Manganese-rich precursor, preparation method thereof, positive electrode material and lithium-ion battery

Abstract

The present invention provides a manganese-rich precursor and a preparation method thereof, a positive electrode material, and a lithium-ion battery, and relates to the technical field of lithium-ion battery materials. Pure water, a dispersant, and a complexing agent are added to a container passed through an inert atmosphere to prepare a base liquid, wherein the dispersant concentration in the base liquid is controlled to be 1-10 g / L, the complexing agent concentration is controlled to be 0.10-0.40 mol / L, and a precipitant is added to adjust the pH value of the base liquid to 9.5-10.5; a mixed salt solution, a precipitant, and a complexing agent are added to the container to carry out a coprecipitation reaction, and the reaction is stopped when the particle size D50 of the precipitated product is 5-12 μm; the precipitated product is centrifuged, washed, and dried. The manganese-rich precursor prepared by the method of the present invention has the characteristics of large pores, thin primary flaky particles, and good secondary particle sphericity.

Description

Technical Field

[0001] The present invention relates to the field of lithium-ion battery materials, and in particular to a manganese-rich precursor and a preparation method thereof, a positive electrode material and a lithium-ion battery. Background Art

[0002] With the continuous development of environmental problems and energy demand, lithium-ion batteries as energy storage tools have also received more and more attention. The future development trend of lithium-ion batteries is higher energy density and lower price. At present, traditional commercial cathode materials, such as lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, ternary, etc., are limited in improving the energy density of their batteries due to their low theoretical specific capacity. Due to the abundant reserves and low price of manganese, lithium-rich manganese-based cathode materials that mainly use manganese as raw material have received widespread attention. Lithium-rich manganese-based materials have the advantages of high energy density, high voltage platform, low cobalt content, and environmental friendliness. They are considered to be one of the key cathode materials for realizing the next generation of high-energy-density lithium-ion batteries.

[0003] At present, lithium-rich manganese-based material precursors are usually prepared by two co-precipitation methods: carbonate and hydroxide. When the carbonate process is used, the precursor easily forms dense secondary spheres, but the transition metal precipitation is usually incomplete, resulting in component deviation and cost waste. When the hydroxide process is used, the precursor's primary flaky particles are usually thicker and larger, with small porosity and poor secondary sphericity. On the one hand, this precursor morphology does not have sufficient contact with the lithium source during the sintering process, requiring a higher sintering temperature. On the other hand, the sintered finished product has larger primary particles. After being assembled into a battery, the lithium ion transfer impedance of the positive electrode is large, and the material capacity and rate performance are low. Therefore, the synthesis of porous hydroxide precursors is beneficial to the full contact with the lithium source and the uniform diffusion of lithium ions during the sintering process. On the other hand, the finished product inherits the porous characteristics of the precursor, increases the contact area between the material and the electrolyte, shortens the migration path of lithium ions, and provides more channels for the transmission of lithium ions, thereby improving the electrochemical performance of the material. For example, patents CN114804228A and CN115124089A use oxygen or oxidant H2O2 to refine the primary particles during the precursor synthesis process to form a porous structure of the precursor, increase the contact area with the lithium source reaction, and thus improve the capacity and rate performance of the material. However, this method of introducing oxidants is easy to cause the Mn 2+ Oxidation occurs, which is not conducive to the uniform precipitation of the precursor components. Patents CN116924487A and CN114665086A respectively use carbonate and magnesium acetate as pore-forming agents to form a porous structure, but require additional processes to remove the pore-forming agents, which is relatively complex and costly.

[0004] Therefore, a simple and reliable method for synthesizing spherical hydroxide precursors with thin primary particles and high porosity is needed to improve the electrochemical performance of lithium-rich manganese-based cathode materials, such as capacity, rate, and cycle performance. Summary of the Invention

[0005] One of the objectives of the present invention is to provide a manganese-rich precursor. By adding a specific dispersant and controlling the process, a manganese-rich precursor with large pores, thin primary particles, and good secondary particle sphericity is synthesized. This is beneficial to the rapid diffusion of lithium ions and sintering uniformity during the sintering process, significantly improving the capacity, rate and cycle performance of the manganese-rich material.

[0006] A second object of the present invention is to provide a method for preparing the manganese-rich precursor.

