A lithium nickel manganese oxide cathode material, its preparation method and application

Abstract

This invention discloses a lithium nickel manganese oxide (LNMO) cathode material, its preparation method, and its applications, relating to the field of lithium battery technology. Organic materials such as titanate, aluminate, and borate esters are sprayed into a fluidized bed and mixed with the flowing cathode material, achieving uniform coating of the cathode material by the coating material. After coating, the material can be rapidly dried in the fluidized bed, eliminating the need for a separate drying step and effectively reducing the agglomeration and segregation of the coating agent on the cathode surface. Fluidized bed coating allows the coating agent to be tightly and firmly coated on the surface of the LNMO cathode material, avoiding the prolonged immersion of the cathode in water or other solvents as in conventional liquid-phase coating methods. Simultaneously, the fluidized bed itself has a pulverizing and dispersing effect, reducing the requirements for LNMO dispersibility. The coating layer formed by this method is stable and not easily detached, effectively preventing direct contact between the LNMO cathode material surface and the electrolyte, effectively reducing manganese dissolution and improving the material's cycle stability.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and more specifically, to a lithium nickel manganese oxide cathode material, its preparation method, and its application. Background Technology

[0002] Currently, lithium-ion batteries are widely used. However, with the increasing demand for energy storage, lithium-ion batteries will eventually reach their density limit (approximately 400 Wh / kg under ideal conditions). -1 Therefore, there is a desire to develop batteries with high energy storage capacity and suitability for large-scale fabrication. Cathode materials are a decisive factor affecting electrochemical performance, playing a dominant role in battery capacity, energy density, and cycle performance. Therefore, developing high-energy-density cathode materials is a crucial means to overcome the current energy limitations of lithium-ion batteries.

[0003] Based on the working principle of lithium-ion batteries, the specifications, capacity, and operating voltage of the cathode material directly affect the energy density of the battery. Therefore, utilizing cathode materials with high capacity or high operating voltage is an effective way to improve the energy density of lithium-ion batteries and overcome this limitation. Spinel LiNi 0.5 Mn 1.5 O4 (LNMO) is low in cost and easy to manufacture industrially, and has an ultra-high discharge platform of approximately 4.7V (vs. Li / Li). + LNMO also boasts a high energy density of approximately 650 Wh / kgd, which is 1.63 times that of LiMn₂O₄ and 1.31 times that of LiFePO₄. Therefore, high-pressure LNMO with a spinel structure is considered one of the most promising cathode materials for next-generation lithium-ion batteries due to its high energy density, abundant raw materials, and large-scale production potential.

[0004] However, the cycling performance of batch LNMO is poor, and therefore it cannot fully meet the requirements of high power. The most critical problem of LNMO is the short cycle life caused by rapid capacity decline. This is mainly because when high-pressure spinel LNMO is cycled under high pressure, its surface comes into contact with the electrolyte and metal ions are dissolved, which seriously affects the cycling and rate performance of the material; and the highly active surface is prone to react with the electrolyte, which reduces the cycling performance and safety.

[0005] Existing technologies often employ mechanical mixing of metal oxides and cathode materials, followed by high-temperature sintering to achieve a coating effect. Metal oxides offer structural stability and effectively protect the material. However, for small-molecule metal oxide coatings, reducing the impact of the electrolyte requires surface stacking to achieve a certain thickness. This makes it difficult to obtain a uniform coating layer through mechanical mixing, and the coating layer is prone to deformation during cycling due to the deformation of the cathode material and the presence of Li. + De-intercalation can lead to detachment, reducing cycle performance and safety.

[0006] In addition to the solid-phase coating methods mentioned above, solution co-precipitation and sol-gel methods can also be used to coat the surface of cathode materials. While conventional liquid-phase coating methods can uniformly coat the cathode material with a layer of metal oxide or organic matter, improving its cycle performance, the process is complex and costly. Atomic layer deposition (ALD) coating can achieve uniform coating layers of 1nm-2nm thickness with excellent performance, but it requires sophisticated equipment and raw materials, resulting in higher costs and hindering industrial production.

