The results of detailed studies of the ionic conductivity, ultrastructure, and morpholgy of polyether−poly(N,N-dimethylacrylamide)−LiClO4 electrolytes are presented and discussed. These composite electrolytes have been studied using differential scanning calorimetry (−110−150 °C), with FT-IR spectroscopy (20−85 °C) and impedance analysis (−20−100 °C). Room temperature FT-Raman spectroscopy, SEM, and X-ray energy dispersive studies have also been performed. Highly crystalline poly(ethylene oxide) and amorphous or low-crystalline oxymethylene-linked poly(ethylene oxide) are used as polyether matrices for composite electrolytes. It is shown that interactions of lithium cations with polyether oxygens and the carbonyl oxygens of the “filler” poly(N,N-dimethylacrylamide) lead to the formation of various types of complexes. These interactions can be classified as Lewis acid−base reactions. The formation of different types of complexes modifies the ultrastructure and enhances the subambient and ambient temperatur...