阅读说明：本技术 一种镍锰酸锂材料、其制备方法和用途 (Lithium nickel manganese oxide material, and preparation method and application thereof ) 是由 施泽涛 乔齐齐 李子郯 江卫军 王鹏飞 郭丰 杨红新 于 2021-08-19 设计创作，主要内容包括：本发明提供了一种镍锰酸锂材料、其制备方法和用途,所述制备方法包括：对镍锰酸锂基体材料进行锰源包覆,制备得到所述镍锰酸锂材料。本发明通过对镍锰酸锂基体材料进行锰源包覆,锰源包覆能够与材料的表面的残碱进行反应,并对材料包覆,一方面有效降低材料表面的残碱,另一方面形成稳定的锰锂化合物包覆层,有效提高材料的循环性能和倍率性能,避免常规方法中对镍锰酸锂材料水洗去除残碱,破坏材料表面,导致循环性能和倍率性能降低的问题。(The invention provides a lithium nickel manganese oxide material, a preparation method and application thereof, wherein the preparation method comprises the following steps: and carrying out manganese source coating on the lithium nickel manganese oxide matrix material to prepare the lithium nickel manganese oxide material. According to the method, the manganese source coating is carried out on the lithium nickel manganese oxide base material, the manganese source coating can react with residual alkali on the surface of the material, and the material is coated, so that on one hand, the residual alkali on the surface of the material is effectively reduced, on the other hand, a stable manganese lithium compound coating layer is formed, the cycle performance and the rate capability of the material are effectively improved, and the problem that the cycle performance and the rate capability are reduced due to the fact that the residual alkali is removed by washing the lithium nickel manganese oxide material in a conventional method and the surface of the material is damaged is solved.)

1. The preparation method of the lithium nickel manganese oxide material is characterized by comprising the following steps:

and carrying out manganese source coating on the lithium nickel manganese oxide matrix material to prepare the lithium nickel manganese oxide material.

2. The preparation method according to claim 1, wherein the preparation method of the lithium nickel manganese oxide matrix material comprises the following steps: mixing and calcining a lithium source and a nickel-manganese precursor to obtain a lithium nickel manganese oxide matrix material;

preferably, the lithium source comprises LiOH;

preferably, the lithium source has a D50 ≦ 10 μm;

preferably, the chemical formula of the nickel-manganese precursor is Ni_xMn_y(OH)₂Wherein x is more than or equal to 0.85 and less than or equal to 0.95, y is more than or equal to 0.05 and less than or equal to 0.15, and x + y is 1;

preferably, the molar ratio of the lithium element in the lithium source to the sum of the metal elements in the nickel-manganese precursor is (1.05-1.2): 1;

preferably, the stirring speed of the mixing is 1500-2500 rpm;

preferably, the mixing time is 5-15 min.

3. The production method according to claim 2, wherein the calcination is performed in an oxygen atmosphere;

preferably, the oxygen volume concentration of the oxygen atmosphere is more than or equal to 95 percent;

preferably, the oxygen flow of the oxygen atmosphere is 5-10L/min.

4. The preparation method according to claim 2 or 3, wherein the temperature of the calcination is 720 to 850 ℃;

preferably, the temperature rise rate of the calcination is 1-3 ℃/min;

preferably, the calcining temperature is 8-12 h;

preferably, the calcining is followed by crushing and sieving;

preferably, the crushing mode of the crushing and sieving is ultracentrifugal grinding;

preferably, the mesh number of the crushing and sieving screen is 300-400 meshes.

5. Root of herbaceous plantThe method of any one of claims 1 to 4, wherein the manganese source comprises MnO, MnO₂、Mn₃O₄Or Mn (CH)₃COO)₂One or a combination of at least two of;

preferably, the coating amount of the coated manganese element is 4000-10000 ppm by mass of the base material.

6. The method according to any one of claims 1 to 5, wherein the temperature of the coating is 300 to 700 ℃;

preferably, the coating time is 4-7 h;

preferably, the temperature rise rate of the coating is 1-3 ℃/min.

