Battery cell, battery, and electrical device

Abstract

The present application discloses a battery cell, a battery, and an electrical device. The battery cell comprises a housing and an exhaust assembly, the housing having a wall portion. The exhaust assembly is disposed on the wall portion, the exhaust assembly comprising a one-way valve and / or a gas-permeable membrane assembly, the gas-permeable membrane assembly comprising a gas-permeable membrane, and the exhaust assembly discharging gas in the housing. A first weak strength area is disposed on the wall portion, the first weak strength area being arranged along a circumferential direction of the exhaust assembly. By means of this type of configuration, gas in the battery cell housing can be discharged out of the housing in a timely manner, and when the internal pressure or temperature of the battery cell reaches a threshold value, the pressure in the battery cell can be released.

Description

Battery cells, batteries and electrical equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202323527461.8, filed on December 22, 2023, entitled “Battery Cell, Battery and Electrical Equipment,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of new energy technology, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0004] As global energy and environmental issues continue to intensify, new energy, as one of the areas of sustainable development, is developing rapidly. Batteries are becoming more and more widely used as a new energy source, and there are high requirements for their reliability and service life. During the charging and discharging process of battery cells, the internal pressure of the battery cells will increase due to the generation of gas inside the battery cells. If the generated gas is not discharged in time, when the internal pressure or temperature of the battery cells reaches a threshold, it is easy to cause dangers such as explosion. The above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0005] The main technical problem solved by the present application is to provide a battery cell, a battery and an electrical device, which can discharge the gas inside the battery cell shell to the outside of the shell in time, and release the pressure inside the battery cell when the internal pressure or temperature of the battery cell reaches a threshold.

[0006] To address the aforementioned technical issues, this application employs a technical solution: providing a battery cell comprising a housing and a vent assembly, the housing having a wall portion; a vent assembly disposed within the wall portion, the vent assembly comprising a one-way valve and / or a breathable membrane assembly, the breathable membrane assembly comprising a breathable membrane, the vent assembly being used to exhaust gas from within the housing; and a first weakened zone disposed on the wall portion, the first weakened zone being arranged along the circumference of the vent assembly. This arrangement allows for timely exhaust of gas from within the battery cell housing to the exterior of the housing, while also releasing pressure within the battery cell when the internal pressure or temperature reaches a threshold.

[0007] According to one embodiment of the present application, the first strength weak area includes a first thickness weak area. This arrangement is helpful in simplifying the manufacturing process.

[0008] According to one embodiment of the present application, the first weak zone comprises a first groove that is recessed relative to the surface of the wall portion, and the first groove is arranged around the exhaust component. This arrangement helps to simplify the manufacturing process.

[0009] According to one embodiment of the present application, the wall portion has an outer surface and an inner surface disposed opposite each other, with the outer surface facing the exterior of the housing and the inner surface facing the interior of the housing; the first groove is recessed relative to the outer surface; and / or the first groove is recessed relative to the inner surface. This arrangement further reduces the strength of the first weak zone.

[0010] According to one embodiment of the present application, the first weak zone includes a plurality of second grooves that are recessed relative to the surface of the wall portion, and the plurality of second grooves are spaced apart in the circumferential direction of the exhaust assembly. This arrangement helps simplify the manufacturing process.

[0011] According to one embodiment of the present application, the first weak zone further comprises notches arranged at the bottom of the first groove and / or the second groove. This arrangement is conducive to further reducing the strength of the first weak zone.

[0012] According to one embodiment of the present application, the wall portion includes a wall body and a sunken portion. The wall body has an outer surface and an inner surface disposed opposite each other, with the outer surface facing the exterior of the housing and the inner surface facing the interior of the housing. The sunken portion is connected to the wall body and protrudes from the inner surface. The first weak zone is disposed on the sunken portion. This arrangement further reduces the strength of the first weak zone.

[0013] According to one embodiment of the present application, a first vent hole is provided on the wall portion, connecting the interior of the housing with the exterior of the housing, and the vent assembly includes a one-way valve that covers the first vent hole. This arrangement helps balance the sealing and venting performance of the battery cell.

[0014] According to one embodiment of the present application, the wall portion has an outer surface and an inner surface disposed opposite each other, with the outer surface facing the exterior of the housing and the inner surface facing the interior of the housing. A one-way valve is disposed on the outer surface, and the one-way valve includes a valve body, at least a portion of which protrudes from the outer surface. This arrangement facilitates assembly of the one-way valve.

[0015] According to one embodiment of the present application, a second weak zone is provided on the valve body. The actuation pressure of the second weak zone is greater than the valve opening pressure of the one-way valve, and the actuation pressure of the second weak zone is less than the actuation pressure of the first weak zone. This arrangement can achieve the effect of discharging gas from the battery cells in a layered manner when the internal pressure of the battery cells is excessive.

[0016] According to one embodiment of the present application, the valve body has a valve cavity within it. The valve body includes a valve seat and a valve cover. The valve cover includes a cover top wall and a cover side wall connected to the cover top wall. The cover top wall, the cover side wall, and the valve seat enclose the valve cavity. The second weak zone is provided on the cover side wall. This arrangement can reduce damage to the battery casing caused by valve body fracture.

[0017] According to one embodiment of the present application, the second weak zone includes a plurality of third grooves provided on the side wall of the cover. This arrangement can reduce the damage to the battery housing caused by the rupture of the valve body.

[0018] According to one embodiment of the present application, the one-way valve includes a valve body and a valve core. The valve body defines a valve cavity. The valve body is provided with an air inlet and an air outlet. The air inlet connects the valve cavity with the interior of the housing, while the air outlet connects the valve cavity with the exterior of the housing. The valve core is disposed within the valve cavity and blocks the air inlet. The valve core is configured to open the air inlet in response to gas inside the housing, thereby releasing gas from the battery cell. This arrangement facilitates the discharge of gas.

[0019] In one embodiment, the valve body includes a valve seat and a valve cover. The valve cover includes a cover top wall and a cover side wall connected to the cover top wall. The cover top wall, the cover side wall and the valve seat enclose a valve cavity. The valve seat is provided with an air inlet, and the valve cover is provided with an air outlet. This facilitates the discharge of gas.

[0020] In one embodiment, the valve seat has a first through hole penetrating the valve seat, and the air inlet is the first through hole. In this way, the discharge of gas is facilitated.

[0021] In one embodiment, the cover sidewall has a second through hole penetrating the cover sidewall, and the gas outlet is the second through hole. In this way, the gas is easily discharged.

[0022] In one embodiment, the second through hole extends to the end of the cover side wall in a direction away from the cover top wall; in this way, the discharge of gas is facilitated.

[0023] In one embodiment, there are multiple second through holes, and the multiple second through holes are spaced apart in the circumferential direction of the side wall, thereby facilitating the discharge of gas.

[0024] In one embodiment, a first guide post is protruding from the side of the lid top wall facing the valve seat, and a third through hole is formed on the lid top wall, penetrating the lid top wall and the first guide post, or a third through hole is formed on the lid top wall, and the gas outlet is the third through hole. This facilitates gas discharge.

[0025] In one embodiment, the valve cover further comprises a flange wall, the cover side wall connects the cover top wall and the flange wall, the flange wall extends relative to the cover side wall toward a side away from the valve cavity, and the flange wall is connected to the valve seat. In this way, the assembly of the one-way valve is facilitated.

[0026] In one embodiment, a first recessed groove is provided on the side of the valve seat facing the valve cover, which is recessed relative to the surface of the valve seat. At least a portion of the flange wall is accommodated in the first recessed groove and connected to the valve seat. This improves the connection strength while reducing the installation height of the one-way valve.

[0027] In one embodiment, the surface of the flange wall facing the top wall of the cover is flush with the surface of the valve seat facing the valve cover; or the surface of the flange wall facing the top wall of the cover is lower than the surface of the valve seat facing the valve cover. In this way, the installation height of the one-way valve can be reduced.

[0028] In one embodiment, the flange wall is welded to the valve seat; wherein, along the circumference of the cover sidewall, at least a portion of the first weld mark between the flange wall and the valve seat is offset from the second through hole in the cover sidewall. This reduces damage to the valve core component caused by high temperatures during the welding process.

[0029] In one embodiment, the valve core includes an elastic member and a blocking member. The elastic member is disposed within the valve cavity. The blocking member is movably disposed within the valve cavity. The blocking member is configured to block the air inlet under the action of the elastic member and to open the air inlet under the action of gas within the housing. This facilitates the discharge of gas.

[0030] In one embodiment, the blocking member includes a pressing portion and a sealing portion. Along the thickness of the wall, the ends of the elastic member abut against the valve cover and the pressing portion, respectively. The sealing portion is connected to the side of the pressing portion facing away from the valve cover and is used to seal the air inlet. This facilitates the transmission of the elastic force of the elastic member to the blocking member, ensuring the sealing of the one-way valve.

[0031] In one embodiment, the first vent includes a through-hole segment and a first hole segment, which are arranged along the thickness of the wall. The through-hole segment connects the interior of the housing with the exterior of the housing. The first hole segment is located on the side of the through-hole segment facing away from the interior of the housing. The aperture of the first hole segment is larger than the aperture of the through-hole segment. The one-way valve is at least partially accommodated in the first hole segment. The valve body of the one-way valve faces the exterior of the housing, and at least a portion of the valve body protrudes from the outer surface of the wall. This facilitates assembly of the one-way valve.

[0032] In one embodiment, the first hole segment includes a circumferential hole side surface, and the valve seat is provided with a first step surface and a second step surface on the side facing the valve cover. The first step surface is closer to the valve cover than the second step surface, and the outer circumferential surface of the second step is welded to the hole side surface. This method can improve assembly stability.

[0033] In one embodiment, the wall portion includes a pressure relief mechanism and a pressure relief hole, the pressure relief hole communicating with the interior and exterior of the housing. The pressure relief mechanism includes a pressure relief plate that covers the pressure relief hole, and a first weakened area is provided on the pressure relief plate. The pressure relief mechanism is configured to activate and release internal pressure in the battery cell when thermal runaway occurs, with the activation pressure of the pressure relief mechanism being greater than the activation pressure of the first weakened area. This arrangement enables the gas within the battery cell to be discharged in a layered manner when excessive internal pressure in the battery cell occurs.

[0034] The pressure relief plate is provided with a second vent hole, which connects the interior of the housing to the exhaust assembly. The exhaust assembly includes a one-way valve or a breathable membrane assembly, which is installed on the pressure relief plate and covers the second vent hole. This arrangement helps balance the sealing and exhaust performance of the battery cells.

[0035] The wall portion is provided with a first vent hole, which connects the interior of the housing with the exterior of the housing. The vent assembly includes a breathable membrane assembly, which covers the first vent hole. This arrangement helps balance the sealing and venting performance of the battery cell.

[0036] In one embodiment, the breathable membrane assembly includes a breathable membrane and a connector. The connector is provided with a first breathable hole. The breathable membrane is disposed on the connector and covers the first breathable hole. The breathable membrane is configured to allow gas within the battery cell to pass through the breathable membrane and escape. This arrangement improves connection strength and reduces the risk of deformation of the breathable membrane.

[0037] In one embodiment, the connector has a first annular surface that is recessed relative to the connector surface, the first annular surface is disposed around the first vent hole, and the breathable membrane is disposed on the first annular surface. This helps reduce the installation height of the breathable membrane assembly.

