Enhancing the electrochemical performance of d-Mo2CTx MXene in lithium-ion batteries and supercapacitors by sulfur decoration

With the development of the energy industry, electrochemical energy storage technology is increasingly involved in developing innovations in the field. The materials of the electrode have a significant influence on the performance of energy storage devices. For this purpose, two-dimensional MXene with excellent electrical conductivity, mechanical strength, and a variety of possible surface-active terminations are attracting much attention. In the present work, S-decorated d-Mo2CTx (d-Mo2CTx--S) is designed. The first-principles calculations reveal that it may possess good energy storage characteristics. Due to the decoration with S, unique morphology and structure are obtained, conferring stability, optimized Li+ storage, improved charge transport, and lithium-ion adsorption capabilities. Compared with d-Mo2CTx, d-Mo2CTx--S exhibits higher discharge capacity (623 mAh g−1 at 1 A g−1) as lithium-ion electrode material and higher specific capacitance (561 F g−1 at 1 A g−1). As a supercapacitor, the material also shows excellent cyclic stability (20,000 charge-discharge cycles). This work may inspire the exploration of other MXene and new surface functionalization methods to improve the performance of MXene as electrode materials for new energy devices.