JP2024011563A - Conductive member for battery and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive member for a battery with excellent conduction reliability and a method for manufacturing the conductive member.

SOLUTION: A method for manufacturing a conductive member for a battery disclosed herein includes the following steps: (1) a projection forming step of forming a projection 92p on a second metal member 92X; and (2) a joining step of placing a first metal member 91X on a recess 312 of a die 310 of a crimping device 300, overlapping, on top of that, a portion where the projection 92p of the second metal member 92X is formed, then press-fitting a punch 320 into the recess 312 of the die 310, forming a resistance weld portion by letting welding current flow to the die 310 and the punch 320 using a current supply unit 330 while pressing the projection 92p against the first metal member 91X, and plastically deforming the first metal member 91X and the second metal member 92X to form a caulked joint portion around the resistance weld portion.

SELECTED DRAWING: Figure 6

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a conductive member for a battery and a method for manufacturing the same.

Conventionally, a bonded body formed by bonding a plurality of members has been used as a conductive member for a battery. Prior art documents related to this include Patent Documents 1 and 2. For example, Patent Document 1 describes that the current collector foil laminated portion of the electrode body and the current collector plate are caulked and then resistance welded.

Unexamined Japanese Patent Publication No. 2015-5456 Japanese Patent Application Publication No. 3-216282

However, according to the study of the present inventor, when resistance welding is performed after caulking as in Patent Document 1, the contact area between the current collector foil laminated portion and the current collector plate becomes large, and during resistance welding, The current will diverge. Therefore, current paths are scattered at multiple locations, and the strength of the nugget (resistance welded portion) becomes weak. Furthermore, if a large current is applied to increase the strength of the nugget, the nugget becomes more brittle. As a result, when an external force such as vibration or shock is applied from the outside during use of the battery, the nugget may be destroyed, leading to unstable conduction or connection failure. Therefore, there is a need for a conductive member for batteries that has high continuity reliability.

The present invention has been made in view of the above circumstances, and its main purpose is to provide a conductive member for a battery with excellent conduction reliability and a method for manufacturing the same.

According to the present invention, the following step: preparing a first metal member having a plate-like portion and a second metal member having a plate-like portion, and forming a projection on the plate-like portion of the second metal member. Step: Prepare a caulking device including a die having a recess, a punch press-fitted into the recess, and a current supply unit that supplies welding current to the die and the punch, and place the first caulking device on the recess of the die. After placing the plate-shaped portion of the metal member and overlapping the portion of the second metal member with the projection formed thereon, the punch is press-fitted into the recess of the die, and the projection is placed on top of the plate-shaped portion of the second metal member. A resistance weld is formed by applying a welding current to the die and the punch using the current supply section while pressing against the metal member, and plastically deforms the first metal member and the second metal member to form the resistance weld. A method of manufacturing a conductive member for a battery is provided, including a joining step of forming a caulked joint around a welded part.

In the present invention, after forming a projection (protrusion) on one metal member, caulking is performed while applying a welding current to the two metal members. As a result, compared to the case where resistance welding is performed after caulking as in Patent Document 1, for example, the welding current can be concentrated on the projection, and a relatively large nugget can be formed. Therefore, a relatively small welding current is required, and a high-quality resistance weld with high mechanical strength can be formed. Further, in the present invention, since a plastically deformed portion is formed around the resistance weld, even if stress such as vibration or impact is applied from the outside, force is hardly applied to the resistance weld. Therefore, it becomes easier to maintain the state in which the first metal member and the second metal member are in close contact with each other. With the above effects, the conductive connection between the first metal member and the second metal member can be stably maintained, and the conduction reliability can be improved.

According to the present invention, a conductive member for a battery includes a first metal member having a plate-like portion, a second metal member having a plate-like portion, and a joint between the first metal member and the second metal member. provided. The joint portion includes a resistance welded portion formed by resistance welding the first metal member and the second metal member, and a resistance welded portion provided around the resistance welded portion, and the plate-like portion of the first metal member and the and a caulked joint formed by plastically deforming the plate-like portion of the second metal member.

The electrically conductive member for a battery according to the present invention includes two types of joints that are joined by different methods, namely, a resistance welding part and a caulking joint. A resistance weld can be a relatively less rigid joint than a plastically deformed part. By arranging such a resistance welded portion inside the plastically deformed portion, even if stress such as vibration or impact is applied from the outside, force is less likely to be applied to the resistance welded portion. Therefore, it becomes easier to maintain the state in which the first metal member and the second metal member are in close contact with each other. With such a configuration, the conductive connection between the first metal member and the second metal member can be stably maintained, and the reliability of conduction can be improved over a long period of time.

FIG. 1 is a perspective view schematically showing an assembled battery according to an embodiment. FIG. 2 is a longitudinal cross-sectional view of the battery of FIG. 1. 3 is a perspective view schematically showing the bus bar of FIG. 1. FIG. 4 is a plan view schematically showing the bus bar of FIG. 1. FIG. FIG. 5 is a longitudinal cross-sectional view taken along line V-V in FIG. 4. FIGS. 6(1) and 6(2) are schematic diagrams illustrating the manufacturing process of the bus bar of FIG. 1. FIG. 7(1) is a cross-sectional SEM observation image of the joint, and FIG. 7(2) is an enlarged cross-sectional SEM observation image of the main part of (1). FIGS. 8(1) and 8(2) are diagrams corresponding to FIG. 6 illustrating a manufacturing process according to a modification.

