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

Abstract

To provide an electrode assembly in which the safety of a battery is improved by reducing or avoiding lithium deposition, a battery cell, a battery, and a manufacturing method and device of the electrode assembly.SOLUTION: An electrode assembly, a battery cell, a battery, a manufacturing method and device of the electrode assembly are disclosed. The electrode assembly comprises a positive electrode polar plate and a negative electrode polar plate. A folding region is formed in which the positive electrode polar plate and the negative electrode polar plate are wound / laminated and which has a barrier layer. A part of the barrier layer is positioned between adjacent positive electrode polar plate and negative electrode polar plate, to inhabit insertion of part of ions separated from the positive electrode polar plate into the negative electrode polar plate in the folding region. According to the above technical idea, the provision of the barrier layer between the adjacent positive electrode polar plate and negative electrode polar plate in the folding region can prevent the insertion of part of the ions separated from the positive active material into a negative active material layer in the folding region of the negative electrode polar plate adjacent to the positive electrode polar plate, thereby reducing the generation of lithium deposition to improve the safety of the battery cell and extend the life of the battery cell.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Rechargeable batteries, also known as secondary batteries, are batteries that can be used continuously by activating the active material through charging after discharging. Rechargeable batteries are widely used in electronic devices such as mobile phones, notebook computers, electric bicycles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and electric tools.

[0003] Rechargeable batteries may include nickel cadmium batteries, nickel hydrogen batteries, lithium ion batteries, secondary alkaline zinc manganese batteries, and the like.

[0004] Currently, the batteries widely used in automobiles are generally lithium-ion batteries. As rechargeable batteries, lithium-ion batteries have the advantages of small volume, high energy density, high power density, many usage cycles, and long storage life.

[0005] The rechargeable battery comprises an electrode assembly and an electrolyte solution, the electrode assembly comprising a positive electrode plate, a negative electrode plate, and a separator located between the positive electrode plate and the negative electrode plate, the positive electrode plate may be called a negative electrode plate, and both of the two surfaces of the positive electrode plate have a positive electrode active material layer, for example, the positive electrode active material of the positive electrode active material layer may be lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate, or lithium nickel cobalt manganese oxide, and the negative electrode plate may be called a positive electrode plate, and both of the two surfaces of the negative electrode plate have a negative electrode active material layer, for example, the negative electrode active material of the negative electrode active material layer may be graphite or silicon. Summary of the Invention [Problem to be solved by the invention]

[0006] Lithium deposition is a common abnormal phenomenon in lithium batteries, which affects the charging efficiency and energy density of lithium ions. When lithium deposition is severe, lithium crystals will also form, which can pierce and break the separator, causing internal short circuits and thermal runaway, seriously compromising the safety of the battery.

[0007] Therefore, how to reduce or avoid lithium deposition to improve the safety of batteries has become a challenging issue in the industry. [Means for solving the problem]

[0008] According to various aspects of the present application, there are provided electrode assemblies, battery cells, batteries, and methods and apparatus for manufacturing electrode assemblies that overcome or at least partially alleviate the above problems.

[0009] According to a first aspect of the present application, there is provided an electrode assembly, comprising a positive electrode plate and a negative electrode plate, the positive electrode plate and the negative electrode plate being wound or stacked to form a folding region; The bent region has a barrier layer, at least a portion of which is located between the adjacent positive and negative plates and is used to prevent at least a portion of the ions desorbed from the positive plate from being inserted into the negative plate in the bent region. By providing a barrier layer between the adjacent positive and negative plates, at least a portion of the ions desorbed from the positive active material layer of the positive plate in the bent region are blocked by the barrier layer during charging, and the ions blocked by the barrier layer cannot be inserted into the negative active material layer in the bent region of the negative plate adjacent to the positive plate. When the negative active material falls off of the negative plate, the occurrence of lithium precipitation is reduced, the safety of the battery cell is improved, and the life of the battery cell is extended.

[0010] In some embodiments, the electrode assembly further comprises a separator for separating adjacent positive and negative plates, and a barrier layer is attached to one or both surfaces of the positive plate and / or a barrier layer is attached to one or both surfaces of the negative plate and / or a barrier layer is attached to one or both surfaces of the separator, thus reducing the positional shift of the barrier layer during use of the electrode assembly.

[0011] In some embodiments, the electrode assembly further comprises a separator for separating adjacent positive and negative plates, and the barrier layer is disposed independently between the adjacent positive plates and the separator in the folded region, or the barrier layer is disposed independently between the adjacent negative plates and the separator in the folded region, thus facilitating attachment of the barrier layer.

[0012] In some embodiments, the porosity of the barrier layer is less than the porosity of the separator, thus allowing the barrier layer to more effectively block the passage of lithium ions.

[0013] In some embodiments, the electrode assembly includes one positive electrode plate and one negative electrode plate, and the one positive electrode plate and the one negative electrode plate are compressed and then wound to form a wound structure, and there is a barrier layer between at least the innermost adjacent positive electrode plate and the negative electrode plate in the folding region, thus reducing the lithium precipitation phenomenon between the innermost adjacent positive electrode plate and the negative electrode plate, and improving safety.

[0014] In some embodiments, the innermost plate in the folded region is the negative plate, thus improving the utilization of the active material in the positive plate.

[0015] In some embodiments, the barrier layer is discontinuous, and the discontinuous barrier layers are distributed at intervals along the folding direction, or the discontinuous barrier layers are distributed at intervals along a direction perpendicular to the folding direction, thereby preventing the passage of some lithium ions and reducing the occurrence of lithium precipitation, as well as ensuring the energy density of the electrode assembly.

[0016] In some embodiments, the thickness of the barrier layer is 2-200 microns, or 5-100 microns, thus not only ensuring the safety of the electrode assembly, but also ensuring the energy density of the electrode assembly.

[0017] In some embodiments, the barrier layer has at least one through hole.

[0018] In some embodiments, the porosity of the barrier layer is 10%-70%, or 20%-60%, so as to ensure not only the safety of the electrode assembly, but also the energy density of the electrode assembly.

[0019] In some embodiments, the thickness of the barrier layer is A microns, the porosity of the barrier layer is B, and A and B satisfy the relationship 3.5 microns≦A / B≦2000 microns, or 7 microns≦A / B≦1000 microns. In this way, not only can the safety of the electrode assembly be ensured, but also the energy density of the electrode assembly can be ensured.

[0020] In some embodiments, both ends of the negative active material layer of the negative plate perpendicular to the folding direction exceed the corresponding ends of the positive active material layer of the positive plate, thereby ensuring the energy density of the electrode assembly.

[0021] In some embodiments, the barrier layer has both ends along a direction perpendicular to the folding direction, and one or both ends of the barrier layer exceed the positive electrode active material layer of the positive electrode plate, thus preventing the passage of many lithium ions and reducing the occurrence of lithium precipitation.

[0022] In some embodiments, the barrier layer has both ends along a direction perpendicular to the folding direction, and the negative electrode active material layer of the negative electrode plate extends beyond one or both ends of the barrier layer, thereby preventing some lithium ions from passing through and reducing the occurrence of lithium precipitation, as well as ensuring the energy density of the electrode assembly.

[0023] In some embodiments, the barrier layer and the negative electrode plate are provided at the portion of maximum curvature facing each other, so that no or only a small amount of lithium ions are inserted into the portion of maximum curvature, thereby reducing the occurrence of lithium deposition.

[0024] In some embodiments, the barrier layer comprises at least one of an inorganic oxide, a binder, and a tape.

[0025] In some embodiments, both ends of the barrier layer extending along the folding direction are located in the folding region, thus preventing the passage of many lithium ions and reducing the occurrence of lithium deposition.

[0026] In some embodiments, the electrode assembly includes a flat region connected to the folded region; One end of the barrier layer extending along the folding direction is located in a flat region and the other end is located in a folding region, or both ends of the barrier layer extending along the folding direction are located in flat regions.

[0027] According to a second aspect of the present application, there is provided a battery cell, comprising a housing, a cover plate and at least one electrode assembly according to any one of the above embodiments, The housing has a chamber and an opening, and the electrode assembly is accommodated in the chamber; The cover plate is used to seal the opening in the housing.

[0028] According to a third aspect of the present application, there is provided a battery, comprising a housing and at least one battery cell, the battery cell contained within the housing.

[0029] According to a fourth aspect of the present application, there is provided a method for manufacturing an electrode assembly, comprising: providing a positive electrode plate, a negative electrode plate and a barrier layer; and a step of winding or stacking the positive and negative plates to form a fold region, the fold region having a barrier layer, at least a portion of the barrier layer being located between adjacent positive and negative plates and used to prevent at least a portion of ions desorbing from the positive plate from being inserted into the negative plate in the fold region.

[0030] In some embodiments, a separator is provided to separate adjacent positive and negative plates, and the separator, positive and negative plates are wound or stacked together.

[0031] In some embodiments, prior to winding or stacking the separator, positive plate and negative plate together, the method further includes providing a barrier layer on one or two surfaces of the positive plate or the negative plate.

[0032] In some embodiments, providing a barrier layer on one or two surfaces of the positive or negative electrode plate specifically includes applying or coating the barrier layer on one or two surfaces of the positive or negative electrode plate.

[0033] According to a fifth aspect of the present application, there is provided an apparatus for manufacturing an electrode assembly, comprising: A first providing device for providing a positive electrode plate; A second providing device for providing a negative electrode plate; a third providing device for providing a barrier layer; and an assembly device for winding or stacking the positive electrode plate and the negative electrode plate to form a folding region; The folding region has a barrier layer, at least a portion of which is located between adjacent positive and negative electrode plates and is used to prevent at least a portion of the ions desorbed from the positive electrode plate from being inserted into the negative electrode plate in the folding region.

[0034] In some embodiments, the electrode assembly manufacturing equipment further includes a fourth providing device for providing a separator for separating adjacent positive and negative electrode plates, and the assembly device is further used for winding or stacking the positive electrode plates, the negative electrode plates, and the separator to form the folding region.

[0035] In some embodiments, there are two third providing devices, and the two third providing devices are used to provide a barrier layer respectively and attach or coat the barrier layer on two surfaces of the positive electrode plate or the negative electrode plate.

[0036] According to a sixth aspect of the present application, there is provided a power consuming device, the power consuming device being configured to receive power provided by a battery.

[0037] The above description is merely an outline of the technical solutions of the embodiments of the present application, which can be implemented in accordance with the contents of the specification in order to more clearly understand the technical means of the embodiments of the present application. In order to make the above and other objectives, features and advantages of the embodiments of the present application more obvious and understandable, specific embodiments of the present application are described below as examples. [Brief description of the drawings]

[0038] In order to more clearly describe the technical solutions of the embodiments of the present application, the following will briefly describe the drawings that need to be used in the description of the embodiments. It will be apparent that the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative labor.

