Synthesis of Flower-Like Nb₂Se₉ as High-Performance Anode Materials for Lithium-Ion and Sodium-Ion Batteries

In this work, a flower-like Nb₂Se₉ material was obtained by a simple oil-phase-assisted synthesis route and used as an anode in lithium-ion and sodium-ion batteries first. It exhibited a high charge capacity (672.35 mAh g^–1 at 100 mA g^–1), good cycling stability (596.63 mAh g^–1 after 250 cycles at 100 mA g^–1), and outstanding rate performance (285 mAh g^–1 at 5 A g^–1) in lithium-ion batteries. Meanwhile, the ex situ X-ray diffraction result reveals that the lithium storage mechanism of Nb₂Se₉ is the conversion reaction. As an anode for sodium-ion batteries, Nb₂Se₉ delivered an initial reversible capacity of 342.60 mAh g^–1 at the current density of 100 mA g^–1 and was stabilized at 230.36 mAh g^–1 over 500 cycles after the initial 50 cycles. Excellent electrochemical performance may be attributed to the special micro–nano hierarchical structure of the flower-like Nb₂Se₉ material, which greatly promotes ion diffusion and provides abundant active sites. These results indicate that flower-like Nb₂Se₉ is a promising anode material for both lithium-ion and sodium-ion batteries.