阅读说明：本技术 一种锂离子电池负极材料及其制备方法 (Lithium ion battery cathode material and preparation method thereof ) 是由 杨书廷 贾伟晓 郑延辉 张芬丽 于 2021-09-18 设计创作，主要内容包括：本发明公开了一种锂离子电池负极材料的制备方法,包括以下步骤：步骤一,在碳源分散液中加入锡盐、钒盐,水浴条件下混匀；干燥成固体粉末；其中钒、锡摩尔比为钒：锡=1:9-9:1,碳源加入量为:每摩尔钒加碳源100g；步骤二,所得固体粉末在非氧化性气体保护下550-700℃热处理2-4小时,得到碳包覆钒锡氧化物；步骤三,将所得碳包覆钒锡氧化物与碳材料混合得锂离子电池负极材料,其中碳包覆钒锡氧化物质量百分比为5-10%。本发明还提供了上述方法制备的锂离子电池负极材料。本发明所制备的锂离子电池负极材料中将锡和钒氧化物的联合使用,提高了锂离子电池负极材料的容量、首次充放电效率和循环性能。(The invention discloses a preparation method of a lithium ion battery cathode material, which comprises the following steps: adding tin salt and vanadium salt into a carbon source dispersion liquid, and uniformly mixing under a water bath condition; drying into solid powder; wherein the molar ratio of vanadium to tin is vanadium: tin =1:9-9:1, the addition of carbon source is 100g per mol of vanadium; step two, carrying out heat treatment on the obtained solid powder for 2-4 hours at the temperature of 550-700 ℃ under the protection of non-oxidizing gas to obtain carbon-coated vanadium-tin oxide; and step three, mixing the obtained carbon-coated vanadium-tin oxide with a carbon material to obtain the lithium ion battery negative electrode material, wherein the mass percentage of the carbon-coated vanadium-tin oxide is 5-10%. The invention also provides the lithium ion battery cathode material prepared by the method. The prepared lithium ion battery cathode material combines tin and vanadium oxide, and improves the capacity, the first charge-discharge efficiency and the cycle performance of the lithium ion battery cathode material.)

1. The preparation method of the lithium ion battery negative electrode material is characterized by comprising the following steps of:

adding tin salt and vanadium salt into a carbon source dispersion liquid, and uniformly mixing under a water bath condition; drying into solid powder; wherein the molar ratio of vanadium to tin is vanadium: tin =1:9-9:1, the addition of carbon source is 100g per mol of vanadium;

step two, carrying out heat treatment on the obtained solid powder at the temperature of 550-700 ℃ for 2-4 hours under the protection of non-oxidizing gas to obtain carbon-coated vanadium-tin oxide;

and step three, uniformly mixing the obtained carbon-coated vanadium-tin oxide and a carbon material to obtain the lithium ion battery negative electrode material, wherein the mass percentage of the carbon-coated vanadium-tin oxide is 5-10%.

2. The method for preparing the negative electrode material of the lithium ion battery according to claim 1, wherein the carbon source is at least one of glucose, sucrose, starch and cellulose.

3. The method for preparing the negative electrode material of the lithium ion battery according to claim 1, wherein the tin salt is stannous dichloride, stannic chloride, stannous nitrate or stannous sulfate, and the concentration of the tin salt in the first step is 0.04-0.9 mol/L.

4. The method for preparing the negative electrode material of the lithium ion battery according to claim 1, wherein the vanadium salt is ammonium metavanadate or vanadyl oxalate, and the concentration of the vanadium salt in the first step is 0.04-0.36 mol/L.

5. The method of preparing the negative electrode material for a lithium ion battery of claim 1, wherein the non-oxidizing gas is at least one of nitrogen and argon.

6. The method for preparing the negative electrode material of the lithium ion battery according to claim 1, wherein the carbon material in the third step is at least one of artificial graphite, natural graphite and mesocarbon microbeads.

