The study of ion transport parameters associated with dissociated cation using EIS model in solid polymer electrolytes (SPEs) based on PVA host polymer: XRD, FTIR, and dielectric properties

Abstract

Electrical impedance spectroscopy (EIS) model is used to determine ion transport parameters. The transport parameters such as mobility, carrier density and diffusion coefficient of ions are the subject of great interest. The solution cast method is used to fabricate SPEs using polyvinyl alcohol (PVA) loaded with different amounts of sodium iodide (NaI). XRD deconvolution is used to separate the crystalline phase from amorphous phase. The degree of crystallinity is reduced with an increased amount of NaI. FTIR is used to investigate the polymer/salt interactions. To find out the circuit element, the Nyquist plots of impedance results are fitted with EEC modeling. The bulk resistance obtained from the EEC modeling is used to determine DC conductivity. At room temperature the maximum conductivity of 2.41×10-4S/cm is measured. The regions belong to the electrode polarization (EP) effect are distinguished form the spectra of dielectric constant and dielectric loss. Due to the buildup of charge carriers, the dielectric constant and loss are observed to be high at the low-frequency region. Obvious peaks are appeared in the tanδ and M“ spectra at high salt concentrations. Shifting of the tanδ peaks to the high frequency region are detected. The incomplete circular arc of the argand plot is shown the non-Debye relaxation. It is found that with increasing frequency, AC conductivity increased. The regions belong to the EP and DC contributions are differentiated in the AC spectra.