Battery terminal and secondary battery

Abstract

To provide a battery terminal enabling materialization of improvement of a long-period electric reliability of a secondary battery.SOLUTION: A battery terminal NS is provided, including: a metallic first member 26; and a metallic second member 31. The first member 26 is composed of: a first plate-like portion 27 in which at least a part of a front surface is a bus bar joint portion 27c; shaft portions 28a and 29a; and umbrella portions 28b and 29b; and two caulked portions 28 and 29 formed on a back surface of the first plate-like portion 27. The second member 31 includes: a second plate-like portion 32 in which two holes 33 and 34 penetrating through a front and a back are formed; and a current collection portion 35 provided spanning the back surface of the second plate-like portion 32. In at least a bus bar joint portion 27c and the current collection portion 35, the caulked portion 28 of which the center is near in a direction views orthogonal to the front surface of the first plate-like portion 27 is a contact caulked portion to any one of a bus bar joint portion 27c and the current collection portion 35. In the contact caulked portion, the umbrella portion 28a is not bonded to the back surface of the second plate-like portion 32 in an ultrasonic manner.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a battery terminal and a secondary battery. [Background technology]

[0002] Secondary batteries used as power sources for electric vehicles, hybrid vehicles, and other electrically powered vehicles are electrically connected together to form a battery module having increased charge / discharge capacity and output power. The secondary batteries are electrically connected together, for example, via bus bars that join the positive and negative terminals of adjacent secondary batteries.

[0003] Here, when adopting a structure in which a bus bar is joined to each terminal by welding, taking into consideration the weldability of the bus bar, it is preferable that the portions where the bus bars of each terminal are connected (bus bar joints) be made of the same type of metallic material.

[0004] In view of this, there have been proposed secondary batteries in which the bus bar joints of the terminals are made of the same type of metal material, as described in Patent Document 1, for example.

[0005] In the secondary battery described in Patent Document 1, the battery terminals are composed of a current collecting member connected to a power generating body, an external terminal exposed to the outside of the case and to which a bus bar is welded and joined to a bus bar joint portion, and a connection member that connects the current collecting member and the external terminal. In this secondary battery, the upper end of the connection member is crimped and fixed to the crimp portion of the external terminal, and the lower end of the connection portion is crimped and fixed to the current collecting member. In this secondary battery, when the current collecting member, connection member, and external terminal on the positive electrode side are made of aluminum, the current collecting member and connection member on the negative electrode side are made of copper, and the bus bar is made of aluminum, for example, the negative electrode external terminal is made of a partially clad material mainly made of an aluminum base material with a copper flat plate joined to the surface of the crimp portion.

[0006] In this secondary battery, the connection member and the external terminal are integrated by crimping at the crimping portion of the external terminal on the negative electrode side, and then the connection member, both made of copper, and the copper plate are joined by welding. Therefore, in this secondary battery, electrical continuity is ensured between the members that make up the battery terminals, and both the busbar joints of the positive and negative external terminals are made of an aluminum base material. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2012-123946 A Summary of the Invention [Problem to be solved by the invention]

[0008] Incidentally, in the secondary battery described in Patent Document 1, the upper end of the connection terminal is crimped to form an umbrella shape that spreads out over the surface of the crimped portion of the external terminal, and this portion is welded and joined to the surface of the crimped portion, thereby ensuring conductivity between the connection terminal and the external terminal.

[0009] However, when an external force is applied to the battery terminal through the busbar joint or the connection with the power generator during manufacture or use, the external force may deform the shape of the upper end of the connection terminal, reducing the contact area between the connection member and the crimped surface of the external terminal. When the contact area between the two is reduced, the electrical resistance increases, and the battery is unable to exhibit satisfactory electrical conductivity. In other words, the secondary battery described in Patent Document 1 has a problem in that it is difficult to maintain electrical reliability over a long period of time.

[0010] The present invention has been made in consideration of the above circumstances, and has an object to provide a battery terminal and a secondary battery that can achieve improved long-term electrical reliability. [Means for solving the problem]

[0011] The characteristic configuration of the battery terminal according to the present invention for achieving the above object is as follows: A battery terminal having a first member and a second member made of metal, The first member is A first plate-shaped portion, at least a part of a surface of which is a bus bar joint portion; The first plate-shaped portion has a shaft portion and a head portion, and two crimping portions are formed on the rear surface of the first plate-shaped portion. The second member is A second plate-shaped portion having two holes formed therein penetrating from the front to the back; A current collecting portion provided in connection with the rear surface of the second plate-shaped portion, Each of the crimping portions is formed such that the shaft portion is located inside each of the holes and the umbrella portion extends over a rear surface of the second plate-shaped portion, a proximate crimping portion is a crimping portion that is close to a center of at least one of the bus bar joint portion and the current collecting portion when viewed in a direction perpendicular to the surface of the first plate-shaped portion, and an umbrella portion of the proximate crimping portion is not ultrasonically joined to the back surface of the second plate-shaped portion, The other crimped portion other than the adjacent crimped portion has an umbrella portion ultrasonically bonded to the rear surface of the second plate-shaped portion.

