Electrode assembly, battery cell, battery and electric device

Abstract

The invention is applicable to the field of batteries, and provides an electrode assembly, a battery monomer, a battery and a power utilization device, the electrode assembly comprises a first pole piece and a diaphragm, the diaphragm comprises two diaphragm layers formed by folding, and the two diaphragm layers respectively cover two opposite ends of the first pole piece along the thickness direction; each diaphragm layer is provided with a first edge part exceeding the end part of the first pole piece along the width direction of the first pole piece, the first edge parts are opposite to the folding ends of the diaphragms, and the first edge parts of the two diaphragm layers are connected with each other to form a first joint part. According to the electrode assembly provided by the embodiment of the invention, the problem of short circuit of the adjacent pole pieces caused by turnover of the diaphragm can be solved.

Description

Technical Field

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

[0002] Energy conservation and emission reduction are the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their advantages in energy conservation and environmental protection. For electric vehicles, battery technology is an important factor in their development.

[0003] In the structure of the battery, the electrode assembly is an important component, and the winding process of the electrode assembly is a crucial link. During the winding process of the electrode assembly, the diaphragm is prone to folding, which in turn causes the adjacent pole pieces to short-circuit, causing the electrode assembly to malfunction and affecting the battery yield. Summary of the invention

[0004] In view of this, the present application provides an electrode assembly, a battery cell, a battery and an electrical device, which can solve the problem of short circuit between adjacent electrodes caused by folding of the diaphragm.

[0005] An embodiment of the first aspect of the present application provides an electrode assembly, comprising:

[0006] First pole piece;

[0007] A diaphragm, the diaphragm comprising two folded diaphragm layers, the two diaphragm layers respectively covering opposite ends of the first pole piece along the thickness direction thereof;

[0008] The diaphragm layer has a first edge portion extending beyond the end of the first pole piece along the width direction of the first pole piece, the first edge portion is opposite to the folded end of the diaphragm, and the first edge portions of the two diaphragm layers are connected to each other to form a first joint portion.

[0009] The electrode assembly provided in the embodiment of the present application includes a first pole piece and a diaphragm, the diaphragm includes two diaphragm layers formed by folding, the two diaphragm layers respectively cover the two ends of the first pole piece along its thickness direction, and the two diaphragm layers are connected to each other beyond the first pole piece, so that the diaphragm can completely cover the first pole piece, the relative position of the first pole piece and the diaphragm is fixed, and the problem of diaphragm folding is not easy to occur. Even if the diaphragm is folded, the problem of contact between the positive and negative pole pieces will not occur, thereby reducing the situation where the pole piece is exposed outside the diaphragm and causes contact with the adjacent pole piece and short circuit, thereby improving the yield of the battery. At the same time, the first edge portions of the two diaphragm layers are connected to each other through the first joint portion, so that the position of the diaphragm and the first pole piece can be relatively fixed, and the diaphragm and the first pole piece do not need to be compounded. The portion of the diaphragm covering the first pole piece will not be subjected to rolling pressure, so that the particles on the surface of the diaphragm will not be reduced in height due to rolling pressure, and the diaphragm can effectively maintain the gap between the pole pieces, which is conducive to maintaining the dynamic performance of the battery cell in the later stage, and the portion of the diaphragm covering the first pole piece will not deteriorate in air permeability due to rolling pressure.

[0010] In some embodiments, the first pole piece includes a pole piece body and a pole ear extending outward from an edge of the pole piece body, the pole ear and the first edge portion are arranged on the same side of the pole piece body, and the first edge portion covers a portion of the pole ear along the width direction of the first pole piece.

[0011] By adopting the above technical solution, the diaphragm can completely wrap the pole piece body, and the part of the diaphragm covering the pole piece body is not easy to fold. Even if the end of the diaphragm is folded, the pole piece body will not be exposed to cause a short circuit; the first edge portion covers part of the pole ear so that the exposed part of the pole ear can be connected to the electrode terminal.

[0012] In some embodiments, the length of the pole lug is less than or equal to the length of the pole piece body.

[0013] By adopting the above technical solution, the diaphragm can wrap the first pole piece of the die-cut pole ear structure or the first pole piece of the full pole ear structure. In such an electrode assembly, the relative position of the diaphragm and the first pole piece can be fixed, reducing the probability of the diaphragm folding. Even if the diaphragm is folded, it is not easy to cause contact and short circuit between adjacent pole pieces.

[0014] In some embodiments, the first combining portion and the pole tab are partially overlapped, and the pole tab is compositely bonded to the first edge portion; or, the first combining portion and the pole tab are staggered.

[0015] By adopting the above technical solution, the pole ear can be compositely bonded to the diaphragm layer, and the pole ear can also be staggered with the first bonding portion, which can be flexibly selected according to the parameters of the electrode assembly and the process conditions.

[0016] In some embodiments, the diaphragm layer further has a covering portion covering the pole piece body; wherein the covering portion is in contact with the pole piece body, or there is a gap between the covering portion and the pole piece body.

[0017] By adopting the above technical solution, the diaphragm is folded to wrap around the first pole piece and the first edge portion on the pole ear side is compositely connected, so that the diaphragm can be stably fixed on the first pole piece through the joint, and the diaphragm is not easily separated from the first pole piece and the first pole piece is not easily exposed to the outside world. The diaphragm does not need to be connected to the first pole piece through rolling or other processes, so that the covering portion has better air permeability.

[0018] In some embodiments, the air permeability of the cover portion ranges from 100 to 300 s / cc.

[0019] By adopting the above technical solution, the electrode assembly does not need to roll-compound the diaphragm and the first electrode plate, so that the air permeability range of the covering part can be set within the range of 100s / cc to 300s / cc, thereby achieving a higher ion transmission efficiency and improving the performance of the battery.

[0020] In some embodiments, the diaphragm layer further has a second edge portion located at the folded end, and the second edge portion extends beyond an end portion of the first pole piece along a width direction of the first pole piece.

[0021] By adopting the above technical solution, the second edge portion exceeds the end of the first pole piece, which facilitates the two second edge portions to wrap the end of the first pole piece together.

[0022] In some embodiments, ends of two second edge portions are integrally connected, and a width of the second edge portion is 1 to 5 mm.

[0023] By adopting the above technical solution, it is convenient for the diaphragm to wrap the first pole piece, and it is not easy to cause the first pole piece to move between the two diaphragm layers.

[0024] In some embodiments, two of the second edge portions are connected to each other to form a second joint portion.

[0025] By adopting the above technical solution, the diaphragm layer also achieves composite bonding at the folded end of the diaphragm, that is, the diaphragm forms a bonding portion on both opposite sides of the first pole piece. In this way, the first pole piece is not easy to move between the two diaphragm layers, which is beneficial to the stacking and alignment of the first pole piece and the second pole piece, and further beneficial to ensuring the electrical performance of the electrode assembly.

[0026] In some embodiments, along the width direction of the first pole piece, the width of the second edge portion is 1 to 20 mm.

[0027] By meeting the above range, the two opposite second edge portions can be conveniently composite-bonded, and the second edge portions do not need to be set too wide to reduce the probability of folding of the second edge portions.

[0028] In some embodiments, the second combining portion is symmetrically arranged with the first combining portion.

[0029] In some embodiments, along the width direction of the first pole piece, the width of the pole ear beyond the first edge portion is 1 to 40 mm.

[0030] By satisfying the above conditions, the width range of the electrode tab beyond the separator layer is set, and the portion of the electrode tab exposed outside the separator layer can be stably connected to the electrode terminal.

[0031] In some embodiments, along the width direction of the first pole piece, the width of the portion of the pole tab covered by the diaphragm layer accounts for 1 / 3 to 2 / 3 of the width of the pole tab.

