Directional pressure relief soft package battery and directional pressure relief soft package battery module
By setting pressure relief sections and pressure devices at the edge of the pouch battery encapsulation film, directional pressure relief of the battery is achieved, solving the safety problem of thermal runaway in pouch batteries and improving the safety and reliability of the battery.
Patent Information
- Application Number
- CN202520133282.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2026-01-30
- Estimated Expiration
- 2035-01-20
AI Technical Summary
During use, the internal pressure of pouch batteries increases due to gas generation, causing the seals to randomly break open, which poses a risk of thermal runaway and affects the safety of surrounding batteries.
The design of a directional pressure relief pouch battery involves setting a pressure relief section at the edge of the encapsulation film, making its width in the first direction smaller than that of the non-pressure relief section. This ensures that gas is preferentially discharged from a specific location. Combined with a pressure device, an internal force is applied to the battery cell to achieve directional pressure relief.
It improves battery safety, avoids uncontrolled safety issues in surrounding batteries caused by random gas emissions, prevents pressure imbalances and toxic gas accumulation, and ensures directional pressure relief of the battery in the event of thermal runaway.
Smart Images
Figure CN223858371U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure relates to the technical field of batteries, and in particular to a directional pressure relief soft package battery and a directional pressure relief soft package battery module. BACKGROUND
[0002] A soft package battery is a lithium ion battery packaged with flexible packaging materials. Unlike traditional cylindrical or square hard-shell batteries, soft package batteries use aluminum-plastic composite film as the shell, which not only reduces weight, but also provides higher space utilization and better safety. Soft package batteries are widely used in consumer electronics, electric vehicles, portable medical devices, and energy storage systems.
[0003] In the related art, soft package batteries generate gas during use, causing the internal pressure of the battery to increase and the battery to swell. When the internal pressure of the battery continues to increase beyond the limit that the sealing edge can withstand, the sealing edge of the battery shell will be burst open, and the battery will be relieved. Since the pressure on the sealing edge of the battery is uniform, the position of the sealing edge burst open is also random, which may affect the safety of other batteries around, and there is a risk of causing thermal runaway. UTILITY MODEL CONTENT
[0004] To solve the above technical problems, the present disclosure provides a directional pressure relief soft package battery and a directional pressure relief soft package battery module.
[0005] The present disclosure provides a directional pressure relief soft package battery, comprising a battery cell, wherein: the battery cell comprises a packaging film, at the edge of the battery cell, two layers of the packaging film form a packaging side edge, and the packaging side edge comprises at least one pressure relief part; in a first direction, the width of the packaging side edge at the position of the pressure relief part is less than the width of the packaging side edge at the position of a non-pressure relief part; the first direction points from the center of the battery cell to the packaging side edge where the pressure relief part is located, and is perpendicular to the thickness direction of the packaging film.
[0006] Optionally, in the first direction, the width of the packaging side edge at the position of the pressure relief part is between 1.5 mm and 10 mm.
[0007] Optionally, in a second direction, the length of the pressure relief part is between 5 mm and 100 mm; the second direction is perpendicular to the first direction and the thickness direction of the packaging film.
[0008] Optionally, two to six pressure relief parts are included on one battery cell.
[0009] Optionally, the pressure relief portions on one of the battery cells are located on one of the package sides; or, the pressure relief portions on one of the battery cells are located on two opposite package sides respectively; or, the pressure relief portions on one of the battery cells are located on two adjacent package sides respectively; or, the pressure relief portions on one of the battery cells are located on three adjacent package sides respectively.
[0010] Optionally, the package film comprises a cast polypropylene film layer; the deformation amount of the cast polypropylene film layer at the position of at least part of the pressure relief portions is less than the deformation amount of the cast polypropylene film layer at the position of non-pressure relief portions.
[0011] Optionally, the deformation amount of the cast polypropylene film layer at the position of at least part of the pressure relief portions is between 3% and 20%.
[0012] Optionally, at least one set of pressure devices is further included; the pressure devices are arranged around the battery cells and are used to apply an action force to the battery cells, which is directed to the inside of the battery cells; in the direction from the inside of the battery cells to the outside of the battery cells, the pressure devices do not overlap with the pressure relief portions.
