WO2024117009A1 - Conductive component for secondary battery, and manufacturing method thereof - Google Patents

Abstract

Provided are: a conductive component which is for a secondary battery and is capable of being bonded without affecting other components even when the conductive component is attached to other components such as an electrode material using a bonding method such as laser welding; and a method for manufacturing said conductive component. The conductive component 100 for a secondary battery is formed from a plurality of foil materials 10, 20, 30 made of aluminum or aluminum alloy. After these plurality of foil materials 10, 20, and 30 are laminated in the thickness direction, the foil materials 10, 20, and 30 adjacent to each other in the thickness direction are bonded to each other by friction stir point welding to form recessed parts 11 and 12.

Description

Current-carrying component for secondary battery and method of manufacturing same

The present invention relates to current-carrying components for secondary batteries, primarily installed in automobiles, and methods for manufacturing the same.

Current-carrying components formed from two or more sheets or foils, particularly those used in secondary batteries in automobiles, are also called bus bars, and technology has been disclosed for forming them from highly conductive materials such as aluminum alloys and copper alloys (see Patent Document 1).

Japanese Patent No. 6971990

However, when multiple sheets of metal foil material are laminated and then joined to an electrode material underneath using laser welding or the like, the heat and vibrations from the laser welding or the like have difficulty reaching the metal foil material underneath, so there is a problem in that it is not possible to join the current-carrying component formed from multiple sheets of metal foil material to the electrode material. Even if joining can be achieved using high-power laser welding or the like, there is still the problem of the electrode material underneath being affected by deformation and other effects caused by excessive heat and vibration.

The present invention aims to provide a current-carrying component for a secondary battery that can be joined to other components, such as electrode materials, without affecting the other components, even when the component is attached (joined) to the other components using a joining method such as laser welding, and a method for manufacturing the same.

The current-carrying component for a secondary battery of the present invention is formed from multiple sheets of aluminum or aluminum alloy foil material. These multiple sheets of foil material are stacked in the thickness direction, and adjacent foil sheets in the thickness direction of the foil material are joined by friction stir spot welding. In addition, there may be five or more sheets of these foil materials, and the thickness of each foil material may be 0.5 mm or less. Furthermore, the foil material may be further provided with a bent portion in which it is bent in a straight or curved shape.

In addition, in the invention of the manufacturing method for the current-carrying component for the secondary battery, first, multiple sheets of aluminum or aluminum alloy foil material are stacked, and then a plate material of the same composition as these foil materials is placed on the top layer (first step). After that, a friction-stir spot welding tool is inserted from above the plate materials into the inside of the plate materials and foil materials while rotating (second step). Finally, the friction-stir spot welding tool is removed from the plate materials and foil materials (third step).

When the thickness of each of the multiple aluminum or aluminum alloy foil materials to be laminated is less than 0.3 mm, if a plate material is placed on the top layer of these foil materials, it is preferable that the thickness of the plate material be more than 0.5 mm. Also, if a foil material of the same composition is placed on the top layer of these foil materials, it is preferable that the thickness of the foil material to be placed be 0.3 mm or more and 0.5 mm or less.

The current-carrying component for a secondary battery of the present invention has a portion that is integrated by the friction stir spot joining method, so that even when the joining portion is joined to the electrode material by laser welding, the joining can be performed without affecting the electrode material. In addition, the thickness of the portion that is integrated by the friction stir spot joining method can be controlled by the joining conditions, so it can be used under various laser welding conditions.

1 is a plan view of a current-carrying component 100 for a secondary battery according to the present invention; A cross-sectional view of the current-carrying component 100 for a secondary battery shown in FIG. FIG. 2 is a plan view of a current-carrying component 200 for a secondary battery according to the present invention. BB line cross-sectional view of the current-carrying component 200 for a secondary battery shown in FIG. FIG. 3 is a plan view of a current-carrying component 300 for a secondary battery according to the present invention. 5 is a cross-sectional view of the current-carrying component 300 for a secondary battery taken along line CC in FIG. FIG. 4 is a plan view of a current-carrying component 400 for a secondary battery according to the present invention. 8 is a cross-sectional view of the current-carrying component 400 for a secondary battery shown in FIG. 7 along line D-D. FIG. 1 is a plan view of a current-carrying component 500 for a secondary battery according to the present invention. 9 is a cross-sectional view of the secondary battery current-carrying component 500 taken along line E-E. FIG. 1 is a schematic diagram showing a first step in a method for producing an electric current-carrying component for a secondary battery according to the present invention. FIG. 2 is a schematic diagram showing a second step in the method for producing an electric current-carrying component for a secondary battery according to the present invention. FIG. 1 is a schematic diagram showing a third step in the method for producing an electric-conducting component for a secondary battery according to the present invention. FIG. 2 is a schematic plan view of a test piece used in Examples 1 and 2. FIG. 2 is a schematic front view of the test piece (Example) used in Examples 1 and 2. FIG. 2 is a schematic front view of a test piece (comparative example) used in Examples 1 and 2.

