MXene/ZIF-67-Based Janus Separator for High-Performance Lithium-Sulphur Batteries

Lithium-sulphur (Li-S) batteries, renowned for their exceptional theoretical energy density, have emerged as promising candidates for next-generation energy storage systems. However, their widespread commercialization remains hindered by the polysulfide shuttle effect and the instability of the lithium (Li) metal anode. In this study, a Janus separator based on ZIF-67 and MXene was proposed to improve the performance of both the cathode and anode. The cathode-facing layer employs a ZIF-67 featuring micropores that selectively confine polysulfides through combined physical sieving and chemical adsorption, effectively suppressing shuttle phenomena. Simultaneously, the anode-oriented MXene layer enhances lithium-ion (Li⁺) diffusion capability through its polar surface functional groups, elevates the Li⁺ transference number, promotes uniform lithium deposition, and effectively suppresses lithium dendrite growth. The Janus separator enables Li-S batteries to achieve exceptional long-term cycling stability under high current density with low capacity decay rate, while maintaining superior discharge capacity even under high sulphur loading conditions. By offering bidirectional functionalization, this design simultaneously stabilizes the sulphur cathode and Li metal anode, providing a novel strategy for advanced separator engineering in Li-S batteries.