WO2024065157A1 - 正极活性材料及其制备方法、正极极片、二次电池、电池模块、电池包和用电装置 - Google Patents

正极活性材料及其制备方法、正极极片、二次电池、电池模块、电池包和用电装置 Download PDF

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WO2024065157A1
WO2024065157A1 PCT/CN2022/121607 CN2022121607W WO2024065157A1 WO 2024065157 A1 WO2024065157 A1 WO 2024065157A1 CN 2022121607 W CN2022121607 W CN 2022121607W WO 2024065157 A1 WO2024065157 A1 WO 2024065157A1
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positive electrode
boron
active material
electrode active
cobalt
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PCT/CN2022/121607
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English (en)
French (fr)
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沈重亨
桓书星
吴奇
陈强
柳娜
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/121607 priority Critical patent/WO2024065157A1/zh
Publication of WO2024065157A1 publication Critical patent/WO2024065157A1/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
    • 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
    • H01M4/36—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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of lithium batteries, and in particular to a positive electrode active material and a preparation method thereof, and a positive electrode sheet, a secondary battery, a battery module, a battery pack and an electrical device comprising the positive electrode active material.
  • lithium-ion batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • lithium-ion batteries have made great progress, higher requirements have been put forward for their energy density, cycle performance and safety performance.
  • Positive electrode materials are an important component of lithium-ion batteries.
  • common positive electrode materials include layered structure materials (such as lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, etc.), spinel structure materials, polyanion materials, and high-nickel positive electrode materials.
  • High-nickel positive electrode materials have attracted more and more attention due to their high energy density, low cost, and reliable safety.
  • high-nickel positive electrode materials have significantly improved energy density compared with other materials, as the nickel content increases, the thermal decomposition temperature of the material decreases, resulting in poor cycle stability and thermal stability. Therefore, the service life of the battery cell is short and there are safety risks, which to a certain extent hinders the further development of high-nickel positive electrode materials. Therefore, it is necessary to adopt certain strategies to optimize high-nickel positive electrode materials, so as to improve the high-temperature storage performance and safety performance of the battery while increasing the energy density of the battery.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode active material, which has a high compaction density, improved high-temperature storage performance and safety performance, and to provide a preparation method of the positive electrode active material, as well as a positive electrode sheet, a secondary battery, a battery module, a battery pack and an electrical device containing the positive electrode active material.
  • the first aspect of the present application provides a positive electrode active material, the positive electrode active material comprises a base material and a coating layer located on the surface of the base material, wherein:
  • the coating layer is a boron-containing ternary alloy or a boron-containing ternary alloy oxide.
  • the present application at least includes the following beneficial effects: 1)
  • the positive electrode active material of the present application has good dispersibility, high filling degree between particles, good material processing performance, high compaction density, and can effectively improve the energy density of the battery; 2)
  • the positive electrode active material of the present application has improved surface structure stability, thereby improving the high temperature storage performance and safety performance of the battery.
  • the boron-containing ternary alloy is as shown in Formula I B-X1-X2 (I), wherein X1 and X2 are independently selected from one of the following elements: cobalt, hafnium, niobium, titanium, zirconium, tungsten, aluminum, molybdenum, copper, and the boron-containing ternary alloy oxide is as shown in Formula II B-Y1-Y2-O (II), wherein Y1 and Y2 are independently selected from one of the following elements: cobalt, hafnium, niobium, titanium, zirconium, tungsten, aluminum, molybdenum, copper.
  • the coating layer is the boron-containing ternary alloy shown in Formula I or the boron-containing ternary alloy oxide shown in Formula II, the surface structural stability of the material can be improved, thereby improving the high-temperature storage performance and safety performance of the battery.
  • the positive electrode active material satisfies: 1.30 ⁇ (Dv90-Dv10)/Dv50 ⁇ 2.10.
  • the positive electrode active material has good dispersibility, high filling degree between particles, good material processing performance, and high compaction density, so that the battery obtains high energy density.
  • the amount of the coating layer is 500ppm-20000ppm, and optionally, the amount of the coating layer is 4000-15000ppm, based on the weight of the base material.
  • the amount of the coating layer is within the above range, the surface structure stability of the high-nickel material can be effectively improved, thereby improving the high temperature storage performance and safety performance of the battery.
  • the boron-containing ternary alloy is selected from at least one of the following: boron-cobalt-hafnium, boron-cobalt-niobium, boron-cobalt-titanium, boron-cobalt-zirconium, boron-cobalt-tungsten, boron-cobalt-aluminum, boron-cobalt-molybdenum, boron-cobalt-copper, boron-hafnium-titanium.
  • the boron-containing ternary alloy is selected from at least one of the following: boron-cobalt-hafnium, boron-cobalt-niobium, boron-cobalt-titanium, boron-cobalt-tungsten, boron-cobalt-aluminum, boron-hafnium-titanium.
  • the above-mentioned boron-containing ternary alloy is selected for surface and grain boundary coating, the surface structural stability of the material can be improved, thereby improving the high temperature storage performance and safety performance of the battery.
  • the boron-containing ternary alloy oxide is selected from at least one of the following: boron-cobalt-hafnium oxide, boron-cobalt-niobium oxide, boron-cobalt-titanium oxide, boron-cobalt-zirconium oxide, boron-cobalt-tungsten oxide, boron-cobalt-aluminum oxide, boron-cobalt-molybdenum oxide, boron-cobalt-copper oxide, boron-hafnium-titanium oxide, optionally, the boron-containing ternary alloy oxide is selected from at least one of the following: boron-cobalt-hafnium oxide, boron-cobalt-niobium oxide, boron-cobalt-titanium oxide, boron-cobalt-tungsten oxide, boron-cobalt-aluminum oxide, boron-hafnium-titanium oxide, optionally
  • the molar ratio of boron, X1 and X2 in the boron-containing ternary alloy is 1:0.5:0.04-1:5:4, optionally 1:0.5:0.15-1:1:0.4.
  • the surface structure stability of the material can be improved, thereby improving the high temperature storage performance and safety performance of the battery.
  • the molar ratio of boron, Y1 and Y2 in the boron-containing ternary alloy oxide is 1:0.5:0.03-1:5:5, optionally 1:0.5:0.15-1:1:0.4.
  • the surface structure stability of the material can be improved, thereby improving the high temperature storage performance and safety performance of the battery.
  • the Dv50 of the positive electrode active material is 6 ⁇ m-18 ⁇ m, optionally 9 ⁇ m-13 ⁇ m.
  • the compaction density of the positive electrode active material can be optimized, so that the battery can obtain high energy density.
  • the compaction density of the positive electrode active material under 5 tons (ie, 5T) pressure is 3.65-3.75 g/cm 3.
  • the positive electrode active material has a high compaction density and a high filling degree between particles, which is not only conducive to improving the processing performance of the positive electrode active material, but also can effectively improve the energy density of the battery.
  • the second aspect of the present application provides a method for preparing the positive electrode active material of the first aspect of the present application, comprising:
  • the positive electrode active material prepared by the above method has good dispersibility, high filling degree between particles, good material processing performance, high compaction density, and improved surface structure stability.
  • the secondary battery prepared thereby has improved high temperature storage performance and safety performance.
  • the boron-containing compound is selected from one or more of cobalt boride, hafnium boride, niobium boride, titanium boride, zirconium boride, tungsten boride, aluminum boride, molybdenum boride and copper boride
  • the metal element is selected from one or more of cobalt, hafnium, niobium, titanium, zirconium, tungsten, aluminum, molybdenum and copper
  • the metal oxide is selected from one or more of cobalt oxide, hafnium oxide, niobium oxide, titanium oxide, zirconium oxide, tungsten oxide, aluminum oxide, molybdenum oxide and copper oxide.
  • the (Dv90-Dv10)/Dv50 of the matrix material obtained in step S1) is ⁇ 1.2, and optionally, (Dv90-Dv10)/Dv50 is ⁇ 1.25.
  • the distribution of the matrix material meets the above range, a positive electrode active material with good dispersibility, high inter-particle filling degree and good material processing performance can be obtained.
  • the base material, the boron-containing compound and the metal element are mixed under an inert atmosphere, and sintered under an inert atmosphere at a sintering temperature of 300-700°C, optionally 300-550°C, and a sintering time of 3-10h, optionally 5-10h.
  • a positive electrode active material coated with a boron-containing ternary alloy can be obtained, thereby improving the surface structural stability of the material and improving the high temperature storage performance and safety performance of the battery.
  • the base material, the boron-containing compound and the metal oxide are sintered in an oxygen atmosphere at a sintering temperature of 300-700°C, optionally 550-650°C, and a sintering time of 3-10 hours, optionally 3-8 hours.
  • a positive electrode active material coated with a boron-containing ternary alloy oxide can be obtained, thereby improving the surface structural stability of the material and improving the high temperature storage performance and safety performance of the battery.
  • the mass ratio of the intermediate material to water is 1:1-1:5, the water washing time is 1-10 min, the vibration frequency of the vibration drying is 10-50 Hz, and the drying time is 2-8 h.
  • the third aspect of the present application provides a positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a first positive electrode active material, the first positive electrode active material being the positive electrode active material of the first aspect of the present application or the positive electrode active material prepared by the method of the second aspect of the present application, and the content of the first positive electrode active material in the positive electrode film layer is 10% by weight or more, based on the total weight of the positive electrode film layer.
  • the processing performance of the electrode sheet can be improved.
  • the positive electrode film layer further includes a second positive electrode active material
  • the quantity ratio of the first positive electrode active material to the second positive electrode active material is 6:4-8:2, optionally 6.5:3.5-7.5:2.5
  • the chemical formula of the second positive electrode active material is LiNi x Co y Mn z Ma M'b O 2
  • M at least one of Zr, Y, Al, Ti, W, Sr, Ta, Sb, Nb, Na, K, Ca or Ce
  • the Dv50 of the second positive electrode active material is 2 ⁇ m-5 ⁇ m, optionally 2.5 ⁇ m-3.5 ⁇ m.
  • the tap density of the second positive electrode active material is ⁇ 1.8 g/cm 3 , and optionally 1.2-1.5 g/cm 3 .
  • the processing performance of the pole piece can be further improved.
  • the fourth aspect of the present application provides a secondary battery, which includes the positive electrode plate of the third aspect of the present application.
  • a fifth aspect of the present application provides a battery module, which includes the secondary battery of the fourth aspect of the present application.
  • a sixth aspect of the present application provides a battery pack, which includes the battery module of the fifth aspect of the present application.
  • the seventh aspect of the present application provides an electrical device comprising at least one selected from the secondary battery of the fourth aspect of the present application, the battery module of the fifth aspect of the present application, or the battery pack of the sixth aspect of the present application.
  • the battery module, battery pack and electric device of the present application include the secondary battery provided by the present application, and therefore have at least the same advantages as the secondary battery.
  • FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .
  • FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.
  • “Scope” disclosed in the present application is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range.
  • the scope defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just the abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), which means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application represent open-ended or closed-ended expressions.
  • the “include” and “comprising” may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • the material In order to maintain its electrical neutrality, the material is prone to form new phases and pores on the surface, resulting in unstable structure of high-nickel cathode materials. Under overcharge conditions, the structural instability is accelerated, because it is accompanied by partial structural transformation to spinel and NiO rock salt phases, and oxygen is generated, which poses certain risks to the safety of the battery.
  • the electrochemical properties of high-nickel cathode materials are usually improved by surface coating, ion doping and other means.
  • the oxygen evolution that occurs when high-nickel cathode materials are used in cycles not only oxidizes the organic electrolyte and forms gas, but also leads to cation reduction and/or densification, which may initiate other degradation processes in a chain reaction.
  • the present application provides a positive electrode active material, the positive electrode active material comprising a base material and a coating layer located on the surface of the base material, wherein:
  • the coating layer is a boron-containing ternary alloy or a boron-containing ternary alloy oxide.
  • the positive active material provided by the present application realizes the double coating effect on the surface and grain boundary of the base material through the boron-containing ternary alloy or the boron-containing ternary alloy oxide, greatly improves the stability of the material surface structure, and thus improves the storage stability and safety of the material; on the other hand, the positive active material of the present application has good dispersibility, high filling degree between particles, good material processing performance, high compaction density, and can effectively improve the energy density of the battery.
  • the base material is a secondary particle composed of primary particles
  • the boron-containing ternary alloy or the boron-containing ternary alloy oxide is formed by high-quality wetting and construction with the base material to form a close combination and comprehensive coverage, which is not only coated on the surface of the secondary particles, but also located at the grain boundary position of the primary particles, realizing a full range of coating on the surface and grain boundary position of the polycrystalline base material, which can alleviate the intergranular stress corrosion cracking, microstructural degradation and side reactions on the positive side, and the cross effect of transition metals on the negative electrode, greatly reducing the gas production of the material, making the structure of the positive active material more stable, and the thermal stability and safety are also significantly improved, thereby improving the high temperature storage performance and safety performance of the material.
  • the above-mentioned limitation on the numerical range of a is not only a limitation on the stoichiometric number of each element as M, but also a limitation on the sum of the stoichiometric numbers of each element as M.
  • the stoichiometric numbers a1, a2...an of M1, M2...Mn must each fall within the numerical range of a defined in the present application, and the sum of a1, a2...an must also fall within the numerical range; for the case where M' is more than two elements, the limitation on the numerical range of the stoichiometric number of M' in the present application also has the above-mentioned meaning.
  • Dv10 is the particle size corresponding to when the cumulative volume percentage of the sample reaches 10%
  • Dv50 is the particle size corresponding to when the cumulative volume percentage of the sample reaches 50%
  • Dv90 is the particle size corresponding to when the cumulative volume percentage of the sample reaches 90%.
  • the dispersibility of the material can be calculated by (Dv90-Dv10)/Dv50.
  • the boron-containing ternary alloy is as shown in Formula I B-X1-X2 (I), wherein X1 and X2 are independently selected from one of the following elements: cobalt, hafnium, niobium, titanium, zirconium, tungsten, aluminum, molybdenum, copper, and the boron-containing ternary alloy oxide is as shown in Formula II B-Y1-Y2-O (II), wherein Y1 and Y2 are independently selected from one of the following elements: cobalt, hafnium, niobium, titanium, zirconium, tungsten, aluminum, molybdenum, copper.
  • the coating layer is the boron-containing ternary alloy shown in Formula I or the boron-containing ternary alloy oxide shown in Formula II, the surface structural stability of the material can be improved, thereby improving the high-temperature storage performance and safety performance of the battery.
  • the positive electrode active material satisfies: 1.30 ⁇ (Dv90-Dv10)/Dv50 ⁇ 2.10.
  • the positive electrode active material has good dispersibility, high filling degree between particles, good material processing performance, and high compaction density, so that the battery obtains high energy density.
  • the amount of the coating layer is 500ppm-20000ppm, optionally, the amount of the coating layer is 4000-15000ppm, based on the weight of the base material.
  • the amount of the coating layer can be 500ppm, 2000ppm, 4000ppm, 10000ppm, 15000ppm, 17000ppm or 20000ppm.
  • the amount of the coating layer is within the above range, it can play a coating role of uniformly wetting the surface and grain boundaries of the material, improve the surface structural stability of the material, and thus improve the high temperature storage performance and safety performance of the battery.
  • the amount of the coating layer is too little, the material cannot be well coated, and the surface structural stability of the material cannot be effectively improved; if the amount of the coating layer is too much, island accumulation will be formed, resulting in a decrease in the gram capacity of the material and an increase in the DCR of the battery cell.
  • the boron-containing ternary alloy is selected from at least one of the following: boron-cobalt-hafnium, boron-cobalt-niobium, boron-cobalt-titanium, boron-cobalt-zirconium, boron-cobalt-tungsten, boron-cobalt-aluminum, boron-cobalt-molybdenum, boron-cobalt-copper, boron-hafnium-titanium.
  • the boron-containing ternary alloy is selected from at least one of the following: boron-cobalt-hafnium, boron-cobalt-niobium, boron-cobalt-titanium, boron-cobalt-tungsten, boron-cobalt-aluminum, boron-hafnium-titanium.
  • the above-mentioned boron-containing ternary alloy is selected for surface and grain boundary coating, the surface structural stability of the material can be improved, thereby improving the high temperature storage performance and safety performance of the battery.
  • the boron-containing ternary alloy oxide is selected from at least one of the following: boron-cobalt-hafnium oxide, boron-cobalt-niobium oxide, boron-cobalt-titanium oxide, boron-cobalt-zirconium oxide, boron-cobalt-tungsten oxide, boron-cobalt-aluminum oxide, boron-cobalt-molybdenum oxide, boron-cobalt-copper oxide, boron-hafnium-titanium oxide, optionally, the boron-containing ternary alloy oxide is selected from at least one of the following: boron-cobalt-hafnium oxide, boron-cobalt-niobium oxide, boron-cobalt-titanium oxide, boron-cobalt-tungsten oxide, boron-cobalt-aluminum oxide, boron-hafnium-titanium oxide, optionally
  • the molar ratio of boron, X1 and X2 in the boron-containing ternary alloy is 1:0.5:0.04-1:5:4, optionally 1:0.5:0.15-1:1:0.4.
  • the surface structure stability of the material can be improved, thereby improving the high temperature storage performance and safety performance of the battery.
  • the molar ratio of boron, Y1 and Y2 in the boron-containing ternary alloy oxide is 1:0.5:0.03-1:5:5, optionally 1:0.5:0.15-1:1:0.4.
  • the surface structure stability of the material can be improved, thereby improving the high temperature storage performance and safety performance of the battery.
  • the Dv50 of the positive electrode active material is 6 ⁇ m-18 ⁇ m, optionally 9 ⁇ m-13 ⁇ m.
  • the compaction density of the positive electrode active material can be optimized, so that the battery can obtain high energy density.
  • the compaction density of the positive electrode active material at a pressure of 5T is 3.65-3.75 g/cm 3.
  • the positive electrode active material has a high compaction density and a high filling degree between particles, which is not only beneficial to further improve the processing performance of the positive electrode active material, but also can further improve the energy density of the battery.
  • the compaction density can be measured according to GB/T 24533-2009.
  • the second aspect of the present application provides a method for preparing the positive electrode active material of the first aspect of the present application, comprising:
  • the matrix material is a secondary particle composed of primary particles.
  • the boron-containing compound or the boron-containing ternary alloy oxide is not only completely coated on the surface of the secondary particles, but also injected into the grain boundary position of the primary particles under the strong drive of the interfacial chemical reaction, that is, the double coating effect of the surface and the grain boundary is realized simultaneously, which greatly improves the stability of the surface structure of the material, and thus improves the storage stability and safety of the material.
  • the boron-containing compound is selected from one or more of cobalt boride, hafnium boride, niobium boride, titanium boride, zirconium boride, tungsten boride, aluminum boride, molybdenum boride and copper boride
  • the metal element is selected from one or more of cobalt, hafnium, niobium, titanium, zirconium, tungsten, aluminum, molybdenum and copper
  • the metal oxide is selected from one or more of cobalt oxide, hafnium oxide, niobium oxide, titanium oxide, zirconium oxide, tungsten oxide, aluminum oxide, molybdenum oxide and copper oxide.
  • the method for preparing high-nickel positive electrode materials known in the art can be used to prepare the matrix material of the present application, that is, the lithium source, the high-nickel hydroxide precursor, and the dopant are mixed, and then sintered at 650-850°C in an oxygen atmosphere to obtain the matrix material of the present application.
  • the matrix material obtained in step S1) has (Dv90-Dv10)/Dv50 ⁇ 1.2, and optionally, (Dv90-Dv10)/Dv50 ⁇ 1.25.
  • the distribution of the matrix material meets the above range, a positive electrode active material with good dispersibility, high inter-particle filling degree and good material processing performance can be obtained.
  • the base material, the boron-containing compound and the metal element are mixed under an inert atmosphere, and sintered under an inert atmosphere at a sintering temperature of 300-700°C, optionally 300-550°C, and a sintering time of 3-10h, optionally 5-10h.
  • a positive electrode active material coated with a boron-containing ternary alloy can be obtained, thereby improving the surface structural stability of the material and improving the high temperature storage performance and safety performance of the battery.
  • the base material, the boron-containing compound and the metal oxide are sintered in an oxygen atmosphere at a sintering temperature of 300-700°C, optionally 550-650°C, and a sintering time of 3-10 hours, optionally 3-8 hours.
  • the mass ratio of the intermediate material to water is 1: 1-1: 5
  • the washing time is 1-10min
  • the vibration frequency of the vibration drying is 10-50Hz
  • the drying time is 2-8h.
  • the vibration drying can be carried out on, for example, a WZG series horizontal vibration dryer, and the vibration frequency can be, for example, more than 10Hz, more than 15Hz, more than 20Hz, more than 30Hz or more than 50Hz, and the drying time can be, for example, more than 2h, more than 3h, more than 4h, more than 5h, more than 6h, more than 7h or more than 8h.
  • step S3 Through the vibration drying of step S3), the large block cut angles on the secondary particles can be peeled off, which broadens the material particle size distribution, makes the positive active material have good dispersibility, high filling degree between particles, good material processing performance, high compaction density, and can effectively improve the energy density of the battery.
  • the third aspect of the present application provides a positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a first positive electrode active material, the first positive electrode active material being the positive electrode active material of the first aspect of the present application or the positive electrode active material prepared by the method of the second aspect of the present application, and the content of the first positive electrode active material in the positive electrode film layer is 10% by weight or more, based on the total weight of the positive electrode film layer.
