POSITIVE ELECTRODE FOR SECONDARY BATTERY, AND SECONDARY BATTERY

WIPO Patent Application WO/2021/220743

A1

This secondary battery comprises: a positive electrode including a positive electrode active material layer; a negative electrode; and an electrolyte, wherein the positive electrode active material layer contains a layered rock salt-type lithium nickel composite oxide represented by formula (1). The ratio X of the atomic concentration of Al to the atomic concentration of Ni on the surface of the positive electrode active material layer analyzed using X-ray photoelectron spectroscopy satisfies the condition represented by expression (2). The ratio Y of the atomic concentration of Al to the atomic concentration of Ni inside (depth = 100 nm) the positive electrode active material layer analyzed using X-ray photoelectron spectroscopy satisfies the condition represented by expression (3). The ratio Z of the ratio X to the ratio Y satisfies the condition represented by expression (4). In the surface analysis of the positive electrode using X-ray photoelectron spectroscopy, B1s spectrum, S2p spectrum, F1s spectrum, and Ni3p spectrum are detected. The ratio IBN of the intensity of the B1s spectrum to the intensity of the Ni3p spectrum satisfies the condition represented by expression (5). The ratio ISN of the intensity of the S2p spectrum to the intensity of the Ni3p spectrum satisfies the condition represented by expression (6). The ratio IFN of the intensity of the F1s spectrum to the intensity of the Ni3p spectrum satisfies the condition represented by expression (7).　(1): LiaNi1-b-c-d CobAlcMdOe (M is at least one among Fe, Mn, Cu, Zn, Cr, V, Ti, Mg, and Zr. a, b, c, d, and e satisfy 0.8