Electrode assembly, battery cell, battery, and method and device for manufacturing electrode assembly

Abstract

To provide an electrode assembly, a battery cell, and a method and a device for manufacturing a battery and an electrode assembly, which reduce the occurrence of a lithium deposition phenomenon.SOLUTION: The present disclosure relates to a battery assembly (22), a battery cell (20), a battery (100) and a method and apparatus (2000) for manufacturing the battery assembly (22), which belong to the technical field of batteries, comprising a first pole piece (221) and a second pole piece (222), the first and second pole pieces being wound in a winding direction (A) to form a winding structure comprising a bending region (223), the first pole piece comprising a first segment (2211) exceeding a 225b of a winding starting end of the second pole piece, a part of the first segment providing a supporting force to an outer part of the first segment of the bending region of the first and second pole pieces; In this way, the structure of the bending region of the first and second electrode plates is compact, and the gap between the bending region portion of the first electrode plate and the bending region portion of the second electrode plate is less likely to increase under the action of an external force, thereby reducing the occurrence of the lithium precipitation phenomenon.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present application relates to the field of battery technology, and in particular to electrode assemblies, battery cells, batteries, and methods and devices for manufacturing battery electrode assemblies. [Background technology]

[0002] Currently, the batteries most commonly used in vehicles are generally lithium-ion batteries, which, as rechargeable batteries, have advantages such as small volume, high energy density, high power density, many recyclability, and long storage time.

[0003] A rechargeable battery includes an electrode assembly and an electrolyte, the electrode assembly being composed of a second electrode sheet, a first electrode sheet, and a separator. Rechargeable batteries operate primarily by relying on the transfer of metal ions between the second and first electrode sheets.

[0004] Lithium deposition is a common abnormal phenomenon in lithium batteries, caused by anomalies such as insufficient space for lithium to be embedded in the negative electrode, excessive resistance to lithium ion migration, or lithium ions escaping from the positive electrode too quickly but unable to be embedded in the negative electrode in equal amounts. The lithium ions that cannot be embedded in the negative electrode can only obtain electrons on the surface of the negative electrode, resulting in the formation of elemental lithium. Lithium deposition affects the charging efficiency and energy density of lithium ions, and if the lithium deposition is severe, lithium crystals may also form. These lithium crystals may penetrate the separator, causing internal short-circuiting and thermal runaway, seriously threatening the safety of the battery. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, how to reduce lithium deposition is an urgent technical problem to be solved in battery technology. [Means for solving the problem]

[0006] The embodiments of the present application provide an electrode assembly, a battery cell, a battery, and a method and device for manufacturing an electrode assembly that can effectively reduce the occurrence of lithium deposition.

[0007] In a first aspect, an embodiment of the present application provides an electrode assembly including a first electrode sheet and a second electrode sheet, the first electrode sheet and the second electrode sheet being wound along a winding direction to form a wound structure, the wound structure including a bent region, the first electrode sheet including a first segment that extends beyond the winding start end of the second electrode sheet, and at least a portion of the first segment being used to provide support to portions of the first electrode sheet and the second electrode sheet that are located outside the first segment in the bent region.

[0008] In the above proposal, the first electrode sheet includes a first segment that extends beyond the starting end of the winding of the second electrode sheet, and the first segment can provide support to the portions of the first electrode sheet and the second electrode sheet that are located outside the first segment in the bending region, thereby making the structure of the portions of the first electrode sheet and the second electrode sheet in the bending region more compact and making the gap between the portions of the first electrode sheet in the bending region and the portions of the second electrode sheet in the bending region less likely to become large due to the action of external force, thereby reducing the occurrence of lithium deposition.

[0009] In some embodiments, the first electrode sheet further includes a second segment arranged continuously with the first segment along the winding direction, the boundary between the first segment and the second segment being located inside the winding start end of the second electrode sheet, and at least a portion of the first segment being supported inside the second segment in the bending region.

[0010] In the above proposal, the boundary between the first segment and the second segment is located inside the starting end of the winding of the second electrode sheet, and the portion of the first segment in the bending region is supported on the inside of the second segment, so that the support force provided by the portion of the first segment in the bending region is first transmitted to the second segment and then transmitted to the second electrode sheet via the second segment, thereby allowing the first segment to play a better supporting role for the portion of the first electrode sheet in the bending region and the portion of the second electrode sheet in the bending region.

[0011] In some embodiments, the electrode assembly further includes a separator for separating the first electrode sheet and the second electrode sheet, and a portion of the first segment in the bending region is supported inside the second segment by the separator.

[0012] In the above proposal, the separator serves to isolate the first electrode sheet from the second electrode sheet, thereby reducing the risk of a short circuit between the first electrode sheet and the second electrode sheet. The portion of the first segment in the bending region is supported inside the second segment by the separator, and the support force provided by the portion of the first segment in the bending region is transmitted to the second segment through the separator, allowing the separator to isolate the portion of the first segment in the bending region from the portion of the second segment in the bending region.

[0013] In some embodiments, the second segment includes a first sub-segment arranged contiguously with the first segment along the winding direction, the first sub-segment having only one surface facing the active material layer of the second electrode sheet, the first sub-segment winding one turn from the boundary outward along the winding direction, the first segment including a bending portion bent and arranged in the bending region, and the bending portion being supported by the first sub-segment in the bending region.

[0014] In the above scheme, the bending portion of the first segment is supported by the first sub-segment in the bending region, and the bending portion is in a bending state in the bending region, which can create a good supporting effect for the first sub-segment.

[0015] In some embodiments, both surfaces of the first sub-segment are coated with an active material layer, or the surface of the first sub-segment facing the active material layer of the second electrode sheet is coated with an active material layer, and the other surface of the first sub-segment is not coated with an active material layer.

[0016] In the above proposal, an active material layer may be applied to both sides of the first sub-segment, thereby simplifying the manufacturing process of the first electrode sheet and making it easier to form the first electrode sheet; an active material layer may be applied to the side of the first sub-segment facing the active material layer of the second electrode sheet, and no active material layer may be applied to the other side of the first sub-segment, thereby reducing the amount of active material layer used on the first electrode sheet and reducing the manufacturing cost of the first electrode sheet.

[0017] In some embodiments, the second segment further includes a second sub-segment and a third sub-segment, and the first segment, the first sub-segment, the second sub-segment, and the third sub-segment are arranged sequentially along the winding direction, both surfaces of the second sub-segment face the active material layer of the second electrode sheet, and only one surface of the third sub-segment faces the active material layer of the second electrode sheet, wherein an active material layer is applied to both surfaces of the third sub-segment, or an active material layer is applied to the surface of the third sub-segment facing the active material layer of the second electrode sheet, and no active material layer is applied to the other surface of the third sub-segment.

[0018] In the above proposal, only one side of the third subsegment faces the active material layer of the second electrode sheet, and both sides of the third subsegment may be coated with an active material layer, thereby simplifying the manufacturing process of the first electrode sheet and making it easier to form the first electrode sheet; the side of the third subsegment facing the active material layer of the second electrode sheet is coated with an active material layer, and the other side of the third subsegment does not need to be coated with an active material layer, thereby reducing the amount of active material layer used on the first electrode sheet and reducing the manufacturing cost of the first electrode sheet.

[0019] In some embodiments, the second segment further includes a fourth subsegment, and the first segment, the first subsegment, the second subsegment, the third subsegment, and the fourth subsegment are arranged sequentially along the winding direction, and neither of the two surfaces of the fourth subsegment faces the active material layer of the second electrode sheet, and an active material layer is applied to both surfaces of the fourth subsegment, or an active material layer is applied to an inner surface of the fourth subsegment, and no active material layer is applied to the other surface of the fourth subsegment.

