Battery cell, battery, and electric device

Abstract

The application discloses a battery monomer, a battery and a power utilization device. The battery monomer comprises an electrode assembly, a shell for accommodating the electrode assembly, and a pressure relief part. The shell comprises a first wall part. The pressure relief part is arranged on the first wall part and is formed with a notch groove. The bottom of the notch groove is formed with a connected crack initiation section and an extension section. The pressure relief part is configured to crack the crack initiation section first and then the extension section when the internal pressure or temperature of the shell reaches a threshold value. Thus, by arranging the crack initiation section and the extension section, when the internal pressure or temperature of the shell reaches the threshold value, the crack initiation section cracks first, then the extension section cracks, the difficulty of turning over of the pressure relief part is reduced, the battery monomer can be timely relieved, the explosion risk of the battery monomer is reduced, and the use safety of the battery monomer is improved.

Description

Technical Field

[0001] This application relates to the field of batteries, and in particular to a battery cell, a battery, and an electrical device. Background Technology

[0002] In related technologies, a battery cell includes a casing and an electrode assembly. The electrode assembly is located inside the casing, and the casing is provided with a pressure relief section. When the battery cell expands, the pressure relief section may crack and prevent normal rotation, causing the battery cell to fail to release pressure in time. This can lead to the end cap of the battery cell bursting open, reducing the safety of the battery cell in use. Summary of the Invention

[0003] This application aims to at least solve one of the technical problems existing in the prior art. To this end, one objective of this application is to propose a battery cell in which, when the internal pressure or temperature of the casing reaches a threshold, the initiation section cracks first, followed by the extension section, reducing the difficulty of flipping the pressure relief section. This allows the battery cell to release pressure in a timely manner, reducing the risk of battery cell explosion and improving the safety of battery cell use.

[0004] This application further proposes a battery.

[0005] This application further proposes an electrical device.

[0006] In a first aspect, embodiments of this application provide a single battery cell, comprising:

[0007] Electrode assembly;

[0008] A housing for accommodating an electrode assembly, the housing including a first wall portion;

[0009] The pressure relief section is located in the first wall portion. The pressure relief section has a groove, and the bottom of the groove has a connected crack initiation section and an extension section. The pressure relief section is configured such that when the internal pressure or temperature of the shell reaches a threshold, the crack initiation section cracks before the extension section.

[0010] In the above technical solution, by setting a crack initiation section and an extension section, when the internal pressure or temperature of the casing reaches the threshold, the crack initiation section cracks first, and then the extension section cracks. This reduces the difficulty of flipping the pressure relief section, allows the battery cell to be depressurized in time, reduces the risk of battery cell explosion, and improves the safety of battery cell use.

[0011] In some embodiments, a main body segment is also formed at the bottom of the groove, and an extension segment is connected between the crack initiation segment and the main body segment. The thickness of the extension segment is less than the thickness of the crack initiation segment, and the thickness of the crack initiation segment is less than the thickness of the main body segment.

[0012] In the above technical solution, by making the thickness of the extension section smaller than that of the initiating section, the initiating section can be made to crack before the extension section. Furthermore, after the initiating section cracks, the internal pressure of the outer casing facilitates the cracking of the extension section, which in turn promotes the outward rotation of the pressure relief section. This allows for timely pressure relief of the battery cell, further reducing the risk of battery cell explosion and improving battery cell safety. Because the thickness of the initiating section is smaller than that of the main body section, the main body section has the greatest structural strength. After the initiating and extension sections crack, the risk of the main body section cracking is reduced, thus reducing the risk of the pressure relief section structure flying out under the internal pressure of the outer casing. This reduces the risk of the pressure relief section structure flying out and damaging objects or injuring people, further improving battery cell safety.

[0013] In some embodiments, the ratio of the thickness of the initiation segment to the thickness of the extension segment is greater than or equal to 1.05 and less than or equal to 2.1.

[0014] In the above technical solution, by having a ratio of the thickness of the initiating section to the thickness of the extension section greater than or equal to 1.05 and less than or equal to 2.1, the extension section is beneficial to assist the bottom of the groove in cracking, reducing the occurrence of only the initiating section cracking after the pressure relief section is opened, reducing the occurrence of battery cell explosion, and also reducing the risk of the extension section cracking under normal operating conditions, and reducing the risk of battery cell leakage.

[0015] In some embodiments, the thickness of the initiation segment is greater than or equal to 0.05 mm and less than or equal to 0.31 mm.

[0016] In the above technical solution, by making the thickness of the crack initiation segment greater than or equal to 0.05 mm and less than or equal to 0.31 mm, the thickness of the crack initiation segment can be made appropriate, reducing the risk of cracking due to mechanical damage under long-term application conditions. Furthermore, when the internal pressure or temperature of the casing reaches the threshold, it is beneficial for the crack initiation segment to crack in time, which can allow the battery cells to release pressure in time.

[0017] In some embodiments, the groove is annular, and the inner edge of the groove defines a pressure relief area.

[0018] In the above technical solution, by setting the groove as a ring structure, the inner edge of the groove defines the pressure relief area. After the cracked section cracks, the extended section cracks under the internal pressure of the shell, which is more conducive to the pressure relief area of ​​the pressure relief part flipping outward, so that the pressure relief part forms an opening. This allows the battery cell to release pressure from the opening in time, further reducing the risk of battery cell explosion and further improving the safety of battery cell use.

[0019] In some embodiments, the pressure relief area is elongated, and the ratio of the maximum length of the pressure relief area to the maximum width of the pressure relief area is greater than 1.2 and less than 5.5.

[0020] In the above technical solution, by making the ratio of the maximum length of the pressure relief zone to the maximum width of the pressure relief zone greater than 1.2 and less than 5.5, it is beneficial to make the strain distribution of the pressure relief zone uniform under pressure drive. Under long-term use conditions, it reduces the risk of abnormal cracking of the pressure relief part. In addition, it is also beneficial to make the strain distribution of the groove different at different positions. When the internal pressure or temperature of the shell reaches the threshold, it is beneficial to make the crack initiation section crack before the extension section, thereby facilitating the normal cracking and pressure relief of the groove at the bottom of the groove and improving the working reliability of the pressure relief part.

[0021] In some embodiments, the scoring groove includes two first straight groove segments and two first arcuate groove segments. The two ends of each first straight groove segment are respectively connected to the two first arcuate groove segments to make the scoring groove structure annular. The length of the first straight groove segment is greater than the length of the first arcuate groove segment. At least one first straight groove segment has a crack initiation segment at its bottom and at least one first arcuate groove segment has an extension segment at its bottom.

[0022] In the above technical solution, the scoring groove includes two first straight groove segments and two first arc-shaped groove segments. When the internal pressure or temperature of the shell reaches a threshold, the crack initiation segment cracks first, tearing the bottom wall of the first straight groove segment. After the crack initiation segment cracks, it cracks along the extension segment at the first arc-shaped groove segment. Due to the high internal pressure of the shell, the pressure relief area is more conducive to turning outward under the action of the internal pressure of the shell, which can release the pressure of the battery cell in time, reduce the risk of battery cell explosion, and improve the safety of battery cell use.

[0023] In some embodiments, 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 so that the scoring groove is constructed as a ring. The length of the second straight groove segment is greater than the length of the third straight groove segment. At least one second straight groove segment has a crack initiation segment at its bottom, and at least one third straight groove segment has an extension segment at its bottom.

[0024] In the above technical solution, the groove includes two second straight groove segments and two third straight groove segments. When the internal pressure or temperature of the shell reaches the threshold, the crack initiation segment cracks first, tearing the bottom wall of the second straight groove segment. After the crack initiation segment cracks, it cracks along the extension segment at the third straight groove segment. Due to the high internal pressure of the shell, the pressure relief area is more conducive to turning outward under the action of the internal pressure of the shell, which can release the pressure of the battery cell in time, reduce the risk of battery cell explosion, and improve the safety of battery cell use.

[0025] In some embodiments, the groove further includes a second arc-shaped groove segment, and the second straight groove segment is connected to the third straight groove segment through the second arc-shaped groove segment.

