Capture and Catalytic Conversion of Polysulfides by In Situ Built TiO2-MXene Heterostructures for Lithium-Sulfur Batteries

The detrimental shuttle effect in lithium-sulfur batteries mainly results from the mobility of soluble polysulfide intermediates and their sluggish conversion kinetics. Herein, presented is a multifunctional catalyst with the merits of strong polysulfides adsorption ability, superior polysulfides conversion activity, high specific surface area, and electron conductivity by in situ crafting of the TiO2-MXene (Ti3C2Tx) heterostructures. The uniformly distributed TiO2 on MXene sheets act as capturing centers to immobilize polysulfides, the hetero-interface ensures rapid diffusion of anchored polysulfides from TiO2 to MXene, and the oxygen-terminated MXene surface is endowed with high catalytic activity toward polysulfide conversion. The improved lithium-sulfur batteries deliver 800 mAh g(-1) at 2 C and an ultralow capacity decay of 0.028% per cycle over 1000 cycles at 2 C. Even with a high sulfur loading of 5.1 mg cm(-2), the capacity retention of 93% after 200 cycles is still maintained. This work sheds new insights into the design of high-performance catalysts with manipulated chemical components and tailored surface chemistry to regulate polysulfides in Li-S batteries.