FTIR, XRD and ac impedance spectroscopic study on PVA based polymer electrolyte doped with NH4X (X = Cl, Br, I)

The present study focuses on characterizing PVA: NH4X (X = Cl, Br, I) proton conducting polymer electrolyte prepared by solution casting technique using XRD, FTIR and ac impedance spectroscopic studies. The XRD patterns of all the prepared polymer electrolytes reveal the amorphous nature of the films. The FTIR spectroscopic study indicates the detailed interaction of PVA with proton. From ac impedance spectroscopic studies, it has been found that PVA doped with NH4I have high ionic conductivity (2.5 × 10−3S cm−1) than PVA doped with NH4Br (5.7 × 10−4S cm−1) and NH4Cl (1.0 × 10−5S cm−1) polymer electrolytes. This is due to the large anionic size and low lattice energy of NH4I (in comparison with NH4Br and NH4Cl).The temperature dependence of ionic conductivity for all the PVA: NH4X (X = Cl, Br, I) polymer films obey Arrhenius equation. Ionic transference number measured has been found to be in the range of 0.93–0.96 for all the polymer electrolytes proving that the total conductivity is mainly due to ions.