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

Ferroferric oxide (FeO) 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 FeN@FeO/VN heterostructure via a hydrothermal and followed nitridation process, where the wrapping of conductive FeN on the surface of FeO effectively improves the electron conductivity and alleviates the volume expansion, and VN inhibits the agglomeration of FeN@FeO. Benefiting from the dual conductive confinements and promoted interfacial charge transfer, the FeN@FeO/VN heterojunction exhibits excellent rate capability and cycling stability. It possesses the highest reversible capacity of 420.8 mAh g at 1 A g after 600 cycles, which is three times that of FeO. Furthermore, a full cell based on a FeN@FeO/VN anode and a LiFePO cathode delivers considerable electrochemical performance. This work demonstrates that FeN@FeO/VN is a potential anode material and provides a model in constructing other high-performance electrode materials.