Research Progress on the Modification of Separators for Li-S Batteries

Lithium–sulfur batteries have become one of the research focuses of scientists over the past decade due to their high theoretical specific capacity (approximately 1670 mAh/g), low cost, and environmental friendliness, and the abundant reserves of their raw materials. Nevertheless, they still suffer from inherent drawbacks including poor electrical conductivity of elemental sulfur, electrode volume expansion during charge–discharge cycles, the shuttle effect and lithium dendrite growth, which severely restrict their practical application and industrialization. To address the above issues, extensive research has been carried out to optimize cathode materials, separators and electrolytes. In particular, the shuttle effect occurring during cycling can be effectively mitigated via separator modification. This paper briefly introduces the design strategies for separators for lithium–sulfur batteries, and mainly summarizes separator-modification methods using carbon materials, graphene, carbon nanotubes, heteroatoms, polymers, metal–organic frameworks (MOFs) and covalent organic frameworks (COFs). Finally, the future development trends of lithium–sulfur batteries are prospected.