阅读说明：本技术 一种实现精确配锂的富锂锰基正极材料及其制备方法和应用 (Lithium-rich manganese-based positive electrode material for realizing accurate lithium preparation and preparation method and application thereof ) 是由 李宁 赵佳雨 苏岳锋 陈来 董锦洋 卢赟 曹端云 黄擎 吴锋 于 2021-07-29 设计创作，主要内容包括：本发明公开了一种实现精确配锂的富锂锰基正极材料及其制备方法和应用,包括以下步骤：S1、按比例称取对应的可溶性金属盐并混合成金属盐溶液；S2、将金属盐溶液、沉淀剂溶液和络合剂加入反应釜中反应过滤得到前驱体；S3、将前驱体放入马弗炉中,在空气的氛围下煅烧；S4、将前驱体与锂源混合并搅拌,得到混合物；S5、将混合物于马弗炉中烧结即得。本发明通过对富锂锰基正极材料的前驱体在空气中进行氧化预烧,使得前驱体硬度增大,从而更有利于结构的保持,成分结构单一,不仅实现了精确配锂,减少了表面残余锂,增强了结构的稳定性,而且相比于传统方法,该方式高效、经济、操作简单,过程易控制,能够很好地解决传统方法中配锂量偏差的问题。(The invention discloses a lithium-rich manganese-based positive electrode material for realizing accurate lithium preparation, and a preparation method and application thereof, wherein the preparation method comprises the following steps: s1, weighing corresponding soluble metal salts in proportion and mixing the soluble metal salts into a metal salt solution; s2, adding a metal salt solution, a precipitator solution and a complexing agent into a reaction kettle, and reacting and filtering to obtain a precursor; s3, putting the precursor into a muffle furnace, and calcining in the atmosphere of air; s4, mixing the precursor with a lithium source and stirring to obtain a mixture; and S5, sintering the mixture in a muffle furnace to obtain the material. According to the invention, the precursor of the lithium-rich manganese-based anode material is oxidized and presintered in the air, so that the hardness of the precursor is increased, the structure is more favorably maintained, the component structure is single, not only is accurate lithium preparation realized, the residual lithium on the surface is reduced, and the stability of the structure is enhanced, but also compared with the traditional method, the method is efficient, economic and simple to operate, the process is easy to control, and the problem of lithium preparation amount deviation in the traditional method can be well solved.)

1. A method for realizing accurate lithium preparation of a lithium-rich manganese-based positive electrode material is characterized by comprising the following steps of:

s1, weighing and mixing corresponding soluble metal salts according to the proportion of the constituent elements of the lithium-rich manganese-based positive electrode material, and then adding distilled water to prepare a metal salt solution with a certain molar concentration;

s2, weighing a precipitator with a proportional amount to prepare a precipitator solution, using ammonia water as a complexing agent, slowly adding a metal salt solution, the precipitator solution and the complexing agent into a reaction kettle to react for a certain time, filtering to obtain a precipitate, and drying in vacuum to obtain a precursor;

s3, putting the precursor into a muffle furnace, and calcining in the air atmosphere to obtain an oxide precursor;

s4, mixing the oxide precursor and a lithium source in absolute ethyl alcohol according to a certain molar ratio, and stirring until the solvent is completely volatilized to obtain a mixture;

and S5, sintering the mixture in a muffle furnace to finally obtain the lithium-rich manganese-based positive electrode material.

2. The method for realizing accurate lithium matching of the lithium-rich manganese-based positive electrode material as claimed in claim 1, wherein the chemical formula of the lithium-rich manganese-based positive electrode material is xLi₂MnO₃·(1－x)LiMO₂M is one or more of Ni, Co and Mn, and x is more than 0 and less than 1.

3. The method for realizing the precise lithium distribution of the lithium-rich manganese-based cathode material as claimed in claim 1 or 2, wherein in S2, the reaction temperature is controlled to be 50-60 ℃ and the reaction time is controlled to be 10-12 h.

