Excellent Electrochemical Performance Hierarchical Co3O4@Ni3S2 core/shell nanowire arrays for Asymmetric Supercapacitors

Abstract

Three-dimensional hierarchical Co3O4@Ni3S2 core/shell nanowire arrays were designed and fabricated on nickel foam via a facile two-step route for supercapacitor applications. Compared with the pristine Co3O4 nanowire arrays and Ni3S2 nanosheets, the hierarchical nanostructure demonstrates much more excellent capacitive behaviors. The Co3O4@Ni3S2 electrode exhibited an ultrahigh specific capacitance of 1710Fg−1 at 1Ag−1 and 1474Fg−1 at 10Ag−1. An asymmetric supercapacitor based on Co3O4@Ni3S2 core/shell nanowire arrays on nickel foam as the positive electrode and activated carbon (AC) as negative electrode was successfully assembled. A specific capacitance of 126.6Fg−1 at 1Ag−1 (retaining 83.5% capacity after 5000 cycles at a current density of 2Ag−1) and an outstanding energy density of 44.9 Wh kg−1 was achieved. The remarkable electrochemical properties could be attributed to the unique hierarchical architectures of Co3O4@Ni3S2 core–shell nanowire arrays on 3D on nickel foam and a rational combination of two electrochemical pseudocapacitor materials. The results indicate that our asymmetric supercapacitors have great potential in energy storage device applications.