7. The preparation method according to any one of claims 1 to 6, comprising in particular the steps of:

according to the method, a lithium source and a nickel-manganese precursor are mixed for 5-15 min at 1500-2500 rpm according to the molar ratio of the lithium element in the lithium source to the total metal element in the nickel-manganese precursor (1.05-1.5): 1, and then calcined for 8-12 h at 720-850 ℃ in an oxygen atmosphere with the oxygen volume concentration of more than or equal to 95% and the oxygen flow of 5-10L/min at the heating rate of 1-3 ℃/min, crushed and sieved at 300-400 meshes to obtain a base material;

and (II) coating the manganese source on the base material prepared in the step (I) at the temperature of 300-700 ℃ for 4-7 h, wherein the heating rate is 1-3 ℃/min, and the lithium nickel manganese oxide material with the coating amount of 4000-10000 ppm is prepared.

8. A lithium nickel manganese oxide material, which is characterized in that the lithium nickel manganese oxide material is coated with a manganese source coating layer, and the lithium nickel manganese oxide material is prepared by the preparation method of the lithium nickel manganese oxide material according to any one of claims 1 to 7.

9. The lithium nickel manganese oxide material of claim 8, wherein the lithium nickel manganese oxide material has a D50 of 6-13 μm;

preferably, the specific surface area of the lithium nickel manganese oxide material is 0.3-1.5 m²/g；

Preferably, the pH value of the lithium nickel manganese oxide material is less than or equal to 11.8.

10. A battery, which is characterized by comprising a positive electrode, a negative electrode and a separator, wherein the positive electrode material in the positive electrode adopts the lithium nickel manganese oxide material in the claim 8 or 9.

Technical Field

The invention belongs to the technical field of batteries, and particularly relates to a lithium nickel manganese oxide material, and a preparation method and application thereof.

Background

With the continuous deterioration of the environment and the gradual shortage of fossil fuels, people's demand for energy is more and more developing towards cleanness and portability. The lithium ion secondary battery has the advantages of no pollution, large energy storage, portability and the like, and is widely applied to equipment such as mobile phone batteries, computers, cameras and the like. With the development of the technology, the lithium ion battery with high energy density is more and more widely applied to the hybrid electric vehicle, even the pure electric vehicle, and provides power for the travel of people.

The nickel manganese lithium cobaltate ternary positive electrode material has the advantages of high energy density, good cycle performance, safety, environmental protection and the like, and is an important direction for the research of the current battery positive electrode material. However, the cobalt resource is less in storage, so that the cobalt is expensive and easy to control, and the cobalt has great pollution to the environment. Therefore, the development of the cobalt-free lithium nickel manganese oxide material has great advantages in the aspects of controlling cost and enhancing market tolerance. At present, the residual alkali on the surface of the material can be reduced to a lower value by a water washing method for the cobalt-free high-nickel material, but the material circulation and the capacity are greatly reduced after the water washing. The main reason is that although the washing can effectively reduce the residual alkali, the surface of the material after washing is often damaged, the interface is smooth, the surface structure is unstable, and the side reaction with the electrolyte is easy to occur, so that the capacity and the cycle performance of the material are further influenced.

CN105355905A discloses a preparation method of a high-voltage modified lithium ion battery cathode material lithium nickel manganese oxide, wherein a manganese source and a nickel salt material are mixed to prepare a nickel manganese precursor by a sol-gel method, the nickel manganese precursor, a lithium salt and doped metal cations are mixed by a three-dimensional inclined mixer, and are subjected to presintering, high-temperature sintering, then metal oxide is added to coat, and finally, a finished product of lithium nickel manganese oxide is obtained through low-temperature sintering, airflow crushing and grading. The product produced by the method has the advantages of moderate granularity, uniform distribution, high tap density, and good high-temperature performance and cycle performance.

