Observation of Valence State Change in Layered Li_(1-y)Ni_(1/3)Mn_(1/3)Co_(1/3)O_2

摘要

Valence state changes in Li1?yNi1/3Mn1/3Co1/3O2 were investigated using hard and soft X-ray absorption fine structure (XAFS) measurements. Reversible changes in the MO bond lengths and in the position of the M L-edge peak (M = Ni, Co) were observed during the first charge and discharge cycle. These results demonstrate that Li de-intercalation/intercalation proceeds mainly by changes in the valence states of the Ni and Co cations. In addition, it has been shown that the host material LiNi1/3Mn1/3Co1/3O2 had a surface structure free of Li2CO3.