阅读说明：本技术 正极材料前驱体、正极材料及其制备方法和应用 (Positive electrode material precursor, positive electrode material, and preparation method and application thereof ) 是由 张宁 万江涛 张勇杰 刘满库 刘海松 江卫军 于 2021-09-29 设计创作，主要内容包括：本发明涉及锂离子电池技术领域,具体涉及正极材料前驱体、正极材料及其制备方法和应用。本发明提供的正极材料前驱体,其化学通式为Mn-(X)Fe-(1-X)(OH)-(2),其中0.45＜X＜0.65。本发明提供的前驱体采用共沉淀法进行制备,与现有技术相比,其有利于锰铁两种金属元素在体相中均匀分布,从而提升正极材料的综合性能,同时将锰铁两种金属元素进行组合,可有效解决传统正极材料锂镍混排导致的电化学性能衰退与安全性问题,降低前驱体与正极材料的制造与生产成本,减少资源的浪费与环境的破坏。(The invention relates to the technical field of lithium ion batteries, in particular to a precursor of a positive electrode material, the positive electrode material, and a preparation method and application thereof. The chemical general formula of the precursor of the cathode material provided by the invention is Mn X Fe 1‑X (OH) 2 Wherein X is more than 0.45 and less than 0.65. The precursor provided by the invention is prepared by adopting a coprecipitation method, and compared with the prior artCompared with the prior art, the method is beneficial to the uniform distribution of two metal elements of manganese and iron in a bulk phase, so that the comprehensive performance of the anode material is improved, and the combination of the two metal elements of manganese and iron can effectively solve the problems of electrochemical performance decline and safety caused by the mixed discharge of lithium and nickel in the traditional anode material, reduce the manufacturing and production costs of the precursor and the anode material, and reduce the waste of resources and the damage of the environment.)

1. The precursor of the cathode material is characterized in that the chemical general formula of the precursor is Mn_XFe_1-X(OH)₂Wherein X is more than 0.45 and less than 0.65.

2. A method for producing a precursor for a positive electrode material according to claim 1, comprising the steps of: mixing a metal salt solution, a reducing agent, a complexing agent and a hydroxide precipitator to carry out coprecipitation reaction to obtain a precursor of the positive electrode material; the metal salt is manganese salt or iron salt.

3. The method for producing a precursor for a positive electrode material according to claim 2, comprising the steps of:

1) respectively preparing a manganese salt solution, an iron salt solution and a hydroxide precipitator solution;

2) preparing a base solution containing a reducing agent and a complexing agent, and then adding a manganese salt solution, an iron salt solution and a hydroxide precipitator solution into the base solution to perform a coprecipitation reaction to obtain a precursor of the positive electrode material;

preferably, the molar concentration ratio of the manganese salt solution to the iron salt solution is (0.45-0.65): (0.35-0.55), wherein the sum of the molar concentrations of the manganese salt solution and the ferric salt solution is 1-3 mol/L;

the concentration of the hydroxide precipitant solution is 1-3 mol/L;

the concentration of the reducing agent in the base solution is 1-20ml/L, and the concentration of the complexing agent is 15-50 ml/L.

4. The method for preparing the precursor of the positive electrode material according to claim 3, wherein in the step 2), the manganese salt solution and the iron salt solution are added into the base solution at the same flow rate, and simultaneously the hydroxide precipitant solution is added to perform the coprecipitation reaction;

preferably, the coprecipitation reaction temperature is 35-50 ℃, the reaction time is 20-60h, the stirring speed is 200-1000rpm, and the pH value of the reaction solution is controlled to be 8-10.5 in the reaction process;

the manganese salt is divalent manganese salt and is selected from manganese sulfate and/or manganese chloride; the iron salt is a ferrous salt selected from ferrous sulfate and/or ferrous chloride;

the hydroxide precipitating agent is selected from sodium hydroxide and/or potassium hydroxide;

the base solution is obtained by adding a reducing agent and a complexing agent into water, wherein the reducing agent is hydrazine hydrate, and the complexing agent is ammonia water with the mass concentration of 20-30%; preferably, the complexing agent is ammonia water with the mass concentration of 25%;

and 2) after the reaction is finished, washing and drying the obtained reaction product.

