WO2007063877A1

WO2007063877A1 - Method for producing electrical device assembly

Info

Publication number: WO2007063877A1
Application number: PCT/JP2006/323780
Authority: WO
Inventors: Tadashi Shimamori
Original assignee: Nec Corporation; Fuji Jukogyo Kabushiki Kaisha
Priority date: 2005-12-01
Filing date: 2006-11-29
Publication date: 2007-06-07
Also published as: JPWO2007063877A1; JP2012109275A; JP5438154B2; JP5046956B2

Abstract

A battery (50) comprises a plurality of unit cells (20A-20D) connected in series. An electrode tab (25a) from the unit cell (20A) is joined to the upper surface of a bus bar (41), while an electrode tab (25b) from the unit cell (20B) is joined to a lateral surface of the bus bar. As the first welding step, a bus bar (41) is joined to one electrode tab (25a) in a state where the unit cells (20) are separate from each other. Then, as the second welding step, an electrode tab (25b) is joined to the lateral surface of the bus bar in a state where the unit cells each having a bus bar are stacked.

Description

Specification

Method for manufacturing electrical device assembly

Technical field

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing an electrical device assembly in which a plurality of electrical devices (for example, batteries, capacitors, etc.) that store and output electrical energy are assembled, and more particularly, to a method for electrically connecting electrical devices. .

Background art

Conventionally, as a type of thin battery, a film-covered battery in which a battery element is housed together with an electrolytic solution in a packaging bag having a laminated film or the like is known. For example, when this type of battery is used as a drive source for an electric vehicle, a plurality of film-clad batteries may be used. A battery in which a plurality of batteries are assembled in this way is also called an “assembled battery”, and each film-covered battery is also called a “battery cell”.

FIG. 1 is a perspective view showing a configuration of an assembled battery disclosed in Japanese Patent Application Laid-Open No. 2004-31225. As shown in FIG. 1, the assembled battery 150A has a configuration in which four battery cells C1 to C4 are stacked, and the battery cells are connected in parallel. Sheet-like electrode tabs (lead terminals) 125 are drawn out from both ends of each battery cell. Taking the relationship between two battery cells Cl and C2 adjacent to each other in the stacking direction as an example, the electrode tab 125 of one battery cell C1 and the electrode tab 125 of the other battery cell C2 are made of a conductive material. Are connected to each other via bus bar 141.

Disclosure of the invention

[0004] By the way, Japanese Patent Application Laid-Open No. 2004-31225 describes the use of welding or the like to connect the bus bar 141 and the electrode tab 125, but details thereof are described. There is not enough description. Therefore, for example, in the configuration shown in FIG. 2, when trying to weld the bus bar and the electrode tab, the following problems may occur.

[0005] In the assembled battery 150B of FIG. 2, four battery cells C1 to C4 are connected in series.

Specifically, the electrode tab 125 of the battery cell C1 and the electrode tab 125 of the battery cell C2 are overlapped with each other, and the overlapping portion is welded to the side surface of the bus bar 141. Has been. Although not shown, battery cells C2 and C3 are electrically connected in the same manner. The welding may be laser welding or the like, for example, irradiation with a laser beam from the direction shown by arrow B.

[0006] In order to perform welding joint by such a method, however, it is necessary to position and hold the two electrode tabs 125 and the bus bar 141 with each other. It was a complicated process. Further, in order to perform such holding, a jig (holding jig) having a relatively complicated structure is required.

[0007] As described above, the power for explaining the manufacturing problems related to the conventional configuration using the battery as an example. Such a problem can occur not only in the battery but also in other electric devices (for example, a capacitor).

[0008] The present invention has been made in view of the above-mentioned problems, and its object is to prevent poor welding between the electrode tab and the bus bar and to simplify the pressing jig used during welding. An object of the present invention is to provide a method of manufacturing an electric device assembly that is advantageous for achieving the above.

[0009] The method for manufacturing an electrical device assembly of the present invention for realizing the above-described object includes electrically connecting sheet-like electrode tabs drawn from the electrical device cartridges, so that a plurality of the electrical devices are electrically connected. A method of manufacturing an assembly of electrical devices in which devices are electrically connected in series and Z or in parallel, wherein a bus bar made of a conductive material is joined to one of the electrode tabs from which the electrical device force is drawn. A first welding step, a step of superimposing a predetermined number of the electric devices in which the bus bar is joined to the one electrode tab, and one electric device of the predetermined number of the superposed electric devices. When the bus bar joined to the electrode tab of the vice and the bus bar of another electrical device adjacent to the one electrical device are joined, the other electrode tab on the side And a second welding process for joining the joints.

