Co3O4/MnO2/Co(OH)2 on Nickel foam Composites Electrode with excellent electrochemical performance for Supercapacitor

A composite electrode containing Co3O4 nanowire arrays, ultrathin MnO2 nanosheets and nano-flake-like Co(OH)2 thin films was prepared through simple hydrothermal method combined with suitable heat treatment and electro-deposition. The Co3O4 nanowire is connected to MnO2 nanosheets, and the Co(OH)2 nanosheets are coated on the MnO2 to form a complete network. The composite electrode shows a high specific capacitance of 3022.2 F/g at a current density of 10 A/g, and a satisfactory cyclic stability with 87.9% capacitance retention after 5000 cycles. An asymmetric electrode with Co3O4/MnO2/Co(OH)2 as the anode and activated carbon as the cathode was assembled by using 1 M KOH as electrolyte. Electrochemical performance of the Co3O4/MnO2/Co(OH)2 material was measured using CV, GCD and EIS in 1 mol L−1 KOH aqueous electrolyte. After charging for 20 s, two devices in series can light emitting diodes for about 3 min. The results indicated that the Co3O4/MnO2/Co(OH)2 material exhibited excellent electrochemical performance in terms of specific capacitance, cyclic stability, and charge/discharge stability, which is an appropriate material for supercapacitor.