Terminal unit and method for manufacturing a terminal unit

Abstract

The present invention provides a terminal unit that allows a busbar to be reattached even after it has been removed, as well as a method for manufacturing the terminal unit. [Solution] The terminal unit 20 is provided on a battery cell 10 having an electrode portion. The terminal unit 20 comprises a terminal portion 21 electrically connected to the electrode portion, a joining member 25 having a first joining surface 25A which is one side in a predetermined direction joined to the terminal portion 21, and a second joining surface 25B which is the other side in the predetermined direction, and a busbar 27 joined to the second joining surface 25B of the joining member 25. The first joining portion 26 that joins the terminal portion 21 and the first joining surface 25A of the joining member 25, and the second joining portion 28 that joins the second joining surface 25B of the joining member 25 and the busbar 27 are provided so as not to overlap when viewed from a predetermined direction.

Description

Technical Field

[0001] The present invention relates to a terminal unit and a method for manufacturing the terminal unit.

Background Art

[0002] Patent Document 1 discloses an assembled battery configured by stacking a plurality (here, four) of cell batteries. In this cell battery, a negative electrode terminal portion and a positive electrode terminal portion are overlapped and fixed so as to be opposite to each other. Then, a bus bar for electrically connecting to a positive electrode fixing member is fixed to the external terminal of the negative electrode by welding.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the battery described in Patent Document 1, the bus bar is directly joined to the external terminal by welding. Therefore, when the bus bar is removed from the external terminal, welding traces (hereinafter referred to as "welding marks") remain on the surface of the external terminal where the bus bar is attached. For this reason, even if an attempt is made to attach the bus bar again to the attachment surface of the external terminal, the welding marks become an obstacle, and there is a possibility that a new bus bar cannot be attached.

[0005] In consideration of the above facts, an object of the present invention is to obtain a terminal unit and a method for manufacturing the terminal unit that can attach the bus bar again even if the bus bar is removed once.

Means for Solving the Problems

[0006] A terminal unit according to the first embodiment is a terminal unit provided on a battery cell having an electrode portion, comprising: a terminal portion electrically connected to the electrode portion; a joining member having a first joining surface which is one side in a predetermined direction joined to the terminal portion and a second joining surface which is the other side in the predetermined direction; and a busbar joined to the second joining surface of the joining member, wherein the first joining portion that joins the terminal portion and the first joining surface of the joining member and the second joining portion that joins the second joining surface of the joining member and the busbar are provided so as not to overlap when viewed from the predetermined direction.

[0007] In a terminal unit, when a busbar is removed from its mating part, traces of the busbar connection (hereinafter referred to as "busbar connection marks") remain on the mating part. For example, if a busbar is directly connected to a terminal, removing the busbar will leave busbar connection marks on the terminal. In this case, even if one attempts to reattach the busbar to the terminal, the busbar connection marks will get in the way, making it impossible to reattach the busbar. On the other hand, in the terminal unit according to the first embodiment, a joining member is provided having a first joining surface that is joined to the terminal portion and a second joining surface that is joined to the busbar. That is, a joining member is provided between the terminal portion and the busbar, and the terminal portion and the busbar are connected via the joining member. In this way, the busbar is not directly joined to the terminal portion but is joined via the joining member, so when the busbar is removed, the busbar joining mark will remain on the joining member and not on the terminal portion. Since the joining member is a separate component from the terminal portion, the joining member can be removed from the terminal portion. As a result, by replacing the joining member with the remaining busbar joining mark with a new joining member (specifically, a joining member without a busbar joining mark), there will be no busbar joining mark at the location where the busbar is joined. Therefore, even if the busbar is removed once, it can be reattached.

[0008] Furthermore, the first joint, which connects the terminal portion and the first joint surface of the connecting member, and the second joint, which connects the second joint surface of the connecting member and the busbar, are provided so as not to overlap when viewed from a predetermined direction. This makes it difficult for the first joint and the second joint to interfere with each other. Therefore, the terminal portion and the connecting member can be firmly joined, and the busbar and the connecting member can be firmly joined.

[0009] In the terminal unit according to the second embodiment, the first joint portion is provided on the outer periphery of the joint member, and the second joint portion is provided in the center of the joint member.

[0010] In the terminal unit according to the second embodiment, the first joint portion is provided on the outer circumference of the joining member, and the second joint portion is provided in the center of the joining member. This makes it less likely for the first joint portion and the second joint portion to interfere with each other. Therefore, the terminal portion and the joining member, and the busbar and the joining member can be firmly joined.

[0011] A terminal unit according to a third embodiment is a terminal unit provided on a battery cell having an electrode portion, comprising: a terminal portion electrically connected to the electrode portion; a joining member having a contact surface which is one side in a predetermined direction that abuts the terminal portion and a joining surface which is the other side in the predetermined direction; and a busbar joined to the joining surface of the joining member, wherein the surface of the terminal portion that abuts the joining member is provided with a joining mark which is the trace of the removal of the previous joining member that was joined to that surface, and the contact surface of the joining member is provided with a recess for accommodating the joining mark.

