Battery cell, battery, and electrical device

Abstract

A battery cell, a battery, and an electrical device. The battery cell comprises an electrode assembly. The electrode assembly comprises a first electrode plate, a second electrode plate and a separator, polarities of the first electrode plate and the second electrode plate being opposite, and the separator being disposed between the first electrode plate and the second electrode plate. The separator comprises a substrate layer and a first functional layer, the substrate layer being provided with a first surface in the thickness direction thereof, and the first functional layer being disposed on the first surface. Thus the short-circuit risk of a battery cell can be reduced, and the reliability of the battery cell can be improved.

Description

Battery cells, batteries and electrical equipment CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Chinese patent application No. 202420577718.6, filed on March 25, 2024, entitled “Battery Cell, Battery and Electrical Equipment,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0003] With the development of new energy technologies, batteries are being used more and more widely. Batteries have high energy density, high reliability, long service life, and are environmentally friendly to the social environment. They have been widely used in passenger cars, commercial vehicles, electric bicycles, heavy trucks, energy storage facilities, battery swap stations, engineering manufacturing, smart devices, etc. At the same time, they also promote technological development and research in communication terminals, medical devices, energy development, etc.

[0004] In the process of battery technology development, how to improve the reliability of battery cells is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] The embodiments of the present application provide a battery cell, a battery, and an electrical device, which can effectively improve the reliability of the battery cell.

[0006] In a first aspect, an embodiment of the present application provides a battery cell, which includes an electrode assembly, wherein the electrode assembly includes a first pole piece, a second pole piece and a diaphragm, wherein the first pole piece and the second pole piece have opposite polarities, and the diaphragm is arranged between the first pole piece and the second pole piece; wherein the diaphragm includes a substrate layer and a first functional layer, wherein the substrate layer has a first surface in a thickness direction thereof, and the first functional layer is arranged on the first surface.

[0007] In the above technical solution, the diaphragm includes a substrate layer and a first functional layer. The first functional layer is arranged on the first surface of the substrate layer. The first functional layer can improve at least one of the heat resistance and puncture resistance of the diaphragm, improve the reliability of the diaphragm, reduce the risk of short circuit in the battery cell, and improve the reliability of the battery cell.

[0008] In some embodiments, the electrode assembly further includes a first electrode tab connected to one end of the first electrode sheet in a first direction; along the first direction, a size of the first functional layer is smaller than a size of the substrate layer.

[0009] In the above technical solution, the size of the first functional layer is smaller than that of the substrate layer. In this way, the occupation of the internal space of the battery cell by the first functional layer in the first direction can be reduced, and in the area where the first functional layer is not provided, the degree of mutual squeezing between the first electrode sheet, the diaphragm and the second electrode sheet is alleviated, and a small gap C can be formed at the position where the first functional layer is not provided. The gap can accommodate the electrolyte and improve the wettability. The gap is also conducive to the discharge of gases generated by side reactions inside the electrode assembly, thereby improving the reliability of the battery cell.

[0010] In some embodiments, along the first direction, the size of the first functional layer is H1, and the size of the substrate layer is H2, satisfying 1 / 30≤H1 / H2≤29 / 30.

[0011] In the above technical solution, 1 / 30≤H1 / H2≤29 / 30 can take into account the short circuit problem within the battery cell, the wettability problem of the electrolyte, and the exhaust problem of the electrode assembly, and can improve the reliability of the battery cell.

[0012] In some embodiments, the substrate layer has a first edge and a second edge arranged opposite to each other along the first direction, and the first tab and the first edge are located on the same side of the first direction; wherein, along the first direction, the first functional layer and the second edge are spaced apart.

[0013] In the above technical solution, the first functional layer is spaced apart from the second edge along the first direction, and the first functional layer is not provided at the position of the first substrate layer near the second edge, which can reduce the amount of the first functional layer. At the same time, a small gap can be formed between the area of ​​the first substrate layer near the second edge where the first functional layer is not provided and its corresponding electrode piece. The gap can both accommodate the electrolyte and facilitate the discharge of gas inside the electrode assembly from the gap, thereby improving the reliability of the battery cell.

[0014] In some embodiments, along the first direction, the first functional layer extends to the first edge.

[0015] In the above technical solution, the first functional layer extends to the first edge, which can enhance the heat resistance or puncture resistance of the diaphragm near the first edge, reduce the risk of diaphragm shrinkage due to the temperature rise of the first pole ear or the first pole ear puncturing the diaphragm, reduce the risk of short circuit in the battery cell, and improve the reliability of the battery cell.

[0016] In some embodiments, the electrode assembly further includes a second electrode tab connected to one end of the second electrode sheet in the first direction, and the first electrode tab and the second electrode tab are located on the same side in the first direction.

[0017] In the above technical solution, the first pole ear and the second pole ear are arranged on the same side in the first direction, and the first pole ear and the second pole ear affect the same side of the diaphragm. The first functional layer can alleviate the influence of the first pole ear on the diaphragm, and alleviate the influence of the second pole ear on the diaphragm. There is no need to set an additional first functional layer for the second pole ear, which reduces the demand for the first functional layer and can improve the energy density of the battery cell.

[0018] In some embodiments, along the first direction, the first functional layer is spaced apart from the first edge.

[0019] In the above technical solution, the first functional layer is arranged at intervals from the first edge, which can further reduce the amount of the first functional layer used. At the same time, a tiny gap can be formed between the area of ​​the first substrate layer near the first edge where the first functional layer is not set and its corresponding electrode piece. The gap can not only accommodate the electrolyte, but also facilitate the discharge of gas inside the electrode assembly from the gap, thereby further improving the reliability of the battery cell.

[0020] In some embodiments, the electrode assembly further includes a second electrode tab, which is connected to one end of the second electrode sheet in the first direction, and the first electrode tab and the second electrode tab are located on opposite sides of the first direction; the substrate layer has a first edge and a second edge oppositely arranged along the first direction; wherein, the first functional layer includes a first part and a second part, the first part and the second part are spaced apart along the first direction, and along the first direction, the first part extends to the first edge, and the second part extends to the second edge.

[0021] In the above technical solution, the first and second portions are spaced apart along the first direction, and the first functional layer is not provided in the spaced apart locations, thereby reducing the amount of the first functional layer used. Furthermore, the gap formed between the substrate layer and the corresponding electrode sheet is located near the center, which increases the electrolyte storage capacity in the center and improves the venting effect in the center of the electrode assembly, thereby enhancing the reliability of the battery cell.

