Cross-reference of applications related to electrode assemblies, battery cells, batteries, and power consumption devices.

Abstract

The present invention provides an electrode assembly, a manufacturing method and a manufacturing system thereof, a battery cell, a battery, and a power consumption device. The electrode assembly of the present invention includes a first polarity sheet, a second polarity sheet, and a first separator, the polarities of the first polarity sheet and the second polarity sheet are opposite, the first separator is used to separate the first polarity sheet and the second polarity sheet, and the first polarity sheet, the second polarity sheet, and the first separator are wound along the winding direction. The electrode assembly has a folding region, and a second separator is provided in the folding region, the second separator is stacked with the first separator, and is used to separate the adjacent first polarity sheet and the second polarity sheet, and at least some ions desorbed from the first polarity sheet pass through the first separator and the second separator and are inserted into the second polarity sheet. The first separator and the second separator jointly separate the first polarity sheet and the second polarity sheet in the folding region, thereby effectively reducing the problem of the electrode assembly being short-circuited due to the breakage of the separator.

Description

Technical Field

[0001] This application claims the priority of Chinese Patent Application No. 202111062600.7, filed on September 10, 2021, with the invention title "Electrode Assembly and Related Battery Cell, Battery, Device and Manufacturing Method", and the entire content of the application is incorporated herein by reference.

[0002] This application relates to the field of battery technology, specifically to an electrode assembly, its manufacturing method and manufacturing system, a battery cell, a battery and an electric power consumption device.

Background Art

[0003] Battery cells are widely used in electronic devices such as mobile phones, notebook computers, battery cars, electric vehicles, electric aircraft, electric ships, electric toy cars, electric toy ships, electric toy aircraft and electric tools. The battery cells can include nickel-cadmium battery cells, nickel-hydrogen battery cells, lithium-ion battery cells and secondary alkaline zinc-manganese battery cells, etc.

[0004] In the development of battery technology, in addition to improving the performance of battery cells, safety issues are also important issues that cannot be ignored. If the safety issues of battery cells cannot be guaranteed, the battery cells cannot be used. Therefore, how to improve the safety of battery cells is an urgent technical problem to be solved in battery technology.

Summary of the Invention

[0005] This application provides an electrode assembly with improved safety, its manufacturing method and manufacturing system, a battery cell, a battery and an electric power consumption device.

[0006] According to a first aspect, an embodiment of the present application provides an electrode assembly comprising a first polar sheet, a second polar sheet, and a first separator, wherein the polarities of the first and second polar sheets are opposite, and the first separator is used to separate the first and second polar sheets, and the first polar sheet, the second polar sheet, and the first separator are wound along the winding direction. The electrode assembly has a bent region, in which a second separator is provided, the second separator is stacked with the first separator and is used to separate adjacent first and second polar sheets, and at least some of the ions detached from the first polar sheet pass through the first and second separators and are inserted into the second polar sheet.

[0007] In this invention, the first separator and the second separator work together to separate the first polar sheet and the second polar sheet in the bending region. Therefore, even if lithium deposition occurs in the bending region or burrs are generated on the polar sheet during the bending process, it is difficult for lithium dendrites or burrs to simultaneously penetrate the first separator and the second separator. This reduces the probability of the first polar sheet and the second polar sheet becoming conductive, effectively reducing the problem of the electrode assembly short-circuiting due to separator damage, effectively lowering the risk of electrode assembly failure, and improving the service life and safety of the electrode assembly. Both the first separator and the second separator are ion-permeable, reducing ion inhibition and ensuring the capacity of the electrode assembly.

[0008] In some embodiments, the thickness of the second separator is greater than the thickness of the first separator.

[0009] In the above embodiment, the second separator is less likely to be punctured than the first separator, thereby effectively reducing the risk of damage to the second separator and improving safety.

[0010] In some embodiments, the second separator includes a plurality of separation layers stacked in the thickness direction of the second separator.

[0011] In the above embodiment, the multilayer structure can improve safety by increasing the strength of the second separator and reducing the possibility of the second separator being punctured.

[0012] In some embodiments, adjacent separation layers are bonded to each other.

[0013] In the above embodiment, the multiple separation layers are bonded together, thereby reducing the risk of displacement between the multiple separation layers during the winding process of the electrode assembly and ensuring a protective effect on the bending region of the second separator.

[0014] In some embodiments, the separation layers include a first separation layer and a second separation layer installed adjacent to each other, with the first separation layer located between the second separation layer and the first separator. In the winding direction, the end of the second separation layer is offset from the end of the first separation layer.

[0015] In the above embodiment, by offsetting the ends of the second separation layer and the first separation layer, the ends of the second separation layer and the first separation layer press against different regions of the polar sheet, thereby reducing stress concentration, lowering the risk of the polar sheet tearing, and improving the performance of the polar sheet.

[0016] In some embodiments, in the winding direction, both ends of the second separation layer extend beyond the first separation layer and are attached to the first separator.

[0017] In the above embodiment, the second separation layer is attached to the first separator, and the movement of the first separation layer in the winding direction can be restricted, thereby reducing the risk of the first and second separation layers being offset or shifted along the winding direction during the charging and discharging process, ensuring a protective effect on the bending region of the second separator, and improving safety.

[0018] In some embodiments, the electrode assembly further includes a flat region connected to the bending region. The entire first separation layer is located in the bending region. Both ends of the second separation layer along the winding direction are located in the flat region.

[0019] In the above embodiment, the first and second separation layers can simultaneously provide protection to the folded region, reducing the risk of short circuits and improving safety. The entire first separation layer is located in the folded region, thereby preventing the first separation layer from affecting ion transmission in the flat region and ensuring the charge and discharge performance of the flat region. Both ends of the second separation layer along the winding direction are located in the flat region, thereby offsetting the ends of the second separation layer from the ends of the first separation layer and reducing stress concentration.

[0020] In some embodiments, the first separation layer is attached to the first separator.

[0021] The above embodiment can reduce the risk of the first separation layer being offset or shifted along the winding direction, ensure the protective effect of the first separation layer on the folded area, and improve safety.

[0022] In some embodiments, the material of the separation layer is the same as the material of the first separator, and the thickness of the separation layer is equal to the thickness of the first separator.

[0023] In the above embodiment, the first separator and the second separator can be manufactured using separators of the same specifications, thereby simplifying the process and reducing costs.

