Battery monomer, battery and electric device

Abstract

The invention provides a battery monomer, a battery and a power utilization device. The battery monomer comprises an electrode assembly, a shell assembly and a current collecting component, and the electrode assembly comprises a first tab; the shell assembly is used for accommodating the electrode assembly and comprises a first electrode leading-out part; the current collecting component comprises a first connecting part and a second connecting part which are connected, the first connecting part is conductively connected with the first tab, and the second connecting part is welded with the first electrode leading-out part; the melting point of the second connection portion is closer to the melting point of the first electrode lead-out portion than the melting point of the first connection portion.

Description

Battery cells, batteries and electrical devices Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry. Electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of the sustainable development of the automotive industry. For electric vehicles, battery technology is a key factor in their development.

[0003] In a battery, the current of the battery electrode is often conducted to the corresponding electrode lead-out part through a current collecting component. The current collecting component needs to be conductively connected to the electrode tab and the electrode lead-out part respectively. In related technologies, the materials of the electrode tab and the electrode lead-out part are different. When the current collecting component and the electrode lead-out part are welded, the welding performance difference between the different materials will affect the quality of the molten pool weld, thereby adversely affecting the reliability of the welding connection between the current collecting component and the electrode lead-out part.

[0004] Summary of the Invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present application is to provide a battery cell, a battery, and an electrical device to improve the reliability of the connection between the current collecting member and the electrode lead portion.

[0006] Embodiments of the first aspect of the present application provide a battery cell. The battery cell includes an electrode assembly, a housing assembly, and a current collecting member. The electrode assembly includes a first electrode tab; the housing assembly is used to accommodate the electrode assembly and includes a first electrode lead; the current collecting member includes a first connecting portion and a second connecting portion connected to each other, the first connecting portion being welded to the first electrode tab, and the second connecting portion being welded to the first electrode lead; wherein the material of the first connecting portion is different from the material of the second connecting portion, and the melting point T2 of the second connecting portion is closer to the melting point T3 of the first electrode lead than the melting point T1 of the first connecting portion.

[0007] In the technical solution of the embodiment of the present application, the current collecting component is provided with a first connecting part and a second connecting part connected to each other, the first connecting part is connected to the first pole ear, and the second connecting part is welded to the first electrode lead-out part, and the melting point T2 of the second connecting part is closer to the melting point T3 of the first electrode lead-out part than the melting point T1 of the first connecting part, so that the second connecting part and the first electrode lead-out part can be fused more smoothly when being welded, thereby alleviating the defect of poor quality of molten pool forming caused by differences in material welding performance, improving welding quality, and thereby improving the reliability of the connection between the current collecting component and the electrode lead-out part.

[0008] In some embodiments, the melting point T2 of the second connecting portion and the melting point T3 of the first electrode lead portion satisfy the following: 0.75×T3≤T2≤1.3×T3. Limiting the difference in the melting point of the second connecting portion to the melting point of the first electrode lead portion within a certain range allows for better fusion of the second connecting portion and the first electrode lead portion during welding, preventing miscibility or explosion points, reducing welding difficulty, and improving weld quality.

[0009] In some embodiments, the second connecting portion is made of at least one of chromium, nickel, and steel, and the first electrode lead portion is made of at least one of chromium, nickel, and steel. By selecting appropriate materials based on the welding target, the welding requirements of the current collecting member and the first electrode lead portion can be met, thereby improving the reliability of the weld connection.

[0010] In some embodiments, the material of the second connection portion is the same as that of the first electrode lead portion. Welding between the same materials is more reliable and can eliminate welding defects caused by differences in welding properties between different materials.

[0011] In some embodiments, the first connection portion includes a first metal layer and a first soldering layer, wherein the first soldering layer is disposed on a surface of the first metal layer. The soldering layer is beneficial for reducing welding defects, improving welding quality and reliability of welding connections.

[0012] In some embodiments, the first soldering layer is disposed on the surface of the first metal layer facing the first tab; and / or, the first connecting portion and the second connecting portion are welded together, and at least a portion of the first soldering layer is disposed on the surface of the first metal layer facing the second connecting portion. By disposing the soldering layer on the surface of the welding location, welding defects caused by material differences can be alleviated, thereby improving weld quality.

[0013] In some embodiments, the second connecting portion includes a second metal layer and a second soldering layer, and the second soldering layer is disposed on the surface of the second metal layer. The second soldering layer on the surface of the second metal layer facilitates welding connection between the second metal layer and other components, thereby improving weld quality.

[0014] In some embodiments, a second soldering layer is disposed on the surface of the second metal layer facing the first electrode lead-out portion; and / or, the first connecting portion and the second connecting portion are welded together, and at least a portion of the second soldering layer is disposed on the surface of the second metal layer facing the first connecting portion. By disposing a soldering layer on the surface of the welding location, welding defects caused by material differences can be mitigated, thereby improving weld quality.

[0015] In some embodiments, the housing assembly includes a shell and an end cap. The shell defines a housing space for accommodating the electrode assembly and an opening at one end of the housing space. The end cap is connected to the shell to cover the opening. The first electrode lead portion is the shell or the end cap. Separately providing the shell and end cap can better meet the requirements for accommodating the electrode assembly. Using the shell or end cap as the first electrode lead portion can simplify the battery structure.

[0016] In some embodiments, the second connecting portion is located between the first connecting portion and the end cap, the end cap includes an abutting portion that contacts the second connecting portion, and the second connecting portion is welded to the first connecting portion and the abutting portion, respectively. The contact and welding of the second connecting portion with the abutting portion of the end cap can reduce the required docking height of the second connecting portion along a first direction parallel to the axial direction of the electrode assembly, thereby reducing the space occupied by the housing assembly and facilitating an increase in the capacity density of the battery cells.

[0017] In some embodiments, the second connecting portion is welded to the abutting portion to form a first weld portion, and along a first direction parallel to the axial direction of the electrode assembly, the depth of the first weld portion is less than the sum of the thicknesses of the second connecting portion and the abutting portion. The depth of the first weld portion is less than the sum of the thicknesses of the second connecting portion and the abutting portion, so that the first weld portion can achieve a welded connection between the second connecting portion and the abutting portion without penetrating the second connecting portion and damaging the electrode assembly.

[0018] In some embodiments, the end cap includes a connected end cap body and a protrusion protruding from the end cap body toward the electrode assembly. The protrusion has a recess formed on a side facing away from the electrode assembly, and the abutment portion is located on the bottom wall of the protrusion. The abutment portion protrudes into the accommodation space to facilitate contact with the second connecting portion, thereby reducing the gap between the end cap and the second connecting portion and alleviating welding defects caused by the gap.

[0019] In some embodiments, the second connecting portion includes a vertical edge connected to the first connecting portion and extending in a first direction parallel to the axial direction of the electrode assembly. The outer side of the vertical edge is welded to the housing to form a first weld. Providing the vertical edge on the second connecting portion that abuts the inner side of the housing facilitates welding alignment of the second connecting portion and the housing, improves alignment accuracy, facilitates welding of the two by welding equipment, and improves weld quality.

[0020] In some embodiments, the first weld is formed by laser penetration from the outside of the housing and melting a portion of the vertical edge. Using external laser welding allows for greater space for laser welding equipment. Laser welding can be performed parallel to the housing surface, reducing the height of the first weld along the first axial direction of the electrode assembly. This reduces the height of the vertical edge against the housing, minimizing battery capacity loss.

[0021] In some embodiments, along a second direction perpendicular to the axial direction of the electrode assembly, the thickness d3 of the vertical side portion and the thickness d2 of the housing satisfy the following relationship: d3 / d2≥0.25. When the thickness d3 of the vertical side portion and the thickness d2 of the housing satisfy the following relationship: d3 / d2≥0.25, a reliable conductive connection between the current collecting member and the housing can be achieved while minimizing the impact on the connection between the current collecting member and the first tab.

[0022] In some embodiments, the thickness d2 of the housing satisfies the following conditions: 0.3 mm ≤ d2 ≤ 0.65 mm, and the thickness d3 of the vertical side satisfies the following conditions: 0.1 mm ≤ d3 ≤ 0.6 mm. Setting the thickness of the housing and the thickness of the vertical side within appropriate ranges can balance the strength requirements, energy density, and weld performance of the current collecting member and the housing, thereby improving the overall performance of the battery.

[0023] In some embodiments, along the second direction, the depth a of the first weld, the thickness d3 of the vertical side, and the thickness d2 of the shell satisfy the following relationship: a<d2+d3. By controlling the molten pool depth of the first weld to be less than the sum of the thickness of the vertical side and the shell thickness, the first weld can be prevented from penetrating the vertical side.

[0024] In some embodiments, the width b of the first weld along the first direction and the depth a of the first weld along the second direction satisfy the following relationship: b ≤ a; the second direction is perpendicular to the axial direction of the electrode assembly. By controlling the width b of the first weld along the second direction and the depth a of the first weld along the first direction to satisfy b ≤ a, the dimension of the first weld along the first direction can be minimized while improving the reliability of the connection between the current collecting member and the housing, thereby reducing the height of the vertical edge portion connecting to the housing and reducing battery capacity loss.

[0025] In some embodiments, along the first direction, the width c of the contact area between the vertical side and the housing and the width b of the first weld satisfy the following conditions: c ≥ b + 0.5 mm. When the width c of the contact area between the vertical side and the housing and the width b of the first weld satisfy c ≥ b + 0.5 mm, the dimensional and precision requirements for the welded connection are well met, and the resulting first weld achieves a reliable connection.

[0026] In some embodiments, the depth a of the first weld along the second direction, the width b of the first weld along the first direction, and the width c of the contact area between the second connection portion and the housing along the first direction satisfy the following conditions: 0.3 mm ≤ a ≤ 1 mm, 0.1 mm ≤ b ≤ 0.9 mm, and 0.8 mm ≤ c ≤ 4 mm, with the second direction being perpendicular to the axial direction of the electrode assembly. Reasonable selection of the depth a of the first weld along the first direction, the width b of the first weld along the second direction, and the width c of the contact area between the second connection portion and the housing along the second direction can facilitate a reliable connection of the first weld formed by welding the vertical edge portion to the housing while minimizing battery capacity loss.

