High-nickel positive electrode material as well as preparation method and application thereof

Abstract

The invention provides a high-nickel positive electrode material and a preparation method and application thereof, and the preparation method comprises the following steps: (1) mixing a high-nickel precursor material with a first lithium salt, and carrying out first sintering treatment in a first oxidizing atmosphere to obtain an intermediate material; and (2) the intermediate material is mixed with a second lithium salt, second sintering treatment is performed in a second oxidizing atmosphere, the high-nickel positive electrode material is obtained, and the first lithium salt comprises at least one selected from lithium carbonate, lithium bicarbonate, lithium nitrate, lithium chloride, lithium fluoride, lithium phosphate, lithium sulfate, lithium acetate and lithium oxalate. According to the method, the first lithium salt with lower cost is used for replacing part of lithium hydroxide and is combined with a step-by-step sintering method, so that the preparation of the high-nickel positive electrode material can be carried out in an air atmosphere, the production cost and the oxygen consumption cost are greatly reduced, the electrochemical performance of the material can be ensured, and the method is more suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the field of lithium ion batteries, and in particular to a high-nickel positive electrode material and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries have the advantages of low cost, high operating voltage, large battery release volume, and recyclability, and can adapt to the development of electrochemical energy storage devices. As an indispensable component of lithium-ion batteries, lithium-ion battery positive electrode materials have also received widespread attention. Ternary positive electrode materials, especially high-nickel ternary positive electrode materials, are currently the focus of research and development due to their advantages such as large capacity and low cost. The preparation of ternary positive electrode materials is generally prepared by mixing M(OH)2 (M is nickel, cobalt, manganese, aluminum) precursors with lithium salts and sintering them at high temperatures. For high-nickel ternary materials, lithium hydroxide is used as a lithium source in a pure oxygen atmosphere, and positive electrode materials with better performance can be obtained by doping or coating, which not only increases the difficulty of manufacturing, but also increases the processing cost. Considering the cost and corrosiveness of raw materials, lithium carbonate and lithium hydroxide are generally used as lithium sources in industry. For high-nickel ternary positive electrode materials, only lithium hydroxide can be used and sintered in a pure oxygen atmosphere. If lithium carbonate is used or sintered in an air atmosphere, the obtained product has a low initial capacity, high residual lithium, and poor cycle performance, which makes it difficult to use as a positive electrode active material for lithium-ion batteries. However, lithium hydroxide has the following disadvantages as a lithium source: (1) lithium hydroxide is extremely corrosive and has a pungent odor, which can burn the eyes, skin and upper respiratory tract, posing a safety hazard; (2) lithium hydroxide that can be used industrially contains crystal water, which is released when mixed with precursors and heated, which is not conducive to the uniform mixing of raw materials; (3) lithium hydroxide has strong water absorption and is easy to react with water and carbon dioxide in the air. It has high requirements for the humidity of the production environment and is not easy to store; (4) lithium hydroxide has more manufacturing processes than lithium carbonate, and the cost is higher. Therefore, it is urgent to provide a preparation method for high-nickel positive electrode materials to reduce production costs and oxygen costs, which is suitable for industrial production. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present invention provides a method for preparing a high-nickel positive electrode material, which can be prepared in an air atmosphere by using a first lithium salt with lower cost, such as lithium carbonate, to replace part of lithium hydroxide in combination with a step-by-step sintering method, thereby greatly reducing the production cost and oxygen cost. At the same time, the method can ensure the electrochemical properties of the material, has good process stability, and is suitable for industrial production.

[0004] To this end, the first aspect of the present invention provides a method for preparing a high-nickel positive electrode material, comprising the following steps:

[0005] (1) mixing a high-nickel precursor material with a first lithium salt, and performing a first sintering treatment in a first oxidizing atmosphere to obtain an intermediate material;

[0006] (2) mixing the intermediate material with a second lithium salt, and performing a second sintering treatment in a second oxidizing atmosphere to obtain the high-nickel positive electrode material;

[0007] Wherein, the first lithium salt includes at least one selected from lithium carbonate, lithium bicarbonate, lithium nitrate, lithium chloride, lithium fluoride, lithium phosphate, lithium sulfate, lithium acetate, and lithium oxalate.

