Impact of Ionic Correlations on Conductivity of Polymerized Ionic Liquids

Polymerized ionic liquids (PolyILs) have garnered significant attention as potential candidates for electrolytes in electrochemical energy technologies due to their combination of good mechanical properties of polymers and high ion transport number. However, the low conductivity remains a major obstacle for their widespread practical application. One of the reasons for conductivity suppression in PolyILs is related to the strong ionic correlations, which can decrease ionic conductivity by more than one order of magnitude. However, the mechanisms behind these correlations are not yet fully understood. In this study we synthesized different types of poly cations, which can serve as a matrix for doped Li or Na salt. Using different types of pendant groups, we studied the effect of matrix flexibility and charge delocalization on transport properties of mobile anions. Substituting the anions from Br to BF4, PF6 and TFSI, we also studied the effect of anion size on the overall conductivity. For this purpose, we employed a set of experimental techniques including dielectric spectroscopy in a wide frequency range, differential scanning calorimetry and light scattering. The obtained insights will be used as guidance for rational design of polymer structure that will provide high ionic conductivity.