Multifunctional iodine cathode binder design enabling high-performance zinc-iodine batteries: progress, challenges,...

Aqueous zinc-iodine batteries (AZIBs) have emerged as promising candidates for next-generation large-scale energy storage due to their high theoretical specific capacity, abundant raw materials, and intrinsic safety. However, their practical application remains hindered by several critical challenges arising from the polyiodide shuttle effect and insufficient mechanical stability during cycling at the iodine cathode side. The multifunctional iodine cathode binder design has therefore become a key strategy for improving the overall performance of iodine cathodes. This review first summarizes the fundamental reaction mechanisms and major limitations of iodine cathodes in AZIBs Then, the underlying causes of the shuttle effect, sluggish kinetics, and structural failure are discussed in relation to iodine redox chemistry. Also, recent progress in binder design is also highlighted, especially for the systems featuring polar functional groups, conductive frameworks, and multiple interaction sites. Lastly, current challenges together with future perspectives in binder optimization are discussed. This review is expected to provide useful guidance for rational binder design towards highly reliable, high-energy-density AZIBs.