The current-carrying components for secondary batteries according to the first to fifth embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a plan view of a current-carrying component for secondary batteries 100 according to the first embodiment of the present invention, FIG. 2 shows a cross-sectional view taken along the A-A line in the plan view, FIG. 3 shows a plan view of a current-carrying component for secondary batteries 200 according to the second embodiment, FIG. 4 shows a cross-sectional view taken along the B-B line in the plan view, FIG. 5 shows a plan view of a current-carrying component for secondary batteries 300 according to the third embodiment, FIG. 6 shows a cross-sectional view taken along the C-C line in the plan view, FIG. 7 shows a plan view of a current-carrying component for secondary batteries 400 according to the fourth embodiment, FIG. 8 shows a cross-sectional view taken along the D-D line in the plan view, FIG. 9 shows a plan view of a current-carrying component for secondary batteries 500 according to the fifth embodiment, and FIG. 10 shows a cross-sectional view taken along the E-E line in the plan view.

The current-carrying component for a secondary battery (first embodiment) 100 of the present invention is formed by stacking a plurality of metal (aluminum or aluminum alloy) foil materials 10, 20, 30, etc. in the thickness direction as shown in Figures 1 and 2. This current-carrying component for a secondary battery 100 has two joints 11, 12 as shown in Figures 1 and 2. Around these joints (recesses) 11, 12, integrated portions Y11, Y12 are formed by mixing and kneading adjacent metal foil materials in the vertical direction by a friction stir spot joining method as shown in Figure 2.

The current-carrying component for a secondary battery (second embodiment) 200 of the present invention is formed by stacking a plurality of metal foil materials 110, 120, 130, etc. in the thickness direction as shown in Figures 3 and 4, similar to the current-carrying component for a secondary battery 100 of the first embodiment. This current-carrying component for a secondary battery 200 has two joints 111, 112 as shown in Figures 3 and 4, similar to the current-carrying component for a secondary battery 100 of the first embodiment. Around these joints (recesses) 111, 112, integrated portions Y111, Y112 are formed by mixing and kneading the metal foil materials adjacent to each other in the vertical direction by a friction-stir spot joining method as shown in Figure 4.

In addition, one or more long holes (through holes) are provided in the center of the current-carrying component for secondary batteries (second embodiment) 200. These long holes 113, 114, 115 relieve bending stresses and the like that occur when the current-carrying component for secondary batteries (second embodiment) 200 is attached (installed) to other components such as electrode materials, and at the same time, release heat that is generated when the current-carrying component for secondary batteries (second embodiment) 200 is energized, i.e., are useful for heat dissipation.

The current-carrying component for a secondary battery (third embodiment) 300 of the present invention is formed by stacking a plurality of metal foil materials 210, 220, 230, etc. in the thickness direction as shown in Figures 5 and 6, similar to the current-carrying component for a secondary battery 100 of the first embodiment. This current-carrying component for a secondary battery 300 has two joints 211, 212 as shown in Figures 5 and 6, similar to the current-carrying component for a secondary battery 100 of the first embodiment. Around these joints (recesses) 211, 212, integrated portions Y211, Y212 are formed by mixing and kneading the metal foil materials adjacent to each other in the vertical direction by a friction-stir spot joining method as shown in Figure 6.

Furthermore, near the center of the current-carrying component for secondary batteries (third embodiment) 300, a bent portion C1 is formed that is curved in the thickness direction (upward in FIG. 6). This bent portion C1 is useful in that it relieves bending stresses that occur when the current-carrying component for secondary batteries (third embodiment) 300 is attached to other components such as electrode materials, prevents interference with other components when the current-carrying component for secondary batteries (third embodiment) 300 is attached to other components such as electrode materials, and allows the current-carrying component for secondary batteries (third embodiment) 300 to be efficiently arranged in a limited space. Note that while the bent portion C1 shown in FIG. 6 is composed only of curved portions, it may have a shape composed of multiple straight portions or a shape that combines curved portions and straight portions.

