Battery cell, battery device, and electric device

Abstract

The application discloses a battery monomer, a battery device and a power utilization device. The battery monomer comprises a shell and an electrode assembly, the electrode assembly comprises a laminated and rolled electrode tab assembly and a tab assembly connected thereto; along an unfolding direction, the electrode tab assembly comprises a starting section, a first coil, an intermediate coil and an ending section, the tab assembly is connected to the first coil and the intermediate coil; the unfolding length of the starting section and / or the ending section is shorter than half of the unfolding length of the first coil; viewed from the side of the tab assembly along the rolling axis direction, the size of the electrode assembly along a first direction is smaller than the size along a second direction, the first direction, the second direction and the rolling axis direction are perpendicular to each other, the starting end, the ending end and the tab assembly are located on the same side relative to the center line of the electrode assembly extending along the first direction, the same-polarity tab projections overlap each other along the first direction, and the different-polarity tab projections are spaced from each other. Thus, the uneven current distribution and lithium precipitation caused by the overlong starting section or ending section can be reduced.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to battery cells, battery devices, and power-consuming devices. Background Technology

[0002] The application of new energy batteries in daily life and industry is becoming increasingly widespread. For example, new energy vehicles equipped with batteries are already widely used, and battery devices are also increasingly being applied in energy storage. In new energy vehicles equipped with batteries, the battery device can provide all or part of the power. In the field of energy storage, battery devices can be installed in energy storage boxes or directly on the user side.

[0003] In related technologies, battery devices include individual battery cells, which can include electrode assemblies. Electrode assemblies can be stacked structures composed of multiple electrode sheets (also known as bare cells). Stacking and winding is a widely used electrode stacking method. Improving the uniformity of current density in stacked and wound electrode assemblies is one of the research topics in the industry. Utility Model Content

[0004] To address the aforementioned technical problems, embodiments of this application provide a battery cell, a battery device, and an electrical device that can improve the uniformity of current density.

[0005] The embodiments of this application are implemented through the following technical solutions.

[0006] A first aspect of this application provides a battery cell, which includes a casing and at least one electrode assembly. The electrode assembly includes a stacked and wound electrode assembly and a tab assembly connected to the electrode assembly. Along the unfolding direction of the stacked and wound electrode assembly, the electrode assembly includes a starting segment, a first loop, an intermediate loop, and a closing segment connected in sequence. Tab assemblies are connected to the first loop and the intermediate loop. At least one of the unfolding length of the starting segment and the unfolding length of the closing segment is shorter than half the unfolding length of the first loop. When the electrode assembly is viewed from the side where the tab assembly is located along the winding axis, the dimension of the electrode assembly along the first direction is smaller than the dimension along the second direction. The first direction and the second direction are perpendicular to each other and both perpendicular to the winding axis. Relative to the centerline of the electrode assembly extending along the first direction, the starting end of the starting segment, the closing end of the closing segment, and the tab assembly are located on the same side. When projected onto the same projection plane along the first direction, the projections of the same-type tabs in the tab assembly overlap each other, and the projections of the opposite-type tabs are spaced apart.

[0007] Since the starting end of the starting segment, the ending end of the ending segment, and the tab assembly are located on the same side relative to the centerline extending along the first direction of the electrode assembly, and at least one of the unfolded length of the starting segment and the unfolded length of the ending segment is shorter than half the unfolded length of the first loop, the length of the starting segment or the length of the ending segment can be kept within a suitable range, reducing the risk of uneven current density distribution and easy lithium plating due to excessive length of the starting segment or the ending segment; moreover, since the tab assembly is located on the same side relative to the centerline extending along the first direction of the electrode assembly, it is beneficial to centrally arrange and assemble electrode terminals, adapters, etc.

[0008] In some embodiments, the stacked and wound electrode assembly includes a straight portion and a bent portion, the bent portion being connected to both ends of the straight portion along a second direction, the tab assembly being located in the straight portion, and the end of the terminal section being located in the bent portion.

[0009] The tab assembly is located in the straight section, which helps maintain its flat state and reduces the likelihood of bending or deformation, thus lowering the risk of tab breakage. The end of the finishing section is located in the bend section, reducing the probability of warping at the end due to expansion stress.

[0010] In some embodiments, the electrode assembly includes a first electrode, a second electrode, and a spacer that are stacked and wound together. The first electrode and the second electrode have opposite polarities, and the spacer is used to isolate the first electrode and the second electrode. The tab assembly includes a plurality of first tabs and a plurality of second tabs. Each first tab is connected to a first electrode, and each second tab is connected to a second electrode. The first electrode includes a first starting segment, a first first loop, a first intermediate loop, and a first ending segment connected in sequence. The second electrode includes a second starting segment, a second first loop, a second intermediate loop, and a second ending segment connected in sequence. Two first tabs are provided in the first first loop, and one first tab is provided in each first intermediate loop. Two second tabs are provided in the second first loop, and one second tab is provided in each second intermediate loop. The first first loop is the first complete loop starting from the first first tab at the starting end of the starting segment closest to the first electrode. The second first loop is the first complete loop starting from the first second tab at the starting end of the starting segment closest to the second electrode.

[0011] Because the starting end of the first starting segment, the ending end of the first ending segment, and the first tab are located on the same side relative to the centerline extending along the first direction of the electrode assembly, and at least one of the unfolded length of the first starting segment and the unfolded length of the first ending segment is shorter than half the unfolded length of the first first loop, and the starting end of the second starting segment, the ending end of the second ending segment, and the second tab are located on the same side relative to the centerline extending along the first direction of the electrode assembly, and at least one of the unfolded length of the second starting segment and the unfolded length of the second ending segment is shorter than half the unfolded length of the second first loop. Therefore, the lengths of the starting segments or ending segments of the first and second electrodes can be kept within a suitable range, thereby reliably reducing the risk of uneven current density distribution and thus easy lithium plating due to excessively long starting or ending segments. Furthermore, when the unfolded lengths of each starting segment and each ending segment are shorter than half the unfolded length of their respective first loops, the lengths of each starting segment and each ending segment can be kept within a suitable range, thereby further reducing the risk of lithium plating due to uneven current density distribution.

[0012] In some embodiments, when the electrode assembly is viewed from the side where the tab assembly is located along the winding axis, the end of the first ending segment, the end of the second ending segment, a first tab located in the first first loop, a first tab located in each of the first intermediate loops, a second tab located in the second first loop, and a second tab located in each of the second intermediate loops are located in the same quadrant. Furthermore, the two first tabs located in the first first loop are located in quadrants adjacent to each other along the first direction, and the two second tabs located in the second first loop are located in quadrants adjacent to each other along the first direction. Here, the center line of the electrode assembly extending along the first direction intersects with the center line extending along the second direction to form four quadrants.

[0013] This allows for a further reduction in the lengths of the first and second termination segments, the first and second starting segments, and the second starting segment, thereby further reducing the risk of uneven current density distribution and lithium plating due to excessive length of the starting or termination segments.

[0014] In some embodiments, the tab assembly is connected to the same side of the electrode assembly along the winding axis.

[0015] This allows for centralized placement of the tab assembly, reducing the space required for tab connections (e.g., the space needed for adapters) and improving the internal space utilization of the battery cell. Furthermore, it simplifies the tab cutting process and equipment, saving factory space.

[0016] In some embodiments, the size of the electrode assembly along the second direction is in the range of 200 mm to 600 mm.

[0017] This allows for a balance between the capacity of individual battery cells and the uniformity of current distribution in the electrode assembly.

[0018] In some embodiments, the size of the electrode assembly along the first direction is in the range of 10 mm to 50 mm.

[0019] This allows for a balance between the capacity of individual battery cells and the uniformity of current distribution in the electrode assembly.

[0020] In some embodiments, the dimensions of the electrode assembly along the winding axis are in the range of 50 mm to 350 mm.

