Nickel-based positive electrode material and preparation method therefor, lithium-ion battery and electric device

Abstract

Disclosed in the present application is a nickel-based positive electrode material, which comprises a nickel-based positive electrode material matrix and a solid electrolyte coating layer coating the surface of the nickel-based positive electrode material matrix. A preparation method for the nickel-based positive electrode material comprises: uniformly mixing a positive electrode material precursor, a lithium source and a dopant containing a doping element M, and then sintering the mixture, so as to obtain a sintered product; washing the sintered product with water, and drying same to obtain a washed product; and uniformly mixing the washed product with an antimony source and a fluorine source, and then sintering the mixture, so as to obtain a nickel-based positive electrode material. Further disclosed in the present application are a lithium-ion battery and an electric device. In the present application, the solid electrolyte coating layer is used as a solid electrolyte membrane of the positive electrode material matrix, has a high conductivity and good stability, and can also reduce the surface stress of the material, reduce the specific surface area of the material, protect the surface of the material, reduce side reactions with the electrolyte solution during the cycling process of the material, and improve the cycling stability of the material.

Description

Nickel-based positive electrode material, preparation method thereof, lithium ion battery and electric device

[0001] Cross-reference to related applications

[0002] This application claims priority from Chinese Patent Application No. 202411132681.7, filed on August 19, 2024, entitled "Nickel-based positive electrode material, preparation method thereof, lithium ion battery and electric device", which is incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present application belongs to the field of lithium ion batteries, and particularly relates to a nickel-based positive electrode material, a preparation method thereof, a lithium ion battery and an electric device. BACKGROUND

[0004] In recent years, with the development of the new energy industry, higher requirements have been put forward for the energy density and cycle life of lithium ion batteries. High-nickel ternary positive electrode materials have attracted much attention due to their high energy density and relatively low manufacturing cost. However, with the increase of nickel content, there are many unstable residual lithium compounds on the surface of high-nickel layered oxides, which have a great impact on the performance of the material.

[0005] Currently, the production of traditional high-nickel ternary positive electrode materials has added a water washing process technology, which removes the residual lithium compounds through water washing before multiple sintering. However, because high-nickel ternary materials are sensitive to moisture, excessive water washing will cause lithium to precipitate on the surface of the material matrix, destroy the surface structure of the material, and worsen the capacity, rate and long-term cycle performance. At present, there are modification methods such as dry sintering and coating to prepare an oxide coating layer for modification, but the coating state and modification effect are still not good enough, and problems such as high residual lithium, surface side reactions and rapid impedance growth still exist, which affect the electrochemical performance of high-nickel nickel-based positive electrode materials. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the deficiencies and defects mentioned in the above background art, and to provide a nickel-based positive electrode material, a preparation method thereof, a lithium ion battery and an electric device.

[0007] To solve the above technical problems, the technical solution proposed by the present application is as follows:

[0008] The first aspect of the present application provides a nickel-based positive electrode material, which comprises a nickel-based positive electrode material matrix and a solid-state electrolyte coating layer coated on the surface of the nickel-based positive electrode material matrix, and the solid-state electrolyte coating layer contains lithium, antimony, fluorine, carbon and oxygen elements.

[0009] The nickel-based positive electrode material described above, optionally, the surface of the primary particles of the nickel-based positive electrode material is also wrapped with a solid-state electrolyte coating layer.

[0010] The nickel-based positive electrode material has a chemical formula of Li z Ni 1-x-y-u Co x Me y M u O 2-v , wherein 0.9≤z≤1.1, 0≤x≤0.2, 0≤y≤0.2, 0

[0011] , wherein z can be 0.9, 0.92, 0.95, 0.98, 1.0, 1.02, 1.05, 1.08, 1.1, and any value within the range formed by any two of the above values; x and y can each independently be 0, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, and any value within the range formed by any two of the above values; and u and v can each independently be 0.001, 0.002, 0.003, 0.004, 0.005, and any value within the range formed by any two of the above values.

[0012] The nickel-based positive electrode material has a chemical formula of Li

[0013] The nickel-based positive electrode material has a chemical formula of Li

[0014] The nickel-based positive electrode material has a chemical formula of Li 2 , a particle size of primary particles of the nickel-based positive electrode material is 140-250 nm, and residual lithium of the nickel-based positive electrode material is 500-2000 ppm.

