Physicochemical synthesis of activated carbon from Canna indica (biowaste) for high-performance supercapacitor application

Activated carbon is the most commonly used electrode material in electrochemical double-layer capacitors. The rational utilization of biomass (waste) to prepare porous activated carbon as efficient electrode material for supercapacitor application is observed. Herein, we have prepared activated carbon from Canna indica as a tolerable and earth-bountiful carbon source via the facile physicochemical method. The microwave method has provided the highest order of activated carbon with an irregular partial lamellar structure morphology compared to the traditional activation method. Microwave-assisted acid-treated activated carbon (R3 sample) exhibited superior electrochemical properties compared with other samples (as-prepared biochar (R1 sample) and chemically activated (R2 sample)). Hence, R3 coated conductive electrode offered a high Cs of 112.9. F/g at 4 A/g in 1 M Na2SO4 with the cyclability of 76.8% after 3000 cycles at 20 A/g. A fabricated symmetric R3//R3 device showed the Cs of 54.3 F/g at 1 A/g with the energy/power density of 14.8 Wh/kg and 666.5 W/kg. The symmetric device offered a high cyclability of 86% after 3000 cycles at 20 A/g. This work delivers an effective tactic and cost-effective approach for synthesizing of activated carbon as a value-added product from biowaste for energy storage applications.