Engineering Ti3C2 Nanosheets with Mesopores and Unsaturated Edges for Synergistic Adsorption-Catalysis of Lithium Polysulfides

Lithium–sulfur batteries are the most promising next-generation batteries but still need to address some issues such as the shuttle effect and sluggish kinetics of polysulfides. Utilizing the strong interaction between two-dimensional (2D) host materials and lithium polysulfides is one of the effective methods to suppress the shuttle effects and accelerate the reaction kinetics. In this work, 2D Ti₃C₂ MXene nanosheets are etched in ammonia–water to produce abundant edge sites for the adsorption and catalytic conversion of lithium polysulfides. Meanwhile, a three-dimensional (3D) network structure is constructed by combining Ti₃C₂ nanosheets with cross-linked carbon nanotubes (CNTs) to accommodate sulfur and facilitate the transport of lithium ions and electron. The experimental test results and theoretical calculations reveal that the edge unsaturated Ti sites of Ti₃C₂ have much higher adsorption energy of lithium polysulfides and lower decomposition energy of Li₂S. Attributing to these structural advantages, the sulfur loaded sample exhibits superior rate performance and prolonged cycle life. This study provides an effective way for the edge engineering construction of 2D materials and their application in the energy field.