[0027] In some embodiments, the first weld is formed by laser penetrating the vertical edge of the housing from the inside and melting a portion of the housing. Internal welding allows for direct detection of the docking position of the current collecting member and the housing, facilitating weld positioning and control, thereby improving weld quality.

[0028] In some embodiments, along the second direction, the thickness d3 of the vertical side and the thickness d2 of the casing satisfy the following relationship: 0.25 ≤ d3 / d2 ≤ 1. The second direction is perpendicular to the axial direction of the electrode assembly. Setting the thickness of the casing and vertical side to satisfy 0.25 ≤ d3 / d2 ≤ 1 can reduce the possibility of welding through the casing while achieving a reliable connection, thereby improving the overall performance of the battery.

[0029] In some embodiments, along the first direction, the width c of the contact area between the vertical side and the housing and the width b of the first weld satisfy the following conditions: c ≥ b + 0.5 mm. When the width c of the contact area between the vertical side and the housing and the width b of the first weld satisfy c ≥ b + 0.5 mm, the welding positioning accuracy requirements can be met, reducing battery capacity loss.

[0030] In some embodiments, the width b of the first weld along the first direction and the depth a of the first weld along the second direction satisfy the following relationship: b ≤ a; and the second direction is perpendicular to the axial direction of the electrode assembly. When the width b of the first weld along the second direction and the depth a of the first weld along the first direction satisfy b ≤ a, this facilitates the fusion connection between the vertical edges arranged along the second direction and the housing, and further reduces the space occupied in the height direction.

[0031] In some embodiments, along the second direction, the depth a of the first weld, the thickness d3 of the vertical edge, and the thickness d2 of the housing satisfy the following relationship: a<d2+d3. The depth a of the first weld, the thickness d3 of the vertical edge, and the thickness d2 of the housing satisfy the following relationship: a<d2+d3. This prevents the formed first weld from penetrating the housing during welding, effectively reducing the risk of electrolyte leakage from the battery cells.

[0032] In some embodiments, the thickness d2 of the housing satisfies the following conditions: 0.3 mm ≤ d2 ≤ 0.65 mm, and the thickness d3 of the vertical side satisfies the following conditions: 0.1 mm ≤ d3 ≤ 0.4 mm. Setting the thickness d2 of the housing to 0.3 mm ≤ d2 ≤ 0.65 mm and the thickness d3 of the vertical side to 0.1 mm ≤ d3 ≤ 0.4 mm can effectively balance the structural strength and corrosion resistance of the housing, the welding requirements between the housing and the current collecting member, and the energy density of the battery, thereby improving the overall performance of the battery.

[0033] In some embodiments, the depth a of the first weld along the second direction, the width b of the first weld along the first direction, and the width c of the contact area between the second connection portion and the housing along the first direction satisfy the following conditions: 0.3 mm ≤ a ≤ 1 mm, 0.3 mm ≤ b ≤ 1 mm, and 0.8 mm ≤ c ≤ 4 mm. Reasonable selection of the depth a of the first weld along the second direction, the width b of the first weld along the first direction, and the width c of the contact area between the second connection portion and the housing along the first direction can reduce the loss of battery energy density while meeting welding requirements.

[0034] In some embodiments, the first connection portion includes a transition connection portion and a tab connection portion, the tab connection portion being welded to the first tab, and the transition connection portion being welded to the second connection portion. The first connection portion is configured as a connected transition connection portion and tab connection portion, so as to be connected to the second connection portion and the first tab, respectively. This allows for independent welding operations to be performed without mutual interference, thereby ensuring the quality of the weld connection as much as possible and meeting the overcurrent requirements of the conductive connection.

[0035] In some embodiments, the transition connection portion is disposed along the outer edge of the tab connection portion and is welded to the inner side surface of the vertical side portion. Disposing the transition connection portion along the outer edge of the tab connection portion facilitates the connection between the transition connection portion and the vertical side portion, as well as the welding connection between the tab connection portion and the first tab, thereby avoiding mutual interference.

[0036] In some embodiments, the second connection portion further includes an overlap portion connected to the vertical side portion, and the overlap portion is welded to the transition connection portion. By providing the overlap portion for welding to the transition connection portion of the first connection portion, physical isolation from the first fusion portion can be achieved, thereby preventing laser light from leaking out during welding to form the first fusion portion and affecting the connection between the first connection portion and the first tab.

[0037] In some embodiments, the overlapping portion includes a first side surface proximal to the electrode assembly and a second side surface distal to the electrode assembly, and the transition portion is welded to the first side surface. The transition portion is welded to the first side surface, and the first connection portion is located on a side of the second connection portion closer to the electrode assembly, which is equivalent to the first connection portion protruding toward the side where the electrode assembly is located, so that the first connection portion is closely attached to the first tab, thereby facilitating the connection between the first connection portion and the first tab.

[0038] In some embodiments, the overlap portion is provided with a hollow portion corresponding to the tab connection portion, and the hollow portion is configured to allow laser light to pass through to achieve a welded connection between the tab connection portion and the first tab. By providing the hollow portion corresponding to the tab connection portion in the overlap portion, the overlap portion can be prevented from affecting the welding of the tab connection portion and the first tab, thereby reducing unnecessary laser energy loss and improving welding efficiency and quality.

[0039] In some embodiments, the hollow portion includes a plurality of hollow slots spaced apart from each other, the hollow slots corresponding to the weld seams between the tab connection portion and the first tab. Providing hollow slots corresponding to the weld seams between the tab connection portion and the first tab not only reduces unnecessary energy loss, but the shape of the hollow slots also allows for positioning of the weld seams, thereby improving welding efficiency.

[0040] In some embodiments, the overlapping portion is provided with a hollow portion corresponding to the tab connection portion. The overlapping portion includes a first side surface proximal to the electrode assembly, a second side surface distal to the electrode assembly, and an end surface located between the first and second side surfaces and defining the hollow portion. The transition portion is welded to the end surface. The welded connection of the transition portion to the end surface allows the current collecting component to occupy less space within the housing, thereby ensuring the energy density of the battery.

[0041] In some embodiments, the transition connection portion and the tab connection portion are coplanar flat plates. This coplanar flat plate shape can reduce the amount of processing required on the first connection portion. Furthermore, the flat plate shape of the first connection portion can minimize its size along the first direction, thereby reducing the impact on the battery's energy density.

[0042] In some embodiments, the overlapping portion includes a first side surface proximal to the electrode assembly and a second side surface distal to the electrode assembly, and the transition portion is welded to the second side surface. In this embodiment, the transition portion is welded to the second side surface, which can reduce the overall height of the current collecting member along the first direction, thereby occupying the accommodation space within the height region, making the internal structure of the battery housing more compact and reducing the loss of energy density of the battery.

[0043] In some embodiments, the overlap portion is provided with a hollow portion corresponding to the tab connection portion, and the side of the tab connection portion closest to the electrode assembly at least partially passes through the hollow portion to connect with the first tab. The tab connection portion at least partially penetrates the hollow region and connects with the first tab, which helps to reduce the welding gap between the two, reduces the occurrence of cold welds, and improves the reliability of the weld connection, thereby meeting the connection requirements and the requirements of conductive overcurrent.

[0044] In some embodiments, the electrode assembly includes a second electrode tab having a different polarity from the first electrode tab, the first electrode tab and the second electrode tab are respectively located at both ends of the electrode assembly, the shell assembly includes a shell and an end cover, the shell forms a receiving space for accommodating the electrode assembly, the shell includes an end wall located at one end of the receiving space, and an opening located at the other end of the receiving space; the end cover is connected to the shell to cover the opening; the first electrode lead-out portion is the end cover or the shell; the shell assembly also includes a second electrode lead-out portion, the second electrode lead-out portion is passed through the end wall, and is electrically connected to the second electrode tab.

[0045] An embodiment of the second aspect of the present application provides a battery, comprising the battery cell in the above embodiment.

[0046] An embodiment of the third aspect of the present application provides an electrical device, which includes the battery in the above embodiment, and the battery is used to provide electrical energy.

[0047] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0049] FIG1 is a schematic structural diagram of a vehicle according to some embodiments of the present application;

[0050] FIG2 is a schematic diagram of the exploded structure of a battery according to some embodiments of the present application;

[0051] FIG3 is a schematic diagram of the exploded structure of a battery cell according to some embodiments of the present application;

[0052] FIG4 is a cross-sectional view of a battery cell according to some embodiments of the present application;

[0053] FIG5 is a schematic diagram of the exploded structure of a current collecting component according to some embodiments of the present application;

[0054] FIG6 is a cross-sectional view of a battery cell according to some other embodiments of the present application;

[0055] FIG7 is a cross-sectional view of a battery cell according to some other embodiments of the present application;

[0056] FIG8 is a cross-sectional view and a top view in the direction of A of a current collecting component according to some embodiments of the present application;

[0057] FIG9 is a cross-sectional view and a top view in the direction of A of a current collecting member according to other embodiments of the present application;

[0058] FIG10 is a cross-sectional view and a top view in the direction of A of a current collecting member according to some other embodiments of the present application;

[0059] FIG11 is a cross-sectional view and a top view in the direction of A of a current collecting component according to some other embodiments of the present application;

[0060] FIG12 is a cross-sectional view and a top view in the direction of A of a current collecting member according to some other embodiments of the present application;

[0061] Reference numerals:

[0062] Vehicles 1000;

[0063] Battery 100, controller 200, motor 300;

[0064] Box body 10, first part 11, second part 12;

[0065] Battery cell 20, electrode assembly 21, first electrode tab 211, second electrode tab 212;

[0066] Housing assembly 22, first electrode lead portion 22A, second electrode lead portion 22B, housing 221, side wall 2211, end wall 2212, end cover 222, abutting portion 2221, end cover body 2222, and protrusion 2223;

[0067] Current collecting member 23, first connecting portion 231, first metal layer 231A, first soldering layer 231B, transition connecting portion 2311, tab connecting portion 2312, second connecting portion 232, first metal layer 232A, first soldering layer 232B, vertical edge 2321, overlapping portion 2322, first side surface 2322a, second side surface 2322b, hollow portion 2322c, end surface 2322d;

[0068] First weld portion 24 . DETAILED DESCRIPTION

[0069] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0070] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments 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 figure descriptions are intended to cover non-exclusive inclusions.

