Carbon-Coated Tin-Titanate derived SnO₂/TiO₂ nanowires as High-Performance anode for Lithium-Ion batteries

Tin dioxide (SnO₂) is a promising alternative material to graphite anode, but the large volume change induced electrode pulverization issue has limited its application in lithium-ion batteries (LIBs). In contrast, titanium dioxide (TiO₂) anode shows high structure stability upon lithium insertion/extraction, but with low specific capacity. To overcome their inherent disadvantages, combination of SnO₂ with TiO₂ and highly conductive carbon material is an effective way. Herein, we report a facile fabrication method of carbon-coated SnO₂/TiO₂ nanowires (SnO₂/TiO₂@C) using tin titanate nanowires as precursor, which are prepared by reacting SnCl₂·2H₂O with layered sodium titanate (Na₂Ti₃O₇) nanowires in the aqueous solution though the ion exchange between Sn²⁺ and Na⁺. After annealing under argon atmosphere, the hydrothermally carbon-coated tin-titanate nanowires decompose, forming a unique hybrid structure, where ultrafine SnO₂ nanoparticles are uniformly embedded within the TiO₂ substrate with carbon coating. Consequently, the SnO₂/TiO₂@C nanowires demonstrate excellent lithium storage capacity with high pseudocapacitance contribution, excellent reversible capacity, and long-term cycling stability (673.7/510.5 mAh/g at 0.5/1.0 A/g after 250/800 cycles), owing to the unique hybrid structure, as the well-dispersion of ultra-small SnO₂ within TiO₂ nanowire substrate with simultaneous carbon coating efficiently suppresses the volume changes of SnO₂, provides abundant reactive sites for lithium storage, and enhances the electrical conductivity with shortened ion transport distance.