JP7336025B2 - BATTERY TERMINAL AND METHOD FOR MANUFACTURING BATTERY TERMINAL - Google Patents

Description

TECHNICAL FIELD The present invention relates to a battery terminal suitable for, for example, a lithium ion battery and a method for manufacturing the battery terminal, and particularly to a battery comprising 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. The present invention relates to a method for manufacturing a battery terminal and a battery terminal.

Conventionally, a battery terminal is known that includes a first metal layer made of an Al-based alloy and a second metal layer made of a Cu-based alloy (see, for example, Patent Document 1).

The battery terminal disclosed in Japanese Patent No. 6014808 has a shaft portion and a collar portion that extends radially from the shaft portion. Further, in Japanese Patent No. 6014808, the battery terminal is fixed to another member by bending and crimping the Cu portion composed of the Cu layer at the tip of the shaft portion.

Patent No. 6014808

Although not described in Japanese Patent No. 6014808, in order to fix the Cu portion at the tip of the shaft portion of the battery terminal to another member by bending and crimping, the Cu portion to be bent must be bent and crimped. Enduring mechanical properties are required. In addition, in order to maintain a firm fixed state (crimped state) between the battery terminal and other members, the crimped Cu portion is required to have mechanical properties to withstand the fixed state over time. Accordingly, the inventors of the present application conducted extensive research and found that if the workability of the Cu portion is excessively poor, cracks will occur in the Cu portion when the Cu portion is bent and crimped. In addition, if the workability of the Cu portion is excessively good, after the Cu portion at the tip of the shaft portion of the battery terminal is bent and crimped to fix it to another member, an external force such as vibration is applied to the Cu portion. I found a problem that sometimes cracks occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to bend and caulk the Cu portion at the tip of the shaft to fix the shaft to another member. It is an object of the present invention to provide a battery terminal having suitable mechanical properties and a method for manufacturing the same, which can have suitable mechanical properties for maintaining its fixed state (crimped state).

As a result of intensive studies to solve the above problems, the inventors of the present application have found that the Cu portion at the tip of the shaft portion of the battery terminal is composed of crystal grains having an appropriate cross-sectional area. It has been found that it can have favorable mechanical properties. And the present invention was completed.

That is, the battery terminal according to the first aspect of the present invention is a state in which 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 laminated in this order. a shank extending from the Al layer side to the Cu layer side, a flange extending radially from the side of the shank, and a recess surrounded by a wall further extending from the tip of the shank on the Cu layer side, and the cross-sectional area of the Cu crystal grains forming the Cu portion of the Cu layer of the wall is 10 μm ² or more and 100 μm ² or less on the axial cut surface of the shaft.

A battery terminal according to a first aspect of the present invention comprises a shaft portion extending from an Al layer side to a Cu layer side, a collar portion extending radially from a side of the shaft portion, and a distal end of the shaft portion extending toward the Cu layer side. The cross-sectional area of the Cu crystal grains forming the Cu portion of the Cu layer of the wall is 10 μm ² or more and 100 μm ² or less in the axial cut surface of the shaft. With this configuration, the cross-sectional area of the Cu crystal grains forming the Cu portion of the Cu layer of the wall is 10 μm ² or more and 100 μm ² or less in the axial cut surface of the shaft. Since the Cu portion at the tip has an appropriate Vickers hardness, it can have sufficient workability. Therefore, by bending and crimping the Cu portion at the tip of the shaft, it is possible to have mechanical properties suitable for fixing to another member, and at the same time, it is suitable for maintaining the fixed state (crimped state). It can have mechanical properties. Specifically, since the Cu portion at the tip of the shaft portion of the battery terminal is bent and crimped to fix it to another member, the bent Cu portion is required to have mechanical properties to withstand bending and crimping. A Cu portion having a cross-sectional area of Cu crystal grains of 10 μm ² or more and 100 μm ² or less can have mechanical properties such that cracks are less likely to occur when bent and crimped, and can withstand bending and crimping. Further, in order to maintain a firm fixed state (crimped state) between the battery terminal and other members, the crimped Cu portion is required to have mechanical properties to maintain the fixed state. The Cu portion, in which the cross-sectional area of the Cu crystal grain is 10 μm ² or more and 100 μm ² or less, is bent and crimped to fix it to another member, and then cracks are less likely to occur when an external force such as vibration is applied. It can have mechanical properties to withstand conditions over time.

In the battery terminal according to the first aspect of the present invention, the cross-sectional area of the Cu crystal grains forming the Cu portion is preferably 65 μm ² or less. With this configuration, the cross-sectional area of the Cu crystal grains constituting the Cu portion is (10 μm ² or more) 65 μm ² or less, so that the workability of the Cu portion at the tip of the shaft portion can be improved. By bending and crimping the Cu portion at the tip of the shaft, it is possible to have more suitable mechanical properties for fixing to another member, and to maintain the fixed state (crimped state). can have properties. As a result, it is possible to sufficiently suppress the occurrence of cracks when the Cu portion is bent and crimped, and sufficiently prevent the occurrence of cracks when an external force such as vibration is applied to the crimped Cu portion. can be suppressed.

More preferably, in the battery terminal according to the first aspect of the present invention, the cross-sectional area of the Cu crystal grains forming the Cu portion is 40 μm ² or less. With this configuration, the cross-sectional area of the Cu crystal grains forming the Cu portion is 10 μm ² or more and 40 μm ² or less, so that the workability of the Cu portion at the tip of the shaft portion can be further improved. Regardless of the shape of the terminal, by bending and crimping the Cu portion at the tip of the shaft, it is possible to have sufficient and appropriate mechanical properties to fix it to another member, and the fixed state (crimping) state) can have more suitable mechanical properties. As a result, it is possible to sufficiently suppress the occurrence of cracks when the Cu portion is bent and crimped, and sufficiently prevent the occurrence of cracks when an external force such as vibration is applied to the crimped Cu portion. can be suppressed.

In the battery terminal according to the first aspect, the Cu portion preferably has a Vickers hardness of 110 HV or more and 125 HV or less. Here, when the Vickers hardness of the Cu portion at the tip of the shaft exceeds 125 HV, the workability becomes too poor, and when the Vickers hardness of the Cu portion at the tip of the shaft is less than 110 HV, the workability becomes too good. Therefore, with this configuration, the Cu portion at the tip of the shaft has an appropriate Vickers hardness, so that the Cu portion at the tip of the shaft can have mechanical properties suitable for bending and crimping. At the same time, it can have appropriate mechanical properties such that cracks are less likely to occur when an external force such as vibration is applied to the crimped Cu portion.

A method for manufacturing a battery terminal according to a second aspect of the present invention comprises 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 this order, in a state of being laminated. By forming a clad material composed of an Al material and a Cu material, and pressing the clad material, an Al layer composed of the Al material of the clad material and a Cu layer composed of the Cu material of the clad material are formed. , which are laminated in this order and joined to form a shaft portion extending from the Al layer side to the Cu layer side, a collar portion extending radially from the side of the shaft portion, and a wall portion extending toward the Cu layer side at the tip of the shaft portion. and a step of forming a battery terminal including a concave portion surrounded by the A step of pressing the clad material so that the cross-sectional area of the Cu crystal grains is 10 μm ² or more and 100 μm ^{2 or} less is included.

In the method for manufacturing a battery terminal according to the second aspect of the present invention, the cross-sectional area of the Cu crystal grains forming the Cu portion of the Cu layer of the wall is 10 μm ² or more and 100 μm ² in the axial cut surface of the shaft. It includes a step of pressing the clad material as follows. With this configuration, the Cu portion made of the Cu layer of the wall portion can be press-worked so as to have sufficient hardness, so that the Cu portion has sufficient workability and can be bent and crimped to form another member. A Cu portion having mechanical properties suitable for fixing to the tip of the shaft can be formed at the tip of the shaft, and a Cu portion having mechanical properties suitable for maintaining the fixed state (crimped state) is formed. can do. Specifically, in order to fix the Cu portion at the tip of the shaft portion of the battery terminal to another member by bending and crimping, the Cu portion to be bent (especially the Cu portion in the base region of the wall portion) must be: Mechanical properties to withstand bending and crimping are required. The Cu portion press-formed so that the cross-sectional area of the Cu crystal grains is 10 μm ² or more and 100 μm ² or less has mechanical properties such that cracks are less likely to occur when bent and crimped, and can withstand bending and crimping. can. Further, in order to maintain a sound fixed state (crimped state) between the battery terminal and other members, the crimped Cu portion is required to have mechanical properties to maintain the fixed state. The Cu part (especially the Cu part in the base region of the wall) press-formed so that the cross-sectional area of the Cu crystal grains is 10 μm ² or more and 100 μm ² or less is bent and crimped to fix it to another member, and then vibrate. It can have mechanical properties such that cracks are less likely to occur when an external force such as the like is applied, and the fixed state can be endured over time.

