Secondary battery and method for producing the same

摘要

A secondary battery has: an electrode group which includes sheet-form positive and negative electrode plates each including a metallic foil having an active material applied onto both sides of the metallic foil, and a separator disposed between the positive and negative electrode plates, wherein the positive and negative electrode plates and the separator are spirally wound together around a winding core into a flattened shape, wherein the electrode group has, at the both ends thereof as viewed in the winding core direction, respectively formed metallic foil exposed portions of the positive and negative electrode plates onto which the active material is not applied; a battery container which contains the electrode group therein, wherein the battery container has a battery casing and a battery cap; and positive and negative external terminals electrically connected to the metallic foil exposed portions of the positive and negative electrode plates, respectively. Winding end portions in the metallic foil exposed portions of the positive and negative electrode plates are arranged opposite to the inner surface of the battery container through respective conducting members.

主权项

1. A secondary battery comprising:
an electrode group including sheet-form positive and negative electrode plates each including a metallic foil having an active material applied onto both sides of the metallic foil, and a separator disposed between the positive and negative electrode plates, the positive and negative electrode plates and the separator being spirally wound together around a winding core into a flattened shape, the electrode group having, at the both ends thereof as viewed in the winding core direction, respectively formed metallic foil exposed portions of the positive and negative electrode plates onto which the active material is not applied; a battery container which contains the electrode group therein, the battery container having a battery casing with opposing wide and narrow surfaces and a battery cap; and positive and negative external terminals electrically connected to the metallic foil exposed portions of the positive and negative electrode plates, respectively, wherein winding end portions in the metallic foil exposed portions of the positive and negative electrode plates are arranged opposite to the inner surface of the battery container through respective conducting members; wherein the metallic foil exposed portions of the positive and negative electrode plates are stacked in the thickness wise direction of the battery casing to form respective stacked structures, wherein the stacked structures of the positive and negative electrode plates are respectively bonded to positive and negative connecting plates which electrically connect the respective metallic foil exposed portions to the positive and negative external terminals, respectively, wherein the positive and negative connecting plates each have a respective joint leaf provided so as to face a wide surface of the battery casing, and respective connecting members which connect the joint leaves to the positive and negative external terminals, respectively, each connecting member extending to the battery cap along a narrow surface of the battery casing, and wherein ultrasonic bonding sites are defined on each joint leaf and the joint leaves are respectively ultrasonically welded to the winding end portions of the positive and negative electrode plates to thereby fix the winding end portions in a direction towards the battery cap; and wherein each connecting plate has a base portion extending along the inner surface of the battery cap, a side portion having a broad surface which extends curved from the base portion at a substantially right angle and to a lower portion of the electrode group such that the broad surface extends along a narrow sidewall of the battery casing toward a bottom, and the joint leaf extends from a lower half portion of the side portion and is curved toward the electrode group curved along the wide surface of the battery casing at a substantially right angle, the joint leaf and side portion together form a unified structure having an L-shaped cross-section and have high strength and high rigidity.