Conductive component for secondary battery, and method for manufacturing same

Abstract

The present invention provides a conductive component for a secondary battery and a method for manufacturing the same, the conductive component being manufactured by a friction stir spot welding method and capable of maintaining a low electric resistance value even in a form where the thickness of a joint portion is minimized. A conductive component 10 for a secondary battery according to the present invention is provided with a plurality of metallic foil materials 1a-1j having projecting portions at both left and right ends in the longitudinal direction, and two metal plate materials 2, 3 having recessed portions. The metal plate materials 2, 3 respectively have parts 2a, 2b, 3a, 3b having different thicknesses. The plurality of metal foil materials 1a-1j are stacked over the thin parts 2a, 3a of the metal plate materials 2, 3, and, in a state in which the projecting portions of the metal foil materials 1a-1j are fitted into the recessed portions of the metal plate materials 2, 3, the metal foil materials 1a-1j and the metal plate materials 2, 3 are joined together by a friction stir spot joining method.

Description

Current-carrying component for secondary battery and manufacturing method thereof

[0001] The present invention relates to an electric component for use in secondary batteries mounted mainly on automobiles and the like, and a method for manufacturing the same.

[0002] Current-carrying components formed from two or more sheets of plate or foil material, particularly current-carrying components for use in secondary batteries in automobiles, etc., are also called bus bars, and are made of highly conductive materials such as aluminum alloys and copper alloys, as disclosed in Patent Documents 1 and 2. A schematic plan view of a conventional current-carrying component 100 for a secondary battery is shown in Figure 55, and a schematic front view of the conventional current-carrying component 100 for a secondary battery is shown in Figure 56.

[0003] The secondary battery electrical component 100 shown in Figures 55 and 56 is made by bridging multiple sheets of metal foil material 101 and two sheets of metal plate material (thicker than the metal foil material) 102, 103, and fixing the overlapping areas (jointing areas 151, 152) by friction stir spot welding.

[0004] Patent No. 6971990 Patent No. 6442975

[0005] However, in busbars that carry large currents exceeding 1000 A when energized, it is necessary to increase the cross-sectional area of ​​the components to suppress heat generation during energization. If the thickness of each component, made of metal foil material and metal plate material, is increased to ensure this cross-sectional area, the friction stir spot welded joint (joints 151 and 152 shown in FIGS. 55 and 56 ) will be twice as thick. As a result, there is a problem of interference with surrounding components, restricting the shape of the component.

[0006] Therefore, an object of the present invention is to provide an electrical component for a secondary battery manufactured by a friction stir spot joining method, which can maintain a low electrical resistance value even when the thickness of the joint is minimized, and a method for manufacturing the same.

[0007] Another issue is that the distance between the left and right bolts used to secure the current-carrying component can have an assembly error of up to 2 mm due to variations in the assembly position of the secondary battery component to which it is attached. In the current-carrying component 100 for secondary batteries shown in Figures 55 and 56, if the variation in assembly position is negative, the metal foil laminated portion bends, allowing the distance between the left and right bolts to be shortened. However, if the variation in assembly position is positive, it is difficult to align the bolt fastening position by pulling the component. Additionally, tightening the bolt while pulling it is an inefficient process.

[0008] For this reason, bolt holes are typically slotted to accommodate variations in assembly position, but this is undesirable for current-carrying components that pass large currents because it reduces the cross-sectional area of ​​the component. Alternatively, the metal foil laminated section can be curved to accommodate variations in assembly position. However, when the number of metal foil layers is as large as 20 or more, it is difficult to bend all of the metal foil layers in a single process, and the metal foil may tear during molding. Furthermore, when layers are bent and laminated one by one, the cycle time, which is the number of manufacturing steps, increases as the number of layers increases.

[0009] Therefore, some embodiments of the present invention have an objective of providing an electrical component for a secondary battery manufactured by a friction stir spot joining method, which can be flexibly assembled to various components such as the secondary battery body, even in the case of an electrical component for a secondary battery having a metal foil material formed from multiple layers, and which can maintain a low electrical resistance value, and a method for manufacturing the same.

[0010] Furthermore, one of several other problems is the following. As a conventional technique, there is a method disclosed in Patent Document 2 in which an uneven shape is used to prevent the joint from becoming twice as thick. However, when joining a laminated metal foil material 111 and a metal plate material 113, gaps G are likely to occur at the butting surfaces of the uneven shapes. For example, the lengths of the end faces of the metal foil material 111 vary when the metal foil material 111 is stacked, as shown in FIG. 57( a), or the metal foil material 111 shifts when a joining tool is inserted, as shown in FIG. 57( b). This reduces the contact area between the laminated metal foil material 111 and the metal plate material 113, reducing the thermal conductivity of the secondary battery current-carrying component and causing heat generated near the joint to stagnate.

[0011] Therefore, some embodiments of the present invention have the objective of providing an electrically conductive component for a secondary battery manufactured by a friction stir spot joining method, which can maintain a low electrical resistance even when the thickness of the joint is minimized, and which ensures a sufficient contact area between the metal foil material and the metal plate material.

[0012] In addition, one of several other issues is the following. One method involves increasing the contact area between the metal foil material and the metal plate material by creating a concave or convex shape or other shape along the short side of the metal foil material or the metal plate material. For example, when joining metal foil material cut into a convex shape, depending on the shape of the convex portion, the metal foil material may tear or be distorted by the heat of joining, which can easily create gaps at the abutment surface with the concave shape (short side) of the metal plate material. This reduces the contact area between the laminated metal foil material and the metal plate material, reducing the thermal conductivity of the secondary battery current-carrying component and causing the heat generated to stagnate near the joint.

[0013] Therefore, some embodiments of the present invention aim to provide a method for manufacturing an electrical component for a secondary battery that can maintain a low electrical resistance even when the thickness of the joint is minimized, and that can ensure a sufficient contact area between the metal foil material and the metal plate material.

[0014] The current-carrying component for a secondary battery of the present invention includes at least a plurality of metal foil materials and two metal plate materials, and the metal plate materials have portions of different thicknesses. That is, the same metal plate material has two portions, one thin and one thick. With a plurality of metal foil materials stacked above the thin portions of the metal plate material, the metal foil materials and the metal plate materials are joined to each other by a friction stir spot welding method. The portions joined by the friction stir spot welding method can be located at least in two positions in the longitudinal direction and the thickness direction of the current-carrying component for a secondary battery.

[0015] The sum of the thicknesses of the thin portions of the metal foils and metal plates may be equal to the thickness of the thick portions of the metal plates. In this case, the number of metal foils may be 10 or more, and the thickness of each may be 0.21 mm or less. The metal foils and metal plates may be made of the same metal or different metals. In this case, the metal foils may be made of aluminum, aluminum alloys, copper, or copper alloys.

[0016] Next, in the invention of a current-carrying component for a secondary battery and a manufacturing method thereof, two metal plates having portions of different thicknesses and multiple metal foils are used, and the multiple metal foils are stacked above the thinner portions of the metal plates (Step 1). Then, the friction stir welding tool is inserted into the metal foils from above while rotating (Step 2). Finally, the friction stir welding tool is removed from the metal foils (Step 3).

[0017] In the first step, the plurality of metal foil materials may be provided with protruding portions protruding in the longitudinal direction at both ends thereof, and the two metal plate materials may be provided with recessed portions extending in the longitudinal direction at one end thereof, and the protruding portions of the plurality of metal foil materials may be fitted into the recessed portions of the two metal plate materials, respectively, and the friction stir welding tool may be inserted into the metal foil materials from above while rotating the friction stir welding tool. Furthermore, in the second step, the distance between the friction stir welding tool and the metal plate materials may be set in the range of 0.5 mm to 2.0 mm.

[0018] The convex portion of the metal foil may be curved along the longitudinal direction of the metal foil, and the concave portion of the metal plate may be curved along the longitudinal direction of the metal plate.

[0019] In some embodiments, the current-carrying component for a secondary battery of the present invention includes a plurality of metal foil sheets stacked in the thickness direction and two metal plate sheets having portions of different thicknesses. The metal foil sheets are formed from two first metal foil sheets extending in the longitudinal direction and two second metal foil sheets having a longitudinal length shorter than the first metal foil sheets. The two second metal foil sheets are separated into left and right halves and sandwiched between the two first metal plates. The first metal plate sheets and the separated left and right second metal foil sheets are alternately stacked in the thickness direction. The first and second metal foil sheets are placed above the thinner portions of the metal plates, and the left and right ends of the first and second metal foil sheets are joined to the two metal plates. In this case, the joints between the metal plate sheets and the first and second metal foil sheets can be formed at the locations where the metal plate sheets contact the first and second metal foil sheets in the longitudinal and thickness directions, respectively. The sum of the thicknesses of the thin portions of the first and second metallic foils and the metallic plate may be the same as the thickness of the thick portions of the metallic plate. The number of layers of the first and second metallic foils may be nine or more, and the thickness of each of the first and second metallic foils may be 0.21 mm or less. The first and second metallic foils may be made of aluminum, an aluminum alloy, copper, or a copper alloy.

