Graphene/solid-state electrolyte composite coated silicon composite negative electrode and preparation method thereof

Abstract

The invention discloses a graphene / solid-state electrolyte coated silicon composite material and a preparation method thereof. The preparation method comprises the following steps: coating a silicon-based material with a layer of graphene through a chemical vapor deposition method, and accumulating concentrated ammonia water into an oxide through a precursor ester of an oxide for coating to obtainan oxide and graphene co-coated silicon negative electrode material; performing lithiation on the composite material with lithium hydroxide monohydrate to finally obtain the graphene / solid-state electrolyte coated silicon composite material. In the composite material, graphene directly grows on the surfaces of silicon particles, and the surface of graphene is coated with solid-state electrolyte,thereby forming double-layer coating. The graphene inside can increase the electronic conductivity of the silicon-based material, and relieve volume expansion of silicon. The coating solid-state electrolyte outside can improve the Coulomb efficiency and the magnification performance of the silicon-based negative electrode material, reduce the electrochemical reaction between the negative electrodematerial and electrolyte, increase the Coulomb efficiency of the silicon-based negative electrode and improve the high current charging and discharging performance of the material.

Description

technical field

[0001] The invention relates to the technical field of lithium ion batteries, in particular to a method for coating graphene / solid electrolyte material on the surface of a silicon negative electrode. Background technique

[0002] In recent years, with the rapid development of electric vehicles and mobile electronic equipment markets, it is imminent to study lithium-ion batteries with high energy density, high power density, and long life. Silicon-based materials have become the most promising anode materials for next-generation lithium-ion batteries to replace graphite due to their high theoretical capacity (4200mAh / g), low plateau voltage (0.2V vs. Li / Li+) and abundant resources. However, the commercialization of silicon-based materials also faces some urgent problems, such as short cycle life, low Coulombic efficiency, and poor rate performance. Generally, when the lithium-ion battery is cycled for the first time, the electrolyte and the silicon negative e...

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