Molecularly engineered dual-network eutectogel electrolytes for high-loading and stable zinc-iodine batteries

Abstract

Aqueous zinc-iodine batteries (AZIBs) are attractive for safe and low-cost energy storage, yet their practical deployment is hindered by the instability of both Zn anodes and iodine cathodes, particularly under high iodine loading and wide-temperature conditions. Herein, we report a molecularly engineered dual-network eutectogel electrolyte that enables simultaneous regulation of Zn deposition and polyiodide chemistry. The electrolyte is constructed by in situ polymerization of poly(N-hydroxyethyl acrylamide) (PHEAA) and poly([3-(methacrylamido)propyl]dimethyl(3-sulfopropyl)ammonium) (PDMAPS) within a choline chloride/glycerol deep eutectic solvent. In this design, PHEAA preserves structural integrity and stable interfacial contact, while PDMAPS provides spatially distributed -SO3− /-NR4+ sites for Zn2+-flux homogenization and polyiodide immobilization. Coupled with the DES-regulated hydrogen-bonding and solvation environment, the resulting dual-network eutectogel electrolyte simultaneously stabilizes Zn deposition and iodine redox chemistry under high-loading conditions. Meanwhile, the eutectic hydrogen-bonding environment and dense dual-network framework provide high ionic conductivity, structural robustness, and wide-temperature adaptability. As a result, the resulting AZIBs deliver long-term cyclability over 35,000 cycles, stable operation from −40 to 60 ℃, and durable cycling over 1000 cycles at an iodine loading of 19 mg cm−2, together with promising pouch-cell performance. This work establishes a dual-regulation electrolyte-engineering strategy for high-loading and stable AZIBs.