Preparation of Cork-derived Porous Activated Carbon for High Performance Supercapacitors

The quercus variabilis cork made up of cavity cells is used as raw material. Herein, the cork-derived activated carbon with the various pores was successfully prepared by the facile carbonization of cork followed by chemical activation. The as-prepared activated carbon sheets possess large specific surface area (2312 m(2)/g) and unique interconnected pores. As a result, it shows excellent electrochemical performance as electrode material for supercapacitors. In three electrode system of KOH, it exhibits a high specific capacitance of 296 F/g at a current density of 0.1 A/g. The assembled symmetric supercapacitor shows a high specific capacitance of 201 F/g at 5 A/g, with a good cycling stability of 99.5 % capacitance retention after 5000 cycles. In two electrode system of Na2SO4, the symmetric supercapacitor displays a good rate performance of 80.5% retention from 0.5 A/g (174 F/g) to 50 A/g (140 F/g) and a high energy density of 19.62 Wh/kg.