Battery cell, its manufacturing method and manufacturing system, battery, and power consumption device

Abstract

The present disclosure provides a battery cell, a manufacturing method and system therefor, a battery, and a power consumption device. The battery cell includes a housing having an opening, an electrode assembly housed in the housing and having a first tab at one end facing the opening, and an end cap used to cover the opening, including a first connection portion and a weakened portion along an edge of the first connection portion, configured to rupture along the weakened portion when internal pressure of the battery cell reaches a threshold value, thereby relieving the internal pressure. The battery cell further includes a fixing structure for fixedly connecting the first connection portion to the first tab to limit movement of the first connection portion. The present disclosure reduces the risk of premature rupture and relief of the end cap during normal use of the battery cell, contributing to improved safety and stability of the battery cell.

Description

[Technical Field]

[0001] This application relates to the field of battery technology, and more particularly to battery cells, methods and systems for manufacturing the same, batteries, and power consuming devices. [Background technology]

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

[0003] With the development of battery technology, in addition to improving the performance of battery cells, safety issues have also become a non-negligible issue. If the safety of a battery cell cannot be guaranteed, the battery cell cannot be used. Therefore, how to ensure the safety of battery cells has become a technical issue that needs to be resolved as soon as possible in battery technology. Summary of the Invention

[0004] The present application provides a battery cell that can improve the safety of the battery cell, a manufacturing method and manufacturing system thereof, a battery, and a power consuming device.

[0005] In a first aspect, embodiments of the present application provide a battery cell, the battery cell comprising: a housing having an opening; an electrode assembly housed within the housing and having a first tab on one end facing the opening; an end cap used to cover the opening, including a first connection portion and a weakened portion provided along an edge of the first connection portion, and configured to rupture along the weakened portion when an internal pressure of the battery cell reaches a threshold value, thereby relieving the internal pressure; The device further includes a securing structure for fixedly connecting the first connecting portion to the first tab, thereby limiting movement of the first connecting portion.

[0006] In the above technical solution, the first connecting portion of the end cap is fixedly connected to the first tab of the electrode assembly by a fixing structure. In this way, the first tab of the electrode assembly can restrict the movement of the first connecting portion during use of the battery cell, thereby reducing deformation and flipping of the end cap, reducing the alternating stress endured by the fragile portion, delaying fatigue and aging of the fragile portion of the end cap, and reducing the risk of premature rupture and relief of the end cap when the battery cell is normally used, thereby contributing to improving the safety and stability of the battery cell.

[0007] In some embodiments, the first connection portion is electrically connected to the first tab via a fastening structure.

[0008] In the above technical solution, the end cap can be charged and can serve as the output pole of the battery cell, thereby eliminating one of the conventional electrode terminals and simplifying the structure of the battery cell.

[0009] In some embodiments, the securing structure is configured to break at least a portion thereof to interrupt the connection between the first connection portion and the first tab when the internal pressure of the battery cell reaches a threshold value.

[0010] In the above technical solution, after the connection between the first connecting part and the first tab is cut off, the first tab no longer restricts the movement of the first connecting part, and as the weak part ruptures, the first connecting part is impacted by air pressure and cracks, thereby enlarging the passage for relieving the internal pressure, allowing the internal pressure to be relieved quickly and improving safety.

[0011] In some embodiments, the securing structure is a weld formed by welding the first tab and the first connecting portion.

[0012] In the above technical solution, the first connection part and the first tab are directly connected by welding, which can simplify the structure of the battery cell.

[0013] In some embodiments, the battery cell further includes a current collecting member disposed between the end cap and the first tab, for connecting the first connection portion to the first tab to establish 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 being a welded portion formed by welding a portion of the current collecting member to the first tab, and the second fixing structure being a welded portion formed by welding another portion of the current collecting member to the first connection portion.

[0014] In the above technical solution, a current collecting member is provided on the battery cell, and the current collecting member is welded to the first connection portion and the first tab, respectively, to achieve electrical connection between the end cap and the first tab. The current collecting member is closely attached to the first connection portion, reducing the risk of micro-cracks occurring in the first connection portion, improving sealing performance, and reducing safety risks.

[0015] In some embodiments, the current collecting member includes a first current collecting portion and a second current collecting portion, the first current collecting portion surrounds the outside of the second current collecting portion, the first fixing structure is a weld formed by welding the first current collecting portion to the first tab, and the second fixing structure is a weld formed by welding the second current collecting portion to the first connection portion.

[0016] In the above technical solution, the first fixing structure and the second fixing structure are formed on the first current collecting part and the second current collecting part, respectively, so that the first fixing structure does not affect the welding between the first connecting part and the current collecting member, and the connection strength between the first connecting part and the current collecting member can be increased.

[0017] In some embodiments, the second fixing structure is configured to break and interrupt the connection between the second current collecting portion and the first connecting portion when the internal pressure of the battery cell reaches a threshold value.

[0018] In the above technical solution, after the connection between the first connecting part and the second current collecting part is cut off, the first tab no longer restricts the movement of the first connecting part by the current collecting member, and as the weak part ruptures, the first connecting part is impacted by air pressure and cracks, thereby enlarging the passage for relieving the internal pressure, allowing the internal pressure to be relieved quickly and improving safety.

[0019] In some embodiments, the connection strength between the second current collector and the first connection portion is less than the connection strength between the first current collector and the first tab.

[0020] In the above technical solution, when a thermal runaway occurs in the battery cell, the end cap applies a tensile force to the current collecting member and the first tab due to the action of air pressure. Because the connection strength between the second current collecting member and the first connecting member is weaker than the connection strength between the first current collecting member and the first tab, the current collecting member first separates from the first connecting member. After the current collecting member separates from the first connecting member, the current collecting member is no longer subjected to the tensile force of the end cap. This maintains a fixed connection between the current collecting member and the first tab and reduces the risk of the current collecting member blocking the passage for relieving internal pressure.

[0021] In some embodiments, the first connection 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 toward the electrode assembly, and a first recess recessed from the outer surface of the first plate toward the electrode assembly at a position on the first connection portion corresponding to the first protrusion. The weakened portion is located on the outside of the first plate and is provided along the outer edge of the first plate. The second current collecting portion and the first protrusion are pressed and welded to each other to form a second fixed structure.

[0022] In the above technical solution, the first recess can reduce the strength of the first protrusion and increase its elasticity. Thus, when the battery cell vibrates, the first protrusion can release stress through deformation, reducing the stress transmitted to the weak part and delaying fatigue and aging of the weak part. The first recess can further reduce the thickness of the first protrusion, reducing the energy required to weld the first protrusion and the second current collecting part, reducing the heat transmitted to the weak part and delaying fatigue and aging of the weak part.

[0023] In some embodiments, the first current collecting portion covers the weakened portion in the thickness direction of the end cap.

[0024] In the above technical solution, the current collecting member can separate the weak part from the first tab, which reduces the active particles in the electrode assembly falling into the weak part and reduces the risk of the weak part being corroded.

[0025] In some embodiments, the first protrusion supports the current collecting member so as to form an escape gap for escaping the weakened portion between the first current collecting portion and the end cap.

[0026] In the above technical solution, the first connection part supports the first tab with the current collecting member, reducing the amount of rattle of the electrode assembly when the battery cell vibrates and improving the stability of the electrode assembly. The relief gap separates the weak part from the first current collecting part, preventing the first current collecting part from blocking the passage for relieving internal pressure when the weak part ruptures, thereby improving safety.

[0027] In some embodiments, the electrode assembly has a wound structure and includes a first through-hole at the center of the wound electrode assembly, and a second through-hole is provided in the second current collector, the second through-hole being configured to face the first through-hole so as to guide gas in the electrode assembly to the first connection part.

[0028] In the above technical solution, if thermal runaway occurs in the electrode assembly, high-temperature, high-pressure gas acts on the first connection part through the first through hole and the second through hole, and the connection between the first connection part and the current collecting member can be quickly cut off.

[0029] In some embodiments, the end cap further includes a second connecting portion that surrounds the outside of the first connecting portion and is fixedly connected to the housing, and the weakened 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.

[0030] In the above technical solution, the end cap is fixed to the housing by a second connecting part that surrounds the outside of the weak part, increasing the pitch between the weak part and the housing, reducing the stress transmitted to the weak part, and delaying fatigue and aging of the weak part.

[0031] In some embodiments, the weakened portion is adapted to rupture and break the connection between the first connection and the second connection when the internal pressure of the battery cell reaches a threshold value.

[0032] In the above technical solution, after the connection between the first connecting part and the second connecting part is cut off, the first connecting part and the second connecting part are inverted outward due to the action of the internal pressure, thereby enlarging the passage for relieving the internal pressure, allowing the internal pressure to be relieved quickly, and improving safety.

[0033] In some embodiments, the second connection portion includes a second plate and a second protrusion surrounding the outer side of the second plate, the second protrusion protruding from the inner side of the second plate in a direction facing the electrode assembly, and a second recess recessed from the outer side of the second plate in a direction facing the electrode assembly is formed at a position on the second connection portion corresponding to the second protrusion. The second plate surrounds the outer side of the fragile portion, and the second protrusion is used for fixed connection with the housing.

[0034] In the above technical solution, the second recess can reduce the strength of the second protrusion and increase the elasticity of the second protrusion. In this way, when the battery cell vibrates, the stress on the housing is transmitted to the second protrusion, and the second protrusion can release the stress through deformation, reducing the stress transmitted to the weak part and delaying fatigue and aging of the weak part.

[0035] In some embodiments, the outer surface of the second protrusion abuts the inner surface of the housing and is welded to the housing to seal the opening.

[0036] In the above technical solution, the welding provides a seal, reducing the risk of electrolyte leakage and improving the connection strength and current-passing capacity between the second protrusion and the housing. The second recess reduces the strength of the second protrusion and increases its elasticity. In this way, during the process of welding the second protrusion and the housing, the second protrusion deforms to release welding stress, reducing the risk of deformation or cracking of the welded area, reducing the welding stress transmitted to the weak part, and improving safety.

