High-cycle-performance lithium manganate positive electrode material for 5C-rate charge and discharge and preparation method of high-cycle-performance lithium manganate positive electrode material

Abstract

The invention discloses a lithium manganate positive electrode material with high cycle performance for 5C rate charge and discharge and a preparation method thereof, and belongs to the technical field of lithium ion battery positive electrode materials, the chemical formula of the lithium manganate positive electrode material is Li < 1 + x > Mn < 2-y-z > A < y > B < z > O < 4 >, A is one of Al, Mg, Nb, Ti and Zr, and B is one of La and Sc. The preparation method comprises the following steps: (1) weighing a manganese source, a lithium source, an A-containing compound and a B-containing compound, and mixing in a ball mill at a high speed to obtain precursor powder; (2) putting the obtained precursor powder into an alumina crucible, and sintering in a muffle furnace to obtain a sintered product; and (3) taking out the sintered product, placing the sintered product in a ball mill for secondary ball milling, and screening to obtain the lithium manganate positive electrode material. The lithium manganate positive electrode material prepared by the invention solves the problems of poor cycle performance, insufficient crystal structure stability, easy dissolution of manganese element and the like of the current lithium manganate positive electrode material under the condition of high rate (5C).

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery positive electrode materials, and particularly relates to a high-cycle performance lithium manganate positive electrode material for 5C rate charge and discharge and a preparation method thereof. Background Art

[0002] As one of the key technologies for modern energy storage, lithium-ion batteries have been widely researched and applied in the fields of energy conversion and storage. With the rapid development of portable electronic devices, electric vehicles, and large-scale energy storage systems, the market has placed higher demands on the energy density, cycle life, safety, and cost control of high-performance batteries.

[0003] Among numerous cathode materials, lithium cobalt oxide (LiCoO2) has long dominated the market due to its excellent electrochemical performance and mature commercial applications. However, its high raw material costs and poor thermal stability have limited its further promotion in power batteries and large-scale energy storage systems. In contrast, lithium manganese oxide (LiMn2O4) has the advantages of abundant raw materials, low cost, high safety, and environmental friendliness. In recent years, it has attracted widespread attention in cost-sensitive application scenarios such as low-end electric vehicles, power tools, and energy storage systems.

[0004] However, lithium manganese oxide still faces some key challenges in practical applications. For example, manganese ions (Mn 3+ ) dissolution, leading to electrolyte decomposition and capacity decay; at the same time, its crystal structure is susceptible to the Jahn-Teller effect, resulting in structural distortion and decreased cycling stability. These issues limit its application in high-energy-density and long-life battery systems. To improve the electrochemical performance of lithium manganese oxide, researchers have also proposed a variety of modification strategies, including anion and cation doping, surface coating, structural optimization, and morphology control.

[0005] Therefore, there is an urgent need to develop a new cathode material that can significantly improve the rate performance and cycle stability of lithium manganese oxide while maintaining its cost advantage, so as to meet the growing market demand and technological development trends. Summary of the Invention

[0006] In view of this, the present invention provides a high cycle performance lithium manganate positive electrode material for 5C rate charge and discharge and a preparation method thereof, which solves the problems of poor cycle performance, insufficient crystal structure stability and easy dissolution of manganese element in current lithium manganate positive electrode materials under high rate (5C) conditions. By introducing multiple metal elements for synergistic doping, the crystal structure of the material is effectively optimized, its structural stability and electrochemical performance are enhanced, and its cycle life and capacity retention rate at 5C rate are improved. At the same time, the preparation process provided by the present invention is simple, low-cost, has good industrial application prospects, can be applied to large-scale production, and provides strong support for the development of high-performance lithium-ion batteries.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention discloses a high cycle performance lithium manganate positive electrode material for 5C rate charge and discharge, wherein the chemical formula of the lithium manganate positive electrode material is Li 1+x Mn 2-y-z A y B z O4, wherein: 0.02≤x≤0.1, 0.01≤y≤0.06, 0.01≤z≤0.06, A is one of Al, Mg, Nb, Ti, and Zr, and B is one of La and Sc.

[0009] The present invention provides a method for preparing the above-mentioned lithium manganate positive electrode material with high cycle performance, comprising the following steps:

[0010] (1) weighing a manganese source, a lithium source, a compound containing A, and a compound containing B according to a set stoichiometric ratio, placing all the weighed raw materials in a ball mill, and mixing them at high speed until they are uniformly mixed to obtain a precursor powder;

[0011] (2) placing the precursor powder obtained in step (1) into an alumina crucible, placing the crucible into a muffle furnace, and sintering the crucible in an air atmosphere to obtain a sintered product;

[0012] (3) The sintered product of step (2) is taken out, placed in a ball mill for secondary ball milling, and then the powder is sieved using a standard sieve to obtain a lithium manganese oxide positive electrode material with uniform particle size distribution.

