阅读说明：本技术 富锂锰基前驱体及其制备方法、富锂锰基正极材料及其制备方法 (Lithium-rich manganese-based precursor and preparation method thereof, lithium-rich manganese-based positive electrode material and preparation method thereof ) 是由 彭工厂 郭志豪 王昊 瞿美臻 李林 葛武杰 于 2021-08-18 设计创作，主要内容包括：本发明属于锂电池领域,提供了一种富锂猛基前驱体的制备方法,包括如下步骤：S1.配置溶液：分别配置过渡金属盐溶液、碱性溶液、络合溶液A和络合溶液B；S2.共沉淀反应：将步骤S1制备得到的过渡金属盐溶液和碱性溶液分别缓慢加入反应釜中进行反应；在反应进行的第一阶段同时向反应釜中缓慢加入络合溶液A；在反应进行的第二阶段同时向反应釜中缓慢加入络合溶液B；S3.后处理。上述方法能够合成颗粒表面光滑、球形度好、颗粒致密性好、粒度分布均匀的前驱体材料,且合成过程中不使用含氨络合剂。本发明还提供了上述方法制备的富锂锰基前驱体以及由该前驱体制备的富锂锰基正极材料及其制备方法。(The invention belongs to the field of lithium batteries, and provides a preparation method of a lithium-rich manganese-based precursor, which comprises the following steps: s1, preparing a solution: respectively preparing a transition metal salt solution, an alkaline solution, a complexing solution A and a complexing solution B; s2, coprecipitation reaction: slowly adding the transition metal salt solution and the alkaline solution prepared in the step S1 into a reaction kettle respectively for reaction; slowly adding the complexing solution A into the reaction kettle at the first stage of reaction; slowly adding the complexing solution B into the reaction kettle at the second stage of the reaction; and S3, post-processing. The method can synthesize the precursor material with smooth particle surface, good sphericity, good particle compactness and uniform particle size distribution, and does not use an ammonia-containing complexing agent in the synthesis process. The invention also provides the lithium-rich manganese-based precursor prepared by the method, a lithium-rich manganese-based positive electrode material prepared from the precursor and a preparation method of the lithium-rich manganese-based positive electrode material.)

1. A preparation method of a lithium-rich manganese-based precursor is characterized by comprising the following steps:

s1, preparing a solution: respectively preparing a transition metal salt solution, an alkaline solution, a complexing solution A and a complexing solution B; the complexing solution A is prepared by adding a complexing agent A into deionized water, wherein the complexing agent A is selected from one or more of citrate, 5 sulfosalicylate or salicylate; the complexing solution B is prepared by adding a complexing agent B into deionized water, wherein the complexing agent B is selected from one or more of succinate, tartrate or lactate;

s2, coprecipitation reaction: slowly adding the transition metal salt solution and the alkaline solution prepared in the step S1 into a reaction kettle respectively for reaction; slowly adding the complexing solution A into the reaction kettle at the first stage of reaction; slowly adding the complexing solution B into the reaction kettle at the second stage of the reaction; wherein the reaction time of the first stage is 3-5 h, the reaction time of the second stage is 5-7 h, and the total reaction time is 8-12 h;

s3, post-processing: and after the reaction is finished, aging, filtering, washing and drying to obtain the lithium-rich manganese-based precursor.

2. The method for preparing a lithium-rich manganese-based precursor according to claim 1, wherein in step S2, the pH of the reaction system is controlled to be maintained at 7.5-8.5 during the reaction by adjusting the addition amount of said alkaline solution and the addition amount of said complexing solution a, or by adjusting the addition amount of said alkaline solution and the addition amount of said complexing solution B.

3. The method for preparing the lithium-rich manganese-based precursor according to claim 2, wherein in step S1, the transition metal salt solution is prepared by: according to the proportion of Ni: co: weighing a nickel source, a cobalt source and a manganese source according to the molar ratio of Mn to Mn of 0.10-0.15: 0.50-0.60, adding the nickel source, the cobalt source and the manganese source into deionized water, and preparing the mixture into a solution with the concentration of transition metal ions of 1-4 mol L^-1A transition metal salt solution of (a).

