Sulfur Solubility in Sulfolane Electrolytes Sutable for Lithium-Sulfur Batteries

The solubility of sulfur in sulfolane and solutions of lithium salts [LiBF 4 , LiClO 4 , LiPF 6 , LiSO 3 CF 3 and LiN(SO 2 CF 3 ) 2 ] in sulfolane, which are promising electrolytes for lithium-sulfur batteries, was determined by UV-vis spectroscopy. It was found that the solubility of sulfur in sulfolane at 30°C is 82.0 mM, and in sulfolane solutions of lithium salts (1 M) it is 4–9 times lower. The dependence of sulfur solubility on the concentration of lithium salts is not linear: it is 32.9 and 5.8 mM for sulfolane solutions containing 0.5 and 2.35 M of LiClO 4 , respectively.