Battery cell, battery device, energy storage device, energy storage system and charging network

Abstract

The utility model relates to the technical field of batteries, and discloses a battery monomer, a battery device, an energy storage device, an energy storage system and a charging network. Wherein a first accommodating space is defined by a shell of the battery monomer, and a first opening is formed in the shell; the electrode assembly is accommodated in the first accommodating space; the end cover covers the first opening and is provided with a pressure relief mechanism, the foaming device is arranged on the side, close to the electrode assembly, of the end cover in the first direction, the foaming device comprises a foaming layer and an overflow part, the foaming layer is configured to expand under the condition that a first preset parameter is exceeded, and the overflow part allows the foaming layer to overflow. Through the application, the solid particulate matters can be filtered during pressure relief of the battery monomer, so that the solid particulate matters sprayed out during pressure relief of the battery monomer are reduced to a certain extent, and the adverse risks of secondary combustion, insulation failure and environmental pollution of the sprayed solid particulate matters in the external environment of the battery monomer are reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to battery cells, battery devices, energy storage devices, energy storage systems, and charging networks. Background Art

[0002] New energy batteries are being used more and more widely in life and industry. For example, new energy vehicles equipped with batteries have been widely used. In addition, batteries are also being increasingly used in energy storage fields.

[0003] In the energy storage field, batteries can be installed in energy storage boxes or directly at the user's side. In these application scenarios, thermal runaway of a battery cell can release pressure through a pressure relief mechanism. This release of pressure can result in the ejection of solid particles, which are typically hot and conductive, potentially causing secondary combustion and insulation failure. Therefore, reducing the amount of solid particles ejected during pressure release is a research and development topic in the industry. Utility Model Content

[0004] To solve the above technical problems, the present application provides a battery cell, a battery device, an energy storage device, an energy storage system and a charging network.

[0005] This application is implemented through the following technical solutions.

[0006] A first aspect of an embodiment of the present application provides a battery cell, comprising a housing, wherein the housing defines a first accommodation space and is formed with a first opening;

[0007] an electrode assembly, the electrode assembly being accommodated in the first accommodation space;

[0008] An end cover, the end cover covers the first opening, and the end cover is provided with a pressure relief mechanism,

[0009] A foaming device is provided on a side of the end cover close to the electrode assembly along the first direction, and the foaming device includes a foaming layer and an overflow portion.

[0010] The foaming layer is configured to expand when exceeding a first predetermined parameter, and the overflow portion is for the foaming layer to overflow.

[0011] Therefore, the foaming layer expands after exceeding the first predetermined parameter, and directly covers the pressure relief mechanism through the foaming layer, filtering and blocking the combustible particles ejected from the battery cell during thermal runaway, thereby reducing the solid particles ejected from the battery cell during pressure relief to a certain extent, reducing the adverse risks of secondary combustion, insulation failure, and environmental pollution of the ejected solid particles in the external environment of the battery cell, and preventing the spread of thermal runaway.

[0012] In some embodiments, the foaming device includes a protective shell, the overflow portion is provided in the protective shell, the protective shell defines a second accommodating space, and the second accommodating space accommodates the foaming layer.

[0013] Thus, the protective shell can accommodate the foam layer, so that under normal conditions the foam layer will not interfere with the first accommodation space where the electrode assembly is located, thereby preventing it from affecting the normal cycle use of the battery cell.

[0014] The overflow portion includes a second opening and a temperature trigger layer. The second opening is formed on at least one side of the protective shell along the first direction. The temperature trigger layer closes the second opening. The temperature trigger layer is configured to connect the first storage space and the second storage space after exceeding a second predetermined parameter.

[0015] Thus, the temperature-triggered layer can include a temperature-sensitive material. By actively rupturing the temperature-sensitive trigger layer under a second predetermined parameter, the foaming layer can be facilitated to quickly fill the second accommodation space in the event of thermal runaway, filtering solid particles and reducing the number of solid particles that reach the pressure relief mechanism through the pressure relief channel and are ejected. Furthermore, the foaming device is controlled to prevent activation during normal cycling, thereby affecting the normal operation of the battery cells.

[0016] In some embodiments, when projected along the first direction onto a projection plane perpendicular to the first direction, the projection of the foaming device does not overlap with the projection of the pressure relief mechanism.

[0017] This improves the flexibility of the foaming device's placement and effectively utilizes the space inside the end cap. Furthermore, the foaming layer can fill the gap in the first accommodating space or partially cover the pressure relief mechanism, further reducing the number of solid particles that reach the pressure relief mechanism and are ejected from the pressure relief channel, thereby minimizing the impact on the pressure relief capacity of the battery cell.

[0018] In some embodiments, the battery cell includes an electrode terminal, which is arranged on the end cover, and the electrode terminal protrudes from the end cover on the side close to the electrode assembly along the first direction, and an insulating member is provided on the side of the pressure relief mechanism close to the electrode assembly along the first direction; along the second direction, the foaming device is arranged between the insulating member and the electrode terminal, and the second direction is perpendicular to the first direction.

[0019] In this way, the space between the insulating member and the electrode terminal can be fully utilized without occupying additional internal space of the battery, thereby improving the utilization rate of the internal space of the shell and reducing the impact on the capacity of the battery cell.

[0020] In some embodiments, the electrode assembly includes a tab and a main body, and the foaming device is located between the tab and the end cover along the first direction.

[0021] As a result, the foaming device is located close to the pressure relief mechanism, and the foaming layer can more effectively fill the pressure relief channel, thereby improving the filtering and blocking effects on solid particles.

[0022] In some embodiments, when projected along the first direction onto a projection plane perpendicular to the first direction, at least part of the projection of the foaming device overlaps with the projection of the pressure relief mechanism; the protective shell has the second opening on both sides along the first direction, and the temperature triggering layer closes each of the second openings.

[0023] Since the projection of the foaming device partially overlaps with the projection of the pressure relief mechanism, it is beneficial for the foaming layer to directly cover the pressure relief mechanism area, forming a continuous foaming layer at the pressure relief mechanism to prevent solid particles from escaping. The gas can be discharged from the pressure relief mechanism through the area where the projections do not overlap and the second opening position, reducing the impact on the pressure relief capacity of the battery cell.