[0037] In some embodiments, the second protrusion and the first tab are pressed together to support the first tab.

[0038] In the above technical solution, the second protrusion supports the first tab, thereby reducing the amount of wobble of the electrode assembly when the battery cell vibrates, and improving the stability of the electrode assembly.

[0039] In some embodiments, the weakened portion surrounds the first connecting portion.

[0040] In the above technical solution, the weak part surrounds the first connecting part once, thereby increasing the range of the weak part, and increasing the exhaust rate when the weak part ruptures, thereby improving safety.

[0041] In some embodiments, the end cap is provided with a recessed groove and a weakened portion is formed in the end cap in an area facing the recessed groove.

[0042] In the above technical solution, the recessed groove reduces the thickness and strength of the weak part, so that when the internal pressure of the battery cell reaches a threshold, the end cap can burst along the weak part.

[0043] In some embodiments, the end cap includes a first nickel layer, a steel layer, and a second nickel layer, the first nickel layer being disposed on a surface of the steel layer facing the first tab, and the second nickel layer being disposed on a surface of the steel layer facing away from the first tab, the recessed groove being recessed from the surface of the first nickel layer facing away from the steel layer toward the second nickel layer, and the depth of the recessed groove being 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.

[0044] In the above technical solution, the recessed groove is located inside the end cap and does not destroy the outer second nickel layer during the forming process, so the second nickel layer protects the steel layer from the outside and reduces the risk of corrosion of the steel layer.Since the steel layer itself is not easily corroded by the electrolyte, even if the steel layer is exposed by the recessed groove, it does not pose a safety risk.

[0045] In some embodiments, an end cap is used to electrically connect the first tab to the housing.

[0046] In the above technical solution, the housing itself can be the output pole of the battery cell, and when multiple battery cells are assembled into a set, the housing can be electrically connected to the junction member, which not only increases the current passing area but also makes the structural design of the junction member more flexible.

[0047] In some embodiments, the housing further includes a sidewall and a bottom wall connected to the sidewall, the sidewall extending in the thickness direction of the end cap and surrounding 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 tab having a polarity opposite to that of the first tab, the second tab being provided at one end of the electrode assembly remote from the opening. The battery cell further includes an electrode terminal attached to the electrode lead-out hole, the electrode terminal being electrically connected to the second tab.

[0048] In the above technical solution, the bottom wall and the electrode terminals can be the two output poles of the battery cell, thus simplifying the structure of the battery cell and ensuring the current passing capacity of the battery cell. The bottom wall and the electrode terminals are located at the same end of the battery cell, so that when multiple battery cells are assembled into a set, the junction members can be assembled on the same side of the battery cells, thus simplifying the assembly process and improving assembly efficiency.

[0049] In some embodiments, the bottom wall and side wall are an integrally formed structure.

[0050] According to the above technical solution, the process of connecting the bottom wall and the side wall can be omitted.

[0051] In some embodiments, the first tab is a negative tab and the base material of the housing is steel.

[0052] In the above technical solution, the housing is electrically connected to the negative electrode tab, i.e., the housing is in a low potential state. The steel housing is less susceptible to corrosion by the electrolyte in a low potential state, reducing safety risks.

[0053] In some embodiments, the battery cells are cylindrical battery cells.

[0054] In a second aspect, an embodiment of the present application provides a battery including a battery cell according to any one of the embodiments of the first aspect.

[0055] In a third aspect, embodiments of the present application provide a power consuming device including the battery of the second aspect for providing electrical energy.

[0056] In a fourth aspect, an embodiment of the present application provides a method for manufacturing a battery cell, the method comprising: providing a housing having an opening; providing an electrode assembly having a first tab on one end facing the opening, and mounting the electrode assembly within the housing; providing an end cap including a first connecting portion and a weakened portion along an edge of the first connecting portion, and connecting the end cap to the housing such that the end cap covers the opening; and fixedly connecting the first connecting portion to the first tab to form a fixed structure so as to limit movement of the first connecting portion; The end cap is configured to burst along the weakened portion when the internal pressure of the battery cell reaches a threshold, thereby relieving the internal pressure.

[0057] In a fifth aspect, an embodiment of the present application provides a battery cell manufacturing system, the battery cell manufacturing system comprising: a first providing device for providing a housing having an opening; a second presenting device for providing an electrode assembly having a first tab on one end facing the opening and for mounting the electrode assembly within the housing; a third providing device for providing an end cap including a first connecting portion and a weakened portion along an edge of the first connecting portion, the third providing device being configured to connect the end cap to the housing such that the end cap covers the opening; an assembly device for fixedly connecting the first connecting portion to the first tab to form a fixed structure so as to limit movement of the first connecting portion; The end cap is configured to burst along the weakened portion when the internal pressure of the battery cell reaches a threshold, thereby relieving the internal pressure. [Brief explanation of the drawings]

[0058] In order to more clearly describe the technical solutions of the embodiments of the present application, the drawings that need to be used in the embodiments of the present application will be briefly described below. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without any creative efforts. [Figure 1] 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application. [Figure 2] 1 is an exploded schematic view of a battery provided in accordance with some embodiments of the present application. [Figure 3] FIG. 3 is an exploded schematic view of the battery module shown in FIG. 2. [Figure 4] 1 is an exploded schematic view of a battery cell provided in accordance with some embodiments of the present application. [Figure 5] 1 is a cross-sectional schematic diagram of a battery cell provided in accordance with some embodiments of the present application. [Figure 6] 6 is an enlarged schematic view of the battery cell shown in FIG. 5 at a portion surrounded by a circle A. FIG. [Figure 7] FIG. 5 is a schematic local cross-sectional view of the end cap shown in FIG. 4. [Figure 8] FIG. 2 is a cross-sectional schematic view of a battery cell provided in accordance with another embodiment of the present application. [Figure 9] 9 is an enlarged schematic view of box B of the battery cell shown in FIG. 8. FIG. [Figure 10] 1 is a flowchart of a method for manufacturing a battery cell provided by some embodiments of the present application. [Figure 11] FIG. 1 is a schematic block diagram of a battery cell manufacturing system provided in accordance with some embodiments of the present application.

[0059] In the accompanying drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION OF THE INVENTION

[0060] In order to clarify the objectives, technical solutions and advantages of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, and are not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without any creative efforts fall within the scope of protection of the present application.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Terms used in the specification of the present application are merely for the purpose of describing specific embodiments and are not intended to limit the present application. The terms "comprise," "have," and any variations thereof in the specification, claims, and drawings of the present application are intended to cover a non-exclusive inclusion. Terms such as "first," "second," and the like in the specification, claims, and drawings of the present application are intended to distinguish between different objects and are not intended to describe a particular order or a primary-subordinate relationship.

[0062] When referring to an "embodiment" in this application, it means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. Appearances of this phrase in various places in the specification do not necessarily all refer to the same embodiment, nor are they mutually exclusive, independent, or alternative embodiments of other embodiments.

[0063] In the description of this application, unless otherwise specified or limited, the terms "attach," "connect," "couple," and "attach" should be understood in a broad sense, and may refer to, for example, a fixed connection, a detachable connection, an integral connection, a direct connection, an indirect connection via an intermediate medium, or internal communication between two elements. Those skilled in the art will be able to understand the specific meanings of the above terms in the present application depending on the specific circumstances.

[0064] The term "and / or" in this application merely describes the relationship between related objects and indicates that three relationships may exist, for example, A and / or B can represent three cases: A alone, a combination of A and B, and B alone. Also, the character " / " in this application generally indicates that the related objects before and after it are in an "or" relationship.

[0065] In the embodiments of the present application, the same reference numerals represent the same elements, and for the sake of brevity, detailed descriptions of the same elements in different embodiments will be omitted. It should be understood that the dimensions of each element in the embodiments of the present application, such as thickness, length, and width, and the overall dimensions of the integrated device, such as thickness, length, and width, are merely exemplary and do not impose any limitations on the present application.

[0066] As used herein, "plurality" means two or more (including two).

[0067] In the present application, the battery cells may include, but are not limited to, 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. The battery cells may have a cylindrical, flat, rectangular, or other shape, but are not limited to, in the present application.

[0068] The battery referred to in the embodiments of this application refers to a single physical module containing 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. The battery generally includes a housing for packaging one or more battery cells. The housing can prevent liquids or other foreign objects from affecting the charging or discharging of the battery cells.

[0069] The battery cell includes an electrode assembly and an electrolyte, and the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell operates mainly by the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is coated on the surface of the positive electrode current collector. The positive electrode current collector includes a positive electrode coating area and a positive electrode tab connected to the positive electrode coating area, and the positive electrode active material layer is coated on the positive electrode coating area, while the positive electrode tab is not coated with the positive electrode active material layer. Taking a lithium-ion battery as an example, the positive electrode current collector may be made of aluminum, and the positive electrode active material layer includes a positive electrode active material, which may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganese oxide, or the like. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode current collector includes a negative electrode coating area and a negative electrode tab connected to the negative electrode coating area, the negative electrode coating area being coated with a negative electrode active material layer, and the negative electrode tab not being coated with a negative electrode active material layer. The material of the negative electrode current collector may be copper, and the negative electrode active material layer includes a negative electrode active material, which may be carbon or silicon, etc. The material of the separator may be PP (polypropylene), PE (polyethylene), etc.

[0070] The battery cell further includes a housing and end caps, the housing having an opening and adapted to accommodate the electrode assembly, the electrode assembly being able to be assembled into the housing through the opening, and the end caps adapted to cover the opening of the housing to achieve a seal.

[0071] In the development of battery technology, various design factors must be simultaneously considered, including performance parameters such as energy density, cycle life, discharge capacity, and charge / discharge ratio, and battery safety must also be considered.

