Superior lithium-ion storage performances of SnO₂ powders consisting of hollow nanoplates

Hierarchical structured transition metal oxides have attracted considerable attention as anode materials for lithium-ion batteries because they possess large surface area that can provide large contact area with the electrolyte and short diffusion distance for Li ions. Here, a hierarchical structured assembly of hollow SnO₂ nanoplates is synthesized by one-step oxidation of SnS₂ powders. The SnS₂ powders comprising of dense nanoplates synthesized by the hydrothermal method transform into SnO₂ powders comprising of hollow nanoplates by nanoscale Kirkendall diffusion at the oxidation temperature of 500 °C. After the transformation of SnS₂ into SnO₂ powders, the Brunauer-Emmett-Teller surface area of the powders increases from 22.8 to 82.7 m² g⁻¹. The hierarchical structured SnO₂ powders show superior lithium-ion storage performances compared to SnS₂ powders with the same structure. The discharge capacities of SnS₂ and SnO₂ powders at a current density of 1 A g⁻¹ for the 300th cycle are 273 and 754 mA h g⁻¹, respectively. The SnO₂ powders show a high reversible capacity of 169 mA h g⁻¹ even at an extremely high current density of 30 A g⁻¹. The outstanding electrochemical properties of the SnO₂ powders can be attributed to their unique morphological structure having hollow nanoplates and optimum crystallite size, which increases the contact area between the active materials and the electrolyte and the buffered stress caused by the volume expansion during cycling.