Sealed battery and method for inspecting sealed battery

Abstract

To provide a sealed battery and a method for inspecting a sealed battery which can inspect the air tightness of a sealed battery without sealing an inspection gas in advance at the time of manufacturing the sealed battery.SOLUTION: The sealed battery according to the present disclosure includes a plurality of sealing mechanisms for sealing a sealed battery. The sealed battery has inspection holes 14h and 17h leading from the outside of the sealed battery to an inner space 19 in contact with the sealing mechanisms and used for inspecting the air tightness of the inner space 19.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a sealed battery and a method for inspecting a sealed battery. [Background technology]

[0002] Patent Document 1 describes a method for inspecting airtightness of a sealed battery and a technique related to the sealed battery. In the technique described in Patent Document 1, a sealed battery is fabricated by sandwiching a sealing material having a recess between a lid and a container inside a sealed container in a detection gas atmosphere, and then the detection gas in the sealed container is removed, and the airtightness is judged based on whether the detection gas accumulated in the recess leaks. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-026569 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technique described in Patent Document 1 requires the sealed battery to be pre-filled with the test gas when it is manufactured, which is a time-consuming manufacturing process.

[0005] The present disclosure has been made in consideration of the above-described situation, and provides a sealed battery and a sealed battery inspection method that make it possible to inspect the airtightness of a sealed battery without previously sealing in a test gas during the manufacture of the sealed battery. [Means for solving the problem]

[0006] The sealed battery of the present disclosure comprises a plurality of sealing mechanisms that seal the sealed battery, and an inspection hole that connects from the outside of the sealed battery to an internal space that is in contact with any of the plurality of sealing mechanisms and is used to inspect the airtightness of the internal space.

[0007] The sealed battery inspection method disclosed herein involves manufacturing a sealed battery to include a plurality of sealing mechanisms that seal the sealed battery and an inspection hole that communicates from the outside of the sealed battery to an internal space that is in contact with any of the plurality of sealing mechanisms and is used to inspect the airtightness of the internal space, and supplying gas through the inspection hole or supplying gas from the outside of the sealed battery to inspect the airtightness of the internal space. Effect of the Invention

[0008] The present disclosure makes it possible to provide a sealed battery and a method for inspecting a sealed battery that can inspect the airtightness of the sealed battery without sealing in a test gas in advance during the manufacture of the sealed battery. [Brief description of the drawings]

[0009] [Figure 1] 1 is a flow chart for explaining an example of a secondary battery manufacturing method including a secondary battery inspection method according to an embodiment. [Diagram 2] 4 is a schematic cross-sectional view showing an example of a member group in a part of a secondary battery according to an embodiment. FIG. [Diagram 3] 2 is a schematic cross-sectional view showing an example of a secondary battery to be inspected during production in the secondary battery production method of FIG. 1. [Figure 4] 2 is a schematic cross-sectional view showing an example of a method for inspecting the secondary battery of FIG. 1. [Diagram 5] 1. FIG. 4 is a schematic cross-sectional view showing another example of the method for inspecting the secondary battery in FIG. [Figure 6] 10A and 10B are schematic diagrams for explaining a secondary battery inspection method according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. Also, not all of the configurations described in the embodiments are necessarily essential as means for solving the problems.

[0011] (Embodiment) An example of a sealed battery inspection method and a sealed battery according to the present embodiment will be described with reference to Figures 1 to 5. The following description will be given on the assumption that the sealed battery is a secondary battery, but the same can be applied to a primary battery.

[0012] Fig. 1 is a flow diagram for explaining an example of a secondary battery manufacturing method including a secondary battery inspection method according to the present embodiment (hereinafter referred to as the present manufacturing method). Fig. 2 is a schematic cross-sectional view showing an example of a member group in a part of a secondary battery according to the embodiment. Fig. 3 is a schematic cross-sectional view showing an example of a secondary battery to be inspected in the middle of being manufactured by the present manufacturing method. Fig. 4 and Fig. 5 are schematic cross-sectional views showing an example and another example of an inspection step in the present manufacturing method, respectively.

[0013] In this manufacturing method, first, each member that will be a part of the secondary battery according to the present embodiment (hereinafter, the present battery) is laminated (step S1). Here, the members that make up the present battery can include a member group 10a exemplified in FIG. 2 as secondary battery members.

[0014] The member group 10a includes a polarity terminal 11 of one of the negative and positive electrodes of the secondary battery. As illustrated in FIG. 2, the polarity terminal 11 can be composed of a bottom portion and a lead-out portion extending therefrom, and the shape of the lead-out portion can be, for example, cylindrical. The member group 10a further includes a sealant 12, a lid cover 13, a gasket 14, sealants 15 and 16, and an external terminal 17. The sealants 12, 15 and 16, the gasket 14, and the external terminal 17 each have, for example, a ring-like shape. The outer periphery of the gasket 14 can include a thick portion that covers the periphery of the external terminal 17. Note that the same structure can be adopted for the other electrode of this battery, which will not be described, but the shape of the other electrode may be different from that of the one electrode.

