Cu–V bimetallic selenide with synergistic effect for high-rate and long-life sodium storage

Sodium-ion batteries (SIBs) are considered as potential substitute in large-scale energy storage systems due to the abundant natural resources and low price of sodium, and environmental friendliness. However, commercial graphite anode in lithium-ion batteries cannot be directly applied to SIBs. Bimetallic selenides stand out among the many anode materials owing to their rich redox chemistry and superior conductivities. Here, a bimetallic selenide Cu 3 VSe 4 is successfully prepared via one-pot reaction in oil phase, and its energy storage performance for SIBs is investigated. It delivers an impressive capacity, excellent rate performance (298 mAh g −1 at 10 A g −1 ), and outstanding long-term cycling life (305 mAh g −1 over 1000 cycles at 2.0 A g −1 ). In addition, the Na + storage mechanism (including intercalation and conversion reactions) is revealed. This work provides a new way for the application of the Cu 3 VSe 4 in SIBs. Graphical abstract A bimetallic selenide Cu 3 VSe 4 is successfully prepared via one-pot reaction in oil phase. When it is evaluated as the anode for sodium-ion batteries, the Cu 3 VSe 4 displays an impressive capacity, excellent rate performance, and outstanding long-term cycling life. In addition, the Na + storage mechanism (including intercalation and conversion reactions) is revealed.