Role of the Electrolyte Concentration in Polysulfide Shuttle and Electrochemical Performance of Lithium–Sulfur Batteries

High Resolution Image Download MS PowerPoint Slide Lithium–sulfur (Li–S) batteries promise high energy density, yet their operation is constrained by a complex interplay of electrolyte, electrode, and interfacial processes. The electrolyte governs dissolution, redox kinetics, and ionic transport, serving as both the enabler and the bottleneck of cell performance. In this work, we develop a microstructure-coupled mechanistic framework to examine how the electrolyte concentration, volume, and solvation strength jointly regulate charge-carrier availability, ionic mobility, and shuttle reactions. The analysis reveals distinct regimes defined by the competition among dissolution, transport, and conversion processes. The electrolyte-to-sulfur ratio and cathode porosity further modulate this balance, delineating a narrow, conductivity-optimal window where kinetics and transport remain coupled. Solvent solubility shifts this window: weak solvation impedes conversion, whereas excessive solvation accelerates shuttle losses. These insights establish a comprehensive conductivity-based design framework linking electrolyte chemistry, solvent properties, and cathode architecture for achieving high-efficiency and durable liquid Li–S batteries.