Multifunctional Zwitterionic Regulation for Long-Term Stability of Zinc Metal Anodes

The practical application of aqueous zinc-ion batteries is hindered by the interfacial instability of zinc anodes, whose parasitic reactions, such as dendrite growth, hydrogen evolution, and corrosion, lead to a rapid performance degradation. Here, we propose a multifunctional electrolyte additive strategy by introducing a zwitterionic molecule, 3-(amidinothio)-1-propanesulfonic acid (APSA), to achieve synergistic regulation of the Zn anode interface. The APSA spontaneously adsorbs onto the Zn surface, where its Zn-affinitive sites (e.g., sulfonate groups) optimize the Zn2+ solvation structure, while its zwitterionic groups buffer interfacial pH fluctuations, thereby triggering the in situ formation of a robust solid electrolyte interphase (SEI). This interfacial layer effectively suppresses parasitic reactions and promotes a uniform Zn deposition. Benefiting from these mechanisms, APSA-containing electrolytes enable Zn/Zn symmetric cells to cycle stably for over 4300 h. Furthermore, Zn∥MnO2 batteries employing the APSA electrolyte deliver 153.8 mA h g–1 after 500 cycles at 1 A g–1. This work provides a new molecular engineering pathway for achieving multifunctional and synergistic regulation of Zn anode interfaces.