[0008] In order to solve the deficiencies in the prior art, the present invention uses a first lithium salt with a lower cost than lithium hydroxide, such as lithium carbonate, to replace part of the lithium hydroxide and mix it with a high-nickel precursor material. Specifically, the lithium content in lithium carbonate is higher than that in lithium hydroxide, and the unit price of battery-grade lithium carbonate is also lower than that of lithium hydroxide. In addition, lithium hydroxide has disadvantages such as corrosiveness. The use of lithium carbonate to replace part of lithium hydroxide for the preparation of high-nickel positive electrode materials can greatly reduce the cost of raw materials for high-nickel positive electrode materials, simplify the manufacturing process, and reduce safety hazards. In addition, combined with the step-by-step sintering method, the sintering and preparation of raw materials can be achieved in an air atmosphere, which reduces the amount of pure oxygen used, making the preparation method more suitable for industrial production.

[0009] According to an embodiment of the present invention, the first sintering treatment in step (1) includes: sintering at 300-1000° C. for 1-36 hours.

[0010] According to an embodiment of the present invention, the second sintering treatment in step (2) includes: sintering at 600-900°C for 1-24h. In the step-by-step sintering, the lithium source used in the first sintering process is more diverse, and on the premise of ensuring that the lithium source is provided to the high-nickel material, no other inert substances are left to affect the electrochemical properties of the final high-nickel material; the second sintering process uses a small amount of active lithium source such as lithium hydroxide, so that the lithium ratio in the final material is close to the stoichiometric ratio, ensuring the best electrochemical properties of the material.

[0011] According to an embodiment of the present invention, in step (1), the ratio of the molar number of lithium element in the first lithium salt to the total molar number of metal elements in the high-nickel precursor material is (0.05-0.95): 1, preferably (0.3-0.7): 1. When the amount of the first lithium salt added is too low, the advantageous effect of the present invention is not obvious; when the amount added is too high, more inert substances, such as lithium carbonate, will remain on the surface of the material, reducing the specific capacity and cycle stability of the final material, while affecting the processing performance of the material.

[0012] According to an embodiment of the present invention, in step (2), the ratio of the molar number of lithium element in the second lithium salt to the total molar number of metal elements other than lithium element in the intermediate material is (0.05-1):1, preferably (0.25-0.85):1.

[0013] According to an embodiment of the present invention, the sum of the ratio of the molar number of lithium element in the first lithium salt to the total molar number of metal elements in the high-nickel precursor material in step (1) and the ratio of the molar number of lithium element in the second lithium salt to the total molar number of metal elements other than lithium element in the intermediate material in step (2) is (0.95-1.15): 1. Thus, the final total amount of lithium added is close to the stoichiometric ratio of the material. If the total amount of lithium added is too low, the specific capacity of the material will be affected. If it is too high, more lithium carbonate and lithium hydroxide will remain, which will not only reduce the specific capacity but also affect the processing performance of the material.

[0014] According to an embodiment of the present invention, the high-nickel precursor material is selected from at least one of hydroxides, oxides, and carbonates, preferably hydroxides.

[0015] According to an embodiment of the present invention, the first oxidizing atmosphere and the second oxidizing atmosphere are independently selected from air or oxygen.

[0016] According to an embodiment of the present invention, the second lithium salt in step (2) comprises at least one selected from lithium hydroxide, lithium oxide, lithium peroxide, lithium nitrate, and lithium chloride, preferably lithium hydroxide.

[0017] A second aspect of the present invention provides a high-nickel positive electrode material, which is prepared according to the preparation method described in the first aspect.

[0018] The high-nickel positive electrode material prepared by the preparation method provided in the first aspect has a low residual lithium content, excellent rate discharge capacity and stable cycle performance.

[0019] The third aspect of the present invention provides the use of the high-nickel positive electrode material described in the second aspect in a lithium-ion battery.

[0020] The high-nickel positive electrode material provided in the second aspect of the present invention has a low residual lithium content, excellent rate discharge capacity and stable cycle performance, and can be applied to the positive electrode of a lithium-ion battery.

