Multi-Site High-Entropy Immobilizer for All-Iodine Species Fixation in High-Performance Zinc-Iodine Batteries

Abstract

Zinc-iodine (Zn-I₂) batteries are of great interest thanks to their high energy density, low cost, and inherent safety. However, the dissolution of I⁻ and the generated polyiodides exacerbated by the dissolved I⁻ severely reduces the utilization of the active substance, resulting in poor coulombic efficiency and a drastic decrease in performance. In this regard, chemical immobilization of iodine species with high-entropy material is developed. Benefiting from the remarkable catalytic and anchoring activity of the high-entropy material, accelerated catalytic conversion and chemisorption of polyiodides are realized. Meanwhile, the distribution characteristics of the multi-active adsorption centers on the high-entropy material enable the abundant active sites to anchor the highly soluble and hard-to-mobilize I⁻ in a chemical bonding manner. Such a unique bonding mode allows all iodine species (I₂/I⁻/I₃⁻) to be firmly immobilized on the electrode, which enhances the effectiveness and utilization of rechargeable Zn-I₂ batteries. High-entropy material with the ability to immobilize all species of iodine provides a novel/effective strategy for realizing high-performance Zn-I₂ batteries.