JP2024085618A - Battery terminal, secondary battery, and method of manufacturing battery terminal - Google Patents

Abstract

A battery terminal is provided that can ensure a larger busbar welding area in the terminal than before and can suppress the generation of foreign matter inside the secondary battery due to ultrasonic welding.
[Solution] A battery terminal 26 consisting of a first member 40 and a second member 50 made of metal, the first member 40 is a plate-shaped member whose surface is a busbar welding surface, and has an accommodating recess 42 that opens on the back surface and has a first horn side bonding surface 44 that is an inner surface parallel to the thickness direction, the second member 50 has a first anvil side bonding surface 53 on its outer surface, and at least a portion of it is accommodated in the accommodating recess 42 so that the first anvil side bonding surface 53 faces the first horn side bonding surface 44, and the first horn side bonding surface 44 and the first anvil side bonding surface 53 are joined by ultrasonic welding.
[Selected Figure] Figure 6

Description

The present invention relates to a battery terminal, a secondary battery, and a method for manufacturing a battery terminal.

Traditionally, electric vehicles, hybrid vehicles, and other electric vehicles that use motors as their drive source use secondary batteries such as nickel-metal hydride batteries and lithium-ion batteries as their power source. To achieve the performance required of a drive source for an electric vehicle, these types of secondary batteries are usually used as the power source for the electric vehicle in the form of a battery module in which multiple batteries are electrically connected together to increase the charge/discharge capacity and output voltage.

When multiple secondary batteries are electrically connected, the positive and negative terminals of one secondary battery are generally electrically connected to the negative and positive terminals of an adjacent secondary battery via bus bars welded to the top surface of each terminal.

When adopting a structure in which a bus bar is welded to the top surface of each terminal (bus bar welded structure), it is desirable that the metal constituting the top surface of each terminal is the same, taking into consideration the weldability of the bus bar. Therefore, if the metal constituting the current collecting terminal joined to the electrode body is different between the positive terminal and the negative terminal, dissimilar material joining may be required on the positive or negative side to make the metal constituting the top surface of each terminal the same. For example, if the current collecting terminal on the positive electrode side is aluminum and the current collecting terminal on the negative electrode side is copper, dissimilar material joining of aluminum and copper is required on the negative electrode side to make the top surface of the terminal out of aluminum.

As a result, a technique for joining two dissimilar materials to make the metal that constitutes the top surface of each terminal the same has been proposed, such as the secondary battery terminal described in Patent Document 1.

The secondary battery terminal described in Patent Document 1 is composed of a plate-shaped metal first member and a second member ultrasonically welded to the back surface of the plate of the first member, with the first member being disposed on the exterior side of the secondary battery and the second member on the interior side. In this secondary battery terminal, a recess is formed on the surface of the first member, and a crimping portion is formed on the side of the second member opposite to the side to which the first member is welded, and ultrasonic welding between the first member and the second member is achieved by the recess of the first member and the crimping portion of the second member.

With this secondary battery terminal, a recess is formed in the first member, and ultrasonic welding is achieved using this recess, eliminating the need to remove any irregularities or burrs that may occur on the metal surface that is pressed together for ultrasonic welding before welding the bus bar.

JP 2022-49726 A

However, in the secondary battery terminal described in Patent Document 1, a recess needs to be formed on the surface of the first member, which reduces the area of the portion to which the bus bar can be welded (bus bar weldable area). This makes it difficult to reduce the size of the secondary battery and therefore makes it difficult to reduce the manufacturing costs of the secondary battery.

In addition, welding marks such as unevenness and burrs may appear on the crimped portion of the second member, which may cause foreign matter from the second member to be generated inside the secondary battery, resulting in a problem of reduced performance of the secondary battery.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a battery terminal, a secondary battery, and a method for manufacturing a secondary battery that can ensure a larger busbar welding area in the terminal than before and can suppress the generation of foreign matter inside the secondary battery due to ultrasonic welding.

The characteristic configuration of the battery terminal according to the present invention for achieving the above object is as follows:
A battery terminal comprising a first member and a second member made of metal,
The first member is
A plate-shaped member having a bus bar welding surface on one surface,
An accommodating recess is formed on the rear surface thereof and has a first horn side bonding surface which is an inner surface parallel to the thickness direction thereof,
The second member is
A first anvil-side joint surface is provided on the outer surface.
At least a portion of the first anvil-side bonding surface is accommodated in the accommodation recess so as to face the first horn-side bonding surface,
The first horn side joining surface and the first anvil side joining surface are joined by ultrasonic welding.

