Sn-MOF derived bimodal-distributed SnO2 nanosphere as a high performance anode of sodium ion batteries with high gravimetric and volumetric capacities

This paper reported a high tap density SnO2 nanosphere with bimodal sizes distribution, which derived from Sn-based metal-organic frameworks (Sn-MOF) precursors. When used as anodes for Na-ion batteries, the SnO2 nanosphere was demonstrated with a high reversible sodium storage capacity of 417 mAh g−1 at a current density of 50 mA g−1 after 100 cycles. Even at a high current density of 1200 mA g−1, a reversible capacity of 105 mAh g−1 can be obtained. Additionally, regarding to the packed volumetric capacity, the SnO2 nanosphere electrode demonstrated a high value of around 970 mAh cm−3, can be considered as a high volumetric capacity anode material. The excellent electrochemical performance could be ascribed to aspects of structural stability, high packing density and high Na+ diffusion rates of the SnO2 nanosphere electrode. This work provides a new pathway to prepared nanostructured SnO2 materials, and demonstrated a high performance anode material for Na-ion battery with great specific capacity and cycling performance.