Secondary battery

Abstract

To provide a secondary battery which suppresses reduction or impact resistance or airtightness caused by refusion of an insulation member in laser welding between a sealing body and a housing and in which a battery terminal is hard to fall from a lid body.SOLUTION: A sealing body comprises a lid body 13, a battery terminal NS and an insulation member 45. The lid body 13 includes: a return part 16 extending from at least a portion of an opening edge of a mounting port 15 toward the side of the rear face 13b of the lid body 13; and a rough part 17 which is formed in the opening edge of the mounting port 15 and the return part 16 and consists of fine projections 17a. The insulation member 45 is formed while covering the rough part 17, which is formed in the mounting port 15 and the return part 16, and integrated with the lid body 13 and the battery terminal NS so as to fill a gap between the mounting port 15 and the battery terminal NS. In a state where a boundary portion between an opening edge of a housing 11 and the peripheral edge of the lid body 13 is laser-welded, the opening of the housing 11 is sealed by the sealing body.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a secondary battery.

Background Art

[0002] Conventionally, secondary batteries such as lithium-ion storage batteries have been used as power sources for electric vehicles and hybrid vehicles. This type of secondary battery includes, for example, a battery case composed of a lid body and a case body, an electrode body housed inside the battery case, and battery terminals connected to the electrode body for taking out electricity to the outside. In such a secondary battery, generally, the battery terminals are assembled to the lid body, and the space between the battery terminals and the lid body is insulated by an insulating member. Then, the lid body with the battery terminals assembled is laser-welded to the case body, and the opening of the case body is sealed by the lid body.

[0003] Here, various methods have been proposed for assembling the battery terminals to the lid body. For example, the method disclosed in Patent Document 1 has been proposed.

[0004] In the method described in Patent Document 1, an electrode is assembled to the battery lid by integrally molding a holder resin for insulating between the battery lid and the electrode by insert molding. Further, in the method described in Patent Document 1, fine groove portions are formed in advance at locations (such as around the through holes of the battery lid) that will come into contact with the holder resin on the battery lid and the electrode, so that the resin enters these groove portions during insert molding, and the battery lid, the electrode, and the holder resin are brought into close contact to ensure airtightness.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Here, a secondary battery including a battery case lid manufactured by the method described in Patent Document 1 has the following problems.

[0007] That is, in order to seal the opening of the case body with the battery case lid, when the boundary portion between the peripheral edge of the lid body constituting the battery case lid and the opening edge of the case body is laser welded, the temperature of the lid body rises due to the heat generated by the laser welding. As a result, re-melting of the holder resin occurs around the through hole in the lid body, and air bubbles are generated in the holder resin. Therefore, the strength of the holder resin decreases, the impact resistance of the secondary battery decreases, or the airtightness of the secondary battery decreases due to the presence of air bubbles between the holder resin and the lid body. In particular, since fine groove portions are formed around the through holes in the battery case lid, the contact area with the holder resin increases compared to the case where such groove portions are not formed, and re-melting of the holder resin due to the temperature rise of the lid body is likely to occur.

[0008] Further, in the secondary battery including the above battery case lid, for example, when a bus bar is connected to an electrode and a load is applied from the bus bar, the holder resin or the electrode integrated therewith may fall off from the lid body.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a secondary battery in which a decrease in impact resistance and airtightness due to re-melting of an insulating member during laser welding of a sealing body and a housing is suppressed, and a battery terminal is less likely to fall off from a lid body.

Means for Solving the Problems

[0010] A characteristic configuration of a secondary battery according to the present invention for achieving the above object is a secondary battery including a housing having an opening and a sealing body for sealing the opening of the housing, wherein the sealing body includes a lid body having a mounting hole penetrating through the front and back, A battery terminal having a bus bar connection surface and attached to the mounting opening of the lid body such that the bus bar connection surface is disposed on the side of the surface of the lid body, and a resin insulating member that insulates the lid body and the battery terminal, wherein the lid body, has a return portion extending from at least a part of the opening edge of the mounting opening toward the back surface side of the lid body, and a roughened portion formed of minute protrusions and formed on the opening edge of the mounting opening and the return portion, the insulating member covers the roughened portion formed on the mounting opening and the return portion, and is formed integrally with the lid body and the battery terminal so as to fill the space between the mounting opening and the battery terminal, the opening of the housing is sealed with the sealing member in a state where the boundary portion between the opening edge of the housing and the peripheral edge of the lid body is laser welded.