[0026] In the above technical solution, by connecting the second arc-shaped groove segment between the second straight groove segment and the third straight groove segment, the connection between the second straight groove segment and the connected third straight groove segment can be smoothly transitioned, reducing the risk of premature cracking of the pressure relief section due to stress concentration. Furthermore, when the internal pressure or temperature of the casing reaches the threshold, after the cracking segment cracks, it is easy for the cracking segment to extend to the extension segment, further reducing the difficulty of flipping the pressure relief area, allowing the battery cell to be depressurized in a timely manner, further reducing the risk of battery cell explosion, and further improving the safety of battery cell use.

[0027] In some embodiments, the second arc-shaped groove segment is constructed as an arc, and the chamfer radius of the second arc-shaped groove segment is greater than or equal to 1 mm.

[0028] In the above technical solution, by setting the chamfer radius of the second arc-shaped groove segment to be greater than or equal to 1mm, the connection between the second straight groove segment and the connected third straight groove segment can be made smoother, further reducing the risk of premature cracking of the pressure relief section due to stress concentration. Furthermore, when the internal pressure or temperature of the casing reaches the threshold, after the cracking segment cracks, it is easier for the cracking segment to extend to the extension segment, further reducing the difficulty of flipping the pressure relief area. This allows the battery cell to be depressurized in a timely manner, further reducing the risk of battery cell explosion and further improving the safety of battery cell use.

[0029] In some embodiments, the crack initiation segment is a straight segment extending along a first direction; or

[0030] The crack initiation segment is a straight segment extending along a second direction, which is perpendicular to the first direction.

[0031] In the above technical solution, by setting the crack initiation segment as a straight segment extending along the first direction, it is beneficial for the crack initiation segment to preferentially extend and initiate cracking. By setting the crack initiation segment as a straight segment extending along the second direction, the force on the crack initiation segment can be greater than that on the extension segment, which is more conducive to the crack initiation segment to preferentially extend and initiate cracking, allowing the battery cell to release pressure in a timely manner and further reducing the risk of battery cell explosion.

[0032] In some embodiments, the pressure relief portion is integrally formed with the first wall portion; or...

[0033] The pressure relief part and the first wall part are separately provided. The first wall part is provided with a through hole, and the pressure relief part is installed in the through hole.

[0034] In the above technical solution, by integrally molding the pressure relief part and the first wall part, the molding method of the pressure relief part is simple, which can reduce the number of components that make up the battery cell, simplify the structure of the battery cell, and reduce the manufacturing cost of the battery cell. By constructing the pressure relief part and the first wall part as separate parts, it is easy to set the pressure relief part on the outer shell, which is easy to manufacture and efficient, thereby improving the production efficiency of the battery cell.

[0035] In some embodiments, the housing includes a housing and an end cap, the housing having an opening on at least one side, the end cap being connected to the housing and used to close the opening, and a first wall portion being formed in the housing.

[0036] In the above technical solution, by forming the first wall portion on the housing, the structure of the end cap can be simplified, and the distance between the pressure relief portion and the main body of the electrode assembly can be shortened. This shortens the path of the discharge medium to the pressure relief portion during pressure relief, reduces the time for the discharge medium to reach the pressure relief portion, improves the timeliness of pressure relief of the battery cell, and thus effectively improves the reliability of the battery cell.

[0037] In some embodiments, the housing has openings on opposite sides, and two end caps are used to close the openings on the corresponding sides.

[0038] In the above technical solution, the shell has openings on both sides, and two end caps are used to close the openings on the corresponding sides, which together define the mounting cavity. This facilitates the manufacturing and shaping of the shell, and also facilitates the electrode assembly to lead out the tabs from both ends, thereby facilitating the separate arrangement of the two electrical connection terminals and reducing the risk of short circuits in the battery cells.

[0039] In some embodiments, the first wall portion is used to support the electrode assembly and is located below the electrode assembly.

[0040] In the above technical solution, the electrode assembly can be stably installed in the mounting cavity of the housing by supporting the electrode assembly through the first wall portion.

[0041] In some embodiments, the housing includes a housing and an end cap, the housing having an opening on at least one side, the end cap being connected to the housing and used to close the opening, and a first wall portion being formed in the end cap.

[0042] In the above technical solution, by setting the pressure relief part on the end cover, the structure of the shell can be simplified and the production efficiency of the shell can be improved.

[0043] Secondly, embodiments of this application also provide a battery, including the aforementioned battery cell.

[0044] Thirdly, embodiments of this application also provide an electrical device, including the battery described above.

[0045] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0046] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0047] Figure 1This is a schematic diagram of an electrical device according to an embodiment of this application;

[0048] Figure 2 This is a schematic diagram of a battery according to an embodiment of this application;

[0049] Figure 3 This is a schematic diagram of the pressure relief section of a battery cell located on the end cap according to an embodiment of this application;

[0050] Figure 4 This is an exploded view of a battery cell according to an embodiment of this application;

[0051] Figure 5 This is a schematic diagram of the pressure relief section according to the first embodiment of this application;

[0052] Figure 6 This is a front view of the pressure relief section according to the first embodiment of this application;

[0053] Figure 7 yes Figure 6 Sectional view at point AA;

[0054] Figure 8 yes Figure 7 Enlarged view at point C;

[0055] Figure 9 yes Figure 6 Sectional view at point BB;

[0056] Figure 10 yes Figure 9 Enlarged view at point D;

[0057] Figure 11 yes Figure 9 Enlarged view at point E in the middle;

[0058] Figure 12 This is a schematic diagram of the pressure relief section according to the second embodiment of this application;

[0059] Figure 13 This is a front view of the pressure relief section according to the second embodiment of this application;

[0060] Figure 14 This is a schematic diagram of the pressure relief section according to the third embodiment of this application;

[0061] Figure 15 This is a front view of the pressure relief section according to the third embodiment of this application;

[0062] Figure 16 This is a schematic diagram showing the trapezoidal cross-section of the groove in the pressure relief section according to an embodiment of this application;

[0063] Figure 17 This is a schematic diagram showing that the cross-section of the groove in the pressure relief part according to an embodiment of this application is semi-circular;

[0064] Figure 18 This is a schematic diagram showing the triangular cross-section of the groove in the pressure relief section according to an embodiment of this application;

[0065] Figure 19 This is a schematic diagram showing that the cross-section of the groove in the pressure relief part according to an embodiment of this application is an elongated oval.

[0066] Figure 20 This is a schematic diagram showing that grooves are formed on both sides of the pressure relief part according to an embodiment of this application;

[0067] Figure 21 This is a schematic diagram of the pressure relief section of a battery cell located on the outer casing according to an embodiment of this application.

[0068] Figure label:

[0069] 100 for a single battery cell;

[0070] Electrode assembly 10;

[0071] 20; first wall portion 21; second wall portion 22; housing 23; end cap 24; electrical connection terminal 25;

[0072] Pressure relief section 30; scoring groove 31; crack initiation section 32; extension section 33; main body section 34; pressure relief zone 35; first straight groove section 36; first arc-shaped groove section 37; second straight groove section 38; third straight groove section 39; second arc-shaped groove section 391;

[0073] Battery 200; Box 201; First Box Body 202; Second Box Body 203;

[0074] Electrical device 300; controller 400; motor 500. Detailed Implementation

[0075] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0076] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0077] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0078] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0079] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0080] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0081] In this application, "multiple" means two or more (including two).

[0082] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0083] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0084] The battery mentioned in the embodiments of this application refers to a single physical module comprising 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, parallel, or mixed via a busbar.

[0085] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0086] In some embodiments, the battery can be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0087] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0088] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0089] The development of battery technology must take into account multiple design factors, such as energy density, cycle life, discharge capacity, charge / discharge rate, and other performance parameters. In addition, battery safety performance also needs to be considered.

[0090] To ensure the safety of individual battery cells, pressure relief sections can be installed on the cell casing. In the event of thermal runaway, these sections release internal pressure, improving the cell's safety. However, during pressure relief, if the pressure relief section cracks and cannot be properly rotated, the cell may not release pressure in time, causing the end cap to burst open and reducing its safety during use.

