PRISMATIC CELL AND PRODUCTION METHOD FOR THE SAME

• US 20110223454A1
• Filed: 02/16/2011
• Published: 09/15/2011
• Est. Priority Date: 03/15/2010
• Status: Active Grant

• Current Assignee: Vehicle Energy Japan, Inc. (Nissan Motor Co., Ltd.)
• Original Assignee: Hitachi Automotive Systems Limited (Hitachi, Ltd.)
• Inventors: Urano, Kazuaki, Sekine, Kiyoyuki, Watashi, Suguru, Matsuoka, Yasuhiro, Kajiwara, Kouichi, Hirano, Fujio
• Granted Patent: US 8,986,874 B2
• Time in Patent Office: Days
• US Class Current: 429/94
• CPC Class Codes: H01M 10/0431 Cells with wound or folded electrodes H01M10/045 takes precedence
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/0587 of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
• CPC Class Codes: H01M 50/15 for prismatic or rectangular cells H01M50/153 takes precedence
• CPC Class Codes: H01M 50/538 Connection of several leads or tabs of wound or folded electrode stacks
• CPC Class Codes: H01M 50/55 on the same side of the cell
• CPC Class Codes: H01M 50/553 Terminals adapted for prismatic, pouch or rectangular cells
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 29/49108 Electric battery cell making
• CPC Class Codes: Y10T 29/49112 including laminating of indefinite length material

Abstract

A wound electrode body is fabricated by laminating and winding positive and negative electrode sheets together with a separator therebetween for insulation. On both positive and negative electrode side ends of the wound electrode body, laminates of current-collecting foil layered portions of the electrode sheets are bent or folded f toward the outer peripheral side to be separated into two. The separated laminates and forked connector leaves are overlapped and clamped between an ultrasonic chip and an anvil. Then, they are welded. The forked connector leaves are arranged such that no opposing forked connector leaf is present in the direction of a line normal to the forked connector leaf, so that the anvil does not have to be cantilevered. This allows welding by using the ultrasonic chip and the anvil without interfering with the collector rs. As a result, the quality of welding is improved.

Claims

1. A prismatic cell comprising:

a wound electrode body that includes

a positive electrode sheet having a metal foil on which a positive active material has been applied,

a negative electrode sheet having a metal foil on which a negative active material has been applied, and

separators intervening between the positive and negative electrode sheets,

wherein current-collecting foil portions on which no positive or negative active materials have been applied are provided on both ends of the wound electrode body as positive and negative electrode connection parts, respectively, and the positive electrode sheet, the negative electrode sheet and the separators are wound in a flat or thin shape;

a container having a flat shape in cross-section, in which the wound electrode body is accommodated, the container having an opening;

a lid that seals the opening of the container;

positive and negative external terminals provided on the lid;

a positive electrode current-collecting collector member that electrically connects the positive electrode connection part of the positive electrode sheet to the positive external terminal, the positive electrode current-collecting collector member having forked connector leaves with connection surfaces in contact with front and back surfaces of the positive electrode connection part; and

a negative electrode current-collecting collector member that electrically connects the negative electrode connection part of the negative electrode sheet to the negative external terminal, the negative electrode current-collecting collector member having forked connector leaves with connection surfaces in contact with front and back surfaces of the negative electrode connection part, wherein

on both ends of the wound electrode body in the direction of winding axis, a laminate of the positive electrode connection part and a laminate of the negative electrode connection part are separated into two laminates, respectively, by pushing the innermost periphery part outwardly in the direction of the flat container, respectively, and wherein

the connection surfaces of the forked connector leaves of the positive and negative electrode collector members, respectively, are welded to the respective outer peripheral surfaces of the separated laminates.

2. A prismatic cell according to claim 1, wherein

both the ends of the wound electrode body in the direction of the winding axis are opposite to narrower side surfaces of the ends of the container in the direction of the winding axis;

the respective forked connector leaves of the positive and negative electrode collector members extend toward the bottom of the container along the narrower side surfaces of the container; and

the two separated laminates are inclined to each other so as to expand toward the narrower sides and the connection surfaces of the forked connector leaves of the positive and negative electrode connection parts are welded to the respective outer peripheral surfaces of the inclined two separated laminates on both the ends of the wound electrode body.

3. A prismatic cell according to claim 1, wherein

the pair of connection surfaces of the forked connector leaves are formed nonparallel to each other such that a gap therebetween is decreasing from the narrower side surface toward an inside of the container so that the pair of the connection surfaces of the forked connector leaves form an angle that correspond to an angle formed between the outer peripheral surfaces of the two separated laminates.

4. A prismatic cell according to claim 1, wherein

the forked connector leaves are arranged as being tilted at an angle therebetween such that a normal line to any one of the pair of the connection surfaces on the respective inner sides of the forked connector leaves does not pass the other of the connection surface.

5. A method for producing a prismatic cell according to claim 1, which method comprising the steps of:

fabricating the lid assembly by connecting the positive and negative external terminals to the positive and negative electrode collector members, respectively;

fabricating the wound electrode body by winding the positive electrode sheet, the negative electrode sheet and the separators intervening between the positive and negative electrode sheets into a flat shape in cross-section;

integrating the lid assembly with the wound electrode body;

separating the two laminates by outwardly pushing the laminates of the positive and negative electrode connection parts, where the positive and negative electrode foils have each no active material applied thereon, on both ends of the wound electrode body in the direction of winding axis; and

connecting the two separated laminates to the forked connector leaves of the positive and negative electrode collector members, respectively.

6. A method according to claim 5, wherein

the step of connecting the two separated laminates further comprises the steps of:

arranging an ultrasonic chip and an anvil along a normal to the connection surfaces of one of the forked connector leaves, respectively;

disposing one of the anvil or the ultrasonic chip so as to abut against the inner peripheral surface of one of the two separated laminates and also disposing the other of the anvil or the ultrasonic chip so as to abut against the outer peripheral surface of one of the connector leaves of the forked connector leaves, respectively, to clamp the two separated laminates and the connection surfaces by the ultrasonic chip and the anvil; and

applying welding energy to the ultrasonic chip to weld the separated laminates to the connection surfaces.