Battery pack

Abstract

Provided is a battery pack capable of discharging high-pressure gas from a desired position of a case. A battery pack (100) is provided with: one or more secondary battery cells (1) in which a safety valve is provided in an outer can; an exterior case (10) that accommodates one or more secondary battery cells (1), and in a part of which is formed a vent hole (13) for releasing a high-pressure gas to the outside when the relief valve of the secondary battery cell (1) is opened and the high-pressure gas is discharged; and a label (20) that is adhered to the periphery of the exhaust hole (13) of the exterior case (10) and blocks the exhaust hole (13). The label (20) is provided with a breakage starting point part (22) in a part of an adhesive surface to the outer case (10).

Description

Technical Field

[0001] The present disclosure relates to battery packs. Background Art

[0002] In order to use rechargeable secondary batteries such as lithium-ion secondary batteries to drive electrical equipment, a battery pack that contains secondary battery cells in a shell is used (for example, Patent Document 1). In such a battery pack, when some abnormality occurs in the secondary battery cells, high-pressure gas is stored in the battery pack from the secondary battery cells. In this case, sometimes a vent hole is formed in a part of the shell to allow the gas to be discharged to the outside of the shell. Normally, the vent hole is not used, so in order to prevent foreign matter from entering the shell through the vent hole, it is considered to seal the vent hole with a label. If it is this structure, then in the case of Fig. 8A When the internal pressure of the housing 810 increases, Figure 8B As shown, the label 820 is broken due to the pressure, and the high-pressure gas can be discharged to the outside of the housing 810 through the exhaust hole.

[0003] However, in this structure, when the high-pressure gas is discharged from the broken part of the tag to the outside of the housing, it is difficult to predict in advance which part of the tag is broken, and there is a problem that it is difficult to accurately control the discharge position and direction of the high-pressure gas.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2019 / 163550 Summary of the invention

[0007] Problems to be solved by the invention

[0008] One of the objects of the present disclosure is to provide a battery pack capable of discharging high-pressure gas from a desired position of a casing.

[0009] Means for solving problems

[0010] A battery pack involved in one embodiment of the present invention comprises: one or more secondary battery cells, a safety valve is provided in an outer can; an outer shell, which accommodates the one or more secondary battery cells and has a vent hole formed in a portion for releasing the high-pressure gas to the outside when the safety valve of the secondary battery cell opens and discharges the high-pressure gas; and a label adhered to the periphery of the vent hole of the outer shell to seal the vent hole, and the label is provided with a rupture starting point portion in a portion of the bonding surface with the outer shell.

[0011] Effects of the Invention

[0012] According to a battery pack involved in one aspect of the present invention, if high-pressure gas is released from the safety valve into the outer casing, the high-pressure gas is broken from the position where the strength is intentionally weakened through the breaking starting point of the label, thereby accurately controlling the discharge position of the high-pressure gas and improving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a perspective view showing the battery pack according to the first embodiment.

[0014] Figure 2 It is shown Figure 1 An exploded perspective view of the surface of a battery pack.

[0015] Figure 3 It is shown Figure 1 An exploded perspective view of the interior of a battery pack.

[0016] Figure 4 yes Figure 1 A cross-sectional perspective view taken along line IV-IV.

[0017] Figure 5 yes Figure 4 An enlarged cross-sectional view of the main parts.

[0018] Figure 6 Observed from below Figure 2 An enlarged exploded perspective view of .

[0019] Figure 7 yes Figure 6 Exploded perspective view of a label.

[0020] Fig. 8A is a schematic cross-sectional view showing a state in which the internal pressure of a battery pack according to a comparative example increases. Figure 8B It shows that the label is from Fig. 8A A three-dimensional diagram of the state in which the gas is discharged after being peeled off.

[0021] Fig. 9A is a schematic cross-sectional view showing a state in which the internal pressure of the battery pack according to the first embodiment increases. Fig. 9B The slit portion is shown from Fig. 9A A three-dimensional diagram of the state in which the gas is discharged after being damaged.

[0022] Fig.10 It is an exploded perspective view showing a label of a battery pack according to a modification example, as seen obliquely from below.

[0023] Fig.11A is a plan view of the double-sided tape of the label of the battery pack according to the first embodiment as viewed from the front side, Fig. 11B It shows Fig.11A Schematic diagram of the results of CAE. Fig. 11C It is shown in Fig.11A A top view of a label having a slit portion formed in a double-sided tape.