[0012] In a terminal unit, when removing and then reinstalling a busbar, it is conceivable to remove the connecting member (the connecting member before replacement) that is attached to one side of the terminal and install a new connecting member on the same side. In this case, a trace of the removal of the connecting member before replacement may remain on one side of the terminal. In the terminal unit according to the third embodiment, the contact surface of the joining member that contacts one surface of the terminal portion is provided with a recess for accommodating the joining mark. As a result, even if a joining mark remains on one surface of the terminal portion, the joining mark is accommodated in the recess of the joining member, so that the joining mark does not obstruct the contact between the terminal portion and the joining member. Therefore, it is possible to bring the joining member and the terminal portion into contact. Thus, the conductivity between the joining member and the terminal portion can be improved.

[0013] In the terminal unit according to the fourth embodiment, the busbar, the joining member, and the terminal portion are joined by a through-joint portion that penetrates the joining member in the predetermined direction.

[0014] In the terminal unit according to the fourth embodiment, the busbar, the joining member, and the terminal portion are joined by a through-joint that penetrates the joining member in a predetermined direction. This allows three members to be joined in a single step (the step of providing the through-joint). Therefore, the number of steps can be reduced compared to the case where the step of joining two members is repeated.

[0015] Furthermore, the through-connection electrically connects the terminal and the busbar. Therefore, conductivity between the terminal and the busbar can be improved.

[0016] In the terminal unit according to the fifth embodiment, the joint mark and the through joint are provided so as not to overlap when viewed from the predetermined direction, in the third embodiment or the fourth embodiment.

[0017] In the fifth embodiment of the terminal unit, the joint mark and the through joint are arranged so as not to overlap when viewed from a predetermined direction. This makes it difficult for the joint mark and the through joint to interfere with each other. Therefore, the terminal and the joining member can be firmly joined, and the busbar and the joining member can be firmly joined.

[0018] A method for manufacturing a terminal unit according to a sixth embodiment is a method for manufacturing a terminal unit provided in a battery cell having an electrode portion, the terminal unit comprising: a terminal portion electrically connected to the electrode portion; a first joining member having a first joining surface which is one surface in a predetermined direction joined to the terminal portion and a second joining surface which is the other surface in the predetermined direction; and a first busbar joined to the second joining surface of the first joining member, the method comprising: removing the first joining member from the terminal portion; installing a second joining member having a contact surface to the terminal portion in the state from which the first joining member has been removed, such that the contact surface contacts the terminal portion; and attaching a second busbar to the surface of the second joining member opposite to the contact surface.

[0019] A method for manufacturing a terminal unit according to the sixth embodiment includes the steps of removing a first joining member from the terminal portion and installing a second joining member having a contact surface in contact with the terminal portion from which the first joining member has been removed. A busbar joining mark remains on the first joining member from which the busbar has been removed. Therefore, by removing the first joining member with the busbar joining mark from the terminal unit and installing a new second joining member on the terminal portion, it is possible to prevent the presence of a busbar joining mark at the location where the busbar is joined. This makes it possible to reattach the busbar even after it has been removed once. [Effects of the Invention]

[0020] As described above, the terminal unit and the method for manufacturing the terminal unit according to the present invention have the excellent effect that the busbar can be reattached even after it has been removed. [Brief explanation of the drawing]

[0021] [Figure 1] This is a perspective view showing a battery cell according to an embodiment. [Figure 2] This is a schematic exploded perspective view showing the configuration around the electrode body of the battery cell according to the embodiment. [Figure 3] This is a schematic plan view showing the configuration of a battery pack according to the embodiment. [Figure 4] It is a perspective view showing a terminal unit provided in a battery cell according to an embodiment. [Figure 5] It is a schematic plan view showing a positive electrode side terminal unit provided in a battery cell according to an embodiment, showing a state before attaching a bus bar. [Figure 6] It is a cross-sectional view taken along the line A-A of FIG. 5. [Figure 7] It is a schematic plan view showing a positive electrode side terminal unit provided in a battery cell according to an embodiment, showing a state after attaching a bus bar. [Figure 8] It is a cross-sectional view taken along the line B-B of FIG. 7. [Figure 9] It is a schematic plan view showing a positive electrode side terminal unit provided in a battery cell according to an embodiment, showing a state after removing a bus bar. ​​​​​​​​​​​​​​​​​​​​​​​​​​​​This is a schematic vertical cross-sectional view showing a negative electrode terminal unit provided in a battery cell according to an embodiment, with the busbar attached. [Modes for carrying out the invention]

[0022] Hereinafter, a terminal unit and a method for manufacturing the terminal unit according to an embodiment of the present invention will be described with reference to Figures 1 to 19. For convenience in this embodiment, arrow X shown in each figure will be referred to as the width direction of the battery cell 10 (hereinafter simply as the "width direction"), arrow Y as the thickness direction of the battery cell 10 (hereinafter simply as the "thickness direction"), and arrow Z as the height direction of the battery cell 10 (hereinafter simply as the "height direction"). Of the width direction, thickness direction, and height direction, one direction is perpendicular to the other two directions.

