This invention relates to complex lithium metal oxides, which are cathode
active materials of a lithium or lithium ion secondary battery with
enhanced cycle life and safety, and a process for preparation thereof.
The core particles are complex lithium metal oxides capable of absorbing,
storing and emitting lithium ions, and a coating layer comprised of
amorphous complex lithium cobalt oxides that are formed on the surface of
the core particle, which is structurally stable and inactive with
electrolytes. Because the amorphous complex lithium cobalt oxides are
inactive with electrolytes, the oxides stabilize the surface structure of
the complex lithium metal oxide and improve on high temperature storage
properties, as well as safety and cycle life.