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A kind of graphite/silicon/carbon composite negative electrode material and preparation method thereof

A negative electrode material, carbon composite technology, applied in negative electrodes, battery electrodes, active material electrodes, etc., can solve the problems of uneven distribution, low cycle stability of materials, easy agglomeration, etc., to improve distribution uniformity and improve cycle stability. The effect of improving the uniformity of dispersion

Active Publication Date: 2022-02-15
WANXIANG 123 CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The present invention aims to overcome the disadvantages of easy agglomeration, uneven distribution, and low cycle stability of materials in the prior art when silicon is coated, and provides a graphite / silicon / carbon composite negative electrode material and its preparation method. Silicon coating is not easy to agglomerate And uniform distribution, high material cycle stability

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  • A kind of graphite/silicon/carbon composite negative electrode material and preparation method thereof

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Effect test

Embodiment 1

[0030] A preparation method of graphite / silicon / carbon composite negative electrode material, comprising the steps of:

[0031] (1) Take 4.5g of graphite and disperse it into the sulfuric acid and nitric acid mixed solution with a volume ratio of 3:1, stir at room temperature for 24h after ultrasonication for 3h, wash, and remove the acid solution;

[0032] (2) Weigh 0.25 g of silicon dioxide and disperse it into 100 ml of pure water, add 0.5 g of 3-aminopropyltriethoxysilane, stir at room temperature for 5 hours, and wash to obtain surface amino-modified silicon dioxide;

[0033] (3) Disperse the graphite obtained in step (1) and the silica obtained in step (2) in a pure water / ethanol system, add hydrochloric acid, control the acid concentration to 0.5mol / L, stir for 24 hours, and add an appropriate amount of asphalt (According to the amount of residual carbon, ensure that the carbon content in the final prepared material is 10%), continue to stir for 24h, wash and dry to obt...

Embodiment 2

[0035] A preparation method of graphite / silicon / carbon composite negative electrode material, comprising the steps of:

[0036] (1) Take 4g of graphite and disperse it into the sulfuric acid and nitric acid mixed solution with a volume ratio of 3:1, stir at room temperature for 24h after ultrasonication for 3h, wash, and remove the acid solution;

[0037] (2) Weigh 0.5 g of silicon dioxide and disperse it into 100 ml of pure water, add 1 g of 3-aminopropyltrimethoxysilane, stir at room temperature for 5 hours, and wash to obtain surface amino-modified silicon dioxide;

[0038] (3) Disperse the graphite obtained in step (1) and the silica obtained in step (2) in a pure water / ethanol system, add hydrochloric acid, control the acid concentration to 0.5mol / L, stir for 12 hours, and add an appropriate amount of asphalt (According to the residual carbon content, ensure that the carbon content in the final prepared material is 10%), continue to stir for 12 hours, wash and dry to obta...

Embodiment 3

[0041] A preparation method of graphite / silicon / carbon composite negative electrode material, comprising the steps of:

[0042] (1) Take 4.5g of graphite and disperse it into the sulfuric acid and nitric acid mixed solution with a volume ratio of 3:1, stir at room temperature for 24h after ultrasonication for 3h, wash, and remove the acid solution;

[0043] (2) Weigh 0.25 g of silicon dioxide and disperse it into 100 ml of pure water, add 0.5 g of 3-aminopropyltriethoxysilane, stir at room temperature for 5 hours, and wash to obtain surface amino-modified silicon dioxide;

[0044] (3) Disperse the graphite obtained in step (1) and the silicon dioxide obtained in step (2) in pure water, add hydrochloric acid, control the acid concentration to 0.5mol / L, stir for 24h, add an appropriate amount of dopamine (according to residual carbon content, to ensure that the carbon content in the final prepared material is 10%), continue to stir for 24h, wash and dry to obtain graphite / silico...

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Abstract

The present invention relates to the field of negative electrode materials for lithium ion batteries, in particular to a graphite / silicon / carbon composite negative electrode material and a preparation method thereof, comprising the following steps: (1) pretreatment of graphite; (2) pretreatment of silicon dioxide; 3) Mix the two to make silica evenly adsorbed on the graphite surface, and the outer layer is coated with carbon source to obtain graphite / silicon dioxide / carbon composite material; (4) Perform magnesia thermal reduction to obtain graphite / silicon / carbon composite negative electrode Material. The present invention combines graphite and silicon dioxide by electrostatic adsorption, improves the uniformity of silicon dioxide dispersion on the graphite surface, improves the distribution uniformity of silicon on the graphite surface after magnesia thermal reduction, and reduces the expansion stress of silicon , improve the cycle stability and prolong the service life; at the same time, there is a buffer space between the graphite and the carbon that can accommodate the volume expansion of silicon, which further improves the cycle stability of the present invention and prolongs the service life.

Description

technical field [0001] The invention relates to the field of negative electrode materials for lithium ion batteries, in particular to a graphite / silicon / carbon composite negative electrode material and a preparation method thereof. Background technique [0002] The negative electrode material of lithium-ion batteries is one of the key factors restricting the performance of lithium-ion batteries in all aspects. The current commercial negative electrode graphite material has a theoretical specific capacity of only 372mAh / g, which cannot meet the requirements of high energy density power batteries. The theoretical lithium intercalation capacity of silicon material is as high as 3579mAh / g at room temperature, and it has abundant reserves and low price. It is a very potential negative electrode material for lithium-ion batteries. However, its huge volume effect and semiconductor characteristics make the cycle performance and rate of the battery poor, which limits its application....

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M4/62H01M10/0525
CPCH01M4/366H01M4/386H01M4/587H01M4/625H01M4/628H01M10/0525H01M2004/021H01M2004/027Y02E60/10
Inventor 朱丹凤苏敏李慧
Owner WANXIANG 123 CO LTD
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