Bulk‐to‐IHP Zn Interphase Engineering With Mannitol Additive Enables (002)‐Textured Zn Plating With Suppressed Hydrogen Evolution Reaction for Ah‐Level Aqueous Zinc‐Iodine Pouch Cells

Abstract

ABSTRACT Aqueous zinc‐iodine batteries are promising contenders for next‐generation grid‐scale energy storage batteries. However, their deployment is hindered by zinc anode degradation at moderate cycling rates (0.5–2 C), including dendrite growth and parasitic hydrogen evolution reaction (HER), stemming from an unstable Zn/electrolyte interphase. Herein, a sugar alcohol‐based multifunctional additive of mannitol (ML), identified via theoretical screening based on molecular characteristics of electrostatic polarity, H 2 O binding energy, and LUMO level, is proposed to achieve comprehensive Zn/electrolyte interphase stabilization from the bulk phase to the inner Helmholtz plane (IHP). Leveraging abundant hydroxyl groups and good Zn 2+ affinity, ML disrupts the bulk hydrogen‐bond network and reconstructs Zn 2+ solvation structure, simultaneously suppressing proton‐hopping pathways and accelerating Zn 2+ desolvation. Moreover, robust chemisorption of ML molecules on both Zn (002) and Zn (101) planes modulates Zn deposition toward the thermodynamically stable (002) texture with enlarged grain size, thereby enabling dendrite‐free plating. Benefiting from these synergistic effects, Zn||I 2 full cells achieve an ultrahigh areal capacity of 6.5 mAh cm −2 over 3000 cycles at a practical rate of 1 C. Multiple Ah‐level Zn||I 2 pouch cells are also demonstrated, sustaining 1000 cycles with only 0.02% capacity decay per cycle, underscoring strong prospects for practical large‐scale application.