Bio‐Inspired Helical Host‐Guest Hydrogel Electrolytes for Reversible Polyiodide Regulation in Flexible Aqueous Zn||I 2 Batteries

ABSTRACT Aqueous Zn||I 2 batteries are promising candidates for safe and flexible energy‐storage systems, yet their practical application is hindered by polyiodide shuttling, self‐discharge, and unstable Zn deposition. Herein, inspired by the classical starch‐iodine complexation phenomenon, a bio‐inspired PVA/AP double‐network hydrogel electrolyte is developed by integrating amylopectin (AP) helical host sites within a poly(vinyl alcohol) (PVA) supporting framework. Unlike conventional confinement strategies based on physical blocking or nonspecific adsorption, the AP‐derived helical domains enable reversible host‐guest interactions with polyiodides, thereby regulating polyiodide chemistry while preserving iodine‐redox reversibility. Meanwhile, the PVA framework provides structural support and continuous Zn 2+ ‐transport pathways, enabling the effective utilization of AP within a self‐supporting hydrogel network. Experimental and theoretical investigations reveal that the AP‐derived helical environment reversibly confines polyiodides while promoting homogeneous Zn deposition. Consequently, the hydrogel electrolyte enables stable Zn plating/stripping for 2100 h and excellent resistance to self‐discharge with 98.1% capacity retention after 48 h resting. The corresponding Zn||I 2 battery exhibits durable cycling over 5000 cycles with 80.1% capacity retention while maintaining reliable operation under flexible and abuse conditions. This work translates starch‐iodine complexation into a hydrogel‐electrolyte design principle and establishes a biomolecular host‐guest strategy for regulating polyiodide chemistry in flexible aqueous Zn||I 2 batteries.