[0012] According to the above characteristic configuration, the umbrella portion of the first member and the rear surface of the second plate-shaped portion of the second member are not ultrasonically joined at the crimping portion (proximal crimping portion) close to the busbar joint and current collecting portion where external force acts. This allows the proximal crimping portion to absorb external force, making it difficult for external force to be applied to the other crimping portion. As a result, the load on the ultrasonically joined portion (the interface between the umbrella portion of the first member and the rear surface of the second plate-shaped portion of the second member) in the other crimping portion is reduced, and electrical continuity between the first member and the second member can be ensured for a long period of time. In other words, a battery terminal having the above characteristic configuration can achieve improved long-term electrical reliability. According to the above characteristic configuration, the first member and the second member are fixed by the two crimping portions and the holes, so that the two members can be prevented from rotating relative to each other. Furthermore, when both of the two crimped portions are ultrasonically joined, one crimped portion is ultrasonically joined and then the other crimped portion is ultrasonically joined, but when the other crimped portion is ultrasonically joined, the initially joined portion may be damaged by ultrasonic joining. However, according to the above-mentioned characteristic configuration, the umbrella portion of the first member and the rear surface of the second plate-shaped portion of the second member are ultrasonically joined at only one of the two crimped portions. Therefore, problems during manufacturing are less likely to occur compared to when both of the two crimped portions are ultrasonically joined.

[0013] Further characteristic features of the battery terminal according to the present invention are as follows: The proximal crimped portion is a crimped portion whose center overlaps with the bus bar joint portion and whose center is close to the current collecting portion when viewed in a direction perpendicular to the surface of the first plate-shaped portion.

[0014] According to the above characteristic configuration, the first member and the second member are not ultrasonically joined at the crimping portion close to both the busbar joint and the current collecting portion, where an external force acts. As a result, with a battery terminal having the above characteristic configuration, the external force can be absorbed better by the proximate crimping portion, and the external force is less likely to be applied to other crimping portions, and as a result, electrical continuity between the first member and the second member can be maintained for a longer period of time.

[0015] Further characteristic features of the battery terminal according to the present invention are as follows: The proximal crimped portion is a crimped portion whose center is closer to which of the bus bar joint portion and the current collecting portion is subjected to a greater external force when viewed in a direction perpendicular to the surface of the first plate-shaped portion.

[0016] According to the above characteristic configuration, the first member and the second member are not ultrasonically joined at the crimping portion close to the busbar joint or the current collecting portion, whichever receives the larger external force. As a result, with a battery terminal having the above characteristic configuration, the larger external force acting on the battery terminal can be preferentially absorbed by the adjacent crimping portion, and the other crimping portions are less likely to be subjected to a large external force. Therefore, it is easy to maintain electrical continuity between the first member and the second member for a long period of time.

[0017] Further characteristic features of the battery terminal according to the present invention are as follows: an external force acting on the bus bar joint portion is greater than that acting on the current collecting portion; The adjacent crimped portion is a crimped portion whose center overlaps with the bus bar joint portion when viewed in a direction perpendicular to the surface of the first plate-shaped portion.

[0018] According to the above-described characteristic configuration, the first member and the second member are not ultrasonically joined at the crimping portion closer to the busbar joint, where a larger external force acts than on the current collecting portion, so that the large external force acting on the busbar joint can be preferentially absorbed by the crimping portion.

[0019] Further characteristic features of the battery terminal according to the present invention are as follows: The current collecting portion is subjected to a larger external force than the bus bar joint portion, The proximal crimped portion is a crimped portion whose center is close to the current collecting portion when viewed in a direction perpendicular to the surface of the first plate-shaped portion.

[0020] According to the above-described characteristic configuration, the first member and the second member are not ultrasonically joined at the crimping portion closer to the current collecting portion, which is subjected to a greater external force than the busbar joint, so that the large external force acting on the current collecting portion can be preferentially absorbed by the crimping portion.

[0021] Further characteristic features of the battery terminal according to the present invention are as follows: the first member is made of aluminum or an aluminum alloy; The second member is made of copper or a copper alloy.

[0022] According to the above characteristic configuration, a suitable negative electrode terminal can be realized in which the metal constituting the current collecting portion joined to the negative electrode of the electrode body is made of copper or a copper alloy, and the bus bar joint portion is made of aluminum or an aluminum alloy.

[0023] In order to achieve the above object, the secondary battery according to the present invention has the following characteristic configuration: A housing having an opening; a cover for sealing an opening of the housing; An electrode body disposed within the housing; a battery terminal electrically connected to the electrode body, the battery terminal has a first member and a second member made of metal; The first member is A first plate-shaped portion, at least a part of a surface of which is a bus bar joint portion; The first plate-shaped portion has a shaft portion and a head portion, and two crimping portions are formed on the rear surface of the first plate-shaped portion. The second member is A second plate-shaped portion having two holes formed therein penetrating from the front to the back; A current collecting portion provided in connection with the rear surface of the second plate-shaped portion, Each of the crimping portions is formed such that the shaft portion is located inside each of the holes and the umbrella portion extends over a rear surface of the second plate-shaped portion, a proximate crimping portion is a crimping portion that is close to a center of at least one of the bus bar joint portion and the current collecting portion when viewed in a direction perpendicular to the surface of the first plate-shaped portion, and an umbrella portion of the proximate crimping portion is not ultrasonically joined to the back surface of the second plate-shaped portion, The other crimping portions other than the adjacent crimping portion have their umbrella portions ultrasonically bonded to the back surface of the second plate-shaped portion, The surface of the first plate-shaped portion is located outside the lid, and the current collecting portion is electrically connected to the electrode body inside the casing.

