context: The Li-metal anode is considered an essential component for obtaining the expected Li–S battery performance. This is because of Li's extremely low negative electrochemical potential, very high theoretical specific capacity, and low density. However, the Li-metal anode has additional issues. Safety concerns arise because of the possibility of cell damage or manufacturing failures due to Li-metal's high reactivity, as well as due to the dendrite formation throughout cycling processes which can cause short circuits if dendrites reach the cathode. The electrolyte (salt and solvent) plays a vital role for rapid lithium transport and providing stability even near the highly reactive lithium surface. At the Li surface, electrolyte decomposition due to reduction reactions triggered by their low electrochemical stability leads to the growth of a multicomponent passivating film. This film, known as the solid electrolyte interphase (SEI) may have beneficial passivation properties, or, quite the opposite, may be a cause of irreversible capacity loss. The specific film behavior depends on its chemical composition, structure, and thickness. Moreover, it has been found the SEI properties depend largely on the solvent, salt, and additives used as well as on the electrode structure. Therefore, understanding the role of the electrolyte in SEI formation and its properties should be a useful strategy for controlling dendrite formation, reducing the effects of anode degradation and stabilizing the surface, thus, potentially improving the performance, cycling and safety of the batteries.
answer: Li-metal