[0039] [Figure 1] 1 is a schematic perspective view of an electrode assembly according to an embodiment of the present application; [Diagram 2]2 is a structural schematic diagram of a cross section taken along a direction perpendicular to a winding axis K of the electrode assembly of FIG. 1. FIG. [Diagram 3] 4 is a schematic diagram of a partial structure of a bending region of an electrode assembly according to an embodiment of the present application; [Figure 4] FIG. 13 is a structural schematic diagram of a barrier layer distribution after unfolding of a bending region of an electrode assembly according to another embodiment of the present application. [Diagram 5] FIG. 13 is a structural schematic diagram of another barrier layer distribution after unfolding of the bending region of the electrode assembly according to another embodiment of the present application. [Figure 6] FIG. 13 is a structural schematic diagram of another barrier layer distribution after unfolding of the bending region of the electrode assembly according to another embodiment of the present application. [Figure 7] FIG. 4 is a structural schematic diagram of a negative electrode plate according to another embodiment of the present application. [Figure 8] FIG. 4 is a structural schematic diagram of a positive electrode plate in another embodiment of the present application. [Figure 9] FIG. 9 is a schematic cross-sectional view of the AA direction in FIG. [Figure 10] 9 is a schematic cross-sectional view of the structure taken along the line BB in FIG. 8. [Figure 11] 13 is a structural schematic diagram of a cross section perpendicular to the winding axis of a flat electrode assembly according to another embodiment of the present application. FIG. [Figure 12] 13 is a structural schematic diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. FIG. [Figure 13] 13 is a structural schematic diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. FIG. [Figure 14] 13 is a structural schematic diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. FIG. [Figure 15] 13 is a structural schematic diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. FIG. [Figure 16] 13 is a structural schematic diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. FIG. [Figure 17]13 is a structural schematic diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. FIG. [Figure 18] 13 is a structural schematic diagram of a cross section perpendicular to the winding axis of a flat electrode assembly according to another embodiment of the present application. FIG. [Figure 19] 13 is a structural schematic diagram of a cross section perpendicular to the winding axis of a flat electrode assembly according to another embodiment of the present application. FIG. [Figure 20] FIG. 4 is a structural schematic diagram of a battery cell according to another embodiment of the present application. [Figure 21] FIG. 4 is a structural schematic diagram of a battery module according to another embodiment of the present application. [Figure 22] FIG. 2 is a structural schematic diagram of a battery according to another embodiment of the present application. [Diagram 23] FIG. 2 is a structural schematic diagram of a power consumption device according to another embodiment of the present application; [Figure 24] 4 is a schematic flowchart of a method for manufacturing an electrode assembly according to another embodiment of the present application. [Diagram 25] 2 is a structural schematic diagram of an electrode assembly manufacturing equipment according to another embodiment of the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described below clearly and completely with reference to the drawings of the embodiments of the present application, and it is obvious that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. Based on the embodiments of the present application, all other embodiments that a person skilled in the art can obtain without creative labor fall within the scope of protection of the present application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art, and the terms used herein in the specification of the application are intended to merely describe certain embodiments, but are not intended to limit the application, and the terms "comprises," "has," and any variations thereof in the specification, claims, and brief description of the drawings of the application above are intended to cover a non-exclusive inclusion.

[0042] In this specification, reference to an "embodiment" means that a particular feature, structure, or characteristic described with reference to the embodiment may be included in at least one embodiment of the present application. The appearance of such a phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. As can be understood explicitly and implicitly by those skilled in the art, the embodiments described in this specification can be combined with other embodiments.

[0043] In this specification, the term "and / or" is merely intended to describe a relation between related objects and indicates that three types of relations may exist, for example, A and / or B may indicate three cases: when only A is present, when both A and B are present, and when only B is present. Also, in this specification, the character " / " generally indicates that the related objects before and after have an "or" relationship.

[0044] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are orientations or positional relationships based on the drawings, and are merely intended to easily and simply describe the present application, and do not indicate or imply that such devices or elements necessarily have a specific orientation or are constructed and operated in a specific orientation, and therefore should not be understood as limiting the present application. In addition, the terms "first", "second", etc. in the specification, claims, or the above drawings of the present application are used to distinguish different objects, but are not intended to describe a specific order, and may explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, "plurality" means two or more.

[0045] In the description of the present application, it is necessary to explain that unless otherwise clearly specified and limited, the terms "attached", "coupled" and "connected" should be understood in a broad sense, for example, may be fixedly connected, detachably connected or integrally connected, may be mechanically connected, may be electrically connected, may be directly connected, may be indirectly connected through an intermediate medium, may be internally communicated between two elements. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific situation.

[0046] In order to reduce the volume of the lithium ion battery and increase the energy density, the positive electrode plate, the negative electrode plate and the separator of the electrode assembly of the lithium ion battery may be wound and then compressed. For example, as shown in Fig. 1, which is a perspective structural schematic diagram of an electrode assembly, the electrode assembly includes a negative electrode plate, a positive electrode plate and a separator, and the negative electrode plate, the positive electrode plate and the separator are stacked and then wound around a winding axis K to form a winding structure, the separator is an insulating film, which is used to separate the negative electrode plate and the positive electrode plate and prevent a short circuit between the negative electrode plate and the positive electrode plate, the winding structure of the electrode assembly is a flat body shape, and the cross-sectional structural schematic diagram of the electrode assembly along a direction perpendicular to the winding axis K is shown in Fig. 2.

[0047] 1 and 2, the electrode assembly includes a flat region 100 and folded regions 200 located at both ends of the flat region 100. The flat region 100 is a region having a parallel structure of the wound structure, that is, the negative electrode plate 101, the positive electrode plate 102, and the separator 103 in the flat region 100 are approximately parallel to each other, that is, the surfaces of the negative electrode plate 101, the positive electrode plate 102, and the separator 103 of each layer in the flat region 100 of the electrode assembly are all flat. The folding region 200 is a region having a folding structure of the winding structure, i.e., the negative electrode plate 101, the positive electrode plate 102 and the separator 103 in the folding region 200 are all folded, i.e., the surfaces of the negative electrode plate 101, the positive electrode plate 102 and the separator 103 of each layer in the folding region 200 of the electrode assembly are all curved, and the folding region 200 has a folding direction L, which may be understood as the direction in which the surface of the electrode assembly points to a flat region along the folding region, for example, the folding direction L is along the winding direction of the winding structure in the folding region 200.

[0048] The surface of the negative electrode plate 101 has a negative electrode active material layer made of a negative electrode active material, and the surface of the positive electrode plate 102 has a positive electrode active material layer made of a positive electrode active material. For example, the positive electrode active material may be lithium manganate, lithium cobalt oxide, lithium iron phosphate, or lithium nickel cobalt manganate, and the negative electrode active material may be graphite or silicon.

[0049] During charging of a lithium-ion battery, lithium ions are released from the positive electrode and inserted into the negative electrode. However, some abnormal situations may occur, such as insufficient lithium insertion space in the negative electrode, too large resistance to lithium ion insertion into the negative electrode, or too fast release of lithium ions from the positive electrode, so that the released lithium ions cannot be inserted into the negative electrode active material layer of the negative electrode plate in equal amounts, and the lithium ions that cannot be inserted into the negative electrode plate can only obtain electrons on the surface of the negative electrode, resulting in the formation of silver-white metallic lithium elements, which is the lithium precipitation phenomenon. Lithium precipitation not only reduces the performance of the lithium-ion battery and significantly shortens the cycle life, but also limits the fast charging capacity of the lithium-ion battery. In addition, when lithium precipitation occurs in a lithium-ion battery, the precipitated lithium metal is highly active and can react with the electrolyte at a low temperature, leading to a decrease in the self-heating onset temperature (Tonset) of the battery and an increase in the self-heating rate, which seriously impairs the safety of the battery. In addition, if the lithium deposition is serious, the desorbed lithium ions can form lithium crystals on the surface of the negative electrode plate, and the lithium crystals are prone to pierce and break the separator, causing a risk of short circuit between the adjacent positive and negative electrodes.

[0050] During the research and development process, the inventor found that lithium deposition often occurs in the bent region of the electrode assembly, and after further research, the inventor found that the lithium deposition is caused by the loss of active material, the main reason being that the negative active material is applied to the surface of the negative plate, the positive active material is applied to the surface of the positive plate, and the positive and negative plates located in the curved region need to be folded, which may cause the active materials to fall off, which is called the dusting phenomenon, and in particular, the innermost plate in the folded region is the most bent and is more likely to fall off the active material. The loss of active material, especially the loss of the active material from the negative plate, may cause the lithium insertion site of the negative active material layer of the negative plate to be less than the number of lithium ions that can be provided by the positive active material layer of the adjacent positive plate, and therefore the lithium deposition phenomenon is likely to occur when the lithium battery is charged.

[0051] In view of the above, the present application provides an electrode assembly, the electrode assembly comprising a negative electrode plate, a positive electrode plate and a separator, the negative electrode plate, the positive electrode plate and the separator may be stacked and then wound around a winding axis, for example, a flat-body wound structure may be formed, the negative electrode plate, the positive electrode plate and the separator may be stacked and then continuously folded in a Z-shape, whether the electrode assembly is formed by winding or by continuously folding in a Z-shape, the electrode assembly comprises a flat region and a folded region connected to both ends of the flat region, and any adjacent positive electrode plate of the folded region may be folded in a Z-shape to reduce or avoid lithium deposition. A barrier layer is provided between a positive electrode plate and a negative electrode plate, in particular between adjacent positive electrode plate and negative electrode plate on the innermost side of the folding region, and the barrier layer is used to block at least a portion of lithium ions desorbed from the positive electrode active material layer of the positive electrode plate in the folding region, so that the ions blocked by the barrier layer cannot be inserted into the negative electrode active material layer of the negative electrode plate adjacent to the positive electrode plate in the folding region, and the number of lithium insertion sites in the negative electrode active material layer of the negative electrode plate in the folding region is approximately the same as the number of lithium ions that can be provided by the positive electrode active material layer of the positive electrode plate adjacent thereto, and therefore the occurrence of lithium precipitation can be reduced or avoided.

[0052] Regardless of whether the electrode assembly is formed by winding or by continuously folding in a Z-shape, the electrode assembly comprises a flat region and folding regions connected to both ends of the flat region. For the sake of simplicity, the electrode assembly in this embodiment is described using a flat body winding structure as an example. For example, the structure of one folding region C and flat region P of the flat body winding structure may be shown in FIG. 3, which is a schematic diagram of a partial structure of the folding region of the electrode assembly according to one embodiment of the present application. The electrode assembly comprises a positive electrode plate 1, a negative electrode plate 2, and a separator 3 for separating the positive electrode plate 1 and the negative electrode plate 2 in the folding region C. The separator 3 may be independently disposed between the adjacent positive electrode plate 1 and negative electrode plate 2, or may be coated on the surface of the positive electrode plate 1 or the negative electrode plate 2.

[0053] The separator 3 has electronic insulation properties and is used to separate the adjacent positive electrode plate 1 and negative electrode plate 2 and prevent short-circuiting between the adjacent positive electrode plate 1 and negative electrode plate 2. The separator 3 has a large number of through-holes, which can ensure the free passage of electrolyte ions and has excellent permeability to lithium ions, so that the separator 3 basically cannot block the passage of lithium ions. For example, the separator 3 includes a separator substrate layer and a functional layer located on the surface of the separator substrate layer, and the separator substrate layer may be at least one of polypropylene, polyethylene, ethylene-propylene copolymer, polybutylene terephthalate, etc., and the functional layer may be a mixture layer of a ceramic oxide and a binder.

[0054] In the embodiment of the present application, the electrode assembly further has a barrier layer 4 in the folding region C, and at least a portion of the barrier layer 4 is located between adjacent positive electrode plate 1 and negative electrode plate 2 and is used to prevent at least a portion of the ions detached from the positive electrode plate 1 from being inserted into the negative electrode plate 2 in the folding region C.

