A machine-made electrode is shown in Figure . Note that the acoustic density of the machine-made electrode is higher than that of the lab-cast ones, possibly due to higher density of active material (2.0-3.0 g/cm 3 tap density for lithium nickel manganese cobalt oxide (NMC) 22 compared to 0.7 g/cm 3 tap density for lithium manganese iron phosphate (LMFP) ) or densification from calendering. The standard deviation may be used to compare the homogeneity of the lab-made and manufactured electrodes despite their differences in density. For the machine-made electrode, the entire area was used to calculate the standard deviation as it was fully coated with the electrode material, yielding a value of 0.0058 g/cm (n = 11421). On the other hand, a select region in the lab-cast electrode was used, shown as the black dashed box in Figure , to minimize both the area without the electrode (only the current collector present) and feature broadening due to the large transducer diameters (further explained in the Supporting Information, Figures and). From the reduced area, the standard deviation of a baseline electrode was 0.0081 g/cm 3 (n = 10450). Comparing these two electrodes using an F-test on the variance of the acoustic density shows that indeed the lab-fabricated has a larger variance (F test = 1.9897 > F crit = 1.0320), * suggesting that lab-cast electrodes are not as homogeneous as machine-made electrodes. In this particular lab-cast electrode, the large inhomogeneity is likely from the region within the 0.16 g/cm 3 iso-density contour as discussed prior.