  • the positive electrode active material obtained by using the first aspect of the present application or the preparation method of the second aspect of the present application has good dispersibility and high inter-particle filling, thereby improving the processing performance of the electrode sheet.
  • the positive electrode film layer further includes a second positive electrode active material
  • the quantity ratio of the first positive electrode active material to the second positive electrode active material is 6:4-8:2, optionally 6.5:3.5-7.5:2.5
  • the chemical formula of the second positive electrode active material is LiNi x Co y Mn z Ma M' b O 2
  • M at least one of Zr, Y, Al, Ti, W, Sr, Ta, Sb, Nb, Na, K, Ca or Ce
  • the Dv50 of the second positive electrode active material is 2 ⁇ m-5 ⁇ m, optionally 2.5 ⁇ m-3.5 ⁇ m.
  • the small particles of the second positive electrode active material can effectively fill the pores of the large particles of the first positive electrode active material, thereby further improving the processing performance of the sheet.
  • the tap density of the second positive electrode active material is ⁇ 1.8 g/cm 3 , optionally 1.2-1.5 g/cm 3 .
  • the processing performance of the pole piece can be further improved.
  • the powder compaction density of the first positive electrode material and the second positive electrode material at 5T is 3.71-3.83 g/cm 3 .
  • a secondary battery is provided.
  • a secondary battery typically includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.
  • active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet.
  • the electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet.
  • the separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
  • the battery group margin is 90-95%.
  • the positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes the positive electrode active material of the first aspect of the present application.
  • the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil may be used.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material is the positive electrode active material of the first aspect of the present application or the positive electrode active material obtained by the method of the second aspect of the present application.
  • the weight ratio of the positive electrode active material in the positive electrode film layer is 80-100 weight %, based on the total weight of the positive electrode film layer.
  • the positive electrode active material adopts the positive electrode active material of the first aspect of the present application as the first positive electrode material, and the following positive electrode active material is additionally adopted as the second positive electrode active material:
  • the mass ratio of the first positive electrode active material to the second positive electrode active material is 8.5:1.5-5:5.
  • the weight ratio of the positive electrode active material in the positive electrode film layer is 80-100 weight %, based on the total weight of the positive electrode film layer.
  • the positive electrode film layer may also optionally include a binder.
  • the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • the weight ratio of the binder in the positive electrode film layer is 0-20% by weight, based on the total weight of the positive electrode film layer.
  • the positive electrode film layer may further include a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the weight ratio of the conductive agent in the positive electrode film layer is 0-20 weight %, based on the total weight of the positive electrode film layer.
  • the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; wherein the positive electrode slurry has a solid content of 40-80% by weight, and the viscosity at room temperature is adjusted to 5000-25000 mPa ⁇ s, and the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained, the positive electrode powder coating unit area density is 150-350 mg/m 2 , and the positive electrode sheet compaction density is 3.0-3.6 g/cm 3 , and can be optionally 3.3-3.5 g/cm 3.
  • the calculation formula of the compaction density is:
  • Compacted density coating surface density/(thickness of the electrode after extrusion - thickness of the current collector).
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the metal foil copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode active material may adopt the negative electrode active material for the battery known in the art.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material and lithium titanate.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compound, silicon carbon compound, silicon nitrogen compound and silicon alloy.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compound and tin alloy.
  • the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode active material may have an average particle size (D 10 ) of 1 ⁇ m-15 ⁇ m, preferably 4 ⁇ m-9 ⁇ m, an average particle size (D 50 ) of 12 ⁇ m-22 ⁇ m, preferably 14 ⁇ m-17 ⁇ m, and an average particle size (D 90 ) of 26 ⁇ m to 40 ⁇ m, preferably 30 ⁇ m-37 ⁇ m.
  • D10 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 10%
  • D50 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 50%
  • D90 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 90%.
  • the weight ratio of the negative electrode active material in the negative electrode film layer is 70-100 weight%, based on the total weight of the negative electrode film layer.
  • the negative electrode film layer may further include a binder.
  • the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • PAAS sodium polyacrylate
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • PMAA polymethacrylic acid
  • CMCS carboxymethyl chitosan
  • the negative electrode film layer may further include a conductive agent.
  • the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the weight ratio of the conductive agent in the negative electrode film layer is 0-20 weight %, based on the total weight of the negative electrode film layer.
  • the negative electrode film layer may further include other additives, such as a thickener (such as sodium carboxymethyl cellulose (CMC-Na)), etc.
  • a thickener such as sodium carboxymethyl cellulose (CMC-Na)
  • the weight ratio of the other additives in the negative electrode film layer is 0-15% by weight, based on the total weight of the negative electrode film layer.
  • the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry, wherein the solid content of the negative electrode slurry is 30-70% by weight, and the viscosity at room temperature is adjusted to 2000-10000 mPa ⁇ s; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • the negative electrode powder coating unit area density is 75-220 mg/m 2
  • the negative electrode sheet compaction density is 1.2-2.0 g/m 3 .
  • the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
  • the present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.
  • the electrolyte can be liquid, gel or all-solid.
  • the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.
  • the concentration of the electrolyte salt is typically 0.5-5 mol/L.
  • the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • additives such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the secondary battery further includes a separator.
  • the present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer can be the same or different, without particular limitation.
  • the isolation film has a thickness of 6-40 ⁇ m, and optionally 12-20 ⁇ m.
  • the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.
  • the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • FIG1 is a secondary battery 5 of a square structure as an example.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 52.
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries may be assembled into a battery module.
  • the number of secondary batteries contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG3 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a housing space, and the plurality of secondary batteries 5 are housed in the housing space.
  • the battery modules described above may also be assembled into a battery pack.
  • the battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.
  • FIG4 and FIG5 are battery packs 1 as an example.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 to form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device.
  • the electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • a secondary battery, a battery module or a battery pack may be selected according to its usage requirements.
  • Fig. 6 is an example of an electric device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • a battery pack or a battery module may be used.
  • a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the positive electrode slurry was coated on the surface of an aluminum foil with a thickness of 12 ⁇ m, and after drying and cold pressing, a positive electrode sheet was obtained.
  • the positive electrode active material loading of the sheet was 21.5 mg/ cm2 .
  • [Negative electrode sheet] Mix the negative electrode active material artificial graphite, hard carbon, conductive agent acetylene black, binder styrene butadiene rubber (SBR), tackifier lithium montmorillonite, and thickener sodium carboxymethyl cellulose (CMC-Na) in deionized water at a weight ratio of 90:5:2:2:1, apply it on copper foil, dry it, and cold press it to obtain a negative electrode sheet.
  • the coating amount is 0.015g/ cm2
  • the compaction density is 1.65g/ cm3 .
  • Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1, and then LiPF6 was uniformly dissolved in the above solution to obtain an electrolyte, wherein the concentration of LiPF6 was 1 mol/L.
  • isolation membrane The isolation membrane is purchased from Cellgard, model number is cellgard 2400.
  • the positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is between the positive and negative electrode sheets to play an isolating role, and then wound to obtain a bare cell; the bare cell with a capacity of 4.3Ah is placed in an outer packaging foil, and the above-prepared 8.6g electrolyte is injected into the dried battery. After vacuum packaging, standing, forming, shaping and other processes, the secondary battery of Example 1 is obtained.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and hafnium are mixed in a mass ratio of 1:0.015:0.0154 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and niobium are mixed in a mass ratio of 1:0.015:0.0080 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and tungsten are mixed in a mass ratio of 1:0.015:0.0158 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and aluminum are mixed in a mass ratio of 1:0.015:0.0023 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, hafnium boride (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS: 12007-23-7), and titanium are mixed in a mass ratio of 1:0.015:0.0014 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, in step S2), the base material, cobalt boride and titanium dioxide are mixed in an air atmosphere at a mass ratio of 1:0.015:0.007, the sintering temperature is 650°C, and the sintering atmosphere is oxygen.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, in step S2), the base material, cobalt boride and hafnium dioxide are mixed in an air atmosphere at a mass ratio of 1:0.015:0.018, the sintering temperature is 650°C, and the sintering atmosphere is oxygen.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, in step S2), the base material, cobalt boride and niobium pentoxide are mixed in an air atmosphere at a mass ratio of 1:0.015:0.023, the sintering temperature is 650°C, and the sintering atmosphere is oxygen.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, in step S2), the base material, cobalt boride and tungsten trioxide are mixed in an air atmosphere at a mass ratio of 1:0.015:0.020, the sintering temperature is 650°C, and the sintering atmosphere is oxygen.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, in step S2), the base material, cobalt boride and aluminum oxide are mixed in an air atmosphere at a mass ratio of 1:0.015:0.009, the sintering temperature is 650°C, and the sintering atmosphere is oxygen.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, in step S2), the base material, hafnium boride and titanium dioxide are mixed in an air atmosphere at a mass ratio of 1:0.015:0.002, the sintering temperature is 650°C, and the sintering atmosphere is oxygen.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and titanium are mixed in a mass ratio of 1:0.0005:0.0001 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and titanium are mixed in a mass ratio of 1:0.002:0.0005 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and titanium are mixed in a mass ratio of 1:0.004:0.0011 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and titanium are mixed in a mass ratio of 1:0.01:0.0027 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and titanium are mixed in a mass ratio of 1:0.017:0.0047 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and titanium are mixed in a mass ratio of 1:0.02:0.0055 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and hafnium are mixed in a mass ratio of 1:0.02:0.0036 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and hafnium are mixed in a mass ratio of 1:0.02:0.0136 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and hafnium are mixed in a mass ratio of 1:0.015:0.0384 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and hafnium are mixed in a mass ratio of 1:0.015:0.1152 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the base material, cobalt boride and hafnium are mixed in a mass ratio of 1:0.015:0.0351 in step S2).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, in step S2), the base material, hafnium boride and titanium dioxide are mixed in an air atmosphere at a mass ratio of 1:0.015:0.0004, the sintering temperature is 650°C, and the sintering atmosphere is oxygen.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, in step S2), the base material, hafnium boride and titanium dioxide are mixed in an air atmosphere at a mass ratio of 1:0.015:0.0018, the sintering temperature is 650°C, and the sintering atmosphere is oxygen.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, in step S2), the base material, hafnium boride and titanium dioxide are mixed in an air atmosphere at a mass ratio of 1:0.015:0.0120, the sintering temperature is 650° C., and the sintering atmosphere is oxygen.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, in step S2), the base material, hafnium boride and titanium dioxide are mixed in an air atmosphere at a mass ratio of 1:0.015:0.0359, the sintering temperature is 650°C, and the sintering atmosphere is oxygen.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the intermediate material is washed with water at a mass ratio of 1:1 in step S3).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the intermediate material is washed with water at a mass ratio of 1:3 in step S3).