7. The method for preparing the negative electrode material of the lithium ion battery as claimed in claim 1, wherein the drying in the step one is spray drying, the temperature of a gas inlet of the spray drying is 150-200 ℃, and the temperature of a gas outlet of the spray drying is 60-80 ℃.

8. The method for preparing the negative electrode material of the lithium ion battery according to claim 1, wherein the water bath temperature in the first step is 60-80 ℃.

9. A lithium ion battery negative electrode material, characterized in that it is prepared by the method of any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery cathode material and a preparation method thereof.

Background

In recent years, with the rapid development of 3C digital products, energy storage, communication and new energy automobile fields, people have more and more stringent requirements on the performance of lithium ion batteries. The negative electrode material of the lithium ion battery has a large influence on the performance of the battery, the graphite negative electrode and the silicon electrode have certain limits on the application range due to the defects of the graphite negative electrode and the silicon electrode, and the capacity and the cycle performance of the graphite negative electrode and the silicon electrode are poor.

Disclosure of Invention

The purpose of the invention is as follows: provides a high-capacity lithium ion battery cathode material with good cycle performance and a preparation method thereof.

The technical scheme of the invention is as follows:

a preparation method of a lithium ion battery negative electrode material comprises the following steps:

adding tin salt and vanadium salt into a carbon source dispersion liquid, and uniformly mixing under a water bath condition; drying into solid powder; wherein the molar ratio of vanadium to tin is vanadium: tin =1:9-9:1, the addition of carbon source is 100g per mol of vanadium;

step two, carrying out heat treatment on the obtained solid powder at the temperature of 550-700 ℃ for 2-4 hours under the protection of non-oxidizing gas to obtain carbon-coated vanadium-tin oxide;

and step three, uniformly mixing the obtained carbon-coated vanadium-tin oxide and a carbon material to obtain the lithium ion battery negative electrode material, wherein the mass percentage of the carbon-coated vanadium-tin oxide is 5-10%.

Preferably, the carbon source is at least one of glucose, sucrose, starch and cellulose.

Preferably, the tin salt is stannous chloride, stannic chloride, stannous nitrate or stannous sulfate, and the concentration of the tin salt in the first step is 0.04-0.9 mol/L.

Preferably, the vanadium salt is ammonium metavanadate or vanadyl oxalate, and the concentration of the vanadium salt in the first step is 0.04-0.36 mol/L.

Preferably, the non-oxidizing gas is at least one of nitrogen and argon.

Preferably, the carbon material in step three is at least one of artificial graphite, natural graphite and mesocarbon microbeads.

Preferably, the drying in the first step is spray drying, the temperature of a gas inlet of the spray drying is 150-200 ℃, and the temperature of a gas outlet of the spray drying is 60-80 ℃.

Preferably, the temperature of the water bath in the first step is 60-80 ℃.

The invention also provides the lithium ion battery cathode material prepared by the method.

The invention has the beneficial effects that:

according to the preparation method of the lithium ion battery cathode material, the tin salt and the vanadium salt added in the step one are partially hydrolyzed into basic salt under the water bath condition, and the tin and the vanadium are partially oxidized in the drying process; in the heat treatment process of the second step, the basic salt is decomposed into oxides, the vanadium oxide is crystallized into layers at high temperature, the tin oxide is crystallized into a rod shape, the tin oxide with the rod-shaped structure is inserted between the layers of the vanadium oxide, the layer-shaped structure of the vanadium oxide is supported, and the collapse of the layer-shaped structure can be effectively prevented; meanwhile, the vanadium oxide layered structure can provide a buffering place for the expansion and contraction of the tin oxide, and the tin and the vanadium are jointly used to play a synergistic role, so that the cycle performance of the lithium ion battery cathode material is improved. Secondly, high-valence vanadium is converted into low-valence vanadium with higher capacity by the carbon decomposed at high temperature in the step II, so that the negative electrode material has higher capacity; meanwhile, carbon decomposed at high temperature is coated outside the vanadium and tin oxides, so that the conductivity of the lithium ion battery cathode material is improved. According to the preparation method of the lithium ion battery cathode material, the tin and vanadium compounds are used in a combined manner, and the prepared vanadium-tin oxide is coated with carbon and then mixed with the carbon material to prepare the lithium ion battery cathode material, so that the capacity, the first charge-discharge efficiency and the cycle performance of the lithium ion battery cathode material are improved.

