正极材料的低温性能。
本申请中，磷酸锰铁锂包括LiMn xFe 1-xPO 4，其中，0.5≤x≤0.9，本申请一些实施方式中，可对磷酸锰铁锂进行元素掺杂以提高磷酸锰铁锂的导电性，掺杂元素例如可以是Ti、V、Co、Ni、Cu、Zn、Mg、Ca、Al、Nb、Mo中的一种或多种。掺杂元素占磷酸锰铁锂中全部过渡金属元素的质量百分含量为0.2％-2％。本申请一些实施方式中，磷酸锰铁锂还包括质量百分含量为1％～3％的碳，一定含量的碳有利于提高电池正极材料的导电性。
本申请中，活性颗粒包括镍钴锰酸锂颗粒、镍钴铝酸锂颗粒、富锂锰基材料颗粒、钴酸锂颗粒和锰酸锂颗粒中的一种或多种。本申请实施方式中，镍钴锰酸锂颗粒包括LiNi aCo bMn 1-a-bO 2，其中，0＜a＜1，0＜b＜1，0＜1-a-b＜1；镍钴铝酸锂颗粒包括LiNi mCo nAl 1-m-nO 2，其中，0＜m＜1，0＜n＜1，0＜1-m-n＜1；富锂锰基材料颗粒包括yLi 2MnO 3·(1-y)LiMO 2，其中，0＜y＜1，M包括Mn、Ni或Co中至少一种；钴酸锂颗粒的化学式为LiCoO 2；锰酸锂颗粒包括尖晶石锰酸锂LiMn 2O 4或层状锰酸锂LiMnO 2中的一种或多种。采用上述活性颗粒不仅能够提高电池正极材料的能量密度，并且可以有效地改善电池的低温性能，有利于延长电池的使用寿命。本申请一些实施方式中，活性颗粒中添加有掺杂元素，掺杂元素例如可以是Ti、V、Co、Ni、Cu、Zn、Mg、Al、Ca、Nb、Mo中的一种或多种， 在活性颗粒中添加掺杂元素可以进一步改善电池正极材料的导电性和循环性能。
本申请中，活性颗粒相比于磷酸锰铁锂颗粒具有更高的压实密度，例如钴酸锂的压实密度为4g/cm 3，镍钴锰酸锂和镍钴铝酸锂的压实密度为3.7～3.9g/cm 3，锰酸锂的压实密度为2.9～3.2g/cm 3。因此，活性颗粒也能够提高电池正极材料的体积能量密度。
本申请实施方式中，磷酸锰铁锂颗粒占电池正极材料的质量百分含量为70％～90％，磷酸锰铁锂颗粒占电池正极材料的质量百分含量具体但不限于为70％、70％、75％、80％、85％或90％，较高含量的磷酸锰铁锂颗粒可保证电池正极材料具有良好的安全性能和循环性能。本申请实施方式中，活性颗粒占电池正极材料的质量百分含量为10％～30％，活性颗粒占电池正极材料的质量百分含量具体可以但不限于为10％、15％、20％、25％或30％，活性颗粒的含量在上述范围内则可以充分填充磷酸锰铁锂之间的空隙，能够有效地提高电池正极材料的压实密度，活性颗粒的含量在上述范围内则会提高电池正极材料的安全性，并且活性颗粒的数量在上述范围内使得磷酸锰铁锂颗粒之间的空隙不会被进一步扩大，从而不会使压实密度降低。
本申请实施方式中，磷酸锰铁锂颗粒与活性颗粒的中位粒径之比为3～8。磷酸锰铁锂颗粒与活性颗粒的中位粒径之比具体可以但不限于为3、4、5、6、7或8。控制磷酸锰铁锂颗粒与活性颗粒的中位粒径之比可以保证不同粒径的颗粒能够实现良好的颗粒级配，从而有效地降低空隙率。磷酸锰铁锂颗粒与活性颗粒的中位粒径之比在上述范围内能够实现大颗粒与小颗粒的有效匹配，进而降低颗粒间的空隙。
本申请实施方式中，磷酸锰铁锂颗粒的中位粒径D 50为2μm-15μm。磷酸锰铁锂颗粒的中位粒径D 50具体可以但不限于为2μm、5μm、7μm、10μm或15μm。当磷酸锰铁锂颗粒的中位粒径在上述范围内时，能够防止锂离子的扩散路径变长，从而提高电池的倍率性能。本申请实施方式中，活性颗粒的中位粒径D 50为0.5μm-5μm。活性颗粒的中位粒径D 50具体可以但不限于为0.5μm、1μm、3μm或5μm。活性颗粒的中位粒径在上述范围内时，能够有效地降低空隙率；活性颗粒中位粒径在上述范围内时，能够实现良好的填充效果，从而减小了正极材料比表面积，提高了加工性能。
