Battery pack and breather valve for a battery pack

Abstract

The application relates to a battery pack and a breather valve for the battery pack, the battery pack comprising: a box body having an inner cavity; a battery module accommodated in the inner cavity; a breather valve mounted to the box body for selectively connecting or disconnecting the inner cavity with an external environment in gas phase; the breather valve comprising: an air passage comprising a first passage section and a second passage section, the second passage section being connected in series outside the first passage section; a desiccant arranged in the first passage section; a valve plate assembly arranged in the second passage section and configured to be in a closed state when the air pressure in the inner cavity is equal to the air pressure in the external environment, thereby cutting off the second passage section; and in an open state when the air pressure in the inner cavity is higher or lower than the air pressure in the external environment, thereby making the second passage section conductive.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy, in particular to a battery pack and a breather valve for the battery pack. BACKGROUND

[0002] A battery pack provided by the related art comprises a box body and a battery module accommodated in the box body. However, the battery pack may have a safety hazard caused by moisture. Specifically, when the temperature inside and outside the box body changes to cause moisture-containing air to enter the box body, condensate water may be generated in the box body due to the cooling system in the box body or due to temperature reduction. The condensate water may cause short circuit of the battery module and electronic components in the box body, thereby causing a safety problem. SUMMARY

[0003] In view of this, the present application provides a battery pack and a breather valve for the battery pack.

[0004] In a first aspect, the present application provides a battery pack, comprising:

[0005] a box body having an inner cavity;

[0006] a battery module accommodated in the inner cavity;

[0007] a breather valve mounted to the box body and configured to selectively connect or disconnect the inner cavity with an external environment in gas phase;

[0008] characterized in that the breather valve comprises:

[0009] an air passage comprising a first passage section and a second passage section, the second passage section being connected in series outside the first passage section;

[0010] a desiccant arranged in the first passage section;

[0011] a valve plate assembly arranged in the second passage section and configured to be in a closed state when the air pressure in the inner cavity is equal to the air pressure in the external environment, thereby cutting off the second passage section, and in an open state when the air pressure in the inner cavity is higher or lower than the air pressure in the external environment, thereby connecting the second passage section.

[0012] In some possible embodiments, the valve plate assembly comprises:

[0013] an elastically deformable first valve plate having a first air passage hole;

[0014] an elastically deformable second valve plate having a second air passage hole;

[0015] a partition plate arranged between the first valve piece and the second valve piece and having an inner side surface, an outer side surface opposite to the inner side surface, a third gas passage hole and a fourth gas passage hole penetrating from the inner side surface to the outer side surface and spaced apart from each other;

[0016] In an initial state, the first valve piece is pressed against the inner side surface and thereby blocks the fourth gas passage hole, the second valve piece is pressed against the outer side surface and thereby blocks the third gas passage hole, and the first gas passage hole is in communication with the third gas passage hole and the second gas passage hole is in communication with the fourth gas passage hole,

[0017] When the gas pressure in the inner cavity is lower than the gas pressure in the external environment, the first valve piece is elastically deformed towards the inner side under the action of the gas pressure, thereby forming a first air gap between the first valve piece and the inner side surface, thereby unblocking the fourth gas passage hole by the first valve piece and making the fourth gas passage hole in communication with the first gas passage hole via the first air gap,

[0018] When the gas pressure in the inner cavity is higher than the gas pressure in the external environment, the second valve piece is elastically deformed towards the outer side under the action of the gas pressure, thereby forming a second air gap between the second valve piece and the outer side surface, thereby unblocking the fourth gas passage hole by the second valve piece and making the third gas passage hole in communication with the second gas passage hole via the second air gap.

[0019] In some possible implementations, the first valve piece and the second valve piece are both made of silica gel.

[0020] In some possible implementations, the valve piece assembly further comprises:

[0021] a first pressing piece laminated on the inner side of the first valve piece and exerting a pressing force on the first valve piece towards the inner side surface;

[0022] a second pressing piece laminated on the outer side of the second valve piece and exerting a pressing force on the second valve piece towards the outer side surface.

