Regulating Interfacial Dynamic Self‐Adjusting Hydrophobic Layer via Cationic Molecular Structure for Ultra‐Stable Zinc Metal Anode

Abstract The structure of solution additives significantly affects the polarization and dendrite behavior of metal batteries. In this study, we propose, for the first time, the “hydrophilic‐lipophilic balance (HLB) value‐spatial configuration synergistic regulation” strategy by selecting cations with different structures as additives, successfully revealing the structure‐activity relationship between additive structures and the stability of the anode interface adsorption layer. Among them, the butyltrimethylammonium chloride additive (ADD4), which has a low HLB value and a linear structure, exhibits the most stable interfacial structure. The stable hydrophobic region formed by its spontaneous aggregation and assembly shows a repulsive effect on hydrated protons. The constructed protective layer can effectively reduce overpotential and inhibit the formation of by‐products. The battery with ADD4 exhibits excellent stability, with over 1700 cycles and an average Coulombic efficiency of 99.7%. The full laboratory cells and pouch cells can also maintain very good cyclability, verifying their feasibility for practical applications. This study emphasizes that exploring the relationship between the hydrophilic‐hydrophobic properties, microstructure of additive ions, and the stability of the adsorption layer is crucial for designing appropriate electrolyte‐electrode interface layers.