Battery cell, battery device, and electric device

Abstract

The application provides a battery monomer, a battery device and a power utilization equipment. The battery monomer comprises an electrode assembly and a shell, the electrode assembly is accommodated in the shell, and the electrode assembly comprises a pole piece and a diaphragm arranged between the pole pieces. The diaphragm comprises a base film and a buffer layer arranged on at least one side of the base film, the buffer layer comprises a plurality of sheet-shaped particles distributed at intervals and an elastic adhesive filled in the gaps between the sheet-shaped particles. According to the application, the buffer layer is arranged on the diaphragm, so that when the battery monomer is subjected to external force impact, the impact energy can be dissipated through the sliding of the sheet-shaped particles and the elastic deformation of the elastic adhesive, thereby reducing the risk of short circuit of the battery monomer.

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 internal electrode plates 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 fires and explosions. 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 solve the above-mentioned technical problems, in a first aspect of this application, a battery cell is provided. The battery cell includes an electrode assembly and a housing. The electrode assembly is housed within the housing. The electrode assembly includes electrode sheets and a separator disposed between the electrode sheets. The separator includes a base film and a buffer layer disposed on at least one side of the base film. The buffer layer includes a plurality of spaced sheet-like particles and an elastic adhesive filling the gaps between the sheet-like particles.

[0005] In the technical solution of this application embodiment, 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.

[0006] In some embodiments, the thickness of the sheet-like particles is 0.3 μm to 0.6 μm.

[0007] In the embodiments of this application, by limiting the thickness of the sheet-like particles within the above-mentioned range, on the one hand, the sheet-like particles have sufficient structural strength, reducing the breakage caused by insufficient strength and affecting the relative sliding between the sheet-like particles; on the other hand, it can prevent the overall thickness of the buffer layer from being too thick due to the excessive thickness of the sheet-like particles, thereby reducing the adverse effects on the electrochemical performance of the battery cells.

[0008] In some embodiments, the volume average particle size Dv50 of the flaky particles is 0.5 μm to 1 μm.

[0009] In the embodiments of this application, by limiting the volume average particle size Dv50 of the sheet-like particles to the above-mentioned range, on the one hand, the sheet-like particles have suitable planar dimensions and can form a flat geometric shape, thereby enabling orderly stacking in the buffer layer and facilitating relative sliding of the sheet-like particles under external force; on the other hand, it can prevent the overall thickness of the buffer layer from being too thick due to excessively large sheet-like particles, thereby reducing the adverse effects on the electrochemical performance of the battery cells.

[0010] In some embodiments, the flaky particles include one of boehmite, alumina, silicon oxide, magnesium oxide, titanium oxide, tin oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, and calcium carbonate.

[0011] In the embodiments of this application, by limiting the material of the sheet-like particles to the aforementioned highly stable inorganic non-metallic or ceramic materials, the sheet-like particles can exist stably in the electrolyte, reducing the probability of degradation or side reactions. At the same time, such materials usually also have high strength characteristics, making the sheet-like particles less prone to breakage under impact loads, and can effectively dissipate impact energy through relative sliding between particles, thereby further reducing the risk of short circuits when the battery cell is subjected to external impact.

[0012] In some embodiments, the volume average particle size Dv50 of the elastic adhesive is 0.05 μm to 0.2 μm.

[0013] In the embodiments of this application, by limiting the volume average particle size Dv50 of the elastic adhesive within the above-mentioned range, the elastic adhesive can effectively fill the gaps between the sheet-like particles, reducing the probability of uneven filling or clogging.

[0014] In some embodiments, the elastic modulus of the elastic adhesive is 0.3 MPa to 300 MPa.

[0015] In the embodiments of this application, by limiting the elastic modulus of the elastic adhesive within the above-mentioned range, on the one hand, it can effectively support the sheet-like particles, and on the other hand, it can enable the elastic adhesive to have sufficient elastic deformation capability, thereby dissipating some impact energy through tensile deformation, which is beneficial to reducing the risk of short circuit when the battery cell is subjected to external impact.