[0021] This allows for a balance between the capacity of individual battery cells and the uniformity of current distribution in the electrode assembly.

[0022] In some embodiments, the electrode assembly includes a first electrode, a second electrode, and an isolator that are stacked and wound together, the first electrode and the second electrode having opposite polarities, and the tab assembly including a plurality of first tabs and a plurality of second tabs, each first tab being connected to and extending from the first electrode, and each second tab being connected to and extending from the second electrode.

[0023] Because it has multiple first tabs and multiple second tabs, the first tabs and second tabs have opposite polarities, and the projections of the same-polarity tabs along the first direction have overlapping portions, multiple first tabs can be connected together (e.g., by welding), and multiple second tabs can be connected together (e.g., by welding), thereby enabling easy connection to electrode terminals or adapters.

[0024] In some embodiments, along the first direction, each first tab extends from the first electrode plate by the same length, and each second tab extends from the second electrode plate by the same length; or, along the first direction from one side to the other, the length of each first tab extending from the first electrode plate gradually increases, and the length of each second tab extending from the second electrode plate gradually increases.

[0025] Since the first tabs extend from the first electrode plate to the same length along the first direction, and the second tabs extend from the second electrode plate to the same length, this facilitates processing, improves the manufacturing efficiency of the electrode assembly, and consequently improves the manufacturing efficiency of the battery cell. Because the lengths of the first tabs and second tabs gradually increase from one side to the other along the first direction, after welding the first tabs together or the second tabs together, the tips of the first tabs or the tips of the second tabs can be at approximately the same height along the first direction. This makes the shape of the tab assembly more regular, which is beneficial for connecting the tab assembly to components (such as adapters or electrode terminals) that conduct or conduct current from the electrode assembly. Furthermore, the direction in which the tab extension length gradually increases along the first direction can be determined based on which side of the electrode assembly the tabs are desired to converge on, increasing the freedom in determining the extension lengths of the first and / or second tabs and enabling them to fit within the assembly space of the battery cell's casing.

[0026] In some embodiments, each first electrode tab is formed to extend from one side to the other along a first direction, and the width of each first electrode tab along a second direction is reduced. Each second electrode tab is formed to extend from one side to the other along a first direction, and the width of each second electrode tab along the second direction is reduced.

[0027] Therefore, when bending the first tab and / or the second tab, the probability or degree of misalignment between the first tab and / or the second tab can be reduced. Furthermore, the direction in which the tab extension width gradually increases along the first direction can be determined based on which side of the electrode assembly the tabs are desired to converge on, thereby increasing the freedom of the width of the first tab and / or the second tab in the second direction and enabling the tabs to fit into the assembly space within the casing of the battery cell.

[0028] In some embodiments, the battery cell further includes a first electrode terminal and a second electrode terminal. The first electrode terminal is disposed on the housing and connected to each first tab, and the second electrode terminal is disposed on the housing and connected to each second tab. Along the winding axis, relative to the electrode assembly, the first electrode terminal and the second electrode terminal are located on the same side as the first tab and the second tab.

[0029] Since the first electrode terminal is connected to the first tab and the second electrode terminal is connected to the second tab, the first and second electrode terminals can conduct or conduct current through the electrode assembly. Because the first and second electrode terminals are located on the same side as the first and second tabs, it not only facilitates the connection of the first and second electrode terminals to the first and second tabs respectively, but also reduces the connection paths between the first and second electrode terminals and the first and second tabs, lowering the resistance of the connection paths between the electrode terminals and the tab assembly. Furthermore, it allows for a compact arrangement of the first and second electrode terminals with the first and second tabs, improving the space utilization rate inside and on the surface of the battery cell.

[0030] In some embodiments, the first electrode terminal, the second electrode terminal, the first tab, and the second tab are located on the same side relative to the centerline of the electrode assembly extending in a first direction.

[0031] This allows the first and second electrode terminals to be more compactly arranged with the first and second tabs, further improving the space utilization rate inside and on the surface of the battery cell.

[0032] A second aspect of this application provides a battery device comprising at least one battery cell provided in the first aspect of this application.

[0033] Therefore, it can improve the uniformity of current density in the battery device.

[0034] A third aspect of this application provides an electrical device that includes at least one battery cell provided in the first aspect of this application, or includes at least one battery device provided in the second aspect of this application.

[0035] Therefore, it can improve the uniformity of current density in electrical devices. Attached Figure Description

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0037] Figure 1 Structural schematic diagrams of vehicles provided for some embodiments of this application;

[0038] Figure 2 Exploded perspective view of a battery device provided for some embodiments of this application;

[0039] Figure 3A three-dimensional structural schematic diagram of a battery cell provided for some embodiments of this application;

[0040] Figure 4 An exploded perspective view of a battery cell provided for some embodiments of this application;

[0041] Figure 5 A three-dimensional structural schematic diagram of an electrode assembly provided for some embodiments of this application;

[0042] Figure 6 A partial schematic diagram of the electrode assembly provided for some embodiments of this application;

[0043] Figure 7 Schematic diagrams of partial structures of electrode assemblies provided for other embodiments of this application;

[0044] Figure 8 A partial schematic diagram of the structure of an electrode assembly provided for some further embodiments of this application;

[0045] Figure 9 A schematic diagram showing a partial unfolded structure of an electrode assembly provided for some embodiments of this application;

[0046] Figure 10 Provided for some embodiments of this application Figure 5 A front view schematic diagram of the electrode assembly;

[0047] Figure 11 Provided for some embodiments of this application Figure 5 A top view of the electrode assembly;

[0048] Figure 12 Provided for some embodiments of this application Figure 5 A side view of the electrode assembly;

[0049] Figure 13 Line graphs showing the current variation distribution of the electrode assembly under normal conditions, provided for some embodiments of this application;

[0050] Figure 14 Line graphs showing the anode potential variation distribution of the electrode assembly under normal conditions, provided for some embodiments of this application;

[0051] Figure 15 Line graphs showing the current variation distribution of the electrode assembly under the structure of this application are provided for some embodiments of this application;

[0052] Figure 16 Line graphs showing the anode potential variation distribution of the electrode assembly under the structure of this application, provided for some embodiments of this application.

[0053] Explanation of reference numerals in the attached figures

[0054] 1000, Vehicle; 100, Battery Unit; 200, Controller; 300, Motor; 10, Battery Cell; 20, Housing; 20a, First Housing; 20b, Second Housing; 1, Shell; 2, Electrode Assembly; 21, First Electrode; 211, First Starting Section; 212, First First Coil; 213, First Intermediate Coil; 214, First Ending Section; 22, Second Electrode; 221, Second Starting Section; 222, Second First Coil; 223, Second Intermediate Coil; 224, Second Ending Section; 3, Tab Assembly; 31, First Tab; 32, Second Tab; 4, Electrode Terminal; 41, First Electrode Terminal; 42, Second Electrode Terminal; 5, Adapter; X, First Direction; Y, Second Direction; Z, Winding Axis Direction; C, Length Direction of Electrode Assembly. Detailed Implementation

[0055] 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.

[0056] 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 belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application; the terms “comprising” and “having”, and any variations thereof, in the specification and the foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0057] 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.

[0058] 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.

[0059] 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 are in an "or" relationship.

[0060] In the description of the embodiments of this application, the technical terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "circumferential", etc., 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 do not indicate or imply that the device or element referred to must have a specific orientation, be constructed, operated or used in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0061] 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. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0062] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical term "contact" should be interpreted broadly, and can be direct contact, contact through an intermediate medium layer, contact between two contacting parties with substantially no interaction force, or contact between two contacting parties with interaction force.

[0063] The following is a detailed description of this application.

[0064] In related technologies, battery devices include individual battery cells, which can include electrode assemblies. Electrode assemblies can be stacked structures composed of multiple electrode sheets (also known as bare cells). Stacking and winding is a widely used electrode stacking method. Improving the uniformity of current density in stacked and wound electrode assemblies is one of the research topics in the industry.