4. The method for realizing the precise lithium distribution of the lithium-rich manganese-based cathode material as claimed in claim 3, wherein the calcination temperature is 500-750 ℃ and the calcination time is 3-6 h in S3.

5. The method for realizing accurate lithium matching of the lithium-rich manganese-based cathode material according to claim 4, wherein the molar ratio of the oxide precursor to the lithium source in S4 is 1: (1.03-1.05).

6. The method for realizing the precise lithium distribution of the lithium-rich manganese-based cathode material as claimed in claim 5, wherein in S5, the temperature rise rate is controlled at 5 ℃/min during sintering, the lithium-rich manganese-based cathode material is sintered at 500 ℃ for 4-6 h first and then at 900 ℃ for 10-13 h.

7. The method for realizing the accurate lithium preparation of the lithium-rich manganese-based cathode material as claimed in claim 1, wherein the precipitant is one or a mixture of sodium hydroxide and sodium carbonate; the lithium salt is one or a mixture of two of lithium hydroxide and lithium carbonate.

8. The method for realizing the accurate lithium matching of the lithium-rich manganese-based positive electrode material as claimed in claim 1, wherein the soluble metal salt corresponding to the constituent element of the lithium-rich manganese-based positive electrode material is sulfate.

9. The lithium-rich manganese-based cathode material for realizing precise lithium preparation is characterized by being prepared by the method for precisely preparing lithium according to any one of claims 1 to 8.

10. The lithium ion battery comprises a lithium ion battery anode, and is characterized in that the lithium ion battery anode comprises an anode material, a binder and a conductive agent, and the anode material is the lithium-rich manganese-based anode material for realizing accurate lithium preparation according to claim 9.

Technical Field

The invention relates to the technical field of lithium ion batteries, in particular to a lithium-rich manganese-based positive electrode material for realizing accurate lithium preparation and a preparation method and application thereof.

Background

With the rapid development of global economy and scientific technology, the demand of people for energy is increasing day by day, and the energy storage crisis of the traditional fossil energy (coal, petroleum and the like) is gradually developed, so that the development and utilization of new energy become a research hotspot. People begin to utilize clean energy such as wind energy and water energy, but the energy has timeliness, and the energy needs to be converted and stored by using a battery and then reasonably utilized. Nickel-metal hydride batteries and lead-acid batteries are secondary batteries that have been used frequently, but have been replaced by lithium ion batteries because of their low energy density and short cycle life.

The requirements of comprehensive cost and performance are met, the positive electrode material is a core part for limiting the development of the lithium ion battery, and the improvement of the performance of the lithium ion battery is very important. The synthesis methods of the cathode material are more, including a coprecipitation method, a solid phase method, a sol-gel method, a spray drying method and the like, each method has respective advantages and disadvantages, and the coprecipitation method is the most widely commercially applied at present from the aspects of energy consumption, efficiency and performance. The precursor material synthesized by the coprecipitation method has uniform particles, accurate element proportion and stable performance, the method utilizes a precipitator to synthesize a transition metal hydroxide or carbonate precursor, and then the transition metal hydroxide or carbonate precursor is mixed with lithium salt to be sintered at high temperature to synthesize the anode material with regular morphology, but the synthesis condition is harsh, long-time high-temperature calcination under oxygen atmosphere is needed, the time and energy consumption are consumed, and the cost is high.

