Terminals for secondary batteries and methods for manufacturing secondary battery terminals

Abstract

To provide a terminal for secondary batteries that can maintain electrical and mechanical properties. [Solution] The secondary battery terminal includes a first terminal material made of a first metal, a second terminal material made of a second metal, and a solid-phase joint between the first and second metals. The solid-phase joint joins the first and second terminal materials. The first terminal material includes a first portion on the first side in the first direction. The second terminal material includes a second portion on the second side in the first direction. The second portion covers the first portion and is in contact with the first portion. The first and second terminal materials form an interface between the first and second portions in a covered state where the first portion is covered by the second portion. The interface includes an uneven region having an uneven shape in the first direction. The uneven region includes a first region and a second region. The second region is connected to the first region on the outside in the second direction. The second region has a convex shape on the first side in the first direction compared to the first region, and an annular shape surrounding the outer circumference of the first region. The solid-phase joint is provided in the first region.

Description

Technical Field

[0001] The present invention relates to a terminal for a secondary battery.

Background Art

[0002] Patent Document 1 discloses a terminal component, a secondary battery and a battery pack including the same, and a method for manufacturing the terminal component. The terminal component includes a first metal and a second metal. The first metal includes a shaft portion, an upper end portion, and a caulking portion. The shaft portion has a cylindrical shape. The upper end portion is a flat plate-like part. The caulking portion is caulked to the negative electrode current collector terminal. The second metal is overlapped on the upper end portion of the first metal. The first metal is made of copper, and the second metal is made of aluminum. The first metal has a recess at a portion where the second metal is overlapped. The recess has the following portion. This portion is wider inside than at the opening. The recess of the first metal can be formed by forging or cutting. The recess of the first metal is a substantially frustum-shaped space. The peripheral edge portion of the second metal overlaps with the peripheral edge portion of the upper end portion of the first metal. The second metal has a first fitting portion and a following recess. The first fitting portion enters the recess of the first metal. This recess is formed on the surface opposite to the first fitting portion. The first fitting portion includes a second fitting portion. The second fitting portion enters a portion that is wider than the opening in the depth direction of the recess of the first metal. The second metal contacts the bottom of the recess of the first metal. The second fitting portion engages with the side peripheral surface of the recess of the first metal. With such a configuration, sufficient mechanical fastening strength is ensured between the first metal and the second metal. At least a part of the first fitting portion of the second metal is metallurgically joined to the inner surface of the recess of the first metal. Examples of metallurgical joining include ultrasonic joining, friction pressure welding, diffusion bonding, and resistance welding. Metallurgical joining does not include a mechanical joining state. An example of mechanical joining is caulking.

[0003] Patent Document 1 describes a manufacturing method comprising a first step, a second step, and a third step. The first step involves preparing a first metal. The second step involves preparing a second metal. The third step involves metal-joining the first metal and the second metal. The third step involves placing the second metal on top of the portion of the first metal where a recess has been formed. The third step involves partially pressing the second metal in accordance with the position corresponding to the recess of the first metal, forming a recess in the second metal and causing a portion of the second metal to fit into the next portion of the recess in the first metal. In this portion, the interior becomes wider than the opening of the recess in the first metal. Furthermore, the third step involves metal-joining the next portion of the second metal with the first metal. This portion of the second metal fits into the recess of the first metal. The metal-joining of the first metal and the second metal is performed by ultrasonic pressure welding. The first metal is placed on an anvil. The second metal is placed on top of the surface of the first metal that has a recess. A horn is pressed against the second metal. This causes the anvil and horn to sandwich the first and second metals. The horn is pressed against the position of the second metal corresponding to the opening of the recess in the first metal. The area in which the horn is pressed against the second metal is set inside the opening of the recess. A horn with an area smaller than the opening is used. The horn is mounted on a press machine. The press machine is equipped with a vibration generator. The horn is pressed against the second metal while vibrations required for ultrasonic welding are applied. As a result, the second metal is pressed into the recess of the first metal. As the second metal is pressed into the first metal, it undergoes plastic deformation and penetrates deeply into the recess of the first metal. A recess is formed on the surface of the second metal against which the horn is pressed. Furthermore, a portion of the second metal and the first metal are metallically joined. This portion of the second metal penetrates into the recess of the first metal. As a result, the side surface of the recess in the first metal and the second metal that has entered the recess interlock.