[0071] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0072] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present 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. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0073] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, "a and / or B" can represent three situations: the existence of "a" alone, the existence of "a" and "b" together, and the existence of "b" alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0074] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0075] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.

[0076] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0077] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0078] The applicant has noted that the negative electrode tab of the battery's electrode assembly and the electrode lead-out structure (e.g., the shell) are usually electrically connected via a current collecting component. The current collecting component is responsible for collecting current from the tab to the shell. Since the current collecting component primarily considers conductivity, its material is usually copper or nickel-plated copper. In addition to conductivity, the shell focuses more on strength and corrosion resistance, and its material is usually aluminum alloy, stainless steel, etc. Therefore, the melting points of the materials of the current collecting component and the shell are quite different. During welding, the steel shell and the copper current collecting component are infinitely soluble in each other at high temperatures. Since the linear expansion coefficient of copper is about 40% greater than that of steel, the weld formed by the two will generate large stresses during the cooling process due to the shrinkage of the molten pool, which is prone to cracking, affecting the reliability of the conductive connection between the tab and the shell.

[0079] In order to improve the reliability of the connection between the current collecting component and the electrode lead-out portion, the applicant has discovered that the current collecting component can be arranged into a first connecting portion and a second connecting portion that are connected to the electrode tab and the electrode lead-out portion, respectively, and the two connecting portions can be made of different materials, such as materials with different melting points, so that when the two connecting portions are welded to the electrode tab and the electrode lead-out portion, respectively, a more reliable connection weld can be formed, thereby realizing a reliable current path between the electrode assembly and the electrode lead-out portion.

[0080] In addition, the applicant also found that, based on the improvement of the materials of the first connecting part and the second connecting part of the current collecting component, further optimizing the first welding part formed by the second connecting part and the electrode lead-out part and the structural form of the current collecting component can improve the quality of the weld to achieve reliable connection, while also optimizing the structural layout and size design within the battery cell, improving the space utilization within the battery cell, and reducing the capacity loss of the battery.

[0081] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power supply system comprising the battery cells and batteries disclosed in this application can be used to improve the stability of battery performance.

[0082] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0083] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0084] Please refer to Figure 1, which is a schematic structural diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0085] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0086] Please refer to Figure 2, which is an exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a storage space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for the battery cell 20. The second portion 12 can be a hollow structure with one end open. The first portion 11 can be a plate-like structure, with the first portion 11 overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 together define a storage space. Alternatively, the first portion 11 and the second portion 12 can each be a hollow structure with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0087] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0088] Each battery cell 20 may be a secondary battery or a primary battery, and may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0089] Please refer to Figures 3 to 5. Figure 3 is an exploded schematic diagram of a battery cell 20 provided in some embodiments of the present application. Figure 4 is a cross-sectional view of a battery cell 20 provided in some embodiments of the present application. Figure 5 is an exploded structural schematic diagram of a current collecting component 23 in some embodiments of the present application.

[0090] A battery cell 20 is the smallest unit that makes up a battery. As shown in Figure 3, a battery cell 20 includes an electrode assembly 21, a housing assembly 22, and a current collecting member 23. The electrode assembly 21 includes a first electrode tab 211. The housing assembly 22 is used to house the electrode assembly 21 and includes a first electrode lead 22A. The current collecting member 23 includes a first connecting portion 231 and a second connecting portion 232. The first connecting portion 231 is electrically connected to the first electrode tab 211, while the second connecting portion 232 is welded to the first electrode lead 22A of the housing assembly 22. The material of the first connecting portion 231 is different from that of the second connecting portion 232. The melting point T2 of the second connecting portion 232 is closer to the melting point T3 of the first electrode lead 22A than the melting point T1 of the first connecting portion 231.

[0091] The electrode assembly 21 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 21 may be contained in the outer shell assembly 22. The electrode assembly 21 is mainly formed by winding or stacking the positive electrode sheet and the negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet with active substances constitute the main body of the battery cell assembly, and the parts of the positive electrode sheet and the negative electrode sheet without active substances each constitute the tab. The positive electrode tab and the negative electrode tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive electrode active substance and the negative electrode active substance react with the electrolyte, and the tabs are connected to the corresponding electrode lead-out parts to form a current loop.

[0092] The first electrode tab 211 is connected to the first electrode lead portion 22A via the current collecting member 23. In one example, the first electrode tab 211 can be a positive electrode tab, and the first electrode lead portion 22A is a positive electrode lead. In another example, the first electrode tab 211 can be a negative electrode tab, and the first electrode lead portion 22A is a negative electrode lead.

[0093] The housing assembly 22 is a component used to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 21, electrolyte, and other components. The housing assembly 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing assembly 22 can be determined according to the specific shape and size of the electrode assembly 21. The housing assembly 22 can be made of various materials, such as iron, aluminum, stainless steel, aluminum alloy, etc. The housing assembly 22 includes a shell 221 and an end cap 222. The first electrode lead 22A can be a conductive component, such as a pole, that is inserted through the shell 221 or the end cap 222. In some embodiments, the first electrode lead 22A can also be the shell 221 or the end cap 222, that is, the first electrode tab 211 is conductively connected to the shell 221 or the end cap 222 through the current collecting member 23, so that the shell 221 or the end cap 222 serves as the first electrode lead 22A of the first electrode tab 211. The first electrode lead portion 22A may be a metal layer made of a single material, a metal layer made of multiple different materials, or a stack of multiple materials with different functions.

[0094] The current collecting member 23 is made of a conductive material and includes a first connecting portion 231 and a second connecting portion 232 connected to each other. The material of the first connecting portion 231 is different from that of the second connecting portion 232, meaning that they have different melting points. The first connecting portion 231 is electrically connected to the first electrode tab 211 and can be fixedly connected by welding, such as laser welding, ultrasonic welding, or resistance welding. The material of the second connecting portion 232 is different from that of the first connecting portion 231 and is fixedly connected to the first electrode lead 22A of the housing assembly 22 by welding, such as laser welding, ultrasonic welding, or resistance welding. The current collecting member 23 is connected to the first electrode tab 211 and the housing assembly 22 via the first connecting portion 231 and the second connecting portion 232, respectively. This collects the current generated by the electrode assembly 21 and connects it to the other electrode lead to form a current loop.

[0095] According to an embodiment of the present application, the current collecting component 23 is set to a first connecting portion 231 and a second connecting portion 232 connected to each other, the first connecting portion 231 is conductively connected to the first pole ear 211, and the second connecting portion 232 is welded to the first electrode lead-out portion 22A of the shell assembly 22. The melting point T2 of the second connecting portion 232 is closer to the melting point T3 of the first electrode lead-out portion 22A than the melting point T1 of the first connecting portion 231, so that the second connecting portion 232 and the first electrode lead-out portion 22A can be fused more smoothly when welding, thereby alleviating the defect of poor molten pool forming quality caused by differences in material welding performance and improving welding quality.

[0096] In some embodiments, the melting point T2 of the second connection portion 232 and the melting point T3 of the first electrode lead portion 22A satisfy the following relationship: 0.75×T3≤T2≤1.3×T3.

[0097] Limiting the ratio of the melting point of the material of the second connecting part 232 to the melting point of the first electrode lead-out part 22A of the outer shell component 22 to be within a certain range can alleviate poor welding caused by a large difference in the melting points of the two, so that the second connecting part 232 and the first electrode lead-out part 22A can be better fused when welding, and problems of incompatibility or explosion points will not occur during welding, thereby reducing the difficulty of welding and improving the quality of the weld.

[0098] In some embodiments, the material of the second connection portion 232 is at least one of chromium, nickel, and steel, and the material of the first electrode lead portion 22A is at least one of chromium, nickel, and steel.

[0099] In order to ensure smooth fusion between the second connecting portion 232 and the first electrode lead-out portion 22A, the material of the second connecting portion 232 is at least one of chromium, nickel and steel, and the material of the first electrode lead-out portion 22A is at least one of chromium, nickel and steel. This can improve the welding quality between the current collecting component 23 and the shell assembly 22 and improve the reliability of the welding connection.

[0100] In some embodiments, the material of the second connection portion 232 is the same as the material of the first electrode lead portion 22A.

[0101] Since the welding properties of the same materials are consistent, various welding defects caused by differences in welding properties will not occur, thereby improving the welding reliability between the current collecting member 23 and the first electrode lead-out portion 22A of the housing assembly 22.

[0102] In some embodiments, referring to FIG. 5 , the first connection portion 231 of the current collecting member 23 includes a first metal layer 231A and a first soldering layer 231B. The first soldering layer 231B is disposed on a surface of the first metal layer 231A.

[0103] The first soldering layer 231B and the first metal layer 231A are stacked along the thickness of the first connecting portion 231. The soldering layer aids in welding and improves the quality of the weld. The first soldering layer 231B can be electroplated on the surface of the first metal layer 231A. The soldering layer can be applied to the entire surface of the first metal layer 231A, or, depending on the specific welding location and material, to facilitate welding, the soldering layer can be applied only to the surface of the welding location.

[0104] The soldering layer is helpful in reducing welding defects. Providing the first soldering layer 231B on the surface of the first metal layer 231A can improve welding quality and reliability of welding connections.

[0105] In some embodiments, the first soldering layer 231B is disposed on the surface of the first metal layer 231A facing the first tab 211; and / or, the first connecting portion 231 and the second connecting portion 232 are welded together, and at least a portion of the first soldering layer 231B is disposed on the surface of the first metal layer 231A facing the second connecting portion 232.

[0106] In addition to being welded to the first tab 211, the first metal layer 231A can also be welded to the second connection portion 232. Considering that different materials have varying welding properties, such as melting points, laser absorptivity, and linear expansion coefficients, a first soldering layer 231B can be disposed on the surface of the first metal layer 231A at locations where welding is required, based on the materials and welding requirements of the first metal layer 231A and the object being welded.

