A ternary cathode material, its preparation method and application

Abstract

The present invention provides a ternary cathode material, a preparation method thereof and an application. The preparation method includes the following steps: (1) Mix sodium alginate and a solvent and then perform atomization treatment. Mix a nickel source, a cobalt source and a manganese source with the solvent and then add a lithium source to obtain a mixed solution; (2) Spray the atomized sodium alginate solution into the mixed solution for reaction. After the reaction is completed, perform solid-liquid separation to obtain a gel; (3) Perform freeze-drying treatment on the gel to obtain an intermediate, and perform calcination treatment on the intermediate to obtain the ternary cathode material. The method of the present invention can obtain a ternary cathode material with excellent performance without high-temperature calcination on the premise of not affecting the overall structural stability and performance of the material, and can obtain a ternary cathode material with a more uniform particle size distribution, a smaller average particle size and a larger specific surface area while reducing energy consumption.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and relates to a ternary cathode material, a preparation method thereof, and an application thereof. Background Art

[0002] At present, the mainstream power sources of new energy vehicles are divided into two categories. One is hydrogen energy technology, and the other is lithium-ion battery technology. At present, the safety problem of hydrogen energy is still a huge hidden danger. Therefore, lithium-ion batteries will still be the mainstream technical route in the next few decades. Currently, commercially available lithium-ion batteries are mainly divided into two categories: one is the polyanion type represented by lithium iron phosphate, and the other is the layered oxide type represented by lithium nickel cobalt manganese oxide.

[0003] As a cathode material, lithium nickel cobalt manganese oxide has a high energy density and excellent low-temperature performance, so it has long occupied the market priority. However, with the rising price of lithium salts globally, lithium iron phosphate gradually has an advantage over lithium nickel cobalt manganese oxide in terms of comprehensive cost. However, the energy density of lithium iron phosphate is much lower than that of lithium nickel cobalt manganese oxide, which limits the market's pursuit of electric vehicles with longer cruising ranges. In order to reduce the production cost of lithium nickel cobalt manganese oxide, it is necessary to optimize its process from the material end.

[0004] CN115215388A discloses a preparation method of a ternary cathode material and the ternary cathode material. The method includes: mixing a manganese salt and / or an aluminum salt with a nickel salt and a cobalt salt, and performing a coprecipitation reaction with an alkaline substance and a complexing agent in a solvent to obtain a coprecipitation slurry with a target median particle size; washing the coprecipitation slurry to obtain a ternary precursor slurry; in an inert atmosphere, mixing a lithium source with the ternary precursor slurry, drying, and then performing a high-temperature sintering treatment to obtain the ternary cathode material.

[0005] CN105261737A discloses a preparation method of a ternary cathode material. The method includes: Step 1: Mixing a salt ingredient and an alkali ingredient uniformly by a solution method to form a mixed solution; Step 2: Precipitating the mixed solution in Step 1 to form precursor crystals, and controlling the nucleation and crystal growth rates of the coprecipitation reaction by adjusting parameters; Step 3: Washing and pressure-filtering the precursor crystals formed in Step 2, adding cations to the liquid phase for doping modification, and then performing a drying treatment; Step 4: Adding lithium to the dried raw material, then performing roasting, and then performing surface coating modification to obtain a ternary material product.

[0006] The above solutions prepare a precursor by a coprecipitation method and then perform high-temperature roasting to prepare a cathode material. In order to reduce the residual alkali on the surface and improve the structural stability and reaction activity, water washing, secondary sintering, and even three-time sintering and other treatment means are often accompanied. This process route has high requirements for reaction equipment and reaction conditions, and at the same time has high energy consumption, greatly increasing the production cost. Summary of the Invention

[0007] The object of the present invention is to provide a ternary cathode material, a preparation method and an application thereof. The method of the present invention can prepare a ternary cathode material with excellent performance without high-temperature calcination on the premise of not affecting the overall structural stability and performance of the material, and can obtain a ternary cathode material with a more uniform particle size distribution, a smaller average particle size and a larger specific surface area while reducing energy consumption.

[0008] To achieve the object of this invention, the following technical solutions are adopted:

[0009] In the first aspect, the present invention provides a preparation method of a ternary cathode material, and the preparation method includes the following steps:

[0010] (1) Atomize the sodium alginate solution, mix the nickel source, cobalt source and manganese source with a solvent, and then add a lithium source to obtain a mixed solution;

[0011] (2) Spray the atomized sodium alginate solution into the mixed solution for reaction, and perform solid-liquid separation after the reaction to obtain a gel;

[0012] (3) Perform freeze-drying treatment on the gel to obtain an intermediate, and perform calcination treatment on the intermediate to obtain the ternary cathode material.