本申请一些实施方式中，磷酸锰铁锂颗粒与活性颗粒的质量比为1:(0.2～0.35)。磷酸锰铁锂颗粒与活性颗粒的质量比具体可以但不限于为1:0.2、1:0.25、1:0.3或1:0.35。在大颗粒与小颗粒粒径匹配的前提下，进一步控制磷酸锰铁锂颗粒与活性颗粒的质量比可以优化颗粒分布，使小粒径的活性颗粒填充在大粒径的磷酸锰铁锂间隙，即活性颗粒能够直接填充在磷酸锰铁锂颗粒间隙，而不破坏原本磷酸锰铁锂颗粒间隙的排布，同时活性颗粒的个数可以保持在合理范围，因此能够防止活性颗粒之间发生堆积，进而缩小电池正极材料的间隙。图2为本申请提供的一种正极材料的结构示意图，请参阅图2，该正极材料中活性颗粒的粒径小于 磷酸锰铁锂颗粒的粒径，活性颗粒的个数多于磷酸锰铁锂的个数。图1的正极材料与图2的正极材料相比，活性颗粒的粒径较小，同时活性颗粒的个数也保持在合理范围内，使得活性颗粒不会发生堆积，防止活性颗粒之间形成较多孔隙，从而能够有效地提高正极材料的压实密度。本申请一些实施方式中，单位体积的电池正极材料中磷酸锰铁锂颗粒的个数占比为25％-75％，其中，个数占比指的是磷酸锰铁锂颗粒的颗粒数目占电池正极材料总颗粒数目的百分比。控制磷酸锰铁锂颗粒的个数占比可以提高空间利用率，提高电池正极材料的体积能量密度。
本申请一些实施方式中，活性颗粒包括一级活性颗粒和二级活性颗粒，即采用不同粒径的活性颗粒对磷酸锰铁锂颗粒之间的空隙进行填充，图3为本申请一实施例提供的电池正极材料的结构示意图，请参阅图3，其中，活性颗粒12填充在磷酸锰铁锂颗粒11的孔隙中，活性颗粒12包括一级活性颗粒121和二级活性颗粒122，二级活性颗粒122填充在一级活性颗粒121和磷酸锰铁锂颗粒11之间。本申请一些实施方式中，一级活性颗粒的中位粒径为0.5μm-5μm，二级活性颗粒的中位粒径为0.1μm-2μm。本申请一些实施方式中，一级活性颗粒与二级活性颗粒的中位粒径之比为3～8。控制一级活性颗粒与二级活性颗粒的中位粒径之比可保证二级活性颗粒能够进一步填充以及活性颗粒与磷酸锰铁锂颗粒的空隙，从而充分地提高电池正极材料的压实密度。
本申请实施方式中，电池正极材料的压实密度为2.4g/cm 3～3.2g/cm 3。电池正极材料的压实密度具体可以但不限于为2.4g/cm 3、2.6g/cm 3、2.8g/cm 3、3.0g/cm 3或3.2g/cm 3。本申请的电池正极材料具有较高的压实密度，将其制成正极极片并应用在电池中不仅可以提高电池的安全性和低温性能，并且电池能够具有较高体积能量密度和质量能量密度。
本申请还提供了上述电池正极材料的制备方法，包括：
将磷酸锰铁锂颗粒和活性颗粒混合，混合的方式可以是球磨混合、粉体混合或液相混合中的一种或多种。
本申请还提供了一种正极极片，该正极极片包括集流体和设置在集流体上的正极材料层，其中，正极材料层包括本申请的电池正极材料。本申请中，正极材料层的制备可以是将电池正极材料、导电剂、粘结剂和溶剂混合形成正极浆料，将正极浆料经涂覆、干燥后得到正极材料层。在配制正极浆料时，可以先将粘结剂与溶剂混合，充分搅拌后，再加入导电剂，经搅拌后再加入电池正极材料，搅拌后过筛得到正极浆料。其中，导电剂、粘结剂和溶剂为电池领域的常规选择。例如，粘结剂可以选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇(PVA)、丁苯橡胶(SBR)、聚丙烯腈(PAN)、聚酰亚胺(PI)、聚丙烯酸(PAA)、聚丙烯酸酯、聚烯烃、羧甲基纤维素钠(CMC)和海藻酸钠中的一种或多种。导电剂可以选自碳纳米管、炭黑以及石墨烯中的一种或多种。
本申请还提供了一种二次电池，该二次电池包括正极、负极、电解液以及位于正极与负极之间的隔膜，其中，正极包括本申请提供的正极极片。
本申请中，二次电池的负极可以是本领域公知的任意负极。本申请实施方式中，负极可包括碳基负极、硅基负极、锡基负极和锂负极中的一种或多种。其中碳基负极可包括石墨、硬碳、软碳、石墨烯等；硅基负极可包括硅、硅碳、硅氧、硅金属化合物等含硅材料或者此含硅材料与非含硅材料如石墨的混合材料；锡基负极可包括锡、锡碳、锡氧、锡金属化合物等含锡材料或者此含锡材料与非含锡材料如石墨的混合材料；锂负极可包括金属锂或锂合金。锂合金具体可以是锂硅合金、锂钠合金、锂钾合金、锂铝合金、锂锡合金和锂铟合金中的至少一种。本申请一些实施例中，负极的集流体为铜箔，负极活性材料包括天然石墨、人造石墨、硬碳、软碳、钛酸锂、氧化铁、磷酸钛锂、二氧化钛、硅、氧化亚硅、锡及其氧化物和锑及其氧化物中的一种或多种；粘结剂包含聚丙烯酸(PAA)、聚偏氟乙烯(PVDF)、羧甲基纤维素(CMC)和丁苯乳胶(SBR)中的一种或多种；导电剂包括乙炔黑、科琴碳黑、Super-P、碳纳米管、碳纳米纤维、活性炭和石墨烯中的一种或多种。本申请中，负极的制备方法可以采用本领域公知的任意方法。
