Positive electrode active material, preparation method therefor, and use thereof

Abstract

A positive electrode active material, a preparation method therefor, and a use thereof, relating to the technical field of lithium-ion batteries. The chemical formula of the positive electrode active material is LixNiaCobMn1-a-bMcO2, where 1≤x≤1.08, 0.6≤a≤0.98, 0<b≤0.20, 0<c≤0.030, and the binding energy of the element M and oxygen is at least twice the binding energy of a lithium-oxygen bond. The positive electrode active material satisfies [Formula 1]. In the formula, Φ is a surface particle distribution rate, the surface particles being primary particles on the surface of secondary particles, γ is a stacking thickness in the direction of the positive electrode active material (104), and D(104) is a grain size in the direction of the positive electrode active material (104). The foregoing provides an improvement in terms of internal stress transfer, thereby solving the problem of secondary particle cracking and prolonging the service life of the positive electrode active material.

Description

Cathode active material and preparation method and use thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a cathode active material and a preparation method and use thereof. BACKGROUND

[0002] Lithium ion batteries have been widely used in consumer electronics, and the rapid development of new energy vehicle industry has put forward higher requirements on the performance of power batteries such as energy density, safety, fast charging and discharging, and cycle life. Lithium nickel manganese cobalt oxide cathode material (referred to as multi-element material) has become the mainstream product of high-performance lithium ion battery cathode material. In order to improve the energy density, the multi-element material develops towards high nickel. Under the same voltage, high-nickel multi-element material can extract more lithium ions. However, during the cycle process, due to the stress concentration and the difficulty of uniform conduction during the lithium ion intercalation-extraction process, the secondary particles of the cathode active material crack due to uneven distribution of internal stress, affecting the cycle performance of the battery.

[0003] The prior art generally alleviates the cracking and breaking phenomenon of secondary particles during the cycle process through doping, coating and other technical means. However, doping and coating are to improve the particle strength of primary particles to achieve the above purpose, and the strength of the primary particles of the ternary cathode active material is ≥300Mpa, and the strength of the primary particles does not need to be excessively improved, and the prior art does not solve the fundamental problem of stress concentration.

[0004] SUMMARY

[0005] The present application provides a cathode active material and a preparation method and use thereof to solve the problem of easy cracking and breaking of secondary particles caused by stress concentration.

[0006] In a first aspect, the present application provides a cathode active material, the chemical formula of the cathode active material is Li x Ni a Co b Mn 1-a-b M c O2, wherein 1≤x≤1.08, 0.6≤a≤0.98, 0<b≤0.20, 0<c≤0.030, the binding energy of M element and oxygen is more than 2 times the lithium-oxygen bond energy;

[0007] The cathode active material satisfies the following relationship:

[0008] In the formula, Φ is the distribution rate of surface particles, and the surface particles are primary particles on the surface of secondary particles;

[0009] ND10 is the particle size corresponding to the cumulative particle size distribution percentage of 10% of surface particles, ND50 is the particle size corresponding to the cumulative particle size distribution percentage of 50% of surface particles, and ND90 is the particle size corresponding to the cumulative particle size distribution percentage of 90% of surface particles;

[0010] γ is the stacking thickness in the direction of the positive electrode active material (104), and D(104) is the grain size in the direction of the positive electrode active material (104).

[0011] In an alternative embodiment, 0.30≤Φ≤1.20.

[0012] In an alternative embodiment, 3≤γ≤15.

[0013] In an alternative embodiment, ND50 is 270-800 nm, and optionally, ND50 is 400-700 nm.

[0014] In an alternative embodiment, ND90 is 300-2000 nm, and optionally, ND90 is 500-1800 nm.

[0015] In an alternative embodiment, ND10 is 50-500 nm, and optionally, ND10 is 100-400 nm.

[0016] In an alternative embodiment, D(104) is 35-150 nm, and optionally, D(104) is 45-120 nm.

[0017] In an alternative embodiment, M is selected from at least one of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, Sm;

[0018] Optionally, M is selected from at least two of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, Sm;

[0019] Optionally, 0.80≤a≤0.98.

[0020] Optionally, 0.005≤c≤0.025.

[0021] In an alternative embodiment, the positive electrode active material satisfies at least one of the following conditions:

[0022] (1) the specific surface area is 0.2-1.2 m 2 / g, and optionally, 0.4-0.8 m 2 / g;

[0023] (2) the surface residual alkali content satisfies Li2CO3≤6000ppm, LiOH≤8000ppm; optionally, Li2CO3≤4000ppm, LiOH≤6000ppm;

[0024] (3) the particle size median D50 of the positive electrode active material is 2.0-25.0um, optionally 3.0-18.0um.

[0025] In a second aspect, the present application provides a preparation method of a positive electrode active material, comprising the following steps:

[0026] S1, mixing a lithium salt, a first additive containing M, and a nickel-cobalt-manganese hydroxide precursor to obtain a mixture;

[0027] S2, performing first sintering on the mixture at 600-800℃ to obtain an active intermediate;

[0028] S3, performing second sintering on the active intermediate at 200-800℃ to obtain a positive electrode active material;

[0029] The binding energy of M and oxygen is more than 2 times of the lithium-oxygen bond energy.

[0030] In an optional embodiment, between S2 and S3, the active intermediate is further mixed with a second additive containing M.

[0031] Optionally, M in the first additive and the second additive is independently selected from at least one of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, Sm.

[0032] Optionally, M in the first additive and the second additive is selected from different elements.

[0033] In an optional embodiment, M in the first additive is selected from at least two of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, Sm.

