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

Abstract

The embodiment of the invention discloses an electrode assembly, a battery monomer, a battery and a method and a device for manufacturing the electrode assembly, the electrode assembly comprises a positive pole piece and a negative pole piece, the positive pole piece and the negative pole piece are wound or laminated to form a bending area; the bending area is provided with a barrier layer, and at least one part of the barrier layer is located between the adjacent positive pole piece and negative pole piece and used for preventing at least one part of ions separated from the positive pole piece from being embedded into the negative pole piece of the bending area. According to the technical scheme, the barrier layer is arranged between the positive pole piece and the negative pole piece which are adjacent to each other in the bending area, so that at least one part of ions separated from the positive pole active material layer can be prevented from being embedded into the negative pole active material layer of the negative pole piece adjacent to the positive pole piece in the bending area, the occurrence of lithium precipitation is reduced, and the safety performance of the battery monomer is improved; the service life of the battery monomer is prolonged.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to an electrode assembly, a battery cell, a battery, and a method and device for manufacturing the electrode assembly. Background Art

[0002] Rechargeable batteries, also known as secondary batteries, are batteries that can be recharged to activate the active material after the battery is discharged and continue to be used. Rechargeable batteries are widely used in electronic devices such as mobile phones, laptops, battery cars, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and electric tools, etc.

[0003] The rechargeable battery may include a nickel-cadmium battery, a nickel-hydrogen battery, a lithium-ion battery, a secondary alkaline zinc-manganese battery, and the like.

[0004] At present, the batteries used most in automobiles are generally lithium-ion batteries. As a rechargeable battery, lithium-ion batteries have the advantages of small size, high energy density, high power density, many cycles and long storage time.

[0005] A rechargeable battery includes an electrode assembly and an electrolyte solution, wherein the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet may also be referred to as a cathode sheet, and both surfaces of the positive electrode sheet 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; the negative electrode sheet may also be referred to as an anode sheet, and both surfaces of the negative electrode sheet 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.

[0006] Lithium plating is a common abnormal phenomenon in lithium batteries, which will affect the charging efficiency and energy density of lithium ions. When lithium plating is severe, lithium crystals can form. Lithium crystals can pierce the isolation membrane and cause internal short circuit thermal runaway, seriously endangering the safety of the battery.

[0007] Therefore, how to reduce or avoid lithium plating and improve battery safety has become a difficult problem in the industry. Summary of the invention

[0008] Various aspects of the present application provide an electrode assembly, a battery cell, a battery, and a method and apparatus for manufacturing an electrode assembly, which overcome the above problems or at least partially solve the above problems.

[0009] A first aspect of the present application provides an electrode assembly, comprising: a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet and the negative electrode sheet are wound or stacked to form a bending area;

[0010] The bend region has a barrier layer, wherein at least a portion of the barrier layer is located between adjacent positive and negative electrode sheets, and is used to block at least a portion of ions released from the positive electrode sheet from being embedded in the negative electrode sheet in the bend region. By providing a barrier layer between adjacent positive and negative electrode sheets, during charging, at least a portion of ions released from the positive active material layer of the positive electrode sheet in the bend region are blocked by the barrier layer, so that the ions blocked by the barrier layer cannot be embedded in the negative active material layer of the negative electrode sheet adjacent to the positive electrode sheet in the bend region, so that when the negative active material of the negative electrode sheet falls off, the occurrence of lithium precipitation is reduced, the safety performance of the battery cell is improved, and the service life of the battery cell is improved.

[0011] In some embodiments, the electrode assembly further includes a separator for isolating adjacent positive and negative electrode sheets, a barrier layer is attached to one or both surfaces of the positive electrode sheet, and / or a barrier layer is attached to one or both surfaces of the negative electrode sheet, and / or a barrier layer is attached to one or both surfaces of the separator. In this way, the positional movement of the barrier layer during use of the electrode assembly can be reduced.

[0012] In some embodiments, the electrode assembly further includes a separator for isolating adjacent positive and negative electrode sheets, and the barrier layer is independent of the positive electrode sheets and the separator adjacent to the bending region, or the barrier layer is independent of the negative electrode sheets and the separator adjacent to the bending region. In this way, the installation of the barrier layer can be facilitated.

[0013] In some embodiments, the porosity of the barrier layer is less than the porosity of the separator, so that the barrier layer can more effectively block the passage of lithium ions.

[0014] In some embodiments, the electrode assembly includes a positive electrode sheet and a negative electrode sheet, and the positive electrode sheet and the negative electrode sheet are compacted and wound to form a winding structure, wherein a barrier layer is provided between at least the innermost adjacent positive electrode sheet and the negative electrode sheet in the bending region. In this way, the lithium deposition phenomenon between the innermost adjacent positive electrode sheet and the negative electrode sheet can be reduced, thereby improving the safety performance.

[0015] In some embodiments, the innermost electrode sheet of the bending area is the negative electrode sheet, so that the utilization efficiency of the active material of the positive electrode sheet can be improved.

[0016] In some embodiments, the barrier layer is a plurality of discontinuous barrier layers, which are spaced apart along the bending direction, or spaced apart along a direction perpendicular to the bending direction. In this way, the passage of some lithium ions can be blocked to reduce the occurrence of lithium precipitation, while the energy density of the electrode assembly can be ensured.

[0017] In some embodiments, the thickness of the barrier layer is 2-200 microns; or 5-100 microns. In this way, both the safety and energy density of the electrode assembly can be ensured.

[0018] In some embodiments, the barrier layer has at least one through hole.

[0019] In some embodiments, the porosity of the barrier layer is 10%-70%; or 20%-60%. In this way, both the safety and energy density of the electrode assembly can be ensured.

[0020] In some embodiments, the thickness of the barrier layer is A micrometers, and the porosity of the barrier layer is B, wherein A and B satisfy the following relationship: 3.5 micrometers ≤ A / B ≤ 2000 micrometers; or 7 micrometers ≤ A / B ≤ 1000 micrometers. In this way, both the safety and energy density of the electrode assembly can be ensured.

[0021] In some embodiments, both ends of the negative active material layer of the negative electrode sheet along the direction perpendicular to the bending direction extend beyond the corresponding ends of the positive active material layer of the positive electrode sheet. In this way, the energy density of the electrode assembly can be ensured.

[0022] In some embodiments, the barrier layer includes two ends perpendicular to the bending direction, and one or both ends of the barrier layer extend beyond the positive electrode active material layer of the positive electrode sheet, so that more lithium ions can be blocked from passing through, reducing the occurrence of lithium precipitation.

[0023] In some embodiments, the barrier layer includes two ends perpendicular to the bending direction, and the negative electrode active material layer of the negative electrode plate extends beyond one or both ends of the barrier layer. In this way, it can block the passage of some lithium ions and reduce the occurrence of lithium deposition, while ensuring the energy density of the electrode assembly.

[0024] In some embodiments, the barrier layer is disposed opposite to the portion of the negative electrode sheet with the largest curvature, so that the portion with the largest curvature does not embed lithium ions or embeds a small number of lithium ions, thereby reducing the occurrence of lithium precipitation.

[0025] In some embodiments, the barrier layer includes at least one of an inorganic oxide, a binder, and a tape.

[0026] In some embodiments, both ends of the barrier layer extending along the bending direction are located in the bending region, so that more lithium ions can be blocked from passing through and the occurrence of lithium deposition can be reduced.

[0027] In some embodiments, the electrode assembly has a straight region connected to a bent region;

[0028] One end of the barrier layer extending along the bending direction is located in the straight region, and the other end is located in the bending region; or, both ends of the barrier layer extending along the bending direction are located in the straight region.

[0029] A second aspect of the present application provides a battery cell, which includes: a housing, a cover plate, and at least one electrode assembly according to the above embodiment, wherein:

[0030] The shell has a receiving cavity and an opening, and the electrode assembly is received in the receiving cavity;

[0031] The cover plate is used to close the opening of the housing.

[0032] A third aspect of the present application provides a battery, which includes a box and at least one battery cell, wherein the battery cell is accommodated in the box.

[0033] A fourth aspect of the present application provides a method for manufacturing an electrode assembly, comprising:

[0034] Providing positive electrode sheets, negative electrode sheets and barrier layers;

[0035] The positive electrode sheet and the negative electrode sheet are wound or stacked to form a bending zone, wherein a barrier layer is provided in the bending zone, wherein at least a portion of the barrier layer is located between adjacent positive electrode sheets and negative electrode sheets, and is used to block at least a portion of ions escaped from the positive electrode sheet from being embedded in the negative electrode sheet in the bending zone.

[0036] In some embodiments, a separator is provided for separating adjacent positive electrode sheets and negative electrode sheets, and the separator, the positive electrode sheets, and the negative electrode sheets are wound or stacked together.

[0037] In some embodiments, before winding or stacking the separator, the positive electrode sheet, and the negative electrode sheet together, the method further includes: placing a barrier layer on one or both surfaces of the positive electrode sheet or the negative electrode sheet.

[0038] In some embodiments, placing the barrier layer on one or both surfaces of the positive electrode sheet or the negative electrode sheet specifically includes: pasting or coating the barrier layer on one or both surfaces of the positive electrode sheet or the negative electrode sheet.

[0039] A fifth aspect of the present application provides a manufacturing device for an electrode assembly, comprising:

[0040] A first providing device, for providing a positive electrode sheet;

[0041] A second providing device, used for providing a negative electrode sheet;

[0042] A third providing device for providing a barrier layer;

[0043] An assembly device for winding or stacking the positive electrode sheet and the negative electrode sheet to form a bending area;

[0044] There is a barrier layer in the bending area, wherein at least a portion of the barrier layer is located between adjacent positive electrode sheets and negative electrode sheets, and is used to block at least a portion of ions escaped from the positive electrode sheet from being embedded in the negative electrode sheet in the bending area.

[0045] In some embodiments, the manufacturing equipment of the electrode assembly also includes a fourth providing device for providing an isolation film for separating adjacent positive electrode sheets and negative electrode sheets, and the assembling device is also used to form a bending area by winding or stacking the positive electrode sheets, negative electrode sheets and isolation films.

[0046] In some embodiments, there are two third providing devices, and the two third providing devices are used to respectively provide a barrier layer, and to stick or coat the barrier layer on the two surfaces of the positive electrode sheet or the negative electrode sheet.

[0047] A sixth aspect of the present application provides an electric device, wherein the electric device is configured to receive electric power provided by a battery.