[0007] Therefore, there is an urgent need to develop a simple and low-cost coating method that can significantly improve the recycling performance of materials while achieving uniform coating.

[0008] In view of this, the present invention is proposed. Summary of the Invention

[0009] The purpose of this invention is to provide a lithium nickel manganese oxide cathode material, its preparation method and application, aiming to provide a simple and low-cost coating method that can significantly improve the cycle performance of the material while achieving uniform coating effect.

[0010] This invention is implemented as follows:

[0011] In a first aspect, the present invention provides a method for preparing a lithium nickel manganese oxide cathode material, comprising:

[0012] Provide lithium nickel manganese oxide cathode materials to be modified;

[0013] The coating material is obtained by mixing the coating raw material and solvent. The coating material is sprayed onto the surface of the lithium nickel manganese oxide cathode material to be modified in a fluidized bed and then dried in the fluidized bed.

[0014] The coating material is selected from at least one of titanate, aluminate and borate.

[0015] In an optional embodiment, the coating material is selected from at least two of titanate, aluminate and borate;

[0016] Preferably, the coating material includes titanate and aluminate, and the mass ratio of titanate to aluminate is 1:(0.5-1.5).

[0017] In an optional embodiment, the mass ratio of the total amount of coating raw material to solvent is 1:(8-10), and the mass ratio of the lithium nickel manganese oxide cathode material to be modified to the coating material is 1:(0.1-0.3).

[0018] Preferably, the solvent is water.

[0019] In an optional embodiment, the inlet temperature of the fluidized bed is controlled to be 100℃-140℃, the outlet temperature of the fluidized bed is controlled to be 40℃-60℃, and the total residence time in the fluidized bed is 10min-200min.

[0020] The coating material is sprayed on the lithium nickel manganese oxide cathode material to be modified after it reaches 40℃-80℃ in the fluidized bed.

[0021] In an optional embodiment, the chemical formula of the lithium nickel manganese oxide cathode material to be modified is Li x Ni y Mn z O2, Li x Ni y Mn z O2, 0.5<x≤0.55, 0.2<y≤0.3, 0.7<z≤0.8, y+z=1.

[0022] In an optional embodiment, the preparation process of the modified lithium nickel manganese oxide cathode material includes: mixing and sintering a nickel cobalt hydroxide precursor, a lithium source and a dopant, controlling the sintering temperature at 900℃-1100℃ and the holding time at 8h-12h.

[0023] Preferably, after the heat preservation is completed, the material is crushed and passed through a 300-500 mesh sieve.

[0024] In an optional embodiment, the dopant element contained in the dopant is selected from at least one of Sr, Sb and Nb;

[0025] Preferably, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide and lithium oxide; the molar ratio of the total amount of nickel and cobalt in the nickel-cobalt hydroxide precursor to the lithium content in the lithium source is controlled to be 1:(0.50-0.55).

[0026] Secondly, the present invention provides a lithium nickel manganese oxide cathode material, which is prepared by any of the preparation methods described in the foregoing embodiments.

[0027] Thirdly, the present invention provides a positive electrode sheet comprising the lithium nickel manganese oxide positive electrode material of the aforementioned embodiments.

[0028] Fourthly, the present invention provides a lithium battery including the positive electrode sheet of the aforementioned embodiments.

[0029] This invention offers the following advantages: Organic materials such as titanate, aluminate, and borate esters are atomized and sprayed into a fluidized bed using an airflow atomization method, mixing with the flowing cathode material to achieve uniform coating of the cathode material. After coating, the material can be rapidly dried in the fluidized bed, eliminating the need for a separate drying step and effectively reducing the agglomeration and segregation of the coating agent on the cathode surface. The fluidized bed coating method allows the coating agent to be tightly and firmly coated on the surface of lithium nickel manganese oxide (LNMO) cathode material, avoiding the prolonged immersion of the cathode in water or other solvents as in conventional liquid-phase coating methods. Simultaneously, the fluidized bed inherently provides a pulverizing and dispersing effect, reducing the requirements for LNMO dispersibility (even slight agglomeration of the matrix does not affect the coating effect). The coating layer formed by this method is stable and not easily detached, effectively preventing direct contact between the LNMO cathode material surface and the electrolyte, effectively reducing manganese dissolution and improving the material's cycle stability. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The image shows a scanning electron microscope (SEM) image of the cathode material obtained in Example 1.

