Unlocking Durable and Sustainable Zinc-Iodine Batteries via Molecularly Engineered Polyiodide Reservoirs

Zinc-iodine batteries (ZIBs) are promising candidates for safe and sustainable energy storage but are hindered by polyiodide shuttling, leading to rapid capacity decay and limited cyclability. In this work, we propose a "polyiodide reservoirs" concept, utilizing iodophilic covalent organic cages to confine polyiodide through multiple noncovalent interactions. By precisely engineering the nitrogen-active site densities around 3D cavities, these cages evolve from open to near-enclosed structure, achieving molecular-level polyiodide entrapment. The optimized superphane cage (18 N-active sites) enables a ZIB with 90.1% capacity retention after 4000 cycles at 5 C, even under extreme conditions (58.9 wt% iodine content within the cage and an iodine area loading of 3.7 mg cm^-2 in the cathode). Importantly, the cage's solubility-driven regeneration capability retains 85.4% initial capacity over three reuse cycles. This work establishes covalent organic superphanes as a transformative platform for long-life ZIBs, offering a dual solution to shuttle suppression and electrode sustainability through structural confinement and dynamic recyclability.