“Shuttle” in Polysulfide Shuttle: Friend or Foe?

The polysulfide shuttle effect, where sulfur species reach the negative electrode surface and undergo chemical reduction, is believed to be a major bottleneck in lithium–sulfur chemistry. The importance of this phenomenon is often judged based on phenomenological arguments, which do not account for mesoscale complexations. This work presents a comprehensive investigation of the coupled interactions arising from speciation, concentrated electrolyte solution, and reaction time scales. Polysulfide transport consists of diffusion and migration, which determines the net flux. This study demonstrates that the polysulfide shuttle effect can be bounded between reaction-limited and shuttle-limited regimes, depending on the operational extremes. At high sulfur to electrolyte ratio (i.e. lean electrolyte condition), the polysulfide shuttle effect may not necessarily attribute to the cell performance limitation, believed contrarily otherwise.