[0032] By satisfying the above conditions, the width range of the electrode tab beyond the separator layer is set, and the portion of the electrode tab exposed outside the separator layer can be stably connected to the electrode terminal.

[0033] In some embodiments, along the width direction of the first pole piece, the width of the first edge portion is 1 to 20 mm.

[0034] By satisfying the above conditions, the two relative first edge portions both extend beyond the pole piece body and can be compositely bonded on the outside of the pole piece body, so that the relative position of the diaphragm and the first pole piece is fixed, the diaphragm is not easy to fold and the pole ear body is not easy to expose; and the diaphragm and the pole piece body do not need to be rolled and composited, so as to avoid the deterioration of the air permeability of the diaphragm above the pole piece body and the inability to effectively maintain the gap between the pole pieces.

[0035] In some embodiments, along the width direction of the first pole piece, the width of the first combining portion is 2 to 20 mm.

[0036] By satisfying the above conditions, the width of the first joint portion is less than or equal to the width of the first edge portion, and the diaphragm and the pole piece body do not need to be rolled and laminated.

[0037] In some embodiments, along the width direction of the first pole piece, the offset length of the two first edge portions is 2 mm to 5 mm.

[0038] By controlling the offset length range of the first edge portion, the first connecting portion can have a sufficient size to stably and fixedly connect the two diaphragm layers.

[0039] In some embodiments, the first combining portions are continuously distributed along the length direction of the diaphragm, or a plurality of the first combining portions are spaced apart and distributed along the length direction of the diaphragm.

[0040] In the electrode assembly provided in the embodiment of the present application, the two first edge portions can be interconnected to form a continuous first connecting portion or a plurality of first connecting portions arranged at intervals, both of which can stably connect the two diaphragm layers, and the manufacturing method is flexible and convenient.

[0041] In some embodiments, a plurality of the first combining portions are arranged at equal intervals, a length of the first combining portion is greater than 2 mm, and a distance between two adjacent first combining portions is 2 to 100 mm.

[0042] By adopting the above technical solution, the two diaphragm layers are interconnected through multiple first joints. The length of the first joints meets the above conditions, which can make the two diaphragm layers stably and reliably connected and not easily separated to expose the electrode body; the spacing between the first joints has a large selection range and can be flexibly set according to the parameters of the electrode assembly and the process conditions.

[0043] In some embodiments, a connection pattern is formed on the first combining portion, and the two diaphragm layers are connected at the connection pattern.

[0044] By adopting the above technical solution, the two diaphragm layers are connected at the connection pattern to achieve a composite connection; the connection pattern can enhance the bonding strength of the two diaphragm layers and further reduce the probability of separation of the two diaphragm layers.

[0045] In some embodiments, the connection pattern includes at least one of a dot pattern, a stripe pattern, a polygonal pattern, a circular pattern, and an elliptical pattern.

[0046] By adopting the above technical solution, the two diaphragm layers are not easily separated along the connection pattern, which further reduces the probability of the two diaphragm layers being separated and the probability of the diaphragm being folded.

[0047] In some embodiments, the electrode assembly further includes a second pole piece, and the first pole piece, the diaphragm and the second pole piece are wound together; one of the first pole piece and the second pole piece is a cathode piece, and the other is an anode piece.

[0048] By adopting the above technical solution, the electrode assembly adopts a winding structure, and the first electrode sheet wrapped by the diaphragm can be a cathode sheet or an anode sheet. The electrode assembly after winding is not prone to the situation where the diaphragm is folded and causes a short circuit between the cathode and anode sheets.

[0049] An embodiment of the second aspect of the present application provides a battery cell, comprising the electrode assembly as described in the first aspect.

[0050] An embodiment of the third aspect of the present application provides a battery, comprising the battery cell as described in the second aspect.

[0051] An embodiment of the fourth aspect of the present application provides an electrical device, comprising the battery as described in the third aspect.

[0052] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or conventional technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0054] Figure 1 A schematic diagram of the structure of an electric device provided in some embodiments of the present application;

[0055] Figure 2 A schematic diagram of the exploded structure of a battery provided in some embodiments of the present application;

[0056] Figure 3 A schematic diagram of the exploded structure of a battery cell provided in some embodiments of the present application;

[0057] Figure 4 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0058] Figure 5 for Figure 4 A cross-sectional view of the electrode assembly shown along line II-II;

[0059] Figure 6 for Figure 5 A partial schematic diagram of the diaphragm and the first electrode piece in the electrode assembly shown;

[0060] Figure 7 to Figure 9 Schematic diagrams of structures of different first combining parts in electrode assemblies provided in some embodiments of the present application;

[0061] Fig.10 A schematic diagram of the structure of an electrode assembly provided in some other embodiments of the present application;

[0062] Fig.11 for Fig.10 A partial schematic diagram of the electrode assembly shown;

[0063] Fig.12 for Fig.11 A cross-sectional view of the electrode assembly shown along line III-III;

[0064] Fig.13 for Fig.12 A partial schematic diagram of the diaphragm and the first electrode piece in the electrode assembly shown;

[0065] Figure 14 to Figure 16 Schematic diagrams of structures of different second combining parts in electrode assemblies provided in other embodiments of the present application;

[0066] Fig.17 In some embodiments Figure 3 A cross-sectional view of the battery cell along line II is shown;

[0067] Fig.18 In some other embodiments Figure 3 A cross-sectional view of the battery cell along line II is shown;

[0068] Fig.19 A schematic diagram of the structure of a battery cell provided in some other embodiments;

[0069] Fig. 20 A schematic structural diagram of a battery cell provided in some further embodiments.

[0070] The meanings of the marks in the figure are:

[0071] 100. Electrode assembly;

[0072] 10. first pole piece; 11. pole piece body; 12. pole ear;

[0073] 20, diaphragm; 21, diaphragm layer; 211, first edge portion; 212, covering portion; 213, second edge portion; 22, first joint portion; 221, connection pattern; 23, second joint portion; 30, second pole piece;

[0074] 200, battery cell; 40, housing; 50, end cover; 51, electrode terminal;

[0075] 300, battery; 60, housing; 61, first part; 62, second part;

[0076] 1000. Electrical device; 400. Controller; 500. Motor. DETAILED DESCRIPTION

[0077] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0078] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0079] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0080] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0081] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0082] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0083] In the description of the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the embodiments of the present application.

[0084] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0085] At present, from the perspective of market development, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0086] In the structure of the battery, the electrode assembly is an important component, and the winding or lamination process of the electrode assembly is a crucial link. In the current electrode assembly, the area of ​​the diaphragm and the electrode sheet is mostly the same or roughly the same, and in the process of winding or laminating the electrode assembly, the diaphragm is prone to abnormal conditions such as folding; this makes it easy for the electrode sheet to be exposed when the diaphragm is folded. One of the functions of the diaphragm is to separate the adjacent cathode and anode sheets to reduce the occurrence of short circuits caused by contact between the cathode and anode sheets, thereby reducing electrode assembly failures and reducing the negative impact on the yield of the electrode assembly. Therefore, when the diaphragm is folded, it is easy to cause the cathode and anode sheets on both sides of the diaphragm to short-circuit, causing the electrode assembly to fail and affecting the yield of the battery.

[0087] In order to solve the problem that the folding of the diaphragm may cause a short circuit of the electrode, an embodiment of the present application provides an electrode assembly, wherein the diaphragm forms two diaphragm layers after being folded, and the two diaphragm layers are respectively arranged at opposite ends of the first electrode along its thickness direction, and the diaphragm layer has a first edge portion extending beyond the end of the first electrode along the width direction of the first electrode, and the first edge portion is arranged at the end of the diaphragm layer away from the folded end, and the first edge portions of the two diaphragm layers are connected to each other to form a first bonding portion.

