Vijayakumar Murugesan1 Kee Sung Han1 Manjula Nandasiri1 Shuttha Shutthanandan1 Thevuthasan Sunthrampillai1 Perla Balbuena2 Karl Mueller1

1, Pacific Northwest National Laboratory, Richland, Washington, United States
2, Texas A&M University, College Station, Texas, United States

Comprehensive understanding about the solid electrolyte interphase layer (SEI) is the major knowledge gap in the development of the lithium sulfur (Li-S) batteries. Various ex situ studies, about the interfacial reaction mechanism gave overly simplistic views that lapse the transient species/structures that are critical to interfacial process. However, the underlying challenge is to detect, identify and quantify the reactions at the interface which typically span over a wide spatial and temporal region and are inaccessible by any single spectroscopic and/or classical computational methods. Hence, it is critical to develop in situ multimodal approach that can provide unprecedented chemical imaging of complex interfaces in wide lateral (ranging from subatomic to micron) and temporal scales (few ns to seconds). Herein, we report an in-situ X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and nuclear magnetic resonance (NMR) combined with ab initio molecular dynamics (AIMD) computational modelling to gain fundamental understanding about the complex interfacial interactions in Li-S batteries. A multimodal approach involving AIMD modelling and in situ XPS and NMR characterization uniquely reveals the chemical identity and distribution of active participants of interfacial reactions as well as SEI layer evolution mechanism.