Fe2VO4 nanoparticles on rGO as anode material for high-rate and durable lithium and sodium ion batteries

Iron vanadate (FexVOy), especially Fe2VO4, is a promising anode material for lithium and sodium ion batteries due to their high capacity and abundant raw material resources. However, its capacity decays rapidly at high rates due to volume expansion and low electrical conductivity. Herein, uniform small Fe2VO4 nanoparticles (FVO) are grown on reduced graphene oxide (rGO) by solvothermal treatment and subsequent calcination, forming a conductive-network (FVO/rGO). The flexible rGO can effectively prevent FVO particles agglomerating and buffer the volume expansion during the reaction process. The high electrical conductive rGO and small FVO particles benefit from electrons' fast transport, improving the electrical conductivity of FVO/rGO. The sheet-like structure of FVO/rGO can be fully contacted with the electrolyte to further increase electron/ion transport. The pseudocapacitive-controlled behavior is the dominating lithium/sodium storage mechanism, which facilitates a fast charge/discharge process. As a result, FVO/rGO composite displays a stable high capacity of 1013.7 mAh g(-1) at 500 mA g(-1) after 300 cycles when it is used for lithium-ion batteries. Moreover, it shows remarkable rate capability (228.9 mAh g(-1) at 20 A g(-1)) and excellent long-cycle stability (223.6 mAh g(-1) at 10 A g(-1) after 2500 cycles). It also exhibits a high discharge capacity of 137 mAh g(-1) after 1500 cycles at 1.0 A g(-1) for sodium-ion batteries. The superior electrochemical performance proves it an ideal anode material for high-rate and durable lithium and sodium-ion batteries.