本申请中，二次电池的隔膜可以是本领域技术人员公知的任意隔膜，例如隔膜可以是聚烯烃微多孔膜、聚对苯二甲酸乙二醇酯、聚乙烯毡、玻璃纤维毡或超细玻璃纤维纸中的一种或多种。
本申请中，二次电池的电解液包括电解质锂盐在非水溶剂中形成的溶液。本申请实施方式中，电解质锂盐包括六氟磷酸锂(LiPF 6)、高氯酸锂(LiClO 4)、四氟硼酸锂(LiBF 4)、六氟砷酸锂(LiAsF 6)、六氟硅酸锂(Li 2SiF 6)、四苯基硼酸锂(LiB(C 6H5) 4)、氯化锂(LiCl)、溴化锂(LiBr)、氯铝酸锂(LiAlCl 4)、氟烃基磺酸锂(LiC(SO 2CF 3) 3)、LiCH 3SO 3、LiN(SO 2CF 3) 2和LiN(SO 2C 2F 5) 2中的一种或多种。本申请一些实施方式中，非水溶剂包括链状酸酯和环状酸酯中的一种或多种。本申请一些实施方式中，链状酸酯包括碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸甲丙酯(MPC)和碳酸二丙酯(DPC)中的一种或多种。本申请一些实施方式中，链状酸酯包括含氟、含硫或含不饱和键的链状有机酯类。本申请一些实施方式中，环状酸酯包括碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸亚乙烯酯(VC)、γ-丁内酯(γ-BL)和磺内酯中的一种或多种。本申请一些实施方式中，环状酸酯包括含氟、含硫或含不饱和键的环状有机酯。本申请一些实施方式中，非水溶剂包括链状醚和环状醚溶液中的一种或多种。本申请一些实施方式中，环状醚包括四氢呋喃(THF)、2-甲基四氢呋喃(2-MeTHF)、1,3-二氧戊烷(DOL)和4-甲基-1,3-二氧环戊烷(4-MeDOL)中的一种或多种。本申请一些实施方式中，环状醚包括含氟、含硫或含不饱和键的环状有机醚。本申请一些实施方式中，链状醚包括二甲氧基甲烷(DMM)、1,2-二甲氧基乙烷(DME)、1,2-二甲氧基丙 烷(DMP)和二甘醇二甲醚(DG)中的一种或多种。本申请一些实施方式中，链状醚包括含氟、含硫或含不饱和键的链状有机醚。本申请实施方式中，电解液中电解质锂盐的浓度为0.1mol/L-15mol/L。本申请一些实施方式中，电解质锂盐的浓度为1mol/L-10mol/L。
本申请实施方式中，二次电池的制备可以采用叠片工艺或卷绕工艺中的任意一种。本申请一些实施例中，采用叠片工艺制备电池。
下面分多个实施例对本申请技术方案进行进一步的说明。
实施例1
一种电池正极材料的制备方法，包括：
将800g磷酸锰铁锂和200g镍钴锰酸锂加入混料机进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为15μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为3.2μm，以30rpm的速度机械混合5h，得到电池正极材料。
将制备得到的电池正极材料与导电剂、粘结剂按照90：5：5的质量比分散于N-甲基吡咯烷酮中，其中，导电剂为碳纳米管，粘结剂为PVDF5130，浆料的固含量为50％。将浆料涂覆在铝箔表面，涂覆的面密度为200g/m 2，烘干后将极片裁成15毫米的正极极片，并与隔膜、锂片组装成2032扣式半电池。
实施例2
一种电池正极材料的制备方法，包括：
将800g磷酸锰铁锂和200g镍钴铝酸锂加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为15μm；镍钴铝酸锂的化学式为LiNi 0.8Co 0.15Al 0.05O 2，镍钴铝酸锂的中位粒径D 50为3.2μm，加入锆球后球磨5h，得到电池正极材料。采用与实施例1相同的方法制备得到电池。
实施例3
一种电池正极材料的制备方法，包括：