[0013] Optionally, at least two sets of the pressure devices are included, and at least one of the pressure relief portions is located between the two sets of the pressure devices.
[0014] Based on the same inventive concept, the disclosure further provides a soft-pack battery module with directional pressure relief, comprising at least two battery cells and at least one set of pressure devices, wherein: the pressure devices are arranged around all the battery cells and are used to apply an action force to the battery cells, which is directed to the inside of the battery cells; in the direction from the inside of the battery cells to the outside of the battery cells, the pressure devices do not overlap with the pressure relief portions.
[0015] The technical solutions provided by the disclosure have the following advantages compared with the prior art: the soft-pack battery with directional pressure relief provided by the disclosure is provided with pressure relief portions, which ensure that the gas generated inside the battery can preferentially break through the pressure relief portions when the battery is in thermal runaway, so as to realize the directional pressure relief of the battery and improve the safety of the battery. BRIEF DESCRIPTION OF DRAWINGS
[0016] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the disclosure and, together with the specification, serve to explain the principles of the disclosure.
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings without any creative effort.
[0018] Figure 1 A front view structural schematic diagram of a directional pressure relief soft package battery provided by the embodiments of the present disclosure;
[0019] Figure 2 A sectional view structural schematic diagram of a directional pressure relief soft package battery provided by the embodiments of the present disclosure;
[0020] Figure 3 A film layer structural schematic diagram of a packaging film provided by the embodiments of the present disclosure;
[0021] Figure 4 Another front view structural schematic diagram of a directional pressure relief soft package battery provided by the embodiments of the present disclosure;
[0022] Figure 5 Another side view structural schematic diagram of a directional pressure relief soft package battery provided by the embodiments of the present disclosure;
[0023] Figure 6 A side view structural schematic diagram of a directional pressure relief soft package battery module provided by the embodiments of the present disclosure. DETAILED DESCRIPTION
[0024] In order to more clearly illustrate the above-mentioned purposes, features and advantages of the embodiments of the present disclosure, the solutions of the embodiments of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.
[0025] In the following description, many specific details are set forth in order to fully understand the embodiments of the present disclosure, but the embodiments of the present disclosure can also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some of the embodiments of the present disclosure, not all the embodiments.
[0026] In the related art, for cylindrical batteries and square shell batteries, by setting a pressure relief valve, it is ensured that the pressure relief valve can be opened and realize directional pressure relief when the battery is in thermal runaway, so as to avoid or delay the fire and explosion of the battery. However, soft package batteries are difficult to realize the directional pressure relief function because they cannot install a pressure relief valve (the packaging film itself is relatively soft, and there is no reliable place to support the installation of the pressure relief valve).
[0027] Therefore, the embodiments of the present disclosure provide a directional pressure relief soft package battery, as shown in Figure 1 and Figure 2 Figure 1 is a front view of a directional pressure relief pouch battery in an embodiment, Figure 2 is a front view of a directional pressure relief pouch battery in an embodiment, Figure 1 is a sectional view along L1 in an embodiment, including a battery cell 10, wherein:
[0028] The battery cell 10 includes an encapsulation film 12, at the edge of the battery cell 10, two layers of the encapsulation film 12 form an encapsulation side edge 13, and the encapsulation side edge 13 includes at least one pressure relief portion 130. The drawings are only exemplary, and in actual implementation, the pressure relief portion 130 can also be located on other encapsulation side edges 13.
