Sanyo Electric Co., Ltd.

Masahiro Shiraga

Kei Kobayashi

Tatsuki Hiraoka

Yoshiyuki Muraoka

Taizou Sunano

It is an object to improve the initial charge-discharge efficiency of a nonaqueous electrolyte secondary battery that uses, as negative electrode active materials, a carbon material and a metal or metal oxide that forms an alloy with lithium. There is provided a nonaqueous electrolyte secondary battery including a positive electrode, a nonaqueous electrolyte, and a negative electrode which includes, as negative electrode active materials, a carbon material and a metal or metal oxide that forms an alloy with lithium and in which at least part of a surface of the carbon material is coated with a polymer material that does not react with lithium. The mass percentage of the polymer material that does not react with lithium relative to the carbon material is preferably 0.5 to 2 mass %.

Negative electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery

The initial charge/discharge efficiency and cycle characteristics of a nonaqueous electrolyte secondary battery are improved. Provided is a nonaqueous electrolyte secondary battery including a positive electrode, a negative electrode, a porous layer placed on the negative electrode, a separator, and a nonaqueous electrolyte. The porous layer has flat voids. The minor axis direction of each flat void is perpendicular to the plane direction of the porous layer and the major axis direction of the flat void is parallel to the plane direction of the porous layer. The ratio of the major axis to the minor axis of the flat void preferably ranges from 1.4 to 2.2.

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Hyogo, Japan

Masahiro Shiraga