Battery cell, battery device, and electric device

Abstract

The application provides a battery monomer, a battery device and an electric equipment. The battery monomer comprises a shell and one or more electrode assemblies. The electrode assemblies are accommodated in the shell. The electrode assemblies comprise pole pieces and separators arranged between the pole pieces. The separators comprise first separators and second separators. The electrode assemblies comprise first regions and second regions. The second regions are arranged close to the shell relative to the first regions. The first separators are located in the first regions. The second separators are located in the second regions. The adhesion of the first separators to the pole pieces is F1. The adhesion of the second separators to the pole pieces is F2. F1>F2, and F2 is less than or equal to 10 N / m. The second separators have lower adhesion. When the battery is subjected to external force impact, the second separators and the pole pieces can dissipate impact energy through sliding, thereby reducing the risk of pole piece cracking, piercing the separators and causing short circuit.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a battery cell, battery device, and electrical equipment. Background Technology

[0002] Batteries, as a new generation of energy storage and conversion devices, are widely used in portable electronic devices, electric vehicles, and other fields. When a battery cell is subjected to external impact, the electrode plate on the side closest to the impact area will crack brittlely, which will then puncture the separator, causing a short circuit inside the battery cell and potentially leading to safety issues such as fire and explosion. Utility Model Content

[0003] In view of this, the main technical problem to be solved by this application is how to reduce the risk of short circuit in a single battery cell when subjected to external impact.

[0004] To address the aforementioned technical problems, a first aspect of this application provides a battery cell, comprising a housing and one or more electrode assemblies, the electrode assemblies being housed within the housing, each electrode assembly including an electrode sheet and a separator disposed between the electrode sheets; the separator includes a first separator and a second separator, the electrode assembly including a first region and a second region, the second region being disposed close to the housing relative to the first region, the first separator being located in the first region, and the second separator being located in the second region; the adhesion force between the first separator and the electrode sheet is F1, the adhesion force between the second separator and the electrode sheet is F2, F1 > F2, and F2 ≤ 10 N / m.

[0005] In the technical solution of this application embodiment, by placing the second separator in the second region near the casing and adjusting its adhesion force to a specific range, when the battery cell is subjected to external impact, the low adhesion force between the second separator and the electrode allows for a certain degree of interface slippage under the impact force. This slippage process can dissipate some of the impact energy through interface friction loss, reducing the amount of impact energy directly transferred to the electrode, thereby reducing the risk of brittle cracking of the electrode due to stress concentration, and further reducing the probability of short circuit when the battery cell is subjected to external impact. In addition, by setting the first separator to have a higher adhesion force relative to the second separator, the structural stability of the electrode assembly can be effectively maintained, reducing the adverse effects on the battery cell performance caused by insufficient adhesion force of the separator.

[0006] In some embodiments, 5N / m≤F1-F2≤19N / m.

[0007] In the embodiments of this application, by limiting the difference between F1 and F2 to the above range, when the battery cell is subjected to an impact, it can effectively dissipate the impact energy through the slippage of the second separator and the electrode, and maintain the structural stability of the electrode assembly through the high adhesion of the first separator, thereby achieving a balance between safety and reliability of the battery cell.

[0008] In some embodiments, 15 N / m ≤ F1 ≤ 25 N / m; and / or, 6 N / m ≤ F2 ≤ 10 N / m.

[0009] In the embodiments of this application, by further limiting the values ​​of F1 and F2 to the above range, when the battery cell is subjected to an impact, it can effectively dissipate the impact energy through the slippage of the second separator, and maintain the structural stability of the electrode assembly through the high adhesion of the first separator, thereby achieving a balance between safety and reliability of the battery cell.

[0010] In some embodiments, the diaphragm includes a base membrane and an adhesive coating disposed on at least one side of the base membrane, the adhesive coating including one of polyvinylidene fluoride, polyacrylic acid, polymethyl methacrylate, polybutyl acrylate, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyurethane.

[0011] In the embodiments of this application, by defining the specific structure of the separator and the selection of the adhesive coating material, it is beneficial to further optimize the stability and electrochemical performance of the battery cells.

[0012] In some embodiments, the areal density of the adhesive coating on the first diaphragm is M1, and the areal density of the adhesive coating on the second diaphragm is M2, where 0.01 ≤ M2 / M1 ≤ 0.4.

[0013] In the embodiments of this application, by limiting the ratio of M2 to M1 within the above range, the adhesive coating of the second diaphragm can have a minimum necessary thickness, which maintains the basic adhesive force to reduce the possibility of delamination between the electrode and the second diaphragm, and achieves a lower adhesive force by having a significantly lower areal density than the first diaphragm, so as to meet the slippage requirements between the second diaphragm and the electrode in the event of an impact.

[0014] In some embodiments, 0.09 mg / cm 2 ≤M1≤0.13mg / cm 2 ; and / or, 0.02 mg / cm 2 ≤M2≤0.05mg / cm 2 .

[0015] In the embodiments of this application, by further limiting the values ​​of M2 and M1 to the aforementioned range, the adhesive coating of the second diaphragm can have a minimum necessary thickness. This maintains basic adhesive strength to reduce the possibility of delamination between the electrode and the second diaphragm, while achieving lower adhesive strength through a significantly lower areal density than the first diaphragm, thus meeting the slippage requirements between the second diaphragm and the electrode in the event of an impact. Furthermore, a value of M1 within the aforementioned range can provide stronger adhesive strength to the first diaphragm, which is beneficial for maintaining the structural stability of the electrode assembly.

[0016] In some embodiments, the areal density of the adhesive coating on the second diaphragm gradually increases along the direction from the second region toward the first region, and / or the areal density of the adhesive coating on the first diaphragm gradually increases.

