Hierarchically hollow NiCo2S4/graphitic nanofiber film with ultrahigh-rate capability and long-term cycling durability for asymmetrical supercapacitor

NiCo 2 S 4 nanostructures have been intensively investigated as supercapacitor electrode materials ascribing to its high conductivity and capacity. However, NiCo 2 S 4 -based electrodes suffer inferior cycling durability owing to its structural degradation during the redox process. Herein, NiCo 2 S 4 nanoneedles anchored on the graphitic carbon nanofiber mat (NiCo 2 S 4 /GCN) are synthesized via a two-pot hydrothermal method. The NiCo 2 S 4 /GCN composed of highly conductive graphitic carbon nanofiber (GCN) frameworks ensures the uniform dispersion of NiCo 2 S 4 and accelerate electron/ion transport, and NiCo 2 S 4 with porous and hollow nanostructure facilitates the diffusion of electrolyte. The NiCo 2 S 4 /GCN electrode reveals a high-energy storage capability (1775.2 F g −1 at 10 A g −1 ) and an amazing rate retention (1510.2 F g −1 at 50 A g −1 ). Furthermore, the NiCo 2 S 4 /GCN//active carbon device displays a superior energy density (52.3 W h kg −1 at 358.0 W kg −1 ) and preeminent cycle life (retention 94.7% after 10,000 cycles at 5 A g −1 ), suggesting a promising candidate in supercapacitor applications.