Synergistic Strategy of Targeted Capture and Potential Responsive Release for High‐Performance Zinc‐Iodine Batteries

The shuttle effect, arising from the dissolution and migration of polyiodide species, severely hinders the practical application of high-energy-density zinc-iodine (Zn─I₂) batteries. Conventional carbon-based cathode materials, relying on weak physical adsorption, fail to effectively confine iodine species. To address this issue, a synergistic strategy is proposed that combines the targeted capture of I^- to form BiOI with the potential responsive release of I^- from BiOI during the reduction of Bi³⁺ to Bi. This approach enables a dynamic and directional capture-release process at a potential lower than that required for the reduction of I₂. This methodology is validated through ex situ spectroscopic analysis and Density functional theory (DFT) calculations. This decoupled mechanism suppresses polyiodide formation and ensures efficient cathode reversibility. The incorporation of Bi₂O₃ also introduces an additional redox couple, contributing extra capacity to the battery. The battery not only efficiently suppresses the inherent side reaction issues of zinc-iodine batteries, but also achieves a considerably high capacity level in the field of iodine single-electron conversion. This work provides a universal design principle for manipulating iodine electrochemistry, paving the way for high-energy, long-lifespan halogen-based batteries.