[0023] As shown in Figures 1 and 2, the terminal units according to this embodiment (specifically, the positive terminal unit 20 and the negative terminal unit 30) are provided on the battery cell 10. Also, as shown in Figure 3, multiple battery cells 10 are combined to form a battery pack 100. The battery cell 10 is, for example, a lithium-ion battery that can be used as an on-board power source for electric vehicles, hybrid vehicles, etc.

[0024] [Battery pack] First, the configuration of the battery pack 100 will be described. As shown in Figure 3, the battery pack 100 has multiple battery cells 10 arranged in the thickness direction (Y direction). Adjacent battery cells 10 in the thickness direction are connected by busbars (first busbar, second busbar) 27 or busbar 37. Details of busbars 27 and 37 will be described later.

[0025] [Battery cell] Next, the battery cell 10 will be described. As shown in Figures 1 and 2, the battery cell 10 comprises a case 12 that constitutes the outer shell, a sealing plate 14 provided at the upper end of the case 12, an electrode body (electrode portion) 16 provided inside the case 14, a positive electrode side current collector terminal 18 and a negative electrode side current collector terminal 19 connected to the electrode body 16, and a positive electrode side terminal unit 20 and a negative electrode side terminal unit 30 attached to the sealing plate 14.

[0026] Case 12 is made of aluminum, for example. As shown in Figure 2, Case 12 has an opening 12A on the upper side in the height direction into which the electrode body 16 can be inserted. Case 14 is a rectangular box shape with the length direction as the width direction when viewed from the thickness direction.

[0027] The sealing plate 14 is, for example, made of aluminum. As shown in Figure 1, the sealing plate 14 is a rectangular plate with the thickness direction being the height direction and the length direction being the width direction. The opening 12A of the case 12 is sealed by the sealing plate 14. The sealing plate 14 is provided with a safety valve 14A and an inlet (not shown). The sealing plate 14 is also provided with a positive electrode through-hole (not shown) through which a part of the positive electrode terminal unit 20 is inserted, and a negative electrode through-hole (not shown) through which a part of the negative electrode terminal unit 30 is inserted.

[0028] The safety valve 14A is located in the center of the sealing plate 14 in the width direction. The safety valve 14A opens when the internal pressure of the case 12 reaches a predetermined pressure, releasing the gas inside the case 12.

[0029] The injection port is located near the safety valve 14A. The injection port is positioned to penetrate the sealing plate 14 in the vertical direction. The injection port is used when injecting electrolyte into the case 12. The injection port is closed by a cap 14B. The cap 14B is attached to the sealing plate 14 by laser welding or the like so that the inside of the case 12 becomes airtight.

[0030] The positive electrode through-hole is provided at one end of the sealing plate 14 in the width direction. The positive electrode through-hole is formed to penetrate the sealing plate 14 in the height direction. The shaft portion 22 of the positive electrode terminal unit 20, which will be described later, is inserted through the positive electrode through-hole.

[0031] The negative electrode through-hole is provided at the other end of the sealing plate 14 in the width direction. The negative electrode through-hole is formed to penetrate the sealing plate 14 in the height direction. The shaft portion 32 of the negative electrode terminal unit 30, which will be described later, is inserted through the negative electrode through-hole.

[0032] The electrode body 16 is constructed by winding together a positive electrode sheet, a negative electrode sheet, and a separator film (not shown) in a laminated state, so that its cross-section, when viewed from the width direction, is a rectangular shape that is flattened in the thickness direction. More specifically, as shown in Figure 2, the electrode body 16 is composed of a power generator 16A which constitutes its main part, and a positive electrode current collector 16B and a negative electrode current collector 16C which serve as electrode parts.

[0033] The power generator 16A is constructed by laminating the portion of the positive electrode sheet coated with the positive electrode active material, the portion of the negative electrode sheet coated with the negative electrode active material, and a separator film. This power generator 16A functions as a power storage unit in the battery cell 10.

[0034] The positive electrode current collector 16B constitutes one end in the width direction of the electrode body 16 and is formed by winding up the portion of the positive electrode sheet described above that is not coated with active material. The negative electrode current collector 16C constitutes the other end in the width direction of the electrode body 16 and is formed by winding up the portion of the negative electrode sheet described above that is not coated with active material.

[0035] The electrode body 16 is insulated from the case 14 by an insulating film 17. More specifically, the insulating film 17 is, for example, made of an insulating material such as polypropylene, and is formed in a bag shape that opens to the opening 12A side of the case 12. The electrode body 16 is then housed in the case 12 while wrapped in the insulating film 17.

[0036] The positive electrode current collector terminal 18 is, for example, made of aluminum. The positive electrode current collector terminal 18 is housed on one side of the case 12 in the width direction. The positive electrode current collector terminal 18 extends along the height direction and is plate-shaped with the plate thickness direction as the thickness direction. The lower end of the positive electrode current collector terminal 18 is joined to the positive electrode current collector portion 16B of the electrode body 16 by resistance welding or the like. The positive electrode current collector terminal 18 is electrically connected to the positive electrode current collector portion 16B. The upper end of the positive electrode current collector terminal 18 is joined to the positive electrode terminal unit 20. The positive electrode current collector terminal 18 is electrically connected to the positive electrode terminal unit 20. In this way, the positive electrode terminal unit 20 and the positive electrode current collector portion 16B of the electrode body 16 are electrically connected via the positive electrode current collector terminal 18.

