Sealed battery and method for testing a 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 Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique described in Patent Document 1, it is necessary to enclose a detection gas in advance during the manufacture of the sealed battery, which is troublesome in the manufacturing process.

[0005] The present disclosure has been made in view of the above actual situation, and provides a sealed battery and a method for inspecting a sealed battery that can inspect the airtightness of the sealed battery without enclosing a detection gas in advance during the manufacture of the sealed battery.

Means for Solving the Problems

[0006] The sealed battery according to the present disclosure includes a plurality of sealing mechanisms for sealing the sealed battery, and an inspection hole that communicates with an internal space in contact with any of the plurality of sealing mechanisms from the outside of the sealed battery and is used for inspecting the airtightness of the internal space.

[0007] The sealed battery inspection method according to this disclosure is manufactured to include a sealed battery comprising a plurality of sealing mechanisms that seal the sealed battery, and an inspection hole that communicates with an internal space in contact with any of the plurality of sealing mechanisms from the outside of the sealed battery and is used to inspect the airtightness of the internal space, and the inspection of the airtightness of the internal space is performed by supplying gas from the inspection hole or by supplying gas from the outside of the sealed battery. [Effects of the Invention]

[0008] This disclosure provides a sealed battery and a sealed battery inspection method that enable the inspection of the airtightness of a sealed battery without pre-filling it with an inspection gas during manufacturing. [Brief explanation of the drawing]

[0009] [Figure 1] This is a flowchart illustrating an example of a secondary battery manufacturing method, including a secondary battery inspection method according to an embodiment. [Figure 2] This is a schematic cross-sectional view showing an example of a group of components in a part of a secondary battery according to an embodiment. [Figure 3] Figure 1 is a schematic cross-sectional view showing an example of a secondary battery being inspected during the manufacturing process. [Figure 4] Figure 1 is a schematic cross-sectional view showing an example of a secondary battery inspection method. [Figure 5] Figure 1 is a schematic cross-sectional view showing another example of a secondary battery inspection method. [Figure 6] This is a schematic diagram illustrating the secondary battery inspection method related to the comparative example. [Modes for carrying out the invention]

[0010] The present invention will be described below through embodiments, but the claims are not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential for solving the problem.

[0011] (Embodiment) An example of a sealed battery inspection method and a sealed battery according to this embodiment will be explained using Figures 1 to 5. The following explanation assumes that the sealed battery is a secondary battery, but the same principles apply to primary batteries as well.

[0012] Figure 1 is a flowchart illustrating an example of a secondary battery manufacturing method (hereinafter referred to as "this manufacturing method") that includes a secondary battery inspection method according to this embodiment. Figure 2 is a schematic cross-sectional view showing an example of a group of components in a part of a secondary battery according to this embodiment. Figure 3 is a schematic cross-sectional view showing an example of a secondary battery to be inspected during the manufacturing process in this manufacturing method. Figures 4 and 5 are schematic cross-sectional views showing an example and another example of the inspection process in this manufacturing method, respectively.

[0013] In this manufacturing method, first, the components that will make up the secondary battery according to this embodiment (hereinafter referred to as "this battery") are stacked (step S1). Here, the components that make up this battery may include the group of components 10a illustrated in Figure 2 as secondary battery components.

[0014] The component group 10a includes a polarity terminal 11 for one of the electrodes, the negative electrode and the positive electrode, in the secondary battery. The polarity terminal 11 can be composed of a bottom portion and an extension portion extending therefrom, and the shape of the extension portion can be, for example, cylindrical. The component group 10a further includes a sealing material 12, a lid cover 13, a gasket 14, sealing materials 15, 16, and an external terminal 17. The sealing materials 12, 15, 16, the gasket 14, and the external terminal 17 have, for example, a ring shape. The outer circumference of the gasket 14 may have a thickened portion that covers the periphery of the external terminal 17. The battery can employ a similar structure for the other electrode, which is not described, but its shape may differ from that of the other electrode.

[0015] The sealing material 12 is positioned between the lid cover 13 and the polarity terminal 11 at the bottom surface, and is a component that seals the space between the lid cover 13 and the polarity terminal 11. Hereinafter, the sealing mechanism provided by the sealing material 12 will be referred to as the first sealing mechanism.

[0016] The lid cover 13 is a cover that serves as the lid of the container for housing the electrode body in this battery. Note that the electrode body and the container are not shown in FIG. 2 and the like. The external terminal 17 is a terminal that is electrically connected to the polarity terminal 11 and connects this battery to an external load.

