Dual interfaces and confinements on Fe2N@Fe3O4/VN heterojunction toward high-efficient lithium storage.

Ferroferric oxide (Fe3O4) as an anode material of lithium-ion battery has been widely investigated due to its high theoretical capacity, environmental friendliness, natural abundance, and low cost. However, it suffers from severe aggregation and volume expansion during energy storage. Herein, we rationally construct an advanced Fe2N@Fe3O4/VN heterostructure via a hydrothermal and followed nitridation process, where the wrapping of conductive Fe2N on the surface of Fe3O4 effectively improves the electron conductivity and alleviates the volume expansion, and VN inhibits the agglomeration of Fe2N@Fe3O4. Benefiting from the dual conductive confinements and promoted interfacial charge transfer, the Fe2N@Fe3O4/VN heterojunction exhibits excellent rate capability and cycling stability. It possesses the highest reversible capacity of 420.8 mAh g-1 at 1 A g-1 after 600 cycles, which is three times that of Fe3O4. Furthermore, a full cell based on a Fe2N@Fe3O4/VN anode and a LiFePO4 cathode delivers considerable electrochemical performance. This work demonstrates that Fe2N@Fe3O4/VN is a potential anode material and provides a model in constructing other high-performance electrode materials.