[0013] In the method of the present invention, the sodium alginate liquid flow will spontaneously disperse to form droplets with a diameter of dozens of micrometers under the action of an electric field force or high-frequency vibration; after contacting with transition metal ions and lithium ions, the transition metal ions and lithium ions will undergo an ion exchange reaction with sodium ions in the droplets to form a nickel cobalt manganese-lithium composite gel of sodium alginate; then, after calcining the intermediate, a powder product is obtained, and the temperature during the calcination process is significantly lower than that of the traditional high-temperature solid-phase method.

[0014] Preferably, the molecular weight of the sodium alginate in step (1) is 50,000 to 80,000, such as: 50,000, 60,000, 70,000 or 80,000, etc.

[0015] Preferably, the mass ratio of the sodium alginate to the solvent is 1:(80-120), such as: 1:80, 1:90, 1:100, 1:110 or 1:120, etc.

[0016] Preferably, the temperature of the mixing is 40-60°C, such as: 40°C, 45°C, 50°C, 55°C or 60°C, etc.

[0017] Preferably, the atomization treatment in step (1) includes pumping the sodium alginate solution through a peristaltic pump to a spray port, and applying vibration at the spray port so that the sodium alginate is ejected in the form of tiny droplets.

[0018] The atomization treatment in the present invention atomizes the sodium alginate solution from the front end by applying an electric field or high-frequency vibration to form droplets with a particle size of about 50 microns. The sodium alginate solution is transported to the spray port by pumping; subsequently, the droplets fall into the mixed solution under the action of gravity.

[0019] Preferably, the diameter of the spray port is 120 - 180 μm, such as: 120 μm, 130 μm, 150 μm, 160 μm or 180 μm, etc.

[0020] Preferably, the frequency of the vibration is 200 - 400 Hz, such as: 200 Hz, 250 Hz, 300 Hz, 350 Hz or 400 Hz, etc.

[0021] Preferably, the nickel source includes any one or a combination of at least two of nickel chloride, nickel sulfate or nickel nitrate.

[0022] Preferably, the manganese source includes any one or a combination of at least two of nickel chloride, manganese sulfate or manganese nitrate.

[0023] Preferably, the cobalt source includes any one or a combination of at least two of cobalt chloride, cobalt sulfate or cobalt nitrate.

[0024] Preferably, the lithium source includes any one or a combination of at least two of lithium hydroxide, lithium chloride or lithium sulfate.

[0025] Preferably, stirring is carried out while spraying in step (2).

[0026] After the dropped sodium alginate droplets are mixed with the solution, a chelation reaction occurs rapidly to form a nickel cobalt manganese-lithium composite gel structure. At the same time, continuous stirring is carried out in the container to maintain a consistent reaction rate and prevent segregation.

[0027] Preferably, the stirring speed is 50 - 70 rpm, such as: 50 rpm, 55 rpm, 60 rpm, 65 rpm or 70 rpm, etc.

[0028] Preferably, washing treatment is carried out after solid-liquid separation.

[0029] Preferably, the detergent for the washing treatment includes deionized water.

[0030] After the washing treatment, the free acid root anions in the gel will be removed, reducing the influence on the subsequent process.

[0031] Preferably, the temperature of the freeze-drying treatment in step (3) is -30 to -15 °C, such as: -30 °C, -25 °C, -20 °C, -18 °C or -15 °C, etc.

[0032] Preferably, the time for the freeze-drying treatment is 0.8 to 1.2 h, such as: 0.8 h, 0.9 h, 1 h, 1.1 h, or 1.2 h, etc.

[0033] In the present invention, the gel is treated by freeze-drying to remove moisture to obtain an intermediate. Freeze-drying can maintain the structural stability and maximize the product consistency.

[0034] Preferably, the atmosphere for the calcination treatment in step (3) includes an oxygen atmosphere.

[0035] Preferably, the temperature for the calcination treatment is 300 to 400 °C, such as: 300 °C, 320 °C, 350 °C, 380 °C, or 400 °C, etc.

[0036] Preferably, the time for the calcination treatment is 4 to 8 h, such as: 4 h, 5 h, 6 h, 7 h, or 8 h, etc.