[0024] According to the above characteristic configuration, the umbrella portion of the first member and the rear surface of the second plate-shaped portion of the second member are not ultrasonically joined at the proximal crimping portion, which is a crimping portion close to the busbar joint and current collecting portion where an external force acts. This allows the proximal crimping portion to absorb external forces, and makes it difficult for external forces to be applied to the other crimping portion. As a result, the load on the ultrasonically joined portion of the other crimping portion (the interface between the umbrella portion of the first member and the rear surface of the second plate-shaped portion of the second member) is reduced, and electrical continuity between the first member and the second member can be ensured for a long period of time. In other words, a secondary battery having the above characteristic configuration can achieve improved long-term electrical reliability. According to the above characteristic configuration, the first member and the second member are fixed by the two crimping portions and the holes, so that the two members can be prevented from rotating relative to each other. Furthermore, according to the above characteristic configuration, the umbrella portion of the first member and the rear surface of the second plate-shaped portion of the second member are ultrasonically joined at only one of the two crimping portions, which makes it less likely that problems such as damage to the joint will occur during manufacturing compared to when both of the two crimping portions are ultrasonically joined.

[0025] Further characteristic configurations of the secondary battery according to the present invention are as follows: The bus bar is connected to the bus bar joint.

[0026] According to the above characteristic configuration, it is possible to construct a battery module in which a plurality of secondary batteries are connected by bus bars. Effect of the Invention

[0027] As described above, the battery terminal and the secondary battery according to the present invention can achieve improved long-term electrical reliability. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is an exploded perspective view of a secondary battery according to an embodiment. [Diagram 2] 1 is a cross-sectional view showing a schematic configuration of a secondary battery according to an embodiment. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2. [Figure 4] FIG. 2 is a perspective view showing a negative electrode terminal. [Diagram 5] FIG. 5 is a cross-sectional view of part VV of FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. 4 is a perspective view showing a state in which a secondary battery is connected by a bus bar. [Figure 9] FIG. 11 is a bottom view showing a negative electrode terminal according to another embodiment. [Figure 10] FIG. 11 is a bottom view showing a negative electrode terminal according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, a battery terminal according to an embodiment of the present invention and a secondary battery including the battery terminal will be described with reference to the drawings. Note that, in the following, an embodiment in which the battery terminal is used in a lithium ion secondary battery will be described as an example. In addition, in the following, each description and each drawing will be appropriately simplified in order to clarify the description.

[0030] [Overview of secondary battery 1] Fig. 1 is an exploded perspective view of a secondary battery according to this embodiment. Fig. 2 is a cross-sectional view showing a schematic configuration of a secondary battery 1 according to this embodiment. In the following description, the direction parallel to the height direction of the secondary battery 1 is defined as the Z-axis direction, the direction parallel to the longitudinal direction of the electrode body 20 is defined as the X-axis direction, and the direction parallel to the thickness direction of the electrode body 20 is defined as the Y-axis direction. The Z-axis direction is parallel to the up-down direction, and the X-axis and Y-axis directions are perpendicular to each other and parallel to the horizontal direction.

[0031] 1 and 2, the secondary battery 1 of this embodiment includes a battery case 10 consisting of a case body 11 and a sealing plate 12, battery terminals PS and NS consisting of metallic external terminals 25, 26 and current collecting terminals 30, 31, and an electrode body 20. The secondary battery 1 of this embodiment is a sealed secondary battery in which the electrode body 20, the current collecting terminals 30, 31, etc. are accommodated inside the case body 11, the opening of the case body 11 is sealed with the sealing plate 12, and an electrolyte is injected into the inside of the case body 11.

[0032] [Configuration of battery case 10] As shown in Fig. 1 and Fig. 2, a battery case 10 of this embodiment is composed of a case body 11 having a generally rectangular parallelepiped shape with an open top, and a sealing plate 12 that seals the opening of the case body 11. In this embodiment, both the case body 11 and the sealing plate 12 are made of aluminum, but are not limited to this. Various metals and alloys can be used as materials for the case body 11 and the sealing plate 12. In this embodiment, the case body 11 corresponds to the "housing" and the sealing plate 12 corresponds to the "lid".

[0033] The sealing plate 12 has a shape corresponding to the shape of the opening of the case body 11. The sealing plate 12 of this embodiment is made of a flat plate member having a generally rectangular shape when viewed in the Z-axis direction. The sealing plate 12 has mounting holes 12a formed at both longitudinal ends (both longitudinal ends) that penetrate the top and bottom surfaces and into which a positive electrode insulating member 36 and a negative electrode insulating member 37, which will be described later, are fitted. As will be described in detail later, the sealing plate 12 has a positive electrode terminal PS disposed at one longitudinal end side (one longitudinal end side) and a negative electrode terminal NS disposed at the other longitudinal end side (the other longitudinal end side).