[0016] In some embodiments, the elastic adhesive includes one of polyurethane, polyvinyl alcohol, chitosan, silk protein, polyacrylamide, polydimethylsiloxane, and sodium carboxymethyl cellulose.

[0017] In the embodiments of this application, by limiting the elastic adhesive to the above-mentioned material, on the one hand, the elastic adhesive has a moderate adhesive strength to prevent the sliding between the sheet-like particles from being hindered due to excessive adhesive force; on the other hand, the above-mentioned material also has a suitable elastic modulus, so that the elastic adhesive can dissipate part of the impact energy through tensile deformation, which is beneficial to reducing the risk of short circuit when the battery cell is subjected to external impact.

[0018] In some embodiments, the mass percentage of the elastic adhesive is 5% to 25% based on the total mass of the buffer layer.

[0019] In the embodiments of this application, by limiting the mass percentage of the elastic adhesive within the above-mentioned range, the elastic adhesive can be distributed in a discrete form within the gaps between the sheet-like particles, forming a point contact network of "sheet-like particles-elastic adhesive-sheet-like particles", reducing gap blockage caused by overfilling; this arrangement allows the sheet-like particles to slide relatively freely, while maintaining the stability of the overall structure of the buffer layer through the contact network.

[0020] In some embodiments, the sheet-like particles have two opposing main surfaces, and the gap size between adjacent sheet-like particles is 0.02 μm to 0.2 μm in a direction perpendicular to the main surfaces, and / or the gap size between adjacent sheet-like particles is 0.1 μm to 1 μm in a direction parallel to the main surfaces.

[0021] In the embodiments of this application, by limiting the gap size between adjacent sheet-like particles in the direction perpendicular or parallel to the main surface to the aforementioned range, suitable sliding freedom can be provided for the sheet-like particles, and the risk of structural collapse caused by excessive gaps can be reduced. It is understood that with gaps formed in the direction perpendicular or parallel to the main surface, when a battery cell is subjected to external impact, the impact energy can be effectively dissipated through the sliding of the sheet-like particles in a direction parallel or close to its main surface, and the impact energy can also be absorbed through the elastic deformation of the elastic adhesive, thereby helping to reduce the risk of short circuits in the battery cell when subjected to external impacts.

[0022] In some embodiments, the thickness of the buffer layer is 1 μm to 6 μm.

[0023] In the embodiments of this application, by limiting the thickness of the buffer layer to the above-mentioned range, on the one hand, the battery cell can effectively resist external impacts through the buffer layer, reducing the risk of short circuit when the battery cell is subjected to external impacts; on the other hand, it can also reduce the adverse effects on the electrochemical performance of the battery cell caused by excessively thick buffer layer.

[0024] In some embodiments, the diaphragm includes a first diaphragm and a second diaphragm, and the electrode assembly includes a first region and a second region, the second region being disposed close to the housing relative to the first region, the first diaphragm being located in the first region, and the second diaphragm being located in the second region; the thickness of the first diaphragm is H1, the thickness of the second diaphragm is H2, and H2 > H1.

[0025] 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—meaning 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 due to its own strength and deformation capacity, thereby reducing the direct transfer of impact energy to the interior. This design can reduce the probability of brittle cracking of the electrode due to impact, thereby reducing the risk of short circuits in the battery cell. Furthermore, providing a thinner first separator in the first region, where the impact risk is lower, can retain higher ion transport efficiency and volumetric energy density, thus helping to maintain good electrochemical performance of the battery cell.

[0026] In some embodiments, the diaphragm includes a first diaphragm and a second diaphragm, the electrode assembly includes a first region and a second region, the second region is 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 adhesion force between the first diaphragm and the electrode is F1, the adhesion force between the second diaphragm and the electrode is F2, F1>F2, F2≤10N / m.

