Battery terminal, method for manufacturing battery terminal, battery, and method for manufacturing battery

Abstract

This negative electrode terminal (battery terminal) (10) is provided with: a flange section (12) in which an Al layer (41) comprising an Al alloy and a Cu layer (42) comprising Cu are diffusion-bonded in the lamination direction, the Al alloy containing Al in the maximum content and Mn or Mg in the second maximum content, and having a conductivity of 30% IACS or more; a shaft part (11) extending from the flange part in the stacking direction of the Al layer and the Cu layer; and a recess (13) that is located at the Cu layer-side end of the shaft part and has a surface comprising a Cu layer.

Description

Technical Field

[0001] The present invention relates to a battery terminal, a method for manufacturing a battery terminal, a battery, and a method for manufacturing a battery, and particularly relates to a battery terminal having a recess, a method for manufacturing a battery terminal, a battery, and a method for manufacturing a battery. Background Art

[0002] Conventionally, a battery terminal having a recess has been known. Such a battery terminal has been disclosed, for example, in Japanese Patent No. 6581440.

[0003] Japanese Patent No. 6581440 discloses a battery terminal made of a composite material, having a shaft portion, a flange portion, and a recess provided at the front end of the shaft portion. The composite material is formed by joining a first metal layer (Al layer) made of pure Al and a second metal layer (Cu layer) made of pure Cu. In Patent Document 1, by stamping the composite material from the Al layer side to the Cu layer side in the stacking direction, a shaft portion and a recess having a surface made of the Cu layer are formed.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent No. 6581440 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] Here, although not disclosed in the above-mentioned Japanese Patent No. 6581440 Gazette, there is a case where, from the viewpoint of stamping processability, annealing is performed on the composite material in order to soften pure Cu, which is harder than pure Al, before stamping. At this time, since the softening temperatures of pure Al and pure Cu are close, pure Al is also softened simultaneously by the annealing of pure Cu. When stamping a composite material in which an Al layer made of pure Al and a Cu layer made of pure Cu are softened by annealing to form a shaft portion and a recess having a surface made of a Cu layer, since the Al layer is softened together with the Cu layer, the stamping processability is good. However, depending on the size and shape of the terminal, there is a case where the Al layer, which is softer than the Cu layer, extends more greatly than the Cu layer. The Al layer that extends excessively compared to the Cu layer pierces the Cu layer and exposes to the surface at a portion that requires a surface made of a Cu layer, particularly at the side wall portion of the recess that becomes a thin wall. For example, in a state where the Al layer is exposed to the surface of the side wall portion of the recess, when the side wall portion (riveting portion) of the recess is expanded and riveted in a battery, there is a possibility that the electrolyte contacts the Al layer exposed to the surface of the side wall portion of the recess. When the Al layer dissolves at the recess riveted in the battery, the dissolved portion becomes a gap, making it difficult for current to flow, and the electrical characteristics of the battery may deteriorate.

[0009] The present invention has been made to solve the above-described technical problems, and an object of the present invention is to provide a battery terminal that can suppress the exposure of the Al layer at a portion that requires a surface made of a Cu layer (particularly the side wall portion of the recess that becomes a thin wall) while maintaining the electrical characteristics of the battery.

[0010] Means for Solving the Technical Problems

[0011] To achieve the above object, a battery terminal according to a first aspect of the present invention includes: a flange portion formed by diffusion bonding an Al layer made of an Al alloy and a Cu layer made of Cu in a stacking direction, wherein the Al alloy contains Al having the largest content and Mn or Mg having the second largest content and has a conductivity of 30% IACS or more; a shaft portion extending from the flange portion in the stacking direction of the Al layer and the Cu layer; and a recess located at an end portion on the Cu layer side of the shaft portion and having a surface made of a Cu layer.

[0012] In the battery terminal according to the first aspect of the present invention, as described above, the Al layer made of an Al alloy and the Cu layer made of Cu are diffusion-bonded in the stacking direction. The Al alloy contains Al with the highest content and Mn or Mg with the second highest content and has a conductivity of 30% IACS or more. The Al layer made of an Al alloy containing Mn or Mg has a higher hardness than the Al layer made of pure Al. Therefore, compared with the Al layer made of pure Al, a decrease in the hardness of the Al layer when annealing softens the Cu layer made of Cu can be suppressed. In the case of the process of performing stamping after annealing, the Al layer made of an Al alloy containing Mn or Mg has a higher hardness of the Al layer after annealing than the Al layer made of pure Al. Therefore, excessive extension of the Al layer can be suppressed. As a result, it can be suppressed that the Al layer pierces the Cu layer on the surface of the side wall portion constituting the recess and is exposed on the surface of the side wall portion of the recess. According to this structure, exposure of the Al layer on the surface of the recess can be suppressed. Therefore, it can be suppressed that the Al layer comes into contact with the electrolyte and dissolves at the recess riveted in the battery, thereby forming a gap in the recess, and a decrease in the electrical characteristics of the battery can be suppressed. In addition, since the conductivity is 30% IACS or more, the conductivity required to function as a battery terminal can be ensured. In this regard, the electrical characteristics of the battery can also be maintained. As a result, a battery terminal can be provided that can suppress exposure of the Al layer at a portion where the surface needs to be made of the Cu layer (especially the side wall portion of the recess that becomes a thin wall) while maintaining the electrical characteristics of the battery.

[0013] In the battery terminal according to the first aspect described above, it is preferable that the Al alloy has a conductivity of 40% IACS or more. By adopting such a technical solution, the conductivity required to function as a battery terminal can be sufficiently ensured.

[0014] In the battery terminal according to the first aspect described above, the Al alloy contains Al with the highest content and Mn with the second highest content. Here, the Al layer formed of the Al alloy containing Al with the highest content and Mn with the second highest content has a reduced hardness compared to the Al layer formed of the Al alloy containing Al with the highest content and Mg with the second highest content. Therefore, the Al layer formed of the Al alloy containing Al with the highest content and Mn with the second highest content can suppress the reduction in the hardness of the Al layer caused by annealing compared to the Al layer formed of pure Al. On the other hand, compared to the Al layer formed of the Al alloy containing Al with the highest content and Mg with the second highest content, it can increase the reduction in the hardness of the Al layer caused by annealing. Therefore, the Al layer formed of the Al alloy containing Al with the highest content and Mn with the second highest content can suppress the Al layer from extending too much compared to the Cu layer and can improve the stamping processability compared to the Al layer formed of the Al alloy containing Al with the highest content and Mg with the second highest content. Regarding the above aspect, the inventors of the present application have learned through the following examples (simulations). In addition, the Al layer formed of the Al alloy with the second highest Mn content has a higher conductivity than the Al layer formed of the Al alloy with the second highest Mg content, and thus can sufficiently ensure the conductivity required to function as a battery terminal. In this regard, the electrical characteristics of the battery can also be maintained.

[0015] In the manufacturing method of the battery terminal according to the second aspect of the present invention, it includes: a step of preparing a composite material by diffusion bonding an Al layer made of an Al alloy and a Cu layer made of Cu in the stacking direction, wherein the Al alloy contains Al with the highest content and Mn or Mg with the second highest content and has a conductivity of 30% IACS or more; a step of tempering the composite material into a blank for stamping, the blank for stamping being a material for stamping formed by diffusion bonding an Al layer with a Vickers hardness of 30 HV or more and a Cu layer with a Vickers hardness of 50 HV or more and 80 HV or less in the stacking direction; a step of performing stamping on the blank for stamping so as to form a flange portion, a shaft portion, and a recess portion, wherein the shaft portion extends in the stacking direction of the Al layer and the Cu layer from the flange portion, and the recess portion is located at the end portion on the Cu layer side of the shaft portion and has a surface formed of the Cu layer.

[0016] In the manufacturing method of the battery terminal according to the second aspect of the present invention, as described above, it includes a step of preparing a composite material obtained by diffusion bonding an Al layer made of an Al alloy and a Cu layer made of Cu in the stacking direction. Among them, the Al alloy contains the most Al and the second most Mn or Mg and has a conductivity of 30% IACS or more. Thus, the Vickers hardness of the Al layer is 30 HV or more, so it is possible to suppress the Al layer from piercing the Cu layer on the surface of the side wall portion constituting the recess and exposing it on the surface of the side wall portion of the recess. Regarding this effect, the inventors of the present application have learned through the following examples (simulations). Thus, it is possible to suppress the Al layer from being exposed on the surface of the side wall portion of the recess, so it is possible to suppress the electrolyte from contacting the exposed Al layer and forming a gap in the Al layer, thereby suppressing the deterioration of the electrical characteristics of the battery. In addition, since the conductivity is 30% IACS or more, it is possible to ensure the conductivity required to function as a battery terminal. In this regard, the electrical characteristics of the battery can also be maintained. As a result, it is possible to manufacture a battery terminal that can suppress the exposure of the Al layer in a portion where the surface needs to be made of the Cu layer (especially the side wall portion of the recess that becomes a thin wall) while maintaining the electrical characteristics of the battery.

[0017] In the manufacturing method of the battery terminal according to the second aspect above, it is preferable that in the step of tempering into a blank for stamping, the Vickers hardness of the Al layer is tempered to 30 HV or more and 75 HV or less, and the Vickers hardness of the Cu layer is tempered to 50 HV or more and 80 HV or less. By adopting such a technical solution, it is possible to suppress the Al layer from piercing the Cu layer on the surface of the side wall portion constituting the recess and exposing it on the surface of the side wall portion of the recess during stamping. Regarding this effect, the inventors of the present application have learned through the following examples (simulations).

[0018] In the manufacturing method of the battery terminal according to the second aspect above, it is preferable that in the step of preparing the composite material, the Al layer made of an Al alloy having a conductivity of 40% IACS or more and the Cu layer made of Cu are diffusion bonded in the stacking direction to prepare the composite material. By adopting such a technical solution, since the Al layer is made of an Al alloy having a conductivity of 40% IACS or more, the electrical characteristics of the battery can be improved compared with the case where the Al layer is made of an Al alloy having a conductivity of 30% IACS or more and less than 40% IACS.

[0019] In the battery according to the third aspect of the present invention, it includes a battery terminal, an electrolyte, a housing for storing the electrolyte, a positive electrode side member for constituting the positive electrode side of the battery, a negative electrode side member for constituting the negative electrode side of the battery, and a separator for separating the positive electrode and the negative electrode of the battery. Among them, the battery terminal includes: a flange portion formed by diffusion bonding an Al layer made of an Al alloy and a Cu layer made of Cu in the stacking direction, the Al alloy contains the most Al and the second most Mn or Mg and has a conductivity of 30% IACS or more; a shaft portion extending from the flange portion in the stacking direction of the Al layer and the Cu layer; and a concave portion located at the end of the shaft portion on the Cu layer side and having a surface formed by the Cu layer, and the concave portion of the battery terminal is fixed to the negative electrode side member by riveting.

[0020] In the battery according to the third aspect of the present invention, as described above, it includes a battery terminal, an electrolyte, a housing for storing the electrolyte, a positive electrode side member for constituting the positive electrode side of the battery, a negative electrode side member for constituting the negative electrode side of the battery, and a separator for separating the positive electrode and the negative electrode of the battery. Moreover, in the battery terminal, the Al layer made of an Al alloy and the Cu layer made of Cu are diffusion bonded in the stacking direction, wherein the Al alloy contains the most Al and the second most Mn or Mg and has a conductivity of 30% IACS or more, and the concave portion of the battery terminal is fixed to the negative electrode side member by riveting. As described above, the battery terminal can suppress the surface exposure of the Al layer at the side wall portion of the concave portion while maintaining the electrical characteristics of the battery. Therefore, it can suppress the dissolution of the Al layer in contact with the electrolyte at the concave portion of the battery terminal riveted to the negative electrode side member of the battery. Thereby, it can suppress the reduction of the electrical characteristics of the battery due to the formation of a gap at the concave portion of the battery terminal. In addition, since the conductivity is 30% IACS or more, the conductivity required to function as a battery terminal can be ensured. In this regard, the electrical characteristics of the battery can also be maintained. Since a battery terminal that can suppress the exposure of the Al layer in a portion where the surface needs to be formed by the Cu layer (especially the side wall portion of the concave portion that becomes a thin wall) is used, as a result, a battery that can suppress the reduction of the electrical characteristics caused by the battery terminal while maintaining the electrical characteristics of the battery can be provided.