[0034] [Configuration of electrode body 20] In this embodiment, the electrode body 20 is composed of a wound body in which long strip-shaped positive and negative electrode materials are laminated with a strip-shaped separator interposed therebetween, wound, and compressed into a flat shape. As shown in Figs. 1 and 2, the electrode body 20 of this embodiment is substantially rectangular when viewed in the thickness direction (Y-axis direction), and a positive electrode terminal joint 21 in which the positive electrode material is collected is formed at one end side in the longitudinal direction (X-axis direction) when viewed in the thickness direction, and a negative electrode terminal joint 22 in which the negative electrode material is collected is formed at the other end side. The structure of the electrode body 20 is not particularly limited, and various structures used in general sealed secondary batteries can be adopted. In addition, the materials used for the positive and negative electrode materials are not particularly limited, but in this embodiment, aluminum is used for the positive electrode material and copper is used for the negative electrode material.

[0035] In this embodiment, the electrode body 20 is covered with an insulating film and housed inside the case body 11 in a position in which the thickness direction and the longitudinal direction are parallel to the horizontal direction. The electrode body 20 and the case body 11 are insulated from each other by an insulating film (not shown).

[0036] [Positive and negative electrode configurations] In this embodiment, the secondary battery 1 includes a positive external terminal 25 and a negative external terminal 26 as external terminals, and a positive current collector terminal 30 and a negative current collector terminal 31 as current collector terminals. The secondary battery 1 of this embodiment also includes a positive insulating member 36 and a negative insulating member 37. In this embodiment, the positive external terminal 25 and the positive current collector terminal 30 form a positive terminal PS, and the negative external terminal 26 and the negative current collector terminal 31 form a negative terminal NS. In this embodiment, the negative terminal NS corresponds to a "battery terminal."

[0037] In this embodiment, the positive electrode side and the negative electrode side have almost the same configuration, but the materials of the external terminals and the current collector terminals are different. Specifically, in this embodiment, the same metal material is used for the positive electrode external terminal 25 and the positive electrode current collector terminal 30 constituting the positive electrode terminal PS. On the other hand, different metal materials are used for the negative electrode external terminal 26 and the negative electrode current collector terminal 31 constituting the negative electrode terminal NS.

[0038] The configuration of the negative electrode side will be described below with reference to Fig. 3 to Fig. 6. Fig. 3 is a cross-sectional view of the III-III portion of Fig. 2. Fig. 4 is a perspective view showing the negative electrode terminal NS, Fig. 5 is a cross-sectional view of the VV portion of Fig. 4, and Fig. 6 is a bottom view of the negative electrode terminal NS.

[0039] The negative electrode external terminal 26 is a terminal for external connection. The negative electrode external terminal 26 has a plate-shaped portion 27 that is generally rectangular when viewed in the Z-axis direction, and a first crimping portion 28 and a second crimping portion 29 that extend downward from a back surface 27b of the plate-shaped portion 27. In this embodiment, the first crimping portion 28 and the second crimping portion 29 are arranged side by side along the X-axis direction, with the first crimping portion 28 being arranged on the other side in the X-axis direction and the second crimping portion 29 being arranged on one side in the X-axis direction. More specifically, the plate-shaped portion 27 is divided into two equal parts in the X-axis direction, and the first crimping portion 28 is formed on the other side in the X-axis direction when viewed in the Z-axis direction, and the second crimping portion 29 is provided on one side in the X-axis direction. In addition, the negative electrode external terminal of this embodiment is made of aluminum. In this embodiment, the negative electrode external terminal 26 corresponds to the "first member", and the plate-shaped portion 27 of the negative electrode external terminal 26 corresponds to the "first plate-shaped portion".

[0040] A bus bar joint 27c to which an aluminum bus bar is welded is provided on surface 27a of plate-shaped portion 27. In the present embodiment, bus bar joint 27c is set at a position overlapping with center O1 of first crimping portion 28 when viewed in a direction perpendicular to surface 27a of plate-shaped portion 27 (when viewed in the Z-axis direction). More specifically, the surface of plate-shaped portion 27 is divided into two equal parts in the X-axis direction, and a region on the other side in the X-axis direction is set as bus bar joint 27c.

[0041] In this embodiment, each of the crimped portions 28, 29 has a cylindrical shaft portion 28a, 29a extending downward from the back surface 27b of the plate-shaped portion 27, and an umbrella portion 28b, 29b formed at the lower end of each of the shaft portions 28a, 29a. Although details will be described later, the negative external terminal 26 and the negative current collector terminal 31 are fixed together by an engagement relationship between these two crimped portions 28, 29 and holes 33, 34 of the negative current collector terminal 31.

[0042] The negative current collector terminal 31 is a terminal for inputting and outputting electric power from the electrode body 20. The negative current collector terminal 31 is disposed on the lower surface side of the sealing plate 12, in other words, inside the case body 11. In this embodiment, the negative current collector terminal 31 is made of copper. In this embodiment, the negative current collector terminal 31 corresponds to the "second member."

[0043] In this embodiment, the negative electrode current collector terminal 31 has a plate-shaped portion 32 that is generally rectangular when viewed in the Z-axis direction, and a plate-shaped current collector portion 35 that extends downward from a back surface 32b of the plate-shaped portion 32. In this embodiment, the plate-shaped portion 32 of the negative electrode current collector terminal 31 corresponds to the "second plate-shaped portion."

