Lithiation enhances electrocatalytic iodine conversion and polyiodide confinement in iodine host for zinc-iodine batteries

Aqueous static zinc-iodine batteries attract tremendous attention because of their abundant reserves of iodine, nonflammable electrolyte, and facile assembly. Currently, scientific challenges for static zinc-iodine batteries include self-discharge and sluggish kinetics. Herein, a lithiation approach for the iodine host to suppress the shuttle effect and catalyze iodine conversion is reported. Through regulating the d- and p-band center and lowering the I${}^{-}$/I${}^0$ conversion barrier, Li${}^{+}$ intercalation into VS${}_2$ reinforces interaction with I${}_3$${}^{-}$ and achieves catalytic conversion of iodine, ameliorating self-discharge, and accelerating kinetics. Zinc-iodine batteries featuring LiVS${}_2$ as the iodine host reach a high iodine utilization, high Coulombic efficiencies, and a long cyclic lifespan. Notably, the performance enhancement mechanism is the thermodynamically favorable iodine conversion reaction, inhibition of the I${}_3$${}^{-}$ appearance, and promotion of I${}_3$${}^{-}$ consumption due to the Li${}^{+}$ insertion. The findings provide fundamental insights into tackling issues of static zinc-iodine batteries. (© 2023 Wiley‐VCH GmbH)