CN214043930U

CN214043930U - Terminal for battery

Info

Publication number: CN214043930U
Application number: CN202023296105.6U
Authority: CN
Inventors: 北川尭生; 横田将幸; 石井尚宪; 中野裕文
Original assignee: Hitachi Metals Ltd; Aoyama Seisakusho Co Ltd
Current assignee: Aoyama Seisakusho Co Ltd; Proterial Ltd
Priority date: 2020-03-31
Filing date: 2020-12-30
Publication date: 2021-08-24
Anticipated expiration: 2030-12-30
Also published as: WO2021199518A1; JP7336025B2; JPWO2021199518A1

Abstract

The utility model provides a terminal for battery. A negative electrode terminal (20) as a battery terminal is provided with: a shaft portion (21); a flange part (22) extending from the side of the shaft part (21) toward the radial direction; and a recess (23) surrounded by a wall (24) extending further from the Cu layer (32) side end of the shaft (21). Wherein, in the axial section of the shaft part (21),the cross-sectional area of Cu crystal grains constituting a Cu portion (33) of the wall (24) and consisting of a Cu layer (32) is 10 [ mu ] m²Above and 100 μm²The following.

Description

Terminal for battery

Technical Field

The present invention relates to a battery terminal suitable for a lithium ion battery, for example, and particularly to a battery terminal including an Al layer made of pure Al or an Al-based alloy and a Cu layer made of pure Cu or a Cu-based alloy, and a method for manufacturing the battery terminal.

Background

Conventionally, as disclosed in patent No. 6014808, a battery terminal including a first metal layer made of an Al-based alloy and a second metal layer made of a Cu-based alloy is known.

The battery terminal disclosed in patent No. 6014808 includes a shaft portion and a flange portion radially extending from the shaft portion. In patent document 1, the battery terminal is fixed to another member by bending and caulking a Cu portion of the Cu layer at the tip of the shaft portion.

Although not described in patent publication 6014808, in order to bend and crimp the Cu portion at the tip end of the shaft portion of the battery terminal to fix the terminal to another member, the bent Cu portion is required to have mechanical properties capable of withstanding bending and crimping. In order to maintain a strong fixed state (crimped state) between the battery terminal and another member, the crimped Cu portion is required to have mechanical properties capable of withstanding the fixed state over time. Therefore, the inventors of the present application have conducted intensive studies and found the following problems: if the workability of the Cu portion is too poor, cracking occurs in the Cu portion when the Cu portion is bent and caulked. The following problems have also been found: if the workability of the Cu portion is too good, the Cu portion at the tip of the shaft portion of the battery terminal is bent and caulked to be fixed to another member, and then, when an external force such as vibration is applied to the Cu portion, cracking may occur.

SUMMERY OF THE UTILITY MODEL

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a battery terminal and a method for manufacturing the same, which can have mechanical characteristics suitable for being fixed to another member by bending and caulking a Cu portion at the tip of a shaft portion, and which can have mechanical characteristics suitable for maintaining the fixed state (caulking state).

The present inventors have conducted extensive studies to solve the above-described problems, and as a result, have found that a Cu portion at the tip of a shaft portion of a battery terminal is formed by a crystal grain having an appropriate cross-sectional area, and the Cu portion can have appropriate mechanical properties. Then, the present invention has been completed.

That is, the present invention provides, in a first aspect, a terminal for a battery, which is: an Al layer made of pure Al or an Al-based alloy and a Cu layer made of pure Cu or a Cu-based alloy are bonded in a state of being sequentially laminated, and the aluminum-clad laminate is provided with a shaft portion extending from the Al layer side to the Cu layer side, a flange portion extending from the side of the shaft portion in the radial direction, and a recess portion surrounded by a wall portion extending further from the tip of the shaft portion on the Cu layer side, wherein the cross-sectional area of Cu crystal grains of the wall portion constituting the Cu portion made of the Cu layer is 10 [ mu ] m in an axial cross-sectional surface of the shaft portion²Above and 100 μm²The following.

The utility model discloses a terminal for battery that first aspect provided, it possesses: a shaft portion extending from the Al layer side to the Cu layer side, a flange portion extending from the side of the shaft portion in the radial direction, and a recess portion surrounded by a wall portion extending to the Cu layer side of the tip of the shaft portion, wherein in a cross-sectional plane in the axial direction of the shaft portion, a cross-sectional area of Cu crystal grains of the wall portion constituting a Cu portion constituted by the Cu layer is 10 [ mu ] m²Above and 100 μm²The following. Accordingly, in the axial cross-sectional surface of the shaft portion, the cross-sectional area of the Cu crystal grains passing through the Cu portion of the wall portion constituting the Cu layer is 10 μm²Above and 100 μm²Hereinafter, the Cu portion at the tip of the shaft portion has an appropriate vickers hardness, and thus, sufficient workability can be obtained. Therefore, the shaft portion can have mechanical properties suitable for being bent and swaged at the Cu portion at the tip end of the shaft portion to be fixed to another member, and also have mechanical properties suitable for maintaining the fixed state (swaged state). In particular, in order to pass electricityThe Cu portion at the tip of the shaft portion of the cell terminal is bent and caulked to be fixed to another member, and the bent Cu portion is required to have mechanical properties capable of withstanding the bending and caulking. The cross-sectional area of Cu crystal grains is 10 μm²Above and 100 μm²The following Cu portion can have mechanical properties that can withstand bending and caulking, such as being less likely to break when bent and caulked. In order to maintain a strong fixed state (caulking state) between the battery terminal and another member, mechanical properties for maintaining the fixed state are required for the caulked Cu portion. The cross-sectional area of Cu crystal grains is 10 μm²Above and 100 μm²The Cu portion below can have mechanical properties that can withstand the fixed state over time, such as being less likely to break when an external force such as vibration is applied after the Cu portion is fixed to another member by bending and caulking.

In the battery terminal according to the first aspect of the present invention, it is preferable that the cross-sectional area of the Cu crystal grains constituting the Cu portion is 65 μm²The following. Accordingly, the cross-sectional area of the Cu crystal grains constituting the Cu portion was (10 μm)²Above) 65 μm²Since the workability of the Cu portion at the tip of the shaft portion can be improved, the Cu portion at the tip of the shaft portion can have mechanical properties more suitable for being bent and caulked to be fixed to another member, and can have mechanical properties more suitable for maintaining the fixed state (caulked state). As a result, it is possible to sufficiently suppress the occurrence of cracking when the Cu portion is bent and caulked, and also to sufficiently suppress the occurrence of cracking when an external force such as vibration is applied to the caulked Cu portion.

In the battery terminal according to the first aspect of the present invention, it is more preferable that the cross-sectional area of the Cu crystal grains constituting the Cu portion is 40 μm²The following. Accordingly, the sectional area of Cu crystal grains passing through the Cu portion is 10 μm²Above and 40 μm²Since the workability of the Cu portion at the tip of the shaft portion can be further improved, the Cu portion at the tip of the shaft portion can have mechanical properties sufficiently suitable for being bent and caulked to be fixed to another member, regardless of the shape of the battery terminal, and can also have mechanical properties more suitable for maintaining the fixed state (caulked state). As a result thereofThe occurrence of cracking when the Cu portion is bent and caulked can be sufficiently suppressed, and the occurrence of cracking when an external force such as vibration is applied to the caulked Cu portion can be sufficiently suppressed.

In the battery terminal according to the first aspect, the vickers hardness of the Cu portion is preferably 110HV or more and 125HV or less. Here, if the vickers hardness of the Cu portion of the tip of the shaft portion exceeds 125HV, the workability is too poor, and if the vickers hardness of the Cu portion of the tip of the shaft portion is less than 110HV, the workability is too good. Accordingly, the Cu portion at the tip of the shaft portion has an appropriate vickers hardness, and therefore, the mechanical properties suitable for bending and caulking the Cu portion at the tip of the shaft portion can be obtained, and the mechanical properties suitable for preventing the occurrence of cracking when an external force such as vibration is applied to the caulked Cu portion can be obtained.

A second aspect of the present invention provides a method for manufacturing a battery terminal, including: a step of forming a clad material made of an Al material and a Cu material by bonding an Al plate material made of pure Al or an Al-based alloy and a Cu plate material made of pure Cu or a Cu-based alloy in a state of being sequentially laminated; a step of forming a battery terminal including a shaft portion extending from the Al layer side toward the Cu layer side, a flange portion extending from the side of the shaft portion in a radial direction, and a recess portion surrounded by a wall portion extending to the Cu layer side of a tip of the shaft portion by pressing a clad material so that the Al layer made of the Al material of the clad material and the Cu layer made of the Cu material of the clad material are joined in a state of being sequentially laminated; the step of forming the battery terminal includes: the cross-sectional area of the wall portion constituting the Cu crystal grains of the Cu portion composed of the Cu layer is 10 μm²Above and 100 μm²The clad material is press-worked in the following manner.

A second aspect of the present invention provides a method for manufacturing a terminal for a battery, including: the cross-sectional area of the wall portion constituting the Cu crystal grains of the Cu portion composed of the Cu layer is 10 μm²Above and 100 μm²The clad material is press-worked in the following manner. With this feature, the Cu portion of the wall portion can be formed of the Cu layerSince the Cu portion is press-worked so as to have sufficient hardness, the Cu portion has sufficient workability, and the Cu portion having mechanical properties suitable for being bent and caulked to be fixed to another member can be formed at the tip of the shaft portion, and the Cu portion having mechanical properties suitable for maintaining the fixed state (caulked state) can be formed. Specifically, in order to bend and crimp the Cu portion at the tip end of the shaft portion of the battery terminal and fix the bent Cu portion to another member, the bent Cu portion (particularly, the Cu portion in the base region of the wall portion) is required to have mechanical properties capable of withstanding the bending and crimping. The sectional area of Cu crystal grains is 10 μm²Above and 100 μm²The Cu portion subjected to press working in the following manner can have mechanical properties that can withstand bending and caulking, such as being less likely to break when bent and caulked. In order to maintain a strong fixed state (caulking state) between the battery terminal and another member, mechanical properties for maintaining the fixed state are required for the caulked Cu portion. The sectional area of Cu crystal grains is 10 μm²Above and 100 μm²The Cu portion (particularly, the Cu portion in the base region of the wall portion) which is press-worked in the following manner can have mechanical properties which can withstand the fixed state over time, such as being less likely to break when an external force such as vibration is applied after being fixed to another member by bending and caulking.