[0011] According to the above characteristic configuration, the return portion extends from the opening edge of the mounting opening, and the return portion is farther from the laser welding location when sealing the opening of the housing with the sealing member than the opening edge of the mounting opening. Therefore, the temperature rise due to the heat generated by laser welding is suppressed at the tip of the return portion, and the resin melting of the insulating member is suppressed as it approaches the tip of the return portion. Thus, the generation of bubbles due to the remelting of the insulating member is suppressed closer to the tip of the return portion. Therefore, a decrease in impact resistance and sealing performance is suppressed as compared with the case where the return portion is not provided. In addition, since the return portion extends toward the back surface side of the lid body, when a load is applied to the bus bar connected to the bus bar connection surface, the insulating member and the battery terminal integrated therewith are less likely to fall off from the lid body.

[0012] A further characteristic configuration of the secondary battery according to the present invention is, that the angle formed by the direction orthogonal to the opening surface of the mounting opening and the extending direction of the return portion is 0° or more and 45° or less.

[0013] According to the above-described characteristic configuration, while ensuring the distance between the return portion and the laser welding location, it becomes more difficult for the insulating member and the battery terminal to fall off from the lid due to impact.

[0014] A further characteristic configuration of the secondary battery according to the present invention is that the return portion extends from the entire circumference of the opening edge of the mounting opening.

[0015] According to the above-described characteristic configuration, since the return portion located at a position farther from the laser welding location than the opening edge of the mounting opening is formed on the entire circumference of the opening edge, a decrease in impact resistance and sealing performance can be further suppressed. Also, according to the above-described characteristic configuration, it becomes more difficult for the insulating member and the battery terminal to fall off from the lid due to impact.

Effects of the Invention

[0016] As described above, according to the secondary battery of the present invention, while suppressing a decrease in impact resistance and sealing performance caused by re-melting of the insulating member during laser welding of the sealing body and the housing, it becomes difficult for the battery terminal to fall off from the lid.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0018] Hereinafter, a secondary battery according to an embodiment of the present invention will be described with reference to the drawings. In the following, a mode in which the secondary battery is a lithium-ion secondary battery will be described as an example. Further, in the following, for the sake of clarity, each description and each drawing are appropriately simplified.

[0019] 〔Outline of Secondary Battery 1〕 FIG. 1 is a perspective view showing a schematic configuration of the secondary battery 1. FIG. 2 is a cross-sectional view showing a schematic configuration of the secondary battery. 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.

[0020] As shown in FIGS. 1 and 2, the secondary battery 1 includes a battery case 10, metal battery terminals PS and NS, an electrode body 20, etc. In the secondary battery 1, the battery case 10 is composed of a case body 11 having an opening and a sealing plate 13 constituting a sealing body 12. The electrode body 20 is accommodated inside the case body 11, the opening of the case body 11 is sealed with the sealing plate 13 by laser welding, and then an electrolytic solution is injected into the case body 11, which is a sealed secondary battery.

[0021] 〔Configuration of Battery Case 10〕 As shown in FIGS. 1 and 2, the battery case 10 of the present embodiment is composed of a case body 11 having a substantially rectangular parallelepiped shape with an open top and a sealing plate 13 for sealing 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 it is not limited thereto. For the materials of the case body 11 and the sealing plate 13, various metals and alloys may be appropriately selected according to the type and use 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".

[0022] The sealing plate 13 of this embodiment forms a part of the sealing body 12. In this 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. Although details will be described later, in the secondary battery 1 of this embodiment, the boundary portion between the peripheral edge of the sealing plate 13 and the opening edge of the case body 11 is laser welded, and the opening of the case body 11 is sealed by the sealing body 12.