[0048] The above description is only an overview of the technical solution of the embodiment of the present application. In order to more clearly understand the technical means of the embodiment of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0050] Figure 1 A schematic diagram of the three-dimensional structure of an electrode assembly according to an embodiment of the present application;

[0051] Figure 2 for Figure 1 A schematic structural diagram of a cross section of an electrode assembly along a direction perpendicular to a winding axis K;

[0052] Figure 3 This is a schematic diagram of the local structure of an electrode assembly in a bending area according to an embodiment of the present application;

[0053] Figure 4 This is a schematic structural diagram of the barrier layer distribution after the bending area of ​​the electrode assembly of another embodiment of the present application is flattened;

[0054] Figure 5It is a structural schematic diagram of another barrier layer distribution after the bending area of ​​the electrode assembly of another embodiment of the present application is flattened;

[0055] Figure 6 It is a structural schematic diagram of another barrier layer distribution after the bending area of ​​the electrode assembly of another embodiment of the present application is flattened;

[0056] Figure 7 This is a schematic structural diagram of a negative electrode sheet according to another embodiment of the present application;

[0057] Figure 8 This is a schematic structural diagram of a positive electrode sheet in another embodiment of the present application;

[0058] Fig. 9 for Figure 8 Schematic diagram of the cross-sectional structure along the AA direction;

[0059] Fig.10 for Figure 8 Schematic diagram of the cross-sectional structure along the BB direction;

[0060] Fig.11 This is a schematic structural diagram of a cross section of a flat electrode assembly perpendicular to the winding axis in another embodiment of the present application;

[0061] Fig.12 This is a schematic structural diagram of a cross section of another flat electrode assembly perpendicular to the winding axis in another embodiment of the present application;

[0062] Fig.13 This is a schematic structural diagram of a cross section of another flat electrode assembly perpendicular to the winding axis in another embodiment of the present application;

[0063] Fig.14 This is a schematic structural diagram of a cross section of another flat electrode assembly perpendicular to the winding axis in another embodiment of the present application;

[0064] Fig.15 This is a schematic structural diagram of a cross section of another flat electrode assembly perpendicular to the winding axis in another embodiment of the present application;

[0065] Fig.16 This is a schematic structural diagram of a cross section of another flat electrode assembly perpendicular to the winding axis in another embodiment of the present application;

[0066] Fig.17 This is a schematic structural diagram of a cross section of another flat electrode assembly perpendicular to the winding axis in another embodiment of the present application;

[0067] Fig.18This is a schematic structural diagram of a cross section of a flat electrode assembly perpendicular to the winding axis in another embodiment of the present application;

[0068] Fig.19 This is a schematic structural diagram of a cross section of a flat electrode assembly perpendicular to the winding axis in another embodiment of the present application;

[0069] Fig. 20 This is a schematic structural diagram of a battery cell according to another embodiment of the present application;

[0070] Fig.21 This is a schematic structural diagram of a battery module according to another embodiment of the present application;

[0071] Fig. 22 A schematic diagram of the structure of a battery according to another embodiment of the present application;

[0072] Fig.23 This is a schematic structural diagram of an electrical device according to another embodiment of the present application;

[0073] Fig.24 A schematic flow chart of a method for manufacturing an electrode assembly according to another embodiment of the present application;

[0074] Fig.25 This is a schematic diagram of the structure of a manufacturing equipment for an electrode assembly according to another embodiment of the present application. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0076] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0077] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0078] The term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0079] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. in the specification and claims of the present application or the above-mentioned drawings are used to distinguish different objects, rather than 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, "multiple" means two or more.

[0080] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0081] In order to make the lithium-ion battery smaller and higher in energy density, the positive electrode sheet, the negative electrode sheet and the separator in the electrode assembly of the lithium-ion battery can be wound and then compacted. Figure 1As shown, it is a schematic diagram of the three-dimensional structure of an electrode assembly, which includes a negative electrode sheet, a positive electrode sheet and a separator, wherein the negative electrode sheet, the positive electrode sheet and the separator are stacked and wound around a winding axis K to form a winding structure, and the separator is an insulating film used to separate the negative electrode sheet and the positive electrode sheet to prevent the negative electrode sheet and the positive electrode sheet from short-circuiting. The winding structure of the electrode assembly is a flat body shape, and the schematic diagram of the structure of the cross section of the electrode assembly along the direction perpendicular to the winding axis K can be as shown Figure 2 shown.

[0082] Combination Figure 1 and Figure 2 , the electrode assembly includes a straight region 100 and bending regions 200 located at both ends of the straight region 100. The straight region 100 refers to a region with a parallel structure in the winding structure, that is, the negative electrode sheet 101, the positive electrode sheet 102 and the separator 103 in the straight region 100 are substantially parallel to each other, that is, the surfaces of each layer of the negative electrode sheet 101, the positive electrode sheet 102 and the separator 103 of the electrode assembly in the straight region 100 are all flat. The bending zone 200 refers to an area with a bending structure in the winding structure, that is, the negative electrode sheet 101, the positive electrode sheet 102 and the isolation film 103 in the bending zone 200 are all bent, that is, the surfaces of each layer of the negative electrode sheet 101, the positive electrode sheet 102 and the isolation film 103 of the electrode assembly in the bending zone 200 are all curved surfaces, and the bending zone 200 has a bending direction L. The bending direction L can be understood as the direction pointing to the straight area along the surface of the electrode assembly in the bending zone, for example, the bending direction L is in the bending zone 200 along the winding direction of the winding structure.

[0083] The surface of the negative electrode plate 101 has a negative electrode active material layer composed of a negative electrode active material, and the surface of the positive electrode plate 102 has a positive electrode active material layer composed of a positive electrode active material. For example, the positive electrode active material can be lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate or nickel cobalt lithium manganese oxide, and the negative electrode active material can be graphite or silicon.

[0084] When a lithium-ion battery is charged, lithium ions are deintercalated from the positive electrode and embedded in the negative electrode, but some abnormal situations may occur, such as insufficient lithium embedding space in the negative electrode, too much resistance for lithium ions to embed in the negative electrode, or too fast deintercalation of lithium ions from the positive electrode. The deintercalated lithium ions cannot be equally embedded in the negative electrode active material layer of the negative electrode plate. The lithium ions that cannot be embedded in the negative electrode plate can only obtain electrons on the surface of the negative electrode, thereby forming a silvery-white metallic lithium single substance, which is the lithium precipitation phenomenon. Lithium precipitation not only reduces the performance of lithium-ion batteries and greatly shortens the cycle life, but also limits the fast charging capacity of lithium-ion batteries. In addition, when lithium ion batteries undergo lithium precipitation, the precipitated lithium metal is very active and can react with the electrolyte at a lower temperature, causing the battery's self-heating starting temperature (Tonset) to decrease and the self-heating rate to increase, seriously endangering the safety of the battery. Furthermore, when lithium precipitation is severe, the deintercalated lithium ions can form lithium crystals on the surface of the negative electrode plate, and the lithium crystals can easily puncture the isolation membrane, causing the adjacent positive and negative electrode plates to have the risk of short circuit.

[0085] During the research and development process, the inventor discovered that lithium deposition often occurs in the bending area of ​​the electrode assembly. After further research, the inventor found that the cause of the lithium deposition is the shedding of active materials. This is mainly because the negative active material is coated on the surface of the negative electrode sheet, and the positive active material is coated on the surface of the positive electrode sheet. The positive and negative electrode sheets located in the turning area need to be bent, so their respective active materials may fall off, which is called powder loss. In particular, the innermost sheet in the bending area has the greatest degree of bending, which is more likely to cause active material shedding. Due to the shedding of active materials, especially the shedding of active materials on the negative electrode sheet, the number of lithium ions that can be provided by the negative active material layer of the negative electrode sheet may be less than that of the positive active material layer of the adjacent positive electrode sheet. Therefore, lithium deposition is prone to occur when the lithium battery is charged.

[0086] In view of this, the present application intends to provide an electrode assembly, which includes a negative electrode sheet, a positive electrode sheet and a separator, wherein the negative electrode sheet, the positive electrode sheet and the separator can be stacked to form a winding structure around a winding axis, for example, a flat winding structure, and the negative electrode sheet, the positive electrode sheet and the separator can be stacked to form a Z-shaped continuous folding. Regardless of whether the electrode assembly is formed by winding or by continuous folding in a Z-shape, the electrode assembly includes a straight area and a bending area connecting the two ends of the straight area. In order to reduce or avoid lithium deposition, any adjacent positive electrode sheet in the bending area A barrier layer is arranged between the positive electrode sheet and the negative electrode sheet, especially between the adjacent positive electrode sheet and the negative electrode sheet at the innermost side of the bending zone, and the barrier layer is used to block at least a part of the lithium ions released from the positive active material layer of the positive electrode sheet in the bending zone, so that the ions blocked by the barrier layer cannot be embedded in the negative active material layer of the negative electrode sheet adjacent to the positive electrode sheet in the bending zone, so that the lithium insertion site of the negative active material layer of the negative electrode sheet in the bending zone is basically the same as the number of lithium ions that can be provided by the positive active material layer of the adjacent positive electrode sheet, so the occurrence of lithium precipitation can be reduced or avoided.

[0087] Regardless of whether the electrode assembly is formed by winding or by continuous folding in a Z shape, the electrode assembly includes a straight area and a bending area connecting the two ends of the straight area. For the sake of simplicity, the electrode assembly of this embodiment is described by taking a flat body winding structure as an example. For example, the structure of one of the bending areas C and the straight area P of the flat body winding structure can be as follows: Figure 3 As shown, it is a schematic diagram of the local structure of an electrode assembly in a bending area of ​​an embodiment of the present application, wherein the electrode assembly includes a positive electrode sheet 1, a negative electrode sheet 2 and an isolation membrane 3 for isolating the positive electrode sheet 1 and the negative electrode sheet 2 in its bending area C, wherein the isolation membrane 3 can be independent of the adjacent positive electrode sheet 1 and the negative electrode sheet 2, or can be coated on the surface of the positive electrode sheet 1 or the negative electrode sheet 2.

[0088] The separator 3 has electronic insulation and is used to isolate the adjacent positive electrode sheet 1 and negative electrode sheet 2 to prevent the adjacent positive electrode sheet 1 and negative electrode sheet 2 from short-circuiting. The separator 3 has a large number of through micropores, which can ensure the free passage of electrolyte ions and has good permeability to lithium ions. Therefore, the separator 3 basically cannot block the passage of lithium ions. For example, the separator 3 includes a separator base layer and a functional layer located on the surface of the separator base layer. The separator base layer can be at least one of polypropylene, polyethylene, ethylene-propylene copolymer, polybutylene terephthalate, etc., and the functional layer can be a mixture layer of ceramic oxide and binder.

[0089] The electrode assembly of an embodiment of the present application further has a blocking layer 4 in its bending zone C, wherein at least a portion of the blocking layer 4 is located between the adjacent positive electrode sheet 1 and the negative electrode sheet 2, and is used to block at least a portion of the ions escaped from the positive electrode sheet 1 from being embedded in the negative electrode sheet 2 in the bending zone C.

[0090] By providing a barrier layer 4 between the adjacent positive electrode sheet 1 and negative electrode sheet 2 in the bending area C, the lithium precipitation phenomenon can be effectively reduced or avoided. A barrier layer 4 is provided between the adjacent positive electrode sheet 1 and negative electrode sheet 2. During charging, at least a portion of the ions released from the positive active material layer of the positive electrode sheet 1 (for example, the positive active material layer in the bending area C) are blocked by the barrier layer 4, so that the ions blocked by the barrier layer 4 cannot be embedded in the negative active material layer of the negative electrode sheet 2 in the bending area C, so that when the negative active material of the negative electrode sheet 2 falls off, the occurrence of lithium precipitation is reduced, that is, although the negative electrode sheet 2 has a reduced lithium insertion site due to the falling off of the negative active material, the barrier layer 4 blocks at least a portion of the lithium ions released from the positive electrode sheet 1 adjacent to the negative electrode sheet 2, so the occurrence of lithium precipitation can be reduced or even avoided.

[0091] In another embodiment of the present application, in order to block the passage of lithium ions, the barrier layer 4 may be made of an inorganic oxide and / or a high molecular polymer.

[0092] In another embodiment of the present application, the inorganic oxide may be at least one of magnesium oxide (MgO), calcium oxide (CaO), boehmite, wollastonite, barium sulfate (BaSO4), calcium sulfate (CaSO4), calcium carbonate (CaCO3), aluminum oxide (Al2O3) and silicon dioxide (SiO2).

[0093] In another embodiment of the present application, the high molecular polymer may be at least one of polypropylene, polyvinyl chloride (PVC), polyethylene (PE), epoxy resin, polyacrylate and polyurethane rubber.

