WO2024040829A1 - 正极活性材料、电池及其制备方法 - Google Patents

正极活性材料、电池及其制备方法 Download PDF

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WO2024040829A1
WO2024040829A1 PCT/CN2022/142337 CN2022142337W WO2024040829A1 WO 2024040829 A1 WO2024040829 A1 WO 2024040829A1 CN 2022142337 W CN2022142337 W CN 2022142337W WO 2024040829 A1 WO2024040829 A1 WO 2024040829A1
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active material
nitrate
cathode active
positive electrode
source
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PCT/CN2022/142337
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English (en)
French (fr)
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胡燚
陈巍
欧阳云鹏
谢东
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欣旺达动力科技股份有限公司
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Priority to EP22946052.2A priority Critical patent/EP4350812A1/en
Publication of WO2024040829A1 publication Critical patent/WO2024040829A1/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
    • H01M4/48—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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/66—Nickelates containing alkaline earth metals, e.g. SrNiO3, SrNiO2
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/66—Nickelates containing alkaline earth metals, e.g. SrNiO3, SrNiO2
    • C01G53/68—Nickelates containing alkaline earth metals, e.g. SrNiO3, SrNiO2 containing rare earth, e.g. La1.62 Sr0.38NiO4
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/70—Nickelates containing rare earth, e.g. LaNiO3
    • 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
    • H01M4/13—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
    • H01M4/48—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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/50—Agglomerated particles
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/51—Particles with a specific particle size distribution
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/11—Powder tap density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—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
    • H01M2004/021—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

  • This application relates to the field of new energy technology, specifically a cathode active material, a battery and a preparation method thereof.
  • Batteries such as lithium-ion batteries, have been widely used in various fields due to their advantages such as high specific energy, good power performance, low self-discharge and long cycle life.
  • the cathode active materials used in batteries in electric vehicles are mainly ternary cathode active materials, but their raw materials (such as cobalt sulfate and lithium salts) are expensive.
  • the density can reduce the space occupied by the battery module in the car, which is of positive significance to the lightweight development and cost reduction of new energy vehicles.
  • the use environment of electric vehicle batteries is becoming more and more harsh, especially cold weather, which severely tests the battery performance. Therefore, it is necessary to improve the low-temperature performance of the battery, especially the low-temperature power performance.
  • This application provides a positive active material, a battery and a preparation method thereof, which solves the current problems of poor low-temperature power and low volumetric energy density of batteries prepared with positive active materials.
  • the positive active material includes secondary particles, and the secondary particles have holes.
  • the positive active material satisfies the following characteristics: 4 ⁇ BET ⁇ TD ⁇ (Dv90-Dv10) ⁇ 14, where, BET represents the value of the specific surface area of the cathode active material, in m 2 /g, TD represents the value of the tap density of the cathode active material, in g/cm 3 , and Dv90 represents the cumulative volume distribution percentage of the cathode active material reaching 90%.
  • the value of the corresponding particle diameter when Dv10 represents the value of the corresponding particle diameter when the cumulative volume distribution percentage of the positive active material reaches 10%, in units of ⁇ m.
  • the maximum pore diameter of the positive electrode active material is D max nm, which satisfies: 800 ⁇ D max ⁇ 2200.
  • the half-peak width of the pore size distribution of the cathode active material is DHW nm, which satisfies: 150 ⁇ DHW ⁇ 450 .
  • the porosity P c of the cathode active material satisfies: 45% ⁇ P c ⁇ 75%.
  • the powder compaction density of the cathode active material is P d g/cm 3 and satisfies: 2.8 ⁇ P d ⁇ 3.4.
  • the positive active material includes a compound with the chemical formula Li x Ni y Co z Me k M p O 2 , wherein Me is selected from at least one of Mn or Al, and M includes At least one of Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr or Fe, 0.8 ⁇ x ⁇ 1.1, 0.5 ⁇ y ⁇ 1 , 0 ⁇ z ⁇ 1, 0 ⁇ k ⁇ 1, 0 ⁇ p ⁇ 0.1.
  • the positive active material includes lithium nickel cobalt manganese oxide
  • the lithium nickel cobalt manganese oxide includes nickel element, cobalt element and manganese element, with nickel element, cobalt element and manganese element.
  • the sum of the molar amounts is 1, and the content of nickel element is greater than 0.3.
  • the preparation method of the cathode active material provided according to the second aspect of the present application includes:
  • the ternary material precursor, the M element source and the lithium source are mixed and sintered for the first time. After cooling and crushing, a material containing M element is obtained;
  • the M element-containing material and the coating element source are mixed and sintered for a second time to obtain a positive electrode active material.
  • the cathode active material includes a material with the chemical formula Li x Ni y Co z Me k M p O 2 , wherein Me is selected from at least one of Mn or Al, and M includes At least one of Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr or Fe, 0.8 ⁇ x ⁇ 1.1, 0 ⁇ y ⁇ 1 , 0 ⁇ z ⁇ 1, 0 ⁇ k ⁇ 1, 0 ⁇ p ⁇ 0.1.
  • the nickel source includes at least one of nickel sulfate, nickel acetate or nickel nitrate.
  • the cobalt source includes at least one of cobalt sulfate, cobalt acetate or cobalt nitrate.
  • the manganese source includes at least one of manganese sulfate, manganese acetate or manganese nitrate.
  • the aluminum source includes at least one of aluminum sulfate, aluminum acetate or aluminum nitrate.
  • the M element source includes zirconium nitrate, tungsten nitrate, aluminum nitrate, titanium nitrate, strontium nitrate, magnesium nitrate, yttrium nitrate, cerium nitrate, indium nitrate, niobium nitrate, lanthanum nitrate, At least one of antimony nitrate, vanadium nitrate, zinc nitrate, copper nitrate, chromium nitrate, iron nitrate, tungsten oxide or zirconium oxide.
  • the lithium source includes at least one of lithium hydroxide, lithium carbonate, lithium acetate or lithium nitrate.
  • the coating element source includes one of aluminum nitrate, titanium nitrate, cobalt nitrate, tungsten nitrate, yttrium nitrate, silicon oxide, boron oxide, phosphorus pentoxide or aluminum oxide. or more.
  • the mass percentage of the coating element source in the material containing M element is 0.3wt% ⁇ 0.7wt%.
  • the precipitating agent includes sodium hydroxide solution
  • the complexing agent includes ammonia water
  • the temperature of the first sintering is 600 ⁇ 1000°C, and the time of the first sintering is 3 ⁇ 16 hours.
  • the temperature of the second sintering is 400 ⁇ 700°C, and the time of the second sintering is 1 ⁇ 9 hours.
  • the battery provided according to the third aspect of the present application includes a positive electrode sheet.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector.
  • the positive electrode active material layer includes the above-mentioned positive electrode active material or the above-mentioned preparation method. The prepared cathode active material.
  • the positive active material layer satisfies at least one of the following characteristics:
  • the real active area of the positive active material layer is A cm 2 , which satisfies: 4 ⁇ 10 4 ⁇ A ⁇ 2 ⁇ 10 5 ;
  • PD g/cm 3 represents the compacted density of the positive active material layer, in units; mg represents the weight of the positive active material layer.
  • a and P 0 satisfy: 0.6 ⁇ 1000P 0 /A ⁇ 1.
  • An electrical device provided according to the fourth aspect of the present application includes the above-mentioned battery.
  • the powder compaction density can be effectively increased, thereby improving the compaction ability of the electrode piece and achieving the effect of increasing the volumetric energy density of the battery without deteriorating the power. , circulation and storage gas production and other properties;
  • Figure 1 is an electron microscope characterization test chart of the surface morphology of the cathode active material obtained in Example 2 of the present application;
  • Figure 2 is an electron microscope characterization test diagram of the cross-sectional morphology of the cathode active material obtained in Example 2 of the present application;
  • Figure 3 is a flow chart of a method for preparing a cathode active material provided in an embodiment of the present application.
  • the numerical range displayed using “ ⁇ ” means that the range includes the numerical values described before and after “ ⁇ ” as the minimum value and the maximum value, respectively.
  • the embodiments of the present application provide a cathode active material, a battery and a preparation method thereof. Each is explained in detail below. It should be noted that the order of description of the following embodiments does not limit the preferred order of the embodiments.
  • the first aspect of this application provides a cathode active material.
  • the cathode active material includes secondary particles.
  • the secondary particles have holes.
  • BET represents the value of the specific surface area of the cathode active material, in m 2 /g
  • TD represents the value of the tap density of the cathode active material, in g/cm 3
  • Dv90 represents the cumulative volume of the cathode active material.
  • Dv10 represents the value of the particle size corresponding to the volume cumulative distribution percentage of the positive active material reaching 10%, in ⁇ m.