[0021] A fourth aspect of the present invention provides a lithium-ion battery, wherein the lithium-ion battery comprises the high-nickel positive electrode material described in the second aspect.

[0022] Since the high-nickel positive electrode material provided in the second aspect of the present invention has a low residual lithium content, excellent rate discharge capacity and stable cycle performance, using it in a lithium-ion battery can make the lithium-ion battery have excellent electrochemical properties.

[0023] The beneficial effects of the present invention compared to the prior art are as follows:

[0024] The preparation method of the high-nickel positive electrode material provided by the present invention uses a low-cost first lithium source such as lithium carbonate to replace part of the lithium hydroxide as a lithium source, thereby reducing the use of lithium hydroxide, greatly reducing the production cost, and being more friendly to employees and the production environment. At the same time, the step-by-step sintering method is combined to allow the precursor material and the intermediate material to be sintered in an air atmosphere, reducing the amount of pure oxygen used. The preparation method provided by the present invention is highly versatile and can be applied to the preparation of various high-nickel positive electrode materials such as polycrystalline, single crystal and water-washed, and the obtained high-nickel positive electrode material has excellent electrochemical properties, good rate discharge capacity and stable cycle performance.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0027] Figure 1 The SEM image of the high nickel positive electrode material prepared in Example 1 of the present invention is shown;

[0028] Figure 2 The SEM image of the high-nickel positive electrode material prepared in Example 1 of the present invention at high magnification is shown. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0030] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0031] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0032] In order to make the present invention more easily understood, certain technical and scientific terms are specifically defined below. Unless otherwise clearly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by those skilled in the art to which the present invention belongs.

[0033] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention but not excluding other contents.

[0034] As used herein, the terms "optionally", "optional" or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0035] In this article, the term "high-nickel positive electrode material" refers to a positive electrode material with a molar content of nickel element ≧50%.

[0036] According to an embodiment of the present invention, the present invention provides a method for preparing a high-nickel positive electrode material, comprising the following steps:

[0037] (1) A high-nickel precursor material is mixed with a first lithium salt and subjected to a first sintering treatment in a first oxidizing atmosphere to obtain an intermediate material.

[0038] Among them, in addition to nickel, other metal elements in the high-nickel precursor material can be one or more of Co, Mn, B, Al, Ga, Si, Mg, Ti, V, Cr, La, Zr, W, Mo, and W. The high-nickel precursor material can be a hydroxide, an oxide, or a carbonate, preferably a hydroxide, such as Ni 0.88 Co 0.09 Al 0.03 (OH)2、Ni 0.83 Co 0.12 Mn 0.05 (OH)2, etc. The first lithium salt includes but is not limited to lithium carbonate, lithium bicarbonate, lithium nitrate, lithium chloride, lithium fluoride, lithium phosphate, lithium sulfate, lithium acetate, and lithium oxalate.

[0039] According to a specific embodiment of the present invention, the preparation method of the high nickel precursor material can adopt any conventional preparation method, such as a physical method or a chemical method, including but not limited to a solid phase method, a coprecipitation method, a sol-gel method, a spray drying method, and a combustion method, etc. At the same time, the morphology of the high nickel precursor material can also be a conventional morphology, such as a sphere, a rod, a needle, a sheet or an irregular shape.

[0040] According to a specific embodiment of the present invention, the ratio of the molar number of lithium element in the first lithium salt to the total molar number of metal elements in the high-nickel precursor material is (0.05-0.95):1, preferably (0.3-0.7):1, including but not limited to any point value of 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1 or a range value between any two of them.

[0041] According to a specific embodiment of the present invention, the first oxidizing atmosphere may be air or oxygen, or an oxidizing gas obtained by adjusting the ratio of oxygen to other gases, and the other gases may be nitrogen or argon.

[0042] According to a specific embodiment of the present invention, the first sintering treatment includes: sintering at 300-1000°C (including but not limited to any one of 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C or any range between two thereof) for 1-36h (including but not limited to any one of 1h, 3h, 6h, 9h, 12h, 15h, 18h, 21h, 24h, 27h, 30h, 33h, 36h or any range between two thereof);

[0043] (2) Mixing the intermediate material with a second lithium salt and performing a second sintering treatment in a second oxidizing atmosphere to obtain the high-nickel positive electrode material.

