Battery cell, manufacturing method and system thereof, battery and electric device

Abstract

The embodiments of the present application provide a battery cell, a manufacturing method and a manufacturing system thereof, a battery, and an electrical device. The battery cell includes: a shell having an opening; an electrode assembly housed in the shell, the electrode assembly being provided with a first tab at the end facing the opening; an end cover for covering the opening, the end cover including a first connection portion and a weak portion, the weak portion being provided along the edge of the first connection portion, and the end cover being configured to rupture along the weak portion when the internal pressure of the battery cell reaches a threshold value to release the internal pressure. The battery cell also includes a fixing structure, the fixing structure being used to fix the first connection portion to the first tab to limit the movement of the first connection portion. The embodiments of the present application can reduce the risk of the end cover rupturing and releasing pressure prematurely under normal use of the battery cell, which is beneficial to improving the safety and stability of the battery cell.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more particularly, to a battery cell and a manufacturing method and system thereof, a battery, and an electrical device. Background Art

[0002] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and power tools. Battery cells can include nickel-cadmium battery cells, nickel-metal hydride battery cells, lithium-ion battery cells, and secondary alkaline zinc-manganese battery cells.

[0003] In the development of battery technology, in addition to improving the performance of battery cells, safety is also an issue that cannot be ignored. If the safety of a battery cell cannot be guaranteed, the battery cell will be unusable. Therefore, how to enhance the safety of battery cells is a technical issue that needs to be addressed urgently in battery technology. Summary of the Invention

[0004] The present application provides a battery cell, a manufacturing method and a manufacturing system thereof, a battery, and an electrical device, which can improve the safety of the battery cell.

[0005] In a first aspect, an embodiment of the present application provides a battery cell, comprising:

[0006] a housing having an opening;

[0007] An electrode assembly is accommodated in the housing, and a first electrode tab is provided at one end of the electrode assembly facing the opening;

[0008] an end cap, configured to cover the opening, the end cap comprising a first connecting portion and a weakened portion, the weakened portion being arranged along an edge of the first connecting portion, the end cap being configured to rupture along the weakened portion when the internal pressure of the battery cell reaches a threshold value to release the internal pressure;

[0009] The battery cell further includes a fixing structure, which is used to fix the first connecting portion to the first tab to limit movement of the first connecting portion.

[0010] In the above scheme, the first connecting portion of the end cover is fixedly connected to the first pole ear of the electrode assembly through a fixed structure. In this way, the first pole ear of the electrode assembly can limit the movement of the first connecting portion during the use of the battery cell, thereby reducing the deformation and flipping of the end cover, reducing the alternating stress borne by the weak portion, slowing down the fatigue aging of the weak portion of the end cover, and reducing the risk of the end cover rupturing and releasing pressure prematurely under normal use of the battery cell, which is beneficial to improving the safety and stability of the battery cell.

[0011] In some embodiments, the first connecting portion is electrically connected to the first tab via a fixing structure.

[0012] In the above solution, the end cap can be charged and can serve as the output pole of the battery cell, thereby eliminating a traditional electrode terminal and simplifying the structure of the battery cell.

[0013] In some embodiments, the fixing structure is configured to be at least partially broken when the internal pressure of the battery cell reaches a threshold value to disconnect the first connecting portion from the first tab.

[0014] In the above scheme, after the connection between the first connecting part and the first electrode tab is disconnected, the first electrode tab will no longer restrict the movement of the first connecting part; as the weak part ruptures, the first connecting part can be opened by air pressure to increase the channel for releasing internal pressure, thereby quickly releasing internal pressure and improving safety.

[0015] In some embodiments, the fixing structure is a welding portion formed by welding the first electrode tab and the first connecting portion.

[0016] In the above solution, the first connecting portion and the first electrode tab are directly connected by welding, which can simplify the structure of the battery cell.

[0017] In some embodiments, the battery cell further includes a current collecting member disposed between the end cap and the first tab. The current collecting member is configured to connect the first connecting portion and the first tab to achieve electrical connection between the end cap and the first tab. The fixing structure includes a first fixing structure and a second fixing structure. The first fixing structure is a weld formed by welding a portion of the current collecting member to the first tab, and the second fixing structure is a weld formed by welding another portion of the current collecting member to the first connecting portion.

[0018] In the above solution, a current collecting member is provided in the battery cell and welded to the first connecting portion and the first tab, respectively, to achieve electrical connection between the end cap and the first tab. The current collecting member can be tightly fitted to the first connecting portion, reducing the risk of microcracks in the first connecting portion, improving sealing performance, and reducing safety hazards.

[0019] In some embodiments, the current collecting component includes a first current collecting part and a second current collecting part, the first current collecting part surrounds the outside of the second current collecting part, the first fixed structure is a welding part formed by welding the first current collecting part and the first electrode tab, and the second fixed structure is a welding part formed by welding the second current collecting part and the first connecting part.

[0020] In the above solution, the first fixing structure and the second fixing structure are respectively formed on the first collecting part and the second collecting part, so that the first fixing structure can avoid affecting the welding of the first connecting part and the current collecting component, thereby improving the connection strength between the first connecting part and the current collecting component.

[0021] In some embodiments, the second fixing structure is configured to be broken when the internal pressure of the battery cell reaches a threshold value to disconnect the second current collecting part from the first connecting part.

[0022] In the above scheme, after the connection between the first connecting part and the second current collecting part is disconnected, the first electrode ear will no longer restrict the movement of the first connecting part through the current collecting component; as the weak part ruptures, the first connecting part can be opened by air pressure to increase the channel for releasing internal pressure, thereby quickly releasing the internal pressure and improving safety.

[0023] In some embodiments, the connection strength between the second current collecting portion and the first connecting portion is less than the connection strength between the first current collecting portion and the first electrode tab.

[0024] In the above scheme, when thermal runaway occurs in the battery cell, the end cover applies tension to the current collecting member and the first electrode tab under the action of gas pressure; since the connection strength between the second current collecting part and the first connecting part is less than the connection strength between the first current collecting part and the first electrode tab, the current collecting member will first separate from the first connecting part; after the current collecting member separates from the first connecting part, the current collecting member will not be subjected to the tension of the end cover, thereby maintaining the fixed connection between the current collecting member and the first electrode tab, reducing the risk of the current collecting member blocking the channel for releasing internal pressure.

[0025] In some embodiments, the first connecting portion includes a first protrusion and a first plate surrounding the outer side of the first protrusion. The first protrusion protrudes from the inner surface of the first plate in a direction facing the electrode assembly. A first recess is formed on the first connecting portion at a position corresponding to the first protrusion and recessed from the outer surface of the first plate in a direction facing the electrode assembly. The weak portion is located on the outer side of the first plate and is arranged along the outer edge of the first plate. The second current collecting portion abuts against and is welded to the first protrusion to form a second fixing structure.

[0026] In the above solution, the first concave portion reduces the strength of the first convex portion and increases its elasticity. Thus, when the battery cell vibrates, the first convex portion can release stress through deformation, reducing the stress transferred to the weak portion and slowing fatigue aging of the weak portion. The first concave portion also reduces the thickness of the first convex portion, reducing the energy required to weld the first convex portion to the second current collecting portion, reducing the heat transferred to the weak portion and slowing fatigue aging of the weak portion.

[0027] In some embodiments, the first current collecting portion covers the weak portion in a thickness direction of the end cover.

[0028] In the above solution, the current collecting member can separate the weak portion from the first electrode tab to reduce the number of active particles in the electrode assembly falling onto the weak portion, thereby reducing the risk of corrosion of the weak portion.

[0029] In some embodiments, the first protrusion supports the current collecting member to form an escape gap between the first current collecting portion and the end cover for escaping the weak portion.

[0030] In this solution, the first connection portion supports the first tab via the current collecting member, reducing the vibration of the electrode assembly during battery cell vibration and improving its stability. The clearance separates the weak portion from the first current collecting portion, preventing the first current collecting portion from blocking the channel for relieving internal pressure if the weak portion ruptures, thereby improving safety.

[0031] In some embodiments, the electrode assembly is a wound structure, the electrode assembly has a first through hole at the center of the winding, and the second current collecting portion is provided with a second through hole, which is arranged opposite to the first through hole to guide the gas in the electrode assembly to the first connecting portion.

[0032] In the above solution, when the electrode assembly thermally runs away, high-temperature and high-pressure gas can act on the first connecting portion through the first through hole and the second through hole, thereby quickly disconnecting the first connecting portion and the current collecting member.

[0033] In some embodiments, the end cap further includes a second connecting portion, the second connecting portion surrounding the outside of the first connecting portion and being used for fixed connection with the housing. The weak portion is located between the first connecting portion and the second connecting portion and is used for connecting the first connecting portion and the second connecting portion.

[0034] In the above solution, the end cover is fixed to the shell through the second connecting portion surrounding the outside of the weak portion, so as to increase the distance between the weak portion and the shell, reduce the stress transmitted to the weak portion, and slow down the fatigue aging of the weak portion.

[0035] In some embodiments, the weak portion is configured to rupture and disconnect the first connection portion from the second connection portion when the internal pressure of the battery cell reaches a threshold value.

[0036] In the above solution, after the connection between the first connection part and the second connection part is disconnected, the first connection part and the second connection part can be flipped outward under the action of internal pressure to increase the channel for releasing the internal pressure, thereby quickly releasing the internal pressure and improving safety.