In the method for manufacturing a battery terminal according to the second aspect of the present invention, preferably, the step of forming the battery terminal includes forming the clad material so that the cross-sectional area of the Cu crystal grains constituting the Cu portion is 65 μm ² or less. Including the process of pressing. With this configuration, the clad material is pressed so that the cross-sectional area of the Cu crystal grains constituting the Cu portion is (10 μm ² or more) 65 μm ² or less, thereby improving the workability of the Cu portion at the tip of the shaft portion. Since the clad material can be pressed so as to improve the strength, the Cu portion at the tip of the shaft is bent and crimped to form a Cu portion having more suitable mechanical properties for fixing to another member. be able to. As a result, the Cu portion can further suppress the occurrence of cracks when bent and crimped, and sufficiently prevent the occurrence of cracks when an external force such as vibration is applied to the crimped Cu portion. can be suppressed.

In the method for manufacturing a battery terminal according to the second aspect of the present invention, more preferably, the step of forming the battery terminal includes: forming the clad material so that the cross-sectional area of Cu crystal grains constituting the Cu portion is 40 μm ² or less; including the step of pressing. With this configuration, the clad material is press-worked so that the cross-sectional area of the Cu crystal grains constituting the Cu portion is 10 μm ² or more and 40 μm ² or less, thereby improving the workability of the Cu portion at the tip of the shaft portion. Since the clad material can be press-formed to improve the performance, it is sufficiently suitable for fixing to other members by bending and crimping the Cu portion at the tip of the shaft regardless of the shape of the battery terminal. A Cu portion having good mechanical properties can be formed. As a result, the Cu portion can sufficiently suppress the occurrence of cracks when bent and crimped, and sufficiently prevent the occurrence of cracks when an external force such as vibration is applied to the crimped Cu portion. can be suppressed to

In the method for manufacturing a battery terminal according to the second aspect, preferably, in the step of forming the battery terminal, the cross-sectional area of the Cu crystal grains constituting the Cu material is set to S1 in a cut surface in the thickness direction of the clad material. , When the cross-sectional area of the Cu crystal grains constituting the Cu portion is S2 in the axial cut surface of the shaft portion, the deformation rate of the Cu crystal grains before and after press working obtained by (S1−S2)/S1×100 is A step of forming recesses so as to be 45% or more and less than 100% is included. With this configuration, by forming the recesses so that the deformation rate is 45% or more and less than 100%, the Cu portion having a smaller cross-sectional area of the Cu crystal grains than the Cu material of the clad material before press working is formed. can do. As a result, since the cross-sectional area of the Cu crystal grains constituting the Cu portion is formed to be small, the mechanical properties such as elongation are improved, and the occurrence of cracks when the Cu portion is bent and crimped can be suppressed. In addition, it is possible to suppress the occurrence of cracks when an external force such as vibration is applied to the crimped Cu portion.

In the method for manufacturing a battery terminal according to the second aspect, preferably, the step of forming the battery terminal includes the step of forming recesses so that the deformation ratio is 60% or more. With this configuration, in the concave portion formed so that the deformation rate is 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, since the cross-sectional area of the Cu crystal grains constituting the Cu portion is formed smaller, the mechanical properties such as elongation are further improved, and the occurrence of cracks when the Cu portion is bent and crimped can be sufficiently prevented. In addition, it is possible to sufficiently suppress the occurrence of cracks when an external force such as vibration is applied to the crimped Cu portion.

In the method for manufacturing a battery terminal according to the second aspect, preferably, in the step of forming the clad material, the clad material has a Vickers hardness of 70 HV or less at a cut surface in the thickness direction of the clad material. The step of forming the material is included. With this configuration, since the Cu material of the clad material has a Vickers hardness of 70 HV or less, the workability during press working is appropriately improved, and the cross-sectional area of the Cu crystal grains constituting the Cu portion after press working is reduced. A suitable size can be formed, and the Cu portion after press working can be formed to have an appropriate Vickers hardness.

In the method for manufacturing a battery terminal according to the second aspect, preferably, the step of forming the battery terminal includes a step of pressing the clad material so that the Cu portion has a Vickers hardness of 110 HV or more and 125 HV or less. include. With this configuration, by setting the Vickers hardness of the Cu portion after press working to 110 HV or more and 125 HV or less, it has mechanical properties suitable for bending and crimping, and external force such as vibration after crimping is eliminated. A Cu part can be obtained that has suitable mechanical properties that are less susceptible to cracking when subjected to stress.

According to the present invention, as described above, the Cu portion at the tip of the shaft portion is bent and crimped to have mechanical properties suitable for fixing to another member, and the fixed state (crimped state) is obtained. It is possible to provide a battery terminal and a manufacturing method thereof that can have suitable mechanical properties to maintain.

1 is a perspective view showing an assembled battery according to an embodiment of the present invention; FIG. 1 is a perspective view showing the overall configuration of a lithium ion battery according to an embodiment of the invention; FIG. 1 is an exploded perspective view showing the overall configuration of a lithium ion battery according to an embodiment of the present invention; FIG. 1 is a cross-sectional view showing a positive electrode terminal of a lithium ion battery according to an embodiment of the present invention; FIG. FIG. 4 is a cross-sectional view showing how the positive electrode terminal of the lithium ion battery according to the embodiment of the present invention is crimped to the lid member. FIG. 4 is a cross-sectional view showing a negative terminal according to an embodiment of the present invention; FIG. 4 is a cross-sectional view showing another example of a negative terminal according to an embodiment of the present invention; FIG. 4 is a diagram (photograph) showing a part of an electron microscope image of the Cu portion of the negative electrode terminal according to the embodiment of the present invention. FIG. 4 is a cross-sectional view showing how the negative terminal is crimped to the lid member according to the embodiment of the present invention; Fig. 3 shows a clad material according to an embodiment of the invention; FIG. 4 is a diagram (photograph) showing a part of an electron microscope image of the Cu material of the clad material according to the embodiment of the present invention. It is a schematic diagram shown in order to demonstrate the manufacturing method of the clad material by embodiment of this invention. It is a figure which shows the state before press-working by embodiment of this invention. It is a figure which shows the state after press-working by embodiment of this invention. FIG. 4 is a cross-sectional view showing a state before crimping the negative electrode terminal to the lid member according to the embodiment of the present invention; FIG. 5 is a cross-sectional view showing a state in the middle of crimping the negative electrode terminal to the lid member according to the embodiment of the present invention; FIG. 4 is a cross-sectional view showing a state after the negative terminal is crimped to the lid member according to the embodiment of the present invention; FIG. 4 is a cross-sectional view showing a state of the negative electrode terminal during laser welding according to the embodiment of the present invention; It is a figure which shows the modification of a negative electrode terminal.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

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

The assembled battery 100 is a large-sized battery system used in electric vehicles (EV), hybrid electric vehicles (HEV), residential power storage systems, and the like. As shown in FIG. 1, this assembled battery 100 is configured by electrically connecting a plurality of lithium ion batteries 1 with a plurality of flat plate-like bus bars 101 (illustrated by dotted lines).

In the assembled battery 100, a plurality of lithium ion batteries 1 are arranged so as to line up along the lateral direction (X direction) of the lithium ion batteries 1 when viewed in a plan view. In the assembled battery 100, the positive electrode terminal 10 is positioned on one side (Y1 side) in the longitudinal direction (Y direction) perpendicular to the lateral direction when viewed in a plan view, and is positioned on the other side (Y2 side) in the Y direction. Lithium ion battery 1 (1a) in which negative terminal 20 is located and lithium ion battery 1 (1b) in which positive terminal 10 is located on the Y2 side and negative terminal 20 is located on the Y1 side are arranged along the X direction. are arranged alternately.

In addition, the negative 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 arranged in the X direction of the bus bar 101 made of pure Al and extending in the X direction. It is joined by resistance welding at one end of the direction. Thus, 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 busbar 101 . In this manner, a battery pack 100 is configured in which a plurality of lithium ion batteries 1 are connected in series.

By using the bus bar 101 made of pure Al, the weight of the bus bar 101 can be reduced as compared with the case where the bus bar made of pure Cu is used. Therefore, by using the busbars 101 made of pure Al, it is possible to reduce the weight of the entire assembled battery 100 using a plurality of busbars 101 . Here, pure Al means, for example, aluminum in the A1000 series defined by JIS standards. In addition, pure Cu means, for example, C1000 series copper specified in JIS standards such as oxygen-free copper, tough pitch copper, or phosphorous deoxidized copper.

<Structure of Lithium Battery>
As shown in FIG. 2, the lithium ion battery 1 has a substantially rectangular parallelepiped appearance. Lithium ion battery 1 includes lid member 2 arranged on one side (Z1 side) in the vertical direction (Z direction) perpendicular to the X direction and Y direction, and battery case arranged on the other side (Z2 side). A main body 3 is provided. Both the lid member 2 and the battery case main body 3 are made of a Ni-plated steel plate.

As shown in FIG. 3, the lid member 2 is formed in a flat plate shape. Also, the lid 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 in the Y direction of the lid member 2 at a predetermined interval and substantially in the center of the lid member 2 in the X direction. A positive electrode terminal 10 and a 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 laminated in a roll shape, and an electrolytic solution (not shown). The positive electrode 4a is made of Al foil coated with a positive electrode active material. The negative electrode 4b is composed 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 4b.

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

The positive electrode current collector 5 is arranged on the Y1 side so as to correspond to the positive electrode terminal 10 . 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 toward the Z2 side, and a connection connecting the leg portion 5b and the plurality of positive electrodes 4a. plate 5c. The positive electrode current collector 5 is made of pure Al, like the positive electrode 4a.