[0029] In a first direction X, the width d1 of the encapsulation side edge 13 at the position of the pressure relief portion 130 is less than the width d2 of the encapsulation side edge 13 at the position of the non-pressure relief portion. The first direction X points from the center of the battery cell 10 to the encapsulation side edge 13 where the pressure relief portion 130 is located, and is perpendicular to the thickness direction Z of the encapsulation film 12 (as shown in Figure 3 The width d1 of the encapsulation side edge 13 at the position of the pressure relief portion 130 is less than the width d2 of the encapsulation side edge 13 at the position of the non-pressure relief portion, so that the pressure limit that the encapsulation side edge 13 at the position of the pressure relief portion 130 can withstand is less than that of the non-pressure relief portion. When the internal pressure of the battery cell 10 continues to increase to exceed the limit that the encapsulation side edge can withstand, the pressure relief portion 130 will be the first to be broken, thereby controlling the gas to be discharged from a specific position, avoiding the problem of safety loss of control of surrounding batteries caused by random discharge of gas, and realizing directional pressure relief of the battery. Moreover, when the battery is in thermal runaway, directional pressure relief discharge can avoid imbalance of internal and external pressure in the battery pack, and prevent immediate generation and accumulation of toxic gas.
[0030] The directional pressure relief pouch battery provided by the embodiment of the present disclosure ensures that the gas generated inside the battery can first break through the pressure relief portion 130 when the battery is in thermal runaway, realizes directional pressure relief of the battery, and improves the safety of the battery.
[0031] In specific implementation, inside the aforementioned encapsulation film 12, the aforementioned battery cell 10 includes, but is not limited to, the following components: Cathode: The positive electrode material of a pouch battery typically uses lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and ternary materials. The positive electrode is formed by laminating a mixture of positive electrode materials onto a metal foil (such as aluminum foil) as the current collector; Anode: The negative electrode material of a pouch lithium battery generally uses graphite, silicon, or a mixture of graphite and silicon. The negative electrode is formed by laminating a mixture of negative electrode materials onto a metal foil as the current collector; Separator: The separator in a pouch battery isolates the positive and negative electrodes, preventing short circuits and mixing of ions in the electrolyte. The separator is usually made of polymer materials, such as polypropylene or polyethylene; the electrolyte is usually composed of organic solvents and lithium salts. Common organic solvents include carbonates, esters and polymer electrolytes. The lithium salt is usually lithium hydrochloride (such as LiPF6, LiBF4, etc.). The electrolyte plays a role in ion transport between the positive and negative electrodes.
[0032] In specific implementation, the aforementioned encapsulation film 12 is an aluminum-plastic film, which is made of multiple layers of composite materials bonded together by adhesives. The aluminum-plastic film has the characteristics of high barrier properties, heat resistance and insulation, stable performance, convenient encapsulation, as well as flexibility and ductility.
[0033] In specific implementation, such as Figure 1 As shown, the battery cell 10 also includes positive and negative tabs 14, which are metal conductors that connect the internal and external circuits of the battery cell 10. They are usually made of aluminum or nickel and are encapsulated together with the encapsulation film 12 by tab adhesive.
[0034] In some embodiments, such as Figure 1 As shown, a battery cell 10 includes two to six pressure relief sections 130. All pressure relief sections 130 on a battery cell 10 are located on a single encapsulation side 13; or, as... Figure 1 As shown, the pressure relief portion 130 on a battery cell 10 is located on two opposite encapsulation sides 13; or, the pressure relief portion 130 on a battery cell 10 is located on two adjacent encapsulation sides 13; or, the pressure relief portion 130 on a battery cell 10 is located on three adjacent encapsulation sides 13.
[0035] Since different pouch batteries are used in different locations, the direction of pressure relief also varies. The specific location of the pressure relief part 130 on the battery cell 10 can be further determined based on the actual application, and will not be limited here.
[0036] In practice, the aforementioned pressure relief part 130 can be manufactured using a precise positioning punching process.
[0037] Punching is a stamping process that uses molds to separate sheet metal. It has advantages such as high precision, high efficiency, and versatility, and can quickly separate materials and process a variety of materials.
[0038] In some embodiments, such as Figure 1 As shown, in the first direction X, the width d1 of the package side 13 at the pressure relief portion 130 is between 1.5 mm and 10 mm. For a pouch battery, a width of 1.5 mm for the package side 13 ensures packaging effectiveness. For the package side 13 at locations other than the pressure relief portion, its width can be appropriately increased to further improve packaging effectiveness. Specifically, the width d1 of the package side 13 at the pressure relief portion 130 can be between 30% and 80% of the width d2 of the package side 13 at locations other than the pressure relief portion.
