Fabrication and characterization of electrochemical double layer capacitors using ionic liquid-based gel polymer electrolyte with chemically treated activated charcoal electrodes

The present investigation deals with electrochemical double layer capacitors (EDLCs) made up of ionic liquid (IL)-based gel polymer electrolytes with chemically treated activated charcoal electrodes. The gel polymer electrolyte comprising of poly(vinylidine fluoride-co-hexafluropropylene) (PVdF-HFP)-1-ethyl-2,3-dimethyl-imidazolium-tetrafluroborate [EDiMIM][BF4]-propylene carbonate (PC)-magnesium perchlorate (Mg(ClO4)(2)) exhibits the highest ionic conductivity of similar to 8.4 x 10(-3) S cm(-1) at room temperature (similar to 20 A degrees C), showing good mechanical and dimensional stability, suitable for their application in EDLCs. Activation of charcoal was done by impregnation method using potassium hydroxide (KOH) as activating agent. Brunauer-Emmett-Teller (BET) studies reveal that the effective surface area of treated activated charcoal powder (1,515 m(2) g(-1)) increases by more than double-fold compared to the untreated one (721 m(2) g(-1)). Performance of EDLCs has been tested using cyclic voltammetry, impedance spectroscopy, and charge-discharge techniques. Analysis shows that chemically treated activated charcoal electrodes have almost triple times more capacitance values as compared to the untreated one.