Battery cell, battery and electrical device

Abstract

A battery cell (100), a battery (200) and an electrical device (300). The battery cell (100) comprises: an electrode assembly (10); a casing (20) configured to accommodate the electrode assembly (10), the casing (20) comprising a first wall portion (21); and a pressure relief portion (30) arranged on the first wall portion (21), wherein a score groove (31) is formed in the pressure relief portion (30), a rupture initiation section (32) and an extension section (33) which are connected to each other are formed in the bottom of the score groove (31), and the pressure relief portion (30) is configured to enable, when the internal pressure or temperature of the casing (20) reaches a threshold, the rupture initiation section (32) to rupture prior to the extension section (33).

Description

Battery cells, batteries, and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 202410265191.8 and application date of March 7, 2024, and claims the priority of the above-mentioned Chinese patent application. The entire content of the above-mentioned Chinese patent application is hereby introduced into this application as a reference. Technical Field

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

[0004] In the related art, a battery cell includes a shell and an electrode assembly. The electrode assembly is arranged in the shell, and the shell is provided with a pressure relief portion. When the battery cell expands, the pressure relief portion may crack and fail to flip normally, resulting in the battery cell being unable to release pressure in time, causing the end cover of the battery cell to explode, thereby reducing the safety of the battery cell.

[0005] Summary of the Invention

[0006] The present application aims to solve one of the technical problems in the related art at least to a certain extent.

[0007] To this end, one object of the present application is to provide a battery cell.

[0008] Another object of the present application is to provide a battery.

[0009] Another object of the present application is to provide an electrical device.

[0010] In a first aspect, an embodiment of the present application provides a battery cell, comprising:

[0011] electrode assembly;

[0012] a housing for accommodating the electrode assembly, the housing comprising a first wall portion;

[0013] The pressure relief portion is arranged on the first wall portion, and a notched groove is formed on the pressure relief portion. The bottom of the notched groove is formed with a connected cracking section and an extension section. The pressure relief portion is configured so that when the internal pressure or temperature of the shell reaches a threshold, the cracking section cracks before the extension section.

[0014] In the above technical solution, by setting the rupture section and the extension section, when the internal pressure or temperature of the shell reaches the threshold, the rupture section will rupture first, and then the extension section will rupture, thereby reducing the difficulty of flipping the pressure relief part, allowing the battery cell to release pressure in time, reducing the risk of battery cell explosion, and improving the safety of battery cell use.

[0015] In a second aspect, an embodiment of the present application further provides a battery comprising the above-mentioned battery cell.

[0016] In the above technical solution, the battery cell is provided with a cracking section and an extension section. When the internal pressure or temperature of the shell reaches a threshold value, the cracking section cracks first and then the extension section cracks, thereby reducing the difficulty of flipping the pressure relief part, allowing the battery cell to release pressure in time, reducing the risk of battery cell explosion, and improving the safety of battery cell use, thereby improving the safety of battery use.

[0017] In a third aspect, an embodiment of the present application further provides an electrical device comprising the above-mentioned battery.

[0018] In the above technical solution, the electrical device includes the above-mentioned battery, which improves the safety of the electrical device.

[0019] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a schematic diagram of an electrical device according to an embodiment of the present application;

[0021] FIG2 is a schematic diagram of a battery according to an embodiment of the present application;

[0022] FIG3 is a schematic diagram of a battery cell having a pressure relief portion disposed on an end cap according to an embodiment of the present application;

[0023] FIG4 is an exploded view of a battery cell according to an embodiment of the present application;

[0024] FIG5 is a schematic diagram of a pressure relief portion according to a first embodiment of the present application;

[0025] FIG6 is a front view of the pressure relief portion according to the first embodiment of the present application;

[0026] FIG7 is a cross-sectional view at AA in FIG6;

[0027] Figure 8 is an enlarged view of point C in Figure 7;

[0028] FIG9 is a cross-sectional view at point BB in FIG6 ;

[0029] Figure 10 is an enlarged view of point D in Figure 9;

[0030] Figure 11 is an enlarged view of point E in Figure 9;

[0031] FIG12 is a schematic diagram of a pressure relief portion according to a second embodiment of the present application;

[0032] FIG13 is a front view of a pressure relief portion according to a second embodiment of the present application;

[0033] FIG14 is a schematic diagram of a pressure relief portion according to a third embodiment of the present application;

[0034] FIG15 is a front view of a pressure relief portion according to a third embodiment of the present application;

[0035] FIG16 is a schematic diagram showing a trapezoidal cross-section of a notched groove of a pressure relief portion according to an embodiment of the present application;

[0036] FIG17 is a schematic diagram showing a semicircular cross-section of a notched groove of a pressure relief portion according to an embodiment of the present application;

[0037] FIG18 is a schematic diagram showing a triangular cross-section of a notched groove of a pressure relief portion according to an embodiment of the present application;

[0038] FIG19 is a schematic diagram showing a cross section of a notched groove of a pressure relief portion having an oblong shape according to an embodiment of the present application;

[0039] FIG20 is a schematic diagram showing notched grooves formed on opposite sides of a pressure relief portion according to an embodiment of the present application;

[0040] FIG21 is a schematic diagram showing a pressure relief portion of a battery cell provided on a housing according to an embodiment of the present application. DETAILED DESCRIPTION

[0041] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0042] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application 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 the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0043] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the 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.

[0044] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0045] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0046] In 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 should not constitute any limitation on this application.

[0047] The term "plurality" used in this application refers to two or more (including two).

[0048] 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.

[0049] 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.

[0050] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel or in hybrid through a busbar.

[0051] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0052] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0053] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0054] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0055] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, the safety performance of the battery also needs to be considered.

[0056] To ensure the safety of a battery cell, a pressure relief device can be installed on the outer shell of the battery cell. In the event of thermal runaway, the pressure inside the battery cell is released through the pressure relief device, thereby improving the safety of the battery cell. During pressure relief, there is a risk that the pressure relief device may crack and fail to flip properly, preventing the battery cell from releasing pressure in a timely manner. This could cause the end cap of the battery cell to explode, reducing the safety of the battery cell.

[0057] In view of this, an embodiment of the present application provides a battery cell, including an electrode assembly and a shell, the shell is used to accommodate the electrode assembly, the shell includes a first wall portion, a pressure relief portion is arranged on the first wall portion, the pressure relief portion is formed with a notch groove, the bottom of the notch groove is formed with a connected cracking section and an extension section, the pressure relief portion is configured so that when the internal pressure or temperature of the shell reaches a threshold value, the cracking section cracks before the extension section, and then the extension section cracks, thereby reducing the difficulty of flipping the pressure relief portion, facilitating the flipping of the pressure relief portion, allowing the battery cell to release pressure in time, reducing the risk of the end cover of the battery cell exploding, and improving the safety of the battery cell.

[0058] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0059] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0060] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0061] Please refer to Figure 1, which is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application. A battery 200 is disposed within the vehicle, and battery 200 can be located at the bottom, front, or rear of the vehicle. Battery 200 can be used to power the vehicle, for example, as the vehicle's operating power source.

[0062] The vehicle may further include a controller 400 and a motor 500 . The controller 400 is used to control the battery 200 to supply power to the motor 500 , for example, to meet the vehicle's power requirements for starting, navigating, and driving.

