Abstract
To supplement the ever increasing power demand in the present day world, supercapacitors have emerged as one of the suitable power storage devices. Redox capacitors have received a considerable attention due to factors such as high cycle ability, satisfactory specific capacitance and good stability. There are many reports on redox capacitors based on liquid electrolytes but these have several drawbacks. In this study, a magnesium chloride (MgCl 2 ) based gel polymer electrolyte was prepared and characterized for its suitability to be used in a redox capacitor. The composition, 0.1 polyacrylonitrile (PAN):0.4 ethylene carbonate (EC):0.4 propylene carbonate (PC):0.125 MgCl 2 (weight ratios) exhibits the highest room temperature conductivity of 4.08×10 -4 S cm -1 . Conductivity variation of this sample with the temperature shows Arrhenius behavior. The ionic transference number is 0.84. This shows that the GPE is an ionic conductor. Redox capacitors were fabricated with two polypyrrole (PPy) electrodes. They were characterized using Cyclic Voltammetry technique, Impedance Spectroscopy and Galvanostatic Charge Discharge test. Cycling at the scan rate of 10 mV/s within the potential window of -1.4 V to +1.4 V showed a specific capacitance of 120.35 F/g. Impedance data showed the electrochemical behavior of the device having resistive and capacitive behavior. Galvanostatic charge discharge test results exhibit average power density and energy density of 341 W/kg and 5 Wh/kg respectively.
Highlights
At present, there is a rising demand for portable power with the rapid growth of various applications including hybrid and electric vehicles, space crafts, memory backups, toys and many other devices
Due to shorter time needed for full charging, high columbic efficiency and longer life than batteries, supercapacitors are widely employed in many applications today (Simon and Gogotsi, 2008; Yan et al, 2014)
Most reports on redox capacitors are based on liquid electrolytes (Fonseca et al, 2006; Uppugalla et al, 2014)
Summary
There is a rising demand for portable power with the rapid growth of various applications including hybrid and electric vehicles, space crafts, memory backups, toys and many other devices. Redox capacitors use electrodes made by conducting polymers or transition metal oxides (Ramya et al, 2013). They derive the capacitance from the storage of charge in the electrode material in response to a redox reaction.
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