[0091] In view of this, this application provides a battery cell including an electrode assembly and a housing. The housing is used to accommodate the electrode assembly and includes a first wall portion. A pressure relief portion is disposed on the first wall portion. The pressure relief portion has a groove formed therein. A connected crack initiation section and an extension section are formed at the bottom of the groove. The pressure relief portion is configured such that when the internal pressure or temperature of the housing reaches a threshold, the crack initiation section cracks before the extension section, and then the extension section cracks. This reduces the difficulty of flipping the pressure relief portion, facilitates the flipping of the pressure relief portion, allows the battery cell to release pressure in a timely manner, reduces the risk of the battery cell end cap bursting, and improves the safety of the battery cell in use.

[0092] The technical solutions described in the embodiments of this application are applicable to batteries and electrical devices that use batteries.

[0093] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0094] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0095] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle provided in some embodiments of this application. A battery 200 is disposed inside the vehicle, and the battery 200 may be located at the bottom, front, or rear of the vehicle. The battery 200 can be used to power the vehicle; for example, the battery 200 can serve as the vehicle's operating power source.

[0096] The vehicle may also include a controller 400 and a motor 500. The controller 400 controls the battery 200 to supply power to the motor 500, for example, for the power needs of the vehicle during starting, navigation and driving.

[0097] In some embodiments of this application, the battery 200 can not only serve as the operating power source for the vehicle, but also as the driving power source for the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0098] Please refer to Figure 2 , Figure 2 This is an exploded view of a battery 200 provided for some embodiments of this application. The battery 200 includes a battery cell 100 and a housing 201 for housing the battery cell 100.

[0099] The housing 201 is a component that houses the battery cell 100, providing a placement space for the battery cell 100. The housing 201 can adopt various structures. In some embodiments, the housing 201 may include a first housing body 202 and a second housing body 203, which overlap each other to define a placement space for accommodating the battery cell 100. The first housing body 202 and the second housing body 203 can be various shapes, such as cuboids, cylinders, etc. The first housing body 202 can be a hollow structure open on one side, and the second housing body 203 can also be a hollow structure open on one side, with the open side of the second housing body 203 overlapping the open side of the first housing body 202, thus forming a housing 201 with a placement space. Alternatively, the first housing body 202 can be a hollow structure open on one side, and the second housing body 203 can be a plate-like structure, with the second housing body 203 overlapping the open side of the first housing body 202, thus forming a housing 201 with a placement space. As an example, the battery cell 100 can be a cylindrical battery cell 100, a prismatic battery cell 100, a pouch battery cell 100, or a battery cell 100 of other shapes. The prismatic battery cell 100 includes a prismatic battery cell 100, a blade-shaped battery cell 100, and a multi-prismatic battery 200, such as a hexagonal prismatic battery 200. There are no particular limitations in this application.

[0100] In battery 200, there can be one or more battery cells 100. If there are multiple battery cells 100, they can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 100 are connected in both series and parallel. Alternatively, multiple battery cells 100 can be first connected in series, parallel, or in a mixed configuration to form a battery module 200, and then these modules can be connected in series, parallel, or in a mixed configuration to form a whole, which is then housed within the housing 201. Another option is that all battery cells 100 can be directly connected in series, parallel, or in a mixed configuration, and then the whole assembly of all battery cells 100 is housed within the housing 201.

[0101] Please refer to Figure 3 and Figure 4 , Figure 3 A schematic diagram of a battery cell 100 provided in some embodiments of this application; Figure 4 This is an exploded view of a battery cell 100 provided in some embodiments of this application. The battery cell 100 may include a housing 20 and an electrode assembly 10.

[0102] The housing 20 is used to house the electrode assembly 10 and electrolyte components. The housing 20 can be a steel housing, an aluminum housing, a plastic housing (such as a polypropylene housing), a composite metal housing (such as a copper-aluminum composite housing 20), or an aluminum-plastic film, etc. As an example, the housing 20 may include a housing 23 and an end cap 24.

[0103] The shell 23 can be a hollow structure with an opening at one end, or it can be a hollow structure with openings at both opposite ends. The shell 23 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0104] End cap 24 is a component that closes the opening of housing 23 to isolate the internal environment of battery cell 100 from the external environment. End cap 24 and housing 23 together define a space for accommodating electrode assembly 10, electrolyte, and other components. End cap 24 can be connected to housing 23 by welding or roll sealing to close the opening of housing 23. The shape of end cap 24 can be adapted to the shape of housing 20; for example, if housing 23 is a cuboid structure, end cap 24 can be a rectangular plate structure adapted to housing 23. End cap 24 can also be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy.

[0105] In the battery cell 100, there can be one or two end caps 24. In an embodiment where the housing 23 is a hollow structure with openings at both ends, two end caps 24 can be provided, each closing one of the two openings of the housing 23, and the two end caps 24 and the housing 23 together define the accommodating space. In an embodiment where the housing 23 is a hollow structure with an opening at one end, one end cap 24 can be provided, closing one opening of the housing 23, and the one end cap 24 and the housing 23 together define the accommodating space.

[0106] The electrode assembly 10 includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of the battery cell 100, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator is disposed between the positive and negative electrodes to prevent short circuits between them while allowing active ions to pass through.

[0107] In some embodiments, the positive electrode can be a positive electrode sheet, which may include a positive current collector and a positive active material region disposed on at least one surface of the positive current collector, the positive active material region having a positive active material.

[0108] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material region is disposed on either or both of the two opposite surfaces of the positive current collector.

[0109] 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.

[0110] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material region is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0111] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0112] In some embodiments, the electrode assembly 10 further includes an isolator disposed between the positive and negative electrodes.

[0113] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0114] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0115] In some embodiments, the battery cell 100 also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0116] In some embodiments, the electrode assembly 10 has a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0117] In some embodiments, the electrode assembly 10 has a stacked structure.

[0118] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0119] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0120] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0121] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0122] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0123] In some embodiments, the electrode assembly 10 may be flat or polygonal in shape.

[0124] In some embodiments, the electrode assembly 10 is provided with tabs that can conduct current from the electrode assembly 10. The tabs include a positive tab and a negative tab.

[0125] 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 used for electrical connection with the tabs of the electrode assembly 10 to output electrical energy from the battery cell 100. The electrical connection terminal 25 and the tabs may be directly connected, for example, by direct welding. The electrical connection terminal 25 and the tabs may also be indirectly connected, for example, by indirect connection through a current collector. The current collector may be a metallic conductor, such as copper, iron, aluminum, steel, or aluminum alloy.

[0126] like Figure 3 As shown, taking the shell 23 as an example of a hollow structure with an opening at one end, two electrical connection terminals 25 can be provided on the end cover 24. The two electrical connection terminals 25 are a positive electrical connection terminal 25 (i.e., a positive terminal) and a negative electrical connection terminal 25 (i.e., a negative terminal). The positive electrical connection terminal 25 is electrically connected to the positive terminal lug, and the negative electrical connection terminal 25 is electrically connected to the negative terminal lug.

[0127] The following is for reference. Figures 5-21 A battery cell 100 according to an embodiment of this application is described.

[0128] According to an embodiment of this application, a battery cell 100 includes: an electrode assembly 10; a housing 20 for accommodating the electrode assembly 10, the housing 20 including a first wall portion 21; and a pressure relief portion 30 disposed on the first wall portion 21. The pressure relief portion 30 has a scoring groove 31, and the bottom of the scoring groove 31 has a connected crack initiation section 32 and an extension section 33. The pressure relief portion 30 is configured such that when the internal pressure or temperature of the housing 20 reaches a threshold, the crack initiation section 32 cracks before the extension section 33.

[0129] The electrode assembly 10 includes a positive electrode and a negative electrode. For example, the electrode assembly 10 includes at least one positive electrode and at least one negative electrode. The at least one positive electrode and at least one negative electrode are stacked to form the electrode assembly 10. At least a portion of the positive electrode and at least a portion of the negative electrode can be stacked along a first direction. When the battery cell 100 is in... Figure 3 When placed in the indicated direction, the first direction refers to... Figure 3 in the Y direction.