[0063] In some embodiments of the present application, the battery 200 can serve not only as an operating power source for the vehicle, but also as a driving power source for the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0064] Please refer to Figure 2, which is an exploded view of a battery 200 provided in some embodiments of the present application. The battery 200 includes a battery cell 100 and a box 201, wherein the box 201 is used to accommodate the battery cell 100.

[0065] The housing 201 is a component that houses the battery cells 100 and provides storage space for the battery cells 100. The housing 201 can have various structures. In some embodiments, the housing 201 can include a first body 202 and a second body 203. The first body 202 and the second body 203 overlap to define a storage space for the battery cells 100. The first body 202 and the second body 203 can have various shapes, such as a rectangular parallelepiped or a cylinder. The first body 202 can be a hollow structure with one side open, and the second body 203 can be a hollow structure with one side open. The open side of the second body 203 overlaps the open side of the first body 202, forming the housing 201 with storage space. Alternatively, the first body 202 can be a hollow structure with one side open, and the second body 203 can be a plate-like structure. The second body 203 overlaps the open side of the first body 202, forming the housing 201 with storage space. As an example, the battery cell 100 can be a cylindrical battery cell 100, a prismatic battery cell 100, a soft-pack battery cell 100 or a battery cell 100 of other shapes. The prismatic battery cell 100 includes a square-shell battery cell 100, a blade-shaped battery cell 100, and a polygonal battery 200. The polygonal battery 200 is, for example, a hexagonal battery 200, etc. There is no special limitation in this application.

[0066] In the battery 200, there can be one or more battery cells 100. If there are multiple battery cells 100, the multiple battery cells 100 can be connected in series, parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 100. Multiple battery cells 100 can be connected in series, parallel, or in a hybrid connection to form a battery 200 module. The multiple battery modules 200 can then be connected in series, parallel, or in a hybrid connection to form a single unit and housed within the housing 201. Alternatively, all battery cells 100 can be directly connected in series, parallel, or in a hybrid connection, and then the entire unit formed by all battery cells 100 can be housed within the housing 201.

[0067] 3 and 4 , FIG3 is a schematic diagram of a battery cell 100 according to some embodiments of the present invention; FIG4 is an exploded view of a battery cell 100 according to some embodiments of the present invention. The battery cell 100 may include a housing 20 and an electrode assembly 10 .

[0068] The housing 20 is used to house the electrode assembly 10 and other components such as the electrolyte. The housing 20 can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite housing 20), or an aluminum-plastic film. As an example, the housing 20 can include a shell 23 and an end cap 24.

[0069] The housing 23 may be a hollow structure with an opening at one end, or a hollow structure with openings at opposite ends. The housing 23 may be made of a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, and the like.

[0070] The end cap 24 is a component that closes the opening of the shell 23 to isolate the internal environment of the battery cell 100 from the external environment. The end cap 24 and the shell 23 together define a storage space for accommodating the electrode assembly 10, electrolyte, and other components. The end cap 24 can be connected to the shell 23 by welding or crimping to close the opening of the shell 23. The shape of the end cap 24 can be adapted to the shape of the outer shell 20. For example, if the shell 23 is a rectangular parallelepiped structure, the end cap 24 is a rectangular plate structure adapted to the shell 23. The material of the end cap 24 can also be various, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0071] In the battery cell 100, there can be one or two end caps 24. In embodiments where the housing 23 is a hollow structure with openings at both ends, two end caps 24 can be provided. The two end caps 24 respectively close the two openings of the housing 23, and the two end caps 24 and the housing 23 together define a storage space. In embodiments where the housing 23 is a hollow structure with an opening at one end, there can be one end cap 24 provided. The end cap 24 closes the opening at one end of the housing 23, and the end cap 24 and the housing 23 together define a storage space.

[0072] The electrode assembly 10 includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell 100, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0073] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material region disposed on at least one surface of the positive electrode current collector, wherein the positive electrode active material region has a positive electrode active material.

[0074] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material region is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0075] In some embodiments, the negative electrode may be a negative electrode sheet, which may include a negative electrode current collector and a negative electrode active material region disposed on at least one surface of the negative electrode current collector.

[0076] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material region is provided on either one or both of the two facing surfaces of the negative electrode current collector.

[0077] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0078] In some embodiments, the electrode assembly 10 further includes a separator disposed between the positive electrode and the negative electrode.

[0079] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0080] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0081] In some embodiments, the battery cell 100 further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte may be selected based on needs. The electrolyte may be liquid, gel, or solid.

[0082] In some embodiments, the electrode assembly 10 is a wound structure in which the positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0083] In some embodiments, the electrode assembly 10 is a laminated structure.

[0084] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0085] As an example, multiple positive electrode sheets may be provided, and the negative electrode sheet is folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0086] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0087] As an example, multiple separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0088] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0089] In some embodiments, the shape of the electrode assembly 10 can be flat or polygonal.

[0090] In some embodiments, the electrode assembly 10 is provided with tabs, which can conduct current from the electrode assembly 10. The tabs include a positive tab and a negative tab.

[0091] The battery cell 100 may further include an electrical connection terminal 25, which may be disposed on the housing 20. The electrical connection terminal 25 is configured to electrically connect to the tab of the electrode assembly 10 to output electrical energy from the battery cell 100. The electrical connection terminal 25 may be directly connected to the tab, for example, by direct welding. The electrical connection terminal 25 may also be indirectly connected to the tab, for example, by a current collecting member. The current collecting member may be a metal conductor, such as copper, iron, aluminum, steel, or an aluminum alloy.

[0092] As shown in Figure 3, taking the shell 23 as an example of a hollow structure with an opening at one end, two electrical connection terminals 25 can be set on the end cover 24. The two electrical connection terminals 25 are respectively a positive electrical connection terminal 25 (i.e., a positive electrode column) and a negative electrical connection terminal 25 (i.e., a negative electrode column). The positive electrical connection terminal 25 is electrically connected to the positive electrode ear, and the negative electrical connection terminal 25 is electrically connected to the negative electrode ear.

[0093] The battery cell 100 according to an embodiment of the present application is described below with reference to FIG. 5 to FIG. 21 .

[0094] According to an embodiment of the present application, the battery cell 100 includes: an electrode assembly 10; a shell 20 for accommodating the electrode assembly 10, the shell 20 including a first wall portion 21; a pressure relief portion 30, the pressure relief portion 30 being arranged on the first wall portion 21, the pressure relief portion 30 forming a notch groove 31, the bottom of the notch groove 31 forming a connected rupture section 32 and an extension section 33, the pressure relief portion 30 being configured such that when the internal pressure or temperature of the shell 20 reaches a threshold value, the rupture section 32 ruptures before the extension section 33.

[0095] Among them, the electrode assembly 10 includes a positive electrode sheet and a negative electrode sheet, for example: the electrode assembly 10 includes at least one positive electrode sheet and at least one negative electrode sheet, at least one positive electrode sheet and at least one negative electrode sheet are stacked to form the electrode assembly 10, at least a portion of the positive electrode sheet and at least a portion of the negative electrode sheet can be stacked along a first direction, when the battery cell 100 is placed in the direction shown in Figure 3, the first direction refers to the Y direction in Figure 3.

