Synergistic Interphase-Solvation Dual-Regulation Engineering via a Zwitterion Electrolyte Additive for Ultrastable Zn Metal Anodes

Aqueous Zn-metal batteries (AZMBs) are plagued by dendrite growth and parasitic reactions at the anode, limiting their commercial viability. While electrolyte additives offer promise, conventional monofunctional additives provide insufficient defense to Zn anodes. Herein, we introduce a zwitterionic 3-aminopropanesulfonic acid (APS) additive that enables an interphase-solvation dual-regulation (ISDR) mechanism. APS can specifically adsorb on Zn anodes, creating a water-poor and zincophilic electric double layer, which favors oriented (002) Zn deposition. Furthermore, APS alters the Zn 2+ solvation structure, breaking the original hydrogen bond network between H 2 O, and acts as a pH buffer during cycling. Consequently, Zn symmetric cells containing APS additive achieve ultralong cycling stability exceeding 5540 h at 0.5 mA cm –2, and Zn//Ca 0.24 V 2 O 5 ·0.83H 2 O full batteries retain 87.3% capacity after 1800 cycles at 3 A g –1 . Even at a high current density of 5 mA cm –2, the APS-containing electrolyte enables stable cycling for over 888 h. In addition, bending tests and the capacity to light up LED panels of pouch cells have proved its potential for application. The proposed ISDR mechanism offers a significant guideline for developing practical AZMBs.