[0004] Patent Document 2 discloses a terminal, a storage battery, and a method for manufacturing the terminal. For example, the terminal is provided on a storage battery as a terminal for the storage battery. The terminal comprises a first terminal portion and a second terminal portion. The first terminal portion has a protrusion on its first contact surface. The second terminal portion has a recess on its second contact surface. The first terminal portion and the second terminal portion are fastened together with their first and second contact surfaces in contact. The protrusion fills the recess when fastened. The first terminal portion has a first protrusion and a second protrusion as protrusions on its first contact surface. The second protrusion is provided on the outer circumference of the first protrusion. The second terminal portion has a first recess and a second recess as recesses on its second contact surface. The first recess is provided at a position on the second contact surface facing the first protrusion when fastened. The second recess is provided at a position on the second contact surface facing the second protrusion when fastened. The first and second protrusions are annular protrusions. The first and second recesses are annular recesses. The first protrusion fills the first recess when fastened. The second protrusion is filled into the second recess when fastened. The first terminal portion has a shape in which the axial second end protrudes radially. The first terminal portion includes a restrained portion. The restrained portion includes the radially protruding portion and forms the axial second end of the first terminal portion. The restrained portion includes a first contact surface. The restrained portion is frustoconical in shape, widening from the axial first side to the second side. The second terminal portion includes a bottomed cylindrical restraining portion. The restraining portion accommodates the restrained portion. The bottom surface of the restraining portion forms the second contact surface. The side walls of the restraining portion become crimping portions. The crimping portions restrain the outer circumference of the restrained portion housed in the restraining portion.

[0005] Patent Document 2 describes a manufacturing method in which a first member and a second member are plastically deformed using a set of molds attached to a processing device. The manufacturing method includes a receiving step, a crimping step, and a filling step. After the receiving step is completed, the manufacturing method proceeds to the crimping step and the filling step. The first member forms a first terminal portion. The first surface of the first member becomes the first contact surface. The second member forms a second terminal portion. The second surface of the second member becomes the second contact surface. A recess is formed on the second surface of the second member. A bottomed cylindrical portion is formed on the second member. The cylindrical portion has the second surface of the second member as its bottom surface. The receiving step involves receiving the end of the first member into the cylindrical portion of the second member and bringing the first and second surfaces into contact. The crimping step involves plastically deforming the side wall portion of the cylindrical portion of the second member toward the end of the first member, and restraining the end of the first member with the side wall portion. The filling step involves plastically deforming the first member with the first surface of the first member and the second surface of the second member in contact. In the filling process, the portion of the first member that undergoes plastic deformation is filled into the recess, and the portion of the first member filling the recess forms a protrusion on the first surface. The filling process is carried out by pressing the first and second members in the axial direction while the first and second surfaces are in contact with each other. The axial direction is perpendicular to the first and second surfaces and is aligned with the direction of the protrusion of the protrusion and the depth direction of the recess. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-120925 [Patent Document 2] Japanese Patent Publication No. 2017-103127 [Overview of the project] [Problems that the invention aims to solve]

[0007] The secondary battery terminal has a first structure and a second structure. In the first structure, the secondary battery terminal includes a first terminal material made of a first metal and a second terminal material made of a second metal, and includes a solid-state joint between the first metal and the second metal. The second metal is different from the first metal. In the second structure, the second terminal material includes a second portion on the second side in the first direction, and the second portion covers and contacts the first portion on the first side of the first terminal material in the first direction. Furthermore, in the second structure, the first terminal material and the second terminal material form an interface between the first portion and the second portion in a covered state where the first portion is covered by the second portion.

[0008] In recent years, extreme heavy rains have been occurring frequently in various regions. Secondary batteries are sometimes installed outdoors. Examples of secondary batteries installed outdoors include vehicle batteries and residential storage batteries. Suppose water penetrates the interface formed between the first part of the first terminal material and the second part of the second terminal material. The water penetrates from the outer edge of this interface. In this case, the penetration of water into the interface can cause galvanic corrosion of the metal with the lower potential among the first and second metals. Suppose the first metal is copper and the second metal is aluminum. Copper includes copper alloys, and aluminum includes aluminum alloys. Between copper and aluminum, aluminum has a lower potential than copper and is more susceptible to galvanic corrosion. When galvanic corrosion occurs at the solid-state junction of the first and second metals, one or both of the electrical and mechanical properties of secondary battery terminals may deteriorate.

[0009] The inventors have investigated a structure for a secondary battery terminal that can prevent galvanic corrosion of the solid-phase joint by water penetration into the interface formed between the first part of the first terminal material and the second part of the second terminal material. Such a structure can contribute to simplifying or omitting the following waterproof structure, and can also be used in combination with waterproof structures used in known secondary batteries. The aforementioned waterproof structure maintains the electrical and mechanical properties of the secondary battery terminal.