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

Insulating sealing members 7 and 8 are fitted in the insertion holes 2a and 2b of the lid member 2, respectively. The sealing member 7 is formed with a hole 7a into which the positive electrode terminal 10 is inserted. The seal member 7 prevents contact between the upper surface of the lid member 2 on the Z1 side and the inner surface of the insertion hole 2 a and the positive electrode terminal 10 , and prevents the lower surface of the lid member 2 on the Z2 side from contacting the positive electrode current collector 5 . It is arranged so as to suppress contact with the Further, the seal member 8 is formed with a hole 8a into which the negative terminal 20 is inserted. The seal member 8 prevents contact between the upper surface of the lid member 2 on the Z1 side and the inner surface of the insertion hole 2 b and the negative electrode terminal 20 . are arranged so as to suppress contact between the

(Structure of positive electrode terminal)
As shown in FIG. 3, the positive electrode terminal 10 has a columnar shaft portion 11 extending in the Z direction, and an end portion of the shaft portion 11 on the Z1 side. ) and an annular flange 12 formed to have a radial spread. The shaft portion 11 is configured to be positioned substantially at the center of the positive electrode terminal 10 in the X direction and the Y direction.

As shown in FIGS. 4 and 5, the positive electrode terminal 10 is made of pure Al, like the positive electrode current collector 5 and the bus bar 101 . Further, the positive electrode terminal 10 has a concave portion 13 formed at the end of the shaft portion 11 on the Z2 side. The positive electrode terminal 10 has a wall forming a concave portion 13 in a state in which the shaft portion 11 is inserted into the insertion hole 2a of the lid member 2 (the hole portion 7a of the seal member 7) and the hole portion 5d of the positive electrode current collector 5. It is crimped to the positive electrode current collector 5 (see FIG. 3) using a portion, and is joined and fixed to the positive electrode current collector 5 by laser welding in the crimped state. The positive electrode terminal 10 having the shaft portion 11, the flange portion 12 and the concave portion 13 is formed by pressing an Al plate material (not shown).

(Structure of negative electrode terminal)
As shown in FIGS. 6 and 7, the negative electrode terminal 20 includes a columnar shaft portion 21 extending in the Z direction, and an end portion of the shaft portion 21 on the Z1 side from the shaft portion 21 in the X direction and the Y direction (X− Y-plane direction), and has an annular flange 22 when viewed from the Z-direction. The shaft portion 21 is configured to be positioned substantially at the center of the negative electrode terminal 20 in the X direction and the Y direction. The negative electrode terminal 20 is an example of a "battery terminal" in the claims. The XY plane direction is an example of the "radial direction" in the claims.

As shown in FIG. 6, the negative electrode terminal 20 has a T shape in which the shaft portion 21 protrudes from the Al layer 31 side to the Cu layer 32 side, or has a cross shape as shown in FIG. When the negative electrode terminal 20 has a cross shape, the negative electrode terminal 20 has a first shaft portion 21 a that protrudes from the Al layer 31 side toward the Cu layer 32 side and a length that protrudes toward the Cu layer 32 side. and a second shaft portion 21b that protrudes toward the Al layer 31 with a protruding length t2 that is smaller than the length t1. A bus bar 101 may be connected to the second shaft portion 21b of the negative terminal 20 having a cross shape.

As shown in FIG. 6, the shaft portion 21 composed of the Cu layer 32 includes a solid region 25 adjacent to the Al layer 31 and a hollow region 26 including a recess 23 and a wall portion 24 surrounding the recess 23. It has 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). Of the wall portion 24 , a region from the base portion (root) in contact with the solid region 25 to the center of the wall portion 24 in the Z2 direction is particularly referred to as a base region 27 .

The concave portion 23 is formed in an annular shape like a round pipe cross section when viewed from the Z2 side. As a result, the Z2 side of the shaft portion 21 in which the concave portion 23 is formed is formed in a cylindrical shape. That is, the concave portion 23 is formed in a region surrounded by the cylindrical wall portion 24 on the outside.

In the negative electrode terminal 20 shown in FIG. 6, the Vickers hardness of the Cu portion 33 in the wall portion 24 (especially the Cu portion 33a in the base region 27) is preferably 110 HV or more and 125 HV or less. Further, the Vickers hardness of the Cu portion 33 (particularly the Cu portion 33a) is more preferably 114 HV or more and 125 HV or less, from the viewpoint of making cracks less likely to occur when an external force such as vibration is applied to the crimped Cu portion 33. More preferably 118 HV or more and 125 HV or less. The Vickers hardness is determined by the size of the area of the depression (indentation) formed when a rigid body (indenter) made of diamond is pressed into the test object.

The negative electrode terminal 20 in which the Cu portion 33 has a Vickers hardness of 110 HV or more and 125 HV or less can have mechanical properties suitable for bending and crimping the Cu portion 33, and the crimped Cu portion 33 can be vibrated. It has appropriate mechanical properties that make it difficult for cracks to occur when an external force is applied. Specifically, when the Cu portion 33 having a Vickers hardness exceeding 125 HV is bent and crimped, cracks are likely to occur in the Cu portion. Further, when a Cu portion having a Vickers hardness of less than 110 HV is bent and crimped, cracks are likely to occur when an external force such as vibration is applied to the Cu portion. Therefore, when the Cu portion 33 of the negative electrode terminal 20 has an appropriate Vickers hardness of 110 HV or more and 125 HV or less, the negative electrode terminal 20 is exposed to an external force such as vibration during use of the assembled battery 100 (lithium ion battery 1). The Cu portion 33 of 20 is less likely to crack.

The Vickers hardness is measured at Cu portion 33 of wall portion 24 (preferably Cu portion 33a of base region 27). The base region 27 of the wall portion 24 is the portion most susceptible to cracking when the Cu portion 33 of the wall portion 24 is bent and crimped. If a crack occurs in the base region 27 of the wall portion 24, good connection between the negative electrode terminal 20 and another member (negative electrode current collector 6) cannot be achieved. 33a is a particularly important part. Therefore, it is preferable to measure the Vickers hardness of the Cu portion 33 a of the base region 27 of the wall portion 24 . 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. The thickness in the Y plane direction) is the same. 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 FIGS. 6 and 8, the cross-sectional area of the Cu crystal grains (for example, the Cu crystal grains 34) of the Cu portion 33 (especially the Cu portion 33a of the base region 27) of the Cu layer 32 of the wall portion 24 is 10 μm ^{2 .} It is more than 100 μm ² or less. When the cross-sectional area of the Cu crystal grains of the Cu portion 33a of the wall portion 24 is 10 μm ² or more and 100 μm ² or less, the wall portion 24 is bent and crimped to fix it to another member (negative electrode current collector 6). It can have suitable mechanical properties as well as suitable mechanical properties to maintain its fixed state (crimped state). That is, if the cross-sectional area of the Cu crystal grains of the Cu portion 33 of the wall portion 24 (especially the Cu portion 33a of the base region 27) is 10 μm ² or more and 100 μm ^{2 or} less, cracking occurs when the wall portion 24 is bent and crimped. In addition, by bending and crimping the wall portion 24, cracks are less likely to occur when an external force such as vibration is applied after fixing to another member (negative electrode current collector 6).

In addition, from the viewpoint of obtaining suitable mechanical properties for bending and crimping the wall portion 24 and also obtaining suitable mechanical properties for maintaining the fixed state (crimped state), the Cu portion 33 of the wall portion 24 The cross-sectional area of the Cu crystal grains (for example, the Cu crystal grains 34) of (in particular, the Cu portion 33a of the base region 27) is preferably 10 μm ² or more and 65 μm ² or less, more preferably 10 μm ² or more and 40 μm ^{2 or} less. Note that the Vickers hardness of the Cu portion 33a tends to increase as the area of the Cu crystal grains forming the Cu portion 33a decreases. When the cross-sectional area of the Cu crystal grains of the Cu portion 33 of the wall portion 24 (especially the Cu portion 33a of the base region 27) is excessively reduced to less than 10 μm ² , the Vickers hardness of the Cu portion 33 becomes excessively large. , exceeds the upper limit of the Vickers hardness (125 HV) described above. Therefore, the workability of the Cu portion 33 becomes too poor, and cracks are likely to occur when the wall portion 24 is bent and crimped. Further, when the cross-sectional area of the Cu crystal grains of the Cu portion 33 of the wall portion 24 (especially the Cu portion 33a of the base region 27) becomes excessively large and exceeds 100 μm ² , the Vickers hardness of the Cu portion 33 becomes excessively small. As a result, it is less than the lower limit (110 HV) of the Vickers hardness described above. Therefore, the durability of the Cu portion 33 becomes too poor, and cracks are likely to occur when an external force such as vibration is applied to the Cu portion 33 after the wall portion 24 has been bent and crimped. Here, the cross-sectional area of the Cu crystal grains of the Cu portion 33 (for example, the Cu crystal grains 34) is measured using an electron microscope in a cross section obtained by cutting the wall portion 24 in the direction in which the shaft portion 21 extends (Z direction). The cross-sectional area of the Cu grains of Cu portion 33 (eg Cu grains 34 ) is preferably measured at base region 27 of wall portion 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 general electron microscope and a general image analysis system attached thereto. Specifically, for example, under an electron microscope, contour (grain boundary) enhancement processing (for example, processing for drawing contour lines of Cu crystal grains 34) of Cu crystal grains (for example, Cu crystal grains 34) constituting the Cu portion 33 is performed. and the area within the contour (grain boundary) is defined as the cross-sectional area of the Cu crystal grain (for example, the Cu crystal grain 34). The processing for obtaining the cross-sectional area of the Cu crystal grains is performed on any and a 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). The average value obtained by dividing the total value of the cross-sectional areas of the Cu crystal grains by the number of Cu crystal grains is obtained, and the cross-sectional area (average cross-sectional area) of the Cu crystal grains of the Cu portion 33 in the electron microscope image is obtained.