[0130] The electrode assembly 10 can also be a wound type. The positive electrode and negative electrode of the electrode assembly 10 are wound into shape after being superimposed with the separator. The positive electrode portion and the negative electrode portion are stacked along the first direction.

[0131] The housing 20 defines a mounting cavity, in which the electrode assembly 10 of the battery cell 100 is mounted. The housing 20 includes a first wall portion 21, which is the cavity wall of the mounting cavity.

[0132] A pressure relief section 30 is located on the first wall portion 21. The pressure relief section 30 can be an explosion-proof valve, or the first wall portion 21 can have a grooved structure to form the pressure relief section 30. The pressure relief section 30 has a grooved groove 31, and the bottom of the grooved groove 31 has a connected crack initiation section 32 and an extension section 33. In other words, the bottom wall of the grooved groove 31 has a connected crack initiation section 32 and an extension section 33. When the internal pressure or temperature of the casing 20 reaches a threshold, the crack initiation section 32 cracks before the extension section 33, i.e., the crack initiation section 32 cracks before the extension section 33. When the internal pressure or temperature of the mounting cavity reaches a certain threshold, the grooved groove 31 of the pressure relief section 30 opens, and the gas and substances inside the battery cell 100 are discharged from the pressure relief section 30, achieving a pressure relief effect. This threshold design varies depending on the design requirements and may depend on one or more materials among the positive electrode, negative electrode, electrolyte, and separator in the battery cell 100.

[0133] When the internal pressure or temperature of the outer casing 20 reaches a threshold, the crack initiation section 32 cracks first, tearing the bottom wall of the groove 31. After the crack initiation section 32 cracks, it cracks along the extension section 33, that is, the bottom wall of the groove 31 cracks along the extension section 33. Due to the large internal pressure of the outer casing 20, under the action of the internal pressure of the outer casing 20, it is beneficial for part of the structure of the pressure relief section 30 to flip outward, which can release the pressure of the battery cell 100 in time, reduce the risk of battery cell 100 explosion, and improve the safety of battery cell 100 in use.

[0134] In the above technical solution, by setting the crack initiation section 32 and the extension section 33, when the internal pressure or temperature of the outer casing 20 reaches the threshold, the crack initiation section 32 cracks first, and then the extension section 33 cracks, which reduces the difficulty of flipping the pressure relief section 30, allows the battery cell 100 to release pressure in time, reduces the risk of battery cell 100 explosion, and improves the safety of battery cell 100 in use.

[0135] According to some embodiments of this application, such as Figure 5 , Figure 12 and Figure 14 As shown, a main body segment 34 is also formed at the bottom of the groove 31, and an extension segment 33 is connected between the crack initiation segment 32 and the main body segment 34. The thickness of the extension segment 33 is less than the thickness of the crack initiation segment 32, and the thickness of the crack initiation segment 32 is less than the thickness of the main body segment 34.

[0136] The bottom of the groove 31 also forms a main body segment 34; in other words, the bottom wall of the groove 31 also forms a main body segment 34. An extension segment 33 connects the crack initiation segment 32 and the main body segment 34. As an example, one end of the crack initiation segment 32 is connected to one end of the extension segment 33, one end of the main body segment 34 is connected to the other end of the extension segment 33, and the other end of the crack initiation segment 32 is connected to the other end of the main body segment 34. As another example, there are two extension segments 33: one extension segment 33 connects one end of the crack initiation segment 32 and one end of the main body segment 34, and the other extension segment 33 connects the other end of the crack initiation segment 32 and the other end of the main body segment 34. The thickness of the extension segment 33 is smaller than that of the crack initiation segment 32, which in turn is smaller than that of the main body segment 34. By making the thickness of the extension segment 33 smaller than that of the crack initiation segment 32, the crack initiation segment 32 can crack before the extension segment 33. Furthermore, after the crack initiation segment 32 cracks, the extension segment 33 is more likely to crack under the internal pressure of the outer casing 20. This facilitates the outward flipping of part of the pressure relief section 30, allowing the battery cell 100 to release pressure in a timely manner, further reducing the risk of battery cell 100 explosion and improving the safety of battery cell 100. Because the thickness of the crack initiation segment 32 is smaller than that of the main body segment 34, the main body segment 34 has the greatest structural strength. After the crack initiation segment 32 and the extension segment 33 crack, the risk of the main body segment 34 cracking is reduced, thereby reducing the risk of the pressure relief section 30 structure flying out under the internal pressure of the outer casing 20. This reduces the risk of the pressure relief section 30 structure flying out and damaging objects or injuring people, further improving the safety of battery cell 100.

[0137] It should be noted that the extension segment 33, the crack initiation segment 32, and the main body segment 34 can all be set to a uniform thickness, or the extension segment 33, the crack initiation segment 32, and the main body segment 34 can all be set to a non-uniform thickness, or a portion of the extension segment 33, the crack initiation segment 32, and the main body segment 34 can be set to a uniform thickness, while another portion of the extension segment 33, the crack initiation segment 32, and the main body segment 34 can be set to a non-uniform thickness. This application uses the example of setting the extension segment 33 to a non-uniform thickness and the crack initiation segment 32 to a uniform thickness for illustration. The thickness of the extension segment 33 is the average thickness of the extension segment 33, and the thickness values ​​of each region of the crack initiation segment 32 are equal.

[0138] In the above technical solution, by making the thickness of the extension segment 33 smaller than that of the crack initiation segment 32, the crack initiation segment 32 can crack before the extension segment 33. Furthermore, after the crack initiation segment 32 cracks, the extension segment 33 is more likely to crack under the internal pressure of the outer casing 20. This facilitates the outward flipping of part of the pressure relief section 30, allowing the battery cell 100 to release pressure in a timely manner, further reducing the risk of explosion and improving the safety of the battery cell 100. Because the thickness of the crack initiation segment 32 is smaller than that of the main body segment 34, the main body segment 34 has the greatest structural strength. After the crack initiation segment 32 and the extension segment 33 crack, the risk of the main body segment 34 cracking is reduced, thereby reducing the risk of the pressure relief section 30 structure flying out under the internal pressure of the outer casing 20. This reduces the risk of the pressure relief section 30 structure flying out and damaging objects or injuring people, further improving the safety of the battery cell 100.

[0139] According to some embodiments of this application, the ratio of the thickness of the 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.

[0140] The ratio of the thickness of the initiating section 32 to the thickness of the extension section 33 affects the functionality of the pressure relief section 30. When the ratio is too small, i.e., the thicknesses of the initiating section 32 and the extension section 33 are designed to be similar, it is not conducive to the extension section 33 assisting the bottom of the groove 31 in cracking. This can easily lead to only the initiating section 32 cracking after the pressure relief section 30 is opened, resulting in the battery cell 100 bursting due to insufficient pressure relief area. Therefore, the ratio of the thickness of the initiating section 32 to the thickness of the extension section 33 has a minimum value. When the ratio is too large, the extension section 33 is prone to non-pneumatic mechanical damage, i.e., cracking, under normal operating conditions (vibration, shock, and respiratory fatigue), due to its insufficient thickness. This can lead to abnormal leakage of the battery cell 100. Therefore, the ratio of the thickness of the initiating section 32 to the thickness of the extension section 33 has a maximum value.

[0141] In this application, the ratio of the thickness of the initiating 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 initiating 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 the bottom of the groove 31 in cracking, reduce the occurrence of only the initiating section 32 cracking after the pressure relief section 30 is opened, reduce the occurrence of battery cell 100 explosion, and also reduce the risk of the extension section 33 cracking under normal operating conditions, and reduce the risk of battery cell 100 leakage.

[0142] In the above technical solution, by having the ratio of the thickness of the initiating section 32 to the thickness of the extension section 33 greater than or equal to 1.05 and less than or equal to 2.1, the extension section 33 is beneficial to assist the bottom of the groove 31 in cracking, reducing the occurrence of only the initiating section 32 cracking after the pressure relief section 30 is opened, reducing the occurrence of battery cell 100 explosion, and also reducing the risk of the extension section 33 cracking under normal operating conditions, and reducing the risk of battery cell 100 leakage.

[0143] According to some embodiments of this 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.

