Optimizing Porous Metal-Organic Layers for Stable Zinc Anodes

Aqueous zinc-ion batteries (ZIBs) have been considered as alternative stationary energy storage systems, but the dendrite and corrosion issues of Zn anodes hinder their practical applications. Here we report a series of two-dimensional (2D) metal-organic frameworks (MOFs) with Zr₁₂ clusters, which act as artificial solid electrolyte interphase (SEI) layers to prevent dendrites and corrosion of Zn anodes. The Zr₁₂-based 2D MOF layers were formed by incubating 3D layer-pillared Zr-MOFs in ZnSO₄ aqueous electrolytes, which replaced the pillar ligands with terminal SO4^2-. Furthermore, the pore sizes of Zr₁₂-based 2D MOF layers were systematically tuned, leading to optimized Zn²⁺ conduction properties and protective performance for Zn anodes. In contrast to the traditional 2D-MOFs with Zr₆ clusters, Zr₁₂-based 2D MOF layers as artificial SEI significantly reduced the polarization and increased the stability of Zn anodes in MOF@Zn||MOF@Zn symmetric cells and MOF@Zn||MnO₂ full cells. In situ experiments and DFT computations reveal that the enhanced cell performance is attributed to the unique Zr₁₂-based layered structure with intrinsic pores to allow fast Zn²⁺ diffusion, surface Zr-SO₄ zincophilic sites to induce uniform Zn deposition, and inhibited hydrogen evolution by 2D MOF Zr₁₂ layers.