[0037] In some embodiments, the second connecting portion includes a second plate and a second protrusion surrounding the outer side of the second plate. The second protrusion protrudes from the inner surface of the second plate in a direction facing the electrode assembly. A second recessed portion is formed on the second connecting portion at a position corresponding to the second protrusion and recessed from the outer surface of the second plate in a direction facing the electrode assembly. The second plate surrounds the outer side of the weak portion, and the second protrusion is configured to be fixedly connected to the housing.

[0038] In the above solution, the second concave portion can reduce the strength of the second convex portion and increase the elasticity of the second convex portion. In this way, when the battery cell vibrates, the stress on the shell is transferred to the second convex portion, and the second convex portion can release the stress by deformation to reduce the stress transferred to the weak portion and slow down the fatigue aging of the weak portion.

[0039] In some embodiments, the outer side surface of the second protrusion abuts against the inner surface of the shell and is used to be welded to the shell to close the opening.

[0040] In the above solution, welding can achieve a seal, reduce the risk of electrolyte leakage, and improve the connection strength and current carrying capacity between the second protrusion and the housing. The second recess can reduce the strength of the second protrusion and increase its elasticity. Therefore, during the welding process of the second protrusion and the housing, the second protrusion can release welding stress through deformation, thereby reducing the risk of deformation and cracking in the weld area, reducing the welding stress transmitted to weak parts, and improving safety.

[0041] In some embodiments, the second protrusion abuts against the first tab to support the first tab.

[0042] In the above solution, the second protrusion supports the first electrode tab to reduce the shaking amplitude of the electrode assembly when the battery cell vibrates, thereby improving the stability of the electrode assembly.

[0043] In some embodiments, the weakened portion surrounds the first connecting portion.

[0044] In the above solution, the weak portion surrounds the first connecting portion, which can increase the range of the weak portion, increase the exhaust rate when the weak portion ruptures, and improve safety.

[0045] In some embodiments, the end cap is provided with a groove, and a region of the end cap opposite to the groove forms a weak portion.

[0046] In the above solution, the thickness and strength of the weak portion are reduced by providing the groove, so that the end cover can be broken along the weak portion when the internal pressure of the battery cell reaches a threshold.

[0047] In some embodiments, the end cap includes a first nickel layer, a steel layer, and a second nickel layer, wherein the first nickel layer is disposed on a surface of the steel layer facing the first electrode tab, and the second nickel layer is disposed on a surface of the steel layer facing away from the first electrode tab. The groove is recessed from the surface of the first nickel layer facing away from the steel layer in a direction toward the second nickel layer, and the depth of the groove is greater than the thickness of the first nickel layer and less than the sum of the thicknesses of the first nickel layer and the steel layer.

[0048] In the above solution, the groove is located on the inner side of the end cover and will not damage the second nickel layer on the outside during the molding process, so the second nickel layer can protect the steel layer from the outside to reduce the risk of corrosion of the steel layer; the steel layer itself is not easily corroded by the electrolyte, so even if the groove exposes the steel layer, it is not easy to cause safety risks.

[0049] In some embodiments, the end cap is used to electrically connect the first tab to the housing.

[0050] In the above solution, the shell itself can serve as the output pole of the battery cell. When multiple battery cells are assembled into a group, the shell can be electrically connected to the busbar component, which can not only increase the flow area but also make the structural design of the busbar component more flexible.

[0051] In some embodiments, the housing further includes sidewalls and a bottom wall connected to the sidewalls. The sidewalls extend along the thickness of the end cap and surround the periphery of the electrode assembly. The bottom wall is provided with an electrode lead-out hole. The electrode assembly further includes a second tab having opposite polarity to the first tab, the second tab being disposed at an end of the electrode assembly facing away from the outlet. The battery cell further includes an electrode terminal mounted in the electrode lead-out hole, the electrode terminal being electrically connected to the second tab.

[0052] In the above solution, the bottom wall and electrode terminals can serve as the two output poles of the battery cell, which can simplify the battery cell structure and ensure the battery cell's current carrying capacity. The bottom wall and electrode terminals are located at the same end of the battery cell. Therefore, when multiple battery cells are assembled into a group, the current collecting component can be assembled on the same side of the battery cells, which can simplify the assembly process and improve assembly efficiency.

[0053] In some embodiments, the bottom wall and the side walls are integrally formed structures.

[0054] The above solution can omit the process of connecting the bottom wall and the side wall.

[0055] In some embodiments, the first electrode tab is a negative electrode tab, and the base material of the shell is steel.

[0056] In the above solution, the housing is electrically connected to the negative electrode tab, meaning the housing is in a low-potential state. The steel housing is less susceptible to corrosion by the electrolyte in this low-potential state, thus reducing safety risks.

[0057] In some embodiments, the battery cells are cylindrical battery cells.

[0058] In a second aspect, an embodiment of the present application provides a battery comprising a plurality of battery cells according to any one of the embodiments of the first aspect.

[0059] In a third aspect, an embodiment of the present application provides an electrical device, comprising the battery of the second aspect, the battery being used to provide electrical energy.

[0060] In a fourth aspect, an embodiment of the present application provides a method for manufacturing a battery cell, comprising:

[0061] providing a housing having an opening;

[0062] Providing an electrode assembly and installing the electrode assembly into the housing, wherein the electrode assembly is provided with a first electrode tab at one end facing the opening;

[0063] Providing an end cover and connecting the end cover to the housing so that the end cover covers the opening, the end cover comprising a first connecting portion and a weakened portion, the weakened portion being arranged along an edge of the first connecting portion;

[0064] The first connecting portion is fixedly connected to the first electrode tab to form a fixed structure to limit the movement of the first connecting portion;

[0065] The end cap is configured to rupture along a weak portion when the internal pressure of the battery cell reaches a threshold value to release the internal pressure.

[0066] In a fifth aspect, an embodiment of the present application provides a battery cell manufacturing system, comprising:

[0067] A first providing device is used to provide a housing having an opening;

[0068] A second providing device is used to provide an electrode assembly and install the electrode assembly into the housing, wherein the electrode assembly is provided with a first electrode tab at one end facing the opening;

[0069] A third providing device is used to provide an end cover and connect the end cover to the housing so that the end cover covers the opening, the end cover including a first connecting portion and a weakened portion, the weakened portion being provided along an edge of the first connecting portion;

[0070] An assembly device, used to fixedly connect the first connecting portion to the first tab and form a fixed structure to limit movement of the first connecting portion;

[0071] The end cap is configured to rupture along a weak portion when the internal pressure of the battery cell reaches a threshold value to release the internal pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0073] Figure 1 A schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0074] Figure 2 An exploded schematic diagram of a battery provided in some embodiments of the present application;

[0075] Figure 3 for Figure 2 An exploded schematic diagram of the battery module shown;

[0076] Figure 4 An exploded schematic diagram of a battery cell provided in some embodiments of the present application;

[0077] Figure 5 A schematic cross-sectional view of a battery cell provided in some embodiments of the present application;

[0078] Figure 6 for Figure 5 An enlarged schematic diagram of a battery cell at circle A is shown;

[0079] Figure 7 for Figure 4 A partial cross-sectional schematic diagram of the end cap shown;

[0080] Figure 8 Schematic cross-sectional views of battery cells provided in other embodiments of the present application;

[0081] Figure 9 for Figure 8 An enlarged schematic diagram of a battery cell shown at box B;

[0082] Figure 10 A schematic flow chart of a method for manufacturing a battery cell according to some embodiments of the present application;

[0083] Figure 11 A schematic block diagram of a battery cell manufacturing system provided in some embodiments of the present application.

[0084] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0085] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0086] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0087] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0088] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0089] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0090] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0091] The term "plurality" used in this application refers to two or more (including two).

[0092] In this application, battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, and the embodiments of this application are not limited thereto. Battery cells may be cylindrical, flat, rectangular, or in other shapes, and the embodiments of this application are not limited thereto.

[0093] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0094] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell primarily relies on the movement of metal ions between the positive and negative electrode sheets to operate. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector. The positive current collector includes a positive coating area and a positive electrode tab connected to the positive coating area. The positive coating area is coated with the positive active material layer, while the positive electrode tab is not coated with the positive active material layer. Taking lithium-ion batteries as an example, the material of the positive current collector can be aluminum, and the positive active material layer includes a positive active material. The positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode sheet includes a negative current collector and a negative active material layer, which is coated on the surface of the current collector. The negative current collector includes a negative coating region and a negative tab connected to the negative coating region. The negative coating region is coated with the negative active material layer, while the negative tab is not coated with the negative active material layer. The negative current collector can be made of copper, and the negative active material layer includes a negative active material, which can be carbon or silicon. The separator can be made of materials such as PP (polypropylene) or PE (polyethylene).

[0095] The battery cell further includes a housing and an end cap. The housing has an opening and is used to accommodate the electrode assembly. The electrode assembly can be assembled into the housing through the opening of the housing. The end cap is used to cover the opening of the housing to achieve sealing.

[0096] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery safety must also be considered.

[0097] The pressure relief mechanism on a battery cell has a significant impact on its safety. For example, short circuits, overcharging, and other events can cause thermal runaway within the cell, leading to a sudden increase in pressure. In these situations, the pressure relief mechanism activates to release the internal pressure, preventing explosion or fire.