[0037] The negative electrode current collector terminal 19 is, for example, made of copper. The negative electrode current collector terminal 19 is housed on one side of the width direction of the case 12. The negative electrode current collector terminal 19 extends along the height direction and is plate-shaped with the thickness direction being the plate thickness direction. The lower end of the negative electrode current collector terminal 19 is joined to the negative electrode current collector portion 16C of the electrode body 16 by resistance welding or the like. The negative electrode current collector terminal 19 is electrically connected to the negative electrode current collector portion 16C. The upper end of the negative electrode current collector terminal 19 is joined to the negative electrode terminal unit 30. The negative electrode current collector terminal 19 is electrically connected to the negative electrode terminal unit 30. In this way, the negative electrode terminal unit 30 and the negative electrode current collector portion 16C of the electrode body 16 are electrically connected via the negative electrode current collector terminal 19.

[0038] [Terminal Unit] Next, the positive terminal unit 20 and the negative terminal unit 30 provided on the battery cell 10 will be described. The positive terminal unit 20 and the negative terminal unit 30 have different structures. Below, the structure of the positive terminal unit 20 will be described first. In the following description, when simply referred to as "terminal unit," it includes both the positive terminal unit 20 and the negative terminal unit 30.

[0039] As shown in Figures 7 and 8, the positive terminal unit 20 includes a terminal portion 21 provided at the lower part in the height direction, a joining member (first joining member, pre-replacement joining member) 25 joined to the upper end of the terminal portion 21 in the height direction, and a busbar 27 joined to the upper end of the joining member 25 in the height direction.

[0040] The terminal portion 21 is formed of aluminum, for example. The terminal portion 21 is electrically connected to the electrode body 16 via the positive electrode side current collection terminal 18. As shown in Figures 4 and 8, the terminal portion 21 includes a shaft portion 22 that extends in the height direction and an external terminal 23 connected to the upper end of the shaft portion 22 in the height direction.

[0041] The shaft portion 22 is a cylindrical member. The shaft portion 22 is inserted through a positive electrode side through hole formed in the sealing plate 14. The lower end of the shaft portion 22 in the height direction is connected to the positive electrode side current collection terminal 18 (see Figure 2). The upper end of the shaft portion 22 in the height direction is connected to the lower surface of the external terminal 23.

[0042] The external terminal 23 is a plate-shaped member. When viewed from the height direction, the external terminal 23 is roughly rectangular in shape with its longitudinal direction as the width direction, and its four corners are curved. The upper end of the shaft portion 22 is connected to the approximate center of the lower surface of the external terminal 23 in the width direction (X direction) and thickness direction (Y direction). The upper surface 23A of the external terminal 23 is in surface contact with and joined to the joining member 25.

[0043] The joining member 25 is, for example, made of aluminum. The joining member 25 is a plate-shaped member. The shape of the joining member 25, when viewed from the height direction, is substantially the same as that of the external terminal 23. In detail, when viewed from the height direction, the joining member 25 is substantially rectangular with its longitudinal direction as the width direction, and its four corners are curved. Furthermore, the joining member 25 is provided so that its outer edge overlaps with that of the external terminal 23 when viewed from the height direction. The joining member 25 has a lower joining surface (first joining surface) 25A, which is the surface on one side in the height direction (predetermined direction) that is joined to the terminal portion, and an upper joining surface (second joining surface) 25B, which is the surface on the other side in the height direction.

[0044] The lower joining surface 25A of the joining member 25 is in surface contact with the upper surface 23A of the external terminal 23. Furthermore, the lower joining surface 25A is joined to the upper surface 23A of the external terminal 23. More specifically, the lower joining surface 25A of the joining member 25 is joined to the upper surface 23A of the external terminal 23 by ultrasonic bonding.

[0045] The upper joining surface 25B of the joining member 25 is the surface opposite to the lower joining surface 25A. The upper joining surface 25B is in surface contact with the lower surface of the busbar 27. Furthermore, the upper joining surface 25B is joined to the lower surface of the busbar 27. In detail, the upper joining surface 25B of the joining member 25 is joined to the lower surface of the busbar 27 by welding.

[0046] As described above, the upper surface of the terminal portion 21 (more specifically, the external terminal 23 of the terminal portion 21) and the lower joining surface 25A of the joining member 25 are joined by ultrasonic bonding. As shown in Figure 7, the ultrasonic bonding portion (first bonding portion) 26 that joins the terminal portion 21 and the joining member 25 by ultrasonic bonding has an outer peripheral bonding portion 26A provided on the outer periphery of the joining member 25 and a central bonding portion 26B provided in the center of the joining member 25. The outer peripheral bonding portion 26A is provided along the outer peripheral edge of the joining member 25 when viewed from the height direction and is provided over the entire circumferential area of ​​the joining member 25. The central bonding portion 26B is formed to be rectangular when viewed from the height direction.

