阅读说明：本技术 一种可用于锂电池的杨梅状富锂正极材料的制备方法 (Preparation method of waxberry-shaped lithium-rich cathode material for lithium battery ) 是由 彭栋梁 谢清水 王来森 张晨莺 麻亚挺 郑鸿飞 于 2020-07-01 设计创作，主要内容包括：一种可用于锂电池的杨梅状富锂正极材料的制备方法,涉及锂电池技术领域。提供工艺简单、原料成本低和环境友好,具有良好的结构稳定性和容量与电压稳定性的一种可用于锂电池的杨梅状富锂正极材料的制备方法。包括以下步骤：1)将过渡金属盐中的至少一种溶于去离子水中,配制成混合盐溶液A；2)将碳酸盐溶于去离子水中,配制成溶液B；3)在连续搅拌反应釜中加入酒石酸盐溶液；4)将溶液A和溶液B泵入反应釜中反应；5)反应结束后收集产物,过滤、洗涤、真空干燥后制得碳酸盐前驱体；6)将干燥后的碳酸盐前驱体置于马弗炉中煅烧,制得到氧化物前驱体；7)将氧化物前驱体与锂盐混合,热处理后制备出杨梅状富锂正极材料。(A preparation method of a waxberry-shaped lithium-rich cathode material for a lithium battery relates to the technical field of lithium batteries. The preparation method of the waxberry-shaped lithium-rich cathode material for the lithium battery is simple in process, low in raw material cost, environment-friendly, and good in structural stability, capacity and voltage stability. The method comprises the following steps: 1) dissolving at least one of transition metal salts in deionized water to prepare a mixed salt solution A; 2) dissolving carbonate in deionized water to prepare a solution B; 3) adding a tartrate solution into a continuous stirring reaction kettle; 4) pumping the solution A and the solution B into a reaction kettle for reaction; 5) collecting the product after the reaction is finished, filtering, washing and drying in vacuum to obtain a carbonate precursor; 6) placing the dried carbonate precursor into a muffle furnace for calcining to obtain an oxide precursor; 7) and mixing the oxide precursor with a lithium salt, and performing heat treatment to prepare the waxberry-shaped lithium-rich cathode material.)

1. A preparation method of a waxberry-shaped lithium-rich cathode material for a lithium battery is characterized by comprising the following steps of:

1) dissolving at least one of transition metal salts in deionized water to prepare a mixed salt solution A;

2) dissolving carbonate in deionized water to prepare a solution B;

3) adding a tartrate solution into a continuous stirring reaction kettle;

4) pumping the mixed salt solution A and the solution B into a reaction kettle for reaction;

5) collecting the product after the reaction is finished, filtering, washing and drying in vacuum to obtain a carbonate precursor;

6) placing the dried carbonate precursor into a muffle furnace for calcining to obtain an oxide precursor;

7) and mixing the oxide precursor with a lithium salt, and performing heat treatment to prepare the waxberry-shaped lithium-rich cathode material.

2. The method according to claim 1, wherein in step 1), the transition metal salt is selected from manganese salt, nickel salt, cobalt salt or other transition metal salts; the manganese salt can be at least one selected from manganese acetate, manganese nitrate, manganese sulfate and manganese chloride; the nickel salt can be selected from at least one of nickel acetate, nickel nitrate, nickel sulfate and nickel chloride; the cobalt salt can be at least one selected from cobalt acetate, cobalt sulfate, cobalt nitrate and cobalt chloride.

3. The method according to claim 2, wherein in the step 1), the molar ratio of the manganese salt, the nickel salt and the cobalt salt is (2-4): 0-1); the molar concentration of the mixed salt solution A is 0.1-4 mol/L.

4. The method as claimed in claim 1, wherein in step 2), the carbonate is selected from potassium carbonate, sodium carbonate; the amount of carbonate is 1-1.5 times of that of the transition metal salt, and the molar concentration of the solution B is 0.1-6 mol/L.

5. The method according to claim 1, wherein in the step 3), the tartrate solution has a molar concentration of 0.01 to 0.1 mol/L.

6. The method according to claim 1, wherein in step 4), the mixed salt solution A and the solution B are dropped into the reaction kettle at the same pumping speed; when the mixed salt solution A and the solution B are dripped into the reaction kettle, the flow rate of the peristaltic pump is controlled to be 0.1-1 mL/min, the reaction temperature is 40-80 ℃, the stirring speed is 300-600rpm, and inert gas is introduced for protection.

7. The method according to claim 1, wherein in step 6), the temperature of the calcination is 350-550 ℃, the calcination time is 2-6 h, and the temperature increase rate is 1-10 ℃/min.

8. The method according to claim 1, wherein in step 7), the lithium salt is at least one selected from the group consisting of lithium acetate, lithium nitrate, lithium sulfate, lithium fluoride, lithium hydroxide, and lithium carbonate.

