Coated modified ternary positive electrode material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of battery electrodes, and particularly relates to a coated modified ternary positive electrode material as well as a preparation method and application thereof. The invention provides a coating modified ternary positive electrode material. The coating modified ternary positive electrode material comprises a ternary positive electrode material and a high-entropy metal coating layer coating the surface of the ternary positive electrode material, the metal elements in the high-entropy metal coating layer comprise Li, Al and Ti; the metal elements in the high-entropy metal coating layer further comprise at least one of Mg, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Sn, Ta and W. The coated modified ternary positive electrode material provided by the invention is excellent in specific capacity, first effect and cycle stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery electrodes, and particularly relates to a coated and modified ternary cathode material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of the electric vehicle and energy storage fields, higher requirements are put forward for the energy density, cycle life, and safety performance of lithium-ion batteries. High-nickel ternary cathode materials (LiN x Co y Mn z O2, x + y + z = 1, x ≥ 0.9) have become strong competitors for the cathode materials of next-generation high-energy-density lithium-ion batteries due to their high specific capacity and relatively low cost.

[0003] However, high-nickel ternary materials also have some inherent defects. For example, during the charge and discharge process of high-nickel ternary cathode materials, the surface is prone to side reactions with the electrolyte, generating an unstable interfacial layer (such as L2CO3, LiF, etc.). These side reactions will cause the surface structure of the material to degrade, resulting in irreversible phase changes (such as the transformation from a layered structure to a spinel structure), and releasing oxygen, reducing the safety performance and cycle life of the battery; there are large volume changes during the charge and discharge process of high-nickel materials (such as the insertion and extraction of Li + lead to lattice expansion and contraction), and this volume change will cause stress and cracks to occur inside the particles. The generation of particle fragmentation and cracks will accelerate the penetration of the electrolyte into the material interior, further exacerbating the side reactions, resulting in specific capacity attenuation, decline in initial efficiency, and cycle stability performance. It can be seen that the specific capacity and initial efficiency of existing high-nickel ternary cathode materials still need to be improved, and the cycle stability performance is poor. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects that the specific capacity and initial efficiency of existing high-nickel ternary cathode materials still need to be improved, and the cycle stability performance is poor, so as to provide a coated and modified ternary cathode material, a preparation method thereof, and an application thereof.

[0005] The present invention provides a coated and modified ternary cathode material, which includes a ternary cathode material and a high-entropy metal coating layer coated on the surface of the ternary cathode material;

[0006] The metal elements in the high-entropy metal coating layer include Li, Al, and Ti;

[0007] The metal elements in the high-entropy metal coating layer further include at least one of Mg, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Sn, Ta, and W.

[0008] The chemical general formula of the ternary cathode material is LiNix Co y Mn z O₂, where x + y + z = 1 and x ≥ 0.9.

[0009] The present invention provides a method for preparing the coated and modified ternary cathode material described above, comprising the following steps:

[0010] 1) Mix the ternary cathode material and a solvent to form a suspension;

[0011] 2) Add at least four metal salt solutions to the suspension obtained in step 1) and mix, then add a precipitating agent for coprecipitation reaction to obtain a high-entropy coating precursor;

[0012] The at least four metal salt solutions include a salt solution of Li, a salt solution of Al, a salt solution of Ti, and a salt solution of at least one other metal;

[0013] 3) Heat-treat the high-entropy coating precursor obtained in step 2) to obtain the coated and modified ternary cathode material.

[0014] Preferably, the chemical general formula of the ternary cathode material in step 1) is LiNi x Co y Mn z O₂, where x + y + z = 1 and x ≥ 0.9.

[0015] Preferably, the solvent in step 1) is selected from at least one of water, ethanol, and isopropanol;

[0016] The concentration of the ternary cathode material in the suspension is 0.08 - 0.12 g / mL.

[0017] Preferably, the mass concentration of the metal salt in the metal salt solution in step 2) is 0.05 - 0.2 mol / L;

[0018] The salt solution of the other metal in step 2) includes at least one of a salt solution of Mg, a salt solution of V, a salt solution of Cr, a salt solution of Mn, a salt solution of Fe, a salt solution of Co, a salt solution of Ni, a salt solution of Cu, a salt solution of Zn, a salt solution of Zr, a salt solution of Nb, a salt solution of Mo, a salt solution of Sn, a salt solution of Ta, a salt solution of W, and a zirconium oxy-salt solution.

