Battery monomer, battery device and electric equipment

Abstract

The invention discloses a battery monomer, a battery device and electric equipment. The battery cell includes a housing and an electrode assembly. The electrode assembly is accommodated in the shell and comprises a main body part and a plurality of first tabs led out from the main body part, the plurality of first tabs are stacked, the plurality of first tabs are welded to form a first welding part, the first welding part comprises at least one first part and at least one second part, the thickness of the first part is smaller than that of the second part, and the thickness of the second part is smaller than that of the first part. In the thickness direction of the first welding part, the sum of the projected areas of all the first parts is larger than the sum of the projected areas of all the second parts. The area of the plurality of first tabs, which is highly compacted, occupies a larger area, so that the interlayer gap of the plurality of first tabs on the whole first welding part can be reduced, the welding strength and stability among the plurality of first tabs can be improved, the cracking risk of the first tabs in the welding process can be reduced, and the welding quality of the first tabs can be improved. And the over-current capability of the first tab and the reliability of the battery monomer can be improved.

Description

Technical Field

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

[0002] With the development of new energy technologies, batteries are being used more and more widely. For example, batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles and electric cars, as well as in military equipment and aerospace and many other fields.

[0003] The development of battery technology must take into account multiple design factors, such as energy density, cycle life, assembly efficiency, and processing technology, as well as battery reliability. Summary of the Invention

[0004] This application provides a battery cell, a battery device, and an electrical appliance that can improve reliability.

[0005] According to a first aspect of this application, a battery cell is provided, the battery cell including a housing and an electrode assembly. The electrode assembly is housed within the housing and includes a main body portion and a plurality of first tabs extending from the main body portion. The plurality of first tabs are stacked and welded together to form a first weld portion. The first weld portion includes at least one first portion and at least one second portion. The thickness of the first portion is less than the thickness of the second portion. Along the thickness direction of the first weld portion, the sum of the projected areas of all the first portions is greater than the sum of the projected areas of all the second portions.

[0006] The degree to which the multiple first tabs are compacted in the first part is greater than the degree to which they are compacted in the second part. The area occupied by the multiple first tabs with a greater degree of compaction is larger, which can reduce the interlayer gap between the multiple first tabs in the first weld, improve the welding strength and stability between the multiple first tabs, and also reduce the risk of cracking of the first tabs during the welding process, which is beneficial to improving the current carrying capacity of the first tabs and the reliability of the battery cells.

[0007] In some embodiments, in a first portion, there is a gap between at least partially adjacent first tabs; in a second portion, there is a gap between at least partially adjacent first tabs; the average gap between the plurality of first tabs in the first portion is smaller than the average gap between the plurality of first tabs in the second portion. This reduces the risk of first tab breakage and failure, and also reduces the welding power required during the welding process of the plurality of first tabs, thereby improving welding efficiency.

[0008] In some embodiments, in the first part, the average gap between the plurality of first tabs is d1; in the second part, the average gap between the plurality of first tabs is d2; 100≥d2 / d1≥5. This is beneficial for reducing the overall interlayer gap of the first weld portion, improving the welding effect and welding strength, and also reducing the risk of the first tabs breaking during the welding process.

[0009] In some embodiments, 20 ≥ d2 / d1 ≥ 10. This allows for a better balance between the overall interlayer gap of the first weld and the structural stability of the first electrode tab.

[0010] In some embodiments, in the first part, the average gap between the plurality of first tabs is d1, 3μm≥d1>0, which can improve the welding effect and welding strength between the plurality of first tabs; and / or, in the second part, the average gap between the plurality of first tabs is d2, 5μm≥d2>0, which can reduce the thickness difference between the first part and the second part, and help reduce the risk of breakage at the connection between the first part and the second part.

[0011] In some embodiments, 0.2μm≥d1≥0.01μm can balance the welding effect of multiple first tabs and the structural stability of the first tabs; and / or, 1μm≥d2≥0.1μm can simultaneously reduce the risk of breakage at the connection between the first part and the second part, as well as the risk of tearing of the first tab.

[0012] In some embodiments, along the thickness direction, the sum of the projected areas of all the first portions is S1, and the sum of the projected areas of all the second portions is S2, where 50 ≥ S1 / S2 > 1. Therefore, the area of ​​the second portions can be appropriately increased, which helps to reduce the risk of the first electrode tab being torn when the first welded part detaches from the welding device.

[0013] In some embodiments, 25 ≥ S1 / S2 ≥ 10. This allows for a balance between the welding strength of the first welded portion and the structural stability of the first electrode tab.

[0014] In some embodiments, there are multiple second portions, and the projection of each second portion along the thickness direction is elongated. These multiple second portions are intersected and form a grid structure. The more uniform distribution of the second and first portions helps reduce adhesion between the first weld and the welding device, further reducing the risk of tearing of the first electrode tab. Furthermore, the smaller overall area of ​​the elongated second portions helps increase the area of ​​the first portions, satisfying the size relationship between the projected areas of the first and second portions, thereby improving the welding strength and welding effect of the first weld.

[0015] In some embodiments, the battery cell further includes a first electrode lead disposed on the casing. The first electrode lead is welded to a plurality of first tabs to form a second welded portion, which is connected to the first welded portion. Because the interlayer gaps between the plurality of first tabs in the first welded portion are small, the second welded portion is easy to form and less prone to defects such as incomplete soldering or porosity. Furthermore, at the connection point between the second welded portion and the first welded portion, the first tabs are less likely to break, which helps to improve the current-carrying capacity between the first tabs and the first electrode lead, reduces the risk of connection failure between the first tabs and the first electrode lead, and improves the reliability of the battery cell.

