Hydrogen Bond Reconstruction Triggered by Diethylenetriaminepentaacetic Acid Suppresses Zinc Dendrites and Polyiodide Shuttle for Stable Zinc-Iodine Batteries

<title>Abstract</title> <p> Zinc-iodine batteries attract interest for grid storage due to low cost and high safety, but their practical deployment is hindered by the coupled failure cycle of dendrite growth and polyiodide shuttling. Herein, diethylenetriaminepentaacetic acid (DTPA) is introduced as a modifier for polyacrylamide (PAM) gel electrolytes. In the bulk, DTPA forms dynamic hydrogen bonds with PAM chains, extending fracture strain beyond 1400% and establishing continuous ionic pathways. DTPA displaces coordinated water from the Zn ²⁺ solvation sheath via multidentate coordination, reducing water activity and suppressing side reactions. On the interface of zinc anode, DTPA spontaneously adsorbs to form a coordination layer, directing Zn deposition along the (002) plane and yielding dendrite-free morphology. While on the interface of I ₂ cathode, negatively charged carboxylate groups impose electrostatic repulsion on polyiodide anions, which together with physical confinement of the PAM network blocks polyiodide shuttling. The Zn||I ₂ full cells deliver 14000 cycles at 5 A g ^− 1 with negligible capacity fade, demonstrating a great potential of hydrogen bond reconstruction strategy for developing stable zinc-iodine batteries. </p>