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Silicon-carbon composite material, and preparation method and application thereof

A technology of silicon-carbon composite materials and carbon sources, applied in nanotechnology, nanotechnology, structural parts, etc. for materials and surface science, can solve problems such as unsuitable preparation process, poor cycle stability, and low tap density. Achieve the effects of good industrialization prospect, low cost and simple preparation method

Active Publication Date: 2021-04-13
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] A main purpose of the present invention is to overcome at least one defect of the above-mentioned prior art, and provide a silicon-carbon composite material and a preparation method thereof. The silicon-carbon composite material adopts the design of a multi-layer buffer structure, and is used as a negative electrode material of a lithium-ion battery It can effectively solve the problems of low tap density, poor cycle stability, high cost and unsuitable preparation process for industrial production of existing silicon-carbon composite materials.

Method used

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  • Silicon-carbon composite material, and preparation method and application thereof
  • Silicon-carbon composite material, and preparation method and application thereof
  • Silicon-carbon composite material, and preparation method and application thereof

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preparation example Construction

[0033] The first aspect of the present invention provides a method for preparing a silicon-carbon composite material, comprising the following steps: pulverizing and dealloying a silicon-based alloy to obtain micron silicon powder; dispersing the micron silicon powder in a solution containing a first carbon source, After pulverization, the nano-silicon slurry with primary coating is obtained; the nano-silicon slurry is mixed with the second carbon source, stirred evenly, dried and roasted to obtain the precursor of the secondary coating; the precursor is in the atmosphere of the third carbon source Under chemical vapor deposition, a three-level coated silicon-carbon composite material is obtained.

[0034] According to the present invention, as mentioned above, there is a silicon-carbon composite technology using nano-silicon to improve the volume expansion of silicon during charging and discharging, so as to improve the cycle stability of the material. However, nano-silicon o...

Embodiment 1

[0056] (1) Put 50g of Al-Si alloy block (Si content is 60wt%) in the ball mill pot, put stainless steel grinding balls in the ratio of 15:1 according to the mass ratio of ball to material, feed nitrogen as protective gas, and then use 200rpm ball milling at a high speed for 24 hours to obtain Al-Si alloy powder. Add Al-Si alloy powder to a concentration of 1mol L -1 etched in hydrochloric acid, filtered, washed with water, and dried in vacuum at 50°C to obtain micron silicon powder;

[0057] (2) Take 100g of citric acid and dissolve it in 2L of isopropanol, then add 100g of the micron silicon powder prepared in step (2), mix it uniformly by ultrasonic, pour it into the dispersion tank of a sand mill, and sand mill it at 2300rpm for 8h under the protection of nitrogen After taking out, obtain the nano-silicon slurry coated with citric acid;

[0058] (3) Put 14g of spherical graphite and 4g of asphalt into 150mL of the slurry prepared in step (2), stir and mix evenly, then dry...

Embodiment 2

[0064] (1) Put 50g of Fe-Si alloy block (Si content is 75wt%) in the ball mill jar, put stainless steel grinding balls in the ratio of 20:1 according to the mass ratio of ball to material, feed nitrogen as protective gas, and then use 400rpm ball milling for 12 hours at a high speed to obtain Fe-Si alloy powder. Add Fe-Si alloy powder to a concentration of 2mol L -1 etched in hydrochloric acid, filtered, washed with water, and dried in vacuum at 50°C to obtain micron silicon powder;

[0065] (2) Take 100g of glucose and dissolve it in 2L of ethanol, then add 100g of micron silicon powder prepared in step (2), mix it uniformly by ultrasonic, pour it into the dispersion tank of a sand mill, and take it out after sand milling at 2500rpm for 4 hours under the protection of nitrogen. Obtain the nano-silicon slurry coated with glucose;

[0066] (3) Put 15g of spherical graphite and 5g of asphalt into 150mL of the slurry prepared in step (2), stir and mix evenly, then dry, and fina...

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Abstract

The invention provides a preparation method of a silicon-carbon composite material. The preparation method comprises the following steps: pulverizing a silicon-based alloy, and carrying out dealloying to obtain micron silicon powder; dispersing the micron silicon powder into a solution containing a first carbon source, and performing crushing treatment to obtain primary coated nano silicon slurry; mixing the nano silicon slurry with a second carbon source, uniformly stirring, drying and roasting to obtain a secondary coated precursor; and carrying out chemical vapor deposition on the precursor in a third carbon source atmosphere to obtain the three-stage coated silicon-carbon composite material. The silicon-carbon composite material can be used as a good lithium ion battery negative electrode active material, by constructing multiple buffer coating layers, the high capacity and the first coulombic efficiency of the battery are ensured, meanwhile, the long cycle stability is effectively improved, the tap density can also be kept at a relatively high level, and the silicon-carbon composite material has very good comprehensive performance. The preparation method is simple and low in cost, and the preparation process is suitable for large-scale production and has a good industrial prospect.

Description

technical field [0001] The invention relates to battery material technology, in particular to a silicon-carbon composite material and its preparation method and application. Background technique [0002] Lithium-ion batteries have become an important part of modern communications, portable electronic products and hybrid power because of their advantages such as high specific energy, long charge and discharge life, no memory effect, low self-discharge rate, fast charging, no pollution, wide operating temperature range and safety and reliability. Ideal chemical power supply for automobiles etc. The current commercial anode material is graphite, with a theoretical specific capacity of 372mAh g -1 , can no longer meet the needs of high-energy-density batteries, so it is urgent to develop high-capacity negative electrode active materials. [0003] Silicon can be alloyed with lithium at room temperature to form Li 15 Si 4 phase, the theoretical specific capacity is as high as ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525B82Y30/00
CPCH01M4/366H01M4/386H01M4/625H01M10/0525B82Y30/00Y02E60/10
Inventor 陈旭冯晓磊杨文胜孙伟航林伟国荣峻峰杜泽学
Owner CHINA PETROLEUM & CHEM CORP
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