Hierarchical porous carbons with controlled micropores and mesopores for supercapacitor electrode materials

Various porous carbons were prepared by CO2 activation of ordered mesoporous carbons and used as electrode materials for supercapacitor. The structures were characterized by using X-ray diffraction, transmission electron microscopy and nitrogen sorption at 77 K. The effects of CO2 treatment on their pore structures were discussed. Compared to the pristine mesoporous carbons, the samples subjected to CO2 treatment exhibited remarkable improvement in textural properties. The electrochemical measurement in 6 M KOH electrolyte showed that CO2 activation leads to better capacitive performances. The carbon CS15A6, which was obtained after CO2 treatment for 6 h at 950 degrees C using CMK-3 as the precursor, showed the best electrochemical behavior with a specific gravimetric capacitance of 223 F/g and volumetric capacitance of 54 F/cm(3) at a scan rate of 2 mV/s and 73% retained ratio at 50 mV/s. The good capacitive behavior of CS15A6 may be attributed to the hierarchical pore structure (abundant micropores and interconnected mesopores with the size of 3-4 nm), high surface area (2749 m(2)/g), large pore volume (2.09 cm(3)/g), as well as well-balanced microporosity and mesoporosity. (C) 2008 Elsevier Ltd. All rights reserved.