Building Better Lithium‐Sulfur Batteries—A Reassessment of the Working Mechanism

Abstract Lithium‐sulfur (Li−S) batteries have captured global attention and in‐depth research interest. Nevertheless, its massive commercialization has been bothered by the “shuttle effect” caused by the soluble Li polysulfides (LiPSs) and unremitted growth of Li dendrites originated from unstable solid electrolyte interphase (SEI) film. Over the few decades have witnessed the remarkable progress of Li−S batteries, while several controversial views on the working mechanism have emerged in recent three years, which are challenging for previous related research. In this perspective, we give a brief review on the latest studies and reassess the working mechanism of Li−S batteries. With this regard, we start with a simple introduction to emphasize the significance of developing Li metal batteries. Then, we specifically elucidate the formation process and composition of SEI film. Next, we detailly discuss LiPSs cation as the dominant species in Li−S battery. Subsequently we review the case that contend no LiPSs intermediates formation in Li−S battery using γ‐S as the cathode. Afterwards, we conduct a discussion between dry SEI film vs. wet SEI film on the surface of Li metal anode, followed by the strategies to design rational electrolytes for engineering stable Li metal anodes. Finally, we propose personal insights and perspectives on the development direction of Li−S batteries. We hope this timely perspective will be of great interest to the numerous scientific researchers focusing on Li−S batteries.