Silicon and carbon composite material for lithium ion battery anode and preparation method thereof

Abstract

The invention discloses a silicon and carbon composite material for a lithium ion battery anode and a preparation method thereof. The method comprises following steps: mixing nano silicon, carbon powder and a carbon source by a piece of mixing equipment with a linear speed of 1m / s-50m / s, carrying out heat treatment, wherein the mass ratio of the nano silicon is (0 %, 50 %], the mass ratio of the carbon powder is (0 %, 80 %], the mass ratio of the carbon source is (0 %, 80 %]; crushing and sieving the powder materials after the heat treatment, thus obtaining silicon and carbon composite powder materials; carrying out surface coating to the silicon and carbon composite powder materials by a clad material, wherein the clad material comprises one or the mixture of multiple of the following materials: nano copper oxide, nano magnesium oxide, nano titanium oxide, nano aluminium oxide, nano graphite, graphite flakes or graphene with mass ratio of 1%-10%; carrying out carbon coating treatment to the surface coated silicon and carbon composite powder materials; and carrying out physical magnetism removing treatment to the carbon coated powder materials, thus obtaining the silicon and carbon composite material for the lithium ion battery anode.

Description

technical field [0001] The invention relates to the field of material technology, in particular to a silicon-carbon composite material used for a negative electrode of a lithium-ion battery and a preparation method thereof. Background technique [0002] The energy crisis and environmental problems in contemporary society are becoming more and more prominent, and new clean energy and energy storage have become a hot research topic. In this context, lithium-ion batteries have basically occupied the market of portable consumer electronics due to their high energy density, high power density, long life and environmental friendliness, and are widely used in electric vehicles, large-scale energy storage equipment, decentralized Mobile power and other fields have broad application prospects. [0003] However, with the growth of people's demand, the development of high energy density batteries has become a top priority. At present, the theoretical capacity of the most widely used ...

AI Technical Summary

Problems solved by technology

At present, the theoretical capacity of the most widely used graphite anode material is 372mAh / g, and the measured capacity of high-end graphite materials has reached 365mAh / g, and there is no further breakthrough. Therefore, silicon materials are gradually favored by people

However, the volume expansion of silicon materials reaches 300% when fully intercalating lithium, which will cause a series of problems, which greatly limits its application in the negative electrode of lithium-ion batteries.

In order to overcome this problem, the current mainstream ideas are divided into silicon oxide and silicon carbon composite. Among them, the silicon oxide method is due to the high cost of preparing silicon oxide, and the irreversible reaction with silicon oxide is inevitable when the material is inserted into lithium for the first time. , making it difficult to improve its efficiency in the first week

[0004] For silicon-carbon composite materials, the current mainstream consideration is the core / shell structure (CN102122708A). However, there are too many micropores inside this structure. Although the porous structure is beneficial to the circulation of silicon materials, it may cause material damage in practical applications. No pressure resistance, low compaction density, reducing the volumetric energy density of the battery

In addition, more organic solvents (CN102394288B, CN103367727B, CN102769139B) are used in current reports, which greatly increases the cost of the entire preparation process and has certain potential safety hazards

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