Research shows that before the lithium-mixed calcination, the precursor is pre-oxidized into oxyhydroxide by hydroxide, the crystal form, the particle morphology, the particle size and the distribution of the oxyhydroxide are changed, and the oxyhydroxide has obvious influence on the anode material. The prior literature synthesizes lithium ion battery anode materials by precursors prepared in different pre-oxidation modes, and the results show that: the pre-oxidation mode does not affect the appearance of the precursor or the sample, but has great influence on the crystal phase structure, the average oxidation state of Ni and the electrochemical performance of the sample, and the higher the average oxidation state of Ni in the precursor is, the better the electrochemical performance of the sample is. Particularly for the high-nickel anode material, the problem of cation mixed discharge is obvious due to higher nickel content of the high-nickel anode material, and the lithium storage capacity and the cycle performance of the anode material are seriously reduced, so that the inherent Ni in a system can be reduced by carrying out pre-oxidation treatment on a precursor of the high-nickel anode material²⁺The influence of cation mixing on the cycle performance is relieved. For example, chinese patents CN112186171A (a preoxidation method and application of a lithium nickelate positive electrode material precursor for a lithium ion battery), CN103066257A (a preparation method of a lithium nickel cobalt aluminum oxide for a positive electrode material of a lithium ion battery), CN112490428A (a pretreatment method of a ternary precursor, a product and application thereof), CN108511746A (a preparation method of a preoxidation-modified high-nickel ternary positive electrode material), and the like, these patent technologies use an oxidizing gas or a liquid oxidizing agent to preoxidize the precursor, thereby achieving the purpose of reducing the degree of lithium nickel ion mixing. However, these pre-oxidation treatment methods have the problems of high cost, complicated subsequent treatment and high risk, for example, the use of liquid oxidant still involves the subsequent washing and impurity removal process, which has a great influence on the electrochemical performance of the anode material.

For the lithium-rich manganese-based positive electrode material, the Ni content is relatively low, the cation mixed-discharging degree is relatively low, and the factors which have a large influence on the performance of the positive electrode material are as follows: the two influencing factors easily cause larger error of lithium preparation amount, cannot realize accurate lithium preparation, and finally easily cause poor structural stability and low specific capacity of the lithium-rich manganese-based anode material. Therefore, how to improve the accuracy of the lithium mixing process becomes a problem of extensive research.

Disclosure of Invention

The invention aims to: the inventor finds that although the lithium-rich manganese-based positive electrode material does not have an obvious cation mixed discharge problem, after a precursor of the lithium-rich manganese-based positive electrode material is pre-sintered in air, the hardness of the precursor is increased, primary particles are converted into single-like crystals, high-activity crystal faces of the single-like crystals are exposed more, and the component structure is single, so that the accurate lithium preparation can be realized, and the defects in the prior art are overcome.

The technical scheme adopted by the invention is as follows: a method for realizing accurate lithium preparation of a lithium-rich manganese-based positive electrode material is characterized by comprising the following steps of:

s1, weighing and mixing corresponding soluble metal salts according to the proportion of the constituent elements of the lithium-rich manganese-based positive electrode material, and then adding distilled water to prepare a metal salt solution with a certain molar concentration;

s2, weighing a precipitator with a proportional amount to prepare a precipitator solution, using ammonia water as a complexing agent, slowly adding a metal salt solution, the precipitator solution and the complexing agent into a reaction kettle to react for a certain time, filtering to obtain a precipitate, and drying in vacuum to obtain a precursor;

s3, putting the precursor into a muffle furnace, and calcining in the air atmosphere to obtain an oxide precursor;

s4, mixing the oxide precursor and a lithium source in absolute ethyl alcohol according to a certain molar ratio, and stirring until the solvent is completely volatilized to obtain a mixture;

and S5, sintering the mixture in a muffle furnace to finally obtain the lithium-rich manganese-based positive electrode material.

