Method for manufacturing sealing body and sealing body

Abstract

To provide a method for manufacturing a sealing body that can realize a secondary battery in which the occurrence of defects in a resin member around a battery terminal is suppressed and the occurrence of poor welding when welding a bus bar to a bus bar welding surface is suppressed.SOLUTION: A method for manufacturing a sealing body includes an insert molding step of placing a cover body 13 in a mold, positioning a battery terminal NS in a mounting opening 15 of the cover body 13, and placing the surface side of a flat portion 31 in the mold so as to be in the mounting opening 15 of the cover body 13 and in the mold so as to abut the inner surface of the mold, and then filling a resin into the mold to mold an insulating member 40 integrally with the cover body 13 and the battery terminal NS so as to fill the space between the mounting opening 15 and the battery terminal NS, and a welding surface treatment step of processing the surface side of the flat portion 31 of the battery terminal NS such that the end face 42a downstream in the extension direction of the side wall portion 42 of the insulating member 40 protrudes beyond the busbar welding surface after the insert molding step.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a sealing body and a sealing body.

Background Art

[0002] Conventionally, secondary batteries such as nickel-metal hydride batteries and lithium-ion batteries have been used as power sources for electric vehicles, hybrid vehicles, and the like. As this type of secondary battery, for example, a sealed battery disclosed in Patent Document 1 is disclosed.

[0003] The sealed battery described in Patent Document 1 includes a battery case and an electrode body housed inside the battery case. In this sealed battery, the lid body constituting the battery case includes a sealing plate in which a mounting hole is formed, a positive electrode terminal member and a negative electrode terminal member attached to the mounting hole of the sealing plate, and is disposed between the sealing plate and each terminal member to insulate each terminal member from the sealing plate and to maintain the airtightness inside the battery. It has a sealing material for this purpose.

[0004] In the sealed battery described in Patent Document 1, the sealing material is formed in a state of being integrated with the sealing body and each terminal member by insert molding. Therefore, compared with a structure composed of two members in which the terminals are joined by caulking, the manufacturing cost is reduced by reducing the number of parts used in the battery.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, when a secondary battery is used as a power source for an electric vehicle or the like, generally, a battery module in which a plurality of secondary batteries are electrically connected to increase the charge / discharge capacity and output power is used. In this type of battery module, a plurality of secondary batteries are electrically connected via a bus bar welded so as to connect the positive and negative electrode terminals of adjacent secondary batteries, for example.

[0007] Here, in the sealed battery described in Patent Document 1, the upper end portions of the respective terminal members protrude beyond the upper end portion of the sealing material. Therefore, when welding a bus bar to the upper end portion of each terminal member, the bus bar is in close contact with the upper end surface of each terminal member. As a result, there is a risk of problems such as melting or heat sagging of resin members such as the sealing material disposed around each terminal member due to heat transfer from the bus bar.

[0008] Further, when the sealing material is formed integrally with the sealing plate and each terminal member by insert molding as in the sealed battery described in Patent Document 1, there is a risk that molten resin may penetrate between the upper end surface of each terminal member and the inner surface of the mold during insert molding. When the penetration of the molten resin occurs, burrs are generated on the upper end surface of each terminal member to which the bus bar is welded, and welding defects are likely to occur when welding the bus bar to the upper end surface.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing a sealing body and a sealing body that can realize a secondary battery in which the occurrence of problems in resin members around the battery terminals is suppressed and the occurrence of welding defects during welding of the bus bar to the bus bar welding surface is suppressed.

Means for Solving the Problems

[0010] The characteristic configuration of the method for manufacturing a sealing body according to the present invention for achieving the above object is as follows: A lid body having a mounting hole penetrating through the front and back; A battery terminal having a flat portion whose surface is a bus bar welding surface, and the bus bar welding surface is attached to the mounting hole of the lid body so as to be disposed on one side of the lid body; A method for manufacturing a sealing body for a sealed secondary battery, comprising: an insulating member made of resin having a side wall portion extending in a direction away from the lid along the flat portion of the battery terminal, and insulating the lid and the battery terminal. An insert molding step of disposing the lid in a mold, disposing the battery terminal in the mold in a state where the battery terminal is located in the mounting port of the lid and the surface side of the flat portion is in contact with the inner surface of the mold, filling the mold with resin, and molding the insulating member integrally with the lid and the battery terminal so as to fill the space between the mounting port and the battery terminal. A welding surface treatment step of performing a machining process on the surface side of the flat portion of the battery terminal after the insert molding step so that the end surface on the downstream side in the extending direction of the side wall portion of the insulating member protrudes more than the bus bar welding surface.

