Conductive connecting components and conductive connecting structures

Abstract

To provide a conductive connection component that can form an appropriate fusion weld by more general laser welding that does not use a welding wire between a positive electrode side joint and a busbar side joint of dissimilar materials, and a conductive connection structure having suitable connection strength.SOLUTION: A conductive connection structure has a first bonding region that is composed of a cladding material of an Fe layer and an Al layer and can be laser welded to a Fe-based bonding portion on the positive electrode side of a battery, a second bonding region that can be bonded to an Al-based bonding portion of a bus bar, and a laser receiving region. The first bonding region is provided on the surface of the Fe layer, the second bonding region is provided on the surface of the Al layer, the laser receiving region is provided on the surface opposite to the first bonding region in the thickness direction. When the thickness of the Fe layer in the part where the bonding region is provided is Ts, and the thickness of the Al layer in the part where the laser receiving region is provided is Ta, the conductive connection component satisfies 0≤Ta≤Ts / 10. Using this, a conductive connection structure with a tensile breaking load of 600N or more is obtained.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to conductive connecting components and conductive connecting structures used for electrical connections in batteries and the like. [Background technology]

[0002] Conventionally, battery systems use busbars made of conductive metal to electrically connect multiple battery cells. The busbars are connected to the positive or negative electrode joints of the battery cells, which are made of conductive metal, by joining methods such as laser welding using welding wire or laser welding without welding wire. In the case of the more common laser welding without welding wire, for example, the busbar joint is brought into contact with the positive electrode joint (or negative electrode joint), and laser light is shone onto the outer surface of the busbar from the opposite side (the outer surface side of the busbar). This partially melts and solidifies both the area from the outer surface of the busbar to the busbar joint, and the area from the surface of the positive electrode joint (or negative electrode joint) in contact with the busbar joint to a desired depth on the positive electrode joint (or negative electrode joint), forming a fused joint and creating a conductive connection structure.

[0003] Incidentally, the conductive metal constituting the positive electrode joint (or negative electrode joint) and the conductive metal constituting the busbar joint may be made of different materials. In this case, because the joints are made of dissimilar conductive metals, there is a risk that an excessive amount of fragile intermetallic compounds may be present in the fusion weld formed at the contact point, resulting in a conductive connection structure with insufficient connection strength. In laser welding of such dissimilar materials, a known method involves interposing a conductive connection component made of cladding material between the two joints made of dissimilar conductive metals to be joined.

[0004] For example, in joining dissimilar materials, such as an Al joint made of Al or an Al alloy and an Fe joint made of Fe or an Fe alloy, a clad insert (conductive connecting component) with a two-layer structure consisting of an Al layer of the same quality as the Al joint and an Fe layer of the same quality as the Fe joint is interposed. This clad insert allows the dissimilar material joint structure to be replaced with a joint structure of the same material. Although not laser welding, one example is the clad insert disclosed in Patent Document 1. The clad insert disclosed in Patent Document 1 has a specific plate thickness configuration consisting of a steel layer and an Al layer, and is used in resistance welding between a steel plate (Fe joint) and an Al plate (Al joint). The plate thickness configuration of this clad insert is such that the thickness of the steel layer is T S (mm), the thickness of the Al layer is T A (mm), the resistivity of the steel layer is R S When T is (μΩ·cm), S >(30 / R S )×T A This satisfies -0.3. As a result, the range of appropriate welding conditions for resistance welding is broadened, enabling the formation of appropriate and stable nuggets (fused joints), and thus a conductive connection structure with high connection strength (joint strength) can be obtained. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-155964 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The clad insert disclosed in Patent Document 1 is used for resistance welding of steel plates (Fe joint) and aluminum plates (Al joint), rather than laser welding. Resistance welding is a welding method in which at least two metal materials to be welded are overlapped, the welding area is sandwiched between electrodes, an appropriate current is passed while applying appropriate pressure, and the metal materials to be welded are melted and solidified by Joule heating caused by the contact resistance at the welding area. However, in recent years, miniaturization and space saving of the above-mentioned battery systems have become increasingly important, and conductive connection structures in which the positive electrode side joint (Fe joint) and the busbar side joint (Al joint) cannot be sandwiched between electrodes are increasing. Therefore, improving the reliability of the connection (joint) between the positive electrode side joint and the busbar side joint by laser welding is urgently needed. Furthermore, there is a strong demand to enable shorter welding times and improved productivity using laser welding that does not use more common welding wires. However, even if a clad insert plate thickness configuration specifically for resistance welding, as disclosed in Patent Document 1, is adopted for general laser welding, there is a risk that a conductive connection structure with desirable connection strength (joint strength) may not be obtained.

[0007] The object of this invention is to provide a conductive connecting component (clad insert) having an Fe layer and an Al layer that enables the formation of a suitable fusion joint in a more general laser welding process that does not use welding wire between a positive electrode side joint and a busbar side joint made of different materials, and to provide a conductive connecting structure having a desirable connection strength using this conductive connecting component. [Means for solving the problem]

[0008] The inventors of this invention discovered that the above problem can be solved by specifying the arrangement of a first bonding region for the positive electrode side bonding portion, a second bonding region for the busbar side bonding portion, and a laser light receiving region in a clad insert formed by rolling and bonding an Fe layer and an Al layer, and by specifying the relationship between the thickness of the Fe layer in the area where the first bonding region is located and the thickness of the Al layer in the area where the laser light receiving region is located, and thus came up with this invention.

[0009] In other words, the conductive connecting component according to this invention is made of a clad material formed by rolling and joining an Fe layer made of Fe or an Fe alloy and an Al layer made of Al or an Al alloy, and has a first joining region that can be laser welded to a positive electrode side joining portion made of Fe or an Fe alloy provided on the positive electrode side of a battery, a second joining region that can be joined to a busbar side joining portion made of Al or an Al alloy provided on the busbar side, and a laser receiving region that can receive laser light, wherein the first joining region is provided on the surface of the Fe layer along the rolling direction, the second joining region is provided on the surface of the Al layer along the rolling direction, and the laser receiving region is provided on the surface of the clad material opposite to the first joining region in the thickness direction, and when the thickness of the Fe layer in the portion where the first joining region is provided is Ts and the thickness of the Al layer in the portion where the laser receiving region is provided is Ta, the value of 0 ≤ Ta ≤ Ts / 10 is satisfied. With this conductive connecting component, a conductive connecting structure having a desirable connection strength (joint strength) can be obtained.

[0010] By using the conductive connecting component according to this invention, a conductive connecting structure having desirable connection strength (joint strength) can be obtained. In other words, the conductive connection structure according to this invention is a conductive connection structure configured by connecting a positive electrode side joint made of Fe or an Fe alloy provided on the positive electrode side of a battery and a busbar side joint made of Al or an Al alloy provided on the busbar side via a conductive connection component made of a clad material formed by rolling and joining an Fe layer made of Fe or an Fe alloy and an Al layer made of Al or an Al alloy, wherein the conductive connection structure has a first joint connecting the conductive connection component and the positive electrode side joint, a second joint connecting the conductive connection component and the busbar side joint, and a fusion mark on the surface of the conductive connection component opposite to the first joint in the thickness direction, and when the thickness of the Fe layer in the portion with the first joint is Ts and the thickness of the Al layer in the portion with the fusion mark is Ta, the condition 0 ≤ Ta ≤ Ts / 10 is satisfied, and the tensile breaking load between the positive electrode side and the conductive connection component in the thickness direction of the conductive connection component is 600 N or more (preferably 650 N or more).

[0011] Further, in the conductive connection structure according to the present invention, preferably, the tensile breaking stress between the positive electrode side and the conductive connection component in the thickness direction of the conductive connection component is 250 MPa or more (preferably 280 MPa or more, more preferably 300 MPa or more).