In the invention, the precursor of the lithium-rich manganese-based anode material is subjected to oxidation pre-sintering in the air, although the problem of obvious cation mixing and discharging does not exist, experiments show that after the precursor is subjected to oxidation pre-sintering, the hardness of the precursor is increased compared with that of the precursor before oxidation pre-sintering, so that the structure is more favorably maintained, particles are prevented from being crushed and agglomeration is reduced, the appearance of the precursor directly influences the appearance of the calcined anode material, the maintenance of an even structure is the key for improving the performance of the anode material, the pre-oxidized precursor can gradually convert the material into a single-like crystal, so that more high-activity crystal faces of the material are exposed, ions are favorably and rapidly diffused, the component structure is single, and accurate lithium preparation can be realized. When the problem of how to accurately prepare lithium is solved, the traditional method is as follows: and excessive lithium source is added to compensate the loss during calcination, which often forms residual alkali on the surface of the material to cause side reaction at the interface of the electrode, and the structural stability is poor. The method not only realizes accurate lithium preparation, reduces residual lithium on the surface and enhances the stability of the structure through a pre-oxidation mode, but also directly carries out pre-oxidation treatment in the air, and compared with the traditional pre-oxidation treatment mode for solving the cation mixed discharge degree, the method has the advantages of high efficiency, economy, simple operation and easily controlled process, and can well solve the problem of lithium preparation amount deviation in the traditional method.

Further, the chemical formula of the lithium-rich manganese-based cathode material is xLi₂MnO₃·(1－x)LiMO₂M is one or more of Ni, Co and Mn, and x is more than 0 and less than 1.

Further, in S2, the reaction temperature is controlled to be 50-60 ℃, and the reaction time is controlled to be 10-12 h.

Further, in S3, the calcination temperature is 500-750 ℃, and the calcination time is 3-6 h.

Further, in S4, the molar ratio of the oxide precursor to the lithium source is 1: (1.03-1.05).

Further, in S5, the temperature rise rate is controlled at 5 ℃/min during sintering, the sintering is firstly carried out for 4-6 h at 500 ℃, and then the sintering is carried out for 10-13 h at 900 ℃.

Further, the precipitator is one or a mixture of two of sodium hydroxide and sodium carbonate; the lithium salt is one or a mixture of two of lithium hydroxide and lithium carbonate.

Further, the soluble metal salt corresponding to the constituent elements of the lithium-rich manganese-based positive electrode material is sulfate.

The invention also discloses a lithium-rich manganese-based anode material for realizing accurate lithium preparation, and the lithium-rich manganese-based anode material is prepared by the method for accurately preparing lithium.

The invention also comprises a lithium ion battery which comprises a lithium ion battery anode, wherein the lithium ion battery anode comprises an anode material, a binder and a conductive agent, and the anode material is the lithium-rich manganese-based anode material for realizing accurate lithium preparation.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. compared with precursors such as carbonate and the like, the oxide precursor after preoxidation has higher hardness, is more favorable for maintaining the structure, preventing particles from being broken, reducing agglomeration and side reaction, and is favorable for circulation stability, and the specific capacity of 179.8mAh/g is still remained after 1C multiplying power circulation for 50 weeks;

2. the preoxidation can gradually convert the material into a quasi-single crystal, so that a high-activity crystal face of the material is more exposed, ions are favorably and rapidly diffused, and the conductivity is improved;

3. the preoxidized precursor has single component, can be accurately matched with lithium, reduces residual lithium on the surface, enhances the stability of the structure, has the first-cycle specific capacity of 257.2mAh/g, and has the first-cycle coulombic efficiency of 81.09 percent;

4. although the lithium-rich manganese-based positive electrode material does not have the obvious problem of cation mixing, the average valence state of transition metal in the precursor can be improved after the precursor is subjected to pre-oxidation treatment, so that the structure is more ordered, and the electrochemical performance is stable.

Drawings

Fig. 1 is an XRD pattern of the oxide precursor prepared in example 1;

fig. 2 is an XRD pattern of the oxide precursor prepared in example 2;

FIG. 3 is an XRD pattern of the oxide precursor prepared in example 3;

FIG. 4 is an XRD pattern of the oxide precursor prepared in example 4;

FIG. 5 is a first cycle charge and discharge curve of a button cell assembled by the lithium-rich manganese-based positive electrode material prepared in example 1;

fig. 6 is a graph of alternating current impedance (EIS) before assembly of the lithium-rich manganese-based positive electrode material prepared in example 2 into a coin cell;

FIG. 7 is a discharge capacity curve of a button cell assembled by the lithium-rich manganese-based cathode material prepared in example 3 and cycled for 50 weeks at a rate of 1C;

