Owing to recent developments in cryogenic TEM for materials science, it becomes possible to image Li-based battery materials in the TEM without side reactions and beam damage. The chemistry and nanostructure of the SEI can now be visualized and directly correlated to battery performance, offering unprecedented insight into electrochemical behavior and aging phenomena within batteries. In this talk, William Huang highlighted his recent work using cryo-TEM to understand SEI properties and failure modes in next-generation silicon and metallic lithium anodes.