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