Battery cell, battery device, power consuming device, and energy storage device

Abstract

The application provides a battery monomer, a battery device, a power utilization device and an energy storage device, and belongs to the technical field of batteries. The battery monomer comprises an electrode assembly, and the electrode assembly comprises a first current collector, a first tab and a first active material layer. The first tab is connected with part of the surface of the first current collector, the first tab on the surface of the first current collector comprises a first area and a second area, the second area is located at least at opposite edges of the first tab, the first area is welded with the first current collector, and the second area is adhesively connected with the first current collector; the first active material layer is located on the surface of the first current collector, and the first active material layer also covers the surface of the first tab away from the first current collector. The battery monomer provided by the application solves the problem that the edge position of the first tab is prone to warping by adhesively connecting the second area of the first tab with the first current collector, and the reliability of the battery monomer is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell, battery device, power supply device, and energy storage device. Background Technology

[0002] Energy conservation and emission reduction are key to sustainable social development. Rechargeable batteries, with their ability to store and release energy as needed, are widely used in various electrical devices and energy storage systems, and are an important component in promoting energy transition and sustainable development. For the new energy industry, battery technology is a crucial factor in its development.

[0003] A battery cell includes an electrode, which may include a current collector, a tab welded to the surface of the current collector, and an active material layer coated on the surface of the current collector. In some cases, to increase the active material capacity of the electrode, an active material layer may also be coated on the side of the tab facing away from the current collector. However, the active material layer coated on the tab surface is prone to inconsistent thickness, which can affect the performance of the battery cell. Summary of the Invention

[0004] This application aims to at least solve one of the technical problems existing in the background art. To this end, one object of this application is to provide a battery cell, battery device, power consumption device, and energy storage device to solve the problem that the active material layer on the side of the electrode opposite to the current collector is prone to uneven thickness, thereby improving the performance of the battery cell.

[0005] An embodiment of the first aspect of this application provides a battery cell including an electrode assembly. The electrode assembly includes a first current collector, a first tab, and a first active material layer. The first tab is partially connected to the surface of the first current collector. The first tab located on the surface of the first current collector includes a first region and a second region. The second region is located at least at two opposite edges of the first tab. The first region is welded to the first current collector, and the second region is bonded to the first current collector. The first active material layer is located on the surface of the first current collector and also covers the surface of the first tab opposite to the first current collector.

[0006] In the technical solution of this application embodiment, a first active material layer is covered on the surface of the first tab away from the first current collector. This not only increases the active material capacity of the battery cell and improves charge and discharge performance, but also covers the burrs generated on the surface of the first tab due to welding of the first tab and the first current collector, reducing the damage caused by burrs to other structures in the electrode assembly. The welding connection between the first region and the first current collector facilitates better electrical transmission performance between the first tab and the first current collector. The second region of the first tab is bonded to the first current collector, which fixes the two opposite edges of the first tab to the surface of the first current collector, thereby making the first tab fit snugly against the surface of the first current collector. This reduces the likelihood of the edge of the first tab lifting due to thermal stress generated during the welding connection of the first region and the first current collector, thus maintaining a relatively flat surface on the side of the first tab away from the first current collector. This ensures a consistent thickness of the first active material layer coated on the side of the first tab away from the first current collector, resulting in consistent volume changes of the first active material layer during charging and discharging, and a more uniform stress distribution in the first active material layer. This reduces the risk of the first active material layer detaching from the surface of the first tab, thereby improving the safety and performance of the battery cell.

[0007] In some embodiments, the first tab includes a first surface connected to the surface of the first current collector, wherein the first surface of the second region is recessed relative to the first surface of the first region in a direction away from the first current collector to form a recessed structure. The electrode assembly also includes an adhesive layer located within the recessed structure and connecting the second region and the first current collector. Forming a recessed structure on the first surface of the first tab can accommodate the adhesive layer, which can, to some extent, prevent the surface of the second region away from the first current collector from protruding beyond the surface of the first region away from the first current collector due to the presence of the adhesive layer. This maintains a relatively flat surface of the first tab away from the first current collector, thereby ensuring that the thickness of the first active material layer coated on the surface of the first tab remains consistent and improving the performance of the battery cell.

[0008] In some embodiments, the adhesive layer is made of conductive adhesive. The adhesive layer is both adhesive and conductive, and it also allows a current path to be formed between the second region and the first current collector, increasing the current conduction area between the first tab and the first current collector, thereby improving the electrical transmission capacity between the first tab and the first current collector and thus enhancing the charge-discharge performance of the battery cell.

[0009] In some embodiments, the second region is located on opposite sides of the first region and is connected to the opposite side edges of the first region respectively. Since a weld mark will be formed at the contact point between the first region and the first current collector after welding, the edge of the first region, which is also the edge of the weld mark, is prone to lifting due to stress concentration. By connecting the first region and the second region, after the second region is bonded to the first current collector, it is equivalent to the edge of the weld mark being bonded to the first current collector, thereby further improving the problem of the edge of the first electrode being prone to lifting and improving the flatness of the surface of the first electrode away from the first current collector.

[0010] In some embodiments, the first region and the second region extend along a first direction, and the length of the second region is greater than or equal to the length of the first region along the first direction. This ensures that the length of the second region is sufficiently large to prevent the first tabs on both sides of the first region from warping, thereby further mitigating the problem of the first tab edges easily warping.

[0011] In some embodiments, along the first direction, the length of the second region is greater than or equal to the length of the first active material layer. This ensures, to a certain extent, that the first active material layer is located in a flat area on the surface of the first electrode, thereby improving the uniformity of the thickness of the first active material layer on the surface of the first electrode.

[0012] In some embodiments, the first region includes a first side edge flush with one edge of the first active material layer, and a second region surrounds the remaining sides of the first region other than the first side edge. The second region surrounding the remaining sides of the first region increases the bonding area between the second region and the first current collector, improves bonding strength, and effectively suppresses warping of the solder joint edge due to stress concentration. The first side edge being flush with one edge of the first active material layer and welded to the first current collector facilitates the extraction of electrical signals from the electrode assembly from the first side edge, improving current transmission performance.

[0013] In some embodiments, along the relative directions of the second regions located on opposite sides of the first region, the ratio of the length of the first region to the total length of the second region is greater than or equal to 0.5 and less than or equal to 2. Within this range, on the one hand, the welding area of ​​the first region is relatively large, maintaining good current transmission capability between the first electrode and the first current collector. On the other hand, it also ensures that the area of ​​the second region is not too small, allowing the second region to achieve good bonding with the first current collector, thereby effectively improving the problem of the second region being prone to warping.

[0014] In some embodiments, a first current collector and a first active material layer located on the surface of the first current collector are wound together to form a first wound structure. The first tab includes a first portion and a second portion adjacent to each other along the axial direction of the first wound structure. The first portion and the second portion are located in the first portion, and the second portion extends out of the first wound structure. This facilitates current conduction between the electrode assembly and the external circuitry through the second portion, improving the performance of the battery cell.

