The use of electrocatalyst to accelerate the sulfur conversion kinetics has the appeal of a promising solution to improve the performance of lithium–sulfur batteries, but remains a great challenge under lean electrolyte conditions due to the preponderance of solid reaction products (sulfur and Li₂S) in a small amount of electrolyte and the difficulty of catalyzing solid sulfur and Li₂S. In this report, we describe the development of a mediated catalytic pathway in which a solid cathode catalyst is used alongside a soluble mediator to enable a cooperative catalysis that increases the sulfur utilization from 44% to 61% for high–loading (5.6 mg_S cm^–2) lean–electrolyte (5.0 µL mg_S^–1) Li–S batteries. The improved sulfur utilization is because the mediator acts as a scavenger being able to capture and reutilize dead sulfur species from the sulfur cathode. This mediator-assisted catalysis concept represents an attractive strategy to improve the performance of lean-electrolyte lithium–sulfur batteries and helps to understand the effect of solid S/Li₂S in the catalysis of polysulfide conversion reactions.

 

redox mediator, mediated catalysis, lean electrolyte, Li‒S batteries