[0047] The busbar 27 is made of aluminum, for example. The busbar 27 is a plate-shaped member. As shown in Figure 3, the busbar 27 is formed in a roughly rectangular shape with its longitudinal direction being the thickness direction (Y direction) when viewed from the height direction. The busbar 27 connects adjacent battery cells 10. More specifically, the busbar 27 connects the connecting members 25 provided on the positive electrode side terminal unit 20 of adjacent battery cells 10.

[0048] The busbar 27 is formed such that its length in the width direction (X direction) is longer than the length of the joining member 25 in the width direction (X direction). Furthermore, the busbar 27 is formed such that its length in the thickness direction (Y direction) is longer than the length of the joining member 25 in the thickness direction (Y direction).

[0049] As shown in Figure 8, the busbar 27 is in surface contact with the upper joining surface 25B of the joining member 25. The busbar 27 is also joined to the upper joining surface 25B of the joining member 25 by welding. The busbar 27 has a base portion 27A that is joined to the joining member 25, and a protrusion 27B that extends upward from the widthwise end of the base portion 27A. A through hole 27C that penetrates in the height direction is formed in the central part of the base portion 27A.

[0050] The joining member 25 and the busbar 27 are joined, for example, by laser welding. As shown in Figure 7, the welded joint 28 that joins the joining member 25 and the busbar 27 by welding extends along the thickness direction (Y direction). Also, as shown in Figure 8, the welded joint 28 extends from the upper surface of the base 27A to near the center of the joining member 25 in the height direction. Multiple welded joints 28 are provided.

[0051] The welded joint 28 is provided so as not to overlap with the ultrasonic joint 26 when viewed from the height direction. More specifically, the welded joint 28 is provided so as not to overlap with the ultrasonic joint 26 when viewed from the height direction. Furthermore, the welded joint 28 is provided between the outer peripheral joint 26A and the central joint 26B of the ultrasonic joint 26 when viewed from the height direction. Furthermore, two welded joints 28 are provided so as to sandwich the central joint 26B in the X-axis direction. More specifically, two are provided on one side of the central joint 26B in the X-axis direction, and two are provided on the other side of the central joint 26B in the X-axis direction.

[0052] Next, the negative terminal unit 30 will be described. As shown in Figure 19, the structure of the terminal portion 31 of the negative terminal unit 30 differs from that of the positive terminal unit 20. The joining member (second joining member) 35 and busbar 37 of the negative terminal unit 30 have the same structure as the joining member 25 and busbar 27 provided on the positive terminal unit 20, so a detailed explanation of them will be omitted below.

[0053] The terminal portion 31 of the negative electrode terminal unit 30 has a shaft portion 32 and an external terminal 33. The shaft portion 32 is made of copper, for example. The shaft portion 32 is a cylindrical member. The shaft portion 32 is inserted through a negative electrode through hole formed in the sealing plate 14. The lower end of the shaft portion 32 in the height direction is connected to the negative electrode current collection terminal 19 (see Figure 2). The upper end of the shaft portion 32 in the height direction is connected to the lower surface of the external terminal 33.

[0054] The external terminal 33 has a lower layer 33A connected to the shaft 32 and an upper layer 33B joined to the upper surface of the lower layer 33A. The lower layer 33A is formed of copper, for example. The upper layer 33B is formed of aluminum, for example.

[0055] The upper end of the shaft portion 32 is connected to the approximate center of the lower surface of the lower portion 33A in the width direction (X direction) and thickness direction (Y direction). The upper surface of the lower portion 33A is in surface contact with the lower surface of the upper portion 33B. In addition, the upper surface of the lower portion 33A is joined to the lower surface of the upper portion 33B.

[0056] The upper surface of the upper layer 33B is in surface contact with the lower surface of the joining member 25. Furthermore, the upper surface of the upper layer 33B is joined to the lower surface of the joining member 25. More specifically, the upper layer 33B is joined to the lower surface of the joining member 25 by ultrasonic bonding. However, the method of joining the upper layer 33B and the lower surface of the joining member 25 is not limited to ultrasonic bonding.

[0057] Furthermore, similar to the positive terminal unit 20, the welded joint 38 that joins the busbar 37 and the joining member 35 is provided so as not to overlap with the ultrasonic joint 36 that joins the terminal portion 31 and the joining member 25 when viewed from the height direction. Furthermore, as shown in Figure 3, the busbar 37 connects the connecting members 35 provided on the negative terminal units 30 of adjacent battery cells 10.

[0058] [Manufacturing method for terminal units] Next, we will explain the manufacturing method of the terminal unit. In the following explanation, we will first describe the manufacturing method of the positive terminal unit 20 using Figures 5 to 18.

