Cation‐Assisted Zinc Ion Desolvation for Long‐Cycled Zinc Metal Anodes at High Current Rates

Abstract Ionic salt additives have long been utilized to tailor the solvation structure of hydrated Zn 2+ in aqueous zinc batteries. However, the influence of cations on zinc ion solvation remains largely unexplored. In this work, for the first time, a cation‐assisted approach is presented and elucidated to promote the desolvation process of [Zn(H 2 O) 6 ] 2+ , thereby enabling highly reversible Zn plating/stripping at elevated current rates. Using sodium lactate as a proof‐of‐concept, it is demonstrated that Na + cations form a novel solvation structure that effectively competes for water molecules in the [Zn(H 2 O) 6 ] 2+ shell. This competition allows more lactate anions to be incorporated into the final solvation structure. The resulting water‐deficient interface on the Zn anode simultaneously suppresses water‐driven side reactions and directs Zn (002) deposition, mitigating dendrite formation. Consequently, the Zn anodes exhibit an exceptional cycling lifespan of 4500 h at a high current density of 20 mA cm −2 , along with stable performance even at 90% depth of discharge and a low negative‐to‐positive capacity ratio of 2.2 in full cells. This work provides a simple yet effective electrolyte engineering strategy to realize durable and deeply cyclable Zn metal anodes.