Electrical conductivity characterization of polyacrylonitrile-ammonium bromide polymer electrolyte system

Abstract

A new proton-conducting polymer electrolyte based on polyacrylonitrile (PAN) doped with ammonium bromide (NH4Br) has been prepared using solution casting technique. The complexation of NH4Br with PAN polymer has been studied using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The differential scanning calorimetry (DSC) thermograms of PAN with NH4Br electrolyte membrane show the decrease in glass transition temperature (T g). This reduction of T g of membrane reveals the increase of segmental motion of polymer electrolyte. The ionic conductivity of the prepared polymer electrolyte has been found by ac impedance spectroscopic analysis. The maximum ionic conductivity (2.5 × 10−3 S cm−1) has been obtained for 30 mol% NH4Br-doped PAN polymer electrolyte. The temperature-dependent conductivity of the polymer electrolyte follows an Arrhenius relationship. The dielectric spectra show low frequency dispersion. The relaxation time (τ) has been calculated from loss tangent spectra (tan δ). Ionic transference number measured has been found to be in the range of 0.92–0.99 for all the polymer electrolyte system. The result reveals that the conducting species are predominantly ions. Using the maximum ionic conducting polymer electrolyte, the primary proton-conducting battery with configuration Zn+ZnSo4·7H2O/70 PAN:30 NH4Br/PbO2 + V2O5 has been fabricated, and its discharge characteristics have been studied.