5. A positive electrode material prepared from the precursor according to claim 1 or the precursor prepared by the preparation method according to any one of claims 2 to 4;

the chemical general formula of the cathode material is Li (Li)_0.02Mn_XFe_0.98-X)O₂Wherein X is more than 0.44 and less than 0.64, and the anode material is of a laminated structure.

6. A method for preparing the positive electrode material according to claim 5, comprising the steps of: mixing and calcining a precursor of the positive electrode material and a lithium source to obtain the positive electrode material;

the precursor of the positive electrode material is the precursor according to claim 1 or the precursor prepared by the preparation method according to any one of claims 2 to 4.

7. The method according to claim 6, wherein the calcining atmosphere is an oxygen-containing atmosphere, preferably, the calcining atmosphere is an air atmosphere or an oxygen atmosphere;

the calcination comprises primary calcination and secondary calcination which are sequentially carried out, wherein the primary calcination temperature is 400-600 ℃, the primary calcination time is 2-8h, the secondary calcination temperature is 700-900 ℃, and the calcination time is 10-20 h.

8. The production method according to claim 6 or 7, characterized in that the molar ratio of the lithium source to the positive electrode material precursor is (1.02-1.05):1, preferably, the lithium source is a lithium salt, preferably, the lithium salt is lithium hydroxide;

the method also comprises the step of crushing the material after the primary calcination between the primary calcination and the secondary calcination.

9. A battery positive electrode comprising the positive electrode material according to claim 5 or the positive electrode material produced by the production method according to any one of claims 6 to 8.

10. A lithium ion battery, wherein a positive electrode of the lithium ion battery is the battery positive electrode according to claim 9.

Technical Field

The invention relates to the technical field of lithium ion batteries, in particular to a precursor of a positive electrode material, the positive electrode material, and a preparation method and application thereof.

Background

Since the 21 st century, energy crisis and environmental problems have become two major problems that have plagued human development. Therefore, people are dedicated to research and develop clean renewable energy sources, such as wind energy, geothermal energy, tidal energy and the like. The importance of energy storage devices is highlighted by the need to store these renewable energy sources. Energy storage devices in the market currently dominate batteries, and lithium ion batteries dominate the market. The positive electrode material has obvious influence on the performance of the lithium ion battery as an important component of the lithium ion battery, so that the update iteration of the positive electrode material is crucial, the nickel-cobalt-manganese ternary material is taken as a main product in the current positive electrode material market, however, the nickel-cobalt-manganese ternary material also has many problems which cannot be solved, for example, the mixed discharge phenomenon of nickel and lithium is serious, which directly causes a large amount of gas generation in the charge and discharge process, thereby leading to a series of safety problems, and when the nickel content in the ternary material is increased, the problem is more serious; the currently-proven global reserve of cobalt element is limited, so that the cobalt element is relatively high in price, and the cobalt element also has radioactivity and toxicity, which can bring a series of environmental protection problems. The above problems will severely restrict the rapid development of the lithium battery industry.

In order to solve the above problems, in the prior art, a lithium iron manganese positive electrode material is developed, wherein a positive electrode material precursor is prepared by grinding acetate, however, in the precursor prepared by the method, two metal elements of manganese and iron are unevenly distributed in a bulk phase, and the obtained positive electrode material has limited comprehensive performance.

Disclosure of Invention

In order to overcome the problems, the invention provides a novel method for preparing a ferromanganese precursor and a positive electrode material thereof, the ferromanganese precursor is prepared by a coprecipitation method, the problem that two metal elements of ferromanganese are unevenly distributed in a material phase during dry preparation can be effectively solved, and the two metal elements of ferromanganese are combined so as to solve the problems of electrochemical performance degradation and safety caused by lithium-nickel mixed discharge of the traditional positive electrode material, reduce the manufacturing and production costs of the precursor and the positive electrode material, and prepare the precursor and the positive electrode material with low price, environmental friendliness and better performance.

