EDLC supercapacitor with enhanced charge-discharge cycles designed from plasticized biopolymer blend electrolytes: Biomaterials will be the future of energy storage devices

The challenge faced by EDLC in terms of being used as an alternative to batteries is their energy density. The present work exhibits an EDLC device with high energy density and long charge-discharge cycles. A range of techniques have been used to inspect the structural and electrochemical properties of the films. The interaction occurred among different components of the plasticized CS:PVA-based electrolytes and were analyzed using FTIR approach. The band at 2039.59 cm⁻¹ assigned to SCN anion displayed distinguishable shifting in plasticized systems. Electrochemical impedance spectroscopy was performed on the films to study the electrical and dielectric properties. It was found from the impedance analysis that glycerol plasticizer is crucial to reduce the bulk resistance of electrolytes. The AC conductivity spectra were used to separate the DC conductivity contribution. Dielectric properties established that charge storage, associated with the dielectric constant, is double that of the loss phenomena associated with dielectric loss. The shift of the loss tangent peak to a higher frequency with increasing plasticizer content indicates improved ion transport. The contribution of high ion fraction (t_ion = 0.947) and electrochemical stability (breakdown voltage = 2.73 V) of the films were justified via TNM and LSM techniques, respectively. The nearly rectangular pattern of CV plot and practically ideal behavior of charge-discharge indicates non-Faradaic process for the charge storage mechanism. The average value of important parameters such as ESR (≤38 Ω), specific capacitance (93.34 F/g), efficiency (98.9 %), energy density (12.96 Wh/kg) and power density (2054.05 W/kg) over 5000 cycles are evidence for high performance of the fabricated EDLC device.