[0027] In the embodiments of this application, by placing the second separator in a second region near the casing and adjusting its adhesive force to a specific range, when the battery cell is subjected to external impact, the low adhesive force between the second separator and the electrode allows for a certain degree of interfacial slippage under the impact force. This slippage process dissipates some of the impact energy through interfacial 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. Furthermore, by setting the first separator to have a higher adhesive 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 separator adhesive force.

[0028] 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.

[0029] 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

[0030] 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.

[0031] Figure 1 This is a schematic diagram of the structure of the electrical equipment provided in the embodiments of this application;

[0032] Figure 2 This is an exploded view of the battery device provided in the embodiments of this application;

[0033] Figure 3 This is an exploded structural diagram of a battery cell provided in an embodiment of this application;

[0034] Figure 4 This is a schematic diagram of the structure of the electrode assembly provided in the embodiments of this application;

[0035] Figure 5 This is a schematic diagram of the diaphragm structure provided in the embodiments of this application;

[0036] Figure 6This is a comparative schematic diagram of the diaphragm provided in the embodiments of this application and a traditional diaphragm under stress;

[0037] Figure 7 This is a scanning electron microscope image of the diaphragm provided in the embodiments of this application;

[0038] Figure 8 yes Figure 4 The diagram shows the division of the first and second regions of the electrode assembly.

[0039] Explanation of key figure labels:

[0040] 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; tab 23a; first region 23b; second region 23c; electrode sheet 231; separator 232; base film 232a; buffer layer 232b; sheet particles 232c; elastic adhesive 232d; first separator 2321; second separator 2322. Detailed Implementation

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0048] Currently, judging from market trends, battery technology is being applied more and more widely. Batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of battery applications, market demand is also constantly increasing.

[0049] In related technologies, a battery cell contains an electrode assembly, which typically includes 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), these forces are directly transmitted to the internal electrodes, causing brittle fracture and resulting in particle detachment and burrs. These detached particles and burrs can easily puncture the separator, allowing direct contact between the positive and negative electrodes, leading to an internal short circuit within the battery cell and potentially causing fires or explosions. Therefore, reducing the risk of short circuits in battery cells under external impact is a pressing technical problem that needs to be solved.

[0050] To further reduce the risk of short circuits when battery cells are subjected to external impacts, research has found that a buffer layer can be set on the separator, and sheet-like particles and elastic adhesives filled between the particles can be placed in the buffer layer. When the battery cell is subjected to external impacts, the impact energy can be dissipated through the sliding of the sheet-like particles and the elastic deformation of the elastic adhesive. This reduces the risk of electrode cracking and puncturing the separator, leading to a short circuit, and is beneficial to improving the safety performance of the battery cell.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of an electrical device 1000 provided in some embodiments 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 power 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.

[0055] 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.

[0056] Please refer to Figure 2 , Figure 2This is an exploded view of a battery device 100 provided in some embodiments 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 accommodating the battery cell 20, and the housing 10 can adopt 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 be of various shapes, such as a cylinder, a cuboid, etc.

[0057] 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.

[0058] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited to these.

[0059] Please refer to Figure 3 , Figure 3 This is an exploded structural diagram of a battery cell 20 provided in some embodiments of this application. The battery cell 20 refers to the smallest unit constituting the battery device 100. The battery cell 20 may include a housing 22. This outer packaging can be used to encapsulate the aforementioned electrode assembly 23 and electrolyte. The outer packaging includes an end cap 21, the housing 22, and other functional components.

[0060] 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.

[0061] 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.

[0062] 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 23a. 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 23a connect to the electrode terminals to form a current loop.

