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A lithium ion secondary battery comprising a positive electrode, a negative electrode, and an electrolyte solution:
wherein:
the positive electrode comprises a positive electrode active material comprising a positive electrode active material particle, the positive electrode active material particle comprising lithium cobalt oxide, magnesium, and aluminum,
a magnesium concentration in a surface portion of the positive electrode active material particle is higher than a magnesium concentration in an inner portion of the positive electrode active material particle,
in an EDX linear analysis of the positive electrode active material particle, a concentration peak of aluminum is located in a deeper region than a concentration peak of magnesium,
the positive electrode active material has an O3 crystal structure when a charge depth of the positive electrode active material is 0.06 or less,
an X-ray diffraction pattern of the positive electrode active material has at least a first diffraction peak at 2θ of 19.30+0.20° and a second diffraction peak at 2θ of 45.55=0.10° when the positive electrode is analyzed by powder X-ray diffraction by using CuKal ray, when a battery comprising the positive electrode and a counter electrode of lithium is charged at 4.6V, and
the electrolyte solution comprises vinylene carbonate.