[0034] In an optional embodiment, the content of Ni in the nickel-cobalt-manganese hydroxide precursor accounts for 0.60-0.98 of the total molar amount of nickel, cobalt and manganese elements.

[0035] In an optional embodiment, the lithium salt is selected from any one of lithium hydroxide monohydrate, lithium nitrate, lithium sulfate, lithium carbonate or anhydrous lithium hydroxide.

[0036] In an optional embodiment, the lithium ratio is 1:(1-1.08); optionally, 1:(1.01-1.06). The lithium ratio is the molar ratio of Li to the total amount of transition metals.

[0037] In an alternative embodiment, the time for the first sintering is 8-26h, alternatively 8-24h.

[0038] In an alternative embodiment, the time for the second sintering is 2-18h, alternatively 5-18h.

[0039] In an alternative embodiment, the first sintering is performed in air or oxygen atmosphere.

[0040] In an alternative embodiment, the atmosphere for the second sintering is selected from any one of air, oxygen or a mixture of the two, alternatively oxygen.

[0041] In an alternative embodiment, the temperature for the first sintering is 700-800℃.

[0042] In an alternative embodiment, the temperature for the second sintering is 250-650℃.

[0043] In a third aspect, the present application provides a positive electrode tab, comprising:

[0044] a positive electrode current collector, and

[0045] a positive electrode film layer disposed on at least one side of the positive electrode current collector, the positive electrode film layer comprising the positive electrode active material or the positive electrode active material prepared according to the method.

[0046] In a fourth aspect, the present application provides a secondary battery comprising the positive electrode tab.

[0047] In a fifth aspect, the present application provides an electric device comprising the secondary battery.

[0048] The technical solution of the present application has the following advantages:

[0049] The present application improves from the aspect of internal stress transmission, and the transmission of stress between the primary particles with the narrow distribution defined in the present application is more uniform, which solves the problem of cracking of the secondary particles caused by poor stress transmission between the primary particles, reduces the probability of side reactions, and improves the service life of the positive electrode active material. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0051] Fig. 1 is a scanning electron microscope image of the positive electrode active material of Example 1;

[0052] Fig. 2 is an XRD pattern of the positive electrode active material of Example 1;

[0053] Fig. 3 is a surface particle normal distribution diagram of Example 1;

[0054] Fig. 4 is a surface particle normal distribution diagram of Example 1, Comparative Example 1 and Comparative Example 2. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion.

[0057] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0058] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0059] The ranges disclosed herein are defined by their lower and upper limits. Ranges that include both endpoints are inclusive of the endpoints, and ranges that exclude both endpoints are not inclusive of the endpoints. Ranges are combinable and include any and all intermediate ranges, and the endpoints of the ranges are independently combinable. For example, the range of "60% to 120%" is combinable with the range of "80% to 110% to form a range of "60% to 110%, "60% to 120%, "80% to 120%, and "80% to 110%. All of these ranges are inclusive of the endpoints. Also, the minimum range values of 1 and 2 are combinable with the maximum range values of 3, 4, and 5 to form the following ranges: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, the use of "and / or" means that the listed items are individually useful and also any combination of those items. For example, "A and / or B" means A alone, B alone, or A and B. In addition, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0060] In the description of the embodiments of the present application, the term "and / or" is merely an association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally means that the front and rear associated objects are in an "or" relationship.

[0061] In the description of the embodiments of the present application, the term "a plurality of" means two or more (including two), and similarly, "a plurality of groups" means two or more groups (including two groups), and "a plurality of pieces" means two or more pieces (including two pieces).

[0062] During the cycle process, the stress concentration problem in the embedding and extraction process of lithium ions causes the positive electrode active material secondary particles to crack due to uneven internal stress distribution, affecting the cycle performance of the battery.

[0063] In order to solve the problems in the related art described above, according to a first aspect of the present application, a positive electrode active material is provided, the chemical formula of the positive electrode active material is Li x Ni a Co b Mn 1-a-b M c O2, wherein 1≤x≤1.08, 0.6≤a≤0.98, 0<b≤0.20, 0<c≤0.030, the binding energy of the element M and oxygen is more than 2 times the lithium-oxygen bond energy;

[0064] The positive electrode active material satisfies the following relationship: In the formula, Φ is the distribution rate of surface particles, the surface particles are primary particles on the surface of secondary particles; ND10 is the particle size corresponding to the cumulative particle size distribution percentage of surface particles reaching 10%; ND50 is the particle size corresponding to the cumulative particle size distribution percentage of surface particles reaching 50%; ND90 is the particle size corresponding to the cumulative particle size distribution percentage of surface particles reaching 90%; γ is the stacking thickness of the positive electrode active material (104) direction; and D(104) is the grain size of the positive electrode active material (104) direction. For example, a can be selected from 0.6, 0.7, 0.8, 0.9, and 0.98.

[0065] The binding energy of the M element and oxygen is obtained from the NIST X-ray Photoelectron Spectroscopy Database. For example, the binding energy of each element and oxygen is shown in Table 1.

[0066] Table 1 Binding energy of each element and oxygen

[0067] The stacking thickness γ of the positive electrode active material (104) direction represents the ratio of the particle ND50 size to the (104) direction grain size D(104), which quantifies the degree of particle preferred orientation, wherein D(104) can be calculated by the Scherrer formula.

[0068] In the formula, θ is the Bragg diffraction angle, K is the Scherrer formula constant, K = 0.89, λ is the X-ray wavelength 0.154056 nm; and B is the half-height width of the diffraction peak.