[0020] In some embodiments, the method for manufacturing a secondary battery current-carrying component of the present invention includes stacking two metal sheets having portions of different thicknesses and multiple metal foil sheets above the thinner portions of the metal sheets (step 1). Then, while rotating, the friction stir welding tool is inserted into the metal foil sheets from above (step 2). Finally, the friction stir welding tool is removed from the metal foil sheets (step 3). In step 1, each of the multiple metal foil sheets may have a convex portion protruding along its longitudinal direction at both ends, and each of the two metal sheets may have a concave portion extending along its longitudinal direction at one end. The convex portions of the multiple metal foil sheets may be fitted into the concave portions of the two metal sheets, and the friction stir welding tool may be inserted into the metal foil sheets from above while rotating the friction stir welding tool. Furthermore, in step 2, the distance between the friction stir welding tool and the metal sheets may be in the range of 0.5 mm to 2.0 mm. The convex portion of the metal foil may be curved along the longitudinal direction of the metal foil, and the concave portion of the metal plate may be curved along the longitudinal direction of the metal plate.

[0021] In some embodiments, the current-carrying component for a secondary battery of the present invention includes a plurality of metal foil sheets stacked in the thickness direction and two metal plate sheets, the metal foil sheets having a base extending in the longitudinal direction and two protruding portions extending outward in the longitudinal direction from the base, the metal plate sheets having a recessed portion following the shape of the protruding portions of the metal foil sheets and a portion of different thickness, the metal foil sheets being placed above the thinner portions of the metal plate sheets, and the protruding portions of the metal foil sheets being fitted into the recessed portions of the metal plate sheets, and the two metal plate sheets being joined together at the locations where the protruding portions of the metal foil sheets are fitted into the recessed portions. Furthermore, the maximum width dimension of the protruding portions of the metal foil sheets can be longer than the width dimension of the boundary between the base and the protruding portions, which prevents the metal foil sheets from shifting when a joining tool is inserted and ensures a sufficient contact area between the metal foil sheets and the metal plate sheets. Furthermore, the joints between the metal plate and the metal foil may be formed at the locations where the metal plate and the metal foil are in contact in the longitudinal direction and the thickness direction, respectively. Furthermore, the number of metal foil sheets may be 10 or more, and each sheet may have a thickness of 0.21 mm or less. In this case, the metal foil sheet may be any metal foil sheet selected from the group consisting of aluminum, aluminum alloy, copper, and copper alloy.

[0022] In some embodiments, the method for manufacturing a secondary battery current-carrying component of the present invention is a method for manufacturing a secondary battery current-carrying component formed from two metal sheets and multiple metal foil sheets, the method comprising: a first step of joining the multiple metal foil sheets together by inserting a friction stir spot welding tool into the metal foil sheets while the multiple metal foil sheets are stacked in the thickness direction; a second step of cutting the periphery of the joint formed in the first step to form two convex portions extending outward in the longitudinal direction; and a third step of joining the metal sheets and the metal foil sheets by inserting the friction stir spot welding tool into the metal foil sheets while the thicker portions of the metal sheets have recesses that conform to the shapes of the convex portions of the metal foil sheets and fitting the convex portions of the metal foil sheets into the recesses. The maximum width of the convex portions of the metal foil sheets in the transverse direction can also be longer than the width of the boundary between the main body and the convex portions. The joints between the metal plate and the metal foil may be formed at the locations where the metal plate and the metal foil are in contact with each other in the longitudinal direction and the thickness direction. Furthermore, the number of metal foil sheets may be 10 or more, each sheet having a thickness of 0.21 mm or less, and the metal foil may be made of aluminum, an aluminum alloy, copper, or a copper alloy.

[0023] The present invention has the effect of being able to maintain a low electrical resistance value in a current-carrying component for a secondary battery manufactured by a friction stir spot joining method, even when the thickness of the welded portion is minimized.

[0024] Furthermore, in some embodiments, the present invention has the effect that a conductive component for a secondary battery manufactured by the friction stir spot joining method can be flexibly assembled to the secondary battery body and can maintain a low electrical resistance value.

[0025] Furthermore, in some embodiments, the present invention has the effect of maintaining a low electrical resistance value even in a configuration in which the thickness of the joint is minimized in an electrically conductive component for a secondary battery manufactured by the friction stir spot joining method, and ensuring a sufficient contact area between the metal foil material and the metal plate material.

[0026] Furthermore, in some embodiments, the manufacturing method for a secondary battery electrical component according to the present invention has the advantage that, in an electrical component for a secondary battery manufactured by a friction stir spot joining method, a low electrical resistance value can be maintained even in a configuration in which the thickness of the joint between the metal plate material and multiple metal foil materials is minimized, and a sufficient contact area can be ensured between the metal foil material and the metal plate material.

[0027] 1 is a schematic plan view of a current-carrying component 10 for a secondary battery according to a first embodiment of the present invention. It is a schematic front view of the current-carrying component 10 for a secondary battery according to the first embodiment of the present invention. It is a cross-sectional view taken along line A-A of the current-carrying component 10 for a secondary battery shown in FIG. 1. It is a schematic plan view of a metal sheet 2. It is a schematic front view of a metal sheet 2. It is a schematic plan view of a metal foil material 1. It is a schematic front view of a metal foil material 1. It is a schematic plan view of a current-carrying component 20 for a secondary battery according to a second embodiment of the present invention. It is a schematic front view of a current-carrying component 20 for a secondary battery according to the second embodiment of the present invention. It is a schematic plan view of a current-carrying component 210 for a secondary battery according to a third embodiment of the present invention. It is a schematic front view of a current-carrying component 210 for a secondary battery according to the third embodiment of the present invention. It is a cross-sectional view taken along line A-A of the current-carrying component 210 for a secondary battery shown in FIG. 10. It is a schematic front view of a metal sheet 202. It is a schematic plan view of a metal sheet 202. It is a schematic front view of a metal foil material 201. 1 is a schematic plan view of a metal foil material (first metal foil material) 201. FIG. 2 is a schematic plan view of a metal foil material (second metal foil material) 201. FIG. 3 is a schematic plan view of a secondary battery current-carrying component 220 according to a fourth embodiment of the present invention. FIG. 4 is a schematic front view of a secondary battery current-carrying component 220 according to the fourth embodiment of the present invention. FIG. 5 is a schematic cross-sectional view of a secondary battery current-carrying component 210 when subjected to a vertical load. FIG. 6 is a schematic cross-sectional view of a secondary battery current-carrying component 210 when subjected to a vertical load. FIG. 7 is a schematic cross-sectional view of a secondary battery current-carrying component 210 when subjected to a horizontal load. FIG. 8 is a schematic cross-sectional view of a secondary battery current-carrying component 230 according to the present invention. FIG. 9 is a schematic cross-sectional view of a secondary battery current-carrying component 230 according to the present invention during assembly. FIG. 10 is a schematic cross-sectional view of a secondary battery current-carrying component 310 according to a fifth embodiment of the present invention. FIG. 11 is a front view of a portion of a secondary battery current-carrying component 310 according to the fifth embodiment of the present invention. 28 is a cross-sectional view of the current-carrying component 310 for a secondary battery taken along line A-A in FIG. 27. FIG. 29 is a plan view of a metal plate 302A (302). FIG. 30 is a front view of a metal plate 302A (302). FIG. 31 is a plan view of a metal plate 302B (302) of a different embodiment. FIG. 32 is a front view of a metal plate 302B (302) of a different embodiment. FIG. 33 is a plan view of a metal foil material 301. FIG. 34 is a front view of a metal foil material 301. FIG. 35 is a plan view of a current-carrying component 320 for a secondary battery during a joining process. FIG. 36 is a plan view of a current-carrying component 320 for a secondary battery during a joining process.45. A plan view of a portion of a current-carrying component 330 for a secondary battery according to a sixth embodiment. A cross-sectional view of the B-B line of the current-carrying component 330 for a secondary battery shown in FIG. 38. A plan view of a metal sheet 322 according to a sixth embodiment. A front view of a metal sheet 322 according to a sixth embodiment. A plan view of a metal foil material 321 according to a sixth embodiment. A front view of a metal foil material 321 according to a sixth embodiment. A plan view of a current-carrying component 410 for a secondary battery manufactured using a manufacturing method according to a seventh embodiment of the present invention. A front view of the current-carrying component 410 for a secondary battery shown in FIG. 45. A cross-sectional view of the A-A line of the current-carrying component 410 for a secondary battery shown in FIG. 45. A plan view of a metal sheet 402A (402). A front view of a metal sheet 402A (402). A plan view of a metal sheet 402B (402) according to an eighth embodiment. A front view of a metal sheet 402B (402) according to an eighth embodiment. A plan view of a metal foil material 401 after joining (first step). 52 is a front view of the metal foil material 401 shown in FIG. 51 after joining (first step). FIG. 53 is a plan view of the metal foil material 401 after cutting (second step). FIG. 54 is a front view of the metal foil material 401 shown in FIG. 53 after cutting (second step). FIG. 55 is a schematic plan view of a conventional current-carrying component 100 for a secondary battery. FIG. 56 is a schematic front view of a conventional current-carrying component 100 for a secondary battery. (a) is a schematic cross-sectional view showing a conventional joining configuration (before joining) of a metal foil material 111 and a metal plate material 113, and (b) is a schematic cross-sectional view showing a conventional joining configuration (after joining) of a metal foil material 111 and a metal plate material 113.

