Hierarchical Porous Carbons Derived from Renewable Poplar Anthers for High-Performance Supercapacitors

Hierarchical porous carbons with granular shape were prepared from waste biomass poplar anthers (PA) by pre-carbonization and following KOH activation. The pore structure and surface chemistry of PA-derived carbon can be controlled by adjusting the activation temperature. The material activated at 800 degrees C possesses a high surface area of 3639 m(2)g(-1), abundant mesopores, and appropriate amounts of oxygen- and nitrogen-containing species. As a result, it exhibits excellent electrochemical performances as a supercapacitor electrode. The specific capacitance reaches 361.5 Fg(-1) at a current density of 0.5 Ag-1 in 6 M KOH aqueous solution. In addition, it shows an impressive energy density of 60.8 Whkg(-1) at a power density of 10416.7 Wkg(-1) in the ionic liquid BMIMBF4. Particularly, a high electrochemical stability and an excellent reversibility were observed in both aqueous and non-aqueous electrolytes.