[0019] In step 2) of the present invention, when adding at least four metal salt solutions, the number of the added metal salt solutions is not specifically limited. For example, optionally, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18 metal salt solutions can be added. Optionally, the volume ratio of each added metal salt solution to the volume of the Li salt solution is (0.9 - 1.2):(0.9 - 1.2).

[0020] Preferably, in step 2), when adding four metal salt solutions to the suspension in step 1) for mixing, the volume ratio of the four metal salt solutions is (0.9 - 1.2):(0.9 - 1.2):(0.9 - 1.2):(0.9 - 1.2);

[0021] In step 2), when adding five metal salt solutions to the suspension in step 1) for mixing, the volume ratio of the five metal salt solutions is (0.9 - 1.2):(0.9 - 1.2):(0.9 - 1.2):(0.9 - 1.2):(0.9 - 1.2);

[0022] In step 2), when adding six metal salt solutions to the suspension in step 1) for mixing, the volume ratio of the six metal salt solutions is (0.9 - 1.2):(0.9 - 1.2):(0.9 - 1.2):(0.9 - 1.2):(0.9 - 1.2):(0.9 - 1.2);

[0023] In step 2), the volume ratio of the total volume of the at least four added metal salt solutions to the volume of the suspension is (15 - 25):(95 - 110).

[0024] Preferably, the precipitant in step 2) is selected from at least one of NaOH solution, Na2S solution, and KOH solution;

[0025] The concentration of the solute in the precipitant is 0.9 - 1.2 mol / L;

[0026] In step 2), the pH value of the co - precipitation reaction solution is controlled to be 7 - 9 by adding the precipitant, and the co - precipitation reaction time is 1.5 - 3 h.

[0027] Preferably, the heat treatment temperature in step 3) is 400 - 500 °C and the heat treatment time is 4 - 5 h;

[0028] Optionally, before the heat treatment step in step 3), there are also steps of washing and drying the above - mentioned high - entropy coating precursor.

[0029] Preferably, the chemical general formula of the ternary cathode material in step 1) is LiNi x Co y Mnz O2, where x + y + z = 1 and x ≥ 0.9.

[0030] Preferably, the metal salt solution in step 2) is selected from at least one of metal nitrate solutions, metal chloride solutions, metal sulfate solutions, metal carbonate solutions, and metal acetate solutions;

[0031] Preferably, the salt solution of Li in step 2) is selected from at least one of LiNO3 solution and LiCl solution;

[0032] The salt solution of Al in step 2) is selected from at least one of Al(NO3)3 solution and AlCl3 solution;

[0033] The salt solution of Ti in step 2) is selected from at least one of Ti(SO4)2 solution, TiCl4 solution, and K2TiF6 solution;

[0034] The salt solution of other metals in step 2) is selected from at least one of ZrO(NO3)2 solution, MgCl2 solution, Mg(NO3)2 solution, VCl3 solution, VCl4 solution, CrCl3 solution, Cr(CH3COO)3 solution, MnCl2 solution, FeCl2 solution, FeCl3 solution, CoCl2 solution, CoSO4 solution, Co(NO3)2 solution, NiCl2 solution, Ni(NO3)2 solution, CuCl solution, Cu(NO3)2 solution, ZnCl2 solution, Zr(NO3)4 solution, NbCl5 solution, and SnCl2 solution.

[0035] The present invention also provides an application of the coated and modified ternary cathode material in a lithium-ion battery.

[0036] The technical solution of the present invention has the following advantages:

[0037] 1. The coated and modified ternary cathode material provided by the present invention, the coated and modified ternary cathode material includes a ternary cathode material and a high-entropy metal coating layer coated on the surface of the ternary cathode material; the metal elements in the high-entropy metal coating layer include Li, Al, and Ti; the metal elements in the high-entropy metal coating layer further include at least one of Mg, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Sn, Ta, and W. The chemical general formula of the ternary cathode material is LiNi x Co y Mn zO2, where x + y + z = 1 and x ≥ 0.9. The Li element and Ti element can improve the ionic conductivity of the material, and the Al element can improve the structural stability of the material. In the present invention, the coating layer simultaneously includes the Li element, Ti element, and Al element. The coating layers of Al and Ti can reduce the dissolution of transition metal ions (such as Ni 3 +, Co3+), and the introduction of Li further passivates the surface. The three elements jointly inhibit the decomposition of the electrolyte and side reactions, improving the stability of the cathode material under high temperature and high pressure, thereby comprehensively and synergistically improving the electrochemical performance of the material, especially increasing the specific capacity, initial efficiency, and cycle stability of the ternary cathode material.