[0096] The electrode assembly 10 may also be of a wound type, where the positive electrode sheet and the negative electrode sheet of the electrode assembly 10 are stacked with the separator and then wound into a shape, with the positive electrode sheet portion and the negative electrode sheet portion stacked along a first direction.

[0097] The housing 20 defines an installation cavity, and the electrode assembly 10 of the battery cell 100 is installed in the installation cavity. The housing 20 includes a first wall portion 21 , which serves as a cavity wall of the installation cavity.

[0098] The pressure relief portion 30 is provided on the first wall portion 21. This portion can be an explosion-proof valve, or the first wall portion 21 can be scored to form the pressure relief portion 30. The pressure relief portion 30 is formed with a scored groove 31. The bottom of the scored groove 31 is formed with a connected rupture section 32 and an extension section 33. In other words, the bottom wall of the scored groove 31 is formed with a connected rupture section 32 and an extension section 33. When the internal pressure or temperature of the housing 20 reaches a threshold, the rupture section 32 initiates rupture before the extension section 33, i.e., the rupture section 32 breaks open before the extension section 33. When the internal pressure or temperature of the mounting cavity reaches a certain threshold, the scored groove 31 of the pressure relief portion 30 opens, allowing gas and substances inside the battery cell 100 to be discharged from the pressure relief portion 30, achieving a pressure relief effect. The threshold design varies depending on design requirements and may depend on the materials of one or more of the positive and negative electrode sheets, electrolyte, and separator in the battery cell 100.

[0099] When the internal pressure or temperature of the shell 20 reaches a threshold value, the cracking section 32 first cracks and tears the bottom wall of the notched groove 31. After the cracking section 32 cracks, it cracks along the extension section 33, that is, the bottom wall of the notched groove 31 cracks along the extension section 33. Since the internal pressure of the shell 20 is high, under the action of the internal pressure of the shell 20, part of the structure of the pressure relief part 30 is conducive to flipping outward, which can make the battery cell 100 depressurized in time, reduce the risk of explosion of the battery cell 100, and improve the safety of the battery cell 100.

[0100] In the above technical solution, by providing the rupture section 32 and the extension section 33, when the internal pressure or temperature of the outer shell 20 reaches a threshold value, the rupture section 32 ruptures first, and then the extension section 33 ruptures, thereby reducing the difficulty of flipping the pressure relief portion 30, allowing the battery cell 100 to release pressure in a timely manner, reducing the risk of explosion of the battery cell 100, and improving the safety of the battery cell 100.

[0101] According to some embodiments of the present application, as shown in Figures 5, 12 and 14, a main section 34 is also formed at the bottom of the notch groove 31, and an extension section 33 is connected between the cracking section 32 and the main section 34. The thickness of the extension section 33 is less than the thickness of the cracking section 32, and the thickness of the cracking section 32 is less than the thickness of the main section 34.

[0102] The bottom of the scored groove 31 also forms a main section 34. In other words, the bottom wall of the scored groove 31 also forms a main section 34. The extension section 33 is connected between the crack initiation section 32 and the main section 34. As an example, one end of the crack initiation section 32 is connected to one end of the extension section 33, one end of the main section 34 is connected to the other end of the extension section 33, and the other end of the crack initiation section 32 is connected to the other end of the main section 34. As another example, there are two extension sections 33, one extension section 33 is connected between one end of the crack initiation section 32 and one end of the main section 34, and the other extension section 33 is connected between the other end of the crack initiation section 32 and the other end of the main section 34. The thickness of the extension section 33 is smaller than that of the rupture initiation section 32, which in turn is smaller than that of the main section 34. By making the thickness of the extension section 33 smaller than that of the rupture initiation section 32, the rupture initiation section 32 can initiate rupture before the extension section 33. Furthermore, after the rupture initiation section 32 ruptures, the internal pressure of the housing 20 facilitates the rupture of the extension section 33, thereby further facilitating the outward rotation of a portion of the pressure relief portion 30, allowing for timely pressure relief from the battery cell 100, further reducing the risk of explosion and enhancing the safety of the battery cell 100. By making the thickness of the rupture initiation section 32 smaller than that of the main section 34, the main section 34 maximizes its structural strength. After the rupture initiation section 32 and the extension section 33 rupture, the risk of the main section 34 rupturing is reduced, thereby reducing the risk of the pressure relief portion 30 flying out of the housing 20 under the internal pressure, thereby reducing the risk of damage to objects or injuries, further enhancing the safety of the battery cell 100.

[0103] It should be noted that the extension section 33, the crack initiation section 32 and the main section 34 can all be set to a uniform thickness, or the extension section 33, the crack initiation section 32 and the main section 34 can all be set to a non-uniform thickness, or part of the extension section 33, the crack initiation section 32 and the main section 34 are set to a uniform thickness, and another part of the extension section 33, the crack initiation section 32 and the main section 34 are set to a non-uniform thickness. This application takes the example of the extension section 33 being set to a non-uniform thickness and the crack initiation section 32 being set to a uniform thickness. The thickness of the extension section 33 is the average thickness of the extension section 33, and the thickness values ​​of each area of ​​the crack initiation section 32 are equal.

[0104] In the above technical solution, by making the thickness of the extension section 33 smaller than that of the rupture initiation section 32, the rupture initiation section 32 can be achieved before the extension section 33 ruptures. Furthermore, after the rupture initiation section 32 ruptures, the internal pressure of the housing 20 facilitates the rupture of the extension section 33, thereby further facilitating the outward rotation of part of the pressure relief portion 30, allowing for timely pressure relief from the battery cell 100, further reducing the risk of explosion of the battery cell 100 and further improving the safety of the battery cell 100. By making the thickness of the rupture initiation section 32 smaller than that of the main section 34, the main section 34 maximizes its structural strength. After the rupture initiation section 32 and the extension section 33 rupture, the risk of the main section 34 rupturing is reduced, thereby reducing the risk of the pressure relief portion 30 structure flying out of the housing 20 under the internal pressure, reducing the risk of damage to objects or injuries, and further improving the safety of the battery cell 100.

[0105] According to some embodiments of the present application, a ratio of the thickness of the crack initiation segment 32 to the thickness of the extension segment 33 is greater than or equal to 1.05 and less than or equal to 2.1.

[0106] The thickness ratio of the rupture section 32 to the extension section 33 affects the functionality of the pressure relief portion 30. When the ratio is too small (i.e., the thicknesses of the rupture section 32 and the extension section 33 are designed to be similar), the extension section 33 cannot effectively assist in cracking the bottom of the notch 31. This can easily result in only the rupture section 32 cracking after the pressure relief portion 30 is opened, causing the battery cell 100 to explode due to insufficient pressure relief area. Therefore, the thickness ratio of the rupture section 32 to the extension section 33 has a minimum value. When the ratio is too large, the extension section 33 is prone to non-air pressure-driven mechanical damage, i.e., cracking, under normal operating conditions (such as vibration, shock, and respiratory fatigue). This can cause abnormal leakage of the battery cell 100. Therefore, the thickness ratio of the rupture section 32 to the extension section 33 has a maximum value.

