Decoupling of charge transport from structural dynamics in protic ionic liquids

Broadband dielectric spectroscopy, differential scanning calorimetry and rheology are employed to investigate charge transport and dynamics in protic and aprotic ionic liquids. While the structural $\alpha$-relaxation rates and the characteristic charge diffusion rates coincide for aprotic ionic liquids, the latter is found to be more than 100 times for the protic ionic liquids studied. Moreover, the analysis of protic ionic liquids revealed a decoupling of temperature dependence of ionic transport from that of structural relaxation with the degree of decoupling increasing with fragility of the liquid. The potential technological impact of these results will be discussed.