Electrical double layer supercapacitors based on graphene nanoplatelets electrodes in organic and aqueous electrolytes: Effect of binders and scalable performance

Abstract

The effect of some commercial binders, carboxymethyl cellulose, polyvinylidene fluoride, modified styrene butadiene copolymer and vinylidene fluoride-hexafluoropropene copolymer on the capacitive performance of symmetric Graphene nanoplatelets (GnP) electrodes has been investigated in both organic and aqueous electrolytes. Surface area, pore size distribution, resistance and wetting behaviour of the electrodes have been measured and the effects of these factors have been studied to rationalise their electrical double layer capacitor (EDLC) performances. The most homogeneous distribution and lowest aggregation of the GnP electrode is obtained with CMC binder. Among the electrodes, it has also shown better capacitive behaviour in both aqueous and organic electrolyte due to its higher surface area, and higher mesoporous and microporous distributions than the other electrodes. To investigate scalable performance of the GnP electrodes, CMC binder electrodes have been scaled up from coin cell to pouch cell size. The coin cell electrodes showed higher capacitance than the pouch cell up to current densities of 50 A g(-1). The pouch cell has exhibited the higher capacitance at 50 A g(-1) and better capacitance retention, which shows that the pouch cell is a better charge storage device than coin cell at high current densities.