Nano/Micro Metal-Organic Framework-Derived Porous Carbon with Rich Nitrogen Sites as Efficient Iodine Hosts for Aqueous Zinc-Iodine Batteries.

Nowadays, the low cost, superior safety, and long durability of aqueous zinc-iodine (Zn-I) batteries have garnered significant interest. Nevertheless, their practical use is limited by the inferior conductivity of iodine and the shuttle effect, resulting in suboptimal electrochemical behavior. In this work, a nano/micro zinc-based metal-organic framework (Zn-MOF) featuring a cubic morphology is employed for obtaining porous nitrogen-doped carbon (NC), which is reported as a cathode host for Zn-I batteries. Thanks to its porous architecture and high conductivity of NC, the optimized S3-1000 material achieves high iodine loading and enables rapid electron/ion transport. More importantly, the adsorption experiments combined with density functional theory (DFT) calculations reveal that the graphitic-N and pyridine-N moieties within the carbon matrix synergistically serve as active anchoring sites for iodine species, suppress polyiodide shuttle effects and accelerate redox kinetics during iodine conversion. As a result, the I@S3-1000 cathode achieves the highest specific capacity and superior cycle stability over 10,000 cycles, while in-situ characterization analysis confirms the reversible electrochemical mechanism. Soft pack battery and prototype flexible micro-battery based on the I@S3-1000 cathode are also fabricated and show excellent flexibility. This study promotes the development of MOF-derived carbon as iodine cathodes for advanced Zn-I batteries.