Lithium-rich manganese-based positive electrode material and preparation method thereof

Abstract

The invention provides a lithium-rich manganese-based positive electrode material, the lithium-rich manganese-based positive electrode material comprises a matrix and a coating layer on the surface of the matrix, in a powder X-ray diffraction pattern of the lithium-rich manganese-based positive electrode material, a peak of cerium oxide exists at a diffraction angle of (28 + / -0.2) degrees, and a peak of cobalt oxide exists at a diffraction angle of (54 + / -0.2) degrees; the invention further discloses a preparation method of the lithium-rich manganese-based positive electrode material, compared with the prior art, the coated and modified lithium-rich manganese-based positive electrode material provided by the invention takes the compound with the specific general formula as a matrix, and a composite coating layer with stable chemical properties is obtained through composite coating of nano cobalt oxide and nano cerium oxide; due to the synergistic effect of cobalt and cerium oxide, the specific surface area of the lithium-rich manganese-based material is reduced, the binding force with the surface of the material is increased, and the problem that a coating layer falls off and fails is solved.

Description

Technical Field

[0001] This invention relates to the field of electrode technology, specifically to a lithium-rich manganese-based cathode material and its preparation method. Background Technology

[0002] The kinetic performance of lithium-rich cathodes is significantly lower than that of ternary cathodes. Therefore, high-capacity, secondary spherical lithium-rich cathodes need to have higher porosity than ternary cathodes to shorten the lithium migration distance. This design inevitably results in a higher specific surface area, which is detrimental to interfacial stability. Under high voltage, this can easily lead to severe interfacial side reactions, causing deterioration and decomposition of the electrode and electrolyte interfaces, ultimately resulting in battery failure. Therefore, it is crucial to reduce the specific surface area of ​​lithium-rich cathodes while maintaining high capacity or even further enhancing its capacity.

[0003] Currently, several solutions have been proposed to address the cycling and rate performance issues of lithium-rich manganese-based materials. One common approach is to improve material performance through surface coating, synthetic doping, and other methods.

[0004] However, existing technologies have some limitations or drawbacks. First, doping methods often introduce additional costs and process complexity. Second, due to the instability and poor ionic conductivity of common coatings, it is difficult to fully realize the material's capacity. Therefore, certain challenges remain in practical applications. Thus, a new method is needed to improve the cycling and rate performance of materials while ensuring full capacity utilization. Currently, commonly used coating processes involve coating the material surface with a layer of cerium oxide. The cerium oxide coating reduces the specific surface area of ​​the material to some extent, improving capacity utilization. However, because the ionic radius of cerium oxide differs significantly from that of the matrix material, the coating frequently detaches, and the coating process is not very stable.

[0005] In summary, existing solutions to the poor cycle performance and rate performance of lithium-rich manganese-based materials have certain limitations. Therefore, a new method is needed to improve the rate performance of the material while ensuring full capacity utilization. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a lithium-rich manganese-based cathode material and its preparation method that are synergistically coated and modified with cobalt oxide and cerium oxide, thereby overcoming the shortcomings of the prior art.

[0007] The present invention provides a lithium-rich manganese-based cathode material, the lithium-rich manganese-based cathode material comprising a matrix and a coating layer on the surface of the matrix, wherein the powder X-ray diffraction pattern of the lithium-rich manganese-based cathode material has a cerium oxide peak at a diffraction angle of (28±0.2)° and a cobalt oxide peak at a diffraction angle of (54±0.2)°.

[0008] Compared with existing technologies, this invention employs a matrix and a coating layer. Testing has shown that cerium-based cobalt oxide with an interface structure is obtained in the lithium-rich manganese-based cathode material. The main advantages are: the cobalt oxide coating can enhance lithium-ion transport to a certain extent, thereby improving material performance. Furthermore, the ionic radius of cobalt oxide is between that of the cathode material and cerium oxide, so cobalt oxide can be used as a transition layer to combine with the cerium oxide coating. This stabilizes the cerium oxide coating while also achieving the desired effects of cobalt oxide coating, resulting in cerium-based cobalt oxide with an interface structure. This interface effect, due to strong bonding and synergistic interactions, can provide more oxygen vacancies as active sites than a single oxide component, promoting electron conduction and charge transfer. This invention employs a co-coating of cobalt and cerium oxide on the surface of the lithium-rich manganese-based material. This technique, due to the synergistic effect of cobalt and cerium oxide, reduces the specific surface area of ​​the lithium-rich manganese-based material and increases the adhesion to the material surface, avoiding the problem of coating layer detachment and failure. Moreover, the stable coating layer avoids direct contact between the material and the electrolyte, thus significantly improving the problem of poor cycle stability caused by electrolyte decomposition. Furthermore, due to the synergistic effect of cobalt and cerium oxide, the coating layer has extremely low lithium-ion transport resistance, which is more conducive to the utilization of the material's capacity.