[0028] A current-carrying component for a secondary battery according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a schematic plan view of a current-carrying component for a secondary battery 10 according to the first embodiment of the present invention, Fig. 2 shows a schematic front view of the current-carrying component for a secondary battery 10, and Fig. 3 shows a cross-sectional view of the current-carrying component for a secondary battery 10 shown in Fig. 1 along line A-A.

[0029] 1 and 2, a current-carrying component for a secondary battery (first embodiment) 10 of the present invention is broadly formed of two metal plate materials 2, 3 and a plurality of metal foil materials 1 (1a to 1j). In the current-carrying component for a secondary battery 10 of the present invention, the two metal plate materials 2, 3 are spaced apart from each other, and ten metal foil materials 1a to 1j are disposed between them to bridge the two metal plate materials 2, 3, which have portions with different thicknesses (thin portions 2a, 3a and thick portions 2b, 3b).

[0030] 1 and 2, the left and right ends of the ten metal foil materials 1a to 1j and the ends of the two metal plate materials 2, 3 are joined to each other by a friction stir spot joining method at two joining portions 51, 52, with the ten metal foil materials 1a to 1j stacked above the thinner portions 2a, 3a of the two metal plate materials 2, 3. The joining portions 51, 52 have blind hole-shaped recesses 51a, 52a formed therein, as shown in Fig. 3, and the ten stacked metal foil materials 1a to 1j and the metal plate materials 2, 3 are solid-state joined (organically and morphologically integrated) to each other around these recesses 51a, 52a.

[0031] The joints in the two joints 51, 52 are formed in the longitudinal direction and the thickness direction of the current-carrying component 10. That is, as shown in Fig. 3, each joint is joined at two locations: boundary portions (first locations) 51b, 52b where the metal foil material and the metal plate material are laminated together in the thickness direction, and boundary portions (second locations) 51c, 52c where the metal foil material and the metal plate material contact each other in the longitudinal direction.

[0032] In each of the joints 51 and 52 shown in Figure 3, the boundary portions 51b and 52b where the metal foil material and the metal plate material are laminated together in the thickness direction and the boundary portions 51c and 52c where the metal foil material and the metal plate material contact each other in the longitudinal direction are shown as separate, distinct areas, but the joint may also be in a form in which the boundary portion 51b (52b) on the thickness direction side and the boundary portion 51c (52c) on the longitudinal direction side are partially connected.

[0033] Next, details of the metal foil material 1 (1a to 1j) and the metal sheets 2, 3 forming the current-carrying component for a secondary battery (first embodiment) 10 shown in Figures 1 to 3 will be described with reference to the drawings. A schematic plan view of the metal sheet 2 forming the current-carrying component for a secondary battery 10 according to the first embodiment of the present invention is shown in Figure 4, a schematic front view of the metal sheet 2 is shown in Figure 5, a schematic plan view of the metal foil material 1 (1a to 1j) is shown in Figure 6, and a schematic front view of the metal foil material 1 (1a to 1j) is shown in Figure 7.

[0034] As shown in Figures 4 and 5, the metal plate 2 has portions 2a and 2b of different thicknesses within the same plate, with a step d formed between them. In other words, the step d is the difference in size in the thickness direction between the thin portion 2a and the thick portion 2b. A recess c is provided on one end of the thick portion 2b that has the step d. The shape of the recess c may be a rectangular recess shape other than the curved shape shown in Figures 4 and 5.

[0035] As shown in Figures 6 and 7, the metal foil material 1 (1a to 1j) is formed by stacking multiple sheets of metal foil material in the thickness direction. Furthermore, both ends of the metal foil material 1 (1a to 1j) have protrusions e (e1, e2) in the longitudinal direction (the left-right direction in Figures 6 and 7). These protrusions e1, e2 are preferably shaped so that, when joined to the aforementioned metal plate material 2, they can fit into the recesses c, c of the two metal plate materials 2, 3 arranged on both the left and right sides as shown in Figures 1 to 3.

[0036] That is, when the shape of the recessed portion c of the metal plate 2 is rectangular, the shape of the protruding portions e at both ends of the metal foil material 1 (1a to 1h) is also rectangular. Also, when the shape of the recessed portion c of the metal plate 2 is curved, the shape of the protruding portions e (e1, e2) at both ends of the metal foil material 1 (1a to 1j) is also curved. Note that, although the embodiment of the metal foil material shown in Figures 6 and 7 shows a configuration in which 10 metal foil materials 1a to 1j are stacked, it is preferable that the number of stacked sheets be at least 10.

[0037] Next, a secondary battery current-carrying component (second embodiment) 20 of the present invention will be described with reference to the drawings. Fig. 8 shows a schematic plan view of the secondary battery current-carrying component 20 of the present invention, and Fig. 9 shows a schematic front view of the secondary battery current-carrying component 20 of the present invention. As in the first embodiment described above, the secondary battery current-carrying component (second embodiment) 20 of the present invention is formed in a form in which multiple metal foil materials 21 are stacked in the thickness direction and bridge the ends of two metal plate materials 22, 23.

[0038] 9, thin portions 22a, 23a are provided at the ends of the two metal plate materials 22, 23, separate from portions 22b, 23b having the original thickness. With a plurality of metal foil materials 21 stacked above the thin portions 22a, 23a, the plurality of metal foil materials 21 and the two metal plate materials 22, 23 are solid-state welded to each other by a friction stir spot welding method (joints 61, 62).

[0039] Next, a current-carrying component for a secondary battery according to a third embodiment of the present invention will be described with reference to the drawings. A schematic plan view of a current-carrying component for a secondary battery 210 according to the third embodiment of the present invention is shown in Fig. 10, a schematic front view of the current-carrying component for a secondary battery 210 is shown in Fig. 11, and a cross-sectional view of the current-carrying component for a secondary battery 210 shown in Fig. 10 taken along line A-A in Fig. 12.

[0040] <<Secondary Battery Conductor (Third Embodiment) 210>> A secondary battery conductive component (third embodiment) 210 of the present invention is broadly formed from two metal plates 202, 203 and a total of nine layers of metal foil material 201 (201a to 201i), as shown in Figures 10 and 11. In the secondary battery conductive component 210 of the present invention, the two metal plates 202, 203 are spaced apart from each other, and a total of nine layers of metal foil material 201a to 201j are stacked in the thickness direction between them to bridge the two metal plates 202, 203.

[0041] 10 and 11, the left and right ends of a total of nine layers of metal foil material 201a to 201i and the ends of two metal plate materials 202, 203 are joined to each other by a friction stir spot welding method at two joints 251, 252. Blind hole-shaped recesses 251a, 252a are formed in these joints 251, 252 as shown in Fig. 12, and the nine stacked layers of metal foil material 201a to 201i and metal plate materials 202, 203 are solid-state joined to each other (organically and morphologically integrated) around these recesses 251a, 252a.

