Regulating Reversible Zn Deposition via a 2D Metal-Organic Framework-Laden Hydrogel Electrolyte

The practical deployment of aqueous Zn-ion batteries (AZIBs) is impeded by dendritic growth and parasitic side reactions of Zn anodes, which severely compromise reversibility and cycle stability. Herein, a hydrogel electrolyte (HE) is reported integrated with a 2D porphyrin-based metal-organic framework (MOF) as a multifunctional filler to address these issues. The incorporation of the 2D MOF not only reinforces the mechanical integrity and enhances the ionic conductivity (14.87 mS cm^-1) of the hydrogel matrix, but also serves a critical interfacial role. During cycling, the MOF nanosheets spontaneously adsorb at the Zn-electrolyte interface, where porphyrin ligands with four nitrogen donor sites effectively capture Zn²⁺ ions to facilitate a uniform Zn nucleation. Moreover, the MOF-derived interphase suppresses dendrite formation and mitigates interfacial side reactions, thereby significantly improving the reversibility and durability of Zn anodes. As a result, the MOF-laden HE enables Zn anodes with a high average Coulombic efficiency of 98.8% in the first 20 cycles, prolonged plating/stripping stability over 3000 h, and a high critical current density of 12 mA cm^-2. Furthermore, full cells coupled with a vanadium-based cathode exhibit excellent cycling performance, achieving 78% capacity retention over 2000 cycles at 1 A g^-1.