As shown in FIGS. 6 and 8, the Cu crystal grains (for example, Cu crystal grains 34) of the Cu portion 33 of the Cu layer 32 in the base region 27 of the wall portion 24 are formed into a substantially acicular shape having an extremely large aspect ratio by press working. was found to take the form of Therefore, in the present embodiment, as an index indicating the Cu crystal grains of the Cu portion 33 (Cu portion 33a), instead of the general grain size (equivalent circle diameter), the above-described cross-sectional area (average cross-sectional area) is adopted. . Specifically, in the Cu portion 33 of the wall portion 24 (preferably the Cu portion 33a of the base region 27), for example, an electron microscope image of a region containing the Cu crystal grains 34 is obtained, and the Cu crystal grains in this region are obtained. A cross-sectional area (average cross-sectional area) S2 is obtained, and using the cross-sectional area (average cross-sectional area) S1 of the Cu crystal grains forming the Cu material 320 (see FIG. 10) of the clad material before press working, the Cu portion 33 (Cu The deformation rate D of the Cu crystal grains before and after press working of the portion 33a) is obtained by the following formula 1.

From Equation 1, the deformation rate D is 0% when the cross-sectional areas of the Cu crystal grains before and after the press working of the Cu portion 33 are the same. In addition, regarding the deformation rate D, the cross-sectional area S2 of the Cu crystal grains of the Cu portion 33 after press working is smaller than the cross-sectional area S1 of the Cu crystal grains of the Cu material 320 (see FIG. 10) before press working (S2<S1 ), then 0%<D<100%. Therefore, it means that the Cu crystal grains of the Cu portion 33 after press working are more deformed than the Cu crystal grains of the Cu material 320 before press working as the deformation rate D increases. Therefore, when the deformation ratio D satisfies 0%<D<100%, the hardness of the Cu portion 33 after press working is lower than the hardness of the Cu material 320 before press working due to work hardening caused by press working. can also be made larger. By reducing the cross-sectional area of the Cu crystal grains of the Cu portion 33a of the base region 27 of the wall portion 24, the cross-sectional area of the Cu crystal grains of the Cu portion 33b of the wall portion 24 other than the base region 27 is similarly reduced. Conceivable. Also, when the Vickers hardness of the Cu portion 33 (especially the Cu portion 33a of the base region 27) is moderately higher than the Vickers hardness of the Cu material 320 before press working (for example, 70 HV or less), for example, 110 HV or more and 125 HV or less. , cracks are less likely to occur when the wall portion 24 is bent and crimped. From this point of view, the deformation rate D of the Cu crystal grains before and after press working of the Cu portion 33 (especially the Cu portion 33a of the base region 27) is preferably 45% or more, more preferably 60% or more.

As shown in FIG. 9, the negative electrode terminal 20 is inserted into the insertion hole 2b of the lid member 2 (the hole 8a of the seal member 8) and the hole 6d of the negative electrode current collector 6 with the shaft portion 21 inserted into the concave portion. A wall portion 24 forming 23 is bent and crimped to the negative electrode current collector 6, and further joined and fixed to the negative electrode current collector 6 by laser welding. The shape of the concave portion 23 when viewed from the Z2 direction is not particularly limited, but may be, for example, a circular shape, an elliptical shape, or a rectangular shape with rounded four corners.

As shown in FIG. 10, the negative terminal 20 (see FIG. 3) is produced by pressing a clad material 300. As shown in FIG. The clad material 300 is a state in which 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 are laminated in the Z direction. It is formed using a clad material 300 having a two-layer structure composed of an Al material 310 and a Cu material 320 by being rolled and joined. Then, the Al plate material 131 and the Cu plate material 132 that have been rolled (clad rolled) and joined together are atomically (chemically) joined by further performing an appropriate heat treatment. As a result, the cladding material 300 having a two-layer structure of the Al material 310 composed of the Al plate material 131 and the Cu material 320 composed of the Cu plate material 132 is subjected to pressing accompanied by large deformation for manufacturing the negative electrode terminal 20 . It can have sufficient bonding strength to withstand processing.

The Al material 310 of the clad material 300 corresponds to the Al layer 31 of the negative terminal 20 . As pure Al constituting the Al material 310 of the clad material 300, that is, the Al layer 31 of the negative electrode terminal 20, about 99% by mass or more of Al such as A1050 (JIS standard), A1100 (JIS standard), A1200 (JIS standard), etc. It is possible to use pure Al containing Al. As the Al-based alloy, A5000 series (JIS standard) such as A5052 may be used, and A3000 series (JIS standard) may also 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 terminal 20 . As the Cu material 320 of the clad material 300, that is, the pure Cu forming the Cu layer 32 and the Cu portion 33 of the negative electrode terminal 20, C1000 series (JIS standard), so-called oxygen-free copper, phosphorus-deoxidized copper, tough pitch copper, or the like is used. It is also possible to use C1510 (JIS standard) to which a trace amount of Zr is added in order to suppress coarsening of crystals. As the Cu-based alloy, it is possible to use C2000 series (JIS standard) such as C2600.

The Cu crystal grains of the Cu material 320 forming the clad material 130 (see, for example, the Cu crystal grains 340 shown in FIG. 11) are work-hardened by the press work performed to manufacture the negative electrode terminal 20 . Therefore, the Vickers hardness of the Cu material 320 forming the clad material 130 is preferably 70 HV or less. When the Cu material 320 of the clad material 300 has a Vickers hardness of 70 HV or less on a cut surface in the thickness direction of the clad material 300, workability during press working is appropriately improved. The cross-sectional area of the Cu crystal grains (for example, the Cu crystal grains 34) constituting the Cu portion 33 can be formed to have an appropriate size, and the Cu portion 33 can be formed with an appropriate hardness, for example, a Vickers hardness of 110 HV or more and 125 HV or less. can be formed into

As shown in FIG. 11, in a cross section along the thickness direction (Z direction) of the clad material 300, the cross-sectional area of the Cu crystal grains (for example, the Cu crystal grains 340) forming the Cu material 320 is preferably 40 μm ² or more. It is 750 μm ² or less, more preferably 40 μm ² or more and 500 μm ² or less. The cross-sectional area of the Cu crystal grains constituting the Cu material 320 is preferably 40 μm ² or more and 750 μm ² or less, more preferably 40 μm ² or more and 500 μm ² or less. By pressing so as to be less than, 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 FIGS. ² or less (preferably 10 μm ² or more and 65 μm ² or less, more preferably 10 μm ² or more and 40 μm ^{2 or} less). If the cross-sectional area of the Cu crystal grains of the Cu material 320 before press working is less than 40 μm ² , the Cu material 320 becomes difficult to press. Further, when the cross-sectional area of the Cu crystal grains of the Cu material 320 before press working exceeds 750 μm ² , the Cu material 320 has a cross-sectional area of the Cu crystal grains of the Cu portion 33 of the wall portion 24 after press working of 100 μm ² or less. In addition, it becomes difficult to increase the hardness of the Cu portion 33 . Here, the cross-sectional area of the Cu crystal grains (for example, the Cu crystal grains 340) forming the Cu material 320 is the cross-sectional area of the Cu crystal grains (for example, the Cu crystal grains 34) of the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20. Similarly, it can be determined by the method of determining the average cross-sectional area of the Cu crystal grains described above.

(Manufacturing method of negative electrode terminal)
Next, a method for manufacturing the negative terminal 20 according to the present embodiment will be described with reference to FIGS. 12 to 14. FIG.

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 between the thickness of the Al plate material 131 and the thickness of the Cu plate material 132 is substantially the same as the ratio of the thicknesses in the Z direction between the Al layer 31 and the Cu layer 32 that constitute the flange portion 22 of the negative electrode terminal 20 (see FIG. 6). Become. Here, the thickness of the Al plate material 131 may be the same as the thickness of the Cu plate material 132 . Further, the thickness of the Cu plate member 132 may be made larger than that of the Al plate member 131 depending on the size of the shaft portion 21 of the negative electrode terminal 20 after press working (amount of protrusion to the Z2 side, shaft diameter). In order to make the workability of the Cu plate material 132 during clad rolling closer to the workability of the Al plate material 131, the Cu plate material 132 before clad rolling may be subjected to temper treatment such as temper rolling and softening annealing.

A strip-shaped Al plate material 131 and a strip-shaped Cu plate material 132 are laminated in the thickness direction, and are continuously rolled at a predetermined rolling reduction using rollers R. As a result, a band-shaped clad material 130 having a two-layer structure is produced in which the Al plate material 131 and the Cu plate material 132 are laminated in the thickness direction and joined together. At this time, the longitudinal direction of the strip-shaped Al plate material 131 and the strip-shaped Cu plate material 132 is the rolling direction. As a result, a band-shaped clad material 130 is produced in which the Al plate material 131 and the Cu plate material 132 are laminated in the thickness direction and joined (rolled jointed) to each other. The number of passes for clad rolling can be selected as appropriate.

