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

Abstract

The embodiment of the application provides an electrode assembly (22), a battery monomer (20), a battery (100) and a method and equipment (2000) for manufacturing the electrode assembly (22), and belongs to the technical field of batteries, comprising a first pole piece (221) and a second pole piece (222), the first pole piece (221) and the second pole piece (222) are wound along a winding direction (A) and form a winding structure, and the winding structure comprises a bending area (223). The first pole piece (221) comprises a first section (2211) beyond a winding starting end (225b) of the second pole piece (222), at least a part of the first section (2211) is used for providing a supporting force for the first pole piece (221) and the second pole piece (222) in the bending area (223) and located on the outside of the first section (2211), so that the first pole piece (221) and the second pole piece (222) are more compact in the bending area (223), a gap between the part of the first pole piece (221) in the bending area (223) and the part of the second pole piece (222) in the bending area (223) is not easy to increase due to the action of external force, and the occurrence of lithium precipitation is reduced.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to an electrode assembly, a battery cell, a battery, and a method and apparatus for manufacturing the electrode assembly. Background Technology

[0002] Currently, the most commonly used batteries in vehicles are lithium-ion batteries. As a rechargeable battery, lithium-ion batteries have advantages such as small size, high energy density, high power density, many cycles, and long storage time.

[0003] A rechargeable battery consists of an electrode assembly and an electrolyte. The electrode assembly comprises a second electrode, a first electrode, and a separator. Rechargeable batteries primarily function by the movement of metal ions between the second and first electrodes.

[0004] Lithium plating is a common abnormal phenomenon in lithium batteries. It occurs due to various anomalies, such as insufficient lithium intercalation space at the negative electrode, excessive resistance to lithium ion migration, or lithium ions rapidly detaching from the positive electrode but failing to intercalate into the negative electrode in equal quantities. As a result, lithium ions that cannot intercalate into the negative electrode can only gain electrons on the surface of the negative electrode, thus forming elemental lithium. Lithium plating affects the charging efficiency and energy density of lithium-ion batteries. In severe cases, lithium crystals can form, which can puncture the separator, leading to internal short circuits and thermal runaway, seriously endangering battery safety.

[0005] Therefore, how to reduce lithium plating is a technical problem that urgently needs to be solved in battery technology. Summary of the Invention

[0006] This application provides an electrode assembly, a battery cell, a battery, and a method and apparatus for manufacturing the electrode assembly, which can effectively reduce the occurrence of lithium plating.

[0007] In a first aspect, embodiments of this application provide an electrode assembly including a first electrode and a second electrode, the first electrode and the second electrode being wound along a winding direction to form a winding structure, the winding structure including a bending region; the first electrode includes a first segment extending beyond the winding start end of the second electrode, at least a portion of the first segment being used to provide support force to the portions of the first electrode and the second electrode located in the bending region and outside the first segment.

[0008] In the above scheme, the first electrode includes a first segment that extends beyond the starting end of the winding of the second electrode. The first segment can provide support for the portion of the first electrode and the second electrode in the bending area and located outside the first segment, making the structure of the portion of the first electrode and the second electrode in the bending area more compact. The gap between the portion of the first electrode and the portion of the second electrode in the bending area is less likely to increase due to external forces, thereby reducing the occurrence of lithium plating.

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

[0010] In the above scheme, the junction of the first segment and the second segment is located inside the winding start end of the second electrode. The part of the first segment in the bending area can be supported on the inside of the second segment. The supporting force provided by the part of the first segment in the bending area can be transferred to the second segment first, and then transferred to the second electrode through the second segment, so that the first segment provides better support for the part of the first electrode in the bending area and the part of the second electrode in the bending area.

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

[0012] In the above scheme, the separator membrane serves to isolate the first electrode and the second electrode, reducing the risk of a short circuit between them. The portion of the first segment located in the bending area is supported on the inside of the second segment by the separator membrane. The supporting force provided by the portion of the first segment in the bending area can be transferred to the second segment through the separator membrane, which isolates the portions of the first and second segments in the bending area.

[0013] In some embodiments, the second segment includes a first sub-segment continuously arranged with the first segment along the winding direction; the first sub-segment faces the active material layer of the second electrode sheet on only one side, and the first sub-segment is wound outward from the junction along the winding direction once; the first segment includes a bent portion arranged in the bent area, the bent portion being supported by the first sub-segment within the bent area.

[0014] In the above scheme, the bent part of the first segment is supported by the first sub-segment in the bending area. The bent part is in a bent state in the bending area, which can produce a good support effect on the first sub-segment.

[0015] In some embodiments, both sides of the first sub-segment are coated with an active material layer; or the side of the first sub-segment opposite to the active material layer of the second electrode is coated with an active material layer, and the other side of the first sub-segment is not coated with an active material layer.

[0016] In the above scheme, both sides of the first segment can be coated with an active material layer, which can simplify the production process of the first electrode and facilitate the forming of the first electrode; or the side of the first segment opposite to the active material layer of the second electrode can be coated with an active material layer, while the other side of the first segment is not coated with an active material layer, which reduces the amount of active material layer used on the first electrode and lowers the production cost of the first electrode.

[0017] In some embodiments, 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 sequentially and continuously along the winding direction; both sides of the second sub-segment are opposite to the active material layer of the second electrode; the third sub-segment is opposite to the active material layer of the second electrode on only one side; wherein, both sides of the third sub-segment are coated with an active material layer; or the side of the third sub-segment opposite to the active material layer of the second electrode is coated with an active material layer, and the other side of the third sub-segment is not coated with an active material layer.

[0018] In the above scheme, the third segment only faces the active material layer of the second electrode on one side. It can be that both sides of the third segment are coated with the active material layer, which can simplify the production process of the first electrode and facilitate the forming of the first electrode; or the third segment can be coated with the active material layer on the side facing the active material layer of the second electrode, while the other side of the third segment is not coated with the active material layer, which reduces the amount of active material layer used on the first electrode and lowers the production cost of the first electrode.

[0019] In some embodiments, 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 sequentially and continuously along the winding direction; neither side of the fourth sub-segment is opposite to the active material layer of the second electrode; both sides of the fourth sub-segment are coated with an active material layer, or the inner side of the fourth sub-segment is coated with an active material layer, and the other side of the fourth sub-segment is not coated with an active material layer.