[0088] In such an electrode assembly, the two diaphragm layers are integrally connected at one end of the folding end, and the parts of the two diaphragm layers that extend beyond the first pole piece are connected to each other. In this way, the diaphragm can cover the first pole piece, and the relative position of the first pole piece and the diaphragm is fixed, making it less likely for the diaphragm to fold. Even if the diaphragm is folded, there will be no contact between the positive and negative pole pieces. This reduces the risk of the pole piece being exposed outside the diaphragm, causing contact with the adjacent pole piece and causing a short circuit, thereby improving the yield of the battery.

[0089] The battery cell disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0090] For the convenience of description, the following embodiments are described by taking an electric device 1000 of an embodiment of the present application as a vehicle as an example.

[0091] refer to Figure 1 , Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application. The vehicle may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 300 is provided inside the vehicle, and the battery 300 may be provided at the bottom, head or tail of the vehicle. The battery 300 may be used to power the vehicle, for example, the battery 300 may be used as an operating power source for the vehicle. The vehicle may also include a controller 400 and a motor 500, and the controller 400 is used to control the battery 300 to power the motor 500, for example, for starting, navigating and driving the vehicle.

[0092] In some embodiments of the present application, the battery 300 can be used not only as an operating power source for the vehicle, but also as a driving power source for the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0093] refer to Figure 2 , Figure 2An exploded view of a battery 300 provided in some embodiments of the present application. The battery 300 includes a box 60 and a battery cell 200, and the battery cell 200 is accommodated in the box 60. Among them, the box 60 is used to provide a storage space for the battery cell 200, and the box 60 can adopt a variety of structures. In some embodiments, the box 60 may include a first part 61 and a second part 62, the first part 61 and the second part 62 cover each other, and the first part 61 and the second part 62 jointly define a storage space for accommodating the battery cell 200. The second part 62 may be a hollow structure with one end open, the first part 61 may be a plate-like structure, and the first part 61 covers the open side of the second part 62, so that the first part 61 and the second part 62 jointly define a storage space; the first part 61 and the second part 62 may also be hollow structures with one side open, and the open side of the first part 61 covers the open side of the second part 62. Of course, the box 60 formed by the first part 61 and the second part 62 may be in a variety of shapes, such as a cylinder, a cuboid, etc.

[0094] In the battery 300, there may be multiple battery cells 200, and the multiple battery cells 200 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 200 are both connected in series and in parallel. The multiple battery cells 200 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 200 is accommodated in the box 60; of course, the battery 300 may also be a battery 300 module formed by connecting multiple battery cells 200 in series, in parallel, or in a mixed connection, and then the multiple battery 300 modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 60. The battery 300 may also include other structures, for example, the battery 300 may also include a converging component for realizing electrical connection between the multiple battery cells 200.

[0095] Each battery cell 200 may be a secondary battery or a primary battery, or a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 200 may be cylindrical, flat, rectangular, or in other shapes.

[0096] refer to Figure 3 , Figure 3 The schematic diagram of the exploded structure of the battery cell 200 provided in some embodiments of the present application. The battery cell 200 refers to the smallest unit constituting the battery 300. As shown in the figure, the battery cell 200 includes a housing 40, an end cap 50, an electrode assembly 100 and other functional components.

[0097] The end cap 50 refers to a component that covers the opening of the shell 40 to isolate the internal environment of the battery cell 200 from the external environment. Without limitation, the shape of the end cap 50 can be adapted to the shape of the shell 40 to match the shell 40. Optionally, the end cap 50 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 50 is not easily deformed when squeezed and collided, so that the battery cell 200 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals 51 can be provided on the end cap 50. The electrode terminal 51 can be used to electrically connect to the electrode assembly 100 for outputting or inputting electrical energy of the battery cell 200. In some embodiments, the end cap 50 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 200 reaches a threshold. The material of the end cap 50 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this. In some embodiments, an insulating member may be provided inside the end cap 50, and the insulating member may be used to isolate the electrical connection components in the housing 40 from the end cap 50 to reduce the risk of short circuit. For example, the insulating member may be plastic, rubber, or the like.

[0098] The shell 40 is a component used to cooperate with the end cap 50 to form the internal environment of the battery cell 200, wherein the formed internal environment can be used to accommodate the electrode assembly 100, the electrolyte and other components. The shell 40 and the end cap 50 can be independent components, and an opening can be set on the shell 40, and the internal environment of the battery cell 200 is formed by covering the opening with the end cap 50 at the opening. Without limitation, the end cap 50 and the shell 40 can also be integrated. Specifically, the end cap 50 and the shell 40 can form a common connection surface before other components are put into the shell, and when the interior of the shell 40 needs to be encapsulated, the end cap 50 covers the shell 40. The shell 40 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 40 can be determined according to the specific shape and size of the electrode assembly 100. The material of the shell 40 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0099] The electrode assembly 100 is a component in the battery cell 200 where electrochemical reactions occur. One or more electrode assemblies 100 may be included in the housing 40. The electrode assembly 100 is mainly formed by winding or stacking cathode sheets and anode sheets, and a separator 20 is usually provided between the cathode sheets and the anode sheets. The portions of the cathode sheets and the anode sheets with active materials constitute the electrode body of the electrode assembly 100, and the portions of the cathode sheets and the anode sheets without active materials each constitute a tab. The cathode tab and the anode tab may be located together at one end of the electrode body or at both ends of the electrode body, respectively. During the charge and discharge process of the battery 300, the cathode active material and the anode active material react with the electrolyte, and the tabs are connected to the electrode terminals 51 to form a current loop.

[0100] The embodiment of the first aspect of the present application provides an electrode assembly 100, referring to Figures 4 to 7 , in the figure, the W direction is the width direction of the first pole piece 10, the L direction is the length direction of the first pole piece 10, and the T direction is the thickness direction of the first pole piece 10. The electrode assembly 100 includes a first pole piece 10 and a diaphragm 20. The diaphragm 20 includes two diaphragm layers 21 formed by folding, and the two diaphragm layers 21 respectively cover the opposite ends of the first pole piece 10 along the thickness direction thereof; the diaphragm layer 21 has a first edge portion 211 extending beyond the end of the first pole piece 10 along the width direction of the first pole piece 10, and the first edge portion 211 is opposite to the folded end of the diaphragm 20, and the first edge portions 211 of the two diaphragm layers 21 are connected to each other to form a first joint portion 22.

[0101] Please refer to Figure 4 , Fig.18 The first pole piece 10 is covered by the diaphragm 20 , d1 indicates the width of the pole piece body in the first pole piece 10 , d2 indicates the width of the diaphragm layer 21 , and d1 is smaller than d2 .

[0102] The first pole piece 10 and the diaphragm 20 are respectively continuous integral structures. In other embodiments, the first pole piece 10 may also be a plurality of pole pieces with separate structures, and a continuous diaphragm 20 is provided on both sides of the plurality of pole pieces along the thickness direction of the pole pieces.

[0103] The first electrode sheet 10 and the diaphragm 20 are in a state of multiple reciprocating folding, so that the first electrode sheet 10 and the diaphragm 20 are roughly bent back and forth in a Z shape. The second electrode sheet 30 is arranged between two adjacent layers of the first electrode sheet 10 of the bending structure. The first electrode sheet 10 and the second electrode sheet 30 are separated by the diaphragm 20 to form a stacked structure electrode assembly 100. The polarities of the first electrode sheet 10 and the second electrode sheet 30 are opposite. When one of them is a cathode sheet, the other is an anode sheet. The diaphragm 20 is a microporous membrane used to separate the first electrode sheet 10 and the second electrode sheet 30. It is a polymer functional material with nano-scale micropores, which is used to prevent the two electrode sheets from contacting and short-circuiting, while allowing electrolyte ions to pass through.