[0069] The present application improves the stress transmission from the aspect of internal stress transmission, and the stress transmission mode between the primary particles with narrow distribution defined in the present application is more uniform, the problem of secondary particle cracking caused by poor stress transmission between primary particles is solved, the probability of side reaction is reduced, and the service life of the positive electrode active material is improved. Under the fluxing effect of the oxygenophilic element, strong binding of oxygen formed on the crystal surface can be formed, the scanning electron microscope morphology of the primary particles is more uniform, and the narrow distribution of the primary particles can make the stress transmission mode between the particles more uniform. Moreover, the present application solves the problem of stress concentration to avoid secondary particle cracking and breaking, rather than continuously improving the strength of the primary particles, which can avoid affecting the compressibility of the positive electrode material due to the excessively high strength, reduce the compaction density of the positive electrode, and reduce the energy density.

[0070] In an alternative embodiment, 0.30≤Φ≤1.20. The cycle life of the positive electrode active material performs better within this range. Exemplarily, Φ can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 or 1.2.

[0071] In an alternative embodiment, 3≤γ≤15. The cycle life of the positive electrode active material performs better within this range. Exemplarily, γ can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15.

[0072] In an alternative embodiment, ND50 is 270-800 nm, optionally, ND50 is 400-700 nm. Exemplarily, ND50 can be 270 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 or 800 nm.

[0073] In an alternative embodiment, ND90 is 300-2000 nm, optionally, ND90 is 500-1800 nm. Exemplarily, ND90 can be 300 nm, 400 nm, 500 nm, 600 nm, 800 nm, 1000 nm, 1200 nm, 1600 nm, 1800 nm or 2000 nm.

[0074] In an alternative embodiment, ND10 is 50-500 nm, optionally, ND10 is 100-400 nm. Exemplarily, ND90 can be 50 nm, 100 nm, 200 nm, 300 nm, 400 nm or 500 nm.

[0075] In an alternative embodiment, D(104) is 35-150 nm, optionally, D(104) is 45-120 nm. Exemplarily, D(104) can be 45 nm, 50 nm, 60 nm, 80 nm, 100 nm, 120 nm, 130 nm or 150 nm.

[0076] In an alternative embodiment, the M is selected from at least one of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, Sm.

[0077] Optionally, the M is selected from two or more of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, Sm. The use of two or more elements for doping M can further improve the capacity of the positive electrode active material.

[0078] Optionally, M is selected from 2 or 3 of Bi, Sr, B, Ti, Y, Zr, Nb, W, Ce;

[0079] Optionally, 0.80≤a≤0.98;

[0080] Optionally, 0.005≤c≤0.025;

[0081] Optionally, 0.005≤c≤0.020.

[0082] In an optional embodiment, the positive electrode active material satisfies at least one of the following conditions:

[0083] (1) the specific surface area is 0.2-1.2m 2 / g, and optionally 0.4-0.8m 2 / g;

[0084] (2) the surface residual alkali content satisfies Li2CO3≤6000ppm, LiOH≤8000ppm; and optionally, Li2CO3≤4000ppm, LiOH≤6000ppm;

[0085] (3) the particle size median D50 of the positive electrode active material is 2.0-25.0um, and optionally 3.0-18.0um;

[0086] D50 is optionally 3.0-12.0um.

[0087] In a second aspect, the present application further provides a preparation method of the positive electrode active material, comprising the following steps:

[0088] S1, mixing a lithium salt, a first additive containing M, and a nickel-cobalt-manganese hydroxide precursor to obtain a mixture;

[0089] S2, performing first sintering on the mixture at 600-800℃ to obtain an active intermediate;

[0090] S3, performing second sintering on the active intermediate at 200-800℃ to obtain the positive electrode active material;

[0091] The binding energy of M and oxygen is more than 2 times the binding energy of lithium and oxygen.

[0092] The preparation method of the application adopts high-binding-energy oxygenophilic elements to match a suitable sintering temperature, and under the fluxing action of the oxygenophilic elements, a strong binding is formed on the crystal surface oxygen, the scanning electron microscope morphology of the primary particles is more uniform, the narrow distribution of the primary particles can make the stress transmission between the particles more uniform, solve the problem of secondary particle cracking caused by uneven particle stress transmission, reduce the probability of side reactions, and improve the service life of the positive electrode active material. Through twice sintering, the residual alkali content on the surface of the positive electrode active material can be reduced, and the subsequent positive electrode active material cannot be pulped due to the high residual alkali content. And the secondary sintering can release the stress accumulated in the material again, so that the stress of the material itself is in the optimal state.

[0093] In an alternative embodiment, S2 and S3 further comprise mixing the active intermediate with a second additive containing M; introducing the additive twice and sintering can improve the capacity performance.

[0094] Optionally, M in the first and second additives is independently selected from at least one of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, Sm;

[0095] Optionally, M in the first and second additives is selected from different elements.

[0096] In an alternative embodiment, M in the first additive is selected from at least two of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, Sm.

[0097] In an alternative embodiment, Ni accounts for 0.60-0.98 of the total moles of nickel, cobalt and manganese in the nickel-cobalt-manganese hydroxide precursor.

[0098] In an alternative embodiment, the lithium salt is selected from any one of lithium hydroxide monohydrate, lithium nitrate, lithium sulfate, lithium carbonate or anhydrous lithium hydroxide.

[0099] In an alternative embodiment, the lithium matching coefficient is 1:(1-1.08); optionally, 1:(1.01-1.06).

[0100] In an alternative embodiment, the M1-containing additive is an oxide, hydroxide, carbonate or acid of M1.

[0101] In an alternative embodiment, the M2-containing additive is an oxide, hydroxide, carbonate or acid of M2.

[0102] In an alternative embodiment, the time for the first sintering is 8-26h, and optionally 8-24h.