Hereinafter, preferred embodiments of the technology disclosed herein will be described with reference to the drawings. Further, matters other than those specifically mentioned in this specification that are necessary for carrying out the present invention (for example, the general configuration and manufacturing process of assembled batteries and batteries that do not characterize the present invention) are as follows: This can be understood as a matter of design by a person skilled in the art based on the prior art in the field. The present invention can be implemented based on the content disclosed in this specification and the common general knowledge in the field.

<Assembled battery 100>
FIG. 1 is a perspective view of the assembled battery 100. The assembled battery 100 includes a plurality of batteries 10 and a plurality of bus bars 90 that electrically connect the plurality of batteries 10 to each other. The bus bar 90 is a conductive connecting member that connects the terminals of the plurality of batteries 10. The number of bus bars 90 used in the assembled battery 100 is typically (number of batteries - 1). The bus bar 90 is an example of a "battery conductive member" disclosed herein.

In addition, in the following drawings, the same reference numerals are given to members and parts that have the same function, and overlapping explanations may be omitted or simplified. Further, in the drawings below, the symbols U, D, F, Rr, L, and R represent upper, lower, front, rear, left, and right, respectively, and the symbol X represents the stretching direction along the long side of the battery 10, The symbol Y represents the arrangement direction of the batteries 10 orthogonal to the symbol X, and the symbol Z represents the height direction of the batteries 10, respectively. However, these directions are merely for convenience of explanation, and do not limit the installation form of the assembled battery 100 in any way.

The plurality of batteries 10 are all flat and rectangular, and have the same shape here. The plurality of batteries 10 are lined up in a line along the arrangement direction Y so that a pair of flat side surfaces (wide sides) face each other. Note that the plurality of batteries 10 may be held integrally by a restraint mechanism such as a restraint band. The plurality of batteries 10 are electrically connected in series here by a bus bar 90. However, the shape, size, number, arrangement, connection method, etc. of the batteries 10 constituting the assembled battery 100 are not particularly limited and can be changed as appropriate. Further, between the plurality of batteries 10, for example, a heat radiating member for efficiently dissipating heat generated by the batteries 10, a spacer as a length adjusting means, etc. may be arranged.

Note that in this specification, the term "battery" refers to all electricity storage devices that can extract electrical energy, and is a concept that includes primary batteries and secondary batteries. Furthermore, in this specification, the term "secondary battery" refers to any electricity storage device that can be repeatedly charged and discharged by moving charge carriers between a positive electrode and a negative electrode via an electrolyte. The electrolyte may be a liquid electrolyte (electrolytic solution), a gel electrolyte, or a solid electrolyte. Secondary batteries include so-called storage batteries (chemical batteries) such as lithium ion secondary batteries and nickel-hydrogen batteries, and capacitors (physical batteries) such as electric double layer capacitors.

FIG. 2 is a longitudinal cross-sectional view of the battery 10. The battery 10 includes an electrode body 20, a battery case 30, a positive terminal 40, and a negative terminal 50. Although not shown, the battery 10 further includes an electrolyte here. The battery 10 is constructed by housing an electrode body 20 and an electrolyte in a battery case 30. Battery 10 is typically a secondary battery, here a lithium ion secondary battery. The configuration of the battery 10 may be the same as the conventional one and is not particularly limited.

The electrode body 20 is a wound electrode body in which a strip-shaped positive electrode 21 and a strip-shaped negative electrode 22 are laminated with two strip-shaped separators 23 and 24 in between and wound in the longitudinal direction. However, the electrode body 20 may be a laminated electrode body in which a rectangular positive electrode and a rectangular negative electrode are stacked in an insulated state.

The positive electrode 21 includes a foil-like positive electrode current collector 21a and a positive electrode mixture layer 21b fixed on the positive electrode current collector 21a. The positive electrode current collector 21a is made of a conductive metal such as aluminum, aluminum alloy, nickel, stainless steel, or the like. The positive electrode current collector 21a is made of aluminum here. The positive electrode mixture layer 21b includes a positive electrode active material (for example, a lithium transition metal composite oxide) that can reversibly insert and release charge carriers. In addition, at one side edge of the electrode body 20 in the stretching direction is provided.

The negative electrode 22 includes a foil-shaped negative electrode current collector 22a and a negative electrode mixture layer 22b fixed on the negative electrode current collector 22a. The negative electrode current collector 22a is made of conductive metal such as copper, copper alloy, nickel, and stainless steel. The negative electrode current collector 22a is made of a different metal species from the positive electrode current collector 21a. The negative electrode current collector 22a is made of copper here. The negative electrode mixture layer 22b contains a negative electrode active material (for example, a carbon material such as graphite) that can reversibly occlude and release charge carriers. In addition, on the other side edge of the electrode body 20 in the stretching direction is provided.

The separators 23 and 24 are insulating resin sheets in which a plurality of fine through holes through which charge carriers can pass are formed. The electrolyte is, for example, a non-aqueous electrolytic solution containing a non-aqueous solvent and a supporting salt such as a lithium salt. However, the electrolyte may be in a solid state (solid electrolyte) and may be integrated with the positive electrode 21 and the negative electrode 22. In this case, the electrode body 20 does not need to have the separators 23 and 24.

The battery case 30 is a housing that houses the electrode body 20. Here, the battery case 30 is formed into a flat rectangular parallelepiped shape (square) with a bottom. However, in other embodiments, the battery case 30 may have any shape such as a cylinder. The battery case 30 is made of a lightweight metal material with good thermal conductivity, such as aluminum, aluminum alloy, or stainless steel. The battery case 30 includes a square case body 32 having an opening on the top surface, and a plate-shaped lid 34 that closes the opening of the case body 32. A positive electrode terminal 40 and a negative electrode terminal 50 are attached to the lid body 34. The positive electrode terminal 40 and the negative electrode terminal 50 are arranged at both left and right ends of the battery 10 in the stretching direction X, respectively. The battery 10 is charged and discharged via a positive terminal 40 and a negative terminal 50.

