One-step electrodeposition fabrication of Ni3S2 nanosheet arrays on Ni foam as an advanced electrode for asymmetric supercapacitors

Ni3S2 nanosheet (NS) arrays on Ni foam were fabricated by a simple one-step electrodeposition strategy, and used as a kind of electrode material for asymmetric supercapacitors. The Ni3S2 NS arrays are interconnected, which can be regarded as bridges between these individual nanoparticle units. The electrochemical performances were evaluated by cyclic voltammetry and chronopotentiometry techniques in a three-electrode system. The Ni3S2 NS arrays display a specific capacitance of 773.6 F g-1 at 1 A g-1, and excellent rate property of 84.3% at 10 A g-1. The performance of the Ni3S2 NS arrays was further investigated in an asymmetric supercapacitor for potential practical application. The asymmetric supercapacitor using the Ni3S2 electrode and reduced graphene oxide electrode as positive and negative electrodes, respectively, exhibits an energy density of 41.2 W h kg-1 at 1.6 kW kg-1. When up to 16 kW kg-1, it holds 25.3 W h kg-1. These excellent electrochemical performances are attributed to the improved electronic conductivity and rich redox reaction sites from Ni3S2 NS arrays. Our results indicate that the Ni3S2 NS arrays have great potential for supercapacitors.