A multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material and its preparation method

Abstract

The present invention provides a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material and a preparation method thereof. First, lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, organic fuel, and organic carbon source are dissolved in deionized water to obtain a uniform mixed solution. Then, the mixed solution is atomized to form carbon-containing droplets. Nitrogen is used as a protective gas and a carrier gas to cause the carbon-containing droplets to undergo a self-propagating combustion reaction at a certain ignition temperature to obtain a combustion product powder; the combustion product is placed in a crucible and calcined in an inert atmosphere to obtain a calcined powder; the calcined powder is placed in a crucible and calcined in an air atmosphere to remove carbon; the calcined product is fully ground to obtain a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode powder. The present invention obtains a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material with both micropores and mesopores, which can effectively prolong the cycle stability of the lithium-rich manganese-based positive electrode material. The present invention has a simple process, low energy consumption, low price, high capacity retention rate, and good industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material and a preparation method thereof. Background Art

[0002] Lithium-ion batteries have the advantages of high specific energy, no memory effect and long cycle life, which have injected fresh blood into the development of the new energy field. As the "heart" of electric vehicles, high energy density lithium-ion batteries can effectively overcome the problem of insufficient mileage of electric vehicles. Lithium-rich manganese-based cathode materials have high mass specific capacity under the coupling effect of transition metal cations and oxygen anion redox, becoming a candidate for the next generation of high energy density cathode materials. However, the redox of oxygen anions in lithium-rich manganese-based cathode materials will lead to irreversible lattice oxygen loss (O 2- →O2), which in turn induces irreversible migration and phase transformation of transition metals during the cycle, ultimately leading to problems such as capacity decay, discharge voltage drop, and sluggish electrochemical reaction of lithium-rich manganese-based positive electrode materials.

[0003] Based on this, the applicant started from the perspective of the structure / interface design of lithium-rich manganese-based positive electrode materials, and targeted key scientific issues such as lattice oxygen loss, transition metal migration and irreversible phase change, and electrode / electrolyte interface side reactions of lithium-rich manganese-based positive electrode materials during the cycle process. Through bulk structure design and electrode / electrolyte interface optimization, the applicant regulated the lattice oxygen redox behavior, structural transformation characteristics and electrode / electrolyte interface evolution of lithium-rich manganese-based positive electrode materials during the charge / discharge process, so as to alleviate the problems of capacity decay and voltage drop of lithium-rich manganese-based positive electrode materials during the cycle process.

[0004] The comprehensive performance of lithium-rich manganese-based cathode materials is closely related to their morphology and structure. Compared with the introduction of ion modification and surface coating, morphology control can ensure the purity of the material, while also making the material synthesis simple and convenient. In actual production, to improve the comprehensive performance of lithium-rich manganese-based cathode materials, lithium-rich manganese-based cathode materials are usually synthesized into solid micron-spherical morphologies or nano-sized irregular geometric morphologies. These two types of materials can greatly shorten the diffusion path of ions and electrons, ensuring full contact between the material and the electrolyte interface, thereby achieving the purpose of improving electrochemical performance.

[0005] The droplet combustion method has inherent advantages in the preparation of nano-metal oxide spherical powders and has been widely used. Carbon materials, with their excellent chemical stability, structural strength, and barrier properties, have also been widely used in applications such as grain refinement. By leveraging the synthetic simplicity of droplet combustion and the grain refinement properties of carbon, it is envisioned that the construction of hierarchically porous micro- and nanostructured lithium-rich manganese-based cathode materials could meet the demand for high-performance cathode materials for lithium-ion batteries. Summary of the Invention

[0006] The present invention aims to provide a multi-level porous micro-nanostructured lithium-manganese-based positive electrode material and a preparation method thereof, so as to solve the technical problem that the comprehensive performance of existing lithium-manganese-rich positive electrode materials is not ideal.