[0016] In some embodiments, at least a portion of the first weld portion surrounds and is directly connected to the second weld portion. This reduces necking at the junction of the second and first weld portions, further lowering the risk of cracking of the first electrode tab.

[0017] In some embodiments, at least a portion of the outer periphery of the second weld portion is directly connected to the first portion. The interlayer gap of the plurality of first tabs in the first portion is smaller than the interlayer gap of the plurality of first tabs in the second portion. Since at least a portion of the outer periphery of the second weld portion is directly connected to the first portion, cracks and first tab cracking are less likely to occur at the location where the second weld portion is directly connected to the first portion.

[0018] In some embodiments, there are multiple first portions, which are spaced apart along the outer periphery of the second weld portion, and adjacent first portions are connected by second portions. This increases the total length of the portion directly connected to the first portion at the outer periphery of the second weld portion, which helps reduce the size of the area at which cracking is likely to occur between the second weld portion and the first electrode tab, further improving the current-carrying capacity between the first electrode tab and the first electrode lead. Connecting adjacent first portions by the second portion reduces the area of ​​a single first portion, further lowering the risk of the first electrode tab tearing due to adhesion between the first weld portion and the welding device.

[0019] In some embodiments, both the first tab and the first electrode lead are made of aluminum. This significantly reduces the likelihood of connection failure between the first tab and the first electrode lead.

[0020] In some embodiments, multiple first electrodes are connected by ultrasonic welding to form a first welded portion, and multiple first electrodes and a first electrode lead are connected by laser welding to form a second welded portion. During ultrasonic welding, the first electrodes are less affected by heat; after welding, the portion of the first electrode near the first welded portion is less prone to tearing. Using laser welding can reduce the welding difficulty and increase the strength of the second welded portion.

[0021] In some embodiments, the first electrode lead includes a first electrode terminal, and a plurality of first tabs and the first electrode terminal are welded together to form a second welded portion. This eliminates the need for an adapter plate, reduces impedance and heat generation, and helps to increase the power of the battery cell.

[0022] According to a second aspect of this application, this application also provides a battery device comprising a plurality of battery cells provided according to any embodiment of the first aspect of this application.

[0023] According to a third aspect of this application, embodiments of this application also provide an electrical device, which includes a battery device provided in any embodiment of the second aspect of this application, the battery device being used to provide electrical energy. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 These are schematic diagrams of the vehicle structure provided in some embodiments of this application.

[0026] Figure 2 This is an exploded structural diagram of a battery device provided in some embodiments of this application.

[0027] Figure 3 The diagram shows the structure of a single battery cell provided in some embodiments of this application.

[0028] Figure 4 This is a cross-sectional schematic diagram of a battery cell provided in some embodiments of this application.

[0029] Figure 5 for Figure 4 A magnified structural diagram of region A in the middle.

[0030] Figure 6 This is a cross-sectional schematic diagram of a plurality of first tabs and first electrode leads of a battery cell provided in some embodiments of this application.

[0031] Figure 7 This is a schematic diagram of the structure of the first and second welded portions of a battery cell provided in some embodiments of this application.

[0032] Figure 8 A schematic diagram of the structure of the first and second welded portions of a battery cell provided in other embodiments of this application.

[0033] In the attached image:

[0034] Vehicle 1, battery pack 2, controller 3, motor 4, housing 5, battery cell 6;

[0035] Electrode assembly 10, main body 11, first electrode tab 12, bent section 121, stacked section 122, second electrode tab 13, outer shell 20, housing 21, end cap 22, first electrode lead-out member 30, second electrode lead-out member 40, first welding part 50, first portion 51, second portion 52, recess 53, first housing part 5a, second housing part 5b, accommodating space 5c, second welding part 60, outer periphery 61, edge 62, corner part 63, thickness direction X, first direction Y. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0038] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0041] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0042] In this application, "multiple" means two or more (including two).

[0043] In the embodiments of this application, "parallel" includes not only the case of absolute parallelism, but also the case of approximate parallelism as commonly understood in engineering; similarly, "perpendicular" also includes not only the case of absolute perpendicularity, but also the case of approximate perpendicularity as commonly understood in engineering.

[0044] In this embodiment of the application, the battery cell can be a secondary battery cell, which refers to a battery cell that can be used again after being discharged by recharging to activate the active materials.

[0045] A battery cell typically includes a casing and an electrode assembly disposed within the casing. The electrode assembly includes a positive electrode and a negative electrode. During the charging and discharging process of the battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. For example, the electrode assembly also includes a separator disposed between the positive and negative electrodes. The separator serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0046] The battery cell can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc., but the embodiments of this application are not limited to this.

[0047] As an example, the battery cell can be a prismatic battery cell or a battery cell of other shapes. Prismatic battery cells include square battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. This application does not have any particular limitations.

[0048] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0049] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0050] A battery device typically includes a housing for encapsulating one or more individual battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the individual battery cells.

[0051] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells into an independent module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties. The battery cell assembly can be housed within a housing by fixing the battery module within the housing. As an example, the housing can include a top cover, a frame, and a bottom plate. The top cover and bottom plate are respectively connected to the frame, creating a closed space inside the housing to house the battery cell assembly.

[0052] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0053] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0054] A typical battery cell includes an electrode assembly, a housing, and electrode leads. The electrode assembly is housed within the housing, and the electrode leads are located within the housing. The electrode assembly includes tabs that connect to the electrode leads. The electrode leads are used to electrically connect the electrode assembly to an external circuitry within the battery cell, enabling the charging or discharging of the battery cell.