[0015] The sealant 12 is disposed between the lid cover 13 and the bottom surface of the polar terminal 11, and is a member that seals the gap between the lid cover 13 and the polar terminal 11. Hereinafter, the sealing mechanism provided by the sealant 12 will be referred to as the first sealing mechanism.

[0016] The lid cover 13 is a cover for a container that houses the electrode assembly of the battery. The electrode assembly and the container are not shown in Fig. 2 etc. The external terminal 17 is electrically connected to the polarity terminal 11 and is a terminal for connecting the battery to an external load.

[0017] The sealant 15 is disposed between the lower surface of the gasket 14 and the upper surface of the lid cover 13, and is a member that seals between the gasket 14 and the lid cover 13. The sealant 16 is disposed between the upper surface of the gasket 14 and the lower surface of the external terminal 17, and is a member that seals between the gasket 14 and the external terminal 17. The sealant 15, the gasket 14, and the sealant 16 are members that seal between the lid cover 13 and the external terminal 17, and hereinafter, a sealing mechanism formed by these members is referred to as a second sealing mechanism. In this way, the present battery is provided with a first and a second sealing mechanism that seal between the members that constitute the present battery. In other words, the present battery is provided with a double mechanism that seals the inside of the secondary battery.

[0018] In step S1, the member group 10a is layered as shown in Fig. 3 in the order shown in Fig. 2. That is, in step S1, the member group 10a is layered such that the bottom surface of the polar terminal 11 and the external terminal 11 sandwich the lid cover 13 and the gasket 14 layered thereon. Then, when the members are layered, the first and second sealing mechanisms described above are provided.

[0019] In order to achieve sealing in the first and second sealing mechanisms, in this manufacturing method, the member group 10a laminated in step S1 is fixed by crimping (step S2), and the lead-out portion of the polar terminal 11 is welded to the external terminal 17 by laser welding or the like (step S3). This produces the secondary battery 10b shown in FIG.

[0020] The crimping process in step S2 can be performed, for example, by pressing the upper surface of the polar terminal 11 with a member having a convex portion (not shown). By such pressing, a concave portion 11k having a shape corresponding to the convex portion is formed on the upper surface of the polar terminal 11. In FIG. 3, the polar terminal 11 after crimping is shown as polar terminal 11b. The position of welding in step S3 can be the position shown by welded portion 18 in FIG. 3. By the crimping process and welding process as described above, it is possible to increase the airtightness of the portions other than the inspection holes 14h and 17h described below.

[0021] After the member group 10a is crimped and welded, the secondary battery 10b has an internal space 19 surrounded by the polar terminal 11, the sealant 12, the lid cover 13, the gasket 14, the sealants 15 and 16, and the external terminal 17. The internal space 19 is a space formed by the first sealing mechanism and the second sealing mechanism connecting other members in this manner. In other words, the internal space 19 is a space in contact with both the first and second sealing mechanisms.

[0022] This secondary battery 10b is the subject of inspection. However, in this embodiment, in order to inspect the airtightness of the internal space 19, an inspection hole 14h and an inspection hole 17h are formed in the gasket 14 and the external terminal 17, respectively. The inspection hole 14h and the inspection hole 17h are formed at positions communicating with each other. The method of forming the inspection holes 14h and 17h does not matter. The inspection holes 14h and 17h communicate from the outside of the secondary battery 10b to be inspected to the internal space 19 that is in contact with both the first and second sealing mechanisms, and are examples of inspection holes used to inspect the airtightness of the internal space 19. The inspection holes 14h and 17h can also be called communication holes.

[0023] In this manner, in this manufacturing method, the secondary battery 10b is manufactured so as to be provided with first and second sealing mechanisms for sealing the battery, and the inspection holes 14h and 17h.

[0024] After step S3, the sealed portion is inspected for leakage (step S4). The sealed portion refers to the internal space 19. In step S4, an inspection of the airtightness of the internal space 19 is performed by supplying gas through the inspection hole 17h or by supplying gas from outside the secondary battery 20b. In either case, the flow path of the inspection gas is formed by the inspection holes 14h, 17h and the internal space 19. In the following, an example in which the inspection gas is helium is given, but other gases may be used.

[0025] The inspection in step S4 is performed by housing the secondary battery 10b to be inspected, manufactured as described above, in a container 20A, as illustrated in Fig. 4. The container 20A includes a gas supply port 22A for supplying helium to the inspection hole 17h, and a detection port 23A.

