EDTA‐Functionalized Metal‐Organic Framework With Synergistic Adsorption and Facilitated Iodine Conversion for High‐Performance Zinc‐Iodine Batteries

ABSTRACT

Aqueous zinc‐iodine batteries (ZIBs) have attracted significant attention due to intrinsic safety, low cost, and high energy density. However, practical deployment is hindered by the polyiodide shuttle effect, sluggish conversion kinetics, and instability of high‐valent iodine species. Accordingly, we design a multifunctional metal‐organic framework (MOF‐808‐EDTA) as a robust iodine host via a post‐synthetic modification strategy. Combined experimental and theoretical analyses demonstrate that EDTA functionalization preserves the crystalline framework and nanopores, ensuring spatial confinement of iodine species. Moreover, the strategy enhances the Lewis acidity of Zr−O clusters, optimizing the electronic structure of the MOF framework, and strengthens iodine chemical anchoring by multifunctional nitrogen sites. Through physicochemical confinement and electronic structure modulation, MOF‐808‐EDTA synergistically lowers the reaction barrier and promotes reversible iodine conversion. Meanwhile, nucleophilic Br ⁻ in the electrolyte activates and stabilizes I ⁺ , further extending the reaction pathway. Consequently, both two‐electron and four‐electron ZIBs exhibit rapid kinetics and excellent rate capability, delivering 47 000 cycles at 10 A g ⁻¹ and 100 000 cycles at 20 A g ⁻¹ , respectively. The present work designs a functionalized MOF‐based host via single‐molecule modification, constructs a reaction environment favorable for iodine species adsorption and conversion, offering a new paradigm for cathode design in multi‐electron conversion ZIBs.