Ion Transport in Polymer Blend Electrolytes*

In conventional small-molecule battery electrolytes, high ionic conductivity is achieved through blending of high polarity and low viscosity components. One may simply assume that the conductivities of these blended electrolytes will be an average of the intrinsic conductivities of each host, each of which is weighted by its volume fraction. However, it has been shown that the ionic conductivity is instead a nonmonotonic function of the volume fraction of each host, maximizing at some intermediate blend composition.

Inspired by these results in small molecule electrolytes, we hypothesize similar nonlinearities may occur in polymeric blend electrolytes. In this work, we seek to examine the effect of blending polymeric hosts by using the Stockmayer polarity model in a coarse-grained molecular dynamics framework, which we have previously used to describe the role of host polarity on ionic conductivity. We first investigate the role of host polarity contrast (measured by the difference in monomeric dipole strength) and blend composition on blend phase stability and segmental dynamics. We then correlate these properties with the resultant ionic conductivities of these electrolytes.