According to the above characteristic configuration, the weld marks caused by ultrasonic welding between the first horn side joint surface and the first anvil side joint surface are generated on the outer surface of the accommodating recess, and are not generated on the surface of the first member, which is the busbar welding surface, or on the portion that will be located inside the secondary battery (e.g., the crimped portion in the conventional technology). Therefore, a wide busbar welding area can be secured, and when the battery terminal is used in a secondary battery, the generation of foreign matter inside the secondary battery due to ultrasonic welding can be suppressed.

Further, a further characteristic configuration of the battery terminal according to the present invention is as follows:
The first member is
The plate has a pair of side surfaces that are parallel to the thickness direction and parallel to each other,
The feature is that an area of the pair of side surfaces, which corresponds to the first horn side bonding surface at least in the thickness direction, is a notch portion in which the distance between the side surfaces is shorter than that on the front surface side.

According to the above characteristic configuration, the weld marks caused by ultrasonic welding occur in the notch portion where the distance between the side surfaces is shorter than the surface side, so when viewed in a direction perpendicular to the surface of the first member, the weld marks are unlikely to protrude from the surface edge of the first member. Therefore, when the battery terminal is attached to the lid body to be used as a terminal for a secondary battery, it is easy to suppress adverse effects (such as reduced insulation) caused by the weld marks coming into contact with members such as a gasket that insulates the battery terminal from the lid body.

Further, a further characteristic configuration of the battery terminal according to the present invention is as follows:
the accommodating recess has a second horn-side bonding surface that is an inner surface parallel to the thickness direction and facing the first horn-side bonding surface with the second member therebetween,
the second member has a second anvil-side joint surface that is an outer surface facing the second horn-side joint surface,
The second horn side joining surface and the second anvil side joining surface are joined by ultrasonic welding.

According to the above characteristic configuration, the first member and the second member are joined at at least two locations, namely, the joining location between the first horn side joining surface and the first anvil side joining surface, and the joining location between the second horn side joining surface and the second anvil side joining surface, thereby improving the joining strength between the first member and the second member.

Further, a further characteristic configuration of the battery terminal according to the present invention is as follows:
The first member is made of aluminum,
The second member is made of copper.

According to the above characteristic configuration, when the metal constituting the negative electrode collector terminal joined to the negative electrode of the electrode body is copper, the negative electrode collector terminal can be joined to the second member in an appropriate manner, and an appropriate negative electrode terminal in which the busbar welding surface is made of aluminum can be realized.

The secondary battery according to the present invention, which achieves the above object, has the following characteristic configuration:
A housing having an opening;
a cover for sealing an opening of the housing;
A current collecting terminal disposed inside the housing;
a battery terminal electrically connected to the current collecting terminal;
The battery terminal is
The first member and the second member are made of metal.
The first member is
A plate-shaped member having a bus bar welding surface on one surface,
An accommodating recess is formed on the rear surface thereof and has a first horn side bonding surface which is an inner surface parallel to the thickness direction thereof,
The second member is
A first anvil-side joint surface is provided on the outer surface.
At least a portion of the first anvil-side bonding surface is accommodated in the accommodation recess so as to face the first horn-side bonding surface,
the first horn side joining surface and the first anvil side joining surface are joined by ultrasonic welding,
The surface of the first member is located outside the lid, and the second member is electrically connected to the current collecting terminal inside the housing.

According to the above characteristic configuration, the weld marks caused by ultrasonic welding between the first horn side joint surface and the first anvil side joint surface are generated on the outer surface of the accommodating recess in the first member, and are not generated on the surface of the first member as the busbar welding surface located on the outside of the lid body, or on the second member connected to the current collecting terminal inside the housing. Therefore, a wide busbar welding area can be secured, and the generation of foreign matter inside the secondary battery due to ultrasonic welding can be suppressed.

The characteristic configuration of the manufacturing method of the battery terminal according to the present invention for achieving the above object is as follows:
A method for manufacturing a battery terminal by joining a first member, which is a metal plate-like member and has an accommodating recess formed therein, the first member having an opening on a rear surface and a first horn-side bonding surface that is an inner surface parallel to a thickness direction, to a second metal member having a first anvil-side bonding surface on an outer surface thereof,
an accommodating step of accommodating at least a portion of the second member in an accommodating recess of the first member such that the first anvil-side bonding surface faces the first horn-side bonding surface;
a first direction being a direction perpendicular to the first horn side bonding surface and the first anvil side bonding surface, and with a first member fixed with an anvil on the side of the first anvil side bonding surface in the first direction, a horn is pressed against the outer surface of the first member along the first direction from the side of the first horn side bonding surface in the first direction to apply ultrasonic vibrations in a direction parallel to the first horn side bonding surface and the first anvil side bonding surface, thereby bonding the first horn side bonding surface and the first anvil side bonding surface.

