MXene-based ternary composites for supercapacitors: Advancements and challenges

The acceleration of the global energy transition and the achievement of Sustainable Development Goals (SDGs) depend on promoting innovation in energy storage technologies. MXenes and their composites have emerged as novel electrodes for electrochemical energy storage. Numerous investigations into MXene binary nanocomposites have shown that they can deliver enhanced electrochemical performance when compared to their pristine forms. However, strong van der Waals forces between layers in MXene nanosheets can result in restacking, which lowers capacitance and slows kinetics, thereby limiting their practical applications. To achieve an enhanced electrochemical performance, attention has been shifted to MXene-based ternary nanocomposites for supercapacitors. In comparison to the previous binary system, these unique ternary MXenes display newly produced features and high-performance activity. This promotes synergism and results in superior capacitance, charge transfer kinetics, high specific energy and power, and enhanced stability. Nevertheless, based on the review of the literature, not much work has been done to prepare and investigate this novel ternary nanostructure for supercapacitors. Therefore, this review provides insights into recent advances in MXene-based ternary composites with a view to establishing the connection between their properties and supercapacitor performance. The performance of MXene-based ternary composites in supercapacitors and micro-supercapacitors are enumerated, including their practical applications. Finally, challenges and outlooks for further improving the performance of ternary composites in energy storage are highlighted.