Novel zinc-compound iodine battery chemistry

Aqueous zinc–iodine batteries provide a safe and low-cost option for large-scale energy storage, but their development has been hindered by polyiodide shuttling and low operating voltage.
This study introduces a new zinc-compound iodine chemistry that combines a ZnC₂O₄·2H₂O (ZCO) conversion-type anode with a dual-functional K₂C₂O₄ electrolyte. The system enables a reversible solid-to-solid transition between ZCO and metallic zinc, which lowers the anode potential and increases the working voltage. During discharge, I⁻ and H₂O compete with C₂O₄²⁻ to coordinate with Zn²⁺, activating a dual storage mechanism at the anode. In parallel, oxalate anions form charge-transfer interactions with iodine species, effectively suppressing polyiodide formation and transport. The resulting ZCO–I₂ battery exhibits reduced self-discharge and excellent long-term cycling stability.
This work provides a new perspective for designing conversion-type anodes and multifunctional electrolytes, offering a promising pathway for advancing aqueous iodine-based energy-storage systems. The work entitled “Zinc-Compound Iodine Battery Chemistry with Dual Functional Oxalate-Based Electrolyte” was published in Advanced Powder Materials (Available online on 21 November 2025).