[0022] In some embodiments, the electrode assembly further includes a first electrode tab connected to one end of the first electrode sheet in a first direction; a plurality of first functional layers are provided, and the plurality of first functional layers are arranged at intervals along a second direction, and the second direction is perpendicular to the first direction.

[0023] In the above technical solution, the first functional layers are arranged at intervals along the second direction. No first functional layers are provided at the intervals along the second direction, further reducing the amount of first functional layers used. Furthermore, multiple gaps are formed at the intervals between the first functional layers, further increasing electrolyte storage capacity and enhancing the venting effect of the electrode assembly, thereby improving the reliability of the battery cells.

[0024] In some embodiments, the electrode assembly is a wound structure, and the second direction is the winding direction of the electrode assembly.

[0025] In some embodiments, the electrode assembly is flat and includes a straight region and a bent region, and at least a portion of the first functional layer is located in the straight region.

[0026] In the above technical solution, at least a portion of the first functional layer is located in the flat area, which can alleviate the heat resistance of the diaphragm in the flat area, reduce the risk of shrinkage or melting in the flat area, and alleviate the risk of short circuit in the battery cell, thereby improving the reliability of the battery cell.

[0027] In some embodiments, the electrode assembly is flat and includes a straight region and a bent region, and at least a portion of the first functional layer is located in the bent region.

[0028] In the above technical solution, at least a portion of the first functional layer is located in the bending area, which can reduce the risk of puncture of the diaphragm in the bending area, reduce the risk of short circuit in the battery cell, and improve the reliability of the battery cell.

[0029] In some embodiments, the material of the first functional layer includes one of aluminum oxide, silicon dioxide, boehmite, and titanium dioxide.

[0030] In some embodiments, the substrate layer has a second surface opposite to the first surface in a thickness direction thereof, and the diaphragm further includes a second functional layer disposed on the second surface.

[0031] In the above technical solution, the second functional layer can further improve the local heat resistance or puncture resistance of the diaphragm, alleviate the short circuit in the battery cell, and improve the reliability of the battery cell.

[0032] In a second aspect, an embodiment of the present application provides a battery, which includes a battery cell provided by any embodiment of the first aspect.

[0033] In a third aspect, an embodiment of the present application provides an electrical device, which includes a battery cell provided by any embodiment of the first aspect or a battery provided by an embodiment of the second aspect, and the battery cell or the battery is used to power the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0035] FIG1 is a schematic structural diagram of a vehicle according to some embodiments of the present application;

[0036] FIG2 is an exploded schematic diagram of a battery according to some embodiments of the present application;

[0037] FIG3 is an exploded schematic diagram of a battery cell according to some embodiments of the present application;

[0038] FIG4 is a schematic structural diagram of an electrode assembly according to some embodiments of the present application;

[0039] FIG5 is a schematic structural diagram of electrode assemblies according to other embodiments of the present application;

[0040] FIG6 is a schematic structural diagram of a diaphragm according to some embodiments of the present application;

[0041] FIG7 is a schematic structural diagram of diaphragms in other embodiments of the present application;

[0042] FIG8 is a schematic structural diagram of electrode assemblies according to some other embodiments of the present application;

[0043] FIG9 is a schematic structural diagram of diaphragms in some other embodiments of the present application;

[0044] FIG10 is a schematic structural diagram of an electrode assembly according to some further embodiments of the present application;

[0045] FIG11 is a schematic diagram of the structure of a diaphragm in a wound electrode assembly according to some embodiments of the present application;

[0046] FIG12 is a schematic diagram of the structure of a diaphragm in a wound electrode assembly in other embodiments of the present application;

[0047] FIG13 is a schematic structural diagram of electrode assemblies according to some other embodiments of the present application.

[0048] Icon: 1000-Vehicle; 100-Battery; 200-Motor; 300-Controller;

[0049] 10-battery cell; 11-end cover; 12-housing;

[0050] 20-box; 21-first sub-box; 22-second sub-box; 23-accommodation space;

[0051] 30-electrode assembly;

[0052] 31-first pole piece; 31a-positive pole piece; 311-first pole tab;

[0053] 32-second electrode; 32a-negative electrode; 321-second electrode tab;

[0054] 33-diaphragm; 331-substrate layer; 3311-first surface; 3312-second surface; 3313-first edge; 3314-second edge; 332-first functional layer; 3321-first portion; 3322-second portion; 333-second functional layer;

[0055] A-straight area; B-first bending area; C-second bending area;

[0056] Z-first direction; X-thickness direction; Y-second direction; R-winding direction.

[0057] The drawings are not drawn to scale. DETAILED DESCRIPTION

[0058] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0059] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0060] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0061] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0062] In the description of this application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly perpendicular, but is within the allowable error range. "Parallel" is not strictly parallel, but is within the allowable error range.

[0063] The term "or" in this application is merely a description of the association relationship between associated objects, indicating that two relationships may exist. For example, A or B can represent two situations: A exists alone, and B exists alone.

[0064] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0065] The term "plurality" used in this application refers to two or more (including two).

[0066] In this application, battery cells may include, but are not limited to, lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries. Battery cells include, but are not limited to, cylindrical, flat, rectangular, or other shapes. Battery cells are generally packaged in cylindrical, prismatic, and soft-pack shapes.

[0067] A battery cell consists of an electrode assembly and an electrolyte. The electrode assembly is composed of a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrodes. Metal ions (such as lithium ions) are inserted and removed from the positive and negative electrodes. The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0068] The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode collector. The positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer. The positive electrode collector not coated with the positive electrode active material layer serves as the positive electrode tab.

[0069] Taking lithium-ion batteries as an example, the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. The positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, carbon electrode, carbon, nickel or titanium, etc. can be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0070] The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode collector. The negative electrode collector not coated with the negative electrode active material layer protrudes from the negative electrode collector coated with the negative electrode active material layer. The negative electrode collector not coated with the negative electrode active material layer serves as the negative electrode tab.

[0071] The negative electrode current collector can be a metal foil or a composite current collector. For example, the metal foil can be silver-plated aluminum, silver-plated stainless steel, stainless steel, copper, aluminum, carbon, carbon, nickel, or titanium. The negative electrode active material can be carbon or silicon, for example.

[0072] To reduce the risk of the tabs fusing when high current flows through them, multiple positive tabs are stacked together, and multiple negative tabs are stacked together. Furthermore, the electrode assembly can be either a wound or laminated structure.

