A Scalable Strategy To Develop Advanced Anode for Sodium-Ion Batteries: Commercial Fe3O4-Derived Fe3O4@FeS with Superior Full-Cell Performance

A novel core–shell Fe3O4@FeS composed of Fe3O4 core and FeS shell with the morphology of regular octahedra has been prepared via a facile and scalable strategy via employing commercial Fe3O4 as the precursor. When used as anode material for sodium-ion batteries (SIBs), the prepared Fe3O4@FeS combines the merits of FeS and Fe3O4 with high Na-storage capacity and superior cycling stability, respectively. The optimized Fe3O4@FeS electrode shows ultralong cycle life and outstanding rate capability. For instance, it remains a capacity retention of 90.8% with a reversible capacity of 169 mAh g–1 after 750 cycles at 0.2 A g–1 and 151 mAh g–1 at a high current density of 2 A g–1, which is about 7.5 times in comparison to the Na-storage capacity of commercial Fe3O4. More importantly, the prepared Fe3O4@FeS also exhibits excellent full-cell performance. The assembled Fe3O4@FeS//Na3V2(PO4)2O2F sodium-ion full battery gives a reversible capacity of 157 mAh g–1 after 50 cycles at 0.5 A g–1 with a capacity retention of...