Method for applying room temperature modified natural graphite to negative electrode material of lithium battery

Abstract

The application discloses a method for applying normal-temperature modified natural graphite to a lithium battery negative electrode material, and the method is characterized in part by the following steps: (1) adding natural graphite powder into pitch to form a mixture, wherein the ratio of the natural graphite powder to the pitch is 100:(5-20), and loading the mixture and ball materials into a plasma-assisted ball mill tank according to a mass ratio of 10:1; (2) adding anhydrous ethanol as a process control agent, and performing plasma discharge assisted ball milling in a plasma neutral gas atmosphere at 0.1-0.5 atm, wherein the ball milling speed is controlled to be 1000-1500 r / min, the applied electric field voltage is 10-15 KV, the current is 1.0-1.5 A, and the powder is taken out after ball milling for 2-4 h. The crushing process is simple, the energy consumption of the modification process is low, the uniformity is high, and the prepared negative electrode material has good performance.

Description

Technical Field

[0001] This invention relates to the field of anode materials, and in particular to a method for applying room-temperature modified natural graphite to lithium battery anode materials. Background Technology

[0002] Natural graphite, as the name suggests, is graphite formed naturally in the world, generally occurring as graphite schist, graphite gneiss, graphite-bearing schist, and metamorphic shale. The processing properties and uses of graphite are mainly determined by its degree of crystallization. Natural graphite can be divided into two industrial types according to its crystal morphology: crystalline graphite (flake graphite) and cryptocrystalline graphite (earthy graphite).

[0003] Natural graphite spheres all have defects on their surface, so they need to be improved by high-temperature carbonization. High-temperature carbonization modification uses thermal activation to liquefy asphalt powder and uniformly coat the defects on the surface of natural graphite spheres, thereby reducing the degree of surface defects, reducing the specific surface area, improving the rate performance of the anode material and extending the cycle life.

[0004] Currently, the traditional carbonization modification method involves simply mixing the powder coating agent with the material, placing the material in a graphite sagger, and heating it to transform the coating agent into a liquid state that flows randomly to form a stable carbonized coating layer. This method suffers from problems such as uneven coating. Furthermore, traditional methods are time-consuming, energy-intensive, and have poor uniformity.

[0005] Therefore, it is necessary to study a solution to the above problems. Summary of the Invention

[0006] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide a method for applying room-temperature modified natural graphite to lithium battery anode materials, which can effectively solve the problems of uneven coating, long time, high energy consumption and poor uniformity of the existing carbonization modification methods.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for applying room-temperature modified natural graphite to lithium-ion battery anode materials involves modifying natural graphite powder with pitch coating via plasma discharge-assisted ball milling at room temperature. This method achieves the same effect as traditional high-temperature carbonization modification at room temperature and includes the following steps:

[0009] (1) Add natural graphite powder to asphalt and mix to form a material. The ratio of natural graphite powder to asphalt is 100:(5~20). The material and the ball material are loaded into a plasma-assisted ball mill jar at a mass ratio of 10:1.

[0010] (2) Anhydrous ethanol was added as a process control agent, and plasma discharge-assisted ball milling was performed in a neutral plasma atmosphere at 0.1–0.5 atmospheres, controlling the ball milling speed to 1000–

[0011] The powder was removed after ball milling at 1500 r / min, with an applied electric field voltage of 10-15 kV and a current of 1.0-1.5 A for 2-4 hours.

[0012] (3) The powder is demagnetized and sieved to obtain the finished lithium battery negative electrode material.

[0013] As a preferred embodiment, the particle size of the natural graphite powder is 5–50 μm.

[0014] As a preferred embodiment, the natural graphite powder is obtained by crushing, flotation, pulverizing, acid washing, drying, and shaping and screening of natural graphite ore.

[0015] As a preferred option, the asphalt is medium-temperature asphalt.

[0016] As a preferred option, the asphalt is coal tar pitch or petroleum asphalt.

[0017] As a preferred embodiment, the mass ratio of the natural graphite powder to the asphalt is 100:(7-10).

[0018] As a preferred embodiment, the ball mill rotation speed is 1300–1400 r / min.

[0019] As a preferred embodiment, the plasma neutral gas is at least one of argon, nitrogen, and helium.

