 Lithium cobalt oxide ( <unk> ) is widely used in lithium ion battery cathodes . The material is composed of cobalt oxide layers in which the lithium is intercalated . During discharge , the lithium released as lithium ion . Nickel @-@ cadmium ( <unk> ) and nickel metal hydride ( <unk> ) batteries also include cobalt to improve the oxidation of nickel in the battery . 