[0039] In some embodiments, such as Figure 1 As shown, in the second direction Y, the length d3 of the pressure relief portion 130 is between 5 mm and 100 mm; the second direction Y is perpendicular to the first direction X and the thickness direction Z of the encapsulation film.
[0040] In some embodiments, such as Figure 3 As shown, the encapsulation film 12 includes a cast polypropylene film layer (CPP-Layer) 201; the deformation of the cast polypropylene film layer 201 at at least the partial pressure relief portion 130 position is less than the deformation of the cast polypropylene film layer 201 at the non-pressure relief portion position.
[0041] Specifically, Figure 3 The specific film structure of the single-layer encapsulation film 12 is shown. The encapsulation film 12 is an aluminum-plastic film, a multi-layer composite film material. In addition to the aforementioned cast polypropylene film layer 201, its structure includes an onyx layer 202, a multi-layer adhesive layer 203, a multi-layer anti-corrosion layer 204, and an aluminum foil layer 205. The cast polypropylene film layer 201 is located on the side of the aluminum-plastic film closest to the inside of the battery. It is a plastic film material, and its excellent flexibility and high-temperature sealing properties make it suitable for encapsulating pouch batteries.
[0042] During the packaging of the pouch battery, the encapsulation film 12 is heat-sealed at the edge of the battery cell 10. During the heat-sealing process, part of the material of the encapsulation film 12 is heated above its softening point, making the material surface sticky. At the same time, pressure is applied to ensure that the two layers of encapsulation film 12 are tightly bonded to form a seal, namely the aforementioned encapsulation side 13. During the heat-sealing process, the aforementioned cast polypropylene film layer 201 will deform. The smaller the deformation, the less effective the heat sealing, and the easier it is for the encapsulation side 13 to break. Reducing the deformation of the cast polypropylene film layer 201 at at least part of the pressure relief portion 130 can further ensure that, in the event of thermal runaway, the gas generated inside the battery can preferentially break through the pressure relief portion 130 from the position with the smaller deformation. At the same time, in order to ensure the effectiveness of the encapsulation, the deformation of the cast polypropylene film layer 201 at non-pressure relief portions will be larger, but it is necessary to control the process parameters such as encapsulation temperature, pressure, and time to ensure that the deformation is controlled within the process requirements to avoid encapsulation failure.
[0043] In some embodiments, the deformation of the cast polypropylene film layer 201 at at least a portion of the pressure relief portion 130 is between 3% and 20%. In specific embodiments, the deformation of the cast polypropylene film layer 201 at non-pressure relief portions is between 20% and 40%.
[0044] In practice, during the heat sealing process of the encapsulation film 12, the deformation of the cast polypropylene film layer 201 is controlled between 3% and 20% by process parameters. This allows the cast polypropylene film layer 201 to rupture preferentially at a preset position (such as the pressure relief part 130) when the internal pressure of the battery changes, so as to release the internal pressure, prevent the battery from exploding or being damaged, and at the same time ensure the directional pressure relief of the battery.
[0045] In some embodiments, such as Figure 4 and Figure 5 As shown (( Figure 4 and Figure 5 (The images shown are a front view and a side view of a directional pressure relief pouch battery in one embodiment.) The directional pressure relief pouch battery provided in this embodiment also includes a pressure device 20.
[0046] The pressure device 20 is arranged around the battery cell 10 and is used to apply a force to the battery cell 10 in the direction of the battery cell 10. The pressure device 20 plays a restraining role and can reduce the degree of deformation of the battery in the event of thermal runaway, thereby improving the safety of the battery.
[0047] In the direction from the inside of the battery cell 10 to the outside of the battery cell 10, the pressure device 20 and the pressure relief part 130 do not overlap, further ensuring that the gas generated inside the battery can preferentially break through the pressure relief part 130 when the battery is in thermal runaway.
[0048] The embodiments of this disclosure, by setting up a pressure device 20, reduce the degree of deformation of the battery during thermal runaway, and further ensure that the gas generated inside the battery can preferentially break through the pressure relief section 130, thereby achieving directional pressure relief of the battery and further improving battery safety.
