Electrochemistry and speciation of sulfur/polysulfides in ionic liquid-based lithium sulfur batteries

Lithium-sulfur batteries have the prospect of replacing current lithium-ion batteries due to their higher energy storage capability and reduced environmental impact. The solubility of discharge products, polysulfides, and the associated side effects on the performance are influenced by the electrolyte of the battery. The stability and transport properties of these polysulfide ions were investigated in room temperature molten salts or ionic liquids electrolyte. It was observed that the stability of the polysulfide intermediates and recovery of sulfur during the charging cycle was greatly improved compared to the commonly used organic electrolytes, which lead to better capacity retention during battery cycling.