[0073] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing for enclosing one or more battery cells. The casing can reduce the effects of liquids or other foreign matter on the charging or discharging of the battery cells.

[0074] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0075] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0076] In some embodiments, multiple battery cells can be first integrated into at least one battery module, which is then installed in a housing to form a battery pack. In this embodiment, auxiliary structural members such as crossbeams can be installed between the battery modules to improve the stability of the battery module installation in the housing.

[0077] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0078] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0079] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery reliability must also be considered.

[0080] For typical battery cells, a diaphragm is placed between the positive and negative electrodes to insulate them. The diaphragm significantly impacts the reliability of the battery cell. Low diaphragm reliability leads to insulation failure, and the battery cell is susceptible to internal short circuits. For example, the edges of the diaphragm shrink due to heat, causing the edges of the positive and negative electrodes to contact and short-circuit; localized high temperatures can cause the diaphragm to partially melt, causing the positive and negative electrodes to contact and short-circuit at the location where the diaphragm melts; or the diaphragm is punctured by other components, causing the positive and negative electrodes to contact and short-circuit at the location where the diaphragm is punctured.

[0081] In view of this, in order to solve the problem of diaphragm reliability leading to short circuit in battery cells, the embodiment of the present application provides a technical solution. By setting a functional layer locally on the diaphragm, the functional layer can improve the insulation reliability of the diaphragm, reduce the risk of short circuit in the battery cell, and thus improve the reliability of the battery cell.

[0082] Among them, the functional layer is a component that improves the reliability of the diaphragm and alleviates the short circuit between the positive and negative electrodes.

[0083] The technical solutions disclosed in the embodiments of the present application are applicable to, but not limited to, batteries and electrical equipment using batteries.

[0084] Electrically powered equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools. Vehicles can be fuel-powered, gas-powered, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles, or extended-range vehicles. Spacecraft include aircraft, rockets, space shuttles, and spacecraft. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers.

[0085] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle 1000 as an example.

[0086] Please refer to FIG1 , which is a schematic diagram of the structure of a vehicle 1000 according to some embodiments of the present application. A battery 100 is disposed inside the vehicle 1000 . The battery 100 can be disposed at the bottom, head, or tail of the vehicle 1000 . The battery 100 can be used to power the vehicle 1000 . For example, the battery 100 can serve as an operating power source for the vehicle 1000 .

[0087] The vehicle 1000 may further include a controller 300 and a motor 200 . The controller 300 is used to control the battery 100 to supply power to the motor 200 , for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0088] In some embodiments of the present application, the battery 100 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0089] In some embodiments, please refer to FIG. 2 , which is an exploded schematic diagram of a battery 100 according to some embodiments of the present application. The battery 100 includes a plurality of battery cells 10. The plurality of battery cells 10 may be connected in series, in parallel, or in a hybrid connection. The term "hybrid connection" refers to the connection of the plurality of battery cells 10 in both series and parallel.

[0090] In some embodiments, the battery 100 may further include a busbar component (not shown), and the multiple battery cells 10 may be electrically connected via the busbar component to achieve series connection, parallel connection, or mixed connection of the multiple battery cells 10 .

[0091] The busbar component may be a metal conductor, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0092] In some embodiments, the battery 100 may further include a housing 20 for accommodating the battery cells 10. The housing 20 may include a first sub-housing 21 and a second sub-housing 22, which cover each other to define a storage space 23 for accommodating the battery cells 10. The connection between the first sub-housing 21 and the second sub-housing 22 may be sealed by a sealing element (not shown), such as a sealing ring or sealant.

[0093] The first sub-box 21 and the second sub-box 22 can have various shapes, such as a rectangular parallelepiped, a cylinder, etc. The first sub-box 21 can be a hollow structure with one side open, and the second sub-box 22 can also be a hollow structure with one side open. The open side of the second sub-box 22 covers the open side of the first sub-box 21, thereby forming the box 20 with the storage space 23. Of course, the first sub-box 21 can also be a hollow structure with one side open, and the second sub-box 22 can be a plate-like structure. The second sub-box 22 covers the open side of the first sub-box 21, thereby forming the box 20 with the storage space 23.

[0094] Please refer to FIG. 3 , which is an exploded schematic diagram of a battery cell 10 according to some embodiments of the present application. The battery cell 10 may include a housing 12 , an electrode assembly 30 , an end cap 11 and other functional components.

[0095] The housing 12 is a component for accommodating the electrode assembly 30. The housing 12 can be a hollow structure with an opening at one end, or a hollow structure with openings at both ends. The housing 12 can be made of a variety of materials, such as copper, iron, aluminum, steel, and aluminum alloys. The housing 12 can have a variety of shapes, such as a cylinder or a rectangular parallelepiped. For example, in FIG3 , the housing 12 is a rectangular parallelepiped.

[0096] The end cap 11 is a component that covers the opening of the shell 12 to isolate the internal environment of the battery cell 10 from the external environment. The end cap 11 covers the opening of the shell 12, and the end cap 11 and the shell 12 together define a sealed space for accommodating the electrode assembly 30, electrolyte and other functional components. The shape of the end cap 11 can be adapted to the shape of the shell 12. For example, the shell 12 is a rectangular parallelepiped structure, and the end cap 11 is a rectangular plate structure adapted to the shell 12. For another example, the shell 12 is a cylindrical structure, and the end cap 11 is a circular plate structure adapted to the shell 12. The material of the end cap 11 can also be various. For example, the end cap 11 can be made of metal, such as copper, iron, aluminum, steel, aluminum alloy, etc. The material of the end cap 11 can be the same as or different from the material of the shell 12.

[0097] In the battery cell 10, there can be one or two end caps 11. If the housing 12 is a hollow structure with an opening at one end, one end cap 11 is provided accordingly; if the housing 12 is a hollow structure with openings at both ends, two end caps 11 are provided accordingly, with the two end caps 11 covering the two openings of the housing 12 respectively.

[0098] The electrode assembly 30 is a component where chemical reactions occur. In the battery cell 10, there can be one or more electrode assemblies 30. The number of electrode assemblies 30 is set according to specific energy requirements. For example, in FIG3 , there are two electrode assemblies 30.

[0099] FIG4 is a schematic diagram of the structure of the electrode assembly 30 according to some embodiments of the present application; FIG5 is a schematic diagram of the structure of the electrode assembly 30 according to other embodiments of the present application.

