Recent advances and challenges in 2D metal-covalent organic frameworks toward batteries and supercapacitors

Two-dimensional (2D) metal-containing covalent frameworks (MCOFs), which merge the characteristics of covalent organic frameworks (COFs) and metal-organic frameworks (MOFs), offer remarkable stability, tunable porosity, and catalytic functionalities derived from metal centers through the synergistic interplay between metal nodes and covalent networks. These frameworks have emerged as promising candidates for electrode materials, as metal ions act as molecular modulators, creating a variety of active sites and altering local charge distribution by selecting different metal ions, thereby endowing MCOFs with distinctive energy storage capabilities. Moreover, careful control of synthetic protocols allows precise modulation of their dimensionality and topology, which enhances structural robustness. In the context of energy storage, MCOFs overcome inherent limitations of conventional COFs by leveraging atomic-level engineering of metal sites and innovative dynamic covalent linkages, resulting in improved performance across lithium-ion, lithium–sulfur, and other next-generation batteries. This review provides an overview of recent progress in MCOFs-based high-performance energy storage systems, highlighting their application in batteries and supercapacitors. Additionally, it critically discusses synthesis approaches, structural tuning strategies, and intrinsic framework properties to tackle challenges in diverse energy storage technologies.