[0024] In some embodiments, the porosity of the second separator is greater than or equal to that of the first separator.

[0025] In the above embodiment, the second separator has excellent ion permeability, thereby reducing the ion inhibition of the second separator and ensuring the capacity of the electrode assembly.

[0026] In some embodiments, the second separator is provided between at least the innermost adjacent first-polarity sheet and second-polarity sheet within the bending region.

[0027] By installing the second separator in areas where the problem of lithium precipitation is severe, the above embodiments can effectively reduce the problem that the electrode assembly is short-circuited due to the breakage of the separator, and improve the service life and safety of the electrode assembly.

[0028] In some embodiments, a plurality of second separators are provided in the bending region, and adjacent second separators are separated by the first-polarity sheet or the second-polarity sheet. Among the adjacent second separators, the thickness of the inner second separator is greater than the thickness of the outer second separator.

[0029] In the above embodiments, the inner second separator has a greater thickness, which can reduce the risk of being pierced as much as possible. Since the risk of the outer second separator being pierced is low, it may have a smaller thickness, thereby saving the amount of the second separator used and improving the energy density of the electrode assembly.

[0030] In some embodiments, the electrode assembly further includes a flat region connected to the bending region, and both ends along the winding direction of the second separator are located in the flat region.

[0031] In the above embodiments, the second separator can completely separate the first-polarity sheet and the second-polarity sheet, thereby improving safety.

[0032] In some embodiments, the second separator is attached to the outer surface of the first separator.

[0033] In the above embodiment, the second separator is attached to the outer surface of the first separator, thereby reducing the risk of the second separator being offset or shifted along the winding direction during the charging and discharging process, as well as reducing the risk of the second separator being stretched under the action of the first separator and becoming wrinkled.

[0034] In some embodiments, the second polarity sheet is a negative electrode sheet, and the second separator is attached to the outer surface of the second polarity sheet.

[0035] In the above embodiment, the second separator is attached to the outer surface of the second polar sheet, and the second separator is stretched under the action of the second polar sheet, thereby reducing the risk of the second separator becoming wrinkled.

[0036] According to a second aspect, an embodiment of the present application provides a battery cell including an outer case and an electrode assembly according to any embodiment of the first aspect housed within the outer case.

[0037] According to a third aspect, an embodiment of the present application provides a battery including a battery cell according to a plurality of embodiments of a second aspect.

[0038] According to a fourth aspect, an embodiment of the present application provides a power consumption device including a battery cell of a second aspect for supplying electrical energy.

[0039] According to the fifth aspect, the embodiments of the present application are as follows: The steps include providing a first polarity sheet, a second polarity sheet, a first separator, and a second separator. The process includes the steps of winding a first polar sheet, a second polar sheet, and a first separator along the winding direction, and forming a folded region, The present invention provides a method for manufacturing an electrode assembly, wherein the polarities of the first polar sheet and the second polar sheet are opposite, a first separator is used to separate the first polar sheet and the second polar sheet, a second separator is provided in the bending region, the second separator is stacked with the first separator and is used to separate adjacent first polar sheets and second polar sheets, and at least some of the ions detached from the first polar sheet pass through the first separator and the second separator and are inserted into the second polar sheet.

[0040] According to a sixth aspect, an embodiment of the present application provides a manufacturing system for an electrode assembly comprising a supplying device and a winding device. The supplying device is used to supply a first polar sheet, a second polar sheet, a first separator, and a second separator. The winding device is used to wind the first polar sheet, the second polar sheet, and the first separator along the winding direction and to form a folded region. The polarities of the first polar sheet and the second polar sheet are opposite, the first separator is used to separate the first polar sheet and the second polar sheet, the second separator is provided in the folded region, the second separator is stacked with the first separator and is used to separate adjacent first polar sheets and second polar sheets, at least some of the ions detached from the first polar sheet pass through the first separator and the second separator and are inserted into the second polar sheet. [Brief explanation of the drawing]

[0041] To more clearly explain the technical solutions in the embodiments of this application, the necessary drawings for the embodiments are briefly described below. It should be understood that the drawings shown below represent only a few embodiments of this application, and those skilled in the art can obtain further drawings based on these drawings without requiring any creative effort.

[0042] [Figure 1] This is a schematic diagram of the structure of a vehicle according to several embodiments of the present invention. [Figure 2] This is a schematic diagram of the disassembled battery according to some embodiments of the present invention. [Figure 3]This is a schematic diagram of an exploded view of a battery cell according to some embodiments of the present invention. [Figure 4] This is a schematic diagram of the structure of an electrode assembly according to some embodiments of the present application. [Figure 5] Figure 4 is a localized, magnified schematic diagram of the electrode assembly shown. [Figure 6] This is a schematic diagram of the local structure of an electrode assembly according to another embodiment of the present application. [Figure 7] This is a schematic diagram of the local structure of an electrode assembly according to yet another embodiment of the present application. [Figure 8] This is a schematic diagram of the local structure of an electrode assembly according to yet another embodiment of the present application. [Figure 9] This is a flowchart of a method for manufacturing an electrode assembly according to some embodiments of the present invention. [Figure 10] This is a schematic block diagram of a manufacturing system for an electrode assembly according to several embodiments of the present invention. In the drawings, the figures are not drawn to actual proportions. [Modes for carrying out the invention]

[0043] To further clarify the purpose, technical solutions, and advantages of the embodiments of this application, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the drawings of the embodiments. Clearly, the embodiments described are some, but not all, embodiments of this application. All other embodiments obtained by a person skilled in the art without requiring any creative effort based on the embodiments of this application are all within the scope of protection of this application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art. Terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit the application. The terms “including” and “having” and their synonyms in the description of the specification, claims, and drawings are not intended to be exclusive. Terms such as “first,” “second,” etc., in the specification, claims, or drawings are used to distinguish different subjects and are not used to describe a particular order or subordination.

[0045] In the description of this application, terms such as "center," "lateral direction," "length," "width," "top," "bottom," "front," "back," "left," "right," "vertical," "horizontal," "upper part," "bottom," "inside," "outside," "axial direction," "radial direction," and "circumferential direction" indicate directions or positional relationships that are based on the directions or positional relationships shown in the drawings. These terms are merely used to simplify the description of this application and to make it easier to explain. They do not indicate or imply that the device or element in question has a specific direction, or that it should be composed of and operated in a specific direction, and therefore should not be understood as limiting this application.

