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

Abstract

Embodiments of the present application provide a battery cell, a manufacturing method and system thereof, a battery, and an electrical device. The battery cell of the embodiment of the present application includes: a housing having an opening; an electrode assembly housed within the housing, the electrode assembly having a first tab at the end facing the opening; an end cap for covering the opening to seal the electrode assembly within the housing; and a current collecting member disposed between the end cap and the first tab. The current collecting member is configured to be welded to the end cap and the first tab, respectively, to achieve electrical connection between the end cap and the first tab. The present application can reduce the risk of microcracks in the end cap during welding, thereby improving sealing and safety.

Description

Technical Field

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

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

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

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

[0005] In one aspect, an embodiment of the present application provides a battery cell, comprising: a shell having an opening; an electrode assembly housed in the shell, the electrode assembly having a first electrode tab at an end facing the opening; an end cover for covering the opening to seal the electrode assembly in the shell; a current collecting member disposed between the end cover and the first electrode tab, the current collecting member being configured to be welded to the end cover and the first electrode tab, respectively, to achieve electrical connection between the end cover and the first electrode tab.

[0006] In the above solution, the electrical connection between the end cap and the first tab is achieved by welding the current collecting component to the end cap and the first tab separately. This allows the current collecting component to fit tightly against the end cap, reducing the risk of microcracks in the end cap, improving sealing performance, mitigating safety hazards, and enhancing safety. Even if microcracks develop in the current collecting component during welding, this will not affect the sealing of the battery cell.

[0007] In some embodiments, a portion of the current collecting member is used to abut and weld against the end cap to form a first weld portion, and another portion of the current collecting member is used to abut and weld against the first electrode tab to form a second weld portion. A projection of the first weld portion along the thickness direction of the end cap and a projection of the second weld portion along the thickness direction of the end cap do not overlap.

[0008] In the above solution, the projection of the first welding portion along the thickness direction of the end cover and the projection of the second welding portion along the thickness direction of the end cover do not overlap, so that the end cover and the current collecting component are not affected by the second welding portion when welding, thereby improving the welding reliability of the end cover and the current collecting component.

[0009] In some embodiments, the electrode assembly is wound along a central axis to form a first electrode tab. The first electrode tab includes N layers arranged around the central axis, with the central axis extending parallel to the thickness of the end cap. The first electrode tab consists of a first annular portion and a second annular portion surrounding the first annular portion. The number of layers in the first annular portion is N1, and the number of layers in the second annular portion is N2, where N = N1 + N2, |N1 - N2| is less than or equal to 2, and N1 and N2 are positive integers. The first annular portion is welded to the current collecting member to form a first portion, and the second annular portion is welded to the current collecting member to form a second portion connected to the first portion. The second welded portion consists of the first portion and the second portion.

[0010] In the above scheme, electrons in the area corresponding to the first annular portion in the electrode assembly can move along the first current path formed by the first annular portion, the first part, the current collecting component, the first welding portion and the end cover, and electrons in the area corresponding to the second annular portion in the electrode assembly can move along the second current path formed by the second annular portion, the second part, the current collecting component, the first welding portion and the end cover, and the boundary between the first annular portion and the second annular portion is roughly located in the radial middle area of ​​the first pole ear, that is, some layer structures in the middle area of ​​the first pole ear are welded to the current collecting component and form part of the second welding portion, which can reduce the difference between the first current path and the second current path to a certain extent, so as to improve the uniformity of current density, reduce internal resistance, and improve current flow capacity.

[0011] In some embodiments, N3 continuous layer structures in the first annular portion arranged near the second annular portion are welded to the current collecting component to form a first part, N4 continuous layer structures in the second annular portion arranged near the first annular portion are welded to the current collecting component to form a second part, and the N3 continuous layer structures are continuously arranged with the N4 continuous layer structures, N4>N3≥1, and N3 and N4 are positive integers.

[0012] In the above solution, because the second annular portion surrounds the outside of the first annular portion, the circumference of the layered structure in the second annular portion is greater than the circumference of the layered structure in the first annular portion. Therefore, the electrons in the region of the electrode assembly corresponding to the second annular portion have a longer path to travel between the layered structures of the second annular portion. In this solution, N4>N3. This increases the number of layers connected to the second portion, reduces the amount of electrons traveling between the layered structures of the second annular portion, and thus shortens the second current path. This further reduces the difference between the first and second current paths, thereby improving current density uniformity, reducing internal resistance, and improving current flow capacity.

[0013] In some embodiments, M consecutive layer structures among all the layer structures are welded to the current collecting member to form a second welding portion, wherein 1 / 3≤M / N≤1 / 2, M≥2, and M is a positive integer.

[0014] A larger M / N ratio reduces the internal resistance of the first tab, increases the area of ​​the second weld, and improves the current flow capacity between the first tab and the current collecting member. However, for a given current collecting member area, a larger M / N ratio reduces the area of ​​the first weld, and reduces the current flow capacity between the current collecting member and the end cap. The above solution limits the M / N ratio to 1 / 3-1 / 2 to balance the current flow capacity between the first tab and the current collecting member, and between the current collecting member and the end cap, optimizing the current flow capacity of the battery cell.

[0015] In some embodiments, the end cover includes a cover body and a first protrusion protruding from the inner surface of the cover body in a direction facing the first electrode ear, the first protrusion is used to abut and weld with the current collecting component to form a first welding portion, and to form a first avoidance gap between the current collecting component and the cover body for avoiding the second welding portion.

[0016] In the above solution, the provision of a first clearance gap for the second weld prevents the second weld from abutting the cover body, reducing the risk of the second weld from crushing the cover body. If the second weld abuts the cover body, over-alignment will occur between the end cap and the current collecting member, causing the second weld to interfere with the contact between the first protrusion and the current collecting member. By providing the first clearance gap, this solution prevents the second weld from interfering with the contact between the first protrusion and the current collecting member, ensuring the strength of the connection between the first protrusion and the current collecting member.

[0017] In some embodiments, a first recessed portion is formed on the end cover at a position corresponding to the first protrusion, which is recessed from the outer surface of the cover body in a direction facing the electrode assembly, and the bottom surface of the first recessed portion is closer to the first electrode tab than the inner surface of the cover body.

[0018] In the above solution, the thickness of the first protrusion is reduced by providing a first recess, which can reduce the welding power required for welding the first protrusion to the current collecting component, reduce heat generation, and reduce the risk of other components being burned. The first recess can reduce the strength of the first protrusion and improve the elastic deformation capacity of the first protrusion. In this way, in the process of the first protrusion pressing against the current collecting component, the first protrusion can release stress through deformation, reduce the impact force, and reduce the risk of the current collecting component and the first pole ear being crushed. This solution, while ensuring the protrusion degree of the first protrusion, further ensures the degree of depression of the first recess, so as to improve the elastic deformation capacity of the first protrusion and reduce the risk of the first protrusion crushing the current collecting component and the first pole ear during assembly.

[0019] In some embodiments, the first protrusion surrounds the outer side of the cover body, and the first welding portion is disposed on the outer side of the second welding portion.

[0020] In some embodiments, the outer side surface of the first protrusion abuts against the inner surface of the shell and is used to be welded to the shell to close the opening.

[0021] In the above solution, welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and flow capacity between the shell and the first protrusion.

[0022] In some embodiments, the end cap further includes an extension portion surrounding the outer side of the first protrusion, and a surface of the extension portion facing the first tab abuts against and is welded to an end surface of the housing surrounding the opening to close the opening.

[0023] In the above solution, when assembling the end cap and the shell, the end surface of the shell can play a limiting role in the thickness direction, reducing the risk of over-insertion of the end cap into the shell and improving assembly efficiency.

[0024] In some embodiments, the end cap further includes a second protrusion, the cap body surrounds the outer side of the second protrusion, and the second protrusion protrudes from the inner surface of the cap body in a direction facing the first electrode tab. A second recessed portion is formed on the end cap at a position corresponding to the second protrusion, which is recessed from the outer surface of the cap body in a direction facing the electrode assembly.

[0025] In the above solution, by providing the second convex portion and the second concave portion in the middle portion of the end cover, the strength of the end cover can be increased and the deformation of the end cover can be reduced.

[0026] In some embodiments, a weak portion is provided in a region of the second convex portion opposite to a bottom surface of the second concave portion, and the weak portion is configured to rupture when the internal pressure of the battery cell reaches a threshold value to release the internal pressure.

[0027] In this solution, a weakened portion is provided on the second protrusion to release internal pressure in the event of thermal runaway of the battery cell, thereby improving safety. The weakened portion is formed in the area of ​​the second protrusion opposite the bottom surface of the second recess. This increases the distance between the weakened portion and other external components, reducing the risk of the weakened portion being crushed by external components.

[0028] In some embodiments, a second avoidance gap is formed between the second protrusion and the current collecting member.

[0029] In the above solution, a second avoidance gap is formed between the second protrusion and the current collecting member to reduce the risk of the current collecting member blocking the exhaust channel when the weak portion ruptures, thereby ensuring smooth exhaust and reducing safety risks.

[0030] In some embodiments, the cover body surrounds the outer side of the first protrusion, and the first welding portion is disposed on the inner side of the second welding portion.

[0031] In some embodiments, a first recessed portion is formed on the end cap at a position corresponding to the first protrusion, recessed from the outer surface of the cap body in a direction facing the electrode assembly. The bottom surface of the first recessed portion is provided with a groove, the bottom of which is used to weld to the current collecting member to form a first welded portion.

[0032] In the above solution, the portion of the first protrusion located between the bottom surface of the groove and the top surface of the first protrusion forms a connecting portion, which is used to weld to the current collecting component to form the first welded portion. This solution reduces the thickness of the connecting portion of the first protrusion by providing the first recess and the groove. This reduces the welding power required to weld the connecting portion to the current collecting component, reduces heat generation, and reduces the risk of burns to other components.

[0033] In some embodiments, the end cap further includes a second protrusion surrounding the outer side of the cap body, the second protrusion protruding from the inner surface of the cap body in a direction facing the first tab, and the second protrusion is used to support the first tab.

[0034] In the above solution, the second protrusion can support the first electrode tab to reduce the shaking amplitude of the electrode assembly when the battery cell vibrates, thereby improving the stability of the electrode assembly.

[0035] In some embodiments, the outer side of the second protrusion abuts the inner surface of the housing and is welded to the housing to seal the opening. Welding can achieve a seal, reduce the risk of electrolyte leakage, and improve the connection strength and flow capacity between the second protrusion and the housing.

[0036] In some embodiments, a second recess is formed on the end cover at a position corresponding to the second protrusion, which is recessed from the outer surface of the cover body in a direction facing the electrode assembly, and the bottom surface of the second recess is closer to the first electrode tab than the inner surface of the cover body.

[0037] In the above solution, the second concave portion can reduce the strength of the second convex portion and increase its elasticity. Thus, during the welding process between the second convex portion and the housing, the second convex portion can release welding stress through deformation, thereby reducing the risk of deformation and cracking in the weld area and improving sealing performance. This solution, while ensuring the protrusion of the second convex portion, further ensures the degree of concavity of the second concave portion, thereby increasing the elasticity of the second convex portion and allowing the second convex portion to release welding stress through deformation.

[0038] In some embodiments, the cover body is provided with a weak portion, and the weak portion is configured to rupture when the internal pressure of the battery cell reaches a threshold value to release the internal pressure.