[0007] To achieve the above objectives, the present invention provides a method for preparing a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material, the specific steps of which are as follows:

[0008] (1) First, lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, organic fuel, and organic carbon source are dissolved in deionized water to obtain a uniform mixed solution. Then, the mixed solution is atomized to form carbon-containing droplets. Nitrogen is used as a protective gas and a carrier gas to cause the carbon-containing droplets to undergo a self-propagating combustion reaction at a certain ignition temperature to obtain a combustion product powder.

[0009] (2) placing the combustion product obtained in step (1) in a crucible and calcining in an inert atmosphere to obtain a calcined powder;

[0010] (3) placing the calcined powder obtained in step (2) in a crucible and calcining in an air atmosphere to remove carbon;

[0011] (4) fully grinding the calcined product obtained in step (3) to obtain a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode powder;

[0012] The molar ratio of lithium nitrate, manganese nitrate, cobalt nitrate and nickel nitrate is 1.2:0.54:0.13:0.13; the ratio of the total molar amount of lithium nitrate, manganese nitrate, cobalt nitrate and nickel nitrate to the molar amount of organic fuel and organic carbon source is 1:0.5-3:0.5-6.

[0013] Preferably, in step (1), the organic fuel is selected from at least one of urea, glycine, and alanine; and the organic carbon source is selected from at least one of sucrose, glucose, starch, and citric acid.

[0014] Preferably, in step (1), the flow rate of nitrogen is 0.5 to 3 L / min.

[0015] Preferably, in step (1), the ignition temperature of the carbon-containing droplets is 600-1000°C.

[0016] Preferably, in step (2), the inert atmosphere is selected from nitrogen or argon.

[0017] Preferably, in step (2), the calcination process conditions are: calcination at 500-1000° C. for 0.5-5 hours.

[0018] Preferably, in step (3), the calcination process conditions are: calcination at 600-800° C. for 1-6 hours.

[0019] The present invention also provides a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material, which is obtained by the above-mentioned preparation method.

[0020] The principle of the present invention is:

[0021] The present invention adds an organic carbon source (such as glucose) to a mixed solution of an organic fuel (such as urea) and an oxidant (such as a nitrate, such as lithium nitrate). After achieving uniform mixing of the raw materials at the molecular level, the mixture is atomized to form tiny carbon-containing droplets. At a certain temperature, a self-propagating combustion reaction is initiated within the carbon-containing droplets. This reaction results in an exothermic redox reaction between the nitrate and the organic fuel, while the organic carbon source undergoes endothermic decomposition to form carbon particles. The released heat instantly converts the nitrate into the corresponding metal oxide particles. Simultaneously, these metal oxide particles dissolve into a metal composite oxide (i.e., a lithium-rich manganese-based cathode material) and are uniformly "embedded" within a matrix of hollow carbon spheres formed by the pyrolysis and carbonization of glucose. The fine carbon particles effectively disperse and isolate the metal composite oxide particles, facilitating the production of uniform and fine metal composite oxide nanoparticles. Furthermore, the combustion product gases, such as CO2, N2, and H2O, exert an impact force, forming numerous micropores between the metal composite oxide nanoparticles. The carbon-based hollow sphere powder is then calcined in an inert atmosphere to fully dissolve and crystallize the metal composite oxide nanoparticles. The carbon particles continue to disperse and isolate the metal composite oxide nanoparticles, preventing them from sintering and agglomerating. The carbon-based hollow sphere powder is then calcined in air to remove excess carbon particles through carbon combustion, retaining the hollow spheres formed by the solid-solution metal composite oxides. Mesopores are then formed within the hollow spheres, resulting in micron-sized hollow spheres composed of the solid-solution metal composite oxide nanoparticles. This creates a multi-level micro-nanostructured lithium-manganese-rich cathode material with both microporous and mesoporous structures.