[0013] Preferably, in step (1), the parameters of the ball milling are: rotation speed 30-60 rpm, time 0.5-2 h.

[0014] Preferably, in step (1), the manganese source is Mn3O4, the lithium source is Li2CO3; the compound containing A is one of Al, Mg, Nb, Ti, and Zr oxides, and the compound containing B is one of La and Sc oxides.

[0015] Preferably, in step (1), the molar ratio of manganese, lithium, A, and B in the manganese source, lithium source, compound containing A, and compound containing B is (1.88-1.98): (1.02-1.1): (0.01-0.06): (0.01-0.06).

[0016] Preferably, in step (2), the sintering process in the muffle furnace is: starting from room temperature, first heating to 500-550°C at a heating rate of 1-5°C / min and keeping warm for 3-6 hours, then heating to 650-800°C at a heating rate of 3-5°C / min and keeping warm for 5-10 hours, and finally naturally cooling to room temperature.

[0017] Preferably, in step (3), the shape of the lithium manganate positive electrode material grains is spherical, and the D50 of the grains is 15 to 25 nm.

[0018] Preferably, in step (3), the tap density of the lithium manganate positive electrode material is 2.0 to 2.8 g / cm 3 The specific surface area of ​​the lithium manganate positive electrode material is 0.6 to 0.8 m 2 / g.

[0019] Preferably, in step (3), the parameters of the secondary ball milling are: rotation speed 30-60 rpm, time 0.5-2 h; the specification of the standard sieve is 300 mesh.

[0020] The present invention also provides the use of the above-mentioned lithium manganate positive electrode material with high cycle performance in the preparation of lithium ion batteries.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention solves the key technical difficulties of traditional spinel lithium manganese oxide (LiMn2O4) positive electrode materials during high-rate (5C) cycling, such as unstable crystal structure, severe manganese dissolution, and limited lithium ion diffusion, by combining a multi-element doping strategy with a gradient sintering process. The details are as follows.

[0023] (1) Crystal site control: The present invention selects one of Al, Mg, Nb, Ti, and Zr as the doping element A, and its cation (such as Al 3+ 、Ti 4+ ) has the same 3+ Similar or higher charge state, able to enter the octahedral 16d site to partially replace Mn 3+ , thereby reducing the unstable trivalent manganese ratio in the system and fundamentally inhibiting the occurrence of the Jahn-Teller effect; at the same time, these elements can also enhance the covalency of the Mn-O bond, improve the thermal stability and mechanical strength of the material; and, La and Sc as doping elements B have larger ionic radius (La3+ 0.103nm, Sc 3+ 0.0745nm), larger than Mn 3+ (0.0645nm), can occupy the 8a or 16c sites without destroying the original cubic spinel structure, and the La with a large ionic radius 3+ Sc 3+ Doping introduces a "spatial expansion" effect in the lattice, broadens the lithium ion transmission channel, reduces the diffusion resistance during lithium ion insertion / extraction, and improves the rate performance. At the same time, the introduction of doping elements also helps to improve the electronic conductivity of the material and improve the electrochemical kinetics.

[0024] (2) Jahn-Teller effect inhibition: Jahn-Teller effect is one of the key factors for the capacity decay of LiMn2O4. 3+ 3D 4 The local lattice stretching or compression caused by the electronic configuration. 4+ 、Nb 5+ ) can be partially oxidized to 3+ Converted to more stable Mn 4+ , fundamentally reducing the number of Jahn-Teller active centers; doping elements B (such as La 3+ ) stabilizes the lattice through the steric effect, alleviating the 3+ These synergistic effects significantly suppress the Jahn-Teller distortion, make the material structure more complete and stable, and improve the overall cycle performance.

[0025] (3) Manganese dissolution inhibition: In the electrolyte environment, especially in the presence of H+, Mn 3+ Easily reduced to Mn 2+ Doping elements A (such as Al, Ti) can promote the formation of stronger Mn-OM metal bridge bonds and enhance the binding force of Mn in the lattice; doping elements B (such as La, Sc) can form a stable interface passivation film on the surface of the material, reducing the direct contact between Mn and the electrolyte; at the same time, doping reduces the Mn 3+ ratio, reducing the possibility of its reduction, thereby significantly inhibiting the dissolution of manganese and extending battery life.

