Sealing element

Abstract

To provide a sealing element in which adhesion between a battery terminal and an insulating member made of resin is improved.SOLUTION: A sealing element includes a lid body 12 in which an attachment port 12a penetrating the front and back surfaces is formed, a battery terminal NS including a first member 26 made of metal having a bus bar welding surface B and a second member 31 ultrasonically bonded to the first member 26, and a resin member 37 made of resin that insulates the lid body 12 and the battery terminal NS from each other. The battery terminal NS has a plurality of knurled marks R formed on a surface of the first member 26 at positions corresponding to an ultrasonically bonded portions C. The insulating member 37 is formed by insert molding in a state of being integrated with the lid body 12 and the battery terminal NS so as to cover at least the ultrasonic bonding portion C between the first member 26 and the second member 31 and the plurality of knurled marks R and so as to fill a space between the attachment port 12a and the battery terminal NS.SELECTED DRAWING: Figure 2

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 an opening, 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, the 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 integrally molded so as to fill the space between the sealing plate and the battery terminals. Also, in this battery, the insulating member arranged around the battery terminals that protrude outside the electrode body is thin-walled, and is configured to be able to follow deformation of the battery terminals. [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, when a tensile force acts on the battery terminal in a direction away from the electrode body, a shear force acts on the interface between the battery terminal and the insulating member. Therefore, in a battery mounted on a vehicle, when vehicle vibrations or the like are transmitted to the battery, an external force acts on the battery terminal via a bus bar joined to the battery terminal to electrically connect multiple batteries, and the joint between the electrode terminal and the insulating member is likely to peel off. Therefore, the sealing body of the battery described in Patent Document 1 has room for improvement in terms of improving the adhesion between the electrode terminal and the resin insulating member.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a sealing body that improves adhesion between a battery terminal and a resin 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 second member ultrasonically joined to the first member; a resin insulating member that insulates the lid body from the battery terminals, the battery terminal has a plurality of knurled marks formed on a surface of the first member at locations corresponding to ultrasonic bonding locations; The insulating member is formed by insert molding so as to cover at least the ultrasonic bonding point between the first member and the second member and the plurality of knurling marks, and to be integral with the cover body and the battery terminal so as to fill the gap between the mounting opening and the battery terminal.

[0008] According to the above characteristic configuration, the battery terminal of the sealing body and the insulating member are integrated with each other in a state where the resin insulating member is impregnated into the minute irregularities caused by the knurling marks formed on the surface of the first member. In other words, the first member constituting the battery terminal and the insulating member integrated with the first member have a large contact area due to the knurling marks on the surface of the first member, improving the adhesion of the insulating member to the battery terminal. This makes it easier to maintain good adhesion between the insulating member and the battery terminal, even when an external force is applied to the insulating member or the battery terminal, making it difficult for moisture to penetrate the interface between them. As a result, moisture can be prevented from penetrating the ultrasonically bonded portion between the first and second members of the battery terminal, suppressing corrosion of the battery terminal.

[0009] Further characteristic features of the sealing body according to the present invention are: a depth of the knurled mark is 20% or more and 80% or less of a maximum thickness of a portion of the first member where the knurled mark is formed, Each of the knurled peaks of the plurality of knurled marks has a conical or pyramidal shape, and the angle formed by the two sides leading to the apex is 30 degrees or more and 150 degrees or less.

[0010] According to the above characteristic configuration, the surface area of ​​the first member at the battery terminal for contacting the insulating member can be more appropriately secured. Therefore, the insulating member can easily penetrate between the multiple knurled marks formed on the surface of the first member, ensuring a sufficient contact area between the first member and the insulating member. This further improves the adhesion of the insulating member to the battery terminal.