[0010] This invention provides a secondary battery terminal that can maintain electrical and mechanical properties. and method for manufacturing terminals for secondary batteries The purpose is to provide. [Means for solving the problem]

[0011] One aspect of the present invention includes a first terminal material made of a first metal, a second terminal material made of a second metal different from the first metal, and a solid-state joint portion of the first metal and the second metal, wherein the solid-state joint portion joins the first terminal material and the second terminal material, the first terminal material includes a first portion on the first side in the first direction, the second terminal material includes a second portion on the second side in the first direction, the second portion covers and contacts the first portion, the first terminal material and the second terminal material form an interface between the first portion and the second portion in a covered state where the first portion is covered by the second portion, the interface includes an uneven region having an uneven shape in the first direction, the uneven region includes a first region and a second region that is connected to the first region on the outside of a radial second direction centered on a virtual axis along the first direction of the first region, the second region is on the first side in the first direction than the first region Having a height difference of the first dimension It has a convex shape and an annular shape surrounding the outer periphery of the first region, The first region has a shape in which the annular outer peripheral region, which includes the outer peripheral edge of the first region in the second direction and is connected to the second region, gradually slopes toward the first side in the first direction toward the outside in the second direction; the second region has a shape in which the annular inner peripheral region, which includes the inner peripheral edge of the second region on the central side in the second direction and is connected to the second region, gradually slopes toward the first side in the first direction toward the outside in the second direction; the outer peripheral region of the first region and the inner peripheral region of the second region form an inclined surface that gradually and continuously slopes toward the first side in the first direction toward the outside in the second direction; and the second dimension of the first region in the second direction is set to be larger than the first dimension. The solid-state bonding portion is the first region The central region on the central side in the second direction and the outer region of the first region are more central than the outer region of the first region. These are terminals for secondary batteries, provided in the [location].

[0012] The first metal may be copper, and the second metal may be aluminum.

[0013] Another aspect of the present invention is a method for manufacturing a secondary battery terminal as described above, comprising a forging step of forming the secondary battery terminal by compressing and deforming a first metal first member that forms the first terminal material and a second metal second member that forms the second terminal material at room temperature in the first direction while deforming them outward in the second direction, wherein the forging step forms the first member into the first terminal material, forms the second member into the second terminal material, and forms the room temperature pressure-welded portion as the solid-phase joint portion in the first region.

[0014] The above-mentioned terminals for secondary batteries and method for manufacturing terminals for secondary batteries According to this method, the outer periphery of the first region can be surrounded by the second region. By making the second region convex to the first side in the first direction compared to the first region, water that has penetrated from the outer edge can be prevented from reaching the first region at the interface. This can suppress the occurrence of electrolytic corrosion at the solid-state joint. [Effects of the Invention]

[0015] According to the present invention, a secondary battery terminal that can maintain electrical and mechanical properties. and method for manufacturing terminals for secondary batteries You can obtain this. [Brief explanation of the drawing]

[0016] [Figure 1] It is a perspective view showing an example of the schematic configuration of a terminal for a secondary battery. The state as seen from the first side in the first direction is shown. [Figure 2] It is a cross-sectional view of the terminal for a secondary battery in FIG. 1. The cutting position corresponds to the line I-I in FIG. 1. [Figure 3] It is a photograph showing an example of a normal temperature pressure contact part as a solid-phase joint part. The photographing range corresponds to the first region and the second region of the concavo-convex region of the interface in FIG. 2. [Figure 4] It is a cross-sectional view schematically showing an example of a manufacturing method of a terminal for a secondary battery. The state at the start (before start) of the forging process of the manufacturing method of the terminal for a secondary battery is shown. [Figure 5] It is a cross-sectional view schematically showing an example of a manufacturing method of a terminal for a secondary battery. The state during the implementation of the forging process of the manufacturing method of the terminal for a secondary battery is shown. [Figure 6] It is a cross-sectional view schematically showing an example of a manufacturing method of a terminal for a secondary battery. The state at the end of the forging process of the manufacturing method of the terminal for a secondary battery is shown.

Embodiments for Carrying Out the Invention

[0017] Embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the configurations described below, and various configurations can be adopted within the same technical idea. For example, some of the configurations shown below may be omitted or replaced with other configurations. The present invention may include other configurations. The drawings are explanatory diagrams for understanding the present invention and are different from design drawings. Each drawing may not be exactly corresponding to other drawings. Hatching indicates a cut surface. A one-dot chain line indicates a cutting position. A two-dot chain line indicates a virtual axis L. The virtual axis L will be described later.

[0018] <Terminal 10 for a secondary battery> The secondary battery terminal 10 will be described with reference to Figures 1 to 3. The secondary battery terminal 10 is provided on the secondary battery as a connection terminal for power supply. Examples of secondary batteries include vehicle batteries and residential storage batteries. An example of a vehicle is an automobile. Examples of automobiles include electric vehicles and internal combustion engine vehicles. The installation of the secondary battery terminal 10 on the secondary battery is the same as for known secondary battery terminals. Therefore, in this embodiment, a description related to this will be omitted.

