Method for preparing lithium manganate through composite doping modification, lithium manganate positive electrode material and lithium ion battery

Abstract

The invention discloses a method for preparing lithium manganate through composite doping modification, which comprises the following steps: mixing and ball-milling: mixing raw materials manganese dioxide and lithium carbonate according to a Li / Mn molar ratio of 0.52-0.56, and adding 0.4-0.5% by weight of aluminum oxide, 0.35-0.45% by weight of niobium oxide and 0.35-0.45% by weight of titanium oxide as additives; mixing the materials and grinding balls together, and carrying out mixed material ball milling for 2-3 hours; the temperature is increased to 200-300 DEG C at the speed of 3-5 DEG C / min and kept for 1-3 h, then the temperature is increased to 600-650 DEG C at the speed of 3-5 DEG C / min and kept for 1-3 h, and finally the temperature is increased to 750-780 DEG C at the speed of 3-5 DEG C / min And cooling the material subjected to gradient sintering to normal temperature along with the furnace, crushing, and screening by a screen to obtain a lithium manganate finished product. Performance optimization and cost reduction of the product are realized by optimizing the Li / Mn molar ratio and a gradient sintering process and adding different types of additives and doping amounts.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a method for preparing lithium manganese oxide through composite doping modification, lithium manganese oxide cathode material, and lithium-ion battery. Background Technology

[0002] In the field of lithium battery technology, lithium manganese oxide (LiMn2O4) has become an important cathode material in lithium batteries and energy storage due to its low cost, high safety and environmental friendliness.

[0003] During the charging and discharging process of lithium manganese oxide, especially under deep discharge (low voltage) conditions, Mn 3+ Excessive concentration can cause Jahn-Teller distortion (the crystal structure is twisted from cubic to tetragonal), which leads to structural damage, increased internal stress, and rapid capacity decay.

[0004] Lithium manganese oxide (LiMnO), as a cathode material for lithium-ion batteries, is significantly affected by its preparation method, which directly impacts its crystal structure, particle morphology, electrochemical performance, and stability. Existing technologies primarily employ high-temperature solid-state methods, sol-gel methods, co-precipitation methods, and hydrothermal / solvothermal methods. Among these, the high-temperature solid-state method is commonly used in industrial production due to its relative simplicity and ease of industrialization. In the high-temperature solid-state method, improving the structural stability and cycle performance of LiMnO through metal ion doping is widely accepted. However, balancing production costs with LiMnO performance, optimizing the Li / Mn molar ratio, and employing sintering and composite doping processes to prepare cost-effective LiMnO materials while reducing production costs and energy consumption remain urgent challenges for the industry. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing lithium manganese oxide through composite doping modification, a lithium manganese oxide cathode material, and a lithium-ion battery. By using composite doping modification technology, the crystal structure stability of lithium manganese oxide is optimized, structural degradation during cycling is reduced, cycling stability is improved, the performance of lithium manganese oxide cathode material is enhanced, and the production cost of lithium manganese oxide is reduced.

[0006] To solve the above technical problems, the embodiments of the present invention provide a technical solution as follows: A method for preparing lithium manganese oxide by composite doping modification, comprising the following steps: S1. Mixing and ball milling: Electrolytic manganese dioxide and lithium carbonate are mixed at a Li / Mn molar ratio of 0.52 to 0.56. Based on the total weight of the two, 0.4% to 0.5% aluminum oxide, 0.35% to 0.45% niobium oxide, and 0.35% to 0.45% titanium oxide are added as additives, accounting for 0.4% to 0.5% of the base weight; the electrolytic manganese dioxide, lithium carbonate, additives, and grinding balls are mixed together and ball milled for 2 to 3 hours; S2. Gradient sintering: The ball-milled material is heated to 200 to 300°C at a rate of 3 to 5°C / min and held for 1 to 3 hours, then heated to 600 to 650°C at a rate of 3 to 5°C / min and held for 1 to 3 hours, and finally heated to 750 to 780°C at a rate of 3 to 5°C / min and held for 18 to 22 hours; S3. Crushing and sieving: After gradient sintering, the material is cooled to room temperature in the furnace, crushed, and then sieved through a 200-300 mesh screen to obtain the finished lithium manganese oxide product.