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

a precursor of a positive electrode material has a chemical general formula of Mn_XFe_1-X(OH)₂Wherein X is more than 0.45 and less than 0.65.

Preferably, the average particle diameter of the precursor is 3 to 6 μm.

The invention also provides a preparation method of the anode material precursor, which comprises the following steps: mixing a metal salt solution, a reducing agent, a complexing agent and a hydroxide precipitator to carry out coprecipitation reaction to obtain a precursor of the positive electrode material; the metal salt is manganese salt or iron salt.

Preferably, the method comprises the following steps:

1) respectively preparing a manganese salt solution, an iron salt solution and a hydroxide precipitator solution;

2) preparing a base solution containing a reducing agent and a complexing agent, and then adding a manganese salt solution, an iron salt solution and a hydroxide precipitator solution into the base solution to carry out coprecipitation reaction, thereby obtaining the precursor of the positive electrode material.

Preferably, the first and second liquid crystal materials are,

the molar concentration ratio of the manganese salt solution to the iron salt solution is (0.45-0.65): (0.35-0.55), and the sum of the molar concentrations of the manganese salt solution and the ferric salt solution is 1-3 mol/L.

The concentration of the hydroxide precipitant solution is 1-3 mol/L.

The concentration of the reducing agent in the base solution is 1-20ml/L, and the concentration of the complexing agent is 15-50 ml/L.

Preferably, the molar ratio of the manganese salt to the iron salt in the reaction liquid in the step 2) is (0.45-0.65): (0.35-0.55).

Preferably, in the step 2), the manganese salt solution and the iron salt solution are added into the base solution at the same flow rate, and simultaneously, the hydroxide precipitator solution is added to carry out coprecipitation reaction; preferably, the flow rate is 100-.

The coprecipitation reaction temperature is 35-50 ℃, the reaction time is 20-60h, the stirring speed is 200-1000rpm, and the pH value of the reaction liquid is controlled to be 8-10.5 in the reaction process.

Preferably, the manganese salt is a divalent manganese salt selected from manganese sulfate and/or manganese chloride; the iron salt is a ferrous salt selected from ferrous sulfate and/or ferrous chloride;

the hydroxide precipitating agent is selected from sodium hydroxide and/or potassium hydroxide;

the base solution is obtained by adding a reducing agent and a complexing agent into water, wherein the reducing agent is hydrazine hydrate, and the complexing agent is ammonia water with the mass concentration of 20-30%; preferably, the complexing agent is ammonia water with the mass concentration of 25%;

preferably, the step 2) further comprises the steps of washing and drying the obtained reaction product after the reaction is finished.

Preferably, the reaction product is washed 3-5 times with ultrapure water and then dried at 110-130 ℃ for 15-20h, preferably at 120 ℃ for 18 h.

The invention also provides a positive electrode material prepared from the precursor or the precursor prepared by the preparation method.

Preferably, the chemical formula of the cathode material is Li (Li)_0.02Mn_XFe_0.98-X)O₂Wherein X is more than 0.44 and less than 0.64.

Preferably, the cathode material has a layered structure.

The invention also provides a preparation method of the cathode material, which comprises the following steps: mixing and calcining a precursor of the positive electrode material and a lithium source to obtain the positive electrode material;

the precursor of the cathode material is the precursor or the precursor prepared by the preparation method.

Preferably, the calcining atmosphere is an oxygen-containing atmosphere, and preferably, the calcining atmosphere is an air atmosphere or an oxygen atmosphere;

the calcination comprises primary calcination and secondary calcination which are sequentially carried out, wherein the primary calcination temperature is 400-600 ℃, the primary calcination time is 2-8h, the secondary calcination temperature is 700-900 ℃, and the calcination time is 10-20 h.

Preferably, the molar ratio of the lithium source to the positive electrode material precursor is (1.02-1.05):1, preferably, the lithium source is a lithium salt, preferably, the lithium salt is lithium hydroxide;

the method also comprises the step of crushing the material after the primary calcination between the primary calcination and the secondary calcination.