[0010] In the electrical device assembly manufactured according to the present invention, one electrode tab and the other electrode tab are electrically connected to each other by being connected to the bus bar. In manufacturing the electrical device assembly having such a configuration, according to the present invention, as a first welding process, first, a bus bar and one electrode tab are joined. Next, as a second welding process, the bus bar and the other electrode tab are joined. First and second welding In each step, only one electrode tab and bus bar and the other electrode tab and bus bar need to be positioned between the two members. In other words, there is no need to position the three members (two electrode tabs and one nos bar) that are still joined to each other as in the conventional welding process. For this reason, the occurrence of poor welding due to inaccurate positioning of the three members is suppressed. In addition, the reliability of the formed weld will be improved. Furthermore, according to the present invention, since it is not necessary to position the three members that are not joined to each other, the pressing jig used during welding can be simplified.

[0011] According to the present invention, as described above, poor welding between the electrode tab and the bus bar hardly occurs, and it is also possible to simplify the holding jig used during welding. Brief Description of Drawings

FIG. 1 is a perspective view showing a configuration of a conventional assembled battery.

FIG. 2 is a diagram for explaining problems that may occur when welding is performed by a conventional method.

FIG. 3 is a plan view showing the configuration of the assembled battery according to the first embodiment.

4 is a perspective view showing a battery cell used in the assembled battery of FIG. 3 in a single state.

FIG. 5 is a perspective view for explaining an example of a form of a welded portion.

FIG. 6 is a view for explaining an embodiment of the production method of the present invention.

FIG. 7 is a plan view showing another configuration example of the bus bar.

FIG. 8 is a plan view showing an example of a jig suitable for a hollow bus bar.

FIG. 9 is a plan view showing a configuration of a battery pack according to a second embodiment.

FIG. 10 is a diagram for explaining another example of the production method of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

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

(First embodiment)

FIG. 3 is a diagram showing a configuration of an assembled battery which is an embodiment of the electrical device assembly manufactured according to the present invention. FIG. 4 is a perspective view showing a battery cell used in the assembled battery of FIG. 3 in a single state.

[0014] As shown in FIG. 3, the assembled battery of the present embodiment is an assembly of battery cells 20A to 20D. It is a four-tiered structure. Each battery cell is electrically connected in series so that the voltage corresponding to the number of battery cells is output.

[0015] Battery cells 20A to 20D (hereinafter also simply referred to as battery cells 20) have the same structure, and are shown in FIG. 4 in detail as film-wrapped batteries having a frame. . The battery cell 20 includes a thin battery element 22 that outputs a predetermined electromotive force (eg, 3.6 V) in an enclosed space formed by the exterior film 24 together with an electrolyte. The exterior film 24 has a structure in which two films are laminated, and a sealing portion 23 in which the films are heat-sealed is formed on the outer peripheral portion of the exterior film 24 !. A positive electrode tab 25a and a negative electrode tab 25b are drawn out from two sides on the short side of the rectangular exterior film 24.

[0016] The battery element 22 has a plurality of sheet-like positive electrodes with a positive electrode active material coated on the surface and sheet-like negative electrodes with a negative electrode active material coated on the surface, alternately stacked via separators. The thickness is, for example, about several mm.

[0017] The electrode tabs 25a and 25b (hereinafter also simply referred to as electrode tabs 25) are sheet-like conductive members having a thickness of, for example, 50 μm to 300 μm. The material of the electrode tab 25a for the positive electrode is, for example, aluminum or an aluminum alloy. The material of the electrode tab 25b for the negative electrode is, for example, copper or an alloy.

The frame body 28 is composed of a pair of members provided so as to sandwich the sealing portion 23 of the exterior film 24. However, the frame body is not limited to the shape shown in FIG. 4 and can be variously modified. For example, the frame body may have a shape like a case that covers the entire exterior film 24.

[0019] Referring again to FIG. The bus bar 41 is a rod-like member having a rectangular cross section that also has a conductive material force such as copper. In the present embodiment, one bus bar 41 is attached to each electrical connection between the battery cells 20. The voltage for each battery cell 20 can be detected by using each bus bar 41 attached in this way as a terminal for voltage extraction.

