Silicon/silicon oxycarbide/graphite composite negative electrode material

Abstract

The invention relates to a silicon / silicon oxycarbide / graphite composite negative electrode material which is a silicon-containing material which has the size being lower than 3 microns uniformly and is firmly distributed on the surface of a negative electrode of graphite. The invention further provides a preparation method of the composite negative electrode material. The preparation method comprises the steps of dispersing a silicon-containing material in a liquid organo-siloxane monomer, sequentially adding an acid liquid of alcohol and water, a curing agent and a graphite negative electrode material, then carrying out ball milling or mechanical stirring, pinching and mixing to obtain a paste-type mixture; calcining the paste-type mixture at high temperature under a protective atmosphere, crushing and sieving to obtain different-particle-size silicon / silicon oxycarbide / graphite lithium-ion battery negative electrode material. The silicon-containing materials of the silicon / silicon-oxygen carbon / graphite composite negative electrode material are firmly and uniformly distributed on the surface of a graphite material; due to the structure, the silicon-containing materials can be effectively adsorbed on the surface of the graphite, the self agglomeration of the silicon-containing material can be avoided and the silicon-containing material is prevented from peeling off from the graphite; the silicon / silicon oxycarbide / graphite composite negative electrode material has the characteristics that the charge and discharge specific capacities are adjustable, and the electrochemical cycle stability is high.

Description

technical field [0001] The invention relates to a highly dispersed silicon / silicon carbon / graphite composite negative electrode material for lithium ion batteries and a preparation method thereof. technical background: [0002] Due to its performance advantages, lithium-ion batteries have been used in various mobile energy storage, such as laptops, mobile phones and cameras. With the development of lithium-ion batteries, high specific energy, long-life, and low-cost lithium-ion batteries that can be used in the fields of electric vehicles and energy storage power stations will become the focus of research. Currently, as one of the main factors determining battery performance, positive electrode materials, such as lithium manganese oxide (LiMn 2 o 4 ), lithium cobaltate (LiCoO 2 ), lithium iron phosphate (LiFePO 4 ) and ternary materials, a major breakthrough has been made in technology, which has laid the foundation for the research and development of high-performance li...

AI Technical Summary

Problems solved by technology

[0005] There are two main methods to improve silicon negative electrode materials: one is the nanometerization of the material size. By reducing the particle size, the tension generated by the volume expansion can be easily released, so as to prevent particle breakage and shorten the lithium ion (Li + ) transmission distance, to speed up the transmission speed; however, pure silicon nanoparticles have high surface energy and defects, their thermodynamic properties are unstable, and they are easy to agglomerate in the process of charging and discharging, resulting in rapid decay of battery capacity

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