[0015] In some embodiments, the second region is located at least on opposite sides of the first region, and the first region and the second region located on opposite sides of the first region extend along the axial direction of the first winding structure. This allows the circumferential tension and axial contraction force generated by the first tab during winding to be evenly distributed to the second regions on both sides, reducing the risk of the first tab easily lifting or falling off due to stress concentration on one side.

[0016] In some embodiments, the first active material layer covering the surface of the first tab facing away from the first current collector is referred to as the first sublayer. Along the winding direction of the first winding structure, the minimum distance between the surface of the first tab facing away from the first current collector and the surface of the first sublayer facing away from the first current collector is equal at all points. That is, along the winding direction of the first winding structure, the thickness of the first sublayer located on the surface of the first tab is equal everywhere. During charging and discharging, the uniformly thick first sublayer can expand uniformly and generate uniformly distributed stress, reducing the risk of stress concentration caused by local thickness differences in the first sublayer leading to peeling of the first sublayer and the first tab. Furthermore, a uniformly thick first sublayer can also reduce problems such as interlayer misalignment, wrinkles, or compression caused by thickness differences during winding, improving the reliability and safety of the battery cell.

[0017] In some embodiments, the minimum distance between each point on the surface of the first region and the second region facing away from the first current collector and the surface of the first current collector is equal. This makes the surface of the first electrode facing away from the first current collector flat relative to the first current collector, which can improve the thickness uniformity of the first active material layer on the surface of the first electrode facing away from the first current collector.

[0018] In some embodiments, the maximum value of the total thickness of the first tab and the first active material layer covering the surface of the first tab is less than or equal to the minimum value of the thickness of the first active material layer covering the surface of the first current collector. This ensures that the total thickness of the first tab and the first active material layer covering the first tab is less than or equal to the thickness of the first active material layer on the periphery, reducing the risk of excessive overall thickness at the first tab location causing compression of other structures in the electrode assembly and improving the safety of the battery cell.

[0019] In some embodiments, the ratio of the maximum thickness of the first tab to the maximum thickness of the first active material layer is greater than or equal to 0.5 and less than 1. Within this range, on the one hand, the thickness of the first tab can be kept relatively large to ensure the current transmission performance between the first current collector and the first tab. On the other hand, the thickness of the first tab is not too large, which reduces the risk of the first tab compressing other structures in the electrode assembly, and also leaves space for coating the first active material layer on the surface of the first tab opposite to the first current collector, thereby improving the energy density of the battery cell.

[0020] In some embodiments, a first active material layer and a first tab are provided on both opposite surfaces of the first current collector. This not only increases the capacity of the electrode assembly but also improves the current transmission capability between the first current collector and the external circuit, thereby increasing the charge and discharge efficiency of the battery cell.

[0021] In some embodiments, the first active material layer is a cathode active material layer. Since the first tab is connected to the surface of the first current collector, it occupies part of the surface of the first current collector, reducing the volume of the cathode active material layer covering the first current collector. That is, it reduces the capacity of the cathode active material layer to a certain extent, so that the anode active material layer directly opposite the position of the first tab has sufficient capacity for lithium intercalation, which can avoid the problem of lithium plating in the electrode assembly to a certain extent.

[0022] In some embodiments, the electrode assembly further includes a second current collector, an anolyte layer, and a second tab. The anolyte layer is located on a portion of the surface of the second current collector; the second tab is located at the beginning and / or end of the surface of the second current collector and at least one side of the anolyte layer. When the first and second current collectors are wound together to form a wound structure, since there is ample space at both the beginning and end of the second current collector to accommodate the second tab, sufficient space can be provided for the expansion of the electrode assembly at the second tab. This reduces the likelihood of compression or damage to other structures in adjacent electrode assemblies due to the presence of the second tab or burrs on its surface. Consequently, the surface of the second tab facing away from the second current collector does not need to be coated with an anolyte layer, simplifying the manufacturing process of the electrode assembly.

[0023] An embodiment of the second aspect of this application provides a battery device that includes the battery cell described in the above embodiments.

[0024] An embodiment of the third aspect of this application provides an electrical device that includes the battery device described in the above embodiments, the battery device being used to provide electrical energy.

[0025] An embodiment of the fourth aspect of this application provides an energy storage device, which includes the battery device in the above embodiments, the battery device being used to store electrical energy.

[0026] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0027] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0028] Figure 1 This is a schematic diagram of the vehicle structure according to some embodiments of this application;

[0029] Figure 2 This is an exploded structural diagram of a battery cell according to some embodiments of this application;

[0030] Figure 3 This is a cross-sectional view of the first current collector and the first active material layer in a laid-out state according to some embodiments of this application;

[0031] Figure 4 This is one of the top view structural diagrams of the first current collector and the first active material layer in a flat state according to some embodiments of this application;

[0032] Figure 5 This is a second top view of the first current collector and the first active material layer in a flat state according to some embodiments of this application;

[0033] Figure 6 This is one of the schematic diagrams of a partial end face structure of an electrode assembly in a wound state according to some embodiments of this application;

[0034] Figure 7 This is a second schematic diagram of a partial end face structure of an electrode assembly in a wound state according to some embodiments of this application;

[0035] Figure 8 This is the third schematic diagram of a partial end face structure of an electrode assembly in a wound state according to some embodiments of this application;

[0036] Figure 9 This is a cross-sectional view of the cathode and anode plates in a flat state according to some embodiments of this application.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1000 vehicles;

[0039] Battery 100;

[0040] Controller 200;

[0041] Motor 300, Zone 1 311, Zone 2 312;

[0042] End cap 21, electrode terminal 21a, housing 22, electrode assembly 23;

[0043] First current collector 30, first electrode 31, first active material layer 32, adhesive layer 33;

[0044] Second current collector 40, anode active material layer 41, second electrode tab 42;

[0045] Diaphragm 50;

[0046] Winding direction r. Detailed Implementation

[0047] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein 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 specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0049] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0050] In this document, the term "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 throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0051] In the description of the embodiments 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, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0052] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0053] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0054] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0055] Currently, the application of rechargeable batteries is becoming increasingly widespread, judging from market trends. They are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but also extensively in various electronic devices, such as electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As the application areas of rechargeable batteries continue to expand, the market demand is also constantly increasing.

[0056] A battery cell includes an electrode, which may include a current collector, a tab connected to the surface of the current collector, and an active material layer coated on the surface of the current collector. Exemplarily, the tab may be welded to the surface of the current collector.

[0057] Because the tab welding occupies part of the current collector surface, the active material layer cannot coat all of the current collector surface, resulting in a waste of active material capacity and space. Furthermore, during the welding process between the tab and the current collector, burrs or protrusions of uneven thickness or size are easily generated on the side of the tab away from the current collector, which can easily damage surrounding structures. Therefore, in order to improve the active material capacity of the battery cell and reduce the damage to other structures caused by burrs, the embodiments of this application coat the surface of the tab away from the current collector with an active material layer, increasing the volume of the active material layer, i.e., increasing the active material capacity of the electrode. At the same time, the active material layer can also cover the burrs or protrusions on the tab surface, preventing burrs from damaging other structures in the battery cell.

