sealing body

Abstract

A sealing body that improves adhesion between a battery terminal and a resin insulating member is provided. [Solution] The sealing body (2) comprises a lid (12), a metal first member (26) having a busbar welding surface (B), a battery terminal including a metal second member (31) including a plate-shaped portion (34) joined to the first member (26), and a resin insulating member (37) that insulates the lid (12) from the battery terminal, the plate-shaped portion (34) of the second member (31) having a convex portion (32) whose tip is joined to the back surface (28b) of the first member (26), and a flange portion (33) whose surface (33a) is separated from the first member (26) and extends around the convex portion (32) in a direction away from the convex portion (32), the flange portion (33) having a roughened portion (D) formed on at least a portion of its outer surface, the insulating member (37) being formed by insert molding integrally with the lid (12) and the battery terminal so as to cover at least the roughened portion (D) of the flange portion (33), and the cross-sectional area (S2) in the plate thickness direction of the flange portion (33) is greater than the maximum planar cross-sectional area (S1) of the convex portion (32).

Description

[Technical Field]

[0001] The present invention relates to a sealing body for a secondary battery. [Background technology]

[0002] In recent years, batteries such as lithium-ion secondary batteries have been suitably used as power sources for driving vehicles such as electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). This type of battery includes, for example, a lid attached to the opening of a battery case, battery terminals exposed to the outside through holes in the lid, and a resin insulating member that insulates the lid from the battery terminals. An example of a battery with this configuration is disclosed in Patent Document 1 below.

[0003] In the battery described in Patent Document 1, a sealing body arranged to seal the opening of the battery case includes a lid (sealing plate), battery terminals, and an insulating member, and the insulating member is provided so as to fill the gap between the sealing plate and the battery terminals and is integrally molded. In addition, in this battery, a current collector terminal included in the battery terminal has a recess formed in a position close to the location where the terminal mounting hole is formed in the lid, and the recess is filled with a resin insulating member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-15661 Summary of the Invention [Problem to be solved by the invention]

[0005] In the battery described in Patent Document 1, the cross-sectional area of ​​the current collector terminal at the portion including the recess is smaller than that of the portion not including the recess. Therefore, the amount of heat generated per unit area during current flow is greater in the portion including the recess than in the portion not including the recess. If the portion of the insulating member adjacent to the recess is used as a seal, the seal may be damaged by the increased amount of heat generated, causing the seal to malfunction. Therefore, the sealing body of the battery described in Patent Document 1 has room for improvement in terms of ensuring the effective function of the seal disposed between the current collector terminal and the insulating member included in the battery terminal.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a sealing body that can effectively function a seal portion disposed between a current collecting terminal included in a battery terminal and an insulating member. [Means for solving the problem]

[0007] The sealing body according to the present invention for achieving the above object has the following characteristic configuration: A sealing body for a sealed secondary battery that is attached to an opening of a housing, A lid body having an attachment opening formed therein that penetrates from the front to the back; a battery terminal including a metal first member having a bus bar welding surface and a metal second member including a plate-shaped portion and joined to the first member; a resin insulating member that insulates the lid body from the battery terminals, the plate-like portion of the second member has a convex portion whose tip end is joined to the back surface of the first member, and a flange portion whose front surface is spaced apart from the first member and which is provided around the convex portion and extends in a direction away from the convex portion, The flange portion has a roughened portion formed on at least a part of an outer surface thereof, the insulating member is formed by insert molding in a state where it is integrated with the lid body and the battery terminal so as to cover at least the roughened portion of the flange portion and fill the gap between the mounting opening and the battery terminal, The cross-sectional area of ​​the flange portion in the plate thickness direction is larger than the maximum planar cross-sectional area of ​​the protrusion.

[0008] According to the above characteristic configuration, the cross-sectional area of ​​the flange portion is larger than the maximum planar cross-sectional area of ​​the convex portion. Therefore, the amount of heat generated during current flow is smaller in the flange portion than in the convex portion. This suppresses temperature rise in the insulating member and reduces the strength reduction of the insulating member in the seal portion formed by impregnating the roughened portion of the flange portion with the resin of the insulating member. Therefore, the deterioration of the functionality of the seal portion formed by the roughened portion of the flange portion and the insulating member can be suppressed. As a result, the seal portion disposed between the battery terminal and the resin insulating member in the sealing body can function properly.

