Investigation of ionic liquid-doped ion conducting polymer electrolytes for carbon-based electric double layer capacitors (EDLCs)

Abstract

Ionic liquid-based poly(vinyl alcohol) (PVA)/ammonium acetate (CH3COONH4) ion conducting polymer electrolytes are prepared by solution casting technique. Ionic liquid, 1-butyl-3-methylimidazoliumtrifluoromethanesulfonate (BmImTf) is then added to increase the ionic conductivity of polymer electrolytes by reducing the glass transition temperature (Tg).It is found that ionic conductivity of polymer electrolytes increases with temperature. The polymer electrolytes are found to obey the Vogel–Tamman–Fucher (VTF) rule in the conduction mechanism which is related to free volume model. Subsequently, two symmetrical electrodes containing activated carbon, carbon black and carbon nanotubes (CNT) are prepared through the dip coating method. Electric double layer capacitors (EDLCs) are then assembled using these electrodes and polymer electrolytes. Excellent electrochemical properties such as higher specific capacitance were obtained for EDLC comprising ionic liquid–doped polymer electrolytes. Power density of 18.37kWkg−1 was obtained for the EDLC containing the most conducting ionic liquid–added polymer electrolyte.