Performance of C/C electric double layer capacitors with coal-based active carbon electrodes

Coal-based active carbon was prepared and used as electrodes of electric double-layer capacitors (EDLCs). The performance of EDLCs using active carbon electrodes with different pore structure was studied, including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. With an increase of sodium hydrate/coal ratio, the pore structure of active carbon is greatly improved, resulting in larger double-layer capacitance. The capacitance of asymmetric EDLC is up to 65.98 F/g. Moreover, it is found that different pore structure of active carbon is necessary for positive and negative electrodes. Asymmetric EDLC not only exhibits high capacitance but also shows excellent charge-discharge performance, suggesting that it is very suitable and promising to design electrode materials for supercapacitors.