[0042] <<Joints 251, 252>> The joints of these two joints 251, 252 are formed in the longitudinal and thickness directions of the secondary battery current-carrying component 210. That is, as shown in Fig. 12 , each joint is joined at three locations: first boundary portions 251b, 252b where the metal foil material and the metal plate material are stacked together in the thickness direction on the outer side of the secondary battery current-carrying component 210; second boundary portions 251c, 252c where the metal foil material and the metal plate material contact each other in the longitudinal direction; and third boundary portions 251d, 252d where the metal foil material and the metal plate material are stacked together in the thickness direction on the central side of the secondary battery current-carrying component 210. As shown in Fig. 12 , the formation of multiple joints between the metal foil materials further reduces the electrical resistance of the secondary battery current-carrying component 210.

[0043] In each of the joints 251, 252 shown in Figure 12, the three boundary portions 251b, 252b, 251d, 252d where the metal foil material and the metal plate material are stacked together in the thickness direction, and the boundary portions 251c, 252c where the metal foil material and the metal plate material contact each other in the longitudinal direction are shown as separate, distinct areas, but the joint may also be in a form in which the boundary portion 251b (252b), 251d (252d) on the thickness side of the secondary battery current-carrying component 210 and the boundary portion 251c (252c) on the longitudinal side of the secondary battery current-carrying component 210 are partially connected.

[0044] Next, details of the metal foil material 201 (201a to 201i) and the metal plate materials 202, 203 forming the current-carrying component for a secondary battery (third embodiment) 210 shown in Figures 10 to 12 will be described with reference to the drawings. Figure 13 shows a schematic front view of the metal plate material 202 forming the current-carrying component for a secondary battery 210 according to the third embodiment of the present invention, Figure 14 shows a schematic plan view of the metal plate material 202, Figure 15 shows a schematic front view of the metal foil material 201 (201a to 201i), Figure 16 shows a schematic plan view of the first metal foil material 201 (201a, 201c, 201e, 201g, 201i), and Figure 17 shows a schematic plan view of the second metal foil material 201 (201b, 201d, 201f, 201h).

[0045] <<Metal Plate 202>> As shown in Figures 13 and 14, the metal plate 202 forming part of the current-carrying component for a secondary battery has portions 202a and 202b of different thicknesses within the same plate, with a step d formed between them. In other words, the step d is the difference in thickness between the thin portion 202a and the thick portion 202b. Furthermore, a recess c is provided on one end of the thick portion 202b that has the step d. The shape of the recess c may be a rectangular recess shape in addition to the curved shape shown in Figures 13 and 14.

[0046] <<First and Second Metal Foil Materials 201a to 201j>> The metal foil material 201 (201a to 201i) forming part of the current-carrying component for a secondary battery is divided into first metal foil materials 201 (201a, 201c, 201e, 201g, 201i) extending in the longitudinal direction as shown in Fig. 16 and pairs of second metal foil materials 201 (201b, 201d, 201f, 201h) that are shorter in the longitudinal direction than the first metal foil material as shown in Fig. 17. The metal foil materials 201 (201a to 201i) are configured in a form in which the first metal foil material and pairs of second metal foil materials are alternately stacked, such as the first metal foil material 201i, the pair of second metal foil materials 201h, the first metal foil material 201g, etc., from the bottom as shown in Figs. 12 and 15.

[0047] That is, since the pair of second metal foil materials is separated into left and right sides (the metal plate material 202, 203 side) and stacked in a sandwiched state between the two first metal foil materials, the current-carrying component for a secondary battery of the present invention has a gap between the first metal foil material and the pair of second metal foil materials stacked in the thickness direction as shown in Figures 11 and 12. The main purpose of forming the gap between the first metal foil material and the pair of second metal foil materials is to provide flexibility in the thickness direction and longitudinal direction of the current-carrying component for a secondary battery, as will be described later, thereby facilitating assembly to a secondary battery component.

[0048] 16 and 17, the first and second metal foil members 201 (201a to 201i) have protrusions e (e1, e2) at both ends in the longitudinal direction (left-right direction in FIGS. 16 and 17). These protrusions e1, e2 are preferably shaped so that they can fit into the recesses c, c of the two metal plates 202, 3 arranged on both the left and right sides as shown in FIGS. 13 and 14 when joined to a metal plate. In other words, when the recess c of the metal plate 202 is rectangular, the protrusions e at both ends of the metal foil members 201 (201a to 201i) are also rectangular.

[0049] Furthermore, when the shape of the recess c of the metal plate 202 is curved, the shapes of the protrusions e (e1, e2) at both ends of the metal foil material 201 (201a to 201i) are also curved. Note that, although the embodiment of the metal foil material shown in Figures 12 and 15 shows a case where a total of nine layers of metal foil materials 201a to 201i are used, it is preferable that the number of layers be at least nine.

[0050] Next, a secondary battery current-carrying component (fourth embodiment) 220 of the present invention will be described with reference to the drawings. Fig. 18 shows a schematic plan view of the secondary battery current-carrying component 220 of the present invention, and Fig. 19 shows a schematic front view of the secondary battery current-carrying component 220 of the present invention. As in the third embodiment described above, the secondary battery current-carrying component (fourth embodiment) 220 of the present invention is formed in a form in which multiple metal foil materials 221 are stacked in the thickness direction and bridge the ends of two metal plate materials 222, 223.

[0051] 19, thin portions 222a, 223a are provided at the ends of the two metal plate materials 222, 223, separate from portions 222b, 223b having the original thickness. With a plurality of metal foil materials 221 stacked above the thin portions 222a, 223a, the plurality of metal foil materials 221 and the two metal plate materials 222, 223 are solid-state welded to each other by a friction stir spot welding method (joints 261, 262).

[0052] Next, the morphological changes of the secondary battery current-carrying components of the third and fourth embodiments of the present invention after assembly will be described with reference to the drawings. It is assumed that the secondary battery current-carrying components of the present invention are fixed to the secondary battery body with bolts or the like and are further subjected to loads from various directions. For example, we will explain the case where the secondary battery current-carrying component of the present invention is installed on the secondary battery body in a state stretched and contracted in the longitudinal (axial) direction. Schematic cross-sectional views of the secondary battery current-carrying component 210 of the present invention when subjected to a vertical load are shown in Figures 20 and 21, and schematic cross-sectional views of the secondary battery current-carrying component 210 of the present invention when subjected to a horizontal load are shown in Figures 22 and 23, respectively.

[0053] When the current-carrying device 210 for a secondary battery according to the third and fourth embodiments of the present invention is assembled in a stretched state to a secondary battery body and then receives vertical loads F1 and F2 on the metal foil material, compressive forces V1 and V2 are generated in the metal foil material and metal plate material, as shown in Figures 20 and 21. At this time, since the multiple sheets of metal foil material are stacked with gaps between them, the gaps between the metal foil materials collapse, allowing the vertical loads F1 and F2 received by the metal foil material to be absorbed by the ductility of the metal foil material itself.

[0054] Furthermore, when the secondary battery current-carrying component 210 of the third and fourth embodiments of the present invention is assembled to the secondary battery main body in a shrunk (compressed) state and then receives horizontal loads F11 and F12 on the metal foil material portion, as shown in Figures 22 and 23, since the metal foil material and metal plate material portions were subjected to compressive forces during assembly, these forces are offset by the horizontal loads F11 and F12, and the component returns to its original state where no load is applied.

[0055] Next, the process of assembling the secondary battery current-carrying components of the third and fourth embodiments of the present invention to the secondary battery body will be described with reference to the drawings. Schematic cross-sectional views of the process of assembling the secondary battery current-carrying component 230 of the present invention to the secondary battery body using fasteners such as bolts are shown in Figures 24 to 26, respectively. First, holes H1 and H2 for receiving fasteners such as bolts are pre-formed in metal plates 232 and 233 located at both ends of the secondary battery current-carrying component 230 of the present invention, as shown in Figure 24. With the secondary battery current-carrying component 230 stretched in advance, bolts B1 and B2 are passed through the holes H1 and H2 as shown in Figure 25 to position it.

[0056] At this time, compressive forces (compressive stresses) F21, F22 that tend to contract are temporarily generated in the metallic foil material 231. Thereafter, nuts N1, N2 are screwed onto the heads of bolts B1, B2, thereby completing the assembly of the secondary battery current-carrying component 230 (to the secondary battery body). Since gaps are formed between the metallic foil materials 231 that form the secondary battery current-carrying component 230, after assembly to the secondary battery body is complete, deformation and distortion of the metallic foil material 231 and the metallic plate materials 232, 233 are gradually eliminated due to the ductility of the metallic foil material 231 when absorbing the load applied to the secondary battery body.

