Direct visualization of initial SEI morphology and growth kinetics during lithium deposition by in situ electrochemical transmission electron microscopy.

Deposition of Li is a major safety concern existing in Li-ion secondary batteries. Here we perform the first in situ high spatial resolution measurement coupled with real-time quantitative electrochemistry to characterize SEI formation on gold using a standard battery electrolyte. We demonstrate that a dendritic SEI forms prior to Li deposition and that it remains on the surface after Li electrodissolution.