[0017] The sealing material 15 is a member that is disposed between the lower surface of the gasket 14 and the upper surface of the lid cover 13 and seals between the gasket 14 and the lid cover 13. The sealing material 16 is a member that is disposed between the upper surface of the gasket 14 and the lower surface of the external terminal 17 and seals between the gasket 14 and the external terminal 17. The sealing material 15, the gasket 14, and the sealing material 16 are members that seal between the lid cover 13 and the external terminal 17. Hereinafter, the sealing mechanism constituted by these is referred to as the second sealing mechanism. Thus, this battery includes the first and second sealing mechanisms that seal between the members constituting this battery. That is, this battery is provided with a double mechanism for sealing the inside of the secondary battery.

[0018] In step S1, the member group 10a is laminated as shown in FIG. 3 in the order shown in FIG. 2. That is, in step S1, the member group 10a is laminated such that the bottom surface portion of the polarity terminal 11 and the external terminal 11 sandwich the gasket 14 laminated on the lid cover 13 and its upper layer. And the above-described first and second sealing mechanisms are provided at the time of lamination.

[0019] And in order to achieve the sealing by the first and second sealing mechanisms, in this manufacturing method, the member group 10a laminated in step S1 is fixed by caulking (step S2), and the lead-out portion of the polarity terminal 11 and the external terminal 17 are welded by laser welding or the like (step S3). Thereby, the secondary battery 10b shown in FIG. 3 is manufactured.

[0020] The caulking process in step S2 can be executed, for example, by pressing the upper surface of the polarity terminal 11 with a member provided with 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 polarity terminal 11. In FIG. 3, the polarity terminal 11 after caulking is shown as the polarity terminal 11b. Also, the welding position in step S3 can be the position indicated by the welding portion 18 in FIG. 3. By the caulking process and the welding process as described above, the airtightness of portions other than the inspection holes 14h and 17h described later can be enhanced.

[0021] In the secondary battery 10b after caulking and welding the member group 10a, an internal space 19 surrounded by the polarity terminal 11, the sealing material 12, the lid cover 13, the gasket 14, the sealing materials 15 and 16, and the external terminal 17 is formed. The internal space 19 is a space formed by connecting between other members by the first sealing mechanism and the second sealing mechanism in this way. That is, the internal space 19 is a space in contact with both the first and second sealing mechanisms.

[0022] This secondary battery 10b is the inspection target. However, in the present embodiment, inspection holes 14h and inspection holes 17h are formed in the gasket 14 and the external terminal 17, respectively, in order to inspect the airtightness of the internal space 19. 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 is not limited. The inspection holes 14h and 17h are an example of inspection holes that communicate from the outside of the secondary battery 10b to be inspected to the internal space 19 in contact with both the first and second sealing mechanisms and are used for inspecting the airtightness of the internal space 19. The inspection holes 14h and 17h can also be referred to as communication holes.

[0023] Thus, in this manufacturing method, the secondary battery 10b is manufactured to include the first and second sealing mechanisms for sealing the battery and the inspection holes 14h and 17h.

[0024] After step S3, the leak of the sealed area is inspected (step S4). The sealed area refers to the internal space 19. In step S4, the airtightness of the internal space 19 is inspected by supplying gas from 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 between the inspection holes 14h, 17h and the internal space 19. The following example uses helium as the inspection gas, but other gases may also be used.

[0025] The inspection in step S4 is carried out by housing the secondary battery 10b to be inspected, manufactured as described above, inside the container 20A, as illustrated in Figure 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 does not communicate with the internal space 21A formed by the inner wall of the container 20A and the outside of the secondary battery 10b, and is configured to supply helium only from the inspection hole 17h. Helium is supplied to the internal space 19 from this gas supply port 22A, and the internal space 19 is filled with helium. The detection port 23A communicates with the internal space 21A, and by depressurizing the outside of the container 20A, if helium leaks from at least one of the first and second sealing mechanisms, the helium is allowed to flow to the outside of the container 20A. The inner wall of the detection port 23A or the outside of the container 20A is equipped with a sensor (not shown) that detects helium. Note that depressurization enables such detection in a short time and is not essential for inspection. The above sensor may be a sensor that measures the amount of helium leaking to the outside, for example, it is sufficient to detect that helium has leaked if it leaks more than a predetermined amount. Although not shown in Figure 4, a space is partitioned between the gas supply port 22A and the detection port 23A to prevent the sensor from directly detecting the helium supplied from the gas supply port 22A.

