Operando observation of the dynamic SEI formation on a carbonaceous electrode by near-ambient pressure XPS

The dynamic formation of chemical species composing the solid electrolyte interphase (SEI) layer at the surface of a carbonaceous electrode in a carbonate-based liquid electrolyte was observed in real-time using operando near-ambient pressure XPS (NAP-XPS). The potential of the glassy carbon electrode vs. metallic lithium was controlled during the XPS experiment. By following the binding energy shifts as a function of applied potential, we could identify the main SEI species and observe their deposition on the electrode surface during the formation of the SEI. These results demonstrate that NAP-XPS is a powerful tool to investigate the SEI formation and stability in Li- and post-Li-ion batteries, paving the way for future studies on the effect of electrolyte additives and solvent mixtures on battery performance.