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 VS2 reinforces interaction with I-3(-) and achieves catalytic conversion of iodine, ameliorating self-discharge, and accelerating kinetics. Zinc-iodine batteries featuring LiVS2 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.