Green biopolymer and plasticizer for solid electrolyte preparation: FTIR, electrochemical properties and EDLC characteristics

Abstract

In this study a green electrolyte was developed by incorporating methylcellulose (MC) polymer with potassium thiocyanate as ion provider and plasticized with glycerol to enhance salt dissociation. The purpose of glycerol addition was to improve DC conductivity and to enhance the performance of an electric double-layer capacitor (EDLC) device. The electrochemical and structural characteristics of the green electrolyte were examined. The broadening of the FTIR bands and a decrease in intensity indicated the interaction between the electrolyte components. The suitability of the electrolyte films for device applications was confirmed by measuring ionic conductivity using electrochemical impedance spectroscopy (EIS) skills. A significant amount of charge was concentrated at the electrode–electrolyte interface because of the high dielectric constant of the electrolyte. The loss tangent (tan δ) and modulus (M“) spectra obtained from electrical impedance spectroscopy showed distinct peaks associated with ion relaxation processes. The results of the transference number measurement (TNM) experiment indicated that ions were more influential than electrons. The stability of the film under different voltage conditions was evaluated using the linear sweep voltammetry (LSV) method. The performance of the EDLC was determined through cyclic voltammetry (CV) and charge–discharge evaluations. The CV pattern of the device at low scan rates showed a non-Faradaic mode of charge storage with a nearly rectangular shape. The newly constructed EDLC exhibited an initial capacitance per unit mass of 79F/g, a utilization efficiency of 87%, a power density of 1950 W/kg, and an energy storage density of 12.1 Wh/kg.