Heteroatom-Modulated Asymmetric Cobalt Single-Atom Catalysts on MOF-Derived Carbon Enabling Durable Zinc-Iodine Batteries

The rational design of catalytic host materials with optimized electronic structures and confined architectures is crucial for addressing the shuttle effect and sluggish kinetics in aqueous zinc-iodine batteries. In this study, an asymmetric cobalt single-atom catalyst is developed by anchoring Co−N₃P₁ sites on a nitrogen-phosphorus co-doped carbon matrix (Co−N−PC) derived from metal–organic frameworks (MOFs). The coordination engineering of Co centers via phosphorus incorporation disrupts the symmetry of conventional Co−N₄ configurations, enhancing charge redistribution and reducing the energy barrier for iodine dissociation as confirmed by density functional theory calculations. Systematic optimization reveals that moderate Co and P doping balances active sites and electronic conductivity, achieving strong chemical adsorption of polyiodides while maintaining structural stability. In situ Raman and UV–Vis spectroscopies confirm effective confinement of iodine species and reversible iodine conversion. The optimized C3/I₂ cathode exhibits exceptional cyclability, retaining a specific capacity of 100.6 mA h g⁻¹ after 50,000 cycles at 5 A g⁻¹. Furthermore, practical applicability is demonstrated in flexible soft-pack batteries and 3D-printed/screen-printed micro-batteries, showing its potential for scalable energy storage. This work presents a heteroatom-modulation strategy for designing efficient catalytic hosts in conversion-type batteries.