[0007] A third object of the present invention is to provide a positive electrode material prepared from the manganese-rich precursor.

[0008] A fourth object of the present invention is to provide a lithium-ion battery comprising the positive electrode material.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0010] In the first aspect, the present invention provides a manganese-rich precursor, the chemical formula of the manganese-rich precursor is: Mn x Ni y Co 1-x-y (OH)2, where 0.5≤x≤0.9, 0.1≤y≤0.4;

[0011] The manganese-rich precursor is a spherical or quasi-spherical secondary particle with a macroporous structure formed by agglomeration of flaky primary particles;

[0012] Wherein, the manganese-rich precursor has the following characteristics:

[0013] (1) The pore size of the secondary particles is 100nm-1μm;

[0014] (2) The thickness of the flaky primary particles is 10-60 nm;

[0015] (3) The BET of the manganese-rich precursor is 20-60m 2 / g.

[0016] In a second aspect, the present invention provides a method for preparing a manganese-rich precursor, comprising the following steps:

[0017] In a container filled with an inert atmosphere, pure water, a dispersant, and a complexing agent are added to prepare a base liquid, wherein the concentration of the dispersant in the base liquid is controlled to be 1-10 g / L, the concentration of ammonia is controlled to be 0.1-0.4 mol / L, and a precipitant is added to adjust the pH value of the base liquid to 9.5-10.5; wherein the dispersant is one or more polyethylene glycols having a relative molecular weight between 400 and 2000;

[0018] A metal salt solution, a precipitant and a complexing agent are simultaneously added to a bottom liquid for reaction, and the pH value is controlled to remain unchanged during the reaction process. The reaction is stopped when the particle size D50 of the precipitated slurry grows to 5-12 μm. The precipitated slurry is centrifuged, washed and dried to obtain a manganese-rich precursor.

[0019] Specifically, a method for preparing a manganese-rich precursor includes the following steps:

[0020] (1) preparing a metal salt solution, a precipitant, and a complexing agent: the total concentration of metal ions in the metal salt solution is 1-4 mol / L, the concentration of the precipitant is 2-8 mol / L, and the concentration of the complexing agent is 1-8 mol / L;

[0021] (2) adding pure water, a dispersant, and a complexing agent into a container filled with an inert atmosphere to prepare a base solution, controlling the concentration of the dispersant in the base solution to be 1-10 g / L and the concentration of ammonia to be 0.1-0.4 mol / L, and adding a precipitant to adjust the pH value of the base solution to 9.5-10.5; wherein the dispersant is one or more polyethylene glycols having a relative molecular weight between 400 and 2000;

[0022] (3) adding a metal salt solution, a precipitant, and a complexing agent to the bottom liquid simultaneously for reaction, controlling the pH to remain constant during the reaction, and stopping the reaction until the particle size D50 of the precipitated slurry grows to 5-12 μm; and discharging the slurry after aging;

[0023] (4) Post-treatment: centrifuging, washing, and drying the slurry to obtain a manganese-rich precursor.

[0024] In some embodiments, in step (1), the metal salt comprises a manganese salt, a nickel salt, and optionally a cobalt salt; the manganese salt is one or more selected from manganese sulfate, manganese chloride, manganese nitrate, and manganese acetate; the nickel salt is one or more selected from nickel sulfate, nickel nitrate, nickel acetate, and nickel chloride; the cobalt salt is one or more selected from cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt acetate; the molar ratio of Mn, Ni, and Co is x:y:1-xy, wherein 0.5≤x≤0.9, 0.1≤y≤0.4;

[0025] The precipitant is one or more selected from sodium hydroxide aqueous solution, potassium hydroxide aqueous solution and lithium hydroxide aqueous solution;

[0026] The complexing agent is one or more selected from ammonia water, ammonium bicarbonate aqueous solution and ammonium carbonate aqueous solution.

[0027] In some embodiments, in step (3), the reaction conditions include: reaction temperature of 40-60° C., stirring speed of 500-1000 rpm, reaction time of 10-30 h; and controlling the ammonia content in the reaction system to be 0.1-0.4 mol / L.

[0028] In some embodiments, in step (3), the aging temperature is 20-60° C., and the aging time is 1-12 h.

