Facet‐Driven Interfacial Regulation in a Heterostructured Dual‐Host for Highly Reversible Zinc–Iodine Batteries

ABSTRACT The development of aqueous zinc–iodine (Zn–I 2 ) batteries is constrained by severe polyiodide shuttling, dendrite growth, and the hydrogen evolution reaction (HER). Herein, a TiO 2 ‐coated TiN nanowire array electrode is designed through the synergistic integration of facet engineering and heterointerface construction, enabling the simultaneous suppression of these issues. Facet engineering allows the concurrent exposure of the thermodynamically stable TiO 2 (101) facets and the high‐energy (001) facets. The (001) facets exhibit stronger interactions with water molecules than those of (101) facets, significantly increasing the energy barrier for HER and accelerating the desolvation of hydrated Zn 2+ ions. Meanwhile, the 3D heterostructure establishes efficient electron/ion transport pathways, homogenizes the interfacial electric field, and mitigates surface polarization, thereby enabling uniform Zn deposition and effectively inhibiting dendrite growth at the anode. On the cathode side, the (001) facets can also enhance iodine species adsorption, while the heterointerfaces accelerate the catalytic conversion of polyiodides, effectively suppressing their dissolution and shuttling. As a result, the Zn–I 2 battery delivers a reversible capacity of 92.1 mAh g −1 with nearly 100% Coulombic efficiency after 10 000 cycles at 50 C. The synergistic effects of facets and heterostructures offer a new strategy for high‐performance aqueous Zn‐based energy storage systems.