[0020] In the above proposal, neither side of the fourth subsegment faces the active material layer of the second electrode sheet, and both sides of the fourth subsegment may be coated with an active material layer, thereby simplifying the manufacturing process of the first electrode sheet and making it easier to form the first electrode sheet; the inner side of the fourth subsegment may be coated with an active material layer, and the other side of the fourth subsegment may not be coated with an active material layer, thereby reducing the amount of active material used on the first electrode sheet and cutting the manufacturing cost of the first electrode sheet.

[0021] In some embodiments, the winding structure further includes a linear region, both ends of which are provided with the curved region, and the winding start end of the first electrode sheet is located within the linear region, and / or the winding start end of the second electrode sheet is located within the linear region.

[0022] In the above proposal, in order to wind the first electrode sheet and the second electrode sheet, the winding start end of the first electrode sheet can be located within a linear region, and the winding start end of the second electrode sheet can also be located within a linear region position.

[0023] In some embodiments, the first segment extends from the boundary in a spiral inward direction, bypassing one of the bend regions.

[0024] In the above proposal, the first segment extends from the boundary with the second segment inward, winding around it and bypassing one of the bend regions, i.e., the first segment can provide support to the portions of the first and second electrode sheets in the bend region. The first segment in this structure is short, saving material and reducing costs.

[0025] In some embodiments, both the winding start end of the first electrode sheet and the winding start end of the second electrode sheet are located within the straight region, the two bent regions are located at both ends of the straight region in a first direction, the portion of the first electrode sheet extending from the winding start end of the first electrode sheet to one bent region and the portion of the second electrode sheet extending from the winding start end of the second electrode sheet to the other bent region are offset from each other in a second direction, and the second direction is perpendicular to the first direction and the straight region.

[0026] In the above proposal, the portion of the first electrode sheet extending from the winding start end of the first electrode sheet to one of the bent regions and the portion of the second electrode sheet extending from the winding start end of the second electrode sheet to the other bent region are offset from each other in the second direction. This structure effectively reduces the difference in thickness on both sides of the winding structure in the first direction, ensures consistency in thickness on both sides of the winding structure in the first direction, and improves the energy density of the electrode assembly.

[0027] In some embodiments, the first segment extends from the boundary in a spiral inward direction, bypassing two of the bend regions.

[0028] In the above proposal, the first segment extends by winding inward from the boundary with the second segment, bypassing the two bent regions; that is, the first segment can provide support to the portions of the first and second electrode sheets within the two bent regions, thereby making the structure of the portions of the first and second electrode sheets in the two bent regions more compact and reducing the occurrence of lithium deposition.

[0029] In some embodiments, the first electrode sheet is a negative electrode sheet and the second electrode sheet is a positive electrode sheet.

[0030] In the above proposal, the first electrode sheet and the second electrode sheet are the negative electrode sheet and the positive electrode sheet, respectively. The first segment of the first electrode sheet extends beyond the winding start end of the second electrode sheet, and there is no portion of the second electrode sheet corresponding to the first segment. Therefore, the first segment is a portion of the first electrode sheet where lithium is not embedded, and lithium deposition is less likely to occur in the first segment. In addition, the portion of the first electrode sheet located outside the first segment in the bending region may be supported by the first segment. As a result, the radius of curvature of this portion is increased, and the risk of the innermost ring of the portion of the first electrode sheet where lithium is embedded falling off (the active material layer falling off) in the bending region due to an insufficient radius of curvature is reduced, thereby causing lithium deposition.

[0031] In some embodiments, both surfaces of the first segment are coated with a negative electrode active material layer.

[0032] In the above scheme, negative electrode active material layers are applied to both surfaces of the first segment, so the overall thickness of the first segment is large, improving the support capacity of the first segment.

[0033] In a second aspect, an embodiment of the present application includes a case and an electrode assembly provided by any embodiment of the first aspect,

[0034] The electrode assembly provides a battery cell housed within the case.

[0035] In the above proposal, the first segment of the first electrode sheet of the electrode assembly can provide support to the portions of the first electrode sheet and the second electrode sheet in the bending region located outside the first segment, thereby making the structure of the portions in the bending region of the first electrode sheet and the second electrode sheet more compact and making the gap between the portions in the bending region of the first electrode sheet and the portions in the bending region of the second electrode sheet less likely to become large due to the action of external force, reducing the occurrence of lithium precipitation, improving the safety of the battery cell, and extending the service life of the battery cell.

[0036] In a third aspect, embodiments of the present application provide a battery comprising a housing and a battery cell provided by any of the embodiments of the second aspect, the battery cell being housed within the housing.

[0037] In a fourth aspect, embodiments of the present application provide an electrical device comprising a battery provided by any embodiment of the third aspect.

[0038] In a fifth aspect, the present embodiment comprises: The present invention provides a method for manufacturing an electrode assembly, the method including the steps of: providing a first electrode sheet and a second electrode sheet; and winding the first electrode sheet and the second electrode sheet along a winding direction to form a wound structure, the wound structure including a bending region, wherein the first electrode sheet includes a first segment that extends beyond the winding start end of the first electrode sheet, and at least a portion of the first segment is used to provide support to portions of the first electrode sheet and the second electrode sheet that are located outside the first segment in the bending region.

[0039] In a sixth aspect, an embodiment of the present application provides a device for manufacturing an electrode assembly, comprising a first providing device, a second providing device, and an assembling device, wherein the first providing device is used to provide a first electrode sheet, the second providing device is used to provide a second electrode sheet, and the assembling device is used to wind the first electrode sheet and the second electrode sheet along a winding direction to form a wound structure, the wound structure comprising a bending region, wherein the first electrode sheet comprises a first segment that extends beyond the winding start end of the first electrode sheet, and at least a portion of the first segment is used to provide support to portions of the first electrode sheet and the second electrode sheet that are located outside the first segment in the bending region. [Brief explanation of the drawings]

[0040] In order to more clearly explain the technical solutions in the embodiments of the present application, the following briefly introduces the drawings necessary for the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without any creative efforts.

[0041] [Figure 1] 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application. [Figure 2] 1 is a structural schematic diagram of a battery provided by some embodiments of the present application. [Figure 3] 3 is a structural schematic diagram of a battery module of the battery shown in FIG. 2. [Figure 4] FIG. 4 is an exploded view of a battery cell of the battery module shown in FIG. [Figure 5] 1 is a structural schematic diagram of an electrode assembly provided by some embodiments of the present application. [Figure 6] FIG. 6 is a structural schematic diagram of the electrode assembly shown in FIG. 5 after deployment. [Figure 7] FIG. 6 is a partially enlarged view of a first segment of the first electrode sheet shown in FIG. 5. [Figure 8]6 is a partial enlarged view of a first sub-segment of the first electrode and a second electrode sheet shown in FIG. 5. FIG. [Figure 9] FIG. 10 is a partial enlarged view of a first sub-segment of a first electrode and a second electrode sheet provided by still other embodiments of the present application. [Figure 10] 6 is a partial enlarged view of a third sub-segment of the first electrode and a second electrode sheet shown in FIG. 5. FIG. [Figure 11] FIG. 10 is a partial enlarged view of a third sub-segment of a first electrode and a second electrode sheet provided according to still other embodiments of the present application. [Figure 12] 6 is a partial enlarged view of a fourth sub-segment of the first electrode and a second electrode sheet shown in FIG. 5. FIG. [Figure 13] FIG. 10 is a partial enlarged view of a fourth sub-segment of a first electrode and a second electrode sheet provided according to still other embodiments of the present application. [Figure 14] 10A and 10B are structural schematic diagrams of electrode assemblies provided by further some embodiments of the present application. [Figure 15] 10A and 10B are structural schematic diagrams of electrode assemblies provided by further some embodiments of the present application. [Figure 16] 10A and 10B are structural schematic diagrams of electrode assemblies provided by further some embodiments of the present application. [Figure 17] 10A and 10B are structural schematic diagrams of electrode assemblies provided by further some embodiments of the present application. [Figure 18] 1 is a flowchart of a method for manufacturing an electrode assembly provided by some embodiments of the present application. [Figure 19] 1 is a schematic block diagram of a manufacturing device for an electrode assembly provided by some embodiments of the present application.

