Dynamic Polyiodide‐Trapping and Proton‐Capturing Dual‐Network Engineering for High‐Areal‐Capacity, Long‐Cycling and High‐Temperature Zn─I 2 Batteries

Aqueous zinc–iodine (Zn─I 2 ) batteries demonstrate great potential in the large‐scale grid‐scale energy storage. However, severe polyiodide shuttling and interfacial parasitic reactions limit the practical application of aqueous Zn─I 2 batteries with high iodine loading. Here, aminonicotinic acid (AMI) is first introduced in this work to address these issues by dynamic polyiodide‐trapping and proton‐capturing dual‐network engineering. The abundant active sites on AMI effectively trap the I 3 − ions for inhibiting the polyiodide dissolution and migration in the electrolyte. Moreover, AMI reversibly captures H + ions and neutralizes OH − ions, thereby effectively mitigating pH fluctuations to suppress the interfacial side reaction on the Zn anode. Consequently, the Zn//Zn symmetrical battery demonstrates prolonged cycling stability over 7000 h at 1 mA cm −2 and 1 mAh cm −2 . The Zn─I 2 battery maintains stable cycling for over 2800 cycles based on an ultrahigh I 2 cathode loading of 23.8 mg cm −2 (3.1 mAh cm −2 ), and 3000 cycles at a high temperature of 50°C at 2 A g −1 . This work pioneers a novel electrolyte additive strategy for polyiodide‐trapping and pH‐buffering dual‐network engineering, providing a straightforward and innovative approach toward energy‐dense, endurable, and high‐temperature Zn─I 2 batteries.