Structural Ordering and Polarizable Al ³⁺ Solvation Induced via Amphiphilic Zwitterion for Highly‐Reversible Zn–Al Alloy Anodes

Aqueous aluminum‐ion batteries face significant challenges in achieving stable plating/stripping owing to issues such as hydrogen evolution and corrosion. Although the in situ formation of Zn‐Al alloys via Zn anodes and Al 3+ ‐based electrolytes enables a suitable operating potential, this approach is hindered by cycling deactivation caused by uneven deposition and side reactions. Herein, we employ an amphiphilic zwitterion (ZI‐10) as an electrolyte additive to enhance the stability of Zn–Al alloy anodes. Small‐angle X‐ray scattering (SAXS) and sum frequency generation (SFG) spectroscopy reveal that the self‐assembly of ZI‐10 forms ordered aggregates, thereby constructing a dual‐layered electric double layer (EDL) that excludes water from the electrode interface while facilitating reversible plating/stripping. The zwitterionic chelation further induces a polarizable Al 3+ solvation shell that reduces the energy barrier for charge transfer. Ultimately, Zn–Al||Zn–Al symmetric cells achieve >2500 h of stable operation at 1 mA cm −2 and 1 mAh cm −2 , outperforming the recently reported counterparts. Full cells paired with MnVO cathodes sustain stable cycling even under 10 mg cm −2 cathode loading, while Zn–Al||I 2 full cells further demonstrate exceptional long‐term durability. This work offers insights into the role of amphiphilic zwitterions in tailoring electrolyte nanostructure and interfacial reaction kinetics.