将800g磷酸锰铁锂、100g镍钴锰酸锂和100g钴酸锂(LiCoO 2)加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为15μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为3.2μm；钴酸锂的中位粒径为3.2μm，加入锆球后球磨5h，得到电池正极材料。采用与实施例1相同的方法制备得到电池。
实施例4
一种电池正极材料的制备方法，包括：
将800g磷酸锰铁锂、100g镍钴锰酸锂和100g富锂锰基材料加入球磨罐进行混合，其中 磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为15μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为3.2μm；富锂锰基材料的化学式为0.5Li 2MnO 3·0.5LiMnO 2，富锂锰基材料的中位粒径为3.2μm，加入锆球后球磨5h，得到电池正极材料。采用与实施例1相同的方法制备得到电池。
实施例5
一种电池正极材料的制备方法，包括：
将800g磷酸锰铁锂、200g镍钴锰酸锂加入混料机进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为15μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为3.5μm，以30rpm的速度机械混合5h，得到电池正极材料。采用与实施例1相同的方法制备得到电池。
实施例6
一种电池正极材料的制备方法，包括：
将900g磷酸锰铁锂和100g镍钴铝酸锂加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为15μm；镍钴铝酸锂的化学式为LiNi 0.8Co 0.15Al 0.05O 2，镍钴铝酸锂的中位粒径D 50为3.5μm，加入锆球后球磨5h，得到电池正极材料。采用与实施例1相同的方法制备得到电池。
实施例7
一种电池正极材料的制备方法，包括：
将700g磷酸锰铁锂、300g镍钴锰酸锂加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为15μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为3.5μm；加入锆球后球磨5h，得到电池正极材料。采用与实施例1相同的方法制备得到电池。
实施例8
一种电池正极材料的制备方法，包括：
将800g磷酸锰铁锂和200g镍钴锰酸锂加入混料机进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为12μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为4μm，以30rpm的速度机械混合5h，得到电池正极材料。采用与实施例1相同的方法制备得到电池。
实施例9
一种电池正极材料的制备方法，包括：
将800g磷酸锰铁锂和200g镍钴铝酸锂加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为12μm；镍钴 铝酸锂的化学式为LiNi 0.8Co 0.15Al 0.05O 2，镍钴铝酸锂的中位粒径D 50为2.4μm，加入锆球后球磨5h，得到电池正极材料。采用与实施例1相同的方法制备得到电池。
实施例10
一种电池正极材料的制备方法，包括：
将800g磷酸锰铁锂、200g镍钴锰酸锂加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为12μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为1.5μm，加入锆球后球磨5h，得到电池正极材料。采用与实施例1相同的方法制备得到电池。
实施例11
一种电池正极材料的制备方法，包括：
将800g磷酸锰铁锂、180g一级镍钴锰酸锂、20g二级镍钴锰酸锂加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的含碳量为1.5％，磷酸锰铁锂的中位粒径D 50为15μm；一级镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为3.2μm，二级镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为1.0μm，加入锆球后球磨5h，得到电池正极材料。采用与实施例1相同的方法制备得到电池。
