Optimization on transport of charge carriers in cathode of sulfide electrolyte-based solid-state lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are considered as promising candidates for novel energy storage technology that achieves energy density of 500 Wh·kg⁻¹. However, poor cycle stability resulting from notorious shuttle effect and the safety concerns deriving from flammability of ether-based electrolyte hinder the practical application of Li-S batteries. Because of low solubility to polysulfide, high ionic conductivity, and safety property, sulfide-based electrolytes can fundamentally address above issues. It is widely known that the effective transports of both electrons and ions are basic requirement for redox reaction of active materials in cathode. Thereby, construction of fast and stable ionic and electronic transport paths in cathode is especially pivotal for cycle stability of solid-state Li-S batteries (SSLSBs). In this review, we provide research progresses on facilitating transport of charge carriers in composite cathode of SSLSBs. From perspective of materials, intrinsically conductivity of electrolyte and carbon shows dramatic effect on migration of charge carriers in cathode of SSLSBs, thereby the conductive additives are summarized in the manuscript. Additionally, the charge transport in cathode of SSLSBs fully depends on the physical contact between active materials and conductive additives, therefore we summarized the strategies optimizing interfacial contact and reducing interfacial resistance. Finally, potential future research directions and prospects for SSLSBs with improved energy density and cycle performance are also proposed.