[0057] Next, a current-carrying component for a secondary battery according to a fifth embodiment of the present invention will be described with reference to the drawings. Fig. 27 shows a plan view of a current-carrying component for a secondary battery 310 according to the fifth embodiment of the present invention, Fig. 28 shows a front view of the current-carrying component for a secondary battery 310, and Fig. 29 shows a cross-sectional view of the current-carrying component for a secondary battery 310 along line A-A shown in Fig. 27. Hereinafter, the current-carrying component for a secondary battery according to the present invention is composed of two metal plates (described below) and multiple metal foils stacked together, but only the portion (one side) where the metal plates and the metal foils are joined together will be described.

[0058] <Secondary Battery Conductor 310> A fifth embodiment of the present invention, a secondary battery conductive component 310 (fifth embodiment), is broadly formed from a metal plate 302 and multiple metal foil materials 301 (301a to 301j), as shown in Figures 27 to 29. The ends of the ten metal foil materials 301 (301a to 301j) and the end of the metal plate 302 are joined to each other at a joint 351 by a friction stir spot joining method, with the ten metal foil materials 301a to 301j stacked above a thinner portion 302a of the metal plate 302, as shown in Figures 27 to 29.

[0059] As shown in Figures 27 and 29, this joint 351 has blind hole-shaped recesses 351a formed therein, and around these recesses 351a, the ten stacked metal foil materials 301a to 301j and the metal plate material 302 are solid-state bonded (organically and morphologically integrated) to each other.

[0060] The joints in this joint 351 are formed in the longitudinal and thickness directions of the current-carrying component 310. That is, as shown in Fig. 29 , each joint is joined at two locations: a boundary portion (first location) 351b where the metal foil material and the metal plate material are laminated together in the thickness direction, and a boundary portion (second location) 351c where the metal foil material and the metal plate material come into contact in the longitudinal direction.

[0061] In the joint 351 shown in Figure 29, the boundary portion 351b where the metal foil material and the metal plate material are stacked together in the thickness direction and the boundary portion 351c where the metal foil material and the metal plate material contact each other in the longitudinal direction are shown as separate, distinct areas, but the joint may also be in a form in which the boundary portion 351b on the thickness direction side and the boundary portion 351c on the longitudinal direction side are partially connected.

[0062] Next, details of the metal foil material 301 (301a to 301j) and the metal plate material 302 forming the current-carrying component for a secondary battery (fifth embodiment) 310 shown in Figures 27 to 29 will be described with reference to the drawings. Figure 30 shows a plan view of the metal plate material 302A (302) forming the current-carrying component for a secondary battery 310 according to the fifth embodiment of the present invention, Figure 31 shows a front view of the metal plate material 302A (302), Figure 32 shows a plan view of the metal plate material 302B (302) according to a different embodiment (sixth embodiment), Figure 33 shows a front view of the metal plate material 302B (302) according to a different embodiment (sixth embodiment), Figure 34 shows a schematic plan view of the metal foil material 301 (301a to 301j), and Figure 35 shows a schematic front view of the metal foil material 301 (301a to 301j).

[0063] (Metal Plate 302) As shown in Figures 30 and 31, the metal plate 302A (302) has portions 302a and 302b of different thicknesses within the same plate, with a step d formed between them. In other words, the difference in thickness between the thin portion 302a and the thick portion 302b is the step 302d. In addition, a recess 302c is provided on one end of the thick portion 302b that has the step d. The recess 302c is provided to correspond to the shape of the protrusions formed on both ends of the metal foil material, which will be described later. Therefore, the shape of the recess 302c is formed in advance according to (copying) the shape of the protrusions of the metal foil material, which will be described later.

[0064] Furthermore, regarding the widthwise dimension of recess 302c (the vertical direction in FIG. 30), width dimension W11 at the boundary between thin portion 302a and thick portion 302b shown in FIG. 31 is smaller than maximum width dimension W12 of recess 302c. This is because, as described above, the shape of recess 302c is formed following the shape of the protrusions of the metal foil material described below, and therefore the widthwise dimension of the tip of the protrusions expands along the longitudinal direction.

[0065] Next, a sixth embodiment of the metal plate 302B (302) will be described. The metal plate 302B (302) of the embodiment shown in Figures 32 and 33 has a recess 302e and a step 302d formed by the recess 302e at one end, similar to the metal plate 302A (302) shown in Figures 30 and 31.

[0066] Furthermore, regarding the widthwise dimension of the recess 302e (the vertical direction in FIG. 32), the width dimension W21 at the end of the metal plate 302B (302) shown in FIG. 32 is smaller than the maximum width dimension W22 of the recess 302e. This is because the shape of the recess 302e is formed following the shape of the convex portion of the metal foil material described below, and the widthwise dimension of the tip of the convex portion expands along the longitudinal direction.

[0067] On the other hand, unlike the metal plate 302A (302) shown in Figures 30 and 31, the metal plate 302B (302) of the sixth embodiment is not divided into thin and thick parts in the longitudinal direction (left and right direction in Figures 32 and 33) of the same metal plate 302B (302) as shown in Figures 32 and 33, and the overall thickness is uniform.

[0068] (Metal foil material 301) As shown in Figures 34 and 35, the metal foil material 301 (301a to 301j) is formed by stacking multiple sheets of metal foil material in the thickness direction. Each metal foil material 301 (301a to 301j) has a base 301C located in the center and protrusions e (e1, e2) formed on both ends of the base 301C in the longitudinal direction (the left-right direction in Figures 34 and 35). These protrusions e1, e2 are shaped so that, when joined to the aforementioned metal plate material 302, they can fit into recesses 302c, 302e of metal plates 302A, 302B located on one end side, as shown in Figures 27 to 29.

[0069] Regarding the width direction (vertical direction in FIG. 34 ) of the convex portions e (e1, e2), the maximum width dimension W2 at the convex portions e (e1, e2) is larger than the width dimension W1 at the boundary portion 301B between the base portion 301C and the convex portions e (e1, e2). In other words, the width dimension W1 at the boundary portion 301B between the base portion 301C and the convex portions e (e1, e2) is made smaller than the maximum width dimension W2 of the convex portions e (e1, e2). Note that while the metal foil material 301 shown in FIGS. 34 and 35 shows a case in which ten metal foil materials 301a to 301j are stacked, the number of stacked sheets is not limited to ten and can be any number, such as nine or less, eleven or more, etc.

[0070] <Secondary Battery Current-Carrying Component 330> Next, a sixth embodiment of the present invention will be described with reference to the drawings. Fig. 38 shows a plan view of the sixth embodiment of the present invention, the second battery current-carrying component 330, and Fig. 39 shows a cross-sectional view of the second battery current-carrying component 330 shown in Fig. 38 along line B-B. As in the fifth embodiment, the second battery current-carrying component of the present invention is composed of two metal plates (described below) and multiple metal foils laminated together. However, only the portion (one side) where the metal plates and the metal foils are joined together will be described below.

[0071] 38 and 39, the secondary battery current-carrying component (sixth embodiment) 330 of the present invention is broadly formed from a metal plate material 322 and multiple metal foil materials 321 (321a, 321b, 321c...). The ends of the multiple metal foil materials 321 (321a, 321b, 321c...) and the end of the metal plate material 322 are joined to each other at two joining portions 371, 372 by a friction stir spot joining method, with the multiple metal foil materials 321a, 321b, 321c... stacked above the thinner portion 322a of the metal plate material 322, as shown in FIG.

[0072] As shown in Figure 39, these joints 371, 372 have blind hole-shaped recesses 371a formed therein, and around these recesses 371a, multiple laminated metal foil materials 321a, 321b, 321c, etc. and metal plate material 322 are solid-state bonded (organically and morphologically integrated) to each other.

[0073] The joints in each joint 371 are formed in the longitudinal and thickness directions of the current-carrying component 330. That is, as shown in Fig. 39 , each joint is joined at two locations: a boundary portion (first location) 371b where the metal foil material and the metal plate material are laminated together in the thickness direction, and a boundary portion (second location) 371c where the metal foil material and the metal plate material come into contact in the longitudinal direction.

[0074] In the joint 371 shown in Figure 39, the boundary portion 371b where the metal foil material and the metal plate material are stacked together in the thickness direction and the boundary portion 371c where the metal foil material and the metal plate material contact each other in the longitudinal direction are shown as two separate, distinct areas, but the joint may also be in a form in which the boundary portion 371b on the thickness direction side and the boundary portion 371c on the longitudinal direction side are partially connected.