[0037] Preferably, a grinding treatment is performed after the calcination treatment in step (3).

[0038] Preferably, the speed of the grinding treatment is 60 to 100 rpm, such as: 60 rpm, 70 rpm, 80 rpm, 90 rpm, or 100 rpm, etc.

[0039] Finally, the powder product is mechanically ground in a high-energy ball mill. After grinding, the particle size distribution of the product is more uniform, the D50 decreases, the specific surface area increases, and the reaction activity is improved.

[0040] In a second aspect, the present invention provides a ternary cathode material, which is prepared by the method as described in the first aspect.

[0041] In a third aspect, the present invention provides a positive electrode sheet, which comprises the ternary cathode material as described in the second aspect.

[0042] In a fourth aspect, the present invention provides a lithium-ion battery, which comprises the positive electrode sheet as described in the third aspect.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The present invention uses sodium alginate as a chelating agent to form a composite gel between the lithium source and transition metal ions. This process significantly reduces energy consumption and production costs compared to the traditional high-temperature solid-state sintering method. During the traditional high-temperature solid-state sintering process, a very high energy is required for lithium to diffuse into the metal phase, resulting in high energy consumption. However, in this gel method, the energy required for the combination of lithium and transition metals is greatly reduced due to the chemical driving force, thus reducing energy consumption and production costs. At the same time, combined with freeze-drying treatment, the stability and consistency of the system structure are improved. Finally, by high-energy ball milling the product, the particle size distribution of the product becomes more uniform, the average particle size is smaller, the specific surface area increases, and the reaction activity is enhanced.

[0045] (2) The NCM811 cathode material prepared by the spray gel method has a specific capacity of 216.3 mAh / g at 0.1C, and the capacity retention rate is as high as 96.5% after 50 cycles at 1C; the NCM613 cathode material has a specific capacity of 190.3 mAh / g at 0.1C, and the capacity retention rate is as high as 97.3% after 50 cycles at 1C. Compared with the traditional high-temperature solid-state sintering method, the specific capacity and cycle stability of the materials are improved. Detailed implementation methods

[0046] The technical solution of the present invention will be further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0047] Example 1

[0048] This example provides a ternary cathode material, and the preparation method of the ternary cathode material is as follows:

[0049] (1) Weigh 10 g of sodium alginate powder (molecular weight 50000 - 80000), add it to 1 L of pure water, heat it in a water bath at 50 °C and stir mechanically to dissolve the sodium alginate powder to form a solution. Weigh 69.79 g of nickel nitrate hexahydrate, 8.73 g of cobalt nitrate hexahydrate, and 8.61 g of manganese nitrate hexahydrate and add them to a container. Stir evenly and then add 12.98 g of lithium hydroxide monohydrate to obtain a mixed solution;

[0050] (2) Use a peristaltic pump to extract the sodium alginate solution and transport it to the spray nozzle. The diameter of the spray nozzle is 150 μm. Apply a vibration with a frequency of 300 Hz at the spray nozzle to make the sodium alginate spray in the form of tiny droplets. The droplets at the spray nozzle fall into the mixed solution, and continuous magnetic stirring is carried out, with a stirring speed of 60 rpm. After the reaction is completed, pour off the supernatant in the container, separate the bottom gel by filtration, and wash it with deionized water;

[0051] (3) The gel was freeze-dried in a freeze dryer at -20 °C for 1 h to obtain an intermediate. Subsequently, the intermediate was calcined under the protection of an oxygen atmosphere. The calcination temperature was 350 °C, and the constant temperature was maintained for 6 h. The heating rate was 3 °C / min. Finally, the calcined product was ground in a high-energy ball mill at a rotation speed of 80 rpm to obtain the NCM811 material.

[0052] Example 2

[0053] This example provides a ternary cathode material, and the preparation method of the ternary cathode material is as follows:

[0054] (1) Weigh 10 g of sodium alginate powder (molecular weight 50000 - 80000), add it to 105 L of clear water, heat it in a water bath at 52 °C and stir mechanically to dissolve the sodium alginate powder to form a solution. Weigh 69.79 g of nickel nitrate hexahydrate, 8.73 g of cobalt nitrate hexahydrate, and 8.61 g of manganese nitrate hexahydrate and add them to a container. Stir evenly and add 16.53 g of lithium chloride to obtain a mixed solution;