[0022] The present invention has the following beneficial effects:

[0023] Various water-soluble raw materials in the initial solution are uniformly mixed at the atomic level. During the combustion reaction, LiMnO2, LiNiO2, LiCoO2 and carbon hollow spheres are all formed in situ, and the three metal composite oxides are uniformly embedded in the carbon hollow sphere matrix. In addition, the impact of the large amount of gas generated causes a large number of micropores to form between the metal composite oxides. The fine carbon particles can also play a good dispersing and isolating role, and uniformly dispersed nanoscale metal oxide particles can be obtained. Subsequently, calcined in an inert atmosphere, these metal oxides are in situ solid-solution converted into lithium-manganese-rich positive electrode powder materials, and the carbon particles continue to prevent the solid-solution metal oxide particles from agglomerating and growing. Finally, after calcination and decarbonization in an air atmosphere, a large number of uniform mesopores can also be formed in the micron-sized hollow spheres. The morphology and uniformity of the above-mentioned micropores, mesopores and micro-nano combined structures can be controlled by adjusting the raw material ratio and combustion parameters. Therefore, this method can solve the problem of precisely controlling and preparing micro-mesoporous structures, resulting in a lithium-rich manganese-based cathode material with a multi-level micro-nanostructure that combines both micropores and mesopores. This method can effectively extend the cycling stability of lithium-rich manganese-based cathode materials. The present invention features a simple process, low energy consumption, low cost, and high capacity retention, and has promising prospects for industrial application.

[0024] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 This is the SEM image of the multi-level porous micro-nanostructure lithium-rich manganese-based positive electrode material.

[0027] Figure 2 This is the XRD of the multi-level porous micro-nanostructure lithium-rich manganese-based positive electrode material.

[0028] Figure 3 This is a rate performance diagram of a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material.

[0029] Figure 4 This is a 1C rate 100 cycle performance diagram of the multi-level porous micro-nanostructure lithium-rich manganese-based positive electrode material. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims.

[0031] Example 1

[0032] The multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material and its preparation method described in this embodiment specifically include the following steps:

[0033] (1) Lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, urea, and glucose were dissolved in deionized water to obtain a mixed solution, wherein the molar ratio of lithium, manganese, cobalt, and nickel in the nitrate was 1.2:0.54:0.13:0.13, the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to glucose was 1:0.5, and the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to urea was 1:2, and the solution was atomized to form carbon-containing droplets, and nitrogen was used as a protective gas to cause the droplets to self-propagate combustion at 700°C;

[0034] (2) The powder obtained in step (1) was calcined at 700°C in a nitrogen atmosphere for 5 h, placed in a crucible, and then calcined at 650°C in an air atmosphere for 4 h;

[0035] (3) The powder obtained in step (2) is fully ground to obtain a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material.

[0036] The SEM of the positive electrode material Figure 1 , XRD see Figure 2 .

[0037] Example 2

[0038] The method for preparing a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material described in this embodiment specifically includes the following steps:

[0039] (1) Lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, urea, and glucose were dissolved in deionized water to obtain a mixed solution, wherein the molar ratio of lithium, manganese, cobalt, and nickel in the nitrate was 1.2:0.54:0.13:0.13, the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to glucose was 1:3, and the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to urea was 1:3. Using nitrogen as a protective gas, carbon-containing droplets were burned at 900°C to obtain a combustion product powder;

[0040] (2) The powder obtained in step (1) was calcined at 900°C in a nitrogen atmosphere for 1 hour, placed in a crucible, and then calcined at 650°C in an air atmosphere for 1 hour;

[0041] (3) The powder obtained in step (2) is fully ground to obtain a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material.