[0098] A pressure relief mechanism is a component or element that activates to release internal pressure when the internal pressure of a battery cell reaches a predetermined threshold. This threshold varies depending on the design requirements. It may depend on the materials of one or more of the positive and negative electrode plates, electrolyte, and separator in the battery cell.

[0099] The pressure relief mechanism may be in the form of an explosion-proof valve, an air valve, a pressure relief valve or a safety valve, and may specifically be a pressure-sensitive element or structure, that is, when the internal pressure of the battery cell reaches a predetermined threshold, the pressure relief mechanism executes an action or a weak portion provided in the pressure relief mechanism ruptures, thereby forming an opening or channel for the internal pressure to be released.

[0100] The "activation" mentioned in this application refers to the action of the pressure relief mechanism or its activation to a certain state, thereby allowing the internal pressure of the battery cell to be released. The action produced by the pressure relief mechanism may include, but is not limited to: at least a portion of the pressure relief mechanism is ruptured, broken, torn or opened, etc. When the pressure relief mechanism is actuated, the high-temperature and high-pressure substances inside the battery cell will be discharged outward from the actuated part as emissions. In this way, the pressure of the battery cell can be relieved under controllable pressure, thereby avoiding potential more serious accidents.

[0101] The emissions from battery cells mentioned in this application include but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0102] To simplify the battery cell structure, the inventors attempted to integrate a pressure relief mechanism into the end cap. For example, the inventors designed a weak portion in the end cap, which is configured to rupture along the weak portion when the internal pressure of the battery cell reaches a threshold, releasing the internal pressure. When a short circuit or overcharge occurs, thermal runaway can occur within the battery cell, causing a sudden pressure increase. In this case, the rupture of the weak portion releases the internal pressure outward, preventing the battery cell from exploding or catching fire, thereby improving safety.

[0103] However, after the inventors discovered that battery cells could explode and release pressure before the internal pressure reached the predetermined threshold, they analyzed and studied the structure and operating environment of the battery cells. The inventors discovered that the weak portion of the end cap was experiencing premature fatigue aging, which resulted in a decrease in the end cap's opening threshold. This weak portion of the end cap would rupture prematurely before the internal pressure of the battery cell reached the predetermined threshold. Further research revealed that during transportation, temperature changes, or charging and discharging, the internal pressure of the battery cell fluctuated between high and low, causing the end cap to flip back and forth. Long-term back and forth movement of the end cap would cause fatigue aging in the weak portion, resulting in a decrease in the end cap's opening threshold.

[0104] In view of this, an embodiment of the present application provides a technical solution, which limits the flipping of the end cover by fixing the end cover to the pole ear of the electrode assembly, reduces the alternating stress borne by the weak part, slows down the fatigue aging of the weak part of the end cover, and reduces the risk of premature rupture and pressure release of the end cover, which is beneficial to improving the safety and stability of the battery cell.

[0105] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0106] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0107] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0108] Figure 1 This is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application. Figure 1 As shown, a battery 2 is provided inside the vehicle 1, and the battery 2 can be provided at the bottom, head, or tail of the vehicle 1. The battery 2 can be used to power the vehicle 1, for example, the battery 2 can be used as an operating power source for the vehicle 1.

[0109] The vehicle 1 may further include a controller 3 and a motor 4 . The controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of the vehicle 1 during startup, navigation, and driving.

[0110] In some embodiments of the present application, the battery 2 can not only serve as the operating power source of the vehicle 1, but also serve as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0111] Figure 2 Schematic diagram of the explosion of the battery provided in some embodiments of the present application. Figure 2 As shown, the battery 2 includes a box 5 and a battery cell ( Figure 2 The battery cells are housed in the box body 5 .

[0112] The housing 5 is used to house battery cells and can have various structures. In some embodiments, the housing 5 can include a first housing portion 5a and a second housing portion 5b. The first housing portion 5a and the second housing portion 5b overlap each other, and the first housing portion 5a and the second housing portion 5b together define a storage space 5c for accommodating the battery cells. The second housing portion 5b can be a hollow structure with one end open. The first housing portion 5a is a plate-like structure, and the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. The first housing portion 5a and the second housing portion 5b can also be hollow structures with one end open. The open side of the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0113] In order to improve the sealing performance after the first box body 5a and the second box body 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 5a and the second box body 5b.

[0114] Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box body.

[0115] In battery 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections. Multiple battery cells can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire battery module can be housed within housing 5. Alternatively, multiple battery cells can be first connected in series, in parallel, or in a hybrid configuration to form a battery module 6, and then multiple battery modules 6 can be connected in series, in parallel, or in a hybrid configuration to form a single unit housed within housing 5.

[0116] Figure 3 for Figure 2 An exploded diagram of the battery module is shown.

[0117] In some embodiments, as Figure 3 As shown, there are multiple battery cells 7, which are first connected in series, in parallel, or in mixed series to form a battery module 6. The multiple battery modules 6 are then connected in series, in parallel, or in mixed series to form a whole, which is accommodated in a box.

[0118] The multiple battery cells 7 in the battery module 6 can be electrically connected via a busbar component to achieve parallel connection, series connection, or mixed connection of the multiple battery cells 7 in the battery module 6 .

[0119] Figure 4 An exploded schematic diagram of a battery cell provided in some embodiments of the present application; Figure 5A schematic cross-sectional view of a battery cell provided in some embodiments of the present application; Figure 6 for Figure 5 An enlarged schematic diagram of a battery cell at circle A is shown.

[0120] like Figures 4 to 6 As shown, the battery cell 7 of the present embodiment includes: a housing 20 having an opening 21; an electrode assembly 10 housed within the housing 20, with a first tab 11 provided at one end of the electrode assembly 10 facing the opening 21; and an end cap 30 for covering the opening 21. The end cap 30 includes a first connecting portion 31 and a weakened portion 32, with the weakened portion 32 disposed along the edge of the first connecting portion 31. The end cap 30 is configured to rupture along the weakened portion 32 to release the internal pressure when the internal pressure of the battery cell 7 reaches a threshold. The battery cell 7 also includes a fixing structure 60 for fixing the first connecting portion 31 to the first tab 11 to restrict movement of the first connecting portion 31.

[0121] The electrode assembly 10 includes a first electrode plate, a second electrode plate, and a separator, wherein the separator is used to separate the first electrode plate and the second electrode plate. The polarity of the first electrode plate and the second electrode plate are opposite. In other words, one of the first electrode plate and the second electrode plate is a positive electrode plate, and the other of the first electrode plate and the second electrode plate is a negative electrode plate.

[0122] Optionally, the first pole piece, the second pole piece and the separator are all strip-shaped structures, and the first pole piece, the second pole piece and the separator are wound together to form a wound structure. The wound structure can be a cylindrical structure, a flat structure or a structure of other shapes.

[0123] The electrode assembly 10 includes a main body 12, a first electrode tab 11, and a second electrode tab 13. The first electrode tab 11 and the second electrode tab 13 protrude from the main body 12. The first electrode tab 11 is the portion of the first electrode sheet not coated with the active material layer, and the second electrode tab 13 is the portion of the second electrode sheet not coated with the active material layer. Accordingly, one of the first electrode tab 11 and the second electrode tab 13 is a positive polarity tab, and the other is a negative polarity tab.

[0124] The first electrode tab 11 and the second electrode tab 13 may extend from the same side of the main body 12 , or may extend from opposite sides thereof.

[0125] Exemplarily, the first electrode tab 11 and the second electrode tab 13 are respectively provided on both sides of the main body 12. In other words, the first electrode tab 11 and the second electrode tab 13 are respectively provided at both ends of the electrode assembly 10. Optionally, the first electrode tab 11 is located at the end of the electrode assembly 10 facing the end cap 30, and the second electrode tab 13 is located at the end of the electrode assembly 10 facing away from the end cap 30.

[0126] Optionally, the first pole tab 11 is wound around the central axis X of the electrode assembly 10 in multiple turns. In other words, the first pole tab 11 includes multiple turns of pole tab layers. After the winding is completed, the first pole tab 11 is generally cylindrical, and a gap is left between two adjacent turns of pole tab layers. In the embodiment of the present application, the first pole tab 11 can be processed to reduce the gap between the pole tab layers to facilitate the connection of the first pole tab 11 with other electrical structures. For example, in the embodiment of the present application, the first pole tab 11 can be flattened to make the end area of ​​the first pole tab 11 away from the main body 12 gather and gather together; the flattening process forms a dense end face at the end of the first pole tab 11 away from the main body 12, reducing the gap between the pole tab layers, and facilitating the connection of the first pole tab 11 with other conductive structures. Alternatively, in the embodiment of the present application, conductive material can also be filled between two adjacent turns of pole tab layers to reduce the gap between the pole tab layers.

[0127] Optionally, the second electrode tab 13 is wound multiple times around the central axis X of the electrode assembly 10, and the second electrode tab 13 includes multiple electrode tab layers. Exemplarily, the second electrode tab 13 is also flattened to reduce gaps between the electrode tab layers of the second electrode tab 13.

[0128] The housing 20 may be a hollow structure with one side open or a hollow structure with two sides open. The end cap 30 covers the opening of the housing 20 and forms a sealed connection to form a receiving cavity for accommodating the electrode assembly and the electrolyte.

[0129] The housing 20 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 has a cylindrical structure, a cylindrical housing can be selected; if the electrode assembly 10 has a rectangular parallelepiped structure, a rectangular parallelepiped housing can be selected.