[0058] However, during the welding of the tab and the current collector, the edge of the tab is prone to warping due to thermal stress during welding. Therefore, when the active material layer is coated on the side of the tab away from the current collector, the thickness of the active material layer formed on the tab surface is easily uneven, affecting the performance of the battery cell.

[0059] Based on the above considerations, a battery cell is designed, comprising an electrode assembly, which includes a first current collector, a first tab, and a first active material layer. The first tab is partially connected to the surface of the first current collector. The first tab located on the surface of the first current collector includes a first region and a second region. The second region is located at least at two opposite edges of the first tab. The first region is welded to the first current collector, and the second region is bonded to the first current collector. The first active material layer is located on the surface of the first current collector, and the first active material layer also covers the surface of the first tab opposite to the first current collector.

[0060] A first active material layer is applied to the surface of the first tab away from the first current collector. This not only increases the active material capacity of the battery cell and improves charge-discharge performance, but also covers burrs generated on the surface of the first tab due to welding between the first tab and the first current collector, reducing the damage caused by burrs to other structures in the electrode assembly. Welding the first region to the first current collector facilitates better electrical transfer performance between the first tab and the first current collector. A second region of the first tab is bonded to the first current collector, fixing the two opposite edges of the first tab to the surface of the first current collector, thus ensuring the first tab fits snugly against the surface of the first current collector. This reduces the likelihood of the edges of the first tab lifting due to thermal stress generated during welding between the first region and the first current collector, maintaining a relatively flat surface on the side of the first tab away from the first current collector. This ensures a consistent thickness of the first active material layer on this side, resulting in uniform volume change and stress distribution during charge-discharge. This reduces the risk of the first active material layer detaching from the first tab surface, improving the safety and performance of the battery cell.

[0061] The battery cells disclosed in this application can be used, but are not limited to, in electrical devices or energy storage devices such as vehicles, ships, or aircraft. A power system comprising the battery cells and batteries disclosed in this application can be used to construct such an electrical device or energy storage device.

[0062] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. 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.

[0063] This application also provides an energy storage device that uses a battery as a power source. The energy storage device can be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power station, an energy storage battery pack, or a portable energy storage system.

[0064] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0065] Please refer to Figure 1 , Figure 1This is a schematic diagram of the structure of a vehicle provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. A battery 100 is disposed inside the vehicle 1000, and the battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the 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 supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0066] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0067] The battery 100 includes a housing and individual battery cells, with the individual battery cells housed within the housing. The housing provides space for the individual battery cells and can have various structures. In some embodiments, the housing may include a first portion and a second portion, which overlap each other, together defining a space for accommodating the individual battery cells.

[0068] In battery 100, there can be multiple battery cells, which can be connected in series, parallel, or a combination of both. Battery 100 may also include other structures, such as a busbar for electrical connection between multiple battery cells.

[0069] Figure 2 This is an exploded structural diagram of a battery cell according to some embodiments of this application. Figure 3 This is a cross-sectional view of the first current collector and the first active material layer in a planar state according to some embodiments of this application, with reference to... Figure 2 and Figure 3 This application provides a battery cell including an electrode assembly 23, which includes a first current collector 30, a first tab 31, and a first active material layer 32. The first tab 31 is partially connected to the surface of the first current collector 30. The first tab 31 located on the surface of the first current collector 30 includes a first region 311 and a second region 312. The second region 312 is located at least at two opposite edges of the first tab 31. The first region 311 is welded to the first current collector 30, and the second region 312 is bonded to the first current collector 30. The first active material layer 32 is located on the surface of the first current collector 30, and the first active material layer 32 also covers the surface of the first tab 31 facing away from the first current collector 30.

[0070] The battery cell can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell can be cylindrical or flat.

[0071] Please refer to Figure 2 A battery cell refers to the smallest unit that makes up a battery. For example, a battery cell includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0072] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of the battery cell from the external environment. The shape of end cap 21 may be adapted to fit the shape of housing 22. Functional components such as electrode terminals 21a may be provided on end cap 21. Electrode terminals 21a can be used for electrical connection with electrode assembly 23 to output or input electrical energy to the battery cell. In some embodiments, end cap 21 may also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell reaches a threshold. In some embodiments, an insulating member may also be provided inside end cap 21 to isolate the electrical connection components within housing 22 from end cap 21, thereby reducing the risk of short circuits.

[0073] The housing 22 is an assembly used to cooperate with the end cap 21 to form the internal environment of the battery cell, wherein the formed internal environment can be used to accommodate the electrode assembly 23, electrolyte and other components.

[0074] Electrode assembly 23 is the component in the battery cell where electrochemical reactions occur. The housing 22 may contain one or more electrode assemblies 23. Electrode assembly 23 is mainly formed by winding or stacking cathode and anode plates, and typically a separator 50 is provided between the cathode and anode plates.

[0075] In some embodiments, the first current collector 30 and the first active material layer 32 can constitute an anode sheet. The material of the first current collector 30 includes, but is not limited to, copper foil, nickel foil, carbon materials, copper / carbon composite current collectors, etc. The constituent materials of the first active material layer 32 include, but are not limited to, graphite, silicon-carbon composite materials, lithium titanate, etc.

[0076] In other embodiments, the first current collector 30 and the first active material layer 32 may also constitute a cathode sheet. The material of the first current collector 30 may include, but is not limited to, aluminum foil, copper foil, carbon nanotube film, metal / carbon composite current collector, etc. The constituent materials of the first active material layer 32 include, but are not limited to, lithium cobalt oxide, lithium iron phosphate, ternary materials, etc.

[0077] In some embodiments, the first electrode 31 may be connected to the first current collector 30 along the width direction of the first current collector 30, and the first electrode 31 may be located at the middle position of the first current collector 30.

[0078] In other embodiments, the first tab 31 may also be connected to the first current collector 30 along the length direction of the first current collector 30, and the first tab 31 may be located at the middle position of the first current collector 30. The electrode assembly 23 may be a wound structure, wherein the first current collector 30 may be wound along the length direction to form a wound structure.

[0079] In some embodiments, the first tab 31 may be fully connected to the surface of the first current collector 30, that is, the first tab 31 may be fully located on the surface of the first current collector 30.

[0080] In other embodiments, a portion of the first tab 31 is connected to the surface of the first current collector 30. In other words, a portion of the first tab 31 extends beyond one edge of the first current collector 30.

[0081] The first region 311 is the area on the first tab 31 that is welded to the first current collector 30, and the second region 312 is the area on the first tab 31 that is bonded to the first current collector 30. That is, both the first region 311 and the second region 312 belong to the areas on the surface of the first current collector 30 within the first tab 31. The area on the surface of the first current collector 30 may only include the first region 311 and the second region 312; that is, the remaining area on the surface of the first current collector 30, excluding the first region 311, constitutes the second region 312. Alternatively, a portion of the area on the surface of the first current collector 30 may include both the first region 311 and the second region 312; that is, the remaining area on the surface of the first current collector 30, excluding the first region 311, may include not only the second region 312, but may also include a third region, which may be an area not bonded to the surface of the first current collector 30. It is understandable that, while the first region 311 and the second region 312 are connected to the first current collector 30, the third region can maintain a fixed positional relationship with the surface of the first current collector 30 even if it is not connected to the surface of the first current collector 30.

