Chitosan-PVA-AgNO3-Ionic Liquid Based Solid Electrolyte Membranes for Supercapacitor Applications: Structural, Thermal and Ion Transport Studies

Abstract

In this work, the effect of 1-ethyl-3-methylimidazolium methylsulfate ([EMIM][MeSO₄]) ionic liquid (IL) on the structural, dielectric, and ion transport properties of plasticized [Chitosan-PVA-PEG-AgNO₃] based biopolymer blend electrolyte (BPBE) membranes were analysed. XRD and SEM analysis reveals that the amorphous nature increases with IL incorporation, while FT-IR confirms IL/salt–biopolymer-polymer complexation. TGA demonstrates multi-step thermal decomposition phenomenon. The sample containing 30 wt% IL has the maximum ionic conductivity of 1.12 × 10^− 3 S cm⁻¹ at 30 °C with the lowest activation energy and transference number of 0.99. Temperature dependent electrical conductivity, dielectric relaxation behaviour, frequency-dependent conductivity and ion dynamics have been analysed. Supercapacitor has been fabricated using the sample having maximum ionic conductivity and its performance has been analysed using cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD) and life cycle test. CV results show the electric double layer capacitor (EDLC) type conduction mechanism. Fabricated supercapacitor exhibits the specific capacitance of 144 F g^− 1, an energy density of 16 Wh kg^− 1, and power density of 145 W kg^− 1 along with coulombic efficiency 95% at the current density of 0.32 A g^− 1. Life cycle for 3600 cycles of charge-discharge demonstrates excellent stability with capacity retention of 94% at current density of 0.46 A g^− 1.