Positive electrode terminal 40 is electrically connected to positive electrode 21 . The positive electrode terminal 40 is made of metal such as aluminum, aluminum alloy, nickel, stainless steel, etc., for example. The positive electrode terminal 40 may be made of the same metal type as the positive electrode current collector 21a. The positive electrode terminal 40 is made of aluminum here. The positive electrode terminal 40 includes a positive internal terminal 42 extending along the height direction Z and a plate-shaped positive external terminal 44 extending along the upper surface of the lid 34 . The positive electrode internal terminal 42 has an upper end portion 42a that penetrates the lid body 34 and is exposed to the outside of the battery case 30, and a lower end portion that is connected to the positive electrode 21 (specifically, the positive electrode tab portion 21c) inside the battery case 30. 42b. The positive external terminal 44 is connected to the upper end 42a of the positive internal terminal 42 outside the battery case 30. An insulating member 46 is disposed between the lid 34 and the positive external terminal 44 to prevent direct contact between the lid 34 and the positive external terminal 44.

The negative electrode terminal 50 is electrically connected to the negative electrode 22. The negative electrode terminal 50 is made of metal such as copper, copper alloy, nickel, stainless steel, etc., for example. The negative electrode terminal 50 may be made of the same metal type as the negative electrode current collector 22a. The negative electrode terminal 50 is made of copper here. The negative electrode terminal 50 includes a negative internal terminal 52 extending along the height direction Z and a plate-shaped negative external terminal 54 extending along the upper surface of the lid 34 . The negative electrode internal terminal 52 has an upper end portion 52a that penetrates the lid body 34 and is exposed to the outside of the battery case 30, and a lower end portion that is connected to the negative electrode 22 (specifically, the negative electrode tab portion 22c) inside the battery case 30. 52b, and a bent portion 52c provided between the upper end portion 52a and the lower end portion 52b. The negative external terminal 54 is connected to the upper end 52a of the negative internal terminal 52 outside the battery case 30. An insulating member 56 is disposed between the lid 34 and the negative external terminal 54 to prevent direct contact between the lid 34 and the negative external terminal 54.

In this embodiment, the upper end portions of the positive external terminal 44 and the negative external terminal 54 are each formed into a rectangular flat plate shape. The positive external terminal 44 and the negative external terminal 54 each have a flat surface parallel to the top surface of the lid 34. In the present embodiment, the width of the positive external terminal 44 and the negative external terminal 54 in the stretching direction X is longer than the width in the arrangement direction Y, respectively. However, the shape, size, arrangement, etc. of the positive electrode terminal 40 and the negative electrode terminal 50 are not particularly limited, and can be changed as appropriate.

Bus bar 90 is a conductive member used to electrically connect multiple batteries 10. Here, the bus bar 90 electrically connects the positive terminal 40 of the first battery 10 and the negative terminal 50 of the second battery 10 that are adjacent to each other in the arrangement direction Y. The bus bar 90 is arranged here so as to cover the flat surfaces of the positive electrode terminal 40 and the negative electrode terminal 50. The bus bar 90 is joined to the flat surfaces of the positive electrode terminal 40 and the negative electrode terminal 50 by a conventionally known joining method such as laser welding. A not-shown joint (typically a welded joint) is formed at the portion where the flat surface and the bus bar 90 are connected. Thereby, the bus bar 90 is integrated with the positive electrode terminal 40 and the negative electrode terminal 50.

3 is a perspective view of the bus bar 90, and FIG. 4 is a plan view of the bus bar 90. As shown in FIGS. 3 and 4, the bus bar 90 is composed of two members, a first metal member 91 and a second metal member 92. The first metal member 91 and the second metal member 92 are integrated through a plurality of (here, two) joints 95 and are electrically connected to each other. Each of the plurality of joints 95 has a caulked joint 93 and a resistance weld 94.

The first metal member 91 is a member that is electrically connected to the positive electrode terminal 40 of the battery 10 . The first metal member 91 is made of a conductive metal such as aluminum, aluminum alloy, nickel, or stainless steel. It is preferable that the first metal member 91 is an alloy whose first component (component having the highest blending ratio in terms of mass ratio; the same applies hereinafter) is the same metal type or the same metal element as the positive electrode terminal 40. It is preferable that the first metal member 91 is mainly made of aluminum. The first metal member 91 is made of aluminum here. The first metal member 91 is formed, for example, by bending a single metal plate by press working or the like.

The first metal member 91 connects the first connection part 91a connected to the positive electrode terminal 40, the second connection part 91b connected to the second metal member 92, and the first connection part 91a and the second connection part 91b. It has a connecting part 91c. The connecting portion 91c extends along the arrangement direction Y. The connecting portion 91c has a flat plate shape here. However, in other embodiments, the connecting portion 91c may have a bent portion in a U-shape or the like. The first connecting portion 91a and the second connecting portion 91b extend in the stretching direction X from both ends of the connecting portion 91c in the arrangement direction Y. As shown in FIG. 3, the first connecting portion 91a and the second connecting portion 91b have a substantially L-shaped outer shape.