[0055] (2) The sodium alginate solution was pumped through a peristaltic pump to the spray nozzle. The diameter of the spray nozzle was 150 μm. Vibration with a frequency of 320 Hz was applied at the spray nozzle so that the sodium alginate was ejected in the form of tiny droplets. The droplets at the spray nozzle fell into the mixed solution, and continuous magnetic stirring was supplemented. The stirring speed was 65 rpm. After the reaction ended, the supernatant in the container was poured off, and the bottom gel was separated by filtration and washed with deionized water;

[0056] (3) The gel was freeze-dried in a freeze dryer at -22 °C for 1 h to obtain an intermediate. Subsequently, the intermediate was calcined under the protection of an oxygen atmosphere. The calcination temperature was 360 °C, and the constant temperature was maintained for 5.5 h. The heating rate was 3 °C / min. Finally, the calcined product was ground in a high-energy ball mill at a rotation speed of 80 rpm to obtain the NCM811 material.

[0057] Example 3

[0058] This example provides a ternary cathode material, and the preparation method of the ternary cathode material is as follows:

[0059] (1) Weigh 10 g of sodium alginate powder (molecular weight 50000 - 80000), add it to 1 L of clear water, heat it in a water bath at 50 °C and stir mechanically to dissolve the sodium alginate powder to form a solution. Weigh 52.34 g of nickel nitrate hexahydrate, 8.73 g of cobalt nitrate hexahydrate, and 25.83 g of manganese nitrate hexahydrate and add them to a container. Stir evenly and add 12.98 g of lithium hydroxide monohydrate to obtain a mixed solution;

[0060] (2) The sodium alginate solution is pumped through a peristaltic pump and delivered to the spray nozzle with a diameter of 150 μm. A vibration with a frequency of 300 Hz is applied at the spray nozzle to eject the sodium alginate in the form of tiny droplets. The droplets at the spray nozzle fall into the mixed solution, and continuous magnetic stirring is supplemented with a stirring speed of 60 rpm. After the reaction is completed, the supernatant liquid in the container is poured off, and the bottom gel is separated by filtration and washed with deionized water;

[0061] (3) The gel is freeze-dried in a freeze dryer at -20 °C for 1 h to obtain an intermediate. Subsequently, the intermediate is calcined under the protection of an oxygen atmosphere. The calcination temperature is 350 °C, the constant temperature is maintained for 6 h, and the heating rate is 3 °C / min. Finally, the calcined product is ground in a high-energy ball mill at a rotation speed of 80 rpm to obtain the NCM613 material.

[0062] Example 4

[0063] This example provides a ternary cathode material, and the preparation method of the ternary cathode material is as follows:

[0064] (1) Weigh 10 g of sodium alginate powder (molecular weight 50,000 - 80,000), add it to 1 L of clear water, heat it in a water bath at 50 °C and supplement it with mechanical stirring to dissolve the sodium alginate powder to form a solution. Weigh 52.34 g of nickel nitrate hexahydrate, 8.73 g of cobalt nitrate hexahydrate, and 25.83 g of manganese nitrate hexahydrate and add them to the container. Stir evenly and add 42.89 g of lithium sulfate to obtain a mixed solution;

[0065] (2) The sodium alginate solution is pumped through a peristaltic pump and delivered to the spray nozzle with a diameter of 150 μm. A vibration with a frequency of 300 Hz is applied at the spray nozzle to eject the sodium alginate in the form of tiny droplets. The droplets at the spray nozzle fall into the mixed solution, and continuous magnetic stirring is supplemented with a stirring speed of 60 rpm. After the reaction is completed, the supernatant liquid in the container is poured off, and the bottom gel is separated by filtration and washed with deionized water;

[0066] (3) The gel is freeze-dried in a freeze dryer at -20 °C for 1 h to obtain an intermediate. Subsequently, the intermediate is calcined under the protection of an oxygen atmosphere. The calcination temperature is 350 °C, the constant temperature is maintained for 6 h, and the heating rate is 3 °C / min. Finally, the calcined product is ground in a high-energy ball mill at a rotation speed of 80 rpm to obtain the NCM613 material.

[0067] Example 5

[0068] The difference between this example and Example 1 is only that the mass ratio of sodium alginate to the solvent is 1:50, and other conditions and parameters are exactly the same as those in Example 1.

[0069] Example 6

[0070] The difference between this example and Example 1 is only that the mass ratio of sodium alginate to the solvent is 1:150, and other conditions and parameters are exactly the same as those in Example 1.

