Gel polymer electrolytes consisted of poly(alkylene oxide) (PAO), LiBF4 or LiClO4, and aprotic solvents (gamma-butyrolactone (GBL) and/or ethylene carbonate (EC)) were prepared and the conductivity was measured. The conductivity was very high and similar to that of the organic liquid electrolytes. The performance of Li \ gel polymer electrolyte \ LiCoO2 cell was measured and compared to that of the cell with the liquid electrolyte corresponded. The cell with the gel electrolyte showed a decrease of capacity at high-rate discharge and low temperature owing to concentration polarization. (C) 2003 Elsevier Science B.V. All rights reserved.