High–rate electrochemical capacitors from highly graphitic carbon–tipped manganese oxide/mesoporous carbon/manganese oxide hybrid nanowires

Abstract

In this paper, using manganese oxide as an example, we report the successful design and synthesis of a novel one-dimensional highly graphitic carbon-tipped manganese oxide/mesoporous carbon/manganese oxide hybrid nanowire. The unique structure significantly improves the conductivity of metal oxide materials, which is a key limitation in pseudocapacitors. The hybrid nanowire with optimal carbon content, when applied as an electrode, exhibits superior capacitive properties in 1 M Na₂SO₄ aqueous solution, such as high specific capacitance (266 F g⁻¹ at 1 A g⁻¹), excellent rate capability (56.4% capacity retention at 60 A g⁻¹) and outstanding cycling stability (without degradation after 1200 cycles). The energy densities achieved can be as high as 20.8 W h kg⁻¹, at a power density of 30 kW kg⁻¹. The results demonstrated that the manganese oxide in our hybrid nanomaterial was efficiently utilized with the assistance of the highly conductive graphitic carbon-tipped mesoporous carbon shell. It is reckoned that the present low-cost novel hybrid nanowire can serve as a promising electrode material for supercapacitors and other electrochemical devices.