The effect of a metal-oxide coating on the cycling Behavior at 55° C in orthorhombic LiMnO2 cathode materials

The structural stability of metal-oxide-coated orthorhombic LiMnO2 (o-LiMnO2) was characterized by its 55degreesC cycling behavior. Sol-gel coating of the metal oxides (Al2O3 and CoO), followed by heat-treatment at 400degreesC, leads to the formation of the solid-solution layer (LiMn1-xMxO2) with a concentration gradient of metal atoms at the particle surface. The specific capacity and cycle life at 55degreesC are influenced significantly by the metal-oxide coating. CoO-coated LiMnO2 exhibits an additional voltage plateau at the deep discharge (2 V), and has a higher capacity than Al2O3-coated electrode, although the capacity retention is inferior to the Al2O3-coated cathode. (C) 2002 The Electrochemical Society.