  • the low-temperature discharge power performance is mainly affected by the positive electrode of the battery. Therefore, this application controls the particle morphology, particle size, particle size distribution, tap density and pore structure of the positive active material to realize the use of the positive active material. The low-temperature power performance and volumetric energy density of the battery are improved.
  • 4.5 ⁇ I ⁇ 11.7 it can be a range of 4.5, 4.8, 5.1, 5.6, 6.1, 6.3, 6.9, 7.3, 7.8, 8.1, 8.6, 9.3, 9.7, 10.5, 11.7 or any two of them.
  • 5.1 ⁇ I ⁇ 9.7 In some embodiments of the present application, 5.6 ⁇ I ⁇ 8.6.
  • the particle morphology, particle size, particle size distribution, tap density and pore structure of the cathode active material are all in an optimal state, which can further improve the low-temperature power performance of the battery and further increase the volume energy of the battery. density.
  • methods to improve the energy density of lithium-ion batteries mainly include increasing the content of nickel in ternary materials, increasing the upper voltage limit, and improving the compaction capacity of the pole pieces.
  • the first two solutions can improve the material Gram capacity can be exerted, but it will lead to varying degrees of battery performance deterioration, such as reduced thermal stability, intensified side reactions with the electrolyte, and increased gas production.
  • the solution of increasing the compaction density of the pole pieces can increase the volume energy of the battery density, but there are problems such as the particles are easily broken, resulting in many interface side reactions, large gas production and poor long-term life. Therefore, this application controls the particle morphology, particle size, particle size distribution, tap density and pore structure of the cathode active material so that the battery has higher energy density and better low-temperature power performance, while ensuring lower gas production and better Good long term performance.
  • 0.4 ⁇ BET ⁇ 3.5 In some embodiments of the present application, 0.4 ⁇ BET ⁇ 3.5. For example, it can be a range of 0.4, 0.8, 1.1, 1.2, 1.4, 1.8, 2.0, 2.3, 2.8, 3.0, 3.5, or any two of these values. In some embodiments of the present application, 0.4 ⁇ BET ⁇ 2.7.
  • the effective contact area between the positive active material and the electrolyte can be better controlled, the side reactions between the positive active material and the electrolyte can be controlled, and the power performance of the battery can be improved.
  • the value of BET can be tested using a specific surface area analyzer (model: Tristar II3020).
  • 1.2 ⁇ TD ⁇ 2.6 In some embodiments of the present application, 1.2 ⁇ TD ⁇ 2.6. For example, it can be a range of 1.2, 1.3, 1.4, 1.5, 1.8, 2.1, 2.2, 2.6, or any two of these values. In some embodiments of the present application, 1.3 ⁇ TD ⁇ 2.2. In some embodiments of the present application, 1.5 ⁇ TD ⁇ 2.1.
  • tap density testing please refer to GB/T5162-2021 Determination of Tap Density of Metal Powders.
  • 4 ⁇ Dv90 ⁇ 18 for example, it can be a range consisting of 4.7, 4.8, 4.9, 5.0, 5.2, 5.4, 5.5, 5.8, 10, 15, or any two values therein. In some embodiments of the present application, 4.9 ⁇ Dv90 ⁇ 15. In some embodiments of the present application, 5.0 ⁇ Dv90 ⁇ 10. 1.5 ⁇ Dv10 ⁇ 6; for example, it can be composed of 1.5, 1.8, 2.1, 2.2, 2.4, 2.5, 2.6, 2.7, 2.8, 5 or any two of them. range. In some embodiments of the present application, 1.5 ⁇ Dv10 ⁇ 5. In some embodiments of the present application, 1.8 ⁇ Dv10 ⁇ 2.8. Controlling appropriate particle size distribution can alleviate the problem of particle breakage during rolling and reduce the occurrence of interfacial side reactions. Dv90, Dv50 and Dv10 were tested using a Malvern laser particle size analyzer.
  • 2 ⁇ Dv50 ⁇ 8, and Dv50 represents the value of the particle size corresponding to when the cumulative volume distribution percentage of the positive active material reaches 50%, in ⁇ m.
  • the maximum pore diameter D max nm of the cathode active material satisfies: 800 ⁇ D max ⁇ 2200; for example, it can be 850, 1100, 1200, 1400, 1500, 1700, 1800, 1900, 2000 or A range consisting of any two values. In some embodiments of the present application, 850 ⁇ D max ⁇ 2000 . In some embodiments of the present application, 1100 ⁇ D max ⁇ 1900 .
  • the pore structure, particle morphology, particle size, particle size distribution, and tap density of the positive active material are controlled in a more appropriate range.
  • the battery has higher energy density and better low-temperature power performance.
  • the half-maximum width D HW nm of the pore size distribution of the cathode active material satisfies: 150 ⁇ D HW ⁇ 450 ; for example, it can be 160, 200, 300, 400, 450, or any two values therein range of composition.
  • 160 ⁇ DHW ⁇ 380 In some embodiments of the present application, 160 ⁇ DHW ⁇ 300 .
  • the porosity P c of the cathode active material satisfies: 45% ⁇ P c ⁇ 75%; for example, it can be 46%, 53%, 54%, 56%, 58%, 62%, 63 %, 65%, 66%, 67%, 72% or a range consisting of any two of these values. In some embodiments of the present application, 53% ⁇ Pc ⁇ 72 %. In some embodiments of the present application, 56% ⁇ Pc ⁇ 67 %.
  • the porosity P c of the positive electrode active material is within the above range, the contact area between the positive electrode active material and the electrolyte can be controlled in a better range, so that the battery has better overall performance.
  • the powder compacted density of the positive active material P d g/cm 3 satisfies: 2.8 ⁇ P d ⁇ 3.4; for example, it can be 2.9, 3.0, 3.1, 3.2, 3.3, or any two of them. A range of values. In some embodiments of the present application, 2.9 ⁇ Pd ⁇ 3.3 .
  • the pore size distribution and porosity of the cathode active material were measured by mercury intrusion method.
  • the compaction density P d is tested with a compaction density meter.
  • the test process can refer to the national standard GB/T 24533-2019. This application controls the material particle morphology, particle size and pore structure to control the specific surface area and porosity of the material, increase the effective contact area between the positive active material and the electrolyte, and optimize ion transmission, electron transmission and the diffusion rate of the electrolyte.
  • the positive active material includes nickel element, cobalt element and Me element. Based on the molar amount of nickel element, cobalt element and Me element being 1, the content of nickel element is greater than or equal to 0.3, where Me At least one selected from Mn or Al.
  • the positive active material includes nickel element, cobalt element and Me element. Based on the molar amount of nickel element, cobalt element and Me element being 1, the content of nickel element is greater than or equal to 0.5, where Me At least one selected from Mn or Al.
  • the cathode active material includes nickel element, cobalt element and Me element. Based on the molar amount of nickel element, cobalt element and Me element being 1, the content of nickel element is less than or equal to 0.7, where Me At least one selected from Mn or Al.
  • the porous cathode active material satisfies 4 ⁇ BET ⁇ TD ⁇ (Dv90-Dv10) ⁇ 14, controlling the nickel element content within the above range can further improve the stability of the cathode active material structure, making the battery more
  • the ion transmission and electron transmission can better alleviate problems such as the reduction of thermal stability, the intensification of side reactions with the electrolyte, and the increase in gas production, so that the battery has better overall performance.
  • the positive active material includes M element
  • the M element includes at least one of Y, Nb, In, La, Zr, Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr or Fe.
  • the cathode active material includes an M element
  • the M element includes at least one of Y, Nb, In, La, Zr or Ce, and includes W, Al, Ti, Sr, Mg, Sb, At least one of V, Zn, Cu, Cr or Fe.
  • the positive active material includes M element, and the M element includes W, and Y, Nb, In, La, Zr, Ce, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, At least one of Cr or Fe.
  • the lithium nickel cobalt manganese oxide contains nickel element, cobalt element and manganese element. Based on the sum of the molar amounts of nickel element, cobalt element and manganese element being 1, the content of nickel element is greater than 0.3.
  • the positive active material includes particles with the chemical formula Li x Ni y Co z Me k M p O 2 , wherein Me is selected from at least one of Mn or Al, and M includes Y, Nb, In, La, Zr, At least one of Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr or Fe, 0.8 ⁇ x ⁇ 1.1, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, 0 ⁇ k ⁇ 1, 0 ⁇ p ⁇ 0.1.
  • the surface of the cathode active material particles also includes a coating material.
  • the coating material includes a coating element, and the coating element includes Al, Ti, Co, W, Y, Si, B, P or F. of at least one.
  • the coating material covers the surface of the positive active material.
