Influence of surface oxygen functional group on the electrochemical behavior of porous silicon carbide based supercapacitor electrode

Supercapacitors have been attracting considerable interest because of their wide range of applications in electric vehicles, digital devices due to their high power density, short charging time, and long cycling life. For ideal charge/discharge mechanism, the micro and mesoporous silicon carbide flakes (PSF) with a high surface area of 1376 m² g^-1 were obtained by one-step carbonization of Si flakes. The micropores originated from the partial evaporation of Si atoms during the carbonization process, while the mesopores were formed by the integration of neighboring micropores. Subsequently, oxygen-containing functional groups were introduced on the PSF surface to stimulate the faradic redox reaction during the charge/discharge process. The PSF electrode oxidized for 24 h (OPSF-24 h) exhibits a high charge storage capacity, showing a specific capacitance of 243.3 F g^-1 at a scan rate of 5 mV s^-1 with 85.6% rate performance from 5 to 500 mV s^-1 in 1 M KCl aqueous electrolyte. This outstanding capacitive performance of OPSF-24 h electrode can be attributed to the harmonious synergistic effect between the electric double-layer capacitive contribution of the PSF and the pseudocapacitive contribution of the oxygen-containing functional groups.