Enabling fast diffusion/conversion kinetics by thiourea-induced wrinkled N, S co-doped functional MXene for lithium-sulfur battery

• The N, S functionalized MXene was synthesized by facile thiourea pyrolysis . • Wrinkled NSMX induces the fast sulfur reduction/evolution reaction and ion diffusion kinetics. • In-situ Raman and DFT calculations indicate that the shuttling of PS is well confined. • The cell with NSMX delivers admirable cyclic stability at high S loading and lean E/S. The long lifespan of high-energy density lithium-sulfur batteries (LSBs) is still hindered by severe polysulfide (PS) shuttling and sluggish sulfur reduction/evolution kinetics process. Herein, we report a facile preparation of thiourea-induced wrinkled nitrogen and sulfur co-doped functionalized MXene (NSMX) to modify the separator to enhance the ion diffusion and conversion kinetics for high-energy LSBs. The combination of theoretical calculations and experimental conclusions demonstrates that the introduction of N, S heteroatoms induces the shift of the d-band center in transition metal Ti towards the Fermi level and results in the robust bonding effect between N/S atoms and Li atom in PS , hence exhibiting admirable adsorption capability to PS and fast catalytic PS reversible conversion rate, which quickly deplete soluble high-order PS and expedites the depletion of the Li 2 S 6 in high potential. The 2D wrinkled polar surface with excellent conductivity assures fast electron transfer and ion migration. Profiting from the enhancement of S utilization and the reduction of unfavorable accumulated Li 2 S 6 , the LSBs equipped with NSMX modified separators exhibit a high specific capacity of 1249 mAh g −1 at 0.2 C. At a high rate of 5 C, the LSBs also delivered an impressive reversible capacity of 600 mAh g −1 . Moreover, a high capacity and stable cycling can be achieved even under the condition of high S load and lean electrolyte consumption. The efficient sulfur species circulation is realized by the wrinkled N, S co-doped MXene which effectively enhances the ion diffusion capability and ensures the robust adsorption-catalytic effect on polysulfide, thereby significantly improving the cyclic stability of lithium-sulfur batteries and relieving the shuttle effects.