[0011] According to the above characteristic configuration, it is possible to simultaneously perform the process of making the end surface of the side wall portion of the insulating member protrude more than the bus bar welding surface and the removal of burrs generated due to the gap between the surface side of the flat portion and the inner surface of the mold during insert molding, and it is also possible to improve the flatness of the bus bar welding surface. That is, according to the above characteristic configuration, it is possible to easily manufacture a sealing body having a bus bar welding surface in which the end surface of the side wall portion of the insulating member protrudes more than the bus bar welding surface, burrs generated during insert molding are removed, and the flatness is improved. And according to the sealing body, when welding the bus bar to the bus bar welding surface, a gap is formed between the bus bar welding surface and the bus bar by arranging the bus bar to contact the end surface of the side wall portion, and the adhesion between the bus bar and the battery terminal can be prevented. Therefore, by using the sealing body, heat transfer from the bus bar to the battery terminal can be suppressed, and a secondary battery in which problems such as melting and heat sag of resin parts disposed around the battery terminal are suppressed can be realized. Furthermore, by using the sealing body, it is possible to realize a secondary battery in which the occurrence of welding defects due to burrs generated during insert molding and the low flatness during bus bar welding to the bus bar welding surface is suppressed.

[0012] A further characteristic configuration of the method for manufacturing a sealing body according to the present invention is that in the welding surface treatment step, the bus bar welding surface having an uneven shape is formed by the processing.

[0013] According to the above characteristic configuration, a sealing body with a large surface area of the bus bar welding surface can be manufactured. And according to the sealing body, the amount of heat radiated from the bus bar welding surface can be increased. Therefore, by using the sealing body, a secondary battery can be realized in which the amount of heat radiated from the bus bar welding surface is large, and problems such as melting of the resin member due to heat generated by energization and heat sagging are more suppressed.

[0014] A further characteristic configuration of the method for manufacturing a sealing body according to the present invention is that the processing in the welding surface treatment step is a processing by laser.

[0015] According to the above characteristic configuration, a sealing body in which at least the strength in the vicinity of the bus bar welding surface is improved by the quenching effect due to rapid heating and rapid cooling in the processing by laser can be manufactured. Therefore, by using the sealing body, a secondary battery with improved durability against external forces such as vibration can be realized.

[0016] A further characteristic configuration of the method for manufacturing a sealing body according to the present invention is that the processing in the welding surface treatment step is a processing by shot blasting.

[0017] According to the above characteristic configuration, a sealing body in which at least the strength in the vicinity of the bus bar welding surface is improved by the residual compressive stress generated in the processing by shot blasting can be manufactured. Therefore, by using the sealing body, a secondary battery with improved durability against external forces such as vibration can be realized.

[0018] A characteristic configuration of the sealing body according to the present invention for achieving the above object is that it is a sealing body for a sealed secondary battery attached to an opening of a housing, a lid body having an attachment port penetrating through the front and back, A battery terminal having a flat portion whose surface is a bus bar welding surface, and the battery terminal is attached to the attachment port of the lid body in a state where the bus bar welding surface is disposed on one side of the lid body, An insulating member made of resin having a side wall portion extending in a direction away from the lid body along the flat portion of the battery terminal, and insulating the lid body and the battery terminal, The insulating member is formed integrally with the lid body and the battery terminal so as to fill the space between the attachment port and the battery terminal by insert molding, and the end face on the downstream side in the extending direction of the side wall portion protrudes more than the bus bar welding surface.

[0019] According to the above characteristic configuration, when welding the bus bar to the bus bar welding surface, a gap is formed between the bus bar welding surface and the bus bar by arranging the bus bar to abut against the end face of the side wall portion, and the close contact between the bus bar and the battery terminal can be prevented. Therefore, by using the sealing body, heat transfer from the bus bar to the battery terminal can be suppressed, and a secondary battery in which the occurrence of defects in resin parts disposed around the battery terminal can be suppressed can be realized. Further, according to the above characteristic configuration, even if burrs are generated on the surface side of the flat portion during insert molding of the insulating member, the flat surface of the flat portion of the battery terminal is processed so that the end face of the side wall portion of the insulating member protrudes more than the bus bar welding surface, so that the burrs are removed and the flatness of the bus bar welding surface is improved. Therefore, by using the sealing body, a secondary battery in which the occurrence of welding defects during welding of the bus bar to the bus bar welding surface can be suppressed can be realized.