[0009] In one possible implementation, the coating layer accounts for 0.1-1% of the mass percentage of the lithium-rich manganese-based cathode material, and the molar ratio of cobalt to cerium in the coating layer is 1:(1-5).

[0010] Compared with existing technologies, the coating layer of the present invention, with a mass percentage of 0.1-1%, ensures that the coating material can form a uniform and continuous coating layer on the surface of the substrate powder, without being too thick or too thin. If the coating layer is too thick (more than 1%), it may hinder lithium-ion transport and reduce the performance of the electrode material. Appropriate coating can effectively reduce the occurrence of side reactions while maintaining good ion conductivity. Appropriate amounts of cobalt oxide and cerium oxide coating layers can form a stable interface between the substrate and the electrolyte, reducing unnecessary side reactions and improving the cycle stability and safety of the battery. Furthermore, due to the synergistic effect of cobalt oxide and cerium oxide, more oxygen vacancies can be generated in the coating layer. These vacancies, as active sites, can promote electron conduction and charge transfer, thereby improving the overall performance of the battery.

[0011] Meanwhile, when the molar ratio of Co to Ce is 1:(1-5), the two metal ions can form a uniform and stable interface structure. This structure can effectively prevent direct contact between the electrolyte and the matrix material, reduce the occurrence of side reactions, and thus improve the cycle stability and safety of the battery. At the same time, the synergistic effect of Co and Ce can generate more oxygen vacancies in the coating layer. These vacancies serve as active sites, promoting electron conduction and lithium-ion transport, thereby improving the electrochemical performance of the material.

[0012] In one possible implementation, the molecular formula of the matrix is: Li 1+a Ni x Mn y O2, where 0.1≤a≤0.5, 0≤x≤0.3, 0≤z≤0.9, a+x+y=1. Compared with existing technologies, lithium-rich manganese-based materials, due to their high capacity characteristics, and by further adjusting the Ni / Mn ratio, can optimize the voltage plateau and energy density of the material, achieve high energy density, excellent chemical and structural stability, flexible performance adjustment, and significant cost-effectiveness. This provides a high-performance, safe, reliable, and economical lithium battery cathode material, particularly suitable for applications in electric vehicles and energy storage systems where high energy density and cycle life are required.

[0013] Specifically, the specific surface area of ​​the lithium-rich manganese-based cathode material is 0.73-0.88 cm². 2 / g.

[0014] When a cobalt oxide or cerium oxide interface layer is formed on the surface of a lithium-rich manganese-based cathode material, it is actually adding a layer of material to the particle surface. This layer of material covers the original outer surface of the cathode material, causing some of the originally exposed active sites to be blocked. The presence of the coating layer changes the microstructure of the material, which may make the particles more compact, reduce the total porosity of the material, and thus reduce the overall specific surface area.

[0015] The second objective of this invention is to provide a method for preparing a lithium-rich manganese-based cathode material, the method specifically comprising the following steps: S1. Nickel manganese hydroxide and lithium salt are mixed in a molar ratio and ground to obtain a mixed powder; the mixed powder is calcined once and then cooled, and then crushed to obtain a matrix powder; S2. After mixing cobalt oxide powder and cerium oxide powder, a coated mixed powder is obtained. The coated mixed powder is then mixed with the matrix powder obtained in step S1 and ground evenly to obtain a mixed powder. S3. The mixed powder obtained in step S2 is subjected to a second calcination treatment and then cooled. After crushing, lithium-rich manganese-based cathode material is obtained.

[0016] Compared with existing technologies, the modified lithium-rich manganese-based cathode material provided by this invention uses a compound of the aforementioned specific general formula as a matrix, and obtains a chemically stable composite coating layer through nano-cobalt oxide and nano-cerium oxide composite coating. Due to the synergistic effect of cobalt and cerium oxide, the specific surface area of ​​the lithium-rich manganese-based material is reduced, and the bonding force with the material surface is increased, avoiding the problem of coating layer detachment and failure. Moreover, the stable coating layer avoids direct contact between the material and the electrolyte, thus significantly improving the problem of poor cycle stability caused by electrolyte decomposition. Furthermore, due to the synergistic effect of cobalt and cerium oxide, the coating layer has extremely low lithium-ion transport resistance, which is more conducive to the utilization of the material's capacity.