[0026] The gas supply port 22A is not connected to the internal space 21A formed by the inner wall of the container 20A and the outside of the secondary battery 10b, and is formed to supply helium only from the inspection hole 17h. Helium is supplied to the internal space 19 from the gas supply port 22A, and the internal space 19 is filled with helium. The detection port 23A is connected to the internal space 21A, and by reducing the pressure outside the container 20A, when helium leaks from at least one of the first and second sealing mechanisms, the helium is caused to flow to the outside of the container 20A. A sensor (not shown) for detecting helium is provided on the inner wall of the detection port 23A or outside the container 20A. Note that the reduction in pressure enables such detection in a short time and is not essential for the inspection. The above sensor may be a sensor that measures the amount of helium leaking to the outside, and may detect that helium has leaked when a predetermined amount or more has leaked, for example. Although not shown in FIG. 4, a space is provided between gas supply port 22A and detection port 23A so that the sensor does not directly detect the helium supplied from gas supply port 22A.

[0027] Alternatively, the inspection in step S4 can be performed by housing the secondary battery 10b in a container 20B, as illustrated in Fig. 5. The container B includes a gas supply port 22B for supplying helium to an internal space 21B formed between the inner wall of the container 20B and the outside of the secondary battery 10b, and a detection port 23B.

[0028] The gas supply port 22B communicates with the internal space 21B, but the detection port 23B is formed so that helium does not flow in from the inspection hole 17h. Helium is supplied to the internal space 21B from the gas supply port 22B, and the internal space 21B is filled with helium. The detection port 23B does not communicate with the internal space 21B, and by depressurizing the outside of the container 20B, when helium flows into the internal space 19 from at least one of the first and second sealing mechanisms, the helium is caused to flow out of the container 20B from the inspection holes 14h and 17h. A sensor for detecting helium is provided on the inner wall of the detection port 23B or outside the container 20B, as described in FIG. 4. Although not shown in FIG. 5, a space is partitioned between the gas supply port 22B and the detection port 23B so that the sensor does not directly detect the helium supplied from the gas supply port 22B.

[0029] With either of the inspection methods shown in FIGS. 4 and 5, if there is an error in one of the sealing mechanisms and helium passes through, as indicated by the thick arrow in each diagram, the helium leak can be detected and defective products can be reliably detected.

[0030] Finally, the manufacturing process is completed by sealing the inspection holes (step S5). The sealing in step S5 may be performed by any method that can achieve sealing, such as by pressing a member that is slightly larger than the inspection holes 14h and 17h into the holes and welding the holes as necessary, or by inserting an airtight resin or the like and hardening the resin.

[0031] That is, the present battery may include a member for sealing the inspection hole after inspection. That is, the present battery to be distributed on the market may be the secondary battery 10b to be inspected, in which the inspection holes 14h, 17h are sealed with a member (not shown). In this manner, the present battery is stacked and assembled in a configuration excluding the member in step S1, and is sealed with the member after inspection. The member may be a member for sealing only the inspection hole 14h of the gasket 14 or only the inspection hole 17h of the external terminal 17.

[0032] The battery manufactured in this way has a double sealing mechanism, and therefore has high airtightness. In fact, there is a demand for longer battery life and use in harsher environments in recent years, and the battery manufactured in this way can guarantee the performance that can meet these demands. For example, when an elastic body such as rubber is used as a sealing member for the sealing mechanism, the cross-sectional area and length of the sealing member determine the sealing performance in order to guarantee the hermeticity of the battery. In order to double the sealing performance without changing the material, it is necessary to double the sealing length. However, battery cells have dimensional constraints in the thickness direction, and it is difficult to ensure the sealing length, especially for batteries with small capacity. In contrast, the battery manufactured in this way has a double sealing mechanism as described above, and therefore can guarantee the performance that can meet the above demands.

[0033] According to the secondary battery inspection method of the present embodiment, the airtightness of the secondary battery can be inspected without sealing the test gas in advance during the manufacture of the secondary battery. The inspection of the airtightness means the soundness of the sealing mechanism. In particular, in this inspection, even if there are two sealed parts, i.e., sealing mechanisms, as shown in the example, all of them can be inspected reliably and easily.

[0034] Of course, even if the secondary battery 10b has three or more sealing mechanisms, the sealed state of all the sealing mechanisms can be inspected reliably and easily. The inspection hole may be formed as a hole that communicates from the outside of the secondary battery to the internal space in contact with any of the sealing mechanisms and is used to inspect the airtightness of the internal space.

[0035] The effects of the above-mentioned secondary battery inspection method will be described by comparison with a comparative example shown in Fig. 6. Fig. 6 is a schematic diagram for explaining the secondary battery inspection method according to the comparative example. In the secondary battery inspection method according to the comparative example, the inspection method for a secondary battery having only a single sealing mechanism is directly applied to a secondary battery having a double sealing mechanism.