The above characteristic configuration makes it possible to suitably manufacture a battery terminal in which contact marks resulting from ultrasonic welding between the first horn side joining surface and the first anvil side joining surface are generated on the outer surface of the housing recess, and are not generated on the surface of the first member, which is the busbar welding surface, or on the portion that will be located inside the secondary battery (e.g., the crimped portion of the conventional technology). Furthermore, with a battery terminal manufactured by this manufacturing method, a wide busbar welding area can be secured, and when the battery terminal is used in a secondary battery, the generation of foreign matter inside the secondary battery due to ultrasonic welding can be suppressed.

As described above, the battery terminal, secondary battery, and method of manufacturing the battery terminal according to the present invention can ensure a larger busbar welding area in the terminal than in the past, and can suppress the generation of foreign matter inside the secondary battery due to ultrasonic welding.

1 is an exploded perspective view of a secondary battery according to an embodiment; 1 is a cross-sectional view showing a schematic configuration of a secondary battery according to an embodiment. 3 is an enlarged cross-sectional view showing part N (the periphery of a negative electrode terminal) in FIG. 2. 4A and 4B are a cross-sectional view and a bottom view showing a first member. 4A and 4B are a cross-sectional view and a bottom view showing a second member. 4A to 4C are cross-sectional views illustrating a method of ultrasonically welding a first member and a second member together. 1A to 1C are top views each showing a schematic diagram of a method for ultrasonically welding a first member and a second member together.

Below, a battery terminal, a secondary battery, and a method for manufacturing a battery terminal according to one embodiment of the present invention will be described with reference to the drawings. Note that, below, an example will be described in which the secondary battery is a lithium-ion secondary battery. Also, below, each description and each drawing will be appropriately simplified to clarify the explanation.

[Outline of secondary battery 1]
An outline of a secondary battery 1 according to the present embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is an exploded perspective view of the secondary battery 1 according to the present embodiment. Fig. 2 is a cross-sectional view showing a schematic configuration of the secondary battery 1 according to the present embodiment.

As shown in Figs. 1 and 2, the secondary battery 1 of this embodiment includes a battery case 10 consisting of a case body 11 and a sealing plate 12, external terminals 25, 26, and current collector terminals 27, 28. In this embodiment, the secondary battery 1 also includes an electrode body 20 and an electrolyte (not shown). The secondary battery 1 is a sealed secondary battery in which the electrode body 20 and current collector terminals 27, 28 are housed inside the case body 11, the opening is sealed with the sealing plate 12, and the electrolyte is injected into the inside of the case body 11. In this embodiment, the case body 11 corresponds to the "housing" and the sealing plate 12 corresponds to the "lid".

[Configuration of battery case 10]
1 and 2, the battery case 10 is composed of a case body 11 that is open at the top, and a sealing plate 12 that seals the opening of the case body 11. In this embodiment, both the case body 11 and the sealing plate 12 are made of aluminum, but the material is not limited to this.

In this embodiment, the case body 11 has a generally rectangular parallelepiped shape. The case body 11 has a pair of side walls 11a arranged opposite each other along the longitudinal direction, a pair of end side walls 11b connecting the longitudinal ends of the side walls 11a, and a bottom portion 11c that closes the bottom.

The sealing plate 12 has a shape corresponding to the shape of the opening of the case body 11. The sealing plate 12 of this embodiment is made of a flat plate member having a generally rectangular shape when viewed from above. The sealing plate 12 has a positive electrode terminal arranged at one end in the longitudinal direction and a negative electrode terminal arranged at the other end in the longitudinal direction, and a through hole 12a through which each external terminal 25, 26 described later is inserted is formed through the top and bottom surfaces (front and back surfaces). In addition, the sealing plate 12 has a safety valve 13 formed near the center in the longitudinal direction, which opens to release the internal pressure when the internal pressure of the battery case 10 becomes equal to or higher than a threshold value, and a liquid injection part 14 for injecting electrolyte into the inside of the battery case 10 is formed between the negative electrode terminal and the safety valve 13.

[Configuration of electrode body 20]
The electrode body 20 is composed of a positive electrode, a negative electrode, and a separator. As shown in FIG. 1 and FIG. 2, the electrode body 20 of the present embodiment is composed of a wound body in which long strip-shaped positive and negative electrode materials are stacked with a strip-shaped separator interposed therebetween, wound, and compressed into a flat shape. Specifically, the electrode body 20 of the present embodiment is substantially rectangular when viewed in the thickness direction. In addition, in the present embodiment, a positive electrode terminal joint 21 in which the positive electrode material is collected is formed at one end side in the winding axis direction (longitudinal direction of the electrode body 20), and a negative electrode terminal joint 22 in which the negative electrode material is collected is formed at the other end side. The structure of the electrode body 20 is not particularly limited, and various structures used in general sealed secondary batteries can be adopted. As an example, the electrode body 20 may be composed of a flat-shaped laminate in which the positive electrode material and the negative electrode material are stacked with a separator interposed therebetween. The materials used for the positive and negative electrodes are not particularly limited, but in this embodiment, aluminum is used for the positive electrode material and copper is used for the negative electrode material.