[0055] To improve current carrying capacity, multiple tabs are typically used, stacked and welded together. However, large gaps exist between the welded tabs, affecting weld strength and stability. Furthermore, after multiple tabs are welded to the electrode leads, these large gaps can cause weld porosity and tab cracking, affecting the connection stability between the tabs and the electrode leads, thus impacting the reliability of the battery cell.

[0056] In view of this, the present application provides a technical solution in which the area of ​​the first part of the first welded part formed by welding multiple tabs is set to be larger than the area of ​​the second part of the first welded part, the thickness of the first part is smaller than the thickness of the second part, the degree of compaction of the multiple tabs in the first part is greater than the degree of compaction in the second part, and the area of ​​the multiple tabs with a greater degree of compaction is larger. Therefore, the interlayer gap of the multiple tabs in the first welded part can be reduced, and the welding strength and stability between the multiple tabs can be improved. In addition, the risk of the tabs tearing during the welding process can be reduced, and the current carrying capacity and connection stability between the tabs and the electrode leads can be improved, thereby improving the reliability of the battery cell.

[0057] The technical solutions improved in the embodiments of this application can be used in battery devices and electrical equipment that uses battery devices as power sources or various energy storage systems that use battery devices as energy storage elements.

[0058] Electrical devices can include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0059] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0060] Figure 1 This is a schematic diagram of the vehicle structure provided for some embodiments of this application. (Refer to...) Figure 1 The vehicle 1 includes a battery device 2, which may be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0061] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0062] In some embodiments of this application, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0063] Figure 2 This is an exploded structural diagram of a battery device provided in some embodiments of this application. (Refer to...) Figure 2 The battery device 2 includes a housing 5 and battery cells 6, with the battery cells 6 housed within the housing 5.

[0064] The housing 5 is used to house the battery cell 6, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the battery cell 6. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can be various shapes, such as cylinders, cuboids, etc.

[0065] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0066] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0067] In the battery device 2, there can be one or more battery cells 6. If there are multiple battery cells 6, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 6 are connected in both series and parallel. Multiple battery cells 6 can be directly connected in series, in parallel, or in a mixed configuration, and then the whole assembly of multiple battery cells 6 is housed in the housing 5. Alternatively, multiple battery cells 6 can first be connected in series, in parallel, or in a mixed configuration to form a battery module, and then multiple battery modules can be connected in series, in parallel, or in a mixed configuration to form a whole assembly, which is then housed in the housing 5.

[0068] Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application. Figure 4 This is a cross-sectional schematic diagram of a battery cell provided in some embodiments of this application. Figure 5 for Figure 4 A magnified structural diagram of region A in the middle. Figure 6 This is a cross-sectional schematic diagram of multiple first tabs and first electrode leads of a battery cell provided in some embodiments of this application. Figure 7 This is a schematic diagram of the structure of the first and second welded portions of a battery cell provided in some embodiments of this application. Figure 8 A schematic diagram of the structure of the first and second welded portions of a battery cell provided in other embodiments of this application.

[0069] Reference Figures 3 to 8This application provides a battery cell 6, which includes a housing 20 and an electrode assembly 10, with the electrode assembly 10 housed within the housing 20.

[0070] The electrode assembly 10 includes a positive electrode and a negative electrode. During the charging and discharging process of the battery cell 6, active ions (e.g., lithium ions) repeatedly insert and extract between the positive and negative electrodes. Optionally, the electrode assembly 10 also includes a separator disposed between the positive and negative electrodes, which can reduce the risk of short circuit between the positive and negative electrodes while allowing active ions to pass through.

[0071] The outer casing 20 is used to encapsulate the electrode assembly 10 and electrolyte components. The outer casing 20 can be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0072] In some embodiments, the positive electrode includes a positive electrode sheet. The positive electrode sheet may include a positive electrode current collector and a layer of positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0073] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0074] In some embodiments, the negative electrode includes a negative electrode sheet. The negative electrode sheet may include a negative electrode current collector and a layer of negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0075] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0076] In some embodiments, the electrode assembly 10 further includes a separator for separating the positive and negative electrode plates. The separator can reduce the risk of short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0077] In some embodiments, the separator includes a separator membrane. The separator membrane in this application can be any known porous structure separator membrane with good chemical and mechanical stability.

[0078] In some embodiments, the electrode assembly 10 is a wound structure. Exemplarily, both the positive and negative electrode sheets are strip structures, and the positive electrode sheet, the separator, and the negative electrode sheet are wound into a wound structure.

[0079] In some embodiments, the electrode assembly 10 has a stacked structure.

[0080] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0081] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0082] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0083] In some embodiments, the electrode assembly 10 may be cylindrical, flat, or polygonal, etc.

[0084] In some embodiments, the housing 20 includes a housing 21 and an end cap 22, the housing 21 having an opening and the end cap 22 for closing the opening.

[0085] The housing 21 is a component used to fit the end cap 22 to form the internal cavity of the battery cell 6. The formed internal cavity can be used to accommodate the electrode assembly 10, electrolyte, and other components.

[0086] The housing 21 and the end cap 22 can be separate components. For example, an opening can be provided on the housing 21, and the end cap 22 can be used to close the opening to form an internal cavity for the battery cell 6.

[0087] The housing 21 can have various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 21 can be determined according to the specific shape and size of the electrode assembly 10. The housing 21 can be made of various materials, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, aluminum-plastic film, steel-plastic film, etc.

[0088] The shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cap 22 can be the same as or different from the material of the housing 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easily deformed when subjected to compression and impact, so that the battery cell 6 can have higher structural strength and improve reliability.

[0089] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0090] The housing 21 may be open at one end or open at both ends. In some examples, the housing 21 may be a structure with an opening on one side, and one end cap 22 is provided to cover the housing 21. In other examples, the housing 21 may also be a structure with openings on both sides, and two end caps 22 are provided, with the two end caps 22 respectively covering the two openings of the housing 21.

