JP2012109275A - Electric device assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an electric device assembly in which a welding failure is hard to occur between an electrode tab and a bus bar and which is advantageous for simplifying a pressing jig used for welding.SOLUTION: A battery pack 50 includes a plurality of battery cells 20A to 20D connected in series. An electrode tab 25a from a battery cell 20A is bonded to a top face of a bus bar 41. An electrode tab 25b from a battery cell 20B is bonded to a side face of the bus bar. First, in a first welding step, the bus bar 41 is bonded to one electrode tab 25a with the battery cell 20 placed in a single state. Next, in a second welding step, the electrode tab 25b is bonded to the side face of the bus bar with the battery cells with the bus bar superimposed thereon.

Description

  The present invention relates to an electrical device assembly in which a plurality of electrical devices (for example, batteries, capacitors, etc.) that store and output electrical energy are collected, and more particularly to an electrical device assembly in which electrical devices are electrically connected.

  Conventionally, as a kind of thin battery, a film-covered battery in which a battery element is housed together with an electrolytic solution in a packaging bag made of a laminate 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 gathered 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. 2004-3225. As shown in FIG. 1, the assembled battery 150A has a configuration in which four battery cells C1 to C4 are stacked in four stages, 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. The relationship between two battery cells C1 and C2 adjacent to each other in the stacking direction will be described 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. The bus bars 141 are connected to each other.

  By the way, although Unexamined-Japanese-Patent No. 2004-3225 describes using welding etc. to connect the bus bar 141 and the electrode tab 125, there is no sufficient description about the details. Therefore, for example, in the configuration as shown in FIG. 2, when trying to weld the bus bar and the electrode tab, the following problem may occur.

  In the assembled battery 150B of FIG. 2, four battery cells C1 to C4 are connected in series. Specifically, the front end sides of 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. 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, the laser beam may be irradiated from the direction indicated by the arrow B.

  However, in order to perform welding joint by such a method, it is necessary to position and hold the two electrode tabs 125 and the bus bar 141 with each other, and this holding operation is a relatively complicated process. Further, in order to perform such holding, a jig having a relatively complicated structure (pressing jig) is required.

  As described above, the manufacturing problem related to the conventional configuration has been described by taking the battery as an example. However, such a problem may occur not only in the battery but also in other electric devices (for example, a capacitor).

  The present invention has been made in view of the above-mentioned problems, and the object thereof is to make it difficult to cause poor welding between the electrode tab and the bus bar, and to simplify the pressing jig used during welding. It is another object of the present invention to provide an advantageous electrical device assembly.

  In order to achieve the above object, the electrical device assembly of the present invention is configured such that a plurality of electrical devices are connected in series and / or in parallel by electrically connecting sheet-like electrode tabs extending from each electrical device. An electrical device assembly in which a bus bar made of a conductive material is attached to each of the electrical connections between the electrode tabs, wherein each electrical device has at least two electrode tabs. And the first electrode tab that is one of the at least two electrode tabs has at least an extension extending from the electrical device, and the first electrode tab of the at least two electrode tabs A second electrode tab different from the first electrode tab includes a first extension extending from the electrical device and a direction different from the direction in which the first extension extends. The extension of the first electrode tab of the first electrical device among the plurality of the stacked electrical devices having a second extension portion extending from the first extension portion A second portion of the second electrode tab of the second electrical device adjacent to the first electrical device is joined to the first surface of the bus bar, the second extension of the bus bar, It is joined to a second surface different from the first surface.

  In the electrical device assembly of the present invention, the first electrode tab and the second 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 step, first, the bus bar and the first electrode tab are joined. Next, as a second welding process, the bus bar and the second electrode tab are joined. In each of the first and second welding processes, only positioning between two members such as the first electrode tab and the bus bar and the second electrode tab and the bus bar may be performed. That is, it is not necessary to position three members (two electrode tabs and one bus bar) that are not yet joined to each other as in the conventional welding process. For this reason, generation | occurrence | production of the welding defect resulting from positioning of three members being made inaccurately is suppressed. Moreover, the reliability of the welded part formed will also 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, it is possible to simplify the pressing jig used during welding.