[0024] In some embodiments, the first predetermined parameter is not less than 120°C.

[0025] As a result, the foaming layer expands as it gradually heats up during thermal runaway, filtering and blocking the combustible solid particles ejected from the pressure relief mechanism in a timely manner. At the same time, the foaming device is controlled not to start during normal circulation and affect the normal operation of the battery cell.

[0026] In some embodiments, the protective shell includes any one of ceramic, polytetrafluoroethylene, polyimide, polyphenylene sulfide, and polyetheretherketone; the temperature trigger layer includes any one of paraffin, polyethylene, and polypropylene, and the second predetermined parameter is in the range of 130°C to 150°C.

[0027] Because the second predetermined parameter is at an appropriate temperature, the expansion time can be more optimal, allowing for the filtration and isolation of solid particles in the early stages of thermal runaway. Furthermore, the material used in the protective shell is physically and chemically stable and heat-resistant, making it convenient for accommodating the foaming layer. The temperature-triggered layer comprises a temperature-sensitive material, such as a phase change material or a temperature-sensitive polymer, which ruptures, melts, or dissolves at the second predetermined parameter, prompting the foaming layer to form and fill the first accommodation space.

[0028] A second aspect of the embodiments of the present application provides a battery device comprising a plurality of battery cells as described in the first aspect of the embodiments of the present application.

[0029] Since the battery device includes a plurality of battery cells as described in the first aspect of the embodiment of the present application, the risk of thermal diffusion of the battery device can be reduced.

[0030] The third aspect of the embodiments of the present application provides an energy storage device, comprising a plurality of battery cells as described in the first aspect of the embodiments of the present application or a plurality of battery devices as described in the second aspect of the embodiments of the present application, wherein the battery cells or the battery devices are used to store or provide electrical energy.

[0031] A fourth aspect of the embodiments of the present application provides an energy storage system, comprising a power conversion device and the energy storage device described in the third aspect of the embodiments of the present application, wherein the power conversion device is used to electrically connect a power generation device and the energy storage device.

[0032] The fifth aspect of the embodiments of the present application provides a charging network, comprising a charging pile and the energy storage device described in the third aspect of the embodiments of the present application or the energy storage system described in the fourth aspect of the embodiments of the present application, wherein the energy storage device is used to provide electrical energy to the charging pile.

[0033] The beneficial effects of the embodiments of the present disclosure include: through this application, solid particulate matter can be filtered when the battery cell is depressurized, and the solid particulate matter sprayed out when the battery cell is depressurized can be reduced to a certain extent, and the adverse risks of secondary combustion, insulation failure, and environmental pollution of the sprayed solid particulate matter in the external environment of the battery cell can be reduced.

[0034] 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

[0035] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to denote the same components. In the drawings:

[0036] Figure 1 A schematic diagram of the structure of a charging network provided in some embodiments of the present application;

[0037] Figure 2 A schematic diagram of the structure of an energy storage system provided in some embodiments of the present application;

[0038] Figure 3 A schematic structural diagram of an energy storage device provided in some embodiments of the present application;

[0039] Figure 4 A schematic exploded perspective view of a battery device provided in some embodiments of the present application;

[0040] Figure 5 A schematic exploded perspective view of a battery cell provided in some embodiments of the present application;

[0041] Figure 6 A schematic diagram of the three-dimensional structure of a foaming device provided in some embodiments of the present application;

[0042] Figure 7 A schematic structural diagram of an end cap provided in some embodiments of the present application;

[0043] Figure 8 A schematic structural diagram of an end cap provided in some other embodiments of the present application;

[0044] Figure 9 A schematic structural diagram of a foaming device provided in some embodiments of the present application;

[0045] Figure 10 for Figure 9 Cross-sectional view at AA in the middle.

[0046] Description of Reference Numerals

[0047] 10. Battery cell; 11. Shell; 11A. First opening; 12. Electrode assembly; 12A. Tab; 12B. Main body; 13. End cap; 13A. Electrode terminal; 13B. Pressure relief valve; 13C. Liquid injection hole; 14. Insulator; 20. Foaming device; 21. Foaming layer; 22. Protective shell; 23. Overflow portion; 24. Temperature trigger layer; 25. Second opening; S1. First accommodating space; S2. Second accommodating space; 100. Battery device; 101. Box; 1000. Charging network; 2000. Energy storage system; 3000. Power generation device; 200. Energy storage device; 210. Energy storage box; 300. Charging pile; 400. Energy storage converter. DETAILED DESCRIPTION

[0048] The following embodiments of the technical solution of the present 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 the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0049] 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 for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" and any variations thereof in this document and the above-mentioned drawings are intended to cover non-exclusive inclusions.

[0050] In the description of the embodiments of this application, the technical terms "first," "second," "third," etc. are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise specifically defined.

[0051] 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.

[0052] 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.

[0053] In the description of the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings. They 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, operated or used in a specific orientation. Therefore, they should not be understood as limitations on the embodiments of the present application.

[0054] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connect," 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.

[0055] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, the technical term "contact" should be understood in a broad sense, and can be direct contact, contact through an intermediate medium layer, contact with essentially no interaction force between the two contacting parties, or contact with interaction force between the two contacting parties.

[0056] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, the technical terms "parallel" and "perpendicular" are allowed to have a certain degree of tolerance and / or error, including the situations of being approximately parallel and approximately perpendicular.

[0057] Below, this application is described in detail.

[0058] Currently, new energy batteries are increasingly being used in everyday life and industry. They are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric cars, as well as in a variety of fields such as aerospace. As the application of power batteries continues to expand, market demand is also growing.

