Electrode assemblies and related batteries, devices, manufacturing methods, and manufacturing apparatus

Abstract

This application discloses an electrode assembly, as well as related batteries, devices, manufacturing methods, and manufacturing apparatuses. The electrode assembly includes at least one positive electrode plate and at least one negative electrode plate, where the total number of all positive electrode plates and all negative electrode plates is three or more, and the at least one positive electrode plate and the at least one negative electrode plate are wound around a winding axis to form a wound structure. In the wound structure, the positive electrode plate of the at least one positive electrode plate and the negative electrode plate of the at least one negative electrode plate are arranged overlapping each other along a direction perpendicular to the winding axis. Each positive electrode plate of the at least one positive electrode plate includes a positive electrode body portion, and at least a portion of the overlapping surface of the positive electrode body portion is a positive electrode active material region. Each negative electrode plate of the at least one negative electrode plate includes a negative electrode body portion, and at least a portion of the overlapping surface of the negative electrode body portion is a negative electrode active material region, and both ends of the negative electrode active material region along the winding axis extend beyond the corresponding ends of the adjacent positive electrode active material region.

Description

[Technical field]

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

[0002] Due to the advantages of small size, high energy density, high power density, multiple cycles, and long storage time, lithium ion batteries and the like are widely used in some electronic devices, electric vehicles, electric toys, and electric devices, for example, lithium ion batteries are currently widely used in mobile phones, laptops, battery cars, electric automobiles, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and power tools.

[0003] With the continuous development of lithium-ion battery technology, higher requirements are put forward for the performance of lithium-ion batteries, and lithium-ion batteries are expected to become smaller, lighter and store more energy, and therefore the energy density of lithium-ion batteries needs to be continuously improved.

[0004] Currently, there are several methods available to improve the energy density of lithium-ion batteries, for example, the energy density of lithium-ion batteries can be improved from the structure. For example, the proportion of the positive and negative active materials of the lithium-ion battery can be improved, and another method to improve the energy density of lithium-ion batteries is to reduce the thickness of the diaphragm. For another example, the energy density of lithium-ion batteries can be improved from the material, for example, different positive and negative active materials can be selected. For yet another example, the energy density of lithium-ion batteries can be improved by controlling the amount of electrolyte, for example, the energy density of lithium-ion batteries can be effectively improved by reducing the amount of electrolyte. For yet another example, the energy density of lithium-ion batteries can also be improved by improving the charge cut-off voltage.

[0005] However, no matter which of the above methods for improving the energy density of lithium-ion batteries is adopted, problems exist to a greater or lesser extent, for example, specific problems in cost, process, or safety. Summary of the Invention

[0006] The present application provides electrode assemblies, as well as related batteries, devices, manufacturing methods, and manufacturing apparatus, that overcome or at least partially solve the above problems.

[0007] According to a first aspect of the present application, there is provided an electrode assembly including at least one positive electrode plate and at least one negative electrode plate, the total number of all positive electrode plates and all negative electrode plates being 3 or more, the at least one positive electrode plate and the at least one negative electrode plate being wound around a winding axis to form a winding structure, the positive electrode plate in the at least one positive electrode plate and the negative electrode plate in the at least one negative electrode plate being arranged in a superimposed manner along a direction perpendicular to the winding axis, each positive electrode plate in the at least one positive electrode plate includes a positive electrode main body portion, at least a part of an area of ​​the superimposed surface of the positive electrode main body portion is a positive electrode active material region, and each negative electrode plate in the at least one negative electrode plate includes a negative electrode main body portion, at least a part of an area of ​​the superimposed surface of the negative electrode main body portion is a negative electrode active material region, and both ends of the negative electrode active material region along the winding axis extend beyond corresponding ends of the adjacent positive electrode active material regions.

[0008] In some embodiments, each of the two ends of the negative electrode active material region along the winding axis exceeds the corresponding end of the adjacent positive electrode active material region by 0.2 mm to 5 mm.

[0009] In some embodiments, the electrode assembly further comprises a plurality of diaphragms, wherein adjacent positive and negative plates are separated from one another by diaphragms.

[0010] In some embodiments, the positive electrode plate further includes at least one positive electrode tab portion extending outward from the positive electrode body portion along the direction of the winding axis, and the negative electrode plate further includes at least one negative electrode tab portion extending outward from the negative electrode body portion along the direction of the winding axis.

[0011] In some embodiments, a portion of the region of the positive electrode main body portion is a first insulating layer covered region, the first insulating layer covered region is disposed on a side of the positive electrode active material region adjacent to the positive electrode tab portion, and a first end of the negative electrode main body portion adjacent to the negative electrode tab portion along the direction of the winding axis is disposed in the first insulating layer covered region.

[0012] In some embodiments, the negative electrode active material region covers the entire overlapping surface of the negative electrode main body portion along the winding axis, and a second end of the negative electrode main body portion away from the negative electrode tab portion along the winding axis extends beyond the positive electrode active material region.

[0013] In some embodiments, when the number of the at least one positive plate is two or more, the positions of the first winding ends of the at least two positive plates are different, and / or when the number of the at least one negative plate is two or more, the positions of the second winding ends of the at least two negative plates are different.

[0014] In some embodiments, when the number of the at least one positive plate is two or more, the positions of the first winding start ends of the at least two positive plates are different, and / or when the number of the at least one negative plate is two or more, the positions of the second winding start ends of the at least two negative plates are different.

[0015] In some embodiments, the winding structure is flattened and includes a flattened region and a turn region disposed on either side of the flattened region, and the first winding end of the at least one positive plate is disposed in the turn region and / or the second winding end of the at least one negative plate is disposed in the turn region.

[0016] In some embodiments, the difference in the number of layers of electrode plates in different radial directions of the winding structure does not exceed a preset number of layers.

[0017] In some embodiments, the preset number of layers is less than or equal to the total number of all positive plates and all negative plates combined.

[0018] In some embodiments, the outermost and innermost layers of the wound structure are all negative plates.

[0019] According to a second aspect of the present application, there is provided a battery comprising a housing and the electrode assembly of the above embodiment, the electrode assembly being disposed within the housing.

[0020] According to a third aspect of the present application, there is provided a battery module including a plurality of the batteries according to the above embodiment.

[0021] According to a fourth aspect of the present application, there is provided a battery pack including a plurality of the battery modules according to the above embodiment.

[0022] According to a fifth aspect of the present application, there is provided a battery-based device, the device including the battery of the above embodiment, the battery being configured to supply electrical energy to the device.

[0023] According to a sixth aspect of the present application, there is provided a method for manufacturing an electrode assembly, the method including: providing at least one positive electrode plate and at least one negative electrode plate, wherein a total number of all positive electrode plates and all negative electrode plates is three or more; and winding the at least one positive electrode plate and the at least one negative electrode plate around a winding axis to form a winding structure, wherein in the winding structure, a positive electrode plate in the at least one positive electrode plate and a negative electrode plate in the at least one negative electrode plate are arranged in a superimposed state along a direction perpendicular to the winding axis, each positive electrode plate in the at least one positive electrode plate includes a positive electrode main body portion, at least a part of an area of ​​the superimposed surface of the positive electrode main body portion is a positive electrode active material region, and each negative electrode plate in the at least one negative electrode plate includes a negative electrode main body portion, at least a part of an area of ​​the superimposed surface of the negative electrode main body portion is a negative electrode active material region, and both ends of the negative electrode active material region along the winding axis extend beyond corresponding ends of the adjacent positive electrode active material regions.

[0024] According to a seventh aspect of the present application, there is provided an electrode assembly manufacturing apparatus including: an electrode plate arrangement mechanism configured to provide at least one positive electrode plate and at least one negative electrode plate, wherein a total number of all positive electrode plates and all negative electrode plates is three or more; and a winding mechanism configured to wind the at least one positive electrode plate and the at least one negative electrode plate around a winding axis to form a winding structure, wherein in the winding structure, one positive electrode plate among the plurality of positive electrode plates and one negative electrode plate among the plurality of negative electrode plates are alternately arranged along a direction perpendicular to the winding axis, each positive electrode plate includes a positive electrode body portion, at least a part of a region of the positive electrode body portion along the winding axis is a positive electrode active material region, and each negative electrode plate includes a negative electrode body portion, at least a part of a region of the negative electrode body portion along the winding axis is a negative electrode active material region, and both ends of the negative electrode active material region along the winding axis extend beyond corresponding ends of the adjacent positive electrode active material regions.

[0025] The electrode assembly of the present embodiment controls the extent to which the negative electrode active material region exceeds the positive electrode active material region, thereby reducing the reserve size of the negative electrode active material region and reserving space for increasing the area of ​​the positive electrode active material region and the negative electrode active material region, thereby further reducing the cost and improving the energy density of the electrode assembly. [Brief description of the drawings]

[0026] The drawings described herein provide further understanding of the present application and are incorporated in and constitute a part of the present application. The exemplary embodiments and the description thereof are intended to be illustrative of the present application and are not intended to unduly limit the present application.

[0027] [Figure 1] Schematic diagrams of the exterior of some embodiments of a vehicle that employs the battery of the present application. [Diagram 2] 1 is a structural schematic diagram of some embodiments of the battery pack of the present application; [Diagram 3] 1 is a structural schematic diagram of some embodiments of the battery module of the present application; [Figure 4]1 is an exploded view of some embodiments of the battery of the present application. [Diagram 5] FIG. 1 is a side view of some embodiments of the electrode assembly of the present application after flattening. [Figure 6] 1 is a structural schematic diagram of some embodiments of a positive electrode plate in an electrode assembly of the present application; [Figure 7] 1 is a structural schematic diagram of some embodiments of a negative electrode plate in an electrode assembly of the present application; [Figure 8] FIG. 1 is a side view of some embodiments in which positive and negative plates are alternated in the electrode assembly of the present application; [Figure 9] Enlarged view of part A in Figure 8 [Figure 10] FIG. 1 is a structural schematic diagram of some embodiments of the present application in which the positive and negative tabs are located at the same end of the body along the winding axis. [Figure 11] FIG. 1 is a structural schematic diagram of some embodiments of the present application in which the positive and negative tabs are located at different ends of the body along the winding axis. [Figure 12] FIG. 1 is a cross-sectional view of a first embodiment of a flat electrode assembly of the present application taken along a plane perpendicular to the winding axis. [Figure 13] FIG. 2 is a cross-sectional view of a second embodiment of the flat electrode assembly of the present application taken along a plane perpendicular to the winding axis. [Figure 14] FIG. 1 is a cross-sectional view of a third embodiment of the flat electrode assembly of the present application taken along a plane perpendicular to the winding axis. [Figure 15] FIG. 1 is a cross-sectional view of a fourth embodiment of the flat electrode assembly of the present application taken along a plane perpendicular to the winding axis; [Figure 16] FIG. 11 is a cross-sectional view of a fifth embodiment of the flat electrode assembly of the present application taken along a plane perpendicular to the winding axis. [Figure 17] FIG. 1 is a cross-sectional view of a first embodiment of a cylindrical electrode assembly of the present application taken along a plane perpendicular to the winding axis; [Figure 18] FIG. 2 is a cross-sectional view of a second embodiment of the present cylindrical electrode assembly taken along a plane perpendicular to the winding axis; [Figure 19] FIG. 1 is a cross-sectional view of a third embodiment of a cylindrical electrode assembly of the present application taken along a plane perpendicular to the winding axis; [Figure 20]FIG. 1 is a cross-sectional view of a fourth embodiment of the present cylindrical electrode assembly taken along a plane perpendicular to the winding axis; [Figure 21] 1 is a flow diagram of some embodiments of a method for manufacturing an electrode assembly of the present application; [Figure 22] FIG. 1 is a structural schematic diagram of some embodiments of an apparatus for manufacturing an electrode assembly according to the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] In order to make the objectives, technical solutions and effects of the embodiments of the present application clearer, a clear and complete description of the technical solutions of the embodiments of the present application is given below in combination with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part, not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts are all within the protection scope of the present application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by those skilled in the art of the present application, and the terms used in the application specification herein are not intended to limit the present application but merely to describe certain embodiments, and the terms "including" and "having" and any variations thereof in the specification, claims, and the above brief description of the drawings of the present application are intended to include non-exclusive inclusions. Terms such as "first" and "second" in the specification, claims, or the above drawings of the present application are used to distinguish different objects, not to describe a particular order or primary or secondary relationship.