[0100] 4 and 5 , an embodiment of the present application provides a battery cell 10, which includes an electrode assembly 30. The electrode assembly 30 includes a first electrode sheet 31, a second electrode sheet 32, and a diaphragm 33. The first electrode sheet 31 and the second electrode sheet 32 ​​have opposite polarities, and the diaphragm 33 is arranged between the first electrode sheet 31 and the second electrode sheet 32. The diaphragm 33 includes a substrate layer 331 and a first functional layer 332. The substrate layer 331 has a first surface 3311 in its thickness direction X, and the first functional layer 332 is arranged on the first surface 3311.

[0101] The first electrode 31 can be a positive electrode 31a, or a negative electrode 32a. If the first electrode 31 is a positive electrode 31a, the second electrode 32 is a negative electrode 32a. If the first electrode 31 is a negative electrode 32a, the second electrode 32 is a positive electrode 31a. Alternatively, the first electrode 31 is a positive electrode 31a, and the second electrode 32 is a negative electrode 32a.

[0102] The electrode assembly 30 may be a laminated structure or a wound structure. For example, in FIG3 , the electrode assembly 30 is a wound structure.

[0103] The diaphragm 33 includes a substrate layer 331 and a first functional layer 332. The substrate layer 331 is the main body of the diaphragm 33. The material of the substrate layer includes but is not limited to PP (polypropylene) or PE (polyethylene).

[0104] The substrate layer 331 has a first surface 3311 in its thickness direction X. The first surface 3311 may be the surface of the substrate layer 331 facing the first electrode sheet 31, or the first surface 3311 may be the surface of the substrate layer 331 facing the second electrode sheet 32. For example, as shown in Figures 4 and 5, the surface of the substrate layer 331 facing the positive electrode sheet 31a is the first surface 3311, and the surface of the substrate layer 331 facing the negative electrode sheet 32a is the second surface 3312.

[0105] The first functional layer 332 is arranged on the first surface 3311, and the substrate layer 331 is the arrangement basis of the first functional layer 332. Specifically, the substrate layer 331 includes a substrate and a film layer. The film layer coats the entire surface of the substrate. The surface of the film layer facing away from the substrate is the first surface 3311. The first functional layer 332 is arranged on the surface of the film layer facing away from the substrate.

[0106] The first functional layer 332 is a material layer used to enhance the performance of the diaphragm 33 to alleviate short circuits within the battery cell 10. The first functional layer 332 can be used to enhance the heat resistance of the diaphragm 33, alleviate the melting or shrinkage of the diaphragm 33, and thus heat the short circuit within the battery cell 10. The first functional layer 332 can be used to enhance the puncture resistance of the diaphragm 33, alleviate the diaphragm 33 from being punctured by lithium dendrites, and thus heat the short circuit within the battery cell 10. Of course, the first functional layer 332 can simultaneously enhance the heat resistance, shrinkage resistance, and puncture resistance of the diaphragm. The first functional layer 332 can be a coating structure coated on the first surface 3311.

[0107] To improve the performance of the diaphragm, the first functional layer 332 may be made of an inorganic ceramic material. This inorganic ceramic material can simultaneously enhance the heat resistance, shrinkage resistance, and puncture resistance of the area where the first functional layer 332 is disposed. The material of the first functional layer 332 includes, but is not limited to, alumina, silica, boehmite, titanium dioxide, and the like.

[0108] Typically, the diaphragm is made of PE or PP materials, which have poor heat resistance. When heated, the diaphragm shrinks or even melts, causing a short circuit within the battery cell. Alternatively, the diaphragm has poor puncture resistance and is easily punctured, causing a short circuit within the battery cell.

[0109] In this embodiment, the diaphragm 33 includes a substrate layer 331 and a first functional layer 332. The first functional layer 332 is arranged on the first surface 3311 of the substrate layer 331. The first functional layer 332 can improve at least one of the heat resistance and puncture resistance of the diaphragm 33, improve the reliability of the diaphragm 33, reduce the risk of short circuit in the battery cell 10, and improve the reliability of the battery cell 10.

[0110] 4 and 5 , in some embodiments, the electrode assembly 30 further includes a first electrode tab 311 , which is connected to one end of the first electrode sheet 31 in the first direction Z. Along the first direction Z, a size H1 of the first functional layer 332 is smaller than a size H2 of the substrate layer 331 .

[0111] It is understandable that the first functional layer 332 does not continuously cover the entire first surface 3311 along the first direction Z. The first functional layer 332 can be disposed at an upper portion of the substrate layer 331 in the first direction Z (as shown in FIG4 ), or at a middle portion in the first direction Z (as shown in FIG5 ), or at a lower portion in the first direction Z.

[0112] It should be noted that the size H1 of the first functional layer 332 is smaller than the size H2 of the base layer 331 .

[0113] Along the first direction Z, the size H1 of the first functional layer 332 is smaller than the size H2 of the substrate layer 331. In this way, the occupation of the internal space of the battery cell 10 by the first functional layer 332 in the first direction Z can be reduced, and in the area where the first functional layer 332 is not provided, the degree of mutual squeezing between the first electrode sheet 31, the diaphragm 33 and the second electrode sheet 32 ​​is alleviated, and a small gap C can be formed at the position where the first functional layer 332 is not provided. The gap can accommodate the electrolyte and improve the wettability. The gap is also conducive to the discharge of gases generated by side reactions inside the electrode assembly 30, thereby improving the reliability of the battery cell 10.

[0114] For example, in FIG. 4 , the first functional layer 332 is disposed on the upper portion of the substrate layer 331 , and a gap C is formed between the lower portion of the substrate layer 331 where the first functional layer 332 is not disposed and the first pole piece 31 .

[0115] For example, in FIG5 , the first functional layer 332 is arranged in the middle of the substrate layer 331 , and a gap C is formed between the upper area of ​​the substrate layer 331 where the first functional layer 332 is not arranged and the first pole piece 31 , and a gap C is formed between the lower area of ​​the substrate layer 331 where the first functional layer 332 is not arranged and the first pole piece 31 .

[0116] As another example, in Figure 8, along the first direction Z, the first functional layer 332 is provided on the upper and lower parts of the substrate layer 331, and the first functional layer 332 is not provided in the middle part of the substrate layer 331. At this time, a gap C is formed between the area in the middle part of the substrate layer 331 where the first functional layer 332 is not provided and the first pole piece 31.

[0117] In some embodiments, along the first direction Z, the size of the first functional layer 332 is H1, and the size of the substrate layer 331 is H2, satisfying 1 / 30≤H1 / H2≤29 / 30.