[0072] The pressure relief mechanism in a battery cell has a significant impact on the safety of the battery cell. For example, if a short circuit or overcharging occurs, thermal runaway may occur inside the battery cell, causing a sudden increase in pressure. In this case, the pressure relief mechanism operates to release the internal pressure and prevent the battery cell from exploding or catching fire.

[0073] The pressure relief mechanism is an element or member that operates to relieve the internal pressure of the battery cell when the internal pressure reaches a predetermined threshold. The design of this threshold varies depending on the design requirements. This threshold may depend on one or more of the materials of the positive electrode sheet, negative electrode sheet, electrolyte, and separator in the battery cell.

[0074] The pressure relief mechanism may take the form of an explosion-proof valve, a gas valve, a relief valve, or a safety valve, and may specifically take the form of a pressure-sensitive element or structure, i.e., when the internal pressure of the battery cell reaches a predetermined threshold, the pressure relief mechanism performs an operation, or a weak part provided in the pressure relief mechanism ruptures, thereby forming an opening or passage through which the internal pressure can be relieved.

[0075] The term "activation" as used herein refers to the pressure relief mechanism operating or being enabled to a predetermined state to relieve the internal pressure of the battery cell. The activation of the pressure relief mechanism may include, but is not limited to, rupturing, crushing, tearing, or opening at least a portion of the pressure relief mechanism. When the pressure relief mechanism is activated, the high-temperature, high-pressure material inside the battery cell is discharged as a discharge from the activation site. In this way, the battery cell can be relieved with a controllable pressure, avoiding the occurrence of a potentially more serious accident.

[0076] The discharged materials from battery cells referred to in this application include, but are not limited to, electrolyte, melted or torn positive and negative electrode sheets and separator fragments, high-temperature and high-pressure gases and flames generated by reactions, etc.

[0077] To simplify the battery cell structure, the inventors attempted to integrate a pressure relief mechanism into the end cap. For example, the inventors provided the end cap with a weak portion that ruptures along the weak portion when the internal pressure of the battery cell reaches a threshold, thereby relieving the internal pressure. When a short circuit or overcharging occurs, thermal runaway may occur inside the battery cell, causing a sudden increase in pressure. In this case, the rupture of the weak portion releases the internal pressure, preventing the battery cell from exploding or catching fire, thereby improving safety.

[0078] However, after discovering the problem of battery cells exploding and relieving when the internal pressure does not reach a predetermined threshold, the inventors analyzed and researched the structure and operating environment of battery cells. They found that the weak parts of the end caps can fatigue and age prematurely, lowering the opening threshold of the end caps and causing premature rupture when the internal pressure of the battery cell does not reach the original predetermined threshold. After further research, they found that the internal pressure of the battery cell can alternately increase and decrease during transportation, temperature changes, or charging and discharging, causing the end caps to flip back and forth. When the end caps flip back and forth over a long period of time, the weak parts can fatigue and age, lowering the opening threshold of the end caps.

[0079] In view of this, the embodiments of the present application provide a technical solution that limits the flipping of the end cap by fixing the end cap to the tab of the electrode assembly, reduces the alternating stress endured by the weak part, delays fatigue and aging of the weak part of the end cap, reduces the risk of premature rupture and relief of the end cap, and contributes to improving the safety and stability of the battery cell.

[0080] The technical solutions described in the embodiments of the present application are applied to batteries and battery-powered power-consuming devices.

[0081] The power consuming devices may be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, power tools, etc. The vehicles may be gasoline-powered automobiles, gas-powered automobiles, or new energy automobiles. The new energy automobiles may be rechargeable battery electric vehicles, hybrid electric vehicles, extended-range electric vehicles, etc. The spacecraft may include airplanes, rockets, space shuttles, spaceships, etc. The electric toys include game consoles, electric car toys, electric propulsion toy boats, electric car toys, and other stationary or mobile electric toys. The power tools include electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, electric impact drills, metal cutting power tools such as concrete vibrators and electric planers, polishing power tools, mounting power tools, and railroad power tools. The embodiments of the present application do not particularly limit the power consuming devices.

[0082] In the following embodiments, for ease of explanation, the power consuming device is a vehicle.

[0083] 1 is a structural schematic diagram of a vehicle provided according to some embodiments of the present application. As shown in FIG. 1, a battery 2 is provided inside the vehicle 1, and the battery 2 may be provided at the bottom, front, or rear of the vehicle 1. The battery 2 can be used to power the vehicle 1, for example, the battery 2 can be the operating power source for the vehicle 1.

[0084] The vehicle 1 may further include a controller 3 and a motor 4, where the controller 3 is used to control the battery 2 to power the motor 4, for example, to meet the operating power needs of the vehicle 1 for starting, navigation, and driving.

[0085] In some embodiments of the present application, the battery 2 can be used not only as an operating power source for the vehicle 1, but also as a driving power source for the vehicle 1, providing driving power to the vehicle 1 in place of, or in place of, gasoline or natural gas.

[0086] 2 is an exploded schematic diagram of a battery provided according to some embodiments of the present application. As shown in FIG. 2, the battery 2 includes a housing 5 and a battery cell (not shown in FIG. 2) housed within the housing 5.

[0087] The housing 5 is used to house the battery cells and may have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which are covered by each other and which jointly define a housing space 5c for housing the battery cells. The second housing portion 5b may have a hollow structure with an opening at one end, and the first housing portion 5a may have a plate-like structure, and the first housing portion 5a covers the open side of the second housing portion 5b to form the housing 5 having the housing space 5c. Both the first housing portion 5a and the second housing portion 5b may also have a hollow structure with an opening at one end, and the open side of the first housing portion 5a covers the open side of the second housing portion 5b to form the housing 5 having the housing space 5c. Of course, the first housing part 5a and the second housing part 5b may have various shapes such as a cylindrical body or a rectangular parallelepiped.

[0088] In order to improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing member such as a sealant or a seal ring may be provided between the first housing part 5a and the second housing part 5b.

[0089] Assuming that the first housing part 5a is covered on top of the second housing part 5b, the first housing part 5a may be referred to as the upper housing cover, and the second housing part 5b may be referred to as the lower housing.

[0090] The battery 2 may have one or more battery cells. If there are multiple battery cells, the multiple battery cells may be connected in series, parallel, or series-parallel, and a series-parallel connection includes both series and parallel connections of the multiple battery cells. The multiple battery cells may be directly connected in series, parallel, or series-parallel, and then the entire configuration of the multiple battery cells may be housed in the housing 5. Of course, the multiple battery cells may first be connected in series, parallel, or series-parallel to form a battery module 6, and the multiple battery modules 6 may then be further connected in series, parallel, or series-parallel to form a single whole and housed in the housing 5.

[0091] FIG. 3 is an exploded schematic view of the battery module shown in FIG.

[0092] 3, there are a plurality of battery cells 7, and the plurality of battery cells 7 are first connected in series, parallel, or series-parallel to form a battery module 6. The plurality of battery modules 6 are further connected in series, parallel, or series-parallel to form a whole, and are housed in a housing.

[0093] Electrical connection can be achieved between the multiple battery cells 7 in the battery module 6 via junction components, thereby realizing parallel connection, series connection, or series-parallel connection of the multiple battery cells 7 in the battery module 6.

[0094] FIG. 4 is an exploded schematic view of a battery cell provided according to some embodiments of the present application, FIG. 5 is a cross-sectional schematic view of a battery cell provided according to some embodiments of the present application, and FIG. 6 is an enlarged schematic view of the battery cell shown in FIG. 5 at circled frame A.

[0095] 4 to 6 , a battery cell 7 according to an embodiment of the present application includes a housing 20 having an opening 21, an electrode assembly 10 accommodated in the housing 20 and provided with a first tab 11 on one end facing the opening 21, and an end cap 30 used to cover the opening 21, including a first connection portion 31 and a weakened portion 32 provided along an edge of the first connection portion 31, and configured to rupture along the weakened portion 32 when the internal pressure of the battery cell 7 reaches a threshold value, thereby relieving the internal pressure. The battery cell 7 further includes a fixing structure 60 for restricting movement of the first connection portion 31 by fixedly connecting the first connection portion 31 to the first tab 11.

[0096] The electrode assembly 10 includes a first sheet, a second sheet, and a separator, and the separator is used to separate the first sheet and the second sheet. The first sheet and the second sheet have opposite polarities; in other words, one of the first sheet and the second sheet is a positive electrode sheet, and the other of the first sheet and the second sheet is a negative electrode sheet.

[0097] Optionally, the first sheet, the second sheet, and the separator are all strip-shaped, and are wound together to form a wound structure, which may be cylindrical, flat, or have other shapes.

[0098] Viewed from the outside, the electrode assembly 10 includes a main body 12, a first tab 11, and a second tab 13, with the first tab 11 and the second tab 13 protruding from the main body 12. The first tab 11 is a portion of the first sheet that is not coated with the active material layer, and the second tab 13 is a portion of the second sheet that is not coated with the active material layer. Correspondingly, one of the first tab 11 and the second tab 13 is a positive polarity tab, and the other is a negative polarity tab.

[0099] The first tab 11 and the second tab 13 may extend from the same side of the main body 12, or may extend from opposite sides.

[0100] Illustratively, the first tab 11 and the second tab 13 are provided on both sides of the main body 12, in other words, the first tab 11 and the second tab 13 are provided on both ends of the electrode assembly 10. Optionally, the first tab 11 is located at one end of the electrode assembly 10 facing the end cap 30, and the second tab 13 is located at one end of the electrode assembly 10 away from the end cap 30.

