Electrostatically Coupled High-Modulus Interphase with Synergistic Anion–Cation Regulation for Stable Zn Anodes

Abstract Aqueous zinc batteries (AZBs) are promising for large-scale and safe energy storage, yet their practical application is hindered by dendrite growth, corrosion, and parasitic side reactions on Zn anodes. Herein, a high-modulus, charge-rich interfacial layer is constructed through electrostatic coupling of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) with polyaminopropyl biguanide (PB) to stabilize Zn anodes. The coupled interfacial layer synergistically integrates anion–cation regulation with enhanced mechanical robustness, accelerating Zn2+ desolvation, regulating ion flux, and suppressing side reactions. Meanwhile, the high-modulus yet tough interfacial layer effectively mitigates dendrite growth and buffers volume fluctuations during repeated Zn plating/stripping. As a result, the symmetric cells deliver an ultralong lifespan of over 2200 h at 1.0 mA cm–2 and 1.0 mAh cm–2, and maintain stable operation for over 800 h at 20.0 mA cm–2 with 10.0 mAh cm–2. Zn||Cu cells achieve highly reversible plating/stripping over 2000 cycles, and the Zn||NaV3O8 full cells demonstrate excellent rate capability and long-term cycling over 3500 cycles. This work provides a promising strategy for enhancing the anode stability of high-performance aqueous zinc batteries.