Ni, Co, and Mn L3-edge X-ray absorption micro-spectroscopic study on LixNi0.88Co0.08Mn0.04O2 primary particles upon annealing from room temperature to 800

LixNi0.88Co0.08Mn0.04O2 primary particles for lithium ion battery (LIB) applications were annealed in situfrom room temperature (RT) to 200, 400, 600, and 800 C. At each of these temperatures, space-resolvedNi L3-, Co L3-, and Mn L3-edge X-ray absorption spectra of the particles were acquired with 30 nm focusedX-rays by using synchrotron-based scanning transmission X-ray microscopy (STXM). This study aimed toinvestigate the changes induced by the annealing temperature in the local oxidation number, phase, andmicroscale shape within the particles. At RT, the average oxidation numbers of the Ni, Co, and Mn ionswere +3, +3, and +4, respectively. At 200 C, the average oxidation numbers of the Co and Mn ions werebasically the same as those at RT, and those of the Ni ions were between +2 and +3. At 400 C, the averageoxidation numbers of the Ni and Co ions decreased to +2, whereas that of the Mn ions was +4. The averageoxidation number of the Ni ions was noticeably lower for smaller particles and on the edges of the particles. At 600 C, the Ni and Co ions were mostly in the metallic state, the Mn ions were reduced to anoxidation number of +2, and the distribution of Mn ions differed from that of the Ni and Co ions. At800 C, the Ni and Co ions were mostly in the metallic state, and the oxidation number of the Mn ionswas predominantly +2. At this temperature, strong changes in density distributions of the Mn, Ni, andCo ions occurred. KCI Citation Count: 0