Tetraphenylethylene-Functionalized Zirconium Metal-Organic Frameworks Enabling Polyiodide Confinement for High-Performance Zinc-Iodine Batteries.

Tunable morphology and structure of metal-organic frameworks (MOFs) are critical for tailoring their physical-chemical characteristics and electrochemical functionality. In this work, a ligand extension strategy combined with a controlled etching process is employed in designing and synthesizing zirconium-based MOFs (Zr-MOFs). These structural optimizations increase active sites exposure and improve accessibility to π-conjugated transport channels. The obtained tetraphenylethylene-based Zr-MOFs exhibit excellent iodine adsorption capacity and strong confinement of polyiodides, enabling their use as cathode hosts in aqueous zinc-iodine batteries. The π-conjugated tetraphenylethylene ligand further increases the capacitance of batteries by promoting rapid electron dispersion and charge storage within the extended conjugated frameworks. In situ Raman spectroscopy and theoretical analyses reveal that the combination of physical confinement and chemical absorbance effects effectively stabilizes iodine species and governs the charge-discharge mechanism. As a result, the M4/I2 cathode exhibits excellent cycling stability, high multiplicity capacity, and reversible iodine redox kinetics. This research provides a generalizable strategy for constructing MOFs with controlled morphology and structure, offering new insights for the design of future high-performance aqueous battery systems.