Electrolyte solutions for “beyond li-ion batteries”: Li-S, Li-O₂, and mg batteries

This article describes electrolyte solutions aspects of three battery systems considered as "beyond Li-ion batteries." The common denominator of these systems is the importance of the nature of the electrolyte solutions, which determines their reversibility. Li-S batteries are very close to practical importance, offering the highest energy density among rechargeable batteries. Li-oxygen systems are theoretically most promising, but the poor compatibility of most polar-aprotic solvents with the oxygen reduction species is a major obstacle for practical development. Developing rechargeable Mg batteries also involves a challenge in the choice of electrolyte solutions compatible with both reversible Mg anodes and high potential/high capacity Mg ions insertion cathodes.