Double-metal gradient diffusion layer modified high-nickel ternary positive electrode material and preparation method thereof

Abstract

The invention discloses a double-metal gradient diffusion layer modified high-nickel ternary positive electrode material and a preparation method thereof. The preparation method comprises the following steps: filtering and uniformly dispersing high-nickel ternary positive electrode material powder; introducing inert gas into the atomic layer deposition system, and raising the temperature to a target temperature; respectively preheating the metal precursors A and B to proper temperatures; the preparation method comprises the following steps: sequentially introducing a metal precursor A, precursor water, a metal precursor B and precursor water into a reaction chamber, alternately depositing according to a pulse-reaction-purging sequence, and repeatedly circulating the process to obtain the bimetallic oxide coated high-nickel ternary positive electrode material, and post-annealing treatment. According to the bimetal gradient diffusion layer modified high-nickel ternary positive electrode material prepared by the preparation method disclosed by the invention, the lithium storage performance of the high-nickel ternary material is greatly improved, excellent cycling stability and rate capability are obtained, the coating layer is accurate and controllable, the preparation process is simple, meanwhile, large-batch production can be realized, and relatively high application value is achieved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery cathode material technology, specifically relating to a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry and the continuous increase in the energy density requirements of energy storage systems, high-nickel ternary layered oxides have become a key research direction for next-generation lithium-ion battery cathode materials due to their high theoretical specific capacity and energy density. However, problems such as interface structure degradation, transition metal ion dissolution, lattice oxygen precipitation, and microcracks caused by the H2-H3 phase transition during cycling of high-nickel materials make it difficult for their actual cycle life and rate performance to meet commercialization requirements.

[0003] Current mainstream surface coating technologies face multiple bottlenecks: First, the coating thickness is difficult to precisely control—oxide coatings prepared by wet chemical methods (such as sol-gel and liquid phase deposition) often exhibit thickness fluctuations due to uneven reaction kinetics. Excessive thickness significantly hinders lithium-ion diffusion channels, leading to a decrease in material rate performance. Second, there is a limitation in functionality; single metal oxide coatings (such as Al2O3 and TiO2) can only suppress electrolyte interface side reactions to a limited extent, but cannot simultaneously address the problem of bulk structural stress accumulation caused by lattice distortion in high-nickel materials. Third, interfacial bonding is weak; traditional coatings are mostly physically attached to the substrate or weakly chemically bonded, making them prone to interfacial delamination during cycling due to volume expansion, leading to coating failure. Furthermore, existing coating processes struggle to achieve three-dimensional conformal coating, often resulting in coating gaps at secondary particle gaps and grain boundaries, which become preferential channels for electrolyte penetration and transition metal dissolution. These limitations make it difficult for traditional coating technologies to simultaneously meet the requirements of long-cycle stability and high kinetic performance for high-nickel cathodes.

[0004] In recent years, bimetallic synergistic modification strategies have demonstrated unique potential, simultaneously enhancing the mechanical strength and lithium-ion conductivity of surface passivation layers through the complementary valence states and lattice synergistic effects of the two metal elements. However, existing technologies mostly employ physical mixing or co-precipitation methods to introduce bimetals, resulting in uneven element distribution, weak interfacial bonding, and difficulty in constructing depth-controllable gradient diffusion layers through subsequent heat treatment. Furthermore, the high energy consumption and complex preparation process caused by multi-step processes severely restrict their industrial application. Therefore, developing a modification method capable of precisely constructing bimetallic coatings at the atomic scale and achieving gradient doping through a one-step heat treatment has become a key path to overcome the performance bottlenecks of high-nickel ternary materials. Summary of the Invention

[0005] Purpose of the invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer maintains a good layered structure, exhibits high cycle stability and rate performance, high specific capacity, and precise and controllable process.

[0007] Solution

[0008] This invention provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer, characterized in that a nano-coating A of metal oxide A and a nano-coating B of metal oxide B are sequentially applied to the high-nickel ternary cathode material, with coating A and coating B existing alternately, and one coating A and one coating B alternating constitute one repeating cycle, the number of repeating cycles being N, where N is 3-100.

