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 °C to 1100 °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 N2 sorption experiments were performed and the specific micropore surface areas from 1100 m2 g−1 up to 2270 m2 g−1 were obtained, depending on the extent of CO2 activation. The energy and power density characteristics of the supercapacitors based on 1 M (C2H5)3CH3NBF4 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.

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