[0049] In practice, the force applied by the pressure device 20 to the battery cell 10, directed towards the inside of the battery cell 10, can be from 0.001 MPa to 10 MPa, which can be determined according to the specific model and size of the battery. No further limitations are imposed here.
[0050] In practical implementation, the aforementioned pressure device 20 can be a metal cable tie, such as stainless steel, aluminum, or carbon steel, which can be used as part of the cable tie to prevent damage when the battery expands and improve connection reliability. Alternatively, the pressure device 20 can be a plastic cable tie, such as PET plastic, to save costs.
[0051] It is understood that the pressure device 20 in the accompanying drawings of the embodiments of this disclosure is only used to define its positional relationship with the battery cell 10, and does not limit the pressure device 20 to be an integral structure. In some other embodiments, the pressure device 20 may be composed of multiple components. For example, the pressure device 20 may include a first clamping plate and a second clamping plate located on both sides of the battery cell 10, connected by screws or other connecting members, and applying a force to the battery cell 10 pointing inward.
[0052] It is understood that the number of pressure devices 20 in the accompanying drawings of the embodiments of this disclosure is merely exemplary. Those skilled in the art can select and implement the corresponding number of pressure devices 20 according to the size of the battery in a specific implementation, all of which are within the protection scope of this disclosure.
[0053] In some embodiments, such as Figure 4 and Figure 5 As shown, a directional pressure relief pouch cell includes at least two sets of pressure devices 20, with at least one pressure relief section 130 located between the two sets of pressure devices 20, further ensuring that in the event of thermal runaway, the gas generated inside the battery can preferentially break through the pressure relief section 130.
[0054] Based on the same inventive concept, corresponding to any of the above embodiments, this application also provides a directional pressure relief soft-pack battery module, such as... Figure 6 As shown ( Figure 5 This is a side view of a directional pressure relief pouch battery module in one embodiment; the corresponding front view can be found in the reference diagram. Figure 4 The cross-sectional view of a single battery cell 10 in the directional pressure relief pouch battery of the illustrated embodiment can be found in the following example. Figure 2), the directional pressure relief soft-pack battery module comprises at least two battery units 10 in any of the above embodiments and at least one set of pressure devices 20, wherein:
[0055] The pressure devices 20 are arranged around all the battery units 10 and are used to apply an acting force directed to the inside of the battery units 10 to the battery units 10. The pressure devices 20 play a restraining role and can reduce the deformation degree of the battery when the battery is in thermal runaway, thereby improving the safety of the battery. Meanwhile, a plurality of batteries are restrained by one pressure device 20, which can reduce the overall volume of the battery module.
[0056] In the direction from the inside of the battery unit 10 to the outside of the battery unit 10, the pressure devices 20 do not overlap with the pressure relief part 130, which further ensures that the gas generated inside the battery can preferentially rush out through the pressure relief part 130 when the battery is in thermal runaway.
[0057] The directional pressure relief soft-pack battery module provided by the embodiments of the present disclosure can reduce the deformation degree of the battery when the battery is in thermal runaway by arranging the pressure devices 20, and further ensure that the gas generated inside the battery can preferentially rush out through the pressure relief part 130, thereby realizing directional pressure relief of the battery and improving the safety of the battery.
[0058] In specific implementation, the acting force directed to the inside of the battery unit 10 applied by the pressure devices 20 to the battery unit 10 can be 0.001 MPA to 10 MPa, which can be determined according to the specific model and size of the battery, and is not limited here.
[0059] In specific implementation, the pressure devices 20 can be metal ties, for example, metal materials such as stainless steel, aluminum, carbon steel, etc. can be used as a part of the tie to prevent the tie from being damaged when the battery expands, thereby improving the connection reliability. The pressure devices 20 can also be ties made of plastic materials, for example, non-metal materials such as PET plastic, thereby saving costs.
