Realizing High Performance Four-Electron Zinc-Iodine Batteries with Acidic Eutectic Electrolyte

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Zinc-iodine (Zn-I₂) batteries offer multi-electron redox potential using halide ions and protons.
• Practical application is limited by corrosion, slow kinetics, and poor reversibility of iodine species.

Purpose of the Study:

• To engineer a deep eutectic solvent (DES) for high-performance Zn-I₂ batteries.
• To address challenges of corrosion and sluggish redox kinetics in Zn-I₂ systems.

Main Methods:

• Developed a ZPDES electrolyte using concentrated ZnCl₂ and H₃PO₄.
• Investigated hydrogen bonding (Cl⋯H─O) for corrosion mitigation.
• Analyzed proton-accelerated kinetics and anode surface effects.

Main Results:

• ZPDES effectively mitigates chloride and proton corrosion via hydrogen bonding.
• Achieved four-electron transfer by Cl^-, accelerated redox kinetics, and reduced I₃ ^- formation.
• Demonstrated enhanced Zn anode performance with promoted (002) texture and reduced by-products.

Conclusions:

• The engineered ZPDES electrolyte significantly improves Zn-I₂ battery performance.
• Achieved high specific capacity (576 mA h g^-1) and exceptional long-term stability (100% retention over 20,000 cycles).
• Highlights the potential of DES for advanced rechargeable battery technologies.