[0026] (4) The present invention adopts a two-stage gradient sintering process: the first stage (500-550°C for 3-6 hours) removes volatile impurities in the raw materials and initially forms a precursor phase; the second stage (650-800°C for 5-10 hours) achieves a full reaction between the doping elements and manganese and lithium, promoting lattice ordering; slow heating and reasonable holding time are conducive to uniform distribution of elements and avoid segregation; natural cooling can reduce residual stress and ensure grain integrity.

[0027] In summary, the present invention significantly improves the high-rate cycling performance and structural stability of LiMn2O4 materials through the synergistic effects of multiple levels, including crystal site regulation, Jahn-Teller effect suppression, manganese dissolution control, lithium ion diffusion path optimization, and sintering process improvement. It has good prospects for industrial application and is suitable for fields such as power batteries, energy storage systems, and high-power electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is an SEM image of the high cycle performance lithium manganate positive electrode material of Example 1 of the present invention;

[0029] Figure 2 The cycle performance diagram of lithium-ion batteries made of the lithium manganate positive electrode materials prepared in Examples 1 to 4 of the present invention and the lithium manganate positive electrode material prepared in Example 1 at a current density of 5C;

[0030] Figure 3 The capacity retention rate of lithium-ion batteries made of the lithium manganate positive electrode materials prepared in Examples 1 to 4 of the present invention and the lithium manganate positive electrode material prepared in Example 1 after 30 cycles at a current density of 5C. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0033] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0034] The present invention discloses a high cycle performance lithium manganate positive electrode material for 5C rate charge and discharge, the chemical formula of the lithium manganate positive electrode material is Li 1+x Mn 2-y-z A y Bz O4, wherein: 0.02≤x≤0.1, 0.01≤y≤0.06, 0.01≤z≤0.06, A is one of Al, Mg, Nb, Ti, and Zr, and B is one of La and Sc.

[0035] The present invention provides a method for preparing the above-mentioned lithium manganate positive electrode material with high cycle performance, comprising the following steps:

[0036] (1) According to the set stoichiometric ratio, a manganese source (Mn3O4), a lithium source (Li2CO3), a compound containing A (one of Al, Mg, Nb, Ti, and Zr oxides), and a compound containing B (one of La and Sc oxides) are weighed. All the weighed raw materials are placed in a ball mill and mixed at a speed of 30 to 60 rpm for 0.5 to 2 hours. The mixture is uniformly mixed to obtain a precursor powder.

[0037] (2) The precursor powder obtained in step (1) is loaded into an alumina crucible, placed in a muffle furnace, and sintered in an air atmosphere. The sintering process is as follows: starting from room temperature, first heating to 500-550°C at a heating rate of 1-5°C / min and keeping warm for 3-6 hours, then heating to 650-800°C at a heating rate of 3-5°C / min and keeping warm for 5-10 hours, and finally naturally cooling to room temperature; obtaining a sintered product.

[0038] (3) The sintered product of step (2) was taken out and placed in a ball mill for secondary ball milling. The mixture was mixed at a speed of 30 to 60 rpm for 0.5 to 2 hours, and then the powder was sieved using a 300-mesh standard sieve to obtain a lithium manganese oxide positive electrode material with uniform particle size distribution.

[0039] The molar ratio of manganese, lithium, A and B in the manganese source, lithium source, compound containing A and compound containing B is (1.88-1.98): (1.02-1.1): (0.01-0.06): (0.01-0.06).

[0040] The shape of the lithium manganate positive electrode material prepared above is spherical, the grain D50 is 15-25nm, and its tap density is 2.0-2.8g / cm 3 The specific surface area of ​​the lithium manganate positive electrode material is 0.6 to 0.8 m 2 / g.

[0041] The present invention also provides the use of the above-mentioned lithium manganate positive electrode material with high cycle performance in the preparation of lithium ion batteries.

[0042] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0043] Example 1

[0044] This embodiment has high cycle performance lithium manganate positive electrode material Li 1+x Mn 2-y-z Al y La z The preparation method of O4, the specific steps are as follows:

[0045] (1) Mn3O4, Li2CO3, Al2O3 and La2O3 were weighed according to the set stoichiometric ratio. The molar ratio of Mn, Li, Al and La in each raw material was 2:1.03:0.02:0.03. The above raw materials were placed in a ball mill and mixed at a speed of 50 rpm for 1 hour. After mixing, the precursor powder was obtained.