[0039] In this solution, a weakened portion is provided on the cover body to release internal pressure in the event of thermal runaway of the battery cell, improving safety. This embodiment also forms a first clearance gap between the current collecting member and the cover body to reduce the risk of the current collecting member blocking the venting channel if the weakened portion ruptures, ensuring smooth venting and minimizing safety risks.

[0040] In some embodiments, the current collecting member is a flat plate structure.

[0041] In the above solution, the flat-plate current collecting member is easier to form. It can be in full contact with the first electrode tab, thereby increasing the flow area and providing more uniform support for the first electrode tab, reducing the risk of thickness-wise displacement and misalignment of the electrode assembly's pole pieces. The flat-plate current collecting member also allows for close contact with the first protrusion, reducing the risk of microcracks during welding and improving sealing and safety.

[0042] In some embodiments, the first protrusion supports the first tab via the current collecting member.

[0043] In the above solution, the first protrusion supports the first electrode tab through the current collecting member, so as to reduce the shaking amplitude of the electrode assembly when the battery cell vibrates, thereby improving the stability of the electrode assembly.

[0044] In some embodiments, the current collecting component includes: a first current collecting portion, which is used to abut and weld with the end cover to form a first welding portion; a second current collecting portion, which is used to abut and weld with the first electrode tab to form a second welding portion, and the second current collecting portion is protruding from the surface of the first current collecting portion facing the electrode assembly, and the second current collecting portion is provided with an avoidance recess on the side away from the electrode assembly, and the avoidance recess is used to avoid the second welding portion.

[0045] In this solution, a relief recess is provided to clear the second weld portion, preventing the second weld portion from interfering with the contact between the first header and the end cap. This ensures the connection strength between the first header and the end cap and reduces the risk of the second weld portion crushing the end cap. The relief recess can reduce the thickness of the second header, thereby reducing the welding power required to weld the second header to the first tab, lowering heat generation and minimizing the risk of burns to other components.

[0046] In some embodiments, the end cover includes: a cover body, which is used to be welded with the first collecting portion to form a first welding portion; and a first protrusion, which surrounds the outside of the cover body and protrudes from the inner surface of the cover body in a direction facing the first pole ear, and the first protrusion is used to abut against the first pole ear to support the first pole ear.

[0047] In the above solution, the second current collecting portion supports the middle area of ​​the first pole ear, and the first protrusion supports the edge area of ​​the first pole ear. This can improve the uniformity of the force applied to the first pole ear and reduce the risk of displacement and misalignment of the pole piece of the electrode assembly in the thickness direction.

[0048] In some embodiments, a first recessed portion is formed on the end cover at a position corresponding to the first protrusion, which is recessed from the outer surface of the cover body in a direction facing the electrode assembly, and the bottom surface of the first recessed portion is closer to the first electrode tab than the inner surface of the cover body.

[0049] In the above solution, under the premise of ensuring the protrusion of the first convex portion, the concave degree of the first concave portion is further ensured to improve the elasticity of the first convex portion, reduce the impact force when the first convex portion is pressed against the first tab, and reduce the risk of the first tab being crushed.

[0050] In some embodiments, the outer side surface of the first protrusion abuts against the inner surface of the shell and is used to be welded to the shell to close the opening.

[0051] In the above solution, welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and flow capacity between the first protrusion and the shell.

[0052] In some embodiments, the end cap further includes a second protrusion, the cap body surrounds the outer side of the second protrusion, and the second protrusion protrudes from the inner surface of the cap body in a direction facing the first tab and extends into the avoidance recess. A second recess is formed on the end cap at a position corresponding to the second protrusion, which is recessed from the outer surface of the cap body in a direction facing the electrode assembly.

[0053] In the above solution, by providing the second convex portion and the second concave portion in the middle portion of the end cover, the strength of the end cover can be increased and the deformation of the end cover can be reduced.

[0054] In some embodiments, a weak portion is provided in the area of ​​the second protrusion opposite to the bottom surface of the second recess, the weak portion being configured to rupture when the internal pressure of the battery cell reaches a threshold value to release the internal pressure. The avoidance recess is further configured to separate the second current collecting portion from the weak portion.

[0055] In this solution, a weakened portion is provided on the second protrusion to release internal pressure in the event of thermal runaway of the battery cell, improving safety. The weakened portion is formed in the area of ​​the second protrusion opposite the bottom surface of the second recess. This increases the distance between the weakened portion and other external components, reducing the risk of the weakened portion being crushed by external components. The avoidance recess reduces the risk of the current collecting component blocking the exhaust channel if the weakened portion ruptures, ensuring smooth exhaust and reducing safety risks.

[0056] In some embodiments, the end cap is used to electrically connect the first tab and the housing.

[0057] In this solution, the housing itself can serve as the output terminal of the battery cell, eliminating a traditional electrode terminal and simplifying the battery cell structure. When multiple battery cells are assembled into a group, the housing can be electrically connected to the current collector, which not only increases the flow area but also makes the collector structure more flexible.

[0058] In some embodiments, the housing further includes sidewalls and a bottom wall connected to the sidewalls. The sidewalls extend along the thickness of the end cap and surround the periphery of the electrode assembly. The bottom wall is provided with an electrode lead-out hole. The electrode assembly further includes a second tab. The first and second tabs have opposite polarities and are located at opposite ends of the electrode assembly. The battery cell further includes an electrode terminal mounted in the electrode lead-out hole, the electrode terminal being electrically connected to the second tab.

[0059] In the above solution, the bottom wall and electrode terminals can serve as the two output poles of the battery cell, which can simplify the battery cell structure and ensure the battery cell's current carrying capacity. The bottom wall and electrode terminals are located at the same end of the battery cell. Therefore, when multiple battery cells are assembled into a group, the current collecting component can be assembled on the same side of the battery cells, which can simplify the assembly process and improve assembly efficiency.

[0060] In some embodiments, the bottom wall and the side walls are integrally formed, which can save the process of connecting the bottom wall and the side walls.

[0061] In some embodiments, the first electrode tab is a negative electrode tab, and the base material of the shell is steel.

[0062] In the above solution, the housing is electrically connected to the negative electrode tab and is in a low-potential state. The steel housing is not easily corroded by the electrolyte in a low-potential state, thereby reducing safety risks.

[0063] In some embodiments, the base material of the housing and the base material of the end cap are the same.

[0064] In the above solution, the base material of the shell and the base material of the end cover are the same, which can ensure the welding strength between the shell and the end cover and the sealing of the battery cell.

[0065] In some embodiments, the battery cells are cylindrical battery cells.

[0066] In a second aspect, an embodiment of the present application provides a battery comprising a plurality of battery cells according to any one of the embodiments of the first aspect.

[0067] In a third aspect, an embodiment of the present application provides an electrical device, comprising the battery of the second aspect, the battery being used to provide electrical energy.

[0068] In a fourth aspect, an embodiment of the present application provides a method for manufacturing a battery cell, comprising:

[0069] Providing an electrode assembly, the electrode assembly having a first electrode tab;

[0070] Providing a current collecting component, and welding the current collecting component to the first electrode tab;

[0071] providing a housing having an opening;

[0072] Installing the electrode assembly and the current collecting member into the housing, with the first electrode tab located at one end of the electrode assembly facing the opening;

[0073] Providing an end cover and closing the end cover on the opening so that the electrode assembly is sealed in the housing and the current collecting member is disposed between the end cover and the first electrode tab;

[0074] The end cap and the current collecting member are welded to achieve electrical connection between the end cap and the first electrode tab.

[0075] In a fifth aspect, an embodiment of the present application provides a battery cell manufacturing system, comprising:

[0076] A first providing device is used to provide an electrode assembly, wherein the electrode assembly has a first electrode tab;

[0077] A second providing device is used to provide a current collecting component and weld the current collecting component to the first electrode tab;

[0078] A third providing device is used to provide a housing having an opening;

[0079] a first assembling device for installing the electrode assembly and the current collecting member into the housing, with the first electrode tab positioned at an end of the electrode assembly facing the opening;

[0080] A fourth providing device is used to provide an end cover and cover the end cover on the opening so that the electrode assembly is sealed in the housing and the current collecting member is disposed between the end cover and the first electrode tab;

[0081] The second assembling device is used for welding the end cover and the current collecting member to achieve electrical connection between the end cover and the first electrode tab. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0083] Figure 1 A schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0084] Figure 2 An exploded schematic diagram of a battery provided in some embodiments of the present application;

[0085] Figure 3 for Figure 2 An exploded schematic diagram of the battery module shown;

[0086] Figure 4 An exploded schematic diagram of a battery cell provided in some embodiments of the present application;

[0087] Figure 5 A schematic cross-sectional view of a battery cell provided in some embodiments of the present application;

[0088] Figure 6 for Figure 5 An enlarged schematic diagram of a battery cell shown at box A;

[0089] Figure 7 A schematic diagram of the assembly of a current collecting member and an electrode assembly of a battery cell provided in some embodiments of the present application;

[0090] Figure 8 for Figure 7 A schematic structural diagram of the electrode assembly shown;

[0091] Figure 9 Schematic cross-sectional views of battery cells provided in other embodiments of the present application;

[0092] Figure 10 A schematic cross-sectional view of a battery cell provided in some other embodiments of the present application;

[0093] Figure 11 for Figure 10 An enlarged schematic diagram of a battery cell shown at circle B;

[0094] Figure 12 A schematic cross-sectional view of a battery cell provided in some further embodiments of the present application;

[0095] Figure 13 for Figure 12 An enlarged schematic diagram of a battery cell at box C is shown;

[0096] Figure 14 A schematic flow chart of a method for manufacturing a battery cell according to some embodiments of the present application;

[0097] Figure 15 A schematic block diagram of a battery cell manufacturing system provided in some embodiments of the present application.

[0098] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0099] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0100] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0101] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0102] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0103] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0104] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0105] The term "plurality" used in this application refers to two or more (including two).

[0106] In this application, battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, and the embodiments of this application are not limited thereto. Battery cells may be cylindrical, flat, rectangular, or in other shapes, and the embodiments of this application are not limited thereto.

[0107] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0108] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer, with the positive active material layer coated on the surface of the positive current collector. The positive current collector includes a positive current collecting region and a positive electrode tab protruding from the positive current collecting region. The positive current collecting region is coated with the positive active material layer, while at least a portion of the positive electrode tab is not coated with the positive active material layer. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material layer includes a positive active material. The positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, among others. The negative electrode sheet includes a negative current collector and a negative active material layer, with the negative active material layer coated on the surface of the current collector. The negative current collector includes a negative current collecting region and a negative electrode tab protruding from the negative current collecting region. The negative current collecting region is coated with the negative active material layer, while at least a portion of the negative electrode tab is uncoated with the negative active material layer. The negative current collector can be made of copper, and the negative active material layer includes a negative active material, such as carbon or silicon. The separator can be made of materials such as PP (polypropylene) or PE (polyethylene).

[0109] The battery cell further includes a housing and an end cap. The housing has an opening and is used to accommodate the electrode assembly. The electrode assembly can be assembled into the housing through the opening of the housing. The end cap is used to cover the opening of the housing to achieve sealing.

[0110] The inventors attempted to electrically connect the end cap to the electrode assembly's tab to facilitate current extraction. To achieve this electrical connection, the inventors welded the end cap to the tab. However, the inventors discovered that the end surface where the tab and end cap meet is uneven, making it difficult for the end cap to fit tightly. After welding the end cap to the tab, microcracks may form in the end cap, leading to the risk of seal failure and a safety hazard.