[0144] The thickness of the crack initiation segment 32 can be set to values ​​such as 0.05mm, 0.06mm, 0.1mm, 0.2mm, and 0.31mm. Any value between 0.05mm, 0.31mm, and 0.05mm-0.31mm is acceptable. If the thickness of the crack initiation segment 32 is less than 0.05mm, making it too thin, it is prone to cracking due to mechanical damage under long-term operating conditions. If the thickness of the crack initiation segment 32 is greater than 0.31mm, making it too thick, it may fail to crack in time when the internal pressure or temperature of the outer casing 20 reaches a threshold. Therefore, in this application, by having a thickness of 0.05 mm or more and 0.31 mm or less, the thickness of the initiation segment 32 is made suitable, reducing the risk of cracking due to mechanical damage under long-term application conditions. Furthermore, when the internal pressure or temperature of the casing 20 reaches a threshold, it is beneficial for the initiation segment 32 to crack in time, which can allow the battery cell 100 to release pressure in time.

[0145] In the above technical solution, by having a thickness of 0.05 mm or less than 0.31 mm, the thickness of the initiation segment 32 can be made suitable, reducing the risk of cracking due to mechanical damage under long-term application conditions. Furthermore, when the internal pressure or temperature of the outer casing 20 reaches the threshold, it is beneficial for the initiation segment 32 to crack in time, which can allow the battery cell 100 to release pressure in time.

[0146] According to some embodiments of this application, such as Figure 6 , Figure 13 and Figure 15 As shown, the groove 31 is an annular structure, and the inner edge of the groove 31 defines the pressure relief area 35.

[0147] The groove 31 is an annular structure. Along the width direction of the groove 31, the groove 31 has an outer edge and an inner edge. The inner edge of the groove 31 can define the pressure relief area 35. After the cracking section 32 cracks, under the internal pressure of the outer shell 20, the extension section 33 cracks, which makes it more conducive for the pressure relief area 35 of the pressure relief part 30 to flip outward, so that the pressure relief part 30 forms an opening. This allows the battery cell 100 to release pressure from the opening in time, further reducing the risk of battery cell 100 explosion and further improving the safety of battery cell 100 in use.

[0148] In the above technical solution, by setting the groove 31 as an annular structure, the inner edge of the groove 31 defines the pressure relief area 35. After the cracking section 32 cracks, under the internal pressure of the outer shell 20, the extension section 33 cracks, which makes it more conducive for the pressure relief area 35 of the pressure relief part 30 to flip outward, so that the pressure relief part 30 forms an opening. This allows the battery cell 100 to release pressure from the opening in time, further reducing the risk of battery cell 100 explosion and further improving the safety of battery cell 100 in use.

[0149] According to some embodiments of this application, such as Figure 6 , Figure 13 and Figure 15 As shown, the pressure relief zone 35 is elongated, 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.

[0150] Among them, the pressure relief zone 35 has a long strip structure, as an example, such as Figure 6 As shown, the pressure relief zone 35 has an elongated oval structure. As another example, such as... Figure 13 and Figure 15 As shown, the pressure relief zone 35 has a rectangular structure. Figure 6 Taking the elongated oval structure of the pressure relief zone 35 as an example, the maximum length of the pressure relief zone 35 along its length direction is L mm, and the maximum width of the pressure relief zone 35 along its width direction is W mm. The ratio of the maximum length to the maximum width of the pressure relief zone 35 is called the aspect ratio. This parameter characterizes the degree to which the shape of the explosion-proof valve deviates from a square / circle. The ratio of the maximum length to the maximum width of the pressure relief zone 35 should be greater than 1.2 and less than 5.5. The ratio of the maximum length 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 to the maximum width of the pressure relief zone 35 is between 1.2 and 5.5, quality inspection is acceptable.

[0151] It should be noted that when the ratio of the maximum length to the maximum width of the pressure relief zone 35 increases, the shape of the pressure relief zone 35 tends to be elongated, and the uneven strain distribution under pressure exacerbates. This can easily lead to abnormal cracking of the pressure relief section 30 under long-term use. Therefore, considering the long-term reliability design requirements of the pressure relief section 30, the ratio of the maximum length to the maximum width of the pressure relief zone 35 has a maximum design value. When the ratio of the maximum length to the maximum width of the pressure relief zone 35 decreases, the shape of the pressure relief zone 35 tends to be square or circular. The strain distribution of the grooves at different locations on the groove 31 becomes more uniform, increasing the strength. This is not conducive to normal cracking and pressure relief at the bottom of the groove 31, affecting the normal functionality of the pressure relief section 30. Therefore, the ratio of the maximum length to the maximum width of the pressure relief zone 35 has a minimum design value.

[0152] In this 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 to make the strain distribution of the pressure relief zone 35 uniform under pressure drive. Under long-term use conditions, it reduces the risk of abnormal cracking of the pressure relief section 30. In addition, it is also beneficial to make the strain distribution of the groove 31 different at different positions. When the internal pressure or temperature of the outer shell 20 reaches the threshold, it is beneficial to make the crack initiation section 32 crack before the extension section 33, thereby facilitating the normal cracking and pressure relief of the groove at the bottom of the groove 31 and improving the working reliability of the pressure relief section 30.

[0153] According to some embodiments of this application, such as Figure 5 and Figure 6 As shown, the scoring groove 31 includes two first straight groove segments 36 and two first arc-shaped groove segments 37. The two ends of each first straight groove segment 36 are respectively connected to the two first arc-shaped groove segments 37 so that the scoring groove 31 is constructed as a ring. The length of the first straight groove segment 36 is greater than the length of the first arc-shaped groove segment 37. At least one first straight groove segment 36 has a crack initiation segment 32 at its bottom, and at least one first arc-shaped groove segment 37 has an extension segment 33 at its bottom.

[0154] Among them, such as Figure 6As shown, the scoring groove 31 includes two first straight groove segments 36 and two first arc-shaped groove segments 37. The first straight groove segments 36 can be straight or similarly straight. The first arc-shaped groove segments 37 can be arc-shaped. The two first straight groove segments 36 are arranged opposite each other and spaced apart. The two first straight groove segments 36 can be parallel to each other, and the two first arc-shaped groove segments 37 are arranged opposite each other and spaced apart. Each end of the first straight groove segment 36 is connected to the two first arc-shaped groove segments 37 respectively. The two first straight groove segments 36 and the two first arc-shaped groove segments 37 form a closed ring structure, which can make the scoring groove 31 ring-shaped or elongated oval. The length of the first straight groove segment 36 is greater than the length of the first arc-shaped groove segment 37, thus making the pressure relief area 35 elongated. At least one of the first straight groove segments 36 has a crack initiation segment 32 formed at its bottom. That is, the bottom of one first straight groove segment 36 has a crack initiation segment 32, or both of the first straight groove segments 36 have crack initiation segments 32 formed at their bottoms. At least one first arcuate groove segment 37 has an extension segment 33 formed at its bottom; that is, one first arcuate groove segment 37 has an extension segment 33 formed at its bottom, or both first arcuate groove segments 37 have extension segments 33 formed at their bottoms. This application uses the example of one first straight groove segment 36 having a crack initiation segment 32 at its bottom and both first arcuate groove segments 37 having extension segments 33 at their bottoms for illustration. When one first straight groove segment 36 has a crack initiation segment 32 at its bottom, the other first straight groove segment 36 has a main body segment 34 at its bottom. As an example, the entire bottom region of one first straight groove segment 36 has a crack initiation segment 32, the entire bottom of the other first straight groove segment 36 has a main body segment 34, and the entire bottom of each first arcuate groove segment 37 has an extension segment 33.

[0155] When the internal pressure or temperature of the outer casing 20 reaches the threshold, the crack initiation section 32 cracks first, tearing the bottom wall of the first straight groove section 36. After the crack initiation section 32 cracks, it cracks along the extension section 33 at the first arc-shaped groove section 37. Due to the large internal pressure of the outer casing 20, the pressure relief area 35 is more likely to flip outward under the action of the internal pressure of the outer casing 20, which can release the pressure of the battery cell 100 in time, reduce the risk of battery cell 100 explosion, and improve the safety of battery cell 100 in use.

