Conductive component for secondary battery, and manufacturing method thereof

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 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 or foils, particularly current-carrying components for secondary batteries in automobiles and the like, are also called bus bars, and a technology has been disclosed for forming them from highly conductive materials such as aluminum alloys and copper alloys (see Patent Document 1).

[0003] Japanese Patent No. 6971990

[0004] However, when multiple layers of metal foil material are laminated and then joined to an electrode material below using laser welding or the like, the heat and vibrations from the laser welding or the like do not easily reach the metal foil material below, which makes it difficult to join the electrode material to the current-carrying component formed from multiple layers of metal foil material. Even if joining could be achieved using high-power laser welding or the like, there is still the problem of deformation and other effects occurring in the electrode material below.

[0005] Therefore, an object of the present invention is to provide an electrically conductive 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.

[0006] The current-carrying component for a secondary battery of the present invention is formed from multiple aluminum or aluminum alloy foil sheets. These multiple foil sheets are stacked in the thickness direction, and adjacent foil sheets in the thickness direction are joined by friction stir spot welding. The number of foil sheets may be five or more, and each foil sheet may have a thickness of 0.5 mm or less. Furthermore, the foil sheets may further have a bent portion in which the foil sheet is bent in a linear or curved shape.

[0007] In the method for manufacturing a secondary battery current-carrying component of the present invention, first, multiple aluminum or aluminum alloy foils are stacked, and then a plate material of the same composition as the foils is placed on top (Step 1). Then, a friction-stir spot welding tool is inserted into the plate and foil materials while rotating from above (Step 2). Finally, the friction-stir spot welding tool is removed from the plate and foil materials (Step 3).

[0008] When the thickness of each of the aluminum or aluminum alloy foils to be laminated is less than 0.3 mm, and a plate material is placed on top of these foils, the thickness of the plate material is preferably more than 0.5 mm. Furthermore, when a foil material of the same composition is placed on top of these foils, the thickness of the foil material to be placed is preferably 0.3 mm to 0.5 mm.

[0009] The current-carrying component for a secondary battery of the present invention has a portion integrated by friction stir spot welding, and therefore can be joined to an electrode material by laser welding without affecting the electrode material. In addition, the thickness of the portion integrated by friction stir spot welding can be controlled by the joining conditions, so it can be used under various laser welding conditions.

[0010] 7 is a plan view of a current-carrying component 100 for a secondary battery of the present invention; FIG. 1 is a cross-sectional view along line A-A of the current-carrying component 100 for a secondary battery shown in FIG. 1; FIG. 2 is a cross-sectional view along line B-B of the current-carrying component 200 for a secondary battery shown in FIG. 3; FIG. 3 is a cross-sectional view along line C-C of the current-carrying component 300 for a secondary battery shown in FIG. 5; FIG. 4 is a cross-sectional view along line D-D of the current-carrying component 400 for a secondary battery shown in FIG. 7; FIG. 4 is a cross-sectional view along line E-E of the current-carrying component 500 for a secondary battery shown in FIG. 9; FIG. 5 is a cross-sectional view along line E-E of the current-carrying component 500 for a secondary battery shown in FIG. 9; FIG. 6 is a schematic view showing a first step in the manufacturing method of a current-carrying component for a secondary battery of the present invention; FIG. 7 is a schematic view showing a second step in the manufacturing method of a current-carrying component for a secondary battery of the present invention; FIG. 8 is a schematic view showing a third step in the manufacturing method of a current-carrying component for a secondary battery of the present invention; FIG. 9 is a schematic plan view of a test piece used in Examples 1 and 2. FIG. 10 is a schematic front view of the test piece (Example) used in Examples 1 and 2. FIG. 1 is a schematic front view of a test piece (comparative example) used in Examples 1 and 2.

[0011] The following describes current-carrying components for secondary batteries according to first to fifth embodiments of the present invention. Fig. 1 shows a plan view of a current-carrying component for secondary batteries 100 according to a first embodiment of the present invention, Fig. 2 shows a cross-sectional view taken along line A-A in the plan view, Fig. 3 shows a plan view of a current-carrying component for secondary batteries 200 according to a second embodiment of the present invention, Fig. 4 shows a cross-sectional view taken along line B-B in the plan view, Fig. 5 shows a plan view of a current-carrying component for secondary batteries 300 according to a third embodiment of the present invention, Fig. 6 shows a cross-sectional view taken along line C-C in the plan view, Fig. 7 shows a plan view of a current-carrying component for secondary batteries 400 according to a fourth embodiment of the present invention, Fig. 8 shows a cross-sectional view taken along line D-D in the plan view, and Fig. 9 shows a plan view of a current-carrying component for secondary batteries 500 according to a fifth embodiment of the present invention, and Fig. 10 shows a cross-sectional view taken along line E-E in the plan view.

