We report an investigation on quaternary, polyethylene oxide (PEO)-based electrolytes as separators for lithium polymer batteries. The target is the development of Li+ conducting membranes, containing large fraction of the N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl) imide ionic liquid, able to combine fast ion transport properties with improved electrochemical stability. The PEO electrolytes, prepared through a fully-dry solvent-free procedure, exhibited good aging resistance and conductivity values equal to 3.46 x 10(-4) and 2.43 x 10(-3) S cm(-1) at -20 and 20 degrees C, respectively, combined with an anodic stability up to 4.5 V (vs. Li degrees/Li+). These results represent the best performance, in terms of ion transport properties and electrochemical stability, reported till now for PEO electrolytes. (C) 2017 Elsevier Ltd. All rights reserved.