Mixtures of ionic liquids for low temperature electrolytes

The conductivity, viscosity and the self-diffusion coefficient of pyrrolidinium-based ILs (ILs), N-butyl-N-methyl pyrrolidinium-bis(trifluoromethanesulfonyl)imide (Pyr(14)TFSI) and N-methyl-N-propyl pyrrolidinium-bis(fluorosulfonyl)imide (Pyr(13)FSI), and their binary mixtures were investigated in order to better understand their behavior as electrolyte components in supercapacitor and lithium battery systems. The IL mixtures showed excellent low temperature properties far exceeding those of the pure IL materials. For example, at -40 degrees C the conductivity of binary mixtures was found to be up to four orders of magnitude higher than that of the pure ILs. (c) 2012 Elsevier Ltd. All rights reserved.