[0094] In another embodiment of the present application, the barrier layer 4 may be a tape or adhesive paper. The tape includes an adhesive and a substrate, wherein the substrate may be made of polyethylene and / or ethylene-vinyl acetate copolymer (EVA). The material of the adhesive paper includes at least one of polyethylene terephthalate, polyvinylidene fluoride, polyurethane, sodium polyacrylate, styrene-butadiene rubber, polyetherimide, carboxymethyl cellulose and acrylate.

[0095] In another embodiment of the present application, a positive electrode sheet 1 and a negative electrode sheet 2 may be stacked and then wound or folded, or at least one (for example, two or more) positive electrode sheet 1 and at least one (for example, two or more) negative electrode sheet 2 may be stacked and then wound or folded to form a bending area C. When the electrode assembly has multiple layers of positive electrode sheets 1 and multiple layers of negative electrode sheets 2 in the bending area C, the bending area C includes a structure in which the positive electrode sheets 1 and the negative electrode sheets 2 are alternately distributed, and a barrier layer 4 is included between at least one adjacent layer of the positive electrode sheet 1 and the negative electrode sheet 2. The adjacent positive electrode sheet 1 and the negative electrode sheet 2 in the bending area C refer to a layer of positive electrode sheet 1 and a layer of negative electrode sheet 2 adjacent to each other in the bending area C, and no other layer of positive electrode sheet 1 or another layer of negative electrode sheet 2 is included between them.

[0096] In another embodiment of the present application, in addition to the structure in which the positive electrode sheets 1 and the negative electrode sheets 2 are alternately distributed, the bending zone C (for example, the innermost and / or outermost side of the bending zone C) may also have a structure in which no negative electrode sheet 2 exists between two adjacent layers of positive electrode sheets 1, or a structure in which no positive electrode sheet 1 exists between two adjacent layers of negative electrode sheets 2. In this case, a barrier layer 4 may not be provided between the two adjacent layers of positive electrode sheets 1 or the two adjacent layers of negative electrode sheets 2, that is, the barrier layer 4 is provided between the adjacent positive electrode sheets 1 and the negative electrode sheets 2.

[0097] In another embodiment of the present application, the electrode assembly is generally the one with the largest bending degree at the innermost pole piece in the bending zone C, that is, the probability of active material shedding of the innermost pole piece is the largest or the active material shedding is the most serious, and the innermost pole piece may be the positive pole piece 1 or the negative pole piece 2. For example, when the innermost pole piece is the negative pole piece 2, in order to minimize the occurrence of lithium deposition, there is a barrier layer 4 between at least the innermost adjacent positive pole piece 1 and the negative pole piece 2 in the bending zone C. In this way, the lithium deposition phenomenon between the innermost adjacent positive pole piece and the negative pole piece can be reduced, and the safety performance can be improved. When the innermost pole piece in the bending zone C is the negative pole piece 2, the utilization efficiency of the active material of the positive pole piece 1 can be improved.

[0098] Wherein, the barrier layer 4 is located between the adjacent positive electrode sheet 1 and the negative electrode sheet 2, and the barrier layer 4 can be independently located between the adjacent positive electrode sheet 1 and the negative electrode sheet 2, or the barrier layer 4 can be attached to any surface of the positive electrode sheet 1, the negative electrode sheet 2 or the separator 3. Wherein, the barrier layer 4 is independently located between the adjacent positive electrode sheet 1 and the negative electrode sheet 2, which means that the barrier layer 4 is separately stacked with the positive electrode sheet 1 and the negative electrode sheet 2, that is, there is no adhesion or coating relationship, which is conducive to the installation of the barrier layer 4; and attachment refers to adhesion or coating or spraying, and through attachment, the position movement of the barrier layer 4 during the use of the battery cell can be reduced.

[0099] For example, the barrier layer 4 is attached to one surface or both surfaces of the positive electrode sheet 1 , and / or the barrier layer 4 is attached to one surface or both surfaces of the negative electrode sheet 2 .

[0100] In another embodiment of the present application, the barrier layer 4 is independent between the adjacent positive electrode sheet 1 and the separator 3 in the bending zone C, or the barrier layer 4 is independent between the adjacent negative electrode sheet 2 and the separator 3 in the bending zone C, or the barrier layer 4 is attached to one surface or both surfaces of the separator 3. The barrier layer 4 is independent between the adjacent positive electrode sheet 1 and the separator 3 in the bending zone C, or the barrier layer 4 is independent between the adjacent negative electrode sheet 2 and the separator 3 in the bending zone C, which means that the barrier layer 4 is separately stacked with the positive electrode sheet 1, the negative electrode sheet 2 and the separator 3, that is, it has no adhesion or coating relationship.

[0101] In another embodiment of the present application, both ends of the barrier layer 4 extending along the bending direction L are located in the bending zone C, that is, the barrier layer 4 is entirely located in the bending zone C. In this embodiment, the electrode assembly further includes a straight zone P connected to the bending zone C, the bending direction L refers to a direction along the curved surface of the bending zone C and pointing to the straight zone P, and the direction perpendicular to the bending direction L refers to a direction perpendicular to the bending direction L.

[0102] In another embodiment of the present application, one end of the barrier layer 4 extending along the bending direction L is located in the straight region P, and the other end is located in the bending region C.

[0103] In another embodiment of the present application, in order to block as many lithium ions as possible, the blocking layer 4 has as large an area as possible in the bending zone C. For example, both ends of the blocking layer 4 extending along the bending direction L are located in the straight zone P, that is, in addition to being located in the bending zone C, the blocking layer 4 also extends to the straight zone P.

[0104] In another embodiment of the present application, both ends of the barrier layer 4 extending along the bending direction L are located at the junction of the bending area C and the straight area P, or both ends of the barrier layer 4 extending along the bending direction L are close to the junction of the bending area C and the straight area P.

[0105] In another embodiment of the present application, when the negative electrode sheet 2 is located at the innermost side of the bending zone C, the negative electrode active material is most seriously shed at the part with the largest curvature of the innermost negative electrode sheet 2. Therefore, no matter how the barrier layer 4 extends along the bending direction L, the barrier layer 4 blocks the lithium ions released from the positive electrode sheet 1 from being embedded in the part with the largest curvature of the negative electrode sheet 2 as much as possible, that is, the barrier layer 4 is arranged relative to the part with the largest curvature of the negative electrode sheet 2, and is used to cover the part with the largest curvature of the negative electrode sheet 2. In this way, the part with the largest curvature of the negative electrode sheet 2 can be free of lithium ions or embedded with a small amount of lithium ions, thereby reducing the occurrence of lithium precipitation.

[0106] In another embodiment of the present application, the part of the negative electrode sheet 2 at the innermost side of the bending zone C with the largest curvature is a line (for example, the line may be a straight line) on the curved surface of the negative electrode sheet 2 at the innermost side of the bending zone C along a line perpendicular to the bending direction L, and the curvature of any point on the line is greater than the curvature of the curved surface of the negative electrode sheet 2 at the innermost side of the bending zone C on both sides of the point along the bending direction L. For example, when the negative electrode sheet 2 is symmetrically bent along the bending direction L in the bending zone C, the part of the negative electrode sheet 2 at the innermost side of the bending zone C with the largest curvature is the middle part of the negative electrode sheet 2 in the bending zone C.

[0107] Although the blocking layer 4 can block more lithium ions as its area in the bending zone C increases, the more lithium ions it blocks, the lower the energy density of the bending zone C, resulting in a lower energy density of the electrode assembly. Therefore, in another embodiment of the present application, for the adjacent positive electrode sheet 1 and negative electrode sheet 2 in the bending zone C, lithium ions can be appropriately allowed to escape from the positive electrode sheet 1 and embed into the negative electrode sheet 2 to ensure a certain energy density.

[0108] For example, Figure 4 As shown, it is a schematic structural diagram of the barrier layer distribution after the bending area C of the electrode assembly of another embodiment of the present application is flattened. A plurality of discontinuous barrier layers 4 are included between the adjacent positive electrode sheet 1 and the negative electrode sheet 2 in the bending area C. The plurality of discontinuous barrier layers 4 are spaced along the bending direction L, so that some lithium ions are not blocked by the barrier layer 4, that is, some lithium ions pass through between two adjacent barrier layers 4 and are embedded in the negative active material layer of the negative electrode sheet 2. For example, a plurality of discontinuous barrier layers 4 are attached to the surface of the positive electrode sheet 1. In this way, it is possible to block the passage of some lithium ions, reduce the occurrence of lithium precipitation, and ensure the energy density of the electrode assembly.

[0109] For example, Figure 5 As shown, it is a schematic structural diagram of another barrier layer distribution after the bending zone of the electrode assembly of another embodiment of the present application is flattened, and a plurality of discontinuous barrier layers 4 are included between the adjacent positive electrode sheets 1 and negative electrode sheets 2 in the bending zone, and the plurality of discontinuous barrier layers 4 are spaced apart along the K direction perpendicular to the bending direction L, so that some lithium ions are not blocked by the barrier layer 4, that is, some lithium ions pass through between two adjacent barrier layers 4 and are embedded in the negative active material layer of the negative electrode sheet 2. For example, a plurality of discontinuous barrier layers 4 are attached to the surface of the positive electrode sheet 1. Among them, the K direction perpendicular to the bending direction L can be the width direction of the positive electrode sheet 1 and the negative electrode sheet 2. When the electrode assembly is a winding structure, the K direction perpendicular to the bending direction L is the winding axis direction of the winding structure.

[0110] For example, Figure 6As shown, it is a structural schematic diagram of another barrier layer distribution after the bending area of ​​the electrode assembly of another embodiment of the present application is flattened, the barrier layer 4 is attached to the surface of the positive electrode plate 1, and the barrier layer 4 has at least one through hole 41 for partial lithium ions to pass through and embed into the negative electrode active material layer of the negative electrode plate 2.

[0111] In another embodiment of the present application, the porosity of the barrier layer 4 is less than the porosity of the separator 3, so that the barrier layer 4 can more effectively block the passage of lithium ions. Porosity refers to the percentage of the pore volume in the bulk material to the total volume of the material in its natural state. In general, the test method for porosity is the true density test method.

[0112] In order to achieve a better balance between blocking lithium ions and maintaining energy density, the thickness of the barrier layer 4 is A micrometers, and the porosity of the barrier layer 4 is B, wherein A and B satisfy the following relationship: 3.5 micrometers ≤ A / B ≤ 2000 micrometers, optionally, 7 micrometers ≤ A / B ≤ 1000 micrometers. In this way, both the safety of the electrode assembly and the energy density of the electrode assembly can be guaranteed, and a better balance can be achieved between safety performance and energy density. If A is too small, it means that the thickness of the barrier layer 4 is too small, and lithium crystals can easily puncture the barrier layer 4, or even puncture the separator 3, so that the barrier layer 4 loses its function of blocking lithium ions, and there may be safety risks; if B is large, it means that the porosity of the barrier layer 4 is too large. The larger the porosity of the barrier layer 4, the more lithium ions pass through the protective layer 4, which may lead to serious lithium precipitation. For example, when A / B is less than 3.5, it means that A is small, that is, the thickness of the barrier layer 4 is too small, and B is large, that is, the porosity of the barrier layer 4 is too large, and the barrier layer 4 loses its function of blocking lithium ions, and there may be safety risks. When A / B is greater than 2000, A is larger, that is, the thickness of the barrier layer 4 is too large, and B is smaller, that is, the porosity of the barrier layer 4 is too small, which seriously affects the energy density of the battery cell.