In the method for manufacturing a battery terminal according to the second aspect of the present invention, it is preferable that the step of forming the battery terminal includes: so that the cross-sectional area of Cu crystal grains constituting the Cu portion becomes 65 μm²The clad material is press-worked in the following manner. According to such a feature, the cross-sectional area of Cu crystal grains constituting the Cu portion is made to be (10 μm)²Above) 65 μm²Since the clad material can be press-worked in such a manner as described below to improve workability of the Cu portion at the tip of the shaft portion, the Cu portion having mechanical properties more suitable for being fixed to another member by bending and caulking the Cu portion at the tip of the shaft portion can be formed. As a result, the Cu portion can further suppress the occurrence of cracking at the time of bending and caulking, and can sufficiently suppress the occurrence of cracking in the caulked portionThe Cu portion is broken when external force such as vibration is applied.

In the method for manufacturing a battery terminal according to the second aspect of the present invention, it is more preferable that the step of forming the battery terminal includes: so that the cross-sectional area of Cu crystal grains constituting the Cu portion becomes 40 μm²The clad material is press-worked in the following manner. According to such a feature, the cross-sectional area of Cu crystal grains constituting the Cu portion is made 10 μm²Above 40 μm²Since the clad material can be press-worked in the following manner so as to further improve the workability of the Cu portion at the distal end of the shaft portion, the Cu portion having mechanical properties sufficiently suitable for being fixed to another member by bending and caulking the Cu portion at the distal end of the shaft portion can be formed regardless of the shape of the battery terminal. As a result, the Cu portion can sufficiently suppress the occurrence of cracking when bent and swaged, and can sufficiently suppress the occurrence of cracking when an external force such as vibration is applied to the swaged Cu portion.

In the method for manufacturing a terminal for a battery according to the second aspect, the step of forming the terminal for a battery preferably includes the steps of: when the cross-sectional area of the Cu crystal grains constituting the Cu material in the cross-sectional area in the thickness direction of the clad material is S1, and the cross-sectional area of the Cu crystal grains constituting the Cu portion in the cross-sectional area in the axial direction of the shaft portion is S2, the recess portion is formed so that the deformation rate of the Cu crystal grains before and after the press working, which is obtained by (S1-S2)/S1 × 100, is 45% or more and less than 100%. According to such a feature, by forming the concave portion so that the deformation ratio becomes 45% or more and less than 100%, it is possible to form a Cu portion having a smaller cross-sectional area of Cu crystal grains than the Cu material of the clad material before press working. As a result, since the cross-sectional area of the Cu crystal grains constituting the Cu portion is formed small, it is possible to improve mechanical properties such as elongation, suppress the occurrence of cracking when the Cu portion is bent and caulked, and suppress the occurrence of cracking when an external force such as vibration is applied to the caulked Cu portion.

In the method for manufacturing a battery terminal according to the second aspect, the step of forming the battery terminal preferably includes: and forming the recess so that the deformation ratio is 60% or more. With such a feature, in the recess formed so that the deformation ratio becomes 60% or more (less than 100%), the Cu portion having a smaller cross-sectional area of the Cu crystal grain than the Cu material of the clad material before press working can be formed. As a result, the cross-sectional area of the Cu crystal grains constituting the Cu portion is formed smaller, so that mechanical properties such as elongation can be further improved, cracking can be sufficiently suppressed when the Cu portion is bent and caulked, and cracking can be sufficiently suppressed when an external force such as vibration is applied to the caulked Cu portion.

In the method for manufacturing a battery terminal according to the second aspect, the step of forming the clad material preferably includes: and forming the clad material so that the Vickers hardness of the Cu material is 70HV or less at a cross-sectional surface of the clad material in the thickness direction. According to such a feature, since the vickers hardness of the Cu material of the clad material is 70HV or less, the workability at the time of press working can be appropriately improved, the cross-sectional area of the Cu crystal grains constituting the Cu portion after the press working can be set to an appropriate size, and the Cu portion after the press working can be set to an appropriate vickers hardness.

In the method for manufacturing a battery terminal according to the second aspect, the step of forming the battery terminal preferably includes: and a step of press working the clad material so that the Vickers hardness of the Cu portion is 110HV or more and 125HV or less. With such a feature, the following Cu portion can be obtained: the Cu portion after press working has a vickers hardness of 110HV or more and 125HV or less, and thus has mechanical properties suitable for bending and caulking and suitable mechanical properties that are less likely to cause cracking when an external force such as vibration is applied after caulking.

Drawings

Fig. 1 is a perspective view showing a battery pack according to an embodiment of the present invention.

Fig. 2 is a perspective view showing the overall structure of a lithium ion battery according to an embodiment of the present invention.

Fig. 3 is an exploded perspective view showing the overall structure of a lithium ion battery according to an embodiment of the present invention.

Fig. 4 is a cross-sectional view showing a positive electrode terminal of a lithium ion battery according to an embodiment of the present invention.

Fig. 5 is a cross-sectional view showing a state where a positive electrode terminal of a lithium ion battery according to an embodiment of the present invention is caulked to a lid member.

Fig. 6 is a cross-sectional view showing a negative electrode terminal according to an embodiment of the present invention.

Fig. 7 is a cross-sectional view showing another example of the negative electrode terminal according to the embodiment of the present invention.

Fig. 8 is a view (photograph) showing a part of an electron microscope image of a Cu portion of a negative electrode terminal according to an embodiment of the present invention.

Fig. 9 is a cross-sectional view showing a state where the negative electrode terminal of the embodiment of the present invention is caulked to the lid member.

Fig. 10 is a view showing a clad material according to an embodiment of the present invention.

Fig. 11 is a view (photograph) showing a part of an electron microscopic image of a Cu material of a clad material according to an embodiment of the present invention.

Fig. 12 is a schematic view showing a method for producing a clad material according to an embodiment of the present invention.

Fig. 13 is a diagram showing a state before press working according to the embodiment of the present invention.

Fig. 14 is a diagram showing a state after press working according to the embodiment of the present invention.

Fig. 15 is a cross-sectional view showing a state before the negative electrode terminal of the embodiment of the present invention is caulked to the lid member.

Fig. 16 is a cross-sectional view showing a state in which the negative electrode terminal of the embodiment of the present invention is caulked to the lid member.

Fig. 17 is a cross-sectional view showing a state after caulking the negative electrode terminal and the lid member according to the embodiment of the present invention.

Fig. 18 is a cross-sectional view showing a state during laser welding of the negative electrode terminal according to the embodiment of the present invention.

Fig. 19 is a view showing a modification of the negative electrode terminal of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Structure of Battery terminal)

First, a schematic configuration of a battery pack 100 using a battery terminal according to an embodiment of the present invention as a negative electrode terminal 20 will be described with reference to fig. 1 to 11.

The battery pack 100 is a large-sized battery system used in an Electric Vehicle (EV), a Hybrid Electric Vehicle (HEV), a home power storage system, and the like. As shown in fig. 1, the assembled battery 100 is configured by electrically connecting a plurality of lithium ion batteries 1 by a plurality of flat plate-shaped bus bars 101 (shown by broken lines).

In the assembled battery 100, the plurality of lithium ion batteries 1 are arranged so as to be aligned along the short side direction (X direction) of the lithium ion batteries 1 in a plan view. In the assembled battery 100, the lithium ion batteries 1(1a) in which the positive electrode terminal 10 is positioned on one side (Y1 side) in the longitudinal direction (Y direction) orthogonal to the short direction and the negative electrode terminal 20 is positioned on the other side (Y2 side) in the Y direction and the lithium ion batteries 1(1b) in which the positive electrode terminal 10 is positioned on the Y2 side and the negative electrode terminal 20 is positioned on the Y1 side are alternately arranged in the X direction in plan view.

The negative electrode terminal 20 of the predetermined lithium ion battery 1 and the positive electrode terminal 10 of the lithium ion battery 1 adjacent to the predetermined lithium ion battery 1 are joined to one end of the bus bar 101 made of pure Al extending in the X direction by resistance welding. Thereby, the negative electrode terminal 20 of the lithium ion battery 1 is connected to the positive electrode terminal 10 of the adjacent lithium ion battery 1 via the bus bar 101. In this way, the assembled battery 100 in which the plurality of lithium ion batteries 1 are connected in series is configured.

Further, by using the bus bar 101 made of pure Al, the bus bar 101 can be made lighter than when using a bus bar made of pure Cu. Therefore, by using the bus bar 101 made of pure Al, the entire battery pack 100 using the plurality of bus bars 101 can be reduced in weight. Here, pure Al means, for example, aluminum of a1000 series defined in JIS standard. Pure Cu means, for example, C1000 series copper defined in JIS standards such as oxygen-free copper, tough pitch copper, and phosphorus deoxidized copper.

< Structure of lithium Battery >

As shown in fig. 2, the lithium ion battery 1 has a substantially rectangular parallelepiped appearance. The lithium ion battery 1 includes a lid member 2 disposed on one side (Z1 side) in the vertical direction (Z direction) orthogonal to the X direction and the Y direction, and a battery case main body 3 disposed on the other side (Z2 side). The lid member 2 and the battery case body 3 are each made of a Ni-plated steel sheet.