[0055] By providing the barrier layer 4 between the adjacent positive electrode plate 1 and negative electrode plate 2 in the bending region C, the lithium precipitation phenomenon can be effectively reduced or avoided. By providing the barrier layer 4 between the adjacent positive electrode plate 1 and negative electrode plate 2, at least a part of the ions desorbed from the positive electrode active material layer (for example, the positive electrode active material layer in the bending region C) of the positive electrode plate 1 during charging is blocked by the barrier layer 4, and the ions blocked by the barrier layer 4 cannot be inserted into the negative electrode active material layer in the bending region C of the negative electrode plate 2, and the occurrence of lithium precipitation is reduced when the negative electrode active material falls off from the negative electrode plate 2. That is, even though the lithium insertion site of the negative electrode plate 2 is reduced due to the fall-off of the negative electrode active material, the barrier layer 4 blocks at least a part of the lithium ions desorbed from the positive electrode plate 1 adjacent to the negative electrode plate 2, so that the occurrence of lithium precipitation can be reduced or avoided.

[0056] In another embodiment of the present application, the material of the barrier layer 4 may include inorganic oxide and / or polymer, so that the barrier layer 4 can prevent the passage of lithium ions.

[0057] In another embodiment of the present application, the inorganic oxide can be at least one of magnesium oxide (MgO), calcium oxide (CaO), boehmite, wollastonite, barium sulfate (BaSO), calcium sulfate (CaSO), calcium carbonate (CaCO), alumina (AlO), and silica (SiO).

[0058] In another embodiment of the present application, the polymer may be at least one of polypropylene, polyvinyl chloride (PVC), polyethylene (PE), epoxy resin, polyacrylate, and polyurethane rubber.

[0059] In another embodiment of the present application, the barrier layer 4 may be a tape or an adhesive tape. The tape includes an adhesive and a substrate, and the substrate material may include polyethylene and / or Ethylene Vinyl Acetate Copolymer (EVA). The adhesive tape material may include at least one of polyethylene phthalate, polyvinylidene fluoride, polyurethane, sodium polyacrylate, styrene butadiene rubber, polyetherimide, carboxymethyl cellulose, and acrylate.

[0060] In another embodiment of the present application, one positive electrode plate 1 and one negative electrode plate 2 may be stacked and then rolled or folded, or at least one (e.g., two or more) positive electrode plate 1 and at least one (e.g., two or more) negative electrode plate 2 may be stacked and then rolled or folded to form a folding region C. When the electrode assembly has multiple layers of positive electrode plates 1 and multiple layers of negative electrode plates 2 in the folding region C, the folding region C has a structure in which the positive electrode plates 1 and the negative electrode plates 2 are alternately distributed, and a barrier layer 4 is provided between at least one adjacent layer of the positive electrode plate 1 and the negative electrode plate 2. The adjacent positive electrode plate 1 and the negative electrode plate 2 in the folding region C means that one layer of the positive electrode plate 1 and one layer of the negative electrode plate 2 are adjacent to each other in the folding region C, and another layer of the positive electrode plate 1 or another layer of the negative electrode plate 2 is not provided between them.

[0061] In another embodiment of the present application, in addition to the folding region C having a structure in which the positive electrode plates 1 and the negative electrode plates 2 are alternately distributed, the folding region C (e.g., the innermost and / or outermost portions of the folding region C) may further have a structure in which there is no negative electrode plate 2 between two adjacent layers of positive electrode plates 1, or a structure in which there is no positive electrode plate 1 between two adjacent layers of negative electrode plates 2, in which case a barrier layer 4 may be provided between the two adjacent layers of positive electrode plates 1 or the two adjacent layers of negative electrode plates 2, i.e., the barrier layer 4 is provided between adjacent positive electrode plates 1 and negative electrode plates 2.

[0062] In another embodiment of the present application, the electrode assembly generally has the largest degree of folding of the innermost plate in the folding region C, i.e., the probability of active material falling off of the innermost plate is the highest or the active material falling off is the most serious, and the innermost plate may be the positive electrode plate 1 or the negative electrode plate 2. For example, when the innermost plate is the negative electrode plate 2, there is a barrier layer 4 between at least the innermost adjacent positive electrode plate 1 and the negative electrode plate 2 in the folding region C in order to reduce the occurrence of lithium deposition as much as possible. In this way, the lithium deposition phenomenon between the innermost adjacent positive electrode plate and the negative electrode plate can be reduced, and safety can be improved. When the innermost plate in the folding region C is the negative electrode plate 2, the utilization efficiency of the active material of the positive electrode plate 1 can be improved.

[0063] The barrier layer 4 is located between the adjacent positive electrode plate 1 and the negative electrode plate 2, the barrier layer 4 may be independently located between the adjacent positive electrode plate 1 and the negative electrode plate 2, or the barrier layer 4 may be attached to any surface of the positive electrode plate 1, the negative electrode plate 2, or the separator 3. The barrier layer 4 may be independently located between the adjacent positive electrode plate 1 and the negative electrode plate 2, which means that the barrier layer 4 is laminated to be separated from the positive electrode plate 1 and the negative electrode plate 2, respectively, that is, there is no adhesion or coating relationship, which is advantageous for the attachment of the barrier layer 4, and the attachment means adhesion or coating or spray coating, and the attachment can reduce the position movement of the barrier layer 4 during the use of the battery cell.

[0064] For example, a barrier layer 4 is attached to one or both surfaces of a positive electrode plate 1 and / or a barrier layer 4 is attached to one or both surfaces of a negative electrode plate 2 .

[0065] In another embodiment of the present application, the barrier layer 4 is independently disposed between adjacent positive electrode plates 1 and separators 3 in the folding region C, or the barrier layer 4 is independently disposed between adjacent negative electrode plates 2 and separators 3 in the folding region C, or the barrier layer 4 is attached to one surface or two surfaces of the separator 3. The barrier layer 4 is independently disposed between adjacent positive electrode plates 1 and separators 3 in the folding region C, or the barrier layer 4 is independently disposed between adjacent negative electrode plates 2 and separators 3 in the folding region C, which are laminated such that the barrier layer 4 is separated from the positive electrode plates 1, the negative electrode plates 2 and the separators 3, respectively, i.e., there is no adhesive or coating relationship.

[0066] In another embodiment of the present application, both ends of the barrier layer 4 extending along the folding direction L are located in the folding region C, i.e., the entire barrier layer 4 is located in the folding region C. In this embodiment, the electrode assembly further includes a flat region P connected to the folding region C, the folding direction L is a direction along the curved surface of the folding region C and pointing to the flat region P, and the direction perpendicular to the folding direction L is a direction perpendicular to the folding direction L.

[0067] In another embodiment of the present application, one end of the barrier layer 4 extending along the folding direction L is located in the flat region P, and the other end is located in the folding region C.

[0068] In another embodiment of the present application, in order to block as many lithium ions as possible, the barrier layer 4 has as large an area as possible in the folding region C, for example, both ends of the barrier layer 4 extending along the folding direction L are located in the flat region P, that is, the barrier layer 4 is not only located in the folding region C, but also extends into the flat region P.

[0069] In another embodiment of the present application, both ends of the barrier layer 4 extending along the folding direction L are located at the boundary between the folding region C and the flat region P, or both ends of the barrier layer 4 extending along the folding direction L are close to the boundary between the folding region C and the flat region P.

[0070] In another embodiment of the present application, for adjacent positive and negative plates 1 and 2, when the negative plate 2 is located at the innermost part of the folding region C, the detachment of the negative active material from the part of the innermost negative plate 2 with the largest curvature is most serious, and therefore, regardless of how the barrier layer 4 extends along the folding direction L, the barrier layer 4 prevents lithium ions detached from the positive plate 1 from being inserted into the part of the negative plate 2 with the largest curvature as much as possible, i.e., the barrier layer 4 is provided opposite the part of the negative plate 2 with the largest curvature and is used to cover the part of the negative plate 2 with the largest curvature. In this way, lithium ions are not inserted or only slightly inserted into the part of the negative plate 2 with the largest curvature, thereby reducing the occurrence of lithium precipitation.

[0071] In another embodiment of the present application, the portion of the innermost negative electrode plate 2 in the folding region C with the largest curvature is a line perpendicular to the folding direction L on the curved surface of the innermost negative electrode plate 2 in the folding region C (e.g., the line may be a straight line), and the curvature of any point on the line is larger than the curvature of the curved surface of the innermost negative electrode plate 2 in the folding region C on both sides of the folding direction L of the point. For example, when the negative electrode plate 2 is folded symmetrically along the folding direction L in the folding region C, the portion of the innermost negative electrode plate 2 in the folding region C with the largest curvature is the middle portion of the negative electrode plate 2 in the folding region C.

[0072] The larger the area of ​​the barrier layer 4 in the folding region C, the more lithium ions it can block; on the other hand, the more lithium ions that are blocked, the lower the energy density in the folding region C, and as a result, the lower the energy density of the electrode assembly. Therefore, in another embodiment of the present application, for the adjacent positive electrode plate 1 and negative electrode plate 2 in the folding region C, in order to ensure a predetermined energy density, lithium ions may be appropriately desorbed from the positive electrode plate 1 and inserted into the negative electrode plate 2.

[0073] For example, as shown in FIG. 4, which is a structural schematic diagram of the barrier layer distribution after the folding region C of the electrode assembly according to another embodiment of the present application is unfolded, the folding region C has a plurality of discontinuous barrier layers 4 between the adjacent positive electrode plate 1 and negative electrode plate 2, and the discontinuous barrier layers 4 are distributed at intervals along the folding direction L, so that some lithium ions are not blocked by the barrier layers 4, that is, some lithium ions pass between the two adjacent barrier layers 4 and are inserted into the negative electrode active material layer of the negative electrode plate 2. For example, the discontinuous barrier layers 4 are attached on the surface of the positive electrode plate 1. In this way, it is possible to not only block the passage of some lithium ions and reduce the occurrence of the lithium precipitation phenomenon, but also to ensure the energy density of the electrode assembly.

[0074] Also, for example, as shown in FIG. 5, it is a structural schematic diagram of another barrier layer distribution after unfolding the folding region of the electrode assembly according to another embodiment of the present application, in which a plurality of discontinuous barrier layers 4 are provided between adjacent positive electrode plate 1 and negative electrode plate 2 in the folding region, and the discontinuous barrier layers 4 are distributed at intervals along the K direction perpendicular to the folding direction L, so that some lithium ions are not blocked by the barrier layers 4, that is, some lithium ions pass between two adjacent barrier layers 4 and are inserted into the negative electrode active material layer of the negative electrode plate 2. For example, the discontinuous barrier layers 4 are attached on the surface of the positive electrode plate 1. The K direction perpendicular to the folding direction L can be the width direction of the positive electrode plate 1 and the negative electrode plate 2. When the electrode assembly has a winding structure, the K direction perpendicular to the folding direction L is the direction of the winding axis of the winding structure.

[0075] For example, as shown in FIG. 6, which is a structural schematic diagram of another barrier layer distribution after unfolding of the folding region of an electrode assembly according to another embodiment of the present application, a barrier layer 4 is attached on the surface of a positive electrode plate 1, and the barrier layer 4 has at least one through hole 41, which is used for allowing some lithium ions to pass through and be inserted into the negative electrode active material layer of the negative electrode plate 2.

[0076] In another embodiment of the present application, the porosity of the barrier layer 4 is less than that of the separator 3, so that the barrier layer 4 can more effectively block the passage of lithium ions. The porosity is the percentage of the volume of the pores in the bulk material to the total volume of the material in its natural state. Generally, the test method for the porosity is the true density test method.