9. The method according to claim 1, wherein in step 7), the molar ratio of transition metal atoms in the oxide precursor to lithium atoms in the lithium salt is 1: 1-1.5.

10. The method according to claim 1, wherein in step 7), the heat treatment temperature is 750-950 ℃, the heat treatment time is 8-18 h, and the temperature rise rate is 1-10 ℃/min.

Technical Field

The invention relates to the technical field of lithium batteries, in particular to a preparation method of a waxberry-shaped lithium-rich cathode material.

Background

Lithium ion batteries have been developed since the 20 th century and the 90 th era because of their advantages of good safety, high voltage, long life, and little pollution, and are now widely used in various fields. However, increasing energy storage requirements place higher demands on lithium ion batteries, and the development of high energy density and low cost lithium ion batteries is imminent (Zhang et al, advanced materials, 30(29), 1801751). The anode materials such as layered lithium cobaltate, spinel lithium manganate and olivine lithium iron phosphate have been widely researched, and the actual specific discharge capacities thereof have gradually approached their respective theoretical limit values, and still cannot meet the requirements of people in terms of energy density. Therefore, the development of new high-capacity cathode materials is a key point for further improving the energy density of lithium ion batteries.

The lithium-rich manganese-based positive electrode material has the advantages of high specific capacity (more than 250mAh/g), low cost, environmental friendliness and the like, and is a research hotspot in the field of chemical power sources at present. However, the rapid capacity and voltage decay caused by the structural instability of lithium-rich cathode Materials during cycling limits their commercial applications (zheng et al, Advanced Energy Materials, 2017, 7(6), 1601284). In recent years, in order to improve the electrochemical performance of lithium-rich cathode materials, researchers have made great research progress by adopting strategies such as surface coating, doping, microstructure regulation and the like. However, the problems of complicated preparation process, high cost, difficult batch production and the like of the lithium-rich cathode material still need to be further researched and solved.

Therefore, it is a very important research topic to develop an industrial preparation method capable of improving the cycle and voltage stability of the lithium-rich cathode material and reducing the production cost thereof.

Disclosure of Invention

The invention aims to provide a preparation method of a waxberry-shaped lithium-rich cathode material which has the advantages of simple process, low raw material cost, environmental friendliness, good structural stability, capacity and voltage stability and can be used for a lithium battery.

The invention comprises the following steps:

1) dissolving at least one of transition metal salts in deionized water to prepare a mixed salt solution A;

2) dissolving carbonate in deionized water to prepare a solution B;

3) adding a tartrate solution into a continuous stirring reaction kettle;

4) pumping the solution A and the solution B into a reaction kettle for reaction;

5) collecting the product after the reaction is finished, filtering, washing and drying in vacuum to obtain a carbonate precursor;

6) placing the dried carbonate precursor into a muffle furnace for calcining to obtain an oxide precursor;

7) and mixing the oxide precursor with a lithium salt, and performing heat treatment to prepare the waxberry-shaped lithium-rich cathode material.

In step 1), the transition metal salt can be selected from manganese salt, nickel salt, cobalt salt or other transition metal salts; the manganese salt can be at least one selected from manganese acetate, manganese nitrate, manganese sulfate, manganese chloride and the like; the nickel salt can be selected from at least one of nickel acetate, nickel nitrate, nickel sulfate, nickel chloride and the like; the cobalt salt can be at least one selected from cobalt acetate, cobalt sulfate, cobalt nitrate, cobalt chloride and the like; the molar ratio of the manganese salt, the nickel salt and the cobalt salt can be (2-4): 0-1); the molar concentration of the mixed salt solution A is 0.1-4 mol/L.

In the step 2), the carbonate can be potassium carbonate, sodium carbonate and other carbonates; the amount of carbonate is 1-1.5 times of that of the transition metal salt, and the molar concentration of the solution B is 0.1-6 mol/L.

In the step 3), the molar concentration of the tartrate solution is 0.01-0.1 mol/L.

In the step 4), the mixed salt solutions A and B are dropped into the reaction kettle at the same pump speed; when the solution A and the solution B are dripped into the reaction kettle, the flow rate of the peristaltic pump is controlled to be 0.1-1 mL/min, the reaction temperature is 40-80 ℃, the stirring speed is 300-600rpm, and inert gas is introduced for protection.

In the step 6), the calcining temperature can be 350-550 ℃, the calcining time can be 2-6 h, and the heating rate can be 1-10 ℃/min.

In step 7), the lithium salt may be selected from at least one of lithium acetate, lithium nitrate, lithium sulfate, lithium fluoride, lithium hydroxide, and lithium carbonate; the molar ratio of transition metal atoms in the oxide precursor to lithium in the lithium salt can be 1: 1-1.5; the temperature of the heat treatment can be 750-950 ℃, the time of the heat treatment can be 8-18 h, and the heating rate can be 1-10 ℃/min.

