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Silicon-carbon composite material, preparation thereof, battery cathode and lithium ionic cell

A silicon-carbon composite material and composite material technology, applied in battery electrodes, circuits, electrical components, etc., can solve the problems of poor cycle performance of negative electrodes, and achieve the effects of easy process, high specific capacity, and excellent cycle performance.

Active Publication Date: 2009-05-27
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The object of the present invention is to provide a lithium-ion battery negative electrode active material with higher capacity and excellent cycle performance and its preparation method in order to overcome the shortcomings of the poor cycle performance of the lithium-ion battery negative electrode made of silicon-carbon composite materials in the prior art

Method used

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Examples

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Effect test

preparation example Construction

[0013] The preparation method of the silicon-carbon composite material provided by the invention comprises dispersing nano-silicon and carbon nanotubes in a dispersant, removing the dispersant to obtain nano-silicon / carbon nanotube composite particles; combining nano-silicon / carbon nanotube composite particles with no The amorphous carbon precursor solution is contacted, the solvent is removed, and the amorphous carbon precursor is charred.

[0014] The particle diameter of the nano-silicon is 20-100 nanometers; the diameter of the carbon nanotube is 20-100 nanometers, and the length is 0.5-2 microns.

[0015] The dispersant used for dispersing nano-silicon and carbon nanotubes can be various liquids capable of dispersing nano-silicon and carbon nanotubes, for example, it can be water, ethanol, propanol, propylene glycol or their mixtures. The dosage of the dispersant is 1-15 liters of dispersant per 100 grams of nano-silicon.

[0016] The amount of nano-silicon, carbon nanot...

Embodiment 1

[0039] This example is used to illustrate the preparation of the composite material for lithium ion battery negative electrode provided by the present invention.

[0040] (1) Preparation of nano-silicon / carbon nanotube composite particles

[0041] Add 600 milliliters of deionized water, 150 milliliters of ethanol and 20 grams of polyvinyl alcohol successively into a 1500 milliliter beaker. After stirring for 30 minutes, slowly add a mixture containing 10 grams of nano-silicon and 0.6 grams of carbon nanotubes under stirring conditions. Nano-silicon The particle diameter is 20-50 nanometers, the carbon nanotube diameter is 20-50 nanometers, and the length is 1-2 micrometers. After stirring for 40 minutes, filter and dry at 80°C.

[0042] (2) Contacting the composite particles with the amorphous carbon precursor solution

[0043] Add the nano-silicon / carbon nanotube composite particles obtained in step (1) into a pre-stirred solution containing 15 grams of epoxy resin and 400 m...

Embodiment 2

[0047] This example is used to illustrate the preparation of the composite material for lithium ion battery negative electrode provided by the present invention.

[0048] (1) Preparation of nano-silicon / carbon nanotube composite particles

[0049] Using the same method as in Example step (1), the difference is that 80 milliliters of ethanol is added; 20 grams of polyvinyl pyrrolidone is used instead of 20 grams of polyvinyl alcohol; and the amount of carbon nanotubes is changed to 2 grams.

[0050] (2) Contacting the composite particles with the amorphous carbon precursor solution

[0051] With the method identical with embodiment step (2), difference is to replace the solution that contains 15 grams of epoxy resins and 400 milliliters of ethanols with 1000 milliliters of tetrahydrofuran solutions containing 24 grams of bitumen.

[0052] (3) Solvent removal and carbonization

[0053] With the method identical with embodiment step (3), 34 grams of products are denoted as E2. ...

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Abstract

The invention relates to a silicon-carbon composite material, which contains nano-silicon / carbon nanotube composite particles and amorphous carbon, wherein the amorphous carbon is coated on the surfaces of the composite particles. A method for preparing the material comprises the following steps: dispersing the nano-silicon and the carbon nanotubes in a dispersant, and removing the dispersant to obtain the nano-silicon / carbon nanotube composite particles; and contacting the nano-silicon / carbon nanotube composite particles with an amorphous carbon precursor solution, and removing a solvent to carbonize the amorphous carbon precursor. The invention also provides a negative pole of a lithium ion cell made from the composite material. The method for preparing the composite material is simple,the process is easy to control, and a cell made of the negative pole made from the composite material has a lower first irreversible specific capacity, higher specific capacity and excellent cycling performance.

Description

technical field [0001] The invention relates to a silicon-carbon composite material and a preparation method thereof, as well as a battery negative pole and a lithium ion battery made of the material. Background technique [0002] With the development of the electronic information industry, the miniaturization and high-performance development of electronic equipment has continuously increased the requirements for battery capacity density. In addition, because the capacity of carbon-based negative electrode materials is almost close to the theoretical value of 372mAh / g, people pay attention to Invested in metals such as silicon, tin, aluminum and antimony that can electrochemically alloy with lithium. Among them, silicon is the most attractive one, with a theoretical capacity as high as 4200mAh / g. However, their volume expands and contracts during the process of intercalation and extraction of lithium ions, which leads to poor electrical contact between the active material a...

Claims

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Application Information

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IPC IPC(8): C04B35/628C04B35/515H01M4/04H01M4/58
CPCY02E60/12Y02E60/10
Inventor 陈争光沈菊林魏剑锋
Owner BYD CO LTD
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