[0103] In an alternative embodiment, the second sintering is performed for 2-18 hours, alternatively 5-18 hours.

[0104] In an alternative embodiment, the first sintering is performed in air or oxygen atmosphere.

[0105] In an alternative embodiment, the second sintering is performed in air, oxygen or any mixture thereof, alternatively oxygen.

[0106] In an alternative embodiment, the first sintering is performed at a temperature of 700-800°C.

[0107] In an alternative embodiment, the second sintering is performed at a temperature of 250-650°C.

[0108] In a third aspect, the present application provides a positive electrode tab, comprising a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises the active material of the first aspect of the present application.

[0109] For example, the positive electrode current collector has two opposite surfaces in the thickness direction thereof, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0110] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0111] In some embodiments, the positive electrode film layer can further include a binder. For example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic ester resin.

[0112] In some embodiments, the positive electrode film layer can further include a conductive agent. For example, the conductive agent can include at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0113] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector; and subjecting the positive electrode current collector to drying, cold pressing, and the like to obtain the positive electrode sheet.

[0114] In a fourth aspect, the present application also provides a secondary battery comprising the positive electrode sheet of the third aspect.

[0115] The secondary battery of the present application is described below.

[0116] [Positive electrode sheet]

[0117] The negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer comprising a negative electrode active material.

[0118] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0119] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. As a metal foil, for example, a copper foil can be used. The composite current collector can comprise a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base layer (such as a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0120] In some embodiments, the negative electrode active material can be a negative electrode active material known in the art for use in a battery. As an example, the negative electrode active material can comprise at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material for a battery can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0121] In some embodiments, the negative electrode film layer further optionally comprises a binder. The binder can 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).

[0122] In some embodiments, the negative electrode film layer further optionally comprises a conductive agent. The conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0123] In some embodiments, the negative electrode film layer further optionally comprises other auxiliary agents, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), etc.

[0124] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry on a negative electrode current collector, and after processes such as drying, cold pressing, etc., a negative electrode sheet is obtained.

[0125] [Electrolyte]

[0126] The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The type of electrolyte is not specifically limited in the present application and can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0127] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution comprises an electrolyte salt and a solvent.

[0128] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobisoxalate borate, lithium bisoxalate borate, lithium difluorobisoxalate phosphate, and lithium tetrafluorobisoxalate phosphate.

[0129] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl 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, butane sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0130] In some embodiments, the electrolyte can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive that can improve certain properties of the battery, such as an additive that improves overcharge performance of the battery, an additive that improves high or low temperature performance of the battery, etc.

[0131] The lithium ion solid-state electrolyte can be various lithium ion solid-state electrolytes commonly used in the art.

[0132] In some of the embodiments, the solid-state electrolyte substrate is a lithium ion solid-state electrolyte.

[0133] The lithium ion solid-state electrolyte is exemplified herein, including but not limited to:

[0134] LISICON type: such as γ-Li3PO4, etc.;

[0135] NASICON type; such as Li (1+x1) Q x1 M (2-x1) (PO4)3, 0≤x1<1, Q includes at least one of Al, Cr, Ba, Fe, Sc, In, Lu, Y, La;

[0136] Garnet type; such as Li (7-x2) La3Zr (2-x2) M x2 O12, etc., 0≤x2<1, M includes at least one of Sb, Nb, Ta, Te, W;

[0137] LIPON type: such as Li x3 PO y1 N z1 ; 0<x3≤1, 0<y1≤1, 0<z1≤1;

[0138] Perovskite type: such as Li x4 Q (2 / 3-x4) MO3, etc., 0.04<x4<0.17, Q includes at least one of La, Sr, Ba, Nd, M includes at least one of Al, Ti, Ge;

[0139] Anti-Perovskite type: such as Li3OCl, etc.;

[0140] Thio-LiSICON type: such as Li (3+x5) My2A (1-y2) Q (4-z2) T z2wherein -1 < x5 < 2, 0 < y2 < 1, 0 < z2 < 2, M comprises at least one of B, Al, In, Si, Ge, Sn, Ti, W, Mo, A comprises at least one of P, As, Sb, Bi, Q comprises at least one of S, Se, T comprises at least one of F, Cl, Br, I;

[0141] Sulfide solid state electrolytes include: Thiophosphate type: Li3PS4, etc., Argyrodite type: Li6PS5Cl, Halide type: Li3InCl6, Hydride type: 0.7 Li(CB9H 10 ) - 0.3 Li(CB 11 H 12 ) at least one; for example Li (10+x6) M (1+y3) A (2-y3) Q (12-z3) H z3 type: wherein -2 < x6 < 2, 0 < y3 < 2, 0 < z3 < 2, M comprises at least one of B, Al, In, Si, Ge, Sn, Ti, W, Mo, A comprises at least one of P, As, Sb, Bi, Q comprises at least one of S, Se, H comprises at least one of F, Cl, Br, I: (100-x7)Li2S-x7M-y4Q type: wherein 20 < x7 < 30, 0 < y4 < 50, M comprises at least one of B2S3, Al2S3, In2S3, SiS2, GeS2, SnS2, P2S5, As2S3, Sb2S5, Bi2S3, WS2, MoS2, Q comprises at least one of B2O3, Al2O3, In2O3, SiO2, GeO2, SnO2, P2O5, Sb2O5, Bi2O3, WO2, WO3, MoO2, MoO3, Fe2O3, ZnO, MgO, CuO, CaO, LiN, Li2O, LiF, LiCl, LiBr, LiI; Argyrodite type: Li (6+x8) M y5 A (1-y5) Q (5-z5) T (1+z5) wherein -1 < x8 < 1, 0 < y5 < 1, -1 < z5 < 1, M comprises at least one of B, Al, In, Si, Ge, Sn, Ti, W, Mo, A comprises at least one of P, As, Sb, Bi, Q comprises at least one of S, Se, T comprises at least one of F, Cl, Br, I; Halide type: Li3MJ or Li2Sc 2 / 3 J; M comprises at least one of Y, Er, In, Sc, Ga, J comprises at least one of F, Cl, Br, I.