[0027] Alternatively, the inspection in step S4 may be carried out with the secondary battery 10b housed in a container 20B, as illustrated in Figure 5. Container B includes a gas supply port 22B for supplying helium to the internal space 21B formed by the inner wall of 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 a detection port 23B is formed to prevent helium from flowing in through the inspection hole 17h. Helium is supplied to the internal space 21B from this 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 reducing the pressure outside the container 20B, if helium flows into the internal space 19 from at least one of the first and second sealing mechanisms, that helium is allowed to flow out of the container 20B through the inspection holes 14h and 17h. A sensor for detecting helium is provided on the inner wall of the detection port 23B or on the outside of the container 20B, similar to the one described in Figure 4. Although not shown in Figure 5, a space is partitioned between the gas supply port 22B and the detection port 23B so that this sensor does not directly detect the helium supplied from the gas supply port 22B.

[0029] With either inspection method shown in Figures 4 and 5, for example, as indicated by the thick arrows in each figure, if there is an error in either sealing mechanism and helium passes through, it is possible to detect the helium leak and reliably identify defective products.

[0030] Finally, the manufacturing process is completed by sealing the inspection holes (step S5). The sealing in step S5 can be carried out by any method that provides a seal, such as pressing a component slightly larger than the inspection holes 14h and 17h into the holes and welding if necessary, or inserting a highly airtight resin and allowing it to harden.

[0031] In other words, this battery may be equipped with a component that seals the inspection holes after inspection. That is, this battery intended for distribution to the market may have the inspection holes 14h and 17h of the secondary battery 10b to be inspected sealed with a component not shown. Thus, this battery is stacked and assembled in step S1 with the component removed, and then sealed with the component after inspection. Note that the component may be a component that seals 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 manner features a double sealing mechanism, resulting in high airtightness. In fact, there is a growing demand for longer battery life and use in harsher environments, and this battery can be manufactured with the performance to meet these demands. For example, when using an elastic material such as rubber as the sealing component in the sealing mechanism, the cross-sectional area and length of the sealing component affect the sealing performance in order to guarantee the sealing performance of the battery. To double the sealing performance without changing the material, the sealing length needs to be doubled. However, battery cells have dimensional constraints in the thickness direction, and it is particularly difficult to secure the sealing length for batteries with small capacity. In contrast, this battery employs a double sealing mechanism as described above, so it can be manufactured with the performance to meet the above demands.

[0033] Furthermore, according to the secondary battery inspection method of this embodiment, the airtightness of the secondary battery can be inspected without pre-filling it with inspection gas during the manufacturing process. Note that the airtightness inspection refers to the integrity of the sealing mechanism. In particular, this inspection allows for the reliable and easy inspection of both sealing points, i.e., sealing mechanisms, even if there are two as illustrated.

[0034] Of course, even if the secondary battery 10b is configured to have three or more sealing mechanisms, the sealing condition of all the sealing mechanisms can be reliably and easily inspected in the same manner. The inspection holes only need to be formed to communicate with the internal space in contact with any of the multiple sealing mechanisms from the outside of the secondary battery and to be used for inspecting the airtightness of the internal space.

[0035] The effectiveness of the secondary battery inspection method described above will be explained by comparing it with the comparative example shown in Figure 6. Figure 6 is a schematic diagram illustrating the secondary battery inspection method related to the comparative example. In the secondary battery inspection method related to the comparative example, the inspection method for secondary batteries equipped with only a single sealing mechanism is applied directly to secondary batteries equipped with a double sealing mechanism.

[0036] The comparative example secondary battery 50 is equipped with a gasket 54 in place of the gasket 14 in the secondary battery 10b, which does not have an inspection hole 14h, and an external terminal 57 in place of the external terminal 17, which does not have an inspection hole 17h. The comparative example container 60 is sealed to the secondary battery 50 by a circumferential contact 64u on the upper surface of the lid cover 13 to form an internal space 61u, and by a circumferential contact 64d on the lower surface of the lid cover 13 to form an internal space 61d. Furthermore, the container 60 is equipped with a gas supply port 62 for supplying helium to fill the internal space 61u or the internal spaces 61u,61d, and a detection port 63 equipped with a sensor for detecting helium.

[0037] However, in the comparative example, as shown by the thick arrows in Figure 6, the first sealing mechanism, composed of gasket 54 and sealants 15 and 16, is unhealthy and allows helium to pass through, while the second sealing mechanism, composed of sealant 12, is healthy and does not allow helium to pass through, and this is considered normal. Conversely, in the comparative example, the first sealing mechanism is healthy and the second sealing mechanism is unhealthy, and this is also considered normal. In other words, in the secondary battery 50 of the comparative example, the inspection result will be "normal" in these cases, resulting in defective products being released.

