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Preparation method for silicon carbon composite material for lithium ion battery negative electrode

A technology for lithium ion batteries and composite materials, which is applied in the field of preparation of silicon carbon-based composite materials for lithium ion battery negative electrodes, can solve the problems of insignificant relief of expansion effect, decreased cycle performance, detachment of active materials, etc., and achieves prevention of agglomeration effect, Stable and evenly distributed effect

Active Publication Date: 2012-12-19
SOUTH CHINA UNIV OF TECH
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there are two fatal shortcomings in silicon-based negative electrode materials: one is that silicon crystals have a crystal structure similar to diamond, which will produce a huge volume change (>300%) during the process of lithium intercalation-delithiation, which will lead to electrode materials During the cycle process, the active material is gradually pulverized, and the active material is separated from the current collector, resulting in a decrease in cycle performance; second, because silicon is a semiconductor, coupled with the phase transition during the charge and discharge process, the irreversible capacity is large, and the charge and discharge efficiency is low.
The system expansion effect of the silicon-metal system is not alleviated obviously, and the capacity retention rate is poor

Method used

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  • Preparation method for silicon carbon composite material for lithium ion battery negative electrode
  • Preparation method for silicon carbon composite material for lithium ion battery negative electrode
  • Preparation method for silicon carbon composite material for lithium ion battery negative electrode

Examples

Experimental program
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Effect test

Embodiment 1

[0032] The preparation method of the silicon-carbon-based composite material for the lithium-ion battery negative electrode of the present embodiment is as follows:

[0033] The first step of ball milling: add anhydrous ethanol grinding aid with a mass of 2% of the mass of the elemental silicon to the elemental silicon, and use dielectric barrier discharge plasma-assisted high-energy ball milling method for ball milling, wherein the mass ratio of grinding balls to elemental silicon is 30:1 , the milling time is 10h;

[0034] The second step of ball milling: mix the silicon powder and carbon raw material powder obtained in the first step of ball milling, wherein the mass ratio of silicon powder and carbon raw material is 1:4, add anhydrous ethanol with a mass of 2% of the total mass of the abrasive, and use a medium Barrier discharge plasma-assisted high-energy ball milling method ball milling, wherein the ratio of balls to the total mass of silicon powder and carbon raw materi...

Embodiment 2

[0043] The preparation method of the silicon-carbon-based composite material for the lithium-ion battery negative electrode in this embodiment is the same as that in Embodiment 1, except that the ball milling time in the second step of ball milling is 10 h.

[0044] The test results show that the composite material Si prepared in this embodiment 20 C 80The first reversible capacity is 953.2mAh / g. The discharge capacity remained at 582.9mAh / g after 85 cycles.

Embodiment 3

[0046] The preparation method of the silicon-carbon-based composite material for lithium ion battery negative electrode of the present embodiment, except that the quality of the grinding aid of the first step ball milling is 1% of the mass of elemental silicon; the quality of the grinding aid of the second step ball milling is mixed silicon powder and 1% of the total mass of the carbon raw material powder, and the ratio of the mass of the grinding ball to the total mass of the silicon powder and the carbon raw material powder is 70:1, and the rest are the same as in Example 1.

[0047] The test results show that the composite material Si prepared in this embodiment 20 C 80 The initial reversible capacity is 938.4mAh / g, and the discharge capacity remains at 432.8mAh / g after 85 cycles.

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Abstract

The invention discloses a preparation method for a silicon carbon composite material for a lithium ion battery negative electrode. The method comprises the following steps: primary ball milling: a step of adding a grinding aid into elementary silicon for ball milling; and secondary ball milling: a step of mixing silicon powder obtained after primary ball milling with carbon powder and adding a grinding aid for ball milling again. The mass content of the carbon powder is 20 to 80%. A discharge gas medium employed in the dielectric barrier discharge plasma assisted high-energy ball milling method is inert gas. According to the invention, silicon in the composite material prepared in the invention can be finely and uniformly distributed on a carbon matrix, effective refining of silicon can be carried out on the basis that the integrity of graphite sheets is ensured, reversible capacity of a battery is improved, the problems of volume expansion and poor conductivity of a silicon-based electrode are alleviated, and comprehensive performance of the lithium ion battery is improved.

Description

technical field [0001] The invention relates to lithium-ion battery technology, in particular to a method for preparing a silicon-carbon-based composite material for a negative electrode of a lithium-ion battery. Background technique [0002] Compared with other secondary batteries, lithium-ion batteries have the advantages of high energy density, long cycle life, and high working voltage. This makes it widely used in people's lives, and has become an ideal power source for various portable electronic devices. The performance of a lithium-ion battery is mainly determined by its internal electrode materials. Carbon materials are currently commercialized lithium-ion battery anode materials because they have the advantages of stable discharge platform, good charge and discharge reversibility, and low cost. However, carbon anode materials such as graphite also have low theoretical specific capacity (372mAh / g), poor safety performance and large irreversible capacity for the fi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/38H01M4/583
CPCY02E60/12Y02E60/10
Inventor 朱敏陈宇龙胡仁宗刘辉曾美琴
Owner SOUTH CHINA UNIV OF TECH
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