N, O-enriched hierarchical porous graphite carbon flake for high performance supercapacitors

Abstract

Super-high specific surface area (3319 m2 g−1) and N (3.64%), O (11.3%) containing hierarchical porous graphite carbon flake has been synthesized via simultaneous activation and graphitization of human harmful biomass-derived Firmiana simplex catkin. Due to the synergistic effects of KOH etching and carbide exfoliation, tube structure of C-700 can be effectively transformed the into flake structure of C-1-6. The C-1-6 based single electrode displays an excellent specific capacitance of 395 F g−1 at the current density of 0.5 A g−1 and superior rate capability with a high capacitance of 275 F g−1 at 50 A g−1. Furthermore, negligible 0.1% capacitance loss exists after 10,000 times of charging and discharge processes. Considerable energy densities of 11.52 Wh kg−1 and 55 Wh kg−1 can be obtained by solid-state and coin-type symmetric supercapacitors, respectively. This biomass-derived carbon can play a role in the field of carbon based supercapacitors.