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the vibration frequency of the vibration drying in step S3) is 10 Hz.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the vibration frequency of the vibration drying in step S3) is 15 Hz.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the vibration frequency of the vibration drying in step S3) is 20 Hz.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the vibration frequency of the vibration drying in step S3) is 50 Hz.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, the matrix material is LiNi 0.92 Co 0.07 Mn 0.0087 Sr 0.0013 O 2 , wherein the Li/Me (Me is the sum of all metal elements except lithium) molar ratio is 1.03, the doping amount of strontium is 1500 ppm, and the preparation method is similar to that of Example 1.
  • the preparation of the secondary battery is the same as that of Example 1, except that: in the preparation of the positive electrode active material, the matrix material is LiNi 0.83 Co 0.06 Mn 0.1086 Y 0.0014 O 2 , wherein the Li/Me (Me is the sum of all metal elements except lithium) molar ratio is 1.03, the doping amount of yttrium is 1500 ppm, and the preparation method is similar to that of Example 1.
  • First positive electrode active material The positive electrode active material prepared in Example 1 was used as the first positive electrode material.
  • the second positive electrode active material LiNi 0.92 Co 0.07 Mn 0.009 Sr 0.001 O 2 lithium hydroxide, dried high-nickel ternary precursor Ni 0.92 Co 0.07 Mn 0.01 (OH) 2 and yttrium oxide are weighed according to the stoichiometric ratio of the chemical formula, wherein the molar ratio of Li/Me (Me is the sum of all metal elements except lithium) is 1.03, and the doping amount of strontium is 1500ppm.
  • the mixture is mixed evenly in a high-speed mixer, and then sintered in a kiln at a sintering temperature of 760°C and a sintering time of 20 hours.
  • the sintering atmosphere is oxygen. After cooling, the mixture is crushed by air flow mill, cyclone separation of fine powder, and sieve vibration to obtain a second positive electrode active material with a Dv50 of 3.0 ⁇ m.
  • the first positive electrode active material and the second positive electrode active material are uniformly mixed at a mass ratio of 1:1, and the obtained mixture is used as a positive electrode active material for preparing a positive electrode sheet.
  • the preparation process of the secondary battery is the same as that of Example 1.
  • the preparation of the secondary battery is the same as that of Example 37, except that the first positive electrode active material and the second positive electrode active material are mixed in a mass ratio of 2:1.
  • the preparation of the secondary battery is the same as that of Example 37, except that the first positive electrode active material and the second positive electrode active material are mixed in a mass ratio of 3:1.
  • the preparation of the secondary battery is the same as that of Example 37, except that the first positive electrode active material and the second positive electrode active material are mixed in a mass ratio of 4:1.
  • the preparation of the secondary battery is the same as that of Example 37, except that the first positive electrode active material and the second positive electrode active material are mixed in a mass ratio of 8.5:1.5.
  • the preparation of the secondary battery is the same as that of Example 1, except that the base material LiNi 0.92 Co 0.07 Mn 0.0086 Y 0.0014 O 2 in Example 1 is directly used as the positive electrode active material in the secondary battery.
  • the preparation of the secondary battery is the same as that of Example 1, except that in the preparation of the positive electrode active material, step S3) is not performed, that is, water washing and vibration drying are not performed.
  • the particle size of the positive electrode active material is determined according to GB/T 19077.1-2016/ISO 13320:2009 (laser diffraction method for particle size distribution). Take a clean beaker, add an appropriate amount of the above-mentioned positive electrode active material, add an appropriate amount of pure water, and use ultrasound at 120W/5min to ensure that the material powder is completely dispersed in the water. After the solution is poured into the injection tower of the laser particle size analyzer (Malvern Company, model: Mastersizer3000), it circulates to the test optical path system with the solution. The particles are irradiated by the laser beam, and the particle size distribution characteristics of the particles (shading degree: 8-12%) can be obtained by receiving and measuring the energy distribution of the scattered light. The corresponding values of Dv10, Dv50, and Dv90 are read, and (Dv90-Dv10)/Dv50 is calculated.
  • M is the mass of the small disc with a diameter of 40 mm cut from the positive electrode sheet, which is averaged by 10 weighings
  • d is the thickness of the positive electrode sheet, which is averaged by 10 thickness measurements
  • A is the area of the small disc with a diameter of 40 mm.
  • L1 is the distance between the marks before cold pressing, which is 1000mm
  • L2 is the distance between the marks after cold pressing.
  • the marks are formed in the following way: in the central area of the pole piece, three 1000mm long line segments extending in the length direction of the pole piece are taken at different positions in the width direction of the pole piece, and the two end points of the line segments are marked.
  • L2 is recorded as the average value of the measured value of the distance between the two end points of each line segment after cold pressing.
  • SEM scanning electron microscope
  • the particle size is used to determine whether the particles in the SEM photo belong to the particles of the first positive electrode active material or the particles of the second positive electrode active material.
  • the number of particles of the first positive electrode active material and the number of particles of the second positive electrode active material in each test area are counted through the SEM photos, so as to calculate the average number of particles of the first positive electrode active material and the average number of particles of the second positive electrode active material.