[0046] In the description of this application, unless otherwise specifically defined and limited, the terms “attach,” “connect,” “connection,” and “attachment” should be understood in a broad sense, for example, a fixed connection, a removable connection, or an integral connection. They may be directly connected, indirectly connected via an intermediate medium, or internally connected between two elements. A person skilled in the art will be able to understand the specific meaning of these terms in this application depending on the specific circumstances.

[0047] References to “Examples” in this specification mean that certain features, structures, or properties described in relation to the Examples may be included in at least one Example of the Application. Where the term “Examples” appears elsewhere in this specification, it does not necessarily refer to the same Example, nor does it refer to an Example that is mutually exclusive, independent, or substitutable with other Examples. Those skilled in the art will understand, both explicitly and implicitly, that the Examples described herein can be combined with other Examples.

[0048] In this specification, the term "and / or" merely describes the relationship or connection between related objects, indicating that three types of relationships are possible. For example, A and / or B can represent three situations: A existing alone, A and B existing simultaneously, and B existing alone. In this specification, the symbol " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0049] In this application, "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple sheets" refers to two or more sheets (including two sheets).

[0050] In this application, the battery cell may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, and the embodiments of this application are not limited thereto. The battery cell may be cylindrical, flattened, rectangular, or have other shapes, and the embodiments of this application are not limited thereto. Battery cells are generally classified into three types according to their packaging: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application are not limited thereto.

[0051] A battery cell includes an electrode assembly and an electrolyte, the electrode assembly consisting of a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell operates primarily through 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 being coated on the surface of the positive electrode current collector, and current collectors without the positive electrode active material layer protruding from the current collectors with the positive electrode active material layer, with the current collectors without the positive electrode active material layer forming the positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive electrode current collector may be aluminum, and the positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. 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. Current collectors without the negative electrode active material layer protrude from the current collectors with the negative electrode active material layer, and these uncoated current collectors form the negative electrode tabs. The negative electrode current collector may be made of copper, and the negative electrode active material may be carbon or silicon, etc. To ensure that melting does not occur due to high current, there are multiple positive electrode tabs, and the negative electrode tabs are also multiple, and they are laminated together. The separator material may be PP (polypropylene) or PE (polyethylene), etc. The development of battery technology requires simultaneous consideration of various design elements, such as performance parameters including energy density, cycle life, discharge capacity, and charge / discharge efficiency, as well as battery safety.

[0052] The batteries referred to in the embodiments of this application refer to a single physical module containing one or more battery cells to provide higher voltage and capacity. For example, the batteries referred to in this application may include battery modules or battery packs. The batteries generally include a housing for packaging one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging and discharging of the battery cells.

[0053] The separator is electrically insulating and is placed between the positive electrode sheet and the negative electrode sheet. Its main function is to prevent the positive and negative electrode sheets from coming into contact and causing an internal short circuit in the electrode assembly. The separator has numerous through-pores to ensure the free passage of electrolyte ions, and in particular, the separator has excellent permeability to lithium ions. Exemplarily, the separator includes a separation substrate layer which may be at least one of polypropylene, polyethylene, ethylene-propylene copolymer, polybutylene terephthalate, etc., and a functional layer which is located on the surface of the separation substrate layer and may be a mixture layer of ceramic oxide and binder.

[0054] Separators play a crucial role in electrode assemblies and can directly cause phenomena such as short circuits, reduced performance, and decreased lifespan of the electrode assembly.

[0055] During battery cell charging, metal ions detach from the positive electrode active material layer and are inserted into the negative electrode active material layer. However, if an abnormality occurs, metal ions may precipitate. Taking lithium-ion battery cells as an example, if there is insufficient lithium insertion space in the negative electrode active material layer, or if the resistance when lithium ions are inserted into the negative electrode active material layer is too high, or if lithium ions detach rapidly from the positive electrode active material layer, it may not be possible to insert an equal amount of the detached lithium ions into the negative electrode active material layer of the negative electrode sheet. In such cases, the lithium ions that are not inserted into the negative electrode sheet acquire electrons only on the surface of the negative electrode sheet, thereby forming elemental metallic lithium. This phenomenon is known as lithium deposition.

[0056] During their research and development, the inventors discovered that wound electrode assemblies are prone to lithium deposition in their bent regions. Further research revealed that the main cause of this lithium deposition phenomenon is that the positive and negative electrode sheets located in the bent region need to be bent, but during the bending process, stress concentration occurs in the positive and negative electrode active material layers, and the active material is prone to detachment. Detachment of the active material, particularly the active material on the negative electrode sheet, can cause the number of lithium insertion sites in the negative electrode active material layer of the negative electrode sheet to become less than the number of lithium ions that the positive electrode active material layer of the adjacent positive electrode sheet can provide, potentially leading to lithium deposition.

[0057] If lithium deposition is severe, the detached lithium ions form lithium crystals on the surface of the negative electrode sheet. Because the separator is thin, the lithium crystals can easily penetrate the separator, creating a risk of short-circuiting between adjacent positive and negative electrode sheets, thus posing a safety risk.

[0058] Furthermore, because positive or negative electrode sheets are prone to developing certain minute cracks and burrs during the winding and bending processes, under large stresses, the separator can be punctured, causing a short circuit in the electrode assembly and easily leading to thermal runaway phenomena such as ignition and explosion in the battery cell.

[0059] In view of this, the inventors of the present invention provide an electrode assembly that increases the number of separator layers in the bending region, thereby reducing the probability of separator failure in the electrode assembly, lowering the risk of internal short circuits between the first and second polarity sheets, and improving service life and safety.

[0060] The electrode assembly described in the embodiment of this application is applicable to battery cells, batteries, and power consumption devices that use batteries.

[0061] Power consumption devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and power tools. Vehicles may be gasoline-powered vehicles, natural gas vehicles, or new energy vehicles, and new energy vehicles may be pure electric vehicles, hybrid vehicles, or range-extender vehicles. Spacecraft include aircraft, rockets, spaceplanes, and spacecraft. Electric toys include stationary or mobile electric toys such as game consoles, electric car toys, electric boat toys, and electric aircraft toys. Power tools include metal cutting power tools such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, electric impact drivers, concrete vibrators, and electric planers, as well as polishing power tools, assembly power tools, and railway power tools. The embodiments of this application are not particularly limited to the above-mentioned power consumption devices.