[0019] In this embodiment, the secondary battery terminal 10 is defined by a first direction and a second direction. One side of the first direction is called the "first side," and the other side of the first direction is called the "second side." When the secondary battery terminal 10 is installed on the secondary battery, the first side of the first direction may be the upper side in the vertical direction. If the first side of the first direction is the upper side in the vertical direction, then the second side of the first direction will be the lower side in the vertical direction. The second direction is perpendicular to the first direction. The second direction is a radial direction centered on a virtual axis L. The second direction can also be described as a radial direction centered on a virtual axis L. The virtual axis L is along the first direction. In this embodiment, the virtual axis L coincides with the axis of the secondary battery terminal 10. In Figure 1, two directions that are perpendicular to each other are illustrated as the second direction.

[0020] The secondary battery terminal 10 includes a first terminal material 20, a second terminal material 40, and a solid-state joint 60 (see Figures 1 and 2). The first terminal material 20 is formed of a first metal. The second terminal material 40 is formed of a second metal. That is, in the secondary battery terminal 10, the first terminal material 20 is a first metal, and the second terminal material 40 is a second metal. The second metal is different from the first metal. An example of the first metal is copper. An example of the second metal is aluminum. In the secondary battery terminal 10, the first metal is copper, and the second metal is aluminum (see Figure 3). In such a combination, the second metal has lower hardness than the first metal. Copper includes copper alloys, and aluminum includes aluminum alloys. That is, the first metal may be a copper alloy, and the second metal may be an aluminum alloy.

[0021] The solid-state joint 60 is the joint between the first metal and the second metal. The solid-state joint 60 joins the first terminal material 20 and the second terminal material 40. An example of solid-state bonding that forms the solid-state joint 60 is room-temperature pressure welding. Room-temperature pressure welding is a type of solid-state bonding and is also called cold pressure welding. Room-temperature pressure welding joins the first metal and the second metal in a solid state at room temperature. The secondary battery terminal 10 includes a room-temperature pressure-welded portion as the solid-state joint 60. The room-temperature pressure-welded portion as the solid-state joint 60 is provided on the secondary battery terminal 10 by room-temperature pressure welding of the first metal and the second metal. This point will be described later.

[0022] The first terminal material 20 includes a first portion 30 on its first side in the first direction (see Figures 1 and 2). In other words, the first portion 30 forms the first side of the first terminal material 20 in the first direction. The first portion 30 includes a third portion 31 and a fourth portion 35 (see Figure 2). The third portion 31 forms the second side of the first portion 30 in the first direction. The fourth portion 35 forms the first side of the first portion 30 in the first direction. The fourth portion 35 is integrally formed with the third portion 31 on its first side in the first direction.

[0023] The second terminal material 40 includes a second portion 50 on the second side in the first direction (see Figures 1 and 2). In other words, the second portion 50 forms the second side of the second terminal material 40 in the first direction. The second portion 50 covers and contacts the first portion 30 (see Figure 2). In this embodiment, the state in which the first portion 30 is covered by the second portion 50 is referred to as the "covered state". In the covered state, the second portion 50 contacts the first end face of the first portion 30 in the first direction. The first end face of the first portion 30 in the first direction includes the first annular end face S1 and the first end face of the fourth portion 35 in the first direction. The first annular end face S1 will be described later. The first end face of the first portion 30 in the first direction becomes the first end face of the first terminal material 20 in the first direction. In the secondary battery terminal 10, the second portion 50 contacts the outer circumferential surface of the first portion 30 in the covered state. The outer circumferential surface of the first portion 30 includes the outer circumferential surface of the first annular portion 32 and the outer circumferential surface of the fourth portion 35. In the secondary battery terminal 10, the first terminal material 20 and the second terminal material 40 are crimped in the second direction by the covered first portion 30 and second portion 50.

[0024] The first terminal material 20 and the second terminal material 40 form an interface B between the first portion 30 and the second portion 50 in the covered state (see Figure 2). In the secondary battery terminal 10, the outer peripheral end C of interface B is exposed to the outside by the following end face. This end face includes the second side end face of the first portion 30 in the first direction and the second side end face of the second portion 50 in the first direction. Interface B includes an uneven region R0, and further includes an annular region R5 and a connecting region R6. The uneven region R0 has an uneven shape in the first direction. In the secondary battery terminal 10, the uneven region R0 is formed in the following range between the first portion 30 and the second portion 50 in the covered state. This range corresponds to the first side end face of the fourth portion 35 in the first direction.