[0065] Research has revealed that the arrangement of the tabs within the electrode assembly significantly impacts current distribution during charging and / or discharging. Further simulations showed that when the initial or final section of the electrode assembly has a long unfolded length (or a "first cut" or "last cut," sometimes referring to the distance between the starting point and the centerline of the first tab, and the distance between the centerline of the last tab and the ending point), uneven current density distribution occurs. Further analysis indicates that if the first or last cut is longer than half the distance between the centerlines of the first and second tabs, uneven current density is more likely to occur. Therefore, shortening the unfolded length of the initial and / or final sections is considered, ensuring the length of either section is within a suitable range to reduce the risk of uneven current density distribution and subsequent lithium plating due to excessive length. Additionally, it is desirable to position the tabs slightly off-center along the length of the electrode assembly to facilitate tab convergence and welding.

[0066] Based on this design concept, this application provides a battery cell, which includes a casing and at least one electrode assembly. The electrode assembly includes stacked and wound electrode assemblies and tab assemblies connected to the electrode assemblies. Along the unfolding direction of the stacked and wound electrode assemblies, the electrode assembly includes a starting segment, a first loop, an intermediate loop, and a closing segment connected in sequence. Tab assemblies are connected to the first loop and the intermediate loop. At least one of the unfolding length of the starting segment and the unfolding length of the closing segment is shorter than half the unfolding length of the first loop. When the electrode assembly is viewed from the side where the tab assembly is located along the winding axis, the dimension of the electrode assembly along the first direction is smaller than the dimension along the second direction. The first direction and the second direction are perpendicular to each other and both are perpendicular to the winding axis. Relative to the centerline of the electrode assembly extending along the first direction, the starting end of the starting segment, the closing end of the closing segment, and the tab assembly are located on the same side. When projected onto the same projection plane along the first direction, the projections of the same-type tabs in the tab assembly overlap each other, and the projections of the opposite-type tabs are spaced apart.

[0067] Since the starting end of the starting segment, the ending end of the ending segment, and the tab assembly are located on the same side relative to the centerline extending along the first direction of the electrode assembly, and at least one of the unfolded length of the starting segment and the unfolded length of the ending segment is shorter than half the unfolded length of the first loop, the length of the starting segment or the length of the ending segment can be kept within a suitable range, reducing the risk of uneven current density distribution and easy lithium plating due to excessive length of the starting segment or the ending segment; moreover, since the tab assembly is located on the same side relative to the centerline extending along the first direction of the electrode assembly, it is beneficial to centrally arrange and assemble electrode terminals, adapters, etc.

[0068] The battery cells and battery devices provided in this application embodiment can be used, but are not limited to, in electrical devices such as energy storage devices, vehicles, ships, or aircraft.

[0069] This application also provides an electrical device including the above-described battery device. The electrical device can be, but is not limited to, a mobile phone, tablet, laptop, electric toy, power tool, electric vehicle, electric car, ship, 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.

[0070] In the following embodiments, for ease of explanation, an example of an electrical device of this application, namely a vehicle 1000, will be used for illustration.

[0071] Figure 1 The diagram illustrates the structure of a vehicle 1000 as 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. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Figure 1 As shown, a battery device 100 is installed inside the vehicle 1000. The battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 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 device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during starting, navigation, and driving.

[0072] In some embodiments of this application, the battery device 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.

[0073] Figure 2 This is an exploded perspective view of a battery device 100 provided for some embodiments of this application; 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 10, which are connected in series, parallel, or mixed connections via busbars.

[0074] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells 10; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells 10 into a single module. As an example, a battery module can be formed by bundling multiple battery cells 10 together with cable ties.

[0075] In some embodiments, the battery device 100 may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0076] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0077] As an example, the battery cell assembly can also be housed in the housing by directly fixing multiple battery cells 10 to the housing 20.

[0078] As an example, the housing 20 may include a first housing 20a and a second housing 20b. The first housing 20a and the second housing 20b are fastened together to form a closed space inside the housing 20 to house the battery cell 10 assembly. Here, "closed" refers to covering or closing, which can be sealed or unsealed. The first housing 20a may be a top cover or a bottom plate.

[0079] In this embodiment of the application, the battery cell 10 can be a secondary battery, which refers to a battery cell that can be used again after being discharged by recharging to activate the active materials.

[0080] The battery cell 10 can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0081] Below, refer to Figures 3 to 16 Some embodiments of this application will be described in detail.

[0082] In the description of the embodiments of this disclosure, for ease of explanation, the direction of arrow X represents the "first direction", the direction of arrow Y represents the "second direction", the direction of arrow Z represents the "winding axis direction", and the direction of arrow C represents the "length direction of the electrode assembly". The first direction, the second direction, and the winding axis direction intersect each other. Furthermore, the first direction, the second direction, and the winding axis direction are perpendicular to each other.

[0083] The first aspect of this application provides a battery cell, such as Figure 3 and Figure 12 As shown, the battery cell includes a casing 1 and at least one electrode assembly 2. The electrode assembly 2 includes stacked and wound electrode assemblies and tab assemblies 3 connected to the electrode assemblies. Along the unfolding direction of the stacked and wound electrode assemblies, the electrode assembly includes a starting segment, a first loop, an intermediate loop, and a closing segment connected in sequence. Tab assemblies 3 are connected to the first loop and the intermediate loop. At least one of the unfolding length of the starting segment and the unfolding length of the closing segment is shorter than half the unfolding length of the first loop. When the electrode assembly 2 is viewed from the side where the tab assembly 3 is located along the winding axis direction Z, the size of the electrode assembly 2 along the first direction X is smaller than the size along the second direction Y. The first direction X and the second direction Y are perpendicular to each other and both are perpendicular to the winding axis direction Z. Relative to the center line L3 extending along the first direction X of the electrode assembly 2, the starting end of the starting segment, the closing end of the closing segment, and the tab assembly 3 are located on the same side. When projected onto the same projection plane along the first direction X, the projections of the same-type tabs in the tab assembly 3 overlap each other, and the projections of the opposite-type tabs are spaced apart.

[0084] In some embodiments, such as Figure 4 As shown, a battery cell typically includes an electrode assembly 2 (see...). Figure 3 ).For example Figures 5 to 12 As shown, electrode assembly 2 includes stacked and wound electrode assemblies, such as... Figures 6 to 9 As shown, the stacked and wound electrode assembly includes a positive electrode, a negative electrode, and a separator (not shown in the diagram). Figures 6 to 9 (As shown in the diagram). During the charging and discharging process of a single battery cell, active ions repeatedly insert and extract between the positive and negative electrodes. A separator is placed between the positive and negative electrodes to prevent short circuits while allowing active ions to pass through. For example, the active ions can be lithium ions.

[0085] In some embodiments, the electrode assembly includes a first electrode 21 and a second electrode 22, wherein the first electrode 21 can be one of a positive electrode and a negative electrode, and the second electrode 22 can be the other of a positive electrode and a negative electrode.

[0086] In some embodiments, the positive electrode can be a positive electrode sheet, which may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0087] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0088] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, silver-treated aluminum or stainless steel, copper, aluminum, nickel, titanium, etc., can be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material on a polymer material substrate.

[0089] For example, the metallic material can be aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.

[0090] For example, the polymer material substrate can be a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.

[0091] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, the embodiments of this application are not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0092] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0093] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0094] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, copper, aluminum, nickel, titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. Composite current collectors can be formed by forming a metal material on a polymer material substrate. In some embodiments, the positive electrode current collector can be made of aluminum, and the negative electrode current collector can be made of copper.

[0095] For example, the metallic material can be copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.

[0096] For example, the polymer material substrate can be a substrate such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.

[0097] In some embodiments, the electrode assembly 2 further includes an isolator disposed between the positive and negative electrodes.

