Highly crystalline antimony oxide octahedron: an efficient anode for sodium-ion batteries

Sodium-ion batteries are being explored as an alternative to the Li-ion batteries, due to the abundance of Na and similar electrochemistry with that of Li. In this study, we report the electrochemical activity of octahedron-like antimony trioxide nanostructures for Na-ion batteries, prepared with the simple hydrothermal oxidation of antimony precursor in alkaline condition. The microstructure reveals the formation of octahedron-like microcrystals with cubic antimony trioxide phase. In Na-ion cells, the antimony trioxide electrode exhibits a reversible specific capacity of 623 mAh g−1 on the first charge and long cycle stability of 200 cycles losing only 9% capacity. The exceptional electrochemical performance achieved by antimony trioxide is owing to the conversion and alloying reactions mechanism, which accelerates the kinetics of the reactions by stabilizing the structure of anode material.