A kind of steric buffer, silicon oxide composite material doped with lithium and its preparation method, lithium ion battery

Abstract

A space buffer lithium-doped silicon oxide composite material and a preparation method therefor, and a lithium-ion battery, relating to the technical field of lithium-ion batteries. The material is a core-shell structure. The core is a lithium-predoped silicon oxide composite material, and the shell is a coating carbon layer. The lithium doping is implemented by converting silicon oxide in the silicon oxide composite material into lithium silicate by means of solid phase reaction during the preparation process. The method for preparing a space buffer lithium-doped silicon oxide composite material comprises: after silicon oxide particle surfaces are coated with a lithium source, a coating carbon layer is formed on the obtained particle surfaces by means of chemical vapor carbon deposition; the obtained coated material is sintered in vacuum or inert atmosphere; the lithium source with which the surfaces are coated reacts with silicon oxide. On one hand, the lithium doping of the silicon oxide material is implemented; on the other hand, the formation of a cavity structure is implemented. The space buffer lithium-doped silicon oxide composite material has the characteristics of high specific capacity, high first-time charging and discharging efficiency, and long service life.

Description

technical field [0001] The invention relates to a space-buffering, lithium-doped silicon oxide composite material, a preparation method thereof, and a lithium-ion battery, belonging to the technical field of lithium-ion batteries. Background technique [0002] With the increasing application range of lithium-ion batteries in different fields, people put forward higher requirements for the performance of lithium-ion batteries. In particular, many application fields have higher and higher requirements for the energy density of lithium-ion batteries. Whether it is 3C products or electric vehicles, people expect the energy density of batteries to reach a new order of magnitude, making the battery life or The cruising range is no longer the main factor that plagues the product. However, it is becoming more and more difficult to increase the energy density of current lithium-ion batteries, and energy density has become the biggest bottleneck restricting the development of current...

AI Technical Summary

Problems solved by technology

However, silicon oxide materials are currently facing two problems: the first is the high volume expansion during the lithiation process, which can reach 200%; the high volume expansion will inevitably lead to material failure, interface degradation and cycle performance decline.

This method solves the defects of high expansion and low first effect of silicon oxide from the material scale, but the lack of internal buffer structure makes the material still face the problems of interface instability and poor circulation in the process of volume expansion and contraction

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