[0091] In some embodiments, the electrode assembly 10 includes a main body 11, a first tab 12, and a second tab 13. One of the first tab 12 and the second tab 13 is a positive tab, and the other is a negative tab. The main body 11 may include a portion of the positive electrode plate coated with an active material layer, a portion of the negative electrode plate coated with an active material layer, and a separator. The active material in the active material layer is used to undergo an electrochemical reaction with an electrolyte or the like to generate a charge-discharge process.

[0092] In some embodiments, the battery cell 6 includes a first electrode lead 30 and a second electrode lead 40 disposed on the housing 20. The first electrode lead 30 is electrically connected to a first tab 12 of the electrode assembly 10, and the second electrode lead 40 is electrically connected to a second tab 13 of the electrode assembly 10. The first electrode lead 30 and the second electrode lead 40 can be used to electrically connect the electrode assembly 10 to a circuit outside the battery cell 6 to enable charging and discharging of the electrode assembly 10. Exemplarily, at least a portion of the first electrode lead 30 and the second electrode lead 40 is exposed to the outside of the battery cell 6 to facilitate connection with other components (e.g., a busbar) to extract the electrical energy generated by the electrode assembly 10.

[0093] For example, the first electrode lead-out member 30 and the second electrode lead-out member 40 can be disposed on the end cap 22 or on the housing 21.

[0094] In some embodiments, the first tab 12 extends from the end of the main body 11 facing the first electrode lead-out member 30. The second tab 13 extends from the end of the main body 11 facing the second electrode lead-out member 40.

[0095] In some examples, the first electrode lead-out 30 and the second electrode lead-out 40 may be located on the same side of the main body 11, or they may be located on opposite sides of the main body 11.

[0096] In some embodiments, the battery cell 6 includes an electrode assembly 10 and a housing 20. The electrode assembly 10 is housed within the housing 20 and includes a main body 11 and a plurality of first tabs 12 extending from the main body 11. The plurality of first tabs 12 are stacked and welded together to form a first weld portion 50. The first weld portion 50 includes at least one first portion 51 and at least one second portion 52, wherein the thickness of the first portion 51 is less than the thickness of the second portion 52. Along the thickness direction X of the first weld portion 50, the sum of the projected areas of all the first portions 51 is greater than the sum of the projected areas of all the second portions 52.

[0097] The first part 51 and the second part 52 can be formed by a single welding process. That is, the first part 51 and the second part 52 are formed in the same welding process. Optionally, the first welded part 50 can be formed by welding multiple first tabs 12 using a welding device with welding teeth. The part corresponding to the welding teeth is compacted to a greater degree, forming the first part 51 with a smaller thickness; the part not corresponding to the welding teeth is compacted to a lesser degree, forming the second part 52 with a larger thickness. Both the first part 51 and the second part 52 are relatively flat structures without pits or grooves.

[0098] The first welding portion 50 may have a recess 53, which is provided correspondingly to the first portion 51 along the thickness direction X of the first welding portion 50. The recess 53 is formed by the first portion 51 and the second portion 52. For example, the recess 53 may be a welding groove of the first welding portion 50.

[0099] The recess 53 may be formed on one side of the first welded portion 50 along its own thickness direction X, or it may be formed on both sides of the first welded portion 50 along its thickness direction X.

[0100] The thickness of the first portion 51 can be uniform or non-uniform. The thickness of the second portion 52 can be uniform or non-uniform. In this embodiment, the thickness of the first portion 51 being less than the thickness of the second portion 52 means that the average thickness of the first portion 51 is less than the average thickness of the second portion 52.

[0101] Along the thickness direction X of the first welded portion 50, the projected areas of each first portion 51 can be the same or different; the projected areas of each second portion 52 can be the same or different; the projected shapes of each first portion 51 can be the same or different; and the projected shapes of each second portion 52 can be the same or different.

[0102] When there are multiple first parts 51 and second parts 52, along the thickness direction X of the first welded part 50, the projected area of ​​a single first part 51 can be greater than, equal to or less than the projected area of ​​a single second part 52.

[0103] The thickness of the first part 51 is less than the thickness of the second part 52. The degree to which the multiple first tabs 12 are compacted in the first part 51 is greater than the degree to which the multiple first tabs 12 are compacted in the second part 52. The sum of the projected areas of each first part 51 is greater than the sum of the projected areas of each second part 52. The area occupied by the multiple first tabs 12 with a greater degree of compaction is larger, which can reduce the interlayer gap of the multiple first tabs 12 in the first welding part 50 as a whole, and improve the welding strength and stability between the multiple first tabs 12.

[0104] Furthermore, the areas occupied by the first tabs 12 with a greater degree of compaction are larger, and the area of ​​the first tabs 12 in contact with the welding teeth of the welding device is larger, which can reduce the risk of cracking of the first tabs 12 during the welding process, and help improve the current carrying capacity of the first tabs 12 and improve the reliability of the battery cell 6.

[0105] In the second part 52, the multiple first tabs 12 are less compacted, the second part 52 is less likely to stick to the welding device, and the first welding part 50 as a whole is easy to detach from the welding device. This helps to reduce the risk of the first tabs 12 tearing when the first welding part 50 detaches from the welding device due to the large adhesion between the first welding part 50 and the welding device.

[0106] In some embodiments, a gap exists between at least partially adjacent first tabs 12 in the first portion 51. In other words, the average gap between the plurality of first tabs 12 in the first portion 51 is greater than zero.

