Investigation on lithium de-intercalation mechanism for LiNi0.45Mn0.45Al0.1O2

Li1−yNi0.45Mn0.45Al0.1O2 was synthesized and characterized using both XRD and XANES measurements. The Li/Li1−yNi0.45Mn0.45Al0.1O2 cell showed a discharge capacity of 125 mAh/g in the voltage range 4.5–2.5 V. The Ni K and LII,III-edge XANES results indicated that the Li de-intercalation from LiNi0.45Mn0.45Al0.1O2 proceeded mainly by the valence state change of Ni ions over the whole composition range. Structural analysis clarified that most of the Li ions and a small fraction of the Ni ions migrated from the octahedral 3a site to the tetrahedral 6c site with Li de-intercalation. This observed structural change was similar to that of Li1−yNi0.5Mn0.5O2, indicating that this structural change is characteristic in the Li(NiMn)O2 system.