Characterization and charge transport properties of sodium ion conducting PEO:NaBr solid polymer electrolyte films

The study examines the effects of metal salt doping on polyethylene oxide (PEO) solid polymer electrolyte films. Sodium Bromide (NaBr) doped PEO films are prepared using a solution casting technique. The study finds that Na+ rom NaBr interacts with PEO's ether group (C-O-C) through complexation, as confirmed by Fourier Transform Infrared (FTIR) Spectroscopy. X-ray diffraction analysis reveals that NaBr reduces PEO's degree of crystallinity. The addition of NaBr improves PEO's thermal stability, as shown by thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) images show smooth surface morphology of the polymer electrolyte films. The study also finds that the polymer electrolytes are non-Debye in nature, based on dielectric studies. The highest ionic conductivity of 1.01 x 10(-5) S/cm is observed for the 12.5 wt% NaBr doped PEO, with a low activation energy of 0.246 eV. Wagner's polarization technique is used to determine the charge carrier transport numbers, and the transient ionic current technique confirmed the presence of a single ionic species in the polymer electrolyte. Overall, the study suggests that 12.5 wt% NaBr doped PEO films have appropriate electrical properties for developing charge storage devices.