Observation of Valence State Change in Layered Li1−yNi1/3Mn1/3Co1/3O2

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 M–O 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.