FeOF nanoparticles wrapped by graphitic carbon layers prepared from Fe-MIL-88B as a cathode material for sodium-ion batteries

Abstract

Sodium-ion batteries (SIBs) are considered a promising alternative for lithium-ion batteries because of the abundance and economic benefits of sodium. Iron oxyfluoride (FeOF) is attractive as a cathode material for SIBs because of its high theoretical capacity (∼855 mA h g−1), low cost, and environmental friendliness. However, FeOF often suffers from poor rate capability and cycling stability because of its low electronic conductivity and ion diffusion coefficient. In this work, we synthesize FeOF nanoparticles wrapped in graphitic carbon layers in situ prepared from an Fe-containing metal organic framework, Fe-MIL-88B. The FeOF electrode exhibits excellent cycling performance with reversible capacities above 338 mA h g−1 at the 100th cycle and a current density of 100 mA g−1. In addition, the rate capability is significantly improved in comparison with that of FeOF alone.