SECONDARY BATTERY

A secondary battery includes a positive electrode, a negative electrode, a negative electrode wiring line, and an electrolytic solution. The negative electrode wiring line is coupled to the negative electrode. The negative electrode includes a negative electrode active material layer and a film. The film covers a surface of the negative electrode active material layer. The film includes sulfur as a constituent element. The electrolytic solution includes a chain carboxylic acid ester. Where the film is divided, in a direction away from the negative electrode wiring line, into thirds including a first film part, a second film part, and a third film part: a content of sulfur in the first film part, the third film part, or each of the first film part and the third film part is greater than or equal to 11 μmol/mand less than or equal to 22 μmol/m; a content of sulfur in the second film part is greater than or equal to 7 μmol/mand less than or equal to 13 μmol/m; and a ratio of the content of sulfur in the first film part, the third film part, or each of the first film part and the third film part to the content of sulfur in the second film part is greater than or equal to 1.2 and less than or equal to 2.1.