[0020] In the above scheme, neither side of the fourth sub-segment is opposite to the active material layer of the second electrode. It can be that both sides of the fourth sub-segment are coated with the active material layer, which can simplify the production process of the first electrode and facilitate the forming of the first electrode; or it can be that the side of the fourth sub-segment located on its inner side is coated with the active material layer, while the other side of the fourth sub-segment is not coated with the active material layer, which reduces the amount of active material layer used on the first electrode and lowers the production cost of the first electrode.

[0021] In some embodiments, the winding structure further includes a flat region, with the bending region provided at both ends of the flat region; the winding start end of the first electrode is located within the flat region; and / or, the winding start end of the second electrode is located within the flat region.

[0022] In the above scheme, the starting end of the winding of the first electrode can be located in the flat region, and the starting end of the winding of the second electrode can also be located in the flat region, so as to facilitate the winding of the first electrode and the second electrode.

[0023] In some embodiments, the first segment extends inward from the junction and around one of the bends.

[0024] In the above scheme, the first segment extends inward from its junction with the second segment and bypasses a bending zone, meaning the first segment provides support for the portions of the first and second electrodes located within this bending zone. This structure results in a shorter first segment, saving materials and reducing costs.

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

[0026] In the above scheme, the portion of the first electrode extending from the winding start end to a bend area and the portion of the second electrode extending from the winding start end to another bend area are staggered in the second direction. This structure can effectively reduce the thickness difference between the two sides of the winding structure in the first direction, ensure the consistency of the thickness of the winding structure on both sides in the first direction, and improve the energy density of the electrode assembly.

[0027] In some embodiments, the first segment extends inward from the junction and bypasses the two bending areas.

[0028] In the above scheme, the first segment extends inward from the junction with the second segment and bypasses the two bending areas. That is, the first segment can provide support for the parts of the first and second electrodes located in the two bending areas, making the structure of the first and second electrodes in the two bending areas more compact and reducing the occurrence of lithium plating.

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

[0030] In the above scheme, the first electrode and the second electrode are the negative electrode and the positive electrode, respectively. Since the first section of the first electrode extends beyond the winding start of the second electrode, and the second electrode has no corresponding part to the first section, the first section is the non-lithium-intercalated part of the first electrode, making lithium plating less likely to occur in the first section. Furthermore, the portion of the first electrode in the bending area and located outside the first section can be supported by the first section, increasing the radius of curvature of this portion. This reduces the risk of lithium plating caused by the innermost ring of the lithium-intercalated portion of the first electrode shedding powder (active material layer shedding) in the bending area due to the small radius of curvature.

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

[0032] In the above scheme, both sides of the first segment are coated with a negative electrode active material layer, which makes the overall thickness of the first segment thicker and improves the support capacity of the first segment.

[0033] Secondly, embodiments of this application provide a battery cell, including a casing and an electrode assembly provided in any one of the embodiments of the first aspect;

[0034] The electrode assembly is housed within the housing.

[0035] In the above scheme, the first segment of the first electrode in the electrode assembly can provide support for the portion of the first electrode and the second electrode in the bending area and located outside the first segment, making the structure of the first electrode and the second electrode in the bending area more compact. The gap between the portion of the first electrode in the bending area and the portion of the second electrode in the bending area is less likely to increase due to external force, reducing the occurrence of lithium plating, improving the safety of the battery cell, and extending the service life of the battery cell.

[0036] Thirdly, embodiments of this application provide a battery, including a housing and a battery cell provided in any of the second aspects of the embodiments, wherein the battery cell is housed within the housing.

[0037] Fourthly, embodiments of this application provide an electrical device including the battery provided in any one of the embodiments of the third aspect.

[0038] Fifthly, embodiments of this application provide a method for manufacturing an electrode assembly, comprising:

[0039] A first electrode and a second electrode are provided; the first electrode and the second electrode are wound along a winding direction to form a winding structure, the winding structure including a bending region; wherein the first electrode includes a first segment extending beyond the winding start end of the first electrode, at least a portion of the first segment is used to provide support force to the portions of the first electrode and the second electrode in the bending region and located outside the first segment.

[0040] In a sixth aspect, embodiments of this application provide an electrode assembly manufacturing apparatus, including a first providing device, a second providing device, and an assembly device; the first providing device is used to provide a first electrode sheet; the second providing device is used to provide a second electrode sheet; the assembly device is used to wind the first electrode sheet and the second electrode sheet along a winding direction to form a winding structure, the winding structure including a bending region; wherein, the first electrode sheet includes a first segment extending beyond the winding start end of the first electrode sheet, at least a portion of the first segment is used to provide support force to the portion of the first electrode sheet and the second electrode sheet located in the bending region and outside the first segment. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0042] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0043] Figure 2 This application provides schematic diagrams of the battery structure for some embodiments.

[0044] Figure 3 for Figure 2 The diagram shows the structure of the battery module of the battery shown.

[0045] Figure 4 for Figure 3 An exploded view of a single battery cell in the battery module shown.

[0046] Figure 5 This is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application;

[0047] Figure 6 for Figure 5 The diagram shows the unfolded structure of the electrode assembly.

[0048] Figure 7 for Figure 5 A partially enlarged view of the first segment of the first electrode plate shown;

[0049] Figure 8 for Figure 5 A partially enlarged view of the first sub-segment and the second electrode of the first electrode shown;

[0050] Figure 9 A partially enlarged view of the first sub-segment and the second electrode of the first electrode provided in some embodiments of this application;

[0051] Figure 10 for Figure 5 A partially enlarged view of the third sub-segment of the first electrode and the second electrode plate shown;

[0052] Figure 11 A partially enlarged view of the third sub-segment of the first electrode and the second electrode plate provided for some embodiments of this application;

[0053] Figure 12 for Figure 5 A partially enlarged view of the fourth sub-segment of the first electrode and the second electrode plate shown;

[0054] Figure 13 A partially enlarged view of the fourth sub-segment of the first electrode and the second electrode plate provided for some embodiments of this application;

[0055] Figure 14 This application provides schematic diagrams of the structure of electrode assemblies in some of its embodiments.

[0056] Figure 15 This is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application;

[0057] Figure 16 This is a schematic diagram of the structure of an electrode assembly provided in other embodiments of this application;

[0058] Figure 17 This is a schematic diagram of the structure of an electrode assembly provided in some other embodiments of this application;

[0059] Figure 18 A flowchart illustrating a method for manufacturing an electrode assembly provided in some embodiments of this application;

[0060] Figure 19 A schematic block diagram of an electrode assembly manufacturing apparatus provided for some embodiments of this application;

[0061] The accompanying drawings are not drawn to scale.