In this embodiment, the electrode body 20 is housed inside the case body 11 in a position where the thickness direction and the winding axis direction (longitudinal direction) are parallel to the horizontal direction, and both sides in the thickness direction face the side walls 11a of the case body 11. Although not shown in the figure, the electrode body 20 is housed inside the case body 11 in a bag made of an insulating film, and is insulated from the case body 11 by the bag.

[Positive and negative electrode configurations]
In this embodiment, the secondary battery 1 includes a positive external terminal 25 and a negative external terminal 26 as external terminals, and includes a positive current collector terminal 27 and a negative current collector terminal 28 as current collector terminals. In this embodiment, the positive terminal is composed of the positive external terminal 25 and the positive current collector terminal 27, and the negative terminal is composed of the negative external terminal 26 and the negative current collector terminal 28. The secondary battery 1 of this embodiment also includes a positive insulating member 29, a negative insulating member 30, a positive gasket 31, and a negative gasket 32. In this embodiment, the negative external terminal 26 corresponds to the "battery terminal".

In this embodiment, the positive and negative electrodes have substantially the same configuration, but the structure and material of the external terminals and the material of the current collecting terminals are different. Below, the configuration of the negative electrode side will be described with reference to Figures 3 to 5. Figure 3 is an enlarged cross-sectional view showing part N (negative electrode terminal periphery) in Figure 2, Figure 4 is a cross-sectional view and bottom view showing the first member 40, and Figure 5 is a cross-sectional view and bottom view showing the second member 50.

The negative electrode external terminal 26 is a terminal for external connection, and is made of a first member 40 and a second member 50 made of metal. Specifically, the negative electrode external terminal 26 in this embodiment is a dissimilar material joint member in which the first member 40 made of aluminum and the second member 50 made of copper are joined by ultrasonic welding.

As shown in FIG. 4, the first member 40 of this embodiment is a plate-like member having a generally rectangular shape when viewed from above, and the surface 41a (upper surface) is a busbar welding surface. The first member 40 has a housing recess 42 formed on its back surface 41b (lower surface) so as to open to the back surface 41b in a generally rectangular shape when viewed from below. In this embodiment, the housing recess 42 has an inner surface 43 parallel to the thickness direction of the first member 40. The inner surface 43 has a pair of surfaces 43a parallel to the short side direction and a pair of surfaces 43b parallel to the long side direction. The two surfaces 43a of the inner surface 43 of the housing recess 42 that face each other and are parallel to the short side direction constitute a first horn side joint surface 44 and a second horn side joint surface 45. That is, the housing recess 42 of the first member 40 has a first horn side joining surface 44, which is an inner surface 43 parallel to the thickness direction, and a second horn side joining surface 45, which is an inner surface 43 parallel to the thickness direction and facing the first horn side joining surface 44.

In addition, the first member 40 of this embodiment has an outer peripheral surface 46 parallel to the thickness direction. The outer peripheral surface 46 has a pair of faces 46a parallel to the short side direction and a pair of faces 46b parallel to the long side direction. Then, on the back surface 41b side of the outer peripheral surface 46, a notch portion 47 is formed over the entire circumferential direction so that the outer peripheral surface 46 is recessed toward the storage recess 42 side more than the front surface 41a side. The notch portion 47 has a notch surface parallel to the thickness direction, and the notch surface has two notch surfaces 47a, 47b parallel to the short side direction. The notch portion 47 is formed in an area corresponding to the first horn side joint surface 44 and the second horn side joint surface 45 in the thickness direction of the first member 40. In this embodiment, the pair of faces 46a parallel to the short side direction of the outer peripheral surface 46 corresponds to the "pair of side surfaces". That is, the first member 40 has a pair of side surfaces, at least in the thickness direction, in an area corresponding to the first horn side joint surface 44, with a cutout portion 47 in which the distance between the side surfaces is shorter than the front surface 41a. In addition, the first member 40 of this embodiment has the housing recess 42 and the cutout portion 47 formed therein, so that it has a first frame portion 48 that is generally rectangular in bottom view and extends downward from the back surface 41b.