[0111] In light of this, embodiments of the present application provide a technical solution that achieves electrical connection between the end caps and the tabs by installing a current collecting component within the battery cell and welding the current collecting component to the end caps and tabs, respectively. This allows the current collecting component to fit tightly against the end caps, reducing the risk of microcracks in the end caps, improving sealing performance, and mitigating safety hazards. Even if microcracks develop in the current collecting component during welding, this will not affect the sealing of the battery cell.

[0112] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical devices using batteries.

[0113] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0114] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0115] Figure 1 This is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application. Figure 1 As shown, a battery 2 is provided inside the vehicle 1, and the battery 2 can be provided at the bottom, head, or tail of the vehicle 1. The battery 2 can be used to power the vehicle 1, for example, the battery 2 can be used as an operating power source for the vehicle 1.

[0116] The vehicle 1 may further include a controller 3 and a motor 4 . The controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of the vehicle 1 during startup, navigation, and driving.

[0117] In some embodiments of the present application, the battery 2 can not only serve as the operating power source of the vehicle 1, but also serve as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0118] Figure 2 Schematic diagram of the explosion of the battery provided in some embodiments of the present application. Figure 2 As shown, the battery 2 includes a box 5 and a battery cell ( Figure 2 The battery cells are housed in the box body 5 .

[0119] The housing 5 is used to house battery cells and can have various structures. In some embodiments, the housing 5 can include a first housing portion 5a and a second housing portion 5b. The first housing portion 5a and the second housing portion 5b overlap each other, and the first housing portion 5a and the second housing portion 5b together define a storage space 5c for accommodating the battery cells. The second housing portion 5b can be a hollow structure with one end open. The first housing portion 5a is a plate-like structure, and the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. The first housing portion 5a and the second housing portion 5b can also be hollow structures with one end open. The open side of the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0120] In order to improve the sealing performance after the first box body 5a and the second box body 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 5a and the second box body 5b.

[0121] Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box body.

[0122] In battery 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections. Multiple battery cells can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire battery module can be housed within housing 5. Alternatively, multiple battery cells can be first connected in series, in parallel, or in a hybrid configuration to form a battery module 6, and then multiple battery modules 6 can be connected in series, in parallel, or in a hybrid configuration to form a single unit housed within housing 5.

[0123] Figure 3 for Figure 2 An exploded diagram of the battery module is shown.

[0124] In some embodiments, as Figure 3 As shown, there are multiple battery cells 7, which are first connected in series, in parallel, or in mixed series to form a battery module 6. The multiple battery modules 6 are then connected in series, in parallel, or in mixed series to form a whole, which is accommodated in a box.

[0125] The multiple battery cells 7 in the battery module 6 can be electrically connected via a busbar component to achieve parallel connection, series connection, or mixed connection of the multiple battery cells 7 in the battery module 6 .

[0126] Figure 4 An exploded schematic diagram of a battery cell provided in some embodiments of the present application; Figure 5A schematic cross-sectional view of a battery cell provided in some embodiments of the present application; Figure 6 for Figure 5 An enlarged schematic diagram of a battery cell shown at box A; Figure 7 A schematic diagram of the assembly of a current collecting member and an electrode assembly of a battery cell provided in some embodiments of the present application; Figure 8 for Figure 7 Schematic diagram of the structure of the electrode assembly shown.

[0127] like Figures 4 to 8 As shown, the battery cell 7 of the embodiment of the present application includes: a shell 20 having an opening 21; an electrode assembly 10 accommodated in the shell 20, and the electrode assembly 10 has a first pole tab 12 at the end facing the opening 21; an end cover 30 for covering the opening 21 to seal the electrode assembly 10 in the shell 20; and a current collecting member 50, arranged between the end cover 30 and the first pole tab 12, and the current collecting member 50 is configured to be welded to the end cover 30 and the first pole tab 12 respectively to achieve electrical connection between the end cover 30 and the first pole tab 12.

[0128] The electrode assembly 10 includes a first electrode plate, a second electrode plate, and a separator, wherein the separator is used to separate the first electrode plate and the second electrode plate. The polarity of the first electrode plate and the second electrode plate are opposite. In other words, one of the first electrode plate and the second electrode plate is a positive electrode plate, and the other of the first electrode plate and the second electrode plate is a negative electrode plate.

[0129] Optionally, the first pole piece, the second pole piece and the separator are all strip-shaped structures, and the first pole piece, the second pole piece and the separator are wound together to form a wound structure. The wound structure can be a cylindrical structure, a flat structure or a structure of other shapes.

[0130] The electrode assembly 10 includes a main body 11, a first electrode tab 12, and a second electrode tab 13. The first electrode tab 12 and the second electrode tab 13 are connected to the main body 11. The first electrode tab 12 is the portion of the first electrode sheet not coated with the active material layer, and the second electrode tab 13 is the portion of the second electrode sheet not coated with the active material layer. Accordingly, one of the first electrode tab 12 and the second electrode tab 13 is a positive polarity tab, and the other is a negative polarity tab.

[0131] The first electrode tab 12 and the second electrode tab 13 are respectively provided on both sides of the main body 11. In other words, the first electrode tab 12 and the second electrode tab 13 are respectively provided at both ends of the electrode assembly 10. Optionally, the first electrode tab 12 is located at the end of the electrode assembly 10 facing the end cap 30, and the second electrode tab 13 is located at the end of the electrode assembly 10 facing away from the end cap 30.

[0132] The first electrode tab 12 is wound around the central axis X of the electrode assembly 10 and is generally cylindrical in shape. The first electrode tab 12 includes N layer structures 121 arranged around the central axis X, where N is a positive integer greater than 1.

[0133] The two ends of the first electrode tab 12 along the winding direction Y are an inner end 12 a and an outer end 12 b , respectively. In this embodiment, the layer structure 121 is divided based on the inner end 12 a of the first electrode tab 12 .

[0134] Specifically, the inner end 12a of the first electrode tab 12 is the leading end of the first layer structure 121, and the trailing end of the first layer structure 121 is aligned with the leading end of the first layer structure 121 in the radial direction of the first electrode tab 12. The first layer structure 121 circles around the central axis X. Correspondingly, the trailing end of the first layer structure 121 is the leading end of the second layer structure 121, and so on. The N layer structures 121 are connected end to end along the winding direction Y. When the layer structures 121 are divided, the leading end of each layer structure 121 is aligned with the inner end 12a of the first electrode tab 12 in the radial direction of the first electrode tab 12. The radial direction of the first electrode tab 12 is perpendicular to the central axis X and passes through the central axis X.

[0135] Exemplarily, the inner end 12 a and the outer end 12 b of the first electrode tab 12 are aligned in the radial direction of the first electrode tab 12 , so that each layer structure 121 circles the central axis X once.

[0136] Of course, alternatively, the inner end 12a and the outer end 12b of the first electrode tab 12 may not be aligned in the radial direction of the first electrode tab 12, so that the last layer structure 121 surrounds the central axis X for less than one circle. For example, the last layer structure 121 may surround the central axis X for 1 / 4 circle, 1 / 3 circle, 1 / 2 circle, 2 / 3 circle or 3 / 4 circle.

[0137] After winding is completed, the first pole tab 12 is generally cylindrical, with a gap between two adjacent layer structures 121. In embodiments of the present application, the first pole tab 12 may be processed to reduce the gap between the layer structures 121, thereby facilitating connection between the first pole tab 12 and the current collecting member 50. For example, in embodiments of the present application, the first pole tab 12 may be flattened to bring the end regions of the first pole tab 12 away from the main body 11 together; the flattening process forms a dense end surface at the end of the first pole tab 12 away from the main body 11, thereby reducing the gap between the layer structures 121 and facilitating connection between the first pole tab 12 and the current collecting member 50. Alternatively, in embodiments of the present application, conductive material may be filled between two adjacent ring layer structures 121 to reduce the gap between the layer structures 121.

[0138] Optionally, the second electrode tab 13 is wound multiple times around the central axis X of the electrode assembly 10 and includes multiple layers. Exemplarily, the second electrode tab 13 is also flattened to reduce gaps between the layers.

[0139] The shell 20 is a hollow structure with one side open. The end cover 30 covers the opening 21 of the shell 20 and forms a sealed connection to form a receiving cavity for accommodating the electrode assembly 10 and the electrolyte.

[0140] The housing 20 is a hollow structure, forming a space within it for accommodating the electrode assembly 10. The housing 20 can have various shapes, such as a cylinder or a rectangular parallelepiped. The shape of the housing 20 can be determined based 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 used; if the electrode assembly 10 has a rectangular parallelepiped structure, a rectangular parallelepiped housing can be used.

[0141] The housing 20 includes a sidewall 22 and a bottom wall 23. The sidewall 22 surrounds the outside of the electrode assembly 10, and the bottom wall 23 is connected to one end of the sidewall 22. The sidewall 22 has a cylindrical structure, for example, a circular cylinder or a square cylinder; the bottom wall 23 has a plate-like structure, and its shape corresponds to the shape of the sidewall 22. Optionally, one end of the sidewall 22 forms an opening 21, and the bottom wall 23 is connected to the end of the sidewall 22 facing away from the opening 21.

[0142] The sidewall 22 and the bottom wall 23 can be an integrally formed structure, that is, the housing 20 is an integrally formed component. Of course, the sidewall 22 and the bottom wall 23 can also be two components provided separately, and then connected together by welding, riveting, bonding, etc.

[0143] The shell 20 can be positively charged, negatively charged, or uncharged. When the shell 20 needs to be charged, the shell 20 can be directly connected to the tab of the electrode assembly 10 or electrically connected to the tab through other conductive components.

[0144] The end cap 30 and the housing 20 can be connected by welding, so that the end cap 30 and the housing 20 have the same polarity. For example, when the housing 20 needs to be positively charged, the end cap 30 can be used to electrically connect the housing 20 to the positive polarity tab; when the housing 20 needs to be negatively charged, the end cap 30 can be used to electrically connect the housing 20 to the negative polarity tab. Of course, the housing 20 can also be connected to the tab via other conductive structures, and this embodiment is not limited to this.

[0145] The housing 20 and the end cover 30 may be made of the same material or different materials.

[0146] The current collecting member 50 can connect the end cap 30 to the first electrode tab 12, thereby making the polarity of the end cap 30 the same as that of the first electrode tab 12. Optionally, the current collecting member 50 is a plate-shaped structure made of a metal material.

[0147] When assembling the battery cell 7, the current collecting member 50 is first welded to the first electrode tab 12. For example, the current collecting member 50 can be pressed against the first electrode tab 12, and then a laser is irradiated on the surface of the current collecting member 50 facing away from the first electrode tab 12. The laser melts and connects a portion of the current collecting member 50 and a portion of the first electrode tab 12.

[0148] After the electrode assembly 10 and the current collecting member 50 are installed in the housing 20, the end cap 30 is fitted to the opening 21 of the housing 20 and welded to the end cap 30 and the current collecting member 50. For example, a laser is irradiated on the surface of the end cap 30 facing away from the current collecting member 50, and the laser melts and connects a portion of the end cap 30 and a portion of the current collecting member 50.

