Sulfur-Doped Anatase Titanium Dioxide Induced by Polysulfide Chemistry for Enhanced Lithium-Ion Storage Performance

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Substitutional anion doping of titanium dioxide (TiO2) with sulfur introduces oxygen vacancies, improving conductivity and ion storage.
• Enhanced electronic conductivity and ion diffusion kinetics are crucial for high-performance lithium-ion battery anodes.

Purpose of the Study:

• To synthesize sulfur-doped anatase titanium dioxide (S-TiO2(A)) using polysulfide anions as a sulfur source.
• To evaluate the electrochemical performance of S-TiO2(A) as an anode material for lithium-ion storage.
• To compare the performance of S-TiO2(A) against undoped TiO2 (amorphous, anatase, and rutile phases).

Main Methods:

• Simultaneous hydrolysis of titanium tetrachloride (TiCl4) and polysulfide anion disproportionation at 80 °C to form S/TiO2(a).
• Annealing of S/TiO2(a) to obtain S-TiO2(A).
• Preparation of control samples: TiO2(a), TiO2(A), and TiO2(R).
• Electrochemical testing including capacity, initial Coulombic efficiency (ICE), rate capability, and cycling performance.
• Ex situ electrochemical impedance spectrometry (EIS) and X-ray diffraction (XRD) for mechanism analysis.

Main Results:

• S-TiO2(A) exhibited superior electrochemical performance compared to undoped amorphous, anatase, and rutile TiO2.
• Key improvements were observed in capacity, initial Coulombic efficiency (ICE), rate capability, and cycling stability.
• Enhanced electronic conductivity and lithium-ion diffusion kinetics were identified as the reasons for improved performance.

Conclusions:

• Polysulfide anions are effective sulfur sources for preparing S-TiO2(A) for high-performance lithium-ion battery anodes.
• Sulfur doping significantly enhances the electrochemical properties of anatase TiO2 for energy storage applications.
• The study highlights a viable strategy for developing advanced anode materials for lithium-ion batteries.