As shown in FIG. 5, the second member 50 of this embodiment has a plate-shaped portion 51 that is generally rectangular when viewed from above, and a shaft portion 55 that extends downward from the center of the back surface 51b of the plate-shaped portion 51.

The plate-like portion 51 of the second member 50 has an outer peripheral surface 52 parallel to the thickness direction. The outer peripheral surface 52 has a pair of surfaces 52a parallel to the short side direction and a pair of surfaces 52b parallel to the long side direction, and in this embodiment, one of the pair of surfaces 52a parallel to the short side direction is the first anvil side joint surface 53, and the other is the second anvil side joint surface 54. The shaft portion 55 of the second member 50 has a crimping portion 56 formed on its lower end side.

Although the details will be described later, the negative electrode external terminal 26 of this embodiment is a member that is manufactured by pressing a joining tool (horn and anvil) against the outer surface (specifically, the notched surfaces 47a, 47b) of the accommodation recess 42 of the first member 40 while the plate-shaped portion 51 of the second member 50 is accommodated in the accommodation recess 42 of the first member 40, and joining the first horn side joining surface 44 and the first anvil side joining surface 53, and the second horn side joining surface 45 and the second anvil side joining surface 54 by ultrasonic welding. Therefore, the welding marks caused by ultrasonic welding are generated on the outer surface (notched surfaces 47a, 47b) of the accommodation recess 42. Thus, in this embodiment, the welding marks are generated on the notched surfaces 47a, 47b of the notched portion 47. Therefore, when viewed in a direction perpendicular to the surface 41a of the first member 40, the welding marks are unlikely to protrude from the edge of the surface 41a of the first member 40.

The negative electrode collector terminal 28 is a terminal for inputting and outputting electric power from the electrode body 20, and is disposed on the underside of the sealing plate 12, in other words, inside the case body 11. In this embodiment, the negative electrode collector terminal 28 is made of copper.

The negative electrode collector terminal 28 is a long plate-like member extending along the height direction of the secondary battery 1 (the short direction of the electrode body 20). As shown in FIG. 2, the negative electrode collector terminal 28 of this embodiment has an electrode connection portion 28a at its lower end that is joined to the negative electrode terminal joint portion 22 of the electrode body 20. As shown in FIG. 3, the negative electrode collector terminal 28 has a terminal connection portion 28b at its upper end that has a through hole 28c formed through the upper and lower surfaces for inserting the shaft portion 55 of the negative electrode external terminal 26 therethrough.

The negative electrode insulating member 30 is a plate-shaped member made of an insulating material, and in this embodiment, is made of PFA resin. As shown in FIG. 3, the negative electrode insulating member 30 in this embodiment has a through hole 30a formed in the center when viewed from above, penetrating the top and bottom surfaces, for inserting the shaft portion 55 of the negative electrode external terminal 26 therethrough.

The negative electrode gasket 32 is a member made of an insulating material, and in this embodiment, is a member made of PFA resin. The negative electrode gasket 32 in this embodiment has a base portion 33, a second frame portion 34, and a tube portion 35.

The base 33 is a plate-like portion that is rectangular when viewed from above. A through hole 33c is formed in the center of the base 33 when viewed from above, penetrating the upper and lower surfaces (front and back surfaces) for inserting the shaft portion 55 of the negative external terminal 26 therethrough.

The second frame portion 34 is a rectangular portion in top view that extends upward from the outer edge of the surface 33a of the base portion 33. The second frame portion 34 is formed so that its upper end surface is located above the notch portion 47 in the up-down direction and below the surface 41a of the first member 40 when the first member 40 of the negative electrode external terminal 26 is placed within the frame of the second frame portion 34.

The tube portion 35 is a cylindrical portion extending downward from the opening edge of the through hole 33c on the back surface 33b of the base 33. The inside of the tube portion 35 is in communication with the through hole 33c of the base 33, and the shaft portion 55 of the negative external terminal 26 is inserted into the tube.

