CoO/rGO composite prepared by a facile direct-flame approach for high-power supercapacitors

In this study, CoO nanoparticles (NPs) measuring approximately 20?nm in size are successfully grown on reduced graphene oxide (rGO) layers through a facile direct-flame approach. The obtained CoO/rGO nanocomposites are applied as electrode materials and show a high specific capacitance, reaching 1615.0?F?g^?1 at a current of 1?A?g^?1 (737.5?F?g^?1 at 50?A?g^?1), and good cycling stability (88.12% retention after more than 15,000 cycles at 5?A?g^?1), which are outstanding characteristics compared with those of recently reported pseudosupercapacitors. Furthermore, an asymmetric supercapacitor (ASC) produced using CoO/rGO as a positive electrode material and activated graphene (AG) as a negative electrode achieves a high cell voltage of 1.6?V and delivers a maximum energy density of 62.46?Wh?kg^?1 at a power density of 1600?W?kg^?1. The fabrication technique is facile and represents a promising means of obtaining metal oxide/graphene composites for high-performance supercapacitors.