Porosity Engineering of MXene Membrane towards Polysulfide Inhibition and Fast Lithium Ion Transportation for Lithium–Sulfur Batteries

Detrimental lithium polysulfide (LiPS) shuttle effects and sluggish electrochemical conversion kinetics in lithium‐sulfur (Li‐S) batteries severely hinder their practical application. Separator modification has been extensively investigated as an effective strategy to address above issues. Nevertheless, in the case of functional separators, how to effectively block the LiPSs from diffusion while enabling the rapid Li ion transport remains a challenge. Herein, by using an “oxidation‐etching” method, MXene membranes are presented with controllable in‐plane pores as interlayer to regulate Li ion transportation and LiPS immobilization. Porous MXene membranes with optimized pore density and size can simultaneously anchor LiPS and ensure fast Li ion diffusion. Consequently, even with pure sulfur cathode, the improved Li–S batteries deliver excellent rate performance up to 2 C with a reversible capacity of 677.6 mAh g−1 and long‐term cyclability over 500 cycles at 1 C with a low capacity decay of 0.07% per cycle. This work sheds new insights into the design of high‐performance interlayers with manipulated nanochannels and tailored surface chemistry to regulate LiPSs trapping and Li ion diffusion in Li–S batteries. 2D MXene shows great potentials in Li–S batteries. A novel strategy is applied to design porous MXene membranes with tunable pore size as the interlayer for Li–S batteries. The MXene membrane composed of optimized porous and conductive MXene nanosheets not only enables effective LiPS anchoring, but also allows for fast Li ion transportation.