Then, after performing intermediate rolling or the like as necessary, the clad material 130 is held in an annealing furnace 50 for a predetermined time under a predetermined atmosphere and a holding temperature at which the Al plate material 131 does not melt, thereby performing diffusion annealing. I do. The holding temperature is, for example, a temperature below the melting point of the Al plate material 131 . This causes moderate metal diffusion at the interface where the Al plate material 131 and the Cu plate material 132 are joined, and increases the bonding 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 bonding strength between the Al plate material 131 and the Cu plate material 132 sufficiently higher than the bonding strength of the plating film. Furthermore, finish rolling, shape correction, and softening annealing at a holding temperature at which the Al plate material 131 is not melted may be performed as necessary. Then, using the strip-shaped clad material 130, a clad material 300 having a two-layer structure and an individual piece shape as shown in FIG. That is, the clad material 300 in the form of individual pieces is manufactured in which the Al material 310 and the Cu material 320 are laminated in the thickness direction and joined together. The piece-shaped clad material 300 is manufactured, for example, after slitting the clad material 130 .

In the step of producing the clad material 130, when forming the piece-like clad material 300 using the band-like clad material 130, a cut surface in the thickness direction (Z direction) of the piece-like clad material 300 is preferably is such that the Vickers hardness of the Cu material 320 is 70 HV or less, and preferably the cross-sectional area of the Cu crystal grains constituting the Cu material 320 is preferably 40 μm ² or more and 750 μm ² or less, more preferably 40 μm ² or more and 500 μm Rolling and diffusion annealing are preferably performed so that the hardness becomes ² or less, and finish rolling, shape correction, softening annealing, etc. are preferably performed as necessary.

Next, the clad material 300 in the form of individual pieces, in which the Al material 310 and the Cu material 320 are laminated in the thickness direction and joined together, is used to form the negative electrode terminal 20 shown in FIG. 6, for example. In the step of forming the negative electrode terminal 20, as shown in FIG. 13, the piece-shaped clad material 300 is pressed. Specifically, first, the piece-like clad material 300 is arranged in the cavity 41 b of the mold 41 a of the press machine 41 . A cavity 41b of this mold 41a has a cavity shape corresponding to, for example, the shaft portion 21, the flange portion 22 and the recess portion 23 of the negative electrode terminal 20 shown in FIG. Then, as shown in FIG. 14, the clad material 300 is pressed 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 41 b on the Z2 side corresponding to the shaft portion 21 .

In the step of pressing, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 of the wall portion 24 (especially the Cu portion 33a of the base region 27) of the negative electrode terminal 20 after pressing is preferably 10 μm ² or more and 100 μm ² or less. The clad material 300 is pressed so that the thickness is 10 μm ² or more and 65 μm ² or less, more preferably 10 μm ² or more and 40 μm ^{2 or} less.

Further, preferably, in the step of press working, in a cross section of the clad material 300 in the thickness direction, the cross-sectional area of the Cu crystal grains forming the Cu material 320 is set to S1, and the axial direction (Z direction) of the shaft portion 21 is cut. On the surface, when the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 is S2, the deformation rate D of the Cu crystal grains before and after press working, which is obtained by (S1−S2)/S1×100, is 45% or more, more preferably. The clad material 300 is press-worked so that the is 60% or more.

Further, preferably, the step of pressing is performed so that the Cu portion 33 has a Vickers hardness of 110 HV or more and 125 HV or less, or a Vickers hardness of 114 HV or more, on a cut surface in the axial direction (Z direction) of the shaft portion 21 . The clad material 300 is pressed so as to have a more preferable Vickers hardness of 125 HV or less, or a more preferable Vickers hardness of 118 HV or more and 125 HV or less.

(Welding process of negative electrode terminal)
Next, the process of welding the negative terminal 20 to the negative current collector 6 in this embodiment will be described with reference to FIGS. 9 and 15 to 18. FIG.

First, as shown in FIG. 15, the cover member 2 having the seal member 8 fitted in the insertion hole 2b is prepared. 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 crimping jig 103 is brought into contact with the Z2 side surface of the negative electrode current collector 6 and fixed. In this state, the rod-shaped member 103b of the crimping 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-shaped member 103 b is fitted into the concave portion 23 of the negative electrode terminal 20 .

Then, the pressing member 103c of the crimping jig 103 presses the negative electrode terminal 20 from the Z1 side toward the Z2 side. As a result, as shown in FIG. 16, the negative terminal 20 is moved to the Z2 side together with the rod-shaped member 103b. Then, the negative electrode terminal 20 is moved by the pressing force of the pressing member 103c until the end of the wall portion 24 on the Z2 side is positioned on the Z2 side of the insertion hole 2b. Subsequently, the negative electrode terminal 20 is moved to the Z2 side while the Cu portion 33 of the cylindrical wall portion 24 is deformed along the outer peripheral surface of the rod-shaped member 103b. Subsequently, the negative electrode terminal 20 is moved to the Z2 side while the Cu portion 33 of the cylindrical wall portion 24 is further deformed along the Z1 side concave surface of the fixing member 103a of the crimping jig 103 . After that, when the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20 is bent and deformed into a shape as shown in FIG. 17, the movement of the rod-shaped member 103b stops. As a result, the wall portion 24 of the negative electrode terminal 20 is bent to have a semicircular cross section as shown in FIG. 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 that is radially bent in the XY plane direction.

Thereafter, as shown in FIG. 18, the crimped negative electrode terminal 20 and the negative electrode current collector 6 are welded by laser welding. Specifically, the portion on the tip side of the wall portion 24 that is radially bent in the XY plane direction of the negative electrode terminal 20 is annularly welded to the connection portion 6a of the negative electrode current collector 6 to be joined. 9, the tip of the Z2 side wall portion 24 of the negative electrode terminal 20, which is the side to be 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.

<Effects of this embodiment>
The following effects can be obtained in this embodiment.

In this 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 collar portion 22 extending radially from the side of the shaft portion 21 , and the Cu layer 32 side of the shaft portion 21 . and a concave portion 23 surrounded by a wall portion 24 further extending from the tip of the shaft portion 21, and a cross-sectional area of Cu crystal grains constituting a Cu portion 33 composed of the Cu layer 32 of the wall portion 24 in the axial cut surface of the shaft portion 21. is 10 μm ² or more and 100 μm ² or less. As a result, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 of the Cu layer 32 of the wall portion 24 is 10 μm ² or more and 100 μm ² or less on the axial cut surface of the shaft portion 21 . Since the Cu portion 33 at the tip of has an appropriate Vickers hardness, it can have sufficient workability. Therefore, by bending and crimping the Cu portion 33 (Cu portion 33b) at the tip of the shaft portion 21, it is possible to have mechanical properties suitable for fixing to another member, and its fixed state (crimped state). It can have suitable mechanical properties to maintain Specifically, the Cu portion 33 (Cu portion 33b) at the tip of the shaft portion of the negative electrode terminal 20 is bent and crimped to be bent into the Cu portion 33 (Cu portion 33b) to be bent in order to be fixed to another member. And mechanical properties to withstand caulking are required. The Cu portion 33 in which the cross-sectional area of the Cu crystal grains is 10 μm ² or more and 100 μm ^{2 or} less can have mechanical properties such that cracks are less likely to occur when bent and crimped. Further, in order to maintain a firm fixed state (crimped state) between the negative electrode terminal 20 and other members, the crimped Cu portion 33 (Cu portion 33b) is required to have mechanical properties to maintain the fixed state. be done. The Cu portion 33 (Cu portion 33b) in which the cross-sectional area of the Cu crystal grain is 10 μm ² or more and 100 μm ^{2 or} less cracks when an external force such as vibration is applied after being fixed to another member by bending and crimping. It can have mechanical properties that allow it to withstand its fixed state over time.

In this embodiment, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 is 65 μm ² or less. As a result, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 is (10 μm ² or more) 65 μm ² or less, so that the workability of the Cu portion 33 (Cu portion 33b) at the tip of the shaft portion 21 is improved. Therefore, by bending and crimping the Cu portion 33 at the tip of the shaft portion 21, it is possible to have more suitable mechanical properties for fixing to another member, and the fixed state (crimped state) is maintained. have sufficient and suitable mechanical properties for As a result, the occurrence of cracks when the Cu portion 33 (Cu portion 33b) is bent and crimped can be sufficiently suppressed, and external force such as vibration is applied to the crimped Cu portion 33 (Cu portion 33b). It is possible to sufficiently suppress the occurrence of cracks when applied.

In this embodiment, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 is 40 μm ² or less (10 μm ² or more). Accordingly, since the cross-sectional area of the Cu crystal grains forming the Cu portion 33 is 40 μm ² or less, the workability of the Cu portion 33 (Cu portion 33b) at the tip of the shaft portion 21 can be further improved. Regardless of the shape of the negative electrode terminal 20, by bending and crimping the Cu portion 33 (Cu portion 33b) at the tip of the shaft portion 21, it is possible to obtain mechanical properties more suitable for fixing to another member. , can have more favorable mechanical properties to maintain its fixed state (crimped state). As a result, it is possible to sufficiently suppress the occurrence of cracks when the Cu portion 33 is bent and crimped, and cracking occurs when an external force such as vibration is applied to the crimped Cu portion 33 (Cu portion 33b). can be sufficiently suppressed.

