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Core-shell structure silicon carbon composite material and preparation method thereof

A silicon-carbon composite material, core-shell structure technology, applied in structural parts, electrical components, battery electrodes, etc., can solve the problems of reducing specific capacity and rate performance, affecting lithium ion interface transfer, and reducing material specific capacity, etc. Conductivity, preventing breakage and scattering, and ensuring stability

Active Publication Date: 2016-11-09
湖南宸宇富基新能源科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in the process of preparing silicon-carbon composite materials, since magnesia thermal reduction is an exothermic reaction, local heat accumulation will lead to side reactions in the system and generate silicon carbide impurity phases.
Silicon carbide has no reactivity with lithium, which will not only lead to a decrease in the specific capacity of the material, but also affect the interfacial transfer of lithium ions in the electrode material
This greatly reduces the specific capacity and rate capability of the as-prepared materials

Method used

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  • Core-shell structure silicon carbon composite material and preparation method thereof
  • Core-shell structure silicon carbon composite material and preparation method thereof
  • Core-shell structure silicon carbon composite material and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0052] Take 1g of silica balls with a diameter of about 250nm as raw materials, mix them with 0.8g of metal magnesium powder, place them in a closed environment filled with argon, and raise the temperature to 700°C at a heating rate of 5°C / min for 6 hours. After the reaction, the product was taken out and dissolved in 1mol / L hydrochloric acid to react for 6h. After filtering and drying, the intermediate product Si@SiO obtained above was 2 Dissolve it with phenolic resin in ethanol solvent at a mass ratio of 1:1, stir at 80°C until the ethanol is completely volatilized, grind the mixture finely, and then raise the temperature to 800°C at a heating rate of 5°C / min for 2 hours in an argon atmosphere. . The product obtained after the reaction is C@Si@SiO 2 It was dissolved in 5% hydrofluoric acid and reacted for 0.5h, filtered, washed and dried to obtain the reaction product C@Si. The X-ray diffraction pattern of its product C@Si is as follows image 3 As shown, the transmissi...

Embodiment 2

[0055] Take 1g of silica balls with a diameter of about 100nm as the raw material, mix them evenly with 0.5g of metal magnesium powder, place them in a closed environment filled with argon and hydrogen, and raise the temperature to 650°C at a rate of 2°C / min to react for 2h . After the reaction, the product was taken out and dissolved in 0.5 mol / L sulfuric acid to react for 4 hours. After filtration and drying, the intermediate product Si@SiO obtained above 2 Dissolve in the aqueous solvent with sucrose at a mass ratio of 1:10, stir at 100°C until the water evaporates completely, grind the mixture finely, and raise the temperature to 700°C at a heating rate of 10°C / min for 4 hours under nitrogen atmosphere. The product obtained after the reaction is C@Si@SiO 2 Dissolve in hydrofluoric acid with a mass fraction of 2% and react for 2 hours, filter, wash and dry to obtain the reaction product C@Si. The diameter of the porous nano-silicon core of the obtained product is about 1...

Embodiment 3

[0058] Take 1g of silica particles with a diameter of about 500nm as a raw material, mix it with 0.7g of metal magnesium powder, place it in a closed environment filled with argon, and raise the temperature to 700°C at a heating rate of 10°C / min for 4 hours. After the reaction, the product was taken out and dissolved in 2mol / L hydrochloric acid for 8 hours. After filtration and drying, the intermediate product Si@SiO obtained above 2 Dissolve polyvinyl alcohol in n-butanol solvent at a mass ratio of 1:15, stir at 90°C until the ethanol is completely volatilized, grind the mixture finely, and heat up at a rate of 20°C / min under a mixed atmosphere of argon and nitrogen The temperature was raised to 900°C for 6 hours. The product obtained after the reaction is C@Si@SiO 2 Dissolve in hydrofluoric acid with a mass fraction of 10% and react for 0.5 h, filter, wash and dry to obtain the reaction product C@Si. The diameter of the porous nano-silicon core of the obtained product is ...

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Abstract

The invention discloses a core-shell structure silicon carbon composite material and a preparation method thereof. The composite material is of a core-shell structure. The core-shell structure includes a shell composed of a carbon layer and a core composed of porous nano silicon. An air gap layer is arranged between the shell and the core. The preparation method comprises the steps that silicon dioxide particles perform magnesiothermic reduction reaction through magnesium powder, a reduction product is subjected to in-situ coating through an organic macromolecular carbon source, then carbonization is performed, and a carbonization product is corroded with hydrofluoric acid to obtain the silicon carbon composite material. The silicon carbon composite material has good stability, can well buffer silicon volume expansion and improve material conductivity, and thus ensures the cycle stability of electrodes. The silicon carbon composite material preparation process is simple and is suitable for industrial production, and the raw materials are wide in source.

Description

technical field [0001] The invention relates to a preparation method of a lithium-ion battery negative electrode material, in particular to a silicon-carbon composite material with a core-shell structure and a preparation method thereof, belonging to the technical field of lithium-ion batteries. Background technique [0002] Since the beginning of the 21st century, with the development of society and the advancement of technology, electronic products, electric vehicles and energy storage power stations increasingly require lithium-ion batteries with high energy density and long life. However, graphite-based negative electrode materials are widely used in commercial lithium-ion batteries at present, and their theoretical capacity is low (372mAh / g), which is difficult to meet the demand. As an anode material, silicon has a very high theoretical specific capacity (4200mAh / g), which has attracted extensive attention from researchers. During the charge and discharge process of s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/62
CPCH01M4/62H01M4/625Y02E60/10
Inventor 杨娟周向阳吴李力任永鹏聂阳陈松
Owner 湖南宸宇富基新能源科技有限公司
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