The first connecting portion 91a includes a plate-like portion 91a1 along the flat surface of the positive electrode terminal 40, and an extending portion 91a2 extending from the plate-like portion 91a1 to the connecting portion 91c. The plate-shaped portion 91a1 is a portion that comes into contact with the positive electrode terminal 40. The outer shape of the plate-like portion 91a1 is approximately rectangular here. In plan view, the outer shape of the plate-like portion 91a1 is preferably approximately the same as or smaller than the outer shape of the flat surface of the positive electrode terminal 40. The plate-like portion 91a1 has a thickness of approximately 0.01 to 5 mm, for example, approximately 0.1 to 1 mm. However, the shape, size, and thickness of the plate-like portion 91a1 are not particularly limited and can be changed as appropriate.

The plate-shaped portion 91a1 has a through hole 91h penetrating in the height direction Z. The through hole 91h is provided in the center of the plate-like portion 91a1. The through hole 91h is formed in a substantially square shape (for example, a substantially rectangular shape) in plan view. The through hole 91h serves as a guideline for indicating the position where the plate portion 91a1 is welded to the flat surface of the positive electrode terminal 40. It can also function as an escape route for gas and heat generated during welding and joining.

The second connecting portion 91b includes a plate-shaped portion 91b1 that extends along the flat second metal member 92, and an extension portion 91b2 that extends from the plate-shaped portion 91b1 to the connecting portion 91c. The outer shape of the plate-like portion 91b1 is approximately rectangular here. The outer shape of the plate-like portion 91b1 may be the same as that of the plate-like portion 91a1. In plan view, the outer shape of the plate-like portion 91b1 is preferably approximately the same as or smaller than the outer shape of the second metal member 92. The plate-like portion 91b1 has a thickness of approximately 0.01 to 5 mm, for example, approximately 0.1 to 1 mm. However, the shape, size, and thickness of the plate-like portion 91b1 are not particularly limited and can be changed as appropriate.

The plate-like portion 91b1 has a window portion 91w penetrating in the height direction Z. The window portion 91w is provided at the center of the plate-like portion 91b1. In the stretching direction X, the window portion 91w is located between the plurality of caulked joint portions 93. The window portion 91w is formed in a substantially square shape (for example, a substantially rectangular shape) in plan view. In plan view, the second metal member 92 is exposed from the window portion 91w.

The second metal member 92 is a member that is electrically connected to the negative electrode terminal 50 of the battery 10 . The second metal member 92 is made of a conductive metal such as copper, copper alloy, nickel, and stainless steel. For example, the first component of the second metal member 92 may be the same metal type as the first metal member 91 or may be a different metal type. The second metal member 92 is preferably the same metal type as the negative electrode terminal 50 or an alloy whose first component is the same metal element. The second metal member 92 is made of a different metal from the first metal member 91 here. It is preferable that the second metal member 92 is mainly made of copper. The second metal member 92 is made of copper here. The second metal member 92 may include a metal coating portion whose surface is coated with a metal such as Ni. The surface of the second metal member 92 may be laser roughened.

The second metal member 92 has a flat plate shape here. The second metal member 92 here consists of a plate-shaped portion. The second metal member 92 has one surface (the upper surface in FIG. 3) in contact with the second connecting portion 91b of the first metal member 91, and the opposite surface (the lower surface in FIG. 3) in contact with the negative electrode terminal 50. The outer shape of the second metal member 92 is approximately rectangular here. In plan view, the outer shape of the second metal member 92 is preferably approximately the same as or smaller than the outer shape of the flat surface of the negative electrode terminal 50. The second metal member 92 has a thickness of approximately 0.01 to 5 mm, for example, approximately 0.1 to 1 mm. However, the shape, size, and thickness of the second metal member 92 are not particularly limited and can be changed as appropriate.

The second metal member 92 has a through hole 92h that penetrates in the height direction Z. The through hole 92h is provided in the center of the second metal member 92. The through hole 92h is formed in a substantially square shape (for example, a substantially rectangular shape) in plan view. The through hole 92h has approximately the same size as the through hole 91h of the first metal member 91. The through hole 92h serves as a guideline for indicating the position where the second metal member 92 is welded to the flat surface of the negative electrode terminal 50. It can also function as an escape route for gas and heat generated during welding and joining.

The two joint portions 95 are provided in parallel in the stretching direction X that is orthogonal to the arrangement direction Y. Specifically, the two joint portions 95 are provided at both ends of the plate-like portion 91b1 of the first metal member 91 in the stretching direction X, respectively. Thereby, the bonding strength between the first metal member 91 and the second metal member 92 can be increased, and the reliability of conduction can be improved. The two joint parts 95 are provided outside the window part 91w in plan view. The two joint parts 95 are provided so as to sandwich the window part 91w in the stretching direction X. However, in other embodiments, the number of joints 95 may be one, or three or more (for example, four). The joint portions 95 may be provided at, for example, the four corners of the plate-like portion 91b1. FIG. 5 is a longitudinal cross-sectional view of the joint portion 95 taken along the line V-V in FIG.

The caulking joint 93 is a joint formed by caulking the plate-like portion 91b1 of the first metal member 91 and the flat second metal member 92 by plastically deforming them. As a result, even if the first metal member 91 and the second metal member 92 are made of different metals, for example, the first metal member 91 and the second metal member 92 can be suitably connected without using bolts, rivets, etc. Can be joined to Furthermore, the resistance of the bus bar 90 can be relatively reduced compared to the case where a third member (for example, a bolt or a rivet) is used. As shown in FIG. 5, the crimped joint 93 is provided around the resistance weld 94. As shown in FIG. In other words, the caulked joint portion 93 is provided so as to surround the resistance weld portion 94 .