Detailed Description

The present invention will be described in detail with reference to examples.

Example 1

1. The method for preparing the lithium ion battery cathode material comprises the following steps:

weighing 6g of glucose, dissolving the glucose in 200ml of deionized water, adding tin dichloride and ammonium metavanadate to enable the concentration of the tin dichloride to be 0.2mol/L and the concentration of the ammonium metavanadate to be 0.3mol/L, placing the solution on a water bath magnetic stirrer, setting the water bath temperature to be 70 ℃, and stirring for 2 hours. Spray drying the obtained solution to obtain solid powder; wherein the temperature of the air inlet of the spray drying is 150 ℃, and the temperature of the material outlet is 60 ℃.

And step two, carrying out heat treatment on the obtained solid powder for 3 hours at the temperature of 600 ℃ under the protection of nitrogen, naturally cooling to room temperature, and sieving by using a 250-mesh sieve to obtain the carbon-coated vanadium-tin oxide.

And step three, uniformly mixing the obtained carbon-coated vanadium-tin oxide and natural graphite in a mass ratio of 5:95 to obtain the lithium ion battery cathode material.

2. And (3) testing electrical properties:

uniformly mixing the prepared lithium ion battery negative electrode material with polyacrylic acid and superconducting carbon according to the mass ratio of 8:1:1, adding deionized water, stirring until the material becomes a mixed slurry with fluidity, coating the mixed slurry on a copper foil, drying and cutting the copper foil to obtain a negative electrode piece. Putting the pole piece into a glove box, taking a metal lithium piece as a counter electrode, adopting a polypropylene diaphragm and 1mol/L LiPF₆And the solution of/EC + DEC + EMC is electrolyte, wherein EC is ethylene carbonate, DEC is diethyl carbonate, EMC is ethyl methyl carbonate, the volume ratio of EC to DEC to EMC is 1:1:1, and the solution is assembled into the CR2032 type button cell in a glove box filled with dry argon.

And (3) testing performance: and (3) carrying out electrical property test on the prepared button cell on a blue light test system, wherein the test temperature is 25 +/-2 ℃, and the method comprises the following steps:

discharging the button cell battery at 0.1C to 0.005V, and standing for 1 min; discharging to 0.005V at 0.05C, and standing for 1 min; discharging to 0.005V at 0.02C, and standing for 1 min; 0.1C to 3.0V; the first charge specific capacity of the battery is 406.41mAh/g, and the first charge-discharge efficiency is 90.42%. After 100 cycles of the same charge and discharge method, the capacity retention ratio was found to be 81.76%. The test results are shown in Table 1.

Example 2

1. The method for preparing the lithium ion battery cathode material comprises the following steps:

step one, weighing 1g of starch, dissolving the starch in 100ml of deionized water, then adding tin tetrachloride and vanadyl oxalate pentahydrate to enable the concentration of the tin tetrachloride to be 0.9mol/L and the concentration of the vanadyl oxalate to be 0.1mol/L, placing the solution on a water bath magnetic stirrer, setting the water bath temperature to be 60 ℃, and stirring for 2 hours. Spray drying the obtained solution to obtain solid powder; wherein the temperature of the air inlet of the spray drying is 200 ℃, and the temperature of the material outlet is 80 ℃.

And step two, carrying out heat treatment on the obtained solid powder for 2 hours at 550 ℃ under the protection of argon, naturally cooling to room temperature, and sieving with a 250-mesh sieve to obtain the carbon-coated vanadium-tin oxide.