[0098] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0099] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride, and ceramic.

[0100] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0101] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0102] In some embodiments, the electrode assembly 2 is a wound structure. The positive and negative electrodes are wound into a wound structure.

[0103] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by winding.

[0104] In some embodiments, the electrode assembly 2 may be flat or polygonal, etc.

[0105] In some embodiments, the electrode assembly 2 includes a tab assembly 3 connected to the electrode assembly, the electrode assembly and the tab assembly 3 being electrically connected, and the tab assembly 3 being able to draw current from the electrode assembly 2.

[0106] In some embodiments, the electrode assembly 3 includes a first electrode 31 and a second electrode 32.

[0107] In some embodiments, the first electrode 31 is one of the positive electrode and the negative electrode, and the second electrode 32 is the other of the positive electrode and the negative electrode.

[0108] In some embodiments, such as Figure 3 and Figure 4As shown, a single battery cell may include a casing 1. The casing 1 encapsulates the electrode assembly 2 and electrolyte components, etc. The casing 1 can be a steel casing, aluminum casing, plastic casing, composite metal casing, or aluminum-plastic film, etc.

[0109] As an example, the battery cell can be a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells and polyprismatic battery cells, such as hexagonal prismatic battery cells. There are no particular limitations in the embodiments of this application. In the following embodiments, a prismatic battery cell is used as an example for illustration.

[0110] In some embodiments, such as Figure 3 and Figure 4 As shown, the outer casing 1 includes an end cap assembly and a housing. The housing has an opening, and the end cap assembly closes the opening to form a sealed space for accommodating the electrode assembly 2 and substances such as electrolytes. The housing may have one or more openings. The end cap assembly may also have one or more.

[0111] In some embodiments, at least one electrode terminal 4 is provided on the housing 1, and the electrode terminal 4 is electrically connected to the tab assembly 3. The electrode terminal 4 can be directly connected to the tab assembly 3, or it can be indirectly connected to the tab assembly 3 through an adapter. The electrode terminal 4 can be provided on the end cap assembly, or it can be provided on the housing.

[0112] In some embodiments, such as Figures 6 to 8 As shown, the electrode assembly includes a starting section, a first loop, an intermediate loop, and a closing section connected in sequence. A tab assembly 3 is connected to both the first loop and the intermediate loop. When the electrode assembly is unfolded, the section from the starting end (the end of the innermost electrode assembly) to the closing end (the end of the outermost electrode assembly) is the starting section. The section that winds around the electrode assembly for one loop (360°) from the end of the starting section, which is also the end of the first tab assembly 3 (near the starting end), is the first loop. The section that winds around the electrode assembly for one loop (360°) starting from the end of the first loop is the intermediate loop. The section from the end of the last intermediate loop to the closing end (the end of the outermost electrode assembly) is the closing section.

[0113] When an electrode assembly includes multiple electrodes, the starting segment, first loop, middle loop, and ending segment refer to each individual electrode; that is, each electrode has its own starting segment, first loop, middle loop, and ending segment.

[0114] In some specific embodiments, such as Figure 6 and Figure 7As shown, the first ring of an electrode (first electrode 21 or second electrode 22) is provided with two electrode tabs (two first electrode tabs 31 or two second electrode tabs 32), and each middle ring is provided with one electrode tab (one first electrode tab 31 or one second electrode tab 32).

[0115] In other specific embodiments, such as Figure 8 As shown, an electrode (a first electrode 31 or a second electrode 32) is provided with an electrode tab (a first electrode 31 or a second electrode 32) in the first ring, an electrode tab (a first electrode 31 or a second electrode 32) is provided in the last ring, and an electrode tab (a first electrode 31 or a second electrode 32) is provided in each middle ring.

[0116] In some embodiments, the stacked and wound electrode assembly 2 includes a straight portion and a bent portion, the bent portion being connected to both ends of the straight portion along the second direction Y.

[0117] like Figure 6 As shown, the portion of electrode assembly 2 located in dashed frame O1 is a straight portion, while the portion of electrode assembly 2 located in dashed frame O2 is a bent portion.

[0118] In some embodiments, the dimension of the electrode assembly 2 along the first direction X refers to the maximum dimension of the electrode assembly 2 from one end face to the other end face along the first direction X. For example... Figure 6 One end face of the straight portion along the first direction X (e.g.) Figure 6 The upper surface shown) to the other end face (e.g. Figure 6 The dimensions of the lower surface shown.

[0119] In some embodiments, such as Figure 6 As shown, the dimension of electrode assembly 2 along the first direction X refers to the thickness dimension of electrode assembly 2.

[0120] In some embodiments, the dimension of the electrode assembly 2 along the second direction Y refers to the maximum dimension of the electrode assembly 2 from one end face to the other end face along the second direction Y. For example, Figure 6 The dimension from the leftmost end face of the left bend to the rightmost end face of the right bend in the indicated orientation.

[0121] In some embodiments, such as Figure 6 As shown, the dimension of electrode assembly 2 along the second direction Y refers to the length dimension of electrode assembly 2.

[0122] In some embodiments, the thickness of the electrode assembly 2 is smaller than the length of the electrode assembly 2.

[0123] In some embodiments, such as Figures 6 to 8As shown, the starting end of the starting segment, the ending end of the ending segment, and the tab assembly 3 are located on the same side of the centerline L3 extending along the first direction X of the electrode assembly 2 (e.g., Figure 6 (As shown on the left or right side). The centerline L3 extending along the first direction X is the centerline of the length of the electrode assembly 2.

[0124] In some embodiments, when projected onto the same projection plane along the first direction X, the projections of the same-type electrodes in the electrode assembly 3 overlap with each other, and the projections of the opposite-type electrodes are spaced apart from each other.

[0125] In some embodiments, when projected onto the same projection plane along the first direction X, the projections of the first tabs 31 in the tab assembly 3 overlap with each other, and may partially or completely overlap; when projected onto the same projection plane along the first direction X, the projections of the second tabs 32 in the tab assembly 3 overlap with each other, and may partially or completely overlap.

[0126] In some embodiments, the projections along the first direction X onto the same projection plane are spaced apart from the projections of the first electrode 31 and the second electrode 32 in the electrode assembly 3.

[0127] Since the starting end of the starting segment, the ending end of the ending segment, and the tab assembly 3 are located on the same side relative to the centerline extending along the first direction X of the electrode assembly 2, and at least one of the unfolded length of the starting segment and the unfolded length of the ending segment is shorter than half the unfolded length of the first loop, the length of the starting segment or the length of the ending segment can be kept within a suitable range. Simulation analysis has shown that keeping the length of the starting segment or the ending segment within a suitable range reduces the risk of uneven current density distribution and thus lithium plating due to excessive length of the starting segment or the ending segment. Specifically, during the charging or discharging process of a battery cell, when the negative electrode potential (vs. Li) is within a suitable range, the starting end of the starting segment, the ending end of the ending segment, and the tab assembly 3 are located on the same side, and at least one of the unfolded lengths of the starting segment and the ending segment is shorter than half the unfolded length of the first loop, the length of the starting segment or the ending segment can be kept within a suitable range. + When ( / Li)≤0V, thermodynamically, lithium ions tend to deposit as metallic lithium on the negative electrode surface. Specifically, lithium ions no longer embed in the graphite layer but are deposited on the surface as metallic lithium. Lithium deposition consumes active lithium, increases internal resistance, and can even cause short circuits and thermal runaway. Since the center line of the tab assembly 3 and the electrode assembly 2 extending along the first direction X are on the same side, it is beneficial for the centralized arrangement and assembly of the electrode terminals 4, adapters, etc.

[0128] In some embodiments, the stacked and wound electrode assembly 2 includes a straight portion and a bent portion, the bent portion being connected to both ends of the straight portion along the second direction Y, the tab assembly 3 being located in the straight portion, and the end of the terminal section being located in the bent portion.

