Battery pack

Abstract

The utility model relates to the technical field of batteries, and discloses a battery pack and box body structure which comprises a beam body assembly, a bottom plate and a first phase change medium, the beam body assembly is arranged on the bottom plate and encircles a mounting space; an exhaust channel is arranged in the beam body assembly, an exhaust hole is formed in the wall face, corresponding to the mounting space, of the beam body assembly, an air leakage hole is formed in the outer wall face of the beam body assembly, and the exhaust channel communicates with the exhaust hole and the air leakage hole; after the box body structure and related parts such as the battery cells are assembled into the battery pack, smoke enters the exhaust channel through the exhaust holes when the battery cells are subjected to thermal runaway, and the first phase change medium absorbs heat quickly and is subjected to phase change after being in contact with the smoke with higher temperature, so that the temperature of the smoke is effectively reduced, and the service life of the battery pack is prolonged. In addition, the temperature of the flue gas exhausted by the box body structure can be reduced, the exhausted flue gas is prevented from igniting other objects, and the possibility of secondary damage is reduced.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to battery packs. Background Technology

[0002] With the continuous development of new energy vehicle technology, the requirements for its safety are also constantly increasing. As a key component of new energy vehicles, the research and development of power batteries is also ongoing. Power batteries are at risk of thermal runaway under conditions such as overcharging, over-discharging, internal short circuits, or external impacts. As the internal temperature of the battery rises rapidly, it can easily trigger a chain reaction that endangers personal and property safety.

[0003] Currently, when a cell in a power battery experiences thermal runaway, it will generate a large amount of high-temperature fumes. During the emission of these fumes to the outside of the battery, the relatively enclosed space inside the casing allows the high-temperature fumes to easily transfer heat to adjacent components, causing the internal temperature of the casing to rise rapidly. This can easily lead to heat spread and cause thermal runaway of the entire power battery, potentially triggering a vehicle accident quickly and posing a significant safety hazard. Utility Model Content

[0004] In view of this, the present invention provides a battery pack to solve the problem of poor safety of existing power batteries after thermal runaway.

[0005] In a first aspect, this utility model provides a box structure, including: a beam assembly, a base plate, and a first phase change medium; the beam assembly is disposed on the base plate and together with the base plate forms an installation space, the installation space being used to install battery cells; an exhaust channel is provided inside the beam assembly, an exhaust hole is provided on the wall of the beam assembly corresponding to the installation space, and a vent hole is provided on the outer wall of the beam assembly, the exhaust channel being connected to the exhaust hole and the vent hole respectively; the first phase change medium is disposed in the exhaust channel.

[0006] Beneficial effects: By installing a first phase change medium in the exhaust channel, and assembling the battery pack with the housing structure and related components such as the battery cells, when thermal runaway occurs in the battery cells installed in the housing structure, the flue gas generated by the battery cells will enter the exhaust channel through the exhaust port. As the flue gas moves along the exhaust channel towards the vent, the first phase change medium, upon contact with the high-temperature flue gas, will rapidly absorb heat and undergo a phase change, thereby quickly and effectively reducing the temperature of the flue gas. This prevents a large amount of heat from accumulating in the installation space, which would cause the battery pack temperature to rise rapidly. This not only promptly stops or slows down the rate of heat spread inside the battery pack, providing more time for emergency response and rapid escape, but also reduces the temperature of the flue gas discharged from the housing structure, preventing excessively high flue gas temperatures from igniting other objects and reducing the possibility of secondary damage from the flue gas. This effectively solves the problem of poor safety after thermal runaway of existing power batteries.

[0007] In one alternative embodiment, the box structure further includes a guide assembly disposed on the wall of the mounting space corresponding to the beam assembly and located below the vent hole, the guide assembly having an inclined guide surface.

[0008] Beneficial effects: The guiding surface of the guiding component can guide the flue gas to the exhaust port, improving the efficiency and reliability of the flue gas entering the exhaust channel.

[0009] In one alternative embodiment, the guiding component includes a guiding plate and a second phase change medium. The guiding plate is connected to the wall of the beam assembly and has a guiding surface, on which the second phase change medium is laid.

