Low temperature hydrogen reduction of high surface area anatase and anatase/β-TiO₂ for high-charging-rate batteries.

Abstract

There are several strategies to improve the electrochemical performance of TiO2 as negative electrode material for Li-ion batteries. Introducing oxygen vacancies through hydrogen reduction leads to an enhancement in electrical conductivity. However, this strategy does not improve the low lithium-ion mobility. Herein, we show that by decreasing the temperature of hydrogen annealing the improved lithium-ion mobility of high-surface-area TiO2 and β-TiO2 can be combined with the enhanced electrical conductivity of oxygen deficiencies. Annealing at only 275-300 °C in pure hydrogen atmosphere successfully creates oxygen vacancies in TiO2, as confirmed by UV/Vis spectroscopy, whereas the temperature is low enough to maintain a high specific surface area and prevent β-to-anatase phase transformation. The hydrogen reduction of high-surface-area anatase or anatase/β-TiO2 at these temperatures leads to improvements in the performance, achieving charge capacities of 142 or 152 mAh g(-1) at 10C, respectively.