Silicon-based composite material, its preparation method and its application

Abstract

The invention provides a silicon-based composite material, which is prepared from silicon particles, silicate and optional carbon, wherein the mixture of the silicate and the optional carbon forms a massive body, and the silicon particles are dispersed in the massive body. A preparation method comprises the following steps of: dispersing the silicon particles into absolute ethyl alcohol and / or deionized water to form suspension liquid; dispersing the silicate and the optional carbon into the absolute ethyl alcohol and / or the deionized water to form suspension liquid; ultrasonically oscillating the two kinds of suspension liquid respectively, and then stirring; dropwise adding the suspension liquid of the silicon particles into the suspension liquid of the silicate and the optional carbon to form mixed liquid, heating and stirring the mixed liquid until evaporating the mixed liquid into paste; then, putting the paste in an oven to be dried to obtain masses, and grinding and sieving to obtain undersize particles; and conducting heat treatment in an inert atmosphere, and grinding and sieving to obtain the silicon-based composite material. According to the silicon-based composite material, a lattice structure of the silicon particles can be ensured, therefore the activity of the silicon particles is ensured, and the energy density, the first-time coulomb efficiency and the high-temperature storage performance of lithium ion batteries are increased.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a silicon-based composite material, a preparation method thereof, and an application thereof. Background technique [0002] Due to the advantages of high output voltage, large specific energy, small self-discharge, no memory effect, and environmental friendliness, lithium-ion batteries are widely used in various portable electronic devices, and also have great applications in electric vehicles, energy storage equipment and other fields. Good application prospects. [0003] At present, the negative electrode active materials of commercial lithium-ion batteries are usually graphite materials. + Intercalation of graphite interlayers to form LiC 6 compound, when discharged Li + from the graphite layer. The theoretical gram capacity of graphite materials is 372mAh / g. The actual gram capacity of graphite materials currently used has reached 360mAh / g, which is very close to the ...

AI Technical Summary

Problems solved by technology

The expansion and shrinkage of the particles cause the lattice structure of the silicon particles to collapse, the material is granulated and loses its activity, and the expansion of the pole piece will lead to an increase in the gap between the active material particles, a decrease in the conductivity of the pole piece, and an increase in the internal resistance of the battery cell. Deterioration of cycle performance, rate performance, etc.

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