[0130] Exemplarily, the housing 20 includes a sidewall 22 and a bottom wall 23. The sidewall 22 surrounds the outside of the electrode assembly 10, and the bottom wall 23 is connected to the end of the sidewall 22. The sidewall 22 has a cylindrical structure, for example, a circular cylinder or a square cylinder; the bottom wall 23 has a plate-like structure, and its shape corresponds to the shape of the sidewall 22. Optionally, one end of the sidewall 22 forms an opening 21, and the bottom wall 23 is connected to the other end of the sidewall 22 facing away from the opening 21.

[0131] The sidewall 22 and the bottom wall 23 can be an integrally formed structure, that is, the housing 20 is an integrally formed component. Of course, the sidewall 22 and the bottom wall 23 can also be two components provided separately, and then connected together by welding, riveting, bonding, etc.

[0132] The end cap 30 can be electrically connected to the electrode assembly 10 or insulated from the electrode assembly 10. Optionally, the end cap 30 is electrically connected to the first electrode tab 11. Of course, the end cap 30 can be directly electrically connected to the first electrode tab 11 or can be electrically connected to the first electrode tab 11 through other conductive components.

[0133] The end cap 30 is fixedly connected to the housing 20. For example, the end cap 30 can be connected to the housing 20 by welding, clamping, bonding, or other means to fix the end cap 30 to the housing 20. The end cap 30 can be electrically connected to the housing 20 or insulated.

[0134] The housing 20 may be positively charged, negatively charged, or uncharged. When the housing 20 needs to be charged, the housing 20 may be directly connected to the tab of the electrode assembly 10 or electrically connected to the tab through other conductive components (such as the end cap 30).

[0135] The end cap 30 and the housing 20 can be connected by welding, so that the end cap 30 and the housing 20 have the same polarity. For example, when the housing 20 needs to be positively charged, the end cap 30 can be used to electrically connect the housing 20 to the positive polarity tab; when the housing 20 needs to be negatively charged, the end cap 30 can be used to electrically connect the housing 20 to the negative polarity tab. Of course, the housing 20 can also be connected to the tab via other conductive structures, and this embodiment is not limited to this.

[0136] The housing 20 and the end cover 30 may be made of the same material or different materials.

[0137] The strength of the weak portion 32 is relatively weak compared to the strength of other portions of the end cap 30. The weak portion 32 is a portion of the end cap 30 that is easily broken, shattered, torn, or opened. In this embodiment, the weak portion 32 can be formed by thinning a predetermined region of the end cap 30, performing a material treatment on the predetermined region of the end cap 30, performing a heat treatment on the predetermined region of the end cap 30, or forming the weak portion 32 in the predetermined region of the end cap 30 by other means.

[0138] The weak portion 32 extends along the circumference of the first connecting portion 31 and is connected to the edge of the first connecting portion 31. For example, the weak portion 32 may surround the first connecting portion 31 once, or only surround 1 / 2, 2 / 3, or 3 / 4 of the first connecting portion, which is not limited in this embodiment.

[0139] The fixing structure 60 may directly fix the first connection portion 31 to the first electrode tab 11 , or may indirectly fix the first connection portion 31 to the first electrode tab 11 through other components.

[0140] The fixing structure 60 may be a welding portion formed by welding, an adhesive layer formed by curing an adhesive, or other structures as long as it can achieve a fixed connection between the first electrode tab 11 and the first connecting portion 31 .

[0141] The fixing structure 60 may be a conductive structure to electrically connect the first connection portion 31 to the first electrode tab 11 . Alternatively, the fixing structure 60 may be an insulating structure to insulate the first connection portion 31 from the first electrode tab 11 .

[0142] The strength of the fixing structure 60 can be set as needed. When the internal pressure of the battery cell 7 reaches a threshold, the fixing structure 60 can be destroyed by the internal pressure, thereby disconnecting the first connection portion 31 from the first tab 11. Of course, the fixing structure 60 can also have a greater strength so that the fixing structure 60 can maintain the connection between the first connection portion 31 and the first tab 11 when the internal pressure of the battery cell 7 reaches a threshold.

[0143] During transportation, temperature fluctuations, or charging and discharging, the internal pressure of battery cells fluctuates alternately, causing the end cap to deform, either bulging away from the electrode assembly or concaving toward it. When the end cap alternates between bulging and concaving, the weak portion of the end cap is subjected to alternating stresses, causing alternating fatigue aging or fracture, which reduces the strength of the weak portion. This can easily cause the weak portion to rupture and release the internal pressure of the battery cell before the internal pressure reaches the preset threshold, leading to premature rupture and pressure release of the end cap.

[0144] In the embodiment of the present application, the first connection portion 31 of the end cover 30 is fixedly connected to the first pole ear 11 of the electrode assembly 10 through the fixing structure 60. In this way, the first pole ear 11 of the electrode assembly 10 can limit the movement of the first connection portion 31 during the use of the battery cell 7, thereby reducing the deformation and flipping of the end cover 30, reducing the alternating stress borne by the weak portion 32, slowing down the fatigue aging of the weak portion 32 of the end cover 30, and reducing the risk of premature rupture and pressure release of the end cover 30 under normal use of the battery cell 7, which is beneficial to improving the safety and stability of the battery cell 7.

[0145] In some embodiments, the end cap 30 is an integrally formed structure.

[0146] In some embodiments, the weak portion 32 surrounds the first connecting portion 31 .

[0147] The weak portion 32 is an annular structure surrounding the outside of the first connecting portion 31, and its shape corresponds to the outline of the first connecting portion 31. The first connecting portion 31 is located within the area enclosed by the weak portion 32. Optionally, the area enclosed by the weak portion 32 can be circular, rectangular, racetrack-shaped, or elliptical.

[0148] The weak portion 32 of this embodiment surrounds the first connecting portion 31 , which can increase the range of the weak portion 32 , increase the exhaust rate when the weak portion 32 ruptures, and improve safety.

[0149] In some embodiments, the first connection portion 31 is electrically connected to the first tab 11 through a fixing structure 60 .

[0150] The fixing structure 60 is conductive and can achieve electrical connection between the end cover 30 and the first electrode tab 11 .

[0151] In this embodiment, the end cap 30 can be charged and can serve as the output electrode of the battery cell 7 , thereby eliminating a traditional electrode terminal and simplifying the structure of the battery cell 7 .

[0152] In some embodiments, the end cap 30 is used to electrically connect the first tab 11 to the housing 20 .

[0153] In this embodiment, the housing 20 itself can serve as the output terminal of the battery cell 7. When multiple battery cells 7 are assembled into a group, the housing 20 can be electrically connected to the confluence component, which can not only increase the flow area but also make the structural design of the confluence component more flexible.

[0154] In some embodiments, the housing 20 further includes a sidewall 22 and a bottom wall 23 connected to the sidewall 22. The sidewall 22 extends along the thickness direction Z of the end cap 30 and surrounds the periphery of the electrode assembly 10. The bottom wall 23 defines an electrode lead-out hole 231. The electrode assembly 10 further includes a second electrode tab 13 having an opposite polarity to the first electrode tab 11. The second electrode tab 13 is disposed at an end of the electrode assembly 10 facing away from the outlet 21. The battery cell 7 further includes an electrode terminal 40 mounted in the electrode lead-out hole 231. The electrode terminal 40 is electrically connected to the second electrode tab 13.

[0155] The second electrode tab 13 may be directly electrically connected to the electrode terminal 40 , or may be indirectly electrically connected to the electrode terminal 40 through other conductive structures.

[0156] The electrode terminal 40 is insulated and disposed on the bottom wall 23 . The electrode terminal 40 and the bottom wall 23 may have different polarities. The electrode terminal 40 and the bottom wall 23 may serve as two output poles of the battery cell 7 , respectively.

[0157] When the first tab 11 is a negative tab and the second tab 13 is a positive tab, the bottom wall 23 is the negative output pole of the battery cell 7, and the electrode terminal 40 is the positive output pole of the battery cell 7. When the first tab 11 is a positive tab and the second tab 13 is a negative tab, the bottom wall 23 is the positive output pole of the battery cell 7, and the electrode terminal 40 is the negative output pole of the battery cell 7.

[0158] The electrode terminal 40 is fixed to the bottom wall 23. The electrode terminal 40 can be fixed as a whole to the outside of the bottom wall 23, or can extend into the interior of the housing 20 through the electrode lead-out hole 231.

[0159] The first electrode tab 11 is located at the end of the electrode assembly 10 facing the end cap 30, so as to facilitate electrical connection between the end cap 30 and the first electrode tab 11. Correspondingly, the second electrode tab 13 is located at the end of the electrode assembly 10 facing the bottom wall 23, so as to facilitate electrical connection between the electrode terminal 40 and the second electrode tab 13. In the embodiment of the present application, the first electrode tab 11 and the second electrode tab 13 are arranged at both ends of the electrode assembly 10, which can reduce the risk of electrical conduction between the first electrode tab 11 and the second electrode tab 13 and increase the flow area of ​​the first electrode tab 11 and the flow area of ​​the second electrode tab 13.

[0160] In this embodiment, the bottom wall 23 and the electrode terminal 40 can serve as the two output poles of the battery cell 7, which can simplify the structure of the battery cell 7 and ensure the current carrying capacity of the battery cell 7. The bottom wall 23 and the electrode terminal 40 are located at the same end of the battery cell 7. Therefore, when multiple battery cells 7 are assembled into a group, the current collecting component can be assembled to the same side of the battery cells 7, which can simplify the assembly process and improve assembly efficiency.

