Optical, electrical and discharge profiles for (PVC + NaIO4) polymer electrolytes

A sodium ion conducting polymer electrolyte based on poly (vinyl chloride) (PVC) complexed with NaIO4 was prepared using a solution-cast technique. Optical properties such as direct and indirect optical energy gap, and optical absorption edge were investigated in pure and doped PVC films from their optical absorption spectra in the 200–600 nm wavelength region. The direct optical energy gap for pure PVC lies at 3.14 eV while it ranges from 2.60 to 3.45 eV for different composition doped films. Similar behavior was observed for the indirect optical energy gap and absorption edge. It was found that the energy gaps and band edge values shifted to higher energies on doping with NaIO4 up to a dopant concentration of 10 wt%. Measurements of ionic conductivity and transference number were made to investigate the order of conductivity and charge transport in this polymer electrolyte. Transference number values show that the charge transport in this polymer electrolyte is predominantly due to ions (tion = 0.93). The conductivity increases with increase in concentration of the salt and with temperature. Using this electrolyte, cells were fabricated and their discharge profiles were studied under constant load. Miscibility studies were performed using X-ray diffraction (XRD) and Fourier Transform Infrared analysis (FT-IR) measurements.