[0149] At least a portion of the current collecting member 50 abuts against and fits tightly against the end cover 30, so as to facilitate welding of the current collecting member 50 and the end cover 30. Optionally, the surface of the current collecting member 50 abutting against the end cover 30 is a plane.

[0150] The current collecting member 50 is an independently formed member, which is different from the first electrode tab 12 formed by winding. The shape of the current collecting member 50 can be adaptively adjusted according to the shape of the end cover 30 to ensure that the current collecting member 50 can be closely attached to the end cover 30.

[0151] In this embodiment, the electrical connection between the end cap 30 and the first electrode tab 12 is achieved by welding the current collecting member 50 to the end cap 30 and the first electrode tab 12, respectively. The current collecting member 50 can be tightly fitted to the end cap 30, reducing the risk of microcracks in the end cap 30, improving sealing performance, reducing safety hazards, and enhancing safety. Even if microcracks develop in the current collecting member 50 during welding to the first electrode tab 12, this will not affect the sealing of the battery cell 7.

[0152] In some embodiments, the end cap 30 is used to electrically connect the first electrode tab 12 and the housing 20 .

[0153] In this embodiment, the housing 20 itself can serve as the output terminal of the battery cell 7, thereby eliminating a traditional electrode terminal and simplifying the structure of the battery cell 7. When multiple battery cells 7 are assembled into a group, the housing 20 can be electrically connected to the busbar, which not only increases the flow area but also makes the busbar structure more flexible.

[0154] In some embodiments, the housing 20 is welded to the end cap 30. Welding can not only achieve the connection between the housing 20 and the end cap 30, improve the flow capacity between the housing 20 and the end cap 30, but also ensure the sealing.

[0155] In some embodiments, the housing 20 further includes a sidewall 22 and a bottom wall 23 connected to the sidewall 22. The sidewall 22 extends along the thickness direction Z of the end cap 30 and surrounds the periphery of the electrode assembly 10. The bottom wall 23 defines an electrode lead-out hole 231. The electrode assembly 10 further includes a second electrode tab 13. The first electrode tab 12 and the second electrode tab 13 have opposite polarities and are located at opposite ends of the electrode assembly 10. The battery cell 7 further includes an electrode terminal 40 mounted in the electrode lead-out hole 231. The electrode terminal 40 is electrically connected to the second electrode tab 13.

[0156] The second electrode tab 13 may be directly electrically connected to the electrode terminal 40 , or may be indirectly electrically connected to the electrode terminal 40 through other conductive structures.

[0157] The electrode terminal 40 is insulated and disposed on the bottom wall 23 . The electrode terminal 40 and the bottom wall 23 may have different polarities. The electrode terminal 40 and the bottom wall 23 may serve as two output poles of the battery cell 7 , respectively.

[0158] When the first tab 12 is a negative tab and the second tab 13 is a positive tab, the bottom wall 23 is the negative output pole of the battery cell 7, and the electrode terminal 40 is the positive output pole of the battery cell 7. When the first tab 12 is a positive tab and the second tab 13 is a negative tab, the bottom wall 23 is the positive output pole of the battery cell 7, and the electrode terminal 40 is the negative output pole of the battery cell 7.

[0159] The electrode terminal 40 is fixed to the bottom wall 23. The electrode terminal 40 can be fixed as a whole to the outside of the bottom wall 23, or can extend into the interior of the housing 20 through the electrode lead-out hole 231.

[0160] The first electrode tab 12 is located at the end of the electrode assembly 10 facing the end cap 30, so as to facilitate electrical connection between the end cap 30 and the first electrode tab 12. Correspondingly, the second electrode tab 13 is located at the end of the electrode assembly 10 facing the bottom wall 23, so as to facilitate electrical connection between the electrode terminal 40 and the second electrode tab 13. In the embodiment of the present application, the first electrode tab 12 and the second electrode tab 13 are arranged at both ends of the electrode assembly 10, which can reduce the risk of electrical conduction between the first electrode tab 12 and the second electrode tab 13 and increase the flow area of ​​the first electrode tab 12 and the flow area of ​​the second electrode tab 13.

[0161] In this embodiment, the bottom wall 23 and the electrode terminal 40 can serve as the two output poles of the battery cell 7, which can simplify the structure of the battery cell 7 and ensure the current carrying capacity of the battery cell 7. The bottom wall 23 and the electrode terminal 40 are located at the same end of the battery cell 7. Therefore, when multiple battery cells 7 are assembled into a group, the current collecting component can be assembled to the same side of the battery cells 7, which can simplify the assembly process and improve assembly efficiency.

[0162] In some embodiments, the bottom wall 23 and the side wall 22 are integrally formed. This embodiment can omit the process of connecting the bottom wall 23 and the side wall 22. The housing 20 can be formed by a stretching process.

[0163] The electrode lead-out hole 231 in the embodiment of the present application is formed after the shell 20 is stretched.

[0164] The inventors have tried to roll the open end of the shell so that the open end of the shell is folded inward and forms a flange structure. The flange structure presses the end cover to fix the end cover. The inventors installed the electrode terminal on the end cover and used the flange structure and electrode terminal as the two output poles of the battery cell. However, the larger the size of the flange structure, the higher the risk of curling and wrinkling after forming; if the flange structure curls and wrinkles, it will cause the surface of the flange structure to be uneven, and when the flange structure is welded to the collector component, there will be problems with poor welding. Therefore, the size of the flange structure is relatively limited, resulting in insufficient current capacity of the battery cell.

[0165] In this embodiment, an electrode lead-out hole 231 for mounting the electrode terminal 40 is formed on the bottom wall 23 by a perforation process, thereby positioning the positive and negative output electrodes at the end of the battery cell 7 facing away from the outlet 21. The bottom wall 23 is formed during the molding process of the housing 20. The electrode lead-out hole 231 ensures the flatness of the bottom wall 23 and the connection strength between the bottom wall 23 and the current collector. Furthermore, the flatness of the bottom wall 23 is not constrained by its own dimensions, allowing it to be larger, thereby improving the current handling capacity of the battery cell 7.

[0166] In some embodiments, the first electrode tab 12 is a negative electrode tab, and the base material of the shell 20 is steel.

[0167] The housing 20 is electrically connected to the negative electrode tab, that is, the housing 20 is in a low potential state. The steel housing 20 is not easily corroded by the electrolyte in the low potential state, thereby reducing safety risks.

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

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

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

[0171] In some embodiments, a portion of the current collecting member 50 is used to abut and weld against the end cap 30 to form a first weld portion W1, and another portion of the current collecting member 50 is used to abut and weld against the first electrode tab 12 to form a second weld portion W2. The projection of the first weld portion W1 along the thickness direction Z of the end cap 30 and the projection of the second weld portion W2 along the thickness direction Z of the end cap 30 do not overlap.

[0172] In this embodiment, two different portions of the current collecting member 50 are welded to the end cover 30 and the first electrode tab 12 respectively, so that the projection of the first welding portion W1 along the thickness direction Z of the end cover 30 and the projection of the second welding portion W2 along the thickness direction Z of the end cover 30 do not overlap.

[0173] The first welding portion W1 and the second welding portion W2 are structures formed after the material undergoes processes such as melting, cooling and solidification, and the surfaces of the two are uneven.

[0174] During assembly of the battery cell 7, the current collecting member 50 is first pressed against and welded to the first electrode tab 12 to form the second weld W2. The end cap 30 and the current collecting member 50 are then welded to form the first weld W1. If the projection of the first weld W1 along the thickness direction Z of the end cap 30 overlaps with the projection of the second weld W2 along the thickness direction Z of the end cap 30, the portion of the end cap 30 welded to the current collecting member 50 will need to press against the second weld W2 during welding. Due to the uneven surface of the second weld W2, if the portion of the end cap 30 welded to the current collecting member 50 presses against the second weld W2, it will be difficult for the end cap 30 to form a close fit with the second weld W2. This can result in a poor weld, compromise the connection strength between the end cap 30 and the current collecting member 50, and increase the risk of microcracks forming in the end cap 30.

[0175] In this embodiment, the projection of the first welding portion W1 along the thickness direction Z of the end cover 30 and the projection of the second welding portion W2 along the thickness direction Z of the end cover 30 do not overlap. In this way, the end cover 30 and the current collecting component 50 are not affected by the second welding portion W2 when welding, thereby improving the welding reliability of the end cover 30 and the current collecting component 50.

[0176] In some embodiments, the electrode assembly 10 is wound along a central axis X to form a first electrode tab 12. The first electrode tab 12 includes N layers 121 arranged around the central axis X, with the central axis X extending parallel to the thickness direction Z of the end cap 30. The first electrode tab 12 consists of a first annular portion 122 and a second annular portion 123 surrounding the first annular portion 122. The number of layers 121 in the first annular portion 122 is N1, and the number of layers 121 in the second annular portion 123 is N2, where N = N1 + N2, |N1 - N2| is less than or equal to 2, and N1 and N2 are positive integers. The first annular portion 122 is welded to the current collecting member 50 to form a first portion W21. The second annular portion 123 is welded to the current collecting member 50 to form a second portion W22 connected to the first portion W21. The second welded portion W2 consists of the first portion W21 and the second portion W22.

[0177] Each layer structure 121 in the first annular portion 122 circles around the central axis X. The connection between the first annular portion 122 and the second annular portion 123 is radially aligned with the inner end 12 a of the first electrode tab 12 .

[0178] The electrons in the area of ​​the electrode assembly 10 corresponding to the first annular portion 122 can move along the first current path formed by the first annular portion 122, the first part W21, the current collecting member 50, the first welding portion W1 and the end cover 30, and the electrons in the area of ​​the electrode assembly 10 corresponding to the second annular portion 123 can move along the second current path formed by the second annular portion 123, the second part W22, the current collecting member 50, the first welding portion W1 and the end cover 30, and the boundary between the first annular portion 122 and the second annular portion 123 is roughly located in the radial middle area of ​​the first electrode ear.

[0179] In this embodiment, the boundary between the first annular portion 122 and the second annular portion 123 is roughly located in the radial middle area of ​​the first pole tab 12. Some layer structures 121 in the middle area of ​​the first pole tab 12 are welded to the current collecting component 50 and form a part of the second welding portion W2. This can reduce the difference between the first current path and the second current path to a certain extent, thereby improving the uniformity of the current density, reducing the internal resistance, and improving the current flow capacity.

[0180] In some embodiments, N3 continuous layer structures 121 in the first annular portion 122 that are arranged near the second annular portion 123 are welded to the current collecting member 50 to form a first part W21, and N4 continuous layer structures 121 in the second annular portion 123 that are arranged near the first annular portion 122 are welded to the current collecting member 50 to form a second part W22, and the N3 continuous layer structures 121 and the N4 continuous layer structures 121 are arranged continuously, N4>N3≥1, and N3 and N4 are positive integers.

[0181] Because the second annular portion 123 surrounds the outside of the first annular portion 122, the circumference of the layered structure 121 in the second annular portion 123 is greater than the circumference of the layered structure 121 in the first annular portion 122. Therefore, the electrons in the region of the electrode assembly 10 corresponding to the second annular portion 123 have a longer path to travel between the layered structures 121 in the second annular portion 123. In this embodiment, N4>N3. This increases the layered structure 121 connected to the second portion W22 and reduces the amount of electrons traveling between the layered structures 121 in the second annular portion 123, thereby shortening the second current path and further reducing the difference between the first current path and the second current path. This improves the uniformity of current density, reduces internal resistance, and enhances current flow capacity.