[0010] Beneficial effects: While the guiding component guides the flue gas, the second phase change medium absorbs heat during phase change when it comes into contact with the high-temperature flue gas. This type of guiding component can cool the flue gas before it enters the exhaust channel.

[0011] In one alternative embodiment, the box structure further includes a first barrier layer disposed on the wall of the corresponding installation space of the beam assembly and used to block the vent holes.

[0012] Beneficial effects: The first barrier layer can effectively seal the vent hole without thermal runaway of the cell, and can effectively prevent the air in the installation space from contacting the first phase change medium in advance, thus preventing the first phase change medium from undergoing a phase change and failing prematurely.

[0013] In one alternative embodiment, the beam assembly has a partition inside, and at least a portion of the space in the exhaust channel is divided by the partition to form multiple exhaust chambers. The partition has a connecting hole for connecting adjacent exhaust chambers, and a first phase change medium is laid on the inner wall of the exhaust chamber.

[0014] Beneficial effects: Setting up baffles can effectively increase the area of ​​the inner wall of the exhaust channel. Compared with an exhaust channel with only a single cavity, it can effectively increase the total amount of the first phase change medium and also increase the contact area of ​​the first phase change medium with the flue gas.

[0015] In one optional embodiment, the beam assembly includes a first beam and a plurality of second beams, the first beam extending along a first direction, the second beams extending along a second direction, the plurality of second beams being spaced apart along the first direction, the first beam being connected to the plurality of second beams simultaneously, an exhaust port being disposed on the second beams, and a venting port being disposed on the first beam.

[0016] Beneficial effects: In this type of beam assembly, after the flue gas enters the second beam, it needs to move continuously along the exhaust channel inside the second beam to the first beam before it can be discharged outward through the vent. This can effectively increase the length of the flue gas discharge path and allow the flue gas to fully exchange heat with the first phase change medium in the exhaust channel, thereby improving the cooling effect and the reliability of the flue gas temperature reduction process.

[0017] In one alternative embodiment, a second barrier layer is provided between the exhaust channel of the second beam and the exhaust channel of the first beam. The second barrier layer has a connecting opening and a baffle disposed in the connecting opening. The baffle is a weak area pre-formed on the second barrier layer.

[0018] Beneficial effects: Since the flue gas will first enter the interior of the second beam, the second baffle layer can be set up to allow the flue gas to fully exchange heat in the second beam before it breaks through the baffle and enters the first beam, thus ensuring the cooling effect of the flue gas.

[0019] In one optional embodiment, each second beam is provided with a plurality of vent holes, and the vent holes on each second beam are spaced apart along a second direction; and / or, the vent holes are provided with a first explosion-proof valve.

[0020] Beneficial effects: With a large number of exhaust holes, the flue gas in the installation space can enter the exhaust channel more quickly and directly, ensuring the exhaust effect. The first explosion-proof valve can prevent external gas from entering the exhaust channel through the vent hole, prevent the first phase change medium from undergoing a phase change prematurely and failing, and improve the working reliability of the first phase change medium.

[0021] In one alternative implementation, the battery pack also includes a plurality of battery cells stacked in the mounting space.

[0022] In one alternative embodiment, the battery cell has a second explosion-proof valve located at one end of the battery cell facing the beam assembly, and the second explosion-proof valve is configured to correspond to the vent hole of the housing structure.

[0023] Beneficial effect: This type of device with a second explosion-proof valve allows the gas emitted during thermal runaway of the battery cell to directly enter the exhaust channel. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1This is a three-dimensional schematic diagram of a box structure according to an embodiment of the present utility model;

[0026] Figure 2 for Figure 1 The box structure shown is not a three-dimensional schematic diagram of some beam components;

[0027] Figure 3 for Figure 1 The diagram shows a three-dimensional representation of the enclosure structure and the assembled battery cells.

[0028] Figure 4 for Figure 3 A three-dimensional schematic diagram of the box structure after it has been cut open;

[0029] Figure 5 for Figure 4 A partially enlarged schematic diagram of the box structure shown;

[0030] Figure 6 for Figure 4 The diagram shown is a partially enlarged view of the box structure without the first barrier layer.