[0038] In one embodiment, the breathable membrane assembly further includes a backing member disposed between the breathable membrane and the connector; the backing member has a higher air permeability than the breathable membrane. The backing member provides support for the breathable membrane and reduces the risk of deformation of the breathable membrane.

[0039] In one embodiment, the connector further comprises a second annular platform recessed relative to the surface of the connector, the second annular platform surrounding the first vent hole, and the backing member is disposed on the second annular platform. In this manner, the installation height of the breathable membrane assembly can be reduced.

[0040] In one embodiment, the connecting piece is a metal piece, which can improve the connection strength between the connecting piece and other components.

[0041] In one embodiment, the breathable membrane is arranged on the side of the connector facing the interior of the housing, and the breathable membrane covers the first breathable hole. This arrangement can reduce damage to the breathable membrane from the external environment.

[0042] In one embodiment, the wall portion has a first sunken platform that is recessed relative to the surface of the wall portion, the first sunken platform being arranged around the second exhaust hole, and the breathable membrane assembly is at least partially located on the first sunken platform. In this way, the installation height of the breathable membrane assembly can be reduced.

[0043] In one embodiment, the housing includes a shell and an end cap. The shell defines an opening within the housing for accommodating the electrode assembly. The end cap seals the opening. The end cap is a wall, or the shell includes a wall, or the wall is located at the top of the housing when the battery cell is in a placed state. This facilitates gas discharge.

[0044] To solve the above technical problems, another technical solution adopted by the present application is to provide a battery comprising the above battery cells, which has at least the same advantages as the battery cells.

[0045] To solve the above technical problems, another technical solution adopted by the present application is to provide an electrical device comprising the above battery, which has at least the same advantages as the battery.

[0046] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0048] FIG1 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments;

[0049] FIG2 is a schematic diagram of a partially exploded structure of a battery cell according to one or more embodiments;

[0050] FIG3 is a schematic diagram of a partial cross-sectional structure of a battery cell 20 according to one or more embodiments;

[0051] FIG4 is a schematic diagram of a partial cross-sectional structure of a battery cell 20 according to one or more embodiments;

[0052] FIG5 is a front view of a one-way valve according to one or more embodiments;

[0053] FIG6 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0054] FIG7 is a schematic diagram of a one-way valve according to one or more embodiments;

[0055] FIG8 is a schematic diagram of a partially exploded structure of a battery cell according to one or more embodiments;

[0056] FIG9 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0057] FIG10 is a front view of a one-way valve according to one or more embodiments;

[0058] FIG11 is a schematic diagram of an exploded structure of a one-way valve according to one or more embodiments;

[0059] FIG12 is a schematic cross-sectional view of a one-way valve according to one or more embodiments;

[0060] FIG13 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0061] FIG14 is a schematic diagram of a cross-sectional structure of a wall portion according to one or more embodiments;

[0062] FIG15 is a schematic cross-sectional view of a breathable membrane assembly according to one or more embodiments;

[0063] FIG16 is a schematic cross-sectional view of a breathable membrane assembly 40 according to one or more embodiments;

[0064] FIG17 is a schematic diagram of a partial cross-sectional structure of a battery cell 20 according to one or more embodiments;

[0065] FIG18 is a schematic diagram of a partial cross-sectional structure of a battery cell 20 according to one or more embodiments;

[0066] FIG19 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments;

[0067] FIG20 is a schematic diagram of an exploded structure of a battery according to one or more embodiments;

[0068] FIG21 is a schematic structural diagram of a vehicle according to one or more embodiments.

[0069] In the accompanying drawings: 1000, vehicle; 300, motor; 200, controller; 100, battery; 10, housing; 11, first part; 12, second part; 20, battery cell; 21, wall; 21, end cap; 21a, outer surface; 21b, inner surface; 212, first weak zone; 212a, first groove; 210, wall body; 210a, sinking portion; 291, first vent hole; 292, second vent hole; 22, housing; 23, electrode assembly; 24, insulating member; 25, electrode terminal; 280, through-hole section; 281, first hole section; 30, one-way valve; 31, valve body; 311, valve seat; 3111, first through-hole; 3112, first sinking groove; 311b, first step surface; 311c, second step surface; 3119, second weak zone; 3 12. Valve cover; 3121. Top wall of cover; 31211. First guide post; 31212. Third through hole; 3122. Side wall of cover; 31221. Second through hole; 31222. Flanged wall; 31222a. Connecting surface; 313. Valve cavity; 313a. Air inlet; 313b. Air outlet; 32. Valve core; 321. Blocking member; 322. Elastic member; 40. Breathable membrane assembly; 41. Breathable membrane; 42. Metal part; 491. First breathable hole; 43. Backing member; 70. Pressure relief mechanism; 71. Pressure relief sheet; 60. Protective patch; 601. First avoidance hole; 602. Second avoidance hole; 603. Information collection hole; 90. Exhaust assembly; T1. First annular table; T2. Second annular table; T3. Transition surface; S1. First sink; W1. First weld mark. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical solution and effect of this application clearer and more specific, the following embodiments of the technical solution of this application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of this application and are therefore only examples and are not intended to limit the scope of protection of this application.

[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0072] In the description of the embodiments of the present application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), similarly, "multiple groups" refers to more than two (including two), and "multiple pieces" refers to more than two (including two), unless otherwise clearly and specifically defined.

[0073] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0074] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0075] Amounts, ratios, and other numerical values ​​are presented herein in a range format. It should be understood that such range format is used for convenience and brevity and should be interpreted flexibly to include not only the values ​​explicitly specified as limits of the range, but also all individual values ​​or sub-ranges encompassed within the range, as if each value and sub-range were explicitly specified.

[0076] In the description of the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and do not constitute any limitation on this application.

[0077] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0078] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0079] Batteries have a wide range of applications in the new energy sector, primarily in electric vehicles, energy storage systems, and renewable energy. In the electric vehicle sector, higher performance features such as longer driving range and faster charging are gradually being achieved. In energy storage systems, batteries are widely used for large-scale and distributed energy storage. They can balance grid loads, store renewable energy such as solar and wind power, and release the stored energy during peak periods. Furthermore, small rechargeable batteries are widely used in applications such as wearable devices, drones, and smart homes.

[0080] During the charge and discharge process of battery cells, some side reactions will produce gases. If the gases generated by the battery cells are not discharged in a timely manner, the internal pressure of the battery cells will increase. Excessive internal pressure will have a negative impact on the performance and appearance of the battery cells. For example, in severe cases, it will have a destructive impact on the performance and appearance of the battery cells, such as leakage, bulging, increased internal resistance of the battery cells, and shortened discharge time and cycle life. In addition, there are some abnormal operations of battery cells during use, including overcharging, over-discharging, and internal failures. In this case, the chemical reaction inside the battery cells may be uncontrolled, accompanied by a violent release of gas, and even cause thermal runaway of the battery cells. Battery cell thermal runaway refers to a chain reaction phenomenon triggered by various factors. The large amount of heat and harmful gases emitted by thermal runaway can cause the battery cells to catch fire and explode.

[0081] Based on the above considerations, an embodiment of the present application provides a battery cell, on which an exhaust assembly is provided. The exhaust assembly can timely discharge the gas inside the battery cell to maintain a stable internal pressure of the battery cell.

[0082] Please refer to Figure 1, which shows an exploded view of a battery cell according to one or more embodiments. A battery cell 20 is the smallest unit of a battery. As shown in Figure 1, a battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0083] The end cap 21 refers to a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the housing 22 to match the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as an aluminum alloy). In this way, the end cap 21 is less likely to deform when squeezed or collided, so that the battery cell 20 can have a higher structural strength and improved safety performance. Functional components such as electrode terminals 25 can be provided on the end cap 21. The electrode terminals 25 can be used to electrically connect to the electrode assembly 23 to output or input electrical energy from the battery cell 20. Exemplarily, the battery cell 20 is provided with two electrode terminals 25, and both electrode terminals 25 are mounted on the end cap 21. The two electrode terminals 25 are respectively used to electrically connect to the two tabs of opposite polarity of the electrode assembly 23 to respectively output or input the positive and negative electrodes of the battery cell 20. The end cap 21 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and plastic, and this is not particularly limited in the present embodiment. In some embodiments, an insulating member 24 can be disposed inside the end cap 21 to isolate the electrical connection components within the housing 22 from the end cap 21, thereby reducing the risk of short circuits. Exemplary materials include plastic, rubber, and the like.

[0084] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. Specifically, the end cap 21 and housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be enclosed, the end cap 21 is placed over the housing 22. The housing 22 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, or a hexagonal prism. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the electrode assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this.

[0085] The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 23 may be contained in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab. The positive and negative electrode tabs may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery cell, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0086] Please refer to Figures 1 and 2 . Figure 2 is a schematic diagram of a partially exploded structure of a battery cell according to one or more embodiments. According to some embodiments of the present application, the present application discloses a battery cell 20, which includes a housing and a vent assembly 90. The housing has a wall portion 21, and the vent assembly 90 is disposed on the wall portion 21. The vent assembly 90 includes a one-way valve 30 and / or a breathable membrane assembly 40. The breathable membrane assembly 40 includes a breathable membrane 41. The vent assembly 90 is used to exhaust gas from the interior of the housing. The wall portion 21 is provided with a first weak zone 212, which is arranged along the circumference of the vent assembly 90.

[0087] The exhaust assembly 90 including the one-way valve 30 and / or the breathable membrane assembly 40 means that the exhaust assembly 90 may include the one-way valve 30 alone, the breathable membrane assembly 40 alone, or both. When the exhaust assembly 90 includes both the one-way valve 30 and the breathable membrane assembly 40, the one-way valve 30 and the breathable membrane assembly 40 may be arranged in series, i.e., when gas is discharged through the one-way valve 30, it also flows through the breathable membrane assembly 40. The one-way valve 30 and the breathable membrane assembly 40 may also be arranged in parallel, i.e., gas may be discharged through the one-way valve 30 and the breathable membrane assembly 40, respectively. FIG1 illustrates the exhaust assembly 90 as including the one-way valve 30. By providing the exhaust assembly 90 on the battery cell 20, the internal gas of the battery cell 20 can be discharged to the outside of the outer shell of the battery cell 20 in time, so that the air pressure inside the battery cell 20 is maintained at a normal level, which can improve the safety performance of the battery cell 20 and greatly increase the life of the battery cell 20.

[0088] The first weak zone 212 is a region of relatively lower strength relative to other regions of the wall 21. If the wall 21 is affected by external forces or other factors, it is prone to fracture or other damage occurring preferentially at the first weak zone 212. By providing the first weak zone 212 on the battery cell 20, when the internal pressure of the battery cell 20 is excessive or the temperature reaches a threshold, the wall 21 can fracture at the first weak zone 212, thereby promptly releasing the pressure within the battery cell 20. In other words, the solution provided in this application provides a vent assembly 90 on the battery cell 20. During normal use of the battery cell 20, gas generated within the battery cell 20 housing can be discharged through the vent assembly 90. However, when thermal runaway or excessive internal pressure occurs within the battery cell 20, the wall 21 of the battery cell 20 can fracture at the first weak zone 212 to release gas, etc., within the battery cell 20.

[0089] In one embodiment, the first weakened region 212 comprises a first thickness weakened region. Specifically, this region may be relatively thinner than other regions of the wall portion 21, reducing the thickness to reduce strength. In other embodiments, the first weakened region 212 may be constructed by selecting materials of varying strengths, such as materials with relatively low strength.

