Hierarchical micro & mesoporous silicon carbide flakes for high-performance electrochemical capacitive energy storage

Hierarchical micro/mesoporous silicon carbide flakes (SiCF) with a high surface area of about 1376 m² g^-1 are obtained by one-step carbonization of waste Si wafer without any chemical or physical activation. The micropores are derived from the partial evaporation of Si atoms during the carbonization process and mesopores are formed by the integration of neighboring micropores. During carbonization process, the proportion of micro and mesopores in SiCF can be controlled by carbonization time by controlling the amount of partial evaporation of Si atoms. The SiCF electrode carbonized for 8 h at 1250°C exhibits high charge storage capacity with a specific capacitance of 203.7 F g^-1 at a scan rate of 5 mV s^-1 with 87.3% rate performance from 5 to 500 mV s^-1 in 1 M KCl aqueous electrolyte. The outstanding electrochemical performance can be the synergistic effect of both enhanced electric double layer properties caused by micropores and reduced resistant pathways for ions diffusion in the pores as well as a large accessible surface area for ion transport/charge storage caused by mesopores. These encouraging results demonstrate that the SiCF carbonized for 8 h at 1250°C can be promising candidate for high performance electrode materials for supercapacitors.