Dynamic pH Regulation and Interfacial Ion Redistribution via Molecular Buffering for Dendrite‐Free Zn Metal Anodes

Aqueous Zn ion batteries suffer from irreversible anode degradation caused by hydrogen evolution reaction (HER)‐driven electrolyte alkalization and non‐uniform Zn deposition. Here, a bi‐functional buffer additive is proposed that synergistically couples pH regulation and interfacial ion‐redistribution. The buffer additive maintains electrolyte with a self‐regulated pH (≈3) through proton donor‐acceptor equilibria, effectively scavenging hydroxyl ions to prevent Zn passivation, while inducing preferential Na⁺ adsorption at protrusions to enforce planar Zn deposition via charge screening effects. This dual mechanism enables an ultralow nucleation overpotential (24.5 mV) and an ultrahigh Coulombic efficiency (99.9% over 12 000 cycles) in Cu–Zn half cells. Full cells with NaV 3 O 8 cathodes achieve 93% capacity retention after 3000 cycles at 10 A g −1 , while pouch cells (20.89 mg cm −2 cathode) retain 81.6% capacity over 300 cycles at 1 A g −1 . This work establishes a universal paradigm for stabilizing Zn anodes through coupled thermodynamic and kinetic regulation, positioning Zn‐ion batteries as viable candidates for grid‐scale energy storage.