[0007] Furthermore, the aluminum oxide is Al2O3, the niobium oxide is Nb2O5, and the titanium oxide is TiO2.

[0008] Furthermore, the amount of additives added is as follows: Al2O3 accounts for 0.45% of the base weight, Nb2O5 accounts for 0.40% of the base weight, and TiO2 accounts for 0.40% of the base weight.

[0009] Furthermore, the Li / Mn molar ratio in step S1 is 0.535.

[0010] Furthermore, the parameters for gradient sintering in step S2 are as follows: First stage: heating to 250℃ at 3℃ / min and holding for 2 hours; Second stage: heating to 630℃ at 3℃ / min and holding for 2 hours; Third stage: heating to 770℃ at 3℃ / min and holding for 20 hours.

[0011] Furthermore, the grinding balls in step S1 include balls of various sizes, namely large balls with a diameter of 30±2mm, medium balls with a diameter of 20±2mm, and small balls with a diameter of 15±2mm. The weight ratio of the three types of balls is: large ball: medium ball: small ball = 2:1:1.

[0012] Furthermore, the grinding ball is a zirconia ball or a polyurethane ball.

[0013] Furthermore, in step S3, a 200-mesh vibrating screen is used for sieving.

[0014] To address the aforementioned technical problems, the present invention also provides a lithium manganese oxide cathode material, prepared by any of the methods described above.

[0015] To address the aforementioned technical problems, the present invention also provides a lithium-ion battery comprising the aforementioned lithium manganese oxide cathode material.

[0016] The present invention provides a method for preparing lithium manganese oxide through composite doping modification. This method employs a high-temperature solid-state approach, optimizing the Li / Mn molar ratio and gradient sintering process, and supplementing this with different types of additives and varying doping amounts to achieve product performance optimization and cost reduction. Through the synergistic effect of aluminum oxide, niobium oxide, and titanium-containing oxide additives, the crystal structure stability of lithium manganese oxide is optimized, manganese dissolution and Jahn-Teller distortion are suppressed, structural degradation during cycling is reduced, and cycling stability is improved. Specifically, the doping of aluminum oxide allows aluminum ions to replace Mn. 3+ Ions, reducing Mn 3+ It triggers a significant spontaneous disproportionation reaction, increasing Li + The additives improve transport rate and prevent SEI (solid electrolyte interface) damage. Doping with titanium oxide forms a titanium oxide coating after sintering, preventing direct contact with hydrofluoric acid and reducing side reactions at the cathode-electrolyte interface. Doping with niobium oxide increases the average oxidation state of manganese to +3.5 or higher, suppressing the Jahn-Teller effect and providing a larger MO bond energy (M represents the metal's oxidation state), thus enhancing crystal structure stability. Through the interaction of these additives with electrolytic manganese dioxide and lithium carbonate, structural distortion of lithium manganese oxide can be significantly suppressed, reducing structural degradation during cycling and improving cycle stability. Meanwhile, by optimizing the Li / Mn molar ratio and using more cost-effective aluminum oxides, the use of niobium oxides is reduced, which helps lower the production cost of lithium manganese oxide. Through a gradient sintering process, volatile components are removed in stages, avoiding structural defects. For example, the raw material lithium carbonate (Li2CO3) decomposes at high temperatures to produce CO2 gas; if the temperature rises too quickly, the violent release of gas can lead to the formation of pores or cracks inside the particles. Rapid grain growth at high temperatures can also prevent uneven particle size, allowing for controlled grain growth and optimized crystallinity. This results in more thorough and uniform sintering of the material, preventing segregation of dopant elements caused by excessively rapid heating. In particular, by using a specific ratio of large, medium, and small grinding balls and mixing the grinding balls with the raw material in a single batch, the process for preparing lithium manganese oxide is simplified. Compared to single-size ball milling, the required mixing uniformity and particle size can be achieved more quickly, shortening the milling time and improving milling efficiency, which is beneficial for improving the uniformity of the mixing of trace additives. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings represent similar elements. Unless otherwise stated, the figures in the drawings do not constitute a limitation on scale.

[0018] Figure 1 This is a process flow diagram of a composite doping modification process for preparing lithium manganese oxide in an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the various embodiments of this invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this invention to facilitate a better understanding of this application. However, the technical solutions claimed in the claims of this application can be implemented even without these technical details and with various variations and modifications based on the following embodiments.