[0042] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION OF THE INVENTION

[0043] In order to clarify the objectives, technical solutions and advantages of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described below clearly and comprehensively with reference to the drawings of the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present application without any creative efforts belong to the protection scope of the present application.

[0044] 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. Terms used in the present specification are for the purpose of describing specific embodiments only and are not intended to limit the present specification. The terms "comprise" and "have" and any variations thereof in the present specification and claims, as well as the above-mentioned drawings, are intended to cover a non-exclusive inclusion. The terms "first," "second," etc. in the present specification and claims or the above-mentioned drawings are used to distinguish different objects, but are not intended to describe a particular order or primary-secondary relationship.

[0045] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearance of such a phrase in various places in the present specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent embodiment or alternative embodiment of other embodiments.

[0046] In the description of this application, it should be understood that unless otherwise specified and limited, the terms "mount," "connect," "couple," and "attach" may be broadly understood to mean, for example, a fixed connection, a detachable connection, or an integral connection, a direct connection, an indirect connection via an intermediate medium, or internal communication between two elements. Those skilled in the art can understand the specific meanings of the above terms in this application according to specific circumstances.

[0047] In the embodiments of the present application, the same reference numerals indicate the same elements, and for the sake of brevity, detailed descriptions of the same elements in different embodiments will be omitted. It should be understood that the dimensions such as thickness, length, width, etc. of various elements in the embodiments of the present application shown in the accompanying drawings, and the overall dimensions such as thickness, length, width, etc. of the integrated device, are merely illustrative and do not constitute limitations on the present application.

[0048] As used herein, "plurality" means two or more (including two).

[0049] In this application, the battery cell may include a lithium ion secondary battery, a lithium ion primary battery, a lithium-sulfur battery, a sodium lithium ion battery, a sodium ion battery, or a magnesium ion battery, etc., but the embodiments of this application are not limited thereto. The battery cell may have a cylindrical, flat, rectangular, or other shape, etc., but the embodiments of this application are not limited thereto. Battery cells are generally divided into three types according to packaging methods: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, but the embodiments of this application are not limited thereto.

[0050] The battery referred to in the embodiments of this application refers to a single physical module containing one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. The battery generally includes a housing for enclosing one or more battery cells. The housing can prevent liquids or other foreign objects from affecting the charging or discharging of the battery cells.

[0051] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly is composed of a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell operates primarily by relying on the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode current collector. The positive electrode current collector without the positive electrode active material layer protrudes from the positive electrode current collector coated with the positive electrode active material layer and is used as a positive electrode tab. For example, in a lithium-ion battery, the positive electrode current collector may be made of aluminum, and the positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, a ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode current collector without the negative electrode active material layer protrudes from the negative electrode current collector coated with the negative electrode active material layer and is used as a negative electrode tab. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon or silicon, etc. To ensure that they do not melt even when a large current flows, multiple positive electrode tabs are stacked, and multiple negative electrode tabs are stacked. The material of the separator may be PP (polypropylene) or PE (polyethylene), etc.

[0052] In the case of a lithium-ion battery, when charging, lithium ions are released from the positive electrode and inserted into the negative electrode, and when discharging, lithium ions are released from the negative electrode and inserted into the positive electrode. When charging a lithium-ion battery, several abnormal situations can occur, which can cause lithium deposition. For example, the negative electrode may not have enough space for lithium to be inserted, the resistance to lithium ion migration may be too high, or the lithium ions may be released from the positive electrode too quickly but not inserted into the negative electrode in equal amounts. These abnormalities can cause lithium ions that cannot be inserted into the negative electrode to only gain electrons on the surface of the negative electrode, resulting in the formation of elemental lithium, i.e., lithium deposition.

[0053] The inventors discovered that the electrode assembly is prone to lithium deposition in its bent region, and after further research, discovered that after the first electrode sheet and the second electrode sheet are wound into a wound structure using a winding needle, in the process of pulling out the winding needle located at the winding core of the wound structure, the electrode sheet in contact with the winding needle is moved and displaced by the winding needle, resulting in a larger gap between the portion of the first electrode in the bent region and the portion of the second electrode sheet in the bent region, making it prone to lithium deposition during charging.

[0054] In view of this, the embodiments of the present application provide a technical solution in which a first segment of the first electrode sheet that extends beyond the starting end of winding of the second electrode sheet provides support to the portions of the first electrode sheet and the second electrode sheet that are located outside the first segment in the bending regions thereof, thereby making the structure of the portions of the first electrode sheet and the second electrode sheet in the bending regions more compact and making it difficult for the gap between the portions of the first electrode sheet in the bending regions thereof and the portions of the second electrode sheet in the bending regions thereof to become large due to the action of external force, thereby reducing the occurrence of lithium deposition.

[0055] The technical solutions described in the embodiments of the present application are applicable to batteries and electric devices that use batteries.

[0056] The electric devices provided by the embodiments of the present application may be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, electric tools, etc. The vehicles may be fuel-powered vehicles, gasoline-powered vehicles, or new energy vehicles, and the new energy vehicles may be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. The spacecraft may include airplanes, rockets, space shuttles, and spacecraft planes, etc. The electric toys may include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric aircraft toys, etc. The electric tools may include metal cutting electric tools, polishing electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, electric impact drills, concrete vibrators, and electric planers, etc. In the embodiments of the present application, the electric devices are not particularly limited.

[0057] In the following embodiment, for ease of explanation, the electric device is a vehicle.

[0058] Referring to Fig. 1, Fig. 1 is a structural schematic diagram of a vehicle 1000 provided by some embodiments of the present application. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, front, or rear of the vehicle 1000. The battery 100 may be used to supply power to the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000.

[0059] The vehicle 1000 may further include a controller 200 and a motor 300, where the controller 200 is used to control the battery 100 to provide power to the motor 300, for example for operating power needs when starting, navigating, and driving the vehicle 1000.

[0060] In some embodiments of the present application, the battery 100 can provide not only the operating power source for the vehicle 1000 but also the driving power for the vehicle 1000, replacing or partially replacing fuel or natural gas.

[0061] Referring to Figure 2, Figure 2 is an exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 provided in some embodiments of the present application includes a housing 10 and a battery cell 20 (not shown in Figure 2), and the battery cell 20 is housed in the housing 10.

[0062] The housing 10 is used to house the battery cells 20 so as to provide a sealed environment for the battery cells 20. In some embodiments, the housing 10 may include a housing portion 11 and a cover portion 12, where the housing portion 11 is covered by the cover portion 12, and the housing portion 11 and the cover portion 12 jointly define a sealed space 13 for housing the battery cells 20. The housing portion 11 and the cover portion 12 may both be hollow structures open on one side, and the open side of the housing portion 11 is covered by the open side of the cover portion 12, forming the housing 10 having the sealed space 13. Of course, the housing portion 11 and the cover portion 12 may have various shapes, such as a cylindrical body or a rectangular parallelepiped.