[0142] The sulfide solid electrolyte, when being a sulfide-type solid electrolyte, includes, but is not limited to, argyrodite electrolyte; binary sulfide-type solid systems such as Li2S-P2S5, Li2S-SiS2, Li2S-GeS, and Li2S-B2S3, and a ternary system Li2S-Me-P2S5, wherein Me is selected from Si, Ge, Sn, or Al.

[0143] Specifically, the sulfide electrolyte is selected from at least one of Li2S-P2S5, Li2S-SiS2, Li2S-GeS, Li2S-B2S3, and Li2S-Me-P2S5.

[0144] [Separator]

[0145] In some embodiments, the secondary battery further comprises a separator. The type of the separator is not particularly limited in the present application, and any known porous structure separator having good chemical stability and mechanical stability can be used.

[0146] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0147] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be used to make an electrode assembly by a winding process or a stacking process.

[0148] In some embodiments, the secondary battery can comprise an outer package. The outer package can be used to package the electrode assembly and the electrolyte.

[0149] In some embodiments, the outer package of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and as the plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate, etc. can be listed.

[0150] The shape of the secondary battery is not particularly limited in the present application, and the secondary battery can be cylindrical, square, or any other shape.

[0151] In some embodiments, the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0152] In some embodiments, the above battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0153] In a fifth aspect, the present application provides a power consumption device comprising the above secondary battery.

[0154] In some embodiments, the above power consumption device can also include a battery module or a battery pack assembled from the above secondary battery. The secondary battery, the battery module, or the battery pack can be used as a power source of the power consumption device, and can also be used as an energy storage unit of the power consumption device. The power consumption device can include but is not limited to mobile devices (such as mobile phones, notebook computers, 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.

[0155] As the power consumption device, the secondary battery, the battery module or the battery pack can be selected according to the use requirements thereof. As an example of the power consumption device, a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc., in order to meet the requirements of high power and high energy density of the secondary battery for the power consumption device, a battery pack or a battery module can be used.

[0156] As another example of the device, it can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and a secondary battery can be used as a power source.

[0157] The present application will be further described in detail below in combination with specific embodiments, which cannot be understood as limiting the scope of the present application.

[0158] In the present application, the nickel-cobalt-manganese hydroxide precursor Ni 0.96 Co 0.03 Mn 0.01 (OH)2(model ZWN9607B), Ni 0.90 Co 0.05 Mn 0.05 (OH)2are all from Hunan Zhongwei New Material, and the median particle size is 10 um.

[0159] Example 1

[0160] The present embodiment provides a preparation method of a positive electrode active material, comprising the following steps:

[0161] S1, 500.00 g of nickel-cobalt-manganese hydroxide precursor Ni 0.96 Co 0.03 Mn 0.01(OH)2, 1.423 g nano-ZrO2 and 0.89 g of SrCO3 were premixed, 232.58 g of lithium hydroxide monohydrate was weighed according to the lithium ratio of 1.03, and mixed uniformly in a high-speed mixer, and then placed in an oxygen furnace at 705°C for sintering for 20 h. After crushing and sieving, the active intermediate was obtained.

[0162] S2, 0.63 g of WO3 was weighed and added to 500 g of the active intermediate, mixed uniformly in a high-speed mixer, placed in an oxygen furnace at 450°C for sintering for 7 h, cooled to room temperature in the furnace, and sieved to obtain the positive electrode active material.

[0163] Example 2

[0164] The embodiment provides a preparation method of a positive electrode active material, including the following steps:

[0165] S1, 500.00 g of a nickel-cobalt-manganese hydroxide precursor Ni 0.96 Co 0.03 Mn 0.01 (OH)2, 1.423 g nano-ZrO2 and 0.89 g of SrCO3 were premixed, 232.58 g of lithium hydroxide monohydrate was weighed according to the lithium ratio of 1.03, and mixed uniformly in a high-speed mixer, and then placed in an oxygen furnace at 705°C for sintering for 20 h. After crushing and sieving, the active intermediate was obtained.

[0166] S2, 0.63 g of WO3 was weighed and added to 500 g of the active intermediate, mixed uniformly in a high-speed mixer, placed in an oxygen furnace at 450°C for sintering for 7 h, cooled to room temperature in the furnace, and sieved to obtain the positive electrode active material.

[0167] Example 3

[0168] The embodiment provides a preparation method of a positive electrode active material, including the following steps:

[0169] S1, 500.00 g of a nickel-cobalt-manganese hydroxide precursor Ni 0.96 Co 0.03 Mn 0.01 (OH)2, 1.423 g nano-ZrO2 and 0.89 g of SrCO3 were premixed, 232.58 g of lithium hydroxide monohydrate was weighed according to the lithium ratio of 1.03, and mixed uniformly in a high-speed mixer, and then placed in an oxygen furnace at 705°C for sintering for 20 h. After crushing and sieving, the active intermediate was obtained.

[0170] S2, 0.63 g of WO3 was weighed and added to 500 g of the active intermediate, mixed uniformly in a high-speed mixer, placed in an oxygen furnace at 450°C for sintering for 7 h, cooled to room temperature in the furnace, and sieved to obtain the positive electrode active material.

