Matsushita Electric Industrial Co., Ltd.

Yoshihiro Boki

Masaharu Miyahisa

Masumi Katsumoto

Hideki Kasahara

Masahiko Kato

Satoshi Yoneyama

Hideyuki Kumakiri

A battery having a coiled electrode plate assembly housed in a case that efficiently utilizes the space available in portable electronic appliances is provided. The battery casehas a head portionhaving a circular cross section and a body portionhaving a substantially square cross section, one side of which is equal to or longer than the diameter of the circular cross section of the head portion.

Battery and method for manufacturing the same

After accommodating an electrode group in a battery case having a substantially square transverse cross section, making an opening head of the battery case into a cylindrical shape through compression molding, an annular groove is formed by pressing a groove-forming roller sideways against a side surface of the opening head while rotating the battery case with a pressing force being kept applied to the battery case in an axial direction from the opening portion side, or alternatively pressing the groove-forming roller against the opening head from the side surface thereof and concurrently displacing the groove-forming roller in a direction toward the opening portion of the battery case while rotating the battery case. After having an annular supporting portion that bulges inward of the battery case support an opening-sealing member, the opening-sealing member is fixed through caulking by bending the opening end portion of the battery case inward, whereby a battery is manufactured.

The present invention relates to a battery using a case of which the section of the lower part containing an electric element is square or hexagonal and the section of the upper part containing a sealing plate is circular or elliptic. By virtue of the shape of the lower part the space efficiency of the battery pack is enhanced and by virtue of the shape of the upper part the productivity of the battery is improved. Further, preferably, the corners of the lower part of the case are rounded or chamferred, whereby the temperature rise in the battery pack is suppressed.

Battery, a process for producing the battery, a process for producing a battery case, and a battery pack

A battery case ( ), substantially square in cross section, has four lateral walls ( ) each of which is gradually arc-shaped to expand outwardly with a radius of curvature R The cross section is adapted to satisfy equation R /r&equals;4 to 20, where r is the distance between a midpoint (C ) of each lateral wall ( ) and the center point (C ) in the cross section of the battery case ( ) and R is the radius of curvature. In addition, the battery case ( ) is rounded at each corner with a radius of curvature of R and has a cross section that satisfies equation R /r&equals;0.3 to 0.8, where r is the distance between the midpoint (C ) of each lateral wall ( ) and the center point (C ) in the cross section of the battery case ( ) and R is the radius of curvature of each corner.

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Kanagawa, Japan

Yoshihiro Boki