Positive electrode for secondary battery, and secondary battery

A secondary battery comprising:

• a positive electrode including a positive electrode active material layer;
• a negative electrode;
• and
• an electrolytic solution, wherein
• the positive electrode active material layer includes a lithium-nickel composite oxide of a layered rock-salt type represented by Formula (1) below,
• according to an analysis of the positive electrode active material layer performed at a surface of the positive electrode active material layer by X-ray photoelectron spectroscopy, a ratio X of an atomic concentration of Al to an atomic concentration of Ni satisfies a condition represented by Expression (2) below,
• according to an analysis of the positive electrode active material layer performed at an inner part at a depth of 100 nanometers of the positive electrode active material layer by the X-ray photoelectron spectroscopy, a ratio Y of the atomic concentration of Al to the atomic concentration of Ni satisfies a condition represented by Expression (3) below,
• a ratio Z of the ratio X to the ratio Y satisfies a condition represented by Expression (4) below,
• a B1s spectrum, an S2p spectrum, an F1s spectrum, and an Ni3p spectrum are detectable by a surface analysis of the positive electrode by the X-ray photoelectron spectroscopy,
• a ratio IBN of an intensity of the B1s spectrum to an intensity of the Ni3p spectrum satisfies a condition represented by Expression (5) below,
• a ratio ISN of an intensity of the S2p spectrum to the intensity of the Ni3p spectrum satisfies a condition represented by Expression (6) below, and
• a ratio IFN of an intensity of the F1s spectrum to the intensity of the Ni3p spectrum satisfies a condition represented by Expression (7) below,
• LiaNi1-b-c-dCObAlcMdOe (1)
• where
• M is at least one of Fe, Mn, Cu, Zn, Cr, V, Ti, Mg, or Zr;
• and
• a, b, c, d, and e satisfy 0.8<a<1.2, 0.06≤b≤0.18, 0.015≤c≤0.05, 0≤d≤0.08, 0<e<3, 0.1≤(b+c+d)≤0.22, and 4.33≤(1−b−c−d)/b≤15.0,
• 0.30≤X≤0.70 (2)
• 0.16≤Y≤0.37 (3)
• 1.30≤Z≤2.52 (4)
• 0.9≤IBN≤1.8 (5)
• 0.4≤ISN≤1.2 (6)
• 8≤IFN≤13 (7).