[0118] Illustratively, H1 / H2 may be 1 / 30, 3 / 30, 530, 7 / 30, 11 / 30, 15 / 30, 16 / 30, 19 / 30, 20 / 30, 25 / 30, 29 / 30, and any value therebetween.

[0119] When 1 / 30 ≤ H1 / H2, the dimension of the first functional layer 332 in the first direction Z is not too small, which can improve the performance of the separator 33, thereby alleviating short circuits within the battery cell 10 and improving the reliability of the battery cell 10. When H1 / H2 ≤ 29 / 30, the first functional layer 332 does not continuously cover the entire first surface 3311 in the first direction Z. In areas where the first functional layer 332 is not provided, the degree of compression between the first electrode sheet 31, the separator 33, and the second electrode sheet 32 ​​is alleviated, which helps improve electrolyte wettability and enhances the venting effect within the electrode assembly 30, thereby improving the reliability of the battery cell 10. Therefore, when 1 / 30 ≤ H1 / H2 ≤ 29 / 30, the short circuit problem within the battery cell 10, the electrolyte wettability problem, and the venting problem within the electrode assembly 30 are all taken into account, thereby improving the reliability of the battery cell 10.

[0120] While the first functional layer 332 alleviates the short circuit in the battery cell 10, in order to reduce the usage of the first functional layer 332, it is necessary to set the first functional layer 332 as much as possible in the area of ​​the diaphragm 33 that is easily shrunken or punctured by heat, while the first functional layer 332 may not be set in other positions to achieve local performance enhancement of the diaphragm 33.

[0121] Figure 6 is a schematic diagram of the structure of the separator 33 in some embodiments of the present application; Figure 7 is a schematic diagram of the structure of the separator 33 in other embodiments of the present application. It should be noted that if the electrode assembly 30 has a laminated structure, Figures 6 and 7 illustrate a single separator 33 unit in the electrode assembly 30; if the electrode assembly 30 has a wound structure, Figures 6 and 7 illustrate the separator 33 in an unfolded state.

[0122] 6 and 7 , and in combination with FIG. 3 and 4 , in some embodiments, the substrate layer 331 has a first edge 3313 and a second edge 3314 arranged opposite to each other along the first direction Z, and the first electrode tab 311 and the first edge 3313 are located on the same side in the first direction Z; wherein, along the first direction Z, the first functional layer 332 and the second edge 3314 are arranged at intervals.

[0123] The first electrode tab 311 and the first edge 3313 are located on the same side in the first direction Z, which means that the first electrode tab 311 is disposed at an end of the first electrode sheet 31 close to the first edge 3313 .

[0124] The first functional layer 332 is spaced apart from the second edge 3314 , which means that the first functional layer 332 does not extend to the second edge 3314 .

[0125] Along the first direction Z, the first functional layer 332 is spaced apart from the second edge 3314, and the first functional layer 332 is not provided at the position of the first substrate layer 331 near the second edge 3314, which can reduce the usage of the first functional layer 332. At the same time, a small gap can be formed between the area of ​​the first substrate layer 331 near the second edge 3314 where the first functional layer 332 is not provided and the corresponding electrode sheet. The gap can accommodate the electrolyte and facilitate the discharge of gas inside the electrode assembly 30 from the gap, thereby improving the reliability of the battery cell 10.

[0126] 6 , in some embodiments, along the first direction Z, the first functional layer 332 extends to a first edge 3313 .

[0127] The first functional layer 332 extends to the first edge 3313, and may be aligned with the first edge 3313. As shown in FIG6 , along the first direction Z, the first functional layer 332 extends to the first edge 3313 and is spaced apart from the second edge 3314.

[0128] Because the first edge 3313 and the first tab 311 are on the same side of the electrode assembly 30, the portion of the diaphragm 33 near the first edge 3313 is relatively close to the first tab 311. When the battery cell 10 cycles, the overcurrent temperature of the first tab 311 increases. If the diaphragm 33 lacks heat resistance, the diaphragm 33 near the first edge 3313 may contract, causing the first pole piece 31 and the second pole piece 32 to contact, resulting in a short circuit within the battery cell 10. Furthermore, if the first tab 311 is wrinkled or has an uneven end surface, the first tab 311 may puncture the diaphragm 33 near the first edge 3313. Contact between the first pole piece 31 and the second pole piece 32 may cause a short circuit within the battery cell 10.

[0129] The first functional layer 332 extending to the first edge 3313 can enhance the heat resistance or puncture resistance of the diaphragm 33 near the first edge 3313, reduce the risk of the diaphragm 33 shrinking due to the heating of the first pole ear 311 or the first pole ear 311 puncturing the diaphragm 33, reduce the risk of short circuit in the battery cell 10, and improve the reliability of the battery cell 10.

[0130] When the first functional layer 332 extends to the first edge 3313 along the first direction Z and the first functional layer 332 is spaced apart from the second edge 3314, referring to Figure 4, in some embodiments, the electrode assembly 30 further includes a second pole ear 321, the second pole ear 321 is connected to one end of the second pole piece 32 in the first direction Z, and the first pole ear 311 and the second pole ear 321 are located on the same side in the first direction Z.

[0131] It can be understood that, in this embodiment, the first electrode tab 311 and the second electrode tab 321 are arranged on the same side in the first direction Z.

[0132] The first pole tab 311 and the second pole tab 321 are arranged on the same side in the first direction Z. The first pole tab 311 and the second pole tab 321 affect the same side of the diaphragm 33. The first functional layer 332 can alleviate the influence of the first pole tab 311 on the diaphragm 33, and can alleviate the influence of the second pole tab 321 on the diaphragm 33. There is no need to additionally set the first functional layer 332 for the second pole tab 321, which reduces the demand for the first functional layer 332 and can improve the energy density of the battery cell 10.

[0133] When the first functional layer 332 and the second edge 3314 are spaced apart along the first direction Z, referring to FIG. 5 and FIG. 7 , in some embodiments, the first functional layer 332 and the first edge 3313 are spaced apart along the first direction Z.

[0134] It is understood that in this embodiment, the first functional layer 332 does not extend to the first edge 3313 or the second edge 3314. The first functional layer 332 is not provided near the first edge 3313 of the first substrate layer 331, nor is the first functional layer 332 provided near the second edge 3314 of the first substrate layer 331.

