Click Chemistry-Inspired Fixation Catalysis for Long-Life Zinc-Iodine Batteries.

Zinc-iodine (Zn-I2) batteries are promising candidates for high-performance and cost-effective energy storage, yet their practical deployment is hindered by severe polyiodide shuttling and limited redox kinetics. To overcome this bottleneck at its core, a molecular-level fixation catalysis strategy-inspired by click chemistry principles is presented-that transcends the limitations of conventional adsorption and heterogeneous catalysis. Inspired by the selectivity and efficiency of click reactions, a Cp(Fe(CO)2)2-derived molecular catalyst (Fe-Cp) is designed that forms directional and robust Fe─I coordination bonds, locking iodine species into stable Fe-CpI complexes. Beyond anchoring, Fe-Cp uniquely enables axial electron transfer, facilitating reversible charge redistribution and dynamic iodine redox conversion beyond the reach of surface-confined systems. This dual-function mechanism not only suppresses the polyiodide shuttle but also dynamically regulates the electron redistribution at the catalytic interface, fundamentally enhancing reaction kinetics. Benefiting from this design, the Zn-I2 batteries deliver an exceptional cycling lifespan of 63 000 cycles at 20 A g-1 with 95% capacity retention and ≈100% Coulombic efficiency. Remarkably, even under a high mass loading of 20 mg cm-2 in pouch Zn-I2 cells, the system maintains a high areal capacity of 3.3 mAh cm-2 and ≈100% capacity retention even after 2000 cycles.