JP2008091036A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack formed by connecting two or more laminated batteries and having a small size, light weight, and reliable terminal taking out structure. <P>SOLUTION: The battery pack is formed by connecting two or more laminated batteries 1 in which the peripheral part of a laminate film of metallic foil and a resin film, which is a battery outer packaging material is fusion-bonded and an electrode terminal lead is taken out of a battery element. A rectangular tab terminal 5 for relay connecting the electrode terminal lead 2 to outside equipment is installed, and the tab terminal 5 has a folded-back edge part 51 formed by folding back and overlapping both side end edges; a spot-welding part 3 positioned on the inside of the folded-back edge part 51 to the electrode terminal lead 2; and a soldering part to a lead wire 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an assembled battery that is mainly used as a drive source for an electric assist bicycle or an electric tool and is formed by connecting a plurality of laminated batteries.

  In recent years, lithium ion batteries are often used as power sources for portable devices such as mobile phones and digital cameras due to demands for higher capacity and smaller size. In addition, a lithium ion battery having a high energy density and no memory effect is used as a power source for an electric assist bicycle or electric tool. In these portable devices, along with demands for miniaturization, lithium ion batteries are also required to be designed to be smaller and thinner.

  In recent years, a lithium ion battery using a laminate exterior material (a laminate material of a metal foil and a resin film) is used, and an assembled battery in which two or more of these laminate batteries are connected in series or in parallel has been used. There is an example of such a battery lead-out structure of the assembled battery as disclosed in Patent Document 1, however, as a terminal lead-out structure from a battery pack that has been reduced in size and thickness, a tab terminal formed by cutting a nickel material is connected to an external device. A soldered lead wire for connection is spot welded to an electrode terminal lead of a laminated battery.

  This conventional example will be described in detail with reference to the drawings. FIG. 4 is a plan view showing a terminal lead structure of the battery pack of the conventional example. After the lead wire 6 is soldered to the tab terminal 4 which is a rectangular flat plate, it is welded and connected to the electrode terminal lead 2 of the laminated battery 1 by the spot welded portion 3 indicated by x.

  FIG. 5 is a front view of the tab terminal 4 as viewed from the end side. That is, a rectangular flat plate having a certain thickness has been used for a tab terminal of a battery pack to which a conventional laminated battery is connected.

Japanese Patent No. 3591523

  4 and 5, when the lead wire diameter is increased in order to cope with an increase in current, the electrode terminal lead of the laminated battery is caused by stress due to the weight of the lead wire. There is a problem that the tab terminal breaks at the boundary portion between the welded portion and the soldered portion of the lead wire.

  In order to cope with this problem, it is conceivable to increase the thickness of the tab terminal. However, when the output is high, heat is generated due to a large current. It is not preferable. If the tab terminal is thick, stress is applied to the base of the electrode terminal lead of the laminated battery when a load to be bent is applied, which is not preferable. Furthermore, it becomes a factor of weight increase, and it becomes difficult to meet the demands for reducing the size and weight of the entire assembled battery.

  In this situation, an object of the present invention is to provide a battery pack having a small, lightweight and highly reliable terminal lead structure and connecting a plurality of laminated batteries.

  In order to solve the above problems, the assembled battery of the present invention is a laminated battery in which a metal foil as a battery outer packaging material and a peripheral part of a laminate film of a resin film are fusion-bonded and electrode terminal leads are drawn from the battery element. In the assembled battery in which a plurality of electrodes are connected, a rectangular tab terminal for relay connection of the electrode terminal lead to a lead wire for connection to an external device is disposed, and the tab terminal has edges on both sides. Folding edges overlapped so as to be in close contact with each other, a spot welded portion located inside the folded edge of the electrode terminal lead, and a soldered portion with the lead wire are formed. To do. Thus, the said subject is solved by using the tab terminal which gave the bending process of 180 degree | times folding to the edge part.

  Further, the assembled battery of the present invention is an assembled battery in which a plurality of laminated batteries in which the peripheral portions of a laminated film of a metal foil and a resin film as a battery exterior material are fused and joined and lead-out electrode terminals from the battery element are connected are connected. A rectangular tab terminal for relay connection of the electrode terminal lead to a lead wire for connection with an external device is provided, and the tab terminal is curved with rounded edges on both sides. A bent edge, a spot welded portion located inside the bent edge of the electrode terminal lead, and a soldered portion with the lead wire are formed. The above problem can also be solved by using a tab terminal in which a bent edge portion having R is formed at the edge.

