Spinel Type Lithium Nickel Manganese-Containing Composite Oxide

Provided is a 5 V class spinel type lithium nickel manganese-containing composite oxide having an operating potential of 4.5 V or more with respect to a metal Li reference potential, wherein the composite oxide is able to improve cycle characteristics while suppressing the amount of gas generated under high temperature environments and, moreover, to improve output characteristics while suppressing a shoulder on discharge at around 4.1 V in a charge and discharge curve. The spinel type lithium nickel manganese-containing composite oxide is represented by a general formula [Li(LiNiMnTiMgM)O] (where 0