[0101] Alternatively, the first tab 11 may be wound multiple times around the central axis X of the electrode assembly 10. In other words, the first tab 11 includes multiple windings of tab layers. After winding is complete, the first tab 11 has a generally cylindrical shape, with a gap between adjacent two tab layers. In some embodiments, the first tab 11 may be processed to reduce the gap between the tab layers and facilitate connection of the first tab 11 to other conductive structures. For example, in some embodiments, the first tab 11 may be subjected to a leveling process so that the end region of the first tab 11 away from the main body 12 is converged and gathered. The leveling process forms a dense end surface at the end of the first tab 11 away from the main body 12, reducing the gap between the tab layers and facilitating connection of the first tab 11 to other conductive structures. Alternatively, in some embodiments, a conductive material may be filled between adjacent two tab layers to reduce the gap between the tab layers.

[0102] Optionally, the second tab 13 may be wound multiple times around the central axis X of the electrode assembly 10, and the second tab 13 may include multiple tab layers. Illustratively, the second tab 13 may also be subjected to a leveling process to reduce gaps between the tab layers of the second tab 13.

[0103] The housing 20 may be a hollow structure that is open on one side or on both sides. The end cap 30 covers the opening of the housing 20 and forms a sealed connection, thereby forming a chamber for containing the electrode assembly and the electrolyte.

[0104] The housing 20 may have various shapes, such as a cylindrical body or a rectangular parallelepiped. The shape of the housing 20 can be determined depending on 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.

[0105] Exemplarily, the housing 20 includes a side wall 22 and a bottom wall 23. The side wall 22 surrounds the outside of the electrode assembly 10, and the bottom wall 23 is connected to an end of the side wall 22. The side wall 22 has a cylindrical structure, and may be, for example, a circular or rectangular cylinder, and the bottom wall 23 has a plate-like structure, the shape of which corresponds to the shape of the side wall 22. Optionally, an opening 21 is formed at one end of the side wall 22, and the bottom wall 23 is connected to the other end of the side wall 22 that is remote from the opening 21.

[0106] The side wall 22 and the bottom wall 23 may be integrally formed, i.e., the housing 20 is a single, molded member. Of course, the side wall 22 and the bottom wall 23 may be two separate members connected by means of welding, riveting, adhesive, or the like.

[0107] The end cap 30 may be electrically connected to the electrode assembly 10, or may be provided so as to be insulated from the electrode assembly 10. Optionally, the end cap 30 is electrically connected to the first tab 11. Of course, the end cap 30 may be electrically connected to the first tab 11 directly, or may be electrically connected to the first tab 11 via another conductive member.

[0108] The end cap 30 is fixedly connected to the housing 20. For example, the end cap 30 may be connected to the housing 20 by welding, engagement, adhesion, or other means, thereby securing the end cap 30 to the housing 20. The end cap 30 may be electrically connected to the housing 20 or may be insulatively connected to the housing 20.

[0109] 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 tabs of the electrode assembly 10 or may be electrically connected to the tabs via another conductive member (e.g., end cap 30).

[0110] The end cap 30 and the housing 20 may be connected by welding, and thus the end cap 30 and the housing 20 may have the same polarity. For example, if the housing 20 needs to be positively charged, the end cap 30 may be used to electrically connect the housing 20 to a tab of positive polarity, and if the housing 20 needs to be negatively charged, the end cap 30 may be used to electrically connect the housing 20 to a tab of negative polarity. Of course, the housing 20 may be connected to the tab via other conductive structures, and this embodiment is not limited thereto.

[0111] The housing 20 and end cap 30 may be made of the same material or different materials.

[0112] The strength of the fragile portion 32 is weaker than the strength of the rest of the end cap 30, and the fragile portion 32 is therefore a portion where the end cap 30 is likely to rupture, break, tear, or open. In this embodiment, the fragile portion 32 may be formed by thinning a predetermined region of the end cap 30, by material treatment of a predetermined region of the end cap 30, by heat treatment of a predetermined region of the end cap 30, or by other means.

[0113] The fragile portion 32 extends in the circumferential direction of the first connecting portion 31 and is connected to an edge of the first connecting portion 31. For example, the fragile portion 32 may surround the first connecting portion 31 completely, or may surround only half, two-thirds, or three-quarters of the first connecting portion 31, and this embodiment is not limited thereto.

[0114] The fixing structure 60 may directly and fixedly connect the first connecting portion 31 to the first tab 11, or may indirectly and fixedly connect the first connecting portion 31 to the first tab 11 via another member.

[0115] The fixing structure 60 may be a welded portion formed by welding, an adhesive layer formed after the adhesive has hardened, or any other structure, as long as it can achieve a fixed connection between the first tab 11 and the first connecting portion 31.

[0116] The fixing structure 60 may be a conductive structure for electrically connecting the first connection portion 31 to the first tab 11, or of course, alternatively, the fixing structure 60 may be an insulating structure for isolating the first connection portion 31 and the first tab 11 so as to insulate them.

[0117] The strength of the fixing structure 60 may be set as needed. When the internal pressure of the battery cell 7 reaches a threshold, the fixing structure 60 can be broken by the action of the internal pressure and cut off the connection between the first connection portion 31 and the first tab 11. Of course, the fixing structure 60 may have a large strength, and when the internal pressure of the battery cell 7 reaches the threshold, the fixing structure 60 can maintain the connection between the first connection portion 31 and the first tab 11.

[0118] During transportation, temperature changes, or charging and discharging of battery cells, the internal pressure of the battery cell may alternately increase and decrease, causing the end cap to deform by either bulging away from the electrode assembly or denting toward the electrode assembly. When bulging and denting deformation occurs alternately in the end cap, the weak parts withstand the alternating stresses, causing alternating fatigue, aging, or fracture, which reduces the strength of the weak parts. If the internal pressure of the battery cell does not reach a predetermined threshold, the weak parts may rupture to relieve the internal pressure of the battery cell, causing the end cap to rupture prematurely and relieve the pressure.

[0119] In the embodiment of the present application, the first connecting portion 31 of the end cap 30 is fixedly connected to the first tab 11 of the electrode assembly 10 by the fixing structure 60. In this way, the first tab 11 of the electrode assembly 10 can restrict the movement of the first connecting portion 31 during use of the battery cell 7, thereby reducing deformation and flipping of the end cap 30, reducing the alternating stress endured by the fragile portion 32, delaying fatigue and aging of the fragile portion 32 of the end cap 30, and reducing the risk of premature rupture and relief of the end cap 30 when the battery cell 7 is normally used, thereby contributing to improving the safety and stability of the battery cell 7.

[0120] In some embodiments, the end cap 30 is an integrally formed structure.

[0121] In some embodiments, the weakened portion 32 surrounds the first connecting portion 31 once.

[0122] The weakened portion 32 is an annular structure that surrounds 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 surrounded by the weakened portion 32. Optionally, the area surrounded by the weakened portion 32 may be circular, rectangular, racetrack-shaped, or elliptical.

[0123] In this embodiment, the fragile portion 32 surrounds the first connecting portion 31 once, thereby increasing the range of the fragile portion 32, increasing the exhaust rate when the fragile portion 32 ruptures, and improving safety.

[0124] In some embodiments, the first connection portion 31 is electrically connected to the first tab 11 via a fastening structure 60 .

[0125] The fixing structure 60 is electrically conductive and can realize an electrical connection between the end cap 30 and the first tab 11 .

[0126] In this embodiment, the end cap 30 can be charged and can serve as the output pole of the battery cell 7, thereby eliminating one of the conventional electrode terminals and simplifying the structure of the battery cell 7.

[0127] In some embodiments, an end cap 30 is used to electrically connect the first tab 11 to the housing 20 .

[0128] In this embodiment, the housing 20 itself can be the output pole of the battery cell 7. When multiple battery cells 7 are assembled into a set, the housing 20 can be electrically connected to the junction member, which not only increases the current passing area but also makes the structural design of the junction member more flexible.

[0129] In some embodiments, the housing 20 further includes a side wall 22 and a bottom wall 23 connected to the side wall 22. The side wall 22 extends in the thickness direction Z of the end cap 30 and surrounds the outer periphery of the electrode assembly 10. An electrode lead-out hole 231 is provided in the bottom wall 23. The electrode assembly 10 further includes a second tab 13 having a polarity opposite to that of the first tab 11, and the second tab 13 is provided at one end of the electrode assembly 10 remote from the opening 21. The battery cell 7 further includes an electrode terminal 40 attached to the electrode lead-out hole 231, and the electrode terminal 40 is electrically connected to the second tab 13.

[0130] The second tab 13 may be directly electrically connected to the electrode terminal 40, or may be indirectly electrically connected to the electrode terminal 40 via another conductive structure.

[0131] The electrode terminal 40 is insulated from the bottom wall 23, and the electrode terminal 40 and the bottom wall 23 may have different polarities, and the electrode terminal 40 and the bottom wall 23 can be two output poles of the battery cell 7, respectively.

[0132] When the first tab 11 is a negative electrode tab and the second tab 13 is a positive electrode tab, the bottom wall 23 is a negative output electrode of the battery cell 7, and the electrode terminal 40 is a positive output electrode of the battery cell 7. When the first tab 11 is a positive electrode tab and the second tab 13 is a negative electrode tab, the bottom wall 23 is a positive output electrode of the battery cell 7, and the electrode terminal 40 is a negative output electrode of the battery cell 7.

[0133] The electrode terminal 40 is fixed to the bottom wall 23. The electrode terminal 40 may be fixed entirely to the outside of the bottom wall 23, or may extend into the interior of the housing 20 through the electrode lead-out hole 231.

[0134] The first tab 11 is located at one end of the electrode assembly 10 facing the end cap 30 so that the end cap 30 is electrically connected to the first tab 11, and correspondingly, the second tab 13 is located at one end of the electrode assembly 10 facing the bottom wall 23 so that the electrode terminal 40 is electrically connected to the second tab 13. In the embodiment of the present application, by providing the first tab 11 and the second tab 13 at both ends of the electrode assembly 10, the risk of electrical conduction between the first tab 11 and the second tab 13 can be reduced and the current passing area of ​​the first tab 11 and the current passing area of ​​the second tab 13 can be increased.