[0062] For the sake of explanation, the following embodiments will use a vehicle as an example of a power consumption device.

[0063] Figure 1 is a schematic diagram of the structure of a vehicle according to some embodiments of the present invention. As shown in Figure 1, a battery 2 is installed inside the vehicle 1, and the battery 2 may be installed at the bottom, front, or rear of the vehicle 1. The battery 2 can be used to supply power to the vehicle 1, and can be used, for example, as the operating power source for the vehicle 1.

[0064] Vehicle 1 may further include a controller 3 and a motor 4, the controller 3 being used to control the battery 2 to supply power to the motor 4, for example, to meet the power requirements for starting, navigating, and driving Vehicle 1.

[0065] In some embodiments of the present invention, the battery 2 can provide driving power to the vehicle 1 not only as an operating power source for the vehicle 1, but also as a driving power source for the vehicle 1, by substituting for or partially substituting for fuel or natural gas.

[0066] Figure 2 is a schematic exploded view of a battery according to some embodiments of the present invention. As shown in Figure 2, the battery 2 includes a housing 5 and a battery cell 6, the battery cell 6 being housed within the housing 5.

[0067] The housing 5 is used to house the battery cells 6, and the housing 5 may have various structures. In some embodiments, the housing 5 may include a first housing portion 51 and a second housing portion 52, the first housing portion 51 and the second housing portion 52 overlapping each other, and together they define a housing space 53 for housing the battery cells 6. The second housing portion 52 may be a hollow structure with one end open, and the first housing portion 51 may be a plate-like structure, with the first housing portion 51 overlapping the open side of the second housing portion 52 to form a housing 5 having a housing space 53. Alternatively, both the first housing portion 51 and the second housing portion 52 may be hollow structures with one side open, with the open side of the first housing portion 51 overlapping the open side of the second housing portion 52 to form a housing 5 having a housing space 53. The first housing portion 51 and the second housing portion 52 may have various shapes such as cylinders and rectangular parallelepipeds.

[0068] To improve the airtightness after connecting the first housing section 51 and the second housing section 52, sealing members such as sealing material and sealing rings may be installed between the first housing section 51 and the second housing section 52.

[0069] When the first housing section 51 is placed over the upper part of the second housing section 52, the first housing section 51 can be called the upper housing cover and the second housing section 52 can be called the lower housing.

[0070] In battery 2, there are multiple battery cells 6. Multiple battery cells 6 can be connected in series, in parallel, or in series-parallel. Series-parallel connection means that multiple battery cells 6 can be connected in both series and parallel. Multiple battery cells 6 can be directly connected in series, in parallel, or in series-parallel, and then the entire assembly composed of multiple battery cells 6 can be housed in the housing 5. Alternatively, multiple battery cells 6 may first be connected in series, in parallel, or in series-parallel to form a battery module, and then the multiple battery modules may be further connected in series, in parallel, or in series-parallel to form a single unit which can then be housed in the housing 5.

[0071] Figure 3 is an exploded schematic diagram of a battery cell according to some embodiments of the present application. The battery cell 6 is the smallest unit constituting the battery 2. As shown in Figure 3, the battery cell 6 includes an outer case, an electrode assembly 100 housed within the outer case, and other functional components.

[0072] In some embodiments, the outer case includes an end cover 61 and a housing 62.

[0073] The end cover 61 is a component that is placed over the opening of the housing 62 to isolate the internal environment of the battery cell 6 from the external environment. The shape of the end cover 61 can be adapted to the shape of the housing 62 and fitted into the housing 62, but is not limited to this. Preferably, the end cover 61 can be manufactured from a material having a certain hardness and strength (for example, an aluminum alloy), so that the end cover 61 is less likely to deform even if it is pressed or struck, the battery cell 6 can have higher structural strength and improved safety performance. Functional components such as electrode terminals may be provided on the end cover 61. The electrode terminals can be electrically connected to the electrode assembly 100 and are used to output electrical energy from the battery cell 6.

[0074] In some embodiments, the end cover 61 may be further equipped with a pressure reduction mechanism used to release internal pressure when the internal pressure or temperature of the battery cell 6 reaches a threshold. The end cover 61 may be made of any material, such as copper, iron, aluminum, stainless steel, aluminum alloy, or plastic, and the embodiments of this application are not particularly limited thereto.

[0075] In some embodiments, an additional insulating member may be installed inside the end cover 61, which may be used to isolate electrical connection members in the housing 62 from the end cover 61, thereby reducing the risk of short circuits. Exemplarily, the insulator may be plastic, rubber, or the like.

[0076] The housing 62 is an assembly that fits with the end cover 61 to form the internal environment of the battery cell 6, which is used to house the electrode assembly 100, electrolyte, and other components. The housing 62 and the end cover 61 may be separate components, or the housing 62 may have an opening, and the end cover 61 may cover the opening to form the internal environment of the battery cell 6. The end cover 61 and the housing 62 may be integrated, and specifically, the end cover 61 and the housing 62 may have a common connecting surface before other components are placed in the housing, and if it is necessary to seal the inside of the housing 62, the end cover 61 is placed over the housing 62, but is not limited to this. The housing 62 may be a rectangular parallelepiped, cylindrical, hexagonal prism, or various other shapes and sizes. Specifically, the shape of the housing 62 is determined by the specific shape and size of the electrode assembly 100. The housing 62 may be made of any material, such as copper, iron, aluminum, stainless steel, aluminum alloy, or plastic, and the embodiments of this application are not particularly limited thereto.

[0077] The electrode assembly 100 is a component in the battery cell 6 that is immersed in the electrolyte to generate an electrochemical reaction. One or more electrode assemblies 100 can be included in the housing 62. The electrode assembly 100 is mainly formed by winding a positive electrode sheet and a negative electrode sheet, and generally a separator is provided between the positive electrode sheet and the negative electrode sheet. The portions of the positive electrode sheet and the negative electrode sheet containing the active material constitute the main body of the electrode assembly 100, and the portions of the positive electrode sheet and the negative electrode sheet that do not contain the active material each constitute a tab. The positive electrode tab and the negative electrode tab may be located together at one end of the main body, or they may be located at both ends of the main body, respectively. During the charging and discharging process of the battery cell, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs are connected to the electrode terminals to form an electric current circuit.