[0015] The second aspect of the present application provides a preparation method of the nickel-based positive electrode material.

[0016] (1) mixing a positive electrode material precursor, a lithium source, and a dopant containing a doping element M uniformly, and then performing sintering treatment to obtain a sintered product;

[0017] (2) performing water washing and drying on the sintered product obtained in step (1) to obtain a water-washed product;

[0018] (3) mixing the water washing product obtained in step (2) with a source of antimony and a source of fluorine to obtain a mixture, and then sintering the mixture to obtain the nickel-based positive electrode material.

[0019] In the preparation method, in step (3), the sintering treatment is performed in an oxygen atmosphere, and includes three-stage sintering, i.e., first-stage sintering at a temperature of 100-300°C for 1-5h, second-stage sintering at a temperature of 300-500°C for 2-12h, and third-stage sintering at a temperature of 500-700°C for 4-15h. Further preferably, the first-stage sintering temperature is 150-250°C, the second-stage sintering temperature is 350-450°C, and the third-stage sintering temperature is 600-700°C.

[0020] In the preparation method, in step (3), the amount of the source of antimony is 1000-4000ppm of antimony element based on the mass of the water washing product, and the amount of the source of fluorine is 500-2000ppm of fluorine element based on the mass of the water washing product.

[0021] In the preparation method, in step (1), the sintering treatment is performed in an oxygen atmosphere, and includes two-stage sintering, i.e., first-stage sintering at a temperature of 400-600°C for 2-5h, and second-stage sintering at a temperature of 600-800°C for 8-20h. Further preferably, the first-stage sintering temperature is 450-550°C, and the second-stage sintering temperature is 700-800°C.

[0022] In the preparation method, the source of lithium is one or more of lithium hydroxide, lithium carbonate or lithium nitrate.

[0023] The dopant containing the doping element M is selected from one or more of oxides, hydroxides, nitrates, phosphates or sulfates containing the doping element M.

[0024] The source of antimony is one or more of antimony trioxide, antimony pentoxide, antimony trisulfide or antimony trifluoride.

[0025] The source of fluorine includes one or more of lithium fluoride, polyvinylidene fluoride, polytrifluorochloroethylene or polytetrafluoroethylene. When the source of fluorine is lithium fluoride, the lithium carbonate on the surface of the matrix material acts as a carbon source to react with the source of fluorine and the source of antimony to form a solid-state electrolyte coating layer containing lithium, antimony, fluorine, carbon and oxygen.

[0026] Further preferably, when the source of fluorine includes one or more of polyvinylidene fluoride, polytrifluorochloroethylene or polytetrafluoroethylene, the source of fluorine also acts as a carbon source, and the amount of carbon in the carbon source is 300-1200ppm based on the mass of the water washing product.

[0027] Optionally, in step (2), the temperature of the water washing is 5-25°C, the solid-liquid mass ratio in the water washing process is 0.8-1.5, and the stirring speed in the water washing process is 400-900 rpm.

[0028] The third aspect of the present application provides a lithium ion battery comprising the nickel-based positive electrode material or the nickel-based positive electrode material prepared by the preparation method.

[0029] The fourth aspect of the present application provides an electric device comprising the lithium ion battery.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] (1) The nickel-based positive electrode material of the present application is wrapped with a solid-state electrolyte coating layer on the surface of the material substrate, the coating layer acts as a solid-state electrolyte film of the positive electrode material substrate, has high electrical conductivity and good stability, can reduce the surface stress of the material, reduce the specific surface area of the material, protect the surface of the material, reduce the side reaction of the material with the electrolyte during the material cycle process, and improve the cycle stability of the material; at the same time, the coating layer can also fix the oxygen atoms on the surface of the material while establishing a lithium ion transmission channel, inhibit the generation of nickel oxide phase in the side reaction of the high-nickel component on the surface of the high-nickel positive electrode material during the cycle process, and greatly improve the cycle stability of the material.

