Steps towards the ideal CV and GCD results with biodegradable polymer electrolytes: Plasticized MC based green electrolyte for EDLC application

Abstract

Advanced materials are a primary focus of many research groups for applications in energy storage devices. Natural polymers, as a branch of advanced materials, are currently a hot topic to produce clean energy and reduce microplastics problems in the ocean and their potential harm to human health through ingestion. A novel biodegradable green polymer electrolyte was selected for energy storage in the current investigation. The MC polymer was impregnated with a fixed weight percent (40 %) of sodium thiocyanate (NaSCN) and different amount of glycerol to produce flexible films of solid polymer electrolytes (SPEs) using solution casting method. The XRD test reveals that the lowest degree of crystallinity is present in the most conductive electrolyte with increasing plasticizer. According to the electrochemical impedance spectroscopy (EIS) results, the sample that was incorporated with 50 % glycerol displayed the highest conductivity. FTIR was employed to observe the interaction of electrolyte components. Ions were found to be the primary species contributing to conduction, with transference numbers of 0.958 and 0.042 for ions (tion) and electrons (te), respectively. The results obtained from the linear sweep voltammetry (LSV) data confirm that the sample can withstand a voltage of approximately 2.54 V. This voltage level is suitable for extensive practical applications. The shape of the CV pattern was almost comparable to an ideal rectangular shape at low scan rates. A slight increase in the internal resistance (ESR) of the EDLC cell was observed, which increased from 59 to 68 Ω. The battery cycler was used to charge and discharge the designed EDLC device and some key parameters, including capacitance (110 F.g−1), energy density (15 Wh.Kg−1), and power density (1300 W.Kg−1) were determined from the discharge curve. Ultimately, based on the study of the assembled cell, it has been suggested that supercapacitors have emerged as potential alternative to replace environmentally harmful Li-ion batteries in advancing green energy.