An Adaptive Hydrophobic Interphase for Sustainable Aqueous Zinc Metal Batteries

ABSTRACT Aqueous Zn metal batteries (AZMBs) are promising for large‐scale energy storage, but their practical deployment is plagued by the issues of Zn anode involving non‐uniform plating/stripping, H 2 evolution, and low Zn utilization rate (ZUR). Herein, we report an adaptive hydrophobic interphase enabled by the adsorption/desorption of organic imidazolium cations that circumvent these challenges. Mechanistic studies reveal that typical monovalent inorganic cations (i.e., Na + , NH 4 + ) with higher hydration energy show considerably weaker electrostatic adsorption at the Zn interface than the selected organic cations, attributed to the charge‐screening effect of solvating‐water. Among the selected organic cations, imidazolium species outperform quaternary ammonium cations in the interface adsorption, with longer alkyl chains further enhancing this effect. The exemplified 1‐propyl‐3‐methylimidazolium (Pmim + ) cation creates a water‐depleted electric double layer that suppresses interfacial side reactions and homogenizes Zn 2+ plating. Moreover, Pmim + undergoes electric‐field‐induced desorption that allows the involvement of H 2 O during Zn 2+ stripping. The resultant dynamic hydrophobic interphase sustains compact Zn deposition and uniform stripping even at 25 mAh cm −2 (85.9% ZUR). Consequently, the formulated Pmim + ‐containing electrolyte enables the Zn electrode with a prolonged cycling life of 6000 h at 1 mA cm −2 and robust deep‐cycling performance, and supports stable operation of full AZMBs under harsh conditions.