Gs Yuasa International Ltd.

Shota Ito

Takeshi Sasaki

Tomonori Kako

Kazuki Kawaguchi

Ryosuke Shimokawa

Akihiko Miyazaki

Sumio Mori

Taro Yamafuku

Kenta Nakai

Jun Oyama

Masaki Masuda

Fumiya Nakano

Kenta Ogi

Kei Kumabayashi

Takeshi Saski

Taisei Sekiguchi

One aspect of the present invention is an energy storage device including a positive electrode containing: first positive active material particles containing a metal element capable of forming a conductive metal oxide; and second positive active material particles not containing the metal element, in which the first positive active material particles include a nickel-cobalt-manganese-containing lithium-transition metal composite oxide containing lithium, nickel, cobalt, and manganese as constituent elements, and the first positive active material particles are larger in median diameter than the second positive active material particles.

Energy storage device

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 includes: a positive electrode plate containing a positive composite layer including a positive active material capable of occluding and releasing a lithium ion; and a negative electrode plate containing a negative composite layer including a negative active material capable of occluding and releasing a lithium ion. A peak pore diameter Rp of the positive composite layer in a pore distribution measured by a mercury penetration method is 0.5 &#x3bc;m or less, and a peak pore diameter Rn of the negative composite layer in a pore distribution measured by a mercury penetration method is 0.5 &#x3bc;m or less. A ratio Rp/Rn of the peak pore diameter of the positive composite layer to the peak pore diameter of the negative composite layer is 0.60 or more and 1.70 or less.

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 includes a positive electrode having a positive active material layer containing an active material in the form of particles. The positive active material layer contains primary particles of the active material and secondary particles formed by aggregation of a plurality of primary particles. The proportion of primary particles relative to all particles of the active material in the positive active material layer is 5% or more and 40% or less. An method for producing an energy storage device includes preparing a positive electrode having a positive active material layer by forming a positive active material layer from a composite containing at least secondary particles of an active material, and assembling an energy storage device using the prepared positive electrode. In the preparation of the positive electrode, the positive active material layer is pressed to deagglomerate some of the secondary particles into primary particles, and the proportion of primary particles relative to all particles of the active material in the positive active material layer is adjusted to 5% or more and 40% or less.

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.

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Kyoto, Japan

Shota Ito