[0075] Next, details of the metal foil material 321 (321a, 321b, 321c, ...) and the metal plate material 322 that form the current-carrying component for a secondary battery (sixth embodiment) 330 shown in Figures 38 and 39 will be described with reference to the drawings. A plan view of the metal plate material 322 that forms the current-carrying component for a secondary battery 330 according to the sixth embodiment of the present invention is shown in Figure 40, a front view of the metal plate material 322 is shown in Figure 41, a schematic plan view of the metal foil material 321 is shown in Figure 42, and a schematic front view of the metal foil material 321 is shown in Figure 43.

[0076] (Metal Plate 322) A plan view of a metal plate 322 forming a secondary battery current-carrying component (sixth embodiment) 330 according to the sixth embodiment is shown in Fig. 40, and a front view of the metal plate 322 according to the sixth embodiment is shown in Fig. 41. As shown in Figs. 40 and 41, the metal plate 322 has portions 322a and 322b of different thicknesses within the same plate, and a step 322d is formed between the portions.

[0077] That is, the difference in dimension in the thickness direction between the thin portion 322a and the thick portion 322b is the step 322d. Also, a recess 322c is provided on one end side of the thick portion 322b that has the step 322d. The recess 322c is provided to correspond to the shape of the protrusions formed on both ends of the metal foil material, which will be described later. Therefore, the shape of the recess 322c is formed in advance according to (copying) the shape of the protrusions of the metal foil material, which will be described later.

[0078] Furthermore, regarding the widthwise dimension of recess 322c (the vertical direction in FIG. 40), width dimension W31 at the boundary between thin portion 322a and thick portion 322b shown in FIG. 41 is smaller than maximum width dimension W32 of recess 322c. This is because, as described above, the shape of recess 322c is formed following the shape of the protrusions of the metal foil material described below, and therefore the widthwise dimension of the tip of the protrusions expands along the longitudinal direction.

[0079] (Metal foil material 321) Fig. 42 is a plan view of a metal foil material 321 according to a sixth embodiment of the present invention, which forms part of a current-carrying component 330 for a secondary battery according to the sixth embodiment of the present invention, and Fig. 43 is a front view of the metal foil material 321 according to the sixth embodiment. As shown in Figs. 42 and 43, the metal foil material 321 has a configuration in which a plurality of metal foil materials are laminated in the thickness direction.

[0080] The metal foil material 321 has a base 321C disposed in the center and protrusions e21, e22 formed in the longitudinal direction (left-right direction in FIGS. 42 and 43) at both ends of the base 321C. These protrusions e21, e22 are shaped so that when joining to the metal plate 322 described above, they can fit into the recess 322c of the metal plate 322 disposed on one end side as shown in FIGS.

[0081] Regarding the widthwise dimension (vertical direction in FIG. 42 ) of the protrusions e21 and e22, the maximum width dimension W42 of the protrusions e21 and e22 is larger than the width dimension W41 at the boundary 321B between the base 321C and the protrusions e21 and e22. In other words, the width dimension W41 at the boundary 321B between the base 321C and the protrusions e21 and e22 is made smaller than the maximum width dimension W42 of the protrusions e21 and e22.

[0082] Note that the metal foil material 321 shown in Figures 39 and 43 shows a case in which 10 sheets of metal foil material are stacked together, but the number of sheets to be stacked is not limited to 10, and can be set as desired, such as 9 sheets or less, or 11 sheets or more.

[0083] Next, a seventh embodiment of the present invention will be described. This seventh embodiment of the present invention relates to a method for manufacturing a secondary battery current-carrying component, and in particular, to a method for efficiently and accurately manufacturing a current-carrying component using two metal plates and multiple metal foils. In this manufacturing method, multiple metal foils are first stacked in the thickness direction and then joined from the outermost surface of the metal foils in the thickness direction using a friction stir spot welding tool (hereinafter referred to as the "first step").

[0084] That is, in the first step, a friction stir spot welding tool is inserted from above the outermost surface of the metal foil material in the thickness direction to reliably join the multiple metal foil materials together, thereby forming a laminate of metal foil materials.

[0085] Next, the laminate of metal foil materials is processed around the joining point (hereinafter referred to as the "second step"). In the second step, the metal foil material is cut around the joining point into two convex shapes that protrude outward in the longitudinal direction. This cutting step improves the joining strength of the metal foil material and also forms the shape required for joining with the subsequent metal plate material. This prepares the metal foil material and the metal plate material for precise fitting.

[0086] Next, in the process of joining the metal plate and the metal foil (hereinafter referred to as the "third process"), the metal plate has portions of different thicknesses, and the thicker portions have recesses that follow the shape of the protrusions on the metal foil. In the third process, the protrusions on the metal foil are fitted into the recesses, and a friction stir spot joining tool is used to firmly join the metal plate and the metal foil. This results in the integral formation of the shape and structure required for a current-carrying component for a secondary battery.

[0087] In a seventh embodiment of the present invention, the maximum dimension in the short-side direction of the protrusion of the metal foil material is set to be longer than the short-side dimension at the boundary between the main body and the protrusion. This improves the bonding strength of the protrusion and ensures the structural strength of the entire current-carrying component. Furthermore, the bonding points between the metal plate material and the metal foil material are formed at the locations where the two materials are in contact in the longitudinal direction and the thickness direction. This bonding method (manufacturing method) further increases the bonding strength and improves electrical and mechanical reliability.

[0088] Furthermore, in the manufacturing method of the seventh embodiment of the present invention, ten or more sheets of metal foil material are used, and the thickness of each sheet is 0.21 mm or less, thereby reducing the weight and improving the flexibility of the current-carrying component. The material of the metal foil material is selected from aluminum, aluminum alloy, copper, and copper alloy. These materials have high electrical conductivity and are suitable for current-carrying components for secondary batteries.

[0089] Next, a secondary battery current-carrying component manufactured using the manufacturing method of the seventh embodiment of the present invention will be described with reference to the drawings. Fig. 44 shows a plan view of a secondary battery current-carrying component 410 manufactured using the manufacturing method of the seventh embodiment of the present invention, Fig. 45 shows a front view of the same secondary battery current-carrying component 410, and Fig. 46 shows a cross-sectional view of the secondary battery current-carrying component 410 shown in Fig. 44 along line A-A. Hereinafter, the secondary battery current-carrying component of the present invention is composed of two metal plates (described below) and multiple metal foils stacked together, but only the portion (one side) where the metal plates and metal foils are joined to each other will be described.

[0090] <Secondary Battery Conductor 410> As shown in Figures 44 to 46, a secondary battery conductive component 410 (seventh embodiment) of the present invention is broadly formed from two metal plate materials 402, 402 and a metal foil material 401. The end of the metal foil material 401 and the end of the two metal plate materials 402, 402 are joined to each other at a joint 451 by a friction stir spot joining method, with the metal foil material 401 stacked above the thinner portions 402a of the metal plate materials 402, 202, as shown in Figures 44 to 46.

[0091] 44 and 46, the joint 451 has a blind-hole-shaped recess 451a formed therein, and the laminated metal foil material 401 and metal plate materials 402, 402 are solid-state welded (organically and morphologically integrated) around the recess 451a. The joint 451 has two joining locations, one in the longitudinal direction and the other in the thickness direction of the current-carrying component 410 for a secondary battery. That is, as shown in FIG. 46, each joint is joined at two locations: a boundary (first location) 451b where the metal foil material and the metal plate material are laminated together in the thickness direction, and a boundary (second location) 451c where the metal foil material and the metal plate material come into contact in the longitudinal direction.

[0092] In the joint 451 shown in Figure 46, the boundary portion 451b where the metal foil material and the metal plate material are stacked together in the thickness direction and the boundary portion 451c where the metal foil material and the metal plate material contact each other in the longitudinal direction are shown as two separate, distinct areas, but the joint may also be in a form in which the boundary portion 451b on the thickness direction side and the boundary portion 451c on the longitudinal direction side are partially connected.

[0093] Next, details of the metal foil material 401 and the metal plate material 402 forming the current-carrying component 410 for a secondary battery shown in Figures 44 to 46 will be described with reference to the drawings. Figure 47 shows a plan view of a metal plate material 402A (402) forming the current-carrying component 410 for a secondary battery of the present invention, Figure 48 shows a front view of the metal plate material 402A (402), Figure 49 shows a plan view of a metal plate material 402B (402) of an eighth embodiment, Figure 50 shows a front view of the metal plate material 402B (402) of the eighth embodiment, Figure 51 shows a plan view of the metal foil material 401 after joining (first step), Figure 52 shows a front view of the metal foil material 401 shown in Figure 51 after joining (first step), Figure 53 shows a plan view of the metal foil material 401 after cutting (second step), and Figure 54 shows a front view of the metal foil material 401 shown in Figure 53 after cutting (second step).