[0059] First, as shown in Figures 5 and 6, the joining member 25 is placed on the upper surface 23A of the external terminal 23. Next, the upper surface 23A of the external terminal 23 and the lower joining surface 25A of the joining member 25 are joined by ultrasonic bonding. This forms an ultrasonic joint 26 (specifically, an outer peripheral joint 26A and a central joint 26B) between the upper surface 23A of the external terminal 23 and the lower joining surface 25A of the joining member 25. The order in which the outer peripheral joint 26A and the central joint 26B are formed is not particularly limited.

[0060] Next, as shown in Figures 7 and 8, the busbar 27 is placed on the upper joining surface 25B of the joining member 25. The busbar 27 is installed to connect adjacent battery cells 10 (see also Figure 3). Next, the upper joining surface 25B of the joining member 25 and the lower surface of the busbar 27 are joined by laser welding. At this time, laser welding is performed in four places. The laser welding is performed from the upper side of the busbar 27. This creates four welded joints 28 that extend from the upper surface of the busbar 27 to the inside of the joining member 25. Furthermore, the laser welding is performed so that, when viewed from the height direction, the entire welded joint 28 does not overlap with the ultrasonic joint 26.

[0061] In this way, the positive terminal unit 20 is manufactured. Furthermore, it is conceivable to rearrange the battery cells 10 in the battery pack 100 based on the degree of deterioration of each battery cell 10 over time. In other words, it is conceivable to change the arrangement of each battery cell 10 within the battery pack 100. By rearranging the battery cells 10, the lifespan of the battery pack 100 can be extended and its efficiency increased. To rearrange the battery cells 10, it is necessary to temporarily remove the busbars 27 that connect the battery cells 10, rearrange them, and then reattach the busbars 27. The following describes how to replace the busbars 27 of the positive terminal unit 20 manufactured as described above.

[0062] When replacing the busbar 27, first remove the busbar 27 from the joining member 25. At this time, as shown in Figures 9 and 10, a weld joint mark 128 remains on the upper joining surface 25B of the joining member 25 from which the busbar 27 has been removed. The weld joint mark 128 remains at the position where the welded joint 28 was provided.

[0063] Next, the joining member 25 is removed from the terminal portion 21. At this time, as shown in Figures 11 and 12, an ultrasonic bonding mark (bonding mark) 126, which is a trace of ultrasonic bonding, remains on the upper surface 23A of the external terminal 23 from which the joining member 25 was removed. The ultrasonic bonding marks 126 remain at the location where the ultrasonic bonding portion 26 was provided. Therefore, similar to the ultrasonic bonding portion 26, the ultrasonic bonding marks 126 have an outer peripheral bonding mark 126A provided on the outer periphery of the terminal portion 21 and a central bonding mark 126B provided in the center of the terminal portion 21.

[0064] Next, as shown in Figures 13 and 14, a new joining member 45 is placed on the upper surface 23A of the external terminal 23. The new joining member 45 will now be described. As shown in Figure 14, the lower surface 45A of the new joining member 45 is in contact with the upper surface 23A of the external terminal 23. The lower surface 45A of the joining member 45 is provided with a recess 46 that is recessed upward from the lower surface 45A. The recess 46 is configured to accommodate the ultrasonic bonding mark 126 when the lower surface of the joining member 45 (specifically, the surface without the recess 46) is in contact with the upper surface 23A of the external terminal 23. The recess 46 is formed in a shape corresponding to the shape of the ultrasonic bonding mark 126. That is, the recess 46 has an outer peripheral recess 46A provided on the outer periphery of the joining member 45 and a central recess 46B provided in the center of the joining member 45.

[0065] When placing a new joining member 45 on the upper surface 23A of the external terminal 23, as shown in Figure 14, the joining member 45 is placed so that the ultrasonic bonding marks 126 remaining on the upper surface 23A of the external terminal 23 are accommodated in the recesses 46. When the lower surface of the joining member 45 (specifically, the surface without the recesses 46) is in contact with the upper surface 23A of the external terminal 23, the recesses 46 accommodate the ultrasonic bonding marks 126. Specifically, the outer peripheral recess 46A accommodates the outer peripheral bonding marks 126A. In addition, the central recess 46B accommodates the central bonding marks 126B.

[0066] Next, as shown in Figures 15 and 16, the busbar 127 is placed on the upper surface of the new connecting member 45. The busbar 127 is installed to connect adjacent battery cells 10, similar to the busbar 27 (see also Figure 3).

[0067] Next, as shown in Figures 17 and 18, the busbar 127, the joining member 45, and the terminal portion 21 are joined by laser welding. Specifically, the busbar 127 and the joining member 45 are joined by laser welding, as is the joining member 45 and the terminal portion 21. That is, the busbar 127 and the terminal portion 21 are joined via the joining member 45. Laser welding forms through-welded sections (through-joints) 48 that extend linearly in the X direction. The laser welding is performed from the upper side of the busbar 127. This creates four through-welded sections 48 that penetrate the joining member 25 in the height direction from the upper surface of the busbar 127 and reach the inside of the terminal section 21. Furthermore, the laser welding is performed so that, when viewed from the height direction, the entire through-welded section 48 does not overlap with the ultrasonic bonding marks 126. In this way, the positive terminal unit 20 after the busbar has been replaced is manufactured.