4. The method for preparing a Li-rich manganese-based precursor according to any one of claims 1 to 3, wherein in step S1, said alkaline solution is prepared from sodium carbonate and deionized water, and the concentration of said alkaline solution is 1-4 mol L^-1。

5. The method for preparing a Li-rich manganese-based precursor according to any one of claims 1 to 3, wherein in step S1, the concentration of said complexing solution A is 0.01-0.1 mol L^-1(ii) a The concentration of the complexing solution B is 0.01-0.2 mol L^-1。

6. The method for preparing a lithium-rich manganese-based precursor according to claim 1, wherein in step S2, the reaction temperature is controlled to be 40-60 ℃, and the stirring speed is 800-1300 rpm.

7. The method of claim 3, wherein the nickel source is NiSO₄·6H₂O, the cobalt source is CoSO₄·7H₂O, the manganese source is MnSO₄·H₂O。

8. A lithium-rich manganese-based precursor, characterized by being prepared by the preparation method of any one of claims 1 to 7.

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

(1) mixing the lithium-rich manganese-based precursor of any one of claims 1 to 7 with a lithium source in the ratio of total transition metal elements: preparing lithium at a molar ratio of Li to 1: 1.1-1.5;

(2) putting the substance obtained in the step (1) into a mortar for grinding for 1.5-3 h, and fully and uniformly mixing to obtain a uniform mixture;

(3) and (3) placing the uniform mixture obtained in the step (2) in a tubular furnace, pre-sintering at the temperature of 400-600 ℃ for 3-7h, and then sintering at the temperature of 700-900 ℃ for 8-15h to obtain the lithium-rich manganese-based anode material.

10. A lithium-rich manganese-based positive electrode material, characterized by being prepared by the preparation method of claim 9.

Technical Field

The invention relates to the field of lithium batteries, in particular to a lithium-rich manganese-based precursor and a preparation method thereof, and a lithium-rich manganese-based positive electrode material and a preparation method thereof.

Background

The lithium ion battery is widely applied to various fields from 3C electronic products to electric automobiles and the like due to the advantages of light weight, high energy density, no memory effect, long cycle life, environmental friendliness and the like. With the development of the times, people have increasingly greater demands for higher-capacity and safer lithium ion batteries. The lithium-rich manganese-based cathode material is regarded as the next generation of lithium ion battery cathode material with the most potential due to the advantages of ultrahigh specific discharge capacity of more than 250mAh g-1, low cost, no toxicity, high thermal stability and the like.

The method is mature at present and easy to realize large-scale production, can realize uniform mixing at atomic level, has simple equipment and easy operation, and can realize regulation and control on the granularity and the appearance of the product.

Because the solubility of the carbonates of nickel, cobalt and manganese are different greatly (as shown in table 1), a complexing agent is usually added during the coprecipitation reaction to ensure that the carbonates of nickel, cobalt and manganese can be precipitated simultaneously.

TABLE 1 solubility of Nickel cobalt manganese carbonate

At present, when the lithium-rich manganese-based positive electrode material precursor is prepared by a coprecipitation method, the most commonly used complexing agent is ammonia water, and the ammonia water is used as the most commonly used complexing agent, is an inorganic liquid with irritation, corrosivity and toxicity, and is easily oxidized into NO^2-、NO^3-And other nitrogen-containing compounds, causing water, soil and air pollution. Therefore, from the viewpoint of environmental protection, reducing the use of ammonia can reduce the emission of nitrogen-containing compounds and improve the environment; in view of production costs, reducing the use of ammonia may reduce the cost of processing nitrogenous chemicals in the production process. Therefore, the method for most directly and effectively reducing pollution and cost is used for researching the use of the ammonia-free complexing agent in the process of preparing the lithium-rich manganese-based positive electrode material precursor by the coprecipitation method.

Chinese patent No. CN109081384A discloses a composite complexing agent and a method for preparing a lithium ion power battery anode precursor material, chinese patent No. CN112661202A discloses a lithium ion battery anode material modified by a coprecipitation method, a preparation method and an application thereof, and these two patents respectively disclose that a composite complexing agent formed by citrate and glutamate or citrate and glycinate is used to replace the existing complexing agent containing ammonia, thereby solving the environmental problem caused by the complexing agent containing ammonia. However, when the composite complexing agent in the above patent is used to synthesize the lithium-rich manganese-based precursor, the inventor finds that the prepared material has rough particle surface, poor sphericity, poor particle compactness and uneven particle size distribution, thereby resulting in poor electrochemical performance of the prepared cathode material.