FIG. 8 is the first cycle charge and discharge curve of a button cell assembled by the lithium-rich manganese-based positive electrode material prepared in example 4;

FIG. 9 is a thermogravimetric plot of the hydroxide precursors used in examples 1-3;

FIG. 10 is a thermogravimetric plot of the carbonate precursor used in example 4.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Assembling the battery: li prepared in example_1.2Ni_0.2Mn_0.6O₂As an active material, the active material was mixed with acetylene black, PVDF (polyvinylidene fluoride) in a ratio of 8: 1: 1, adding NMP, grinding into slurry, coating the slurry on an aluminum foil by a scraper, drying, and cutting into pieces to prepare a positive plate; then assembling the cell into a CR2025 button type half cell in an argon glove box (water is less than 0.01ppm, oxygen is less than 0.01ppm), wherein the positive electrode is the positive plate, the counter electrode is a lithium plate, the diaphragm is Celgard 2500, and the electrolyte is prepared by mixing the following components in a volume ratio of 1: 1: 1 carbonic acid bis (ester)Methyl ester, diethyl carbonate and ethyl carbonate are used as solvents, and 1mol/L LiPF6 is used as solute to prepare the solution.

Material characterization analysis method:

x-ray diffraction (XRD) test: x-ray diffractometer, instrument model: rigaku Ultima IV-185, Japan;

comprehensive thermal analysis (TG-DSC) test: synchronous thermal analyzer, model: resist 449F 3;

and (3) testing the cycle performance of the battery: the LAND CT 2001A tester was purchased from blue electronics, Inc., Wuhan, Inc.

Example 1

A lithium-rich manganese-based positive electrode material for realizing accurate lithium preparation comprises the following steps:

s1, weighing a molar ratio of 3: 1, mixing manganese sulfate and nickel sulfate, adding distilled water to prepare a metal salt solution (the total molar number of transition metals is 2mol) of 2mol/L, then weighing 4mol of sodium hydroxide to prepare a solution of 4mol/L, and using ammonia water as a complexing agent to control the release of metal ions in the solution;

s2, slowly adding a metal salt solution, a precipitator solution and a complexing agent into a reaction kettle, controlling the reaction temperature to be 50-60 ℃, reacting for 10-12 h, filtering to obtain a precipitate, and vacuum-drying to obtain a hydroxide precursor;

s3, putting the hydroxide precursor into a muffle furnace, and calcining for 5 hours at 500 ℃ to obtain an oxide precursor;

s4, mixing and stirring an oxide precursor and lithium hydroxide (the molar ratio of the precursor to a lithium source is 1: 1.05) by taking absolute ethyl alcohol as a solvent until the solvent is completely volatilized to obtain a mixture;

and S5, transferring the mixture into a crucible, heating to 500 ℃ at a speed of 5 ℃/min in a muffle furnace, preserving heat for 5h, heating to 900 ℃ at the same heating rate, and calcining for 12h to obtain the lithium-rich manganese-based positive electrode material.

The oxide precursor material after the presintering in the embodiment is subjected to a crystal structure test, and is subjected to lithium mixing to synthesize a positive electrode material, so that the electrochemical performance of the positive electrode material is tested, and the specific test results are as follows:

fig. 9 and fig. 10 are thermogravimetric test results of precursors synthesized by a hydroxide coprecipitation method and a carbonate coprecipitation method, respectively, and it is obvious from the test results that a certain amount of crystal water exists in the precursors, which cannot be removed by drying, and in order to realize more accurate lithium preparation, the precursors need to be pre-sintered and calcined into oxides with single components, so that lithium can be prepared more accurately, and the electrochemical performance is better.

FIG. 1 is an X-ray diffraction pattern of a product obtained by pre-burning a hydroxide precursor at 500 ℃ for 5 hours in example 1, and it can be seen from FIG. 1 that the calcined material is mainly composed of Mn₅O₈And NiMnO₃The two phases are composed of single components without impurity phase, and the phase content can be obtained by combining element proportion, so that the lithium can be accurately prepared.