[0104] The diaphragm 20 is used to wrap the first pole piece 10. The diaphragm 20 includes two diaphragm layers 21 formed by folding, that is, the diaphragm 20 is folded along its width direction to form two stacked diaphragm layers 21, and the two diaphragm layers 21 are integrally connected at the folded end of the diaphragm 20. The diaphragm 20 can be folded in half from its center to form two diaphragm layers 21 of equal size, or the diaphragm 20 can be folded from a position close to its center to form two diaphragm layers 21 of unequal size. The two diaphragm layers 21 respectively cover the opposite ends of the first pole piece 10 along its thickness direction, so that the diaphragm 20 can completely wrap the pole piece body of the first pole piece 10 to prevent the first pole piece 10 from directly contacting the second pole piece 30 and causing a short circuit.

[0105] Each diaphragm layer 21 has a first edge portion 211 that exceeds the end of the first pole piece 10. The first edge portion 211 is located at the end of the diaphragm layer 21 away from the folded end of the diaphragm 20. It can be seen that the width of the diaphragm 20 is greater than twice the width of the first pole piece 10. In this way, the diaphragm 20 can wrap the first pole piece 10. The two diaphragm layers 21 are integrally connected at the folded end of the diaphragm 20, that is, the two diaphragm layers 21 can wrap the first pole piece 10 together at the folded end; the two diaphragm layers 21 are connected to each other at the open end of the diaphragm 20 and form a first joint portion 22, so that the two diaphragm layers 21 can wrap the first pole piece 10 at both opposite ends of the first pole piece 10 along its width direction, so that the first pole piece 10 is accommodated in the accommodation space formed by the diaphragm 20.

[0106] The first edge portions 211 of the two diaphragm layers 21 can be fixedly connected in a variety of ways. For example, the connection method of the two first edge portions 211 includes at least one of rolling, melting, ultrasonic welding, and colloid bonding. "First joint" refers to the part where the two first edge portions 211 are fixedly connected to each other, and the two diaphragm layers 21 are compositely bonded through the first joint 22. The "composite bonding" referred to in the embodiments of the present application refers to composite connection and mutual bonding. The composite bonding can be implemented by at least one of rolling equipment rolling, heat sealing and melting sealing, ultrasonic roller welding, colloid bonding, etc.

[0107] The first combining portion 22 may completely overlap with the first edge portion 211 , or the first combining portion 22 may be smaller than the length of the first edge portion 211 ; the number of the first combining portions 22 may be one or more, and when there are multiple first combining portions 22 , the multiple first combining portions 22 are spaced apart along the extension direction of the first edge portion 211 .

[0108] Optionally, the composite connection of the two diaphragm layers 21 is located in the first edge portion 211 , and the pole piece body 11 does not need to be rolled. It can be understood that the composite connection of the two diaphragm layers 21 can also extend from the first edge portion 211 to the pole piece body 11 .

[0109] The electrode assembly 100 provided in the embodiment of the present application includes a first electrode sheet 10 and a diaphragm 20, and the diaphragm 20 includes two diaphragm layers 21 formed by folding, and the two diaphragm layers 21 respectively cover the two ends of the first electrode sheet 10 along its thickness direction, and the two diaphragm layers 21 are connected to each other at parts exceeding the first electrode sheet 10. In this way, the diaphragm 20 can completely cover the first electrode sheet 10, and the relative positions of the first electrode sheet 10 and the diaphragm 20 are fixed, and the problem of folding of the diaphragm 20 is not easy to occur. Even if the diaphragm 20 is folded, the problem of contact between the positive and negative electrode sheets will not occur, thereby reducing the situation where the electrode sheet is exposed outside the diaphragm 20, causing contact with the adjacent electrode sheet and short circuit, thereby improving the yield of the battery. At the same time, the first edge portions 211 of the two diaphragm layers 21 are connected to each other through the joint, so that the positions of the diaphragm 20 and the first pole piece 10 can be relatively fixed, and the diaphragm 20 and the first pole piece 10 do not need to be compounded. The portion of the diaphragm 20 covering the first pole piece 10 will not be rolled, so that the particles on the surface of the diaphragm 20 will not be reduced in height due to rolling. The diaphragm 20 can effectively maintain the gap between the pole pieces, which is beneficial to maintaining the dynamic performance of the battery cell in the later stage. In addition, the portion of the diaphragm 20 covering the first pole piece 10 will not have its air permeability deteriorated due to rolling.

[0110] In some embodiments, the first pole piece 10 includes a pole piece body 11 and a pole ear 12 extending outward from the edge of the pole piece body 11 , the pole ear 12 and the first edge portion 211 are arranged on the same side of the pole piece body 11 , and the first edge portion 211 covers a portion of the pole ear 12 along the width direction of the first pole piece 10 .

[0111] Specifically, the first pole piece 10 includes a current collector and an active material layer, the pole piece body 11 is the portion of the current collector coated with the active material layer, and the pole ear 12 protrudes from one side of the pole piece body 11 and is not coated with the active material layer.

[0112] The pole tab 12 can be manufactured by die-cutting, or the pole tab 12 is directly formed by the portion of the current collector that is not coated with the active material layer, that is, the first pole piece 10 is a full-pole tab structure.

[0113] When the first pole piece 10 is a continuously wound structure, the number of pole ears 12 can be multiple, and multiple pole ears 12 are stacked to improve the current capacity. The second pole piece 30 also includes pole ears 12, and the pole ears 12 on the first pole piece 10 and the pole ears 12 on the second pole piece 30 are respectively cathode and anode ears 12 and are staggered.

[0114] The first edge portion 211 of the diaphragm layer 21 is located on the side of the first pole piece 10 where the pole ear 12 is provided, and the first edge portion 211 covers part of the pole ear 12 along the width direction of the first pole piece 10 so that the diaphragm 20 wraps the pole piece body 11 and exposes part of the pole ear 12, and the exposed part of the pole ear 12 is used to connect to the electrode terminal 51.

[0115] By adopting the above technical solution, the diaphragm 20 can completely wrap the pole piece body 11, and the part of the diaphragm 20 covering the pole piece body 11 is not easy to fold. Even if the end of the diaphragm 20 is folded, the pole piece body 11 will not be exposed to cause a short circuit; the first edge portion covers part of the pole ear 12, so that the exposed part of the pole ear 12 can be connected to the electrode terminal 51.

[0116] Please refer to Figures 3 to 6 In some embodiments, the first combining portion 22 and the pole tab 12 are partially overlapped, and the pole tab 12 is compositely bonded to the first edge portion 211 ; or, the first combining portion 22 and the pole tab 12 are staggered.

[0117] Since the first edge portion 211 covers the portion 212 of the pole lug 12, the first combining portion 22 of the two layers of the first edge portions 211 can overlap or staggered with the pole lug 12. For example, the first combining portion 22 extends along the first edge portion 211 and the length of the first combining portion 22 is equal to the length of the first edge portion 211. Then, when the two layers of the first edge portions 211 are compounded, the pole lug 12 can be compounded and bonded with the two layers of the first edge portions 211; when the length of the first combining portion 22 is less than the length of the first edge portion 211, the first combining portion 22 can be staggered with the pole lug 12.

[0118] By adopting the above technical solution, the pole tab 12 can be compositely bonded with the diaphragm layer 21 , and the pole tab 12 can also be staggered with the first connecting portion 22 , which can be flexibly selected according to the parameters of the electrode assembly 100 and the process conditions.

[0119] Please refer to Figure 6 The diaphragm layer 21 also has a covering portion 212 covering the pole piece body 11 , wherein the covering portion 212 is in contact with the pole piece body 11 , or there is a gap between the covering portion 212 and the pole piece body 11 .

[0120] The covering portion 212 covers the electrode body 11, that is, the covering portion 212 covers the portion of the first electrode 10 coated with the active material layer. The covering portion 212 may be in contact with the electrode body 11, or there may be a gap between the covering portion 212 and the electrode body 11.

