The use of binary mixtures of 1-butyl-l-methylpyrrolidinium bis {(trifluoromethyl)sulfonyl}imide and aliphatic nitrile solvents as electrolyte for supercapacitors

The development of high voltage electrolytes is one of the key aspects for increasing both energy and power density of electrochemical double layer capacitors (EDLCs). The usage of blends of ionic liquids and organic solvents has been considered as a feasible strategy since these electrolytes combine high usable voltages and good transport properties at the same time. In this work, the ionic liquid 1-butyl-1-methylpyrrolidinium bis{(trifluoromethyl)sulfonyl}imide ([Pyrr(14)][TFSI]) was mixed with two nitrile-based organic solvents, namely butyronitrile and adiponitrile, and the resulting blends were investigated regarding their usage in electrochemical double layer capacitors. Both blends have a high electrochemical stability, which was confirmed by prolonged float tests at 3.2 V, as well as, good transport properties. In fact, the butyronitrile blend reaches a conductivity of 17.14 mS center dot cm(-1) and a viscosity of 2.46 mPa center dot s at 20 degrees C, which is better than the state-of-the-art electrolyte (1 mol center dot dm(-3) of tetraethylammonium tetrafluoroborate in propylene carbonate). (C) 2016 Elsevier Ltd. All rights reserved.