Porous α-Fe₂O₃ nanowire arrays coated with a layer of carbon shell have been prepared by a simple hydrothermal route. The as-synthesized products show an excellent electrochemical performance with high specific capacitance and good cycling life after 9000 cycles. A solid state asymmetric supercapacitor (ASC) with a 2 V operation voltage window has been assembled by porous α-Fe₂O₃/C nanowire arrays as the anode materials, and MnO₂ nanosheets as the cathode materials, which gives rise to a maximum energy density of 30.625 Wh kg−1and a maximum power density of 5000 W kg−1 with an excellent cycling performance of 82% retention after 10,000 cycles.
Keywords: asymmetrical supercapacitor; energy storage device; long cycling life; α-Fe2O3/C.