[0107] In the second part 52, there is a gap between at least some of the adjacent first electrodes 12. The average gap between the plurality of first electrodes 12 in the first part 51 is smaller than the average gap between the plurality of first electrodes 12 in the second part 52.

[0108] In the first part 51, the interlayer gaps of the plurality of first electrodes 12 can be uniform or non-uniform. For example, the interlayer gaps between the outermost first electrodes 12 are relatively small, while the interlayer gaps between the middle first electrodes 12 are relatively large. Optionally, the interlayer gaps between the plurality of first electrodes 12 can gradually decrease from the outside to the inside. Furthermore, in the arrangement direction of the second part 52 and the first part 51, the interlayer gaps of the plurality of first electrodes 12 are relatively large in the outer region of the first part 51 near the second part 52, and relatively small in the middle region of the first part 51 away from the second part 52.

[0109] The multiple first tabs 12 are compacted to a greater extent in the first portion 51, which is beneficial to improving welding strength and stability. However, if the multiple first tabs 12 are over-compacted, for example, in the first portion 51 where there are almost no gaps between the multiple first tabs 12, the first tabs 12 are more prone to fracture and failure. In the first portion 51, gaps exist between at least some of the adjacent first tabs 12, which can reduce the risk of fracture and failure of the first tabs 12, and can also reduce the welding power during the welding process of multiple first tabs 12, thereby improving welding efficiency.

[0110] In some embodiments, in the first portion 51, the average gap between the plurality of first tabs 12 is d1; in the second portion 52, the average gap between the plurality of first tabs 12 is d2; 100≥d2 / d1≥5.

[0111] Optionally, d2 / d1 can be 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100.

[0112] If d2 / d1 is too small, the degree of compaction of the first part 51 relative to the second part 52 is not significant. Even if the projected area of ​​the first part 51 is larger, the effect of reducing the overall interlayer gap of the first welded part 50 is not obvious, affecting the welding effect and welding strength. If d2 / d1 is too large, the thickness difference between the first part 51 and the second part 52 is too large, and the first electrode tab 12 is prone to breakage and failure at the connection between the first part 51 and the second part 52.

[0113] In this embodiment, the ratio of the average gap of the plurality of first tabs 12 in the second part 52 to the average gap in the first part 51 is set to 5-100. This not only helps to reduce the interlayer gap of the first welding part 50 as a whole, improve the welding effect and welding strength, but also reduces the risk of the first tabs 12 breaking during the welding process.

[0114] In some embodiments, 20 ≥ d2 / d1 ≥ 10.

[0115] Optionally, d2 / d1 can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0116] In this embodiment, the ratio of the average gap of the plurality of first tabs 12 in the second part 52 to the average gap in the first part 51 is set to 10-20, which can better balance the interlayer gap of the first welded part 50 as a whole and the structural stability of the first tabs 12.

[0117] In some embodiments, in the first portion 51, the average gap between the plurality of first tabs 12 is d1, where 3 μm ≥ d1 > 0.

[0118] Optionally, d1 can be 0.1μm, 0.5μm, 1.0μm, 1.5μm, 2.0μm, 2.5μm or 3.0μm.

[0119] In the first part 51, the average gap between the multiple first tabs 12 is too large, which may prevent effective welding between the multiple first tabs 12 and affect the welding effect. In this embodiment, the average gap between the multiple first tabs 12 in the first part 51 is set to be less than or equal to 3 μm, which can improve the welding effect and welding strength between the multiple first tabs 12.

[0120] In some embodiments, 0.2 μm ≥ d1 ≥ 0.01 μm.

[0121] Optionally, d1 can be 0.01μm, 0.02μm, 0.04μm, 0.06μm, 0.08μm, 0.10μm, 0.12μm, 0.14μm, 0.16μm, 0.18μm or 0.20μm.

[0122] If d1 is too small, the multiple first tabs 12 will be compacted too much in the first part 51, causing the first tabs 12 to break and fail. In this embodiment, d1 is set to 0.2μm≥d1≥0.01μm, which can balance the welding effect of the multiple first tabs 12 and the structural stability of the first tabs 12.

[0123] In some embodiments, in the second part 52, the average gap between the plurality of first tabs 12 is d2, 5μm≥d2>0.

[0124] Optionally, d2 can be 0.1μm, 0.5μm, 1.0μm, 1.5μm, 2.0μm, 2.5μm, 3.0μm, 3.5μm, 4.0μm, 4.5μm or 5.0μm.

[0125] In the second part 52, the average gap between the plurality of first tabs 12 is too large, the thickness of the second part 52 is too large, and the thickness difference between the second part 52 and the first part 51 is large, making the connection between the first part 51 and the second part 52 prone to breakage. In this embodiment, the average gap between the plurality of first tabs 12 in the second part 52 is set to be less than or equal to 5 μm, which can reduce the thickness difference between the first part 51 and the second part 52, thus reducing the risk of breakage at the connection between the first part 51 and the second part 52.

[0126] In some embodiments, 1μm≥d2≥0.1μm.

[0127] Optionally, d2 can be 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm or 1.0μm.

[0128] If d2 is too small, the multiple first tabs 12 will be compacted to a greater extent in the second part 52, making it easy for the first welded part 50 to stick to the welding device. When the first welded part 50 detaches from the welding device, the first tabs 12 are prone to tearing. In this embodiment, d2 is set to 1μm≥d2≥0.1μm, which can simultaneously reduce the risk of breakage at the connection between the first part 51 and the second part 52, as well as the risk of tearing of the first tabs 12.

[0129] In some embodiments, along the thickness direction X, the sum of the projected areas of all the first portions 51 is S1, the sum of the projected areas of all the second portions 52 is S2, and 50 ≥ S1 / S2 > 1.