[0135] The first functional layer 332 is spaced apart from the first edge 3313, which can further reduce the usage of the first functional layer 332. At the same time, a tiny gap can be formed between the area of ​​the first substrate layer 331 near the first edge 3313 where the first functional layer 332 is not provided and its corresponding electrode piece. The gap can accommodate the electrolyte and facilitate the discharge of gas inside the electrode assembly 30 from the gap, thereby further improving the reliability of the battery cell 10.

[0136] Typically, along the first direction Z, the heat dissipation effect near the middle of the electrode assembly 30 is weaker than the heat dissipation effect at the ends of the electrode assembly 30. Excessively high temperatures in the middle of the electrode assembly 30 may cause the electrode assembly 30 to shrink or even melt, thereby causing contact between the first electrode sheet 31 and the second electrode sheet 32 ​​and causing a short circuit within the battery cell 10. Therefore, in some embodiments, the first functional layer 332 is disposed near the middle of the substrate layer 331 in the first direction Z.

[0137] 5 , in some embodiments, the electrode assembly 30 further includes a second electrode tab 321 , which is connected to one end of the second electrode sheet 32 ​​in the first direction Z. The first electrode tab 311 and the second electrode tab 321 are located on opposite sides in the first direction Z.

[0138] FIG8 is a schematic structural diagram of an electrode assembly 30 according to some other embodiments of the present application; FIG9 is a schematic structural diagram of a diaphragm 33 according to some other embodiments of the present application.

[0139] 8 and 9 , in some embodiments, the substrate layer 331 has a first edge 3313 and a second edge 3314 arranged opposite to each other along the first direction Z; wherein the first functional layer 332 includes a first portion 3321 and a second portion 3322, and the first portion 3321 and the second portion 3322 are arranged at intervals along the first direction Z. Along the first direction Z, the first portion 3321 extends to the first edge 3313, and the second portion 3322 extends to the second edge 3314.

[0140] It can be understood that, in this embodiment, the first electrode tab 311 and the second electrode tab 321 are electrode tabs on opposite sides.

[0141] The first portion 3321 and the second portion 3322 are spaced apart along the first direction Z, which means that the first portion 3321 and the second portion 3322 are not continuously arranged. The distance between the first portion 3321 and the second portion 3322 along the first direction Z can be set according to the size and chemical system of the battery cell 10.

[0142] The first portion 3321 may extend to be flush with the first edge 3313 , and the second portion 3322 may extend to be flush with the second edge 3314 .

[0143] In this embodiment, the first portion 3321 and the second portion 3322 are spaced apart along the first direction Z. The first functional layer 332 is not provided in the spaced apart portions, thereby reducing the amount of the first functional layer 332. Furthermore, the gap C formed between the substrate layer 331 and the corresponding electrode sheet is located near the center, which increases the electrolyte storage capacity in the center and improves the venting effect in the center of the electrode assembly 30, thereby enhancing the reliability of the battery cell 10.

[0144] 6 , 7 , and 9 , in some embodiments, the electrode assembly 30 further includes a first electrode tab 311 , which is connected to one end of the first electrode piece 31 in the first direction Z; a plurality of first functional layers 332 are provided, and the plurality of first functional layers 332 are arranged at intervals along the second direction Y, and the second direction Y is perpendicular to the first direction Z.

[0145] If the electrode assembly 30 is a laminated structure, the second direction Y can be the length direction of the separator 33 or the width direction of the separator 33. Optionally, the first direction Z is the width direction of the separator 33, and the second direction Y is the length direction of the separator 33.

[0146] If the electrode assembly 30 is a wound structure, the second direction Y is the winding direction R of the separator 33 .

[0147] Multiple first functional layers 332 are arranged at intervals along the second direction Y. The interval distance between the multiple first functional layers 332 can gradually increase, or the interval distance between the multiple first functional layers 332 can gradually decrease. The multiple first functional layers 332 can also be arranged at equal intervals to facilitate controlling the position of the first functional layer 332.

[0148] The first functional layers 332 are arranged at intervals along the second direction Y. No first functional layer 332 is provided at the intervals along the second direction Y, further reducing the amount of first functional layer 332 used. Furthermore, multiple gaps can be formed at the intervals between the first functional layers 332, further increasing the electrolyte storage capacity and improving the venting effect of the electrode assembly 30, thereby enhancing the reliability of the battery cell 10.

[0149] FIG10 is a schematic structural diagram of an electrode assembly 30 according to some further embodiments of the present application.

[0150] 10 , in some embodiments, the electrode assembly 30 is a wound structure, and the second direction Y is the winding direction R of the electrode assembly 30 .

[0151] FIG11 is a schematic structural diagram of the separator 33 in the wound electrode assembly 30 according to some embodiments of the present application.

[0152] 10 and 11 , in some embodiments, the electrode assembly 30 is flat and includes a straight region A and a bent region. At least a portion of the first functional layer 332 is located in the straight region A.

[0153] The electrode assembly 30 may be formed by winding the electrode assembly 30 into a cylindrical shape and then flattening it.

[0154] The straight region A is the region where the straight sections of the first pole piece 31, the second pole piece 32 and the diaphragm 33 are located. The bent straight region A is the region where the bent sections of the first pole piece 31, the second pole piece 32 and the diaphragm 33 are located.

[0155] For example, in FIG10 , two bending regions are provided, namely a first bending region B and a second bending region C, which are respectively provided at both ends of the straight region A. Taking the separator 33 as an example, along the winding direction R of the electrode assembly 30, the straight sections and the bent sections of the separator 33 are arranged alternately, and two adjacent straight sections of the separator 33 are connected by a bent section.

[0156] At least a portion of the first functional layer 332 is located in the straight region A. This means that a portion of the first functional layer 332 is located in the straight region A. It is understood that the first functional layer 332 may not extend beyond the straight region A, or may extend beyond the straight region A and into the bend region. For example, in FIG11 , the first functional layer 332 is disposed in the straight region A, and is not disposed in the bend region.

[0157] In a battery cell 10, the straight region A corresponds to the large surface of the housing 12 of the battery cell 10, while the curved region corresponds to the narrow surface of the housing 12. Compared to the curved region, the straight region A provides closer contact with the housing. During a thermal diffusion test, the large surface is heated to a higher temperature, and the separator 33 in the straight region A is severely heated. This region can easily shrink or even melt, causing a short circuit within the battery 100.

[0158] At least a portion of the first functional layer 332 is located in the flat area A, which can alleviate the heat resistance of the diaphragm 33 in the flat area A, reduce the risk of shrinkage or melting in the flat area A, and alleviate the risk of short circuit in the battery cell 10, thereby improving the reliability of the battery cell 10.