As shown in FIG. 3, the assembled battery 50 of the present embodiment has one surface of the electrode tab 25a drawn from one battery cell (for example, 20A) joined to the upper surface 41u of the bus bar 41, Electrode tab 25b of other battery cell (eg 20B) is joined to side 41s of bus bar 41 It is. For this joining, for example, laser welding can be used. In this embodiment, the electrode tab 25a and the upper surface of the bus bar are joined by the welded portion 37 formed by laser welding, and the electrode tab 25b and the side surface of the busbar are joined by the welded portion 38 also formed by laser welding. Yes. With such a configuration, the electrode tabs 25a and 25b are electrically connected via the bus bar 41.

[0021] Note that the welded portion 37 may be a plurality of spot-shaped welded portions 37A as shown in FIG. 5 (a), for example. Alternatively, the welded portion 37 may be a linear welded portion 37B as shown in FIG. The same applies to the weld 38. Further, as shown in FIG. 5, the bus bar 41 may be formed longer than the width of the electrode tab 25.

Next, a method for manufacturing the assembled battery 50 of the present embodiment having the above configuration will be described with reference to FIG. FIG. 6 is a view for explaining the manufacturing method of the present embodiment, and shows four steps from FIG. 6 (a) to FIG. 6 (d)! /.

First, as shown in FIG. 6 (a), a predetermined number of battery cells 20 prepared by a conventionally known method are prepared. In the battery cell 20, one electrode tab 25b is formed longer than the other electrode tab 25a. This is because the electrode tab 25b is bent at the tip end side and connected to the bus bar side surface, as will be described later. In order to realize this, it is necessary to make the electrode tab 25a relatively longer than the electrode tab 25a. Because there is.

Next, as shown in FIG. 6 (b), the tip side of the electrode tab 25b is brought into the shape of the bus bar 41 and bent, for example, at a right angle. Further, laser welding is performed on the other electrode tab 25a, thereby joining the electrode tab 25a and the upper surface of the bus bar (first welding step). Through this process, one electrode tab 25b is bent, and a predetermined number of battery cells 20 in which the bus bar 41 is welded to the other electrode tab 25a are formed.

[0025] This first welding process is performed in a state where one electrode tab 25a and bus bar 41 are positioned and in close contact with each other. The laser beam B1 may be irradiated, for example, perpendicularly to the electrode tab 25a (perpendicular to the upper surface of the bus bar), thereby forming a welded portion 37 extending in the vertical direction.

[0026] In such a welding process, welding defects are less likely to occur compared to a welding process (see Fig. 2) in which three members such as two electrode tabs and one bus bar must be positioned. This is advantageous. In this welding process, the electrode tab 25a drawn straight (the electrode tab 25a in an initial state after bending is performed) and the bus bar are joined. Therefore, the jig for pressing the electrode tab 25a against the upper surface of the bus bar at the time of welding can be simply configured. On the other hand, as shown in Fig. 2, when joining the front end side of the electrode tab subjected to the bending force and the bus bar, a jig having a relatively complicated structure may be required.

Next, as shown in FIG. 6 (c), the battery cells 20A to 20D with bus bars manufactured up to the above-described steps are overlapped with their directions alternately reversed. That is, the two battery cells 20A and 20B are overlapped so that the bus bar 41 of one battery cell 20A and one electrode tab 25b of the battery cell 20B adjacent to the battery cell 20A face each other. The same applies to the other battery cells 20C and 20D.

[0028] When the four battery cells are overlapped in this way, laser welding is sequentially performed for each electrical connection portion as shown in Fig. 6 (d) (second welding process). ). At this stage, since the electrode tab 25a and the bus bar 41 are already joined, it is only necessary to position the one electrode tab 25b and the bus bar 41 relative to each other. After positioning, the welded portion 38 extending in the horizontal direction is formed by, for example, irradiating the laser beam B2 in the horizontal direction (perpendicular to the side surface of the bus bar). As a result, the electrode tab 25b and the bus bar 41 are joined, and the electrode tabs 25a and 25b are interconnected via the bus bar 41.

[0029] Thereafter, the final assembled battery 50 is completed through several conventionally known processes such as a screwing process for finally fixing the battery cells.

[0030] According to the manufacturing method of the present embodiment described above, in the configuration in which the two electrode tabs 25a and 25b are welded to the bus bar 41, the step of joining one electrode tab 25a and the bus bar 41; Since the process of joining the other electrode tab 25b and the bus bar 41 is a separate welding process, the following advantages are obtained. In other words, in the conventional method shown in FIG. 2, it was necessary to position and hold a total of three members, two electrode tabs and a bus bar. On the other hand, in the configuration of the present embodiment, only the positioning between two members such as one electrode tab 25 and bus bar 41 and the other electrode tab 25b and bus bar 41 is performed in each welding process. For example, it is not necessary to position the three members that are not joined to each other. Therefore, poor welding due to inaccurate positioning of the three members is less likely to occur, and the reliability of the formed weld is improved.