  According to the present invention, as described above, poor welding between the electrode tab and the bus bar is unlikely to occur, and it is possible to simplify the holding jig used during welding.

It is a perspective view which shows the structure of the conventional assembled battery. It is a figure for demonstrating the problem which may arise when welding by the conventional method. It is a top view which shows the structure of the assembled battery which concerns on 1st Embodiment. It is a perspective view which shows the battery cell used for the assembled battery of FIG. 3 in a single-piece | unit state. It is a perspective view for demonstrating an example of the form of a welding part. It is a figure for demonstrating one Embodiment of the manufacturing method of this invention. It is a top view which shows the other structural example of a bus bar. It is a top view which shows an example of a jig | tool suitable with respect to a hollow bus bar. It is a top view which shows the structure of the assembled battery of 2nd Embodiment. It is a figure for demonstrating another example of the manufacturing method of this 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 electric device assembly manufactured according to the present invention. 4 is a perspective view showing a battery cell used in the assembled battery of FIG. 3 in a single state.

  As shown in FIG. 3, the assembled battery of this embodiment is an assembly of battery cells 20 </ b> A to 20 </ b> D and has a four-tiered configuration. Each battery cell is electrically connected in series so that the voltage corresponding to the number of battery cells is output.

  Battery cells 20 </ b> A to 20 </ b> D (hereinafter also simply referred to as battery cell 20) all have the same structure, and as shown in FIG. 4, in detail, a film-clad battery having a frame. In the battery cell 20, a thin battery element 22 that outputs a predetermined electromotive force (for example, 3.6 V) is housed together with an electrolyte in a sealed space formed by the exterior film 24. The exterior film 24 has a structure in which two films are bonded to each other, 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 25 a and a negative electrode tab 25 b are drawn out from two sides on the short side of the rectangular exterior film 24.

  The battery element 22 has a sheet-like positive electrode whose surface is coated with a positive electrode active material and a sheet-like negative electrode whose surface is coated with a negative electrode active material alternately stacked with a separator interposed therebetween. The thickness is, for example, about several mm.

  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 as 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.

  Refer to FIG. 3 again. The bus bar 41 is a bar-shaped member having a rectangular cross section made of a conductive material 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 this 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, and the other battery The electrode tab 25b from the cell (for example, 20B) is joined to the side surface 41s of the bus bar 41. For this joining, for example, laser welding can be used. In the present 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 bus bar side surface are joined by the welded portion 38 that is also formed by laser welding. With such a configuration, the electrode tabs 25 a and 25 b are electrically connected via the bus bar 41.

  The welded portion 37 may be a plurality of spot-like welded portions 37A as shown in FIG. 5A, for example. Alternatively, the welded portion 37 may be a linear welded portion 37B as shown in FIG. The same applies to the welded portion 38. 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-described configuration will be described with reference to FIG. FIG. 6 is a diagram for explaining the manufacturing method of the present embodiment, and shows four steps from FIG. 6A to FIG. 6D.

  First, as shown in FIG. 6A, 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 front end side and connected to the side surface of the bus bar as described later. In order to realize this, it is necessary to make the electrode tab 25a relatively longer than the electrode tab 25a. Because.

  Next, as shown in FIG. 6B, the tip side of the electrode tab 25 b is bent, for example, at a right angle in accordance with the shape of the bus bar 41. 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). By this step, a predetermined number of battery cells 20 are produced in which one electrode tab 25b is bent and the bus bar 41 is welded to the other electrode tab 25a.

  This first welding process is performed in a state where one electrode tab 25a and the 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 bus bar upper surface), thereby forming a welded portion 37 extending in the vertical direction.

  Such a welding process is advantageous in that 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. In this welding process, the electrode tab 25a drawn straight (the electrode tab 25a in an initial state where bending is not 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 bent electrode tab 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.