[0009] The total coating thickness after repeated application of nano-coating A of metal oxide A and nano-coating B of metal oxide B is 0.6-20 nm.

[0010] The metal oxide A and metal oxide B are different metal oxides.

[0011] The high-nickel ternary cathode material modified by the bimetallic gradient diffusion layer consists of spherical secondary particles formed by the agglomeration of brick-shaped primary particles, with a diameter of 8-12 micrometers.

[0012] The high-nickel ternary cathode material is LiNi. 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.83 Co 0.12 Mn 0.05 O2, LiNi 0.90 Co 0.05 Mn 0.05 One or more of O2.

[0013] The metal oxide A and metal oxide B are obtained from metal precursor A and metal precursor B, respectively. Metal precursor A and metal precursor B include one or more of lithium tert-butoxide, trimethylaluminum, diethylzinc, titanium tetraisopropoxide, tetra(dimethylamine)hafnium, tetra(dimethylamine)tin, tri(diethylamine)tert-butylamineniobium, ferrocene, tetra(dimethylamino)vanadium, tetra(dimethylamino)zirconium, and tantalum acetate, and metal precursor A and metal precursor B are different.

[0014] The preparation method of the bimetallic gradient diffusion layer modified high-nickel ternary cathode material includes the following steps:

[0015] Step 1: Filter the high-nickel ternary cathode material powder of lithium-ion battery through a sieve, disperse it evenly in the sample tray, and place it in the atomic layer deposition reaction chamber;

[0016] Step 2: Inert gas is introduced into the atomic layer deposition system as a carrier gas, and the temperature is raised to the target deposition temperature;

[0017] Step 3: Preheat metal precursor A and metal precursor B, which are required for the deposition process, respectively;

[0018] Step 4: Metal precursor A, water precursor, metal precursor B, and water precursor are sequentially introduced into the reaction chamber. After each precursor is introduced, it is deposited in the order of pulse-reaction-purge. Metal precursor A-water precursor-metal precursor B-water precursor constitutes one deposition cycle. The number of deposition cycles is N, where N is 3-100. This process is repeated to obtain a high-nickel ternary cathode material coated with bimetallic oxide.

[0019] Step 5: Perform post-annealing treatment on the above-coated high-nickel ternary cathode material to obtain the high-nickel ternary cathode material modified with bimetallic gradient diffusion layer.

[0020] In step 1, the high-nickel ternary cathode material for the lithium-ion battery is LiNi. 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.83 Co 0.12 Mn 0.05 O2, LiNi 0.90 Co 0.05 Mn 0.05 One or more of the O2 materials.

[0021] In step 2, the inert gas is one or more of nitrogen and argon, and the target deposition temperature is set to 150-300℃.

[0022] In step 3, metal precursor A and metal precursor B each include one or more of lithium tert-butoxide, trimethylaluminum, diethylzinc, titanium tetraisopropoxide, tetra(dimethylamine)hafnium, tetra(dimethylamine)tin, tri(diethylamine)tert-butylamineniobium, ferrocene, tetra(dimethylamino)vanadium, tetra(dimethylamino)zirconium, and tantalum acetate, and metal precursor A and metal precursor B are different; the preheating temperatures of metal precursor A and metal precursor B are 30-180℃, respectively.

[0023] In step 4, the pulse time of metal precursor A is 0.1–5 s, the reaction time is 5–30 s, and the purging time is 30–60 s; the pulse time of metal precursor B is 0.1–5 s, the reaction time is 5–30 s, and the purging time is 30–60 s; the pulse time of water precursor is 0.1–5 s, the reaction time is 5–30 s, and the purging time is 30–60 s; and the number of deposition cycles N is 3–40.

[0024] In step 5, the atmosphere used for annealing is one or more of nitrogen, argon, and oxygen, the heating rate is 1-5℃ / min, the annealing temperature is 400-700℃, and the cooling rate is 1-5℃ / min.

[0025] The present invention also provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer prepared by the above method.

