Screening Conductive Mxenes for Polysulfide Adsorption in Li-S Batteries

Lithium-sulfur batteries (LSBs) show promise as next-generation batteries due to their high charge density and natural abundance of sulfur. Nevertheless, their commercialization faces challenges due to the polysulfide shuttle effect and the insulating nature of sulfur and discharge products. MXenes have recently emerged as a solution by providing conducting pathways and polar sites to trap lithium polysulfides (LiPSs). While previous studies have explored the potential of MXenes in various passive components, a quantitative investigation of polysulfides adsorbed on MXenes, a crucial factor in enhancing LSB performance, remains lacking. In this study, we systematically investigate LiPSs adsorbed on seven MXenes: Ti 2 CT x , Ti 3 C 2 T x , Ti 3 CN x , Mo 2 TiC 2 T x , V 2 CT x , Nb 2 CT x , and Nb 4 C 3 T x . We explore the influence of soaking time, polysulfide concentration, and MXene composition on polysulfide adsorbed. Our spectroscopic findings reveal the formation of thiosulfate and polythionate species upon polysulfide adsorption for all MXene compositions. Furthermore, our study reveals the specific preferences of sulfur and lithium adsorbed on the MXene surface, dependent on MXene chemistry, adding a new level of understanding to the field. We expect our work can serve as a general guiding principle for the rational selection of MXenes for various passive components in the development of high-performance LSBs.