Construct hierarchical electrode with NixCo3-xS4 nanosheet coated on NiCo2O4 nanowire arrays grown on carbon fiber paper for high-performance asymmetric supercapacitors

In order to boost the energy density of supercapacitors, the strategy of using advanced pseudo-capacitive electrode and asymmetric device architecture is feasible and effective. Herein, we report a significant advance in the design and synthesis of a new hierarchically nanostructures with a series of controllable Ni/Co molar ratios of NixCo(3-x)S(4) (i.e., NiCo2S4 and Ni2CoS4) nanosheets coatings have in situ grown on NiCo2O4 nanowires arrays on a flexible carbon fiber paper (CFP). Remarkably, the hybrid Ni2CoS4@NiCo2O4 composite electrode delivers the highest discharge gravimetric capacitance of 1501 F g(-1), and areal capacitance of 1.86 F cm(-2) at 1 mA cm(-2). Furthermore, coupled with nitrogen-doped carbon xerogels anode, we have fabricated a 1.6 V asymmetric supercapacitor (Ni2CoS4@NiCo2O4// nitrogendoped carbon xerogels), such device delivers a maximum energy and power densities of 32.2 Wh kg(-1) and 2.5 kW kg(-1) in 1.0 M KOH electrolyte, respectively, and an excellent cycling stability (similar to 87.6% retention after 10,000 cycles). (C) 2017 Elsevier B.V. All rights reserved.