Study on blend polymer (PVA-PAN) doped with lithium bromide

Abstract

Blend polymer electrolyte membranes that consist of poly(vinyl alcohol) (PVA), poly (acrylonitrile) (PAN) and different concentrations of lithium bromide (LiBr) have been prepared by solution casting technique using dimethylformamide (DMF) as solvent. The amorphous nature of the blend polymer (92.5 PVA: 7.5 PAN)—salt complexes has been confirmed by X-ray diffraction analysis. The formation of blend polymer (92.5 PVA: 7.5 PAN)—salt complexes has been confirmed by Fourier transform infrared spectral studies. The decrease in glass transition temperature (T g) with the salt reveals the increase in segmental motion. Conductivity studies have been carried out using ac impedance spectroscopy and it has been found that, the maximum ionic conductivity is 3.0 × 10–4 S cm–1 for 30 wt % LiBr doped—92.5 PVA: 7.5 PAN electrolyte. The temperature dependence of conductivity of the blend polymer electrolyte has been discussed. The activation energy is calculated for all compositions of blend polymer doped with LiBr using Arrehenius plot. The dielectric spectra show low frequency dispersion. Ionic transference number (t +) has been found to be 0.98 for the blend polymer (92.5 PVA: 7.5 PAN) with 30 wt % LiBr. This result reveals that the conducting species are predominantly ions. Primary battery has been constructed with the configuration Zn + ZnSO4 · 7H2O/92.5 PVA: 7.5 PAN: 30 wt % LiBr/PbO2 + V2O5 using the maximum conducting blend polymer, and its discharge characteristics has been discussed.