[0063] 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 provided in the embodiments of this application. Figure 5 This is a schematic diagram of the structure of the separator 232 provided in the embodiment of this application. In the first aspect of this application, a battery cell 20 is provided. The battery cell 20 includes an electrode assembly 23 and a housing 22. The electrode assembly 23 is housed in the housing 22. The electrode assembly 23 includes an electrode sheet 231 and a separator 232 disposed between the electrode sheets 231. The separator 232 includes a base film 232a and a buffer layer 232b disposed on at least one side of the base film 232a. The buffer layer 232b includes a plurality of spaced sheet-like particles 232c and an elastic adhesive 232d filling the gaps between the sheet-like particles 232c.

[0064] The electrode assembly 23 provided in this application embodiment has structures including, but not limited to, a stacked core structure formed by alternating stacks of multiple positive and multiple negative electrode sheets, and a wound core structure formed by winding positive and negative electrode sheets. The housing 22 may contain only one electrode assembly 23 or multiple electrode assemblies 23, and those skilled in the art can configure it according to actual needs.

[0065] It should be noted that the orientation described in the embodiments of this application is specifically taken as the orientation when the battery cell 20 is placed on a flat platform with its end cap 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, 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.

[0066] The sheet-like particles 232c 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 232d 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.

[0067] In the technical solution of this application embodiment, by providing sheet-like particles 232c in the buffer layer 232b and an elastic adhesive 232d filling the spaces between the sheet-like particles 232c, 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 232c in the buffer layer 232b 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 battery's energy loss. There is a risk of short circuit when the cell 20 is subjected to external impact. In addition, the elastic binder 232d filled between the sheet particles 232c will undergo elastic deformation during the sliding of the particles and under the compression of external force. This elastic deformation can further dissipate the impact energy. After the impact ends, the elastic restoring force of the elastic binder 232d can drive the sheet particles 232c to partially rebound to the initial position, maintain the structural integrity of the buffer layer 232b, and enable the buffer layer 232b to continuously resist subsequent external impacts, thereby further reducing the risk of short circuit of the battery cell 20 under multiple external impacts.

[0068] Please refer to further details. Figure 6 , Figure 6 This is a comparative schematic diagram of the separator 232 provided in this application embodiment and a conventional separator under stress. The left side of the diagram shows the conventional separator under stress, and the right side shows the separator 232 provided in this application embodiment under stress. The conventional separator mentioned in this application includes a base film and a conventional ceramic coating coated on the surface of the base film. It is understood that since the ceramic particles in the conventional ceramic coating are mostly irregular block particles, the particles interlock due to their sharp edges, forming an overlapping mechanical interlocking structure. When the separator is impacted by external force, the ceramic particles cannot effectively dissipate the impact energy through sliding, but can only directly transfer the external force to the separator and the electrode, resulting in the risk of the separator being penetrated and short-circuiting. However, the separator 232 provided in this application embodiment, due to the presence of a buffer layer 232b, can dissipate the impact of external force through the sliding of the sheet-like particles 232c and the deformation of the elastic adhesive 232d, thereby effectively reducing the risk of short circuit in the battery cell 20 under external force impact.

[0069] For example, the diaphragm 232 of the embodiments of this application can be observed by scanning electron microscopy (SEM). The morphological characterization results are as follows: Figure 7As shown, the diaphragm 232 of this embodiment includes a base membrane 232a and a buffer layer 232b located on one side of the base membrane 232a. The buffer layer 232b includes a plurality of sheet-like particles 232c arranged in layers or side by side. There are gaps between the sheet-like particles 232c. An elastic adhesive 232d is distributed in the gaps between the sheet-like particles 232c.

[0070] In some embodiments, the thickness of the sheet-like particles 232c is 0.3 μm to 0.6 μm.

[0071] In the embodiments of this application, the thickness of the sheet-like particles 232c refers to the average geometric dimension along the direction perpendicular to its main surface, which can be observed using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The main surface of the sheet-like particles 232c refers to the largest planar area presented by the sheet-like particles 232c in space, which typically has two main surfaces opposite each other along the thickness direction. In addition to the main surfaces, other surfaces of the sheet-like particles 232c (such as the sides) are defined as secondary surfaces, whose areas are significantly smaller than the main surfaces. It is understood that the main surfaces are the primary interfaces for the sheet-like particles 232c to achieve stacking and relative sliding in the buffer layer 232b, while the secondary surfaces are only used for point contact or line contact between particles.