[0038] To verify the effectiveness of this manufacturing method against such comparative examples, a lid assembly was fabricated by integrating the positive electrode terminal, negative electrode terminal, sealing material, and lid cover. Then, a secondary battery with inspection holes 14h and 17h, like the present battery, and a secondary battery without inspection holes 14h and 17h, like the secondary battery 50 in the comparative example, were fabricated. Here, the sealing materials 12, 15, and 16 used in the first and second sealing mechanisms were flat rings made of polyvinylidene 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 mm³. 3 The adjustments were made accordingly. Furthermore, for verification purposes, a cracked flat ring was used in the first sealing mechanism to simulate a defective product.

[0039] In the inspection method shown in Figure 4, helium was filled into the internal space 19 at 0.1 MPa after degassing through the inspection hole 17h. In the inspection method shown in Figure 5, the lid assembly was enclosed and degassed under reduced pressure, then the internal space 21B was filled with helium at 0.1 MPa, and depressurization was performed through the inspection hole 17h. The depressurization was performed at 0.001 MPa using a vacuum pump.

[0040] As a result, in the inspection method shown in Figure 4, helium filled the internal space 19, and the detection result at detection port 23A was poor (NG). In the inspection method shown in Figure 5, when the internal space 19 was depressurized from inspection holes 14h and 17h, helium leaked, and the detection result at detection port 23B was poor (NG). On the other hand, in the comparative example, although the internal space 19 was filled with helium, no helium leaked into the internal space 61d even when the internal space 19 was depressurized from detection port 63, and the detection result at detection port 63 was good (OK).

[0041] As described above, both inspection methods shown in Figures 4 and 5 can reliably and easily inspect the integrity of the first and second sealing mechanisms, and it was confirmed that they can prevent the outflow of defective products as in the comparative example.

[0042] (Alternative examples, etc.) It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. For example, in the above embodiments, only one example of the shape of each component constituting the sealed battery was given, but any shape that can perform the function of each component is acceptable, and the material of each component should also be suitable for performing that function. Furthermore, the group of components described in the above embodiments is merely one example of a group of components constituting multiple sealing structures in a sealed battery, and some sets of these components may be configured as a single unit, or some of these components may be composed of multiple components. [Explanation of Symbols]

[0043] 10a...Part of the components of the secondary battery, 10b...Secondary battery to be inspected, 11...Polarity terminal, 11b...Polarity 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 part, 19...Internal space, 20A, 20B...Container, 21A, 21B...Internal space of the container, 22A, 22B...Gas supply port, 23A, 23B...Detection port.

Claims

1. It is a sealed battery, A plurality of sealing mechanisms, each including at least a first sealing mechanism for sealing the inside of the sealed battery and a second sealing mechanism for sealing the outside of the sealed battery, arranged to seal the same sealing area, An inspection hole is provided, accessible from the outside of the sealed battery, that communicates with an internal space formed between the first sealing mechanism and the second sealing mechanism, and that is in contact with both the first and second sealing mechanisms, and is used for testing the airtightness of the internal space. A sealed battery equipped with [a specific feature / feature].

2. The first sealing mechanism includes a first sealing material that seals the space between the polar terminals of the sealed battery and the lid cover, The second sealing mechanism includes a gasket disposed between the lid cover and the external terminals of the sealed battery, a second sealing material that seals the space between the gasket and the lid cover, and a third sealing material that seals the space between the gasket and the external terminals. A sealed battery according to claim 1.

3. The inspection hole includes a first hole formed in the external terminal and a second hole formed in the gasket, and the first hole and the second hole communicate with each other, thereby communicating with the internal space. The sealed battery according to claim 2.

4. The system includes a member for sealing the inspection hole after the inspection. A sealed battery according to any one of claims 1 to 3.

5. A sealed battery is manufactured to include a plurality of sealing mechanisms, each comprising at least a first sealing mechanism that seals the inside of the sealed battery and a second sealing mechanism that seals the outside of the sealed battery, arranged to seal the same sealed area; and an inspection hole, accessible from the outside of the sealed battery, that communicates with an internal space formed between the first sealing mechanism and the second sealing mechanism and in contact with both the first and second sealing mechanisms, and is used to test the airtightness of the internal space. The airtightness of the internal space is inspected by supplying gas through the inspection hole or by supplying gas from outside the sealed battery. A method for testing sealed batteries.

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