[0024] Fig. 12A is a plan view of the double-sided tape of the label of the battery pack according to the second embodiment as viewed from the front side, Fig. 12B It shows Fig. 12A Schematic diagram of the results of CAE. Fig. 12C It is shown in Fig. 12A A top view of a label having a slit portion formed in a double-sided tape.

[0025] Fig.13A is a plan view of the double-sided tape of the label of the battery pack according to the third embodiment as viewed from the front side, Fig. 13B It shows Fig.13A Schematic diagram of the results of CAE. Fig. 13C It is shown in Fig.13A A top view of a label having a slit portion formed in a double-sided tape.

[0026] Fig.14A is a plan view of the double-sided tape of the label of the battery pack according to the fourth embodiment as viewed from the front side, Fig. 14B It shows Fig.14A Schematic diagram of the results of CAE. Fig. 14C It is shown in Fig.14A A top view of a label having a slit portion formed in a double-sided tape.

[0027] Fig.15A is a plan view of the double-sided tape of the label of the battery pack according to the fifth embodiment as viewed from the front side, Fig. 15B It shows Fig.15A Schematic diagram of the results of CAE. Fig. 15C It is shown in Fig.15A A top view of a label having a slit portion formed in a double-sided tape. DETAILED DESCRIPTION

[0028] The aspects of the present invention can also be identified by the following structures and features.

[0029] The battery pack according to another aspect of the present invention is further provided with a double-sided tape for adhering the label to the outer casing and fixing it at a position to block the vent hole, and the fracture starting point is formed to be included in the area of ​​the label to which the double-sided tape is affixed. According to the above structure, the vent hole is sealed with the double-sided tape, which makes it easy to achieve waterproofness and airtightness, and by setting the fracture starting point in the area to which the double-sided tape is affixed, it is possible to maintain waterproofness and airtightness.

[0030] In a battery pack according to another aspect of the present invention, in any of the above aspects, the double-sided tape has a tape-side breaking portion formed at a position corresponding to the breaking starting point of the label.

[0031] Furthermore, in a battery pack according to another aspect of the present invention, in any of the above aspects, the rupture starting point is formed in a slit shape.

[0032] Furthermore, in a battery pack according to another aspect of the present invention, in any of the above aspects, the rupture starting point is provided at a plurality of locations on the label.

[0033] Furthermore, in another embodiment of the present invention, in any of the above embodiments, a portion of a label sticking area of ​​the outer shell where the label is stuck on the periphery of the exhaust hole has a narrow width portion whose bonding width is narrower than other portions, the narrow width portion has a deformation portion whose bonding width is different from the periphery of the exhaust hole, and the fracture starting point portion is arranged at a portion of the label adjacent to the deformation portion.

[0034] Hereinafter, the embodiments of the present invention will be described based on the accompanying drawings. However, the embodiments shown below are examples for concretizing the technical ideas of the present invention, and the present invention is not limited to the following methods. In addition, this specification does not limit the components shown in the claims to the components of the embodiments. In particular, the size, material, shape, relative configuration, etc. of the structural parts described in the embodiments are not intended to limit the scope of the present invention to this, as long as there is no particularly specific description, but are simply illustrative examples. In addition, the size, positional relationship, etc. of the components shown in the drawings are sometimes exaggerated for clear description. Further, in the following description, for the same name, symbol, representing the same or homogeneous components, detailed description is appropriately omitted. Further, the elements constituting the present invention can be set to constitute multiple elements with the same components to use a component to serve multiple elements, or it can be realized by sharing the function of a component with multiple components on the contrary.

[0035] The battery pack of the present invention can be used as a driving power source for vehicles such as electric carts for express delivery and golf courses, electric scooters, construction equipment, hybrid vehicles, and electric vehicles. In addition to the driving power source for power-assisted bicycles, it can also be used as a power source for portable electrical equipment such as wireless devices, electric cleaners, and electric tools. Or it can also be used as a backup power source for servers, a power supply device for home use, office use, and factory use in fixed power storage applications. Below, as one embodiment of the present invention, a battery pack used as a driving power source for an electric cart is described.