[0107] By providing a soldering layer on the surface of the area where the welding position is located, welding defects caused by differences in material welding properties can be alleviated, and the quality of the weld between the first connecting portion 231 and the first tab 211 and / or the second connecting portion 232 can be improved.

[0108] In some embodiments, the second connection portion 232 of the current collecting member 23 includes a second metal layer 232A and a second solder paste layer 232B, and the second solder paste layer 232B is disposed on a surface of the second metal layer 232A.

[0109] A reliable conductive connection is formed between the second connecting portion 232 and the housing assembly 22 by welding. A fixed conductive connection can also be achieved between the second connecting portion 232 and the first connecting portion 231 by welding. A second soldering layer 232B is disposed on the surface of the second metal layer 232A, such that the second soldering layer 232B and the second metal layer 232A are two portions stacked along the thickness direction of the second connecting portion 232. In one example, the second soldering layer 232B can be a nickel-plated layer formed by electroplating.

[0110] The second soldering layer 232B is provided on the surface of the second metal layer 232A to facilitate the welding connection between the second metal layer 232A and other components, thereby improving the quality of the weld.

[0111] In some embodiments, the second soldering layer 232B is disposed on the surface of the second metal layer 232A facing the first electrode lead-out portion 22A; and / or, the first connection portion 231 and the second connection portion 232 are welded together, and at least a portion of the second soldering layer 232B is disposed on the surface of the second metal layer 232A facing the first connection portion 231.

[0112] The second metal layer 232A can be welded to the first electrode lead portion 22A of the housing assembly 22, or can be welded to the first connection portion 231. The second soldering layer 232B can be provided on a surface on one side of the second metal layer 232A welded to the first electrode lead portion 22A, and / or, the second soldering layer 232B can be provided on a surface on one side of the second metal layer 232A welded to the first connection portion 231. In one example, surfaces on opposite sides of the second metal layer 232A are welded to the first connection portion 231 and the first electrode lead portion 22A, respectively, and the second soldering layer 232B is correspondingly provided on surfaces on both sides of the second metal layer 232A for welding to the first connection portion 231 and the first electrode lead portion 22A, respectively.

[0113] By providing a soldering layer on the surface of the area where the welding position is located, welding defects caused by differences in material welding properties can be alleviated, and the weld quality between the second connection portion 232 and the housing assembly 22 and / or the first connection 231 can be improved.

[0114] In some embodiments, the housing assembly 22 includes a housing 221 and an end cap 222. The housing 221 defines a housing space for accommodating the electrode assembly 21 and an opening at one end of the housing space. The end cap 222 is connected to the housing 221 to cover the opening. The first electrode lead 22A may be either the housing 221 or the end cap 222.

[0115] The housing 221 may include a sidewall 2211 and an end wall 2212 located at one end of the sidewall 2211. The sidewall 2211 and the end wall 2212 may be integrally stamped or welded together. The sidewall 2211 and the end wall 2212 together form a housing space for accommodating the electrode assembly 21. One end of the housing space is the end wall 2212, and the other end opposite the end wall 2212 is an opening.

[0116] The end cap 222 is a component that covers the opening of the housing 221 to isolate the internal environment of the battery cell 20 from the external environment. The housing 221 and the end cap 222 can be separate components. An opening can be provided in the housing 221, and the end cap 222 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 222 and the housing 221 can be integrated. Specifically, the end cap 222 and the housing 221 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 221 needs to be encapsulated, the end cap 222 is placed over the housing 221. Alternatively, the shape of the end cap 222 can be adapted to match the shape of the housing 221 to fit the housing 221. Optionally, the end cap 222 can be made of a material with a certain hardness and strength (such as an aluminum alloy). This prevents the end cap 222 from deforming when subjected to compression or collision, thereby providing the battery cell 20 with greater structural strength and improved safety.

[0117] By separately providing the shell 221 and the end cover 222 , the accommodation requirements of the electrode assembly 21 can be better met. The shell 221 or the end cover 222 serving as the first electrode lead-out portion 22A can simplify the structure of the battery.

[0118] In some embodiments, as shown in Figure 4, the second connection portion 232 is located between the first connection portion 231 and the end cover 222, the end cover 222 includes an abutment portion 2221, the abutment portion 2221 contacts the second connection portion 232, and the second connection portion 232 is welded to the first connection portion 231 and the abutment portion 2221 respectively.

[0119] The abutment portion 2221 is a portion of the end cap 222 used to connect to the second connection portion 232. For example, the end cap 222 is in the shape of a flat plate, and the abutment portion 2221 can be a partial area of ​​the flat plate that contacts the second connection portion. The second connection portion 232 is located between the first connection portion 231 and the end cap 222, so that the two side surfaces of the second connection portion 232 are welded to the first connection portion 231 and the end cap 222, respectively. In one example, the second connection portion 232 is in the shape of a flat plate, and a side surface of the second connection portion 232 close to the electrode assembly 21 is welded to the first connection portion 231, and a side surface of the second connection portion 232 away from the electrode assembly 21 is welded to the end cap 222. The end cap 222 includes an abutment portion 2221, and the abutment portion 2221 is used to contact the second connection portion 232 so that the two can achieve a conductive connection after welding. After the end cap 222 covers the opening, the second connecting portion 232 is located within the accommodation space. A laser can be used to penetrate the abutting portion 2221 from the outside and melt the portion of the second connecting portion 232 in contact with the abutting portion 2221, thereby forming a molten weld between the contact surfaces of the abutting portion 2221 and the second connecting portion 232. In this embodiment, the end cap 222 serves as the first electrode lead portion 22A.

[0120] The second connection portion 232, by being welded to the abutment portion 2221, can collect the current from the electrode assembly 21 and conduct it to the end cap 222. The end cap 222 and the housing 221 are also electrically connected, allowing the housing 221 to serve as the second electrode lead portion of the electrode assembly. Welding the second connection portion 232 to the end cap 222 reduces the required height of the second connection portion 232 along a first direction X parallel to the axial direction of the electrode assembly, thereby reducing the space occupied by the housing assembly 22 and facilitating an increase in the capacity density of the battery cell 20.

[0121] In some embodiments, as shown in Figure 4, the second connecting portion 232 is welded to the abutting portion 2221 to form a first welding portion 24. Along the first direction X parallel to the axial direction of the electrode assembly, the depth a of the first welding portion 24 is less than the sum of the thickness d1 of the second connecting portion 232 and the thickness d0 of the abutting portion 2221, that is, a<d0+d1.

[0122] The abutting portion 2221 is the portion that contacts the second connecting portion 232 for weld connection. The thickness d0 of the abutting portion 2221 is the thickness of the portion welded to the second connecting portion 232 along the first direction X. The thickness d1 of the second connecting portion 232 is the thickness of the portion welded to the abutting portion 2221 along the first direction X. The depth a of the first welded portion 24 is the maximum penetration depth of the first welded portion 24 along the first direction.

[0123] The depth a of the first welding portion 24 is smaller than the sum of the thickness d1 of the second connection portion 232 and the thickness d0 of the abutting portion 2221 , so that the first welding portion 24 can realize the welding connection between the second connection portion 232 and the abutting portion 2221 without penetrating the second connection portion 232 and damaging the electrode assembly 21 .

[0124] In some embodiments, as shown in Figure 4, the end cover 222 includes a connected end cover body 2222 and a protrusion 2223 protruding from the end cover body 2222 toward the electrode assembly 21. A recess (not shown in the figure) is formed on the side of the protrusion 2223 facing away from the electrode assembly 21, and the abutment portion 2221 is located on the bottom wall of the protrusion 2223.

[0125] The end cap 222 is generally plate-shaped, and the end cap body 2222 and the protrusion 2223 are different parts of the end cap 222 divided perpendicular to the thickness direction. The side of the protrusion 2223 close to the electrode assembly 21 protrudes toward the electrode assembly 21, and the side away from the electrode assembly 21 is concave in the direction of the electrode assembly 21 to form a recess. The protrusion 2223 includes a bottom wall away from the end cap body 2222, and a connecting wall connecting the bottom wall and the end cap body 2222. The abutment 2221 is located on the bottom wall of the protrusion 2223. Specifically, the abutment 2221 can be a part of the bottom wall of the protrusion 2223 or the entire bottom wall.

[0126] The abutment portion 2221 is located on the bottom wall of the convex portion 2223, so that the abutment portion 2221 can protrude into the accommodating space, thereby being more conducive to contact with the second connecting portion 232, reducing the gap between the end cover 222 and the second connecting portion 232 and alleviating poor welding caused by the gap.

[0127] Please refer to Figure 6, which is a cross-sectional view of a battery cell 20 provided in other embodiments of the present application. In some embodiments, the second connection portion 232 of the current collecting member 23 includes a vertical side portion 2321 connected to the first connection portion 231 and extending in a first direction X parallel to the axial direction of the electrode assembly. The outer side surface of the vertical side portion 2321 is welded to the housing 221 to form a first weld portion 24.

[0128] The first direction X is parallel to the axial direction of the electrode assembly 21, and the second direction Y is perpendicular to the axial direction of the electrode assembly 21. The vertical side 2321 extends along the first direction X, and the shape of the vertical side 2321 is the same as that of the housing 221, which can be cylindrical, rectangular, or the like. The outer side surface of the vertical side 2321 of the second connecting portion 232 is aligned with the inner surface of the housing 221 to achieve docking and positioning of the current collecting member 23 and the housing 221, so that welding equipment can weld them together to form the first weld 24. In this embodiment, the housing 221 serves as the first electrode lead portion 22A.

[0129] By providing a vertical side portion 2321 on the second connection portion 232 that is connected to the inner side surface of the shell 221, it is beneficial to the welding alignment of the second connection portion 232 and the shell 221, improving the alignment accuracy, so that the welding equipment can weld the two, which is beneficial to improving the welding quality.

[0130] In some embodiments, the first welding portion 24 is configured to be formed by laser penetrating the housing 221 from the outside of the housing 221 and melting a portion of the vertical edge portion 2321 .

