Polar-Nonpolar Synergy Toward High-Performance Aqueous Zinc–Iodine Batteries

Abstract

Aqueous zinc-iodine batteries (AZIBs) hold great promise for large-scale energy storage due to their inherent safety, cost-effectiveness, and environmental sustainability. However, their practical application is hindered by the sluggish redox kinetics of iodine species and the “shuttle effect” of polyiodides, both of which degrade cycling stability and capacity retention. Herein, a “polar-nonpolar strategy” is proposed for the first time, which couples nonpolar porous carbon (PC) as the iodine host with highly polar zinc oxide (ZnO) as separator modification materials. Specifically, the PC host leverages its porous structure and nonpolar properties to accommodate and immobilize iodine, simultaneously enhancing the conductivity of the cathode. Meanwhile, the polar ZnO on the separator accelerates electron transfer with polyiodides through strong adsorption and catalytic effects, improving the reversible transformation of iodine species. UV–visible spectroscopy and electrochemical kinetic analyses confirm the rapid transformation and effective polyiodide inhibition in this system. As a result, the prepared PC-I₂//ZnO@GF battery demonstrates high-rate capacity and excellent long-term cycling stability, surpassing the performance of other recently reported AZIBs. This polar-nonpolar strategy establishes a novel design rationale for developing future high-performance zinc-iodine batteries.