High-nickel positive electrode material and preparation method thereof, secondary battery

Abstract

The application relates to a high-nickel positive electrode material and a preparation method thereof, and a secondary battery, the high-nickel positive electrode material comprising primary particles and a composite coating layer coated on at least part of the surfaces of the primary particles, wherein the composite coating layer comprises a conductive matrix, the conductive matrix is formed with pores, and the pores are dispersed with coating materials. In the composite coating layer of the high-nickel positive electrode material, the conductive matrix with the pore structure can form a conductive grid, and the coating materials are embedded in the conductive grid. On the one hand, the conductive matrix and the coating materials are distributed in the same coating layer, which can improve the conductivity of the positive electrode material and block the direct contact between the positive electrode material and the electrolyte. On the other hand, the coating materials are filled in the conductive grid, which can form a stable electrochemical interface. The high-nickel positive electrode material can consider the problems of the electrochemical interface stability and the conductivity, so that the energy density, the cycle performance and the safety performance of the high-nickel positive electrode material are improved.

Description

Technical Field

[0001] This application belongs to the field of cathode material technology, and more specifically, relates to a high-nickel cathode material and its preparation method, and a secondary battery. Background Technology

[0002] Rechargeable batteries are widely used in laptops, mobile phones, and digital products due to their high energy density, good safety performance, long cycle life, and environmental friendliness. Simultaneously, with increasing environmental awareness, rechargeable batteries are gradually being used as power batteries in transportation vehicles, such as electric vehicles and electric buses. The market is placing increasingly higher demands on the specific capacity, energy density, power density, and lifespan of rechargeable batteries, especially specific capacity. The most commonly used cathode materials in rechargeable batteries are olivine-structured LiFePO4, layered LiCoO2, and layered lithium nickel oxide materials. Olivine-structured LiFePO4 has reached its capacity limit and its main applications are in energy storage and low-range electric vehicles. Layered LiCoO2 is mainly used in consumer batteries. Lithium nickel oxide materials are widely used in electric vehicles. In lithium nickel oxide materials, nickel is the main redox reaction element; increasing the nickel content can effectively improve the specific capacity of these materials, thus the development of high-nickel materials has become a market trend.

[0003] Current high-nickel ternary cathode materials exhibit a large amount of Ni with strong oxidizing and catalytic activity on their surface during charging. 4+ This leads to instability at the electrochemical interface, continuous consumption of electrolyte, and degradation of electrochemical performance. Although this problem can be solved by coating the electrode material with a chemically and electrochemically stable material, the increase in coating often means a decrease in the conductivity of the cathode material, which will directly affect the battery capacity and rate performance of the cathode material.

[0004] Currently, there is an urgent need for a high-nickel cathode material with high electrochemical interface stability and high conductivity. Summary of the Invention

[0005] In order to overcome the above-mentioned defects, this application provides a high-nickel cathode material, its preparation method, and a secondary battery, which can improve the electrochemical interface stability of the cathode material while improving its conductivity.

[0006] In a first aspect, embodiments of this application provide a high-nickel cathode material, the high-nickel cathode material comprising a high-nickel cathode material substrate and a composite coating layer covering at least a portion of the surface of the high-nickel cathode material substrate, the composite coating layer comprising a conductive substrate, the conductive substrate having pores, and the coating material being dispersed within the pores.

[0007] In some embodiments, the high-nickel cathode material includes at least one of the following features (1) to (11):

[0008] (1) The conductivity of the conductive substrate is greater than that of the coating material;

[0009] (2) The conductive substrate is made of transition metal oxides;

[0010] (3) The conductive substrate is made of transition metal oxides, and the conductive substrate is made of at least one of indium tin oxide, antimony tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, gallium-doped zinc oxide, cuprous aluminate and tin oxide;

[0011] (4) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides, and fast ion conductors;

[0012] (5) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides and fast ion conductors, wherein the carbon-based material includes at least one of activated carbon, graphite and graphene;

[0013] (6) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides and fast ion conductors, and the metal oxide includes at least one of TiO2, Al2O3, Bi2O3, ZnO, SiO2 and ZrO2;

[0014] (7) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides and fast ion conductors, wherein the metal phosphate includes at least one of AlPO4, Co3(PO4)2 and Ni3(PO4)2;

[0015] (8) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides and fast ion conductors, wherein the metal fluoride includes at least one of AlF3, YF3 and CuF2;

[0016] (9) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides and fast ion conductors, wherein the fast ion conductor includes at least one of Li2O-2B2O3, Li2TiO3 and Li2ZrO3;

[0017] (10) The thickness of the composite coating layer is 0.5 nm to 200 nm;

[0018] (11) The average pore size of the hole is 10nm to 200nm.

[0019] In some embodiments, the general chemical formula of the high-nickel cathode material is shown in formula (Ⅰ):

[0020] LiNi x Co y Mn z @A / B(Ⅰ)

[0021] In equation (Ⅰ), 0.8 ≤ x < 1, 0 < y ≤ 0.12, 0 < z ≤ 0.08, and x + y + z = 1, the LiNi x Co y Mn z The chemical formula of the high-nickel cathode material matrix is ​​given, wherein A / B is distributed in the LiNi... x Co y Mn z The surface of A includes transition metal oxides, and B includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides, and fast ion conductors.

[0022] In some embodiments, the high-nickel cathode material includes at least one of the following features (1) to (2):

[0023] (1) The specific surface area of ​​the high-nickel cathode material is 0.3 m². 2 / g~3m 2 / g;

[0024] (2) The conductivity of the high-nickel cathode material is 10. -1 S / cm~10 2 S / cm.

[0025] Secondly, embodiments of this application provide a method for preparing a high-nickel cathode material, comprising the following steps:

[0026] A mixture containing block copolymers and conductive materials is mixed with a high-nickel cathode material matrix and then subjected to a first heat treatment to obtain a high-nickel cathode material matrix with a conductive material coating on its surface. The surface of the high-nickel cathode material matrix with the conductive material coating has a mesh structure.

[0027] The mixture containing the coating material is mixed with the high-nickel cathode material matrix coated with the conductive material on the surface, and then subjected to a second heat treatment to obtain the high-nickel cathode material.

