Reprogramming Ion-Transport Dimensionality via Crystal-Channel Engineering to Stabilize Zinc Anodes.

Unstable zinc (Zn) deposition in aqueous zinc-ion batteries is intrinsically linked to the interfacial confinement of Zn2+ transport, where ion migration is dominated by lateral diffusion along the electrode surface. This quasi-two-dimensional transport amplifies local electric-field and concentration heterogeneities, leading to uneven nucleation and dendritic growth. Here, we demonstrate that Zn deposition can be fundamentally regulated by reprogramming the dimensionality of ion transport. A three-dimensionally interpenetrated covalent organic framework (COF) incorporating crown-ether moieties is embedded into a hydrogel electrolyte. The confined macrocyclic sites selectively coordinate Zn2+ and partially displace solvating water molecules, while the interconnected crystalline channels enable continuous, isotropic bulk ion migration. This architecture converts Zn2+ transport from interface-limited diffusion to bulk-governed three-dimensional flux, resulting in intrinsically uniform Zn deposition. Consequently, symmetric Zn cells exhibit stable cycling for over 2000 h at 1 mA cm-2, and Zn||NH4V4O10 full cells retain 81.6% of their capacity after 3000 cycles. These findings identify ion-transport dimensionality as a key descriptor for metal-deposition stability and establish a general electrolyte-engineering strategy that transcends conventional regulation.