[0038] 2. The preparation method of the coated and modified ternary cathode material provided by the present invention includes the following steps: 1) Mix the ternary cathode material and a solvent to form a suspension; 2) Add at least four metal salt solutions to the suspension obtained in step 1) and mix them, then add a precipitating agent for coprecipitation reaction to obtain a high-entropy coating layer precursor; the at least four metal salt solutions include a salt solution of Li, a salt solution of Al, a salt solution of Ti, and a salt solution of at least one other metal; 3) Heat-treat the high-entropy coating layer precursor obtained in step 2) to obtain the coated and modified ternary cathode material. The coating layer formed by the preparation method of the present invention is an amorphous structure, which can better adapt to the volume change of the cathode material during charge and discharge, reduce particle breakage and crack generation, and further improve the specific capacity, initial efficiency, and cycle stability of the material.

[0039] 3. The preparation method of the coated and modified ternary cathode material provided by the present invention has a simple process and is easy to realize industrial production. Detailed Embodiments

[0040] The following embodiments are provided to better understand the present invention further. They are not limited to the best embodiment, and do not limit the content and protection scope of the present invention. Any product obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with those of other prior arts and being the same as or similar to the present invention falls within the protection scope of the present invention.

[0041] For those not specifying specific experimental steps or conditions in the embodiments, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For reagents or instruments without indicating the manufacturer, they are all conventional reagent products that can be obtained through commercial purchase.

[0042] Example 1

[0043] This example provides a preparation method of a coated and modified ternary cathode material, including the following steps:

[0044] 1) Take 10 g of LiNi 0.9 Co0.06 Mn 0.04 Mix the MnO₂ ternary cathode material with 100 mL of water to form a suspension;

[0045] 2) Add 0.1 mol / L LiNO₃ solution, 0.1 mol / L Al(NO₃)₃ solution, 0.1 mol / L Ti(SO₄)₂ solution, and 0.1 mol / L ZrO(NO₃)₂ solution with a volume ratio of 1:1:1:1 to the suspension in step 1). The total volume of the LiNO₃ solution, Al(NO₃)₃ solution, Ti(SO₄)₂ solution, and ZrO(NO₃)₂ solution is in a volume ratio of 20:100 to the volume of the suspension. Then add 1 mol / L NaOH solution to control the pH value of the mixed reaction solution to 9 for coprecipitation reaction. The coprecipitation reaction time is 2 h, and filter to obtain the high-entropy coating precursor;

[0046] 3) Wash and dry the high-entropy coating precursor obtained in step 2), and then calcine it at 500 °C for 5 h to obtain the coated and modified ternary cathode material.

[0047] Example 2

[0048] This example provides a preparation method of a coated and modified ternary cathode material, including the following steps:

[0049] 1) Mix 10 g of LiNi 0.9 Co 0.06 Mn 0.04 O₂ ternary cathode material with 100 mL of water to form a suspension;

[0050] 2) Add 0.1 mol / L LiCl solution, 0.1 mol / L MgCl₂ solution, 0.1 mol / L AlCl₃ solution, and 0.1 mol / L TiCl₄ solution with a volume ratio of 1:1:1:1 to the suspension in step 1). The total volume of the LiNO₃ solution, Al(NO₃)₃ solution, Ti(SO₄)₂ solution, and ZrO(NO₃)₂ solution is in a volume ratio of 20:100 to the volume of the suspension. Then add 1 mol / L Na₂S solution to control the pH value of the coprecipitation reaction solution to 7 for coprecipitation reaction. The coprecipitation reaction time is 2 h, and filter to obtain the high-entropy coating precursor;

[0051] 3) Wash and dry the high-entropy coating precursor obtained in step 2), and then calcine it at 400 °C for 5 h to obtain the coated and modified ternary cathode material.

[0052] Example 3

[0053] This example provides a preparation method of a coated and modified ternary cathode material, including the following steps:

[0054] 1) Mix 12 g of LiNi 0.9 Co 0.06 Mn 0.04 O2 ternary cathode material with 100 mL of water to form a suspension;

[0055] 2) Add 0.15 mol / L LiNO3 solution, 0.15 mol / L Al(NO3)3 solution, 0.15 mol / L Ti(SO4)2 solution, and 0.15 mol / L ZrO(NO3)2 solution with a volume ratio of 1:1:1:1 to the suspension in step 1). The total volume of the LiNO3 solution, Al(NO3)3 solution, Ti(SO4)2 solution, and ZrO(NO3)2 solution is in a volume ratio of 15:95 to the volume of the suspension. Then add 0.9 mol / L NaOH solution to control the pH value of the mixed reaction solution to 8 for coprecipitation reaction. The coprecipitation reaction time is 3 h, and filter to obtain the high-entropy coating precursor;

[0056] 3) Wash and dry the high-entropy coating precursor obtained in step 2), and then calcine it at 450 °C for 4.5 h to obtain the coated and modified ternary cathode material.