Fig. 5 shows a first cycle charge/discharge curve obtained by assembling the positive electrode material obtained in example 1 into a battery. As can be seen from FIG. 5, the pre-sintered material has a specific discharge capacity of 257.2mAh/g and a first-cycle coulombic efficiency of 81.09%.

Example 2

A lithium-rich manganese-based positive electrode material for realizing accurate lithium preparation comprises the following steps:

s1, weighing a molar ratio of 3: 1, mixing manganese sulfate and nickel sulfate, adding distilled water to prepare a metal salt solution (the total molar number of transition metals is 2mol) of 2mol/L, then weighing 4mol of sodium hydroxide to prepare a solution of 4mol/L, and using ammonia water as a complexing agent to control the release of metal ions in the solution;

s2, slowly adding a metal salt solution, a precipitator solution and a complexing agent into a reaction kettle, controlling the reaction temperature to be 50-60 ℃, reacting for 10-12 h, filtering to obtain a precipitate, and vacuum-drying to obtain a hydroxide precursor;

s3, putting the hydroxide precursor into a muffle furnace, and calcining at 750 ℃ for 3h to obtain an oxide precursor;

s4, mixing and stirring an oxide precursor and lithium hydroxide (the molar ratio of the precursor to a lithium source is 1: 1.03) by taking absolute ethyl alcohol as a solvent until the solvent is completely volatilized to obtain a mixture;

and S5, transferring the mixture into a crucible, heating to 500 ℃ at a speed of 5 ℃/min in a muffle furnace, preserving heat for 5h, heating to 900 ℃ at the same heating rate, and calcining for 12h to obtain the lithium-rich manganese-based positive electrode material.

The oxide precursor material after the presintering in the embodiment is subjected to a crystal structure test, and is subjected to lithium mixing to synthesize a positive electrode material, so that the electrochemical performance of the positive electrode material is tested, and the specific test results are as follows:

FIG. 2 is an X-ray diffraction pattern of a product obtained by pre-burning a hydroxide precursor at 750 ℃ for 3 hours in example 2. As can be seen from FIG. 2, the calcined material consists primarily of Mn₂O₃And NiMnO₃The two-phase composition, although different from the expected single phase, is simpler in composition than that without calcination.

Fig. 6 is an ac impedance diagram of the positive electrode material obtained in example 2, and a semicircle in the high frequency region generally indicates the electrochemical reaction activity and the electron/ion conductivity at the interface. The magnitude of the conductivity is inversely related to the radius of the semicircle, and as can be seen from fig. 6, the material after pre-burning has a smaller semicircle, which indicates that the conductivity is larger, which is beneficial to improving the rate capability of the battery.

Example 3

A lithium-rich manganese-based positive electrode material for realizing accurate lithium preparation comprises the following steps:

s1, weighing a molar ratio of 3: 1, mixing manganese sulfate and nickel sulfate, adding distilled water to prepare a metal salt solution (the total molar number of transition metals is 2mol) of 2mol/L, then weighing 4mol of sodium hydroxide to prepare a solution of 4mol/L, and using ammonia water as a complexing agent to control the release of metal ions in the solution;

s2, slowly adding a metal salt solution, a precipitator solution and a complexing agent into a reaction kettle, controlling the reaction temperature to be 50-60 ℃, reacting for 10-12 h, filtering to obtain a precipitate, and vacuum-drying to obtain a hydroxide precursor;

s3, putting the hydroxide precursor into a muffle furnace, and calcining at 750 ℃ for 5h to obtain an oxide precursor;

s4, mixing and stirring an oxide precursor and lithium hydroxide (the molar ratio of the precursor to a lithium source is 1: 1.03) by taking absolute ethyl alcohol as a solvent until the solvent is completely volatilized to obtain a mixture;

and S5, transferring the mixture into a crucible, heating to 500 ℃ at a speed of 5 ℃/min in a muffle furnace, preserving heat for 5h, heating to 900 ℃ at the same heating rate, and calcining for 12h to obtain the lithium-rich manganese-based positive electrode material.