[0030] Reference to an "embodiment" in this document means that a particular feature, structure, or property described in connection with the embodiment may be included in at least one embodiment of the present application. The appearance of such phrases in various places in this specification does not necessarily refer to the same embodiment, nor does it refer to separate or alternative embodiments that are mutually exclusive with other embodiments. Those skilled in the art can explicitly and implicitly understand that the embodiments described in this document can be combined with other embodiments.

[0031] The term "and / or" in this text simply describes the occurrence relationship of related objects and represents the existence of three relationships. For example, A and / or B can represent the presence of only A, the simultaneous presence of A and B, or the presence of only B. Furthermore, the symbol " / " in this text generally represents an "or" relationship between the related objects before and after it.

[0032] In this application, the term "a plurality of" means two or more (including two), and similarly, a "plurality of groups" means two or more groups (including two groups), and a "plurality of pieces" means two or more pieces (including two pieces).

[0033] The electrode assembly and its manufacturing method, as well as the battery, battery module, and battery pack described in the embodiments of the present application, are all applicable to various devices that use batteries, such as mobile phones and portable devices, laptops, battery cars, electric cars, ships, spacecraft, electric toys, electric tools, etc. For example, the spacecraft include airplanes, rockets, space shuttles, and spaceships, and the like, the electric toys include fixed or movable electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and electric tools used in railways, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, electric impact drills, concrete vibrators, and electric planers.

[0034] The electrode assemblies and manufacturing methods thereof, as well as the batteries, battery modules, and battery packs described in the embodiments of the present application are not only applicable to the above devices, but also to all devices that use batteries. For ease of explanation, however, the following embodiments will be described using an electric vehicle as an example.

[0035] For example, FIG. 1 is a structural schematic diagram of a vehicle 100 in an embodiment of the present application. The vehicle 100 can be an oil-fueled vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a battery electric vehicle, a hybrid electric vehicle, or an extended range vehicle. The battery pack 200 can be disposed inside the vehicle 100. For example, the battery pack 200 can be disposed at the bottom, the front end, or the rear end of the vehicle 100. The battery pack 200 can be used for the power source of the vehicle 100. For example, the battery pack 200 can serve as the operating power source of the vehicle 100 and can serve as the circuit system of the vehicle 100. For example, the battery pack 200 can meet the power demand of the vehicle 100 during starting, navigation, and operation of the vehicle 100. In other embodiments of the present application, the battery pack 200 can not only serve as the operating power source of the vehicle 100, but also serve as the driving power source of the vehicle 100, and can be used in place of or partially used in place of fuel oil or natural gas to provide driving force for the vehicle 100.

[0036] In order to meet different requirements for electrical use, the battery pack 200 may include one battery module or multiple battery modules, and multiple battery modules may be connected in series, in parallel, or in series and parallel. The serial and parallel connections refer to a combination of serial and parallel connections. For example, FIG. 2 is a structural schematic diagram of a battery pack 200 of another embodiment of the present application. The battery pack 200 includes a first housing 201, a second housing 202, and multiple battery modules 300. The shapes of the first housing 201 and the second housing 202 are determined according to the combined shapes of the multiple battery modules 300. Both the first housing 201 and the second housing 202 are provided with openings. For example, both the first housing 201 and the second housing 202 may be hollow rectangular parallelepipeds with only one surface being an opening surface. That is, there is no housing wall on the surface, and the inside and outside of the housing are in communication. The first housing 201 and the second housing 202 are buckled together at the opening to form a closed housing of the battery pack 200. After connecting the multiple battery modules 300 in parallel, in series, or in series and parallel, the multiple battery modules 300 are placed in the housing formed after buckling the first housing 201 to the second housing 202.

[0037] In another embodiment of the present application, when the battery pack 200 includes a battery module 300, the battery module 300 is disposed within a housing formed after buckling the first housing 201 to the second housing 202.

[0038] Electricity generated by the one or more battery modules 300 is conducted through the housing by a conductive mechanism (not shown).

[0039] According to different power demands, the battery module 300 can include one or more batteries, and as shown in FIG. 3, the battery module 300 includes a plurality of batteries 400. The plurality of batteries 400 can be connected by series connection, parallel connection, or series and parallel connection to achieve large capacity or high power. For example, the batteries 400 include, but are not limited to, lithium ion secondary batteries, lithium ion primary batteries, lithium sulfur batteries, sodium lithium ion batteries, or magnesium ion batteries. The batteries 400 can be cylindrical, flat, rectangular, or other shapes.

[0040] In another embodiment of the present application, a plurality of batteries 400 can be stacked on top of each other and connected in series, parallel, or in series and parallel. In another embodiment of the present application, each battery 400 can be square, cylindrical, or other shapes. For example, FIG. 4 is a structural schematic diagram of a battery 400 in another embodiment of the present application, the battery 400 includes one or more electrode assemblies 10, a housing 20, and an end cover assembly 40. The shape of the housing 20 can be determined according to the combined shape of the one or more electrode assemblies 10. For example, the housing 20 can be a hollow rectangular parallelepiped, cube, or cylinder. Furthermore, one of the surfaces of the housing 20 is provided with an opening, so that one or more electrode assemblies 10 can be placed inside the housing 20. For example, when the housing 20 is a hollow rectangular parallelepiped or cube, one of the planes of the housing 20 is an open plane, that is, there is no housing wall on that plane, and the inside and outside of the housing 20 are in communication with each other. If the housing 20 is a hollow cylinder, the circular side of the housing 20 is the open side, i.e., the circular side is free of housing walls and provides communication between the inside and outside of the housing 20. The end cover assembly 40 is connected to the housing 20 at the opening of the housing 20 to form a closed housing that contains the battery 400. The housing 20 is filled internally with an electrolyte.

[0041] The end cover assembly 40 includes an end cover 41 and two terminals 42. The end cover 41 is basically flat. The two terminals 42 are disposed on the flat surface of the end cover 41 and penetrate the flat surface of the end cover 41. The two terminals 42 are a positive electrode terminal and a negative electrode terminal, respectively. A collector member 30 is provided corresponding to each terminal 42. The collector member 30 is disposed between the end cover 41 and the electrode assembly 10.

[0042] 4, each electrode assembly 10 is provided with a positive electrode tab 12' and a negative electrode tab 22'. The positive electrode tab 12' of one or more electrode assemblies 10 is connected to a positive terminal via a collector member 30, and the negative electrode tab 22' of one or more electrode assemblies 10 is connected to a negative terminal via another collector member 30.

[0043] In another embodiment of the present application, an explosion-proof valve 43 can be further provided on the flat surface of the end cover 41. The explosion-proof valve 43 can be a part of the flat surface of the end cover 41, and can also be welded to the flat surface of the end cover 41. For example, the explosion-proof valve 43 has a nick. The depth of the nick is smaller than the thickness of other areas of the explosion-proof valve 43 except the nick, so as to achieve the purpose of not penetrating the explosion-proof valve 43. That is, in a normal state, the explosion-proof valve 43 is combined with the end cover 41 in a sealed state. The end cover assembly 40 is connected to the housing 20 at the opening of the housing 20 through the end cover 41 to form a housing that contains the battery 400. The space formed by the housing is sealed and airtight. If the battery 400 generates excess gas within the housing and the gas expands to cause the air pressure within the housing to exceed a preset value, the explosion-proof valve 43 cracks at the nick, connecting the inside and outside of the housing and allowing the gas to be released to the outside through the cracked part of the explosion-proof valve 43, thereby preventing further explosion.

[0044] A single or multiple electrode assemblies 10 may be disposed in the battery 400 according to actual usage requirements. As shown in FIG. 4, at least two independent electrode assemblies 10 are provided inside the battery 400. In another embodiment of the present application, as shown in FIG. 5, the electrode assembly 10 includes at least one positive electrode plate 1 and at least one negative electrode plate 2. The at least one positive electrode plate 1 and the at least one negative electrode plate 2 are wound around a winding axis K to form a winding structure. In this winding structure, the positive electrode plate of the at least one positive electrode plate and the negative electrode plate of the at least one negative electrode plate are arranged to overlap each other along a direction perpendicular to the winding axis.

[0045] The number of at least one positive plate 1 and at least one negative plate 2 can be the same or different. For example, the electrode assembly 10 includes one, two, three, or four positive plates 1 and one, two, three, or four negative plates 2. In some embodiments, the total number of all positive plates 1 and all negative plates 2 is three or more. For example, the electrode assembly 10 includes one positive plate 1 and two negative plates 2, or includes two positive plates 1 and one negative plate 2, or includes two positive plates 1 and two negative plates 2, or includes one positive plate 1 and three negative plates 2, or includes three positive plates 1 and one negative plate 2, or includes three positive plates 1 and three negative plates 2.

[0046] In another embodiment of the present application, the shape of each positive electrode plate 1 is basically the same as the shape of each negative electrode plate 2. For example, after the winding structure is flattened, the positive electrode plate 1 and the negative electrode plate 2 are basically strip-shaped. For example, the positive electrode plate 1 and the negative electrode plate 2 can be strip-shaped with a length of 5 to 20 m. The difference in length between the positive electrode plate 1 and the negative electrode plate 2 is within a preset range, and the width dimensions are basically the same. After stacking at least one positive electrode plate 1 and at least one negative electrode plate 2, the at least one positive electrode plate 1 and at least one negative electrode plate 2 are wound along the strip direction to obtain a winding structure. This winding structure has a winding axis K, and the overlapping surface where the at least one positive electrode plate 1 is overlapped with the at least one negative electrode plate 2 is basically parallel to the winding axis K.

[0047] In another embodiment of the present application, at least one positive electrode plate 1 and at least one negative electrode plate 2 can be superimposed in a plurality of forms. For example, when at least one positive electrode plate 1 is two or more positive electrode plates 1 and at least one negative electrode plate 2 is two or more negative electrode plates 2, after the winding structure is flattened, one positive electrode plate 1 and one negative electrode plate 2 can be superimposed alternately in sequence, two or more positive electrode plates 1 and one negative electrode plate 2 can be superimposed alternately in sequence, and one positive electrode plate 1 and two or more negative electrode plates 2 can be superimposed alternately in sequence. The superimposition of a plurality of positive electrode plates 1 and a plurality of negative electrode plates 2 can also be understood as at least one negative electrode plate 2 being included between two adjacent positive electrode plates 1, or at least one positive electrode plate 1 being included between two adjacent negative electrode plates 2.

[0048] When at least one positive electrode plate 1 and at least one negative electrode plate 2 are overlapped, a diaphragm 3 is further disposed between every adjacent positive electrode plate 1 and every adjacent negative electrode plate 2. The diaphragm 3 is configured to separate the adjacent positive electrode plate 1 and the adjacent negative electrode plate 2, so that the adjacent positive electrode plate and the adjacent negative electrode plate are not short-circuited with each other.

[0049] In another embodiment of the present application, electrode plates of different polarities are adjacent to each other. That is, a positive electrode plate 1 is adjacent to a negative electrode plate 2 means that there are no electrode plates between the positive electrode plate 1 and the negative electrode plate 2 other than at least one layer of the diaphragm 3, for example, there are no other positive electrode plates 1 or negative electrode plates 2 between the positive electrode plate 1 and the negative electrode plate 2. It can also be understood as the positive electrode plate 1 and the negative electrode plate 2 being most directly adjacent to each other. For example, based on one electrode plate (e.g., a positive electrode plate 1) having one polarity, that electrode plate with that polarity and the first layer of electrode plates with a different polarity adjacent to that electrode plate with that polarity (e.g., a negative electrode plate 2) are called adjacent electrode plates.

