Composite electrolytes based on low molecular weight polyglycols

In the present work ionic conduction is studied in poly(ethylene glycol) (PEG)–LiClO4–α-Al2O3 electrolytes over wide salt concentration and temperature ranges. Composite electrolytes with α-Al2O3 containing inert surface groups are examined. Conductivity enhancement was observed compared to PEG–LiClO4 electrolytes in the 0.5–5 mol kg−1 salt concentration range. Conductivity studies are coupled to viscosity and DSC experiments which helps us to establish the relation between salt concentration and viscosity (flexibility) of the polymer host. The ion–polymer interactions are studied on the basis of FT-IR spectroscopy and, particularly, changes in the intensity of the IR modes characteristic of C–O–C vibrations. Finally, the ionic associations are discussed on the basis of the Fuoss–Krauss formalism. These studies show the reduction in the ion-pair formation for composite polymeric electrolytes in the entire concentration range studied.