[0020] A further characteristic configuration of the sealing body according to the present invention is The bus bar welding surface has an uneven shape.

[0021] According to the above characteristic configuration, the surface area of the bus bar welding surface is large, and the amount of heat radiated from the bus bar welding surface increases. Therefore, by using the sealing body, a secondary battery in which the amount of heat radiated from the bus bar welding surface is large and the occurrence of defects in resin members due to heat generated by energization or the like is further suppressed can be realized.

Effects of the Invention

[0022] As described above, according to the method for manufacturing a sealing body and the sealing body according to the present invention, it is possible to suppress the occurrence of defects in the resin member around the battery terminal, and to realize a secondary battery in which the occurrence of welding defects during bus bar welding to the bus bar welding surface is suppressed.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0024] Hereinafter, a method for manufacturing a sealing body and the sealing body according to an embodiment of the present invention will be described with reference to the drawings. In the following, a lithium ion secondary battery including a sealing body will be described as an example. In addition, in the following, for the sake of clarity, each description and each drawing are appropriately simplified.

[0025] 〔Outline of Secondary Battery 1〕 FIG. 1 is an exploded perspective view of a secondary battery 1 including a sealing body 12 manufactured by the method for manufacturing a sealing body according to the present 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 vertical direction, the X-axis direction and the Y-axis direction are orthogonal to each other, and are parallel to the horizontal direction.

[0026] As shown in FIG. 1, the secondary battery 1 includes a battery case 10, metal battery terminals PS and NS, an electrode body 20, and the like. In the secondary battery 1, the battery case 10 is composed of a case body 11 having an opening and a sealing plate 13 that constitutes the sealing body 12. The electrode body 20 is housed inside the case body 11, the opening of the case body 11 is sealed with the sealing plate 13, and then an electrolytic solution is injected into the case body 11 to form a sealed secondary battery.

[0027] 〔Configuration of the battery case 10〕 As shown in FIG. 1, the battery case 10 of the present embodiment is composed of a substantially rectangular parallelepiped case body 11 with an open top and a sealing plate 13 that seals the opening of the case body 11. In the battery case 10 of the present embodiment, both the case body 11 and the sealing plate 13 are made of aluminum, but the present invention is not limited thereto. Various metals and alloys may be appropriately selected as the materials of the case body 11 and the sealing plate 13 according to the type and application of the battery. In the present embodiment, the case body 11 corresponds to the "housing", and the sealing plate 13 corresponds to the "lid body".

[0028] Details will be described later, but the sealing plate 13 of the present embodiment constitutes a part of the sealing body 12. In the present embodiment, the sealing plate 13 has a shape corresponding to the shape of the opening of the case body 11 and is configured to be able to seal the opening of the case body 11.

[0029] 〔Configuration of the electrode body 20〕 In this embodiment, the electrode body 20 is formed of a wound body obtained by winding a long strip-shaped positive electrode material and a negative electrode material with a strip-shaped separator interposed therebetween and compressing the wound body into a flat shape. As shown in FIG. 1, the electrode body 20 of this embodiment is substantially rectangular in a thickness direction view (Y-axis direction view), and a positive electrode terminal joint portion 21 where the positive electrode material is collected on one end side in the longitudinal direction (X-axis direction) in the thickness direction view, and a negative electrode terminal joint portion 22 where the negative electrode material is collected is formed on the other end side. Note that the structure of the electrode body 20 is not particularly limited, and various structures used in general sealed secondary batteries can be adopted. Also, the materials used for the positive electrode material and the negative electrode material 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.

[0030] The electrode body 20 is housed inside the case body 11 in a posture where the thickness direction and the longitudinal direction are parallel to the horizontal direction. The electrode body 20 and the case body 11 are insulated by an insulating film.

[0031] 〔Configuration of the sealing body 12〕 Next, with reference to FIGS. 1 to 4, the detailed configuration of the sealing body 12 will be described. FIG. 2 is a cross-sectional view showing the schematic configuration of the sealing body 12, FIG. 3 is a cross-sectional view of the III-III portion of FIG. 2, and FIG. 4 is a cross-sectional view of the IV-IV portion of FIG. 2.

[0032] As shown in FIGS. 1 to 4, the sealing body 12 includes a sealing plate 13, a positive electrode battery terminal PS, a negative electrode battery terminal NS, a positive electrode insulating member 35, and a negative electrode insulating member 40.