[0011] Further characteristic features of the sealing body according to the present invention are: the first member has a base portion on a surface of which a busbar welding surface is set, and a flange portion extending from at least a part of a side surface of the base portion in a direction away from the side surface and having a surface recessed from the surface of the base, the second member has a flat surface facing the flange portion, The interface between the back surface of the flange portion of the first member and the surface of the flat portion of the second member is joined by ultrasonic bonding, and a plurality of the knurled marks are formed on the surface of the flange portion.

[0012] According to the above characteristic configuration, the first member of the battery terminal has a base and a flange that is thinner than the base, and the surface of the flange on which the knurling marks are formed can be covered with a resin insulating member. This allows the insulating member to be placed on the surface of the flange while leaving a portion of the battery terminal (for example, the busbar welding surface) exposed to the outside. As a result, the sealing body can be configured compactly.

[0013] Further characteristic features of the sealing body according to the present invention are: Each knurling peak of the plurality of knurling marks is conical or pyramidal, and among the plurality of knurling marks, the knurling mark formed near the base has a larger angle formed between the two sides leading to the top of the knurling peak, or a deeper knurling mark, than the knurling mark formed at a position farther from the base.

[0014] When the first member of a battery terminal has a base and a flange, and a bus bar is joined to the bus bar welding surface, the insulating member is most likely to peel off at the portion of the flange closest to the base when an external force due to vehicle vibration or the like acts on the bus bar of a secondary battery mounted on a vehicle. Therefore, in this configuration, among the multiple knurling marks, the knurling marks formed near the base have a larger angle or a deeper depth than the knurling marks formed farther from the base. This makes it easier to ensure a contact area between the insulating member and the first member near the base, where a force that would peel the insulating member from the battery terminal is more likely to be applied when an external force acts on the bus bar joined to the bus bar welding surface of the base. As a result, the insulating member is less likely to peel off from the first member in the sealing body. [Effects of the Invention]

[0015] As described above, the sealing body according to the present invention can improve the adhesion between the battery terminal and the insulating member. [Brief explanation of the drawings]

[0016] [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] 5A to 5C are schematic diagrams illustrating a manufacturing process of a negative electrode battery terminal. [Figure 4] FIG. 2 is an enlarged view of a main part of the sealing body of the first embodiment. [Figure 5] FIG. 10 is a diagram for explaining the angle of the knurling marks. [Figure 6] FIG. 4 is an enlarged view of a main part of a sealing body according to a first modified example of the first embodiment. [Figure 7] FIG. 10 is an enlarged view of a main part of the sealing body according to Modification 1 of the first embodiment when an external force is applied thereto. [Figure 8] 7 is a diagram for explaining the force acting on the sealing member shown in FIG. 6. FIG. [Figure 9] FIG. 10 is an enlarged view of a main part of a sealing body in which the angle of the knurled marks is constant. [Figure 10] FIG. 10 is an enlarged view of a main part of a sealing body having knurled marks at a constant angle when an external force is applied. [Figure 11] 10 is a diagram for explaining the force acting on the sealing member shown in FIG. 9. FIG. [Figure 12] FIG. 10 is an enlarged view of a main part of a sealing body according to Modification 2 of the first embodiment. [Figure 13] FIG. 10 is an enlarged view of a main part of the sealing body of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] 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.

[0018] [Overview of Secondary Battery 1] 1 is an exploded perspective view of a secondary battery 1 equipped with a sealing body 2 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.

[0019] 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.

[0020] [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."

[0021] 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.

[0022] [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.

[0023] 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).

[0024] [Configuration of sealing body 2] Next, the detailed structure of the sealing body 2 will be described with reference to Figures 1 and 2. Figure 2 is a schematic vertical cross-sectional view taken along line II-II in Figure 1.

[0025] 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.

[0026] 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).

[0027] 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).

[0028] 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.

[0029] The structure of the negative electrode side will be described below with reference to Figures 2 to 5. Figure 3 is a schematic diagram for explaining the manufacturing process of the negative electrode battery terminal NS, and Figure 4 is an enlarged view of the main part of Figure 2. Figure 5 is a diagram for explaining the angle of the knurling marks R.