[0156] In the above technical solution, the groove 31 includes two first straight groove segments 36 and two first arc-shaped groove segments 37. When the internal pressure or temperature of the outer casing 20 reaches a threshold, the crack initiation segment 32 cracks first, tearing the bottom wall of the first straight groove segment 36. After the crack initiation segment 32 cracks, it cracks along the extension segment 33 at the first arc-shaped groove segment 37. Due to the large internal pressure of the outer casing 20, the pressure relief area 35 is more likely to flip outward under the action of the internal pressure of the outer casing 20, which can release the pressure of the battery cell 100 in time, reduce the risk of battery cell 100 explosion, and improve the safety of battery cell 100.

[0157] According to some embodiments of this application, such as Figure 12 As shown, the groove 31 includes two second straight groove segments 38 and two third straight groove segments 39. The two ends of each second straight groove segment 38 are respectively connected to the two third straight groove segments 39 so that the groove 31 is constructed as a ring. The length of the second straight groove segment 38 is greater than the length of the third straight groove segment 39. At least one second straight groove segment 38 has a crack initiation segment 32 at its bottom, and at least one third straight groove segment 39 has an extension segment 33 at its bottom.

[0158] The scoring groove 31 includes two second straight groove segments 38 and two third straight groove segments 39. The second straight groove segments 38 can be straight or similarly straight, and the third straight groove segments 39 can be straight or similarly straight. The two second straight groove segments 38 are arranged opposite to each other and spaced apart, and can be parallel to each other. The two third straight groove segments 39 are also arranged opposite to each other and spaced apart, and can be parallel to each other. Each second straight groove segment 38 is connected to one end of each of the two third straight groove segments 39. The two second straight groove segments 38 and the two third straight groove segments 39 form a closed annular structure, which can make the scoring groove 31 either annular or rectangular. The length of the second straight groove segment 38 is greater than the length of the third straight groove segment 39, thus making the pressure relief zone 35 elongated. At least one second straight groove segment 38 has a crack initiation section 32 at its bottom; that is, either one second straight groove segment 38 has a crack initiation section 32 at its bottom, or both second straight groove segments 38 have crack initiation sections 32 at their bottoms. At least one third straight groove segment 39 has an extension segment 33 formed at its bottom; that is, one third straight groove segment 39 has a crack initiation segment 32 formed at its bottom, or both third straight groove segments 39 have crack initiation segments 32 formed at their bottoms. This application uses the example of one second straight groove segment 38 having a crack initiation segment 32 at its bottom and both third straight groove segments 39 having extension segments 33 formed at their bottoms for illustration. When one second straight groove segment 38 has a crack initiation segment 32 at its bottom, the other second straight groove segment 38 has a main body segment 34 formed at its bottom. As an example, the entire bottom region of one second straight groove segment 38 has a crack initiation segment 32, the entire bottom of the other second straight groove segment 38 has a main body segment 34, and the entire bottom of each third straight groove segment 39 has an extension segment 33 formed.

[0159] When the internal pressure or temperature of the outer casing 20 reaches the threshold, the crack initiation section 32 cracks first, tearing the bottom wall of the second straight groove section 38. After the crack initiation section 32 cracks, it cracks along the extension section 33 at the third straight groove section 39. Due to the large internal pressure of the outer casing 20, the pressure relief area 35 is more likely to flip outward under the action of the internal pressure of the outer casing 20, which can release the pressure of the battery cell 100 in time, reduce the risk of battery cell 100 explosion, and improve the safety of battery cell 100 in use.

[0160] In the above technical solution, the 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 casing 20 reaches the threshold, the crack initiation segment 32 cracks first, tearing the bottom wall of the second straight groove segment 38. After the crack initiation segment 32 cracks, it cracks along the extension segment 33 at the third straight groove segment 39. Due to the large internal pressure of the outer casing 20, the pressure relief area 35 is more likely to flip outward under the action of the internal pressure of the outer casing 20, which can release the pressure of the battery cell 100 in time, reduce the risk of battery cell 100 explosion, and improve the safety of battery cell 100.

[0161] According to some embodiments of this application, such as Figure 14 and Figure 15 As shown, the groove 31 also includes a second arc-shaped groove segment 391, and the second straight groove segment 38 is connected to the third straight groove segment 39 through the second arc-shaped groove segment 391.

[0162] The bottom of the second arc-shaped groove segment 391 may have an extension segment 33. The second arc-shaped groove segment 391 may be circular. The second straight groove segment 38 is connected to the connected third straight groove segment 39 by the second arc-shaped groove segment 391. As an example, each second straight groove segment 38 is connected to the connected third straight groove segment 39 by the second arc-shaped groove segment 391, so that the second straight groove segment 38 is connected to the third straight groove segment 39 through the second arc-shaped groove segment 391. By connecting the second straight groove segment 391 between the second straight groove segment 38 and the third straight groove segment 39, the connection between the second straight groove segment 38 and the connected third straight groove segment 39 can be smoothly transitioned, reducing the risk of premature cracking of the pressure relief section 30 due to stress concentration. Furthermore, when the internal pressure or temperature of the outer casing 20 reaches the threshold, after the crack initiation segment 32 cracks, it is easy for the crack initiation segment 32 to extend the crack to the extension segment 33, further reducing the difficulty of flipping the pressure relief area 35. This allows the battery cell 100 to be depressurized in a timely manner, further reducing the risk of battery cell 100 explosion and further improving the safety of battery cell 100 in use.

[0163] In the above technical solution, the second arc-shaped groove segment 391 connects the second straight groove segment 38 and the third straight groove segment 39, which enables a smooth transition at the connection between the second straight groove segment 38 and the connected third straight groove segment 39, reducing the risk of premature cracking of the pressure relief section 30 due to stress concentration. Furthermore, when the internal pressure or temperature of the outer casing 20 reaches the threshold, after the crack initiation segment 32 cracks, it is easy for the crack initiation segment 32 to extend the crack to the extension segment 33, further reducing the difficulty of flipping the pressure relief area 35. This allows the battery cell 100 to be depressurized in a timely manner, further reducing the risk of battery cell 100 explosion and further improving the safety of battery cell 100 in use.

[0164] According to some embodiments of this application, such as Figure 14 and Figure 15 As shown, the second arc-shaped groove segment 391 is constructed in an arc shape, and the chamfer radius of the second arc-shaped groove segment 391 is greater than or equal to 1 mm.

[0165] The second arc-shaped groove segment 391 has an arc shape and a chamfer radius greater than or equal to 1 mm. The chamfer radius can be 1 mm, 1.5 mm, 2 mm, etc., and the upper limit of the chamfer radius can be set reasonably according to actual conditions. 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 section 30 due to stress concentration. Furthermore, when the internal pressure or temperature of the outer casing 20 reaches a threshold, after the crack initiation segment 32 cracks, it is easier for the crack initiation segment 32 to extend to the extension segment 33, further reducing the difficulty of flipping the pressure relief area 35. This allows the battery cell 100 to release pressure in a timely manner, further reducing the risk of battery cell 100 explosion and further improving the safety of battery cell 100 in use.

[0166] 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 1mm, 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 section 30 due to stress concentration. Furthermore, when the internal pressure or temperature of the outer casing 20 reaches the threshold, after the crack initiation segment 32 cracks, it is easier for the crack initiation segment 32 to extend the crack to the extension segment 33, further reducing the difficulty of flipping the pressure relief area 35. This allows the battery cell 100 to be depressurized in a timely manner, further reducing the risk of battery cell 100 explosion and further improving the safety of battery cell 100 in use.

[0167] According to some embodiments of this application, the crack initiation segment 32 is a straight segment extending along a first direction; or the crack initiation segment 32 is a straight segment extending along a second direction, the second direction being perpendicular to the first direction.

