Interlayer design based on carbon materials for lithium-sulfur batteries: a review

Lithium-sulfur batteries were extensively investigated during the past two decades for their extremely high theoretical specific energy (2600 W h kg(-1)) and volumetric energy density (2800 W h L-1). However, their industrialization has been restrained due to the insulating nature of sulfur, volume expansion of sulfur cathodes, formation of lithium dendrites, and terrible shuttle effect of soluble lithium polysulfides (Li2Sx, 3 <= x <= 8). Many researchers have been struggling with the design of interlayers having remarkable conductivity and polysulfide-trapping capability so that these persistent drawbacks can be overcome. This review summarizes recently developed Li-S batteries with novel interlayers based on carbon materials, such as graphene, carbon nanotubes, carbon fibers, and nanofibers. The electrochemical properties of Li-S batteries with various interlayers are systematically compared. In particular, the enhancing mechanisms of Li-S batteries after the insertion of these interlayers are highlighted. Existing challenges and future development strategies with regard to high-energy Li-S batteries having carbon interlayers have also been summarized, and a prospective has been provided.