Studies on starch based magnesium ion conducting biopolymer blend electrolytes for electric doulbe layer capacitors coupled with bio-activated carbon electrodes

Solid biodegradable polymer blend electrolytes have been prepared along with magnesium nitrate salt using solution casting technique. The X-ray diffraction analysis confirms the increase in amorphous nature of the prepared polymer electrolytes by blending PVDF-HFP with starch. The FTIR spectra reveal the various vibrational frequencies of hydroxyl, carbonyl and carboxyl group of polymer electrolytes. The maximum ionic conductivity value is observed for 15% of magnesium nitrate doped system at ambient temperature. Thermal studies are also carried out for higher conducting film from room temperature to 600˚C to determine glass transition temperature and decomposition temperature of the electrolyte. Electrochemical measurements have been performed for higher conducting electrolyte to determine the electrochemical behaviour. It shows the potential window of -0.5 to 0.4 V with equal range of oxidation and reduction peaks that confirms the pseudo-capacitive nature. The charge–discharge studies are observed with current range from 0.2-2 mA and these results indicate the prepared biopolymer electrolytes are suitable for energy storage applications.