[0033] The sealing plate 13 is a plate-shaped member that seals the opening of the case body 11, and a positive electrode attachment port 14 and a negative electrode attachment port 15 penetrating through the front and back surfaces (upper and lower surfaces) are formed. Specifically, the sealing plate 13 of this embodiment is composed of a flat plate member that is substantially rectangular in a Z-axis direction view. The positive electrode attachment port 14 is formed on one end side in the longitudinal direction of the sealing plate 13, and the negative electrode attachment port 15 is formed on the other end side in the longitudinal direction. Note that the front surface of the sealing plate 13 is the surface facing the outside of the secondary battery 1, and the back surface is the surface facing the inside of the secondary battery 1.

[0034] As shown in FIGS. 1 and 2, the sealing body 12 of the present embodiment includes, as a positive electrode side configuration, a positive electrode battery terminal PS and a positive electrode insulating member 35 attached to a positive electrode attachment port 14 of a sealing plate 13, and includes, as a negative electrode side configuration, a negative electrode battery terminal NS and a negative electrode insulating member 40 attached to a negative electrode attachment port 15. The positive electrode battery terminal PS and the negative electrode battery terminal NS are attached so that respective bus bar welding surfaces Ba and Bb, which will be described later, are disposed on the surface side of the sealing plate 13 (in other words, the outer side of the secondary battery 1).

[0035] In the sealing body 12 of the present embodiment, the positive electrode side and the negative electrode side differ in that the positive electrode battery terminal PS is composed of one member, and the negative electrode battery terminal NS is composed of a dissimilar material joining member in which two members made of different metal materials are joined. However, except for configurations related to dissimilar material joining (such as caulking parts), the positive electrode battery terminal PS and the negative electrode battery terminal NS have substantially the same outer shape.

[0036] Hereinafter, the configuration of the negative electrode side will be described with reference to FIGS. 2 to 4. The negative electrode battery terminal NS is a dissimilar material joining member composed of a first terminal member 26 and a second terminal member 28. In the present embodiment, the first terminal member 26 is made of aluminum, and the second terminal member 28 is made of copper.

[0037] The first terminal member 26 has a plate-like portion 27 that is substantially rectangular in shape when viewed in the Z-axis direction. The surface of the plate-like portion 27 is a bus bar welding surface Bb to which a bus bar B made of aluminum is welded and connected. As shown in FIG. 4, in the present embodiment, the bus bar welding surface Bb has an uneven shape. Specifically, the bus bar welding surface Bb has an uneven shape formed by a laser processing treatment in the manufacturing process of the sealing body 12, which will be described later, and is a surface having a surface roughness (Ra) within a predetermined range. The surface roughness (Ra) is preferably 1 μm or more and 10 μm or less.

[0038] The second terminal member 28 has a plate-like portion 29 that is substantially rectangular in shape when viewed in the Z-axis direction, and a plate-like current collecting portion 30 that extends downward from the back surface of the plate-like portion 29. The current collecting portion 30 has an electrode connection portion 30a at its lower end, and the electrode connection portion 30a is joined to the negative electrode terminal joining portion 22 of the electrode body 20.

[0039] Although detailed description is omitted, the negative electrode battery terminal NS of this embodiment fixes the first terminal member 26 and the second terminal member 28 by caulking in a state where the plate-like portion 27 of the first terminal member 26 and the plate-like portion 29 of the second terminal member 28 are overlapped, and the interface between the first terminal member 26 and the second terminal member 28 in the caulked portion is joined by ultrasonic bonding. Thereby, conduction between the first terminal member 26 and the second terminal member 28 is ensured in the negative electrode battery terminal NS. In the following description, it is assumed that the portion where the plate-like portion 27 of the first terminal member 26 and the plate-like portion 29 of the second terminal member 28 are overlapped (portion A in FIGS. 3 and 4) is the flat portion 31 of the negative electrode battery terminal NS.

[0040] The negative electrode insulating member 40 is a member made of an insulating material. In this embodiment, the negative electrode insulating member 40 is a member made of PPS (polyphenylene sulfide) resin.

[0041] Although details will be described later, the negative electrode insulating member 40 is formed integrally with the sealing plate 13 and the negative electrode battery terminal NS so as to fill the space between the negative electrode mounting port 15 and the negative electrode battery terminal NS by insert molding. The sealing plate 13 and the negative electrode battery terminal NS are insulated by the negative electrode insulating member 40, and the negative electrode insulating member 40 maintains the airtightness between the negative electrode battery terminal NS and the negative electrode mounting port 15 of the sealing plate 13.

