Interfacial Synergy in Mo₂C/MoC Heterostructure Promoting Sequential Polysulfide Conversion in High-Performance...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Polysulfide shuttle effects impede lithium-sulfur (Li-S) battery performance.
• Heterostructure catalysts offer potential solutions by providing multiple active sites.
• Understanding surface and interface functionalities in heterostructures is crucial.

Purpose of the Study:

• To design and investigate a Mo2C/MoC heterostructure catalyst for enhanced Li-S battery performance.
• To elucidate the roles of the material surface and interface in polysulfide conversion.
• To demonstrate the synergistic effects of different active regions within the heterostructure.

Main Methods:

• In situ conversion of a MoZn-metal organic framework to create the Mo2C/MoC catalyst.
• Experimental characterization and computational simulations to study catalyst properties.
• Assembly and testing of Li-S batteries using the developed Mo2C/MoC-sulfur cathode.

Main Results:

• The Mo2C/MoC catalyst exhibits a tri-active-region structure (Mo2C surface-interface-MoC surface).
• The interface effectively captures and converts long-chain polysulfides.
• Mo2C and MoC surfaces accelerate short-chain polysulfide conversion and Li2S dissociation.
• Li-S batteries with the Mo2C/MoC-S cathode show a high initial capacity (1603.6 mAh g⁻¹ at 1 C) and excellent cycling stability (80.4% capacity retention after 1000 cycles at 3 C).

Conclusions:

• The developed Mo2C/MoC heterostructure catalyst significantly mitigates polysulfide shuttle effects.
• A novel synergy between the material surface and interface enhances catalytic activity.
• This work provides a pathway for designing high-performance Li-S batteries through rational heterostructure design.