[0023] In some possible implementations, the valve piece assembly further comprises:

[0024] a tensioning element penetrating through the first pressing piece, the first valve piece, the partition plate, the second valve piece and the second pressing piece and exerting a tensioning force for moving the first pressing piece and the second pressing piece towards each other in the inner-outer direction.

[0025] In some possible implementations, the first pressing piece has a plurality of first holes penetrating therethrough, and the second pressing piece has a plurality of second holes penetrating therethrough;

[0026] When viewed along a direction perpendicular to the partition plate, a portion of the first holes, a portion of the second holes, the first gas passage and the third gas passage overlap, another portion of the first holes, another portion of the second holes, the second gas passage and the fourth gas passage overlap, the third gas passage is completely covered by the second valve sheet, the fourth gas passage is completely covered by the first valve sheet, and each of the first gas passage and the third gas passage is spaced apart from each of the second gas passage and the fourth gas passage.

[0027] In some possible embodiments, the first valve sheet has a first protrusion protruding towards the outside, the first protrusion being inserted into the fourth gas passage, and the second valve sheet has a second protrusion protruding towards the inside, the second protrusion being inserted into the third gas passage.

[0028] In some possible embodiments, the first valve sheet has a first circular shape formed by two first semicircles, the second valve sheet has a second circular shape formed by two second semicircles, the first gas passage and the first protrusion are respectively arranged on the two first semicircles, and the second gas passage and the second protrusion are respectively arranged on the two second semicircles.

[0029] When viewed along a direction perpendicular to the partition plate, the first semicircle provided with the first gas passage and the second semicircle provided with the second protrusion completely overlap with each other, and the first semicircle provided with the protrusion and the second semicircle provided with the second first gas passage completely overlap with each other.

[0030] In some possible embodiments, the breathing valve further comprises:

[0031] Two filter sheets are arranged in the air channel and located at the inside and outside of the desiccant respectively.

[0032] In a second aspect, the present application provides a breathing valve for being mounted to a box of a battery pack, the box having an inner cavity for accommodating a battery module, the breathing valve comprising:

[0033] An air channel comprising a first channel segment and a second channel segment, the second channel segment being arranged in series at the outside of the first channel segment.

[0034] A desiccant arranged in the first channel segment.

[0035] A valve sheet assembly arranged in the second channel segment and configured to be in a closed state when the air pressure in the inner cavity is equal to the air pressure in the external environment, thereby cutting off the second channel segment, and in an open state when the air pressure in the inner cavity is higher or lower than the air pressure in the external environment, thereby making the second channel segment conductive.

[0036] According to the battery pack provided in the present application, the battery pack comprises a box body having an inner cavity, a battery module accommodated in the inner cavity, and a breather valve mounted to the box body, the breather valve being used for selectively connecting or blocking the inner cavity with the external environment in gas phase. The breather valve comprises an air passage comprising a first passage section and a second passage section, the second passage section being connected in series outside the first passage section; a desiccant arranged in the first passage section; and a valve plate assembly arranged in the second passage section and configured to be in a closed state when the air pressure in the inner cavity is equal to the air pressure in the external environment, thereby cutting off the second passage section, and in an open state when the air pressure in the inner cavity is higher or lower than the air pressure in the external environment, thereby making the second passage section conductive. In this way, on the one hand, the desiccant of the breather valve can dehumidify the air entering the box, on the other hand, the air discharged from the box body can take away the moisture in the desiccant of the breather valve, thereby prolonging the service life of the desiccant, and on the other hand, when the air pressure in the box body is relatively balanced, the air in the environment cannot enter the box body, and the desiccant does not perform ineffective moisture absorption, thereby maintaining the moisture absorption capacity of the desiccant. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described in the following description only relate to some embodiments of the present application, but not limit the present application.

[0038] Figure 1 FIG. 1 is a perspective schematic view of a battery pack in an embodiment of the present application.

[0039] Figure 2 FIG. 2 is a top perspective schematic view of the battery pack in the embodiment of the present application.

