Effects of Salt Concentration and Blend Composition on Ionic Transport Mechanisms in Solid Polymer Blend Electrolytes

Solid polymer blend electrolytes (SPBEs) hold great potential as alternatives to conventional liquid electrolytes, offering improved mechanical properties and enhanced ionic conductivity. Achieving both requires the careful selection of polymer components. In previous work, we demonstrated that using low molecular weight poly(ethylene glycol) (PEG) in SPBEs suppressed crystallization and enhanced micro-dynamics, resulting in a notable ionic conductivity of approximately 0.3 mS/cm at room temperature. However, a comprehensive understanding of the ionic transport mechanisms is still needed to further optimize the performance of SPBEs.

In this study, we focus on the distinct roles of PEG, a representative coordinating polymer, and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), a non-coordinating polymer, in the ionic transport mechanisms within SPBEs. Specifically, we investigate how these mechanisms interact when the two polymers are blended to form the electrolyte matrix. Through Vogel-Tamman-Fulcher (VTF) analysis, we observed that both activation energy and Vogel temperature vary with the blend ratio and lithium salt concentration. Additionally, we examined the structural changes in relation to composition, providing further insight into the design of high-performance SPBEs.