[0028] In some embodiments, the preparation method includes at least one of the following features (1) to (13):

[0029] (1) The block copolymer includes at least one of diblock copolymers and multiblock copolymers;

[0030] (2) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction;

[0031] (3) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the first monomer includes at least one of N,N dimethylacrylamide, styrene, 1,3-butadiene, acrylate and ethylene oxide;

[0032] (4) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the second monomer includes at least one of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid, benzyl methacrylate, diethylaminoethyl methacrylate and isobutyl vinyl ether;

[0033] (5) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the initiator includes at least one of azobisisobutyronitrile (AIBN), acetal / trimethyl iodide, acetic acid and di-tert-butyl peroxide;

[0034] (6) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the first solvent includes at least one of 1,4-dioxane, n-hexane, methanol and acetone;

[0035] (7) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the mass ratio of the first monomer to the second monomer is 1:(0.001~0.1);

[0036] (8) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the mass ratio of the total mass of the first monomer and the second monomer to the mass of the first solvent is 1:(0.5-10);

[0037] (9) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction at a temperature of 50°C to 90°C.

[0038] (10) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction for 1 h to 6 h.

[0039] (11) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the oil bath reaction is carried out in an inert gas atmosphere;

[0040] (12) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, and finally quenching, dissolving, precipitating, filtering and drying the mixture after the oil bath reaction.

[0041] (13) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, and finally quenching, dissolving, precipitating, filtering and drying the mixture after the oil bath reaction, wherein the solvent for dissolution includes acetone.

[0042] In some embodiments, the preparation method includes at least one of the following features (1) to (12):

[0043] (1) The conductive material includes transition metal oxides;

[0044] (2) The conductive material includes a transition metal oxide, which includes at least one of indium tin oxide, antimony tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, gallium-doped zinc oxide, cuprous aluminate, and tin oxide.

[0045] (3) The mass ratio of the block copolymer to the conductive material is 1:(0.1~10);

[0046] (4) The mixture containing block copolymer and conductive material further includes a second solvent;

[0047] (5) The mixture containing block copolymer and conductive material further includes a second solvent, the second solvent including at least one of N,N-dimethylformamide, propylamine, dimethylamine and diethyl ether;

[0048] (6) The chemical formula of the high-nickel cathode material matrix is: LiNi x Co y Mn z Where 0.8≤x<1, 0<y≤0.12, 0<z≤0.08, x+y+z=1;

[0049] (7) The mass ratio of the conductive material to the high-nickel cathode material matrix is ​​1:(100~10000);

[0050] (8) The mixing process is carried out under the first stirring condition;

[0051] (9) The mixing process is carried out under the first stirring condition, where the stirring speed is 10 r / min to 100 r / min;

[0052] (10) The mixing process is carried out under the first stirring condition, and the time of the first stirring condition is 30s to 300s.

[0053] (11) The temperature of the first heat treatment is 200℃~500℃;

[0054] (12) The first heat treatment time is 1h to 12h.

[0055] In some embodiments, the mixture containing the coating material is prepared according to the following steps: adding the coating material and a third solvent to a dispersant, wherein the preparation method includes at least one of the following features (1) to (14):

[0056] (1) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides and fast ion conductors;

[0057] (2) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides, and fast ion conductors, wherein the carbon-based material includes at least one of activated carbon, graphite, and graphene.

[0058] (3) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides and fast ion conductors, and the metal oxide includes at least one of TiO2, Al2O3, Bi2O3, ZnO, SiO2 and ZrO2;

[0059] (4) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides and fast ion conductors, wherein the metal phosphate includes at least one of AlPO4, Co3(PO4)2 and Ni3(PO4)2;

[0060] (5) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides and fast ion conductors, and the metal fluoride includes at least one of AlF3, YF3 and CuF2;

[0061] (6) The coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides and fast ion conductors, wherein the fast ion conductor includes at least one of Li2O-2B2O3, Li2TiO3 and Li2ZrO3;

[0062] (7) The third solvent includes at least one of ethanolamine, ethylenediamine, propylamine and triethylamine;

[0063] (8) The dispersant includes at least one of ethanol, acetone, methanol and ethyl acetate;

[0064] (9) The volume ratio of the third solvent to the dispersant is 1:(10~10000);

[0065] (10) The mass ratio of the coating material to the high-nickel cathode material matrix is ​​1:(100~10000);

[0066] (11) The mass ratio of the coating material to the conductive material is 1:(0.1~10);

[0067] (12) The dispersion is carried out under the second stirring condition;

[0068] (13) The dispersion is carried out under the second stirring condition, wherein the stirring speed of the second stirring condition is 10 r / min to 100 r / min;

[0069] (14) The dispersion is carried out under the second stirring condition, and the time of the second stirring condition is 30s to 300s.

[0070] In some embodiments, the preparation method includes at least one of the following features (1) to (6):

[0071] (1) The mixing of the mixture containing the coating material and the high-nickel cathode material matrix with the surface coated conductive material are carried out under the third stirring condition;

[0072] (2) The mixing of the mixture containing the coating material and the high-nickel cathode material matrix with the surface coated conductive material is carried out under the third stirring condition; the stirring speed of the third stirring condition is 10 r / min to 100 r / min;

[0073] (3) The mixing of the mixture containing the coating material and the high-nickel cathode material matrix with the surface coated conductive material are carried out under the third stirring condition; the time of the third stirring condition is 30s to 300s.

[0074] (4) The temperature of the second heat treatment is 600℃~900℃;

[0075] (5) The second heat treatment time is 15h to 30h;

[0076] (6) The second heat treatment is carried out in an oxygen atmosphere.

[0077] Thirdly, embodiments of this application provide a secondary battery, the secondary battery comprising the high-nickel cathode material described in the first aspect or the high-nickel cathode material prepared by the preparation method described in the second aspect.

[0078] The technical solution of this application has at least the following beneficial effects:

[0079] In the composite coating layer of the high-nickel cathode material of this application, the porous conductive substrate can form a conductive grid, and the coating material is embedded in the conductive grid. On the one hand, the conductive substrate and the coating material are distributed in the same coating layer, which can improve the conductivity of the cathode material and block the direct contact between the cathode material and the electrolyte; on the other hand, the coating material filling the conductive grid can form a stable electrochemical interface. The high-nickel cathode material of this application can solve the problems of electrochemical interface stability and conductivity, thereby improving the energy density, cycle performance and safety performance of the high-nickel cathode material.

