Dynamic Liquid Metal Catalysts for Boosted Lithium Polysulfides Redox Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Developing stable and efficient electrocatalysts is critical for lithium-sulfur (Li-S) batteries.
• Current electrocatalysts often suffer from long-term stability issues due to catalytic site degradation.
• Rapid kinetics of lithium polysulfides (LiPSs) conversion are essential for practical Li-S battery applications.

Purpose of the Study:

• To introduce a dynamic electrocatalytic strategy using liquid metal (gallium-tin, EGaSn) for Li-S batteries.
• To investigate the catalytic mechanism and stability of the liquid metal system for LiPSs redox reactions.
• To demonstrate the performance enhancement in a practical Li-S battery cell.

Main Methods:

• Theoretical simulations and microstructure experiment analysis were employed.
• The catalytic activity and stability of EGaSn were evaluated.
• A 2 Ah Li-S pouch cell was fabricated and tested.

Main Results:

• Tin (Sn) atoms dynamically distributed in the gallium (Ga) matrix were identified as the primary active catalytic centers.
• The liquid Ga matrix provided a dynamic environment, ensuring the long-term integrity of the catalytic system.
• The EGaSn-based Li-S cell achieved a specific energy density of 307.7 Wh kg⁻¹.

Conclusions:

• Liquid-phase binary alloys, specifically EGaSn, offer a promising avenue for developing stable and efficient electrocatalysts for Li-S batteries.
• The dynamic nature of the liquid metal catalyst overcomes the stability limitations of traditional solid catalysts.
• This strategy paves the way for high-specific-energy Li-S batteries.