[0009] Further characteristic features of the sealing body according to the present invention are: the second member has the flange portion and the protruding portion formed of separate members, The electrical conductivity of the first component that constitutes the flange portion is lower than the electrical conductivity of the second component that constitutes the protrusion portion.

[0010] According to the above-described characteristic configuration, when a current is applied to the sealing body, the current flows less easily through the flange portion than through the protrusion portion. This reduces the amount of heat generated by the flange portion compared to the protrusion portion. As a result, the function of the seal portion formed by the roughened portion of the flange and the insulating member can be more easily maintained.

[0011] Further characteristic features of the sealing body according to the present invention are: The area of ​​the joint surface between the rear surface of the first member and the protrusion of the second member is smaller than the minimum cross-sectional area of ​​the second member.

[0012] According to the above characteristic configuration, when current is applied, the joint between the first and second members generates the most heat and experiences the highest temperature rise. Here, the joint is surrounded by an insulating member, making it difficult for the joint to dissipate heat. Therefore, when a large current occurs between the first and second members, the joint can be melted. As a result, when a large current occurs, the sealing body can cut off the current path at the joint, thereby suppressing abnormal heat generation in the secondary battery. [Effects of the Invention]

[0013] As described above, the sealing member according to the present invention allows the seal portion disposed between the current collector terminal included in the battery terminal and the insulating member to function effectively. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an exploded perspective view of a secondary battery according to an embodiment; [Figure 2] FIG. 2 is a schematic longitudinal sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a schematic rear view of the sealing body. [Figure 4] FIG. 10 is a schematic rear view of a modified example of the first embodiment. [Figure 5] FIG. 10 is a schematic vertical cross-sectional view of a sealing body of a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] A sealing body according to one embodiment of the present invention will be described below with reference to the drawings. Note that the following description will be given taking a lithium ion secondary battery equipped with the sealing body as an example. In addition, the following description and drawings will be simplified as appropriate for clarity of explanation.

[0016] [Overview of Secondary Battery 1] 1 is an exploded perspective view of a secondary battery 1 equipped with a sealing body according to this embodiment. In the following description, the direction parallel to the height direction of the secondary battery 1 is referred to as the Z-axis direction, the direction parallel to the longitudinal direction of the electrode body 20 is referred to as the X-axis direction, and the direction parallel to the thickness direction of the electrode body 20 is referred to 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.

[0017] 1, the secondary battery 1 includes a battery case 10 made up of a case body 11 and a sealing plate 12 that constitutes a sealing body 2, battery terminals PS and NS made up of metal external terminals 25 and 26 and current collector terminals 30 and 31, and an electrode body 20. The secondary battery 1 is a sealed secondary battery in which the electrode body 20, the current collector terminals 30 and 31, etc. are housed inside the case body 11, the opening of the case body 11 is sealed with the sealing plate 12, and an electrolyte is poured into the inside of the case body 11.

[0018] [Configuration of battery case 10] As shown in FIG. 1 , the battery case 10 is composed of a case body 11 that is roughly rectangular and has an open top, and a sealing plate 12 that seals the opening of the case body 11. In the battery case 10 of this embodiment, the case body 11 as a housing and the sealing plate 12 as a lid are both made of aluminum, but this is not limited to this. The materials for the case body 11 and the sealing plate 12 may be selected from various metals and alloys depending on the type and application of the battery. In this embodiment, the sealing plate 12 corresponds to the "lid."

[0019] As will be described in detail later, sealing plate 12 constitutes a part of sealing body 2. In this embodiment, sealing plate 12 has a shape corresponding to the shape of the opening of case body 11 and is configured to be able to seal the opening of case body 11.