[0036] [Implementation Method 1]

[0037] The battery pack 100 according to the first embodiment of the present invention is shown in FIG. Figure 1 to Figure 7 In these figures, Figure 1 A perspective view showing a battery pack 100 according to Embodiment 1 is shown. Figure 2 Shows the representation Figure 1 An exploded perspective view of the surface of the battery pack 100, Figure 3 Shows the representation Figure 1 An exploded perspective view of the interior of the battery pack 100, Figure 4 Show Figure 1 The cross-sectional stereogram at line IV-IV is Figure 5 Show Figure 4 An enlarged cross-sectional view of the main parts, Figure 6 Shown as viewed from below Figure 2 The enlarged exploded perspective view of Figure 7 Show Figure 6 2 is an exploded perspective view of a label 20. The battery pack 100 shown in these figures includes an outer case 10, a label 20, and one or more secondary battery cells 1.

[0038] (External casing 10)

[0039] The outer casing 10 accommodates one or more secondary battery cells 1 and a battery holder 2. Figure 1 , Figure 2 As shown in FIG. 1 and FIG. 2 , the outer casing 10 is formed into a box shape. The outer casing 10 is divided into an upper casing 11 and a lower casing 12. The outer casing 10 is preferably made of a member with excellent insulation properties, such as a resin such as polycarbonate or PC-ABS alloy, but may also be made of a metal member such as aluminum or aluminum alloy. Figure 2 As shown, a holder accommodation space for accommodating the battery holder 2 is provided inside the outer casing 10 .

[0040] (Secondary battery cell 1)

[0041] One or more secondary battery cells 1 can use secondary battery cells whose outer cans are square or cylindrical. Figure 3 , Figure 4 In the example shown, 120 cylindrical secondary battery cells 1 are arranged in a longitudinal position. In addition, the secondary battery cells 1 are connected in series with 10 and in parallel with 12. In addition, the number, configuration, number of connections in series or in parallel, etc. of the secondary battery cells are not limited to this example, and any number and configuration can be used. Each secondary battery cell 1 has a positive and negative electrode. The positive and negative electrodes are preferably provided on one end face of the secondary battery cell 1. For such a secondary battery cell 1, known secondary batteries such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries can be appropriately utilized.

[0042] In addition, a safety valve is provided in the outer can of the secondary battery cell 1. The safety valve opens in response to an increase in the internal pressure of the outer can, and releases the gas inside the outer can to the outside.

[0043] (Exhaust hole 13)

[0044] On the other hand, Figure 2 , Figure 4 , Figure 5 As shown, the outer shell 10 has a vent hole 13 formed in a portion, and the vent hole 13 is used to release the high-pressure gas to the outside when the safety valve of the secondary battery cell 1 opens and discharges the high-pressure gas. Here, the vent hole 13 is formed in the label pasting area 14 where the label 20 is pasted, and the vent hole 13 is blocked by pasting the label 20. The vent hole 13 is set offset to one side of the upper surface of the outer shell 10. In addition, the vent hole 13 is not limited to being set on the upper surface of the outer shell, and can also be set on the side surface, bottom surface, etc. In addition, the vent hole can also be opened in multiple locations. The vent hole 13 is designed according to the volume of the outer shell 10, the battery capacity of the secondary battery cell 1, etc., for example, the width is set to 12 mm.

[0045] (Tag 20)

[0046] The label 20 is adhered to the periphery of the exhaust hole 13 of the outer shell 10 and is pasted to the label pasting area 14 of the outer shell 10. The label pasting area 14 is formed in a step portion 15 that is one layer lower than other areas of the outer shell 10 so as to be almost coplanar with the surface of the label 20. The label 20 is pre-printed with specifications of the battery pack 100, such as model number, manufacturer name, battery capacity, rated value and other information. The label 20 is made of a resin such as polycarbonate, polypropylene, or a member in which a paper base is impregnated or coated with a resin. The label 20 has a rectangular shape. Figure 2 In the examples of FIG. 1 and FIG. 2 , the label 20 is formed into a horizontally long rectangular shape with chamfered corners. However, the shape is not limited to this shape and may be formed into a vertically long, square, octagonal or other polygonal shape.

