Topological Crosslinker Design Regulates Interfacial and Active Species Transport in Zinc-Iodine Batteries.

Abstract

Aqueous zinc-ion batteries (ZIBs) are limited by interfacial instability and an intrinsic trade-off between mechanical strength and ionic conductivity in polymer gel electrolytes (PGEs), restricting their cycling durability and practical application. Here, we report a topology-regulated crosslinker strategy that redefines crosslinkers from passive structural components to active regulators of ion transport and interfacial chemistry. A tetra-armed poly(2-ethyl-2-oxazoline) (4-PEtOx) crosslinker is integrated into a zwitterionic network to construct a hydrogel electrolyte (4-PVEX). The unique molecular topology establishes a dense yet dynamic hydrogen-bonding framework, enabling continuous Zn²⁺ transport pathways while maintaining high mechanical strength. As a result, 4-PVEX stabilizes the Zn/electrolyte interface, promotes uniform dendrite-free Zn deposition, suppresses parasitic reactions, and effectively immobilizes polyiodide species while accelerating iodine redox kinetics. Zn||Zn symmetric cell exhibits stable cycling for over 2700 h, and Zn||Cu cell delivers an average Coulombic efficiency of 99.7% over 1000 cycles. Moreover, Zn||I₂ full cell retains 90% of its initial capacity after 10 000 cycles at 10 C. This work demonstrates molecular topology as a powerful design dimension for advanced gel electrolytes and provides new insights into interfacial and transport regulation in aqueous metal batteries.