A kind of silicon carbon negative electrode material and preparation method thereof

Abstract

The invention discloses a silicon-carbon negative electrode material and a preparation method thereof, which sequentially include: silicon / silicon oxide particles, N-3-(trimethoxysilyl) propyl vinyl diamine molecular layer, and carbon nanotubes from the inside to the outside. Conductive layer, polydopamine carbonized layer, the silicon / silicon oxygen particles are polyvalent oxides of silicon or silicon or a mixture thereof, the N-3-(trimethoxysilyl) propyl vinyl diamine molecular layer, The thickness is 1-10 μm; the polydopamine macromolecule in the polydopamine carbon layer uniformly forms a film on the outermost layer to cover silicon / silicon oxide particles and carbon nanotubes, and the film thickness is 0.01-3 μm. The synergistic effect of the three-layer structure and silicon / silicon oxide particles can significantly improve the structural stability and conductivity of silicon-based anode materials, and further improve the rate performance and cycle performance. The preparation method of the invention combines molecular self-assembly technology and in-situ polymerization technology and is applied to the field of negative electrode materials of lithium ion batteries, and has simple process, convenient operation and short preparation period.

Description

technical field [0001] The invention relates to a silicon-carbon negative electrode material and a preparation method thereof. Background technique [0002] With the vigorous development of my country's new energy industry, lithium-ion batteries have become the first choice for battery systems for electric vehicles and large-scale energy storage equipment. At present, graphite-based carbon-based anode materials widely used in lithium-ion batteries have low capacity and cannot meet the requirements of high-performance lithium-ion battery anodes. The theoretical capacity of silicon material is as high as 4200mAh / g, the potential of lithium ion extraction is low, the platform discharge is stable and long, the safety performance is high, and the environment is friendly and pollution-free. These advantages make it attract great attention and are considered to be the most commercial in the market It is the preferred alternative material for carbon anode materials with promising a...

AI Technical Summary

Problems solved by technology

However, for the first time, silicon-based anode materials have high irreversible capacity, poor stability, and huge volume expansion, which reduces electrical conductivity and cycle life.

The published Chinese patent document CN106711431A coats the surface-treated silicon powder with polydopamine as a battery negative electrode material to improve the structure and cycle stability, but the polydopamine in this invention is in a high molecular state without carbonization, so the conductivity Poor, will increase internal resistance, lack of stable conductive network