Electrical and structural characterization of PVA/PEG polymer blend electrolyte films doped with NaClO4

Abstract

A solid polymer blend electrolyte system based on polyvinyl alcohol (PVA) and polyethylene glycol (PEG) complexed with NaClO4 was prepared using solution cast technique. The structural properties of these electrolyte films were examined by X-ray diffractrometry (XRD) studies. The XRD data revealed that the amorphous domains of polymer blend matrix increased with increase of sodium salt concentration. The complexation of the salt with the polymer blend was confirmed by Fourier transform infrared (FTIR) studies. DC conductivity of the films was measured in the temperature range 303–398 K. The electrical conductivity increased with increasing dopant concentration, which is attributed to the formation of charge transfer complexes. The electrolyte exhibited the highest room temperature conductivity 2.41 × 10−6 S cm−1 at 30 % of NaClO4 salt concentration. The polymer complexes exhibited Arrhenius-type dependence of conductivity with temperature. In the temperature range studied, two regions with different activation energies were observed. Electrochemical cells of configuration Na/(PVA + PEG + NaClO4)/(I2 + C + electrolyte) were fabricated and the discharge characteristics of these cells were studied under a constant load of 100 K. Several cell parameters associated with the cells were evaluated and compared with earlier reports. UV-VIS absorption spectra in wavelength region 200–600 nm were used to evaluate the optical properties like direct band gap, indirect band gap and absorption edge. The optical band gaps decreased with increasing sodium ion concentration. This suggests that NaClO4 is a good dopant to improve the electrical properties of PVA + PEG polymer blend electrolytes.