[0082] In some embodiments, the second region 312 may be located only at the two opposite edges of the first electrode 31. Exemplarily, the width direction of the first electrode 31 is perpendicular to the length direction, and the second region 312 may be located at the two edges in the width direction of the first electrode 31, or at the two edges in the length direction of the first electrode 31.

[0083] In other embodiments, the second region 312 may be located at the three edges of the first tab 31.

[0084] In some other embodiments, the second region 312 may be located at the four edges of the first tab 31.

[0085] The first region 311 may be located between the two second regions 312, and the edge of the first region 311 near the second region 312 and the edge of the second region 312 near the first region 311 may be at least partially in contact. Alternatively, the edge of the first region 311 near the second region 312 and the edge of the second region 312 near the first region 311 may not be in contact, that is, there is a portion of the area between the first region 311 and the second region 312 that is not in contact with the surface of the first current collector 30.

[0086] In some embodiments, the welding connection between the first region 311 and the first current collector 30 includes, but is not limited to, arc welding, laser welding, resistance welding, ultrasonic welding, and soft soldering.

[0087] The second region 312 and the first current collector 30 can be connected by adhesives or other adhesive substances. In some embodiments, the bonding method between the second region 312 and the first current collector 30 includes, but is not limited to, solvent bonding, hot melt bonding, pressure-sensitive bonding, and photocuring bonding.

[0088] The first active material layer 32 can cover two opposing surfaces of the first current collector 30. The first tab 31 can be located in a portion of one surface of the first current collector 30. The first active material layer 32 covers the surface of the first current collector 30 without the first tab 31, and also covers the surface with the first tab 31. The first active material layer 32 covering the surface of the first current collector 30 and the first active material layer 32 covering the surface of the first tab 31 opposite to the first current collector 30 can be integrally formed.

[0089] In the above technical solution, a first active material layer 32 is covered on the surface of the first tab 31 away from the first current collector 30. This not only increases the active material capacity of the battery cell and improves charge and discharge performance, but also covers the burrs generated on the surface of the first tab 31 due to the welding of the first tab 31 and the first current collector 30, reducing the damage caused by burrs to other structures in the electrode assembly 23. The first region 311 is welded to the first current collector 30, which is beneficial to achieving better electrical transmission performance between the first tab 31 and the first current collector 30. The second region 312 of the first tab 31 is bonded to the first current collector 30, which can fix the two opposite edges of the first tab 31 to the surface of the first current collector 30, so that the first tab 31 is completely attached to the surface of the first current collector 30. This reduces the likelihood of the edge of the first tab 31 lifting due to thermal stress generated during the welding connection of the first region 311 and the first current collector 30, thus maintaining a relatively flat surface on the side of the first tab 31 away from the first current collector 30. This ensures a consistent thickness of the first active material layer 32 coated on the side of the first tab 31 away from the first current collector 30, resulting in consistent volume change of the first active material layer 32 during charging and discharging, and a more uniform stress distribution in the first active material layer 32. This reduces the risk of the first active material layer 32 detaching from the surface of the first tab 31, thereby improving the safety and performance of the battery cell.

[0090] According to some embodiments of this application, the first electrode tab 31 includes a first surface connected to the surface of the first current collector 30, wherein the first surface of the second region 312 is recessed in a direction away from the first surface of the first region 311 to form a recessed structure, and the electrode assembly 23 further includes an adhesive layer 33 located within the recessed structure and connecting the second region 312 and the first current collector 30.

[0091] The first tab 31 also includes a second surface opposite to the first surface, and the first active material layer 32 covers the second surface.

[0092] When the first current collector 30 is in a flat state, the second surface can be a flat surface. The first surface of the second region 312 is recessed towards the direction close to the second surface. That is to say, the distance between the first surface and the second surface of the second region 312 is smaller than the distance between the first surface and the second surface of the first region 311. In other words, the thickness of the second region 312 is smaller than the thickness of the first region 311.

[0093] In some embodiments, the minimum spacing between the first surface and the second surface of the second region 312 is equal everywhere. That is, in the flat state of the first current collector 30, the first surface of the second region 312 is parallel to the first current collector 30, and the cross-sectional shape of the resulting recessed structure is strip-shaped.

[0094] For example, along the thickness direction of the first current collector 30, the cross-sectional shape of the first tab 31 is similar to that of a T-shape.

[0095] In some embodiments, along the length of the first current collector 30, the edge of the adhesive layer 33 does not extend beyond the edge of the first tab 31. That is, the adhesive layer is located only within the recessed structure. The adhesive layer can fill the recessed structure.

[0096] In some embodiments, the thickness of the adhesive layer 33 may be equal to the depth of the recessed structure.

[0097] In some embodiments, the adhesive layer 33 is composed of materials including, but not limited to, viscous substances such as polyvinyl alcohol, polyacrylate, epoxy resin, phenolic resin, rubber, silicates, and phosphates.

[0098] In the above technical solution, a recessed structure is formed on the first surface of the first tab 31, which can be used to accommodate the adhesive layer 33. This can, to a certain extent, avoid the problem that the surface of the second region 312 away from the first current collector 30 protrudes from the surface of the first region 311 away from the first current collector 30 due to the presence of the adhesive layer 33. This keeps the surface of the first tab 31 away from the first current collector 30 relatively flat, so that the thickness of the first active material layer 32 coated on the surface of the first tab 31 can be kept consistent, thereby improving the performance of the battery cell.

[0099] In other embodiments, the first surface may not have a recessed structure; that is, in the flat state of the first current collector 30, both the first and second surfaces are flat surfaces. The surface of the first current collector 30 opposite to the second region 312 may form a groove to accommodate the adhesive layer 33, thereby achieving the adhesive connection between the second region 312 and the first current collector 30.

[0100] According to some embodiments of this application, the material of the adhesive layer 33 includes conductive adhesive.

[0101] In other words, the constituent materials of the adhesive layer 33 also include conductive substances, giving it conductivity and adhesion.

[0102] In some embodiments, a conductive filler may be added to the substrate forming the adhesive layer 33 to make the adhesive layer 33 conductive. For example, the substrate forming the adhesive layer 33 may be made of epoxy resin, polyurethane, polyimide resin, cyanate ester, or other materials. In the liquid state of the substrate, materials with good conductivity such as silver, copper, carbon, and nickel may be mixed in. Thus, after curing and molding to form the adhesive layer 33, the adhesive layer 33 has both conductivity and good adhesion.

