Secondary battery-use positive electrode active material, secondary battery-use positive electrode, and secondary battery

A secondary battery-use positive electrode comprising a positive electrode active material, wherein

• the positive electrode active material contains a layered rock salt-type compound,
• the layered rock salt-type compound contains nickel, cobalt, and aluminum as constituent elements,
• when a sum of contents of the nickel, the cobalt, and the aluminum in the layered rock salt-type compound is regarded as 100 parts by mol,
• a content of the nickel is 87 parts by mol or more and 100 parts by mol or less,
• a content of the cobalt is 0 parts by mol or more and 11 parts by mol or less,
• a content of the aluminum is 0 parts by mol or more and 8 parts by mol or less, and
• in surface analysis of the positive electrode active material using X-ray photoelectron spectroscopy, a concentration ratio represented by Formula (1) is 1.60 or less and an intensity ratio represented by Formula (2) is 0.39 or less:
• RX
• =
• X
• ⁢
• 2
• /
• X
• ⁢
• 1
• (
• 1
• )
• where RX is a concentration ratio, X1 is a sum (atom %) of a concentration (atom %) of nickel calculated based on a Ni2p3/2 spectrum, a concentration (atom %) of cobalt calculated based on a Co2p3/2 spectrum, and a concentration (atom %) of aluminum calculated based on an A12s spectrum, and X2 is a concentration (atom %) of a carbonate calculated based on a C1s spectrum,
• RY
• =
• Y
• ⁢
• 2
• /
• Y
• ⁢
• 1
• (
• 2
• )
• where RY is an intensity ratio, Y1 is a peak intensity of the Ni2p3/2 spectrum, and Y2 is a peak intensity of a satellite spectrum derived from the Ni2p3/2 spectrum.

A secondary battery-use positive electrode active material comprising a layered rock salt-type compound, wherein

• the layered rock salt-type compound contains nickel, cobalt, and aluminum as constituent elements,
• when a sum of contents of the nickel, the cobalt, and the aluminum in the layered rock salt-type compound is regarded as 100 parts by mol,
• a content of the nickel is 87 parts by mol or more and 100 parts by mol or less,
• a content of the cobalt is 0 parts by mol or more and 11 parts by mol or less,
• a content of the aluminum is 0 parts by mol or more and 8 parts by mol or less, and
• in surface analysis using X-ray photoelectron spectroscopy, a concentration ratio represented by Formula (1) is 1.60 or less and an intensity ratio represented by Formula (2) is 0.39 or less:
• RX
• =
• X
• ⁢
• 2
• /
• X
• ⁢
• 1
• (
• 1
• )
• where RX is a concentration ratio, X1 is a sum (atom %) of a concentration (atom %) of nickel calculated based on a Ni2p3/2 spectrum, a concentration (atom %) of cobalt calculated based on a Co2p3/2 spectrum, and a concentration (atom %) of aluminum calculated based on an A12s spectrum, and X2 is a concentration (atom %) of a carbonate calculated based on a Cis spectrum,
• RY
• =
• Y
• ⁢
• 2
• /
• Y
• ⁢
• 1
• (
• 2
• )
• where RY is an intensity ratio, Y1 is a peak intensity of the Ni2p3/2 spectrum, and Y2 is a peak intensity of a satellite spectrum derived from the Ni2p3/2 spectrum.