[0042] Specifically, the negative electrode insulating member 40 of this embodiment has a base portion 41 and a side wall portion 42 that is a frame-like portion having a rectangular shape in plan view, and the flat portion 31 of the negative electrode battery terminal NS is disposed within the frame.

[0043] In this embodiment, the base portion 41 is a portion located below the plane parallel to the horizontal direction including the back surface of the plate-like portion 29 of the second terminal member 28 at the negative electrode battery terminal NS. An engagement groove 41a is formed on the outer peripheral surface of the base portion 41, and the edge of the negative electrode attachment port 15 is engaged with the engagement groove 41a, thereby realizing insulation between the sealing plate 13 and the negative electrode battery terminal NS and maintaining airtightness between the negative electrode battery terminal NS and the negative electrode attachment port 15.

[0044] In this embodiment, the side wall portion 42 of the negative electrode insulating member 40 extends upward from the peripheral edge portion of the surface of the base portion 41 along the side surface of the flat portion 31 at the negative electrode battery terminal NS. In other words, the side wall portion 42 extends in a direction away from the sealing plate 13 along the side surface of the flat portion 31 at the negative electrode battery terminal NS. Further, the end surface (upper end surface) 42a on the downstream side in the extending direction (Z-axis direction) of the side wall portion 42 protrudes from the bus bar welding surface Bb. In this embodiment, the side wall portion 42 of the negative electrode insulating member 40 protrudes from the bus bar welding surface Bb such that a gap S having a predetermined dimension is formed between the plane parallel to the bus bar welding surface Bb and including the upper end surface 42a and the bus bar welding surface Bb (see FIG. 4). Note that the gap S between the plane including the upper end surface 42a and the bus bar welding surface Bb is the gap between the plane including the highest portion of the bus bar welding surface Bb and the plane including the upper end surface 42a of the side wall portion 42, as shown in FIG. 4.

[0045] The protruding amount of the upper end surface 42a of the side wall portion 42 is not particularly limited. However, when welding the bus bar B to the bus bar welding surface Bb, which will be described later, if the protruding amount is too large, the gap S will become too large, which may hinder the welding between the bus bar B and the bus bar welding surface Bb. Conversely, if the protruding amount is too small, the gap S will become too small, and the contact area between the back surface of the bus bar B and the bus bar welding surface Bb is likely to increase. Therefore, the protruding amount is preferably a value such that the dimension of the gap S is 0.002 mm or more and 0.2 mm or less, for example. In this embodiment, the upper end surface 42a of the side wall portion 42 protrudes from the bus bar welding surface Bb such that the dimension of the gap S is approximately 0.1 mm.

[0046] In this embodiment, the positive electrode battery terminal PS has substantially the same outer shape as the negative electrode battery terminal NS and is composed of a single member. In this embodiment, the positive electrode battery terminal PS is made of aluminum.

[0047] Although details are omitted, on the positive electrode side of this embodiment, the positive electrode battery terminal PS includes a current collecting portion 24 having a flat portion 23 whose surface is the bus bar welding surface Ba and an electrode connection portion 24a to which the positive electrode terminal joint portion 21 is joined. The bus bar welding surface Ba of the positive electrode battery terminal PS has an uneven shape formed by laser processing during the manufacturing process of the sealing body 12, and like the bus bar welding surface Bb of the negative electrode battery terminal NS, it is a surface having a surface roughness (Ra) within a predetermined range.

[0048] Also, the positive electrode insulating member 35 has the same configuration as the negative electrode insulating member 40. That is, it is formed integrally with the sealing plate 13 and the positive electrode battery terminal PS by insert molding, and the upper end surface 36a of the side wall portion 36 protrudes more than the bus bar welding surface Ba. The protruding amount of the upper end surface 36a of the side wall portion 36 may be a value such that the gap S has a predetermined dimension, similar to the negative electrode insulating member 40. In this embodiment, the upper end surface 36a protrudes more than the bus bar welding surface Ba so that the dimension of the gap S is approximately 0.1 mm.

[0049] 〔Manufacturing method of the sealing body 12〕 Next, the manufacturing method of the sealing body 12 according to this embodiment will be described. The method for manufacturing the sealing body 12 includes an insert molding step and a welding surface treatment step.

[0050] Hereinafter, taking the negative electrode side as an example, it will be described with reference to FIGS. 5 to 7. FIGS. 5 to 7 are schematic diagrams for explaining the manufacturing process of the sealing body 12. Specifically, FIG. 5 is a schematic diagram showing a state in which the negative electrode battery terminal NS and the sealing plate 13 are arranged in the cavity C of the mold M in the insert molding step. FIG. 6 is a schematic diagram showing a state in which molten resin is injected into the cavity C of the mold M in the insert molding step. Further, FIG. 7 is a schematic diagram showing the welding surface treatment step.