[0090] According to some embodiments of the present application, the outer shell includes an end cover 21 and a shell 22, and the wall portion may be the wall of the end cover 21 or the wall of the shell 22. That is, the exhaust assembly 90 may be arranged on the end cover 21 or on the shell 22. In other words, the wall portion for mounting the exhaust assembly 90 may be the end cover 21 of the outer shell or a wall of the shell 22 of the outer shell. Exemplarily, the wall portion is the end cover 21. Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the wall portion may also be the bottom wall of the shell 22 and the end cover 21, and the wall portion may also be the side wall of the shell 22 and the end cover 21 adjacent to and connected to each other. The following will take the wall portion as the wall of the end cover 21 as an example to illustrate the present application, but this should not limit the present application.

[0091] Please refer to Figures 1, 2, and 3. Figure 3 is a schematic diagram of a partial cross-sectional structure of a battery cell 20 according to one or more embodiments. In one embodiment, the first weak zone 212 includes a first groove 212a that is recessed relative to the surface of the wall portion 21. The first groove 212a is disposed around the exhaust assembly 90. By providing the first groove 212a on the wall portion 21, the thickness of the wall portion 21 in the area where the first groove 212a is located can be reduced, thereby weakening the wall portion 21 in this area, thereby weakening the wall portion 21 in this area.

[0092] As shown in FIG2 , the first groove 212 a may be an annular groove surrounding the exhaust assembly 90. The first groove 212 a may be a notched groove formed by etching or other methods. In other embodiments, the first groove 212 a may be a non-closed annular groove, that is, the first groove 212 a does not necessarily have to be completely closed in the circumferential direction, and may also be a groove in the shape of two-thirds of a circle, or a groove in the shape of three-quarters of a circle.

[0093] In one embodiment, the first weakened region 212 includes a plurality of second grooves (not shown) recessed relative to the surface of the wall portion 21. The plurality of second grooves are spaced apart circumferentially around the exhaust assembly 90. Alternatively, the annular first groove can be interrupted to form a plurality of second grooves. In this embodiment, the provision of discontinuous grooves can be used to weaken the thickness of the wall portion 21 in this region, thereby reducing the strength of the wall portion 21 in this region.

[0094] In one embodiment, the first weak zone further includes a notch 212b disposed at the bottom of the first groove 212a and / or the second groove. As shown in FIG3 , the bottom of the first groove 212a is provided with a notch 212b. This arrangement further reduces the strength of the first groove 212a, facilitating breakage of the wall portion 21 at this location.

[0095] Please refer to Figure 4, which is a partial cross-sectional view of a battery cell 20 according to one or more embodiments. In one embodiment, the wall portion 21 has an outer surface 21a and an inner surface 21b disposed opposite each other, with the outer surface 21a facing the exterior of the housing and the inner surface 21b facing the interior of the housing. The first groove 212a is recessed relative to the outer surface 21a of the wall portion 21, and / or the first groove 212a is recessed relative to the inner surface 21b of the wall portion 21.

[0096] The first groove 212a can be provided on both the inner and outer sides of the wall portion 21; the first groove 212a can be provided only on the outer surface 21a of the wall portion 21; or the first groove 212a can be provided only on the inner surface 21b of the wall portion 21. As shown in Figure 4, the first groove 212a is provided on both the outer surface 21a and the inner surface 21b of the wall portion 21. When the first groove 212a is provided on both sides, the orthographic projections of the first grooves 212a on both sides on the wall portion 21 can be set to at least partially overlap. Through this arrangement, the thickness of the wall portion 21 can be reduced from both sides, reducing the thickness of the wall portion 21 where the first groove 212a is provided, thereby achieving a thinner thickness in this area. When the internal pressure of the battery cell 20 is too high, the wall portion 21 is more likely to break at the first groove 212a. When the first groove 212a is provided on both the inner and outer sides of the wall portion 21, the notch 212b may be provided at the bottom of the first groove 212a on only one side. Alternatively, the notch 212b may be provided at the bottom of the first groove 212a on both sides. As shown in FIG4 , the notch 212b is provided at the bottom of the first groove 212a located on the outer side of the wall portion 21.

[0097] Continuing with Figure 4 , the wall portion 21 includes a main wall body 210 and a sunken portion 210a. The main wall body 210 has an outer surface 21a and an inner surface 21b disposed opposite each other, with the outer surface 21a facing the exterior of the housing and the inner surface 21b facing the interior of the housing. The sunken portion 210a is connected to the main wall body 210 and protrudes from the inner surface 21b. A first weak zone 212 is disposed on the sunken portion 210a.

[0098] The wall portion 21 may be stamped to form a concave sunken portion 210a. This arrangement can reduce the strength of the area after stamping and reduce the space occupied by the exhaust assembly 90 in the height direction of the battery cell 20.

[0099] Please refer to Figures 1, 2, 3 and 4. In one embodiment, the wall portion 21 is provided with a first exhaust hole 291, which connects the inside of the shell with the outside of the shell. The exhaust component 90 includes a one-way valve 30, and the one-way valve 30 covers the first exhaust hole 291. In this embodiment, the one-way valve 30 is used as the exhaust component 90. When the internal pressure of the battery cell 20 reaches a predetermined pressure, the valve opens to release air. As the internal pressure of the battery cell 20 decreases, the one-way valve 30 closes again to achieve the sealing of the battery cell 20. In other words, when the one-way valve 30 is used to exhaust air, it is actually intermittent exhaust. In this way, the battery cell 20 does not need to be in the exhaust state all the time. The sealing of the battery cell 20 is maintained to reduce the intrusion of external water vapor.

[0100] In one embodiment, at least a portion of the one-way valve 30 is received in the first exhaust hole 291 .

[0101] Referring to Figures 1, 2, 3, and 4, in one embodiment, the wall portion 21 has an outer surface 21a and an inner surface 21b disposed opposite each other, with the outer surface 21a facing the exterior of the housing and the inner surface 21b facing the interior of the housing. A one-way valve 30 is disposed on the outer surface 21a and includes a valve body 31, at least a portion of which protrudes from the outer surface 21a. This arrangement facilitates assembly of the one-way valve 30.

[0102] Please refer to Figures 5 and 6 . Figure 5 is a front view of a one-way valve according to one or more embodiments. Figure 6 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments. In one embodiment, the valve body 31 of the one-way valve 30 is provided with a second weak zone 3119. The actuation pressure of the second weak zone 3119 is greater than the valve opening pressure of the one-way valve 30, and the actuation pressure of the second weak zone 3119 is less than the actuation pressure of the first weak zone 212.

[0103] Among them, the actuating pressure of the first strength weak zone 212 refers to the pressure that can cause the wall portion 21 to break from the first strength weak zone 212; similarly, the actuating pressure of the second strength weak zone 3119 refers to the pressure that can cause the one-way valve 30 to break from the second strength weak zone 3119.

[0104] In some embodiments, the actuation pressure of the second weak zone 3119 is greater than the opening pressure of the one-way valve 30. That is, the pressure of the gas inside the battery cell 20 housing that causes the one-way valve 30 to rupture at the second weak zone 3119 is greater than the pressure of the gas inside the housing that opens the one-way valve 30. When the internal pressure of the battery cell 20 is excessive or thermal runaway occurs, the gas inside the housing of the battery cell 20 will rapidly surge, breaking through the valve body 31 of the one-way valve 30 (as shown in FIG. 7 , which is a schematic diagram of a one-way valve according to one or more embodiments) to release pressure. However, during normal use, when the gas generated inside the housing 21 of the battery cell 20 reaches a threshold, the one-way valve 30 can be opened, but the gas cannot break through the valve body 31 of the one-way valve 30.

[0105] The actuation pressure of the second weak zone 3119 is lower than the actuation pressure of the first weak zone 212. That is, the pressure at which the gas inside the battery cell 20 casing causes the one-way valve 30 to rupture at the second weak zone 3119 is lower than the pressure at which the gas inside the casing causes the wall 21 to rupture at the first weak zone 212. When the internal pressure of the battery cell 20 is excessive or thermal runaway occurs, the gas inside the casing of the battery cell 20 will rapidly surge, preferentially breaking through the valve body 31 of the one-way valve 30 to release pressure. If this still fails to meet the pressure relief requirement, as the pressure increases, it may further break through the wall 21 to release pressure. During normal use, the gas generated inside the casing 21 of the battery cell 20 can open the one-way valve 30 when it reaches a threshold, but it cannot break through the valve body 31 or wall 21 of the one-way valve 30.

[0106] This arrangement is equivalent to designing a multi-stage control valve. During normal use of the battery cell 20, the one-way valve 30 is used for exhaust. At this time, the one-way valve 30 and the wall 21 are both intact. If the internal air pressure of the battery cell 20 suddenly increases and the pressure is too high, the valve body 31 of the one-way valve 30 can be broken through to release the pressure. At this time, the wall 21 is intact. If the pressure still cannot be significantly relieved, as the pressure increases, the wall 21 can continue to be broken through to release the pressure. Through the multi-stage arrangement, the gas inside the shell can be discharged to the outside of the shell in a timely manner, so that the air pressure inside the shell is not too high, reducing the risk of premature damage to the wall 21, and significantly improving the life of the battery cell 20.

[0107] In some embodiments, the interior of the valve body 31 has a valve cavity 313, the valve body 31 includes a valve seat 311 and a valve cover 312, the valve cover 312 includes a cover top wall 3121 and a cover side wall 3122 connected to the cover top wall 3121, the cover top wall 3121, the cover side wall 3122 and the valve seat 311 enclose a valve cavity 313, and a second strength weak area 3119 is set on the cover side wall 3122.

[0108] In some embodiments, the second weak zone 3119 includes a plurality of third grooves 3119 a disposed on the cover sidewall 3122 .

[0109] By providing the third groove 3119a on the cover side wall 3122, the thickness of the cover side wall 3122 in the area where the third groove 3119a is located can be reduced, thereby achieving a weaker thickness in the area and further achieving a weaker strength in the area.

[0110] In one embodiment, the third groove 3119a is located on the side of the cover sidewall 3122 facing the valve cavity 313; and / or the third groove 3119a is located on the side of the cover sidewall 3122 facing away from the valve cavity 313. In other words, the third groove 3119a can be provided on both the inside and outside of the cover sidewall 3122. Alternatively, the third groove 3119a can be provided only on the inside of the cover sidewall 3122, or only on the outside of the cover sidewall 3122. When the third groove 3119a is provided on both the inside and outside, the orthographic projections of the third grooves 3119a on both sides on the cover sidewall 3122 can be arranged to at least partially overlap. This arrangement allows the cover sidewall 3122 to be thinned from both sides, reducing the thickness of the cover sidewall 3122 where the third groove 3119a is provided, thereby reducing the thickness and making it more susceptible to breaking when subjected to pressure.

[0111] In one embodiment, the cover sidewall 3122 has a second through-hole 31221 extending through it, and the third groove 3119a is disposed on the connecting arm between two adjacent second through-holes 31221. Multiple second through-holes 31221 may be provided, spaced apart circumferentially around the cover sidewall 3122. The provision of the second through-holes 31221 can eliminate a portion of the cover sidewall 3122, reducing its strength to a certain extent. Furthermore, the provision of the third groove 3119a further enhances the ability of the wall portion 21 to break when subjected to pressure.