The invention also provides a battery anode, which comprises the anode material or the anode material prepared by the preparation method.

The invention also provides a lithium ion battery, and the positive electrode of the lithium ion battery is the battery positive electrode.

The invention has the beneficial effects that:

1. the chemical general formula of the precursor of the cathode material provided by the invention is Mn_XFe_1-X(OH)₂Wherein X is more than 0.45 and less than 0.65. According to the invention, the precursor is adopted, hydroxyl is taken as a precursor ligand, researches show that the distribution of ferromanganese metal elements on the precursor is more uniform, the ferromanganese lithium anode material prepared by using the precursor has excellent rate performance, and meanwhile, the invention combines the ferromanganese metal elements and the ferromanganese metal elements, and the nickel-free lithium anode material can effectively solve the problems of electrochemical performance degradation and safety caused by lithium-nickel mixed discharge of the traditional anode material, reduces the manufacturing and production costs of the precursor and the anode material, and is low in price of the used raw materials and environment-friendly.

2. At present, the preparation of ferromanganese precursor by a coprecipitation method is not reported, and the preparation method of the anode material precursor provided by the invention is based on two low-cost and environment-friendly metal elements of manganese and iron and adopts a simple coprecipitation methodWill be provided withThe manganese and the iron are difficult to sink togetherThe precipitated metal elements are precipitated together, so that the production process is simplified, the production cost is saved, the distribution of the two metal elements of ferromanganese in the precursor prepared by the method (preparing the ferromanganese acetate precursor by a dry method) is more uniform in the bulk phase, the improvement of the comprehensive performance of the anode material can be realized, the gas production and safety problems caused by the mixed discharge of lithium and nickel can be effectively avoided by combining the two metal elements of ferromanganese, the use of radioactive elements is reduced, the production and manufacturing cost is lowered, and the pressure of environmental protection is reduced.

The precursor prepared by the method provided by the invention has good sphericity, the distribution of ferromanganese metal elements on the precursor is more uniform, and the reversible capacity of the precursor is 105-130 mAh/g.

In addition, the invention adds a reducing agent in the coprecipitation reaction to prevent the system from being oxidized, and adds a complexing agent to adjust the precipitation process of the system so that the manganese and the iron can be uniformly coprecipitated at the same speed.

3. The cathode material provided by the invention has a chemical general formula of Li (Li)_0.02Mn_XFe_0.98-X)O₂Wherein X is more than 0.44 and less than 0.64, the precursor is prepared by two-stage sintering, so that the raw material cost in the preparation process can be effectively reduced, and the market competitiveness of the anode material is improved.

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.

The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.

Example 1

The embodiment provides a preparation method of a precursor of a positive electrode material, which comprises the following steps:

1) respectively preparing a manganese sulfate solution, a ferrous sulfate solution and a sodium hydroxide solution, wherein the molar concentration ratio of the manganese sulfate solution to the ferrous sulfate solution is 0.50:0.50, and the sum of the molar concentrations of the manganese sulfate solution and the ferrous sulfate solution is 1 mol/L; the concentration of the sodium hydroxide solution is 2 mol/L;

2) adding 2L of water into a reaction kettle, then adding 3mL of hydrazine hydrate into the water to prevent the system from being oxidized, and taking 30mL of ammonia water with the mass concentration of 25% as a complexing agent, and preparing to obtain a base solution containing a reducing agent and the complexing agent; then adding a manganese sulfate solution and a ferrous sulfate solution into the base solution at a flow rate of 100ml/h and simultaneously adding a sodium hydroxide solution to carry out coprecipitation reaction, wherein the pH value of the reaction solution is controlled to be 10.5 in the reaction process, the reaction temperature is 40 ℃, the continuous reaction time is 20h, the stirring speed is 800rpm, and the molar ratio of manganese sulfate to ferrous sulfate in the reaction solution is 0.50:0.50, filtering the reaction solution after the reaction is finished to obtain a solid reaction product, then cleaning the solid reaction product for 3 times by using ultrapure water, and drying at 120 ℃ for 18 hours after cleaning to obtain the anode material precursor, wherein the chemical general formula of the anode material precursor is Mn_0.5Fe_0.5(OH)₂The average particle size was 3.5. mu.m.