[0044] The plate-shaped portion 32 is formed with a first through hole 33 and a second through hole 34 penetrating from the front to the back. In this embodiment, the first through hole 33 and the second through hole 34 are formed side by side along the X-axis direction, with the first through hole 33 formed on the other side in the X-axis direction and the second through hole 34 formed on one side in the X-axis direction. In this embodiment, recesses 33a, 34a are formed on the back surface 32b of the plate-shaped portion 32, which have a larger diameter than the through holes 33, 34 as viewed in the Z-axis direction and open to the back surface 32b side so as to communicate with the through holes 33, 34. In this embodiment, the shaft portion 28a of the first crimping portion 28 is inserted into the first through hole 33, and the shaft portion 29a of the second crimping portion 29 is inserted into the second through hole 34, and the umbrella portions 28b, 29b of the crimping portions 28, 29 extend into the recesses 33a, 34a, and the umbrella portions 28b, 29b are formed to have a larger diameter than the shaft portions 28a, 29a when viewed in the Z-axis direction. In other words, the crimping portions 28, 29 are formed so that the shaft portions 28a, 29a are located inside the through holes 33, 34, and the umbrella portions 28b, 29b extend over the back surface 32b of the plate-shaped portion 32.

[0045] In this embodiment, the current collecting part 35 is composed of a base part 35a extending downward from an edge along the longitudinal direction of the back surface 32b of the plate-shaped part 32, and a main part 35b extending downward from the other side of the X-axis direction of the base part 35a and formed at a position protruding from the plate-shaped part 32 to the other side of the X-axis direction as viewed in the Z-axis direction, and is a member having a substantially L-shape as viewed in the Y-axis direction. That is, the current collecting part 35 is provided connected to the back surface 32b of the plate-shaped part 32 of the negative electrode current collecting terminal 31. In addition, the lower end of the main part 35b has an electrode connection part 35c to which the negative electrode terminal joint part 22 of the electrode body 20 is joined.

[0046] The negative terminal NS, which is composed of the negative external terminal 26 and the negative current collector terminal 31, is composed of two members made of different metal materials. The negative terminal NS is configured such that the negative external terminal 26 and the negative current collector terminal 31 are fixed together by the engagement of the crimped portions 28, 29 with the through holes 33, 34.

[0047] Specifically, in the negative terminal NS, the shaft portions 28a, 29a of the two crimping portions 28, 29 in the negative external terminal 26 are inserted into the two through holes 33, 34 in the negative current collector terminal 31 to bring the back surface 27b of the plate-shaped portion 27 into contact with the front surface 32a of the plate-shaped portion 32, and the tips of the shaft portions 28a, 29a are deformed by press working to form the umbrella portions 28b, 29b. This fixes the negative external terminal 26 and the negative current collector terminal 31.

[0048] In this manner, the negative external terminal 26 and the negative current collector terminal 31 are fixed together by the two crimping portions 28, 29 and the through holes 33, 34, thereby preventing the two members from rotating relative to each other.

[0049] Here, external forces due to vibrations and the like act on each part of the terminal of the secondary battery 1 during manufacture and use. For example, external forces are likely to act on the busbar joint 27c of the negative electrode terminal NS due to vibrations and the like when the busbar B is welded and joined, or when the battery module is mounted on a vehicle and used. In addition, external forces are likely to act on the current collector 35 due to shaking of the electrode body when joined to the electrode body 20 or when used after being mounted on the vehicle. When an external force acts on the busbar joint 27c or the current collector 35, a load is likely to be applied to the two crimped parts 28, 29 that are closer to the busbar joint 27c and the current collector 35. Therefore, if only the crimped parts 28, 29 closer to the busbar joint 27c and the current collector 35 are joined, the shapes of the umbrella parts 28b, 29b are deformed by the load, and the contact area is reduced, which may result in a decrease in the electrical conductivity of the negative electrode terminal NS.

[0050] Furthermore, when both of the two crimped portions 28, 29 are ultrasonically joined to the plate-like portion 32 in order to ensure the electrical continuity of the negative electrode terminal NS, one of the crimped portions is ultrasonically joined and then the other crimped portion is ultrasonically joined. Therefore, when the other crimped portion is ultrasonically joined, the joint between the previously ultrasonically joined crimped portion and the plate-like portion may be damaged, and as a result, the electrical continuity of the negative electrode terminal NS may not be ensured.

[0051] Therefore, in this embodiment, of the two crimping portions 28, 29, the center O1 overlaps with the busbar joint 27c when viewed in the Z-axis direction, and the interface between the umbrella portion 28b of the first crimping portion 28 closer to the current collecting portion 35 and the back surface 32b of the plate-shaped portion 32 is not ultrasonically bonded, while the interface between the umbrella portion 29b of the second crimping portion 29 and the back surface 32b of the plate-shaped portion 32 is ultrasonically bonded. In other words, in this embodiment, the first crimping portion 28, which has a center O1 close to both the busbar joint 27c and the current collecting portion 35 when viewed in a direction perpendicular to the surface 27a of the plate-shaped portion 27 (when viewed in the Z-axis direction), is considered to be a proximate crimping portion, and the first crimping portion 28 serving as the proximate crimping portion has its umbrella portion 28b not ultrasonically joined to the back surface 32b of the plate-shaped portion 32 in the negative electrode current collecting terminal 31, and the second crimping portion 29 has its umbrella portion 29b ultrasonically joined to the back surface 32b of the plate-shaped portion 32.