[0051] The insert molding process is a process in which the sealing plate 13 is placed in the mold M, the negative electrode battery terminal NS is positioned in the negative electrode attachment port 15 of the sealing plate 13, and in a state where the surface side of the flat portion 31 is in contact with the inner surface of the mold M, the mold M is filled with resin, and the negative electrode insulating member 40 is molded in an integrated state with the sealing plate 13 and the negative electrode battery terminal NS so as to fill the space between the negative electrode attachment port 15 and the negative electrode battery terminal NS. Note that, among the surfaces of the negative electrode battery terminal NS, the portion that comes into contact with the negative electrode insulating member 40 to form a seal portion is subjected to a roughening treatment prior to the insert molding process. The roughening treatment can be performed using, for example, a laser.

[0052] Specifically, in the present embodiment, as shown in FIGS. 5 and 6, resin molding of the negative electrode insulating member 40 is performed using a mold M composed of an upper mold M1 and a lower mold M2. First, as shown in FIG. 5, the sealing plate 13 and the negative electrode battery terminal NS are placed in a cavity C partitioned by the upper mold M1 and the lower mold M2. At this time, the surface side of the flat portion 31 (more specifically, the plate-like portion 27 of the first terminal member 26) is brought into contact with the upper inner surface of the upper mold M1.

[0053] Next, as shown in FIG. 6, the molten resin (PPS resin in the present embodiment) is injected from a nozzle into the cavity C through a gate G formed in the upper mold M1. Then, the injected molten resin fills the cavity C, and the negative electrode insulating member 40 is formed in an integrated state with the sealing plate 13 and the negative electrode battery terminal NS so as to fill the space between the negative electrode attachment port 15 and the negative electrode battery terminal NS. Note that, for the positive electrode side as well, by going through the insert molding process, a positive electrode insulating member 35 in an integrated state with the sealing plate 13 and the positive electrode battery terminal PS is formed.

[0054] Here, there is inevitably a gap between the peripheral edge portion of the surface of the flat portion 31 and the upper inner surface of the upper mold M1. Therefore, the molten resin creeps into the gap, and as shown in FIG. 6, a burr D is generated on the surface of the flat portion 31 of the negative electrode battery terminal NS. And if this generated burr D is left without being removed, welding defects are likely to occur when welding the bus bar B to the surface of the flat portion 31 which is the bus bar welding surface.

[0055] The welding surface treatment step is a step of performing a machining process on the surface side of the flat portion 31 of the negative electrode battery terminal NS so that the end surface (upper end surface 42a) on the downstream side in the extending direction (Z-axis direction) of the side wall portion 42 of the negative electrode insulating member 40 protrudes more than the bus bar welding surface Bb after the insert molding step.

[0056] Specifically, as shown in FIG. 7, in the present embodiment, after the insert molding step, a laser machining process is performed on the entire surface side of the flat portion 31 (plate-like portion 27 of the first terminal member 26) (in other words, the entire portion overlapping the flat portion 31 when viewed in the Z-axis direction), so that the upper end surface 42a of the side wall portion 42 of the negative electrode insulating member 40 protrudes more than the bus bar welding surface Bb, and the distortion and deflection of the bus bar welding surface Bb are removed to improve the flatness of the bus bar welding surface Bb. Further, by performing the laser machining process, an uneven shape is formed on the bus bar welding surface Bb. Note that the laser machining process is preferably performed under appropriate processing conditions in consideration of the material of the negative electrode battery terminal NS so that the surface roughness (Ra) is within a predetermined range (for example, the surface roughness (Ra) is 1 μm or more and 10 μm or less).

[0057] Here, as described above, when the negative electrode insulating member 40 is insert molded, burrs D are generated on the surface of the flat portion 31 of the negative electrode battery terminal NS. However, in the manufacturing method according to the present embodiment, the burrs D are removed by performing a laser machining process on the surface side of the flat portion 31 (see also FIGS. 3 and 4).