In this embodiment, the negative electrode gasket 32 is disposed on the upper surface of the other end of the longitudinal direction of the sealing plate 12 with the cylindrical portion 35 inserted through the through hole 12a and the back surface 33b of the base 33 abutting the upper surface of the sealing plate 12. The negative electrode external terminal 26 is disposed within the frame of the second frame portion 34 of the negative electrode gasket 32 with the shaft portion 55 of the second member 50 inserted through the through hole 33c of the negative electrode gasket 32 and the inside of the cylindrical portion 35, and the back surface 41b of the first member 40 and the back surface 51b of the second member 50 abutting the surface 33a of the base 33 in the negative electrode gasket 32. In this embodiment, when the negative electrode external terminal 26 is disposed within the frame of the second frame portion 34 of the negative electrode gasket 32, a gap S is formed between the cutout surfaces 47a, 47b and the frame inner surface 34a. The negative current collector terminal 28 is disposed below the negative insulating member 30 disposed on the underside of the other longitudinal end of the sealing plate 12. In this embodiment, the shaft portion 55 of the negative external terminal 26 is inserted into the through hole 30a of the negative insulating member 30 and the through hole 28c of the negative current collector terminal 28, and the crimp portion 56 protruding from the terminal connection portion 28b is crimped, thereby joining the negative external terminal 26 and the negative current collector terminal 28. The electrode connection portion 28a of the negative current collector terminal 28 is welded to the negative terminal joint portion 22. In this embodiment, the negative electrode external terminal 26 and the sealing plate 12 are insulated by the negative electrode gasket 32, the negative electrode current collector terminal 28 and the sealing plate 12 are insulated by the negative electrode insulating member 30, and the negative electrode gasket 32 (specifically, the cylindrical portion 35) maintains airtightness between the through hole 12a of the sealing plate 12 and the shaft portion 55 of the negative electrode external terminal 26.

Regarding the positive electrode side of this embodiment, the positive electrode external terminal 25 is a single aluminum member having a shape similar to that of the negative electrode external terminal 26, unlike the negative electrode external terminal 26 which is formed by joining two members, the first member 40 and the second member 50, and the positive electrode current collector terminal 27 is also made of aluminum. The positive electrode gasket 31 and the positive electrode insulating member 29 have the same structure as the negative electrode gasket 32 and the negative electrode insulating member 30, respectively.

Although detailed description is omitted, in the positive electrode side of this embodiment, a positive electrode external terminal 25 and a positive electrode gasket 31 are disposed on the upper surface side of one longitudinal end side of the sealing plate 12, and a positive electrode collector terminal 27 and a positive electrode insulating member 29 are disposed on the lower surface side, and the positive electrode external terminal 25 and the positive electrode collector terminal 27 are joined by crimping the crimping portion protruding from the terminal connection portion. In addition, the electrode connection portion 27a of the positive electrode collector terminal 27 is welded to the positive electrode terminal joint portion 21. The positive electrode external terminal 25 and the sealing plate 12 are insulated by the positive electrode gasket 31, and the positive electrode collector terminal 27 and the sealing plate 12 are insulated by the positive electrode insulating member 29.

In the secondary battery 1 of this embodiment having the above configuration, the weld marks due to ultrasonic welding are generated on the notched surfaces 47a and 47b of the first member 40, but are not generated on the surface 41a of the first member 40, which is the busbar welding surface, or on the shaft portion 55 of the second member 50, which will be located on the inside of the secondary battery 1 (the inside of the case body 11), or on the crimped portion 56 formed on the shaft portion 55. Therefore, with this secondary battery 1, a wide busbar welding area can be secured, and the generation of foreign matter inside the secondary battery 1 due to ultrasonic welding can be suppressed.

In addition, in the secondary battery 1 of this embodiment, the first member 40 and the second member 50 are joined at two locations: the joining location between the first horn side joining surface 44 and the first anvil side joining surface 53, and the joining location between the second horn side joining surface 45 and the second anvil side joining surface 54. This improves the joining strength between the first member 40 and the second member 50.

In addition, in the secondary battery 1 of this embodiment, when viewed in a direction perpendicular to the surface 41a of the first member 40, the weld marks generated on the cutout surfaces 47a and 47b are unlikely to protrude from the surface edge of the first member 40, and a gap S is formed between the cutout surfaces 47a and 47b and the frame inner surface 34a of the second frame portion 34 of the negative electrode gasket 32. This makes it possible to avoid contact between the weld marks generated on the cutout surfaces 47a and 47b and the negative electrode gasket 32, and suppresses adverse effects associated with contact (such as reduced insulation).

[Method of manufacturing negative electrode external terminal 26]
Next, a method for manufacturing the negative electrode external terminal 26, which is a dissimilar material joint member, will be described with reference to Figs. 6 and 7. Fig. 6 is a cross-sectional view that shows a method for ultrasonically welding the first member 40 and the second member 50. Fig. 7 is a top view that shows a method for ultrasonically welding the first member 40 and the second member 50. In the figure, the positions of the horn H and the anvil A during the first ultrasonic welding are shown by solid lines, and the positions of the horn H and the anvil A during the second ultrasonic welding are shown by two-dot chain lines. Also, the shaded parts in Figs. 6 and 7 indicate the joint parts.

The method for manufacturing the negative electrode external terminal 26 includes an accommodation step and an ultrasonic welding step. The accommodation step is a step of accommodating at least a portion of the second member 50 in the accommodation recess 42 of the first member 40 so that the first anvil side joining surface 53 faces the first horn side joining surface 44.