[0040] Figure 3 FIG. 3 is an exploded schematic view of the battery pack in the embodiment of the present application, with part of the structure removed.

[0041] Figure 4 FIG. 4 is a structural schematic view of part of the structure in the embodiment of the present application, with part of the structure removed. Figure 3

[0042] FIG. 5 is a partial enlarged view of the embodiment of the present application. Figure 5 Figure 4 FIG. 6 is a partial enlarged view of the embodiment of the present application.

[0043] BRIEF DESCRIPTION OF DRAWINGS

[0044] 100 - box body, 200 - battery module, 300 - breather valve;

[0045] 1 - air passage, 1A - first passage section, 1B - second passage section;

[0046] 2 - desiccant;

[0047] ​3 - first valve piece, 3A - first air hole, 3B - first protrusion;

[0048] 4 - second valve piece, 4A - second air hole;

[0049] 5 - partition, 5A - inner side surface, 5B - outer side surface, 5C - third air hole, 5D - fourth air hole;

[0050] 6 - first pressing piece, 6A - first hole;

[0051] 7 - second pressing piece, 7A - second hole;

[0052] 8 - bolt;

[0053] 9 - nut;

[0054] 10 - filter piece;

[0055] 11 - annular clamping groove;

[0056] 12 - metal blocking piece;

[0057] 13 - clamping spring. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application. It can be understood that some technical means of the various embodiments described herein can be replaced or combined with each other without conflict.

[0059] In the description of the present application, if there are terms such as "first", "second", etc., they are only used to distinguish the described objects, and do not have any order or technical meaning. Therefore, the objects defined with "first", "second", etc. can be explicitly or implicitly include one or more of the objects. And "one" or "an" and the like similar words do not represent a quantity limit, but represent the existence of at least one, and "more" represents no less than two.

[0060] Figures 1 to 5One embodiment of the battery pack of the present application is shown, which includes a box 100, a battery module 200 and a breather valve 300. The box 100 has a square shape and has a substantially square inner cavity. The battery module 200 is received in the inner cavity of the box 100, and the battery module 200 can be composed of a plurality of battery cells electrically connected. The breather valve 300 is mounted to the box 100 and is used to selectively connect or disconnect the inner cavity with the external environment in gas phase. In the description of the present application, the direction away from the inner cavity is defined as the outer side direction, and the direction close to the inner cavity is defined as the inner side direction in the extension direction of the air passage 1 (i.e. in the direction of the air flow in the air passage 1).

[0061] The box 100 can be composed of a box body having an opening and a cover closing the opening, and the inner cavity is formed between the box body and the cover. The breather valve 300 can be mounted to the box body or the cover.

[0062] The breather valve 300 includes a valve body, an air passage 1, a desiccant 2 and a valve plate assembly.

[0063] The valve body defines the housing of the breather valve 300, or in other words, the valve body includes the housing of the breather valve 300.

[0064] The air passage 1 is formed in the valve body and is used for the air flow to enable the air to flow between the inner cavity and the external environment when the breather valve 300 is in the open state (correspondingly, the air passage 1 is in the conductive state). The air passage 1 includes a first passage segment 1A and a second passage segment 1B, and the second passage segment 1B is connected in series on the outer side of the first passage segment 1A. In this way, when the breather valve 300 is in the open state, the air flowing out of the inner cavity first passes through the first passage segment 1A and then passes through the second passage segment 1B to reach the external environment, and the air flowing from the external environment first passes through the second passage segment 1B and then passes through the first passage segment 1A to reach the inner cavity.

[0065] The desiccant 2 is arranged in the first passage segment 1A, and the valve plate assembly is arranged in the second passage segment 1B, and the valve plate assembly is configured to be in the closed state when the air pressure of the inner cavity is equal to the air pressure of the external environment, thereby cutting off the second passage segment 1B, and to be in the open state when the air pressure of the inner cavity is higher or lower than the air pressure of the external environment, thereby making the second passage segment 1B conductive. In this way, when the valve plate assembly is in the closed state and thereby cuts off the second passage, the air in the external environment with moisture cannot contact the desiccant 2 inside the valve plate assembly, thereby avoiding the invalid moisture absorption of the desiccant 2 and prolonging the service life of the desiccant 2. The amount of the desiccant 2 can be selected according to the size and service life requirements of the battery pack.