  • the coating material is coated on the surface of the positive active material using dry coating (high temperature solid phase method), and the surface of the positive active material is partially or completely covered with a coating layer formed by the coating material, for example, The area of the coating in contact with the positive active material accounts for 50%, 60%, 70%, 80%, 90% or 100% of the surface area of the positive active material. Adding coating material to the surface of the cathode active material to improve the structural stability and rate performance of the cathode active material.
  • the positive active material particles have a surface area and a central area adjacent to the surface area, and the surface area includes at least one of Al, Ti, Co, W, Y, Si, B, P, or F , the central area contains M elements, and M elements contain Zr and W.
  • the central area of the cathode active material contains M elements
  • the surface of the cathode active material contains coating elements, which can make the cathode active material
  • the composition of M elements and coating elements can be adjusted, and better M elements and coating elements can be selected.
  • the coating element can make the structure of the positive active material in a better state and improve the overall performance of the battery.
  • the second aspect of this application provides a method for preparing a cathode active material, as shown in Figure 3, including:
  • This application optimizes the crystal nucleation rate and growth rate by changing process parameters such as pH value, complexing agent concentration, and synthesis atmosphere during the preparation process of the precursor.
  • This application also regulates sintering temperature, sintering time and crushing strength. Since the control of pore structure is very sensitive to the above parameters, multi-stage precise control of the above process parameters is required.
  • the positive active material includes a compound with the chemical formula Li x Ni y Co z Me k M p O 2 , wherein Me is selected from at least one of Mn or Al, and M includes Y, Nb, In, La, Zr, At least one of Ce, W, Al, Ti, Sr, Mg, Sb, V, Zn, Cu, Cr or Fe, 0.8 ⁇ x ⁇ 1.1, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, 0 ⁇ k ⁇ 1, 0 ⁇ p ⁇ 0.1.
  • the nickel source includes at least one of nickel sulfate, nickel acetate or nickel nitrate;
  • the cobalt source includes at least one of cobalt sulfate, cobalt acetate or cobalt nitrate;
  • the manganese source includes manganese sulfate, acetate At least one of manganese or manganese nitrate;
  • the aluminum source includes at least one of aluminum sulfate, aluminum acetate or aluminum nitrate;
  • the M element source includes zirconium nitrate, tungsten nitrate, aluminum nitrate, titanium nitrate, strontium nitrate, magnesium nitrate, nitric acid At least one of yttrium, cerium nitrate, indium nitrate, niobium nitrate, lanthanum nitrate, antimony nitrate, vanadium nitrate, zinc nitrate, copper nitrate, chrom
  • the precipitating agent includes sodium hydroxide solution
  • the complexing agent includes ammonia water
  • the ternary precursor, M element source and lithium source are mixed and sintered.
  • the sintering temperature can be 600 ⁇ 1000°C, 700 ⁇ 900°C, 800 ⁇ 880°C, or 5 ⁇ 50°C. /min to the temperature; the sintering time can be 3 to 16 hours, 5 to 15 hours, or 8 to 10 hours.
  • the material containing the M element and the coating element source are mixed and sintered.
  • the sintering temperature can be 400 ⁇ 700°C, or 450 ⁇ 600°C, or 500 ⁇ 550°C; the sintering time can be 1 ⁇ 9 hours, it can also be 2 ⁇ 8 hours, it can also be 3 ⁇ 7 hours.
  • the preparation method of the positive active material includes;
  • step (2) Mix the precursor obtained in step (1) evenly with the M element source and the lithium source, sinter it in an oxygen atmosphere, cool it to room temperature and then crush it to obtain a material containing M element;
  • a third aspect of the present application provides a battery, including a positive electrode sheet.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector.
  • the positive electrode active material layer includes the above-mentioned positive electrode active material or the above-mentioned positive electrode active material.
  • the positive electrode active material prepared by the preparation method.
  • the real active area of the positive active material layer is A cm 2 , which satisfies: 4 ⁇ 10 4 ⁇ A ⁇ 2 ⁇ 10 5 , for example, it can be 4.5 ⁇ 10 4 , 6.5 ⁇ 10 4 , or 7.6 ⁇ 10 4 , 8 ⁇ 10 4 , 9 ⁇ 10 4 , 1 ⁇ 10 5 or a range consisting of any two of these values.
  • 6.5 ⁇ 10 4 ⁇ A ⁇ 1 ⁇ 10 5 in some embodiments of the present application, 7.6 ⁇ 10 4 ⁇ A ⁇ 9 ⁇ 10 4 ;
  • the real active area refers to the area that can participate The effective area for electrochemical reactions.
  • the real active area of the positive active material layer is related to the pore structure, pore size distribution, specific surface area and pressure resistance of the positive active material. The above material parameters and the compaction density of the positive active material layer work together to cause changes in the real active area.
  • the discharge power per unit volume of the positive active material layer is PW/cm 3 , 8 ⁇ P ⁇ 30; for example, it can be 8.9, 14, 15, 16, 22, 23, 24, 25, 29 or any two of them. In some embodiments of the present application, 8.9 ⁇ P ⁇ 29; in some embodiments of the present application, 15 ⁇ P ⁇ 25.
  • the compacted density of the positive active material layer is PD g/cm 3 , which satisfies: 2.4 ⁇ PD ⁇ 3.5, for example, it can be 2.6, 2.8, 3.0, 3.1, 3.3, or any two values therein. range of composition. In some embodiments of the present application, 2.6 ⁇ Ps ⁇ 3.1 ; the porosity Ps of the positive active material layer satisfies: 20% ⁇ Ps ⁇ 40 %, for example, it can be 22%, 23%, 25%, 26% , 27%, 28%, 30%, 35% or a range consisting of any two values therein. In some embodiments of the present application, 22% ⁇ Ps ⁇ 35 %; in some embodiments of the present application, 25% ⁇ Ps ⁇ 30 %.
  • the above-mentioned positive electrode active material or the positive electrode active material prepared by the above-mentioned method is mixed evenly with a conductive agent, a binder and a solvent, and is made through processes such as sieving, coating, rolling, slitting and cutting. Positive pole piece.
  • the rolling parameters By changing the rolling parameters, the corresponding properties and parameters of the positive electrode piece can also be controlled. As long as the positive active material layer of the present application can be controlled to satisfy the above characteristics.
  • the battery includes a positive electrode piece, a negative electrode piece, a separator film and an electrolyte.
  • the positive electrode piece is the above-mentioned positive electrode piece.
  • the above-mentioned positive electrode sheet, negative electrode sheet, separator, electrolyte, etc. are assembled into a lithium-ion battery.
  • the negative electrode material used in the negative electrode sheet can be one or more of artificial graphite, natural graphite, mesocarbon microspheres, amorphous carbon, lithium titanate or silicon-carbon alloy.
  • the anode material also needs to have the characteristics of high compaction density, high mass specific capacity and high volume specific capacity.
  • the electrolyte includes: an organic solvent.
  • the organic solvent may include chain esters and cyclic esters, and the mass percentage of the chain ester is greater than the mass percentage of the cyclic ester.
  • the cyclic ester may include at least one of ethylene carbonate (EC) or propylene carbonate (PP), and the chain ester may include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) or diethyl carbonate ( DEC) at least one.
  • the solvent of the electrolyte includes EC, EMC, and DEC.
  • the mass ratio of EC, EMC and DEC is (10 ⁇ 25): (10 ⁇ 25):(51 ⁇ 75).
  • the preparation of the electrolyte includes: dissolving fully dry lithium salt in an organic solvent in an argon atmosphere glove box with a water content of ⁇ 10 ppm, and mixing evenly to obtain an electrolyte.
  • the concentration of lithium salt is 0.8 ⁇ 1.3mol/L.
  • the lithium salt may be LiPF 6 (lithium hexafluorophosphate), LiBF 4 (lithium tetrafluoroborate), etc.
  • the preparation of the isolation film includes: selecting a polypropylene film with a thickness of 9 to 18 ⁇ m as the isolation film.
  • a polypropylene film with a thickness of 9 to 18 ⁇ m there is no particular restriction on the isolation membrane, and any well-known porous structure isolation membrane with electrochemical stability and mechanical stability can be used.
  • a fourth aspect of the present application provides an electrical device, including the above-mentioned battery.
  • the electrical device of the present application is, but is not limited to, a backup power supply, a motor, an electric vehicle, an electric motorcycle, a power-assisted bicycle, a bicycle, an electric tool, a large household battery, etc.
  • This embodiment provides a method for preparing a positive active material and a positive electrode sheet.
  • the preparation of positive active materials includes the following steps:
  • the sintering process includes two stages: the first stage is sintering at 600°C for 6 hours; the second stage is sintering at 880°C for 10 hours.
  • the sintering temperature is 450°C and the sintering time is 8 hours to obtain the positive active material.