[0012] Also, in the conductive connection structure according to the present invention, preferably, when the penetration depth of the first joint with respect to the positive electrode side joint is Dp, Dp ≧ 0.18 mm (preferably Dp ≧ 0.20 mm) is satisfied, and when the penetration cross-sectional area of the first joint with respect to the positive electrode side joint is St, St ≧ 1.2 mm 2 (preferably St ≧ 1.3 mm 2 ) is satisfied. [Effect of the Invention]

[0013] According to the present invention, in a more general laser welding that does not use a welding wire for welding the positive electrode side joint and the bus bar side joint of different materials, it is possible to provide a conductive connection component (clad insert) having an Fe layer and an Al layer that enables the formation of an appropriate welded portion, and to provide a conductive connection structure having a preferable connection strength (joint strength) using the conductive connection component. [Brief Description of the Drawings]

[0014] [Figure 1] It is a diagram showing a configuration that is an embodiment of the conductive connection structure according to the present invention. [Figure 2] It is a diagram showing a configuration that is an embodiment of the conductive connection component according to the present invention, and showing the configuration of the conductive connection component before being incorporated into the conductive connection structure shown in FIG. 1. [Figure 3] It is a diagram showing a cross-sectional view along the thickness direction in the vicinity of the first joint 4 shown in FIG. 1. [Figure 4] It is a diagram showing a configuration that is an embodiment of the conductive connection component according to the present invention. [Figure 5] It is a diagram showing a configuration that is an embodiment of the conductive connection component according to the present invention. [Figure 6] It is a diagram showing a configuration that is an embodiment of the conductive connection component according to the present invention. [Figure 7] This figure shows a configuration that represents one embodiment of a conductive connecting component according to this invention. [Figure 8] This figure shows a configuration that represents one embodiment of a conductive connecting component according to this invention. [Figure 9] This figure shows a joint structure that mimics an embodiment of the conductive connection structure according to this invention. [Modes for carrying out the invention]

[0015] The conductive connecting component and conductive connecting structure according to this invention will be described below with reference to the drawings as appropriate. However, the embodiments of the conductive connecting component and conductive connecting structure according to this invention are not limited to the configuration examples described with reference to the drawings. It is reasonable to understand that the embodiments of the conductive connecting component and conductive connecting structure according to this invention include all modifications shown in the claims and within the meaning and scope equivalent to the claims.

[0016] First, let's describe one embodiment of the conductive connection structure according to this invention. The conductive connection structure 1 shown in Figure 1 is one embodiment of the conductive connection structure according to this invention. The conductive connection structure shown in Figure 1 is configured on the positive electrode side of a battery (battery cell 2). This conductive connection structure 1 consists of the positive electrode terminal 2b of the battery cell 2, a busbar 3, and a conductive connection component 10 (clad insert). This battery cell 2 may be, for example, one of a plurality of battery cells in a battery system.

[0017] In a typical battery (battery cell), a positive terminal is provided on the positive electrode side, and a negative terminal is provided on the negative electrode side. The positive electrode terminal 2b of the battery cell 2 shown in Figure 1 is also provided with a positive electrode side connection portion 2a for connecting to other batteries (battery cells), etc. In the case of the positive electrode terminal 2b of the battery cell 2 shown in Figure 1, the positive electrode side connection portion 2a is provided on the upper (Z1 side) surface portion of the positive electrode terminal 2b. This positive electrode side connection portion 2a is made of Fe or an Fe alloy. In recent years, in order to realize high-capacity positive electrodes for lithium-ion secondary batteries, there has been a trend towards positive electrode current collectors that take advantage of the excellent alkali resistance of stainless steel, and therefore there is a need for a positive electrode side connection portion 2a (positive electrode terminal 2b) made of the same type of stainless steel.

[0018] In this invention, the notation Fe refers to pure iron or its element symbol with a carbon (C) content of 0.02% by mass or less, and the notation Fe alloy refers to an alloy based on Fe.Specific examples of Fe or Fe alloys include pure iron such as electrolytic iron, Armco iron, carbonyl iron, and reduced iron; electromagnetic soft iron such as the JIS standard SUY series and A series; various stainless steels such as ferritic (JIS standard SUS430, etc.) and austenitic (JIS standard SUS304, SUS316L, etc.); and cold-rolled steel sheets such as JIS standard SPCD for drawing, SPCE, SPCF, and SPCG for deep drawing.

[0019] The busbar 3 shown in Figure 1 is positioned above (on the Z1 side) the positive electrode side joint 2a provided on the positive electrode terminal 2b of the battery cell 2. A busbar side joint 3a is provided on the lower part (on the Z2 side) of this busbar 3. This busbar side joint 3a is made of Al or an Al alloy. In recent years, busbars made of relatively high-strength materials such as Fe or Fe alloy, Ni or Ni alloy, and Cu or Cu alloy are being replaced by busbars made of Al or Al alloy, which can reduce the weight of automotive battery systems and portable device batteries, and there is a need to address this change.

[0020] In this invention, the notation Al refers to pure aluminum (Al) containing 99.5% by mass or more, or the element symbol, while the notation Al alloy refers to an alloy based on Al. Specific examples of Al or Al alloys include, for instance, the A1000 series (pure aluminum) such as A1050 and A1100, which have excellent conductivity as defined in JIS-H4000:2014; the A3000 series (Al-Mn system) such as A3003, which has higher strength than pure aluminum; the A4000 series (Al-Si system) such as A4032 and A4043, which have a lower coefficient of thermal expansion than pure aluminum; and the A5000 series (Al-Mg system) such as A5052, which has even higher strength.

[0021] The conductive connector 10 shown in Figure 1 is positioned between the positive electrode side joint 2a and the busbar side joint 3a of the battery cell 2. As shown in Figure 2, this conductive connector 10 is made of a clad material formed by rolling and bonding an Fe layer 11 made of Fe or an Fe alloy and an Al layer 12 made of Al or an Al alloy. The conductive connector 10 shown in Figure 2 is the conductive connector 10 before it is incorporated into the conductive connector structure 1 shown in Figure 1. The Fe layer 11 of this conductive connector 10 is made of a material equivalent to or approximately equivalent to the conductive metal that constitutes the positive electrode side joint 2a. The Al layer 12 of this conductive connector 10 is made of a material equivalent to or approximately equivalent to the conductive metal that constitutes the busbar side joint 3a.

[0022] Note that the conductive connector 10 shown in Figure 2 is a side view from its side (hereinafter referred to as the X1 side), and its contour is rectangular. However, the contour of the conductive connector according to this invention is not limited to a rectangle, and can be designed to have irregular shapes with irregularities as needed. This point will be explained later with an example of another configuration. Also, although not shown in the illustration, the conductive connector 10 shown in Figure 2 has a circular contour in a plan view from its Z1 side. However, the contour of the conductive connector according to this invention is not limited to a circle, and can be designed to have an elliptical, square, or irregular shape with irregularities as needed.

[0023] Herein, a method for manufacturing a conductive connecting component according to this invention will be described. The conductive connecting component according to this invention can be manufactured by producing a clad material in which an Fe layer and an Al layer are rolled and joined by a conventional dissimilar metal rolling and joining process, and then processing and forming the clad material into a desired shape. Specifically, a clad material in which an Fe layer and an Al layer are rolled and joined can be manufactured by a dissimilar metal rolling and joining process that includes at least a clad rolling process in which an Fe plate made of Fe or an Fe alloy and an Al plate made of Al or an Al alloy are rolled and joined in a laminated state, and a diffusion annealing process in which the clad material after the clad rolling process is heated and held to produce appropriate metal diffusion.

[0024] Next, using the clad material as the base material, conductive connection parts can be manufactured by selecting processing methods as needed, such as wire cutting, punching and forming using a press, cutting and grinding using an end mill, lathe or grinding machine, laser trimming, etching, and peeling, and then processing and forming the clad material into the desired shape.