[0103] In the above technical solution, the adhesive layer 33 has both adhesiveness and conductivity. The adhesive layer 33 can also form a current path between the second region 312 and the first current collector 30, increase the current conduction area between the first tab 31 and the first current collector 30, and improve the electrical transmission capability between the first tab 31 and the first current collector 30, thereby improving the charge and discharge performance of the battery cell.

[0104] Figure 4 This is one of the top view structural diagrams of the first current collector and the first active material layer in a flat state according to some embodiments of this application, with reference to... Figure 4 According to some embodiments of this application, the second region 312 is located on opposite sides of the first region 311 and is connected to the opposite side edges of the first region 311 respectively.

[0105] In some embodiments, there is one adhesive layer 33 on each side of the first region 311, and the adhesive layer extends along an arrangement direction perpendicular to the first region 311 and the second region 312.

[0106] In other embodiments, there are multiple adhesive layers 33 located on opposite sides of the first region 311, and the multiple adhesive layers 33 are arranged at intervals along an arrangement direction perpendicular to the first region 311 and the second region 312.

[0107] In the above technical solution, after the first region 311 and the first current collector 30 are welded together, a weld mark will be formed at the contact position between them. The edge of the first region 311, that is, the edge of the weld mark, is easily affected by stress concentration and will lift up. By setting the first region 311 and the second region 312 to be connected, after the second region 312 is bonded to the first current collector 30, it is equivalent to the edge of the weld mark being bonded to the first current collector 30. This can further improve the problem that the edge of the first electrode 31 is prone to lifting up, and is conducive to improving the flatness of the surface of the first electrode 31 away from the first current collector 30.

[0108] According to some embodiments of this application, the first region 311 and the second region 312 extend along a first direction, and along the first direction, the length of the second region 312 is greater than or equal to the length of the first region 311.

[0109] The first direction can be either the length direction or the width direction of the first current collector 30. When the first direction is the length direction of the first current collector 30, the length dimensions of both the first region 311 and the second region 312 are smaller than the length dimension of the first current collector 30 along this direction. When the first direction is the width direction of the first current collector 30, the length dimension of the second region 312 can be equal to the width dimension of the first current collector 30 along this direction.

[0110] It is understandable that, in the case where the length dimension of the second region 312 is greater than the length dimension of the first region 311 along the first direction, the first region 311 is only located in part of the region between the two second regions 312, and the remaining part of the region between the two second regions 312 may not be connected to the first current collector 30, or may be connected to the first current collector 30 by means of bonding.

[0111] In the above technical solution, the length of the second region 312 is large enough to ensure that the first electrode tabs 31 on both sides of the first region 311 will not lift up to a certain extent, thereby further improving the problem that the edges of the first electrode tabs 31 are prone to lifting up.

[0112] According to some embodiments of this application, along the first direction, the length of the second region 312 is greater than or equal to the length of the first active material layer 32.

[0113] The length of the second region 312 is greater than or equal to the length of the first active material layer 32 covering the surface of the first electrode 31 facing away from the first current collector 30. The width of the first active material layer 32 in the direction pointing from the second region 312 to the first region 311 can be consistent.

[0114] In the above technical solution, the first active material layer 32 can be ensured to a certain extent to be located in a flat area on the surface of the first electrode 31, thereby improving the uniformity of the thickness of the first active material layer 32 on the surface of the first electrode 31.

[0115] Figure 5 This is a second top view schematic diagram of the first current collector and the first active material layer in a flat state according to some embodiments of this application, with reference to... Figure 5 According to some embodiments of this application, the first region 311 includes a first side edge that is flush with one edge of the first active material layer 32, and the second region 312 is disposed around the remaining sides of the first region 311 other than the first side edge.

[0116] For example, the first side is flush with one of the length edges of the first active material layer 32. Along the width direction of the first active material layer 32, the length of the first region 311 is less than the width of the first active material layer 32.

[0117] In some embodiments, the first region 311 includes three sides in addition to the first side.

[0118] The second zone 312 is connected to the remaining sides of the first zone 311 except for the first side, and the second zone 312 forms a U-shaped structure around the side of the first zone 311.

[0119] In the above technical solution, the second region 312 surrounds the remaining sides of the first region 311 (excluding the first side), which increases the bonding area between the second region 312 and the first current collector 30, improves the bonding strength, and effectively suppresses the lifting of the solder joint edge due to stress concentration. The first side is flush with one edge of the first active material layer 32, and the first side is welded to the first current collector 30, which facilitates the extraction of electrical signals from the electrode assembly 23 from the first side, improving current transmission performance.

[0120] According to some embodiments of this application, along the relative directions of the second region 312 located on opposite sides of the first region 311, the ratio of the length of the first region 311 to the total length of the second region 312 is greater than or equal to 0.5 and less than or equal to 2.

[0121] The total length of the second zone 312 refers to the sum of the lengths of the two second zones 312 located on opposite sides of the first zone 311. It is understood that the second zones 312 may be located only on opposite sides of the first zone 311, or on all sides of the first zone 311 except for the first side, or they may be arranged around the entire circumference of the first zone 311. In any case, the direction of the total length of the second zones 312 is the relative direction of the two second zones 312 located on opposite sides of the first zone 311. For example, when the second zones 312 are arranged around the entire circumference of the first zone 311, the relative direction along the two second zones 312 located on opposite sides of the first zone 311 can be either the width direction or the length direction of the first zone 311.

[0122] In some embodiments, the sum of the length of the first region 311 and the total length of the second region 312 is equal to the width of the first tab 31.

[0123] In some embodiments, the lengths of the second regions 312 located on opposite sides of the first region 311 may be the same along the opposite directions of the second regions 312 located on opposite sides of the first region 311.

[0124] For example, the ratio of the length of the first region 311 to the total length of the second region 312 can be 0.5, 0.7, 0.9, 1.1, 1.3, 1.4, 1.6, 1.8 or 2.

[0125] In the above technical solution, within this range, on the one hand, the welding area of ​​the first region 311 is relatively large, maintaining good current transmission capability between the first electrode 31 and the first current collector 30. On the other hand, the area of ​​the second region 312 is not too small, allowing the second region 312 to achieve good bonding connection with the first current collector 30, thereby effectively improving the problem of the second region 312 being prone to warping.

[0126] Figure 6This is one of the schematic diagrams showing a partial end face structure of the electrode assembly in a wound state according to some embodiments of this application. Figure 7 This is the second schematic diagram of a partial end face structure of the electrode assembly in the wound state according to some embodiments of this application. (Refer to...) Figure 6 and Figure 7 According to some embodiments of this application, a first current collector 30 and a first active material layer 32 located on the surface of the first current collector 30 are wound together to form a first winding structure. The first tab 31 includes a first part and a second part adjacent to each other along the axial direction of the first winding structure. A first region 311 and a second region 312 are located in the first part, and the second part extends out of the first winding structure.

[0127] The axial direction of the first winding structure refers to the extension direction of the winding center axis of the first winding structure. The first current collector 30 is wound around the winding center axis to form the first winding structure.