[0032] Figure 2 A scanning electron microscope image of the cathode material was obtained for Comparative Example 2;

[0033] Figure 3 The image shown is a scanning electron microscope (SEM) image of the cathode material obtained for Comparative Example 3. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0035] To address the issue of coating layer detachment in existing LNMO cathode materials, which negatively impacts cycle performance and safety, the inventors considered using organic materials with excellent film-forming properties to assist in coating. This not only ensures more uniform coating but also allows the long-chain structure of organic molecules to better adhere to the cathode material, resulting in a more stable coating layer during cycling. Furthermore, to address the complexity and high processing costs of traditional liquid-phase coating methods, the inventors optimized the coating process, significantly reducing costs while maintaining effective coating.

[0036] This invention provides a method for preparing lithium nickel manganese oxide cathode material, the steps of which are as follows:

[0037] S1. Provide lithium nickel manganese oxide cathode material to be modified.

[0038] The chemical formula of the lithium nickel manganese oxide cathode material to be modified is Li x Ni y Mn z For O2, 0.5 < x ≤ 0.55, 0.2 < y ≤ 0.3, 0.7 < z ≤ 0.8, and y + z = 1. The lithium nickel manganese oxide cathode material to be modified can be commercially available raw materials or synthesized in-house. Specifically, the values ​​of x can be 0.51, 0.52, 0.53, 0.54, 0.55, etc.; the values ​​of y can be 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.28, 0.30, etc.; and the values ​​of z can be 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, etc.

[0039] In some embodiments, the preparation process of the lithium nickel manganese oxide cathode material to be modified includes: mixing and sintering a nickel cobalt hydroxide precursor, a lithium source and a dopant, controlling the sintering temperature to be 900℃-1100℃, and holding time to be 8h-12h. The product after one sintering is the LNMO cathode material, which can be used for subsequent coating processes.

[0040] Specifically, the sintering temperature can be 900℃, 950℃, 1000℃, 1050℃, 1100℃, etc., and the holding time can be 8h, 9h, 10h, 11h, 12h, etc. The heating rate is unlimited, such as 1℃ / min-5℃ / min, specifically 3℃ / min.

[0041] In some embodiments, after the insulation is completed, the material is crushed and passed through a 300-500 mesh sieve to obtain cathode material with the required particle size for subsequent surface modification. The crushing method is not limited; a common jaw crusher can be used.

[0042] The molar ratio of nickel to manganese in the nickel-cobalt hydroxide precursor corresponds to the molar ratio of nickel to manganese in the chemical formula of the lithium nickel manganese oxide cathode material to be modified. The nickel-cobalt hydroxide precursor can be commercially available or prepared by conventional co-precipitation method.

[0043] In some embodiments, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide, and lithium oxide, and the lithium source can be any one or more of the above; the molar ratio of the total amount of nickel and cobalt in the nickel-cobalt hydroxide precursor to the lithium content in the lithium source is controlled to be 1:(0.50-0.55), such as 1:0.50, 1:0.51, 1:0.52, 1:0.55, 1:0.55, etc.

[0044] In some embodiments, the dopant contains at least one of Sr, Sb, and Nb, and the dopant can be any one or more of these, such as SrCO3, Sb2O3, or Nb2O5. The amount of dopant used can be adjusted according to the content of the dopant element in the target lithium nickel manganese oxide cathode material to be modified.

[0045] S2, fluidized bed coating

[0046] The coating material is obtained by mixing the coating raw material and the solvent. The coating material is sprayed onto the surface of the lithium nickel manganese oxide cathode material to be modified in a fluidized bed and dried in the fluidized bed. The coating raw material is selected from at least one of titanate, aluminate and borate, and the coating raw material can be any one or more of the above.

