Synergistic NiCo₂S₄ and carbon nanofiber hybrids delivering high capacitance and cycling stability

In this study, a high-performance hybrid electrode material was synthesized comprising nickel cobalt sulfide (NiCo₂S₄) nanoparticles supported on mesoporous carbon nanofibers (CNFs) for supercapacitors. The CNFs were prepared by electrospinning a polyacrylonitrile and polyvinylpyrrolidone blend solution, followed by carbonization, and subsequent hydrothermal deposition of NiCo₂S₄. The resulting NiCo₂S₄@CNFs hybrid exhibited a hierarchical structure with nanoscale dispersion of the active material and high electrical conductivity. Electrochemical measurements revealed a high specific capacitance of 2327 F g⁻¹ at 1 A g⁻¹, along with specific energy and specific power of 51.71 Wh kg⁻¹ and 200 W kg⁻¹, respectively. Despite a low BET surface area (~5 m² g⁻¹), the electrode exhibited a high electrochemically active surface area. Notably, the electrode retained 84% of its capacitance after 3000 charge-discharge cycles. Differential current separation analysis confirmed that over 83% of the total charge storage is derived from the surface-controlled processes, demonstrating the kinetic dominance of the NiCo₂S₄ component. This performance highlights the efficacy of the synergistic composite architecture for optimizing charge transfer and utilization of active sites, positioning transition metal sulfide/carbon hybrids as highly viable electrode candidates for advanced energy storage.