Recent advances in multiple transition metal MXenes: Synthesis, properties, and applications in energy storage

Abstract

MXenes, a family of two-dimensional transition metal carbides, nitrides, and carbonitrides, are particularly favored in the energy storage field due to their exceptional electronical conductivity, diverse surface terminations, tunable compositions, excellent hydrophilicity, and ease of processing. As a new intriguing type of MXenes, multiple transition metal (MTM) MXenes comprising double transition metal, medium-entropy, and high-entropy MXene, have garnered significant attention since the first synthesis of Mo2TiC2Tx and Mo2Ti2C3Tx in 2015. This review comprehensively covers recent advancements in MTM MXenes and their composites, focusing on their categories, properties, synthesis and potential applications in energy storage. A detailed comparison of various MTM MXene synthesis methods is presented, highlighting their critical impacts on structure, surface functional groups and properties. Furthermore, the applications of MTM MXenes in supercapacitors, lithium-ion batteries, sodium-ion batteries, magnesium-ion batteries, zinc-ion batteries, and other rechargeable batteries system are thoroughly discussed. Finally, the challenges and future prospects of MTM MXenes are addressed to support their sustainable development in energy storage applications.