[0021] In the method for manufacturing a battery according to the fourth aspect of the present invention, the battery includes a battery terminal, an electrolytic solution, a case for storing the electrolytic solution, a positive electrode side member for constituting the positive electrode side of the battery, a negative electrode side member for constituting the negative electrode side of the battery, and a separator for separating the positive electrode and the negative electrode of the battery. The battery terminal includes: a flange portion formed by diffusion bonding an Al layer made of an Al alloy and a Cu layer made of Cu in the stacking direction, the Al alloy containing the most abundant Al and the second most abundant Mn or Mg and having a conductivity of 30% IACS or more; a shaft portion extending from the flange portion in the stacking direction of the Al layer and the Cu layer; and a recess located at the end of the shaft portion on the Cu layer side and having a surface formed of the Cu layer. The method for manufacturing the battery includes a step of fixing the recess of the battery terminal to the negative electrode side member by riveting.

[0022] In the method for manufacturing a battery according to the fourth aspect of the present invention, as described above, a battery terminal is used. The battery terminal includes: a flange portion formed by diffusion bonding an Al layer made of an Al alloy and a Cu layer made of Cu in the stacking direction, the Al alloy containing the most abundant Al and the second most abundant Mn or Mg and having a conductivity of 30% IACS or more; a shaft portion extending from the flange portion in the stacking direction of the Al layer and the Cu layer; and a recess located at the end of the shaft portion on the Cu layer side and having a surface formed of the Cu layer. Moreover, the method for manufacturing the battery includes a step of fixing the recess of the battery terminal to the negative electrode side member by riveting. As described above, the battery terminal can suppress the exposure of the Al layer on the surface of the side wall portion of the recess while maintaining the electrical characteristics of the battery. Therefore, by fixing the recess of the battery terminal to the negative electrode side member of the battery by riveting, it is possible to suppress the dissolution of the Al layer in contact with the electrolytic solution at the recess of the battery terminal. Thereby, it is possible to suppress the deterioration of the electrical characteristics of the battery due to the formation of a gap at the recess of the battery terminal. In addition, since the conductivity is 30% IACS or more, it is possible to ensure the conductivity required to function as a battery terminal. In this regard, the electrical characteristics of the battery can also be maintained. Since a battery terminal that can suppress the exposure of the Al layer in a portion where the surface needs to be formed of the Cu layer (especially the side wall portion of the recess that becomes a thin wall) is used, as a result, it is possible to manufacture a battery that can suppress the deterioration of the electrical characteristics caused by the battery terminal while maintaining the electrical characteristics of the battery.

[0023] Advantages of the Invention

[0024] By adopting the present invention, it is possible to provide a battery terminal that can suppress the exposure of the Al layer in a portion where the surface needs to be formed of the Cu layer (especially the side wall portion of the recess that becomes a thin wall) while maintaining the electrical characteristics of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a diagram showing a battery pack according to an embodiment of the present invention.

[0026] Figure 2 This is a diagram showing an example of a single cell according to an embodiment of the present invention.

[0027] Figure 3 yes Figure 2 Exploded perspective view of a single battery.

[0028] Figure 4 This is a diagram showing a composite material constituting a battery terminal (negative electrode terminal) according to an embodiment of the present invention.

[0029] Figure 5 This is a diagram showing a battery terminal (negative electrode terminal) according to an embodiment of the present invention.

[0030] Figure 6 This is a diagram showing a state where a battery terminal (negative electrode terminal) according to an embodiment of the present invention is fixed by caulking.

[0031] Figure 7 It is a diagram for explaining a method for manufacturing a battery terminal (negative electrode terminal) according to an embodiment of the present invention.

[0032] Figure 8 It is a diagram for explaining the process of punching a blank for punching according to the embodiment of the present invention.

[0033] Figure 9 This is a diagram showing a cross section of the composite material and the first molded body during the first press working performed by CAE simulation, cut in the Z direction so as to pass through the central axis.

[0034] Figure 10 It is a diagram showing a cross section of the first molded body and the second molded body during the second press working performed by CAE simulation, cut in the Z direction so as to pass through the central axis.

[0035] Figure 11 It is a diagram showing a cross section of the second molded body and the third molded body during the third press working performed by CAE simulation, cut in the Z direction so as to pass through the central axis.

[0036] Figure 12 yes Figure 11 An enlarged partial view of the third molded body is shown.

[0037] Figure 13 This is a diagram (photograph) showing a cross section in the Z direction passing through the central axis of a battery terminal (negative electrode terminal) formed by actually punching a composite material corresponding to a comparative example of a CAE simulation.

[0038] Figure 14 It is a diagram showing the positions (10 positions of P1 to P10) of the third molded body of Example 1 in which the Vickers hardness is obtained by CAE simulation.

[0039] Figure 15 It is a diagram showing the positions (10 positions of P1 to P10) of the third molded body of Example 2 in which the Vickers hardness is obtained by CAE simulation.

[0040] Figure 16 It is a diagram showing the positions (10 positions of P1 to P10) of the third molded body of the comparative example in which the Vickers hardness is obtained by CAE simulation.

[0041] Figure 17 It is a diagram showing the pre - formed composite material and the post - formed battery terminal in another CAE simulation.

[0042] Figure 18 It is a diagram showing the results of the CAE simulation.

[0043] Figure 19 It is a diagram (photo) showing the battery terminal of Example 1 and the battery terminal of Comparative Example 1.

[0044] Figure 20 It is a diagram (photo) showing the cross - section of the battery terminal of Example 1.

[0045] Figure 21 It is a diagram (photo) showing the first sample of the battery terminal of Example 1 actually manufactured.

[0046] Figure 22 It is a diagram (photo) showing the second sample of the battery terminal of Example 1 actually manufactured.

[0047] Figure 23 It is a diagram (photo) showing the third sample of the battery terminal of Example 1 actually manufactured.

[0048] Figure 24 It is a diagram (photo) showing the fourth sample of the battery terminal of Example 1 actually manufactured.

[0049] Figure 25 It is a diagram (photo) showing the fifth sample of the battery terminal of Example 1 actually manufactured.

[0050] Figure 26 It is a diagram (photo) showing the sixth sample of the battery terminal of Example 1 actually manufactured.

[0051] Figure 27 It is a diagram (photo) showing the seventh sample of the battery terminal of Example 1 actually manufactured.

[0052] Figure 28 This is a diagram (photo) showing the eighth sample of the battery terminal for actually manufacturing Example 1.

[0053] Figure 29 This is a diagram (photo) showing the ninth sample of the battery terminal for actually manufacturing Example 1.

[0054] Figure 30 This is a diagram (photo) showing the tenth sample of the battery terminal for actually manufacturing Example 1.

[0055] Figure 31 This is a diagram (photo) showing the cross-section of the battery terminal of Comparative Example 1.

[0056] Figure 32 This is a diagram (photo) showing the first sample of the battery terminal for actually manufacturing Comparative Example 1.

[0057] Figure 33 This is a diagram (photo) showing the second sample of the battery terminal for actually manufacturing Comparative Example 1.

[0058] Figure 34 This is a diagram (photo) showing the third sample of the battery terminal for actually manufacturing Comparative Example 1.

[0059] Figure 35 This is a diagram (photo) showing the fourth sample of the battery terminal for actually manufacturing Comparative Example 1.

[0060] Figure 36 This is a diagram (photo) showing the fifth sample of the battery terminal for actually manufacturing Comparative Example 1.

[0061] Figure 37 This is a diagram (photo) showing the sixth sample of the battery terminal for actually manufacturing Comparative Example 1.

[0062] Figure 38 This is a diagram (photo) showing the seventh sample of the battery terminal for actually manufacturing Comparative Example 1.

[0063] Figure 39 This is a diagram showing the relationship between the Cu thickness and the Al elongation of the first to tenth samples of Example 1.

[0064] Figure 40 This is a diagram showing the relationship between the Cu thickness and the Al elongation of the first to seventh samples of the comparative example. Detailed implementation mode

[0065] Next, the implementation mode of the present invention will be described based on the accompanying drawings.

[0066] As Figure 1As shown, the battery pack 100 of the embodiment of the present invention is composed of a plurality of lithium-ion batteries 1 electrically connected by a plurality of flat busbars 101 (illustrated by dashed lines). The battery pack 100 is, for example, a large battery system mounted in an electric vehicle (EV: electric vehicle), a hybrid electric vehicle (HEV: hybrid electric vehicle), etc. Among them, the lithium-ion battery 1 is an example of the "battery" described in the claimed technical solution.

[0067] In the battery pack 100, a plurality of lithium-ion batteries 1 are arranged in a manner that, when viewed from above one side (upper side, Z1 side) in the vertical direction (Z direction), they are arranged along the short side direction (X direction) of the lithium-ion battery 1. In addition, in the battery pack 100, the lithium-ion battery 1(1a) and the lithium-ion battery 1(1b) are alternately arranged along the short side direction (X direction). In addition, in the lithium-ion battery 1a, the positive terminal 20 is located on one side (Y1 side) in the long side direction (Y direction) orthogonal to the X direction, and the negative terminal 10 is located on the other side (Y2 side) in the Y direction. In addition, in the lithium-ion battery 1b, the positive terminal 20 is located on the Y2 side, and the negative terminal 10 is located on the Y1 side. The negative terminal 10 is one of the negative side components constituting the negative side of the battery, and the positive terminal 20 is one of the positive side components constituting the positive side of the battery.

[0068] As Figure 2 and Figure 3 shown, the lithium-ion battery 1 has an appearance of a substantially rectangular parallelepiped shape. In addition, the lithium-ion battery 1 includes: a lid member 2 disposed on the Z1 side in the Z direction orthogonal to the X direction and the Y direction; and a can member 3 disposed on the other side (lower side, Z2 side). The lid member 2 and the can member 3 constitute the housing of the lithium-ion battery 1. In addition, depending on the design of the insulation structure between the positive side and the negative side, the lid member 2 and the can member 3 constituting the housing of the battery may be one of the negative side components constituting the negative side of the battery, or may be one of the positive side components constituting the positive side of the battery. Among them, the lid member 2 and the can member 3 are an example of the "housing" described in the claimed technical solution.

[0069] As Figure 3 shown, the can member 3 is formed in a substantially rectangular parallelepiped shape. An electrolyte 30 is stored in the can member 3. In addition, as Figure 3As shown, the lid member 2 is formed in a flat plate shape. In the lid member 2, a pair of insertion holes 2a and 2b are provided so as to penetrate in the Z direction. The pair of insertion holes 2a and 2b are formed at a prescribed interval in the Y direction of the lid member 2, and are formed substantially at the center in the X direction of the lid member 2. Further, a negative electrode terminal 10 and a positive electrode terminal 20 are respectively inserted and fixed in the pair of insertion holes 2a and 2b. Among them, the negative electrode terminal 10 is an example of the "battery terminal" described in the claimed technical solution.

[0070] The lithium ion battery 1 includes a power generation element 4 obtained by laminating a positive electrode 4a, a negative electrode 4b, and a separator 4c in a roll shape. The positive electrode 4a is composed of an 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 separating and insulating the positive electrode 4a and the negative electrode 4b of the battery.

[0071] The lithium ion battery 1 includes: a negative electrode current collector 5 for electrically connecting the negative electrode terminal 10 and the negative electrode 4b of the power generation element 4; and a positive electrode current collector 6 for electrically connecting the positive electrode terminal 20 and the positive electrode 4a of the power generation element 4. The negative electrode current collector 5 is disposed on the Y2 side in correspondence with the negative electrode terminal 10. Further, the negative electrode current collector 5 includes: a connecting portion 5a formed with a hole portion 5d into which the negative electrode terminal 10 is inserted; a leg portion 5b extending toward the Z2 side; and a connecting plate 5c for connecting the leg portion 5b to a plurality of negative electrodes 4b. Further, the negative electrode current collector 5 is made of Cu similarly to the negative electrode 4b. Among them, the negative electrode 4b, the negative electrode current collector 5, the connecting portion 5a, the leg portion 5b, and the connecting plate 5c are one of the negative electrode side components constituting the negative electrode side of the battery, and are an example of the "negative electrode side component" described in the claimed technical solution.