[0057] Example 4

[0058] This example provides a preparation method for a coated and modified ternary cathode material, including the following steps:

[0059] 1) Mix 10 g of LiNi 0.9 Co 0.06 Mn 0.04 O2 ternary cathode material with 110 mL of water to form a suspension;

[0060] 2) Add 0.1 mol / L LiNO3 solution, 0.1 mol / L Al(NO3)3 solution, 0.1 mol / L Ti(SO4)2 solution, and 0.1 mol / L ZrO(NO3)2 solution with a volume ratio of 1:1:1:1 to the suspension in step 1). The total volume of the LiNO3 solution, Al(NO3)3 solution, Ti(SO4)2 solution, and ZrO(NO3)2 solution is in a volume ratio of 25:110 to the volume of the suspension. Then add 1.2 mol / L NaOH solution to control the pH value of the mixed reaction solution to 7 for coprecipitation reaction. The coprecipitation reaction time is 1.5 h, and filter to obtain the high-entropy coating precursor;

[0061] 3) Wash and dry the high-entropy coating precursor obtained in step 2), and then calcine it at 500 °C for 4 h to obtain the coated and modified ternary cathode material.

[0062] Comparative Example 1

[0063] This comparative example provides a method for preparing a modified ternary cathode material, which includes the following steps:

[0064] 1) Mix 10 g of LiNi 0.9 Co 0.06 Mn 0.04 O2 ternary cathode material with 100 mL of water to form a suspension;

[0065] 3) Filter the suspension obtained in step 1), wash and dry the solid ternary cathode material obtained by filtration, and then calcine it at 500 °C for 5 h to obtain the modified ternary cathode material.

[0066] Comparative Example 2

[0067] This comparative example provides a method for preparing a coated modified ternary cathode material, which is different from Example 1 in that in step 2), a 0.1 mol / L Zn(NO3)2 solution, a 0.1 mol / L CoSO4 solution, and a 0.1 mol / L ZrO(NO3)2 solution with a volume ratio of 1:1:1 are added to the suspension obtained in step 1). The total volume of the Zn(NO3)2 solution, the CoSO4 solution, and the ZrO(NO3)2 solution and the volume of the suspension are in a ratio of 20:100. Then, a 1 mol / L NaOH solution is added to control the pH value of the mixed reaction solution to 9 for coprecipitation reaction. The coprecipitation reaction time is 2 h, and a high-entropy coating precursor is obtained by filtration;

[0068] 3) Wash and dry the high-entropy coating precursor obtained in step 2), and then calcine it at 500 °C for 5 h to obtain the coated modified ternary cathode material.

[0069] Comparative Example 3

[0070] This comparative example provides a method for preparing a coated modified ternary cathode material, which is different from Example 1 in that in step 2), a 0.1 mol / L Al(NO3)3 solution, a 0.1 mol / L Ti(SO4)2 solution, and a 0.1 mol / L ZrO(NO3)2 solution with a volume ratio of 1:1:1 are added to the suspension obtained in step 1). The total volume of the Al(NO3)3 solution, the Ti(SO4)2 solution, and the ZrO(NO3)2 solution and the volume of the suspension are in a ratio of 20:100. Then, a 1 mol / L NaOH solution is added to control the pH value of the mixed reaction solution to 9 for coprecipitation reaction. The coprecipitation reaction time is 2 h, and a high-entropy coating precursor is obtained by filtration;

[0071] 3) Wash and dry the high-entropy coating precursor obtained in step 2), and then calcine it at 500 °C for 5 h to obtain the coated modified ternary cathode material.

[0072] Comparative Example 4

[0073] This comparative example provides a preparation method for a coated and modified ternary cathode material. The difference from Example 1 is only that in step 2), a 0.1 mol / L LiNO3 solution, a 0.1 mol / L Ti(SO4)2 solution, and a 0.1 mol / L ZrO(NO3)2 solution with a volume ratio of 1:1:1 are added to the suspension in step 1). The total volume of the LiNO3 solution, the Ti(SO4)2 solution, and the ZrO(NO3)2 solution and the volume of the suspension are in a ratio of 20:100. Then, a 1 mol / L NaOH solution is added to control the pH value of the mixed reaction solution to 9 for coprecipitation reaction. The coprecipitation reaction time is 2 h, and the high-entropy coating precursor is obtained by filtration.

