Changes in chemical bondings by Li deintercalation in LiMO2. (M = Cr, V, Co and Ni)

First principles molecular orbital calculations for LiMO2- and MO2 have been carried out using the discrete variational X alpha cluster method. Li in LiMO2 is nearly completely ionized. Strong covalent interaction between hi and O is noted. The removal of Li significantly increases the interaction between M and Q. This results in the "oxidation" associated with the de-intercalation not of M but of O. The formal redox notation for the de-intercalation. i.e.. M(IV)/M(III), is thus far from reality. The difference in the de-intercalation capability among four LiMO2 compounds is ascribed to the difference in the magnitude of electrostatic repulsion between the oxygen layers in MO2.