[0066] The valve plate assembly includes a partition plate 5, a first valve plate 3 and a second valve plate 4, and the first valve plate 3 and the second valve plate 4 are respectively located on the inner side and the outer side of the partition plate 5.

[0067] The partition 5 is integrally formed on the valve body, and has an inner side surface 5A, an outer side surface 5B opposite to the inner side surface 5A, a third gas passage 5C and a fourth gas passage 5D penetrating from the inner side surface 5A to the outer side surface 5B and spaced from each other. In the present embodiment, the third gas passage 5C and the fourth gas passage 5D are both arc-shaped long holes, and arranged on the same circumference.

[0068] The first valve plate 3 is elastically deformable, and has a first gas passage 3A penetrating therethrough. The second valve plate 4 is also elastically deformable, and has a second gas passage 4A penetrating therethrough.

[0069] In the present embodiment, the first gas passage 3A and the second gas passage 4A are respectively provided as a plurality of holes, the plurality of first gas passages 3A are arranged in a circular arc shape, the plurality of second gas passages 4A are arranged in another circular arc shape, and the two circular arc shapes are coaxially arranged and respectively located on two sides of the axis in the radial direction. Obviously, the first gas passage 3A and the second gas passage 4A can also be respectively provided as only one hole.

[0070] In the initial state, the gas pressure in the inner cavity is equal to the gas pressure of the external environment, the first valve plate 3 is pressed against the inner side surface 5A of the partition 5, thereby sealing the fourth gas passage 5D (more specifically, the inner side hole of the fourth gas passage 5D, i.e. the hole of the fourth gas passage at the inner side surface 5A), the second valve plate 4 is pressed against the outer side surface 5B of the partition 5, thereby sealing the third gas passage 5C (more specifically, the outer side hole of the third gas passage 5C, i.e. the hole of the third gas passage at the outer side surface 5B), and the first gas passage 3A is in communication with the third gas passage 5C, and the second gas passage 4A is in communication with the fourth gas passage 5D.

[0071] When the air pressure in the inner cavity is lower than the air pressure in the external environment, the first valve sheet 3 is elastically deformed towards the inner side under the air pressure, so as to form a first air gap between the first valve sheet 3 and the inner side surface 5A, thereby releasing the blocking of the fourth air hole 5D by the first valve sheet 3 and making the fourth air hole 5D communicate with the first air hole 3A via the first air gap. Specifically, the air pressure in the inner cavity is applied to the inner side of the first valve sheet 3 via the first channel section 1A, and the air pressure in the external environment is applied to the outer side of the first valve sheet 3 via the second air hole 4A of the second valve sheet 4 and the fourth air hole 5D of the partition plate 5. Since the air pressure in the inner cavity is lower than the air pressure in the external environment, there is an air pressure difference between the inner and outer sides of the first valve sheet 3, so that the first valve sheet 3 is elastically deformed towards the inner side. Thus, the outer side of the first valve sheet 3, which originally blocks the fourth air hole 5D, is separated from the fourth air hole 5D, the blocking of the fourth air hole 5D is released, and the first air gap is formed between the first valve sheet 3 and the inner side surface 5A. In this way, the air in the external environment can enter the inner cavity of the box body 100 via the fourth air hole 5D of the partition plate 5, the first air gap, the first air hole 3A of the first valve sheet 3, the first channel section 1A provided with the desiccant 2, and the desiccant 2 in sequence, and is dried by the desiccant 2.

