Heterointerface Engineering for Stepwise Catalysis of Polysulfides in High Sulfur Loading Lithium-Sulfur Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Lithium-sulfur (Li-S) batteries face challenges from polysulfide shuttle effects and slow reaction kinetics, limiting their practical application.
• Single-component catalysts often fail to provide sustained activity for the complex redox reactions in Li-S cells.

Purpose of the Study:

• To design and synthesize an advanced sulfur host material for Li-S batteries that addresses the shuttle effect and sluggish kinetics.
• To investigate the synergistic effects of morphology and interface engineering in a novel catalyst for improved Li-S battery performance.

Main Methods:

• Fabrication of a nanoflower-structured CoS/Co9S8 heterojunction using a MOF template.
• Characterization of the material's structure, composition, and electrochemical properties.
• Assembly and testing of Li-S cells with the developed sulfur host under high sulfur loading.

Main Results:

• The CoS/Co9S8 heterojunction exhibits a built-in electric field at the p-n interface, promoting charge transfer and polysulfide migration.
• The hierarchical porous structure and dual catalytic sites facilitate stepwise conversion of lithium polysulfides.
• Achieved high sulfur loading (84 wt.%), high discharge capacity (1295.9 mAh g⁻¹), excellent cycling stability (0.069% decay per cycle over 300 cycles), and high volumetric capacity (1082.07 mAh cm⁻³).

Conclusions:

• The CoS/Co9S8 heterojunction serves as an effective sulfur host by synergistically combining morphology and interface engineering.
• This advanced material significantly mitigates the shuttle effect and enhances the kinetics of Li-S batteries.
• The developed strategy paves the way for high-energy-density and long-term stable Li-S batteries.