[0030] 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 has a base 27 and a flange 28. A bus bar welding surface B is defined on a surface 27a of the base 27. The flange 28 extends from at least a part of a side surface 27b of the base 27 in a direction away from the side surface 27b, and the surface 28a is recessed from the surface 27a of the base 27. The surface 27a of the base 27 functions as a bus bar joint to which an aluminum bus bar is welded. In this embodiment, the flange 28 is joined to a flat portion 32 of a negative electrode current collector terminal 31, which will be described later.

[0031] 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."

[0032] In this embodiment, the negative electrode current collector terminal 31 has a flat 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 32a of the flat portion 32.

[0033] In this embodiment, the current collecting portion 35 is a member that extends downward from the back surface 32a of the flat portion 32 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 32a of the flat portion 32 of the negative electrode current collecting terminal 31. In addition, the lower end of the current collecting portion 35 has an electrode connection portion 35a to which the negative electrode terminal connection portion 22 of the electrode body 20 is joined.

[0034] In this way, the negative battery terminal NS, which is made up of the negative external terminal 26 and the negative current collector terminal 31, is a dissimilar material joined member made up of 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 ultrasonic welding. This ensures electrical continuity between the negative external terminal 26 and the negative current collector terminal 31. On the front surface (surface 28a (see FIG. 3)) of the flange portion 28 of the negative external terminal 26, there are multiple knurled marks R formed by pressing the horn H against it during ultrasonic welding.

[0035] 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 knurling marks R formed on the surface 28a of the flange portion 28 and fill the gap between the negative electrode battery terminal NS and the mounting opening 12a of the sealing plate 12.

[0036] 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.

[0037] On the positive electrode side of this embodiment, the positive electrode battery terminal PS is different from the negative electrode battery terminal NS, which is a dissimilar material joining member, in that 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), are appropriately joined by ultrasonic welding.

[0038] 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 generally rectangular flat portion when viewed in the Z-axis direction and a plate-shaped current collector 34 extending downward from the back surface of the flat portion. An electrode connection portion 34a at the end of the current collector 34 is joined to the positive electrode terminal joint 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."

[0039] [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 with reference to Figure 3, taking the negative electrode battery terminal NS as an example.

[0040] Specifically, in this embodiment, an ultrasonic bonding device including a horn H and an anvil A is used. The horn H resonates with ultrasonic vibrations emitted from the oscillator and applies vibrations of a frequency equal to or higher than the ultrasonic frequency range to the object, and the anvil A is a base that supports the object. FIG. 3 only shows the positional relationship between the flange portion 28 and the negative electrode current collector terminal 31, and the anvil A and horn H. As shown in FIG. 3, in this embodiment, the flange portion 28 of the negative electrode external terminal 26 is disposed above the negative electrode current collector terminal 31, the anvil A is disposed below the flat portion 32 of the negative electrode current collector terminal 31, and the horn H is disposed above the flange portion 28 of the negative electrode external terminal 26.

[0041] First, the anvil A is pressed against the back surface 32a of the flat portion 32 of the negative electrode current collector terminal 31, and the horn H is pressed against the surface 28a of the flange portion 28 of the negative electrode external terminal 26 in the vertical direction (Z-axis direction) to apply pressure. Note that, in this embodiment, the horn H used has a tip end surface with a rectangular ring shape, but is not limited to this.

[0042] Next, ultrasonic vibrations are applied by the horn H in a direction parallel to the surface 28a of the flange portion 28 (a direction perpendicular to the pressure direction), thereby joining the interface between the negative electrode external terminal 26 and the negative electrode current collector terminal 31. The tip of the horn H has projections and depressions formed on the portion facing the surface 28a of the flange portion 28 for forming knurling marks R, which will be described later.

