Influence of Dielectric Constant on Ionic Transport in Polyether-Based Electrolytes

Abstract

We use all-atom molecular dynamics simulations to study the effect of polymer polarity, as quantified by the dielectric constant, on the transport properties of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) doped polyethers. Our results indicate that increasing the host dielectric constant leads to a decrease in ionic cluster sizes and reduction in correlated motion of oppositely charged ions. This causes the ionic conductivity to more closely approach the Nernst-Einstein limit in which ionic conductivity is only limited by the diffusivities of Li⁺ and TFSI^-. We compare our results to recent experimental observations which demonstrate similar qualitative trends in host polarity.