[0072] The positive electrode current collector 6 is disposed on the Y1 side in correspondence with the positive electrode terminal 20. Further, the positive electrode current collector 6 includes: a connecting portion 6a formed with a hole portion 6d into which the positive electrode terminal 20 is inserted; a leg portion 6b extending toward the Z2 side; and a connecting plate 6c for connecting the leg portion 6b to a plurality of positive electrodes 4a. Further, the positive electrode current collector 6 is made of Al similarly to the positive electrode 4a. Among them, the positive electrode 4a, the positive electrode current collector 6, the connecting portion 6a, the leg portion 6b, and the connecting plate 6c are one of the positive electrode side components constituting the positive electrode side of the battery, and are an example of the "positive electrode side component" described in the claimed technical solution.

[0073] As Figure 4 shown, the negative electrode terminal 10 is composed of a composite material 40 obtained by rolling and joining an Al layer 41 and a Cu layer 42 in a laminated state. As Figure 5As shown, the negative electrode terminal 10 includes: a flange portion 12; a shaft portion 11 that extends from the flange portion 12 toward the Z2 side in the stacking direction (Z direction) of the Al layer 41 and the Cu layer 42; and a recess portion 13 that is located at the end portion on the Cu layer 42 side (Z2 side) of the shaft portion 11 and has a surface formed of the Cu layer 42.

[0074] The Al layer 41 is made of an Al alloy. The Al alloy has a composition equivalent to that of an Al-Mn alloy of the A3000 series containing the most abundant Al and the second most abundant Mn among the alloys described in JIS-H4000:2014, or has a composition equivalent to that of an Al-Mg alloy of the A5000 series containing the most abundant Al and the second most abundant Mg.

[0075] The Al alloy of the A3000 series includes A3003 or A3004. The Al alloy of the A5000 series includes A5005, A5052, A5086, A5154, or A5454. Compared with the Al alloy of the A5000 series, the Al alloy of the A3000 series has a tendency to have a smaller Vickers hardness. Compared with the Al alloy of the A5000 series, the Al alloy of the A3000 series has a tendency to have a higher conductivity.

[0076] The conductivity of the Al layer 41 is 30% IACS or more, preferably 40% IACS. IACS is expressed as a ratio when the volume resistivity of annealed standard soft copper of 1.7241×10 -2 μΩm is 100 IACS%.

[0077] The Cu that constitutes the Cu layer 42 has a composition equivalent to that of pure copper of the C1000 series containing 99.9 mass% or more of Cu. The conductivity of the Cu layer 42 is approximately 100% IACS.

[0078] The negative electrode terminal 10 is formed by stamping, as Figure 3 and Figure 5 shown, into a shape like a rivet with the Z1 side formed of the Al layer 41 and the Z2 side formed of the Cu layer 42. The negative electrode terminal 10 is, as Figure 5 shown, a cylindrical shaft portion 11 that extends in the Z direction (stacking direction), and a circular ring-shaped flange portion 12 is formed at the end portion on the Z1 side of the shaft portion 11 and its periphery so as to radially expand in the X-Y plane direction from the shaft portion 11. In addition, a recess portion 13 is formed at the end portion on the Z2 side of the shaft portion 11 of the negative electrode terminal 10. The outer surface of the recess portion 13 is formed of the Cu layer 42. When viewed from the Z2 side, the outer peripheral portion (the portion surrounding the recess portion 13) of the recess portion 13 is formed of a circular side wall portion 13a. Among them, the Al layer 41 is Figure 5 simplified to be recorded as a rectangle in Figure 8becomes T-shaped as shown in (d).

[0079] As Figure 3 shown, an insulating seal 7 is disposed between the flange portion 12 of the negative electrode terminal 10 and the lid member 2. Further, the seal 7 has an insertion hole 7a into which the shaft portion 11 of the negative electrode terminal 10 is inserted. The flange portion 12 of the negative electrode terminal 10 is disposed on the upper side (Z1 side) of the lid member 2, and thus is disposed to be exposed outside the lithium ion battery 1. On the other hand, the portion of the shaft portion 11 of the negative electrode terminal 10 that protrudes downward (Z2 side) compared to the flange portion 12 of the shaft portion 11 is disposed inside the insertion hole 7a, the insertion hole 2a, and the lithium ion battery 1 (can member 3). The front end (recess 13) on the Z2 side of the shaft portion 11 of the negative electrode terminal 10 disposed inside the lithium ion battery 1 (can member 3) is disposed so as not to be in direct contact with the electrolyte 30.

[0080] As Figure 6 shown, when the negative electrode terminal 10 is fixed to the connecting portion 5a (negative electrode side member) of the negative electrode current collector 5 by riveting, the recess 13 on the Z2 side of the shaft portion 11 of the negative electrode terminal 10 is expanded in the X-Y plane direction. Among them, the Al layer 41 is Figure 6 simplified and described as a rectangle in, but since it extends toward the Z2 side during stamping, as a result, as Figure 8 shown in (d), it becomes T-shaped.

[0081] As Figure 3 shown, the positive electrode terminal 20 has the same outer shape as the negative electrode terminal 10. That is, the positive electrode terminal 20 has: a cylindrical shaft portion 21 extending in the Z direction; a ring-shaped flange portion 22 formed at the end portion on the Z1 side of the shaft portion 21 and its periphery so as to radially expand from the shaft portion 21 in the X-Y plane direction; and a recess 23 provided at the end portion on the Z2 side of the shaft portion 21. The positive electrode terminal 20 is made of pure Al.

[0082] Further, an insulating seal 8 is disposed between the flange portion 22 of the positive electrode terminal 20 and the lid member 2. Further, the seal 8 has an insertion hole 8a into which the shaft portion 21 of the positive electrode terminal 20 is inserted. The flange portion 22 of the positive electrode terminal 20 is disposed on the upper side (Z1 side) of the lid member 2, and thus is disposed to be exposed outside the lithium ion battery 1. On the other hand, the portion of the shaft portion 21 of the positive electrode terminal 20 that protrudes downward (Z2 side) compared to the flange portion 22 of the shaft portion 21 is disposed inside the insertion hole 8a, the insertion hole 2b, and the lithium ion battery 1 (can member 3). The front end (recess 23) on the Z2 side of the shaft portion 21 of the positive electrode terminal 20 disposed inside the lithium ion battery 1 (can member 3) is disposed so as not to be in direct contact with the electrolyte 30.

[0083] (Manufacturing Method of Terminal for Negative Electrode)

[0084] As Figure 7 shown, the manufacturing method of the terminal 10 for negative electrode includes: a step of preparing a composite material 40 obtained by rolling and joining an Al layer 41 and a Cu layer 42 in a stacked state (refer to Figure 4 ); a step of tempering the composite material 40 into a blank 51 for stamping which is a material for stamping; and a step of performing stamping on the blank 51 for stamping so as to form a flange portion 12, a shaft portion 11, and a recessed portion 13, wherein the recessed portion 13 is located at the end portion on the Z2 side of the shaft portion 11.

[0085] The step of preparing the composite material 40 is performed by rolling (composite rolling) an Al plate 410 made of an Al alloy and a Cu plate 420 made of Cu in a stacked state using a roll R and further performing diffusion annealing. The Al alloy contains Al with the largest content and Mn or Mg with the second largest content and has a conductivity of 30% IACS or more. By composite rolling, the Al plate 410 and the Cu plate 420 are plastically deformed and joined in the stacking direction. By further performing diffusion annealing, the Al plate 410 (Al layer 41) and the Cu plate 420 (Cu layer 42) are diffusion-joined in the stacking direction. Thus, a composite material 40 obtained by diffusion-joining the Al layer 41 and the Cu layer 42 in the stacking direction as Figure 4 shown is formed. At this time, it is also possible to temper the Al plate 410 and / or the Cu plate 420 in advance so that the difference in Vickers hardness between the Al plate 410 and the Cu plate 420 is reduced, and then perform composite rolling. In addition, the composite rolling can be cold rolling performed at room temperature or hot rolling performed by heating. In addition, the furnace environment and holding conditions during diffusion annealing can be selected as long as the materials of the Al plate 410 and the Cu plate 420 are considered.

[0086] The process of tempering the blank 51 for stamping is carried out by tempering the composite material 40 into a stamping blank 51 that is easily stampable, which is obtained by diffusion bonding an Al layer 41 with a Vickers hardness of 30 HV or more and a Cu layer 42 with a Vickers hardness of 50 HV or more and 80 HV or less in the stacking direction (Z direction). At this time, tempering is performed to make the Vickers hardness of the Al layer 41 of the stamping blank 51 30 HV or more. Preferably, tempering is performed to make the Vickers hardness 30 HV or more and 75 HV or less, and more preferably, tempering is performed to make the Vickers hardness 30 HV or more and 50 HV or less. In addition, in this tempering, the Vickers hardness of the Cu layer 42 of the stamping blank 51 is made 50 HV or more and 80 HV or less at the same time. For example, if the Al layer 41 is made of A1050, tempering can be performed to make its Vickers hardness about 25 HV. If the Al layer 41 is made of A3003, tempering can be performed to make its Vickers hardness about 40 HV. Or if the Al layer 41 is made of A5052, tempering can be performed to make its Vickers hardness about 60 HV. In addition, for example, if the Cu layer 42 is made of C1020, tempering can be performed to make its Vickers hardness about 55 HV.

[0087] In addition, the process of tempering the blank 51 for stamping is, for example, carried out by softening annealing (continuous annealing) in which the composite material 40 is continuously conveyed into the furnace and heated at the same time. At this time, the softening annealing is carried out, for example, in a furnace (continuous furnace) that can heat and hold at a temperature of 500 °C or more and 650 °C or less for several minutes. In addition, the softening annealing is not limited to being carried out in a continuous furnace, and the composite material 40 can also be placed in an intermittent furnace. The stamping blank 51 may be in any form that can be stamped. For example, it may be in the form of a long strip, or it may be in the form of a rectangle obtained by cutting the composite material 40 into a specified size.

[0088] In the process of stamping the stamping blank 51, the stamping blank 51 is stamped so as to form a flange portion 12, a shaft portion 11, and a recessed portion 13. The shaft portion 11 extends from the flange portion 12 in the stacking direction (Z direction) of the Al layer 41 and the Cu layer 42, and the recessed portion 13 is located at the end on the Cu layer 42 side (Z2 side) of the shaft portion 11 and has a surface made of the Cu layer 42.

[0089] In the process of stamping the stamping blank 51, as Figure 8 shown, the shape of the stamping blank 51 is formed into the shape of the negative electrode terminal 10 by performing multiple stamping processes. Specifically, by performing multiple stamping processes shown in (b) of Figure 8 to Figure 8 shown in (d) of Figure 8The shape of the blank 51 for stamping shown in (a) is formed into the shape of the negative electrode terminal 10, where the negative electrode terminal 10 has a flange portion 12, a shaft portion 11 extending from the flange portion 12 toward the Z2 side in the stacking direction of the Cu layer 42 and the Al layer 41, and a recessed portion 13. For example, first, the blank 51 for stamping is disposed in the cavity of the die of a stamping machine. At this time, the Cu layer 42 of the blank 51 for stamping is disposed on the Z2 side in the cavity of the die such that the outer surfaces of the shaft portion 11 and the recessed portion 13 of the negative electrode terminal 10 are formed by the Cu layer 42. The cavity of this die has a cavity shape for forming an intermediate stage shape that reaches the final shapes of the shaft portion 11, the flange portion 12, and the recessed portion 13 of the negative electrode terminal 10.

[0090] Next, the blank 51 for stamping is stamped mainly from the Z1 side toward the Z2 side. Through this first-stage stamping, as Figure 8 shown in (b), the Cu layer 42 extends toward the Z2 side in the stacking direction (Z direction), and the Al layer 41 follows the Cu layer 42 and extends toward the Z2 side, thereby forming the original shape of the shaft portion 11. In addition, the original shape of the flange portion 12 is formed by the portions of the Al layer 41 and the Cu layer 42 that do not extend toward the Z2 side.

[0091] Next, the front end of the shaft portion 11 in the original shape is stamped mainly upward (Z1 side) in the direction opposite to that when the shaft portion 11 is formed. Through this second-stage stamping, as Figure 8 shown in (c), the original shape of the recessed portion 13 having a surface formed by the Cu layer 42 is formed at the end portion on the Cu layer 42 side (Z2 side) of the shaft portion 11.

