Extension of Aqueous Zinc Battery Life Using a Robust and Hydrophilic Polymer Separator

Abstract The use of zinc (Zn) metal as an anode in aqueous batteries offers an eco‐friendly and cost‐effective energy storage solution. However, Zn dendrite formation severely restricts the cycle life of the battery toward practical application. Herein, a commercially hydrophilic polytetrafluoroethylene (PTFE) membrane is demonstrated as a separator to significantly extend the cycle life of the Zn metal anode. In contrast with the conventional fragile glass fiber separator, a wetted PTFE separator exhibited high mechanical strength (stress of 34.3 MPa at 41.4% strain) and favorable hydrophilicity, which both efficiently suppress dendrite growth. The uniform and robust pore structures are proven to facilitate a homogeneous Zn 2+ ion flux and a high transfer number of Zn 2+ (0.81), which has guaranteed reversible Zn plating/stripping. As a proof of concept, the PTFE separator extended the cycle life considerably to over 3000 h and promoted a Zn plating/stripping efficiency of 99.5% in the unmodified 2 m ZnSO 4 aqueous electrolyte. This advancement underscores the significant potential of the PTFE separator for enhancement of the cycling durability of aqueous zinc‐ion batteries (AZIBs).