  • the preparation methods of the positive active materials and positive electrode sheets in Examples 2 to 8, 14 to 18 and Comparative Examples 1 to 3 are generally the same as those in Example 1. The difference is that the positive active materials are changed in Examples 2 to 8 and Comparative Examples 1 to 3. Relevant parameters in the preparation steps, Examples 14 to 18 also changed the nickel-cobalt-manganese ratio, such as pH value, ammonia concentration, synthesis atmosphere and other process parameters, thereby controlling the pore size distribution, porosity and specific surface area of the cathode active material, Obtain the cathode active material with predetermined parameter characteristics, and use such cathode active material to prepare the cathode electrode piece, and obtain the cathode electrode piece with predetermined parameter characteristics.
  • the specific parameters are shown in Table 1 and Table 2. Among them, Comparative Examples 1 to 3 list cases where the specific surface area, pore diameter, and porosity parameters are not within the scope of this application, and they cannot achieve the expected real active area of the cathode active material layer.
  • Examples 19 to 22 use the same cathode active material as Example 1, as well as the same conductive agent and binder. The difference is that Examples 19 to 22 change the rolling parameters in the pole piece preparation process, and control the cathode pole piece.
  • the compaction density can control the porosity and real active area of the positive electrode piece, and obtain the positive electrode piece with predetermined parameter characteristics.
  • the specific parameters are shown in Table 1 and Table 2.
  • Example 9 Compared with Example 1, the difference between Examples 9 to 13 lies in the difference in M elements and coating elements. However, it is ensured that the material pore size distribution, specific surface area and I value are within an appropriate range.
  • the specific material parameters and pole piece parameters are shown in Table 1 and Table 2.
  • test method for the true active area A of the positive active material layer is as follows:
  • the low-temperature power test process is: after the battery is adjusted to 30% SOC, it is operated at a temperature of -20°C. Let it stand for 10 seconds at a certain power P 0 W to stabilize the battery surface temperature. When the terminal voltage is 2.21 ⁇ 2.26V, the test power test is considered successful, that is, P 0 W at this time is the low-temperature discharge power of the battery.
  • the high-temperature storage test process is: charge to 4.3V, store in a 60°C constant temperature box, test the residual capacity every 30 days and re-store with full power; the calculation method is: test the initial capacity Q 0 before storing in the furnace, and every 30 days After a few days, take it out of the incubator, and after cooling, test the remaining capacity Q. “Q/Q 0 ⁇ 100%” is the storage capacity retention rate of the battery.
  • the high-temperature gas production test process is as follows: take 3 battery samples, charge them to 4.3V, store them in a 60°C constant temperature box, and test the battery volume every 15 days using the drainage method. Fully charge 1C every 30 days.
  • the calculation method is: test the initial volume V 0 by drainage method, take out the battery from the thermostat every 15 days, and test the battery volume V by drainage method after cooling. "(V/V 0 -1) ⁇ 100%" is the high temperature storage volume Expansion rate.
  • Examples 1 to 8 and Comparative Examples 1 to 3 compared the material-related parameters of different pore size distributions.
  • the pore diameter D max of the cathode active material increases and the half-peak width of the pore size distribution D HW increases, the porosity P c of the cathode active material increases.
  • the real active area A of the positive active material layer increases, and the low-temperature power performance of the battery is improved.
  • Example 1 Examples 19 to 22, and Examples 14 to 18 compare the relevant parameters of the cathode active material layer with different compactions, as the compaction density of the cathode active material layer and the porosity P s of the cathode active material layer change. , the real active area A of the positive active material layer is affected, and the low-temperature power of the battery is also affected at the same time, indicating that there is a suitable I value, Ps and compaction density that work together to achieve better low-temperature power performance.
