Simultaneous Enhancement of Energy and Power Density of Reduced Graphene Oxide by the Effect of Dispersed Metal Oxide Nanoparticles in the Electrolyte

Few-layered reduced graphene oxide (RGO) is prepared from graphite by chemical exfoliation method. In half cell, RGO electrode delivers a specific capacitance value of 41 mF cm(-2) at 0.5 mA cm(-2) in 1.0 M KOH. An attempt is made to improve the capacitance properties of RGO by widening the operating voltage window and improving the charge storage capability through the use of metal oxide nanoparticles as electrolyte additives. The specific capacitance of RGO increases to 62 mF cm(-2) and 87 mF cm(-2) when ZnO and SiOx nanoparticles were uniformly dispersed in the electrolyte, respectively, at 0.5 mA cm(-2). For a power density of 1.5 mW cm(-2), the symmetric supercapacitor assembled using ZnO and SiOx nanofluid electrolyte delivers an energy density of 2.6 mu Wh cm(-2) and 3.03 mu Wh cm(-2), respectively, which is 2.7 and 3.1 times the value of energy density obtained for symmetric supercapacitor assembled using KOH electrolyte. The nanofluid electrolytes show high stability even after 60 d and the electrochemical performance of RGO is reproducible in the aged nanofluid electrolytes. The RGO electrode shows stable cycling for the tested number of 10000 cycles in all the electrolytes.