[0072] For example, the thickness of the sheet-like particles 232c can be 0.3μm, 0.35μm, 0.4μm, 0.45μm, 0.5μm, 0.55μm, 0.6μm, etc., or a range consisting of any two of the above values, such as 0.3μm~0.4μm, 0.4μm~0.5μm, 0.5μm~0.6μm, etc.

[0073] In the embodiments of this application, by limiting the thickness of the sheet particles 232c to the above-mentioned range, on the one hand, the sheet particles 232c have sufficient structural strength, reducing the breakage caused by insufficient strength and affecting the relative sliding between the sheet particles 232c; on the other hand, it can prevent the overall thickness of the buffer layer 232b from being too thick due to the excessive thickness of the sheet particles 232c, thereby reducing the adverse effects on the electrochemical performance of the battery cell 20.

[0074] In some embodiments, the volume average particle size Dv50 of the sheet-like particles 232c is 0.5 μm to 1 μm.

[0075] The volume average particle size (Dv50) refers to the median diameter based on the particle volume distribution. Specifically, it represents the diameter at which 50% of the particles are smaller than this value and 50% are larger than it, based on volume fraction. The volume average particle size (Dv50) of the flaky particles 232c can be measured using a laser particle size analyzer. The principle is to treat the flaky particles 232c as equivalent spheres of the same volume; the median diameter of this equivalent sphere is the volume average particle size (Dv50).

[0076] For example, the volume average particle size Dv50 of the sheet-like particles 232c can be 0.5μm, 0.5μm, 0.5μm, 0.5μm, 0.5μm, 0.5μm, 0.5μm, etc., or a range consisting of any two of the above values, such as 0.5μm~1μm, 0.5μm~1μm, 0.5μm~1μm, etc.

[0077] In the embodiments of this application, by limiting the volume average particle size Dv50 of the sheet particles 232c to the above-mentioned range, on the one hand, the sheet particles 232c have suitable planar dimensions and can form a flat geometric shape, thereby enabling orderly stacking in the buffer layer 232b, which facilitates the relative sliding of the sheet particles 232c under the action of external force; on the other hand, it can prevent the overall thickness of the buffer layer 232b from being too thick due to the excessive size of the sheet particles 232c, thereby reducing the adverse effects on the electrochemical performance of the battery cell 20.

[0078] In some embodiments, the flake particles 232c include one of boehmite, alumina, silicon oxide, magnesium oxide, titanium oxide, tin oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, and calcium carbonate.

[0079] The flake-like particles 232c of the above-mentioned materials can be obtained commercially or produced by mechanical grinding, such as using a high-energy ball mill with hard abrasive media (such as zirconia balls) to break up the blocky material and peel it off along specific crystal planes through long-term grinding, thus forming the flake-like particles 232c of such materials. They can also be produced by chemical synthesis methods (such as precipitation, hydrothermal, sol-gel, and template methods).

[0080] In the embodiments of this application, by limiting the material of the sheet-like particles 232c to the aforementioned highly stable inorganic non-metallic or ceramic materials, the sheet-like particles 232c can exist stably in the electrolyte, reducing the probability of degradation or side reactions. At the same time, such materials usually also have high strength characteristics, making the sheet-like particles 232c less prone to breakage under impact loads, and can effectively dissipate impact energy through relative sliding between particles, thereby further reducing the risk of short circuit when the battery cell 20 is subjected to external impact.

[0081] In some embodiments, the volume average particle size Dv50 of the elastic adhesive 232d is 0.05 μm to 0.2 μm.

