High power TiO2 and high capacity Sn-doped TiO2 nanomaterial anodes for lithium-ion batteries

A range of phase-pure anatase TiO2 (∼5 nm) and Sn-doped TiO2 nanoparticles with the formula Ti1-xSnxO2 (where x = 0, 0.06, 0.11 and 0.15) were synthesized using a continuous hydrothermal flow synthesis (CHFS) reactor. Charge/discharge cycling tests were carried out in two different potential ranges of 3 to 1 V and also a wider range of 3 to 0.05 V vs Li/Li+. In the narrower potential range, the undoped TiO2 nanoparticles display superior electrochemical performance to all the Sn-doped titania crystallites. In the wider potential range, the Sn-doped samples perform better than undoped TiO2. The sample with composition Ti0.85Sn0.15O2, shows a capacity of ca. 350 mAh g−1 at an applied constant current of 100 mA g−1 and a capacity of 192.3 mAh g−1 at a current rate of 1500 mA g−1. After 500 charge/discharge cycles (at a high constant current rate of 382 mA g−1), the same nanomaterial anode retains a relatively high specific capacity of 240 mAh g−1. The performance of these nanomaterials is notable, particularly as they are processed into electrodes, directly from the CHFS process (after drying) without any post-synthesis heat-treatment, and they are made without any conductive surface coating.