[0050] In other embodiments of the present application, two electrode plates of the same polarity being adjacent means that there is only one electrode plate of the other polarity between the two electrode plates of the same polarity. For example, two positive electrode plates 1 being adjacent means that there is only one negative electrode plate 2 between the two positive electrode plates 1, and two negative electrode plates 2 being adjacent means that there is only one positive electrode plate 1 between the two negative electrode plates 2. In other embodiments of the present application, if there is no other electrode plate of a different polarity between the two electrode plates of the same polarity, the two electrode plates of the same polarity can be considered as one electrode plate.

[0051] In another embodiment of the present application, when there is no other electrode plate and diaphragm of a different polarity between two or more electrode plates of the same polarity, the two or more electrode plates of the same polarity can be regarded as one electrode plate group, and therefore, when stacking, the electrode plate group of the same polarity and another electrode plate group or a single electrode plate of a different polarity are stacked in an alternating order. For example, two or more positive electrode plates constitute a positive electrode plate group, and two or more negative electrode plates constitute a negative electrode plate group. The stacking can be as follows: a positive electrode plate group and a negative electrode plate group are stacked in an alternating order, a positive electrode plate group and a single negative electrode plate are stacked in an alternating order, or a negative electrode plate group and a single positive electrode plate are stacked in an alternating order.

[0052] Since a group of electrode plates of the same polarity can be regarded as one electrode plate, for ease of explanation, the one electrode plate described below may not only be one electrode plate, but also be an electrode plate group consisting of multiple electrode plates of the same polarity.

[0053] However, regardless of the method of stacking, at least one layer of membrane 3 is disposed between adjacent electrode plates of different polarities.

[0054] In another embodiment of the present application, the diaphragm 3 includes a diaphragm base layer and a functional layer. The diaphragm base layer may be at least one selected from polypropylene, polyethylene, ethylene-propylene copolymer, and polybutylene terephthalate. The functional layer may be a mixed layer of a ceramic oxide and a binder. In another embodiment of the present application, after the wound structure is flattened, the diaphragm 3 is a thin film that exists separately and is basically in a strip shape, for example, in a strip shape with a length of 5 to 20 m. In another embodiment of the present application, the diaphragm 3 is coated on the surface of the positive electrode plate 1 or the negative electrode plate 2, that is, the diaphragm 3 and the positive electrode plate 1 or the negative electrode plate 2 are integrally formed.

[0055] For ease of explanation, the following embodiment will be described by taking as an example a case where one positive electrode plate 1 and one negative electrode plate 2 are alternately stacked in order, and one diaphragm 3 is disposed between the adjacent positive electrode plate 1 and negative electrode plate 2. For example, FIG. 5 is a structural schematic diagram of an electrode assembly 10 in another embodiment of the present application after the winding structure is flattened. The electrode assembly 10 includes two positive electrode plates 1 and two negative electrode plates 2, and each positive electrode plate 1 and each negative electrode plate 2 may have a strip-like structure before winding. The two positive electrode plates 1 and the two negative electrode plates 2 are stacked in the thickness direction of the electrode plates, and a diaphragm 3 is disposed between every adjacent positive electrode plate 1 and negative electrode plate 2. That is, one positive electrode plate 1 and one negative electrode plate 2 are alternately stacked in order, and a diaphragm 3 is disposed between every adjacent positive electrode plate 1 and negative electrode plate 2. The diaphragm 3 can be not only coated on the overlapping surface of the positive electrode plate 1 and the negative electrode plate 2, but also can be a separate diaphragm. The overlapping plane on which the two positive electrode plates 1 and the two negative electrode plates 2 are overlapped is essentially parallel to the winding axis K of the winding structure of the electrode assembly 10.

[0056] The structure of the positive electrode plate 1 can be as shown in FIG. 6, which is a structural schematic diagram of the positive electrode plate 1 in another embodiment of the present application. The positive electrode plate 1 includes a positive electrode body portion 11 and at least one positive electrode tab portion 12 extending outward from the positive electrode body portion 11 along the direction of the winding axis K. At least a part of the area along the winding axis K on the overlapping surface of the positive electrode body portion 11 is a positive electrode active material region 111. The positive electrode active material region 111 can be coated with a positive electrode active material. For example, the positive electrode active material can be a ternary material, lithium manganate, or lithium iron phosphate.

[0057] In another embodiment of the present application, a portion of the overlapping surface region of the positive electrode main body portion 11 further includes a first insulating layer covered region 112. The first insulating layer covered region 112 is disposed on the side of the positive electrode active material region 111 adjacent to the positive electrode tab portion 12.

[0058] For example, the positive electrode active material region 111 and the first insulating layer covered region 112 are distributed on the overlapping surface of the positive electrode main body 11 along both end sides of the winding axis K, and the positive electrode tab portion 12 and the first insulating layer covered region 112 belong to the same end side of the positive electrode main body 11. For example, the positive electrode tab portion 12 extends from the first insulating layer covered region 112 to the outside of the positive electrode main body 11 along the direction of the winding axis K.

[0059] In another embodiment of the present application, the positive electrode active material region 111 and the first insulating layer covered region 112 are distributed on the overlapping surface of the positive electrode main body portion 11 along both ends of the winding axis K, but this can also be understood as the positive electrode active material region 111 and the first insulating layer covered region 112 being basically parallel regions on the overlapping surface of the positive electrode main body portion 11 and being distributed in two layers on the overlapping surface of the positive electrode main body portion 11 along the winding axis K, in other words, the positive electrode active material region 111 and the first insulating layer covered region 112 being basically parallel and being distributed in two layers on the overlapping surface of the positive electrode main body portion 11 along the band-shaped direction of the positive electrode plate 1.

[0060] In another embodiment of the present application, the first insulating layer covering region 112 can be disposed in the connection portion between the positive electrode main body portion 11 and the positive electrode tab portion 12. For example, the first insulating layer covering region 112 is disposed in the portion where the positive electrode main body portion 11 is connected to the positive electrode tab portion 12 on the overlapping surface of the positive electrode main body portion 11 in order to separate the surface of the positive electrode tab portion 12 from the positive electrode active material region 111. In another embodiment of the present application, not only is the first insulating layer covering region 112 provided in a portion of the region connected to the positive electrode tab portion 12 extending outward on the overlapping surface of the positive electrode main body portion 11, but also the second insulating layer covering region 121 is provided in a portion of the region connected to the overlapping surface of the positive electrode tab portion 12 on the overlapping surface of the positive electrode tab portion 12. That is, the second insulating layer covering region 121 can cover the root region of the positive electrode tab portion 12 adjacent to the positive electrode main body portion 11.

[0061] In another embodiment of the present application, the surface of the first insulating layer covering region 112 is coated with an insulating material. The insulating material includes an inorganic filler and a binder. The inorganic filler includes at least one 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 binder includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyacrylic acid, polyacrylic acid ester, polyacrylate-acrylate, polyacrylonitrile-acrylic acid, and polyacrylonitrile-acrylic acid ester.

[0062] In other embodiments of the present application, each positive electrode plate 1 may include one, two, or three or more positive electrode tab portions 12. When the positive electrode plate 1 includes two or more positive electrode tab portions 12, all of the positive electrode tab portions 12 are disposed on the same side of the positive electrode plate 1 along the winding axis K. For example, as shown in FIG. 6, the positive electrode plate 1 includes three positive electrode tab portions 12, which are disposed on the same side of the positive electrode plate 1 along the winding axis K.

[0063] The structure of the negative electrode plate 2 can be as shown in FIG. 7, which is a structural schematic diagram of the negative electrode plate 2 of another embodiment of the present application. The negative electrode plate 2 includes a negative electrode main body portion 21 and a negative electrode tab portion 22 extending outward from the negative electrode main body portion 21 along the direction of the winding axis K. At least a part of the region along the winding axis K on the overlapping surface of the negative electrode main body portion 21 is a negative electrode active material region 211. The negative electrode active material region 211 is configured to coat the negative electrode active material. The negative electrode active material can be graphite or silicon.

[0064] In another embodiment of the present application, not only is the negative electrode active material region 211 provided in a portion of the region of the overlapping surface of the negative electrode main body portion 21, but the negative electrode active material region 211 is also provided in a portion of the region on the overlapping surface of the negative electrode tab portion 22 that is connected to the overlapping surface of the negative electrode main body portion 21. That is, a portion of the region of the negative electrode tab portion 22 is the negative electrode active material region 211. For example, the negative electrode active material region 211 can cover a root region of the negative electrode tab portion 22 adjacent to the negative electrode main body portion 21.

[0065] In another embodiment of the present application, the negative electrode active material region 211 covers the entire overlapping surface along the winding axis K of the negative electrode main body portion 21, as shown in FIG.

[0066] In another embodiment of the present application, when the positive electrode plate 1 and the negative electrode plate 2 are overlapped with each other, i.e., in a wound structure, both ends of the negative electrode active material region 211 of the negative electrode plate 2 along the winding axis K extend beyond the adjacent ends of the positive electrode active material region 111 of the positive electrode plate 1.

[0067] In some embodiments, both ends of the negative electrode active material region 211 along the winding axis K extend beyond the corresponding ends of the adjacent positive electrode active material region 111 by a range of 0.2 mm to 5 mm (e.g., 0.2 mm, 0.5 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm, etc.). Both ends of the negative electrode active material region 211 along the winding axis K can extend beyond the corresponding ends of the positive electrode active material region 111 by the same amount or by different amounts.

[0068] When multiple positive plates 1 and multiple negative plates 2 are stacked on each other, the resulting cross-sectional view of the winding structure may be as shown in Figures 8 and 9. The stacking method between at least one positive plate 1 and at least one negative plate 2 is that one positive plate 1 and one negative plate 2 are stacked alternately in sequence, and adjacent positive plates 1 and negative plates 2 are separated by a diaphragm 3, where K is the winding axis K of the winding structure.

[0069] 6 to 9 in combination, after the positive electrode tab portion 12 is cut off from the positive electrode plate 12, a burr is likely to be generated on the edge of the positive electrode main body portion 11, and in order to avoid the phenomenon that the burr may punch a hole in the diaphragm 3 and lead to a short circuit between the positive electrode plate 1 and the negative electrode plate 2, the region of the positive electrode main body portion 11 of this embodiment adjacent to the positive electrode tab portion 12 may be set as an empty foil region C. The empty foil region C extends beyond the edge of the negative electrode plate 21 along the direction of the winding axis K, thereby avoiding the risk of the burr coming into contact with the negative electrode plate 2 after the edge of the positive electrode main body portion 11 punches a hole in the diaphragm 3 in the above case, and further avoids the problem of a short circuit between the positive electrode plate 1 and the negative electrode plate 2 because the gap between the empty foil region and the protruding amount is large and metal chips are likely to enter the gap.

[0070] In this embodiment, a first insulating layer covered region 112 is disposed in the positive electrode main body 11, and a first end portion of the negative electrode main body 21 adjacent to the negative electrode tab portion 22 along the direction of the winding axis K is disposed in this first insulating layer covered region 112. This satisfies that the negative electrode active material region 211 exceeds the adjacent positive electrode active material region 111 along the winding axis K, thereby reducing the risk of a short circuit between the positive electrode plate 1 and the negative electrode plate 2 after metal scraps perforate the diaphragm 3.

[0071] In another embodiment of the present application, the second end of the negative electrode main body portion 21 of the negative electrode plate 2, which is away from the negative electrode tab portion 22 along the direction of the winding axis K, extends beyond the positive electrode active material region 111 of the positive electrode plate 1.

[0072] In another embodiment of the present application, a region of the negative electrode main body portion 21 of the negative electrode plate 2 that is separated from the negative electrode tab portion 22 along the direction of the winding axis K is set as a vacant foil region.

[0073] In another embodiment of the present application, a second insulating layer covered region 121 is provided in a part of the region connected to the overlapping surface of the positive electrode main body portion 11 on the overlapping surface of the positive electrode tab portion 12. This effectively reduces the risk of a short circuit caused by contact between the root region of the positive electrode tab portion 12 and the negative electrode active material region 211.