[0023] 〔Configuration of the electrode body 20〕 In this embodiment, the electrode body 20 is configured as a wound body that is wound in a state where a long strip-shaped positive electrode material and negative electrode material are laminated via a strip-shaped separator and compressed 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 by a current collector foil is formed 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 by a current collector foil 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.

[0024] 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.

[0025] 〔Configuration of the sealing body 12〕 Next, with reference to FIGS. 1 to 5, the detailed configuration of the sealing body 12 will be described. FIG. 3 is a top view of the sealing plate 13, FIG. 4 is a cross-sectional view of the IV-IV portion of FIG. 1, and FIG. 5 is a cross-sectional view of the V-V portion of FIG. 4.

[0026] As shown in FIGS. 1 and 2, 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 40, and a negative electrode insulating member 45.

[0027] As shown in FIGS. 1 to 3, the sealing plate 13 is a plate-like 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 the present embodiment is composed of a flat plate member having a substantially rectangular shape when viewed in the Z-axis direction, and a positive electrode attachment port 14 and a negative electrode attachment port 15 having a substantially rectangular shape when viewed in the Z-axis direction are formed. The positive electrode attachment port 14 is formed at one end side in the longitudinal direction of the sealing plate 13, and the negative electrode attachment port 15 is formed at the other end side in the longitudinal direction. Note that the surface 13a of the sealing plate 13 is the surface facing the outside of the secondary battery 1, and the back surface 13b is the surface facing the inside of the secondary battery 1 (in other words, the inside of the case body 11).

[0028] Also, as shown in FIGS. 2 to 5, the sealing plate 13 has a return portion 16 extending from the entire circumference of the opening edge of each attachment port 14, 15 toward the back surface 13b side of the sealing plate 13. Specifically, the return portion 16 of the present embodiment is a plate-like portion formed so as to extend obliquely downward from the entire circumference of the opening edge of each attachment port 14, 15 toward the inside of each attachment port 14, 15 when viewed in the Y-axis direction, such that the tip is located below the opening surface of each attachment port 14, 15. Note that the return portion 16 may be formed by bending a portion of the flat plate member constituting the sealing plate 13 that is located inside each attachment port 14, 15 rather than the opening edge of each attachment port 14, 15, or may be formed by welding a plate material to the opening edge of each attachment port 14, 15.

[0029] Further, in the present embodiment, the return portion 16 is formed such that the angle θ formed by the direction (Z-axis direction) orthogonal to the opening surface of each attachment port 14, 15 and the extending direction D is 0° or more and 45° or less. Note that in the present embodiment, the extending direction D is a direction parallel to the direction from the boundary P1 between the back surface 13b of the sealing plate 13 and the surface 16a (outer surface 16a) facing the outside of each attachment port 14, 15 in the return portion 16 to the tip P2 of the outer surface 16a of the return portion 16.

[0030] Further, on the outer surface of the sealing plate 13, a roughened portion 17 composed of minute protrusions 17a is formed in a region R1 (contact region R1) that comes into contact with each of the insulating members 40 and 45. That is, in the present embodiment, the roughened portion 17 is formed on the entire circumference of the opening edge portion of each of the attachment ports 14 and 15 and on the outer surface of the return portion 16 of the sealing plate 13. The roughened portion 17 is formed, for example, by performing a roughening process using a laser on a region to be roughened, that is, the contact region R1.

[0031] 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 40 attached to the positive electrode attachment port 14 of the sealing plate 13, and includes, as a negative electrode side configuration, a negative electrode battery terminal NS and a negative electrode insulating member 45 attached to the negative electrode attachment port 15. The positive electrode battery terminal PS and the negative electrode battery terminal NS are attached such that respective bus bar connection surfaces Ba and Bb, which will be described later, are disposed on the side of the surface 13a of the sealing plate 13 (in other words, the outer side of the secondary battery 1).

