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

Rechargeable aqueous zinc–iodine (Zn–I₂) 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 I₂ 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–I₂ 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–I₂ 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–I₂ batteries.

Graphical Abstract