  We present an x-ray absorption study of the oxidation states of
transition-metal-ions of LiMnO2 and its related materials, widely used as
cathodes in Li-ion batteries. The comparison between the obtained spectrum and
the configuration-interaction cluster-model calculations showed that the Mn3+
in LiMnO2 is a mixture of the high-spin and low-spin states. We found that Li
deficiencies occur in the case of Cr substitution, whereas there are no Li
deficiencies in the case of Ni substitution. We conclude that the substitution
of charge-transfer-type Ni or Cu is effective for LiMnO2 battery materials.