[0060] It can be understood that the pressure devices 20 in the drawings of the embodiments of the present disclosure are only used to define the positional relationship with the battery units 10, and are not limited to an integral structure. In other embodiments, the pressure devices 20 can be composed of a plurality of components, for example, the pressure devices 20 can include a first clamping plate and a second clamping plate located on both sides of the battery unit 10, respectively, and the first clamping plate and the second clamping plate are connected by a connecting member such as a screw, and apply an acting force directed to the inside of the battery unit 10 to the battery unit 10.
[0061] In some embodiments, as shown in Figure 6 One directional pressure relief soft-pack battery module comprises at least two sets of pressure devices 20, and at least one pressure relief part 130 is located between the two sets of pressure devices 20, which further ensures that the gas generated inside the battery can preferentially rush out through the pressure relief part 130 when the battery is in thermal runaway.
[0062] The directional pressure relief pouch battery module of the above embodiments includes the directional pressure relief pouch battery of any of the above embodiments, and has the beneficial effects of the corresponding embodiments, which are not repeated here.
[0063] It should be noted that, in this document, the terms "first", "second", and the like are used merely to distinguish one entity or action from another, and do not necessarily require or imply any actual such relationship or order between such entities or actions. Also, the terms "comprises", "comprising", or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by an "comprising" statement is not excluded from a process, method, article, or apparatus that includes the element, even if the same process, method, article, or apparatus also includes other like elements.
[0064] The above merely provides specific embodiments of the present disclosure, enabling those skilled in the art to understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the above-described embodiments, but will conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A directional pressure relief soft-pack battery, characterized in that, The battery cell comprises a packaging film, at the edge of the battery cell, two layers of the packaging film form a packaging side edge, and at least one pressure relief part is included on the packaging side edge; In a first direction, the width of the packaging side edge at the location of the pressure relief part is less than the width of the packaging side edge at a location other than the pressure relief part; The first direction points from the center of the battery cell to the packaging side edge where the pressure relief part is located, and is perpendicular to the thickness direction of the packaging film.
2. The oriented pressure relief pouch cell of claim 1, wherein, In the first direction, the width of the packaging side edge at the location of the pressure relief part is between 1.5 mm and 10 mm.
3. The oriented pressure relief pouch cell of claim 1, wherein, In a second direction, the length of the pressure relief part is between 5 mm and 100 mm; The second direction is perpendicular to the first direction and the thickness direction of the packaging film.
4. The oriented pressure relief pouch cell of claim 1, wherein, Two to six pressure relief parts are included on one battery cell.
5. The oriented pressure relief pouch cell of claim 1, wherein, The pressure relief parts on one battery cell are located on one packaging side edge; Alternatively, The pressure relief parts on one battery cell are located on opposite two packaging side edges respectively; Alternatively, The pressure relief parts on one battery cell are located on adjacent two packaging side edges respectively; Alternatively, The pressure relief parts on one battery cell are located on adjacent three packaging side edges respectively.
6. The oriented pressure relief pouch cell of claim 1, wherein, The packaging film comprises a cast polypropylene film layer; The deformation amount of the cast polypropylene film layer at at least part of the location of the pressure relief part is less than the deformation amount of the cast polypropylene film layer at a location other than the pressure relief part.
7. The oriented pressure relief pouch cell of claim 6, wherein, The deformation amount of the cast polypropylene film layer at at least part of the location of the pressure relief part is between 3% and 20%.
8. The oriented pressure relief pouch cell of claim 1, wherein, Further comprising at least one set of pressure devices; The pressure devices are arranged around the battery cell and are used to apply a force directed to the inside of the battery cell to the battery cell; In a direction from the inside of the battery cell to the outside of the battery cell, the pressure devices do not overlap with the pressure relief part.
9. The oriented pressure relief pouch cell of claim 8, wherein, At least two sets of pressure devices are included, and at least one pressure relief part is located between the two sets of pressure devices.
10. A directional pressure relief pouch battery module, characterized by, At least two battery cells according to any one of claims 1 to 7 and at least one set of pressure devices are included, wherein: The pressure devices are arranged around all the battery cells and are used to apply a force directed to the inside of the battery cell to the battery cells; In a direction from the inside of the battery cell to the outside of the battery cell, the pressure devices do not overlap with the pressure relief part.