[0074] After the electrode assembly 10 is wound and formed, all the positive electrode tab parts 12 are superimposed together to form the positive electrode tabs of the electrode assembly 10, and are welded to the corresponding collector members. In addition, in order to avoid the risk of short circuit caused by the following, that is, after welding, the non-welded areas of the multiple positive electrode tab parts 12 are in a dispersed state, while the tab parts are thin, so that the positive electrode tab parts 12 are easily deformed and pressed between the positive electrode plate 1 and the negative electrode plate 2 in the process of constructing the electrode assembly 10, the first insulating layer covered area 112 is disposed on the positive electrode plate 1 of this embodiment to achieve the effect of insulation protection. Even if the positive electrode tab part 12 is inserted between the positive electrode plate 1 and the negative electrode plate 2, the first insulating layer covered area 112 can effectively separate the positive electrode plate 1 from the negative electrode plate 2. This reduces the risk of short circuit and improves the safety performance of the battery.

[0075] In another embodiment of the present application, in order to retain a portion of the negative electrode active material at the root portion of the negative electrode tab portion 22 of the negative electrode plate 2, the cutter can act directly on the negative electrode active material during cutting, reducing burrs at the cutting point and reducing the risk of perforating the diaphragm 3.

[0076] In another embodiment of the present application, when the positive electrode plate 1 and the negative electrode plate 2 are overlapped, that is, in a wound structure, the positive electrode plate 1 of the negative electrode plate 2 and the positive electrode tab portion 12 of the negative electrode plate 22 can be arranged not only on the same side along the direction of the winding axis K of the wound structure, but also on different sides.

[0077] For example, each positive electrode plate 1 can include one or two or three or more positive electrode tab portions 12, and when the positive electrode plate 1 includes two or more positive electrode tab portions 12, all of the positive electrode tab portions 12 are disposed on the same side of the positive electrode plate 1 along the winding axis K. Each negative electrode plate 2 can include one or two or three or more negative electrode tab portions 22, and when the negative electrode plate 2 includes two or more negative electrode tab portions 22, all of the negative electrode tab portions 22 are disposed on the same side of the negative electrode plate 2 along the winding axis K.

[0078] In another embodiment of the present application, all of the positive electrode tab portions 12 and all of the negative electrode tab portions 22 are disposed on the same side of the electrode assembly 10-1 along the winding axis K, as shown in FIG.

[0079] In another embodiment of the present application, all of the positive electrode tab portions 12 and all of the negative electrode tab portions 22 are disposed on different sides of the electrode assembly 10-2 along the winding axis K, as shown in FIG.

[0080] For example, the electrode assembly 10 includes at least one positive electrode plate 1 and at least one negative electrode plate 2, and the at least one positive electrode plate 1 and the at least one negative electrode plate 2 are wound around a winding axis K to form a wound structure. All the positive electrode tab portions 12 of all the positive electrode plates 1 essentially overlap each other, and all the negative electrode tab portions 22 of all the negative electrode plates 2 essentially overlap each other. In addition, all the positive electrode tab portions 12 of all the positive electrode plates 1 and all the negative electrode tab portions 22 of all the negative electrode plates 2 are respectively disposed on both sides of the wound structure along the direction of the winding axis K, or all the positive electrode tab portions 12 and all the negative electrode tab portions 22 are disposed on the same side of the electrode assembly 10 along the winding axis K.

[0081] In other embodiments of the present application, when the number of at least one positive electrode plate 1 is two or more, the positions of the first winding ends E of at least two positive electrode plates 1 are different, for example, the positions of the first winding ends E of all positive electrode plates 1 are different from each other, and / or, when the number of at least one negative electrode plate 2 is two or more, the positions of the second winding ends E' of at least two negative electrode plates 2 are different, for example, the positions of the second winding ends E' of all negative electrode plates 2 are different.

[0082] The electrode assembly 10 expands during the use process, and exerts an action force on the housing 20 after the expansion of the electrode assembly 10, while the housing 20 exerts a reaction force on the electrode assembly 10. With respect to the electrode assembly 10 of the present application, the winding ends of at least two positive electrode plates 1 are set at different positions, and / or the winding ends of at least two negative electrode plates 2 are set at different positions. That is, the winding ends of at least two positive electrode plates 1 are arranged in a staggered manner in the circumferential direction of the winding structure, and / or the winding ends of at least two negative electrode plates 2 are arranged in a staggered manner in the circumferential direction of the winding structure. Such a structure can prevent the formation of a thick step after overlapping the winding ends of multiple positive electrode plates 1 or multiple negative electrode plates 2, and can alleviate the problem of stress concentration at the winding ends of the electrode plates when the outer layer of the winding structure is subjected to the reaction force of the housing 20, so that the winding structure 10' is subjected to uniform stress at different circumferential positions. This prevents significant deformation of the wound structure or the active material from falling off in some areas with high stress, improving the operating performance and reliability of the battery after long-term use.

[0083] In other embodiments of the present application, when the number of at least one positive electrode plate 1 is two or more, the positions of the first winding starting ends S of at least two positive electrode plates 1 are different, for example, the positions of the first winding starting ends S of all positive electrode plates 1 are different, and / or, when the number of at least one negative electrode plate 2 is two or more, the positions of the second winding starting ends S' of at least two negative electrode plates 2 are different, for example, the positions of the second winding starting ends S' of all negative electrode plates 2 are different.

[0084] The electrode assembly 10 expands during the use process, and in the electrode assembly 10 of the present application, the first winding start ends S of at least two positive electrode plates 1 are set at different positions, and / or the winding start ends S' of at least two negative electrode plates 2 are set at different positions. That is, the first winding start ends S of at least two positive electrode plates 1 are arranged in a staggered manner in the circumferential direction of the winding structure, and / or the second winding start ends S' of at least two negative electrode plates 2 are arranged in a staggered manner in the circumferential direction of the winding structure. Thus, the positions of the winding start ends of the positive electrode plates 1 and / or the negative electrode plates 2 are different, which can prevent the formation of thick steps at the winding start ends of the multiple positive electrode plates 1 or multiple negative electrode plates 2, and can alleviate the problem of stress concentration at the winding start ends of the electrode plates, so that the winding structure is subjected to uniform stress at different circumferential positions. This prevents significant deformation of the wound structure or the active material from falling off in some areas with high stress, improving the operating performance and reliability of the battery after long-term use.

[0085] In another embodiment of the present application, the difference in the number of layers of the electrode plates in different radial directions of the winding structure does not exceed the number of preset layers. For example, the preset number of layers is equal to or less than the total number of the plurality of positive electrode plates 1 and the plurality of negative electrode plates 2. For example, after winding two positive electrode plates 1 and two negative electrode plates 2, in one of the radial directions of the winding structure, the number of layers of the electrode plates (including all the positive electrode plates 1 and the negative electrode plates 2) is 8, and in the other radial direction of the winding structure, the number of layers of the electrode plates is a minimum of 8 and a maximum of 12. That is, the preset number of layers is equal to or less than the sum of the numbers of the two positive electrode plates 1 and the two negative electrode plates 2 (in this case, the sum is 4).

[0086] When the electrode assembly 10 expands and comes into contact with the housing 20, the housing 20 exerts a reaction force on the electrode assembly 10. If the difference in the number of layers of the electrode plates does not exceed the number of layers preset in different radial directions of the winding structure, the stress on the electrode assembly 10 at each point in the circumferential direction will be more uniform, thereby preventing the increase in performance difference at individual points of the electrode assembly 10 in the use process. For example, two positive electrode plates 1 are arranged, two negative electrode plates 2 are arranged, the number of preset layers is not more than 4, and the smaller the difference in the number of layers of the electrode plates, the more uniform the stress on the electrode assembly 10 at each point in the circumferential direction of the winding structure will be.

[0087] In another embodiment of the present application, the outermost and innermost layers of the wound structure are both negative electrode plates 2.

[0088] The outermost layer and the innermost layer of the winding structure are both negative electrode plates 2. The material of the positive electrode active material in the positive electrode plate 1 is usually a ternary material, lithium manganate, or lithium iron phosphate, etc., and the material of the negative electrode active material in the negative electrode plate 2 is usually graphite or silicon. Since the material of the positive electrode active material is more expensive than the material of the negative electrode active material, the outermost layer and the innermost layer of the winding structure are both coated by the negative electrode plate 2, so that the positive electrode active material of the positive electrode plate 1 can be fully utilized. This not only improves the energy utilization rate of the winding structure, but also reduces the difficulty of the manufacturing process of the electrode assembly 10.

[0089] Optionally, a positive electrode plate 1 is employed in at least one of the outermost and innermost layers of the winding structure, and in order to reduce the manufacturing cost of the electrode assembly 10, for the positive electrode plate 1 arranged in the outermost or innermost layer, it is not necessary to coat the positive electrode active material on the surface of the positive electrode plate 1 that is away from the negative electrode plate 2.

[0090] In summary, in the process of using the electrode assembly 10, the lithium ions in the positive electrode active material region 111 of each positive electrode plate 1 penetrate the diaphragm 3 and are embedded in the negative electrode active material region 211 of the adjacent negative electrode plate 2. Since both ends of the negative electrode active material region 211 along the winding axis K extend beyond the corresponding ends of the adjacent positive electrode active material region 111, the lithium ions are reliably embedded in the negative electrode active material region 211 as much as possible, the risk of lithium precipitation is reduced, and the positive electrode active material of the positive electrode active material region 111 can fully play its role.

[0091] In addition, when the electrode assembly 10 includes multiple positive electrode plates 1 or multiple negative electrode plates 2, the multiple positive electrode plates 1 or multiple negative electrode plates 2 are wound simultaneously, and therefore the winding efficiency of the electrode assembly 10 of this embodiment is obviously improved compared to the case where multiple positive electrode plates 1 are connected and then positive electrode plates 1 of the same length are wound or the case where multiple negative electrode plates 2 are connected and then negative electrode plates 2 of the same length are wound. For example, when one positive plate 1 and one negative plate 2 of length L are overlapped and wound, the winding length is L and the winding time is T, whereas in the embodiment of the present application, the positive plate 1 of length L is divided into a plurality of positive plates 1, and the negative plate 2 of length L is divided into M negative plates 2 (M is an integer of 2 or more), resulting in, for example, M positive plates 1 and M negative plates 2, whereas in the present embodiment, if other conditions (e.g., winding speed and diameter of the winding core) are not changed, the winding distance of the M positive plates 1 and the M negative plates 2 of the present embodiment is just L / M, and the winding time is T / M. Therefore, the number of winding turns of the electrode assembly 10 of the present embodiment is reduced, which can exponentially improve the winding efficiency of the electrode assembly 10 and meet the production requirements.

[0092] Furthermore, since the number of winding turns of the electrode assembly 10 is reduced, the winding error during overlapping along the winding axis K in the winding process can be reduced, and the extent to which the negative electrode active material region 211 exceeds the positive electrode active material region 111 can be more easily controlled. This allows the reserve size of the negative electrode active material region 211 to be reduced, and space can be reserved to increase the area of ​​the positive electrode active material region 111 and the area of ​​the negative electrode active material region 211, thereby reducing the cost and improving the energy density of the electrode assembly 10.

[0093] In addition, since the number of winding turns of the electrode assembly 10 is reduced, the winding tension applied to the electrode plate becomes more uniform. This makes it possible to reduce the degree of bending of the curved portion after the electrode plate is flattened, and to alleviate wrinkles and deformation of the electrode plate, improve the contact performance between the positive electrode plate 1 and the negative electrode plate 2, realize effective contact between the positive electrode plate 1 and the negative electrode plate 2, and further optimize the performance of the electrode assembly 10.

[0094] Furthermore, with regard to the electrode assembly 10, since the number of windings is reduced, the amount of displacement of the positive electrode tab portion 12 after winding can be reduced, and connection to the collector member 30 becomes easier.

[0095] Furthermore, with regard to the structure in which the tabs are cut off on the positive electrode plate 1 and the negative electrode plate 2, after winding, the multiple positive electrode tab portions 12 are arranged in a stacked manner, and the multiple negative electrode tab portions 22 are also arranged in a stacked manner, thereby reducing the amount of misalignment of the multiple layers of positive electrode tab portions 12 and the amount of misalignment of the multiple layers of negative electrode tab portions 22, ensuring the connection area between each layer of tabs and the collector member 30, and increasing the overcurrent capacity of the tabs.

