Ultra‐Stable Zinc Anodes Facilitated by Hydrophilic Polypropylene Separators with Large Scale Production Capacity

Abstract Electrochemical Performance of aqueous Zn‐ion batteries (AZIBs) is prominently constrained by poor stability of zinc‐metal anodes. However, the use of conventional aqueous separators unfavorable to the uniform deposition of Zn metal and restricted cell cycle life, has hindered the large‐scale application of such battery systems. Here, a separator with hydrophobic/hydrophilic structural domains (marked as PP‐g‐AA) is reported, where the polypropylene (PP) polymer backbone permits partial blockage of water molecules and prevent side reactions, and the carboxyl functional groups in the grafted acrylic acid (AA) facilitate to well regulate the interfacial electric field and Zn 2+ ion concentration field, thus remarkably promotes homogenization of zinc ion flux, achieving dendritic‐free deposition of Zn 2+ . Moreover, the PP‐g‐AA separator sustains a long‐term cycling over 4000 h at a current density of 2 mA cm −2 with a high Coulombic efficiency of 99.6% achieved in Zn||Cu cells, which if assembled into Zn||Zn 0.27 V 2 O 5 ·nH 2 O (ZVO) cells would yield ≈100% retention for 1000 cycles. This research highlights that the strategy opens up a new avenue based on PP‐g‐AA for further decreasing the cost and promoting the industrial application of AZIBs.