[0017] In the embodiments of this application, by defining the direction from the second region toward the first region, the areal density of the adhesive coating of the second separator and / or the first separator gradually increases, so that the difference in adhesive force is achieved through a continuous transition rather than a step change. This design can reduce the risk of delamination or tearing caused by a sudden increase in stress at the interface between different regions. Furthermore, when a battery cell is impacted, the second region near the casing, with the lowest areal density of the adhesive coating, preferentially slips to dissipate energy, while the areal density gradually increases toward the first region, allowing the remaining impact energy to be gradually absorbed by regions with higher adhesive force. This gradient energy dissipation mechanism can both fully release impact energy and reduce the possibility of excessive displacement or misalignment between the electrode and the separator, thus helping to reduce the risk of short circuits in the battery cell.

[0018] In some embodiments, the thickness of the second region along the thickness direction of the electrode assembly accounts for 10% to 30% of the thickness of the electrode assembly.

[0019] In the embodiments of this application, by limiting the thickness of the second region to the above-mentioned range, on the one hand, the second region has sufficient thickness so that it can fully dissipate the impact energy through the sliding of the second diaphragm when subjected to external impact; on the other hand, by limiting the upper limit of the proportion of the second region, the risk of the electrode assembly becoming loose due to insufficient bonding strength can be reduced.

[0020] In some embodiments, the electrode assembly is a wound structure, which includes a flat region and a bent region; the flat region includes a first flat region and two second flat regions, and the bent region includes two first bent regions and two second bent regions, wherein the two second flat regions and the two second bent regions together wrap the first flat region and the two first bent regions.

[0021] In the embodiments of this application, the electrode assembly adopts a wound structure design. When the large surface (i.e., the front) of the battery cell is subjected to an external force impact, a second separator with low adhesion is provided in the flat area corresponding to the large surface of the electrode assembly. The sliding action between the second separator and the electrode sheet can buffer the external force impact from the large surface. In addition, a second separator with low adhesion can be provided in the bending area. The sliding action between the second separator and the electrode sheet can buffer the external force impact from the side (e.g., the length direction of the battery cell). This helps to further reduce the risk of short circuit when the battery cell is subjected to an external force impact.

[0022] In some embodiments, the number of electrode assemblies is one; the first region includes a first straight region and two first bent regions, and the second region includes two second straight regions and two second bent regions.

[0023] In the embodiments of this application, the case where the number of electrode components is one is specified, and it is clarified that the second region of the electrode component is composed of two second flat regions and two second bent regions. This arrangement allows the battery cell to dissipate energy through the sliding of the second separator and the electrode sheet in the second region when it is impacted in the direction of the flat region and the bent region, which helps to reduce the risk of short circuit when the battery is impacted by external force.

[0024] In some embodiments, the number of electrode assemblies is two, and they are stacked along the thickness direction of the electrode assemblies; the first region includes a first flat region, two first bent regions and a second flat region away from the housing side along the thickness direction, and the second region includes a second flat region and two second bent regions along the thickness direction close to the housing side.

[0025] In the embodiments of this application, the case where the number of electrode assemblies is two is defined, and the second region of each electrode assembly is composed of a second flat region near the casing and two second bent regions. This configuration allows the battery cell to dissipate energy through the sliding of the second separator and the electrode sheet in the second region when it is impacted towards the flat region and the bent region, which helps to reduce the risk of short circuit when the battery is subjected to external impact. In addition, the second separator with low adhesion is provided only in the second flat region near the casing, while the first separator with high adhesion is provided in the second flat region away from the casing, which can effectively improve the impact resistance of the battery cell and further improve the structural stability of the electrode assembly.

[0026] In some embodiments, the number of electrode assemblies is two or more, and they are stacked along the thickness direction of the electrode assemblies; wherein, for the electrode assemblies located at both ends, the first region includes a first straight region, two first bent regions, and a second straight region away from the housing side along the thickness direction, and the second region includes a second straight region and two second bent regions along the thickness direction closer to the housing side; for the electrode assembly located in the middle, the first region includes a first straight region, two second straight regions, and two first bent regions, and the second region includes two second bent regions.

[0027] In the embodiments of this application, the case where there are two or more electrode assemblies is defined, and the positions of the second region and the first region of the electrode assemblies located at both ends and the electrode assembly located in the middle are defined. This arrangement allows the battery cell to dissipate energy through the sliding of the second separator and the electrode sheet in the second region when it is impacted towards the flat region and the bending region, which helps to reduce the risk of short circuit when the battery is impacted by external force. In addition, for the electrode assemblies located at both ends, a second separator with low adhesion is provided only in the second flat region near the shell, while a first separator with high adhesion is provided in the second flat region away from the shell. This can effectively improve the impact resistance of the battery cell and further improve the structural stability of the electrode assembly. For the electrode assembly located in the middle, since only two second bending regions are in adjacent contact with the shell, a second separator with low adhesion is provided only in the two second bending regions adjacent to the shell, while a first separator with high adhesion is provided in the other regions. This can also effectively improve the impact resistance of the battery cell and further improve the structural stability of the electrode assembly.

[0028] In some embodiments, the diaphragm further includes a buffer layer disposed on at least one side of the base membrane, the buffer layer comprising a plurality of spaced sheet-like particles and an elastic adhesive filling the gaps between the sheet-like particles.