[0113] 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, both the safety of the electrode assembly and the energy density of the electrode assembly can be guaranteed, and a good balance can be achieved between safety performance and energy density. For example, when the thickness of the barrier layer 4 is less than 2um, the thickness of the barrier layer 4 is too small. When lithium precipitation is serious, lithium crystals will pierce the barrier layer 4, and even pierce the isolation film 3, so that the barrier layer 4 loses its function of blocking lithium ions, and there is a safety risk. When the thickness of the barrier layer 4 is greater than 500um, the thickness of the barrier layer 4 is relatively large, resulting in a large gap between the adjacent positive electrode sheet 1 and the negative electrode sheet 2. The barrier layer 4 occupies space, which may affect the energy density of the electrode assembly. Moreover, the gap between the two adjacent layers is too large, which may seriously affect the cycle performance.

[0114] 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, both the safety and energy density of the electrode assembly can be guaranteed, and a good balance can be achieved between safety performance and energy density. For example, when the porosity is less than 10%, most or all of the lithium ions will be blocked by the barrier layer 4 and cannot be embedded in the negative electrode plate 2, thereby affecting the energy density of the electrode assembly; and when the porosity is greater than 70%, most or almost all of the lithium ions will pass through the barrier layer 4, and there will be a risk of lithium precipitation, resulting in lithium crystals piercing the barrier layer 4, so that the barrier layer 4 loses its function of blocking lithium ions, and there is a safety risk.

[0115] When the electrode assembly has a winding structure, the width direction of the positive electrode sheet 1 and the negative electrode sheet 2 is parallel to the winding axis direction, and the width direction of the positive electrode sheet 1 and the negative electrode sheet 2 is parallel to the direction perpendicular to the bending direction L; when the electrode assembly does not have a winding structure, the width direction of the positive electrode sheet 1 and the negative electrode sheet 2 is parallel to the direction perpendicular to the bending direction L. For the simplicity of subsequent description, in this embodiment, the width direction of the positive electrode sheet 1 and the negative electrode sheet 2, the direction perpendicular to the bending direction L and the winding axis direction are collectively referred to as the K direction.

[0116] The structure of the negative electrode plate 2 can be Figure 7 As shown, it is a schematic diagram of the structure of a negative electrode plate of another embodiment of the present application, the negative electrode plate 2 includes a negative electrode main body 21 and a negative electrode ear 22 extending outward from the negative electrode main body 21 along the K direction, and at least a portion of the area along the K direction on the surface of the negative electrode main body 21 is a negative electrode active material area 211, and the negative electrode active material area 211 is used to coat the negative electrode active material, and the negative electrode active material can be graphite or silicon.

[0117] In another embodiment of the present application, not only is a negative electrode active material region 211 provided on a partial area of ​​the surface of the negative electrode main body 21, but a negative electrode active material region 211 is also provided on the surface of the negative electrode ear 22 and in a root area close to the negative electrode main body 21, that is, a partial area of ​​the negative electrode ear 22 is the negative electrode active material region 211.

[0118] In another embodiment of the present application, Figure 7 As shown, the negative electrode active material region 211 covers the entire surface of the negative electrode body portion 21 along the direction K.

[0119] 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, Figure 8 , which is a schematic structural diagram of a positive electrode plate in another embodiment of the present application.

[0120] The positive electrode plate 1 includes a positive electrode main body 11 and at least one positive electrode ear 12 extending outside the positive electrode main body 11 along the K direction. At least a part of the surface of the positive electrode main body 11 is a positive electrode active material area 111, and the positive electrode active material area 111 can be coated with a positive electrode active material. For example, the positive electrode active material can be a ternary material, lithium manganese oxide or lithium iron phosphate.

[0121] In another embodiment of the present application, the surface of the positive electrode main body 11 further includes a first insulating layer coating area 112 adjacent to the positive electrode active material area 111, and the first insulating layer coating area 112 is located on the side of the positive electrode active material area 111 adjacent to the positive electrode ear 12, and the first insulating layer coating area 112 is used to coat an insulating material for insulating and isolating the positive electrode active material area 111 and the positive electrode ear 12, for example, Fig. 9 As shown, Figure 8 The schematic diagram of the cross-sectional structure along the AA direction shows that the two surfaces of the current collector 10 of the positive electrode plate 1 have positive electrode active material areas 111 , and the positive electrode ear 12 is a part of the current collector 10 of the positive electrode plate 1 , wherein the material of the current collector 10 can be aluminum.

[0122] For example, the positive electrode active material area 111 and the first insulating layer coating area 112 are distributed at both ends of the surface of the positive electrode main body 11 along the width direction (i.e., K direction) of the positive electrode main body 11, and the positive electrode ear 12 and the first insulating layer coating area 112 belong to the same end of the positive electrode main body 11.

[0123] In another embodiment of the present application, the positive electrode active material region 111 and the first insulating layer coating region 112 are two substantially parallel regions on the surface of the positive electrode body 11 and are distributed in two layers along the K direction on the surface of the positive electrode body 11 .

[0124] In another embodiment of the present application, the first insulating layer coating area 112 may be located at a portion where the positive electrode body 11 and the positive electrode ear 12 are connected to each other. For example, the first insulating layer coating area 112 is located on the surface of the positive electrode body 11 and is connected to the positive electrode ear 12, and is used to separate the surface of the positive electrode ear 12 from the positive electrode active material area 111. In another embodiment of the present application, not only is the first insulating layer coating area 112 provided on the surface of the positive electrode body 11, but a second insulating layer coating area 121 is also provided in the root area of ​​the positive electrode ear 12 close to the positive electrode body 11, and the second insulating layer coating area 121 is used to coat an insulating material.

[0125] In another embodiment of the present application, the surface of the first insulating layer coating area 112 is coated with an insulating material, and the insulating material includes an inorganic filler and an adhesive. The inorganic filler includes one or more of boehmite, aluminum oxide, magnesium oxide, titanium dioxide, zirconium oxide, silicon dioxide, silicon carbide, boron carbide, calcium carbonate, aluminum silicate, calcium silicate, potassium titanate, and barium sulfate. The adhesive includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyacrylic acid, polyacrylate, polyacrylic acid-acrylate, polyacrylonitrile-acrylic acid, and polyacrylonitrile-acrylate.

[0126] In another embodiment of the present application, each positive electrode plate 1 may include one or two or more positive electrode ears 12. When the positive electrode plate 1 includes two or more positive electrode ears 12, all the positive electrode ears 12 are located on the same side of the positive electrode plate 1 along the K direction.

[0127] Combination Figure 7 and Figure 8 When the positive electrode sheet 1 and the negative electrode sheet 2 are stacked on each other, both ends of the negative active material region 211 of the negative electrode sheet 2 along the direction K exceed the corresponding ends of the positive active material region 111 of the adjacent positive electrode sheet 1, so that the energy density of the electrode assembly can be guaranteed. For example, the two ends of the negative active material region 211 along the direction K are respectively the first end 23 and the second end 24, and the two ends of the positive active material region 111 along the direction K are respectively the third end 13 and the fourth end 14, wherein the first end 23 of the negative active material region 211 and the third end 13 of the positive 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 active material region 211 exceeds the third end 13 of the positive active material region 111 along the direction K, the second end 24 of the negative active material region 211 and the fourth end 14 of the positive 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 active material region 211 exceeds the fourth end 14 of the positive active material region 111 along the direction K.

[0128] The dimensions of the two ends of the negative electrode active material region 211 along the winding axis K that extend beyond the corresponding ends of the positive electrode active material region 111 may be the same or different. For example, the excess dimension ranges from 0.2 mm to 5 mm.

[0129] like Fig.10 As shown, Figure 8 Schematic diagram of the cross-sectional structure in the BB direction, combined with Figure 8 , the barrier layer 4 is attached to the surface of the positive electrode active material region 111 , that is, the surface of the positive electrode active material layer.

[0130] In order to block lithium ions and save costs, the barrier layer 4 includes a fifth end 42 and a sixth end 43 along a direction perpendicular to the bending direction (i.e., direction K), and the fifth end 42 of the barrier layer 4 exceeds the positive active material layer of the positive electrode plate 1 and / or the sixth end 43 of the barrier layer 4 exceeds the positive active material layer, that is, the fifth end 42 of the barrier layer 4 exceeds the third end 13 of the positive active material area 111 along direction K, and / or, the sixth end 43 of the barrier layer 4 exceeds the fourth end 14 of the positive active material area 111 along direction K, for example, the size range of the excess is 0.2 mm to 5 mm. In this way, more lithium ions can be blocked from passing through and the occurrence of lithium precipitation can be reduced.

[0131] In another embodiment of the present application, the fifth end 42 and the sixth end 43 of the barrier layer 4 do not exceed the corresponding ends of the negative active material layer of the negative electrode plate 2, that is, the first end 23 of the negative 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 active material region of the negative electrode plate 2 exceeds the sixth end 43 of the barrier layer 4. In this way, the portion of the negative electrode plate 2 that exceeds the barrier layer 4 can embed lithium ions, and the energy density of the electrode assembly can be guaranteed.

[0132] The above embodiments only generally describe the positional relationship between the barrier layer and the positive electrode sheet and the negative electrode sheet, as well as the structural characteristics of the barrier layer. In order to more clearly understand the positional relationship between the barrier layer and the positive electrode sheet and the negative electrode sheet, as well as the structure of the barrier layer, several electrode assemblies with a winding structure are described in detail below.

[0133] like Fig.11 , which is a schematic structural diagram of a cross section of a flat electrode assembly perpendicular to the winding axis according to another embodiment of the present application, wherein the electrode assembly comprises a negative electrode sheet 91, a positive electrode sheet 92, a separator 93, a first barrier layer 94, a second barrier layer 95 and a third barrier layer 96, wherein the separator 93 is located between the negative electrode sheet 91 and the positive electrode sheet 92, and the separator 93 is two sheets. Fig.11 The cross-sectional view of the electrode assembly is indicated by two dotted lines, where the negative electrode sheet 91, the positive electrode sheet 92 and the separator 93 are stacked and wound around the winding axis into a flat body shape.

[0134] The relevant technical features of the negative electrode sheet 91, the positive electrode sheet 92 and the isolation film 93 of this embodiment can be referred to the aforementioned Figure 1-10 The description of the corresponding embodiments will not be repeated here.

[0135] In this embodiment, the winding structure of the electrode assembly includes a straight area 9A and a first bending area 9B1 and a second bending area 9B2 located on both sides of the straight area 9A, wherein the straight area 9A and the first bending area 9B1 and the second bending area 9B2 are respectively divided by straight dotted lines.

[0136] The electrode assembly includes negative electrode sheets 91 and positive electrode sheets 92 in the first bending zone 9B1 and the second bending zone 9B2, which are alternately stacked in sequence, and a separation film 93 is provided between adjacent negative electrode sheets 91 and positive electrode sheets 92, wherein the innermost sheets in the first bending zone 9B1 and the second bending zone 9B2 are both negative electrode sheets 91, and the inner surface of at least the innermost positive electrode sheet 92 in the first bending zone 9B1 and the second bending zone 9B2 is provided with (for example, attached) a barrier layer, for example, the inner surface of each layer of positive electrode sheet 92 in the first bending zone 9B1 and the second bending zone 9B2 is provided with (for example, attached) a barrier layer. In this embodiment, the inner surface of the positive electrode sheet 92 refers to the surface of the positive electrode sheet 92 facing the winding axis, or the surface facing the inside of the winding structure.

[0137] For example, the first bending zone 9B1 has multiple layers of pole pieces, for example, three layers of pole pieces, the innermost layer (also referred to as the first layer) and the outermost layer (also referred to as the third layer) of the first bending zone 9B1 are both negative pole pieces 91, and the pole piece between the innermost pole piece and the outermost pole piece (also referred to as the second layer pole piece) is a positive pole piece 92, which is the innermost positive pole piece of the first bending zone 9B1, and the first barrier layer 94 is attached to the inner surface of the positive pole piece 92 of the first bending zone 9B1.

