Cation-selective separators for addressing the lithium-sulfur battery challenges.

Lithium-sulfur battery (LSB) has become one of the most promising candidates for next-generation energy storage systems owing to its high theoretical energy density, environmental friendliness， and cost-effectiveness. However, its real-word applications are seriously restricted by its undesirable shuttle effect and lithium (Li) dendrite formation. In essence, uncontrollable anion transport is a key factor that causes both polysulfide shuttling and dendrite formation, which creates the possibility of simultaneously addressing the two critical issues in LSBs. An effective strategy to control anion transport is the construction of cation-selective separators. A significant progress has been achieved in the inhibition of the shuttle effect, whereas addressing the problem of Li dendrite formation by utilizing a cation-selective separator is still underway. From this viewpoint, this review analyzes the critical issues with regard to the shuttle effect and Li dendrite formation caused by uncontrollable anion transport, based on which the roles and advantages of cation-selective separators toward high-performance LSBs are presented. According to the separator construction principle, the latest advances and progress in cation-selective separators in inhibiting the shuttle effect and Li dendrite formation are reviewed in detail. Finally, some challenges and prospects are proposed for the future development of cation-selective separators. This review is anticipated to provide a new perspective for simultaneously addressing the two critical issues in LSBs.