[0020] [Configuration of electrode body 20] In this embodiment, the electrode assembly 20 is formed as a wound assembly in which long strip-shaped positive and negative electrode materials are stacked with a strip-shaped separator interposed therebetween, wound, and compressed into a flat shape. As shown in FIG. 1 , the electrode assembly 20 of this embodiment is substantially rectangular when viewed in the thickness direction (Y-axis direction). At one end of the electrode assembly 20 in the longitudinal direction (X-axis direction) when viewed in the thickness direction, a positive electrode terminal joint 21 where the positive electrode material is gathered is formed, and at the other end, a negative electrode terminal joint 22 where the negative electrode material is gathered is formed. The structure of the electrode assembly 20 is not particularly limited, and various structures used in general sealed secondary batteries can be employed. 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.

[0021] In this embodiment, the electrode body 20 is covered with an insulating film and housed inside the case body 11 in an orientation in which the thickness direction and 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).

[0022] [First embodiment] [Configuration of sealing body 2] Next, the detailed configuration of the sealing body 2 will be described with reference to Figures 1 to 3. Figure 2 is a schematic vertical cross-sectional view taken along line II-II in Figure 1. Figure 3 is a schematic rear view of the sealing body 2 as viewed from the rear side.

[0023] As shown in FIGS. 1 and 2, the sealing body 2 includes a sealing plate 12, a positive battery terminal PS, a negative battery terminal NS, a positive electrode insulating member, and a negative electrode insulating member 37.

[0024] The sealing plate 12 is a plate-like member that seals the opening of the case body 11, and has two mounting openings 12a formed through its front and back surfaces (top and bottom surfaces). Specifically, the sealing plate 12 is made of a flat plate member that is generally rectangular when viewed in the Z-axis direction. The sealing plate 12 has the mounting opening 12a for the positive electrode formed at one end of its longitudinal ends (both ends in the X-axis direction), and the mounting opening 12a for the negative electrode formed at its other longitudinal end. The front surface of the sealing plate 12 faces the outside of the secondary battery 1, and the back surface faces the inside of the secondary battery 1 (in other words, the inside of the case body 11).

[0025] 1 and 2, the sealing body 2 of this embodiment includes, as its positive electrode side configuration, a positive battery terminal PS and a positive electrode insulating member attached to the attachment opening of the sealing plate 12, and as its negative electrode side configuration, a negative battery terminal NS and a negative electrode insulating member 37 attached to the attachment opening 12a. The positive electrode battery terminal PS and the negative electrode battery terminal NS are attached so that the respective bus bar welding surfaces B, which will be described later, are positioned on the surface side of the sealing plate 12 (in other words, on the external side of the secondary battery 1).

[0026] In the sealing body 2 of this embodiment, the positive electrode side and the negative electrode side have substantially the same configuration, but the materials of the external terminals and current collector terminals are different. Specifically, in this embodiment, the positive electrode external terminal 25 and the positive electrode current collector terminal 30 that constitute the positive electrode battery terminal PS are made of the same metal material. On the other hand, different metal materials are used for the negative electrode external terminal 26 and the negative electrode current collector terminal 31 that constitute the negative electrode battery terminal NS.

[0027] The structure of the negative electrode side will be described below with reference to FIG.

[0028] The negative electrode external terminal 26 is a terminal for external connection, and is a plate-like body that is generally rectangular when viewed in the Z-axis direction. In this embodiment, the negative electrode external terminal 26 is formed in a plate shape and has an upper surface member 27 and a lower surface member 28. A bus bar welding surface B is set on a surface 27a of the upper surface member 27. The upper surface member 27 is made of, for example, aluminum or an aluminum alloy. The lower surface member 28 is made of, for example, copper or a copper alloy. The surface 27a of the upper surface member 27 functions as the bus bar welding surface B to which an aluminum bus bar is welded. The upper surface member 27 and the lower surface member 28 are joined together by ultrasonic welding or the like.

[0029] The negative electrode current collector terminal 31 is a terminal for inputting and outputting electric power from the electrode body 20. The negative electrode current collector terminal 31 is disposed on the underside of the sealing plate 12, in other words, inside the case body 11. In this embodiment, the negative electrode current collector terminal 31 is made of copper. In this embodiment, the negative electrode external terminal 26 corresponds to the "first member," and the negative electrode current collector terminal 31 corresponds to the "second member."

