Inlaying Silicon in SiC-Derived Graphite with Unique Cavity Structure as a High-Capacity Anode for Li-Ion Batteries

Abstract

Silicon-based anode in Li-ion batteries has received much attention due to its extremely high theoretical capacity which can support high-energy-density battery system. However it suffers seemingly insurmountable barriers including volume expansion and capacity fading during repetitive cycling. In this work, we demonstrated a new kind of silicon/carbon (Si/C) composite design to address the issues in the silicon-based anode application via building a three-dimensional structure of nano Si and carbide-derived-graphite (CDG). Unique cavity-structured CDG made from SiC powder via scalable high temperature treatment, could supply a conductive host for the well-dispersed nano Si particles. CDG/Si composite get improved cycle stability and maintained high capacity of 637 mAh g−1 after 500 cycles. Rate performance of CDG/Si was also enhanced, which should be attributed to good electrolyte accessibility and short ion diffusion distance of CDG to enhance electrode kinetics. In addition, CDG was verified to accommodate higher content of Si of 60%, to achieve higher capacity of 1800 mAh g−1. This work provided a good alternative of carbon matrix for Si/C anode, and it is anticipated that this kind of carbide derived graphite might be of great interest to the further development of high-capacity Si-based anode in Li-ion batteries.