In summary, it is a technical problem to be further solved by those skilled in the art to provide a preparation method of a lithium-rich manganese-based precursor, which can synthesize particles with smooth surface, good sphericity, good compactness, uniform particle size distribution, and does not use an ammonia-containing complexing agent in the synthesis process.

Disclosure of Invention

The first purpose of the invention is to provide a preparation method of a lithium-rich manganese-based precursor, which can synthesize a precursor material with smooth particle surface, good sphericity, good compactness and uniform particle size distribution, and does not use an ammonia-containing complexing agent in the synthesis process.

The second purpose of the invention is to provide the lithium-rich manganese-based precursor synthesized by the method, which has good electrochemical performance.

The third purpose of the invention is to provide a method for preparing a lithium-rich manganese-based cathode material from the precursor, and further provide the lithium-rich manganese-based cathode material prepared by the method.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of a lithium-rich manganese-based precursor comprises the following steps:

s1, preparing a solution: respectively preparing a transition metal salt solution, an alkaline solution, a complexing solution A and a complexing solution B; the complexing solution A is prepared by adding a complexing agent A into deionized water, wherein the complexing agent A is selected from one or more of citrate, 5 sulfosalicylate or salicylate; the complexing solution B is prepared by adding a complexing agent B into deionized water, wherein the complexing agent B is selected from one or more of succinate, tartrate or lactate;

s2, coprecipitation reaction: slowly adding the transition metal salt solution and the alkaline solution prepared in the step S1 into a reaction kettle respectively for reaction; slowly adding the complexing solution A into the reaction kettle at the first stage of reaction; slowly adding the complexing solution B into the reaction kettle at the second stage of the reaction; wherein the reaction time of the first stage is 3-5 h, the reaction time of the second stage is 5-7 h, and the total reaction time is 8-12 h;

s3, post-processing: and after the reaction is finished, aging, filtering, washing and drying to obtain the lithium-rich manganese-based precursor.

The invention also provides the lithium-rich manganese-based precursor prepared by the preparation method.

The invention also provides a method for preparing the lithium-rich manganese-based anode material from the lithium-rich manganese-based precursor, which comprises the following steps:

(1) mixing the lithium-rich manganese-based precursor with a lithium source according to the total transition metal elements: preparing lithium at a molar ratio of Li to 1: 1.1-1.5;

(2) putting the substance obtained in the step (1) into a mortar for grinding for 1.5-3 h, and fully and uniformly mixing to obtain a uniform mixture;

(3) and (3) placing the uniform mixture obtained in the step (2) in a tubular furnace, pre-sintering at the temperature of 400-600 ℃ for 3-7h, and then sintering at the temperature of 700-900 ℃ for 8-15h to obtain the lithium-rich manganese-based anode material.

The invention also provides the lithium-rich manganese-based positive electrode material prepared by the method.

The invention has the beneficial effects that:

1. the production cost is low: when the lithium-rich manganese-based precursor is prepared, the ammonia-free complexing agent is adopted to replace the ammonia-containing complexing agent in the prior art, so that the environmental problem caused by the ammonia-containing complexing agent is avoided, the denitrification treatment is not needed, and the process complexity is reduced, thereby reducing the production cost;

2. the particle appearance is good: the invention adopts the method that the complexing solution A with strong complexing ability is added in the early stage of the reaction, and the nucleation rate is reduced in the nucleation reaction period of the crystal grains; when the solution reaches a saturated state in the later reaction period, adding a complexing solution B with weak complexing ability to promote the better growth of crystal grains; by adding different types of complexing agents at different periods, smooth generation of particles can be ensured, the prepared particles have smooth surfaces, good sphericity, good compactness and uniform particle size distribution, and the lithium-rich manganese-based anode material with good electrochemical performance can be prepared.

3. The electrochemical performance is good: according to the invention, multiple ammonia-free complexing agents are added in batches, the formed precursor has a good appearance, and the first-circle specific discharge capacity and the first-circle coulombic efficiency of the obtained anode material are effectively improved.

