Polyvinyl alcohol (PVA)–polyethylene glycol (PEG) based solid polymer blend electrolytes with magnesium nitrate have been prepared by the solution cast technique. Impedance spectroscopic technique has been used, to characterize these polymer electrolytes. Complex impedance analysis was used to calculate bulk resistance of the polymer electrolytes. The a.c.-impedance data reveal that the ionic conductivity of PVA–PEG–Mg(NO₃)₂ system is changed with the concentration of magnesium nitrate, maximum conductivity of 9.63 × 10^-5 S/cm at room temperature was observed for the system of PVA–PEG–Mg(NO₃)₂ (35–35–30). However, ionic conductivity of the above system increased with the increase of temperature, and the highest conductivity of 1.71 × 10^-3 S/cm was observed at 100°C. The effect of ionic conductivity of polymer blend electrolytes was measured by varying the temperature ranging from 303 to 373 K. The variation of imaginary and real parts of dielectric constant with frequency was studied.

Composite polymer electrolytes based on poly(ethylene glycol) (PEG), magnesium acetate [Mg(CH₃COO)₂], and 𝑥 wt% of cerium oxide (CeO₂) ceramic fillers (where 𝑥 = 0, 5, 10, 15 and 20, respectively) have been prepared using solution casting technique. X-ray diffraction patterns of PEG–Mg(CH₃COO)₂ with CeO₂ ceramic filler indicated the decrease in the degree of crystallinity with increasing concentration of the filler. DSC measurements of PEG–Mg(CH₃COO)₂-CeO₂ composite polymer electrolyte system showed that the melting temperature is shifted towards the lower temperature with increase of the filler concentration. The conductivity results indicate that the incorporation of ceramic filler up to a certain concentration (i.e. 15 wt%) increases the ionic conductivity and upon further addition the conductivity decreases. The transference number data indicated the dominance of ion-type charge transport in these specimens. Using this (PEG–Mg(CH₃COO)₂-CeO₂) (85-15-15) electrolyte, solid-state electrochemical cell was fabricated and their discharge profiles were studied under a constant load of 100 k𝛺.