American ginseng biowaste-derived activated carbon for high-performance supercapacitors

Biomass wastes are ecofriendly and economical precursors of activated carbon for supercapacitors. In this work, activated carbon was prepared via precarbonization and KOH activation using American ginseng waste residue (AGWR) as the precursor. The evolution of the activated carbon structure with increasing activation degree was systematically studied. A high specific surface area (2187 m2/g) and good pore distribution were achieved at a KOH/carbon ratio of 3:1, which delivered a high specific capacitance of 268 F/g in a 6 M KOH electrolyte. A symmetrical aqueous supercapacitor constructed using this activated carbon could achieve a high energy density of 18.6 Wh/kg and a power density of 10 kW/kg at 20 A/g. Moreover, the as-obtained supercapacitor maintained 97.47% of the initial capacitance after 10,000 cycles, indicating an outstanding electrochemical stability. This work shows that AGWR can be a good raw material to prepare high-performance activated carbon for supercapacitors.