As shown in fig. 3, the cover member 2 is formed in a flat plate shape. The cover member 2 is provided with a pair of

insertion holes

2a and 2b so as to penetrate in the Z direction. The pair of

insertion holes

2a and 2b are formed at a predetermined interval in the Y direction of the lid member 2, and are formed substantially at the center in the X direction of the lid member 2. The positive electrode terminal 10 and the negative electrode terminal 20 are inserted into the pair of

insertion holes

2a and 2b, respectively.

The lithium ion battery 1 includes a power generation element 4 in which a positive electrode 4a, a negative electrode 4b, and a separator 4c are stacked in a roll shape, and an electrolyte solution not shown is stacked. The positive electrode 4a is made of Al foil coated with a positive electrode active material. The negative electrode 4b is made of a Cu foil coated with a negative electrode active material. The separator 4c has a function of insulating the positive electrode 4a and the negative electrode 4 b.

Further, the lithium ion battery 1 includes: a positive electrode current collector 5 for electrically connecting the positive electrode terminal 10 and the positive electrode 4a of the power generating element 4; and a negative electrode current collector 6 for electrically connecting the negative electrode terminal 20 and the negative electrode 4b of the power generating element 4.

The positive electrode current collector 5 is disposed on the Y1 side so as to correspond to the positive electrode terminal 10. In addition, the positive electrode current collector 5 includes: a connecting portion 5a formed with a hole portion 5d into which the positive electrode terminal 10 is inserted; a leg portion 5b extending to the Z2 side; and a connection plate 5c connecting the leg portion 5b and the plurality of positive electrodes 4 a. In addition, the positive electrode current collector 5 is made of pure Al, as with the positive electrode 4 a.

The negative electrode current collector 6 is disposed on the Y2 side so as to correspond to the negative electrode terminal 20. In addition, the negative electrode current collector 6 includes: a connecting portion 6a formed with a hole 6d into which the negative electrode terminal 20 is inserted; a leg portion 6b extending to the Z2 side; and a connection plate 6c connecting the leg portion 6b and the plurality of negative electrodes 4 b. In addition, the negative electrode current collector 6 is composed of pure Cu, as with the negative electrode 4 b.

Further, a sealing member 7 and a sealing member 8 having insulation properties are fitted into the insertion hole 2a and the insertion hole 2b of the cover member 2, respectively. A hole 7a into which the positive electrode terminal 10 is inserted is formed in the sealing member 7. The sealing member 7 is disposed to prevent the upper surface of the lid member 2 on the Z1 side and the inner surface of the insertion hole 2a from coming into contact with the positive electrode terminal 10, and to prevent the lower surface of the lid member 2 on the Z2 side from coming into contact with the positive electrode current collector 5. Further, a hole 8a into which the negative electrode terminal 20 is inserted is formed in the sealing member 8. The sealing member 8 is disposed to suppress the contact between the upper surface of the lid member 2 on the Z1 side and the inner surface of the insertion hole 2b and the negative electrode terminal 20, and to suppress the contact between the lower surface of the lid member 2 on the Z2 side and the negative electrode current collector 6.

(Structure of Positive electrode terminal)

As shown in fig. 3, the positive electrode terminal 10 includes: a cylindrical shaft portion 11 extending in the Z direction; and an annular flange portion 12 formed at an end portion of the shaft portion 11 on the Z1 side and radially extending from the shaft portion 11 in the X direction and the Y direction (X-Y plane direction). The shaft portion 11 is configured to be located substantially at the center of the positive electrode terminal 10 in the X direction and the Y direction.

As shown in fig. 4 and 5, the positive electrode terminal 10 is made of pure Al, as with the positive electrode current collector 5 and the bus bar 101. In addition, the positive electrode terminal 10 has a recess 13 formed in an end portion of the shaft 11 on the Z2 side. The positive electrode terminal 10 is fixed by being joined to the positive electrode current collector 5 (see fig. 3) by laser welding while being caulked to the positive electrode current collector 5 by using the wall portion forming the concave portion 13 in a state where the shaft portion 11 is inserted into the insertion hole 2a of the lid member 2 (the hole portion 7a of the sealing member 7) and the hole portion 5d of the positive electrode current collector 5. The positive electrode terminal 10 having the shaft portion 11, the flange portion 12, and the recess portion 13 is formed by press working an Al plate material, not shown.

(Structure of negative terminal)

As shown in fig. 6 and 7, the negative electrode terminal 20 includes: a cylindrical shaft portion 21 extending in the Z direction; and a flange portion 22 formed at an end portion of the shaft portion 21 on the Z1 side, and formed in an annular shape as viewed from the Z direction, the flange portion radially spreading from the shaft portion 21 in the X direction and the Y direction (X-Y plane direction). The shaft 21 is located substantially at the center of the negative electrode terminal 20 in the X and Y directions. The negative electrode terminal 20 is an example of the "battery terminal" in the claims. The X-Y plane direction is an example of the "radial direction" in the claims.

As shown in fig. 6, the shaft portion 21 of the negative electrode terminal 20 has a T-shape extending from the Al layer 31 side to the Cu layer 32 side, or a cross shape as shown in fig. 7. When the negative electrode terminal 20 has a cross shape, the shaft portion 21 of the negative electrode terminal 20 includes: a first shaft portion 21a extending from the Al layer 31 side to the Cu layer 32 side; and a second shaft portion 21b protruding toward the Al layer 31 side by a protruding length t2 smaller than a length t1 extending to protrude toward the Cu layer 32 side. The bus bar 101 may be connected to the second shaft portion 21b of the negative electrode terminal 20 having a cross shape.

As shown in fig. 6, the shaft portion 21 formed of the Cu layer 32 includes: solid region 25 adjacent to Al layer 31; and a hollow region 26 including the recess 23 and a wall portion 24 surrounding the recess 23. The wall portion 24 is formed to extend from the tip of the solid region 25 of the shaft portion 21 on the Z2 side (Cu layer side). A region from the base (root) of the wall portion 24 in contact with the solid region 25 to the center of the wall portion 24 in the Z2 direction is particularly set as the base region 27.

The concave portion 23 is formed in an annular shape having a circular tube cross section when viewed from the Z2 side. As a result, the Z2 side of the shaft portion 21 in which the recess 23 is formed in a cylindrical shape. That is, the recess 23 is formed in a region surrounded by the cylindrical wall portion 24.

In the negative electrode terminal 20 shown in fig. 6, the vickers hardness of the Cu portion 33 in the wall portion 24 (particularly, the Cu portion 33a of the base region 27) is preferably 110HV or more and 125HV or less. Further, the vickers hardness of the Cu portion 33 (particularly, the Cu portion 33a) is more preferably 114HV to 125HV, and still more preferably 118HV to 125HV, from the viewpoint of preventing cracking when an external force such as vibration is applied to the swaged Cu portion 33. The vickers hardness is determined by pressing a rigid body (indenter) made of diamond into a test object and determining the hardness based on the size of the area of a depression (indentation) formed at that time.

The negative electrode terminal 20 having the vickers hardness of the Cu portion 33 of 110HV to 125HV can have mechanical properties suitable for bending and caulking the Cu portion 33, and also has suitable mechanical properties that are less likely to crack when an external force such as vibration is applied to the caulked Cu portion 33. Specifically, if the Cu portion 33 having the vickers hardness exceeding 125HV is bent and caulked, cracking is likely to occur in the Cu portion. Further, if a Cu portion having a vickers hardness of less than 110HV is bent and caulked, it is likely that cracking occurs when an external force such as vibration is applied to the Cu portion. Therefore, since the Cu portion 33 of the negative electrode terminal 20 has an appropriate vickers hardness of 110HV to 125HV, it is difficult for the Cu portion 33 of the negative electrode terminal 20 to crack due to an external force such as vibration applied during use of the battery pack 100 (lithium ion battery 1).

The vickers hardness is measured in the Cu portion 33 of the wall 24 (preferably, the Cu portion 33a of the base region 27). The base region 27 of the wall portion 24 is a portion that is most likely to be broken when the Cu portion 33 of the wall portion 24 is bent and caulked. If a crack occurs in the base region 27 of the wall portion 24, the negative electrode terminal 20 cannot be connected well to another member (negative electrode collector 6), and therefore the Cu portion 33a of the base region 27 of the wall portion 24 is a particularly important portion. Therefore, the vickers hardness of the Cu portion 33a of the base region 27 of the wall portion 24 is preferably measured. The Cu portion 33a of the base region 27 of the wall portion 24 and the Cu portion 33b of the wall portion 24 other than the base region 27 are both made of the same material as the Cu layer 32, and have the same thickness in the direction in which the flange portion 22 extends (X-Y plane direction). Therefore, it is considered that the vickers hardness of the Cu portion 33a in the base region 27 of the wall portion 24 and the vickers hardness of the Cu portion 33b other than the base region 27 of the wall portion 24 are substantially the same. Therefore, by measuring the vickers hardness of the Cu portion 33a of the base region 27 of the wall portion 24, the vickers hardness of the Cu portion 33 of the wall portion 24 can be obtained.

As shown in fig. 6 and 8, the Cu grains (for example, Cu grains 34) of the Cu portion 33 (particularly, the Cu portion 33a of the base region 27) of the wall portion 24, which is formed of the Cu layer 32Cross-sectional area of 10 μm²Above and 100 μm²The following. If the sectional area of the Cu crystal grains of the Cu portion 33a of the wall portion 24 is 10 μm²Above and 100 μm²Hereinafter, the wall portion 24 may have mechanical properties suitable for being bent and caulked to be fixed to another member (the negative electrode current collector 6), and may have mechanical properties suitable for maintaining the fixed state (the caulked state). That is, if the sectional area of the Cu crystal grains of the Cu portion 33 of the wall portion 24 (particularly the Cu portion 33a of the base region 27) is 10 μm²Above and 100 μm²Hereinafter, it is difficult for cracking to occur when the wall portion 24 is bent and caulked, and it is difficult for cracking to occur when an external force such as vibration is applied after the wall portion 24 is bent and caulked and fixed to another member (the negative electrode current collector 6).