[0062] Marking Explanation: 10-Box body; 11-Containing part; 12-Covering part; 13-Sealed space; 20-Battery cell; 21-Outer shell; 211-Shell; 212-Cover body; 213-Sealed chamber; 22-Electrode assembly; 221-First electrode; 2211-First segment; 2211a-Bending part; 2211b-First part; 2212-Second segment; 2212a-First sub-segment; 2212b-Second sub-segment; 2212c-Third sub-segment; 2212d-Fourth sub-segment; 222-Second electrode; 2221-Second part; 223-Bending area; 224-Straight area; 225a, 225b - Winding start end; 226a, 226b - Winding end; 227 - Separator; 228 - Negative electrode active material layer; 229 - Positive electrode active material layer; 30 - Battery module; 31 - Busbar component; 100 - Battery; 200 - Controller; 300 - Motor; 1000 - Vehicle; 2000 - Manufacturing equipment; 2100 - First supply device; 2200 - Second supply device; 2300 - Assembly device; A - Winding direction; B - First direction; C - Second direction; a - First junction; b - Second junction; c - Third junction; d - Fourth junction. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0064] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0065] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0066] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0067] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0068] In this application, "multiple" means two or more (including two).

[0069] In this application, the battery cell may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application are not limited to these. The battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited to these. Battery cells are generally divided into three types according to their packaging method: cylindrical battery cells, cuboid / square battery cells, and pouch battery cells, and the embodiments of this application are not limited to these.

[0070] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack. A battery generally includes a housing for encapsulating one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0071] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrodes. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the uncoated positive current collector protrudes beyond the coated one, serving as the positive electrode tab. Taking a lithium-ion battery as an example, the positive current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the uncoated negative current collector protrudes beyond the coated one, serving as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. To ensure that a large current can pass through without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together. The separator can be made of PP (polypropylene) or PE (polyethylene), etc.

[0072] In lithium-ion batteries, during charging, lithium ions are extracted from the positive electrode and inserted into the negative electrode; during discharging, lithium ions are extracted from the negative electrode and inserted into the positive electrode. During charging, some abnormal situations may occur that lead to lithium plating. These abnormalities include insufficient lithium insertion space in the negative electrode, excessive resistance to lithium ion migration, and lithium ions detaching too quickly from the positive electrode but not being able to insert an equal amount into the negative electrode. Lithium ions that cannot be inserted into the negative electrode can only gain electrons on the surface of the negative electrode, thus forming elemental lithium, a phenomenon known as lithium plating.

[0073] The inventors discovered that lithium plating is prone to occur in the bending area of ​​the electrode assembly. Further research revealed that after the first and second electrodes are wound into a winding structure using a winding needle, the electrodes in contact with the winding needle are displaced under the influence of the winding needle during the pulling out of the winding needle. This increases the gap between the portion of the first electrode in the bending area and the portion of the second electrode in the bending area, making lithium plating more likely to occur during charging.

[0074] In view of this, the present application provides a technical solution in which the first section of the first electrode extends beyond the starting end of the second electrode winding to provide support for the portions of the first and second electrodes in the bending area and located outside the first section. This makes the structure of the portions of the first and second electrodes in the bending area more compact, and the gap between the portions of the first and second electrodes in the bending area is less likely to increase due to external forces, thereby reducing the occurrence of lithium plating.

[0075] The technical solutions described in the embodiments of this application are applicable to batteries and electrical devices that use batteries.

[0076] The electrical equipment provided in this application embodiment can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc.; spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application embodiment does not impose any special limitations on the above-mentioned electrical equipment.

[0077] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0078] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. A battery 100 is disposed inside the vehicle 1000, and the battery 100 may be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source for the vehicle 1000.

[0079] The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, for the power needs of the vehicle 1000 during startup, navigation and driving.

[0080] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0081] Please refer to Figure 2 , Figure 2 This is an exploded view of a battery 100 provided in some embodiments of this application. The battery 100 provided in the embodiments of this application includes a housing 10 and a battery cell 20. Figure 2 (Not shown), the battery cell 20 is housed inside the casing 10.

[0082] The housing 10 is used to house the battery cell 20, providing a sealed environment for the battery cell 20. In some embodiments, the housing 10 may include a receiving portion 11 and a covering portion 12, with the receiving portion 11 covering the covering portion 12, and the receiving portion 11 and the covering portion 12 together defining a sealed space 13 for housing the battery cell 20. The receiving portion 11 and the covering portion 12 may both be hollow structures with an opening on one side, and the opening side of the receiving portion 11 covers the opening side of the covering portion 12, thus forming a housing 10 with a sealed space 13. Of course, the receiving portion 11 and the covering portion 12 may be of various shapes, such as cylinders, cuboids, etc.

[0083] In battery 100, there can be one or more battery cells 20. If there are multiple battery cells 20, they can be connected in series, in parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel. Multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed manner, and then the whole assembly of multiple battery cells 20 is housed in the housing 10. Alternatively, multiple battery cells 20 can first be connected in series, in parallel, or in a mixed manner to form a battery module 30, and then multiple battery modules 30 can be connected in series, in parallel, or in a mixed manner to form a whole assembly, which is then housed in the housing 10.

[0084] In some embodiments, please refer to Figure 3 , Figure 3 for Figure 2 The diagram shows the structure of the battery module 30 of the battery 100. Multiple battery cells 20 are connected in series, parallel, or a combination thereof to form the battery module 30. These battery modules 30 are then connected in series, parallel, or a combination thereof to form a whole, which is housed within the casing 10.

[0085] In some embodiments, multiple battery cells 20 in the battery module 30 can be electrically connected through a busbar 31 to achieve parallel, series, or mixed connection of multiple battery cells 20 in the battery module 30.

[0086] Please refer to Figure 4 , Figure 4 for Figure 3 The image shows an exploded view of the battery cell 20 of the battery module 30. The battery cell 20 provided in this embodiment includes a housing 21 and an electrode assembly 22, which is housed within the housing 21.

[0087] The housing 21 provides a sealed environment for the electrode assembly 22, and the housing 21 is filled with an electrolyte, such as an electrolyte solution.

[0088] It should be noted that in the battery cell 20, the electrode assembly 22 housed within the casing 21 can be one or more. For example, in... Figure 4In the middle, there are two electrode components 22.