[0063] The battery 100 may have one or more battery cells 20. The battery 100 may have a plurality of battery cells 20. The plurality of battery cells 20 may be connected in series, in parallel, or in series-parallel, where series-parallel connection means that the plurality of battery cells 20 are connected in series and in parallel. The plurality of battery cells 20 may be directly connected in series, in parallel, or in series-parallel, and the entirety of the plurality of battery cells 20 may be housed in the housing 10. Naturally, the plurality of battery cells 20 may first be connected in series, in parallel, or in series-parallel to form a battery module 30, and then the plurality of battery modules 30 may be connected in series, in parallel, or in series-parallel to form a whole and housed in the housing 10.

[0064] In some embodiments, referring to FIG. 3, FIG. 3 is a structural schematic diagram of a battery module 30 of the battery 100 shown in FIG. 2. There are a plurality of battery cells 20, and the plurality of battery cells 20 are first connected in series, parallel, or series-parallel to form a battery module 30. The plurality of battery modules 30 are further connected in series, parallel, or series-parallel to form a whole, which is housed in a housing 10.

[0065] In some embodiments, the multiple battery cells 20 in the battery module 30 may be electrically connected via a bus member 31 to achieve a parallel connection, a series connection, or a series-parallel connection of the multiple battery cells 20 in the battery module 30.

[0066] 4, which is an exploded view of the battery cell 20 of the battery module 30 shown in FIG. 3. The battery cell 20 provided by the embodiment of the present application includes a case 21 and an electrode assembly 22, and the electrode assembly 22 is housed in the case 21.

[0067] The case 21 can provide a sealed environment for the electrode assembly 22, and the case 21 is filled with an electrolyte, for example, an electrolyte solution.

[0068] In addition, the battery cell 20 may have one or more electrode assemblies 22 housed in the case 21. For example, in FIG.

[0069] 4 , in some embodiments, the case 21 may include a case body 211 and a cover body 212, where the case body 211 is a hollow structure open on one side, and the cover body 212 covers the opening of the case body 211 to form a sealed connection and form a sealed chamber 213 for accommodating the electrode assembly 22 and the electrolyte. When assembling the battery cell 20, the electrode assembly 22 may be first placed into the case body 211, the case body 211 may be filled with the electrolyte, and then the cover body 212 may cover the opening of the case body 211.

[0070] The case body 211 may have various shapes, such as a cylindrical body or a rectangular parallelepiped. The shape of the case body 211 may be determined according to the specific shape of the electrode assembly 22. For example, if the electrode assembly 22 is cylindrical, the case body 211 may be a cylindrical case 21. If the electrode assembly 22 has a rectangular parallelepiped structure, the case body 211 may be a rectangular parallelepiped case 21. Of course, the cover body 212 may also have various structures, such as a plate-like structure or a hollow structure with one end open. For example, in FIG. 4, the case body 211 has a rectangular parallelepiped structure, and the cover body 212 has a plate-like structure, and the cover body 212 covers an opening at the top of the case body 211.

[0071] 5, which is a structural schematic diagram of an electrode assembly 22 provided in some embodiments of the present application. The electrode assembly 22 provided in the embodiments of the present application includes a first electrode sheet 221 and a second electrode sheet 222, which are wound along a winding direction A to form a wound structure, and the wound structure includes a curved region 223, in which the first electrode sheet 221 includes a first segment 2211 that extends beyond a winding start end 225b of the second electrode sheet 222, and at least a portion of the first segment 2211 is used to provide support to portions of the first electrode sheet 221 and the second electrode sheet 222 that are located outside the first segment 2211 in the curved region.

[0072] The first segment 2211 can provide support to the portions of the first electrode sheet 221 and the second electrode sheet 222 in the bending region 223 located outside the first segment 2211, thereby making the structure of the portions of the first electrode sheet 221 and the second electrode sheet 222 in the bending region 223 more compact, making the gap between the portions of the first electrode sheet 221 in the bending region 223 and the portions of the second electrode sheet 222 in the bending region 223 less likely to become large due to the action of external force, and making the electrode sheet in contact with the winding needle less likely to shift during the process of pulling out the winding needle, thereby reducing the occurrence of lithium deposition.

[0073] The winding direction A is the direction in which the first electrode sheet 221 and the second electrode sheet 222 are wound circumferentially from the inside to the outside, starting from the winding starting end 225b. In Figure 5, the clockwise direction is the winding direction A.

[0074] The first electrode sheet 221 has two ends, a winding start end 225a and a winding end 226a. The winding start end 225a of the first electrode sheet 221 is the supply end of the first electrode sheet 221, i.e., the free end located at the innermost periphery of the first electrode sheet 221, and the winding end 226a of the first electrode sheet 221 is the free end located at the outermost periphery of the first electrode sheet 221. The second electrode sheet 222 also has two ends, a winding start end 225b and a winding end 226b. The winding start end 225b of the second electrode sheet 222 is the supply end of the second electrode sheet 222, i.e., the free end located at the innermost periphery of the second electrode sheet 222, and the winding end 226b of the second electrode sheet 222 is the free end located at the outermost periphery of the second electrode sheet 222.

[0075] The winding structure further includes a linear region 224, and both ends of the linear region 224 are provided with curved regions 223. The two curved regions 223 are located at both ends of the linear region 224 in the first direction B. The linear region 224 is a region in which the winding structure has a linear structure, and both the portion of the first electrode sheet 221 in the linear region 224 and the portion of the second electrode sheet 222 in the linear region 224 are essentially arranged along the first direction B. The curved region 223 is a region in which the winding structure has a curved structure, and both the portion of the first electrode sheet 221 in the curved region 223 and the portion of the second electrode sheet 222 in the curved region 223 are curved and distributed. Exemplarily, the portion of the first electrode sheet 221 in the curved region 223 and the portion of the second electrode sheet 222 in the curved region 223 are arc-shaped.

[0076] The electrode assembly 22 may further include a separator 227, which separates the first electrode sheet 221 and the second electrode sheet 222. The separator 227 has insulating properties and reduces the risk of a short circuit between the first electrode sheet 221 and the second electrode sheet 222. The material of the separator 227 may be PP (polypropylene), PE (polyethylene), or the like.

[0077] In some embodiments, referring to Figure 6, Figure 6 is a schematic diagram of the structure of the electrode assembly 22 shown in Figure 5 after expansion. The electrode assembly 22 may include two separators 227, and the four components of one separator 227, a first electrode sheet 221, the other separator 227, and a second electrode sheet 222 may be sequentially stacked and then wound along a winding direction A (see Figure 5) to form a wound structure.

[0078] In the present embodiment, the polarities of the first electrode sheet 221 and the second electrode sheet 222 are reversed, and the first electrode sheet 221 may be a negative electrode sheet and the second electrode sheet 222 may be a positive electrode sheet, or the first electrode sheet 221 may be a positive electrode sheet and the second electrode sheet 222 may be a negative electrode sheet. When the first electrode sheet 221 is a positive electrode sheet and the second electrode sheet 222 is a negative electrode sheet, the positive electrode active material layer 229 does not need to be applied to both sides of the first segment 2211 of the first electrode sheet 221. That is, the first segment 2211 of the first electrode sheet 221 has only a positive electrode current collector and no positive electrode active material layer 229, thereby reducing the occurrence of lithium deposition. When the first electrode sheet 221 is a negative electrode sheet and the second electrode sheet 222 is a positive electrode sheet, the negative electrode active material layer 228 does not need to be applied to both sides of the first segment 2211 of the first electrode sheet 221, or the negative electrode active material layer 228 may be applied to at least one side. In other words, the first segment 2211 of the first electrode sheet 221 may include only a negative electrode current collector, or may include a negative electrode current collector and a negative electrode active material layer 228 applied to the negative electrode current collector.