[0030] In this embodiment, the negative electrode current collector terminal 31 includes a plate-shaped portion 34 that is generally rectangular when viewed in the Z-axis direction. The plate-shaped portion 34 has a protrusion 32 and a flange portion 33. The protrusion 32 has a tip portion 32a that faces the back surface 28b of the negative electrode external terminal 26 and a rising portion 32b that is continuous with the tip portion 32a. The protrusion 32 is formed as a protrusion that extends along the X-axis direction at the center of the plate-shaped portion 34 in a plan view, and has a hollow trapezoidal cross section in the YZ plane. The tip portion 32a of the protrusion 32 is joined to the back surface 28b of the bottom surface member 28 of the negative electrode external terminal 26. The surface 33a of the flange portion 33 is spaced from the bottom surface member 28 of the negative electrode external terminal 26 and extends around the protrusion 32 (on the outer circumferential side of the rising portion 32b) in a direction away from the protrusion 32 (in this embodiment, the Y-axis direction). The negative electrode current collector terminal 31 also has a plate-shaped current collector portion 35 extending downward from the rear surface 34a of the plate-shaped portion 34.

[0031] The flange portion 33 has a roughened portion D formed on at least a part of its outer surface. In this embodiment, the flange portion 33 has the roughened portion D formed on the surface 33a that faces the lower surface member 28 of the negative electrode external terminal 26 at a distance. Although a detailed description will be omitted, the roughened portion D is made up of countless minute protrusions formed on the outer surface of the flange portion 33, and is formed by, for example, performing a surface roughening treatment using a laser. Although not shown, the flange portion 33 may have a roughened portion formed on the side surface 33b.

[0032] In this embodiment, in the plate-shaped portion 34 of the negative electrode current collector terminal 31, the cross-sectional area S2 in the thickness direction (Z-axis direction) of the flange portion 33 is larger than the maximum planar cross-sectional area S1 of the protrusion 32. Here, the cross-sectional area S2 in the thickness direction of the flange portion 33 is defined as the cross-sectional area in the thickness direction of the portion of the flange portion 33 where the plate thickness is smallest. Furthermore, the maximum planar cross-sectional area S1 of the protrusion 32 is defined as the maximum value of the cross-sectional area in a plane perpendicular to the direction of current flow (arrow I in FIG. 2 ) from the current collector portion 35 of the current collector terminal 31 (second member) to the external terminal 26 (first member) (in this embodiment, the area of ​​a cross section approximately along the X-axis and Y-axis directions). Specifically, the maximum planar cross-sectional area S1 of the protrusion 32 is defined as the maximum value of the cross-sectional area in the thickness direction of the member constituting the rising portion 32b. 3, in a plan view (rear view) of the plate-shaped portion 34, the protrusion 32 is provided in the central portion, and the flange portion 33 is formed around the entire periphery of the protrusion 32. Therefore, the maximum planar cross-sectional area S1 of the protrusion 32 is the cross-sectional area in the plate thickness direction of the annular portion (the shaded portion in FIG. 3).

[0033] 2, the thickness T1 of the protrusion 32 is smaller than the thickness T2 of the flange 33. Therefore, in this embodiment, the cross-sectional area S2 of the flange 33 in the thickness direction (Z-axis direction) is certainly larger than the maximum planar cross-sectional area S1 of the protrusion 32. However, as long as the cross-sectional area S2 of the flange 33 in the thickness direction (Z-direction) is larger than the maximum planar cross-sectional area S1 of the protrusion 32, such as when the flange 33 is sufficiently larger than the protrusion 32 in terms of dimensions in a plan view, the thickness T1 of the protrusion 32 may be larger than the thickness T2 of the flange 33.

[0034] In this way, in the plate-shaped portion 34 of the negative electrode collector terminal 31, the cross-sectional area S2 of the flange portion 33 in the plate thickness direction (Z-axis direction) is larger than the maximum planar cross-sectional area S1 of the convex portion 32, so that the amount of heat generated when current is applied is smaller in the flange portion 33 than in the convex portion 32.

