Hierarchical porous biochar derived from cotinus coggygria flower by using a novel composite activator for supercapacitors

Abstract Hierarchical porous biochar with large BET surface area of 959.04 cm2 g−1 was synthesized by using a novel composite activator from cotinus coggygria flowers. The biochar delivers excellent specific capacitance of 413.5 F g−1 at current density of 0.5 A g−1 in 1 M H2SO4 electrolyte and a well reversible capacitance of 279.9 F g−1 at current density of 5 A g−1 in 6 M KOH electrolyte after 36,000 cycles. The excellent specific capacitance and the stable cycling performance benefit from the synergism of the composite activator. This provides a meaningful reference for the synthesis of supercapacitor biomaterials.