[0025] The above-mentioned rolling and joining process for dissimilar metals includes manufacturing steps such as softening annealing and intermediate rolling before rolling and joining, softening annealing and intermediate rolling after rolling and joining, finish rolling to obtain the desired thickness, width, surface properties and various characteristics of the product, skin pass rolling, annealing for stress relief, surface treatment, and stripping. Several manufacturing steps can be selected as needed.

[0026] The conductive connection structure 1 shown in Figure 1 has a first joint 4 that connects the conductive connection component 10 and the positive electrode side joint 2a. The first joint 4 shown in Figure 1 is an elongated fusion weld (positive electrode side fusion weld) formed by laser welding, which enables high-speed and low-distortion welding with a clean bead. The type of laser light (CO2, YAG, semiconductor, disk, fiber, etc.) and the medium of the laser light (gas, solid) used for this laser welding can be selected as needed. The laser welding for forming the first joint 4 is preferably keyhole welding, which can form a high-quality, elongated fusion weld with greater precision and stability than thermal conduction welding, with deeper penetration.

[0027] In the conductive connection structure 1 shown in Figure 1, the first joint portion 4 is arranged in an annular, continuous or discontinuous manner in the region on the outer edge side of the conductive connection component 10. This region on the outer edge side of the conductive connection component 10 corresponds to the first joint region 10a of the conductive connection component 10 (see Figure 2) or the region inside it. Note that a configuration in which the bead formed by laser welding is continuous with the surface is called a continuous arrangement, and a configuration in which the bead is not continuous with the surface (for example, a roughly dotted, roughly dotted line, roughly dashed line, etc.) is called a discontinuous arrangement.

[0028] As described above, by positioning the first joint portion 4 in the region on the outer edge side of the conductive connection component 10, even if the connection of the conductive connection component 10 to the busbar 3 by laser welding or the like is performed first, the connection of the conductive connection component 10 to the positive electrode side joint portion 2a by laser welding can be easily performed. Furthermore, if the connection of the conductive connection component 10 to the positive electrode side joint portion 2a by laser welding is performed first, by positioning the first joint portion 4 in a region other than the busbar side joint region 10b (see Figure 2) of the conductive connection component 10, the connection of the conductive connection component 10 to the busbar 3 by laser welding or the like can be easily performed.

[0029] The conductive connection structure 1 shown in Figure 1 has a second joint 5 that connects the conductive connection component 10 and the busbar-side joint 3a. The second joint 5 shown in Figure 1 is preferably a fusion-welded joint (busbar-side fusion-welded joint) formed by laser welding, similar to the first joint 4. The second joint 5 may be formed by other connection means other than laser welding, if necessary. For example, it may be formed by other connection means such as ultrasonic welding, friction diffusion bonding, wire bonding, and bolting.

[0030] In the conductive connection structure 1 shown in Figure 1, the second joint 5 is arranged continuously or discontinuously in the central region of the conductive connection component 10, that is, inside the first joint 4. This central region of the conductive connection component 10 corresponds to the second joint region 10b of the conductive connection component 10 (see Figure 2). The position of the second joint 5 can be determined after the position of the first joint 4 has been determined. A configuration in which the connection portion, such as a fusion weld in laser welding, is continuous with the surface is called a continuous arrangement, while a configuration in which the connection portion is not continuous with the surface (for example, a roughly dotted, roughly dotted line, roughly dashed line, etc.) is called a discontinuous arrangement.

[0031] The conductive connection structure 1 shown in Figure 1 has a fusion mark 6 on the upper (Z1 side) surface portion of the conductive connection component 10. This fusion mark 6 is formed when the conductive connection component 10 and the positive electrode side joint portion 2a are connected by laser welding to form the first joint portion 4. For example, in keyhole welding, where the power density of the laser light is higher than that of thermal conduction welding, the laser light evaporates the surface portion within the laser receiving area 10c (see Figure 2) of the conductive connection component 10, forming a small depression, and further melts the metal directly below that depression, forming an even more elongated cavity (keyhole) than in thermal conduction welding. Then, the molten metal solidifies in that elongated cavity, forming a fusion joint that is more elongated than that of thermal conduction welding. The exposed portion of this elongated fusion joint on the Z1 side surface is the fusion mark 6, and the elongated fusion joint formed extending from the fusion mark 6 toward the Z2 side is the first joint portion 4. Therefore, the fusion marks 6 are located on the surface of the conductive connector 10 opposite to the first joint 4 in the thickness direction (Z direction) (Z1 side). And, similar to the first joint 4, the fusion marks 6 are arranged in annular, continuous or discontinuous manner in the region on the outer edge side of the conductive connector 10.

[0032] The conductive connection structure 1 shown in Figure 1 is an example of a conductive connection structure applicable to the positive electrode side of a battery, configured by connecting a positive electrode side connection portion 10a made of Fe or an Fe alloy, which is provided on the positive electrode side of the battery cell 2, and a busbar side connection portion 10b made of Al or an Al alloy, which is provided on the busbar 3 side, via a conductive connection component 10 made of a clad material formed by rolling and bonding an Fe layer 11 made of Fe or an Fe alloy and an Al layer 12 made of Al or an Al alloy, as described above.

[0033] The conductive connection component 10 before being incorporated into the conductive connection structure 1 shown in Figure 1 may be, for example, the conductive connection component 10 shown in Figure 2. The conductive connection component 10 shown in Figure 2 is made of a clad material formed by rolling and joining an Fe layer 11 made of Fe or an Fe alloy and an Al layer 12 made of Al or an Al alloy. The conductive connection component 10 shown in Figure 2 has a first joining region 10a, a second joining region 10b, and a laser light receiving region 10c.

[0034] The first bonding region 10a of the conductive connecting component 10 shown in Figure 2 is provided on the lower (Z2 side) surface portion along the rolling direction (Y direction) of the Fe layer 11. This first bonding region 10a can be set in an annular shape on the outer edge surface portion of the conductive connecting component 10, for example, assuming the arrangement of the first joint portion 4 of the conductive connecting structure 1 shown in Figure 1. This first bonding region 10a can be subjected to the laser welding described above to the positive electrode side joint portion 2a of the battery cell 2. The first joining region 10a, which is capable of laser welding, is the lower (Z2 side) surface portion of the conductive connector 10, and it is possible to obtain a contact state with virtually no gap with respect to the positive electrode side joining portion 2a. When laser light is incident from the surface of the conductive connector 10 on the opposite side (Z1 side) from the first joining region 10a (laser light receiving region 10c), it is possible to obtain a through-melting state by melting from the surface (Z1 side) of the conductive connector 10 toward the interior (Z2 side), and the configuration is intended to have a shape and properties that do not hinder the formation of the elongated fusion-welded portion (first joining portion 4) as described above.

[0035] The second bonding region 10b of the conductive connecting component 10 shown in Figure 2 is provided on the upper (Z1 side) surface portion of the Al layer 12 along the rolling direction (Y direction). This second bonding region 10b can be set in an annular shape on the central surface portion of the conductive connecting component 10, that is, inside the first bonding region 10a in the rolling direction (Y direction), and on the surface portion of the Al layer 12 opposite to the first bonding region 10a in the thickness direction (X direction) (Z1 side), assuming the arrangement of the second bonding portion 5 of the conductive connecting structure 1 shown in Figure 1. This second bonding region 10b can be bonded to the busbar side bonding portion 3a of the busbar 3 by the above-described bonding means such as laser welding. The second joining region 10b, which can be joined by connection means such as laser welding, is, for example, the upper (Z1 side) surface portion of the conductive connecting component 10 in the case of laser welding, and is intended to have a form and properties that do not hinder the formation of the elongated fused joint (second joining portion 5) as described above by melting and penetrating the busbar-side joining portion 3a and then entering the second joining region 10b, causing the laser light to melt from the surface (Z1 side) to the interior (Z2 side) of the conductive connecting component 10.