[0107] In the present application, the ratio of the thickness of the rupture section 32 to the thickness of the extension section 33 is greater than or equal to 1.05 and less than or equal to 2.1. As some examples, the ratio of the thickness of the rupture section 32 to the thickness of the extension section 33 can be set to values ​​such as 1.05, 2, and 2.1. Such a setting can help the extension section 33 to assist in the bottom cracking of the notch groove 31, reduce the occurrence of only the rupture section 32 cracking after the pressure relief section 30 is opened, reduce the occurrence of explosion of the battery cell 100, and reduce the risk of the extension section 33 cracking under normal use conditions, thereby reducing the risk of leakage of the battery cell 100.

[0108] In the above technical solution, the ratio of the thickness of the rupture section 32 to the thickness of the extension section 33 is greater than or equal to 1.05 and less than or equal to 2.1, which is conducive to the extension section 33 to assist the bottom of the notch groove 31 to crack, thereby reducing the occurrence of only the rupture section 32 cracking after the pressure relief part 30 is opened, reducing the occurrence of explosion of the battery cell 100, and also reducing the risk of the extension section 33 cracking under normal use conditions, reducing the risk of leakage of the battery cell 100.

[0109] According to some embodiments of the present application, the thickness of the crack initiation segment 32 is greater than or equal to 0.05 mm and less than or equal to 0.31 mm.

[0110] The thickness of the crack initiation section 32 can be set to values ​​such as 0.05 mm, 0.06 mm, 0.1 mm, 0.2 mm, and 0.31 mm, as long as the thickness of the crack initiation section 32 is 0.05 mm, 0.31 mm, or any value between 0.05 mm and 0.31 mm. If the thickness of the crack initiation section 32 is less than 0.05 mm, the crack initiation section 32 is too thin, and the crack initiation section 32 is prone to cracking due to mechanical damage under long-term use. If the thickness of the crack initiation section 32 is greater than 0.31 mm, the crack initiation section 32 is too thick, and when the internal pressure or temperature of the housing 20 reaches a threshold, the crack initiation section 32 is prone to not cracking in time. Therefore, in the present application, by making the thickness of the rupture segment 32 greater than or equal to 0.05 mm and less than or equal to 0.31 mm, the thickness of the rupture segment 32 can be made appropriate, thereby reducing the risk of the rupture segment 32 cracking due to mechanical damage under long-term application conditions. In addition, when the internal pressure or temperature of the shell 20 reaches a threshold, it is conducive to the timely rupture of the rupture segment 32, so that the battery cell 100 can be depressurized in time.

[0111] In the above technical solution, by making the thickness of the rupture section 32 greater than or equal to 0.05 mm and less than or equal to 0.31 mm, the thickness of the rupture section 32 can be made appropriate, thereby reducing the risk of the rupture section 32 cracking due to mechanical damage under long-term application conditions. In addition, when the internal pressure or temperature of the shell 20 reaches a threshold, it is conducive to the timely rupture of the rupture section 32, so that the battery cell 100 can be depressurized in time.

[0112] According to some embodiments of the present application, as shown in FIG. 6 , FIG. 13 and FIG. 15 , the scoring groove 31 is an annular structure, and the inner edge of the scoring groove 31 defines a pressure relief area 35 .

[0113] Among them, the notched groove 31 is an annular structure. Along the width direction of the notched groove 31, the notched groove 31 has an outer edge and an inner edge. The inner edge of the notched groove 31 can define a pressure relief zone 35. After the starting section 32 is cracked, the extension section 33 is cracked under the action of the internal pressure of the outer shell 20, which is more conducive to the pressure relief zone 35 of the pressure relief part 30 to flip outward, so that the pressure relief part 30 forms an opening, which can enable the battery cell 100 to release pressure from the opening in time, further reduce the risk of explosion of the battery cell 100, and further improve the safety of the battery cell 100.

[0114] In the above technical solution, by setting the notched groove 31 as an annular structure, the inner edge of the notched groove 31 defines a pressure relief zone 35. After the starting section 32 is cracked, the extension section 33 is cracked under the action of the internal pressure of the outer shell 20, which is more conducive to the pressure relief zone 35 of the pressure relief part 30 to flip outward, so that the pressure relief part 30 forms an opening, which can enable the battery cell 100 to release pressure from the opening in time, further reducing the risk of explosion of the battery cell 100, and further improving the safety of the battery cell 100.

[0115] According to some embodiments of the present application, as shown in FIG6 , FIG13 and FIG15 , the pressure relief zone 35 is in the shape of an elongated strip, and the ratio of the maximum length of the pressure relief zone 35 to the maximum width of the pressure relief zone 35 is greater than 1.2 and less than 5.5.

[0116] The pressure relief zone 35 is an elongated strip-shaped structure. As an example, as shown in FIG6 , the pressure relief zone 35 is an oblong structure. As another example, as shown in FIG13 and FIG15 , the pressure relief zone 35 is a rectangular structure. Taking the oblong structure of the pressure relief zone 35 in FIG6 as an example, the maximum length of the pressure relief zone 35 along the length direction of the pressure relief zone 35 is L mm, and the maximum width of the pressure relief zone 35 along the width direction of the pressure relief zone 35 is W mm. The ratio of the maximum length of the pressure relief zone 35 to the maximum width of the pressure relief zone 35 is the aspect ratio of the pressure relief zone 35. This parameter characterizes the degree to which the shape of the explosion-proof valve deviates from the square / circular shape. The ratio of the maximum length of the pressure relief zone 35 to the maximum width of the pressure relief zone 35 is greater than 1.2 and less than 5.5. The ratio of the maximum length of the pressure relief zone 35 to the maximum width of the pressure relief zone 35 can be 1.3, 1.5, 2, 5, 5.4, etc. As long as the ratio of the maximum length of the pressure relief zone 35 to the maximum width of the pressure relief zone 35 is between 1.2 and 5.5, it is acceptable.

[0117] It should be noted that when the ratio of the maximum length of the pressure relief zone 35 to the maximum width of the pressure relief zone 35 increases, the shape of the pressure relief zone 35 approaches an elongated strip, and the uneven strain distribution of the pressure relief zone 35 under pressure drive becomes more severe, which can easily cause abnormal cracking of the pressure relief portion 30 under long-term operating conditions. Therefore, considering the long-term reliability design requirements of the pressure relief portion 30, the ratio of the maximum length of the pressure relief zone 35 to the maximum width of the pressure relief zone 35 has a design maximum value. When the ratio of the maximum length of the pressure relief zone 35 to the maximum width of the pressure relief zone 35 decreases, the shape of the pressure relief zone 35 approaches a square or circular shape, and the strain distribution of the notches at different positions on the notch groove 31 becomes closer to consistency, resulting in increased strength. This is not conducive to the normal cracking and pressure relief of the notch at the bottom of the notch groove 31, affecting the normal functionality of the pressure relief portion 30. The ratio of the maximum length of the pressure relief zone 35 to the maximum width of the pressure relief zone 35 has a design minimum value.

[0118] In the present application, by making the ratio of the maximum length of the pressure relief zone 35 to the maximum width of the pressure relief zone 35 greater than 1.2 and less than 5.5, it is beneficial for the strain distribution of the pressure relief zone 35 under pressure drive to be uniform, and under long-term use conditions, the risk of abnormal cracking of the pressure relief part 30 is reduced. In addition, it is also beneficial for the strain distribution of the notches at different positions of the notch groove 31 to be different. When the internal pressure or temperature of the shell 20 reaches the threshold, it is beneficial for the cracking section 32 to crack earlier than the extension section 33, which is beneficial for the normal cracking and pressure relief of the notch at the bottom of the notch groove 31, thereby improving the working reliability of the pressure relief part 30.