[0078] Figure 4 is a schematic diagram of the structure of an electrode assembly according to several embodiments of the present application, and Figure 5 is a localized enlarged schematic diagram of the electrode assembly shown in Figure 4.

[0079] As shown in Figures 4 and 5, the electrode assembly 100 of the embodiment of the present application includes a first polar sheet 110, a second polar sheet 120, and a first separator 131, wherein the polarities of the first polar sheet 110 and the second polar sheet 120 are opposite, the first separator 131 is used to separate the first polar sheet 110 and the second polar sheet 120, and the first polar sheet 110, the second polar sheet 120 and the first separator 131 are wound along the winding direction X. The electrode assembly 100 has a bending region B, in which a second separator 132 is provided. The second separator 132 is stacked with the first separator 131 and is used to separate the adjacent first polar sheet 110 and second polar sheet 120. At least some of the ions detached from the first polar sheet 110 pass through the first separator 131 and the second separator 132 and are inserted into the second polar sheet 120.

[0080] In this embodiment, the winding direction X is the direction in which the first polar sheet 110, the second polar sheet 120, and the first separator 131 are wound from the inside outwards. Exemplarily, in the figure, the winding direction X is counterclockwise.

[0081] One of the first polarity sheet 110 and the second polarity sheet 120 is a positive electrode sheet, and the other is a negative electrode sheet.

[0082] Both the first separator 131 and the second separator 132 have numerous through-pores, ensuring the free passage of metal ions. For example, the first separator 131 and the second separator 132 have excellent permeability to lithium ions and do not fundamentally hinder the passage of lithium ions. Exemplarily, the material of the first separator 131 and the second separator 132 may be PP (polypropylene) or PE (polyethylene), etc.

[0083] The first separator 131 and the second separator 132 may be manufactured from the same material or from different materials. In this embodiment, the thickness of the first separator 131 and the second separator 132 is not limited.

[0084] The separator referred to in this application can also be called a separator film, and although it is shown as a line in the figure, the separator actually has a similar thickness.

[0085] The first polar sheet 110, the second polar sheet 120, and the first separator 131 are all strip-shaped structures. In some embodiments, two first separators 131 are provided, and in this application, the first polar sheet 110, one first separator 131, the second polar sheet 120, and another first separator 131 are laminated in order first, and then wound two or more times to form a wound structure.

[0086] In this application, the winding device winds a first polar sheet 110, a second polar sheet 120, and a first separator 131 several times, and each winding can consist of multiple layers, with one winding starting from a point on the electrode assembly 100, completing one turn along the winding direction X, and reaching another point positioned as the end end, where the end end, the start end, and the center of the winding are collinear, and the start end is between the end end and the center of the winding. Each winding, in order, includes a first polar sheet layer, a first separator layer, a second polar sheet layer, and a second separator layer, and the first separator 131 is used to separate the first polar sheet 110 and the second polar sheet 120 of adjacent windings or adjacent layers within the same winding.

[0087] The first separator 131 should be understood as a single layer separator between the first polar sheet 110 and the second polar sheet 120 in the related technology, i.e., a base separator, and the second separator 132 should be understood as an additional separator, i.e., an extra separator.

[0088] The electrode assembly 100 may have various shapes; for example, the electrode assembly 100 may be cylindrical, flattened, prismatic (such as a triangular prism, square prism, or hexagonal prism), or other shapes.

[0089] Both the first polar sheet 110 and the second polar sheet 120 include a plurality of bent portions 150 located in the bending region B. The bending region B is the region of the electrode assembly 100 having a bent structure, and the portion of the first polar sheet 110 located in the bending region B (i.e., the bent portions 150 of the first polar sheet 110) and the portion of the second polar sheet 120 located in the bending region B (i.e., the bent portions 150 of the second polar sheet 120) are both installed in a bent state. Exemplarily, the bent portions 150 of the first polar sheet 110 and the bent portions 150 of the second polar sheet 120 are bent in a substantially arc shape.

[0090] In this embodiment, one second separator 132 may be provided in the folding region B, or multiple second separators 132 may be provided.

[0091] The second separator 132 is laminated between the polarity sheet and the first separator 131, and the polarity sheet may be the first polarity sheet 110 or the second polarity sheet 120. In some examples, the second separator 132 may be installed independently between the polarity sheet and the first separator 131, that is, the second separator 132 is laminated separately from the polarity sheet and the first separator 131, and there is no connection relationship such as adhesion between the second separator 132 and the polarity sheet, and between the second separator 132 and the first separator 131. In other examples, the second separator 132 may be attached to the surface of the polarity sheet or the surface of the first separator 131, where attachment refers to an attached connection, for example, the second separator 132 may be attached to the polarity sheet or the first separator 131 by means of adhesive or other methods.

[0092] The second separator 132 may be entirely located in the bending region B of the electrode assembly 100, or only a portion of it may be located in the bending region B of the electrode assembly 100.

[0093] In this embodiment, the first separator 131 and the second separator 132 work together to separate the first polar sheet 110 and the second polar sheet 120 in the bending region B. Therefore, even if lithium deposition occurs in the bending region B, or if burrs are generated on the polar sheets during the bending process, it is difficult for lithium dendrites or burrs to simultaneously penetrate the first separator 131 and the second separator 132. This reduces the probability of the first polar sheet 110 and the second polar sheet 120 becoming conductive, effectively reducing the problem of the electrode assembly 100 short-circuiting due to separator damage, effectively lowering the risk of electrode assembly 100 failure, and improving the service life and safety of the electrode assembly 100. Both the first separator 131 and the second separator 132 are ion-permeable, reducing ion inhibition and ensuring the capacity of the electrode assembly 100.

[0094] In some embodiments, the thickness of the second separator 132 is greater than the thickness of the first separator 131.

[0095] In this embodiment, the second separator 132 is less likely to be punctured than the first separator 131, thereby effectively reducing the risk of damage to the second separator 132 and improving safety.

[0096] In some embodiments, the porosity of the second separator 132 is greater than or equal to that of the first separator 131.

[0097] Porosity refers to the percentage of pore volume in a bulk material relative to its total volume in its natural state. Generally, porosity is measured by true density.

