Enhancement of Na⁺ ion conduction in polymer blend electrolyte P(VdF-HFP) – PMMA- NaTf by the inclusion of EC

Polyvinylidenefluoride-co-hexafluoropropylene(PVdF-HFP) and polymethylmethacrylate (PMMA) and sodium triflate(NaTf) were used to prepare P(VdF-HFP)-PMMA-NaTf electrolytes using solution casting technique. The liquid plasticizer ethylene carbonate (EC) was added to the electrolytes in different concentrations say 10, 20, 30 and 40 wt% to achieve the enhancement of Na⁺ ion conduction at room temperature. Ionic conductivity of the samples was determined using AC impedance analysis and it was 7.86 × 10⁻⁸ S cm⁻¹ for the polymer blend electrolyte at room temperature. Inclusion of EC was found to enhance the Na⁺ ion conduction and maximum value of ionic conductivity, 1.86 × 10⁻⁴ S cm⁻¹, was obtained for the EC concentration of 30 wt%. This observation was explained on the basis of FTIR, XRD and AFM analysis of the samples which revealed the enhanced EC-polymer interaction and hence fast ion transport. Larger increase of dielectric constants and the reduced dielectric loss of EC added polymer blend electrolytes revealed the increase of the number of free Na⁺ ions. Thermal analysis of the samples was done through TGA-DTG technique and the thermal stability was found to decrease after the addition of EC.