Sumitomo Metal Mining Company, Ltd.

Panasonic Energy Co., Ltd.

Yoshiyuki Matsuura

Kazuomi Ryoshi

Takahiro Toma

Takahiro Ogawa

A positive electrode active material for a lithium ion secondary battery contains a lithium metal composite oxide. The lithium metal composite oxide includes lithium (Li), nickel (Ni), cobalt (Co), and element M (M) in a mass ratio of Li:Ni:Co:M=1+a:1−x−y:x:y (wherein −0.05≤a≤0.50, 0≤x≤0.35, 0≤y≤0.35, and the element M is at least one element selected from Mg, Ca, Al, Si, Fe, Cr, Mn, V, Mo, W, Nb, Ti, Zr, and Ta), wherein when a line analysis is performed with STEM-EELS from a surface of a particle of the lithium metal composite oxide to a center of the particle in a cross-section of the particle during charging at 4.3 V (vs. Li/Li), a thickness of an oxygen release layer, in which an intensity ratio of a peak near 530 eV (1st) to a peak near 545 eV (2nd) at an O-K edge is 0.9 or less, is 200 nm or less.

Positive electrode active material for lithium ion secondary battery, method of manufacturing positive electrode active material for lithium ion secondary battery, and lithium ion secondary battery

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Ehime, Japan

Yoshiyuki Matsuura