Drawings

Fig. 1 is an SEM image of lithium-rich manganese-based precursors prepared in examples 1, 4 and 5 of the present invention, wherein a is an SEM image of the lithium-rich manganese-based precursor of example 1, b is an SEM image of the lithium-rich manganese-based precursor of example 4, and c is an SEM image of the lithium-rich manganese-based precursor of example 5;

fig. 2 is an SEM image of the lithium-rich manganese-based precursor prepared in example 1, example 4 and example 5 of the present invention, wherein a is an SEM image of the lithium-rich manganese-based precursor of example 1, b is an SEM image of the lithium-rich manganese-based precursor of example 4, and c is an SEM image of the lithium-rich manganese-based precursor of example 5;

fig. 3 is SEM images of lithium-rich manganese-based precursors prepared in comparative example 1 and comparative example 2 of the present invention, wherein a is an SEM image of the lithium-rich manganese-based precursor in comparative example 1, and b is an SEM image of the lithium-rich manganese-based precursor in comparative example 2.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the present invention is further described with reference to specific embodiments below.

The embodiment provides a preparation method of a lithium-rich manganese-based precursor, which comprises the following steps:

s1, preparing a solution: respectively preparing a transition metal salt solution, an alkaline solution, a complexing solution A and a complexing solution B; the complexing solution A is prepared by adding a complexing agent A into deionized water, wherein the complexing agent A is selected from one or more of citrate, 5 sulfosalicylate or salicylate; the complexing solution B is prepared by adding a complexing agent B into deionized water, wherein the complexing agent B is selected from one or more of succinate, tartrate or lactate;

preferably, the complexing agent A is citrate, and further preferably trisodium citrate dihydrate; the complexing agent B is preferably one or more of sodium succinate, sodium tartrate or sodium lactate;

s2, coprecipitation reaction: slowly adding the transition metal salt solution and the alkaline solution prepared in the step S1 into a reaction kettle respectively for reaction; slowly adding the complexing solution A into the reaction kettle at the first stage of reaction; slowly adding the complexing solution B into the reaction kettle at the second stage of the reaction; wherein the reaction time of the first stage is 3-5 h, the reaction time of the second stage is 5-7 h, and the total reaction time is 8-12 h;

in the present application, the reaction directly enters the second stage after the first stage is finished;

in the early stage of reaction, the crystal nucleus forming period is adopted, and in the reaction stage, the complexing solution A with strong complexing capability is used, so that the nucleation rate can be reduced, and the crystal nucleus can be well formed; in the second stage of reaction, the solution is saturated, and at the moment, the complexing solution B with weak complexing ability is added, so that the growth of crystal grains can be facilitated, the crystal grains are promoted to be compact and smooth, the balling effect is good, and the particle size distribution is uniform;

s3, post-processing: and after the reaction is finished, aging, filtering, washing and drying to obtain the precursor of the lithium-rich manganese-based positive electrode material.

Specifically, after the reaction is finished, aging is carried out for 12-40 h.

Preferably, in step S2, the pH value of the reaction system is controlled to be maintained at 7.5-8.5 during the whole reaction process by adjusting the addition amount of the alkaline solution and the addition amount of the complexing solution a, or adjusting the addition amount of the alkaline solution and the addition amount of the complexing solution B.

Lithium-rich manganese-based precursor of the present application, due to its Mn²⁺The high content of Mn may be caused by strong alkaline environment²⁺And oxidizing, so that the lithium-rich manganese-based precursor is prepared under the condition of strictly controlling the pH value to be 7.5-8.5 and having low alkalinity. In addition, under the condition of the pH value, the coprecipitation effect of the three transition metals is optimal, and the formed particles can be more uniform.

Further preferably, in step S1, the preparation method of the metal salt solution is: according to the proportion of Ni: co: weighing a nickel source, a cobalt source and a manganese source according to the molar ratio of Mn to Mn of 0.10-0.15: 0.50-0.60, adding the nickel source, the cobalt source and the manganese source into deionized water, and preparing 1-4 mol L of transition metal ions^-1A transition metal salt solution of (a).

In step S1, an alkaline solution is prepared by adding deionized water into sodium carbonate, and the concentration of the alkaline solution is 1-4 mol L^-1。

In step S1, the concentration of the complexing solution A is 0.01-0.1 mol L^-1(ii) a The concentration of the complexing solution B is 0.01-0.2 mol L^-1。

In order to stably control the pH value within the range required by the reaction, weak base carbonate is adopted to prepare an alkaline solution; and the concentrations of the transition metal salt solution, the alkaline solution, the complexing solution A and the complexing solution B are reasonably set. The reaction process can be stably controlled, and the generated particles are smooth and compact, have good sphericity and high yield.

In the step S2, the reaction temperature is controlled to be 40-60 ℃, and the stirring speed is 800-1300 rpm.

