Advances of TiO₂ as Negative Electrode Materials for Sodium-Ion Batteries

TiO₂ is a naturally abundant material with versatile polymorphs, which has been investigated in various fields, such as photocatalysis, electrochromic devices, lithium-ion batteries, amongst others. Due to the similar (but not identical) chemistry between lithium and sodium, TiO₂ is considered as an interesting potential negative electrode material for sodium ion batteries (SIBs) and is being investigated in fundamental studies for potential applications. The recent advances of TiO₂ as negative electrode materials for SIBs are reviewed herein. Different electrochemical behaviors of TiO₂ toward lithium and sodium are introduced. The (de)sodiation mechanism and physical parameters influencing the electrochemical performance are discussed. In addition, the strategies to improve the kinetic behavior, cycling stability, and coulombic efficiency of TiO₂ negative electrode material for SIBs are reviewed. Beyond the great improvement of its electrochemical performance achieved, other challenges of TiO₂ negative electrode material for SIBs remain. These challenges need to be addressed through a comprehensive understanding of its electrochemical behavior in SIBs. This review will be beneficial to the advancement of TiO₂ for SIBs and other applications.