Current direct observations of the SEI and Li metal are largely based on the two-dimensional imaging techniques, where the 3D spatial relationships are undetermined. Transmission X-ray microscopy (TXM) is widely used to perform nano-computed-tomography (nano-CT) for energy science , especially for Li-ion batteries . One main advantage of imaging by X-ray CT over other techniques is that it is non-destructive. However, a typical nano-CT can practically reach a resolution of only 30-60 nm . While it is suitable for electrode-level structural characterization, the resolution falls short of providing sufficient details to delineate subparticle heterogeneity. Specifically, the diameters of Li metal dendrites are on the order of a few hundred nanometers and SEI is typically tens of nanometers, which correspond to a few or even less than one pixel in an X-ray CT image. In addition, X-ray tomography is less ideal for light elements like H and Li due to less X-ray absorption and low contrast in projection images. On the contrary, electron tomography works well with light elements and can reach subnanometer resolution in TEM .