[0020] like Figure 1 As shown, this invention relates to a method for preparing composite doped lithium manganese oxide cathode material based on EMD (electrolytic manganese dioxide). The preparation method adopts a high-temperature solid-state method and prepares high-performance lithium manganese oxide material by controlling parameters such as raw material ratio, doping elements, and sintering process.

[0021] In one embodiment of the present invention, a method for preparing lithium manganese oxide by composite doping modification is disclosed, comprising the following steps: S1. Mixing and ball milling: First, the raw materials are mixed and ball milled, wherein the grinding balls used in the ball mill include large balls, medium balls and small balls, the diameter of the large balls is 30±2mm, the diameter of the medium balls is 20±2mm, and the diameter of the small balls is 15±2mm. The weight ratio of the three types of grinding balls is: large balls: medium balls: small balls = 2:1:1. Preferably, the grinding balls are zirconia balls or polyurethane balls. Electrolytic manganese dioxide (EMD) and lithium carbonate (Li2CO3) were prepared with a Li / Mn molar ratio of 0.52 to 0.56. The sum of the weights of the prepared EMD and lithium carbonate was used as the base weight. Additives were added according to the weight percentage of the base weight. The additives included: aluminum (Al) oxides, with a mass percentage of 0.4% to 0.5% relative to the base weight; niobium (Nb) oxides, with a mass percentage of 0.35% to 0.45% relative to the base weight; and titanium (Ti) oxides, with a mass percentage of 0.35% to 0.45% relative to the base weight. S1. Ball milling: Mix the above-mentioned grinding balls, electrolytic manganese dioxide, lithium carbonate and additives and ball mill for 2-3 hours to ensure uniform mixing of raw materials and optimize particle size distribution; S2. Gradient sintering: Put the mixed ball-milled material into a sintering furnace for sintering. During the sintering process, heat the material to 200-300℃ at a heating rate of 3-5℃ / min and hold for 1-3 hours; then heat the material to 600-650℃ at a heating rate of 3-5℃ / min and hold for 1-3 hours; then heat the material to 750-780℃ at a heating rate of 3-5℃ / min and hold for 18-22 hours; S3. Crushing and sieving: Cool the material after gradient sintering to room temperature with the furnace, crush it and sieve it to obtain the finished lithium manganese oxide product.

[0022] During the ball milling process, the powerful impact of large balls breaks up agglomerates and coarse particles, while the dense friction of small balls achieves fine grinding and uniform dispersion. Medium balls facilitate energy transfer and optimize filling. The synergistic effect of these three components achieves the best mixing effect. This combination can achieve the required mixing uniformity and particle size requirements faster than single-size ball milling, shortening the milling time and improving milling efficiency. In particular, for the dispersion of trace additives, the dense friction of small balls makes the material composition highly uniform, increasing the uniformity of mixing.

[0023] Doping with aluminum oxides allows aluminum ions to replace Mn. 3+ This leads to a more stable crystal structure, preventing / reducing Mn 3+ It induces a significant spontaneous disproportionation reaction, preventing the formation of soluble spinel Mn. 2+ (Mn 3+ )2O4 and the insoluble phase Li (Li 1 / 3 Mn 5 / 3 Irreversible oxidation of O4. Prevents / reduces the deposition of partially dissolved manganese ions on the negative electrode, improving Li... + Transport rate and prevention of SEI (solid electrolyte interface) damage.

[0024] By doping with titanium oxide, a titanium oxide coating is formed after sintering, which avoids direct contact with hydrofluoric acid, prevents direct reaction between the electrolyte and the surface of the active material, and reduces side reactions at the interface between the positive electrode and the electrolyte.

[0025] Through doping with niobium oxide, Nb 5+ The ion has a high valence state and stable chemical properties, when Nb 5+ When doped into the LiMn2O4 lattice, the average oxidation state of manganese can be increased to +3.5 and above, suppressing the Jahn-Teller effect, exhibiting a large MO bond energy (M represents the oxidation state of the metal), enhancing the stability of the crystal structure, reducing structural degradation during cycling, and improving cycling stability.