[0096] The electrode assembly 10 may include at least two positive electrode plates 1 and at least two negative electrode plates 2, but for ease of explanation, the following embodiment will be described using two positive electrode plates 1 and two negative electrode plates 2 as an example.

[0097] The outer shape of the wound structure of the electrode assembly 10 may be a cylindrical shape, a flat shape, an elliptical shape, a cubic shape, a rectangular parallelepiped shape, or any other shape. However, for ease of explanation, the following description will be given taking the wound structures of the electrode assembly 10 as flat and cylindrical shapes, respectively.

[0098] 12 is a structural schematic diagram showing a flat electrode assembly in another embodiment of the present application perpendicular to the cross section of the winding axis K. The electrode assembly 120 includes a first negative electrode plate 1201, a second negative electrode plate 1202, a first positive electrode plate 1203, a second positive electrode plate 1204, and a number of diaphragms 1205. The first negative electrode plate 1201, the first positive electrode plate 1203, the second negative electrode plate 1202, and the second positive electrode plate 1204 are alternately stacked in order. The first negative electrode plate 1201 is separated from the first positive electrode plate 1203 by the diaphragm 1205, the first positive electrode plate 1203 is separated from the second negative electrode plate 1202 by another diaphragm 1205, and the second negative electrode plate 1202 is separated from the second positive electrode plate 1204 by another diaphragm 1205. The first negative electrode plate 1201, the second negative electrode plate 1202, the first positive electrode plate 1203, the second positive electrode plate 1204, and the multiple diaphragms 1205 are all stacked and then wound around a winding axis K to form a flat wound structure.

[0099] In the electrode assembly 120 of this embodiment, with regard to the structures and positions of the positive electrode tab portions of the first positive electrode plate 1203 and the second positive electrode plate 1204 and the negative electrode tab portions of the first negative electrode plate 1201 and the second negative electrode plate 1202, please refer to the relevant contents of the positive electrode tab portions and the negative electrode tab portions described in the above embodiments in Figures 6 to 11. The contents will not be repeated here.

[0100] In this embodiment, with regard to the following specific condition for different radial directions of the winding structure of the electrode assembly 120, that is, the difference in the number of layers of the electrode plates at different positions in the circumferential direction of the winding structure is not greater than a preset number of layers, please also refer to the related contents described in the above embodiment of Figures 6 to 11, which will not be repeated here.

[0101] With respect to the electrode assembly 120 of this embodiment, the negative electrode active material regions included in the first negative electrode plate 1201 and the second negative electrode plate 1202 may be the same as the negative electrode active material regions included in the negative electrode plates described in the above embodiments of Figures 6 to 11. Also, the positive electrode active material regions included in the first positive electrode plate 1203 and the second positive electrode plate 1204 may be the same as the positive electrode active material regions included in the positive electrode plates described in the above embodiments of Figures 6 to 11. These contents will not be repeated here.

[0102] In this embodiment, both ends of the negative electrode active material region of the first negative electrode plate 1201 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1203 along the winding axis K, and both ends of the negative electrode active material region of the second negative electrode plate 1202 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1203 and second positive electrode plate 1204 along the winding axis K. Also, for specific conditions, such as the size of the excess, for both ends of the negative electrode active material region of the first negative electrode plate 1201 and the second negative electrode plate 1202 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate, please refer to the contents of both ends of the negative electrode active material region of the negative electrode plate 2 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate described in the embodiment of Figs. 6 to 11 above. That content will not be repeated here.

[0103] In the wound structure, the innermost ring in the wound structure is the ring surrounded by the first negative plate 1201 and the outermost ring in the wound structure is the ring surrounded by the second negative plate 1202 .

[0104] In this embodiment, the winding structure of the electrode assembly 120 includes a flattened region 10A and a turn region 10B on both sides of the flattened region 10A. The overlapping surfaces of the electrode plates in the flattened region 10A are essentially parallel planes, and are essentially parallel to the winding axis, and the planes here are not strictly planes, and allow for some error. In a plane perpendicular to the winding axis K, the flattened region 10A includes a first small flattened region 10A1 and a second small flattened region 10A2, which are essentially parallel and symmetrically distributed with respect to the winding axis K. The two turn regions 10B are respectively arranged in the first small flattened region 10A1 and the second small flattened region 10A2, which are on both sides of the flattened region 10A.

[0105] The positions of the first winding start ends S of the first positive electrode plate 1203 and the second positive electrode plate 1204 are the same. For example, the first winding start ends S of the first positive electrode plate 1203 and the second positive electrode plate 1204 are both disposed in the small flattened region (e.g., the first small flattened region 10A1) on the same side of the flattened region 10A, and the first winding start ends S of the first positive electrode plate 1203 and the second positive electrode plate 1204 are on the same plane.

[0106] The positions of the second winding start ends S' of the first negative electrode plate 1201 and the second negative electrode plate 1202 are also the same. For example, the second winding start ends S' of the first negative electrode plate 1201 and the second negative electrode plate 1202 are both disposed in the small flattened region (for example, the first small flattened region 10A1) on the same side of the flattened region 10A, and the second winding start ends S' of the first negative electrode plate 1201 and the second negative electrode plate 1202 are on the same plane.

[0107] Along the reverse winding direction, the second winding start end S′ of the first negative electrode plate 1201 extends beyond the first winding start end S of the first positive electrode plate 1203. The second winding start end S′ of the second negative electrode plate 1202 extends beyond the first winding start end S of the second positive electrode plate 1204.

[0108] The positions of the first winding ends E of the first positive electrode plate 1203 and the second positive electrode plate 1204 are the same. For example, the first winding ends E of the first positive electrode plate 1203 and the second positive electrode plate 1204 are both disposed in the same side of the turning region (for example, the first turning region 10B1), and the first winding ends E of the first positive electrode plate 1203 and the second positive electrode plate 1204 are on the same plane.

[0109] The positions of the second winding ends E′ of the first negative electrode plate 1201 and the second negative electrode plate 1202 are also the same. For example, the second winding ends E′ of the first negative electrode plate 1201 and the second negative electrode plate 1202 are both arranged in a turning region on the same side (e.g., the first turning region 10B1) and are also arranged in a turning region on the same side (e.g., the first turning region 10B1) as the first winding ends E of the first positive electrode plate 1203 and the second positive electrode plate 1204, and the second winding ends E′ of the first negative electrode plate 1201 and the second negative electrode plate 1202 are on the same plane.

[0110] Along the winding direction, the second winding end E′ of the first negative plate 1201 extends beyond the first winding end E of the second positive plate 1204. The second winding end E′ of the second negative plate 1202 extends beyond the first winding end E of the first positive plate 1203.

[0111] The winding structure of the electrode assembly described above can make it possible to approximate the difference in length between the multiple electrode plates before winding, which makes winding easier.

[0112] 13 is a structural schematic diagram showing a flat electrode assembly in another embodiment of the present application perpendicular to the cross section of the winding axis K. The electrode assembly 130 includes a first negative electrode plate 1301, a second negative electrode plate 1302, a first positive electrode plate 1303, a second positive electrode plate 1304, and a number of diaphragms 1305. The first negative electrode plate 1301, the first positive electrode plate 1303, the second negative electrode plate 1302, and the second positive electrode plate 1304 are alternately stacked in order. The first negative plate 1301 is separated from the first positive plate 1303 by a diaphragm 1305, the first positive plate 1303 is separated from the second negative plate 1302 by another diaphragm 1305, and the second negative plate 1302 is separated from the second positive plate 1304 by another diaphragm 1305. The first negative plate 1301, the second negative plate 1302, the first positive plate 1303, the second positive plate 1304, and the multiple diaphragms 1305 are all stacked and then wound around a winding axis K to form a flat wound structure.

[0113] In this embodiment, both ends of the negative electrode active material region of the first negative electrode plate 1301 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1303 along the winding axis K, and both ends of the negative electrode active material region of the second negative electrode plate 1302 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1303 and second positive electrode plate 1304 along the winding axis K. Also, for specific conditions, such as the size of the excess, for both ends of the negative electrode active material region of the first negative electrode plate 1301 and the second negative electrode plate 1302 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate, please refer to the contents of both ends of the negative electrode active material region of the negative electrode plate 2 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate described in the above embodiment of Figures 6 to 11. That content will not be repeated here.

[0114] The structure of the electrode assembly 130 of this embodiment is basically similar to the structure of the electrode assembly described in the embodiment of FIG. 12, and differences will be described below.

[0115] In the winding structure of the electrode assembly 130 of this embodiment, the innermost ring in the winding structure is the ring surrounded by the first negative electrode plate 1301, and the outermost ring in the winding structure is the ring jointly surrounded by the first negative electrode plate 1301 and the second negative electrode plate 1302.

[0116] The first winding ends E of the first positive plate 1303 and the second positive plate 1304 are different. For example, the first winding ends E of the first positive plate 1303 and the second positive plate 1304 are disposed in the second winding region 10B2 and the first winding region 10B1, respectively.

[0117] The second winding ends E′ of the first negative electrode plate 1301 and the second negative electrode plate 1302 are also different. For example, the second winding ends E′ of the first negative electrode plate 1301 and the second negative electrode plate 1302 are disposed in the first winding region 10B1 and the second winding region 10B2, respectively.

[0118] Along the winding direction, the second winding end E′ of the first negative plate 1301 extends beyond the first winding end E of the second positive plate 1304. The second winding end E′ of the second negative plate 1302 extends beyond the first winding end E of the first positive plate 1303.

[0119] The winding structure of the electrode assembly described above can reduce the step formed by the first positive electrode plate 1303 and the second positive electrode plate 1304 at the first winding end E, and can also reduce the step formed by the first negative electrode plate 1301 and the second negative electrode plate 1302 at the second winding end E'. As a result, it is possible to reduce local stress applied to the electrode plates at the winding end after they come into contact with the housing when the electrode assembly expands, prevent cracks in the electrode plates or the active material from falling off, and improve the reliability of the long-term operation of the electrode assembly.

[0120] 14 is a structural schematic diagram showing a flat electrode assembly in another embodiment of the present application perpendicular to the cross section of the winding axis K. The electrode assembly 140 includes a first negative electrode plate 1401, a second negative electrode plate 1402, a first positive electrode plate 1403, a second positive electrode plate 1404, and a number of diaphragms 1405. The first positive electrode plate 1401, the first positive electrode plate 1403, the second negative electrode plate 1402, and the second positive electrode plate 1404 are alternately stacked in order. The first negative electrode plate 1401 is separated from the first positive electrode plate 1403 by a diaphragm 1405, the first positive electrode plate 1403 is separated from the second negative electrode plate 1402 by another diaphragm 1405, and the second negative electrode plate 1402 is separated from the second positive electrode plate 1404 by another diaphragm 1405. The first negative electrode plate 1401, the second negative electrode plate 1402, the first positive electrode plate 1403, the second positive electrode plate 1404, and the multiple diaphragms 1405 are all stacked and then wound around a winding axis K to form a flat wound structure.

[0121] In this embodiment, both ends of the negative electrode active material region of the first negative electrode plate 1401 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1403 along the winding axis K, and both ends of the negative electrode active material region of the second negative electrode plate 1402 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1403 and second positive electrode plate 1404 along the winding axis K, respectively. For specific conditions, such as the size of the excess, regarding both ends of the negative electrode active material region of the first negative electrode plate 1401 and the second negative electrode plate 1402 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate, please refer to the contents of both ends of the negative electrode active material region of the negative electrode plate 2 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate described in the above embodiment of Figures 6 to 11. That content will not be repeated here.

[0122] The structure of the electrode assembly 140 of this embodiment is basically similar to the structure of the electrode assembly described in the embodiment of FIG. 12, and differences will be described below.

[0123] In the winding structure of the electrode assembly 140 of this embodiment, the innermost ring in the winding structure is the ring surrounded by the first negative electrode plate 1401, and the outermost ring in the winding structure is the ring surrounded by the second negative electrode plate 1402.