[0020] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution:

[0021] By using the method of this invention to modify natural graphite at room temperature for use in lithium battery anode materials, the pulverization process involved in the preparation is simplified, the energy consumption required for the modification process is low, the cost is reduced, the resulting product can form a complete core-shell structure with consistent overall uniformity, high equipment reproducibility, and small fluctuations, thereby improving the rate performance of the anode material and extending its cycle life. Detailed Implementation

[0022] This invention discloses a method for applying room-temperature modified natural graphite to lithium battery anode materials. At room temperature, natural graphite powder is modified by asphalt coating through plasma discharge-assisted ball milling, achieving the same effect as traditional high-temperature carbonization modification at room temperature. The method includes the following steps:

[0023] (1) Natural graphite powder is added to asphalt and mixed to form a material. The ratio of natural graphite powder to asphalt is 100:(5-20). The material and ball milling pellets are loaded into a plasma-assisted ball mill jar at a mass ratio of 10:1. The particle size of the natural graphite powder is 5-50 μm. The natural graphite powder is obtained by crushing, flotation, pulverizing, acid washing, drying, and shaping and sieving of natural graphite ore. The asphalt is medium-temperature asphalt, which can be coal tar pitch or petroleum asphalt, or other medium-temperature asphalt. The particle size range of the asphalt is relatively wide and not limited. The preferred mass ratio of natural graphite powder to asphalt is 100:(7-10).

[0024] (2) Anhydrous ethanol is added as a process control agent, and plasma discharge-assisted ball milling is performed in a plasma neutral gas atmosphere at 0.1–0.5 atmospheres. The ball milling speed is controlled at 1000–1500 r / min, the applied electric field voltage is 10–15 kV, and the current is 1.0–1.5 A. The powder is removed after ball milling for 2–4 hours. The preferred ball milling speed is 1300–1400 r / min. The plasma neutral gas is at least one of argon, nitrogen, and helium, and is not limited to any particular gas.

[0025] (3) The powder is demagnetized and sieved to obtain the finished lithium battery negative electrode material.

[0026] The present invention will be further described in detail below with reference to several embodiments:

[0027] Example 1:

[0028] A method for applying room-temperature modified natural graphite to lithium battery anode materials involves modifying natural graphite powder with pitch coating via plasma discharge-assisted ball milling at room temperature, comprising the following steps:

[0029] (1) Natural graphite powder is added to asphalt and mixed to form a material. The ratio of natural graphite powder to asphalt is 100:20. The material and ball milling pellets are loaded into a plasma-assisted ball mill jar at a mass ratio of 10:1. The particle size of the natural graphite powder is 50 μm. The natural graphite powder is obtained by crushing, flotation, pulverizing, acid washing, drying, and shaping and sieving of natural graphite ore. The asphalt is medium-temperature asphalt and is petroleum asphalt. The particle size range of the asphalt is relatively wide and not limited.

[0030] (2) Anhydrous ethanol was added as a process control agent, and plasma discharge assisted ball milling was carried out in a plasma neutral gas atmosphere at 0.2 atmospheres. The ball milling speed was controlled at 1400 r / min, the applied electric field voltage was 15 kV, and the current was 1.5 A. After ball milling for 4 hours, the powder was taken out. The plasma neutral gas was nitrogen.

[0031] (3) The powder is demagnetized and sieved to obtain the finished lithium battery negative electrode material.

[0032] Example 2:

[0033] A method for applying room-temperature modified natural graphite to lithium battery anode materials involves modifying natural graphite powder with pitch coating via plasma discharge-assisted ball milling at room temperature, comprising the following steps:

[0034] (1) Natural graphite powder is added to asphalt and mixed to form a material. The specific gravity of the natural graphite powder is 6.5m. 2 The ratio of natural graphite powder to pitch is 100:10. The material and ball milling pellets are loaded into a plasma-assisted ball mill jar at a mass ratio of 10:1. The particle size of the natural graphite powder is 5 μm. This natural graphite powder is obtained from natural graphite ore through crushing, flotation, pulverization, acid washing, drying, and shaping and sieving. The pitch is medium-temperature pitch, specifically coal tar pitch. The particle size range of the pitch is relatively wide and not limited.

