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A method for in-situ preparation of porous silicon-carbon composites

A carbon composite material, in-situ preparation technology, applied in nanotechnology, structural parts, electrical components, etc. for materials and surface science, can solve problems such as high cost, complex equipment requirements, unfavorable mass production and industrialization, etc. achieve uniform size

Active Publication Date: 2020-11-17
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the industry, the silicon-carbon composite negative electrode material generally adopts the ball milling method, and the silicon raw material and the graphite carbon material are directly ball-milled. Although the silicon-carbon composite material formed in this way can improve its capacity fading problem, the overall capacity is low.
Although the vapor deposition method and the silane decomposition method can obtain better electrochemical performance, the cost in industrial production is high, and the equipment requirements are complicated, which is not conducive to large-scale production and industrialization.

Method used

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  • A method for in-situ preparation of porous silicon-carbon composites
  • A method for in-situ preparation of porous silicon-carbon composites
  • A method for in-situ preparation of porous silicon-carbon composites

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] 1. Add 0.2g PEI (Mw=70000) into a mixed solvent composed of 30mL ethanol and 2mL water, stir at room temperature for 1h to obtain a mixed solution;

[0054] 2. While stirring, slowly add tetraethyl orthosilicate (1.15mL) dropwise into the mixed solution prepared in step 1, heat and stir at 60°C for 3h to obtain a milky white suspension, and centrifuge (speed: 8000r / min) to obtain transparent colloid;

[0055] 3. Dry the transparent colloid in a vacuum drying oven at 80°C for 6 hours to obtain a white powder, which is the silicon carbon precursor;

[0056] 4. Mix 0.2g of silicon-carbon precursor with magnesium powder of equal mass, put it into a tube furnace and react at 650°C for 6h under a protective atmosphere of argon to obtain a white powder, wash the powder with hydrochloric acid and then dry it in vacuum for 5h to obtain Porous silicon carbon composites.

[0057] figure 1 In the XRD pattern of the product prepared in this example, an obvious peak of silicon was...

Embodiment 2

[0068] 1. Add 0.6g PEI (Mw=100000) into a mixed solvent composed of 30mL ethanol and 0.5mL water, and stir at room temperature for 1 hour to obtain a mixed solution;

[0069] 2. While stirring, slowly add tetraethyl orthosilicate (1.15mL) dropwise into the mixed solution prepared in step 1, heat and stir at 60°C for 3h to obtain a milky white suspension, and centrifuge (speed: 8000r / min) to obtain transparent colloid;

[0070] 3. Dry the transparent colloid in a vacuum drying oven at 80°C for 6 hours to obtain a white powder, which is the silicon carbon precursor;

[0071] 4. Mix 0.2g of silicon-carbon precursor with magnesium powder of equal mass, put it into a tube furnace and react at 650°C for 6h under a protective atmosphere of argon to obtain a white powder, wash the powder with hydrochloric acid and then dry it in vacuum for 5h to obtain Porous silicon carbon composites.

Embodiment 3

[0073] 1. Add 0.4g PEI (Mw=70000) into a mixed solvent composed of 30mL ethanol and 3mL water, stir at room temperature for 1h to obtain a mixed solution;

[0074] 2. While stirring, slowly add tetraethyl orthosilicate (3mL) dropwise into the mixed solution prepared in step 1, heat and stir at 60°C for 3h to obtain a milky white suspension, and centrifuge (rotating at 8000r / min) to obtain transparent colloid;

[0075] 3. Dry the transparent colloid in a vacuum drying oven at 80°C for 6 hours to obtain a white powder, which is the silicon carbon precursor;

[0076] 4. Mix 0.2g of silicon-carbon precursor with magnesium powder of equal mass, put it into a tube furnace and react at 650°C for 6h under a protective atmosphere of argon to obtain a white powder, wash the powder with hydrochloric acid and then dry it in vacuum for 5h to obtain Porous silicon carbon composites.

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Abstract

The invention discloses a method for preparing a porous silicon-carbon composite material in situ; the method comprises the following steps that (1) a polymer with positive charges is mixed with a solvent to obtain a mixed solution, wherein the main chain or the side group of the polymer with positive charges has an amino group; and the solvent is a mixed solvent composed of an organic solvent andwater; (2) a silicon source is mixed with the mixed solvent obtained in the step (1), the mixture is subjected to hydrolysis reaction to obtain a suspension, and then the suspension is subjected to post-treatment A to obtain a silicon-carbon precursor; and (3) the silicon-carbon precursor is mixed with magnesium powder, magnesium thermal reduction reaction is carried out to obtain a crude product, and post-treatment B is performed to obtain the porous silicon-carbon composite material. The invention discloses the method for preparing the porous silicon-carbon composite material in situ; the prepared porous silicon-carbon composite material is complete in morphology, the particle sizes of the composite material are relatively small, and the particle sizes of the composite material are about 20-60 nm. By taking the porous silicon-carbon composite material as a negative electrode, the cycling stability of the lithium battery can be remarkably improved.

Description

technical field [0001] The invention relates to the field of preparation of silicon-carbon composite materials, in particular to a method for preparing porous silicon-carbon composite materials in situ. Background technique [0002] With the development of today's society, especially the gradual development of new energy vehicles, the demand for high specific energy battery systems is also increasing. Lithium batteries have become the focus of research due to their high energy density, high discharge power, and high rated voltage. In the research of lithium-ion batteries, silicon negative electrodes are currently known to have the largest theoretical specific capacity. 4200mAh), but the silicon negative electrode will have a very large volume expansion (about 400 times) when it is used as a negative electrode charge and discharge cycle, which will cause the silicon negative electrode to fall off from the electrode sheet after many cycles, and the volume of silicon will expan...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62B82Y30/00H01M10/0525
CPCB82Y30/00H01M4/366H01M4/386H01M4/625H01M10/0525Y02E60/10
Inventor 徐刚陈大瑾陶传英韩高荣
Owner ZHEJIANG UNIV
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