[0112] As shown in Figure 5, a third groove 3119a may be provided on the connecting arm between two adjacent second through holes 31221. The third groove 3119a may extend along the circumference of the valve cover 312 and may extend to both ends of the connecting arm.

[0113] In one embodiment, the second area of ​​weakness 3119 comprises a first score groove that is a circumferential groove surrounding the cover sidewall 3122 .

[0114] As shown in Figure 5, due to the provision of the second through hole 31221, the cover sidewall 3122 includes a solid area 3122a and a vent area 3122b in the direction of the axis Y of the valve chamber 313. In the circumferential direction of the valve chamber 313, the cover sidewall 3122 in the vent area 3122b is provided with the second through hole 31221, and the cover sidewall 3122 is discontinuous, while the cover sidewall 3122 in the solid area 3122a is a continuous solid structure. Therefore, a second weak area 3119 can also be provided in the cover sidewall 3122 in the solid area 3122a. Specifically, the second weak area 3119 includes a first notch, which is a circumferential groove in the cover sidewall 3122.

[0115] In other embodiments, discontinuous grooves may be provided along the circumference of the cover sidewall 3122. Specifically, the second weak zone 3119 includes a plurality of second scored grooves spaced apart along the circumference of the cover sidewall 3122. In other words, a plurality of discontinuous grooves may be provided on the cover sidewall 3122 in the solid zone 3122a.

[0116] Referring to Figures 3, 4, and 6, the one-way valve 30 in this application may or may not include the second weak zone 3119. This can be selected as needed. In some embodiments, two types of one-way valves 30 may be provided on a single battery cell 20.

[0117] Referring to Figures 1 and 2 , the wall portion 21 with the first weakened area 212 provides a certain degree of pressure relief, and the one-way valve 30 with the second weakened area 3119 also provides a pressure relief function. Therefore, when this structure is selected, a pressure relief mechanism may not be provided on the battery cell 20. Of course, when both the wall portion 21 with the first weakened area 212 and the one-way valve 30 with the second weakened area 3119 are selected, a pressure relief mechanism may also be provided on the battery cell 20.

[0118] Please refer to Figures 8 and 9 in combination. Figure 8 is a schematic diagram of a partial decomposition structure of a battery cell according to one or more embodiments. Figure 9 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments. In one embodiment, the wall portion 21 includes a pressure relief mechanism 70 and a pressure relief hole 701. The pressure relief hole 701 connects the inside of the shell and the outside of the shell. The pressure relief mechanism 70 includes a pressure relief plate 71. The pressure relief plate 71 covers the pressure relief hole 701. The first strength weak zone 212 is provided on the pressure relief plate 71. The pressure relief mechanism 70 is configured to actuate and release the internal pressure of the battery cell 20 when the battery cell 20 thermally runs away. The actuation pressure of the pressure relief mechanism 70 is greater than the actuation pressure of the first strength weak zone 212.

[0119] The actuation pressure of the pressure relief mechanism 70 is set to be greater than the actuation pressure of the first weak zone 212. With this arrangement, when thermal runaway occurs in the battery cell 20, the gas inside the outer shell of the battery cell 20 will rapidly increase, thereby opening the pressure relief mechanism 70 to relieve pressure. However, during normal use, the gas generated inside the outer shell 21 of the battery cell 20 can be discharged through the exhaust assembly, but the pressure relief mechanism 70 cannot be opened. Furthermore, in the event of thermal runaway, before opening the pressure relief mechanism 70, the exhaust assembly can be destroyed at the first weak zone 212 to provide a certain degree of pressure relief. If the gas pressure inside the battery cell 20 still increases, the pressure relief mechanism 70 can be opened again.

[0120] In one embodiment, the pressure relief plate 71 is provided with a second vent hole 292, which connects the interior of the housing with the vent assembly 90. The vent assembly 90 includes a breathable membrane assembly 40, which is disposed on the pressure relief plate 71 and covers the second vent hole 292. This arrangement allows gases generated within the housing 21 of the battery cell 20 during normal use to be discharged through the breathable membrane assembly 40. In the event of thermal runaway, before opening the pressure relief mechanism 70, the breathable membrane assembly 40 can be destroyed at the first weak zone 212 to provide a certain degree of pressure relief. If the internal pressure of the battery cell 20 still increases, the pressure relief mechanism 70 can be opened again to relieve pressure.

[0121] According to some embodiments of the present application, when the valve body 31 of the one-way valve 30 is arranged on the outer surface 21a of the wall, and at least part of the valve body 31 protrudes from the outer surface 21a, that is, the one-way valve 30 is arranged on the side of the wall facing the outside of the shell, a variety of one-way valves 30 with different structures can be set.

[0122] Please refer to Figures 10, 11, 12, and 13. Figure 10 is a front view of a one-way valve according to one or more embodiments; Figure 11 is a schematic diagram of the exploded structure of a one-way valve according to one or more embodiments; Figure 12 is a schematic diagram of the cross-sectional structure of a one-way valve according to one or more embodiments; and Figure 13 is a schematic diagram of the partial cross-sectional structure of a battery cell according to one or more embodiments. In one embodiment, the valve body 31 includes a valve seat 311 and a valve cover 312. The valve cover 312 includes a cover top wall 3121 and a cover side wall 3122 connected to the cover top wall 3121. The cover top wall 3121, the cover side wall 3122, and the valve seat 311 enclose a valve cavity 313. The valve seat 311 is provided with an air inlet 313a, and the valve cover 312 is provided with an air outlet 313b. This facilitates the discharge of gas.

[0123] In this embodiment, the valve body 31 of the one-way valve 30 is provided with a valve seat 311 and a valve cover 312. The one-way valve 30 with this structure is provided with the valve body 31 as two parts, so that it is convenient to assemble the valve core 32 into the valve cavity 313, which is beneficial to reduce the difficulty of assembling the one-way valve 30.

[0124] According to some embodiments of the present application, the valve seat 311 has a first through hole 3111 penetrating the valve seat 311, and the air inlet 313a is the first through hole 3111, that is, the first through hole 3111 serves as the air inlet 313a of the valve cavity 313. This arrangement facilitates the outward transmission of gas inside the battery cell 20.

[0125] According to some embodiments of the present application, the cover sidewall 3122 has a second through hole 31221 penetrating the cover sidewall 3122, and the gas outlet 313b is the second through hole 31221, that is, the second through hole 31221 serves as the gas outlet 313b of the valve cavity 313. This arrangement facilitates the outward transmission of gas inside the battery cell 20.

[0126] According to some embodiments of the present application, the second through hole 31221 extends to an end of the cover side wall 3122 in a direction away from the cover top wall 3121 .

[0127] As shown in Figure 11, the direction away from the cover top wall 3121 is the direction from the cover top wall 3121 to the valve seat 311 (X direction in the figure), and the second through hole 31221 is formed by removing part of the structure of the cover side wall 3122. Along the X direction, the cover side wall 3122 is directly hollowed out to the bottom end of the cover side wall 3122.

[0128] In one embodiment, along the axial direction of the valve cavity 313 (the Y direction in the figure), the sealing interface between the valve core 32 and the valve seat 311 is higher than or flush with the bottom wall of the second through hole 31221. Furthermore, along the X direction, the lower opening surface of the second through hole 31221 can be flush with the sealing surface between the blocking member 321 and the valve seat 311, i.e., the sealing interface is higher than or flush with the bottom wall of the second through hole 31221. The so-called bottom wall of the second through hole 31221 refers to the lowest point of the second through hole 31221, as indicated by arrow P in Figure 11. Along the X direction, the lower opening surface of the second through hole 31221 is the bottom wall of the second through hole 31221. This arrangement allows for the timely discharge of electrolyte liquid carried along with the gas when the one-way valve 30 is opened for venting (i.e., when the blocking member 321 opens the sealing interface), preventing electrolyte from accumulating on the outer edge of the blocking member 321, thereby effectively ensuring the sealing and repeatable opening function of the one-way valve 30.

[0129] According to some embodiments of the present application, there are multiple second through holes 31221, and the multiple second through holes 31221 are spaced apart in the circumferential direction of the cover side wall 3122. This arrangement allows for faster exhaust of gas when the one-way valve 30 is opened for exhaust, shortening the exhaust time, that is, shortening the time that the battery cell 20 casing is in the open state, thereby reducing the intrusion of external moisture into the battery cell 20 system during the valve opening period.

[0130] Please refer to Figure 12. According to some embodiments of the present application, a first guide column 31211 is protruded from the side of the cover top wall 3121 facing the valve cavity 313, and a third through hole 31212 is provided on the cover top wall 3121, which passes through the cover top wall 3121 and the first guide column 31211, or a third through hole 31212 is provided on the cover top wall 3121, which passes through the cover top wall 3121, and the air outlet 313b is the third through hole 31212.

[0131] Specifically, a first guide post 31211 is protruding from the side of the cover top wall 3121 facing the valve cavity 313. A third through hole 31212 is formed on the cover top wall 3121, penetrating the cover top wall 3121 and the first guide post 31211. The gas outlet 313b is the third through hole 31212. In other words, the third through hole 31212 serves as the gas outlet 313b of the valve cavity 313. This arrangement facilitates the outward transmission of gas from within the battery cell 20.

[0132] Please continue to refer to Figures 10, 11, 12 and 13. According to some embodiments of the present application, the valve cover 312 also includes a flange wall 31222, the cover side wall 3122 connects the cover top wall 3121 and the flange wall 31222, the flange wall 31222 extends toward a side away from the valve cavity 313 relative to the cover side wall 3122, and the flange wall 31222 is connected to the valve seat 311.

[0133] According to some embodiments of the present application, the valve cover 312 is connected to the valve seat 311. Specifically, a first recessed groove 3112 is provided on the side of the valve seat 311 facing the valve cover 312, which is recessed relative to the surface of the valve seat 311. At least a portion of the flange wall 31222 is accommodated in the first recessed groove 3112 and connected to the valve seat 311.

[0134] In this embodiment, a first recess 3112 is provided on the side of the valve seat 311 facing the valve cover 312, and at least a portion of the flange wall 31222 is accommodated in the first recess 3112. The one-way valve 30 adopting such a structure can, on the one hand, save the space occupied by the valve body 31 in the thickness direction of the end cover 21, and on the other hand, improve the structural stability of the valve cover 312 assembled on the valve seat 311.

[0135] According to some embodiments of the present application, the flange wall 31222 is housed within the first recess 3112 and connected to the valve seat 311. The thickness of the flange wall 31222 is less than or equal to the depth of the first recess 3112, so that after the flange wall 31222 is connected to the valve seat 311, the surface of the flange wall 31222 facing the lid top wall 3121 is flush with the surface of the valve seat 311 facing the valve cover 312; or the surface of the flange wall 31222 facing the lid top wall 3121 is lower than the surface of the valve seat 311 facing the valve cover 312. As shown in Figures 12 and 13, after the valve cover 312 is connected to the valve seat 311, the flange wall 31222 is flush with the surface of the valve seat 311. This arrangement can reduce the overall installation height of the one-way valve 30.

[0136] According to some embodiments of the present application, the material of the valve seat 311 can be a metal material, such as copper, iron, aluminum, steel or aluminum alloy. Similarly, the material of the valve cover 312 can also be a metal material, such as copper, iron, aluminum, steel or aluminum alloy. The valve seat 311 and the valve cover 312 can be made of the same material or different materials. The valve cover 312 and the valve seat 311 can be assembled by welding (such as laser welding); they can also be assembled by mechanical interference, but the static friction generated by the interference must be greater than the rebound force of the elastic member 322.