[0035] (2) Anhydrous ethanol was added as a process control agent, and plasma discharge assisted ball milling was carried out in a plasma neutral gas atmosphere at 0.1 atmospheres. The ball milling speed was controlled at 1400 r / min, the applied electric field voltage was 15 kV, and the current was 1.5 A. After ball milling for 4 hours, the powder was taken out. The plasma neutral gas was argon.

[0036] (3) The powder is demagnetized and sieved to obtain the finished lithium battery negative electrode material.

[0037] Example 3:

[0038] A method for applying room-temperature modified natural graphite to lithium battery anode materials involves modifying natural graphite powder with pitch coating via plasma discharge-assisted ball milling at room temperature, comprising the following steps:

[0039] (1) Natural graphite powder is added to asphalt and mixed to form a material. The specific gravity of the natural graphite powder is 6.5m. 2 / g, the specific surface area of ​​natural graphite powder is 6.5m 2 The ratio of natural graphite powder to pitch is 100:5. The material and ball milling pellets are loaded into a plasma-assisted ball mill jar at a mass ratio of 10:1. The particle size of the natural graphite powder is 10 μm. This natural graphite powder is obtained from natural graphite ore through crushing, flotation, pulverization, acid washing, drying, and shaping and sieving. The pitch is medium-temperature pitch, specifically coal tar pitch. The particle size range of the pitch is relatively wide and not limited.

[0040] (2) Anhydrous ethanol was added as a process control agent, and plasma discharge assisted ball milling was carried out in a plasma neutral gas atmosphere at 0.5 atmospheres. The ball milling speed was controlled at 1000 r / min, the applied electric field voltage was 10 kV, and the current was 1.0 A. After ball milling for 2 hours, the powder was taken out. The plasma neutral gas was helium.

[0041] (3) The powder is demagnetized and sieved to obtain the finished lithium battery negative electrode material.

[0042] Example 4:

[0043] A method for applying room-temperature modified natural graphite to lithium battery anode materials involves modifying natural graphite powder with pitch coating via plasma discharge-assisted ball milling at room temperature, comprising the following steps:

[0044] (1) Natural graphite powder is added to asphalt and mixed to form a material. The specific gravity of the natural graphite powder is 6.5m. 2 The ratio of natural graphite powder to asphalt is 100:8. The material and ball milling pellets are loaded into a plasma-assisted ball mill jar at a mass ratio of 10:1. The particle size of the natural graphite powder is 20 μm. This natural graphite powder is obtained from natural graphite ore through crushing, flotation, pulverization, acid washing, drying, and shaping and sieving. The asphalt is medium-temperature asphalt, specifically coal tar pitch. The particle size range of the asphalt is relatively wide and not limited.

[0045] (2) Anhydrous ethanol was added as a process control agent, and plasma discharge assisted ball milling was carried out in a plasma neutral gas atmosphere at 0.4 atmospheres. The ball milling speed was controlled at 1300 r / min, the applied electric field voltage was 10 kV, and the current was 1.2 A. After ball milling for 2.5 h, the powder was taken out. The plasma neutral gas was argon.

[0046] (3) The powder is demagnetized and sieved to obtain the finished lithium battery negative electrode material.

[0047] Example 5:

[0048] A method for applying room-temperature modified natural graphite to lithium battery anode materials involves modifying natural graphite powder with pitch coating via plasma discharge-assisted ball milling at room temperature, comprising the following steps:

[0049] (1) Natural graphite powder is added to asphalt and mixed to form a material. The specific gravity of the natural graphite powder is 6.5m. 2The ratio of natural graphite powder to asphalt is 100:18. The material and ball milling pellets are loaded into a plasma-assisted ball mill jar at a mass ratio of 10:1. The particle size of the natural graphite powder is 30 μm. This natural graphite powder is obtained from natural graphite ore through crushing, flotation, pulverization, acid washing, drying, and shaping and sieving. The asphalt is medium-temperature asphalt, and it is petroleum asphalt. The particle size range of the asphalt is relatively wide and not limited.

[0050] (2) Anhydrous ethanol was added as a process control agent, and plasma discharge assisted ball milling was carried out in a plasma neutral gas atmosphere at 0.3 atmospheres. The ball milling speed was controlled at 1400 r / min, the applied electric field voltage was 14 kV, and the current was 1.4 A. After ball milling for 3.5 h, the powder was taken out. The plasma neutral gas was nitrogen.