[0094] (Metal Plate 402) As shown in Figures 47 and 48, the metal plate 402A (402) has portions 402a and 402b of different thicknesses within the same plate, with a step 402d formed between them. In other words, the step 402d is the difference in thickness between the thin portion 402a and the thick portion 402b. In addition, a recess 402c is provided on one end of the thick portion 402b that has the step 402d. The recess 402c is provided to correspond to the shape of the protrusions formed on both ends of the metal foil material, which will be described later. Therefore, the shape of the recess 402c is formed in advance according to (copying) the shape of the protrusions of the metal foil material, which will be described later.

[0095] Furthermore, regarding the widthwise dimension of recess 402c (the vertical direction in FIG. 47), width dimension W11 at the boundary between thin portion 402a and thick portion 402b shown in FIG. 48 is smaller than maximum width dimension W12 of recess 402c. This is because, as described above, the shape of recess 402c is formed following the shape of the protrusions of the metal foil material described below, and therefore the widthwise dimension of the tip of the protrusions expands along the longitudinal direction.

[0096] Next, a description will be given of a metal plate 402B (402) according to an eighth embodiment. The metal plate 402B (402) according to the embodiment shown in Figures 49 and 50 has a recess 402e and a step 402d formed by the recess 402e at one end, similar to the metal plate 402A (402) shown in Figures 47 and 48.

[0097] Furthermore, regarding the widthwise dimension of the recess 402e (the vertical direction in FIG. 49), the width dimension W21 at the end of the metal plate 402B (402) shown in FIG. 49 is smaller than the maximum width dimension W22 of the recess 402e. This is because the shape of the recess 402e is formed following the shape of the convex portion of the metal foil material described below, and the widthwise dimension of the tip of the convex portion widens along the longitudinal direction.

[0098] On the other hand, unlike the metal plate 402A (402) shown in Figures 47 and 48, the metal plate 402B (402) of the eighth embodiment is not divided into thin and thick parts in the longitudinal direction (left and right direction in Figures 49 and 50) of the same metal plate 402B (402) as shown in Figures 49 and 50, and the overall thickness is uniform.

[0099] (Metal foil material 401) The metal foil material 401 is formed by stacking multiple sheets of metal foil material in the thickness direction, and integrating each foil material by a friction stir spot joining method, as shown in Figures 51 to 54. The metal foil material 401 is produced by firstly stacking multiple sheets of metal foil material in the thickness direction, as shown in Figures 51 and 52, and then inserting a friction stir spot joining tool into the metal foil material to join the multiple sheets of metal foil material together (first step).

[0100] Then, in a second step, the area around the joint formed in the first step is cut to form two protrusions that extend outward in the longitudinal direction, so that the metal foil material 401 has a base 401C located in the center as shown in Figures 53 and 54, and protrusions e1 and e2 formed at both ends of the base 401C in the longitudinal direction (left and right directions in Figures 53 and 54).

[0101] These protrusions e1, e2 are shaped so that when joining the two metal plates 402, 402 mentioned above, they can fit into the recesses 402c, 402e of the metal plates 402A, 402B located on one end side as shown in Figures 47 to 50.

[0102] Regarding the widthwise dimension (vertical direction in FIG. 53) of the protrusions e1 and e2, the maximum width dimension W2 of the protrusions e1 and e2 is larger than the width dimension W1 at the boundary 401B between the base 401C and the protrusions e1 and e2. In other words, the width dimension W1 at the boundary 401B between the base 401C and the protrusions e1 and e2 is made smaller than the maximum width dimension W2 of the protrusions e1 and e2.

[0103] If the metal foil material is aluminum or an aluminum alloy, the thickness may be 0.2 mm or less (JIS H4160, H4170), and if the metal foil material is copper or a copper alloy, the thickness may be 0.21 mm or less (JIS C6515).

[0104] Next, we will explain the results of conducting current tests and compression tests on some of the above embodiments and comparing them with conventional products. The conventional product is the conventional secondary battery current-carrying component 100 described in Figures 55 and 56. Furthermore, the secondary battery current-carrying component 10 of the first embodiment described above (see Figures 1 to 7) is Example 1, and the secondary battery current-carrying component 410 of the seventh embodiment (see Figures 44 to 54) is Example 2.

[0105] The dimensions of the conventional example and the embodiment are expressed according to the following definitions. When the current-carrying component 100 for a secondary battery is placed as shown in Figure 55, the left-right direction as seen in Figure 55 is defined as the "connection direction of the product (component)". When the current-carrying component 100 for a secondary battery is placed as shown in Figure 55, the up-down direction as seen in Figure 55 is defined as the "width direction of the product (component)". When the current-carrying component 100 for a secondary battery is placed as shown in Figure 56, the up-down direction as seen in Figure 56 is defined as the "thickness direction of the product (component)".

[0106] According to the above definitions, the dimensions of the comparative example and the example are as follows. <Comparative Example> Metal plate materials 102, 103: Length in the connection direction 50 mm, length in the width direction 20 mm, length in the thickness direction 4 mm. Material: copper. Metal foil material 101: Length in the connection direction 110 mm, length in the width direction 20 mm, length in the thickness direction 0.10 mm. Material: copper. Number of laminated sheets of metal foil material 101: 40 sheets Current-carrying component 100 for a secondary battery: Overall length in the connection direction (length from the right end of metal plate material 102 to the left end of metal plate material 103 in FIG. 55 ) was 170 mm Distance between joint points (distance between the center of the circle of right joint location 151 and the center of the circle of left joint location 152 in FIG. 55 ): 90 mm Diameter of joint holes (diameter of holes at joint locations 151, 152 in FIG. 55 ): 6 mm Distance between bolt points (distance between the centers of bolt holes (see holes H1, H2 in FIG. 24 ) provided in metal plate materials 102, 103): 150 mm Diameter of bolt fastening hole (see holes H1, H2 in FIG. 24 ): 6.5 mm Example 1 (see FIGS. 1 to 7 ) Metal plates 2, 3: Length in the connection direction: 50 mm, length in the width direction: 20 mm, length in the thickness direction: 5 mm, and step d (see FIG. 5) was 4 mm. Made of copper. Metal foil material 1: Total length in the connection direction: 98 mm, total length in the width direction: 20 mm, and length in the thickness direction: 0.10 mm. Made of copper. Number of laminated metal foil materials 1: 40 sheets. Secondary battery current-carrying component 10: Total length in the connection direction: 170 mm. Distance between joining points: 90 mm. Diameter of joining hole: 6 mm. Distance between bolt points: 150 mm. Diameter of bolt fastening hole: 6.5 mm. Example 2 (see FIGS. 44 to 54). Metal plates 402, 403: Length in the connection direction: 50 mm, length in the width direction: 20 mm, length in the thickness direction: 5 mm, and step 402d (see FIG. 48) was 4 mm. Made of copper. Metal foil material 401: Total length in the connection direction is 98 mm, total length in the width direction is 20 mm, and length in the thickness direction is 0.10 mm. Material: copper. Number of layers of metal foil material 401: 40 sheets. Current-carrying component for secondary battery: Total length in the connection direction is 170 mm. Distance between joint points: 90 mm. Diameter of joint hole: 6 mm. Distance between bolt points: 150 mm. Diameter of bolt fastening hole: 6.5 mm

[0107] The current test measures the voltage (V) and temperature rise (°C) when current is applied under the following current condition 1 and current condition 2. Current condition 1: Apply a current of 800 amperes for 300 seconds. Current condition 2: Apply a current of 1000 amperes for 30 seconds.

[0108] The purpose of the electrical conduction test is as follows. In the comparative example, the thickness of the overlapping portion between the metal plates 102, 103 and the metal foil material 1 is 8 mm (the sum of the 4 mm thickness of the metal plates 102, 103 and the 4 mm thickness of the 40 sheets of metal foil material 1). In contrast, if the thickness of the secondary battery current-carrying component is reduced to 5 mm (the sum of the 1 mm thickness of the thin portions 2a, 3a of the metal plates and the 4 mm thickness of the 40 sheets of metal foil material 1) as in Examples 1 and 2, it is inevitable that the electrical resistance value will increase and the heat generation will increase. The purpose of the electrical conduction test was to confirm whether the increase in electrical resistance value and the temperature rise due to heat generation are comparable to those of conventional products, even when the overall thickness is made compact and thin. The results of the electrical conduction test are shown in Table 1.