The embodiment also provides a preparation method of the cathode material, which comprises the following steps:

mixing 10g of the positive electrode material precursor prepared by the method with lithium hydroxide (the molar ratio of the positive electrode material precursor to the lithium hydroxide is 1:1.02), calcining at 550 ℃ in an air atmosphere for 5 hours, crushing, and then carrying out secondary calcination treatment at 750 ℃ for 15 hours to obtain the positive electrode material, wherein the chemical general formula of the positive electrode material is Li (Li)_0.02Mn_0.49Fe_0.49)O₂The cathode material is of a laminated structure.

Example 2

The embodiment provides a preparation method of a precursor of a positive electrode material, which comprises the following steps:

1) respectively preparing a manganese sulfate solution, a ferrous sulfate solution and a sodium hydroxide solution, wherein the molar concentration ratio of the manganese sulfate solution to the ferrous sulfate solution is 0.55:0.45, and the sum of the molar concentrations of the manganese sulfate solution and the ferrous sulfate solution is 1.5 mol/L; the concentration of the sodium hydroxide solution is 1.5 mol/L;

2) adding 2L of water into a reaction kettle, then adding 4mL of hydrazine hydrate into the water to prevent the system from being oxidized, and 35mL of ammonia water with the mass concentration of 25% as a complexing agent, and preparing to obtain a base solution containing a reducing agent and the complexing agent; then adding a manganese sulfate solution and a ferrous sulfate solution into the base solution at a flow rate of 150ml/h and simultaneously adding a sodium hydroxide solution for coprecipitation reaction, controlling the pH value of the reaction solution to be 10.0 in the reaction process, controlling the reaction temperature to be 45 ℃, keeping the reaction time to be 25h, controlling the stirring rate to be 900rpm, controlling the molar ratio of manganese sulfate to ferrous sulfate in the reaction solution to be 0.55:0.45, filtering the reaction solution after the reaction is finished to obtain a solid reaction product, cleaning the solid reaction product for 3 times by using ultrapure water, and drying at 120 ℃ for 18h after cleaning to obtain the anode material precursor, wherein the chemical general formula of the anode material precursor is Mn_0.55Fe_0.45(OH)₂The average particle size was 4 μm.

The embodiment also provides a preparation method of the cathode material, which comprises the following steps:

mixing 10g of the positive electrode material precursor prepared by the method with lithium hydroxide (the molar ratio of the positive electrode material precursor to the lithium hydroxide is 1:1.02), calcining for 4 hours at 600 ℃ in an air atmosphere, crushing, and then carrying out secondary calcination treatment at 750 ℃ for 12 hours to obtain the positive electrode material, wherein the chemical general formula of the positive electrode material is Li (Li)_0.02Mn_0.54Fe_0.44)O₂The cathode material is of a laminated structure.

Example 3

The embodiment provides a preparation method of a precursor of a positive electrode material, which comprises the following steps:

1) respectively preparing a manganese sulfate solution, a ferrous sulfate solution and a sodium hydroxide solution, wherein the molar concentration ratio of the manganese sulfate solution to the ferrous sulfate solution is 0.60:0.40, and the sum of the molar concentrations of the manganese sulfate solution and the ferrous sulfate solution is 2 mol/L; the concentration of the sodium hydroxide solution is 2 mol/L;

