Electrochemical Performance of Lithium-Sulfur Cells in Various Organic Electrolyte Solutions

Lithium-ion batteries (LIB) have been widely used as the power source of portable electronic devices, and their application area have been recently expanded to electric vehicles and large-scale storage system. However, current LIB technologies are faced with severe limitations of cost and energy density. For this reason, a number of researchers are trying to find alternative systems to replace lithium-ion batteries. Lithium-sulfur (Li-S) batteries are considered as one of strong candidates due to high theoretical capacity (1675 mAh/g-sulfur) and low cost of active materials. It has been known that the electrochemical reactions of the sulfur cathode are fairly complicated, which consist of several charge transfer reactions and complex chemical reactions. It is commonly accepted that the physicochemical and electrochemical properties of polysulfides and lithium anodes are critically dependent on the type of organic solvent. In result, electrochemical performance of Li-S cells is strongly affected by electrolyte systems. Up to now, however, a few studies on electrolyte systems for Li-S cells have been presented. In this study, comprehensive studies to find a suitable electrolyte solution are presented. Chemical reactivity and stability of polysulfides and lithium metal in a number of organic solvents are systematically investigated, and finally optimal electrolyte systems for Li-S cells are suggested.