The current-carrying component for a secondary battery (fourth embodiment) 400 of the present invention is formed by stacking a plurality of metal foil materials 310, 320, 330, etc. in the thickness direction as shown in Figures 7 and 8, similar to the current-carrying component for a secondary battery 100 of the first embodiment. This current-carrying component for a secondary battery 400 has two joints 311, 312 as shown in Figures 7 and 8, similar to the current-carrying component for a secondary battery 100 of the first embodiment. Around these joints (recesses) 311, 312, integrated portions Y311, Y312 are formed by mixing and kneading the metal foil materials adjacent to each other in the vertical direction by a friction-stir spot joining method as shown in Figure 8.

Furthermore, the secondary battery current-carrying part (fourth embodiment) 400 has one or more long holes (through holes) in the center, similar to the secondary battery current-carrying part 200 of the second embodiment. These long holes 313, 314, 315 relieve bending stresses and the like that occur when the secondary battery current-carrying part (fourth embodiment) 400 is attached (installed) to other parts such as electrode materials, and at the same time, they are useful for releasing heat that is generated when the secondary battery current-carrying part (fourth embodiment) 400 is energized, i.e., for heat dissipation effects.

Furthermore, near the center of the current-carrying component for secondary batteries (fourth embodiment) 400, a bent portion C2 is formed that is bent in the thickness direction (upward in FIG. 8) in the same manner as the current-carrying component for secondary batteries 300 of the third embodiment. This bent portion C2 is useful in that it relieves bending stresses and the like that occur when the current-carrying component for secondary batteries (fourth embodiment) 300 is attached to other components such as electrode materials, prevents interference with other components when the current-carrying component for secondary batteries (third embodiment) 300 is attached to other components such as electrode materials, and allows the current-carrying component for secondary batteries (third embodiment) 300 to be efficiently arranged in a limited space. Note that while the bent portion C2 shown in FIG. 8 is composed only of curved portions, it may also be composed only of multiple straight portions or may have a shape that combines curved portions and straight portions.

The current-carrying component for a secondary battery (fifth embodiment) 500 of the present invention is formed by stacking a plurality of metal foil materials 410, 420, 430, etc. in the thickness direction as shown in Figures 9 and 10, similar to the current-carrying component for a secondary battery 100 of the first embodiment. This current-carrying component for a secondary battery 500 has two joints 411, 412 as shown in Figures 9 and 10, similar to the current-carrying component for a secondary battery 100 of the first embodiment. Around these joints (recesses) 411, 412, integrated portions Y411, Y412 are formed by mixing and kneading the metal foil materials adjacent to each other in the vertical direction by a friction-stir spot joining method as shown in Figure 10.

The joints 411, 412 are so-called through holes that pass from the front side to the back side of the current-carrying component for secondary batteries (fifth embodiment) 500, and are formed of small diameter parts 411a, 412a (diameter d1) and large diameter parts 411b, 412b (diameter d2) with different diameters. This is useful in that when the thickness of the current-carrying component for secondary batteries (fifth embodiment) 500 increases, the inside of the joints 411, 412 are stepped to reliably join and integrate the metal foil materials 410, 420, 430... and are also useful as positioning holes for the busbars. This stepped shape may also be applied to the current-carrying components for secondary batteries 200, 300, 400 of the second to fourth embodiments shown in Figures 3 to 8 described above.

Next, the manufacturing method of the current-carrying component for a secondary battery of the present invention, in particular the method of joining multiple sheets of metal foil material together by the friction stir spot joining method, will be described with reference to the drawings. Schematic diagrams of the first to third steps in the manufacturing method of the current-carrying component for a secondary battery of the present invention are shown in Figures 11 to 13, respectively. First, multiple sheets of metal foil material 510, 520, 530... are stacked (laminated) in the thickness direction as shown in Figure 11, and then a plate material B of the same material is further placed on the top layer (first step: Figure 11).

Then, while rotating the friction stir spot welding tool T from above the plate material B, the friction stir spot welding tool T is inserted from the plate material B side toward the metal foil materials 510, 520, 530... side to join the metal foil materials 510, 520, 530... to each other (second step: Figure 12). The plate material B is pushed out of the outer periphery of the tool and joined to the adjacent metal foil material 510.