[0017] In one possible implementation, in step S1, the nickel manganese hydroxide and lithium salt are in a molar ratio of 1:(1.06-1.2); and in the nickel manganese hydroxide, the molar ratio of Ni:Mn is 3:7.

[0018] Compared to existing technologies, this invention employs the aforementioned molar ratio, meaning that lithium is in excess relative to the transition metals (nickel, cobalt, manganese). This excess lithium compensates for losses due to lithium volatilization or other reactions during calcination, ensuring sufficient lithium content in the final product to form the desired Li-rich layered structure. Appropriate excess lithium also helps improve the electrochemical performance of the material, such as increasing initial charge-discharge efficiency and cycle stability. This is because excess lithium increases oxygen vacancies in the material, thereby promoting lithium-ion transport and reducing impedance at the electrode / electrolyte interface.

[0019] Meanwhile, this invention adjusts the Ni and Mn ratio within the aforementioned range because this value represents a balance between energy density (contributed by nickel) and structural stability (contributed by manganese), ensuring that the material possesses both high capacity and good cycle stability and safety. The lower Ni ratio (30%) and higher Mn content enhance the material's safety and structural stability, as manganese-based materials typically exhibit better thermal stability and overcharge resistance.

[0020] In one possible implementation, in step S1, the mass ratio of the matrix to the lithium salt is 1:(0.2-0.8), and the lithium salt is one of lithium hydroxide, lithium carbonate, lithium nitrate, and lithium oxalate.

[0021] Compared with the prior art, the advantages of the above parameters in this invention are: within this mass ratio range, sufficient lithium can be ensured to form the required lithium-rich layered structure. In particular, when the proportion of lithium salt is close to the upper limit (e.g., 0.8), the loss of lithium volatilization that may occur during calcination can be better compensated, ensuring that there are sufficient lithium ions in the final product to participate in the electrochemical reaction.

[0022] In one possible implementation, the parameters for the first calcination treatment in step S1 are as follows: under an air atmosphere, the temperature is raised to 400-500℃ at a heating rate of 2-10℃ / min and held for 4-6 hours. Then, raise the temperature to 800-1000℃ at a rate of 2-10℃ / min and hold for 12-18 hours.

[0023] Compared with existing technologies, this invention uses the above-mentioned calcination parameters. Through a two-stage heating process, the material can initially form a relatively stable structure at a lower temperature (400-500℃), and further optimize the crystal structure at a higher temperature (800-1000℃). Heating at a slower heating rate of 2-10℃ / min allows for better control of the phase transformation process in the material, giving each element sufficient time to diffuse and rearrange, forming an ideal crystal structure. The longer holding time (especially 12-18 hours at 800-1000℃) provides ample time for the material to complete crystal growth and rearrangement, making the crystal more dense and uniform, which is beneficial to improving the material's electrical and ionic conductivity. Calcination in an air atmosphere can promote the formation of oxides on the material surface, which is very beneficial for the adhesion of subsequent coating layers. In addition, appropriate oxidation conditions also help to activate active sites in the material and improve its electrochemical performance.

[0024] In one possible implementation, the parameters for the secondary calcination treatment in step S3 are as follows: under an air atmosphere, the temperature is raised to 700-800℃ at a heating rate of 5-10℃ / min and held for 5-10 hours.

[0025] Compared with the prior art, the present invention uses the above-mentioned parameters for secondary calcination treatment. The temperature range of 700-800℃ helps to further optimize the interface structure between the matrix and the coating layer, making the crystals in the material more dense and uniform, thereby improving the conductivity and ionic conductivity of the material. The slower heating rate of 5-10℃ / min can effectively reduce the thermal stress caused by rapid heating, avoid the generation of cracks or other defects inside the material, maintain the integrity and consistency of the material, and provide sufficient time for the material to complete crystal growth and rearrangement, ensuring the stability and uniformity of the crystal structure.

[0026] More preferably, in step S3, the parameters for the secondary calcination treatment are as follows: under an air atmosphere, the temperature is raised to 780°C at a heating rate of 5°C / min and held for 10 hours.