In addition, from the viewpoint of obtaining mechanical characteristics suitable for bending and caulking the wall portion 24 and obtaining mechanical characteristics suitable for maintaining the fixed state (caulking state), the cross-sectional area of the Cu crystal grains (for example, Cu crystal grains 34) of the Cu portion 33 of the wall portion 24 (particularly, the Cu portion 33a of the base region 27) is preferably 10 μm²Above and 65 μm²Hereinafter, more preferably 10 μm²Above and 40 μm²The following. Further, if the area of the Cu crystal grains constituting the Cu portion 33a becomes small, the vickers hardness of the Cu portion 33a tends to become large. If the cross-sectional area of the Cu grains of the Cu portion 33 of the wall portion 24 (particularly the Cu portion 33a of the base region 27) becomes excessively small and less than 10 μm²The Vickers hardness of the Cu portion 33 becomes excessively large and exceeds the upper limit of the Vickers hardness (125 HV). Therefore, the workability of the Cu portion 33 is too poor, and cracking is likely to occur when the wall portion 24 is bent and caulked. In addition, if the sectional area of the Cu crystal grains of the Cu portion 33 of the wall portion 24 (particularly the Cu portion 33a of the base region 27) becomes excessively large and exceeds 100 μm²The Vickers hardness of the Cu portion 33 becomes excessively small and becomes lower than the lower limit of the Vickers hardness (110 HV). Therefore, the Cu portion 33 has excessively low durability, and is likely to be broken when an external force such as vibration is applied to the Cu portion 33 after the wall portion 24 is bent and caulked. Here, the cross-sectional area of the Cu crystal grains (for example, Cu crystal grains 34) of the Cu portion 33 is cut in the direction (Z direction) extending along the shaft portion 21 using an electron microscopeThe cross section of the wall portion 24 is measured. The cross-sectional area of the Cu grains (e.g., Cu grains 34) of the Cu portion 33 is preferably measured in the base region 27 of the wall 24.

The cross-sectional area of the Cu crystal grains of the Cu portion 33 may be a value obtained from an electron microscope image of the Cu portion 33 to be measured using a normal electron microscope and a normal image analysis system attached to the electron microscope. Specifically, for example, under an electron microscope, outline (grain boundary) strengthening processing (for example, processing for drawing the outline of the Cu crystal grains 34) of the Cu crystal grains (for example, the Cu crystal grains 34) constituting the Cu portion 33 is performed, and the area within the outline (grain boundary) is set as the cross-sectional area of the Cu crystal grains (for example, the Cu crystal grains 34). The process of obtaining the cross-sectional area of the Cu crystal grains is performed using an arbitrary plurality of Cu crystal grains in the electron microscope image of the Cu portion 33 of the wall portion 24 (preferably, the Cu portion 33a of the base region 27), and an average value obtained by dividing the total value of the cross-sectional areas of the obtained plurality of Cu crystal grains by the number of Cu crystal grains is obtained as the cross-sectional area (average cross-sectional area) of the Cu crystal grains of the Cu portion 33 in the electron microscope image.

As shown in fig. 6 and 8, it was found that the Cu grains (for example, Cu grains 34) of the Cu portion 33 composed of the Cu layer 32 in the base region 27 of the wall portion 24 are formed into a substantially needle-like form having an extremely large aspect ratio by press working. Therefore, in the present embodiment, the above-described cross-sectional area (average cross-sectional area) is used as an index indicating Cu crystal grains of the Cu portion 33(Cu portion 33a) instead of a general particle diameter (circle-equivalent diameter). Specifically, in the Cu portion 33 of the wall 24 (preferably, the Cu portion 33a of the base region 27), for example, an electron microscope image of a region including the Cu crystal grains 34 is obtained, a cross-sectional area (average cross-sectional area) S2 of the Cu crystal grains in the region is obtained, a cross-sectional area (average cross-sectional area) S1 of the Cu crystal grains constituting the Cu material 320 (see fig. 10) before the press working is used, and a deformation ratio D of the Cu crystal grains before and after the press working of the Cu portion 33(Cu portion 33a) is obtained by the following expression 1.

[ formula 1]

According to the formula 1, the deformation ratio D is 0% when the sectional areas of the Cu crystal grains before and after the press working of the Cu portion 33 are the same. In addition, when the sectional area S2 of the Cu crystal grains of the Cu portion 33 after the press working is smaller than the sectional area S1 of the Cu crystal grains of the Cu material 320 before the press working (see fig. 10) (S2 < S1), the deformation ratio D satisfies 0% < D < 100%. Therefore, the Cu crystal grains after the press working of the Cu portion 33 are deformed smaller as the deformation ratio D is larger than the Cu crystal grains of the Cu material 320 before the press working. Therefore, when the deformation ratio D satisfies 0% < D < 100%, the hardness of the Cu portion 33 after the press working can be increased from the hardness of the Cu material 320 before the press working due to the work hardening by the press working. Further, it is considered that by reducing the sectional area of the Cu crystal grains in the Cu portion 33a of the base region 27 of the wall portion 24, the sectional area of the Cu crystal grains in the Cu portion 33b other than the base region 27 of the wall portion 24 is also reduced similarly. Further, when the vickers hardness of the Cu portion 33 (particularly, the Cu portion 33a of the base region 27) is appropriately higher than the vickers hardness (for example, 70HV or lower) of the Cu material 320 before press working, for example, 110HV or higher and 125HV or lower, it is difficult to cause cracking when the wall portion 24 is bent and caulked. From this viewpoint, the deformation rate D of the Cu grains before and after the press working of the Cu portion 33 (particularly, the Cu portion 33a of the base region 27) is preferably 45% or more, and more preferably 60% or more.

As shown in fig. 9, in a state where the shaft portion 21 is inserted into the insertion hole 2b of the lid member 2 (the hole portion 8a of the sealing member 8) and the hole portion 6d of the negative electrode current collector 6, the wall portion 24 forming the concave portion 23 is bent and caulked to the negative electrode current collector 6, and then joined and fixed to the negative electrode current collector 6 by laser welding. The shape of the concave portion 23 as viewed from the Z2 direction is not particularly limited, and may be, for example, a circular shape, an elliptical shape, a rounded rectangular shape in which the four corners of the rectangular shape are rounded, or the like.

As shown in fig. 10, the negative electrode terminal 20 (see fig. 3) is produced by press working a clad material 300. The clad material 300 is formed using a clad material 300 having a double-layer structure of an Al material 310 and a Cu material 320 by rolling and bonding an Al plate material 131 (see fig. 12) made of pure Al or an Al-based alloy and a Cu plate material 132 (see fig. 12) made of pure Cu or a Cu-based alloy in a state of being laminated in the Z direction. Then, the Al plate material 131 and the Cu plate material 132 which are rolled (clad-rolled) and joined are further subjected to appropriate heat treatment to be atomically (chemically) joined. As a result, the clad member 300 having the two-layer structure of the Al member 310 made of the Al plate member 131 and the Cu member 320 made of the Cu plate member 132 can have a sufficient bonding strength that can withstand the press working with large deformation for producing the negative electrode terminal 20.

The Al material 310 of the clad material 300 corresponds to the Al layer 31 of the negative electrode terminal 20. As the Al material 310 of the clad material 300, that is, pure Al constituting the Al layer 31 of the negative electrode terminal 20, pure Al containing Al of about 99 mass% or more, such as a1050(JIS standard), a1100(JIS standard), a1200(JIS standard), or the like, can be used. Further, as the Al-based alloy, a5000 series (JIS standard) such as a5052 may be used, and a3000 series (JIS standard) may be used.

The Cu material 320 of the clad material 300 corresponds to the Cu layer 32 and the Cu portion 33 of the negative electrode terminal 20. As Cu material 320 of clad material 300, that is, pure Cu constituting Cu layer 32 and Cu portion 33 of negative electrode terminal 20, so-called oxygen-free copper, phosphorus deoxidized copper, tough pitch copper, etc. of C1000 series (JIS standard) may be used, or C1510(JIS standard) to which a small amount of Zr is added for suppressing coarsening of crystals may be used. Further, as the Cu-based alloy, C2000 series (JIS standard) such as C2600 may be used.

Cu crystal grains (for example, Cu crystal grains 340 shown in fig. 11) of Cu material 320 constituting clad material 130 are work-hardened by press working for producing negative electrode terminal 20. Therefore, the vickers hardness of the Cu material 320 constituting the clad material 130 is preferably 70HV or less. In the cross section of the clad material 300 in the thickness direction, if the vickers hardness of the Cu material 320 of the clad material 300 is 70HV or less, the workability at the time of press working is suitably improved, and therefore, the cross-sectional area of the Cu crystal grains (for example, the Cu crystal grains 34) constituting the Cu portion 33 constituted by the Cu layer 32 after the press working can be made to be a suitable size, and the Cu portion 33 can be made to be a suitable hardness, for example, a vickers hardness of 110HV or more and 125HV or less.