[0182] In some embodiments, M consecutive layer structures 121 among all the layer structures 121 are welded to the current collecting member 50 to form a second welding portion W2 , where 1 / 3≤M / N≤1 / 2, M≥2, and M is a positive integer.

[0183] Optionally, M=N3+N4.

[0184] As the value of M / N increases, the internal resistance of the first electrode tab 12 decreases, the area of ​​the second weld portion W2 increases, and the current flow capacity between the first electrode tab 12 and the current collecting member 50 increases. However, when the area of ​​the current collecting member 50 remains constant, as the value of M / N increases, the area of ​​the first weld portion W1 decreases, and the current flow capacity between the current collecting member 50 and the end cap 30 decreases.

[0185] After experiments, the inventors have limited the value of M / N to 1 / 3-1 / 2 to balance the flow capacity between the first electrode 12 and the current collecting member 50 and the flow capacity between the current collecting member 50 and the end cover 30 , thereby optimizing the flow capacity of the battery cell 7 .

[0186] In some embodiments, there are multiple second welding portions W2, and the multiple second welding portions W2 are spaced apart along the circumference of the first electrode tab 12. Of course, the present application is not limited thereto, and in other embodiments, there may be only one second welding portion W2, for example, the second welding portion W2 may be annular, spiral, or linear.

[0187] In some embodiments, the end cap 30 includes a cap body 31 and a first protrusion 32 protruding from an inner surface 311 of the cap body in a direction facing the first electrode tab 12 .

[0188] The cover body 31 is a plate-like structure having an inner surface and an outer surface oppositely disposed along the thickness direction Z. The inner surface 311 of the cover body faces the electrode assembly 10. Optionally, the inner surface 311 and the outer surface 312 of the cover body are both planar and parallel.

[0189] The first protrusion 32 protrudes relative to the inner surface 311 of the cover body in a direction facing the electrode assembly 10, so that at least a portion of the first protrusion 32 protrudes from the inner surface 311 of the cover body. This embodiment does not limit the extent to which the first protrusion 32 protrudes from the inner surface 311 of the cover body.

[0190] The first protrusion 32 is connected to the cover body 31. Exemplarily, the first protrusion 32 is an annular structure surrounding the outside of the cover body 31. Of course, alternatively, the cover body 31 can also surround the outside of the first protrusion 32.

[0191] The current collecting member 50 may be welded to the first protrusion 32 or to the cover body 31 , and this embodiment does not limit this.

[0192] In some embodiments, the end cover 30 includes a cover body 31 and a first protrusion 32 protruding from the inner surface 311 of the cover body in a direction facing the first pole ear 12. The first protrusion 32 is used to abut and weld with the current collecting component 50 to form a first welding portion W1, and to form a first avoidance gap G1 between the current collecting component 50 and the cover body 31 for avoiding the second welding portion W2.

[0193] The top end surface of the first protrusion 32 presses and supports the current collecting member 50 to at least space the cover body 31 and the current collecting member 50 apart in the thickness direction Z.

[0194] The projection of the second welding portion W2 along the thickness direction Z at least partially overlaps with the projection of the cover body 31 along the thickness direction Z. Optionally, the projection of the second welding portion W2 along the thickness direction Z is located within the projection of the cover body 31 along the thickness direction Z.

[0195] In this embodiment, a first clearance gap G1 is provided to avoid the second weld portion W2, thereby preventing the second weld portion W2 from abutting the cover body 31 and reducing the risk of the second weld portion W2 crushing the cover body 31. If the second weld portion W2 abuts the cover body 31, over-alignment will occur between the end cap 30 and the current collecting member 50, causing the second weld portion W2 to interfere with the abutment between the first protrusion 32 and the current collecting member 50. By providing the first clearance gap G1 in this embodiment, the second weld portion W2 is prevented from interfering with the abutment between the first protrusion 32 and the current collecting member 50, thereby ensuring the connection strength between the first protrusion 32 and the current collecting member 50.

[0196] In some embodiments, a first recess 33 is formed on the end cap 30 at a position corresponding to the first protrusion 32 , the first recess 33 being recessed from the outer surface 312 of the cap body in a direction facing the electrode assembly 10 .

[0197] When assembling the end cap 30 and the current collecting member 50, a laser can be applied to the bottom surface of the first recess 33 to weld the first protrusion 32 to the current collecting member 50 from the outside. In this embodiment, the provision of the first recess 33 reduces the thickness of the first protrusion 32. This reduces the welding power required to weld the first protrusion 32 to the current collecting member 50, reduces heat generation, and reduces the risk of burning other components.

[0198] The first protrusion 32 is a solid structure with a certain thickness; for example, the first protrusion 32 is a thin-walled structure. The first concave portion 33 is a cavity without a solid structure.

[0199] The first recess 33 can reduce the strength of the first protrusion 32 and improve the elastic deformation ability of the first protrusion 32. In this way, when the first protrusion 32 is pressed against the current collecting component 50, the first protrusion 32 can release stress through deformation, reduce the impact force, and reduce the risk of the current collecting component 50 and the first electrode tab 12 being crushed.

[0200] In some embodiments, the bottom surface of the first recess 33 is closer to the first tab 12 than the inner surface 311 of the cover body.

[0201] The first concave portion 33 and the first convex portion 32 can be formed by stamping the end cap 30. The greater the depth of the first concave portion 33 along the thickness direction Z, the greater the extent to which the first convex portion 32 protrudes from the inner surface 311 of the cap body, and the larger the first avoidance gap G1.

[0202] The embodiment of the present application ensures that the first protrusion 32 protrudes beyond the inner surface 311 of the cover body, thereby more effectively supporting the current collecting member 50 and reducing the risk of contact between the second weld portion W2 and the end cover 30. Furthermore, while ensuring the protrusion of the first protrusion 32, the embodiment of the present application further ensures the recessed degree of the first recessed portion 33, thereby improving the elastic deformation capability of the first protrusion 32 and reducing the risk of the first protrusion 32 crushing the current collecting member 50 and the first tab 12 during assembly.

[0203] In some embodiments, the cover body 31 surrounds the outer side of the first protrusion 32 , and the first welding portion W1 is disposed on the inner side of the second welding portion W2 .

[0204] In this embodiment, both the inside and the outside are positions relative to the central axis X. The first protrusion 32 is closer to the central axis X than the cover body 31 , and the first welding portion W1 is closer to the central axis X than the second welding portion W2 .

[0205] In some embodiments, a first recess 33 is formed on the end cap 30 at a position corresponding to the first protrusion 32, which is recessed from the outer surface 312 of the cap body in a direction facing the electrode assembly 10. A groove 34 is provided on the bottom surface of the first recess 33, and the bottom of the groove 34 is used for welding to the current collecting member 50 to form a first weld W1.

[0206] The groove 34 is recessed from the bottom surface of the first concave portion 33 in a direction facing the electrode assembly 10. A portion of the first convex portion 32 located between the bottom surface of the groove 34 and the top surface of the first convex portion 32 forms a connecting portion for welding with the current collecting member 50 to form a first weld W1.

[0207] In this embodiment, the thickness of the connecting portion of the first protrusion 32 is reduced by providing the first concave portion 33 and the groove 34 , which can reduce the welding power required for welding the connecting portion to the current collecting component 50 , reduce heat generation, and reduce the risk of burning other components (such as the isolation member).

[0208] In some embodiments, the end cap 30 further includes a second protrusion 35 surrounding the outer side of the cap body 31 . The second protrusion 35 protrudes from the inner surface 311 of the cap body in a direction facing the first electrode tab 12 . The second protrusion 35 is used to support the first electrode tab 12 .

[0209] The second protrusion 35 is an annular structure surrounding the outer side of the cover body 31. In the radial direction, the second protrusion 35 is closer to the side wall 22 than the cover body 31.

[0210] The second protrusion 35 may directly support the first electrode tab 12 or support the first electrode tab 12 through other components (eg, the current collecting component 50 ).

[0211] In this embodiment, the second protrusion 35 can support the first electrode tab 12 to reduce the shaking amplitude of the electrode assembly 10 when the battery cell 7 vibrates, thereby improving the stability of the electrode assembly 10 .

[0212] In some embodiments, the second protrusion 35 directly abuts against and supports the first electrode tab 12 .

[0213] In some embodiments, the second protrusion 35 is spaced apart from the current collecting member 50 to prevent the second protrusion 35 from interfering with the contact between the current collecting member 50 and the first protrusion 32 , thereby ensuring that the first protrusion 32 is in close contact with the current collecting member 50 .

[0214] Optionally, the second protrusion 35 surrounds the outer side of the current collecting member 50 .

[0215] In some embodiments, the outer side surface 351 of the second protrusion abuts against the inner surface of the housing 20 and is used to be welded to the housing 20 to close the opening 21 .

[0216] The outer side surface 351 of the second protrusion is the surface of the second protrusion 35 facing the side wall 22 of the housing 20. The outer side surface 351 of the second protrusion is a cylindrical surface. Optionally, the outer side surface 351 of the second protrusion is a cylindrical surface.

[0217] The portion of the second protrusion 35 extending into the housing 20 may have an interference fit, a transition fit, or a clearance fit with the housing 20. Optionally, the portion of the second protrusion 35 extending into the housing 20 may have an interference fit with the housing 20. The interference fit may increase the connection strength between the housing 20 and the end cover 30 and improve the sealing performance.

[0218] Optionally, the second protrusion 35 and the sidewall 22 of the housing 20 are connected by laser welding. During welding, a laser is irradiated at the junction of the second protrusion 35 and the sidewall 22, melting and connecting at least a portion of the outer side surface 351 of the second protrusion and a portion of the inner surface of the housing 20. The outer side surface 351 of the second protrusion abuts the inner surface of the housing 20, thereby reducing the risk of laser light entering the interior of the housing 20 and burning the electrode assembly 10.

[0219] Alternatively, the laser may be irradiated onto the outer surface of the side wall 22 facing away from the second protrusion 35 .

[0220] In this embodiment, welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and flow capacity between the second protrusion 35 and the housing 20.

[0221] In some embodiments, a second recess 36 is formed on the end cap 30 at a position corresponding to the second protrusion 35 , the second recess 36 being recessed from the outer surface 312 of the cap body in a direction facing the electrode assembly 10 .

[0222] The second recess 36 can reduce the strength of the second protrusion 35 and improve the elasticity of the second protrusion 35. In this way, during the welding process of the second protrusion 35 and the shell 20, the second protrusion 35 can release the welding stress through deformation, thereby reducing the risk of deformation and cracking in the welding area and improving the sealing performance.

[0223] In some embodiments, the bottom surface of the second recess 36 is closer to the first tab 12 than the inner surface 311 of the cover body.

[0224] The second recess 36 and the second protrusion 35 can be formed by stamping the end cap 30. The greater the depth of the second recess 36 in the thickness direction Z, the greater the extent to which the second protrusion 35 protrudes from the inner surface 311 of the cap body.

[0225] The embodiment of the present application can ensure that the second protrusion 35 protrudes beyond the inner surface 311 of the cover body to support the first electrode tab 12. At the same time, while ensuring the protrusion of the second protrusion 35, the embodiment of the present application further ensures the concavity of the second concave portion 36 to improve the elasticity of the second protrusion 35, allowing the second protrusion 35 to release welding stress through deformation.

