Preiodization Unlocks an Orbital‐Regulated Cascade Redox Chemistry for High‐Capacity Zinc‐Iodine Batteries

ABSTRACT

Zinc‐iodine (Zn‐I ₂ ) batteries are considered as competitive candidates for large‐scale energy storage devices due to their high safety and low cost, but slow iodine conversion kinetics and limited theoretical capacity have always hindered their commercial application. In this work, the preiodization strategy successfully activates the iodine redox conversion of VS ₂ catalytic electrodes (I‐VS ₂ /I ₂ ) and achieves a cascade of I ⁰ /I ⁻ redox and Zn ²⁺ intercalation/deintercalation reactions. Theoretical and experimental analyses indicate that preiodization optimizes the V─I orbital coupling strength and electron exchange by effectively regulating the bonding and antibonding states occupation, which promotes the iodine redox conversion and inhibits polyiodide formation. Moreover, the cascade of I ⁰ /I ⁻ redox conversion and Zn ²⁺ intercalation/deintercalation reactions contributes to exceeding the theoretical capacity limitation of conventional Zn‐I ₂ batteries. Consequently, high‐capacity (372 mAh g ⁻¹ at 0.5 A g ⁻¹ ) and cycling‐stable (86% capacity retention after 4000 cycles) Zn‐I ₂ batteries were acquired. The work offers an essential inspiration for investigating in depth the orbital electronic structure‐catalytic performance relationship.