CN106920952A discloses a preparation method of a modified lithium nickel manganese oxide positive electrode material, which comprises the following steps: firstly, mixing a cerium-iron composite oxide with a lithium salt, a nickel salt and a manganese source, then performing ball milling dispersion, and then performing vacuum drying to obtain a precursor of the cerium-iron composite oxide coated lithium nickel manganese oxide material; and calcining the precursor at the constant temperature of 700-1000 ℃ for 5-20 h in the air atmosphere, and naturally cooling to obtain the modified lithium nickel manganese oxide cathode material. The cerium-iron composite oxide is coated on the surface of the lithium nickel manganese oxide to form a stable protective layer, so that the contact between the electrolyte and the lithium nickel manganese oxide can be effectively reduced, the oxidative decomposition of the electrolyte on the surface of the anode is reduced, the chemical stability of the anode material in a battery system is improved, and the cycle performance is improved.

The existing lithium nickel manganese oxide materials have high surface residual alkali, poor material performance and complex preparation process, so that the problems that how to ensure low surface residual alkali and good material electrical performance can be ensured under the condition of ensuring simple preparation process of the lithium nickel manganese oxide materials become urgent need to be solved at present.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a lithium nickel manganese oxide material, a preparation method and application thereof, and the method for reducing surface residual alkali without washing the lithium nickel manganese oxide material is adopted, and a manganese-containing compound is used for reacting with residual alkali on the surface of the material, so that the residual alkali on the surface of the material is reduced, a stable lithium manganese compound is formed, and the circulation and the multiplying power of the material are improved.

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

in a first aspect, the invention provides a preparation method of a lithium nickel manganese oxide material, which comprises the following steps:

and carrying out manganese source coating on the lithium nickel manganese oxide matrix material to prepare the lithium nickel manganese oxide material.

According to the invention, the manganese source coating is carried out on the lithium nickel manganese oxide matrix material, the manganese source coating can react with residual alkali on the surface of the material, and the material is coated, so that on one hand, the residual alkali on the surface of the material is effectively reduced, and on the other hand, a stable manganese lithium compound coating layer is formed, so that the cycle performance and the rate capability of the material are effectively improved, the problem that the cycle performance and the rate capability are reduced due to the fact that the residual alkali is removed by washing the lithium nickel manganese oxide material in a conventional method and the surface of the material is damaged is solved, and the lithium nickel manganese oxide coating method has the characteristics of simple preparation process, industrial production and the like.

Illustratively, a method for preparing a nickel-manganese precursor is provided, which comprises: nickel salt and manganese salt are mixed according to the molar ratio of nickel element to manganese element of 8: 2, mixing, and coprecipitating at pH 11.5 to obtain nickel-manganese precursor, wherein the nickel salt can be nickel sulfate, and the manganese salt can be manganese sulfate.

As a preferred technical scheme of the invention, the preparation method of the lithium nickel manganese oxide matrix material comprises the following steps: and mixing and calcining the lithium source and the nickel-manganese precursor to obtain the lithium nickel manganese oxide matrix material.

Preferably, the lithium source comprises LiOH.

Preferably, the lithium source has a D50 ≦ 10 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm.

Preferably, the chemical formula of the nickel-manganese precursor is Ni_xMn_y(OH)₂Where 0.85. ltoreq. x.ltoreq.0.95, for example x is 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94 or 0.95, 0.05. ltoreq. y.ltoreq.0.15, for example y is 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14 or 0.15, x + y being 1.

According to the invention, the nickel-manganese precursor with high nickel content is adopted, so that the prepared nickel lithium manganate material has the characteristic of high specific capacity.

Preferably, the molar ratio of the lithium element in the lithium source to the sum of the metal elements in the nickel-manganese precursor is (1.05-1.2): 1, for example, 1.05:1, 1.10:1, 1.15:1 or 1.20:1, and it is to be noted that the metal elements in the nickel-manganese precursor include nickel element and manganese element, and the sum of the metal elements is the molar sum of the nickel element and the manganese element.