  • Example 1 and Examples 9-10 compare the material-related parameters of different M elements.
  • the positive active material contains two M elements, especially when it contains W, the battery has better overall performance than having only one M element. .
  • Example 1 and Examples 11-12 compared the material-related parameters of different coating elements.
  • the modification and substitution of the above coating elements had no obvious impact on the pore size distribution and porosity of the positive active material, and had no obvious impact on the electrical performance of the battery. .
  • Figure 1 shows an electron microscope characterization test diagram of the surface morphology of the cathode active material obtained in Example 2 of the present application
  • Figure 2 shows an electron microscope characterization test of the cross-sectional morphology of the cathode active material obtained in Example 2 of the present application. picture.
  • This application can make the positive active material layer have a higher real active area, increase the effective contact area between the positive active material and the electrolyte, and optimize ion transmission, electron transmission and electrolysis without affecting the processing of the slurry and the positive electrode piece.
  • the diffusion rate of the liquid can be improved to improve the power performance of the battery core, especially the low-temperature power performance.
  • the cathode active material prepared by this application has excellent particle size distribution and compressive strength, which can effectively alleviate the problem of particle breakage during rolling, improve the interface side reactions of the battery, reduce gas production and improve long-term life.
  • the positive active material and positive electrode sheet of the present application have excellent compaction ability, which can ensure the weight of the active material within the unit volume, thereby ensuring the unit volume capacity of the battery.

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Abstract

本申请公开一种正极活性材料、电池及其制备方法。正极活性材料包括多孔二次颗粒，正极活性材料满足如下特征：4≤BET×TD×（Dv90-Dv10）≤14，其中，BET表示正极活性材料的比表面积的值，单位为m 2/g，TD表示正极活性材料的振实密度的值，单位为g/cm 3，Dv90表示正极活性材料的体积累计分布百分数达到90％时对应的粒径的值，单位为μm，Dv10表示正极活性材料的体积累计分布百分数达到10％时对应的粒径的值，单位为μm。本申请通过控制正极活性材料的颗粒形貌、尺寸和孔结构，实现低温功率性能的提升；并且通过合理控制正极活性材料的颗粒形貌、粒度分布以及振实密度，达到提高电池体积能量密度的效果。

Description

正极活性材料、电池及其制备方法
本申请要求于2022年08月23日提交中国专利局、申请号为202211010331.4、发明名称为“正极活性材料、电池及其制备方法”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
本申请涉及新能源技术领域，具体涉及一种正极活性材料、电池及其制备方法。
 背景技术
电池，例如锂离子电池由于具有比能量高、功率性能好、自放电低和循环寿命长等优点，已被广泛应用于各个领域。目前电动汽车中的电池所用的正极活性材料主要是三元正极活性材料，但其原材料（例如硫酸钴和锂盐）的价格昂贵，为进一步降低电动汽车的成本，通过提高锂离子电池的体积能量密度，可减小电池模组在汽车上的空间占比，对新能源汽车的轻量化发展和降低成本具有积极意义。且电动汽车电池的使用环境越来越苛刻，尤其是寒冷天气对电池性能发挥带来严重考验，因此需要提高电池的低温性能，特别是低温功率性能。
发明内容
 技术问题
本申请提供一种正极活性材料、电池及其制备方法，解决了目前正极活性材料所制备的电池低温功率不佳，体积能量密度较低的问题。
 技术解决方案
根据本申请第一方面提供的正极活性材料，正极活性材料包括二次颗粒，二次颗粒上有孔，正极活性材料满足如下特征：4≤BET×TD×（Dv90-Dv10）≤14，其中，BET表示正极活性材料的比表面积的值，单位为m 2/g，TD表示正极活性材料的振实密度的值，单位为g/cm 3，Dv90表示正极活性材料的体积累计分布百分数达到90％时对应的粒径的值，单位为μm，Dv10表示正极活性材料的体积累计分布百分数达到10％时对应的粒径的值，单位为μm。
可选的，在本申请的其它实施例中，0.4≤BET≤3.5；1.2≤TD≤2.6；4≤Dv90≤18；1.5≤Dv10≤6。
可选的，在本申请的其它实施例中，正极活性材料的孔径最大值为D max nm，满足：800≤D max≤2200。
可选的，在本申请的其它实施例中，正极活性材料的孔径分布的半峰宽为D HW nm，满足：150≤D HW≤450。
可选的，在本申请的其它实施例中，正极活性材料的孔隙率P c满足：45%≤P c≤75%。
可选的，在本申请的其它实施例中，正极活性材料的粉体压实密度为P d g/cm 3，满足：2.8≤P d≤3.4。
可选的，在本申请的其它实施例中，正极活性材料包括化学式为Li xNi yCo zMe kM pO 2的化合物，其中，Me选自Mn或Al中的至少一种，M包含Y、Nb、In、La、Zr、Ce、W、Al、Ti、Sr、Mg、Sb、V、Zn、Cu、Cr或Fe中的至少一种，0.8≤x≤1.1，0.5＜y＜1，0＜z＜1，0＜k＜1，0≤p≤0.1。
可选的，在本申请的其它实施例中，正极活性材料包含锂镍钴锰氧化物，锂镍钴锰氧化物中包含镍元素、钴元素和锰元素，以镍元素、钴元素和锰元素的摩尔量之和为1计，镍元素的含量大于0.3。
根据本申请第二方面提供的正极活性材料的制备方法，包括：
将锰源或铝源的任意一种与镍源、钴源混合，加入沉淀剂和络合剂，反应得到三元材料前驱体；
将三元材料前驱体、M元素源和锂源混合并进行第一次烧结，冷却并破碎后得到含M元素的材料；
将含M元素的材料和包覆元素源混合并进行第二次烧结，得到正极活性材料。
可选的，在本申请的其它实施例中，正极活性材料包含化学式为Li xNi yCo zMe kM pO 2的材料，其中，Me选自Mn或Al中的至少一种，M包含Y、Nb、In、La、Zr、Ce、W、Al、Ti、Sr、Mg、Sb、V、Zn、Cu、Cr或Fe中的至少一种，0.8≤x≤1.1，0＜y＜1，0＜z＜1，0＜k＜1，0≤p≤0.1。
可选的，在本申请的其它实施例中，镍源包括硫酸镍、醋酸镍或硝酸镍中的至少一种。
可选的，在本申请的其它实施例中，钴源包括硫酸钴、醋酸钴或硝酸钴中的至少一种。
可选的，在本申请的其它实施例中，锰源包括硫酸锰、醋酸锰或硝酸锰中的至少一种。