[0029] In the embodiments of this application, by setting sheet-like particles in the buffer layer and an elastic binder filling between the sheet-like particles, an energy dissipation network with dynamic response capability can be formed: When a battery cell is impacted by an external force, the sheet-like particles in the buffer layer will slide relative to each other under the action of mechanical stress. Through the dissipation of impact energy during the sliding process, the magnitude of impact energy directly transmitted to the electrode is effectively reduced, thereby reducing the risk of brittle cracking of the electrode due to stress concentration, and thus reducing the risk of short circuit when the battery cell is impacted by an external force; In addition, the elastic binder filling between the sheet-like particles will undergo elastic deformation during the particle sliding process and under the compression of external force, and the impact energy can be further dissipated through this elastic deformation; After the impact ends, the elastic recovery force of the elastic binder can drive the sheet-like particles to partially rebound to the initial position, maintaining the structural integrity of the buffer layer, so that the buffer layer can continuously resist subsequent external force impacts, thereby further reducing the risk of short circuit when the battery cell is impacted by multiple external forces.

[0030] In some embodiments, the thickness of the first diaphragm is H1, and the thickness of the second diaphragm is H2, where H2 > H1.

[0031] In the embodiments of this application, the casing serves as the direct interface for the battery cell to withstand external impacts. When the battery cell is subjected to an external impact, the impact energy is easily transferred through the casing to the adjacent electrode assembly area (i.e., the second region). By providing a second separator with a larger thickness in the second region—that is, the second separator has higher mechanical strength and deformation volume—when the battery cell is subjected to an external impact, the second separator can more effectively resist and absorb the impact energy with its own strength and deformation capacity, thereby reducing the direct transfer of impact energy to the interior. This design can further reduce the probability of brittle cracking of the electrode due to impact, thereby reducing the risk of short circuit in the battery cell. In addition, providing a thinner first separator in the first region with a lower impact risk can retain higher ion transport efficiency and volumetric energy density, which is beneficial for maintaining good electrochemical performance of the battery cell.

[0032] A second aspect of this application provides a battery device including the battery cell provided in the first aspect. The battery device provided in this application, by including the battery cell provided in the first aspect, possesses at least the same advantages as the battery cell provided in the first aspect.

[0033] A third aspect of this application provides an electrical device that includes the battery device provided in the second aspect. The electrical device provided in this application, since it also includes the battery cell provided in the first aspect, possesses at least the same advantages as the battery cell provided in the first aspect. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of the electrical equipment provided in the embodiments of this application;

[0036] Figure 2 This is an exploded view of the battery device provided in the embodiments of this application;

[0037] Figure 3 This is an exploded structural diagram of a battery cell provided in an embodiment of this application;

[0038] Figure 4 This is a schematic diagram of the structure of the first embodiment of the electrode assembly provided in this application;

[0039] Figure 5 This is a schematic diagram of the structure of the second embodiment of the electrode assembly provided in this application;

[0040] Figure 6 yes Figure 5 A schematic diagram showing the division of the straight and bent regions of the electrode assembly;

[0041] Figure 7 This is a schematic diagram of the structure of two electrode assemblies stacked according to an embodiment of this application;

[0042] Figure 8 This is a schematic diagram of the structure of the three electrode components stacked according to the embodiments of this application;

[0043] Figure 9 This is a schematic diagram of the diaphragm provided in the embodiments of this application.

[0044] Explanation of key figure labels:

[0045] Electrical equipment 1000; battery device 100; controller 200; motor 300; housing 10; first part 11; second part 12; battery cell 20; end cap 21; electrode terminal 21a; housing 22; electrode assembly 23; first region 23a; second region 23b; tab 23c; electrode 231; positive electrode 231a; negative electrode 231b; separator 232; first separator 232a; second separator 232b; base film 232c; buffer layer 232d; sheet particles 232e; elastic adhesive 232f; flat region 233; first flat region 233a; second flat region 233b; bending region 234; first bending region 234a; second bending region 234b. Detailed Implementation

[0046] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0047] The terms "first," "second," and "third" in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0048] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0049] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0050] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0051] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0052] In related technologies, battery cells contain electrode assemblies, which typically include a positive electrode, a negative electrode, and a separator between the positive and negative electrodes. The separator serves two purposes: ion conduction and electronic insulation; and separating the positive and negative electrodes to prevent direct contact and short circuits. However, when a battery cell is subjected to strong external impacts (such as collisions, compression, or punctures), the electrode near the impact area may fracture brittlely, causing particles to detach and burrs to form. These detached particles and burrs can easily puncture the separator, allowing the positive and negative electrodes to come into direct contact, triggering an internal short circuit within the battery cell. This can ultimately lead to safety issues such as fires and explosions. Therefore, reducing the risk of short circuits in battery cells under external impact is a pressing technical problem that needs to be solved.

[0053] To further reduce the risk of short circuits when battery cells are subjected to external impacts, research has found that by reducing the adhesive force of the separator in the second region of the electrode assembly, the electrode assembly closer to the impact area (i.e., the separator and the electrode in the second region) can dissipate the impact energy when the battery cell is subjected to an external impact. This reduces the risk of the electrode cracking and puncturing the separator, leading to a short circuit, and is beneficial to improving the safety performance of the battery cell.

[0054] It should be noted that, unless otherwise specified, the battery mentioned in the embodiments of this application can refer to a single battery cell or a battery assembly. A single battery cell can be used, but is not limited to, in electrical equipment such as vehicles, ships, or aircraft. The power system of such electrical equipment can be composed of battery cells and battery assemblies disclosed in this application.

[0055] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0056] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device according to an embodiment of this application.