[0046] (2) The precursor powder obtained in step (1) is loaded into an alumina crucible, placed in a muffle furnace, and sintered in an air atmosphere. The sintering process is as follows: starting from room temperature, first heating to 500°C at a heating rate of 3°C / min and keeping warm for 5 hours, then heating to 700°C at a heating rate of 5°C / min and keeping warm for 10 hours, and finally naturally cooling to room temperature; obtaining a sintered product.

[0047] (3) The sintered product of step (2) was taken out and placed in a ball mill for secondary ball milling. The mixture was mixed at a speed of 50 rpm for 1.5 h, and then the powder was sieved using a 300-mesh standard sieve to obtain Li 1.03 Mn 1.975 Al 0.01 La 0.015 O4 lithium manganese oxide positive electrode material.

[0048] Figure 1 Li prepared in this example 1.03 Mn 1.975 Al 0.01 La 0.015 Scanning electron microscope (SEM) photos of O4 lithium manganese oxide positive electrode materials show that the material presents a spherical secondary particle morphology composed of primary grains, among which the larger spherical particles are actually aggregates formed by the aggregation of multiple small primary grains. Since these spherical particles are not single crystals, but are composed of multiple grains, they have a typical polycrystalline structure. This polycrystalline spherical structure not only enhances the mechanical strength of the material, enabling it to better withstand the stress caused by volume changes during the charge and discharge process, but also provides more active sites and lithium ion transmission channels, which helps to improve the electrochemical reaction kinetics of the material. In addition, the uniformly distributed primary grains are also conducive to the formation of a stable interface structure, further improving the cycle stability and rate performance of the material.

[0049] Example 2

[0050] This embodiment has high cycle performance lithium manganate positive electrode material Li 1+x Mn 2-y-z Al y La z The preparation method of O4, the specific steps are as follows:

[0051] (1) Mn3O4, Li2CO3, Al2O3 and La2O3 were weighed according to the set stoichiometric ratio. The molar ratio of Mn, Li, Al and La in each raw material was 2:1.03:0.02:0.02. The above raw materials were placed in a ball mill and mixed at a speed of 50 rpm for 1 hour. After mixing, the precursor powder was obtained.

[0052] (2) The precursor powder obtained in step (1) is loaded into an alumina crucible, placed in a muffle furnace, and sintered in an air atmosphere. The sintering process is as follows: starting from room temperature, first heating to 500°C at a heating rate of 3°C / min and keeping warm for 5 hours, then heating to 700°C at a heating rate of 5°C / min and keeping warm for 10 hours, and finally naturally cooling to room temperature; obtaining a sintered product.

[0053] (3) The sintered product of step (2) was taken out and placed in a ball mill for secondary ball milling. The mixture was mixed at a speed of 50 rpm for 1.5 h, and then the powder was sieved using a 300-mesh standard sieve to obtain Li 1.03 Mn 1.97 Al 0.01 La 0.01 O4 lithium manganese oxide positive electrode material.

[0054] Example 3

[0055] This embodiment has high cycle performance lithium manganate positive electrode material Li 1+x Mn 2-y-z Al y La z The preparation method of O4, the specific steps are as follows:

[0056] (1) Mn3O4, Li2CO3, Al2O3 and La2O3 were weighed according to the set stoichiometric ratio. The molar ratio of Mn, Li, Al and La in each raw material was 1.93:1.06:0.035:0.035. The above raw materials were placed in a ball mill and mixed at a speed of 30 rpm for 2 h. After being mixed evenly, a precursor powder was obtained.

[0057] (2) The precursor powder obtained in step (1) is loaded into an alumina crucible, placed in a muffle furnace, and sintered in an air atmosphere. The sintering process is as follows: starting from room temperature, first heating to 520°C at a heating rate of 2°C / min and keeping warm for 3 hours, then heating to 750°C at a heating rate of 3°C / min and keeping warm for 8 hours, and finally naturally cooling to room temperature; obtaining a sintered product.

[0058] (3) The sintered product of step (2) was taken out and placed in a ball mill for secondary ball milling. The mixture was mixed at a speed of 30 rpm for 2 h, and then the powder was sieved using a 300-mesh standard sieve to obtain Li 1.098 Mn 1.9274 Al 0.0363 La 0.0363 O4 lithium manganese oxide positive electrode material.

