Ionic Covalent Organic Framework Membrane as Active Separator for Highly Reversible Zinc-Sulfur Battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Zinc-sulfur (Zn-S) batteries offer high theoretical energy density, low toxicity, and cost-effectiveness for energy storage.
• Polysulfide shuttling in Zn-S batteries causes capacity decay and limits practical lifespan.
• Effective separator design is crucial for overcoming limitations in sulfur-based batteries.

Purpose of the Study:

• To fabricate an ionic covalent organic framework (iCOF) membrane as an active separator for Zn-S batteries.
• To address the polysulfide shuttling issue and enhance the performance and longevity of Zn-S batteries.

Main Methods:

• Introduction of sulfonic acid groups to create an iCOF membrane with abundant negative charge sites.
• Utilizing a combination of size sieving and charge interaction to inhibit polysulfide crossover.
• Testing the iCOF membrane's efficacy in a Zn-S battery setup.

Main Results:

• The iCOF membrane effectively inhibited polysulfide crossover to the Zn anode while allowing metal ion transport.
• Zn-S batteries utilizing the iCOF separator demonstrated high performance with a low attenuation rate of 0.05% per cycle.
• The battery maintained performance over 300 cycles at 2.5 A g^-1.

Conclusions:

• Separator design is critical for advancing Zn-S battery technology.
• Functionalized framework materials, like the iCOF membrane, show significant potential for developing high-performance energy storage systems.
• The developed iCOF membrane offers a promising solution to polysulfide shuttling in Zn-S batteries.