As shown in fig. 11, in a cross-sectional surface of clad material 300 along the thickness direction (Z direction), the cross-sectional area of Cu crystal grains (for example, Cu crystal grains 340) constituting Cu material 320 is preferably 40 μm²Above and 750 μm²Hereinafter, more preferably 40 μm²Above and 500 μm²The following. The sectional area of Cu crystal grains constituting the Cu material 320 is preferably 40 μm²Above and 750 μm²Less than, more preferably 40 μm²Above and 500 μm²By press working the clad material 300 so that the deformation rate D is 45% or more and less than 100%, preferably 60% or more, the Cu crystal grains of the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20 after press working as shown in fig. 6 and 7 can be easily formed to 10 μm²Above and 100 μm²Appropriate cross-sectional area (preferably 10 μm) of²Above and 65 μm²Hereinafter, more preferably 10 μm²Above and 40 μm²Below). In addition, the cross-sectional area of Cu crystal grains of the Cu material 320 before press working is less than 40 μm²In the case of (3), the Cu material 320 is difficult to press. In addition, the cross-sectional area of Cu crystal grains of the Cu material 320 before press working exceeds 750 μm²In the case of (3), it is difficult for the Cu material 320 to set the cross-sectional area of the Cu crystal grains of the Cu portion 33 of the wall portion 24 after press working to 100 μm²Hereinafter, it is difficult to increase the hardness of the Cu portion 33. Here, the sectional area of the Cu crystal grains (for example, Cu crystal grains 340) constituting the Cu material 320 can be determined by the above-described method of determining the average sectional area of the Cu crystal grains, as the sectional area of the Cu crystal grains (for example, Cu crystal grains 34) of the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20.

(method of manufacturing negative electrode terminal)

Next, a method for manufacturing the negative electrode terminal 20 of the present embodiment will be described with reference to fig. 12 to 14.

First, as shown in fig. 12, an Al plate material 131 made of pure Al or an Al alloy and a Cu plate material 132 made of pure Cu or a Cu alloy are prepared. The ratio of the thickness of the Al plate member 131 to the thickness of the Cu plate member 132 is substantially the same as the ratio of the thicknesses of the Al layer 31 and the Cu layer 32 in the Z direction in the flange portion 22 constituting the negative electrode terminal 20 (see fig. 6). Here, the thickness of the Al plate material 131 may be the same as that of the Cu plate material 132. The thickness of the Cu plate member 132 may be increased compared to the Al plate member 131 depending on the size (amount of protrusion toward Z2 side, axial diameter) of the shaft portion 21 of the negative electrode terminal 20 after press working, and the like. In order to make the workability of the Cu plate material 132 at the time of clad-rolling close to that of the Al plate material 131, the Cu plate material 132 before clad-rolling may be subjected to temper rolling, softening annealing, or other tempering treatments.

The belt-shaped Al plate material 131 and the belt-shaped Cu plate material 132 are continuously rolled at a predetermined rolling rate by using the rolls R in a state of being laminated in the thickness direction. Thus, a band-shaped clad member 130 having a two-layer structure in which the Al plate member 131 and the Cu plate member 132 are laminated in the thickness direction is produced. At this time, the longitudinal direction of the strip-shaped Al plate material 131 and the strip-shaped Cu plate material 132 becomes the rolling direction. Thus, a band-shaped clad material 130 in which the Al plate material 131 and the Cu plate material 132 are bonded to each other in a state of being laminated in the thickness direction (roll bonding) is produced. Further, the number of passes of the clad layer rolling can be appropriately selected.

Then, after the intermediate rolling or the like is performed as necessary, the clad material 130 is held in an atmosphere of a predetermined atmosphere and a holding temperature at which the Al plate material 131 is not melted for a predetermined time by using the annealing furnace 50, thereby performing diffusion annealing. The holding temperature is, for example, a temperature lower than the melting point of the Al plate material 131. This causes appropriate metal diffusion at the interface where the Al plate material 131 and the Cu plate material 132 are joined, thereby improving the joining strength between the Al plate material 131 and the Cu plate material 132. That is, unlike the Cu-plated Al plate material or the Al-plated Cu plate material, the clad material 130 has a sufficiently higher bonding strength between the Al plate material 131 and the Cu plate material 132 than the plated film. Further, if necessary, finish rolling, shape correction, softening annealing at a holding temperature at which the Al plate material 131 does not melt, and the like may be performed. Then, using the band-shaped clad member 130, a single-sheet clad member 300 having a two-layer structure as shown in fig. 10 suitable for press working to form the negative electrode terminal 20 as shown in fig. 6 and 7, that is, a single-sheet clad member 300 in which an Al material 310 and a Cu material 320 are laminated in the thickness direction and joined to each other, is produced. The single-piece clad material 300 is manufactured, for example, after the clad material 130 is cut.

In the step of forming the clad member 130, when the clad member 300 in a single piece is formed using the band-shaped clad member 130, rolling and diffusion annealing are performed so that the vickers hardness of the Cu member 320 is preferably 70HV or less in a cross section in the thickness direction (Z direction) of the clad member 300 in a single piece, and the cross section of the Cu crystal grains constituting the Cu member 320 is preferably 40 μm²Above and 750 μm²The thickness is more preferably 40 μm or less²Above and 500 μm²Then, finish rolling, shape correction, softening annealing, and the like may be performed as necessary.

Next, the negative electrode terminal 20 shown in fig. 6, for example, is formed using the clad material 300 in a single sheet form in which the Al material 310 and the Cu material 320 are joined in a laminated state along the thickness direction. In the step of forming the negative electrode terminal 20, as shown in fig. 13, a single sheet of clad material 300 is subjected to press working. Specifically, first, the clad member 300 in a single sheet form is disposed in the cavity 41b of the die 41a of the press working machine 41. The cavity 41b of the die 41a has a cavity shape corresponding to the shaft portion 21, the flange portion 22, and the recess portion 23 of the negative electrode terminal 20 shown in fig. 6, for example. Then, as shown in fig. 14, the clad material 300 is subjected to press working by applying pressure from the Z1 side. By this press working, the Cu material 320 of the clad material 300 is moved into the cavity 41b on the Z2 side corresponding to the shaft portion 21.

In the step of press working, the clad material 300 is press-worked so that the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 (particularly, the Cu portion 33a of the base region 27) of the wall portion 24 in the negative electrode terminal 20 after press working becomes 10 μm²Above and 100 μm²Preferably 10 μm or less²Above and 65 μm²The thickness is more preferably 10 μm or less²Above and 40 μm²The following.

In the step of press working, the clad material 300 is preferably press-worked so that the deformation ratio D of the Cu crystal grains before and after press working, which is obtained by (S1-S2)/S1 × 100, becomes 45% or more, more preferably 60% or more, when the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the cross-sectional plane of the clad material 300 in the thickness direction is S1 and the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 in the axial direction (Z direction) of the shaft portion 21 is S2.

In the step of press working, the clad member 300 is preferably press-worked so that the vickers hardness of the Cu portion 33 becomes a preferable vickers hardness of 110HV to 125HV in an axial direction (Z direction) cross section of the shaft portion 21, or so that the vickers hardness becomes a more preferable vickers hardness of 114HV to 125HV, and further becomes a still more preferable vickers hardness of 118HV to 125 HV.

(welding Process of negative electrode terminal)

Next, a welding step of welding the negative electrode terminal 20 to the negative electrode current collector 6 according to the present embodiment will be described with reference to fig. 9 and 15 to 18.

First, as shown in fig. 15, the lid member 2 is prepared in which the sealing member 8 is fitted into the insertion hole 2 b. Then, the connection portion 6a of the negative electrode current collector 6 is brought into contact with the surface of the sealing member 8 on the Z2 side. In this state, the fixing member 103a of the caulking jig 103 is brought into contact with and fixed to the surface of the negative electrode current collector 6 on the Z2 side. In this state, the rod-like member 103b of the caulking jig 103 is inserted into the insertion hole 2b (the hole 8a of the seal member 8) from the Z2 side. Then, the Z1-side end of the inserted rod-like member 103b is fitted into the concave portion 23 of the negative electrode terminal 20.

Then, the negative terminal 20 is pressed from the Z1 side to the Z2 side by the pressing member 103c of the caulking jig 103. Thereby, as shown in fig. 16, the negative electrode terminal 20 moves toward the Z2 side together with the rod 103 b. Then, the end of the negative electrode terminal 20 moved to the Z2 side of the wall portion 24 is positioned on the Z2 side of the insertion hole 2b by the pressing force of the pressing member 103 c. Next, the negative electrode terminal 20 moves the Cu portion 33 of the cylindrical wall portion 24 toward the Z2 side while deforming along the outer peripheral surface of the rod 103 b. Next, the negative electrode terminal 20 moves the Cu portion 33 of the cylindrical wall portion 24 to the Z2 side while further deforming along the concave surface of the fixing member 103a of the caulking jig 103 on the Z1 side. Then, when the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20 is bent and deformed as shown in fig. 17, the movement of the rod-like member 103b is stopped. As a result, the wall portion 24 of the negative electrode terminal 20 is bent so as to have a semicircular cross section as shown in fig. 17. Thus, the negative electrode terminal 20 is crimped to the negative electrode current collector 6 by the Cu portion 33 of the wall portion 24 bent radially in the X-Y plane direction.

Then, as shown in fig. 18, the negative electrode terminal 20 and the negative electrode current collector 6 in a caulked state are welded by laser welding. Specifically, the portion of the negative electrode terminal 20 on the tip side of the wall portion 24 bent radially in the X-Y plane direction is welded and joined in a ring shape to the connecting portion 6a of the negative electrode current collector 6, whereby the tip of the wall portion 24 on the Z2 side of the negative electrode terminal 20 on the side joined to the negative electrode current collector 6 of the lithium ion battery 1 is joined to the negative electrode current collector 6 as shown in fig. 9.

< Effect of the present embodiment >

In the present embodiment, the following effects can be obtained.

