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Method for preparing amorphous silicon/carbon composite material

A carbon composite material and amorphous silicon technology, applied in the preparation/purification of carbon, silicon compounds, chemical instruments and methods, etc., can solve problems such as environmental pollution, expensive and dangerous, achieve optimized preparation process, and be easy for industrial implementation , excellent cycle stability and rate performance

Active Publication Date: 2020-01-21
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Acetylene is commonly used in laboratories to decompose and wrap carbon. This method is expensive and has certain risks. However, the use of asphalt to decompose and wrap carbon in industry also has the problem of environmental pollution.

Method used

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  • Method for preparing amorphous silicon/carbon composite material
  • Method for preparing amorphous silicon/carbon composite material
  • Method for preparing amorphous silicon/carbon composite material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Under the condition of nitrogen atmosphere protection, the magnesium silicide and lithium carbonate with a mass ratio of 2:1 were ball-milled at a speed of 500r / min with a ball-to-material ratio of 30:1 for 24 hours, and then the ball-milled uniform mixture was transferred to a closed reactor ; Then rise to 300°C at a heating rate of 5°C / min for 2 hours and then cool to room temperature;

[0030] The product was sequentially soaked in 1M dilute hydrochloric acid for 4 hours, washed with deionized water and alcohol for 4 times each, then suction-filtered, and vacuum-dried at 80°C to obtain an amorphous silicon / carbon composite material. figure 1 The curves of temperature and pressure versus time during the preparation of the material. figure 2 It is the XRD diffraction pattern of this material, and the steamed bread peaks around 23° and 27° correspond to amorphous carbon and amorphous silicon in turn. image 3 It is a scanning electron microscope (SEM) photo of the pre...

Embodiment 2

[0033] Under the protective condition of argon atmosphere, magnesium silicide and potassium carbonate with a mass ratio of 0.5:1 were ball-milled at a speed of 400r / min with a ball-to-material ratio of 10:1 for 12 hours, and then the ball-milled uniform mixture was transferred to a closed reaction device; then rise to 100°C at a heating rate of 0.5°C / min for 0.5h and then cool to room temperature;

[0034] The product was sequentially soaked in 1M dilute hydrochloric acid for 4 hours, washed with deionized water and alcohol for 4 times each, then suction-filtered, and vacuum-dried at 70°C to obtain an amorphous silicon / carbon composite material.

[0035] Using the amorphous silicon / carbon composite material obtained in Example 1, an electrode was prepared in the following manner. Amorphous silicon / carbon composite material: super-P: polytetrafluoroethylene was weighed at a mass ratio of 80:10:10, and ground evenly to make an electrode. The metal lithium sheet was used as the c...

Embodiment 3

[0037] Under the protective condition of nitrogen atmosphere, under the protective atmosphere, the mass ratio of magnesium silicide and magnesium carbonate with a mass ratio of 10:1 was ball-milled at a speed of 500r / min with a ball-to-material ratio of 80:1 for 108h, and then the ball-milled uniform mixture was transferred to Airtight reactor; then rise to 500°C at a heating rate of 10°C / min for 5 hours and then cool to room temperature;

[0038] The product was sequentially soaked in 1M dilute hydrochloric acid for 4 hours, washed with deionized water and alcohol for 4 times each, then suction-filtered, and vacuum-dried at 80°C to obtain an amorphous silicon / carbon composite material.

[0039] Using the amorphous silicon / carbon composite material obtained in Example 1, an electrode was prepared in the following manner. Amorphous silicon / carbon composite material: super-P: polytetrafluoroethylene was weighed at a mass ratio of 80:10:10, and ground evenly to make an electrode....

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Abstract

The invention relates to a method for preparing an amorphous silicon / carbon composite material by using magnesium silicide as a raw material and application of the amorphous silicon / carbon composite material as a lithium ion battery negative electrode material. Amorphous silicon can better buffer silicon volume expansion and enhance structural stability, and is one of the most potential high-specific-capacity lithium ion battery negative electrode materials, and carbon coating is one of important means for modifying a silicon negative electrode. In the invention, the green and environment-friendly raw material, carbonate, is used as a carbon source, wherein the magnesium decomposed from magnesium silicide is subjected to a reduction reaction with carbonate, and the carbonate is deposited on the surfaces of silicon particles while being reduced into carbon, so that the two steps of amorphous silicon preparation and carbon coating are integrated; therefore, the preparation process is optimized, and the silicon / carbon composite material with performance advantages is obtained as well. The discharge capacity of the prepared amorphous silicon / carbon composite material is close to 570 mAh / g after 970 cycles at 1 A / g, and the amorphous silicon / carbon composite material has excellent cycle performance and rate capability.

Description

technical field [0001] The invention relates to a method for preparing an amorphous silicon / carbon composite material by using magnesium silicide as a raw material and its application as a lithium ion battery negative electrode material. Background technique [0002] "Made in China 2025" proposes that by 2020, the specific energy of lithium-ion batteries in my country will reach 300 Wh / kg. Therefore, lithium-ion batteries with high specific energy have become the focus of research and development, and silicon-based negative electrode materials may become a breakthrough for high specific capacity negative electrodes. Graphite carbon materials are limited by their relatively low theoretical specific capacity (374mAh / g), and lithium dendrites may form on the surface of the negative electrode under high current charging. People are eagerly hoping for the emergence of a new generation of higher specific capacity negative electrodes. As a typical representative of alloyed anode, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/021C01B32/05H01M4/38H01M4/62H01M10/0525
CPCC01B33/021C01B32/05H01M4/386H01M4/625H01M10/0525Y02E60/10
Inventor 黄辉余佳阁甘永平张俊夏阳梁初张文魁卞飞翔
Owner ZHEJIANG UNIV OF TECH
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