[0044] Wherein, the second lithium salt includes but is not limited to lithium hydroxide, lithium oxide, lithium peroxide, lithium nitrate, lithium chloride, preferably lithium hydroxide. The ratio of the molar number of lithium element in the second lithium salt to the total molar number of metal elements other than lithium element in the intermediate material is (0.05-1):1, preferably (0.25-0.85):1, including but not limited to any one of 0.32:1, 0.42:1, 0.52:1, 0.62:1, 0.72:1, 0.82:1 or any range between two thereof.

[0045] According to a specific embodiment of the present invention, the sum of the ratio of the molar number of lithium element in the first lithium salt in step (1) to the total molar number of metal elements in the high-nickel precursor material and the ratio of the molar number of lithium element in the second lithium salt in step (2) to the total molar number of metal elements other than lithium element in the intermediate material is (0.95-1.15):1, including but not limited to any one of 0.95:1, 1.05:1, 1.15:1 or a range between any two of them. For example, in step (1), the ratio of the molar number of lithium element in the first lithium salt to the total molar number of metal elements in the high-nickel precursor material is 0.50:1, and the ratio of the molar number of lithium element in the second lithium salt to the total molar number of metal elements other than lithium element in the intermediate material in step (2) is 0.52:1. Then, the sum of the ratio of the molar number of lithium element in the first lithium salt to the total molar number of metal elements in the high-nickel precursor material and the ratio of the molar number of lithium element in the second lithium salt to the total molar number of metal elements other than lithium element in the intermediate material in step (2) is 1.02:1.

[0046] According to a specific embodiment of the present invention, the second sintering treatment includes: sintering at 600-900°C (including but not limited to any one of 600°C, 650°C, 700°C, 720°C, 750°C, 800°C, 850°C, 900°C or a range between any two of them) for 1-24h (including but not limited to any one of 1h, 3h, 6h, 9h, 12h, 15h, 18h, 21h, 24h or a range between any two of them).

[0047] According to a specific embodiment of the present invention, the second oxidizing atmosphere may be air or oxygen, or an oxidizing gas obtained by adjusting the ratio of oxygen to other gases, and the other gases may be nitrogen or argon.

[0048] According to a specific embodiment of the present invention, the preparation method may further include crushing and screening the high-nickel positive electrode material after step (2) to obtain a polycrystalline or single-crystalline high-nickel positive electrode material, and subsequently washing the material with water to further reduce the amount of residual alkali in the material.

[0049] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0050] Example 1

[0051] (1) Lithium carbonate and D 50 12μm Ni 0.88 Co 0.09 Al 0.03 The (OH)2 precursor was mixed in a molar ratio of Li:Me(Ni, Co, Al)=0.50:1, and sintered at 750°C for 6h with a heating rate of 2°C / min to obtain a sintered material;

[0052] (2) The above sintering material was mixed with lithium hydroxide in a molar ratio of Li:Me(Ni, Co, Al)=0.52:1, and sintered at 720°C for 12h with a heating rate of 2°C / min to obtain a high-nickel positive electrode material.

[0053] Example 2

[0054] (1) Lithium carbonate and D 50 12μm Ni 0.88 Co 0.09 Al 0.03 The (OH)2 precursor was mixed in a molar ratio of Li:Me(Ni, Co, Al)=0.60:1, and sintered at 800°C for 6h with a heating rate of 2°C / min to obtain a sintered material;

[0055] (2) The above sintering material was mixed with lithium hydroxide in a molar ratio of Li:Me(Ni, Co, Al)=0.42:1, and sintered at 720°C for 12h with a heating rate of 2°C / min to obtain a high-nickel positive electrode material.