[0035] In this embodiment, the current collecting portion 35 is a member that extends downward from the back surface 34a of the plate-shaped portion 34 and has a bent portion in the middle. In other words, the current collecting portion 35 is provided so as to be connected to the back surface 34a of the plate-shaped portion 34 of the negative electrode current collecting terminal 31. In addition, the lower end of the current collecting portion 35 has an electrode connecting portion 35a to which the negative electrode terminal connecting portion 22 of the electrode body 20 is joined.

[0036] In this embodiment, the area S3 of the joint surface C between the back surface 28b of the negative external terminal 26 and the protrusion 32 of the negative current collector terminal 31 is smaller than the minimum cross-sectional area S4 of the current collector terminal 31. The minimum cross-sectional area S4 of the current collector terminal 31 is defined as the minimum value of the cross-sectional area in a plane perpendicular to the direction (arrow I in FIG. 2 ) of the current flowing to the external terminal 26 (first member). In this embodiment, the minimum cross-sectional area S4 of the current collector terminal 31 exists in the current collector portion 35, which has a smaller dimension than the plate-shaped portion 34 when viewed in the Z-axis direction, and specifically, is the cross-sectional area of ​​the current collector portion 35 in the XY plane.

[0037] In this way, the area S3 of the joint surface C between the back surface 28b of the negative electrode external terminal 26 and the protrusion 32 of the negative electrode current collector terminal 31 is smaller than the minimum cross-sectional area S4 of the current collector terminal 31, so that heat generation at the joint surface C (joint location) between the negative electrode external terminal 26 and the negative electrode current collector terminal 31 is greatest when current is applied. As a result, when a large current flows between the negative electrode external terminal 26 and the negative electrode current collector terminal 31, the joint location can be melted and broken, cutting off the current path. This prevents abnormal heat generation in the secondary battery 1.

[0038] The negative battery terminal NS, which is composed of the negative external terminal 26 and the negative current collector terminal 31, is a dissimilar material joined member including two members made of different metal materials. As will be described in detail later, the interface between the negative external terminal 26 and the negative current collector terminal 31 of the negative battery terminal NS is joined by, for example, laser welding or ultrasonic welding. This ensures electrical continuity between the negative external terminal 26 and the negative current collector terminal 31.

[0039] The negative electrode insulating member 37 is an insulating resin member. In this embodiment, the negative electrode insulating member 37 is a member made of PPS (polyphenylene sulfide) resin. The negative electrode insulating member 37 in this embodiment is formed integrally with the sealing plate 12 and the negative electrode battery terminal NS so as to cover the roughened portion D of the flange portion 33 and fill the gap between the mounting opening 12a and the negative electrode battery terminal NS.

[0040] In this embodiment, the negative battery terminal NS is inserted into the mounting opening 12a of the sealing plate 12, and then the negative insulating member 37 is insert-molded to integrate the negative battery terminal NS with the sealing plate 12 via the negative insulating member 37. The negative battery terminal NS and the sealing plate 12 are insulated by the negative insulating member 37, and the negative insulating member 37 maintains airtightness between the negative battery terminal NS and the mounting opening 12a of the sealing plate 12. The electrode connection portion 35a of the negative current collector terminal 31 is joined to the negative terminal joint portion 22 of the electrode body 20.

[0041] On the positive electrode side of this embodiment, the positive battery terminal PS differs from the negative battery terminal NS, which is a dissimilar material joining member, in that it is formed by appropriately joining a positive external terminal 25 and a positive current collector terminal 30, which are made of the same metal material (aluminum in this embodiment). In this embodiment, the positive external terminal 25 and the positive current collector terminal 30 both have the same outer shapes as the negative external terminal 26 and the negative current collector terminal 31. That is, the positive current collector terminal 30 includes a plate-shaped portion having a protrusion and a flange portion, and the tip of the protrusion is joined to the back surface of the positive external terminal 25. In addition, a roughened portion is formed on the flange portion.