[0138] The second bending zone 9B2 has multiple layers of pole sheets, for example, five layers of pole sheets. Along the winding structure from the inside to the outside, the negative pole sheets 91 and the positive pole sheets 92 of the second bending zone 9B2 are alternately stacked in sequence. The innermost pole sheet of the second bending zone 9B2 is the negative pole sheet 91, and a barrier layer is attached to the inner surface of each layer of the positive pole sheet 92 of the second bending zone 9B2.

[0139] For example, along the direction from the inside to the outside of the winding structure, the second bending area 9B2 includes the first, second, third, fourth and fifth layers of pole pieces in sequence, the first, third and fifth layers of pole pieces are negative pole pieces 91, the second and fourth layers of pole pieces are positive pole pieces 92, and the inner surface of each layer of positive pole piece 92 of the second bending area 9B2 is attached with a barrier layer. For example, the second barrier layer 95 is attached to the inner surface of the second layer of pole piece (which is the positive pole piece 92) of the second bending area 9B2. The third barrier layer 96 is attached to the inner surface of the fourth layer of pole piece (which is the positive pole piece 92) of the second bending area 9B2.

[0140] In this embodiment, the two ends of the first barrier layer 94, the second barrier layer 95 and the third barrier layer 96 along the bending direction (i.e., along the winding direction) are respectively located at the junction of the bending area and the straight area. For example, the two ends of the first barrier layer 94 along the winding direction are respectively located at the junction of the first bending area 9B1 and the straight area 9A, and the two ends of the second barrier layer 95 and the third barrier layer 96 along the winding direction are respectively located at the junction of the second bending area 9B2 and the straight area 9A.

[0141] In this embodiment, the functions, structures, and distribution of the first barrier layer 94, the second barrier layer 95, and the third barrier layer 96 can all be referred to in the aforementioned Figure 1-10 The relevant contents of the barrier layer described in the embodiment will not be repeated here.

[0142] like Fig.12 As shown, it is a schematic structural diagram of a cross-section of another flat electrode assembly perpendicular to the winding axis according to another embodiment of the present application, wherein the electrode assembly includes a negative electrode sheet 1001, a positive electrode sheet 1002, an isolation film 1003, a first barrier layer 1004, a second barrier layer 1005 and a third barrier layer 1006, wherein the isolation film 1003 is located between the negative electrode sheet 1001 and the positive electrode sheet 1002, and the negative electrode sheet 1001, the positive electrode sheet 1002 and the isolation film 1003 are superimposed and wound around the winding axis into a flat body-shaped winding structure.

[0143] The relevant technical features of the negative electrode sheet 1001, the positive electrode sheet 1002 and the isolation film 1003 of this embodiment can be referred to the aforementioned Figure 1-10 The description of the corresponding embodiments will not be repeated here.

[0144] In this embodiment, the winding structure of the electrode assembly includes a straight region 10A and a first bending region 10B1 and a second bending region 10B2 located on both sides of the straight region 10A.

[0145] The electrode assembly of this embodiment is Fig.11 The electrode assemblies described in the corresponding embodiments are basically similar, and the differences therebetween may be as follows.

[0146] At least the outer surface of the innermost positive electrode sheet 1002 of the first bending area 10B1 and the second bending area 10B2 is provided with (e.g., attached with) a barrier layer. For example, the outer surface of each layer of positive electrode sheet 1002 of the first bending area 10B1 and the second bending area 10B2 is provided with (e.g., attached with) a barrier layer. In this embodiment, the outer surface of the positive electrode sheet 1002 refers to the surface of the positive electrode sheet 1002 that is opposite to the winding axis, or the surface that is opposite to the inside of the winding structure.

[0147] For example, the first barrier layer 1004 is attached to the outer surface of the positive electrode tab 1002 in the first bending region 10B1 .

[0148] For example, the second barrier layer 1005 is attached to the outer surface of the second electrode sheet (which is the positive electrode sheet 1002) of the second bending region 10B2. The third barrier layer 1006 is attached to the outer surface of the fourth electrode sheet (which is the positive electrode sheet 1002) of the second bending region 10B2.

[0149] In this embodiment, the two ends of the first barrier layer 1004 along the winding direction are respectively located at the junction of the first bending area 10B1 and the straight area 10A, and the two ends of the second barrier layer 1005 and the third barrier layer 1006 along the winding direction are respectively located at the junction of the second bending area 10B2 and the straight area 10A.

[0150] In this embodiment, the functions, structures, and distribution of the first barrier layer 1004, the second barrier layer 1005, and the third barrier layer 1006 can also be referred to in the aforementioned Figure 1-10 The relevant contents of the barrier layer described in the embodiment will not be repeated here.

[0151] like Fig.13 As shown, it is a schematic structural diagram of a cross-section of another flat electrode assembly perpendicular to the winding axis according to another embodiment of the present application, wherein the electrode assembly includes a negative electrode sheet 1101, a positive electrode sheet 1102, an isolation film 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, wherein the isolation film 1103 is located between the negative electrode sheet 1101 and the positive electrode sheet 1102, and the negative electrode sheet 1101, the positive electrode sheet 1102 and the isolation film 1103 are superimposed and wound around the winding axis into a flat body-shaped winding structure.

[0152] The relevant technical features of the negative electrode sheet 1101, the positive electrode sheet 1102 and the isolation film 1103 of this embodiment can be referred to the aforementioned Figure 1-10 The description of the corresponding embodiments will not be repeated here.

[0153] In this embodiment, the winding structure of the electrode assembly includes a straight region 11A and a first bending region 11B1 and a second bending region 11B2 located on both sides of the straight region 11A.

[0154] The electrode assembly of this embodiment is Fig.11 The electrode assemblies described in the corresponding embodiments are basically similar, and the differences therebetween may be as follows.

[0155] The inner surface of at least the innermost negative electrode sheet 1101 of the first bending area 11B1 and the second bending area 11B2 is provided with (e.g., attached with) a barrier layer, for example, the inner surface of each layer of negative electrode sheet 1101 of the first bending area 11B1 and the second bending area 11B2 is provided with a barrier layer. In this embodiment, the inner surface of the negative electrode sheet 1101 refers to the surface of the negative electrode sheet 1101 facing the winding axis, or the surface facing the inside of the winding structure.

[0156] For example, the first barrier layer 1104 is attached to the inner surface of the innermost electrode sheet (which is the negative electrode sheet 1101 ) of the first bending region 11B1 , and the second barrier layer 1105 is attached to the inner surface of the outermost electrode sheet (which is the negative electrode sheet 1101 ).

[0157] For example, the third barrier layer 1106 is attached to the inner surface of the first electrode sheet (which is the negative electrode sheet 1101) of the second bending region 11B2. The fourth barrier layer 1107 is attached to the inner surface of the third electrode sheet (which is the negative electrode sheet 1101) of the second bending region 11B2. The fifth barrier layer 1108 is attached to the inner surface of the fifth electrode sheet (which is the negative electrode sheet 1101) of the second bending region 11B2.

[0158] In this embodiment, the two ends of the first barrier layer 1104 and the second barrier layer 1105 along the winding direction are respectively located at the junction of the first bending area 11B1 and the straight area 11A, and the two ends of the third barrier layer 1106, the fourth barrier layer 1107 and the fifth barrier layer 1108 along the winding direction are respectively located at the junction of the second bending area 11B2 and the straight area 11A.

[0159] In this embodiment, the functions, structures, distribution methods, etc. 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 can all be referred to in the aforementioned Figure 1-10 The relevant contents of the barrier layer described in the embodiment will not be repeated here.

[0160] like Fig.14 As shown, it is a schematic structural diagram of a cross-section of another flat electrode assembly perpendicular to the winding axis according to another embodiment of the present application, wherein the electrode assembly includes a negative electrode sheet 1201, a positive electrode sheet 1202, an isolation film 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, wherein the isolation film 1203 is located between the negative electrode sheet 1201 and the positive electrode sheet 1202, and the negative electrode sheet 1201, the positive electrode sheet 1202 and the isolation film 1203 are superimposed and wound around the winding axis into a flat body-shaped winding structure.

[0161] The relevant technical features of the negative electrode sheet 1201, the positive electrode sheet 1202 and the isolation film 1203 of this embodiment can be referred to the aforementioned Figure 1-10 The description of the corresponding embodiments will not be repeated here.

[0162] In this embodiment, the winding structure of the electrode assembly includes a straight region 12A and a first bending region 12B1 and a second bending region 12B2 located on both sides of the straight region 12A.

[0163] The electrode assembly of this embodiment is Fig.11 The electrode assemblies described in the corresponding embodiments are basically similar, and the differences therebetween may be as follows.

[0164] The outer surface of at least the innermost negative electrode sheet 1201 of the first bending area 12B1 and the second bending area 12B2 is provided with (e.g., attached with) a barrier layer, for example, the outer surface of each layer of negative electrode sheet 1201 of the first bending area 12B1 and the second bending area 12B2 is provided with a barrier layer. In this embodiment, the outer surface of the negative electrode sheet 1201 refers to the surface of the negative electrode sheet 1201 that is away from the winding axis, or the surface that is away from the inside of the winding structure.

[0165] For example, the first barrier layer 1204 is attached to the outer surface of the innermost electrode sheet (which is the negative electrode sheet 1201) of the first bending region 12B1, and the second barrier layer 1205 is attached to the outer surface of the outermost electrode sheet (which is the negative electrode sheet 1201).

[0166] For example, the third barrier layer 1206 is attached to the outer surface of the first electrode sheet (which is the negative electrode sheet 1201) of the second bending region 12B2. The fourth barrier layer 1207 is attached to the outer surface of the third electrode sheet (which is the negative electrode sheet 1201) of the second bending region 12B2. The fifth barrier layer 1208 is attached to the outer surface of the fifth electrode sheet (which is the negative electrode sheet 1201) of the second bending region 12B2.

[0167] In this embodiment, the two ends of the first barrier layer 1204 and the second barrier layer 1205 along the winding direction are respectively located at the junction of the first bending area 12B1 and the straight area 12A, and the two 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 junction of the second bending area 12B2 and the straight area 12A.

[0168] In this embodiment, the functions, structures, distribution methods, etc. 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 can all be referred to in the aforementioned Figure 1-10 The relevant contents of the barrier layer described in the embodiment will not be repeated here.

[0169] like Fig.15 As shown, it is a schematic structural diagram of a cross-section of another flat electrode assembly perpendicular to the winding axis according to another embodiment of the present application, wherein the electrode assembly includes a negative electrode sheet 1301, a positive electrode sheet 1302, an isolation film 1303 and a plurality of barrier layers 1304, wherein the isolation film 1303 is located between the negative electrode sheet 1301 and the positive electrode sheet 1302, and the negative electrode sheet 1301, the positive electrode sheet 1302 and the isolation film 1303 are superimposed and wound around the winding axis into a flat winding structure.

[0170] The relevant technical features of the negative electrode sheet 1301, the positive electrode sheet 1302 and the isolation film 1303 of this embodiment can be referred to the aforementioned Figure 1-10 The description of the corresponding embodiments will not be repeated here.

[0171] In this embodiment, the winding structure of the electrode assembly includes a straight region 13A and a first bending region 13B1 and a second bending region 13B2 located on both sides of the straight region 13A.

[0172] The electrode assembly of this embodiment is Fig.11 The electrode assemblies described in the corresponding embodiments are basically similar, and the differences therebetween may be as follows.

