Tunable Control of Indium Cluster in Carbon Nanofibers for High-Performance Zinc-Ion Hybrid Capacitors

Porous carbon has emerged as a potential material for the cathode of zinc-ion hybrid capacitors (ZIHCs), owing to its abundant active sites and efficient ion diffusion properties. In this work, a porous carbon nanofiber (CNF) is fabricated using a facile electrospinning process with polyvinylpyrrolidone (PVP), polyacrylonitrile (PAN), and indium chloride (InCl₃). By adjusting the suitable carbonization temperature to 800 °C, suitable gradient pore sizes ranging from mesopores to micropores feature a good electrolyte penetration, while the nitrogen (N) doping and indium clusters provide rich active sites to improve the charge storage mechanism. Benefiting the features above, it achieves a reversible specific capacity of 80 mAh g⁻¹ at 0.3 A g⁻¹ and retains ≈100% capacity retention after 15 000 cycles at 50 A g⁻¹ current. This work provides new insights into electrode design for developing high-rate ZIHCs.