[0121] In order to reduce the probability of the diaphragm 20 being separated from the electrode and causing the electrode to be exposed, the diaphragm 20 is currently mostly composited on the electrode; and the composite of the diaphragm 20 and the electrode mostly includes a rolling process. The rolling of the diaphragm 20 and the electrode is likely to have a negative impact on the air permeability of the diaphragm 20, and may even cause the closure of the pores of the diaphragm 20, thereby having a negative impact on the transmission efficiency of lithium ions and other plasmas; the rolling of the diaphragm 20 and the electrode will also cause the height of the particles of the part of the diaphragm 20 covering the active material layer to be reduced, which is not conducive to the diaphragm 20 maintaining the gap between the electrode plates.

[0122] In this embodiment, the diaphragm 20 is folded and wrapped around the first pole piece 10, and the first edge portion 211 on the side of the pole ear 12 is compositely connected, so that the diaphragm 20 can be fixed on the first pole piece 10 more stably through the first joint portion 22, and the diaphragm 20 is not easily separated from the first pole piece 10, and the first pole piece 10 is not easily exposed to the outside world. Therefore, at this time, the diaphragm 20 does not need to be connected to the first pole piece 10 by rolling or other processes, that is, the covering portion 212 can be in contact with the first pole piece 10, or there is a gap between the covering portion 212 and the first pole piece 10, so that the covering portion 212 has good air permeability. In the electrode assembly 100 provided in this embodiment, since the covering portion 212 of the diaphragm 20 is not rolled, the gap between the pole pieces can be maintained at 20 to 100um.

[0123] By adopting the above technical solution, the diaphragm layer 21 is in contact with the first pole piece 10 or there is a gap between the diaphragm layer 21 and the first pole piece 10, and the diaphragm 20 does not need to be compositely connected with the pole piece body 11, thereby alleviating the situation in which the air permeability of the diaphragm 20 deteriorates due to composite and the diaphragm 20 cannot maintain the pole piece gap.

[0124] In some embodiments, the air permeability of the cover portion 212 ranges from 100 to 300 seconds per cubic centimeter (s / cc). For example, the air permeability of the cover portion 212 can be 100 s / cc, 150 s / cc, 200 s / cc, 250 s / cc, 300 s / cc, etc.

[0125] Air permeability refers to the permeability of air through fabrics (including traditional textiles and products, non-woven fabrics, blankets, high-permeability paper, filter materials, leather, polyethylene films, polytetrafluoroethylene films, polyurethane soft foams, various felts, etc.), and is expressed as the rate at which air flows vertically through a sample under specified sample area, pressure drop, and time conditions. Therefore, air permeability represents the amount of air that passes through a material per second. The unit of air permeability in this embodiment is s / cc, where s is a time unit, which refers to seconds, and cc is a volume unit, which refers to cubic centimeter (cm3). The conversion relationship is 1 cubic meter = 1000 cubic decimeters = 1,000,000 cubic centimeters.

[0126] If the permeability of the diaphragm 20 is too high, the pores of the diaphragm 20 are equivalent to closed pores, and the ions of the electrolyte cannot pass through, and high ion conductivity cannot be achieved; while if the permeability is too low, it is equivalent to the pores of the diaphragm 20 being connected, the ion permeation resistance is low, and the energy density is high. The function of the covering part 212 is to allow the ions in the electrolyte to pass through and reduce the passage of other substances. Therefore, making the permeability of the covering part 212 within the range of 100s / cc to 300s / cc can not only reduce the resistance to the passage of ions, but also better block large particles of other substances. In addition, the permeability of the first bonding part 22 is greater than 300s / cc.

[0127] The electrode assembly 100 provided in the embodiment of the present application does not need to be roll-compounded to the diaphragm 20 and the first electrode plate 10, so that the air permeability range of the covering portion 212 can be set within the range of 100s / cc to 300s / cc, thereby enabling higher ion transmission efficiency and improving the performance of the battery 300.

[0128] like Figure 6 As shown, in some embodiments, the diaphragm layer 21 further includes a second edge portion 213 located at the folded end, and the second edge portion 213 exceeds the end of the first pole piece 10 along the width direction of the first pole piece 10 .

[0129] The second edge portion 213 is located at the folded end of the diaphragm 20 and the non-ear 12 side of the first pole piece 10 . The second edge portion 213 extends beyond the end of the first pole piece 10 , so that the two second edge portions 213 can wrap the end of the first pole piece 10 together.

[0130] like Figures 4 to 6 In some embodiments, the ends of the two second edge portions 213 are integrally connected, and the width of the second edge portion 213 is 1 to 5 mm.

[0131] The ends of the two second edge portions 213 are connected as one body, that is, the two second edge portions 213 are connected as one body by folding. The width of the second edge portion 213 is, for example, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, etc. If the width of the second edge portion 213 is too small, it is easy to cause the two second edge portions 213 to be inconvenient to wrap the first electrode sheet 10; if the width of the second edge portion 213 is too large, it is easy to cause the first electrode sheet 10 to move between the two diaphragm layers 21, so that the stacking alignment accuracy of the first electrode sheet 10 and the second electrode sheet 30 is affected, thereby affecting the performance of the electrode assembly 100.

[0132] By adopting the above technical solution, the second edge portions 213 of the two diaphragm layers 21 are connected as one body, and the second edge portions 213 do not need to be compositely connected by rolling or the like, so that the two diaphragm layers 21 can wrap the end of the first pole piece 10, thereby improving the process efficiency; and, the width range of the second edge portion 213 is set, which makes it convenient for the diaphragm 20 to wrap the first pole piece 10 and is not likely to cause the first pole piece 10 to move between the two diaphragm layers 21.

[0133] Please refer to Figures 4 to 6 , the width of the first edge portion 211 is 1 to 20 mm.

[0134] The above width range is the width range along the width direction of the first pole piece 10. The first edge portion 211 is the area of ​​the first pole piece 10 that exceeds the pole piece portion. Along the width direction of the first pole piece 10, the width of the first edge portion 211 is 1 to 20 mm, so that two opposite first edge portions 211 can be compositely bonded; further, the width of the first edge portion 211 can be 2 to 20 mm; further, the width of the first edge portion 211 can be 5 to 20 mm, which is conducive to ensuring the composite connection area and connection strength.

[0135] The width of the first combining portion 22 is less than or equal to the width of the first edge portion 211 , and the width of the first combining portion 22 is 1 to 20 mm. Furthermore, in some embodiments, the width of the first combining portion 22 may be 2 to 20 mm.

[0136] By satisfying the above conditions, the two relative first edge portions 211 both extend beyond the pole piece body 11 and can be compositely bonded on the outer side of the pole piece body 11, so that the relative position of the diaphragm 20 and the first pole piece 10 is fixed, and the diaphragm 20 is not easy to fold and the pole ear 12 body is not easy to be exposed; and the diaphragm 20 and the pole piece body 11 do not need to be rolled and composited, so as to avoid the deterioration of the air permeability of the diaphragm 20 above the pole piece body 11 and the inability to effectively maintain the gap between the pole pieces.

[0137] In some embodiments, the two second edge portions 213 are compositely connected, the bonding force is greater than 2N, and the air permeability of the first bonding portion 22 is greater than 300s / cc; if the two second edge portions 213 are directly connected as one body and are not composited, the air permeability of the diaphragm 20 at the second edge portion 213 is in the range of 100 to 300s / cc.

[0138] Please refer to Figure 6 , the ends of the two first edge portions 211 are arranged flush. In some embodiments, the ends of the two first edge portions 211 may also be arranged offset, and the offset length of the two first edge portions 211 along the width direction of the first pole piece 10 is 2 mm to 5 mm. "Offset length" refers to the length of one first edge portion 211 exceeding the other first edge portion 211 along the width direction of the first pole piece 10.

