Electrical studies on ionic liquid-based gel polymer electrolyte for its application in EDLCs

Abstract

Ionic liquid-based gel polymer electrolyte (GPE) has been synthesized using standard solution cast technique. Different weight percent of ionic liquid, 1-Butyl-3-methylimidazolium chloride (BMIMCl) and liquid electrolyte, ethylene carbonate (EC)–propylene carbonate (PC)–tetra ethyl ammonium tetra fluoro borate (TEABF4) was incorporated in polymer, poly(vinylidene fluoride-co-hexafluoro propylene (PVdF-HFP) to obtain mechanically stable gel polymer electrolyte film (GPE) having maximum conductivity of ~10−3 S cm−1 at room temperature, which is acceptable from device fabrication point of view. Potential window and ionic transference number has been obtained to examine the potential limit and ionic characteristics of optimized GPE system. Temperature dependence behavior of electrical conductivity curve follows Arrhenius nature in the temperature range of 303–373 K. Pattern of dielectric constant and its loss as a function of frequency and temperature have been studied and is being explained on the basis of electrode interfacial polarization effect. Frequency-dependent conductivity spectra obey the Jonscher’s power law. Further, optimized composition of GPE has been tested successfully for its application in supercapacitor fabrication with activated charcoal as an electrode material. Maximum specific capacitance of 118.6 mF cm−2 equivalent to single electrode specific capacitance of 61.7 F g−1 have been observed for the optimized GPE film.