Mesoporous TiO2-Sn/C Core-Shell Nanowire Arrays as High-Performance 3D Anodes for Li-Ion Batteries

Three‐dimensional mesoporous TiO2‐Sn/C core‐shell nanowire arrays are prepared on Ti foil as anodes for lithium‐ion batteries. Sn formed by a reduction of SnO2 is encapsulated into TiO2 nanowires and the carbon layer is coated onto it. For additive‐free, self‐supported anodes in Li‐ion batteries, this unique core‐shell composite structure can effectively buffer the volume change, suppress cracking, and improve the conductivity of the electrode during the discharge‐charge process, thus resulting in superior rate capability and excellent long‐term cycling stability. Specifically, the TiO2‐Sn/C nanowire arrays display rechargeable discharge capacities of 769, 663, 365, 193, and 90 mA h g−1 at 0.1C, 0.5C, 2C 10C, and 30C, respectively (1C = 335 mA g−1). Furthermore, the TiO2‐Sn/C nanowire arrays exhibit a capacity retention rate of 84.8% with a discharge capacity of over 160 mA h g−1, even after 100 cycles at a high current rate of 10C. Self‐supported TiO2‐Sn/C core‐shell nanowire array 3D anodes exhibiting superior electrochemical performance are developed using a facile hydrothermal process, followed by a heat treatment process. With this unique nanowire array structure, the aligned TiO2 nano­wires with a self‐supported array structure leads to high physical stability, resulting in long cycling stability. The carbon shell suppresses cracking of Sn and improves the conductivity of the electrode, thus contributing to high‐rate cyclability.