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

Abstract

The invention provides a silicon-carbon composite negative electrode material. According to the negative electrode material, lithium acetate is coated on the surface of the silicon-carbon composite material, wherein the lithium acetate has properties similar to SEI film so that the consumption of lithium ions is reduced in the charging and discharging process and the first efficiency of the silicon-carbon composite material is improved; meanwhile, the lithium acetate coated on the surface has the characteristic of high lithium ion content, which makes it provide sufficient lithium ions in thecharging and discharging process and improves the magnification and cycle performance of the material. The inner core of the silicon-carbon composite negative electrode material uses a silane couplingagent to react with a silane compound to form a crosslinked polymer to obtain a silicon oxide compound with a stable network structure. besides, titanium dioxide is doped in the silicon oxide compound and the conductivity and the safety performance of the material can be enhanced by relying on the high conductivity and high voltage platform characteristics of titanium dioxide; meanwhile, the conductive agent with large specific surface area and high conductivity is utilized to further improve the conductivity of the silicon-carbon material.

Description

technical field [0001] The invention belongs to the field of lithium ion battery materials, and in particular relates to a silicon-carbon composite negative electrode material and a preparation method thereof. Background technique [0002] With the increasing demand for lithium-ion batteries with high specific energy density in the market, the market requires lithium-ion battery anode materials to have high specific capacity and cycle performance, and currently the lithium-ion battery anodes on the market mostly use graphite as raw material, but graphite The theoretical capacity of the battery is only 372mAh / g, which has been difficult to meet the higher requirements of the market for negative electrodes. Silicon materials have attracted unanimous attention from researchers because of their advantages of up to 4200mAh / g theoretical capacity, low off-potential and abundant storage capacity. However, during the charging and discharging process, silicon produces a huge volume ...

AI Technical Summary

Problems solved by technology

However, the various problems of silicon anodes have not been systematically resolved, especially the problem of low efficiency for the first time.

However, the electrical conductivity of the material has not been improved and the increase in the first efficiency is not obvious. The reason is that the LiF film in the inner shell is an inorganic film and has a general compatibility with the organic electrolyte, which cannot achieve good cycle performance.

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