[0029] In some embodiments, in step (4), the drying conditions include: a drying temperature of 80-120° C. and a drying time of 8-24 h.

[0030] The chemical formula of the manganese-rich precursor obtained by the method of the second aspect is: Mn x Ni y Co 1-x-y (OH)2, wherein 0.5≤x≤0.9, 0.1≤y≤0.4; the manganese-rich precursor is a spherical or quasi-spherical secondary particle with a macroporous structure formed by agglomerating thin-flaked primary particles; wherein the manganese-rich precursor has the following characteristics: (1) the pore size of the secondary particle is 100nm-1μm; (2) the thickness of the thin-flaked primary particles is 10-60nm; (3) the BET of the manganese-rich precursor is 20-60m 2 / g.

[0031] The above preparation method produces a macroporous manganese-rich precursor with thin primary flaky particles by introducing a specific dispersant and controlling the coprecipitation process conditions. The addition of polyethylene glycol, a highly soluble oligomeric macromolecular polymer with a relative molecular weight between 400 and 2000, utilizes its dispersing properties to inhibit disordered aggregation during the preparation of the manganese-rich precursor, improving its sphericity and dispersibility. Furthermore, its long-chain structure induces the formation of pores within the secondary spheres of the manganese-rich precursor. A low pH value is also employed to promote the radial growth rate of the primary flaky particles, resulting in a thin primary particle morphology that facilitates the accumulation of macroporous structures.

[0032] In a third aspect, the present invention further provides a positive electrode material obtained by sintering the above-mentioned manganese-rich precursor.

[0033] In a fourth aspect, the present invention further provides a lithium-ion battery comprising the above-mentioned positive electrode material.

[0034] Beneficial effects

[0035] (1) The manganese-rich precursor prepared by the method of the present invention has the characteristics of large pores, thin primary flaky particles, and good secondary particle sphericity, which lays a good foundation for the subsequent preparation of lithium-rich manganese-based positive electrode materials. The lithium-rich manganese-based positive electrode material obtained from the macroporous manganese-rich precursor provided by the present invention has good rate performance and can significantly improve the volume energy density of the battery when applied to the battery, and has broad market prospects.

[0036] (2) The preparation method of the present invention is simple, has strong applicability, requires relatively simple equipment, is easy to operate, has low control difficulty, has high efficiency in industrial manufacturing, is low in cost, and is easy to scale up, promote, and apply.

[0037] The present invention has been described in detail above, but the above embodiments are merely illustrative in nature and are not intended to limit the present invention. In addition, the present invention is not limited by any theory described in the above prior art or invention summary or the following examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 shows a 2500x electron microscope image of the manganese-rich precursor prepared in Example 1;

[0039] Figure 2 shows a 10,000x electron microscope image of the manganese-rich precursor prepared in Example 1;

[0040] Figure 3 The 2500x electron microscope image of the manganese-rich precursor prepared in Comparative Example 1 is shown;

[0041] Figure 4 The 10,000-fold electron microscope image of the manganese-rich precursor prepared in Comparative Example 1 is shown. DETAILED DESCRIPTION

[0042] The present invention will be further described below with reference to the examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed in the present invention.

[0043] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, and methods in the art.

[0044] Example 1

[0045] A method for preparing a manganese-rich precursor comprises the following steps:

[0046] (1) nickel sulfate, manganese sulfate, and cobalt sulfate were weighed and dissolved in deionized water at a molar ratio of Ni:Mn:Co of 0.30:0.6:0.1 to prepare a mixed salt solution with a total concentration of 2 mol / L;

[0047] Weigh NaOH and dissolve it in deionized water to prepare a 4 mol / L solution as a precipitant;

[0048] Weigh ammonia water and dissolve it in deionized water to prepare a solution with a concentration of 1 mol / L as a complexing agent;

[0049] (2) Adding pure water to a reactor filled with an inert atmosphere, adding ammonia water and polyethylene glycol PEG1000 to a concentration of 0.20 mol / L ammonia and 4 g / L polyethylene glycol PEG1000, respectively, stirring to dissolve, and then adding a precipitant to adjust the pH to 10.5;

[0050] (3) The mixed salt solution, precipitant and complexing agent are simultaneously added dropwise to the reactor for coprecipitation reaction. During the reaction, the pH is controlled to be maintained at 10.5, the reaction temperature is maintained at 50°C, the speed of the reactor is 900 r / min, and the addition rate of the complexing agent is controlled to be a molar ratio of 0.20:1 to the metal ion added to the mixed salt solution per unit time; when the particle size D50 of the material in the reactor grows to 5-12 μm, the reaction is stopped and aged at 50°C for 6 h;

[0051] (4) The product is centrifuged, washed, and dried to obtain a macroporous spherical manganese-rich precursor.

