Facile hydrothermal synthesis of porous TiO₂ nanowire electrodes with high-rate capability for Li ion batteries

Anatase TiO2 nanowires were successfully synthesized using a low-temperature hydrothermal treatment on as-prepared one-dimensional (1D) hydrogen titanate nanowires (H2Ti3O7) at 180 °C. The anatase TiO2 nanowires were porous in nature with a high specific surface area. These nanowires were characterized using transmission electron microscopy (TEM), high-resolution TEM, x-ray powder diffraction, Raman spectroscopy, and Brunauer-Emmett-Teller (BET) measurements. The topochemical phase transformation mechanism from H₂Ti₃O₇ to anatase TiO₂ is discussed. The porous anatase TiO2 nanowire electrodes demonstrated an excellent cycling performance and superior rate capabilities compared with the H2Ti₃O₇ nanowires and the anatase TiO₂ nanowires that were prepared through calcination at 700°C. The porous anatase TiO₂ nanowires exhibited a capacity of ∼ 145 mA h g-1 at 1 C after 500 cycles and 115 mA h g^-1 at 20 C. This improvement in the long-term cycle stability and outstanding rate capability was explained by various microscopic observations of the porous 1D nanostructured nature of the nanowires during the Li intercalation/deintercalation cycles.