Sony Corporation

Aesc Japan Ltd.

Yosuke Kita

Satoshi Iwatsu

Hideya Takahashi

Aika Kimura

Kiyoshi Katayama

Tatuo Shimizu

In a lithium ion secondary battery element, a positive electrode and a negative electrode are overlapped on each other so that a positive electrode active material layer with a generally rectangular shape in the positive electrode and a negative electrode active material layer with a generally rectangular shape in the negative electrode are overlapped on each other substantially perfectly and a positive electrode active material non-applied part of the positive electrode and a negative electrode active material non-applied part of the negative electrode are positioned on opposing sides of the rectangle. A border part between the negative electrode active material applied part and the negative electrode active material non-applied part is positioned closer to a peripheral side of a negative electrode current collector than a peripheral part of a positive electrode current collector. A border part between a negative electrode active material layer flat part and a negative electrode active material layer thin part is positioned closer to a central side of the negative electrode current collector than the peripheral part of the positive electrode current collector. The negative electrode active material layer thin part has a density that is equal to or smaller than that of the negative electrode active material layer flat part.

Lithium ion secondary battery element including negative electrode with negative electrode active material layer tapered part having smaller density than negative electrode active material layer flat part

A spirally coiled electrode assembly has positive and negative electrodes each including a web-like collector coated with an active material on opposite surfaces thereof, and separators disposed between the positive and negative electrodes. A plurality of rectangular leads extend from opposite sides of the web-like collectors in directions perpendicular to a direction in which the positive and negative electrodes and the separators are wound. Positive and negative terminals are connected to the rectangular leads extending from the respective opposite sides of the web-like collectors. The spirally coiled electrode assembly, the rectangular leads, and the positive and negative terminals are housed in a cylindrical casing whose opposite ends are closed by respective caps. The positive and negative terminals are fixed to the caps, respectively.

High capacity secondary battery of jelly roll type

Growing community of inventors

Kanagawa, Japan

Yosuke Kita