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

Abstract

NiCo2S4 nanostructures have been intensively investigated as supercapacitor electrode materials ascribing to its high conductivity and capacity. However, NiCo2S4-based electrodes suffer inferior cycling durability owing to its structural degradation during the redox process. Herein, NiCo2S4 nanoneedles anchored on the graphitic carbon nanofiber mat (NiCo2S4/GCN) are synthesized via a two-pot hydrothermal method. The NiCo2S4/GCN composed of highly conductive graphitic carbon nanofiber (GCN) frameworks ensures the uniform dispersion of NiCo2S4 and accelerate electron/ion transport, and NiCo2S4 with porous and hollow nanostructure facilitates the diffusion of electrolyte. The NiCo2S4/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 NiCo2S4/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.