[0161] In some embodiments, the bottom wall 23 and the side wall 22 are integrally formed. This embodiment can omit the process of connecting the bottom wall 23 and the side wall 22. The housing 20 can be formed by a stretching process.

[0162] The electrode lead-out hole 231 in the embodiment of the present application is formed after the shell 20 is stretched.

[0163] The inventors have tried to roll the open end of the shell so that the open end of the shell is folded inward and forms a flange structure. The flange structure presses the end cover to fix the end cover. The inventors installed the electrode terminal on the end cover and used the flange structure and electrode terminal as the two output poles of the battery cell. However, the larger the size of the flange structure, the higher the risk of curling and wrinkling after forming; if the flange structure curls and wrinkles, it will cause the surface of the flange structure to be uneven, and when the flange structure is welded to the collector component, there will be problems with poor welding. Therefore, the size of the flange structure is relatively limited, resulting in insufficient current capacity of the battery cell.

[0164] In this embodiment, an electrode lead-out hole 231 for mounting the electrode terminal 40 is formed on the bottom wall 23 by a perforation process, thereby positioning the positive and negative output electrodes at the end of the battery cell 7 facing away from the outlet 21. The bottom wall 23 is formed during the molding process of the housing 20. The electrode lead-out hole 231 ensures the flatness of the bottom wall 23 and the connection strength between the bottom wall 23 and the current collector. Furthermore, the flatness of the bottom wall 23 is not constrained by its own dimensions, allowing it to be larger, thereby improving the current handling capacity of the battery cell 7.

[0165] In some embodiments, the first electrode tab 11 is a negative electrode tab, and the base material of the shell 20 is steel.

[0166] The housing 20 is electrically connected to the negative electrode tab, that is, the housing 20 is in a low potential state. The steel housing 20 is not easily corroded by the electrolyte in the low potential state, thereby reducing safety risks.

[0167] In some embodiments, the housing 20 is welded to the end cap 30. Welding can not only achieve the connection between the housing 20 and the end cap 30, improve the flow capacity between the housing 20 and the end cap 30, but also ensure the sealing.

[0168] In some embodiments, the base material of the housing 20 is the same as the base material of the end cover 30. Optionally, the base material of the housing 20 and the base material of the end cover 30 are both steel.

[0169] In this embodiment, the base material of the housing 20 and the base material of the end cover 30 are the same, which can ensure the welding strength between the housing 20 and the end cover 30 and the sealing of the battery cell 7.

[0170] In some embodiments, the battery cell 7 is a cylindrical battery cell. Correspondingly, the electrode assembly 10 is a cylindrical structure, and the housing 20 is a cylindrical hollow structure.

[0171] In some embodiments, the fixing structure 60 is configured to be at least partially destroyed when the internal pressure of the battery cell 7 reaches a threshold value to disconnect the first connecting portion 31 from the first tab 11 .

[0172] When a battery cell 7 experiences thermal runaway, the electrode assembly 10 generates high-temperature, high-pressure gas, and the internal pressure of the battery cell 7 increases as the gas builds up. The end cap 30 deforms under the action of the gas pressure, exerting a tensile force on the fixing structure 60. When the internal pressure of the battery cell 7 reaches a threshold, the end cap 30, under the action of the gas pressure, breaks the fixing structure 60, severing the fixed connection between the first connecting portion 31 and the first electrode tab 11.

[0173] This embodiment does not limit the order of rupturing the fixing structure 60 and the weak portion 32 , as long as both the fixing structure 60 and the weak portion 32 can be ruptured when the internal pressure of the battery cell 7 reaches the threshold.

[0174] In this embodiment, after the connection between the first connecting portion 31 and the first electrode tab 11 is disconnected, the first electrode tab 11 will no longer restrict the movement of the first connecting portion 31; as the weak portion 32 ruptures, the first connecting portion 31 can be opened by air pressure to increase the channel for releasing internal pressure, thereby quickly releasing internal pressure and improving safety.

[0175] Illustratively, the weakened portion 32 surrounds the first connecting portion 31 once; after the weakened portion 32 ruptures, the first connecting portion 31 is disconnected from the rest of the end cap 30. Thus, the first connecting portion 31 is forced open and detached from the battery cell 7 under the action of air pressure. Alternatively, the weakened portion 32 may surround the first connecting portion 31 for less than a full circle. After the weakened portion 32 ruptures, the first connecting portion 31 remains connected to the rest of the end cap 30; however, under the action of air pressure, the first connecting portion 31 flips outward to increase the channel for relieving internal pressure.

[0176] In some embodiments, the battery cell 7 further includes a current collecting member 50 disposed between the end cap 30 and the first electrode tab 11. The current collecting member 50 is used to connect the first connecting portion 31 and the first electrode tab 11 to achieve electrical connection between the end cap 30 and the first electrode tab 11. The fixing structure 60 includes a first fixing structure 61 and a second fixing structure 62. The first fixing structure 61 is a welded portion formed by welding a portion of the current collecting member 50 to the first electrode tab 11, and the second fixing structure 62 is a welded portion formed by welding another portion of the current collecting member 50 to the first connecting portion 31.

[0177] A portion of the current collecting member 50 is welded to the first electrode tab 11 to achieve electrical connection therebetween. Another portion of the current collecting member 50 is welded to the first connecting portion 31 to achieve electrical connection therebetween.

[0178] In addition to a portion welded to the first electrode tab 11 and another portion welded to the first connection portion 31 , the current collecting member 50 may further include other portions.

[0179] After research, the inventors found that the end surface of the first electrode tab 11 facing the end cover 30 is uneven and difficult to fit tightly with the first connecting portion 31. If the first connecting portion 31 and the first electrode tab 11 are directly welded, microcracks may occur in the first connecting portion 31, causing the risk of sealing failure of the end cover 30, posing a safety hazard.

[0180] In this embodiment, the current collecting component 50 is an independently formed component, which is different from the first electrode tab 11 formed by winding. The shape of the current collecting component 50 can be adaptively adjusted according to the shape of the end cover 30 to ensure that the current collecting component 50 can be tightly attached to the first connecting portion 31 of the end cover 30.

[0181] In this embodiment, a current collecting member 50 is provided in the battery cell 7 and welded to the first connecting portion 31 and the first electrode tab 11, respectively, to achieve electrical connection between the end cap 30 and the first electrode tab 11. The current collecting member 50 is tightly fitted to the first connecting portion 31, reducing the risk of microcracks in the first connecting portion 31, improving sealing performance, and mitigating safety hazards. Even if microcracks develop in the current collecting member 50 during welding to the first electrode tab 11, this will not affect the sealing of the battery cell 7.

[0182] In this embodiment, the first fixing structure 61 and the second fixing structure 62 can fix the first connection portion 31 , the current collecting member 50 and the first electrode tab 11 to restrict movement of the first connection portion 31 .

[0183] In some embodiments, the current collecting component 50 includes a first current collecting part 51 and a second current collecting part 52, the first current collecting part 51 surrounds the outside of the second current collecting part 52, the first fixed structure 61 is a welding part formed by welding the first current collecting part 51 and the first pole ear 11, and the second fixed structure 62 is a welding part formed by welding the second current collecting part 52 and the first connecting part 31.

[0184] The first current collecting portion 51 is an annular structure surrounding the second current collecting portion 52. Optionally, the portion of the current collecting member 50 that contacts the first connection portion 31 is the second current collecting portion 52, and the portion of the current collecting member 50 that does not contact the first connection portion 31 is the first current collecting portion 51.

[0185] The first fixing structure 61 is located outside the second fixing structure 62 , that is, the first fixing structure 61 is closer to the side wall 22 of the housing 20 than the second fixing structure 62 .

[0186] The first fixing structure 61 and the second fixing structure 62 are structures formed after the material undergoes processes such as melting, cooling and solidification, and the surfaces of the two are uneven.

[0187] When assembling the battery cell 7, the current collecting member 50 is first pressed against and welded to the first electrode tab 11 to form the first fixing structure 61. The first connecting portion 31 and the current collecting member 50 are then welded to form the second fixing structure 62. If the second fixing structure 62 overlaps with the first fixing structure 61 along the thickness direction Z of the end cap 30, the portion of the first connecting portion 31 intended for welding to the current collecting member 50 will need to press against the first fixing structure 61 when welding the first connecting portion 31 to the current collecting member 50. Due to the uneven surface of the first fixing structure 61, if the portion of the first connecting portion 31 intended for welding to the current collecting member 50 presses against the first fixing structure 61, it will be difficult for the first connecting portion 31 to fit tightly against the first fixing structure 61. This can result in poor welding, compromise the connection strength between the first connecting portion 31 and the current collecting member 50, and increase the risk of microcracks forming in the first connecting portion 31.

[0188] In this embodiment, the first fixing structure 61 and the second fixing structure 62 are respectively formed on the first collecting part 51 and the second collecting part 52, so as to avoid the first fixing structure 61 affecting the welding of the first connecting part 31 and the current collecting component 50, thereby improving the connection strength between the first connecting part 31 and the current collecting component 50.

[0189] In some embodiments, the second fixing structure 62 is configured to be broken when the internal pressure of the battery cell 7 reaches a threshold value to disconnect the second current collecting portion 52 from the first connecting portion 31 .

