Characterization of plasticized solid polymer electrolyte by XRD and AC impedance methods

Polymer electrolyte films prepared from poly(ethylene oxide) and lithium hexafluoroarsenate with varying composition of dibutylphthalate, the plasticizing agent, are studied by X-ray diffraction and AC impedance. A film containing 0.09 mol of dibutylphthalate is an optimum electrolyte composition by virtue of its free-standing ability with reasonably high conductivity. A film with this composition exhibits an enhanced amorphous character and a reduced energy barrier to segmental motion which favours lithium-ion conduction through the film. The temperature dependence of the complex film, with and without plasticizer, appears to obey the Arrhenius Law. The activation energy is 0.578 kJ/mol, which is considerably lower than the value of 10 kJ/mol that is obtained for a film without a plasticizer.