[0139] When the ends of the two first edge portions 211 are arranged flush, the diaphragm 20 is folded in half from the center in the width direction to form two diaphragm layers 21 of equal width; when the ends of the two first edge portions 211 are arranged offset, the diaphragm 20 is not folded in half along the center, so that the widths of the two diaphragm layers 21 are unequal.

[0140] The offset length of the two first edge portions 211 is 2 mm to 5 mm, for example 2 mm, 3 mm, 4 mm, 5 mm, etc. By controlling the offset length range of the first edge portions 211, the first bonding portion 22 can have a sufficient size to stably and fixedly connect the two diaphragm layers 21.

[0141] The bonding force of the region where the diaphragm 20 and the first electrode sheet 10 are combined is greater than 1N, the bonding force of the diaphragm 20 in the region without the electrode tab 12 is greater than 2N, and the air permeability of the first joint portion 22 is greater than 300s / cc.

[0142] Please refer to Figures 10 to 13 , Fig.18 Other embodiments of the present application provide an electrode assembly 100, the electrode assembly 100 includes a first electrode sheet 10 and a diaphragm 20, the diaphragm 20 includes two diaphragm layers 21 formed by folding, the diaphragm layer 21 has a first edge portion 211 extending beyond the end of the first electrode sheet 10 along the width direction of the first electrode sheet 10, the first edge portion 211 is arranged at an end of the diaphragm layer 21 away from the folded end, the first edge portions 211 of the two diaphragm layers 21 are connected to each other and form a first bonding portion 22; the diaphragm layer 21 also has a second edge portion 213 located at the folded end, and the second edge portion 213 extends beyond the end of the first electrode sheet 10 along the width direction of the first electrode sheet 10.

[0143] In this embodiment, the two second edge portions 213 are connected to each other to form a second joint portion 23 , that is, the two second edge portions 213 can also be compositely bonded by at least one of rolling, melting, ultrasonic welding, and colloid bonding.

[0144] The second combining portion 23 formed by the two second edge portions 213 may have the same or different structure as the first combining portion 22 formed by the two first edge portions 211. Optionally, the first combining portion 22 and the second combining portion 23 are symmetrically arranged. It can be understood that the first combining portion 22 and the second combining portion 23 may also be asymmetrically arranged without affecting the connection effect of the diaphragm layer 21.

[0145] By adopting the above technical solution, the diaphragm layer 21 also achieves composite bonding at the folded end of the diaphragm 20, that is, the diaphragm 20 forms a bonding portion on both opposite sides of the first pole piece 10. In this way, the first pole piece 10 is not easy to move between the two layers of the diaphragm layer 21, which is beneficial to the stacking and alignment of the first pole piece 10 and the second pole piece 30, and further beneficial to ensuring the electrical performance of the electrode assembly 100.

[0146] like Fig.11 As shown, in some embodiments, the width K of the second edge portion 213 is 1-20 mm.

[0147] The width of the second edge portion 213 is 1 to 20 mm, for example, 1 mm, 2 mm, 5 mm, 10 mm, 20 mm, etc. By meeting the above range, the two opposite second edge portions 213 can be conveniently composite-bonded, and the second edge portion 213 does not need to be set too wide to reduce the probability of the second edge portion 213 being folded. In addition, the width of the second joint portion 23 is less than or equal to the width of the second edge portion 213, and the width of the second joint portion 23 can be 1 to 20 mm. Further, the range of the second joint portion 23 is 2 to 20 mm.

[0148] Fig.11 The width H of the first edge portion 211 is also illustrated. The width H of the first edge portion 211 may also be 1-20 mm, wherein the widths of the first edge portion 211 and the second edge portion 213 may be equal or different.

[0149] In some embodiments, the second combining portion 23 is symmetrically arranged with the first combining portion 22, that is, the second combining portion 23 is symmetrically arranged with the first combining portion 22 relative to the center line of the diaphragm 20, and the first combining portion 22 and the second combining portion 23 have the same size and pattern. In this way, when manufacturing the electrode assembly, the first combining portion 22 and the second combining portion 23 can be formed simultaneously through a composite process, thereby improving the manufacturing efficiency.

[0150] Please refer to Figures 3 to 18 In some embodiments, along the width direction of the pole piece, the width of the pole ear 12 beyond the first edge portion 211 is 1 to 40 mm.

[0151] Specifically, the width of the tab 12 beyond the first edge portion 211 may be 1 mm, 5 mm, 10 mm, 20 mm, 40 mm, etc. Since the tab 12 needs to be electrically connected to the electrode terminal 51, the tab 12 needs to partially exceed the first edge portion 211. It can be understood that the maximum width of the tab 12 beyond the first edge portion 211 is related to the extension size of the tab 12 itself.

[0152] By satisfying the above conditions, the width range of the electrode tab 12 beyond the separator 20 is set, and the portion of the electrode tab 12 exposed outside the separator layer 21 can be stably connected to the electrode terminal 51 .

[0153] In some embodiments, along the width direction (W direction) of the first pole piece 10 , the width of the portion 212 of the pole tab 12 covered by the diaphragm layer 21 accounts for 1 / 3 to 2 / 3 of the width of the pole tab 12 .

[0154] The tab 12 may be covered by the first edge portion 211, or may be covered by the first edge portion 211 and the area of ​​the diaphragm layer 21 adjacent to the first edge portion 211. Specifically, the width of the portion 212 of the tab 12 covered by the diaphragm layer 21 may account for 1 / 3, 1 / 2, 2 / 3, etc. of the width of the tab 12.

[0155] If the width of the portion of the electrode tab 12 covered by the diaphragm layer 21 is too small, that is, the width of the first edge portion 211 is too small, there may be a problem of insufficient size of the joint portion, causing the two diaphragm layers 21 to separate; if the width of the portion of the electrode tab 12 covered by the diaphragm layer 21 is too large, it will be inconvenient to connect the electrode tab 12 to the electrode terminal 51.

[0156] The above conditions set the ratio range of the width of the tab 12 covered by the diaphragm layer 21 to the width of the tab 12. By adopting the above technical solution, the joint has high stability and is not easy to collapse. At the same time, the tab 12 can be more stably connected to the electrode terminal 51.

[0157] Please refer to Figure 4 , Figure 8 , Fig.10 , Fig.16 In some embodiments, the first combining portion 22 is continuously distributed along the length direction of the diaphragm 20 , that is, the first combining portion 22 is in a long strip shape and extends along the length direction of the diaphragm 20 .

[0158] During manufacturing, the folded diaphragm 20 is wrapped on the first pole piece 10, the first edge portion 211 of the diaphragm layer 21 exceeds the pole piece body 11, and the two first edge portions 211 are compositely connected by continuous composite method to form a continuous first joint portion 22. For the continuous first joint portion 22, the bonding force of the first joint portion 22 is greater than 2N.

[0159] Taking the rolling compounding method as an example, the two first edge portions 211 can be rolled and compounded by a compounding roller to form a first joint portion 22 extending along the length direction of the diaphragm 20; taking the colloid bonding method as an example, the colloid can be applied on the first edge portion 211 by continuous coating. It can be understood that the first joint portion 22 can also be compounded by other continuous compounding methods.

[0160] Please refer to Figure 7 , Fig. 9 , Fig.14 and Fig.15 In other embodiments, a plurality of first coupling portions 22 are spaced apart and distributed along the length direction of the diaphragm 20 .

[0161] During the manufacturing process, the two first edge portions 211 are compounded by intermittent compounding to form a discontinuous first bonding portion 22. For the discontinuous first bonding portion 22, the bonding force of the first bonding portion 22 is greater than 1N.

