High-voltage medium-nickel ternary positive electrode material, preparation method thereof and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion battery materials, and discloses a high-voltage medium-nickel ternary positive electrode material, a preparation method thereof and a lithium ion battery. The high-voltage medium-nickel ternary positive electrode material comprises a medium-nickel ternary positive electrode material and a coating layer located on at least part of the surface of the medium-nickel ternary positive electrode material, the coating layer is obtained by sintering a coating precursor, and the coating precursor comprises solid butadiene sulfone, lithium bis (trifluoromethane sulfonyl) imide, cobaltous hydroxide and aluminum hydroxide. The preparation method comprises the following steps: mixing a hydroxide precursor of a medium-nickel ternary positive electrode material with a lithium salt, and carrying out first sintering to obtain a first sintered material; and mixing the primary sintering material with the coating material, and carrying out secondary sintering to obtain the high-voltage medium-nickel ternary positive electrode material. According to the invention, the high-voltage performance of the medium-nickel ternary positive electrode material is improved, the original capacity and rate capability are maintained, the problem that other performances are sacrificed while the high-voltage performance is improved is avoided, and a detonation phenomenon is not easy to occur.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery materials, and in particular relates to a medium-nickel ternary positive electrode material and a preparation method and application thereof. Background Art

[0002] As an efficient and clean energy storage and conversion device, batteries are increasingly used. Among them, lithium-ion batteries are widely used in electric vehicles, energy storage systems and other fields due to their high energy density, long cycle life and environmental protection. However, the performance of lithium-ion batteries is restricted by the positive electrode material, especially the medium-nickel ternary positive electrode material, which has serious interface stability problems when charging and discharging at high voltage, limiting its application in high voltage fields. To solve this problem, the existing technology mainly changes the chemical composition or structure of the positive electrode material to improve its stability at high voltage. For example, by doping with other elements or coating with other substances, the structural stability of the positive electrode material is improved, thereby improving its high voltage performance.

[0003] CN112086628A discloses a method for preparing a single-crystal high-voltage multi-component composite cathode material. The single-crystal multi-component composite cathode material has a core-shell structure, with the core structure being 3-8 μm-diameter lithium nickel cobalt manganese oxide primary crystal particles and the shell structure being nano-scale zirconium, tungsten, aluminum, and magnesium metal oxides. The high voltage is 4.35-4.40 V. The molar ratio of lithium:nickel:cobalt:manganese:oxygen in the cathode material is 0.03:X:Y:(1-XY):2, where 0.5≤X≤0.9 and 0.05≤Y≤0.2. The combined mass of the nano-scale zirconium, tungsten, aluminum, and magnesium metal oxides accounts for 0.1-1.0% of the mass of the cathode material. The single-crystal multi-component composite cathode material prepared by coating the lithium nickel cobalt manganese oxide primary crystal particles with nano-scale metal oxides effectively improves its gram-specific capacity, cycle performance, rate capability, and thermal stability, and reduces its internal resistance and self-discharge in lithium-ion battery applications. The material is highly suitable for lithium-ion batteries in the 3C, power, and energy storage sectors. However, the introduction of tungsten can lead to subsequent metal dissolution problems, resulting in deterioration of battery storage performance.

[0004] CN111276681A discloses a positive electrode material, a preparation method and application thereof, a positive electrode, and a battery. This method uses a CuF2-coated nickel-cobalt-manganese oxide ternary material to form a positive electrode material, which can be made into a positive electrode and further applied to batteries such as lithium-ion batteries. On the one hand, it promotes the formation of a stable SEI film; on the other hand, it can reduce the impedance of the positive electrode material during the charge and discharge process, and is conducive to maintaining the structural stability of the nickel-cobalt-manganese oxide ternary material, reducing the diffusion resistance of some lithium ions and increasing the diffusion rate of lithium ions, thereby improving the electrochemical properties of the positive electrode material at higher voltages, such as rate performance and cycle performance, especially at higher voltages. The use of CuF2 coating introduces fluoride ions, and the hydrofluoric acid produced during the cycle process has a corrosive effect on the positive electrode surface, ultimately causing serious storage gas production problems.