[0131] In this embodiment, laser welding is used. Laser welding involves irradiating a high-intensity laser beam onto a metal surface. The interaction between the laser and the metal causes the metal to melt and form a weld. Laser welding features highly concentrated energy density, extremely rapid heating and cooling, a minimal heat-affected zone, and high efficiency.

[0132] The first weld 24 between the shell 221 and the second connecting portion 232 can be formed by external welding, that is, a laser generator is located outside the battery cell and emits a laser beam toward the surface of the shell 221. The energy of the laser penetrates the shell 221 and melts part of the vertical edge 2321. The specific welding process is as follows: first, the shell 221 and the vertical edge 2321, the two parts to be welded, are installed and positioned together, and then a laser beam is directed toward the surface of the shell 221 at the corresponding position on the vertical edge 2321. The laser beam penetrates the shell 221 and is then absorbed by the material of the vertical edge 2321. The laser energy causes the penetrated portion of the shell 221 and the corresponding vertical edge 2321 to melt on the side of the shell 221, and then welded together to form the first weld 24.

[0133] In one example, the laser is directed toward the housing 221 and the vertical edge 2321 in a direction perpendicular to the surface of the housing 221 to form the first weld 24. The width of the first weld 24 is the maximum dimension of the first weld 24 along the first direction X.

[0134] The external welding method allows the laser welding equipment to have a larger layout space. The laser can perform welding in a direction parallel to the surface of the shell, which can reduce the height of the first welding portion 24 along the first direction X parallel to the axial direction of the electrode assembly 21, thereby reducing the docking height between the vertical side portion 2321 and the shell 221 and reducing the capacity loss of the battery.

[0135] In some embodiments, along the second direction Y, the thickness d3 of the vertical side portion 2321 and the thickness d2 of the housing 221 satisfy: d3 / d2≥0.25.

[0136] The vertical side portion 2321 is connected to the first connection portion 231. In order to prevent the laser from penetrating the vertical side portion 2321 when the vertical side portion 2321 is welded to the shell 221, thereby affecting the first connection portion 231 next to it, the vertical side portion 2321 needs to meet a certain thickness. When the thickness d3 of the vertical side portion 2321 and the thickness d2 of the shell meet d3 / d2≥0.25, a reliable conductive connection between the current collecting component 23 and the shell 221 can be achieved while avoiding affecting the connection between the current collecting component 23 and the first pole tab 211 as much as possible. Exemplarily, the thickness d3 of the vertical side portion 2321 and the thickness d2 of the shell 221 can also meet: d3 / d2≥0.5, thereby further preventing the laser from passing through the second connection portion 232 and affecting the connection between the first connection portion 231 and the first pole tab 211, or even damaging the electrode assembly 21.

[0137] In some embodiments, the thickness d2 of the shell 221 satisfies: 0.3 mm ≤ d2 ≤ 0.65 mm, and the thickness d3 of the vertical side portion 2321 satisfies: 0.1 mm ≤ d3 ≤ 0.6 mm.

[0138] The battery case houses various components and electrolyte. The case 221 needs to have a certain thickness to meet both strength and corrosion resistance requirements. However, the thickness of the case 221 should not be too large, as this will affect the battery's energy density. Therefore, the thickness d2 of the case 221 is set to 0.3mm≤d2≤0.65mm, achieving a balance between the battery's strength requirements and energy density. The vertical edges 2321 require a certain thickness for welding to the case 221. However, the thickness of the vertical edges 2321 should not be too large, as this will affect the battery's energy density. Therefore, the thickness d3 of the vertical edges is set to 0.1mm≤d3≤0.6mm, achieving a balance between the welding performance of the current collecting member 23 and the case 221 and the battery's energy density.

[0139] In some embodiments, along the second direction Y, the depth a of the first welding portion 24 , the thickness d3 of the vertical side portion 2321 , and the thickness d2 of the shell 221 satisfy: a<d2+d3.

[0140] The depth a of the first welding portion 24 is smaller than the sum of the thickness d3 of the vertical side 2321 and the thickness d2 of the shell 221 , so that the first welding portion 24 does not penetrate the vertical side 2321 , thereby preventing the laser from adversely affecting other components inside the shell.

[0141] In some embodiments, along the first direction X, the width of the first weld portion 24 is b, along the second direction Y, the depth of the first weld portion 24 is a, and a and b satisfy: b≤a.

[0142] The shell 221 is located on the outside of the vertical side 2321. The first fusion joint 24 formed by external laser welding is a deep penetration weld, which limits the width of the first fusion joint 24 to be smaller than the depth. The size of the first fusion joint 24 along the first direction X can be reduced as much as possible on the basis of improving the connection reliability between the current collecting component 23 and the shell 221, thereby reducing the docking height between the vertical side 2321 and the shell 221 and reducing the capacity loss of the battery.

[0143] In some embodiments, along the first direction X, the width c of the contact area between the vertical side portion 2321 and the housing 221 and the width b of the first welding portion 24 satisfy: c≥b+0.5 mm.

[0144] Due to the limited machining accuracy of components and the errors caused by positioning accuracy, it is difficult to ensure that the laser welding will proceed completely along the preset welding trajectory during welding. In order to prevent the formation of the first weld 24 from being affected by dimensional errors, docking positioning errors, and welding accuracy control errors, it is necessary to set the width c of the contact area between the vertical edge 2321 and the shell 221 to be larger than the width b of the first weld 24, thereby providing a certain offset margin during laser welding. This can reduce the accuracy requirements for dimensional, positioning, and laser welding trajectory control. Even if the laser deflects to a certain extent, the first weld 24 can still be well formed to achieve a reliable connection.

[0145] After research, it was found that when the width c of the fitting area between the vertical side 2321 and the shell 221 and the width b of the first weld 24 satisfy c ≥ b + 0.5 mm, the dimensional and precision requirements of the welded connection can be well met, and the formed first weld 24 can achieve a reliable connection. In another example, the width c of the fitting area between the vertical side 2321 and the shell 221 and the width b of the first weld 24 can also satisfy c ≥ b + 1 mm, so that the fitting area between the vertical side 2321 and the shell 221 is sufficiently large, thereby providing a greater margin for deviation, reducing cold and leaky welds caused by deviation, and improving the molding quality and connection reliability of the first weld 24.

[0146] In some embodiments, the depth a of the first welding portion 24 along the second direction Y, the width b of the first welding portion 24 along the first direction X, and the width c of the fitting area between the vertical side portion 2321 and the shell 221 along the first direction X satisfy: 0.3mm≤a≤1mm, 0.1mm≤b≤0.9mm, 0.8mm≤c≤4mm.

[0147] Through multiple experiments on welding the current collecting component and the shell, and taking into account more factors such as laser power, welding speed, welding materials and size, the depth a of the first welding portion 24 along the second direction Y is set to 0.3mm≤a≤1mm, the width b of the first welding portion 24 along the first direction X is set to 0.1mm≤b≤0.9mm, and the width c of the fitting area between the vertical side 2321 and the shell 221 along the first direction X is set to 0.8mm≤c≤4mm. This can better facilitate the reliable connection of the first welding portion formed by welding the vertical side 2321 to the shell 221, while taking into account the capacity loss of the battery.

[0148] 7 is a cross-sectional view of a battery cell according to some other embodiments of the present application. Referring to FIG7 , in some embodiments, the first weld portion 24 is formed by laser penetrating the vertical edge portion 2321 from the inner side of the shell 221 and melting a portion of the shell 221 .

[0149] In this embodiment, the first weld 24 is formed by laser internal welding. During internal welding, the laser is typically directed at the current collecting member 23 and the housing 221 at an angle (non-perpendicular). The laser energy raises the temperature of the housing 221 material, melting the vertical edge 2321 and a portion of the housing 221, thereby welding the vertical edge 2321 and a portion of the housing 221 together to form a butt weld or a through weld.

[0150] When laser internal welding is used to weld the current collecting component and the shell, due to the limited space inside the shell, the laser needs to be tilted to enter the welding position, and the battery cell or laser needs to be rotated during welding to form butt welding or penetration welding along the circumference. Since copper has a low laser absorption rate, a large power is required to produce a molten pool by welding, while steel has a high laser absorption rate and a much smaller power is required to produce a molten pool by welding. Under the set welding power, only one of butt welding or penetration welding can be satisfied. When the laser welding position is offset from the docking position of the current collecting component and the shell, a cold weld will occur, thereby affecting the reliability of the connection. Therefore, when the current collecting component and the shell are docked, a vertical edge docking of sufficient height is required. Although this can meet the influence of positioning accuracy fluctuations on welding, it occupies too much internal space of the battery, affecting the energy density of the battery.

[0151] In this embodiment, the melting point of the second connecting part is close to the melting point of the shell. During welding, penetrating welding can be performed using a set power, which is beneficial to the formation of the molten pool weld. Even if the laser is offset, it will not affect the forming quality of the weld. At the same time, it can also reduce the requirements for the vertical edge docking height.

[0152] In some embodiments, the thickness d3 of the vertical side portion 2321 along the second direction Y and the thickness d2 of the housing 221 satisfy the following relationship: 0.25≤d3 / d2≤1.

[0153] In order to improve the forming quality of the first welding portion 24 when the vertical side portion 2321 and the shell 221 are welded from the inside of the shell 221, the thickness of the shell 221 and the vertical side portion 2321 is set to satisfy 0.25≤d3 / d2≤1. This can reduce the possibility of the shell 221 being welded through while achieving a reliable connection, thereby improving the overall performance of the battery.

[0154] In one example, the thickness d3 of the vertical side 2321 and the thickness d2 of the shell 221 may also satisfy: 0.25≤d3 / d2≤0.75, so as to further reduce the possibility of a cold weld between the vertical side 2321 and the shell 221 and improve the reliability of the welding connection.

[0155] In some embodiments, the width c of the contact area between the vertical side portion 2321 and the housing 221 along the first direction X and the width b of the first welding portion satisfy: c≥b+0.5 mm.

