This paper presents the use of nanometer scale resolution X-ray computed tomography (nano-CT) in the three-dimensional (3D) imaging of a Li-ion battery cathode, including the separate volumes of active material, binder plus conductive additive, and pore. The different high and low atomic number (Z) materials are distinguished by sequentially imaging the lithium cobalt oxide electrode in absorption and then Zernike phase contrast modes. Morphological parameters of the active material and the additives are extracted from the 3D reconstructions, including the distribution of contact areas between the additives and the active material. This method could provide a better understanding of the electric current distribution and structural integrity of battery electrodes, as well as provide detailed geometries for computational models.