[0098] In this embodiment, the second separator 132 has excellent ion permeability, thereby reducing the inhibition of the second separator 132 by ions and ensuring the capacity of the electrode assembly 100.

[0099] In some embodiments, the porosity of the second separator 132 is greater than that of the first separator 131.

[0100] In some embodiments, the second separator 132 is provided within the folding region B, at least between the innermost adjacent first polar sheet 110 and the second polar sheet 120.

[0101] In the folded region B, the innermost first polar sheet 110 and second polar sheet 120 are prone to lithium deposition and burr formation. Specifically, compared to other folded portions 150 of the first polar sheet 110, the innermost folded portion 150 of the first polar sheet 110 has a larger curvature and is subjected to greater stress. Therefore, the innermost folded portion 150 of the first polar sheet 110 is prone to serious active material shedding and burr formation. Similarly, compared to other folded portions 150 of the second polar sheet 120, the innermost folded portion 150 of the second polar sheet 120 has a larger curvature and is subjected to greater stress. Therefore, the innermost folded portion 150 of the second polar sheet 120 is prone to serious active material shedding and burr formation.

[0102] This embodiment effectively reduces the problem of the electrode assembly 100 short-circuiting due to separator damage by installing the second separator 132 in areas where lithium deposition is a serious problem, thereby improving the service life and safety of the electrode assembly 100.

[0103] In some embodiments, a plurality of second separators 132 are provided in the folding region B, and adjacent second separators 132 are separated by a first polar sheet 110 or a second polar sheet 120. Of the adjacent second separators 132, the thickness of the inner second separator 132 is greater than the thickness of the outer second separator 132.

[0104] In the bending region B, the curvature of the bent portion 150 gradually decreases from the inside to the outside, and the stress on the bent portion 150 also gradually decreases. In other words, in the bending region B, the lithium deposition problem occurring in the inner bent portion 150 is more serious than the lithium deposition problem occurring in the outer bent portion 150.

[0105] In this embodiment, the inner second separator 132 has a greater thickness to minimize the risk of puncture. The outer second separator 132 has a lower risk of puncture and may have a smaller thickness, thereby saving on the amount of second separator 132 used and improving the energy density of the electrode assembly 100.

[0106] In some embodiments, multiple second separators 132 are installed independently. The position of each second separator 132 can be freely set as needed.

[0107] In some embodiments, the electrode assembly 100 further includes a flat region C connected to a bent region B, and both ends of the second separator 132 along the winding direction X are located in the flat region C.

[0108] The flat region C is a region of the electrode assembly 100 having a flat structure, and both the first polar sheet 110 and the second polar sheet 120 include a plurality of flat portions 160 located in the flat region C. The flat portions 160 within the flat region C are installed substantially flat, and exemplary, the flat portions 160 are substantially plate-shaped.

[0109] Exemplary, there are two bent regions B, each connected to both ends of a flat region C. A second separator 132 is installed in at least one bent region B, and preferably, a second separator 132 is installed in both bent regions B.

[0110] In this embodiment, the second separator 132 can completely separate the first polar sheet 110 and the second polar sheet 120, thereby improving safety.

[0111] In some embodiments, the second separator 132 is attached to the outer surface of the first separator 131.

[0112] The second separator 132 may be attached entirely to the first separator 131, or only partially to the first separator 131. Illustratively, the second separator 132 is attached to the first separator 131 at both ends along the winding direction X.

[0113] In this embodiment, the second separator 132 is attached to the first separator 131, thereby reducing the risk of the second separator 132 being offset or shifted along the winding direction X during the charging and discharging process, ensuring a protective effect on the bending region B of the second separator 132, and improving safety.

[0114] When the first separator 131 is bent, its inner surface is compressed and its outer surface is stretched. However, if the second separator 132 is attached to the inner surface of the first separator 131, the influence of the first separator 131 may cause wrinkles in the second separator 132, potentially affecting ion transport. In this embodiment, the second separator 132 is attached to the outer surface of the first separator 131, and the second separator 132 is stretched under the action of the first separator 131, thereby reducing the risk of wrinkles forming in the second separator 132.

[0115] In this application, the inner and outer sides of the electrode assembly 100 are defined as the side facing the winding center being the inner side and the side farther from the winding center being the outer side. That is, the surface of the first separator 131 facing the winding center is the inner surface, and the surface farther from the winding center is the outer surface.

[0116] In some embodiments, the second separator 132 is attached to the outer surface of the first separator 131 by thermocompression bonding.

[0117] In some embodiments, the materials of the first separator 131 and the second separator 132 may both be PP (polypropylene) or PE (polyethylene). Choosing such materials makes processing easier, reduces costs, and is advantageous for commercialization.

[0118] In some embodiments, the first separator 131 may be PP (polypropylene) or PE (polyethylene), and the second separator 132 may be one of the following: polypropylene / ultra-high molecular weight polyethylene separator / epoxy resin composite separator, porous polypropylene separator, coaxial composite nanofiber film, porous separator, glass fiber battery separator, or PVDF-HFP polymer electrolyte separator. Of these, the polypropylene / ultra-high molecular weight polyethylene separator / epoxy resin composite separator can improve the porosity and heat resistance of the separator. The porous polypropylene separator can achieve both air permeability and puncture strength. The coaxial composite nanofiber film is composed of composite nanofibers with a fluorine-containing insulating coating layer and a polyimide core layer, ensuring not only excellent permeability, liquid retention, and ionic conductivity, but also high mechanical strength and heat resistance. The porous separator is manufactured by mixing polyolefin with silica or other inorganic substances. The glass fiber battery separator consists of alkali-free glass fiber, PET (polyester), and PA (polyamide). This increases the puncture strength and mechanical strength of the second separator 132, and strengthens the inhibitory effect on lithium dendrites.

[0119] In some embodiments, the second separator 132 includes a plurality of separation layers 1321 stacked along the thickness direction of the second separator 132.

[0120] In this embodiment, the multilayer structure improves the strength of the second separator 132, reduces the possibility of the second separator 132 being punctured, and thus improves safety.

[0121] In some embodiments, adjacent separation layers 1321 are bonded to each other.

[0122] In Figures 4 and 5, the separation layers 1321 are shown as lines. Although there are gaps between the separation layers 1321 in the figures, in reality, adjacent separation layers 1321 can be bonded together.