[0036] The laser receiving region 10c of the conductive connection component 10 shown in Figure 2 is provided on the surface of the Al layer 12 on the opposite side (Z1 side) from the first bonding region 10a in the thickness direction (Z direction) of the conductive connection component 10, which is a clad material. This laser receiving region 10c can be set in an annular shape on the surface of the Al layer 12 on the outer edge side in the rolling direction (Y direction) of the conductive connection structure 1 shown in Figure 1, for example. This laser receiving region 10c is capable of receiving laser light. The laser receiving region 10c capable of receiving laser light is a surface of the conductive connection component 10 that is open toward the upper side (Z1 side) and is intended to have a shape and properties that do not hinder the formation of the first bonding portion 4 and the fusion mark 6 as described above by receiving laser light irradiated from above (Z1 side). An anti-reflective agent for laser light may be applied to the surface of this laser receiving region 10c.

[0037] The conductive connection component 10 shown in Figure 2 is configured such that 0 ≤ Ta ≤ Ts / 10, where Ts is the thickness of the Fe layer 11 in the portion where the first bonding region 10a is provided, and Ta is the thickness of the Al layer 12 in the portion where the laser light receiving portion 10c is provided. A conductive connection structure 1 using the conductive connection component 10 having a configuration that satisfies 0 ≤ Ta ≤ Ts / 10 can be obtained, which has a desirable connection strength (joint strength).

[0038] For example, it becomes possible to obtain a tensile breaking load of 600 N or more (preferably 650 N or more) between the positive electrode side (Z2 side) and the conductive connecting component 10 in the thickness direction (Z direction) of the conductive connecting component 10. Furthermore, it becomes possible to suppress the tensile breaking stress generated between the positive electrode side (Z2 side) and the conductive connecting component 10 in the thickness direction (Z direction) of the conductive connecting component 10 to 250 MPa or more (preferably 280 MPa or more, more preferably 300 MPa or more). This point has been confirmed in experiments described later. Note that this tensile breaking stress is the value obtained by dividing the above-mentioned tensile breaking load by the penetration cross-sectional area St of the first joint 4 relative to the positive electrode side joint 2a (see Figure 3). The penetration cross-sectional area St of the first joint 4 will be described later.

[0039] In the conductive connection component 10 shown in Figure 2, when 0 ≤ Ta ≤ Ts / 10 is satisfied, the thickness of the Al layer 12 in the portion where the laser light receiving portion 10c is provided is 0 or greater (Ta ≥ 0), and the thickness of the Fe layer 11 in the portion where the first bonding region 10a is provided is 1 / 10 or less (Ta ≤ Ts / 10). The portion where the laser light receiving portion 10c is provided is the surface portion of the cladding material constituting the conductive connection component 10 on the opposite side (Z1 side) from the first bonding region 10a in the thickness direction (Z direction).

[0040] If Ta is greater than 0 (Ta>0), it means that the Al layer 12 is present on the surface portion of the conductive connector 10 opposite to the first bonding region 10a (Z1 side). Therefore, in this case, the laser light receiving region 10c can be set on the Z1 side surface portion of the Al layer 12. Note that in the conductive connector 10 shown in Figure 2, the Al layer 12 is present in the portion where the laser light receiving portion 10c is provided, so Ta is greater than 0 (Ta>0).

[0041] Furthermore, when Ta is 0 (Ta=0), it means that the Al layer 12 is not present on the surface portion of the conductive connector 10 opposite to the first bonding region 10a (Z1 side). This is because, during the manufacturing of the conductive connector 10 from the clad material, the Al layer 12, which was roll-bonded to the upper side (Z1 side) of the Fe layer 11, was partially removed, resulting in the surface portion of the conductive connector 10 opposite to the area intended to be set as the first bonding region 10a (Z1 side) becoming the Fe layer 11. Therefore, in this case, the laser light receiving region 10c can be set on the Z1 side surface portion of the Fe layer 11.

[0042] When constructing the conductive connection structure 1 shown in Figure 1, the conductive connection component 10 satisfying the above-mentioned 0 ≤ Ta ≤ Ts / 10 and the positive electrode side joint 2a are connected by laser welding (preferably keyhole welding) to form the first joint 4, thereby making the first joint 4 an elongated fusion weld (positive electrode side fusion weld). When the first joint 4 is an elongated fusion weld, the penetration width and penetration cross-sectional area of ​​the first joint 4 relative to the positive electrode side joint 2a are relatively small, but the penetration depth of the first joint 4 relative to the positive electrode side joint 2a is suitably large. By ensuring a moderately small penetration width and penetration cross-sectional area of ​​the first joint 4 relative to the positive electrode side joint 2a, it is possible to suppress deterioration of the mechanical properties of the positive electrode side (positive electrode terminal 2b) caused by melting and solidification while ensuring adequate connection strength (joint strength). By suitably increasing the penetration depth of the first joint 4 into the positive electrode side joint 2a, a relatively large connection strength (joint strength) can be obtained between the positive electrode side joint 2a (i.e., the positive electrode terminal 2b) and the conductive connecting component 10, even when the penetration width of the first joint 4 into the positive electrode side joint 2a is relatively small.

[0043] Figure 3 is a schematic diagram showing a cross-section obtained by cutting the conductive connector 10 along the thickness direction (Z direction) near the first joint 4 shown in Figure 1. In this invention, in a cross-sectional view along the thickness direction (Z direction) of the conductive connector 10 passing through the center (center line Lc) of the fusion mark 6, the length of the line segment where the boundary line Lb between the positive electrode side joint 2a and the conductive connector 10 intersects the first joint 4 is considered as the fusion width of the first joint 4 with respect to the positive electrode side joint 2a, and the penetration width Wt of the first joint 4 with respect to the positive electrode side joint 2a is defined.

[0044] Furthermore, if the fusion mark 6 viewed from above (Z1 side) is a discontinuous point shape (approximately circular, elliptical, square, hexagonal, etc.), a circle with a diameter equal to the penetration width Wt is assumed, and the equivalent cross-sectional area of ​​that circle is taken as the penetration cross-sectional area St of the first joint 4 relative to the positive electrode side joint 2a. Alternatively, if the fusion mark 6 viewed from above (Z1 side) is a continuous line (bead), the cross-sectional area obtained by multiplying the penetration width Wt by the length of that line (bead) is taken as the penetration cross-sectional area St of the first joint 4 relative to the positive electrode side joint 2a. If there are multiple effective fusion marks 6, the sum of the penetration cross-sectional areas of each of the effective fusion marks 6 is taken as the penetration cross-sectional area St of the first joint 4 relative to the positive electrode side joint 2a.

[0045] Furthermore, the boundary line Lb is defined as the line (straight line) that appears roughly linear on the interface surface Sb along the rolling direction (Y direction) of the conductive connection component 10 when the conductive connection component 10 is cut along the thickness direction (Z direction) so as to pass through the center (center line Lc) of the fusion mark 6. The direction in which the boundary line Lb intersects the first joint 4 is the rolling direction (Y direction) of the conductive connection component 10. The interface surface Sb between the positive electrode side joint 2a and the conductive connection component 10 is defined as the surface portion on the XY plane where the positive electrode side joint 2a and the conductive connection component 10 are in contact around the first joint 4.

[0046] Furthermore, in a cross-sectional view along the thickness direction (Z direction) of the conductive connection component 10, passing through the center (center line Lc) of the fusion mark 6, the length of the longest line segment that is perpendicular to the boundary line Lb between the positive electrode side joint 2a and the conductive connection component 10 and intersects the first joint 1 is defined as the penetration depth Dp of the first joint 4 relative to the positive electrode side joint 2a. The direction perpendicular to the boundary line Lb and intersecting the first joint 1 is the thickness direction (Z direction) of the conductive connection component 10.