Specifically, in this embodiment, the plate-shaped portion 51 of the second member 50 is accommodated in the accommodation recess 42 of the first member 40 so that the first horn side joining surface 44 faces the first anvil side joining surface 53, and the second horn side joining surface 45 faces the second anvil side joining surface 54 (see FIG. 6).

The ultrasonic welding process is a process in which the direction perpendicular to the first horn side bonding surface 44 and the first anvil side bonding surface 53 is defined as the first direction X, the first member 40 is fixed by the anvil A on the side of the first anvil side bonding surface 53 in the first direction X, the horn H is pressed against the outer surface of the first member 40 along the first direction X from the side of the first horn side bonding surface 44 in the first direction X, and ultrasonic vibrations are applied in a direction parallel to the first horn side bonding surface 44 and the first anvil side bonding surface 53 to bond the first horn side bonding surface 44 and the first anvil side bonding surface 53.

Specifically, in this embodiment, an ultrasonic welding device equipped with a horn H and anvil A is used. The horn resonates with ultrasonic vibrations emitted from the oscillator and applies vibrations of a frequency equal to or higher than the ultrasonic frequency range to the object, and the anvil A is a base that supports the object. In this embodiment, first, as shown in Figs. 6 and 7, the anvil A is pressed against the cutout surface 47b on the side of the first anvil side joining surface 53 in the first direction X, and the horn H is pressed against the cutout surface 47a of the first member 40 along the first direction X from the side of the first horn side joining surface 44 in the first direction X to apply pressure. Then, in this state, the horn H applies ultrasonic vibrations in a direction parallel to the first horn side joining surface 44 and the first anvil side joining surface 53 (direction perpendicular to the pressure direction), and the first horn side joining surface 44 and the first anvil side joining surface 53 are joined.

Next, as shown in FIG. 7, the anvil A is pressed against the notch surface 47a on the side of the second anvil side joining surface 54 in the first direction X, and the horn H is pressed against the notch surface 47b of the first member 40 along the first direction X from the side of the second horn side joining surface 45 in the first direction X. In other words, the horn H pressed against the notch surfaces 47a, 47b and the anvil A are switched. Then, in this state, the horn H applies ultrasonic vibrations in a direction parallel to the second horn side joining surface 45 and the second anvil side joining surface 54, joining the second horn side joining surface 45 and the second anvil side joining surface 54.

Thus, in the manufacturing method of the negative electrode external terminal 26 of this embodiment, contact marks due to ultrasonic welding between the first horn side joint surface 44 and the first anvil side joint surface 53, and between the second horn side joint surface 45 and the second anvil side joint surface 54, are generated on the outer surface (notch surfaces 47a, 47b) of the accommodation recess 42. In other words, according to the manufacturing method of the negative electrode external terminal 26 of this embodiment, it is possible to suitably manufacture a negative electrode external terminal 26 that does not have welding marks on the surface 41a of the first member 40, which is the busbar welding surface, the shaft portion 55 of the second member 50 that will be located on the inside of the secondary battery 1 (the inside of the case body 11), or the crimping portion 56 formed on the shaft portion 55.

[Another embodiment]
[1] In the above embodiment, the first member 40 is provided with the notch 47, but the present invention is not limited to this, and may have a configuration in which the notch 47 is not formed. Even in this configuration, no welding marks due to ultrasonic welding are generated on the surface 41a of the first member 40, which is the busbar welding surface, or on the portion that will be located on the inside of the secondary battery 1 (the inside of the case body 11), so that a wide busbar weldable area can be secured, and furthermore, generation of foreign matter on the inside of the secondary battery 1 due to ultrasonic welding can be suppressed.

[2] In the above embodiment, the first member 40 has the second horn side joining surface 45, the second member 50 has the second anvil side joining surface 54, the first horn side joining surface 44 and the first anvil side joining surface 53 are joined, and the second horn side joining surface 45 and the second anvil side joining surface 54 are joined, so that the first member 40 and the second member 50 are joined at two points in total. However, the present invention is not limited to such an embodiment. For example, the first member 40 may have only the first horn side joining surface 44 and the first anvil side joining surface 53, the first horn side joining surface 44 and the first anvil side joining surface 53 are joined, and the first member 40 and the second member 50 are joined at one point. Even in such an embodiment, the busbar welding area can be secured widely, and the generation of foreign matter inside the secondary battery 1 due to ultrasonic welding can be suppressed, as in the above embodiment.
In addition, one or both of a pair of surfaces 43b parallel to the longitudinal direction of the inner surface 43 of the accommodation recess 42 formed in the first member 40 and one or both of a pair of surfaces 52b parallel to the longitudinal direction of the outer circumferential surface 52 of the plate-like portion 51 of the second member 50 may be joined as the horn-side joining surface or the anvil-side joining surface. In such an embodiment, the number of joining points between the first member 40 and the second member 50 is increased, and therefore the joining strength between the first member 40 and the second member 50 can be improved.