[0190] When a battery cell 7 experiences thermal runaway, the electrode assembly 10 generates high-temperature, high-pressure gas, and the internal pressure of the battery cell 7 increases as the gas builds up. The gas pressure deforms the end cap 30, exerting a tensile force on the second fixing structure 62. When the internal pressure of the battery cell 7 reaches a threshold, the gas pressure from the end cap 30 breaks the second fixing structure 62, severing the fixed connection between the first connector 31 and the second current collector 52.

[0191] After the connection between the first connecting portion 31 and the second current collecting portion 52 is disconnected, the first electrode tab 11 will no longer restrict the movement of the first connecting portion 31 through the current collecting component 50; as the weak portion 32 ruptures, the first connecting portion 31 can be opened by air pressure to increase the channel for releasing internal pressure, thereby quickly releasing internal pressure and improving safety.

[0192] In some embodiments, when the internal pressure of the battery cell 7 reaches a threshold, the first fixing structure 61 maintains the connection between the first electrode tab 11 and the first current collecting portion 51 to fix the current collecting member 50 and reduce the risk of the current collecting member 50 blocking the channel for releasing internal pressure.

[0193] In some embodiments, the connection strength between the second current collecting portion 52 and the first connecting portion 31 is smaller than the connection strength between the first current collecting portion 51 and the first electrode tab 11 .

[0194] The connection strength between the second current collecting portion 52 and the first connecting portion 31 can be characterized by the tensile strength of the second fixing structure 62, while the connection strength between the first current collecting portion 51 and the first electrode tab 11 can be characterized by the tensile strength of the first fixing structure 61. The tensile strengths of the first fixing structure 61 and the second fixing structure 62 can be tested using a tensile testing machine. For example, the electrode assembly 10 can be fixed to a fixture, and the tensile testing machine can be used to pull the current collecting member 50 to break the first fixing structure 61 and separate the first electrode tab 11 and the current collecting member 50 of the electrode assembly 10. The tensile strength of the first fixing structure 61 can be calculated based on the measured data. The tensile strength of the second fixing structure 62 can be measured in the same manner.

[0195] When thermal runaway occurs in the battery cell 7, the end cover 30 applies a pulling force to the current collecting member 50 and the first pole tab 11 under the action of air pressure; since the connection strength between the second current collecting part 52 and the first connecting part 31 is less than the connection strength between the first current collecting part 51 and the first pole tab 11, the current collecting member 50 will first separate from the first connecting part 31; after the current collecting member 50 is separated from the first connecting part 31, the current collecting member 50 will not be subjected to the pulling force of the end cover 30, thereby maintaining the fixed connection between the current collecting member 50 and the first pole tab 11, reducing the risk of the current collecting member 50 blocking the channel for releasing internal pressure.

[0196] In some embodiments, the first connection portion 31 includes a first protrusion 311 and a first plate 312 surrounding the outer side of the first protrusion 311. The first protrusion 311 protrudes from the inner surface of the first plate 312 in a direction facing the electrode assembly 10. A first recess 313 is formed on the first connection portion 31 at a position corresponding to the first protrusion 311, which is recessed from the outer surface of the first plate 312 in a direction facing the electrode assembly 10. The weak portion 32 is located on the outer side of the first plate 312 and is provided along the outer edge of the first plate 312. The second current collecting portion 52 abuts against and is welded to the first protrusion 311 to form a second fixing structure 62.

[0197] The first plate 312 may be an annular flat plate structure having an inner surface and an outer surface oppositely disposed along the thickness direction Z. The inner surface of the first plate 312 faces the electrode assembly 10. The first protrusion 311 protrudes from the weak portion 32 in a direction facing the electrode assembly 10.

[0198] The first recess 313 can reduce the strength of the first protrusion 311 and increase its elasticity. Thus, when the battery cell 7 vibrates, the first protrusion 311 can release stress through deformation, reducing the stress transferred to the weak portion 32 and slowing down fatigue aging of the weak portion 32. The first recess 313 can also reduce the thickness of the first protrusion 311, reducing the energy required to weld the first protrusion 311 to the second current collecting portion 52, reducing the heat transferred to the weak portion 32, and slowing down fatigue aging of the weak portion 32.

[0199] In some embodiments, the first collecting portion 51 covers the weak portion 32 in the thickness direction Z of the end cover 30 .

[0200] The projection of the weak portion 32 along the thickness direction Z is located within the projection of the first current collecting portion 51 along the thickness direction Z.

[0201] In this embodiment, the current collecting member 50 can separate the weak portion 32 from the first electrode tab 11 to reduce active particles in the electrode assembly 10 falling onto the weak portion 32 and reduce the risk of corrosion of the weak portion 32 .

[0202] In some embodiments, the first protrusion 311 supports the current collecting member 50 to form an escape gap G between the first current collecting member 51 and the end cover 30 for escaping the weak portion 32 .

[0203] The escape gap G is a space formed between the first header 51 and the end cover 30 and not filled with other solid components. The escape gap G is opposite to the weak portion 32 along the thickness direction Z, thereby playing a role in escaping the weak portion 32.

[0204] The first connection portion 31 supports the first electrode tab 11 via the current collecting member 50, thereby reducing the shaking amplitude of the electrode assembly 10 when the battery cell 7 vibrates, thereby improving the stability of the electrode assembly 10. The avoidance gap G separates the weak portion 32 from the first current collecting portion 51, preventing the first current collecting portion 51 from blocking the channel for relieving internal pressure when the weak portion 32 ruptures, thereby improving safety.

[0205] In some embodiments, the electrode assembly 10 is a wound structure having a first through-hole 14 at the center of the winding. The second current collecting portion 52 is provided with a second through-hole 521, which is arranged opposite to the first through-hole 14 to guide the gas in the electrode assembly 10 to the first connecting portion 31.

[0206] In the thickness direction Z, the first through hole 14 and the second through hole 521 at least partially overlap, so that the first through hole 14 and the second through hole 521 are communicated.

[0207] When the electrode assembly 10 thermally runs away, high-temperature and high-pressure gas can act on the first connection portion 31 through the first through-holes 14 and the second through-holes 521 , thereby quickly disconnecting the first connection portion 31 and the current collecting member 50 .

[0208] In some embodiments, the end cap 30 further includes a second connecting portion 33, which surrounds the outside of the first connecting portion 31 and is used to be fixedly connected to the housing 20. The weak portion 32 is located between the first connecting portion 31 and the second connecting portion 33 and is used to connect the first connecting portion 31 and the second connecting portion 33.

[0209] The second connection portion 33 can be connected to the housing 20 by welding, clamping, bonding or other means to fix the end cover 30 to the housing 20. The second connection portion 33 can be electrically connected to the housing 20 or insulated.

[0210] The strength of the second connection portion 33 is greater than the strength of the weak portion 32 ; illustratively, the thickness of the second connection portion 33 is greater than the thickness of the weak portion 32 .

[0211] In this embodiment, the end cover 30 is fixed to the shell 20 by a second connecting portion 33 surrounding the outside of the weak portion 32 to increase the distance between the weak portion 32 and the shell 20, reduce the stress transmitted to the weak portion 32, and slow down fatigue aging of the weak portion 32.

[0212] In some embodiments, the weak portion 32 is configured to rupture and disconnect the first connection portion 31 and the second connection portion 33 when the internal pressure of the battery cell 7 reaches a threshold value.

[0213] In this embodiment, after the connection between the first connection part 31 and the second connection part 33 is disconnected, the first connection part 31 and the second connection part 33 can be flipped outward under the action of internal pressure to increase the channel for releasing the internal pressure, thereby quickly releasing the internal pressure and improving safety.

[0214] Illustratively, the end cap 30 electrically connects the housing 20 to the first electrode tab 11, and the housing 20 serves as the output terminal of the battery cell 7. When the internal pressure of the battery cell 7 reaches a threshold, the weak portion 32 ruptures and disconnects the first connecting portion 31 and the second connecting portion 33. This disconnects the electrode assembly 10 from the external circuit, halting charging and discharging, slowing gas production in the electrode assembly 10, and improving safety.

[0215] Exemplarily, the fixing structure 60 is configured to be at least partially destroyed when the internal pressure of the battery cell 7 reaches a threshold value, thereby disconnecting the first connection portion 31 from the first tab 11. Simultaneously, as the weak portion 32 ruptures, the first connection portion 31 detaches from the second connection portion 33 under the action of gas pressure, thereby increasing the channel for relieving internal pressure, thereby rapidly relieving internal pressure and improving safety.

[0216] In some embodiments, the second connection portion 33 includes a second plate body 332 and a second protrusion 331 surrounding the outside of the second plate body 332. The second protrusion 331 protrudes from the inner surface of the second plate body 332 in a direction facing the electrode assembly 10. A second recess 333 is formed on the second connection portion 33 at a position corresponding to the second protrusion 331, which is recessed from the outer surface of the second plate body 332 in a direction facing the electrode assembly 10. The second plate body 332 surrounds the outside of the weak portion 32, and the second protrusion 331 is used to securely connect to the housing 20.

[0217] The second plate body 332 may be an annular flat plate structure having an inner surface and an outer surface oppositely disposed along the thickness direction Z. The inner surface of the second plate body 332 faces the electrode assembly 10 .

[0218] The second protrusion 331 protrudes from the weak portion 32 in a direction facing the electrode assembly 10 .