[0068] Next, the manufacturing method of the negative electrode terminal unit 30 will be described. The negative electrode terminal unit 30 is joined to the terminal portion 31, which is formed by joining the lower portion 33A and the upper portion 33B, by ultrasonic welding using a joining member 35. The joining method is the same as that of the positive electrode terminal unit 20, so the explanation is omitted. The method for replacing the busbar 37 on the negative electrode terminal unit 30 is also the same as that of the positive electrode terminal unit 20, so the explanation is omitted. In the process of fixing the new busbar 37, laser welding is performed so that the lower end of the through-weld portion 48 is located on the upper portion 33B. In other words, the through-weld portion 48 does not reach the lower portion 33A.

[0069] [Effects / Effects] This embodiment provides the following effects. The effects of the positive terminal unit 20 are described below, but the negative terminal unit 30 also provides similar effects.

[0070] When a busbar, which is joined by welding, is removed from its mating part in the positive or negative terminal unit, traces of the connection with the busbar (hereinafter referred to as "welding marks") remain on the mating part. For example, if the busbar is directly joined to the terminal, removing the busbar will leave welding marks on the terminal. In this case, even if an attempt is made to reattach the busbar to the terminal, the welding marks will get in the way, making it impossible to reattach the busbar. As a result, the busbar cannot be reattached, and therefore, it was not possible to rearrange the battery cells 10 in the battery pack 100.

[0071] On the other hand, in the positive terminal unit 20 according to this embodiment, a joining member 25 is provided between the terminal portion 21 and the busbar 27, and the terminal portion 21 and the busbar 27 are connected via the joining member 25. Thus, the busbar 27 is not directly joined to the terminal portion 21, but is joined via the joining member 25, so when the busbar 27 is removed, the welding joint mark 128 will remain on the joining member 25 and not on the terminal portion 21. Since the joining member 25 is a separate component from the terminal portion 21, the joining member 25 can be removed from the terminal portion 21. As a result, by replacing the joining member 25 with which the welding joint mark 128 remains with a new joining member 25 (specifically, a joining member 25 without the welding joint mark 128), the welding joint mark 128 will not be present at the location where the busbar 27 is joined. Therefore, even if the busbar 27 is removed once, it can be reattached. Thus, in the battery pack 100, the battery cells 10 can be rearranged, etc.

[0072] Furthermore, the ultrasonic joint 26 that joins the terminal portion 21 and the lower joining surface 25A of the joining member 25, and the welded joint 28 that joins the upper joining surface 25B of the joining member 25 and the busbar 27, are provided so as not to overlap when viewed from the height direction. This makes it difficult for the ultrasonic joint 26 and the welded joint 28 to interfere with each other. Therefore, the terminal portion 21 and the joining member 25 can be firmly joined, and the busbar 27 and the joining member 25 can be firmly joined.

[0073] Furthermore, in this embodiment, the positive terminal unit 20 has a welded joint 28 provided between the outer peripheral joint 26A and the central joint 26B. This makes it less likely for the ultrasonic joint 26 and the welded joint 28 to interfere with each other. Therefore, the terminal 21 and the joining member 25 and the busbar 27 and the joining member 25 can be firmly joined.

[0074] As described above, when removing and then reinstalling the busbar 27 in the positive terminal unit 20, the bonding member 25 (the bonding member 25 before replacement) bonded to one surface of the terminal portion 21 is removed, and a new bonding member 45 is installed on the same surface. In this case, an ultrasonic bonding mark 126 remains on one surface of the terminal portion 21, which is the trace of the removal of the bonding member 25 before replacement. In this embodiment, the positive terminal unit 20 has a recess 46 on the contact surface of the new bonding member 45 that contacts one surface of the terminal portion 21, which accommodates the ultrasonic bonding mark 126. As a result, even if an ultrasonic bonding mark 126 remains on one surface of the terminal portion 21, the ultrasonic bonding mark 126 is accommodated in the recess 46 of the new bonding member 45. Therefore, the ultrasonic bonding mark 126 does not hinder contact between the terminal portion 21 and the new bonding member 45. Consequently, it is possible to bring the new bonding member 45 and the terminal portion 21 into contact. Thus, the conductivity between the bonding member 25 and the terminal portion 21 can be improved.

[0075] Furthermore, in the positive terminal unit 20 according to this embodiment, the busbar 27, the joining member 45, and the terminal portion 21 are joined by a through-weld portion 48 that penetrates the joining member 45 in the height direction. This allows the busbar 27 and the joining member 45, as well as the joining member 45 and the terminal portion 21, to be joined in a single step (the step of providing the through-weld portion 48). Therefore, the number of steps can be reduced compared to the case where the steps of joining the busbar 27 and the joining member 45 and joining the joining member 45 and the terminal portion 21 are performed separately.

[0076] Furthermore, the through-weld portion 48 electrically connects the terminal portion 21 and the busbar 27. Therefore, conductivity between the terminal portion 21 and the busbar 27 can be improved.