[0059] Example 4

[0060] This embodiment has high cycle performance lithium manganate positive electrode material Li 1+x Mn 2-y-z Al y La z The preparation method of O4, the specific steps are as follows:

[0061] (1) Mn3O4, Li2CO3, Al2O3 and La2O3 were weighed according to the set stoichiometric ratio. The molar ratio of Mn, Li, Al and La in each raw material was 1.90:1.06:0.04:0.05. The above raw materials were placed in a ball mill and mixed at a speed of 60 rpm for 0.5 h. After mixing, the precursor powder was obtained.

[0062] (2) The precursor powder obtained in step (1) is loaded into an alumina crucible, placed in a muffle furnace, and sintered in an air atmosphere. The sintering process is as follows: starting from room temperature, first heating to 550°C at a heating rate of 3°C / min and keeping warm for 6 hours, then heating to 800°C at a heating rate of 4°C / min and keeping warm for 5 hours, and finally naturally cooling to room temperature; obtaining a sintered product.

[0063] (3) The sintered product of step (2) was taken out and placed in a ball mill for secondary ball milling. The mixture was mixed at a speed of 60 rpm for 0.5 h, and then the powder was sieved using a 300-mesh standard sieve to obtain Li 1.116 Mn 1.9053 Al 0.0421 La 0.0526 O4 lithium manganese oxide positive electrode material.

[0064] Comparative Example 1

[0065] The preparation method of the lithium ion positive electrode material of this comparative example has the following specific steps:

[0066] (1) Weigh Mn3O4 and Li2CO according to the set stoichiometric ratio 3， The molar ratio of Mn, Li and Ni in the raw materials is 2:1.03. The above raw materials are placed in a ball mill and mixed at a speed of 50 rpm for 1 hour. After mixing evenly, a precursor powder is obtained.

[0067] (2) The precursor powder obtained in step (1) is loaded into an alumina crucible, placed in a muffle furnace, and sintered in an air atmosphere. The sintering process is as follows: starting from room temperature, first heating to 500°C at a heating rate of 3°C / min and keeping warm for 5 hours, then heating to 700°C at a heating rate of 5°C / min and keeping warm for 10 hours, and finally naturally cooling to room temperature; obtaining a sintered product.

[0068] (3) The sintered product of step (2) was taken out and placed in a ball mill for secondary ball milling. The mixture was mixed at a speed of 50 rpm for 1.5 h, and then the powder was sieved using a 300-mesh standard sieve to obtain Li 1.295 Mn 2.514 O4 lithium manganese oxide positive electrode material.

[0069] Performance testing:

[0070] In order to evaluate the electrochemical performance and cycle stability of the lithium manganate positive electrode materials prepared in Examples 1, 2, 3, 4 and Comparative Example 1 under high rate conditions, CR2032 button cells (half-cell system) were used for electrochemical testing. A metal lithium sheet was used as the counter electrode, a Celgard 2400 polypropylene microporous membrane was used as the diaphragm, the electrolyte was a mixed solvent system of 1M LiPF6 dissolved in EC:DMC (volume ratio 1:1), and the test environment temperature was set to 25°C; during the test, a constant current charge and discharge cycle was performed at a rate of 5C (1C = 120mA / g), and the voltage window was set to 3.0-4.3V (vs. Li / Li + ), the charge and discharge curves were recorded at the 1st, 10th, 20th and 30th cycles, and the following were calculated: the initial discharge specific capacity, the capacity retention rate (Cycle Capacity Retention), and the coulombic efficiency (Coulombic Efficiency); the capacity attenuation and structural stability of the materials during high-rate cycling were analyzed, and the electrochemical properties of the positive electrode materials prepared in Example 1, Example 2, Example 3, Example 4 and Comparative Example 1 are summarized in Table 1.

[0071] Table 1 Summary of performance of Examples 1 to 4 and Comparative Example 1

[0072]

[0073] As can be seen from the table, the first discharge specific capacity: Comparative Example 1 is the highest at 116.10 mAh / g, while the first capacity of Examples 1 to 4 is slightly lower, but the difference is not significant; the discharge specific capacity after 30 cycles: Comparative Example 1 significantly drops to 71.78 mAh / g, indicating that its cycle stability is poor, while the capacity changes of Examples 1 to 4 are small, all close to the first capacity, showing good cycle stability. In addition, the capacity retention rate of Comparative Example 1 is 61.82%, and the Coulomb efficiency is 96.04%, indicating that its capacity decay is serious after 30 cycles, there are many irreversible reactions or side reactions, the structure is unstable, and Jahn-Teller distortion and manganese dissolution are prone to occur; the capacity retention rates of Examples 1 to 4 are 99.54%, 98.92%, 98.21% and 99.16%, respectively, all higher than 98%, and all close to or exceeding 100%, indicating that doping with Al and La significantly improves the cycle stability of the material, effectively reduces side reactions, and improves energy conversion efficiency.