[0128] The first current collector 30 can be wound along its length, and the first electrode tab 31 is connected to the first current collector 30 along its width, wherein the first part is located on the surface of the first current collector 30, and the second part extends out of the first current collector 30 along its width. Figure 4 as well as Figure 5 As shown. The width direction of the first current collector 30 may be parallel to the axial direction of the first winding structure. In some embodiments, the first current collector 30 and the first active material layer 32 located on the surface of the first current collector 30 may be spirally wound to form the first winding structure.

[0129] In other embodiments, the first winding structure may also include a straight section and bent sections located at both ends of the straight section.

[0130] The first part is located on the surface of the first current collector 30. The first part and the second part are adjacent to each other at the edge of the first current collector 30.

[0131] The embodiments of this application do not limit the shape and structure of the second part.

[0132] The first and second parts can be a single, integrally formed structure.

[0133] like Figure 6 As shown, the first electrode tab 31 can be located on the concave surface of the first current collector 30. For example... Figure 7 As shown, the first electrode 31 can also be located on the convex surface of the first current collector.

[0134] The above technical solution facilitates the conduction of current between the electrode assembly 23 and the external circuit through the second part, thereby improving the performance of the battery cell.

[0135] According to some embodiments of this application, the second region 312 is located at least on opposite sides of the first region 311, and the first region 311 and the second region 312 located on opposite sides of the first region 311 extend along the axial direction of the first winding structure.

[0136] Along the winding direction r of the first winding structure, the second region 312 is located on opposite sides of the first region 311.

[0137] Along the axial direction of the first winding structure, the length of the second region 312 can be equal to the length of the first active material layer 32, and the length of the first region 311 can be less than or equal to the length of the second region 312.

[0138] In some embodiments, the second region 312 may also be located on one side of the first region 311 along the axial direction of the first winding structure, and the second region 312 located on one side of the first region 311 along the axial direction of the first winding structure extends along the winding direction.

[0139] In the above technical solution, the circumferential tension and axial contraction force generated by the first tab 31 during the winding process can be evenly distributed to the second regions 312 on both sides, reducing the risk that the first tab 31 is prone to warping or falling off due to stress concentration on one side of the first tab 31.

[0140] According to some embodiments of this application, the first active material layer 32 covering the surface of the first tab 31 facing away from the first current collector 30 is referred to as the first sublayer. Along the winding direction r of the first winding structure, the minimum distance between the surface of the first tab 31 facing away from the first current collector 30 and the surface of the first sublayer facing away from the first current collector 30 is equal.

[0141] Along the winding direction r of the first winding structure, the direction of the minimum distance between the surface of the first tab 31 facing away from the first current collector 30 and the surface of the first sublayer facing away from the first current collector 30 is the radial direction of the first winding structure. Radial is a direction perpendicular to the axial direction of the first winding structure and radiating outward from the winding center axis of the winding body.

[0142] Along the winding direction r of the first winding structure, the minimum distance between the surface of the first tab 31 facing away from the first current collector 30 and the surface of the first sub-layer facing away from the first current collector 30 is equal everywhere; that is, the thickness of the first sub-layer located on the surface of the first tab 31 is equal everywhere. In the flat state of the first current collector 30, the thickness of the first sub-layer is uniform everywhere.

[0143] In the above technical solution, that is, along the winding direction r of the first winding structure, the thickness of the first sub-layer on the surface of the first tab 31 is equal everywhere. During the charging and discharging process, the first sub-layer with uniform thickness can expand uniformly and generate uniformly distributed stress, reducing the risk of the first sub-layer and the first tab 31 peeling off due to stress concentration caused by local thickness differences of the first sub-layer. In addition, the first sub-layer with uniform thickness can also reduce problems such as interlayer misalignment, wrinkles or compression caused by thickness differences during the winding process, thereby improving the reliability and safety of the battery cell.

[0144] According to some embodiments of this application, the minimum distance between each point on the surface of the first region 311 and the second region 312 facing away from the first collector 30 and the surface of the first collector 30 is equal.

[0145] In other words, the distance between the second surface of the first tab 31 and the surface of the first current collector 30 is equal everywhere. The direction of the minimum distance between the surface of the first region 311 and the surface of the second region 312 facing away from the first current collector 30 is the radial direction of the first winding structure.

[0146] Along the winding direction r of the first winding structure, the minimum distance between the surface of the first tab 31 facing away from the first current collector 30 and the surface of the first current collector 30 is equal everywhere.

[0147] In the above technical solution, the surface of the first tab 31 facing away from the first current collector 30 is flat relative to the first current collector 30, which can improve the thickness uniformity of the first active material layer 32 on the surface of the first tab 31 facing away from the first current collector 30.

[0148] According to some embodiments of this application, the maximum value of the total thickness of the first electrode 31 and the first active material layer 32 covering the surface of the first electrode 31 is less than or equal to the minimum value of the thickness of the first active material layer 32 covering the surface of the first current collector 30.

[0149] The first active material layer 32 covering the surface of the first current collector 30 is the first active material layer 32 covering the surface of the first current collector 30 where the first tab 31 is not located. The first active material layer 32 covering the first tab 31 is the first active material layer 32 covering the first tab 31 facing away from the surface of the first current collector 30. The total thickness of the first tab 31 and the first active material layer 32 covering the first tab 31 can be equal everywhere. The thickness of the first active material layer 32 directly covering the surface of the first current collector 30 can also be equal everywhere.

[0150] For example, the total thickness of the first tab 31 and the first active material layer 32 covering the first tab 31 is equal to the thickness of the first active material layer 32 covering the surface of the first current collector 30, that is, the surface of the first active material layer 32 facing away from the first current collector 30 is flat.

[0151] In the above technical solution, the total thickness of the first tab 31 and the first active material layer 32 covering the first tab 31 is less than or equal to the thickness of the first active material layer 32 on the periphery, thereby reducing the risk of other structures in the electrode assembly 23 being squeezed due to the excessive overall thickness at the position of the first tab 31, and improving the safety of the battery cell.

[0152] According to some embodiments of this application, the ratio of the maximum thickness of the first tab 31 to the maximum thickness of the first active material layer 32 is greater than or equal to 0.5 and less than 1.

[0153] The maximum thickness of the first tab 31 is located in the first region 311. The maximum thickness of the first active material layer 32 is located in the first active material layer 32 that directly covers the surface of the first current collector 30.

[0154] In some embodiments, the ratio of the maximum thickness of the first tab 31 to the maximum thickness of the first active material layer 32 is 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 0.98.

[0155] In the above technical solution, within this range, on the one hand, the thickness of the first tab 31 can be maintained at a relatively large level to ensure the current transmission performance between the first current collector 30 and the first tab 31. On the other hand, the thickness of the first tab 31 is not too large, which can reduce the risk of the first tab 31 squeezing other structures in the electrode assembly 23, and also leaves space to coat the first active material layer 32 on the surface of the first tab 31 opposite to the first current collector 30, thereby improving the energy density of the battery cell.

