Effect of ionic liquid on plasticized CS-PVP-NaI based bio-polymer blend electrolytes: Structural, thermal, dielectric and ion transport properties study

Abstract

The effect of imidazolium based ionic liquid (IL), 1-ethyl-3-methylimidazolium methyl sulfate [EMIM][MeSO4] on structural, thermal, dielectric and ion transport properties of Chitosan (CS)-poly(vinyl) pyrrolidone (PVP)-polyethylene glycol (PEG)-sodium iodide (NaI) based bio-polymer blend electrolyte (BPBE) films were studied using XRD, SEM, optical microscopy (OM), ATR-FTIR, TGA and impedance spectroscopic techniques. The BPBE films based on CS-PVP-PEG-NaI-IL (x = 0, 10, 20, 30, 40, 50, 60) have been prepared using solution cast method. The sample 50IL has been found to have maximum ionic conductivity ∼ 6.10 × 10-4 S/cm at 30 °C. The XRD results reveal that the BPBE films are semi-crystalline in nature and amorphousness is optimum for 50IL. ATR-FTIR analysis reveals the interaction between the functional groups of bio-polymer electrolyte with the cations/anions of IL/salt. TGA analysis shows that the BPBE films were decomposed in multi steps. Optical microscopy results show the reduction in surface roughness with increasing IL content. This result also confirmed by SEM analysis. LSV and CV measurements were carried out for knowing the electrochemical stability window (ESW). Ionic transference number (ITN) measurement shows the 50IL sample has ITN ∼ 0.98.