[0032] (2) The nickel-based positive electrode material of the present application is wrapped with a solid-state electrolyte coating layer on the surface of the material substrate, the coating layer is a composite coating layer of LiSbO3, LiSbF6 and Li2CO3, LiSbO3 and LiSbF6 are ion conductors, which can reduce the impedance of the material, LiSbF6 can inhibit the precipitation of lattice oxygen, stabilize the surface structure of the material, improve the lithium ion diffusion rate, and form an inorganic solid-state electrolyte film of the material together with LiSbO3 and surface Li2CO3, which has the characteristics of low impedance, high electrical conductivity and high stability.

[0033] (3) The preparation method of the present application combines the characteristics of the coating material, adopts a multi-stage sintering dry coating process, wherein the first stage sintering is the melting of the organic fluorine source, the second stage sintering is the melting of the antimony source, and the third stage sintering is the melting of the antimony source and the carbonization of the organic fluorine source. In the sintering process, the surface residual lithium is significantly reduced by reacting with the surface residual lithium, and the reaction with the substrate is more uniform and sufficient while generating lithium ion conductors. The preparation method of the multi-stage sintering is simple, and the mutual action of the organic fluorine source and the antimony source can play a good melting effect, which can significantly reduce the sintering temperature and save energy. Through the reaction in the molten state, a uniform and thin solid-state electrolyte film coating layer is formed on the surface of the primary particles and the secondary particles, which can significantly improve the electrochemical performance of the positive electrode material at high temperature and high voltage. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is an SEM image of a nickel-based positive electrode material prepared in Example 1 of the present application.

[0035] Figure 2 is a section view of the nickel-based positive electrode material prepared in Example 1 of the present application.

[0036] Figure 3 is a section EPMA image of the nickel-based positive electrode material prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0037] For the purpose of facilitating the understanding of the present application, the present application will be described in greater detail below in conjunction with the accompanying drawings and preferred embodiments, but the scope of protection of the present application is not limited to the following specific embodiments.

[0038] Unless otherwise defined, all the professional terms used herein have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing the specific embodiments and are not intended to limit the scope of protection of the present application.

[0039] Unless otherwise specified, the various raw materials, reagents, instruments and equipment, etc. used in the present application can be purchased on the market or can be prepared by existing methods.

[0040] Example 1

[0041] A nickel-based positive electrode material of the present application includes a nickel-based positive electrode material substrate and a solid electrolyte coating layer wrapped on the surface of the nickel-based positive electrode material substrate, and the surface of the primary particles of the nickel-based positive electrode material is also wrapped with a solid electrolyte coating layer. The chemical general formula of the nickel-based positive electrode material substrate is Li 1.01 Ni 0.929 Co 0.03 Mn 0.04 Zr 0.001 O2, the solid electrolyte coating layer is a composite coating layer of LiSbO3, LiSbF6 and Li2CO3 with a molar ratio of 3:3.7:25.9, the mass of the solid electrolyte coating layer is 0.86wt% of the mass of the nickel-based positive electrode material substrate, the specific surface area of the nickel-based positive electrode material is 0.64m 2 / g, the particle size of the primary particles thereof is 190nm, and the residual lithium thereof is 1114ppm.

[0042] The nickel-based positive electrode material in the present embodiment has a preparation method including the following steps:

[0043] (1) A nickel-cobalt-manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04(OH)2, lithium hydroxide monohydrate, zirconium dioxide are added into a high-speed mixing blender in a ratio of 1:1.05:0.001 by mole, stirred at a speed of 1800 r / min for 30 min, then heated to 500 DEG C at a heating rate of 3 DEG C / min in a box furnace with an oxygen concentration of >96%, and kept for 2 h, then heated to 740 DEG C and kept for 12 h, naturally cooled to room temperature, crushed, and sieved through a 300-mesh sieve to obtain a primary sintered material.

[0044] (2) The primary sintered material obtained in step (1) is washed with deionized water for 3 min, the solid-liquid mass ratio of the washing is 1.0, the temperature of the deionized water for washing is controlled at 8 DEG C, the stirring rate is 700 rpm / min, after washing, the sample is placed in a vacuum oven and vacuum dried at 160 DEG C for 6 h, then naturally cooled to room temperature, and sieved through a 300-mesh sieve to obtain a water-washed matrix Li 1.01 Ni 0.929 Co 0.03 Mn 0.04 Zr 0.001 O2.

