One-step electrodeposited nickel cobalt sulfide nanosheet arrays for high-performance asymmetric supercapacitors

Abstract

A facile one-step electrodeposition method is developed to prepare ternary nickel cobalt sulfide interconnected nanosheet arrays on conductive carbon substrates as electrodes for supercapacitors, resulting in exceptional energy storage performance. Taking advantages of the highly conductive, mesoporous nature of the nanosheets and open framework of the three-dimensional nanoarchitectures, the ternary sulfide electrodes exhibit high specific capacitance (1418 F g-1 at 5 A g-1 and 1285 F g-1 at 100 A g-1) with excellent rate capability. An asymmetric supercapacitor fabricated by the ternary sulfide nanosheet arrays as positive electrode and porous graphene film as negative electrode demonstrates outstanding electrochemical performance for practical energy storage applications. Our asymmetric supercapacitors show a high energy density of 60 Wh kg-1 at a power density of 1.8 kW kg-1. Even when charging the cell within 4.5 s, the energy density is still as high as 33 Wh kg-1 at an outstanding power density of 28.8 kW kg-1 with robust long-term cycling stability up to 50 000 cycles.