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 Zn 2+ 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 Zn 2+ and partially displace solvating water molecules, while the interconnected crystalline channels enable continuous, isotropic bulk ion migration. This architecture converts Zn 2+ 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||NH 4 V 4 O 10 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.