Synergistic Adsorption of Zinc Ions and Polyiodide Species in Hydrazone‐Linked Covalent Organic Frameworks for High‐Performance Zinc–Iodine Batteries

ABSTRACT Aqueous zinc–iodine (Zn–I 2 ) batteries have demonstrated remarkable potential in extensive energy storage. Nevertheless, the practical application of Zn–I 2 batteries is constrained by the shuttle effect of polyiodide species. To address this issue, two hydrazone‐linked two‐dimensional (2D) covalent organic frameworks (COFs), named Por‐AQ‐COF and Por‐BT‐COF, were prepared under solvothermal conditions. Powder X‐ray diffraction, N 2 adsorption isotherm, and electron microscopy tests reveal the 2D tetrahedral structure geometry of both COFs with one‐dimensional (1D) channels. In particular, the abundant hydrazone groups in the channels of both COFs lead to their excellent Zn 2+ adsorption capacity, promoting their adsorption and activation of polyiodide species. This endows both Por‐AQ‐COF and Por‐BT‐COF with excellent Zn–I 2 batteries performance, achieving a capacity of 871 mA h g −1 at 2 A g −1 (corresponding to an energy density of 1045 W h kg −1 ), outstanding rate capability (554 mA h g −1 retained at 10 A g −1 with an energy density of 643 W h kg −1 ), and excellent cycling stability, surpass all previously reported host materials used in iodine electrode of Zn–I 2 batteries. This research would provide new insight into the design of porous host materials to inhibit the shuttle effect of polyiodide species for Zn–I 2 batteries with high performance and stability.