Configurational and structural design of separators toward shuttling-free and dendrite-free lithium-sulfur batteries: A review

Lithium-sulfur batteries (LSBs) are attracting increasing interest due to their advantages in high energy density, low cost and eco-friendliness. However, the shuttle effect of polysulfides and the uncontrollable growth of lithium (Li) dendrites, derived from the intrinsic characteristics of sulfur (S) cathode and Li anode, significantly deteriorate the electrochemical performance and threaten the safety of LSBs. The separator plays a profound role in the mass transport across the interfaces against both S cathode and Li anode; thus, separator engineering is the most promising and effective method to simultaneously tackle shuttle effect and dendrite growth. Fruitful work has reported the design and fabrication of functional separators that enable safe, durable, shuttling-free and dendrite-free LSBs. This review summarizes recent progress on dual-functional separators based on their configurations, i.e., sandwiched configuration, Janus configuration and composite configuration. The material selection, structure and function design, manufacturing techniques of each separator configurations have been emphasized in this review. The perspectives and challenges of advanced separators for their large-scale application in high-performance LSBs are discussed to provide guideline for the future development.