[0071] Example 7

[0072] The difference between this example and Example 1 is only that the calcination temperature is 250 °C, and other conditions and parameters are exactly the same as those in Example 1.

[0073] Example 8

[0074] The difference between this example and Example 1 is only that the calcination temperature is 450 °C, and other conditions and parameters are exactly the same as those in Example 1.

[0075] Comparative Example 1

[0076] This comparative example uses the conventional co-precipitation-high temperature solid-phase sintering method to prepare NCM811 material, including:

[0077] (1) Weigh 69.79 g of nickel nitrate hexahydrate, 8.73 g of cobalt nitrate hexahydrate, and 8.61 g of manganese nitrate hexahydrate, and add them together to 1 L of deionized water. Stir to dissolve all three to obtain a mixed metal salt solution. Subsequently, weigh 10 g of sodium hydroxide powder and add it to the aforementioned mixed metal solution. Dropwise add 4 mol / L ammonia water solution to adjust the solution pH = 11. Continuously stir and react for 10 h, with a stirring speed of 800 r / min, and maintain the reaction temperature at a constant 60 °C. After the reaction is completed, the product is filtered, washed with water, and dried to obtain the NCM811 precursor;

[0078] (2) After uniformly premixing the precursor and lithium hydroxide powder in a high-speed mixer, calcine it in an oxygen atmosphere at 700 °C for 6 h to obtain the NCM811 material.

[0079] Comparative Example 2

[0080] This comparative example uses the conventional co-precipitation-high temperature solid-phase sintering method to prepare NCM613 material. The specific operation is only different from that of Comparative Example 1 in that the mass of nickel nitrate hexahydrate is 52.34 g, the mass of cobalt nitrate hexahydrate is 8.73 g, the mass of manganese nitrate hexahydrate is 25.83 g, and the calcination temperature is 800 °C.

[0081] Comparative Example 3

[0082] The difference between this comparative example and Example 1 is only that the freeze-drying treatment is replaced with a conventional drying treatment, and other conditions and parameters are exactly the same as those in Example 1.

[0083] Comparative Example 4

[0084] The difference between this comparative example and Example 1 is only that sodium alginate is replaced with sodium gluconate, and other conditions and parameters are exactly the same as those in Example 1.

[0085] Performance test:

[0086] The ternary cathode materials, conductive agents, and binders prepared in the examples and comparative examples were uniformly mixed and then coated on an aluminum foil current collector. After drying, rolling, and slitting, the positive electrode sheets were obtained. Subsequently, the positive electrode sheets, lithium sheets, separators, and electrolyte LiPF6 were assembled into coin cells. The initial discharge specific capacity at 0.1C and the capacity retention rate after 50 cycles at 1C were tested on a BlueTEC electrochemical workstation. The test results are shown in Table 1:

[0087] Table 1

[0088]

[0089]

[0090] As can be seen from Table 1, it can be obtained from Examples 1-4 that the initial discharge specific capacity at 0.1C of the NCM811 ternary cathode material prepared by the method of the present invention can reach more than 215.8 mAh / g, and the capacity retention rate after 50 cycles can reach more than 96.5%. The initial discharge specific capacity at 0.1C of the NCM613 ternary cathode material can reach more than 190.2 mAh / g, and the capacity retention rate after 50 cycles can reach more than 97.3%. Using lithium chloride or lithium sulfate as the lithium source can also obtain ternary cathode materials with good performance.

[0091] By comparing Example 1 with Examples 5-6, it can be obtained that during the preparation process of the ternary cathode material of the present invention, the concentration of the sodium alginate solution will affect the performance of the prepared cathode material. Controlling the mass ratio of sodium alginate to the solvent at 1:(80-120) can obtain better performance of the prepared cathode material. If the concentration of the sodium alginate solution is too high, it will cause the liquid flow to be difficult to fully disperse into droplets, resulting in larger gel particles, larger final product particles, smaller specific surface area, decreased reaction activity, and deterioration of both the specific capacity and the capacity retention rate. If the concentration of the sodium alginate solution is too low, the chelation reaction will not proceed sufficiently, the binding degree between lithium and transition metals will decrease, and the specific capacity and the capacity retention rate will also decrease.

[0092] By comparing Example 1 with Examples 7-8, it can be obtained that during the preparation process of the ternary cathode material of the present invention, the calcination temperature will affect the performance of the prepared cathode material. Controlling the calcination temperature at 300-400°C can obtain better performance of the prepared cathode material. If the calcination temperature is too high, the particles will agglomerate, resulting in a decrease in the active area and a decrease in both the specific capacity and the capacity retention rate. If the calcination temperature is too low, the particles will not develop completely, and it is also difficult to maintain the specific capacity and the capacity retention rate.

