Preparation method of silicon-carbon negative electrode material
By infiltrating ethoxytrimethylsilane into the pores of activated carbon powder and cracking at high temperature, combined with the use of alkali and water, the contradiction between the economicality and excellent performance of silicon-carbon anode materials in the prior art was solved, and a high-performance silicon-carbon anode material was prepared.
Patent Information
- Application Number
- CN202410057313.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-16
- Publication Date
- 2025-07-18
AI Technical Summary
In the prior art, when preparing silicon-carbon anode materials, there is a contradiction between economicality and excellent performance, and it is difficult to achieve cheap and high-performance preparation at the same time.
Ethoxytrimethylsilane is used to penetrate into the activated carbon powder pores and crack at high temperature. Combined with the use of alkali and water, silicon is formed into the pores of carbon material to improve conductivity and stability, and silicon carbon negative electrode material is prepared through low-temperature baking, calcining and grinding steps.
The preparation of cheap and excellent silicon carbon negative electrode materials is realized, and the conductivity and charge and discharge stability of the material are improved.
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of materials, and more specifically to a method for preparing a silicon-carbon negative electrode material. A method for preparing an industrially applicable silicon-carbon negative electrode with excellent performance is provided, in which silicon produced by pyrolysis is coated in the pores of a carbon material by carbon-rich groups generated during the high-temperature pyrolysis of cheap ethoxytrimethylsilane in the pores of porous carbon. Background Art
[0002] Silicon-carbon negative electrode materials are important materials for improving the performance of lithium-ion batteries at present. How to prepare silicon-carbon negative electrodes with excellent performance using cheap raw materials and simple processes is one of the urgent problems to be solved in lithium-ion batteries at present. Currently, there are various methods for producing silicon-carbon negative electrode materials, mainly including chemical vapor deposition, mechanical ball milling, high-temperature pyrolysis, and sol-gel methods. At present, each of these methods has its own advantages and disadvantages, and there is still room for improvement in terms of economy, material performance, and environmental compatibility. Summary of the Invention
[0003] The object of the present invention is to provide a method for preparing a silicon-carbon negative electrode material with good economy and excellent performance. Liquid ethoxytrimethylsilane penetrates into the pores of an activated carbon source under capillary action and pyrolyzes at high temperature. The generated silicon remains in the pores of the carbon, and the gaseous carbon-rich groups generated by pyrolysis are further pyrolyzed into carbon at high temperature to further coat the silicon in the pores, improving the conductivity of the silicon-carbon negative electrode and its stability during charge and discharge.
[0004] To achieve the above object, the present invention adopts the following technical solutions: The method for preparing a silicon-carbon negative electrode material includes the following steps: 1) uniformly mixing a silicon source added with an additive and an activated carbon powder in a certain proportion; 2) baking the product obtained in step 1 at a low temperature; 3) calcining the product obtained in step 2 in an airtight environment; 4) grinding the product obtained in step 3 to obtain a silicon-based negative electrode material.
[0005] In step 1) of the method: the selected silicon source is ethoxytrimethylsilane, which has a suitable silicon-carbon ratio and good economy; the additive includes an alkali and water, where the alkali is one of sodium hydroxide or potassium hydroxide, the molar ratio of the alkali to water is between 0.001 and 0.05, and the alkali should be fully dissolved in water; the volume ratio of the silicon source to the additive is between 2 and 100.
[0006] In step 1) of the method: the activated carbon powder includes activated pitch-based, coal-based, resin-based, and biomass-based carbon; the activation temperature is higher than 900 °C; the maximum particle size of the activated carbon powder is less than 30 microns so that the silicon source can fully penetrate into the pores of the carbon powder; the activated carbon powder may or may not be graphitized.
[0007] The method step 1): The mass ratio between the silicon source with additives and the activated carbon powder is between 0.05 and 0.3, and the specific ratio depends on the pore structure of the activated carbon powder.
[0008] The method step 2): The baking temperature is 50 - 80 °C, and the baking time is 24 to 120 hours. During this process, ethoxytrimethylsilane should be fully polymerized.
[0009] The method step 3): The air - isolation environment is an inert gas - protected atmosphere, or an atmosphere that can ensure the carbon material is not oxidized, including a carbon dioxide atmosphere or a semi - sealed environment covered with carbon powder; the calcination temperature is 500 to 1200 °C, the heating rate during the heating process is not faster than 50 °C / min, and the heat - preservation time is 1h - 10h.
[0010] The method step 4): The method used for grinding is a jet mill, and the maximum particle size of the ground powder is less than 30 microns.
[0011] In summary, according to the preparation method of a silicon - carbon anode material provided by the present invention, a silicon - carbon anode material with good economy and excellent performance can be prepared using inexpensive raw materials, simple equipment, and a simple process. Description of the Drawings Figure 1: The preparation flow chart of this embodiment.
Claims
1. A preparation method of a silicon-carbon anode material, characterized in that: The specific preparation steps are as follows: Step 1, uniformly mix the silicon source added with additives and the activated carbon powder in a certain proportion; Step 2, bake the product obtained in Step 1 at a low temperature; Step 3, calcine the product obtained in Step 2 in an air-insulated environment; Step 4, grind the product obtained in Step 3 to obtain the silicon-based anode material.
2. The preparation method of a silicon-carbon anode material according to claim 1, characterized in that: In Step 1, the silicon source is ethoxymethyltrimethylsilane; the additives include an alkali and water, where the alkali is one of sodium hydroxide or potassium hydroxide, and the molar ratio of the alkali to water is between 0.001 and 0.05; the volume ratio of the silicon source to the additives is between 2 and 100.
3. The preparation method of a silicon-carbon anode material according to claim 1, characterized in that: In Step 1, the activated carbon powder includes activated pitch-based, coal-based, resin-based, and biomass-based carbon; the activation temperature is higher than 900 °C; the maximum particle size of the activated carbon powder is less than 30 microns; the activated carbon powder may or may not be graphitized.
4. The preparation method of a silicon-carbon negative electrode material according to claim 1, wherein: In Step 1, the mass ratio between the silicon source added with additives and the activated carbon powder is between 0.005 and 0.
3.
5. The preparation method of a silicon-carbon anode material according to claim 1, characterized in that: In Step 2, the baking temperature is 50 - 80 °C, and the baking time is 24 to 120 hours.
6. The preparation method of a silicon-carbon anode material according to claim 1, characterized in that: In Step 3, the air-insulated environment is an inert gas protection atmosphere, or an atmosphere that can ensure that the carbon material is not oxidized, including a carbon dioxide atmosphere or a semi-sealed environment covered with carbon powder; the calcination temperature is 500 to 1200 °C, the heating rate during the heating process is not faster than 50 °C / min, and the heat preservation time is 1h - 10h.
7. The preparation method of a silicon-carbon anode material according to claim 1, wherein: In Step 4, the method used for grinding is a jet mill, and the maximum particle size of the ground powder is less than 30 microns.