Shape Determination in Lithium-Ion Battery Cathode Materials Using Electron Diffraction-Assisted Electron Tomography

Commercial cathode materials used in lithium ion batteries such as lithium transition metal oxides usually consist of 5 to 10 micron-sized, spherical secondary particles. These particles consist of primary particles that are connected to each other akin to seeds in a pomegranate. These primary particles are nearly equiaxed in shape and highly faceted. Recent aberration-corrected STEM-based studies have shown that the select facets of these particles consists of a thin layer of spinel phase The spinel phase is formed specifically on the facets that correspond to the diffusion path of lithium ions. For example, in Li-and Mn-rich transition metal oxides (LMRTMO), they form on {131}monoclinic facets but do not form on the stable (001)monoclinic facets. To completely understand the intercalation and phase transformation mechanisms in these materials, it is important to characterize the morphological shape of these particles.