In the present embodiment, the negative electrode terminal 20 includes: a shaft portion 21 extending from the Al layer 31 side to the Cu layer 32 side, a flange portion 22 extending from the side of the shaft portion 21 in the radial direction, and a recess 23 surrounded by a wall portion 24 extending from the tip of the shaft portion 21 on the Cu layer 32 side, wherein the cross-sectional area of Cu crystal grains of the wall portion 24 constituting a Cu portion 33 constituted by the Cu layer 32 is 10 [ mu ] m in an axial cross-sectional surface of the shaft portion 21²Above and 100 μm²The following. Thus, in the axial cross-sectional surface of the shaft 21, the cross-sectional area of the Cu crystal grains of the wall 24 constituting the Cu portion 33 composed of the Cu layer 32 is 10 μm²Above and 100 μm²Hereinafter, the Cu portion 33 at the tip of the shaft portion 21 has an appropriate vickers hardness, and thus can have sufficient workability. Therefore, the mechanical properties suitable for being fixed to another member by bending and caulking the Cu portion 33(Cu portion 33b) at the tip end of the shaft portion 21 can be obtained, and the mechanical properties suitable for maintaining the fixed state (caulked state) can be obtained. Specifically, in order to be fixed to another member by bending and caulking the Cu portion 33(Cu portion 33b) at the tip end of the shaft portion of the negative electrode terminal 20, the bent Cu portion 33(Cu portion 33b) is required to have mechanical properties capable of withstanding bending and caulking. The cross-sectional area of Cu crystal grains is 10 μm²Above and 100 μm²The following Cu moiety33 can have mechanical characteristics that can withstand bending and caulking, such as being less likely to break when bent and caulked. In order to maintain a strong fixed state (caulking state) between the negative electrode terminal 20 and another member, the mechanical characteristics of the caulked Cu portion 33(Cu portion 33b) are required to maintain the fixed state. The cross-sectional area of Cu crystal grains is 10 μm²Above and 100 μm²The following Cu portion 33(Cu portion 33b) can have mechanical properties that can withstand the fixed state over time, such as being less likely to break when an external force such as vibration is applied after being fixed to another member by bending and caulking.

In the present embodiment, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 is 65 μm²The following. Thus, the sectional area of the Cu crystal grains passing through the Cu portion 33 is (10 μm)²Above) 65 μm²Since the workability of the Cu portion 33(Cu portion 33b) at the distal end of the shaft portion 21 can be improved as described below, the mechanical properties more suitable for bending and caulking the Cu portion 33 at the distal end of the shaft portion 21 to fix it to another member can be obtained, and the mechanical properties sufficiently suitable for maintaining the fixed state (caulked state) can be obtained. As a result, it is possible to sufficiently suppress the occurrence of cracking when the Cu portion 33(Cu portion 33b) is bent and caulked, and also possible to sufficiently suppress the occurrence of cracking when an external force such as vibration is applied to the caulked Cu portion 33(Cu portion 33 b). In the present embodiment, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 is 40 μm²The following (10 μm)²Above). Thus, the sectional area of the Cu crystal grains passing through the Cu portion 33 is 40 μm²Since the workability of the Cu portion 33(Cu portion 33b) at the tip of the shaft portion 21 can be further improved, the Cu portion 33(Cu portion 33b) at the tip of the shaft portion 21 can have mechanical properties more suitable for being bent and caulked to be fixed to another member regardless of the shape of the negative electrode terminal 20, and can have mechanical properties more suitable for maintaining the fixed state (caulked state). As a result, it is possible to sufficiently suppress the occurrence of cracking when the Cu portion 33 is bent and caulked, and also to sufficiently suppress the occurrence of cracking when an external force such as vibration is applied to the caulked Cu portion 33(Cu portion 33 b).

In the present embodiment, the vickers hardness of the Cu portion 33 is 110HV to 125 HV. Accordingly, the Cu portion 33 at the distal end of the shaft portion 21 has an appropriate vickers hardness, and therefore, the mechanical properties suitable for bending and caulking the Cu portion 33 at the distal end of the shaft portion 21 can be obtained, and the mechanical properties suitable for preventing the occurrence of cracking when an external force such as vibration is applied to the caulked Cu portion 33 can be obtained.

The method for manufacturing the negative electrode terminal 20 of the present embodiment includes: in the axial cross-section of the shaft 21, the cross-sectional area of Cu crystal grains constituting the Cu portion 33 (particularly the Cu portion 33a of the base region 27) of the wall 24 consisting of the Cu layer 32 is set to 10 μm²Above and 100 μm²The clad member 300 is press-worked in the following manner. Accordingly, since the Cu portion 33 of the wall portion 24 can be press-worked so as to have sufficient hardness, the Cu portion 33 has sufficient workability, the Cu portion 33 having mechanical properties suitable for being fixed to another member by bending and caulking can be formed at the distal end of the shaft portion 21, and the Cu portion 33 having mechanical properties suitable for maintaining the fixed state (caulking state) can be formed. Specifically, in order to bend and crimp the Cu portion 33 at the tip end of the shaft portion 21 of the negative electrode terminal 20 and fix the bent Cu portion 33 to another member, mechanical properties that can withstand bending and crimping are required for the bent Cu portion 33 (particularly, the Cu portion 33a of the base region 27 of the wall portion 24). The sectional area of Cu crystal grains is 10 μm²Above and 100 μm²The Cu portion 33 subjected to press working in the following manner can have mechanical characteristics that can withstand bending and caulking, such as being less likely to break when bent and caulked. In addition, in order to maintain a strong fixed state (caulking state) between the negative electrode terminal 20 and another member, mechanical characteristics for maintaining the fixed state are required for the caulked Cu portion 33. The sectional area of Cu crystal grains is 10 μm²Above and 100 μm²The Cu portion 33 (particularly, the Cu portion 33a of the base region 27 of the wall portion 24) which is press-worked in the following manner can have mechanical properties which are less likely to cause cracking when an external force such as vibration is applied after being fixed to another member by bending and caulking, and which can withstand the fixed state over time.

This implementationIn the embodiment, the step of forming the negative electrode terminal 20 includes: so that the sectional area of Cu crystal grains constituting the Cu part 33 becomes 40 μm²The clad member 300 is press-worked in the following manner. Thereby, the cross-sectional area of the Cu crystal grains constituting the Cu part 33 is made (10 μm)²Above) 65 μm²Since the clad member 300 can be press-worked in the following manner to improve workability of the Cu portion 33 at the distal end of the shaft portion 21, the Cu portion 33 having mechanical properties more suitable for being bent and caulked to be fixed to another member at the distal end of the shaft portion 21 can be formed. As a result, the Cu portion 33 can further suppress the occurrence of cracking when bent and swaged, and can sufficiently suppress the occurrence of cracking when an external force such as vibration is applied to the swaged Cu portion 33.

In the present embodiment, the step of forming the negative electrode terminal 20 includes: so that the sectional area of Cu crystal grains constituting the Cu part 33 becomes 40 μm²The clad member 300 is press-worked in the following manner. Thereby, the cross-sectional area of the Cu crystal grains constituting the Cu part 33 is made (10 μm)²Above) 40 μm²Since the clad member 300 can be press-worked in the following manner to further improve the workability of the Cu portion 33 at the distal end of the shaft portion 21, the Cu portion 33 having mechanical properties more suitable for being fixed to another member by bending and caulking the Cu portion 33 at the distal end of the shaft portion 21 can be formed. As a result, the Cu portion 33 can sufficiently suppress the occurrence of cracking when bent and swaged, and can sufficiently suppress the occurrence of cracking when an external force such as vibration is applied to the swaged Cu portion 33.

In the present embodiment, the step of forming the negative electrode terminal 20 includes the steps of: when the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the cross-sectional plane in the thickness direction of the clad material 300 is S1, and the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 in the axial cross-sectional plane of the shaft portion 21 is S2, the recess 23 is formed so that the deformation rate of the Cu crystal grains before and after press working, which is obtained by (S1-S2)/S1 × 100, is 45% or more and less than 100%. Thus, by forming the concave portion 23 so that the deformation ratio becomes 45% or more and less than 100%, the Cu portion 33 having a smaller cross-sectional area of Cu crystal grains than the Cu material 320 of the clad material 300 before press working can be formed. As a result, since the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 is formed small, it is possible to improve mechanical properties such as elongation, suppress the occurrence of cracking when the Cu portion 33 is bent and caulked, and suppress the occurrence of cracking when an external force such as vibration is applied to the caulked Cu portion 33.

In the present embodiment, the step of forming the negative electrode terminal 20 includes a step of forming the concave portion 23 so that the deformation ratio becomes 60% or more (less than 100%). Thus, in the recess 23 formed so that the deformation ratio becomes 60% or more (less than 100%), the Cu portion 33 having a smaller cross-sectional area of Cu crystal grains than the Cu material 320 of the clad material 300 before press working can be formed. As a result, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 is formed smaller, so that mechanical properties such as elongation can be further improved, cracking can be sufficiently suppressed when the Cu portion 33 is bent and caulked, and cracking can be sufficiently suppressed when an external force such as vibration is applied to the caulked Cu portion 33.

In the present embodiment, the step of forming the clad material 300 includes: and forming the clad material 300 so that the Vickers hardness of the Cu material 320 is 70HV or less in a cross-sectional surface of the clad material 300 in the thickness direction (Z direction). Accordingly, since the vickers hardness of the Cu material 320 of the clad material 300 is 70HV or less, the workability at the time of press working can be appropriately improved, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 after press working can be set to an appropriate size, and the Cu portion 33 after press working can be set to an appropriate vickers hardness.

In the present embodiment, the step of forming the negative electrode terminal 20 includes: and a step of press working the clad material 300 so that the Vickers hardness of the Cu portion 33 is 110HV or more and 125HV or less. Thus, the Cu portion 33 has mechanical properties suitable for bending and caulking, and suitable mechanical properties that are less likely to cause cracking when an external force such as vibration is applied after caulking.

[ example 1]

Cladding material 300 of examples (nos. 1 to 20) was produced in the same manner as in the production method of the above embodiment. At this time, as shown in fig. 12, the clad material 130 is produced by performing clad rolling and diffusion annealing, and the clad material 130 is produced so that the clad material 300 having the two-layer structure as shown in fig. 10 has a predetermined shape suitable for the negative electrode terminal 20 after press working.