[0219] Optionally, the second plate body 332 and the current collecting member 50 at least partially overlap in the thickness direction Z.

[0220] The second concave portion 333 can reduce the strength of the second convex portion 331 and improve the elasticity of the second convex portion 331. In this way, when the battery cell 7 vibrates, the stress on the shell 20 is transferred to the second convex portion 331. The second convex portion 331 can release the stress by deformation to reduce the stress transferred to the weak portion 32 and slow down the fatigue aging of the weak portion 32.

[0221] Exemplarily, the weak portion 32 is located between the first plate 312 and the second plate 332 and connects the first plate 312 and the second plate 332 .

[0222] In some embodiments, the outer side surface 331 a of the second protrusion 331 abuts against the inner surface of the housing 20 and is used for welding with the housing 20 to close the opening 21 .

[0223] The outer side surface 331a of the second protrusion 331 is a surface of the second protrusion 331 facing the side wall 22 of the housing 20. The outer side surface 331a of the second protrusion 331 is a cylindrical surface. Optionally, the outer side surface 331a of the second protrusion 331 is a cylindrical surface.

[0224] The portion of the second protrusion 331 extending into the housing 20 may have an interference fit, a transition fit, or a clearance fit with the housing 20. Optionally, the portion of the second protrusion 331 extending into the housing 20 may have an interference fit with the housing 20. The interference fit may increase the connection strength between the housing 20 and the end cover 30 and improve the sealing performance.

[0225] Optionally, the second protrusion 331 and the sidewall 22 of the housing 20 are connected by laser welding. During welding, a laser is irradiated at the junction of the second protrusion 331 and the sidewall 22, melting and connecting at least a portion of the outer side surface 331a of the second protrusion 331 and a portion of the inner surface of the housing 20. The outer side surface 331a of the second protrusion 331 abuts the inner surface of the housing 20, thereby reducing the risk of laser light entering the interior of the housing 20 and burning the electrode assembly 10.

[0226] Alternatively, the laser may also be irradiated onto the outer surface of the side wall 22 facing away from the second protrusion 331 .

[0227] In this embodiment, welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and flow capacity between the second protrusion 331 and the housing 20.

[0228] The second recess 333 can reduce the strength of the second protrusion 331 and improve the elasticity of the second protrusion 331. In this way, during the welding process of the second protrusion 331 and the shell 20, the second protrusion 331 can release the welding stress through deformation, thereby reducing the risk of deformation and cracking in the welding area, reducing the welding stress transmitted to the weak part 32, and improving safety.

[0229] In some embodiments, the second protrusion 331 abuts against the first electrode tab 11 to support the first electrode tab 11 .

[0230] In this embodiment, the second protrusion 331 supports the first electrode tab 11 to reduce the shaking amplitude of the electrode assembly 10 when the battery cell 7 vibrates, thereby improving the stability of the electrode assembly 10 .

[0231] The current collecting member 50 supports the middle area of ​​the first electrode tab 11, and the second protrusion 331 supports the edge area of ​​the first electrode tab 11. This can improve the uniformity of the force applied to the first electrode tab 11 and reduce the risk of the electrode sheet of the electrode assembly 10 being offset or misaligned in the thickness direction Z.

[0232] When the first connection portion 31 is separated from the battery cell 7 under the action of air pressure, the second protrusion 331 can support the first electrode 11 and the current collecting member 50 to reduce the risk of the current collecting member 50 blocking the channel for releasing internal pressure, thereby ensuring smooth exhaust and improving safety.

[0233] Figure 7 for Figure 4A partial cross-sectional schematic diagram of the end cover is shown.

[0234] like Figure 7 As shown, in some embodiments, the end cap 30 is provided with a groove 34 , and a region of the end cap 30 opposite to the groove 34 forms a weak portion 32 .

[0235] The thickness of the weak portion 32 is smaller than that of the first connecting portion, so that the strength of the weak portion 32 is smaller than that of the first connecting portion.

[0236] For example, machining can be used to remove material from the end cap 30 to form the groove 34, which helps reduce processing costs and difficulty. Along the thickness direction of the end cap 30, the weak portion 32 and the groove 34 are correspondingly arranged.

[0237] The groove 34 may be provided on the inner surface of the end cap 30, and the weak portion 32 is the portion of the end cap 30 located between the bottom surface of the groove 34 and the outer surface of the end cap 30. Alternatively, the groove 34 may also be provided on the outer surface of the end cap 30, and the weak portion 32 is the portion of the end cap 30 located between the bottom surface of the groove 34 and the inner surface of the end cap 30.

[0238] Exemplarily, the inner surface of the end cap 30 includes the inner surface of the first plate 312 and the inner surface of the second plate 332, and the outer surface of the end cap 30 includes the outer surface of the first plate 312 and the outer surface of the second plate 332. The inner surface of the first plate 312 and the inner surface of the second plate 332 are flush, and the outer surface of the first plate 312 and the outer surface of the second plate 332 are flush. The groove 34 is located between the first plate 312 and the second plate 332.

[0239] In this embodiment, the groove 34 is provided to reduce the thickness and strength of the weak portion 32 , so that the end cover 30 can be broken along the weak portion 32 when the internal pressure of the battery cell 7 reaches a threshold.

[0240] In some embodiments, the end cap 30 includes a first nickel layer 30a, a steel layer 30b, and a second nickel layer 30c. The first nickel layer 30a is disposed on a surface of the steel layer 30b facing the first tab, and the second nickel layer 30c is disposed on a surface of the steel layer 30b facing away from the first tab. A groove 34 is recessed from the surface of the first nickel layer 30a facing away from the steel layer 30b toward the second nickel layer 30c, and the depth of the groove 34 is greater than the thickness of the first nickel layer 30a and less than the sum of the thicknesses of the first nickel layer 30a and the steel layer 30b.

[0241] The surface of the first nickel layer 30 a facing away from the steel layer 30 b is the inner surface of the end cover 30 , and the surface of the second nickel layer 30 c facing away from the steel layer 30 b is the outer surface of the end cover 30 .

[0242] The end cap 30 is made of a metal composite plate. The first nickel layer 30a and the second nickel layer 30c can protect the steel layer 30b, reduce the risk of the steel layer 30b being corroded by substances such as water and oxygen, and improve the sealing performance.

[0243] The thickness of the first nickel layer 30a and the thickness of the second nickel layer 30c are both smaller than the thickness of the steel layer 30b.

[0244] The first nickel layer 30a and the second nickel layer 30c mainly play a role in corrosion resistance and can have a relatively small thickness; while the steel layer 30b is the base structure of the end cover 30 and can have a relatively large thickness.

[0245] In this embodiment, the groove 34 is located on the inner side of the end cover 30 and will not damage the external second nickel layer 30c during the molding process. Therefore, the second nickel layer 30c can protect the steel layer 30b from the outside to reduce the risk of corrosion of the steel layer 30b. The steel layer 30b itself is not easily corroded by the electrolyte. Therefore, even if the groove 34 exposes the steel layer 30b, it is not likely to cause safety risks.

[0246] Figure 8 Schematic cross-sectional views of battery cells provided in some other embodiments of the present application; Figure 9 for Figure 8 An enlarged schematic diagram of a battery cell at box B is shown.

[0247] like Figure 8 and Figure 9 As shown, in some embodiments, the fixing structure 60 is a welding portion formed by welding the first electrode tab 11 and the first connecting portion 31 .

[0248] In this embodiment, the first connecting portion 31 is directly connected to the first electrode tab 11 by welding, which can simplify the structure of the battery cell 7 . For example, the current collecting component can be omitted.

[0249] Figure 10 A schematic flow chart of a method for manufacturing a battery cell provided in some embodiments of the present application.

[0250] like Figure 10 As shown, the manufacturing method of the battery cell of the embodiment of the present application includes:

[0251] S100, providing a housing, wherein the housing has an opening;

[0252] S200, providing an electrode assembly and installing the electrode assembly into a housing, wherein the electrode assembly is provided with a first electrode tab at one end facing the opening;

[0253] S300, providing an end cover, and connecting the end cover to the housing so that the end cover covers the opening, the end cover comprising a first connecting portion and a weakened portion, wherein the weakened portion is provided along an edge of the first connecting portion;

[0254] S400, fixing the first connecting portion to the first electrode tab to form a fixed structure to limit movement of the first connecting portion;

[0255] The end cap is configured to rupture along a weak portion when the internal pressure of the battery cell reaches a threshold value to release the internal pressure.

[0256] It should be noted that the relevant structure of the battery cell manufactured by the above-mentioned method for manufacturing the battery cell can refer to the battery cells provided in the above-mentioned embodiments.

[0257] Figure 11 A schematic block diagram of a battery cell manufacturing system provided in some embodiments of the present application.

[0258] like Figure 11 As shown, the battery cell manufacturing system 90 of the embodiment of the present application includes:

[0259] A first providing device 91 is used to provide a housing having an opening;

[0260] A second providing device 92 is used to provide an electrode assembly and install the electrode assembly into the housing, wherein the electrode assembly is provided with a first electrode tab at one end facing the opening;

[0261] A third providing device 93 is used to provide an end cap and connect the end cap to the housing so that the end cap covers the opening, the end cap including a first connecting portion and a weakened portion, the weakened portion being provided along an edge of the first connecting portion;

[0262] An assembly device 94 is used to fix the first connecting portion to the first tab and form a fixed structure to limit the movement of the first connecting portion;

[0263] The end cap is configured to rupture along a weak portion when the internal pressure of the battery cell reaches a threshold value to release the internal pressure.