[0043] In this way, as shown in Fig. 4, the interface between the back surface of the flange portion 28 of the negative electrode external terminal 26 and the surface of the flat portion 32 of the negative electrode current collector terminal 31 is ultrasonically joined. In addition, a plurality of knurling marks R are formed on the surface 28a of the flange portion 28 at locations corresponding to the ultrasonic joining locations C. Furthermore, as shown in Fig. 5, each of the plurality of knurling marks R1 has a quadrangular pyramid shape.

[0044] Next, the process of integrating the sealing plate 12 and the negative battery terminal NS by insert molding the negative electrode insulating member 37 will be described using the negative electrode insulating member 37 as an example.

[0045] 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.

[0046] 4, the ultrasonic bonding area C between the negative external terminal 26 and the negative current collector terminal 31 and the multiple knurling marks R are covered by 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 mounting opening 12a of the sealing plate 12 and the negative battery terminal NS.

[0047] As described above, in this embodiment, the battery terminal NS (PS) of the sealing body 2 and the insulating member (e.g., the negative electrode insulating member 37) are integrally molded with the knurled marks R formed on the surface 28a of the flange portion 28, impregnated with the resin insulating member (e.g., the negative electrode insulating member 37). That is, the knurled marks R on the surface 28a of the external terminal 26 (25) ensure a large contact area with the insulating member 37, thereby improving the adhesion of the insulating member 37 to the battery terminal NS (PS). This facilitates maintaining a good bond between the insulating member and the battery terminal NS (PS), even when an external force is applied to the insulating member or the battery terminal NS (PS), and reduces the penetration of moisture into the interface between them. As a result, moisture is prevented from penetrating the ultrasonic bonded portion C between the external terminal 26 (25) and the current collecting terminal 31 (30) in the battery terminal NS (PS), thereby suppressing corrosion of the battery terminal NS (PS).

[0048] 4, the width of the knurling marks R is represented by W, the depth of the knurling marks R is represented by D, and the thickness of the flange portion 28 on which the knurling marks R are formed is represented by T. Here, the depth D of the knurling marks R is the distance inward in a direction perpendicular to the surface 28a of the flange portion 28.

[0049] 5, the angle of the knurling mark R1 is represented by θ. Each knurling peak (knurling mark R1) of the multiple knurling marks R is conical or pyramidal (the knurling mark R1 in FIG. 5 is a quadrangular pyramidal), and the angle θ of the knurling mark R refers to the angle formed by the two sides R1a, R1a of each knurling peak of the multiple knurling marks R (for example, the knurling mark R1 in FIG. 5) facing the apex P.

[0050] From the viewpoint of increasing the contact area between the flange portion 28 and the negative electrode insulating member 37 as much as possible, the depth D of the knurling marks R and the angle θ of the knurling marks R are preferably within a predetermined range. For example, the depth D of the knurling marks R is preferably 20% to 80% of the thickness T, which is the maximum thickness of the portion of the flange portion 28 where the knurling marks R are formed. The angle θ of the knurling marks R is preferably 30 degrees to 150 degrees, and more preferably 45 degrees to 135 degrees. If the width W of the knurling marks R is too narrow, the resin will not easily penetrate the knurling marks R, making it difficult to ensure a sufficient contact area between the flange portion 28 and the negative electrode insulating member 37. Therefore, the width W of the knurling marks R is preferably 20 μm or more. Note that while the negative electrode side has been described as an example with reference to FIGS. 4 and 5, the same applies to the positive electrode side.

[0051] [Modification 1 of the First Embodiment] In the above embodiment, an example was shown in which the angle θ of the multiple knurling marks R was constant, but a configuration in which the angle θ of the multiple knurling marks R varied may also be used. Specifically, as shown in FIG. 6, in sealing body 2 in Modification 1, knurling marks R1, R2, and R3 are formed in this order from side surface 27b of base 27 along a direction away from base 27. Here, angle θ1 of knurling mark R1 closer to base 27 is larger than angle θ2 of knurling mark R3 farther from base 27. Note that in FIG. 6, angles θ1 and θ2 of knurling marks R1 and R3 are shown as being equivalent to angles of grooves formed between multiple knurling marks R1 to R3.

