Novel Electrolyte Development for In Situ Formed Li-Metal Batteries Using Amplified Solid Electrolyte Interphase and Plating Investigations

Abstract

Li-metal anodes can provide high energy density battery configurations, but their practical use is hindered by safety concerns and poor efficiencies due to non-ideal lithium plating. In utilizing ultra-low areal plating capacities (0.08 mAh cm−2, LCP) within Li-metal half-cells, it was found that the initial formation efficiency of the SEI can be amplified and correlated with initial losses and capacity fade over time under higher areal plating capacities (2.5 mAh cm−2, 4.0 mAh cm−2, and 6.5 mAh cm−2) within an in-situ formed anodeless LCO configuration. Herein, these techniques have been utilized to introduce and optimize novel fluoroganosiyl (FOS) based dual salt electrolytes for use in in-situ formed Li-metal batteries, achieving initial cycling loss of <3% (at 4.0 mAh cm−2). Further characterization of the functional benefit of this electrolyte was elucidated using XPS surface analysis, revealing unique Li-C-N, Li3N, Si, and B-N chemistries that likely contribute to the formation of a robust SEI.