[0026] One embodiment involves a method for preparing lithium manganese oxide through composite doping modification. Samples numbered 1-8 are prepared using electrolytic manganese dioxide, lithium manganese oxide, and various additives. Electrolytic manganese dioxide and lithium carbonate are prepared at a Li / Mn molar ratio of 0.52–0.56. The sum of the weights of the electrolytic manganese dioxide and lithium carbonate is the base weight. Additives are added as a percentage of the base weight, including 0.4%–0.5% alumina, 0.35%–0.45% titanium dioxide, and 0.35%–0.45% niobium oxide relative to the base weight. In sample 1, the alumina added is 0.40% of the base weight, and the niobium oxide added is 0.35% of the base weight. In sample 1, the addition weight of titanium oxide was 0.35% of the base weight; in sample 2, the addition weight of alumina was 0.45% of the base weight, the addition weight of niobium oxide was 0.40% of the base weight, and the addition weight of titanium oxide was 0.40% of the base weight; in sample 3, the addition weight of alumina was 0.50% of the base weight, the addition weight of niobium oxide was 0.45% of the base weight, and the addition weight of titanium oxide was 0.45% of the base weight; in samples 4-8, the addition weight of alumina was 0.45% of the base weight, the addition weight of niobium oxide was 0.40% of the base weight, and the addition weight of titanium oxide was 0.40% of the base weight; the raw material composition of samples 1-8 is shown in Table 1, the lithium manganese oxide composition table.

[0027] Table 1 Lithium Manganate Ingredients List

[0028] Zirconia balls were selected as grinding balls and mixed with the above raw materials. The mixture was then ball-milled for 2-3 hours to ensure uniform mixing and fine, concentrated particle size. The ball-milled raw materials were then placed in a sintering furnace for sintering using a gradient sintering method. The temperature was increased to 200-300℃ at a rate of 3-5℃ / min and held for 1-3 hours; then increased to 600-650℃ at a rate of 3-5℃ / min and held for 1-3 hours; then increased to 750-780℃ at a rate of 3-5℃ / min and held for 18-22 hours. Subsequently, the furnace was cooled to room temperature, and the product was pulverized and sieved using a 200-300 mesh vibrating screen to obtain the finished lithium manganese oxide product. Gradient sintering removes volatile components in stages, avoiding structural defects. For example, when lithium carbonate decomposes at high temperatures to produce CO2 gas, rapid heating can cause the violent release of gas, leading to the formation of pores or cracks inside the particles. It also prevents rapid grain growth at high temperatures from causing uneven particle size, allowing for controlled grain growth and optimized crystallinity. Furthermore, it ensures that each dopant element diffuses to the lattice sites at different temperatures, preventing segregation caused by rapid heating, resulting in more thorough and uniform sintering of the material.

[0029] The obtained lithium manganese oxide product was tested for physical and electrochemical properties. The main physical property test results are shown in Table 2 - Physical Property Test Record Table. The lithium manganese oxide was assembled into a button cell and its electrochemical performance was tested. The electrochemical performance test results at 25℃ are shown in Table 3 - 25℃ Button Cell Cycling Performance Test Record Table, and the electrochemical performance test results at 45℃ are shown in Table 4 - 45℃ Button Cell Cycling Performance Test Record Table.

[0030] Table 2 Physical Performance Test Record Sheet

[0031] As shown in Table 2, the TD tap density of the lithium manganese oxide finished material provided by this invention is ≥1.91 g / cm³. 3 Specific surface area less than 0.6m² 2 / g, D50 particle size is concentrated in 8-16μm, with good particle size concentration, and all indicators meet industry standards.

[0032] Table 3. 25℃ Button Cycle Performance Test Record Sheet

[0033] As can be seen from the data in Table 3, the lithium manganese oxide provided by this invention, as a positive electrode material, exhibits excellent electrochemical performance under coin cell testing at room temperature (25℃), with a 0.1C discharge capacity greater than 116 mAh / g, a 1C discharge capacity greater than 114 mAh / g, and a capacity decay rate of less than 2.9% after 100 cycles of 1C / 1C cycling.

