Effect of ammonium iodide on the structure and ionic conductivity of carboxymethyl cellulose-based gel polymer electrolytes for electrochemical devices

Gel polymer electrolytes show great potential for use in electrochemical devices. In this work, free standing Gel Polymer Electrolytes (GPEs) based on a non-hazardous and environment friendly material carboxymethyl cellulose (CMC) is successfully developed. The effect of doping ammonium iodide (NH4I) into carboxymethyl cellulose based polymer gel matrix has been examined for its structural, thermal, electrical, and electrochemical stability properties with the aim of prospective applications in electrochemical devices. Gel polymers films have been fabricated using the widely recognized solution casting method. The characterization of these (GPEs) has been performed employing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). An increase in the amorphous nature of the gel electrolyte films has been observed in the X-ray diffraction when the NH4I salt content increases. DSC studies also confirmed the formation of gel electrolyte system with an increased degree of amorphousness. The potentiostatic polarization studies reveal the electrolyte system to be ionic. The room-temperature conductivity is found to reach an optimum of 4.4 x 10-3 S/cm for 25 wt% salt concentration. All of these findings have been appropriately explained.