MXenes as conductive and mechanical additives in energy storage devices

Two-dimensional (2D) transition metal carbides and/or nitrides, known as MXenes, are promising building blocks in energy storage devices and other applications. In particular, the 2D morphology, high aspect ratio coupled with the metallic conductivity and distinguished Youngs modulus open up intriguing opportunities for MXenes to assemble electrodes, decorate electrolyte or separator with enhanced stability and performances. Understanding the correlations between these physical properties of MXenes and the required functions in supercapacitor and batteries are of great importance. In this review, we discuss the critical roles of MXene components in the electrode architecture, particularly through the viewpoints of conductive electrode host and mechanically additive binders to enhance the electron transfer and structural stability. MXenes as mechanical reinforcement phases in electrolyte and separator materials are also highlighted. Finally, we conclude the challenges and future perspectives of MXenes in advanced energy storage applications.