[0026] Beneficial effects

[0027] The high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer of the present invention has the following technical effects:

[0028] (1) This invention uses atomic layer deposition technology to precisely control the bimetallic oxide nanocoating, effectively suppressing surface side reactions and transition metal dissolution of the material;

[0029] (2) The present invention combines high-temperature annealing-induced gradient doping of bimetals to improve the structural stability of the material and reduce phase transitions and volume changes during cycling.

[0030] (3) This invention provides a way to obtain high-nickel ternary cathode material for lithium-ion batteries with high stability and excellent rate performance. The deposition process is precise and controllable and can be mass-produced, which has high application value and significance. Attached Figure Description

[0031] Figure 1 This is a scanning electron microscope image of a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer prepared in Example 1 of the present invention;

[0032] Figure 2 This is an X-ray diffraction pattern of a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer prepared in Example 2 of the present invention;

[0033] Figure 3 This is a constant current charge-discharge curve of a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer prepared in Example 2 of the present invention;

[0034] Figure 4 This is a cycle performance diagram of a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer prepared in Example 2 of the present invention.

[0035] Figure 5 The rate performance diagrams are for a high-nickel ternary cathode material prepared in Examples 2, 8 and Comparative Example 1 of this invention. Detailed Implementation

[0036] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The preparation method specifically includes the following steps:

[0039] Step 1, LiNi lithium-ion battery 0.83 Co 0.12 Mn 0.05 O2 cathode material powder is filtered through a sieve, uniformly dispersed in a sample tray, and placed in an atomic layer deposition reaction chamber, where the sieve is 400 mesh.

[0040] Step 2: Nitrogen gas is introduced into the atomic layer deposition system as a carrier gas, and the temperature is raised to 200°C;

[0041] Step 3: Preheat the lithium tert-butoxide and trimethylaluminum precursors required for the deposition process to 180°C and 120°C, respectively.

[0042] Step 4: First, lithium tert-butoxide precursor is introduced into the reaction chamber, with a pulse time of 5.0s, a reaction time of 10s, and a purge time of 60s. Water precursor is introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Then, trimethylaluminum precursor is introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Water precursor is introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. This sequence of alternating deposition is repeated for 5 cycles to obtain a high-nickel ternary cathode material coated with bimetallic oxide.

[0043] Step 5: The modified high-nickel ternary cathode material is subjected to post-annealing treatment in an oxygen atmosphere. The temperature is increased to 600°C at a rate of 5°C / min and held for 3 hours. The temperature is then reduced to room temperature at a rate of 5°C / min to obtain a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer.

[0044] Example 2

[0045] This embodiment provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The preparation method specifically includes the following steps:

[0046] Step 1, LiNi lithium-ion battery 0.83 Co 0.12 Mn 0.05 O2 cathode material powder is filtered through a sieve, uniformly dispersed in a sample tray, and placed in an atomic layer deposition reaction chamber, where the sieve is 400 mesh.

[0047] Step 2: Nitrogen gas is introduced into the atomic layer deposition system as a carrier gas, and the temperature is raised to 200°C;

[0048] Step 3: Preheat the trimethylaluminum and tris(diethylamine)tert-butylamine niobium precursors required for the deposition process to 30°C and 120°C, respectively;

[0049] Step 4: First, trimethylaluminum precursor is introduced into the reaction chamber, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Water precursor is then introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Next, tri(diethylamine)tert-butylamine niobium precursor is introduced, with a pulse time of 1.5s, a reaction time of 10s, and a purge time of 60s. Water precursor is then introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. This sequence of alternating deposition is repeated 15 times to obtain a high-nickel ternary cathode material coated with bimetallic oxide.

[0050] Step 5: The modified high-nickel ternary cathode material is subjected to post-annealing treatment in an oxygen atmosphere. The temperature is increased to 600°C at a rate of 5°C / min and held for 3 hours. The temperature is then reduced to room temperature at a rate of 5°C / min to obtain a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer.