[0129] The straight section has good structural rigidity, and fixing the tab in this area can reduce displacement or deformation caused by volume changes during the charging and discharging of the battery cell (such as the expansion of the electrode assembly 2 caused by lithium ion insertion / extraction), thus reducing the risk of tab breakage. The end of the tail section is located at the bend, which reduces the probability of the tail section warping due to expansion stress.

[0130] In some embodiments, such as Figure 6 and Figure 7 As shown, electrode assembly 2 includes a first electrode 21, a second electrode 22, and a separator, all layered and wound. The first electrode 21 and the second electrode 22 have opposite polarities, and the separator is used to isolate the first electrode 21 and the second electrode 22. Electrode assembly 3 includes multiple first electrodes 31 and multiple second electrodes 32. Each first electrode 31 is connected to the first electrode 21, and each second electrode 32 is connected to the second electrode 22. The first electrode 21 includes a first starting segment 211, a first first coil 212, a first intermediate coil 213, and a first ending segment 214 connected in sequence. The second electrode 22 includes a second starting segment 214 connected in sequence. 21. Second first loop 222, second intermediate loop 223, and second closing segment 224; The first first loop 212 is provided with two first pole tabs 31, and each first intermediate loop 213 is provided with one first pole tab 31. The second first loop 222 is provided with two second pole tabs 32, and each second intermediate loop 223 is provided with one second pole tab 32. The first first loop 212 is the first complete loop starting from the first first pole tab 31 at the beginning of the segment closest to the first pole piece 21. The second first loop 222 is the first complete loop starting from the first second pole tab 32 at the beginning of the segment closest to the second pole piece 22.

[0131] In some embodiments, such as Figure 6 As shown, in the first electrode 21, along the direction from the first starting end (the end of the innermost first electrode 21) to the first ending end (the end of the outermost first electrode 21), the first electrode segment between the dotted line L1 at the first first electrode tab 31 and the first starting end is the first starting segment 211. The first complete loop starting from the first first electrode tab 31 closest to the starting end is the first first loop 212. Each subsequent complete loop is a first intermediate loop 213, that is, one loop from the dotted line L1 back to the dotted line L1 constitutes one complete loop. The last segment that is less than one complete loop is the first ending segment 214. For example, Figure 6 As shown, along the direction from the first ending end to the first starting end, the first pole segment between the first ending end and the dashed line L1 is the first ending segment 214.

[0132] In some embodiments, such as Figures 6 to 7As shown, the first ring 212 has two first tabs 31. One first tab 31 is located in the portion of the first ring 212 closest to the first starting segment 211, and one first tab 31 is located on one side of the center line L4 extending along the second direction Y of the electrode assembly 2, while the other first tab 31 is located on the other side of the center line L4 extending along the second direction Y of the electrode assembly 2. The first tab 31 in the first intermediate ring 213 and the other first tab 31 in the first ring 212 are located on the same side of the center line L4 extending along the second direction Y of the electrode assembly 2. The center line L4 extending along the second direction Y is the center line of the thickness of the electrode assembly 2.

[0133] In some embodiments, such as Figure 6 As shown, in the second electrode 22, along the direction from the second starting end (the end of the innermost second electrode 22) to the second ending end (the end of the outermost second electrode 22), the second electrode segment between the dotted line L1 at the first second electrode tab 32 and the second starting end is the second starting segment 221. The first complete loop starting from the first second electrode tab 32 closest to the starting end is the second first loop 222. Each subsequent complete loop is a second intermediate loop 223, that is, one loop from the dotted line L2 back to the dotted line L2 constitutes one complete loop. The last segment that is less than one complete loop is the second ending segment 224. For example, Figure 6 As shown, along the direction from the second ending end to the second starting end, the second pole segment between the second ending end and the dashed line L1 is the second ending segment 224.

[0134] In some embodiments, such as Figures 6 to 7 As shown, the second first ring 222 is provided with two second electrode tabs 32. One of the second electrode tabs 32 is located in the part of the second first ring 222 closest to the second starting segment 221. One of the second electrode tabs 32 is located on one side of the center line L4 extending along the second direction Y of the electrode assembly 2, and the other second electrode tab 32 is located on the other side of the center line L4 extending along the second direction Y of the electrode assembly 2. The second electrode tab 32 provided in the second intermediate ring 223 and the other second electrode tab 32 provided in the second first ring 222 are located on the same side of the center line L4 extending along the second direction Y of the electrode assembly 2.

[0135] Because the starting end of the first starting segment 211, the ending end of the first ending segment 214, and the first tab 31 are located on the same side relative to the centerline extending along the first direction X of the electrode assembly 2, and at least one of the unfolded lengths of the first starting segment 211 and the first ending segment 214 is shorter than half the unfolded length of the first first loop 212, and the starting end of the second starting segment 221, the ending end of the second ending segment 224, and the second tab 32 are located on the same side relative to the centerline extending along the first direction X of the electrode assembly 2, and at least one of the unfolded lengths of the second starting segment 221 and the second ending segment 224 is shorter than half the unfolded length of the second first loop 222, the lengths of the starting or ending segments of the first electrode 21 and the second electrode 22 are within a suitable range, further reducing the risk of uneven current density distribution and easy lithium plating due to excessively long starting or ending segments.

[0136] In some embodiments, when viewing the electrode assembly 2 from the side where the tab assembly 3 is located along the winding axis direction Z, the end of the first end section 214, the end of the second end section 224, a first tab 31 located in the first first loop 212, a first tab 31 located in each of the first intermediate loops 213, a second tab 32 located in the second first loop 222, and a second tab 32 located in each of the second intermediate loops 223 are located in the same quadrant. Furthermore, the two first tabs 31 located in the first first loop 212 are respectively located in quadrants adjacent to each other along the first direction X, and the two second tabs 32 located in the second first loop 222 are respectively located in quadrants adjacent to each other along the first direction X. Here, the center line L3 extending along the first direction X of the electrode assembly 2 intersects with the center line L4 extending along the second direction Y to form four quadrants.

[0137] like Figure 6 and Figure 7 As shown, the end point, the other tab in the first loop, and the tabs in each middle loop are located in the same quadrant (e.g., Figure 6 The second quadrant shown), one of the poles in the first ring is located in the quadrant adjacent to the first direction X (e.g., the second quadrant shown). Figure 6 (as shown in the third quadrant).

[0138] This allows the lengths of the first termination segment 214, the second termination segment 224, the first starting segment 211, and the second starting segment 221 to be within a suitable range, further reducing the risk of uneven current density distribution and easy lithium plating due to excessive length of the starting segment or termination segment.

[0139] In some embodiments, such as Figures 5 to 8 , Figures 10 to 12 As shown, the tab assembly 3 is connected to the same side of the electrode assembly along the winding axis direction Z (e.g., Figure 11 (See the bottom side).

[0140] This allows the tab assembly 3 to be centrally located, improving the space utilization rate inside the battery cell.

[0141] It is understandable that, such as Figure 9 As shown, the tab assembly 3 is connected to both sides of the electrode assembly along the Z-axis (e.g., Figure 9 (See upper and lower sides). For example, the first tabs 31 are all located on one side of the electrode assembly along the winding axis direction Z (e.g., the upper and lower sides). Figure 9 As shown on the upper side), the second tabs 32 are all located on the other side of the electrode assembly along the winding axis direction Z (e.g., the upper side). Figure 9 (See the bottom side).

[0142] In some embodiments, such as Figure 10 As shown, the dimension L5 of the electrode assembly 2 along the second direction Y is in the range of 200mm to 600mm.

[0143] Optionally, the dimension L5 of the electrode assembly 2 along the second direction Y can be 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, 550mm or 600mm, etc., or other values ​​within the above range.

[0144] This allows for a balance between the capacity of individual battery cells and the uniformity of current distribution in electrode assembly 2.