[0082] For example, the volume average particle size Dv50 of the elastic adhesive 232d can be 0.05μm, 0.07μm, 0.09μm, 0.1μm, 0.12μm, 0.15μm, 0.2μm, etc., or a range of any two of the above values, such as 0.05μm~0.09μm, 0.09μm~0.12μm, 0.12μm~0.2μm, etc.

[0083] In the embodiments of this application, by limiting the volume average particle size Dv50 of the elastic adhesive 232d to the above-mentioned range, the elastic adhesive 232d can effectively fill the gaps between the sheet-like particles 232c, reducing the probability of uneven filling or blockage.

[0084] In some embodiments, the elastic modulus of the elastic adhesive 232d is 0.3 MPa to 300 MPa.

[0085] In the embodiments of this application, the elastic modulus is common knowledge in the art and has a commonly known meaning in the art, and can be measured by methods and instruments in the art. For example, the elastic modulus of the elastic adhesive 232d can be 0.3MPa, 1MPa, 3MPa, 30MPa, 50MPa, 100MPa, 300MPa, etc., or a range of any two of the above values, such as 0.3MPa~3MPa, 3MPa~50MPa, 50MPa~300MPa, etc.

[0086] In the embodiments of this application, by limiting the elastic modulus of the elastic adhesive 232d to the above-mentioned range, on the one hand, it can effectively support the sheet particles 232c, and on the other hand, it can make the elastic adhesive 232d have sufficient elastic deformation capability, so that some impact energy can be dissipated through tensile deformation, which is beneficial to reducing the risk of short circuit when the battery cell 20 is subjected to external force impact.

[0087] In some embodiments, the elastic adhesive 232d includes one of polyurethane, polyvinyl alcohol, chitosan, silk protein, polyacrylamide, polydimethylsiloxane, and sodium carboxymethyl cellulose.

[0088] In the embodiments of this application, by limiting the elastic adhesive 232d to the aforementioned material, on the one hand, the elastic adhesive 232d has a moderate adhesive strength, preventing the sliding between the sheet-like particles 232c from being hindered due to excessive adhesive force; on the other hand, the aforementioned material also has a suitable elastic modulus, so that the elastic adhesive 232d can dissipate some of the impact energy through tensile deformation, which is beneficial to reducing the risk of short circuit when the battery cell 20 is subjected to external impact.

[0089] In some embodiments, the mass percentage of the elastic adhesive 232d is 5% to 25% based on the total mass of the buffer layer 232b.

[0090] For example, the mass percentage of the elastic adhesive 232d can be 5%, 8%, 11%, 14%, 17%, 20%, 25%, etc., or a range of any two of the above values, such as 5% to 11%, 11% to 17%, 17% to 25%, etc.

[0091] In the embodiments of this application, by limiting the mass percentage of the elastic adhesive 232d within the above-mentioned range, the elastic adhesive 232d can be distributed in a discrete form within the gaps of the sheet particles 232c, forming a point contact network of "sheet particles 232c - elastic adhesive 232d - sheet particles 232c", reducing gap blockage caused by overfilling. This arrangement allows the sheet particles 232c to slide relatively freely, while maintaining the stability of the overall structure of the buffer layer 232b through the contact network.

[0092] In some embodiments, the sheet-like particles 232c have two opposing main surfaces, and the gap size between adjacent sheet-like particles 232c is 0.02 μm to 0.2 μm along the direction perpendicular to the main surfaces, and / or, the gap size between adjacent sheet-like particles 232c is 0.1 μm to 1 μm along the direction parallel to the main surfaces.

[0093] In the embodiments of this application, the gap size of adjacent sheet particles 232c along the direction perpendicular to the main surface refers to the minimum vertical distance between the planes where the main surfaces of two adjacent sheet particles 232c are located; the gap size of adjacent sheet particles 232c along the direction parallel to the main surface refers to the minimum straight-line distance between the edges of the two particle outlines after the outline of one sheet particle 232c is projected onto the plane where the main surface of the other sheet particle 232c is located.