[0171] Example 4

[0172] The embodiment provides a preparation method of a positive electrode active material, and comprises the following steps:

[0173] S1, 500.00 g of a nickel-cobalt-manganese hydroxide precursor Ni 0.96 Co 0.03 Mn 0.01 (OH)2, 0.075 g of nano-Nb2O5 and 0.445 g of SrO are premixed, 233.32 g of lithium hydroxide monohydrate is weighed according to a lithium matching coefficient of 1.02, and then uniformly mixed in a high-speed mixer, and then placed in an oxygen furnace at 725 DEG C for sintering for 10 h; after crushing and sieving, an active intermediate is obtained.

[0174] S2, 0.307 g of CeO2 is weighed and added to 500 g of the active intermediate, uniformly mixed in a high-speed mixer, placed in an oxygen furnace at 500 DEG C for sintering for 5 h, cooled to room temperature with the furnace, and sieved to obtain a positive electrode active material.

[0175] Example 5

[0176] The embodiment provides a preparation method of a positive electrode active material, and comprises the following steps:

[0177] S1, 500.00 g of a nickel-cobalt-manganese hydroxide precursor Ni 0.96 Co 0.03 Mn 0.01 (OH)2, 1.423 g of nano-ZrO2 and 0.89 g of SrCO3 are premixed, 232.58 g of lithium hydroxide monohydrate is weighed according to a lithium matching coefficient of 1.03, and then uniformly mixed in a high-speed mixer, and then placed in an oxygen furnace at 600 DEG C for sintering for 26 h; after crushing and sieving, an active intermediate is obtained.

[0178] S2, 0.63 g of WO3 is weighed and added to 500 g of the active intermediate, uniformly mixed in a high-speed mixer, placed in an oxygen furnace at 800 DEG C for sintering for 2 h, cooled to room temperature with the furnace, and sieved to obtain a positive electrode active material.

[0179] Example 6

[0180] The embodiment provides a preparation method of a positive electrode active material, and comprises the following steps:

[0181] S1, 500.00 g of a nickel-cobalt-manganese hydroxide precursor Ni 0.96 Co 0.03 Mn 0.01(OH)2, 1.423g of nano ZrO2 and 0.89g of SrCO3 were premixed, and then 132.73g of anhydrous lithium hydroxide was weighed according to the lithium ratio of 1.03. The mixture was mixed evenly in a high-speed mixer and placed in an oxygen furnace at 800℃ for 8 hours. After crushing and sieving, the active intermediate was obtained.

[0182] S2. Weigh 0.63g WO3 and add it to 500g of active intermediate. Mix evenly in a high-speed mixer and place in an oxygen furnace at 200℃ for sintering for 18h. Cool to room temperature with the furnace and sieve to obtain positive electrode active material.

[0183] Example 7

[0184] This embodiment provides a method for preparing a positive electrode active material, including the following steps:

[0185] S1, 500.00g of nickel-cobalt-manganese hydroxide precursor Ni 0.90 Co 0.05 Mn 0.05 (OH)2, 1.423g of nano ZrO2 and 0.89g of SrCO3 were premixed, and then 232.58g of lithium hydroxide monohydrate was weighed according to the lithium ratio of 1.03. The mixture was mixed evenly in a high-speed mixer and placed in an oxygen furnace at 735℃ for 20h for sintering. After crushing and sieving, the active intermediate was obtained.

[0186] S2. Weigh 0.63g WO3 and add it to 500g of active intermediate. Mix evenly in a high-speed mixer and place in an oxygen furnace at 450℃ for sintering for 7 hours. Cool to room temperature with the furnace and sieve to obtain the positive electrode active material.

[0187] Example 8

[0188] This embodiment provides a method for preparing a positive electrode active material, including the following steps:

[0189] S1, 500.00g of nickel-cobalt-manganese hydroxide precursor Ni 0.96 Co 0.03 Mn 0.01 (OH)2, 1.423g nano ZrO2, 0.89g SrCO3 and 0.66g WO3 were premixed, and then 232.58g lithium hydroxide monohydrate was weighed according to the lithium ratio of 1.03. The mixture was mixed evenly in a high-speed mixer and placed in an oxygen furnace at 705℃ for 20h for sintering. After crushing and sieving, the active intermediate was obtained.

[0190] S2. The active intermediate was sintered in an oxygen furnace at 450°C for 7 hours, cooled to room temperature with the furnace, and then sieved to obtain the positive electrode active material.

[0191] Example 9

[0192] The embodiment provides a preparation method of a positive electrode active material, and comprises the following steps:

[0193] S1, 500.00 g of nickel-cobalt-manganese hydroxide precursor Ni 0.96 Co 0.03 Mn 0.01 (OH)2, 2.10 g of nano ZrO2 is premixed, 232.58 g of lithium hydroxide monohydrate is weighed according to a lithium matching coefficient of 1.03, and then uniformly mixed in a high-speed mixer, and then placed in an oxygen furnace at 705 DEG C for sintering for 20 h, and then crushed and sieved to obtain an active intermediate.

[0194] S2, the active intermediate is placed in an oxygen furnace at 450 DEG C for sintering for 7 h, cooled to room temperature with the furnace, and sieved to obtain a positive electrode active material.

[0195] Comparative Example 1

[0196] The comparative example provides a preparation method of a positive electrode active material, and comprises the following steps:

[0197] S1, 500.00 g of nickel-cobalt-manganese hydroxide precursor Ni 0.96 Co 0.03 Mn 0.01 (OH)2 and 232.58 g of lithium hydroxide monohydrate are uniformly mixed in a high-speed mixer, and then placed in an oxygen furnace at 705 DEG C for sintering for 20 h, and then crushed and sieved to obtain an active intermediate.