  • the positive electrode active material of the present application achieves a double coating effect on the surface and grain boundaries of the base material through a boron-containing ternary alloy or a boron-containing ternary alloy oxide, which greatly improves the stability of the material surface structure, and the high-temperature storage performance of the secondary battery is significantly improved; 2) compared with the high-nickel positive electrode material of comparative example 2 that has not undergone the water washing and vibration drying process (i.e., only the coating process is carried out, but no subsequent water washing and vibration drying are carried out), the positive electrode active material of the present application has better dispersibility, high filling degree between particles, and while having a high pole piece compaction density, the pole piece elongation is small, which greatly improves the processing performance of the positive pole piece.
  • Examples 36-40 show that when the positive electrode active material of the first aspect of the present application is used as the first positive electrode active material in combination with a second positive electrode active material having a smaller particle size (Dv50 is 3 ⁇ m), the second positive electrode active material with a smaller particle size can effectively fill the pores of the first positive electrode active material with a larger particle size, thereby further improving the processing performance of the electrode sheet.
  • Dv50 is 3 ⁇ m

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Abstract

本申请提供了一种正极活性材料，所述正极活性材料包括基体材料和位于所述基体材料表面的包覆层，其中，所述基体材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a，所述包覆层为含硼三元合金或者含硼三元合金氧化物。本申请的正极活性材料具有高的压实密度，改善的高温存储性能和安全性能。本申请还提供了该正极活性材料的制备方法，以及包含该正极活性材料的正极极片、二次电池、电池模块、电池包和用电装置。

Description

正极活性材料及其制备方法、正极极片、二次电池、电池模块、电池包和用电装置 技术领域
本申请涉及锂电池技术领域，尤其涉及一种正极活性材料及其制备方法，及包括该正极活性材料的正极极片、二次电池、电池模块、电池包和用电装置。
背景技术
近年来，随着锂离子电池的应用范围越来越广泛，锂离子电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。由于锂离子电池取得了极大的发展，因此对其能量密度、循环性能和安全性能等也提出了更高的要求。
正极材料是锂离子电池的重要组成部分，目前常见的正极材料有层状结构材料(例如钴酸锂、锰酸锂、镍酸锂等)、尖晶石结构材料、聚阴离子型材料以及高镍正极材料等。高镍正极材料因其具有较高的能量密度，较低廉的成本以及较可靠的安全性，受到了越来越多的关注。高镍正极材料虽然在能量密度上相比其他材料有了明显提升，但是随着镍含量的增加，材料的热分解温度降低，导致其在循环稳定性和热稳定性方面变差，故电芯的使用寿命较短且存在安全风险，这在一定程度上阻碍了高镍正极材料的进一步发展。因此，需要采取一定策略来优化高镍正极材料，从而在提高电池的能量密度的同时，改善电池的高温存储性能和安全性能。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种正极活性材料，该正极活性材料具有高的压实密度，改善的高温存储性能和安全性能，并提供该正极活性材料的制备方法，以及包含该正极活性材料的 正极极片、二次电池、电池模块、电池包和用电装置。
为了达到上述目的，本申请的第一方面提供了一种正极活性材料，所述正极活性材料包括基体材料和位于所述基体材料表面的包覆层，其中，
所述基体材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a，
所述包覆层为含硼三元合金或者含硼三元合金氧化物。
由此，相对于现有技术，本申请至少包括如下所述的有益效果：1)本申请的正极活性材料分散性好，颗粒间填充度高，具有良好的材料加工性能，具有高的压实密度，能够有效提高电池的能量密度；2)本申请的正极活性材料具有改善的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在任意实施方式中，所述含硼三元合金如式I所示B-X1-X2(I)，其中，X1和X2彼此独立地选自以下的一种元素：钴、铪、铌、钛、锆、钨、铝、钼、铜，所述含硼三元合金氧化物如式II所示B-Y1-Y2-O(II)，其中，Y1和Y2彼此独立地选自以下的一种元素：钴、铪、铌、钛、锆、钨、铝、钼、铜。当包覆层为上述式I所示的含硼三元合金或者式II所示含硼三元合金氧化物时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在任意实施方式中，所述正极活性材料满足：1.30≤(Dv90-Dv10)/Dv50≤2.10。当所述正极活性材料满足上述范围时，正极活性材料分散性好，颗粒间填充度高，具有良好的材料加工性能，具有高的压实密度，从而使电池获得高的能量密度。
在任意实施方式中，所述包覆层的量为500ppm-20000ppm，可选地，所述包覆层的量为4000-15000ppm，基于所述基体材料的重量计。当包覆层的量在上述范围内时，能够有效改善的高镍材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在任意实施方式中，所述含硼三元合金选自以下中的至少一种：硼-钴-铪、硼-钴-铌、硼-钴-钛、硼-钴-锆、硼-钴-钨、硼-钴-铝、硼-钴-钼、硼-钴-铜、硼-铪-钛，可选地，所述含硼三元合金选自以下中的至 少一种：硼-钴-铪、硼-钴-铌、硼-钴-钛、硼-钴-钨、硼-钴-铝、硼-铪-钛。当选择上述含硼三元合金进行表面和晶界包覆时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在任意实施方式中，所述含硼三元合金氧化物选自以下中的至少一种：硼-钴-铪氧化物、硼-钴-铌氧化物、硼-钴-钛氧化物、硼-钴-锆氧化物、硼-钴-钨氧化物、硼-钴-铝氧化物、硼-钴-钼氧化物、硼-钴-铜氧化物、硼-铪-钛氧化物，可选地，所述含硼三元合金氧化物选自以下中的至少一种：硼-钴-铪氧化物、硼-钴-铌氧化物、硼-钴-钛氧化物、硼-钴-钨氧化物、硼-钴-铝氧化物、硼-铪-钛氧化物。当选择上述含硼三元合金氧化物进行表面和晶界包覆时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在任意实施方式中，所述含硼三元合金中的硼、X1和X2的摩尔比为1:0.5:0.04-1:5:4，可选地为1:0.5:0.15-1:1:0.4。当所述含硼三元合金中的各元素的摩尔比满足上述范围时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在任意实施方式中，所述含硼三元合金氧化物中的硼、Y1和Y2的摩尔比为1:0.5:0.03-1:5:5，可选地为1:0.5:0.15-1:1:0.4。当所述含硼三元合金氧化物中的各元素的摩尔比满足上述范围时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在任意实施方式中，所述正极活性材料的Dv50为6μm-18μm，可选地为9μm-13μm。当所述正极活性材料的Dv50在上述范围内时，能够使得所述正极活性材料的压实密度最优化，从而使电池获得高的能量密度。
在任意实施方式中，所述正极活性材料的5吨(即，5T)压力下的压实密度为3.65-3.75g/cm 3。所述正极活性材料具有高的压实密度高，颗粒间填充度高，不仅有利于提高该正极活性材料的加工性能，而且能够有效提高电池的能量密度。
本申请的第二方面提供本申请第一方面的正极活性材料的制备方法，包括
S1)制备基体材料；
S2)将所述基体材料、含硼化合物与金属单质按照质量比为 1:0.004-0.02:0.0001-0.2混合，或者将所述基体材料、含硼化合物与金属氧化物按照质量比为1:0.004-0.02:0.0002-0.018混合，随后进行烧结，烧结气氛为惰性气氛或氧气气氛，得到中间材料；
S3)将所述中间材料进行水洗，经离心，过滤，随后振动干燥，得到正极活性材料，
其中，所述基体材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a。
由此，通过上述方法制备的正极活性材料，分散性好，颗粒间填充度高，具有良好的材料加工性能，具有高的压实密度，改善的表面结构稳定性，由此制备的二次电池具有改善的高温存储性能和安全性能。
在任意实施方式中，所述含硼化合物选自硼化钴、硼化铪、硼化铌、硼化钛、硼化锆、硼化钨、硼化铝、硼化钼和硼化铜中的一种或多种，和/或所述金属单质选自钴、铪、铌、钛、锆、钨、铝、钼和铜中的一种或多种，和/或所述金属氧化物选自氧化钴、氧化铪、氧化铌、氧化钛、氧化锆、氧化钨、氧化铝、氧化钼和氧化铜中的一种或多种。当所述含硼化合物、金属单质化物和金属氧化物分别选自上述材料时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在任意实施方式中，所述步骤S1)制得的基体材料的(Dv90-Dv10)/Dv50≥1.2，可选地，(Dv90-Dv10)/Dv50≥1.25。当基体材料的分布满足上述范围时，由此能够得到分散性好，颗粒间填充度高，具有良好的材料加工性能的正极活性材料。
在任意实施方式中，在所述步骤S2)中，将所述基体材料、含硼化合物与金属单质在惰性气氛下混合，在惰性气氛下烧结，烧结温度为300-700℃，可选为300-550℃，烧结时间为3-10h，可选为5-10h。由此可以得到包覆有含硼三元合金的正极活性材料，从而提高材料的表面结构稳定性，改善电池的高温存储性能和安全性能。
在任意实施方式中，在所述步骤S2)中，将所述基体材料、含硼化合物与金属氧化物在氧气气氛下烧结，烧结温度为300-700℃，可选为550-650℃，烧结时间为3-10h，可选为3-8h。由此，可以得到包覆有 含硼三元合金氧化物的正极活性材料，从而提高材料的表面结构稳定性，改善电池的高温存储性能和安全性能。
在任意实施方式中，在所述步骤S3)中，所述中间材料与水的质量比为1:1-1:5，所述水洗时间为1-10min，所述振动干燥的振动频率为10-50Hz，干燥时间为2-8h。由此能够得到分散性好，颗粒间填充度高，具有良好的材料加工性能的正极活性材料。
本申请的第三方面提供一种正极极片，所述正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括第一正极活性材料，所述第一正极活性材料为本申请第一方面的正极活性材料或通过本申请第二方面的方法制备的正极活性材料，并且所述第一正极活性材料在所述正极膜层中的含量为10重量％以上，基于所述正极膜层的总重量计。由此，可以改善极片的加工性能。
在任意实施方式中，所述正极膜层还包括第二正极活性材料，并且所述第一正极活性材料与所述第二正极活性材料的数量比为6:4-8:2，可选为6.5:3.5-7.5:2.5，所述第二正极活性材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a，并且所述第二正极活性材料的Dv50为2μm-5μm，可选地为2.5μm-3.5μm。由此，可以进一步改善极片的加工性能。
在任意实施方式中，所述第二正极活性材料的振实密度为≤1.8g/cm 3，可选地为1.2-1.5g/cm 3。由此，可以进一步改善极片的加工性能。
本申请的第四方面提供一种二次电池，其包括本申请第三方面的正极极片。
本申请的第五方面提供一种电池模块，其包括本申请的第四方面的二次电池。
本申请的第六方面提供一种电池包，其包括本申请的第五方面的电池模块。
本申请的第七方面提供一种用电装置，其包括选自本申请的第四方面的二次电池、本申请的第五方面的电池模块或本申请的第六方面的电池 包中的至少一种。
本申请的电池模块、电池包和用电装置包括本申请提供的二次电池，因此至少具有与所述二次电池相同的优势。
附图说明
图1是本申请一实施方式的二次电池的示意图。
图2是图1所示的本申请一实施方式的二次电池的分解图。
图3是本申请一实施方式的电池模块的示意图。
图4是本申请一实施方式的电池包的示意图。
图5是图4所示的本申请一实施方式的电池包的分解图。
