High Hydrophobic Layer with Nanoscaled Cationic Confinement Enables Stable Zinc Anodes

Water's Janus‐faced functionality as both an ion‐transport medium and parasitic‐electrochemistry instigator creates an irreconcilable interfacial dilemma for Zn anodes in aqueous electrolytes. Herein, a hierarchical optimization strategy is proposed, integrating dual collaborative mechanisms: hydrophobic shielding and cationic regulation, achieved by functionalizing Zn anodes with an alkylated silane‐based quaternary ammonium salt (Zn@SiONH + ‐C 18 ). The hydrophobic octadecyl chains suppress H 2 O‐induced corrosion and hydrogen evolution, while ─NH 4 + groups enhance Zn 2+ deposition kinetics via the electrostatic repulsion effect and anchor SO 4 2‐ to mitigate passivation reaction. Simultaneously, the siloxane‐derived Si‐O‐Zn skeleton with cross‐linked Si‐O‐Si networks ensures mechanical robustness of the interface, fundamentally inhibiting dendrite formation. Consequently, the Zn@SiONH + ‐C 18 symmetric cells exhibit exceptional cycling over 3400 h (1 mA cm −2 ) and 2800 h (5 mA cm −2 ) at 1 mAh cm −2 . Notably, the Zn@SiONH + ‐C 18 anode sustains 1000 h under a 55.6% depth of discharge (DOD, 10 mAh cm −2 ) and achieves a high DOD of 92% (16.6 mAh cm −2 ). When paired with a MnO 2 cathode, the full battery retains 63.2% capacity after 10,000 cycles at 10C. This specific molecular‐layer engineering strategy, which simultaneously addresses dendrite suppression and interfacial stabilization, establishes a paradigm for developing sustainable aqueous metal batteries.