[0079] In some embodiments, the first electrode sheet 221 is a negative electrode sheet, and the second electrode sheet 222 is a positive electrode sheet. Referring to Figure 7, Figure 7 is a partially enlarged view of the first segment 2211 of the first electrode sheet 221 shown in Figure 5. Since the negative electrode active material layer 228 is applied to both sides of the first segment 2211 of the first electrode sheet 221, the overall thickness of the first segment 2211 is increased, and the support capacity of the first segment 2211 is improved.

[0080] In a typical electrode assembly 22, the innermost electrode sheet in the bending region 223 generally has the greatest degree of bending, i.e., the innermost electrode sheet in the bending region 223 has the smallest radius of curvature, and is therefore most likely to undergo shedding (shedding of the active material layer). If the innermost electrode sheet is a negative electrode sheet, there is a high risk of lithium deposition.

[0081] Meanwhile, in this embodiment, the first electrode sheet 221 is the negative electrode sheet, and the first segment 2211 of the first electrode sheet 221 exceeds the winding start end 225b of the second electrode sheet 222, and at least a portion of the first segment 2211 is located in the bending region 223 to provide support for the first electrode sheet 221 and the second electrode sheet 222 outside it. Therefore, the electrode sheet located at the innermost side of the bending region 223 of the electrode assembly 22 is the first segment 2211, and the second electrode sheet 222 does not have a portion corresponding to the first segment 2211. The first segment 2211 is a portion of the first electrode sheet where lithium is not embedded, and the curvature radius of the portion of the first segment 2211 in the bending region 223 is too small, so lithium deposition is not likely to occur even if powder is removed (the active material layer falls off). In addition, the portion of the first electrode sheet 221 located outside the first segment 2211 in the bending region 223 may be supported by the first segment 2211, resulting in a larger radius of curvature for this portion, and the innermost periphery of the portion of the first electrode sheet 221 in which lithium is embedded has a radius of curvature that is too small, reducing the risk of powder shedding (the active material layer falling off) and causing the risk of lithium precipitation.

[0082] 5 , in some embodiments, the first electrode sheet 221 further includes a second segment 2212 arranged continuously with the first segment 2211 along the winding direction A, and the boundary (first boundary a) between the first segment 2211 and the second segment 2212 is located inside the winding start end 225b of the second electrode sheet 222. At least a portion of the first segment 2211 is supported inside the second segment 2212 in the bent region 223.

[0083] The support force provided by the portion of the first segment 2211 in the bending region 223 can be first transmitted to the second segment 2212 and then transmitted to the second electrode sheet 222 via the second segment 2212, thereby allowing the first segment 2211 to play a better supporting role for the portion of the first electrode sheet 221 in the bending region 223 and the portion of the second electrode sheet 222 in the bending region 223.

[0084] The second segment 2212 is the portion of the first electrode sheet 221 in which lithium is embedded; when charging, the lithium ions are detached from the second electrode sheet 222 and embedded in the second segment 2212; when discharging, the lithium ions are detached from the second segment 2212 and embedded in the second electrode sheet 222.

[0085] In a typical electrode assembly 22, the supply end of the first electrode sheet 221 is located within the straight region 224. After the first electrode sheet 221, the second electrode sheet 222, and the separator 227 are wound into a wound structure by the winding needle, friction occurs between the winding needle and the first electrode 221. In the process of pulling out the winding needle from the winding core position of the wound structure, the winding needle moves and displaces the innermost portion of the curved region 223 of the second segment 2212. As a result, the gap between the innermost portion of the curved region 223 of the second segment 2212 and the second electrode sheet 222 becomes larger, making it easy for lithium deposition to occur during charging.

[0086] On the other hand, in this embodiment, at least a portion of the first segment 2211 is supported inside the second segment 2212 in the bending region 223, and in the process of pulling out the winding needle, the winding needle is not easily displaced by moving the part of the second segment 2212 located at the innermost position in the bending region 223, thereby reducing the occurrence of lithium deposition.

[0087] At least a portion of the first segment 2211 is supported inside the second segment 2212 in the bending region 223, and the portion of the first segment 2211 in the bending region 223 may be in direct contact with the second segment 2212 and supported inside the second segment 2212, or the portion of the first segment 2211 in the bending region 223 may be supported inside the second segment 2212 by a separator 227, and the separator 227 can isolate the portion of the first segment 2211 in the bending region 223 from the portion of the second segment 2212 in the bending region 223, and the portion of the first segment 2211 located in the bending region 223 may be in contact with the separator 227, and the separator 227 may be in contact with the second segment 2212, and the support force provided by the portion of the first segment 2211 in the bending region 223 may be transmitted to the second segment 2212 via the separator 227.

[0088] 5, the portion of the first segment 2211 in the bent region 223 is supported inside the second segment 2212 by the separator 227. The separator 227 extends beyond the winding start end 225a of the first electrode sheet 221, and the portion of the separator 227 extending beyond the winding start end 225a of the first electrode sheet 221 is wound toward the inside of the first segment 2211.

[0089] 5 , in some embodiments, the second segment 2212 includes a first sub-segment 2212a disposed contiguously with the first segment 2211 along the winding direction A. That is, the first sub-segment 2212a borders the first segment 2211. Only one side of the first sub-segment 2212a faces the active material layer of the second electrode sheet 222. The first sub-segment 2212a winds one turn from the boundary with the first segment 2211 toward the outside along the winding direction A. The first segment 2211 includes a bent portion 2211a bent in a bent region 223, and the bent portion 2211a is supported by the first sub-segment 2212a in the bent region 223. The bent portion 2211a is bent in the bent region 223 and can provide good support for the first sub-segment 2212a.

[0090] Here, the boundary between the first sub-segment 2212a and the first segment 2211 is a first boundary a. The portion of the first segment 2211 in the bending region 223 is a bending portion 2211a. Illustratively, the bending portion 2211a has an arc shape.

[0091] Since the first boundary a is located inside the winding start portion 225b of the second electrode sheet 222 and there is no second electrode sheet 222 inside the first sub-segment 2212a, only one side of the first sub-segment 2212a faces the active material layer of the second electrode sheet 222; that is, the inner surface of the first sub-segment 2212a does not face the active material layer of the second electrode sheet 222, and the outer surface of the first sub-segment 2212a faces the active material layer of the adjacent second electrode sheet 222 located outside it.

[0092] The active material layer of the first sub-segment 2212a may have various configurations, for example, referring to Figure 8, which is a partially enlarged view of the first sub-segment 2212a of the first electrode and the second electrode sheet 222 shown in Figure 5. An active material layer may be applied to both sides of the first sub-segment 2212a, and the active material layer may be a negative electrode active material layer 228, thereby simplifying the manufacturing process of the first electrode sheet 221 and making it easier to form the first electrode sheet 221. Referring to Figure 9, Figure 9 is a partially enlarged view of the first sub-segment 2212a and the second electrode sheet 222 of a first electrode provided in some other embodiments of the present application. An active material layer may be applied to the surface of the first sub-segment 2212a facing the active material layer of the second electrode sheet 222, and the active material layer on the first sub-segment 2212a may be a negative electrode active material layer 228, and the active material layer on the second electrode sheet 222 may be a positive electrode active material layer 229. No active material layer may be applied to the other side of the first sub-segment 2212a, thereby reducing the amount of active material layer used on the first electrode sheet 221 and reducing the manufacturing cost of the first electrode sheet 221.

