Murata Manufacturing Co., Ltd.

Sho Takahashi

Yukio Miyaki

Moriaki Okuno

Masaki Kuratsuka

Kazuki Honda

Takashige Fujikawa

Atsushi Ouki

Takamasa Ono

Ryuji Soeda

Shoichi Nishiyama

Masumi Fukuda

Yosuke Kono

Takahisa Ishimatsu

Atsushi Nemoto

Yoshihito Akiyama

Shinji Hayazaki

Takeo Asanuma

Susumu Endo

Takahiro Shirai

Takuma Kawahara

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes a lithium-nickel composite oxide of a layered rock-salt type.

Positive electrode for secondary battery, and secondary battery

A positive electrode active material for a secondary battery includes a center part and a covering part. The center part includes a layered rock-salt lithium-nickel composite oxide. The covering part covers a surface of the center part and includes a boron compound. The positive electrode active material has a crystallite size of a (104) plane that is greater than or equal to 40.0 nm and less than or equal to 74.5 nm. The crystallite size is calculated by X-ray diffractometry and Scherrer equation. The positive electrode active material has a specific surface area that satisfies a condition represented by −0.0160×Z+1.72≤A≤−0.0324×Z+2.94 where Z is the crystallite size (nm), and A is the specific surface area (m/g). The specific surface area is measured by BET specific surface area measurement method.

Positive electrode active material for secondary battery, and secondary battery

A charging device is provided. The charging device switches to a (n+1)-th charging rate from a n-th charging rate when constant current charging is performed on a secondary battery at the n-th charging rate, at an SOC smaller than an SOC at which a voltage local minimum value appears when an experimental battery is charged at the n-th charging rate. The (n+1)-th charging rate is lower than the n-th charging rate, and n is a natural number.

Charging device, charging method, secondary battery, battery pack, electric vehicle, power storage device, electronic device, and power storage system using SOC

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Kyoto, Japan

Sho Takahashi