[0045] (3) The water-washed matrix, antimony pentoxide, and polyvinylidene fluoride are added into a high-speed mixing blender in a ratio of 1:0.0027:0.0017 by mass, stirred at a speed of 1800 r / min for 30 min, then heated to 200 DEG C at a heating rate of 3 DEG C / min in a box furnace under an oxygen atmosphere, kept for 2 h, then heated to 400 DEG C and kept for 4 h, finally heated to 600 DEG C and kept for 8 h, naturally cooled to room temperature to obtain a sintered material, the sintered material is sieved through a 300-mesh sieve to obtain the nickel-based positive electrode material of the present embodiment.

[0046] The SEM image of the nickel-based positive electrode material prepared in the present embodiment is shown in FIG. 1, from which it can be seen that there are traces of a coating layer on the surface of the material. The cross-sectional view and the EPMA image of the cross section of the nickel-based positive electrode material prepared in the present embodiment are shown in FIGS. 2 and 3, respectively, from which it can be seen from the EPMA element distribution map that a thin coating layer containing antimony, fluorine, and carbon elements is formed on the surface of the material, and it can be found from the comparison of the cross-sectional views that the surface of the primary particles of the material also contains antimony, fluorine, and carbon coating elements, i.e., a solid electrolyte coating layer is formed on the surface of the primary particles inside the matrix, and a solid electrolyte coating layer is also formed on the surface of the matrix.

[0047] Example 2:

[0048] A nickel-based positive electrode material of the present application comprises a nickel-based positive electrode material matrix and a solid electrolyte coating layer wrapped on the surface of the nickel-based positive electrode material matrix, and the surface of the primary particles of the nickel-based positive electrode material also has a solid electrolyte coating layer, the chemical general formula of the nickel-based positive electrode material matrix is Li 1.01 Ni 0.929 Co0.03 Mn 0.04 Zr 0.001 O2, the solid electrolyte coating layer is a composite coating layer of LiSbO3, LiSbF6 and Li2CO3 in a molar ratio of 1.5:2.8:19.0, the mass of the solid electrolyte coating layer is 1.15wt% of the mass of the nickel-based positive electrode material substrate, the specific surface area of the nickel-based positive electrode material is 0.58m 2 / g, the particle size of the primary particles thereof is 190nm, and the residual lithium thereof is 1416ppm.

[0049] The nickel-based positive electrode material in the embodiment has a preparation method including the following steps:

[0050] (1) adding nickel-cobalt-manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2, lithium hydroxide monohydrate and zirconium dioxide into a high-speed mixing stirrer in a molar ratio of 1:1.05:0.001, stirring at a speed of 1800r / min for 30min, then heating to 500℃ at a heating rate of 3℃ / min in a box furnace with an oxygen concentration of ≥96%, and then heating to 740℃ for 12h, and then naturally cooling to room temperature, crushing, and then passing through a 300-mesh sieve to obtain a primary sintered material.

[0051] (2) washing the primary sintered material obtained in step (1) with deionized water for 3min, the solid-liquid mass ratio of the washing being 1.0, the temperature of the deionized water being controlled at 8℃, and the stirring rate being 700rpm / min, and then placing the sample in a vacuum oven for vacuum drying at 160℃ for 6h, and then naturally cooling to room temperature, and then passing through a 300-mesh sieve to obtain a washed substrate Li 1.01 Ni 0.929 Co 0.03 Mn 0.04 Zr 0.001 O2.

[0052] (3) adding the washed substrate, antimony trioxide and polyvinylidene fluoride into a high-speed mixing stirrer in a mass ratio of 1:0.0030:0.0025, stirring at a speed of 1800r / min for 30min, and then heating to 250℃ at a heating rate of 3℃ / min in a box furnace under an oxygen atmosphere, and then heating to 400℃ for 4h, and then heating to 660℃ for 8h, and then naturally cooling to room temperature to obtain a sintered material, and then sieving the sintered material using a 300-mesh sieve to obtain the nickel-based positive electrode material of the embodiment.