[0123] In this embodiment, the multiple separation layers 1321 are bonded together, thereby reducing the risk of displacement occurring between the multiple separation layers 1321 during the winding process of the electrode assembly 100, and ensuring the protective effect of the second separator 132 on the bending region B.

[0124] In some embodiments, multiple separation layers 1321 are bonded to each other by thermocompression bonding.

[0125] In some embodiments, the material of the separation layer 1321 is the same as the material of the first separator 131, and the thickness of the separation layer 1321 is equal to the thickness of the first separator 131.

[0126] In this embodiment, the first separator 131 and the second separator 132 can be manufactured using separators of the same specifications, thereby simplifying the process and reducing costs.

[0127] Figure 6 is a schematic diagram of the local structure of an electrode assembly according to another embodiment of the present application.

[0128] As shown in Figure 6, in some embodiments, the separation layers include a first separation layer 132a and a second separation layer 132b installed adjacent to each other, with the first separation layer 132a located between the second separation layer 132b and the first separator 131. In the winding direction X, the end of the second separation layer 132b is offset from the end of the first separation layer 132a.

[0129] "Installed with a staggered position" means that the end of the second separation layer 132b and the end of the first separation layer 132a do not overlap in the thickness direction of the second separator 132.

[0130] For example, two of the multiple separation layers are the first separation layer 132a and the second separation layer 132b, respectively.

[0131] The ends of the first separation layer 132a along the winding direction X are defined as the first end and the second end, respectively, and the ends of the second separation layer 132b along the winding direction X are defined as the third end and the fourth end, respectively. The third end is closer to the first end than the fourth end, and the fourth end is closer to the second end than the third end.

[0132] In this embodiment, the first and third ends are set up offset along the winding direction X. The second and fourth ends may be set up aligned along the winding direction X, or offset along the winding direction X.

[0133] During the charging and discharging process, the first polar sheet 110 and the second polar sheet 120 expand and press against the first separation layer 132a and the second separation layer 132b. When the edges of the first separation layer 132a and the second separation layer 132b are aligned, the edges of the first separation layer 132a and the second separation layer 132b press against the same location on the polar sheet, causing stress concentration and affecting the performance of the polar sheet.

[0134] In this embodiment, by offsetting the ends of the second separation layer 132b and the first separation layer 132a, the ends of the second separation layer 132b and the ends of the first separation layer 132a press against different regions of the polar sheet, thereby reducing stress concentration, lowering the risk of the polar sheet tearing, and improving the performance of the polar sheet.

[0135] In some embodiments, in the winding direction X, both ends of the second separation layer 132b extend beyond the first separation layer 132a and are attached to the first separator 131.

[0136] The first separation layer 132a may be installed independently between the second separation layer 132b and the first separator 131, or it may be attached to the second separation layer 132b or the first separator 131.

[0137] In this embodiment, the second separation layer 132b is attached to the first separator 131 and can restrict the movement of the first separation layer 132a in the winding direction X. This reduces the risk of the first separation layer 132a and the second separation layer 132b being offset or misaligned along the winding direction X during the charging and discharging process, ensuring a protective effect on the bending region B of the second separator 132 and improving safety.

[0138] In some embodiments, the first separation layer 132a is attached to the first separator 131.

[0139] The first separation layer 132a may be attached entirely to the first separator 131, or only partially to the first separator 131. For example, the first separation layer 132a may be attached to the first separator 131 at both ends along the winding direction X.

[0140] This embodiment can reduce the risk of the first separation layer 132a being offset or shifted along the winding direction X, ensuring the protective effect of the first separation layer 132a on the folded region B and improving safety.

[0141] Figure 7 is a schematic diagram of the local structure of an electrode assembly according to yet another embodiment of the present application.

[0142] As shown in Figure 7, in some embodiments, the electrode assembly 100 further includes a flat region C connected to a bent region B. The entire first separation layer 132a is located in the bent region B. Both ends of the second separation layer 132b along the winding direction X are located in the flat region C.

[0143] In this embodiment, the first separation layer 132a and the second separation layer 132b can simultaneously provide protection to the bending region B, reducing the risk of short circuits and improving safety. The entire first separation layer 132a is located in the bending region B, thereby preventing the first separation layer 132a from affecting ion transmission in the flat region C and ensuring the charge and discharge performance of the flat region C. Both ends of the second separation layer 132b along the winding direction X are located in the flat region C, thereby offsetting the ends of the second separation layer 132b from the ends of the first separation layer 132a and reducing stress concentration.

[0144] In some embodiments, the end of the first separation layer 132a along the winding direction X is located at the boundary between the flat region C and the folded region B.

[0145] Figure 8 is a schematic diagram of the local structure of an electrode assembly according to yet another embodiment of the present application.

[0146] As shown in Figure 8, the second polarity sheet 120 is a negative electrode sheet, and the second separator 132 is attached to the outer surface of the second polarity sheet 120.

[0147] In this embodiment, the second separator 132 is attached to the outer surface of the second polar sheet 120, and the second separator 132 is stretched under the action of the second polar sheet 120, thereby reducing the risk of the second separator 132 becoming wrinkled.

[0148] In the folded region B, the diameter of the positive electrode sheet outside the negative electrode sheet is larger than the diameter of the negative electrode sheet. Therefore, the area of ​​the positive electrode active material layer on the positive electrode sheet outside the negative electrode sheet is larger than the area of ​​the negative electrode active material layer on the negative electrode sheet, which makes it easier for lithium to precipitate on the outer surface of the negative electrode sheet. In this embodiment, the risk of short circuits is reduced and safety is improved by attaching the second separator 132 to the outer surface of the negative electrode sheet.

[0149] Figure 9 is a flowchart of a method for manufacturing an electrode assembly according to some embodiments of the present invention.

[0150] As shown in Figure 9, the method for manufacturing the electrode assembly in the embodiment of the present application is as follows: Step S100 provides a first polarity sheet, a second polarity sheet, a first separator, and a second separator. The process includes step S200, in which a first polar sheet, a second polar sheet, and a first separator are wound along the winding direction, and a folding region is formed. The polarities of the first polar sheet and the second polar sheet are opposite, a first separator is used to separate the first polar sheet and the second polar sheet, a second separator is provided in the folding region, the second separator is stacked with the first separator and is used to separate adjacent first and second polar sheets, and at least some of the ions detached from the first polar sheet pass through the first and second separators and are inserted into the second polar sheet.

