Murata Manufacturing Co., Ltd.

Kensuke Sameshima

Yosuke Hosoya

Yuki Niwata

Saurabh Ranjan

A secondary battery includes a positive electrode including a positive electrode active material, a negative electrode, and an electrolytic solution. The positive electrode active material includes a lithium composite oxide of a layered rock-salt type. The lithium composite oxide includes lithium, cobalt, aluminum, magnesium, an additional element, and oxygen as constituent elements. The additional element includes at least one of fluorine, phosphorus, or sulfur. According to an analysis of the positive electrode active material by inductively coupled plasma optical emission spectrometry, a content of aluminum is greater than a content of magnesium. According to an analysis of a surface of the positive electrode active material by X-ray photoelectron spectroscopy, a sum of an abundance of chemical bonds between magnesium and oxygen and an abundance of chemical bonds between magnesium and the additional element is greater than a sum of an abundance of chemical bonds between aluminum and oxygen and an abundance of chemical bonds between aluminum and the additional element.

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Kyoto, Japan

Kensuke Sameshima