[0047] (Double-sided tape 30)

[0048] In addition, in order to attach the label 20, at least part of the back side of the label 20 has an attachment surface. Figure 6 , Figure 7 As shown, a double-sided tape 30 is attached around the label 20, and an attachment surface is attached to the label 20. The double-sided tape 30 is a member for fixing the label 20 at a position to block the exhaust hole 13. For example, the thickness of the label 20 is set to 0.5 mm, and the thickness of the double-sided tape 30 is set to 0.2 mm. In addition, the double-sided tape 30 is not limited to the double-sided tape 30, and an adhesive or the like may be used for bonding the label 20.

[0049] (fracture starting point 22)

[0050] In addition, the label 20 is provided with a rupture starting point 22 at a part of the bonding surface with the outer casing 10. By providing the rupture starting point 22 at a part of the label 20, even if high-pressure gas is released from the safety valve of the secondary battery cell 1 into the outer casing 10, the label 20 can be ruptured from the part whose strength is intentionally weakened by the rupture starting point 22 of the label 20, and the discharge position of the high-pressure gas can be accurately controlled, thereby improving safety. Figure 8A to Figure 8B This situation will be described with reference to a battery pack 800 according to a comparative example shown in FIG. 8. The battery pack 800 shown in these figures shows a situation in which a vent hole 813 of an outer casing 810 is sealed with a label 820. Inside the battery pack 800, when the safety valve of the secondary battery cell is open and Fig. 8A When the internal pressure of the shell increases, Figure 8B As shown, the label 820 is broken by the pressure, and the high-pressure gas is discharged to the outside of the housing from the exhaust hole 813. However, in this structure, it is difficult to balance the adhesive strength of the label 820 and the exhaust pressure. In addition, due to the deviation of the adhesive strength, it is difficult to control the exhaust direction.

[0051] In contrast, in the battery pack 100 according to the present embodiment, Fig. 9A as well as Fig. 9B As shown, by intentionally providing a fracture structure in the label 20, exhaust can be performed without depending on the adhesive strength of the label 20. That is, since exhaust can be performed from the location where the fracture starting point 22 is provided, it is easy to control the exhaust direction of the high-pressure gas.

[0052] For example, in an electrical device such as an electric cart that is used by a user by direct contact, in the event that a high-temperature and high-pressure gas is released to the outside, it is necessary to protect the human body from such a gas. To this end, by providing a structure that can pre-control the gas discharge position, as in the battery pack 100 involved in the present embodiment, it is easy to take safety measures. For example, in an electric scooter, a structure is generally adopted in which the battery pack is accommodated inside the base where the user sits. In this case, a protective wall can be provided at the gas release position so that the user does not directly contact the high-pressure gas. In this case, even if the entire surface of the battery pack is not covered with a protective wall, it is sufficient to partially provide a protective wall centered on the part where the gas is discharged in the discharge hole. In addition, by making the gas discharge direction easy to control, it is possible to further achieve the construction of safety measures and improve safety.

[0053] like Figure 4 , Figure 5As shown, the fracture starting point 22 is preferably formed to be included in the area of ​​the label 20 to which the double-sided tape 30 is attached. Thus, the vent 13 is sealed with the double-sided tape 30, and it is easy to exert waterproofness and airtightness, and by setting the fracture starting point 22 in the area to which the double-sided tape 30 is attached, the fracture starting point 22 can be formed and waterproofness and airtightness can be maintained.

[0054] In addition, if Figure 6 , Figure 7 As shown, the double-sided tape 30 preferably forms a tape-side break portion 32 at a position corresponding to the break starting point 22 of the label 20. This makes it easy to control the break starting point position of the double-sided tape 30. Preferably, the break starting point 22 is formed by a Thomson knife while the double-sided tape 30 is attached to the label 20.

[0055] The fracture starting point portion 22 is preferably formed in a slit shape. Thus, a slit-shaped fracture starting point portion 22 can be easily formed on the label 20 or the double-sided tape 30, and a starting point that is easy to break can be attached at an arbitrary position. In addition to being a straight line, the slit can also include a curve. In addition, the fracture starting point portion 22 is not limited to a slit, and can also be set in a point shape. Furthermore, a plurality of fracture starting points can also be provided. For example, a plurality of points can also be formed as the fracture starting point portion. In addition, the fracture starting points can also be formed at different positions of the label.

[0056] The label pasting area 14 of the label 20 pasted on the periphery of the exhaust hole 13 of the outer casing 10 has a narrow width portion in which the bonding width is narrower than other portions. The narrow width portion has a step portion 15 with a different bonding width from the periphery of the exhaust hole 13. The fracture starting point portion 22 is preferably provided based on the portion of the label 20 where stress is increased due to the high-pressure gas discharged by opening the safety valve of the secondary battery cell 1 by the step portion 15.