[0005] In addition, while existing technologies improve the high-voltage performance of positive electrode materials, they often sacrifice other properties of the materials, such as capacity and rate performance; and they involve complex preparation processes and expensive raw materials, which increases the cost of the battery and limits its large-scale application.

[0006] Improving the high voltage performance of medium-nickel ternary positive electrode materials and reducing costs without sacrificing other battery properties is an important challenge facing current battery material preparation technology. Summary of the Invention

[0007] In response to the problems existing in the prior art, the first purpose of the present invention is to provide a high-voltage medium-nickel ternary positive electrode material; the second purpose of the present invention is to provide a method for preparing a high-voltage medium-nickel ternary positive electrode material; and the third purpose of the present invention is to provide a battery.

[0008] To achieve the above objectives, the present invention provides the following specific technical solutions.

[0009] In a first aspect, the present invention provides a high-voltage medium-nickel ternary positive electrode material, comprising a medium-nickel ternary positive electrode material and a coating layer located on at least a portion of the surface of the medium-nickel ternary positive electrode material; the coating layer is obtained by sintering a coating precursor, and the coating precursor is composed of solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide.

[0010] In a further preferred embodiment, the chemical formula of the nickel ternary positive electrode material is Li a Ni x Co y Mn 1-x-y O2, 0.5≤x≤0.79, 0.05≤y≤0.2, 1≤a≤1.1, 1.65≤x+y+a≤2.0.

[0011] In a further preferred embodiment, 0.6≤x≤0.7.

[0012] In a further preferred embodiment, the mass of the coating layer is 1% to 2% of the mass of the medium-nickel ternary positive electrode material.

[0013] In a further preferred embodiment, the molar ratio of the solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide is a:b:c:d=0.5-1.5:0.5-1.5:4-15:0.5-1.5.

[0014] In a further preferred embodiment, the sintering temperature is 600-800° C., and the sintering time is 10 h-15 h.

[0015] In a further preferred embodiment, the specific surface area of ​​the high voltage nickel ternary positive electrode material is 0.8 to 1.2 m 2 / g, particle size D50 is 2.0~4.0μm, and tap density is 2~3g / cm 3 .

[0016] In a second aspect, the present invention provides a method for preparing a high-voltage medium-nickel ternary positive electrode material, comprising: Mixing the hydroxide precursor and lithium salt of the medium nickel ternary cathode material and performing a first sintering to obtain a first-fired material; The first sintered material is mixed with the coated material and sintered for the second time to obtain a high-voltage medium-nickel ternary positive electrode material; The coating material comprises solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide.

[0017] In a further preferred embodiment, the general chemical formula of the hydroxide precursor of the nickel ternary cathode material is Ni x Co y Mn 1-x-y (OH)2, where 0.6≤x≤0.7, 0.05≤y≤0.2.

[0018] In a further preferred embodiment, the lithium salt is at least one of lithium carbonate and lithium hydroxide.

[0019] In a further preferred embodiment, the molar ratio of the hydroxide precursor to the lithium in the lithium salt is 1:1 to 1.06.

[0020] In a further preferred embodiment, the temperature of the first sintering is 900° C. to 950° C., and the time of the first sintering is 10 h to 15 h.

[0021] In a further preferred embodiment, the molar ratio of solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide in the coating material is a:b:c:d=0.5~1.5:0.5~1.5:4~15:0.5~1.5.

[0022] In a further preferred embodiment, the mass of the coating material is 1% to 2% of the mass of the fired material.

[0023] In a further preferred embodiment, the temperature of the second sintering is 600-800° C., and the time of the second sintering is 10 h-15 h.

[0024] In a further preferred embodiment, the calcined material and the coating material are mixed by dispersing the coating material in a liquid dispersion medium and then spraying the mixture onto the surface of the calcined material.

[0025] Furthermore, the liquid dispersion medium is water or ethanol.

[0026] Furthermore, during the spraying process, the materials are stirred and burned.

[0027] Furthermore, after the spraying is completed, the material is dried and burned.

[0028] Based on the same inventive concept, the present invention provides a lithium-ion battery, comprising the aforementioned high-voltage medium-nickel ternary positive electrode material or the high-voltage medium-nickel ternary positive electrode material prepared by the aforementioned preparation method.