[0119] According to some embodiments of the present application, as shown in Figures 5 and 6, the scoring groove 31 includes two first straight groove segments 36 and two first arc-shaped groove segments 37, and the two ends of each first straight groove segment 36 are respectively connected to the two first arc-shaped groove segments 37 to make the scoring groove 31 constructed into a ring shape. The length of the first straight groove segment 36 is greater than the length of the first arc-shaped groove segment 37. A cracking section 32 is formed at the bottom of at least one first straight groove segment 36, and an extension section 33 is formed at the bottom of at least one first arc-shaped groove segment 37.

[0120] As shown in Figure 6, the scored groove 31 includes two first straight groove segments 36 and two first arcuate groove segments 37. The first straight groove segments 36 can be straight or quasi-straight. The first arcuate groove segments 37 can be arc-shaped. The two first straight groove segments 36 are oppositely spaced apart. The two first straight groove segments 36 can be parallel to each other and oppositely spaced apart. Each first straight groove segment 36 is connected to two first arcuate groove segments 37 at both ends. The two first straight groove segments 36 and the two first arcuate groove segments 37 form a closed annular structure, which can give the scored groove 31 a ring shape or an oblong shape. The length of the first straight groove segment 36 is greater than that of the first arcuate groove segment 37, thereby forming the pressure relief area 35 in an elongated strip shape. A crack initiation section 32 is formed at the bottom of at least one first straight groove segment 36. In other words, a crack initiation section 32 is formed at the bottom of one first straight groove segment 36, or both first straight groove segments 36. At least one first arcuate slot segment 37 has an extension segment 33 formed at its bottom. In other words, one first arcuate slot segment 37 has an extension segment 33 formed at its bottom, or both first arcuate slot segments 37 have extension segments 33 formed at their bottoms. This application uses an example in which one first straight slot segment 36 has a crack initiation segment 32 formed at its bottom, and both first arcuate slot segments 37 have extension segments 33 formed at their bottoms. When one first straight slot segment 36 has a crack initiation segment 32 formed at its bottom, the other first straight slot segment 36 has a main body segment 34 formed at its bottom. As an example, the entire bottom area of ​​one first straight slot segment 36 is formed with the crack initiation segment 32, the entire bottom area of ​​the other first straight slot segment 36 is formed with the main body segment 34, and the entire bottom area of ​​each first arcuate slot segment 37 is formed with an extension segment 33.

[0121] When the internal pressure or temperature of the shell 20 reaches a threshold value, the cracking section 32 first cracks, tearing the bottom wall of the first straight groove section 36. After the cracking section 32 cracks, it cracks along the extension section 33 at the first arc-shaped groove section 37. Since the internal pressure of the shell 20 is high, under the action of the internal pressure of the shell 20, it is more conducive to the outward flipping of the pressure relief area 35, which can make the battery cell 100 depressurized in time, reduce the risk of explosion of the battery cell 100, and improve the safety of the battery cell 100.

[0122] In the above technical solution, the notched groove 31 includes two first straight groove sections 36 and two first arc-shaped groove sections 37. When the internal pressure or temperature of the shell 20 reaches a threshold value, the cracking section 32 first cracks and tears the bottom wall of the first straight groove section 36. After the cracking section 32 cracks, it cracks along the extension section 33 at the first arc-shaped groove section 37. Since the internal pressure of the shell 20 is high, under the action of the internal pressure of the shell 20, it is more conducive to the outward flipping of the pressure relief zone 35, which can make the battery cell 100 depressurized in time, reduce the risk of explosion of the battery cell 100, and improve the safety of the battery cell 100.

[0123] According to some embodiments of the present application, as shown in Figure 12, the scoring groove 31 includes two second straight groove segments 38 and two third straight groove segments 39, and the two ends of each second straight groove segment 38 are respectively connected to the two third straight groove segments 39 to make the scoring groove 31 constructed into a ring shape, the length of the second straight groove segment 38 is greater than the length of the third straight groove segment 39, and a cracking section 32 is formed at the bottom of at least one second straight groove segment 38, and an extension section 33 is formed at the bottom of at least one third straight groove segment 39.

[0124] The scored groove 31 includes two second linear groove segments 38 and two third linear groove segments 39. The second linear groove segments 38 can be straight or quasi-straight, while the third linear groove segments 39 can be straight or quasi-straight. The two second linear groove segments 38 are spaced apart from each other and can be parallel to each other. The two third linear groove segments 39 are spaced apart from each other and can be parallel to each other. Each second linear groove segment 38 is connected to two third linear groove segments 39 at both ends. The two second linear groove segments 38 and the two third linear groove segments 39 form a closed annular structure, allowing the scored groove 31 to be configured in an annular or rectangular shape. The length of the second linear groove segment 38 is greater than that of the third linear groove segment 39, resulting in the pressure relief area 35 being elongated. A crack initiation section 32 is formed at the bottom of at least one second linear groove segment 38. In other words, a crack initiation section 32 may be formed at the bottom of one second linear groove segment 38 or both second linear groove segments 38. At least one third straight slot segment 39 has an extension section 33 formed at its bottom. In other words, a crack initiation section 32 is formed at the bottom of one third straight slot segment 39, or both third straight slot segments 39 have crack initiation sections 32 formed at their bottoms. This application uses an example in which a second straight slot segment 38 has a crack initiation section 32 formed at its bottom, and both third straight slot segments 39 have extension sections 33 formed at their bottoms. When a second straight slot segment 38 has a crack initiation section 32 formed at its bottom, the other second straight slot segment 38 has a main section 34 formed at its bottom. As an example, the entire bottom area of ​​one second straight slot segment 38 is formed with the crack initiation section 32, the entire bottom area of ​​the other second straight slot segment 38 is formed with the main section 34, and the entire bottom area of ​​each third straight slot segment 39 is formed with an extension section 33.

[0125] When the internal pressure or temperature of the shell 20 reaches a threshold value, the cracking section 32 first cracks, tearing the bottom wall of the second straight groove section 38. After the cracking section 32 cracks, it cracks along the extension section 33 at the third straight groove section 39. Since the internal pressure of the shell 20 is high, under the action of the internal pressure of the shell 20, it is more conducive to the outward flipping of the pressure relief area 35, which can make the battery cell 100 depressurized in time, reduce the risk of explosion of the battery cell 100, and improve the safety of the battery cell 100.

[0126] In the above technical solution, the notched groove 31 includes two second straight groove segments 38 and two third straight groove segments 39. When the internal pressure or temperature of the outer shell 20 reaches a threshold value, the cracking segment 32 first cracks and tears the bottom wall of the second straight groove segment 38. After the cracking segment 32 cracks, it cracks along the extension segment 33 at the third straight groove segment 39. Since the internal pressure of the outer shell 20 is high, under the action of the internal pressure of the outer shell 20, it is more conducive to the outward flipping of the pressure relief zone 35, which can make the battery cell 100 depressurized in time, reduce the risk of explosion of the battery cell 100, and improve the safety of the battery cell 100.

