Preparation of biomass activated carbon with aligned graphene nanosheet arrays from bamboo parenchymal cells for supercapacitors

Abstract The increasing recognition of the need for economically viable carbon materials in supercapacitors has resulted in a notable emphasis on utilizing recycled biomass waste as a precursor for activated carbon (AC). This study investigates the production of highly porous AC through vertically aligned graphene nanosheet arrays (VAGNAs) derived from bamboo parenchyma cells, a type of biomass waste. The focus lies in manipulating the ratio of alkali to carbon during the activation process. Elevating the alkali-carbon ratio augments the specific surface area of the AC while concurrently reducing the presence of VAGNAs. Surprisingly, AC generated with an alkali-carbon ratio of four exhibits a remarkable specific capacitance of 215 F g−1 when subjected to a current density of 0.2 A g−1. When integrated into a supercapacitor apparatus, this AC material demonstrates a notable energy density of 11.2 W-hours per kilogram (Wh kg−1) at a power density of 50 W per kilogram (W kg−1). Moreover, it displays exceptional cycling stability, maintaining 89.4 % of its capacitance after undergoing 10,000 cycles in a 6 M potassium hydroxide electrolyte. The findings of this investigation underscore the potential of utilizing waste bamboo parenchyma cells for sustainable energy storage applications.