Charge Dynamics and Storage Behaviors of Ionic Liquids/Ionomer Electrolyte in Electroactive Devices

Abstract

Developing advanced electroactive devices requires the understanding of the influence of sample geometry on the charge transport and storage. In these devices both diffusion and drift processes depend on the distances over which ions travel. In this paper the charge dynamics of Aquivion membrane with 40 wt% uptake of EMI-Tf (1-ethyl-3-methylimidazolium trifluoromethane -sulfonate) cells were investigated over a broad membrane thickness (d) range. It was found that the double layer charging time τDL is linearly proportional to the thickness (d) for all applied voltages. However, in the longer time regimes (t>>τDL) under a high applied voltage (>0.5 V) where the significant charge storage occurs, it was found that the relationship between charge storage and applied voltage becomes nonlinear and also the longer time charging response of τdiff = d 2 / (4D), corresponding to the ion diffusion, was not observed.