[0042] Example 3

[0043] The method for preparing a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material described in this embodiment specifically includes the following steps:

[0044] (1) Lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, alanine, and starch were dissolved in deionized water to obtain a mixed solution, wherein the molar ratio of lithium, manganese, cobalt, and nickel in the nitrate was 1.2:0.54:0.13:0.13, the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to starch was 1:6, and the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to alanine was 1:3. Nitrogen was used as a protective gas, and carbon-containing droplets were burned at 1000°C to obtain combustion product powder;

[0045] (2) The powder obtained in step (1) was calcined at 700°C in a nitrogen atmosphere for 5 h, placed in a crucible, and then calcined at 650°C in an air atmosphere for 0.5 h;

[0046] (3) The powder obtained in step (2) is fully ground to obtain a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material.

[0047] Example 4

[0048] The method for preparing a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material described in this embodiment specifically includes the following steps:

[0049] (1) Lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, urea, and sucrose are dissolved in deionized water to obtain a mixed solution, wherein the molar ratio of lithium, manganese, cobalt, and nickel in the nitrate is 1.2:0.54:0.13:0.13, the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to sucrose is 1:3, and the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to urea is 1:6. Using nitrogen as a protective gas, carbon-containing droplets are burned at 900°C to obtain combustion product powder;

[0050] (2) The powder obtained in step (1) was calcined at 800°C in a nitrogen atmosphere for 4 h, placed in a crucible, and then calcined at 650°C in an air atmosphere for 4 h;

[0051] (3) The powder obtained in step (2) is fully ground to obtain a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material.

[0052] Example 5

[0053] The method for preparing a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material described in this embodiment specifically includes the following steps:

[0054] (1) Lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, glycine, and glucose were dissolved in deionized water to obtain a mixed solution, wherein the molar ratio of lithium, manganese, cobalt, and nickel in the nitrate was 1.2:0.54:0.13:0.13, the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to glucose was 1:3, and the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to glycine was 1:6. Using nitrogen as a protective gas, carbon-containing droplets were burned at 900°C to obtain combustion product powder;

[0055] (2) The powder obtained in step (1) was calcined at 700°C in a nitrogen atmosphere for 1 h, placed in a crucible, and then calcined at 650°C in an air atmosphere for 6 h;

[0056] (3) The powder obtained in step (2) is fully ground to obtain a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material.

[0057] Comparative Example 1

[0058] A lithium-rich manganese-based positive electrode material and a preparation method thereof, specifically comprising the following steps:

[0059] (1) Lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, urea, and glucose are dissolved in deionized water to obtain a mixed solution, wherein the molar ratio of lithium, manganese, cobalt, and nickel in the nitrate is 1.2:0.5:0.15:0.15, the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to glucose is 1:3, and the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to urea is 1:2, and the solution is atomized to form carbon-containing droplets, and nitrogen is used as a protective gas to cause the droplets to self-propagate combustion at 700°C;

[0060] (2) The powder obtained in step (1) was calcined at 700°C in a nitrogen atmosphere for 5 h, placed in a crucible, and then calcined at 650°C in an air atmosphere for 0.5 h;

[0061] (3) Grind the powder obtained in step (2) to obtain a lithium-rich manganese-based positive electrode material.

[0062] Comparative Example 2

[0063] A lithium-rich manganese-based positive electrode material and a preparation method thereof, specifically comprising the following steps:

[0064] (1) Lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, glycine, and glucose were dissolved in deionized water to obtain a mixed solution, wherein the molar ratio of lithium, manganese, cobalt, and nickel in the nitrate was 1.2:0.54:0.13:0.13, and no organic carbon source was added to the mixed solution. The molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to urea was 1:2, and the solution was atomized to form carbon-containing droplets. Nitrogen was used as a protective gas, and the droplets were subjected to self-propagating combustion at 700°C.

[0065] (2) The powder obtained in step (1) was calcined at 700°C in a nitrogen atmosphere for 5 h, placed in a crucible, and then calcined at 650°C in an air atmosphere for 0.5 h;

[0066] (3) Grind the powder obtained in step (2) to obtain a lithium-rich manganese-based positive electrode material.

