Study of impedance and solid-state double-layer capacitor behavior of proton (H+)-conducting polymer blend electrolyte-based CS:PS polymers

A series of proton-conducting polymer blend electrolytes (PBEs) were prepared using solution casting techniques. Chitosan (CS) and starch of potato (PS) were blended and doped with various amounts of ammonium fluoride (NH4F). The highest DC conductivity was found to be 1.38 × 10−3 S/cm for the sample incorporated with 40 wt.% NH4F salt using electrical impedance spectroscopy (EIS). A good complex formation between the polymer blends and the doped salt was confirmed from the morphology of the sample’s surface using field emission scanning electron microscope (FESEM). The crystalline peak broadening and intensity reduction of CS:PS polymer blend with the increasing salt concentration was observed in the X-ray diffraction (XRD) analysis. The type of charge carrier in the PBEs was examined via transference number measurements (TNM), and the dominancy of ion was approved. The extent of electrochemical stability of electrolyte was determined to be up to 1.78 V using linear sweep voltammetry (LSV). The specific capacitance of 6.85 F/g was obtained from cyclic voltammetry (CV) measurement. The rechargeability of the electric double-layer capacitor (EDLC) exhibited stability up to 100 cycles with average specific capacitance of 4.1 F/g. Three criteria were determined, which are internal resistance, energy density, and power density (550 Ω, 0.57 Wh/kg, and 155 W/kg, respectively) of the EDLC at the first cycle.