[0198] S2, sintering in an oxygen furnace at 450 DEG C for 7 h, cooling to room temperature with the furnace, and sieving to obtain a positive electrode active material.

[0199] Comparative Example 2

[0200] The comparative example provides a preparation method of a positive electrode active material, and the comparative example is basically the same as the embodiment 1, and the difference lies in that, in the comparative example, the conditions of the first sintering are sintering in an oxygen furnace at 825 DEG C for 20 h.

[0201] Table 1 test conditions of the embodiment and the comparative example

[0202] The lithium matching coefficient is the molar ratio of Li to the total amount of transition metals.

[0203] Test Example

[0204] 1, the parameters of the positive electrode active materials prepared in the embodiment and the comparative example are tested:

[0205] 1) The volume particle size median D50 of the positive electrode active material is determined by referring to the standard GB / T19077-2016 and using a laser particle size analyzer (Malvern Master Size 2000).

[0206] 2) The specific surface area of the positive electrode active material was tested using a specific surface area analyzer (JW-BK400) in accordance with GB / T 19587-2017.

[0207] 3) The surface residual alkali content of the positive electrode active material was tested using a potential titrator (Mettohm 905) in accordance with GB / T41704-2022.

[0208] 4) The crystal diffraction peak information of the positive electrode active material was tested using an X-ray powder diffractometer (Malvern panalytical A series) in accordance with the industry standard JY / T0587-2020, and D(104) was calculated based on the test data and the Scherrer formula.

[0209] 5) The surface particle size ND50, ND90, ND10 of the positive electrode active material were measured by selecting the secondary particles with a median particle size D50 at ×30000 times using a field emission scanning electron microscope (Zeiss Gemini series), and using the image recognition tool of the electron microscope.

[0210] The test results are shown in Table 2 and Figures 1-3.

[0211] Table 2 Physical parameters of the positive electrode active material

[0212] Figure 1 is a scanning electron microscope image of the positive electrode active material of Example 1. The particles with a median particle size of 10 um were observed by field emission scanning electron microscopy, and the morphology of the surface particles was square-like. Image recognition technology was used to analyze the size and form a normal distribution result, as shown in Figure 3. It was found through calculation that the distribution rate Φ of the surface particles was 0.44, indicating that the particle size deviated from the average number 477 nm very little, further proving the uniformity of the primary particle distribution.

[0213] Figure 2 is an XRD pattern of the positive electrode active material of Example 1. The strongest diffraction peak between 43-47° is the (104) crystal face diffraction peak. Through formula calculation, the value of the stacking thickness γ of the positive electrode active material in the (104) direction was 7.75. The thickness of this direction is related to the strength of the particles, and controlling this index within an appropriate range can significantly improve the compression stress test life of the particles.

[0214] 2. The positive electrode active materials prepared in the examples and comparative examples were placed in an atomic force microscope (Bruker Multimode 8-HR), and the NanoScope operation software was used to set the pressure of the probe at 0.2-0.6 Gpa, and the reciprocating compression stress test was carried out until the stress mutation, i.e. the reciprocating number when the secondary particles were broken, was recorded as the compression stress test life.

[0215] 3. The positive electrode active materials prepared in Examples and Comparative Examples were mixed with conductive agent (SP) and PVDF in a mass ratio of 96.0:2.0:2.0, and coated on aluminum foil to prepare positive electrode sheets. Graphite negative electrode material, conductive agent (SP), CMC and SBR were mixed in a mass ratio of 95.5:1.0:1.5:2, and coated on copper foil to prepare negative electrode sheets, and the N / P ratio was 1.15. The electrolyte was NaPF6 electrolyte (NP-202). The negative electrode sheet, separator and positive electrode sheet were wound and placed in a 18650 cylindrical shell, electrolyte was injected, and a 18650 type cylindrical battery with a nominal capacity of 3000 mAh was prepared. In the voltage range of 2.8-4.35 V, the 1C / 5C charge-discharge cycle life test was performed in a thermostat at 45°C using a charge-discharge machine (Shenzhen Xinwei BTS4000). The test was stopped when the battery capacity retention rate was 80% of the initial value, and the cycle number was recorded as the cycle life.

[0216] The test results are shown in Table 3.

[0217] Table 3 Positive electrode active material and battery performance

[0218] As can be seen from Table 3, the compressive stress life of the positive electrode active material prepared in the application is more than 50 times, which is significantly improved compared with the comparative examples. At the same time, the cycle life of the battery using the positive electrode active material of the application is also significantly improved. The uniform distribution of surface particles not only improves the compressive stress life of the particles, but also significantly improves the service life of the battery, which can bring huge economic benefits.

[0219] Figure 4 is a normal distribution curve of the particle size of the surface particles of the positive electrode active material of Example 1, Comparative Example 1 and Comparative Example 2. The main difference between Example 1 and Comparative Example 1 is the width of the normal distribution curve. The distribution rate Φ of the particles was quantified, and it was found that the distribution rate of Example 1 was 0.44, and the distribution rate of Comparative Example 1 reached 1.63. Combined with the compressive stress life test results of 70 times and 32 times respectively, it shows that the narrow distribution of once particles in Example 1 is beneficial to the release of internal stress of the particles, slows down the stress concentration phenomenon of the secondary spherical morphology, and further improves the material cracking caused by the uneven distribution of internal stress.

