Single‐Specie Selectivity via Subnanometer Hierarchical Porous Channel Metal‐Organic Gels Toward Ultra‐stable Anodes for Zn Metal Batteries

Abstract

Abstract Gel polymer electrolytes demonstrate substantial potential for aqueous zinc‐ion batteries, yet obtaining exquisite balance between molecular/ion sieving precision enhancement and ion conduction pathway optimization remains a persistent scientific challenge. Here, to assure long‐term stabilized zinc electrodeposition, a polyacrylonitrile (PAN)‐Zn(ClO 4 ) 2 ‐DMF metal‐organic gel (MOG) embedded with hierarchical sub‐nanochannels was strategically designed to facilitate single‐specie selectivity toward Zn 2+ . In accordance with the ion‐sieving transition state theory, the MOG accomplished directional discrimination of DMF solvent and ClO 4 − species via synergistic size exclusion effect and interaction force (dipole–dipole interaction, electrostatic interaction and vdW force), which specifically reduces the sieving activation energy of Zn 2+ . Furthermore, ClO 4 − anions with optimized microstructural dimensions and strong coordination ability have stronger interactions with PAN chain segments and promote the dissociation of Zn 2+ from PAN chain segments, which facilitates a smooth Zn 2+ flux through distinctive ion transport pathways. Besides, the PAN@ClO 4 − complex demonstrates sustainable epitaxial stacking characteristics of crystallographically oriented Zn (002) planes, which promote flat and compact Zn deposition. Consequently, the zinc symmetric battery demonstrates an exceptional cycle life exceeding 7000 h at 0.2 mA cm −2 , with extremely lower overpotential (20 mV). Furthermore, the Zn||I 2 cell maintains a capacity retention rate of 81.7% after 10 000 cycles at 0.5 A g −1 .