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Silicon-carbon composite material and preparation method thereof, and lithium ion battery

A silicon-carbon composite material, silicon-based material technology, applied in battery electrodes, secondary batteries, circuits, etc., can solve the problems of volume expansion, material structure damage, silicon volume change, etc., achieve easy control, improve rate performance, diffusion good performance

Inactive Publication Date: 2015-07-08
CHERY AUTOMOBILE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, during the charging and discharging process of the battery, the intercalation and extraction cycles of lithium will cause a huge change in the volume of silicon, and the serious volume expansion and contraction of silicon will cause the destruction of the material structure and the pulverization of the material, which will lead to poor cycle performance of lithium-ion batteries. the sharp decline of

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0030] (1) Put silicon powder with a particle size of 50nm into a high-pressure reactor, which is a high-pressure environment, and then use a high-pressure pump to pump the carbon dioxide supercritical fluid that dissolves ethyl cellulose into the high-pressure reactor In the still, wherein, the quality of ethyl cellulose accounts for 1.7% of the total mass of ethyl cellulose and carbon dioxide supercritical fluid. Under the conditions of 50°C and 8MPa, stir for 2 hours to obtain a mixture of silicon powder, ethyl cellulose, and carbon dioxide supercritical fluid;

[0031] (2) Connect the high-pressure reactor to the expansion chamber (i.e., a pressure-releasing airtight container), and the mixture enters the expansion chamber to obtain a composite material of ethyl cellulose-coated silicon powder;

[0032] (3) Carbonize the composite material of ethyl...

Embodiment 2

[0038] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0039] (1) Put silicon monoxide with a particle size of 20nm into a high-pressure reactor, which is a high-pressure environment, and then use a high-pressure pump to pump the carbon dioxide supercritical fluid that dissolves ethyl cellulose and methyl cellulose into the autoclave (wherein the mass ratio of ethyl cellulose to methyl cellulose is 1:1), wherein the mass ratio of ethyl cellulose and methyl cellulose accounts for ethyl cellulose, methyl cellulose 5% of the total mass of base cellulose and carbon dioxide supercritical fluid. Stir for 24 hours at -10°C and 6MPa to obtain a mixture of silicon monoxide, ethyl cellulose, methyl cellulose, and carbon dioxide supercritical fluid;

[0040](2) Connecting the high-pressure reactor to a pressure-releasing airtight container, and the mixture enters the pressure-releasing airtight container to obtain a ...

Embodiment 3

[0045] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0046] (1) Put a mixture of silicon powder and silicon monoxide with a particle size of 100nm (the mass ratio of silicon powder and silicon monoxide is 2:1) into a high-pressure reactor, which is a high-pressure environment , and then use a high-pressure pump to pump the water supercritical fluid dissolving polyvinyl alcohol into the high-pressure reactor, wherein the quality of polyvinyl alcohol accounts for 6% of the total mass of polyvinyl alcohol and water supercritical fluid. Stir for 10 hours at 60°C and 4MPa to obtain a mixture of silicon powder, silicon monoxide, polyvinyl alcohol, and water supercritical fluid;

[0047] (2) Connect the high-pressure reactor to the expansion chamber, and the mixture enters the expansion chamber to obtain a composite material of polyvinyl alcohol-coated silicon powder and silicon monoxide mixture;

[0048] (3) C...

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Abstract

The present invention discloses a silicon-carbon composite material and a preparation method thereof, and a lithium ion battery. The method comprises that: (1) a silicon-based material is placed into an autoclave, wherein a high-pressure environment exists in the autoclave; and a supercritical fluid having the dissolved organic carbon precursor is pumped into the autoclave by using a high pressure pump to obtain a mixture; (2) the autoclave is communicated with a pressure-releasing sealed container, and the mixture enters the pressure-releasing sealed container to obtain an organic carbon precursor-coated silicon-based material composite material; and (3) high temperature carbonization is performed under a non-oxidizing atmosphere to obtain the silicon-carbon composite material. According to the present invention, with the supercritical fluid, the organic carbon precursor is completely dispersed, such that the organic carbon precursor and the silicon-based material are uniformly mixed, the binding force is increased, the volatilizing gas-state supercritical carbon dioxide can be continuously reused after entering the pressure-releasing sealed container, and no impurity is introduced into the organic carbon precursor and silicon-based material mixture so as to further improve the rate capability of the battery.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a silicon-carbon composite material, a preparation method thereof, and a lithium-ion battery. Background technique [0002] In recent years, with the increasingly serious energy and environmental problems and the requirement of light weight electronic products, people's research on lithium-ion batteries has been deepening. Traditional lithium-ion batteries usually include four components: positive electrode, negative electrode, separator and electrolyte. Common lithium-ion battery positive electrode materials usually choose lithium-containing active compounds, and negative electrode materials are selected from carbon-based materials. When charging, the potential difference applied to the two poles of the battery forces the active material in the positive electrode to release lithium ions, which are embedded in the layered structure of the negative elect...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M10/0525
CPCH01M4/364H01M10/0525Y02E60/10
Inventor 卢磊朱广燕陈效华
Owner CHERY AUTOMOBILE CO LTD
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