A High-Metal-Content 2D Conjugated Metal-Organic Framework With a Bis-Salphen Architecture for Dendrite-Free Sodium...

Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) are promising candidates for electrochemical applications. However, their performance is frequently constrained by conventional designs that utilize large planar conjugated ligands. Such architectures not only complicate synthetic routes but also inherently restrict the density of metal nodes, thereby limiting the availability of ion-binding sites and impairing their efficacy in interfacial regulation. To address these challenges, we present a ligand design strategy based on a non-planar bis-Salphen ligand, which incorporates multiple inner N₂O₂ coordination pockets and peripheral catechol groups. Coordination with Zn²⁺ ions yields a new 2D Zn-BSP-MOF, wherein the ligand undergoes in situ Scholl cyclodehydrogenation during synthesis, resulting in a fully conjugated planar structure. When employed as an artificial interlayer for sodium-less metal anodes, Zn-BSP-MOF exploits its high density of uniform metal-based binding sites to guide homogeneous sodium nucleation and suppress dendrite growth. Notably, symmetric cells demonstrate outstanding stability, operating for over 1800 h at 0.05 mA cm^-2 and over 800 h at 0.1 mA cm^-2. Full cells paired with a Na₃V₂(PO₄)₃ cathode deliver a high reversible capacity of 104.8 mAh g^-1 after 400 cycles at 1 C, with 96.8% capacity retention.