Hitachi Maxell, Limited

Seiji Ishizawa

Toshihiro Abe

Hiroshi Abe

Akira Inaba

Tomohito Sekiya

Yuji Hashimoto

Susumu Yoshikawa

There is provided a lithium ion secondary battery with a high capacity and having excellent cycle characteristics. The lithium ion secondary battery, including a positive electrode, a negative electrode, a separator and a nonaqueous electrolyte liquid. Here, the positive electrode comprises a positive electrode material in which a surface of particles of a positive electrode active material is coated with an Al-containing oxide. The Al-containing oxide has an average coating thickness of 5 to 50 nm. The positive electrode active material contained in the positive electrode material comprises a lithium cobalt oxide comprising Co and at least one kind of an element Mselected from the group consisting of Mg, Zr, Ni, Mn, Ti and Al. The negative electrode comprises a material S including SiO(0.5&#x2266;x&#x2266;1.5) as a negative electrode active material, wherein in 100 mass % of a total of the negative electrode active material included in the negative electrode, the materials S is included in the negative electrode active material at a content of 10 mass % or more.

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Ibaraki, Japan

Seiji Ishizawa