[0077] In order to achieve a better balance between blocking lithium ions and maintaining energy density, the thickness of the barrier layer 4 is A microns, and the porosity of the barrier layer 4 is B, and A and B satisfy the relationship of 3.5 microns≦A / B≦2000 microns, optionally 7 microns≦A / B≦1000 microns. In this way, the safety of the electrode assembly can be ensured, as well as the energy density of the electrode assembly, and a better balance between safety and energy density can be achieved. If A is too small, it indicates that the thickness of the barrier layer 4 is too small, and lithium crystals are likely to pierce and break the barrier layer 4, and even pierce and break the separator 3, resulting in the lithium ion blocking effect of the barrier layer 4 being lost, which may cause safety risks; if B is relatively large, it indicates that the porosity of the barrier layer 4 is too large, and the larger the porosity of the barrier layer 4, the more lithium ions pass through the protective layer 4, which may result in serious lithium precipitation. For example, when A / B is less than 3.5, A is relatively small, i.e., the thickness of the barrier layer 4 is too small, and B is relatively large, i.e., the porosity of the barrier layer 4 is too large, which may cause the barrier layer 4 to lose its lithium ion blocking effect and create safety risks; when A / B is greater than 2000, A is relatively large, i.e., the thickness of the barrier layer 4 is too large, and B is relatively small, i.e., the porosity of the barrier layer 4 is too small, which may seriously impair the energy density of the battery cell.

[0078] For example, the thickness of the barrier layer 4 is 2-200 microns (um), optionally, the thickness of the barrier layer 4 is 5-100 microns, and further optionally, the thickness of the barrier layer 4 is 5-50 microns. In this way, the safety of the electrode assembly can be ensured, as well as the energy density of the electrode assembly, and a better balance between safety and energy density can be achieved. For example, if the thickness of the barrier layer 4 is less than 2 um, the thickness of the barrier layer 4 is too small, and when lithium deposition becomes serious, the lithium crystals may pierce the barrier layer 4 and even pierce the separator 3, resulting in the lithium ion blocking effect of the barrier layer 4 being lost, which may cause safety risks. If the thickness of the barrier layer 4 is greater than 500 um, the thickness of the barrier layer 4 is relatively large, resulting in too large a gap between the adjacent positive electrode plate 1 and the negative electrode plate 2, which may cause the barrier layer 4 to occupy space, which may impair the energy density of the electrode assembly, and also the gap between the two adjacent layers is too large, which may seriously impair the cycle characteristics.

[0079] The porosity of the barrier layer 4 is 10%-70%, and optionally the porosity of the barrier layer 4 is 20%-60%. In this way, the safety of the electrode assembly can be ensured as well as the energy density of the electrode assembly, and a better balance between safety and energy density can be achieved. For example, when the porosity is less than 10%, most or all of the lithium ions are blocked by the barrier layer 4 and cannot be inserted into the negative electrode plate 2, thereby impairing the energy density of the electrode assembly; when the porosity is greater than 70%, most or almost all of the lithium ions pass through the barrier layer 4, causing the risk of lithium precipitation, and as a result, the lithium crystals pierce and break the barrier layer 4, thereby eliminating the lithium ion blocking effect of the barrier layer 4 and causing safety risks.

[0080] When the electrode assembly has a wound structure, the width directions of the positive electrode plates 1 and the negative electrode plates 2 are parallel to the direction of the winding axis, and are parallel to the direction perpendicular to the folding direction L. When the electrode assembly does not have a wound structure, the width directions of the positive electrode plates 1 and the negative electrode plates 2 are parallel to the direction perpendicular to the folding direction L. For convenience of the following description, in this embodiment, the width directions of the positive electrode plates 1 and the negative electrode plates 2, the direction perpendicular to the folding direction L, and the direction of the winding axis are collectively referred to as the K direction.

[0081] The structure of the negative electrode plate 2 may be shown in FIG. 7, which is a structural schematic diagram of a negative electrode plate according to another embodiment of the present application. The negative electrode plate 2 includes a negative electrode main body portion 21 and a negative electrode tab portion 22 extending outward from the negative electrode main body portion 21 along the K direction. At least a portion of the surface of the negative electrode main body portion 21 along the K direction is a negative electrode active material region 211. The negative electrode active material region 211 is used for applying a negative electrode active material, and the negative electrode active material may be graphite or silicon.

[0082] In another embodiment of the present application, not only is a negative electrode active material region 211 provided in a portion of the surface of the negative electrode main body portion 21, but a negative electrode active material region 211 is also provided in a root region close to the negative electrode main body portion 21 on the surface of the negative electrode tab portion 22, i.e., a portion of the surface of the negative electrode tab portion 22 is a negative electrode active material region 211.

[0083] In another embodiment of the present application, as shown in FIG. 7, the negative electrode active material region 211 covers the entire surface of the negative electrode main body portion 21 along the direction K.

[0084] In another embodiment of the present application, the positive electrode active material may not cover the entire surface of the positive electrode plate 1, for example, as shown in FIG. 8, which is a schematic structural diagram of a positive electrode plate in another embodiment of the present application.

[0085] The positive electrode plate 1 comprises a positive electrode main body portion 11 and at least one positive electrode tab portion 12 extending to the outside of the positive electrode main body portion 11 along the K direction, and at least a portion of the surface of the positive electrode main body portion 11 is a positive electrode active material region 111. A positive electrode active material may be applied to the positive electrode active material region 111, and the positive electrode active material may be, for example, a ternary material, lithium manganate or lithium iron phosphate.

[0086] In another embodiment of the present application, the surface of the positive electrode main body portion 11 further includes a first insulating layer coated region 112 adjacent to the positive electrode active material region 111, and the first insulating layer coated region 112 is located on the side of the positive electrode active material region 111 adjacent to the positive electrode tab portion 12, and the first insulating layer coated region 112 is used for coating an insulating material and for insulating and separating the positive electrode active material region 111 and the positive electrode tab portion 12. For example, as shown in FIG. 9, which is a schematic cross-sectional structure diagram in the AA direction in FIG. 8, the positive electrode active material region 111 is provided on two surfaces of the current collector 10 of the positive electrode plate 1, the positive electrode tab portion 12 is a part of the current collector 10 of the positive electrode plate 1, and the material of the current collector 10 can be aluminum.

[0087] For example, the positive electrode active material region 111 and the first insulating layer coated region 112 are distributed on the surface of the positive electrode main body portion 11 at both ends along the width direction (i.e., the K direction) of the positive electrode main body portion 11, and the positive electrode tab portion 12 and the first insulating layer coated region 112 belong to the same end portion of the positive electrode main body portion 11.

[0088] In another embodiment of the present application, the positive electrode active material region 111 and the first insulating layer applied region 112 are two approximately parallel regions on the surface of the positive electrode main body portion 11, and are distributed in two layers on the surface of the positive electrode main body portion 11 along the K direction.

[0089] In another embodiment of the present application, the first insulating layer coating region 112 may be located at the portion where the positive electrode body portion 11 and the positive electrode tab portion 12 are connected to each other. For example, the first insulating layer coating region 112 is located at the portion where the positive electrode tab portion 12 is connected to each other on the surface of the positive electrode body portion 11, and is used to separate the surface of the positive electrode tab portion 12 from the positive electrode active material region 111. In another embodiment of the present application, not only is the first insulating layer coating region 112 provided on the surface of the positive electrode body portion 11, but a second insulating layer coating region 121 is also provided in the root region of the positive electrode tab portion 12 close to the positive electrode body portion 11, and the second insulating layer coating region 121 is used to coat an insulating material.

[0090] In another embodiment of the present application, an insulating material is applied to the surface of the first insulating layer application region 112, and the insulating material includes an inorganic filler and an adhesive. The inorganic filler includes one or more of boehmite, alumina, magnesium oxide, titanium dioxide, zirconium oxide, silica, silicon carbide, boron carbide, calcium carbonate, aluminum silicate, calcium silicate, potassium titanate, and barium sulfate. The binder includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyacrylic acid, polyacrylate, polyacrylic acid-acrylate, polyacrylonitrile-acrylic acid, and polyacrylonitrile-acrylate.

[0091] In another embodiment of the present application, each positive electrode plate 1 may have one or more positive electrode tab portions 12, and when the positive electrode plate 1 has two or more positive electrode tab portions 12, all of the positive electrode tab portions 12 are located on the same side of the positive electrode plate 1 along the K direction.

[0092] As shown in Figures 7 and 8, when the positive electrode plate 1 and the negative electrode plate 2 are stacked on each other, both ends of the negative electrode active material region 211 of the negative electrode plate 2 along the direction K exceed the corresponding ends of the positive electrode active material region 111 of the adjacent positive electrode plate 1, and thus the energy density of the electrode assembly can be ensured. For example, both ends of the negative electrode active material region 211 along the direction K are a first end 23 and a second end 24, and both ends of the positive electrode active material region 111 along the direction K are a third end 13 and a fourth end 14, respectively, the first end 23 of the negative electrode active material region 211 and the third end 13 of the positive electrode active material region 111 are located on the same side of the electrode assembly along the direction K, and the first end 23 of the negative electrode active material region 211 exceeds the third end 13 of the positive electrode active material region 111 along the direction K, the second end 24 of the negative electrode active material region 211 and the fourth end 14 of the positive electrode active material region 111 are located on the other side of the electrode assembly along the direction K, and the second end 24 of the negative electrode active material region 211 exceeds the fourth end 14 of the positive electrode active material region 111 along the direction K.

[0093] The extent to which both ends of the negative electrode active material region 211 extend along the winding axis K beyond the corresponding ends of the positive electrode active material region 111 may be the same or different, and the extent may range, for example, from 0.2 millimeters to 5 millimeters.

[0094] FIG. 10 is a schematic cross-sectional view taken along the line BB in FIG. 8. As shown in FIG. 8, the barrier layer 4 is attached onto the surface of the positive electrode active material region 111, that is, onto the surface of the positive electrode active material layer.

[0095] In order to not only block lithium ions but also save costs, the barrier layer 4 has a fifth end 42 and a sixth end 43 along a direction perpendicular to the folding direction (i.e., direction K), and the fifth end 42 of the barrier layer 4 exceeds the positive electrode active material layer of the positive electrode plate 1, and / or the sixth end 43 of the barrier layer 4 exceeds the positive electrode active material layer, i.e., the fifth end 42 of the barrier layer 4 exceeds the third end 13 of the positive electrode active material region 111 along the direction K, and / or the sixth end 43 of the barrier layer 4 exceeds the fourth end 14 of the positive electrode active material region 111 along the direction K, for example, the range of the excess dimension is 0.2 mm to 5 mm. In this way, it is possible to block the passage of many lithium ions and reduce the occurrence of lithium precipitation.

[0096] In another embodiment of the present application, neither the fifth end 42 nor the sixth end 43 of the barrier layer 4 exceeds the corresponding end of the negative electrode active material layer of the negative electrode plate 2, i.e., the first end 23 of the negative electrode active material region of the negative electrode plate 2 exceeds the fifth end 42 of the barrier layer 4, and / or the second end 24 of the negative electrode active material region of the negative electrode plate 2 exceeds the sixth end 43 of the barrier layer 4. In this way, lithium ions can be inserted into the portion of the negative electrode plate 2 that exceeds the barrier layer 4, and the energy density of the electrode assembly can be ensured.

[0097] The above examples merely roughly explain the positional relationship between the barrier layer and each of the positive and negative electrode plates, and the structural features of the barrier layer. In order to more clearly explain the positional relationship between the barrier layer and each of the positive and negative electrode plates, and the structure of the barrier layer, a detailed description will be given below using several electrode assemblies having a wound structure.

