Delineating the Lithium–Electrolyte Interfacial Chemistry and the Dynamics of Lithium Deposition in Lithium–Sulfur Batteries

Abstract

AbstractStabilizing the metallic lithium anode is the major roadblock to realizing long cycle life lithium‐sulfur (Li–S) batteries with high energy density. The chemistry of the dynamically evolving solid‐electrolyte interphase layer on the lithium surface is critical to achieving reversible plating and stripping of lithium. Herein, electrolyte formulations are carefully varied and employed to modulate the composition, and thereby, the properties of the lithium‐electrolyte interface. The impact of these changes in the interfacial chemistry on the dynamics of lithium deposition is evaluated by tracking cyclability in an anode‐free full cell configuration. Critical insights are revealed on the role of different components of the electrolyte and their interplay, including various functional groups in the electrolyte salt, oxidizing effect of lithium nitrate, and the intrinsically stabilizing effect of polysulfide species, in determining the characteristics of lithium deposition and lithium cycling efficiency. The study illuminates the key elements underlying the unique chemistry of the lithium–electrolyte interface in Li–S batteries and it can spur further development of novel strategies toward stabilizing the lithium‐metal anode in the Li–S system.