Oxygen-Doped MoS₂ with Expanded Interlayer Spacing for Rapid and Stable Polysulfide Conversion.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Lithium-sulfur batteries are promising for high energy density storage.
• Key challenges include the polysulfide shuttle effect and poor sulfur utilization, limiting cycle life.
• Molybdenum disulfide (MoS₂) is explored as a catalyst but requires optimization.

Purpose of the Study:

• To develop an oxygen-doped engineering approach for MoS₂ with extended interlayer spacing (E-MoS₂).
• To enhance lithium polysulfide conversion efficiency in lithium-sulfur batteries.
• To improve the cyclic stability and sulfur utilization of MoS₂-based cathodes.

Main Methods:

• Oxygen doping was used to create pillar-free interlayer extension of MoS₂.
• Characterization of E-MoS₂ for expanded interlayer spacing (0.63 to 0.95 nm), conductivity, and electronic structure.
• Electrochemical testing of E-MoS₂ in lithium-sulfur battery configurations.

Main Results:

• E-MoS₂ exhibited significantly expanded interlayer spacing and improved conductivity.
• Optimized Mo d band center in E-MoS₂ enhanced polysulfide conversion kinetics.
• Cathodes with E-MoS₂ achieved a capacity of 638 mAh g^-1 after 600 cycles at 2 C with low decay (0.046%/cycle).
• High areal capacity of 12.0 mAh cm^-2 was demonstrated under practical conditions.

Conclusions:

• Interlayer engineering of MoS₂ is a viable strategy to overcome polysulfide shuttle and sluggish kinetics.
• Oxygen-doped E-MoS₂ significantly improves sulfur utilization and cyclic stability in lithium-sulfur batteries.
• This approach offers a pathway for developing high-performance conversion-type batteries.