[0151] Furthermore, the related structures of the electrode assemblies manufactured by the above-described electrode assembly manufacturing method can be referenced from the electrode assemblies provided in each of the above embodiments.

[0152] Figure 10 is a schematic block diagram of a manufacturing system for an electrode assembly according to some embodiments of the present application.

[0153] As shown in Figure 10, the electrode assembly manufacturing system 90 of the embodiment of the present application includes a supplying device 91 and a winding device 92. The supplying device 91 is used to supply a first polar sheet, a second polar sheet, a first separator, and a second separator. The winding device 92 is used to wind the first polar sheet, the second polar sheet, and the first separator along the winding direction and to form a folded region. The polarities of the first polar sheet and the second polar sheet are opposite, the first separator is used to separate the first polar sheet and the second polar sheet, the second separator is provided in the folded region and is stacked with the first separator and is used to separate adjacent first polar sheets and second polar sheets, at least some of the ions detached from the first polar sheet pass through the first separator and the second separator and are inserted into the second polar sheet.

[0154] The relevant structures of the electrode assemblies manufactured by the above manufacturing system can be referenced from the electrode assemblies provided in each of the above embodiments.

[0155] Furthermore, the embodiments and features described herein can be combined with each other, as long as they do not contradict each other.

[0156] The final points to be explained are as follows: The above embodiments are merely for the purpose of illustrating the technical solutions of the present application and do not limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand the following: Those skilled in the art can still modify the technical solutions described in the above embodiments or substitute some of their technical features, but such modifications or substitutions will not cause the substance of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. It includes a first polarity sheet, a second polarity sheet, and a first separator. The polarities of the first polar sheet and the second polar sheet are opposite, the first separator is used to separate the first polar sheet and the second polar sheet, and the first polar sheet, the second polar sheet and the first separator are wound along the winding direction. The electrode assembly has a bent region and a flat region connected to the bent region, a second separator is continuously provided only in part of the bent region and the flat region, both ends of the second separator along the winding direction are located in the flat region, the second separator is stacked with the first separator and used to separate adjacent first polar sheets and second polar sheets, the second separator is attached to the outer surface of the second polar sheet, at least some of the ions detached from the first polar sheet pass through the first separator and the second separator and are inserted into the second polar sheet. A plurality of the second separators are provided in the bending region, and adjacent second separators are separated by the first polarity sheet or the second polarity sheet. An electrode assembly in which, of the adjacent second separators, the thickness of the inner second separator is greater than the thickness of the outer second separator.

2. The electrode assembly according to claim 1, wherein the thickness of the second separator is greater than the thickness of the first separator.

3. The electrode assembly according to claim 1 or 2, wherein the second separator includes a plurality of separation layers stacked in the thickness direction of the second separator.

4. The electrode assembly according to claim 3, wherein adjacent separation layers are bonded to each other.

5. The plurality of separation layers include a first separation layer and a second separation layer installed adjacent to each other, the first separation layer being located between the second separation layer and the first separator. The electrode assembly according to claim 3 or 4, wherein, in the winding direction, the end of the second separation layer is offset from the end of the first separation layer.

6. The electrode assembly according to claim 5, wherein in the winding direction, both ends of the second separation layer extend beyond the first separation layer and are attached to the second polarity sheet.

7. The electrode assembly according to claim 6, wherein the entire first separation layer is located in the bending region, and both ends of the second separation layer along the winding direction are located in the flat region.

8. The electrode assembly according to any one of claims 3 to 7, wherein the material of the separation layer is the same as the material of the first separator, and the thickness of the separation layer is equal to the thickness of the first separator.

9. The electrode assembly according to any one of claims 1 to 8, wherein the porosity of the second separator is greater than or equal to the porosity of the first separator.

10. The electrode assembly according to any one of claims 1 to 9, wherein the second separator is provided within the bending region, at least between the innermost adjacent first polar sheet and the second polar sheet.

11. The electrode assembly according to any one of claims 1 to 10, wherein the second polarity sheet is a negative electrode sheet, and the second separator is attached to the outer surface of the second polarity sheet.

12. A battery cell comprising an outer case and an electrode assembly according to any one of claims 1 to 11 housed within the outer case.

13. A battery comprising a plurality of battery cells according to claim 12.

14. A power consumption device comprising a battery cell according to claim 12 for supplying electrical energy.

15. The steps include providing a first polarity sheet, a second polarity sheet, a first separator, and a second separator. The process includes the steps of winding the first polar sheet, the second polar sheet, and the first separator along the winding direction, and forming a folded region and a flat region connected to the folded region, The polarities of the first polar sheet and the second polar sheet are opposite, the first separator is used to separate the first polar sheet and the second polar sheet, the second separator is continuously provided only in the folded region and a portion of the flat region, both ends of the second separator along the winding direction are located in the flat region, the second separator is laminated with the first separator and is used to separate adjacent first polar sheets and second polar sheets, the second separator is attached to the outer surface of the second polar sheet, and at least some of the ions detached from the first polar sheet pass through the first separator and the second separator and are inserted into the second polar sheet. A plurality of the second separators are provided in the bending region, and adjacent second separators are separated by the first polarity sheet or the second polarity sheet. A method for manufacturing an electrode assembly, wherein the thickness of the inner second separator is greater than the thickness of the outer second separator among adjacent second separators.

16. A dispensing apparatus used to provide a first polarity sheet, a second polarity sheet, a first separator, and a second separator, The winding device includes a winding device used to wind the first polar sheet, the second polar sheet, and the first separator along the winding direction, and to form a folded region and a flat region connected to the folded region, The polarities of the first polar sheet and the second polar sheet are opposite, the first separator is used to separate the first polar sheet and the second polar sheet, the second separator is continuously provided only in the folded region and a portion of the flat region, both ends of the second separator along the winding direction are located in the flat region, the second separator is laminated with the first separator and is used to separate adjacent first polar sheets and second polar sheets, the second separator is attached to the outer surface of the second polar sheet, and at least some of the ions detached from the first polar sheet pass through the first separator and the second separator and are inserted into the second polar sheet. A plurality of the second separators are provided in the bending region, and adjacent second separators are separated by the first polarity sheet or the second polarity sheet. A manufacturing system for an electrode assembly in which, of the adjacent second separators, the thickness of the inner second separator is greater than the thickness of the outer second separator.

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