[0025] The uneven region R0 includes the first region R1 and the second region R2 (see Figure 2). The second region R2 is connected to the first region R1 on the outside in the second direction of the first region R1. The second region R2 has a convex shape on the first side in the first direction of the first region R1 compared to the first region R1. In other words, the first region R1 has a concave shape on the second side in the first direction of the second region R2 compared to the second region R2. The second region R2 has an annular shape that surrounds the outer circumference of the first region R1. In the secondary battery terminal 10, the uneven region R0 includes the first region R1 and the second region R2, as well as the third region R3 and the fourth region R4. The third region R3 is connected to the second region R2 on the outside in the second direction of the second region R2. The fourth region R4 is connected to the third region R3 on the outside in the second direction of the third region R3. The second region R2 has a convex shape on the first side in the first direction of the third region R3 compared to the third region R3. The fourth region R4 has a convex shape on the first side in the first direction compared to the third region R3. In other words, the third region R3 has a concave shape on the second side in the first direction compared to the second region R2 and the fourth region R4. The third region R3 has an annular shape. The fourth region R4 has an annular shape. The fourth region R4 forms the outer edge of the convex-convex region R0.

[0026] In this embodiment, with respect to interface B, two symbols "R2" indicating the second region, two symbols "R3" indicating the third region, two symbols "R4" indicating the fourth region, two symbols "R5" indicating the annular region, two symbols "R6" indicating the connecting region, and two symbols "C" indicating the outer edge are attached to both sides of the first region R1 in the second direction (see Figure 2 and Figure 6 described later). However, the second region with two symbols "R2" has an integral annular shape. The third region with two symbols "R3" has an integral annular shape. The fourth region with two symbols "R4" has an integral annular shape. The annular region with two symbols "R5" has an integral annular shape. The connecting region with two symbols "R6" has an integral annular shape. The outer edge with two symbols "C" has an integral annular shape.

[0027] In the secondary battery terminal 10, the first region R1 is surrounded by the second region R2, which has the second region R2 as its outer circumferential wall, and the third region R3 is surrounded by the second region R2 and the fourth region R4, which has the second region R2 as its inner circumferential wall and the fourth region R4 as its outer circumferential wall (see Figure 2). The fourth region R4 has a convex shape on the first side in the first direction compared to the first region R1. Therefore, in the secondary battery terminal 10, the fourth region R4 can also be defined as having an annular shape that surrounds the outer periphery of the first region R1 via the second region R2 and the third region R3. In the secondary battery terminal 10, the solid-phase joint 60 is provided in the first region R1 (see Figures 2 and 3). The area in which the solid-phase joint 60 is provided includes the center of the first region R1. The area in which the solid-phase joint 60 is provided may be a part of the first region R1 or all of it.

[0028] In the first terminal material 20, the third portion 31 includes the first annular portion 32 (see Figure 2). The first annular portion 32 protrudes outward in the second direction from the fourth portion 35. The first annular portion 32 has a first annular end face S1 on the first side in the first direction. The first annular end face S1 is the end face of the first annular portion 32 on the first side in the first direction. As described above, the first annular end face S1 is part of the end face of the first portion 30 on the first side in the first direction. On the first annular end face S1, the position in the first direction is the first side in the first direction, moving outward from the center side in the second direction. That is, the first annular end face S1 is inclined on the first side in the first direction, moving outward from the center side in the second direction. In the second terminal material 40, the second portion 50 includes the second annular portion 51. The second annular portion 51 is in contact with the first annular portion 32 in a covered state. The second annular portion 51 has a second annular end face S2. The second annular end face S2 is in contact with the first annular end face S1 in the covered state. The first annular end face S1 and the second annular end face S2 form an annular region R5.

[0029] The connection region R6 connects the inner peripheral edge of the annular region R5 on the second direction's center side and the outer peripheral edge of the uneven region R0 on the second direction's outer side (see Figure 2). The uneven region R0 is located on the first side in the first direction relative to the inner peripheral edge of the annular region R5. At the secondary battery terminal 10, the dimension DB in the second direction of the outer peripheral edge of the uneven region R0 is set to be larger than the dimension DA in the second direction of the inner peripheral edge of the annular region R5. The connection region R6 has the following shape. This shape slopes outward from the center side in the second direction, moving from the second side in the first direction towards the first side.

[0030] <Manufacturing method for secondary battery terminals 10> A method for manufacturing the secondary battery terminal 10 will be described with reference to Figures 4 to 6. The secondary battery terminal 10 is manufactured using a first member 25 and a second member 45 as materials. The first member 25 is made of first metal and is the material for the first terminal material 20. The second member 45 is made of second metal and is the material for the second terminal material 40. The manufacturing method for the secondary battery terminal 10 is carried out by a press device. A mold 70 is attached to the press device. In this embodiment, the illustration of the press device is omitted. The mold 70 includes a first mold 71 and a second mold 74 and is formed by a pair of first molds 71 ​​and second molds 74. The first mold 71 and the second mold 74 are attached to the press device facing each other in the first direction. The first mold 71 is provided on the second side of the first direction with the first mold 71 and second mold 74 facing each other in the first direction. The second mold 74 is provided on the first side of the first direction with the first mold 71 and second mold 74 facing each other in the first direction. In other words, the first type 71 is provided on the second side of the first direction of the second type 74. To put it another way, the second type 74 is provided on the first side of the first direction of the first type 71.

