A study of the electrochemical properties of a PEO-based polymer electrolyte with nanometric ZrO2 as ceramic filler has been carried out in order to confirm an earlier reported model dealing with the role of ceramic fillers within PEO-based polymer electrolytes as components that enhance such properties as conductivity, lithium transference number, compatibility with lithium metal electrodes and cyclability. A prototype of a lithium polymer battery, based on a membrane made from a nanocomposite polymer electrolyte doped with ZrO2, utilizing LiFePO4+1% Ag as cathode, has been assembled and galvanostatically cycled, resulting in excellent performance at temperatures ranging from 100degreesC to 60degreesC (close to the crystallization temperature of PEO).