As shown in FIG. 3, the caulking joint portion 93 projects upward from the plate-shaped portion 91b1 of the first metal member 91. As shown in FIG. The outer shape of the caulked joint portion 93 is approximately cylindrical here. As shown in FIG. 4, the caulked joint portion 93 has a substantially circular shape in plan view. However, the caulking joint portion 93 may have other shapes, such as a substantially square shape, an elliptical cylinder shape, a gourd-like shape in which two circles or ellipses are connected, or the like. Note that in this specification, the term "substantially quadrangular shape" refers to not only a complete quadrilateral shape (for example, a rectangular shape or a square shape), but also a shape in which the corner connecting two sides is rounded, or a corner. This term also includes shapes that have a notch in the part. Here, there are a plurality of caulked joints 93 (specifically, two).

As shown in FIG. 5, the caulked joint portion 93 includes a plastically deformed portion 93a, a convex portion 93b, and a neck portion 93c. The plastically deformed portion 93a includes a first metal member 91 and a second metal member 92. In the plastically deformed portion 93a, the first metal member 91 and the second metal member 92 are in contact with each other with a sufficient line length and are interlocked. The plastically deformed portion 93a is provided along the outer peripheral edge of the neck portion 93c. The plastically deformed portion 93a has a substantially cylindrical outer shape. The plastically deformed portion 93a is annular (here, substantially annular) in plan view. This increases the strength of the interlock. The convex portion 93b is made of the first metal member 91. The convex portion 93b projects upward. The convex portion 93b is annular (here, substantially annular) in plan view. The neck portion 93c is made of a second metal member 92. The neck portion 93c extends along the height direction Z. The neck portion 93c has a substantially cylindrical outer shape. The neck portion 93c constitutes the inner peripheral edge of the caulked joint portion 93.

The resistance welding portion 94 is a joint formed by resistance welding the plate-shaped portion 91b1 of the first metal member 91 and the flat second metal member 92. The resistance welding portion 94 may be a joint having relatively lower rigidity (brittle) than the caulking joint 93 . As shown in FIG. 5, the resistance weld portion 94 is provided inside the caulked joint portion 93 (specifically, inside the annular plastic deformation portion 93a). Specifically, it is provided at the center of the annular plastic deformation portion 93a. Thereby, the joint portion 95 (particularly the resistance weld portion 94) can be maintained stably, and the continuity reliability can be improved over a long period of time.

As shown in FIG. 4, the resistance welds 94 are provided inside the two caulked joints 93, respectively. The number of resistance welds 94 is the same as the number of caulked joints 93. There are a plurality of resistance welds 94 (specifically, two). In the stretching direction X, the two resistance welds 94 are provided at both ends of the plate-like portion 91b1 of the first metal member 91 here. This makes it easier to release gas and heat that may be generated during formation of the resistance welded portion 94 (during resistance welding), thereby suppressing the occurrence of joint defects (for example, weld defects).

<Method for manufacturing bus bar 90>
The bus bar 90 can be manufactured, for example, by a manufacturing method including (1) a projection forming step and (2) a bonding step in this order. Note that in the following, the first metal member 91 and the second metal member 92 before forming the joint portion 95 (before the joining process) will be distinguished from those after the formation, and will be referred to as the first metal member 91X and the second metal member. It's called 92X. Further, the manufacturing method disclosed herein may further include other steps at any stage. FIG. 6 is a schematic diagram illustrating a method of manufacturing the bus bar 90.

(1) In the projection forming step, a first metal member 91X having a plate-like portion and a second metal member 92X having a plate-like portion are prepared, and a projection (protrusion) 92p is formed on the plate-like portion of the second metal member 92X. This is the process of Note that this step is not essential, and can be omitted, for example, when the next step, that is, (2) the bonding step, is performed using the protrusion already present on the second metal member 92X.

The method of forming the projection 92p may be the same as the conventional method and is not particularly limited. In one example, the plate-shaped portion of the first metal member 91 is press-worked to partially bulge the plate-shaped portion to form a projection 92p having a predetermined shape. In this case, for example, first, a press mold 200 as shown in FIG. 6(1) is prepared. The mold 200 is used to perform so-called stretch molding to mold the projection 92p in a gently curved shape. The mold 200 includes a die 210 having a recess 212 and a punch 220 having a protrusion 222 press-fitted into the recess 212. The punch 220 is configured to be movable in a direction toward the die 210 and a direction away from the die 210 (height direction Z in FIG. 6(1)). The outer shape of the convex portion 222 is a circular dome shape here.

As shown in FIG. 6(1), in this step, the plate-shaped portion of the second metal member 92X is placed between the die 210 and the punch 220, and the pressing direction P (in this case, vertically downward) is indicated by the arrow. By moving the punch 220, the second metal member 92X is pressed. As a result, a portion of the second metal member 92X is pressed against the convex portion 222 and pushed out so as to protrude toward the inside of the concave portion 212. As a result, the plate-shaped portion of the second metal member 92X is formed into a shape that follows the convex portion 222 (in this case, a circular dome shape), and a projection 92p is formed. Note that the second metal member 92X typically deforms while the thickness of the plate-like portion remains substantially constant. The projection 92p has a shape in which the second metal member 92X is gently curved.

(2) The joining process is a process of joining the first metal member 91X and the second metal member 92X. More specifically, this is a step of forming a caulked joint 93 (more specifically, a plastically deformed portion 93a) and a resistance weld 94 between the first metal member 91X and the second metal member 92X at approximately the same time. Specifically, first, a caulking device is prepared. A conventionally known crimping device can be used. In one example, a crimping device 300 as shown in FIG. 6(2) is prepared. The caulking device 300 includes a die 310 having a recess 312, a punch 320 that is press-fitted into the recess 312, and a current supply section 330 that supplies welding current to the die 310 and the punch 320.