[0226] In some embodiments, the cover body 31 is provided with a weak portion V, which is configured to rupture when the internal pressure of the battery cell 7 reaches a threshold value to release the internal pressure.

[0227] The threshold value may be designed to vary depending on the design requirements and may depend on one or more materials of the positive electrode sheet, the negative electrode sheet, the electrolyte, and the separator in the battery cell 7 .

[0228] After the weak portion V ruptures, a channel is formed for internal pressure relief. After the weak portion V ruptures, the high-temperature, high-pressure substances within the battery cell 7 are discharged from the ruptured area as emissions. In this way, the battery cell 7 can be depressurized under controllable pressure, thereby avoiding potentially more serious accidents. The emissions from the battery cell 7 mentioned in this application include but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, separator fragments, high-temperature, high-pressure gases generated by the reaction, flames, etc.

[0229] This embodiment provides a weak portion V on the cover body 31 to release internal pressure in the event of thermal runaway of the battery cell 7, thereby improving safety. A first clearance gap G1 is formed between the current collecting member 50 and the cover body 31 to reduce the risk of the current collecting member 50 blocking the exhaust passage in the event of a rupture of the weak portion V, ensuring smooth exhaust and minimizing safety risks.

[0230] In some embodiments, the current collecting member 50 is a flat plate. A flat current collecting member 50 is easier to form. The flat current collecting member 50 can be in full contact with the first electrode tab 12, thereby increasing the flow area and providing more uniform support for the first electrode tab 12. This reduces the risk of displacement or misalignment of the electrode sheets of the electrode assembly 10 in the thickness direction Z. The flat current collecting member 50 can also be in close contact with the first protrusion 32, reducing the risk of microcracks forming on the first protrusion 32 during welding and improving sealing and safety.

[0231] In some embodiments, the first protrusion 32 supports the first electrode tab 12 via the current collecting member 50 .

[0232] In this embodiment, the first protrusion 32 supports the first electrode tab 12 via the current collecting member 50, thereby reducing the amplitude of shaking of the electrode assembly 10 when the battery cell 7 vibrates, thereby improving the stability of the electrode assembly 10. The current collecting member 50 can support the electrode assembly 10 via the first electrode tab 12, thereby reducing the risk of displacement or misalignment of the electrode sheets of the electrode assembly 10 in the thickness direction Z.

[0233] The first protrusion 32 supports the middle area of ​​the first pole tab 12 through the current collecting component 50, and the second protrusion 35 supports the edge area of ​​the first pole tab 12. This can improve the uniformity of the force applied to the first pole tab 12 and reduce the risk of the pole piece of the electrode assembly 10 being offset or misaligned in the thickness direction Z.

[0234] Figure 9 Schematic cross-sectional views of battery cells provided in other embodiments of the present application; Figure 10 A schematic cross-sectional view of a battery cell provided in some other embodiments of the present application; Figure 11 for Figure 10 An enlarged schematic diagram of a battery cell at circle B is shown.

[0235] like Figure 9 As shown, in some embodiments, the first protrusion 32 surrounds the outer side of the cover body 31 , and the first welding portion W1 is disposed on the outer side of the second welding portion W2 .

[0236] In this embodiment, the outer side refers to a position relative to the central axis X. The cover body 31 is closer to the central axis X than the first protrusion 32 , and the second welding portion W2 is closer to the central axis X than the first welding portion W1 .

[0237] In some embodiments, the outer side surface 321 of the first protrusion abuts against the inner surface of the housing 20 and is used to be welded to the housing 20 to close the opening.

[0238] The outer side surface 321 of the first protrusion is the surface of the first protrusion 32 facing the side wall 22 of the housing 20. The outer side surface 321 of the first protrusion is a cylindrical surface. Optionally, the outer side surface 321 of the first protrusion is a cylindrical surface.

[0239] The portion of the first protrusion 32 extending into the housing 20 may have an interference fit, a transition fit, or a clearance fit with the housing 20. Optionally, the portion of the first protrusion 32 extending into the housing 20 may have an interference fit with the housing 20. The interference fit may increase the connection strength between the housing 20 and the end cover 30 and improve the sealing performance.

[0240] Optionally, the first protrusion 32 and the sidewall 22 of the housing 20 are connected by laser welding. During welding, a laser is irradiated at the junction of the first protrusion 32 and the sidewall 22, melting and connecting at least a portion of the outer side surface 321 of the first protrusion and a portion of the inner surface of the housing 20. The outer side surface 321 of the first protrusion abuts the inner surface of the housing 20, thereby reducing the risk of laser light entering the interior of the housing 20 and burning the electrode assembly 10.

[0241] Alternatively, the laser may be irradiated onto the outer surface of the side wall 22 facing away from the first protrusion 32 .

[0242] In this embodiment, welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and flow capacity between the housing 20 and the first protrusion 32.

[0243] like Figure 10 and Figure 11 As shown, in some embodiments, the end cap 30 further includes an extension portion 37 surrounding the outer side of the first protrusion 32 , and the surface of the extension portion 37 facing the first tab 12 abuts against and is welded to the end surface 24 of the housing 20 surrounding the opening 21 to close the opening 21 .

[0244] The extension portion 37 includes an inner surface and an outer surface disposed opposite to each other along the thickness direction Z. The inner surface of the extension portion 37 faces the first electrode tab 12. Optionally, the extension portion 37 is an annular plate structure, and both the inner surface and the outer surface of the extension portion 37 are plane.

[0245] The extension portion 37 and the housing 20 are arranged along the thickness direction Z, and the inner surface of the extension portion 37 may be disposed parallel to the end surface 24 of the housing 20 .

[0246] Optionally, during welding, the laser is irradiated at the junction of the end face 24 of the shell 20 and the inner surface of the extension portion 37; after welding, at least part of the inner surface of the extension portion 37 and at least part of the end face 24 of the shell 20 are melted and connected together.

[0247] In this embodiment, when assembling the end cap 30 and the shell 20, the end surface 24 of the shell 20 can play a limiting role in the thickness direction Z, reducing the risk of the end cap 30 being over-inserted into the shell 20 and improving assembly efficiency.

[0248] In some embodiments, the end cap 30 further includes a second protrusion 35. The cap body 31 surrounds the outer side of the second protrusion 35. The second protrusion 35 protrudes from the inner surface 311 of the cap body in a direction facing the first electrode tab 12. A second recess 36 is formed on the end cap 30 at a position corresponding to the second protrusion 35 and is recessed from the outer surface 312 of the cap body in a direction facing the electrode assembly 10.

[0249] The second protrusion 35 and the second recess 36 may be formed by stamping the end cover 30 .

[0250] During normal cycling, the battery cell 7 may release a small amount of gas, which can increase the internal pressure of the battery cell 7 and thus create a risk of deformation of the end cap 30. This embodiment provides a second protrusion 35 and a second recess 36 in the middle portion of the end cap 30 to increase the strength of the end cap 30 and reduce deformation of the end cap 30.

[0251] In some embodiments, a region of the second convex portion 35 opposite to the bottom surface of the second concave portion 36 is provided with a weak portion V, which is configured to rupture when the internal pressure of the battery cell 7 reaches a threshold value to release the internal pressure.

[0252] This embodiment provides a weak portion V on the second protrusion 35 to release internal pressure in the event of thermal runaway of the battery cell 7, thereby improving safety. The weak portion V is formed in the area of ​​the second protrusion 35 that faces the bottom of the second recess 36. This increases the distance between the weak portion V and other external components, reducing the risk of damage from external components.

[0253] In some embodiments, a second avoiding gap G2 is formed between the second protrusion 35 and the current collecting member 50 .

[0254] The first protrusion 32 protrudes from the inner surface 311 of the cover body to a greater extent than the second protrusion 35 . In this way, the first protrusion 32 can support the current collecting member 50 to form a second escape gap G2 between the second protrusion 35 and the current collecting member 50 .

[0255] In this embodiment, a second avoidance gap G2 is formed between the second protrusion 35 and the current collecting member 50 to reduce the risk of the current collecting member 50 blocking the exhaust channel when the weak portion V ruptures, thereby ensuring smooth exhaust and reducing safety risks.

[0256] Figure 12 Schematic cross-sectional views of battery cells provided in some further embodiments of the present application, Figure 13 for Figure 12 An enlarged schematic diagram of a battery cell at box C is shown.

[0257] like Figure 12 and Figure 13 As shown, in some embodiments, the current collecting component 50 includes: a first current collecting portion 51, which is used to abut and weld with the end cover 30 to form a first welding portion W1; a second current collecting portion 52, which is used to abut and weld with the first electrode tab 12 to form a second welding portion W2, and the second current collecting portion 52 is protruding from the surface of the first current collecting portion 51 facing the electrode assembly 10, and the second current collecting portion 52 is provided with an avoidance recess 53 on the side away from the electrode assembly 10, and the avoidance recess 53 is used to avoid the second welding portion W2.

[0258] The end cover 30 may be in the shape of a flat plate or other shapes.

[0259] In this embodiment, a relief recess 53 is provided for circumventing the second weld portion W2 to prevent the second weld portion W2 from interfering with the abutment between the first current collecting portion 51 and the end cap 30, thereby ensuring the connection strength between the first current collecting portion 51 and the end cap 30 and reducing the risk of the second weld portion W2 crushing the end cap 30. The relief recess 53 can reduce the thickness of the second current collecting portion 52, thereby reducing the welding power required for welding the second current collecting portion 52 to the first electrode tab 12, reducing heat generation, and reducing the risk of burning other components (such as the separator).

[0260] In some embodiments, the first collecting portion 51 is a flat plate structure surrounding the outer side of the second collecting portion 52 .

[0261] In some embodiments, the end cover 30 includes: a cover body 31, which is used to be welded with the first collecting portion 51 to form a first welding portion W1; and a first protrusion 32, which surrounds the outside of the cover body 31 and protrudes from the inner surface of the cover body in a direction facing the first pole ear 12. The first protrusion 32 is used to abut against the first pole ear 12 to support the first pole ear 12.

[0262] In this embodiment, the second collecting portion 52 supports the middle area of ​​the first pole ear 12, and the first protrusion 32 supports the edge area of ​​the first pole ear 12. This can improve the uniformity of the force applied to the first pole ear 12 and reduce the risk of the pole piece of the electrode assembly 10 being offset or misaligned in the thickness direction Z.

[0263] In some embodiments, a first recess 33 is formed on the end cover 30 at a position corresponding to the first protrusion 32, which is recessed from the outer surface of the cover body in a direction facing the electrode assembly 10, and the bottom surface of the first recess 33 is closer to the first electrode tab 12 than the inner surface of the cover body.

[0264] The first concave portion 33 and the first convex portion 32 can be formed by stamping the end cap 30. The greater the depth of the first concave portion 33 along the thickness direction Z, the greater the extent to which the first convex portion 32 protrudes from the inner surface of the cap body.

[0265] The embodiment of the present application can ensure that the first protrusion 32 protrudes beyond the inner surface of the cover body to support the first tab 12. At the same time, while ensuring the protrusion of the first protrusion 32, the embodiment of the present application further ensures the depression of the first recess 33, thereby improving the elasticity of the first protrusion 32, reducing the impact force when the first protrusion 32 is pressed against the first tab 12, and reducing the risk of the first tab 12 being crushed.

[0266] In some embodiments, the outer side surface of the first protrusion abuts against the inner surface of the housing 20 and is used to be welded to the housing 20 to close the opening 21 .