[0080] This application involves coating a high-nickel cathode material matrix with a mixture containing block copolymers and conductive materials, followed by a first heat treatment. During this first heat treatment, the block copolymers decompose at high temperatures, forming pores and creating a mesh-like structure on the surface of the high-nickel cathode material matrix. Finally, a second heat treatment is applied to the coating material and the mesh-like high-nickel cathode material matrix, causing the coating material to fill within the mesh structure. This results in a high-nickel cathode material that simultaneously exhibits good conductivity and electrolyte resistance. This application utilizes a wet processing method to coat the high-nickel cathode material surface with a composite coating layer formed by the conductive and coating materials. The process is simple and effectively improves the specific capacity, cycle performance, and safety performance of the high-nickel cathode material. Compared to high-nickel cathode materials obtained by directly mixing a mixture of conductive and coating materials with a high-nickel cathode material matrix and then heat-treating, this application's high-nickel cathode material forms a continuous conductive mesh, significantly enhancing the conductivity of the cathode material. Attached Figure Description

[0081] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0082] Figure 1 This is a flowchart of the preparation method of the high-nickel cathode material of this application;

[0083] Figure 2 This is a SEM image of the high-nickel cathode material of Example 1 of this application;

[0084] Figure 3 Comparison of charge-discharge curves of high-nickel cathode materials prepared in Examples 1, 2, 1, and 2. Detailed Implementation

[0085] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0086] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0087] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0088] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0089] In existing technologies, in order to alleviate the Ni content in high-nickel cathode materials... 4+ This can lead to problems such as unstable electrochemical interfaces and continuous consumption of electrolyte. Usually, a double-layer coating method is used to improve the stability of the material surface. However, the presence of the coating material makes the conductivity of high-nickel cathode materials poor, resulting in lower energy density and cycle performance of the cathode material.

[0090] Therefore, this application provides a high-nickel cathode material, which includes a high-nickel cathode material substrate and a composite coating layer covering at least a portion of the surface of the high-nickel cathode material substrate. The composite coating layer includes a conductive substrate, which has pores, and the coating material is dispersed in the pores.

[0091] In the above-described scheme, the composite coating layer of the high-nickel cathode material of this application contains a porous conductive substrate that forms a conductive grid. The coating material is embedded in the conductive grid. On the one hand, the conductive substrate and the coating material are distributed in the same coating layer, and the conductive substrate can improve the conductivity of the cathode material. On the other hand, the coating material filling the conductive grid can form a stable electrochemical interface, blocking direct contact between the high-nickel cathode material substrate and the electrolyte. The high-nickel cathode material of this application can balance the issues of electrochemical interface stability and conductivity, thereby improving the energy density, cycle performance, and safety performance of the high-nickel cathode material.

[0092] In some embodiments, the conductivity of the conductive substrate is greater than that of the coating material.

[0093] In some embodiments, the conductive substrate is made of transition metal oxides, for example, at least one of indium tin oxide, antimony tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, gallium-doped zinc oxide, cuprous aluminate, and tin oxide.

[0094] In some embodiments, the coating material includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides, and fast ion conductors. Preferably, the coating material includes a metal oxide embedded in a transition metal oxide to form a composite coating layer. This structure is more dense and has higher conductivity compared to structures formed by other coating materials.

[0095] In some embodiments, the carbon-based material includes at least one of activated carbon, graphite, and graphene.

[0096] In some embodiments, the metal oxide includes at least one selected from TiO2, Al2O3, Bi2O3, ZnO, SiO2, and ZrO2;

[0097] In some embodiments, the metal phosphate includes at least one of AlPO4, Co3(PO4)2 and Ni3(PO4)2;

[0098] In some embodiments, the metal fluoride includes at least one of AlF3, YF3, and CuF2;

[0099] In some embodiments, the fast ion conductor includes at least one of Li₂O₂B₂O₃, Li₂TiO₃, and Li₂ZrO₃;

[0100] In some embodiments, the thickness of the composite coating layer is 0.5 nm to 200 nm. Specifically, the thickness of the composite coating layer can be, for example, 0.5 nm, 1 nm, 5 nm, 10 nm, 30 nm, 50 nm, 80 nm, 100 nm, 150 nm, and 200 nm, etc., and of course, other values ​​within the above range are also possible and are not limited here. Controlling the thickness of the composite coating layer within the above range can ensure that the composite coating layer forms a stable electrochemical interface without reducing the conductivity of the material. Preferably, the thickness of the composite coating layer is 5 nm to 50 nm. It can be understood that the conductive substrate forms the framework of the composite coating layer, that is, the thickness of the composite coating layer is the thickness of the conductive substrate.

[0101] In some embodiments, the average pore size is 10 nm to 200 nm. Specifically, the average pore size is 10 nm, 30 nm, 50 nm, 80 nm, 100 nm, 150 nm, and 200 nm, etc., and other values ​​within the above range are also possible and are not limited here. Limiting the average pore size to the above range is beneficial for the embedding of the coating material and improves the tap density of the material. Preferably, the thickness of the average pore size is 20 nm to 100 nm, and more preferably, the thickness of the average pore size is 5 nm to 50 nm.

[0102] In some embodiments, the general chemical formula of the high-nickel cathode material is shown in formula (1):

[0103] LiNi x Co y Mn z @A / B(1)

[0104] Where 0.8≤x<1, 0<y≤0.12, 0<z≤0.08, x+y+z=1, LiNi x Co y Mn zThe chemical formula for a high-nickel cathode material matrix is ​​given, with A / B distributed in LiNi. x Co y Mn z The surface of A includes transition metal oxides, and B includes at least one of carbon-based materials, metal oxides, metal phosphates, metal fluorides, and fast ion conductors.

[0105] In some implementations, the specific surface area of ​​the cathode material is 0.3 m². 2 / g~3m 2 / g, specifically, the specific surface area of ​​the cathode material can be 0.3m². 2 / g, 0.5m 2 / g, 0.7m 2 / g, 1.0m 2 / g, 1.3m 2 / g, 1.6m 2 / g, 2.0m 2 / g, 2.3m 2 / g, 2.6m 2 / g, 2.9m 2 / g and 3.0m 2 / g, etc., can also be other values ​​within the above range, and there are no restrictions here.

[0106] In some embodiments, the conductivity of the positive electrode material is 10. -1 S / cm~10 2 S / cm, specifically, the conductivity of the positive electrode material can be 10. -1 S / cm, 0.5S / cm, 1S / cm, 5S / cm, 10S / cm, 50S / cm and 100S / cm, etc., and of course other values ​​within the above range are also possible, without restriction.

[0107] This application also provides a method for preparing the above-mentioned high-nickel cathode material, such as... Figure 1 The diagram shown is a flowchart of the preparation method of the high-nickel cathode material of this application, including the following steps:

[0108] After mixing a mixture containing block copolymers and conductive materials with a high-nickel cathode material matrix, a first heat treatment is performed to obtain a high-nickel cathode material matrix with a conductive material coating on the surface. The surface of the high-nickel cathode material matrix with a conductive material coating has a mesh structure.

