Supercapacitors from Activated Carbon Derived from Banana Fibers

Carbon materials were synthesized from banana fibers by treating the fibers with pore-forming substances such as ZnCl2 and KOH with an intention to improve the surface area and their electrochemical performance as electrical double-layer capacitor electrodes. The performance of these materials was studied in a neutral electrolyte for the first time. There has been a substantive increase in the specific surface area of the treated carbon material because of the effective pore generations. The structural and surface properties of the prepared carbon materials were studied using scanning electron microscopy and N2 adsorption/desorption studies. The surface area of the 10% ZnCl2 treated sample was found to be 1097 m2/g. The electrochemical properties of untreated and porogen treated carbons were evaluated by using cyclic voltammetry and galvanostatic charge−discharge studies, and the specific capacitance as high as 74 F/g in 1 M Na2SO4 neutral electrolyte was obtained for 10% ZnCl2 treated carbon as determined by constant current charge−discharge studies. The system showed excellent cyclability with a Coulombic efficiency of ∼88% at a high current density of 500 mA/g for 500 cycles. The electrochemical performance of the high surface area carbon in the neutral electrolyte medium is significantly high, and the reasons are discussed.