Steam and Carbon Dioxide Co-Activated Silicon Carbide-Derived Carbons for High Power Density Electrical Double Layer Capacitors

Abstract

Different mico-mesoporous silicon carbide-derived carbons (SiC-CDC) were synthesized via gas phase chlorination at 1100°C and thereafter activated at 900°C and 1000°C with H2O steam using Ar and CO2 as the carrier gases. The physical characterization data show that these materials are mainly amorphous, the structure does not change remarkably during the activation process and the surface chemistry of the differently activated and treated materials remains the same and there are no functional groups at the SiC-CDC surface. N2, Ar and CO2 sorption measurements indicate an increase in the specific surface area and pore size distribution with increasing the activation temperature, whereas the influence of the carrier gas during synthesis is minimal. Although the specific surface areas and pore size distributions differed, the electrochemical parameters in 1 M (C2H5)3CH3NBF4 acetonitrile solution for all SiC-CDC materials were similar - specific gravimetric capacitances 130 ± 18 F g−1 and volumetric capacitance 67 ± 14 F cm−3 were calculated. Absolute phase angle values from −85° to −88° at low frequencies and very high energy and power densities 22 Wh kg−1 at 20 kW kg−1 and 12 Wh dm−3 at 10 kW dm−3 have been achieved.