可选的，在本申请的其它实施例中，铝源包括硫酸铝、醋酸铝或硝酸铝中的至少一种。
可选的，在本申请的其它实施例中，M元素源包括硝酸锆、硝酸钨、硝酸铝、硝酸钛、硝酸锶、硝酸镁、硝酸钇、硝酸铈、硝酸铟、硝酸铌、硝酸镧、硝酸锑、硝酸钒、硝酸锌、硝酸铜、硝酸铬、硝酸铁、氧化钨或氧化锆中的至少一种。
可选的，在本申请的其它实施例中，锂源包括氢氧化锂、碳酸锂、醋酸锂或硝酸锂中的至少一种。
可选的，在本申请的其它实施例中，包覆元素源包括硝酸铝、硝酸钛、硝酸钴、硝酸钨、硝酸钇、氧化硅、氧化硼、五氧化二磷或氧化铝中的一种或多种。
可选的，在本申请的其它实施例中，包覆元素源占所述含M元素的材料的质量百分比为0.3wt%~0.7wt%。
可选的，在本申请的其它实施例中，沉淀剂包括氢氧化钠溶液，络合剂包括氨水。
可选的，在本申请的其它实施例中，第一次烧结的温度为600~1000℃，第一次烧结的时间为3~16小时。
可选的，在本申请的其它实施例中，第二次烧结的温度为400~700℃，第二次烧结的时间为1~9小时。
根据本申请第三方面提供的电池，包括正极极片，正极极片包括正极集流体和设置于正极集流体上的正极活性材料层，正极活性材料层包括上述的正极活性材料或上述的制备方法所制备的正极活性材料。
可选的，在本申请的其它实施例中，正极活性材料层满足如下特征中的至少一者:
（i）正极活性材料层的真实活性面积为A cm 2，满足：4×10 4≤A≤2×10 5；
（ii）正极活性材料层的压实密度PD g/cm 3，满足：2.4≤PD≤3.5；
（iii）正极活性材料层的孔隙率P s满足：20%≤P s≤40%；
（iv）当温度为-20℃，所述电池荷电状态为30%时，所述正极活性材料层的单位体积放电功率为P W/cm 3，8≤P≤30，P=P 0×PD/m，P 0 W表示电池在所述条件下的放电功率；PD g/cm 3表示正极活性材料层压实密度，单位为；mg表示正活性材料层重量。
可选的，A与P 0满足：0.6≤1000P 0/A≤1。
根据本申请第四方面提供的用电装置，包括上述电池。
 有益效果
根据本申请实施例的正极活性材料，至少具有如下技术效果：
1）通过合理控制正极活性材料的颗粒形貌、粒度分布以及振实密度，有效提升粉体压实密度，从而改善极片压实能力，达到提高电池体积能量密度的效果，且不会恶化功率、循环和存储产气等性能；
2）通过控制正极活性材料的颗粒形貌、颗粒尺寸和孔结构，从而控制材料的比表面积和孔隙率，提高正极活性材料与电解液的有效接触面积，优化离子传输、电子传输以及电解液的扩散速率，实现电池功率性能的提升，尤其是低温功率性能的提升。
 附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本申请实施例2得到的正极活性材料的表面形貌的电镜表征测试图；
图2是本申请实施例2得到的正极活性材料的截面形貌的电镜表征测试图；
图3是本申请实施例提供的正极活性材料的制备方法的流程图。
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。
本说明书中，使用“～”来显示的数值范围，表示包含以在“～”前后记载的数值分别作为最小值和最大值的范围。
本申请实施例提供一种正极活性材料、电池及其制备方法。以下分别进行详细说明。需说明的是，以下实施例的描述顺序不作为对实施例优选顺序的限定。
本申请第一方面提供一种正极活性材料，正极活性材料包括二次颗粒，二次颗粒上有孔，正极活性材料的I值满足如下特征：4≤I=BET×TD×（Dv90-Dv10）≤14，其中，BET表示正极活性材料的比表面积的值，单位为m 2/g，TD表示正极活性材料的振实密度的值，单位为g/cm 3，Dv90表示正极活性材料的体积累计分布百分数达到90％时对应的粒径的值，单位为μm，Dv10表示正极活性材料的体积累计分布百分数达到10％时对应的粒径的值，单位为μm。低温放电功率性能主要是受电池的正极极片的影响，因此本申请通过控制正极活性材料的颗粒形貌、颗粒尺寸、粒度分布、振实密度和孔结构，实现利用该正极活性材料所制得的电池的低温功率性能以及体积能量密度的提升。
在本申请的一些实施例中，4.5≤I≤11.7。例如可以为4.5、4.8、5.1、5.6、6.1、6.3、6.9、7.3、7.8、8.1、8.6、9.3、9.7、10.5、11.7或其中任意两个数组成的范围。在本申请的一些实施例中，5.1≤I≤9.7。在本申请的一些实施例中，5.6≤I≤8.6。当I的值在此范围内，正极活性材料的颗粒形貌、颗粒尺寸、粒度分布、振实密度和孔结构均处于较优状态，能进一步改善电池的低温功率性能，进一步提高电池的体积能量密度。
目前在材料和电池设计层面，提高锂离子电池能量密度的方法主要包括提高三元材料中镍元素的含量、提高电压上限和提高极片的压实能力等方式，前两种方案虽然可以提高材料的克容量发挥，但会导致电池性能不同程度的恶化，例如热稳定性降低、与电解液副反应加剧和产气量增加等问题，提高极片的压实密度的方案虽然可以提高电池的体积能量密度，但存在颗粒易破碎，导致界面副反应多，产气量大和长期寿命差等问题。因此本申请通过控制正极活性材料的颗粒形貌、颗粒尺寸、粒度分布、振实密度和孔结构使电池具有较高的能量密度和较好的低温功率性能，同时保证较低的产气量和较好的长期性能。
在本申请的一些实施例中，0.4≤BET≤3.5。例如可以为0.4、0.8、1.1、1.2、1.4、1.8、2.0、2.3、2.8、3.0、3.5或其中任意两个值组成的范围。在本申请的一些实施例中，0.4≤BET≤2.7。通过控制正极活性材料的BET在此，可以更好的控制正极活性材料与电解液的有效接触面积，控制正极活性材料与电解液的副反应，提高电池的功率性能。BET的值可采用比表面积分析仪（型号：Tristar Ⅱ3020）进行测试。
在本申请的一些实施例中，1.2≤TD≤2.6。例如可以为1.2、1.3、1.4、1.5、1.8、2.1、2.2、2.6或其中任意两个值组成的范围。在本申请的一些实施例中，1.3≤TD≤2.2。在本申请的一些实施例中，1.5≤TD≤2.1。通过合理控制正极活性材料的振实密度，有效提升粉体压实密度，从而改善正极极片压实能力，达到提高电池体积能量密度的效果。振实密度测试可参考GB/T5162-2021 金属粉末振实密度的测定。
在本申请的一些实施例中，4≤Dv90≤18；例如可以为4.7、4.8、4.9、5.0、5.2、5.4、5.5、5.8、10、15或其中任意两个值组成的范围。在本申请的一些实施例中，4.9≤Dv90≤15。在本申请的一些实施例中，5.0≤Dv90≤10。1.5≤Dv10≤6；例如可以为1.5、1.8、2.1、2.2、2.4、2.5、2.6、2.7、2.8、5或其中任意两个值组成的范围。在本申请的一些实施例中，1.5≤Dv10≤5。在本申请的一些实施例中，1.8≤Dv10≤2.8。控制合适的粒度分布，可缓解辊压过程中颗粒破碎的问题，减少界面副反应的发生。Dv90、Dv50和Dv10采用马尔文激光粒度仪进行测试。
在本申请的一些实施例中，2≤Dv50≤8，Dv50表示正极活性材料的体积累计分布百分数达到50％时对应的粒径的值，单位为μm。
在本申请的一些实施例中，正极活性材料的孔径最大值D max nm，满足：800≤D max≤2200；例如可以为850、1100、1200、1400、1500、1700、1800、1900、2000或其中任意两个值组成的范围。在本申请的一些实施例中，850≤D max≤2000。在本申请的一些实施例中，1100≤D max≤1900。当I的值在上述范围的同时，正极活性材料的孔径最大值满足上述条件时，正极活性材料的孔的结构、颗粒形貌、颗粒尺寸、粒度分布、振实密度控制在更合适的范围，使电池具有较高的能量密度和较好的低温功率性能。
在本申请的一些实施例中，正极活性材料的孔径分布的半峰宽D HW nm，满足：150≤D HW≤450；例如可以为160、200、300、400、450或其中任意两个值组成的范围。在本申请的一些实施例中，160≤D HW≤380。在本申请的一些实施例中，160≤D HW≤300。
在本申请的一些实施例中，正极活性材料的孔隙率P c满足：45%≤P c≤75%；例如可以为46%、53%、54%、56%、58%、62%、63%、65%、66%、67%、72%或其中任意两个值组成的范围。在本申请的一些实施例中，53%≤P c≤72%。在本申请的一些实施例中，56%≤P c≤67%。当正极活性材料的孔隙率P c在上述范围内，能使正极活性材料与电解液的接触面积控制在更优的范围，使电池具有更优的综合性能。
在本申请的一些实施例中，正极活性材料的粉体压实密度P d g/cm 3，满足：2.8≤P d≤3.4；例如可以为2.9、3.0、3.1、3.2、3.3或其中任意两个值组成的范围。在本申请的一些实施例中，2.9≤P d≤3.3。
其中，正极活性材料的孔径分布和孔隙率通过压汞法测得。压实密度P d为压实密度仪进行测试，测试过程可参考国标GB/T 24533-2019。本申请通过控制材料颗粒形貌、颗粒尺寸和孔结构，从而控制材料的比表面积和孔隙率，提高正极活性材料与电解液的有效接触面积，优化离子传输、电子传输以及电解液的扩散速率，实现电池功率性能的提升，尤其是低温功率性能的提升；通过控制正极活性材料合适的粒度分布和抗压强度，可有效缓解辊压过程中颗粒破碎的问题，改善电池的界面副反应，降低产气量和改善长期寿命。
在本申请的一些实施例中，正极活性材料包含镍元素、钴元素和Me元素，以镍元素、钴元素和Me元素的摩尔量为1计，镍元素的含量大于或等于0.3，其中，Me选自Mn或Al中的至少一种。
在本申请的一些实施例中，正极活性材料包含镍元素、钴元素和Me元素，以镍元素、钴元素和Me元素的摩尔量为1计，镍元素的含量大于或等于0.5，其中，Me选自Mn或Al中的至少一种。
在本申请的一些实施例中，正极活性材料包含镍元素、钴元素和Me元素，以镍元素、钴元素和Me元素的摩尔量为1计，镍元素的含量小于或等于0.7，其中，Me选自Mn或Al中的至少一种。当多孔的正极活性材料在满足4≤BET×TD×（Dv90-Dv10）≤14的基础上，控制镍元素含量在在上述范围内能够进一步改善正极活性材料结构的稳定性，使电池具有更优的离子传输、电子传输，可以更好的减缓热稳定性降低、与电解液副反应加剧和产气量增加等问题，使电池具有更优的综合性能。