[0027] 780℃ is a carefully selected temperature point that can effectively promote uniform crystallization inside the material, making the interface between the matrix and the coating layer more compact and smooth, thereby improving the overall conductivity and ion conductivity of the material. Through the above-mentioned carefully designed secondary calcination process, the initial coulombic efficiency of the material can be effectively improved, and the irreversible capacity loss during the first charge and discharge can be reduced. Attached Figure Description

[0028] Figure 1 The image shows the SEM image of the cathode material prepared in Comparative Example 2. Figure 2 Here is a SEM image of the cathode material prepared in Example 1; Figure 3 This is an EDS image of the positive electrode material prepared in Example 1 of the present invention; Figure 4 The XRD patterns are of the cathode materials prepared in Example 1 and Comparative Examples 1-3. Figure 5 This is a TEM image of the coating layer of the positive electrode material prepared in Example 1; Figure 6 This is a TEM image of the coating layer of the positive electrode material prepared in Example 9. Detailed Implementation

[0029] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.

[0030] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0031] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In some instances, terms having a conventional meaning are defined herein for clarification or ease of reference, and such definitions should not be construed as indicating a significant difference from conventional understanding in the art. The technical methods described or referenced herein are generally well understood by those skilled in the art and employed by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments shall be performed according to the manufacturer's instructions and parameters.

[0032] The technical effects of the present invention will be described below with reference to specific embodiments.

[0033] Example 1: This embodiment provides a lithium-rich manganese-based cathode material, which is prepared by the following method: S1. According to the stoichiometric ratio of Li / (Ni+Mn) = 1.17 / 0.83, mix Li2CO3 and Ni... 0.30 Mn 0.70 (OH)2 is thoroughly mixed and ground to obtain mixed powder a; mixed powder a is heated to 400℃ at a heating rate of 5℃ / min and held for 5h in air atmosphere, and then heated to 800℃ at a heating rate of 2℃ / min and held for 12h. After cooling in the furnace, a solid block material is obtained, which is crushed to obtain lithium-rich manganese-based cathode powder. S2. Mix the mixed powder b formed by cobalt oxide and cerium oxide with the lithium-rich manganese-based cathode powder and grind them evenly to obtain mixed powder c; wherein, the mixing ratio of mixed powder b to lithium-rich manganese-based cathode powder is 1:200, and the mass ratio of cobalt oxide to cerium oxide is 1:5. S3. The mixed powder c is heated to 780°C in air at a heating rate of 5°C / min and held for 10 hours. It is then cooled in the furnace to obtain a solid block material, which is crushed to obtain a coated and modified lithium-rich manganese-based cathode material. Example 2 This embodiment provides a lithium-rich manganese-based cathode material. The only difference from Embodiment 1 is that the mixing ratio of the cobalt oxide and cerium oxide mixture with the cathode material in this embodiment is 1:100. Everything else is the same as in Embodiment 1, and will not be repeated here.

[0034] Example 3 This embodiment provides a lithium-rich manganese-based cathode material. The only difference from Embodiment 1 is that the mixing ratio of the cobalt oxide and cerium oxide mixture with the cathode material in this embodiment is 1:500. Everything else is the same as in Embodiment 1, and will not be repeated here.

[0035] Example 4 This embodiment provides a lithium-rich manganese-based cathode material. The only difference from Embodiment 1 is that the mixing ratio of the cobalt oxide and cerium oxide mixture with the cathode material in this embodiment is 1:1000. Everything else is the same as in Embodiment 1, and will not be repeated here.

[0036] Example 5 This embodiment provides a lithium-rich manganese-based cathode material. The only difference from Embodiment 1 is that the ratio of cobalt oxide to cerium oxide in this embodiment is 1:4. Everything else is the same as in Embodiment 1, and will not be repeated here.

[0037] Example 6 This embodiment provides a lithium-rich manganese-based cathode material. The only difference from Embodiment 1 is that the ratio of cobalt oxide to cerium oxide in this embodiment is 1:3. Everything else is the same as in Embodiment 1, and will not be repeated here.

[0038] Example 7 This embodiment provides a lithium-rich manganese-based cathode material. The only difference from Embodiment 1 is that the ratio of cobalt oxide to cerium oxide in this embodiment is 1:1. Everything else is the same as in Embodiment 1, and will not be repeated here.

