Catalysis in Aqueous Zinc–Iodine Batteries: Materials and Mechanisms

Aqueous zinc–iodine (Zn–I2) batteries are promising for safe and sustainable energy storage, yet their application is constrained by sluggish iodine conversion kinetics and severe polyiodide shuttling. Recent advances have established cathode catalysis as a pivotal strategy to tackle these challenges. This review systematically analyzes the catalytic mechanisms and structure–performance relationships in catalyst design for Zn–I2 battery cathodes and categorizes the catalytic functions into three synergistic mechanisms, namely, chemisorption of polyiodides, acceleration of interfacial electron transfer via electronic structure engineering, and regulation of reaction pathways to circumvent intermediate accumulation. Our statistical analysis identifies the prevailing catalyst categories and metal elements in this field, and reveals a clear correlation between catalytic performance and the d-band center descriptor of metal active sites, providing a theoretical basis for understanding the observed structure–performance trends. The review further discusses design strategies including pore engineering, heterojunction construction, and coordination environment modulation. This review aims to provide theoretical guidance for the rational design of high-performance cathodes for Zn–I2 batteries and related conversion-type systems.