α-Fe ₂O ₃-mediated growth and carbon nanocoating of ultrafine SnO ₂ nanorods as anode materials for Li-ion batteries

Bulk synthesis of SnO ₂ nanorods under acidic conditions has rarely been reported. In this work, ultrafine SnO ₂ nanorods with a diameter of less than 10 nm and a length of 50-100 nm have been synthesized by an interesting α-Fe ₂O ₃-mediated hydrothermal method under strongly acidic conditions. It has been found that the formation of SnO ₂ nanorods is induced by the α-Fe ₂O ₃ substrate due to good compatibility of the two crystal lattices. The α-Fe ₂O ₃ substrate is dissolved under acidic conditions, leading to the formation of pure SnO ₂ nanorods. After surface coating with a layer of amorphous carbon, the resulting carbon-coated SnO ₂ nanorods are evaluated as high-capacity anode materials for lithium-ion batteries. Remarkably, they exhibit greatly improved cycling stability with a high capacity of around 800 mA h g ^-1 at 0.2 C and satisfactory performance even at higher current rates of 0.5-1 C within 50 cycles. The excellent electrochemical performance is attributed to the unique one-dimensional nanostructure and the carbon nanocoating. © 2012 The Royal Society of Chemistry.