对比例1
以中位粒径D 50为15μm的磷酸锰铁锂LiMn 0.6Fe 0.4PO 4作为正极材料，将正极材料与导电剂、粘结剂按照90：5：5的质量比分散于N-甲基吡咯烷酮中，其中，导电剂为碳纳米管，粘结剂为PVDF5130，浆料的固含量为50％。将浆料涂覆在铝箔表面，涂覆的面密度为200g/m 2，烘干后将极片裁成15毫米的极片，并与隔膜、锂片组装成2032扣式半电池。
对比例2
将950g磷酸锰铁锂、50g镍钴锰酸锂加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的中位粒径D 50为15μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为3.5μm，加入锆球后球磨5h，得到电池正极材料。采用与对比例1相同的方法制备得到电池。
对比例3
将600g磷酸锰铁锂、400g镍钴锰酸锂加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的中位粒径D 50为15μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为3.5μm，加入锆球后球磨5h，得到电池正极材料。采用与对比例1相同的方法制备得到电池。
对比例4
将800g磷酸锰铁锂、200g镍钴锰酸锂加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的中位粒径D 50为12μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为1μm，加入锆球后球磨5h，得到电池正极材料。采用与对比例1相同的方法制备得到电池。
对比例5
将800g磷酸锰铁锂、200g镍钴锰酸锂加入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的中位粒径D 50为12μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为5μm，加入锆球后球磨5h，得到电池正极材料。采用与对比例1相同的方法制备得到电池。
对比例6
将800g磷酸锰铁锂、100g镍钴锰酸锂、100g锰酸锂入球磨罐进行混合，其中磷酸锰铁锂的化学式为LiMn 0.6Fe 0.4PO 4，磷酸锰铁锂的中位粒径D 50为1.5μm；镍钴锰酸锂的化学式为LiNi 0.8Co 0.1Mn 0.1O 2，镍钴锰酸锂的中位粒径D 50为15μm，锰酸锂的化学式为LiMn 2O 4，锰酸锂的中位粒径D 50为15μm，加入锆球后球磨5h，得到电池正极材料。采用与对比例1相同的方法制备得到电池。
效果实施例
为验证本申请制得的电池性能，本申请还提供了效果实施例。
1)图4为本申请实施例1提供的电池正极材料的扫描电镜图，请参阅图4，在图4中，较高亮度的颗粒为镍钴锰酸锂，亮度较低的颗粒为磷酸锰铁锂颗粒。由图4可以看出，实施例1的电池正极材料中，小颗粒的镍钴锰酸锂紧密地填充在磷酸锰铁锂颗粒的间隙。通过激光粒度仪得到实施例1-11和对比例1-6的电池正极材料的粒径分布，根据粒径分布得出实施例1-11和对比例1-6的电池正极材料的中位粒径D 50，测试结果请参阅表1。
2)对实施例1-11和对比例1-6的正极极片进行压实密度测量，测量方法包括：将实施例1-11和对比例1-6的正极极片压实，从正极极片表面截取固定半径R的圆片，测量其质量M1和厚度H1，截取相同半径的铝箔圆片，测量其质量M2和厚度H2，用质量差除以正极敷料的体积及可得压实密度，压实密度的计算公式如下：
Figure PCTCN2022120833-appb-000001