[0137] According to some embodiments of the present application, the flange wall 31222 is welded to the valve seat 311; wherein, in the circumferential direction of the cover side wall 3122, at least a portion of the first weld mark W1 between the flange wall 31222 and the valve seat 311 is staggered with the second through hole 31221 on the cover side wall 3122.

[0138] The flange wall 31222 is an annular component having a certain thickness. The outer peripheral surface of the flange wall 31222 serves as a connecting surface 31222a and is welded to the wall surface of the first sink 3112. Furthermore, the connecting surface 31222a of the flange wall 31222 can be configured as an inclined surface, and the wall surface of the first sink 3112 can also be configured as an inclined surface, so that the connecting surface 31222a of the flange wall 31222 aligns with the wall surface of the first sink 3112. As shown in Figures 12 and 13, the flange wall 31222 and the first sink 3112 can form a structure that fits together. In this way, the welding quality can be improved, and the strength and stability of the connection can be enhanced. Furthermore, the valve cover 312 and the valve seat 311 are preferably made of the same material to achieve better welding quality.

[0139] According to some embodiments of the present application, at least a portion of the first weld mark W1 of the flange wall 31222 welded to the valve seat 311 is staggered with the second through hole 31221 along the circumference of the cover side wall 3122. As shown in FIG10 , welding can be performed at a location on the cover side wall 3122 where no second through hole 31221 is formed. There can be multiple first weld marks W1, distributed along the circumference of the cover side wall 3122, and the distribution of the first weld marks W1 can be staggered with the distribution of the second through holes 31221. In other words, multiple second through holes 31221 are spaced apart along the circumference of the cover side wall 3122, and the locations between adjacent second through holes 31221 where no holes are formed have a solid wall, so welding is performed at the location with the solid wall. The first weld mark W1 herein refers to the weld site or location between the flange wall 31222 and the valve seat 311 and does not necessarily indicate the presence of a weld mark in the actual product. The presence of a weld mark varies depending on the welding process and should not be construed as a requirement. In this way, the solid wall provides a certain degree of heat resistance, protecting the sealing member 321 of the valve core 32 and reducing the effects of high welding temperatures on the sealing member 321. This prevents heat deformation of the sealing member 321, which could lead to failure of the sealing interface when the valve is not open.

[0140] According to some embodiments of the present application, the valve core 32 may include an elastic member 322 and a sealing member 321, the elastic member 322 is arranged in the valve cavity 313, and the sealing member 321 is movably arranged in the valve cavity 313, and the sealing member 321 is used to block the air inlet under the action of the elastic member 322, and to open the air inlet under the action of the gas inside the shell.

[0141] Specifically, the elastic member 322 is arranged in the valve cavity 313, and the blocking member 321 is movably arranged in the valve cavity 313. The elastic member 322 is configured to provide elastic force to the blocking member 321, and the sealing and opening of the valve cavity 313 are achieved through the deformation of the elastic member 322.

[0142] Among them, the blocking member 321 is movably arranged in the valve cavity 313, that is, the blocking member 321 can move in the valve cavity 313, so that the blocking member 321 can block the air inlet 313a when it moves close to the air inlet 313a, and conversely, when the blocking member 321 moves away from the air inlet 313a, it can open the air inlet 313a.

[0143] In some embodiments, the blocking member 321 is loosely fitted with the inner wall of the valve cavity 313 .

[0144] Optionally, the elastic member 322 is an elastic component, and its structure can be various, such as a shrapnel, a spring or an elastic rubber. Exemplarily, the elastic member 322 is a spring. Using a spring as the elastic member disposed in the valve cavity, on the one hand, facilitates the assembly of the elastic member, which helps to reduce the difficulty of assembling the elastic member in the valve cavity, and on the other hand, enables the direction in which the elastic member applies the elastic force to the blocking member to be relatively stable. In some embodiments, the material of the elastic member includes steel, iron or aluminum. The elastic member made of steel, iron or aluminum has good toughness and can alleviate the phenomenon of elastic failure of the elastic member, which helps to increase the service life of the elastic member.

[0145] In some embodiments, the blocking member 321 is used to block the air inlet 313a under the action of the elastic member 322, and is used to open the air inlet 313a under the action of the gas inside the shell. That is, the elastic member 322 can provide elastic force for the blocking member 321, so that the blocking member 321 can abut against the bottom surface of the valve cavity 313 to block the air inlet 313a. Conversely, when the force of the gas inside the shell acting on the blocking member 321 is greater than the elastic force of the elastic member 322, the gas inside the shell can overcome the elastic force of the elastic member 322 and push the blocking member 321 to separate from the bottom surface of the valve cavity 313, so that the blocking member 321 can open the air inlet 313a, so that the gas inside the shell can enter the valve cavity 313 through the air inlet 313a and then be discharged through the air outlet 313b.

[0146] Furthermore, the blocking member 321 includes a pressing portion 3212 and a sealing portion 3211. Along the axial direction of the valve cavity 313, the two ends of the elastic member respectively abut against the valve cover and the pressing portion. The sealing portion is connected to the side of the pressing portion away from the valve cover. The sealing portion is used to block the air inlet channel.

[0147] Among them, the stiffness of the clamping part 3212 is greater than the stiffness of the sealing part 3211, the sealing part 3211 is connected to the side of the clamping part 3212 away from the top wall 3121 of the cover, the sealing part 3211 is used to seal the air inlet 313a, and the elastic part 322 is arranged between the top wall 3121 of the cover and the clamping part 3212. The clamping part 3212 can be pressed against the sealing part 3211 under the elastic force of the elastic part 322, so that the upper surface of the sealing part 3211 is effectively in contact with the clamping part 3212, so that the sealing part 3211 is against the bottom surface of the valve cavity 313, thereby sealing the air inlet 313a through the sealing part 3211.

[0148] According to some embodiments of the present application, the rigidity of the pressing portion 3212 is greater than the rigidity of the sealing portion 3211, and the provision of the pressing portion 3212 enables the force applied by the elastic member to be effectively transmitted to the sealing portion 3211. In other words, the rigidity of the pressing portion is greater than the rigidity of the sealing portion, that is, the deformation resistance of the pressing portion is greater than the deformation resistance of the sealing portion, so that the pressing portion can better press the sealing portion against the bottom surface of the installation cavity to seal the air inlet. Exemplarily, the material of the pressing portion can be a variety, such as steel, iron or aluminum. Similarly, the material of the sealing portion can also be a variety, such as rubber, silicone or plastic.

[0149] Optionally, the connection structure between the pressing portion and the sealing portion may be various, such as clamping, bolting, or bonding.

[0150] By setting the sealing member to include two parts, a pressing part and a sealing part, the pressing part is set on the side of the sealing part facing the valve cover, the sealing part is used to seal the air inlet, and the two ends of the elastic member are respectively against the valve cover and the pressing part, so that the elastic member can exert elastic force on the sealing part through the pressing part, which is beneficial to improve the balance of the elastic force of the elastic member acting on the sealing part, and thus can effectively improve the sealing effect of the sealing part on the air inlet.

[0151] According to some embodiments of the present application, the sealing portion 3211 is made of a material that is resistant to electrolyte, such as fluororubber, PFA, EPDM, etc. Different sealing materials have different physical properties, and accordingly, different forces are required to achieve sealing.

[0152] Please refer to Figure 14, which is a schematic diagram of a cross-sectional structure of a wall portion according to one or more embodiments. According to some embodiments of the present application, the one-way valve 30 is disposed on the wall portion, and the one-way valve 30 may be disposed on the end cover 21. The end cover 21 is provided with a first exhaust hole 291. The first exhaust hole 291 includes a through hole section 280 and a first hole section 281. The through hole section 280 and the first hole section 281 are arranged along the thickness direction of the end cover 21. The through hole section 280 connects the interior of the shell with the exterior of the shell. The first hole section 281 is located on the side of the through hole section 280 facing away from the interior of the shell. The aperture of the first hole section 281 is larger than the aperture of the through hole section 280. The one-way valve 30 is at least partially accommodated in the first hole section 281.

[0153] Among them, the first exhaust hole 291 is a countersunk hole recessed relative to the outer surface 21a of the end cover 21. When the one-way valve 30 is connected to the end cover 21, part of the structure of the one-way valve 30 can be embedded in the first exhaust hole 291 to reduce the installation height.

[0154] Please refer to Figure 13. According to some embodiments of the present application, a first step surface 311b and a second step surface 311c are provided on the side of the valve seat 311 facing the valve cover 312. The first step surface 311b is closer to the valve cover 312 than the second step surface 311c. The first sink 3112 is provided on the first step surface 311b.

[0155] The first hole section 281 includes a circumferential hole side surface, and the outer peripheral surface of the valve cover 312 / valve seat 311 of the one-way valve 30 is welded to the hole side surface. The outer peripheral surface of the second step surface 311c is welded to the hole side surface.

[0156] According to some embodiments of the present application, the side surface of the hole matches the outer circumference of the valve cover 312 / valve seat 311 of the one-way valve 30, and both the side surface of the hole and the outer circumference of the valve cover 312 / valve seat 311 of the one-way valve 30 are arranged at an acute angle to the central axis of the first exhaust hole 291. This arrangement can enhance the connection strength.

[0157] According to some embodiments of the present application, the one-way valve 30 is welded to the end cap 21. As shown in Figure 13, the valve seat 311 of the one-way valve 30 can be welded to the end cap 21; specifically, the valve cap 312 of the one-way valve 30 is connected to the valve seat 311, and the valve seat 311 is welded to the end cap 21. In other embodiments, the valve seat 311 of the one-way valve 30 can also be connected to the valve cap 312, and the valve cap 312 is welded to the end cap 21.

[0158] According to some embodiments of the present application, stress relief grooves are provided around the third weld mark between the valve cover 312 / valve seat 311 and the end cover 21. These stress relief grooves may be provided only on the end cover 21, only on the valve cover 312 / valve seat 311, or on both the end cover 21 and the valve cover 312 / valve seat 311. Optionally, a first stress relief groove is provided on the side of the valve seat 311 / valve cover 312 facing the exterior of the housing; and / or a second stress relief groove is provided on the side of the wall facing the exterior of the housing.

[0159] According to some embodiments of the present application, the exhaust assembly includes a breathable membrane assembly 40 , wherein the breathable membrane assembly 40 includes a breathable membrane 41 , and the breathable membrane 41 is configured to allow gas inside the battery cell to be discharged through the breathable membrane.

[0160] According to some embodiments of the present application, the breathable membrane assembly 40 includes a breathable membrane 41. The breathable membrane 41 is made of a breathable material with excellent air permeability, allowing gas molecules to pass through. By selecting the breathable membrane assembly 40 as the exhaust component, the battery cell can be sealed to discharge internal gas through the breathable membrane 41, and the gas inside the battery cell housing is promptly discharged outside the housing, thereby preventing the air pressure inside the battery cell housing from being too high, reducing the risk of premature opening of the pressure relief mechanism, and significantly improving the battery cell lifespan.