[0145] In some embodiments, such as Figure 10 As shown, the dimension L6 of the electrode assembly 2 along the first direction X is in the range of 10mm to 50mm.

[0146] Optionally, the dimension L6 of the electrode assembly 2 along the first direction X can be 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm or 50mm, etc., or other values ​​within the above range.

[0147] This allows for a balance between the capacity of individual battery cells and the uniformity of current distribution in electrode assembly 2.

[0148] In some embodiments, such as Figure 11 As shown, the dimension L7 of electrode assembly 2 along the winding axis direction Z is in the range of 50mm to 350mm. The dimension L7 of electrode assembly 2 along the winding axis direction Z refers to the dimension L7 of one end face of electrode assembly 2 (specifically, electrode assembly) along the winding axis direction Z (e.g., ...). Figure 11 From the upper end face shown to the other end face (e.g.) Figure 11The maximum dimension between the lower end faces shown, and the dimension L7 of electrode assembly 2 along the winding axis direction Z does not include the dimension of the tab.

[0149] Optionally, the dimension of the electrode assembly 2 along the winding axis direction Z is 50mm, 60mm, 75mm, 100mm, 110mm, 130mm, 150mm, 170mm, 190mm or 200mm, 220mm, 250mm, 300mm, 330mm, 350mm, etc., and of course, it can also be other values ​​within the above range.

[0150] This allows for a balance between the capacity of individual battery cells and the uniformity of current distribution in electrode assembly 2.

[0151] In some embodiments, such as Figures 6 to 8 As shown, the electrode assembly 2 includes a first electrode 21, a second electrode 22, and a spacer (not shown in the diagram). Figures 6 to 8 (as shown in the diagram), the first electrode 21 and the second electrode 22 have opposite polarities. The electrode assembly 3 includes a plurality of first electrodes 31 and a plurality of second electrodes 32. Each first electrode 31 is connected to the first electrode 21 and extends out of the first electrode 21, and each second electrode 32 is connected to the second electrode 22 and extends out of the second electrode 22.

[0152] In some embodiments, the first electrode 21 and the second electrode 22 have opposite polarities, with one of the first electrode 21 and the second electrode 22 being the positive electrode and the other being the negative electrode.

[0153] In one specific embodiment, the first electrode 21 is the negative electrode and the second electrode 22 is the positive electrode, with the first electrode 21 having at least one more turn than the second electrode 22.

[0154] In one specific embodiment, when the electrode assembly 2 is in the unfolded state, the two ends of the first electrode 21 along the length direction C of the electrode assembly extend beyond the two ends of the second electrode 22 along the length direction C of the electrode assembly.

[0155] In one specific embodiment, the first electrode 21 is the negative electrode, and the outermost layer of the electrode assembly 2 is the electrode of the first electrode 21.

[0156] In one specific embodiment, the first electrode 21 is the negative electrode, and the innermost layer of the electrode assembly 2 is the electrode of the first electrode 21.

[0157] Since the first electrode 21 and the second electrode 22 have opposite polarities, they can form a closed circuit to enable the charging and discharging of the electrode assembly 2.

[0158] In some embodiments, such as Figure 12As shown, along the first direction X, the lengths of each first electrode tab 31 extending from the first electrode plate 21 are the same, and the lengths of each second electrode tab 32 extending from the second electrode plate 22 are the same; or, along the first direction X from one side to the other, the lengths of each first electrode tab 31 extending from the first electrode plate 21 gradually increase, and the lengths of each second electrode tab 32 extending from the second electrode plate 22 gradually increase.

[0159] The length of each first electrode tab 31 extending from the first electrode plate 21 refers to the projection along a direction perpendicular to the direction in which the first electrode tab 31 extends from the first electrode plate 21. The portion of the projection of the first electrode tab 31 that does not overlap with the first electrode plate 21 extends along both ends of the direction in which the first electrode tab 31 extends from the first electrode plate 21 (e.g., Figure 12 The distance between the left and right ends shown.

[0160] The length of each second electrode tab 32 extending from the second electrode plate 22 refers to the projection along a direction perpendicular to the direction in which the second electrode tab 32 extends from the second electrode plate 22. The portion of the projection of the second electrode tab 32 that does not overlap with the second electrode plate 22 extends along both ends of the direction in which the second electrode tab 32 extends from the second electrode plate 22 (e.g., Figure 12 The distance between the left and right ends shown.

[0161] In some embodiments, such as Figure 12 As shown, along the direction in which the first electrode tab 31 extends from the first electrode plate 21, the length L8 of each first electrode tab 31 extending from the first electrode plate 21 is the same.

[0162] Since the lengths of the first tabs 31 extending from the first electrode plate 21 are the same along the first direction X, and the lengths of the second tabs 32 extending from the second electrode plate 22 are the same, it is convenient to process and improves the manufacturing efficiency of the electrode assembly 2, thereby improving the manufacturing efficiency of the battery cell.

[0163] In some embodiments, the first direction X is from one side toward the other (e.g.) Figure 12 As shown from the bottom to the top, or Figure 12 (As shown from the upper side to the lower side), the length L8 of each first electrode tab 31 extending from the first electrode plate 21 gradually increases.

[0164] As the length of each first tab 31 extending from the first electrode plate 21 gradually increases along the first direction X from one side to the other, and the length of each second tab 32 extending from the second electrode plate 22 gradually increases, after welding the first tabs 31 together or the second tabs 32 together, the first tabs 31 or the second tabs 32 can be located at approximately the same height along the first direction X, making the shape of the tab assembly 3 more regular, which is beneficial to the connection between the tab assembly 3 and the components (such as the adapter 5 or the electrode terminal 4) that conduct or conduct current from the electrode assembly 2.

[0165] For example, in Figure 12 In the illustrated embodiment, along the first direction X from the upper side to the lower side of the figure, the length of each first tab 31 extending from the first electrode plate 21 gradually increases. When the first tabs 31 are brought together, the tabs near the middle of the electrode assembly 2 along the first direction X are brought together towards the outermost first tab 31 along the first direction X. In this way, the ends of the cluster of first tabs in the gathered state are roughly flush. Of course, the reverse is also possible.

[0166] This increases the freedom of the extension length of the first tab 31 and / or the second tab 32, enabling the first tab 31 and / or the second tab 32 to fit into the assembly space within the casing 1 of the battery cell.

[0167] In some embodiments, each first electrode tab 31 is formed to face from one side to the other along a first direction X, and the width of each first electrode tab 31 along a second direction Y is reduced; each second electrode tab 32 is formed to face from one side to the other along a first direction X, and the width of each second electrode tab 32 along a second direction Y is reduced.

[0168] For example Figure 11 As shown, the width of the first electrode 31 along the second direction Y refers to the two end faces of the first electrode 31 along the second direction Y (e.g., Figure 11 The maximum distance between the left and right end faces shown; the width of the second pole tab 32 along the second direction Y refers to the two end faces of the second pole tab 32 along the second direction Y (e.g., the maximum distance between the left and right end faces shown); Figure 11 The maximum distance between the left and right end faces shown.

[0169] Therefore, when the first tab 31 and / or the second tab 32 are bent, the probability or degree of misalignment between the first tabs 31 and / or between the second tabs 32 can be reduced. Furthermore, the degree of freedom in the width of the first tab 31 and / or the second tab 32 in the second direction Y can be increased, allowing the tabs to fit into the assembly space within the casing 1 of the battery cell.

[0170] In some embodiments, such as Figure 4 As shown, the battery cell also includes a first electrode terminal 41 and a second electrode terminal 42. The first electrode terminal 41 is disposed on the housing 1 and connected to each first tab 31, and the second electrode terminal 42 is disposed on the housing 1 and connected to each second tab 32. Along the winding axis direction Z, relative to the electrode assembly 2, the first electrode terminal 41 and the second electrode terminal 42 are located on the same side as the first tab 31 and the second tab 32 (e.g., along the winding axis direction Z). Figure 4 (as shown on the upper side).