图6是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53顶盖组件
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的本申请的正极活性材料及其制备方法、正极极片、二次电池、电池模块、电池包和电学装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b” 表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
尽管近年来关于高镍正极材料的研究取得了重要进展，但仍然存在诸多问题亟待解决：1)高镍正极材料循环时会出现过Ni 2+和Li +混排，Ni 2+占据Li +位使得Li +在材料放电时无法嵌入锂层，从而造成材料容量的损失和倍率性能降低；2)由于Ni 4+具有还原性，容易生成Ni 3+，为了保持电荷平衡，材料中会释放出氧气，导致材料结构被破坏，热稳定性降低，高温存储性能变差；3)由于Li +扩散受动力学因素影响，Li的脱出量增多，使过渡金属离子还原，材料要维持其电中性易在表面形成新相及孔隙，导致高镍正极材料结构不稳定，在过充电条件下加速了结构的不稳定性，因其伴随着向尖晶石型和NiO型岩盐相的部分结构转变，并且有 氧气的产生，使得电池的安全性存在一定隐患。目前通常是通过表面包覆、离子掺杂等手段来改善高镍正极材料的电化学性能。对于高镍正极材料在循环使用时出现的析出氧，不仅会氧化有机电解质并形成气体，而且会导致阳离子还原和/或致密化，进而可能以链式反应的方式启动其他降解过程。针对高镍正极材料表面氧稳定的问题，虽然具有高稳定性和催化惰性的薄包覆是有益的，但由于固体对固体的润湿问题以及在电化学循环过程中保持共形的需要，在合成中往往很难达到100％的覆盖率。
针对上述问题，本申请提供了一种正极活性材料，所述正极活性材料包括基体材料和位于所述基体材料表面的包覆层，其中，
所述基体材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a，
所述包覆层为含硼三元合金或者含硼三元合金氧化物。
虽然机理尚不明确，但本申请人意外地发现：本申请提供的正极活性材料，一方面通过含硼三元合金或含硼三元合金氧化物实现对基体材料表面和晶界的双包覆作用，大大提高材料表面结构的稳定性，进而提升材料的存储稳定性和安全性；另一方面本申请的正极活性材料的分散性好，颗粒间填充度高，具有良好的材料加工性能，具有高的压实密度，能够有效提高电池的能量密度。本申请中，所述基体材料为由一次颗粒组成的二次颗粒，含硼三元合金或含硼三元合金氧化物通过与基体材料进行高质量的润湿构建形成紧密结合和全面覆盖，不仅包覆于二次颗粒表面，还位于一次颗粒的晶界位置，实现了对多晶基体材料表面和晶界位置进行全方位的包覆，可以缓解正极侧的晶间应力腐蚀开裂、微结构降解和副反应以及过渡金属对负极的交叉效应，极大的降低材料的产气，使得正极活性材料结构更加稳定，热稳定性和安全性也得到了明显的提升，进而提高了材料的高温存储性能和安全性能。
在本申请中，除非另有说明，否则对于所述基体材料的化学式，当M为两种以上元素时，上述对于a数值范围的限定不仅是对每种作为M的元素的化学计量数的限定，也是对各个作为M的元素的化学计量数之 和的限定。也即，当M为两种以上元素M1、M2……Mn时，M1、M2……Mn各自的化学计量数a1、a2……an各自均需落入本申请对a限定的数值范围内，且a1、a2……an之和也需落入该数值范围内；对于M'为两种以上元素的情况，本申请中对M'化学计量数的数值范围的限定也具有上述含义。
在本申请中，所述Dv10为样品的体积累计百分数达到10％时对应的粒径，所述Dv50为样品的体积累计百分数达到50％时对应的粒径，所述Dv90为样品的体积累计百分数达到90％时对应的粒径，通过(Dv90-Dv10)/Dv50计算可以得出材料的分散性。
在一些实施方式中，所述含硼三元合金如式I所示B-X1-X2(I)，其中，X1和X2彼此独立地选自以下的一种元素：钴、铪、铌、钛、锆、钨、铝、钼、铜，所述含硼三元合金氧化物如式II所示B-Y1-Y2-O(II)，其中，Y1和Y2彼此独立地选自以下的一种元素：钴、铪、铌、钛、锆、钨、铝、钼、铜。当包覆层为上述式I所示的含硼三元合金或者式II所示含硼三元合金氧化物时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在一些实施方式中，所述正极活性材料满足：1.30≤(Dv90-Dv10)/Dv50≤2.10。当所述正极活性材料满足上述范围时，正极活性材料分散性好，颗粒间填充度高，具有良好的材料加工性能，具有高的压实密度，从而使电池获得高的能量密度。
在一些实施方式中，所述包覆层的量为500ppm-20000ppm，可选地，所述包覆层的量为4000-15000ppm，基于所述基体材料的重量计。例如，所述包覆层的量可以为500ppm、2000ppm、4000ppm、10000ppm、15000ppm、17000ppm或20000ppm。当包覆层的量在上述范围内时，能够起到均匀润湿材料表面和晶界的包覆作用，提高材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。若包覆层的量过少，则无法对材料形成良好包覆，无法有效提高材料表面结构稳定性；若包覆层的量过多，则会形成岛状堆积而造成材料克容量的降低以及电芯DCR的提高。
在一些实施方式中，所述含硼三元合金选自以下中的至少一种：硼-钴-铪、硼-钴-铌、硼-钴-钛、硼-钴-锆、硼-钴-钨、硼-钴-铝、硼-钴 -钼、硼-钴-铜、硼-铪-钛，可选地，所述含硼三元合金选自以下中的至少一种：硼-钴-铪、硼-钴-铌、硼-钴-钛、硼-钴-钨、硼-钴-铝、硼-铪-钛。当选择上述含硼三元合金进行表面和晶界包覆时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在一些实施方式中，所述含硼三元合金氧化物选自以下中的至少一种：硼-钴-铪氧化物、硼-钴-铌氧化物、硼-钴-钛氧化物、硼-钴-锆氧化物、硼-钴-钨氧化物、硼-钴-铝氧化物、硼-钴-钼氧化物、硼-钴-铜氧化物、硼-铪-钛氧化物，可选地，所述含硼三元合金氧化物选自以下中的至少一种：硼-钴-铪氧化物、硼-钴-铌氧化物、硼-钴-钛氧化物、硼-钴-钨氧化物、硼-钴-铝氧化物、硼-铪-钛氧化物。当选择上述含硼三元合金氧化物进行表面和晶界包覆时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在一些实施方式中，所述含硼三元合金中的硼、X1和X2的摩尔比为1:0.5:0.04-1:5:4，可选地为1:0.5:0.15-1:1:0.4。当所述含硼三元合金中的各元素的摩尔比满足上述范围时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在一些实施方式中，所述含硼三元合金氧化物中的硼、Y1和Y2的摩尔比为1:0.5:0.03-1:5:5，可选地为1:0.5:0.15-1:1:0.4。当所述含硼三元合金氧化物中的各元素的摩尔比满足上述范围时，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在一些实施方式中，所述正极活性材料的Dv50为6μm-18μm，可选地为9μm-13μm。当所述正极活性材料的Dv50在上述范围内时，能够使得所述正极活性材料的压实密度最优化，从而使电池获得高的能量密度。
在一些实施方式中，所述正极活性材料的5T压力下的压实密度为3.65-3.75g/cm 3。压实密度越高，单位体积活性材料的重量越大，因此提高压实密度有利于提高电芯的体积能量密度。所述正极活性材料具有高的压实密度高，颗粒间填充度高，不仅有利于进一步提高该正极活性材料的加工性能，而且能够进一步提高电池的能量密度。压实密度可依据GB/T 24533-2009测量。
本申请的第二方面提供本申请第一方面的正极活性材料的制备方法， 包括
S1)制备基体材料；
S2)将所述基体材料、含硼化合物与金属单质按照质量比为1:0.004-0.02:0.0001-0.2混合，或者将所述基体材料、含硼化合物与金属氧化物按照质量比为1:0.004-0.02:0.0002-0.018混合，随后进行烧结，烧结气氛为惰性气氛或氧气气氛，得到中间材料；
S3)将所述中间材料进行水洗，经离心，过滤，随后振动干燥，得到正极活性材料，
其中，所述基体材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a。
在本申请中，所述基体材料为由一次颗粒组成的二次颗粒。由此，通过上述制备方法，通过使含硼化合物与金属单质在煅烧时反应相变形成含硼三元合金，或者使含硼化合物与金属氧化物在煅烧时反应相变形成含硼三元合金氧化物，利用含硼三元合金或含硼三元合金氧化物与基体材料之间的反应润湿性，在界面化学反应的强大驱动下，将含硼三元合金或含硼三元合金氧化物不仅完全包覆在二次颗粒的表面，而且注入到了一次颗粒的晶界位置，即，同步实现了表面和晶界的双包覆作用，大大提高了材料材料表面结构的稳定性，进而提升材料的存储稳定性和安全性。
在一些实施方式中，所述含硼化合物选自硼化钴、硼化铪、硼化铌、硼化钛、硼化锆、硼化钨、硼化铝、硼化钼和硼化铜中的一种或多种，和/或所述金属单质选自钴、铪、铌、钛、锆、钨、铝、钼和铜中的一种或多种，和/或所述金属氧化物选自氧化钴、氧化铪、氧化铌、氧化钛、氧化锆、氧化钨、氧化铝、氧化钼和氧化铜中的一种或多种。选择上述所述的含硼化合物、金属单质化物和金属氧化物，可以改善材料的表面结构稳定性，从而改善电池的高温存储性能和安全性能。
在本申请中，可以使用本领域中已知的制备高镍正极材料的方法例如PCT/CN2021/141873制备本申请的基体材料，即，将锂源、高镍氢氧化物前驱体、掺杂剂混合，然后在氧气气氛下，在650-850℃下烧 结，得到本申请的基体材料。
在一些实施方式中，所述步骤S1)制得的基体材料的(Dv90-Dv10)/Dv50≥1.2，可选地，(Dv90-Dv10)/Dv50≥1.25。当基体材料的分布满足上述范围时，由此能够得到分散性好，颗粒间填充度高，具有良好的材料加工性能的正极活性材料。
在一些实施方式中，在所述步骤S2)中，将所述基体材料、含硼化合物与金属单质在惰性气氛下混合，在惰性气氛下烧结，烧结温度为300-700℃，可选为300-550℃，烧结时间为3-10h，可选为5-10h。由此，可以得到包覆有含硼三元合金的正极活性材料，从而提高材料的表面结构稳定性，改善电池的高温存储性能和安全性能。
在一些实施方式中，在所述步骤S2)中，将所述基体材料、含硼化合物与金属氧化物在氧气气氛下烧结，烧结温度为300-700℃，可选为550-650℃，烧结时间为3-10h，可选为3-8h。由此，可以得到包覆有含硼三元合金氧化物的正极活性材料，从而提高材料的表面结构稳定性，改善电池的高温存储性能和安全性能。
在本申请中，在所述步骤S3)中，所述中间材料与水的质量比为1:1-1:5，所述水洗时间为1-10min，所述振动干燥的振动频率为10-50Hz，干燥时间为2-8h。所述振动干燥可以在例如WZG系列卧式振动干燥机上进行，振动频率为可以为例如10Hz以上、15Hz以上、20Hz以上、30Hz以上或50Hz以上，干燥时间可以为例如2h以上、3h以上、4h以上、5h、6h以上、7h以上或8h以上。通过步骤S3)的振动干燥，可以将二次颗粒上的大块截角剥离下来，拓宽了材料粒径分布，使得正极活性材料的分散性好，颗粒间填充度高，具有良好的材料加工性能，具有高的压实密度，能够有效提高电池的能量密度。
本申请的第三方面提供一种正极极片，所述正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括第一正极活性材料，所述第一正极活性材料为本申请第一方面的正极活性材料或通过本申请第二方面的方法制备的正极活性材料，并且所述第一正极活性材料在所述正极膜层中的含量为10重量％以上，基于所述正极膜层的总重量计。通过使用本申请第一方面或通过本申请第二方面制备方法获得的正极活性材料，因其具有良好的分散性， 颗粒间填充度高，从而可以改善极片的加工性能。
在一些实施方式中，所述正极膜层还包括第二正极活性材料，并且所述第一正极活性材料与所述第二正极活性材料的数量比为6:4-8:2，可选为6.5:3.5-7.5:2.5，所述第二正极活性材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a，并且所述第二正极活性材料的Dv50为2μm-5μm，可选地为2.5μm-3.5μm。当使用两种颗粒尺寸不同的正极活性材料，即作为第一正极活性材料的本申请第一方面或通过本申请第二方面制备方法获得的正极活性材料与第二正极活性材料，制成正极极片时，小颗粒的第二正极活性材料可以有效填补大颗粒的第一正极活性材料的孔隙，从而进一步改善极片的加工性能。
在一些实施方式中，所述第二正极活性材料的振实密度为≤1.8g/cm 3，可选地为1.2-1.5g/cm 3。当所述第二正极活性材料的振实密度在上述范围内时，可以进一步改善极片的加工性能。
在本申请中，当所述正极极片的正极膜层包括第一正极材料和第二正极材料时，所述第一正极材料和第二正极材料在5T下的粉体压实密度为3.71-3.83g/cm 3。
另外，以下适当参照附图对本申请的二次电池、电池模块、电池包和用电装置进行说明。
本申请的一个实施方式中，提供一种二次电池。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。在本申请中，电池群裕度为90-95％。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括本申请第一方面的正极活性材料。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面， 正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，正极活性材料采用本申请第一方面的正极活性材料或通过本申请第二方面的方法获得的正极活性材料。所述正极活性材料在正极膜层中的重量比为80-100重量％，基于正极膜层的总重量计。