[0029] Compared with the prior art, the above one or more technical solutions of the present invention can achieve at least one of the following beneficial effects: It not only improves the high voltage performance of the medium nickel ternary positive electrode material, but also maintains its original capacity and rate performance, avoiding the problem of sacrificing other performance while improving high voltage performance.

[0030] When the high-voltage medium-nickel ternary positive electrode material provided by the present invention is applied to a battery, the battery is less likely to explode even under high-temperature thermal failure conditions, thereby improving the safety performance of the battery.

[0031] After the high-voltage medium-nickel ternary positive electrode material provided by the present invention is applied to a battery, the battery has excellent cycle performance.

[0032] The preparation method of the present invention is simple and the raw materials are inexpensive, which is beneficial to reducing the preparation cost of the battery and promoting the large-scale application of medium-nickel ternary positive electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The figures are the test results of thermal decomposition temperature of the positive electrode materials obtained in Example 1 and Comparative Example 1 and the discharge capacity of the assembled batteries.

[0034] Figure 2 This is a high voltage discharge cycle performance diagram of a battery assembled with the positive electrode materials obtained in Example 1 and Comparative Example 1.

[0035] Figure 3 This is a high voltage discharge cycle performance diagram of batteries assembled with the positive electrode materials obtained in Example 1 and Comparative Examples 2 to 6.

[0036] Figure 4 The high voltage cycle performance of the battery assembled with the positive electrode materials obtained in Examples 1 to 4. DETAILED DESCRIPTION

[0037] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

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

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

[0040] Example 1 10 kg of precursor Ni 0.65 Co 0.15 Mn 0.20 (OH)2 and 4.7 kg of LiOH were mixed evenly, and then heated to 930°C at a heating rate of 2°C / min in an oxygen atmosphere with an oxygen concentration of 90% to 100%, and sintered at a constant temperature for 12 hours. After the sintering, the mixture was cooled to room temperature and crushed to obtain a sintered product.

[0041] Solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide are mixed in a molar ratio of 1:1:10:1 to obtain a coating material.

[0042] 100 g of the coated material was weighed and dispersed in 2 L of water to obtain a suspension.

[0043] The calcined material is placed in a high-speed mixer, and the paddles rotate to spray the suspension onto the surface of the calcined material through a conveyor pipe. After spraying, the calcined material is dried and then transferred to a roller kiln for sintering at 750°C for 8 hours in an oxygen atmosphere with an oxygen concentration of 90% to 100%. After sintering, it is cooled to room temperature to obtain the positive electrode material.

[0044] Comparative Example 1 10 kg of precursor Ni 0.65 Co 0.15 Mn 0.20 (OH)2 and 4.7 kg of LiOH were mixed evenly, and then heated to 930 ° C at a heating rate of 2 ° C / min in an oxygen atmosphere with an oxygen concentration of 90% ~ 100% and sintered at a constant temperature for 12 hours; after the sintering was completed, it was cooled to room temperature and crushed to obtain a sintered product, i.e., the positive electrode material.

[0045] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that the coating material is lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide, and aluminum hydroxide mixed in a molar ratio of 1:10:1.

[0046] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that the coating material is a mixture of solid butadiene sulfone, cobaltous hydroxide, and aluminum hydroxide in a molar ratio of 1:10:1.

[0047] Comparative Example 4 The only difference between Comparative Example 4 and Example 1 is that the coating material is a mixture of solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), and aluminum hydroxide in a molar ratio of 1:1:1.

[0048] Comparative Example 5 The only difference between Comparative Example 5 and Example 1 is that the coating material is a mixture of solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), and cobaltous hydroxide in a molar ratio of 1:1:10.

[0049] Comparative Example 6 The only difference between Comparative Example 6 and Example 1 is that solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide, and aluminum hydroxide are directly mixed in a high-pressure mixer in a molar ratio of 1:1:10:1 without spray coating to obtain a coated material.

[0050] Example 2 10 kg of precursor Ni was mixed with a high-speed mixer. 0.60 Co 0.10 Mn 0.30 (OH)2 and 4.7 kg LiOH were mixed evenly, and then heated to 950 ° C at a heating rate of 2 ° C / min in an oxygen atmosphere with an oxygen concentration of 90% to 100%, and sintered at a constant temperature for 10 hours; after the sintering was completed, it was cooled to room temperature and crushed to obtain a sintered product.