[0098] As shown in FIG. 11, this is a structural schematic diagram of a cross section perpendicular to the winding axis of a flat-shaped electrode assembly according to another embodiment of the present application. The electrode assembly includes a negative electrode plate 91, a positive electrode plate 92, a separator 93, a first barrier layer 94, a second barrier layer 95, and a third barrier layer 96. The separator 93 is located between the negative electrode plate 91 and the positive electrode plate 92. There are two separators 93, which are indicated by two wound dashed lines in the cross-sectional view of the electrode assembly in FIG. 11. The negative electrode plate 91, the positive electrode plate 92, and the separator 93 are stacked and then wound around the winding axis to form a flat-shaped wound structure.

[0099] Regarding technical features relating to the negative electrode plate 91, the positive electrode plate 92, and the separator 93 of this embodiment, the description of the embodiment corresponding to the above-mentioned Figs. 1-10 may be referred to, and detailed description thereof will be omitted here.

[0100] In this embodiment, the winding structure of the electrode assembly includes a flat region 9A and a first folding region 9B1 and a second folding region 9B2 located on either side of the flat region 9A, and the flat region 9A is defined by straight lines and the first folding region 9B1 and the second folding region 9B2, respectively.

[0101] The negative electrode plates 91 and the positive electrode plates 92 provided in the first folding region 9B1 and the second folding region 9B2 of the electrode assembly are stacked alternately in order, a separator 93 is provided between the adjacent negative electrode plates 91 and the positive electrode plates 92, the innermost electrode plates in the first folding region 9B1 and the second folding region 9B2 are both negative electrode plates 91, and a barrier layer is provided (e.g., attached) on the inner surface of at least the innermost positive electrode plate 92 in the first folding region 9B1 and the second folding region 9B2, for example, a barrier layer is provided (e.g., attached) on the inner surface of each layer of the positive electrode plate 92 in the first folding region 9B1 and the second folding region 9B2. In this embodiment, the inner surface of the positive electrode plate 92 is the surface facing the winding axis of the positive electrode plate 92 or the surface facing the inside of the winding structure.

[0102] For example, the first folding region 9B1 has multiple layers of plates, for example three layers of plates, the innermost layer (which may be called the first layer) and the outermost layer (which may be called the third layer) of the first folding region 9B1 are both negative electrode plates 91, the plate between the innermost layer plate and the outermost layer plate (which may be called the second layer plate) is a positive electrode plate 92, which is the innermost positive electrode plate in the first folding region 9B1, and a first barrier layer 94 is attached to the inner surface of the positive electrode plate 92 in the first folding region 9B1.

[0103] The second folding region 9B2 has multiple layers of plates, for example five layers of plates, and the negative electrode plates 91 and positive electrode plates 92 in the second folding region 9B2 are stacked alternately in sequence from the inside to the outside of the winding structure, with the negative electrode plate 91 being the innermost electrode plate in the second folding region 9B2, and a barrier layer being attached to the inner surface of each layer of the positive electrode plates 92 in the second folding region 9B2.

[0104] For example, along the direction from the inside to the outside of the winding structure, the second folding region 9B2 includes first, second, third, fourth and fifth layers of plates in order, the first, third and fifth layers of plates are negative plates 91, the second and fourth layers of plates are positive plates 92, and a barrier layer is attached to the inner surface of the positive plates 92 of each layer in the second folding region 9B2. For example, a second barrier layer 95 is attached to the inner surface of the second layer of plates (positive plates 92) in the second folding region 9B2. A third barrier layer 96 is attached to the inner surface of the fourth layer of plates (positive plates 92) in the second folding region 9B2.

[0105] In this embodiment, both ends along the folding direction (i.e., the winding direction) of the first barrier layer 94, the second barrier layer 95, and the third barrier layer 96 are each located at the boundary between the folding region and the flat region. For example, both ends along the winding direction of the first barrier layer 94 are each located at the boundary between the first folding region 9B1 and the flat region 9A, and both ends along the winding direction of the second barrier layer 95 and the third barrier layer 96 are each located at the boundary between the second folding region 9B2 and the flat region 9A.

[0106] In this embodiment, the functions, structures, distribution patterns, and other related contents of the first barrier layer 94, the second barrier layer 95, and the third barrier layer 96 can be referred to the related contents of the barrier layers described in the above embodiment of Figures 1-10, and detailed description thereof will be omitted here.

[0107] As shown in Figure 12, this is a schematic structural diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. The electrode assembly comprises a negative electrode plate 1001, a positive electrode plate 1002, a separator 1003, a first barrier layer 1004, a second barrier layer 1005 and a third barrier layer 1006, and the separator 1003 is located between the negative electrode plate 1001 and the positive electrode plate 1002. The negative electrode plate 1001, the positive electrode plate 1002 and the separator 1003 are stacked and then wound around the winding axis to form a flat-shaped winding structure.

[0108] Regarding technical features related to the negative electrode plate 1001, the positive electrode plate 1002, and the separator 1003 of this embodiment, the description of the embodiment corresponding to FIG. 1-10 above may be referred to, and detailed description will be omitted here.

[0109] In this embodiment, the wound structure of the electrode assembly includes a flat region 10A, and a first folded region 10B1 and a second folded region 10B2 located on either side of the flat region 10A.

[0110] The electrode assembly of this embodiment is substantially similar to the electrode assembly described in the embodiment corresponding to FIG. 11, except for the following points.

[0111] A barrier layer is provided (e.g., attached) to the outer surface of at least the innermost positive electrode plate 1002 in the first folding region 10B1 and the second folding region 10B2, for example, a barrier layer is provided (e.g., attached) to the outer surface of the positive electrode plate 1002 in each layer of the first folding region 10B1 and the second folding region 10B2. In this embodiment, the outer surface of the positive electrode plate 1002 is the surface opposite the winding axis of the positive electrode plate 1002 or the surface opposite the interior of the winding structure.

[0112] For example, a first barrier layer 1004 is attached to the outer surface of the positive electrode plate 1002 in the first fold region 10B1.

[0113] For example, a second barrier layer 1005 is attached to the outer surface of the second layer plate (positive electrode plate 1002) in the second folding region 10B2. A third barrier layer 1006 is attached to the outer surface of the fourth layer plate (positive electrode plate 1002) in the second folding region 10B2.

[0114] In this embodiment, both ends of the first barrier layer 1004 along the winding direction are located at the boundary between the first folding region 10B1 and the flat region 10A, and both ends of the second barrier layer 1005 and the third barrier layer 1006 along the winding direction are located at the boundary between the second folding region 10B2 and the flat region 10A.

[0115] In this embodiment, the functions, structures, distribution methods, and other related contents of the first barrier layer 1004, the second barrier layer 1005, and the third barrier layer 1006 can be referred to the related contents of the barrier layers described in the above embodiment of Figures 1-10, and detailed description thereof will be omitted here.

[0116] As shown in Figure 13, this is a schematic structural diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application, in which the electrode assembly comprises a negative electrode plate 1101, a positive electrode plate 1102, a separator 1103, a first barrier layer 1104, a second barrier layer 1105, a third barrier layer 1106, a fourth barrier layer 1107 and a fifth barrier layer 1108, and the separator 1103 is located between the negative electrode plate 1101 and the positive electrode plate 1102. The negative electrode plate 1101, the positive electrode plate 1102 and the separator 1103 are stacked and then wound around the winding axis to form a flat-shaped winding structure.

[0117] Regarding technical features related to the negative electrode plate 1101, the positive electrode plate 1102, and the separator 1103 of this embodiment, reference may be made to the description of the embodiment corresponding to FIG. 1-10 above, and detailed description thereof will be omitted here.

[0118] In this embodiment, the wound structure of the electrode assembly includes a flat region 11A, and a first folded region 11B1 and a second folded region 11B2 located on either side of the flat region 11A.

[0119] The electrode assembly of this embodiment is substantially similar to the electrode assembly described in the embodiment corresponding to FIG. 11, except for the following points.

[0120] A barrier layer is provided (e.g., attached) to the inner surface of at least the innermost negative electrode plate 1101 in the first folding region 11B1 and the second folding region 11B2, for example, a barrier layer is provided on the inner surface of the negative electrode plate 1101 of each layer in the first folding region 11B1 and the second folding region 11B2. In this embodiment, the inner surface of the negative electrode plate 1101 is the surface facing the winding axis of the negative electrode plate 1101 or the surface facing the inside of the winding structure.

[0121] For example, the first barrier layer 1104 is attached to the inner surface of the innermost electrode plate (negative electrode plate 1101) in the first folded region 11B1, and the second barrier layer 1105 is attached to the inner surface of the outermost electrode plate (negative electrode plate 1101).

[0122] For example, the third barrier layer 1106 is attached to the inner surface of the first layer of plates (negative plate 1101) in the second folding region 11B2. The fourth barrier layer 1107 is attached to the inner surface of the third layer of plates (negative plate 1101) in the second folding region 11B2. The fifth barrier layer 1108 is attached to the inner surface of the fifth layer of plates (negative plate 1101) in the second folding region 11B2.

[0123] In this embodiment, both ends of the first barrier layer 1104 and the second barrier layer 1105 along the winding direction are each located at the boundary between the first folding region 11B1 and the flat region 11A, and both ends of the third barrier layer 1106, the fourth barrier layer 1107 and the fifth barrier layer 1108 along the winding direction are each located at the boundary between the second folding region 11B2 and the flat region 11A.

[0124] In this embodiment, for the relevant contents such as the functions, structures, and distribution methods of the first barrier layer 1104, the second barrier layer 1105, the third barrier layer 1106, the fourth barrier layer 1107, and the fifth barrier layer 1108, it is sufficient to refer to the relevant contents of the barrier layers described in the above embodiment of Figures 1-10, and detailed explanations are omitted here.

[0125] As shown in Figure 14, this is a structural schematic diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. The electrode assembly comprises a negative electrode plate 1201, a positive electrode plate 1202, a separator 1203, a first barrier layer 1204, a second barrier layer 1205, a third barrier layer 1206, a fourth barrier layer 1207 and a fifth barrier layer 1208, and the separator 1203 is located between the negative electrode plate 1201 and the positive electrode plate 1202. The negative electrode plate 1201, the positive electrode plate 1202 and the separator 1203 are stacked and then wound around the winding axis to form a flat-shaped winding structure.

[0126] Regarding technical features related to the negative electrode plate 1201, the positive electrode plate 1202, and the separator 1203 of this embodiment, the description of the embodiment corresponding to FIG. 1-10 may be referred to, and detailed description will be omitted here.

[0127] In this embodiment, the wound structure of the electrode assembly includes a flat region 12A, and a first folded region 12B1 and a second folded region 12B2 located on either side of the flat region 12A.

[0128] The electrode assembly of this embodiment is substantially similar to the electrode assembly described in the embodiment corresponding to FIG. 11, except for the following points.

[0129] A barrier layer is provided (e.g., attached) to the outer surface of at least the innermost negative electrode plate 1201 in the first folding region 12B1 and the second folding region 12B2, for example, a barrier layer is provided on the outer surface of the negative electrode plate 1201 in each layer of the first folding region 12B1 and the second folding region 12B2. In this embodiment, the outer surface of the negative electrode plate 1201 is the surface opposite the winding axis of the negative electrode plate 1201 or the surface opposite the inside of the winding structure.

[0130] For example, the first barrier layer 1204 is attached to the outer surface of the innermost plate (negative electrode plate 1201) in the first folding region 12B1, and the second barrier layer 1205 is attached to the outer surface of the outermost plate (negative electrode plate 1201).