在一些实施方式中，正极活性材料采用本申请第一方面的正极活性材料作为第一正极材料，同时另外采用这样的正极活性材料作为第二正极活性材料：第二正极活性材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a，并且所述第二正极活性材料的Dv50为2μm-5μm，可选地为2.5μm-3.5μm。当正极活性材料为第一正极活性材料和第二正极活性材料时，第一正极活性材料和第二正极活性材料的质量比为8.5:1.5-5:5。所述正极活性材料在正极膜层中的重量比为80-100重量％，基于正极膜层的总重量计。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。所述粘结剂在正极膜层中的重量比为0-20重量％，基于正极膜层的总重量计。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例， 所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。所述导电剂在正极膜层中的重量比为0-20重量％，基于正极膜层的总重量计。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；其中所述正极浆料固含量为40-80重量％，室温下的粘度调整到5000-25000mPa·s，将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片,正极粉末涂布单位面密度为150-350mg/m 2，正极极片压实密度为3.0-3.6g/cm 3，可选为3.3-3.5g/cm 3。所述压实密度的计算公式为：
压实密度＝涂布面密度/(挤压后极片厚度-集流体厚度)。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料， 还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。所述负极极活性材料可以具有1μm-15μm、优选4μm-9μm的平均粒径(D 10)，具有12μm-22μm、优选14μm-17μm的平均粒径(D 50)，并且具有26μm至40μm、优选30μm-37μm的平均粒径(D 90)。D 10为样品的体积累计分布百分数达到10％时对应的粒径；D 50为样品的体积累计分布百分数达到50％时对应的粒径；D 90为样品的体积累计分布百分数达到90％时对应的粒径。所述负极活性材料在负极膜层中的重量比为70-100重量％，基于负极膜层的总重量计。
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。所述粘结剂在负极膜层中的重量比为0-30重量％，基于负极膜层的总重量计。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。所述导电剂在负极膜层中的重量比为0-20重量％，基于负极膜层的总重量计。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。所述其他助剂在负极膜层中的重量比为0-15重量％，基于负极膜层的总重量计。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料，其中所述负极浆料固含量为30-70重量％，室温下的粘度调整到2000-10000mPa·s；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。负极粉末涂布单位面密度为75-220mg/m 2，负极极片压实密度1.2-2.0g/m 3。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请 对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。所述电解质盐的浓度通常为0.5-5mol/L。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，所述隔离膜的厚度为6-40μm，可选为12-20μm。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图4和图5是作为一个示例的电池包1。参照图4和图5，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图6是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
一、二次电池的制备
实施例1
1.正极活性材料的制备
S1)基体材料LiNi 0.92Co 0.07Mn 0.0086Y 0.0014O 2的制备：按照化学式的计量比称取氢氧化锂、经干燥的高镍三元前驱体Ni 0.92Co 0.07Mn 0.01(OH) 2((Dv90-Dv10)/Dv50为1.45)、氧化钇，其中Li/Me(Me为除锂外的所有金属元素的总和)摩尔比为1.03，钇的掺杂量为1500ppm，将混合物 在高混机中混合均匀后，在窑炉中进行烧结，烧结温度为760℃，烧结时间为20h，烧结气氛为氧气，冷却后，即可得到基体材料。
S2)将上述基体材料、硼化钴(购自于上海阿拉丁生化科技股份有限公司，CAS：12006-77-8)、钛按照质量比为1:0.015:0.0041在高混机中在氮气气氛下进行混合，再将混合物放入窑炉中烧结，烧结温度为350℃，烧结时间为5h，烧结气氛为氮气，得到中间材料。
S3)将该中间材料与水按照质量比为1:5进行水洗，水洗时间为30min，经离心，过滤，随后进行振动干燥，振动频率为30Hz，干燥时间为5h，得到正极活性材料。
2.二次电池的制备
【正极极片】将上述正极活性材料、导电剂乙炔黑、粘接剂聚偏氟乙烯(PVDF)按96:2:2的重量比在适量的N-甲基吡咯烷酮(NMP)中充分搅拌混合，使其形成均匀的正极浆料，浆料的固含量为70重量％。将该正极浆料涂覆于厚度为12μm的铝箔表面上，经干燥、冷压后，得到正极极片，该极片的正极活性材料负载量为21.5mg/cm 2。
【负极极片】将负极活性物质人造石墨、硬碳、导电剂乙炔黑、粘结剂丁苯橡胶(SBR)、增粘剂锂基蒙脱石、增稠剂羧甲基纤维素钠(CMC-Na)按照重量比90:5:2:2:1在去离子水中混合均匀后，涂覆于铜箔上烘干、冷压，得到负极极片。涂覆量为0.015g/cm 2，压实密度为1.65g/cm 3。
【电解液】将碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)体积比1:1:1混合，然后将LiPF 6均匀溶解在上述溶液中得到电解液，其中LiPF 6的浓度为1mol/L。
【隔离膜】隔离膜采购自Cellgard企业，型号为cellgard 2400。
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极极片之间起到隔离的作用，然后卷绕得到裸电芯；将容量为4.3Ah的裸 电芯置于外包装箔中，将上述制备好的8.6g电解液注入到干燥后的电池中，经过真空封装、静置、化成、整形等工序后，得到实施例1的二次电池。所述外包装选择长×宽×高＝148mm×28.5mm×97.5mm的硬壳壳体，壳体材料为铝，壳体厚度为0.8mm，电池的群裕度为94％。
实施例2
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、铪按照质量比为1:0.015:0.0154混合。
实施例3
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、铌按照质量比为1:0.015:0.0080混合。
实施例4
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、钨按照质量比为1:0.015:0.0158混合。
实施例5
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、铝按照质量比为1:0.015:0.0023混合。
实施例6
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化铪(购自于购自于上海阿拉丁生化科技股份有限公司，CAS：12007-23-7)、钛按照质量比为1:0.015:0.0014混合。
实施例7
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、二氧化钛按照质量比为1:0.015:0.007在空气气氛下混合，烧结温度为650℃，烧结气氛为氧气。
实施例8
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、二氧化铪按照质量比为1:0.015:0.018在空气气氛下混合，烧结温度为650℃，烧结气氛为氧气。
实施例9
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、五氧化二铌按照质量比为1:0.015:0.023在空气气氛下混合，烧结温度为650℃，烧结气氛为氧气。
实施例10
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、三氧化钨按照质量比为1:0.015:0.020在空气气氛下混合，烧结温度为650℃，烧结气氛为氧气。
实施例11
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、三氧化二铝按照质量比为1:0.015:0.009在空气气氛下混合，烧结温度为650℃，烧结气氛为氧气。
实施例12
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化铪、二氧化钛按照质量比为1:0.015:0.002在空气气氛下混合，烧结温度为650℃，烧结气氛为氧气。
实施例13
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、钛按照质量比为1:0.0005:0.0001混合。
实施例14
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、钛按照质量比为1:0.002:0.0005混合。
实施例15
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、钛按照质量比为1:0.004:0.0011混合。
实施例16
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、钛按照质量比为1:0.01:0.0027混合。
实施例17
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、钛按照质量比为1:0.017:0.0047混合。
实施例18
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、钛按照质量比为1:0.02:0.0055混合。
实施例19
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备 中，在步骤S2)中将基体材料、硼化钴、铪按照质量比为1:0.02:0.0036混合。
实施例20
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、铪按照质量比为1:0.02:0.0136混合。
实施例21
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、铪按照质量比为1:0.015:0.0384混合。
实施例22
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、铪按照质量比为1:0.015:0.1152混合。
实施例23
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化钴、铪按照质量比为1:0.015:0.0351混合。
实施例24
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化铪、二氧化钛按照质量比为1:0.015:0.0004在空气气氛下混合，烧结温度为650℃，烧结气氛为氧气。
实施例25
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化铪、二氧化钛按照质量比为 1:0.015:0.0018在空气气氛下混合，烧结温度为650℃，烧结气氛为氧气。
实施例26
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化铪、二氧化钛按照质量比为1:0.015:0.0120空气气氛下混合，烧结温度为650℃，烧结气氛为氧气。
实施例27
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S2)中将基体材料、硼化铪、二氧化钛按照质量比为1:0.015:0.0359在空气气氛下混合，烧结温度为650℃，烧结气氛为氧气。
实施例28
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S3)中将中间材料与水按照质量比为1:1进行水洗。
实施例29
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S3)中将中间材料与水按照质量比为1:3进行水洗。
实施例30
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S3)中进行振动干燥的振动频率为10Hz。
实施例31
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S3)中进行振动干燥的振动频率为15Hz。
实施例32
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S3)中进行振动干燥的振动频率为20Hz。
实施例33
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，在步骤S3)中进行振动干燥的振动频率为50Hz。
实施例34
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，基体材料为LiNi 0.92Co 0.07Mn 0.0087Sr 0.0013O 2，其中Li/Me(Me为除锂外的所有金属元素的总和)摩尔比为1.03，锶的掺杂量为1500ppm，其制备方法类似于实施例1。
实施例35
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，基体材料为LiNi 0.83Co 0.06Mn 0.1086Y 0.0014O 2，其中Li/Me(Me为除锂外的所有金属元素的总和)摩尔比为1.03，钇的掺杂量为1500ppm，其制备方法类似于实施例1。