[0059] In new energy vehicles equipped with batteries, the batteries can be used to provide power in whole or in part. In the field of energy storage, the batteries can be installed in the energy storage box or directly on the user side. In these application scenarios, when the battery cell thermal runaway occurs, the pressure can be released from the pressure relief mechanism. When the battery cell is depressurized, there is an undesirable situation of solid particles being ejected. The ejected solid particles usually have high temperature and conductivity, which may cause secondary combustion and insulation failure. Therefore, how to reduce the solid particles ejected when the battery cell is depressurized is one of the research and development topics in the industry.

[0060] After research and design, a foaming layer can be set at the position of the battery cell pressure relief channel and the pressure relief mechanism. The foaming layer has interconnected micropores, which can filter and block solid particles ejected with the gas, and will not block the normal flow of gas and will not affect the normal pressure relief of the pressure relief mechanism.

[0061] Based on such a design concept, the present application designs a battery cell, including a shell, which defines a first accommodation space and forms a first opening; an electrode assembly, which is accommodated in the first accommodation space; an end cover, which covers the first opening and is provided with a pressure relief mechanism, and a foaming device, which is arranged on a side of the end cover close to the electrode assembly along the first direction, and the foaming device includes a foaming layer and an overflow portion, the foaming layer is configured to expand when exceeding a first predetermined parameter, and the overflow portion is for the foaming layer to overflow.

[0062] Therefore, the foaming layer expands after exceeding the first predetermined parameter, and directly covers the pressure relief mechanism through the foaming layer, filtering and blocking the combustible particles ejected from the battery cell during thermal runaway, thereby reducing the solid particles ejected from the battery cell during pressure relief to a certain extent, reducing the adverse risks of secondary combustion, insulation failure, and environmental pollution of the ejected solid particles in the external environment of the battery cell, and preventing the spread of thermal runaway.

[0063] In the following examples, for the convenience of description,

[0064] The battery device 100 is described below with reference to the accompanying drawings.

[0065] Please refer to Figure 1 and Figure 3 , Figure 1 This is a schematic diagram of the structure of a charging network 1000 provided in some embodiments of the present application. Figure 3A schematic diagram of the structure of an energy storage device 200 provided in some embodiments of the present application. Embodiments of the present application provide a charging network 1000, which includes charging piles 300, which are used to charge electrical devices. Charging network 1000 may also include an energy storage device 200, which is electrically connected to charging piles 300 and is used to provide electrical energy to charging piles 300.

[0066] It should be noted that the charging pile 300 is electrically connected to the battery cells in the energy storage device 200 via a cable, and the battery cells can provide their stored energy to the charging pile 300. The charging pile 300 has a connector that can be connected to an electrical device to replenish energy. The application of the energy storage device 200 in the charging network 1000 can effectively improve the safety of the charging network 1000 and also help increase the flexibility of the charging network 1000 during deployment.

[0067] In a charging network 1000 , there may be one charging pile 300 , and the energy storage device 200 provides power to the one charging pile 300 ; there may also be multiple charging piles 300 , and the energy storage device 200 provides power to multiple charging piles 300 .

[0068] As an example, Figure 1 As shown, the charging network 1000 includes an energy storage device 200 and two charging piles 300 , and one energy storage device 200 provides power to the two charging piles 300 .

[0069] The energy storage device 200 may include a battery device 100 , which is electrically connected to the charging pile 300 so that the battery device 100 provides electrical energy to the charging pile 300 .

[0070] Please refer to Figure 2 and Figure 3 , Figure 2 A schematic diagram of the structure of an energy storage system 2000 provided in some embodiments of the present application. Embodiments of the present application provide an energy storage system 2000. The energy storage system 2000 includes an energy storage converter 400, which can be electrically connected to a power generation device 3000 to convert the electric power provided by the power generation device 3000. The energy storage system 2000 may also include an energy storage device 200, which is electrically connected to the energy storage converter 400. The energy storage converter 400 converts the electric energy provided by the power generation device 3000 into the energy storage device 200 for storage.

[0071] The power conversion device is connected between the power generation device 3000 and the energy storage device 200. The power generation device 3000 is used to generate electrical energy, and the power generation device 3000 is used to store the generated electrical energy in the energy storage device 200 via the power conversion device. The use of the energy storage device 200 in the energy storage system 2000 can effectively improve the operational safety of the energy storage system 2000. In a specific implementation, the power generation equipment can specifically include solar panels, hydroelectric power generation equipment, thermal power generation equipment, etc. The specific type of power generation equipment is not limited in this application.

[0072] As an example, Figure 2 As shown, the energy storage system 2000 includes an energy storage device 200 and an energy storage conversion device 400. The two power generation devices 3000 respectively transmit the generated electric energy to the energy storage conversion device 400, and the electric energy is introduced into the energy storage device 200 for storage through the energy storage conversion device 400.

[0073] Please refer to Figure 3 The energy storage device 200 includes an energy storage box 210 , in which the battery device 100 is disposed.

[0074] As an example, the energy storage device 200 may be an energy storage container, an energy storage cabinet, etc.

[0075] As an example, the energy storage device 200 can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems or temporary power supply systems. The energy storage power station can store electric energy during low power consumption periods and provide electric energy to relevant users or electrical equipment during peak power consumption periods. The wind energy collected by the wind turbines of the wind power generation system is converted into electric energy and then stored by the energy storage device 200. The solar power generation system can convert solar energy into electric energy, which is then stored by the energy storage device 200 and supplied to users in a timely manner. The mobile power system can supply power to relevant electrical equipment in places where the power grid power supply system cannot reach, such as remote mountainous areas, remote wilderness areas, etc. The temporary power supply system can provide power to users when the power supply is insufficient.

[0076] Figure 4 This is a schematic diagram of a three-dimensional exploded view of the battery device 100 provided in an embodiment of the present application. Figure 4 The battery device 100 includes a bottom plate, a cover, and at least one battery cell 10 . The cover is covered on the bottom plate to form a box 101 , thereby defining a storage space for the battery cell 10 .

[0077] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0078] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0079] A battery cell typically includes an electrode assembly. This assembly consists of a positive electrode, a negative electrode, and a separator. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0080] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0081] In some embodiments, the electrode assembly may be a wound structure, a laminated structure, or a mixed structure of wound and laminated structures.