[0052] Here, as shown in FIG. 7, when an external force in the Z-axis direction acts on the negative electrode external terminal 26, as shown in FIG. 8, a force “F” acting orthogonally to the surface 28a of the flange portion 28 and directed outward acts on the negative electrode insulating member 37. Further, a force “f” acting orthogonally to the surface 28a of the flange portion 28 and directed inward acts on the negative electrode external terminal 26. Here, a plurality of knurling marks R are formed on the surface 28a of the flange portion 28, and the knurling mark R1 has an angle θ1. Therefore, the shearing force S1 acting between the negative electrode external terminal 26 and the negative electrode insulating member 37 on the side closer to the base portion 27 than the knurling mark R1 is “Fcosθ3”. Note that the angle θ3 is “θ1 / 2”.

[0053] On the other hand, in the sealing body 2 in which a plurality of knurling marks R1 to R4 shown in FIG. 9 are constant at an angle θ2 (θ2 < θ1), as shown in FIG. 10, when an external force in the Z-axis direction acts on the negative electrode external terminal 26, as shown in FIG. 11, a force “F” acting orthogonally to the surface 28a of the flange portion 28 and directed outward acts on the negative electrode insulating member 37. Further, a force “f” acting orthogonally to the surface 28a of the flange portion 28 and directed inward acts on the negative electrode external terminal 26. Here, a plurality of knurling marks R are formed on the surface 28a of the flange portion 28, and the knurling mark R1 has an angle θ2. For this reason, the shearing force S2 acting between the negative electrode external terminal 26 and the negative electrode insulating member 37 is “Fcosθ4”. Note that the angle θ4 is “θ2 / 2”.

[0054] The angle θ1 of the knurling mark R1 (the angle θ1 of the groove portion in the knurling mark R) in the sealing body 2 shown in FIG. 7 is larger than the angle θ2 of the knurling mark R1 (the angle θ2 of the groove portion) in the sealing body 2 shown in FIG. 10. From this, since “Fcosθ3” is smaller than “Fcosθ4”, the relationship “S1 < S2” holds. That is, by increasing the angle θ (the angle of the groove portion) of the knurling mark R, the shearing force acting between the negative electrode external terminal 26 and the negative electrode insulating member 37 can be reduced.

[0055] On the other hand, for the multiple knurling marks R in the Y direction (all of the knurling marks), the larger the angle θ of the knurling marks R, the smaller the contact area between the negative external terminal 26 and the negative insulating member 37. Therefore, if the angle θ of the knurling marks R is increased across the entire area of ​​the knurling marks R, the force in the shearing direction can be reduced, but the contact area is reduced, resulting in a decrease in adhesion between the negative external terminal 26 and the negative insulating member 37. Therefore, in Modification 1, the angle θ1 of the knurling marks R1 closer to the base 27 is made larger than the angle θ2 of the knurling marks R3 farther from the base 27. This makes it possible to ensure a sufficient contact area between the negative external terminal 26 and the negative insulating member 37 while reducing the force in the shearing direction acting on the interface between the negative external terminal 26 and the negative insulating member 37 in the vicinity of the base 27, where the negative insulating member 37 is more likely to peel off from the negative external terminal 26. This makes it less likely for the insulating member 37 to peel off when an external force is applied to the negative external terminal 26. Although the first modification of the first embodiment has been described with reference to FIGS. 6 to 11 by taking the negative electrode side as an example, the same applies to the positive electrode side.

[0056] [Modification 2 of the First Embodiment] The depth D of the knurling marks R may vary. Specifically, as shown in Fig. 12, in sealing body 2 in modification 2, depth D1 of the knurling marks R on the side closer to base 27 is greater than depth D2 of the knurling marks R on the side farther from base 27.

