Recent advances in interlayer and separator engineering for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have great potential in next-generation energy storage due to its high theoretical specific capacity and energy density. However, there are several challenges to the practical application of Li-S batteries including the growth of lithium dendrites and the shuttle effect of polysulfide. Introducing interlayeres (freestanding or coated on the separator) is an effective approach to reduce these obstacles and improve the electrochemical performance of Li-S batteries. In this review, we briefly summarize the interlayer materials and structures modified on both cathodic and anodic sides including (i) carbon-based materials, (ii) polymers, (iii) inorganic metal compounds, (iv) metal–organic frameworks, as well as (v) the novel separators in recent years. We also systematically address the fabrication processes, assembling methods, and functions of interlayers for enhancing the performance of Li-S batteries. Furthermore, the prospects and outlooks of the future development of advanced interlayers and separators are also presented.