[0057] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of an electrical device 1000 provided in an embodiment of this application. The electrical device 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is internally provided in the electrical device 1000, and the battery device 100 can be located at the bottom, head, or tail of the electrical device 1000. The battery device 100 can be used to supply power to the electrical device 1000; for example, the battery device 100 can serve as the operating power source for the electrical device 1000. The electrical device 100 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the electrical device 1000 during startup, navigation, and driving.

[0058] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the electrical equipment 1000, but also as the driving power source for the electrical equipment 1000, replacing or partially replacing fuel oil or natural gas to provide driving power for the electrical equipment 1000.

[0059] Please refer to Figure 2 , Figure 2This is an exploded structural diagram of the battery device 100 provided in an embodiment of this application. The battery device 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, jointly defining a space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 jointly define the space. Alternatively, the first portion 11 and the second portion 12 may both be hollow structures with one open side, with the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a cuboid, etc.

[0060] In the battery device 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also be composed of multiple battery cells 20 first connected in series, parallel, or in a mixed manner to form battery device 100 modules, which are then connected in series, parallel, or in a mixed manner to form a whole and housed within the housing 10. The battery device 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0061] Each battery cell 20 can be a secondary battery or a primary battery, and can also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited to these.

[0062] Please refer to Figure 3 , Figure 3 This is an exploded structural diagram of the battery cell 20 provided in an embodiment of this application. The battery cell 20 refers to the smallest unit that makes up the battery device 100. The battery cell 20 may include a housing 22. This outer packaging can be used to encapsulate the electrode assembly 23 and the electrolyte. The outer packaging includes an end cap 21, a housing 22, and other functional components.

[0063] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 21 is not easily deformed under pressure and impact, giving battery cell 20 higher structural strength and improved stability. Functional components such as electrode terminals 21a can be provided on end cap 21. Electrode terminals 21a can be used for electrical connection with electrode assembly 23 to output or input electrical energy to battery cell 20. In some embodiments, end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of battery cell 20 reaches a threshold. The material of end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating element (not shown) may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0064] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 closes the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and the housing 22 can be integrated. Specifically, the end cap 21 and the housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the end cap 21 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The housing 22 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0065] Electrode assembly 23 is the component in the battery cell 20 where electrochemical reactions occur. The casing 22 may contain one or more electrode assemblies 23. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets without active material each constitute tabs 23c. The positive and negative tabs may be located together at one end of the main body or at opposite ends of the main body. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs 23c connect to the electrode terminals to form a current loop.

[0066] According to some embodiments of this application, refer to Figure 3 Please refer to further details. Figures 4 to 5 , Figure 4 This is a schematic diagram of the structure of the electrode assembly 23 according to the first embodiment of this application. Figure 5 This is a schematic diagram of the structure of the electrode assembly 23 in the second embodiment of the present application. In the first aspect of the present application, a battery cell 20 is provided. The battery cell 20 includes a housing 22 and one or more electrode assemblies 23. The electrode assembly 23 is housed in the housing 22 and includes an electrode 231 and a separator 232 disposed between the electrode 231. The separator 232 includes a first separator 232a and a second separator 232b. The electrode assembly 23 includes a first region 23a and a second region 23b. The second region 23b is disposed close to the housing 22 relative to the first region 23a. The first separator 232a is located in the first region 23a, and the second separator 232b is located in the second region 23b. The adhesion force between the first separator 232a and the electrode 231 is F1, and the adhesion force between the second separator 232b and the electrode 231 is F2, where F1 > F2 and F2 ≤ 10 N / m.

[0067] In the embodiments of this application, adhesive force is common knowledge in the art and has a known meaning in the art; it can be measured by methods and instruments in the art. Exemplarily, the value of F2 can be 0 N / m, 1 N / m, 2 N / m, 4 N / m, 6 N / m, 8 N / m, 10 N / m, etc., or a range consisting of any two of the above values, for example, 0 N / m ≤ F2 ≤ 2 N / m, 2 N / m ≤ F2 ≤ 6 N / m, 6 N / m ≤ F2 ≤ 10 N / m, etc. When the value of F2 is, for example, 2 N / m, the value of F1 can be 3 N / m, 4 N / m, 5 N / m, 7 N / m, 9 N / m, 13 N / m, 15 N / m, 20 N / m, etc.

[0068] It should be noted that the orientation described in the embodiments of this application is specifically taken as the reference orientation when the battery cell 20 is placed on a flat platform with its end cap 21 on top, such as... Figure 3 As shown, the vertical direction represents the height of the battery cell 20. Within the plane of the end cap 21, the arrangement direction of the positive and negative electrode terminals represents the length direction of the battery cell 20 (direction CD in the attached figure). The direction perpendicular to the length direction represents the thickness direction of the battery cell 20, which is also the thickness direction of the electrode assembly 23 (direction AB in the attached figure). The height, thickness, and length directions of the battery cell 20 are mutually perpendicular.

[0069] The electrode assembly 23 provided in this application embodiment has a structure including but not limited to a stacked core structure formed by alternating stacking of multiple positive electrode plates 231a and multiple negative electrode plates 231b (e.g., ...). Figure 4As shown), and a wound core structure formed by winding the positive electrode 231a and the negative electrode 231b (as shown). Figure 5 (As shown). The housing 22 may house only one electrode assembly 23 or multiple electrode assemblies 23, which can be configured according to actual needs by those skilled in the art.

