The electrochemical performance of polymer-based batteries can be improved by the addition of inorganic fillers to the polymer electrolyte, giving composite polymer electrolytes. The use of polymer nanocomposites, where the dimensions of the filler particles are reduced, should lead to the improvement of the performance of the electrolytes. Here, the direct intercalation of poly(ethylene oxide) into Na+ and Li+-exchanged layered silicates and the properties of the resulting nanocomposites is reported.