Polymer‐in‐ionic‐liquid electrolytes

In order to achieve high conductivity in a polymer electrolyte, polymer‐in‐ionic‐liquid electrolytes have been explored. It is found in this study that polyvinylpyrrolidone‐co‐(vinyl acetate)] (P(VP‐c‐VA)) in 1‐ethyl‐3‐methylimidazolium bis(trifluoromethyl sulfonyl) amide (EtMeIm⁺Tf₂N⁻) and poly(N,N‐dimethyl acrylamide) (PDMAA) in trimethyl butyl ammonium bis(trifluoromethane sulfonyl) amide (N₁₁₁₄⁺Tf₂N⁻) produce ion‐conducting liquids and gels. The P(VP‐c‐VA)/ EtMeIm⁺Tf₂N⁻ mixture has a conductivity around 10⁻³ S · cm⁻¹ at 22 °C, for copolymer concentrations up to 30 wt.‐%. Thermal analysis shows that the T_g of the P(VP‐c‐VA)/ EtMeIm⁺Tf₂N⁻ system is well described by the Fox equation as a function of polymer content. Poly(methyl methacrylate) (PMMA)/ EtMeIm⁺Tf₂N⁻ gel electrolytes were prepared by in‐situ polymerisation of the monomer in the ionic liquid. In the presence of 0.5–2.0 wt.‐% of a crosslinking agent, these PMMA‐based electrolytes displayed elastomeric properties and high conductivity (ca. 10⁻³ S · cm⁻¹) at room temperature.

Conductivity versus temperature in crosslinked PMMA/ EtMeIm⁺Tf₂N⁻ gel electrolytes with different concentrations of crosslinking agent.