Phosphonium-based protic ionic liquid as electrolyte for carbon-based supercapacitors

This study describes the use of a solution of a phosphonium protic ionic liquid [Bu3HP][BF4] (3.4 mol L-1) in acetonitrile as an electrolyte for carbon-based supercapacitors, with an operating voltage of 1.5 V and capacities comparable to conventional aqueous electrolytes. The combination of good cycling abilities and an operating temperature ranging from -40 degrees C to 80 degrees C rendered possible the realization of supercapacitors having an extended specific energy in a large temperature range. (C) 2011 Elsevier B.V. All rights reserved.