Preparation method of silicon/graphene/carbon composite negative electrode material

Abstract

A preparation method of a silicon / graphene / carbon composite negative electrode material comprises the following steps of (1) uniformly dispersing silicon nanoparticles into absolute ethyl alcohol under ultrasonic processing; (2) adding APS by stirring for surface modification of silicon; (3) centrifuging and drying a dispersion liquid to obtain APS-modified silicon nanoparticles, dispersing the APS-modified silicon nanoparticles into the absolute ethyl alcohol to form a dispersion liquid, dropwise adding a graphene solution under stirring, and performing centrifugal washing, freezing and drying; (4) uniformly mixing with polyvinylidene fluoride, coating the mixture on a copper current collector to form a composite material with consistent thickness, and drying the composite material in a vacuum drying box; and (5) performing high-temperature thermal processing in an inert atmosphere. The obtained negative electrode material is high in discharge specific capacity, good in charge-discharge characteristic and relatively high in cycle stability, the process flow is simple, the content of silicon in the material is large, and the preparation method is easy to implement and is suitable for production on a large scale.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a method for preparing a silicon / graphene / carbon composite negative electrode material. Background technique [0002] Lithium-ion batteries have become ideal supporting power sources for portable electronics, mobile products, and electric vehicles due to their high voltage, high specific energy, long cycle life, and environmental friendliness. Due to the development needs of miniaturization, high energy density, and portability of electronic products, especially the development of smart phones and new energy batteries, the energy density of lithium-ion batteries is required to be higher and higher. The improvement of the performance of lithium-ion batteries mainly depends on Due to the improvement of energy density and cycle life of lithium intercalation materials, the current theoretical capacity of lithium-ion batteries using graphite and other materials as negati...

AI Technical Summary

Problems solved by technology

But graphene is not very good at protecting the pulverization of nano-silicon particles

[0005] CN105024076A discloses a lithium-ion battery negative electrode material and its preparation method and application. The material is divided into two layers: a carbon core layer and a silicon coating layer, which can effectively relieve the expansion of the silicon material, thereby improving the cycle performance of the battery material. However, the ability of pure carbon coating to improve the conductivity of composite materials is still limited.

[0006] None of the above-mentioned methods can fundamentally solve the problem of rapid volume expansion of silicon material negative electrode lithium-ion batteries during charging and discharging.

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