[0012] 1 and 2, a secondary battery current-carrying component (first embodiment) 100 of the present invention is formed by stacking a plurality of metal (aluminum or aluminum alloy) foil materials 10, 20, 30, ... in the thickness direction. This secondary battery current-carrying component 100 has two joining portions 11, 12 as shown in Fig. 1 and 2. Around these joining portions (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 Fig. 2.

[0013] Similar to the current-carrying component 100 for a secondary battery of the first embodiment, a current-carrying component for a secondary battery (second embodiment) 200 for a secondary battery of the present invention is formed by stacking a plurality of metal foil materials 110, 120, 130... in the thickness direction as shown in Figures 3 and 4. Similar to the current-carrying component 100 for a secondary battery 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. Around these joints (recesses) 111, 112, integrated portions Y111, Y112 are formed by mixing and kneading adjacent metal foil materials together in the vertical direction by a friction stir spot joining method as shown in Figure 4.

[0014] Furthermore, one or more elongated holes (through holes) are provided in the center of the current-carrying component for secondary batteries (second embodiment) 200. These elongated holes 113, 114, 115 relieve bending stress and the like that occurs when the current-carrying component for secondary batteries (second embodiment) 200 is attached (placed) to other components such as electrode materials, and at the same time, release heat that is generated when current is applied to the current-carrying component for secondary batteries (second embodiment) 200, i.e., are useful for heat dissipation.

[0015] Similar to the current-carrying component 100 for a secondary battery of the first embodiment, a current-carrying component 300 for a secondary battery (third embodiment) of the present invention is formed by stacking a plurality of metal foil materials 210, 220, 230... in the thickness direction as shown in Figures 5 and 6. Similar to the current-carrying component 100 for a secondary battery of the first embodiment, this current-carrying component 300 for a secondary battery has two joints 211, 212 as shown in Figures 5 and 6. Around these joints (recesses) 211, 212, integrated portions Y211, Y212 are formed by mixing and kneading adjacent metal foil materials together in the vertical direction by a friction stir spot joining method as shown in Figure 6.

[0016] Furthermore, a bent portion C1 curved in the thickness direction (upward in FIG. 6 ) is formed near the center of the secondary battery current-carrying component (third embodiment) 300. This bent portion C1 is useful in that it relieves bending stress and the like that occurs when the secondary battery current-carrying component (third embodiment) 300 is attached to another component such as an electrode material, prevents interference with other components when the secondary battery current-carrying component (third embodiment) 300 is attached to another component such as an electrode material, and allows the secondary battery current-carrying component (third embodiment) 300 to be efficiently arranged in a limited space. Note that, although 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.

[0017] Similar to the secondary battery current-carrying component 100 of the first embodiment, a secondary battery current-carrying component 400 (fourth embodiment) of the present invention is formed by stacking a plurality of metal foil materials 310, 320, 330... in the thickness direction as shown in Figures 7 and 8. Similar to the secondary battery current-carrying component 100 of the first embodiment, this secondary battery current-carrying component 400 has two joints 311, 312 as shown in Figures 7 and 8. Around these joints (recesses) 311, 312, integrated portions Y311, Y312 are formed by mixing and kneading vertically adjacent metal foil materials together using a friction stir spot joining method as shown in Figure 8.

[0018] Furthermore, one or more elongated holes (through holes) are provided in the center of the current-carrying component for a secondary battery (fourth embodiment) 400, similar to the current-carrying component for a secondary battery 200 of the second embodiment. These elongated holes 313, 314, 315 relieve bending stress and the like that occurs when the current-carrying component for a secondary battery (fourth embodiment) 400 is attached (placed) to other components such as electrode materials, and at the same time, they are useful for releasing heat that is generated when current is applied to the current-carrying component for a secondary battery (fourth embodiment) 400, i.e., for heat dissipation.

[0019] Furthermore, a bent portion C2 curved in the thickness direction (upward in FIG. 8 ) is formed near the center of the secondary battery current-carrying component (fourth embodiment) 400, similar to the case of the secondary battery current-carrying component 300 of the third embodiment. This bent portion C2 is useful in that it relieves bending stress and the like that occurs when the secondary battery current-carrying component 300 is attached to another component such as an electrode material, prevents interference with other components when the secondary battery current-carrying component 300 is attached to another component such as an electrode material, and allows the secondary battery current-carrying component (third embodiment) 300 to be efficiently arranged in a limited space. Note that, although the bent portion C2 shown in FIG. 8 is composed only of curved portions, it may also have a shape composed only of a plurality of straight portions or a shape that combines curved portions and straight portions.

