In the last decade, lithium ion batteries held a major role in the path towards personal electronics due to being lightweight and providing a high energy density. However, several problems have been identified with lithium ion batteries. Due to inherent instability, lithium ion batteries are known to have issues with safety and capacity loss. Our goal is to advance the understanding of the electrochemical processes, specifically the interfacial processes at the anode, to continue their advancement in our electronic age. At the interface of the electrolyte and anode, during the first several charging and discharging cycles, appears a protective layer by interaction of decomposed electrolyte at the electrode surface. This protective layer, termed the solid electrolyte interphase, is of particular importance as it increases the stability, impeding dendrite growth, and ultimately leading to improved capacity and safety. Our electrolyte is a lithium salt (LiClO4) with ethylene carbonate (EC) in a tetrahydrofuran (THF) solvent, leading, primarily, to one of the main SEI contributors, lithium ethylene dicarbonate (LiEDC). By spectroscopically probing the interface with sumfrequency generation and simultaneously scanning with cyclic voltammetry, we are able to see the SEI contribution formation in real time.Ope