[0131] For example, a third barrier layer 1206 is attached to the outer surface of the first layer of plates (negative plate 1201) in the second folding region 12B2. A fourth barrier layer 1207 is attached to the outer surface of the third layer of plates (negative plate 1201) in the second folding region 12B2. A fifth barrier layer 1208 is attached to the outer surface of the fifth layer of plates (negative plate 1201) in the second folding region 12B2.

[0132] In this embodiment, both ends of the first barrier layer 1204 and the second barrier layer 1205 along the winding direction are respectively located at the boundary between the first folding region 12B1 and the flat region 12A, and both ends of the third barrier layer 1206, the fourth barrier layer 1207 and the fifth barrier layer 1208 along the winding direction are respectively located at the boundary between the second folding region 12B2 and the flat region 12A.

[0133] In this embodiment, for the relevant contents such as the functions, structures, and distribution methods of the first barrier layer 1204, the second barrier layer 1205, the third barrier layer 1206, the fourth barrier layer 1207, and the fifth barrier layer 1208, it is sufficient to refer to the relevant contents of the barrier layers described in the above embodiment of Figures 1-10, and detailed explanations are omitted here.

[0134] As shown in Figure 15, this is a structural schematic diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. The electrode assembly includes a negative electrode plate 1301, a positive electrode plate 1302, a separator 1303, and a plurality of barrier layers 1304, and the separator 1303 is located between the negative electrode plate 1301 and the positive electrode plate 1302. The negative electrode plate 1301, the positive electrode plate 1302, and the separator 1303 are stacked and then wound around the winding axis to form a flat-shaped winding structure.

[0135] Regarding technical features related to the negative electrode plate 1301, the positive electrode plate 1302, and the separator 1303 of this embodiment, the description of the embodiment corresponding to FIG. 1-10 may be referred to, and detailed description will be omitted here.

[0136] In this embodiment, the wound structure of the electrode assembly includes a flat region 13A, and a first folded region 13B1 and a second folded region 13B2 located on either side of the flat region 13A.

[0137] The electrode assembly of this embodiment is substantially similar to the electrode assembly described in the embodiment corresponding to FIG. 11, except for the following points.

[0138] A barrier layer 1304 is attached to the inner surface of at least the innermost separator 1303 in the first folding region 13B1 and the second folding region 13B2, for example, the barrier layer 1304 is attached to the inner surface of the separator 1303 in each of the first folding region 13B1 and the second folding region 13B2. In this embodiment, the inner surface of the separator 1303 is the surface facing the winding axis of the separator 1303 or the surface facing the inside of the winding structure.

[0139] In this embodiment, both ends along the winding direction of each barrier layer 1304 in the first folding region 13B1 are located at the boundary between the first folding region 13B1 and the flat region 13A, and both ends along the winding direction of each barrier layer 1304 in the second folding region 13B2 are located at the boundary between the second folding region 12B2 and the flat region 12A.

[0140] In this embodiment, the function, structure, distribution method, and other related content of each barrier layer 1304 may be referred to the related content of the barrier layer described in the embodiment of FIGS. 1-10, and detailed description thereof will be omitted here.

[0141] As shown in Figure 16, this is a schematic structural diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. The electrode assembly comprises a negative electrode plate 1401, a positive electrode plate 1402, a separator 1403, and a plurality of barrier layers 1404, and the separator 1403 is located between the negative electrode plate 1401 and the positive electrode plate 1402. The negative electrode plate 1401, the positive electrode plate 1402, and the separator 1403 are stacked and then wound around the winding axis to form a flat-shaped winding structure.

[0142] Regarding technical features related to the negative electrode plate 1401, the positive electrode plate 1402, and the separator 1403 of this embodiment, the description of the embodiment corresponding to FIG. 1-10 may be referred to, and detailed description will be omitted here.

[0143] In this embodiment, the wound structure of the electrode assembly includes a flat region 14A, and a first folded region 14B1 and a second folded region 14B2 located on either side of the flat region 14A.

[0144] The electrode assembly of this embodiment is substantially similar to the electrode assembly described in the embodiment corresponding to FIG. 11, except for the following points.

[0145] A barrier layer 1404 is attached to the outer surface of at least the innermost separator 1403 in the first folding region 14B1 and the second folding region 14B2, for example, the barrier layer 1404 is attached to the outer surface of the separator 1403 in each of the first folding region 14B1 and the second folding region 14B2. In this embodiment, the outer surface of the separator 1403 is the surface opposite the winding axis of the separator 1403 or the surface opposite the interior of the winding structure.

[0146] In this embodiment, both ends along the winding direction of each barrier layer 1404 in the first folding region 14B1 are located at the boundary between the first folding region 14B1 and the flat region 14A, and both ends along the winding direction of each barrier layer 1404 in the second folding region 14B2 are located at the boundary between the second folding region 12B2 and the flat region 12A.

[0147] In this embodiment, the function, structure, distribution manner, and other related content of each barrier layer 1404 may be referred to the related content of the barrier layer described in the embodiment of FIGS. 1-10, and detailed description thereof will be omitted here.

[0148] As shown in Figure 17, this is a schematic structural diagram of a cross section perpendicular to the winding axis of another flat-shaped electrode assembly according to another embodiment of the present application. The electrode assembly includes a negative electrode plate 1501, a positive electrode plate 1502, a separator 1503, and a plurality of barrier layers 1504, and the separator 1503 is located between the negative electrode plate 1501 and the positive electrode plate 1502. The negative electrode plate 1501, the positive electrode plate 1502, and the separator 1503 are stacked and then wound around the winding axis to form a flat-shaped winding structure.

[0149] Regarding technical features related to the negative electrode plate 1501, the positive electrode plate 1502, and the separator 1503 of this embodiment, the description of the embodiment corresponding to FIG. 1-10 may be referred to, and detailed description will be omitted here.

[0150] In this embodiment, the wound structure of the electrode assembly includes a flat region 15A, and a first folded region 15B1 and a second folded region 15B2 located on either side of the flat region 15A.

[0151] The negative electrode plates 1501 and positive electrode plates 1502 provided in the first folding region 15B1 and the second folding region 15B2 of the electrode assembly are stacked alternately in order, a separator 1503 is provided between any adjacent negative electrode plates 1501 and positive electrode plates 1502 in the first folding region 15B1 and the second folding region 15B2, the innermost electrode plates in the first folding region 15B1 and the second folding region 15B2 are both negative electrode plates 1501, and a barrier layer 1504 is provided on both the inner and outer surfaces of at least the innermost positive electrode plate 1502 in the first folding region 15B1 and the second folding region 15B2, for example, a barrier layer 1504 is provided on both the inner and outer surfaces of the positive electrode plate 1502 in each layer in the first folding region 15B1 and the second folding region 15B2. In this embodiment, the inner surface of the positive electrode plate 1502 is the surface facing the winding axis of the positive electrode plate 1502 or the surface facing the inside of the winding structure, and the outer surface of the positive electrode plate 1502 is the surface opposite the winding axis of the positive electrode plate 1502 or the surface opposite the inside of the winding structure.

[0152] For example, the first folding region 15B1 has multiple layers of plates, for example, three layers of plates, the innermost layer (which may be referred to as the first layer) and the outermost layer (which may be referred to as the third layer) of the first folding region 15B1 are both negative electrode plates 1501, the plate between the innermost layer plate and the outermost layer plate of the first folding region 15B1 (which may be referred to as the second layer plate) is a positive electrode plate 1502, and a barrier layer 1504 is provided (e.g., attached) to both the inner and outer surfaces of the positive electrode plate 1502 in the first folding region 15B1.

[0153] The second folding region 15B2 has multiple layers of plates, for example five layers of plates, and the negative electrode plates 1501 and positive electrode plates 1502 in the second folding region 15B2 are stacked alternately in sequence along the direction from the inside to the outside of the winding structure, with the electrode plate in the innermost layer of the second folding region 15B2 being the negative electrode plate 1501, and a barrier layer 1504 being provided (e.g., attached) to both the inner and outer surfaces of the positive electrode plates 1502 in each layer of the second folding region 15B2.

[0154] For example, along the inside-to-outside direction of the winding structure, the second folded region 15B2 has first, second, third, fourth and fifth layers of plates in order, the first, third and fifth layers of plates being negative electrode plates 1501, the second and fourth layers of plates being positive electrode plates 1502, and a barrier layer 1504 is provided on both the inner and outer surfaces of the second and fourth layers of plates in the second folded region 15B2.

[0155] In this embodiment, both ends along the folding direction (i.e., the winding direction) of each barrier layer 1504 are located at the boundary between the folding region and the flat region. For example, both ends along the winding direction of each barrier layer 1504 in the first folding region 15B1 are located at the boundary between the first folding region 15B1 and the flat region 15A, and both ends along the winding direction of each barrier layer 1504 in the second folding region 15B2 are located at the boundary between the second folding region 15B2 and the flat region 15A.

[0156] In this embodiment, the function, structure, distribution method, and other related content of each barrier layer 1504 can be referred to the related content of the barrier layer described in the embodiment of FIGS. 1-10, and detailed description will be omitted here.

[0157] As shown in Figure 18, this is a schematic structural diagram of a cross section perpendicular to the winding axis of a flat-shaped electrode assembly according to another embodiment of the present application, in which the electrode assembly comprises a negative electrode plate 1601, a positive electrode plate 1602, a separator 1603, a first barrier layer 1604, a second barrier layer 1605 and a third barrier layer 1606, and the separator 1603 is located between the negative electrode plate 1601 and the positive electrode plate 1602. The negative electrode plate 1601, the positive electrode plate 1602 and the separator 1603 are stacked and then wound around the winding axis to form a flat-shaped winding structure.

[0158] Regarding technical features related to the negative electrode plate 1601, the positive electrode plate 1602, and the separator 1603 of this embodiment, the description of the embodiment corresponding to FIG. 1-10 may be referred to, and detailed description will be omitted here.

[0159] In this embodiment, the winding structure of the electrode assembly includes a first flat region 16A1, a second flat region 16A2, a first folding region 16B1 and a second folding region 16B2, the first flat region 16A1 and the second flat region 16A2 are arranged opposite each other, the first folding region 16B1 and the second folding region 16B2 are arranged opposite each other, both ends of the first folding region 16B1 are respectively connected to the same side ends of the first flat region 16A1 and the second flat region 16A2, and both ends of the second folding region 16B2 are respectively connected to another same side end of the first flat region 16A1 and the second flat region 16A2.

[0160] The negative electrode plates 1601 and positive electrode plates 1602 provided in the first folding region 16B1 and the second folding region 16B2 of the electrode assembly are stacked alternately in order, with separators 1603 between adjacent negative electrode plates 1601 and positive electrode plates 1602, the innermost plates in the first folding region 16B1 and the second folding region 16B2 are both negative electrode plates 1601, and a barrier layer is provided (e.g., attached) to the inner surface of at least the innermost positive electrode plate 1602 in the first folding region 16B1 and the second folding region 16B2, for example, a barrier layer is provided (e.g., attached) to the inner surface of each layer of positive electrode plates 1602 in the first folding region 16B1 and the second folding region 16B2. In this embodiment, the inner surface of the positive electrode plate 1602 is the surface that faces the winding axis of the positive electrode plate 1602 or the surface that faces the inside of the winding structure.