[0127] According to some embodiments of the present application, as shown in FIG. 14 and FIG. 15 , the scoring groove 31 further includes a second arcuate groove segment 391 , and the second straight groove segment 38 is connected to the third straight groove segment 39 via the second arcuate groove segment 391 .

[0128] In which, an extension section 33 can be formed at the bottom of the second arc-shaped slot segment 391, the second arc-shaped slot segment 391 can be circular, and the second arc-shaped slot segment 391 is connected between the second straight line slot segment 38 and the connected third straight line slot segment 39. As an example, a second arc-shaped slot segment 391 is connected between each second straight line slot segment 38 and the connected third straight line slot segment 39, so that the second straight line slot segment 38 is connected to the third straight line slot segment 39 through the second arc-shaped slot segment 391. By connecting the second arc-shaped slot segment 391 between the second straight slot segment 38 and the third straight slot segment 39, a smooth transition can be made between the connection between the second straight slot segment 38 and the connected third straight slot segment 39, thereby reducing the risk of premature cracking of the pressure relief portion 30 due to stress concentration. Moreover, when the internal pressure or temperature of the outer shell 20 reaches a threshold value, after the cracking segment 32 cracks, it is convenient for the cracking segment 32 to expand the crack toward the extension segment 33, further reducing the difficulty of flipping the pressure relief zone 35, allowing the battery cell 100 to be depressurized in time, further reducing the risk of explosion of the battery cell 100, and further improving the safety of the battery cell 100.

[0129] In the above technical solution, the second arc-shaped slot segment 391 is connected between the second straight slot segment 38 and the third straight slot segment 39, so that the connection between the second straight slot segment 38 and the connected third straight slot segment 39 can be smoothly transitioned, reducing the risk of premature cracking of the pressure relief portion 30 due to stress concentration. Moreover, when the internal pressure or temperature of the outer shell 20 reaches the threshold, after the cracking segment 32 cracks, it is convenient for the cracking segment 32 to expand the crack toward the extension segment 33, further reducing the difficulty of flipping the pressure relief zone 35, so that the battery cell 100 can be depressurized in time, further reducing the risk of explosion of the battery cell 100, and further improving the safety of the battery cell 100.

[0130] According to some embodiments of the present application, as shown in FIG. 14 and FIG. 15 , the second arc-shaped slot segment 391 is configured as an arc, and the chamfer radius of the second arc-shaped slot segment 391 is greater than or equal to 1 mm.

[0131] The second arcuate groove segment 391 is configured as an arc, and the chamfer radius of the second arcuate groove segment 391 is greater than or equal to 1 mm. The chamfer radius of the second arcuate groove segment 391 can be 1 mm, 1.5 mm, 2 mm, etc. The upper limit of the chamfer radius of the second arcuate groove segment 391 can be reasonably set according to actual conditions. By setting the chamfer radius of the second arcuate groove segment 391 to be greater than or equal to 1 mm, the connection between the second straight groove segment 38 and the connected third straight groove segment 39 can be made smoother, further reducing the risk of premature cracking of the pressure relief portion 30 due to stress concentration. Moreover, when the internal pressure or temperature of the housing 20 reaches a threshold, the cracking of the cracking initiation segment 32 is more easily extended to the extension segment 33, further reducing the difficulty of flipping the pressure relief zone 35, allowing the battery cell 100 to be depressurized in a timely manner, further reducing the risk of explosion of the battery cell 100, and further improving the safety of the battery cell 100.

[0132] In the above technical solution, by setting the chamfer radius of the second arc-shaped groove segment 391 to be greater than or equal to 1 mm, the connection between the second straight groove segment 38 and the connected third straight groove segment 39 can be made smoother, further reducing the risk of premature cracking of the pressure relief portion 30 due to stress concentration. Moreover, when the internal pressure or temperature of the outer shell 20 reaches the threshold, after the cracking segment 32 cracks, it is easier for the cracking segment 32 to expand toward the extension segment 33, further reducing the difficulty of flipping the pressure relief zone 35, allowing the battery cell 100 to be depressurized in time, further reducing the risk of explosion of the battery cell 100, and further improving the safety of the battery cell 100.

[0133] According to some embodiments of the present application, the crack initiation segment 32 is a straight line segment extending along a first direction; or the crack initiation segment 32 is a straight line segment extending along a second direction, and the second direction is perpendicular to the first direction.

[0134] The electrode assembly 10 includes a positive electrode sheet and a negative electrode sheet. For example, the electrode assembly 10 includes at least one positive electrode sheet and at least one negative electrode sheet. The at least one positive electrode sheet and at least one negative electrode sheet are stacked to form the electrode assembly 10. At least a portion of the positive electrode sheet and at least a portion of the negative electrode sheet can be stacked along a first direction. When the battery cell 100 is placed in the orientation shown in FIG3 , the first direction refers to the Y direction in FIG3 . The electrode assembly 10 can also be a wound type. The positive electrode sheet and the negative electrode sheet of the electrode assembly 10 are stacked with a separator and then wound into a shape. Parts of the positive electrode sheet and parts of the negative electrode sheet are stacked along the first direction. Because the parts of the positive electrode sheet and the negative electrode sheet are stacked along the first direction, when the electrode assembly 10 expands, most of the expansion of the electrode assembly 10 is reflected in the first direction. Furthermore, the housing 20 can also include two second wall portions 22 connected to the first wall portion 21. The two second wall portions 22 are located on both sides of the electrode assembly 10 along the first direction.

[0135] As an example, the crack initiation segment 32 is a straight segment extending along the first direction, that is, the crack initiation segment 32 extends along the first direction, which is conducive to the crack initiation segment 32 preferentially extending to the segment 33 to initiate cracking.

[0136] As another example, as shown in Figure 3, the rupture initiation segment 32 is a straight segment extending in a second direction, which is perpendicular to the first direction. When the battery cell 100 is positioned in the orientation shown in Figure 3, the second direction refers to the X direction in Figure 3. When the electrode assembly 10 expands, the majority of the expansion occurs in the first direction. Therefore, by configuring the rupture initiation segment 32 as a straight segment extending in the second direction, the force applied to the rupture initiation segment 32 is greater than that applied to the extension segment 33. This facilitates rupture of the rupture initiation segment 32 before the extension segment 33, allowing for timely pressure relief in the battery cell 100 and further reducing the risk of explosion.

[0137] In the above technical solution, by configuring the rupture initiation section 32 as a straight segment extending along the first direction, the rupture initiation section 32 is facilitated to initiate rupture before the extension section 33. By configuring the rupture initiation section 32 as a straight segment extending along the second direction, the force applied to the rupture initiation section 32 is greater than the force applied to the extension section 33, further facilitating the rupture initiation section 32 to initiate rupture before the extension section 33, thereby timely decompressing the battery cell 100 and further reducing the risk of explosion of the battery cell 100.

[0138] According to some embodiments of the present application, the pressure relief portion 30 is integrally formed with the first wall portion 21; or, the pressure relief portion 30 and the first wall portion 21 are separately provided, the first wall portion 21 is provided with a through hole, and the pressure relief portion 30 is installed in the through hole.