[3] In the above embodiment, the first member 40 is made of aluminum and the second member 50 is made of copper, but this is not limited to the above, and various metals and alloys with good electrical conductivity can be used as the materials for the first member 40 and the second member 50.

The configurations disclosed in the above embodiment (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided no contradictions arise. Furthermore, the embodiments disclosed in this specification are merely examples, and the present invention is not limited to these embodiments. Appropriate modifications can be made without departing from the scope of the present invention.

11: Case body (housing)
12: Sealing plate (lid)
20: Electrode body 25: Positive electrode external terminal 26: Negative electrode external terminal (battery terminal)
27: Positive electrode current collector terminal 28: Negative electrode current collector terminal (current collector terminal)
40: First member 41a: Surface (bus bar welding surface)
42: Receiving recess 43: Inner surface 46: Outer circumferential surface (outer surface of the first member)
46a: A pair of surfaces (a pair of side surfaces)
47: Notch portion 44: First horn side joint surface 45: Second horn side joint surface 50: Second member 52: Outer peripheral surface (outer surface of the second member)
53: First anvil side joining surface 54: Second anvil side joining surface

Claims (6)

A battery terminal comprising a first member and a second member made of metal,
The first member is
A plate-shaped member having a bus bar welding surface on one surface,
An accommodating recess is formed on the rear surface thereof and has a first horn side bonding surface which is an inner surface parallel to the thickness direction thereof,
The second member is
A first anvil-side joint surface is provided on the outer surface.
At least a portion of the first anvil-side bonding surface is accommodated in the accommodation recess so as to face the first horn-side bonding surface,
The battery terminal has the first horn side joining surface and the first anvil side joining surface joined by ultrasonic welding. The first member is
The plate has a pair of side surfaces that are parallel to the thickness direction and parallel to each other,
2 . The battery terminal according to claim 1 , wherein an area of the pair of side surfaces corresponding to the first horn side joint surface in at least the thickness direction is a notch portion in which the distance between the side surfaces is shorter than that on the front surface side. the accommodating recess has a second horn-side bonding surface that is an inner surface parallel to the thickness direction and facing the first horn-side bonding surface with the second member therebetween,
the second member has a second anvil-side joint surface that is an outer surface facing the second horn-side joint surface,
2. The battery terminal according to claim 1, wherein the second horn side joining surface and the second anvil side joining surface are joined by ultrasonic welding. The first member is made of aluminum,
The battery terminal according to any one of claims 1 to 3, wherein the second member is made of copper. A housing having an opening;
a cover for sealing an opening of the housing;
A current collecting terminal disposed inside the housing;
a battery terminal electrically connected to the current collecting terminal;
The battery terminal is
The first member and the second member are made of metal.
The first member is
A plate-shaped member having a bus bar welding surface as a surface thereof,
An accommodating recess is formed on the rear surface thereof and has a first horn side bonding surface which is an inner surface parallel to the thickness direction thereof,
The second member is
A first anvil-side joining surface is provided on the outer surface.
At least a portion of the first anvil-side bonding surface is accommodated in the accommodation recess so as to face the first horn-side bonding surface,
the first horn side joining surface and the first anvil side joining surface are joined by ultrasonic welding,
A secondary battery in which a surface of the first member is located outside the lid, and the second member is electrically connected to the current collecting terminal inside the casing. A method for manufacturing a battery terminal by joining a first member, which is a metal plate-like member and has an accommodating recess formed therein, the first member having an opening on a rear surface and a first horn-side bonding surface that is an inner surface parallel to a thickness direction, to a second metal member having a first anvil-side bonding surface on an outer surface thereof,
an accommodating step of accommodating at least a portion of the second member in an accommodating recess of the first member such that the first anvil-side bonding surface faces the first horn-side bonding surface;
a first direction being a direction perpendicular to the first horn side bonding surface and the first anvil side bonding surface, a first member being fixed with an anvil on the side of the first anvil side bonding surface in the first direction, a horn being pressed against an outer surface of the first member along the first direction from the side of the first horn side bonding surface in the first direction to apply ultrasonic vibrations in a direction parallel to the first horn side bonding surface and the first anvil side bonding surface, thereby bonding the first horn side bonding surface and the first anvil side bonding surface.

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