[0052] The 2500x electron microscope image of the manganese-rich precursor prepared by the method of Example 1 is as follows: Figure 1 As shown, its 10000 times electron microscope image is as follows Figure 2 As shown by Figure 1 and Figure 2 It can be seen that the thickness of the primary flake particles of the manganese-rich precursor is about 30 nm and the pore diameter is about 380 nm.

[0053] Example 2

[0054] A method for preparing a manganese-rich precursor comprises the following steps:

[0055] (1) nickel chloride, manganese chloride, and cobalt chloride were weighed and dissolved in deionized water at a molar ratio of Ni:Mn:Co of 0.40:0.5:0.1 to prepare a mixed salt solution with a total concentration of 2 mol / L;

[0056] Weigh NaOH and dissolve it in deionized water to prepare a 4 mol / L solution as a precipitant;

[0057] Weigh ammonia water and dissolve it in deionized water to prepare a solution with a total concentration of 1 mol / L as a complexing agent;

[0058] (2) Adding pure water to a reactor filled with an inert atmosphere, adding ammonia water and polyethylene glycol PEG1000 to a concentration of 0.40 mol / L ammonia and 6 g / L polyethylene glycol PEG2000, respectively, stirring to dissolve, and then adding a precipitant to adjust the pH to 10;

[0059] (3) The mixed salt solution, precipitant and complexing agent are simultaneously added dropwise to the reactor for co-precipitation reaction. During the reaction, the pH is maintained at 10, the reaction temperature is maintained at 50°C, the speed of the reactor is 800 r / min, and the addition rate of the complexing agent is controlled so that the molar ratio of the metal ions added to the mixed salt solution per unit time is 0.20:1; when the particle size D50 of the material in the reactor grows to 5-12 μm, the reaction is stopped and aged at 50°C for 4 h;

[0060] (4) The product is centrifuged, washed, and dried to obtain a macroporous spherical manganese-rich precursor.

[0061] Example 3

[0062] A method for preparing a manganese-rich precursor comprises the following steps:

[0063] (1) nickel nitrate, manganese nitrate, and cobalt nitrate were weighed and dissolved in deionized water at a molar ratio of Ni:Mn:Co of 0.20:0.6:0.2 to prepare a mixed salt solution with a total concentration of 2 mol / L;

[0064] Weigh NaOH and dissolve it in deionized water to prepare a 4 mol / L solution as a precipitant;

[0065] Weigh ammonia water and dissolve it in deionized water to prepare a solution with a total concentration of 1 mol / L as a complexing agent;

[0066] (2) Adding pure water to a reactor filled with an inert atmosphere, adding ammonia water and polyethylene glycol PEG1000 to a concentration of 0.10 mol / L ammonia and 2 g / L polyethylene glycol PEG400, respectively, stirring to dissolve, and then adding a precipitant to adjust the pH to 9.5;

[0067] (3) The mixed salt solution, precipitant and complexing agent are simultaneously added dropwise to the reactor for coprecipitation reaction. During the reaction process, the pH is controlled to be maintained at 9.5, the reaction temperature is maintained at 50°C, the speed of the reactor is 800 r / min, and the addition rate of the complexing agent is controlled to be a molar ratio of 0.10:1 to the metal ion added to the mixed salt solution per unit time; when the particle size D50 of the material in the reactor grows to 5-12 μm, the reaction is stopped and aged at 50°C for 8 hours;

[0068] (4) The product is centrifuged, washed, and dried to obtain a macroporous spherical manganese-rich precursor.

