The electrochemical properties of solvent-free, quaternary polymer electrolytes based on a novel polymeric ionic liquid (PIL) as polymer host and incorporating 1g13TFSI ionic liquid, LiTFSI salt and nano-scale silica are reported. The PIL–LiTFSI–1g13TFSI–SiO2 electrolyte membranes are found to be chemically stable even at 80°C in contact with lithium anode and thermally stable up to 320°C. Particularly, the quaternary polymer electrolytes exhibit high lithium ion conductivity at high temperature, wide electrochemical stability window, time-stable interfacial resistance values and good lithium stripping/plating performance. Batteries assembled with the quaternary polymer electrolyte at 80°C are capable to deliver 140mAhg−1 at 0.1C rates with very good capacity retention.