Silicon negative electrode material with fluff structure and preparation method of silicon negative electrode material

Abstract

The invention discloses a silicon negative electrode material with a fluff structure and a preparation method of the silicon negative electrode material. The silicon negative electrode material with the fluff structure comprises a silicon-based active material, carbon nanotubes, a carbon layer and a fast ion conductor layer, wherein the carbon nanotubes grow on the surface of the silicon-based active material in situ to form a fluff structure, the surfaces of the silicon-based active material and the carbon nanotubes are coated with the carbon layer, the surface of the carbon layer is coated with the fast ion conductor layer, the carbon layer grows in the axial direction of the carbon nanotubes, and it is ensured that the material still has the fluff structure finally. According to the invention, through the fluff structure on the surface thereof, more conductive channels are provided; reliable conductive contact of the silicon material before and after volume expansion is guaranteed,so that volume expansion is buffered better, cracking of a coated film is avoided, ionic conductivity can be improved greatly by controlling graphitization degree of the carbon nanotubes and matchingwith the fast ion conductor layer, and the material has the characteristics of high conductivity, long cycle, high rate and the like.

Description

technical field [0001] The invention belongs to the technical field of batteries, and in particular relates to a silicon negative electrode material with a fluffy structure and a preparation method thereof. Background technique [0002] Due to its high theoretical specific capacity (4200 mA h / g at high temperature and 3580 mA h / g at room temperature), low delithiation potential (<0.5 V), silicon anode material is environmentally friendly, abundant in reserves, and low in cost. It is considered to be a very potential next-generation high-energy-density lithium-ion battery anode material, but its volume expansion and unstable interface reactions during charging and discharging have not been completely resolved, which greatly limits the development of silicon materials. . At present, the research directions of silicon anode materials mainly include nano-silicon-carbon composite materials, silicon oxide materials, amorphous silicon alloys, porous silicon-oxygen materials, et...

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Problems solved by technology

However, it has been proved by literature that in the long cycle process, the coating film will still be cracked due to excessive volume expansion, resulting in reduced electrical contact and poor electrical conductivity.

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