In this embodiment, the Cu portion 33 has a Vickers hardness of 110 HV or more and 125 HV or less. Accordingly, since the Cu portion 33 at the tip of the shaft portion 21 has an appropriate Vickers hardness, the Cu portion 33 at the tip of the shaft portion 21 can have mechanical properties suitable for bending and crimping. The crimped Cu portion 33 can have appropriate mechanical properties such that cracks are less likely to occur when an external force such as vibration is applied.

In the method for manufacturing the negative terminal 20 according to the present embodiment, the Cu crystal forming the Cu portion 33 (in particular, the Cu portion 33a of the base region 27) composed of the Cu layer 32 of the wall portion 24 is formed on the axial cut surface of the shaft portion 21. A step of pressing the clad material 300 so that the cross-sectional area of the grains is 10 μm ² or more and 100 μm ^{2 or} less is included. As a result, the Cu portion 33 made of the Cu layer 32 of the wall portion 24 can be press-worked so as to have sufficient hardness. A Cu portion 33 having mechanical properties suitable for fixing to the tip of the shaft portion 21 can be formed at the tip of the shaft portion 21, and the Cu portion having mechanical properties suitable for maintaining the fixed state (crimped state). 33 can be formed. Specifically, in order to fix the Cu portion 33 at the tip of the shaft portion 21 of the negative electrode terminal 20 to another member by bending and crimping, the bent Cu portion 33 (especially the Cu portion 33a of the base region 27) is bent. Also, mechanical properties to withstand bending and crimping are required. The Cu portion 33 press-formed so that the cross-sectional area of the Cu crystal grains is 10 μm ² or more and 100 μm ² or less has a mechanical property to withstand bending and crimping such that cracks are less likely to occur when bent and crimped. can be done. In order to maintain a sound fixed state (crimped state) between the negative electrode terminal 20 and other members, the crimped Cu portion 33 is required to have mechanical properties to maintain the fixed state. The Cu portion 33 (particularly the Cu portion 33a of the base region 27 of the wall portion 24) press-formed so that the cross-sectional area of the Cu crystal grains is 10 μm ² or more and 100 μm ² or less is bent and crimped to be attached to another member. It can have mechanical properties such that cracks are less likely to occur when an external force such as vibration is applied after being fixed, so that the fixed state can be endured over time.

In this embodiment, the step of forming the negative electrode terminal 20 includes a step of pressing the clad material 300 so that the cross-sectional area of the Cu crystal grains forming the Cu portion 33 is 40 μm ² or less. As a result, the clad material 300 is pressed so that the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 is (10 μm ² or more) 65 μm ² or less, thereby improving the workability of the Cu portion 33 at the tip of the shaft portion 21. Since the clad material 300 can be press-worked so as to improve the strength, the Cu portion 33 at the tip of the shaft portion 21 is bent and crimped to fix the Cu portion to another member. 33 can be formed. As a result, when the Cu portion 33 is bent and crimped, the occurrence of cracks can be further suppressed, and the occurrence of cracks when an external force such as vibration is applied to the crimped Cu portion 33 can be suppressed. can be sufficiently suppressed.

In this embodiment, the step of forming the negative electrode terminal 20 includes a step of pressing the clad material 300 so that the cross-sectional area of the Cu crystal grains forming the Cu portion 33 is 40 μm ² or less. As a result, the clad material 300 is pressed so that the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 is (10 μm ² or more) 40 μm ² or less, thereby improving the workability of the Cu portion 33 at the tip of the shaft portion 21. Since the clad material 300 can be press-worked so as to further improve the strength, the Cu portion 33 at the tip of the shaft portion 21 is bent and crimped to fix it to another member. A portion 33 can be formed. As a result, the Cu portion 33 can sufficiently suppress the occurrence of cracks when it is bent and crimped, and cracks can be prevented from occurring when an external force such as vibration is applied to the crimped Cu portion 33. can be sufficiently suppressed.

In the present embodiment, the step of forming the negative electrode terminal 20 is performed by setting the cross-sectional area of the Cu crystal grains forming the Cu material 320 to be S1 in the cut surface in the thickness direction of the clad material 300, and the cut surface in the axial direction of the shaft portion 21. , when the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 is S2, the deformation rate of the Cu crystal grains before and after press working obtained by (S1−S2)/S1×100 is 45% or more and less than 100%. , a step of forming recesses 23 is included. As a result, the recesses 23 are formed so that the deformation ratio is 45% or more and less than 100%, thereby forming the Cu portion 33 having a smaller cross-sectional area of the Cu crystal grains than the Cu material 320 of the clad material 300 before press working. can do. As a result, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 is formed to be small, so that the mechanical properties such as elongation are improved, and the occurrence of cracks when the Cu portion 33 is bent and crimped is suppressed. In addition, it is possible to suppress the occurrence of cracks when an external force such as vibration is applied to the crimped Cu portion 33 .

In this embodiment, the step of forming the negative electrode terminal 20 includes the step of forming the concave portion 23 so that the deformation ratio is 60% or more (less than 100%). As a result, in the concave portion 23 formed to have a deformation rate of 60% or more (less than 100%), the Cu portion 33 has a smaller cross-sectional area of the 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 forming the Cu portion 33 is formed to be smaller, the mechanical properties such as elongation are further improved, and cracks occur when the Cu portion 33 is bent and crimped. This can be sufficiently suppressed, and the occurrence of cracks when an external force such as vibration is applied to the crimped Cu portion 33 can be sufficiently suppressed.

In the present embodiment, the step of forming the clad material 300 is to form the clad material 300 so that the Cu material 320 has a Vickers hardness of 70 HV or less at a cut surface in the thickness direction (Z direction) of the clad material 300. Including process. As a result, since the Vickers hardness of the Cu material 320 of the clad material 300 is 70 HV or less, the workability during press working is appropriately improved, and the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 after press working is suitable. In addition, the Cu portion 33 after press working can be formed to have an appropriate Vickers hardness.

In the present embodiment, the step of forming the negative electrode terminal 20 includes a step of pressing the clad material 300 so that the Cu portion 33 has a Vickers hardness of 110 HV or more and 125 HV or less. As a result, it is possible to obtain the Cu portion 33 that has suitable mechanical properties for bending and crimping, and also has appropriate mechanical properties that make cracking less likely to occur when an external force such as vibration is applied after crimping. can.

[Example 1]
Clad materials 300 of Examples (No. 1 to No. 20) were produced in the same manner as in the manufacturing method of the above embodiment. At that time, as shown in FIG. 12, a clad material 130 is produced by performing clad rolling and diffusion annealing, and from the clad material 130, a clad material 300 having a two-layer structure as shown in FIG. 20 was made to have a predetermined shape.

The prepared clad material 300 is a cut surface 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 Corporation). The cross-sectional area of Cu crystal grains was measured. Table 1 shows the measurement results.

Then, when the Vickers hardness of the Cu material 320 was measured on a cut surface in the thickness direction (Z direction) of a plurality of cladding materials 300 arbitrarily selected from the manufactured cladding materials 300, the results were, for example, 58HV, 60HV, and 67HV. , the range was from 58 HV to 67 HV, and the average value was 61.7 HV. The Vickers hardness was measured according to JIS Z2244:2009 (load 0.49N).

Next, by using the produced clad material 300, press working as shown in FIGS. did. Note that the press working of the clad material 300 is performed when the cross-sectional area of the Cu crystal grains forming the Cu portion 33 of the Cu layer 32 of the wall portion 24 of the negative electrode terminal 20 is 10 μm ² or more and 100 μm ² or less, preferably 10 μm ² or more and 65 μm ^{2 or more} . Below, more preferably, it was adjusted to fall within the range of 10 μm ² or more and 40 μm ² or less.

The prepared negative electrode terminal 20 was measured by using the area measurement function attached to a digital microscope (VHX-5000 manufactured by Keyence Corporation), and the cut surface in the axial direction (Z direction) of the shaft portion 21 of the negative electrode terminal 20 was Cu. The cross-sectional area of Cu crystal grains forming part 33 (Cu part 33a) was measured. Table 1 shows the measurement results.

Then, arbitrarily selected from the negative terminals 20 of the examples (No. 1 to No. 20), No. 21 to No. 30 and its No. 21 to No. The Vickers hardness of the Cu material 320 was measured on the cut surface in the axial direction (Z direction) of the shaft portion 21 of the negative electrode terminal 20 of No. 30. The Vickers hardness was measured according to JIS Z2244:2009 (load 0.49N). Table 2 shows the measurement results.

As shown in Table 1, No. In the case of No. 1, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 194 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 20 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 90%.

No. In the case of No. 2, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 117 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 62 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 47%.

No. 3, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 495 μm ² . Moreover, the cross-sectional area of the Cu crystal grains of the Cu portion 33 in the negative electrode terminal 20 after press working was about 16 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 97%.

No. 4, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 331 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 36 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 89%.

No. 5, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 172 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 18 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 89%.

No. 6, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 186 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 25 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 86%.

No. 7, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 244 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 13 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 95%.

No. 8, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 323 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 45 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 86%.

No. 9, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 65 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 20 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 69%.

