Engineering Electron Cloud Density to Achieve Bifunctional Electrophilic Hosts for Aqueous Zn‐I2 Batteries with Ultrahigh Rate Property and Cycling Stability

For I2 cathodes, the severe polyiodide shuttling and sluggish reaction kinetics result in unsatisfactory cycling lifespan and rate performance. Herein, a bifunctional electrophilic host is designed by engineering the electron cloud density to effectively anchor electron‐rich polyiodides. Three configurations are initially screened through density functional theory simulations, which reveal that Si─O bonds can firmly anchor I3− via Si electrophilic centers. Owing to the considerably lower electronegativity of Si (1.90) than that of O (3.44), electrons surrounding Si atoms are strongly drawn toward O atoms, creating Si electrophilic centers. Specifically, I3− adsorbed onto Si─O bonds exhibits a favorable orbital configuration with a low energy gap, thereby kinetically enhancing polyiodide conversion. As a proof of concept, SiO2 nanocrystals embedded in conductive microporous bio‐carbon are derived from poplar flowers. The resulting I2 cathodes demonstrate excellent cycling stability over 110 000 cycles at 4 A g−1 and a high rate performance with a capacity of 123.8 mAh g−1 at 100 C. Furthermore, the I2 cathode with a loading as high as 36.5 mg cm−2 can also perform well in terms of 127.6 mAh g−1 after 100 cycles. This study presents a new route for the rational design of high‐efficiency and sustainable hosts for I2 cathodes.