[0057] With this configuration, when an external force acts on the negative external terminal 26, the contact area between the negative external terminal 26 and the negative insulating member 37 increases on the side closer to the base 27 where a force that peels the negative external terminal 26 from the negative external terminal 26 is more likely to act, improving adhesion therebetween. As a result, when an external force acts on the negative external terminal 26, peeling of the insulating member 37 is suppressed even on the side closer to the base 27. Note that while the second modification of the first embodiment has been described with reference to FIG. 12 using the negative electrode side as an example, the same applies to the positive electrode side.

[0058] Second Embodiment As shown in FIG. 13 , in the second embodiment, a side surface portion 29 that is frame-shaped in a bottom view extends downward from the back surface of the base portion 27 of the negative electrode external terminal 26. The negative electrode current collector terminal 31 has a first portion 32A that extends along the side surface portion 29 of the negative electrode external terminal 26 and a second portion 32B that extends along the base portion 27 of the negative electrode external terminal 26. In this embodiment, the sealing body 2 has a plurality of knurling marks R formed on the surface 29 a of the side surface portion 29 of the negative electrode external terminal 26. The sealing body 2 of the second embodiment also increases the contact area between the negative electrode external terminal 26 and the negative electrode insulating member 37, improving the adhesion therebetween. Note that, although the second embodiment has been described using the negative electrode side as an example with reference to FIG. 13 , the positive electrode side is similarly described.

[0059] [Another embodiment] [1] 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, but the present invention is not limited to this. The negative electrode external terminal 26 and the negative electrode current collector terminal 31 may be made of copper. Alternatively, the negative electrode external terminal 26 and the negative electrode current collector terminal 31 may be made of various metals or alloys with good electrical conductivity, as appropriate, depending on the materials of the electrode body 20 and the bus bar.

[0060] 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]

[0061] 1: Secondary battery 2: Sealing body 12: Sealing plate (lid body) 25: Positive external terminal (first member) 26: Negative electrode external terminal (first member) 27: Base 27a: Surface 27b: Side 28: Flange part 28a: Surface 30: Positive electrode current collecting terminal (second member) 31: Negative electrode current collecting terminal (second member) 37: Insulating material C: Ultrasonic joint D, D1, D2: Depth NS: Negative battery terminal (battery terminal) PS: Positive battery terminal (battery terminal) R: Knurling marks T: Thickness θ,θ1,θ2: angles

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 second member ultrasonically joined to the first member; a resin insulating member that insulates the lid body from the battery terminals, the battery terminal has a plurality of knurled marks formed on a surface of the first member at locations corresponding to ultrasonic bonding locations; The insulating member is a sealing body formed by insert molding, which covers at least the ultrasonic bonding point between the first member and the second member and the plurality of knurling marks, and is integral with the lid body and the battery terminal so as to fill the space between the mounting opening and the battery terminal.

2. a depth of the knurling marks is 20% or more and 80% or less of a maximum thickness of a portion of the first member where the knurling marks are formed, 2. The sealing body according to claim 1, wherein each of the knurling peaks of the plurality of knurling marks is conical or pyramidal, and the angle formed by the two sides leading to the apex is 30 degrees or more and 150 degrees or less.

3. the first member has a base portion on a surface of which a bus bar welding surface is set, and a flange portion extending from at least a part of a side surface of the base portion in a direction away from the side surface and having a surface recessed from the surface of the base, the second member has a flat surface portion facing the flange portion, 3. The sealing body according to claim 1, wherein the interface between the back surface of the flange portion of the first member and the surface of the planar portion of the second member is joined by ultrasonic bonding, and a plurality of the knurled marks are formed on the surface of the flange portion.

4. Each of the knurled peaks of the plurality of knurled marks is conical or pyramidal, 4. The sealing body according to claim 3, wherein, of the plurality of knurling marks, the knurling mark formed near the base has a larger angle formed between two sides of the knurled peak toward the apex or a deeper depth than the knurling mark formed at a position farther from the base.

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