Nano silicon material with low cost and high yield and preparation method thereof

Abstract

The invention discloses a nano silicon material with low cost and high yield in the technical field of nano silicon material preparation. Nano-SiO2 with rod-like morphology is directly prepared by using natural attapulgite which is cheap and easily available, and then the nano-SiO2 is reduced by magnesium to acquire single crystal silicon nanoparticles with an average particle diameter of 20 nm. Carbon coating is carried out on the single crystal silicon nanoparticles to acquire the carbon-coated composite nano silicon material which has low cost and is conducive to improving production capacity. A carbon material as a grinding medium is added in ganister sand paste. On the one hand, finer particle grinding can be promoted. On the other hand, traditional dispersants are replaced with the carbon material, which effectively avoids the occurrence of agglomeration between nano-silicon particles. The addition of the carbon material can effectively improve the conductivity of the material, can promote the passivation of the surface of the silicon material, and improves the surface oxidation resistance of the silicon material. The conductivity of the silicon material after carbon coatingtreatment is greatly improved.

Description

technical field [0001] The invention relates to the technical field of nano-silicon material preparation, in particular to a low-cost and high-yield nano-silicon material and a preparation method thereof. Background technique [0002] Compared with the traditional graphite negative electrode lithium battery, the lithium ion battery of silicon negative electrode material has a series of advantages such as large specific capacity, low discharge platform and abundant sources. Silicon is a promising material to replace traditional graphite as lithium ion battery negative electrode, but Silicon material has a large expansion rate during the charging and discharging process, which will lead to the pulverization of silicon particles and the continuous generation and consumption of SEI film, resulting in continuous degradation of performance; as a semiconductor material, its electronic conductivity and ion conductivity are relatively high. Lower, smaller-sized nano-silicon can great...

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Problems solved by technology

[0002] Compared with the traditional graphite negative electrode lithium battery, the lithium ion battery of silicon negative electrode material has a series of advantages such as large specific capacity, low discharge platform and abundant sources. Silicon is a promising material to replace traditional graphite as lithium ion battery negative electrode, but Silicon material has a large expansion rate during the charging and discharging process, which will lead to the pulverization of silicon particles and the continuous generation and consumption of SEI film, resulting in continuous degradation of performance; as a semiconductor material, its electronic conductivity and ion conductivity are relatively high. Lower, smaller-sized nano-silicon can greatly reduce the volume expansion rate during charge and discharge, improve the material's anti-expansion force, and reduce the adverse effects during charge and discharge. Traditional preparation methods can solve the agglomeration phenomenon on the surface of silicon materials , The introduction of excess impurity molecules into the silicon material and the surface acidity and alkalinity of the silicon material cannot be adjusted, resulting in uneven particle size of the silicon material, which greatly reduces the performance of the silicon material and reduces the service life of the silicon material. While the performance is poor, the cost of silicon material preparation increases, so we propose a low-cost and high-yield nano-silicon material and its preparation method