[0056] Example 3

[0057] (1) Lithium carbonate and D 50 12μm Ni 0.83 Co 0.12 Mn 0.05 The (OH)2 precursor was mixed in a molar ratio of Li:Me(Ni, Co, Mn)=0.60:1, and sintered at 800°C for 6h with a heating rate of 2°C / min to obtain a sintered material;

[0058] (2) The above sintering material was mixed with lithium hydroxide in a molar ratio of Li:Me(Ni, Co, Mn)=0.42:1, and sintered at 720°C for 12h with a heating rate of 2°C / min to obtain a high-nickel positive electrode material.

[0059] Example 4

[0060] (1) Lithium carbonate and D 50 3μm Ni 0.83 Co 0.12 Mn 0.05The (OH)2 precursor was mixed in a molar ratio of Li:Me(Ni, Co, Mn)=0.70:1, and sintered at 850°C for 6h with a heating rate of 2°C / min to obtain a sintered material;

[0061] (2) The above sintering material was mixed with lithium hydroxide in a molar ratio of Li:Me(Ni, Co, Mn)=0.32:1, and sintered at 800°C for 12h with a heating rate of 2°C / min to obtain a high-nickel positive electrode material.

[0062] Example 5

[0063] (1) Lithium carbonate and D 50 12μm Ni 0.83 Co 0.12 Mn 0.05 The (OH)2 precursor was mixed in a molar ratio of Li:Me(Ni, Co, Mn)=0.30:1, and sintered at 500°C for 6h with a heating rate of 2°C / min to obtain a sintered material;

[0064] (2) The above sintering material was mixed with lithium hydroxide in a molar ratio of Li:Me(Ni, Co, Mn)=0.72:1, and sintered at 720°C for 12h with a heating rate of 2°C / min to obtain a high-nickel positive electrode material.

[0065] Comparative Example 1

[0066] Lithium carbonate and D 50 12μm Ni 0.88 Co 0.09 Al 0.03 The (OH)2 precursor was mixed in a molar ratio of Li:Me(Ni, Co, Al)=1.02:1, sintered at 730°C for 12h with a heating rate of 2°C / min to obtain a high-nickel positive electrode material.

[0067] Comparative Example 2

[0068] Lithium hydroxide and D 50 12μm Ni 0.88 Co 0.09 Al 0.03 The (OH)2 precursor was mixed in a molar ratio of Li:Me(Ni, Co, Al)=1.02:1, sintered at 730°C for 12h with a heating rate of 2°C / min to obtain a high-nickel positive electrode material.

[0069] Comparative Example 3

[0070] Lithium hydroxide and lithium carbonate are mixed in a lithium ratio of 1:1, and then the mixture is mixed with D 50 12μm Ni 0.88 Co 0.09 Al0.03 The (OH)2 precursor was mixed in a molar ratio of Li:Me(Ni, Co, Al)=1.02:1, sintered at 730°C for 12h with a heating rate of 2°C / min to obtain a high-nickel positive electrode material.

[0071] Comparative Example 4

[0072] (1) Lithium hydroxide and D 50 12μm Ni 0.88 Co 0.09 Al 0.03 The (OH)2 precursor was mixed in a molar ratio of Li:Me(Ni, Co, Al)=0.50:1, and sintered at 750°C for 6h with a heating rate of 2°C / min to obtain a sintered material;

[0073] (2) The above sintering material was mixed with lithium hydroxide in a molar ratio of Li:Me(Ni, Co, Al)=0.52:1, and sintered at 720°C for 12h with a heating rate of 2°C / min to obtain a high-nickel positive electrode material.

[0074] Comparative Example 5

[0075] (1) Lithium carbonate and D 50 12μm Ni 0.88 Co 0.09 Al 0.03 The (OH)2 precursor was mixed in a molar ratio of Li:Me(Ni, Co, Al)=0.50:1, and sintered at 750°C for 6h with a heating rate of 2°C / min to obtain a sintered material;

[0076] (2) The above sintering material was mixed with lithium carbonate in a molar ratio of Li:Me(Ni, Co, Al)=0.52:1, and sintered at 720°C for 12h with a heating rate of 2°C / min to obtain a high-nickel positive electrode material.

[0077] Performance Testing

[0078] 1. Morphology analysis

[0079] The high nickel cathode material prepared in Example 1 was subjected to SEM testing. Figure 1-2 The results show that the high nickel positive electrode material prepared in Example 1 has a relatively uniform particle size and a relatively smooth surface.

