Hierarchically Porous TiC MXene with Tunable Active Edges and Unsaturated Coordination Bonds for Superior Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries hold great promise for next-generation electronics owing to their high theoretical energy density, low cost, and eco-friendliness. Nevertheless, the practical implementation of Li-S batteries is hindered by the shuttle effect and sluggish reaction kinetics of polysulfides. Herein, the spray drying and chemical etching strategies are implemented to fabricate hierarchically porous MXene microspheres as a multifunctional sulfur electrocatalyst. The interconnected skeleton offers uniform sulfur distribution and prevents the restacking of MXene sheets, while the abundant edges endow the nanosheet-like TiC with rich active sites and regulated a d-band center of Ti atoms, leading to strong lithium polysulfide (LiPS) adsorption. The unsaturated Ti on edge sites can further act as multifunctional sites for chemically anchoring LiPS and lowering Li-ion migration barriers, accelerating LiPS conversion. Owing to these structural advantages, excellent cycling and rate performances of the sulfur cathode can be obtained, even under a raised sulfur loading and lean electrolyte content.