[0130] Optionally, S1 / S2 can be 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50.

[0131] If S1 / S2 is too large, the area occupied by the first welding part 50 and the first part 51 is too large, and the area occupied by the second part 52 is too small. After the multiple first tabs 12 are welded, the first welding part 50 is easy to adhere to the welding device. When the first welding part 50 is separated from the welding device, the first tab 12 is easy to tear.

[0132] In this embodiment, S1 / S2 is set to less than or equal to 50, which can appropriately increase the area of ​​the second part 52 and help reduce the risk of the first electrode tab 12 being torn when the first welding part 50 is separated from the welding device.

[0133] In some embodiments, 25 ≥ S1 / S2 ≥ 10.

[0134] Optionally, S1 / S2 can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0135] If S1 / S2 is too small, the sum of the projected areas of the first part 51 is not significantly greater than the sum of the projected areas of the second part 52, and the effect of reducing the overall interlayer gap of the first welded part 50 is not significant. In this embodiment, S1 / S2 is set to be greater than or equal to 10 and less than or equal to 25, which can take into account both the welding strength of the first welded part 50 and the structural stability of the first tab 12.

[0136] In some embodiments, there are multiple second portions 52, and the projection of the second portions 52 along the thickness direction X is elongated. Multiple second portions 52 are intersected and form a grid structure.

[0137] The first part 51 is defined by the grid formed by the intersecting arrangement of multiple second parts 52. The projection of the first part 51 along the thickness direction X can be a triangle, rectangle, parallelogram, or other suitable shape.

[0138] Multiple second parts 52 are arranged in a cross pattern, and multiple second parts 52 and multiple first parts 51 can be arranged alternately according to certain rules. The distribution of second parts 52 and first parts 51 is more uniform, which helps to reduce the adhesion between the first welding part 50 and the welding device, and further reduces the risk of tearing of the first electrode tab 12.

[0139] Furthermore, the elongated second part 52 has a smaller overall area, which helps to increase the area of ​​the first part 51, satisfying the size relationship between the projected areas of the first part 51 and the second part 52, and improving the welding strength and welding effect of the first welding part 50.

[0140] In some embodiments, the battery cell 6 further includes a first electrode lead 30 disposed on the housing 20, the first electrode lead 30 being welded to a plurality of first tabs 12 to form a second welding portion 60, and the second welding portion 60 being connected to the first welding portion 50.

[0141] In some examples, the first electrode lead 30 may include a first electrode terminal and an adapter plate, with the electrode terminal disposed on the housing 20 and the adapter plate connected to the first electrode terminal, and a plurality of first tabs 12 and the adapter plate welded together to form a second welded portion 60.

[0142] In other examples, the first electrode lead-out 30 may also include only the first electrode terminal, with multiple first tabs 12 and the first electrode terminal welded together to form a second welded portion 60.

[0143] The first welded part 50 and the second welded part 60 can be formed by the same welding process or by different welding processes.

[0144] The first welding part 50 and the second welding part 60 can be one or more.

[0145] The second welding part 60 is connected to the first welding part 50. During the operation of the battery cell 6, the current on the first tab 12 can be conducted to the first electrode lead-out member 30 through the first welding part 50 and the second welding part 60.

[0146] The second welding part 60 is connected to the first welding part 50. Since the interlayer gap of the multiple first tabs 12 of the first welding part 50 is small, the second welding part 60 is easy to form and is not prone to phenomena such as incomplete welding or porosity. Furthermore, at the connection position between the second welding part 60 and the first welding part 50, the first tabs 12 are not easy to break, which helps to improve the current carrying capacity between the first tabs 12 and the first electrode lead 30, reduce the risk of connection failure between the first tabs 12 and the first electrode lead 30, and improve the reliability of the battery cell 6.

[0147] In some embodiments, the first electrode tab 12 includes a bent section 121 and a stacked section 122. The bent section 121 is bent at one end of the stacked section 122 and connected to the main body 11. The stacked sections 122 of the plurality of first electrode tabs 12 are welded to form a first welded section 50. The stacked sections 122 of the plurality of first electrode tabs 12 and the first electrode lead-out member 30 are welded to form a second welded section 60.

[0148] By bending the first electrode tab 12, the space occupied by the first electrode tab 12 in the thickness direction X of the first welding part 50 can be reduced, thereby improving space utilization.

[0149] The bent section 121 can be bent from one end of the stacked section 122 along a first direction Y. Exemplarily, the first direction Y is perpendicular to the thickness direction X. Exemplarily, the first direction Y can be parallel to the width direction of the end cap 22.

[0150] In some embodiments, at least a portion of the first weld portion 50 surrounds and is directly connected to the second weld portion 60. In other words, the outer periphery of the second weld portion 60 is directly connected to the first weld portion 50.

[0151] In some examples, there is one first weld portion 50 and one second weld portion 60, with the first weld portion 50 surrounding the second weld portion 60.

[0152] In other examples, there is one first weld portion 50 and multiple second weld portions 60, which are spaced apart. The outer periphery of each second weld portion 60 is directly connected to the first weld portion 50, and at least a portion of the outer periphery of each second weld portion 60 is directly connected to the first portion 51. A portion of the first weld portion 50 is located between adjacent second weld portions 60.

[0153] In the first welded part 50, the interlayer gap between the multiple first tabs 12 is small. The outer periphery of the second welded part 60 is directly connected to the first welded part 50, which can reduce the necking at the junction of the second welded part 60 and the first welded part 50 and further reduce the risk of cracking of the first tabs 12.

