EIS and FTIR approaches to study the ion transport parameters and relaxation dynamics of Na+1 ion in SPE based on MC polymer inserted with sodium salt

Abstract

In this work deep insights on ion transport parameters based on EIS and FTIR were presented. MC based biopolymer was used as the host material to prepare solid polymer electrolyte (SPE). The XRD equipment was used to study the structural changes happening in the SPE films upon addition of various rate of NaSCN salt. The polymer-salt interactions were observed from the shifting and changing of intensity of FTIR transmittance peaks. The EIS plots were fitted with EECs to detect the electrical properties of the films. Transport parameters including number density (n), mobility (μ) and diffusion coefficient (D) were evaluated using impedance and FTIR methodologies. The percentage of free ions was found to influence the transport parameters utilizing FTIR approach. The maximum DC conductivity of 3.6 × 10−6 Scm−1 was obtained for the MC film incorporated with 40 wt% of NaSCN salt. The temperature variation of DC conductivity follows Arrhenius behavior model. The dielectric properties of the films were studied at ambient temperature. The effects of temperature on dielectric properties were examined on the highest conducting sample. The relaxation processes were analyzed in terms of loss tangent and electric modulus. Broad peaks of M'' pattern and tanδ plot are marks for non-Debye type relaxation of Na+ ions. The ion conduction mechanisms as a complicated subject in SPEs were focused in this work. The noticeable results achieved from the dielectric properties and electric modulus indicated the coupled motion between cations of the dissolved salt and polymer segmental motions. The transport of ions followed Arrhenius model in which polymer chains assist ion jumping.