Finally, the friction stir spot welding tool T is removed from the metal foil materials 510, 520, 530, and plate material B (third step: FIG. 13). The area where the friction stir spot welding tool T was removed is formed as the joint (joint) 511 of the secondary battery current-carrying component 600. At the same time, an integrated portion Y511 is formed around the joint (recess) 511, in which adjacent metal foil materials in the vertical direction are mixed and kneaded by the friction stir spot welding method, as shown in FIG. 13.

Note that in this embodiment of the manufacturing method for a current-carrying component for a secondary battery shown in Figures 11 to 13, if the thickness of each of the multiple aluminum or aluminum alloy foil materials to be stacked is less than 0.3 mm, the thickness of "plate material B" shown in Figure 11 can be more than 0.5 mm. Also, instead of "plate material B", a foil material of the same composition as the multiple foil materials to be stacked may be further placed in the uppermost layer. In this case, it is preferable that the thickness of the foil material placed in the uppermost layer is 0.3 mm or more.

In addition, in this embodiment, integrated parts Y11 and Y12 in FIG. 2, integrated parts Y111 and Y112 in FIG. 4, integrated parts Y211 and Y212 in FIG. 6, integrated parts Y311 and Y312 in FIG. 8, integrated parts Y411 and Y412 in FIG. 10, and integrated part Y511 in FIG. 13 show cross-sectional shapes in which all of the metal foil materials stacked in the thickness direction are integrated, but the joining shape of the metal foil materials joined by friction stir spot joining is not limited to the shapes shown in these figures.

In other words, the joints in the current-carrying component for a secondary battery of the present invention may be in a form in which, for example, multiple sheets of metal foil material near the surface layer are integrated (physically integrated) with each other, and the remaining sheets of metal foil material near the lower layer are in close contact (pressed) with each other.

Example 1
A test (hereinafter, referred to as a current test) was conducted to confirm the current performance when the current-carrying part of the present invention (Example) and the conventional current-carrying part (Comparative Example) were assembled into a secondary battery, and the test results will be described with reference to the drawings. The test piece used in the current-carrying test of this embodiment was made by using two aluminum alloy (A1050) plate materials (width 20 mm x length 40 mm x thickness 1.2 mm) at both ends, and installing a foil or plate material made of the same aluminum alloy (A1050) in a form that bridges the ends of these two plate materials, and then joining the overlapping parts of the two plate materials by friction stir welding to produce a test piece. A plan view of the test piece used in the current-carrying test (common to the Example and Comparative Example) is shown in FIG. 14, a front view of the Example in FIG. 15, and a front view of the Comparative Example in FIG. 16, respectively.

In the example used in the current test, seven sheets of aluminum alloy foil (width 20 mm x length 64 mm x thickness 0.3 mm) were stacked as the bridging material described above, and the test piece was integrated by friction stir welding at the overlapping part of the two sheets (the joint was where the sheet and foil were joined). On the other hand, in the comparative example, one aluminum alloy plate (width 20 mm x length 64 mm x thickness 2.0 mm) was placed as the bridging material described above, and the test piece was joined by friction stir welding at the overlapping part of the two sheets (the joint was where the two sheets were joined). In both the example and the comparative example, holes (holes for connecting the current device) were machined in the two sheets at both ends as shown in Figure 14 for connecting to the current device.

After connecting the cables of the current-carrying device to the holes provided at both ends of each test piece of the Examples and Comparative Examples, current was continuously applied to the test pieces for a predetermined time under the following two conditions, and the change in voltage (current-carrying voltage) measured during that time was measured. Table 1 shows the current-carrying voltage values (maximum voltage values) of the Examples and Comparative Examples in the current-carrying test and the electrical resistance values calculated from the current-carrying voltage values.
Current condition 1: current value 400A x current application time 1000 seconds Current condition 2: current value 900A x current application time 30 seconds

As shown in Table 1, the results of the current test were that when the current flow rate was 400 A and the current flow time was 1000 seconds, the voltage value was 0.26 V (electrical resistance value was 0.65 mΩ) for both the Example and Comparative Example. When the current flow rate was 900 A and the current flow time was 30 seconds, the voltage value for the Example was 0.56 V (electrical resistance value was 0.62 mΩ) and the voltage value for the Comparative Example was 0.57 V (electrical resistance value was 0.63 mΩ). No difference in voltage value (electrical resistance value) was observed between the Example and Comparative Example under any of the current flow conditions.