Die 310 and punch 320 are here made of metal. As the die 310 and the punch 320, commercially available tools used in the conventionally known TOX (trademark) crimping can be used. The opening of the recess 312 of the die 310 is larger than the outer shape of the projection 92p of the second metal member 92X. The recess 312 is formed to accommodate the projection 92p. The outer shape of the recess 312 is approximately cylindrical. The diameter of the recess 312 is preferably approximately three times or more, for example, three or more times, or four times or more, the diameter of the projection 92p. Although not particularly limited, the diameter of the recess 312 is preferably 1.5 to 5.0 mm. An annular groove 312a is formed on the lower surface of the recess 312.

The punch 320 is configured to be movable in a direction toward the die 310 and a direction away from the die 310 (height direction Z in FIG. 6(2)). The outer shape of the punch 320 is cylindrical here. The diameter of the punch 320 is smaller than the recess 312 of the die 310. The diameter of the punch 320 is preferably approximately 0.5 mm or more, for example, 1 mm or more smaller than the recess 312 of the die 310. Although not particularly limited, the diameter of the punch 320 is preferably 1.0 to 4.0 mm.

The current supply unit 330 is a mechanism for performing projection welding (specifically, embossed projection welding). The configuration of the current supply section 330 may be the same as the conventional one. The current supply section 330 may be of a capacitor type or an inverter type. The current supply unit 330 here includes an input terminal 332, a welding transformer 334 having a primary winding 334a and a secondary winding 334b, a pair of electrode tips 336, a first circuit 337, and a second circuit 338. , is equipped with. The input terminal 332 is connected to a DC power source or an AC power source and is configured to supply power to the welding transformer 334. Welding transformer 334 is driven, for example, by the output of an inverter circuit, and is configured to output welding current to a pair of electrode tips 336. The first circuit 337 is a circuit that connects one end of the secondary winding 334b of the welding transformer 334 and the die 310. The second circuit 338 is a circuit that connects the other end of the secondary winding 334b of the welding transformer 334 and the punch 320.

As shown in FIG. 6(2), in this step, the first metal member 91X and the second metal member 92X are placed between the die 310 and the punch 320, and the press direction P (here, , vertically downward) to press fit the punch 320 into the recess 312 of the die 310. Although not particularly limited, the pressure during press-fitting is preferably 500 to 2500N. Thereby, the caulked joint portion 93 with high joint strength can be stably formed.

At this time, by applying a welding current to the die 310 and the punch 320 using the current supply unit 330 while pressing the projection 92p against the first metal member 91X, the projection 92p is melted and a nugget N is formed. As the punch 320 is pushed in, the nugget N spreads in an annular shape centered on the apex of the projection 92p. As a result, a resistance weld 94 is formed at the interface between the first metal member 91X and the projection 92p. Therefore, the resistance welded portion 94 can be formed so that, in cross-sectional view, the center portion is the thickest and the thickness gradually becomes thinner toward the outer edge.

Further, by TOX (trademark) caulking, the first metal member 91 and the second metal member 92 are pushed into the recess 312 with the punch 320. As a result, the groove portion 312a is filled with the first metal member 91X to form the convex portion 93b. When the pressure is further continued, the second metal member 92 expands outward inside the first metal member 91, and the first metal member 91X and the second metal member 92X are formed by the recess 312 and the punch 320. It is plastically deformed to follow the shape of the space. As a result, a caulked joint portion 93 having an annular (circular here) neck portion 93c and a plastically deformed portion 93a is formed around the resistance weld portion 94. In other words, the resistance weld portion 94 is formed inside the annular plastic deformation portion 93a of the caulked joint portion 93, preferably at the center of the plastic deformation portion 93a.

FIG. 7(1) is a cross-sectional SEM observation image corresponding to the joint portion 95 in FIG. FIG. 7(2) is an enlarged cross-sectional SEM observation image of the main part of (1), specifically, the resistance welding part 94. As shown in FIG. 7(2), the resistance weld 94 is formed at the interface between the first metal member 91 and the second metal member 92. As shown in FIG. In the resistance welding portion 94, the metal type of the first metal member 91 and the metal type of the second metal member 92 are mixed. Note that in FIGS. 7(1) and 7(2), the vertical orientation is reversed from that in FIG.

As described above, in this embodiment, a projection (protrusion) 92p is first formed on the second metal member 92X, and then caulking (here, TOX (trademark) caulking) is performed while applying a welding current. Thereby, the welding current can be concentrated on the projection 92p, and a large nugget can be formed around the projection 92p. Therefore, it is not necessary to flow a large current, and a high-quality resistance welded portion 94 with high mechanical strength can be formed.

Further, by sandwiching and compressing the first metal member 91X and the second metal member 92X, an annular plastically deformed portion 93a is formed. Therefore, even if the first metal member 91X and the second metal member 92X are made of different metals, they can be suitably joined. Moreover, according to TOX (trademark) caulking, the nickel plating applied to the surface of the second metal member 92X is difficult to peel off, and the second metal member 92 can be stably welded to the bus bar 90 during manufacturing of the assembled battery 100.