Preferably, the mixing is performed at a stirring speed of 1500 to 2500rpm, such as 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm, 2000rpm, 2100rpm, 2200rpm, 2300rpm, 2400rpm or 2500 rpm.

Preferably, the mixing time is 5-15 min, such as 5min, 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min or 15 min.

In a preferred embodiment of the present invention, the calcination is performed in an oxygen atmosphere.

Preferably, the oxygen atmosphere has an oxygen concentration of 95% by volume or more, such as 95%, 96%, 97%, 98%, 99% or 99.99%.

According to the invention, the calcination is carried out in an oxygen atmosphere, the volume concentration of oxygen is more than or equal to 95%, the material has a good layered structure, the reaction of the precursor, lithium salt and oxygen is more sufficient, meanwhile, the residual alkali can be reduced, if the volume concentration is less than 95%, the structure of the synthetic material is unstable, the Li/Ni mixed discharge is increased, and the residual alkali is increased.

Preferably, the oxygen flow rate of the oxygen atmosphere is 5-10L/min, such as 5.0L/min, 5.5L/min, 6.0L/min, 6.5L/min, 7.0L/min, 7.5L/min, 8.0L/min, 8.5L/min, 9.0L/min, 9.5L/min or 10.0L/min.

In a preferred embodiment of the present invention, the calcination temperature is 720 to 850 ℃, for example, 720 ℃, 730 ℃, 740 ℃, 750 ℃, 760 ℃, 770 ℃, 780 ℃, 790 ℃, 800 ℃, 810 ℃, 820 ℃, 830 ℃, 840 ℃ or 850 ℃.

Preferably, the heating rate of the calcination is 1-3 ℃/min, such as 1.0 ℃/min, 1.2 ℃/min, 1.4 ℃/min, 1.6 ℃/min, 1.8 ℃/min, 2.0 ℃/min, 2.2 ℃/min, 2.4 ℃/min, 2.6 ℃/min, 2.8 ℃/min or 3.0 ℃/min.

Preferably, the calcination temperature is 8-12 h, such as 8.0h, 8.5h, 9.0h, 9.5h, 10.0h, 10.5h, 11.0h, 11.5h or 12.0 h.

Preferably, the calcination is followed by crushing and sieving.

It is well known to those skilled in the art that after calcination, the material is cooled to room temperature and then crushed and sieved.

Preferably, the crushing mode of the crushing and screening is ultracentrifugal grinding.

Preferably, the mesh number of the crushing and sieving screen is 300-400 meshes, such as 300 meshes, 310 meshes, 320 meshes, 330 meshes, 340 meshes, 350 meshes, 360 meshes, 370 meshes, 380 meshes, 390 meshes or 400 meshes.

As a preferred embodiment of the present invention, the manganese source includes MnO and MnO₂、Mn₃O₄Or Mn (CH)₃COO)₂Or a combination of at least two thereof.

Preferably, the coating amount of the manganese element after coating is 4000 to 10000ppm, for example, 4000ppm, 4500ppm, 5000ppm, 5500ppm, 6000ppm, 6500ppm, 7000ppm, 7500ppm, 8000ppm, 8500ppm, 9000ppm, 9500ppm or 10000ppm, based on the mass of the base material as a whole.

According to the invention, the coating amount of the coated manganese element is controlled to be 4000-10000 ppm, so that the effects of reducing residual alkali of the material and improving the electrochemical performance are achieved, if the coating amount is lower than 4000ppm, the problem of less reduction of the residual alkali exists, and if the coating amount is higher than 10000ppm, the problem of more reduction of the capacity exists.

In a preferred embodiment of the present invention, the coating temperature is 300 to 700 ℃, for example, 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃ or 700 ℃.

Preferably, the coating time is 4-7 h, such as 4.0h, 4.4h, 4.8h, 5.2h, 5.6h, 6.0h, 6.4h, 6.8h or 7.0 h.

