Lithium manganese composite oxide for lithium secondary battery cathode active material, manufacturing method thereof, and lithium secondary battery using the composite oxide as cathode active material

Abstract

One of the most important subject of the present invention is to provide a new lithium manganese composite oxide which does not include the cobalt which is few as the resource and expensive. For the above purpose, a lithium manganese composite oxide for a lithium secondary battery cathode active material represented by a composition formula of Li1−x Ax MnO2 (A is an alkali metal except for Li:0<x<1) and having a layered structure with a rock salt type ordered cations is adopted. According to the lithium manganese composite oxide, the crystal structure is stabilized since the lithium site of the layered structure LiMnO2 is replaced by the atom of alkali metal element having larger ionic diameter than the lithium ion. Accordingly, not only large discharge capacity is maintained but the cycle characteristic is excellent. In addition, since the lithium manganese composite oxide does not include the cobalt, it can be manufactured in low cost. The present invention can also provide a simple and cheap manufacturing method of the above lithium manganese composite oxide, and a cheap lithium secondary battery which uses the above lithium manganese composite oxide as the cathode active material.

Dependencies are inferred from the claim text.