3)对实施例1-11和对比例1-6的电池进行电化学性能测试，将实施例1-11和对比例1-6的电池在25℃，2.8-4.3V的电压测试区间内，以0.1C恒流恒压充电，截止电流为0.02C，0.1C恒流放电，记录首次充电容量和放电容量，根据以下公式计算电池的参数：放电比容量＝电池首次放电容量(毫安时)/正极材料重量(克)，首次库伦效率＝首次放电容量/首次充电容量， 质量能量密度＝放电比容量(mAh/g)*平均放电电压(V)，体积能量密度＝质量能量密度(Wh/kg)*压实密度(g/cm 3)，测试结果请参阅表1。
表1 实施例1-11和对比例1-6的电池正极材料和电池参数表
Figure PCTCN2022120833-appb-000002
由表1的实验结果可以看出，与对比例1相比，实施例1-4的电池正极材料含有较小粒径的活性颗粒，使制备得到的电池具有较高的质量能量密度，并且实施例1-4的电池体积能量密度相比于对比例1的电池提升幅度为20％，这是由于活性颗粒具有更高的能量密度，且经过颗粒堆积优化后，电池正极材料的压实密度进一步提升，从而提升体积能量密度。
与对比例2和3相比，实施例5-7的电池正极材料具有更高的压实密度，这是由于实施例5-7的电池正极材料磷酸锰铁锂与活性颗粒的质量比较为合适，较小粒径的活性颗粒能有效地填充到磷酸锰铁锂之间的空隙中，产品的压实密度相比对比例2有明显提升；但由于磷酸锰铁锂之间的空隙尺寸有限，故空隙间可填充的颗粒量有一定限度，活性颗粒的量达到一 定值后，反而会降低压实密度，故实施例7的电池正极材料的压实密度相对实施例5有所降低，实验表明当磷酸锰铁锂与活性颗粒的质量比为1:(0.2～0.35)时，电池正极材料能够具有较高的压实密度。除此之外，由于实施例5-7中加入了比容量更高的活性颗粒，故实施例5-7电池的质量能量密度也有所提高。
与对比例4和6相比，实施例8-10电池正极材料中磷酸锰铁锂和活性颗粒的粒径比为3-8，颗粒之间能够实现紧密的堆积。对比例4中磷酸锰铁锂和活性颗粒的粒径差较大，大粒径的磷酸锰铁锂中仍存在较多的空隙，即大颗粒的空隙需要填充更多小颗粒的填充才可实现紧密堆积；对比例5中磷酸锰铁锂和活性颗粒的粒径差较小，活性颗粒无法填充到磷酸锰铁锂的空隙中，导致材料的压实密度降低；对比例6中磷酸锰铁锂的粒径远小于活性颗粒，而磷酸锰铁锂的质量又远大于活性颗粒，导致磷酸锰铁锂的颗粒个数远多于活性颗粒个数，颗粒个数严重失衡，电池正极材料的堆积方式为活性颗粒零零散散地分布在磷酸锰铁锂颗粒当中，无法起到良好的堆积效果，其材料的压实密度低。
实施例11是在一级填充的基础上进行二级填充，二级镍钴锰酸锂能够进一步填充在一级填充后剩余的空隙中，由实验结果可以看出，实施例11与实施例1的正极极片具有更高的压实密度，这说明二级填充可以有效地提高正极极片的压实密度，从而增加电池的质量能量密度和体积能量密度。
由上述实验结果可以看出，通过控制磷酸锰铁锂和活性颗粒的质量比以及粒径分布可以使活性颗粒有效地填充在磷酸锰铁锂的空隙中，从而提高电池正极材料的压实密度，将该电池正极材料制备为正极极片并应用在电池中可以使电池具有较高的质量能量密度和体积能量密度。
以上所述是本申请的示例实施方式，并不能因此而理解为对本申请范围的限制。应当指出，对于本技术领域的普通技术人员来说，在不脱离本申请原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也视为本申请的保护范围。

Claims (19)

  1. 一种电池正极材料，其特征在于，所述电池正极材料包括磷酸锰铁锂颗粒(11)和分散在所述磷酸锰铁锂颗粒(11)间隙中的活性颗粒(12)；所述活性颗粒(12)包括镍钴锰酸锂颗粒、镍钴铝酸锂颗粒、富锂锰基材料颗粒、钴酸锂颗粒、尖晶石锰酸锂LiMn 2O 4颗粒和层状锰酸锂LiMnO 2颗粒中的一种或多种；所述磷酸锰铁锂与所述活性颗粒(12)的中位粒径之比为3～8；所述电池正极材料中，所述磷酸锰铁锂的质量百分含量为70％～90％，所述活性颗粒(12)的质量百分含量为10％～30％。
  2. 如权利要求1所述的电池正极材料，其特征在于，所述磷酸锰铁锂颗粒(11)的中位粒径为2μm-15μm。
  3. 如权利要求1或2所述的电池正极材料，其特征在于，所述活性颗粒(12)的中位粒径为0.5μm-5μm。