[0093] During the charge / discharge process, lithium is released and inserted between the active material layer on the inner surface of the first sub-segment 2212a and the active material layer of the second electrode sheet 222.

[0094] For example, the active material layer on the first electrode sheet 221 is a negative electrode active material layer 228, the active material layer on the outer surface of the first sub-segment 2212a is a negative electrode active material layer 228, and the active material layer on the second electrode sheet 222 is a positive electrode active material layer 229. The positive electrode active material layer 229 is applied to both surfaces of the entire segment of the second electrode sheet 222 from the winding start end 225b to the winding end 226b.

[0095] 5, in some embodiments, the second segment 2212 may further include a second sub-segment 2212b and a third sub-segment 2212c. The first segment 2211, the first sub-segment 2212a, the second sub-segment 2212b, and the third sub-segment 2212c are sequentially and continuously arranged along the winding direction A, with both surfaces of the second sub-segment 2212b facing the active material layer of the second electrode sheet 222, and only one surface of the third sub-segment 2212c facing the active material layer of the second electrode sheet 222.

[0096] Here, second sub-segment 2212b borders first sub-segment 2212a, and third sub-segment 2212c borders second sub-segment 2212b. The border between second sub-segment 2212b and first sub-segment 2212a is second border b, and the border between third sub-segment 2212c and second sub-segment 2212b is third border c. Because first sub-segment 2212a winds one turn outward from the border with first segment 2211 along winding direction A, second border b is located outside first border a.

[0097] An active material layer is applied to both sides of the second sub-segment 2212b. Both sides of the second sub-segment 2212b face the active material layer of the second electrode sheet 222. That is, the active material layer applied to the inner surface of the second sub-segment 2212b faces the active material layer of the second electrode sheet 222 located on the inner side and adjacent to it, and the active material layer applied to the outer surface of the second sub-segment 2212b faces the active material layer of the second electrode sheet 222 located on the outer side and adjacent to it. During charge and discharge processes, lithium is released from and inserted between the active material layer applied to the inner surface of the second sub-segment 2212b and the active material layer of the second electrode sheet 222 located on the inner side and adjacent to it, and lithium is released from and inserted between the active material layer applied to the outer surface of the second sub-segment 2212b and the active material layer of the second electrode sheet 222 located on the outer side and adjacent to it.

[0098] Only one surface of the third sub-segment 2212c faces the active material layer of the second electrode sheet 222. That is, the outer surface of the third sub-segment 2212c does not face the active material layer of the second electrode sheet 222, but faces the active material layer of the second electrode sheet 222 located inside and adjacent to it. For example, as shown in FIG. 5 , the second electrode sheet 222 is not provided on the outside of the third sub-segment 2212c, and as a result, the outer surface of the third sub-segment 2212c does not face the active material layer of the second electrode sheet 222.

[0099] The active material layer of the third sub-segment 2212c may have various configurations. For example, FIG. 10 is a partially enlarged view of the third sub-segment 2212c and second electrode sheet 222 of the first electrode shown in FIG. 5. An active material layer may be applied to both sides of the third sub-segment 2212c, and the active material layer may be a negative electrode active material layer 228. FIG. 11 is a partially enlarged view of the third sub-segment 2212c and second electrode sheet 222 of the first electrode according to some other embodiments of the present disclosure. An active material layer may be applied to the side of the third sub-segment 2212c facing the active material layer of the second electrode sheet 222, and the active material layer on the third sub-segment 2212c may be a negative electrode active material layer 228, and the active material layer on the second electrode sheet 222 may be a positive electrode active material layer 229. No active material layer is applied to the other side of the third sub-segment 2212c.

[0100] In some embodiments, still referring to FIG. 5, the second segment 2212 may further include a fourth sub-segment 2212d, where the first segment 2211, the first sub-segment 2212a, the second sub-segment 2212b, the third sub-segment 2212c and the fourth sub-segment 2212d are arranged sequentially and continuously along the winding direction A, and neither side of the fourth sub-segment 2212d faces the active material layer of the second electrode sheet 222.

[0101] Here, the fourth sub-segment 2212d borders the third sub-segment 2212c, and the boundary between the fourth sub-segment 2212d and the third sub-segment 2212c is the fourth boundary d.

[0102] Neither of the opposite surfaces of the fourth sub-segment 2212d faces the active material layer of the second electrode sheet 222. That is, neither the inner surface nor the outer surface of the fourth sub-segment 2212d faces the active material layer of the second electrode sheet 222. Illustratively, since the fourth sub-segment 2212d extends beyond the winding end 226b of the second electrode sheet 222, neither of the opposite surfaces of the fourth sub-segment 2212d faces the active material layer of the second electrode sheet 222.

[0103] When the second electrode sheet 222 is a negative electrode sheet, by providing the second electrode sheet 222 with a fourth sub-segment 2212d that extends beyond the winding end 226b of the second electrode sheet 222, the occurrence of lithium precipitation at the end portion of the first electrode sheet 221 can be effectively reduced.

[0104] The active material layer of the fourth sub-segment 2212d may have various configurations. For example, FIG. 12 is a partially enlarged view of the fourth sub-segment 2212d of the first electrode and the second electrode sheet 222 shown in FIG. 5. An active material layer may be applied to both sides of the fourth sub-segment 2212d, and the active material layer may be the negative electrode active material layer 228. FIG. 13 is a partially enlarged view of the fourth sub-segment 2212d of the first electrode and the second electrode sheet 222 provided by some other embodiments of the present application. An active material layer is applied to the inner surface of the fourth sub-segment 2212d, and no active material layer is applied to the other surface of the fourth sub-segment 2212d, i.e., an active material layer is applied to the inner surface of the fourth sub-segment 2212d, and no active material layer is applied to the outer surface of the fourth sub-segment 2212d, and the active material layer of the fourth sub-segment 2212d may be the negative electrode active material layer 228.

[0105] The fourth sub-segment 2212d is an end segment of the first electrode sheet 221, and the first electrode sheet 221 may end in the curved region 223 or in the straight region 224. That is, the fourth sub-segment 2212d may be located in the curved region 223 or in the straight region 224. Exemplarily, in FIG. 5, the fourth sub-segment 2212d is located in the curved region 223.

[0106] The end of the fourth sub-segment 2212d away from the third sub-segment 2212c is the winding end 226a of the first electrode sheet 221. The separator 227 can be wound a certain distance along the winding direction A beyond the winding end 226a of the first electrode sheet 221.

[0107] For example, the length of the fourth sub-segment 2212d may range from 3 mm to 15 mm.

[0108] As can be seen from the above several embodiments, the boundary (first boundary a) between the first segment 2211 and the second segment 2212 may be located inside the winding start end 225b of the second electrode sheet 222. In some other embodiments, refer to FIG. 14, which is a structural schematic diagram of the electrode assembly 22 provided according to some other embodiments of the present application. The boundary (first boundary a) between the first segment 2211 and the second segment 2212 may be located outside the winding start end 225b of the second electrode sheet 222. In this case, at least a portion of the first segment 2211 is supported inside the second electrode sheet 222 in the bent region 223.

