AES lithium chemical mapping in buried interface of all-solid-state battery materials

All-solid-state batteries (ASSBs) have been attracting attention as the next generation batteries. Despite the growing interest, there are still many challenges faced in the commercial use of ASSBs. One of the biggest issues is the internal resistance generated at the interface between solid electrolyte (SE) and electrode. Understanding the solid-solid interactions requires chemical analysis near the interface. Auger electron spectroscopy (AES) is a suitable surface analysis technique to determine the lithium chemical state with high spatial resolution. However, SEs are often sensitive to electron beam irradiation, and the chemical state of SEs is easily changed during measurement. Therefore, in this study, scanning Auger microprobe (SAM) incorporated into a multitechnique XPS system was used to evaluate the electron beam damage on a LiPON (lithium phosphorus oxynitride) surface, and then the optimal conditions for AES mapping were determined. Using the optimal conditions, lithium chemical maps from LiPON/LiCoO2 cross-section were obtained. In this paper, the results of quantitative examination of electron beam damage on LiPON surface and lithium chemical mapping will be discussed.