[0082] In some embodiments, a battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0083] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, and a polygonal battery. The polygonal battery is, for example, a hexagonal battery, etc. There is no special limitation in this application.

[0084] In some embodiments, the housing can be either a sealed or unsealed structure. For example, in an unsealed structure, the housing protects the electrode assembly and includes a sealed bag between the housing and the electrode assembly, which encapsulates the electrode assembly and electrolyte. Specifically, the sealed bag can be a bag-shaped insulating member or an aluminum-plastic film. In a sealed structure, the housing encapsulates the electrode assembly, electrolyte, and other components.

[0085] The emissions from battery cells mentioned in this application include but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of isolation membranes, high-temperature and high-pressure gases produced by the reaction, flames, combustible solid particles, etc.

[0086] The battery apparatus mentioned in the embodiments of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include multiple battery cells, which are connected in series, parallel, or hybrid via a busbar.

[0087] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells. For example, the battery cell assembly may be a battery module, which is a battery module formed by arranging and securing multiple battery cells to form a single module. For example, a battery module may be formed by bundling multiple battery cells using cable ties.

[0088] In some embodiments, the battery device may be a battery pack, which includes a case and one or more battery cell assemblies, wherein the battery cell assemblies are housed in the case.

[0089] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box by fixing the battery module in the box.

[0090] As an example, the battery cell assembly may also be housed in the box by directly fixing the plurality of battery cells to the box.

[0091] As an example, the housing may include a first housing and a second housing. The first housing and the second housing engage to form an enclosed space within the housing to house the battery cell assembly. Enclosed here means covered or closed, and can be either sealed or unsealed. The first housing may be a top cover or a bottom plate.

[0092] As an example, the box may include a top cover, a frame, and a bottom plate, wherein the top cover and the bottom plate are respectively connected to the frame to form a closed space inside the box to accommodate the battery cell assembly.

[0093] Below, refer to Figures 5 to 10 Some embodiments of the present application are described in detail.

[0094] Figure 5 A schematic exploded perspective view of a battery cell provided in some embodiments of the present application; Figure 6 A schematic diagram of the three-dimensional structure of a foaming device provided in some embodiments of the present application; Figure 7 A schematic structural diagram of an end cap provided in some embodiments of the present application; Figure 8 A schematic structural diagram of an end cap provided in some other embodiments of the present application; Figure 9 A schematic structural diagram of a foaming device provided in some embodiments of the present application; Figure 10 for Figure 9 Cross-sectional view at AA in the middle.

[0095] In some embodiments of the present application, for ease of explanation, a first direction, a second direction, and a third direction are defined. The directions of the first direction, the second direction, and the third direction are intersecting directions. Here, intersecting directions includes perpendicularly intersecting directions. To facilitate understanding of the embodiments of the present application, the embodiments shown in Figures 3 to 8 are described using the example of directions of the first direction, the second direction, and the third direction intersecting directions perpendicularly. However, those skilled in the art should understand that the embodiments of the present application are not limited to the case where the three directions intersect perpendicularly. For ease of explanation, as shown by the arrows in Figures 3 to 8, the direction of arrow X is the first direction, the direction of arrow Y is the second direction, and the direction of arrow Z is the third direction. In a specific embodiment, the first direction may be the height direction of the battery cell, the second direction may be the length direction of the battery cell, and the third direction may be the thickness direction of the battery cell.

[0096] A first aspect of an embodiment of the present application provides a battery cell 10. In this embodiment, the battery cell 10 includes a housing 11, an electrode assembly 12, an end cap 13, and a foaming device 20. The housing 11 defines a first accommodation space S1 and is formed with a first opening 11A. The electrode assembly 12 is accommodated in the first accommodation space S1. The end cap 13 covers the first opening 11A and is provided with a pressure relief mechanism. The foaming device 20 is disposed on a side of the end cap 13 that is proximate to the electrode assembly 12 along a first direction. The foaming device 20 includes a foaming layer 21 and an overflow portion 23. The foaming layer 21 is configured to expand when exceeding a first predetermined parameter, and the overflow portion 23 allows the foaming layer to overflow.

[0097] It is understandable that the shell 11 is a component used to cooperate with the end cover 13 to form a storage space for the battery cell 10. The formed first storage space S1 can be used to accommodate the electrode assembly 12, electrolyte (not shown in the figure) and other components.

[0098] Optionally, the housing 11 may have a variety of shapes and sizes. The housing 11 may be cylindrical, rectangular, polygonal, or other shapes, with the polygonal prism being, for example, a hexagonal. It will be appreciated that the shape of the housing 11 may be determined based on the specific shape and size of the electrode assembly 12. For example, if the electrode assembly 12 has a cylindrical structure, a cylindrical housing 11 may be selected; if the electrode assembly 12 has a rectangular structure, a rectangular housing 11 may be selected.

[0099] Optionally, the housing 11 may have one or two first openings 11A. It is understood that if the housing 11 has one first opening 11A, then the end cap 13 may be one; if the housing 11 has two first openings 11A, then the end cap 13 may be two. The two end caps 13 respectively cover the two first openings 11A.

[0100] Optionally, the housing 11 and the end cover 13 may be independent components, and an opening may be provided on the housing 11 , and the end cover 13 may cover the opening to form a receiving space for the battery cell 10 .

[0101] Optionally, the end cap 13 and the shell 11 can be integrated. Specifically, the end cap 13 and the shell 11 can form a common connection surface before other components are inserted into the shell. When the interior of the shell 11 needs to be encapsulated, the end cap 13 is covered on the shell 11.

[0102] For example, in the embodiments of the present application, the description is primarily based on a case 11 having a hollow rectangular parallelepiped structure. Furthermore, the embodiments of the present application primarily use a case 11 having a hollow structure with an opening at one end as an example. However, the description of the embodiments of the present application is equally applicable to battery cells 10 of other shapes, and for the sake of brevity, they will not be detailed here.