And step three, uniformly mixing the obtained carbon-coated vanadium tin oxide and the mesocarbon microbeads in a mass ratio of 5:95 to obtain the lithium ion battery cathode material.

2. And (3) testing electrical properties:

the electrical properties were measured in the same manner as in example 1, and the results are shown in Table 1.

Example 3

1. The method for preparing the lithium ion battery cathode material comprises the following steps:

weighing 9g of sucrose, dissolving the sucrose in 250ml of deionized water, adding 20 parts of stannous nitrate hydrate and ammonium metavanadate to ensure that the concentration of the stannous nitrate is 0.04mol/L and the concentration of the ammonium metavanadate is 0.36mol/L, placing the solution on a water bath magnetic stirrer, setting the water bath temperature to be 80 ℃, and stirring for 2 hours. Spray drying the obtained solution to obtain solid powder; wherein the temperature of the air inlet of the spray drying is 200 ℃, and the temperature of the material outlet is 60 ℃.

And step two, carrying out heat treatment on the obtained solid powder for 4 hours at 700 ℃ under the protection of nitrogen, naturally cooling to room temperature, and sieving with a 250-mesh sieve to obtain the carbon-coated vanadium-tin oxide.

And step three, uniformly mixing the obtained carbon-coated vanadium-tin oxide and artificial graphite in a mass ratio of 10:90 to obtain the lithium ion battery negative electrode material.

2. And (3) testing electrical properties: the electrical properties were measured in the same manner as in example 1, and the results are shown in Table 1.

Example 4

1. The method for preparing the lithium ion battery cathode material comprises the following steps:

step one, weighing 1g of cellulose, dissolving the cellulose in 250ml of deionized water, adding stannous sulfate and ammonium metavanadate to ensure that the concentration of the stannous sulfate is 0.36mol/L and the concentration of the ammonium metavanadate is 0.04mol/L, placing the solution on a water bath magnetic stirrer, setting the water bath temperature to be 70 ℃, and stirring for 2 hours. Spray drying the obtained solution to obtain solid powder; wherein the temperature of the air inlet of the spray drying is 150 ℃, and the temperature of the material outlet is 60 ℃.

And step two, carrying out heat treatment on the obtained solid powder for 2 hours at the temperature of 600 ℃ under the protection of nitrogen, naturally cooling to room temperature, and sieving by using a 250-mesh sieve to obtain the carbon-coated vanadium-tin oxide.

And step three, uniformly mixing the obtained carbon-coated vanadium-tin oxide and natural graphite in a mass ratio of 5:95 to obtain the lithium ion battery cathode material.

2. And (3) testing electrical properties: the electrical properties were measured in the same manner as in example 1, and the results are shown in Table 1.

Comparative example 1

1. Preparing a tin-carbon composite negative electrode material for a lithium ion battery:

step one, weighing 6g of glucose, dissolving the glucose in 200ml of deionized water, adding tin dichloride until the concentration of the tin dichloride is 0.5mol/L, placing the solution on a water bath magnetic stirrer, setting the temperature of the water bath to be 70 ℃, and stirring for 2 hours. Spray drying the obtained solution to obtain solid powder; wherein the temperature of the air inlet of the spray drying is 150 ℃, and the temperature of the material outlet is 60 ℃.

And step two, carrying out heat treatment on the obtained solid powder for 3 hours at the temperature of 600 ℃ under the protection of nitrogen, naturally cooling to room temperature, and sieving by using a 250-mesh sieve to obtain the carbon-coated tin oxide.

And step three, mixing the obtained carbon-coated tin oxide with artificial graphite in a mass ratio of 5:95 to obtain the lithium ion battery negative electrode material.

2. And (3) testing electrical properties: the electrical properties were measured in the same manner as in example 1, and the results are shown in Table 1.