[0047] It should be noted that organic materials such as titanate, aluminate, and borate are sprayed into the fluidized bed by atomizing the airflow, and mixed with the positive electrode material in a fluid state, so as to achieve uniform coating of the positive electrode material by the coating raw material; after coating, it can be dried quickly in the fluidized bed, eliminating the need for a separate drying step, and effectively reducing the agglomeration and segregation of the coating agent on the positive electrode surface.

[0048] In a preferred embodiment, the coating material is selected from at least two of titanate, aluminate and borate. When the coating material is any two of the above, the coating effect can be improved to a certain extent compared with a single coating material, which is beneficial to the cycle stability of the cathode material.

[0049] In a more preferred embodiment, the coating material includes titanate and aluminate, and the mass ratio of titanate to aluminate is 1:(0.5-1.5). Using titanate and aluminate as a mixed coating material can further improve the electrochemical performance of the cathode material compared to other combinations. Specifically, the mass ratio of titanate to aluminate can be 1:0.5, 1:0.8, 1:1.0, 1:1.2, 1:1.5, etc.

[0050] Furthermore, the mass ratio of the total amount of coating raw material to solvent is 1:(8-10), such as 1:8, 1:8.5, 1:9, 1:9.5, 1:10, etc.; the mass ratio of the lithium nickel manganese oxide cathode material to be modified to the coating material is 1:(0.1-0.3), such as 1:0.1, 1:0.2, 1:0.3, etc. The type of solvent is not limited, such as water. By further adjusting the mass ratio of the total amount of coating raw material to solvent, and the mass ratio of the lithium nickel manganese oxide cathode material to be modified to the coating material, the coating raw material can be coated more uniformly, forming a uniform and stable coating layer.

[0051] In actual operation, the lithium nickel manganese oxide cathode material to be modified is placed in a fluidized bed. The inlet temperature of the fluidized bed is controlled at 100℃-140℃, and the outlet temperature is controlled at 40℃-60℃. After the lithium nickel manganese oxide cathode material enters the fluidized bed and reaches 40℃-80℃, the coating material is sprayed on. The total residence time in the fluidized bed is 10min-200min (e.g., 10min, 30min, 50min, 80min, 100min, 130min, 150min, 180min, 200min, etc.). By precisely controlling the operating parameters of the fluidized bed, the coating material is better coated on the surface of the lithium nickel manganese oxide cathode material to be modified. After rapid drying, a lithium nickel manganese oxide cathode material with a stable coating layer is obtained.

[0052] Specifically, the inlet temperature of the fluidized bed can be 100℃, 110℃, 120℃, 130℃, 140℃, etc., and the outlet temperature of the fluidized bed can be 40℃, 45℃, 50℃, 55℃, 60℃, etc. The material temperature during spraying of the coating material can be 40℃, 50℃, 60℃, 70℃, 80℃, etc.

[0053] This invention provides a lithium nickel manganese oxide (LNMO) cathode material, which is prepared by the preparation method provided in this invention. The coating agent is tightly and firmly coated on the surface of the LNMO cathode material. The resulting coating layer is stable and not easy to fall off, and effectively prevents direct contact between the LNMO cathode material surface and the electrolyte, effectively reducing manganese dissolution and improving the cycle stability of the material.

[0054] This invention also provides a positive electrode sheet, comprising the aforementioned lithium nickel manganese oxide positive electrode material, and may further include a positive electrode current collector. A positive electrode active coating is formed on the positive electrode current collector. The lithium nickel manganese oxide positive electrode material prepared in this invention is dispersed in the positive electrode active coating. Because the lithium nickel manganese oxide positive electrode material provided in this invention has excellent cycle stability, the performance of the positive electrode sheet is correspondingly improved.

[0055] This invention also provides a lithium battery, including the above-mentioned positive electrode, and may further include a negative electrode, electrolyte, separator, etc., to form a complete lithium battery.

[0056] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0057] Example 1

[0058] This embodiment provides a method for preparing lithium nickel manganese oxide cathode material, the steps of which are as follows:

[0059] (1) Preparation of lithium nickel manganese oxide cathode material to be modified

[0060] Provide Ni 0.25 Mn 0.75 The (OH)2 precursor was purchased from Yibin Guangyuan Lithium Battery Co., Ltd., model number Y1NM20106.