[0135] In this embodiment, the bottom wall 23 and the electrode terminal 40 can be the two output poles of the battery cell 7, thus simplifying the structure of the battery cell 7 and ensuring the current passing 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, so that when multiple battery cells 7 are assembled into a set, the junction members can be assembled on the same side of the battery cells 7, thereby simplifying the assembly process and improving assembly efficiency.

[0136] In some embodiments, the bottom wall 23 and the side wall 22 are an integrally formed structure. In this embodiment, the process of connecting the bottom wall 23 and the side wall 22 can be omitted. The housing 20 can be formed by a drawing process.

[0137] The electrode extraction holes 231 in the present embodiment are formed after the housing 20 is stretch-formed.

[0138] The inventor attempted to form a flange structure by bending the open end of the housing inward, and then roll the open end of the housing so that the flange structure would press against the end cap and secure it in place. The inventor attached electrode terminals to the end cap, and the flange structure and electrode terminals served as the two output electrodes of the battery cell. However, the larger the flange structure, the greater the risk of curling and wrinkling after molding. If curling and wrinkling occur in the flange structure, the surface of the flange structure becomes uneven, which can lead to poor welding when welding the flange structure to the joining component. This limits the size of the flange structure, resulting in insufficient current-carrying capacity for the battery cell.

[0139] In this embodiment, electrode lead-out holes 231 for attaching electrode terminals 40 are formed in the bottom wall 23 through a hole-drilling process, and the positive and negative output electrodes are provided at the end of the battery cell 7 away from the opening 21. The bottom wall 23 is formed during the molding process of the housing 20, which ensures the flatness of the bottom wall 23 even after the electrode lead-out holes 231 are drilled, thereby ensuring the strength of the connection between the bottom wall 23 and the junction member. At the same time, the flatness of the bottom wall 23 is not limited by its own dimensions, so the bottom wall 23 can have a large dimension, which can enhance the current-passing capacity of the battery cell 7.

[0140] In some embodiments, the first tab 11 is a negative tab and the base material of the housing 20 is steel.

[0141] The housing 20 is electrically connected to the negative electrode tab, i.e., the housing 20 is in a low potential state. The steel housing 20 is less susceptible to corrosion by the electrolyte in a low potential state, reducing safety risks.

[0142] In some embodiments, the housing 20 is welded to the end cap 30. The welding connects the housing 20 and the end cap 30, which not only improves the current-carrying capacity between the housing 20 and the end cap 30, but also ensures a tight seal.

[0143] In some embodiments, the base material of the housing 20 is the same as the base material of the end caps 30. Alternatively, the base material of the housing 20 and the base material of the end caps 30 are both steel.

[0144] In this embodiment, the base material of the housing 20 and the end caps 30 are the same, which ensures the welding strength between the housing 20 and the end caps 30 and ensures the sealing of the battery cells 7 .

[0145] In some embodiments, the battery cell 7 is a cylindrical battery cell, and accordingly, the electrode assembly 10 has a cylindrical structure, and the housing 20 has a cylindrical hollow structure.

[0146] In some embodiments, the fixing structure 60 is configured to be at least partially broken to interrupt 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 value.

[0147] If thermal runaway occurs in the battery cell 7, high-temperature, high-pressure gas is generated in the electrode assembly 10, and the internal pressure of the battery cell 7 increases as the gas increases. The end cap 30 deforms under the action of air pressure and applies a tensile force to the fixing structure 60. When the internal pressure of the battery cell 7 reaches a threshold, the end cap 30 pulls the fixing structure 60 under the action of air pressure so that it ruptures, and the fixed connection between the first connection portion 31 and the first tab 11 is interrupted.

[0148] In this embodiment, there is no restriction on the order in which the fixing structure 60 ruptures and the fragile portion 32 ruptures, and it is sufficient that both the fixing structure 60 and the fragile portion 32 rupture when the internal pressure of the battery cell 7 reaches this threshold.

[0149] In this embodiment, after the connection between the first connecting portion 31 and the first tab 11 is cut off, the first tab 11 no longer restricts the movement of the first connecting portion 31. As the weak portion 32 ruptures, the first connecting portion 31 is impacted by the air pressure and cracks, thereby enlarging the passage for relieving the internal pressure, allowing the internal pressure to be relieved quickly and improving safety.

[0150] Illustratively, the frangible portion 32 surrounds the first connection portion 31 once, and after the frangible portion 32 ruptures, the connection between the first connection portion 31 and the rest of the end cap 30 is cut off, and thus the first connection portion 31 is impacted and broken by the action of air pressure and detached from the battery cell 7. Alternatively, the frangible portion 32 may surround the first connection portion 31 less than once, and as the frangible portion 32 ruptures, the first connection portion 31 remains connected to the rest of the end cap 30, but the first connection portion 31 is inverted outward by the action of air pressure, creating a larger passage for relieving internal pressure.

[0151] In some embodiments, the battery cell 7 further includes a current collecting member 50 that is provided between the end cap 30 and the first tab 11 and that connects the first connection portion 31 to the first tab 11, thereby achieving electrical connection between the end cap 30 and the first tab 11. The fixing structure 60 includes a first fixing structure 61 and a second fixing structure 62, where the first fixing structure 61 is a welded portion formed by welding a portion of the current collecting member 50 to the first 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 connection portion 31.

[0152] A part of the current collecting member 50 is connected to the first tab 11 by welding, thereby realizing an electrical connection between the current collecting member 50 and the first tab 11. Another part of the current collecting member 50 is connected to the first connection portion 31 by welding, thereby realizing an electrical connection between the current collecting member 50 and the end cap 30.

[0153] In addition to the portion welded to the first tab 11 and the other portion welded to the first connection portion 31, the current collecting member 50 may include other portions.

[0154] After extensive research, the inventors found that the end surface of the first tab 11 facing the end cap 30 is not flat, making it difficult to fit tightly to the first connecting portion 31, and that if the first connecting portion 31 and the first tab 11 are directly welded together, microcracks may occur in the first connecting portion 31, causing a risk that the seal provided by the end cap 30 will become ineffective, and posing a safety risk.

[0155] In this embodiment, the current collecting member 50 is an independently formed member, and unlike the first tab 11 which is wound and formed, the shape of the current collecting member 50 can be adaptively adjusted according to the shape of the end cap 30 to ensure that the current collecting member 50 can be tightly attached to the first connection portion 31 of the end cap 30.

[0156] In this embodiment, a current collecting member 50 is provided on the battery cell 7, and the current collecting member 50 is welded to the first connection portion 31 and the first tab 11, respectively, to achieve electrical connection between the end cap 30 and the first tab 11. The current collecting member 50 is closely attached to the first connection portion 31, thereby reducing the risk of microcracks occurring in the first connection portion 31, improving sealing performance and reducing safety risks. Even if microcracks occur in the current collecting member 50 when the current collecting member 50 and the first tab 11 are welded together, this does not affect the sealing performance of the battery cell 7.

[0157] In this embodiment, the first fixing structure 61 and the second fixing structure 62 can limit the movement of the first connecting portion 31 by fixedly connecting the first connecting portion 31, the current collecting member 50 and the first tab 11.

[0158] In some embodiments, the current collecting member 50 includes a first current collecting portion 51 and a second current collecting portion 52, the first current collecting portion 51 surrounds the outside of the second current collecting portion 52, the first fixing structure 61 is a welded portion formed by welding the first current collecting portion 51 and the first tab 11, and the second fixing structure 62 is a welded portion formed by welding the second current collecting portion 52 and the first connection portion 31.

[0159] The first current collecting portion 51 has a ring-shaped structure that surrounds the outside of the second current collecting portion 52. Selectively, 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.

[0160] 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 .

[0161] The first fixing structure 61 and the second fixing structure 62 are structures formed after the material has gone through processes such as melting, cooling, and solidification, and both have uneven surfaces.

[0162] When assembling the battery cell 7, the current collecting member 50 is first pressed against and welded to the first tab 11 to form the first fixing structure 61, and then the first connection portion 31 and the current collecting member 50 are welded to form the second fixing structure 62. If the second fixing structure 62 and the first fixing structure 61 overlap along the thickness direction Z of the end cap 30, when welding the first connection portion 31 and the current collecting member 50, the portion of the first connecting portion 31 used for welding to the current collecting member 50 must be pressed against the first fixing structure 61. Because the surface of the first fixing structure 61 is uneven, if the portion of the first connecting portion 31 used for welding to the current collecting member 50 is pressed 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, resulting in poor welding, which will affect the connection strength between the first connecting portion 31 and the current collecting member 50 and pose the risk of forming microcracks in the first connecting portion 31.

[0163] In this embodiment, the first fixing structure 61 and the second fixing structure 62 are formed on the first current collecting portion 51 and the second current collecting portion 52, respectively, thereby preventing the first fixing structure 61 from affecting the welding between the first connection portion 31 and the current collecting member 50, and increasing the connection strength between the first connection portion 31 and the current collecting member 50.

[0164] In some embodiments, the second fixing structure 62 is configured to break and interrupt the connection between the second current collecting portion 52 and the first connecting portion 31 when the internal pressure of the battery cell 7 reaches a threshold value.

[0165] If thermal runaway occurs in the battery cell 7, high-temperature, high-pressure gas is generated in the electrode assembly 10, and the internal pressure of the battery cell 7 increases as the gas increases. The end cap 30 deforms under the action of air pressure and applies a tensile force to the second fixing structure 62. When the internal pressure of the battery cell 7 reaches a threshold value, the end cap 30 pulls the second fixing structure 62 under the action of air pressure so that it ruptures, and the fixed connection between the first connection portion 31 and the second current collecting portion 52 is interrupted.

[0166] After the connection between the first connecting portion 31 and the second current collecting portion 52 is cut off, the first tab 11 no longer restricts the movement of the first connecting portion 31 by the current collecting member 50. As the weak portion 32 ruptures, the first connecting portion 31 is impacted by air pressure and cracks, thereby enlarging the passage for relieving the internal pressure, allowing the internal pressure to be relieved quickly and improving safety.