[0156] Due to the limited machining accuracy of components and the errors caused by positioning accuracy, it is difficult to ensure that the laser welding will proceed completely along the preset welding trajectory during welding. In order to prevent the formation of the first weld 24 from being affected by dimensional errors, docking positioning errors, and welding accuracy control errors, it is necessary to set the width c of the contact area between the vertical edge 2321 and the shell 221 to be larger than the width b of the first weld 24, thereby providing a certain offset margin during laser welding. This can reduce the accuracy requirements for dimensional, positioning, and laser welding trajectory control. Even if the laser deflects to a certain extent, the first weld 24 can still be well formed to achieve a reliable connection.

[0157] In one example, the width c of the fitting area between the vertical edge 2321 and the shell 221 and the width b of the first welding portion 24 may also satisfy c≥b+1 mm, so as to allow a larger welding error during welding and improve welding efficiency.

[0158] In some embodiments, the width b of the first welding portion 24 along the first direction X and the depth a of the first welding portion 24 along the second direction Y satisfy: b≤a.

[0159] When the width b of the first welding portion 24 along the first direction X and the depth a of the first welding portion 24 along the second direction Y satisfy b≤a, the first welding portion 24 presents a narrow and deep molten weld. This type of weld is conducive to reducing the maximum dimension of the width b of the first welding portion 24 along the first direction, thereby reducing the docking height between the second connecting portion 232 and the shell 221 along the first direction X, and on this basis reducing the space occupied in the accommodating space.

[0160] In some embodiments, along the second direction Y perpendicular to the axis of the electrode assembly, the depth a of the first weld portion 24 , the thickness d3 of the vertical side portion 2321 , and the thickness d2 of the shell 221 satisfy: a<d2+d3.

[0161] The depth a of the first weld 24 , the thickness d3 of the vertical side 2321 , and the thickness d2 of the shell 221 are set to satisfy a<d2+d3, which can prevent the formed first weld 24 from penetrating the shell 221 during welding, effectively reducing the risk of electrolyte leakage of the battery cell 20.

[0162] In some embodiments, the thickness d2 of the shell 221 satisfies: 0.3 mm ≤ d2 ≤ 0.65 mm, and the thickness d3 of the vertical side portion 2321 satisfies: 0.1 mm ≤ d3 ≤ 0.4 mm.

[0163] The battery housing houses the electrode assembly and electrolyte. The housing 221 needs to be thick enough to ensure both strength and corrosion resistance. However, the thickness of the housing 221 should be limited, as this will affect the battery's energy density. The vertical edge 2321 of the second connecting portion 232 needs to be thick enough to weld to the housing 221. Excessive thickness can also affect welding efficiency and weld quality.

[0164] In this embodiment, the thickness d2 of the shell 221 is set to 0.3mm≤d2≤0.65mm, and the thickness d3 of the vertical side 2321 is set to 0.1mm≤d3≤0.4mm. This can well take into account the structural strength and corrosion resistance of the shell, the welding requirements between the shell and the current collecting component, and the energy density of the battery, thereby improving the overall performance of the battery.

[0165] In some embodiments, the depth a of the first welding portion 24 along the second direction Y, the width b of the first welding portion 24 along the first direction X, and the width c of the bonding area between the second connection portion 232 and the shell 221 along the first direction X satisfy: 0.3mm≤a≤1mm, 0.3mm≤b≤1mm, 0.8mm≤c≤4mm.

[0166] The dimensional parameters of the first welding portion 24 and the width of the fitting area have an important influence on the reliability of the welding connection and the energy density of the battery. Reasonable selection of the depth a of the first welding portion 24 along the second direction Y, the width b of the first welding portion 24 along the first direction X, and the width c of the fitting area between the second connection portion 232 and the shell 221 along the first direction X can reduce the loss of battery energy density while meeting the welding requirements.

[0167] Please refer to Figures 8 to 12, which are cross-sectional views and top views taken along line A of the current collecting member 23 of some embodiments of the present application. In some embodiments, the first connection portion 231 of the current collecting member 23 includes a transition connection portion 2311 and a tab connection portion 2312 connected to each other. The tab connection portion 2312 is welded to the first tab 211, and the transition connection portion 2311 is welded to the second connection portion 232.

[0168] The transition portion 2311 and the second connection portion 232 can have various structural forms. They can be separate, independent components connected by welding, riveting, threading, or other methods. Alternatively, they can be directly integrally formed, with both being part of the integral first connection portion 231. The transition portion 2311 can be coplanar with the second connection portion 232, or they can be on different planes.

[0169] The transition portion 2311 and the second connection portion 232 can be welded together using laser welding, ultrasonic welding, friction welding, or resistance welding. In one example, as shown in FIG6 , the transition portion 2311 can be directly welded to the inner side surface of the vertical side portion 2321 of the second connection portion 232. In another example, the transition portion 2311 can be welded to other components or other portions of the second connection portion 232, thereby achieving an indirect connection to the vertical side portion 2321.

[0170] The first connection part 231 is set to be connected to the transition connection part 2311 and the tab connection part 2312, so as to be connected to the second connection part 232 and the first tab 211 respectively, so that welding operations can be carried out independently to avoid mutual influence, so as to ensure the quality of the welding connection as much as possible and meet the overcurrent requirements of the conductive connection.

[0171] 8 , in some embodiments, the transition connection portion 2311 is provided along the outer edge of the tab connection portion 2312 and is welded to the inner side surface of the vertical side portion 2321 .

[0172] The vertical side portion 2321 needs to be fitted and docked with the inner side surface of the shell 221, and the first pole ear 211 is located at the end close to the opening in the accommodating cavity formed by the shell 221. The transition connection portion 2311 is arranged along the outer edge of the pole ear connection portion 2312, which is more conducive to the connection between the transition connection portion 2311 and the vertical side portion 2321, as well as the welding connection between the pole ear connection portion 2312 and the first pole ear 211, to avoid mutual influence.

[0173] 9 to 12 , in some embodiments, the second connection portion 232 further includes a lap portion 2322 connected to the vertical side portion 2321 , and the lap portion 2322 is welded to the transition connection portion 2311 .

[0174] The overlapping portion 2322 can extend in a different direction from the vertical side portion 2321, that is, the two are not coplanar. For example, the overlapping portion 2322 can be a flat plate parallel to the second direction Y. The overlapping portion 2322 and the vertical side portion 2321 can be independently prepared components connected by various methods such as welding, riveting, and threading. They can also be directly integrally formed, or formed from a single component through mechanical processing methods such as stamping and cutting. For example, a folded edge structure formed by stamping one end of the vertical side portion 2321 serves as the overlapping portion 2322. The overlapping portion 2322 is welded to the transition connecting portion 2311 to achieve a conductive connection between the first connecting portion 231 and the second connecting portion 232.

[0175] By providing the overlap portion 2322 for welding connection with the transition connection portion 2311 of the first connection portion, physical isolation from the first fusion portion 24 can be achieved, thereby preventing laser leakage from affecting the connection between the first connection portion 231 and the first tab 211 when the first fusion portion 24 is formed by welding.

[0176] 9 , in some embodiments, the overlapping portion 2322 includes a first side surface 2322 a close to the electrode assembly 21 and a second side surface 2322 b away from the electrode assembly 21 , and the transition portion 2311 is welded to the first side surface 2322 a of the overlapping portion 2322 .

[0177] The overlapping portion 2322 has a first side surface 2322a and a second side surface 2322b opposite to each other, wherein the first side surface 2322a and the second side surface 2322b can be planes parallel to the second direction Y, or can be inclined surfaces or curved surfaces intersecting the second direction Y. The weld connection between the transition connection portion 2311 and the first side surface 2322a means that the first connection portion 231 is connected to the side of the second connection portion 232 close to the electrode assembly 21.

[0178] The transition connection portion 2311 is welded to the first side surface 2322a, and the first connection portion 231 is located on the side of the second connection portion 232 that is closer to the electrode assembly 21, which is equivalent to the first connection portion 231 protruding toward the side where the electrode assembly 21 is located, so that the first connection portion 231 is closely attached to the first pole ear 211, which is conducive to the connection between the first connection portion 231 and the first pole ear 211.

[0179] 9 , in some embodiments, the overlapping portion 2322 is provided with a hollow portion 2322 c corresponding to the tab connecting portion 2312 , and the hollow portion 2322 c is configured to allow laser to pass through to achieve a welding connection between the tab connecting portion 2312 and the first tab 211 .

[0180] Because the first connection portion 231 is located on the side of the overlapping portion 2322 close to the electrode assembly 21, when welding the first connection portion 231 to the first electrode tab 211, the laser needs to pass through the location of the second connection portion 232 to reach the welding position between the first connection portion 231 and the first electrode tab 211. In one example, the overlapping portion 2322 can be a flat plate parallel to the second direction Y. Based on this, a hollow area corresponding to the electrode tab connection portion 2312 is provided in the overlapping portion 2322 to allow the laser to pass through, thereby achieving a welded connection between the electrode tab connection portion 2312 and the first electrode tab 211. This can prevent the overlapping portion 2322 from affecting the welding between the electrode tab connection portion 2312 and the first electrode tab 211, reduce unnecessary laser energy loss, and help improve welding efficiency and welding quality.

[0181] 10 , in some embodiments, the hollow portion 2322 c includes a plurality of hollow grooves (not shown) spaced apart, and the positions of the welds between the hollow grooves and the tab connecting portion 2312 and the first tab 211 correspond to each other.

[0182] The hollow portion 2322c may include a plurality of hollow grooves arranged at intervals, and the plurality of hollow grooves may respectively correspond to the welding positions between the tab connection portion 2312 and the first tab 211, so that the laser passes through the overlap portion 232 to weld the tab connection portion 2312 and the first tab 211. In one example, the weld between the tab connection portion 2312 and the first tab 211 is a plurality of straight welds evenly spaced circumferentially around the axis of the electrode assembly 21 and extending radially. The hollow portion 2322c may be a pattern consisting of a plurality of hollow grooves adapted to the shape of the weld between the tab connection portion 2312 and the first tab 211, so as to achieve a welded connection between the tab connection portion 2312 and the first tab 211.