[0109] At least a portion of the first segment 2211 is supported on the inside of the second electrode sheet 222 in the bending region 223, and the portion of the first segment 2211 in the bending region 223 may be in direct contact with the second electrode sheet 222 and supported on the inside of the second electrode sheet 222, or the portion of the first segment 2211 in the bending region 223 may be supported on the inside of the second electrode sheet 222 by a separator 227, which can isolate the first segment 2211 and the second electrode sheet 222, and the portion of the first segment 2211 in the bending region 223 is in contact with the separator 227, and the separator 227 is in contact with the second electrode sheet 222 to realize force transmission.

[0110] In this embodiment, the first electrode sheet 221 may be a positive electrode sheet or a negative electrode sheet.

[0111] In the embodiment of the present application, it does not matter whether the boundary (first boundary a) between the first segment 2211 and the second segment 2212 is located inside the winding start end 225b of the second electrode sheet 222 or whether the boundary (first boundary a) between the first segment 2211 and the second segment 2212 is located outside the winding start end 225b of the second electrode sheet 222. The winding start end 225a of the first electrode sheet 221 may be located in the straight region 224 or in the curved region 223, and the winding start end 225b of the second electrode sheet 222 may be located in the straight region 224 or in the curved region 223.

[0112] In the present embodiment, at least a portion of the first segment 2211 of the first electrode sheet 221 is used to provide support to the portions of the first electrode sheet 221 and the second electrode sheet 222 located outside the first segment 2211 in the bending region 223, and the first segment 2211 may support the electrode sheets outside the first segment 2211 in only one bending region 223, or the first segment 2211 may support the electrode sheets in two bending regions 223, which depends on the length of the first segment 2211.

[0113] In some embodiments, the length of the first segment 2211 may be L1, the length of the first sub-segment 2212a may be L2, and the relationship between L1 and L2 may be 3 mm≦L1≦6*L2.

[0114] 5 , in some embodiments, the first segment 2211 extends from the boundary (first boundary a) with the second segment 2212 in a spiral manner inward, bypassing one bend region 223. That is, the first segment 2211 supports the electrode sheet in only one bend region 223, and the first segment 2211 includes only one bend 2211 a. The first segment 2211 in this structure is short, saving material and reducing costs.

[0115] Optionally, both the winding start end 225a of the first electrode sheet 221 and the winding start end 225b of the second electrode sheet 222 are located within the straight region 224. The portion of the first electrode sheet 221 extending from the winding start end 225a of the first electrode sheet 221 to one of the bent regions 223 and the portion of the second electrode sheet 222 extending from the winding start end 225b of the second electrode sheet 222 to the other bent region 223 are offset from each other in the second direction C. The second direction C is perpendicular to the first direction B and the straight region 224. This structure effectively reduces the difference in thickness between both sides of the winding structure in the first direction B, ensures consistency in thickness between both sides of the winding structure in the first direction B, and improves the energy density of the electrode assembly 22.

[0116] The second direction C is perpendicular to the linear region 224, which may also be understood as the second direction C being perpendicular to the portions of the first electrode sheet 221 and the second electrode sheet 222 in the linear region 224, the second direction C being the thickness direction of the wound structure, and the second direction C being also the thickness direction of the portions of the first electrode sheet 221 and the second electrode sheet 222 in the linear region 224.

[0117] The portion of the first electrode sheet 221 extending from the winding start end 225a of the first electrode sheet 221 to one of the bending regions 223 is the first portion 2211b, which is located in the straight region 224, the first portion 2211b borders the bending portion 2211a, and the boundary between the first portion 2211b and the bending portion 2211a is located at the boundary between the straight region 224 and the bending region 223, and the portion of the second electrode sheet 222 extending from the winding start end 225a of the second electrode sheet 222 to the other bending region 223 is the second portion 2221, which is located in the straight region 224.

[0118] For example, the relationship that L1 and L2 satisfy may be 3 mm≦L1<0.75*L2.

[0119] 15 is a structural schematic diagram of an electrode assembly 22 provided according to some other embodiments of the present application. A portion of the first electrode sheet 221 extending from the winding start end 225a of the first electrode sheet 221 to one of the bent regions 223 and a portion of the second electrode sheet 222 extending from the winding start end 225b of the second electrode sheet 222 to the other of the bent regions 223 at least partially overlap in the second direction C, i.e., the first portion 2211b and the second portion 2221 at least partially overlap, where "at least partially overlapping" means that a projection of the first portion 2211b in the second direction C and a projection of the second portion 2221 in the second direction C at least partially overlap.

[0120] 16 and 17, in some embodiments, Fig. 16 is a structural schematic diagram of an electrode assembly 22 provided according to some other embodiments of the present application. Fig. 17 is a structural schematic diagram of an electrode assembly 22 provided according to yet another embodiment of the present application. The first segment 2211 extends while winding inward from the boundary (first boundary a) with the second segment 2212 and bypasses the two bent regions 223. That is, the first segment 2211 can support the electrode sheets in the two bent regions 223 and can provide support force to the portions of the first electrode sheet 221 and the second electrode sheet 222 in the two bent regions 223. This makes the structure of the portions of the first electrode sheet 221 and the second electrode sheet 222 in the two bent regions 223 more compact and reduces the occurrence of lithium deposition.

[0121] In this embodiment, the first segment 2211 includes a plurality of bent portions 2211a, some of which are located in one bent region 223, and other parts of which are located in the other bent region 223.

[0122] In one non-limiting example, as shown in FIG. 16, the first segment 2211 includes two bent portions 2211a, and the two bent portions 2211a are located in two bent regions 223, respectively.

[0123] For example, the relationship satisfied by L1 and L2 may be 0.75*L2≦L1<1.25*L2.

[0124] In another non-limiting example, as shown in FIG. 17, the first segment 2211 includes three bends 2211a, one bend 2211a located in one bend region 223 and the other two bends 2211a located in the other bend region 223.

[0125] For example, the relationship that L1 and L2 satisfy may be 1.25*L2≦L1≦6*L2.

[0126] 18, which is a flowchart of a method for manufacturing an electrode assembly 22 provided by some embodiments of the present application. The method for manufacturing an electrode assembly 22 includes the following steps.

[0127] In S100, a first electrode sheet 221 and a second electrode sheet 222 are provided.

[0128] In S200, the first electrode sheet 221 and the second electrode sheet 222 are wound along a winding direction A to form a wound structure, and the wound structure includes a bent region 223.

[0129] Here, the first electrode sheet 221 includes a first segment 2211 that extends beyond the winding starting end 225a of the first electrode sheet 221, and at least a portion of the first segment 2211 is used to provide support to the portions of the first electrode sheet 221 and the second electrode sheet 222 in the bending region 223 that are located outside the first segment 2211.

[0130] In some embodiments, a separator 227 is further provided to separate the first electrode sheet 221 and the second electrode sheet 222, and the first electrode sheet 221, the separator 227, and the second electrode sheet 222 are wound along the winding direction A to form a wound structure.

[0131] For the related structure of the electrode assembly 22 manufactured by the manufacturing method of the electrode assembly 22, reference can be made to the electrode assembly 22 provided in each of the above embodiments.

[0132] 19, which is a schematic block diagram of a manufacturing device 2000 for an electrode assembly 22 provided according to some embodiments of the present application. The electrode assembly 22 includes a first providing device 2100, a second providing device 2200, and an assembling device 2300.

[0133] The first providing device 2100 is used to provide a first electrode sheet 221. The second providing device 2200 is used to provide a second electrode sheet 222. The assembling device 2300 is used to wind the first electrode sheet 221 and the second electrode sheet 222 along a winding direction A to form a wound structure, and the wound structure includes a bending region 223.