[0069] Example 4

[0070] A method for preparing a manganese-rich precursor comprises the following steps:

[0071] (1) nickel acetate, manganese acetate, and cobalt acetate were weighed and dissolved in deionized water at a molar ratio of Ni:Mn:Co of 0.10:0.5:0.4 to prepare a mixed salt solution with a total concentration of 2 mol / L;

[0072] Weigh NaOH and dissolve it in deionized water to prepare a 4 mol / L solution as a precipitant;

[0073] Weigh ammonia water and dissolve it in deionized water to prepare a solution with a total concentration of 1 mol / L as a complexing agent;

[0074] (2) Add pure water to a reactor filled with an inert atmosphere, add ammonia water and polyethylene glycol PEG1000 to a concentration of 0.30 mol / L ammonia and 10 g / L polyethylene glycol PEG600:800 (mass ratio of 1:1), stir and dissolve, and then add a precipitant to adjust the pH to 10;

[0075] (3) The mixed salt solution, precipitant and complexing agent are simultaneously added dropwise to the reactor for coprecipitation reaction. During the reaction, the pH is maintained at 10, the reaction temperature is maintained at 50°C, the speed of the reactor is 500 r / min, and the addition rate of the complexing agent is controlled so that the molar ratio of the metal ions added to the mixed salt solution per unit time is 0.30:1; when the particle size D50 of the material in the reactor grows to 5-12 μm, the reaction is stopped and aged at 50°C for 6 h;

[0076] (4) The product is centrifuged, washed, and dried to obtain a macroporous spherical manganese-rich precursor.

[0077] Example 5

[0078] A method for preparing a manganese-rich precursor comprises the following steps:

[0079] (1) nickel sulfate and manganese sulfate were weighed and dissolved in deionized water at a molar ratio of Ni to Mn of 0.10:0.9 to prepare a mixed salt solution with a total concentration of 2 mol / L;

[0080] Weigh NaOH and dissolve it in deionized water to prepare a 4 mol / L solution as a precipitant;

[0081] Weigh ammonia water and dissolve it in deionized water to prepare a solution with a total concentration of 1 mol / L as a complexing agent;

[0082] (2) Adding pure water to a reactor filled with an inert atmosphere, adding ammonia water and polyethylene glycol PEG1000 to a concentration of 0.10 mol / L ammonia and 1 g / L polyethylene glycol PEG1500, respectively, stirring to dissolve, and then adding a precipitant to adjust the pH to 9.5;

[0083] (3) The mixed salt solution, precipitant and complexing agent are simultaneously added dropwise to the reactor for coprecipitation reaction. During the reaction, the pH is controlled to be maintained at 9.5, the reaction temperature is maintained at 40°C, the speed of the reactor is 1000 r / min, and the addition rate of the complexing agent is controlled to be a molar ratio of 0.10:1 to the metal ion added to the mixed salt solution per unit time; when the particle size D50 of the material in the reactor grows to 5-12 μm, the reaction is stopped and aged at 40°C for 4 h;

[0084] (4) The product is centrifuged, washed, and dried to obtain a macroporous spherical manganese-rich precursor.

[0085] As a comparison with the above embodiment 1, the present invention provides comparative examples 1-3 corresponding to the above embodiment 1, which are described in detail below:

[0086] Comparative Example 1

[0087] A method for preparing a manganese-rich precursor comprises the following steps:

[0088] (1) nickel sulfate, manganese sulfate, and cobalt sulfate were weighed and dissolved in deionized water at a molar ratio of Ni:Mn:Co of 0.30:0.6:0.1 to prepare a mixed salt solution with a total concentration of 2 mol / L;

[0089] Weigh NaOH and dissolve it in deionized water to prepare a 4 mol / L solution as a precipitant;

[0090] Weigh ammonia water and dissolve it in deionized water to prepare a solution with a total concentration of 1 mol / L as a complexing agent;

[0091] (2) adding pure water to a reactor filled with an inert atmosphere, adding ammonia water to a concentration of 0.20 mol / L ammonia, and then adding a precipitant to adjust the pH to 10.5;

[0092] (3) The mixed salt solution, precipitant and complexing agent are simultaneously added dropwise to the reactor for coprecipitation reaction. During the reaction, the pH is controlled to be maintained at 10.5, the reaction temperature is maintained at 50°C, the speed of the reactor is 800 r / min, and the addition rate of the complexing agent is controlled to be a molar ratio of 0.20:1 to the metal ion added to the mixed salt solution per unit time; when the particle size D50 of the material in the reactor grows to 5-12 μm, the reaction is stopped and aged at 50°C for 6 h;

[0093] (4) The product is centrifuged, washed, and dried to obtain a manganese-rich precursor.

