title: A new sodiation-desodiation mechanism of the titania-based negative electrode for sodium-ion batteries.
abstract: TiO2is widely investigated as a negative electrode for lithium-ion batteries. In sodium-ion batteries, however, the sodiation-desodiation mechanism of TiO2is still unclear. Here, we report a new sodiation-desodiation mechanism for an anatase TiO2/C electrode in an ionic liquid electrolyte at 90 °C, where it shows a high reversible capacity of 278 mA h g-1. During the first charge process, TiO2reacts with Na ions to form a Na2TiIITiIVO4solid solution. During the first discharge process, the solid solution converts into a mixture of TiO2, Na2TiO3, and TiO, with the former two being X-ray amorphous. In the subsequent cycle, the mixture acts as the active material, reversibly reacting with Na ions to re-form the Na2TiIITiIVO4solid solution. This mechanism, which has not been reported for Na or Li ion insertion-extraction in anatase TiO2, can help understand this promising electrode material and develop safe sodium-ion batteries with high energy density.
authors: Graduate School of Energy Science, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. hagiwara@energy.kyoto-u.ac.jp.
authors: Changsheng
authors: C
authors: Ding
authors: Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan. nohira.toshiyuki.8r@kyoto-u.ac.jp.
authors: Toshiyuki
authors: T
authors: Nohira
authors: Graduate School of Energy Science, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. hagiwara@energy.kyoto-u.ac.jp.
authors: Rika
authors: R
authors: Hagiwara