[0089] In some embodiments, please continue to refer to Figure 4 The outer casing 21 may include a housing 211 and a cover 212. The housing 211 is a hollow structure with an opening on one side. The cover 212 closes onto the opening of the housing 211 to form a sealed connection, thereby forming a sealed chamber 213 for accommodating the electrode assembly 22 and the electrolyte. When assembling the battery cell 20, the electrode assembly 22 can be placed into the housing 211 first, and the electrolyte can be filled into the housing 211. Then, the cover 212 is closed onto the opening of the housing 211.

[0090] The housing 211 can have various shapes, such as a cylinder or a cuboid. The shape of the housing 211 can be determined based on the specific shape of the electrode assembly 22. For example, if the electrode assembly 22 has a cylindrical structure, the housing 211 can be a cylindrical shell 21; if the electrode assembly 22 has a cuboid structure, the housing 211 can be a cuboid shell 21. Of course, the cover 212 can also have various structures, such as a plate-like structure or a hollow structure with one open end. For example, in… Figure 4 In the case, the shell 211 has a cuboid structure, and the cover 212 has a plate-like structure, with the cover 212 covering the opening at the top of the shell 211.

[0091] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the structure of an electrode assembly 22 provided in some embodiments of this application. The electrode assembly 22 provided in the embodiments of this application includes a first electrode 221 and a second electrode 222. The first electrode 221 and the second electrode 222 are wound along the winding direction A to form a winding structure, and the winding structure includes a bending region 223. The first electrode 221 includes a first segment 2211 that extends beyond the winding start end 225b of the second electrode 222. At least a portion of the first segment 2211 is used to provide support for the portions of the first electrode 221 and the second electrode 222 in the bending region 223 and located outside the first segment 2211.

[0092] The first segment 2211 can provide support for the portion of the first electrode 221 and the second electrode 222 in the bending region 223 and located outside the first segment 2211, making the structure of the first electrode 221 and the second electrode 222 in the bending region 223 more compact. The gap between the portion of the first electrode 221 in the bending region 223 and the portion of the second electrode 222 in the bending region 223 is not easily increased by external force, and the electrode in contact with the winding needle is not easily displaced during the process of pulling out the winding needle, thus reducing the occurrence of lithium plating.

[0093] It should be noted that the winding direction A is the direction in which the first electrode 221 and the second electrode 222 are wound circumferentially from their winding starting end 225b outwards. Figure 5 In the middle, the clockwise direction is the winding direction A.

[0094] The first electrode 221 has two ends, namely a winding start end 225a and a winding end end 226a. The winding start end 225a of the first electrode 221 is the feed end of the first electrode 221, which is the free end of the first electrode 221 at its innermost circle. The winding end end 226a of the first electrode 221 is the free end of the first electrode 221 at its outermost circle. The second electrode 222 also has two ends, namely a winding start end 225b and a winding end end 226b. The winding start end 225b of the second electrode 222 is the feed end of the second electrode 222, which is the free end of the second electrode 222 at its innermost circle. The winding end end 226b of the second electrode 222 is the free end of the second electrode 222 at its outermost circle.

[0095] The winding structure also includes a straight region 224, with bent regions 223 at both ends. The two bent regions 223 are located at the two ends of the straight region 224 in the first direction B. The straight region 224 is the area of ​​the winding structure with a straight structure, where the portions of the first electrode 221 and the second electrode 222 located within the straight region 224 are generally arranged along the first direction B. The bent region 223 is the area of ​​the winding structure with a bent structure, where the portions of the first electrode 221 and the second electrode 222 located within the bent region 223 are both bent. For example, the portions of the first electrode 221 and the second electrode 222 located within the bent region 223 are arc-shaped.

[0096] The electrode assembly 22 may also include a separator 227 that isolates the first electrode 221 from the second electrode 222. The separator 227 has insulating properties, reducing the risk of a short circuit between the first electrode 221 and the second electrode 222. The separator 227 may be made of materials such as PP (polypropylene) or PE (polyethylene).

[0097] In some embodiments, please refer to Figure 6 , Figure 6 for Figure 5 The diagram shows the unfolded structure of the electrode assembly 22. The electrode assembly 22 may include two insulating films 227, one insulating film 227, a first electrode 221, another insulating film 227, and a second electrode 222, which are stacked sequentially. After stacking, the four components are arranged along the winding direction A (see [reference]). Figure 5 Winding can form a wound structure.

[0098] In this embodiment, the first electrode 221 and the second electrode 222 have opposite polarities. The first electrode 221 can be a negative electrode and the second electrode 222 a positive electrode; alternatively, the first electrode 221 can be a positive electrode and the second electrode 222 a negative electrode. If the first electrode 221 is a positive electrode and the second electrode 222 is a negative electrode, the first segment 2211 of the first electrode 221 may not be coated with the positive active material layer 229 on either side. That is, the first segment 2211 of the first electrode 221 only has a positive current collector and no positive active material layer 229, reducing the occurrence of lithium plating. If the first electrode 221 is a negative electrode and the second electrode 222 is a positive electrode, the first segment 2211 of the first electrode 221 may not be coated with the negative electrode active material layer 228 on both sides, or it may be coated with the negative electrode active material layer 228 on at least one side. That is to say, the first segment 2211 of the first electrode 221 may only have a negative electrode current collector, or it may include a negative electrode current collector and a negative electrode active material layer 228 coated on the negative electrode current collector.

[0099] In some embodiments, the first electrode 221 is the negative electrode, and the second electrode 222 is the positive electrode. Please refer to... Figure 7 , Figure 7 for Figure 5 The image shows a partial enlarged view of the first segment 2211 of the first electrode 221. Both sides of the first segment 2211 of the first electrode 221 are coated with a negative electrode active material layer 228, which makes the overall thickness of the first segment 2211 relatively thick and improves the support capacity of the first segment 2211.

[0100] For a typical electrode assembly 22, the innermost electrode in the bending region 223 typically has the greatest degree of bending, meaning that the innermost electrode in the bending region 223 has the smallest radius of curvature and the highest probability of powder shedding (shedding of the active material layer). If the innermost electrode is a negative electrode, there is a risk of lithium plating.

