Comparative Studies on Ionic Liquid and Polymer Ionic Liquid Blend for Application in EDLCs

Abstract

In the present work, comparative studies on two ion-conducting materials, 1-butyl-3-methylimidazolium chloride (BMIMCl) as ionic liquid (IL) and polymer ionic liquid blend, are reported. For the synthesis of polymer ionic liquid blend system, BMIMCl as ionic liquid, PVDF-HFP and acetonitrile as a solvent are used. The different polymer ionic liquid blend is prepared by adopting universal solution cast technique and electrolyte sample is optimized mixing IL in the polymer by maintaining ratio 1:4. The impedance plot is observed by LCR Hi-TESTER. The optimized sample of electrolyte system shows higher ionic conductivity of the order ≈10 −3 S cm −1 . The Arrhenius behavior is found from the temperature dependence conductivity plot, giving activation energy of E a ≈ 0.073 eV. The ionic transference number is calculated for IL and optimized polymer ionic liquid blend. Electrical potential window stability is observed for IL and polymer ionic liquid blend. The fabrication of electrochemical double layer capacitors (EDLCs) is done by sandwiching ion conducting materials between two carbon electrodes. The specific capacitance of EDLC cell: AC ||(PVDF-HFP (20 wt%) + (BMIMCl) (80 wt%)|| AC and AC ||BMIMCl|| AC, gives highest capacitance value ≈116.9 and 96.5 mF cm −2 equivalent to single electrode capacitance 54.57 and 52.6 F g −1 , respectively, by cyclic voltammetry studies at 1 mV s −1 scan rate.