[0039] Example 8 This embodiment provides a lithium-rich manganese-based cathode material. The only difference from Embodiment 1 is that in this embodiment, step S3 involves heating the mixed powder c to 800°C in air at a heating rate of 5°C / min and holding it at that temperature for 5 hours. The rest is the same as in Embodiment 1 and will not be repeated here.

[0040] Example 9 This embodiment provides a lithium-rich manganese-based cathode material. The only difference from Embodiment 1 is that in this embodiment, step S3 involves heating the mixed powder c to 700°C in air at a heating rate of 10°C / min and holding it at that temperature for 8 hours. The rest is the same as in Embodiment 1 and will not be repeated here.

[0041] Example 10 This embodiment provides a lithium-rich manganese-based cathode material. The only difference from Embodiment 1 is that in this embodiment, step S3 involves heating the mixed powder c to 750°C in air at a heating rate of 7°C / min and holding it at that temperature for 10 hours. The rest is the same as in Embodiment 1 and will not be repeated here.

[0042] Comparative Example 1 This comparative example provides a lithium-rich manganese-based cathode material, prepared by the following method: Li₂CO₃ and Ni₂ are mixed according to a stoichiometric ratio of Li / (Ni+Mn) = 1.17 / 0.83. 0.30 Mn 0.70 (OH)2 is thoroughly mixed and ground to obtain mixed powder a; mixed powder a is heated to 400℃ at a heating rate of 5℃ / min and held for 5h in air atmosphere, and then heated to 800℃ at a heating rate of 2℃ / min and held for 12h. After cooling in the furnace, a solid block material is obtained, which is crushed to obtain lithium-rich manganese-based cathode powder.

[0043] Comparative Example 2 This comparative example provides a lithium-rich manganese-based cathode material. The only difference from Example 1 is that the "mixed powder b formed by cobalt oxide and cerium oxide" in Example 1 is replaced with the same mass of cerium oxide. Everything else is the same as in Example 1, and will not be repeated here.

[0044] Comparative Example 3 This comparative example provides a lithium-rich manganese-based cathode material. The only difference from Example 1 is that the "mixed powder b formed by cobalt oxide and cerium oxide" in Example 1 is replaced with the same mass of cobalt oxide. Everything else is the same as in Example 1, and will not be repeated here.

[0045] The inventors conducted performance tests on the cathode materials prepared in Examples 1-10 and Comparative Examples 1-3. The test results are shown in Table 1. Table 1: Performance test results of the cathode materials prepared in Examples 1-10 and Comparative Examples 1-3 The comparison between Example 1 and Examples 2-7 shows that the materials prepared under different mixing ratios can improve cycle and rate performance, reduce the specific surface area of ​​the materials, and the co-coated materials have better performance than the single-coated samples. However, the lithium-ion diffusion coefficient decreases and the capacity decreases as the shell thickness increases.

[0046] A comparison of Examples 1 and Examples 8-10 shows that different temperatures and holding times can improve the performance of the bare sample to a certain extent, but the improvement effect is worse than that of Example 1, and the specific surface area is also higher. The reasons for this are as follows: excessively high temperatures may cause the material to undergo excessive crystallization or phase transformation, or even decomposition, thereby destroying the required layered structure and reducing the electrochemical activity of the material. Excessively long holding times may also cause excessive crystallization or phase transformation, or even decomposition, thereby destroying the required layered structure and reducing the electrochemical activity of the material.

[0047] The comparison between Example 1 and Comparative Examples 1-3 shows that the sample without any coating has a high specific surface area and poor battery performance. The sample coated with cobalt oxide alone has a slightly improved battery performance and a slightly reduced specific surface area, but the overall improvement is not significant. The sample coated with cerium oxide alone has a slightly improved battery performance compared to the uncoated sample, but the effect is very poor compared to the samples with both coatings. However, the sample coated with cerium oxide reduces the specific surface area of ​​the material.

[0048] Furthermore, the inventors also observed the cathode materials prepared in Example 1 and Comparative Example 2. Figure 1 The image shown is a SEM image of the cathode material prepared in Comparative Example 2. Figure 2 The image shown is a SEM image of the cathode material prepared in Example 1. Figure 1 and Figure 2 The comparison shows that the surface of the sample coated with cerium oxide alone is not uniform enough, while the surface of the sample coated with both is uniform and the coating effect is good.