[0047] Also, when the center (center line Lc) of the weld mark 6 is such that the weld mark 6 seen from above (Z1 side) is discontinuous and dot-shaped (a shape approximated by a circle, ellipse, square, hexagon, etc.), it is set at the approximate center of the dot-shaped form. Alternatively, when the weld mark 6 seen from above (Z1 side) is continuous and linear (bead), a position in the length direction of the linear (bead) is randomly selected, and the center (center line Lc) of the weld mark 6 is set at the approximate center in the width direction of the selected location. Also, the center of the first joint portion 4 is regarded as overlapping with the center of the weld mark 6 in the thickness direction (Z direction) of the conductive connection component 10 and is assumed to be located on the center line Lc.

[0048] In the first joint portion 4 of the conductive connection structure 1 shown in FIGS. 1 and 3, the penetration depth Dp of the first joint portion 4 with respect to the positive electrode side joint portion 2a is preferably moderately large. For example, it is preferably 0.20 mm or more. Also, the penetration width Wt and the penetration cross-sectional area St of the first joint portion 4 with respect to the positive electrode side joint portion 2a are preferably ensured moderately even if they are relatively small. For example, the penetration cross-sectional area St is preferably 1.2 mm 2 or more, and more preferably 1.3 mm 2 or more. Thereby, the positive electrode side joint portion 2a (that is, the positive electrode terminal 2b) and the conductive connection component 10 can be made into a joint structure having a suitable connection strength (joint strength) with a large tensile breaking load in the thickness direction (Z direction) (for example, 600 N or more, preferably 650 N or more) and a small tensile breaking stress in the thickness direction (Z direction) (for example, 250 MPa or more, preferably 280 MPa or more, more preferably 300 MPa or more).

[0049] And if the second joint portion 5 is an elongated welded portion similar to the first joint portion 4 formed by laser welding (preferably keyhole welding), or if the bus bar 3 and the conductive connection component 10 are firmly connected even by connection means other than laser welding, the bus bar side joint portion 3a (that is, the bus bar 3) and the conductive connection component 10 can be made into a joint structure having a suitable connection strength (joint strength).

[0050] In this way, the positive electrode side joint 2a and the conductive connecting component 10 are firmly connected at the first joint 4, and the busbar side joint 3a and the conductive connecting component 10 are firmly connected at the second joint 5. As a result, the joint structure formed by the positive electrode side joint 2a (i.e., positive electrode terminal 2b) and the busbar side joint 3a (i.e., busbar 3) via the conductive connecting component 10 can be made into a conductive connection structure 1 having a large tensile breaking load and a small tensile breaking stress, resulting in a suitable connection strength (joint strength).

[0051] Next, regarding embodiments of the conductive connecting component according to this invention, several configuration examples will be given in which the shape differs from that of the conductive connecting component 10 shown in Figure 2 when viewed from the X1 side.

[0052] <Example 1> The conductive connector 20 shown in Figure 4 is made of a clad material formed by rolling and joining an Fe layer 21 made of Fe or an Fe alloy and an Al layer 22 made of Al or an Al alloy, similar to the conductive connector 10 described above. This conductive connector 20 has a first bonding region 20a, a second bonding region 20b, and a laser light receiving region 20c.

[0053] In a side view, the conductive connector 20 has a contour that is smaller on the upper side (Z1 side) and larger on the lower side (Z2 side), with a convex shape towards the upper side (Z1 side). Although not shown in the illustration, in a plan view, the contour of the conductive connector 20 may be the same shape as the conductive connector 10 described above, or it may be a different shape. When manufacturing the conductive connector 20 from the clad material, the central part of the Al layer 22 is processed and molded so that it has a convex shape in the thickness direction (Z direction). This convex shape of the Al layer 22 can be processed and molded by a manufacturing method that partially removes the Al layer 22 that was roll-bonded to the upper side (Z1 side) of the Fe layer 21, or by a manufacturing method that partially compresses and molds the Al layer 22 using a press or the like to partially reduce its thickness.

[0054] The first bonding region 20a of the conductive connector 20 is provided on the lower (Z2 side) surface portion of the Fe layer 21 along the rolling direction (Y direction). This first bonding region 20a can be set, for example, in an annular shape on the outer edge surface portion of the conductive connector 20. This first bonding region 20a can be laser-welded to the mating joint (for example, the positive electrode side joint 2a) as described above.

[0055] The second bonding region 20b of the conductive connecting component 20 is provided on the upper (Z1 side) surface portion of the Al layer 22 along the rolling direction (Y direction). This second bonding region 20b can be set in an annular shape on the central surface portion of the conductive connecting component 20, that is, inside the first bonding region 20a in the rolling direction (Y direction) and on the surface portion of the Al layer 22 opposite to the first bonding region 20a in the thickness direction (X direction) (Z1 side). This second bonding region 20b can be bonded to the mating bonding portion (for example, the busbar side bonding portion 3a) by a bonding means such as the laser welding described above.

[0056] The laser receiving region 20c of this conductive connection component 20 is provided on a partially thinner surface of the Al layer 22 on the opposite side (Z1 side) from the first bonding region 20a in the thickness direction (Z direction) of the conductive connection component 20, which is a cladding material. This laser receiving region 20c can be set in an annular shape on the surface of the Al layer 22 on the outer edge side in the rolling direction (Y direction) of the conductive connection structure 1 shown in Figure 1. This laser receiving region 20c is capable of receiving laser light. The surface of this laser receiving region 20c may be coated with an anti-reflective agent for laser light.

[0057] The conductive connector 20 is configured such that 0 ≤ Ta ≤ Ts / 10, where Ts is the thickness of the Fe layer 21 in the portion where the first bonding region 20a is provided, and Ta is the thickness of the Al layer 22 in the portion where the laser light receiving portion 20c is provided. In this conductive connector 20, since the Al layer 22 is present in the portion where the laser light receiving portion 20c is provided, Ta is greater than 0 (Ta > 0). A conductive connection structure using a conductive connector 20 having a configuration that satisfies 0 ≤ Ta ≤ Ts / 10 can have a desirable connection strength (joint strength), similar to the conductive connection structure 1 shown in Figure 1.

[0058] <Modification 2> The conductive connector 30 shown in Figure 5 is made of a clad material formed by rolling and joining an Fe layer 31 made of Fe or an Fe alloy and an Al layer 32 made of Al or an Al alloy, similar to the conductive connector 10 described above. This conductive connector 30 has a first bonding region 30a, a second bonding region 30b, and a laser light receiving region 30c.

[0059] Similar to the conductive connecting component 20 described above, the conductive connecting component 30, in a side view, has a contour that is smaller on the upper side (Z1 side) and larger on the lower side (Z2 side), with a convex shape on the upper side (Z1 side). Although not shown in the figures, in a plan view, the contour of the conductive connecting component 30 may be the same shape as the conductive connecting component 20 described above, or it may be a different shape. When the conductive connecting component 30 is manufactured from the clad material, the outer edge portion of the Al layer 32 is removed in an annular shape in the rolling direction (Y direction), and the central portion of the Al layer 32 that was not removed is processed and molded so that it has a convex shape in the thickness direction (Z direction). This convex shape of the Al layer 32 can be processed and molded by a manufacturing method that partially removes the Al layer 32 that was roll-bonded to the upper side (Z1 side) of the Fe layer 31.

[0060] The first bonding region 30a of the conductive connector 30 is provided on the lower (Z2 side) surface portion of the Fe layer 31 along the rolling direction (Y direction). This first bonding region 30a can be set in an annular shape, for example, on the outer edge surface portion of the conductive connector 30. This first bonding region 30a can be laser-welded to the mating joint (for example, the positive electrode side joint 2a) as described above.

