Relationship between changes in ionic radius and lattice dimension of lithium manganese oxide spinels during lithium insertion/extraction

摘要

Dimensional stability is critical for the cyclability of Li insertion materials in Li-ion batteries. Thus, in this study, we characterize the dimensional change in a series of spinel-structured Li-Co-Mn oxides (LiCoxMn2-xO4) during Li insertion using ex-situ X-ray diffraction technique. We deduce that a change in the cubic lattice parameters of the LiCoxMn2-xO4 compounds during Li insertion depends on the solid-state redox reactions; in particular, a smaller dimensional change is observed for the Co-3(+)/Co-4(+) redox reaction, while a larger change is observed for the Mn3+/Mn4+ redox reaction. Through our X-ray diffraction studies, a linear relationship between the change in ionic radii of the redox species and dimensional change in the lattice structure of the compounds was observed during the reactions, which can be adopted for other Li-Mn oxide spinels as well. Hence, this relationship provides useful insight for designing Li insertion materials with high dimensional stability for long-life Li-ion batteries.