The clad material 300 thus produced was measured for the cross-sectional area of the Cu crystal grains constituting the Cu material 320 at the cross-sectional plane in the thickness direction (Z direction) of the clad material 300 using the area measurement function attached to a digital microscope (VHX-5000 manufactured by KEYENCE, K.K.). The measurement results are shown in table 1.

Then, the vickers hardness of the Cu material 320 was measured at a cross-section in the thickness direction (Z direction) of a plurality of clad materials 300 arbitrarily selected from the produced clad materials 300, and as a result, for example, 58HV, 60HV, 67HV, and the like were obtained, and the range was from 58HV to 67HV, and the average value thereof was 61.7 HV. The vickers hardness was measured according to JIS Z2244: 2009 (load 0.49N).

Next, using the clad member 300 thus produced, press working as shown in fig. 13 and 14 was performed in the same manner as in the present embodiment, to produce negative electrode terminals 20 of examples (nos. 1 to 20). The press working of the clad material 300 was adjusted so that the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 composed of the Cu layer 32 of the wall portion 24 of the negative electrode terminal 20 was reduced to 10 μm²Above and 100 μm²Hereinafter, it is preferably collected to 10 μm²Above and 65 μm²More preferably, it is less than 10 μm²Above and 40 μm²The following ranges. As a result, as shown in Table 1, the sectional area of the Cu crystal grains in the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20 was reduced to 10 μm²Above and 65 μm²The following preferred ranges.

Then, nos. 21 to 30 were arbitrarily selected from the negative electrode terminals 20 of examples (nos. 1 to 20), and vickers hardness of the Cu member 320 was measured on the cross-sectional surface in the axial direction (Z direction) of the shaft portion 21 of the negative electrode terminals 20 of nos. 21 to 30. The vickers hardness was measured according to JIS Z2244: 2009 (load 0.49N). The measurement results are shown in table 2.

[ Table 1]

[ Table 2]

As shown in Table 1, in the case of No.1, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 194 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 20 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 90%.

In the case of No.2, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 117 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 62 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 47%.

In the case of No.3, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 495 μm². In addition, the cross-sectional area of the Cu crystal grains of the Cu portion 33 in the negative electrode terminal 20 after the press working was about 16 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 97%.

In the case of No.4, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 331 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 36 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 89%.

In the case of No.5, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 172 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 18 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 89%.

In the case of No.6, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 186. mu.m². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 25 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 86%.

In the case of No.7, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 244 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 13 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 95%.

In the case of No.8, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 323 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 45 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 86%.

In the case of No.9, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 65 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 20 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 69%.

In the case of No.10, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 59 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 23 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 61%.

In the case of No.11, before the press workingIn clad material 300, the cross-sectional area of Cu grains constituting Cu material 320 is about 286 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 37 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 87%.

In the case of No.12, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 729 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 31 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 96%.

In the case of No.13, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 218 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 25 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 88%.

In the case of No.14, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 697 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 26 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 96%.

In the case of No.15, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 132 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 22 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 83%.

In the case of No.16, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 162 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 53 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working is set toIs about 67%.

In the case of No.17, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 414 μm². In the negative electrode terminal 20 after press working, the sectional area of the Cu crystal grain constituting the Cu portion 33 is minimized to about 11 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 97%.

In the case of No.18, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 173 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 34 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 80%.

In the case of No.19, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 183 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 25 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 86%.

In the case of No.20, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 in the clad material 300 before press working was about 173 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 59 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 66%.

As shown in table 2, in each of nos. 21 and 22, the vickers hardness of the Cu portion 33 in the negative electrode terminal 20 after press working was about 123 HV.

In each of nos. 23 and 24, the vickers hardness of the Cu portion 33 in the negative electrode terminal 20 after press working was about 122 HV.

In the case of nos. 25, 26, 27, 28, 29 and 30, the vickers hardnesses of the Cu portions 33 in the negative electrode terminal 20 after press working were about 118HV, about 119HV, about 121HV, about 120HV, about 125HV and about 118HV, respectively, in this order.

[ example 2]

Cladding material 300 of example 2 (nos. 31 to 60) was produced in the same manner as in example 1. Then, using the clad material 300 thus produced, the negative electrode terminal 20 of example 2 (nos. 31 to 60) was produced in the same manner as in example 1. The press working of the clad material 300 was adjusted in the same manner as in example 1 so that the sectional area of the Cu crystal grains constituting the Cu portion 33 made of the Cu layer 32 of the wall portion 24 of the negative electrode terminal 20 was reduced to 10 μm²Above and 100 μm²Hereinafter, it is preferably collected to 10 μm²Above and 65 μm²More preferably, it is less than 10 μm²Above and 40 μm²The following ranges. As a result, as shown in Table 3, the sectional area of the Cu crystal grains in the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20 was reduced to 10 μm²Above and 100 μm²The following appropriate ranges. In example 2, a negative electrode terminal 20 different from that of example 1 was produced using a clad material 300 different from that of example 1. The volume ratio of the entire clad material 300 of example 2 to that of example 1 was about 2.5 times, and the volume ratio of the Cu material 320 was about 2.5 times. In the negative electrode terminal 20 of example 2, the volume ratio of the portion (portion indicated by t1 in fig. 7) of the shaft portion 21 on the Z2 side with respect to the flange portion 22 was about 4.5 times, the volume ratio of the other portions was about 3 times, the volume ratio of the wall portion 24 was about 6 times, and the thickness (wall thickness) of the wall portion 24 was about 3 times, with respect to example 1.

As in the case of example 1, the cross-sectional area of the Cu grains constituting the Cu material 320 was measured at the cross-sectional surface of the clad material 300 in the thickness direction (Z direction). The measurement results are shown in table 3.

Then, the vickers hardness of the Cu material 320 was measured on the cross-sectional surface in the thickness direction (Z direction) of a plurality of clad materials 300 arbitrarily selected from the produced clad materials 300 in the same manner as in the case of example 1, and as a result, the vickers hardness was, for example, 63HV, 64HV, 68HV, and the like, and the range was 63HV to 68HV, and the average value thereof was 65.0 HV.

In the negative electrode terminal 20 thus produced, as in the case of example 1, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33(Cu portion 33a) was measured at the cross-sectional surface of the shaft portion 21 of the negative electrode terminal 20 in the axial direction (Z direction). The measurement results are shown in table 3.

Then, nos. 61 to 70 were arbitrarily selected from the negative electrode terminals 20 of nos. 31 to 60, and the vickers hardness of the Cu material 320 was measured on the cross-sectional surface in the axial direction (Z direction) of the shaft portion 21 of the negative electrode terminals 20 of nos. 61 to 70. The measurement results are shown in table 4.

[ Table 3]

[ Table 4]

As shown in Table 3, in the case of No.31, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 322 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 52 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 84%.

In the case of No.32, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 175 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 47 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 73%.

In the case of No.33, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 230 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 42 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 82%.

In the case of No.34, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 249 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 57 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 77%.

In the case of No.35, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 263 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 61 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 77%.

In the case of No.36, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 181 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 56 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 69%.

In the case of No.37, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 101 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 29 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 71%.

In the case of No.38, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 150 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 40 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 73%.

In the case of No.39, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 194 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 46 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 76%.

In the case of No.40, the clad before press workingThe cross-sectional area of the Cu grains of the Cu material 320 in the material 300 is about 402 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 92 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 77%.

In the case of No.41, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 280 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 63 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 78%.

In the case of No.42, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 321 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 52 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 84%.

In the case of No.43, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 183 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 31 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 83%.

In the case of No.44, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 221 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 50 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 77%.

In the case of No.45, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 287 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 is about 94 μm at most². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 67%.

In the case of No.46, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 151 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 38 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 75%.

In the case of No.47, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 438 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 47 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 89%.

In the case of No.48, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 201 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 66 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 67%.

In the case of No.49, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 105 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 24 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 77%.

In the case of No.50, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 444 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 72 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 84%.

In the case of No.51, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 47 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 14 μm². Then, Cu crystal grains before and after press workingThe deformation ratio D of the sectional area was about 71%.

In the case of No.52, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 456 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 68 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 85%.

In the case of No.53, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 331 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 39 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 88%.

In the case of No.54, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 101 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 21 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 79%.

In the case of No.55, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 342 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 49 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 86%.

In the case of No.56, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 280 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 28 μm². Then, the deformation ratio D of the sectional area of the Cu crystal grains before and after the press working was about 90%.

In the case of No.57, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 245 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 54 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 78%.

In the case of No.58, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 161 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 22 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 86%.

In the case of No.59, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 287 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 36 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 87%.

In the case of No.60, the cross-sectional area of the Cu grains of the Cu material 320 in the clad material 300 before press working was about 207 μm². In the negative electrode terminal 20 after press working, the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was about 34 μm². Then, the deformation ratio D of the cross-sectional area of the Cu crystal grains before and after the press working was about 83%.

As shown in table 4, in each of nos. 61 and 67, the vickers hardness of the Cu portion 33 in the negative electrode terminal 20 after press working was about 124 HV.

In each of nos. 62, 66 and 68, the vickers hardness of the Cu portion 33 in the negative electrode terminal 20 after press working was about 121 HV.

In the case of nos. 63, 64, 65, 69, and 70, the vickers hardnesses of the Cu portions 33 in the negative electrode terminal 20 after press working were about 119HV, about 123HV, about 122HV, about 118HV, and about 120HV, respectively, in this order.