[0101] In this embodiment, since the first electrode 221 is the negative electrode, and the first segment 2211 of the first electrode 221 extends beyond the winding start end 225b of the second electrode 222, and at least a portion of the first segment 2211 is located within the bending region 223 to provide support to the first electrode 221 and the second electrode 222 on its outer side, the electrode at the innermost side of the electrode assembly 22 in the bending region 223 is the first segment 2211. The second electrode 222 has no part corresponding to the first segment 2211. The first segment 2211 is the part of the first electrode that does not have lithium intercalation. Even if the part of the first segment 2211 located within the bending region 223 is too small and causes powder shedding (shedding of the active material layer), lithium plating is not likely to occur. Furthermore, since the portion of the first electrode 221 located in the bending region 223 and outside the first segment 2211 can be supported by the first segment 2211, the radius of curvature of this portion increases, reducing the risk of lithium plating caused by the innermost ring of the lithium-intercalated portion of the first electrode 221 being decomposed (the active material layer falls off) in the bending region 223 due to the small radius of curvature.

[0102] In some embodiments, please continue to refer to Figure 5 The first electrode 221 also includes a second segment 2212 continuously arranged along the winding direction A and the first segment 2211. The junction of the first segment 2211 and the second segment 2212 (first junction a) is located inside the winding start end 225b of the second electrode 222. At least a portion of the first segment 2211 is supported inside the second segment 2212 in the bending region 223.

[0103] The supporting force provided by the first segment 2211 in the bending area 223 can be transferred to the second segment 2212 first, and then transferred to the second electrode 222 through the second segment 2212, so that the first segment 2211 provides better support for the first electrode 221 in the bending area 223 and the second electrode 222 in the bending area 223.

[0104] The second segment 2212 is the part of the first electrode 221 where lithium is inserted. During charging, lithium ions are de-intercalated from the second electrode 222 and inserted into the second segment 2212. During discharging, lithium ions are de-intercalated from the second segment 2212 and inserted into the second electrode 222.

[0105] For a typical electrode assembly 22, the starting end of the first electrode 221 is located in the flat region 224. After the first electrode 221, the second electrode 222, and the separator 227 are wound into a wound structure by a winding needle, there is friction between the winding needle and the first electrode 221. During the process of pulling out the winding core of the wound structure, the winding needle causes the part of the second segment 2212 located at the innermost side of the bending region 223 to be displaced, resulting in an increase in the gap between the part of the second segment 2212 located at the innermost side of the bending region 223 and the second electrode 222. During charging, lithium plating is likely to occur.

[0106] In this embodiment, at least a portion of the first segment 2211 is supported on the inner side of the second segment 2212 in the bending area 223. During the process of pulling out the coil needle, the coil needle is less likely to cause displacement of the innermost part of the second segment 2212 in the bending area 223, thereby reducing the occurrence of lithium plating.

[0107] It should be noted that at least a portion of the first segment 2211 is supported on the inside of the second segment 2212 in the bending area 223. This can be achieved by the portion of the first segment 2211 located in the bending area 223 directly contacting the second segment 2212 for support, or by the portion of the first segment 2211 located in the bending area 223 being supported on the inside of the second segment 2212 through the isolation membrane 227. The isolation membrane 227 can isolate the portion of the first segment 2211 located in the bending area 223 from the portion of the second segment 2212 located in the bending area 223. The portion of the first segment 2211 located in the bending area 223 is in contact with the isolation membrane 227, and the isolation membrane 227 is in contact with the second segment 2212. The supporting force provided by the portion of the first segment 2211 located in the bending area 223 can be transmitted to the second segment 2212 through the isolation membrane 227.

[0108] For example, in Figure 5 In the first segment 2211, the portion located in the bending region 223 is supported by the separator 227 on the inner side of the second segment 2212. The separator 227 extends beyond the winding start end 225a of the first electrode 221, and the portion of the separator 227 extending beyond the winding start end 225a of the first electrode 221 is wound towards the inner side of the first segment 2211.

[0109] In some embodiments, please continue to refer to Figure 5 The second segment 2212 includes a first sub-segment 2212a connected to the first segment 2211 along the winding direction A, i.e., the first sub-segment 2212a and the first segment 2211 meet at the junction. Only one side of the first sub-segment 2212a faces the active material layer of the second electrode 222. The first sub-segment 2212a is wound outwards one turn along the winding direction A from its junction with the first segment 2211. The first segment 2211 includes a bent portion 2211a arranged in the bending region 223, which supports the first sub-segment 2212a within the bending region 223. The bent portion 2211a is in a bent state within the bending region 223, providing excellent support for the first sub-segment 2212a.

[0110] The first junction a is the point where the first sub-segment 2212a and the first segment 2211 meet. The portion of the first segment 2211 located in the bending area 223 is the bending portion 2211a. For example, the bending portion 2211a is arc-shaped.

[0111] Since the first junction a is located inside the winding start end 225b of the second electrode 222, there is no second electrode 222 inside the first sub-segment 2212a. The first sub-segment 2212a only faces the active material layer of the second electrode 222 on one side. That is, the inner side of the first sub-segment 2212a does not face the active material layer of the second electrode 222, and the outer side of the first sub-segment 2212a faces the active material layer of the second electrode 222 located outside and adjacent to it.

[0112] The active material layer of the first sub-segment 2212a can have various configurations. For example, please refer to... Figure 8 , Figure 8 for Figure 5 The enlarged view of the first segment 2212a and the second electrode 222 of the first electrode shown indicates that both sides of the first segment 2212a are coated with an active material layer, which can be the negative electrode active material layer 228. This simplifies the manufacturing process of the first electrode 221 and facilitates its formation. Please refer to... Figure 9 , Figure 9 The partial enlarged view of the first segment 2212a and the second electrode 222 provided in some embodiments of this application may also show that the active material layer is coated on the side of the first segment 2212a opposite to the active material layer of the second electrode 222. The active material layer on the first segment 2212a may be a negative electrode active material layer 228, and the active material layer on the second electrode 222 may be a positive electrode active material layer 229. The other side of the first segment 2212a is not coated with an active material layer, which can reduce the amount of active material layer used on the first electrode 221 and reduce the production cost of the first electrode 221.

[0113] During the charging and discharging process, lithium is de-intercalated between the active material layer on the inner side of the first sub-segment 2212a and the active material layer of the second electrode 222.

[0114] For example, if the active material layer on the first electrode 221 is a negative active material layer 228, then the active material layer on the outer surface of the first sub-segment 2212a is a negative active material layer 228; the active material layer on the second electrode 222 is a positive active material layer 229. The second electrode 222 is coated with the positive active material layer 229 on both sides from its winding start end 225b to its winding end end 226b.

