PEDOT Nanowires Connecting Hollow Carbon Spheres Enable Long‐Cycling Zn‐Iodine Batteries

Abstract Aqueous Zn‐I 2 batteries (ZIBs) have attracted tremendous attention due to their high energy density and good safety. However, their applications are hindered by the lack of desirable I 2 hosts that can suppress polyiodide shuttle and improve I 2 /I − conversion simultaneously. Herein, a cathode host (P‐HCS) composed of hollow carbon spheres (HCS) and poly(3,4‐ethylenedioxythiophene) (PEDOT) nanowires is reported. The charge transfer from PEDOT to I 2 molecules induces partial conversion of I 2 to I 3 − which are confined between the π‐stacked interchains. Such strong interactions between PEDOT nanowire and I 3 − contribute to capturing polyiodides and suppressing their shuttles. Meanwhile, theoretical calculations reveal that PEDOT nanowires can promote I 2 /I − conversion reactions by lowering Gibbs free energy. Consequently, a ZIB with I 2 ‐P‐HCS cathode delivers a reversible capacity of 214 mAh g −1 at 0.1 A g −1 , while retaining 91% capacity and 99.8% coulombic efficiency over 47 000 cycles at 10 A g −1 . A high specific capacity and satisfying stability are also achieved at a high I 2 mass loading of 7.1 mg cm −2 , making PEDOT nanowires an ideal polymer that can realize fast I 2 /I − conversion reactions and shuttle suppression simultaneously.