[0052] 7, when the distances from the centers O1, O2 of the crimped portions 28, 29 to the center O3 of the current collecting portion 35 as viewed in the Z-axis direction are R1, R2, respectively, the distance R1 of the first crimped portion 28 is shorter than the distance R2 of the second crimped portion 29, and the center O1 of the first crimped portion 28 overlaps with the bus bar joint portion 27c as viewed in the Z-axis direction. Therefore, in this embodiment, the first crimped portion 28 is the proximal crimped portion. Note that in this embodiment, the center O3 of the current collecting portion 35 is synonymous with the position of the center of gravity of the current collecting portion 35 as viewed in the Z-axis direction.

[0053] Then, the umbrella portion 29b of the second crimping portion 29 and the back surface 32b of the plate-like portion 32 are ultrasonically joined together, thereby ensuring electrical continuity between the negative external terminal 26 and the negative current collecting terminal 31.

[0054] On the other hand, in the first crimping portion 28, which is a proximal crimping portion, the interface between the umbrella portion 28b and the back surface 32b of the plate-shaped portion 32 is not ultrasonically joined. Therefore, an external force acting on the busbar joint 27c and the current collecting portion 35 is absorbed by the first crimping portion 28, and the external force is unlikely to act on the second crimping portion 29 ultrasonically joined to the back surface 32b of the plate-shaped portion 32. This reduces the load on the ultrasonically joined portion of the second crimping portion 29 (the interface between the umbrella portion 29b and the back surface 32b of the plate-shaped portion 32), and ensures conduction between the negative electrode external terminal 26 and the negative electrode current collecting terminal 31 for a long period of time. In other words, the secondary battery of this embodiment achieves improved long-term electrical reliability.

[0055] Furthermore, since the second crimping portion 29 and the plate-shaped portion 32 of the two crimping portions 28, 29 are ultrasonically bonded, damage to the joint during manufacturing is less likely to occur compared to when both of the two crimping portions 28, 29 are ultrasonically bonded, and conductivity of the negative terminal NS can be ensured.

[0056] The negative electrode insulating member 37 is a member made of an insulating material. The negative electrode insulating member 37 of the present embodiment is a member for integrating the negative electrode terminal NS and the sealing plate 12 together and for insulating the negative electrode terminal NS from the sealing plate 12.

[0057] In this embodiment, with the negative terminal NS inserted into the mounting hole 12a of the sealing plate 12, the negative electrode insulating member 37 is insert-molded to integrate the negative electrode terminal NS with the sealing plate 12 via the negative electrode insulating member 37. The negative electrode terminal NS and the sealing plate 12 are insulated by the negative electrode insulating member 37, and the negative electrode insulating member 37 maintains airtightness between the negative electrode terminal NS and the mounting hole 12a of the sealing plate 12. The electrode connection portion 35c of the negative electrode current collector terminal 31 is joined to the negative electrode terminal joint portion 22 of the electrode body 20.

[0058] Regarding the positive electrode side of this embodiment, the positive electrode terminal PS is different from the negative electrode terminal NS, which is a dissimilar material joining member, and is formed by appropriately joining a positive electrode external terminal 25 and a positive electrode current collecting terminal 30, which are made of the same metal material (aluminum in this embodiment).

[0059] Although details are omitted, on the positive electrode side of this embodiment, with the positive electrode terminal PS inserted into the mounting hole of the sealing plate 12, a positive electrode insulating member 36 is insert-molded to integrate the positive electrode terminal PS with the sealing plate 12 via the positive electrode insulating member 36. As with the negative electrode side, on the positive electrode side, the positive electrode terminal PS and the sealing plate 12 are insulated from each other by the positive electrode insulating member 36, and the positive electrode insulating member 36 maintains airtightness between the positive electrode terminal PS and the mounting hole of the sealing plate 12. In addition, the electrode connection portion 30a of the positive electrode collector terminal 30 is joined to the positive electrode terminal joint portion 21 of the electrode body 20.

[0060] In this embodiment, on the positive electrode side, of the two fastening portions, the center overlaps with the busbar joint when viewed in the Z-axis direction, and the interface between the umbrella portion of the fastening portion closer to the current collecting portion and the rear surface of the plate-shaped portion is not ultrasonically joined, while the interface between the umbrella portion of the other fastening portion and the rear surface of the plate-shaped portion is ultrasonically joined.

[0061] When the secondary battery 1 having the above configuration is used as a power source for an electric vehicle, it is used in the form of a battery module with increased charge / discharge capacity and output power. In this case, as shown in Fig. 8, the positive terminal PS of one secondary battery 1 and the negative terminal NS of an adjacent secondary battery 1 are electrically connected by welding a bus bar B to each bus bar joint 27c.

