Zwitterion-mediated interface chemistry for practical Zn-iodine batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc-iodine (Zn||I₂) batteries offer a cost-effective, safe, and sustainable alternative for energy storage.
• However, practical application is hindered by capacity degradation due to parasitic reactions at electrode interfaces.

Purpose of the Study:

• To develop a zwitterion-mediated interface chemistry to mitigate parasitic reactions in Zn||I₂ batteries.
• To enhance the stability and performance of aqueous Zn||I₂ batteries through electrolyte modification.

Main Methods:

• Utilized 1-butylsulfonate-3-methylimidazolium (BM) as a zwitterion electrolyte additive.
• Investigated the modulation of interface reactions at both negative (Zn) and positive (I₂) electrodes.
• Analyzed the formation of a dynamic dual-asymmetry interface at the negative electrode and reconfigured solvation at the positive electrode.

Main Results:

• The BM additive facilitated homogeneous zinc deposition and protected the Zn metal electrode.
• Interface reactions involving I₂ dissolution and polyiodide formation were deactivated at the positive electrode.
• Batteries with BM additive showed enhanced rate capability (135.5 mAh g^-1 at 20.0 A g^-1) and superior durability (91.9% capacity retention after 50,000 cycles).

Conclusions:

• Zwitterion-mediated interface chemistry effectively addresses key challenges in aqueous Zn||I₂ batteries.
• The developed strategy significantly improves the reliability and practical implementation of these sustainable batteries.