Tailoring surface chemistry of MXene/Cationic dye hybrids for enhancing electrocatalytic adsorption and conversion of polysulfide in lithium sulfur batteries

Abstract

The development of host materials for lithium-sulfur batteries (LSBs) necessitates effective sulfur utilization, high energy density, and stable long-term cyclability. Herein, we investigate MXene/cationic dye hybrids prepared through a facile hydrothermal process. As a cationic dye, ethyl violet (EV) induces strong electrostatic interaction with negatively charged MXene surface, resulting in the preservation of intrinsic properties of the MXene nanosheets and favorable surface chemistry engineering to achieve LSBs with high energy density. During the hydrothermal process, the development of crumpled morphologies and partial transformation of Ti in MXene to TiO2 in MXene/EV hybrids (MXEV) provide additional active sites, leading to the efficient electrocatalytic confinement of lithium polysulfides (LiPSs) and their fast conversion. Simultaneously, the incorporation of Nfunctional groups in MXEV microstructures further boosts the electrochemical redox kinetics of LiPSs, resulting in the improvement of LSBs performance. This work provides an effective strategy for rationally modulating the surface chemistry of electrocatalytic materials for high-performance LSBs.