NiCo₂S₄nanosheets decorated on nitrogen-doped hollow carbon nanospheres as advanced electrodes for high-performance...

Taking advantage of both Faradaic and carbonaceous materials is an efficient way to synthesize composite electrodes with enhanced performance for supercapacitors. In this study, NiCo₂S₄nanoflakes were grown on the surface of nitrogen-doped hollow carbon nanospheres (NHCSs), forming a NiCo₂S₄/NHCS composite with a core-shell structure. This three-dimensionally confined growth of NiCo₂S₄can effectively inhibit its aggregation and facilitate mass transport and charge transfer. Accordingly, the NiCo₂S₄/NHCS composite exhibited high cycling stability with only 9.2% capacitance fading after 10 000 cycles, outstanding specific capacitance of 902 F g^-1at 1 A g^-1, and it retained 90.6% of the capacitance at 20 A g^-1. Moreover, an asymmetric supercapacitor composed of NiCo₂S₄/NHCS and activated carbon electrodes delivered remarkable energy density (31.25 Wh kg^-1at 750 W kg^-1), excellent power density (15003 W kg^-1at 21.88 Wh kg^-1), and satisfactory cycling stability (13.4% capacitance fading after 5000 cycles). The outstanding overall performance is attributed to the synergistic effect of the NiCo₂S₄shell and NHSC core, which endows the composite with a stable structure, high electrical conductivity, abundant active reaction sites, and short ion-transport pathways. The synthesized NiCo₂S₄/NHCS composite is a competitive candidate for the electrodes of high-performance supercapacitors.