[0067] Comparative Example 3

[0068] A lithium-rich manganese-based positive electrode material and a preparation method thereof, specifically comprising the following steps:

[0069] (1) Lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, urea, and glucose were dissolved in deionized water to obtain a mixed solution, wherein the molar ratio of lithium, manganese, cobalt, and nickel in the nitrate was 1.2:0.54:0.13:0.13, the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to glucose was 1:0.5, and the molar ratio of the sum of lithium, manganese, cobalt, and nickel in the nitrate to urea was 1:5, and the solution was atomized to form carbon-containing droplets, and nitrogen was used as a protective gas to cause the droplets to self-propagate combustion at 700°C;

[0070] (2) The powder obtained in step (1) was calcined at 700°C in a nitrogen atmosphere for 5 h, placed in a crucible, and then calcined at 650°C in an air atmosphere for 4 h;

[0071] (3) Grind the powder obtained in step (2) to obtain a lithium-rich manganese-based positive electrode material.

[0072] Performance evaluation

[0073] Related testing: Using PVDF (polyvinylidene fluoride) as a binder and NMP (N-methylpyrrolidone) as a solvent, a hierarchically porous micro-nanostructured lithium-rich manganese-based cathode material, conductive carbon black, and PVDF were ground and mixed at a mass ratio of 8:1:1. The mixture was then poured into 1.5 ml of NMP and stirred for 12 hours to obtain a cathode slurry. The slurry was evenly coated on aluminum foil, dried in a vacuum oven at 100°C for 12 hours, and then cut into 14 mm diameter discs. The prepared discs served as the positive electrode, a lithium metal sheet as the negative electrode, and a polypropylene microporous membrane as the separator. A 1 mol / L LiPF₆ solution dissolved in a 1:1:1 volume ratio of EC (ethylene carbonate), DMC (dimethyl carbonate), and EMC (ethyl methyl carbonate) was used as the electrolyte. CR2025 stainless steel button cells were assembled in an argon-filled glove box with a moisture content below 0.1 ppm. After 4 hours of stagnation, the cells were tested for charge and discharge performance at room temperature.

[0074] The batteries provided in Example 1 and Example 2 prepared under the above conditions were subjected to performance tests. The testing instrument was a Xinwei battery testing system, and the test conditions were as follows: rate performance test and cycle performance test were performed at a voltage of 2.4~5V, wherein the rate performance was tested under 0.2C, 0.5C, 1C, 2C, 5C, 10C and 0.2C test conditions, and the cycle performance was activated at a rate of 0.1C, followed by a charge and discharge test at a rate of 1C to obtain the capacity retention rate after 100 cycles. The test results are shown in Table 1. Figure 3 This is a rate performance diagram of the multi-level porous micro-nanostructure lithium-rich manganese-based positive electrode materials of Examples 1 and 2. Figure 4 This is a 1C rate 100 cycle performance diagram of the multi-level porous micro-nanostructure lithium-rich manganese-based positive electrode materials of Examples 1 and 2.

[0075] Table 1

[0076]

[0077] Depend on Figure 3 、 4 And Table 1 can be obtained:

[0078] (1) The lithium-ion battery assembled with the multi-level porous micro-nanostructure lithium-rich manganese-based positive electrode material provided in Examples 1 to 5 maintains a relatively balanced advantage in terms of first-cycle specific capacity, first-cycle coulombic efficiency and capacity retention rate, and exhibits high cycle stability;

[0079] (2) By comparing Example 1 with Examples 2 and 3, it can be seen that the molar ratio of the sum of lithium, manganese, cobalt and nickel in the nitrate described in step (1) of the present invention to the organic carbon source will affect the performance of the lithium-ion battery; when the molar concentration ratio is 3, the lithium-ion battery has good cycle stability. This is because an appropriate amount of organic carbon source can construct uniform mesopores, and the obtained multi-level porous micro-nanostructure lithium-rich manganese-based positive electrode material can fully contact with the electrolyte, affecting the subsequent electrochemical performance of the lithium battery; if too much organic carbon source is added, although the primary particles can be further refined, the excessively fine primary particles will aggravate the side reactions in the charge and discharge process, which is not conducive to the subsequent cycle stability of the positive electrode material;