[0062] [Another embodiment] [1] In the above embodiment, a configuration has been described in which, of the two crimping portions 28, 29, the center O1 overlaps with the bus bar joint 27c when viewed in the Z-axis direction, the interface between the umbrella portion 28b of the first crimping portion 28 closer to the current collecting portion 35 and the back surface 32b of the plate-shaped portion 32 is not joined, and the interface between the umbrella portion 29b of the second crimping portion 29 and the back surface 32b of the plate-shaped portion 32 is ultrasonically joined, but the present invention is not limited to such a configuration. The crimping portion ultrasonically joined to the plate-shaped portion 32 may be changed as appropriate in consideration of the position of the bus bar joint 27c and the magnitude of the external force acting on the bus bar joint 27c and the current collecting portion 35. 9 and 10 are bottom views showing a negative electrode terminal NS according to another embodiment. As shown in Fig. 9 and 10, when the surface of plate-shaped portion 27 is divided into two equal parts in the X-axis direction and the region on one side in the X-axis direction is set as bus bar joint 27c, first crimping portion 28 is closer to current collecting portion 35 (in other words, distances R1, R2 to center O3 are shorter), and second crimping portion 29 overlaps with bus bar joint 27c as viewed in the Z-axis direction (in other words, the center of second crimping portion 29 is closer to bus bar joint 27c). Here, when the external force acting on busbar joint 27c is greater than that on current collecting portion 35, it is preferable that a crimping portion whose center overlaps with busbar joint 27c when viewed in a direction perpendicular to front surface 32a of plate-shaped portion 32 (when viewed in the Z-axis direction) is the proximal crimping portion, and that an interface between an umbrella portion of the proximal crimping portion and the back surface of the plate-shaped portion is not ultrasonically joined. Specifically, as shown in Fig. 9, it is preferable that a second crimping portion 29 which overlaps with busbar joint 27c when viewed in the Z-axis direction, which is greater than that on current collecting portion 35, is the proximal crimping portion, and that an interface between umbrella portion 29b of second crimping portion 29 and back surface 32b of plate-shaped portion 32 is not ultrasonically joined, but an interface between umbrella portion 28b of first crimping portion 28 and back surface 32b of plate-shaped portion 32 is ultrasonically joined. In this way, by adopting a configuration in which the second crimping portion 29 overlapping with the bus bar joint 27c is made a proximal crimping portion and the second crimping portion 29 and the plate-shaped portion 32 are not ultrasonically joined, the large external force acting on the bus bar joint 27c can be preferentially absorbed by the second crimping portion 29, and damage to the joint between the first crimping portion 28 and the plate-shaped portion 32 can be suppressed. On the other hand, when the current collecting portion 35 is subjected to a larger external force than the busbar joint 27c, it is preferable that the crimping portion whose center is closer to the current collecting portion 35 when viewed in a direction perpendicular to the front surface 32a of the plate-shaped portion 32 (when viewed in the Z-axis direction) is the proximal crimping portion, and that the interface between the umbrella portion of the proximal crimping portion and the back surface of the plate-shaped portion is not ultrasonically joined. Specifically, as shown in Fig. 10, it is preferable that the first crimping portion 28 whose center O1 is closer to the center O3 of the current collecting portion 35, which is subjected to a larger external force than the busbar joint 27c, is the proximal crimping portion, and that the interface between the umbrella portion 28b of the first crimping portion 28 and the back surface 32b of the plate-shaped portion 32 is not ultrasonically joined, but that the interface between the umbrella portion 29b of the second crimping portion 29 and the back surface 32b of the plate-shaped portion 32 is ultrasonically joined. In this way, by adopting a configuration in which the first crimping portion 28 close to the current collecting portion 35 is made a proximal crimping portion and the first crimping portion 28 and the plate-shaped portion 32 are not ultrasonically joined, the large external force acting on the current collecting portion 35 can be preferentially absorbed by the first crimping portion 28, and damage to the joint between the second crimping portion 29 and the plate-shaped portion 32 can be suppressed.

[0063] [2] In the above embodiment, the negative electrode external terminal 26 is made of aluminum, and the negative electrode current collector terminal 31 is made of copper. However, the present invention is not limited to this. The material of the negative electrode external terminal 26 may be an aluminum alloy, and the material of the negative electrode current collector terminal 31 may be a copper alloy. Alternatively, the material of the negative electrode external terminal 26 and the negative electrode current collector terminal 31 may be various metals or alloys having good electrical conductivity, depending on the materials of the electrode body 20 and the bus bar B.

[0064] [3] In the above embodiment, the positive terminal PS has two crimping portions, the center of which overlaps with the busbar joint when viewed in the Z-axis direction, and the interface between the umbrella portion of the crimping portion close to the current collector and the back surface of the plate-like portion is not ultrasonically welded, while the interface between the umbrella portion of the other crimping portion and the back surface of the plate-like portion is ultrasonically welded. However, the present invention is not limited to such an embodiment. The positive terminal PS is a member in which the positive external terminal 25 and the positive current collector terminal 30 are made of the same metal material, in other words, they are not dissimilar material joining members. Therefore, the positive terminal PS may be a member in which the crimping portion and the plate-like portion are joined by laser welding instead of ultrasonic welding. In this case, even if one crimping portion and the plate-like portion are laser-welded to each other and then the other crimping portion and the plate-like portion are laser-welded to each other, the joint will not be damaged as in the case of joining by ultrasonic welding. Therefore, in the case of the positive electrode terminal PS, when the crimping portion and the plate-like portion are joined by laser welding or the like, both of the two crimping portions may be joined to the plate-like portion. The positive electrode terminal PS may be configured as a single member in which the positive electrode external terminal and the positive electrode current collector terminal are integrally formed.