在本申请的一些实施例中，正极活性材料包含M元素， M元素包含Y、Nb、In、La、Zr、Ce、W、Al、Ti、Sr、Mg、Sb、V、Zn、Cu、Cr或Fe中的至少一种。
在本申请的一些实施例中，正极活性材料包含M元素，M元素包含Y、Nb、In、La、Zr或Ce中的至少一种，且包含W、Al、Ti、Sr、Mg、Sb、V、Zn、Cu、Cr或Fe中的至少一种。
在本申请的一些实施例中，正极活性材料包含M元素，M元素包含W，以及Y、Nb、In、La、Zr、Ce、Al、Ti、Sr、Mg、Sb、V、Zn、Cu、Cr或Fe中的至少一种。
进一步的，锂镍钴锰氧化物中包含镍元素、钴元素和锰元素，以镍元素、钴元素和锰元素的摩尔量之和为1计，镍元素的含量大于0.3。
进一步的，正极活性材料包括化学式为Li xNi yCo zMe kM pO 2的颗粒，其中，Me选自Mn或Al中的至少一种，M包含Y、Nb、In、La、Zr、Ce、W、Al、Ti、Sr、Mg、Sb、V、Zn、Cu、Cr或Fe中的至少一种，0.8≤x≤1.1，0＜y＜1，0＜z＜1，0＜k＜1，0≤p≤0.1。
在本申请的一些实施例中，正极活性材料颗粒表面还包括包覆材料，包覆材料包括包覆元素，包覆元素包含Al、Ti、Co、W、Y、Si、B、P或F中的至少一种。包覆材料包覆在正极活性材料表面。具体的，采用干法包覆（高温固相法）将包覆材料包覆在正极活性材料表面，正极活性材料的表面部分或全部包覆有包覆材料所形成的包覆层，例如，包覆层与正极活性材料接触的面积占正极活性材料表面积的50%、60%、70%、80%、90%或100%。在正极活性材料表面增加包覆材料，以提高正极活性材料的结构稳定性和倍率性能。
在本申请的一些实施例中，正极活性材料颗粒具有表面区域，以及邻接表面区域的中心区域，表面区域包含Al、Ti、Co、W、Y、Si、B、P或F中的至少一种，中心区域包含M元素，M元素包含Zr和W。在多孔正极活性材料满足4≤I=BET×TD×（Dv90-Dv10）≤14的同时，正极活性材料的中心区域包含M元素的同时在正极活性材料表面包含包覆元素，能够使正极活性材料用于正极极片时具有较优的颗粒形貌、颗粒尺寸使正极活性材料在正极极片能够具有较好的分布，同时调整M元素和包覆元素的组成，选择更优的M元素和包覆元素，能够使正极活性材料的结构处于更优状态，使电池的综合性能更优。
相应的，本申请第二方面提供一种正极活性材料的制备方法，如图3所示，包括：
S1：将锰源或铝源的任意一种与镍源、钴源混合，加入沉淀剂和络合剂，反应得到三元材料前驱体；
S2：将三元材料前驱体、M元素源和锂源混合并进行第一次烧结，冷却并破碎后得到包含M元素的材料；
S3：将包含M元素的材料和包覆元素源混合并进行第二次烧结，得到正极活性材料。
本申请通过改变前驱体制备过程中的pH值、络合剂浓度和合成气氛等工艺参数，优化晶体成核速率和生长速率。本申请还调控烧结温度、烧结时间和破碎强度。由于孔隙结构的调控对以上参数非常敏感，因此需要对上述工艺参数做多阶段的精准调控。
进一步的，正极活性材料包含化学式为Li xNi yCo zMe kM pO 2的化合物，其中，Me选自Mn或Al中的至少一种，M包含Y、Nb、In、La、Zr、Ce、W、Al、Ti、Sr、Mg、Sb、V、Zn、Cu、Cr或Fe中的至少一种，0.8≤x≤1.1，0＜y＜1，0＜z＜1，0＜k＜1，0≤p≤0.1。
在本申请的一些实施例中，镍源包括硫酸镍、醋酸镍或硝酸镍中的至少一种；钴源包括硫酸钴、醋酸钴或硝酸钴中的至少一种；锰源包括硫酸锰、醋酸锰或硝酸锰中的至少一种；铝源包括硫酸铝、醋酸铝或硝酸铝中的至少一种；M元素源包括硝酸锆、硝酸钨、硝酸铝、硝酸钛、硝酸锶、硝酸镁、硝酸钇、硝酸铈、硝酸铟、硝酸铌、硝酸镧、硝酸锑、硝酸钒、硝酸锌、硝酸铜、硝酸铬、硝酸铁、氧化钨或氧化锆中的至少一种；锂源包括氢氧化锂、碳酸锂、醋酸锂或硝酸锂中的至少一种；包覆元素源包括硝酸铝、硝酸钛、硝酸钴、硝酸钨、硝酸钇、氧化硅、氧化硼、五氧化二磷或氧化铝中的至少一种。
在本申请的一些实施例中，沉淀剂包括氢氧化钠溶液，络合剂包括氨水。
进一步的，将三元前驱体、M元素源和锂源混合并烧结，烧结的温度可以为600~1000℃，也可以为700~900℃，还可以为800~880℃，以5~50℃/min的速率升温至该温度；烧结的时间可以为3~16小时，也可以为5~15小时，还可以为8~10小时。
进一步的，将包含M元素的材料和包覆元素源混合并烧结，烧结的温度可以为400~700℃，也可以为450~600℃，还可以为500~550℃；烧结的时间可以为1~9小时，也可以为2~8小时，还可以为3~7小时。
具体实施时，正极活性材料的制备方法包括;
（1）按一定摩尔比例称取镍源、钴源、锰源或铝源的任意一种，分别溶于去离子水中，通过控制氨水浓度、pH值、搅拌速度、反应时间和反应温度等工艺条件合成前驱体，例如可以控制pH值为10~13；
（2）将步骤（1）所得的前驱体与M元素源以及锂源混合均匀，在氧气气氛下进行烧结，冷却至室温后破碎，得到包含M元素的材料；
（3）将包含M元素的材料和包覆元素源混合均匀，在空气气氛下400~700℃烧结1~9h，得到正极活性材料。
此外，本申请第三方面提供一种电池，包括正极极片，正极极片包括正极集流体和设置于正极集流体上的正极活性材料层，正极活性材料层包括上述的正极活性材料或上述的制备方法所制备的正极活性材料。
在本申请的一些实施例中，正极活性材料层的真实活性面积为A cm 2，满足：4×10 4≤A≤2×10 5，例如可以为4.5×10 4、6.5×10 4、7.6×10 4、8×10 4、9×10 4、1×10 5或其中任意两个值组成的范围。在本申请的一些实施例中，6.5×10 4≤A≤1×10 5；在本申请的一些实施例中，7.6×10 4≤A≤9×10 4；真实活性面积指的是可参与电化学反应的有效面积。正极活性材料层的真实活性面积与正极活性材料的孔结构、孔径大小分布、比表面积以及抗压能力有关，以上材料参数和正极活性材料层压实密度共同作用会引起真实活性面积的变化。
在本申请的一些实施例中，当温度为-20℃，电池荷电状态SOC为30%时，正极活性材料层的单位体积放电功率为P W/cm 3，8≤P≤30；例如可以为8.9、14、15、16、22、23、24、25、29或其中任意两个值组成的范围。在本申请的一些实施例中，8.9≤P≤29；在本申请的一些实施例中，15≤P≤25。电池的低温低SOC放电功率P0与真实活性面积A的关系满足：0.6≤1000P 0/A≤1，d，P=P 0×PD/m，P 0W表示电池在所述条件下的放电功率；PD g/cm 3表示正极活性材料层压实密度；mg表示正活性材料层重量。
在本申请的一些实施例中，正极活性材料层的压实密度为PD g/cm 3，满足：2.4≤PD≤3.5，例如可以为2.6、2.8、3.0、3.1、3.3或其中任意两个值组成的范围。在本申请的一些实施例中，2.6≤P s≤3.1；正极活性材料层的孔隙率P s满足：20%≤P s≤40%，例如可以为22%、23%、25%、26%、27%、28%、30%、35%或其中任意两个值组成的范围。在本申请的一些实施例中，22%≤P s≤35%；在本申请的一些实施例中，25%≤P s≤30%。
具体实施时，将上述的正极活性材料或上述方法制得的正极活性材料，与导电剂、粘结剂以及溶剂搅拌均匀，经过过筛、涂布、辊压、分条和裁片等工序制成正极极片。通过改变辊压参数，也可以控制正极极片的相应性质和参数。只要能够控制本申请的正极活性材料层满足上述特征即可。
具体的，电池包括正极极片、负极极片、隔离膜和电解液，正极极片为上述的正极极片。具体实施时，将上述的正极极片，与负极极片、隔离膜和电解液等组装成锂离子电池。其中负极极片所采用的负极材料可以为人造石墨、天然石墨、中间相碳微球、无定形碳、钛酸锂或硅碳合金中的一种或多种。负极材料也需要具备压实密度高、质量比容量和体积比容量较高等特点。
在一些实施例中，电解液包括：有机溶剂，有机溶剂可以包含链状酯和环状酯，链状酯的质量百分含量大于环状酯的质量百分含量。环状酯可以包含碳酸乙烯酯（EC）或碳酸丙烯酯（PP）中的至少一者，链状酯可以包含碳酸二甲酯（DMC）、碳酸甲乙酯（EMC）或碳酸二乙酯（DEC）中的至少一者。在一些实施例中，电解液的溶剂包括EC、EMC和DEC。在一些实施例中EC、EMC和DEC的质量比为(10~25): (10~25):(51~75)。在一些实施例中，电解液的制备包括：在含水量<10ppm的氩气气氛手套箱中，将充分干燥的锂盐溶解于有机溶剂中，混合均匀，获得电解液。其中，锂盐的浓度为0.8~1.3mol/L。
在一些实施例中，锂盐可以为LiPF 6（六氟磷酸锂）、LiBF 4（四氟硼酸锂）等。
在一些实施例中，隔离膜的制备包括：选用厚度为9~18μm厚的聚丙烯膜作为隔离膜。对隔离膜没有特别的限制，可以选用任意公知的具有电化学稳定性和机械稳定性的多孔结构隔离膜。
本申请第四方面提供一种用电装置，包括上述的电池。
在一些实施例中，本申请的用电装置为，但不限于备用电源、电机、电动汽车、电动摩托车、助力自行车、自行车、电动工具、家庭用大型蓄电池等。
下面结合具体实施例进行说明。
实施例1、
本实施例提供正极活性材料和正极极片的制备方法。
正极活性材料制备包括如下步骤：
1）按元素摩尔比Ni：Co：Mn=0.5:0.2:0.3的比例称取硫酸镍、硫酸钴和硫酸锰分别溶于去离子水中，将各金属溶液通过管道输送到反应釜形成混合金属溶液，并通入氮气作为保护气，在混合金属溶液中加入NaOH水溶液作为沉淀剂，加入氨水作为络合剂，分阶段调节溶液的氨水浓度和溶液pH值，反应10小时，得到前驱体。
2）将前驱体、碳酸锂、氧化钨和氧化锆混合均匀，控制锂配比为1.1:1，氧化钨和氧化锆与前驱体的重量占比分别为0.6wt%、0.37wt%。
3）将混合好的物料转入烧结工序，烧结工序包括两个阶段：第一阶段在600℃下烧结6小时；第二阶段在880℃下烧结10小时。
4）对烧结完后的材料进行破碎，然后将破碎后的材料与氧化铝混合均匀，氧化铝与破碎后的材料的重量占比为0.5wt%。
