Gelatinized starch as a low‐cost and bifunctional binder enables shuttle‐free aqueous zinc–iodine batteries

Abstract Rechargeable aqueous zinc–iodine (Zn–I 2 ) batteries are widely regarded as a promising contender for energy‐storage devices, due to their intrinsic safety, low cost, and high capacity. However, the severe shuttle effect of polyiodides and the large volume change of I 2 cathode induce severe capacity loss and poor electrochemical reversibility, hindering their commercial applications. Herein, we report that the low‐cost gelatinized starch (G‐starch) can be used as a bifunctional binder for Zn–I 2 batteries to circumvent the above problems simultaneously. Based on both calculation and experimental data, it is demonstrated that the double‐helix structure of G‐starch with both α‐1,4‐ and α‐1,6‐glycosidic bonds can strongly interact with polyiodides to suppress the shuttle effect. Moreover, the G‐starch with multiple hydrogen‐bonded cross‐linking networks exhibits a much‐enhanced adhesion ability and can buffer the volume expansion of active materials. In contrast, the traditional carboxymethyl cellulose sodium‐based aqueous binder lacks these capabilities. As a result, the G‐starch binder enables the aqueous Zn–I 2 battery to achieve a high reversible capacity of 212.4 mAh·g −1 at 0.2 A·g −1 after 1000 cycles and ultralong‐cycling life over 48,000 cycles with 135.4 mAh·g −1 and 89.6% capacity retention at 2 A·g −1 . This work develops a simple yet efficient strategy to construct high‐performance Zn–I 2 batteries.