Manipulating Electrolyte Interface Chemistry Enables High-Performance TiO2 Anode for Sodium-Ion Batteries

Titanium dioxide (TiO2) has emerged as a candidate anode material for sodium-ion batteries (SIBs). However, their applications still face challenges of poor rate performance and low initial coulomb efficiency (ICE), which are induced by the unstable solid-electrolyte interface (SEI) and sluggish Na+ diffusion kinetics in conventional ester-based electrolytes. Herein, inspired by the electrode/electrolyte interfacial chemistry, tetrahydrofuran (THF) is exploited to construct an advanced electrolyte and reveal the relationship between the improved electrochemical performance and the derived SEI film on TiO2 anode. The robust and homogeneously distributed F-rich SEI film formed in THF electrolyte favors fast interfacial charge transfer dynamics and excellent interfacial stability. As a result, the THF electrolyte endows the TiO2 anode with greatly improved ICE (64.5%), exceptional rate capabilities (186 mAh g-1 at 5.0 A g-1), and remarkable cycling stability. This study elucidates the control of interfacial chemistry by rational electrolyte design and offers insights into the development of high-performance and long-lifetime TiO2 anode.