A carbon-silicon composite material and its preparation method and application

Abstract

The embodiment of the present invention discloses a method for preparing a carbon-silicon composite material. By uniformly dispersing hydrocarbyl borane, nano-scale silicon powder and graphene, performing a hydrothermal reaction at 100-200°C, drying the product, and using NH3 and inert The mixed gas of the gas carbonizes the hydrothermal reaction product, and then passes through the conductive polymer monomer supported by the inert gas to react. The composite material has a core-shell structure, the inner core is an aggregation molding of nano-scale silicon powder, the inner core is doped with B elements, and the outer shell is doped with N and B elements. The core nano-scale silicon powder of the present invention is doped with boron by hydrothermal method to form a porous structure, which can reduce the expansion of silicon in the process of charging and discharging. Specific capacity and electronic conductivity, the shell layer is doped with a certain amount of boron and nitrogen elements, which is beneficial to the improvement of the specific capacity and the reduction of the impedance of the composite material.

Description

A kind of carbon-silicon composite material and its preparation method and application technical field [0001] The invention belongs to the field of lithium ion batteries, in particular to a carbon-silicon composite material and a preparation method and application thereof. Background technique Silicon carbon material has become the preferred material for high energy density negative electrode material due to its high energy density and wide sources. However, due to the high expansion of the silicon carbon material itself, some even as high as 200%, and the poor electrical conductivity, it affects the Its fast charging and low temperature performance limit its application. Under the same positive electrode material, namely under the same condition of N / P, improve the specific capacity of negative electrode material, on the one hand, can Reduce the areal density of the negative pole piece to improve its fast charging performance. On the other hand, less silicon carbon ...

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Problems solved by technology

[0004] In the prior art, silicon-carbon materials are modified by doping different elements, but this kind of doping is generally completed by simple mixing with silicon-carbon materials, the consistency of the materials is poor, and the performance improvement is limited

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