[0058] That is, according to the manufacturing method of the present embodiment, it is possible to simultaneously perform processing to make the upper end surface 42a of the side wall portion 42 of the negative electrode insulating member 40 protrude from the bus bar welding surface Bb, and removal of burrs D generated when the negative electrode insulating member 40 is formed by insert molding. Also, the flatness of the bus bar welding surface Bb can be improved. In the present application, "the flatness is improved" means that distortions and deflections generated in the molding process of the terminal are removed, and it does not necessarily mean that the surface roughness (Ra) is smoothed to be within a predetermined range. That is, "the flatness is improved" includes a state where the surface roughness (Ra) is not within a predetermined range.

[0059] Regarding the positive electrode side as well, by performing a welding surface treatment step after the insert molding step, the upper end surface 36a of the side wall portion 36 of the positive electrode insulating member 35 protrudes from the bus bar welding surface Ba, the flatness is improved, and a bus bar welding surface Ba having an uneven shape is formed.

[0060] As described above, according to the manufacturing method of the sealing body 12 of the present embodiment, the upper end surfaces 36a, 42a of the side wall portions 36, 42 of the respective insulating members 35, 40 protrude from the bus bar welding surfaces Ba, Bb, the burrs D generated during insert molding are removed, and the sealing body 12 having bus bar welding surfaces Ba, Bb with improved flatness can be preferably manufactured. Also, according to the manufacturing method of the sealing body 12 of the present embodiment, the sealing body 12 provided with bus bar welding surfaces Ba, Bb having an uneven shape formed by laser processing can be preferably manufactured.

[0061] FIG. 8 is a diagram showing a state where a bus bar B is welded to a bus bar welding surface Bb of a negative electrode battery terminal NS. In FIG. 8, reference sign W denotes a welded bead portion. According to the sealing body 12 manufactured by the manufacturing method according to the present embodiment, as shown in FIG. 8, when welding the bus bar B to the bus bar welding surface Bb, by arranging the bus bar B to abut against the upper end surface 42a (end surface) of the side wall portion 42, a gap S is formed between the bus bar welding surface Bb and the bus bar B, and adhesion between the bus bar B and the negative electrode battery terminal NS can be prevented. Therefore, in the secondary battery 1 including the sealing body 12, heat transfer from the bus bar B to the negative electrode battery terminal NS is suppressed, and defects such as melting and heat sagging of resin components (specifically, the negative electrode insulating member 40) disposed around the negative electrode battery terminal NS are less likely to occur. Although illustration is omitted, similarly on the positive electrode side, defects in resin components disposed around the positive electrode battery terminal PS are less likely to occur.

[0062] Further, the burr D generated during insert molding is removed from the sealing body 12, and the flatness of the bus bar welding surfaces Ba and Bb is also improved. Therefore, in the secondary battery 1 including the sealing body 12, the occurrence of welding defects during bus bar welding to the bus bar welding surfaces Ba and Bb is suppressed.

[0063] Furthermore, the bus bar welding surfaces Ba and Bb of the sealing body 12 have an uneven shape. Therefore, the sealing body 12 has a larger surface area of the bus bar welding surfaces Ba and Bb and a larger amount of heat dissipation from the bus bar welding surfaces Ba and Bb compared to those having no uneven shape. Therefore, in the secondary battery 1 including the sealing body 12, defects such as melting and heat sagging of the resin member due to heat generated by energization are less likely to occur.

[0064] In addition, since the bus bar welding surfaces Ba and Bb of the sealing body 12 are subjected to laser processing, the strength of at least the portion located near the bus bar welding surface among the battery terminals PS and NS is improved by the quenching effect due to rapid heating and cooling in the laser processing. Therefore, the secondary battery 1 including the sealing body 12 has high durability against external forces such as vibration.

[0065] 〔Alternative Embodiment〕 〔1〕In the above embodiment, the mode of performing laser processing in the weld surface processing step has been described, but it is not limited to such a mode. For example, a mode of performing shot blasting processing or cutting processing using a tool instead of laser processing may be adopted, or a mode of combining a plurality of these may be adopted. Even in this case, the bus bar weld surfaces Ba and Bb having an uneven shape can be formed. Even in this case, it is preferable to perform the processing under appropriate conditions in consideration of the materials of the respective battery terminals PS and NS so that the surface roughness (Ra) is within a predetermined range (for example, the surface roughness (Ra) is 1 μm or more and 10 μm or less). When shot blasting processing is adopted, in the sealed body 12 to be manufactured, the strength of at least the portion located near the bus bar weld surface among the respective battery terminals PS and NS is improved by the residual compressive stress generated by the shot blasting processing. Therefore, when shot blasting processing is adopted, the secondary battery 1 provided with the sealed body 12 has high durability against external forces such as vibration.