2) adding 2L of water into a reaction kettle, then adding 4mL of hydrazine hydrate into the water to prevent the system from being oxidized, and taking 30mL of ammonia water with the mass concentration of 25% as a complexing agent, and preparing to obtain a base solution containing a reducing agent and the complexing agent; then adding a manganese sulfate solution and a ferrous sulfate solution into the base solution at a flow rate of 100ml/h and simultaneously adding a sodium hydroxide solution for coprecipitation reaction, controlling the pH value of the reaction solution to be 9.8 in the reaction process, controlling the reaction temperature to be 50 ℃, keeping the reaction time to be 25h, stirring at a speed of 900rpm, controlling the molar ratio of manganese sulfate to ferrous sulfate in the reaction solution to be 0.60:0.40, filtering the reaction solution after the reaction is finished to obtain a solid reaction product, cleaning the solid reaction product for 3 times by using ultrapure water, and drying at 120 ℃ for 18h after cleaning to obtain the anode material precursor, wherein the chemical general formula of the anode material precursor is Mn_0.6Fe_0.4(OH)₂The average particle size was 4.20. mu.m.

The embodiment also provides a preparation method of the cathode material, which comprises the following steps:

mixing 10g of the positive electrode material precursor prepared by the method with lithium hydroxide (the molar ratio of the positive electrode material precursor to the lithium hydroxide is 1:1.02), calcining at 550 ℃ in an air atmosphere for 5 hours, crushing, and then carrying out secondary calcination treatment at 750 ℃ for 15 hours to obtain the positive electrode material, wherein the chemical general formula of the positive electrode material is Li (Li)_0.02Mn_0.59Fe_0.39)O₂The cathode material is of a laminated structure.

Example 4

The embodiment provides a preparation method of a precursor of a positive electrode material, which comprises the following steps:

1) respectively preparing a manganese sulfate solution, a ferrous sulfate solution and a potassium hydroxide solution, wherein the molar concentration ratio of the manganese sulfate solution to the ferrous sulfate solution is 0.65:0.35, and the sum of the molar concentrations of the manganese sulfate solution and the ferrous sulfate solution is 1.5 mol/L; the concentration of the potassium hydroxide solution is 3 mol/L;

2) adding 2L of water into a reaction kettle, then adding 10mL of hydrazine hydrate into the water to prevent the system from being oxidized, and taking 50mL of ammonia water with the mass concentration of 25% as a complexing agent, and preparing to obtain a base solution containing a reducing agent and the complexing agent; then adding a manganese sulfate solution and a ferrous sulfate solution into the base solution at a flow rate of 200ml/h and simultaneously adding a potassium hydroxide solution to carry out coprecipitation reaction, controlling the pH value of the reaction solution to be 9.5 in the reaction process, controlling the reaction temperature to be 50 ℃, keeping the reaction time to be 20h, stirring at a speed of 1000rpm, controlling the molar ratio of manganese sulfate to ferrous sulfate in the reaction solution to be 0.65:0.35, filtering the reaction solution after the reaction is finished to obtain a solid reaction product, cleaning the solid reaction product for 5 times by using ultrapure water, and drying at 120 ℃ for 18h after cleaning to obtain the anode material precursor, wherein the chemical general formula of the anode material precursor is Mn_0.65Fe_0.35(OH)₂The average particle size was 5.0. mu.m.

The embodiment also provides a preparation method of the cathode material, which comprises the following steps:

mixing 10g of the positive electrode material precursor prepared by the method with lithium hydroxide (the molar ratio of the positive electrode material precursor to the lithium hydroxide is 1:1.02), calcining for 2 hours at 600 ℃ in an air atmosphere, crushing, and then carrying out secondary calcination treatment at 900 ℃ for 10 hours to obtain the positive electrode material, wherein the chemical general formula of the positive electrode material is Li (Li)_0.02Mn_0.64Fe_0.34)O₂The cathode material is of a laminated structure.