Preferably, the temperature rise rate of the coating is 1-3 ℃/min, for example, 1.0 ℃/min, 1.2 ℃/min, 1.4 ℃/min, 1.6 ℃/min, 1.8 ℃/min, 2.0 ℃/min, 2.2 ℃/min, 2.4 ℃/min, 2.6 ℃/min, 2.8 ℃/min or 3.0 ℃/min.

As a preferred technical scheme of the invention, the preparation method specifically comprises the following steps:

according to the method, a lithium source and a nickel-manganese precursor are mixed for 5-15 min at 1500-2500 rpm according to the molar ratio of the lithium element in the lithium source to the total metal element in the nickel-manganese precursor (1.05-1.5): 1, and then calcined for 8-12 h at 720-850 ℃ in an oxygen atmosphere with the oxygen volume concentration of more than or equal to 95% and the oxygen flow of 5-10L/min at the heating rate of 1-3 ℃/min, crushed and sieved at 300-400 meshes to obtain a base material;

and (II) coating the manganese source on the base material prepared in the step (I) at the temperature of 300-700 ℃ for 4-7 h, wherein the heating rate is 1-3 ℃/min, and the lithium nickel manganese oxide material with the coating amount of 4000-10000 ppm is prepared.

In a second aspect, the invention provides a lithium nickel manganese oxide material, wherein the lithium nickel manganese oxide material is coated with a manganese source coating layer, and is prepared by the preparation method of the lithium nickel manganese oxide material in the first aspect.

In a preferred embodiment of the present invention, the lithium nickel manganese oxide material has a D50 of 6 to 13 μm, for example, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm, 10.0 μm, 10.5 μm, 11.0 μm, 11.5 μm, 12.0 μm, 12.5 μm or 13.0 μm.

Preferably, the specific surface area of the lithium nickel manganese oxide material is 0.3-1.5 m²A/g, of, for example, 0.3m²/g、0.4m²/g、0.5m²/g、0.6m²/g、0.7m²/g、0.8m²/g、0.9m²/g、1.0m²/g、1.1m²/g、1.2m²/g、1.3m²/g、1.4m²G or 1.5m²/g。

Preferably, the pH of the lithium nickel manganese oxide material is less than or equal to 11.8, such as 10.0, 10.2, 10.4, 10.6, 10.8, 11.0, 11.2, 11.4, 11.6, or 11.8.

In a third aspect, the invention provides a battery, which comprises a positive electrode, a negative electrode and a diaphragm, wherein the positive electrode material in the positive electrode adopts the lithium nickel manganese oxide material in the second aspect.

The recitation of numerical ranges herein includes not only the above-recited numerical values, but also any numerical values between non-recited numerical ranges, and is not intended to be exhaustive or to limit the invention to the precise numerical values encompassed within the range for brevity and clarity.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, the manganese source coating is carried out on the lithium nickel manganese oxide matrix material, the manganese source coating can react with residual alkali on the surface of the material, and the material is coated, so that on one hand, the residual alkali on the surface of the material is effectively reduced, and on the other hand, a stable manganese lithium compound coating layer is formed, so that the cycle performance and the rate capability of the material are effectively improved, the problem that the cycle performance and the rate capability are reduced due to the fact that the residual alkali is removed by washing the lithium nickel manganese oxide material in a conventional method and the surface of the material is damaged is solved, and the lithium nickel manganese oxide coating method has the characteristics of simple preparation process, industrial production and the like.

Drawings

FIG. 1 is a graph comparing discharge capacity and cycle performance of examples 1, 4, 5, 6 and 1 according to the present invention.

Detailed Description

In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.

Example 1

The embodiment provides a preparation method of a lithium nickel manganese oxide material, which specifically comprises the following steps:

according to the molar ratio of the lithium element to the sum of the metal elements in the nickel-manganese precursor of 1.05:1, the LiOH with the D50 of 5 mu m and the Ni are mixed_0.9Mn_0.1(OH)₂Mixing at 2000rpm for 10min, calcining at 720 deg.C for 10h in oxygen atmosphere with oxygen volume concentration of 98% and oxygen flow of 5L/min, heating at 2 deg.C/min, ultracentrifugal grinding, and sieving at 350 mesh to obtain base material;

and (II) performing MnO coating on the substrate material prepared in the step (I) at the temperature of 500 ℃ for 5.5 hours, wherein the heating rate is 2 ℃/min, and preparing the lithium nickel manganese oxide material with the manganese source coating amount of 6000 ppm.