[0103] It can be understood that the electrode assembly 12 is a component in the battery cell 10 where the electrochemical reaction occurs. One or more electrode assemblies 12 may be contained in the shell 11. The electrode assembly 12 is mainly formed by winding or stacking the positive electrode sheet and the negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet with active materials constitute the main body 12B of the electrode assembly 12, and the parts of the positive electrode sheet and the negative electrode sheet without active materials each constitute a tab 12A. The two tabs 12A can be located together at one end of the main body 12B or respectively at both ends of the main body 12B. During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tab 12A is connected to the electrode terminal 13A to form a current loop.

[0104] Optionally, the electrode assembly 12 is a wound structure or a laminated structure.

[0105] Optionally, the pressure relief mechanism may include a pressure relief valve 13B.

[0106] Illustratively, the pressure relief valve 13B may be integrally formed with the end cover 13 .

[0107] As another example, the pressure relief valve 13B may also be separately provided and connected to the end cover 13 .

[0108] In a specific embodiment, the pressure relief mechanism may include a pressure relief hole provided through the end cover 13 , and a pressure relief cover is provided on the end cover 13 to cover the pressure relief hole. The pressure relief cover can be destroyed, and the emissions from the battery cell 10 can be discharged through the pressure relief hole.

[0109] In other specific embodiments, the pressure relief valve 13B may also be a weak portion provided on the end cover 13 .

[0110] It can be understood that the foaming device 20 is arranged on the inner side of the end cover 13 .

[0111] Optionally, the foaming layer 21 may be in a solid state, a semi-liquid state, or a liquid state.

[0112] Optionally, the foaming layer 21 can be a multi-component foaming layer or a single-component foaming layer. It is understood that the foaming layer 21 expands in volume and forms cells after being heated.

[0113] In other embodiments, the foaming layer 21 may also be a mixture of a foaming matrix polymer, a foaming agent, a curing agent, a catalyst, etc., and expands by foaming.

[0114] It is understood that the foaming agent can generate gas to form cells in the foaming matrix polymer, and the curing agent solidifies the cell structure to form a porous foam layer. The embodiment of the present application does not limit the cell size.

[0115] It is understandable that the foamed layer may be an open-cell structure, that is, the cells are interconnected and gas can pass through.

[0116] Optionally, the pores are microporous structures, which can filter and block solid particles to a certain extent.

[0117] It is understandable that the particles ejected by thermal runaway may contain particles of battery electrode materials and carbonized products from the decomposition of the electrolyte. These particles may also contain heavy metals, which can pollute the environment and harm human health.

[0118] It is understandable that the particles ejected by thermal runaway may also contain incompletely burned electrolyte residue or combustible materials (such as carbonized particles). These high-temperature materials may reignite combustion in the air due to high temperature or static electricity, causing a secondary explosion.

[0119] It is understood that particulate matter may settle on the surface of circuit boards, connectors or other electronic components, causing insulation degradation, leading to short circuits or equipment failure.

[0120] Optionally, the foaming method of the foaming layer 21 can be physical foaming or chemical foaming.

[0121] Optionally, the overflow portion 23 may be a through hole, and the foaming layer 21 can overflow from the through hole after expansion.

[0122] Optionally, the first predetermined parameter may be temperature, pressure, current, pH value or the like.

[0123] Exemplarily, the first predetermined parameter is a temperature parameter.

[0124] Therefore, the foaming layer 21 foams and expands after exceeding the first predetermined parameter, and directly covers the pressure relief mechanism through the foaming layer, filtering and blocking the combustible particles ejected from the battery cell 10 during thermal runaway, thereby reducing the solid particles ejected from the battery cell 10 during pressure relief to a certain extent, reducing the adverse risks of secondary combustion, insulation failure, and environmental pollution of the ejected solid particles in the external environment of the battery cell 10, and preventing the spread of thermal runaway.

[0125] In an embodiment of the present application, the foaming device 20 includes a protective shell 22 , the overflow portion 23 is provided in the protective shell 22 , and the protective shell 22 defines a second accommodating space S2 , and the second accommodating space S2 accommodates the foaming layer 21 .

[0126] Optionally, the shape of the protective shell 22 can be a cylinder, a cuboid, a polygonal prism or other shapes, and the polygonal prism can be, for example, a hexagonal prism, etc. It is understood that the shape of the protective shell 22 can be determined according to the specific shape and size of the installation space inside the end cover 13.

[0127] For example, Figure 5 、 Figure 6 、 Figure 9 As shown, the foaming device 20 may be a rectangular parallelepiped structure.

[0128] Optionally, the second accommodating space S2 may fully accommodate the foaming layer 21 , or a portion of the space may be used to accommodate the foaming layer 21 , which is not limited in the embodiment of the present application.

[0129] Optionally, the foaming device 20 can be fixed to the end cover 13 by snapping, bonding, welding, etc.

[0130] Thus, the protective shell 22 can accommodate the foam layer 21 , so that the foam layer 21 does not interfere with the first accommodation space S1 where the electrode assembly 12 is located under normal conditions, thereby preventing it from affecting the normal cycle use of the battery cell 10 .

[0131] In an embodiment of the present application, the overflow portion 23 includes a second opening 25 and a temperature trigger layer 24. The second opening 25 is formed on at least one side of the protective shell 22 along the first direction. The temperature trigger layer 24 closes the second opening 25. The temperature trigger layer 24 is configured to connect the first accommodating space S1 and the second accommodating space S2 after exceeding the second predetermined parameter.

[0132] Optionally, the first predetermined parameter may be the same as or different from the second predetermined parameter.

[0133] Exemplarily, the second predetermined parameter may be a temperature parameter.

[0134] Optionally, the second opening 25 may be a regular shape such as a circle, an ellipse, a triangle, a rectangle, or may be an irregular shape.

[0135] Optionally, the protective shell 22 may have multiple second openings 25 , and the multiple second openings 25 may be arranged on both sides of the first direction, or may be all arranged on the same side.

[0136] For example, Figure 5 、 Figure 6 、 Figure 9 As shown, the protective shell 22 may have only one second opening 25 , and the second opening 25 is disposed toward the electrode assembly 12 .

