MXenes-Based Composites for Pseudocapacitors

MXenes, a family of two-dimensional (2D) transition metal carbides/nitrides with a general formula of Mn+1XnTx (n = 1–3), are demonstrated to act as a suitable electrode for high-performance energy storage devices owing to 2D lamellar structure, impressive density, metallic-like conductivity, availability of abundant active edge sites and tunable electrochemical properties, especially in supercapacitors. Nevertheless, MXenes have some demerits due to the aggregation and restacking of nanosheets, which hinder their further exploration. MXenes with the unique 2D layered surface and rich surface functional groups are easy to combine with other functional materials (transition metal oxides, transition metal disulfide compounds, conductive polymers, etc.) to construct composites, which can prevent MXenes aggregation, thereby promoting the formation of stable dispersions. Furthermore, owing to synergistic effects, the electrochemical performance of MXenes-based composites is superior to that of two precursors. In this chapter, the latest research progress of MXenes-based composites is elaborated and discussed. This chapter reviews various methods for preparing MXenes-based composites, introduces their applications in supercapacitors, and analyzes their excellent electrochemical properties. Similarly, we mainly focus on the current development, challenges, and prospects of MXenes-based composites for pseudocapacitors application.