Furthermore, since the resistance welding part 94 is a metallurgical joint that uses heat (Joule heat) generated by electrical resistance, it is a joint with relatively low strength (brittle) compared to the caulking joint 93. sell. By arranging such a resistance weld 94 on the inner peripheral side of the caulked joint 93, the resistance weld 94 can be stably maintained. Therefore, even if stress such as vibration or shock is applied from the outside, force is less likely to be applied to the resistance welding portion 94, and it becomes easier to maintain the state in which the first metal member 91 and the second metal member 92 are in close contact with each other for a long period of time. As a result, conduction reliability can be improved.

<Method for manufacturing assembled battery 100>
The assembled battery 100 includes, for example, a plurality of batteries 10 as described above and a bus bar 90, and connects the positive terminal 40 of one battery 10 and the negative terminal 50 of the other battery 10 via the bus bar 90. It can be manufactured by electrically connecting the Specifically, first, the plate-shaped portion 91a1 of the bus bar 90 is placed on the flat surface of the positive terminal 40 of one battery 10, and after alignment with the through hole 91h, the plate-shaped portion 91a1 of the bus bar 90 and the positive terminal are aligned. 40 are laser welded. Similarly, the plate portion 91b1 of the bus bar 90 and the second metal member 92 are placed on the flat surface of the negative terminal 50 of the other battery 10, and after alignment with the through hole 92h, the plate portion 91b1 is placed on the flat surface of the negative terminal 50 of the other battery 10. The second metal member 92 exposed through the opened window 91w and the negative electrode terminal 50 are laser welded. When laser welding the second metal member 92 and the negative electrode terminal 50, the wavelength of the laser is preferably 540 nm or less. Thereby, weldability can be improved.

Although the embodiments of the present invention have been described above, the above embodiments are merely examples. The present invention can be implemented in various other forms. The present invention can be implemented based on the content disclosed in this specification and the common general knowledge in the field. The technology described in the claims includes various modifications and changes to the embodiments exemplified above. For example, it is also possible to replace a part of the embodiment described above with other modifications, and it is also possible to add other modifications to the embodiment described above. Also, if the technical feature is not described as essential, it can be deleted as appropriate.

<Modification 1>
For example, in the above embodiment, as shown in FIGS. 6(1) and (2), one projection (protrusion) 92p is formed on the plate-shaped portion of the second metal member 92X in the (1) projection forming step. After that, in the (2) joining step, the first metal member 91X and the second metal member 92X were joined at one location. However, it is not limited to this. FIGS. 8(1) and (2) are diagrams corresponding to FIGS. 6(1) and (2) according to a modified example. In this modification, the joint portions 95 can be formed at a plurality of locations (here, two locations) substantially simultaneously. This modification is particularly effective when manufacturing a battery conductive member including a plurality of joints 95, as shown in FIG. 3, for example.

(1) In the projection forming step, as shown in FIG. 8(1), a plurality of molds 200 (two in this case) are prepared and arranged at predetermined intervals in the stretching direction X. Then, by pressing the plate-shaped portion of the second metal member 92X at a plurality of locations, a plurality of (here, two) projections 92p are formed substantially simultaneously. Thereby, the time required for this process can be shortened and work efficiency can be increased. Further, it is possible to maintain a predetermined interval between the plurality of projections 92p, and processing errors can be suppressed.

(2) In the joining process, a caulking device 400 is prepared as shown in FIG. 8(2). The caulking device 400 includes one die 410 having a plurality of (two in this case) recesses 412, 414, a plurality of punches 420a, 420b press-fitted into the plurality of recesses 412, 414, respectively, a die 410 and a punch 420a, A current supply section 430 that supplies a welding current to 420b is provided. Although the two recesses 412 and 414 have the same shape and the same size here, they may have different shapes or sizes.

The current supply unit 430 includes an input terminal 432, a welding transformer 434 having a primary winding 434a and a secondary winding 434b, a pair of electrode tips 436 attached to punches 420a and 420b, and a secondary winding 434b. It includes a first circuit 437 that connects one end to the first punch 420a, and a second circuit 438 that connects the other end of the secondary winding 434b to the second punch 420b. In this step, a welding current is passed through the plurality of punches 420a and 420b by the current supply unit 430, so that a conductive path is formed via the second metal member 92X, the first metal member 91X, and the die 410, and the plurality of nuggets N can be formed almost simultaneously. Thereby, the time required for this process can be shortened and work efficiency and productivity can be increased.

<Modification 2>
For example, in the embodiment described above, the battery conductive member was the bus bar 90. However, it is not limited to this. The conductive member for a battery may be, for example, the negative electrode terminal 50 or the negative internal terminal 52 that constitute the battery 10 in FIG. 2 . Specifically, for example, when the negative internal terminal 52 and the negative external terminal 54 are made of different metal materials (different types of metal materials), the connecting portion between the negative internal terminal 52 and the negative external terminal 54 is The disclosed joints, namely swaged joints and resistance welds, may be formed. In this case, for example, the negative internal terminal 52 can be understood as the second metal member, and the negative external terminal 54 can be understood as the first metal member. The negative internal terminal 52 may be made of a metal material mainly made of copper, and the negative external terminal 54 may be made of a metal material mainly made of aluminum.

Further, for example, when the upper end 52a and the lower end 52b of the negative electrode internal terminal 52 are made of different metal materials (different metal materials), the connecting portion between the upper end 52a and the lower end 52b, or the bent portion 52c The joints disclosed herein, namely swaged joints and resistance welds, may be formed nearby. In this case, for example, the upper end portion 52a can be understood as a first metal member, and the lower end portion 52b can be understood as a second metal member. The upper end portion 52a may be made of a metal material mainly made of aluminum, and the lower end portion 52b may be made of a metal material mainly made of copper.

