, therefore it supported the increasing mobility of the cation, i.e. [EMIM] + . The ionic conductivity of the RTIL system is also compared to ξr and shown in Figure (supporting information). It could be observed from Figure (a) (supporting information) that with the increase of the relative ion dissociation value, ionic conductivity increases, and it reaches the maximum value at the maximum ion dissociation, then ξr further decreases due to the viscous forces and size of the solvated ions, which hinders the mobility of the ion, it reaches the minimum for neat RTILs where viscosity and size of the ions were maximum. In addition, Lee and Lin 18 studied ion dissociation phenomena computationally in various IL/water systems, including [EMIM][ETSO4], finding a minimum dissociation where free ion activity is dominated by solvent-induced dielectric polarization. The ion dissociation minimum changes with IL concentration. The dissociated ions are solvated mainly through the solvent in the dilute region. In contrast, the ion pair stabilizes the free ions in the high concentration limit.