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

Abstract

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 92.3% and the Coulombic efficiency of around 100%, demonstrating its applicability for sodium-ion full batteries as a promising anode. Furthermore, it is also disclosed that such superior electrochemical properties can be attributed to the pseudocapacitive behavior of FeS shell as demonstrated by the kinetics studies as well as the core-shell structure. In view of the large-scale availability of commercial precursor and ease of preparation, this study provide a scalable strategy to develop advanced anode materials for SIBs.