[0036] The secondary battery 50 according to the comparative example is the secondary battery 10b, which includes a gasket 54 without an inspection hole 14h instead of the gasket 14, and an external terminal 57 without an inspection hole 17h instead of the external terminal 17. The container 60 according to the comparative example is sealed with a circumferential contact 64u on the upper surface of the lid cover 13 to form an internal space 61u, and is sealed with a circumferential contact 64d on the lower surface of the lid cover 13 to form an internal space 61d. The container 60 further includes a gas supply port 62 for supplying helium to fill the internal space 61u or the internal spaces 61u and 61d, and a detection port 63 equipped with a sensor for detecting helium.

[0037] However, in the comparative example, as shown by the thick arrow in Fig. 6, if the first sealing mechanism formed by gasket 54 and sealing materials 15, 16 is unsound and allows helium to pass, and the second sealing mechanism formed by sealing material 12 is sound and does not allow helium to pass, it is determined to be normal. Conversely, in the comparative example, it is also determined to be normal when the first sealing mechanism is sound and the second sealing mechanism is unsound. That is, in the secondary battery 50 according to the comparative example, the inspection result is normal in these cases, and defective products will be released.

[0038] In order to verify the effect of this manufacturing method over such a comparative example, a lid assembly was fabricated by integrating the positive and negative terminals, the sealant, and the lid cover. Then, a secondary battery with inspection holes 14h, 17h like this battery, and a secondary battery without inspection holes 14h, 17h like the secondary battery 50 according to the comparative example were fabricated. Here, the sealants 12, 15, 16 used in the first and second sealing mechanisms were flat rings made of vinylidene fluoride-based fluororubber, with an outer diameter of φ7, an inner diameter of φ4, and a thickness of 1 mm. The volume of the internal space 19 was 12 mm. 3 For verification purposes, a flat ring with a crack was used in the first sealing mechanism to simulate an error product.

[0039] In the inspection method shown in Fig. 4, the internal space 19 was filled with helium at 0.1 MPa from the inspection hole 17h after depressurization and degassing. In the inspection method shown in Fig. 5, the lid assembly was enclosed, and after depressurization and degassing, the internal space 21B was filled with helium to 0.1 MPa, and depressurized from the inspection hole 17h. The depressurization was set to 0.001 MPa using a vacuum pump.

[0040] As a result, in the inspection method shown in Fig. 4, internal space 19 was filled with helium, and the detection result at detection port 23A was poor (NG). In the inspection method shown in Fig. 5, when internal space 19 was depressurized from inspection holes 14h, 17h, helium leaked, and the detection result at detection port 23B was poor (NG). On the other hand, in the comparative example, internal space 19 was filled with helium, but even when internal space 19 was depressurized from detection port 63, helium did not leak into internal space 61d, and the detection result at detection port 63 was good (OK).

[0041] As described above, it was confirmed that the inspection methods of either Figure 4 or Figure 5 can reliably and easily inspect the soundness of each of the first and second sealing mechanisms, and prevent the outflow of defective products as in the comparative example.

[0042] (Alternative examples, etc.) The present invention is not limited to the above embodiment, and can be modified as appropriate without departing from the spirit of the present invention. For example, in the above embodiment, only one example of the shape of each member constituting the sealed battery is described, but the shape may be such that each member can fulfill its function, and the material of each member may be such that each member can fulfill its function. Furthermore, the group of members described in the above embodiment is merely one example of the group of members constituting the multiple sealing structures in the sealed battery, and some of the members may be configured as an integrated set, or some of the members may be configured as multiple members. [Explanation of symbols]

[0043] 10a...group of parts of secondary battery, 10b...secondary battery to be inspected, 11...polar terminal, 11b...polar terminal after crimping, 11k...recess, 12, 15, 16...sealing material, 13...lid cover, 14...gasket, 14h...inspection hole, 17...external terminal, 17h...inspection hole, 18...welded portion, 19...internal space, 20A, 20B...container, 21A, 21B...internal space of container, 22A, 22B...gas supply port, 23A, 23B...detection port.

Claims

1. A sealed battery, A plurality of sealing mechanisms for sealing the sealed battery; an inspection hole that communicates from the outside of the sealed battery with an internal space that is in contact with any of the plurality of sealing mechanisms and is used to inspect the airtightness of the internal space; A sealed battery comprising:

2. a member for sealing the inspection hole after the inspection; 2. The sealed battery according to claim 1.

3. A sealed battery is manufactured to include a plurality of sealing mechanisms that seal the sealed battery, and an inspection hole that communicates from the outside of the sealed battery with an internal space that contacts any of the plurality of sealing mechanisms and is used to inspect the airtightness of the internal space; supplying gas through the inspection hole or from the outside of the sealed battery to inspect the airtightness of the internal space; Sealed battery inspection method.

4. sealing the inspection hole after the inspection; 4. The method for inspecting a sealed battery according to claim 3.

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