NaClO4 and NaPF6 as potential non-aqueous electrolyte salts for electrical double layer capacitor application

1 M NaClO4 and 1 M NaPF6 electrolyte solutions in ethylene carbonate-dimethyl carbonate solvent mixture (1:1 by volume) were studied for the possible application in electrical double layer capacitors (EDLCs) with carbide-derived carbon electrodes (synthesized from Mo2C). Two- and three-electrode test cells were electrochemically characterized by using cyclic voltammetry, constant current charge/discharge and electrochemical impedance spectroscopy methods. Region of ideal polarizability, values of series capacitance, high-frequency resistance, time constants, etc. have been established. Based on the specific energy and power calculations, and other characteristics, it was found that the Na-salts based EDLC test cells have similar electrochemical behavior compared to LiPF6 and LiClO4 based systems that have been studied earlier. The studied Na-salts based electrolytes are potential candidates for EDLCs, however, future improvement of the cyclability is inevitable to achieve long-lasting high performance. (C) 2012 Elsevier Ltd. All rights reserved.