Vehicle-type ion transport and shuttle suppression enabled by a Zn2+-centered dual-ligand coordination hydrogel electrolyte toward highly reversible Zn-I2 batteries.

The practical deployment of aqueous Zn-I2 batteries (AZIBs) is severely constrained by two tightly coupled issues: uncontrollable zinc dendrite growth and the shuttling of soluble polyiodides. To address this dual challenge, we engineer a multifunctional polymer hydrogel (PHE) electrolyte by integrating pyrrolidone carboxylate zinc (PCA) into a sulfonate-rich poly-(2-acrylamido-2-methylpropane sulfonic acid) (AMPS) network. This design forms a stable dual-ligand coordination complex, where carboxylate (-COO-) and sulfonate (-SO3 -) groups synergistically chelate Zn2+ ions, establishing a robust three-dimensional ion-conducting matrix. This architecture not only guides uniform Zn deposition by regulating Zn2+ solvation but also reconstructs the hydrogen-bonding network in the bulk, slowing proton mobility via a high-barrier vehicle-type mechanism. Meanwhile, Zn2+-centered electropositive domains strongly interact with polyiodide species (e.g., I3 -), effectively immobilizing them and mitigating shuttle-induced corrosion. Together, this coordination-driven synergy enables concurrent regulation of Zn2+ transport, proton activity, and polyiodide capture within a single electrolyte system. As a result, the PHE endows Zn‖Zn symmetric cells with exceptional dendrite-free cycling stability over 2300 hours, enables a remarkably high coulombic efficiency of over 99.8% in Zn‖Cu asymmetric cells, and empowers Zn-I2 full cells with outstanding longevity, exhibiting an ultralow capacity decay rate of 0.0018% per cycle over 10 000 cycles.