[0092] Next, the recessed portion 13 in the original shape is stamped mainly toward the Z1 side to form the recessed portion 13 to a greater depth. Through this third-stage stamping, as Figure 8 shown in (d), it is formed into the shape of the negative electrode terminal 10. That is, it is formed into the shape of the negative electrode terminal 10 having a flange portion 12, a shaft portion 11 extending from the flange portion 12 toward the Z2 side in the stacking direction of the Cu layer 42 and the Al layer 41, and a recessed portion 13 located at the front end on the Z2 side of the shaft portion 11 and having a surface formed by the Cu layer 42. After this stamping, the Al layer 41 preferably has a Vickers hardness of 55 HV or more, more preferably has a Vickers hardness of 66 HV or more, still more preferably has a Vickers hardness of 66 HV or more and 102 HV or less, and most preferably has a Vickers hardness of 66 HV or more and 73 HV or less.

[0093] (Method for manufacturing a battery)

[0094] The lithium-ion battery 1 is constructed by arranging a power generation element 4 composed of a positive electrode 4a, a negative electrode 4b, and a separator 4c, a negative electrode current collector 5, and a positive electrode current collector 6 in a can member 3 filled with an electrolyte 30, and then installing a lid member 2. At this time, a seal 7 and a negative electrode terminal 10 are inserted into the lid member 2, and the concave portion 13 of the negative electrode terminal 10 is fixed to the negative electrode current collector 5 by riveting. Similarly, a seal 8 and a positive electrode terminal 20 are inserted into the lid member 2, and the concave portion 23 is fixed to the positive electrode current collector 6 by riveting. Then, a battery pack 100 is constructed by connecting a plurality of lithium-ion batteries 1 using a bus bar 101.

[0095] <Effect of the present embodiment>

[0096] The following effects can be obtained in the present embodiment.

[0097] In the battery terminal (negative electrode terminal 10) of the present embodiment, the Al layer 41 is made of an Al alloy containing Mn or Mg. As a result, the hardness of the Al layer 41 is greater than that of an Al layer made of pure Al. Therefore, compared with an Al layer made of pure Al, a decrease in the hardness of the Al layer 41 when annealing softens the Cu layer 42 made of Cu can be suppressed. In the case of a process of performing stamping after annealing, compared with an Al layer made of pure Al, the hardness of the annealed Al layer 41 is greater. Therefore, excessive extension of the Al layer 41 can be suppressed. As a result, it is possible to suppress the Al layer 41 from piercing the Cu layer 42 on the surface of the side wall portion 13a forming the concave portion 13 and being exposed on the surface of the side wall portion 13a of the concave portion 13 due to the Al layer 41 extending more than the Cu layer 42. Thus, exposure of the Al layer 41 on the surface of the concave portion 13 can be suppressed. Therefore, it is possible to suppress the Al layer 41 from coming into contact with the electrolyte 30 and dissolving at the concave portion 13 riveted to the negative electrode current collector 5, thereby forming a gap at the concave portion 13, and it is possible to suppress a decrease in the electrical characteristics of the lithium-ion battery 1. In addition, the conductivity is 30% IACS or more, so the conductivity required for functioning as a battery terminal (negative electrode terminal 10) can be ensured. In this regard, the electrical characteristics of the lithium-ion battery 1 can also be maintained. As a result, it is possible to provide a battery terminal (negative electrode terminal 10) that can suppress exposure of the Al layer 41 in a portion (especially the side wall portion 13a of the concave portion 13 that becomes a thin wall) that requires the surface to be made of the Cu layer 42 while maintaining the electrical characteristics of the lithium-ion battery 1.

[0098] In the battery terminal (negative electrode terminal 10) of the present embodiment, the Al alloy has a conductivity of 40% IACS or more. As a result, the conductivity required for functioning as a battery terminal (negative electrode terminal 10) can be sufficiently ensured.

[0099] In the battery terminal (negative electrode terminal 10) of the present embodiment, the Al alloy contains Al with the highest content and Mn with the second highest content. The Al layer 41 made of the Al alloy containing Al with the highest content and Mn with the second highest content has a reduced hardness compared to the Al layer made of the Al alloy containing Al with the highest content and Mg with the second highest content. Therefore, the Al layer 41 made of the Al alloy containing Al with the highest content and Mn with the second highest content can suppress the decrease in hardness caused by annealing compared to the Al layer made of pure Al. On the other hand, compared to the Al layer made of the Al alloy containing Al with the highest content and Mg with the second highest content, it can increase the decrease in hardness caused by annealing. Thus, the Al layer 41 made of the Al alloy containing Al with the highest content and Mn with the second highest content can suppress the Al layer 41 from extending too much compared to the Cu layer 42, and can improve the stamping processability compared to the Al layer made of the Al alloy containing Al with the highest content and Mg with the second highest content. In addition, the Al layer 41 made of the Al alloy containing Al with the highest content and Mn with the second highest content has a high conductivity compared to the Al layer made of the Al alloy with the second highest Mg content. Therefore, the conductivity required to function as a battery terminal (negative electrode terminal 10) can be sufficiently ensured. In this regard, the electrical characteristics of the lithium ion battery 1 can also be maintained. The inventors of the present application have learned about the above aspects through the examples (simulations) described below.

[0100] In the manufacturing method of the battery terminal (negative electrode terminal 10) according to the present embodiment, it includes a step of preparing a composite material 40 obtained by diffusion bonding an Al layer 41 made of an Al alloy and a Cu layer 42 made of Cu in the stacking direction. Among them, the Al alloy contains the most abundant Al and the second most abundant Mn or Mg and has a conductivity of 30% IACS or more. Thus, the Vickers hardness of the Al layer 41 is 30 HV or more, so it is possible to suppress the Al layer 41 from piercing the surface of the Cu layer 42 that constitutes the side wall portion 13a of the recess 13 and exposing it on the surface of the side wall portion 13a of the recess 13. Regarding this effect, the inventors of the present application have learned through the following examples (simulations). Thus, it is possible to suppress the Al layer 41 from being exposed on the surface of the side wall portion 13a of the recess 13. Therefore, it is possible to suppress the electrolyte 30 from contacting the exposed Al layer 41 and forming a gap in the Al layer 41, thereby suppressing the deterioration of the electrical characteristics of the lithium-ion battery 1. In addition, since the conductivity is 30% IACS or more, it is possible to ensure the conductivity required to function as a battery terminal (negative electrode terminal 10). In this regard, the electrical characteristics of the lithium-ion battery 1 can also be maintained. As a result, it is possible to manufacture a battery terminal (negative electrode terminal 10) that can suppress the exposure of the Al layer 41 in the portion where the surface needs to be formed by the Cu layer 42 (especially the side wall portion 13a of the recess 13 that becomes a thin wall) while maintaining the electrical characteristics of the lithium-ion battery 1.

[0101] In the manufacturing method of the battery terminal (negative electrode terminal 10) according to the present embodiment, in the step of tempering into a blank 51 for stamping, the Vickers hardness of the Al layer 41 is tempered to 30 HV or more and 75 HV or less, and the Vickers hardness of the Cu layer 42 is tempered to 50 HV or more and 80 HV or less. Thus, it is possible to suppress the Al layer 41 from piercing the surface of the Cu layer 42 that constitutes the side wall portion 13a of the recess 13 and exposing it on the surface of the side wall portion 13a of the recess 13 during stamping. Regarding this effect, the inventors of the present application have learned through the following examples (simulations).

[0102] In the manufacturing method of the battery terminal (negative electrode terminal 10) according to the present embodiment, in the step of preparing the composite material 40, the Al layer 41 made of an Al alloy having a conductivity of 40% IACS or more and the Cu layer 42 made of Cu are diffusion bonded in the stacking direction to prepare the composite material. Since the Al layer 41 is made of an Al alloy having a conductivity of 40% IACS or more, the electrical characteristics of the lithium-ion battery 1 can be improved compared to the case of the Al layer made of an Al alloy having a conductivity of 30% IACS or more and less than 40% IACS.

[0103] In the battery (lithium-ion battery 1) of the present embodiment, it includes a battery terminal (negative electrode terminal 10), an electrolytic solution 30, a housing (lid member 2, can member 3) for storing the electrolytic solution 30, a positive electrode side member (positive electrode 4a, positive electrode current collector 6 composed of a connecting portion 6a, leg portions 6b, and a connecting plate 6c) for constituting the positive electrode side of the lithium-ion battery 1, a negative electrode side member (negative electrode 4b, negative electrode current collector 5 composed of a connecting portion 5a, leg portions 5b, and a connecting plate 5c) for constituting the negative electrode side of the lithium-ion battery 1, and a separator 4c for separating the positive electrode 4a and the negative electrode 4b of the lithium-ion battery 1. Among them, the battery terminal (negative electrode terminal 10) includes: a flange portion 12, which is formed by diffusion bonding an Al layer 41 made of an Al alloy and a Cu layer 42 made of Cu in the stacking direction. The Al alloy contains the most Al and the second most Mn or Mg and has a conductivity of 30% IACS or more; and a shaft portion 11, which extends from the flange portion 12 toward the Z2 side in the stacking direction (Z direction) of the Al layer 41 and the Cu layer 42. The concave portion 13 of the battery terminal (negative electrode terminal 10) is fixed to the negative electrode side member by riveting. As described above, the battery terminal (negative electrode terminal 10) can suppress the exposure of the Al layer 41 on the surface of the side wall portion 13a of the concave portion 13 while maintaining the electrical characteristics of the lithium-ion battery 1. Therefore, it can suppress the contact and dissolution of the Al layer 41 with the electrolytic solution 30 at the concave portion 13 of the battery terminal (negative electrode terminal 10) riveted to the negative electrode side member of the lithium-ion battery 1. Thereby, it can suppress the reduction of the electrical characteristics of the lithium-ion battery 1 due to the formation of a gap at the concave portion 13 of the battery terminal (negative electrode terminal 10). In addition, since the conductivity is 30% IACS or more, the conductivity required for the battery terminal (negative electrode terminal 10) to function can be ensured. In this regard, the electrical characteristics of the lithium-ion battery 1 can also be maintained. Since the battery terminal (negative electrode terminal 10) that can suppress the exposure of the Al layer 41 in the portion where the surface needs to be formed by the Cu layer 42 (especially the side wall portion 13a of the concave portion 13 that becomes a thin wall) is used, as a result, a battery (lithium-ion battery 1) that can suppress the reduction of electrical characteristics caused by the battery terminal (negative electrode terminal 10) while maintaining the electrical characteristics of the lithium-ion battery 1 can be provided.

[0104] In the manufacturing method of the battery (lithium-ion battery 1) according to this embodiment, the lithium-ion battery 1 includes a battery terminal (negative electrode terminal 10), an electrolytic solution 30, a housing (lid member 2, can member 3) for storing the electrolytic solution 30, a positive electrode side member (positive electrode 4a, positive electrode current collector 6 composed of a connecting portion 6a, leg portions 6b, and a connecting plate 6c, positive electrode terminal 20) for constituting the positive electrode side of the lithium-ion battery 1, a negative electrode side member (negative electrode 4b, negative electrode current collector 5 composed of a connecting portion 5a, leg portions 5b, and a connecting plate 5c, negative electrode terminal 10) for constituting the negative electrode side of the lithium-ion battery 1, and a separator 4c for separating the positive electrode and the negative electrode of the lithium-ion battery 1. Among them, the battery terminal (negative electrode terminal 10) includes: a flange portion 12 formed by diffusion bonding an Al layer 41 made of an Al alloy and a Cu layer 42 made of Cu in the stacking direction. The Al alloy contains the most abundant Al and the second most abundant Mn or Mg and has a conductivity of 30% IACS or more; a shaft portion 11 extending from the flange portion 12 toward the Z2 side in the stacking direction (Z direction) of the Al layer 41 and the Cu layer 42; and a recess 13 located at the end of the shaft portion 11 on the Cu layer 42 side (Z2 side) and having a surface formed by the Cu layer 42. The manufacturing method of the lithium-ion battery 1 includes a step of fixing the recess 13 of the battery terminal (negative electrode terminal 10) to the negative electrode side member by riveting. As described above, the battery terminal (negative electrode terminal 10) can suppress the exposure of the Al layer 41 on the surface of the side wall portion 13a of the recess 13 while maintaining the electrical characteristics of the lithium-ion battery 1. Therefore, it is possible to suppress the Al layer 41 from coming into contact with the electrolytic solution 30 and dissolving at the recess 13 of the battery terminal (negative electrode terminal 10) riveted to the negative electrode side member of the lithium-ion battery 1. Thus, it is possible to suppress the reduction of the electrical characteristics of the lithium-ion battery 1 due to the formation of a gap at the recess 13 of the battery terminal (negative electrode terminal 10). In addition, since the conductivity is 30% IACS or more, the conductivity required for the battery terminal (negative electrode terminal 10) to function can be ensured. In this regard, the electrical characteristics of the lithium-ion battery 1 can also be maintained. Since the battery terminal (negative electrode terminal 10) that can suppress the exposure of the Al layer 41 in a portion where the surface needs to be formed by the Cu layer 42 (especially the side wall portion 13a of the recess 13 that becomes a thin wall) is used, as a result, it is possible to manufacture a lithium-ion battery 1 that can suppress the reduction of electrical characteristics caused by the battery terminal negative electrode terminal 10 while maintaining the electrical characteristics of the lithium-ion battery 1.