[0124] In the winding structure of the electrode assembly of this embodiment, the positions of the second winding ends E′ of the first negative electrode plate 1401 and the second negative electrode plate 1402 are different. For example, the second winding ends E′ of the first negative electrode plate 1401 and the second negative electrode plate 1402 are respectively disposed in the same winding region (e.g., the first winding region 10B1), and the second winding ends E′ of the first negative electrode plate 1401 and the second negative electrode plate 1402 are not on the same plane.

[0125] The above-mentioned winding structure of the electrode assembly 140 can reduce the difference in the number of layers of the electrode plates between the first small flattened area 10A1 and the second small flattened area 10A2. When the electrode assembly expands and contacts the housing, and the inner wall of the housing exerts a reaction force on both sides of the electrode assembly, the stresses on the electrode plates of the first small flattened area 10A1 and the second small flattened area 10A2 are the same.

[0126] 15 is a structural schematic diagram showing a flat electrode assembly in another embodiment of the present application perpendicular to the cross section of the winding axis K. The electrode assembly 150 includes a first negative electrode plate 1501, a second negative electrode plate 1502, a first positive electrode plate 1503, a second positive electrode plate 1504, and a number of diaphragms 1505. The first negative electrode plate 1501, the first positive electrode plate 1503, the second negative electrode plate 1502, and the second positive electrode plate 1504 are alternately stacked in order. The first negative plate 1501 is separated from the first positive plate 1503 by a diaphragm 1505, the first positive plate 1503 is separated from the second negative plate 1502 by another diaphragm 1505, and the second negative plate 1502 is separated from the second positive plate 1504 by another diaphragm 1505. The first negative plate 1501, the second negative plate 1502, the first positive plate 1503, the second positive plate 1504, and the multiple diaphragms 1505 are all stacked and then wound around a winding axis K to form a flat wound structure.

[0127] In this embodiment, both ends of the negative electrode active material region of the first negative electrode plate 1501 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1503 along the winding axis K, and both ends of the negative electrode active material region of the second negative electrode plate 1502 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1503 and second positive electrode plate 1504 along the winding axis K. Also, for specific conditions, such as the size of the excess, regarding both ends of the negative electrode active material region of the first negative electrode plate 1501 and the second negative electrode plate 1502 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate, please refer to the contents of both ends of the negative electrode active material region of the negative electrode plate 2 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate described in the above embodiment of Figures 6 to 11. That content will not be repeated here.

[0128] The structure of the electrode assembly 150 of this embodiment is basically the same as the structure of the electrode assembly described in the embodiment of Fig. 12, and the differences will be described below. In the wound structure of the electrode assembly of this embodiment, the innermost ring in the wound structure is a ring surrounded by the first negative electrode plate 1501 and the second negative electrode plate 1502 together, and the outermost ring in the wound structure is a ring surrounded by the second negative electrode plate 1502.

[0129] In the winding structure of the electrode assembly 150 of this embodiment, the positions of the first winding start ends S of the first positive electrode plate 1503 and the second positive electrode plate 1504 are different. For example, the first winding start ends S of the first positive electrode plate 1503 and the second positive electrode plate 1504 are disposed in the first small flattened region 10A1 and the second small flattened region 10A2, respectively, and the first winding start ends S of the first positive electrode plate 1503 and the second positive electrode plate 1504 are not on the same plane.

[0130] The positions of the second winding start ends S of the first negative electrode plate 1501 and the second negative electrode plate 1502 are also different. For example, the second winding start ends S of the first negative electrode plate 1501 and the second negative electrode plate 1502 are disposed in the first small flattened region 10A1 and the second small flattened region 10A2, respectively, and the second winding start ends S of the first negative electrode plate 1501 and the second negative electrode plate 1502 are not on the same plane.

[0131] The winding structure of the electrode assembly described above can reduce the step formed by the first positive electrode plate 1503 and the second positive electrode plate 1504 at the first winding start end S, and can also reduce the step formed by the first negative electrode plate 1501 and the second negative electrode plate 1502 at the second winding start end S'. As a result, it is possible to reduce local stress applied to the electrode plates at the winding start end after the electrode assembly expands and comes into contact with the housing 20, prevent cracks in the electrode plates or the active material from falling off, and improve the reliability of long-term operation of the electrode assembly.

[0132] 16 is a structural schematic diagram showing a flat electrode assembly in another embodiment of the present application perpendicular to the cross section of the winding axis K. The electrode assembly 160 includes a first negative electrode plate 1601, a second negative electrode plate 1602, a first positive electrode plate 1603, a second positive electrode plate 1604, and a number of diaphragms 1605. The first negative electrode plate 1601, the first positive electrode plate 1603, the second positive electrode plate 1602, and the second positive electrode plate 1604 are alternately stacked in order. The first negative plate 1601 is separated from the first positive plate 1603 by a diaphragm 1605, the first positive plate 1603 is separated from the second negative plate 1602 by another diaphragm 1605, and the second negative plate 1602 is separated from the second positive plate 1604 by another diaphragm 1605. The first negative plate 1601, the second negative plate 1602, the first positive plate 1603, the second positive plate 1604, and the multiple diaphragms 1605 are all stacked and then wound around a winding axis K to form a flat wound structure.

[0133] In this embodiment, both ends of the negative electrode active material region of the first negative electrode plate 1601 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1603 along the winding axis K, and both ends of the negative electrode active material region of the second negative electrode plate 1602 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1603 and second positive electrode plate 1604 along the winding axis K. Also, for specific conditions, such as the size of the excess, for both ends of the negative electrode active material region of the first negative electrode plate 1601 and the second negative electrode plate 1602 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate, please refer to the contents of both ends of the negative electrode active material region of the negative electrode plate 2 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate described in the above embodiment of Figures 6 to 11. That content will not be repeated here.

[0134] The structure of the electrode assembly 160 of this embodiment is basically the same as the structure of the electrode assembly described in the embodiment of Fig. 12, and the differences will be described below. In the wound structure of the electrode assembly of this embodiment, the innermost ring in the wound structure is a ring surrounded by the first negative electrode plate 1601 and the second negative electrode plate 1602 together, and the outermost ring in the wound structure is a ring surrounded by the first negative electrode plate 1601 and the second negative electrode plate 1602 together.

[0135] In the winding structure of the electrode assembly 160 of this embodiment, the positions of the first winding start ends S of the first positive electrode plate 1603 and the second positive electrode plate 1604 are different. For example, the first winding start ends S of the first positive electrode plate 1603 and the second positive electrode plate 1604 are disposed in the first small flattened area 10A1 and the second small flattened area 10A2, respectively, and the first winding start ends S of the first positive electrode plate 1603 and the second positive electrode plate 1604 are not on the same plane.

[0136] The positions of the second winding start ends S' of the first negative electrode plate 1601 and the second negative electrode plate 1602 are also different. For example, the second winding start ends S' of the first negative electrode plate 1601 and the second negative electrode plate 1602 are disposed in the first small flattened region 10A1 and the second small flattened region 10A2, respectively, and the second winding start ends S' of the first negative electrode plate 1601 and the second negative electrode plate 1602 are not on the same plane.

[0137] The positions of the first winding ends E of the first positive electrode plate 1603 and the second positive electrode plate 1604 are different. For example, the first winding ends E of the first positive electrode plate 1603 and the second positive electrode plate 1604 are disposed in different turning regions 10B, and the first winding ends E of the first positive electrode plate 1603 and the second positive electrode plate 1604 are not on the same plane.

[0138] The positions of the second winding ends E′ of the first negative electrode plate 1601 and the second negative electrode plate 1602 are also different. For example, the second winding ends E′ of the first negative electrode plate 1601 and the second negative electrode plate 1602 are disposed in two different turning regions 10B, respectively, and the second winding ends E′ of the first negative electrode plate 1601 and the second negative electrode plate 1602 are not on the same plane.

[0139] The winding structure of the electrode assembly described above can simultaneously reduce the step formed by the first positive electrode plate 1603 and the second positive electrode plate 1604 at the first winding start end S and the first winding end E, and simultaneously reduce the step formed by the first negative electrode plate 1601 and the second negative electrode plate 1602 at the second winding start end S' and the second winding end E'. As a result, it is possible to reduce local stress applied to the electrode plates at the winding start end and the winding end after the electrode assembly expands and comes into contact with the housing 20, prevent cracks in the electrode plates or the active material from falling off, and improve the reliability of long-term operation of the electrode assembly.

[0140] Based on the above embodiment, the difference in the number of layers of the electrode plates at different radial positions of the winding structure, i.e., different circumferential positions of the winding structure, does not exceed a preset number of layers. Here, the number of layers of the electrode plates refers to the total number of layers of the positive electrode plates and the negative electrode plates. Also, the preset number of layers is equal to or less than the total number of the multiple positive electrode plates and the multiple negative electrode plates.

[0141] When the electrode assembly expands and comes into contact with the housing 20, the housing 20 exerts a reaction force on the electrode assembly, so that the stress on each point in the circumferential direction of the electrode assembly becomes more uniform. This prevents the electrode assembly from having large performance differences at individual points during the use process. For example, two positive electrode plates are arranged, two negative electrode plates are arranged, and the preset number of layers is 4 or less, and the smaller the difference in the number of layers of the electrode plates, the more uniform the stress on the electrode assembly at each point in the circumferential direction.

[0142] As shown in Figs. 13 to 16, the outermost layer and the innermost layer of the winding structure are both negative electrode plates. The material of the positive electrode active material in the positive electrode plate is usually a ternary material, lithium manganese oxide, or lithium iron phosphate, and the material of the negative electrode active material in the negative electrode plate is usually graphite or silicon. Since the material of the positive electrode active material is more expensive than the material of the negative electrode active material, the outermost layer and the innermost layer of the winding structure are coated by the negative electrode plate, so that the positive electrode active material of the positive electrode plate can be fully utilized. This not only improves the energy utilization rate of the winding structure, but also reduces the difficulty of the manufacturing process of the electrode assembly.

[0143] Optionally, a positive electrode plate is employed in at least one of the outermost layer and the innermost layer of the winding structure, and in order to reduce the manufacturing cost of the electrode assembly, for the positive electrode plate disposed in the outermost layer or the innermost layer, it is not necessary to coat the positive electrode active material on the surface of the positive electrode plate that is away from the negative electrode plate.

[0144] 17 to 20 are schematic structural diagrams of a cylindrical electrode assembly.

[0145] 17 is a structural schematic diagram showing a cylindrical electrode assembly perpendicular to the cross section of the winding axis K in another embodiment of the present application. The electrode assembly 170 includes a first negative electrode plate 1701, a second negative electrode plate 1702, a first positive electrode plate 1703, a second positive electrode plate 1704, and a number of diaphragms 1705. The first negative electrode plate 1701, the first positive electrode plate 1703, the second negative electrode plate 1702, and the second positive electrode plate 1704 are alternately stacked in order. The first negative electrode plate 1701 is separated from the first positive electrode plate 1703 by a diaphragm 1705, the first positive electrode plate 1703 is separated from the second negative electrode plate 1702 by another diaphragm 1705, and the second negative electrode plate 1702 is separated from the second positive electrode plate 1704 by another diaphragm 1705. The first negative electrode plate 1701, the second negative electrode plate 1702, the first positive electrode plate 1703, the second positive electrode plate 1704, and the multiple diaphragms 1705 are all stacked and then wound around a winding axis K to form a cylindrical wound structure.

[0146] In the electrode assembly 170 of this embodiment, with regard to the structures and positions of the positive electrode tab portions of the first positive electrode plate 1703 and the second positive electrode plate 1704 and the negative electrode tab portions of the first negative electrode plate 1701 and the second negative electrode plate 1702, please refer to the relevant contents of the positive electrode tab portions and the negative electrode tab portions described in the above embodiment in Figures 6 to 11. The contents will not be repeated here.

[0147] In this embodiment, with regard to the following specific condition for different radial directions of the winding structure, i.e., the difference in the number of layers of the electrode plates at different circumferential positions of the winding structure is not greater than a preset number of layers, please also refer to the related contents described in the above embodiment of Figures 6 to 11, which will not be repeated here.