[0171] In some embodiments, the first electrode terminal 41 is electrically connected to all the first tabs 31. Optionally, the first electrode terminal 41 and each of the first tabs 31 may be directly or indirectly electrically connected, for example, the first electrode terminal 41 and each of the first tabs 31 may be electrically connected via an adapter 5.

[0172] In some embodiments, the second electrode terminal 42 is electrically connected to all the second tabs 32. Optionally, the second electrode terminal 42 and each of the second tabs 32 may be directly or indirectly electrically connected, for example, the second electrode terminal 42 and each of the second tabs 32 may be electrically connected via an adapter 5.

[0173] In some embodiments, the first electrode terminal 41 and the second electrode terminal 42 are disposed on the end cap assembly.

[0174] Since the first electrode terminal 41 is connected to the first tab 31 and the second electrode terminal 42 is connected to the second tab 32, the first electrode terminal 41 and the second electrode terminal 42 can conduct or conduct current into the electrode assembly 2. Because the first electrode terminal 41 and the second electrode terminal 42 are located on the same side as the first tab 31 and the second tab 32, it not only facilitates the connection of the first electrode terminal 41 and the second electrode terminal 42 to the first tab 31 and the second tab 32 respectively, but also reduces the connection path between the first electrode terminal 41 and the first tab 31 and the second electrode terminal 42 and the second tab 32, lowering the resistance of the connection path between the electrode terminal 4 and the tab assembly 3. Furthermore, it facilitates a compact arrangement of the first electrode terminal 41 and the second electrode terminal 42 with the first tab 31 and the second tab 32, improving the space utilization rate inside and on the surface of the battery cell.

[0175] In some embodiments, such as Figures 4 to 8 As shown, relative to the centerline L3 extending along the first direction X of the electrode assembly 2, the first electrode terminal 41, the second electrode terminal 42, the first tab 31, and the second tab 32 are located on the same side (e.g., relative to the centerline L3 extending along the first direction X of the electrode assembly 2). Figure 6 (As shown on the left).

[0176] This allows the first electrode terminal 41 and the second electrode terminal 42 to be more compactly arranged with the first tab 31 and the second tab 32, thereby further improving the space utilization rate inside and on the surface of the battery cell.

[0177] A second aspect of this application provides a battery device comprising at least one battery cell provided in the first aspect of this application.

[0178] Therefore, it can improve the uniformity of current density in the battery device.

[0179] A third aspect of this application provides an electrical device that includes at least one battery cell provided in the first aspect of this application, or includes at least one battery device provided in the second aspect of this application.

[0180] Therefore, it can improve the uniformity of current density in electrical devices.

[0181] In a specific embodiment, such as Figure 6 As shown, the first electrode 31 and the second electrode 32 are located on the same side of the center line L3 extending along the first direction X of the electrode assembly 2. The first terminal section 214 ends at the corner located in the second quadrant, and the second terminal section 224 ends at the corner located in the second quadrant. The first electrode 31 and the second electrode 32 are located in the second quadrant.

[0182] In one specific embodiment, the first electrode 21 is a negative electrode, and the second electrode 22 is a positive electrode. The positive electrode has M layers, and the negative electrode has N layers, where N = M + 2, where M and N are both positive integers. The first ring 212 has two first tabs 31, and each of the first intermediate rings 213 has one first tab 31. The number of first tabs 31 (negative tabs) is N / 2 + 1, and the number of second tabs 32 (positive tabs) is M / 2 + 1. Specifically, the innermost layer of the first electrode 21 has one first tab 31, and the innermost layer of the second electrode 22 has one... A second electrode tab 32 is located on the same side of the center line L3 extending along the first direction X, in the innermost layer of the first electrode plate 21, and on both sides of the center line L4 extending along the second direction Y, in the innermost layer of the first electrode plate 21, and on the same side of the center line L3 extending along the first direction X, in the innermost layer of the second electrode plate 22, and on both sides of the center line L4 extending along the second direction Y, in the innermost layer of the second electrode plate 22.

[0183] In previous reference examples, when the first tab 31 and the second tab 32 are located on the same side of the center line L3 extending along the first direction X and the center line L4 extending along the second direction Y of the electrode assembly 2, and the size of the electrode assembly 2 is relatively large, and the winding method of the electrode assembly 2 is such that one first tab 31 and one second tab 32 are produced in each turn, if the positional relationship of the tab assembly 3 in the electrode assembly 2 is not limited, during the winding process of the electrode assembly 2, there is usually a situation where the length of the starting section or the ending section is too long, resulting in uneven current density distribution during the charging or discharging of the battery cell. However, this application reduces the length of the starting section or the ending section, which can make the length of the starting section or the ending section within a suitable range, reducing the risk of uneven current density distribution and easy lithium plating caused by the length of the starting section or the ending section being too long.

[0184] In one specific embodiment, when the electrode terminal 4 and the tab assembly 3 are close together, it is easier to achieve electrical connection, which can save the cost of the battery cell and reduce the manufacturing difficulty of the battery cell.

[0185] In one specific embodiment, ignoring the width of the electrode and considering its thickness, the electrode is abstracted as a two-dimensional model composed of a cathode current collector, cathode active material, separator, anode active material, anode current collector, and electrolyte. The position and distribution of the tabs are defined by die-cut dimensions. Simulations are performed at 25°C using an accessory charging process to observe the current distribution and anode potential changes at different positions of the electrode. Figures 13 to 16 It is evident that during the charging process of the entire battery cell at a low SOC (around 10% SOC), the resistance is lower and the current density is higher near the first tab 31 and / or the second tab 32 (compared to the electrodes further from the tabs along the length extension direction of electrode assembly 2, especially at the beginning and end sections of electrode assembly 2, there is a longer lithium insertion path and a larger current collector resistance). Therefore, the negative electrode near the tabs is more prone to lithium insertion. When the entire cell is at the end of charging (around 99.8% SOC), the negative electrode near the tabs is in a higher lithium insertion state (compared to the electrodes further from the tabs). At the beginning and end sections, where the distance between adjacent tabs is greater than 1 / 2, the lithium insertion resistance is relatively small due to the relatively low SOC, making it prone to sudden current increases. This causes the anode potential to drop beyond the lithium plating window, a phenomenon clearly observed in simulation results before improving the die-cutting dimensions. After optimizing the tab arrangement, from... Figure 16The simulation results show that by controlling the size of the starting and ending sections to be less than 1 / 2 the distance between adjacent tabs, the non-uniformity of the lithium intercalation state in the starting and ending sections during the entire charging process is reduced, the non-uniformity of the current distribution is reduced, thereby solving the problem of anode potential change and reducing the risk of lithium plating in the starting and ending sections.

[0186] The specific experimental data are as follows:

[0187] Table 1

[0188]

[0189] Table 2

[0190]

[0191]

[0192] Table 3

[0193] Serial Number Test procedure (25℃) 1) 3.5C CC 0.2C0Ah 2) 2.89C CC 0.05C0Ah 3) 2.65C CC 0.05C0Ah 4) 2.36C CC 0.05C0Ah 5) 2.12C CC 0.05C0Ah 6) 1.94C CC 0.05C0Ah 7) 1.83C CC 0.05C0Ah 8) 1.73C CC 0.05C0Ah 9) 1.59C CC 0.05C0Ah 10) 1.4C CC 0.05C0Ah 11) 1.0C CC 0.05C0Ah 12) 0.88C CC 0.05C0Ah 13) 0.6C CC 0.05C0Ah 14) 0.33C CC 0.15C0Ah 15) 0.10C CC 0.02C0Ah or 3.8V 16) 0.05C CC 0.03C0Ah or 3.8V

