CdS Nanocrystals Grown on MXene Frameworks for Stable Lithium−Sulfur Batteries

Lithium−sulfur (Li−S) batteries have been widely studied in recent years due to their high theoretical specific capacity and high energy density. However, the S cathode is plagued by issues of low electrical conductivity, shuttling of lithium polysulfides (LiPSs), and slow transformation kinetics, resulting in low rate performance and rapid capacity fading of Li−S batteries. Here, CdS nanocrystals with ultrafine size are grown in situ on accordion-like and highly conductive Ti3C2 MXene frameworks by a simple and low-temperature (60 °C) hydrothermal reaction. The loading of CdS nanocrystals on MXene is controlled by regulating the amount of precursors. The functional groups on MXene can act as nucleation sites to promote the uniform growth of CdS nanocrystals among the MXene frameworks. Besides, the accordion-like structure of MXene can restrict the excessive growth of CdS. The fabricated CdS/MXene composite with sufficient adsorption and catalytic active sites can effectively block the shuttle effect and accelerate the transformation of LiPSs, thus relieving the issues of the S cathode. Under the coordinated regulation of MXene frameworks and in situ-grown CdS nanocrystals, Li−S batteries exhibit superior cycling performance and rate capability.