A review on MXene—Carbon, polymer, metal oxide and 2D composites for high performance supercapacitor applications

• Summarizes recent advances in MXene based composites for supercapacitor applications. • MXene composites with carbon, metal oxides, polymers, and 2D materials are compared. • Consolidated performance metrics for each composite category were examined. • Covers MXene synthesis methods and their properties. • Examines unresolved issues and suggests directions for future work on MXene supercapacitors. MXenes have emerged as one of the most powerful electrode materials in the family of supercapacitor electrode material due to their high conductivity, tunable surface chemistry, and layered architecture. Many reviews either focus exclusively on pure MXenes or explore only a limited subset of composite architectures, thus leaving a deficit in developing a unified understanding of these materials. This review summarizes systematically the recent advances in MXene/carbon (330–430 F.g -1 , up to 410 mF.cm -2 , 850 F.cm -3 ), MXene/metal oxide(150–950 F.g -1 , 29.46–117.1 Wh.kg -1 , 29.46–117.1 Wh.kg -1 , 86.4–97.2 % - 10,000 stability), MXene/polymer(270–563.8 F.g -1 , 65.6 W.Kg -1 , 4077 Wh.Kg -1 ), MXene/2D (1531.2 F.g -1 , 94.1 %-10,000 cycles) and MXene/biopolymer (286.28 F.g -1 , 98 % cycling stability). The results obtained from these composites reveal their broad capabilities and versatility towards applications in flexible electronics, portable electronics, electric vehicles, and grid-level systems. This review aims at consolidating the understanding and providing a forward-looking direction for designing next-generation MXene based supercapacitors. Furthermore, this review facilitates the rapid identification of relevant research content, elucidates the interconnections among existing studies, and highlights the challenges that must be addressed for the future development of MXene materials.