[0094] Comparative Example 2

[0095] Except that polyvinyl pyrrolidone is used instead of polyethylene glycol PEG1000 in step (2), the rest is the same as Example 1.

[0096] Comparative Example 3

[0097] Except that the pH value in steps (2) and (3) is 11, the rest is the same as in Example 1.

[0098] The 2500x electron microscope image of the manganese-rich precursor prepared by the method of Comparative Example 1 is as follows: Figure 3 As shown, its 10000 times electron microscope image is as follows Figure 4 As shown, by Figure 3 and Figure 4 The manganese-rich precursor in Example 1 Figure 1 and Figure 2 By comparison and the data in Table 1, it can be seen that the manganese-rich precursor prepared by the method in Comparative Example 1 has thicker primary flaky particles, rougher secondary sphere surfaces, and poorer sphericity than the manganese-rich precursor prepared by the method in Example 1.

[0099] Similarly, as shown in Table 1, the manganese-rich precursors prepared in Examples 2-5, which regulate the precursor synthesis process, have thinner primary flake particles and larger pores than the manganese-rich precursors prepared in Comparative Examples 1, 2, and 3. The corresponding sintered materials have small, uniform primary particle sizes and high porosity.

[0100] Table 1 Physical properties of manganese-rich precursors prepared in Examples 1-5 and Comparative Examples 1-3

[0101]

[0102]

[0103] The above-mentioned physical property test methods are as follows:

[0104] Pore ​​diameter and primary particle thickness: obtained by field emission scanning electron microscopy;

[0105] Specific surface area: obtained by testing with a specific surface area meter;

[0106] Tap density: obtained by testing with a tap density meter.

[0107] The present invention provides a manganese-rich precursor, which is prepared by any of the above-mentioned manganese-rich precursor preparation methods. The primary particle thickness of the manganese-rich precursor is 10-60nm, the pore diameter is 100nm-1μm, and the BET is 20-60m 2 / g.

[0108] The present invention provides a positive electrode material, which is prepared by sintering the above-mentioned manganese-rich precursor.

[0109] The manganese-rich precursors prepared in Example 1 and Comparative Example 1 were mixed evenly with lithium carbonate at a molar ratio of transition metal to lithium of 1:1.4, placed in a muffle furnace, and heated to 500°C at a heating rate of 5°C / min in an air atmosphere for 5 hours, then heated to 900°C and kept for 12 hours, and finally naturally cooled to room temperature to prepare two lithium-rich manganese-based positive electrode materials. The primary particles of the sintered material of Example 1 are relatively uniform, with a particle size of about 0.2-0.5 μm, and there are many pores between the primary particles, while the primary particles of the sintered material of Comparative Example 1 are long flakes of uneven size, with a thickness of 0.2-0.5 μm (average 0.3 μm) and a length of 0.5-2 μm (average 1 μm).

[0110] The present invention also provides a lithium ion battery comprising the above-mentioned positive electrode material.

[0111] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced with equivalents, without departing from the spirit and substance of the claims of the present invention; and such modifications or replacements remain within the scope of the claims of the present invention.

Claims

1. A manganese-rich precursor, characterized in that The general chemical formula of the manganese-rich precursor is: Mn x Ni y Co 1-x-y (OH)2, where 0.5≤x≤0.9, 0.1≤y≤0.4; The manganese-rich precursor is a spherical or quasi-spherical secondary particle with a macroporous structure formed by agglomeration of flaky primary particles; Wherein, the manganese-rich precursor has the following characteristics: (1) The pore size of the secondary particles is 100nm-1μm; (2) The thickness of the flaky primary particles is 10-60 nm; (3) The BET of the manganese-rich precursor is 20-60m 2 / g; The preparation method of the manganese-rich precursor comprises the following steps: In a container filled with an inert atmosphere, pure water, a dispersant, and a complexing agent are added to prepare a base liquid, wherein the concentration of the dispersant in the base liquid is controlled to be 1-10 g / L, the concentration of ammonia is controlled to be 0.1-0.4 mol / L, and a precipitant is added to adjust the pH value of the base liquid to 9.5-10.5; wherein the dispersant is one or more polyethylene glycols having a relative molecular weight between 400 and 2000; A metal salt solution, a precipitant and a complexing agent are simultaneously added to a bottom liquid for reaction, and the pH value is controlled to remain unchanged during the reaction process. The reaction is stopped when the particle size D50 of the precipitated slurry grows to 5-12 μm. The precipitated slurry is centrifuged, washed and dried to obtain a manganese-rich precursor.