[0105] [Embodiment]

[0106] Next, with reference to Figures 9 - 16 , the CAE (Computer Aided Engineering) simulation of the battery terminal (negative electrode terminal 10) according to the above embodiment and its results will be described. In addition, inFigures 9 - 16 In [the figure], a cross-sectional view obtained by slicing the negative electrode terminal 10 in the Z direction in a manner passing through the central axis is shown, with the central axis being the center of the cylindrical shaft portion 11 of the battery terminal (negative electrode terminal 10).

[0107] In this CAE simulation, as Example 1, a composite material 40 composed of an Al layer 41 and a Cu layer 42 was set. Among them, the Al layer 41 was composed of an Al alloy (hereinafter referred to as "A3003") equivalent to A3003, which is one of the well-known Al-Mn series Al alloys. This Al alloy contains the most abundant Al and the second most abundant Mn. The Cu layer 42 was composed of Cu (hereinafter simply referred to as "C1020") equivalent to C1020, which is one of the well-known pure Cu. As Example 2, a composite material 40 composed of an Al layer 41 and a Cu layer 42 was set. Among them, the Al layer 41 was composed of an Al alloy (hereinafter simply referred to as "A5052") equivalent to A5052, which is one of the well-known Al-Mg series Al alloys. This Al alloy contains the most abundant Al and the second most abundant Mg. The Cu layer 42 was composed of Cu equivalent to C1020. As a comparative example, a composite material 40 composed of an Al layer 41 and a Cu layer 42 was set. Among them, the Al layer 41 was composed of Al (hereinafter simply referred to as "A1050") equivalent to A1050, which is one of the well-known pure Al, and the Cu layer 42 was composed of Cu equivalent to C1020.

[0108] In this CAE simulation, using the composite materials 40 of Example 1, Example 2, and Comparative Example 1, the plastic deformation progression of the Al layer 41 and the Cu layer 42 that make up the composite material 40 was analyzed in the case of manufacturing the negative electrode terminal 10 by stamping (forging), and the Vickers hardness was obtained based on the analysis values obtained during the analysis. Among them, stamping (forging) is divided into first stamping forming, second stamping forming, and third stamping forming. In addition, the software used for the CAE simulation is DEFORM produced by SFTC (Scientific Forming Technologies Corporation). Regarding the simulation conditions, the sparse matrix method (SPOOLES) was used as the solver, and the Newton-Raphson method was used as the iterative method. Among them, the unit is the SI unit, the object temperature is 20°C, the ambient temperature is 20°C, there is no heat transfer, the interface between the Al layer 41 and the Cu layer 42 is in close contact (no interface separation), and the tool movement speed (stamping speed) is 10 mm / sec. In addition, the physical property values shown in Table 1 were assigned to the materials for CAE analysis. Among them, the hardness ratio compared with A1050 shown in Table 1 is not the physical property value assigned to the materials for CAE analysis, but a reference value. The hardness ratios of A3003 and A5052 compared with A1050 are calculated values obtained by dividing the hardness of A3003 by the hardness of A1050 and dividing the hardness of A5052 by the hardness of A1050.

[0109] [Table 1]

[0110]

[0111] As shown in Table 1, at the start of the first stamping forming, the Vickers hardness of the Al layer 41 was 39 HV in Example 1, 59 HV in Example 2, and 25 HV in the comparative example. In addition, the Vickers hardness of the Cu layer 42 was 54 HV in all of Example 1, Example 2, and the comparative example. In addition, the hardness ratio of A3003 compared with A1050 was +1.6, and the hardness ratio of A5052 compared with A1050 was +2.4. Among them, the Vickers hardness of the materials shown in Table 1 is the measured value.

[0112] In addition, at the start of the first stamping forming, the fracture strength of the Al layer 41 was 123 MPa in Example 1, 209 MPa in Example 2, and 81 MPa in the comparative example. In addition, the fracture strength of the Cu layer 42 was 233 MPa in all of Example 1, Example 2, and the comparative example. Among them, the fracture strength of the materials shown in Table 1 is the measured value.

[0113] In addition, at the start of the first stamping, the elongation rate of the Al layer 41 was 34% in Example 1, 16% in Example 2, and 36% in the comparative example. In addition, the elongation rate of the Cu layer 42 was 45% in both Example 1, Example 2, and the comparative example. Among them, the elongation rates of the materials shown in Table 1 are measured values.

[0114] In addition, at the start of the first stamping, the conductivity of the Al layer 41 was 50% IACS in Example 1, 35% IACS in Example 2, and 62% IACS in the comparative example. In addition, the conductivity of the Cu layer 42 was 101% IACS in both Example 1, Example 2, and the comparative example. Among them, the conductivity of the materials shown in Table 1 is a general literature value.

[0115] As Figure 9 shown, the first stamping in the CAE simulation is a process of stamping a composite material (before processing) to form a first formed body (after processing) having a shaft portion 11 as shown in (b) of Figure 8 . Through the first stamping, in the first formed bodies of Example 1, Example 2, and the comparative example, the front end portions of the Al layer 41 extending and deforming toward the Cu layer 42 as indicated by the arrows all reach substantially the same position, and no clear differences are seen.

[0116] The second stamping in the CAE simulation is carried out immediately after the first stamping. As Figure 10 shown, the second stamping is a process of stamping the first formed body (before processing) formed by the first stamping to form a second formed body (after processing) having a recess 13 as shown in (c) of Figure 8 . In addition, the depth of the recess 13 of the second formed body is shallower than the depth of the recess 13 of the third formed body formed by the subsequent third stamping. Through the second stamping immediately following the first stamping, differences can be seen in the morphology of the front end portions of the Al layer 41 extending and deforming further toward the Cu layer 42 as indicated by the arrows in the second formed bodies of Example 1, Example 2, and the comparative example. Specifically, in the second formed bodies of Example 1 and the comparative example, the morphology of the front end portions of the Al layer 41 extending and deforming further toward the Cu layer 42 as indicated by the arrows is substantially the same, becoming a slightly protruding morphology. On the other hand, in the second formed body of Example 2, the front end portion of the Al layer 41 extending and deforming further toward the Cu layer 42 as indicated by the arrow is a non-protruding morphology, becoming a morphology different from that of Example 1 and the comparative example.

[0117] The third stamping in the CAE simulation is carried out immediately after the second stamping. As Figure 11 shown, the third stamping is a process of stamping the second formed body (before processing) formed by the second stamping to form a...Figure 8 The process of forming a third molded body (after processing) with the recess 13 shown in (d). The depth of the recess 13 of the third molded body corresponds to the depth of the recess 13 of the battery terminal (negative terminal 10). By the third stamping immediately after the second stamping, the difference can be seen in the morphology of the front end portion of the Al layer 41 shown by the arrow that is further extended to the Cu layer 42 side and deformed in the third molded bodies of Example 1, Example 2 and the comparative example. Specifically, in the third molded bodies of Example 1 and the comparative example, the front end portion shown by the arrow that is further extended to the Cu layer 42 side and deformed is in the form of a sharp protrusion (refer to Figure 11 On the other hand, in the third molded body of Example 2, the front end portion of the Al layer 41 further extended toward the Cu layer 42 and deformed as indicated by the arrow is slightly protruding (see Figure 10 The enclosed portion shown in FIG5 is different from that of Example 1 and the comparative example.

[0118] like Figure 12 As shown, when the front end portion of the Al layer 41 further extended and deformed toward the Cu layer 42 is magnified and observed, as shown in FIG. Figure 12 As shown in the first enlarged view, in the third molded body of Example 2, the front end portion of the Al layer 41 that is further extended toward the Cu layer 42 side and deformed does not protrude in a sharp shape. In the third molded bodies of Example 1 and the comparative example, the front end portion of the Al layer 41 that is further extended toward the Cu layer 42 side and deformed protrudes in a sharp shape. However, when comparing the positions of the front end portion of the Al layer 41 that is further extended toward the Cu layer 42 side and deformed, in the third molded body of Example 1, it does not reach the surface on the inner side of the side wall portion 13a of the recess 13, while in the third molded body of the comparative example, it reaches the surface on the inner side of the side wall portion 13a of the recess 13. According to the difference in the morphology, as Figure 12 As shown in the second enlarged view, in the third molded body of the comparative example, the Al layer 41 pierces the Cu layer 42 on the inner surface of the side wall portion 13a of the recess 13, and the Al layer 41 is exposed on the inner surface of the side wall portion 13a of the recess 13.

[0119] Here, as a reference example, Figure 13 . Figure 13 This photograph shows a cross-section taken along the Z direction, obtained by stamping a composite material into a real battery terminal. The composite material is composed of an Al layer 41 made of Al050 and a Cu layer 42 made of C1020. This composite material corresponds to the composite material of the comparative example simulated using CAE. Figure 13The cross-sectional part of the battery terminal of the physical object shown corresponds to Figure 12 the cross-sectional part of the third molded body of the CAE simulation shown in the second enlarged view of Figure 13 As shown, in the case of using the composite material corresponding to the comparative example, in the battery terminal of the physical object, it can be confirmed that the Al layer 41 pierces the Cu layer 42 on the inner surface of the side wall part 13a constituting the recess 13, and the Al layer 41 is exposed on the inner surface of the side wall part 13a of the recess 13. In addition, it can be confirmed that Figure 13 the shape of the sharp protrusion at the front end of the deformed and extended Al layer 41 shown is approximately similar to Figure 12 the shape of the sharp protrusion at the front end of the deformed and extended Al layer 41 shown in the second enlarged view of

[0120] From the above CAE simulation, it can be known that in the composite material 40 (Example 1) composed of the Al layer 41 made of A3003 and the Cu layer 42 made of C1020, the possibility that the Al layer 41 is not exposed on the surface of the side wall part 13a of the recess 13 is high. In addition, it can be known that compared with Example 1, in the composite material 40 (Example 2) composed of the Al layer 41 made of A5052 and the Cu layer 42 made of C1020, the possibility that the Al layer 41 is not exposed on the surface of the side wall part 13a of the recess 13 is higher. In addition, it can be known that in the composite material 40 (comparative example) composed of the Al layer 41 made of A1050 and the Cu layer 42 made of C1020, the Al layer 41 may be exposed on the surface of the side wall part 13a of the recess 13. Therefore, it can be known that different from the comparative example using pure Al (A1050), in Examples 1 and 2 using Al alloys (A3003, A5052), the exposure of the Al layer 41 on the surface of the side wall part 13a of the recess 13 can be suppressed.

[0121] In addition, it can be known that compared with Example 1 using A3003, in Example 2 using A5052, the amount of deformation (flow) of the extension of the Al layer 41 caused by stamping can be suppressed. Therefore, from the viewpoint of further suppressing the extension of the Al layer 41 during stamping, it is preferable that the Al layer 41 is composed of A5052 (A5000 series) which is harder than A3003 (A3000 series).

[0122] Furthermore, it is known that, compared with the Al layer 41 made of A5052 (Example 1) and the Al layer 41 made of A3003 (Example 2), where there is a high possibility that the Al layer 41 is not exposed on the inner surface of the side wall portion 13a of the concave portion 13 during stamping, in order to improve the electrical characteristics of the battery terminal (negative terminal 10), the conductivity of the Al layer 41 can be further increased. Therefore, from the perspective of improving electrical characteristics, it is preferable that the Al layer 41 is made of A3003 (A3000 series) which has a higher conductivity than A5052 (A5000 series).

[0123] Figures 14 - 16 Indicates the positions (10 positions of P1 to P10) of the third molded bodies of Example 1, Example 2, and the Comparative Example, where the Vickers hardness is obtained through CAE simulation. Among them, the third molded body of the CAE simulation corresponds to the battery terminal (negative terminal). In addition, for Figure 13 the physical battery terminal (Reference Example) shown, the Vickers hardness is also actually measured at positions (10 positions of P1 to P10) that are roughly the same as those in the case of the Comparative Example shown Figure 16 .

