Neutron and X-ray linear attenuation coefficients at 0.18 nm neutron wavelength and 26.9 keV X-ray energy respectively for the battery materials of interest. We have used the peak X-ray energy for calculating 𝝁 𝐗_𝐭𝐨𝐭 , which is a valid approximation given the materials thickness in the anodes. We computed the X-ray coefficients from tabulated material cross sections. For graphite, database-derived values for both neutron and X-rays took its composition and porosity into consideration. For LiOH and copper, we assumed fully dense materials for the calculations. Detailed calculations are given in Supporting Information#2. anode (cyan ellipse in A). However, in the cycled anode, graphite is distinguishable from Cu because they are physically separated from each other (cyan ellipses in B). X-ray images of both the pristine and cycled anodes show Cu (yellow ellipses). Graphite can be seen very faintly in the X-ray slices when it is physically far from Cu (orange ellipse in B). X-ray beam hardening artifacts are evident as dark streaks around the edges of Cu (pink circles). The decreasing diameter and thickness of the outer glass capillary in the images from left to right in (A) is due to its funnel-like geometry. The grayscale bar on the right has arbitrary units (a.u.) and was created using 32-bit images in ImageJ.