[0061] The second bonding region 30b of the conductive connecting component 30 is provided on the upper (Z1 side) surface portion of the Al layer 32 along the rolling direction (Y direction). This second bonding region 30b can be set in an annular shape, for example, on the central surface portion of the conductive connecting component 30, that is, inside the first bonding region 30a in the rolling direction (Y direction) and on the surface portion of the Al layer 32 opposite to the first bonding region 30a in the thickness direction (X direction) (Z1 side). This second bonding region 30b can be bonded to the mating bonding portion (for example, the busbar side bonding portion 3a) by the above-described bonding means such as laser welding.

[0062] The laser receiving region 30c of this conductive connection component 30 is provided on the surface of the Fe layer 31 exposed by removing the Al layer 32 on the opposite side (Z1 side) from the first bonding region 30a in the thickness direction (Z direction) of the conductive connection component 30, which is a clad material. This laser receiving region 30c can be set to an annular shape, for example, assuming the arrangement of the fusion marks 6 of the conductive connection structure 1 shown in Figure 1. This laser receiving region 30c is capable of receiving laser light. The surface of this laser receiving region 30c may be coated with an anti-reflective agent for laser light.

[0063] The conductive connector 30 is configured such that 0 ≤ Ta ≤ Ts / 10, where Ts is the thickness of the Fe layer 31 in the portion where the first bonding region 30a is provided, and Ta is the thickness of the Al layer 32 in the portion where the laser light receiving portion 30c is provided. In this conductive connector 30, the portion where the laser light receiving portion 30c is provided is the surface of the Fe layer 31 exposed by the removal of the Al layer 32, and not the surface of the Al layer 32, so Ta is 0 (Ta=0). In a configuration like this conductive connector 30, where the Al layer 32 does not exist in the portion where the laser light receiving portion 30c is provided, the relationship 0 ≤ Ta ≤ Ts / 10 can be applied by setting Ta to 0 (Ta=0). A conductive connection structure using a conductive connector 30 having a configuration that satisfies 0 ≤ Ta ≤ Ts / 10 can have a desirable connection strength (joint strength), similar to the conductive connection structure 1 shown in Figure 1.

[0064] <Variation 3> The conductive connector 40 shown in Figure 6 is made of a clad material formed by rolling and joining an Fe layer 41 made of Fe or an Fe alloy and an Al layer 42 made of Al or an Al alloy, similar to the conductive connector 10 described above. This conductive connector 40 has a first bonding region 40a, a second bonding region 40b, and a laser light receiving region 40c.

[0065] In a side view, the conductive connector 40 has a contour similar to that of the conductive connector 10 described above. Although not shown in the illustration, in a side view of the cross-section along the thickness direction (Z direction), the central part on the upper side (Z1 side) is concave on the lower side (Z2 side). In a plan view, although not shown in the illustration, the contour of the conductive connector 40 may be similar to that of the conductive connector 10 described above, or it may be a different shape. When manufacturing the conductive connector 40 from the clad material, the central part of the Al layer 42 is processed and molded so that it is concave in the thickness direction (Z direction). This concave shape of the Al layer 42 can be processed and molded by a manufacturing method that partially removes the Al layer 42 that was roll-bonded to the upper side (Z1 side) of the Fe layer 41, or by a manufacturing method that partially compresses and molds the Al layer 42 using a press or the like to partially reduce its thickness.

[0066] The first bonding region 40a of the conductive connector 40 is provided on the lower (Z2 side) surface portion of the Fe layer 41 along the rolling direction (Y direction). This first bonding region 40a can be set in an annular shape, for example, on the outer edge surface portion of the conductive connector 40. This first bonding region 40a can be laser welded to the mating joint (for example, the positive electrode side joint 2a) as described above.

[0067] The second bonding region 40b of this conductive connecting component 40 is provided on the surface portion of the central upper (Z1 side) of the Al layer 42 along the rolling direction (Y direction). That is, this second bonding region 40b can be set on the bottom surface portion of a partially thinner concave shape of the Al layer 42, which is inside the first bonding region 40a in the rolling direction (Y direction) and on the opposite side (Z1 side) from the first bonding region 40a in the thickness direction (X direction). This second bonding region 40b can be bonded to the mating bonding portion (for example, the busbar side bonding portion 3a) by a bonding means such as the laser welding described above.

[0068] The laser receiving region 40c of this conductive connection component 40 is provided on the surface of the Al layer 42 on the opposite side (Z1 side) from the first bonding region 40a in the thickness direction (Z direction) of the conductive connection component 40, which is a clad material. This laser receiving region 40c can be set in an annular shape on the surface of the Al layer 42 on the outer edge side in the rolling direction (Y direction) of the conductive connection structure 1 shown in Figure 1. This laser receiving region 40c is capable of receiving laser light. An anti-reflective agent for laser light may be applied to the surface of this laser receiving region 40c.

[0069] The conductive connector 40 is configured such that 0 ≤ Ta ≤ Ts / 10, where Ts is the thickness of the Fe layer 41 in the portion where the first bonding region 40a is provided, and Ta is the thickness of the Al layer 42 in the portion where the laser light receiving portion 40c is provided. In this conductive connector 40, since the Al layer 42 is present in the portion where the laser light receiving portion 40c is provided, Ta is greater than 0 (Ta > 0). A conductive connection structure using the conductive connector 40 having a configuration that satisfies 0 ≤ Ta ≤ Ts / 10 can have a desirable connection strength (joint strength), similar to the conductive connection structure 1 shown in Figure 1.

[0070] <Modification 4> The conductive connecting component 50 shown in Figure 7 is made of a clad material formed by rolling and joining an Fe layer 51 made of Fe or an Fe alloy and an Al layer 52 made of Al or an Al alloy, similar to the conductive connecting component 10 described above. This conductive connecting component 50 has a first bonding region 50a, a second bonding region 50b, and a laser light receiving region 50c.

[0071] In a side view, the conductive connector 50 has a contour that is smaller on the upper side (Z1 side) and larger on the lower side (Z2 side), with one side of the upper side (Z1 side) (Y1 side) being a convex stepped shape. Although not shown in the figure, in a plan view, the contour of the conductive connector 50 may be the same shape as the conductive connector 10 described above, or it may be a different shape. When manufacturing the conductive connector 50 from the clad material, the Al layer 52 is processed and molded so that one side (Y1 side) is a convex stepped shape in the thickness direction (Z direction). This convex stepped shape of the Al layer 52 can be processed and molded by a manufacturing method that partially removes the Al layer 52 that was roll-bonded to the upper side (Z1 side) of the Fe layer 51, or by a manufacturing method that partially compresses and molds the Al layer 52 using a press or the like to partially reduce its thickness.

[0072] The first bonding region 50a of the conductive connecting component 50 is provided on the lower (Z2 side) surface portion along the rolling direction (Y direction) of the Fe layer 51. This first bonding region 50a can be set on the surface portion between the central part of the conductive connecting component 50 and one edge side (Y2 side). This first bonding region 50a can be subjected to the laser welding described above to the mating bonding portion (for example, the positive electrode side bonding portion 2a).

[0073] The second bonding region 50b of the conductive connecting component 50 is provided on the upper (Z1 side) convex stepped surface portion of the Al layer 52 along the rolling direction (Y direction). This second bonding region 50b can be set on one side (Y1 side) of the conductive connecting component 50, that is, on the surface portion of the Al layer 52 that is opposite to the first bonding region 50a in the rolling direction (Y direction) (Y1 side) and opposite to the first bonding region 50a in the thickness direction (Z direction) (Z1 side). This second bonding region 50b can be bonded to the mating bonding portion (for example, the busbar side bonding portion 3a) by a bonding means such as the laser welding described above.