[0137] It can be understood that the temperature triggering layer 24 is a layered structure and closes the second opening 25 .

[0138] Optionally, a projection area of ​​the temperature triggering layer 24 along the first direction may be larger than the second opening 25 , that is, the temperature triggering layer 24 covers the second opening 25 .

[0139] Optionally, the shape of the temperature triggering layer 24 may be the same as or different from that of the second opening 25 , which is not limited in the embodiment of the present application.

[0140] Optionally, the temperature trigger layer 24 may include a temperature-sensitive material film layer, which actively breaks, melts or dissolves when a second predetermined parameter is reached.

[0141] For example, the temperature trigger layer 24 may have at least one scratch to facilitate its rupture and release of the foaming layer 21 in the event of thermal runaway.

[0142] This helps the foaming layer 21 quickly fill the second accommodation space S2 during thermal runaway, filter solid particles, and reduce the number of solid particles that reach the pressure relief mechanism and are ejected from the pressure relief channel. At the same time, the foaming device 20 is controlled so as not to start during normal circulation and affect the normal operation of the battery cell 10.

[0143] In the embodiment of the present application, the foaming layer 21 includes a base material, a foaming agent and a foaming aid;

[0144] The matrix material includes any one of epoxy resin, silicone rubber, and polyamide;

[0145] The foaming agent includes any one of azodicarbonamide, diisopropyl azodicarboxylate, barium azodicarboxylate, dimethyl azodicarboxylate, and azoaminobenzene;

[0146] The foaming aid includes any one of zinc oxide, zinc peroxide, zinc carbonate, and lead oxide.

[0147] For example, the foaming layer 21 can be placed in the second receiving space S2 in a solid state. Figure 10 As shown, the foaming layer 21 can be a mixture of solid particles.

[0148] As another example, the foaming layer 21 may be loaded into the second receiving space S2 in a solution state.

[0149] Optionally, the foaming layer 21 may further include a curing agent, such as dicyandiamide.

[0150] It can be understood that the foaming aid is equivalent to a catalyst, which reduces the starting temperature of the foaming reaction.

[0151] It is understood that azo foaming agents (AC) are stable at room temperature, forming fine, evenly distributed, and interconnected cells. Their decomposition products are non-toxic, and the gases they produce are somewhat flame-retardant. Foaming aids activate the thermal decomposition reaction of the foaming agent, driving the foaming reaction toward lower temperatures.

[0152] In an embodiment of the present application, the first predetermined parameter is not less than 120°C.

[0153] It is understandable that the first predetermined parameter can be preset according to the thermal runaway temperature of different batteries. In this embodiment, 120°C is used as the thermal runaway trigger temperature. In other embodiments, the thermal runaway trigger temperature may not be 120°C, which is not listed in this application.

[0154] As a result, the foaming layer 21 expands as it gradually heats up during thermal runaway, filtering and blocking the combustible solid particles ejected from the pressure relief mechanism in a timely manner, while controlling the foaming device 20 so as not to start during normal circulation and affect the normal operation of the battery cell 10.

[0155] In an embodiment of the present application, the protective shell 22 includes any one of ceramic, polytetrafluoroethylene, polyimide, polyphenylene sulfide, and polyetheretherketone; the temperature trigger layer 24 includes any one of paraffin, polyethylene, and polypropylene, and the second predetermined parameter is in the range of 130°C to 150°C.

[0156] It is understandable that the protective shell 22 is made of high temperature resistant and corrosion resistant material and is fixed to the inner side of the end cover 13 , forming a sealed second accommodation space S2 inside for storing the foam layer 21 .

[0157] Optionally, the protective shell 22 may be made of a composite material, such as a ceramic-polymer composite layer.

[0158] Exemplarily, the second predetermined parameter may be a temperature parameter, specifically any one of 130°C, 132°C, 134°C, 136°C, 138°C, 140°C, 142°C, 144°C, 146°C, 148°C, and 150°C. Other values ​​are not listed.

[0159] It is understandable that paraffin is a solid-liquid phase change material, which can turn into a semi-liquid or liquid state when the phase change temperature is reached, so that the expanded foaming layer 21 overflows from the position of the temperature triggering layer 24.

[0160] Because the second predetermined parameter is at an appropriate temperature, the expansion time is more optimal, allowing for the filtration and isolation of solid particles in the early stages of thermal runaway. Furthermore, the material used for protective shell 22 is physically and chemically stable and heat-resistant, conveniently accommodating foam layer 21. Temperature-triggered layer 24 comprises a temperature-sensitive material, such as a phase change material or a temperature-sensitive polymer. It ruptures, melts, or dissolves at the second predetermined parameter, prompting the foam layer to form and fill first accommodation space S1.

[0161] In the embodiment of the present application, when projected along the first direction onto a projection plane perpendicular to the first direction, the projection of the foaming device 20 does not overlap with the projection of the pressure relief mechanism.

[0162] Optionally, the foaming device 20 may be arranged away from the pressure relief valve 13B without affecting the pressure relief of the pressure relief valve 13B.

[0163] Optionally, the foaming device 20 can be arranged away from the liquid injection hole 13C without affecting the liquid injection.

[0164] For example, the foaming device 20 may be disposed around the pressure relief valve 13B.

[0165] As another example, the foaming device 20 may be provided at the edge of the end cover 13 along the second direction.

[0166] As another example, the foaming device 20 may be provided at an edge of the end cover 13 along the third direction.

[0167] This improves the flexibility of the placement of the foaming device 20 and effectively utilizes the space inside the end cap 13. Furthermore, the foaming layer can fill the gap in the first accommodation space S1 or partially cover the pressure relief mechanism, further reducing the number of solid particles that reach the pressure relief mechanism from the pressure relief channel and are ejected, thereby reducing the impact on the pressure relief capability of the battery cell 10.