[0051] Example 3

[0052] This embodiment provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The preparation method specifically includes the following steps:

[0053] Step 1, LiNi lithium-ion battery 0.83 Co 0.12 Mn 0.05 O2 cathode material powder is filtered through a sieve, uniformly dispersed in a sample tray, and placed in an atomic layer deposition reaction chamber, where the sieve is 400 mesh.

[0054] Step 2: Nitrogen gas is introduced into the atomic layer deposition system as a carrier gas, and the temperature is raised to 200°C;

[0055] Step 3: Preheat the trimethylaluminum and tetra(dimethylamine)tin precursors required for the deposition process to 30°C and 80°C, respectively;

[0056] Step 4: First, trimethylaluminum precursor is introduced into the reaction chamber, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Water precursor is then introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Next, tetra(dimethylamine)tin precursor is introduced, with a pulse time of 0.5s, a reaction time of 10s, and a purge time of 60s. Water precursor is then introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. This sequence of alternating deposition is repeated 15 times to obtain a high-nickel ternary cathode material coated with bimetallic oxide.

[0057] Step 5: The modified high-nickel ternary cathode material is subjected to post-annealing treatment in an oxygen atmosphere. The temperature is increased to 600°C at a rate of 5°C / min and held for 3 hours. The temperature is then reduced to room temperature at a rate of 5°C / min to obtain a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer.

[0058] Example 4

[0059] This embodiment provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The preparation method specifically includes the following steps:

[0060] Step 1, LiNi lithium-ion battery 0.8 Co 0.1 Mn 0.1 O2 cathode material powder is filtered through a sieve, uniformly dispersed in a sample tray, and placed in an atomic layer deposition reaction chamber, where the sieve is 400 mesh.

[0061] Step 2: Nitrogen gas is introduced into the atomic layer deposition system as a carrier gas, and the temperature is raised to 200°C;

[0062] Step 3: Preheat the diethylzinc and ferrocene precursors required for the deposition process to 30°C and 125°C, respectively;

[0063] Step 4: First, diethylzinc precursor is introduced into the reaction chamber, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Water precursor is then introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Then, ferrocene precursor is introduced, with a pulse time of 1.0s, a reaction time of 10s, and a purge time of 60s. Water precursor is then introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. This sequence of alternating deposition is repeated 20 times to obtain a high-nickel ternary cathode material coated with bimetallic oxide.

[0064] Step 5: The modified high-nickel ternary cathode material is subjected to post-annealing treatment in an oxygen atmosphere. The temperature is increased to 500°C at a rate of 5°C / min and held for 3 hours. The temperature is then reduced to room temperature at a rate of 5°C / min to obtain a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer.

[0065] Example 5

[0066] This embodiment provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The preparation method specifically includes the following steps:

[0067] Step 1, LiNi lithium-ion battery 0.90 Co 0.05 Mn 0.05 O2 cathode material powder is filtered through a sieve, uniformly dispersed in a sample tray, and placed in an atomic layer deposition reaction chamber, where the sieve is 400 mesh.

[0068] Step 2: Nitrogen gas is introduced into the atomic layer deposition system as a carrier gas, and the temperature is raised to 220°C;

[0069] Step 3: Preheat the trimethylaluminum and tetraisopropoxide titanium precursors required for the deposition process to 30°C and 80°C, respectively;

[0070] Step 4: First, trimethylaluminum precursor is introduced into the reaction chamber, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Water precursor is introduced, with a pulse time of 0.1s, a reaction time of 10s, and a purge time of 60s. Then, tetraisopropoxide titanium precursor is introduced, with a pulse time of 1.5s, a reaction time of 10s, and a purge time of 60s. Water precursor is introduced, with a pulse time of 0.1s, a reaction time of 10s, and a purge time of 60s. This sequence of alternating deposition is repeated for 5 cycles to obtain a high-nickel ternary cathode material coated with bimetallic oxide.

[0071] Step 5: The modified high-nickel ternary cathode material is subjected to post-annealing treatment in an oxygen atmosphere. The temperature is increased to 600℃ at a rate of 2℃ / min and held for 3 hours. The temperature is then reduced to room temperature at a rate of 2℃ / min to obtain a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer.

