In Situ Constructing a Film‐Coated 3D Porous Zn Anode by Iodine Etching Strategy Toward Horizontally Arranged Dendrite‐Free Zn Deposition

Abstract Zn metal anode has drawn tremendous attention owing to its low cost and high volumetric capacity advantages. However, the commercial application of zinc‐based batteries is greatly deterred by Zn dendrite and severe side reactions. Interface modification is one of the most effective strategies to solve these issues. Herein, a facile iodine etching strategy to in situ construct a film‐coated 3D porous Zn anode is first proposed, which significantly reduces the nucleation overpotential of Zn while suppressing side reactions, thus resulting in uniform Zn deposition. Benefiting from the dual protection of surface coating and 3D porous Zn anode, the symmetric cell displays a long lifespan of over 5000 h at 1 mA cm –2 , ≈40 times of bare Zn anode. The asymmetric cell with modified Zn anode also delivers excellent cycling stability for over 2000 cycles to achieve a high average Coulombic efficiency of 99.87%. Moreover, the capacity retention of a full battery coupled with ammonium vanadate cathode after 5000 cycles is up to 97.3%, which is much more stable than the bare Zn anode under the same condition (20%). Such a novel interfacial modification method provides a new perspective for the realization of stable metal electrodes.