[0072] When the air pressure in the inner cavity is lower than the air pressure in the external environment, the first valve sheet 3 is elastically deformed towards the inner side under the air pressure, so as to form a first air gap between the first valve sheet 3 and the inner side surface 5A, thereby releasing the blocking of the fourth air hole 5D by the first valve sheet 3 and making the fourth air hole 5D communicate with the first air hole 3A via the first air gap. Specifically, the air pressure in the inner cavity is applied to the inner side of the first valve sheet 3 via the first channel section 1A, and the air pressure in the external environment is applied to the outer side of the first valve sheet 3 via the second air hole 4A of the second valve sheet 4 and the fourth air hole 5D of the partition plate 5. Since the air pressure in the inner cavity is lower than the air pressure in the external environment, there is an air pressure difference between the inner and outer sides of the first valve sheet 3, so that the first valve sheet 3 is elastically deformed towards the inner side. Thus, the outer side of the first valve sheet 3, which originally blocks the fourth air hole 5D, is separated from the fourth air hole 5D, the blocking of the fourth air hole 5D is released, and the first air gap is formed between the first valve sheet 3 and the inner side surface 5A. In this way, the air in the external environment can enter the inner cavity of the box body 100 via the fourth air hole 5D of the partition plate 5, the first air gap, the first air hole 3A of the first valve sheet 3, the first channel section 1A provided with the desiccant 2, and the desiccant 2 in sequence, and is dried by the desiccant 2.

[0073] In the present embodiment, the first valve sheet 3 and the second valve sheet 4 are both made of silica gel, i.e., both are relatively soft and elastic silica gel sheets.

[0074] The valve plate assembly also includes a first pressure plate 6 and a second pressure plate 7. The first pressure plate 6 is stacked inside the first valve plate 3 and applies a slight pressing force to the first valve plate 3 toward its inner surface 5A. The second pressure plate 7 is stacked outside the second valve plate 4 and applies a slight pressing force to the second valve plate 4 toward its outer surface 5B.

[0075] In this embodiment, both the first pressing plate 6 and the second pressing plate 7 are made of metal, that is, both are metal sheets. In other embodiments, the first pressing plate 6 and the second pressing plate 7 are made of plastic.

[0076] Furthermore, the valve plate assembly also includes a tensioning element comprising a bolt 8 and a nut 9. The head of the bolt 8 passes sequentially from the outside in through the second pressure plate 7, the second valve plate 4, the partition 5, the first valve plate 3, and the first pressure plate 6, before engaging with the nut 9. Thus, the tensioning element holds the second pressure plate 7, the second valve plate 4, the partition 5, the first valve plate 3, and the first pressure plate 6 together, and the silicone-material first valve plate 3 and the second valve plate 4 are in a non-natural state of compression and collapse deformation. Therefore, to resist the elastic force that allows the first valve plate 3 and the second valve plate 4 to recover their deformation, the bolt 8 and nut 9 assembly applies a tensioning force to the first pressure plate 6 and the second pressure plate 7, intending to bring them closer together in the inward and outward directions. Consequently, the first pressure plate 6 presses the first valve plate 3 outward, and the second pressure plate 7 presses the second valve plate 4 inward.

[0077] The first pressure plate 6 has multiple through holes 6A, which are evenly and densely distributed across the entire area of ​​the first pressure plate 6. The second pressure plate 7 has multiple through holes 7A, which are densely distributed across the entire area of ​​the second pressure plate 7. Thus, during assembly, regardless of the angle at which the first pressure plate 6 and the second pressure plate 7 are positioned, there will always be a corresponding first hole 6A overlapping with the first vent hole 3A on the first valve plate 3, and there will always be a corresponding second hole 7A overlapping with the second vent hole 4A on the second valve plate 4. This prevents the first pressure plate 6 from cutting off the gas phase from the inner cavity to the first vent hole 3A, and prevents the second pressure plate 7 from cutting off the gas phase from the external environment to the second vent hole 4A.

[0078] Specifically, when viewed along a direction perpendicular to the partition 5, a portion of the first hole 6A, a portion of the second hole 7A, the first vent 3A, and the third vent 5C overlap, while another portion of the first hole 6A, another portion of the second hole 7A, the second vent 4A, and the fourth vent 5D overlap. The third vent 5C is completely covered by the second valve plate 4, and the fourth vent 5D is completely covered by the first valve plate 3. Each of the first vent 3A and the third vent 5C is separated from each of the second vent 4A and the fourth vent 5D.