[0053] Example 3:

[0054] The nickel-based positive electrode material comprises a nickel-based positive electrode material substrate and a solid electrolyte coating layer wrapped on the surface of the nickel-based positive electrode material substrate, and the surface of primary particles of the nickel-based positive electrode material is also wrapped with the solid electrolyte coating layer. The chemical general formula of the nickel-based positive electrode material substrate is Li 1.01 Ni 0.929 Co 0.03 Mn 0.04 Zr 0.001 O2. The solid electrolyte coating layer is a composite coating layer of LiSbO3, LiSbF6 and Li2CO3 with a molar ratio of 3:3.5:3.9. The mass of the solid electrolyte coating layer is 0.44wt% of the mass of the nickel-based positive electrode material substrate. The specific surface area of the nickel-based positive electrode material is 0.72m 2 / g. The particle size of the primary particles of the nickel-based positive electrode material is 190nm. The residual lithium is 865ppm.

[0055] The nickel-based positive electrode material in the embodiment has a preparation method comprising the following steps:

[0056] (1) A nickel-cobalt-manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2, lithium hydroxide monohydrate and zirconium dioxide are added into a high-speed mixing stirrer in a molar ratio of 1:1.05:0.001. The mixture is stirred at a speed of 1800r / min for 30min. Then, the mixture is heated to 500℃ at a heating rate of 3℃ / min in a box furnace with an oxygen concentration of ≥96%, and then heated to 740℃ for 12h. The mixture is naturally cooled to room temperature, crushed, and sieved through a 300 mesh sieve to obtain a primary sintered material.

[0057] (2) The primary sintered material obtained in step (1) is washed with deionized water for 3min. The solid-liquid mass ratio of the washing is 1.0. The temperature of the deionized water for washing is controlled at 8℃. The stirring rate is 700rpm / min. After washing, the sample is placed in a vacuum oven and dried at 160℃ for 6h. Then, the sample is naturally cooled to room temperature, sieved through a 300 mesh sieve, and a washed substrate Li 1.01 Ni 0.929 Co 0.03 Mn 0.04 Zr 0.001 O2 is obtained.

[0058] (3) the water-washed substrate, antimony pentoxide and lithium fluoride are added into a high-speed mixing stirrer at a mass ratio of 1:0.0027:0.0014, stirred at a speed of 1800 r / min for 30 min, then heated to 200°C at a heating rate of 3°C / min in a box furnace under an oxygen atmosphere, kept at 200°C for 2 h, then heated to 400°C at a heating rate of 3°C / min, kept at 400°C for 4 h, finally heated to 600°C at a heating rate of 3°C / min, kept at 600°C for 8 h, and naturally cooled to room temperature to obtain a sintered material, and the sintered material is sieved using a 300-mesh sieve to obtain the nickel-based positive electrode material of the example.

[0059] Example 4:

[0060] The nickel-based positive electrode material of the example is prepared by the following method:

[0061] (1) the nickel-cobalt-manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2, lithium hydroxide monohydrate and zirconium dioxide are added into a high-speed mixing stirrer at a molar ratio of 1:1.05:0.001, stirred at a speed of 1800 r / min for 30 min, then heated to 500°C at a heating rate of 3°C / min in a box furnace with an oxygen concentration of ≥96%, kept at 500°C for 2 h, then heated to 740°C at a heating rate of 3°C / min, kept at 740°C for 12 h, naturally cooled to room temperature, crushed, and sieved through a 300-mesh sieve to obtain a primary sintered material.

[0062] (2) the primary sintered material is washed with deionized water for 3 min, the solid-liquid mass ratio of the washing is 1.0, the temperature of the deionized water is controlled at 8°C, and the stirring rate is 700 rpm / min, then the sample is placed in a vacuum oven and vacuum dried at 160°C for 6 h, then naturally cooled to room temperature, sieved through a 300-mesh sieve, and a water-washed substrate material Li 1.01 Ni 0.929 Co 0.03 Mn 0.04 Zr 0.001 O2.

[0063] (3) the water-washed substrate, antimony pentoxide and polyvinylidene fluoride are added into a high-speed mixing stirrer at a mass ratio of 1:0.0027:0.005, stirred at a speed of 1800 r / min for 30 min, then heated to 200°C at a heating rate of 3°C / min in a box furnace under an oxygen atmosphere, kept at 200°C for 2 h, then heated to 400°C at a heating rate of 3°C / min, kept at 400°C for 4 h, finally heated to 600°C at a heating rate of 3°C / min, kept at 600°C for 8 h, and naturally cooled to room temperature to obtain a sintered material, and the sintered material is sieved using a 300-mesh sieve to obtain the nickel-based positive electrode material.

