2014 Volume 93 Issue 10 Pages 1015-1020
AC impedance spectroscopic approach is applied into room temperature ionic liquid (RTIL) based mixtures. The RTIL is hydrophobic 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [C2mim][TFSI]. For higher efficient electric double layer capacitor (EDLC) as an energy storage device, Cu3Au nanoporous electrode is assembled in the [C2mim][TFSI]-propanol mixtures. Due to high cost and high viscosity of the pure [C2mim][TFSI], an additive is required in order to achieve the low cost and quick electrochemical response for rapid charge/discharge. Propanol having relative low vapor pressure among alcohols is adequate to reduce viscosity of the hydrophobic RTILs. With nanoporous metallic electrode, the EDL capacitance in the mixtures exceed that in the pure [C2mim][TFSI]. Also, the capacitance in the mixtures was large enough up to 80 mol% propanol. In addition, isomer effect of propanol was seen in the AC impedance spectra.