Wherein the D50 of the lithium nickel manganese oxide material is 9 mu m, and the specific surface area is 0.9m²Per g, pH 11.55.

Example 2

The embodiment provides a preparation method of a lithium nickel manganese oxide material, which specifically comprises the following steps:

according to the molar ratio of the lithium element to the sum of the metal elements in the nickel-manganese precursor of 1:1, D50 is LiOH and Ni with the diameter of 2 mu m_0.85Mn_0.15(OH)₂Mixing at 1500rpm for 15min, calcining at 750 deg.C for 12h in oxygen atmosphere with oxygen volume concentration of 98.5% and oxygen flow of 7.5L/min at a temperature rise rate of 1 deg.C/min, ultracentrifuging, grinding, and sieving with 300 mesh sieve to obtain base material;

(II) Mn is carried out on the matrix material prepared in the step (I) at the temperature of 300 DEG C₃O₄And coating for 7h, wherein the heating rate is 1 ℃/min, and the lithium nickel manganese oxide material with the manganese source coating amount of 4000ppm is prepared.

Wherein the D50 of the lithium nickel manganese oxide material is 13 mu m, and the specific surface area is 1.5m²Per g, pH 11.8.

Example 3

The embodiment provides a preparation method of a lithium nickel manganese oxide material, which specifically comprises the following steps:

according to the molar ratio of the lithium element to the sum of the metal elements in the nickel-manganese precursor of 1.15:1, the LiOH with the D50 of 10 mu m and the Ni are mixed_0.95Mn_0.05(OH)₂Mixing at 2500rpm for 5min, calcining at 850 deg.C for 8h in oxygen atmosphere with oxygen volume concentration of 99% and oxygen flow of 10L/min, heating at 3 deg.C/min, ultracentrifugal grinding, and sieving with 400 mesh sieve to obtain base material;

(II) MnO treatment of the base material prepared in step (I) at 700 ℃₂And (3) coating for 4h, wherein the heating rate is 3 ℃/min, and the lithium nickel manganese oxide material with the manganese source coating amount of 10000ppm is prepared.

Wherein the D50 of the lithium nickel manganese oxide material is 6 mu m, and the specific surface area is 0.3m²Per g, pH 11.35.

Example 4

This example provides a method for preparing a lithium nickel manganese oxide material, which is different from example 1 in that in step (ii), the amount of manganese source coated in the lithium nickel manganese oxide material is 4000ppm, and the rest of the steps and parameters are exactly the same as those in example 1.

Example 5

This example provides a method for preparing a lithium nickel manganese oxide material, which is different from example 1 in that in step (ii), the amount of manganese source coated in the lithium nickel manganese oxide material is 8000ppm, and the rest of the steps and parameters are exactly the same as those in example 1.

Example 6

This example provides a method for preparing a lithium nickel manganese oxide material, which is different from example 1 in that in step (ii), the amount of manganese source coated in the lithium nickel manganese oxide material is 10000ppm, and the rest of the steps and parameters are completely the same as those in example 1.

Example 7

This example provides a method for preparing a lithium nickel manganese oxide material, which is different from example 1 in that in step (ii), the amount of manganese source coated in the lithium nickel manganese oxide material is 3000ppm, and the rest of the steps and parameters are exactly the same as those in example 1.

Example 8

This example provides a method for preparing a lithium nickel manganese oxide material, which is different from example 1 in that in step (ii), the amount of manganese source coated in the lithium nickel manganese oxide material is 12000ppm, and the rest of the steps and parameters are exactly the same as those in example 1.

