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 m(2) g(-1)) and pore volume (1.528 cm(3) 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. (C) 2020 Elsevier B.V. All rights reserved.