[0094] For example, along the direction perpendicular to the main surface, the gap size between adjacent sheet-like particles 232c can be 0.02μm, 0.04μm, 0.08μm, 0.1μm, 0.12μm, 0.15μm, 0.2μm, etc., or a range consisting of any two of the above values, such as 0.02μm~0.08μm, 0.08μm~0.12μm, 0.12μm~0.2μm, etc.; along the direction parallel to the main surface, the gap size between adjacent sheet-like particles 232c can be 0.1μm, 0.2μm, 0.3μm, 0.5μm, 0.7μm, 0.9μm, 1μm, etc., or a range consisting of any two of the above values, such as 0.1μm~0.3μm, 0.3μm~0.7μm, 0.7μm~1μm, etc.

[0095] In the embodiments of this application, by limiting the gap size of adjacent sheet-like particles 232c in the direction perpendicular or parallel to the main surface to the aforementioned range, on the one hand, suitable sliding freedom can be provided for the sheet-like particles 232c, and on the other hand, the risk of structural collapse caused by excessive gaps can be reduced. It is understood that with gaps formed in the direction perpendicular or parallel to the main surface, when the battery cell 20 is subjected to external impact, the impact energy can be effectively dissipated through the sliding of the sheet-like particles 232c in the direction parallel or close to its main surface, and the impact energy can also be absorbed through the elastic deformation of the elastic adhesive 232d, thereby helping to reduce the risk of short circuits in the battery cell 20 when subjected to external impacts.

[0096] In some embodiments, the thickness of the buffer layer 232b is 1 μm to 6 μm.

[0097] For example, the thickness of the buffer layer 232b can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, etc., or a range of any two of the above values, such as 1μm~3μm, 3μm~4μm, 4μm~6μm, etc.

[0098] In the embodiments of this application, by limiting the thickness of the buffer layer 232b to the above-mentioned range, on the one hand, the battery cell 20 can effectively resist external impacts through the buffer layer 232b, reducing the risk of short circuit when the battery cell 20 is subjected to external impacts; on the other hand, it can also reduce the adverse effects on the electrochemical performance of the battery cell 20 caused by excessive thickness of the buffer layer 232b.

[0099] In some embodiments, please refer to Figure 8 , Figure 8 yes Figure 4The diagram shows the division of the first region 23b and the second region 23c of the electrode assembly 23. The diaphragm 232 includes a first diaphragm 2321 and a second diaphragm 2322. The electrode assembly 23 includes a first region 23b and a second region 23c. The second region 23c is disposed close to the housing 22 relative to the first region 23b. The first diaphragm 2321 is located in the first region 23b, and the second diaphragm 2322 is located in the second region 23c. The thickness of the first diaphragm 2321 is H1, and the thickness of the second diaphragm 2322 is H2, where H2 > H1.

[0100] In the embodiments of this application, the thicknesses of the first diaphragm 2321 and the second diaphragm 2322 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.

[0101] 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 23 region (i.e., the second region 23c). By providing a second separator 2322 with a larger thickness in the second region 23c, i.e., the second separator 2322 has higher mechanical strength and deformation volume, when the battery cell 20 is subjected to an external impact, the second separator 2322 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 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 2321 in the first region 23b, which has a lower impact risk, can retain higher ion transport efficiency and volumetric energy density, thereby helping to maintain good electrochemical performance of the battery cell 20.

[0102] In some embodiments, such as Figure 8 As shown, the diaphragm 232 includes a first diaphragm 2321 and a second diaphragm 2322, and the electrode assembly 23 includes a first region 23b and a second region 23c. The second region 23c is disposed close to the housing 22 relative to the first region 23b. The first diaphragm 2321 is located in the first region 23b, and the second diaphragm 2322 is located in the second region 23c. The adhesion force between the first diaphragm 2321 and the electrode 231 is F1, and the adhesion force between the second diaphragm 2322 and the electrode 231 is F2, where F1 > F2 and F2 ≤ 10 N / m.

