POSITIVE ELECTRODE ACTIVE MATERIAL, POSITIVE ELECTRODE, AND LITHIUM ION SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide: a positive electrode active material for a lithium ion secondary battery with a high capacity and a superior capacity-keeping rate in cycle charge/discharge; a positive electrode arranged by use of such a positive electrode active material; and a lithium ion secondary battery including such a positive electrode.SOLUTION: A positive electrode active material comprises a layer structure for a lithium ion secondary battery, which is expressed by the following composition formula: LiNiMO. A lithium ion secondary battery comprises a positive electrode including the positive electrode active material. When the voltage to lithium metal of the positive electrode is represented by V, and the charging capacity of the lithium ion secondary battery is represented by Q in charging the lithium ion secondary battery with a current of 44 Ah/kg based on the weight of the positive electrode active material, a peak value of dQ/dV of a charge curve in a graph of which the horizontal axis shows V, and the vertical axis shows dQ/dV is 190-300 Ah(kg V).SELECTED DRAWING: Figure 4