Porous silicon carbide flakes derived from waste silicon wafer for electrochemical supercapacitor

• Porous SiC flakes are derived by waste Si wafer via carbonization process.
• Micropores are derived by partial evaporation of Si atoms during the carbonization.
• Mesopores are formed by the integration of neighboring micropores.
• The material has specific capacitance of 49.2 F g−1 in 1 M KCl electrolyte.
• The material shows energy density of 65.84 W h kg−1 in 1 M BMIM BF4/AN electrolyte.

Supercapacitors have been attracting significant research interest because of their wide range of applications in electric vehicles, digital devices, pulsing techniques due to their high power density, short charging time, and long cycling life. For ideal charge/discharge mechanism, the micro/mesoporous silicon carbide flakes (SiCFs) with a high surface area of about 1376 m2 g−1 were 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. Two-electrode supercapacitor cells constructed with this silicon carbide yielded high values of gravimetric capacitance and energy density with aqueous and organic electrolytes. SiCF electrode carbonized at 1250 °C shows a high-charge storage capacity, with a specific capacitance of 49.2 F g−1 in 1 M KCl aqueous electrolyte at a scan rate of 5 mV s−1 (specific capacitance for the single electrode : 196.8 F g−1). In addition, a specific capacitance of 38.7 F g−1 is measured in 1 M 1-butyl-3-methyl-imidazolium tetrafluoroborate in acetonitrile (BMIM BF4/AN) organic electrolyte at a scan rate of 5 mV s−1 (specific capacitance for the single electrode: 154.8 F g−1), with an energy density of 65.84 W h kg−1; and ∼98.65% specific capacitance being retained over 20,000 cycles.