[0064] Example 5:

[0065] The nickel-based positive electrode material of the embodiment, a preparation method thereof comprises the following steps:

[0066] (1) A nickel-cobalt-manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2, lithium hydroxide monohydrate, and zirconium dioxide are added into a high-speed mixing stirrer in a molar ratio of 1:1.05:0.001, stirred at a speed of 1800 r / min for 30 min, then heated to 500 ℃ at a heating rate of 3 ℃ / min in a box furnace with an oxygen concentration of ≥96%, and kept for 2 h, then heated to 740 ℃ and kept for 12 h, naturally cooled to room temperature, crushed, and sieved through a 300-mesh sieve to obtain a primary sintered material.

[0067] (2) The primary sintered material is washed with deionized water for 3 min, the solid-liquid mass ratio of the washing is 1.0, the temperature of the deionized water is controlled at 8 ℃, the stirring rate is 700 rpm / min, after washing, the sample is placed in a vacuum oven and vacuum dried at 160 ℃ for 6 h, then naturally cooled to room temperature, and sieved through a 300-mesh sieve to obtain a water-washed base material Li 1.01 Ni 0.929 Co 0.03 Mn 0.04 Zr 0.001 O2.

[0068] (3) The water-washed base material, antimony pentoxide, and polyvinylidene fluoride are added into a high-speed mixing stirrer in a mass ratio of 1:0.0027:0.0017, stirred at a speed of 1800 r / min for 30 min, then heated to 600 ℃ at a heating rate of 3 ℃ / min in a box furnace under an oxygen atmosphere, kept for 8 h, naturally cooled to room temperature to obtain a sintered material, the sintered material is sieved through a 300-mesh sieve to obtain a nickel-based positive electrode material.

[0069] Comparative Example 1:

[0070] The nickel-based positive electrode material of the comparative embodiment, a preparation method thereof comprises the following steps:

[0071] (1) A nickel-cobalt-manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2, lithium hydroxide monohydrate, and zirconium dioxide are added into a high-speed mixing stirrer in a molar ratio of 1:1.05:0.001, stirred at a speed of 1800 r / min for 30 min, then heated to 500 ℃ at a heating rate of 3 ℃ / min in a box furnace with an oxygen concentration of ≥96%, and kept for 2 h, then heated to 740 ℃ and kept for 12 h, naturally cooled to room temperature, crushed, and sieved through a 300-mesh sieve to obtain a primary sintered material.

[0072] (2) The primary sintered material is washed with deionized water for 3 min, the solid-liquid mass ratio of washing is 1.0, the temperature of deionized water is controlled at 8℃, the stirring rate is 700 rpm / min, after washing, the sample is placed in a vacuum oven, vacuum dried at 160℃ for 6h, then naturally cooled to room temperature, and sieved through a 300 mesh sieve to obtain a nickel-based positive electrode material Li 1.01 Ni 0.929 Co 0.03 Mn 0.04 Zr 0.001 O2.

[0073] Comparative Example 2:

[0074] The nickel-based positive electrode material of the present comparative example has a preparation method comprising the following steps:

[0075] (1) The nickel-cobalt-manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2, lithium hydroxide monohydrate, and zirconium dioxide are added to a high-speed mixing stirrer in a molar ratio of 1:1.05:0.001, stirred at a speed of 1800 r / min for 30 min, then heated to 500℃ at a heating rate of 3℃ / min in a box furnace with an oxygen concentration ≥96%, and kept at 500℃ for 2h, then heated to 740℃ and kept for 12h, naturally cooled to room temperature, crushed, and sieved through a 300 mesh sieve to obtain a primary sintered material.

[0076] (2) The primary sintered material is washed with deionized water for 3 min, the solid-liquid mass ratio of washing is 1.0, the temperature of deionized water is controlled at 8℃, the stirring rate is 700 rpm / min, after washing, the sample is placed in a vacuum oven, vacuum dried at 160℃ for 6h, then naturally cooled to room temperature, and sieved through a 300 mesh sieve to obtain a nickel-based positive electrode material Li 1.01 Ni 0.929 Co 0.03 Mn 0.04 Zr 0.001 O2.