[0061] Ni 0.25 Mn 0.75 1 kg of (OH)₂ precursor, 207 g of lithium carbonate, and 5 g of dopants SrCO₃, Sb₂O₃, and Nb₂O₅ were mixed evenly and then heated to 980 °C at a heating rate of 3 °C / min and held for 10 h. After calcination, high-pressure spinel LNMO cathode material Li was obtained. 0.5 Ni 0.25 Mn 0.75 O2, after being crushed by jaw crusher, is passed through a 400-mesh sieve for later use.

[0062] (2) Fluidized bed coating

[0063] 10g of titanate and 10g of aluminate were dissolved in 180g of water to prepare a coating material. This coating material was then wet-coated onto the surface of a 1kg feedstock using a rotating fluidized bed (purchased from [Company Name]). The feedstock was then dried in the fluidized bed until the moisture content was less than 300ppm, yielding a lithium nickel manganese oxide cathode material co-coated with titanate and aluminate. The inlet temperature of the fluidized bed was controlled at 120°C, and the outlet temperature at 50°C. The coating material was sprayed onto the lithium nickel manganese oxide cathode material after it entered the fluidized bed and reached 60°C. The total residence time in the fluidized bed was 40 minutes.

[0064] Example 2

[0065] The only difference between this embodiment and embodiment 1 is that the coating material in step (2) is 30g titanate and 30g aluminate, while the amount of water remains unchanged.

[0066] Example 3

[0067] The only difference between this embodiment and embodiment 1 is that the coating material in step (2) is 10g borate ester and 10g aluminate ester, while the amount of water remains unchanged.

[0068] Example 4

[0069] The only difference between this embodiment and embodiment 1 is that in step (2), 10g of titanate and 10g of aluminate are replaced with 20g of titanate.

[0070] Example 5

[0071] The only difference between this embodiment and embodiment 1 is that in step (2), 10g of titanate and 10g of aluminate are replaced with 20g of aluminate.

[0072] Example 6

[0073] The only difference between this embodiment and embodiment 1 is that the amount of water used in step (2) is 120g.

[0074] Example 7

[0075] The only difference between this embodiment and embodiment 1 is that the amount of water used in step (2) is 240g.

[0076] Example 8

[0077] The only difference between this embodiment and embodiment 1 is that the amount of burning material used in step (2) is 4 kg.

[0078] Example 9

[0079] The only difference between this embodiment and embodiment 1 is that the amount of burning material used in step (2) is 0.4 kg.

[0080] Comparative Example 1

[0081] The only difference between this embodiment and Embodiment 1 is that the coating materials are 100g borate ester and 100g aluminate ester, while the amount of water remains unchanged.

[0082] Comparative Example 2

[0083] The only difference between this embodiment and Embodiment 1 is that step (2) uses a solution co-precipitation method for coating, and the concentration of the coating agent solution is lower. The specific steps are as follows:

[0084] 10g of titanate and 10g of aluminate were dissolved in 980g of water to prepare coating solution A. High-pressure spinel LNMO cathode material was added to solution A and stirred for 1 hour. After filtration and drying, the finished product was obtained.

[0085] Comparative Example 3

[0086] The only difference between this embodiment and embodiment 1 is that the preparation process of the coating material in step (2) is as follows: 10g of alumina, 10g of titanium dioxide and 180g of water are mixed to obtain an inorganic oxide suspension.

[0087] Comparative Example 4

[0088] The only difference between this embodiment and Embodiment 1 is that step (2) uses a solution co-precipitation method for coating. The specific steps are as follows:

[0089] 10g of titanate and 10g of aluminate were dissolved in 180g of water to prepare coating solution A. High-pressure spinel LNMO cathode material was added to solution A and stirred for 1 hour. After filtration and drying, the finished product was obtained.

[0090] Test case

[0091] (1) Taking Example 1 and Comparative Examples 2 and 3 as examples, the obtained ternary cathode materials were observed by scanning electron microscopy (SEM). The SEM images are shown below. Figure 1 , Figure 2 and Figure 3 As shown.