The preferred nickel source for this application is NiSO₄·6H₂O, cobalt source is CoSO₄·7H₂O, manganese source is MnSO₄·H₂O。

The application also provides the lithium-rich manganese-based precursor prepared by the method.

In addition, the application also provides a preparation method of the lithium-rich manganese-based positive electrode material, which comprises the following steps:

(1) mixing the lithium-rich manganese-based precursor with a lithium source according to the total transition metal elements: preparing lithium at a molar ratio of Li to 1: 1.1-1.5; the lithium source of the present application is preferably lithium carbonate or lithium hydroxide;

(2) putting the substance obtained in the step (1) into a mortar for grinding for 1.5-3 h, and fully and uniformly mixing to obtain a uniform mixture;

(3) and (3) placing the uniform mixture obtained in the step (2) in a tubular furnace, pre-sintering at the temperature of 400-600 ℃ for 3-7h, and then sintering at the temperature of 700-900 ℃ for 8-15h to obtain the lithium-rich manganese-based anode material.

The application also provides the lithium-rich manganese-based positive electrode material prepared by the preparation method.

Example 1

The embodiment provides a preparation method of a lithium-rich manganese-based precursor, which comprises the following steps:

s1, preparing a solution:

transition metal salt solution: according to the proportion of Ni: co: molar ratio of Mn 0.13:0.13:0.54 NiSO was accurately weighed₄·6H₂O、CoSO₄·7H₂O and MnSO₄·H₂O, adding the obtained product into deionized water to prepare a solution with the concentration of transition metal ions of 2mol L^-1A transition metal salt solution of (a);

alkaline solution: accurately weighing sodium carbonate, adding deionized water to prepare sodium carbonate with the concentration of 2mol L^-1The alkaline solution of (4);

complexing solution A: accurately weighing trisodium citrate dihydrate (Na)₃C₆H₅O₆·2H₂O) is prepared into trisodium citrate dihydrate with the concentration of 0.05mol L^-1The complexing solution A of (a);

and (3) complexing solution B: accurately weighing sodium tartrate (C)₄H₄Na₂O₆) The concentration of the sodium tartrate is 0.1mol L^-1The complexing solution B of (1);

s2, coprecipitation reaction:

respectively adding the transition metal salt solution and the alkaline solution prepared in the step S1 into a reaction kettle filled with 300mL of deionized water as a base solution by using a peristaltic pump; adding the complexing solution A into a reaction kettle through a peristaltic pump at the same time in the first stage of reaction; directly entering a second stage after the first stage is finished; in the second stage of the reaction, slowly adding the complexing solution B into the reaction kettle through a peristaltic pump; wherein the reaction time of the first stage is 4h, the reaction time of the second stage is 6h, and the total reaction time is 10 h; controlling the pH value of a reaction system to be kept at 7.5-8.5 in the whole reaction process, controlling the reaction temperature to be 50-60 ℃, and controlling the stirring speed to be 1200 rpm;

s3, post-processing: and after the reaction is finished, aging for 20h, filtering, washing and drying to obtain the lithium-rich manganese-based precursor F1.

Example 2

The embodiment provides a preparation method of a lithium-rich manganese-based precursor, which comprises the following steps:

s1, preparing a solution:

transition metal salt solution: according to the proportion of Ni: co: the molar ratio of Mn to Mn is 0.15:0.15:0.60, and NiSO is accurately weighed₄·6H₂O、CoSO₄·7H₂O and MnSO₄·H₂O, adding the obtained product into deionized water to prepare a solution with the concentration of transition metal ions of 4mol L^-1A transition metal salt solution of (a);

alkaline solution: accurately weighing sodium carbonate, adding deionized water to prepare sodium carbonate with the concentration of 4mol L^-1The alkaline solution of (4);

complexing solution A: accurately weighing trisodium citrate dihydrate (Na)₃C₆H₅O₆·2H₂O) is prepared into trisodium citrate dihydrate with the concentration of 0.1mol L^-1The complexing solution A of (a);

and (3) complexing solution B: accurately weighing sodium tartrate (C)₄H₄Na₂O₆) The concentration of the sodium tartrate is 0.2mol L^-1The complexing solution B of (1);

s2, coprecipitation reaction:

respectively adding the transition metal salt solution and the alkaline solution prepared in the step S1 into a reaction kettle filled with 300mL of deionized water as a base solution by using a peristaltic pump; adding the complexing solution A into a reaction kettle through a peristaltic pump at the same time in the first stage of reaction; directly entering a second stage after the first stage is finished; in the second stage of the reaction, slowly adding the complexing solution B into the reaction kettle through a peristaltic pump; wherein the reaction time of the first stage is 3h, the reaction time of the second stage is 5h, and the total reaction time is 8 h; controlling the pH value of a reaction system to be kept at 7.5-8.5 in the whole reaction process, controlling the reaction temperature to be 50-60 ℃, and controlling the stirring speed to be 1200 rpm;

s3, post-processing: and after the reaction is finished, aging for 20h, filtering, washing and drying to obtain the lithium-rich manganese-based precursor F2.