[0109]

[0110] In the comparative example, the thickness of the overlapping portion between the metal plates 102, 103 and the metal foil material 1 is 8 mm, while in examples 1 and 2, the thickness is a compact 5 mm. Therefore, although the electrical resistance values ​​of examples 1 and 2 are higher than those of the comparative example, the increase is very small, at a maximum of 0.0037 milliohms. Furthermore, the temperature rise due to heat generation is also limited to a maximum of 20.2°C, a difference of only 2.1°C compared to the conventional comparative example. These results confirm that even in products with reduced thicknesses at the joint between the metal plate and the metal foil material, as in examples 1 and 2, low electrical resistance values ​​comparable to those of conventional products can be maintained. Furthermore, it was confirmed that the connection configuration of example 2 has a slight advantage over the connection configuration of example 1 in terms of the joint configuration between the metal plate and the metal foil material.

[0111] Next, a compression test will be described. It is assumed that the current-carrying component for a secondary battery is fixed to the secondary battery body with bolts or the like and then subjected to loads from various directions (see the explanations of FIGS. 20 to 26 ). The purpose of the compression test is to confirm whether the flexibility of the current-carrying component for a secondary battery is comparable to that of the current-carrying component for a secondary battery, even when the shape of the joint between the metal plate material and the metal foil material is changed as in the present invention.

[0112] The compression test measures the load (N) generated by the testing machine when the bolts (see bolts B1 and B2 in FIG. 25) that secure the current-carrying component to the battery body are moved a predetermined distance in the left-right direction (the connection direction defined above in this specification) so as to approach each other. The results of the compression test are shown in Table 2.

[0113]

[0114] As shown in Table 2, even when a stroke of 1 mm was applied, the load generated in Examples 1 and 2 was less than 50 Newtons, demonstrating flexibility comparable to that of conventional comparative examples. This confirms that even when the thickness of the joint between the metal plate material and the metal foil material is reduced as in the present invention, it is possible to manufacture a current-carrying part for a secondary battery that maintains flexibility. It was also confirmed that the connection configuration of Example 1 is slightly superior to the connection configuration of Example 2 in terms of flexibility.

[0115] 1: Metal foil material, 2, 3: Metal plate material, 10, 20: Current-carrying part for secondary battery, 21: Metal foil material, 22, 23: Metal plate material, 51, 52: Joint portion, 61, 62: Joint portion, 201: Metal foil material, 202, 203: Metal plate material, 210, 220, 230: Current-carrying part for secondary battery, 221, 231: Metal foil material, 222, 223, 232, 233: Metal plate material, 251, 252: Joint portion, 261, 262: Joint portion, 301 (301a to 301j): Metal foil material, 301B: Boundary portion, 301C: Base portion, 302 (302A, 302B): Metal plate material, 303: Metal plate material, 302a: Thin portion of metal plate, 302b: Thick portion of metal plate, 302c, 302e: Recessed portion, 302d: Step, 310, 320: Current-carrying part for secondary battery, 321: Metal foil material, 321a to 321c: Metal foil material, 321B: Boundary portion, 321C: Base portion, 322, 323: Metal plate, 322a: Thin portion of metal plate, 322b: Thick portion of metal plate, 322c: Recessed portion, 322d: Step, 330: Current-carrying part for secondary battery, 351, 352: Joint portion, 351a: Recessed portion, 351b, 351c: Boundary portion, 361, 362: Joint portion, 371, 372: Joint portion, 371a: Recessed portion, 371b, 371c: boundary portion, 401: metal foil material, 401B: boundary portion, 401C: base portion, 402 (402A, 402B): metal plate material, 402a: thin portion of metal plate material, 402b: thick portion of metal plate material, 402c, 402e: recessed portion, 402d: step, 410: current-carrying component for secondary battery, 451, 452: joint portion, 451a: recessed portion, 451b, 451c: boundary portion, d: step, e (e1, e2): convex portion, e21, e22: convex portion, W1, W11: width dimension of boundary portion, W2: maximum width dimension of convex portion, W12: maximum width dimension of recessed portion, W21: width dimension of end portion of metal plate material, W22: maximum width dimension of recessed portion, W31: width dimension of boundary portion, W32: maximum width of recess, W41: width of boundary, W42: maximum width of protrusion

Claims

1. A current-carrying component for a secondary battery comprising multiple sheets of metal foil material and two sheets of metal plate material, wherein the metal plate material has portions of different thicknesses, and the multiple sheets of metal foil material and the two sheets of metal plate material are joined together in a state where the multiple sheets of metal foil material are stacked above the thinner portions of the metal plate material.

2. An electrical component for a secondary battery as described in claim 1, characterized in that the points where the metal plate material and the metal foil material are joined are formed at points where the metal plate material and the metal foil material are in contact in the longitudinal direction and thickness direction, respectively.

3. An electrical component for a secondary battery as described in claim 2, characterized in that the sum of the thicknesses of the thin portions of the plurality of metal foil materials and the metal plate material is the same as the thickness of the thick portions of the metal plate material.

4. The current-carrying component for a secondary battery according to claim 3, characterized in that the number of said metal foil materials is 10 or more, and the thickness of each of said metal foil materials is 0.21 mm or less.

5. A current-carrying component for a secondary battery according to any one of claims 1 to 4, characterized in that the metal foil material is one of aluminum, aluminum alloy, copper, and copper alloy.

6. A current-carrying component for a secondary battery described in any one of claims 1 to 4, characterized in that the metal foil material is formed from at least two sheets of first metal foil material extending in the longitudinal direction and two sheets of second metal foil material having a longitudinal length shorter than that of the first metal foil material, the two sheets of second metal foil material being separated into left and right sides and stacked in a state sandwiched between the two sheets of first metal plate material, and the first and second metal foil materials are placed above the thinner parts of the metal plate material, with both left and right ends of the first and second metal foil materials joined to the two metal plate materials.

7. A current-carrying component for a secondary battery as described in any one of claims 1 to 4, characterized in that the metal foil material has a base extending in the longitudinal direction and two convex portions that protrude outward in the longitudinal direction from the base, the metal plate material has a concave portion that follows the shape of the convex portions of the metal foil material, and when the metal foil material is placed above the thinner part of the metal plate material and the convex portions of the metal foil material are fitted into the concave portions of the metal plate material, the two metal plates are joined to each other at the points where the convex portions of the metal foil material are fitted into the concave portions of the metal plate material.

8. An electrical conducting component for a secondary battery as described in claim 7, characterized in that the longest dimension in the width direction of the convex portion of the metal foil material is longer than the dimension in the width direction at the boundary between the base and the convex portion.

9. A method for manufacturing an electrical component for a secondary battery as described in claim 1, comprising the steps of: a first step of using two metal plate materials having portions of different thicknesses and a plurality of metal foil materials, stacking the plurality of metal foil materials above the thinner portions of the metal plate materials; a second step of inserting the friction stir welding tool into the metal foil materials from above while rotating the friction stir welding tool after the first step; and a third step of removing the friction stir welding tool from within the metal foil materials after the second step.

10. A method for manufacturing an electrical component for a secondary battery as described in claim 9, characterized in that in the first step, both ends of the plurality of metal foil materials are further provided with convex portions protruding along the longitudinal direction, and one end of the two metal plate materials is further provided with concave portions along the longitudinal direction, and the convex portions of the plurality of metal foil materials are fitted into the concave portions of the two metal plate materials.

11. A method for manufacturing an electrical component for a secondary battery as described in claim 10, characterized in that the convex portion has a curved shape that follows the longitudinal direction of the metal foil material, and the concave portion has a curved shape that follows the longitudinal direction of the metal plate material.

12. A method for manufacturing an electrical component for a secondary battery as described in claim 9, characterized in that in the second step, the distance from the tip of the friction stir welding tool to the edge of the metal plate material is in the range of 0.5 mm or more and 2.0 mm or less.

13. A method for manufacturing an electrical component for a secondary battery as described in claim 1, comprising: a first step of joining multiple sheets of metal foil material together by inserting the friction stir spot welding tool into the metal foil material from above while the multiple sheets of metal foil material are stacked in the thickness direction; a second step of cutting the metal foil material around the joining point into two convex shapes that protrude outward in the longitudinal direction; and a third step of inserting the friction stir spot welding tool into the metal foil material with the convex parts of the metal foil material fitted into the concave parts in the thicker parts of the metal plate material, thereby joining the metal plate material and the metal foil material.