Asymmetric Sulfonated Nanofibrous Separator for Simultaneously Stabilizing Zn Anodes and Accelerating Cathode Kinetics.

The practical deployment of aqueous zinc metal batteries requires the simultaneous stabilization of the Zn anode interface while maintaining high-capacity cathode operation. Creating an asymmetric interfacial environment featuring a water-poor region adjacent to the anode and a water-rich region adjacent to the cathode suppresses water-induced dendrite growth and corrosion at the anode while accelerating Zn2+/H2O insertion kinetics at the cathode. In this study, we report an asymmetric separator consisting of sulfonated poly(phenylene sulfide) (SPPS) nanofibers deposited onto a polypropylene (PP) substrate. Strong ion-dipole interactions between the sulfonate groups and hydrated Zn2+ promote the desolvation of [Zn(H2O)6]2+, reduce the number of coordinated water molecules, and consequently suppress dendritic Zn deposition. Meanwhile, water molecules enriched within the nanofibrous layer act as interfacial lubricants, facilitating Zn2+ intercalation/deintercalation and thereby accelerating cathode reaction kinetics while improving discharge capacity. Zn||Zn cells equipped with the asymmetric separator exhibit stable cycling for 6850 h at 1 mA cm-2, while Zn||Zn0.25V2O5 (ZVO) pouch cells retain 98.2% of their initial capacity after 250 cycles.