[0032] In the sealing body 12 of the present embodiment, on the positive electrode side and the negative electrode side, 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. Although they differ in terms of the presence or absence of a configuration related to dissimilar material joining (such as a caulked portion), both have substantially the same configuration. Therefore, hereinafter, the negative electrode side will be described as an example.

[0033] First, the configuration of the negative electrode battery terminal NS will be described with reference to FIGS. 4 and 5. The negative electrode battery terminal NS is a dissimilar material joining member composed of a first terminal member 30 and a second terminal member 35. In the present embodiment, the first terminal member 30 is made of aluminum and the second terminal member 35 is made of copper.

[0034] The first terminal member 30 has a plate-like portion 31 that is substantially rectangular in shape when viewed in the Z-axis direction. The surface of the plate-like portion 31 is a bus bar connection surface Bb to which the bus bar is welded and connected. Note that the connection mode between the bus bar connection surface Bb and the bus bar is not limited to a welding mode.

[0035] The second terminal member 35 has a plate-like portion 36 that is substantially rectangular in shape when viewed in the Z-axis direction, a plate-like current collecting portion 37 that extends downward from the back surface of the plate-like portion 36, and the like. Further, the current collecting portion 37 has an electrode connection portion 37a at its lower end, and the electrode connection portion 37a is joined to the negative electrode terminal joining portion 22 of the electrode body 20.

[0036] Although detailed description is omitted, the negative electrode battery terminal NS of the present embodiment fixes the first terminal member 30 and the second terminal member 35 by caulking in a state where the plate-like portion 31 of the first terminal member 30 and the plate-like portion 36 of the second terminal member 35 are overlapped, and the interface between the first terminal member 30 and the second terminal member 35 in the caulked portion is joined by ultrasonic bonding. Thereby, conduction between the first terminal member 30 and the second terminal member 35 is ensured in the negative electrode battery terminal NS.

[0037] The negative electrode insulating member 45 is a member made of an insulating material. In the present embodiment, the negative electrode insulating member 45 is a member made of PPS (polyphenylene sulfide) resin.

[0038] Note that the negative electrode insulating member 45 of the present embodiment 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 attachment port 15 and the negative electrode battery terminal NS by insert molding.

[0039] Further, the negative electrode battery terminal NS has an engagement groove 46 formed on its side surface, and the edge portion and the return portion 16 of the negative electrode attachment port 15 are engaged with the engagement groove 46, thereby realizing insulation between the sealing plate 13 and the negative electrode battery terminal NS and airtightness maintenance between the negative electrode battery terminal NS and the negative electrode attachment port 15.

[0040] Note that, as described above, a roughened portion 17 composed of minute protrusions 17a is formed in a region R1 (contact region R1) that contacts the negative electrode insulating member 45 on the outer surface of the sealing plate 13. Therefore, when resin penetrates between the minute protrusions during insert molding, the negative electrode insulating member 45 is firmly joined by an anchor effect on the contact surface with the sealing plate 13.

[0041] As described above, since the positive electrode side has the same configuration as the negative electrode side except for the configuration of the battery terminal and related configurations (such as the caulked portion), detailed description thereof will be omitted. In each figure, the bus bar connection surface of the positive electrode battery terminal PS is labeled with Ba, the current collecting portion is labeled with 26, and the electrode connection portion is labeled with 26a. Further, the engaging groove of the positive electrode insulating member 40 is labeled with 41.

[0042] As described above, in the secondary battery 1 of the present embodiment, the sealing plate 13 is laser welded to the case body 11, and the opening of the case body 11 is sealed by the sealing body 12.

[0043] Here, when the return portions 16 extending from the opening edge portions of the mounting ports 14 and 15 are not formed on the sealing plate 13, the following problems occur during the laser welding of the sealing plate 13 and the case body 11. FIG. 6 is a schematic diagram for explaining the problems that occur when the return portions 16 are not formed.