[0161] Furthermore, the breathable membrane 41 also has liquid-isolating properties, preventing liquid from passing through, and therefore, can prevent the overflow of the electrolyte while discharging gas. In addition, the breathable membrane 41 can also block external water vapor, dust and impurities from entering the interior of the battery cell, protect the internal environment of the battery cell, and effectively improve the reliability of the battery cell. The breathable membrane 41 also has good weather resistance, chemical corrosion resistance, and structural stability. If it is an automotive power battery, it also needs to have oleophobicity. Therefore, the material of the breathable membrane 41 can be selected from polymer materials, such as polytetrafluoroethylene, polypropylene, polyethylene, polyurethane, etc. In addition, since the generation of gas inside the battery cell will cause the internal pressure to rise rapidly, the breathable membrane needs to have certain mechanical strength and elasticity.

[0162] Please refer to Figure 15, which is a schematic cross-sectional view of a breathable membrane assembly according to one or more embodiments. According to some embodiments of the present application, the breathable membrane assembly 40 includes a breathable membrane 41 and a connector 42, which is used to support the breathable membrane 41. The connector 42 is provided with a first breathable hole 491, and the breathable membrane 41 is disposed on the connector 42. The breathable membrane 41 covers the first breathable hole 491. The breathable membrane is configured to allow gas inside the battery cell to pass through the breathable membrane and be discharged.

[0163] The connector 42 can support the breathable membrane 41 and reduce the risk of excessive deformation of the breathable membrane 41. At the same time, the connector 42 can also serve as a medium for connecting other components of the breathable membrane assembly 40. The breathable membrane 41 is connected to other components through the connector 42 to improve the stability of the connection. The connector 42 is provided with at least one first air hole 491 as a release channel for the gas inside the battery cell so that the gas can pass through the connector 42. The shape of the first air hole 491 includes geometric shapes such as circle, square, and ellipse. The connector 42 can also be provided with multiple first air holes 491. The aperture, shape, and arrangement of the first air holes 491 are not specifically limited here. Optionally, the aperture of the first air hole 491 can be less than or equal to the aperture of the exhaust hole on the battery cell.

[0164] In one embodiment, connector 42 may be a metal member, a resin member, or the like. The metal member may be made of copper, iron, aluminum, steel, or an aluminum alloy. Selecting a metal connector 42 facilitates welding of the connector 42 to the wall. The following description of this application utilizes a metal connector 42 as an example, but this is not intended to limit this embodiment and should not restrict this application. The present invention is also applicable to connectors made of non-metallic materials.

[0165] As shown in FIG15( a ), the breathable membrane 41 can be directly provided on the surface of the metal member 42 . In other embodiments, a sink can also be provided on the metal member 42 .

[0166] Referring to FIG. 15( b ), according to some embodiments of the present application, the metal member 42 has a first annular platform T1 that is recessed relative to the surface of the metal member 42 . The first annular platform T1 surrounds the first vent 491 , and the breathable membrane 41 is disposed on the first annular platform T1 . This arrangement can reduce the installation height of the breathable membrane assembly 40 .

[0167] Please refer to Figure 16, which is a schematic cross-sectional view of a breathable membrane assembly 40 according to one or more embodiments. According to some embodiments of the present application, the breathable membrane assembly 40 further includes a backing member 43, which is disposed between the breathable membrane 41 and the metal member 42. The backing member 43 has a higher air permeability than the breathable membrane 41.

[0168] The breathable membrane assembly 40 includes a breathable membrane 41, a metal part 42 and a backing part 43. The breathable membrane 41 is arranged on the metal part 42, and the backing part 43 is arranged between the breathable membrane 41 and the metal part 42. The backing part 43 is used to support the breathable membrane 41 and allow gas to pass through the breathable membrane 41.

[0169] Backing member 43 supports the breathable membrane 41, reducing the risk of deformation. Backing member 43 is made of a material with better air permeability than the breathable membrane 41 to ensure it does not interfere with the ventilation process of the breathable membrane 41. Backing member 43 is also corrosion-resistant and heat-resistant. The material options for backing member 43 are diverse, including porous polymers such as polypropylene, polyamide, polytetrafluoroethylene, and polyperfluoroethylene propylene. Porous metal organic frameworks, carbon membranes, and ceramics are also possible, but are not limited here.

[0170] As shown in Figure 16(a), the metal component 42 also has a second annular surface T2 that is recessed relative to the surface of the metal component 42. This second annular surface T2 surrounds the first air vent 491, and the backing member 43 is mounted on this second annular surface T2. The second annular surface T2 supports the backing member 43, while the breathable membrane 41 can be directly attached to the surface of the metal component 42. In this configuration, due to the relatively small thickness of the breathable membrane 41, the overall height of the breathable membrane assembly 40 is relatively minimal. By reducing the number of recessed surfaces on the metal component 42, the manufacturing process is simplified while also improving the strength of the metal component 42.

[0171] As shown in (b) of Figure 16, the metal part 42 has a first annular table T1 and a second annular table T2 that are recessed relative to the surface of the metal part 42, and a transition surface T3. The first annular table T1 is arranged around the second annular table T2, and the transition surface T3 connects the first annular table T1 and the second annular table T2. The first annular table T1 is closer to the surface of the metal part 42 than the second annular table T2. The second annular table T2 is arranged around the first air hole 491. The backing member 43 is arranged on the second annular table T2, and the breathable membrane 41 is arranged on the first annular table T1.

[0172] The first annular table surface T1 and the second annular table surface T2 are formed by inward depressions on the surface of the metal member 42. This can be achieved by stamping the metal member 42 to form the inward depressions, or by etching the metal member 42 to remove a portion of the structure. The depth of the depressions of the first annular table surface T1 and the second annular table surface T2 relative to the surface of the metal member 42 can be set based on the thickness of the breathable membrane 41 and the backing member 43. Preferably, the depth of the depression of the second annular table surface T2 relative to the first annular table surface T1 (i.e., the height of the transition surface T3) is equal to the thickness of the backing member 43, so that the second annular table can accommodate the backing member 43, and the surface of the backing member 43 facing the breathable membrane 41 is flush with the first annular table surface T1. Furthermore, the depression depth of the first annular platform T1 relative to the surface of the metal component 42 is equal to the thickness of the breathable membrane 41 , so that the first annular platform can accommodate the breathable membrane 41 , and the side surface of the breathable membrane 41 away from the metal component 42 is flush with the surface of the metal component 42 .

[0173] By providing a recessed platform on the metal member 42 , the surface of the breathable membrane 41 can be flush with the surface of the metal member 42 , thereby reducing the overall height of the breathable membrane assembly 40 and further reducing the installation height of the breathable membrane assembly 40 .

[0174] In one embodiment, the breathable membrane 41 and the metal part 42 are compositely connected, for example, the breathable membrane 41 and the metal part 42 can be connected by using a nano injection molding process. Nano injection molding refers to nano molding technology (NMT, i.e., Nano Molding Technology), which is a process of combining metal and plastic using nanotechnology. That is, the metal surface is first nano-treated, and then the plastic is directly injection-molded on the metal surface, so that the metal and plastic can be integrally formed and finally combined into a product. The "nano" referred to here refers to a microporation process, that is, the metal surface is subjected to nano-level microporation treatment through a specific solution. The main purpose is to better combine the metal surface with the plastic and improve the connection strength.

[0175] According to some embodiments of the present application, the breathable membrane assembly 40 is disposed on a wall portion, which has a first recessed portion S1 that is recessed relative to the wall portion. The first recessed portion S1 is disposed around the second exhaust hole 292, and the breathable membrane assembly 40 is at least partially located on the first recessed portion S1. Alternatively, the breathable membrane assembly 40 may be disposed on the end cap 21.

[0176] Please refer to Figures 17 and 18. Figure 17 is a schematic diagram of a partial cross-sectional structure of a battery cell 20 according to one or more embodiments, and Figure 18 is a schematic diagram of a partial cross-sectional structure of a battery cell 20 according to one or more embodiments. According to some embodiments of the present application, the end cap 21 has a first recessed portion S1 that is recessed relative to the surface of the end cap 21. The first recessed portion S1 is disposed around the second vent 292, and at least a portion of the breathable membrane assembly 40 is disposed on the first recessed portion S1.

[0177] The end cap 21 includes an outer surface 21a and an inner surface 21b disposed opposite each other, with the outer surface 21a facing the exterior of the housing and the inner surface 21b facing the interior of the housing. The breathable membrane assembly 40 can be disposed on the side of the end cap 21 facing the interior of the housing or on the side of the end cap 21 facing the exterior of the housing.

[0178] As shown in Figures 17(a) and (b), the breathable membrane assembly 40 is disposed on the side of the end cap 21 facing the interior of the housing. The end cap 21 has an outer surface 21a and an inner surface 21b disposed opposite each other, with the outer surface 21a facing the exterior of the housing and the inner surface 21b facing the interior of the housing. The end cap 21 has a first recessed portion S1 that is recessed relative to the inner surface 21b of the end cap 21.

[0179] Specifically, the first sinking platform S1 is recessed relative to the inner surface 21b of the end cover 21, and the breathable membrane assembly 40 is disposed on the first sinking platform S1. Optionally, the breathable membrane assembly 40 can be connected to the end cover 21 via a metal member 42.

[0180] Among them, the first depression S1 is formed by the inner surface 21b of the end cover 21 being recessed in the direction of the outer surface 21a of the end cover 21. The end cover 21 can be stamped to form the recessed first depression S1, or the end cover 21 can be etched to remove part of the structure to form the recessed first depression S1. The recessed depth of the first depression S1 relative to the inner surface 21b of the end cover 21 can be set according to the thickness of the breathable membrane assembly 40. The thickness of the breathable membrane assembly 40 is the overall thickness including the breathable membrane 41, the metal part 42 and the backing part 43. As mentioned above, the breathable membrane 41 and the backing part 43 can be accommodated in the annular platform on the metal part 42 that is recessed relative to the surface of the metal part 42, that is, the overall thickness of the breathable membrane assembly 40 can be equal to the thickness of the metal part 42. Preferably, the depth of the first recessed portion S1 relative to the inner surface 21b of the end cap 21 is equal to the thickness of the breathable membrane assembly 40, so that the breathable membrane assembly 40 is accommodated within the first recessed portion S1, and the surface of the breathable membrane assembly 40 facing the interior of the housing is flush with the inner surface 21b of the end cap 21. In this way, the installation height of the breathable membrane assembly 40 can be reduced, thereby reducing the space occupied by the battery cell 20 interior housing and improving the space utilization inside the housing.

[0181] As shown in Figure 17(a), the breathable membrane 41 can be positioned on the side of the metal component 42 facing the interior of the housing; this arrangement reduces the impact of the operating environment of the battery cell 20 on the breathable membrane 41. As shown in Figure 17(b), the breathable membrane 41 can also be positioned on the side of the metal component 42 facing the end cap 21, that is, between the metal component 42 and the end cap 21; this arrangement facilitates assembly of the breathable membrane assembly 40.

[0182] As shown in Figure 18, the breathable membrane assembly 40 is disposed on the side of the end cap 21 facing the exterior of the housing. Specifically, a first recessed portion S1 is recessed relative to the outer surface 21a of the end cap 21. The breathable membrane assembly 40 is disposed on this first recessed portion S1 and connected to the end cap 21 via a metal member 42. In this embodiment, the first recessed portion S1 is formed by recessing the outer surface 21a of the end cap 21 toward the inner surface 21b of the end cap 21. Similarly, the depth of the recessed portion S1 relative to the outer surface 21a of the end cap 21 can be equal to the thickness of the breathable membrane assembly 40.

