One-Step Integration of Sulfonated Polymer Films with Separators for Shuttle Mitigation in Lithium-Sulfur Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Interfacial polymerization (IP) is a cost-effective method for thin polymer film fabrication.
• Lithium-sulfur batteries face challenges with polysulfide shuttling and capacity fade.
• Separator modification is crucial for enhancing battery performance.

Purpose of the Study:

• To develop a charge-selective sulfonated thin-film coating for lithium-sulfur battery separators.
• To improve selective transport and suppress polysulfide shuttling.
• To overcome the trade-off between rate performance and capacity retention.

Main Methods:

• A one-step interfacial polymerization reaction between triacyl chloride and sulfonated diamine monomers.
• Fractional substitution of monomers to control film cross-link density and uniformity.
• Addition of a small amount of nonsulfonated diamine to enhance film coverage.

Main Results:

• The sulfonated thin-film coating effectively suppressed polysulfide shuttling, enhancing capacity retention.
• Initial dense films compromised lithium ion conduction, impacting rate performance.
• Optimized films with controlled cross-linking and uniform coverage broke the rate-capacity trade-off.
• Achieved 711.6 mAh g-1 after 200 cycles at 0.5C and >800 mAh g-1 at 2C.

Conclusions:

• Optimized interfacial polymerization yields thin-film coatings that significantly improve lithium-sulfur battery performance.
• The developed coating addresses key challenges like polysulfide shuttling and the rate-capacity retention trade-off.
• This approach offers a promising strategy for advanced battery separator design.