[0139] When the pressure relief portion 30 is integrally formed with the first wall portion 21, a notch 31 can be provided on the first wall portion 21, forming a weak area of ​​the first wall portion 21 in the region where the notch 31 is provided. This simplifies the molding of the pressure relief portion 30 and reduces production costs. In the above technical solution, by integrally forming the pressure relief portion 30 and the first wall portion 21, the molding of the pressure relief portion 30 is simplified, which can reduce the number of components comprising the battery cell 100, simplify the structure of the battery cell 100, and reduce the manufacturing cost of the battery cell 100.

[0140] Alternatively, as shown in FIG21 , the pressure relief portion 30 is provided separately from the first wall portion 21 . The pressure relief portion 30 and the outer shell 20 are two separate components that are separately molded and then assembled together. Specifically, the pressure relief portion 30 may be a component such as an explosion-proof disk, an explosion-proof valve, or a safety valve. The pressure relief portion 30 may be attached to the first wall portion 21 by bonding, welding, or the like. The first wall portion 21 is provided with a through-hole, and the pressure relief portion 30 is attached to the through-hole. When the internal pressure or temperature of the outer shell 20 reaches a threshold, the pressure relief portion 30 opens at least a portion of the through-hole, and the exhaust medium within the battery cell 100 is discharged through the through-hole to relieve the pressure within the battery cell 100. In the above technical solution, by constructing the pressure relief portion 30 and the first wall portion 21 as separate components, it is convenient to provide the pressure relief portion 30 on the outer shell 20 , with low manufacturing difficulty and high efficiency, thereby improving the production efficiency of the battery cell 100.

[0141] As an example, taking the pressure relief portion 30 as an explosion-proof disc, the explosion-proof disc is a sheet having at least a portion of its strength less than that of the first wall portion 21. The explosion-proof disc covers the through-hole and is welded to the first wall portion 21. When the internal pressure or temperature of the housing 20 reaches a threshold, the explosion-proof disc is at least partially destroyed, thereby opening at least a portion of the through-hole to release the pressure inside the battery cell 100.

[0142] According to some embodiments of the present application, as shown in Figure 21, the housing 20 includes: a shell 23 and an end cover 24, at least one side of the shell 23 has an opening, the end cover 24 is connected to the shell 23 and is used to close the opening, and the first wall portion 21 is formed on the shell 23.

[0143] The shell 23 may be a hollow structure with an opening at one end, or a hollow structure with openings at two opposite ends. The shell 23 may be in various shapes, such as a prismatic shape. The end cap 24 is a component that closes the opening of the shell 23 to isolate the internal environment of the battery cell 100 from the external environment. The end cap 24 and the shell 23 together define a mounting cavity for accommodating the electrode assembly 10, the electrolyte, and other components. The shape of the end cap 24 may be compatible with the shape of the shell 23. For example, if the shell 23 is a rectangular parallelepiped structure, the end cap 24 may be a rectangular plate-shaped structure that is compatible with the shell 23. For another example, if the shell 23 is a cylindrical structure, the end cap 24 may be a circular plate-shaped structure that is compatible with the shell 23. The material of the end cap 24 may also be various, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the end cap 24 and the shell 23 may be the same or different.

[0144] In an embodiment where the housing 23 is open at one end, one end cap 24 may be provided. In an embodiment where the housing 23 is open at two opposite ends, two end caps 24 may be provided, each of which closes the two openings of the housing 23 and defines a mounting cavity together with the housing 23.

[0145] The shell 23 has a first wall portion 21 and a second wall portion 22. The first wall portion 21 is formed on the shell 23. The pressure relief portion 30 can be integrally formed with the shell 23 or can be separately provided with the shell 23. By providing the pressure relief portion 30 on the shell 23, the structure of the end cover 24 can be simplified, and at the same time, it is convenient to shorten the distance between the pressure relief portion 30 and the main body of the electrode assembly 10, thereby shortening the path of the discharge medium flowing to the pressure relief portion 30 during pressure relief, shortening the time for the discharge medium to reach the pressure relief portion 30, and improving the timeliness of the pressure relief of the battery cell 100, thereby effectively improving the reliability of the battery cell 100.

[0146] In the above technical solution, the first wall portion 21 is formed in the shell 23, which can simplify the structure of the end cover 24 and facilitate shortening the distance between the pressure relief portion 30 and the main body of the electrode assembly 10. This can shorten the path of the discharge medium flowing to the pressure relief portion 30 during pressure relief, shorten the time for the discharge medium to reach the pressure relief portion 30, and improve the timeliness of the pressure relief of the battery cell 100, thereby effectively improving the reliability of the battery cell 100.

[0147] According to some embodiments of the present application, two opposite sides of the housing 23 have openings, and the two end covers 24 are used to close the openings on the corresponding sides.

[0148] In the embodiment where the housing 23 has openings formed at opposite ends, two end caps 24 may be provided. The two end caps 24 respectively close the two openings of the housing 23, and the two end caps 24 and the housing 23 together define a mounting cavity. Furthermore, the end caps 24 are provided with electrical connection terminals 25, which are electrically connected to the positive electrode sheet or the negative electrode sheet. The electrical connection terminal 25 can be a part of the end cover 24, or the electrical connection terminal 25 can be a pole mounted on the end cover 24; there are usually two electrical connection terminals 25, one electrical connection terminal 25 is a positive pole and is electrically connected to the pole tab of the positive pole sheet, and the other electrical connection terminal 25 is a negative pole and is electrically connected to the pole tab of the negative pole sheet to input or output the electrical energy of the battery cell 100. The electrical connection terminal 25 and the pole tab can be directly connected, for example, the electrical connection terminal 25 and the pole tab are directly welded, and the electrical connection terminal 25 and the pole tab can also be indirectly connected, for example, the electrical connection terminal 25 and the pole tab are indirectly connected through a current collecting component, and the current collecting component can be a metal conductor, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0149] In the above technical solution, the shell 23 has openings on both sides thereof, and the two end covers 24 are used to close the openings on the corresponding sides, which can jointly define the installation cavity. In addition, it is convenient for manufacturing and forming the shell 23, and it is convenient for the electrode assembly 10 to lead out the pole ears from both ends, thereby facilitating the separation and arrangement of the two electrical connection terminals 25, thereby reducing the risk of short circuit of the battery cell 100.

[0150] According to some embodiments of the present application, as shown in FIG. 21 , the first wall portion 21 is used to support the electrode assembly 10 and is located below the electrode assembly 10 .

[0151] The shell 23 has a shell bottom wall opposite to and spaced apart from the end cover 24 . The shell bottom wall is configured as a first wall portion 21 . The first wall portion 21 can support the electrode assembly 10 .

[0152] In the above technical solution, the electrode assembly 10 is supported by the first wall portion 21 , so that the electrode assembly 10 can be stably installed in the installation cavity of the housing 20 .

[0153] According to some embodiments of the present application, as shown in Figures 3 and 4, the housing 20 includes: a shell 23 and an end cover 24, at least one side of the shell 23 has an opening, the end cover 24 is connected to the shell 23 and is used to close the opening, and the first wall portion 21 is formed on the end cover 24.