[0124] Table 2 shows the Vickers hardness at the positions of P1 to P10 shown for the third molded body obtained through CAE simulation, and also shows the average value of the Vickers hardness of the physical battery terminal (Reference Example) and the value obtained by subtracting the Vickers hardness of the Comparative Example from that of the Reference Example (the difference from CAE). Figures 14 - 16

[0125] [Table 2]

[0126]

[0127] In addition, Table 3 shows the ratio of the Vickers hardness of Example 1 to that of the Comparative Example (Example 1 / Comparative Example) and the ratio of the Vickers hardness of Example 2 to that of the Comparative Example (Example 2 / Comparative Example) obtained based on the Vickers hardness of Example 1, Example 2, and the Comparative Example of the third molded body shown in Table 2.

[0128] [Table 3]

[0129]

[0130] <Vickers hardness of P1>

[0131] As Figures 14 - 16 ​As shown, in the third molded body, P1 is the Al layer 41 on the front end side of the flange portion 12. The Vickers hardness of P1 was 49 HV in the comparative example, 66 HV which is about 1.3 times that of the comparative example (Example 1 / Comparative Example) in Example 1, and 97 HV which is about 2.0 times that of the comparative example (Example 2 / Comparative Example) in Example 2. In addition, the difference between the reference example (physical battery terminal) with a Vickers hardness of 46 HV and the comparative example (CAE) for P1 was about -3 HV. Also, in the composite material 40 before stamping, the Vickers hardness of the Al layer 41 was 25 HV for A1050 (comparative example), 39 HV which is about 1.6 times that of A1050 in Example 1 (refer to Table 1), and 59 HV which is about 2.4 times that of A1050 in Example 2 (refer to Table 1). As a result, at the position of P1, the difference trend of the Vickers hardness after stamping (third molded body) (Example 2 > Example 1 > Comparative Example) is the same as the difference trend of the Vickers hardness before stamping (composite material 40) (Example 2 > Example 1 > Comparative Example). Also, as shown in Table 2, the difference in Vickers hardness between the comparative example and the reference example (the difference from CAE) was -3 HV, which is slight. Thus, it can be considered that the Vickers hardness at the position of P1 also shows the same trend in actual stamping processing.

[0132] <Vickers hardness of P2>

[0133] As Figures 14 - 16 shown, in the third molded body, P2 is the Al layer 41 on the Z1 side near the central axis of the flange portion 12 and near the central axis of the shaft portion 11. The Vickers hardness of P2 was 53 HV in the comparative example, 72 HV which is about 1.4 times that of the comparative example (Example 1 / Comparative Example) in Example 1, and 102 HV which is about 1.9 times that of the comparative example (Example 2 / Comparative Example) in Example 2. In addition, the difference between the reference example (physical battery terminal) with a Vickers hardness of 47 HV and the comparative example (CAE) for P2 was about -6 HV. As a result, at the position of P2, similar to the position of P1, the difference trend of the Vickers hardness after stamping (third molded body) (Example 2 > Example 1 > Comparative Example) is the same as the difference trend of the Vickers hardness before stamping (composite material 40) (Example 2 > Example 1 > Comparative Example). Also, as shown in Table 2, the difference in Vickers hardness between the comparative example and the reference example was -6 HV, which is slight. Thus, it can be considered that the Vickers hardness at the position of P2 also shows the same trend as that at the position of P1 in actual stamping processing.

[0134] <Vickers hardness of P3>

[0135] As Figures 14 - 16As shown, in the third molded body, P3 is located in the Al layer 41 at the boundary between the flange portion 12 and the shaft portion 11, and near the boundary with the Cu layer 42. The Vickers hardness of P3 was 53 HV in the comparative example, and in Example 1 it was 73 HV, which is approximately 1.4 times that of the comparative example (Example 1 / Comparative Example), and in Example 2 it was 102 HV, which is approximately 1.9 times that of the comparative example (Example 2 / Comparative Example). In addition, the difference between the reference example (physical battery terminal) with a Vickers hardness of 52 HV for P3 and the comparative example (CAE) was approximately -1 HV. As a result, at the position of P3, similar to the positions of P1 and P2, the difference trend of the Vickers hardness after stamping (third molded body) (Example 2 > Example 1 > Comparative Example) was the same as the difference trend of the Vickers hardness before stamping (composite material 40) (Example 2 > Example 1 > Comparative Example). Also, as shown in Table 2, the difference in Vickers hardness between the comparative example and the reference example was -1 HV, which is slight. From this, it can be considered that the Vickers hardness at the position of P3, similar to the positions of P1 and P2, also shows the same trend in actual stamping.

[0136] <Vickers Hardness of P4>

[0137] As Figures 14 - 16 shown, in the third molded body, P4 is located in the Al layer 41 near the central axis of the shaft portion 11 on the Z2 side of P2, and near the center in the Z direction of the portion of the shaft portion 11 other than the concave portion 13. The Vickers hardness of P4 was 50 HV in the comparative example, and in Example 1 it was 69 HV, which is approximately 1.4 times that of the comparative example (Example 1 / Comparative Example), and in Example 2 it was 101 HV, which is approximately 2.0 times that of the comparative example (Example 2 / Comparative Example). In addition, the difference between the reference example (physical battery terminal) with a Vickers hardness of 46 HV for P4 and the comparative example (CAE) was approximately -4 HV. As a result, at the position of P4, similar to the positions of P1 to P3, the difference trend of the Vickers hardness after stamping (third molded body) (Example 2 > Example 1 > Comparative Example) was the same as the difference trend of the Vickers hardness before stamping (composite material 40) (Example 2 > Example 1 > Comparative Example). Also, as shown in Table 2, the difference in Vickers hardness between the comparative example and the reference example was -4 HV, which is slight. From this, it can be considered that the Vickers hardness at the position of P4, similar to the positions of P1 to P3, also shows the same trend in actual stamping.

[0138] <Vickers Hardness of P5>

[0139] As Figures 14 - 16As shown, in the third molded body, P5 is located on the Z2 side of the portion of the shaft portion 11 other than the concave portion 13 and near the side wall portion 13a of the concave portion 13, and is the Al layer 41. The Vickers hardness of P5 is 54 HV in the comparative example, and in Example 1 it is 73 HV, which is about 1.4 times that of the comparative example (Example 1 / Comparative Example), and in Example 2 it is 101 HV, which is about 1.9 times that of the comparative example (Example 2 / Comparative Example). In addition, the difference between the reference example (physical battery terminal) with a Vickers hardness of 53 HV and the comparative example (CAE) for P5 is about -1 HV. As a result, at the position of P5, similar to the positions of P1 to P4, the difference trend of the Vickers hardness after stamping (third molded body) (Example 2 > Example 1 > Comparative Example) is the same as the difference trend of the Vickers hardness before stamping (composite material 40) (Example 2 > Example 1 > Comparative Example). Also, as shown in Table 2, the difference in Vickers hardness between the comparative example and the reference example is -1 HV, which is slight. From this, it can be considered that the Vickers hardness at the position of P5 also shows the same trend in actual stamping as the positions of P1 to P4.

[0140] <Vickers Hardness of P6>

[0141] As Figures 14 - 16 shown, in the third molded body, P6 is located in the Cu layer 42 on the front end side of the flange portion 12 at a position closer to the Z2 side than P1. The Vickers hardness of P6 is 126 HV in the comparative example, and in Example 1 it is 126 HV, which is about 1.0 times that of the comparative example (Example 1 / Comparative Example), and in Example 2 it is 128 HV, which is about 1.0 times that of the comparative example (Example 2 / Comparative Example). In addition, 126 HV of the comparative example is about 2.3 times (126 HV / 54 HV) compared to before stamping (composite material 40). Also, the difference between the reference example (physical battery terminal) with a Vickers hardness of 125 HV and the comparative example (CAE) for P6 is about -1 HV. As a result, at the position of P6, the Vickers hardness after stamping (third molded body) is substantially the same as the Vickers hardness before stamping (composite material 40) (54 HV) (about 2.3 times), and the Vickers hardness of Example 1, Example 2, and the comparative example after stamping (third molded body) is substantially the same. Also, as shown in Table 2, the difference in Vickers hardness between the comparative example and the reference example is -1 HV, which is slight. From this, it can be considered that the Vickers hardness at the position of P6 also shows the same trend in actual stamping.

[0142] <Vickers Hardness of P7>

[0143] As Figures 14 - 16As shown, in the third molded body, the Cu layer 42 at the boundary between the flange portion 12 and the shaft portion 11 where P7 is located on the Z2 side of P3. The Vickers hardness of P7 was 133 HV in the comparative example, and in Example 1 it was 133 HV, which was about 1.0 times that of the comparative example (Example 1 / Comparative Example), and in Example 2 it was 133 HV, which was about 1.0 times that of the comparative example (Example 2 / Comparative Example). In addition, the 133 HV of the comparative example was about 2.5 times (133 HV / 54 HV) compared to before stamping (composite material 40). In addition, the difference between the reference example (actual battery terminal) with a Vickers hardness of 134 HV and the comparative example (CAE) at P7 was about +1 HV. As a result, at the position of P7, the Vickers hardness after stamping (third molded body) was approximately the same (about 2.5 times) as the Vickers hardness before stamping (composite material 40), and the Vickers hardness of Example 1, Example 2, and the comparative example after stamping (third molded body) was approximately the same. In addition, as shown in Table 2, the difference in Vickers hardness between the comparative example and the reference example was +1 HV, which was slight. It can be considered that the Vickers hardness at the position of P7 also showed the same trend in actual stamping as at the position of P6.

[0144] <Vickers Hardness of P8>

[0145] As Figures 14 - 16 shown, in the third molded body, P8 is located in the Cu layer 42 near the central axis of the shaft portion 11 on the Z2 side of P4, and is near the center of the bottom portion (Z1 side) of the concave portion 13 of the shaft portion 11. The Vickers hardness of P8 was 123 HV in the comparative example, and in Example 1 it was 128 HV, which was about 1.0 times that of the comparative example (Example 1 / Comparative Example), and in Example 2 it was 132 HV, which was about 1.1 times that of the comparative example (Example 2 / Comparative Example). In addition, the 123 HV of the comparative example was about 2.3 times (123 HV / 54 HV) compared to before stamping (composite material 40). In addition, the difference between the reference example (actual battery terminal) with a Vickers hardness of 110 HV and the comparative example (CAE) at P8 was about -13 HV. As a result, at the position of P8, the Vickers hardness after stamping (third molded body) was approximately the same (about 2.3 times) as the Vickers hardness before stamping (composite material 40), and the Vickers hardness of Example 1, Example 2, and the comparative example after stamping (third molded body) was approximately the same. In addition, as shown in Table 2, the difference in Vickers hardness between the comparative example and the reference example was -13 HV, which was slightly larger, but considering that it was the end of the Cu layer 42 far from the boundary with the Al layer 41, it was considered acceptable. It can be considered that the Vickers hardness at the position of P8 also showed the same trend in actual stamping as at the positions of P6 and P7.

[0146] <Vickers hardness of P9>

[0147] As shown Figures 14 - 16 In the third molded body, P9 is located at the boundary between the shaft portion 11 and the side wall portion 13a forming the concave portion 13, and near the inside of the side wall portion 13a, in the Cu layer 42. The Vickers hardness of P9 was 133 HV in the comparative example, and 133 HV which was about 1.0 times that of the comparative example (Example 1 / Comparative Example) in Example 1, and 133 HV which was about 1.0 times that of the comparative example (Example 2 / Comparative Example) in Example 2. In addition, 133 HV of the comparative example was about 2.5 times (133 HV / 54 HV) compared with before stamping (composite material 40). In addition, the difference between the reference example (physical battery terminal) with a Vickers hardness of 127 HV and the comparative example (CAE) for P9 was about -6 HV. As a result, at the position of P9, the Vickers hardness after stamping (third molded body) was substantially the same (about 2.5 times) as the Vickers hardness before stamping (composite material 40), and the Vickers hardnesses of Example 1, Example 2, and the comparative example after stamping (third molded body) were substantially the same. In addition, as shown in Table 2, the difference in Vickers hardness between the comparative example and the reference example was -6 HV, which was slight. From this, it can be considered that the Vickers hardness at the position of P9 also shows the same tendency as that at the positions of P6 to P8 in actual stamping.