[0115] In some embodiments, please continue to refer to Figure 5The second segment 2212 may also 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 arranged sequentially along the winding direction A; both sides of the second sub-segment 2212b are opposite to the active material layer of the second electrode 222; the third sub-segment 2212c is opposite to the active material layer of the second electrode 222 on only one side.

[0116] The second sub-segment 2212b intersects with the first sub-segment 2212a, and the third sub-segment 2212c intersects with the second sub-segment 2212b. The intersection of the second sub-segment 2212b and the first sub-segment 2212a is the second intersection point b, and the intersection of the third sub-segment 2212c and the second sub-segment 2212b is the third intersection point c. Since the first sub-segment 2212a winds outward one turn along the winding direction A from its intersection with the first segment 2211, the second intersection point b is located outside the first intersection point a.

[0117] Both sides of the second sub-segment 2212b are coated with an active material layer. Both sides of the second sub-segment 2212b are opposite to the active material layer of the second electrode 222; that is, the active material layer coated on the inner side of the second sub-segment 2212b is opposite to the active material layer of the adjacent second electrode 222, and the active material layer coated on the outer side of the second sub-segment 2212b is opposite to the active material layer of the adjacent second electrode 222. During charging and discharging, lithium is intercalated / deintercalated between the active material layer coated on the inner side of the second sub-segment 2212b and the active material layer of the adjacent second electrode 222, and vice versa.

[0118] The third segment 2212c faces only one side of the active material layer of the second electrode 222; that is, the outer surface of the third segment 2212c does not face the active material layer of the second electrode 222, but faces the active material layer of the adjacent second electrode 222 located inside it. For example, as... Figure 5 As shown, the outer side of the third sub-segment 2212c does not have a second electrode 222, so that the outer surface of the third sub-segment 2212c is not opposite to the active material layer of the second electrode 222.

[0119] The active material layer of the third sub-segment 2212c can have various configurations. For example, please refer to... Figure 10 , Figure 10 for Figure 5 The enlarged view of the third segment 2212c of the first electrode and the second electrode plate 222 shown indicates that both sides of the third segment 2212c are coated with an active material layer, which may be the negative electrode active material layer 228; please refer to... Figure 11 , Figure 11 The partial enlarged view of the third segment 2212c of the first electrode and the second electrode 222 provided in some embodiments of this application may also show that the side of the third segment 2212c opposite to the active material layer of the second electrode 222 is coated with an active material layer. The active material layer on the third segment 2212c may be a negative electrode active material layer 228, and the active material layer on the second electrode 222 may be a positive electrode active material layer 229. The other side of the third segment 2212c is not coated with an active material layer.

[0120] In some embodiments, please continue to refer to Figure 5 The second segment 2212 may also include a fourth sub-segment 2212d. 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 along the winding direction A. Neither side of the fourth sub-segment 2212d is opposite to the active material layer of the second electrode 222.

[0121] Among them, the fourth sub-segment 2212d intersects with the third sub-segment 2212c, and the intersection of the fourth sub-segment 2212d and the third sub-segment 2212c is the fourth intersection point d.

[0122] Neither of the two sides of the fourth segment 2212d is opposite to the active material layer of the second electrode 222; that is, neither the inner nor outer side of the fourth segment 2212d is opposite to the active material layer of the second electrode 222. For example, the fourth segment 2212d extends beyond the winding end 226b of the second electrode 222, such that neither of the two sides of the fourth segment 2212d is opposite to the active material layer of the second electrode 222.

[0123] When the second electrode 222 is a negative electrode, a fourth sub-segment 2212d that extends beyond the winding end 226b of the second electrode 222 can be provided in the second electrode 222 to effectively reduce the occurrence of lithium plating at the end of the first electrode 221.

[0124] The active material layer of the fourth sub-segment 2212d can be configured in various ways. For example, please refer to... Figure 12 , Figure 12 for Figure 5 The enlarged view of the fourth segment 2212d of the first electrode and the second electrode plate 222 shown indicates that both sides of the fourth segment 2212d are coated with an active material layer, which may be the negative electrode active material layer 228; please refer to... Figure 13 , Figure 13The image shows a partial enlarged view of the fourth segment 2212d of the first electrode and the second electrode plate 222 provided in some embodiments of this application. The inner side of the fourth segment 2212d is coated with an active material layer, while the other side of the fourth segment 2212d is not coated with an active material layer. That is, the inner side of the fourth segment 2212d is coated with an active material layer, while the outer side of the fourth segment 2212d is not coated with an active material layer. The active material layer of the fourth segment 2212d may be a negative electrode active material layer 228.

[0125] The fourth segment 2212d is the terminal segment of the first electrode 221. The first electrode 221 can terminate at the bending region 223 or at the straight region 224; that is, the fourth segment 2212d can be located in either the bending region 223 or the straight region 224. For example, in... Figure 5 In the middle, the fourth sub-segment 2212d is located in the bending region 223.

[0126] The end of the fourth segment 2212d that is furthest from the third segment 2212c is the winding end 226a of the first electrode 221. The separator 227 can extend beyond the winding end 226a of the first electrode 221 and be wound a distance along the winding direction A.

[0127] For example, the length of the fourth sub-segment 2212d can range from 3mm to 15mm.

[0128] It should be noted that, as can be seen from the above embodiments, the junction of the first segment 2211 and the second segment 2212 (first junction a) can also be located inside the winding start end 225b of the second pole piece 222. In other embodiments, please refer to... Figure 14 , Figure 14 This is a schematic diagram of the structure of the electrode assembly 22 provided in some embodiments of this application. The junction of the first segment 2211 and the second segment 2212 (first junction a) may also be located outside the winding start end 225b of the second electrode 222. In this case, the first segment 2211 is at least partially supported on the inside of the second electrode 222 in the bending region 223.

[0129] It should be noted that the first segment 2211 is at least partially supported on the inner side of the second electrode 222 in the bending area 223. This can be because the portion of the first segment 2211 in the bending area 223 is in direct contact with the second electrode 222 to be supported on the inner side of the second electrode 222; or the portion of the first segment 2211 in the bending area 223 is supported on the inner side of the second electrode 222 by the isolation membrane 227. The isolation membrane 227 can isolate the first segment 2211 and the second electrode 222. The portion of the first segment 2211 in the bending area 223 is in contact with the isolation membrane 227, and the isolation membrane 227 is in contact with the second electrode 222 to achieve force transmission.