[0051] Solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide are mixed in a molar ratio of 1:1:10:1 to obtain a coating material.

[0052] 150 g of the coated material was weighed and dispersed in 2 L of water to obtain a suspension.

[0053] The calcined material is placed in a high-speed mixer, and the paddles rotate to spray the suspension onto the surface of the calcined material through a conveyor pipe. After spraying, the calcined material is dried and then transferred to a roller kiln for sintering at 600°C for 15 hours in an oxygen atmosphere with an oxygen concentration of 90% to 100%. After sintering, it is cooled to room temperature to obtain the positive electrode material.

[0054] Example 3 10 kg of precursor Ni was mixed with a high-speed mixer. 0.63 Co 0.08 Mn 0.29 (OH)2 and 4.7 kg LiOH were mixed evenly, and then heated to 900 °C at a heating rate of 2 °C / min in an oxygen atmosphere with an oxygen concentration of 90% to 100%, and sintered at a constant temperature for 15 hours; after sintering, cooled to room temperature, crushed, and obtained a sintered product.

[0055] Solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide are mixed in a molar ratio of 1:1:8:1 to obtain a coating material.

[0056] Weigh 200 g of the coated material and disperse it in 2 L of water to obtain a suspension.

[0057] The calcined material is placed in a high-speed mixer, and the paddles rotate to spray the suspension onto the surface of the calcined material through a conveyor pipe. After spraying, the calcined material is dried and then transferred to a roller kiln for sintering at 800°C for 10 hours in an oxygen atmosphere with an oxygen concentration of 90% to 100%. After sintering, it is cooled to room temperature to obtain the positive electrode material.

[0058] Example 4 10 kg of precursor Ni 0.70 Co 0.10 Mn 0.20 (OH)2 and 4.7 kg of LiOH were mixed evenly, and then heated to 920°C at a heating rate of 2°C / min in an oxygen atmosphere with an oxygen concentration of 90% to 100%, and sintered at a constant temperature for 12 hours. After the sintering, the mixture was cooled to room temperature and crushed to obtain a sintered product.

[0059] Solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide are mixed in a molar ratio of 1:1:4:1 to obtain a coating material.

[0060] 120 g of the coated material was weighed and dispersed in 2 L of water to obtain a suspension.

[0061] The calcined material is placed in a high-speed mixer, and the paddles rotate to spray the suspension onto the surface of the calcined material through a conveyor pipe. After spraying, the calcined material is dried and then transferred to a roller kiln for sintering at 700°C for 12 hours in an oxygen atmosphere with an oxygen concentration of 90% to 100%. After sintering, it is cooled to room temperature to obtain the positive electrode material.

[0062] The specific surface area, particle size and tap density of the positive electrode materials obtained in each embodiment and comparative example were tested, and the results are shown in Table 1.

[0063] Table 1 Among them, the specific surface area is tested by a specific surface analyzer / static method, the particle size is tested by a laser particle size analyzer, and the tap density is tested by a tap density tester.

[0064] Preparation of button cells (1) Preparation of positive electrode The positive electrode materials prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were mixed with the conductive agent SuperP, the binder polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) in a mass ratio of 90:5:5 and stirred evenly to prepare a positive electrode slurry (solid content of 40%). The slurry was coated on the current collector aluminum foil, dried at 105°C, and then rolled at room temperature to a surface density of 2.8-3.3 g / cm 3 , then punched and cut into φ14mm discs to make positive electrode sheets.

[0065] (2) Assembly of lithium-ion batteries Button cells were assembled in a glove box in the following order: negative electrode shell - nickel foam - lithium sheet - 8 drops of electrolyte - separator - 8 drops of electrolyte - positive electrode sheet - positive electrode shell. The electrolyte consisted of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) (EC:EMC:DMC volume ratio = 1:1:1), containing 1.0M LiPF6.

[0066] The diameter of the positive electrode sheet is 14 mm, the diameter of the lithium sheet is 18 mm, the diameter of the separator is 22 mm, and the battery case (positive and negative) is 24 mm. The separator is a 16 μm thick isolating membrane. The assembled button cell is placed in the mold cavity of a hydraulic sealing machine (purchased from Shenzhen Kejing Zhida Technology Co., Ltd.) and locked, applying a pressure of >450 kg / cm. 2 , then unlock it and take out the sealed button battery.