[0034] Table 4. 45℃ Button Cycle Performance Test Record

[0035] As can be seen from the data in Table 4, the lithium manganese oxide provided by this invention, when used as a positive electrode material in a high-temperature 45°C coin cell test, exhibits a 0.2C discharge capacity greater than 116 mAh / g, a 1C discharge capacity greater than 115 mAh / g, and a 1C / 1C 100-cycle charge-discharge decay rate of less than 5.5%, demonstrating excellent electrochemical performance.

[0036] One embodiment involves a method for preparing lithium manganese oxide through composite doping modification, with sample 2 selected for scale-up production testing. First, electrolytic manganese dioxide and lithium carbonate are prepared at a Li / Mn molar ratio of 0.535. 200 kg of electrolytic manganese dioxide (92% purity) and 41.83 kg of lithium carbonate are added. Based on the base weights of the electrolytic manganese dioxide and lithium carbonate, 0.45% alumina, 0.40% niobium oxide, and 0.40% titanium oxide are added respectively for ball milling for 2 hours. The mixed and ball-milled raw materials are then subjected to gradient sintering in a sintering furnace. The first gradient sintering involves heating to 250°C at a rate of 3°C / min and holding for 2 hours; then heating to 630°C at a rate of 3°C / min and holding for 2 hours to complete the second gradient sintering; finally, a third gradient sintering is performed, heating to 770°C at a rate of 3°C / min and holding for 20 hours. After cooling to room temperature in the furnace, the product inside the furnace was pulverized and sieved through a 200-mesh vibrating sieve to obtain the lithium manganese oxide product. Samples of the lithium manganese oxide product were taken to make button cells for electrochemical performance testing. The test results are shown in Tables 5 and 6.

[0037] Table 5. Record of 25℃ Button Cycle Performance Test of Magnified Samples

[0038] Table 6. Record of Electrode Cycling Performance Test of Enlarged Samples at 45℃

[0039] The data in Tables 5 and 6 show that the scaled-up sample exhibits better cycle performance than the control sample 2 at both room temperature (25℃) and high temperature (45℃). Its capacity and overall charge-discharge cycle performance are better, and all indicators have met the expected targets, making it suitable for batch scale-up on the production line.

[0040] One embodiment involves a lithium manganese oxide cathode material, prepared by any of the above-mentioned composite doping modification methods for preparing lithium manganese oxide. Through experimental and production verification, the tap density of the lithium manganese oxide cathode material is ≥1.91 g / cm³. 3 Specific surface area < 0.6 m² 2 / g; D50 particle size distribution is 8-16μm; at 25℃, 0.1C discharge capacity >116mAh / g, 1C discharge capacity >114mAh / g, and capacity decay rate after 100 cycles of 1C / 1C <2.9%; at 45℃, 0.2C discharge capacity >116mAh / g, 1C discharge capacity >115mAh / g, and capacity decay rate after 100 cycles of 1C / 1C <5.5%.

[0041] Another embodiment of the present invention relates to a lithium-ion battery, comprising a lithium manganese oxide cathode material prepared by any of the above-described methods for preparing lithium manganese oxide through composite doping modification.

[0042] The present invention provides a method for preparing lithium manganese oxide through composite doping modification. This method employs a high-temperature solid-state approach, optimizing the Li / Mn molar ratio and gradient sintering process, and supplementing this with different types of additives and varying doping amounts to achieve product performance optimization and cost reduction. Through the synergistic effect of aluminum oxide, niobium oxide, and titanium-containing oxide additives, the crystal structure stability of lithium manganese oxide is optimized, manganese dissolution and Jahn-Teller distortion are suppressed, structural degradation during cycling is reduced, and cycling stability is improved. Specifically, the doping of aluminum oxide allows aluminum ions to replace Mn. 3+ Ions, reducing Mn 3+ It triggers a significant spontaneous disproportionation reaction, increasing Li + The additives improve transport rate and prevent SEI (solid electrolyte interface) damage. Doping with titanium oxide forms a titanium oxide coating after sintering, preventing direct contact with hydrofluoric acid and reducing side reactions at the cathode-electrolyte interface. Doping with niobium oxide increases the average oxidation state of manganese to +3.5 or higher, suppressing the Jahn-Teller effect and providing a larger MO bond energy (M represents the metal's oxidation state), thus enhancing crystal structure stability. Through the interaction of these additives with electrolytic manganese dioxide and lithium carbonate, structural distortion of lithium manganese oxide can be significantly suppressed, reducing structural degradation during cycling and improving cycle stability. Meanwhile, by optimizing the Li / Mn molar ratio and using more cost-effective aluminum oxides, the use of niobium oxides is reduced, which helps lower the production cost of lithium manganese oxide. Through a gradient sintering process, volatile components are removed in stages, avoiding structural defects. For example, the raw material lithium carbonate (Li2CO3) decomposes at high temperatures to produce CO2 gas; if the temperature rises too quickly, the violent release of gas can lead to the formation of pores or cracks inside the particles. Rapid grain growth at high temperatures can also prevent uneven particle size, allowing for controlled grain growth and optimized crystallinity. This results in more thorough and uniform sintering of the material, preventing segregation of dopant elements caused by excessively rapid heating. In particular, by using a specific ratio of large, medium, and small grinding balls and mixing the grinding balls with the raw material in a single batch, the process for preparing lithium manganese oxide is simplified. Compared to single-size ball milling, the required mixing uniformity and particle size can be achieved more quickly, shortening the milling time and improving milling efficiency, which is beneficial for improving the uniformity of the mixing of trace additives.