[0080] (3) By comparing Example 2 with Example 4, it can be seen that the type of organic carbon source in step (1) of the present invention affects the performance of the lithium-ion battery; when the organic carbon source is glucose, it can be seen from SEM that the primary particles of the prepared lithium-rich manganese-based positive electrode material have obvious boundaries, and the gaps on the spherical particles can be clearly seen, which is beneficial to the improvement of the cycle stability of the lithium-ion battery material;

[0081] (4) By comparing Example 2 with Example 5, it can be seen that the type of organic fuel in step (1) of the present invention will affect the performance of the lithium-ion battery; when the type of organic fuel described in the step is urea, the lithium-ion battery has better cycle stability. This is because the decomposition of urea during the droplet combustion reaction will produce more gas, and the carbon / lithium-rich manganese-based composite oxide spherical particles formed by the gas impact can obtain a multi-level pore micro-nanostructure lithium-rich manganese-based positive electrode material with suitable micropores and mesopores;

[0082] (5) By comparing Example 2 with Comparative Examples 1 to 3, it can be seen that the preparation method of the multi-level porous micro-nano structure lithium-rich manganese-based positive electrode material provided by the present invention can conveniently and quickly construct a multi-level porous micro-nano spherical structure, effectively increasing the contact area between the lithium-rich manganese-based positive electrode material and the electrolyte, and increasing the cycle stability of the lithium-ion battery; the preparation method of the multi-level porous micro-nano structure lithium-rich manganese-based positive electrode material provided by the present invention has a simple process and low requirements on equipment, which is conducive to large-scale promotion and use.

[0083] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material, characterized in that: The specific steps are as follows: (1) First, lithium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, organic fuel, and organic carbon source are dissolved in deionized water to obtain a uniform mixed solution. Then, the mixed solution is atomized to form carbon-containing droplets. Nitrogen is used as a protective gas and a carrier gas to cause the carbon-containing droplets to undergo a self-propagating combustion reaction at a certain ignition temperature to obtain a combustion product powder. (2) placing the combustion product obtained in step (1) in a crucible and calcining in an inert atmosphere to obtain a calcined powder; (3) placing the calcined powder obtained in step (2) in a crucible and calcining in an air atmosphere to remove carbon; (4) fully grinding the calcined product obtained in step (3) to obtain a multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode powder; The molar ratio of lithium nitrate, manganese nitrate, cobalt nitrate and nickel nitrate is 1.2:0.54:0.13:0.13; the ratio of the total molar amount of lithium nitrate, manganese nitrate, cobalt nitrate and nickel nitrate to the molar amount of organic fuel and organic carbon source is 1:0.5-3:0.5-6.

2. The preparation method according to claim 1, characterized in that In step (1), the organic fuel is selected from at least one of urea, glycine, and alanine; and the organic carbon source is selected from at least one of sucrose, glucose, starch, and citric acid.

3. The preparation method according to claim 1, characterized in that In step (1), the flow rate of nitrogen is 0.5 to 3 L / min.

4. The preparation method according to claim 1, characterized in that In step (1), the ignition temperature of the carbon-containing droplets is 600-1000°C.

5. The preparation method according to claim 1, characterized in that In step (2), the inert atmosphere is selected from nitrogen or argon.

6. The preparation method according to claim 1, characterized in that In step (2), the calcination process conditions are: calcination at 500-1000° C. for 0.5-5 hours.

7. The preparation method according to claim 1, characterized in that In step (3), the calcination process conditions are: calcination at 600-800°C for 1-6 hours.

8. A multi-level porous micro-nanostructured lithium-rich manganese-based positive electrode material, characterized in that: The invention is obtained by the preparation method according to any one of claims 1 to 7.

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