[0183] By providing a hollow groove corresponding to the weld between the tab connecting portion 2312 and the first tab 211 , not only can unnecessary energy loss be reduced, but the shape of the hollow groove can also provide positioning for the weld position, thereby improving welding efficiency.

[0184] 11 , in some embodiments, the overlapping portion 2322 is provided with a hollow portion 2322c corresponding to the tab connection portion 2312, the overlapping portion 2322 includes a first side surface 2322a close to the electrode assembly 21 and a second side surface 2322b away from the electrode assembly 21, and an end surface 2322d located between the first side surface 2322a and the second side surface 2322b and defining the hollow portion 2322c, and the transition connection portion 2311 is welded to the end surface 2322d.

[0185] The transition portion 2311 and the end surface 2322d can be connected by butt welding. For example, the upper side of the transition portion 2311 can be coplanar with the second side 2322b of the overlapping portion 2322, or the lower side of the transition portion 2311 can be coplanar with the first side 2322a of the overlapping portion 2322, or both the upper and lower sides of the transition portion 2311 can be coplanar with both the second side 2322b and the first side 2322a of the overlapping portion 2322. The shape of the hollow area 2322c matches that of the first connecting portion 231. In one example, the hollow area 2322c is circular, and the outer edge of the first connecting portion 231 is also circular.

[0186] In some embodiments, the weld formed by welding the transition connection portion 2311 and the overlap portion 2322 can be a continuous, closed weld, or a multi-section weld set at intervals, or a plurality of weld points set at intervals, as long as the connection and flow requirements are met.

[0187] The transition portion 2311 is welded to the end surface 2322d. This separates the weld between the first and second connection portions 231 and 232 from the vertical edge 2321, preventing interference between the welds and mitigating welding deformation. The weld between the transition portion 2311 and the end surface 2322d allows the current collecting member 23 to occupy less space within the housing, thereby ensuring the battery's energy density.

[0188] 11 , in some embodiments, the transition connection portion 2311 and the tab connection portion 2312 are coplanar flat plates.

[0189] The transition connection part 2311 and the tab connection part 2312 are coplanar flat plates, which can reduce the amount of processing on the first connection part. For example, they can be made by one-time molding, reducing manufacturing costs. At the same time, the flat-plate-shaped first connection part can occupy less internal space of the shell, reducing the impact on the energy density of the battery.

[0190] It is understood that the transition connection portion 2311 and the tab connection portion 2312 may be two adjacent regions of the flat first connection portion 231. For example, the transition connection portion 2311 is a region close to the periphery, and the tab connection portion 2312 is a region close to the center.

[0191] 12 , in some embodiments, the overlapping portion 2322 includes a first side surface 2322a close to the electrode assembly 21 and a second side surface 2322b away from the electrode assembly, and the transition connection portion 2311 is welded to the second side surface 2322b.

[0192] For example, the transition portion 2311 of the first connection portion 231 and the overlap portion of the second connection portion 232 can be made into two parts with matching shapes so as to be welded together after splicing. In one example, the laser penetrates the transition portion 2311 and partially melts the overlap portion 2322 to form a through weld.

[0193] In this embodiment, the transition connection portion 2311 is welded to the second side surface 2322b, so that the first connection portion 231 and the second connection portion 232 have a larger overlapping area along the height direction of the shell. This can reduce the overall height of the current collecting component 23 along the first direction X, thereby occupying the accommodation space within the height area, making the internal structure of the battery shell more compact and reducing the loss of energy density of the battery.

[0194] 12 , in some embodiments, the overlapping portion 2322 is provided with a hollow portion 2322 c corresponding to the tab connection portion 2312 , and a side of the tab connection portion 2312 close to the electrode assembly 21 at least partially passes through the hollow portion 2322 c to connect with the first tab 211 .

[0195] As shown in Figure 11, the overlapping portion 2322 can be a circular ring with a hollow central area. The side of the pole ear connecting portion 2312 close to the electrode assembly 21 protrudes toward the direction of the electrode assembly 21. The protrusion passes through the hollow portion 2322c formed by the overlapping portion 2322 and is welded to the first pole ear 211.

[0196] In one example, the tab connection portion 2312 may also be partially raised toward the side where the electrode assembly 21 is located. In this case, the raised portion contacts and welds with the first tab 211 to form a weld. In order to reduce the possibility of a cold weld occurring in the weld connection between the tab connection portion 2312 and the first tab 211, the raised surface of the tab connection portion 2312 may be set to a side surface of the protruding overlap portion 2322 close to the electrode assembly 21. This allows the tab connection portion 2312 to contact the first tab 211, or even press the tab connection portion 2312 against the first tab 211, thereby improving the reliability of the weld connection.

[0197] The tab connection portion 2312 at least partially penetrates the hollow area and is connected to the first tab 211, which is beneficial to reducing the welding gap between the two, reducing the occurrence of cold solder joints, and improving the reliability of the welding connection, thereby meeting the connection requirements and conductive overcurrent requirements.

[0198] In some embodiments, as shown in FIG. 4 and FIG. 5 , the electrode assembly 21 further includes a second electrode tab 212 having a different polarity from the first electrode tab 211 ; the first electrode tab 211 and the second electrode tab 212 are respectively located at two ends of the electrode assembly 21 .

[0199] The housing assembly 22 includes a shell 221 and an end cap 222. The shell 221 forms a storage space for accommodating the electrode assembly 21. The shell 221 includes an end wall 2212 at one end of the storage space and an opening at the other end of the storage space. The end cap 222 is connected to the shell 221 to cover the opening of the storage space. The first electrode lead portion 22A is either the shell 221 or the end cap 222.

[0200] The housing assembly 22 further includes a second electrode lead portion 22B. The second electrode lead portion 22B passes through the end wall 2212 and is electrically connected to the second electrode tab 212 .

[0201] The second electrode lead-out portion 22B can be a pole, and a mounting hole is provided on the end wall 2212. The second electrode lead-out portion 22B is insulated and connected to the mounting hole on the end wall 2212 by an insulating member. The part of the second electrode lead-out portion 22B located in the accommodating space is electrically connected to the second pole ear 212, so that the current of the second pole ear 212 can be conducted to the outside of the shell assembly 22 through the second electrode lead-out portion 22B.

[0202] An embodiment of the second aspect of the present application provides a battery 100 , which includes the battery cell 20 in the above embodiment.

[0203] An embodiment of the third aspect of the present application provides an electrical device, which includes the battery in the above embodiment, and the battery is used to provide electrical energy.

[0204] The structure of the battery cell 20 of the present application is described below by taking a cylindrical battery cell 20 as an example through a specific embodiment.

[0205] The battery cell 20 includes an electrode assembly 21, a housing assembly 22, and a current collecting member 23. The electrode assembly 21 includes a first electrode tab 211 and a second electrode tab 212 of different polarities. The housing assembly 22 includes a shell 221 and an end cap 222. The shell 221 forms a housing for accommodating the electrode assembly 21. The shell 221 includes an end wall 2212 at one end of the housing and an opening at the other end of the housing. The end cap 222 is connected to the shell 221 to cover the opening of the housing.

[0206] The housing assembly 22 further includes a first electrode lead portion 22A and a second electrode lead portion 22B. The first electrode lead portion 22A may be a shell 221 or an end cover 222 . The second electrode lead portion 22B is disposed through the end wall 2212 and is electrically connected to the second electrode tab 212 .

[0207] The current collecting component 23 includes a first connecting portion 231 and a second connecting portion 232 connected to each other. The first connecting portion 231 is conductively connected to the first pole tab 211, and the second connecting portion 232 is welded to the shell 221; the first pole tab 211 and the current collecting component 23 are located at one end of the shell 221 close to the opening, and the second pole tab 212 is located at an end of the shell 221 away from the opening and is electrically connected to the second electrode lead-out portion 22B. The second electrode lead-out portion 22B passes through the end wall 2212 of the shell 221 away from the opening and is insulated from the shell 221.

[0208] The first electrode tab 211 is made of copper, nickel, or copper-plated nickel. The first connecting portion 231 and the second connecting portion 232 are made of different materials. Specifically, the melting point T1 of the first connecting portion 231, the melting point T2 of the second connecting portion 232, and the melting point T3 of the first electrode lead portion 22A satisfy the following relationship: |T3-T1|>|T3-T2|. For example, the first connecting portion 231 is made of copper, the second connecting portion 232 is made of at least one of chromium, nickel, and steel, and the first electrode lead portion 22A is made of at least one of chromium, nickel, and steel.

[0209] The second connecting portion 232 includes a vertical edge 2321. The vertical edge 2321 can be welded to the housing 221 by external or internal welding to form a first welded portion 24. Along the second direction Y, the depth a of the first welded portion 24, the thickness d3 of the vertical edge 2321, and the thickness d2 of the housing 221 satisfy the following relationship: a < d2 + d3. Along the first direction X, the width of the first welded portion 24 is b, and along the second direction Y, the depth of the first welded portion 24 is a. Furthermore, a and b satisfy the following relationship: b ≤ a.

[0210] The width c of the contact area between the vertical side 2321 and the housing 221 and the width b of the first weld 24 satisfy c ≥ b + 0.5 mm. The thickness d2 of the housing 221 satisfies: 0.3 mm ≤ d2 ≤ 0.65 mm, and the thickness d3 of the vertical side 2321 satisfies: 0.1 mm ≤ d3 ≤ 0.4 mm. During external welding, the depth a of the first weld 24 along the second direction Y satisfies: 0.3 mm ≤ a ≤ 1 mm, the width b of the first weld 24 along the first direction X satisfies: 0.1 mm ≤ b ≤ 0.9 mm, and the width c of the contact area between the vertical side 2321 and the housing 221 along the first direction X satisfies: 0.8 mm ≤ c ≤ 4 mm. During internal welding, the depth a of the first welding portion 24 along the second direction Y, the width b of the first welding portion 24 along the first direction X, and the width c of the bonding area between the second connection portion 232 and the shell 221 along the first direction X satisfy: 0.3mm≤a≤1mm, 0.3mm≤b≤1mm, 0.8mm≤c≤4mm.

