A high-throughput screening permeability separator with high catalytic conversion kinetics for Li–S batteries

Abstract

The practical application of Li–S batteries is seriously hindered by intricate lithium polysulfide shuttling and sluggish electrochemical conversion kinetics. Separator modification has been demonstrated as an effective strategy to solve these problems. Herein, a hierarchical crumpled MXene/MoS₂ (CM/MoS₂) heterostructure is exploited as an efficient ion-selective membrane on a PP separator to simultaneously realize robust LiPS immobilization, efficient catalytic conversion kinetics, and feasible lithium-ion diffusion. The experimental and theoretical results validate that the MXene/MoS₂ heterostructure not only chemically immobilizes LiPSs through a combination of Lewis acid–base interaction and sulfur-chain catenation, but also catalytically converts LiPSs into Li₂S₂/Li₂S due to a reduced diffusion barrier for Li atoms. Furthermore, the quantitative evaluation of the rejection of LiPSs and performance of electrolyte permeability substantiate the unique high-throughput screening permeability of the CM/MoS₂ coating layer due to the intelligent pore architectures and efficient anchor-catalytic sites. Therefore, the CM/MoS₂-modified separator achieves instantaneous modulation of polysulfide interception/conversion and Li⁺ diffusion. Attributed to these unique merits, Li–S batteries with the CM/MoS₂-modified separator deliver a high capacity of 1336 at 0.1C, a considerable areal capacity of 5.5 mA h cm⁻², an excellent rate capability of 810 mA h g⁻¹ at 2C, and stable cycling performance over 500 cycles at 1C with a low capacity decay of 0.056% for each cycle.