Combining Experimental and Computational Techniques to Understand the Role of Native Oxide on the Solid Electrode Interphase Formation on Si Electrode in Li-Ion Batteries

With the current surge in energy demand for electrification of transportation, developing high energy storage devices is essential. Si anode based Li-ion batteries offer huge promise in this regard by providing high theoretical capacity of 3579 mAh/g, 10 times higher than graphite anode based Li-ion batteries (LIBs). One of the major contributor to capacity fade in Li-ion batteries is the uncontrolled growth of the solid-electrolyte interphase (SEI) layer. SEI is formed due to the decomposition of electrolytes and consumes Li ions. Despite a significant amount of work on SEI, our understanding of both its formation and growth is still limited. In this work, we studied the lithiation mechanism of the inevitable native oxide on the Si surface, identified the stable phases formed due to the lithiation and determined how these stable phases become part of the SEI by using Ab-initio molecular dynamics, X-Ray photoelectron spectroscopy (XPS) and X-Ray reflectivity (XRR). This fundamental understanding of SEI formation would enable to find better strategies for designing high-performance LIBs.