Facile synthesis of NiS anchored carbon nanofibers for high-performance supercapacitors

Highlights: • NiS carbon nanofibers were obtained through electrospinning combined with calcination and in situ sulfurization. • CNFs-NiS has accessible specific surface, unique porous structure and high specific capacity. • Asymmetric supercapacitor has an enhanced volumetric energy density and high cycling stability. Transition metal sulfide compounds with carbon materials are promising for high-performance supercapacitors. Carbon nanofibers (CNFs) wrapped with NiS nanoparticles were herein obtained through electrospinning and calcination. NiS nanoparticles in composite nanofibers are covered by a layer of graphitic carbon, which not only increase the conductivity but also provide active regions for nanoparticle growth to prevent aggregation. The CNFs-NiS electrode has high specific capacity of 177.1 mAh g⁻¹ at 1 A g⁻¹ (0.41 mAh cm⁻² at a current density of 2.3 mA cm⁻²) and long-term cycling stability, with 88.7% capacitance retention after 5000 cycles. The excellent electrochemical activity may be attributed to the accessible specific surface, unique porous structure of CNFs and high specific capacitance of NiS. In addition, the asymmetric supercapacitor has an enhanced volumetric energy density of 13.32 mWh cm⁻³ at a volumetric power density of 180 mW cm⁻³ and high cycling stability, with 89.5% capacitance retention after 5000 cycles. It also successfully lights up a light-emitting diode. The CNFs-NiS composite has significant potential applications in supercapacitor.