[0267] The outer side surface of the first protrusion is the surface of the first protrusion 32 facing the side wall 22 of the housing 20. The outer side surface of the first protrusion is a cylindrical surface, and optionally, the outer side surface of the first protrusion is a cylindrical surface.

[0268] The portion of the first protrusion 32 extending into the housing 20 may have an interference fit, a transition fit, or a clearance fit with the housing 20. Optionally, the portion of the first protrusion 32 extending into the housing 20 may have an interference fit with the housing 20. The interference fit may increase the connection strength between the housing 20 and the end cover 30 and improve the sealing performance.

[0269] Optionally, the first protrusion 32 and the sidewall 22 of the housing 20 are connected by laser welding. During welding, a laser is irradiated at the junction of the first protrusion 32 and the sidewall 22, melting and connecting at least a portion of the outer side surface 321 of the first protrusion and a portion of the inner surface of the housing 20. The outer side surface of the first protrusion abuts the inner surface of the housing 20, thereby reducing the risk of laser light entering the interior of the housing 20 and burning the electrode assembly 10.

[0270] Alternatively, the laser may be irradiated onto the outer surface of the side wall 22 facing away from the first protrusion 32 .

[0271] In this embodiment, welding can achieve sealing, reduce the risk of electrolyte leakage, and improve the connection strength and flow capacity between the first protrusion 32 and the housing 20.

[0272] In some embodiments, the end cap 30 further includes a second protrusion 35. The cap body 31 surrounds the outer side of the second protrusion 35. The second protrusion 35 protrudes from the inner surface 311 of the cap body in a direction facing the first electrode tab 12 and extends into the avoidance recess 53. A second recess 36 is formed on the end cap 30 at a position corresponding to the second protrusion 35 and is recessed from the outer surface of the cap body in a direction facing the electrode assembly 10.

[0273] The second protrusion 35 and the second recess 36 may be formed by stamping the end cover 30 .

[0274] During normal cycling, the battery cell 7 may release a small amount of gas, which can increase the internal pressure of the battery cell 7 and thus create a risk of deformation of the end cap 30. This embodiment provides a second protrusion 35 and a second recess 36 in the middle portion of the end cap 30 to increase the strength of the end cap 30 and reduce deformation of the end cap 30.

[0275] In some embodiments, a weak portion V is provided in the area of ​​the second protrusion 35 opposite the bottom surface of the second recess 36. The weak portion V is configured to rupture when the internal pressure of the battery cell 7 reaches a threshold value to release the internal pressure. The relief recess 53 also serves to separate the second current collecting portion 52 from the weak portion V.

[0276] This embodiment provides a weak portion V on the second protrusion 35 to release internal pressure in the event of thermal runaway of the battery cell 7, thereby improving safety. The weak portion V is formed in the area of ​​the second protrusion 35 that faces the bottom of the second recess 36. This increases the distance between the weak portion V and other external components, reducing the risk of damage from external components.

[0277] The avoidance recess 53 of this embodiment can reduce the risk of the flow collecting component 50 blocking the exhaust passage when the weak portion V ruptures, thereby ensuring smooth exhaust and reducing safety risks.

[0278] In some embodiments, the end cap 30 further includes an extension portion (not shown) surrounding the outer side of the first protrusion, and a surface of the extension portion facing the first tab abuts against and is welded to an end surface of the housing surrounding the opening to close the opening.

[0279] Figure 14 A schematic flow chart of a method for manufacturing a battery cell provided in some embodiments of the present application.

[0280] like Figure 14 As shown, the manufacturing method of the battery cell of the embodiment of the present application includes:

[0281] S100, providing an electrode assembly, wherein the electrode assembly has a first electrode tab;

[0282] S200, providing a current collecting component, and welding the current collecting component to the first electrode tab;

[0283] S300, providing a housing, wherein the housing has an opening;

[0284] S400, installing the electrode assembly and the current collecting member into the housing, with the first electrode tab located at one end of the electrode assembly facing the opening;

[0285] S500, providing an end cover, and closing the end cover on the opening, so that the electrode assembly is sealed in the housing, and the current collecting member is disposed between the end cover and the first electrode tab;

[0286] S600: Weld the end cap and the current collecting member to achieve electrical connection between the end cap and the first electrode tab.

[0287] It should be noted that the relevant structure of the battery cell manufactured by the above-mentioned method for manufacturing the battery cell can refer to the battery cells provided in the above-mentioned embodiments.

[0288] When assembling a battery cell based on the above-mentioned battery cell manufacturing method, it is not necessary to follow the above-mentioned steps in sequence. In other words, the steps can be performed in the order mentioned in the embodiment, or in a different order than the order mentioned in the embodiment, or several steps can be performed simultaneously. For example, steps S100 and S300 can be performed in any order and can be performed simultaneously.

[0289] Figure 15 A schematic block diagram of a battery cell manufacturing system provided in some embodiments of the present application.

[0290] like Figure 15 As shown, the embodiment of the present application further provides a battery cell manufacturing system 90 including:

[0291] A first providing device 91 is used to provide an electrode assembly, wherein the electrode assembly has a first electrode tab;

[0292] A second providing device 92 is used to provide a current collecting component and weld the current collecting component to the first electrode tab;

[0293] A third providing device 93 is used to provide a housing having an opening;

[0294] A first assembly device 94 is used to install the electrode assembly and the current collecting member into the housing, with the first electrode tab positioned at an end of the electrode assembly facing the opening;

[0295] A fourth providing device 95 is used to provide an end cap and cover the opening with the end cap so that the electrode assembly is sealed in the housing and the current collecting member is disposed between the end cap and the first electrode tab;

[0296] The second assembly device 96 is used to weld the end cover and the current collecting member to achieve electrical connection between the end cover and the first electrode tab.

[0297] The relevant structures of the battery cells manufactured by the above manufacturing system can refer to the battery cells provided in the above embodiments.

[0298] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0299] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, characterized in that: include: a housing having an opening; an electrode assembly housed in the housing, the electrode assembly having a first tab at one end facing the opening, the electrode assembly being a wound structure; an end cap, used to cover the opening to seal the electrode assembly in the housing; a current collecting member disposed between the end cover and the first electrode tab, wherein a portion of the current collecting member is used to abut against and weld with the end cover to form a first welding portion, and another portion of the current collecting member is used to abut against and weld with the first electrode tab to form a second welding portion; In which, the end cover includes a cover body and a first convex portion protruding from the inner surface of the cover body in a direction facing the first electrode tab, the first convex portion is used to abut and weld with the current collecting component to form the first welding portion, and form a first avoidance gap between the current collecting component and the cover body for avoiding the second welding portion, the end cover also includes a second convex portion, the cover body surrounds the outside of the second convex portion, the second convex portion protrudes from the inner surface of the cover body in a direction facing the first electrode tab, and a second recessed portion that is recessed from the outer surface of the cover body in a direction facing the electrode assembly is formed at a position on the end cover corresponding to the second convex portion.

2. The battery cell according to claim 1, wherein: A projection of the first welding portion along the thickness direction of the end cover and a projection of the second welding portion along the thickness direction of the end cover do not overlap.

3. The battery cell according to claim 2, characterized in that: The electrode assembly is wound along a central axis to form a first electrode tab, wherein the first electrode tab includes N layer structures arranged around the central axis, and an extending direction of the central axis is parallel to a thickness direction of the end cap; The first tab is composed of a first annular portion and a second annular portion surrounding the first annular portion, the number of layer structures in the first annular portion is N1, the number of layer structures in the second annular portion is N2, N=N1+N2, the value of |N1-N2| is less than or equal to 2, and N1 and N2 are positive integers; The first annular portion is welded to the current collecting member to form a first portion, the second annular portion is welded to the current collecting member to form a second portion connected to the first portion, and the second welded portion is composed of the first portion and the second portion.

4. The battery cell according to claim 3, characterized in that N3 continuous layer structures in the first annular portion arranged near the second annular portion are welded to the current collecting component to form the first part, and N4 continuous layer structures in the second annular portion arranged near the first annular portion are welded to the current collecting component to form the second part. The N3 continuous layer structures are continuously arranged with the N4 continuous layer structures, N4>N3≥1, and N3 and N4 are positive integers.

5. The battery cell according to claim 3 or 4, characterized in that: M continuous layer structures among all the layer structures are welded to the current collecting member to form the second welding portion, wherein 1 / 3≤M / N≤1 / 2, M≥2, and M is a positive integer.

6. The battery cell according to any one of claims 1 to 4, characterized in that: A first recessed portion is formed on the end cover at a position corresponding to the first protrusion and is recessed from the outer surface of the cover body in a direction facing the electrode assembly. The bottom surface of the first recessed portion is closer to the first tab than the inner surface of the cover body.

7. The battery cell according to any one of claims 1 to 4, characterized in that: The first protrusion surrounds the outer side of the cover body, and the first welding portion is arranged on the outer side of the second welding portion.

8. The battery cell according to claim 7, characterized in that The outer side surface of the first protrusion abuts against the inner surface of the shell and is used for welding with the shell to close the opening.

9. The battery cell according to claim 7, characterized in that: The end cover further includes an extension portion surrounding the outer side of the first protrusion, and a surface of the extension portion facing the first tab abuts against and is welded to an end surface of the housing surrounding the opening to close the opening.

10. The battery cell according to claim 1, characterized in that A weak portion is provided in a region of the second convex portion opposite to a bottom surface of the second concave portion, and the weak portion is configured to rupture when the internal pressure of the battery cell reaches a threshold value to release the internal pressure.

11. The battery cell according to claim 10, characterized in that A second escape gap is formed between the second protrusion and the current collecting member.

12. The battery cell according to any one of claims 1 to 4, characterized in that: The cover body surrounds the outer side of the first protrusion, and the first welding portion is arranged on the inner side of the second welding portion.

13. The battery cell according to claim 12, characterized in that: A first recessed portion is formed on the end cap at a position corresponding to the first protrusion and is recessed from the outer surface of the cap body in a direction facing the electrode assembly; A groove is formed on the bottom surface of the first recess, and the bottom of the groove is used for welding with the current collecting member to form the first welding portion.

14. The battery cell according to any one of claims 1 to 4, characterized in that: The current collecting component is a flat plate structure.

15. The battery cell according to any one of claims 1 to 4, characterized in that: The first protrusion supports the first electrode tab via the current collecting member.

16. The battery cell according to any one of claims 1 to 4, characterized in that: The current collecting component comprises: a first collecting portion, configured to abut against and weld with the end cover to form the first welding portion; The second current collecting portion is used to abut and weld with the first electrode tab to form the second welding portion. The second current collecting portion is protruding from the surface of the first current collecting portion facing the electrode assembly, and the second current collecting portion is provided with an avoidance recess on the side away from the electrode assembly, and the avoidance recess is used to avoid the second welding portion.

17. The battery cell according to any one of claims 1 to 4, characterized in that: The end cover is used to electrically connect the first tab and the housing.

18. The battery cell according to claim 17, characterized in that The housing further includes a side wall and a bottom wall connected to the side wall, wherein the side wall extends along the thickness direction of the end cover and is arranged around the outer periphery of the electrode assembly, and the bottom wall is provided with an electrode lead-out hole; The electrode assembly further includes a second electrode tab, wherein the first electrode tab and the second electrode tab have opposite polarities and are respectively located at two ends of the electrode assembly; The battery cell further includes an electrode terminal installed in the electrode lead-out hole, and the electrode terminal is electrically connected to the second electrode tab.