[0074] Comparative Example 5

[0075] This comparative example provides a preparation method for a coated and modified ternary cathode material. The difference from Example 1 is only that in step 2), a 0.1 mol / L LiNO3 solution, a 0.1 mol / L Al(NO3)3 solution, and a 0.1 mol / L ZrO(NO3)2 solution with a volume ratio of 1:1:1 are added to the suspension in step 1). The total volume of the LiNO3 solution, the Al(NO3)3 solution, and the ZrO(NO3)2 solution and the volume of the suspension are in a ratio of 20:100. Then, a 1 mol / L NaOH solution is added to control the pH value of the mixed reaction solution to 9 for coprecipitation reaction. The coprecipitation reaction time is 2 h, and the high-entropy coating precursor is obtained by filtration.

[0076] Test Example

[0077] The ternary cathode materials prepared in Examples 1-4 and Comparative Examples 1-5 were respectively used as the main materials to assemble lithium-ion batteries. The specific steps were as follows: Prepare the positive electrode sheet. Using N-methylpyrrolidone as a dispersant, the main material: carbon black: PVDF (polyvinylidene fluoride) was mixed with the dispersant according to a mass ratio of 90:5:5 to prepare the positive electrode slurry respectively. The positive electrode slurry was uniformly coated on the carbon-coated aluminum foil, and the coating surface density was 12 cm 2 / mg, dried in an oven at 80 °C for 2 h to obtain the positive electrode sheet respectively; in an argon atmosphere in a glove box, a Celgard 2500 type separator, a lithium metal sheet as the negative electrode sheet, and a 1 mol / L LiPF6 ethylene carbonate (EC) / dimethyl carbonate (DMC) / ethyl methyl carbonate (EMC) (volume ratio 1:1:0.5) solution as the electrolyte were used; a CR2032 type button half-cell was assembled in the order of the negative electrode sheet, the electrolyte, the separator, the electrolyte, and the positive electrode sheet.

[0078] At 25 °C, charge at a rate of 0.2C to 4.25V, and then discharge at a rate of 0.2C to 2.5V. This is a cycle process. The charge-discharge capacity this time is the initial charge-discharge specific capacity. The initial discharge specific capacity / the initial charge specific capacity * 100% is the initial efficiency. After 2 cycles, charge at 1C and discharge at 1C for 50 cycles. Record the charge-discharge capacity of the 3rd cycle and the charge-discharge capacity of the 52nd cycle. The cycle retention rate is the ratio of the discharge capacity of the 52nd cycle to that of the 3rd cycle. The test results of the initial discharge specific capacity, the initial efficiency, and the cycle retention rate are shown in Table 1.

[0079] Table 1

[0080]

[0081] The electrochemical performance test results in Table 1 show that the initial discharge specific capacities of the cathode materials prepared in Example 1 and Example 2 at a rate of 0.2C are 223.1 mAh / g and 220.1 mAh / g respectively, both higher than 200.1 mAh / g of Comparative Example 1. After 50 cycles at a rate of 1C, the capacity retention rates of the cathode materials prepared in Example 1 and Example 2 are 96.9% and 96.4% respectively, both higher than 80.8% of Comparative Example 1.

[0082] The above results show that the high-nickel ternary cathode material modified with a high-entropy coating layer provided by the present invention has a high specific capacity, an initial efficiency, and excellent cycle stability.

[0083] Obviously, the above examples are only for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A coated modified ternary positive electrode material, characterized in that: The coated modified ternary positive electrode material comprises a ternary positive electrode material and a high entropy metal coating layer coated on the surface of the ternary positive electrode material; The metal elements in the high entropy metal coating layer include Li, Al, and Ti; The metal element in the high entropy metal coating layer also includes at least one of Mg, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Sn, Ta, and W; The chemical formula of the ternary cathode material is LiNi x Co y Mn z O2, where x+y+z=1, x≥0.

9.