[0264] The relevant structure of the battery cells manufactured by the above manufacturing system can refer to the battery cells provided in the above embodiments.

[0265] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0266] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, characterized in that: include: a housing having an opening; an electrode assembly housed in the housing, the electrode assembly being provided with a first electrode tab at one end facing the opening, wherein the electrode assembly comprises a first electrode sheet, a second electrode sheet, and a separator, the separator being used to separate the first electrode sheet from the second electrode sheet; an end cover for covering the opening, the end cover comprising a first connecting portion and a weakened portion, the weakened portion being arranged along an edge of the first connecting portion, the end cover being configured to rupture along the weakened portion when the internal pressure of the battery cell reaches a threshold value to release the internal pressure; The battery cell further includes a fixing structure, wherein the fixing structure is used to fix the first connecting portion to the first tab to limit movement of the first connecting portion; The first connecting portion includes a first protrusion and a first plate surrounding the outside of the first protrusion, the first protrusion protruding from the inner surface of the first plate in a direction facing the electrode assembly, and a first recessed portion recessed from the outer surface of the first plate in a direction facing the electrode assembly is formed at a position on the first connecting portion corresponding to the first protrusion; The weak portion is located on the outside of the first plate body and is arranged along the outer edge of the first plate body.

2. The battery cell according to claim 1, wherein: The first connecting portion is electrically connected to the first tab through the fixing structure.

3. The battery cell according to claim 1, wherein: The fixing structure is configured to be at least partially destroyed when the internal pressure of the battery cell reaches the threshold value to disconnect the first connecting portion from the first tab.

4. The battery cell according to claim 1, wherein: The fixing structure is a welding portion formed by welding the first electrode tab and the first connecting portion.

5. The battery cell according to claim 1, characterized in that The device further comprises a current collecting member disposed between the end cover and the first electrode tab, wherein the current collecting member is used to connect the first connecting portion and the first electrode tab to achieve electrical connection between the end cover and the first electrode tab; The fixing structure includes a first fixing structure and a second fixing structure. The first fixing structure is a welding portion formed by welding a portion of the current collecting component to the first tab. The second fixing structure is a welding portion formed by welding another portion of the current collecting component to the first connecting portion.

6. The battery cell according to claim 5, characterized in that The current collecting component includes a first current collecting part and a second current collecting part, the first current collecting part surrounds the outside of the second current collecting part, the first fixing structure is a welding part formed by welding the first current collecting part and the first electrode tab, and the second fixing structure is a welding part formed by welding the second current collecting part and the first connecting part.

7. The battery cell according to claim 6, characterized in that The second fixing structure is configured to be broken when the internal pressure of the battery cell reaches the threshold value to disconnect the second current collecting portion from the first connecting portion.

8. The battery cell according to claim 6, characterized in that The connection strength between the second current collecting portion and the first connecting portion is smaller than the connection strength between the first current collecting portion and the first electrode tab.

9. The battery cell according to claim 6, characterized in that: The second collecting portion abuts against and is welded to the first protrusion to form the second fixing structure.

10. The battery cell according to claim 9, characterized in that The first collecting portion covers the weak portion in a thickness direction of the end cover.

11. The battery cell according to claim 9, characterized in that The first protrusion supports the current collecting member to form an escape gap between the first current collecting portion and the end cover for escaping the weak portion.

12. The battery cell according to claim 6, characterized in that The electrode assembly is a wound structure, and the electrode assembly has a first through hole at the center of the winding; The second current collecting portion is provided with a second through hole, and the second through hole is configured to be disposed opposite to the first through hole to guide the gas in the electrode assembly to the first connecting portion.

13. The battery cell according to any one of claims 1 to 12, characterized in that: The end cover further includes a second connecting portion, which surrounds the outside of the first connecting portion and is used to be fixedly connected to the housing; The weak portion is located between the first connecting portion and the second connecting portion and is used to connect the first connecting portion and the second connecting portion.

14. The battery cell according to claim 13, characterized in that The weak portion is configured to rupture and disconnect the first connection portion and the second connection portion when the internal pressure of the battery cell reaches the threshold value.

15. The battery cell according to claim 13, characterized in that The second connecting portion includes a second plate body and a second protrusion surrounding the outer side of the second plate body, the second protrusion protruding from the inner surface of the second plate body in a direction facing the electrode assembly, and a second recessed portion recessed from the outer surface of the second plate body in a direction facing the electrode assembly is formed at a position on the second connecting portion corresponding to the second protrusion; The second plate surrounds the outer side of the weak portion, and the second protrusion is used for fixed connection with the shell.

16. The battery cell according to claim 15, characterized in that The outer side surface of the second protrusion abuts against the inner surface of the shell and is used for welding with the shell to close the opening.

17. The battery cell according to claim 15, characterized in that The second protrusion abuts against the first electrode tab to support the first electrode tab.

18. The battery cell according to any one of claims 1 to 12, characterized in that: The weak portion surrounds the first connecting portion.

19. The battery cell according to any one of claims 1 to 12, characterized in that: The end cover is provided with a groove, and the area of ​​the end cover opposite to the groove forms the weak portion.

20. The battery cell according to claim 19, characterized in that The end cap comprises a first nickel layer, a steel layer, and a second nickel layer, wherein the first nickel layer is arranged on a surface of the steel layer facing the first electrode tab, and the second nickel layer is arranged on a surface of the steel layer facing away from the first electrode tab; The groove is recessed from the surface of the first nickel layer away from the steel layer in a direction facing the second nickel layer, and the depth of the groove is greater than the thickness of the first nickel layer and less than the sum of the thicknesses of the first nickel layer and the steel layer.

21. The battery cell according to any one of claims 1 to 12, characterized in that: The end cover is used to electrically connect the first tab to the housing.

22. The battery cell according to claim 21, characterized in that The housing further includes a side wall and a bottom wall connected to the side wall, wherein the side wall extends along the thickness direction of the end cover and is arranged around the outer periphery of the electrode assembly, and the bottom wall is provided with an electrode lead-out hole; The electrode assembly further includes a second electrode tab having a polarity opposite to that of the first electrode tab, wherein the second electrode tab is provided at an end of the electrode assembly away from the opening; The battery cell further includes an electrode terminal installed in the electrode lead-out hole, and the electrode terminal is electrically connected to the second electrode tab.

23. The battery cell according to claim 22, characterized in that The bottom wall and the side wall are integrally formed.

24. The battery cell according to claim 21, characterized in that The first electrode tab is a negative electrode tab, and the base material of the shell is steel.

25. The battery cell according to any one of claims 1 to 12, characterized in that: The battery cell is a cylindrical battery cell.

26. A battery, characterized in that: The method comprises a plurality of battery cells according to any one of claims 1 to 25.

27. An electrical device, characterized in that: The battery according to claim 26 is included for providing electrical energy.

28. A method for manufacturing a battery cell, characterized in that: include: providing a housing having an opening; Providing an electrode assembly and installing the electrode assembly into the housing, wherein the electrode assembly is provided with a first electrode tab at one end facing the opening, wherein the electrode assembly includes a first electrode piece, a second electrode piece, and a separator, wherein the separator is used to separate the first electrode piece from the second electrode piece; Providing an end cover, and connecting the end cover to the housing so that the end cover covers the opening, the end cover comprising a first connecting portion and a weakened portion, the weakened portion being arranged along an edge of the first connecting portion; The first connecting portion is fixedly connected to the first tab to form a fixed structure to limit movement of the first connecting portion; The first connecting portion includes a first protrusion and a first plate surrounding the outside of the first protrusion, the first protrusion protruding from the inner surface of the first plate in a direction facing the electrode assembly, and a first recessed portion recessed from the outer surface of the first plate in a direction facing the electrode assembly is formed at a position on the first connecting portion corresponding to the first protrusion; The weak portion is located on the outer side of the first plate body and is arranged along the outer edge of the first plate body; The end cover is configured to rupture along the weak portion when the internal pressure of the battery cell reaches a threshold value, so as to release the internal pressure.

29. A battery cell manufacturing system, characterized in that: include: A first providing device is used to provide a housing, wherein the housing has an opening; a second providing device, configured to provide an electrode assembly and install the electrode assembly into the housing, wherein the electrode assembly is provided with a first electrode tab at one end facing the opening, wherein the electrode assembly includes a first electrode sheet, a second electrode sheet, and a separator, wherein the separator is configured to separate the first electrode sheet from the second electrode sheet; A third providing device is used to provide an end cover and connect the end cover to the housing so that the end cover covers the opening, the end cover comprising a first connecting portion and a weakened portion, the weakened portion being provided along an edge of the first connecting portion; An assembly device, configured to fixedly connect the first connecting portion to the first tab to form a fixed structure, thereby limiting movement of the first connecting portion; The first connecting portion includes a first protrusion and a first plate surrounding the outside of the first protrusion, the first protrusion protruding from the inner surface of the first plate in a direction facing the electrode assembly, and a first recessed portion recessed from the outer surface of the first plate in a direction facing the electrode assembly is formed at a position on the first connecting portion corresponding to the first protrusion; The weak portion is located on the outer side of the first plate body and is arranged along the outer edge of the first plate body; The end cover is configured to rupture along the weak portion when the internal pressure of the battery cell reaches a threshold value, so as to release the internal pressure.

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