Constructing Si/6H-SiC Heterostructure As a High-Performance Anode for Boosting Lithium-Ion Storage.

Abstract

Silicon (Si) anodes offer significant potential due to their high capacity. However, their drastic volume change limits their utility, resulting in a shorter cycling life. In this paper, microsilicon particles and 6H-SiC particles were ball-milled and subsequently coated a layer of amorphous carbon, yielding Si/SiC@C composites. Computational and experimental results reveal that this heterostructure formed between Si and 6H-SiC enhances the electronic conductivity of the Si/SiC@C composites dramatically, as well as the Li ion diffusion rate. Thereby, the Si/6H-SiC heterostructure increases capacity and enhances the rate capability of the Si-based anode. Significantly, the conductivity of Si/SiC@C composites surpasses that of Si@C composites by a factor of around 330. Furthermore, tough, evenly distributed, and electrochemically inert 6H-SiC serves as a rigid framework. By reducing the expansion rate of Si-based anodes and mitigating mechanical stress during cycles, this improves the cycling stability. Additionally, the Si/SiC@C anodes demonstrate superior cycle performance (814.6 mAh g-1 at 1 A g-1 after 400 cycles with capacity retention of 88.0%) and excellent rate capability (762 mAh g-1 at 5 A g-1).