Flash Joule Heating: A Promising Method for Preparing Heterostructure Catalysts to Inhibit Polysulfide Shuttling in...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical energy density but are hampered by the polysulfide shuttle effect.
• This effect, caused by soluble lithium polysulfides migrating between electrodes, degrades battery performance and lifespan.
• Developing efficient catalysts is crucial to mitigate polysulfide shuttling and improve Li-S battery practicality.

Purpose of the Study:

• To synthesize and evaluate a novel W-W2C/G heterostructure as a catalytic interlayer for Li-S batteries.
• To investigate the catalytic mechanism underlying polysulfide conversion and shuttle effect suppression.
• To assess the electrochemical performance of Li-S batteries incorporating the W-W2C/G interlayer.

Main Methods:

• One-step flash-Joule-heating synthesis of W-W2C/G heterostructure on a graphene substrate.
• Theoretical calculations (e.g., work function analysis) to understand the interfacial electric field effect.
• In situ Raman spectroscopy to analyze polysulfide behavior and catalytic activity.
• Electrochemical testing of Li-S cells, including rate capability and long-term cycling.

Main Results:

• The W-W2C/G heterostructure generates an internal electric field, promoting electron and ion transport and enhancing the sulfur reduction reaction (SRR).
• In situ Raman analyses confirmed reduced activation energy and suppressed polysulfide shuttling.
• Li-S batteries with the W-W2C/G interlayer demonstrated excellent rate performance (665 mAh g⁻¹ at 5.0 C) and remarkable cycling stability (0.06% decay over 1000 cycles at 3.0 C).
• High areal capacity (10.9 mAh cm⁻²) was achieved with high sulfur loading (7.9 mg cm⁻²) and a low electrolyte/sulfur ratio (9.0 µL mg⁻¹).

Conclusions:

• The W-W2C/G heterostructure serves as an effective catalytic interlayer for suppressing the shuttle effect in Li-S batteries.
• The unique electronic properties of the W-W2C interface significantly enhance polysulfide conversion and battery performance.
• This catalytic approach offers a promising strategy for developing high-performance and practical Li-S batteries.