[0183] As shown in Figure 18 , the breathable membrane 41 is disposed on the side of the metal member 42 facing the interior of the housing, that is, between the end cap 21 and the metal member 42. This arrangement reduces the impact of the operating environment of the battery cell 20 on the breathable membrane 41. In other embodiments, the breathable membrane 41 can also be disposed on the side of the metal member 42 facing the exterior of the housing.

[0184] According to some embodiments of the present application, the connecting member is welded to the wall portion; optionally, a stress relief groove is provided around the fourth weld mark between the connecting member and the wall portion; optionally, a third stress relief groove is provided on the connecting member around the fourth weld mark between the connecting member and the wall portion; and / or a second stress relief groove is provided on the wall portion around the fourth weld mark between the connecting member and the wall portion.

[0185] Please refer to Figure 19, which is a schematic diagram of the exploded structure of a battery cell according to one or more embodiments. According to some embodiments of the present application, the battery cell 20 further includes a protective patch 60, which is disposed on the side of the end cap 21 facing the exterior of the housing. Specifically, the protective patch 60 is disposed on the outer surface 21a of the end cap 21 to provide a certain degree of protection for the end cap 21. The protective patch 60 can be made of a variety of materials, such as rubber, silicone, or plastic.

[0186] According to some embodiments of the present application, a first avoidance hole 601 penetrating the protective patch 60 is provided on the protective patch 60 , and the first avoidance hole 601 is used for the one-way valve 30 in the exhaust assembly to pass through.

[0187] According to some embodiments of the present application, in an embodiment in which an electrode terminal 25 is provided on the end cap 21, as shown in FIG19 , the protective patch 60 is provided with a second avoidance hole 602 at the position corresponding to the electrode terminal 25. The second avoidance hole 602 runs through both sides of the protective patch 60. The second avoidance hole 602 is used to allow the electrode terminal 25 to pass through, avoiding the electrode terminal 25. Exemplarily, two electrode terminals 25 are provided on the end cap 21, and correspondingly, the protective patch 60 is provided with two second avoidance holes 602, each of which is used to allow one electrode terminal 25 to pass through.

[0188] According to some embodiments of the present application, an information collection hole 603 is provided on the protective patch 60 and penetrates the protective patch 60. The information collection hole 603 serves as a part of the exposed end cover 21, so as to facilitate setting an information code on the end cover 21 or connecting a detection element for sampling, etc.

[0189] In some embodiments, the permeability rate of the breathable membrane 41 is 3-10 mL / day. It can be 3-4 mL / day, 5-8 mL / day, or 9-10 mL / day. By setting the exhaust rate of the breathable membrane 41 to 3-10 mL / day, the phenomenon that the pressure relief mechanism 70 cannot be actuated due to excessive exhaust when the battery cell 20 experiences thermal runaway can be alleviated, so that the pressure relief mechanism 70 can be actuated and stably discharge the internal pressure of the battery cell 20 when the battery cell 20 experiences thermal runaway, thereby helping to reduce the risk of fire and explosion of the battery cell 20 during thermal runaway. At the same time, the airtightness of the system is also taken into consideration to prevent the exhaust rate from being too fast, resulting in a deterioration in the airtightness, so as to maintain the airtightness of the battery system while discharging the gas.

[0190] The test method for the exhaust rate of the breathable membrane 41 may be carried out in accordance with GB / T1038-2000.

[0191] According to some embodiments of the present application, the opening pressure of the one-way valve is greater than or equal to 0.2 MPa; alternatively, greater than or equal to 0.4 MPa; and further alternatively, greater than or equal to 0.8 MPa. For example, the opening pressure of the valve core can be 0.20 MPa, 0.25 MPa, 0.30 MPa, 0.35 MPa, 0.40 MPa, 0.45 MPa, 0.50 MPa, 0.55 MPa, 0.60 MPa, 0.65 MPa, 0.70 MPa, 0.75 MPa, 0.80 MPa, 0.90 MPa, or 1.00 MPa.

[0192] The one-way valve opening pressure test method and principle can be tested based on the helium leakage standard. The helium leakage standard is defined as follows: if the leakage rate is less than 10^-6Pa.m^3 / s, the system is considered to be sealed; if the leakage rate is greater than 10^-6Pa.m^3 / s, it indicates that there is a gas leak in the system.

[0193] During testing, the test chamber is sealed with a one-way valve and filled with helium. The amount of helium in the test chamber environment is monitored using a helium detector. If helium is detected and the leakage rate is greater than 10^-6Pa.m^3 / s, it means that the test chamber is no longer sealed and helium is leaking out. The helium leakage rate is continuously monitored. When the leakage rate is greater than 10^-5Pa.m^3 / s, the one-way valve is determined to be open for release. The pressure in the test chamber at this time is recorded as the opening pressure of the one-way valve.

[0194] In some embodiments, the battery cell 20 is an alkali metal battery, such as a sodium metal battery, a lithium metal battery, or a magnesium metal battery. Alkali metal batteries, when used in conjunction with exhaust components, can promptly exhaust gases generated during normal operation of the alkali metal battery, thereby extending the service life of the alkali metal battery.

[0195] The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets containing active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute the tabs. The positive and negative electrode tabs can be located together at one end of the main body or at both ends of the main body. During the charge and discharge process of the battery, the positive and negative electrode active materials react with the electrolyte, and the tabs connect to the electrode terminals to form a current circuit.

[0196] In one embodiment, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer disposed on at least one side of the positive electrode current collector, wherein the positive electrode active layer includes a positive electrode active material.

[0197] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active layer may be provided on either or both of the two facing surfaces of the positive electrode current collector.

[0198] In one embodiment, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0199] In one embodiment, the positive electrode material includes one or more of a polyanion positive electrode material, a phosphate positive electrode material, a sulfate positive electrode material, a silicate positive electrode material, and a borate positive electrode material. For example, in the positive electrode active material of a sodium battery, the polyanion compound includes a compound based on phosphoric acid and fluorophosphate. The compound based on phosphoric acid includes Na x1 Fe y1 P m1 O n1 For example, sodium iron phosphate with a higher capacity and sodium iron pyrophosphate with a higher voltage platform. Polyanionic compounds include sodium vanadium trifluorophosphate Na3V2(PO4)2F3, sodium vanadium fluorophosphate NaVPO4F, sodium vanadium phosphate Na3V2(PO4)3, Na4Fe3(PO4)2P2O7, NaFePO4, Na3V2(PO4)3. Prussian blue compounds are Na x MM(CN)6, where M and M are one or more of Fe, Mn, Co, Ni, Cu, Zn, Cr, Ti, V, Zr, and Ce, and 0 < x ≤ 2. The positive electrode active material in the lithium metal battery may include at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, or lithium iron manganese phosphate.

[0200] In one embodiment, the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active layer includes a negative electrode active material. In this embodiment, the battery cell is an ion battery. During the charge and discharge process of the battery, active ions (such as Li + 、Na + ) is embedded / deintercalated in the negative electrode active material.

[0201] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active layer may be disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0202] In one embodiment, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be obtained by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0203] In one embodiment, the negative electrode active material may include one or more of a silicon-based material, a silicon-carbon material, a carbon material, and a selenium-based material. Specifically, it includes one or more of artificial graphite, natural graphite, hard carbon, soft carbon, a silicon-based material, and a selenium-based material. The silicon-based material may be selected from one or more of elemental silicon, a silicon oxide (e.g., silicon 2 oxide), a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The selenium-based material may be selected from one or more of elemental selenium, a selenium oxide, and a selenium alloy.

[0204] In one embodiment, the negative electrode plate includes a negative electrode current collector and a carbonaceous coating provided on at least one surface of the negative electrode current collector. In this embodiment, the battery cell is a metal battery, and during the charge and discharge process of the battery, active ions are deposited / stripped at the negative electrode plate. The metal battery can be an alkali metal battery, such as a lithium metal battery, a sodium metal battery, a potassium metal battery, a zinc metal battery, or an aluminum metal battery. This type of battery can also be called a "negative electrode-free battery". During the charging process, the active ions (such as Na + ) is deposited onto the negative electrode current collector to form sodium metal. The provision of a carbon-containing coating facilitates more uniform metal deposition. The carbon-containing material includes one or more of conductive carbon, graphite, hard carbon, and carbon nanotubes.

[0205] In other embodiments, a conductive film layer may be deposited on the negative electrode current collector. Examples include alloy materials, titanium-based materials, active metals (e.g., sodium metal), carbon-based materials deposited with metals, composite materials containing metals, and alloy materials containing metals. Such alloy materials include, but are not limited to, sodium-tin alloys, sodium-germanium alloys, and sodium-antimony alloys. Such titanium-based materials include, but are not limited to, titanium dioxide, titanates, and titanium phosphates.

[0206] In one embodiment, the positive electrode active layer and the negative electrode active layer may further include a binder and a conductive agent. As an example, the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and at least one of a fluorine-containing acrylate resin. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0207] In one embodiment, the isolation membrane can be any known porous structure isolation membrane with good chemical stability and mechanical stability.

[0208] In one embodiment, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0209] The electrolyte conducts ions between the positive and negative electrodes. The electrolyte can be liquid, gel, or solid.

[0210] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent. The electrolyte salt dissolves to form electrolyte ions, and conduction is achieved through the movement of the electrolyte ions in the electrolyte salt.

[0211] In one embodiment, in a sodium battery, the electrolyte salt includes sodium hexafluorophosphate (NaPF6), sodium bis(fluorosulfonyl)imide (NaFSI), sodium trifluoromethanesulfonate (CF3NaO3S), sodium sulfide (Na2S), and the like. A lithium battery includes at least one lithium salt selected from the group consisting of lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium tetrafluoroborate, and lithium trifluoromethanesulfonate.

[0212] In one embodiment, the solvent includes one or more solvents selected from the group consisting of chain ethers, ethylene glycol dimethyl ether and its derivatives, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and cyclic ethers, specifically including dimethyl ether (DME), diethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, 2,2,2,2-trifluoroethyl ether, ethylene glycol diethyl ether, triethylene glycol dimethyl ether, ethylene glycol dimethyl ether derivatives, trifluoroethyl methyl carbonate (FEMC), dioxolane (DOL), acetonitrile (AN), fluorobenzene, triethyl phosphate (TEP), sulfolane, 2-methyltetrahydrofuran, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylacetamide, and the like.

[0213] In one embodiment, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives capable of improving certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0214] According to some embodiments of the present application, a battery 100 is provided, comprising a battery cell 20 according to any of the above-described embodiments. Referring to FIG. 20 , FIG. 20 is a schematic diagram of an exploded structure of a battery according to one or more embodiments. The battery 100 comprises a housing 10 and a battery cell 20, with the battery cell 20 contained within the housing 10. The housing 10 is configured to provide a storage space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap with each other and together define a storage space for the battery cell 20. The second portion 12 can be a hollow structure with one end open, and the first portion 11 can be a plate-like structure, overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 together define a storage space. Alternatively, the first portion 11 and the second portion 12 can each be a hollow structure with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the box body 10 formed by the first part 11 and the second part 12 can be in various shapes, such as a cylinder, a cuboid, etc.

[0215] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0216] Each battery cell 20 may be a secondary battery or a primary battery; specific examples include all types of primary or secondary batteries. For example, it may be a lithium battery, a sodium battery, a potassium battery, or other different types of secondary batteries. Lithium secondary batteries may include lithium metal secondary batteries, lithium ion secondary batteries, lithium polymer secondary batteries, or lithium ion polymer secondary batteries. Other types may include, but are not limited to, lithium sulfur batteries, sodium ion batteries, or magnesium ion batteries. Battery cells 20 may be cylindrical, flat, rectangular, or other shapes.