[0051] (3) The powder is demagnetized and sieved to obtain the finished lithium battery negative electrode material.

[0052] Example 6:

[0053] A method for applying room-temperature modified natural graphite to lithium battery anode materials involves modifying natural graphite powder with pitch coating via plasma discharge-assisted ball milling at room temperature, comprising the following steps:

[0054] (1) Natural graphite powder is added to asphalt and mixed to form a material. The specific gravity of the natural graphite powder is 6.5m. 2 The ratio of natural graphite powder to asphalt is 100:18. The material and ball milling pellets are loaded into a plasma-assisted ball mill jar at a mass ratio of 10:1. The particle size of the natural graphite powder is 40 μm. This natural graphite powder is obtained from natural graphite ore through crushing, flotation, pulverization, acid washing, drying, and shaping and sieving. The asphalt is medium-temperature asphalt, and it is petroleum asphalt. The particle size range of the asphalt is relatively wide and not limited.

[0055] (2) Anhydrous ethanol was added as a process control agent, and plasma discharge assisted ball milling was carried out in a plasma neutral gas atmosphere at 0.25 atmospheres. The ball milling speed was controlled at 1200 r / min, the applied electric field voltage was 11 kV, and the current was 1.3 A. After ball milling for 3 hours, the powder was taken out. The plasma neutral gas was argon and nitrogen.

[0056] (3) The powder is demagnetized and sieved to obtain the finished lithium battery negative electrode material.

[0057] The materials to be modified in Examples 1 and 2 were mixed with the coating agent in the same proportion and then subjected to conventional high-temperature carbonization modification to obtain Comparative Examples 1 and 2.

[0058] The products obtained from the above embodiments and comparative examples were subjected to physicochemical and electrochemical tests, and the results are shown in Tables 1 and 2. Table 1 shows that the product modified by this method is smaller than the one in Table 2, has more uniform coating, and exhibits less fluctuation in test results. Table 2 shows that the coin cells obtained by this method have advantages over the comparative examples in terms of higher initial efficiency, higher rate capability, and longer cycle life.

[0059] Table 1. Comparison data of multi-point sampling of products from the same batch obtained in each embodiment and comparative example.

[0060]

[0061] Table 2 Comparison of results of each embodiment with Comparative Examples 1 and 2 (button half-cells)

[0062]

[0063] The key design feature of this invention is that by using the method of this invention to modify natural graphite at room temperature for use in lithium battery anode materials, the pulverization process involved in the preparation process is simplified, the energy consumption required for the modification process is low, the cost is reduced, the resulting product can form a complete core-shell structure with consistent overall uniformity, high equipment reproducibility, and small fluctuations, thereby improving the rate performance of the anode material and extending its cycle life.

[0064] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing room-temperature modified natural graphite for use in lithium battery anode materials, characterized in that: Pitch coating modification of natural graphite powder by plasma discharge-assisted ball milling at room temperature includes the following steps: (1) Natural graphite powder is added to asphalt and mixed to form a material. The ratio of natural graphite powder to asphalt is 100:(5-20). The material and ball milling pellets are loaded into a plasma-assisted ball milling jar at a mass ratio of 10:

1. The particle size of the natural graphite powder is 5-50 μm. The natural graphite powder is obtained by crushing, flotation, pulverizing, acid washing, drying and shaping and screening of natural graphite ore. The asphalt is medium-temperature asphalt. The asphalt is coal tar pitch or petroleum asphalt. (2) Add anhydrous ethanol as a process control agent, and perform plasma discharge-assisted ball milling under a plasma neutral gas atmosphere of 0.1 to 0.5 atmospheres. Control the ball milling speed to be 1000-1500 r / min, the applied electric field voltage to be 10-15 kV, and the current to be 1.0-1.5 A. After ball milling for 2-4 hours, take out the powder. The plasma neutral gas is at least one of argon, nitrogen and helium. (3) The powder is demagnetized and sieved to obtain the finished lithium battery negative electrode material.

2. The method according to claim 1, characterized in that: The mass ratio of the natural graphite powder to the asphalt is 100:(7-10).

3. The method according to claim 1, characterized in that: The ball mill rotation speed is 1300-1400 r / min.

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