[0074] from Figure 2 and Figure 3 It can also be seen that the discharge capacity of Comparative Example 1 decreases rapidly with the number of cycles, dropping to 71.78 mAh / g at the 30th cycle, and the capacity retention rate is only 61.82%, indicating that the material structure of Comparative Example 1 is unstable and prone to irreversible reactions or side reactions; Examples 1 to 4 show excellent cycle stability in the discharge capacity throughout the cycle, and the capacity retention rate is also relatively stable. This shows that Comparative Example 1 is significantly inferior to Examples 1 to 4, and has serious structural instability problems under high-rate cycling; Examples 1 to 4 all show excellent cycle stability, high capacity retention, and almost no obvious attenuation of the discharge capacity.

[0075] The above is a detailed introduction to a high cycle performance lithium manganese oxide positive electrode material for 5C rate charge and discharge and a preparation method thereof disclosed in the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A high cycle performance lithium manganate positive electrode material for 5C rate charge and discharge, characterized in that: The chemical formula of the lithium manganate positive electrode material is Li 1+x Mn 2-y-z A y B z O4, wherein: 0.02≤x≤0.1, 0.01≤y≤0.06, 0.01≤z≤0.06, A is one of Al, Mg, Nb, Ti, and Zr, and B is one of La and Sc.

2. The method for preparing the lithium manganate positive electrode material with high cycle performance according to claim 1, characterized in that: The following steps are involved: (1) weighing a manganese source, a lithium source, a compound containing A, and a compound containing B according to a set stoichiometric ratio, placing all the weighed raw materials in a ball mill, and mixing them at high speed until they are uniformly mixed to obtain a precursor powder; (2) placing the precursor powder obtained in step (1) into an alumina crucible, placing the crucible into a muffle furnace, and sintering the crucible in an air atmosphere to obtain a sintered product; (3) The sintered product of step (2) is taken out, placed in a ball mill for secondary ball milling, and then the powder is sieved using a standard sieve to obtain a lithium manganese oxide positive electrode material with uniform particle size distribution.

3. The method for preparing a lithium manganate positive electrode material with high cycle performance according to claim 2, characterized in that: In step (1), the parameters of the ball milling are: rotation speed 30-60 rpm, time 0.5-2 h.

4. The method for preparing a lithium manganate positive electrode material with high cycle performance according to claim 2, characterized in that: In step (1), the manganese source is Mn3O4, the lithium source is Li2CO3; the compound containing A is one of Al, Mg, Nb, Ti, and Zr oxides, and the compound containing B is one of La and Sc oxides.

5. The method for preparing a lithium manganate positive electrode material with high cycle performance according to claim 4, characterized in that: In step (1), the molar ratio of manganese, lithium, A, and B in the manganese source, lithium source, compound containing A, and compound containing B is (1.88-1.98): (1.02-1.1): (0.01-0.06): (0.01～0.06)。 6. The method for preparing a lithium manganate positive electrode material with high cycle performance according to claim 2, characterized in that: In step (2), the sintering process in the muffle furnace is as follows: starting from room temperature, first heating to 500-550°C at a heating rate of 1-5°C / min and keeping warm for 3-6 hours, then heating to 650-800°C at a heating rate of 3-5°C / min and keeping warm for 5-10 hours, and finally naturally cooling to room temperature.

7. The method for preparing a lithium manganate positive electrode material with high cycle performance according to claim 2, characterized in that: In step (3), the shape of the lithium manganate positive electrode material grains is spherical, and the grain D50 is 15 to 25 nm.

8. The method for preparing a lithium manganate positive electrode material with high cycle performance according to claim 7, characterized in that: In step (3), the tap density of the lithium manganate positive electrode material is 2.0 to 2.8 g / cm 3 The specific surface area of ​​the lithium manganate positive electrode material is 0.6 to 0.8 m 2 / g.

9. The method for preparing a lithium manganate positive electrode material with high cycle performance according to claim 2, characterized in that: In step (3), the parameters of the secondary ball milling are: rotation speed 30-60 rpm, time 0.5-2 h; the specification of the standard sieve is 300 mesh.

10. Use of the lithium manganate positive electrode material with high cycle performance according to claim 1 in the preparation of lithium ion batteries.

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