[0109] A mixture containing coating material is mixed with a high-nickel cathode material matrix coated with conductive material, and then subjected to a second heat treatment to obtain a high-nickel cathode material.

[0110] In the above-mentioned scheme, this application coats the surface of a high-nickel cathode material matrix with a mixture containing block copolymers and conductive materials, followed by a first heat treatment. The block copolymers decompose at high temperatures during the first heat treatment, forming pores and creating a mesh-like structure on the surface of the high-nickel cathode material matrix. Finally, the coating material and the mesh-like high-nickel cathode material matrix are subjected to a second heat treatment, causing the coating material to fill within the mesh structure. This results in a high-nickel cathode material that simultaneously exhibits good conductivity and electrolyte resistance. This application uses a wet preparation process to coat the surface of the high-nickel cathode material with a composite coating layer formed by the conductive and coating materials. The process is simple and can effectively improve the specific capacity, cycle performance, and safety performance of the high-nickel cathode material. Compared to high-nickel cathode materials obtained by directly mixing the mixture of conductive and coating materials with the high-nickel cathode material matrix and then heat-treating, this application can form a continuous conductive mesh, significantly improving the conductivity of the cathode material.

[0111] The preparation method of this application is described in detail below with reference to the embodiments:

[0112] Step 100: Mix the mixture containing block copolymer and conductive material with the high-nickel cathode material matrix and perform a first heat treatment to obtain a high-nickel cathode material matrix with conductive material coated on the surface. The surface of the high-nickel cathode material matrix with conductive material coated on the surface has a mesh structure.

[0113] Step 101: Provide block copolymers.

[0114] In some embodiments, the block copolymers of this application include at least one of diblock copolymers, triblock copolymers, and multiblock copolymers. For example, a diblock copolymer may be an AB-type copolymer, and a triblock copolymer may be an ABA-type copolymer, an ABC-type copolymer, etc., wherein A, B, and C all represent monomeric substances. Exemplarily, a diblock copolymer may be at least one of polystyrene-polybutadiene copolymer, polystyrene-polyacrylic acid copolymer, and poly(1,4-butadiene)-polyethylene oxide copolymer; a triblock copolymer may be at least one of styrene-butadiene-3-chloropropylene copolymer, ethylene-ethyl acrylate-glycidyl methacrylate copolymer, and polylactic acid-polyethylene glycol-polylactic acid copolymer; and a multiblock copolymer may be at least one of ether-ether, ether-olefin, and ether-ester copolymer.

[0115] In some embodiments, the block copolymer contains a hydrophilic group at one end and a hydrophobic group at the other end. The end containing the hydrophilic group facilitates the block copolymer's proximity to the conductive material during subsequent reactions, while the presence of the hydrophobic group allows the block copolymer to be uniformly dispersed. Furthermore, high-nickel cathode materials are prone to reacting with water in the air during processing and storage, resulting in the production of a large amount of LiOH on the surface of the high-nickel ternary cathode material. During battery charging, a large amount of gas is released from LiOH, which compromises the battery's safety performance. The block copolymer with hydrophobic groups in this application can reduce the generation of LiOH during the production of high-nickel cathode materials and improve the battery's safety performance.

[0116] For example, the preparation process of the block copolymer of this application is given below using a diblock copolymer as an example:

[0117] Step 1011: After thoroughly mixing the first monomer, the second monomer, the initiator, and the first solvent, proceed with the oil bath reaction.

[0118] In some embodiments, the first monomer includes at least one of N,N-dimethylacrylamide (DMA), styrene, 1,3-butadiene, acrylate, and ethylene oxide.

[0119] In some embodiments, the second monomer includes at least one of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid (DMP), benzyl methacrylate, diethylaminoethyl methacrylate, and isobutyl vinyl ether.

[0120] In some embodiments, the initiator includes at least one of azobisisobutyronitrile (ABIN), acetal / trimethyl iodosilane, acetic acid, and di-tert-butyl peroxide.

[0121] In some embodiments, the first solvent includes at least one of 1,4-dioxane, n-hexane, methanol, and acetone.

[0122] In some embodiments, the mass ratio of the first monomer to the second monomer is 1:(0.001 to 0.1). Specifically, the mass ratio of the first monomer to the second monomer can be, for example, 1:0.001, 1:0.005, 1:0.008, 1:0.01, 1:0.03, 1:0.05, and 1:0.1, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0123] In some embodiments, the mass ratio of the total mass of the first monomer and the second monomer to the mass of the first solvent is 1:(0.5 to 10). Specifically, the mass ratio of the total mass of the first monomer and the second monomer to the mass of the solvent can be, for example, 1:0.5, 1:1, 1:2, 1:3, 1:5, 1:7, 1:9 and 1:10, etc. Of course, other values ​​within the above range are also possible and are not limited here.

[0124] In some embodiments, the oil bath reaction is carried out in an inert gas atmosphere, such as nitrogen.

[0125] In some embodiments, the temperature of the oil bath reaction is 50°C to 90°C. Specifically, the temperature of the oil bath reaction can be, for example, 50°C, 60°C, 70°C, 80°C, and 90°C, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0126] In some embodiments, the oil bath reaction time is 1 hour to 6 hours. Specifically, the oil bath reaction time can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0127] Step 1012: Quench the material obtained in step 1011 and dissolve it in acetone, then precipitate it in cold hexane and filter it to obtain a flocculent solid. Dry the obtained flocculent solid to obtain a block copolymer.

[0128] Of course, other preparation methods in this application can also be used to prepare block copolymers, or commercially available block copolymers can be used directly.

[0129] Step 102: Provide a high-nickel cathode material substrate.

[0130] In some embodiments, the chemical formula of the high-nickel cathode material matrix is: LiNi x Co y Mn z Wherein, 0.8≤x<1, 0<y≤0.12, 0<z≤0.08, and x+y+z=1. The high-nickel cathode material of this application is prepared using conventional methods in the art, and the specific preparation process is not limited in this application.

[0131] Step 103: Mix the mixture containing block copolymer and conductive material with the high-nickel cathode material matrix and then perform a first heat treatment to obtain a high-nickel cathode material matrix with conductive material coated on the surface.

[0132] This application employs a wet process to obtain a mixture of block copolymer and conductive material, which is then mixed with a high-nickel cathode material matrix and subjected to a first heat treatment. This process enables uniform coating on the surface of the high-nickel cathode material matrix, which is beneficial for forming a uniform conductive mesh.