[0167] In some embodiments, when the internal pressure of the battery cell 7 reaches a threshold, the first fixing structure 61 fixes the current collecting member 50 by maintaining the connection between the first tab 11 and the first current collecting portion 51, thereby reducing the risk that the current collecting member 50 will block the passage for relieving the internal pressure.

[0168] 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 tab 11 .

[0169] The connection strength between the second current collecting portion 52 and the first connection portion 31 may be characterized by the tensile strength of the second fixing structure 62, and the connection strength between the first current collecting portion 51 and the first tab 11 may be characterized by the tensile strength of the first fixing structure 61. The tensile strength of the first fixing structure 61 and the tensile strength of the second fixing structure 62 can be tested using a tensile tester. For example, the electrode assembly 10 is fixed to a clamp and the current collecting member 50 is pulled using a tensile tester, pulling the first fixing structure 61 to the point of rupture, separating the first tab 11 of the electrode assembly 10 and the current collecting member 50. 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.

[0170] If thermal runaway occurs in the battery cell 7, the end cap 30 applies a tensile force to the current collecting member 50 and the first tab 11 due to the action of air pressure. Because the connection strength between the second current collecting portion 52 and the first connecting portion 31 is weaker than the connection strength between the first current collecting portion 51 and the first tab 11, the current collecting member 50 first separates from the first connecting portion 31. After the current collecting member 50 separates from the first connecting portion 31, the current collecting member 50 is no longer subjected to the tensile force of the end cap 30. In this way, the current collecting member 50 and the first tab 11 are fixedly connected, and the risk of the current collecting member 50 blocking the passage for relieving internal pressure can be reduced.

[0171] In some embodiments, the first connection portion 31 includes a first protrusion 311 and a first plate 312 surrounding the outside of the first protrusion 311, the first protrusion 311 protruding from the inner surface of the first plate 312 in a direction facing the electrode assembly 10, and a first recess 313 recessed from the outer surface of the first plate 312 in a direction facing the electrode assembly 10 is formed at a position on the first connection portion 31 corresponding to the first protrusion 311. The fragile portion 32 is located on the outside of the first plate 312 and is provided along the outer edge of the first plate 312. The second current collecting portion 52 and the first protrusion 311 are pressed against each other and welded to form a second fixed structure 62.

[0172] The first plate 312 may have an annular flat plate structure, and has an inner surface and an outer surface that are opposite each other in the thickness direction Z, and the inner surface of the first plate 312 faces the electrode assembly 10. The first protrusion 311 protrudes from the fragile portion 32 in the direction facing the electrode assembly 10.

[0173] The first recess 313 can reduce the strength of the first protrusion 311 and increase the elasticity of the first protrusion 311. Thus, when the battery cell 7 vibrates, the first protrusion 311 releases stress by deformation, reducing the stress transmitted to the fragile portion 32 and delaying fatigue and aging of the fragile portion 32. The first recess 313 can further reduce the thickness of the first protrusion 311, reducing the energy required to weld the first protrusion 311 and the second current collecting portion 52 and reducing the heat transmitted to the fragile portion 32, thereby delaying fatigue and aging of the fragile portion 32.

[0174] In some embodiments, the first current collecting portion 51 covers the weakened portion 32 in the thickness direction Z of the end cap 30 .

[0175] The projection of the fragile portion 32 in the thickness direction Z is located within the projection of the first current collecting portion 51 in the thickness direction Z.

[0176] In this embodiment, the current collecting member 50 can separate the fragile portion 32 from the first tab 11, reducing the amount of active granules in the electrode assembly 10 that fall into the fragile portion 32 and reducing the risk of the fragile portion 32 being corroded.

[0177] In some embodiments, the first protrusion 311 supports the current collecting member 50 so as to form an escape gap G between the first current collecting portion 51 and the end cap 30 for the weak portion 32 to escape.

[0178] The relief gap G is a space that is formed between the first current collecting portion 51 and the end cap 30 and is not filled with other solid members. The relief gap G and the fragile portion 32 face each other in the thickness direction Z, and serves to allow the fragile portion 32 to escape.

[0179] The first connection portion 31 supports the first tab 11 by the current collecting member 50, reducing the amount of rattle of the electrode assembly 10 when the battery cell 7 vibrates, and increasing the stability of the electrode assembly 10. The relief gap G separates the fragile portion 32 and the first current collecting portion 51, thereby preventing the first current collecting portion 51 from blocking the passage for relieving internal pressure when the fragile portion 32 ruptures, thereby increasing safety.

[0180] In some embodiments, the electrode assembly 10 has a winding structure, and the electrode assembly 10 has a first through-hole 14 at the winding center. A second through-hole 521 is provided in the second current collecting portion 52, and the second through-hole 521 is configured to be provided opposite the first through-hole 14 so as to guide gas within the electrode assembly 10 to the first connecting portion 31.

[0181] In the thickness direction Z, the first through-hole 14 and the second through-hole 521 at least partially overlap each other, thereby connecting the first through-hole 14 and the second through-hole 521 to each other.

[0182] If thermal runaway occurs in the electrode assembly 10, high-temperature, high-pressure gas acts on the first connection portion 31 through the first through hole 14 and the second through hole 521, quickly cutting off the connection between the first connection portion 31 and the collecting member 50.

[0183] In some embodiments, the end cap 30 further includes a second connecting portion 33 that surrounds the outside of the first connecting portion 31 and is fixedly connected to the housing 20. The weakened 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.

[0184] The second connecting portion 33 may be connected to the housing 20 by welding, engagement, adhesion, or other means, thereby securing the end cap 30 to the housing 20. The second connecting portion 33 may be electrically connected to the housing 20 or insulatively connected to the housing 20.

[0185] The strength of the second connecting portion 33 is greater than the strength of the fragile portion 32 , and for example, the thickness of the second connecting portion 33 is greater than the thickness of the fragile portion 32 .

[0186] In this embodiment, the end cap 30 is fixed to the housing 20 by a second connecting portion 33 that surrounds the outside of the fragile portion 32, increasing the pitch between the fragile portion 32 and the housing 20, reducing the stress transmitted to the fragile portion 32, and delaying fatigue and aging of the fragile portion 32.

[0187] In some embodiments, the weakened portion 32 is adapted to burst and break the connection between the first connection portion 31 and the second connection portion 33 when the internal pressure of the battery cell 7 reaches a threshold value.

[0188] In this embodiment, after the connection between the first connecting part 31 and the second connecting part 33 is cut off, the first connecting part 31 and the second connecting part 33 are inverted outward due to the action of the internal pressure, thereby enlarging the passage for relieving the internal pressure, allowing the internal pressure to be relieved quickly, and improving safety.

[0189] For example, the housing 20 may be electrically connected to the first tab 11 via the end cap 30, and the housing 20 may serve as an output electrode of the battery cell 7. When the internal pressure of the battery cell 7 reaches a threshold, the fragile portion 32 ruptures to cut off the connection between the first connection portion 31 and the second connection portion 33, thus cutting off the connection between the electrode assembly 10 and the external circuit, stopping charging and discharging, slowing down gas generation in the electrode assembly 10, and improving safety.

[0190] Illustratively, the fixing structure 60 is configured to be at least partially broken when the internal pressure of the battery cell 7 reaches a threshold, thereby cutting off the connection between the first connecting portion 31 and the first tab 11. At the same time, as the weak portion 32 ruptures, the first connecting portion 31 detaches from the second connecting portion 33 under the action of air pressure, thereby enlarging the passage for relieving the internal pressure, allowing the internal pressure to be relieved quickly, and improving safety.

[0191] In some embodiments, the second connection portion 33 includes a second plate 332 and a second protrusion 331 surrounding the outside of the second plate 332, the second protrusion 331 protruding from the inner surface of the second plate 332 in a direction facing the electrode assembly 10, and a second recess 333 recessed from the outer surface of the second plate 332 in a direction facing the electrode assembly 10 is formed at a position on the second connection portion 33 corresponding to the second protrusion 331. The second plate 332 surrounds the outside of the fragile portion 32, and the second protrusion 331 is used for fixed connection to the housing 20.

[0192] The second plate 332 may have an annular flat plate structure, and has an inner surface and an outer surface that are arranged opposite each other in the thickness direction Z, with the inner surface of the second plate 332 facing the electrode assembly 10.

[0193] The second protrusion 331 protrudes from the fragile portion 32 in a direction facing the electrode assembly 10 .

[0194] Optionally, the second plate 332 and the current collecting member 50 at least partially overlap in the thickness direction Z.

[0195] The second recess 333 can reduce the strength of the second protrusion 331 and increase the elasticity of the second protrusion 331. In this way, when the battery cell 7 vibrates, the stress on the housing 20 is transmitted to the second protrusion 331, and the second protrusion 331 releases the stress by deformation, reducing the stress transmitted to the fragile portion 32 and delaying fatigue and aging of the fragile portion 32.

[0196] Illustratively, the weakened portion 32 is located between the first plate 312 and the second plate 332 and is used to connect the first plate 312 and the second plate 332 .

[0197] In some embodiments, the outer surface 331 a of the second protrusion 331 abuts against the inner surface of the housing 20 and is welded to the housing 20 to seal the opening 21 .

[0198] The outer surface 331a of the second protrusion 331 is the surface of the second protrusion 331 that faces the side wall 22 of the housing 20. The outer surface 331a of the second protrusion 331 is a cylindrical surface, and optionally, the outer surface 331a of the second protrusion 331 is a cylindrical surface.

[0199] The portion of the second protrusion 331 that extends into the housing 20 may be an interference fit, a cut-out fit, or a clearance fit with the housing 20. Optionally, the portion of the second protrusion 331 that extends into the housing 20 may be an interference fit with the housing 20, which can increase the connection strength between the housing 20 and the end cap 30 and improve the sealing performance.