Example 2
Next, a test was conducted to confirm the lateral load resistance when the two types of current-carrying parts used in Example 1 were assembled into a secondary battery, and the test results will be described. In this test, both the Example and the Comparative Example used test pieces of the same dimensions as those used in Example 1, and both ends of the test pieces were fixed to two gripping tools in the vertical direction attached to the Amsler tester, and then the load value at a predetermined stroke (the distance between the gripping tools in the vertical direction) was measured in a compression test mode in which the two gripping tools were moved closer to each other. The results of the load values and the like of the Example and the Comparative Example measured when the stroke distance of the tester was 0.8 mm, 0.9 mm, and 1.0 mm are shown in Table 2. The movement speed of the gripping tools of the Amsler tester was set to 1 mm/sec.

As a result of this test, as shown in Table 2, the load values for the Example at strokes of 0.8 mm and 0.9 mm were 80 N and 198 N, respectively, which were 30 to 40 N lower than the measured values for the Comparative Example at the same stroke. Furthermore, at a stroke of 1.0 mm, the aluminum alloy foil material in the center of the test piece was deformed (bent), and no deformation was observed at the joint or the gripped parts at both ends.

In contrast, the load values for the comparative example at strokes of 0.8 mm and 0.9 mm were 111 N and 240 N, respectively, which were 30 to 40 N higher than the measured values for the example at the same stroke. At a stroke of 1.0 mm, the gripping portions at both ends were deformed, and fracture of the joints was confirmed.

From the above test results, the Example (current-carrying component in which aluminum alloy foil materials are laminated and bonded) has a smaller load value against a lateral load than the Comparative Example (current-carrying component in which aluminum alloy plate materials are bonded together). Therefore, when bonding the Example (current-carrying component) to the electrode material, it has the advantage of being able to flexibly accommodate variations in the height and length of the electrode material, and to easily follow the movement of the electrode material even in a state in which the Example is bonded to the electrode material.

10, 20, 30 Metal foil material 11, 12 Joint portion 100 Current-carrying part for secondary battery 411a Small diameter portion of recess 411b Large diameter portion of recess d1 Diameter of small diameter portion d2 Diameter of large diameter portion B Plate material C1, C2 Bent portion T Friction stir spot joining tool Y11, Y12 Stirred and kneaded integrated portion

Claims (7)

1. A current-carrying component for a secondary battery formed from multiple sheets of aluminum or aluminum alloy foil material, the multiple sheets of foil material being stacked in the thickness direction, and the foil materials adjacent in the thickness direction have joints joined by friction stir spot welding.
2. The current-carrying component for a secondary battery according to claim 1, characterized in that there are five or more sheets of foil material, and each sheet of foil material has a thickness of 0.5 mm or less.
3. The current-carrying component for a secondary battery according to claim 1 or 2, characterized in that the foil material further has a bent portion bent in a straight or curved shape.
4. The method for manufacturing a current-carrying part for a secondary battery according to claim 1, characterized in that it comprises a first step of stacking the plurality of aluminum or aluminum alloy foil materials and then placing a plate material of the same composition as the foil material on the top layer, a second step of inserting a friction-stir spot welding tool into the inside of the plate material and the foil material from above the plate material while rotating the tool after the first step, and a third step of removing the friction-stir spot welding tool from the inside of the plate material and the foil material after the second step.
5. The method for manufacturing a current-carrying part for a secondary battery according to claim 1, characterized in that it comprises a first step of stacking the plurality of aluminum or aluminum alloy foil materials and then placing a foil material of the same composition as the plurality of foil materials in the uppermost layer, a second step of inserting a friction stir spot welding tool into the interior of the plurality of foil materials from above the foil material placed in the uppermost layer after the first step while rotating the tool, and a third step of removing the friction stir spot welding tool from the foil material placed in the uppermost layer and from the interior of the plurality of foil materials after the second step.
6. The method for manufacturing a current-carrying component for a secondary battery according to claim 4, characterized in that the thickness of each of the foil materials is less than 0.3 mm, and the thickness of the plate material is more than 0.5 mm.
7. The method for manufacturing an electrical conductive component for a secondary battery according to claim 5, characterized in that the thickness of each of the plurality of foil materials is less than 0.3 mm, and the thickness of the foil material placed on the top layer is 0.3 mm or more and 0.5 mm or less.
   
   
   
   

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