[0154] Furthermore, during the operation of the battery cell 6, the current can be directly transmitted between the first welding part 50 and the second welding part 60, thereby shortening the conductive path, reducing resistance, improving overcurrent capacity, and reducing heat generation.

[0155] In some embodiments, at least a portion of the outer periphery 61 of the second welded portion 60 is directly connected to the first portion 51.

[0156] The entire outer periphery 61 of the second welding part 60 can be directly connected to the first part 51, or only a part of the outer periphery 61 of the second welding part 60 can be directly connected to the first part 51, and the other part of the outer periphery 61 of the second welding part 60 can be directly connected to the second part 52.

[0157] The outer periphery 61 of the second welded part 60 is a closed annular structure. Optionally, the outer periphery 61 can be a square annular ring, a circular annular ring, an elliptical annular ring, or other suitable annular shape.

[0158] The interlayer gaps between the multiple first tabs 12 in the first portion 51 are smaller than the interlayer gaps between the multiple first tabs 12 in the second portion 52. At least a portion of the outer periphery of the second weld portion 60 is directly connected to the first portion 51, and cracks or breakage of the first tabs 12 are less likely to occur at the location where the second weld portion 60 is directly connected to the first portion 51. During the operation of the battery cell 6, the current on the first tab 12 can be conducted to the first electrode lead 30 through the first portion 51 and the second weld portion 60, which helps to improve the overcurrent capacity between the first tab 12 and the first electrode lead 30, reduce the risk of connection failure between the first tab 12 and the first electrode lead 30, and improve the reliability of the battery cell 6.

[0159] In some embodiments, the second weld portion 60 includes a plurality of edges 62, which are sequentially connected to form the outer periphery 61 of the second weld portion 60. At least a portion of each edge 62 of the second weld portion 60 is directly connected to the first portion 51. Cracking is not desirable between each edge of the second weld portion 60 and the first electrode tab 12, which helps to further reduce the risk of connection failure between the first electrode tab 12 and the first electrode lead-out member 30, and improves the reliability of the battery cell 6.

[0160] In some embodiments, the outer periphery 61 of the second welded portion 60 includes a plurality of corner portions 63, each corner portion 63 being directly connected to the first portion 51. The corner portions 63 are formed at the connection position of two adjacent edges 62.

[0161] In some embodiments, there are multiple first portions 51, and the multiple first portions 51 are spaced apart along the outer periphery of the second weld portion 60.

[0162] Multiple first portions 51 are distributed around the outer periphery of the second welding portion 60, and at least some of the multiple first portions 51 are directly connected to the outer periphery of the second welding portion 60.

[0163] Two adjacent first parts 51 can be connected by the second part 52, or by the unwelded part of the first tab 12.

[0164] Multiple first portions 51 are arranged along the outer periphery of the second welding portion 60, which can increase the total length of the portion directly connected to the outer periphery of the second welding portion 60 and the first portion 51. This helps to reduce the size of the area where there is a risk of cracking between the second welding portion 60 and the first electrode tab 12, further improve the current carrying capacity between the first electrode tab 12 and the first electrode lead 30, reduce the risk of connection failure between the first electrode tab 12 and the first electrode lead 30, and improve the reliability of the battery cell 6.

[0165] In some embodiments, two adjacent first portions 51 are connected by a second portion 52.

[0166] There can be multiple second parts 52. Optionally, multiple first parts 51 and multiple second parts 52 can be alternately arranged along the outer periphery of the second welded portion 60.

[0167] The two adjacent first parts 51 are connected by the second part 52, which can reduce the area of ​​a single first part 51, further reduce the risk of the first welding part 50 sticking to the welding device, improve the smoothness of the first welding part 50 separating from the welding device, and help to further reduce the risk of the first electrode tab 12 tearing.

[0168] In some embodiments, the materials of the first tab 12 and the first electrode lead-out member 30 both include aluminum.

[0169] The first electrode 12 can be the positive electrode.

[0170] Aluminum has a large shrinkage rate after solidification. After welding, the liquid aluminum at the interface between the first electrode tab 12 and the molten pool shrinks significantly, making the weld more prone to cracking and increasing the risk of connection failure between the first electrode tab 12 and the first electrode lead-out member 30. In this embodiment, for the first electrode tab 12 and the first electrode lead-out member 30, which are made of aluminum, at least a portion of the outer periphery of the second welding part 60 is directly connected to the first welding part 50, further reducing the risk of connection failure between the first electrode tab 12 and the first electrode lead-out member 30.

[0171] In some embodiments, the first electrode lead-out member 30 includes a first electrode terminal, and a plurality of first tabs 12 are soldered to the first electrode terminal.

[0172] The first tab 12 is directly welded to the first electrode terminal, eliminating the need for an adapter plate, which reduces impedance and heat generation, and helps to improve the power of the battery cell 6.

[0173] In some embodiments, a plurality of first electrode tabs 12 are connected by ultrasonic welding to form a first welded portion 50, and a plurality of first electrode tabs 12 and a first electrode lead-out member 30 are connected by laser welding to form a second welded portion 60.

[0174] During ultrasonic welding, the first electrode tab 12 experiences less heat impact; after welding, the portion of the first electrode tab 12 near the first weld portion 50 is less prone to tearing. Laser welding can reduce welding difficulty and increase the strength of the second weld portion 60 formed by the weld.

[0175] In some embodiments, the battery cell 6 can be assembled according to the following steps: First, a plurality of first tabs 12 are ultrasonically welded to form an ultrasonic weld mark (i.e., a first welded portion 50); then, the plurality of first tabs 12 are attached to the first electrode lead 30, and a laser is irradiated on the ultrasonic weld mark from the side away from the first electrode lead 30. The laser melts a portion of the first tab 12 and a portion of the first electrode lead 30 to form a molten pool. After the molten pool solidifies, a second welded portion 60 (i.e., a laser weld mark) is formed.