[0194] Numerical simulations were performed based on the parameters in Tables 1, 2, and 3 above. The simulation data results are shown in the figure below. Figures 13 to 16 As shown in the analysis, it can be seen that, Figure 13 and Figure 14As shown, in the reference example (the unfolded length of the initial segment or the unfolded length of the final segment is greater than half the unfolded length of the first loop; since the current transmission path is observed by unfolding the wound electrode, the effects of the initial segment and the final segment are equivalent, so we take the first cut as one of the cases for simulation), curve a1 is the current distribution at different positions of the electrode under 10% SOC (State of Charge), curve b1 is the current distribution at different positions of the electrode under 50% SOC (State of Charge), curve c1 is the current distribution at different positions of the electrode under 99.8% SOC (State of Charge), curve d1 is the anode potential distribution at different positions of the electrode under 10% SOC (State of Charge), curve e1 is the anode potential distribution at different positions of the electrode under 50% SOC (State of Charge), and curve f1 is the anode potential distribution at 99.8% SOC (State of Charge). The graph shows the anode potential distribution at different locations on the electrode under 10% SOC (State of Charge). It can be seen that during the initial charging phase (10% SOC), the current is higher at the electrode where the tab is located, and the anode potential decreases further away from the tab. During the final charging phase (99.8% SOC), the voltage of the entire cell increases significantly, and current reversal occurs. The current at the electrode where the tab is located decreases, while the current increases further away from the tab, resulting in a lower anode potential. The current reversal is most pronounced near the beginning of the charging phase, increasing the risk of lithium plating.

[0195] like Figure 15 and Figure 16As shown, under the structural experiment of this application (the unfolded length of the initial segment and the unfolded length of the final segment are shorter than half the unfolded length of the first loop), curve a2 is the current distribution at different positions of the electrode under 10% SOC (State of Charge), curve b2 is the current distribution at different positions of the electrode under 50% SOC (State of Charge), curve c2 is the current distribution at different positions of the electrode under 99.8% SOC (State of Charge), curve d2 is the anode potential distribution at different positions of the electrode under 10% SOC (State of Charge), curve e2 is the anode potential distribution at different positions of the electrode under 50% SOC (State of Charge), and curve f2 is the anode potential distribution at 99.8% SOC (State of Charge). The graph shows the anode potential distribution at different locations on the electrode under state of charge (SOC). It indicates that during the initial charging phase (10% SOC), the current is high at the electrode where the tab is located, and the anode potential decreases further away from the tab. During the final charging phase (99.8% SOC), the battery cell voltage rises significantly, causing current reversal. The current at the electrode where the tab is located decreases, while the current increases further away from the tab, resulting in a lower anode potential. Because the length of the initial section is controlled, the current reversal near the initial section is not significant, greatly reducing the risk of lithium plating in the battery cells. The electrode is either the first electrode 21 or the second electrode 22, and the tab is either the first tab 31 or the second tab 32.

Claims

1. A battery cell, characterized in that, It includes a housing and at least one electrode assembly, the electrode assembly including a stacked and wound electrode assembly and a tab assembly connected to the electrode assembly; Along the unfolding direction of the stacked and wound electrode assembly, the electrode assembly includes a starting segment, a first loop, an intermediate loop and a closing segment connected in sequence. A tab assembly is connected to both the first loop and the intermediate loop. At least one of the unfolding length of the starting segment and the unfolding length of the closing segment is shorter than half the unfolding length of the first loop. When the electrode assembly is viewed from the side where the tab assembly is located along the winding axis, the dimension of the electrode assembly along the first direction is smaller than the dimension along the second direction. The first direction and the second direction are perpendicular to each other and both are perpendicular to the winding axis direction. Furthermore, relative to the center line of the electrode assembly extending along the first direction, the starting end of the starting segment, the ending end of the ending segment, and the tab assembly are located on the same side. Moreover, when projected onto the same projection plane along the first direction, the projections of the same-type tabs in the tab assembly overlap each other, and the projections of the opposite-type tabs are spaced apart from each other.

2. The battery cell according to claim 1, characterized in that, The stacked and wound electrode assembly includes a straight portion and a bent portion, the bent portion being connected to both ends of the straight portion along the second direction. The tab assembly is located in the straight section, and the end of the tapering section is located in the bent section.

3. The battery cell according to claim 1 or 2, characterized in that, The electrode assembly includes a first electrode, a second electrode, and a separator, which are stacked and wound together. The first electrode and the second electrode have opposite polarities, and the separator is used to isolate the first electrode and the second electrode. The electrode assembly includes a plurality of first electrodes and a plurality of second electrodes, each first electrode being connected to a first electrode plate and each second electrode being connected to a second electrode plate; The first electrode includes a first starting segment, a first first loop, a first intermediate loop, and a first ending segment connected in sequence; the second electrode includes a second starting segment, a second first loop, a second intermediate loop, and a second ending segment connected in sequence. Two first electrode tabs are provided in the first first ring, and one first electrode tab is provided in each first middle ring. Two second electrode tabs are provided in the second first ring, and one second electrode tab is provided in each second middle ring. The first first turn is the first full turn starting from the first first tab of the starting segment closest to the first electrode plate, and the second first turn is the first full turn starting from the first second tab of the starting segment closest to the second electrode plate.

4. The battery cell according to claim 3, characterized in that, When the electrode assembly is viewed from the side where the tab assembly is located along the winding axis, the end of the first tail section, the end of the second tail section, a first tab located in the first first loop, a first tab located in each of the first intermediate loops, a second tab located in the second first loop, and a second tab located in each of the second intermediate loops are located in the same quadrant. Furthermore, the two first tabs located in the first first loop are located in quadrants adjacent to each other along the first direction, and the two second tabs located in the second first loop are located in quadrants adjacent to each other along the first direction. Here, the center line of the electrode assembly extending along the first direction intersects with the center line extending along the second direction to form four quadrants.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The tab assembly is connected to the same side of the electrode assembly along the winding axis.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The dimensions of the electrode assembly along the second direction are in the range of 200 mm to 600 mm.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The dimensions of the electrode assembly along the first direction are in the range of 10 mm to 50 mm.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The dimensions of the electrode assembly along the winding axis are in the range of 50 mm to 350 mm.

9. The battery cell according to any one of claims 1 to 8, characterized in that, The electrode assembly includes a first electrode, a second electrode, and an insulating member that are stacked and wound together. The first electrode and the second electrode have opposite polarities. The tab assembly includes a plurality of first tabs and a plurality of second tabs. Each first tab is connected to and extends from the first electrode, and each second tab is connected to and extends from the second electrode.

10. The battery cell according to claim 9, characterized in that, Along the first direction, each of the first tabs extends from the first electrode plate by the same length, and each of the second tabs extends from the second electrode plate by the same length; or, Along the first direction from one side to the other, the length of each first electrode tab extending from the first electrode plate gradually increases, and the length of each second electrode tab extending from the second electrode plate gradually increases.

11. The battery cell according to claim 9 or 10, characterized in that, Each of the first electrode tabs is formed such that, along the first direction from one side to the other, the width of each of the first electrode tabs along the second direction decreases. Each of the second electrode tabs is formed such that, along the first direction from one side to the other, the width of each of the second electrode tabs along the second direction decreases.

12. The battery cell according to any one of claims 9 to 11, characterized in that, The battery cell further includes a first electrode terminal and a second electrode terminal. The first electrode terminal is disposed on the housing and connected to each of the first tabs, and the second electrode terminal is disposed on the housing and connected to each of the second tabs. Along the winding axis, relative to the electrode assembly, the first electrode terminal and the second electrode terminal are located on the same side as the first tab and the second tab.

13. The battery cell according to claim 12, characterized in that, The first electrode terminal, the second electrode terminal, the first tab, and the second tab are located on the same side relative to the center line extending along the first direction of the electrode assembly.

14. A battery device, characterized in that, It includes at least one battery cell according to any one of claims 1 to 13.

15. An electrical appliance, characterized in that, It includes at least one battery cell as described in any one of claims 1 to 13, or it includes at least one battery device as described in claim 14.

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