[0042] Although details are omitted, on the positive electrode side of this embodiment, a positive electrode insulating member (not shown) is insert-molded with the positive electrode battery terminal PS inserted into the mounting opening of the sealing plate 12, and the positive electrode battery terminal PS is integrated with the sealing plate 12 via the positive electrode insulating member. As with the negative electrode side, the positive electrode battery terminal PS and the sealing plate 12 are insulated from each other by the positive electrode insulating member, and the positive electrode insulating member maintains airtightness between the positive electrode battery terminal PS and the mounting opening of the sealing plate 12. The positive electrode current collector terminal 30 has a plate-shaped portion that is generally rectangular when viewed in the Z-axis direction and a plate-shaped current collector portion 36 that extends downward from the back surface of the plate-shaped portion. The electrode connection portion 36a at the end of the current collector portion 36 is joined to the positive electrode terminal joint portion 21 of the electrode body 20. In this embodiment, the positive electrode external terminal 25 corresponds to the "first member," and the positive electrode current collector terminal 30 corresponds to the "second member."

[0043] As described above, in the secondary battery 1 of this embodiment, the amount of heat generated during current application is smaller in the flange portion 33 than in the protrusion 32, so that in the seal portion formed by impregnating the roughened portion D of the flange portion 33 with the resin of the negative electrode insulating member 37, a temperature rise in the negative electrode insulating member 37 is suppressed, and a decrease in the strength of the negative electrode insulating member 37 is suppressed. Therefore, a decrease in the function of the seal portion can be suppressed, and the seal portion disposed between the negative electrode battery terminal NS and the negative electrode insulating member 37 can function properly.

[0044] [Method for manufacturing sealing body 2] Next, a method for manufacturing the sealing body 2 according to this embodiment will be described. The method for manufacturing the sealing body 2 includes a step of manufacturing the battery terminals PS and NS, and a step of integrating the sealing plate 12 and the battery terminals PS and NS by molding an insert of an insulating member (e.g., negative electrode insulating member 37). The method for manufacturing the battery terminals PS and NS will be described using the negative electrode battery terminal NS as an example.

[0045] First, the lower surface member 28 of the negative electrode external terminal 26 and the protrusion 32 of the negative electrode current collector terminal 31 are joined together using an ultrasonic joining device or a laser joining device.

[0046] Next, the sealing plate 12 and the negative battery terminal NS are integrated by insert molding the negative electrode insulating member 37.

[0047] Specifically, in this embodiment, the sealing plate 12 and the negative battery terminal NS are placed in a cavity in a mold (not shown) so that the negative battery terminal NS is positioned within the attachment opening 12a of the sealing plate 12. Then, molten resin (PPS resin in this embodiment) is injected into the cavity through a gate, filling the cavity with the molten resin.

[0048] 2, the joint surface C between the negative external terminal 26 and the negative current collector terminal 31 and the roughened portion D are covered with the negative insulating member 37 formed by insert molding. In addition, the negative insulating member 37 is formed integrally with the sealing plate 12 and the negative battery terminal NS so as to fill the gap between the attachment opening 12a of the sealing plate 12 and the negative battery terminal NS.

[0049] [Modification 1 of the First Embodiment] In the above embodiment, an example has been shown in which the protrusion 32 is formed in the center of the plate-shaped portion 34 in a plan view. As shown in Fig. 4, the protrusion 32 may be formed over the entire area of ​​the plate-shaped portion 34 in the X-axis direction. By forming the protrusion 32 in this manner, the bonding surface C can be disposed long in the X-axis direction of the plate-shaped portion 34. As a result, the bonding strength between the negative electrode external terminal 26 and the negative electrode current collector terminal 31 can be increased.

[0050] Second Embodiment The second embodiment will be described mainly with respect to differences from the first embodiment. As shown in FIG. 5 , in the second embodiment, the negative electrode current collector terminal 31 is composed of two members. Specifically, in this embodiment, the flange portion 33 and the protrusion 32 of the negative electrode current collector terminal 31 are composed of separate members. The flange portion 33 is composed of a first component 38, and the protrusion 32 and the current collector 35 are composed of a second component 39. As shown in FIG. 5 , the second component 39 has the protrusion 32 formed by bending the second component 39 above the current collector 35. The first component 38 is joined to the second component 39 by laser welding or the like. In this embodiment, the cross-sectional area S2 of the flange 33 in the thickness direction is the cross-sectional area of ​​the first component 38 constituting the flange 33 at the minimum thickness. The maximum planar cross-sectional area S1 of the protrusion 32 is the maximum value of the cross-sectional area of ​​the second component 39 in the thickness direction at the portion constituting the protrusion 32.

