▎ 摘　　要

Metal oxide decorated graphene nanosheets have gathered much attention due to their potential applications in electrochemical energy storage devices particularly in supercapacitors. Attempts are in progress to develop highly efficient graphene nanocomposites via facile and scalable method for practical applications. Here, we demonstrate a facile and scalable chemical route to synthesis ultrafine (similar to 10 nm) crystalline cobalt oxide (Co3O4)/reduced graphene oxide (RGO) nanocomposites through chemical decomposition of cobalt hexacyanoferrate complex directly on RGO surface. X-ray diffraction pattern reveals the formation of highly crystalline Co3O4 nanoparticles RGO surface without any heat treatment. The ultrafine Co3O4/RGO nanocomposites showed a high specific capacitance of 784 F g(-1) at 1 A g(-1) in alkaline medium in three electrode configuration. The asymmetric supercapacitor device was fabricated using RGO as anode and Co3O4/RGO as cathode. The fabricated asymmetric device exhibits a remarkable specific capacitance of 245 F g(-1) with high energy and power density of 16.6 Wh kg(-1) and 3473 W kg(-1), respectively. Also, the fabricated pouch cell exhibits an excellent electrochemical stability of > 94% after 20,000 cycles of charge-discharge.