[0070] In the technical solution of this application embodiment, by setting the second separator 232b in the second region 23b near the housing 22 and adjusting its adhesion force to a specific range, when the battery cell 20 is subjected to an external impact, the low adhesion force between the second separator 232b and the electrode 231 allows for a certain degree of interface slippage under the impact force. This slippage process can dissipate some of the impact energy through interface friction loss, reducing the amount of impact energy directly transferred to the electrode 231, thereby reducing the risk of brittle cracking of the electrode 231 due to stress concentration, and thus reducing the probability of short circuit when the battery cell 20 is subjected to an external impact. In addition, by setting the first separator 232a to have a higher adhesion force relative to the second separator 232b, the structural stability of the electrode assembly 23 can be effectively maintained, reducing the adverse effects on the performance of the battery cell 20 caused by insufficient adhesion force of the separator 232.

[0071] Understandably, this design effectively mitigates the stress concentration effect caused by the high adhesion between the traditional diaphragm 232 and electrode 231 under external impact. When the diaphragm 232 and electrode 231 are strongly bonded, external stress can easily act directly on the electrode 231 through this rigid connection, causing the active material layer or current collector to crack due to stress overload. The introduction of a low adhesion interface allows some of the impact energy to be absorbed during the interface sliding process, thereby significantly reducing the risk of electrode 231 cracking and thus reducing the safety hazard of short circuits caused by electrode 231 breaking and puncturing the diaphragm 232.

[0072] In some embodiments, such as Figure 4 As shown, the electrode assembly 23 has a stacked structure, and the second region 23b is located on opposite sides of the first region 23a along the thickness direction of the electrode assembly 23.

[0073] In the embodiments of this application, the second region 23b is disposed on both sides of the first region 23a along the thickness direction of the electrode assembly 23. That is, the second region 23b is closer to the housing 22 in the thickness direction than the first region 23a. When the battery cell 20 is impacted by an external force from the thickness direction, the impact can be buffered by the sliding action between the second separator 232b of the second region 23b and the electrode 231, thereby helping to reduce the risk of short circuit when the battery cell 20 is impacted by an external force.

[0074] In some embodiments, 5N / m≤F1-F2≤19N / m.

[0075] For example, the values ​​of F1-F2 can be 5N / m, 7N / m, 9N / m, 12N / m, 15N / m, 17N / m, 19N / m, etc., or a range consisting of any two of the above values, such as 5N / m≤F1-F2≤9N / m, 9N / m≤F1-F2≤15N / m, 15N / m≤F1-F2≤19N / m, etc.

[0076] In the embodiments of this application, by limiting the difference between F1 and F2 to the above range, when the battery cell 20 is subjected to an impact, it can effectively dissipate the impact energy through the slippage between the second separator 232b and the electrode 231, and maintain the structural stability of the electrode assembly 23 through the high adhesion of the first separator 232a, thereby achieving a balance between safety and reliability in the battery cell 20.

[0077] In some embodiments, 15 N / m ≤ F1 ≤ 25 N / m; and / or, 6 N / m ≤ F2 ≤ 10 N / m.

[0078] For example, the value of F1 can be 15 N / m, 17 N / m, 19 N / m, 21 N / m, 22 N / m, 24 N / m, 25 N / m, etc., or a range consisting of any two of the above values, such as 15 N / m ≤ F1 ≤ 19 N / m, 19 N / m ≤ F1 ≤ 22 N / m, 22 N / m ≤ F1 ≤ 25 N / m, etc. The value of F2 can be 6 N / m, 6.5 N / m, 7 N / m, 8 N / m, 8.5 N / m, 9 N / m, 10 N / m, etc., or a range consisting of any two of the above values, such as 6 N / m ≤ F2 ≤ 7 N / m, 7 N / m ≤ F2 ≤ 8 N / m, 8 N / m ≤ F2 ≤ 10 N / m, etc.

[0079] In the embodiments of this application, by further limiting the values ​​of F1 and F2 to the above range, when the battery cell 20 is subjected to an impact, it can effectively dissipate the impact energy through the slippage of the second separator 232b, and maintain the structural stability of the electrode assembly 23 through the high adhesion of the first separator 232a, thereby achieving a balance between safety and reliability in the battery cell 20.

[0080] In some embodiments, the diaphragm 232 includes a base membrane 232c and an adhesive coating disposed on at least one side of the base membrane 232c. The adhesive coating includes one of polyvinylidene fluoride, polyacrylic acid, polymethyl methacrylate, polybutyl acrylate, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyurethane.

[0081] In the embodiments of this application, by defining the specific structure of the separator 232 and the selection of the adhesive coating material, it is beneficial to further optimize the stability and electrochemical performance of the battery cell 20.

[0082] In some embodiments, the areal density of the adhesive coating on the first diaphragm 232a is M1, and the areal density of the adhesive coating on the second diaphragm 232b is M2, where 0.01 ≤ M2 / M1 ≤ 0.4.

[0083] In the embodiments of this application, areal density is common knowledge in the art and has a known meaning in the art; it can be measured by methods and instruments in the art. For example, the value of M2 / M1 can be 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, etc., or a range consisting of any two of the above values, such as 0.01≤M2 / M1≤0.1, 0.1≤M2 / M1≤0.2, 0.2≤M2 / M1≤0.4, etc.

[0084] In the embodiments of this application, by limiting the ratio of M2 to M1 within the above-mentioned range, the adhesive coating of the second diaphragm 232b can have a minimum necessary thickness, which maintains the basic adhesive force to reduce the possibility of delamination between the electrode 231 and the second diaphragm 232b, and achieves a lower adhesive force by having a significantly lower areal density than the first diaphragm 232a, so as to meet the slippage requirements between the second diaphragm 232b and the electrode 231 in the event of an impact.

[0085] In some embodiments, 0.09 mg / cm 2 ≤M1≤0.13mg / cm 2 ; and / or, 0.02 mg / cm 2 ≤M2≤0.05mg / cm 2 .