[0051] Additionally, in this embodiment, the electrical conductivity of the first component 38 that constitutes the flange portion 33 is lower than the electrical conductivity of the second component 39 that constitutes the protrusion 32. In the sealing body 2 of this embodiment, the flange portion 33, which is made of a material that has a lower electrical conductivity than the protrusion 32, has a relatively lower current flow rate and generates less heat than the protrusion 32. Therefore, roughening the outer surface of the flange portion 33 to form a seal can suppress the temperature rise of the seal portion and the negative electrode insulating member 37 more effectively than roughening the outer surface of the protrusion 32 to form a seal portion.

[0052] Also in the second embodiment, the area S3 of the joint surface C between the back surface of the negative external terminal 26 and the protrusion 32 of the negative current collector terminal 31 is smaller than the minimum cross-sectional area S4 of the negative current collector terminal 31. As a result, when a large current flows between the negative external terminal 26 and the negative current collector terminal 31, the joint can be melted to cut off the current path, thereby suppressing abnormal heat generation in the secondary battery 1. Note that although the second embodiment has been described with reference to FIG. 5 using the negative electrode side as an example, the same applies to the positive electrode side.

[0053] [Another embodiment] [1] In the above embodiment, the negative electrode external terminal 26 is made of aluminum and copper, and the negative electrode current collector terminal 31 is made of copper. However, the present invention is not limited to this. The negative electrode external terminal 26 may be made of aluminum alone, and the negative electrode current collector terminal 31 may be made of copper, or both the negative electrode external terminal 26 and the negative electrode current collector terminal 31 may be made of copper. Furthermore, the negative electrode external terminal 26 and the negative electrode current collector terminal 31 may be made of various metals or alloys with good conductivity, as appropriate, depending on the materials of the electrode body 20 and the bus bar.

[0054] [2] In the above embodiment, the protrusion 32 is formed as a ridge extending along the X-axis direction and has a hollow trapezoidal cross section in the YZ plane, but the present invention is not limited to this. The shape of the protrusion may be a truncated cone or a truncated pyramid.

[0055] 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, as long as no contradiction arises. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Explanation of symbols]

[0056] 1: Secondary battery 2: Sealing body 12: Sealing plate (lid body) 25: Positive external terminal (first member) 26: Negative electrode external terminal (first member) 30: Positive electrode current collecting terminal (second member) 31: Negative electrode current collecting terminal (second member) 32: Convex part 33: Flange part 34: Plate-shaped part 37: Negative electrode insulating member (insulating member) C: Joint surface D: Roughened area NS: Negative battery terminal (battery terminal) PS: Positive battery terminal (battery terminal) S1: Cross-sectional area S2: Cross-sectional area S3: Area S4: Cross-sectional area

Claims

1. A sealing body for a sealed secondary battery that is attached to an opening of a housing, A lid body having an attachment opening formed therein that penetrates from the front to the back; a battery terminal including a metal first member having a bus bar welding surface and a metal second member including a plate-shaped portion and joined to the first member; a resin insulating member that insulates the lid body from the battery terminals, the plate-like portion of the second member has a convex portion whose tip end is joined to the back surface of the first member, and a flange portion whose front surface is spaced apart from the first member and which is provided around the convex portion and extends in a direction away from the convex portion, The flange portion has a roughened portion formed on at least a part of an outer surface thereof, the insulating member is formed by insert molding in a state where it is integrated with the lid body and the battery terminal so as to cover at least the roughened portion of the flange portion and fill the gap between the mounting opening and the battery terminal, The cross-sectional area of ​​the flange portion in the plate thickness direction is larger than the maximum planar cross-sectional area of ​​the protrusion.

2. The second member has the flange portion and the protruding portion formed of separate members, 2. The sealing body according to claim 1, wherein the electrical conductivity of the first component constituting the flange portion is lower than the electrical conductivity of the second component constituting the protrusion portion.

3. The sealing body according to claim 1 , wherein an area of ​​a joint surface between the back surface of the first member and the protruding portion of the second member is smaller than a minimum cross-sectional area of ​​the second member.

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