[0067] Button battery performance test (1) Capacity and cycle capacity retention test: At 25°C, the charge and discharge cycle characteristics of the button battery were tested using a blue electric test cabinet. The battery was charged and discharged at a charge and discharge rate of 0.1C in the voltage range of 2.8V~4.4V. Specifically, the battery was charged at a constant current of 0.1C to 4.4V, then charged at a constant voltage of 4.4V for 1h, left for 5min, and discharged at a constant current of 0.1C to 2.8V, left for 5min, and the charge and discharge capacity after the first cycle was recorded.

[0068] Again, charge at a constant current of 1C to 4.4V, then charge at a constant voltage of 4.4V for 1h, rest for 5min, discharge at 1C to 2.8V, rest for 5min, and repeat this cycle. After 200-800 charge / discharge cycles, record the charge and discharge capacity after the third cycle and calculate the discharge capacity retention rate of the battery after the cycle.

[0069] (2) Rate discharge performance test: At 25°C, the charge and discharge cycle characteristics of the button battery were tested using a blue electric test cabinet. The first week of charge and discharge activation was carried out at a charge and discharge rate of 0.1C. In the second week, the battery was charged and discharged at a voltage range of 2.8V~4.4V at a rate of 2C. Specifically, the battery was charged to 4.4V at a constant current of 2C, then charged at a constant voltage of 4.4V for 1h, left for 5min, discharged to 2.8V at 2C, and left for 5min. The charge and discharge capacity after the first cycle was recorded.

[0070] 2C discharge capacity retention rate (%) = 2C discharge capacity / 0.1C discharge capacity × 100% The thermal decomposition temperature is determined by the following method: at 25°C, the battery is charged and discharged for one cycle at a charge and discharge rate of 0.1C in the voltage range of 2.8V~4.4V using a blue electric test cabinet; after the second cycle is charged to 4.4V at 0.1C, the battery is moved to a glove box for disassembly, the positive electrode plate is taken out, and then the positive electrode plate is cleaned and dried with DMC solvent, and then the electrolyte is added (electrolyte weight / positive electrode plate load material mass = 0.55); finally, the sample to be tested is placed in the crucible of the synchronous thermal analyzer, and heated to 400°C at a heating rate of 5°C / min in a nitrogen atmosphere, and the material mass change value during the test process is recorded.

[0071] The test results are shown in Table 2. Figures 1 to 4 shown.

[0072] Table 2 Table 2 shows the charge and discharge capacity and 2C rate discharge capacity retention of batteries assembled with the positive electrode materials of each embodiment and comparative example, and also tests the thermal decomposition temperature of the positive electrode materials of each embodiment and comparative example.

[0073] As can be seen from Table 2, compared to the various comparative examples, in Example 1, coating the positive electrode material with the sintered product of solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide, and aluminum hydroxide substantially did not affect the battery's charging performance, improved the discharge capacity and rate capability, and significantly increased the thermal decomposition temperature. When the coating material was three of solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide, and aluminum hydroxide (i.e., Comparative Examples 2-5), the thermal decomposition temperature of the positive electrode material was significantly lower than that of the positive electrode material obtained in Example 1.

[0074] In addition, the different mixing methods of the coating material and the positive electrode material in Example 1 and Comparative Example 6 also have a certain impact on the thermal decomposition temperature of the positive electrode material. The spraying mixing method makes the thermal decomposition temperature of the positive electrode material as high as 273.15°C, but the thermal decomposition temperature of the positive electrode material obtained by the solid phase mixing mixing method is 262.17°C.

[0075] Figure 1 The discharge capacity and thermal decomposition temperature of the cathode materials finally obtained in Example 1 and Comparative Example 1 are shown. It can be seen that the thermal decomposition temperature of the cathode materials is increased after coating.

[0076] from Figure 2 It can be seen that the positive electrode material obtained in Example 1 can greatly improve the high voltage cycle performance of the battery compared to Comparative Example 1. That is, coating with a specific material can greatly improve the high voltage cycle performance of the battery.