[0074] The laser light receiving region 50c of this conductive connector 50 is located on a surface where the thickness of the Al layer 52 is partially smaller on the opposite side (Z1 side) in the thickness direction (Z direction) from the first bonding region 50a of the conductive connector 50, which is the cladding material. This laser light receiving region 50c is capable of receiving laser light. The laser light receiving region 50c may have an anti-reflective agent applied to its surface.

[0075] The conductive connector 50 is configured such that 0 ≤ Ta ≤ Ts / 10, where Ts is the thickness of the Fe layer 51 in the portion where the first bonding region 50a is provided, and Ta is the thickness of the Al layer 52 in the portion where the laser light receiving portion 50c is provided. In this conductive connector 50, since the Al layer 5 is present in the portion where the laser light receiving portion 50c is provided, Ta is greater than 0 (Ta > 0). A conductive connection structure using the conductive connector 50 having a configuration that satisfies 0 ≤ Ta ≤ Ts / 10 can have a desirable connection strength (joint strength), similar to the conductive connection structure 1 shown in Figure 1.

[0076] <Modification 5> The conductive connector 60 shown in Figure 8 is made of a clad material formed by rolling and joining an Fe layer 61 made of Fe or an Fe alloy and an Al layer 62 made of Al or an Al alloy, similar to the conductive connector 10 described above. This conductive connector 60 has a first bonding region 60a, a second bonding region 60b, and a laser light receiving region 60c.

[0077] Similar to the conductive connecting component 50 described above, the conductive connecting component 60, in a side view, has a contour that is smaller on the upper side (Z1 side) and larger on the lower side (Z2 side), with one side of the upper side (Z1 side) (Y1 side) being a convex stepped shape. Although not shown in the figure, in a plan view, the contour of the conductive connecting component 60 may be the same shape as the conductive connecting component 50 described above, or it may be a different shape. When manufacturing the conductive connecting component 60 from the clad material, one side (Y2 side) of the Al layer 62 is removed from near the center in the rolling direction (Y direction), and the opposite side (Y1 side) of the remaining Al layer 62 from near the center becomes a convex stepped shape in the thickness direction (Z direction). This convex stepped shape of the Al layer 62 can be processed and formed by a manufacturing method that partially removes the Al layer 62 that was roll-bonded to the upper side (Z1 side) of the Fe layer 61.

[0078] The first bonding region 60a of the conductive connector 60 is provided on the lower (Z2 side) surface portion along the rolling direction (Y direction) of the Fe layer 61. This first bonding region 60a can be set on the surface portion between the central part of the conductive connector 60 and one edge (Y2 side). This first bonding region 60a can be subjected to the laser welding described above to the mating joint (for example, the positive electrode side joint 2a).

[0079] The second bonding region 60b of the conductive connecting component 60 is provided on the upper (Z1 side) convex stepped surface portion of the Al layer 62 along the rolling direction (Y direction). This second bonding region 60b can be set on one side (Y1 side) of the conductive connecting component 60, that is, on the surface portion of the Al layer 62 opposite to the first bonding region 60a in the rolling direction (Y direction) (Y1 side), and opposite to the first bonding region 60a in the thickness direction (Z direction) (Z1 side). This second bonding region 60b can be bonded to the mating bonding portion (for example, the busbar side bonding portion 3a) by a bonding means such as the laser welding described above.

[0080] The laser light receiving region 60c of this conductive connector 60 is located on the surface of the Fe layer 61 exposed by removing the Al layer 62 on the opposite side (Z1 side) in the thickness direction (Z direction) from the first bonding region 60a of the conductive connector 60, which is the cladding material. This laser light receiving region 60c is capable of receiving laser light. The surface of this laser light receiving region 60c may be coated with an anti-reflective agent for laser light.

[0081] The conductive connector 60 is configured such that 0 ≤ Ta ≤ Ts / 10, where Ts is the thickness of the Fe layer 61 in the portion where the first bonding region 60a is provided, and Ta is the thickness of the Al layer 62 in the portion where the laser light receiving portion 60c is provided. In this conductive connector 60, the portion where the laser light receiving portion 60c is provided is the surface of the Fe layer 61 exposed by the removal of the Al layer 62, and not the surface of the Al layer 62, so Ta is 0 (Ta=0). In a configuration like this conductive connector 60, where the Al layer 62 does not exist in the portion where the laser light receiving portion 60c is provided, the relationship 0 ≤ Ta ≤ Ts / 10 can be applied by setting Ta to 0 (Ta=0). A conductive connection structure using a conductive connector 60 having a configuration that satisfies 0 ≤ Ta ≤ Ts / 10 can have a desirable connection strength (joint strength), similar to the conductive connection structure 1 shown in Figure 1. [Examples]

[0082] A joint structure, as shown in Figure 9, which is modeled after an embodiment of the conductive connection structure according to this invention, was actually fabricated, and the effectiveness of the conductive connection component and conductive connection structure according to this invention was evaluated. The results are shown in Table 1.

[0083] [Table 1]

[0084] In this evaluation, joints A to D shown in Table 1 are conductive connection structures in which test specimens 1 to 12, corresponding to conductive connection components, are connected by laser welding to a substrate corresponding to the anode-side joint 2a (positive terminal 2b) shown in Figure 1. The fusion welds (three beads) of joints A to D correspond to the first joint 4 shown in Figure 1. The contact surface between test specimens 1 to 12 and the substrate corresponds to the interface Sb shown in Figure 3, and in a cross-sectional view along the thickness direction (Z direction), it corresponds to the boundary equivalent line Lb. The three fusion welds (beads) formed on the Z1 side surface by laser welding correspond to the fusion weld marks 6 shown in Figure 1. Laser welding was performed using an Amada Weldtech fiber laser welding machine (MF-C1000A-S) with a theoretical focusing diameter of 23.9 μm, an output of 300 W, and a welding speed of 500 mm per second.

[0085] In Table 1, the test specimen for joint A has an Fe layer and no Al layer (Ta=0). The test specimens for joints B to D are constructed by layering an Fe layer and an Al layer. In all cases of joints A to D, the Fe layer of the test specimen is made of a stainless steel plate equivalent to SUS430, with a length of 100 mm, a width of 30 mm, and a thickness of 0.200 mm as shown in Table 1. In all cases of joints A to D, the Al layer of the test specimen is made of an aluminum plate equivalent to A1050, with a length of 50 mm, a width of 30 mm, and a thickness as shown in Table 1. In all cases of joints A to D, the substrate for constructing the above-mentioned test specimen (conductive connection part) and joint structure (conductive connection structure) is made of a stainless steel plate equivalent to SUS430, with a length of 100 mm, a width of 30 mm, and a thickness of 0.300 mm. From this point forward, joints A through D will have a total length of 150 mm, a total width of 30 mm, and an overlapping section length of 50 mm.

[0086] The penetration depth Dp and penetration width Wt of the fusion joint shown in Table 1 were determined by cutting the joint, which has a total width of 30 mm, along the YZ plane near the center in the width direction, and observing the cross-section. In the observed cross-section, the penetration depth Dp and penetration width Wt of the three fusion joints corresponding to the three beads (corresponding to fusion marks 6) were measured, and the average value was calculated. This average value was then used as the penetration depth Dp and penetration width Wt of the fusion joint (corresponding to the first joint 4) of the joint. Furthermore, the penetration cross-sectional area St of the fusion joint shown in Table 1 was calculated by considering the total length of the three beads (5.0 mm x 3) as the total length of the fusion joint, and multiplying this total length of the fusion joint by the penetration width Wt.