[0159] Referring to Figure 11 , stress exists at the connection point D between the bent region and the flat region, making the separator 33 susceptible to damage there. Therefore, the first functional layer 332 can be positioned close to position D. Therefore, in some embodiments, the first functional layer 332 can extend beyond the connection point D along the winding direction R of the electrode assembly 30, with the excess dimension not exceeding 20 mm. In other embodiments, the first functional layer 332 can also extend within the connection point D along the winding direction R of the electrode assembly 30, with the distance from the first functional layer 332 to the connection point D not exceeding 20 mm.

[0160] FIG12 is a schematic structural diagram of the separator 33 in the wound electrode assembly 30 according to some other embodiments of the present application.

[0161] 12 and 10 , in some embodiments, the electrode assembly 30 is flat, and includes a straight region A and a bending region, and at least a portion of the first functional layer 332 is located in the bending region.

[0162] At least a portion of the first functional layer 332 is located in the bend region, meaning that a portion of the first functional layer 332 is located in the bend region. It is understood that the first functional layer 332 may not extend beyond the bend region, or may extend beyond the bend region and into the straight region A. For example, in FIG11 , the first functional layer 332 is disposed in the bend region, and the first functional layer 332 is not disposed in the straight region A.

[0163] The bending radius of the bending area gradually increases from the inner circle to the outer circle. The bending section of the positive electrode sheet 31a is larger than the bending section of the negative electrode sheet 32a on the inner side. The NP ratio (the ratio of the negative electrode active material content to the positive electrode active material content) at this position is small. More lithium ions are released from the positive electrode sheet 31a, and the lithium insertion sites of the negative electrode sheet 32a are insufficient. Lithium deposition occurs after the lithium ions combine with electrons. When lithium deposition is severe, lithium dendrites are formed, which will pierce the diaphragm 33, causing the positive electrode sheet 31a and the negative electrode sheet 32a to short-circuit.

[0164] At least a portion of the first functional layer 332 is located in the bending area, which can reduce the risk of puncturing the separator 33 in the bending area, reduce the risk of short circuit in the battery cell 10 , and improve the reliability of the battery cell 10 .

[0165] External thermal diffusion testing or external mitigation of high temperature effects on the separator 33 typically occurs in the outermost turns. To reduce the number of turns of the first functional layer 332 and the amount of the first functional layer 332 used, the first functional layer 332 can be provided on the substrate layer 331 of the outermost turns of the separator 33. In some embodiments, the electrode assembly 30 has a wound structure, and the first functional layer 332 is provided on the outermost N turns, where N does not exceed 20 and the number of turns of the separator 33 is greater than N.

[0166] The impact of the rapid temperature rise inside the battery 100 on the separator 33 typically occurs in the innermost turns. To reduce the number of turns of the first functional layer 332 and the amount of the first functional layer 332 used, the first functional layer 332 can be provided on the substrate layer 331 of the innermost turns of the separator 33. In some embodiments, the electrode assembly 30 has a wound structure, and the first functional layer 332 is provided in the innermost M turns, where M does not exceed 20 and the number of turns of the separator 33 is greater than M.

[0167] FIG13 is a schematic structural diagram of an electrode assembly 30 according to some other embodiments of the present application.

[0168] In order to further improve the performance of the diaphragm 33 and alleviate the risk of short circuit in the battery cell 10, in some embodiments, the substrate layer 331 has a second surface 3312 arranged opposite to the first surface 3311 in its thickness direction X, and the diaphragm 33 also includes a second functional layer 333, which is arranged on the second surface 3312.

[0169] It can be understood that the second functional layer 333 and the first functional layer 332 are respectively disposed on two opposite surfaces of the substrate layer 331 .

[0170] The second functional layer 333 has the same function as the first functional layer 332 . The second functional layer 333 can be made of the same material as the first functional layer 332 . The arrangement of the second functional layer 333 can be the same as or different from that of the first functional layer 332 , which will not be repeated here.

[0171] The second functional layer 333 can further improve the local heat resistance or puncture resistance of the separator 33 , alleviate the short circuit in the battery cell 10 , and improve the reliability of the battery cell 10 .

[0172] The embodiment of the present application further provides a battery 100 , which includes the battery cell 10 provided above.

[0173] An embodiment of the present application further provides an electrical device, which includes the battery cell 10 provided in the above embodiment or the battery 100 provided in the above embodiment, and the battery cell 10 or the battery 100 is used to supply power to the electrical device.

[0174] The present application also provides a battery cell 10, comprising an electrode assembly 30, comprising a first electrode sheet 31, a second electrode sheet 32, a first electrode tab 311, a second electrode tab 321, and a separator 33. The first electrode sheet 31 is a positive electrode sheet 31a, and the second electrode sheet 32 ​​is a negative electrode sheet 32a. The first electrode tab 311 is connected to one end of the first electrode sheet 31 in a first direction Z, and the second electrode tab 321 is connected to one end of the second electrode sheet 32 ​​in the first direction Z. The first electrode tab 311 and the second electrode tab 321 may be located on the same side or on opposite sides of the electrode. The diaphragm 33 is disposed between the first electrode piece 31 and the second electrode piece 32. The diaphragm 33 includes a substrate layer 331 and a first functional layer 332. The substrate layer 331 has a first surface 3311 in its thickness direction X. The first functional layer 332 is disposed on the first surface 3311. The substrate layer 331 has a first edge 3313 and a second edge 3314 that are opposite each other along the first direction Z. The first functional layer 332 is spaced apart from the first edge 3313, and the first functional layer 332 is spaced apart from the second edge 3314. A plurality of first functional layers 332 are provided, and the plurality of first functional layers 332 are spaced apart along the second direction Y, which is perpendicular to the first direction Z.

[0175] The present application also provides a battery cell 10, comprising an electrode assembly 30. The electrode assembly 30 includes a first electrode sheet 31, a second electrode sheet 32, a first electrode tab 311, a second electrode tab 321, and a separator 33. The first electrode sheet 31 is a positive electrode sheet 31a, and the second electrode sheet 32 ​​is a negative electrode sheet 32a. The first electrode tab 311 is connected to one end of the first electrode sheet 31 in a first direction Z, and the second electrode tab 321 is connected to one end of the second electrode sheet 32 ​​in the first direction Z. The first electrode tab 311 and the second electrode tab 321 are on the same side. The diaphragm 33 is disposed between the first electrode piece 31 and the second electrode piece 32. The diaphragm 33 includes a substrate layer 331 and a first functional layer 332. The substrate layer 331 has a first surface 3311 in its thickness direction X. The first functional layer 332 is disposed on the first surface 3311. The substrate layer 331 has a first edge 3313 and a second edge 3314 that are opposite each other along the first direction Z. The first electrode tab 311, the second electrode tab 321, and the first edge 3313 are located on the same side in the first direction Z. The first functional layer 332 extends to the first edge 3313 and is spaced apart from the second edge 3314. A plurality of first functional layers 332 are provided, and the plurality of first functional layers 332 are spaced apart along the second direction Y, which is perpendicular to the first direction Z.

