Murata Manufacturing Co., Ltd.

Tomomi Sakuma

Raman Kukreja

Hideki Nakai

Masahiro Miyamoto

Shinichi Katayama

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The negative electrode includes a film covering a negative electrode active material layer. The electrolytic solution includes a chain carboxylic acid ester. According to an analysis of the film by inductively coupled plasma optical emission spectroscopy, a content of boron in the film is greater than or equal to 10 μmol/mand less than or equal to 30 μmol/m, a content of sulfur in the film is greater than or equal to 20 μmol/mand less than or equal to 70 μmol/m, and a ratio of the content of sulfur to the content of boron is greater than or equal to 1.0 and less than or equal to 3.0.

Secondary battery having a film covering a negative active material layer

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.

Secondary battery

A lithium-ion secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution that includes an alkoxy compound represented by CX—O—(CX)—OH. Each X represents hydrogen (H) or a halogen, m is an integer of 1 or greater, n is an integer of 1 or greater, and (m+n) is 4 or greater.

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Kyoto, Japan

Tomomi Sakuma