[0133] In some embodiments, the preparation process of the mixture containing block copolymer and conductive material includes: dissolving the block copolymer and conductive material in a second solvent respectively, then adding them sequentially to ethanol and stirring until homogeneous.

[0134] In some embodiments, the second solvent includes at least one of N,N-dimethylformamide, propylamine, dimethylamine, and diethyl ether.

[0135] In some embodiments, the conductive material includes a transition metal oxide, which includes at least one of indium tin oxide, antimony tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, gallium-doped zinc oxide, cuprous aluminate, and tin oxide.

[0136] In some embodiments, the mass ratio of the block copolymer to the conductive material is 1:(0.1 to 10). Specifically, the mass ratio of the block copolymer to the conductive material is 1:0.1, 1:0.5, 1:1, 1:3, 1:5, 1:8, and 1:10, etc., and other values ​​within the above range are also possible and are not limited here. If the mass ratio of the block copolymer to the conductive material is greater than 1:0.1, there is too much block copolymer, and the conductive mesh on the surface of the cathode material is prone to collapse after one heat treatment. If the mass ratio of the block copolymer to the conductive material is less than 1:10, there is less block copolymer, and fewer pores are generated in the cathode material after one heat treatment, which is not conducive to the subsequent filling of the coating material. This application can control the pore size in the cathode material by controlling the amount of block copolymer added, thereby controllably adjusting the morphology of the composite coating material.

[0137] In some embodiments, the mass ratio of the conductive material to the high-nickel cathode material substrate is 1:(100-10000). Specifically, the mass ratio of the conductive material to the high-nickel cathode material substrate can be, for example, 1:100, 1:200, 1:300, 1:400, 1:500, 1:600, 1:700, 1:800, 1:900, and 1:1000, etc., and of course, other values ​​within the above range are also possible and are not limited here. If the mass ratio of the conductive material to the high-nickel cathode material is greater than 1:100, the composite coating layer is too thick, affecting the rate performance of the high-nickel cathode material; if the mass ratio of the conductive material to the high-nickel cathode material substrate on which the conductive material is coated is less than 1:10000, the composite coating layer is too thin, and direct contact between the electrolyte and the high-nickel material cannot be avoided.

[0138] In some embodiments, the concentration of the high-nickel cathode material matrix in ethanol is 0.005 g / ml to 0.5 g / ml. Specifically, the concentration of the high-nickel cathode material matrix in ethanol can be 0.005 g / ml, 0.008 g / ml, 0.01 g / ml, 0.02 g / ml, 0.03 g / ml, 0.04 g / ml, and 0.05 g / ml, etc., and of course, other values ​​within the above range are also possible, and are not limited here.

[0139] In some embodiments, the mixing process is carried out under the first stirring condition.

[0140] In some embodiments, the rotation speed of the first stirring condition is 10 r / min to 100 r / min. For example, the rotation speed of the first stirring condition can be 10 r / min, 20 r / min, 30 r / min, 40 r / min, 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min and 100 r / min, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0141] In some embodiments, the duration of the first stirring condition is 30s to 300s. Specifically, the duration of the first stirring condition can be, for example, 30s, 60s, 100s, 120s, 150s, 180s, 210s, 240s, and 300s, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0142] In some embodiments, the temperature of the first heat treatment is 200°C to 500°C. Specifically, the temperature of the first heat treatment can be, for example, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, and 500°C, etc., and of course, other values ​​within the above range are also possible and are not limited herein. Limiting the temperature of the first heat treatment within the above range allows for high-temperature pyrolysis of the block copolymer, thereby forming pores.

[0143] In some embodiments, the first heat treatment time is 1h to 12h. Specifically, the first heat treatment time can be, for example, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h and 12h, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0144] Step 200: Mix the mixture containing the coating material with the high-nickel cathode material matrix coated with conductive material and then perform a second heat treatment to obtain the high-nickel cathode material.

[0145] Step 201: The mixture containing the coating material is prepared according to the following steps: the coating material and the third solvent are added to the dispersant respectively.

[0146] In some embodiments, the coating material includes at least one selected from carbon-based materials, metal oxides, metal phosphates, metal fluorides, and fast ion conductors. Examples:

[0147] In some embodiments, the carbon-based material includes at least one of activated carbon, graphite, and graphene.

[0148] In some embodiments, the metal oxide includes at least one selected from TiO2, Al2O3, Bi2O3, ZnO, SiO2, and ZrO2;

[0149] In some embodiments, the metal phosphate includes at least one of AlPO4, Co3(PO4)2 and Ni3(PO4)2;

[0150] In some embodiments, the metal fluoride includes at least one of AlF3, YF3, and CuF2;

[0151] In some embodiments, the fast ion conductor includes at least one of Li₂O-2B₂O₃, Li₂TiO₃, and Li₂ZrO₃;

[0152] In some embodiments, the third solvent includes at least one of ethanolamine, ethylenediamine, propylamine, and triethylamine.

[0153] In some embodiments, the dispersant includes at least one of ethanol, acetone, methanol, and ethyl acetate.

[0154] In some embodiments, the volume ratio of the third solvent to the dispersant is 1:(10 to 10000). Specifically, the volume ratio of the second solvent to the dispersant can be 1:10, 1:100, 1:500, 1:1000, 1:5000, and 1:10000, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0155] In some embodiments, the mass ratio of the coating material to the high-nickel cathode material substrate is 1:(100-10000). Specifically, the mass ratio of the coating material to the high-nickel cathode material substrate can be, for example, 1:100, 1:500, 1:1000, 1:5000, and 1:10000, etc., and of course, other values ​​within the above range are also possible, without limitation. If the mass ratio of the coating material to the high-nickel cathode material substrate is greater than 1:100, the composite coating layer is too thick, and the thickness of the coating material exceeds the conductive mesh, resulting in a decrease in the conductivity of the material. If the mass ratio of the coating material to the high-nickel cathode material substrate is less than 1:10000, there is less coating material in the conductive mesh, and the composite coating material has pores, which will lead to direct contact between the high-nickel cathode material substrate and the electrolyte.

[0156] In some embodiments, the mass ratio of the coating material to the conductive material is 1:(0.1 to 10). Specifically, the mass ratio of the coating material to the conductive material can be, for example, 1:0.1, 1:0.3, 1:1, 1:3, 1:5, 1:8, and 1:10. Controlling the mass ratio of the coating material to the conductive material within the above range can ensure that the coating material fills the pores of the high-nickel cathode material matrix with the conductive material coated on the surface, thereby improving the electrochemical stability of the material.