Comparative example 2

1. The method for preparing the lithium ion battery cathode material comprises the following steps:

weighing 6g of glucose, dissolving the glucose in 200ml of deionized water, adding ammonium metavanadate to enable the concentration of the ammonium metavanadate to be 0.5mol/L, placing the solution on a water bath magnetic stirrer, setting the water bath temperature to be 70 ℃, and stirring for 2 hours. Spray drying the obtained solution to obtain solid powder; wherein the temperature of the air inlet of the spray drying is 150 ℃, and the temperature of the material outlet is 60 ℃.

And step two, carrying out heat treatment on the obtained solid powder for 3 hours at the temperature of 600 ℃ under the protection of nitrogen, naturally cooling to room temperature, and sieving by using a 250-mesh sieve to obtain the carbon-coated vanadium oxide.

And step three, mixing the obtained carbon-coated vanadium oxide and artificial graphite in a mass ratio of 5:95 to obtain the lithium ion battery negative electrode material.

2. And (3) testing electrical properties: the electrical properties were measured in the same manner as in example 1, and the results are shown in Table 1.

TABLE 1

As can be seen from the results in table 1, the lithium ion battery negative electrode materials prepared by using the methods of examples 1 to 4 of the present invention have high first charge specific capacity and cycle performance, and the carbon-coated vanadium tin oxide is used as a lithium ion battery negative electrode material, and the vanadium oxide and the tin oxide have complementary advantages in the negative electrode material, so that the first charge specific capacity and the first charge efficiency can be improved. The negative electrode materials of the lithium ion battery prepared by the comparative example 1 and the comparative example 2 are poor in the first charge specific capacity and the first charge efficiency. The combined use of tin and vanadium is beneficial to improving the electrical property of the cathode material of the lithium ion battery. According to the preparation method of the lithium ion battery cathode material, tin salt and vanadium salt are partially hydrolyzed into basic salt under the water bath condition of the step I; during the drying process, vanadium and tin are respectively partially oxidized; in the heat treatment process of the second step, the tin salt and the vanadium salt are decomposed into oxides, the carbon source is decomposed into carbon at high temperature, and the carbon obtained by decomposition is used as a reducing agent to convert high-valence vanadium into low-valence vanadium with high capacity; in addition, the unoxidized decomposed carbon can also be used as a conductive agent to increase the conductivity of the negative electrode material and improve the electrical property of the negative electrode material; the carbon coated on the surface of the vanadium-tin oxide can play a role in restraining the volume expansion of the vanadium-tin oxide in the charging process, integrally improves the expansion of the negative electrode material, and obviously improves the conductivity and the cycle life of the negative electrode material as a lithium ion negative electrode material. And, during the heat treatment of the second step, the high temperature makes the vanadium oxide to be crystallized in a layered shape and the tin oxide to be crystallized in a rod shape; the tin oxide with the rod-shaped structure is inserted between the layered structures of the vanadium oxide to support the layered structures of the vanadium oxide, so that the collapse of the layered structures can be effectively prevented; meanwhile, the vanadium oxide layered structure can provide a buffering place for the expansion and contraction of the tin oxide, and the tin and the vanadium are jointly used to play a synergistic role, so that the electrochemical performance of the lithium ion battery cathode material is improved. The precursor solid particles can be obtained by spray drying, and the carbon source of the precursor solid particles can more easily enter between the precursor solid particles and inside the precursor solid particles under the high-temperature condition, so that the precursor solid particles also have the advantage in the aspect of later-stage processing performance.

It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features related to the embodiments of the present invention described above may be combined with each other as long as they do not conflict with each other. In addition, the above embodiments are only some embodiments of the present invention, not all embodiments, and all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without any creative work belong to the protection scope of the present invention. For example, for the carbon material, only the artificial graphite, the natural graphite and the mesocarbon microbeads are used as examples, but those skilled in the art may use two or more of them in combination.