Design Strategies, Challenges, and Prospects of Nanomaterials for Aqueous Zn-Iodine Batteries

Aqueous zinc-iodine batteries (AZIBs) are important candidates for energy storage systems because of the low cost, high safety, multiple electron transfer properties, and high theoretical capacity (820 mAh g^-1) of zinc metal. However, the practical application of AZIBs still faces significant challenges, mainly including the slow redox kinetics of iodine and the shuttle effect of polyiodides. The shuttle effect not only reduces the active material at the cathode, but also shuttles to the anode side to undergo a severe self-discharge reaction with the zinc anode, which leads to corrosion of zinc anodes and side reactions such as surface passivation. To inhibit shuttle effect, the main research direction is to find cathode host materials with strong iodine and polyiodide adsorption properties, and therefore this review focuses on studies related to nanomaterials. The purpose of this review is to provide an overview of different energy storage mechanisms and the various challenges AZIBs face. Various strategies for inhibiting the shuttle effect of iodine species are then discussed, including cathode material design, anode protection, and electrolyte regulation. Furthermore, this paper provides an outlook on the future research prospects of nanomaterials in the field of AZIBs. This review aims to offer an updated overview of the current development status of AZIBs and provide valuable guidance for achieving high-performance AZIBs, thereby facilitating their further advancement.