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Preparation method of lithium ion battery silicon-carbon composite negative electrode material based on magnesiothermic reduction

A silicon-carbon composite material and a technology for lithium-ion batteries, which are applied in the field of preparation of lithium-ion battery materials, can solve the problems of inability to obtain electrical conductivity, poor electrical conductivity, and influence on electrochemical capacity.

Pending Publication Date: 2020-10-27
NANJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this invention directly uses silicon nanoparticles, and uses the dispersion method of ultrasonic dispersion and magnetic stirring, which can play a role in dispersion when S1. The dispersed silicon nanoparticles will reunite together, resulting in the aggregation and accumulation of silicon in the final product, affecting its electrochemical capacity; using polyacrylonitrile solution, the stable carbon structure cannot be maintained after high temperature treatment, and carbonized acrylonitrile is sintered at 1000 °C , unable to obtain higher conductivity of carbon, resulting in poor conductivity of silicon-carbon conforming materials

Method used

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  • Preparation method of lithium ion battery silicon-carbon composite negative electrode material based on magnesiothermic reduction

Examples

Experimental program
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Effect test

Embodiment 1

[0026] (1) The preparation of graphite dispersion liquid: add 75g water to obtain solution in the carboxymethylcellulose (CMC) solution of 0.5wt% in 10g mass concentration, stir solution and add 55g natural graphite, graphite particle diameter is 15um, stirs evenly Obtaining a graphite dispersion with a solid content of 45-55%;

[0027] (2) Preparation of graphite / silicon dioxide composite: 20g30wt% silica sol (Shandong Baite New Material Co., Ltd., silica particle diameter is 50nm) is stirred and dropped into the above-mentioned graphite dispersion liquid, and the dispersion system is adjusted. The solid content reaches 40-50%, spray drying (Okawahara spray dryer), under the protection of argon, put the dried product in a tube furnace, take 200min to heat up from room temperature to 800°C and keep it warm for 2h, then naturally cool to room temperature , to obtain a graphite / silica composite;

[0028](3) Magnesia thermal reduction reaction: 1g of graphite / silicon dioxide com...

Embodiment 2

[0040] (1) The preparation of graphite dispersion liquid: add 75g water to obtain solution in the hydroxypropyl cellulose (HPC) solution of 1wt% in 9g mass concentration, stir solution and add 60g artificial graphite, graphite particle diameter is 20um, stirs to obtain Graphite dispersion with a solid content of 45-55%;

[0041] (2) Preparation of graphite / silica composite: 15g, 20wt% silica sol (Shandong Baite New Material Co., Ltd., silica particle size is 50nm) was stirred and dropped into the above-mentioned graphite dispersion liquid to adjust the dispersion The solid content of the system reaches 40-50%, spray drying (Okawahara spray dryer), under the protection of argon, put the dried product in a tube furnace, take 200min to heat up from room temperature to 800°C and keep it warm for 2h, then cool naturally To room temperature, obtain graphite / silicon dioxide composite;

[0042] (3) Magnesia thermal reduction reaction: 1g of graphite / silicon dioxide composite is groun...

Embodiment 3

[0047] (1) Preparation of graphite dispersion: adding 75g water to obtain solution in 15g mass concentration of 2wt% hydroxypropyl cellulose (HPC) solution, stirring the solution and adding 55g natural graphite, graphite particle size is 25um, stirred evenly to obtain Graphite dispersion with a solid content of 45-55%;

[0048] (2) Preparation of graphite / silica composite: 20g of 40wt% silica sol (Shandong Baite New Material Co., Ltd., silica particle size is 50nm) was stirred and dropped into the above-mentioned graphite dispersion, and the dispersion system was adjusted The solid content reaches 40-50%, spray drying (Okawahara spray dryer), under the protection of argon, put the dried product in a tube furnace, heat up from room temperature to 800°C with 200min and keep it warm for 2h, and cool naturally to At room temperature, a graphite / silicon dioxide composite is obtained;

[0049] (3) Magnesia thermal reduction reaction: 1g of graphite / silicon dioxide composite is grou...

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Abstract

The invention relates to a preparation method of a lithium ion battery silicon-carbon composite negative electrode material based on magnesiothermic reduction. The method comprises the following steps: preparing a high-concentration graphite dispersion solution from graphite and a carboxymethyl cellulose (CMC) or hydroxypropyl cellulose (HPC) solution; adding nano silicon dioxide sol into the graphite dispersion solution to uniformly disperse the nano silicon dioxide sol, carrying out spray drying on the dispersion solution to form a graphite / silicon dioxide compound, carrying out a magnesiothermic reduction reaction, finally adding styrene-acrylonitrile copolymer emulsion, and carrying out high-temperature treatment to obtain the lithium ion battery silicon-carbon composite material. Thelithium ion battery silicon-carbon composite material prepared by the method is good in conductivity, high in dispersion degree of graphite and silicon, high in battery capacity and long in cycle life.

Description

technical field [0001] The invention belongs to a preparation method of a lithium ion battery material, and relates to a preparation method of a lithium ion battery silicon-carbon composite material based on magnesia thermal reduction. Background technique [0002] The theoretical capacity of pure silicon as a lithium-ion battery anode material is 4200mAh / g, and silicon and carbon are usually combined to form a silicon-based material. Because of its high theoretical capacity, it is expected to become the next-generation widely used lithium-ion battery anode material, but Its disadvantages are also obvious. Since silicon undergoes serious volume expansion and contraction during the lithium intercalation and de-cycling process, the material structure is destroyed and pulverized, which leads to the degradation of electrode cycle performance. [0003] In order to solve the problem that silicon anode materials are prone to stress cracking during charge and discharge, resulting in...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525B82Y30/00
CPCH01M4/366H01M4/386H01M4/625H01M10/0525B82Y30/00Y02E60/10
Inventor 刘祥黄楚娟汪舟鹭史颢王金培刘丽
Owner NANJING UNIV OF TECH
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