Huge enhancement of energy storage capacity and power density of supercapacitors based on the carbon dioxide activated microporous SiC-CDC

Nanostructured carbide-derived carbons (CDC) were synthesized from SiC powders (SiC-CDC) via gas phase chlorination within the temperature range from 1000 degrees C to 1100 degrees C. Thereafter the CDCs were additionally activated by CO2 treatment method, resulting in nearly two-fold increase in specific surface area. The results of X-ray diffraction, high-resolution transmission electron microscopy and Raman spectroscopy showed that the synthesized CDC materials are mainly amorphous, however containing small graphitic crystallites. The low-temperature N-2 sorption experiments were performed and the specific micropore surface areas from 1100 m(2) g(-1) up to 2270 m(2) g(-1) were obtained, depending on the extent of CO2 activation. The energy and power density characteristics of the supercapacitors based on 1M (C2H5)(3)CH3NBF4 solution in acetonitrile and SiC-CDC as an electrode material were investigated using the cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic charge/discharge and constant power discharge methods. The electrochemical data indicated two-times increase in specific capacitance. Most importantly, the activation of SiC-CDC with CO2 significantly increases the performance (energy density, power density, etc.) of the supercapacitors especially at higher potential scan rates and at higher power loads. (C) 2015 Elsevier Ltd. All rights reserved.