[0043] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be defined by the claims.

Claims

1. A method for preparing lithium manganese oxide through composite doping modification, characterized in that, Includes the following steps: S1. Mixing and ball milling: Electrolytic manganese dioxide and lithium carbonate are mixed at a Li / Mn molar ratio of 0.52 to 0.

56. Based on the total weight of the two, 0.4% to 0.5% aluminum oxide, 0.35% to 0.45% niobium oxide, and 0.35% to 0.45% titanium oxide are added as additives. The electrolytic manganese dioxide, lithium carbonate, additives, and grinding balls are then mixed and ball milled for 2 to 3 hours. S2. Gradient sintering: The ball-milled material is heated to 200-300℃ at a rate of 3-5℃ / min and held for 1-3 hours, then heated to 600-650℃ at a rate of 3-5℃ / min and held for 1-3 hours, and finally heated to 750-780℃ at a rate of 3-5℃ / min and held for 18-22 hours. S3. Crushing and sieving: After gradient sintering, the material is cooled to room temperature in the furnace, crushed, and then sieved to obtain the finished lithium manganese oxide product.

2. The method for preparing lithium manganese oxide by composite doping modification according to claim 1, characterized in that, The aluminum oxide is Al2O3, the niobium oxide is Nb2O5, and the titanium oxide is TiO2.

3. The method for preparing lithium manganese oxide by composite doping modification according to claim 2, characterized in that, The additive amounts are: Al2O3 accounts for 0.45% of the base weight, Nb2O5 accounts for 0.40% of the base weight, and TiO2 accounts for 0.40% of the base weight.

4. The method for preparing lithium manganese oxide by composite doping modification according to claim 1, characterized in that, The Li / Mn molar ratio mentioned in step S1 is 0.

535.

5. The method for preparing lithium manganese oxide by composite doping modification according to claim 1, characterized in that, The parameters for gradient sintering in step S2 are: First stage: Increase the temperature to 250℃ at 3℃ / min and hold for 2 hours; Second stage: Increase the temperature to 630℃ at 3℃ / min and hold for 2 hours; The third stage: Increase the temperature to 770℃ at a rate of 3℃ / min and hold for 20 hours.

6. The method for preparing lithium manganese oxide by composite doping modification according to claim 1, characterized in that, The grinding balls in step S1 include balls of various sizes, including large balls with a diameter of 30±2mm, medium balls with a diameter of 20±2mm, and small balls with a diameter of 15±2mm. The weight ratio of the three types of balls is: large ball: medium ball: small ball = 2:1:

1.

7. The method for preparing lithium manganese oxide by composite doping modification according to claim 1, characterized in that, The grinding balls are zirconia balls or polyurethane balls.

8. The method for preparing lithium manganese oxide by composite doping modification according to claim 1, characterized in that, In step S3, a 200-300 mesh vibrating screen is used for sieving.

9. A lithium manganese oxide cathode material, characterized in that: It is prepared by the method described in any one of claims 1-8.

10. A lithium-ion battery, characterized in that, It includes the lithium manganese oxide cathode material as described in claim 9.

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