[0080] 2. Electrochemical performance test

[0081] The high nickel positive electrode materials prepared in Examples 1-5 and Comparative Examples 1-5 were used to make half-cells for testing, and the specific steps were as follows:

[0082] Polyvinylidene fluoride (PVDF, binder) was added to N-methylpyrrolidone (NMP, solvent), and after magnetic stirring and dissolution, superconducting carbon black (Super P, SP) and conductive graphite (KS6) were added and stirred for 0.5h, and then high nickel material was added and stirred for 1h before coating, wherein high nickel material: (SP+KS6): PVDF = 90:5 (SP:KS6 = 1:1): 5 (wt%), solid content 40%. The coated pole piece was dried at 100°C, rolled, punched, and dried to constant weight, and finally transferred to an argon glove box, and a 2025 button cell was assembled with a lithium sheet as the counter electrode. The electrochemical performance of each group of batteries was tested, and the results are shown in Table 1.

[0083] Table 1 Electrochemical performance test results of each group of batteries

[0084]

[0085] It can be seen from Table 1 that the rate performance, cycle performance and residual alkali content of the batteries prepared based on Examples 1-5 are comparable to those of the batteries prepared based on Comparative Examples 2 and 4 using lithium hydroxide as the lithium source, and are superior to the batteries prepared based on Comparative Examples 1, 3 and 5, indicating that the use of lithium carbonate instead of part of the lithium hydroxide combined with the step-by-step sintering method can reduce the production cost while ensuring the electrochemical properties of the synthetic material.

[0086] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0087] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a high-nickel positive electrode material, characterized in that: The following steps are involved: (1) mixing a high-nickel precursor material with a first lithium salt, and performing a first sintering treatment in a first oxidizing atmosphere to obtain an intermediate material; (2) mixing the intermediate material with a second lithium salt, and performing a second sintering treatment in a second oxidizing atmosphere to obtain the high-nickel positive electrode material; Wherein, the first lithium salt includes at least one selected from lithium carbonate, lithium bicarbonate, lithium nitrate, lithium chloride, lithium fluoride, lithium phosphate, lithium sulfate, lithium acetate, and lithium oxalate.

2. The preparation method according to claim 1, characterized in that: The first sintering treatment in step (1) includes: sintering at 300-1000° C. for 1-36 hours; Optionally, the second sintering treatment in step (2) includes: sintering at 600-900° C. for 1-24 hours.

3. The preparation method according to claim 1, characterized in that: In step (1), the ratio of the molar number of lithium element in the first lithium salt to the total molar number of metal elements in the high-nickel precursor material is (0.05-0.95):1, preferably (0.3-0.7):1; Optionally, in step (2), the ratio of the molar number of lithium element in the second lithium salt to the total molar number of metal elements other than lithium element in the intermediate material is (0.05-1):1, preferably (0.25-0.85):

1.

4. The preparation method according to claim 1, characterized in that: The sum of the ratio of the molar number of lithium element in the first lithium salt to the total molar number of metal elements in the high-nickel precursor material in step (1) and the ratio of the molar number of lithium element in the second lithium salt to the total molar number of metal elements other than lithium element in the intermediate material in step (2) is (0.95-1.15):

1.

5. The preparation method according to claim 1, characterized in that: The high-nickel precursor material is selected from at least one of hydroxides, oxides, and carbonates, preferably hydroxides.

6. The preparation method according to claim 1, characterized in that: The first oxidizing atmosphere and the second oxidizing atmosphere are each independently selected from air or oxygen.

7. The preparation method according to claim 1, characterized in that: In step (2), the second lithium salt comprises at least one selected from lithium hydroxide, lithium oxide, lithium peroxide, lithium nitrate and lithium chloride, preferably lithium hydroxide.

8. A high nickel positive electrode material, characterized in that: The high-nickel positive electrode material is prepared according to the preparation method according to any one of claims 1-7.

9. Use of the high-nickel positive electrode material according to claim 8 in lithium-ion batteries.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the high-nickel positive electrode material according to claim 8.

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