Modulation engineering of 2D MXene-based compounds for metal-ion batteries.

The increasing demand for next generation rechargeable metal-ion batteries (MIBs) has boosted the exploration of high-performance electrode materials. Two-dimensional (2D) transition metal carbides/nitrides (MXenes), the largest family of 2D materials, show extremely competitive potential applications in electrodes due to their excellent electrical conductivity, chemical diversity, and large specific surface area. However, the problems of uncontrollable surface functionalization, interlayer restack and collapse significantly hinder their practical applications. To this end, effective strategies to modify traditional MXenes for targeted electrochemical performance are highly desirable. In this mini review, we briefly summarize the most recent and constructive development in the modulation engineering of 2D MXene-based transition-metal compounds. Firstly, to modify traditional MXenes by intercalating, surface decorating and constructing heterostructures. Secondly, to design novel transition-metal compounds beyond MXenes by precisely controlling the atomic structures, proportions and compositions of constituent elements. Moreover, the critical challenges and perspectives for future research on MXene-based materials are also presented.