Co3O4/carbon nano-onions composite as supercapacitor electrode and its excellent electrochemical performance

An ionic liquid derived Co3O4/carbon nano-onions composite has been prepared by carbothermal reduction followed by oxidation. The introduction of carbon nanoonions improves the conductivity and structural stability of Co3O4 electrode material. Electrochemical measurements indicate that the redox reversibility is significantly improved. The Co3O4/carbon nano-onions composite shows a large specific capacitance of 402.35 F g-1 at a current density of 0.5 A g-1. After 9 000 cycles, the specific capacitance retention remained 76% at 1 A g-1. The as-prepared Co3O4/carbon nano-onions composite delivers superior capacitive performance with good rate capability, large specific capacitance, and excellent cyclic performance, showing great application potential for high-performance electrochemical supercapacitors.