[0162] Taking the roller-combination method as an example, a plurality of protrusions distributed at intervals are provided on the composite roller, and the two first edge portions 211 can be roll-combined by the plurality of protrusions to form a plurality of first joint portions 22 distributed at intervals along the length direction of the diaphragm 20; taking the colloid bonding method as an example, the colloid can be applied to the first edge portion 211 by intermittent coating. It is understood that the first joint portion 22 can also be composited by other intermittent bonding methods.

[0163] It can be understood that the first joint portion 22 on the first edge portion 211 and the second joint portion 23 on the second edge portion 213 can be realized by continuous compounding or intermittent compounding. Therefore, the second joint portion 23 can be continuously distributed along the length direction of the diaphragm 20 or a plurality of second joint portions 23 can be distributed at intervals along the length direction of the diaphragm 20.

[0164] In the electrode assembly 100 provided in the embodiment of the present application, the two first edge portions 211 can be interconnected to form a continuous first connecting portion 22 or a plurality of first connecting portions 22 arranged at intervals, both of which can stably connect the two diaphragm layers 21 and the manufacturing method is flexible and convenient.

[0165] Please refer to Figure 7 and Fig.14 In some embodiments, a plurality of first combining portions 22 are arranged at equal intervals, a length of a first combining portion 22 is greater than 2 mm, and a distance between two adjacent first combining portions 22 is 2 to 100 mm.

[0166] In this embodiment, the plurality of first bonding portions 22 are arranged at equal intervals, so that the bonding force between the two diaphragm layers 21 is relatively uniform; in other embodiments, the plurality of first bonding portions 22 may also be arranged at unequal intervals. When the diaphragm 20 further includes a plurality of second bonding portions 23, the plurality of second bonding portions 23 may also be arranged at equal intervals, the length of the second bonding portions 23 is greater than 2 mm, and the spacing between two adjacent second bonding portions 23 is 2 to 100 mm.

[0167] The length of the first combining portion 22 refers to the length of the first combining portion 22 along the length direction of the diaphragm 20 , that is, the length of the first combining portion 22 along the L direction. Figure 7 It is shown that a plurality of spaced first coupling portions 22 are arranged on the first edge portion 211. Fig.14 It is illustrated that a first combining portion 22 is provided on the first edge portion 211 and a second combining portion 23 is provided on the second edge portion 213, wherein the two first combining portions 22 on the first edge portion 211 have a width C and a width D, and the lengths of the width C and the width D are both greater than 2 mm to ensure the composite strength; wherein the width C and the width D may be equal or unequal.

[0168] The second connecting portion 23 on the second edge portion 213 has a width F and a width G. The lengths of the width F and the width G are both greater than 2 mm, and the width F and the width G may be equal or different.

[0169] Figure 7 The diagram shows the spacing B and spacing A between the first bonding portions 22 on the first edge portion 211. Fig.14 The diagram also illustrates the spacing F between the second connecting portions 23 on the second edge portion 213. In this embodiment, the spacing B is equal to the spacing A, and the lengths of the spacings A, B, and F are all in the range of 2 to 100 mm.

[0170] By adopting the above technical solution, the two diaphragm layers 21 are interconnected through multiple joints, and the length of the joints meets the above conditions, so that the two diaphragm layers 21 can be stably and reliably connected and are not easily separated to expose the electrode body 11; the spacing between the joints has a large selection range and can be flexibly set according to the parameters of the electrode assembly 100 and the process conditions.

[0171] Please refer to Figure 8 , Fig. 9 , Fig.15 , Fig.16 In some embodiments, a connection pattern 221 is formed on the first connecting portion 22 , and the two diaphragm layers 21 are connected at the connection pattern 221 .

[0172] The connection pattern 221 is a pattern formed by compounding, and the number of the connection pattern 221 can be one or more. When there are multiple connection patterns 221, the multiple connection patterns 221 are arranged at intervals. Similarly, the second connecting portion 23 can also be formed with a connection pattern.

[0173] Specifically, Fig. 9 As shown, the first connecting portion 22 may only include the connecting pattern 221, and the first connecting portion 22 is manufactured through a single composite process; Figure 8 , Fig.15 and Fig.16 As shown, the first bonding portion 22 includes a strip portion and a connecting pattern 221 arranged on the strip portion. The strip portion can extend along the length direction of the diaphragm 20, or a plurality of strip portions can be spaced apart along the length direction of the diaphragm 20. The strip portion and the connecting pattern 221 are manufactured through two composite processes, namely, the strip portion is manufactured through the first composite process (continuous composite or intermittent composite), and the connecting pattern 221 is manufactured through the second composite process (intermittent composite). The connecting pattern 221 can enhance the bonding strength of the two diaphragm layers 21.

[0174] By adopting the above technical solution, the two diaphragm layers 21 are connected at the connection pattern 221 to achieve a composite connection; the connection pattern 221 can enhance the bonding strength of the two diaphragm layers 21 and further reduce the probability of separation of the two diaphragm layers 21.

[0175] In some embodiments, the connection pattern 221 includes at least one of a dot pattern, a strip pattern, a polygonal pattern, a circular pattern, and an elliptical pattern, wherein the polygon includes a triangle, a square, a rhombus, a pentagon, a hexagon, etc., and the polygon may be a regular shape or an irregular shape.

[0176] Specifically, the connection pattern 221 can be produced by a printing roller having a printing pattern, or by ultrasonic welding. It can be understood that the connection pattern 221 can also be produced by other composite methods.

[0177] Since the connection pattern 221 has a preset shape, the two diaphragm layers 21 are not easily separated along the connection pattern 221 , which further reduces the probability of the two diaphragm layers 21 being separated and the probability of the diaphragm 20 being folded.

[0178] In the electrode assembly 100 provided in the above embodiment, the length of the electrode tab 12 may be less than or equal to the length of the electrode body 11 .

[0179] Please refer to Figures 4 to 16 , the length of the pole ear 12 is less than the length of the pole piece body 11. The pole ear 12 can be manufactured by die cutting, so that the pole ear 12 is in a sheet shape and protrudes from one side of the pole piece body 11. In the unfolded state, the plurality of pole ears 12 are spaced apart along the length direction of the first pole piece 10, and in the wound state, the plurality of pole ears 12 are stacked and fixedly connected.

[0180] Please refer to Fig.19 and Fig. 20 The length of the pole ear 12 is equal to the length of the pole piece body 11. The pole ear 12 is in a strip shape and extends along the pole piece body 11, that is, the first pole piece 10 is a full pole ear structure. When manufacturing the first pole piece 10, the pole ear 12 area is left blank in the coating process, and there is no need to coat the active material layer on the pole ear 12.

[0181] like Fig.19 and Fig. 20 As shown, d1 is the width of the electrode body 11, d2 is the width of the diaphragm 20 after folding, and the portion of the electrode ear 12 that exceeds the diaphragm 20 is used to connect the electrode terminal. Fig.19 In the illustrated embodiment, the diaphragm 20 is provided with a first joint portion 22 on one side of the tab 12. The first joint portion 22 is partially overlapped with the tab 12, and the tab 12 exceeds the first joint portion 22. Fig. 20In the embodiment shown, the diaphragm is provided with a first bonding portion 22 on one side of the tab 12 and a second bonding portion 23 on the non-tab side. In addition, the portion of the tab 12 covered by the diaphragm 20 (the root of the tab) can be compositely bonded, partially compositely bonded, or not compositely bonded to the diaphragm.

[0182] In the electrode assembly 100 provided in the embodiment of the present application, the diaphragm 20 can wrap the first pole piece 10 of the die-cut pole ear structure or the first pole piece 10 of the full pole ear structure. In such an electrode assembly 100, the relative position of the diaphragm 20 and the first pole piece 10 can be fixed, reducing the probability of the diaphragm 20 folding. Even if the diaphragm 20 is folded, it is not easy to cause a short circuit between adjacent pole pieces.