[0148] With respect to the electrode assembly 170 of this embodiment, the negative electrode active material regions included in the first negative electrode plate 1701 and the second negative electrode plate 1702 may be the same as the negative electrode active material regions included in the negative electrode plates described in the above embodiments of Figures 6 to 11. Also, the positive electrode active material regions included in the first positive electrode plate 1703 and the second positive electrode plate 1704 may be the same as the positive electrode active material regions included in the positive electrode plates described in the above embodiments of Figures 6 to 11. These contents will not be repeated here.

[0149] In this embodiment, both ends of the negative electrode active material region of the first negative electrode plate 1701 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1703 along the winding axis K, and both ends of the negative electrode active material region of the second negative electrode plate 1702 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1703 and second positive electrode plate 1704 along the winding axis K. Also, for specific conditions, such as the size of the excess, regarding both ends of the negative electrode active material region of the first negative electrode plate 1701 and the second negative electrode plate 1702 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate, please refer to the contents of both ends of the negative electrode active material region of the negative electrode plate along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate described in the above embodiment of Figures 6 to 11. That content will not be repeated here.

[0150] In the wound structure, the innermost ring in the wound structure is the ring surrounded by the first negative plate 1701 and the outermost ring in the wound structure is the ring surrounded by the second negative plate 1702 .

[0151] The positions of the first winding start ends S of the first positive electrode plate 1703 and the second positive electrode plate 1704 are the same. For example, the first winding start ends S of the first positive electrode plate 1703 and the second positive electrode plate 1704 are both disposed in the same radial direction of the winding structure, and the first winding start ends S of the first positive electrode plate 1703 and the second positive electrode plate 1704 are on the same plane.

[0152] The positions of the second winding start ends S' of the first negative electrode plate 1701 and the second negative electrode plate 1702 are also the same. For example, the second winding start ends S' of the first negative electrode plate 1701 and the second negative electrode plate 1702 are both disposed in the same radial direction of the winding structure, and the second winding start ends S' of the first negative electrode plate 1701 and the second negative electrode plate 1702 are on the same plane.

[0153] Along the reverse winding direction, the second winding start end S′ of the first negative electrode plate 1701 extends beyond the first winding start end S of the first positive electrode plate 1704. The second winding start end S′ of the second negative electrode plate 1702 extends beyond the first winding start end S of the second positive electrode plate 1703.

[0154] The positions of the first winding ends E of the first positive electrode plate 1703 and the second positive electrode plate 1704 are the same. For example, the first winding ends E of the first positive electrode plate 1703 and the second positive electrode plate 1704 are both disposed in the same side of the turning region 10B, and the first winding ends E of the first positive electrode plate 1703 and the second positive electrode plate 1704 are on the same plane.

[0155] The positions of the second winding ends E′ of the first negative electrode plate 1701 and the second negative electrode plate 1702 are also the same. For example, the second winding ends E′ of the first negative electrode plate 1701 and the second negative electrode plate 1702 are both disposed in the same turning region 10B, and the second winding ends E′ of the first negative electrode plate 1701 and the second negative electrode plate 1702 are on the same plane.

[0156] Along the winding direction, the second winding end E′ of the first negative plate 1701 extends beyond the first winding end E of the second positive plate 1704. The second winding end E′ of the second negative plate 1702 extends beyond the first winding end E of the first positive plate 1703.

[0157] The winding structure described above can make it possible to approximate the difference in length between the multiple electrode plates before winding, which makes winding easier.

[0158] 18 is a structural schematic diagram showing a cylindrical electrode assembly perpendicular to the cross section of the winding axis K in another embodiment of the present application. The electrode assembly 180 includes a first negative electrode plate 1801, a second negative electrode plate 1802, a first positive electrode plate 1803, a second positive electrode plate 1804, and a number of diaphragms 1805. The first negative electrode plate 1801, the first positive electrode plate 1803, the second negative electrode plate 1802, and the second positive electrode plate 1804 are alternately stacked in order. The first negative electrode plate 1801 is separated from the first positive electrode plate 1803 by a diaphragm 1805, the first positive electrode plate 1803 is separated from the second negative electrode plate 1802 by another diaphragm 1805, and the second negative electrode plate 1802 is separated from the second positive electrode plate 1804 by another diaphragm 1805. The first negative electrode plate 1801, the second negative electrode plate 1802, the first positive electrode plate 1803, the second positive electrode plate 1804, and the multiple diaphragms 1805 are all stacked and then wound around a winding axis K to form a cylindrical wound structure.

[0159] In this embodiment, both ends of the negative electrode active material region of the first negative electrode plate 1801 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1803 along the winding axis K, and both ends of the negative electrode active material region of the second negative electrode plate 1802 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1803 and second positive electrode plate 1804 along the winding axis K. Also, for specific conditions, such as the size of the excess, for both ends of the negative electrode active material region of the first negative electrode plate 1801 and the second negative electrode plate 1802 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate, please refer to the contents of both ends of the negative electrode active material region of the negative electrode plate 2 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate 1 described in the above embodiment of Figures 6 to 11. That content will not be repeated here.

[0160] The structure of this embodiment is basically the same as the structure described in the embodiment of Fig. 17, and the differences will be described below. In the winding structure of this embodiment, the innermost ring of the winding structure is a ring surrounded by the first negative electrode plate 1801 and the second negative electrode plate 1802 together, and the outermost ring of the winding structure is a ring surrounded by the first negative electrode plate 1801.

[0161] In the winding structure of this embodiment, the positions of the first winding start ends S of the first positive electrode plate 1803 and the second positive electrode plate 1804 are different. For example, the first winding start ends S of the first positive electrode plate 1803 and the second positive electrode plate 1804 are disposed in the relative radial direction of the winding structure, and the first winding start ends S of the first positive electrode plate 1803 and the second positive electrode plate 1804 are not on the same plane.

[0162] The positions of the second winding start S' of the first negative electrode plate 1801 and the second negative electrode plate 1802 are also different. For example, the second winding start S' of the first negative electrode plate 1801 and the second winding start S' of the second negative electrode plate 1802 are disposed in the relative radial direction of the winding structure, and the second winding start S' of the first negative electrode plate 1801 and the second negative electrode plate 1802 are not on the same plane.

[0163] The above-described winding structure can reduce the step formed by the first positive electrode plate 1803 and the second positive electrode plate 1804 at the first winding start end S, and can also reduce the step formed by the first negative electrode plate 1801 and the second negative electrode plate 1802 at the second winding start end S'. As a result, it is possible to reduce local stress applied to the electrode plates at the winding start end after the electrode assembly expands and comes into contact with the housing 20, prevent cracks in the electrode plates or the active material from falling off, and improve the reliability of long-term operation of the electrode assembly.

[0164] 19 is a structural schematic diagram showing a cylindrical electrode assembly perpendicular to the cross section of the winding axis K in another embodiment of the present application. The electrode assembly 190 includes a first negative electrode plate 1901, a second negative electrode plate 1902, a first positive electrode plate 1903, a second positive electrode plate 1904, and a number of diaphragms 1905. The first negative electrode plate 1901, the first positive electrode plate 1903, the second negative electrode plate 1902, and the second positive electrode plate 1904 are alternately stacked in order. The first negative electrode plate 1901 is separated from the first positive electrode plate 1903 by a diaphragm 1905, the first positive electrode plate 1903 is separated from the second negative electrode plate 1902 by another diaphragm 1905, and the second negative electrode plate 1902 is separated from the second positive electrode plate 1904 by another diaphragm 1905. The first negative electrode plate 1901, the second negative electrode plate 1902, the first positive electrode plate 1903, the second positive electrode plate 1904, and the multiple diaphragms 1905 are all stacked and then wound around a winding axis K to form a cylindrical wound structure.

[0165] In this embodiment, both ends of the negative electrode active material region of the first negative electrode plate 1901 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1903 along the winding axis K, and both ends of the negative electrode active material region of the second negative electrode plate 1902 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 1903 and second positive electrode plate 1904 along the winding axis K, respectively. For specific conditions, such as the size of the excess, regarding both ends of the negative electrode active material region of the first negative electrode plate 1901 and the second negative electrode plate 1902 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate, please refer to the contents of both ends of the negative electrode active material region of the negative electrode plate 2 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate 1 described in the above embodiment of Figures 6 to 11. That content will not be repeated here.

[0166] The structure of this embodiment is basically the same as the configuration described in the embodiment of Fig. 18, and the differences will be described below. In the winding structure of this embodiment, the innermost ring of the winding structure is a ring surrounded by the first negative electrode plate 1901 and the second negative electrode plate 1902 together, and the outermost ring of the winding structure is a ring surrounded by the first negative electrode plate 1901.

[0167] In the winding structure of this embodiment, the positions of the first winding ends E of the first positive electrode plate 1903 and the second positive electrode plate 1904 are different. Also, the positions of the second winding ends E′ of the first negative electrode plate 1901 and the second negative electrode plate 1902 are different.

[0168] Along the winding direction, the first negative electrode plate 1901 is disposed in the outermost layer, and the end position of the second winding end E′ exceeds the end position of the second winding end E′ of the second negative electrode plate 1902, and the end position of the first winding end E of the first positive electrode plate 1903 exceeds the end position of the first winding end E of the second positive electrode plate 1904, for example, by half a ring. The exceeding portion is pushed inward along the radial direction until it contacts the electrode plate of the inner layer, improving the stability of the winding structure.

[0169] The above-described winding structure can simultaneously reduce the step formed by the first positive electrode plate 1903 and the second positive electrode plate 1904 at the first winding start end S and the first winding end E, and simultaneously reduce the step formed by the first negative electrode plate 1901 and the second negative electrode plate 1902 at the second winding start end S' and the second winding end E'. As a result, it is possible to reduce local stress applied to the electrode plates at the winding start end and the winding end after the electrode assembly expands and comes into contact with the housing 20, prevent cracks in the electrode plates or the active material from falling off, and improve the reliability of long-term operation of the electrode assembly.

[0170] Furthermore, the number of layers of the winding structure in different radial directions may be the same, but for a cylindrical winding structure, the stresses at each point along the circumference will be consistent as the electrode assembly expands into contact with the housing 20.

[0171] 20 is a structural schematic diagram showing a cylindrical electrode assembly in another embodiment of the present application perpendicular to the cross section of the winding axis K. The electrode assembly 200 includes a first negative electrode plate 2001, a second negative electrode plate 2002, a first positive electrode plate 2003, a second positive electrode plate 2004, and a number of diaphragms 2005. The first negative electrode plate 2001, the first positive electrode plate 2003, the second negative electrode plate 2002, and the second positive electrode plate 2004 are alternately stacked in order. The first negative electrode plate 2001 is separated from the first positive electrode plate 2003 by a diaphragm 2005, the first positive electrode plate 2003 is separated from the second negative electrode plate 2002 by another diaphragm 2005, and the second negative electrode plate 2002 is separated from the second positive electrode plate 2004 by another diaphragm 2005. The first negative electrode plate 2001, the second negative electrode plate 2002, the first positive electrode plate 2003, the second positive electrode plate 2004, and the multiple diaphragms 2005 are all stacked and then wound around a winding axis K to form a cylindrical wound structure.

[0172] In this embodiment, both ends of the negative electrode active material region of the first negative electrode plate 2001 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 2003 along the winding axis K, and both ends of the negative electrode active material region of the second negative electrode plate 2002 along the winding axis K exceed the corresponding ends of the positive electrode active material covered region of the adjacent first positive electrode plate 2003 and second positive electrode plate 2004 along the winding axis K. Also, for specific conditions, such as the size of the excess, for both ends of the negative electrode active material region of the first negative electrode plate 2001 and the second negative electrode plate 2002 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate, please refer to the contents of both ends of the negative electrode active material region of the negative electrode plate 2 along the winding axis K and the corresponding ends of the positive electrode active material region of the adjacent positive electrode plate 1 described in the above embodiment of Figures 6 to 11. That content will not be repeated here.

