Design and fabrication of interconnected 2D/3D NiS/Ni3S4 composites supercapacitor electrodes for energy storage applications

Innovative materials with excellent cyclic performance become the mantra for energy storage. In this report, a novel 2D/3D NiS/Ni3S4 composite was fabricated by a one-pot hydrothermal process, in which 3D hierarchical microspheres were anchored in or covered by the interconnected 2D nanosheets. Phase-property relationship of NiS/Ni3S4 was established through combining characterization analysis with electrochemical tests. With the favorable particle size and composition, the NiS/Ni3S4 composites exhibited a high specific capacitance of 1856 Fg(-1) and good capacitance retention of 84.8% at a current density of 1 Ag-1 after 5000 charge-discharge cycles. For proving the practical application, the asymmetric supercapacitor device has been fabricated and achieved a maximum energy density of 66.3 Whkg(-1) at 2 Ag-1 with excellent device stability (99.5%) over 5000 cycles. Our results indicate that the interconnected 2D/3D NiS/Ni3S4 composites can be a promising electrode material for supercapacitor-based energy storage applications.