[0031] Figure 7 for Figure 3 A three-dimensional schematic diagram of the box structure after it has been cut open;

[0032] Figure 8 for Figure 7 The diagram shown is a partially enlarged view of the enclosure structure without the battery cells shown.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Beam assembly; 101. Exhaust channel; 102. Exhaust port; 103. Vent hole; 104. Partition plate; 1041. Connecting hole; 105. Exhaust chamber; 106. First beam; 107. Second beam; 108. First explosion-proof valve;

[0035] 2. Base plate; 3. First phase change medium; 4. Installation space;

[0036] 5. Guiding component; 501. Guiding plate; 502. Second phase change medium;

[0037] 6. First barrier layer; 7. Second barrier layer; 701. Baffle plate; 8. Battery cell; 801. Second explosion-proof valve;

[0038] X, first direction; Y, second direction; Z, third direction. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0040] The following is combined with Figures 1 to 8 The following describes embodiments of the present invention.

[0041] According to an embodiment of the present invention, a battery pack is provided, particularly an innovative design for the battery pack's casing structure, comprising: a beam assembly 1, a base plate 2, and a first phase change medium 3; the beam assembly 1 is disposed on the base plate 2 and together with the base plate 2 forms an installation space 4, the installation space 4 being used to install battery cells 8; an exhaust channel 101 is provided inside the beam assembly 1, an exhaust hole 102 is provided on the wall of the beam assembly 1 corresponding to the installation space 4, and a vent hole 103 is provided on the outer wall of the beam assembly 1, the exhaust channel 101 being connected to the exhaust hole 102 and the vent hole 103 respectively; the first phase change medium 3 is disposed in the exhaust channel 101.

[0042] By applying the housing structure of this embodiment, a first phase change medium 3 is set in the exhaust channel. After the housing structure and related components such as the battery cell 8 are assembled into a battery pack, when the battery cell 8 installed in the housing structure experiences thermal runaway, the flue gas generated by the battery cell 8 will enter the exhaust channel 101 through the exhaust port 102. When the flue gas moves along the exhaust channel 101 towards the vent 103, the first phase change medium 3 will rapidly absorb heat and undergo a phase change after contacting the high-temperature flue gas. This can quickly and effectively reduce the temperature of the flue gas, preventing a large amount of heat from accumulating in the installation space 4 and causing the temperature of the battery pack to rise rapidly. This can both stop or delay the rate of heat spread inside the battery pack in time, giving more time for emergency handling and rapid escape, and also reduce the temperature of the flue gas discharged from the housing structure, preventing the flue gas temperature from being too high and igniting other objects, reducing the possibility of secondary damage from the flue gas. This effectively solves the problem of poor safety after thermal runaway of existing power batteries.

[0043] In addition, since the beam assembly 1 is provided with an exhaust channel 101, which is an additional space outside the installation space 4, the exhaust channel 101 also has the function of reducing the flue gas pressure generated by the battery cell 8.

[0044] It should be noted that the phase change process of the first phase change medium 3 is not limited, and can be either solid to liquid or solid to gas. In addition, the specific type of the first phase change medium 3 is not limited, and can refer to existing types of media that can absorb heat through phase change. Its constituent substances can be one or more of the following: crystalline hydrated salts, molten salts, metals or alloys, paraffin, acetic acid, and other organic substances.

[0045] Preferably, the first phase change medium 3 is composed of chlorinated paraffin, borax decahydrate, graphite, silicon dioxide, glyceryl monostearate, sodium chloride, superabsorbent resin, sodium sulfate decahydrate, sodium ammonium nitrate acetate, ammonium sulfate, sodium bisulfate, gelatin, and carbon fiber.

[0046] In one possible implementation, the housing structure further includes a guide component 5, which is disposed on the wall of the beam assembly 1 corresponding to the installation space 4 and located below the exhaust port 102. The guide component 5 has an inclined guide surface, which can guide the flue gas to the exhaust port 102, thereby improving the reliability of the efficiency of the flue gas entering the exhaust channel 101.

[0047] It should be noted that "below" of the exhaust port 102 refers to the direction of the exhaust port 102 closer to the base plate 2.