Example 3

The embodiment provides a preparation method of a lithium-rich manganese-based precursor, which comprises the following steps:

s1, preparing a solution:

transition metal salt solution: according to the proportion of Ni: co: the molar ratio of Mn to Mn is 0.11:0.11:0.50 and Ni SO is accurately weighed₄·6H₂O、CoSO₄·7H₂O and MnSO₄·H₂O, adding the obtained product into deionized water to prepare a solution with the concentration of transition metal ions of 1mol L^-1A transition metal salt solution of (a);

alkaline solution: accurately weighing sodium carbonate, adding deionized water to prepare sodium carbonate with the concentration of 1mol L^-1The alkaline solution of (4);

complexing solution A: accurately weighing the lemonTrisodium citrate (Na)₃C₆H₅O₆·2H₂O) was prepared in a concentration of 0.01mol L^-1The complexing solution A of (a);

and (3) complexing solution B: accurately weighing sodium tartrate (C)₄H₄Na₂O₆) Is prepared to have a concentration of 0.01mol L^-1The complexing solution B of (1);

s2, coprecipitation reaction:

respectively adding the transition metal salt solution and the alkaline solution prepared in the step S1 into a reaction kettle filled with 300mL of deionized water as a base solution by using a peristaltic pump; adding the complexing solution A into a reaction kettle through a peristaltic pump at the same time in the first stage of reaction; after the first stage is finished, the reaction directly enters a second stage, and in the second stage of reaction, the complexing solution B is slowly added into the reaction kettle through a peristaltic pump; wherein the reaction time of the first stage is 5h, the reaction time of the second stage is 7h, and the total reaction time is 12 h; controlling the pH value of a reaction system to be kept at 7.5-8.5 in the whole reaction process, controlling the reaction temperature to be 50-60 ℃, and controlling the stirring speed to be 1200 rpm;

s3, post-processing: and after the reaction is finished, aging for 20h, filtering, washing and drying to obtain the lithium-rich manganese-based precursor F3.

Example 4

This example provides a method for preparing a lithium-rich manganese-based precursor, which is different from example 1 in that: in step S1, sodium tartrate (C) in the complex solution B is prepared₄H₄Na₂O₆) Replacement with sodium succinate (C)₄H₄Na₂O₄)。

And preparing the lithium-rich manganese-based precursor F4.

Example 5

This example provides a method for preparing a lithium-rich manganese-based precursor, which is different from example 1 in that: in step S1, sodium tartrate (C) in the complex solution B is prepared₄H₄Na₂O₆) Replaced by sodium lactate (C)₃H₅O₃Na)。

And preparing the lithium-rich manganese-based precursor F5.

Example 6

This example provides a method for preparing a lithium-rich manganese-based precursor, which is different from example 1 in that: in step S1, trisodium citrate dihydrate (Na) in the complex solution a is prepared₃C₆H₅O₆·2H₂O) was replaced with sodium salicylate.

And preparing the lithium-rich manganese-based precursor F6.

Example 7

This example provides a method for preparing a lithium-rich manganese-based precursor, which is different from example 1 in that: in step S1, trisodium citrate dihydrate (Na) in the complex solution a is prepared₃C₆H₅O₆·2H₂O) was replaced with 5 sodium sulfosalicylate.

And preparing the lithium-rich manganese-based precursor F7.

