Gs Yuasa International Ltd.

Ryosuke Shimokawa

Takeshi Sasaki

Shota Ito

Tomonori Kako

Akihiko Miyazaki

Taro Yamafuku

Masaki Masuda

Kazuki Kawaguchi

Fumiya Nakano

Kenta Ogi

Kei Kumabayashi

Takeshi Saski

An aspect of the present invention is an energy storage device including an electrode assembly that has a negative electrode and a positive electrode, where the negative electrode contains a negative electrode substrate and a negative active material, and has a negative active material layer disposed in an unpressed shape along at least one surface of the negative electrode substrate, the negative active material includes solid graphite particles as a main component, and the solid graphite particles have an aspect ratio of 1 or more and 5 or less.

Energy storage device and method for manufacturing energy storage device

An energy storage device is provided that has improved power performance at low temperature. In the present embodiment, an energy storage device is provided that includes an electrode having an active material layer, the active material layer contains at least active material particles, the particles contained in the active material layer gives a volume-based particle size frequency distribution that has a first peak and a second peak appearing in a particle size larger than a particle size of the first peak, and particles having particle sizes equal to or smaller than a particle size Dx have a volume proportion of 49% or more and 62% or less in a volume of whole particles contained in the active material layer, with the particle size Dx defined as a particle size at a local minimum frequency between the first peak and the second peak in the particle size frequency distribution.

An energy storage device having sufficient energy density and sufficient power is provided. In this embodiment, an energy storage device that includes a negative electrode containing an active material layer including an active material is provided. The active material layer includes particulate graphite as the active material. A particle diameter frequency distribution of the graphite includes a first peak and a second peak which appears in a region where a particle diameter is larger than a particle diameter of the first peak, the particle diameter of the first peak is equal to or less than 10 &#x3bc;m and the particle diameter of the second peak is more than 10 &#x3bc;m. The active material layer further includes a particulate high hardness active material which has higher hardness than the graphite.

Energy storage device

Growing community of inventors

Kyoto, Japan

Ryosuke Shimokawa