A decade of development in cathode-facing surface modified separators for high-performance Li-S batteries

Lithium-sulfur (Li-S) batteries are a promising alternative to conventional lithium-ion batteries (LIBs) for next-generation energy storage. Despite the considerable progress in LIBs, their specific energy density and capacity are nearing theoretical limits, necessitating the exploration of new materials for anodes and cathodes. Li-S batteries, recognized for their high theoretical specific capacity and energy density, have gained extensive attention due to the abundance and energy potential of sulfur. However, their commercialization faces significant challenges, including the insulating nature of sulfur, volume expansion, polysulfide shuttle effects, and dendrite formation at the anode. Recent efforts to address these issues have focused on four main strategies: cathode modification, anode protection, separator modification, and novel electrolyte development. This review emphasizes the role of separator modification in Li-S batteries, a concept introduced to improve cyclic performance and rate capabilities by inhibiting the polysulfide shuttle. This review deals with the development of separator modification with various material compositions reported in the last decade for high-performance Li-S batteries. The review provides a detailed discussion and analysis of cathode-facing surface modified separators based on carbonaceous materials and their composites with inorganic, polymers; and natural clay materials; and their contributions to solving the severe issues in Li-S batteries. This review contributes to the ongoing discourse on improving energy storage devices, mainly focusing on Li-S battery technology and its potential to meet the demands of high energy storage applications.