Recent Advances in Porous Cathode Hosts for Aqueous Zinc-Iodine Batteries

Aqueous zinc-iodine batteries (Zn-I₂) are promising candidates for large-scale energy storage due to their high theoretical capacity, intrinsic safety, and cost-effectiveness. However, their practical performance is severely hindered by the intrinsically low conductivity of I₂ and its discharge products, accompanied by the notorious polyiodide shuttle effect and sluggish redox kinetics. These drawbacks collectively compromise the rate capability, cycling stability, and energy density. As the I₂ cathode plays an indispensable role, engineering porous cathode hosts with tailored pore architectures and surface chemistries has emerged as a decisive strategy to overcome these bottlenecks. This review summarizes recent advances in porous materials for Zn-I₂ battery cathodes, highlighting their applications as iodine hosts, including porous carbons and their composites, metal-organic frameworks (MOFs), porous organic frameworks (POFs). Special emphasis is placed on how pore architecture affects iodine confinement, polyiodide retention, mass transport, and redox kinetics. Finally, future directions for the design of high-performance porous iodine hosts are discussed. This review provides insightful guidelines for the development of next-generation high-performance Zn-I₂ batteries.