[0072] Example 6

[0073] This embodiment provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The only difference from Embodiment 1 is that the number of cycles in the fourth step is replaced by 15 cycles instead of 5. All other steps are completely the same as in Embodiment 1.

[0074] Example 7

[0075] This embodiment provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The only difference from Embodiment 2 is that the LiNi in the first step is... 0.83 Co 0.12 Mn 0.05 The O2 cathode material was replaced with LiNi. 0.6 Co 0.2 Mn 0.2 For the O2 cathode material, the other steps are completely consistent with those in Example 2.

[0076] Example 8

[0077] This embodiment provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The only difference from Embodiment 2 is that the number of cycles in the fourth step is replaced with 25 cycles instead of 15. All other steps are completely the same as in Embodiment 2.

[0078] Example 9

[0079] This embodiment provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The only difference from Embodiment 2 is that the heat preservation time in step 5, which is 3h, is replaced with 2h. The other steps are completely the same as in Embodiment 2.

[0080] Comparative Example 1

[0081] This embodiment provides a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer and its preparation method. The preparation method specifically includes the following steps:

[0082] Step 1, LiNi lithium-ion battery 0.83 Co 0.12 Mn 0.05 O2 cathode material powder is filtered through a sieve, uniformly dispersed in a sample tray, and placed in an atomic layer deposition reaction chamber, where the sieve is 400 mesh.

[0083] Step 2: Nitrogen gas is introduced into the atomic layer deposition system as a carrier gas, and the temperature is raised to 200°C;

[0084] Step 3: Preheat the trimethylaluminum and tris(diethylamine)tert-butylamine niobium precursors required for the deposition process to 30°C and 120°C, respectively;

[0085] Step 4: First, trimethylaluminum precursor is introduced into the reaction chamber, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Water precursor is then introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. Next, tri(diethylamine)tert-butylamine niobium precursor is introduced, with a pulse time of 1.5s, a reaction time of 10s, and a purge time of 60s. Water precursor is then introduced, with a pulse time of 0.2s, a reaction time of 10s, and a purge time of 60s. This sequence of alternating deposition and repeated cycle 15 times yields a high-nickel ternary cathode material coated with bimetallic oxide.

[0086] Performance testing

[0087] like Figure 1 The image shown is a scanning electron microscope image of a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer prepared in Example 1 of the present invention. It can be seen that the sample consists of spherical secondary particles formed by the aggregation of brick-shaped primary particles, and the diameter of the secondary particles is about 10 micrometers.

[0088] like Figure 2 The image shown is an X-ray diffraction pattern of a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer prepared in Example 2 of this invention. It can be seen that this material still maintains... The space group, NaFeO2, has a hexagonal layered structure. The (006) / (012) and (018) / (110) diffraction peaks are clearly split, indicating that its layered structure is well preserved.

[0089] like Figure 3 The figure shows the constant current charge-discharge curve of a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer prepared in Example 2 of the present invention. The first discharge capacity can reach 203 mAh / g at a current density of 0.2C.

[0090] like Figure 4 The figure shows the cycling performance of a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer prepared in Example 2 of the present invention. The results show that at a current density of 0.2C, after 100 cycles, the discharge specific capacity is still 183.3 mAh / g, and the capacity retention rate is as high as 90.7%.

[0091] like Figure 5 As shown, the rate performance diagrams of a high-nickel ternary cathode material prepared in Examples 2, 8 and Comparative Example 1 of the present invention can be seen. It can be found that at current densities of 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0C, the high-nickel ternary cathode material corresponding to Example 2 has a higher specific capacity and exhibits excellent rate performance.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer, characterized in that, On the high-nickel ternary cathode material, there are nano-coatings A of metal oxide A and B of metal oxide B in sequence. Coatings A and B exist alternately. One alternation of coating A and coating B constitutes one repeating cycle. The number of repeating cycles is N, where N is 3-100. The total coating thickness after repeated application of nano-coating A of metal oxide A and nano-coating B of metal oxide B is 0.6-20 nm. The metal oxide A and metal oxide B are different metal oxides; The high-nickel ternary cathode material modified by the bimetallic gradient diffusion layer consists of spherical secondary particles formed by the agglomeration of brick-shaped primary particles, with a diameter of 8-12 micrometers.

