In this work, the phase diagram of LixCoO2 is calculated from first pr
inciples for x ranging from 0 to 1. Our calculations indicate that the
re is a tendency for Li ordering at x=1/2 in agreement with experiment
[J. N. Reimers and J. R. Dahn, J. Electrochem. Sec. 139, 2091 :1992)]
. At low Li concentration, we find that a staged compound is stable in
which the Li ions selectively segregate to every other Li plane leavi
ng the remaining Li planes vacant. We do not find the two-phase region
observed at high Li concentration and speculate that this two-phase r
egion is caused by the metal-insulator transition that occurs at conce
ntrations slightly below x =1.