[0093] It can be obtained by comparing Example 1 with Comparative Example 1, and Example 3 with Comparative Example 2 that during the traditional high-temperature solid-phase sintering process, a very high energy is required for lithium to diffuse into the metal phase, resulting in high energy consumption. In the gel method of the present invention, the energy required for the combination of lithium and transition metals is greatly reduced by using chemical driving force, thus reducing energy consumption and production costs.

[0094] It can be obtained by comparing Example 1 with Comparative Example 3 that the present invention obtains an intermediate by freeze-drying the gel to remove moisture. Freeze-drying can maintain structural stability and maximize the product consistency.

[0095] It can be obtained by comparing Example 1 with Comparative Example 4 that the present invention uses sodium alginate as a chelating agent to form a composite gel of a lithium source and transition metal ions. This process greatly reduces energy consumption and production costs compared with the traditional high-temperature solid-phase sintering method.

[0096] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of within the technical scope disclosed by the present invention by those skilled in the art all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A preparation method of a ternary cathode material, characterized in that The preparation method includes the following steps: (1) Atomize the sodium alginate solution. After mixing a nickel source, a cobalt source, and a manganese source with a solvent, add a lithium source to obtain a mixed solution. The mass ratio of sodium alginate to the solvent in the sodium alginate solution is 1:(80 - 120); (2) Spray the atomized sodium alginate solution into the mixed solution for reaction. After the reaction, perform solid-liquid separation to obtain a gel. Stirring is carried out while spraying in step (2), and the stirring speed is 50 - 70 rpm; (3) Perform freeze-drying treatment on the gel to obtain an intermediate, and perform calcination treatment on the intermediate to obtain the ternary cathode material; The temperature of the freeze-drying treatment in step (3) is -30 to -15°C; the temperature of the calcination treatment is 300 to 400°C, and the time of the calcination treatment is 4 to 8 h.

2. The preparation method according to claim 1, wherein The molecular weight of the sodium alginate in step (1) is 50000 - 80000.

3. The preparation method according to claim 1, characterized in that, The temperature of the mixing is 40 - 60°C.

4. The preparation method according to claim 1, characterized in that, The atomization treatment in step (1) includes pumping the sodium alginate solution through a peristaltic pump to a spray port, and applying vibration at the spray port to eject the sodium alginate in the form of tiny droplets.

5. The preparation method according to claim 4, wherein The diameter of the spray port is 120 - 180 μm.

6. The preparation method according to claim 4, characterized in that, The frequency of the vibration is 200 - 400 Hz.

7. The preparation method according to claim 1, characterized in that, The nickel source in step (1) includes any one or a combination of at least two of nickel chloride, nickel sulfate, or nickel nitrate.

8. The preparation method according to claim 1, characterized in that, The manganese source includes any one or a combination of at least two of nickel chloride, manganese sulfate, or manganese nitrate.

9. The preparation method according to claim 1, characterized in that, The cobalt source includes any one or a combination of at least two of cobalt chloride, cobalt sulfate, or cobalt nitrate.

10. The preparation method according to claim 1, wherein The lithium source includes any one or a combination of at least two of lithium hydroxide, lithium chloride, or lithium sulfate.

11. The preparation method according to claim 1, characterized in that, Washing treatment is carried out after the solid-liquid separation.

12. The preparation method according to claim 11, characterized in that, The detergent for the washing treatment includes deionized water.

13. The preparation method according to claim 1, characterized in that, The time of the freeze-drying treatment is 0.8 - 1.2 h.

14. The preparation method according to claim 1, characterized in that, The atmosphere of the calcination treatment in step (3) includes an oxygen atmosphere.

15. The preparation method according to claim 1, characterized in that, Grinding treatment is carried out after the calcination treatment.

16. The preparation method according to claim 15, wherein, The speed of the grinding treatment is 60 - 100 rpm.

17. A ternary cathode material, characterized in that, The ternary cathode material is prepared by the method according to any one of claims 1 - 16.

18. A positive electrode sheet, characterized in that, The positive electrode sheet includes the ternary cathode material according to claim 17.

19. A lithium-ion battery, characterized in that, The lithium-ion battery includes the positive electrode sheet according to claim 18.

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