2. The high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer according to claim 1, characterized in that, The high-nickel ternary cathode material is LiNi. 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.83 Co 0.12 Mn 0.05 O2 or LiNi 0.90 Co 0.05 Mn 0.05 One or more of O2.

3. The high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer according to claim 2, characterized in that, The metal oxide A and metal oxide B are obtained from metal precursor A and metal precursor B, respectively. Metal precursor A and metal precursor B include one or more of lithium tert-butoxide, trimethylaluminum, diethylzinc, titanium tetraisopropoxide, tetra(dimethylamine)hafnium, tetra(dimethylamine)tin, tri(diethylamine)tert-butylamineniobium, ferrocene, tetra(dimethylamino)vanadium, tetra(dimethylamino)zirconium, and tantalum acetate, and metal precursor A and metal precursor B are different.

4. A method for preparing a high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer according to any one of claims 1-3, comprising the following steps: Step 1: Filter the high-nickel ternary cathode material powder of lithium-ion battery through a sieve, disperse it evenly in the sample tray, and place it in the atomic layer deposition reaction chamber; Step 2: Inert gas is introduced into the atomic layer deposition system as a carrier gas, and the temperature is raised to the target deposition temperature; Step 3: Preheat metal precursor A and metal precursor B, which are required for the deposition process, respectively; Step 4: Metal precursor A, water precursor, metal precursor B, and water precursor are sequentially introduced into the reaction chamber. After each precursor is introduced, it is deposited in the order of pulse-reaction-purge. Metal precursor A-water precursor-metal precursor B-water precursor constitutes one deposition cycle. The number of deposition cycles is N, where N is 3-100. This process is repeated to obtain a high-nickel ternary cathode material coated with bimetallic oxide. Step 5: Perform post-annealing treatment on the above-coated high-nickel ternary cathode material to obtain the high-nickel ternary cathode material modified with bimetallic gradient diffusion layer.

5. The preparation method according to claim 4, characterized in that, In step 1, the high-nickel ternary cathode material for the lithium-ion battery is LiNi. 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.83 Co 0.12 Mn 0.05 O2, LiNi 0.90 Co 0.05 Mn 0.05 One or more of the O2 materials.

6. The preparation method according to claim 4, characterized in that, In step 2, the inert gas is one or more of nitrogen and argon, and the target deposition temperature is set to 150-300℃.

7. The preparation method according to any one of claims 4-6, characterized in that, In step 3, metal precursor A and metal precursor B each include one or more of lithium tert-butoxide, trimethylaluminum, diethylzinc, titanium tetraisopropoxide, tetra(dimethylamine)hafnium, tetra(dimethylamine)tin, tri(diethylamine)tert-butylamineniobium, ferrocene, tetra(dimethylamino)vanadium, tetra(dimethylamino)zirconium, and tantalum acetate, and metal precursor A and metal precursor B are different; the preheating temperatures of metal precursor A and metal precursor B are 30-180℃, respectively.

8. The preparation method according to claim 4, characterized in that, In step 4, the pulse time of metal precursor A is 0.1–5 s, the reaction time is 5–30 s, and the purging time is 30–60 s; the pulse time of metal precursor B is 0.1–5 s, the reaction time is 5–30 s, and the purging time is 30–60 s; the pulse time of water precursor is 0.1–5 s, the reaction time is 5–30 s, and the purging time is 30–60 s; and the number of deposition cycles N is 3–40.

9. The preparation method according to claim 4, characterized in that, In step 5, the atmosphere used for annealing is one or more of nitrogen, argon, and oxygen, the heating rate is 1-5℃ / min, the annealing temperature is 400-700℃, and the cooling rate is 1-5℃ / min.

10. A high-nickel ternary cathode material modified with a bimetallic gradient diffusion layer prepared by the method according to any one of claims 4-9.

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