Highly Reversible Zinc Metal Anodes Enabled by Solvation Structure and Interface Chemistry Modulation

Abstract Aqueous Zn−ion batteries (AZIBs) promise appealing advantages including safety, affordability, and high volumetric energy density. However, rampant parasitic reactions and dendrite growth result in inadequate Zn reversibility. Here, a biocompatible additive, L‐asparagine (Asp), in a low‐cost aqueous electrolyte, is introduced to address these concerns. Combining substantive verification tests and theoretical calculations, it is demonstrated that an Asp‐containing ZnSO4 electrolyte can create a robust nanostructured solid‐electrolyte interface (SEI) by simultaneously modulating the Zn2+ solvation structure and optimizing the metal‐molecule interface, which enables dense Zn deposition. The optimized electrolyte supports excellent Zn reversibility by achieving dendrite‐free Zn plating/stripping over 240 h at a high Zn utilization of 85.5% in the symmetrical cell and an average 99.6% Coulombic efficiency for over 1600 cycles in the asymmetrical cell. Adequate full‐cell performance is demonstrated with a poly(3,4‐ethylenedioxythiophene) intercalated vanadium oxide (PEDOT‐V2O5) cathode, which delivers a high areal capacity of 4.62 mAh cm−2 and holds 84.4% capacity retention over 200 cycles under practical conditions with an ultrathin Zn anode (20 µm) and a low negative/positive capacity ratio (≈2.4). This electrolyte engineering strategy provides new insights into regulating the anode/electrolyte interfacial chemistries toward high‐performance AZIBs.