[0048] Specifically, there is no limitation on the specific form of the guiding surface. It can be an inclined plane or an inclined curved surface, as long as it can guide the flue gas below the exhaust port 102 into the exhaust port 102.

[0049] In addition, there are no restrictions on the specific form and connection method of the guide component 5. The guide component 5 can be a plate structure or a block structure. The guide component 5 can also be connected to the beam component 1 by welding or by bonding. The choice can be made flexibly according to the requirements.

[0050] In one possible implementation, the guiding component 5 includes a guiding plate 501 and a second phase change medium 502. The guiding plate 501 is connected to the wall of the beam assembly 1 and has a guiding surface. The second phase change medium 502 is laid on the guiding surface. While the guiding component 5 guides the flue gas, the second phase change medium 502 absorbs heat through a phase change when it comes into contact with the high-temperature flue gas. This type of guiding component 5 can cool the flue gas before it enters the exhaust channel 101. In addition, since the guiding component 5 is located in the installation space 4, it can come into more direct contact with the flue gas, thus reducing the temperature in the installation space 4 more effectively and quickly, preventing the remaining battery cells 8 from burning out.

[0051] It should be noted that the phase change process of the second phase change medium 502 is not limited, and can be either solid-to-liquid or solid-to-gas. In addition, the specific type of the second phase change medium 502 is not limited, and can refer to existing types of media capable of phase change and heat absorption. Its constituent substances can be one or more of the following: crystalline hydrated salts, molten salts, metals or alloys, paraffin, acetic acid, and other organic substances.

[0052] Preferably, the second phase change medium 502 is composed of chlorinated paraffin, borax decahydrate, graphite, silicon dioxide, glyceryl monostearate, sodium chloride, superabsorbent resin, sodium sulfate decahydrate, sodium ammonium nitrate acetate, ammonium sulfate, sodium bisulfate, gelatin, and carbon fiber.

[0053] Specifically, such as Figure 6 As shown, the guide plate 501 and the second phase change medium 502 both extend along the second direction. The guide plate 501 includes a guide section and connecting sections disposed at both ends of the guide section. The included angle between the guide section and the base plate 2 is in the range of 45 degrees to 75 degrees. One end of the guide section is bonded to the wall of the beam assembly 1 through the connecting section, and the other end is connected to the base plate 2 or a component above the base plate 2 through the connecting section.

[0054] In one possible implementation, such as Figure 5 As shown, the box structure also includes a first barrier layer 6. The first barrier layer 6 is disposed on the wall of the beam assembly 1 corresponding to the installation space 4 and is used to block the exhaust port 102. The first barrier layer 6 can effectively block the exhaust port 102 when the battery cell 8 has not experienced thermal runaway. It can effectively prevent the air in the installation space 4 from contacting the first phase change medium 3 in advance, and prevent the first phase change medium 3 from undergoing a phase change and failing in advance. In addition, when the exhaust port 102 near the thermal runaway battery cell 8 is blown open, the first barrier layer 6 can prevent the flue gas entering the exhaust channel 101 from re-entering the installation space 4 through other exhaust ports 102, thereby improving the reliability of the exhaust process.

[0055] Specifically, there is no limitation on the specific type and structure of the first blocking layer 6. A first blocking layer 6 can be set separately for each exhaust hole 102, or multiple exhaust holes 102 can be blocked by a first blocking layer 6. The choice is flexible.

[0056] Preferably, the first barrier layer 6 is an elastic diaphragm. Since the battery pack also generates heat during normal operation, the gas volume in the installation space 4 will also change with temperature fluctuations. The elastic first barrier layer 6 can reliably seal the exhaust port 102 under such conditions.

[0057] The first barrier layer 6 can be damaged or melted by the high-temperature jet emitted when the battery cell 8 thermally runs away, thereby allowing the subsequent high-temperature gas to enter the exhaust channel 101.

