Non-solvating, side-chain polymer electrolytes with more dissociable pendent anion chemistries exhibit a dielectric relaxation dominated lithium ion transport mechanism.

The development of advanced electrolytes compatible with lithium metal and lithium-ion batteries is crucial for meeting ever growing energy storage demands. One such class of materials, single-ion conducting polymer electrolytes (SIPEs), prevents the formation of ion concentration gradients and buildup of anions at the electrode surface, improving performance. One of the ongoing challenges for SIPEs is the development of materials that are conductive enough to compete with liquid electrolytes. Presented herein is a class of gel SIPEs based on crosslinked poly­(tetrahydrofuran) diacrylate that present enhanced room temperature conductivities of 3.5 × 10–5 S/cm when gelled with lithium metal relevant 1,3-dioxolane/dimethoxyethane, 2.5 × 10–4 S/cm with carbonate solutions, and approaching 10–3 S/cm with dimethyl sulfoxide. Remarkably, these materials also demonstrate high ionic conductivity at low temperatures, 1.8 × 10–5 S/cm at −20 °C in certain solvents. Most importantly, however, when contrasted with identical SIPEs formulated with poly­(ethylene glycol) diacrylate, the mechanisms responsible for the enhanced conductivity are elucidated: decreasing Li+–polymer interactions and gel solvent–polymer interactions leads to an increase in Li+ mobility. These findings are generalizable to various SIPE chemistries and can therefore be seen as an additional set of design parameters for developing future high conductivity SIPEs.

Batteries based on alternatives to lithium are now of global research interest. Magnesium metal batteries are particularly attractive for their potential high energy density. Polymer electrolytes for high density rechargeable batteries have been sought for decades, due to their improved thermal stability compared with liquids and their lower density and cost compared with inorganic solids. Yet, little success has so far been realized in polymer electrolytes for magnesium metal batteries. In this review, the magnesium polymer electrolyte literature is comprehensively explored. Differences between requirements for lithium polymer and magnesium polymer batteries are discussed as well as the consequences on necessary considerations for impactful magnesium polymer electrolyte research.