Polyelectrolyte-in-ionic-liquid electrolytes

Novel polymer electrolyte materials based on a polyelectrolyte-in-ionic-liquid principle are described. A combination of a lithium 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSLi) and N,N′-dimethylacrylamide (DMMA) are miscible with the ionic liquid, 1-ethyl-3-methylimidazolium dicyanamide (EMIDCA). EMIDCA has remarkably high conductivity (≥ 2 · 10−2 S · cm−1) at room temperature and acts as a good solvating medium for the polyelectrolyte. At compositions of AMPSLi less than or equal to 75 mol-% in the copolymer (P(AMPSLi-co-DMAA)), the polyelectrolytes in EMIDCA are homogeneous, flexible elastomeric gel materials at 10 − 15 wt.-% of total polyelectrolyte. Conductivities higher than 8 · 10−3 S · cm−1 at 30 °C have been achieved. The effects of the monomer composition, polyelectrolyte concentration, temperature and lithium concentration on the ionic conductivity have been studied using thermal and conductivity analysis, and pulsed field gradient nuclear magnetic resonance techniques.