实施例36
第一正极活性材料：使用实施例1中制得的正极活性材料作为第一正极材料。
第二正极活性材料LiNi 0.92Co 0.07Mn 0.009Sr 0.001O 2的制备：按照化学式的计量比称取氢氧化锂、经干燥的高镍三元前驱体Ni 0.92Co 0.07Mn 0.01(OH) 2、氧化钇，其中Li/Me(Me为除锂外的所有金属元素的总和)摩尔比为1.03，锶的掺杂量为1500ppm，将混合物在高混机中混合均匀后，在窑炉中进行烧结，烧结温度为760℃，烧结时间为20h，烧结气氛为氧气，冷却后，经由气流磨破碎，旋风分离微粉，振筛，得到Dv50为3.0μm的第二正极活性材料。
将第一正极活性材料与第二正极活性材料以质量比为1:1混合均匀，得到的混合物作为用于制备正极极片的正极活性材料。
二次电池的制备过程与实施例1相同。
实施例37
二次电池的制备与实施例37相同，区别在于：将第一正极活性材料与第二正极活性材料以质量比为2:1混合。
实施例38
二次电池的制备与实施例37相同，区别在于：将第一正极活性材料与第二正极活性材料以质量比为3:1混合。
实施例39
二次电池的制备与实施例37相同，区别在于：将第一正极活性材料与第二正极活性材料以质量比为4:1混合。
实施例40
二次电池的制备与实施例37相同，区别在于：将第一正极活性材料与第二正极活性材料以质量比为8.5:1.5混合。
对比例1
二次电池的制备与实施例1相同，区别在于：直接使用实施例1中的基体材料LiNi 0.92Co 0.07Mn 0.0086Y 0.0014O 2作为二次电池中的正极活性材料。
对比例2
二次电池的制备与实施例1相同，区别在于：在正极活性材料的制备中，没有进行S3)步骤，即没有进行水洗和振动干燥。
二、相关参数的测试
(1)压实密度测试
取一定量的粉末放于压实专用模具中,然后将模具放在压实密度仪器上。施加5T的压力，在设备上读出压力下粉末的厚度(卸压后的厚度)，通过ρ＝m/v，计算出压实密度。
结果参见表1。
(2)粒径测试
根据GB/T 19077.1-2016/ISO 13320:2009(粒度分布激光衍射法)测定正极活性材料的粒径。取一洁净烧杯，加入适量的上述正极活性材料，加入适量纯水，超声120W/5min确保材料粉末在水中完全分散。溶液倒入激光粒度分析仪(马尔文公司，型号：Mastersizer3000)的进样塔后随溶液循环到测试光路系统，颗粒在激光束的照射下，通过接受和测量散向光的能量分布可得到颗粒的粒度分布特征(遮光度：8-12％)，读取Dv10、Dv50、Dv90的相应数值，从而计算出(Dv90-Dv10)/Dv50。
结果参见表1和表2。
(3)正极极片的压实密度
正极极片的压实密度PD是通过公式PD＝M/(d×A)计算得到的。式中，M为在正极极片上切割出的直径40mm小圆片的质量，通过10次称重取平均值；d为正极极片厚度，通过10次测量厚度取平均值；A为该直径40mm小圆片的面积。
测试结果参见表1和表2。
(4)正极极片的延展率
正极极片冷压后的长度方向延展率通过公式ΔEL％＝(L2-L1)/L1×100％计算得到。式中，L1为冷压前标记之间的距离，为1000mm，L2为冷压后标记之间的距离。所述标记通过如下方式形成：在极片的中心区域，在极片宽度方向上的不同位置分别取三段在极片长度方向上延伸的1000mm长的线段，并标记线段的两个端点。L2记为冷压后各线段两端点之间距离的实测值的平均值。
测试结果参见表1和表2。
(5)正极极片中正极活性材料的粒径和数量
在正极极片的横截断面上随机选取10个区域，使用扫描电子显微镜ZEISS Sigma 300，参考JY/T010-1996，获取各区域的扫描电子显微镜照片。在扫描电子显微镜(SEM)照片中，测量颗粒的粒径。通过颗粒粒 径判断SEM照片中的颗粒属于第一正极活性材料的颗粒还是第二正极活性材料的颗粒。通过SEM照片分别统计各测试区域中第一正极活性材料的颗粒的数量和第二正极活性材料的颗粒的数量，从而分别计算出第一正极活性材料颗粒数量的平均值以及第二正极活性材料颗粒数量的平均值。
三、二次电池性能的测试
60℃存储容量保持率：
在25℃的恒温环境下，静置5min，按照1/3C放电至2.8V，静置5min，按照1/3C充电至4.25V，然后在4.25V下恒压充电至电流≤0.05mA，静置5min，此时的充电容量记为C0，然后按照1/3C放电至2.8V，此时的放电容量为初始克容量，记为D0。然后将电池由0.33C恒流充电至4.25V并恒压至电流≤0.05mA，静置5min，然后放入60℃的高低温箱中，静置1h待电池温度达到目标温度后进行存储。15天后取出，在25℃的恒温环境下，重复前面过程，并每隔15天记录一次容量Dn(n＝0,1,2……)，计算60天存储后容量保持率：(D4-D0)/D0*100％。
Figure PCTCN2022121607-appb-000001
Figure PCTCN2022121607-appb-000002
由以上内容可以看出，1)与对比例1的没有经包覆的高镍正极材料(即，现有技术中的高镍正极材料)相比，本申请的正极活性材料，通过含硼三元合金或含硼三元合金氧化物实现对基体材料表面和晶界的双包覆作用，大大提高了材料表面结构的稳定性，二次电池的高温存储性能得到明显改善；2)与对比例2的没有经过水洗和振动干燥过程的高镍正极材料(即，仅进行了包覆过程，但没有进行后续的水洗和振动干燥)相比，本申请的正极活性材料分散性更好，颗粒间填充度高，在具有高的极片压实密度的同时，极片延展率较小，大大改善了正极极片的加工性能。此外，实施例36-40的结果表明，当将本申请第一方面的正极活性材料作为第一正极活性材料与具有较小粒径的第二正极活性材料(Dv50为3μm)组合一起使用时，较小粒径的第二正极活性材料可以有效填补粒径较大的第一正极活性材料的孔隙，从而进一步改善极片的加工性能。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (23)

  1. 一种正极活性材料，其特征在于，所述正极活性材料包括基体材料和位于所述基体材料表面的包覆层，其中，
    所述基体材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a，
    所述包覆层为含硼三元合金或者含硼三元合金氧化物。
  2. 根据权利要求1所述的正极活性材料，其特征在于，所述含硼三元合金如式I所示B-X1-X2(I)，
    其中，X1和X2彼此独立地选自以下的一种元素：钴、铪、铌、钛、锆、钨、铝、钼、铜，
    所述含硼三元合金氧化物如式II所示B-Y1-Y2-O(II)，
    其中，Y1和Y2彼此独立地选自以下的一种元素：钴、铪、铌、钛、锆、钨、铝、钼、铜。
  3. 根据权利要求1所述的正极活性材料，其特征在于，所述正极活性材料满足：1.30≤(Dv90-Dv10)/Dv50≤2.10。
  4. 根据权利要求1或2所述的正极活性材料，其特征在于，所述包覆层的量为500ppm-20000ppm，可选地，所述包覆层的量为4000-15000ppm，基于所述基体材料的重量计。
  5. 根据权利要求1或2所述的正极活性材料，其特征在于，所述含硼三元合金选自以下中的至少一种：硼-钴-铪、硼-钴-铌、硼-钴-钛、硼-钴-锆、硼-钴-钨、硼-钴-铝、硼-钴-钼、硼-钴-铜、硼-铪-钛，可选地，所述含硼三元合金选自以下中的至少一种：硼-钴-铪、硼-钴-铌、硼-钴-钛、硼-钴-钨、硼-钴-铝、硼-铪-钛。
  6. 根据权利要求1或2所述的正极活性材料，其特征在于，所述含硼三元合金氧化物选自以下中的至少一种：硼-钴-铪氧化物、硼-钴-铌氧化物、硼-钴-钛氧化物、硼-钴-锆氧化物、硼-钴-钨氧化物、硼-钴-铝氧化物、硼-钴-钼氧化物、硼-钴-铜氧化物、硼-铪-钛氧化物，可选地，所述含硼三元合金氧化物选自以下中的至少一种：硼-钴-铪氧化物、硼-钴-铌氧化物、硼-钴-钛氧化物、硼-钴-钨氧化物、硼-钴-铝氧化物、硼-铪-钛氧 化物。
  7. 根据权利要求1或2所述的正极活性材料，其特征在于，所述含硼三元合金中的硼、X1和X2的摩尔比为1:0.5:0.04-1:5:4，可选地为1:0.5:0.15-1:1:0.4。
  8. 根据权利要求1或2所述的正极活性材料，其特征在于，所述含硼三元合金氧化物中的硼、Y1和Y2的摩尔比为1:0.5:0.03-1:5:5，可选地为1:0.5:0.15-1:1:0.4。
  9. 根据权利要求1或2所述的正极活性材料，其特征在于，所述正极活性材料的Dv50为6μm-18μm，可选地为9μm-13μm。
  10. 根据权利要求1或2所述的正极活性材料，其特征在于，所述正极活性材料的5T压力下的压实密度为3.65-3.75g/cm 3。
  11. 一种权利要求1-10中任一项的正极活性材料的制备方法，其特征在于，包括
    S1)制备基体材料；
    S2)将所述基体材料、含硼化合物与金属单质按照质量比为1:0.004-0.02:0.0001-0.2混合，或者将所述基体材料、含硼化合物与金属氧化物按照质量比为1:0.004-0.02:0.0002-0.018混合，随后进行烧结，烧结气氛为惰性气氛或氧气气氛，得到中间材料；
    S3)将所述中间材料进行水洗，经离心，过滤，随后振动干燥，得到正极活性材料，
    其中，所述基体材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a。
  12. 根据权利要求11的所述制备方法，其特征在于，所述含硼化合物选自硼化钴、硼化铪、硼化铌、硼化钛、硼化锆、硼化钨、硼化铝、硼化钼和硼化铜中的一种或多种，和/或
    所述金属单质选自钴、铪、铌、钛、锆、钨、铝、钼和铜中的一种或多种，和/或
    所述金属氧化物选自氧化钴、氧化铪、氧化铌、氧化钛、氧化锆、氧化钨、氧化铝、氧化钼和氧化铜中的一种或多种。
  13. 根据权利要求11或12的所述制备方法，其特征在于，所述步骤S1)制得的基体材料的(Dv90-Dv10)/Dv50≥1.2，可选地，(Dv90-Dv10)/Dv50≥1.25。
  14. 根据权利要求11或12的所述制备方法，其特征在于，在所述步骤S2)中，将所述基体材料、含硼化合物与金属单质在惰性气氛下混合，在惰性气氛下烧结，烧结温度为300-700℃，可选为300-550℃，烧结时间为3-10h，可选为5-10h。
  15. 根据权利要求11或12的所述制备方法，其特征在于，在所述步骤S2)中，将所述基体材料、含硼化合物与金属氧化物在氧气气氛下烧结，烧结温度为300-700℃，可选为550-650℃，烧结时间为3-10h，可选为3-8h。
  16. 根据权利要求11或12的所述制备方法，其特征在于，在所述步骤S3)中，所述中间材料与水的质量比为1:1-1:5，所述水洗时间为1-10min，所述振动干燥的振动频率为10-50Hz，干燥时间为2-8h。
  17. 一种正极极片，其特征在于，所述正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括第一正极活性材料，所述第一正极活性材料为权利要求1-10中任一项所述的正极活性材料或通过权利要求11-16中任一项所述的方法制备的正极活性材料，并且所述第一正极活性材料在所述正极膜层中的含量为10重量％以上，基于所述正极膜层的总重量计。
  18. 根据权利要求17所述的正极极片，其特征在于，所述正极膜层还包括第二正极活性材料，并且所述第一正极活性材料与所述第二正极活性材料的数量比为6:4-8:2，可选为6.5:3.5-7.5:2.5，
    所述第二正极活性材料的化学式为LiNi xCo yMn zM aM' bO 2，M＝Zr、Y、Al、Ti、W、Sr、Ta、Sb、Nb、Na、K、Ca或Ce中的至少一种，M'＝N、F、S或Cl中的至少一种，0.80≤x≤1.0，0≤y≤0.20，0≤z≤0.02，0≤a≤0.02，b＝1-x-y-z-a，并且所述第二正极活性材料的Dv50为2μm-5μm，可选地为2.5μm-3.5μm。
  19. 根据权利要求18所述的正极极片，其特征在于，所述第二正极活性材料的振实密度为≤1.8g/cm 3，可选地为1.2-1.5g/cm 3。
  20. 一种二次电池，其特征在于，包括权利要求17-19中任一项所述 的正极极片。
  21. 一种电池模块，其特征在于，包括权利要求20所述的二次电池。
  22. 一种电池包，其特征在于，包括权利要求21所述的电池模块。
  23. 一种用电装置，其特征在于，包括选自权利要求20所述的二次电池、权利要求21所述的电池模块或权利要求22所述的电池包中的至少一种。
PCT/CN2022/121607 2022-09-27 2022-09-27 正极活性材料及其制备方法、正极极片、二次电池、电池模块、电池包和用电装置 WO2024065157A1 (zh)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016033854A (ja) * 2014-07-31 2016-03-10 日亜化学工業株式会社 非水電解液二次電池用正極活物質
CN111527630A (zh) * 2018-02-23 2020-08-11 株式会社Lg化学 二次电池用正极活性材料、其制备方法以及包含其的锂二次电池
CN111943284A (zh) * 2020-08-19 2020-11-17 中南大学 一种富镍三元材料及其制备方法和应用
CN113629254A (zh) * 2021-10-12 2021-11-09 浙江帕瓦新能源股份有限公司 一种单晶类高镍低钴或无钴正极材料的制备方法

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Publication number Priority date Publication date Assignee Title
JP2016033854A (ja) * 2014-07-31 2016-03-10 日亜化学工業株式会社 非水電解液二次電池用正極活物質
CN111527630A (zh) * 2018-02-23 2020-08-11 株式会社Lg化学 二次电池用正极活性材料、其制备方法以及包含其的锂二次电池
CN111943284A (zh) * 2020-08-19 2020-11-17 中南大学 一种富镍三元材料及其制备方法和应用
CN113629254A (zh) * 2021-10-12 2021-11-09 浙江帕瓦新能源股份有限公司 一种单晶类高镍低钴或无钴正极材料的制备方法

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