[0134] Here, the first electrode sheet 221 includes a first segment 2211 that extends beyond the winding starting end 225a of the first electrode sheet 221, and at least a portion of the first segment 2211 is used to provide support to the portions of the first electrode sheet 221 and the second electrode sheet 222 in the bending region 223 that are located outside the first segment 2211.

[0135] In some embodiments, the manufacturing device 2000 for the electrode assembly 22 further includes a third providing apparatus (not shown), which is used to provide a separator 227 for isolating the first electrode sheet 221 and the second electrode sheet 222, and the assembling apparatus 2300 is used to wind the first electrode sheet 221, the separator 227 and the second electrode sheet 222 along the winding direction A to form a wound structure.

[0136] For the related art of the electrode assembly 22 manufactured by the manufacturing device 2000 for the electrode assembly 22, reference can be made to the electrode assemblies 22 provided in the above-mentioned embodiments.

[0137] It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other if they do not conflict.

[0138] The above embodiments are only used to explain the technical solution of the present application and are not intended to limit the present application, and those skilled in the art can make various modifications and variations to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application. [Explanation of symbols]

[0139] 10-Enclosure 11- Storage area 12-Cover part 13- Closed space 20-Battery Cells 21-Case 211-Case body 212-Cover body 213-Sealed Chamber 22-electrode assembly 221-First electrode sheet 2211-1st segment 2211a-bend 2211b-Part 1 2212-Second segment 2212a - 1st subsegment 2212b - Second subsegment 2212c - 3rd subsegment 2212d - 4th subsegment 222-Second electrode sheet 2221-Second part 223-bending area 224-Line area 225a, 225b - winding start end 226a, 226b—winding end 227-Separator 228-Negative electrode active material layer 229-Cathode active material layer 30-Battery Module 31-Bus parts 100-battery 200-Controller 300-Motor 1000-Vehicle 2000-manufacturing devices 2100-1st providing device 2200-Second providing device 2300-Assembly Equipment A-winding direction B - 1st direction C-Second direction a-first boundary b - second boundary c - third boundary d-The Fourth Realm

Claims

1. An electrode assembly applicable to a lithium ion secondary battery, comprising: a first electrode sheet and a second electrode sheet, the first electrode sheet and the second electrode sheet being wound along a winding direction to form a wound structure, the wound structure including a curved region, the first electrode sheet includes a first segment that extends beyond a winding start end of the second electrode sheet, and at least a portion of the first segment is used to provide support to portions of the first electrode sheet and the second electrode sheet that are located outside the first segment in the bending region; the first electrode sheet further includes a second segment disposed continuously with the first segment along the winding direction, the electrode assembly further includes a separator for separating the first electrode sheet and the second electrode sheet, the separator including a first separator and a second separator, the first separator, the first electrode sheet, the second separator, and the second electrode sheet being sequentially stacked and wound along the winding direction to form the wound structure; an electrode assembly, wherein the second separator extends beyond the winding start end of the first electrode sheet, and the portion of the second separator extending beyond the winding start end of the first electrode sheet is wound toward the inside of the first segment;

2. the boundary between the first segment and the second segment is located inside a winding start end of the second electrode sheet, The electrode assembly of claim 1 , wherein at least a portion of the first segment is supported inside the second segment at the bending region.

3. The electrode assembly of claim 2 , wherein a portion of the first segment in the bent region is supported inside the second segment by the separator.

4. the second segment includes a first sub-segment arranged contiguously with the first segment along the winding direction, Only one surface of the first sub-segment faces the active material layer of the second electrode sheet, and the first sub-segment is wound one turn from the boundary toward the outside along the winding direction, The electrode assembly according to claim 2 or 3, wherein the first segment includes a bent portion disposed bent in the bent region, the bent portion being supported by the first sub-segment in the bent region.

5. 5. The electrode assembly according to claim 4, wherein an active material layer is applied to both surfaces of the first sub-segment, or an active material layer is applied to a surface of the first sub-segment facing the active material layer of the second electrode sheet, and no active material layer is applied to the other surface of the first sub-segment.

6. the second segment further includes a second sub-segment and a third sub-segment; the first segment, the first sub-segment, the second sub-segment, and the third sub-segment are arranged in sequence along the winding direction, both surfaces of the second sub-segment face the active material layer of the second electrode sheet, the third sub-segment has only one surface facing the active material layer of the second electrode sheet; 6. The electrode assembly according to claim 4 or 5, wherein an active material layer is applied to both surfaces of the third sub-segment, or an active material layer is applied to the surface of the third sub-segment facing the active material layer of the second electrode sheet, and no active material layer is applied to the other surface of the third sub-segment.

7. the second segment further includes a fourth sub-segment; the first segment, the first sub-segment, the second sub-segment, the third sub-segment, and the fourth sub-segment are arranged in sequence along the winding direction, neither of the two surfaces of the fourth sub-segment faces the active material layer of the second electrode sheet; 7. The electrode assembly of claim 6, wherein an active material layer is applied to both surfaces of the fourth subsegment, or an active material layer is applied to an inner surface of the fourth subsegment, and no active material layer is applied to the other surface of the fourth subsegment.

8. the winding structure further includes a linear region, and the curved region is provided at both ends of the linear region; The electrode assembly according to any one of claims 2 to 7, wherein the winding start end of the first electrode sheet is located within the linear region, and / or the winding start end of the second electrode sheet is located within the linear region.

9. The electrode assembly of claim 8 , wherein the first segment extends from the boundary in a spiral inward direction, bypassing one of the bend regions.

10. Both the winding start end of the first electrode sheet and the winding start end of the second electrode sheet are located in the linear region, the two curved regions are located at both ends of the linear region in the first direction, a portion of the first electrode sheet extending from the winding start end of the first electrode sheet to one of the bent regions and a portion of the second electrode sheet extending from the winding start end of the second electrode sheet to the other bent region are offset from each other in a second direction; The electrode assembly of claim 9 , wherein the second direction is perpendicular to the first direction and the linear region.

11. The electrode assembly of claim 8 , wherein the first segment extends from the boundary in a spiral inward direction, bypassing two of the bend regions.

12. The electrode assembly according to any one of claims 1 to 9, wherein the first electrode sheet is a negative electrode sheet and the second electrode sheet is a positive electrode sheet.

13. The electrode assembly according to claim 12 , wherein both surfaces of the first segment are coated with a negative electrode active material layer.

14. A battery cell, a case and the electrode assembly according to any one of claims 1 to 13, The electrode assembly is housed in the case.

15. A battery, A battery cell according to claim 14, The battery cell is housed within the housing.

16. 16. An electrical device comprising the battery of claim 15.

17. A method for manufacturing an electrode assembly applied to a lithium ion secondary battery, comprising: providing a first electrode sheet, a second electrode sheet, and a separator for separating the first electrode sheet and the second electrode sheet, the separator including a first separator and a second separator; forming a wound structure by sequentially stacking the first separator, the first electrode sheet, the second separator, and the second electrode sheet and winding them along a winding direction, the wound structure including a bending region; wherein the first electrode sheet includes a first segment that extends beyond the winding start end of the second electrode sheet, and at least a portion of the first segment is used to provide a support force to portions of the first electrode sheet and the second electrode sheet that are located outside the first segment in the bending region; the first electrode sheet further includes a second segment disposed continuously with the first segment along the winding direction, The second separator extends beyond the winding start end of the first electrode sheet, and the second separator extends beyond the winding start end of the first electrode sheet. The portion to be wound is wound toward the inside of the first segment.

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