[0168] The electrode assembly 10 includes a positive electrode and a negative electrode. For example, the electrode assembly 10 includes at least one positive electrode and at least one negative electrode. The at least one positive electrode and at least one negative electrode are stacked to form the electrode assembly 10. At least a portion of the positive electrode and at least a portion of the negative electrode can be stacked along a first direction. When the battery cell 100 is in... Figure 3 When placed in the indicated direction, the first direction refers to... Figure 3 The electrode assembly 10 can also be a wound type, where the positive and negative electrode sheets of the electrode assembly 10 are wound together with a separator, and the positive and negative electrode portions are stacked along the first direction. Because the positive and negative electrode portions are stacked along the first direction, when the electrode assembly 10 expands, most of the expansion is concentrated in the first direction. Furthermore, the housing 20 may also include two second walls 22 connected to the first wall 21, with the two second walls 22 located on both sides of the electrode assembly 10 along the first direction.

[0169] As an example, the initiation segment 32 is a straight segment extending along the first direction, that is, the initiation segment 32 extends along the first direction, which is conducive to the initiation of cracks in the initiation segment 32 preferentially extending to the initiation segment 33.

[0170] As another example, such as Figure 3 As shown, the initiation segment 32 is a straight segment extending along the second direction, which is perpendicular to the first direction. When the battery cell 100... Figure 3 When placed in the center direction, the second direction refers to Figure 3 In the X direction. When the electrode assembly 10 expands, most of the expansion of the electrode assembly 10 is reflected in the first direction. Therefore, by setting the crack initiation section 32 as a straight section extending along the second direction, the crack initiation section 32 can be subjected to a greater force than the extension section 33, which is more conducive to the crack initiation section 32 preferentially extending to the extension section 33 to initiate cracking, so that the battery cell 100 can be depressurized in time, and the risk of battery cell 100 explosion can be further reduced.

[0171] In the above technical solution, by setting the crack initiation segment 32 as a straight segment extending along the first direction, it is beneficial for the crack initiation segment 32 to preferentially extend to the extension segment 33 for crack initiation. By setting the crack initiation segment 32 as a straight segment extending along the second direction, the force on the crack initiation segment 32 is greater than that on the extension segment 33, which is more conducive to the crack initiation segment 32 to preferentially extend to the extension segment 33 for crack initiation, so that the battery cell 100 can be depressurized in time, further reducing the risk of battery cell 100 explosion.

[0172] According to some embodiments of this application, the pressure relief part 30 is integrally formed with the first wall part 21; or, the pressure relief part 30 and the first wall part 21 are separately provided, the first wall part 21 is provided with a through hole, and the pressure relief part 30 is installed in the through hole.

[0173] In this design, when the pressure relief part 30 and the first wall part 21 are integrally formed, a groove 31 can be provided on the first wall part 21. The area where the groove 31 is provided on the first wall part 21 forms a weak zone. This simplifies the forming process of the pressure relief part 30 and reduces production costs. In this technical solution, by integrally forming the pressure relief part 30 and the first wall part 21, the forming process of the pressure relief part 30 is simple, reducing the number of components constituting the battery cell 100, simplifying the structure of the battery cell 100, and lowering the manufacturing cost of the battery cell 100.

[0174] Or, such as Figure 21 As shown, the pressure relief part 30 and the first wall part 21 are separately configured. The pressure relief part 30 and the outer shell 20 are two separate components, which are molded separately and then assembled together. Specifically, the pressure relief part 30 can be a component such as an explosion-proof plate, explosion-proof valve, or safety valve. The pressure relief part 30 can be installed on the first wall part 21 by means of bonding, welding, etc. The first wall part 21 is provided with a through hole, and the pressure relief part 30 is installed in the through hole. When the internal pressure or temperature of the outer shell 20 reaches a threshold, the pressure relief part 30 opens at least part of the through hole, and the discharge medium inside the battery cell 100 is discharged through the through hole to release the internal pressure of the battery cell 100. In the above technical solution, by constructing the pressure relief part 30 and the first wall part 21 as separate components, it is convenient to set the pressure relief part 30 on the outer shell 20, which is easy to manufacture and efficient, and can improve the production efficiency of the battery cell 100.

[0175] As an example, taking the pressure relief section 30 as an explosion-proof sheet, the explosion-proof sheet is a sheet body with at least a portion of its strength being less than the strength of the first wall portion 21. The explosion-proof sheet 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 sheet is at least partially destroyed, thereby opening at least a portion of the through hole to release the pressure inside the battery cell 100.

[0176] According to some embodiments of this application, such as Figure 21 As shown, the housing 20 includes a housing 23 and an end cap 24. The housing 23 has an opening on at least one side, the end cap 24 is connected to the housing 23 and is used to close the opening, and a first wall portion 21 is formed in the housing 23.

[0177] The housing 23 can be a hollow structure with an opening at one end, or it can be a hollow structure with openings at both opposite ends. The housing 23 can have various shapes, such as a prism. The end cap 24 is a component that closes the opening of the housing 23 to isolate the internal environment of the battery cell 100 from the external environment. The end cap 24 and the housing 23 together define a mounting cavity for accommodating the electrode assembly 10, electrolyte, and other components. The shape of the end cap 24 can be adapted to the shape of the housing 23. For example, if the housing 23 is a cuboid structure, the end cap 24 can be a rectangular plate structure adapted to the housing 23; or, if the housing 23 is a cylinder structure, the end cap 24 can be a circular plate structure adapted to the housing 23. The end cap 24 can also be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, or plastic. The end cap 24 and the housing 23 can be made of the same or different materials.

[0178] In an embodiment where the housing 23 has an opening at one end, one end cap 24 may be provided. In an embodiment where the housing 23 has openings at both opposite ends, two end caps 24 may be provided, with the two end caps 24 respectively closing the two openings of the housing 23, and the two end caps 24 and the housing 23 together defining the mounting cavity.

[0179] The housing 23 has a first wall portion 21 and a second wall portion 22. The first wall portion 21 is formed on the housing 23. The pressure relief portion 30 can be integrally formed with the housing 23 or it can be separately set from the housing 23. By setting the pressure relief portion 30 on the housing 23, the structure of the end cap 24 can be simplified. 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. This shortens the path of the discharge medium to the pressure relief portion 30 during pressure relief and shortens the time for the discharge medium to reach the pressure relief portion 30, thereby improving the timeliness of pressure relief of the battery cell 100 and effectively improving the reliability of the battery cell 100.

[0180] In the above technical solution, by forming the first wall portion 21 on the housing 23, the structure of the end cover 24 can be simplified, and the distance between the pressure relief portion 30 and the main body of the electrode assembly 10 can be shortened. This shortens the path of the discharge medium to the pressure relief portion 30 during pressure relief, shortens the time for the discharge medium to reach the pressure relief portion 30, improves the timeliness of pressure relief of the battery cell 100, and thus effectively improves the reliability of the battery cell 100.

[0181] According to some embodiments of this application, the housing 23 has openings on opposite sides, and two end caps 24 are used to close the openings on the corresponding sides.

[0182] In an embodiment where the housing 23 has openings at opposite 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 the mounting cavity. Furthermore, the end caps 24 are provided with electrical connection terminals 25, which are electrically connected to the positive electrode or the negative electrode. The electrical connection terminal 25 can be part of the end cover 24, or it can be a terminal post mounted on the end cover 24. Typically, there are two electrical connection terminals 25. One electrical connection terminal 25 is a positive terminal post and is electrically connected to the tab of the positive electrode plate, and the other electrical connection terminal 25 is a negative terminal post and is electrically connected to the tab of the negative electrode plate, so as to input or output the electrical energy of the battery cell 100. The electrical connection terminal 25 and the tab can be directly connected, for example, the electrical connection terminal 25 and the tab can be directly welded. The electrical connection terminal 25 and the tab can also be indirectly connected, for example, the electrical connection terminal 25 and the tab can be indirectly connected through a current collector. The current collector can be a metal conductor, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0183] In the above technical solution, the housing 23 has openings on both sides, and the two end caps 24 are used to close the openings on the corresponding sides, which can jointly define the mounting cavity. In addition, it can facilitate the manufacturing and molding of the housing 23, and at the same time facilitate the electrode assembly 10 to lead out the electrode tabs from both ends, thereby facilitating the separate arrangement of the two electrical connection terminals 25 and reducing the risk of short circuit of the battery cell 100.

