Three-dimensional flower-like and hierarchical porous carbon materials as high-rate performance electrodes for supercapacitors

Three-dimensional flower-like and hierarchical porous carbon material (FHPC) has been fabricated through a simple and efficient carbonization method followed by chemical activation with flower-like ZnO as template and pitch as carbon precursor. The hierarchical porous structure is composed of numerous micropores and well-defined mesopores in the interconnected macroporous walls. The FHPC electrode can achieve a relatively high capacitance of 294 F g(-1) at a scan rate of 2 mV s(-1) and excellent rate capability (71% retention at 500 mV s(-1)) with superior cycle stability (only 2% loss after 5000 cycles) in 6 mol L-1 KOH electrolyte. The symmetric supercapacitor fabricated with FHPC electrodes delivers a high energy density of 15.9 Wh kg(-1) at a power density of 317.5W kg(-1) operated in the voltage range of 0-1.8 V in 1 mol L-1 Na2SO4 aqueous electrolyte. (C) 2013 Elsevier Ltd. All rights reserved.