Example 9

This example provides a method for preparing lithium nickel manganese oxide material, which is different from example 1 in that in step (i), the concentration of oxygen atmosphere is 90%, and the rest of the steps and parameters are exactly the same as those in example 1.

Comparative example 1

This comparative example provides a method for preparing a lithium nickel manganese oxide material, which is different from example 1 in that the manganese source coating in step (II) is not performed, the manganese source coating amount is 0ppm, and the rest of the steps and parameters are completely the same as those in example 1.

The invention also provides a battery which comprises a positive electrode, a negative electrode and a diaphragm, wherein the positive electrode material in the positive electrode adopts the lithium nickel manganese oxide material in the embodiment.

The lithium nickel manganese oxide materials in the above examples and comparative examples were subjected to a residual base number (LiOH + Li) by a potentiometric titration method₂CO₃) The results of the detection and residual alkali value test are shown in Table 1.

And (3) performing electric fastening assembly on the lithium nickel manganese oxide materials in the examples and the comparative examples by adopting a CR2032 shell, wherein the cathode material: sp: the mass ratio of the PVDF glue solution is 92:4:4, and the solid content of the PVDF glue solution is 6.25%.

And carrying out electrochemical performance test on the prepared electricity deduction, wherein the test method comprises the following steps:

the test is carried out by using blue electric charge and discharge equipment, and the test items comprise: 0.1C/1C capacity test, 1C50 week charge-discharge cycle test.

Electrochemical performance test results are shown in table 2, and comparative graphs of discharge capacity and cycle performance of examples 1 to 9 and comparative example 1 are shown in fig. 1.

TABLE 1

	Residual base number (ppm)
		Example 1	4263
Example 2	6230
		Example 3	3700
Example 4	5500
		Example 5	3650
Example 6	3320
		Example 7	8360
Example 8	2980
		Example 9	6802
Comparative example 1	10500

TABLE 2

From the above table, it can be seen that:

(1) in example 1, the residual alkali value is lower than that in example 7 and higher than that in example 8, but the electrical property of example 1 is better than that in examples 7 and 8, compared with examples 7 and 8, it can be seen that the present invention has the effects of reducing the residual alkali of the material and improving the electrochemical performance by controlling the coating amount of the manganese element after coating to 4000 to 10000ppm, and if the coating amount is lower than 4000ppm, the residual alkali is less reduced, and if the coating amount is higher than 10000ppm, the capacity is much reduced.

(2) Compared with the example 9, the residual alkali value of the example 1 is lower than that of the example 9, and the electrical property is better than that of the example 9, therefore, the invention can be seen that the invention has better layered structure by calcining in the oxygen atmosphere, the volume concentration of oxygen is more than or equal to 95%, the material has better layered structure, the reaction of the precursor, lithium salt and oxygen is more sufficient, meanwhile, the residual alkali can be reduced, if the volume concentration is lower than 95%, the structure of the synthesized material is unstable, the Li/Ni mixed discharge is increased, and the residual alkali is improved.

(3) Example 1 compared with comparative example 1, the residual alkali value of example 1 was lower than that of comparative example 1, and the electrical properties of example 1 are better than those of comparative example 1, and it can be seen from the combination of fig. 1 that after Mn coating, the capacity performance and the cycle performance of the material are improved, in the embodiment, the capacity is improved by 2-4 mAh/g, the cycle performance is improved by 2-3%, therefore, the invention carries out manganese source coating on the lithium nickel manganese oxide matrix material, the manganese source coating can react with residual alkali on the surface of the material, and the material is coated, so that residual alkali on the surface of the material is effectively reduced, a stable manganese-lithium compound coating layer is formed, the cycle performance and rate capability of the material are effectively improved, the problem that the cycle performance and rate capability are reduced due to the fact that the surface of the material is damaged by removing the residual alkali through water washing of the lithium nickel manganese oxide material in the conventional method is solved, and the preparation method has the characteristics of simple preparation process, industrial production and the like.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.