[0066] 〔2〕In the above embodiment, the mode of forming the bus bar weld surface having an uneven shape by processing in the weld surface processing step has been described, but it is not limited to such a mode. In the weld surface processing step, a mode of forming a bus bar weld surface having no uneven shape may be adopted. The processing in the weld surface processing step can make the upper end surfaces 36a and 42a of the side wall portions 36 and 42 in the respective insulating members 35 and 40 protrude from the bus bar weld surfaces Ba and Bb, and any processing may be used as long as it can remove the distortion and deflection of the bus bar weld surfaces Ba and Bb and improve the flatness of the bus bar weld surfaces Ba and Bb. After performing processing such that the bus bar weld surfaces Ba and Bb do not have an uneven shape, a mode of forming an uneven shape on the bus bar weld surfaces Ba and Bb by the above-described laser processing, shot blasting processing, cutting processing using a tool, or the like may be adopted.

[0067] 〔3〕In the above-described embodiment, the positive electrode battery terminal PS is composed of one member, and the negative electrode battery terminal NS is composed of a dissimilar material joining member in which two members made of different metal materials are joined. However, the present invention is not limited to such an embodiment. The positive electrode battery terminal PS and the negative electrode battery terminal NS may both be composed of two members, or both may be composed of one member.

[0068] Note that the configurations disclosed in the above-described embodiment (including other embodiments, the same applies hereinafter) can be applied in combination with the configurations disclosed in other embodiments as long as there is no contradiction. Also, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope not departing from the object of the present invention.

Explanation of Reference Numerals

[0069] 1: Secondary battery 11: Case body (housing) 12: Sealing body 13: Sealing plate (lid) 14: Positive electrode attachment port (attachment port) 15: Negative electrode attachment port (attachment port) 23, 31: Flat portion 35: Positive electrode insulating member (insulating member) 36: Side wall portion 36a: Upper end surface (end surface on the downstream side in the extending direction) 40: Negative electrode insulating member (insulating member) 42: Side wall portion 42a: Upper end surface (end surface on the downstream side in the extending direction) PS: Positive electrode battery terminal (battery terminal) NS: Negative electrode battery terminal (battery terminal) B: Bus bar Ba, Bb: Bus bar welding surface M: Mold

Claims

1. A lid body having a mounting hole penetrating through from front to back, A battery terminal having a flat portion whose surface is a bus bar welding surface, and being attached to the mounting hole of the lid body such that the bus bar welding surface is disposed on one side surface of the lid body, An insulating member made of resin, having a side wall portion extending in a direction away from the lid body along the flat portion of the battery terminal, and insulating the lid body and the battery terminal, and a method for manufacturing a sealing body for a sealed secondary battery, comprising: An insert molding step of disposing the lid body in a mold, disposing the battery terminal in the mold such that the battery terminal is located in the mounting hole of the lid body and the surface side of the flat portion abuts against the inner surface of the mold, filling the mold with resin, and molding in a state integrated with the lid body and the battery terminal so as to fill the space between the mounting hole and the battery terminal with the insulating member; A welding surface treatment step of performing a processing treatment on the surface side of the flat portion of the battery terminal such that, after the insert molding step, an end surface on the downstream side in the extending direction of the side wall portion of the insulating member protrudes more than the bus bar welding surface, the method for manufacturing a sealing body.

2. In the welding surface treatment step, the bus bar welding surface having an uneven shape is formed by the processing treatment, the method for manufacturing a sealing body according to claim 1.

3. The processing treatment in the welding surface treatment step is a processing treatment by laser, the method for manufacturing a sealing body according to claim 2.

4. The processing treatment in the welding surface treatment step is a processing treatment by shot blasting, the method for manufacturing a sealing body according to claim 2.

5. A sealing body for a sealed secondary battery attached to an opening of a housing, comprising: A lid body having a mounting hole penetrating through from front to back, A battery terminal having a flat portion whose surface is a bus bar welding surface, and being attached to the mounting hole of the lid body in a state where the bus bar welding surface is disposed on one side surface of the lid body, It includes an insulating member made of resin, which has a side wall portion extending in a direction away from the lid along the flat portion of the battery terminal, and insulates the lid from the battery terminal. The insulating member is formed integrally with the lid and the battery terminal so as to fill the space between the mounting port and the battery terminal by insert molding, and a sealing body in which the end face on the downstream side in the extending direction of the side wall portion protrudes more than the bus bar welding surface.

6. The bus bar welding surface has an uneven shape. The sealing body according to claim 5.

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