Electrical, transport, and optical properties of a novel PVB-NaNO3 complexed solid polymer electrolyte thin-films for solid-state battery

Abstract

The thin films of solid polymer electrolyte were made using Polyvinyl Butyral (PVB), and Sodium Nitrate (NaNO3) of different compositions, using Methanol as a solvent, by ‘solution casting technique. Then, this Polymer electrolyte thin films were checked using different characterization techniques like UV–visible spectroscopy, FTIR, XRD, and DC conductivity studies. The electrolyte sample with 30 wt% of NaNO3 showed maximum conductivity of 1.52x10-11 S cm−1 at 338 K and 4.01x10-8 Scm−1 at 393 K. The Cole-Cole graphs of AC conductivity were plotted using the impedance spectroscopy data, for PVB70%: NaNO330% concentration which showed the conductivity of 7.07x10-10 Scm−1 at 333 K and 6.54x10-7Scm−1 at 393 K. Using Wagner’s polarization technology, the carriers which led to the conduction of charge transport in the electrolyte films were found. It was identified that the ions were predominantly the charge transport carriers. The absorption spectra for the samples were calculated using a UV Spectrometer in the wavelength range of 250–900 nm. In Pure PVB polymer, the optical absorption is very less and this increases gradually when the salt NaNO3 concentration is increased. For the combination of PVB 70%: NaNO3 30% concentration, maximum absorption is seen at the wavelength 530 nm. For the same combination, there was a minimum absorption edge and it shifts towards the maximum energy above this concentration. The photon energy range lies between 2.4 eV and 1.6 eV, which shows that the band gap of the doped samples decreases.