Pore‐Engineered Carbon Cloth via Thermal Activation for Shuttle‐Free Zinc–Iodine Batteries with Ultralow Self‐Discharge

Zinc–iodine (Zn–I 2 ) batteries are promising for grid‐scale energy storage but suffer from severe polyiodide shuttling and rapid self‐discharge. Here, a thermally activated carbon cloth (CC450) that simultaneously addresses iodine confinement and reaction kinetics through precisely engineered hierarchical porosity is reported. By optimizing oxidative calcination at 450 °C in air, CC450 develops a unique pore structure with nanopores for strong I 3 − adsorption and interconnected macropores for rapid ion transport, while maintaining the intrinsic conductivity and flexibility of CC. The CC450 cathode achieves an exceptional balance of performance metrics: high areal capacity, ultralow self‐discharge (3.05% in 24 h), and outstanding cycling stability (94.63% capacity retention over 1000 cycles), which represents the best‐reported performance for binder‐free carbon electrodes in Zn–I 2 batteries. Mechanistic studies reveal that CC450's 12‐fold reduction in charge‐transfer resistance and low activation energy for I − oxidation stem from its optimal surface chemistry and pore hierarchy. The self‐discharge tests and UV–vis spectroscopy confirm efficient iodine shuttle suppression. Unlike complex nanomaterial‐based hosts, CC450 is fabricated through a scalable ambient‐air process, offering immediate industrial relevance. This work provides critical insights into pore‐engineered carbon hosts for metal–iodine batteries and establishes a generalizable strategy for achieving high‐energy, long‐life energy storage systems.