In this study, the effect of reduced graphene oxide (rGO) on interconnected Co3O4 nanosheets and the improved supercapacitive behaviors is reported. By optimizing the experimental parameters, we achieved a specific capacitance of ~1016.4 F g-1 for the Co3O4/rGO/NF (nickel foam) system at a current density of 1 A g-1. However, the Co3O4/NF structure without rGO only delivers a specific capacitance of ~520.0 F g-1 at the same current density. The stability test demonstrates that Co3O4/rGO/NF retains ~95.5% of the initial capacitance value even after 3000 charge-discharge cycles at a high current density of 7 A g-1. Further investigation reveals that capacitance improvement for the Co3O4/rGO/NF structure is mainly because of a higher specific surface area (~87.8 m2 g-1) and a more optimal mesoporous size (4-15 nm) compared to the corresponding values of 67.1 m2 g-1 and 6-25 nm, respectively, for the Co3O4/NF structure. rGO and the thinner Co3O4 nanosheets benefit from the strain relaxation during the charge and discharge processes, improving the cycling stability of Co3O4/rGO/NF.
Keywords: Co3O4 nanosheets; Strain relaxation; Supercapacitors; rGO.