19. The battery cell according to claim 18, characterized in that The bottom wall and the side wall are integrally formed.

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

21. The battery cell according to any one of claims 1 to 4, characterized in that: The base material of the shell is the same as the base material of the end cover.

22. The battery cell according to any one of claims 1 to 4, characterized in that: The battery cell is a cylindrical battery cell.

23. A battery cell, characterized in that: include: a housing having an opening; an electrode assembly housed in the housing, the electrode assembly having a first tab at one end facing the opening, the electrode assembly being a wound structure; an end cap, used to cover the opening to seal the electrode assembly in the housing; a current collecting member disposed between the end cover and the first electrode tab, wherein a portion of the current collecting member is used to abut against and weld with the end cover to form a first welding portion, and another portion of the current collecting member is used to abut against and weld with the first electrode tab to form a second welding portion; In which, the end cover includes a cover body and a first convex portion protruding from the inner surface of the cover body in a direction facing the first pole ear, the first convex portion is used to abut and weld with the current collecting component to form the first welding portion, and to form a first avoidance gap between the current collecting component and the cover body for avoiding the second welding portion, the end cover also includes a second convex portion surrounding the outer side of the cover body, the second convex portion protruding from the inner surface of the cover body in a direction facing the first pole ear, and the second convex portion is used to support the first pole ear.

24. The battery cell according to claim 23, characterized in that A projection of the first welding portion along the thickness direction of the end cover and a projection of the second welding portion along the thickness direction of the end cover do not overlap.

25. The battery cell according to claim 24, characterized in that The electrode assembly is wound along a central axis to form a first electrode tab, wherein the first electrode tab includes N layer structures arranged around the central axis, and an extending direction of the central axis is parallel to a thickness direction of the end cap; The first tab is composed of a first annular portion and a second annular portion surrounding the first annular portion, the number of layer structures in the first annular portion is N1, the number of layer structures in the second annular portion is N2, N=N1+N2, the value of |N1-N2| is less than or equal to 2, and N1 and N2 are positive integers; The first annular portion is welded to the current collecting member to form a first portion, the second annular portion is welded to the current collecting member to form a second portion connected to the first portion, and the second welded portion is composed of the first portion and the second portion.

26. The battery cell according to claim 25, characterized in that N3 continuous layer structures in the first annular portion arranged near the second annular portion are welded to the current collecting component to form the first part, and N4 continuous layer structures in the second annular portion arranged near the first annular portion are welded to the current collecting component to form the second part. The N3 continuous layer structures are continuously arranged with the N4 continuous layer structures, N4>N3≥1, and N3 and N4 are positive integers.

27. The battery cell according to claim 25 or 26, characterized in that: M continuous layer structures among all the layer structures are welded to the current collecting member to form the second welding portion, wherein 1 / 3≤M / N≤1 / 2, M≥2, and M is a positive integer.

28. The battery cell according to any one of claims 23 to 26, characterized in that: A first recessed portion is formed on the end cover at a position corresponding to the first protrusion and is recessed from the outer surface of the cover body in a direction facing the electrode assembly. The bottom surface of the first recessed portion is closer to the first tab than the inner surface of the cover body.

29. The battery cell according to any one of claims 23 to 26, characterized in that: The cover body surrounds the outer side of the first protrusion, and the first welding portion is arranged on the inner side of the second welding portion.

30. The battery cell according to claim 29, characterized in that A first recessed portion is formed on the end cap at a position corresponding to the first protrusion and is recessed from the outer surface of the cap body in a direction facing the electrode assembly; A groove is formed on the bottom surface of the first recess, and the bottom of the groove is used for welding with the current collecting member to form the first welding portion.

31. The battery cell according to claim 23, characterized in that The outer side surface of the second protrusion abuts against the inner surface of the shell and is used for welding with the shell to close the opening.

32. The battery cell according to claim 23, characterized in that A second recessed portion is formed on the end cover at a position corresponding to the second protrusion, which is recessed from the outer surface of the cover body in a direction facing the electrode assembly. The bottom surface of the second recessed portion is closer to the first tab than the inner surface of the cover body.

33. The battery cell according to claim 23, characterized in that The cover body is provided with a weak portion configured to rupture when internal pressure of the battery cell reaches a threshold value to release the internal pressure.

34. The battery cell according to any one of claims 23 to 26, characterized in that: The current collecting component is a flat plate structure.

35. The battery cell according to any one of claims 23 to 26, characterized in that: The first protrusion supports the first electrode tab via the current collecting member.

36. The battery cell according to any one of claims 23 to 26, characterized in that: The current collecting component comprises: a first collecting portion, configured to abut against and weld with the end cover to form the first welding portion; The second current collecting portion is used to abut and weld with the first electrode tab to form the second welding portion. The second current collecting portion is protruding from the surface of the first current collecting portion facing the electrode assembly, and the second current collecting portion is provided with an avoidance recess on the side away from the electrode assembly, and the avoidance recess is used to avoid the second welding portion.

37. The battery cell according to any one of claims 23 to 26, characterized in that: The end cover is used to electrically connect the first tab and the housing.

38. The battery cell according to claim 37, characterized in that The housing further includes a side wall and a bottom wall connected to the side wall, wherein the side wall extends along the thickness direction of the end cover and is arranged around the outer periphery of the electrode assembly, and the bottom wall is provided with an electrode lead-out hole; The electrode assembly further includes a second electrode tab, wherein the first electrode tab and the second electrode tab have opposite polarities and are respectively located at two ends of the electrode assembly; The battery cell further includes an electrode terminal installed in the electrode lead-out hole, and the electrode terminal is electrically connected to the second electrode tab.

39. The battery cell according to claim 38, characterized in that The bottom wall and the side wall are integrally formed.

40. The battery cell according to claim 37, wherein: The first electrode tab is a negative electrode tab, and the base material of the shell is steel.

41. The battery cell according to any one of claims 23 to 26, characterized in that: The base material of the shell is the same as the base material of the end cover.

42. The battery cell according to any one of claims 23 to 26, characterized in that: The battery cell is a cylindrical battery cell.

43. A battery cell, characterized in that: include: a housing having an opening; an electrode assembly housed in the housing, the electrode assembly having a first tab at one end facing the opening, the electrode assembly being a wound structure; an end cap, used to cover the opening to seal the electrode assembly in the housing; a current collecting member disposed between the end cover and the first electrode tab, the current collecting member comprising a first current collecting portion and a second current collecting portion, the first current collecting portion being used to abut against and weld with the end cover to form a first welding portion, and the second current collecting portion being used to abut against and weld with the first electrode tab to form a second welding portion; In which, the end cover includes a cover body and a first protrusion, the cover body is used to be welded with the first collecting part to form the first welding part, the first protrusion surrounds the outside of the cover body, and protrudes from the inner surface of the cover body in the direction facing the first pole ear, the first protrusion is used to abut against the first pole ear to support the first pole ear.

44. The battery cell according to claim 43, characterized in that A projection of the first welding portion along the thickness direction of the end cover and a projection of the second welding portion along the thickness direction of the end cover do not overlap.

45. The battery cell according to claim 44, characterized in that The electrode assembly is wound along a central axis to form a first electrode tab, wherein the first electrode tab includes N layer structures arranged around the central axis, and an extending direction of the central axis is parallel to a thickness direction of the end cap; The first tab is composed of a first annular portion and a second annular portion surrounding the first annular portion, the number of layer structures in the first annular portion is N1, the number of layer structures in the second annular portion is N2, N=N1+N2, the value of |N1-N2| is less than or equal to 2, and N1 and N2 are positive integers; The first annular portion is welded to the current collecting member to form a first portion, the second annular portion is welded to the current collecting member to form a second portion connected to the first portion, and the second welded portion is composed of the first portion and the second portion.

46. ​​The battery cell according to claim 45, characterized in that N3 continuous layer structures in the first annular portion arranged near the second annular portion are welded to the current collecting component to form the first part, and N4 continuous layer structures in the second annular portion arranged near the first annular portion are welded to the current collecting component to form the second part. The N3 continuous layer structures are continuously arranged with the N4 continuous layer structures, N4>N3≥1, and N3 and N4 are positive integers.

47. The battery cell according to claim 45 or 46, characterized in that: M continuous layer structures among all the layer structures are welded to the current collecting member to form the second welding portion, wherein 1 / 3≤M / N≤1 / 2, M≥2, and M is a positive integer.

48. The battery cell according to any one of claims 44 to 46, characterized in that: The second current collecting portion is protruding from the surface of the first current collecting portion facing the electrode assembly, and the second current collecting portion is provided with an avoidance recess on a side away from the electrode assembly, and the avoidance recess is used to avoid the second welding portion.

49. The battery cell according to claim 43, characterized in that A first recessed portion is formed on the end cover at a position corresponding to the first protrusion and is recessed from the outer surface of the cover body in a direction facing the electrode assembly. The bottom surface of the first recessed portion is closer to the first tab than the inner surface of the cover body.

50. The battery cell according to claim 43, wherein: The outer side surface of the first protrusion abuts against the inner surface of the shell and is used for welding with the shell to close the opening.

51. The battery cell according to claim 48, characterized in that The end cover further includes a second protrusion, the cover body surrounds the outer side of the second protrusion, and the second protrusion protrudes from the inner surface of the cover body in a direction facing the first tab and extends into the avoidance recess; A second recessed portion is formed on the end cover at a position corresponding to the second protrusion and is recessed from the outer surface of the cover body in a direction facing the electrode assembly.

52. The battery cell according to claim 51, characterized in that A weak portion is provided in an area of ​​the second convex portion opposite to the bottom surface of the second concave portion, wherein the weak portion is configured to rupture when the internal pressure of the battery cell reaches a threshold value to release the internal pressure; The avoidance recess is further used to separate the second collecting portion from the weak portion.

53. The battery cell according to any one of claims 43 to 46, characterized in that: The end cover is used to electrically connect the first tab and the housing.

54. The battery cell according to claim 53, characterized in that The housing further includes a side wall and a bottom wall connected to the side wall, wherein the side wall extends along the thickness direction of the end cover and is arranged around the outer periphery of the electrode assembly, and the bottom wall is provided with an electrode lead-out hole; The electrode assembly further includes a second electrode tab, wherein the first electrode tab and the second electrode tab have opposite polarities and are respectively located at two ends of the electrode assembly; The battery cell further includes an electrode terminal installed in the electrode lead-out hole, and the electrode terminal is electrically connected to the second electrode tab.

55. The battery cell according to claim 54, characterized in that The bottom wall and the side wall are integrally formed.

56. The battery cell according to claim 53, characterized in that The first electrode tab is a negative electrode tab, and the base material of the shell is steel.

57. The battery cell according to any one of claims 43 to 46, characterized in that: The base material of the shell is the same as the base material of the end cover.

58. The battery cell according to any one of claims 43 to 46, characterized in that: The battery cell is a cylindrical battery cell.

59. A battery, characterized in that The battery cell comprises a plurality of battery cells according to any one of claims 1 to 22, or a plurality of battery cells according to any one of claims 23 to 42, or a plurality of battery cells according to any one of claims 43 to 58.

60. An electrical device, characterized in that: A battery according to claim 59 is included for providing electrical energy.

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