[0211] The second connection portion 232 also includes a lap portion 2322 on a different surface from the vertical side portion 2321. The first connection portion 231 includes a transition connection portion 2311 and a pole ear connection portion 2312. The lap portion 2322 includes a first side surface 2322a close to the electrode assembly 21 and a second side surface 2322b away from the electrode assembly 21, and an end surface 2322d located between the first side surface 2322a and the second side surface 2322b and defining a hollow area 2322c. The transition connection portion 2311 can be welded to any one of the first side surface 2322a, the second side surface 2322b or the end surface 2322d of the lap portion 2322, and the pole ear connection portion 2312 is welded to the first pole ear 211, thereby realizing conductive connection from the first pole ear 211 to the shell 221.

[0212] 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 or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, comprising: An electrode assembly including a first electrode tab; A housing assembly, used to accommodate the electrode assembly, the housing assembly comprising a first electrode lead-out portion; A current collecting member, comprising a first connecting portion and a second connecting portion connected to each other, wherein the first connecting portion is welded to the first electrode tab, and the second connecting portion is welded to the first electrode lead-out portion; The material of the first connection portion is different from the material of the second connection portion, and the melting point T2 of the second connection portion is closer to the melting point T3 of the first electrode lead portion than the melting point T1 of the first connection portion.

2. The battery cell according to claim 1, wherein: The melting point T2 of the second connection portion and the melting point T3 of the first electrode lead portion satisfy: 0.75×T3≤T2≤1.3×T3.

3. The battery cell according to claim 1 or 2, wherein: The material of the second connection portion is at least one of chromium, nickel and steel, and the material of the first electrode lead-out portion is at least one of chromium, nickel and steel.

4. The battery cell according to any one of claims 1 to 3, wherein: The material of the second connection portion is the same as that of the first electrode lead portion.

5. The battery cell according to any one of claims 1 to 4, wherein: The first connection portion includes a first metal layer and a first soldering layer, and the first soldering layer is arranged on the surface of the first metal layer.

6. The battery cell according to claim 5, wherein: The first soldering layer is disposed on a surface of the first metal layer facing the first electrode tab; and / or the first connecting portion and the second connecting portion are welded and connected, and at least a portion of the first soldering layer is disposed on a surface of the first metal layer facing the second connecting portion.

7. The battery cell according to any one of claims 1 to 6, wherein: The second connection portion includes a second metal layer and a second soldering layer, and the second soldering layer is disposed on the surface of the second metal layer.

8. The battery cell according to claim 7, wherein: The second soldering layer is disposed on a surface of the second metal layer facing the housing assembly; and / or the first connection portion and the second connection portion are welded and connected, and at least a portion of the second soldering layer is disposed on a surface of the second metal layer facing the first connection portion.

9. The battery cell according to any one of claims 1 to 8, wherein: The housing assembly comprises: A housing, forming a receiving space for receiving the electrode assembly, and an opening at one end of the receiving space; an end cover connected to the housing to cover the opening; The first electrode lead-out portion is the shell or the end cover.

10. The battery cell according to claim 9, wherein: The second connection portion is located between the first connection portion and the end cover, the end cover includes an abutment portion, the abutment portion is in contact with the second connection portion, and the second connection portion is respectively welded to the first connection portion and the abutment portion.

11. The battery cell according to claim 10, wherein: The second connection portion is welded to the abutment portion to form a first welding portion. Along a first direction parallel to the axial direction of the electrode assembly, a depth a of the first welding portion is less than the sum of a thickness d1 of the second connection portion and a thickness d0 of the abutment portion.

12. The battery cell according to claim 11, wherein: The end cap comprises a connected end cap body and a convex portion protruding from the end cap body toward the electrode assembly, a concave portion is formed on a side of the convex portion away from the electrode assembly, and the abutting portion is located on a bottom wall of the convex portion.

13. The battery cell according to claim 9, wherein: The second connection portion includes a vertical side portion connected to the first connection portion and extending along a first direction, and an outer side surface of the vertical side portion is welded to the shell to form a first welding portion; The first direction is parallel to the axial direction of the electrode assembly.

14. The battery cell according to claim 13, wherein: The first welded portion is configured to be formed by laser penetrating the housing from the outside of the housing and melting a portion of the vertical side.

15. The battery cell according to claim 14, wherein: The thickness d3 of the vertical side portion and the thickness d2 of the shell satisfy: d3 / d2≥0.

25.

16. The battery cell according to claim 15, wherein: The thickness d2 of the shell satisfies: 0.3mm≤d2≤0.65mm, and the thickness d3 of the vertical side satisfies: 0.1mm≤d3≤0.6mm.

17. The battery cell according to any one of claims 14 to 16, wherein: Along a second direction perpendicular to the axial direction of the electrode assembly, the depth a of the first weld portion, the thickness d3 of the vertical side portion, and the thickness d2 of the shell satisfy: a <d2+d3。 18. The battery cell according to any one of claims 14 to 17, wherein: Along a second direction perpendicular to the axial direction of the electrode assembly, a width b of the first welding portion along the first direction and a depth a of the first welding portion along the second direction satisfy: b≤a.

19. The battery cell according to any one of claims 14 to 18, wherein: Along the first direction, a width c of a fitting area between the vertical edge and the shell and a width b of the first welding portion satisfy: c≥b+0.5 mm.

20. The battery cell according to any one of claims 14 to 19, wherein: The depth a of the first welding portion along the second direction, the width b of the first welding portion along the first direction, and the width c of the bonding area between the second connecting portion and the housing along the first direction satisfy: 0.3 mm ≤ a ≤ 1 mm, 0.1 mm ≤ b ≤ 0.9 mm, and 0.8 mm ≤ c ≤ 4 mm; The second direction is perpendicular to the axial direction of the electrode assembly.

21. The battery cell according to claim 13, wherein: The first welded portion is configured to be formed by laser penetrating the vertical side portion from the inner side of the shell and melting a portion of the shell.

22. The battery cell according to claim 21, wherein: Along the second direction, the thickness d3 of the vertical side portion and the thickness d2 of the shell satisfy: 0.25≤d3 / d2≤1; The second direction is perpendicular to the axial direction of the electrode assembly.

23. The battery cell according to claim 21 or 22, wherein: Along the first direction, a width c of a fitting area between the vertical edge and the shell and a width b of the first welding portion satisfy: c≥b+0.5 mm.

24. The battery cell according to any one of claims 21 to 23, wherein: The width b of the first welding portion along the first direction and the depth a of the first welding portion along the second direction satisfy: b≤a; The second direction is perpendicular to the axial direction of the electrode assembly.

25. The battery cell according to claim 24, wherein: Along the second direction, the depth a of the first welded portion, d3 of the vertical edge portion, and the thickness d2 of the shell satisfy: a <d2+d3。 26. The battery cell according to any one of claims 21 to 25, wherein: The thickness d2 of the shell satisfies: 0.3mm≤d2≤0.65mm, and the thickness d3 of the vertical side satisfies: 0.1mm≤d3≤0.4mm.

27. The battery cell according to any one of claims 21 to 26, wherein: The depth a of the first welding portion along the second direction, the width b of the first welding portion along the first direction, and the width c of the bonding area between the second connection portion and the shell along the first direction satisfy: 0.3mm≤a≤1mm, 0.3mm≤b≤1mm, 0.8mm≤c≤4mm.

28. The battery cell according to any one of claims 13 to 27, wherein: The first connection portion includes a transition connection portion and a pole tab connection portion which are connected to each other. The pole tab connection portion is welded to the first pole tab, and the transition connection portion is welded to the second connection portion.

29. The battery cell according to claim 28, wherein: The transition connection portion is arranged along the outer edge of the tab connection portion and is connected to the inner side surface of the vertical side portion.

30. The battery cell according to claim 28, wherein: The second connection portion further includes an overlap portion connected to the vertical side portion, and the overlap portion is welded to the transition connection portion.

31. The battery cell according to claim 30, wherein: The overlapping portion includes a first side surface close to the electrode assembly and a second side surface away from the electrode assembly, and the transition connection portion is welded to the first side surface.

32. The battery cell according to claim 31, wherein: The overlapping portion is provided with a hollow portion corresponding to the pole tab connecting portion, and the hollow portion is configured to allow laser to pass through to achieve welding connection between the pole tab connecting portion and the first pole tab.

33. The battery cell according to claim 32, wherein: The hollow portion includes a plurality of hollow grooves arranged at intervals, and the hollow grooves correspond to the welding seams between the pole tab connecting portion and the first pole tab.

34. The battery cell according to claim 30, wherein: The overlapping portion is provided with a hollow portion corresponding to the pole ear connecting portion, the overlapping portion includes a first side surface close to the electrode assembly and a second side surface away from the electrode assembly, and an end surface located between the first side surface and the second side surface and defining the hollow portion, and the transition connecting portion is welded to the end surface.

35. The battery cell according to any one of claims 28 to 34, wherein: The transition connection portion and the tab connection portion are in the shape of coplanar flat plates.

36. The battery cell according to claim 30, wherein: The overlapping portion includes a first side surface close to the electrode assembly and a second side surface away from the electrode assembly, and the transition connection portion is welded to the second side surface.

37. The battery cell according to claim 36, wherein: The overlapping portion is provided with a hollow portion corresponding to the pole tab connecting portion, and a side of the pole tab connecting portion close to the electrode assembly at least partially passes through the hollow portion to be connected to the first pole tab.

38. The battery cell according to any one of claims 1 to 37, wherein: The electrode assembly includes a second electrode tab having a different polarity from the first electrode tab, and the first electrode tab and the second electrode tab are respectively located at two ends of the electrode assembly. The housing assembly comprises a shell and an end cap, the shell forms a storage space for accommodating the electrode assembly, the shell comprises an end wall located at one end of the storage space, and an opening located at the other end of the storage space; the end cap is connected to the shell to cover the opening; the first electrode lead-out portion is the end cap or the shell; The housing assembly further includes a second electrode lead-out portion, which is disposed through the end wall and is electrically connected to the second electrode tab.

39. A battery comprising the battery cell according to any one of claims 1 to 38.

40. An electrical device, comprising the battery as claimed in claim 39, wherein the battery is used for providing electrical energy.

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