[0183] Please refer again Fig.18 , Fig.19 The electrode assembly 100 further includes a second electrode sheet 30. The first electrode sheet 10, the diaphragm 20 and the second electrode sheet 30 are wound together; one of the first electrode sheet 10 and the second electrode sheet 30 is a cathode sheet, and the other is an anode sheet.

[0184] The diaphragm 20 wraps the first pole piece 10 to separate the first pole piece 10 from the second pole piece 30 . The diaphragm 20 can also maintain a gap between the pole pieces in the electrode assembly 100 .

[0185] The electrode assembly 100 provided in the embodiment of the present application adopts a winding structure, and the first electrode sheet 10 wrapped by the diaphragm 20 can be a cathode sheet or an anode sheet. The electrode assembly 100 after winding is not prone to the situation where the diaphragm 20 is folded and causes a short circuit between the cathode and anode sheets.

[0186] Please refer to Figures 3 to 20 Some embodiments of the present application provide an electrode assembly 100, which can be used for square battery cells or cylindrical battery cells. The electrode assembly 100 includes a first pole piece 10 and a diaphragm 20. The first pole piece 10 includes a pole piece body 11 and a pole ear 12. The diaphragm 20 includes two stacked diaphragm layers 21. The two diaphragm layers 21 respectively cover the opposite ends of the first pole piece 10 along its thickness direction. The diaphragm 20 has a first edge portion 211 and a second edge portion 213 extending beyond the pole piece body 11 along the width direction of the first pole piece 10, and a covering portion 212 located between the first edge portion 211 and the second edge portion 213. The first edge portion 211 and the covering portion 212 separate the pole ear 12, and the second edge portion 213 is located at the folded end of the diaphragm 20. The two opposite first edge portions 211 are connected to each other and form a first joint portion 22, and the two opposite second edge portions 213 can be connected as a whole or form a second joint portion 23. Fig.17 and Fig.18 As shown, the electrode tab 12 is disposed on a side of the electrode assembly 100 facing the electrode terminal 51 , and a portion of the electrode tab 12 not covered by the diaphragm 20 is used to connect to the electrode terminal 51 .

[0187] In the above-mentioned electrode assembly 100, the diaphragm 20 can completely wrap the electrode body 11, and the diaphragm 20 is not easy to fold. Even if it is folded, the electrode body 11 will not be exposed to cause a short circuit between adjacent positive and negative electrodes, thereby improving the yield of battery cells and batteries.

[0188] The electrode assembly 100 further includes a second electrode sheet 30 , which is stacked and wound with the diaphragm 20 and the first electrode sheet 10 . It is understood that the second electrode sheet 30 may also be wrapped in the diaphragm 20 .

[0189] The embodiment of the second aspect of the present application provides a battery cell 200 , including the electrode assembly 100 provided in the first aspect.

[0190] refer to Figure 3 The battery cell 200 includes an end cap 50, a housing 40, an electrode assembly 100, and other functional components. The number of the electrode assembly 100 can be one or more.

[0191] refer to Figures 1 to 3 An embodiment of the third aspect of the present application provides a battery 300, including the battery cell 200 provided in the second aspect.

[0192] In the battery 300 , the battery cell 200 may be a square shell battery cell or a cylindrical battery cell; there may be multiple battery cells 200 , and the multiple battery cells 200 may be connected in series, in parallel, or in mixed connection.

[0193] The embodiment of the fourth aspect of the present application provides an electrical device 1000, comprising the battery 300 provided in the third aspect.

[0194] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An electrode assembly, characterized in that: include: First pole piece; A diaphragm, the diaphragm comprising two folded diaphragm layers, the two diaphragm layers respectively covering opposite ends of the first pole piece along the thickness direction thereof; The diaphragm layer has a first edge portion extending beyond the end of the first pole piece along the width direction of the first pole piece, the first edge portion is opposite to the folded end of the diaphragm, and the first edge portions of the two diaphragm layers are connected to each other to form a first joint portion.

2. The electrode assembly according to claim 1, characterized in that: The first pole piece includes a pole piece body and a pole ear extending outward from the edge of the pole piece body, the pole ear and the first edge portion are arranged on the same side of the pole piece body, and the first edge portion covers a portion of the pole ear along the width direction of the first pole piece.

3. The electrode assembly according to claim 2, characterized in that: The length of the pole ear is less than or equal to the length of the pole piece body.

4. The electrode assembly according to claim 3, characterized in that: The first joint portion is partially overlapped with the pole lug, and the pole lug is compositely bonded to the first edge portion; or, The first combining portion and the tab are staggered.

5. The electrode assembly according to claim 2, characterized in that: The diaphragm layer also has a covering portion covering the pole piece body; Wherein, the covering portion is in contact with the pole piece body, or there is a gap between the covering portion and the pole piece body.

6. The electrode assembly according to claim 5, characterized in that: The air permeability of the covering portion is in the range of 100 to 300 s / cc.

7. The electrode assembly according to any one of claims 2 to 6, characterized in that: The diaphragm layer further has a second edge portion located at the folded end, and the second edge portion exceeds an end portion of the first pole piece along a width direction of the first pole piece.

8. The electrode assembly according to claim 7, characterized in that: The ends of the two second edge portions are connected integrally, and the width of the second edge portion is 1 to 5 mm.

9. The electrode assembly according to claim 7, characterized in that: The two second edge portions are connected to each other to form a second connecting portion.

10. The electrode assembly according to claim 9, characterized in that: Along the width direction of the first pole piece, the width of the second edge portion is 1 to 20 mm.

11. The electrode assembly according to claim 9, characterized in that: The second combining portion is symmetrically arranged with the first combining portion.

12. The electrode assembly according to claim 2, characterized in that: Along the width direction of the first pole piece, the width of the pole ear beyond the first edge portion is 1 to 40 mm.

13. The electrode assembly according to claim 2, characterized in that: Along the width direction of the first pole piece, the width of the portion of the pole tab covered by the diaphragm layer accounts for 1 / 3 to 2 / 3 of the width of the pole tab.

14. The electrode assembly according to any one of claims 1 to 13, characterized in that: Along the width direction of the first pole piece, the width of the first edge portion is 1 to 20 mm.

15. The electrode assembly according to claim 14, characterized in that: Along the width direction of the first pole piece, the width of the first connecting portion is 2 to 20 mm.

16. The electrode assembly according to any one of claims 1 to 15, characterized in that: Along the width direction of the first pole piece, the offset length of the two first edge portions is 2 mm to 5 mm.

17. The electrode assembly according to any one of claims 1 to 16, characterized in that: The first joint portions are continuously distributed along the length direction of the diaphragm, or; The plurality of first combining portions are spaced apart and distributed along the length direction of the diaphragm.

18. The electrode assembly according to claim 17, characterized in that: A plurality of the first combining parts are arranged at equal intervals along the length direction of the diaphragm, the length of the first combining part is greater than 2 mm, and the interval between two adjacent first combining parts is 2 to 100 mm.

19. The electrode assembly according to claim 17, wherein: A connection pattern is formed on the first combining portion, and the two diaphragm layers are connected at the connection pattern.

20. The electrode assembly according to claim 19, characterized in that The connection pattern includes at least one of a dot pattern, a stripe pattern, a polygonal pattern, a circular pattern, and an elliptical pattern.

21. The electrode assembly according to any one of claims 1 to 20, characterized in that: The electrode assembly further includes a second pole piece, wherein the first pole piece, the diaphragm and the second pole piece are wound together; one of the first pole piece and the second pole piece is a cathode piece, and the other is an anode piece.

22. A battery cell, characterized in that: Comprising the electrode assembly as described in any one of claims 1-21.

23. A battery, characterized in that: Comprising the battery cell as claimed in claim 22.

24. An electrical device, characterized in that: Comprising a battery as claimed in claim 23.

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