[0057] In addition, the rupture starting point 22 does not necessarily need to penetrate the label 20, and may be set in a so-called half-cut manner only on the surface of the label 20 without penetrating. In addition, if the tape side rupture portion 32 of the double-sided tape 30 is at a level that does not affect the rupture starting point due to the material and strength of the double-sided tape 30, it may be set as Fig.10 As in the label 20' shown in the modified example of FIG. 1 , only the breaking starting point 22' is provided, and no tape-side breaking portion is formed in the double-sided tape 30'.

[0058] The position of the fracture starting point 22 is preferably designed according to the shape of the area where the label 20 is bonded. That is, by setting it at a location where stress is likely to concentrate on the bonding surface of the label 20, it is possible to more accurately determine the position. For example, in the example of using a double-sided tape 30 for bonding the label 20, the stress generated in the discharge hole blocked by the label 20 is analyzed based on the pattern of the double-sided tape 30 through a CAE-based simulation, and the position and size of the fracture starting point 22 can be designed based on the analysis results. The pattern of the double-sided tape 30 of the battery pack 100 involved in the above-mentioned embodiment 1, the results of the stress analysis based on CAE, and the shape of the slit are respectively shown in FIG. Fig.11A , Fig. 11B , Fig. 11C Here, for easy viewing, the pattern of the battery pack 100 is shown in a top view. That is, the pattern of the double-sided tape 30 formed on the back side of the label 20 is shown when viewed from the front side. Fig.11A In the case where the pattern of the double-sided tape 30 is formed around the label 20 in an equal width manner as shown in FIG. Fig. 11B As shown in FIG. 1 , the stress is concentrated in the middle part of the long side, so the fracture starting point 22 is preferably as shown in FIG. Fig. 11C The illustrated embodiment is disposed on one of the long sides of the label 20 .

[0059] [Embodiments 2 to 5]

[0060] Here, stress analysis based on CAE is performed according to different patterns of double-sided tape, and examples of designing the fracture starting point based on the stress analysis are shown as battery packs according to embodiments 2 to 5. Figures 12A to 15C .like Fig. 12B , Fig. 13B , Fig. 14B , Fig. 15B As shown, according to the stress analysis results of CAE, it is determined that in the rectangular discharge hole, the label 20 is deformed by the high pressure in the battery pack 100, and the central part of the long side is deformed the most and the stress is increased. On the contrary, it is determined that the corners of the label 20 have a lower influence of pressure as the distance increases.

[0061] For example, in the battery pack according to the second embodiment, Fig. 12A As shown in FIG. 1 , the central portion of the long side of the double-sided tape 30B is set to have a narrow width. According to the stress analysis results, as shown in FIG. Fig. 12B As shown in FIG. 1 , the corner of the narrowed region has a local stress increase, so the slit of the fracture starting point portion 22B provided in the label 20B is as shown in FIG. Fig. 12C As shown, it is provided adjacent to the narrow-width deformation portion 24B at the center of the long side.

[0062] In addition, in the battery pack according to the third embodiment, if Fig.13A As shown in FIG. 1 , one of the corners of the double-sided tape 30C is set as a partially narrow deformation portion 24C. According to the stress analysis results, as shown in FIG. Fig. 13B As shown in FIG. 1 , the stress increases along the long side toward the deformed portion 24C whose width becomes narrower, so the slit of the fracture starting point portion 22C provided in the label 20C is as shown in FIG. Fig. 13C As shown, the deformed portion 24C is extended from the center of the long side to the corner, and is further bent in front of the deformed portion 24C.

[0063] Furthermore, in the battery pack according to the fourth embodiment, Fig.14A As shown in FIG. 1 , a U-shaped tapered deformed portion 24D is formed in the middle of the long side of the double-sided tape 30D toward the inside, and the width of the double-sided tape 30D in the deformed portion 24D is narrowed. Such a shape can be produced when the shape of the exhaust hole 13 is partially narrowed due to the restriction on the outer shell 10 side. According to the stress analysis results, as shown in FIG. Fig. 14B As shown in FIG. 1 , stress increases on both sides of the U-shaped deformation portion 24D of the long side, so the slit of the fracture starting point portion 22D provided in the tag 20D is as shown in FIG. Fig. 14C As shown, both sides of the U-shaped deformation portion 24D along the center of the long side are extended.