5）将混合好的物料转入烧结工序，烧结温度为450℃，烧结时间为8小时，得到正极活性材料。
6）将正极活性材料、导电剂、粘结剂按照质量比97:1.5:1.5进行混合，之后与溶剂搅拌混合均匀，经过过筛、涂布、辊压、分条和裁片等工序，制得正极极片。得到的正极活性材料参数和正极极片参数值具体如表1和表2所示。
实施例2~8，14~18和对比例1~3中正极活性材料和正极极片的制备方法大致同实施例1，区别在于，实施例2~8和对比例1~3改变正极活性材料制备步骤中的相关参数，实施例14~18还改变了镍钴锰比例，例如pH值、氨水浓度和合成气氛等工艺参数，由此可控制正极活性材料的孔径分布、孔隙率和比表面积，获得具有预定参数特性的正极活性材料，应用此类正极活性材料制备正极极片，可获得具有预定参数特征的正极极片，具体参数见表1和表2。其中，对比例1~3列举了比表面积、孔径及孔隙率参数不在本申请的范围内的情况，其不能达到预期的正极活性材料层真实活性面积。
实施例19~22采用与实施例1相同的正极活性材料，以及相同的导电剂和粘结剂，区别在于，实施例19~22改变极片制备工序中的辊压参数，通过控制正极极片的压实密度，可控制正极极片的孔隙率和真实活性面积，获得具有预定参数特征的正极极片，具体参数见表1和表2。
实施例9~13与实施例1相比，差异在于M元素和包覆元素的不同，但保证材料孔径分布、比表面积和I值在适当的范围，具体材料参数和极片参数见表1和表2。
其中正极活性材料层的真实活性面积A测试方法如下：
1）将电池调至指定SOC（例如30%SOC）；
2）将调好SOC的电池转至手套箱中拆解，用对称电池的制样模具裁剪正极极片进行制样（正极极片样品尺寸为46 x28mm），倒入适量高纯无水碳酸二甲酯DMC浸泡清洗，每8小时更换一次DMC，连续清洗3次，将干燥12小时之后的正极极片制作对称电池；
3）将对称电池进行EIS测试，根据EIS测试曲线（奈奎斯特图）读出最大半径对应的频率f，根据公式ω max=2πf，计算得到角速度ω max；
4）对对称电池EIS进行拟合，得到电荷转移阻抗R ct的具体数值；
5）利用公式A=1/20ω maxR ct进行计算，得到电极真实活性面积A。
表1
表2
对实施例1~22和对比例1~3的锂离子电池进行低温功率、高温存储和高温产气测试，低温功率测试流程为：将电池调至30% SOC后，在-20℃的温度条件下静置，使电池表面温度稳定，以一定功率P 0 W 放电10s，末端电压为2.21~2.26V时，认为试功率测试成功，即此时的P 0 W为电池的低温放电功率。高温存储测试流程为：充电至4.3V，置于60℃恒温箱中存储，每隔30天测试残余容量并重新满电存储；计算方法为：入炉存储之前测试初始容量Q 0，每隔30天之后从温箱取出，冷却后，测试残余容量Q，“Q/Q 0×100%”即电池的存储容量保持率。高温产气测试流程为：取3个电池样品，充电至4.3V，置于60℃恒温箱中存储，每隔15天用排水法测试电池体积。每隔30天1C满充一次。计算方法为：排水法测试初始体积V 0，每隔15天从温箱取出电池，冷却后用排水法测试电池体积V，“（V/V 0-1）×100%”即为高温存储体积膨胀率。
性能数据如表3所示：
表3
实施例1~8和对比例1~3对比了不同孔径分布的材料相关参数，随着正极活性材料的孔径D max增大和孔径分布半峰宽D HW增大，正极活性材料的孔隙率P c增大，再经过相同的电极和电池制作工艺，正极活性材料层的真实活性面积A增大，电池的低温功率性能提升。
实施例1和实施例19~22，以及实施例14~18对比了不同压密的正极活性材料层的相关参数，随着正极活性材料层压实密度和正极活性材料层孔隙率P s的改变，正极活性材料层的真实活性面积A均受到影响，电池的低温功率也同时受到影响，说明存在一个合适的I值、Ps和压实密度共同作用使低温功率性能发挥较优。
实施例1和实施例9~10对比了不同M元素的材料相关参数，当正极活性材料M元素为两种，尤其含有W时，相比于只有一种M元素，电池具有更优的综合性能。
实施例1和实施例11-12对比了不同包覆元素的材料相关参数，以上包覆元素的更改替换，对正极活性材料的孔径分布和孔隙率没有明显影响，对电池的电性能没有明显影响。
如图1所示为本申请实施例2得到的正极活性材料的表面形貌的电镜表征测试图；如图2所示为本申请实施例2得到的正极活性材料的截面形貌的电镜表征测试图。
本申请可在不影响浆料和正极极片加工的前提下，使正极活性材料层具有较高的真实活性面积，提高正极活性材料与电解液的有效接触面积，优化离子传输、电子传输以及电解液的扩散速率，实现电芯功率性能的提升，尤其是低温功率性能的提升。本申请制得的正极活性材料具有较优的粒度分布和抗压强度，可有效缓解辊压过程中颗粒破碎的问题，改善电池的界面副反应，降低产气量和改善长期寿命。本申请的正极活性材料和正极极片具有较优的压实能力，可保证单位体积内的活性物质重量，从而保证电池的单位体积容量。
以上对本申请所提供的一种正极活性材料、电池及其制备方法进行了详细介绍，本文中应用了具体个例对本申请的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本申请的方法及其核心思想；同时，对于本领域的技术人员，依据本申请的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本申请的限制。

Claims (15)

  1. 一种正极活性材料，其特征在于，包括二次颗粒，所述二次颗粒上有孔，所述正极活性材料满足如下特征：
    4≤BET×TD×（Dv90-Dv10）≤14，
    其中，BET表示所述正极活性材料的比表面积的值，单位为m 2/g，
    TD表示所述正极活性材料的振实密度的值，单位为g/cm 3，Dv90表示所述正极活性材料的体积累计分布百分数达到90％时对应的粒径的值，单位为μm，Dv10表示所述正极活性材料的体积累计分布百分数达到10％时对应的粒径的值，单位为μm。
  2. 根据权利要求1所述的正极活性材料，其特征在于，0.4≤BET≤3.5；1.2≤TD≤2.6；4≤Dv90≤18；1.5≤Dv10≤6。
  3. 根据权利要求1所述的正极活性材料，其特征在于，所述正极活性材料的孔径最大值为D max nm，满足：800≤D max≤2200。
  4. 根据权利要求1所述的正极活性材料，其特征在于，所述正极活性材料的孔径分布的半峰宽为D HWnm，满足：150≤D HW≤450。
  5. 根据权利要求1所述的正极活性材料，其特征在于，所述正极活性材料的孔隙率P c满足：45%≤P c≤75%。
  6. 根据权利要求1所述的正极活性材料，其特征在于，所述正极活性材料的粉体压实密度为P d g/cm 3，满足：2.8≤P d≤3.4。
  7. 根据权利要求1~6中任一项所述的正极活性材料，其特征在于，所述正极活性材料包括化学式为Li xNi yCo zMe kM pO 2的化合物，其中，Me选自Mn或Al中的至少一种，M包含Y、Nb、In、La、Zr、Ce、W、Al、Ti、Sr、Mg、Sb、V、Zn、Cu、Cr或Fe中的至少一种，0.8≤x≤1.1，0＜y＜1，0＜z＜1，0＜k＜1，0≤p≤0.1。
  8. 根据权利要求1所述的正极活性材料，其特征在于，所述正极活性材料包含锂镍钴锰氧化物，所述锂镍钴锰氧化物包含镍元素、钴元素和锰元素，以所述镍元素、所述钴元素和所述锰元素的摩尔量之和为1计，所述镍元素的含量大于0.3。
  9. 一种如权利要求1~8中任一项所述的正极活性材料的制备方法，其特征在于，包括：
    将锰源或铝源的任意一种与镍源、钴源混合，加入沉淀剂和络合剂，反应得到三元材料前驱体；
    将所述三元材料前驱体、M元素源和锂源混合并进行第一次烧结，冷却并破碎后得到含M元素的材料；
    将所述含M元素的材料和包覆元素源混合并进行第二次烧结，得到所述正极活性材料。
  10. 根据权利要求9所述的正极活性材料的制备方法，其特征在于，所述镍源包括硫酸镍、醋酸镍或硝酸镍中的至少一种；所述钴源包括硫酸钴、醋酸钴或硝酸钴中的至少一种；所述锰源包括硫酸锰、醋酸锰或硝酸锰中的至少一种；所述铝源包括硫酸铝、醋酸铝或硝酸铝中的至少一种；所述M元素源包括硝酸锆、硝酸钨、硝酸铝、硝酸钛、硝酸锶、硝酸镁、硝酸钇、硝酸铈、硝酸铟、硝酸铌、硝酸镧、硝酸锑、硝酸钒、硝酸锌、硝酸铜、硝酸铬、硝酸铁、氧化钨或氧化锆中的至少一种；所述锂源包括氢氧化锂、碳酸锂、醋酸锂或硝酸锂中的至少一种；所述包覆元素源包括硝酸铝、硝酸钛、硝酸钴、硝酸钨、硝酸钇、氧化硅、氧化硼、五氧化二磷或氧化铝中的一种或多种。
  11. 根据权利要求9~10中任一项所述的正极活性材料的制备方法，其特征在于，所述包覆元素源占所述含M元素的材料的质量百分比为0.3wt%~0.7wt%；所述沉淀剂包括氢氧化钠溶液，所述络合剂包括氨水。
  12. 根据权利要求9~10中任一项所述的正极活性材料的制备方法，其特征在于，所述第一次烧结的温度为600~1000℃，所述第一次烧结的时间为3~16小时；所述第二次烧结的温度为400~700℃，所述第二次烧结的时间为1~9小时。
  13. 一种电池，包括正极极片，其特征在于，所述正极极片包括正极集流体和设置于所述正极集流体上的正极活性材料层，所述正极活性材料层包括如权利要求1~8中任一项所述的正极活性材料或如权利要求9~12中任一项所述的制备方法制得的正极活性材料。
  14. 根据权利要求13所述的电池，其特征在于，所述正极活性材料层满足如下特征中的至少一者：
    （i）所述正极活性材料层的真实活性面积为A cm 2，满足：4×10 4≤A≤2×10 5；
    （ii）所述正极活性材料层的压实密度为PDg/cm 3，满足：2.4≤PD≤3.5；
    （iii）所述正极活性材料层的孔隙率P s满足：20%≤P s≤40%；
  15. 一种用电装置，其特征在于，包含权利要求14所述的电池。
PCT/CN2022/142337 2022-08-23 2022-12-27 正极活性材料、电池及其制备方法 WO2024040829A1 (zh)

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