Fabrication of high performance energy storage EDLC device from proton conducting methylcellulose: dextran polymer blend electrolytes

This paper reports Methylcellulose:Dextran (MC:Dex) polymer blend based electrolyte system with NH4I salt for electrical double layer capacitor (EDLC) application. The structural and electrochemical properties of the electrolyte systems were investigated using X-ray diffraction (XRD), Fourier transformed infra-red (FTIR) spectroscopy, Field emission scanning electron microscope (FESEM), impedance spectroscopy, transference number measurement (TNM) and linear sweep voltammetry (LSV). The FTIR studies revealed the complexation between MC:Dex polymer blend and NH4I salt. The reduction in the crystallinity of MC:Dex polymer blend with the increasing salt concentration was observed in XRD analysis. The electrolyte system was observed to be predominantly ionic in nature. The electrolyte composition with 40 wt.% of NH4I showed the maximum ionic conductivity as 1.12 × 10−3 S/cm with electrochemical stability window of 1.27 V. The highest conducting composition of the electrolyte system was used to prepare EDLC with activated carbon electrodes. The EDLC exhibited initial specific capacitance as 79 F/g, energy density as 8.81 Wh/kg and power density as 1111.1 W/kg at a current density of 0.2 mA/cm2.