[0148] <Vickers hardness of P10>

[0149] As shown Figures 14 - 16As shown, in the third molded body, P10 is located in the Cu layer 42 at the end on the Z2 side of the side wall portion 13a forming the concave portion 13. The Vickers hardness of P10 was 128 HV in the comparative example, 122 HV which was about 1.0 times (Example 1 / Comparative Example) compared with the comparative example in Example 1, and 120 HV which was about 0.9 times (Example 2 / Comparative Example) compared with the comparative example in Example 2. In addition, 128 HV of the comparative example was about 2.5 times (128 HV / 54 HV) compared with before stamping (composite material 40). Further, the difference between the reference example (physical battery terminal) with a Vickers hardness of 114 HV of P10 and the comparative example (CAE) was about -14 HV. As a result, at the position of P10, the Vickers hardness after stamping (third molded body) was substantially the same (about 2.5 times) as the Vickers hardness before stamping (composite material 40), and the Vickers hardnesses of Example 1, Example 2, and the comparative example after stamping (third molded body) were substantially the same. In addition, as shown in Table 2, the difference in Vickers hardness between the comparative example and the reference example was -14 HV, which was slightly large, but considering that it was the end of the Cu layer 42 far from the boundary with the Al layer 41, it was considered to be no problem. From this, it can be considered that the Vickers hardness at the position of P10 also shows the same trend in actual stamping as at the positions of P6 to P9.

[0150] As described above, the following results were obtained through CAE simulation: the difference trend of the Vickers hardness after stamping (third molded body) (Example 2 > Example 1 > Comparative Example) was the same as the difference trend of the Vickers hardness before stamping (composite material 40) (Example 2 > Example 1 > Comparative Example), so it can be considered that the same trend is also shown in actual stamping. From this, it can be considered that by appropriately setting the Vickers hardness of the Al layer 41 of the composite material 40 before stamping, the flow (plastic deformation) of the Al layer 41 caused by the Vickers hardness of the Al layer 41 in the battery terminal (negative terminal 10) after stamping can be controlled.

[0151] In addition, through CAE simulation, in the comparative example of the (third molded body) after stamping, a result was obtained that the Vickers hardness of the Al layer 41 (A1050) was less than 60 HV (49 HV to 54 HV), while in Example 1 of the (third molded body) after stamping, a result was obtained that the Vickers hardness of the Al layer 41 (A3003) was 60 HV or more (66 HV to 73 HV). In addition, Example 2 of the (third molded body) after stamping also similarly obtained a result that the Vickers hardness of the Al layer 41 (A5052) was 60 HV or more (97 HV to 102 HV). Therefore, it can be considered that compared with Example 1 and Example 2 of the (composite material 40) before stamping, the Al layer 41 in the comparative example of the (composite material 40) before stamping was soft and excessively extended during stamping. It can be considered that due to the excessive extension of the Al layer 41, the Al layer 41 that extended excessively compared with the Cu layer 42 pierced the Cu layer 42 that should form the surface, especially piercing the Cu layer 42 at the side wall portion 13a of the thin-walled concave portion 13 and exposing it on the surface.

[0152] In addition, the following results were obtained through CAE simulation: In Example 1 (A3003) and Example 2 (A5052) where the Vickers hardness of the Al layer 41 in the (composite material 40) before stamping was greater than that of the comparative example (A1050), the Al layer 41 did not pierce the Cu layer 42 and expose it on the surface. From this, it can be known that by forming the Al layer 41 from an Al alloy of the A3000 series or A5000 series containing the most Al and the second most Mn or Mg, it is possible to provide a battery terminal that can suppress the exposure of the Al layer 41 in a portion that needs to be formed by the Cu layer 42 (especially the side wall portion 13a of the thin-walled concave portion 13). In addition, as shown in Figure 11 after processing of, the following results were obtained: In Example 1 (A3003) where the Vickers hardness of the Al layer 41 in the (composite material 40) before stamping was greater than that of the comparative example (A1050) and less than that of Example 2 (A5052), the front end portion of the Al layer 41 did not pierce the Cu layer 42 and expose it on the surface, and the front end portion of the Al layer 41 extended more toward the Z2 side than Example 2 (A5052). Thus, from the viewpoint of stamping processability, it is preferable that the Vickers hardness of the Al layer 41 is smaller. Therefore, it can be known that it is preferable to form the Al layer 41 from an Al alloy of the A3000 series where the Vickers hardness of the Al layer 41 in the (composite material 40) before stamping is greater than that of the comparative example (A1050) and less than that of Example 2 (A5052).

[0153] Refer to Figures 17 - 19 and an additional CAE simulation and its results regarding the battery terminal (negative electrode terminal 10) of the above-described embodiment will be described. As shown in Figure 17As shown, in the CAE simulation, it is assumed that the pre-formed composite material 40 is subjected to the first stamping, the second stamping, and the third stamping to fabricate the formed battery terminal having the shaft portion 11 and the concave portion 13.

[0154] As Figure 18 shown, in the additional CAE simulation, in addition to the above-described Example 1, Example 2, and Comparative Example, as Example 3, a composite material 40 composed of an Al layer 41 and a Cu layer 42 was set. Among them, the Al layer 41 is composed of an Al alloy equivalent to A5083, which is one of the well-known Al-Mn-based Al alloys (hereinafter referred to as "A5083"). This Al alloy contains the most abundant Al and the second most abundant Mn, and the Cu layer 42 is composed of C1020.

[0155] The software used in this CAE simulation is DEFORM produced by SFTC. Regarding the simulation conditions, the sparse matrix method (SPOOLES) is used as the solver, and the Newton-Raphson method is used as the iterative method. Among them, the unit is the SI unit, the object temperature is 20°C, the ambient temperature is 20°C, there is no heat transfer, the interface between the Al layer 41 and the Cu layer 42 is in close contact (no interface separation), and the tool movement speed (stamping speed) is 10 mm / sec.

[0156] In addition, as Figure 19 shown, the length from the bottom surface of the concave portion 13 to the front end of the Al layer 41, that is, the elongation degree LA of Al, and the minimum thickness ΔTA of the Cu layer 42 located between the concave portion 13 and the Al layer 41 are measured.

[0157] Figure 18 is a diagram with the state before the third stamping as the state before processing and the state after the third stamping as the state after processing. In addition, this CAD is Figure 11 different, and it is assumed that a battery terminal with a short shaft portion 11 as Figure 8 shown is formed. Therefore, the stamping conditions are different from those in Figure 11 . In addition, the enlarged view of the front end portion of the processed Al layer 41 is an enlarged view of the processed front end portion. The thickness of the Cu layer 42 with the minimum thickness in the portion surrounded by the quadrilateral in the enlarged view of the processed front end portion is measured and recorded as the predicted value of the minimum thickness of the Cu layer 42. In addition, the actual photo is Figure 19 the same. In addition, in Figure 18 , the measured value of the minimum thickness of the Cu layer 42 (the thickness of the arrow portion of the photo) is recorded in the column below the actual photo.

[0158] As Figure 18As shown, in Comparative Example 1, the predicted minimum thickness of the Cu layer 42 was 0.199 mm. In Example 1, the predicted minimum thickness of the Cu layer 42 was 0.144 mm. In Example 2, the predicted minimum thickness of the Cu layer 42 was 0.195 mm. In Example 3, the predicted minimum thickness of the Cu layer 42 was 0.549 mm. The smaller the value of the part with the minimum thickness of the Cu layer 42, the closer the Al layer 41 is to the inner surface (concave portion 13) of the Cu layer 42, and the greater the possibility that the Al layer 41 is exposed to the outside. Therefore, it can be said that in the comparative example where the value of the part with the minimum thickness of the Cu layer 42 is small, the possibility that the Al layer 41 protrudes to the outside is high. In addition, it is known that compared with other examples, in Example 3, the value of the part with the minimum thickness of the Cu layer 42 is large, and it is difficult for the Al layer 41 to be exposed.

[0159] In addition, as Figure 19 shown, compared with Comparative Example 1, the degree of elongation of the Cu layer 42 in Example 1 became larger. It is considered that this is because it varies according to the molding conditions (for example, transfer molding method, pressing force, difference in the gap between the molded body and the mold surface, etc.), so there are cases where it becomes larger compared with the comparative example. On the other hand, as Figure 18 shown, the measured value of the minimum thickness of the Cu layer 42 was 0.221 mm in Example 1 and 0.199 mm in the comparative example. Example 1 was larger, so it can be considered that it is difficult for the Al layer 41 to be exposed on the inner wall surface of the concave portion 13. The measured minimum thickness of the Cu layer 42 in Example 1 was larger than that in the comparative example, and this result was consistent with the result of the CAE analysis.

[0160] As Figure 20 shown in the actual photo, 10 samples (the first sample to the tenth sample) of the battery terminal of Example 1 were manufactured, and the elongation amount of Al and the thickness of the Cu layer 42 were measured for the shaft portion 21 on the left and the shaft portion 21 on the right separated by the concave portion 23, respectively. Here, when a circle tangent to the boundary between the Cu layer 42 and the Al layer 41 is drawn with the position (point) O at the center of the connection between the inner wall surface of the wall portion of the concave portion 13 (in Figure 20 , the range that looks like a straight line in the vertical direction) and the bottom (in Figure 20 , the range that looks like a horizontal line and an inclined line connecting the left and right), the radius of the circle when the radius of the circle is the smallest is defined as the "Cu thickness". In addition, with the bottom of the concave portion 13 (in Figure 20Among them, taking the range that appears as a horizontal line and an inclined line connecting the left and right as a reference (reference line), the length of the perpendicular line drawn from the lowest point of the front end of the Al layer 41 extending downward to the reference line is defined as the "Al elongation amount". The measurement results of the first to fourth samples of Example 1 are shown in Table 4 below. In addition, the measurement results of the fifth to eighth samples of Example 1 are shown in Table 5 below. In addition, the measurement results of the ninth and tenth samples of Example 1 are shown in Table 6 below.

[0161] [Table 4]

[0162]

[0163] As shown in Table 4, in Figure 21 the first sample shown, the Al elongation amount is 0.99 mm on the left side and 1.103 mm on the right side. The average value of the Al elongation amount is 1.047 mm. The Cu thickness is 0.22 mm on the left side and 0.21 mm on the right side. The average value of the Cu thickness is 0.215 mm.

[0164] In addition, in Figure 22 the second sample shown, the Al elongation amount is 1.059 mm on the left side and 1.089 mm on the right side. The average value of the Al elongation amount is 1.074 mm. The Cu thickness is 0.226 mm on the left side and 0.212 mm on the right side. The average value of the Cu thickness is 0.219 mm.

[0165] In addition, in Figure 23 the third sample shown, the Al elongation amount is 1.095 mm on the left side and 1.04 mm on the right side. The average value of the Al elongation amount is 1.068 mm. The Cu thickness is 0.224 mm on the left side and 0.212 mm on the right side. The average value of the Cu thickness is 0.218 mm.

[0166] In addition, in Figure 24 the fourth sample shown, the Al elongation amount is 1.156 mm on the left side and 1.081 mm on the right side. The average value of the Al elongation amount is 1.119 mm. The Cu thickness is N / A (unmeasurable) on the left side and 0.214 mm on the right side. The average value of the Cu thickness is 0.214 mm.

[0167] [Table 5]

[0168]

[0169] As shown in Table 5, in Figure 25In the fifth sample shown, the elongation of Al is 1.038 mm on the left side and 1.052 mm on the right side. The average value of the elongation of Al is 1.045 mm. The thickness of Cu is N / A (unmeasurable) on the left side and 0.231 mm on the right side. The average value of the thickness of Cu is 0.231 mm.

[0170] In addition, in Figure 26 the sixth sample shown, the elongation of Al is 1.022 mm on the left side and 1.069 mm on the right side. The average value of the elongation of Al is 1.046 mm. The thickness of Cu is 0.229 mm on the left side and 0.215 mm on the right side. The average value of the thickness of Cu is 0.222 mm.

[0171] In addition, in Figure 27 the seventh sample shown, the elongation of Al is 1.083 mm on the left side and 1 mm on the right side. The average value of the elongation of Al is 1.042 mm. The thickness of Cu is 0.221 mm on the left side and 0.231 mm on the right side. The average value of the thickness of Cu is 0.226 mm.