[0077] In addition, from Figure 3 It can also be seen that the high-voltage cycling performance of the battery assembled with the cathode material prepared in Example 1 is superior to that of Comparative Examples 2 to 5. This demonstrates that the choice of coating material is crucial for improving the performance of the cathode material. Solid butadiene sulfone, lithium bis(trifluoromethanesulfonylimide), cobaltous hydroxide, and aluminum hydroxide are essential components of the coating material.

[0078] Similarly, the positive electrode materials obtained in Examples 2 to 4 also enable the battery to have good high-voltage cycle performance.

[0079] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A high voltage nickel ternary cathode material, characterized in that: It includes a medium-nickel ternary positive electrode material and a coating layer located on at least a portion of the surface of the medium-nickel ternary positive electrode material; the coating layer is obtained by sintering a coating precursor, and the coating precursor includes solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide.

2. The high-voltage nickel ternary cathode material according to claim 1, characterized in that: The general chemical formula of the nickel ternary cathode material is Li a Ni x Co y Mn 1-x-y O2, 0.5≤x≤0.79, 0.05≤y≤0.2, 1≤a≤1.1, 1.65≤x+y+a≤2.0; among them, Preferably, 0.6≤x≤0.7; Preferably, the mass of the coating layer is 1% to 2% of the mass of the medium nickel ternary positive electrode material; Preferably, the molar ratio of the solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide is a:b:c:d=0.5-1.5:0.5-1.5:4-15:0.5-1.

5.

3. The high-voltage nickel ternary cathode material according to claim 1 or 2, characterized in that: The sintering temperature is 600-800°C; Preferably, the sintering time is 10h~15h.

4. The high-voltage medium-nickel ternary cathode material according to claim 1, characterized in that: The specific surface area of ​​the high-voltage nickel ternary positive electrode material is 0.8-1.2 m 2 / g; Preferably, the particle size D50 of the high voltage nickel ternary positive electrode material is 2.0-4.0 μm; Preferably, the tap density of the high voltage nickel ternary positive electrode material is 2-3 g / cm 3 .

5. A method for preparing a high-voltage nickel ternary positive electrode material, characterized in that: include: Mixing the hydroxide precursor and lithium salt of the medium nickel ternary cathode material and performing a first sintering to obtain a first-fired material; The first sintered material is mixed with the coated material and sintered for the second time to obtain a high-voltage medium-nickel ternary positive electrode material; The coating material comprises solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide.

6. The preparation method according to claim 5, wherein The general chemical formula of the hydroxide precursor of the nickel ternary cathode material is Ni x Co y Mn 1-x-y (OH)2, where 0.6≤x≤0.7, 0.05≤y≤0.2； Preferably, the lithium salt is at least one of lithium carbonate and lithium hydroxide; Preferably, the molar ratio of the hydroxide precursor to the lithium salt is 1:1 to 1.

06.

7. The preparation method according to claim 5 or 6, characterized in that The temperature of the first sintering is 900° C.-950° C., and the time of the first sintering is 10 h-15 h.

8. The preparation method according to claim 5 or 6, characterized in that The molar ratio of solid butadiene sulfone, lithium bis(trifluoromethanesulfonyl imide), cobaltous hydroxide and aluminum hydroxide in the coating material is a:b:c:d=0.5-1.5:0.5-1.5:4-15:0.5-1.5; Preferably, the mass of the coating material is 1% to 2% of the mass of the burnt material; Preferably, the temperature of the second sintering is 600-800° C., and the time of the second sintering is 10 h-15 h.

9. The preparation method according to any one of claims 5 to 8, wherein The method of mixing the burnt material and the coating material is as follows: the coating material is dispersed in a liquid dispersion medium and then sprayed onto the surface of the burnt material; Preferably, the liquid dispersion medium is water or ethanol; Preferably, during the spraying process, the burning material is stirred; Preferably, after the spraying is completed, the material is dried and burned.

10. A lithium ion battery, characterized in that: The invention comprises the high-voltage medium-nickel ternary positive electrode material according to any one of claims 1 to 4 or the high-voltage medium-nickel ternary positive electrode material prepared by the preparation method according to any one of claims 5 to 9.

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