[0077] Furthermore, in this embodiment, the positive terminal unit 20 is provided such that the ultrasonic bonding marks 126 and the through-weld portion 48 do not overlap when viewed from the height direction. This makes it difficult for the ultrasonic bonding marks 126 and the through-weld portion 48 to interfere with each other. Therefore, the terminal portion 21 and the joining member 25 can be firmly joined, and the busbar 27 and the joining member 25 can be firmly joined.

[0078] Although the terminal unit and the method for manufacturing the terminal unit according to the embodiment have been described above, the present invention can be modified as appropriate without departing from the spirit of the invention.

[0079] For example, in the above embodiment, an example was described in which the lower joining surface 25A of the joining member 25 is joined to the upper surface of the external terminal 23 by ultrasonic bonding, but the present invention is not limited to this. The method of joining the lower joining surface 25A and the upper surface of the external terminal 23 is not limited to ultrasonic bonding.

[0080] Furthermore, although the above embodiment describes an example in which the upper joining surface 25B of the joining member 25 is joined to the lower surface of the busbar 27 by welding, the present invention is not limited to this. The method of joining the upper joining surface 25B and the lower surface of the busbar 27 is not limited to welding.

[0081] Furthermore, although the above embodiment describes an example in which the shaft portion 22 and the external terminal 23 of the terminal portion 21 are separate, the present invention is not limited to this. The shaft portion 22 and the external terminal 23 of the terminal portion 21 may be integrated. Also, the shapes of the shaft portion 22 and the external terminal 23 of the terminal portion 21 are not limited to the shapes described above. For example, the shaft portion 22 and the external terminal 23 may be a single cylindrical shape. [Explanation of Symbols]

[0082] 10 battery cells 12 cases 12A opening 14 cases 14 Sealing plate 14A Safety Valve 14B Cap 16 Electrode body (electrode part) 16A generator 16B Positive electrode current collector 16C Negative electrode current collector 17 Insulating film 18 Positive side current collection terminal 19 Negative side current collection terminal 20 Positive terminal unit 21 Terminal section 22 Shaft section 23 External terminals 23A Top 25. Joining members (first joining member, joining member before replacement) 25A Lower joint surface 25B Upper joint surface 26 Ultrasonic joint (1st joint) 26A Outer joint 26B Center joint 27 Bass Bar (1st Bass Bar) 27A base 27B Convex part 27C through hole 28. Welded joint (second joint) 30 Negative terminal unit 31 Terminal section 32 Shaft section 33 External terminals 33A Lower part 33B Upper part 35 Joining member (second joining member) 36 Ultrasonic joint 37 Busba 38 Welded joint 45 Joining member 45A Bottom 46 recess 46A Outer peripheral recess 46B Central recess 48 Through-weld joint (through-connection) 100 battery packs 126 Ultrasonic bonding marks (bonding marks) 126A Outer joint trace 126B Center joint trace 127 Basba (2nd Basba) 128 Welding marks

Claims

1. A terminal unit provided in a battery cell having an electrode portion, A terminal portion electrically connected to the electrode portion, A joining member having a first joining surface which is one side in a predetermined direction that is joined to the terminal portion, and a second joining surface which is the other side in the predetermined direction, The joining member comprises a busbar joined to the second joining surface of the joining member, A terminal unit in which a first joint portion that joins the terminal portion and the first joint surface of the joining member, and a second joint portion that joins the second joint surface of the joining member and the busbar, are provided so as not to overlap when viewed from the predetermined direction.

2. The first joint portion is provided on the outer periphery of the joint member, The terminal unit according to claim 1, wherein the second joint is provided in the center of the joint member.

3. A terminal unit provided in a battery cell having an electrode portion, A terminal portion electrically connected to the electrode portion, A joining member having a contact surface which is one side in a predetermined direction that abuts the terminal portion, and a joining surface which is the other side in the predetermined direction, The joining member comprises a bus bar that is joined to the joining surface of the joining member, The surface of the terminal portion that contacts the connecting member is provided with a joint mark, which is the trace of the removal of the previous connecting member that was joined to that surface. A terminal unit wherein the contact surface of the joining member is provided with a recess for accommodating the joining mark.

4. The terminal unit according to claim 3, wherein the busbar, the joining member, and the terminal portion are joined by a through-joint portion that penetrates the joining member in the predetermined direction.

5. The terminal unit according to claim 4, wherein the joint mark and the through joint are provided so as not to overlap when viewed from the predetermined direction.

6. A method for manufacturing a terminal unit provided in a battery cell having an electrode portion, A terminal portion electrically connected to the electrode portion, A first joining member having a first joining surface which is one surface in a predetermined direction that is joined to the terminal portion, and a second joining surface which is the other surface in the predetermined direction, In the terminal unit having a first busbar joined to the second joining surface of the first joining member, A step of removing the first joining member from the terminal portion, The process involves installing a second joining member having a contact surface on the terminal portion with the first joining member removed, such that the contact surface contacts the terminal portion, A method for manufacturing a terminal unit, comprising the step of attaching a second busbar to the surface of the second joining member opposite to the contact surface.

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