The oxide precursor material after the presintering in the embodiment is subjected to a crystal structure test, and is subjected to lithium mixing to synthesize a positive electrode material, so that the electrochemical performance of the positive electrode material is tested, and the specific test results are as follows:

FIG. 3 is an X-ray diffraction pattern of a product obtained by pre-burning a hydroxide precursor at 750 ℃ for 5 hours in example 3, and as can be seen from a comparison between FIG. 2 and FIG. 3, oxides obtained by pre-burning at 750 ℃ are Mn regardless of whether the calcination time is 3 hours or 5 hours₂O₃And NiMnO₃Two phases, and excellent electrochemical performance.

It can be seen from the discharge capacity curve of fig. 7 cycling at 1C rate for 50 weeks that the initial specific discharge capacity of the cathode material synthesized after pre-sintering can reach 255.8mAh/g, and the capacity advantage can be maintained continuously even after cycling under a high current condition, and after cycling at 1C rate for 50 weeks, the specific discharge capacity still remains 179.8 mAh/g.

Example 4

A lithium-rich manganese-based positive electrode material for realizing accurate lithium preparation comprises the following steps:

s1, weighing a molar ratio of 3: 1, mixing manganese sulfate and nickel sulfate, adding distilled water to prepare a metal salt solution (the total molar number of transition metals is 2mol) of 2mol/L, then weighing 2mol of anhydrous sodium carbonate to prepare a solution of 2mol/L, and using ammonia water as a complexing agent to control the release of metal ions in the solution;

s2, slowly adding a metal salt solution, a precipitator solution and a complexing agent into a reaction kettle, controlling the reaction temperature to be 50-60 ℃, reacting for 10-12 h, filtering to obtain a precipitate, and vacuum-drying to obtain a hydroxide precursor;

s3, putting the hydroxide precursor into a muffle furnace, and calcining at 750 ℃ for 5h to obtain an oxide precursor;

s4, mixing and stirring an oxide precursor and lithium carbonate (the molar ratio of the precursor to a lithium source is 1: 1.03) by taking absolute ethyl alcohol as a solvent until the solvent is completely volatilized to obtain a mixture;

and S5, transferring the mixture into a crucible, heating to 500 ℃ at a speed of 5 ℃/min in a muffle furnace, preserving heat for 5h, heating to 900 ℃ at the same heating rate, and calcining for 12h to obtain the lithium-rich manganese-based positive electrode material.

The oxide precursor material after the presintering in the embodiment is subjected to a crystal structure test, and is subjected to lithium mixing to synthesize a positive electrode material, so that the electrochemical performance of the positive electrode material is tested, and the specific test results are as follows:

in addition to the burn-in experiment of the hydroxide precursor, the carbonate precursor was also subjected to burn-in. FIG. 4 is an X-ray diffraction pattern of a product obtained by pre-burning a carbonate precursor at 750 ℃ for 5 hours in example 4, and it can be seen from the pattern that oxides after pre-burning are mainly mixed with Mn₃O₄The lattice structures of the silicon nitride and the silicon nitride are relatively consistent. Although a small amount of Ni was present in the precursor, since Ni and Mn were relatively close in size and properties, it was considered that the oxide after the calcination was M₃O₄(M＝Mn，Ni)。

And (4) lithium is distributed through calculation, and the battery is assembled by synthesizing the anode material to carry out charge and discharge tests. Fig. 8 is a first cycle charge and discharge curve diagram of the cathode material synthesized in example 4, and the obtained result is consistent with that of the hydroxide precursor, and the cathode material synthesized by pre-sintering has excellent specific discharge capacity and coulombic efficiency, and the first cycle discharge specific capacity is up to 251.2mAh/g, and coulombic efficiency is 79.85%.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.