[0087] The tensile breaking load and tensile breaking stress shown in Table 1 were determined by tensile testing. Specifically, referring to the joint structure shown in Figure 9, the Y1 end of the substrate was gripped with a fixed clamp, and the Y2 end of the test specimen was gripped with a movable clamp. The movable clamp was moved toward the Y2 side at a constant speed to apply a tensile load. The load at which the fusion joint of the joint broke was determined and defined as the tensile breaking load. The tensile breaking stress was then determined by dividing the tensile breaking load obtained in the tensile test by the penetration cross-sectional area St of the fusion joint. In Table 1, for joint C number 9 and joint D number 12, the test specimen broke away from the substrate before the tensile test, so the tensile breaking load was set to "0" and the tensile breaking stress to "-".

[0088] The joint A shown in Table 1 is a joint structure using test specimens 1 to 3 that satisfy 0 ≤ Ta ≤ Ts / 10. The penetration depth Dp of joint A using test specimens 1 to 3 was 0.207 mm to 0.260 mm, satisfying Dp ≥ 0.18 mm and more preferably Dp ≥ 0.20 mm. The penetration cross-sectional area St of joint A was 1.335 mm². 2 ~1,620mm 2 Therefore, St≧1.2mm 2 Satisfying the above, and more preferably St≧1.3mm 2 The conditions were also satisfied. Furthermore, the tensile breaking load of joint A was 738N to 772N, which was well above 600N and even above the more preferable 650N. In addition, the tensile breaking stress of joint A was 476MPa to 578MPa, which was significantly higher than 250MPa and well above the more preferable 300MPa. From these results, it was confirmed that joint A with suitable connection strength (joint strength) can be obtained by using test specimens 1 to 3 that satisfy 0 ≤ Ta ≤ Ts / 10.

[0089] The joint B shown in Table 1 is a joint structure using test specimens 4 to 6 that satisfy 0 ≤ Ta ≤ Ts / 10. The penetration depth Dp of joint B using test specimens 4 to 6 was 0.200 mm to 0.245 mm, satisfying Dp ≥ 0.18 mm and more preferably Dp ≥ 0.20 mm. The penetration cross-sectional area St of joint B was 1.740 mm². 2 ~2.175mm2 Therefore, St≧1.2mm 2 Satisfying the above, and more preferably St≧1.3mm 2 The conditions were also satisfied. The tensile breaking load of joint B ranged from 626N to 682N, exceeding 600N, and some even exceeding the more preferable 650N. Furthermore, the tensile breaking stress of joint B ranged from 314MPa to 374MPa, which was significantly higher than 250MPa, considerably higher than the preferable 280MPa, and higher than the more preferable 300MPa. From these results, it was confirmed that joint B with suitable connection strength (joint strength) can be obtained by using test specimens 4 to 6 that satisfy 0 ≤ Ta ≤ Ts / 10.

[0090] The joint C shown in Table 1 is a joint structure using test specimens 7-9 that do not satisfy 0 ≤ Ta ≤ Ts / 10. The penetration depth Dp of joint C using test specimens 7-9 ranged from 0.059 mm to 0.178 mm, failing to satisfy Dp ≥ 0.18 mm. Furthermore, the penetration cross-sectional area St of joint C was 0.765 mm². 2 ~1,050mm 2 Therefore, St≧1.2mm 2 The conditions were not met. The tensile breaking load of joint C ranged from 463N to 525N (test specimen 9 could not be measured), with some not exceeding 600N and others being unmeasurable. The tensile breaking stress of joint C ranged from 500MPa to 605MPa (test specimen 9 could not be calculated), with some well exceeding the more desirable 300MPa, but others being uncalculated, resulting in large variations and unreliable results. From these results, it was confirmed that by using test specimens 7 to 9 that did not satisfy 0≦Ta≦Ts / 10, joint C without sufficient connection strength (joint strength) could be obtained.

[0091] The joint D shown in Table 1 is a joint structure using test specimens 10 to 12 that do not satisfy 0 ≤ Ta ≤ Ts / 10. The penetration depth Dp of joint D using test specimens 10 to 12 was 0.053 mm to 0.080 mm, which did not satisfy Dp ≥ 0.18 mm. In addition, the penetration cross-sectional area St of joint D was 0.705 mm². 2 ~1.125mm 2Therefore, St≧1.2mm 2 The conditions were not met. Furthermore, the tensile breaking load of joint D ranged from 7N to 551N (test specimen 12 could not be measured), with some not exceeding 600N and others being unmeasurable. In addition, the tensile breaking stress of joint D ranged from 6MPa to 602MPa (test specimen 12 could not be calculated), with some well exceeding the more desirable 300MPa, others being extremely small than 250MPa, and some being uncalculated, resulting in large variations and unreliable results. From these results, it was confirmed that by using test specimens 10 to 12 that do not satisfy 0≦Ta≦Ts / 10, joint D without sufficient connection strength (joint strength) can be obtained.

[0092] Based on the above, the conductive connection structures (joints A and B) using conductive connection components (test specimens 1 to 6) that satisfy 0 ≤ Ta ≤ Ts / 10 satisfy the following conditions: the penetration depth Dp of the fusion weld corresponding to the first joint 4 shown in Figure 1 satisfies Dp ≥ 0.18 mm, and the penetration cross-sectional area St is St ≥ 1.2 mm. 2 The requirements were met, the tensile breaking load was 600 N or more (preferably 650 N or more), the tensile breaking stress was 250 MPa or more (preferably 250 MPa or more, more preferably 300 MPa or more), and it was confirmed that the joint strength was suitable. Therefore, this invention is effective. [Explanation of symbols]

[0093] 1: Conductive connection structure 2: Battery cell 2a: Positive electrode side junction 2b: Positive terminal 3: Bus bar 3a: Busbar side connection 4: 1st joint 5:Second joint 6: Fusion weld marks 10, 20, 30, 40, 50, 60: Conductive connectors (clad inserts) 10a, 20a, 30a, 40a, 50a, 60a: First bonding region 10b, 20b, 30b, 40b, 50b, 60b: 2nd junction area 10c, 20c, 30c, 40c, 50c, 60c: Laser light receiving region 11, 21, 31, 41, 51, 61: Fe layer 12, 22, 32, 42, 52, 62: Al layer Ts: Thickness of the Fe layer (Ts≧0) Thickness of the Ta:Al layer (Ta>0) Dp: Dissolution depth Wt: Dissolution width St: Penetration cross-sectional area Lb: Boundary equivalent line Sb: Boundary surface Lc: Center line

Claims

1. A conductive connection structure is constructed by connecting a positive electrode side connection portion made of Fe or Fe alloy, provided on the positive electrode side of a battery, and a busbar side connection portion made of Al or Al alloy, provided on the busbar side, via a conductive connection component made of a clad material formed by rolling and bonding an Fe layer made of Fe or Fe alloy and an Al layer made of Al or Al alloy, by laser welding. The conductive connecting component has a first joint connecting the conductive connecting component and the positive electrode side joint, a second joint connecting the conductive connecting component and the busbar side joint, and a fusion mark on the surface of the conductive connecting component opposite to the first joint in the thickness direction, When the thickness of the Fe layer in the portion with the first joint is Ts, and the thickness of the Al layer in the portion with the fusion mark is Ta, the condition 0 ≤ Ta ≤ Ts / 10 is satisfied, and when the penetration depth of the first joint into the positive electrode side joint is Dp, the condition Dp ≥ 0.18 mm is satisfied. A conductive connection structure in which, when St is the penetration cross-sectional area of ​​the first joint with respect to the positive electrode side joint, St ≥ 1.2 mm² is satisfied, and the tensile breaking load between the positive electrode side joint and the conductive connection component in the thickness direction of the conductive connection component is 600 N or more.

2. The conductive connection structure according to claim 1, wherein the tensile fracture stress between the positive electrode side joint and the conductive connection component in the thickness direction of the conductive connection component is 250 MPa or more.

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