Manipulating Electrocatalytic Li₂ S Redox via Selective Dual-Defect Engineering for Li-S Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical energy density but suffer from polysulfide shuttle and slow redox kinetics.
• Existing redox mediators struggle with effective bidirectional sulfur electrocatalysis.

Purpose of the Study:

• To develop a novel electrocatalyst for Li-S batteries by engineering defects in MoSe2.
• To investigate the mechanistic role of dual defects (N-doping and Se-vacancies) in enhancing sulfur electrochemistry.

Main Methods:

• Selective dual-defect engineering of MoSe2 (N-doping and Se-vacancies).
• Theoretical prediction and electrokinetic analysis to understand defect effects.
• Fabrication and testing of Li-S battery cells with the engineered electrocatalyst.

Main Results:

• The engineered MoSe2 catalyst demonstrated selective bidirectional sulfur electrocatalysis.
• Li-S batteries achieved excellent cyclability (0.04% capacity decay per cycle over 1000 cycles at 2.0 C).
• High areal capacity (7.3 mAh cm-2) and flexible pouch cell construction demonstrated practical viability.

Conclusions:

• Dual-defect engineering of MoSe2 provides a viable strategy for advanced Li-S battery electrocatalysis.
• This approach effectively mitigates polysulfide shuttling and improves redox kinetics.
• The findings pave the way for practical, high-performance Li-S battery systems.