MOF-Derived FeNb ₂ O ₆ /Carbon Nanofiber Hybrids with Enhanced Kinetics for High-Rate Lithium Storage

Niobium-based oxides, such as iron niobate (FeNb2O6), are promising for high-rate lithium storage but suffer from low electrical/ionic conductivity, leading to rapid energy/power density decay. Herein, a synergistic strategy of nanoporous structure design and carbon nanofiber composite is employed. Fe-MOFs is used as precursors to prepare FeNb2O6/carbon nanofiber (FeNb2O6/CNF) composite via solvothermal and electrospinning methods. The mass ratio of MOF-235 to NbCl5 is optimized to obtain porous FeNb2O6 nanoparticles. Compared with FeNb2O6/C powder electrode, FeNb2O6/CNF exhibits a higher ionic diffusion coefficient. In addition, the FeNb2O6/CNF electrode achieves a higher specific capacity of 337 mA h g–1 at 1 A g–1, with 81% capacity retention after 500 cycles. At 5 A g–1, it maintains a specific capacity of about 130 mA h g–1, revealing that the carbon nanofiber structure significantly enhances electrochemical performance. Moreover, the capacitive control behavior of lithium-ion storage in FeNb2O6/CNF has been confirmed, demonstrating excellent kinetic performance.