S-La₂Mo₂O₉ solid solution: a sulfur cathode with a non-shaped matrix enables a better lithium-sulfur battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Conventional lithium-sulfur batteries utilize prefabricated matrices to mitigate the shuttle effect.
• Existing methods often face limitations in achieving optimal performance and cycle stability.

Purpose of the Study:

• To introduce a novel, non-shaped matrix for sulfur cathodes in lithium-sulfur batteries.
• To investigate the potential of La₂Mo₂O₉ as a component in sulfur cathodes.
• To enhance the discharge capacity and cycle stability of lithium-sulfur batteries.

Main Methods:

• Incorporation of the fast oxide-ion conductor La₂Mo₂O₉ into sulfur cathodes.
• Formation of a highly dispersed solid solution (LMO-in-S) with homogeneous mixing at the molecular level.
• Electrochemical testing to evaluate gravimetric and volumetric capacity, cycle stability, and sulfur content.

Main Results:

• The LMO-in-S cathode demonstrated a high gravimetric capacity of 1374.1 mAh g^-1 and volumetric capacity of 2294.8 mAh cm^-3 at 0.1C.
• Exceptional cycle stability was observed with a low fade rate of 0.07% per cycle over 400 cycles at 1C.
• The material enabled an ultra-high sulfur content (92.6 wt%) while maintaining a high capacity of 1076.5 mAh g^-1 at 0.1C.

Conclusions:

• The non-shaped La₂Mo₂O₉ matrix significantly improves lithium-sulfur battery performance by providing high surface contact and catalytic activity.
• This approach breaks conventional structural concepts for sulfur cathodes, offering a novel strategy for developing high-performance lithium-sulfur batteries.