(644g) Nonpolar-Based Electrolytes for Improved Lithium Metal Deposition and Stripping

Lithium metal batteries have generated intense research interest because of their high theoretical energy densities that dwarf current lithium-ion batteries. However, the low lithium reduction potential and its high reactivity has plagued current lithium metal-based batteries. Current work has focused on developing reactive additives that can passivate the lithium surface, thereby decreasing reactivity between lithium metal and the polar electrolyte solvent. However, continuous consumption of the additive is detrimental to longer-term cycling. In this work, we explore an alternative strategy of nonreactive additives that are permanently present within the electrolyte to limit reaction of the polar solvent with the lithium metal surface. We show that nonpolar solvents, when added to typical ether electrolytes, can double the cycle life of lithium metal batteries. Furthermore, we show significant decrease in lithium nucleation and growth overpotentials, an improved lithium deposition morphology, and an extension of the oxidative stability of the electrolyte. By engineering and controlling the solvation structure within the electrolyte, this work brings us closer to developing longer-lasting lithium metal batteries.