Preparation and characterization of PVP-based polymer electrolytes for solid-state battery applications

Sodium ion conducting polymer electrolyte films based on poly(vinyl pyrrolidone) (PVP) were prepared using solution casting technique. Structural characterization was performed using X-ray diffraction (XRD) technique. Increase in amorphous phase with the increase of dopant concentration was observed. Temperature dependence of electrical conductivity was performed using AC impedance analyzing technique in the frequency range of 0.1 KHz to 1 MHz. Activation energy values were evaluated, as well. Optical absorption studies were carried out in the wavelength range 200–600 nm. Absorption edge, direct band gap, and indirect band gap values were also evaluated. Optical absorption edge and optical band gap (both direct and indirect) showed decreasing trend with increasing the concentration of the dopant. Dominant conducting species in the present electrolyte system was determined using Wagner polarization technique and dominant conducting species were found to be ions rather than electrons. Solid-state batteries were developed using the present solid polymer electrolyte system and discharge characteristics over the load of 100 kΩ. Cell parameters, e.g., open circuit voltage, short circuit current, current density, power density were evaluated, too. Among these cells, the cell made up of PVP/NaI (70/30) ratio for electrolyte was found to be more stable than the other two cells PVP/NaI (90/10) and (80/20) ratios and the obtained results were comparable with the results achieved by other studies.