[0058] In one possible implementation, such as Figure 5 and Figure 6 As shown, the beam assembly 1 has a partition 104 inside. At least a portion of the space in the exhaust channel 101 is divided by the partition 104 to form multiple exhaust chambers 105. The partition 104 has a connecting hole 1041 for connecting adjacent exhaust chambers 105. The first phase change medium 3 is laid on the inner wall of the exhaust chamber 105. The partition 104 can effectively increase the area of ​​the inner wall of the exhaust channel 101. Compared with an exhaust channel 101 with only a single chamber, it can effectively increase the total amount of the first phase change medium 3 and also increase the contact area of ​​the first phase change medium 3 that can contact the flue gas.

[0059] Correspondingly, in order to prevent the first phase change medium 3 from blocking the connecting hole 1041, the first phase change medium 3 is provided with a vent hole at the position corresponding to the connecting hole 1041.

[0060] Specifically, there is no limitation on the number and direction of the partitions 104. There can be one or more, and they can be set at intervals along the first direction X, the second direction Y, or the third direction Z.

[0061] In addition, there is no limitation on the number and size of the connecting holes 1041 on the partition 104. They can be square holes, round holes, or strip holes, etc. There can be one or more connecting holes 1041, which can be flexibly selected.

[0062] Preferably, such as Figure 5 and Figure 6 As shown, two partitions 104 are spaced apart along the third direction Z, dividing the exhaust passage 101 into three exhaust chambers 105 spaced apart along the third direction Z.

[0063] Furthermore, beam assembly 1 is an aluminum profile extrusion molding component, and the first phase change medium 3 is bonded to the inner wall of beam assembly 1.

[0064] In one possible implementation, the beam assembly 1 includes a first beam 106 and a plurality of second beams 107. The first beam 106 extends along a first direction X, and the second beams 107 extend along a second direction Y. The plurality of second beams 107 are spaced apart along the first direction X. The first beam 106 is connected to the plurality of second beams 107. An exhaust port 102 is disposed on the second beam 107, and a vent 103 is disposed on the first beam 106. In this type of beam assembly 1, after the flue gas enters the second beam 107, it needs to continuously move along the exhaust channel 101 inside the second beam 107 to the first beam 106 before it can be discharged outward through the vent 103. This can effectively increase the path length of the flue gas discharge and allow the flue gas to fully exchange heat with the first phase change medium 3 in the exhaust channel 101, thereby improving the cooling effect and the reliability of the flue gas temperature reduction process.

[0065] Among them, the first direction X, the second direction Y, and the third direction Z intersect each other in pairs.

[0066] Specifically, there is no limit to the number of second beams 107. There can be two second beams 107, or three or more second beams 107. A row of stacked battery cells 8 can be installed between two adjacent second beams 107. The specific number can be selected according to the requirements.

[0067] Furthermore, there are no restrictions on the number of partitions 104 and the number of exhaust cavities 105 formed in different second beams 107; they can be the same or different, and can be flexibly selected.

[0068] In one possible implementation, a second barrier layer 7 is provided between the exhaust passage 101 of the second beam 107 and the exhaust passage 101 of the first beam 106. The second barrier layer 7 has a connecting port and a baffle 701 disposed in the connecting port. The baffle 701 is a weak area pre-formed on the second barrier layer 7. Since the flue gas will first enter the interior of the second beam 107, the second barrier layer 7 allows the flue gas to fully exchange heat in the second beam 107 before breaking through the baffle 701 and entering the first beam 106, thus ensuring the cooling effect of the flue gas.

[0069] Specifically, such as Figure 8 As shown, the destructive pressure difference at baffle 701 ranges from 1.5 kPa to 3.5 kPa.

[0070] In one possible implementation, each second beam 107 is provided with multiple exhaust holes 102. The exhaust holes 102 on each second beam 107 are spaced apart along the second direction Y. With a large number of exhaust holes 102, the flue gas in the installation space 4 can enter the exhaust channel 101 more quickly and directly, ensuring the exhaust effect.

[0071] Specifically, such as Figure 1 As shown, multiple vent holes 102 on each second beam 107 are spaced apart along the second direction Y.

[0072] In one possible implementation, a first explosion-proof valve 108 is provided in the vent 103 to prevent external gas from entering the exhaust channel 101 through the vent 103, thereby preventing the first phase change medium 3 from undergoing a phase change prematurely and failing, and improving the reliability of the exhaust channel 101.

