ACF/NiCo2S4 honeycomb-like heterostructure material: Room-temperature sulfurization and its performance in asymmetric supercapacitors

Abstract Transition metal sulfide, especially NiCo 2 S 4 , is of great interest as the promising battery-type electrode material for asymmetric supercapacitor (ASC). However, such material has its own disadvantages of energy waste of preparation and poor electrical conductivity. In this work, we adopted a green and environmentally friendly room-temperature sulfurization method to successfully prepare the electrode material (ACF/NCS-HL) with activated carbon fiber (ACF) as the core and honeycomb-like NiCo 2 S 4 as the shell (NCS-HL). This material has porous structure with heterogeneous redox electron pairs and shows excellent electrochemical performance. The optimized ACF/NCS-HL exhibits remarkable specific capacitance of 1682 F g −1 at 1 A g −1 in 2 M KOH aqueous electrolyte in the three-electrode system. The asymmetric supercapacitor device with ACF/NCS-HL as positive electrode and ACF as negative electrode shows the high energy density of 49.38 W h kg −1 at the power density of 800 W kg −1 and the preeminent cycle stability up to 82.88% after 5000 cycles, indicating its promising potential application in the future as high-performance supercapacitors.