[0173] At least the inner surface of the innermost isolation film 1303 of the first bending zone 13B1 and the second bending zone 13B2 is attached with a barrier layer 1304. For example, the inner surface of each isolation film 1303 of the first bending zone 13B1 and the second bending zone 13B2 is attached with a barrier layer 1304. In this embodiment, the inner surface of the isolation film 1303 refers to the surface of the isolation film 1303 facing the winding axis, or the surface facing the inside of the winding structure.

[0174] In this embodiment, the two ends of each barrier layer 1304 in the first bending zone 13B1 along the winding direction are respectively located at the junction of the first bending zone 13B1 and the straight zone 13A, and the two ends of each barrier layer 1304 in the second bending zone 13B2 along the winding direction are respectively located at the junction of the second bending zone 12B2 and the straight zone 12A.

[0175] In this embodiment, the function, structure, distribution and other related contents of each barrier layer 1304 can refer to the aforementioned Figure 1-10 The relevant contents of the barrier layer described in the embodiment will not be repeated here.

[0176] like Fig.16 As shown, it is a schematic structural diagram of a cross-section of another flat electrode assembly perpendicular to the winding axis according to another embodiment of the present application, wherein the electrode assembly includes a negative electrode sheet 1401, a positive electrode sheet 1402, an isolation film 1403 and a plurality of barrier layers 1404, wherein the isolation film 1403 is located between the negative electrode sheet 1401 and the positive electrode sheet 1402, and the negative electrode sheet 1401, the positive electrode sheet 1402 and the isolation film 1403 are superimposed and wound around the winding axis into a flat winding structure.

[0177] The relevant technical features of the negative electrode sheet 1401, the positive electrode sheet 1402 and the isolation film 1403 of this embodiment can be referred to the aforementioned Figure 1-10 The description of the corresponding embodiments will not be repeated here.

[0178] In this embodiment, the winding structure of the electrode assembly includes a straight region 14A and a first bending region 14B1 and a second bending region 14B2 located on both sides of the straight region 14A.

[0179] The electrode assembly of this embodiment is Fig.11 The electrode assemblies described in the corresponding embodiments are basically similar, and the differences therebetween may be as follows.

[0180] The outer surface of at least the innermost isolation film 1403 of the first bending zone 14B1 and the second bending zone 14B2 is attached with a barrier layer 1404. For example, the outer surface of each isolation film 1403 of the first bending zone 14B1 and the second bending zone 14B2 is attached with a barrier layer 1404. In this embodiment, the outer surface of the isolation film 1403 refers to the surface of the isolation film 1403 that is away from the winding axis, or the surface that is away from the inside of the winding structure.

[0181] In this embodiment, both ends of each barrier layer 1404 in the first bending zone 14B1 along the winding direction are respectively located at the junction of the first bending zone 14B1 and the straight zone 14A, and both ends of each barrier layer 1404 in the second bending zone 14B2 along the winding direction are respectively located at the junction of the second bending zone 12B2 and the straight zone 12A.

[0182] In this embodiment, the function, structure, distribution and other related contents of each barrier layer 1404 can refer to the aforementioned Figure 1-10 The relevant contents of the barrier layer described in the embodiment will not be repeated here.

[0183] like Fig.17 As shown, it is a schematic structural diagram of a cross-section of another flat electrode assembly perpendicular to the winding axis according to another embodiment of the present application, wherein the electrode assembly includes a negative electrode sheet 1501, a positive electrode sheet 1502, an isolation film 1503 and a plurality of barrier layers 1504, wherein the isolation film 1503 is located between the negative electrode sheet 1501 and the positive electrode sheet 1502, and the negative electrode sheet 1501, the positive electrode sheet 1502 and the isolation film 1503 are superimposed and wound around the winding axis into a flat winding structure.

[0184] The relevant technical features of the negative electrode sheet 1501, the positive electrode sheet 1502 and the isolation film 1503 of this embodiment can be referred to the aforementioned Figure 1-10 The description of the corresponding embodiments will not be repeated here.

[0185] In this embodiment, the winding structure of the electrode assembly includes a straight region 15A and a first bending region 15B1 and a second bending region 15B2 located on both sides of the straight region 15A.

[0186] The electrode assembly includes negative electrode sheets 1501 and positive electrode sheets 1502 which are alternately stacked in sequence in the first bending zone 15B1 and the second bending zone 15B2, and an isolation film 1503 is provided between any adjacent negative electrode sheets 1501 and positive electrode sheets 1502 in the first bending zone 15B1 and the second bending zone 15B2, wherein the innermost electrode sheets in the first bending zone 15B1 and the second bending zone 15B2 are both negative electrode sheets 1501, and the inner and outer surfaces of at least the innermost positive electrode sheets 1502 in the first bending zone 15B1 and the second bending zone 15B2 are both provided with a barrier layer 1504, for example, the inner and outer surfaces of each layer of positive electrode sheets 1502 in the first bending zone 15B1 and the second bending zone 15B2 are both provided with a barrier layer 1504. In this embodiment, the inner surface of the positive electrode sheet 1502 refers to the surface of the positive electrode sheet 1502 facing the winding axis, or the surface facing the inside of the winding structure, and the outer surface of the positive electrode sheet 1502 refers to the surface of the positive electrode sheet 1502 facing away from the winding axis, or the surface facing away from the inside of the winding structure.

[0187] For example, the first bending zone 15B1 has multiple layers of pole pieces, such as three layers of pole pieces, the innermost layer (also referred to as the first layer) and the outermost layer (also referred to as the third layer) of the first bending zone 15B1 are both negative pole pieces 1501, the pole piece between the innermost pole piece and the outermost pole piece of the first bending zone 15B1 (also referred to as the second layer pole piece) is a positive pole piece 1502, and the inner and outer surfaces of the positive pole piece 1502 of the first bending zone 15B1 are both provided with (for example, attached with) a barrier layer 1504.

[0188] The second bending zone 15B2 has multiple layers of pole sheets, for example, five layers of pole sheets. Along the direction from the inside to the outside of the winding structure, the negative pole sheets 1501 and the positive pole sheets 1502 of the second bending zone 15B2 are alternately stacked in sequence. The innermost pole sheet of the second bending zone 15B2 is the negative pole sheet 1501, and the inner and outer surfaces of each layer of positive pole sheets 1502 of the second bending zone 15B2 are provided with (for example, attached) a barrier layer 1504.

[0189] For example, along the direction from the inside to the outside of the winding structure, the second bending zone 15B2 includes the first, second, third, fourth and fifth layers of pole sheets in sequence, the first, third and fifth layers of pole sheets are negative pole sheets 1501, the second and fourth layers of pole sheets are positive pole sheets 1502, and the inner and outer surfaces of the second and fourth layers of pole sheets in the second bending zone 15B2 are both provided with a barrier layer 1504.

[0190] In this embodiment, the two ends of each barrier layer 1504 along the bending direction (i.e., along the winding direction) are respectively located at the junction of the bending zone and the straight zone. For example, the two ends of each barrier layer 1504 in the first bending zone 15B1 along the winding direction are respectively located at the junction of the first bending zone 15B1 and the straight zone 15A, and the two ends of each barrier layer 1504 in the second bending zone 15B2 along the winding direction are respectively located at the junction of the second bending zone 15B2 and the straight zone 15A.

[0191] In this embodiment, the function, structure, distribution and other related contents of each barrier layer 1504 can refer to the aforementioned Figure 1-10 The relevant contents of the barrier layer described in the embodiment will not be repeated here.

[0192] like Fig.18 As shown, it is a schematic structural diagram of a cross-section of a flat electrode assembly perpendicular to the winding axis in another embodiment of the present application, wherein the electrode assembly includes a negative electrode sheet 1601, a positive electrode sheet 1602, an isolation film 1603, a first barrier layer 1604, a second barrier layer 1605 and a third barrier layer 1606, wherein the isolation film 1603 is located between the negative electrode sheet 1601 and the positive electrode sheet 1602, and the negative electrode sheet 1601, the positive electrode sheet 1602 and the isolation film 1603 are superimposed and wound around the winding axis into a flat body-shaped winding structure.

[0193] The relevant technical features of the negative electrode sheet 1601, the positive electrode sheet 1602 and the isolation film 1603 of this embodiment can be referred to the aforementioned Figure 1-10 The description of the corresponding embodiments will not be repeated here.

[0194] In this embodiment, the winding structure of the electrode assembly includes a first straight area 16A1, a second straight area 16A2, a first bending area 16B1 and a second bending area 16B2. The first straight area 16A1 and the second straight area 16A2 are arranged opposite to each other, and the first bending area 16B1 and the second bending area 16B2 are arranged opposite to each other. The two ends of the first bending area 16B1 are respectively connected to the same side end of the first straight area 16A1 and the second straight area 16A2, and the two ends of the second bending area 16B2 are respectively connected to the other same side end of the first straight area 16A1 and the second straight area 16A2.

[0195] The electrode assembly includes negative electrode sheets 1601 and positive electrode sheets 1602 in the first bending area 16B1 and the second bending area 16B2, which are alternately stacked in sequence, and a separator 1603 is provided between adjacent negative electrode sheets 1601 and positive electrode sheets 1602, wherein the innermost electrode sheets in the first bending area 16B1 and the second bending area 16B2 are both negative electrode sheets 1601, and the inner surface of at least the innermost positive electrode sheet 1602 in the first bending area 16B1 and the second bending area 16B2 is provided with (for example, attached) a barrier layer, for example, the inner surface of each layer of positive electrode sheet 1602 in the first bending area 16B1 and the second bending area 16B2 is provided with (for example, attached) a barrier layer. In this embodiment, the inner surface of the positive electrode sheet 1602 refers to the surface of the positive electrode sheet 1602 facing the winding axis, or the surface facing the inside of the winding structure.

[0196] For example, the first bending zone 16B1 has multiple layers of pole pieces, such as three layers of pole pieces, the innermost layer (also called the first layer) and the outermost layer (also called the third layer) of the first bending zone 16B1 are both negative pole pieces 1601, the pole piece between the innermost pole piece and the outermost pole piece (also called the second layer pole piece) is the positive pole piece 1602, and the first barrier layer 1604 is attached to the inner surface of the positive pole piece 1602 of the first bending zone 16B1.

[0197] For example, the second bending zone 16B2 has multiple layers of pole sheets, for example, five layers of pole sheets. Along the winding structure from the inside to the outside, the negative pole sheets 1601 and the positive pole sheets 1602 of the second bending zone 16B2 are alternately stacked in sequence. The innermost pole sheet of the second bending zone 16B2 is the negative pole sheet 1601, and a barrier layer is attached to the inner surface of each layer of the positive pole sheet 1602 of the second bending zone 16B2.

[0198] For example, along the direction from the inside to the outside of the winding structure, the second bending region 16B2 includes the first, second, third, fourth and fifth layers of pole pieces in sequence, the first, third and fifth layers of pole pieces are negative pole pieces 1601, the second and fourth layers of pole pieces are positive pole pieces 1602, and the second barrier layer 1605 is attached to the inner surface of the positive pole piece 1602 in the innermost adjacent negative pole piece 1601 and positive pole piece 1602 of the second bending region 16B2, that is, the second barrier layer 1605 is attached to the inner surface of the second layer of pole piece (which is the positive pole piece 1602) of the second bending region 16B2. The third barrier layer 1606 is attached to the inner surface of the fourth layer of pole piece (which is the positive pole piece 1602) of the second bending region 16B2.