  4. 如权利要求1-3任一项所述的电池正极材料，其特征在于，所述活性颗粒(12)包括一级活性颗粒(121)和二级活性颗粒(122)，所述一级活性颗粒(121)的中位粒径为0.5μm-5μm，所述二级活性颗粒(122)的中位粒径为0.1μm-2μm。
  5. 如权利要求1-4任一项所述的电池正极材料，其特征在于，所述磷酸锰铁锂颗粒(11)与所述活性颗粒(12)的质量比为1:(0.2～0.35)。
  6. 如权利要求1-5任一项所述的电池正极材料，其特征在于，所述磷酸锰铁锂颗粒(11)包括LiMn xFe 1-xPO 4，其中，0.5≤x≤0.9。
  7. 如权利要求1-6任一项所述的电池正极材料，其特征在于，所述磷酸锰铁锂颗粒(11)包括碳，所述碳占所述磷酸锰铁锂颗粒(11)的质量百分含量为1％～3％。
  8. 如权利要求1-7任一项所述的电池正极材料，其特征在于，所述磷酸锰铁锂颗粒(11)还包括掺杂元素，所述掺杂元素包括Ti、V、Co、Ni、Cu、Zn、Mg、Ca、Al、Nb、Mo中的一种或多种。
  9. 如权利要求1-8任一项所述的电池正极材料，其特征在于，所述镍钴锰酸锂颗粒包括LiNi aCo bMn 1-a-bO 2，其中，0＜a＜1，0＜b＜1，0＜1-a-b＜1。
  10. 如权利要求1-9任一项所述的电池正极材料，其特征在于，所述镍钴锰酸锂颗粒还包括掺杂元素，所述掺杂元素包括Ti、V、Fe、Cu、Zn、Mg、Ca、Al、Nb、Mo中的一种或多种。
  11. 如权利要求1-10任一项所述的电池正极材料，其特征在于，所述镍钴铝酸锂颗粒包括LiNi mCo nAl 1-m-nO 2，其中，0＜m＜1，0＜n＜1，0＜1-m-n＜1。
  12. 如权利要求1-11任一项所述的电池正极材料，其特征在于，所述镍钴铝酸锂颗粒还包括掺杂元素，所述掺杂元素包括Ti、V、Mn、Fe、Cu、Zn、Mg、Ca、Nb、Mo中的一种或多种。
  13. 如权利要求1-12任一项所述的电池正极材料，其特征在于，所述富锂锰基材料颗粒包括yLi 2MnO 3·(1-y)LiMO 2，其中，0＜y＜1，所述M包括Mn、Ni或Co中至少一种。
  14. 如权利要求1-13任一项所述的电池正极材料，其特征在于，所述富锂锰基材料颗粒还包括掺杂元素，所述掺杂元素包括Ti、V、Fe、Co、Cu、Zn、Mg、Ca、Nb、Mo中的一种或多种。
  15. 如权利要求1-14任一项所述的电池正极材料，其特征在于，所述电池正极材料的压实密度为2.4g/cm 3～3.2g/cm 3。
  16. 如权利要求1-15任一项所述的电池正极材料，其特征在于，所述磷酸锰铁锂颗粒(11)和所述活性颗粒(12)之间无团聚的作用，所述活性颗粒(12)不以包覆形式附着在所述磷酸锰铁锂颗粒(11)的颗粒表面。
  17. 如权利要求1-16任一项所述的电池正极材料，其特征在于，所述活性颗粒(12)相比于所述磷酸锰铁锂颗粒(11)具有更高的压实密度。
  18. 一种正极极片，其特征在于，包括集流体和设置在所述集流体上的正极材料层，所述正极材料层包括如权利要求1-17任一项所述的电池正极材料。
  19. 一种二次电池，其特征在于，包括正极、负极、隔膜和电解液，所述正极包括如权利要求18所述的正极极片。
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US20150349330A1 (en) * 2014-05-29 2015-12-03 Nindge Amperex Technology Limited Positive active material and lithium-ion secondary battery
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US20150349330A1 (en) * 2014-05-29 2015-12-03 Nindge Amperex Technology Limited Positive active material and lithium-ion secondary battery
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