[0173] The structure of this embodiment is basically the same as the structure described in the embodiment of Fig. 18, and the differences will be described below. In the winding structure of this embodiment, the innermost ring in the winding structure is a ring surrounded by the first negative electrode plate 2001 and the second negative electrode plate 2002 together, and the outermost ring in the winding structure is a ring surrounded by the first negative electrode plate 2001 and the second negative electrode plate 2002 together.

[0174] Along the winding direction, the second negative plate 2002 is arranged in the outermost layer, and the end position of the second winding end E' exceeds the end position of the second winding end E' of the first negative plate 2001, and the end position of the first winding end E of the second positive plate 2004 exceeds the end position of the first winding end E of the first positive plate 2003, for example, by half a ring.

[0175] The above-described winding structure can simultaneously reduce the step formed by the first positive electrode plate 2003 and the second positive electrode plate 2004 at the first winding start end S and the first winding end E, and simultaneously reduce the step formed by the first negative electrode plate 2001 and the second negative electrode plate 2002 at the second winding start end S' and the second winding end E'. As a result, it is possible to reduce local stress applied to the electrode plates at the winding start end and the winding end after the electrode assembly expands and comes into contact with the housing 20, prevent cracks in the electrode plates or the active material from falling off, and improve the reliability of long-term operation of the electrode assembly.

[0176] Furthermore, the number of layers of the winding structure in different radial directions may be the same, but for a cylindrical winding structure, the stresses at each point along the circumference will be consistent as the electrode assembly expands into contact with the housing 20.

[0177] This structure also prevents the outermost layer of the electrode plate and the penultimate layer of the electrode plate from bending at the winding end of another electrode plate. As a result, all layers of the electrode plate are in contact with each other reliably, and local stress is less likely to occur in the electrode plate. This prevents the electrode plate from cracking or the active material from falling off.

[0178] Second, the present application further provides a method for manufacturing an electrode assembly. In some embodiments, the flow diagram shown in FIG.

[0179] Step 101 provides at least one positive plate 1 and at least one negative plate 2, where the total number of all positive plates 1 and all negative plates 2 is 3 or greater.

[0180] Step 102, at least one positive electrode plate 1 and at least one negative electrode plate 2 are wound around a winding axis K to form a wound structure.

[0181] Here, in this winding structure, the positive electrode plate 1 in at least one positive electrode plate 1 and the negative electrode plate 2 in at least one negative electrode plate 2 are arranged to overlap along a direction perpendicular to the winding axis K. Each positive electrode plate 1 in at least one positive electrode plate 1 includes a positive electrode main body portion 11, and at least a part of the overlapping surface area of ​​the positive electrode main body portion 11 is a positive electrode active material region 111, and each negative electrode plate 2 in at least one negative electrode plate 2 includes a negative electrode main body portion 21, and at least a part of the overlapping surface area of ​​the negative electrode main body portion 21 is a negative electrode active material region 211, and both ends of the negative electrode active material region 211 along the winding axis K exceed the corresponding ends of the adjacent positive electrode active material region 111.

[0182] Here, step 102 is performed after step 101. In step 101, specifically, a plurality of positive electrode plates 1, a plurality of diaphragms 3, and a plurality of negative electrode plates 2 are stacked in the thickness direction of the electrode plates, the plurality of positive electrode plates 1 and the plurality of negative electrode plates 2 are alternately arranged one by one, and the diaphragms 3 are arranged between the adjacent positive electrode plates 1 and negative electrode plates 2.

[0183] In this embodiment, by setting a plurality of positive electrode plates 1 and a plurality of negative electrode plates 2, the number of winding turns of the electrode assembly 10 can be reduced, the winding error in the winding process can be reduced, and the size by which the negative electrode active material region 211 exceeds the positive electrode active material region 111 can be more easily controlled. This allows the reserve size of the negative electrode active material region 211 to be reduced, and a space can be secured for increasing the area of ​​the positive electrode active material region 111 and the area of ​​the negative electrode active material region 211, so that the energy density of the electrode assembly 10 can be improved.

[0184] Finally, the present application further provides an electrode assembly manufacturing apparatus 500. In some embodiments, as shown in FIG.

[0185] The electrode plate arrangement mechanism 501 is configured to provide at least one positive electrode plate 1 and at least one negative electrode plate 2, where the total number of all positive electrode plates 1 and all negative electrode plates 2 is greater than or equal to three.

[0186] The winding mechanism 502 is configured to wind at least one positive electrode plate 1 and at least one negative electrode plate 2 around a winding axis K to form a winding structure.

[0187] Here, in the winding structure, the positive electrode plate 1 in at least one positive electrode plate 1 and the negative electrode plate 2 in at least one negative electrode plate 2 are alternately arranged along a direction perpendicular to the winding axis K. Each positive electrode plate 1 includes a positive electrode main body portion 11, and at least a part of the region of the positive electrode main body portion 11 along the winding axis K is a positive electrode active material region 111, and each negative electrode plate 2 includes a negative electrode main body portion 21, and at least a part of the region of the negative electrode main body portion 21 along the winding axis K is a negative electrode active material region 211, and both ends of the negative electrode active material region 211 along the winding axis K exceed the corresponding ends of the adjacent positive electrode active material region 111. The winding mechanism 502 can provide a stable winding tension to the overlapped electrode plates.

[0188] The electrode assembly 10 manufactured by the manufacturing apparatus 500 can reduce winding errors in the winding process and can easily control the size by which the negative electrode active material region 211 exceeds the positive electrode active material region 111. This reduces the spare size of the negative electrode active material region 211 and ensures space for increasing the areas of the positive electrode active material region 111 and the negative electrode active material region 211, thereby further improving the energy density of the electrode assembly 10.

[0189] Finally, it should be noted that the above embodiments are not intended to limit the present application, but are merely intended to describe the technical solutions of the present application. Although the present application has been described in detail with reference to the above embodiments, it should be understood that those skilled in the art may further modify the technical solutions recorded in each of the above embodiments, or equally replace some of the technical features (provided that all modifications or replacements ensure that the essence of the corresponding technical solutions does not depart from the spirit and scope of the technical solutions of each of the embodiments of the present application).

Claims

1. a battery having at least one positive electrode plate and at least one negative electrode plate, the total number of all positive electrode plates and all negative electrode plates being 3 or more, the at least one positive electrode plate and the at least one negative electrode plate being wound around a winding axis to form a winding structure, in which the positive electrode plate of the at least one positive electrode plate and the negative electrode plate of the at least one negative electrode plate are arranged to overlap each other along a direction perpendicular to the winding axis, each positive electrode plate in the at least one positive electrode plate has a positive electrode main body portion, at least a part of an area of ​​an overlapping surface of the positive electrode main body portion is a positive electrode active material region, and each negative electrode plate in the at least one negative electrode plate has a negative electrode main body portion, at least a part of an area of ​​an overlapping surface of the negative electrode main body portion is a negative electrode active material region, and both ends of the negative electrode active material region along the winding axis extend beyond corresponding ends of the adjacent positive electrode active material region; When the number of the at least one positive electrode plate is two or more, the positions of the first winding start ends of the at least two positive electrode plates are staggered in the circumferential direction of the winding structure, and / or when the number of the at least one negative electrode plate is two or more, the positions of the second winding start ends of the at least two negative electrode plates are staggered in the circumferential direction of the winding structure. Electrode assembly.

2. Both ends of the negative electrode active material region along the winding axis extend beyond the corresponding ends of the adjacent positive electrode active material region by 0.2 mm to 5 mm. The electrode assembly of claim 1 .

3. the positive electrode plate further has at least one positive electrode tab portion extending outward from the positive electrode main body portion along the direction of the winding axis, and the negative electrode plate further has at least one negative electrode tab portion extending outward from the negative electrode main body portion along the direction of the winding axis. The electrode assembly of claim 1 .

4. a part of a region of the positive electrode main body portion is a first insulating layer covered region, the first insulating layer covered region is disposed on a side of the positive electrode active material region adjacent to the positive electrode tab portion, and a first end of the negative electrode main body portion adjacent to the negative electrode tab portion along the direction of the winding axis is disposed in the first insulating layer covered region; 4. The electrode assembly of claim 3.

5. the negative electrode active material region covers the entire overlapping surface of the negative electrode main body portion along the winding axis, and a second end of the negative electrode main body portion away from the negative electrode tab portion along the winding axis direction exceeds the positive electrode active material region.

4. The electrode assembly of claim 3.

6. When the number of the at least one positive plate is two or more, the positions of the first winding ends of the at least two positive plates are staggered in the circumferential direction of the winding structure, and / or when the number of the at least one negative plate is two or more, the positions of the second winding ends of the at least two negative plates are staggered in the circumferential direction of the winding structure. An electrode assembly according to any one of claims 1 to 5.

7. the winding structure is flattened and has a flattened region and a turn region disposed on either side of the flattened region; A first winding end of the at least one positive plate is disposed in the turning region, and / or a second winding end of the at least one negative plate is disposed in the turning region. An electrode assembly according to any one of claims 1 to 5.

8. The difference in the number of layers of the electrode plates in different radial directions of the winding structure does not exceed a predetermined number of layers; An electrode assembly according to any one of claims 1 to 5.

9. The number of the preset layers is equal to or less than the total number of all positive plates and all negative plates; 9. The electrode assembly of claim 8.

10. The outermost layer and the innermost layer of the winding structure are all negative electrode plates. An electrode assembly according to any one of claims 1 to 9.

11. Housing and and an electrode assembly according to any one of claims 1 to 10, The electrode assembly is disposed within the housing. battery.

12. A battery module comprising a plurality of batteries according to claim 11.

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

14. A device that uses a battery, 12. The battery of claim 11, wherein the battery is configured to provide electrical energy to the device. device.

15. 1. A method for manufacturing an electrode assembly, comprising: providing at least one positive plate and at least one negative plate, wherein the total number of all positive plates and all negative plates is three or greater; and winding the at least one positive electrode plate and the at least one negative electrode plate around a winding shaft to form a winding structure, In the winding structure, a positive electrode plate in the at least one positive electrode plate and a negative electrode plate in the at least one negative electrode plate are arranged in a superimposed manner along a direction perpendicular to the winding axis, each positive electrode plate in the at least one positive electrode plate has a positive electrode main body portion, at least a part of an area of ​​an overlapping surface of the positive electrode main body portion is a positive electrode active material region, and each negative electrode plate in the at least one negative electrode plate has a negative electrode main body portion, at least a part of an area of ​​an overlapping surface of the negative electrode main body portion is a negative electrode active material region, and both ends of the negative electrode active material region along the winding axis extend beyond corresponding ends of the adjacent positive electrode active material region; When the number of the at least one positive electrode plate is two or more, the positions of the first winding start ends of the at least two positive electrode plates are staggered in the circumferential direction of the winding structure, and / or when the number of the at least one negative electrode plate is two or more, the positions of the second winding start ends of the at least two negative electrode plates are staggered in the circumferential direction of the winding structure. Manufacturing method.

16. An apparatus for manufacturing an electrode assembly, comprising: an electrode plate arrangement mechanism configured to provide at least one positive plate and at least one negative plate, wherein a total number of all positive plates and all negative plates is three or greater; a winding mechanism configured to wind the at least one positive electrode plate and the at least one negative electrode plate around a winding shaft to form a winding structure; In the winding structure, one positive electrode plate of the plurality of positive electrode plates and one negative electrode plate of the plurality of negative electrode plates are alternately arranged along a direction perpendicular to the winding axis, each positive electrode plate has a positive electrode main body portion, and at least a part of a region of the positive electrode main body portion along the winding axis is a positive electrode active material region, and each negative electrode plate has a negative electrode main body portion, and at least a part of a region of the negative electrode main body portion along the winding axis is a negative electrode active material region, and both ends of the negative electrode active material region along the winding axis extend beyond corresponding ends of the adjacent positive electrode active material region, When the number of the at least one positive electrode plate is two or more, the positions of the first winding start ends of the at least two positive electrode plates are staggered in the circumferential direction of the winding structure, and / or when the number of the at least one negative electrode plate is two or more, the positions of the second winding start ends of the at least two negative electrode plates are staggered in the circumferential direction of the winding structure. Manufacturing equipment.

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