[0130] In this embodiment, the first electrode 221 can be either a positive electrode or a negative electrode.

[0131] In this embodiment, whether the junction of the first segment 2211 and the second segment 2212 (first junction a) is located inside the winding start end 225b of the second electrode 222, or the junction of the first segment 2211 and the second segment 2212 (first junction a) is located outside the winding start end 225b of the second electrode 222, the winding start end 225a of the first electrode 221 can be located within the straight region 224 or within the bending region 223; the winding start end 225b of the second electrode 222 can be located within the straight region 224 or within the bending region 223.

[0132] In the embodiments of this application, at least a portion of the first segment 2211 of the first electrode 221 is used to provide support for the portion of the first electrode 221 and the second electrode 222 located outside the bending region 223 of the first segment 2211. This can be that the first segment 2211 supports the electrode outside the first segment 2211 in only one bending region 223, or the first segment 2211 supports the electrode in two bending regions 223, depending on the length of the first segment 2211.

[0133] In some embodiments, the length of the first segment 2211 is L1, the length of the first sub-segment 2212a is L2, and the relationship between L1 and L2 can be: 3mm≤L1≤6*L2.

[0134] In some embodiments, please continue to refer to Figure 5 The first segment 2211 extends inward from its junction with the second segment 2212 (first junction a) and bypasses a bending region 223. That is, the first segment 2211 supports the electrode in only one bending region 223, and the first segment 2211 includes only one bending part 2211a. The first segment 2211 of this structure is shorter, which saves materials and reduces costs.

[0135] Optionally, the winding start end 225a of the first electrode 221 and the winding start end 225b of the second electrode 222 are both located within the flat region 224. The portion of the first electrode 221 extending from its winding start end 225a to a bend region 223 is offset from the portion of the second electrode 222 extending from its winding start end 225b to another bend region 223 in the second direction C. The second direction C is perpendicular to the first direction B and the flat region 224. This structure effectively reduces the thickness difference between the two sides of the winding structure in the first direction B, ensuring the consistency of the thickness on both sides of the winding structure in the first direction B, and improving the energy density of the electrode assembly 22.

[0136] The second direction C is perpendicular to the flat region 224. It can be understood that the second direction C is perpendicular to the part of the first electrode 221 and the second electrode 222 located in the flat region 224. The second direction C is the thickness direction of the winding structure. The second direction C is also the thickness direction of the part of the first electrode 221 and the second electrode 222 located in the flat region 224.

[0137] The portion of the first electrode 221 extending from the winding start end 225a to a bending region 223 is a first portion 2211b. The first portion 2211b is located in the straight region 224. The first portion 2211b intersects with the bending portion 2211a. The intersection of the first portion 2211b and the bending portion 2211a is located at the intersection of the straight region 224 and the bending region 223. The portion of the second electrode 222 extending from the winding start end 225b to another bending region 223 is a second portion 2221. The second portion 2221 is located in the straight region 224.

[0138] For example, the relationship between L1 and L2 can be: 3mm≤L1<0.75*L2.

[0139] In other embodiments, please refer to Figure 15 , Figure 15 This is a schematic diagram of the structure of the electrode assembly 22 provided in some embodiments of this application. Alternatively, the portion of the first electrode 221 extending from the winding start end 225a of the first electrode 221 to a bending region 223 may at least partially overlap with the portion of the second electrode 222 extending from the winding start end 225b of the second electrode 222 to another bending region 223 in the second direction C. That is, the first portion 2211b and the second portion 2221 at least partially overlap. Here, "at least partially overlap" means that the projection of the first portion 2211b in the second direction C at least partially overlaps with the projection of the second portion 2221 in the second direction C.

[0140] In some embodiments, please refer to Figure 16 and Figure 17 As shown, Figure 16 This is a schematic diagram of the structure of the electrode assembly 22 provided in other embodiments of this application. Figure 17 This is a schematic diagram of the structure of the electrode assembly 22 provided in some other embodiments of this application. The first segment 2211 extends inward from its junction with the second segment 2212 (first junction a) and bypasses two bending regions 223. That is, the first segment 2211 can support the electrode in the two bending regions 223. The first segment 2211 can provide support for the portions of the first electrode 221 and the second electrode 222 located in the two bending regions 223, making the structure of the first electrode 221 and the second electrode 222 in the portions of the two bending regions 223 more compact and reducing the occurrence of lithium plating.

[0141] In this embodiment, the first segment 2211 includes a plurality of bends 2211a, some of which are located in one bend area 223 and others are located in another bend area 223.

[0142] In a non-restrictive example, such as Figure 16 As shown, the first segment 2211 includes two bends 2211a, which are located in two bend areas 223 respectively.

[0143] For example, the relationship between L1 and L2 can be: 0.75*L2≤L1<1.25*L2.

[0144] In another non-restrictive example, such as Figure 17 As shown, the first segment 2211 includes three bends 2211a, one bend 2211a is located in one bend area 223, and the other two bends 2211a are located in another bend area 223.

[0145] For example, the relationship between L1 and L2 can be: 1.25*L2≤L1≤6*L2.

[0146] Please refer to Figure 18 , Figure 18 The flowchart illustrates a method for manufacturing an electrode assembly 22 according to some embodiments of this application. The method for manufacturing the electrode assembly 22 includes:

[0147] S100: Provides a first electrode 221 and a second electrode 222;

[0148] S200: The first electrode 221 and the second electrode 222 are wound along the winding direction A to form a winding structure, the winding structure including a bending region 223.

[0149] The first electrode 221 includes a first segment 2211 extending beyond the winding start end 225a of the first electrode 221. At least a portion of the first segment 2211 is used to provide support for the portions of the first electrode 221 and the second electrode 222 in the bending region 223 and located outside the first segment 2211.

[0150] In some embodiments, an isolation membrane 227 is also provided for separating the first electrode 221 and the second electrode 222, wherein the first electrode 221, the isolation membrane 227 and the second electrode 222 are wound along the winding direction A to form a wound structure.

[0151] The structure of the electrode assembly 22 manufactured by the above-described manufacturing method can be found in the electrode assembly 22 provided in the above embodiments.

