Tortuosity Engineering of Artificial Protective Layers for Enhancing the High‐Current‐Density Durability of Zn Anode

ABSTRACT Aqueous zinc‐ion batteries (AZIBs) are highly attractive for fast‐charging energy‐storage applications owing to the high ionic conductivity of aqueous electrolytes and the favorable properties of Zn metal anode. However, Zn anodes usually suffer from severe dendritic growth. Artificial solid electrolyte interphases (ASEIs) are widely employed to stabilize Zn deposition, yet conventional ASEIs are generally incompatible with high‐rate operation because their tortuous ion‐transport architectures hinder rapid Zn 2+ migration across the interface. Herein, we demonstrate the critical role of architectural tortuosity ( τ ) in governing Zn 2+ transport through ASEIs and propose a general strategy for constructing low‐ τ interphases via the in situ thermal decomposition of ammonium bicarbonate (NH 4 HCO 3 ). The resulting low‐ τ architecture dramatically enhances Zn 2+ transport, mitigates concentration polarization, and promotes uniform Zn deposition. Consequently, the protected Zn anode delivers exceptional stability, sustaining over 1000 h at 10 mA cm −2 and stable operation up to 40 mA cm −2 in symmetric cells. Full cells with I 2 cathode retain 93% capacity after 5000 cycles at 5 A g −1 . This work establishes τ reduction as a general principle for designing high‐rate and long‐life aqueous batteries.