[0184] According to some embodiments of this application, such as Figure 21 As shown, the first wall portion 21 is used to support the electrode assembly 10 and is located below the electrode assembly 10.

[0185] The housing 23 has a bottom wall that is opposite to and spaced apart from the end cap 24. The bottom wall is constructed as a first wall portion 21, which can support the electrode assembly 10.

[0186] In the above technical solution, the electrode assembly 10 is supported by the first wall portion 21, which allows the electrode assembly 10 to be stably installed in the mounting cavity of the housing 20.

[0187] According to some embodiments of this application, such as Figure 3 and Figure 4 As shown, the housing 20 includes a housing 23 and an end cap 24. The housing 23 has an opening on at least one side, the end cap 24 is connected to the housing 23 and is used to close the opening, and a first wall portion 21 is formed on the end cap 24.

[0188] The housing 23 can be a hollow structure with an opening at one end, or it can be a hollow structure with openings at both opposite ends. The housing 23 can have various shapes, such as a prism. The end cap 24 is a component that closes the opening of the housing 23 to isolate the internal environment of the battery cell 100 from the external environment. The end cap 24 and the housing 23 together define a mounting cavity for accommodating the electrode assembly 10, electrolyte, and other components. The shape of the end cap 24 can be adapted to the shape of the housing 23. For example, if the housing 23 is a cuboid structure, the end cap 24 can be a rectangular plate structure adapted to the housing 23; or, if the housing 23 is a cylinder structure, the end cap 24 can be a circular plate structure adapted to the housing 23. The end cap 24 can also be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, or plastic. The end cap 24 and the housing 23 can be made of the same or different materials.

[0189] In an embodiment where the housing 23 has an opening at one end, one end cap 24 may be provided. In an embodiment where the housing 23 has openings at both opposite ends, two end caps 24 may be provided, with the two end caps 24 respectively closing the two openings of the housing 23, and the two end caps 24 and the housing 23 together defining the mounting cavity.

[0190] In the above technical solution, by setting the pressure relief part 30 on the end cover 24, the structure of the housing 23 can be simplified and the production efficiency of the housing 23 can be improved.

[0191] like Figure 5 As shown, the pressure relief section 30 in the first embodiment is oblong. (As indicated...) Figure 12 As shown, the pressure relief section 30 in the second embodiment is rectangular. (As indicated...) Figure 14 As shown in the schematic diagram of the pressure relief section 30 of the third embodiment, compared with the pressure relief section 30 of the second embodiment, the pressure relief section 30 of the third embodiment is provided with a second arc-shaped groove section 391.

[0192] like Figure 11 As shown, the cross-section of the groove 31 is square. Figure 16 As shown, the cross-section of the groove 31 is trapezoidal. Figure 17 As shown, the cross-section of the groove 31 is semi-circular. Figure 18 As shown, the cross-section of the groove 31 is triangular. Figure 19 As shown, the cross-section of the groove 31 is oblong. Figure 20 As shown, grooves 31 are formed on both sides of the pressure relief part 30. The grooves 31 on both sides of the pressure relief part 30 are arranged opposite to each other, and the bottom of the groove 31 is formed between the two grooves 31 on both sides. The two grooves 31 on both sides share the bottom of one groove 31.

[0193] According to some embodiments of this application, this application also provides a battery 200, including the battery cell 100 in the above embodiments.

[0194] According to some embodiments of this application, this application also provides an electrical device 300, including the battery 200 in the above embodiments.

[0195] According to some embodiments of this application, see Figure 21 As shown, this application provides a battery cell 100, which includes a housing 20 and an electrode assembly 10. The housing 20 includes a shell 23 and an end cap 24, which are connected and together define a mounting cavity. The electrode assembly 10 is mounted in the mounting cavity. The bottom wall of the shell 23 is constructed as a first wall portion 21, and a pressure relief portion 30 is provided on the bottom wall of the shell 23. The pressure relief portion 30 has a scoring groove 31, and the bottom of the scoring groove 31 has a connected crack initiation section 32 and an extension section 33. The pressure relief portion 30 is configured such that when the internal pressure or temperature of the housing 20 reaches a threshold, the crack initiation section 32 cracks before the extension section 33.

[0196] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0197] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0198] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A battery cell, characterized in that, include: Electrode assembly; A housing for accommodating the electrode assembly, the housing including a first wall portion; A pressure relief section is provided on the first wall portion. The pressure relief section has a groove, and the bottom of the groove has a connected crack initiation segment, a main body segment, and two extension segments. The crack initiation segment and the main body segment are opposite to each other and spaced apart. Both the crack initiation segment and the main body segment extend along a direction perpendicular to the thickness of the battery cell. One extension segment connects one end of the crack initiation segment and one end of the main body segment, and the other extension segment connects the other end of the crack initiation segment and the other end of the main body segment. The length of the crack initiation segment is greater than the length of the extension segment. The pressure relief section is configured to relieve pressure when the internal pressure of the casing... When the force or temperature reaches a threshold, the initiating crack segment cracks before the extending segment. The thickness of the extending segment is less than the thickness of the initiating crack segment. The ratio of the thickness of the initiating crack segment to the thickness of the extending segment is greater than or equal to 1.05 and less than or equal to 2.

1. The thickness of the initiating crack segment is less than the thickness of the main body segment. The thickness of the initiating crack segment is greater than or equal to 0.05 mm and less than or equal to 0.31 mm. The scoring groove is an annular structure, and the inner edge of the scoring groove defines a pressure relief area. The pressure relief area is elongated, and the ratio of the maximum length of the pressure relief area to the maximum width of the pressure relief area is greater than 1.2 and less than 5.

5.

2. The battery cell according to claim 1, characterized in that, The groove includes two first straight groove segments and two first arc-shaped groove segments. Both first straight groove segments extend along the thickness direction perpendicular to the battery cell. The two ends of each first straight groove segment are connected to the two first arc-shaped groove segments respectively to make the groove structure annular. The length of the first straight groove segment is greater than the length of the first arc-shaped groove segment. The bottom of one first straight groove segment has the crack initiation segment, the bottom of the other first straight groove segment has the main body segment, and the bottom of the first arc-shaped groove segment has the extension segment.

3. The battery cell according to claim 1, characterized in that, The groove includes two second straight groove segments and two third straight groove segments. The two second straight groove segments extend along the thickness direction perpendicular to the battery cell. The two ends of each second straight groove segment are connected to the two third straight groove segments respectively so that the groove is annular. The length of the second straight groove segment is greater than the length of the third straight groove segment. The bottom of one second straight groove segment has the crack initiation segment, the bottom of the other second straight groove segment has the main body segment, and the bottom of the third straight groove segment has the extension segment.

4. The battery cell according to claim 3, characterized in that, The groove also includes a second arc-shaped groove segment, and the second straight groove segment is connected to the third straight groove segment through the second arc-shaped groove segment.

5. The battery cell according to claim 4, characterized in that, The second arc-shaped groove segment is constructed in an arc shape, and the chamfer radius of the second arc-shaped groove segment is greater than or equal to 1mm.

6. The battery cell according to claim 1, characterized in that, The crack initiation segment is a straight segment.

7. The battery cell according to claim 1, characterized in that, The pressure relief section is integrally formed with the first wall section; or... The pressure relief part is separately disposed from the first wall part, the first wall part is provided with a through hole, and the pressure relief part is installed in the through hole.

8. The battery cell according to claim 1, characterized in that, The housing includes a shell and an end cap, the shell having an opening on at least one side, the end cap being connected to the shell and used to close the opening, and a first wall portion being formed in the shell.

9. The battery cell according to claim 8, characterized in that, The housing has openings on opposite sides, and the two end caps are used to close the openings on the corresponding sides.

10. The battery cell according to claim 8, characterized in that, The first wall portion is used to support the electrode assembly and is located below the electrode assembly.

11. The battery cell according to claim 1, characterized in that, The housing includes a shell and an end cap, the shell having an opening on at least one side, the end cap being connected to the shell and used to close the opening, and a first wall portion being formed in the end cap.

12. A battery, characterized in that, Includes the battery cell according to any one of claims 1-11.

13. An electrical appliance, characterized in that, Includes the battery according to claim 12.

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