MOF‐74 as a Platform for Metal Node‐Guided Chloride Storage Mechanisms in Anion‐Based Batteries

Abstract Metal–organic frameworks (MOFs) remain scarcely explored as cathodes in chloride‐ion batteries (CIBs), an emerging technology featuring high volumetric energy density, dendrite‐free operation, and reliance on earth‐abundant chlorine. Their tunable channels, high porosity, and open metal sites offer unique opportunities for anion storage, yet the role of metal‐node identity in governing storage mechanisms is unclear. Herein, a series of isostructural M‐MOF‐74 (M = Mg, Mn, Co, Ni, Cu, and Zn) is employed as model cathodes to unravel the metal nodes‐function relationships of Cl − storage. Combined electrochemical and theoretical analyses reveal two distinct mechanisms: Zn‐MOF‐74 stores Cl − via reversible adsorption within 1D channels, stabilized by its filled 3d 10 configuration, whereas Co‐ and Ni‐MOF‐74 rely on Faradaic redox reactions. In contrast, Mg‐, Mn‐, and Cu‐MOF‐74 undergo severe distortions, leading to structural degradation and poor reversibility. Zn‐ and Co‐MOF‐74 exhibit the most promising electrochemical performance, retaining 159.2 and 144.8 mAh g −1 after 250 cycles with near‐unity coulombic efficiency. DFT calculations underscore the critical role of metal electronic configuration in modulating Cl − affinity, charge distribution, and migration barriers. These findings demonstrate that the intrinsic electronic configuration of metal centers dictates Cl − affinity and migration, establishing metal‐node engineering as a powerful strategy to advance anion‐based battery technologies.