No. 10, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 59 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 23 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 61%.

No. 11, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 286 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 37 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 87%.

No. 12, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 729 μm ² . In addition, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 31 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 96%.

No. In the case of No. 13, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 218 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 25 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 88%.

No. 14, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 697 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 26 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 96%.

No. 15, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 132 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 22 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 83%.

No. 16, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 162 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 53 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 67%.

No. 17, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 414 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was the smallest, about 11 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 97%.

No. In the case of No. 18, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 173 μm ² . In addition, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 34 μm ² . The deformation ratio D of the cross-sectional area of the Cu crystal grains before and after press working was about 80%.

No. In the case of No. 19, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 183 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 25 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 86%.

No. 20, the cross-sectional area of the Cu crystal grains forming the Cu material 320 in the clad material 300 before press working was about 173 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 59 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 66%.

Also, as shown in Table 2, No. 21 and no. In the case of No. 22, the Vickers hardness of the Cu portion 33 in the negative electrode terminal 20 after press working was about 123 HV.

No. 23 and no. In the case of No. 24, the Vickers hardness of the Cu portion 33 in the negative electrode terminal 20 after press working was about 122 HV.

No. 25, No. 26, No. 27, No. 28, No. 29 and no. 30, the Vickers hardness of the Cu portion 33 in the negative electrode terminal 20 after pressing was about 118 HV, about 119 HV, about 121 HV, about 120 HV, about 125 HV and about 118 HV, respectively.

[Example 2]
Clad materials 300 of Example 2 (No. 31 to No. 60) were produced in the same manner as in Example 1 above. Then, using the produced clad material 300, negative terminals 20 of Example 2 (No. 31 to No. 60) were produced in the same manner as in Example 1 above. Note that the press working of the clad material 300 is performed in the same manner as in the first embodiment, so that the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 of the Cu layer 32 of the wall portion 24 of the negative electrode terminal 20 is 10 μm ² or more and 100 μm. ² or less, preferably 10 μm ² or more and 65 μm ² or less, more preferably 10 μm ² or more and 40 μm ² or less. As a result, as shown in Table 3, the cross-sectional area of the Cu crystal grains of the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20 fell within an appropriate range of 10 μm ² or more and 100 μm ² or less. In addition, in Example 2, a clad material 300 different from that in Example 1 was used to produce a negative electrode terminal 20 different from that in Example 1. FIG. The clad material 300 of Example 2 has an overall volume ratio of about 2.5 times that of Example 1, and the volume ratio of the Cu material 320 is about 2.5 times. In the negative electrode terminal 20 of Example 2, the volume ratio of the portion of the shaft portion 21 closer to Z2 than the collar portion 22 (the portion indicated by t1 in FIG. 7) is about 4.5 times that of Example 1. , the volume ratio of the other portions is about 3 times, the volume ratio of the wall portion 24 is about 6 times, and the thickness (wall thickness) of the wall portion 24 is about 3 times.

For the clad material 300 thus produced, the cross-sectional area of the Cu crystal grains constituting the Cu material 320 was measured on the cut surface in the thickness direction (Z direction) of the clad material 300 in the same manner as in Example 1 above. Table 3 shows the measurement results.

Then, the Vickers hardness of the Cu material 320 was measured in the same manner as in Example 1 on cut surfaces in the thickness direction (Z direction) of a plurality of cladding materials 300 arbitrarily selected from the manufactured cladding materials 300. , for example, 63HV, 64HV, 68HV, etc. The range was 63HV or more and 68HV or less, and the average value was 65.0HV.

In the negative electrode terminal 20 thus produced, as in the case of the first embodiment, the Cu crystal grains forming the Cu portion 33 (Cu portion 33a) are formed on the cut surface in the axial direction (Z direction) of the shaft portion 21 of the negative electrode terminal 20. was measured. Table 3 shows the measurement results.

And no. 31 to No. No. 61 to No. 60 are arbitrarily selected from the negative terminals 20 of No. 70 and its No. 61 to No. The Vickers hardness of the Cu material 320 was measured on the cut surface in the axial direction (Z direction) of the shaft portion 21 of the negative electrode terminal 20 of No. 70. Table 4 shows the measurement results.

As shown in Table 3, No. 31, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 322 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 52 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 84%.

No. 32, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 175 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 47 μm ² . The deformation ratio D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 73%.

No. In the case of No. 33, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 230 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 42 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 82%.

No. 34, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 249 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 57 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 77%.

No. 35, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 263 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 61 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 77%.

No. 36, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 181 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 56 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 69%.

No. 37, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 101 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 29 μm ² . The deformation ratio D of the cross-sectional area of the Cu crystal grains before and after press working was about 71%.

No. 38, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 150 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 40 μm ² . The deformation ratio D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 73%.

No. In the case of No. 39, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 194 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 46 μm ² . The deformation ratio D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 76%.

No. 40, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 402 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 92 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 77%.

No. 41, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 280 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 63 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 78%.

No. 42, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 321 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 52 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 84%.

No. 43, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 183 μm ² . In addition, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 31 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 83%.

No. 44, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 221 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 50 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 77%.

No. 45, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 287 μm ² . In addition, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was the largest, approximately 94 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 67%.

No. 46, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 151 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 38 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 75%.

No. 47, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 438 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 47 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 89%.

No. 48, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 201 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 66 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 67%.

No. 49, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 105 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 24 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 77%.

No. 50, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 444 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 72 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 84%.

No. 51, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 47 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 14 μm ² . The deformation ratio D of the cross-sectional area of the Cu crystal grains before and after press working was about 71%.

No. 52, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 456 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 68 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 85%.

No. 53, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 331 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 39 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 88%.

No. 54, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 101 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 21 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 79%.

No. 55, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 342 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 49 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 86%.

No. 56, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 280 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 28 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 90%.

No. 57, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 245 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 54 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 78%.

No. 58, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 161 μm ² . Moreover, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 22 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was about 86%.

No. 59, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 287 μm ² . Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was approximately 36 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 87%.

No. 60, the cross-sectional area of the Cu crystal grains of the Cu material 320 in the clad material 300 before press working was about 207 μm ² . In addition, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 in the negative electrode terminal 20 after press working was about 34 μm ² . The deformation rate D of the cross-sectional area of the Cu crystal grains before and after press working was approximately 83%.

Also, as shown in Table 4, No. 61 and no. In the case of No. 67, the Vickers hardness of the Cu portion 33 in the negative terminal 20 after press working was about 124 HV.

No. 62, No. 66 and no. In the case of No. 68, the Vickers hardness of the Cu portion 33 in the negative electrode terminal 20 after press working was about 121 HV.

No. 63, No. 64, No. 65, No. 69 and no. 70, the Vickers hardness of the Cu portion 33 in the negative electrode terminal 20 after pressing was about 119 HV, about 123 HV, about 122 HV, about 118 HV and about 120 HV, respectively.

When the clad materials 300 (Nos. 1 to 20 and Nos. 31 to 60) of Examples 1 and 2 were pressed to produce the negative terminal 20, the Cu layer of the wall portion 24 of the negative terminal 20 The cross-sectional areas of the Cu crystal grains forming the Cu portion 33 composed of 32 were confirmed. Further, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20 (No. 1 to 20) of Example 1 is in a more appropriate range of 10 μm ² or more and 65 μm ² or less. I was able to confirm that. In addition, the cross-sectional area of the Cu crystal grains forming the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20 (No. 31 to No. 60) of Example 2 is in an appropriate range of 10 μm ² or more and 100 μm ² or less. I was able to confirm that Furthermore, it was confirmed that cracks did not occur particularly in the wall portions 24 of the negative terminals 20 (No. 1 to No. 20 and No. 31 to No. 60) of Examples 1 and 2. . In particular, No. In the clad material No. 40, the cross-sectional area of the Cu crystal grains is 94 μm ² , and the crystal grains are the largest among the examples, and the Vickers hardness is 118 HV, which is a hardness with sufficient workability. It had mechanical strength. Also, No. The clad material No. 41 had a cross-sectional area of Cu crystal grains of 63 μm ² and a Vickers hardness of 122 HV, so that the workability was further improved and it had sufficient mechanical strength. Also, No. The 29 clad material has a cross-sectional area of 11 μm ² of Cu crystal grains, which is the smallest among the examples, but has the highest Vickers hardness of 125 HV, and has sufficient workability and optimal mechanical strength. had.

From the results of Examples 1 and 2, the inventors of the present application have determined that the cross-sectional area of the Cu crystal grains forming the Cu portion 33 of the Cu layer 32 of the wall portion 24 of the negative electrode terminal 20 is 10 μm ² or more and 100 μm ^{2 or} less. It was found that the negative electrode terminal 20 as shown in FIG. 6 can be produced from the clad material 300 as shown in FIG. 10 by pressing the clad material 300 as shown in FIG.

In addition, the inventors of the present application obtained the results obtained from the results of Examples 1 and 2, and the results of considering the error (variation) in the Vickers hardness that may occur during manufacturing. It was found that the Vickers hardness can be set to 110 HV or more and 125 HV or less by pressing the clad material 300 so that the cross-sectional area of the crystal grains is 10 μm ² or more and 100 μm ² or less. In addition, the inventors of the present application found that the Cu crystal constituting the Cu portion 33 It was found that the Vickers hardness can be set to 115 HV or more and 125 HV or less by pressing the clad material 300 so that the grain cross-sectional area is 10 μm ² or more and 65 μm ^{2 or} less. The inventor of the present application found that the Vickers hardness can be set to 118 HV or more and 125 HV or less by adjusting the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 to 10 μm ² or more and 40 μm ² or less. Ta.

