Ultrasound waves transmitted through electrode films were recorded at every point of a grid set by steps in the x-and z-directions of a 3D printer gantry and then further processed to obtain an acoustic density map. A schematic of this process is shown in Figure . The an approximate mass density, ρ V , of 1 g/cm 3 . This is likely to be a convolution of the propagated wave frequency, the propagating medium, and porosity and tortuosity of the material. Nonetheless, the acoustic mass density can still provide meaningful insight into the quality of the electrode. iso-density contour appears in the acoustic image, suggesting a local higher mass loading, but since it is not as expansive as the one covered by the 0.14 g/cm 3 contour, this increased acoustic density could be the result of large particles or poor suspension of materials from slurry mixing leading to more mass deposition. These features show possible mass inhomogeneity throughout the electrode from acoustic density mapping.