Chitosan-PEG-NaI based bio-polymer electrolytes: Structural, thermal and ion dynamics studies

Abstract

BPE films based on [Chitosan (CS)-PEG]-NaI were prepared using solution cast technique. The prepared electrolyte films were subjected to thermal, structure and conductivity studies using TGA, XRD, ATR-FTIR and AC impedance spectroscopic techniques. The thermal gravimetric analysis (TGA) reveals that the CS and [CS-PEG]-NaI based films decomposes in multi step. Onset decomposition temperature (T d,onset) also decreases with increasing NaI content in CS-PEG based films. The [CS-PEG]-NaI based films are thermally stable upto ∼220.2 °C. XRD result shows that CS has semi-crystalline in nature having its characteristic peak appeared at 2θ ∼ 23.1°. The % degree of crystallinity (Xc) decreases with increasing NaI content in CS-PEG based films. ATR-FTIR study confirms the interaction between bio-polymer, CS with PEG and NaI. The sample containing 40 wt%NaI shows dc conductivity value ∼7.25 × 10-4 Scm-1at 30 °C. The values of frequency exponent s for BPE films were found to be 0.68 to 0.22. Scaling of ac conductivity with respect to NaI concentration has been performed. Mobility (μ) and total number density of charge carriers (N) were estimated from loss tangent spectra.