[0172] In addition, in Figure 28 the eighth sample shown, the elongation of Al is 0.98 mm on the left side and 1.003 mm on the right side. The average value of the elongation of Al is 1.007 mm. The thickness of Cu is 0.227 mm on the left side and 0.22 mm on the right side. The average value of the thickness of Cu is 0.2235 mm.

[0173] [Table 6]

[0174]

[0175] As shown in Table 6, in Figure 29 the ninth sample shown, the elongation of Al is 1.08 mm on the left side and 0.951 mm on the right side. The average value of the elongation of Al is 1.016 mm. The thickness of Cu is 0.222 mm on the left side and 0.228 mm on the right side. The average value of the thickness of Cu is 0.225 mm.

[0176] In addition, in Figure 30 the tenth sample shown, the elongation of Al is 0.966 mm on the left side and 1.128 mm on the right side. The average value of the elongation of Al is 1.047 mm. The thickness of Cu is 0.224 mm on the left side and 0.217 mm on the right side. The average value of the thickness of Cu is 0.2205 mm.

[0177] The average value of the Al elongation of all the samples (the first sample to the tenth sample) of the above-mentioned Example 1 is 1.066 mm, and the average value of the Cu thickness of all the samples (the first sample to the tenth sample) is 0.220 mm.

[0178] As Figure 31 shown in the physical photograph, seven samples (the first sample to the seventh sample) of the battery terminal of the comparative example were manufactured, and the Al elongation and Cu thickness of each sample were measured on the left and right sides of the recess. Among them, in the same manner as in Example 1, when a circle tangent to the boundary between the Cu layer and the Al layer is drawn with the position (point) O of the inner wall surface of the wall portion connecting the recess 13 (in Figure 31 , the range that looks like a straight line in the vertical direction) and the bottom (in Figure 31 , the range that looks like a horizontal line and an inclined line connecting the left and right) as the center, the radius of the circle when the radius of the circle is the smallest is defined as the "Cu thickness". In addition, with the bottom of the recess 13 (in Figure 31 , the range that looks like a horizontal line and an inclined line connecting the left and right) as the reference (reference line), the length of the perpendicular line drawn from the lowest point of the front end of the Al layer extending downward to the reference line is defined as the "Al elongation". The measurement results of the first to fourth samples of the comparative example are shown in Table 7 below. In addition, the measurement results of the fifth to seventh samples of the comparative example are shown in Table 8 below.

[0179] [Table 7]

[0180]

[0181] As shown in Table 7, in the first sample shown in Figure 32 , the Al elongation is 1.124 mm on the left side and 1.12 mm on the right side. The average value of the Al elongation is 1.122 mm. The Cu thickness is 0.201 mm on the left side and 0.198 mm on the right side. The average value of the Cu thickness is 0.1995 mm.

[0182] In addition, in the second sample shown in Figure 33 , the Al elongation is 1.139 mm on the left side and 1.059 mm on the right side. The average value of the Al elongation is 1.099 mm. The Cu thickness is 0.203 mm on the left side and 0.199 mm on the right side. The average value of the Cu thickness is 0.201 mm.

[0183] In addition, in the Figure 34In the third sample shown, the elongation of Al is 1.12 mm on the left side and 1.096 mm on the right side. The average value of the elongation of Al is 1.108 mm. The thickness of Cu is 0.204 mm on the left side and 0.207 mm on the right side. The average value of the thickness of Cu is 0.2055 mm.

[0184] In addition, in Figure 35 the fourth sample shown, the elongation of Al is 1.138 mm on the left side and 1.061 mm on the right side. The average value of the elongation of Al is 1.100 mm. The thickness of Cu is 0.204 mm on the left side and 0.202 mm on the right side. The average value of the thickness of Cu is 0.203 mm.

[0185] [Table 8]

[0186]

[0187] As shown in Table 8, in Figure 36 the fifth sample shown, the elongation of Al is 1.068 mm on the left side and 1.101 mm on the right side. The average value of the elongation of Al is 1.085 mm. The thickness of Cu is 0.211 mm on the left side and 0.205 mm on the right side. The average value of the thickness of Cu is 0.208 mm.

[0188] In addition, in Figure 37 the sixth sample shown, the elongation of Al is 1.109 mm on the left side and 1.112 mm on the right side. The average value of the elongation of Al is 1.111 mm. The thickness of Cu is 0.209 mm on the left side and 0.208 mm on the right side. The average value of the thickness of Cu is 0.2085 mm.

[0189] In addition, in Figure 38 the seventh sample shown, the elongation of Al is 1.064 mm on the left side and 1.13 mm on the right side. The average value of the elongation of Al is 1.097 mm. The thickness of Cu is 0.209 mm on the left side and 0.209 mm on the right side. The average value of the thickness of Cu is 0.209 mm. In addition, the average value of the elongation of Al for all samples is 1.194 mm, and the average value of the thickness of Cu for all samples is 0.204 mm.

[0190] The average value of the elongation of Al is greater in the comparative example than in Example 1. The larger the value of the elongation of Al, the more the Al layer 41 plastically flows axially (downward). Therefore, it can be known that the Al layer 41 moves more axially in the comparative example than in Example 1. On the other hand, the average value of the Cu thickness is greater in Example 1 than in the comparative example. The larger this value, the more the Cu layer 42 pushes the Al layer 41 outward, or the more the Cu layer 42 resists the inward plastic flow of the Al layer 41. Therefore, it means that the possibility of the Al layer 41 being exposed on the inner wall surface of the recess 13 is lower. Therefore, it can be known that the possibility of the Al layer 41 being exposed in the recess 13 is lower in Example 1 than in the comparative example. That is, it can be known that compared with the comparative example, in Example 1, the Al layer 41 is less likely to move downward and be exposed.

[0191] Figure 39 A graph obtained by plotting the measurement results of the first to tenth samples of Example 1. Figure 39 The shown graph is a graph obtained by plotting the Cu thickness on the vertical axis and the Al elongation on the horizontal axis. The slope of the graph is y = -0.0729x + 0.2975. As shown in this graph, by measuring the cross-section of the actual molded body (terminal component) of the example using A3003, it can be confirmed that the Cu thickness decreases due to the increase in the Al elongation. It can be known that in the case of A3003, it can be said that the smaller the Al elongation, the larger the Cu thickness.

[0192] Figure 40 A graph obtained by plotting the measurement results of the first to seventh samples of the comparative example. Figure 40 The shown graph is a graph obtained by plotting the Cu thickness on the vertical axis and the Al elongation on the horizontal axis. The slope of the graph is y = -0.0145x + 0.2209. As shown in this graph, by measuring the cross-section of the actual molded body (terminal component) of the comparative example using A1050, it can be confirmed that even if the Al elongation increases, the Cu thickness hardly changes. It can be known that in the case of A1050, it cannot be said that the smaller the Al elongation, the larger the Cu thickness.

[0193] According to Figures 20 - 40 Based on the measurement results of the shown actual object and the results of CAE simulation, it can be known that compared with A1050, A3003 can reduce the Al elongation. Therefore, the inventor of the present application learned that compared with A1050, A3003 can suppress the Al elongation to a smaller value, and the smaller the Al elongation, the larger the Cu thickness. Therefore, it can be said that A3003 has a high possibility of sufficiently ensuring the Cu thickness.

[0194] [Modified Example]

[0195] It should be considered that the embodiments and examples (simulations) disclosed herein are illustrative rather than restrictive in all respects. The scope of the present invention is not represented by the descriptions of the above embodiments and examples, but by the claimed technical solutions, and also includes all changes (modifications) within the meaning and scope equivalent to the claimed technical solutions.

[0196] For example, in the present embodiment, an example of a battery terminal using a composite material in which the Cu layer is made of Cu (pure copper) is described, but the present invention is not limited thereto. In the present invention, for example, it may also be a battery terminal using a composite material in which the Cu layer is made of a Cu alloy.

[0197] Description of Reference Numerals

[0198] 1 Lithium ion battery (battery), 2 Cover member (housing), 3 Can member (housing), 4a Positive electrode (positive electrode side member), 4b Negative electrode (negative electrode side member), 4c Separator, 5 Negative electrode current collector (negative electrode side member), 6 Positive electrode current collector (positive electrode side member), 10 Negative electrode terminal (battery terminal), 11 Shaft portion, 12 Flange portion, 13 Recessed portion, 40 Composite material, 41 Al layer, 42 Cu layer, 51 Blank for stamping.

Claims

1. A terminal (10) for a battery, characterized in that, Comprising: A flange portion (12) formed by diffusion bonding an Al layer (41) made of an Al alloy and a Cu layer (42) made of Cu in a stacking direction, wherein the Al alloy contains Al with the highest content and Mn or Mg with the second highest content and has a conductivity of 30% IACS or more; a shaft portion (11) extending from the flange portion in the stacking direction of the Al layer and the Cu layer; and a recess portion (13) located at an end portion of the shaft portion on the Cu layer side and having a surface formed by the Cu layer.

2. The battery terminal according to claim 1, wherein: The Al alloy has a conductivity of 40% IACS or more.

3. The battery terminal according to claim 1 or 2, wherein: The Al alloy contains Al with the highest content and Mn with the second highest content.

4. A method for manufacturing a terminal (10) for a battery, characterized in that, Comprising: A step of preparing a composite material (40) by diffusion bonding an Al layer (41) made of an Al alloy and a Cu layer (42) made of Cu in a stacking direction, wherein the Al alloy contains Al with the highest content and Mn or Mg with the second highest content and has a conductivity of 30% IACS or more; A step of tempering the composite material into a blank for stamping (51), wherein the blank for stamping is a material for stamping formed by diffusion bonding the Al layer having a Vickers hardness of 30 HV or more and the Cu layer having a Vickers hardness of 50 HV or more and 80 HV or less in a stacking direction; A step of performing stamping on the blank for stamping so as to form a flange portion (12), a shaft portion (11), and a recess portion (13), wherein the shaft portion (11) extends from the flange portion in the stacking direction of the Al layer and the Cu layer, and the recess portion (13) is located at an end portion of the shaft portion on the Cu layer side and has a surface formed by the Cu layer.

5. The method for manufacturing a battery terminal according to claim 4, wherein: In the step of tempering into a blank for stamping, the Vickers hardness of the Al layer is tempered to 30 HV or more and 75 HV or less, and the Vickers hardness of the Cu layer is tempered to 50 HV or more and 80 HV or less.

6. The method for manufacturing a battery terminal according to claim 4 or 5, wherein: In the step of preparing the composite material, the Al layer made of the Al alloy having a conductivity of 40% IACS or more and the Cu layer made of Cu are diffusion bonded in a stacking direction to prepare the composite material.

7. A battery (1), wherein: It includes a battery terminal (10), an electrolyte, a housing (2) for storing the electrolyte, a positive electrode side component (4a, 6) for forming the positive electrode side of the battery, a negative electrode side component (4b, 5) for forming the negative electrode side of the battery, and a separator (4c) for separating the positive electrode and the negative electrode of the battery. Among them, the battery terminal (10) includes: a flange portion (12) formed by diffusion bonding an Al layer (41) made of an Al alloy and a Cu layer (42) made of Cu in the stacking direction. The Al alloy contains the most Al and the second most Mn or Mg and has a conductivity of 30% IACS or more; a shaft portion (11) extending from the flange portion in the stacking direction of the Al layer and the Cu layer; and a recess (13) located at the end of the shaft portion on the Cu layer side and having a surface formed by the Cu layer. The recess of the battery terminal is fixed to the negative electrode side component by riveting.

8. A method for manufacturing a battery, characterized in that: The battery (1) includes a battery terminal (10), an electrolyte, a housing (3) for storing the electrolyte, a positive electrode side component (4a, 6) for forming the positive electrode side of the battery, a negative electrode side component (4b, 5) for forming the negative electrode side of the battery, and a separator (4c) for separating the positive electrode and the negative electrode of the battery. Among them, the battery terminal (10) includes: a flange portion (12) formed by diffusion bonding an Al layer (41) made of an Al alloy and a Cu layer (42) made of Cu in the stacking direction. The Al alloy contains the most Al and the second most Mn or Mg and has a conductivity of 30% IACS or more; a shaft portion (11) extending from the flange portion in the stacking direction of the Al layer and the Cu layer; and a recess (13) located at the end of the shaft portion on the Cu layer side and having a surface formed by the Cu layer. The method for manufacturing the battery includes a step of fixing the recess of the battery terminal to the negative electrode side component by riveting.

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