[0044] That is, as shown in FIG. 6, when laser welding the boundary portion between the peripheral edge of the sealing plate 13 and the opening edge of the case body 11, the heat generated by the laser welding is transmitted through the sealing plate 13, and the contact region R1 on the outer surface of the sealing plate 13 becomes high temperature. And in the secondary battery 1 of the present embodiment, since the roughened portion 17 composed of the minute protrusions 17a is formed in the contact region R1, the contact area between the sealing plate 13 and the negative electrode insulating member 45 is large, and heat is easily transmitted from the sealing plate 13 to the negative electrode insulating member 45. Therefore, near the contact region R1, remelting of the negative electrode insulating member 45 occurs, and bubbles K are generated in the negative electrode insulating member 45. As a result, the strength of the negative electrode insulating member 45 decreases, and the sealing property between the sealing plate 13 and the negative electrode insulating member 45 decreases due to the presence of the bubbles K between them. That is, the impact resistance and sealing property of the secondary battery 1 decrease. Note that the same problem occurs on the positive electrode side as well.

[0045] In contrast, in the secondary battery 1 according to the present embodiment, since the return portion 16 is formed on the sealing plate 13, the above problems are less likely to occur. FIG. 7 is a schematic diagram for explaining the effect when the return portion 16 is formed. In the following, the negative electrode side will be described as an example, but the same applies to the positive electrode side.

[0046] That is, in the secondary battery 1 of the present embodiment, as shown in FIG. 7, the return portion 16 is formed so as to extend from the opening edge portion of the negative electrode attachment port 15, and the distance from the laser welding portion increases toward the tip of the return portion 16. Therefore, the temperature of the return portion 16 is less likely to increase toward the tip. Therefore, even in the vicinity of the contact region R1, remelting of the negative electrode insulating member 45 is less likely to occur toward the tip of the return portion 16, and bubbles K are less likely to be generated in the negative electrode insulating member 45. Therefore, in the secondary battery 1 of the present embodiment, a decrease in impact resistance and sealing performance can be suppressed as compared with the case where the return portion 16 is not formed.

[0047] Also, as described above, in the secondary battery 1 of the present embodiment, since remelting of the negative electrode insulating member 45 is less likely to occur than in the case where the return portion is not formed, while suppressing remelting of the negative electrode insulating member 45, the output of the laser welding during sealing can be increased and the processing time can be reduced. In addition, since there is less need to change the welding conditions in consideration of remelting of the negative electrode insulating member 45, the robustness is improved, and the defective rate can be reduced. Furthermore, since the amount of resin filled in the cavity during insert molding of the negative electrode insulating member 45 is reduced, the processing time required for insert molding can be reduced. That is, according to the secondary battery 1 of the present embodiment, it is possible to realize a reduction in processing time due to an increase in the output of laser welding during sealing, a reduction in defective rate due to an improvement in the robustness of laser welding, and a reduction in cost due to a reduction in processing time during insert molding.

[0048] Also, when the return portion 16 is not formed on the sealing plate 13, for example, when a bus bar is connected to the bus bar connection surface Bb, if a load is applied from the bus bar to the negative electrode battery terminal NS due to an external disturbance or the like, the negative electrode battery terminal NS may drop off from the sealing plate 13 together with the negative electrode insulating member 45.

[0049] In contrast, in the secondary battery 1 of the present embodiment, the return portion 16 extends toward the back surface 13b side of the sealing plate 13, and the extending direction D of the return portion 16 is inclined by an angle θ with respect to the direction orthogonal to the opening surface of the negative electrode attachment port 15. Thus, when a vertical (Z-axis direction) load is applied from the bus bar to the negative electrode battery terminal NS, since the negative electrode insulating member 45 is caught by the return portion 16 of the sealing plate 13, the negative electrode insulating member 45 is less likely to fall off from the sealing plate 13, and the negative electrode battery terminal NS integrated with the negative electrode insulating member 45 is less likely to fall off.

[0050] In particular, in the secondary battery 1 of the present embodiment, since the angle θ is 0° or more and 45° or less, when a load (F in FIG. 7) from the bus bar occurs, Fcosθ ≧ Fsinθ, so that the negative electrode insulating member 45 and the negative electrode battery terminal NS integrated therewith are less likely to fall off from the sealing plate 13.

