Searching anode materials is an important task for the development of sodium-ion batteries. In this regard, bronze-phase titanium dioxide, TiO
2(B), has been considered as one of the promising materials, owing to its crystal structure with open channels and voids facilitating Na
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Searching anode materials is an important task for the development of sodium-ion batteries. In this regard, bronze-phase titanium dioxide, TiO
2(B), has been considered as one of the promising materials, owing to its crystal structure with open channels and voids facilitating Na
+ diffusion and storage. However, the electrochemical de-/sodiation mechanism of TiO
2(B) has not been clearly comprehended, and further experiments are required. Herein,
in situ and
ex situ observations by a combination of X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, gas chromatography–mass spectrometry was used to provide additional insights into the electrochemical reaction scenario of bronze-phase TiO
2 in Na-ion batteries. The findings reveal that de-/sodiation of TiO
2(B) occurs through a reversible intercalation reaction and without the involvement of the conversion reaction (no metallic titanium is formed and no oxygen is released). At the same time, upon the first Na
+ uptake process, crystalline TiO
2(B) becomes partially amorphous, but is still driven by the Ti
4+/Ti
3+ redox couple. Importantly, TiO
2(B) has pseudocapacitive electrochemical behavior during de-/sodiation based on a quantitative analysis of the cyclic voltammetry data. The results obtained in this study complement existing insights into the sodium storage mechanisms of TiO
2(B) and provide useful knowledge for further improving its anode performance for SIBs application.
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