Secondary battery

This secondary battery is provided with: a positive electrode containing a lithium-nickel composite oxide; a negative electrode; and an electrolyte solution. In surface analysis of a positive electrode using X-ray photoelectron spectroscopy, the following are detected: a first O1s spectrum having a peak in a bond energy range of 528 eV to 531 eV; a second O1s spectrum having a peak in a bond energy range greater than 531 eV and equal to or less than 535 eV; carrying out B1s spectrum; s2p spectrum; carrying out F1s spectrum; and a Ni3p spectrum. The ratio of the intensity of the first O1s spectrum to the intensity of the second O1s spectrum is 0.5-0.8, the ratio of the intensity of the B1s spectrum to the intensity of the Ni3p spectrum is 0.9-1.8, the ratio of the intensity of the S2p spectrum to the intensity of the Ni3p spectrum is 0.4-1.2, and the ratio of the intensity of the F1s spectrum to the intensity of the Ni3p spectrum is 8-13. 二次电池具备：正极，包含锂镍复合氧化物；负极；以及电解液。在使用了X射线光电子光谱分析法的正极的表面分析中，检测出：在键能为528eV以上且53