The present invention provides a powderous lithium transition metal oxide
with the composition as represented by the below Formula and prepared by
solid state reaction in air from a mixed transition metal precursor and
Li.sub.2CO.sub.3, with being practically free of Li.sub.2CO.sub.3
impurity: Li.sub.xM.sub.yO.sub.2 wherein M=M'.sub.1-kA.sub.k, where
M'=Ni.sub.1-a-b(Ni.sub.1/2Mn.sub.1/2).sub.aCo.sub.b on condition of
0.65.ltoreq.a+b.ltoreq.0.85 and 0.1.ltoreq.b.ltoreq.0.4; A is a dopant;
and 0.ltoreq.k.ltoreq.0.05; and x+y=2 on condition of
0.95.ltoreq.x.ltoreq.1.05. The Ni-based lithium transition metal oxide
according to the present invention has a well-layered structure, and also
improved safety, cycling stability and stability against aging and low
gas evolution during storage, when used as an active material for cathode
of lithium secondary batteries, because it has a high sintering stability
and is substantially free of soluble bases.Moreover, the lithium
transition metal oxide of the present invention can be prepared by a
low-cost process using a mixed transition metal precursor and
Li.sub.2CO.sub.3 as raw stocks and under relatively unrestricted
conditions.