Constructing matching interfaces by amorphous engineering for enhanced lithium ion transport in quasi‐solid‐state lithium‐iodine batteries

Quasi‐solid‐state lithium‐iodine (Li‐I2) batteries have shown prospects as their high theoretical capacity, high safety, and abundant iodine resources advantages. However, the interface between the crystalline filler and the flexible polymer skeleton of composite solid electrolytes exhibits inadequate bonding, leading to higher interface energy and sluggish migration dynamics of Li+. In this work, a continuous interface solid electrolyte is designed by combining the atomic structure rearrangement of MOF to achieve interface coupling between MOF and aramid fiber. Based on the experimental results and theoretical calculations, the amorphous engineering promotes Li+ migration and polyiodides confinement effect for Li‐I2 batteries. The batteries show a high capacity of 170.7 mAh g‐1 at 5 C and achieve a capacity retention rate of 97.8% after 450 cycles. More impressively, the batteries achieve a long life of 3000 cycles at the high current density of 20 C with a good capacity retention of 94.1%. This work reveals the mechanism of coupled interface with structure matching in Li+ migration and polyiodides integration process, providing guidance for the design of novel composite solid electrolytes to achieve high‐performance Li‐I2 batteries.