[0217] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0218] According to some embodiments of the present application, the present application further provides an electric device, which includes a battery cell according to any of the above solutions, and the battery cell is used to provide power to the electric device. The electric device can be any of the above devices or systems using the battery cell.

[0219] In some embodiments, the purposes of the electric equipment of the present application are not particularly limited, and it can be used for any electronic device known in the prior art. The battery disclosed in the embodiment of the present application can be used for electric equipment using a battery as a power source or various energy storage systems using a battery as an energy storage element. That is, a kind of electric equipment is provided. In some embodiments, the electric equipment of the present application can be used for, but not limited to, a laptop computer, a pen-input type computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a ship, a spacecraft, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large-scale battery for household use and a lithium-ion capacitor etc.

[0220] Electrical equipment can choose battery cells, battery modules or battery packs according to its usage requirements.

[0221] Please refer to Figure 21, which is a schematic structural diagram of a vehicle according to one or more embodiments. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0222] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0223] In the above embodiments, the provision of a breathable membrane assembly enables the battery cell to discharge internal gas through the breathable membrane while in a sealed state, promptly discharging the gas inside the battery casing to the outside of the casing. This prevents excessive pressure inside the battery casing, reduces the risk of premature valve opening of the pressure relief mechanism, and significantly improves the lifespan of the battery cell. One or more breathable membrane assemblies can be provided on a single battery cell, and the placement and manner of each breathable membrane assembly can vary. For example, one breathable membrane assembly can be provided on the side of the end cap facing the interior of the battery casing, and another breathable membrane assembly can be provided on the side of the end cap facing the exterior of the battery casing. Alternatively, one breathable membrane assembly can be provided on the end cap, and another breathable membrane assembly can be provided on the casing.

[0224] The above is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A battery cell, wherein: include: a housing having a wall portion; An exhaust assembly, disposed on the wall portion, the exhaust assembly comprising a one-way valve and / or a breathable membrane assembly, the breathable membrane assembly comprising a breathable membrane, and the exhaust assembly is used to exhaust the gas inside the housing; The wall portion is provided with a first weak strength area, and the first weak strength area is arranged along the circumference of the exhaust component.

2. The battery cell according to claim 1, wherein: The first strength weakened area includes a first thickness weakened area.

3. The battery cell according to claim 1 or 2, wherein: The first weak strength area includes a first groove recessed relative to the surface of the wall portion, and the first groove is arranged around the exhaust component.

4. The battery cell according to claim 3, wherein: The wall portion has an outer surface and an inner surface that are arranged opposite to each other, the outer surface is arranged toward the outside of the shell, and the inner surface is arranged toward the inside of the shell; The first groove is recessed relative to the outer surface; and / or The first groove is recessed relative to the inner surface.

5. The battery cell according to claim 1 or 2, wherein: The first weak strength area includes a plurality of second grooves recessed relative to the surface of the wall portion, and the plurality of second grooves are arranged at intervals in the circumferential direction of the exhaust component.

6. The battery cell according to claim 3, 4 or 5, wherein: The first weak strength area further includes a notch arranged at the bottom of the first groove and / or the second groove.

7. The battery cell according to any one of claims 1 to 6, wherein: The wall portion includes a wall body and a sinking portion, the wall body has an outer surface and an inner surface arranged opposite to each other, the outer surface is arranged toward the outside of the shell, and the inner surface is arranged toward the inside of the shell; the sinking portion is connected to the wall body, the sinking portion protrudes from the inner surface, and the first strength weak area is arranged on the sinking portion.

8. The battery cell according to any one of claims 1 to 7, wherein: The wall portion is provided with a first exhaust hole, the first exhaust hole communicates the inside of the shell with the outside of the shell, and the exhaust component includes a one-way valve, and the one-way valve covers the first exhaust hole.

9. The battery cell according to claim 8, wherein: The wall portion has an outer surface and an inner surface arranged opposite to each other, the outer surface is arranged toward the outside of the shell, and the inner surface is arranged toward the inside of the shell; the one-way valve is arranged on the outer surface, and the one-way valve includes a valve body, at least part of which protrudes from the outer surface.

10. The battery cell according to claim 9, wherein: The valve body is provided with a second weak strength area, the actuation pressure of the second weak strength area is greater than the valve opening pressure of the one-way valve, and the actuation pressure of the second weak strength area is less than the actuation pressure of the first weak strength area.

11. The battery cell according to claim 10, wherein: The valve body has a valve cavity inside, the valve body includes a valve seat and a valve cover, the valve cover includes a cover top wall and a cover side wall connected to the cover top wall, the cover top wall, the cover side wall and the valve seat enclose the valve cavity, and the second strength weak area is arranged on the cover side wall.

12. The battery cell according to claim 10 or 11, wherein: The second weak strength area includes a plurality of third grooves arranged on the side wall of the cover.

13. The battery cell according to claim 8, wherein: The one-way valve includes a valve body and a valve core, the valve body has a valve cavity inside, the valve body is provided with an air inlet and an air outlet, the air inlet is used to connect the valve cavity with the inside of the shell, and the air outlet is used to connect the valve cavity with the outside of the shell; the valve core is arranged in the valve cavity, the valve core is used to block the air inlet, and the valve core is configured to open the air inlet under the action of the gas inside the shell and release the gas inside the battery cell.

14. The battery cell according to claim 13, wherein: The valve body comprises: Valve seat; The valve cover comprises a cover top wall and a cover side wall connected to the cover top wall, the cover top wall, the cover side wall and the valve seat enclose the valve cavity, the valve seat is provided with the air inlet, the valve cover is provided with the air outlet, the valve seat has a first through hole penetrating the valve seat, and the air inlet is the first through hole.

15. The battery cell according to claim 13 or 14, wherein: The cover side wall has a second through hole penetrating the cover side wall, and the air outlet is the second through hole.

16. The battery cell according to claim 15, wherein: The second through hole extends to the end of the cover side wall in a direction away from the cover top wall; Optionally, there are a plurality of the second through holes, and the plurality of the second through holes are spaced apart and distributed in the circumferential direction of the cover side wall.

17. The battery cell according to any one of claims 14 to 16, wherein: The valve cover also includes a flange wall, the cover side wall connects the cover top wall and the flange wall, the flange wall extends toward a side away from the valve cavity relative to the cover side wall, and the flange wall is connected to the valve seat.

18. The battery cell according to claim 17, wherein: A first recessed groove that is recessed relative to the surface of the valve seat is disposed on a side of the valve seat that faces the valve cover, and at least a portion of the flange wall is accommodated in the first recessed groove and connected to the valve seat.

19. The battery cell according to claim 17 or 18, wherein: The flange wall is welded to the valve seat; wherein, in the circumferential direction of the cover side wall, at least a portion of a first weld mark between the flange wall and the valve seat is staggered with a second through hole on the cover side wall.

20. The battery cell according to any one of claims 13 to 19, wherein: The valve core comprises: An elastic member, disposed in the valve cavity; A blocking member is movably disposed in the valve cavity, and is used to block the air inlet under the action of the elastic member, and is used to open the air inlet under the action of the gas inside the shell.

21. The battery cell according to claim 20, wherein: The sealing member includes a pressing portion and a sealing portion. Along the axial direction of the valve cavity, the two ends of the elastic member respectively abut against the valve cover and the pressing portion. The sealing portion is connected to a side of the pressing portion away from the valve cover, and the sealing portion is used to seal the air inlet.

22. The battery cell according to any one of claims 8 to 21, wherein: The first exhaust hole includes a through hole segment and a first hole segment, the through hole segment and the first hole segment are arranged along the thickness direction of the wall portion, the first hole segment is located on the side of the through hole segment away from the interior of the shell, the aperture of the first hole segment is larger than the aperture of the through hole segment, and the one-way valve is at least partially accommodated in the first hole segment.

23. The battery cell according to claim 22, wherein: The first hole section includes a circumferentially arranged hole side surface, and the valve seat is provided with a first step surface and a second step surface on the side facing the valve cover. The first step surface is closer to the valve cover than the second step surface, and the outer circumferential surface of the second step is welded to the hole side surface.

24. The battery cell according to any one of claims 1 to 7, wherein: The wall portion includes a pressure relief mechanism and a pressure relief hole, the pressure relief hole connects the inside of the shell and the outside of the shell, the pressure relief mechanism includes a pressure relief sheet, the pressure relief sheet covers the pressure relief hole, the first strength weak area is arranged on the pressure relief sheet, the pressure relief mechanism is configured to actuate and release the internal pressure of the battery cell when the battery cell thermally runs away, and the actuation pressure of the pressure relief mechanism is greater than the actuation pressure of the first strength weak area.

25. The battery cell according to claim 24, wherein: A second exhaust hole is provided on the pressure relief sheet, and the second exhaust hole connects the interior of the shell with the exhaust assembly. The exhaust assembly includes a one-way valve or a breathable membrane assembly, and the one-way valve or the breathable membrane assembly is provided on the pressure relief sheet and covers the second exhaust hole.

26. The battery cell according to any one of claims 1 to 23, wherein: The wall portion is provided with a first exhaust hole, the first exhaust hole communicates the inside of the shell with the outside of the shell, and the exhaust assembly includes a breathable membrane assembly, and the breathable membrane assembly covers the first exhaust hole.

27. The battery cell according to claim 26, wherein: The breathable membrane assembly includes a breathable membrane and a connector, the breathable membrane is configured to allow gas inside the battery cell to pass through the breathable membrane and be discharged, the connector is provided with a first breathable hole, and the breathable membrane is provided on the connector and covers the first breathable hole.

28. The battery cell according to claim 27, wherein: The connecting member has a first annular table surface which is recessed relative to the surface of the connecting member. The first annular table surface is arranged around the first air permeable hole, and the air permeable membrane is arranged on the first annular table surface.

29. The battery cell according to claim 27 or 28, wherein: The breathable membrane assembly further comprises a backing member, which is arranged between the breathable membrane and the connecting member, and the air permeability rate of the backing member is greater than the air permeability rate of the breathable membrane.

30. The battery cell according to claim 29, wherein: The connecting member has a second annular table surface which is recessed relative to the surface of the connecting member, the second annular table surface is arranged around the first air vent, and the backing member is arranged on the second annular table surface.

31. The battery cell according to any one of claims 27 to 30, wherein: The connecting piece is a metal piece.

32. The battery cell according to any one of claims 27 to 31, wherein: The breathable membrane is arranged on a side of the connecting member facing the inside of the shell, and the breathable membrane covers the first breathable hole.

33. The battery cell according to any one of claims 26 to 32, wherein: The wall portion has a first sunken platform that is recessed relative to the surface of the wall portion. The first sunken platform is arranged around the first exhaust hole, and the breathable membrane assembly is at least partially located on the first sunken platform.

34. The battery cell according to any one of claims 1 to 33, wherein: The housing comprises: A housing having an opening formed therein, wherein the housing is used to accommodate the electrode assembly; an end cap for closing the opening; Wherein, the end cover is the wall portion; or The housing includes the wall portion; or The wall portion is a wall located at the top of the housing when the battery cell is in a placed state.

35. A battery, wherein: Comprising a battery cell as described in any one of claims 1-34.

36. An electrical device, wherein: The invention comprises a battery cell as claimed in any one of claims 1 to 34, wherein the battery cell is used to provide electrical energy.

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