Hierarchical NiCo2S4@CoMoO4 core-shell heterostructures nanowire arrays as advanced electrodes for flexible all-solid-state asymmetric supercapacitors

In order to meet the application requirements of portable and wearable devices, the high-efficiency energy storage units with high energy density, high power density and long cycle life are urgently needed. In this work, we have successfully fabricated novel flexible electrode comprising NiCo2S4@CoMoO4 core-shell nanowire arrays on carbon cloth via a facile three-step hydrothermal process. Benefiting from the unique hierarchical structure and their synergistic effects between CoMoO4 and NiCo2S4, the supercapacitor electrode realizes a fast electron and ion transfer, a large electroactive surface area and superior conductivity. As a result, the NiCo2S4@CoMoO4 electrode exhibits superior performances with an outstanding specific capacitance of 2118.8 F g(-1) at 1 Ag-1 and an excellent rate capability of 81.6% at 20 A g(-1). After 5000 cycles, the NiCo2S4@CoMoO4 electrode shows an excellent cyclic performance with 88.6% capacity retention. The excellent performance of electrode is also confirmed by assembling all-solid-state asymmetric supercapacitor, which delivers a high energy density of 66.6 Wh kg(-1) as well as the maximum power density of 16 kW kg(-1). This work demonstrates that the NiCo2S4@CoMoO4 electrode provides a promising material for the energy storage applications in the future. (C) 2018 Published by Elsevier B.V.