Dielectric Modulus and Conductivity Scaling Approach to the Analysis of Ion Transport in Solid Polymer Electrolytes

Abstract

Solid polymer electrolyte films (SPEs) based on poly(methyl methacrylate) are prepared using a solution cast technique. The temperature-dependent behavior of dielectric, modulus spectra and ac conductivity has been investigated. The long tail of the real part of modulus (M 0 ) in the low frequency indicates the capacitive nature of the samples. The frequency dependence of imaginary part of modulus (M 00 ) shows a non-Debye relaxation that has been explained using the Kohlrausch-Williams-Watts stretched exponential function. The activation energy for the relaxation is almost same as the activation energy for the conduction. The relaxation time obtained from the tangent loss graph (τ δ ) is about two orders of magnitude larger than that obtained from the imaginary part of modulus graph (τ m ). The ac conductivity has been found to obey Jonscher's universal power law. Transport parameters show that addition of filler creates additional hopping sites for the charge carriers and also increases the charge carrier density. It is also observed that the higher ionic conductivity at higher temperature is due to increased thermally activated hopping rates accompanied by a significant increase in carrier concentration. The contribution of carrier concentration to the total conductivity is also confirmed from Summerfield scaling. POLYM. ENG. SCI., 60:297-305, 2020.

Reducing the Electrical Conductivity of ZnO/Ag Nanofiller for Solid Polymer Electrolytes Prepared by Laser Ablation in Polylactic Acid Solution

“…Thus, we can say that the busies condition is caused by charge accumulation and diffusion [20]. At high frequencies, welldefined peaks are obtained, signifying that the relaxation process is induced by ions dispersion process [12,14,20,30]. We also confirm that ZnO is playing a key role in the enhancement of the electrical activity.…”

“…Whereas in the imaginary part, the small value of M at low frequencies might be caused by the larger value of capacitance associated with the electrode, resulted from the large charge carriers accumulation at the electrodeelectrolyte interface [30]. Thus, we can say that the busies condition is caused by charge accumulation and diffusion [20]. At high frequencies, welldefined peaks are obtained, signifying that the relaxation process is induced by ions dispersion process [12,14,20,30].…”

“…The low frequency region is known as the busies phase when the charges and charge carriers are collected in electrode-electrolyte interface, thus it will decrease a relaxation process and enhance the dielectric constant [19]. The intermediate frequency is described as an ions diffusion process, where ions may migrate from one chain to another, hence, increases the relaxation process and decreases the dielectric constant as the ions is getting started to pairs [20]. As the result, in the final phase, the ions experience a pairing effect and disperse to another electrode which could also enhance the relaxation process with increasing frequency.…”

“…The polarization and ion migration process occur for a long frequency range following the ion diffusion process. It is indicated with an available space between the points of dielectric spectra [19,20]. Afterwards, the dispersion process is found at high frequency, where its magnitude reaches a saturation in the higher frequencys dispersive region [18].…”

“…It indicates that the busies situation at low frequencies are slightly decreased. However, the ionic conductivity remains high and shows a low conductivity relaxation [12,14,20,32].…”