Pyrazine-Linked 2D Covalent Organic Frameworks as Coating Material for High-Nickel Layered Oxide Cathodes in Lithium-Ion Batteries

and low dependence on cobalt have enhanced the research interest on nickel-rich layered metal oxides as cathode materials for lithium-ion batteries for electric vehicles. Nonetheless, their poor cycle life and thermal stability, resulting from the occurrence of cation mixing between the transition-metal (TM) and lithium ions, are yet to be fully addressed to enable the widespread and reliable use of these materials. Here, we report a two-dimensional (2D) pyrazine-linked covalent organic framework (namely, Pyr-2D) as a coating material for nickel-rich layered cathodes to mitigate unwanted TM dissolution and interfacial reactions. The Pyr-2D coating layer, especially the 2D planar morphology and conjugated atomic configuration of Pyr-2D, protects the electrode surface effectively during cycling without sacrificing the electric conductivity of the host material. As a result, Pyr-2D-coated n…