[0031] The first mold 71 includes a first body 72 and a first pin 73. The first pin 73 moves in a first direction relative to the first body 72. The second mold 74 includes a second body 75 and a second pin 76. The second pin 76 moves in a first direction relative to the second body 75. In the mold 70, the diameter φ1 of the first pin 73 and the diameter φ2 of the second pin 76 are set to "φ1 > φ2" (see Figures 4 and 5). A space with the following shape is formed inside the mold 70. This shape corresponds to the outer shape of the secondary battery terminal 10 (see Figure 6). This space is also called a cavity.

[0032] The manufacturing method for the secondary battery terminal 10 includes a pre-processing step, a forging step, and an extraction step, which are performed in this order. The pre-processing step involves cleaning the surface of the first member 25 and the surface of the second member 45. In the manufacturing method for the secondary battery terminal 10, the following known treatment can be used as the pre-processing step. This known treatment is performed before the known room-temperature pressure welding and cleans the surface of the parts to be joined by room-temperature pressure welding. Therefore, further explanation regarding the pre-processing step is omitted. After the completion of the pre-processing step, the manufacturing method for the secondary battery terminal 10 proceeds to the forging step.

[0033] The forging process is carried out on the first member 25 and the second member 45, whose surfaces have been cleaned by the preceding process. The forging process forges the first member 25 and the second member 45 in a mold 70. In the method for manufacturing the secondary battery terminal 10, the forging process includes the following procedure. This procedure involves pressing the first member 25 and the second member 45 firmly together at room temperature. The forging process presses the first member 25 and the second member 45 firmly together at room temperature, thereby pressing the first metal and the second metal together at room temperature. The forging process forms the first terminal material 20 from the first member 25 and the second terminal material 40 from the second member 45, while forming an interface B between the first part 30 and the second part 50. Furthermore, the forging process forms a solid-state joint 60 in the first region R1 of the uneven region R0 of interface B.

[0034] Before the start of the forging process, the first member 25 and the second member 45 are housed in the die 70 (see Figure 4). The first member 25 and the second member 45 overlap in contact in the first direction within the die 70. The shapes of the first member 25 and the second member 45 shown in Figure 4 are illustrative examples. The shapes of the first member 25 and the second member 45 are determined appropriately considering various conditions. During the forging process, one or both of the first die 71 and the second die 74 move in the first direction, and the first die 71 and the second die 74 approach each other in the first direction (see Figures 4 and 5). Assume that the first die 71 moves in the first direction during the forging process. In this case, the first die 71 moves from the second side to the first side in the first direction. Assume that the second die 74 moves in the first direction during the forging process. In this case, the second die 74 moves from the first side to the second side in the first direction. Stress acts on the first member 25 and the second member 45 in the first direction as the first die 71 and the second die 74 approach each other in the first direction. The first member 25 and the second member 45 undergo compressive deformation in the first direction. While undergoing compressive deformation in the first direction, the first member 25 and the second member 45 also deform outward in the second direction. The first member 25 and the second member 45 form an interface in the area where they contact each other. In this embodiment, the area where the first member 25 and the second member 45 contact each other is called the "contact area". The deformation that occurs in the first member 25 and the deformation that occurs in the second member 45 is plastic deformation.

[0035] In the mold 70, after the start of the forging process, the first mold 71 and the second mold 74 approach each other in the first direction, causing the first body 72 and the second body 75 to come into contact (see Figure 5). In the mold 70, the following operation is initiated in response to the contact between the first body 72 and the second body 75. In this operation, the first pin 73 moves to the first side in the first direction, and the second pin 76 moves to the second side in the first direction. The first pin 73 locally pushes the central portion of the first member 25 to the first side in the first direction, and the second pin 76 locally pushes the central portion of the second member 45 to the second side in the first direction. Stress continues to act on the first member 25 and the second member 45 in the first direction even after the contact between the first body 72 and the second body 75. By making the diameter φ2 of the second pin 76 smaller than the diameter φ1 of the first pin 73, the second forming pressure can be made higher than the first forming pressure. The first forming pressure acts on the central portion of the first member 25 in conjunction with the pushing by the first pin 73. The second molding pressure acts on the central portion of the second member 45 as it is pressed by the second pin 76.