[0077] (3) The water-washed base material and antimony pentoxide are added to a high-speed mixing stirrer in a mass ratio of 1:0.0027, stirred at a speed of 1800 r / min for 30 min, then heated to 200℃ at a heating rate of 3℃ / min in a box furnace under an oxygen atmosphere, kept at 200℃ for 2h, then heated to 400℃ and kept for 4h, then heated to 600℃ and kept for 8h, naturally cooled to room temperature to obtain a sintered material, which is sieved through a 300 mesh sieve to obtain a nickel-based positive electrode material.

[0078] Comparative Example 3:

[0079] The preparation method of the nickel-based positive electrode material of the present comparison comprises the following steps:

[0080] (1) A nickel-cobalt-manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2, lithium hydroxide monohydrate, and zirconium dioxide are added into a high-speed mixing stirrer in a molar ratio of 1:1.05:0.001, stirred at a speed of 1800 r / min for 30 min, then heated to 500℃ at a heating rate of 3℃ / min in a box furnace with an oxygen concentration ≥96%, and kept at 500℃ for 2 h, then heated to 740℃ and kept for 12 h, naturally cooled to room temperature, crushed, and passed through a 300-mesh sieve to obtain a primary sintered material.

[0081] (2) The primary sintered material is washed with deionized water for 3 min, the solid-liquid mass ratio of the washing is 1.0, the temperature of the deionized water is controlled at 8℃, the stirring rate is 700 rpm / min, after washing, the sample is placed in a vacuum oven and vacuum dried at 160℃ for 6 h, then naturally cooled to room temperature, and passed through a 300-mesh sieve to obtain a water-washed base material Li 1.01 Ni 0.929 Co 0.03 Mn 0.04 Zr 0.001 O2.

[0082] (3) The water-washed base material and polyvinylidene fluoride are added into a high-speed mixing stirrer in a mass ratio of 1:0.0017, stirred at a speed of 1800 r / min for 30 min, then heated to 200℃ at a heating rate of 3℃ / min in a box furnace under an oxygen atmosphere, kept at 200℃ for 2 h, then heated to 400℃ and kept for 4 h, then heated to 600℃ and kept for 8 h, naturally cooled to room temperature to obtain a sintered material, the sintered material is sieved using a 300-mesh sieve to obtain a nickel-based positive electrode material.

[0083] Performance test:

[0084] The electrochemical performance of the positive electrode materials in the above examples and comparative examples is studied using CR2032 button cells.

[0085] Positive electrode sheet: the positive electrode materials of Examples 1-3 and Comparative Examples 1-3, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) are stirred and dispersed in a mass ratio of 92.5:5:2.5 with a solvent NMP, coated on an aluminum foil substrate, and roll-pressed to obtain a positive electrode sheet.

[0086] Negative electrode sheet: lithium metal sheet.

[0087] Electrolyte: 1 mol / L LiPF6 solution, solvent is a mixed solvent of EC and DMC in a ratio of 1:2, and additive is 1% VC.

[0088] The battery was assembled into a CR2032 button cell for battery testing, the charge cut-off voltage was 4.35V, and the discharge cut-off voltage was 3.0V.

[0089] The test results of the electrical properties of the positive electrode materials prepared in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1.

[0090] Table 1 Test results of the electrical properties of the positive electrode materials in Examples 1-3 and Comparative Examples 1-3

[0091] As can be seen from Table 1, the nickel-based positive electrode material prepared in Examples 1-3 not only has a simple preparation method, but also can significantly improve the first discharge efficiency, reduce the material DCR, and significantly improve the high-temperature cycle, to a large extent, solving the common problems of low first efficiency, large impedance and poor cycle performance of high-nickel positive electrode materials in the industry. In Example 4, the amount of coating material is too much, resulting in a thick solid-state electrolyte coating layer, and in Example 5, the three-stage sintering system is not used, the coating layer is not uniform, the overall impedance is relatively large, and the capacity, DCR and cycle performance are slightly poor; in Comparative Example 1, no solid-state electrolyte coating layer is used, the surface structure is unstable after water washing, in Comparative Example 2, only lithium, antimony and oxygen are in the coating layer, and the cycle performance is poor, in Comparative Example 3, only fluorine is coated, and a lithium salt coating layer cannot be formed, the overall impedance is large, the capacity, DCR and cycle performance are poor.