[0161] For example, the first folding region 16B1 has multiple layers of plates, for example three layers of plates, in which the innermost layer (which may be called the first layer) and the outermost layer (which may be called the third layer) of the first folding region 16B1 are both negative electrode plates 1601, the plate between the innermost layer and the outermost layer (which may be called the second layer) is a positive electrode plate 1602, and a first barrier layer 1604 is attached to the inner surface of the positive electrode plate 1602 in the first folding region 16B1.

[0162] For example, the second folding region 16B2 has multiple layers of plates, for example five layers of plates, and along the direction from the inside to the outside of the winding structure, the negative electrode plates 1601 and the positive electrode plates 1602 in the second folding region 16B2 are stacked alternately in sequence, the electrode plate in the innermost layer of the second folding region 16B2 is the negative electrode plate 1601, and a barrier layer is attached to the inner surface of each layer of the positive electrode plates 1602 in the second folding region 16B2.

[0163] For example, along the direction from the inside to the outside of the winding structure, the second folding region 16B2 includes first, second, third, fourth and fifth layers of plates in order, the first, third and fifth layers of plates are negative plates 1601, the second and fourth layers of plates are positive plates 1602, and the second barrier layer 1605 is attached on the inner surface of the positive plate 1602 of the innermost adjacent negative plate 1601 and positive plate 1602 of the second folding region 16B2, i.e., the second barrier layer 1605 is attached to the inner surface of the second layer plate (positive plate 1602) of the second folding region 16B2. The third barrier layer 1606 is attached to the inner surface of the fourth layer plate (positive plate 1602) of the second folding region 16B2.

[0164] In this embodiment, the first barrier layer 1604 has a first end and a second end along the folding direction (i.e., the rolling direction), the first end of the first barrier layer 1604 is located in the first folding region 16B1, and the second end of the first barrier layer 1604 is located in the first flat region 16A1. The second barrier layer 1605 has a first end and a second end along the folding direction (i.e., the rolling direction), the first end of the second barrier layer 1605 is located in the second folding region 16B2, and the second end of the second barrier layer 1605 is located in the second flat region 16A2. The third barrier layer 1606 has a first end and a second end along the folding direction (i.e., the rolling direction), the first end of the third barrier layer 1606 is located in the second folding region 16B2, and the second end of the third barrier layer 1606 is located in the second flat region 16A2. As in other embodiments of the present application, a first end of the third barrier layer 1606 may be located in the second fold region 16B2 and a second end of the third barrier layer 1606 may be located in the first flat region 16A1.

[0165] In this embodiment, the functions, structures, distribution methods, and other related contents of the first barrier layer 1604, the second barrier layer 1605, and the third barrier layer 1606 can be referred to the related contents of the barrier layers described in the above embodiment of Figures 1-10, and detailed explanations are omitted here.

[0166] As shown in Figure 19, this is a schematic structural diagram of a cross section perpendicular to the winding axis of a flat-shaped electrode assembly according to another embodiment of the present application, in which the electrode assembly comprises a negative electrode plate 1701, a positive electrode plate 1702, a separator 1703, a first barrier layer 1704, a second barrier layer 1705, and a third barrier layer 1706, and separator 1703 is located between negative electrode plate 1701 and positive electrode plate 1702. Negative electrode plate 1701, positive electrode plate 1702, and separator 1703 are stacked and then wound around the winding axis to form a flat-shaped winding structure.

[0167] Regarding technical features related to the negative electrode plate 1701, the positive electrode plate 1702, and the separator 1703 of this embodiment, the description of the embodiment corresponding to FIG. 1-10 may be referred to, and detailed description will be omitted here.

[0168] In this embodiment, the winding structure of the electrode assembly includes a first flat region 17A1, a second flat region 17A2, a first folding region 17B1 and a second folding region 17B2, the first flat region 17A1 and the second flat region 17A2 are arranged opposite each other, the first folding region 17B1 and the second folding region 17B2 are arranged opposite each other, both ends of the first folding region 17B1 are respectively connected to the same side ends of the first flat region 17A1 and the second flat region 17A2, and both ends of the second folding region 17B2 are respectively connected to another same side end of the first flat region 17A1 and the second flat region 17A2.

[0169] The negative electrode plates 1701 and positive electrode plates 1702 provided in the first folding region 17B1 and the second folding region 17B2 of the electrode assembly are stacked alternately in order, with separators 1703 between adjacent negative electrode plates 1701 and positive electrode plates 1702, the innermost plates in the first folding region 17B1 and the second folding region 17B2 are both negative electrode plates 1701, and a barrier layer is provided (e.g., attached) to the inner surface of at least the innermost positive electrode plate 1702 in the first folding region 17B1 and the second folding region 17B2, for example, a barrier layer is provided (e.g., attached) to the inner surface of each layer of positive electrode plates 1702 in the first folding region 17B1 and the second folding region 17B2. In this embodiment, the inner surface of the positive electrode plate 1702 is the surface that faces the winding axis of the positive electrode plate 1702 or the surface that faces the inside of the winding structure.

[0170] For example, the first folding region 17B1 has multiple layers of plates, for example three layers of plates, the innermost layer (which may be referred to as the first layer) and the outermost layer (which may be referred to as the third layer) of the first folding region 17B1 are both negative electrode plates 1701, the plate between the innermost layer plate and the outermost layer plate (which may be referred to as the second layer plate) is a positive electrode plate 1702, and a first barrier layer 1704 is attached to the inner surface of the positive electrode plate 1702 in the first folding region 17B1.

[0171] The second folding region 17B2 has multiple layers of plates, for example five layers of plates, and the negative electrode plates 1701 and positive electrode plates 1702 in the second folding region 17B2 are stacked alternately in sequence from the inside to the outside of the winding structure, with the negative electrode plate 1701 being the innermost electrode plate in the second folding region 17B2, and a barrier layer being attached to the inner side surface of each layer of positive electrode plates 1702 in the second folding region 17B2.

[0172] For example, along the direction from the inside to the outside of the winding structure, the second folding region 17B2 includes first, second, third, fourth and fifth layers of plates in order, the first, third and fifth layers of plates are negative plates 1701, the second and fourth layers of plates are positive plates 1702, and the second barrier layer 1705 is attached to the inner surface of the positive plate 1702 among the innermost adjacent negative plate 1701 and positive plate 1702 in the second folding region 17B2, i.e., the second barrier layer 1705 is attached to the inner surface of the second layer of plates (positive plate 1702) in the second folding region 17B2. The third barrier layer 1706 is attached to the inner surface of the fourth layer of plates (positive plate 1702) in the second folding region 17B2.

[0173] In this embodiment, the first barrier layer 1704 has a first end and a second end along the folding direction (i.e., the rolling direction), and both the first end and the second end of the first barrier layer 1704 are located in the first folding region 17B1. The second barrier layer 1705 has a first end and a second end along the folding direction (i.e., the rolling direction), and the first end of the second barrier layer 1705 is located at the boundary between the second folding region 17B2 and the first flat region 17A1, and the second end of the second barrier layer 1705 is located at the boundary between the second folding region 17B2 and the second flat region 17A2. The third barrier layer 1706 has a first end and a second end along the folding direction (i.e., the rolling direction), and both the first end and the second end of the third barrier layer 1706 are located in the second folding region 17B2.

[0174] In this embodiment, in the second folding region 17B2, the curvature of the electrode plates of each layer becomes smaller in the direction perpendicular to the winding axis from the inside to the outside of the electrode assembly, i.e., the degree of folding gradually decreases. In this case, the circumferential angle that each barrier layer covers in the second folding region 17B2 along the winding direction may become smaller in the direction perpendicular to the winding axis from the inside to the outside of the electrode assembly. For example, the circumferential angle that the third barrier layer 1706 covers in the winding direction in the second folding region 17B2 is less than the circumferential angle that the second barrier layer 1705 covers in the second folding region 17B2. For example, the circumferential angle that the third barrier layer 1706 covers in the winding direction in the second folding region 17B2 is 90°, and the circumferential angle that the second barrier layer 1705 covers in the winding direction in the second folding region 17B2 is 180°.

[0175] In this embodiment, the functions, structures, distribution methods, and other related contents of the first barrier layer 1704, the second barrier layer 1705, and the third barrier layer 1706 can be referred to the related contents of the barrier layers described in the above embodiment of Figures 1-10, and detailed explanations are omitted here.

[0176] 20 is a structural schematic diagram of a battery cell according to another embodiment of the present application. The battery cell includes a casing 181 and one or more electrode assemblies 182 housed in the casing 181, the casing 181 includes a housing 1811 and a cover plate 1812, the housing 1811 has a housing chamber, and the housing 1811 has an opening, that is, the flat surface does not have a housing wall, so that the inside and outside of the housing 1811 communicate with each other, so that the electrode assembly 182 can be housed in the housing chamber of the housing 1811, the cover plate 1812 and the housing 1811 are connected at the opening of the housing 1811 to form a hollow chamber, and after the electrode assembly 182 is housed in the casing 181, the casing 181 is filled with an electrolyte and sealed.

[0177] The housing 1811 is determined according to the combined shape of one or more electrode assemblies 182, and for example, the housing 1811 may be a hollow rectangular parallelepiped, a hollow cube, or a hollow cylinder. For example, when the housing 1811 is a hollow rectangular parallelepiped or a hollow cube, one plane of the housing 1811 is an open surface, i.e., the plane communicates the inside and outside of the housing 1811 due to the absence of a housing wall, and when the housing 1811 is a hollow cylinder, one circular side surface of the housing 1811 is an open surface, i.e., the circular side surface communicates the inside and outside of the housing 1811 due to the absence of a housing wall.

[0178] In another embodiment of the present application, the housing 1811 may be made of a conductive metallic material or plastic, and optionally, the housing 1811 is made of aluminum or an aluminum alloy.

[0179] Regarding the structure of the electrode assembly 182, reference may be made to the relevant content of the electrode assembly described in the embodiment of FIGS. 1-19 above, and detailed description thereof will be omitted here.

[0180] As shown in FIG. 21, this is a structural schematic diagram of a battery module according to another embodiment of the present application. The battery module 19 includes a plurality of battery cells 191 connected to each other, and the plurality of battery cells 191 may be connected in series, in parallel, or in series-parallel, where series-parallel connection means that the connection includes both series and parallel connections. With regard to the structure of the battery cell 191, it is sufficient to refer to the battery cell described in the embodiment corresponding to FIG. 20, and a detailed description will be omitted here.

[0181] As shown in FIG. 22, this is a structural schematic diagram of a battery according to another embodiment of the present application, in which the battery comprises a plurality of battery modules 19 and a housing, the housing comprises a lower housing 20 and an upper housing 30, the plurality of battery modules 19 may be connected in series or in parallel or in series-parallel, the lower housing 20 has an accommodation chamber, and the lower housing 20 has an opening, so that the plurality of battery modules 19 after connection can be accommodated in the accommodation chamber of the lower housing 20, the upper housing 30 and the lower housing 20 are connected at the opening of the lower housing 20 to form a hollow chamber, and the upper housing 30 and the lower housing 20 are sealed after being connected.

[0182] In another embodiment of the present application, the battery may solely power a power consuming device, and the battery may be referred to as a battery pack, for example, as used to power an automobile.

[0183] In another embodiment of the present application, a plurality of batteries may be interconnected to form a battery pack for powering a power consuming device according to the power consumption needs of the power consuming device, and the battery pack may also be packaged within a housing.

[0184] For simplicity, the following embodiments are described taking the example in which the power consuming device includes a battery.

[0185] An embodiment of the present application further provides a power consuming device, for example, the power consuming device may be a vehicle such as a new energy vehicle, the power consuming device may include a battery as described in the above embodiment, and the battery used in the power consuming device may be such as the battery as described in the embodiment corresponding to Figure 22, and detailed description thereof will be omitted here.