[0036] The central portions of the first member 25 and the second member 45 are compressed and deformed in the first direction. The first member 25 and the second member 45 each deform outward in the second direction while being compressed and deformed in the first direction at their central portions. The first member 25 and the second member 45 deform the already formed interface, expanding it to a newly formed contact area. The interface formed between the first member 25 and the second member 45 deforms into a shape including the uneven region R0, becoming interface B. The central portions of the first member 25 and the second member 45 are strongly pressed in the first direction while being sandwiched in the first direction by the first pin 73 and the second pin 76. Between the central portions of the first member 25 and the second member 45, the first metal and the second metal are pressure-welded at room temperature, and a solid-state joint 60 is provided in the first region R1 of the uneven region R0 of interface B. In the forging process, the solid-state joint 60 is formed as a room-temperature pressure-welded portion of the first metal and the second metal.

[0037] The forging process ends at the following timing. At this timing, the first pin 73 reaches the first moving end in the first direction, and the second pin 76 reaches the second moving end in the first direction. After the forging process is completed, the manufacturing method of the secondary battery terminal 10 moves to the removal process. In the removal process, the secondary battery terminal 10 is removed from the mold 70. In the removal process, the first and second steps are performed. The first step separates the first mold 71 and the second mold 74 in the first direction. The first step may also move the first pin 73 to the second side in the first direction. The first step may also move the second pin 76 to the first side in the first direction. The second step removes the secondary battery terminal 10 from the mold 70 with the first mold 71 and the second mold 74 separated in the first direction. The manufacturing method of the secondary battery terminal 10 ends with the completion of the removal process.

[0038] <Effects of the Embodiment> According to this embodiment, the following effects can be obtained.

[0039] (1) The secondary battery terminal 10 includes a first terminal material 20, a second terminal material 40, and a solid-state joint 60 (see Figures 1 and 2). The first terminal material 20 is made of a first metal. The second terminal material 40 is made of a second metal. The second metal is different from the first metal. The solid-state joint 60 is the joint between the first metal and the second metal, and joins the first terminal material 20 and the second terminal material 40 (see Figures 2 and 3). The first terminal material 20 includes a first portion 30 on the first side in the first direction (see Figures 1 and 2). The second terminal material 40 includes a second portion 50 on the second side in the first direction (see Figure 2). The second portion 50 covers the first portion 30 and is in contact with the first portion 30. In the covered state, the first terminal material 20 and the second terminal material 40 form an interface B between the first portion 30 and the second portion 50. In the covered state, the first portion 30 is covered by the second portion 50. Interface B includes an uneven region R0. The uneven region R0 has an uneven shape in the first direction. The uneven region R0 includes the first region R1 and the second region R2. The second region R2 is connected to the first region R1 on the outside of the first region R1 in the second direction. The second direction is a radial direction centered on a virtual axis L along the first direction. The second region R2 has a convex shape on the first side of the first direction compared to the first region R1, and an annular shape surrounding the outer circumference of the first region R1. The solid-state joint 60 is provided in the first region R1.

[0040] In the secondary battery terminal 10, the solid-state joint 60 is a room-temperature pressure-welded joint of a first metal and a second metal (see Figure 3). In the secondary battery terminal 10, the first metal is copper and the second metal is aluminum.

[0041] With the secondary battery terminal 10, the outer periphery of the first region R1 can be surrounded by the second region R2. By making the second region R2 convex to the first side in the first direction compared to the first region R1, water that has penetrated from the outer edge C at interface B can be prevented from reaching the first region R1. The occurrence of electrolytic corrosion at the solid-phase joint 60 can be suppressed. The secondary battery terminal 10 can maintain its electrical and mechanical properties.

[0042] (2) Interface B includes an uneven region R0, an annular region R5, and a connecting region R6 (see Figure 2). In the first terminal material 20, the third portion 31 includes the first annular portion 32. The first annular portion 32 protrudes outward in the second direction from the fourth portion 35. The first annular portion 32 has a first annular end face S1 on the first side in the first direction. On the first annular end face S1, the position in the first direction is the first side in the first direction, moving outward from the center side in the second direction. In the second terminal material 40, the second portion 50 includes the second annular portion 51. The second annular portion 51 is in contact with the first annular portion 32 in the covered state. The second annular portion 51 has a second annular end face S2. The second annular end face S2 is in contact with the first annular end face S1 in the covered state. The first annular end face S1 and the second annular end face S2 form the annular region R5. The connecting region R6 connects the inner peripheral edge of the annular region R5 on the second direction side to the outer peripheral edge of the uneven region R0 on the second direction side. The uneven region R0 is located on the first side in the first direction relative to the inner peripheral edge of the annular region R5.

[0043] This configuration allows for a longer path length from the outer edge C to the uneven region R0 at interface B. At interface B, it is possible to prevent water that has penetrated from the outer edge C to interface B from reaching the uneven region R0. The occurrence of electrolytic corrosion at the solid-phase joint 60 can be suppressed. The electrical and mechanical properties of the secondary battery terminal 10 can be maintained.