[0020] Similar to the current-carrying component 100 for a secondary battery of the first embodiment, a current-carrying component 500 for a secondary battery (fifth embodiment) of the present invention is formed by stacking a plurality of metal foil materials 410, 420, 430... in the thickness direction as shown in Figures 9 and 10. Similar to the current-carrying component 100 for a secondary battery of the first embodiment, this current-carrying component 500 for a secondary battery has two joints 411, 412 as shown in Figures 9 and 10. Around these joints (recesses) 411, 412, integrated portions Y411, Y412 are formed by mixing and kneading vertically adjacent metal foil materials together using a friction stir spot joining method as shown in Figure 10.

[0021] Furthermore, each of the joints 411, 412 is a so-called through-hole extending from the front side to the back side of the current-carrying component for a secondary battery (fifth embodiment) 500, and is formed of a small-diameter portion 411a, 412a (diameter d1) and a large-diameter portion 411b, 412b (diameter d2), each with a different diameter. This is useful for reliably joining and integrating the metal foil materials 410, 420, 430... when the thickness of the current-carrying component for a secondary battery (fifth embodiment) 500 increases, by forming the inside of the joints 411, 412 in a stepped shape. This is also useful as a positioning hole for the bus bar. This stepped shape may also be applied to the current-carrying components for a secondary battery 200, 300, 400 of the second to fourth embodiments shown in Figures 3 to 8.

[0022] Next, a method for manufacturing a current-carrying component for a secondary battery according to the present invention, particularly a method for joining multiple sheets of metal foil material by friction stir spot joining, will be described with reference to the drawings. Schematic diagrams of steps 1 to 3 of the method for manufacturing a current-carrying component for a secondary battery according to the present invention are shown in Figures 11 to 13, respectively. First, multiple sheets of metal foil material 510, 520, 530... are stacked (layered) in the thickness direction as shown in Figure 11, and then a plate material B made of the same material is placed on top of the top layer (step 1: Figure 11).

[0023] Thereafter, 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..., thereby joining the metal foil materials 510, 520, 530... to one another (second step: FIG. 12). The plate material B is pushed out of the outer periphery of the tool and joined to the adjacent metal foil material 510.

[0024] Finally, the friction stir spot welding tool T is removed from the metal foil materials 510, 520, 530, and the plate material B (third step: FIG. 13). The area from which the friction stir spot welding tool T was removed is formed as the joining portion (joining location) 511 of the secondary battery current-carrying component 600. At the same time, an integrated portion Y511 is formed around the joining portion (recess) 511 by mixing and kneading the metal foil materials adjacent to each other in the vertical direction using the friction stir spot welding method, as shown in FIG.

[0025] In the present embodiment of the manufacturing method for a secondary battery current-carrying component shown in Figures 11 to 13, if the thickness of each of the multiple aluminum or aluminum alloy foil sheets to be stacked is less than 0.3 mm, the thickness of "sheet material B" shown in Figure 11 can be greater than 0.5 mm. Furthermore, instead of "sheet material B," a foil material having the same composition as the multiple foil sheets to be stacked may be placed as the top layer. In this case, the thickness of the foil material placed as the top layer is preferably 0.3 mm or more.

[0026] In addition, in this embodiment, integrated portions Y11 and Y12 in Figure 2, integrated portions Y111 and Y112 in Figure 4, integrated portions Y211 and Y212 in Figure 6, integrated portions Y311 and Y312 in Figure 8, integrated portions Y411 and Y412 in Figure 10, and integrated portion Y511 in Figure 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.

[0027] In other words, the joint 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 metal foil material near the lower layer is in close contact (pressed) with each other.

[0028] Example 1 A test (hereinafter referred to as a "current test") was conducted to confirm the current-carrying performance of a current-carrying component of the present invention (Example) and a conventional current-carrying component (Comparative Example) when assembled into a secondary battery. The test results are described with reference to the drawings. The test specimen used in the current-carrying test of this Example was prepared by using two aluminum alloy (A1050) plates (20 mm wide x 40 mm long x 1.2 mm thick) at both ends, with a foil or plate made of the same aluminum alloy (A1050) placed on each end to bridge the ends of the two plates, and then joining the overlapping portions of the two plates by friction stir welding. A plan view of the test specimen (common to the Example and Comparative Example) used in the current-carrying test 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.

[0029] In the example used in the current test, seven sheets of aluminum alloy foil (20 mm wide x 64 mm long x 0.3 mm thick) were stacked as the bridging material, and the test piece was integrated by friction stir welding at the overlapping portion of the two sheets (the joint was the portion where the sheet and foil were joined). On the other hand, in the comparative example, a single aluminum alloy plate (20 mm wide x 64 mm long x 2.0 mm thick) was placed as the bridging material, and the test piece was joined by friction stir welding at the overlapping portion of the two sheets (the joint was the portion where the two sheets were joined). In both the example and the comparative example, holes for connecting to the current-carrying device (current-carrying device connection holes) were drilled in the two plates at both ends, as shown in FIG.

