Investigating the structural stability and electronic properties of carbon doped silicon anode for lithium-ion batteries

Silicon is an attractive anode material for lithium-ion batteries due to it having a high theoretical capacity of 4200 mAh/g, however, it experiences severe volume changes during the lithiation and delithiation processes. Doping with carbon can help to mitigate these severe volume changes and increase the electrochemical performance, since carbon forms strong covalent bonds with silicon which are difficult to break as such it acts as a mechanical buffer to accommodate volume expansion hence maintain structural integrity. Furthermore, it forms continuous pathways for electron transport. In this study, the cluster expansion technique was successfully used to generate a silicon carbide (SiC2) structure, which has a hexagonal symmetry and is thermodynamically stable. The density of states and band structure of SiC2 illustrated metallic behaviour, thus promoting conductivity.