[0200] Optionally, the second protrusion 331 and the side wall 22 of the housing 20 are connected by laser welding. During welding, a laser is irradiated onto the boundary between the second protrusion 331 and the side wall 22, and the laser melts and connects at least a portion of the outer surface 331a of the second protrusion 331 to a portion of the inner surface of the housing 20. The outer surface 331a of the second protrusion 331 abuts against the inner surface of the housing 20, thereby reducing the risk of the laser irradiating the inside of the housing 20 and burning the electrode assembly 10.

[0201] Alternatively, the laser may be irradiated onto the outer surface of the sidewall 22 away from the second protrusion 331 .

[0202] In this embodiment, the sealing is achieved by welding, which can reduce the risk of electrolyte leakage and increase the connection strength and current passing capacity between the second protrusion 331 and the housing 20 .

[0203] The second recess 333 can reduce the strength of the second protrusion 331 and increase the elasticity of the second protrusion 331. In this way, during the process of welding the second protrusion 331 to the housing 20, the second protrusion 331 can release the welding stress through deformation, thereby reducing the risk of the welded area being deformed or cracked, reducing the welding stress transmitted to the fragile part 32, and increasing safety.

[0204] In some embodiments, the second protrusion 331 and the first tab 11 are pressed against each other to support the first tab 11 .

[0205] In this embodiment, the second protrusion 331 supports the first tab 11, reduces the amount of rattle of the electrode assembly 10 when the battery cell 7 vibrates, and improves the stability of the electrode assembly 10.

[0206] The collecting member 50 supports the central region of the first tab 11, and the second convex portion 331 supports the edge region of the first tab 11, thus increasing the uniformity of the force received by the first tab 11 and reducing the risk of the sheet of the electrode assembly 10 shifting or becoming misaligned in the thickness direction Z.

[0207] When the first connection portion 31 detaches from the battery cell 7 due to the action of air pressure, the second protrusion 331 supports the first tab 11 and the current collecting member 50, thereby reducing the risk that the current collecting member 50 will block the passage for relieving internal pressure, ensuring smooth exhaust, and improving safety.

[0208] FIG. 7 is a schematic local cross-sectional view of the end cap shown in FIG.

[0209] As shown in FIG. 7, in some embodiments, the end cap 30 is provided with a recessed groove 34, and the weakened portion 32 is formed in the area of ​​the end cap 30 facing the recessed groove 34.

[0210] The thickness of the weakened portion 32 is smaller than the thickness of the first connecting portion, thereby making the strength of the weakened portion 32 smaller than the strength of the first connecting portion.

[0211] For example, the recessed grooves 34 can be formed by removing material from the end cap 30 by machining, which contributes to reducing the processing cost and difficulty. The weakened portions 32 and the recessed grooves 34 are provided corresponding to each other in the thickness direction of the end cap 30.

[0212] The recessed groove 34 may be provided on the inner surface of the end cap 30, and the weakened portion 32 is a portion of the end cap 30 located between the bottom surface of the recessed groove 34 and the outer surface of the end cap 30. Alternatively, the recessed groove 34 may be provided on the outer surface of the end cap 30, and the weakened portion 32 is a portion of the end cap 30 located between the bottom surface of the recessed groove 34 and the inner surface of the end cap 30.

[0213] Illustratively, 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 surfaces of the first plate 312 and the second plate 332 are flush with each other, and the outer surfaces of the first plate 312 and the second plate 332 are flush with each other. The recessed groove 34 is located between the first plate 312 and the second plate 332.

[0214] In this embodiment, the recessed groove 34 reduces the thickness and strength of the weak portion 32, so that the end cap 30 can burst along the weak portion 32 when the internal pressure of the battery cell 7 reaches a threshold.

[0215] In some embodiments, the end cap 30 includes a first nickel layer 30a, a steel layer 30b, and a second nickel layer 30c, where the first nickel layer 30a is provided on a surface of the steel layer 30b facing the first tab, and the second nickel layer 30c is provided on a surface of the steel layer 30b facing away from the first tab. The recessed 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 recessed 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.

[0216] The surface of the first nickel layer 30 a facing away from the steel layer 30 b is the inner surface of the end cap 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 cap 30 .

[0217] The end cap 30 is made of a metal composite plate. The first nickel layer 30a and the second nickel layer 30c serve to protect the steel layer 30b, reducing the risk of corrosion of the steel layer 30b by substances such as water and oxygen, and improving sealing performance.

[0218] 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.

[0219] The first nickel layer 30a and the second nickel layer 30c mainly play a role in corrosion resistance and may have a small thickness, while the steel layer 30b is the base structure of the end cap 30 and may have a large thickness.

[0220] In this embodiment, the recessed groove 34 is located inside the end cap 30 and does not destroy the external second nickel layer 30c during the forming process, so the second nickel layer 30c protects the steel layer 30b from the outside and reduces the risk of corrosion of the steel layer 30b. Because the steel layer 30b itself is not easily corroded by the electrolyte, even if the steel layer 30b is exposed by the recessed groove 34, it is unlikely to pose a safety risk.

[0221] FIG. 8 is a cross-sectional schematic view of a battery cell provided according to another embodiment of the present application, and FIG. 9 is an enlarged schematic view of box B of the battery cell shown in FIG.

[0222] As shown in FIGS. 8 and 9, in some embodiments, the fixing structure 60 is a welded portion formed by welding the first tab 11 and the first connecting portion 31 together.

[0223] In this embodiment, the first connection portion 31 and the first tab 11 are directly connected by welding, which simplifies the structure of the battery cell 7 and, for example, eliminates the need for a current collecting member.

[0224] FIG. 10 is a flowchart of a method for manufacturing a battery cell provided in accordance with some embodiments of the present application.

[0225] As shown in FIG. 10, the method for manufacturing a battery cell according to the embodiment of the present application includes the following steps S100 to S400.

[0226] At S100, a housing having an opening is provided.

[0227] In S200, an electrode assembly is provided having a first tab on one end facing the opening, and the electrode assembly is mounted within the housing.

[0228] In S300, an end cap is provided that includes a first connecting portion and a weakened portion along an edge of the first connecting portion, and the end cap is connected to the housing such that the end cap covers the opening.

[0229] In S400, the first connecting portion is fixedly connected to the first tab to form a fixed structure so as to restrict movement of the first connecting portion.

[0230] The end cap is configured to burst along the weakened portion when the internal pressure of the battery cell reaches a threshold, thereby relieving the internal pressure.

[0231] It should be noted that the structures related to the battery cells manufactured by the above-described battery cell manufacturing method can be referenced to the battery cells provided in the above-described embodiments.

[0232] FIG. 11 is a schematic block diagram of a battery cell manufacturing system provided in accordance with some embodiments of the present application.

[0233] As shown in FIG. 11, a battery cell manufacturing system 90 according to an embodiment of the present application includes: a first providing device 91 for providing a housing having an opening; a second presenting device (92) for providing an electrode assembly having a first tab on one end facing the opening and for mounting the electrode assembly within the housing; a third providing device (93) for providing an end cap including a first connecting portion and a weakened portion along an edge of the first connecting portion, and for connecting the end cap to the housing such that the end cap covers the opening; an assembly device (94) for fixedly connecting the first connecting portion to the first tab to form a fixed structure so as to limit movement of the first connecting portion; The end cap is configured to burst along the weakened portion when the internal pressure of the battery cell reaches a threshold, thereby relieving the internal pressure.

[0234] The structures related to the battery cells manufactured by the manufacturing system can refer to the battery cells provided by the above-mentioned embodiments.

[0235] It should be noted that, unless there is a conflict, the embodiments and features of the embodiments of the present application can be combined with each other.

[0236] Finally, it should be noted that the above embodiments are only used to explain the technical solutions of the present application, and are not intended to limit the same. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art can still understand that the technical solutions described in the above embodiments can be modified or some of the technical features can be substituted with equivalents, and such modifications and substitutions will not cause the substance of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, the battery cell comprising: a housing having an opening; an electrode assembly housed within the housing and having a first tab on one end facing the opening; an end cap used to cover the opening, including a first connection portion and a weakened portion provided along an edge of the first connection portion, and configured to rupture along the weakened portion when an internal pressure of the battery cell reaches a threshold value, thereby relieving the internal pressure; a fixing structure for fixedly connecting the first connecting portion to the first tab to limit movement of the first connecting portion; a current collecting member provided between the end cap and the first tab, for connecting the first connection portion and the first tab to realize 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 being a welded portion formed by welding a part of the current collecting member to the first tab, and the second fixing structure being a welded portion formed by welding another part of the current collecting member to the first connection portion, the current collecting member includes a first current collecting portion and a second current collecting portion, the first current collecting portion surrounds the outside of the second current collecting portion, the first fixing structure is a welded portion formed by welding the first current collecting portion and the first tab, and the second fixing structure is a welded portion formed by welding the second current collecting portion and the first connection portion, The battery cell, wherein the fixing structure is configured to be at least partially broken to interrupt the connection between the first connection portion and the first tab when the internal pressure of the battery cell reaches the threshold.

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

3. A battery cell, comprising: a housing having an opening; an electrode assembly housed within the housing and having a first tab on one end facing the opening; an end cap used to cover the opening, including a first connection portion and a weakened portion provided along an edge of the first connection portion, and configured to rupture along the weakened portion when an internal pressure of the battery cell reaches a threshold value, thereby relieving the internal pressure; a fixing structure for fixedly connecting the first connecting portion to the first tab to limit movement of the first connecting portion; a current collecting member provided between the end cap and the first tab, for connecting the first connection portion and the first tab to realize 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 being a welded portion formed by welding a part of the current collecting member to the first tab, and the second fixing structure being a welded portion formed by welding another part of the current collecting member to the first connection portion, the current collecting member includes a first current collecting portion and a second current collecting portion, the first current collecting portion surrounds the outside of the second current collecting portion, the first fixing structure is a welded portion formed by welding the first current collecting portion and the first tab, and the second fixing structure is a welded portion formed by welding the second current collecting portion and the first connection portion, The battery cell, wherein the second fixing structure is configured to break when the internal pressure of the battery cell reaches the threshold value, thereby interrupting the connection between the second current collecting portion and the first connection portion.