[0157] In some embodiments, dispersion is carried out under a second stirring condition to improve the uniformity of the coating material dispersion.

[0158] In some embodiments, the rotation speed of the second stirring condition is 10 r / min to 100 r / min. For example, the rotation speed of the second stirring condition can be 10 r / min, 20 r / min, 30 r / min, 40 r / min, 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min and 100 r / min, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0159] In some embodiments, the duration of the second stirring condition is 30s to 300s. Specifically, the duration of the second stirring condition can be, for example, 30s, 60s, 100s, 120s, 150s, 180s, 210s, 240s, and 300s, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0160] In some embodiments, the mixing of the mixture containing the coating material and the cathode material is carried out under a third stirring condition;

[0161] In some embodiments, the rotation speed of the third stirring condition is 10 r / min to 100 r / min. For example, the rotation speed of the third stirring condition can be 10 r / min, 20 r / min, 30 r / min, 40 r / min, 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min and 100 r / min, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0162] In some embodiments, the duration of the third stirring condition is 30s to 300s. Specifically, the duration of the third stirring condition can be, for example, 30s, 60s, 100s, 120s, 150s, 180s, 210s, 240s, and 300s, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0163] In some embodiments, the temperature of the second heat treatment is 600°C to 900°C. Specifically, the temperature of the second heat treatment can be, for example, 600°C, 700°C, 800°C, and 900°C, or other values ​​within the above range, which are not limited here.

[0164] In some embodiments, the second heat treatment time is 15h to 30h. Specifically, the second heat treatment time can be, for example, 15h, 18h, 20h, 22h, 25h, 28h and 30h, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0165] In some embodiments, the second heat treatment is carried out in an oxygen atmosphere.

[0166] This application also provides a secondary battery, which includes the above-described positive electrode material or the positive electrode material prepared by the above-described preparation method.

[0167] The present application will be further described below through specific embodiments.

[0168] Example 1

[0169] (1) Dissolve 2.5g of NN dimethacrylamide, 38mg of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid and 1.7mg of azobisisobutyronitrile in 2.5g of 1,4-dioxane. Place the mixture in a 25ml Schlenk polymerization tube and continuously purge with nitrogen for 30min. Then, place it in a 70℃ oil bath and react for 40min. After quenching with liquid nitrogen, dissolve the viscous polymer in 7ml of acetone and precipitate it three times in 500ml of cold hexane. Filter to obtain flocculent solid and finally dry in a vacuum dryer at 70℃ to obtain block polymer.

[0170] (2) Dissolve 16 mg of block polymer and 12 mg of indium tin oxide (ITO) in 1 ml of N,N-dimethylformamide, then add them to 4 ml of ethanol, stir evenly, add 3 g of NCM811 material, stir evenly and let stand until the solvent evaporates, then sinter in a muffle furnace at 400℃ for 1 h to obtain a high nickel cathode material matrix with a grid-like surface coated with conductive material.

[0171] (3) Take 24mg TiO2 and 1μL ethanolamine and add them to 4ml ethanol. After ultrasonication and stirring to disperse completely, add 3g NCM811 material obtained in 2). Stir at 10r / min for 1min, let stand, and after the solvent evaporates, sinter in an oxygen atmosphere in a muffle furnace at 720℃ for 20h to obtain high nickel cathode material.

[0172] The high-nickel cathode material prepared in this embodiment includes an NCM811 core and a composite coating layer covering the surface of the NCM811 core. The composite coating layer includes ITO and TiO2. The ITO has pores, and the TiO2 is embedded in the pores of the ITO. Figure 2 This is a SEM image of the high-nickel cathode material prepared in Example 1. Figure 2 As can be seen, the surface of the NCM811 material in this embodiment is free of cracks and the coating layer is uniform, indicating that ITO and TiO2 were successfully coated on the surface of the NCM811 core.

[0173] Example 2

[0174] (1) Dissolve 2.5g of NN dimethacrylamide, 38mg of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid and 1.7mg of azobisisobutyronitrile in 2.5g of 1,4-dioxane. Place the mixture in a 25ml Schlenk polymerization tube and continuously purge with nitrogen for 30min. Then, place it in a 70℃ oil bath and react for 40min. After quenching with liquid nitrogen, dissolve the viscous polymer in 7ml of acetone and precipitate it three times in 500ml of cold hexane. Filter to obtain flocculent solid and finally dry in a vacuum dryer at 70℃ to obtain block polymer.

[0175] (2) Weigh 12mg of block polymer and 16mg of ITO from step (1) and dissolve them in 1ml of N,N-dimethylformamide. Then add them to 4ml of ethanol and stir until homogeneous. Add 3g of NCM811 material, stir until homogeneous, and let stand until the solvent evaporates. Then place it in a muffle furnace at 400℃ for sintering for 1h to obtain a high-nickel cathode material matrix with a grid-like surface coated with conductive material.

[0176] (3) Take 18mg TiO2 and 1μL ethanolamine and add them to 4ml ethanol. After ultrasonication and stirring to disperse completely, add 3g NCM811 material obtained in 2). Stir at 10r / min for 1min, let stand, and after the solvent evaporates, sinter in an oxygen atmosphere in a muffle furnace at 720℃ for 20h to obtain high nickel cathode material.

[0177] Example 3

[0178] Unlike Example 1, in step (2), 22 mg of block polymer and 6 mg of ITO were weighed, and in step (3), 30 mg of TiO2 was weighed.

[0179] Example 4

[0180] Unlike Example 1, in step (2), 2 mg of block polymer and 30 mg of ITO were weighed, and in step (3), 3 mg of TiO2 was weighed.

[0181] Example 5

[0182] Unlike Example 1, in step (2), 1 mg of block polymer and 32 mg of ITO were weighed, and in step (3), 0.3 mg of TiO2 was weighed.

[0183] Example 6

[0184] Unlike Example 1, in step (2), 12 mg of block polymer and 16 mg of ITO were weighed, and in step (3), 40 mg of TiO2 was weighed.

[0185] Example 7

[0186] Unlike Example 1, in step (2), 12 mg of block polymer and 16 mg of ITO were weighed, and in step (3), 0.1 mg of TiO2 was weighed.

[0187] Example 8

[0188] Unlike Example 1, in step (2), 36 mg of block polymer and 48 mg of ITO were weighed, and in step (3), 54 mg of TiO2 were weighed.