[0049] Figure 3Table 2 shows the EDS diagram of the cathode material prepared in Example 1 of this invention. Figure 3 Elemental content analysis table prepared: Table 2: Elemental content analysis of the cathode material prepared in Example 1 from Figure 3 As can be seen from Table 2, the content of cobalt and cerium can be detected at all selected special points, and the locations of the two are consistent, indicating that cobalt and cerium exist uniformly on the surface.

[0050] Figure 4 The XRD patterns of the cathode materials prepared in Example 1 and Comparative Examples 1-3 are shown. Analysis shows that the peak around 28° is the peak produced by cerium oxide coating. However, when cerium oxide is coated alone, the coating layer is easy to fall off, so the peak is not observed. The peak around 54° is the peak produced by cobalt oxide coating. The sample after co-coating contains the peaks of both. Otherwise, even if the peak of cerium oxide appears, it will not have a very obvious peak intensity. Therefore, combined with SEM and XRD analysis, the co-coating in the form of cerium-based cobalt oxide ensures the coating of cerium oxide, and also has the effect of cobalt oxide coating on improving the material.

[0051] Figure 5 This is a TEM image of the coating layer of the positive electrode material prepared in Example 1; Figure 6 This is a TEM image of the coating layer of the cathode material prepared in Example 9. In comparison, the surface of the coating layer of the cathode material prepared in Example 9 is non-uniform, which can be considered as a change in its structure.

[0052] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A lithium-rich manganese-based cathode material, characterized in that, The lithium-rich manganese-based cathode material includes a matrix and a coating layer on the surface of the matrix. In the powder X-ray diffraction pattern of the lithium-rich manganese-based cathode material, there is a peak of cerium oxide at a diffraction angle of (28±0.2)° and a peak of cobalt oxide at a diffraction angle of (54±0.2)°.

2. The lithium-rich manganese-based cathode material as described in claim 1, characterized in that, The coating layer accounts for 0.1-1% of the mass of the lithium-rich manganese-based cathode material, and the molar ratio of cobalt to cerium in the coating layer is 1:(1-5).

3. The lithium-rich manganese-based cathode material as described in claim 1, characterized in that, The molecular formula of the matrix is: Li 1+ a Ni x Mn y O2, where 0.1≤a≤0.5, 0≤x≤0.3, 0≤z≤0.9, and a+x+y=1.

4. The lithium-rich manganese-based cathode material as described in claim 1, characterized in that, The specific surface area of ​​the lithium-rich manganese-based cathode material is 0.73-0.88 cm². 2 / g.

5. A method for preparing a lithium-rich manganese-based cathode material as described in any one of claims 1-4, characterized in that, The preparation method specifically includes the following steps: S1. Nickel manganese hydroxide and lithium salt are mixed in a molar ratio and ground to obtain a mixed powder; the mixed powder is calcined once and then cooled, and then crushed to obtain a matrix powder; S2. After mixing cobalt oxide powder and cerium oxide powder, a coated mixed powder is obtained. The coated mixed powder is then mixed with the matrix powder obtained in step S1 and ground evenly to obtain a mixed powder. S3. The mixed powder obtained in step S2 is subjected to a second calcination treatment and then cooled. After crushing, lithium-rich manganese-based cathode material is obtained.

6. The preparation method according to claim 5, characterized in that, In step S1, the nickel manganese hydroxide and lithium salt are in a molar ratio of 1:(1.06-1.2); and in the nickel manganese hydroxide, the molar ratio of Ni:Mn is 3:

7.

7. The preparation method according to claim 5, characterized in that, In step S1, the mass ratio of the matrix to the lithium salt is 1:(0.2-0.8), and the lithium salt is one of lithium hydroxide, lithium carbonate, lithium nitrate, and lithium oxalate.

8. The preparation method according to claim 5, characterized in that, In step S1, the parameters for the first calcination treatment are as follows: under an air atmosphere, the temperature is raised to 400-500℃ at a heating rate of 2-10℃ / min and held for 4-6 hours. Then, raise the temperature to 800-1000℃ at a rate of 2-10℃ / min and hold for 12-18 hours.

9. The preparation method according to claim 5, characterized in that, In step S3, the parameters for the secondary calcination treatment are as follows: under an air atmosphere, the temperature is raised to 700-800℃ at a heating rate of 5-10℃ / min and held for 5-10 hours.

10. The preparation method according to claim 5, characterized in that, In step S3, the parameters for the secondary calcination treatment are as follows: under air atmosphere, the temperature is raised to 780℃ at a heating rate of 5℃ / min and held for 10 hours.

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