[0086] For example, the value of M1 can be 0.09 mg / cm³. 2 0.1 mg / cm 2 0.11 mg / cm 2 0.115 mg / cm 2 0.12 mg / cm 2 0.125 mg / cm 2 0.13 mg / cm 2 etc., or a range consisting of any two of the above values, for example, 0.09 mg / cm³. 2 ≤M1≤0.11mg / cm 2 0.11 mg / cm 2 ≤M1≤0.12mg / cm 2 0.12 mg / cm 2 ≤M1≤0.13mg / cm 2 The value of M2 can be 0.02 mg / cm³. 2 0.025 mg / cm 2 0.03 mg / cm2 0.035 mg / cm 2 0.04 mg / cm 2 0.045 mg / cm 2 0.05 mg / cm 2 etc., or a range consisting of any two of the above values, for example, 0.02 mg / cm³. 2 ≤M2≤0.03mg / cm 2 0.03 mg / cm 2 ≤M2≤0.04mg / cm 2 0.04 mg / cm 2 ≤M2≤0.05mg / cm 2 wait.

[0087] In the embodiments of this application, by further limiting the values ​​of M2 and M1 to the aforementioned range, the adhesive coating of the second diaphragm 232b can have a minimum necessary thickness. This maintains basic adhesive strength to reduce the possibility of delamination between the electrode 231 and the second diaphragm 232b, while achieving lower adhesive strength through a significantly lower areal density than the first diaphragm 232a, thus meeting the slippage requirements between the second diaphragm 232b and the electrode 231 in the event of an impact. Furthermore, a value of M1 within the aforementioned range can provide stronger adhesive strength to the first diaphragm 232a, which is beneficial for maintaining the structural stability of the electrode assembly 23.

[0088] In some embodiments, the areal density of the adhesive coating gradually increases in the direction from the second region 23b toward the first region 23a, and / or the areal density of the adhesive coating gradually increases in the first diaphragm 232a.

[0089] In the embodiments of this application, by defining the direction along the second region 23b toward the first region 23a, the areal density of the adhesive coating of the second separator 232b and / or the first separator 232a gradually increases, so that the difference in adhesive force is achieved through a continuous transition rather than a step change. This design can reduce the risk of delamination or tearing caused by a sudden increase in stress at the junction of different regions. In addition, when the battery cell 20 is impacted, the second region 23b, which is closer to the casing 22, preferentially slides and dissipates energy due to the lowest areal density of the adhesive coating, while the areal density gradually increases toward the first region 23a, so that the remaining impact energy is gradually absorbed by the region with higher adhesive force. This gradient energy dissipation mechanism can not only fully release the impact energy, but also reduce the possibility of excessive displacement or misalignment between the electrode 231 and the separator 232, which is beneficial to reducing the risk of short circuit in the battery cell 20.

[0090] In some embodiments, the thickness of the second region 23b along the thickness direction of the electrode assembly 23 is 10% to 30% of the thickness of the electrode assembly 23.

[0091] For example, the thickness of the second region 23b as a percentage of the thickness of the electrode assembly 23 can be 10%, 13%, 16%, 19%, 22%, 25%, 30%, etc., or a range of any two of the above values, such as 10% to 16%, 16% to 22%, 22% to 30%, etc.

[0092] In the embodiments of this application, by limiting the thickness of the second region 23b to the above range, on the one hand, the second region 23b has sufficient thickness so that it can dissipate the impact energy fully through the sliding of the second diaphragm 232b when subjected to external impact; on the other hand, by limiting the upper limit of the proportion of the second region 23b, the risk of the electrode assembly 23 becoming loose due to insufficient bonding strength can be reduced.

[0093] In some embodiments, please refer to Figure 6 , Figure 6 yes Figure 5 The diagram shows the division of the flat region 233 and the bent region 234 of the electrode assembly 23. The electrode assembly 23 has a wound structure, which includes a flat region 233 and a bent region 234. The flat region 233 includes a first flat region 233a and two second flat regions 233b. The bent region 234 includes two first bent regions 234a and two second bent regions 234b. The two second flat regions 233b and the two second bent regions 234b together wrap the first flat region 233a and the two first bent regions 234a.

[0094] In the embodiments of this application, the electrode assembly 23 adopts a wound structure design. When the large surface (i.e. the front) of the battery cell 20 is subjected to an external force impact, a second separator 232b with low adhesion is provided in the flat area 233 corresponding to the large surface of the electrode assembly 23. The sliding action between the second separator 232b and the electrode 231 can buffer the external force impact from the large surface. In addition, a second separator 232b with low adhesion is provided in the bending area 234. The sliding action between the second separator 232b and the electrode 231 can buffer the external force impact from the side direction (e.g., the length direction of the battery cell 20), thereby further reducing the risk of short circuit when the battery cell 20 is subjected to an external force impact.

[0095] In some embodiments, such as Figure 6 As shown, the number of electrode components 23 is one; the first region 23a includes a first straight region 233a and two first bending regions 234a, and the second region 23b includes two second straight regions 233b and two second bending regions 234b.

[0096] In the embodiments of this application, the case where the number of electrode components 23 is one is specified, and it is clarified that the second region 23b of the electrode component 23 is composed of two second straight regions 233b and two second bent regions 234b. This arrangement allows the battery cell 20 to dissipate energy through the sliding of the second separator 232b and the electrode 231 in the second region 23b when it is impacted in the direction of the straight region 233 and the bent region 234, which helps to reduce the risk of short circuit when the battery is impacted by external force.