[0189] Example 9

[0190] Unlike Example 1, step (1) is omitted, and the styrene-butadiene-3-chloropropylene copolymer triblock polymer is directly used in the reaction of step (2).

[0191] Example 10

[0192] Unlike Example 1, in step (2), ITO is replaced with antimony tin oxide (ATO).

[0193] Example 11

[0194] Unlike Example 1, TiO2 is replaced with graphite in step (3).

[0195] Comparative Example 1

[0196] 24 mg TiO2 and 1 μL ethanolamine were added to 4 ml ethanol. After ultrasonication and stirring to disperse completely, 3 g of untreated NCM811 material was added. The mixture was stirred at 10 r / min for 1 min, allowed to stand, and after the solvent evaporated, it was sintered in an oxygen atmosphere in a muffle furnace at 720 °C for 20 h to obtain a high-nickel cathode material.

[0197] Comparative Example 2

[0198] Take 24 mg TiO2, 16 mg ITO and 1.5 μL ethanolamine and add them to 4 ml ethanol. After ultrasonication and stirring to disperse completely, add 3 g of untreated NCM811 material, stir at 10 r / min for 1 min, let stand, and after the solvent evaporates, sinter in an oxygen atmosphere in a muffle furnace at 720℃ for 20 h to obtain high nickel cathode material.

[0199] Performance testing

[0200] (1) SEM was used to measure the coating of high-nickel cathode material.

[0201] (2) The specific surface area of ​​the high-nickel cathode material was measured using a McSurface Surface Gauge.

[0202] (3) The conductivity of the high-nickel cathode material was tested using a conductivity meter.

[0203] (4) Discharge performance test at different rates. Test conditions: voltage 3.0V~4.3V, 0.1C charge / 0.1C discharge, 0.5C charge / 0.5C discharge, 0.5C charge / 1.0C discharge, 0.5C charge / 2.0C discharge, 0.5C charge

[0204] Discharge at 5.0C.

[0205] (5) Electrochemical performance testing:

[0206] Button cell fabrication: The NCM811 materials of Examples 1 to 11 and Comparative Examples 1 and 2 were mixed with conductive agent and polyvinylidene fluoride in an N-methylpyrrolidone solution at a mass ratio of 96:2:2 and coated evenly onto an aluminum foil current collector. The mixture was then vacuum dried at 100°C to obtain an electrode sheet. The electrode sheet was then assembled into a button cell in a glove box for testing. The counter electrode was made of lithium metal, the separator was Celgard C2400, and the electrolyte was a 1.3M LiPF6 solution of EC, PC, and DEC (volume ratio 3:1:6).

[0207] The test results are shown in Tables 1 and 2.

[0208] Table 1. Test results of performance parameters of high-nickel cathode materials in each embodiment and comparative example.

[0209]

[0210]

[0211] Table 2. Rate performance test results of high-nickel cathode materials in each embodiment and comparative example

[0212]

[0213] As shown in Table 1, in the composite coating layer of the high-nickel cathode materials prepared in Examples 1-11 of this application, the porous conductive substrate can form a conductive grid, and the coating material is embedded in the conductive grid. On the one hand, the conductive substrate and the coating material are distributed in the same coating layer, which can improve the conductivity of the cathode material and block the direct contact between the cathode material and the electrolyte; on the other hand, the coating material filling the conductive grid can form a stable electrochemical interface. The high-nickel cathode material of this application can take into account both the stability of the electrochemical interface and the conductivity, thereby improving the energy density, cycle performance and safety performance of the high-nickel cathode material.

[0214] Figure 3 These are comparative test images of the button cells from Embodiments 1 and 2 of the present invention and Comparative Examples 1 and 2. From... Figure 3It can be seen that the charge-discharge curve and capacity of Example 2 are slightly improved compared with Comparative Example 1, and the charge-discharge curve and capacity performance of Example 1 and Example 2 are significantly improved compared with Comparative Example 1 and Comparative Example 2.

[0215] In Example 6, by excessively increasing the amount of coating material, the coating layer thickness is higher than the conductive mesh thickness, which reduces the synergistic effect between the conductive mesh and the coating material, resulting in poor coin-holding performance of the high-nickel cathode material.

[0216] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A high-nickel cathode material, characterized in that, The high-nickel cathode material includes a high-nickel cathode material matrix and a composite coating layer covering at least a portion of the surface of the high-nickel cathode material matrix. The composite coating layer includes a conductive matrix with pores, and the coating material is dispersed within the pores. The conductive substrate is made of at least one of indium tin oxide, antimony tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, gallium-doped zinc oxide, and tin oxide; the coating material is made of at least one of metal oxide and fast ion conductor. The thickness of the composite coating layer is 10nm to 50nm, and the thickness of the composite coating layer is equal to the thickness of the conductive substrate; The preparation method of the high-nickel cathode material includes the following steps: A mixture containing block copolymers and conductive materials is mixed with a high-nickel cathode material matrix and then subjected to a first heat treatment to obtain a high-nickel cathode material matrix with a conductive material coating on its surface. The surface of the high-nickel cathode material matrix with the conductive material coating has a grid-like structure. The block copolymer contains a hydrophilic group at one end and a hydrophobic group at the other end. The mixture containing the coating material is mixed with the high-nickel cathode material matrix coated with the conductive material, and then subjected to a second heat treatment to obtain the high-nickel cathode material; the mass ratio of the coating material to the conductive material is 1:(0.1~10), and the mass ratio of the coating material to the high-nickel cathode material matrix is ​​1:(100~10000); the coating material is dispersed in the conductive matrix with a mesh structure, and the conductivity of the conductive matrix is ​​greater than the conductivity of the coating material.

2. The high-nickel cathode material according to claim 1, characterized in that, The high-nickel cathode material includes at least one of the following features (1) to (3): (1) The metal oxide includes at least one of TiO2, Al2O3, Bi2O3, ZnO, SiO2 and ZrO2; (2) The fast ion conductor includes at least one of Li2O-2B2O3, Li2TiO3 and Li2ZrO3; (3) The average pore size of the hole is 10nm~200nm.

3. The high-nickel cathode material according to claim 1, characterized in that, The general chemical formula of the high-nickel cathode material is shown in formula (Ⅰ): LiNi x Co y Mr z @A / B (Ⅰ) In equation (Ⅰ), 0.8 ≤ x < 1, 0 < y ≤ 0.12, 0 < z ≤ 0.08, and x + y + z = 1, the LiNi x Co y Mn z The chemical formula of the high-nickel cathode material matrix is ​​given, wherein A / B is distributed in the LiNi... x Co y Mn z The surface of A includes a transition metal oxide, and B includes at least one of a metal oxide and a fast ion conductor.

