Emerging two-dimensional Mo-based materials for rechargeable metal-ion batteries: Advances and perspectives

With the rapid development of rechargeable metal-ion batteries (MIBs) with safety, stability and high energy density, significant efforts have been devoted to exploring high-performance electrode materials. In recent years, two-dimensional (2D) molybdenum-based (Mo-based) materials have drawn considerable attention due to their exceptional characteristics, including low cost, unique crystal structure, high theoretical capacity and controllable chemical compositions. However, like other transition metal compounds, Mo-based materials are facing thorny challenges to overcome, such as slow electron/ion transfer kinetics and substantial volume changes during the charge and discharge processes. In this review, we summarize the recent progress in developing emerging 2D Mo-based electrode materials for MIBs, encompassing oxides, sulfides, selenides, carbides. After introducing the crystal structure and common synthesis methods, this review sheds light on the charge storage mechanism of several 2D Mo-based materials by various advanced characterization techniques. The latest achievements in utilizing 2D Mo-based materials as electrode materials for various MIBs (including lithium-ion batteries (LIBs), sodium-ion batteries (SIBs) and zinc-ion batteries (ZIBs)) are discussed in detail. Afterwards, the modulation strategies for enhancing the electrochemical performance of 2D Mo-based materials are highlighted, focusing on heteroatom doping, vacancies creation, composite coupling engineering and nanostructure design. Finally, we present the existing challenges and future research directions for 2D Mo-based materials to realize high-performance energy storage systems.