[0168] In an embodiment of the present application, the battery cell 10 includes an electrode terminal 13A, which is arranged on the end cover 13. The electrode terminal 13A protrudes from the end cover 13 on the side close to the electrode assembly 12 along the first direction, and an insulating member 14 is provided on the side of the pressure relief mechanism close to the electrode assembly 12 along the first direction; along the second direction, the foaming device 20 is arranged between the insulating member 14 and the electrode terminal 13A, and the second direction is perpendicular to the first direction.

[0169] Optionally, the electrode terminal 13A may be provided on the end cover 13 or on the housing 11 .

[0170] For example, Figure 7As shown, the insulating member 14 is arranged inside the pressure relief mechanism and has a plurality of through holes.

[0171] For example, the insulating member 14 may be a plastic member or a rubber member.

[0172] Optionally, a lower plastic may be provided inside the end cover 13 , and along the first direction, the lower plastic may be provided between the insulating member 14 and the end cover 13 .

[0173] Optionally, the lower plastic can be arranged inside the end cover 13 avoiding the insulating member 14 .

[0174] In this way, the space between the insulating member 14 and the electrode terminal 13A can be fully utilized without occupying additional internal space of the battery, thereby improving the utilization rate of the internal space of the housing 11 and reducing the impact on the capacity of the battery cell 10.

[0175] In the embodiment of the present application, the electrode assembly 12 includes a tab 12A and a main body 12B, and the foaming device 20 is located between the tab 12A and the end cover 13 along the first direction.

[0176] In some embodiments, as Figure 5 As shown, at least one electrode terminal 13A is provided on the end cap 13, and the electrode terminal 13A is electrically connected to the electrode tab 12A. The electrode terminal 13A can be directly connected to the electrode tab 12A or indirectly connected to the electrode tab 12A through a current collecting member.

[0177] For example, Figure 5 As shown, there is a gap between the tab 12A and the end cap 13, which can serve as an exhaust / pressure relief channel during pressure relief. Gas is discharged from the pressure relief channel through the pressure relief mechanism to the outside of the battery cell 10. The foaming device 20 is arranged between the tab 12A and the end cap 13. The foamed layer formed after foaming fills the pressure relief channel to filter solid particles.

[0178] Therefore, the foaming device 20 is located close to the pressure relief mechanism, and the foaming layer can more effectively fill the pressure relief channel, thereby improving the filtering and blocking effects on solid particles.

[0179] In an embodiment of the present application, when projected along the first direction onto a projection plane perpendicular to the first direction, at least part of the projection of the foaming device 20 overlaps with the projection of the pressure relief mechanism; the protective shell 22 has second openings 25 on both sides along the first direction, and the temperature triggering layer 24 closes each second opening 25.

[0180] For example, Figure 8 As shown, the foaming device 20 is arranged inside the pressure relief mechanism to filter the gas passing through the pressure relief mechanism along the first direction.

[0181] It is understandable that the protective shell 22 has second openings 25 on both sides along the first direction, so that the battery cell 10 can release pressure.

[0182] In other embodiments, the material of the protective shell 22 may be the same as that of the temperature-triggered layer 24 , and may rupture or melt during thermal runaway without affecting the pressure relief of the battery cell 10 .

[0183] Since the projection of the foaming device 20 partially overlaps with the projection of the pressure relief mechanism, it is beneficial for the foaming layer to directly cover the pressure relief mechanism area, forming a continuous foaming layer at the pressure relief mechanism to prevent solid particles from escaping. The gas can be discharged from the pressure relief mechanism through the area where the projections do not overlap and the position of the second opening 25, reducing the impact on the pressure relief capacity of the battery cell 10.

[0184] A second aspect of the embodiments of the present application provides a battery device 100 . In the embodiments of the present application, the battery device 100 includes a plurality of battery cells 10 according to the first aspect of the embodiments of the present application.

[0185] For example, Figure 4 As shown, the battery device 100 may be a battery pack, which includes a box 101 and a plurality of battery cells 10 . The battery cells 10 are accommodated in the box 101 .

[0186] As an example, the battery cells 10 may be combined into a battery module, and the battery cells 10 may be accommodated in the box body 101 by fixing the battery module in the box body 101 .

[0187] Since the battery device 100 includes a plurality of battery cells 10 according to the first aspect of the embodiment of the present application, the risk of thermal diffusion of the battery device 100 can be reduced.

[0188] The third aspect of the embodiments of the present application provides an energy storage device 200, comprising a plurality of battery cells as described in the first aspect of the embodiments of the present application or a plurality of battery devices 100 as described in the second aspect of the embodiments of the present application, wherein the battery cells or the battery devices 100 are used to store or provide electrical energy.

[0189] For example, Figure 3 As shown, the energy storage device 200 includes an energy storage box 210, and a battery device 100 is disposed in the energy storage box 210. The embodiment of the present application does not limit the number of battery devices 100.

[0190] A fourth aspect of the embodiments of the present application provides an energy storage system 2000 , comprising a power conversion device and the energy storage device 200 described in the third aspect of the embodiments of the present application, wherein the power conversion device is used to electrically connect a power generation device 3000 and the energy storage device 200 .

[0191] For example, Figure 2 As shown, energy storage system 2000 includes an energy storage and conversion device 400, which can be electrically connected to a power generation device 3000 to convert the power provided by the power generation device 3000. Energy storage system 2000 can also include an energy storage device 200, which is electrically connected to the energy storage and conversion device 400. The energy storage and conversion device 400 converts the power provided by the power generation device 3000 into energy storage device 200 for storage.

[0192] For example, Figure 2 As shown, the energy storage system 2000 includes an energy storage device 200 and an energy storage conversion device 400. The two power generation devices 3000 respectively transmit the generated electric energy to the energy storage conversion device 400, and the electric energy is introduced into the energy storage device 200 for storage through the energy storage conversion device 400.

[0193] A fifth aspect of the embodiments of the present application provides a charging network 1000, comprising a charging pile 300 and the energy storage device 200 described in the third aspect of the embodiments of the present application or the energy storage system 2000 described in the fourth aspect of the embodiments of the present application, wherein the energy storage device 200 is used to provide electrical energy to the charging pile 300.

