Pathways for Superionic Transport in Single-Ion Conducting Polymer Blend Electrolytes

Single-ion conducting polymer electrolytes (SICPEs) present an opportunity to improve the safety and performance of batteries or other electrochemical devices, but achieving high conductivity is still a significant challenge, due to the coupling of ion transport with polymer segmental dynamics. This work focuses on correlating nanoscale morphology with ion and polymer dynamics in single-cation conducting polymers, in particular blend SICPEs, which leverage the ion transport of a mobile solvating polymer with the safety and stability of the SICPE. By blending SICPEs with a low molecular weight polymer, nanoscale ionic aggregates may be swollen with the solvating polymer, which facilitates the rapid transport of cations. Experimental techniques such as broadband dielectric spectroscopy and X-ray scattering are used to highlight how these solvated nanochannels may lead to the mechanism of superionic transport, in which ion motion is faster than the polymer segmental dynamics. The impact of SIC polymer backbone (poly(methyl methacrylate) vs. polystyrene) functionalized with a TFSI anion is studied for different mobile cations, with a low MW polyethylene oxide as the solvating polymer. This work will aid in the development of design rules for achieving superionic transport in SICPE blends.