In addition, the inventor of the present application is No. From the result of No. 67 and the result of No. 69, even when the difference in the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 is about 60 μm ² , the difference in Vickers hardness is within the range of 6 HV. . Also, from this result, the inventor of the present application found that the Vickers hardness did not fall below 110 HV when the cross-sectional area of the Cu crystal grains was increased from 94 μm ² of No. 69 to 100 μm ² . Then, using a clad material 300 as shown in FIG. 10, press working is performed so that the cross-sectional area of the Cu crystal grains constituting the Cu portion 33 of the Cu layer 32 of the wall portion 24 is 10 μm ² or more and 100 μm ² or less. It was found that the negative electrode terminal 20 manufactured by the above method can have a Cu portion 33 having an appropriate hardness with a Vickers hardness of 110 HV or more and 125 HV or less.

Further, the inventors of the present application have found that the negative electrode terminal 20 in which the cross-sectional area of the Cu crystal grains forming the Cu portion 33 of the Cu layer 32 of the wall portion 24 is 10 μm ² or more and 100 μm ² or less is a clad material as shown in FIG. 300, the Cu crystal grains (cross-sectional area S1) constituting the Cu material 320 of the clad material 300 are pressed so that the deformation rate D of the cross-sectional area of the Cu crystal grains is 45% or more and less than 100%. It has been found that it is possible to produce

Further, the inventors of the present application have found that the negative electrode terminal 20 in which the cross-sectional area of the Cu crystal grains forming the Cu portion 33 of the Cu layer 32 of the wall portion 24 is 10 μm ² or more and 100 μm ² or less is such that the Vickers hardness of the Cu material 320 is Using the clad material 300 shown in FIG. 10 which is 70 HV or less, the Vickers hardness of the Cu portion 33 composed of the Cu layer 32 of the wall portion 24 is 110 HV or more and 125 HV or less at a deformation rate D of 45% or more and less than 100%. It was found that it can be produced by press working so as to be.

Next, using the negative terminals 20 (No. 1 to No. 20 and No. 31 to No. 60) fabricated in Examples 1 and 2, the electrodes shown in FIGS. The wall portion 24 is bent, crimped, and laser-welded as described above to obtain a fixed state (crimped state). At that time, it was confirmed that no cracks occurred in the negative electrode terminal 20 (in particular, the base region 27 of the wall portion 24). From this result, the inventors of the ^present application used the clad material 300 as shown in ^FIG . Since the Cu portion 33 at the tip of the shaft portion 21 is composed of Cu crystal grains having an appropriate cross-sectional area, the Cu portion at the tip of the shaft portion 21 is It has been found that bending and crimping 33 can provide suitable mechanical properties for fixing to other members.

Next, after setting the negative terminals 20 (No. 1 to No. 20 and No. 31 to No. 60) of Examples 1 and 2 to the above-described fixed state (crimped state), they were appropriately continued to vibrate. At that time, it was confirmed that no cracks occurred in the negative electrode terminal 20 (in particular, the base region 27 of the wall portion 24). From this result, the inventors of the ^present application used the clad material 300 as shown in ^FIG . Since the Cu portion 33 at the tip of the shaft portion 21 is composed of Cu crystal grains having an appropriate cross-sectional area, the Cu portion at the tip of the shaft portion 21 is It has been found that it can have mechanical properties suitable for withstanding and maintaining a fixed state (crimped state) in which 33 is bent and crimped over time.

[Modification]
It should be noted that the embodiments and examples disclosed this time should be considered illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the description of the above-described embodiments and examples, and includes all changes (modifications) within the meaning and scope equivalent to the scope of 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 three-layer structure in which an Al layer, a Cu layer, and a Ni layer are laminated in this order and bonded together may be used.

Moreover, 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 joined together is shown, but the present invention is not limited to this. In the present invention, a three-layer structure or more may be used. In that case, for example, it may be a four-layer clad material, or a four-layer clad material in which an Al layer, a Ni layer, a Cu layer, and a Ni layer are laminated in this order and joined. . In the case of a three-layer structure or more, the clad material has sufficient mechanical strength if the cross-sectional area of the crystal grains of the Cu portion of the Cu layer is 10 μm ² or more and 100 μm ² or less.

Further, in the present embodiment, an example in which the Cu portion 33 of the wall portion 24 of the negative electrode terminal 20, which is a battery terminal, is bent is shown, but the present invention is not limited to this. In the present invention, for example, as shown in FIG. 19, a battery terminal in which the Cu portion of the wall portion is flared may be used.

Moreover, in the present embodiment, an example in which the 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, the Vickers hardness or the like may be measured at the tip of the Cu portion 33 of the wall portion 24 on the Z2 side.

Further, in the present embodiment, an example in which the concave portion 23 is formed in an annular shape like a round pipe cross section when viewed from the Z2 side is shown, but the present invention is not limited to this. In the present invention, the concave portion does not have to be annular when viewed from the Z2 direction, and may have, for example, a rectangular shape.

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

Moreover, in the present embodiment, an example in which the battery terminal is used as the negative electrode terminal 20 of the assembled battery 100 is shown, but the present invention is not limited to this. In the present invention, the battery terminal may be used as the negative electrode terminal of the cell.

20 Negative terminal (terminal for battery)
21 Shaft 22 Collar 23 Recess 24 Wall 27 Base region 31 Al layer 32 Cu layer 33 Cu portion 130 Clad material (band-shaped clad material)
131 Al plate material 132 Cu plate material 300 Clad material (piece-shaped clad material)
310 Al material 320 Cu material

Claims (11)

an Al layer (31) made of pure Al or an Al-based alloy;
A Cu layer (32) composed of pure Cu or a Cu-based alloy is composed of a clad material joined in a state of being laminated in this order,
A shaft portion (21) extending from the Al layer side to the Cu layer side, a collar portion (22) extending radially from the side of the shaft portion, and a wall further extending from the tip of the shaft portion on the Cu layer side. a recess (23) surrounded by a portion;
In the battery terminal, the cross-sectional area of Cu crystal grains forming the Cu portion of the Cu layer of the wall portion is 10 μm ² or more and 100 μm ² or less in the axial cut surface of the shaft portion. The battery terminal according to claim 1, wherein a cross-sectional area of Cu crystal grains forming said Cu portion is 65 µm ² or less. 3. The battery terminal according to claim ² , wherein a cross-sectional area of Cu crystal grains forming said Cu portion is 40 [mu]m<2> or less. 4. The battery terminal according to claim 1, wherein said Cu portion has a Vickers hardness of 110 HV or more and 125 HV or less. An Al plate material (131) made of pure Al or an Al-based alloy and a Cu plate material (132) made of pure Cu or a Cu-based alloy are laminated in this order and joined to form an Al material (310) and a Cu material. forming a clad material (300) composed of (320);
By pressing the clad material, the Al layer (31) made of the Al material of the clad material and the Cu layer (32) made of the Cu material of the clad material are laminated in this order and joined. A shaft portion (21) extending from the Al layer side to the Cu layer side, a collar portion (22) extending radially from the side of the shaft portion, and a wall portion further extending from the tip of the shaft portion on the Cu layer side. forming a battery terminal comprising a recess (23) surrounded by
In the step of forming the battery terminal, the cross-sectional area of Cu crystal grains forming the Cu portion of the Cu layer of the wall portion is 10 μm ² or more and 100 μm ² or less on the axial cut surface of the shaft portion. A method for manufacturing a battery terminal, comprising the step of pressing the clad material. The battery according to claim 5, wherein the step of forming the battery terminal includes a step of pressing the clad material so that the cross-sectional area of the Cu crystal grains constituting the Cu portion is 65 μm ² or less. Terminal manufacturing method. The battery according to claim 6, wherein the step of forming the battery terminal includes a step of pressing the clad material so that the cross-sectional area of the Cu crystal grains constituting the Cu portion is 40 μm ² or less. Terminal manufacturing method. In the step of forming the battery terminal, in a cut surface in the thickness direction of the clad material, the cross-sectional area of the Cu crystal grains constituting the Cu material is set to S1, and in a cut surface in the axial direction of the shaft portion, the Cu When the cross-sectional area of the Cu crystal grains constituting the part is S2, the above-mentioned The method for manufacturing a battery terminal according to any one of claims 5 to 7, comprising the step of forming recesses. 9. The method for manufacturing a battery terminal according to claim 8, wherein the step of forming the battery terminal includes the step of forming the concave portion so that the deformation ratio is 60% or more. Claims 5 to 9, wherein the step of forming the clad material includes a step of forming the clad material so that the Vickers hardness of the Cu material is 70 HV or less at a cut surface in the thickness direction of the clad material. A method for manufacturing a battery terminal according to any one of the above. The step of forming the battery terminal according to any one of claims 5 to 10, wherein the step of forming the battery terminal includes a step of pressing the clad material so that the Cu portion has a Vickers hardness of 110 HV or more and 125 HV or less. and a method for manufacturing a battery terminal.

Images