[0194] For example, Figure 1 As shown, an embodiment of the present application provides a charging network 1000, which includes a charging pile 300, which is used to charge electrical devices. The charging network 1000 may also include an energy storage device 200, which is electrically connected to the charging pile 300 and is used to provide electrical energy to the charging pile 300.

[0195] The specific solutions of the embodiments of the present application are described below with reference to the accompanying drawings.

[0196] This embodiment provides a battery cell 10 with a foaming device 20 positioned beneath the pressure relief mechanism or in another space beneath the end cap 13. When the internal battery temperature exceeds a threshold, the temperature-sensitive trigger layer ruptures, triggering an internal chemical foaming reaction. The foaming layer 21 expands to 20-50 times its original volume within a few seconds, forming a porous structure that rapidly fills the internal voids of the battery, filters emitted combustible solid particles, and reduces the safety risks of thermal runaway and thermal diffusion.

[0197] The foaming device 20 includes a protective layer, a temperature triggering layer 24 and a foaming layer 21 .

[0198] The protective layer (shell) is made of a high-temperature resistant and corrosion-resistant composite material (such as a ceramic-polymer composite layer) and is fixed under the battery pressure relief mechanism (or other positions under the battery top cover), forming a sealed second accommodating space S2 inside for storing the foam layer 21.

[0199] The temperature trigger layer 24 is a thin layer of material covering the second opening 25 and is a heat-sensitive material. When the internal temperature of the battery cell 10 is greater than or equal to the melting point of the trigger layer, the temperature trigger layer 24 ruptures, melts or softens.

[0200] In some embodiments, the second accommodation space S2 contains only the fast-foaming layer 21 (such as a two-component modified epoxy resin foam or other composite foaming layer 21 ), which can rapidly expand to fill the battery cavity and play a certain role in isolating combustible solid particles and temperature.

[0201] In other embodiments, the second containing space S2 contains a matrix material and a catalyst.

[0202] The matrix material is a composite of a thermosetting polymer (such as epoxy resin or silicone rubber) and a foaming agent (such as azodicarbonamide); the catalyst (such as metal oxide) is an active substance released when triggered by heat or pressure, which triggers a rapid polymerization and foaming reaction when in contact with the matrix material.

[0203] In a specific embodiment, the matrix material and / or catalyst in the foaming layer 21 can be enclosed in microcapsules made of a thermosensitive material. The microcapsules can be made of the same material as the temperature-triggering layer 24. When the battery temperature rises due to a short circuit, overcharge, or mechanical damage, the temperature-triggering layer 24 ruptures, and the microcapsules made of the thermosensitive material also rupture, allowing the catalyst within to come into contact with the matrix material, triggering the chemical foaming reaction. Unless otherwise specified, all embodiments and alternative embodiments of this application can be combined to form new technical solutions.

[0204] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0205] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of protection requested by the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of protection requested.

Claims

1. A battery cell, characterized in that: include a housing defining a first accommodation space and having a first opening; an electrode assembly, the electrode assembly being accommodated in the first accommodation space; An end cover, the end cover covers the first opening, and the end cover is provided with a pressure relief mechanism, A foaming device is provided on a side of the end cover close to the electrode assembly along the first direction, and the foaming device includes a foaming layer and an overflow portion. The foaming layer is configured to expand when exceeding a first predetermined parameter, and the overflow portion is for the foaming layer to overflow.

2. The battery cell according to claim 1, wherein: The foaming device includes a protective shell, the overflow portion is provided in the protective shell, the protective shell defines a second accommodating space, and the second accommodating space accommodates the foaming layer.

3. The battery cell according to claim 2, characterized in that: The overflow portion includes a second opening and a temperature trigger layer. The second opening is formed on at least one side of the protective shell along the first direction. The temperature trigger layer closes the second opening. The temperature trigger layer is configured to connect the first storage space and the second storage space after exceeding a second predetermined parameter.

4. The battery cell according to claim 1, wherein: When projected along the first direction onto a projection plane perpendicular to the first direction, the projection of the foaming device does not overlap with the projection of the pressure relief mechanism.

5. The battery cell according to claim 4, characterized in that The battery cell includes an electrode terminal, the electrode terminal is provided on the end cover, and a side of the electrode terminal close to the electrode assembly along the first direction protrudes from the end cover, and an insulating member is provided on a side of the pressure relief mechanism close to the electrode assembly along the first direction; The foaming device is disposed between the insulating member and the electrode terminal along a second direction, and the second direction is perpendicular to the first direction.

6. The battery cell according to claim 4, characterized in that The electrode assembly includes a tab and a main body, and the foaming device is located between the tab and the end cover along the first direction.

7. The battery cell according to claim 3, characterized in that Projecting along the first direction onto a projection plane perpendicular to the first direction, at least a portion of the projection of the foaming device overlaps with the projection of the pressure relief mechanism; The protective shell has the second openings on both sides along the first direction, and the temperature triggering layer closes each of the second openings.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The first predetermined parameter is not less than 120°C.

9. The battery cell according to claim 3, characterized in that: The protective shell comprises any one of ceramic, polytetrafluoroethylene, polyimide, polyphenylene sulfide, and polyetheretherketone; The temperature trigger layer includes any one of paraffin, polyethylene, and polypropylene, and the second predetermined parameter is in the range of 130°C to 150°C.

10. A battery device, characterized in that: The invention comprises a plurality of battery cells according to any one of claims 1 to 9.

11. An energy storage device, characterized in that: The battery cell comprises a plurality of battery cells according to any one of claims 1 to 9 or a plurality of battery devices according to claim 10, wherein the battery cells or the battery device are used to store or provide electrical energy.

12. An energy storage system, characterized in that: It comprises a power conversion device and the energy storage device according to claim 11, wherein the power conversion device is used to electrically connect the power generation device and the energy storage device.

13. A charging network, characterized in that: It comprises a charging pile and the energy storage device according to claim 11 or the energy storage system according to claim 12, wherein the energy storage device is used to provide electrical energy for the charging pile.

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