Efficient I ⁻ /I ₃ ⁻ /I ₂ Conversion and Shuttle‐Suppression in High‐Rate Ah‐Level Zinc‐Iodine Batteries Enabled by Bifunctional Confined‐Catalyst ZrB ₂ /AC Host

Rechargeable aqueous Zn||I₂ batteries have received significant attention for the high energy density, inherent safety, and ecological friendliness. However, the sluggish iodine redox kinetics and the formation of highly soluble polyiodide (I₃ ⁻ and I₅ ⁻) seriously affect the rate capability and cycling stability of Zn||I₂ battery. Herein, ZrB₂ is synthesized as a catalyst host for polyiodide conversion, where unsaturated surface Zr atoms provide Lewis-acid sites that enable strong interaction with polyiodide species. These sites not only confine polyiodide anions through strong adsorption to suppress polyiodide shuttling, but also catalyze their stepwise conversion from I⁻ to I₃ ⁻ and further to I₂ during charging, thereby reducing the energy barrier and improving iodine utilization. Consequently, the Zn||I₂@ZrB₂/AC full cell displays remarkable rate performance, retaining 80.5% of the capacity as the current density increases from 1 to 10 A g⁻¹. Remarkably, the full cells exhibit exceptionally long cycle life of 50,000 cycles with negligible capacity decay. The Zn||I₂@ZrB₂/AC pouch cell with a high I₂ mass loading of 33 mg cm⁻² maintains a stable capacity of 1.2 Ah over 600 cycles (more than 1400 h).