Si/C nano composite anode material as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a Si / C nano composite anode material. The method comprises the following steps of adding phenolic resin, which serves as a carbon source, into acetone,stirring continuously until turning milk white, then adding silicon nano particles into mixed emulsion, enabling an obtained mixed solution to be subjected to ultrasound, afterwards stirring for 24h continuously, drying the solution by distillation, extracting and drying in vacuum at 60 DEG C to obtain a Si / C nano composite precursor; performing pyrolysis on the Si / C nano composite precursor in aninert atmosphere, wherein the pyrolysis temperature is 800-1,000 DEG C and the pyrolysis time is 4-5h, cooling to room temperature, then grinding pyrolysis products to a micro order to obtain the Si / C nano composite anode material. The phenolic resin is adopted as the carbon source to combine with an ultrasonic method to prepare nano silicon-containing porous carbon, the pores of carbon and abundant spaces between carbon layers provide more interfaces for reaction between the carbon and lithium ions, so that the electrochemical property of silicon is greatly improved, the declination of capacity is reduced, by tests, the specific capacity is up to 880mAhg-1, the electric current density is 100mAg-1, and the Si / C nano composite anode material still has capacity retention ratio after circulating 500 times.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a Si / C nanocomposite anode material and a preparation method and application thereof. Background technique [0002] The development of lithium-ion batteries has been receiving much attention, but the existing graphene materials on the market as battery electrodes have very limited capacity (the capacity is about 370mAh / g at a current density of 100mA / g). Many precursors with modified structures have been investigated to improve the performance of anode materials, and silicon-based polymer ceramic (PDC) materials are a good candidate (theoretical capacitance is around 4000mAh / g). However, the silicon-based electrode will expand in volume during the charge and discharge process, causing its surface to break and its volume to decrease rapidly. This limits the wide application of silicon-based cathode materials. Using double-doped graphene (NSGs) can effec...

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Problems solved by technology

But these methods can lead to agglomeration of the treated graphene and reduce its performance

[0003] Due to the complex synthesis method and high synthesis cost of the silicon electrode material synthesized by the existing method, it is not conducive to large-scale production, and the volume change will occur during the charging and discharging process, which will reduce the capacitance density.

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