Preparation, characterization and impedance spectroscopic studies of Na+ ion conducting PEO + PVDF-blended polymer electrolytes

Abstract

The films of poly (ethylene oxide) (PEO) and poly (vinylidene fluoride) (PVDF)-based blended polymer electrolyte films complexed with sodium perchlorate (NaClO4) salt were prepared using the solution casting method. The complexation of NaClO4 salt with the blend of polymers PEO and PVDF was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The melting temperatures were measured by differential scanning calorimetry (DSC). The surface morphology was examined by scanning electron microscopy (SEM). The prepared films were subjected to electrical impedance spectroscopy (EIS) to investigate ionic conductivity, dielectric and electrical modulus studies. It was observed that adding a small amount of PVDF to the PEO host polymer improves the interaction between the ions and the polymer and results in more ionic dissociation. Consequently, the number of active mobile carriers in the polymer matrix increases. The ionic conductivity studies have shown the maximum conductivity 2.84 × 10−6 S/cm at 303 K for the polymer blend 0.8PEO + 0.2PVDF complexed with 5 wt% NaClO4 and it is attributed to a decrease in crystallinity. Ionic transport numbers of various prepared samples were measured using Wagner’s polarization technique.