4. 4. The battery cell according to claim 1, wherein 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 tab.

5. A battery cell, comprising: a housing having an opening; an electrode assembly housed within the housing and having a first tab on one end facing the opening; an end cap used to cover the opening, including a first connection portion and a weakened portion provided along an edge of the first connection portion, and configured to rupture along the weakened portion when an internal pressure of the battery cell reaches a threshold value, thereby relieving the internal pressure; a fixing structure for fixedly connecting the first connecting portion to the first tab to limit movement of the first connecting portion; a current collecting member provided between the end cap and the first tab, for connecting the first connection portion and the first tab to realize 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 being a welded portion formed by welding a part of the current collecting member to the first tab, and the second fixing structure being a welded portion formed by welding another part of the current collecting member to the first connection portion, the current collecting member includes a first current collecting portion and a second current collecting portion, the first current collecting portion surrounds the outside of the second current collecting portion, the first fixing structure is a welded portion formed by welding the first current collecting portion and the first tab, and the second fixing structure is a welded portion formed by welding the second current collecting portion and the first connection portion, the first connection portion includes a first protrusion and a first plate surrounding the outside of the first protrusion, the first protrusion protruding from an inner surface of the first plate in a direction facing the electrode assembly, and a first recess recessed from an outer surface of the first plate in a direction facing the electrode assembly is formed at a position of the first connection portion corresponding to the first protrusion, the fragile portion is located outside the first plate body and is provided along an outer edge of the first plate body, The second current collecting portion and the first protrusion are pressed against each other and welded to form the second fixing structure.

6. The battery cell according to claim 5 , wherein the first current collecting portion covers the weakened portion in a thickness direction of the end cap.

7. the first protrusion supports the current collecting member so as to form a clearance gap between the first current collecting portion and the end cap; 7. The battery cell according to claim 5, wherein the clearance gap is a space formed between the first current collecting portion and the end cap that is not filled with another solid member.

8. A battery cell, comprising: a housing having an opening; an electrode assembly housed within the housing and having a first tab on one end facing the opening; an end cap used to cover the opening, including a first connection portion and a weakened portion provided along an edge of the first connection portion, and configured to rupture along the weakened portion when an internal pressure of the battery cell reaches a threshold value, thereby relieving the internal pressure; a fixing structure for fixedly connecting the first connecting portion to the first tab to limit movement of the first connecting portion; a current collecting member provided between the end cap and the first tab, for connecting the first connection portion and the first tab to realize 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 being a welded portion formed by welding a part of the current collecting member to the first tab, and the second fixing structure being a welded portion formed by welding another part of the current collecting member to the first connection portion, the current collecting member includes a first current collecting portion and a second current collecting portion, the first current collecting portion surrounds the outside of the second current collecting portion, the first fixing structure is a welded portion formed by welding the first current collecting portion and the first tab, and the second fixing structure is a welded portion formed by welding the second current collecting portion and the first connection portion, The electrode assembly has a winding structure, and the electrode assembly has a first through hole at the winding center, A battery cell configured such that a second through hole is provided in the second current collecting portion, and the second through hole is provided opposite the first through hole so as to guide gas within the electrode assembly to the first connection portion.

9. the end cap further includes a second connecting portion that surrounds the outside of the first connecting portion and is fixedly connected to the housing; The battery cell according to any one of claims 1 to 8, wherein the fragile portion is located between the first connection portion and the second connection portion and is used to connect the first connection portion and the second connection portion.

10. 10. The battery cell according to claim 9, wherein the weakened portion is adapted to burst and cut off the connection between the first connection portion and the second connection portion when the internal pressure of the battery cell reaches the threshold value.

11. A battery cell, comprising: a housing having an opening; an electrode assembly housed within the housing and having a first tab on one end facing the opening; an end cap used to cover the opening, including a first connection portion and a weakened portion provided along an edge of the first connection portion, and configured to rupture along the weakened portion when an internal pressure of the battery cell reaches a threshold value, thereby relieving the internal pressure; a fixing structure for fixedly connecting the first connecting portion to the first tab to limit movement of the first connecting portion; a current collecting member provided between the end cap and the first tab, for connecting the first connection portion and the first tab to realize 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 being a welded portion formed by welding a part of the current collecting member to the first tab, and the second fixing structure being a welded portion formed by welding another part of the current collecting member to the first connection portion, the current collecting member includes a first current collecting portion and a second current collecting portion, the first current collecting portion surrounds the outside of the second current collecting portion, the first fixing structure is a welded portion formed by welding the first current collecting portion and the first tab, and the second fixing structure is a welded portion formed by welding the second current collecting portion and the first connection portion, the end cap further includes a second connecting portion that surrounds the outside of the first connecting portion and is fixedly connected to the housing; the weak portion is located between the first connection portion and the second connection portion and is used to connect the first connection portion and the second connection portion; the second connection portion includes a second plate and a second protrusion surrounding the outside of the second plate, the second protrusion protruding from the inner surface of the second plate in a direction facing the electrode assembly, and a second recess recessed from the outer surface of the second plate in a direction facing the electrode assembly is formed at a position of the second connection portion corresponding to the second protrusion; The second plate surrounds the outside of the weak portion, and the second protrusion is a battery cell used for fixedly connecting to the housing.

12. The battery cell according to claim 11 , wherein an outer surface of the second protrusion abuts against an inner surface of the housing and is welded to the housing to seal the opening.

13. The battery cell according to claim 11 or 12, wherein the second protrusion and the first tab are pressed against each other to support the first tab.

14. The battery cell according to any one of claims 1 to 13, wherein the fragile portion completely surrounds the first connection portion.

15. The battery cell according to any one of claims 1 to 14, wherein the end cap has a recessed groove, and the weakened portion is formed in a region of the end cap facing the recessed groove.

16. A battery cell, comprising: a housing having an opening; an electrode assembly housed within the housing and having a first tab on one end facing the opening; an end cap used to cover the opening, including a first connection portion and a weakened portion provided along an edge of the first connection portion, and configured to rupture along the weakened portion when an internal pressure of the battery cell reaches a threshold value, thereby relieving the internal pressure; a fixing structure for fixedly connecting the first connecting portion to the first tab to limit movement of the first connecting portion; a current collecting member provided between the end cap and the first tab, for connecting the first connection portion and the first tab to realize 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 being a welded portion formed by welding a part of the current collecting member to the first tab, and the second fixing structure being a welded portion formed by welding another part of the current collecting member to the first connection portion, the current collecting member includes a first current collecting portion and a second current collecting portion, the first current collecting portion surrounds the outside of the second current collecting portion, the first fixing structure is a welded portion formed by welding the first current collecting portion and the first tab, and the second fixing structure is a welded portion formed by welding the second current collecting portion and the first connection portion, a recessed groove is provided in the end cap, and the weakened portion is formed in a region of the end cap facing the recessed groove; the end cap includes a first nickel layer, a steel layer, and a second nickel layer, the first nickel layer being disposed on a surface of the steel layer facing the first tab, and the second nickel layer being disposed on a surface of the steel layer facing away from the first tab; a battery cell in which the recessed groove is recessed from a surface of the first nickel layer away from the steel layer toward the second nickel layer, and a depth of the recessed groove is greater than a thickness of the first nickel layer and less than a sum of the thicknesses of the first nickel layer and the steel layer.

17. The battery cell according to any one of claims 1 to 16, wherein the end cap is used to electrically connect the first tab to the housing.

18. the housing further includes a side wall and a bottom wall connected to the side wall, the side wall extending in a thickness direction of the end cap and surrounding an outer periphery of the electrode assembly, and an electrode lead-out hole formed in the bottom wall; the electrode assembly further includes a second tab having a polarity opposite to that of the first tab, the second tab being provided at an end of the electrode assembly away from the opening; The battery cell according to claim 17 , further comprising an electrode terminal attached to the electrode lead-out hole, the electrode terminal being electrically connected to the second tab.

19. 20. The battery cell of claim 18, wherein the bottom wall and the side wall are an integrally formed structure.

20. 20. The battery cell according to claim 17, wherein the first tab is a negative electrode tab, and the base material of the housing is steel.

21. The battery cell according to any one of claims 1 to 20, wherein the battery cell is a cylindrical battery cell.

22. A battery comprising a plurality of battery cells according to any one of claims 1 to 21.

23. 23. A power consuming device comprising the battery of claim 22 for providing electrical energy.

24. A method for manufacturing a battery cell, comprising: providing a housing having an opening; providing an electrode assembly having a first tab on one end facing the opening, and mounting the electrode assembly within the housing; providing an end cap including a first connection portion and a weakened portion along an edge of the first connection portion, and connecting the end cap to the housing such that the end cap covers the opening; and fixedly connecting the first connecting portion to the first tab to form a fixed structure so as to limit movement of the first connecting portion; the end cap is configured to rupture along the weakened portion to relieve the internal pressure of the battery cell when the internal pressure of the battery cell reaches a threshold; a current collecting member provided between the end cap and the first tab, for connecting the first connection portion and the first tab to realize 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 being a welded portion formed by welding a part of the current collecting member to the first tab, and the second fixing structure being a welded portion formed by welding another part of the current collecting member to the first connection portion, the current collecting member includes a first current collecting portion and a second current collecting portion, the first current collecting portion surrounds the outside of the second current collecting portion, the first fixing structure is a welded portion formed by welding the first current collecting portion and the first tab, and the second fixing structure is a welded portion formed by welding the second current collecting portion and the first connection portion, The method for manufacturing a battery cell, wherein the fixing structure is configured to be at least partially destroyed to cut off the connection between the first connection portion and the first tab when the internal pressure of the battery cell reaches the threshold.

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