[0186] For example, as shown in FIG. 23, it is a structural schematic diagram of a power consumption device according to another embodiment of the present application, the power consumption device may be a car, the car may be a fuel car, a gas car or a new energy car, the new energy car may be a pure electric car, a hybrid car or an extended range electric car, etc. The car includes a battery 2101, a controller 2102 and a motor 2103. The battery 2101 is used to power the controller 2102 and the motor 2103, and functions as an operating power source and a driving power source of the car, for example, the battery 2101 is used for starting the car, navigation and operating power demand during driving. For example, the battery 2101 supplies power to the controller 2102, the controller 2102 controls the battery 2101 to supply power to the motor 2103, and the motor 2103 receives power from the battery 2101 and uses it as a driving power source of the car, replacing or partially replacing fuel or natural gas to provide driving power to the car.

[0187] As shown in FIG. 24, which is a schematic flowchart of a method for manufacturing an electrode assembly according to another embodiment of the present application, the method for manufacturing an electrode assembly includes the following steps 221 to 222.

[0188] Step 221 provides a positive electrode plate, a negative electrode plate and a barrier layer.

[0189] In step 222, the positive and negative plates are wound or stacked to form a folding region.

[0190] The folding region has a barrier layer, and at least a portion of the barrier layer is located between adjacent positive and negative electrode plates and is used to prevent at least a portion of the ions desorbed from the positive electrode plate from being inserted into the folding region of the negative electrode plate.

[0191] In another embodiment of the present application, a separator is further provided to separate adjacent positive and negative plates, and the separator, positive and negative plates are wound or stacked together.

[0192] In another embodiment of the present application, a barrier layer is provided on one or two surfaces of the positive or negative plates before the separator, positive and negative plates are wound or stacked together, e.g., the barrier layer is applied or coated on one or two surfaces of the positive or negative plates.

[0193] Regarding the related structure of the electrode assembly manufactured by the manufacturing method of this embodiment, reference may be made to the related content of the electrode assembly described in the embodiment corresponding to Figures 1-19 above, and detailed description will be omitted here.

[0194] As shown in FIG. 25, this is a structural schematic diagram of an electrode assembly manufacturing equipment according to another embodiment of the present application, and the electrode assembly manufacturing equipment includes a first providing device 231, a second providing device 232, a third providing device 233 and an assembling device 234.

[0195] The first providing device 231 is used to provide a positive electrode plate.

[0196] The second providing device 232 is used to provide a negative electrode plate.

[0197] The third providing device 233 is used to provide a barrier layer.

[0198] The assembly device 234 is used to wind or stack the positive and negative plates to form the folding regions.

[0199] The folding region has a barrier layer, and at least a portion of the barrier layer is located between adjacent positive and negative electrode plates and is used to prevent at least a portion of the ions desorbed from the positive electrode plate from being inserted into the folding region of the negative electrode plate.

[0200] In another embodiment of the present application, the electrode assembly manufacturing equipment further includes a fourth providing device 235 for providing a separator for separating adjacent positive and negative electrode plates, and the assembling device 234 is used to wind or stack the positive and negative electrode plates and the separator to form a folding region.

[0201] In another embodiment of the present application, there are two third providing devices 233, and the two third providing devices 233 are respectively used to provide a barrier layer and attach or coat the barrier layer on two surfaces of the positive electrode plate or the negative electrode plate.

[0202] Regarding the related structure of the electrode assembly manufactured by the manufacturing equipment of this embodiment, reference may be made to the related content of the electrode assembly described in the embodiment corresponding to Figures 1-19 above, and detailed description will be omitted here.

[0203] As described above, by providing a barrier layer between adjacent positive and negative plates in an electrode assembly of a battery cell, at least a portion of the ions desorbed from the positive active material layer of the positive plate in the bent region during charging are blocked by the barrier layer, and the ions blocked by the barrier layer cannot be inserted into the negative active material layer in the bent region of the negative plate adjacent to the positive plate. If the negative active material falls off of the negative plate, the occurrence of lithium precipitation is reduced, the safety risk of the battery cell is improved, and the life of the battery cell is extended.

[0204] As will be understood by those skilled in the art, some embodiments herein may include certain features that are included in other embodiments but not other features, meaning that a combination of features from different embodiments falls within the scope of the present application and forms a different embodiment. For example, in the claims, any of the claimed embodiments may be used in any combination.

[0205] The above examples are used only to explain the technical solutions of the present application, but are not intended to limit the same. Although the present application has been described in detail with reference to the above examples, those skilled in the art can still understand that the technical solutions described in the above examples can still be modified or some of the technical features thereof can be equivalently replaced, and such modifications and replacements will not deviate from the spirit and scope of the technical solutions of the respective embodiments of the present application. [Explanation of symbols]

[0206] 1 Positive electrode plate 2 Negative electrode plate 3. Separator 4. Barrier Layer 9A, 10A, 11A, 12A, 13A, 14A, 15A flat area 9B1, 10B1, 11B1, 12B1, 13B1, 14B1, 15B1 First bending region 9B2, 10B2, 11B2, 12B2, 13B2, 14B2, 15B2 Second folding area 10 Current collector 12 Positive electrode tab 13 Third end 14 4th end 16A1, 17A1 1st flat area 16A2, 17A2 2nd flat area 16B1, 17B1 First bending area 16B2, 17B2 Second folding area 19 Battery Module 20 Lower case 21 Negative electrode body 22 Negative electrode tab part 23 First end 24 Second end 30 Upper case 41 Through hole 42 5th end 43 6th end 91 Negative electrode plate 92 Positive electrode plate 93 Separator 94 First Barrier Layer 95 Second Barrier Layer 96 3rd Barrier Layer 100 flat area 101 Negative electrode plate 102 Positive electrode plate 103 Separator 111 Cathode active material area 112 First insulating layer coating area 121 Second insulating layer coating area 181 Casing 182 Electrode assembly 191 Battery Cell 200 Bending region of electrode assembly 211 Negative electrode active material area 231 First providing device 232 Second providing device 233 Third providing device 234 Assembly Equipment 235 4th Providing Device 1001 Negative electrode plate 1002 Positive electrode plate 1003 Separator 1004 First barrier layer 1005 Second Barrier Layer 1006 3rd Barrier Layer 1101 Negative electrode plate 1102 Positive electrode plate 1103 Separator 1104 First Barrier Layer 1105 Second Barrier Layer 1106 3rd Barrier Layer 1107 4th Barrier Layer 1108 5th Barrier Layer 1201 Negative electrode plate 1202 Positive electrode plate 1203 Separator 1204 First Barrier Layer 1205 Second Barrier Layer 1206 3rd Barrier Layer 1207 4th Barrier Layer 1208 5th Barrier Layer 1301 Negative electrode plate 1302 Positive electrode plate 1303 Separator 1304 Barrier layer 1401 Negative electrode plate 1402 Positive electrode plate 1403 Separator 1404 Barrier Layer 1501 Negative electrode plate 1502 Positive electrode plate 1503 Separator 1504 Barrier layer 1601 Negative electrode plate 1602 Positive electrode plate 1603 Separator 1604 First Barrier Layer 1605 Second Barrier Layer 1606 3rd Barrier Layer 1701 Negative electrode plate 1702 Positive electrode plate 1703 Separator 1704 First Barrier Layer 1705 Second Barrier Layer 1706 3rd Barrier Layer 1811 Housing 1812 Cover Plate 2101 Battery 2102 Controller 2103 Motor

Claims

1. An electrode assembly comprising a positive electrode plate and a negative electrode plate, the positive electrode plate and the negative electrode plate being wound or stacked to form a folding region; The bent region has a barrier layer, at least a portion of the barrier layer is located between the adjacent positive electrode plate and the adjacent negative electrode plate, and is used to prevent at least a portion of ions desorbed from the positive electrode plate from being inserted into the negative electrode plate in the bent region; The barrier layer has two ends along a direction perpendicular to the folding direction, and one or both ends of the barrier layer extend beyond the positive electrode active material layer of the positive electrode plate.

2. 2. The electrode assembly of claim 1, further comprising a separator for separating adjacent positive and negative plates, wherein the barrier layer is attached to one or two surfaces of the positive plate and / or the barrier layer is attached to one or two surfaces of the negative plate and / or the barrier layer is attached to one or two surfaces of the separator.

3. 2. The electrode assembly according to claim 1, further comprising a separator for separating adjacent positive and negative plates, wherein the barrier layer is independently disposed between adjacent positive plates and the separator in the folded region, or the barrier layer is independently disposed between adjacent negative plates and the separator in the folded region.

4. The electrode assembly according to claim 2 or 3, wherein the porosity of the barrier layer is less than the porosity of the separator.

5. 4. The electrode assembly according to claim 1, comprising one positive electrode plate and one negative electrode plate, the one positive electrode plate and the one negative electrode plate being compressed and then wound to form a wound structure, and the barrier layer being present between at least an innermost adjacent positive electrode plate and negative electrode plate in the folding region.

6. 6. The electrode assembly of claim 5, wherein the innermost plate in the folded region is a negative plate.

7. The electrode assembly of any one of claims 1 to 3, wherein the barrier layer is discontinuous, and the discontinuous barrier layers are distributed at intervals along the folding direction, or the discontinuous barrier layers are distributed at intervals along a direction perpendicular to the folding direction.

8. The electrode assembly of any one of claims 1 to 3, wherein the barrier layer has a thickness of 2-200 microns, or 5-100 microns.

9. The electrode assembly of claim 1 , wherein the barrier layer has at least one through hole.

10. The electrode assembly of claim 9 , wherein the porosity of the barrier layer is 10%-70%, or 20%-60%.

11. the thickness of said barrier layer is A microns and the porosity of said barrier layer is B, where A and B are 10. The electrode assembly according to claim 9, which satisfies the relationship: 3.5 microns≦A / B≦2000 microns, or 7 microns≦A / B≦1000 microns.

12. 4. The electrode assembly according to claim 1, wherein both ends perpendicular to a folding direction of the negative electrode active material layer of the negative electrode plate extend beyond the corresponding ends of the positive electrode active material layer of the positive electrode plate.

13. The electrode assembly according to claim 1 , wherein the barrier layer has both ends along a direction perpendicular to a folding direction, and the negative electrode active material layer of the negative electrode plate extends beyond one or both ends of the barrier layer.

14. The electrode assembly according to claim 1 , wherein the barrier layer and the negative electrode plate are provided at portions with the largest curvatures facing each other.

15. The electrode assembly of any one of claims 1 to 3, wherein the barrier layer comprises at least one of an inorganic oxide, a binder, and a tape.

16. The electrode assembly according to claim 1 , wherein both ends of the barrier layer extending along the folding direction are located in the folding region.

17. the electrode assembly has a flat region connected to the bent region; An electrode assembly as described in any one of claims 1 to 3, wherein one end extending along the folding direction of the barrier layer is located in the flat region and the other end is located in the folding region, or both ends extending along the folding direction of the barrier layer are located in the flat region.

18. A battery cell comprising a housing, a cover plate, and at least one electrode assembly according to any one of claims 1 to 17, the housing has an accommodation chamber and an opening, the electrode assembly is accommodated in the accommodation chamber, The cover plate is used to seal the opening of the housing.

19. 20. A battery comprising: a housing; and at least one battery cell according to claim 18, said battery cell contained within said housing.

20. 20. A power consuming device configured to receive power from a battery according to claim 19.

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