[0176] According to some embodiments of this application, this application also provides a battery device 2, which includes a plurality of battery cells 6 provided in any of the above embodiments.

[0177] According to some embodiments of this application, this application also provides an electrical device, which includes a battery device 2 of any of the above embodiments, the battery device 2 being used to provide electrical energy.

[0178] This application provides a battery cell 6, which includes an electrode assembly 10, a housing 20, and a first electrode lead-out member 30 disposed on the housing 20. The electrode assembly 10 is housed within the housing 20 and includes a main body 11 and a plurality of first tabs 12 extending from the main body 11. The plurality of first tabs 12 are stacked and ultrasonically welded to form a first welded portion 50. The first electrode lead-out member 30 is welded to the plurality of first tabs 12 to form a second welded portion 60, which is connected to the first welded portion 50. The first welded portion 50 includes a plurality of first portions 51 and a plurality of second portions 52, the thickness of the first portions 51 being less than the thickness of the second portions 52. Along the thickness direction X of the first welded portion 50, the sum of the projected areas of all the first portions 51 is greater than the sum of the projected areas of all the second portions 52. In the first portions 51, at least partially adjacent first tabs 12 have gaps. In the second portions 52, at least partially adjacent first tabs 12 have gaps. The average gap of the plurality of first electrodes 12 in the first part 51 is smaller than the average gap of the plurality of first electrodes 12 in the second part 52.

[0179] In the first part 51, the average gap between the plurality of first electrodes 12 is d1; in the second part 52, the average gap between the plurality of first electrodes 12 is d2; 100 ≥ d2 / d1 ≥ 5. Optionally, 20 ≥ d2 / d1 ≥ 10.

[0180] In the first part 51, the average gap between the plurality of first tabs 12 is d1, where 3 μm ≥ d1 > 0. Optionally, 0.2 μm ≥ d1 ≥ 0.01 μm.

[0181] In the second part 52, the average gap between the plurality of first tabs 12 is d2, where 5 μm ≥ d2 > 0. Optionally, 1 μm ≥ d2 ≥ 0.1 μm.

[0182] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, include: shell; as well as An electrode assembly is housed within the housing. The electrode assembly includes a main body and a plurality of first tabs extending from the main body. The plurality of first tabs are stacked and welded together to form a first weld portion. The first weld portion includes at least one first part and at least one second part. The thickness of the first part is less than the thickness of the second part. Along the thickness direction of the first weld portion, the sum of the projected areas of all the first parts is greater than the sum of the projected areas of all the second parts.

2. The battery cell according to claim 1, characterized in that, In the first portion, there is a gap between at least some of the adjacent first electrodes; in the second portion, there is a gap between at least some of the adjacent first electrodes. The average gap between the plurality of first electrodes in the first part is smaller than the average gap between the plurality of first electrodes in the second part.

3. The battery cell according to claim 2, characterized in that, In the first part, the average gap between the plurality of first electrodes is d1; in the second part, the average gap between the plurality of first electrodes is d2. 100≥d2 / d1≥5.

4. The battery cell according to claim 3, characterized in that, 20≥d2 / d1≥10.

5. The battery cell according to any one of claims 2-4, characterized in that, In the first part, the average gap between the plurality of first electrodes is d1, 3μm ≥ d1 > 0; and / or, In the second part, the average gap between the plurality of first electrodes is d2, where 5μm ≥ d2 > 0.

6. The battery cell according to claim 5, characterized in that, 0.2μm≥d1≥0.01μm; and / or, 1μm≥d2≥0.1μm.

7. The battery cell according to any one of claims 1-6, characterized in that, Along the thickness direction, the sum of the projected areas of all the first portions is S1, the sum of the projected areas of all the second portions is S2, and 50 ≥ S1 / S2 > 1.

8. The battery cell according to claim 7, characterized in that, 25≥S1 / S2≥10.

9. The battery cell according to any one of claims 1-5, characterized in that, The second part consists of multiple parts. Along the thickness direction, the projection of the second part is a long strip shape. Multiple second parts are intersected and form a grid structure.

10. The battery cell according to any one of claims 1-9, characterized in that, The battery cell also includes a first electrode lead provided on the outer casing. The first electrode lead is welded to the plurality of first tabs to form a second welding part, and the second welding part is connected to the first welding part.

11. The battery cell according to claim 10, characterized in that, At least a portion of the first welded portion surrounds the second welded portion and is directly connected to the second welded portion.

12. The battery cell according to claim 10 or 11, characterized in that, At least a portion of the outer periphery of the second welded part is directly connected to the first part.

13. The battery cell according to any one of claims 10-12, characterized in that, The first part is multiple, and the multiple first parts are arranged at intervals along the outer periphery of the second welded part, and two adjacent first parts are connected by the second part.

14. The battery cell according to any one of claims 10-13, characterized in that, The materials of the first tab and the first electrode lead-out are both aluminum.

15. The battery cell according to any one of claims 10-14, characterized in that, The plurality of first electrodes are connected by ultrasonic welding to form the first welded part, and the plurality of first electrodes and the first electrode lead-out are connected by laser welding to form the second welded part.

16. The battery cell according to any one of claims 10-15, characterized in that, The first electrode lead-out includes a first electrode terminal, and the plurality of first tabs and the first electrode terminal are welded together to form the second welded portion.

17. A battery device, characterized in that, It includes multiple battery cells according to any one of claims 1-16.

18. An electrical appliance, characterized in that, Includes the battery device according to claim 17, the battery device being used to provide electrical energy.

Images