Claims

1. A nickel-based positive electrode material, comprising a nickel-based positive electrode material substrate and a solid-state electrolyte coating layer wrapped on the surface of the nickel-based positive electrode material substrate, wherein the solid-state electrolyte coating layer comprises lithium, antimony, fluorine, carbon and oxygen.

2. The nickel-based positive electrode material of claim 1, wherein, The surface of primary particles of the nickel-based positive electrode material is also wrapped with a solid-state electrolyte coating layer.

3. The nickel-based positive electrode material of claim 1 or 2, wherein, The chemical general formula of the nickel-based positive electrode material matrix is Li z Ni 1-x-y-u Co x Me y M u O 2-v , wherein 0.9≤z≤1.1, 0≤x≤0.2, 0≤y≤0.2, 0 4. The nickel-based positive electrode material of any one of claims 1-3, wherein, The solid-state electrolyte coating layer is a composite coating layer of LiSbO 3, LiSbF 6 and Li 2 CO 3, and the molar ratio of LiSbO 3, LiSbF 6 and Li 2 CO 3 is 1-7.5: 1.2-4.6: 1.75-30.

5.

5. The nickel-based positive electrode material of any one of claims 1-4, wherein, The mass of the solid-state electrolyte coating layer is 0.2wt%-2wt% of the mass of the nickel-based positive electrode material substrate.

6. The nickel-based positive electrode material of any one of claims 1-5, wherein, The specific surface area of the nickel-based positive electrode material is 0.2-1.2 m 2 / g, the particle size of primary particles thereof is 140-250 nm, and the residual lithium is 500-2000 ppm. 7.A method for preparing the nickel-based positive electrode material according to any one of claims 1-6, comprising the following steps: (1) mixing a positive electrode material precursor, a lithium source and a dopant containing a doping element M uniformly and then performing sintering treatment to obtain a sintered product; (2) performing water washing and drying on the sintered product obtained in step (1) to obtain a water-washed product; (3) mixing the water-washed product obtained in step (2) with an antimony source and a fluorine source uniformly and then performing sintering to obtain the nickel-based positive electrode material.

8. The production method according to claim 7, wherein In step (3), the sintering treatment comprises three-stage sintering, first-stage sintering at 100-300℃ for 1-5h, second-stage sintering at 300-500℃ for 2-12h and third-stage sintering at 500-700℃ for 4-15h.

9. The production method according to any one of claims 7 to 8, wherein In step (3), the addition amount of the antimony source is 1000-4000ppm of the mass of the antimony element based on the mass of the water-washed product, and the addition amount of the fluorine source is 500-2000ppm of the mass of the fluorine element based on the mass of the water-washed product.

10. The production method according to any one of claims 7 to 9, wherein In step (1), the sintering treatment comprises two-stage sintering, first-stage sintering at 400-600℃ for 2-5h and second-stage sintering at 600-800℃ for 8-20h.

11. The production method according to any one of claims 7 to 10, wherein The lithium source is one or more of lithium hydroxide, lithium carbonate or lithium nitrate.

12. The production method according to any one of claims 7 to 11, wherein The dopant containing a doping element M is selected from one or more of oxides, hydroxides, nitrates, phosphates or sulfates containing the doping element M.

13. The production method according to any one of claims 7 to 12, wherein The antimony source is one or more of diantimony trioxide, diantimony pentoxide, antimony trisulfide or antimony trifluoride.

14. The production method according to any one of claims 7 to 13, wherein The fluorine source comprises at least one of lithium fluoride, polyvinylidene fluoride, polytrifluorochloroethylene or polytetrafluoroethylene.

15. The production method according to any one of claims 7 to 14, wherein In step (2), the water washing is performed at a temperature of 5-25℃, the solid-liquid mass ratio in the water washing process is 0.8-1.5, and the stirring speed in the water washing process is 400-900rpm. 16.A lithium ion battery comprising the nickel-based positive electrode material according to any one of claims 1-6 or prepared by the method according to any one of claims 7-15. 17.An electric device comprising the lithium ion battery according to claim 16.

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