Dual Helmholtz Plane Engineering via Hydrogen‐Bonded Binary Additives Enables Oriented Deposition of Zinc Metal Anodes

Uncontrolled dendrite growth and water‐induced parasitic reactions at the Zn/electrolyte interface limit the practical application of aqueous zinc‐ion batteries. Interfacial Helmholtz‐structure regulation is an effective strategy for stabilizing Zn metal anodes. Herein, we report a hydrogen‐bond‐mediated binary additive system, composed of methyl 3‐hydroxyisoxazole‐5‐carboxylate and cytidine 5′‐monophosphate disodium salt (MHIC‐CMP), to reconstruct the dual Helmholtz planes and modulate interfacial electrochemistry. Both MHIC and CMP additives jointly reorganize the primary solvation structure and coordination environment in the outer Helmholtz plane, with MHIC predominantly governing the interfacial solvation process, while CMP molecules enriched with ribose hydroxyl groups preferentially anchor onto the Zn surface, inducing the co‐adsorption of MHIC through intermolecular hydrogen bonding to form a water‐deficient inner Helmholtz plane. This dual‐plane regulation suppresses water activity and guides compact Zn deposition along the Zn (101) plane, mitigating dendrite formation and parasitic reactions. Therefore, Zn||Zn symmetric cells deliver an ultralong lifespan of 4100 h at 1 mA cm −2 /1 mAh cm −2 and stable cycling for 1200 h at 10 mA cm −2 /10 mAh cm −2 . Moreover, Zn||MnO 2 full cells exhibit improved cycling stability and capacity retention. This work highlights dual Helmholtz plane engineering as an effective design for stabilizing metal anodes in aqueous batteries.