Biomass waste derived from cassia fistula into value-added porous carbon electrode for aqueous symmetric supercapacitors

Activated carbon derived from biomass sources has been renowned as one of the key materials and economical precursors for numerous energy conversion and storage applications. Herein, we utilized a less explored Cassia fistula (Pulp and seed) biomass as the carbon source for supercapacitor application. Further, a less toxic and low activation method has been implemented to activate the biomass-derived carbon. The highly dense seed resulted in better porous compared to the pulp source. The electrochemical performances of the bio-carbon electrodes have been examined by CV, GCD, and EIS studies. The activated carbon derived from the Cassia fistula seed (CFSA) electrode achieved a specific capacitance value of 136.5 Fg−1 at 0.5 Ag−1 in 3 M KOH. Moreover, the electrode demonstrates an extremely long stability by sustaining 98 % of initial capacitance after 10,000 cycles, which signifies the robust electrochemical stability behavior of the obtained electrode. Further, the aqueous symmetric supercapacitor achieved a maximum energy and power density of 7.2 WhKg−1 and 3488.1 WKg−1, respectively. Likewise, after 10,000 stability cycles, the cell retains 96.4 % capacitance at 5 Ag−1 which denotes the noteworthy capacitive behaviour of the CFSA electrode. Thus, the present work suggests an eco-friendly resource for developing an effectual carbon electrode for energy storage applications.