Cation-Conduction Dominated Hydrogels for Durable Zinc-Iodine Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Zinc-iodine batteries offer high energy density but suffer from limited lifespan due to Zn anode dendrites and polyiodide shuttling.
• Improving the stability of both the anode and cathode is crucial for practical aqueous energy storage.

Purpose of the Study:

• To design a novel hydrogel electrolyte that enhances the stability of zinc anodes and iodine cathodes in zinc-iodine batteries.
• To address dendrite growth, side reactions, and polyiodide shuttling for improved battery performance and longevity.

Main Methods:

• Development of a cation-conduction dominated hydrogel electrolyte with covalently anchored anions.
• Investigation of zinc ion transference number, Zn nucleation, solvation structure, and hydrogen bond networks.
• Evaluation of electrostatic repulsion effects on polyiodides at the cathode.

Main Results:

• Achieved a high zinc ion transference number of 0.81 within the hydrogel electrolyte.
• Guided epitaxial Zn nucleation and suppressed Zn anode corrosion.
• Demonstrated hindered loss of iodine active material via electrostatic repulsion.
• Observed high reversibility, low self-discharge, and extended lifespan in zinc-iodine batteries.

Conclusions:

• The cation-conductive hydrogel electrolyte effectively stabilizes both the zinc anode and iodine cathode.
• This electrolyte design offers a promising strategy for developing high-performance and long-lasting aqueous zinc-iodine batteries.