The electrochemical properties of solvent-free, ternary polymer electrolytes based on a novel poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide polymeric ionic liquid (PIL) as polymer host and incorporating PYR14TFSI ionic liquid and LiTFSI salt are reported. The PIL–LiTFSI–PYR14TFSI electrolyte membranes were found to be chemically stable even after prolonged storage times in contact with lithium anode and thermally stable up to 300°C. Particularly, the PIL-based electrolytes exhibited acceptable room temperature conductivity with wide electrochemical stability window, time-stable interfacial resistance values and good lithium stripping/plating performance. Preliminary battery tests have shown that Li/LiFePO4 solid-state cells are capable to deliver above 140mAhg−1 at 40°C with very good capacity retention up to medium rates.