2. A method for preparing the coated modified ternary positive electrode material according to claim 1, characterized in that: The following steps are involved: 1) Mixing the ternary cathode material and the solvent to form a suspension; 2) adding at least four metal salt solutions to the suspension of step 1) and mixing, and then adding a precipitant to perform a co-precipitation reaction to obtain a high entropy coating layer precursor; The at least four metal salt solutions include a Li salt solution, an Al salt solution, a Ti salt solution and a salt solution of at least one other metal; 3) heat-treating the high entropy coating layer precursor obtained in step 2) to obtain the coated modified ternary positive electrode material.

3. The method for preparing the coated modified ternary positive electrode material according to claim 2, characterized in that: The solvent in step 1) is selected from at least one of water, ethanol and isopropanol; The concentration of the ternary positive electrode material in the suspension is 0.08-0.12 g / mL.

4. The method for preparing the coated modified ternary positive electrode material according to claim 2 or 3, characterized in that: The mass concentration of the metal salt in the metal salt solution in step 2) is 0.05-0.2 mol / L; The salt solutions of other metals described in step 2) include at least one of Mg salt solutions, V salt solutions, Cr salt solutions, Mn salt solutions, Fe salt solutions, Co salt solutions, Ni salt solutions, Cu salt solutions, Zn salt solutions, Zr salt solutions, Nb salt solutions, Mo salt solutions, Sn salt solutions, Ta salt solutions, W salt solutions, and zirconium oxide salt solutions.

5. The method for preparing the coated modified ternary positive electrode material according to any one of claims 2 to 4, characterized in that: In step 2), when four metal salt solutions are added to the suspension of step 1) for mixing, the volume ratio of the four metal salt solutions is (0.9-1.2): (0.9-1.2): (0.9-1.2): (0.9-1.2); In step 2), when five metal salt solutions are added to the suspension of step 1) for mixing, the volume ratio of the five metal salt solutions is (0.9-1.2): (0.9-1.2): (0.9-1.2): (0.9-1.2): (0.9-1.2); In step 2), when six metal salt solutions are added to the suspension of step 1) for mixing, the volume ratio of the six metal salt solutions is (0.9-1.2): (0.9-1.2): (0.9-1.2): (0.9-1.2): (0.9-1.2): (0.9-1.2); In step 2), the volume ratio of the total volume of at least four metal salt solutions added to the suspension is (15-25):(95-110).

6. The method for preparing the coated modified ternary positive electrode material according to any one of claims 2 to 5, characterized in that: The precipitant in step 2) is selected from at least one of NaOH solution, Na2S solution and KOH solution; The concentration of the solute in the precipitant is 0.9-1.2 mol / L; In step 2), the pH value of the coprecipitation reaction solution is controlled to be 7-9 by adding a precipitant, and the coprecipitation reaction time is 1.5-3h.

7. The method for preparing the coated modified ternary positive electrode material according to any one of claims 2 to 6, characterized in that: The heat treatment temperature in step 3) is 400-500°C and the heat treatment time is 4-5h; Optionally, the heat treatment step in step 3) further includes the steps of washing and drying the high entropy coating layer precursor.

8. The method for preparing the coated modified ternary positive electrode material according to any one of claims 2 to 7, characterized in that: The chemical formula of the ternary cathode material in step 1) is LiNi x Co y Mn z O2, where x+y+z=1, x≥0.

9.

9. The method for preparing the coated modified ternary positive electrode material according to any one of claims 2 to 8, characterized in that: The metal salt solution in step 2) is selected from at least one of a metal nitrate solution, a metal chloride solution, a metal sulfate solution, a metal carbonate solution, and a metal acetate solution; Preferably, the Li salt solution in step 2) is selected from at least one of a LiNO3 solution and a LiCl solution; The Al salt solution in step 2) is selected from at least one of Al(NO3)3 solution and AlCl3 solution; The Ti salt solution in step 2) is selected from at least one of Ti(SO4)2 solution, TiCl4 solution, and K2TiF6 solution; The salt solution of other metals described in step 2) is selected from at least one of ZrO(NO3)2 solution, MgCl2 solution, Mg(NO3)2 solution, VCl3 solution, VCl4 solution, CrCl3 solution, Cr(CH3COO)3 solution, MnCl2 solution, FeCl2 solution, FeCl3 solution, CoCl2 solution, CoSO4 solution, Co(NO3)2 solution, NiCl2 solution, Ni(NO3)2 solution, CuCl solution, Cu(NO3)2 solution, ZnCl2 solution, Zr(NO3)4 solution, NbCl5 solution, and SnCl2 solution.

10. Use of the coated modified ternary positive electrode material according to claim 1 or the coated modified ternary positive electrode material prepared by the preparation method according to any one of claims 2 to 9 in lithium ion batteries.

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