[0030] After connecting the cables of a current-carrying device to the holes provided at both ends of each test piece of these Examples and Comparative Examples, current was continuously applied to the test piece for a predetermined time under the following two conditions, and the change in voltage (energized voltage) measured within that time was measured. The energized voltage values ​​(maximum voltage values) of the Examples and Comparative Examples in the energization test and the electrical resistance values ​​calculated from the energized voltage values ​​are shown in Table 1. Current-carrying condition 1: current value 400 A x current-carrying time 1000 seconds Current-carrying condition 2: current value 900 A x current-carrying time 30 seconds

[0031]

[0032] As shown in Table 1, the results of the current test showed 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 the 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 the Comparative Example under any of the current flow conditions.

[0033] Example 2 Next, a test was conducted to confirm the lateral load resistance when the two types of current-carrying components used in Example 1 were assembled into a secondary battery. The test results are described below. In this test, both the Example and Comparative Example used test specimens of the same dimensions as those used in Example 1. Both ends of the test specimen were fixed to two vertical clamps attached to an Amsler testing machine, and the load value was measured at a predetermined stroke (the distance between the vertical clamps) using a compression test mode in which the two clamps were moved toward each other. Table 2 shows the load values ​​and other results for the Example and Comparative Example measured when the stroke distance of the test machine was 0.8 mm, 0.9 mm, and 1.0 mm. The Amsler testing machine's clamp movement speed was 1 mm / sec.

[0034]

[0035] As a result of this test, the load values ​​for the Example at strokes of 0.8 mm and 0.9 mm were 80 N and 198 N, respectively, as shown in Table 2, 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), but no deformation was observed at the joint or the gripped portions at both ends.

[0036] 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 values ​​measured 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 joint was confirmed.

[0037] From the above test results, the Example (current-carrying component formed by laminating and joining aluminum alloy foil materials) has a smaller load value against a lateral load than the Comparative Example (current-carrying component formed by joining aluminum alloy plate materials together). Therefore, when joining 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 easily follow the movement of the electrode material even when joined to the electrode material.

[0038] 10, 20, 30 Metal foil material 11, 12 Joint portion 100 Current-carrying component 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 Stir-mixed integrated portion

Claims

1. A current-carrying component for a secondary battery formed from a plurality of foil materials made of aluminum or aluminum alloy, wherein the plurality of foil materials are laminated in the thickness direction, and the foil materials adjacent to each other in the thickness direction have a plurality of joints joined by friction stirring spot welding, Among the plurality of joints, two of the joints in a direction orthogonal to the thickness direction are provided at a set distance apart. A current-carrying component for a secondary battery characterized by this.

2. The current-carrying component for a secondary battery according to claim 1, wherein the number of the foil materials is 5 or more, and the thickness of each of the foil materials is 0.5 mm or less.

3. The current-carrying component for a secondary battery according to claim 1 or 2, further provided with a bent portion where the foil material is bent linearly or curvilinearly.

4. A method for manufacturing a current-carrying component for a secondary battery according to claim 1, comprising: a first step of laminating the plurality of foil materials made of aluminum or aluminum alloy and installing a plate material having the same composition as the foil material on the uppermost layer; a second step of inserting a friction stirring spot welding tool into the plate material and the foil materials while rotating the tool from above the plate material after the first step; and a third step of extracting the friction stirring spot welding tool from inside the plate material and the foil materials after the second step. A method for manufacturing a current-carrying component for a secondary battery characterized by this.

5. A method for manufacturing a current-carrying component for a secondary battery according to claim 1, comprising: a first step of laminating the plurality of foil materials made of aluminum or aluminum alloy and installing a foil material having the same composition as the plurality of foil materials on the uppermost layer; a second step of inserting a friction stirring spot welding tool into the plurality of foil materials while rotating the tool from above the foil material installed on the uppermost layer after the first step; and a third step of extracting the friction stirring spot welding tool from inside the foil material installed on the uppermost layer and the plurality of foil materials after the second step. A method for manufacturing a current-carrying component for a secondary battery characterized by this.

6. The method for manufacturing a current-carrying component for a secondary battery according to claim 4, wherein 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 a current-carrying component for a secondary battery according to claim 5, wherein the thickness of each of the plurality of foil materials is less than 0.3 mm, and the thickness of the foil material installed on the uppermost layer is 0.3 mm or more and 0.5 mm or less.