[0176] The present application also provides a battery cell 10, which includes an electrode assembly 30. The electrode assembly 30 includes a first electrode sheet 31, a second electrode sheet 32, a first electrode tab 311, a second electrode tab 321, and a separator 33. The first electrode sheet 31 is a positive electrode sheet 31a, and the second electrode sheet 32 ​​is a negative electrode sheet 32a. The first electrode tab 311 is connected to one end of the first electrode sheet 31 in a first direction Z, and the second electrode tab 321 is connected to one end of the second electrode sheet 32 ​​in the first direction Z. The first electrode tab 311 and the second electrode tab 321 are on opposite sides. The diaphragm 33 is disposed between the first electrode piece 31 and the second electrode piece 32. The diaphragm 33 includes a substrate layer 331 and a first functional layer 332. The substrate layer 331 has a first surface 3311 in its thickness direction X. The first functional layer 332 is disposed on the first surface 3311. The substrate layer 331 has a first edge 3313 and a second edge 3314 that are opposite each other along a first direction Z. The first electrode tab 311 and the first edge 3313 are located on the same side of the first direction Z, while the second electrode tab 321 and the second edge 3314 are located on the same side of the first direction Z. The first functional layer 332 includes a first portion 3321 and a second portion 3322. The first portion 3321 and the second portion 3322 are spaced apart along the first direction Z. Along the first direction Z, the first portion 3321 extends to the first edge 3313, and the second portion 3322 extends to the second edge 3314. A plurality of first functional layers 332 are provided, and the plurality of first functional layers 332 are spaced apart along a second direction Y, which is perpendicular to the first direction Z.

[0177] The present application also provides a battery cell 10, which includes an electrode assembly 30. The electrode assembly 30 is a wound structure and flat. The electrode assembly 30 includes a straight region A and a bent region. The electrode assembly 30 includes a first electrode sheet 31, a second electrode sheet 32, and a separator 33. The first electrode sheet 31 is a positive electrode sheet 31a, and the second electrode sheet 32 ​​is a negative electrode sheet 32a. The separator 33 is disposed between the first electrode sheet 31 and the second electrode sheet 32. The separator 33 includes a substrate layer 331 and a first functional layer 332. The substrate layer 331 has a first surface 3311 in its thickness direction X. The first functional layer 332 is disposed on the first surface 3311. The first functional layer 332 is located in the straight region A or the bent region.

[0178] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0179] The above embodiments are intended only to illustrate the technical solutions of this application and are not intended to limit this application. Those skilled in the art will appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application are intended to be within the scope of protection of this application.

Claims

1. A battery cell, characterized in that: The electrode assembly includes a first electrode piece, a second electrode piece, and a diaphragm, wherein the first electrode piece and the second electrode piece have opposite polarities, and the diaphragm is disposed between the first electrode piece and the second electrode piece; The diaphragm includes a substrate layer and a first functional layer. The substrate layer has a first surface in a thickness direction thereof, and the first functional layer is disposed on the first surface.

2. The battery cell according to claim 1, wherein: The electrode assembly further includes a first electrode tab connected to one end of the first electrode piece in the first direction; Along the first direction, a size of the first functional layer is smaller than a size of the substrate layer.

3. The battery cell according to claim 2, characterized in that: Along the first direction, the size of the first functional layer is H1, and the size of the substrate layer is H2, satisfying 1 / 30≤H1 / H2≤29 / 30.

4. The battery cell according to claim 2 or 3, characterized in that: The substrate layer has a first edge and a second edge oppositely disposed along the first direction, and the first electrode tab and the first edge are located on the same side in the first direction; Wherein, along the first direction, the first functional layer and the second edge are arranged at intervals.

5. The battery cell according to claim 4, characterized in that Along the first direction, the first functional layer extends to the first edge.

6. The battery cell according to claim 5, characterized in that The electrode assembly further includes a second electrode tab connected to one end of the second electrode sheet in the first direction, and the first electrode tab and the second electrode tab are located on the same side in the first direction.

7. The battery cell according to claim 4 or 5, characterized in that: Along the first direction, the first functional layer is spaced apart from the first edge.

8. The battery cell according to any one of claims 2 to 7, characterized in that: The electrode assembly further includes a second electrode tab connected to one end of the second electrode sheet in the first direction, and the first electrode tab and the second electrode tab are located on opposite sides in the first direction; The substrate layer has a first edge and a second edge disposed opposite to each other along the first direction; The first functional layer includes a first portion and a second portion, the first portion and the second portion are spaced apart along the first direction, and along the first direction, the first portion extends to the first edge, and the second portion extends to the second edge.

9. The battery cell according to any one of claims 1 to 8, characterized in that: The electrode assembly further includes a first electrode tab connected to one end of the first electrode piece in the first direction; A plurality of the first functional layers are provided, and the plurality of the first functional layers are arranged at intervals along a second direction, and the second direction is perpendicular to the first direction.

10. The battery cell according to claim 9, characterized in that The electrode assembly is a wound structure, and the second direction is the winding direction of the electrode assembly.

11. The battery cell according to claim 10, characterized in that The electrode assembly is flat and includes a straight area and a bent area. At least a portion of the first functional layer is located in the straight area.

12. The battery cell according to claim 10 or 11, characterized in that: The electrode assembly is flat and includes a straight area and a bending area, and at least a portion of the first functional layer is located in the bending area.

13. The battery cell according to any one of claims 1 to 12, characterized in that: The material of the first functional layer includes one of aluminum oxide, silicon dioxide, boehmite and titanium dioxide.

14. The battery cell according to any one of claims 1 to 13, characterized in that: The substrate layer has a second surface disposed opposite to the first surface in a thickness direction thereof. The separator further includes a second functional layer disposed on the second surface.

15. A battery, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 14.

16. An electrical device, characterized in that: The battery cell according to any one of claims 1 to 14 or the battery according to claim 15 is used to supply power to the electrical device.

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