Recent Advances of Flexible MXene and its Composites for Supercapacitors

MXenes have unique properties such as high electrical conductivity, excellent mechanical properties, rich surface chemistry, and convenient processability. These characteristics make them ideal for producing flexible materials with tunable microstructures. This paper reviews the laboratory research progress of flexible MXene and its composite materials for supercapacitors. And introduces the general synthesis method of MXene, as well as the preparation and properties of flexible MXene. By analyzing the current research status, the electrochemical reaction mechanism of MXene was explained from the perspectives of electrolyte and surface terminating groups. This review particularly emphasizes the composite methods of freestanding flexible MXene composite materials. The review points out that the biggest problem with flexible MXene electrodes is severe self-stacking, which reduces the number of chemically active sites, weakens ion accessibility, and ultimately lowers electrochemical performance. Therefore, it is necessary to composite MXene with other electrode materials and design a good microstructure. This review affirms the enormous potential of flexible MXene and its composite materials in the field of supercapacitors. In addition, the challenges and possible improvements faced by MXene based materials in practical applications were also discussed.