Novel electrolytes based on mixtures of dimethyl sulfoxide task specific zwitterionic ionic liquid and lithium salts: Synthesis and conductivity studies

Novel methyl sulfoxide imidazolium-based zwitterionic low melting salts was synthesized and characterized. The combination of this functionalized zwitterion and lithium bis(trifluoromethylsulfonyl)amide (LiNTf2) salts at different molar ratios of render to low melting mixtures, which can exhibit an ionic conductivity as high as 3.4 x 10-5 S cm-1 at 30 degrees C or 2.9 x 10-3 S cm- 1 at 120 degrees C and a high thermal decomposition temperature higher than 250 degrees C. The thermal activation energy shown two clearly different Arrhenius trend. For all the mixtures the temperature where the slope of the Arrhenius plot changes is on the range of the melting temperature experimentally observed for the mixture. Below the melting temperature, the values of activation energy are around of two times higher than the values observed for all the mixtures above the melting temperature. On the other hand, in all the mixtures, we have observed that conductivity increases monotonically on the composition of the mixture. These non-volatile and highly polar novel materials can be used for the development of devices targeting high ionic Li-ion conductivity.