[0065] [4] In the above embodiment, the center O3 of the current collecting portion 35 is synonymous with the position of the center of gravity of the current collecting portion 35 as viewed in the Z-axis direction, and the positional relationship between the current collecting portion 35 and each of the crimped portions 28, 29 is specified by the distance from the center O3 of the current collecting portion 35 to the centers O1, O2 of the crimped portions 28, 29. However, the present invention is not limited to such an embodiment. The positional relationship between the current collecting portion 35 and each of the crimped portions 28, 29 may be specified, for example, by the center of a circle circumscribing the outer shape of the current collecting portion 35 as viewed in the Z-axis direction and the positions of the centers O1, O2 of the crimped portions 28, 29, or by the positions of the joints between the electrode connection portion 35c of the current collecting portion 35 and the electrode body 20 as viewed in the Z-axis direction and the positions of the centers O1, O2 of the crimped portions 28, 29.

[0066] In addition, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided no contradiction arises. Furthermore, the embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention. [Explanation of symbols]

[0067] 1: Secondary battery 11: Case body (housing) 12: Sealing plate (lid body) 20: Electrode body 25: Positive external terminal 26: Negative electrode external terminal (first member) 27: Plate-shaped portion (first plate-shaped portion) 27c: Busbar joint 28: First crimping part (crimping part) 28a:Shaft part 28b: Umbrella part 29: Second crimping part (crimping part) 29a:Shaft part 29b: Umbrella part 30: Positive collector terminal 31: Negative electrode collector terminal (second member) 32: Plate-shaped portion (second plate-shaped portion) 33: 1st through hole (hole) 34: 2nd through hole (hole) 35: Current collector PS:Positive terminal NS: Negative terminal (battery terminal) B: Bus bar

Claims

1. A battery terminal having a first member and a second member made of metal, The first member is A first plate-shaped portion, at least a part of a surface of which is a bus bar joint portion; The first plate-shaped portion has a shaft portion and a head portion, and two crimping portions are formed on a rear surface of the first plate-shaped portion. The second member is A second plate-shaped portion having two holes formed therein penetrating from the front to the back; A current collecting portion provided in connection with a rear surface of the second plate-shaped portion, Each of the crimping portions is formed such that the shaft portion is located inside each of the holes and the umbrella portion extends over a rear surface of the second plate-shaped portion, a proximal crimping portion is a crimping portion that is close to a center of at least one of the bus bar joint portion and the current collecting portion when viewed in a direction perpendicular to the surface of the first plate-shaped portion, and an umbrella portion of the proximal crimping portion is not ultrasonically joined to the back surface of the second plate-shaped portion, The other crimped portion other than the adjacent crimped portion is a battery terminal in which an umbrella portion is ultrasonically bonded to the rear surface of the second plate portion.

2. The battery terminal according to claim 1 , wherein the adjacent crimping portion is a crimping portion whose center overlaps with the bus bar joint portion and whose center is close to the current collecting portion when viewed in a direction perpendicular to the surface of the first plate-shaped portion.

3. The battery terminal according to claim 1 , wherein the proximal crimping portion is a crimping portion whose center is closer to which of the bus bar joint portion and the current collecting portion is subjected to a greater external force when viewed in a direction perpendicular to the surface of the first plate portion.

4. an external force acting on the bus bar joint portion is greater than that acting on the current collecting portion; The battery terminal according to claim 3 , wherein the adjacent crimped portion is a crimped portion whose center overlaps with the bus bar joint portion when viewed in a direction perpendicular to the surface of the first plate-shaped portion.

5. The current collecting portion is subjected to a larger external force than the bus bar joint portion, The battery terminal according to claim 3 , wherein the proximal crimped portion is a crimped portion whose center is closer to the current collecting portion when viewed in a direction perpendicular to the surface of the first plate-shaped portion.

6. the first member is made of aluminum or an aluminum alloy; The battery terminal according to any one of claims 1 to 5, wherein the second member is made of copper or a copper alloy.

7. A housing having an opening; a cover for sealing an opening of the housing; An electrode body disposed within the housing; a battery terminal electrically connected to the electrode body, the battery terminal has a first member and a second member made of metal; The first member is A first plate-shaped portion, at least a part of a surface of which is a bus bar joint portion; The first plate-shaped portion has a shaft portion and a head portion, and two crimping portions are formed on a rear surface of the first plate-shaped portion. The second member is A second plate-shaped portion having two holes formed therein penetrating from the front to the back; A current collecting portion provided in connection with a rear surface of the second plate-shaped portion, Each of the crimping portions is formed such that the shaft portion is located inside each of the holes and the umbrella portion extends over a rear surface of the second plate-shaped portion, a proximal crimping portion is a crimping portion that is close to a center of at least one of the bus bar joint portion and the current collecting portion when viewed in a direction perpendicular to the surface of the first plate-shaped portion, and an umbrella portion of the proximal crimping portion is not ultrasonically joined to the back surface of the second plate-shaped portion, The other crimped portions other than the adjacent crimped portion have their umbrella portions ultrasonically bonded to the back surface of the second plate-shaped portion, A secondary battery in which the surface of the first plate-shaped portion is located outside the lid, and the current collecting portion is electrically connected to the electrode body inside the casing.

8. The secondary battery according to claim 7 , wherein a bus bar is joined to the bus bar joint portion.

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