[0064] Furthermore, in the battery pack according to the fifth embodiment, Fig.15A As shown, in the middle of the long side of the double-sided tape 30E, as shown in FIG. Fig. 12A The double-sided tape 30E is narrowed by forming a deformed portion 24E that is recessed from the inside, and on the left and right sides, the width is narrowed by recessing from the outside, so that the lower side of the annular double-sided tape 30E is narrower than the other sides. Fig. 15B As shown in FIG. 1 , in the deformation portion 24E in the middle of the long side, the stress increases, so the slit of the fracture starting point portion 22E provided in the label 20E is as shown in FIG. Fig. 15C As shown, the deformation part 24E is provided in a curved manner at the boundary between the central narrowing part and the left and right narrowing parts of the long side.

[0065] In the above example, the battery pack is mounted on the electrical device to be driven, and power is supplied to the electrical device. In addition, in the case where the remaining capacity of the battery pack decreases or the battery pack deteriorates over the years, the battery pack can be replaced and the electrical device can continue to be used. However, the present invention is not limited to a replaceable battery pack in which the battery pack mainly accommodates secondary battery cells, but can also be applied to a method in which secondary battery cells are accommodated in the frame of the electrical device. In the present disclosure, it is sufficient for the battery pack to be able to accommodate secondary battery cells in the shell, and a structure in which a secondary battery cell for driving is built into the frame of the electrical device itself is called a battery pack. That is, the present invention is not limited to replaceable battery packs, but can also be applied to electrical devices with built-in secondary battery cells.

[0066] Industrial Applicability

[0067] The battery pack of the present invention can be suitably used as a power source for a wireless device, a power source for portable electrical equipment such as an electric cleaner and an electric tool, and can also be suitably used as a power source device for a mobile body such as an assist bicycle and an electric cart.

[0068] Explanation of symbols

[0069] 100…Battery pack

[0070] 1…Secondary battery cell

[0071] 2…Battery holder

[0072] 10…External housing

[0073] 11…Upper housing

[0074] 12…Lower housing

[0075] 13…Exhaust hole

[0076] 14…Label pasting area

[0077] 15…Level difference

[0078] 20, 20', 20B, 20C, 20D, 20E... Labels

[0079] 22, 22', 22B, 22C, 22D, 22E...fracture starting point

[0080] 24B, 24C, 24D, 24E…deformation part

[0081] 30, 30', 30B, 30C, 30D, 30E...double-sided tape

[0082] 32…Tear part on the tape side

[0083] 800…Battery pack

[0084] 810…External housing

[0085] 813…Exhaust hole

[0086] 820… tag.

Claims

1. A battery pack comprising: One or more secondary battery cells, with a safety valve provided on the outer can; an outer casing that accommodates the one or more secondary battery cells and has a vent hole formed in a portion thereof for releasing high-pressure gas to the outside when a safety valve of the secondary battery cell opens and discharges the high-pressure gas; and The label is adhered to the periphery of the exhaust hole of the outer shell to block the exhaust hole. The label has a breaking starting point at a portion of a surface that is bonded to the outer casing.

2. The battery pack according to claim 1, wherein: The battery pack further comprises: Double-sided tape, used to adhere the label to the outer shell and fix it at the position of blocking the exhaust hole, The rupture starting point is formed so as to be included in a region of the label to which the double-sided tape is attached.

3. The battery pack according to claim 2, wherein: The double-sided tape has a tape-side breaking portion formed at a position corresponding to the breaking starting point of the label.

4. The battery pack according to any one of claims 1 to 3, wherein: The fracture starting point is formed in a slit shape.

5. The battery pack according to any one of claims 1 to 3, wherein: The breaking starting points are arranged at a plurality of locations of the label.

6. The battery pack according to any one of claims 1 to 3, wherein: The label sticking area of ​​the peripheral edge of the exhaust hole of the outer casing to which the label is stuck has a narrow width portion in a part thereof, wherein the bonding width is narrower than that of other portions. The narrow width portion has a deformed portion having a different bonding width from the periphery of the exhaust hole, The rupture starting point is provided at a portion of the label adjacent to the deformation portion.

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