Mesoporous TiO₂ coating on carbon-sulfur cathode for high capacity Li-sulfur battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sulfur cathodes in lithium-sulfur batteries suffer from polysulfide dissolution, leading to capacity fading.
• Activated carbon powder (ACP) derived from biomass offers a sustainable sulfur host, but requires protection against polysulfide shuttling.

Purpose of the Study:

• To develop and evaluate a mesoporous titania (TiO2) coating as a protective layer for carbon-sulfur composite cathodes.
• To investigate the impact of the titania coating on the electrochemical performance and stability of sulfur cathodes.

Main Methods:

• Fabrication of carbon-sulfur cathodes using biomass-derived ACP and sulfur, followed by coating with a mesoporous titania layer.
• Electrochemical characterization including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).
• Surface analysis using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) to confirm polysulfide adsorption.

Main Results:

• The mesoporous titania coated cathodes demonstrated excellent capacity retention (980 mA h g-1) after 100 cycles at C/3.
• EIS data revealed stable charge transfer resistance for the titania-coated electrode, unlike the uncoated electrode, indicating mitigation of polysulfide shuttling.
• CV stability and Raman/XPS studies confirmed effective adsorption of soluble polysulfides by the mesoporous titania layer.

Conclusions:

• Mesoporous titania coatings are highly effective in preventing polysulfide dissolution in carbon-sulfur cathodes.
• The titania coating significantly enhances the cycling stability and electrochemical performance of sulfur-based batteries.
• This approach offers a promising strategy for developing high-performance and durable lithium-sulfur batteries.