[0073] In one possible implementation, the battery pack also includes a plurality of battery cells 8, which are stacked in the mounting space 4.

[0074] In one possible implementation, the battery cell 8 has a second explosion-proof valve 801, which is located at one end of the battery cell 8 facing the beam assembly 1. The second explosion-proof valve 801 is correspondingly arranged with the exhaust port 102 of the housing structure. This arrangement of the second explosion-proof valve 801 allows the gas discharged when the battery cell 8 experiences thermal runaway to directly enter the exhaust channel 101.

[0075] like Figure 3 , Figure 4 as well as Figure 7 As shown, multiple battery cells 8 are stacked along the second direction Y. Among adjacent battery cells 8, the second explosion-proof valves 801 of the two battery cells 8 are located at different ends of their own first direction X. Each second explosion-proof valve 801 is arranged opposite to the exhaust port 102 on its side.

[0076] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery pack, characterized in that, The battery pack's housing structure includes: a beam assembly (1), a base plate (2), and a first phase change medium (3); The beam assembly (1) is disposed on the base plate (2) and together with the base plate (2) forms an installation space (4), the installation space (4) being used to install the battery cell (8); The beam assembly (1) has an exhaust channel (101) inside, an exhaust hole (102) is provided on the wall of the installation space (4) corresponding to the beam assembly (1), and an air vent (103) is provided on the outer wall of the beam assembly (1). The exhaust channel (101) is connected to the exhaust hole (102) and the air vent (103) respectively. The first phase change medium (3) is disposed in the exhaust channel (101).

2. The battery pack according to claim 1, characterized in that, The box structure also includes a guide component (5), which is disposed on the wall of the beam assembly (1) corresponding to the installation space (4) and located below the exhaust hole (102). The guide component (5) has an inclined guide surface.

3. The battery pack according to claim 2, characterized in that, The guiding component (5) includes a guiding plate (501) and a second phase change medium (502). The guiding plate (501) is connected to the wall of the beam component (1) and has the guiding surface. The second phase change medium (502) is laid on the guiding surface.

4. The battery pack according to any one of claims 1 to 3, characterized in that, The box structure also includes a first blocking layer (6), which is disposed on the wall of the beam assembly (1) corresponding to the installation space (4) and is used to block the exhaust hole (102).

5. The battery pack according to any one of claims 1 to 3, characterized in that, The beam assembly (1) is provided with a partition (104) inside. At least a portion of the space in the exhaust channel (101) is divided by the partition (104) to form a plurality of exhaust chambers (105). The partition (104) is provided with a connecting hole (1041) for connecting adjacent exhaust chambers (105). The first phase change medium (3) is laid on the inner wall of the exhaust chamber (105).

6. The battery pack according to claim 5, characterized in that, The beam assembly (1) includes a first beam (106) and a plurality of second beams (107). The first beam (106) extends along a first direction (X), and the second beams (107) extend along a second direction (Y). The plurality of second beams (107) are spaced apart along the first direction (X). The first beam (106) is connected to the plurality of second beams (107). The vent (102) is disposed on the second beam (107), and the vent (103) is disposed on the first beam (106).

7. The battery pack according to claim 6, characterized in that, A second barrier layer (7) is provided between the exhaust channel (101) of the second beam (107) and the exhaust channel (101) of the first beam (106). The second barrier layer (7) has a communication port and a baffle (701) disposed in the communication port. The baffle (701) is a weak area pre-formed on the second barrier layer (7).

8. The battery pack according to claim 6, characterized in that, Each of the second beams (107) is provided with a plurality of the exhaust holes (102), and the exhaust holes (102) on each of the second beams (107) are spaced apart along the second direction (Y); And / or, the vent hole (103) is provided with a first explosion-proof valve (108).

9. The battery pack according to any one of claims 1 to 3, characterized in that, Also includes: Multiple battery cells (8) are stacked in the mounting space (4).

10. The battery pack according to claim 9, characterized in that, The battery cell (8) has a second explosion-proof valve (801), which is located at one end of the battery cell (8) facing the beam assembly (1). The second explosion-proof valve (801) is correspondingly arranged with the vent hole (102) of the box structure.

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