[0220] As can be seen from the comparison of Example 1, Example 5-Example 7, when 0.30≤Φ≤1.20 and 3≤γ≤15 are met, higher compressive stress life and cycle life can be obtained.

[0221] As can be seen from the comparison of Example 1, Example 8 and Example 9, after the first sintering, the active intermediate of Example 1 re-introduces the additives, and then performs the second sintering, compared with Example 8 which introduces all the additives before the first sintering, and Example 9 which only adds one high bonding energy element, can significantly reduce the residual alkali, improve the battery capacity and cycle life.

[0222] Obviously, the above examples are only examples for clearly illustrating, but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and also impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A positive electrode active material, characterized by, The positive electrode active material has a chemical formula of Li x Ni a Co b Mn 1-a-b M c O2, wherein 1≤x≤1.08, 0.6≤a≤0.98, 0 The positive electrode active material has a chemical formula of Li x Ni a Co b Mn 1-a-b M c O2, wherein 1≤x≤1.08, 0.6≤a≤0.98, 0 The positive electrode active material has a chemical formula of Li x Ni a Co b Mn 1-a-b M c O2, wherein 1≤x≤1.08, 0. The positive electrode active material satisfies the following relational expression: Φ is a distribution rate of surface particles, the surface particles are primary particles on a surface of secondary particles; ND10 is a particle size corresponding to a cumulative particle size distribution percentage of 10% of surface particles, ND50 is a particle size corresponding to a cumulative particle size distribution percentage of 50% of surface particles, and ND90 is a particle size corresponding to a cumulative particle size distribution percentage of 90% of surface particles; γ is a stacking thickness in a direction of the positive electrode active material (104), and D(104) is a grain size in the direction of the positive electrode active material (104).

2. The positive electrode active material according to claim 1, characterized by 0.30≤Φ≤1.

20.

3. The positive electrode active material according to claim 1, characterized by 3≤γ≤15.

4. The positive electrode active material according to claim 1, characterized by ND50 is 270-800 nm, and optionally, ND50 is 400-700 nm.

5. The positive electrode active material according to claim 1, characterized by ND90 is 300-2000 nm, and optionally, ND90 is 500-1800 nm.

6. The positive electrode active material according to claim 1, characterized by ND10 is 50-500 nm, and optionally, ND10 is 100-400 nm.

7. The positive electrode active material according to claim 1, characterized by D(104) is 35-150 nm, and optionally, D(104) is 45-120 nm.

8. The positive electrode active material according to any one of claims 1 to 7, characterized by, M is selected from at least one of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, and Sm; Optionally, M is selected from at least two of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, and Sm. Optionally, 0.80≤a≤0.

98. Optionally, 0.005≤c≤0.

025.

9. The positive electrode active material according to any one of claims 1 to 7, characterized by, The positive electrode active material satisfies at least one of the following conditions: (1) a specific surface area of 0.2 to 1.2 m 2 / g, optionally 0.4 to 0.8 m 2 / g; (2) a surface residual alkali content satisfies Li2CO3≤6000 ppm and LiOH≤8000 ppm; optionally, Li2CO3≤4000 ppm and LiOH≤6000 ppm; (3) a particle size median D50 of the positive electrode active material is 2.0-25.0 μm, and optionally, 3.0-18.0 μm.

10. A method for producing a positive electrode active material, characterized by, The method comprises the following steps: S1, mixing a lithium salt, a first additive containing M, and a nickel-cobalt-manganese hydroxide precursor to obtain a mixture; S2, performing primary sintering on the mixture at 600-800 ℃ to obtain an active intermediate; S3, performing secondary sintering on the active intermediate at 200-800 ℃ to obtain a positive electrode active material; The binding energy of M and oxygen is more than 2 times of the lithium-oxygen bond binding energy.

11. The method of producing a positive electrode active material according to claim 10, characterized by, S2 and S3 further comprise mixing the active intermediate with a second additive containing M; Optionally, M in the first additive and the second additive is independently selected from at least one of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, and Sm. Optionally, M in the first additive and the second additive is selected from different elements.

12. The method of producing a positive electrode active material according to claim 10 or 11, characterized by, M in the first additive is selected from at least two of Bi, Sr, B, Ti, Al, Y, Zr, Sb, Ta, Nb, Mo, La, W, Ce, and Sm.

13. A method for producing the positive electrode active material according to claim 10 or 11, characterized by, Satisfies at least one of the following conditions: (1) Ni accounts for 0.60-0.98 of a total molar amount of nickel, cobalt, and manganese in the nickel-cobalt-manganese hydroxide precursor; (2) the lithium salt is selected from any one of lithium hydroxide monohydrate, lithium nitrate, lithium sulfate, lithium carbonate or anhydrous lithium hydroxide; (3) the lithium matching coefficient is 1:(1-1.08); optionally 1:(1.01-1.06); (4) the time of the first sintering is 8-26h, optionally 8-24h; (5) the time of the second sintering is 2-18h, optionally 5-18h; (6) the first sintering is performed in air or oxygen atmosphere; (7) the atmosphere of the second sintering is selected from any one of air, oxygen or a mixture of the two, optionally oxygen; (8) the temperature of the first sintering is 700-800℃; (9) the temperature of the second sintering is 250-650℃.

14. A positive electrode sheet characterized by comprising: comprising: a positive electrode current collector, and a positive electrode film layer disposed on at least one side of the positive electrode current collector, the positive electrode film layer comprising the positive electrode active material of any one of claims 1-9 or the positive electrode active material prepared according to the method of any one of claims 10-13.

15. A secondary battery characterized by comprising: comprising the positive electrode tab of claim 14.

16. An electrical device, comprising: comprising the secondary battery of claim 15.

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