[0079] It is understandable that the densely packed first holes 6A on the first pressure plate 6 provide inward deformation space for the first valve plate 3. This allows the first valve plate 3 to easily undergo inward elastic deformation when the ambient air pressure is greater than the internal air pressure, thus ensuring the smooth opening of the air passage 1. Similarly, the densely packed second holes 7A on the second pressure plate 7 provide outward deformation space for the second valve plate 4. This allows the second valve plate 4 to easily undergo outward elastic deformation when the internal air pressure is greater than the ambient air pressure, thus ensuring the smooth opening of the air passage 1 of the breathing valve 300.

[0080] Furthermore, the first valve plate 3 has a first protrusion 3B protruding outward, which is inserted into the fourth vent hole 5D. The second valve plate 4 has a second protrusion (not shown) protruding inward, which is inserted into the third vent hole 5C. Thus, the third vent hole 5C and the fourth vent hole 5D not only provide ventilation but also position the assembly angles of the first valve plate 3 and the second valve plate 4. In addition, when the first valve plate 3 and the second valve plate 4 deform due to air pressure, the protruding first protrusion 3B and the second protrusion will not completely detach from the fourth vent hole 5D and the third vent hole 5C. This prevents changes in the angular position of the first valve plate 3 and the second valve plate 4 relative to the partition 5, which could lead to the first vent hole 3A completely misaligning with the third vent hole 5C, and the second vent hole 4A completely misaligning with the fourth vent hole 5D, thereby preventing the breather valve 300 from opening successfully.

[0081] The first valve plate 3 is shaped like a first circle formed by two first semicircles, and the second valve plate 4 is shaped like a second circle formed by two second semicircles. A first vent 3A and a first protrusion 3B are respectively disposed on the two first semicircles, and a second vent 4A and a second protrusion are respectively disposed on the two second semicircles. When viewed along a direction perpendicular to the partition 5, the first semicircle with the first vent 3A and the second semicircle with the second protrusion completely overlap each other, and the first semicircle with the protrusion and the second semicircle with the second vent 3A completely overlap each other.

[0082] In addition, to prevent the desiccant 2 and dust from the environment from entering the inner cavity of the housing 100, this embodiment also provides three filter sheets 10 in the air channel 1. Two of the filter sheets 10 are located inside and outside the desiccant 2, respectively (that is, these two filter sheets 10 are arranged in the extending direction of the air channel 1 with the desiccant 2 in between), and the other filter sheet 10 is located outside the second valve plate 4. The filter sheet 10 is specifically made of non-woven fabric.

[0083] Specifically, three annular slots 11 are formed on the inner wall of the air channel 1, spaced apart from the inside out. A metal baffle 12 with mesh and a non-woven fabric serving as a filter 10 are stacked together and engaged in the annular slots 11 by a retaining spring 13. More specifically, the retaining spring 13 engages the metal baffle 12 and the filter 10 into the annular slots 11 on the side of the filter 10 facing away from the metal baffle 12, and the filter 10 is sandwiched between the retaining spring 13 and the metal baffle 12.

[0084] In addition, a desiccant 2 is placed inside the battery pack housing 100 to absorb moisture from the air entering the housing. This desiccant 2 can be packaged in flame-retardant PET or PP material with slow-permeability, and the package is fixed to the inner wall of the housing 100 with strong double-sided adhesive. The desiccant 2 inside the housing 100 can be a combination of magnesium chloride and magnesium hydroxide reactive desiccant 2, eliminating the risk of secondary moisture reabsorption.

[0085] Additionally, the bottom of the housing 100 is lined with absorbent nonwoven fabric (not shown) to absorb moisture in the interior of the housing 100—such as battery fluid leaking from the battery module 200. The absorbent nonwoven fabric may include an upper absorbent layer and a leak-proof layer laminated below the absorbent layer, wherein the leak-proof layer may be a flame-retardant PET film.