[0051] 〔Alternative Embodiment〕 〔1〕In the above embodiment, the aspect in which the angle θ formed between the direction orthogonal to the opening surface of each attachment port 14, 15 and the extending direction D of the return portion 16 is 0° or more and 45° or less has been described. However, it is not limited to such an aspect. As long as the return portion 16 extends toward the back surface 13b side of the sealing plate 13, it may extend toward either the inside or the outside of each of the attachment ports 14, 15. For example, the angle θ may be -45° or more and 45° or less.

[0052] 〔2〕In the above embodiment, the aspect in which the return portion 16 extends from the entire circumference of the opening edge portion of each attachment port 14, 15 has been described. However, it is not limited to such an aspect. As long as the return portion extends from at least a part of the opening edge portion of each attachment port 14, 15, compared with the case where the return portion is not formed, the generation of bubbles due to remelting can be suppressed, so that a decrease in impact resistance and sealing performance can be suppressed, and also, when a load is applied from the bus bar connected to the bus bar connection surface, the battery terminal is less likely to fall off.

[0053] 〔3〕In the above embodiment, the aspect where the return portion 16 is a plate-shaped part has been described, but it is not limited to such an aspect. FIG. 8 is a cross-sectional view showing a secondary battery 50 according to another embodiment. Note that reference numerals 51, 52, 53, 54, and S are attached to the sealing plate, attachment port, return portion, insulating member, and battery terminal of the secondary battery 50, respectively. For example, as shown in FIG. 8, in a longitudinal sectional view parallel to the extending direction D, the return portion 53 may be in an aspect where the outer surface 53a and the inner surface 53b (the surface 53b facing the inside of the attachment port 52) are stepped portions. In this case, the extending direction D is a direction parallel to the direction from the boundary P1 between the back surface 51b of the sealing plate 51 and the outer surface 53a of the return portion 53 to the tip P2 of the outer surface 53a of the return portion 53. Even in such an aspect, the generation of bubbles due to the remelting of the insulating member 54 is suppressed, so that the impact resistance and sealing performance of the secondary battery 50 can be suppressed from deteriorating. Further, as in this aspect, since the outer surface 53a and the inner surface 53b are stepped, the insulating member 54 is less likely to come off from the sealing plate 13, so that the battery terminal S is less likely to fall off from the sealing plate 51.

[0054] Note that the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with the configurations disclosed in other embodiments as long as no contradiction occurs. Further, 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

[0055] 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) 16: Return portion 17: Roughened portion 17a: Microprotrusions 40: Positive electrode insulating member (insulating member) 45: Negative electrode insulating member (insulating member) PS: Positive battery terminal (battery terminal) NS: Negative battery terminal (battery terminal) Ba, Bb: Bus bar connection surface D: Extension direction

Claims

1. A secondary battery comprising a housing having an opening and a sealing body for sealing the opening of the housing, wherein the sealing body includes a lid body having a mounting opening penetrating through the front and back surfaces thereof, a battery terminal having a bus bar connection surface and attached to the mounting opening of the lid body such that the bus bar connection surface is disposed on the surface side of the lid body, and a resin insulating member for insulating the lid body and the battery terminal, wherein the lid body includes a return portion extending from at least a part of the opening edge portion of the mounting opening toward the back surface side of the lid body, and a roughened portion formed of minute protrusions on the opening edge portion of the mounting opening and the return portion, wherein the insulating member is formed to cover the roughened portion formed on the mounting opening and the return portion and to fill the space between the mounting opening and the battery terminal in a state of being integrated with the lid body and the battery terminal, and the opening of the housing is sealed by the sealing body in a state where the boundary portion between the opening edge portion of the housing and the peripheral edge portion of the lid body is laser welded.

2. The secondary battery according to claim 1, wherein the angle formed by the direction orthogonal to the opening surface of the mounting opening and the extending direction of the return portion is 0° or more and 45° or less.

3. The secondary battery according to claim 1 or 2, wherein the return portion extends from the entire circumference of the opening edge portion of the mounting opening.

Images