This work used cryogenic transmission electron microscopy (“cryo-EM”) to visualize the SEI on carbon electrodes. Cryo-EM enables atomic-resolution microscopy with minimal air exposure and beam damage. We found two morphologies of SEI growth: compact SEI (~2 nm) and extended SEI (~100s of nm), consistent with the SEI literature. However, we find that instead of observing both morphologies on a single particle, as was previously hypothesized, these morphologies are present on individual particles. These results highlight the complexity of the SEI and highlight the power of cryo-EM as a characterization tool.