Bio‐Inspired Aspartic Acid Additive Enables Stable Aqueous Zinc‐Metal Batteries

ABSTRACT Aqueous zinc‐metal batteries (AZMBs) offer compelling advantages in low cost and safety, yet their practical deployment is hindered by hydrogen evolution, corrosion, unstable electrode–electrolyte interfaces, and dendritic zinc (Zn) growth. Here, we report aspartic acid (ASP), a biocompatible and low‐cost additive, to stabilize the interfacial chemistry of Zn anodes in AZMBs. With dual carboxylate and amine functionalities, ASP acts as both a hydrogen‐bond donor and acceptor and preferentially adsorbs on the Zn anode, where it disrupts the interfacial hydrogen‐bond network, suppresses proton hopping and hydrogen evolution, and furnishes anchoring sites that homogenize Zn 2+ nucleation and growth. Combined experiments and calculations reveal that ASP partially replaces and reduces the population of interfacial free H 2 O molecules near the inner Helmholtz plane, and mitigates local electric‐field amplification and concentration gradients on the Zn anode surface. As a result, the stabilized interface simultaneously suppresses dendritic growth and corrosive issues, enabling Zn||Zn symmetric cells to cycle stably for >5000 h at 1 mA cm −2 and 1 mAh cm −2 , and for 2000 h at 5 mA cm −2 and 5 mAh cm −2 . Notably, it enables stable cycling of ∼0.6 Ah Zn||I 2 pouch cells for over 300 cycles with a high 98.9% capacity retention. Collectively, this bio‐inspired additive strategy establishes a practical and broadly applicable pathway to reversible AZMBs.