To gain a better understanding of correlations between microstructure features and intrusion initiation, we examined the sub-surface LLZO morphology using FIB cross-sectional milling before and after intrusions in the same microscope. For the pristine LLZO (without any electrochemistry performed), the subsurface FIB milling revealed a small number of pores (~0.5 µm in diameter) as well as some regions of SEM contrast (see Figure for images). Some of these pores are partially filled with an unknown material, even before any lithium plating occurred, possibly from impurities in the material or generated from FIB damage. We also examined the surface and subsurface morphology after application of a 5 mN force using the tungsten microprobe, but prior to lithium plating. As shown in Figures and, we did not observe large changes in morphology upon contact, either on or below the surface after FIB milling. However, upon repeated indentation at high forces, we did observe chipping of the surface.