  According to the present invention, the strength can be improved without increasing the thickness of the electrode terminal lead of the laminated battery and the tab terminal that relay-connects the lead wire. In addition, the tab terminal can be spot welded to the electrode terminal lead of the laminated battery without changing the welding conditions. Furthermore, since the strength can be improved without changing the thickness of the tab terminal, there is an effect that the weight of the assembled battery can be left unchanged.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  (Embodiment 1) FIG. 1 is a plan view showing a terminal lead-out structure of an assembled battery in Embodiment 1 of the present invention. FIG. 2 is a front view of the tab terminal in the present embodiment as viewed from the end side.

  Referring to FIG. 2, tab terminal 5 of the present embodiment has a shape obtained by adding a simple bending process by folding the edges of both sides of a rectangular flat plate by 180 degrees, and a folded edge 51 is formed. The tab terminal 5 used here is made of nickel having a length of 20 mm, a width of 5 mm, and a thickness of 0.15 mm, and the width of the folded edge portion 51 is 1 mm. As shown in FIG. 1, the lead wire 6 is soldered to the tab terminal 5, and then the electrode terminal lead 2 drawn out from the laminated battery 1 is spot welded 3 indicated by a cross mark. Weld. At this time, the electrode terminal lead 2 has a width of 13 mm and a thickness of 0.15 mm. FIG. 1 shows the terminal lead-out structure of the uppermost laminated battery 1 of a plurality of laminated batteries, and the connection portion with the electrode lead terminal of the lower laminated battery is omitted. Spot welding according to known techniques is used. As for the method of manufacturing the laminated battery 1, the peripheral part of the laminate film of the metal foil and the resin film is melted so as to enclose the battery element while pulling out the electrode lead terminal from the flat battery element by a known technique. Depending on how you wear.

  In this way, the bending process is applied to the edges on both sides of the tab terminal 5, so that the mechanical strength is improved and the welded portion of the electrode terminal lead 2 is used even though a thin tab terminal of 0.15 mm is used. The problem that the tab terminal 4 is broken or broken at the boundary between the lead wire 6 and the soldered portion of the lead wire 6 has been solved.

  (Embodiment 2) FIG. 3 is a front view of a tab terminal according to Embodiment 2 of the present invention as viewed from the end side. This tab terminal is produced by bending the edges of both sides of a rectangular flat plate. The bent edge 52 is rounded, that is, rounded and curved, and the end is closely attached to the upper surface of the tab terminal. It is fixed.

  Using this tab terminal as the tab terminal 5 in FIG. 1, the assembled battery of the first embodiment is obtained in the same manner as in the first embodiment. As a result, the problem that the tab terminal is cut or broken is solved.

  In addition, when bending the edge of the tab terminal with roundness, if the end is brought into close contact with the upper surface of the tab terminal and fixed, the mechanical strength is greatly increased, but the end is not brought into close contact with the upper surface and the edge is curved. Even bending in such a way increases mechanical strength due to plastic deformation or structural factors.

  As described above, in the present invention, a thin tab terminal is used in consideration of lightness, a stress balance with the electrode terminal lead or thermal conductivity, but the tab terminal is not used as a flat plate, The mechanical strength is ensured by bending the edges of both sides of the rectangular shape.

The top view which shows the terminal drawer structure of the assembled battery in Embodiment 1 of this invention. The front view which looked at the tab terminal in Embodiment 1 of this invention from the edge part side. The front view which looked at the tab terminal in Embodiment 2 of this invention from the edge part side. The top view which shows the terminal drawer structure of the assembled battery of a prior art example. The front view which looked at the conventional tab terminal from the edge part side.

Explanation of symbols

1 Laminated battery
2 Electrode terminal lead 3 Spot weld 4 Tab terminal 5 Tab terminal 6 Lead wire 51 Folding edge 52 Bending edge

Claims (2)

  In an assembled battery in which a plurality of laminated batteries are formed by fusion bonding the peripheral portions of a metal foil and a resin film laminate film as a battery exterior material and drawing out electrode terminal leads from battery elements, the electrode terminal leads are externally connected. A rectangular tab terminal for relay connection to a lead wire for connection to a device is disposed, and the tab terminal has a folded edge portion that is overlapped so that edges of both side edges are folded and adhered, and the electrode An assembled battery comprising a spot welded portion located inside the folded edge with the terminal lead and a soldered portion with the lead wire.   In an assembled battery in which a plurality of laminated batteries are connected by fusion bonding the peripheral portions of a metal foil and a resin film laminate film as a battery exterior material and drawing out electrode terminal leads from battery elements, the electrode terminal leads are externally connected. A rectangular tab terminal for relay connection to a lead wire for connection to a device is provided, the tab terminal has a bent edge portion with curved edges and rounded edges, and the electrode terminal An assembled battery comprising a spot welded portion located inside the bent edge portion with a lead and a soldered portion with the lead wire.

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