[0031] Although one embodiment of the present invention has been described above, the present invention can be variously modified in addition to the above. For example, in the manufacturing procedure described above, the force that the electrode tab 25b has already been bent in the process of FIG. 6 (b) may be performed in the process of FIG. 6 (d). Good. In other words, after overlapping a plurality of battery cells, the tip side of the electrode tab 25b may be bent along the side of the bus bar.

[0032] The shape of the bus bar 41 is not limited to the above. For example, a hollow bus bar 42 as shown in FIG. When the hollow bus bar 42 is used as described above, the bus bar 42 can be satisfactorily held by using a jig 80 having a tapered tip insertion portion 81 as shown in FIG. By bringing the pair of jigs 80 close to each other, the distal end portion of the insertion portion 81 enters the hollow portion of the bus bar 42, and the bus bar 42 is held by engaging there.

[0033] In the case of the hollow bus bar 42, it is also possible to send cooling air to the inside. For example, if the cooling air is sent to the inside of the bus bar 42 when used as an assembled battery, the temperature rise of the electrode tabs 25a and 25b can be suppressed. Alternatively, cooling air may be sent when welding the electrode tabs 25a, 25b and the bus bar 42.

[0034] Alternatively, the bus bar may be a bus bar 43 having a C-shaped cross section as shown in FIG. Force due to the force with which the opening of the C-shaped cross section is directed in any direction As shown in Fig. 7 (b), when the bus bar 43 is arranged so that the opening faces the electrode tab 25b, cooling is performed inside the bus bar. It is also possible to pass the wind. As a result, the same effect as that of the hollow nose bar 42 can be obtained in that the cooling air is sent.

The bus bar may be a bus bar 44 having an L-shaped cross section as shown in FIG. 7 (c).

Each of the three bus bars 42, 43, 44 shown in Fig. 7 has upper surfaces 42u, 43u, 44u to which the electrode tab 25a is joined, and 佃 J surfaces 42s, 43s, 44s to which the electrode tab 25b is joined. It's common in terms of!

[0036] By the way, the case where the solid bus bar 41 as shown in FIG. 3 is used and the case shown in FIG. Compared to the case where such a hollow bus bar 42 is used, the use of the hollow bus bar 42 is preferable in that efficient welding can be performed. In other words, in the solid bus bar 41, the heat generated by the laser beam irradiation easily escapes into the bus bar 41, whereas in the hollow bus bar 42, it is difficult for such heat to propagate, so the energy of the laser beam is reduced. This is because it can be used more efficiently. The same effect can be obtained with the bus bars 43 and 44, though depending on the thickness of the part irradiated with the laser beam.

(Second embodiment)

Next, another configuration to which the manufacturing method of the present invention can be applied will be described with reference to FIG. In the embodiment described above, the electrode tab of one battery cell and the electrode tab of the other battery cell adjacent to the battery cell are not in contact with each other. However, the present invention is not limited thereto. Like the assembled battery 51 of FIG. 9, the force may overlap the tip side of the electrode tab 25a and the tip side of the electrode tab 25b. In FIG. 9, as an example, the force that the positive electrode tab 25a of the two electrode tabs 25a and 25b is folded relatively inward so as to come into contact with the side surface 41s of the bus bar 41 is the opposite. May be. The electrode tab 25a is joined to the upper surface of the bus bar by the welded portion 37, and the electrode tabs 25a and 25b are joined to the side surface of the bus bar by the welded portion 38 ′.

Next, a method for manufacturing the assembled battery 51 will be described with reference to FIG. Note that a part of the description of the same steps as the manufacturing method described with reference to FIG. 6 is omitted.

First, as shown in FIG. 10 (a), a predetermined number of battery cells 20 ′ are prepared by a conventionally known method. In the battery cell 20 ′ of FIG. 10, the electrode tabs 25a and 25b have substantially the same length.

Next, as shown in FIG. 10B, the electrode tab 25b is bent and the laser beam B1 is irradiated to weld the electrode tab 25a and the bus bar 41 (first welding step). This welding is performed in a state where a margin is provided on the tip side of the electrode tab 25a, that is, in a state where some surplus portion is left on the tip side. This surplus portion is bent along the side surface of the bus bar 41. This bending process may be carried out before and after welding!