[0156] Figure 8 This is the third schematic diagram of a partial end face structure of the electrode assembly in the wound state according to some embodiments of this application. Figure 9 This is a cross-sectional view of the cathode and anode plates in a flat lay-up state according to some embodiments of this application, with reference to... Figure 8 and Figure 9 According to some embodiments of this application, the first current collector 30 has a first active material layer 32 and a first tab 31 on both opposite surfaces.

[0157] In some embodiments, there are two first tabs 31, and the two first tabs 31 are located on the two sides of the same position of the first current collector 30, that is, the two first tabs 31 are overlapped.

[0158] In other embodiments, there are two first tabs 31, which are alternately arranged on both sides of the first current collector 30.

[0159] The first active material layer 32 and the first tab 31 on the two surfaces of the first current collector 30 correspond one-to-one, and the first active material layer 32 on each surface of the first current collector 30 covers the surface of the corresponding first tab 31 that is away from the first current collector 30. Each first tab 31 includes a first region 311 and a second region 312. The structure and relative position of the first region 311 and the second region 312, as well as the correspondence between the first active material layer 32 and the first tab 31 on each surface of the first current collector 30, can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0160] The above technical solution can not only increase the capacity of the electrode assembly 23, but also improve the current transmission capability between the first current collector 30 and the external circuit, thereby improving the charging and discharging efficiency of the battery cell.

[0161] According to some embodiments of this application, the first active material layer 32 is a cathode active material layer.

[0162] That is, the first current collector 30 and the first active material layer 32 constitute a cathode sheet. When the first current collector 30 and the first active material layer 32 constitute a cathode sheet, the materials of the first current collector 30 and the first active material layer 32 can be referred to the relevant descriptions in the above embodiments, and will not be repeated here.

[0163] In the above technical solution, since the first tab 31 is connected to the surface of the first current collector 30, it occupies part of the surface of the first current collector 30, reducing the volume of the cathode active material layer covering the first current collector 30, that is, reducing the capacity of the cathode active material layer to a certain extent, so that the anode active material layer 41 directly opposite the position of the first tab 31 has enough capacity for lithium intercalation, which can avoid the problem of lithium plating in the electrode assembly 23 to a certain extent.

[0164] refer to Figure 9 According to some embodiments of this application, the electrode assembly 23 further includes a second current collector 40, an anodic active material layer 41, and a second tab 42. The anodic active material layer 41 is located on a portion of the surface of the second current collector 40, and the second tab 42 is located at the beginning and / or end of the second current collector 40 and at least one side of the anodic active material layer 41.

[0165] In other words, the anode active material layer 41 does not cover the surface of the second electrode tab 42. The second current collector 40 and the anode active material layer 41 constitute the anode sheet. The cathode sheet, diaphragm 50, and anode sheet can be stacked and wound into a wound structure.

[0166] It is understood that, along the length direction of the second current collector 40, the length of the second current collector 40 is greater than the length of the anode active material layer 41 located on its surface, and the second tab 42 can be located on at least one side of the anode active material layer 41 along the length direction of the second current collector 40. The current collector 40 can be wound along its length direction to form a wound structure.

[0167] After the winding structure is formed, the first end of the second current collector 40 forms the winding start end, and the tail end of the second current collector 40 forms the winding end. Therefore, the second electrode 42 is located at the winding start end and / or winding end of the second current collector 40.

[0168] The winding start end of the second current collector 40 refers to the end at which the winding begins when the second current collector 40 is wound.

[0169] The winding end of the second current collector 40 refers to the end of the second current collector 40 that is finally wound when the winding operation is completed. It is worth noting that the winding start end and winding end referred to here do not necessarily refer to the end face of the second current collector 40, but can also be a position of the second current collector 40 near the end face.

[0170] In some embodiments, the second tab 42 may be located only at the head end of the second current collector 40. Exemplarily, the number of second tabs 42 may be one, and the second tab 42 may be located on one surface of the head end. The number of second tabs 42 may also be two, and the two second tabs 42 may be located on two opposite surfaces of the head end.

[0171] In other embodiments, the second tab 42 may be located only at the tail end of the second current collector 40. Exemplarily, the number of second tabs 42 may be one, and the second tab 42 may be located on one surface of the tail end. The number of second tabs 42 may also be two, and both second tabs 42 may be located on two opposite surfaces of the tail end.

[0172] In some other embodiments, the second tab 42 may be located at the beginning and end of the second current collector 40. Exemplarily, there may be two second tabs 42, with each second tab 42 located on a surface at the beginning and a surface at the end, respectively. Alternatively, the two opposite surfaces at the beginning may each be provided with a second tab 42, and the two opposite surfaces at the end may each be provided with a second tab 42.

[0173] The material of the second electrode 42 can be various, including but not limited to one or more metals such as copper, aluminum or nickel.

[0174] In some embodiments, the anodic active material layer 41 is coated on two opposite surfaces of the second current collector 40.

[0175] In some embodiments, the second electrode 42 can be electrically connected to the second current collector 40 by means of welding or the like.

[0176] In some embodiments, the two end edges of the cathode active material layer along the winding direction r of the first winding structure are opposite to the anode active material layer 41. That is, along the winding direction r of the first winding structure, the length of the anode active material layer is greater than or equal to the length of the cathode active material layer, and along the winding direction r, the anode active material layer 41 is correspondingly arranged with the cathode active material layer, so that lithium ions extracted from the cathode active material layer can be quickly embedded into the anode active material layer 41 opposite to it, reducing the probability of lithium plating.

[0177] Since the second tab 42 is disposed on at least one side of the anode active material layer 41 along the winding direction r of the first winding structure, the length of the second current collector 40 can be greater than the length of the first current collector 30.

[0178] In the above technical solution, when the first current collector 30 and the second current collector 40 are wound together to form a winding structure, since the first and last ends of the second current collector 40 have a large space to store the second electrode tab 42, it can provide a certain space for the expansion of the electrode assembly 23 at the second electrode tab 42. This makes it less likely that the second electrode tab 42 or the presence of burrs on the surface of the second electrode tab 42 will cause compression or damage to other structures in the adjacent electrode assembly 23. As a result, the surface of the second electrode tab 42 facing away from the second current collector 40 does not need to be coated with the anode active material layer 41, simplifying the preparation process of the electrode assembly 23.

[0179] This application provides a battery device, which includes the battery cells described in the above embodiments.

[0180] The battery device can be referred to the relevant description in the above embodiments, and will not be repeated here.

[0181] The battery device has the beneficial effects of the battery cell provided in the embodiments of this application. For details, please refer to the specific description of the battery cell in the above embodiments, which will not be repeated here.

[0182] This application provides an electrical device, which includes the battery device described in the above embodiments, and the battery device is used to provide electrical energy.

[0183] The electrical device has the beneficial effects of the battery device provided in the embodiments of this application. For details, please refer to the specific descriptions of the battery device in the above embodiments, which will not be repeated here.

[0184] This application provides an energy storage device, which includes the battery device described in the above embodiments, and the battery device is used to store electrical energy.