<Applications of assembled battery 100>
The assembled battery 100 can be used for various purposes, but is typically used for applications where external forces such as vibrations and shocks are applied during use, typically for motors installed in various vehicles, such as passenger cars and trucks. It can be suitably used as a power source (driving power source). Although the type of vehicle is not particularly limited, examples thereof include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), and a battery electric vehicle (BEV).

As mentioned above, specific aspects of the technology disclosed herein include those described in the following sections.
Item 1: A projection forming step of preparing a first metal member having a plate-like portion and a second metal member having a plate-like portion, forming a projection on the plate-like portion of the second metal member, and forming a recess. A caulking device including a die having a die, a punch press-fitted into the recess, and a current supply section for supplying a welding current to the die and the punch is prepared, After placing a plate-shaped portion and overlapping the portion of the second metal member with the projection formed thereon, the punch is press-fitted into the recess of the die to press the projection onto the first metal member. At the same time, the current supply section applies a welding current to the die and the punch to form a resistance weld, and at the same time plastically deforms the first metal member and the second metal member to form a weld around the resistance weld. A method for manufacturing a conductive member for a battery, including a joining step of forming a caulked joint.
Item 2: The manufacturing method according to item 1, wherein the first metal member and the second metal member are made of different metals.
Item 3: The manufacturing method according to Item 1 or 2, wherein the battery conductive member is composed of two members, the first metal member and the second metal member.
Item 4: The manufacturing method according to any one of Items 1 to 3, wherein in the joining step, a plurality of the resistance welds and a plurality of the caulked joints are formed at once.
Item 5: The manufacturing method according to any one of Items 1 to 4, wherein the battery conductive member is a bus bar.
Item 6: The manufacturing method according to any one of Items 1 to 4, wherein the conductive member for a battery is a terminal of a battery.
Item 7: A first metal member having a plate-like portion, a second metal member having a plate-like portion, and a joint between the first metal member and the second metal member, the joint comprising: a resistance welded portion formed by resistance welding the first metal member and the second metal member; and a resistance welded portion provided around the resistance welded portion between the plate-shaped portion of the first metal member and the second metal member. A conductive member for a battery, comprising: a caulked joint formed by plastically deforming the plate-shaped portion.
Item 8: The conductive member for a battery according to Item 7, wherein the first metal member and the second metal member are made of different metals.
Item 9: The battery conductive member according to item 7 or 8, wherein the battery conductive member is composed of two members, the first metal member and the second metal member.
Item 10: The conductive member for a battery according to any one of Items 7 to 9, wherein there is a plurality of the joint parts, and the plurality of joint parts are arranged in a predetermined direction.
Item 11: The battery conductive member according to any one of Items 7 to 10, wherein the battery conductive member is a bus bar.
Item 12: The electrically conductive member for a battery according to any one of Items 7 to 10, wherein the electrically conductive member for a battery is a terminal of a battery.

10 Battery 40 Positive terminal 50 Negative terminal 90 Bus bar 91 First metal member 91a1 Plate portion 91a2 Extended portion 91b1 Plate portion 91b2 Extended portion 91h Through hole 91w Window portion 92 Second metal member 92h Through hole 93 Caulked joint portion 93a Plastic deformation Part 94 Resistance welding part 100 Battery pack 200 Press mold 300, 400 Caulking device 310, 410 Die 320, 420a, 420b Punch 330, 430 Current supply part

Claims (12)

a projection forming step of preparing a first metal member having a plate-like portion and a second metal member having a plate-like portion, and forming a projection on the plate-like portion of the second metal member;
A caulking device including a die having a concave portion, a punch press-fitted into the concave portion, and a current supply unit that supplies welding current to the die and the punch is prepared, and the first metal member is placed above the concave portion of the die. After placing the plate-like part of the second metal member on which the projection is formed, the punch is press-fitted into the recess of the die to transfer the projection to the first metal member. A resistance weld is formed by applying a welding current to the die and the punch using the current supply section while pressing the die and the punch, and plastically deforms the first metal member and the second metal member to form the resistance weld. a joining step of forming a caulked joint around the periphery of the
A method for manufacturing a conductive member for a battery. The manufacturing method according to claim 1, wherein the first metal member and the second metal member are made of different metals. The manufacturing method according to claim 1 or 2, wherein the battery conductive member is composed of two members, the first metal member and the second metal member. The manufacturing method according to claim 1 or 2, wherein in the joining step, a plurality of the resistance welds and a plurality of the caulked joints are formed at once. The manufacturing method according to claim 1 or 2, wherein the battery conductive member is a bus bar. The manufacturing method according to claim 1 or 2, wherein the battery conductive member is a battery terminal. a first metal member having a plate-like portion;
a second metal member having a plate-like portion;
a joint between the first metal member and the second metal member;
Equipped with
The joint portion is
a resistance welded portion formed by resistance welding the first metal member and the second metal member;
a caulking joint provided around the resistance welding portion and formed by plastically deforming the plate-like portion of the first metal member and the plate-like portion of the second metal member;
Conductive material for batteries. The electrically conductive member for a battery according to claim 7, wherein the first metal member and the second metal member are made of different metals. The electrically conductive member for a battery according to claim 7 or 8, wherein the electrically conductive member for a battery is comprised of two members, the first metal member and the second metal member. The electrically conductive member for a battery according to claim 7 or 8, wherein the number of the joints is plural, and the plurality of joints are arranged in a predetermined direction. The electrically conductive member for a battery according to claim 7 or 8, wherein the electrically conductive member for a battery is a bus bar. The electrically conductive member for a battery according to claim 7 or 8, wherein the electrically conductive member for a battery is a terminal of a battery.

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