[0199] In this embodiment, the first barrier layer 1604 includes a first end and a second end along the bending direction (i.e., along the winding direction), the first end of the first barrier layer 1604 is located in the first bending area 16B1, and the second end of the first barrier layer 1604 is located in the first straight area 16A1. The second barrier layer 1605 includes a first end and a second end along the bending direction (i.e., along the winding direction), the first end of the second barrier layer 1605 is located in the second bending area 16B2, and the second end of the second barrier layer 1605 is located in the second straight area 16A2. The third barrier layer 1606 includes a first end and a second end along the bending direction (i.e., along the winding direction), the first end of the third barrier layer 1606 is located in the second bending area 16B2, and the second end of the third barrier layer 1606 is located in the second straight area 16A2. In another embodiment of the present application, the first end of the third barrier layer 1606 is located in the second bending area 16B2, and the second end of the third barrier layer 1606 can be located in the first straight area 16A1.

[0200] In this embodiment, the functions, structures, and distribution of the first barrier layer 1604, the second barrier layer 1605, and the third barrier layer 1606 can all be referred to in the aforementioned Figure 1-10 The relevant contents of the barrier layer described in the embodiment will not be repeated here.

[0201] like Fig.19 As shown, it is a schematic structural diagram of a cross-section of a flat electrode assembly perpendicular to the winding axis in another embodiment of the present application, wherein the electrode assembly includes a negative electrode sheet 1701, a positive electrode sheet 1702, an isolation film 1703, a first barrier layer 1704, a second barrier layer 1705 and a third barrier layer 1706, wherein the isolation film 1703 is located between the negative electrode sheet 1701 and the positive electrode sheet 1702, and the negative electrode sheet 1701, the positive electrode sheet 1702 and the isolation film 1703 are superimposed and wound around the winding axis into a flat body-shaped winding structure.

[0202] The relevant technical features of the negative electrode sheet 1701, the positive electrode sheet 1702 and the isolation film 1703 of this embodiment can be referred to the aforementioned Figure 1-10 The description of the corresponding embodiments will not be repeated here.

[0203] In this embodiment, the winding structure of the electrode assembly includes a first straight area 17A1, a second straight area 17A2, a first bending area 17B1 and a second bending area 17B2. The first straight area 17A1 and the second straight area 17A2 are arranged opposite to each other, and the first bending area 17B1 and the second bending area 17B2 are arranged opposite to each other. The two ends of the first bending area 17B1 are respectively connected to the same side end of the first straight area 17A1 and the second straight area 17A2, and the two ends of the second bending area 17B2 are respectively connected to the other same side end of the first straight area 17A1 and the second straight area 17A2.

[0204] The electrode assembly includes negative electrode sheets 1701 and positive electrode sheets 1702 which are alternately stacked in sequence in the first bending zone 17B1 and the second bending zone 17B2, and a separator 1703 is provided between adjacent negative electrode sheets 1701 and positive electrode sheets 1702, wherein the innermost sheets of the first bending zone 17B1 and the second bending zone 17B2 are both negative electrode sheets 1701, and the inner surface of at least the innermost positive electrode sheet 1702 of the first bending zone 17B1 and the second bending zone 17B2 is provided with (for example, attached) a barrier layer, for example, the inner surface of each layer of positive electrode sheet 1702 of the first bending zone 17B1 and the second bending zone 17B2 is provided with (for example, attached) a barrier layer. In this embodiment, the inner surface of the positive electrode sheet 1702 refers to the surface of the positive electrode sheet 1702 facing the winding axis, or the surface facing the inside of the winding structure.

[0205] For example, the first bending zone 17B1 has multiple layers of pole pieces, such as three layers of pole pieces, the innermost layer (also called the first layer) and the outermost layer (also called the third layer) of the first bending zone 17B1 are both negative pole pieces 1701, the pole piece between the innermost pole piece and the outermost pole piece (also called the second layer pole piece) is the positive pole piece 1702, and the first barrier layer 1704 is attached to the inner surface of the positive pole piece 1702 of the first bending zone 17B1.

[0206] The second bending zone 17B2 has multiple layers of pole sheets, for example, five layers of pole sheets. Along the direction from the inside to the outside of the winding structure, the negative pole sheets 1701 and the positive pole sheets 1702 of the second bending zone 17B2 are alternately stacked in sequence. The innermost pole sheet of the second bending zone 17B2 is the negative pole sheet 1701, and a barrier layer is attached to the inner surface of each layer of the positive pole sheet 1702 of the second bending zone 17B2.

[0207] For example, along the direction from the inside to the outside of the winding structure, the second bending area 17B2 includes the first, second, third, fourth and fifth layers of pole pieces in sequence, the first, third and fifth layers of pole pieces are negative pole pieces 1701, the second and fourth layers of pole pieces are positive pole pieces 1702, and the second barrier layer 1705 is attached to the inner surface of the positive pole piece 1702 in the innermost adjacent negative pole piece 1701 and positive pole piece 1702 of the second bending area 17B2, that is, the second barrier layer 1705 is attached to the inner surface of the second layer of pole piece (which is the positive pole piece 1702) of the second bending area 17B2. The third barrier layer 1706 is attached to the inner surface of the fourth layer of pole piece (which is the positive pole piece 1702) of the second bending area 17B2.

[0208] In this embodiment, the first barrier layer 1704 includes a first end and a second end along the bending direction (i.e., along the winding direction), and the first end and the second end of the first barrier layer 1704 are both located in the first bending area 17B1. The second barrier layer 1705 includes a first end and a second end along the bending direction (i.e., along the winding direction), and the first end of the second barrier layer 1705 is located at the junction of the second bending area 17B2 and the first straight area 17A1, and the second end of the second barrier layer 1705 is located at the junction of the second bending area 17B2 and the second straight area 17A2. The third barrier layer 1706 includes a first end and a second end along the bending direction (i.e., along the winding direction), and the first end and the second end of the third barrier layer 1706 are both located in the second bending area 17B2.

[0209] In this embodiment, in the second bending zone 17B2, along the direction perpendicular to the winding axis and from the inside to the outside of the electrode assembly, the curvature of each layer of the electrode sheet decreases successively, that is, the bending degree decreases successively. Then, along the direction perpendicular to the winding axis and from the inside to the outside of the electrode assembly, the circumferential angle covered by each barrier layer in the second bending zone 17B2 along the winding direction can be reduced successively. For example, the circumferential angle covered by the third barrier layer 1706 in the second bending zone 17B2 along the winding direction is smaller than the circumferential angle covered by the second barrier layer 1705 in the second bending zone 17B2. For example, the circumferential angle covered by the third barrier layer 1706 in the second bending zone 17B2 along the winding direction is 90°, and the circumferential angle covered by the second barrier layer 1705 in the second bending zone 17B2 along the winding direction is 180°.

[0210] In this embodiment, the functions, structures, and distribution of the first barrier layer 1704, the second barrier layer 1705, and the third barrier layer 1706 can all be referred to in the aforementioned Figure 1-10 The relevant contents of the barrier layer described in the embodiment will not be repeated here.

[0211] like Fig. 20 , which is a schematic diagram of the structure of a battery cell according to another embodiment of the present application. The battery cell includes a shell 181 and one or more electrode assemblies 182 accommodated in the shell 181. The shell 181 includes a housing 1811 and a cover plate 1812. The housing 1811 has a receiving cavity, and the housing 1811 has an opening, that is, the plane does not have a housing wall so that the inside and outside of the housing 1811 are connected, so that the electrode assembly 182 can be accommodated in the receiving cavity of the housing 1811. The cover plate 1812 and the housing 1811 are combined at the opening of the housing 1811 to form a hollow cavity. After the electrode assembly 182 is accommodated in the shell 181, the shell 181 is filled with electrolyte and sealed.

[0212] The shell 1811 is determined according to the shape of one or more electrode assemblies 182 after being combined. For example, the shell 1811 may be a hollow cuboid, a hollow cube, or a hollow cylinder. For example, when the shell 1811 is a hollow cuboid or a cube, one of the planes of the shell 1811 is an open surface, that is, the plane does not have a shell wall so that the inside and outside of the shell 1811 are connected; when the shell 1811 is a hollow cylinder, one of the circular side surfaces of the shell 1811 is an open surface, that is, the circular side surface does not have a shell wall so that the inside and outside of the shell 1811 are connected.

[0213] In another embodiment of the present application, the housing 1811 may be made of a conductive metal material or plastic. Optionally, the housing 1811 is made of aluminum or an aluminum alloy.

[0214] The structure of the electrode assembly 182 can refer to the aforementioned Figure 1-19 The relevant contents of the electrode assembly described in the embodiment will not be repeated here.

[0215] like Fig.21 FIG. 1 is a schematic diagram of a battery module structure of another embodiment of the present application. The battery module 19 includes a plurality of interconnected battery cells 191, wherein the plurality of battery cells 191 may be connected in series, in parallel, or in mixed connection. Mixed connection means that the connection includes both series connection and parallel connection. The structure of the battery cell 191 may refer to Fig. 20 The battery cells described in the corresponding embodiments are not described in detail here.

[0216] like Fig. 22 As shown, it is a structural schematic diagram of a battery of another embodiment of the present application, the battery includes a plurality of battery modules 19 and a box body, the box body includes a lower box body 20 and an upper box body 30, the plurality of battery modules 19 can be connected in series, in parallel or mixed, the lower box body 20 has a accommodating cavity, and the lower box body 20 has an opening, so that the connected plurality of battery modules 19 can be accommodated in the accommodating cavity of the lower box body 20, the upper box body 30 and the lower box body 20 are combined at the opening of the lower box body 20 to form a hollow cavity, and the upper box body 30 and the lower box body 20 are sealed after being combined.

[0217] In another embodiment of the present application, the battery can independently supply power to an electrical device, and the battery can be referred to as a battery pack, for example, used to supply power to an automobile.

[0218] In another embodiment of the present application, according to the power demand of the power-consuming device, multiple batteries are connected to form a battery pack to supply power to the power-consuming device. In another embodiment of the present application, the battery pack can also be contained in a box and packaged.

[0219] To simplify the description, the following embodiments are described by taking the electrical device including a battery as an example.

[0220] In one embodiment of the present application, there is also provided an electric device, for example, the electric device may be a car, for example, a new energy car, the electric device includes the battery described in the above embodiment, wherein the battery used in the electric device may be as follows Fig. 22 The batteries described in the corresponding embodiments are not described in detail here.

[0221] For example, Fig.23 As shown, it is a schematic diagram of the structure of an electric device of another embodiment of the present application. The electric device can be a car. The car can be a fuel car, a gas car or a new energy car. The new energy car can be a pure electric car, a hybrid car or an extended-range car, etc. The car includes a battery 2101, a controller 2102 and a motor 2103. The battery 2101 is used to supply power to the controller 2102 and the motor 2103 as the operating power supply and driving power supply of the car. For example, the battery 2101 is used for the working power demand during the start, navigation and operation of the car. 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 and uses the power of the battery 2101 as the driving power supply of the car, replacing or partially replacing fuel or natural gas to provide driving power for the car.

[0222] like Fig.24 , which is a schematic flow chart 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 contents.

[0223] Step 221, providing a positive electrode sheet, a negative electrode sheet and a barrier layer.

[0224] Step 222, winding or stacking the positive electrode sheet and the negative electrode sheet to form a bending area.

[0225] A barrier layer is provided in the bending region, wherein at least a portion of the barrier layer is located between adjacent positive electrode sheets and negative electrode sheets, and is used to block at least a portion of ions escaped from the positive electrode sheets from being embedded in the bending region of the negative electrode sheets.

[0226] In another embodiment of the present application, a separator is provided for separating adjacent positive electrode sheets and negative electrode sheets, and the separator, the positive electrode sheets and the negative electrode sheets are wound or stacked together.