  After the four battery cells are superposed in this manner, laser welding is then sequentially performed for each electrical connection portion as shown in FIG. 6D (second welding step). 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 bus bar side surface). As a result, the electrode tab 25 b and the bus bar 41 are joined, and the electrode tabs 25 a and 25 b are interconnected via the bus bar 41.

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

  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, and the other electrode tab Since the process of joining 25b and the bus bar 41 is a separate welding process, the following advantages are obtained. That is, in the conventional method shown in FIG. 2, it is necessary to position and hold a total of three members including two electrode tabs and a bus bar. On the other hand, in the configuration of the present embodiment, it is only necessary to perform positioning between two members such as one electrode tab 25 and the bus bar 41 and the other electrode tab 25b and the bus bar 41 in each welding process. There is no need to position the three members that are not. Therefore, poor welding due to inaccurate positioning of the three members is less likely to occur, and the reliability of the formed welded portion is improved.

  As mentioned above, although one Embodiment of this invention was described, this invention can be variously changed besides the above. For example, in the manufacturing procedure described above, the electrode tab 25b has already been bent in the process of FIG. 6B, but this bending process may be performed in the process of FIG. 6D. . That is, after overlapping a plurality of battery cells, the tip side of the electrode tab 25b may be bent along the side surface of the bus bar.

  Further, the shape of the bus bar 41 is not limited to the above. For example, a hollow bus bar 42 as shown in FIG. 7A may be used. When the hollow bus bar 42 is used in this way, 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.

  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, it is possible to suppress the temperature rise of the electrode tabs 25a and 25b. Alternatively, the cooling air may be sent when the electrode tabs 25a, 25b and the bus bar 42 are welded.

  The bus bar may be a bus bar 43 having a C-shaped cross section as shown in FIG. Although depending on the direction in which the opening of the C-shaped cross section is oriented, as shown in FIG. 7B, when the bus bar 43 is arranged so that the opening faces the electrode tab 25b, It is also possible to pass cooling air. Thereby, regarding the point which sends cooling air, the effect similar to the said hollow bus bar 42 will be obtained.

  The bus bar may be an L-shaped cross-section bus bar 44 as shown in FIG. Each of the three bus bars 42, 43, 44 shown in FIG. 7 has upper surfaces 42u, 43u, 44u to which the electrode tabs 25a are joined, and side surfaces 42s, 43s, 44s to which the electrode tabs 25b are joined. In common.

  By the way, comparing the case where the solid bus bar 41 as shown in FIG. 3 is used with the case where the hollow bus bar 42 as shown in FIG. 7A is used, it is more efficient to use the hollow bus bar 42. It is preferable at the point which can perform typical welding. That is, 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, such heat does not easily propagate, so that the energy of the laser beam is further increased. This is because it can be used efficiently. The same effect can be obtained with the bus bars 43 and 44, though depending on the thickness of the portion irradiated with the laser beam.

(Second Embodiment)
Next, with reference to FIG. 9, another configuration to which the manufacturing method of the present invention can be applied will be described. In the above-described embodiment, 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, but the present invention is not limited thereto. Like the assembled battery 51 of FIG. 9, the tip side of the electrode tab 25a and the tip side of the electrode tab 25b may overlap each other. In FIG. 9, as an example, of the two electrode tabs 25a, 25b, the positive electrode tab 25a is relatively folded inward and comes into contact with the side surface 41s of the bus bar 41, but the opposite is true. 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, 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. 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. 10A, 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 25 a and 25 b 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 distal end side of the electrode tab 25a, that is, in a state where some surplus portion is left on the distal end side. This surplus portion is bent along the side surface of the bus bar 41. This folding step may be performed either before or after welding.

  Next, the battery cells with the bus bar obtained in the step of FIG. 10B are overlapped as shown in FIG. 10C, and the bent electrode tabs 25b are pressed against the side surfaces of the bus bar. Then, the laser beam B2 is irradiated (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.

  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, so the first embodiment. Similar effects can be obtained.