[0092] Depend on Figures 1 to 3 It can be seen that using a fluidized bed to assist in coating organometallic compounds such as titanate and aluminum titanate allows the composite to be tightly and firmly coated on the surface of the LNMO cathode material, which can slow down the agglomeration of the coating layer during traditional wet coating methods and inorganic coating, and make the coating layer more uniform and stable.

[0093] (2) The ternary cathode materials obtained in the examples and comparative examples were used to make 2025 type coin cells and their electrochemical performance was tested. The preparation and testing methods are as follows:

[0094] Ternary cathode: carbon black: PVDF = 90:5:5; anode: lithium metal; electrolyte: Xinzhoubang (M10). The charge / discharge voltage range was 3.5-4.95V. The tests were conducted at different rates (0.1C, 0.2C, 0.5C, 1C) once each, followed by performance testing at room temperature for the 1C capacity and cycle performance. The results are shown in Table 1.

[0095] Table 1. Capacity and Cyclic Performance Test Results

[0096]

[0097]

[0098] As can be seen from Table 1, the ternary cathode material obtained in the examples is more conducive to improving the coin capacity and cycle retention rate of the battery than the ternary cathode material obtained in the comparative examples, and the overall effect of Example 1 is the best.

[0099] The above are merely preferred embodiments of the present invention and are not intended to limit the present 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 method for preparing a lithium nickel manganese oxide cathode material, characterized in that, The application relates to a lithium nickel-manganese oxide positive electrode material and a preparation method thereof. The application provides a lithium nickel-manganese oxide positive electrode material to be modified, a coating raw material and a solvent are mixed to obtain a coating material, the coating material is sprayed to the surface of the lithium nickel-manganese oxide positive electrode material to be modified in a fluidized bed, and drying is performed in the fluidized bed. The coating raw material comprises titanate and aluminate, and the mass ratio of the titanate to the aluminate is 1: (0.5-1.5). The mass ratio of the total amount of the coating raw material to the solvent is 1: (8-10), and the mass ratio of the lithium nickel-manganese oxide positive electrode material to be modified to the coating material is 1: (0.1-0.3).

2. The production method according to claim 1, characterized by, The solvent is water.

3. The preparation method according to claim 2, characterized in that, The inlet temperature of the fluidized bed is controlled to be 100-140 DEG C, the outlet temperature of the fluidized bed is controlled to be 40-60 DEG C, and the total residence time in the fluidized bed is controlled to be 10-200 min.

4. The method of claim 1, wherein, The coating material is sprayed after the material of the lithium nickel-manganese oxide positive electrode material to be modified reaches 40-80 DEG C. The preparation process of the lithium nickel-manganese oxide positive electrode material to be modified comprises the following steps: a nickel-cobalt hydroxide precursor, a lithium source and a dopant are mixed and sintered, the sintering temperature is controlled to be 900-1100 DEG C, and the holding time is controlled to be 8-12 h.

5. The preparation method according to claim 1, characterized in that, The chemical formula of the lithium nickel manganese oxide positive electrode material to be modified is Li x Ni y Mn z O2, 0.5 < x < 0.55, 0.2 < y < 0.3, 0.7 < z < 0.8, y + z = 1.

6. The preparation method according to claim 5, characterized in that, After the holding is completed, crushing is performed and the crushed product is sieved through a 300-500 mesh sieve.

7. The preparation method according to claim 6, characterized in that, The doping element contained in the dopant is selected from at least one of Sr, Sb and Nb.

8. The preparation method according to claim 6, characterized in that, The lithium source is selected from at least one of lithium carbonate, lithium hydroxide and lithium oxide, and the molar ratio of the total amount of nickel and cobalt in the nickel-cobalt hydroxide precursor to the lithium content in the lithium source is controlled to be 1: (0.50-0.55).

9. The preparation method according to claim 6, characterized in that, The lithium nickel-manganese oxide positive electrode material is prepared by the preparation method.

10. A lithium nickel manganese oxide cathode material, characterized in that, The application further provides a lithium nickel-manganese oxide positive electrode material.

11. A positive electrode sheet characterized by comprising: The application further provides a positive electrode sheet.

12. A lithium battery, characterized by ​

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