When the clad materials 300 (nos. 1 to 20 and 31 to 60) of the above examples 1 and 2 were press-worked to prepare the negative electrode terminal 20, the sectional area of the Cu crystal grains constituting the Cu portion 33 composed of the Cu layer 32 of the wall portion 24 of the negative electrode terminal 20 was confirmed. Then, it was confirmed that the wall portion 24 of the negative electrode terminal 20 (Nos. 1 to 20) of example 1 constituted CuThe cross-sectional area of Cu crystal grains of the portion 33 was 10 μm²Above and 65 μm²The following more appropriate ranges. In addition, it was confirmed that the sectional area of the Cu crystal grains constituting the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20 (Nos. 31 to 60) of example 2 was 10 μm²Above and 100 μm²The following appropriate ranges. In addition, it was confirmed that no crack was generated in the wall portion 24 in particular in the negative electrode terminals 20 (nos. 1 to 20 and nos. 31 to 60) of examples 1 and 2. In particular, the cross-sectional area of Cu crystal grains of No.40 clad material was 94 μm²The crystal grains are also largest in the examples, and the vickers hardness is 118HV, and the steel sheet has sufficient workability and sufficient mechanical strength. In addition, the cross-sectional area of Cu crystal grains of the clad material of No.41 was 63 μm²Since the vickers hardness is 122HV, the workability is further improved and the mechanical strength is sufficient. In addition, the Cu crystal grains of No.29 clad material had a cross-sectional area of 11 μm²The cross-sectional area is the smallest among the examples, but the Vickers hardness is the largest 125HV, and the steel has sufficient workability and has the best mechanical strength.

The inventors of the present application have found, based on the results of examples 1 and 2, that the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 made of the Cu layer 32 of the wall portion 24 of the negative electrode terminal 20 is reduced to 10 μm by press working the clad material 300²Above and 100 μm²The negative electrode terminal 20 shown in fig. 6 can be produced without cracking from the clad member 300 shown in fig. 10.

The inventors of the present application also found that the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 was reduced to 10 μm by press working the clad material 300 based on the results obtained from the results of examples 1 and 2 and the results in consideration of the error (variation) in vickers hardness that may occur during production²Above and 100 μm²Hereinafter, the vickers hardness may be set to 110HV or more and 125HV or less. The present inventors also found that the Cu portion 33 is formed by press working the clad material 300, based on the results obtained from the results of examples 1 and 2 and the results obtained from the production of the clad material in consideration of the error (variation) in vickers hardness that may occur during productionThe cross-sectional area of the Cu crystal grains is contained in 10 μm²Above and 65 μm²Hereinafter, the vickers hardness may be set to 115HV or more and 125HV or less. The inventors of the present invention have found that the sectional area of the Cu crystal grains constituting the Cu portion 33 is adjusted to 10 μm²Above and 40 μm²The Vickers hardness is 118HV or more and 125HV or less.

In addition, the present inventors have found from the results of No.67 and the results of No.69 that the difference between the sectional areas of the Cu crystal grains constituting the Cu part 33 is about 60 μm²In the case of (3), the difference in Vickers hardness was also within the range of 6 HV. Further, the present inventors have found, based on the results, that the cross-sectional area of Cu crystal grains is 94 μm from No.69²Increase to 100 μm²In the case of (2), the Vickers hardness is not less than 110 HV. Then, it was found that the sectional area of Cu crystal grains constituting Cu portion 33 of Cu layer 32 of wall portion 24 was 10 μm by using cladding material 300 as shown in FIG. 10²Above and 100 μm²The negative electrode terminal 20 manufactured by press working in the following manner can have the Cu portion 33 having an appropriate hardness of 110HV to 125HV inclusive in vickers hardness.

The inventors of the present application have found that the sectional area of the Cu crystal grains of the wall portion 24 constituting the Cu portion 33 composed of the Cu layer 32 is 10 μm²Above and 100 μm²The negative electrode terminal 20 described below can be produced by using the clad material 300 as shown in fig. 10, and performing press working on the Cu crystal grains (cross-sectional area S1) constituting the Cu material 320 of the clad material 300 so that the deformation ratio D of the cross-sectional area of the Cu crystal grains is 45% or more and less than 100%.

The inventors of the present application have found that the sectional area of the Cu crystal grains of the wall portion 24 constituting the Cu portion 33 composed of the Cu layer 32 is 10 μm²Above and 100 μm²The negative electrode terminal 20 described below can be manufactured by press working using a clad material 300 having a vickers hardness of a Cu material 320 of 70HV or less, as shown in fig. 10, at a deformation ratio D of 45% or more and less than 100%, so that the vickers hardness of a Cu portion 33 of the wall portion 24, which is formed of the Cu layer 32, is 110HV or more and 125HV or less.

Next, using the negative electrode terminals 20 (nos. 1 to 20 and 31 to 60) produced in examples 1 and 2, the wall portion 24 was bent, caulked, and laser-welded as shown in fig. 15 to 18 to be in a fixed state (caulked state) in the same manner as in the present embodiment. At this time, it was confirmed that no crack occurred in the negative electrode terminal 20 (particularly, in the base region 27 of the wall portion 24). From the results, the inventors of the present application have found that, by using a clad material 300 as shown in fig. 10, the sectional area of Cu crystal grains constituting a Cu portion 33 composed of a Cu layer 32 of a wall portion 24 is 10 μm²Above and 100 μm²The negative electrode terminal 20 produced by press working in the following manner is composed of Cu crystal grains in which the Cu portion 33 at the tip of the shaft portion 21 has an appropriate cross-sectional area, and therefore can have mechanical properties suitable for being fixed to another member by bending and caulking the Cu portion 33 at the tip of the shaft portion 21.

Next, after the negative electrode terminals 20 (nos. 1 to 20 and 31 to 60) of examples 1 and 2 were set to the above-described fixed state (caulking state), the application of appropriate vibration was continued on the assumption of the in-vehicle use. At this time, it was confirmed that no crack occurred in the negative electrode terminal 20 (particularly, in the base region 27 of the wall portion 24). From the results, the inventors of the present application have found that, by using a clad material 300 as shown in fig. 10, the sectional area of Cu crystal grains constituting a Cu portion 33 composed of a Cu layer 32 of a wall portion 24 is 10 μm²Above and 100 μm²In the negative electrode terminal 20 produced by press working in the following manner, since the Cu portion 33 at the tip of the shaft portion 21 is made of Cu crystal grains having an appropriate cross-sectional area, it can have mechanical properties suitable for being subjected to and maintained over time in a fixed state (caulking state) in which the Cu portion 33 at the tip of the shaft portion 21 is bent and caulked.

[ modified examples ]

Further, it should be considered that the embodiments and examples disclosed herein are examples in all points and are not restrictive examples. The scope of the present invention is shown by the claims rather than the description of the above embodiments and examples, and includes all modifications (variations) within the meaning and scope equivalent to the claims.

For example, in the present embodiment, an example of a clad material having a two-layer structure in which an Al layer and a Cu layer are laminated and bonded is shown, but the present invention is not limited to this. In the present invention, for example, a clad material having a 3-layer structure in which an Al layer, a Cu layer, and a Ni layer are laminated in this order and joined may be used.

In addition, although the present embodiment shows an example of a clad material having a two-layer structure in which an Al layer and a Cu layer are laminated and bonded, the present invention is not limited to this. The utility model discloses in, also can be more than 3 layer structures. In this case, for example, a clad material having a 4-layer structure may be used, or a clad material having a 4-layer structure in which an Al layer, an Ni layer, a Cu layer, and an Ni layer are laminated in this order and bonded may be used. In the case of a 3-layer structure or more, if the cross-sectional area of crystal grains of the Cu portion composed of the Cu layer is 10 μm²Above and 100 μm²Hereinafter, the clad material has sufficient mechanical strength.

In the present embodiment, the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20 as the battery terminal is bent, but the present invention is not limited thereto. In the present invention, for example, as shown in fig. 19, the Cu portion of the wall portion may be subjected to an expanding process to form a battery terminal.

In the present embodiment, an example in which vickers hardness or the like is measured in the Cu portion 33(Cu portion 33a) of the base region 27 of the wall portion 24 is shown, but the present invention is not limited to this. In the present invention, for example, vickers hardness or the like may be measured at the tip end portion of the Cu portion 33 of the wall portion 24 on the Z2 side.

In the present embodiment, the concave portion 23 is formed in an annular shape having a circular tube cross section when viewed from the Z2 side, but the present invention is not limited to this. In the present invention, the concave portion may not be circular, for example, may be rectangular, when viewed from the direction Z2.

In the present embodiment, the flange portion 12 has an annular shape when viewed in the Z direction, but the present invention is not limited to this. In the present invention, the flange portion may not be circular, for example, may be rectangular, as viewed in the Z direction.

In the present embodiment, the example in which the battery terminal is used as the negative electrode terminal 20 of the battery pack 100 is described, but the present invention is not limited to this. In the present invention, the terminal for a battery may be used as the negative terminal of the cell.

Claims

1. A terminal for a battery, characterized in that:

the battery terminal is composed of a clad material,

the clad material is formed by bonding an Al layer made of pure Al or an Al-based alloy and a Cu layer made of pure Cu or a Cu-based alloy in a state of being sequentially laminated,

the battery terminal is provided with: a shaft portion extending from the Al layer side toward the Cu layer side; a flange portion extending from a side of the shaft portion in a radial direction; and a recess surrounded by a wall portion further extending from a tip of the shaft portion on the Cu layer side,

in an axial cross-sectional surface of the shaft portion, a cross-sectional area of a Cu crystal grain of the wall portion constituting a Cu portion constituted by the Cu layer is 10 μm²Above and 100 μm²The following.

2. The battery terminal according to claim 1, wherein:

the cross-sectional area of Cu crystal grains constituting the Cu portion was 65 μm²The following.

3. The battery terminal according to claim 2, wherein:

the cross-sectional area of Cu crystal grains constituting the Cu portion was 40 μm²The following.

4. The battery terminal according to claim 1, wherein:

the Vickers hardness of the Cu portion is 110HV or more and 125HV or less.