[0227] In another embodiment of the present application, before the separator, the positive electrode sheet and the negative electrode sheet are wound or stacked together, a barrier layer is placed on one or both surfaces of the positive electrode sheet or the negative electrode sheet. For example, the barrier layer is pasted or coated on one or both surfaces of the positive electrode sheet or the negative electrode sheet.

[0228] The relevant structure of the electrode assembly manufactured by the manufacturing method of this embodiment can refer to the aforementioned Figure 1-19The relevant contents of the electrode assembly described in the corresponding embodiment will not be repeated here.

[0229] like Fig.25 , which is a schematic diagram of the structure of a manufacturing device for an electrode assembly according to another embodiment of the present application, the manufacturing device for the electrode assembly includes: a first providing device 231 , a second providing device 232 , a third providing device 233 and an assembling device 234 .

[0230] The first providing device 231 is used to provide a positive electrode plate.

[0231] The second providing device 232 is used to provide negative electrode sheets.

[0232] The third providing device 233 is used to provide a barrier layer.

[0233] The assembly device 234 is used to wind or stack the positive electrode sheets and the negative electrode sheets to form a bending area.

[0234] There is a barrier layer in the bending area, wherein at least a portion of the barrier layer is located between adjacent positive electrode sheets and negative electrode sheets, and is used to block at least a portion of ions escaped from the positive electrode sheet from being embedded in the bending area of ​​the negative electrode sheet.

[0235] In another embodiment of the present application, the manufacturing equipment of the electrode assembly also includes a fourth providing device 235, which is used to provide an isolation film for separating adjacent positive electrode sheets and negative electrode sheets, and the assembling device 234 is used to form a bending area by winding or stacking the positive electrode sheets, negative electrode sheets and isolation films.

[0236] In another embodiment of the present application, there are two third providing devices 233, and the two third providing devices 233 are used to respectively provide a barrier layer, and to stick or coat the barrier layer on the two surfaces of the positive electrode sheet or the negative electrode sheet.

[0237] The relevant structure of the electrode assembly manufactured by the manufacturing equipment of this embodiment can refer to the aforementioned Figure 1-19 The relevant contents of the electrode assembly described in the corresponding embodiment will not be repeated here.

[0238] In summary, the electrode assembly of the battery cell includes a barrier layer arranged between adjacent positive electrode sheets and negative electrode sheets. During charging, at least a portion of the ions released from the positive electrode active material layer of the positive electrode sheet in the bending zone are blocked by the barrier layer, so that the ions blocked by the barrier layer cannot be embedded in the negative electrode active material layer of the negative electrode sheet adjacent to the positive electrode sheet in the bending zone. When the negative electrode active material of the negative electrode sheet falls off, the occurrence of lithium plating is reduced, the safety risk of the battery cell is improved, and the service life of the battery cell is improved.

[0239] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0240] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, wherein: include: A housing (1811) having a receiving cavity and an opening; A cover plate (1812) for closing the opening of the housing (1811); At least one electrode assembly (182) is accommodated in the accommodation cavity, the electrode assembly (182) comprising a positive electrode sheet (1) and a negative electrode sheet (2), the positive electrode sheet (1) and the negative electrode sheet (2) being wound or stacked to form a bending area (C); The bending region (C) has a barrier layer (4), wherein at least a portion of the barrier layer (4) is located between the adjacent positive electrode sheet (1) and the negative electrode sheet (2), and is used to block at least a portion of ions escaped from the positive electrode sheet (1) from being embedded in the negative electrode sheet (2) of the bending region (C).

2. The battery cell according to claim 1, wherein: The electrode assembly further comprises an isolation film (3) for isolating the adjacent positive electrode sheet (1) and the negative electrode sheet (2); the barrier layer (4) is independently located between the adjacent positive electrode sheet (1) and the negative electrode sheet (2); and / or the barrier layer (4) is attached to one or both surfaces of the positive electrode sheet (1); and / or the barrier layer (4) is attached to one or both surfaces of the negative electrode sheet (2); and / or the barrier layer (4) is attached to one or both surfaces of the isolation film (3).

3. The battery cell according to claim 1, wherein: The electrode assembly further comprises an isolation film (3) for isolating the adjacent positive electrode sheet (1) and the negative electrode sheet (2); the barrier layer (4) is independent of the positive electrode sheet (1) and the isolation film (3) adjacent to the bending zone (C); or the barrier layer (4) is independent of the negative electrode sheet (2) and the isolation film (3) adjacent to the bending zone (C).

4. The battery cell according to claim 2 or 3, wherein: The porosity of the barrier layer (4) is smaller than the porosity of the isolation film (3).

5. The battery cell according to any one of claims 1 to 4, wherein: The electrode assembly comprises a positive electrode sheet (1) and a negative electrode sheet (2), wherein the positive electrode sheet (1) and the negative electrode sheet (2) are compacted and then wound to form a winding structure, wherein the barrier layer (4) is provided between at least the innermost adjacent positive electrode sheet (1) and the negative electrode sheet (2) in the bending area (C).

6. The battery cell according to claim 5, wherein: The innermost pole piece of the bending area (C) is the negative pole piece (2).

7. The battery cell according to any one of claims 1 to 6, wherein: The barrier layers (4) are multiple and discontinuous, and the multiple and discontinuous barrier layers (4) are distributed at intervals along the bending direction, or the multiple and discontinuous barrier layers (4) are distributed at intervals along a direction perpendicular to the bending direction.

8. The battery cell according to any one of claims 1 to 7, wherein: The thickness of the barrier layer (4) is 2-200 microns.

9. The battery cell according to claim 8, wherein: The thickness of the barrier layer (4) is 5-100 microns.

10. The battery cell according to claim 9, wherein: The thickness of the barrier layer (4) is 5-50 microns.

11. The battery cell according to any one of claims 1 to 10, wherein: The barrier layer (4) has at least one through hole, and the through hole is used for some ions to pass through so as to be embedded in the negative electrode plate (2).

12. The battery cell according to claim 11, wherein: The porosity of the barrier layer (4) is 10%-70%.

13. The battery cell according to claim 12, wherein: The porosity of the barrier layer (4) is 20%-60%.

14. The battery cell according to any one of claims 11 to 13, wherein: The thickness of the barrier layer (4) is A micrometers, and the porosity of the barrier layer (4) is B, wherein A and B satisfy the following relationship: 3.5 microns ≤ A / B ≤ 2000 microns.

15. The battery cell according to claim 14, wherein: A and B satisfy the following relationship: 7 microns ≤ A / B ≤ 1000 microns.

16. The battery cell according to any one of claims 1 to 15, wherein: Both ends of the negative electrode active material layer of the negative electrode plate (2) along the direction perpendicular to the bending direction extend beyond the corresponding ends of the positive electrode active material layer of the positive electrode plate (1).

17. The battery cell according to any one of claims 1 to 16, wherein: The barrier layer (4) includes two ends along a direction perpendicular to the bending direction, and one end or both ends of the barrier layer (4) extend beyond the positive electrode active material layer of the positive electrode plate (1).

18. The battery cell according to claim 17, wherein: One or both ends of the barrier layer (4) extend beyond the positive electrode active material layer of the positive electrode plate (1) by a size ranging from 0.2 mm to 5 mm.

19. The battery cell according to any one of claims 1 to 16, wherein: The barrier layer (4) includes two ends along a direction perpendicular to the bending direction, and the negative electrode active material layer of the negative electrode plate (2) extends beyond one or both ends of the barrier layer (4).

20. The battery cell according to any one of claims 1 to 19, wherein: The negative electrode sheet (2) comprises a negative electrode main body (21) and a negative electrode ear (22) extending outward from the negative electrode main body (21) along a bending direction, and at least a portion of the area on the surface of the negative electrode main body (21) along the bending direction is a negative electrode active material layer; The negative electrode active material layer is disposed in a partial area of ​​the negative electrode ear portion (22).

21. The battery cell according to claim 20, wherein: The negative electrode active material layer is arranged on the surface of the negative electrode ear portion (22) and in a root region close to the negative electrode main body portion (21).

22. The battery cell according to any one of claims 1 to 21, wherein: The positive electrode sheet (1) comprises a positive electrode main body (11) and at least one positive electrode ear (12) extending outside the positive electrode main body (11) along a bending direction, at least a part of the surface of the positive electrode main body (11) is a positive electrode active material layer, and the surface of the positive electrode main body (11) also comprises a first insulating layer coating area (112) adjacent to the positive electrode active material layer, and the first insulating layer coating area (112) is used to insulate and isolate the positive electrode active material layer and the positive electrode ear (12).

23. The battery cell according to claim 22, wherein: The first insulating layer coating area (112) is located on a side of the positive electrode active material layer adjacent to the positive electrode ear portion (12); or The positive electrode active material layer and the first insulating layer coating area (112) are two parallel areas on the surface of the positive electrode main body (11), and are distributed in two layers on the surface of the positive electrode main body (11) along the bending direction.

24. The battery cell according to any one of claims 1 to 23, wherein: The barrier layer (4) is arranged opposite to a portion of the negative electrode plate (2) having the largest curvature.

25. The battery cell according to any one of claims 1 to 24, wherein: The barrier layer (4) comprises at least one of the following: an inorganic oxide, a high molecular polymer, a binder and an adhesive tape; or the barrier layer (4) comprises at least one of the following: an inorganic oxide, a high molecular polymer, a binder and an adhesive tape.

26. The battery cell according to claim 25, wherein: The adhesive tape includes an adhesive and a substrate, the substrate may be made of polyethylene and / or ethylene-vinyl acetate copolymer, and the adhesive paper may be made of at least one of polyethylene terephthalate, polyvinylidene fluoride, polyurethane, sodium polyacrylate, styrene-butadiene rubber, polyetherimide, carboxymethyl cellulose and acrylate.

27. The battery cell according to any one of claims 1 to 26, wherein: Both ends of the barrier layer (4) extending along the bending direction are located in the bending area.

28. The battery cell according to any one of claims 1 to 26, wherein: The electrode assembly has a straight region (P) connected to the bending region; One end of the barrier layer (4) extending in the bending direction is located in the straight zone (P), and the other end is located in the bending zone (C); or, both ends of the barrier layer (4) extending in the bending direction are located in the straight zone (P); or, both ends of the barrier layer (4) extending in the bending direction are located at the junction of the bending zone (C) and the straight zone (P).

29. The battery cell according to any one of claims 1 to 28, wherein: The electrode assembly comprises a straight region (P) connected to the bending region, the bending region comprises a first bending region and a second bending region, the first bending region and the second bending region are located on both sides of the straight region (P); The barrier layer is provided on the inner surface of at least the innermost positive electrode sheet (1) of the first bending zone and the second bending zone, and / or, the barrier layer is provided on the outer surface of at least the innermost positive electrode sheet (1) of the first bending zone and the second bending zone, and / or, the barrier layer is provided on the inner surface of at least the innermost negative electrode sheet (2) of the first bending zone and the second bending zone, and / or, the barrier layer is provided on the outer surface of at least the innermost negative electrode sheet (2) of the first bending zone and the second bending zone, and / or, the barrier layer is provided on the inner surface of at least the innermost isolation film of the first bending zone and the second bending zone, and / or, the barrier layer is provided on the outer surface of at least the innermost isolation film of the first bending zone and the second bending zone.

30. A battery, wherein: It comprises a box body and at least one battery cell according to any one of claims 1 to 29, wherein the battery cell is accommodated in the box body.

31. An electrical device, wherein: The electric device is configured to receive electric power provided from the battery according to claim 30.

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