[0185] The energy storage device has the beneficial effects of the battery device provided in the embodiments of this application. For details, please refer to the specific descriptions of the battery device in the above embodiments, which will not be repeated here.

[0186] This application provides a battery cell including an electrode assembly 23. The electrode assembly 23 includes a first current collector 30, a first tab 31, and a first active material layer 32. The first tab 31 is partially connected to the surface of the first current collector 30. The first tab 31 located on the surface of the first current collector 30 includes a first region 311 and a second region 312. The second region 312 is located at least at two opposite edges of the first tab 31. The first region 311 is welded to the first current collector 30, and the second region 312 is bonded to the first current collector 30. The first active material layer 32 is located on the surface of the first current collector 30, and the first active material layer 32 also covers the surface of the first tab 31 facing away from the first current collector 30.

[0187] The first tab 31 includes a first surface connected to the surface of the first current collector 30, wherein the first surface of the second region 312 is recessed relative to the first surface of the first region 311 in a direction away from the first current collector 30 to form a recessed structure. The electrode assembly 23 also includes an adhesive layer 33 located within the recessed structure and connecting the second region 312 and the first current collector 30. The material of the adhesive layer 33 includes conductive adhesive.

[0188] For example, the second region 312 is located on opposite sides of the first region 311 and is connected to the opposite side edges of the first region 311 respectively.

[0189] For example, the first region 311 includes a first side that is flush with one edge of the first active material layer 32, and the second region 312 is disposed around the remaining sides of the first region 311 other than the first side.

[0190] The first region 311 and the second region 312 extend along a first direction. Along the first direction, the length of the second region 312 is greater than or equal to the length of the first region 311, and the length of the second region 312 is greater than or equal to the length of the first active material layer 32.

[0191] Along the relative directions of the second zone 312 located on opposite sides of the first zone 311, the ratio of the length of the first zone 311 to the total length of the second zone 312 is greater than or equal to 0.5 and less than or equal to 2.

[0192] A first current collector 30 and a first active material layer 32 on the surface of the first current collector 30 are wound together to form a first wound structure. A first tab 31 includes a first portion and a second portion adjacent along the axial direction of the first wound structure. A first region 311 and a second region 312 are located in the first portion, and the second portion extends out of the first wound structure. The first active material layer 32 covering the surface of the first tab 31 facing away from the first current collector 30 is referred to as a first sublayer. At each point along the winding direction r of the first wound structure, the minimum distance between the surface of the first tab 31 facing away from the first current collector 30 and the surface of the first sublayer facing away from the first current collector 30 is equal. Similarly, the minimum distance between each point on the surface of the first region 311 and the second region 312 facing away from the first current collector 30 and the surface of the first current collector 30 is equal.

[0193] The maximum total thickness of the first electrode tab 31 and the first active material layer 32 covering the first electrode tab 31 is less than or equal to the minimum thickness of the first active material layer 32 covering the surface of the first current collector 30. The ratio of the maximum thickness of the first electrode tab 31 to the maximum thickness of the first active material layer 32 is greater than or equal to 0.5 and less than 1.

[0194] The first current collector 30 has a first active material layer 32 and a first tab 31 on both opposite surfaces.

[0195] 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: Electrode assembly, the electrode assembly comprising: Episode 1: Fluids; A first electrode tab is connected to a portion of the surface of the first current collector. The first electrode tab located on the surface of the first current collector includes a first region and a second region. The second region is located at least at two opposite edges of the first electrode tab. The first region is welded to the first current collector, and the second region is bonded to the first current collector. A first active material layer is located on the surface of the first current collector, and the first active material layer also covers the surface of the first electrode tab opposite to the first current collector.

2. The battery cell according to claim 1, characterized in that, The first electrode tab includes a first surface connected to the surface of the first current collector, wherein the first surface of the second region is recessed relative to the first surface of the first region in a direction away from the first current collector to form a recessed structure, and the electrode assembly further includes: An adhesive layer is located within the recessed structure and connects the second region and the first current collector.

3. The battery cell according to claim 2, characterized in that, The adhesive layer is made of conductive adhesive.

4. The battery cell according to any one of claims 1-3, characterized in that, The second region is located on opposite sides of the first region and is connected to the opposite sides of the first region respectively.

5. The battery cell according to claim 4, characterized in that, The first region and the second region extend along a first direction, and along the first direction, the length of the second region is greater than or equal to the length of the first region.

6. The battery cell according to claim 5, wherein along the first direction, the length of the second region is greater than or equal to the length of the first active material layer.

7. The battery cell according to any one of claims 1-3, characterized in that, The first region includes a first side that is flush with one of the edges of the first active material layer, and the second region is disposed around the remaining sides of the first region other than the first side.

8. The battery cell according to claim 4 or 7, characterized in that, Along the relative directions of the second region located on opposite sides of the first region, the ratio of the length of the first region to the total length of the second region is greater than or equal to 0.5 and less than or equal to 2.

9. The battery cell according to any one of claims 1-8, characterized in that, The first current collector and the first active material layer located on the surface of the first current collector are wound together to form a first winding structure. The first electrode includes a first part and a second part adjacent to each other along the axial direction of the first winding structure. The first part and the second part are located in the first part, and the second part extends out of the first winding structure.

10. The battery cell according to claim 9, characterized in that, The second region is located at least on opposite sides of the first region, and the first region and the second region located on opposite sides of the first region extend along the axial direction of the first winding structure.

11. The battery cell according to claim 9 or 10, characterized in that, The first active material layer covering the surface of the first electrode tab away from the first current collector is referred to as the first sublayer. Along the winding direction of the first winding structure, the minimum distance between the surface of the first electrode tab away from the first current collector and the surface of the first sublayer away from the first current collector is equal.

12. The battery cell according to any one of claims 9-11, characterized in that, The minimum distance between each point on the surface of the first region and the second region away from the surface of the first current collector and the surface of the first current collector is equal.

13. The battery cell according to any one of claims 1-12, characterized in that, The maximum value of the total thickness of the first electrode tab and the first active material layer covering the surface of the first electrode tab is less than or equal to the minimum value of the thickness of the first active material layer covering the surface of the first current collector.

14. The battery cell according to claim 13, characterized in that, The ratio of the maximum thickness of the first electrode tab to the maximum thickness of the first active material layer is greater than or equal to 0.5 and less than 1.

15. The battery cell according to any one of claims 1-14, characterized in that, The first active material layer and the first tab are provided on both opposite surfaces of the first current collector.

16. The battery cell according to any one of claims 1-15, characterized in that, The first active material layer is a cathode active material layer.

17. The battery cell according to claim 16, characterized in that, The electrode assembly also includes: Second episode of fluid; An anode active material layer is located on a portion of the surface of the second current collector; The second tab is located at the beginning and / or end of the second current collector and at least one side of the anode active material layer.

18. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1-17.

19. An electrical appliance, characterized in that, Includes the battery device as described in claim 18.

20. An energy storage device, characterized in that, The energy storage device includes the battery device as described in claim 18, the battery device being used to store electrical energy.

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