Self-assembled zinc oxide nanocauliflower and reduced graphene oxide nickle-foam based noval asymmetric supercapacitor for energy storage applications

Metal oxide nanostructures exhibit excellent properties, which make them a promising candidate for a broad range of green energy applications, including energy storage. In this work, asymmetric supercapacitor has been designed by using ZnO@stainless steel (SS) nanocauliflower as positive (Cathode) electrode and reduced graphene oxide rGO@Ni electrodes negative (Anode) electrode. The thin film electrode of ZnO was synthesized by reactive DC magnetron sputtering whereas rGO electrode was deposited via electrodeposition process. Furthermore, electrochemical kinetics of deposited thin film electrodes were done in 6 M aqueous KOH electrolyte solution. This novel supercapacitor rGO@Ni//ZnO@SS shows better capacitive performance than other nanostructured metal oxides. The as-fabricated ASCs exhibit comparably good electrochemical performance, including good capacitive values (within the range of 0-1.4 V) and long cycle stability (89.5% after 5000 cycles). The ASC offers good energy density of 23 Wh/kg at an optimum power density of 156 W/kg in 6 M KOH aqueous electrolyte, which shows comparably better results than the other reported ASCs. The excellent performance of nanostructured ASCs has momentous potential application in electric vehicles and in portable electronics.