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Method for preparing silicon-carbon composite material by molten salt assisted magnesiothermic reduction

A technology of silicon-carbon composite materials and composite materials, applied in the direction of nanotechnology, active material electrodes, nanotechnology, etc. for materials and surface science, can solve the problems of complex process and high reduction temperature, so as to improve electronic conductivity and reduce Formation of silicon carbide, effect of alleviating volume expansion effect

Active Publication Date: 2021-03-02
NORTHWEST NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The reduction temperature used in this patent is high, and the process is relatively complicated. The preparation process is to obtain silicon simple substance by high-temperature reduction, and then carbonize and coat it to prepare silicon-carbon composite materials.

Method used

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  • Method for preparing silicon-carbon composite material by molten salt assisted magnesiothermic reduction
  • Method for preparing silicon-carbon composite material by molten salt assisted magnesiothermic reduction
  • Method for preparing silicon-carbon composite material by molten salt assisted magnesiothermic reduction

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Embodiment 1

[0023] (1) First, attapulgite was dried at 200 °C to remove water, washed with 4 mol / L HCl solution, and then 2 g of pretreated attapulgite was uniformly dispersed in 300 mL of ethanol-water mixed solution (V 乙醇 : V 水 = 1:4) to obtain attapulgite dispersion; dissolve 2 g of sodium alginate in 100 ml of deionized water to form a sodium alginate solution; mix the attapulgite dispersion and sodium alginate solution, stir dry, and place under inert gas protection and carbonization at 800 °C for 5 h to obtain an amorphous carbon coating-coated attapulgite composite material.

[0024] (2) Mix the amorphous carbon coating-coated attapulgite composite material with magnesium powder in a mass ratio of 1:1, and mix and grind it with potassium chloride in a mass ratio of 1:15, and react at 650 ° C under the protection of inert gas. 5h, cooled to room temperature, then washed with hydrochloric acid and hydrofluoric acid, and finally washed with deionized water and absolute ethanol, and d...

Embodiment 2

[0027] (1) First, attapulgite was dried at 300 °C to remove water, washed with 8 mol / L HCl solution, and then 4 g of pretreated attapulgite was uniformly dispersed in 300 mL of ethanol-water mixed solution (V 乙醇 : V 水 = 1:4) to obtain attapulgite dispersion; dissolve 2 g of potassium alginate in 100 ml of deionized water to form a potassium alginate solution; mix the attapulgite dispersion and potassium alginate solution, stir dry, and place under inert gas protection and carbonization at 900 °C for 2 h to obtain an amorphous carbon coating-coated attapulgite composite material.

[0028] (2) Mix the amorphous carbon coating-coated attapulgite composite material with magnesium powder in a mass ratio of 1:3, and mix and grind it with potassium chloride in a mass ratio of 1:25, and react at 750 ° C under the protection of inert gas. 6h, cooled to room temperature, then washed with hydrochloric acid and hydrofluoric acid, and finally washed with deionized water and absolute ethan...

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Abstract

The invention provides a method for preparing a silicon-carbon composite material by molten salt assisted magnesiothermic reduction, and the method comprises the following steps: by using alginate andattapulgite as raw materials, carrying out high-temperature carbonization to obtain an amorphous carbon coating coated attapulgite composite material, adding a reducing agent and molten salt, carrying out heat assisted reduction reaction, and carrying out acid washing treatment to obtain the silicon-carbon composite material. According to the method for preparing the silicon-carbon composite material by combining high-temperature carbonization and low-temperature molten salt heat assistance, the generation of silicon carbide is effectively reduced through molten salt heat-assisted reduction reaction, silicon nanoparticles reduced by attapulgite are coated with a carbon coating in the prepared silicon-carbon composite material, and a gap structure is formed through acid etching. The composite material is used as a lithium ion battery negative electrode material, the volume expansion effect caused in the lithium intercalation and deintercalation process can be effectively relieved through a carbon layer, gaps and a porous structure, and meanwhile, the electronic conductivity is improved, so that the composite material has excellent electrochemical lithium storage performance.

Description

technical field [0001] The invention relates to a method for preparing a silicon-carbon composite material by molten salt-assisted magnesium thermal reduction. The silicon-carbon composite material is mainly used as a negative electrode material of a lithium ion battery, and belongs to the technical field of composite materials and the technical field of new energy. Background technique [0002] The endurance of new energy vehicles and electronic products depends on the energy density of the battery. With the continuous improvement of consumer demand, automobiles and electronic products with long endurance are very popular among consumers. Therefore, the pursuit of batteries with high energy density will become the direction and driving force of future development. Among all the materials that can fulfill this requirement, silicon-based materials are one of the most candidates due to their high theoretical capacity (Si, 4200 mAh g -1 ), low operating potential, wide source ...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/583H01M10/0525B82Y30/00
CPCH01M4/366H01M4/386H01M4/583H01M10/0525B82Y30/00H01M2004/027Y02E60/10
Inventor 周小中田继斌祁赵一刘强费莎莎鲁鸿凯丁娟霞雷自强
Owner NORTHWEST NORMAL UNIVERSITY
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