  In the step of FIG. 10C, the welding method of the present embodiment and the welding method shown in FIG. 2 are used in that the tip sides of the two electrode tabs 25a and 25b are pressed against the side surface 41s of the bus bar. Seems to be in common, but they differ in the following respects. 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. In contrast, in the method of the present embodiment, the bus bar 41 and the electrode tab 25a are already welded at the time of welding. Therefore, this step is substantially different from the method of 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. May be. The irradiation directions of the laser beams B1 and B2 are not limited to those perpendicular to each surface of the bus bar, but may be a predetermined angle. In the above description, first, the electrode tab 25a on the positive electrode side and the bus bar are joined, and then the electrode tab 25b on the negative electrode side and the bus bar are joined, but this order is reversed. May be.

  In this specification, the “electric device” corresponds to the battery cell 20 in the above embodiment. The type of the battery cell 20 is not particularly limited, such as a lithium ion secondary battery, a nickel metal hydride battery, a nickel cadmium battery, a lithium metal primary / secondary battery, or a lithium polymer battery. It is not something that can be done. For example, it is possible to use a battery cell in which the battery element 22 is sealed with a rigid can or the like instead of the exterior film 24 (see FIG. 5). Furthermore, the “electric device” is not limited to a battery, and may function as a capacitor, for example.

Claims (5)

A plurality of the electric devices are electrically connected in series and / or in parallel by electrically connecting sheet-like electrode tabs extending from each electric device, and an electrical connection portion between the electrode tabs Each of which is an electrical device assembly to which a bus bar made of a conductive material is attached,
Each electrical device has at least two electrode tabs;
A first electrode tab, which is one of the at least two electrode tabs, has at least an extension extending from the electrical device;
Of the at least two electrode tabs, a second electrode tab different from the first electrode tab includes a first extension extending from the electrical device, and the first extension extending. Having a second extension extending from the first extension in a direction different from the existing direction;
Of the plurality of stacked electrical devices, the extending portion of the first electrode tab of the first electrical device is bonded to the first surface of the bus bar,
The second extension of the second electrode tab of the second electric device adjacent to the first electric device is bonded to a second surface of the bus bar different from the first surface. An electrical device assembly. A plurality of the electric devices are electrically connected in series and / or in parallel by electrically connecting sheet-like electrode tabs extending from each electric device, and an electrical connection portion between the electrode tabs Each of which is an electrical device assembly to which a bus bar made of a conductive material is attached,
Each electrical device has at least two electrode tabs;
A first electrode tab, which is one of the at least two electrode tabs, has at least an extension extending from the electrical device;
Of the at least two electrode tabs, a second electrode tab different from the first electrode tab includes a first extension extending from the electrical device, and the first extension extending. Having a second extension extending from the first extension in a direction different from the existing direction;
The electrical devices are alternately stacked such that the extending portions of the first electrode tabs face the first extending portions of the second electrode tabs of the adjacent electrical devices,
The extension of the first electrode tab is joined to the first surface of the bus bar;
The second extension part of the second electrode tab having the first extension part facing the extension part of the first electrode tab is the first surface of the bus bar. An electrical device assembly bonded to another second surface. At least three of the electrical devices are stacked;
The electrical device disposed in the middle of the at least three electrical devices is configured such that the extension portion of the first electrode tab is adjacent to the electrical device disposed in the middle of each of the two electrical devices. The electrical device assembly according to claim 2, wherein the electrical device assembly is alternately stacked so as to face the first extending portion of the second electrode tab. The first electrode tab has a second extension portion extending from the first extension portion in a direction different from a direction in which the first extension portion extends,
The said 2nd extension part of the said 1st electrode tab and the said 2nd extension part of the said 2nd electrode tab overlap each other, and are joined to the said 2nd surface. 4. The electrical device assembly according to any one of items 1 to 3.   5. The electric device assembly according to claim 1, wherein the bus bar is a member having a U-shaped or L-shaped cross-section, or a member having a hollow shape.

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