Porous carbon derived from cashew nut husk biomass waste for high-performance supercapacitors

Biomass materials are regarded as ideal precursors for activated carbon owing to their unique structure. Here, a novel hierarchical carbon with a high surface area (2742 m2 g−1) and pore volume (1.528 cm3 g−1) is prepared from cashew nut husk biomass waste by a simple chemical activation. The as-obtained carbon is further assembled into electrodes and analyzed. In a three-electrode system, an optimal sample exhibits superior capacitive performance (305.2 F g−1 at 1 A g−1) and rate capability (256 F g−1 at 20 A g−1). Furthermore, a coin-type symmetric supercapacitor made from the optimal carbon sample exhibits a high energy density of 11.2 Wh kg−1 at 400 W kg−1, as well as excellent long-term cycling retention with 97.1% of the capacity being retained after 4000 charge-discharge cycles. Our work demonstrates that the porous carbon obtained from activated cashew nut husks presents great potential in the energy storage field.