A lithium-polymer battery based on an ionic liquid-polymer electrolyte (IL-PE) composite membrane operating at room temperature is described. Utilizing a polypyrrole coated LiV308 cathode material, the cell delivers >200 mAh g-1 with respect to the mass of the cathode material. Discharge capacity is slightly higher than those observed for this cathode material in standard aprotic electrolytes; it is thought that this is the result of a lower solubility of the LiV308 material in the IL-PE composite membrane. (c) 2008 Elsevier Ltd. All rights reserved.