[0044] <Variation> The embodiment can also be as follows. Some of the modifications shown below can be combined and adopted as appropriate. Below, we will explain the differences from the above, and explain the similarities as appropriate.

[0045] (1) The solid-state joint 60 is provided in the first region R1 (see Figures 2 and 3). The area in which the solid-state joint 60 is provided includes the center of the first region R1. The area in which the solid-state joint 60 is provided may be a part of the first region R1 or all of it. The solid-state joint 60 may be extended to the second region R2, or to the third region R3, or even to the fourth region R4. The area in which the solid-state joint 60 is provided is determined appropriately considering various conditions. However, as mentioned above, the area in which the solid-state joint 60 is provided includes the center of the first region R1.

[0046] (2) The uneven region R0 includes the first region R1, the second region R2, the third region R3, and the fourth region R4 (see Figure 2). The second region R2 has a convex shape on the first side in the first direction compared to the first region R1, and an annular shape surrounding the outer circumference of the first region R1. In the uneven region, the fourth region R4 may be omitted, or the third region R3 and the fourth region R4 may be omitted. The uneven region only needs to have a configuration in which the outer circumference of the first region is surrounded by the second region having the shape described above. However, in the secondary battery terminal 10, the second region R2 increases the path length from the outer edge of the uneven region R0 to the first region R1 at interface B, and the third region R3 or the third region R3 and the fourth region R4 can further increase this path length (see Figure 2). At interface B, it is possible to prevent water that has penetrated from the outer edge C to interface B from reaching the first region R1. [Explanation of Symbols]

[0047] 10 Terminal for secondary battery, 20 First terminal material, 25 First component, 30 First part 31 third part, 32 first annular part, 35 fourth part, 40 second terminal material 45 Second member, 50 Second part, 51 Second annular part, 60 Solid phase joint 70 Mold, 71 First type, 72 First body, 73 First pin, 74 Second type 75 Second body, 76 Second pin, B Interface, C Outer perimeter, DA, DB Indentation method, L Imaginary axis, R0 Concave / convex region, R1 First region, R2 Second region R3 Third Domain, R4 Fourth Domain, R5 Circular Domain, R6 Connecting Domain S1 First annular end face, S2 Second annular end face, φ1, φ2 Diameter

Claims

1. First terminal material manufactured by First Metal Co., Ltd., A second terminal material made of a second metal different from the first metal, The solid-state joint portion of the first metal and the second metal, The solid-phase joint joins the first terminal material and the second terminal material, The first terminal material includes a first portion on the first side in the first direction, The second terminal material includes a second portion on the second side in the first direction. The aforementioned second part is, Covering the first portion, and In contact with the aforementioned first part, The first terminal material and the second terminal material form an interface between the first and second parts in a covered state in which the first part is covered by the second part. The interface includes an uneven region having an uneven shape in the first direction, The aforementioned uneven region is The first domain and The first region includes a second region that is adjacent to the first region and is located outside the second radial direction centered on a virtual axis along the first direction of the first region, The second region has a convex shape having a height difference of a first dimension on the first side in the first direction compared to the first region, and an annular shape surrounding the outer circumference of the first region. The first region has a shape in which the annular outer region, which includes the outer peripheral edge of the first region in the second direction and is connected to the second region, gradually inclined toward the first side in the first direction toward the outside in the second direction, The second region includes the inner peripheral edge of the second region on the central side in the second direction, and the annular inner peripheral region extending from the outer peripheral edge of the first region to the convex apex of the second region has a shape that gradually slopes outward in the second direction toward the first side in the first direction. The outer peripheral region of the first region and the inner peripheral region of the second region form inclined surfaces that gradually and continuously slope outward in the second direction toward the first side in the first direction. The second dimension of the first region in the second direction is set to be larger than the first dimension. The solid-phase bonding portion is a terminal for a secondary battery, provided in the central region on the second direction side of the outer peripheral region of the first region and in the outer peripheral region of the first region.

2. The first metal is copper, The secondary battery terminal according to claim 1, wherein the second metal is aluminum.

3. A method for manufacturing a secondary battery terminal according to Claim 1 or Claim 2, The process includes a forging step in which the first metal first member that forms the first terminal material and the second metal second member that forms the second terminal material are compressed and deformed in the first direction while being deformed outward in the second direction at room temperature to form the terminal for the secondary battery, wherein the first metal first member that forms the first terminal material and the second metal second member that forms the second terminal material are compressed and deformed in the first direction while being deformed outward in the second direction, respectively. The aforementioned forging process is The first member is formed into the first terminal material, The second member is formed into the second terminal material, A method for manufacturing a secondary battery terminal, comprising forming a room-temperature pressure-welded portion as a solid-phase bonding portion in the first region.

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