[0097] In some embodiments, please refer to Figure 7 , Figure 7 This is a schematic diagram of the structure of two electrode components 23 stacked in an embodiment of this application. There are two electrode components 23, which are stacked along the thickness direction of the electrode components 23. The first region 23a includes a first flat region 233a, two first bending regions 234a and a second flat region 233b along the thickness direction away from the housing 22. The second region 23b includes a second flat region 233b along the thickness direction close to the housing 22 and two second bending regions 234b.

[0098] In the embodiments of this application, the number of electrode assemblies 23 is limited to two, and the second region 23b of each electrode assembly 23 is configured to consist of a second flat region 233b near the housing 22 and two second bent regions 234b. This configuration allows the battery cell 20 to dissipate energy through the sliding of the second separator 232b and the electrode 231 in the second region 23b when subjected to impacts towards the flat region 233 and the bent region 234, thus helping to reduce the risk of short circuits when the battery is subjected to external impacts. Furthermore, by providing a second separator 232b with low adhesion only in the second flat region 233b near the housing 22, and a first separator 232a with high adhesion in the second flat region 233b away from the housing 22, the impact resistance of the battery cell 20 can be effectively improved, while the structural stability of the electrode assembly 23 can be further enhanced.

[0099] In some embodiments, please refer to Figure 8 , Figure 8This is a schematic diagram of the structure of three electrode components 23 stacked according to an embodiment of this application, that is, the number of electrode components 23 is two or more, and they are stacked along the thickness direction of the electrode components 23; wherein, for the electrode components 23 located at both ends, the first region 23a includes a first straight region 233a, two first bending regions 234a and a second straight region 233b along the thickness direction away from the housing 22, and the second region 23b includes a second straight region 233b along the thickness direction close to the housing 22 and two second bending regions 234b; for the electrode component 23 located in the middle, the first region 23a includes a first straight region 233a, two second straight regions 233b and two first bending regions 234a, and the second region 23b includes two second bending regions 234b.

[0100] For example, the number of electrode assemblies 23 can also be 4, 5, 6, 7, 8, 10, etc., which can be set according to actual needs by those skilled in the art.

[0101] In the embodiments of this application, the case where there are two or more electrode assemblies 23 is defined, and the positions of the second region 23b and the first region 23a of the electrode assemblies 23 located at both ends and the electrode assembly 23 located in the middle are defined. This arrangement allows the battery cell 20 to dissipate energy through the sliding of the second separator 232b and the electrode 231 in the second region 23b when it is impacted in the direction of the flat region 233 and the bending region 234, which helps to reduce the risk of short circuit when the battery is impacted by external force. In addition, for the electrode assemblies 23 located at both ends, the second separator 232b with low adhesion is provided only in the second flat region 233b on the side closer to the housing 22, while the first separator 232a with high adhesion is provided in the second flat region 233b on the side farther from the housing 22. This can effectively improve the impact resistance of the battery cell 20 and further improve the structural stability of the electrode assembly 23. For the electrode assembly 23 located in the middle, since only two second bending areas 234b are in adjacent contact with the housing 22, a second separator 232b with low adhesion is provided only in the two second bending areas 234b adjacent to the housing 22, while a first separator 232a with high adhesion is provided in other areas. This can effectively improve the impact resistance of the battery cell 20 and further improve the structural stability of the electrode assembly 23.

[0102] In some embodiments, please refer to Figure 9 , Figure 9 This is a schematic diagram of the structure of the diaphragm 232 provided in the embodiment of this application. The diaphragm 232 also includes a buffer layer 232d disposed on at least one side of the base membrane 232c. The buffer layer 232d includes a plurality of spaced sheet-like particles 232e and an elastic adhesive 232f filling the gaps between the sheet-like particles 232e.

[0103] The sheet-like particles 232e of this application embodiment are different from fibrous, spherical or block particles, and have significant two-dimensional planar features. They are a thin sheet-like entity. The elastic adhesive 232f is a type of functional material that combines adhesive properties and elastic deformation capabilities. Its core characteristic is that it can withstand mechanical stresses such as tension, compression and bending within a certain range and undergo reversible deformation, while maintaining adhesion to the substrate.

[0104] In the embodiments of this application, by providing sheet-like particles 232e in the buffer layer 232d and an elastic adhesive 232f filling the spaces between the sheet-like particles 232e, an energy dissipation network with dynamic response capability can be formed. When the battery cell 20 is subjected to an external impact, the sheet-like particles 232e in the buffer layer 232d will slide relative to each other under the action of mechanical stress. Through the dissipation of impact energy during the sliding process, the magnitude of the impact energy directly transmitted to the electrode 231 is effectively reduced, thereby reducing the risk of brittle cracking of the electrode 231 due to stress concentration, and thus reducing the risk of battery cell brittle cracking. The risk of short circuit when subjected to external impact is reduced. In addition, the elastic binder 232f filled between the sheet particles 232e undergoes elastic deformation during particle sliding and under external pressure, which can further dissipate impact energy. After the impact ends, the elastic restoring force of the elastic binder 232f can drive the sheet particles 232e to partially rebound to their initial position, maintaining the structural integrity of the buffer layer 232d, so that the buffer layer 232d can continuously resist subsequent external impacts, thereby further reducing the risk of short circuit in the battery cell 20 under multiple external impacts.

[0105] Optionally, the flaky particles 232e include one of boehmite, alumina, silicon dioxide, magnesium oxide, titanium dioxide, tin oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, and calcium carbonate; the elastic adhesive 232f includes one of polyurethane, epoxy resin, polyvinyl alcohol, chitosan, silk protein, polyacrylamide, polydimethylsiloxane, and sodium carboxymethyl cellulose.