4. The high-nickel cathode material according to claim 1, characterized in that, The high-nickel cathode material includes at least one of the following features (1) to (2): (1) The specific surface area of ​​the high-nickel cathode material is 0.3 m². 2 / g~ 3m 2 / g; (2) The conductivity of the high-nickel cathode material is 10. -1 S / cm~10 2 S / cm.

5. The high-nickel cathode material according to claim 1, characterized in that, The preparation method includes at least one of the following features (1) to (13): (1) The block copolymer includes at least one of diblock copolymers and multiblock copolymers; (2) The block copolymer comprises a diblock polymer, which is prepared by the following steps: The first monomer, the second monomer, the initiator and the first solvent are mixed evenly, and the mixture is subjected to an oil bath reaction. (3) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the first monomer includes at least one of N,N dimethylacrylamide, styrene, 1,3-butadiene, acrylate and ethylene oxide; (4) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the second monomer includes at least one of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid, benzyl methacrylate, diethylaminoethyl methacrylate and isobutyl vinyl ether; (5) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the initiator includes at least one of azobisisobutyronitrile (AIBN), acetal / trimethyl iodosilane, acetic acid and di-tert-butyl peroxide; (6) The block copolymer includes a diblock polymer, which is prepared by the following steps: mixing a first monomer, a second monomer, an initiator and a first solvent evenly, and subjecting the mixture to an oil bath reaction, wherein the first solvent includes at least one of 1,4-dioxane, n-hexane, methanol and acetone; (7) The block copolymer comprises a diblock polymer, which is prepared by the following steps: The first monomer, the second monomer, the initiator and the first solvent are mixed evenly, and the mixture is subjected to an oil bath reaction. The mass ratio of the first monomer to the second monomer is 1:(0.001~0.1). (8) The block copolymer comprises a diblock polymer, which is prepared by the following steps: The first monomer, the second monomer, the initiator and the first solvent are mixed evenly, and the mixture is subjected to an oil bath reaction. The mass ratio of the total mass of the first monomer and the second monomer to the mass of the first solvent is 1:(0.5~10). (9) The block copolymer comprises a diblock polymer, which is prepared by the following steps: The first monomer, the second monomer, the initiator and the first solvent are mixed evenly, and the mixture is subjected to an oil bath reaction at a temperature of 50°C to 90°C. (10) The block copolymer comprises a diblock polymer, which is prepared by the following steps: The first monomer, the second monomer, the initiator and the first solvent are mixed evenly, and the mixture is subjected to an oil bath reaction for 1 h to 6 h. (11) The block copolymer comprises a diblock polymer, which is prepared by the following steps: The first monomer, the second monomer, the initiator and the first solvent are mixed evenly, and the mixture is subjected to an oil bath reaction in an inert gas atmosphere. (12) The block copolymer comprises a diblock polymer, which is prepared by the following steps: The first monomer, the second monomer, the initiator and the first solvent are mixed evenly, and the mixture is subjected to an oil bath reaction. Finally, the mixture is quenched, dissolved, precipitated, filtered and dried. (13) The block copolymer comprises a diblock polymer, which is prepared by the following steps: The first monomer, the second monomer, the initiator and the first solvent are mixed evenly, and the mixture is subjected to an oil bath reaction. Finally, the mixture is quenched, dissolved, precipitated, filtered and dried. The solvent for dissolution includes acetone.

6. The high-nickel cathode material according to claim 1, characterized in that, The preparation method includes at least one of the following features (1) to (11): (1) The conductive material includes a transition metal oxide, which includes at least one of indium tin oxide, antimony tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, gallium-doped zinc oxide, and tin oxide; (2) The mass ratio of the block copolymer to the conductive material is 1:(0.1~10); (3) The mixture containing block copolymer and conductive material further includes a second solvent; (4) The mixture containing block copolymer and conductive material further includes a second solvent, the second solvent including at least one of N,N-dimethylformamide, propylamine, dimethylamine and diethyl ether; (5) The chemical formula of the high-nickel cathode material matrix is: LiNi x Co y Mn z Where 0.8≤x<1, 0<y≤0.12, 0<z≤0.08, and x+y+z=1; (6) The mass ratio of the conductive material to the high-nickel cathode material matrix is ​​1:(100~10000). (7) The mixing is carried out under the first stirring condition; (8) The mixing is carried out under the first stirring condition, wherein the stirring speed is 10 r / min to 100 r / min; (9) The mixing is carried out under the first stirring condition, and the time of the first stirring condition is 30s~300s; (10) The temperature of the first heat treatment is 200℃~500℃; (11) The first heat treatment time is 1h~12h.

7. The high-nickel cathode material according to claim 1, characterized in that, The mixture containing the coating material is prepared according to the following steps: the coating material and the third solvent are added to the dispersant respectively, and the preparation method includes at least one of the following features (1) to (5): (1) The coating material includes at least one of metal oxide and fast ion conductor, wherein the metal oxide includes at least one of TiO2, Al2O3, Bi2O3, ZnO, SiO2 and ZrO2; (2) The fast ion conductor includes at least one of Li2O-2B2O3, Li2TiO3 and Li2ZrO3; (3) The third solvent includes at least one of ethanolamine, ethylenediamine, propylamine and triethylamine; (4) The dispersant includes at least one of ethanol, acetone, methanol and ethyl acetate; (5) The volume ratio of the third solvent to the dispersant is 1: (10~10000).

8. The high-nickel cathode material according to claim 1, characterized in that, The preparation method includes at least one of the following features (1) to (6): (1) The mixing of the mixture containing the coating material and the high-nickel cathode material matrix with the surface coated conductive material is carried out under the third stirring condition; (2) The mixing of the mixture containing the coating material and the high-nickel cathode material matrix with the surface coated conductive material is carried out under the third stirring condition; the stirring speed of the third stirring condition is 10 r / min to 100 r / min; (3) The mixing of the mixture containing the coating material and the high-nickel cathode material matrix with the surface coated conductive material is carried out under the third stirring condition; the time of the third stirring condition is 30s~300s; (4) The temperature of the second heat treatment is 600℃~900℃; (5) The second heat treatment time is 15h~30h; (6) The second heat treatment is carried out in an oxygen atmosphere.

9. A secondary battery, characterized in that, The secondary battery comprises the high-nickel cathode material as described in any one of claims 1 to 8.

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