Example 5

The embodiment provides a preparation method of a precursor of a positive electrode material, which comprises the following steps:

1) respectively preparing a manganese acetate solution, a ferrous acetate solution and a sodium hydroxide solution, wherein the molar concentration ratio of the manganese acetate solution to the ferrous acetate solution is 0.50:0.50, and the sum of the molar concentrations of the manganese acetate solution and the ferrous acetate solution is 1 mol/L; the concentration of the sodium hydroxide solution is 2 mol/L;

2) adding 2L of water into a reaction kettle, then adding 3mL of hydrazine hydrate into the water to prevent the system from being oxidized, and taking 30mL of ammonia water with the mass concentration of 25% as a complexing agent, and preparing to obtain a base solution containing a reducing agent and the complexing agent; then respectively adding a manganese acetate solution and a ferrous acetate solution into the base solution at a flow rate of 100ml/h, simultaneously adding a sodium hydroxide solution to carry out coprecipitation reaction, controlling the pH value of the reaction solution to be 10.50 in the reaction process, controlling the reaction temperature to be 40 ℃, controlling the reaction duration to be 20h, controlling the stirring speed to be 800rpm, and controlling the molar ratio of manganese acetate to ferrous acetate in the reaction solution to be 1:1, filtering reaction liquid after the reaction is finished to obtain a solid reaction product, then cleaning the solid reaction product for 3 times by using ultrapure water, and drying at 120 ℃ for 18 hours after cleaning to obtain the anode material precursor, wherein the chemical general formula of the anode material precursor is Mn_0.5Fe_0.5(OH)₂The average particle size was 3.5. mu.m.

The embodiment also provides a preparation method of the cathode material, which comprises the following steps:

mixing 10g of the positive electrode material precursor prepared by the method with lithium hydroxide (the molar ratio of the positive electrode material precursor to the lithium hydroxide is 1:1.02), calcining at 550 ℃ in an air atmosphere for 5 hours, crushing, and then carrying out secondary calcination treatment at 750 ℃ for 15 hours to obtain the positive electrode material, wherein the chemical general formula of the positive electrode material is Li (Li)_0.02Mn_0.49Fe_0.49)O₂The cathode material is of a laminated structure.

Comparative example 1

The comparative example provides a preparation method of a precursor of a positive electrode material, comprising the following steps:

1) adding 1mol of manganese acetate and 1mol of ferrous acetate into a mortar, mixing and grinding for 30min, then adding ammonium oxalate (5mol), mixing and grinding for 30min, wherein the protection of inert gas is adopted in the grinding process, the raw material is changed into slurry from solid, and then is changed into paste, and finally a powdery binary precursor is obtained; the chemical general formula of the precursor of the cathode material is Mn_0.5Fe_0.5(C₂O₄)₂。

The comparative example also provides a method for preparing the cathode material, comprising the following steps:

mixing 10g of the positive electrode material precursor prepared by the method with lithium hydroxide (the molar ratio of the positive electrode material precursor to the lithium hydroxide is 1:1.02), calcining at 550 ℃ in an air atmosphere for 5 hours, crushing, and then carrying out secondary calcination treatment at 750 ℃ for 15 hours to obtain the positive electrode material, wherein the chemical general formula of the positive electrode material is Li (Li)_0.02Mn_0.49Fe_0.49)O₂The cathode material is of a laminated structure.

Test example

The positive electrode materials prepared in the above examples and comparative examples were prepared into lithium ion half cells, and charge and discharge tests were performed, specifically as follows:

the positive electrode materials prepared in examples and comparative examples were mixed with SP (carbon black conductive agent), CNT (carbon nanotube), PVDF (polyvinylidene fluoride) at a ratio of 80: 5: 5: 10, then NMP (N-methyl pyrrolidone) is used as a solvent for pulping and stirring, the obtained mixture is uniformly mixed and then coated on an aluminum foil, the obtained mixture is dried to obtain a positive electrode, EC (ethylene carbonate) is used as an electrolyte, a lithium sheet is used as a negative electrode, a lithium ion half battery is assembled, and the assembled battery is tested for the specific capacity of the battery under the 1C multiplying power at the temperature of 25 ℃ and the voltage of 2.5-4.5V.

The test results are shown in table 1.

TABLE 1 Performance of the cell

	Specific capacity (mAh/g)
		Example 1	115
Example 2	118
		Example 3	120
Example 4	126
		Example 5	105
Comparative example 1	90

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.