Sulfurized Two‐Dimensional Conductive Metal–Organic Framework as a High‐Performance Cathode Material for Rechargeable Mg Batteries

Abstract Rechargeable Mg batteries are a promising energy storage technology to overcome the limitations inherent to Li ion batteries. A critical challenge in advancing Mg batteries is the lack of suitable cathode materials. In this work, we report a cathode design that incorporates S functionality into two‐dimensional metal‐organic‐frameworks (2D‐MOFs). This new cathode material enables good Mg 2+ storage capacity and outstanding cyclability. It was found that upon the initial Mg 2+ insertion and disinsertion, there is an apparent structural transformation that crumbles the layered 2D framework, leading to amorphization. The resulting material serves as the active material to host Mg 2+ through reduction and/or oxidation of S and, to a limited extent, O. The reversible nature of S and O redox chemistry was confirmed by spectroscopic characterizations and validated by density functional calculations. Importantly, during the Mg 2+ insertion and disinsertion process, the 2D nature of the framework was maintained, which plays a key role in enabling the high reversibility of the MOF cathode.