[0106] In some embodiments, the thickness of the first diaphragm 232a is H1, and the thickness of the second diaphragm 232b is H2, where H2 > H1.

[0107] In the embodiments of this application, the thicknesses of the first diaphragm 232a and the second diaphragm 232b are common knowledge in the art and have a common meaning in the art, and can be measured by methods and instruments in the art. For example, the thickness data at multiple locations can be obtained by measuring with a micrometer at multiple different positions of the diaphragm 232, and the average value is finally taken as the thickness of the diaphragm 232.

[0108] In the embodiments of this application, the casing 22 serves as the direct interface for the battery cell 20 to withstand external impacts. When the battery cell 20 is subjected to an external impact, the impact energy is easily transferred through the casing 22 to the adjacent electrode assembly region (i.e., the second region 23b). By providing a second separator 232b with a larger thickness in the second region 23b, i.e., the second separator 232b has higher mechanical strength and deformation volume, when the battery cell 20 is subjected to an external impact, the second separator 232b can more effectively resist and absorb the impact energy with its own strength and deformation capacity, thereby reducing the direct transfer of impact energy to the interior. This design can further reduce the probability of brittle cracking of the electrode 231 due to impact, thereby reducing the risk of short circuit in the battery cell 20. In addition, providing a thinner first separator 232a in the first region 23a, where the impact risk is lower, can retain higher ion transport efficiency and volumetric energy density, thereby helping to maintain good electrochemical performance of the battery cell 20.

[0109] In some embodiments, the diaphragm 232 further includes a ceramic coating disposed between the base membrane 232c and the adhesive coating.

[0110] In the embodiments of this application, by providing a ceramic coating, the mechanical strength of the separator 232 can be improved, thereby effectively reducing the risk of the separator 232 being punctured, which is beneficial to reducing the probability of short circuit of the battery cell 20.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, include: case; One or more electrode assemblies are housed within the housing. Each electrode assembly includes an electrode sheet and a diaphragm disposed between the electrode sheets. The diaphragm includes a first diaphragm and a second diaphragm. The electrode assembly includes a first region and a second region, with the second region disposed close to the housing relative to the first region. The first diaphragm is located in the first region, and the second diaphragm is located in the second region. The adhesive force between the first diaphragm and the electrode sheet is F1, and the adhesive force between the second diaphragm and the electrode sheet is F2, where F1 > F2 and F2 ≤ 10 N / m.

2. The battery cell according to claim 1, characterized in that, 5N / m≤F1-F2≤19N / m.

3. The battery cell according to claim 1, characterized in that, 15 N / m ≤ F1 ≤ 25 N / m; and / or, 6 N / m ≤ F2 ≤ 10 N / m.

4. The battery cell according to claim 1, characterized in that, The diaphragm includes a base membrane and an adhesive coating disposed on at least one side of the base membrane. The adhesive coating includes one of polyvinylidene fluoride, polyacrylic acid, polymethyl methacrylate, polybutyl acrylate, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyurethane.

5. The battery cell according to claim 4, characterized in that, The areal density of the adhesive coating on the first diaphragm is M1, and the areal density of the adhesive coating on the second diaphragm is M2, where 0.01 ≤ M2 / M1 ≤ 0.

4.

6. The battery cell according to claim 5, characterized in that, 0.09 mg / cm 2 ≤M1≤0.13mg / cm 2 ; and / or, 0.02 mg / cm 2 ≤M2≤0.05mg / cm 2 .

7. The battery cell according to claim 4, characterized in that, Along the direction from the second region toward the first region, the areal density of the adhesive coating on the second diaphragm gradually increases, and / or the areal density of the adhesive coating on the first diaphragm gradually increases.

8. The battery cell according to claim 1, characterized in that, Along the thickness direction of the electrode assembly, the thickness of the second region accounts for 10% to 30% of the thickness of the electrode assembly.

9. The battery cell according to claim 1, characterized in that, The electrode assembly is a wound structure, which includes a straight region and a bent region. The straight region includes a first straight region and two second straight regions, and the bent region includes two first bent regions and two second bent regions. The two second straight regions and the two second bent regions together wrap the first straight region and the two first bent regions.

10. The battery cell according to claim 9, characterized in that, The number of electrode components is one; The first region includes the first straight area and two first bend areas, and the second region includes two second straight areas and two second bend areas.

11. The battery cell according to claim 9, characterized in that, The number of electrode assemblies is two, and they are stacked along the thickness direction of the electrode assemblies; The first region includes a first straight region, two first bending regions, and a second straight region along the thickness direction away from the side of the housing. The second region includes a second straight region along the thickness direction close to the side of the housing and two second bending regions.

12. The battery cell according to claim 9, characterized in that, The number of electrode assemblies is two or more, and they are stacked along the thickness direction of the electrode assemblies; Wherein, for the electrode assembly located at both ends, the first region includes the first straight region, two first bending regions and a second straight region away from the housing along the thickness direction, and the second region includes the second straight region and two second bending regions along the thickness direction close to the housing. For the electrode assembly located in the middle, the first region includes a first flat region, two second flat regions and two first bent regions, and the second region includes two second bent regions.

13. The battery cell according to any one of claims 4 to 7, characterized in that, The diaphragm further includes a buffer layer disposed on at least one side of the base membrane, the buffer layer comprising a plurality of spaced sheet-like particles and an elastic adhesive filling the gaps between the sheet-like particles.

14. The battery cell according to any one of claims 2 to 12, characterized in that, The thickness of the first diaphragm is H1, and the thickness of the second diaphragm is H2, where H2 > H1.

15. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1 to 14.

16. An electrical appliance, characterized in that, Includes the battery device as described in claim 15.

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