Efficient Heterojunction Electrocatalysts for Polysulfide Conversion in Li-S Batteries via Dual-Geometric...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Heterostructure electrocatalysts are crucial for catalyzing lithium polysulfide conversion in lithium-sulfur batteries.
• Understanding the structure-activity relationship in heterojunctions is vital for designing efficient electrocatalysts.

Purpose of the Study:

• To investigate the geometric-configuration-dependent catalytic activity for lithium polysulfide conversion using molybdenum carbides (Mo_xC) as model electrocatalysts.
• To elucidate the role of interfacial geometric coordination in heterojunctions for lithium polysulfide retention and catalysis.

Main Methods:

• Systematic investigation of molybdenum carbide (Mo_xC) crystal structures and their catalytic activity for lithium polysulfide conversion.
• Experimental analysis of interfacial configuration, lithium polysulfide affinity, and charge transfer kinetics.
• Fabrication and testing of lithium-sulfur batteries using MoC/Mo₂C heterojunctions.

Main Results:

• Cubic MoC (Mo_oct) shows strong lithium polysulfide affinity leading to passivation.
• Hexagonal Mo₂C (Mo_tri) enhances interfacial charge transfer.
• MoC/Mo₂C heterojunctions exhibit moderate lithium polysulfide adsorption and favorable charge transfer kinetics.
• MoC/Mo₂C based lithium-sulfur batteries demonstrate superior reversible specific capacities and cycling durability.

Conclusions:

• Interfacial geometric coordination critically influences lithium polysulfide retention and catalysis in heterojunctions.
• Dual-geometric coordination in MoC/Mo₂C heterostructures provides a promising strategy for enhancing lithium-sulfur battery performance.
• This work offers a guiding approach for the rational design of high-activity heterojunction electrocatalysts.