Claims

1. A battery pack, comprising: The box-shaped enclosure has an internal cavity. The battery module is housed within the cavity; A breathing valve, installed in the housing, is used to selectively connect the inner cavity to the external environment or block the gas phase. The breathing valve is characterized in that it comprises: An air passage includes a first passage segment and a second passage segment, wherein the second passage segment is connected in series to the outside of the first passage segment; Desiccant is disposed in the first channel section; A valve assembly, disposed in the second channel section, is configured such that: when the air pressure in the inner cavity is equal to the air pressure of the external environment, it is in a closed state, thereby cutting off the second channel section; and when the air pressure in the inner cavity is higher or lower than the air pressure of the external environment, it is in an open state, thereby opening the second channel section. The valve assembly includes: The first valve plate is elastically deformable and has a through first air outlet; The second valve plate is elastically deformable and has a through second air outlet; A partition is disposed between the first valve plate and the second valve plate, and has an inner surface, an outer surface opposite to the inner surface, a third vent hole and a fourth vent hole that extend from the inner surface to the outer surface and are spaced apart from each other. In the initial state, the first valve plate presses against the inner surface, thereby blocking the fourth vent hole; the second valve plate presses against the outer surface, thereby blocking the third vent hole; and the first vent hole communicates with the third vent hole, while the second vent hole communicates with the fourth vent hole. When the air pressure inside the cavity is lower than the air pressure of the external environment, the first valve plate undergoes elastic deformation towards the inward side under the action of air pressure, thereby forming a first ventilation gap between the first valve plate and the inner surface. This allows the first valve plate to release the blockage of the fourth vent hole and allows the fourth vent hole to communicate with the first vent hole through the first ventilation gap. When the air pressure in the inner cavity is higher than the air pressure in the external environment, the second valve plate undergoes elastic deformation towards the outside under the action of air pressure, thereby forming a second ventilation gap between the second valve plate and the outer surface. This allows the second valve plate to release the blockage of the fourth vent hole and allows the third vent hole to communicate with the second vent hole through the second ventilation gap.

2. The battery pack according to claim 1, characterized in that, Both the first valve plate and the second valve plate are made of silicone.

3. The battery pack according to claim 1 or 2, characterized in that, The valve assembly also includes: The first pressure plate is stacked on the inner side of the first valve plate and applies a pressing force toward the inner surface of the first valve plate; The second pressure plate is stacked on the outside of the second valve plate and applies a pressing force toward the outer surface of the second valve plate.

4. The battery pack according to claim 3, characterized in that, The valve assembly also includes: A tensioning element is disposed through the first pressure plate, the first valve plate, the partition plate, the second valve plate, and the second pressure plate, and applies a tensioning force to bring the first pressure plate and the second pressure plate closer to each other in the inward and outward directions.

5. The battery pack according to claim 3, characterized in that, The first tablet has a plurality of through first holes, and the second tablet has a plurality of through second holes; When viewed along a direction perpendicular to the partition, a portion of the first hole, a portion of the second hole, the first vent hole, and the third vent hole overlap; another portion of the first hole, another portion of the second hole, the second vent hole, and the fourth vent hole overlap; the third vent hole is completely covered by the second valve plate; the fourth vent hole is completely covered by the first valve plate; each of the first and third vent holes is separated from each of the second and fourth vent holes.

6. The battery pack according to claim 1, characterized in that, The first valve plate has a first protrusion protruding outward, which is inserted into the fourth vent hole. The second valve plate has a second protrusion protruding inward, which is inserted into the third vent hole.

7. The battery pack according to claim 6, characterized in that, The first valve plate is in the shape of a first circle formed by two first semicircles, and the second valve plate is in the shape of a second circle formed by two second semicircles. The first vent hole and the first protrusion are respectively disposed on the two first semicircles, and the second vent hole and the second protrusion are respectively disposed on the two second semicircles. When viewed along a direction perpendicular to the partition, the first semicircle with the first vent hole and the second semicircle with the second protrusion completely overlap each other.

8. The battery pack according to claim 1, characterized in that, The breathing valve also includes: Two filter elements are disposed in the air channel, and are located on the inside and outside of the desiccant, respectively.

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