Comparative example 1

The embodiment provides a preparation method of a lithium-rich manganese-based precursor, which comprises the following steps:

s1, preparing a solution:

transition metal salt solution: according to the proportion of Ni: co: molar ratio of Mn 0.13:0.13:0.54 NiSO was accurately weighed₄·6H₂O、CoSO₄·7H₂O and MnSO₄·H₂O, adding the obtained product into deionized water to prepare a solution with the concentration of transition metal ions of 2mol L^-1A transition metal salt solution of (a);

alkaline solution: accurately weighing sodium carbonate, adding deionized water to prepare sodium carbonate with the concentration of 2mol L^-1The alkaline solution of (4);

complexing solution: accurately weighing trisodium citrate dihydrate (Na)₃C₆H₅O₆·2H₂O) is prepared into trisodium citrate dihydrate with the concentration of 0.05mol L^-1The complexing solution of (a);

s2, coprecipitation reaction:

respectively adding the transition metal salt solution and the alkaline solution prepared in the step S1 into a reaction kettle filled with 300mL of deionized water as a base solution by using a peristaltic pump; slowly adding the complexing solution into the reaction solution by a peristaltic pump in the reaction process, wherein the total reaction time is 10 hours; controlling the pH value of a reaction system to be kept at 7.5-8.5 in the whole reaction process, controlling the reaction temperature to be 50-60 ℃, and controlling the stirring speed to be 1200 rpm;

s3, post-processing: and after the reaction is finished, aging for 20h, filtering, washing and drying to obtain the lithium-rich manganese-based precursor K1.

Comparative example 2

The present comparative example provides a method for preparing a lithium-rich manganese-based precursor, which is different from comparative example 1 in that: in step S1, trisodium citrate dihydrate (Na) in the complexing solution is prepared₃C₆H₅O₆·2H₂O) replacement with trisodium citrate dihydrate (Na)₃C₆H₅O₆·2H₂O) and sodium tartrate (C)₄H₄Na₂O₆) And the molar ratio of trisodium citrate dihydrate to sodium tartrate is 1: 2.

And preparing the lithium-rich manganese-based precursor K2.

Experimental example 1SEM

The lithium-rich manganese-based precursors F1, F4, F5, K1, and K2 obtained in example 1, example 4, example 5, comparative example 1, and comparative example 2 described above were subjected to morphology observation using a scanning electron microscope, respectively.

The observation results are shown in the attached figures 1 to 3; wherein fig. 1a and 2a are SEM images of F1, fig. 1b and 2b are SEM images of F4, fig. 1c and 2c are SEM images of F5, fig. 3a is a SEM image of K1, and fig. 3b is a SEM image of K2.

The results show that the particles in fig. 1a, 1b and 1c are smooth, have good compactness and good sphericity, and fig. 2a, 2b and 2c show that the particle size distribution uniformity is good, the sphericity is good and the surface is smooth; the particles in fig. 3a and 3b are clearly less spherical, rough in surface, less dense and have a poor particle size distribution.

From this it can be seen that: the preparation method is favorable for forming the lithium-rich manganese-based precursor particles with good appearance.

Experimental example 1 electrochemical Performance test

The lithium-rich manganese-based precursors of examples 1 to 7 and the lithium-rich manganese-based precursors of comparative examples 1 to 2 were prepared into lithium-rich manganese-based positive electrode materials according to the following methods, respectively, and assembled into batteries, and the electrochemical performance of the obtained batteries was tested, with the test results shown in table 2:

the preparation method of the lithium-rich manganese-based positive electrode material comprises the following steps:

(1) and mixing the precursor of the lithium-rich manganese-based positive electrode material with lithium carbonate according to the total transition metal elements: preparing lithium by the molar ratio of Li to 1: 1.3;

(2) putting the substance obtained in the step (1) into a mortar for grinding for 2 hours, and fully and uniformly mixing to obtain a uniform mixture;

(3) and (3) placing the uniform mixture obtained in the step (2) into a tubular furnace, pre-sintering for 5 hours at 500 ℃, and then sintering for 11 hours at 800 ℃ to obtain the lithium-rich manganese-based anode material.

The prepared lithium-rich manganese-based positive electrode material is prepared by the following steps of: conductive carbon black: PVDF 8: 1:1 preparing positive electrode slurry of the battery and assembling the positive electrode slurry into the battery.

Table 2 electrochemical performance test results of each example and comparative example

From the results in table 2, it can be known that the first-turn specific discharge capacity and the first-turn coulombic efficiency of the battery prepared from the precursor prepared by the preparation method of the present application are obviously superior to those of the comparative examples 1 and 2.

In conclusion, the preparation method can prepare the lithium-rich manganese-based precursor material with good particle morphology and the lithium-rich manganese-based anode material with good electrochemical performance, and the whole preparation process has low production cost, easy operation control and good practical application value.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.