[0103] 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.

[0104] In the embodiments of this application, by placing the second separator 2322 in the second region 23c near the housing 22 and adjusting its adhesive force to a specific range, when the battery cell 20 is subjected to an external impact, the low adhesive force between the second separator 2322 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 further reducing the probability of short circuit when the battery cell 20 is subjected to an external impact. In addition, by setting the first separator 2321 to have a higher adhesive force relative to the second separator 2322, 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 adhesive force of the separator 232.

[0105] In some embodiments, the diaphragm 232 further includes an adhesive coating, and a buffer layer 232b is disposed between the base membrane 232a and the adhesive coating.

[0106] In the embodiments of this application, by providing an adhesive coating, on the one hand, the interfacial adhesion between the diaphragm 232 and the electrode 231 can be enhanced, which is beneficial to improving the structural stability of the electrode assembly 23; on the other hand, the provision of the adhesive coating can further enhance the mechanical properties of the diaphragm 232, thereby reducing the risk of the diaphragm 232 being punctured.

[0107] 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, The device includes an electrode assembly and a housing. The electrode assembly is housed within the housing. The electrode assembly includes electrode sheets and a diaphragm disposed between the electrode sheets. The diaphragm includes a base film and a buffer layer disposed on at least one side of the base film. The buffer layer includes a plurality of spaced-apart sheet-like particles and an elastic adhesive filling the gaps between the sheet-like particles.

2. The battery cell according to claim 1, characterized in that, The thickness of the flaky particles is 0.3 μm to 0.6 μm.

3. The battery cell according to claim 1, characterized in that, The volume average particle size Dv50 of the flaky particles is 0.5 μm to 1 μm.

4. The battery cell according to claim 1, characterized in that, The flaky particles include one of the following: boehmite, alumina, silicon dioxide, magnesium oxide, titanium dioxide, tin oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, and calcium carbonate.

5. The battery cell according to claim 1, characterized in that, The volume average particle size Dv50 of the elastic adhesive is 0.05μm~0.2μm.

6. The battery cell according to claim 1, characterized in that, The elastic modulus of the elastic adhesive is 0.3 MPa to 300 MPa.

7. The battery cell according to claim 1, characterized in that, The elastic adhesive includes one of polyurethane, polyvinyl alcohol, chitosan, silk protein, polyacrylamide, polydimethylsiloxane, and sodium carboxymethyl cellulose.

8. The battery cell according to claim 1, characterized in that, Based on the total mass of the buffer layer, the mass percentage of the elastic adhesive is 5% to 25%.

9. The battery cell according to claim 1, characterized in that, The sheet-like particles have two opposing main surfaces. The gap size between adjacent sheet-like particles is 0.02 μm to 0.2 μm in a direction perpendicular to the main surfaces, and / or the gap size between adjacent sheet-like particles is 0.1 μm to 1 μm in a direction parallel to the main surfaces.

10. The battery cell according to claim 1, characterized in that, The thickness of the buffer layer is 1μm to 6μm.

11. The battery cell according to any one of claims 2 to 10, characterized in that, The diaphragm includes a first diaphragm and a second diaphragm. The electrode assembly includes a first region and a second region. The second region is 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 thickness of the first diaphragm is H1, and the thickness of the second diaphragm is H2, where H2 > H1.

12. The battery cell according to any one of claims 2 to 10, characterized in that, The diaphragm includes a first diaphragm and a second diaphragm. The electrode assembly includes a first region and a second region. The second region is 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 adhesion force between the first diaphragm and the electrode is F1, and the adhesion force between the second diaphragm and the electrode is F2, where F1 > F2 and F2 ≤ 10 N / m.

13. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1 to 12.

14. An electrical appliance, characterized in that, Includes the battery device as described in claim 13.

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