Next, the battery cells with bus bars obtained in the step of FIG. 10 (b) are overlapped as shown in FIG. 10 (c), and the front end side of the bent electrode tab 25b faces the side surface of the bus bar. Or Apply laser beam B2 while pressing (second welding process). As a result, a welded portion 38 ′ (see FIG. 9) is formed, and the overlapping portion of the electrode tabs is joined to the side surface of the bus bar.

[0041] In the manufacturing method of the present embodiment as described above, the welding of the electrode tab 25a and the bus bar 41 and the welding of the electrode tab 25b and the bus bar 41 are performed in separate steps. It is possible to obtain the same effect as that of the embodiment.

[0042] In the step of Fig. 10 (c), the welding method of the present embodiment and Fig. 2 are shown in that the tip side of the two electrode tabs 25a, 25b is pressed against the side surface 4 Is of the bus bar. The force that seems to be in common with the other welding methods is different in the following points. That is, in the method of FIG. 2, the two electrode tabs 125 and the bus bar 141 are not yet joined to each other at the time of welding. On the other hand, in the method of the present embodiment, the bus bar 41 and the electrode tab 25a are already welded when welding is performed. Therefore, this process is substantially different from the method shown in FIG. 2 in that only the positioning of the bus bar 41 and the electrode tab 25b has to be performed.

In the above description, laser welding has been described as an example. However, the present invention is not limited thereto, and ultrasonic welding, resistance welding, spot welding, thermal welding, laser welding, electron beam welding, or the like is used. You may do. The irradiation direction of the laser beams Bl and B2 is not limited to the direction perpendicular to each surface of the bus bar, but may be a predetermined angle. In the above description, the positive electrode tab 25a and the bus bar are joined first, and then the negative electrode tab 25b and the bus bar are joined! /, But this order is The reverse is also possible.

The “electric device” in the present specification corresponds to the battery cell 20 in the above embodiment. The types of battery cells 20 are not particularly limited, such as lithium ion secondary batteries, nickel metal hydride batteries, nickel-powered nickel batteries, lithium metal primary Z secondary batteries, or lithium polymer batteries. It is not limited. For example, instead of the exterior film 24 (see FIG. 5), a battery cell in which the battery element 22 is sealed with a rigid can or the like can be used. Furthermore, the “electric device” is not limited to a battery, and may function as a capacitor, for example.

Claims

The scope of the claims

[1] A method of manufacturing an electrical device assembly in which a plurality of electrical devices are electrically connected in series and Z or in parallel by electrically connecting sheet-like electrode tabs drawn from each electrical device Because

A first welding step of joining a bus bar made of a conductive material cover to one of the electrode tabs drawn from the electrical device;

A step of superposing a predetermined number of the electric devices in a state where the bus bar is bonded to the one electrode tab;

The bus bar joined to the electrode tab of one electrical device out of the predetermined number of the electrical devices superimposed, and the nos bar of another electrical device adjacent to the one electrical device are joined. A method of manufacturing an electrical device assembly, comprising: a second welding step for joining the other electrode tab on the side.

[2] The electrical device assembly according to [1], wherein in the first welding step, the bus bar is joined to one surface of the electrode tab drawn out immediately from the electrical device cover. Body manufacturing method.

[3] In the first welding step, the one electrode tab is joined to the first surface of the bus bar,

3. The method of manufacturing an electrical device assembly according to claim 1, wherein, in the second welding step, the other electrode tab is joined to a second surface different from the first surface.

[4] In the first welding step, the joining is performed in a state where a surplus portion is left on a tip side of the one electrode tab,

In the second welding step, the surplus portion of the one electrode tab and the tip side of the other electrode tab are overlapped, and the overlap portion is joined to the second surface. The manufacturing method of the electrical device assembly as described.

5. The method of manufacturing an electric device assembly according to claim 1, wherein the bus bar is also a hollow bar-shaped member.

6. The method for producing an electrical device assembly according to claim 1, wherein the nose bar has a cross-sectional shape or L shape. By electrically connecting sheet-like electrode tabs drawn from each electrical device, the plurality of electrical devices are electrically connected in series and Z or in parallel, and the electrical connection between the electrode tabs A bus bar made of a conductive material is attached to each of the parts, and an electric device assembly comprising:

Of the predetermined number of the stacked electrical devices, one of the electrode tabs drawn from one of the electrical devices is joined to the first surface of the bus bar, and another electrical device adjacent to the one electrical device is connected. An electric device assembly in which the other electrode tab of the electric device on the side where the bus bar is not bonded is bonded to a second surface different from the first surface.