2. A method for preparing the manganese-rich precursor according to claim 1, characterized in that: The steps include: In a container filled with an inert atmosphere, pure water, a dispersant, and a complexing agent are added to prepare a base liquid, wherein the concentration of the dispersant in the base liquid is controlled to be 1-10 g / L, the concentration of ammonia is controlled to be 0.1-0.4 mol / L, and a precipitant is added to adjust the pH value of the base liquid to 9.5-10.5; wherein the dispersant is one or more polyethylene glycols having a relative molecular weight between 400 and 2000; A metal salt solution, a precipitant and a complexing agent are simultaneously added to a bottom liquid for reaction, and the pH value is controlled to remain unchanged during the reaction process. The reaction is stopped when the particle size D50 of the precipitated slurry grows to 5-12 μm. The precipitated slurry is centrifuged, washed and dried to obtain a manganese-rich precursor.

3. The preparation method according to claim 2, characterized in that The steps include: (1) preparing a metal salt solution, a precipitant, and a complexing agent: the total concentration of metal ions in the metal salt solution is 1-4 mol / L, the concentration of the precipitant is 2-8 mol / L, and the concentration of the complexing agent is 1-8 mol / L; (2) adding pure water, a dispersant, and a complexing agent into a container filled with an inert atmosphere to prepare a base solution, controlling the concentration of the dispersant in the base solution to be 1-10 g / L and the concentration of ammonia to be 0.1-0.4 mol / L, and adding a precipitant to adjust the pH value of the base solution to 9.5-10.5; wherein the dispersant is one or more polyethylene glycols having a relative molecular weight between 400 and 2000; (3) adding a metal salt solution, a precipitant, and a complexing agent to the bottom liquid simultaneously for reaction, controlling the pH to remain constant during the reaction, and stopping the reaction until the particle size D50 of the precipitated slurry grows to 5-12 μm; and discharging the slurry after aging; (4) Post-treatment: centrifuging, washing, and drying the slurry to obtain a manganese-rich precursor.

4. The preparation method according to claim 3, characterized in that In step (1), the metal salt includes a manganese salt, a nickel salt and an optional cobalt salt; the manganese salt is one or more selected from manganese sulfate, manganese chloride, manganese nitrate and manganese acetate; the nickel salt is one or more selected from nickel sulfate, nickel nitrate, nickel acetate and nickel chloride; the cobalt salt is one or more selected from cobalt sulfate, cobalt chloride, cobalt nitrate and cobalt acetate; the molar ratio of Mn, Ni and Co is x:y:1-xy, wherein 0.5≤x≤0.9, 0.1≤y≤0.

4.

5. The preparation method according to claim 3, characterized in that In step (1), the precipitant is one or more selected from a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution and a lithium hydroxide aqueous solution.

6. The preparation method according to claim 3, characterized in that In step (1), the complexing agent is one or more selected from ammonia water, ammonium bicarbonate aqueous solution and ammonium carbonate aqueous solution.

7. The preparation method according to claim 3, characterized in that In step (3), the reaction conditions include: reaction temperature of 40-60°C, stirring speed of 500-1000 rpm, reaction time of 10-30 h; controlling the ammonia content in the reaction system to 0.1-0.4 mol / L; The aging temperature is 20-60°C, and the aging time is 1-12h.

8. The preparation method according to claim 3, characterized in that In step (4), the drying conditions include: a drying temperature of 80-120° C. and a drying time of 8-24 h.

9. A positive electrode material, characterized in that It is prepared by sintering the manganese-rich precursor according to claim 1 or the manganese-rich precursor prepared by the preparation method according to any one of claims 2 to 8.

10. A lithium ion battery, characterized in that: Contains the positive electrode material according to claim 9.

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