[0154] The shell 23 may be a hollow structure with an opening at one end, or a hollow structure with openings at two opposite ends. The shell 23 may be in various shapes, such as a prismatic shape. The end cap 24 is a component that closes the opening of the shell 23 to isolate the internal environment of the battery cell 100 from the external environment. The end cap 24 and the shell 23 together define a mounting cavity for accommodating the electrode assembly 10, the electrolyte, and other components. The shape of the end cap 24 may be compatible with the shape of the shell 23. For example, if the shell 23 is a rectangular parallelepiped structure, the end cap 24 may be a rectangular plate-shaped structure that is compatible with the shell 23. For another example, if the shell 23 is a cylindrical structure, the end cap 24 may be a circular plate-shaped structure that is compatible with the shell 23. The material of the end cap 24 may also be various, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the end cap 24 and the shell 23 may be the same or different.

[0155] In an embodiment where the housing 23 is open at one end, one end cap 24 may be provided. In an embodiment where the housing 23 is open at two opposite ends, two end caps 24 may be provided, each of which closes the two openings of the housing 23 and defines a mounting cavity together with the housing 23.

[0156] In the above technical solution, by arranging the pressure relief portion 30 on the end cover 24 , the structure of the shell 23 can be simplified and the production efficiency of the shell 23 can be improved.

[0157] As shown in FIG5 , the pressure relief portion 30 of the first embodiment is an oblong shape. As shown in FIG12 , the pressure relief portion 30 of the second embodiment is a rectangular shape. As shown in FIG14 , a schematic diagram of the pressure relief portion 30 of the third embodiment is shown. Compared with the pressure relief portion 30 of the second embodiment, the pressure relief portion 30 of the third embodiment is provided with a second arcuate groove segment 391.

[0158] As shown in FIG11 , the cross-section of the notched groove 31 is square. As shown in FIG16 , the cross-section of the notched groove 31 is trapezoidal. As shown in FIG17 , the cross-section of the notched groove 31 is semicircular. As shown in FIG18 , the cross-section of the notched groove 31 is triangular. As shown in FIG19 , the cross-section of the notched groove 31 is oblong. As shown in FIG20 , notched grooves 31 are formed on both sides of the pressure relief portion 30. The notched grooves 31 on both sides of the pressure relief portion 30 are arranged opposite to each other, and the bottom of the notched groove 31 is formed between the two notched grooves 31 on both sides. The two notched grooves 31 on both sides share the bottom of the same notched groove 31.

[0159] According to some embodiments of the present application, the present application further provides a battery 200 , comprising the battery cell 100 in the above embodiment.

[0160] According to some embodiments of the present application, the present application further provides an electrical device 300 , comprising the battery 200 in the above embodiment.

[0161] According to some embodiments of the present application, as shown in FIG21 , the present application provides a battery cell 100, which includes an outer shell 20 and an electrode assembly 10. The outer shell 20 includes a shell body 23 and an end cover 24, the shell body 23 and the end cover 24 are connected, and the shell body 23 and the end cover 24 together define an installation cavity. The electrode assembly 10 is installed in the installation cavity. The bottom wall of the shell body 23 is constructed as a first wall portion 21, and a pressure relief portion 30 is provided on the bottom wall of the shell body 23. The pressure relief portion 30 is formed with a notch groove 31, and the bottom of the notch groove 31 is formed with a connected cracking section 32 and an extension section 33. The pressure relief portion 30 is configured so that when the internal pressure or temperature of the outer shell 20 reaches a threshold value, the cracking section 32 cracks before the extension section 33.

[0162] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0163] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0164] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and intent of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A battery cell, wherein: include: electrode assembly; a housing for accommodating the electrode assembly, the housing comprising a first wall portion; A pressure relief portion is provided on the first wall portion, the pressure relief portion is formed with a notched groove, the bottom of the notched groove is formed with a connected cracking section and an extension section, and the pressure relief portion is configured so that when the internal pressure or temperature of the shell reaches a threshold value, the cracking section cracks before the extension section.

2. The battery cell according to claim 1, wherein: A main body section is also formed at the bottom of the notch groove, the extension section is connected between the crack initiation section and the main body section, the thickness of the extension section is smaller than the thickness of the crack initiation section, and the thickness of the crack initiation section is smaller than the thickness of the main body section.

3. The battery cell according to claim 1 or 2, wherein: The ratio of the thickness of the crack initiation section to the thickness of the extension section is greater than or equal to 1.05 and less than or equal to 2.

1.

4. The battery cell according to any one of claims 1 to 3, wherein: The thickness of the crack initiation section is greater than or equal to 0.05 mm and less than or equal to 0.31 mm.

5. The battery cell according to any one of claims 1 to 4, wherein: The notched groove is an annular structure, and the inner edge of the notched groove defines a pressure relief area. The battery cell according to claim 5 , wherein: The pressure relief zone is in the shape of an elongated strip, and the ratio of the maximum length of the pressure relief zone to the maximum width of the pressure relief zone is greater than 1.2 and less than 5.

5.

7. The battery cell according to any one of claims 1 to 6, wherein: The scoring groove includes two first straight groove segments and two first arc-shaped groove segments. The two ends of each first straight groove segment are respectively connected to the two first arc-shaped groove segments to form the scoring groove into a ring shape. The length of the first straight groove segment is greater than the length of the first arc-shaped groove segment. The bottom of at least one first straight groove segment is formed with the crack initiation segment, and the bottom of at least one first arc-shaped groove segment is formed with the extension segment.

8. The battery cell according to any one of claims 1 to 6, wherein: The scoring groove includes two second straight groove segments and two third straight groove segments. The two ends of each second straight groove segment are respectively connected to the two third straight groove segments to form the scoring groove into a ring shape. The length of the second straight groove segment is greater than the length of the third straight groove segment. The bottom of at least one second straight groove segment is formed with the crack initiation segment, and the bottom of at least one third straight groove segment is formed with the extension segment.

9. The battery cell according to claim 8, wherein: The scoring groove further includes a second arcuate groove segment, and the second straight groove segment is connected to the third straight groove segment through the second arcuate groove segment.

10. The battery cell according to claim 9, wherein: The second arc-shaped groove segment is configured as an arc, and the chamfer radius of the second arc-shaped groove segment is greater than or equal to 1 mm.

11. The battery cell according to any one of claims 1 to 6, wherein: The crack initiation segment is a straight line segment extending along the first direction; or The crack initiation segment is a straight line segment extending along a second direction, and the second direction is perpendicular to the first direction.

12. The battery cell according to any one of claims 1 to 6, wherein: The pressure relief portion is integrally formed with the first wall portion; or, The pressure relief portion is separately provided with the first wall portion. The first wall portion is provided with a through hole, and the pressure relief portion is installed in the through hole.

13. The battery cell according to any one of claims 1 to 6, wherein: The housing includes a shell and an end cover. At least one side of the shell has an opening. The end cover is connected to the shell and is used to close the opening. The first wall portion is formed on the shell.

14. The battery cell according to claim 13, wherein: Two opposite sides of the shell are each provided with an opening, and the two end covers are used to close the openings on the corresponding sides.

15. The battery cell according to claim 13 or 14, wherein: The first wall portion is used to support the electrode assembly and is located below the electrode assembly.

16. The battery cell according to any one of claims 1 to 6, wherein: The housing includes a shell and an end cover. At least one side of the shell has an opening. The end cover is connected to the shell and is used to close the opening. The first wall portion is formed on the end cover.

17. A battery, wherein: The invention comprises a battery cell according to any one of claims 1 to 16.

18. An electrical device, wherein: Comprising a battery according to claim 17.

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