Towards Ultra‐Stable Wide‐Temperature Zinc‐Ion Batteries by Using Ion‐Sieving Organic Framework Membrane

Abstract Aqueous zinc‐ion batteries (AZIBs) offer notable advantages in safety and cost‐efficiency, but Zn dendrite growth and unstable interfacial reactions hinder their commercial viability. A crucial factor in addressing these challenges lies in optimizing the separator to regulate ion transport and stabilize electrode interfaces. Herein, we propose a covalent organic framework (COF)‐based separator with quasi‐single‐ion conduction, specifically a Zn 2+ ‐substituted sulfonate COF (COF‐Zn) membrane, designed to tackle these issues. Featuring a high Zn transference number (0.87) and a thin 25 μm profile, the COF‐Zn separator allows for reduced electrolyte usage (20 μL mg −1 ) while effectively minimizing cathode dissolution. Its quasi‐single‐ion conductivity and electronegative properties improve Zn anode's stability by lowering water activity. This separator enables ultra‐stable AZIBs, as demonstrated in various full cells including Zn//4,5,9,10‐pyrenetetrone (PTO), Zn//I 2 and Zn//V 2 O 5 . Remarkably, the Zn//PTO cell achieves an energy density of 260 Wh kg −1 , 100 % capacity retention under reduced electrolyte conditions, and stable all‐weather cycling from −40 to +100 °C with a customized electrolyte.