Compared with the existing lithium-rich layered cathode material, the lithium-rich layered cathode material has the following outstanding advantages:

the preparation of the carbonate precursor adopts a coprecipitation method at a lower temperature, water is used as a solvent, and only a small amount of tartrate is added as a complexing agent, so that the method is green and environment-friendly. The prepared precursor has uniform grain diameter, uniform element distribution and better consistency. The lithium-rich cathode material with excellent comprehensive performance is prepared by direct lithium mixing and calcining, modification measures such as doping and coating are not needed, the cost is low, and the industrial production is easy to realize. The lithium-rich cathode material prepared by the invention has a core-shell structure with a spherical core inside and a radial rod-shaped shell outside. The unique waxberry-shaped structure has good structural stability, capacity and voltage stability, and the unique morphology and exposed crystal faces enable the material to have excellent cycle and voltage stability and rate capability, so that the possibility is provided for the development of high-energy-density and low-cost lithium batteries. The preparation method has the advantages of simple process, low raw material cost, environmental friendliness and the like, and is favorable for realizing large-scale production.

Drawings

FIG. 1 shows Li obtained in example 1_1.2Mn_0.54Co_0.13Ni_0.13O₂XRD pattern of lithium-rich cathode material. In fig. 1, the abscissa is the 2 θ diffraction angle, and the ordinate is the diffraction intensity.

FIG. 2 shows Li obtained in example 1_1.2Mn_0.54Co_0.13Ni_0.13O₂Scanning electron microscopy of lithium-rich cathode materials. In FIG. 2, a is 2 μm on a scale and b is 1 μm on a scale.

FIG. 3 shows Li obtained in example 1_1.2Mn_0.54Co_0.13Ni_0.13O₂Transmission electron microscope image after FIB slicing of lithium-rich cathode material.

FIG. 4 shows Li obtained in example 1_1.2Mn_0.54Co_0.13Ni_0.13O₂Rate performance graph of lithium-rich cathode material.

FIG. 5 shows Li obtained in example 1_1.2Mn_0.54Co_0.13Ni_0.13O₂Electrochemical performance of the lithium-rich cathode material at a current density of 1C (250 mA/g).

Detailed Description

The invention will be described and illustrated in more detail with reference to specific examples.

The embodiment of the invention comprises the following steps:

1) dissolving at least one of transition metal salts in deionized water to prepare a mixed salt solution A; the transition metal salt can be selected from manganese salt, nickel salt, cobalt salt or other transition metal salts; the manganese salt can be at least one selected from manganese acetate, manganese nitrate, manganese sulfate, manganese chloride and the like; the nickel salt can be selected from at least one of nickel acetate, nickel nitrate, nickel sulfate, nickel chloride and the like; the cobalt salt can be at least one selected from cobalt acetate, cobalt sulfate, cobalt nitrate, cobalt chloride and the like; the molar ratio of the manganese salt, the nickel salt and the cobalt salt can be (2-4): 0-1); the molar concentration of the mixed salt solution A is 0.1-4 mol/L.

2) Dissolving carbonate in deionized water to prepare a solution B; the carbonate can be selected from carbonate such as potassium carbonate and sodium carbonate; the amount of carbonate is 1-1.5 times of that of the transition metal salt, and the molar concentration of the solution B is 0.1-6 mol/L.

3) Adding a tartrate solution into a continuous stirring reaction kettle; the molar concentration of the tartrate solution is 0.01-0.1 mol/L.

4) Pumping the mixed salt solution A and the solution B into a reaction kettle for reaction; the mixed salt solution A and the solution B are dropped into the reaction kettle at the same pump speed; when the mixed salt solution A and the solution B are dripped into the reaction kettle, the flow rate of a peristaltic pump is controlled to be 0.1-1 mL/min, the reaction temperature is 40-80 ℃, the stirring speed is 300-600rpm, and inert gas is introduced for protection.

5) Collecting the product after the reaction is finished, filtering, washing and drying in vacuum to obtain a carbonate precursor;

6) placing the dried carbonate precursor into a muffle furnace for calcining to obtain an oxide precursor; the calcining temperature can be 350-550 ℃, the calcining time can be 2-6 h, and the heating rate can be 1-10 ℃/min.

7) And mixing the oxide precursor with a lithium salt, and performing heat treatment to prepare the waxberry-shaped lithium-rich cathode material. The lithium salt can be selected from at least one of lithium acetate, lithium nitrate, lithium sulfate, lithium fluoride, lithium hydroxide and lithium carbonate; the molar ratio of transition metal atoms in the oxide precursor to lithium in the lithium salt can be 1: 1-1.5; the temperature of the heat treatment can be 750-950 ℃, the time of the heat treatment can be 8-18 h, and the heating rate can be 1-10 ℃/min.

Specific examples are given below.