[0152] Please refer to Figure 19 , Figure 19This is a schematic block diagram of a manufacturing apparatus 2000 for an electrode assembly 22 provided in some embodiments of this application. The electrode assembly 22 includes a first providing device 2100, a second providing device 2200, and an assembly device 2300.

[0153] The first providing device 2100 is used to provide a first electrode 221. The second providing device 2200 is used to provide a second electrode 222. The assembly device 2300 is used to wind the first electrode 221 and the second electrode 222 along the winding direction A to form a winding structure, the winding structure including a bending region 223.

[0154] The first electrode 221 includes a first segment 2211 extending beyond the winding start end 225a of the first electrode 221. At least a portion of the first segment 2211 is used to provide support for the portions of the first electrode 221 and the second electrode 222 in the bending region 223 and located outside the first segment 2211.

[0155] In some embodiments, the manufacturing equipment 2000 for electrode assembly 22 further includes a third providing device (not shown), which is used to provide a separating membrane 227 that separates the first electrode 221 and the second electrode 222, and the assembly device 2300 is used to wind the first electrode 221, the separating membrane 227 and the second electrode 222 along the winding direction A to form a winding structure.

[0156] The structure of the electrode assembly 22 manufactured by the manufacturing equipment 2000 described above can be found in the electrode assembly 22 provided in the above embodiments.

[0157] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0158] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit this application. For those skilled in the art, this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An electrode assembly, comprising a first electrode and a second electrode, wherein the first electrode and the second electrode are wound along a winding direction to form a winding structure, the winding structure including a bending region; The first electrode includes a first segment extending beyond the starting end of the winding of the second electrode, at least a portion of the first segment being used to provide support for the portions of the first electrode and the second electrode located in the bending region and outside the first segment; The first electrode further includes a second segment arranged continuously with the first segment along the winding direction, the junction of the first segment and the second segment being located inside the winding start end of the second electrode; at least a portion of the first segment is supported on the inside of the second electrode in the bending region. The electrode assembly further includes a separator for isolating the first electrode and the second electrode. The separator includes a first separator and a second separator. The first separator, the second electrode, the second separator and the first electrode are stacked in sequence and wound along the winding direction to form the winding structure. The starting ends of both the first and second separators extend beyond the starting end of the first electrode. The portions of the first and second separators extending beyond the starting end of the first electrode are wound inward toward the inside of the first segment. Furthermore, the portion of the first segment located in the bending area is supported on the inside of the bending area by the first and second separators. The winding structure also includes a straight section, and the bending section is provided at both ends of the straight section; The first electrode has its winding start end located within the flat region; and / or, the second electrode has its winding start end located within the flat region; the first segment extends inward from the junction and bypasses one of the bending regions.

2. The electrode assembly according to claim 1, wherein, The second segment includes a first sub-segment that is continuously arranged with the first segment along the winding direction; The first segment has only one side facing the active material layer of the second electrode, and the first segment is wound outward from the junction along the winding direction once. The first segment includes a bent portion arranged in the bending area, the bent portion being supported by the first sub-segment within the bending area.

3. The electrode assembly according to claim 2, wherein, Both sides of the first sub-segment are coated with an active material layer; or the side of the first sub-segment opposite to the active material layer of the second electrode is coated with an active material layer, while the other side of the first sub-segment is not coated with an active material layer.

4. The electrode assembly according to claim 3, wherein, The second segment also 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 sequentially and continuously along the winding direction; Both sides of the second sub-segment are opposite to the active material layer of the second electrode; The third segment faces the active material layer of the second electrode only on one side; The third sub-segment is coated with an active material layer on both sides; or the side of the third sub-segment opposite to the active material layer of the second electrode is coated with an active material layer, while the other side of the third sub-segment is not coated with an active material layer.

5. The electrode assembly according to claim 4, wherein, The second paragraph also includes a fourth sub-paragraph; The first segment, the first sub-segment, the second sub-segment, the third sub-segment, and the fourth sub-segment are arranged sequentially and continuously along the winding direction; Neither side of the fourth sub-segment is opposite to the active material layer of the second electrode; The fourth sub-segment is coated with an active material layer on both sides, or the fourth sub-segment is coated with an active material layer on its inner side, while the other side of the fourth sub-segment is not coated with an active material layer.

6. The electrode assembly according to claim 5, wherein, The winding start end of the first electrode and the winding start end of the second electrode are both located within the flat region; The two bending areas are located at both ends of the straight area in the first direction; The portion of the first electrode extending from the starting end of the first electrode to a bend area is offset from the portion of the second electrode extending from the starting end of the second electrode to another bend area in a second direction. The second direction is perpendicular to the first direction and the straight region.

7. The electrode assembly according to any one of claims 1-6, wherein, The first electrode is the negative electrode, and the second electrode is the positive electrode.

8. The electrode assembly according to claim 7, wherein, Both sides of the first segment are coated with a negative electrode active material layer.

9. A battery cell, comprising a housing and an electrode assembly according to any one of claims 1-8; The electrode assembly is housed within the housing.

10. A battery, comprising a housing and a battery cell according to claim 9; The individual battery cells are housed within the casing.

11. An electrical device comprising the battery of claim 10.

12. A method for manufacturing an electrode assembly, comprising: Provide the first electrode and the second electrode; The first electrode and the second electrode are wound along the winding direction to form a winding structure, the winding structure including a bending area; The first electrode includes a first segment extending beyond the starting end of the winding of the second electrode, and at least a portion of the first segment is used to provide support force to the portion of the first electrode and the second electrode located in the bending area and outside the first segment. The first electrode further includes a second segment arranged continuously with the first segment along the winding direction, the junction of the first segment and the second segment being located inside the winding start end of the second electrode; at least a portion of the first segment is supported on the inside of the second electrode in the bending region. The electrode assembly further includes a separator for isolating the first electrode and the second electrode. The separator includes a first separator and a second separator. The first separator, the second electrode, the second separator and the first electrode are stacked in sequence and wound along the winding direction to form the winding structure. The starting ends of both the first and second separators extend beyond the starting end of the first electrode. The portions of the first and second separators extending beyond the starting end of the first electrode are wound inward toward the inside of the first segment. Furthermore, the portion of the first segment located in the bending area is supported on the inside of the bending area by the first and second separators. The winding structure also includes a straight section, and the bending section is provided at both ends of the straight section; The first electrode has its winding start end located within the flat region; and / or, the second electrode has its winding start end located within the flat region; The first segment extends inward from the junction and around one of the bends.

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