Lithiation Enhances Electrocatalytic Iodine Conversion and Polyiodide Confinement in Iodine Host for Zinc–Iodine Batteries

Abstract

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−/I0 conversion barrier, Li+ intercalation into VS2 reinforces interaction with I3− 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 I3− appearance, and promotion of I3− consumption due to the Li+ insertion. The findings provide fundamental insights into tackling issues of static zinc–iodine batteries.