Battery monomer, positive plate, battery device and power utilization device

Abstract

The utility model provides a battery monomer, a positive plate, a battery device and a power utilization device. The battery cell includes: a case; the electrode assembly is arranged in the shell, the electrode assembly comprises a positive plate, the positive plate comprises a current collector and an active material layer, the current collector comprises a current collecting part, an empty foil part and a tab which are connected with one another, the active material layer is arranged on the current collecting part, the empty foil part is arranged between the current collecting part and the tab, and the electrode assembly further comprises an isolating layer, the isolation layer covers at least part of the empty foil part.

Description

Technical Field

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

[0002] Batteries are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes and power tools, etc.

[0003] In the related art, battery cells are prone to internal short circuits due to damage to separators, and the reliability of battery cells still needs to be improved. Utility Model Content

[0004] In view of the above problems, the present application provides a battery cell, a positive electrode sheet, a battery device and an electrical device, which can improve the problem of internal short circuit caused by damage to the separator and insufficient reliability of the battery cell.

[0005] In a first aspect, an embodiment of the present application provides a battery cell, comprising: a shell; an electrode assembly, arranged in the shell, the electrode assembly including a positive electrode sheet, the positive electrode sheet including a current collector and an active material layer, the current collector including a current collecting portion, a hollow foil portion and a pole tab connected to each other, the active material layer being arranged in the current collecting portion, and the hollow foil portion being arranged between the current collecting portion and the pole tab, wherein the electrode assembly also includes an isolation layer, and the isolation layer covers at least part of the hollow foil portion.

[0006] In the solution of the embodiment of the present application, the battery cell includes a shell and an electrode assembly, the electrode assembly is accommodated in the shell, the electrode assembly includes a positive electrode sheet, the positive electrode sheet includes a current collector and an active material layer, the current collector includes a current collecting part, a hollow foil part and a pole ear that are interconnected, the active material layer is arranged in the current collecting part, the hollow foil part is arranged between the current collecting part and the pole ear, and the electrode assembly also includes an isolation layer. By covering the isolation layer on at least part of the hollow foil part, the isolation layer can block the burrs on the hollow foil part, so as to improve the problem that the burrs on the hollow foil part pierce the isolation piece and cause the adjacent positive and negative electrode sheets to short-circuit, thereby improving the reliability of the battery cell.

[0007] In some embodiments, the isolation layer is disposed on at least one side of the hollow foil portion in a thickness direction.

[0008] In the solution of the embodiment of the present application, the isolation layer is arranged on at least one side of the hollow foil portion in the thickness direction, so that the isolation layer can block the burrs covering the hollow foil portion in the thickness direction, thereby reducing the risk of the burrs in the thickness direction of the hollow foil portion piercing the isolation member and causing a short circuit in the battery cell.

[0009] In some embodiments, the hollow foil portion includes end surfaces on both sides in the thickness direction thereof and side surfaces connected to the two end surfaces, and the isolation layer is provided on part of the side surfaces.

[0010] In the solution of the embodiment of the present application, the hollow foil portion includes end faces on both sides thereof in the thickness direction and side faces connected to the two end faces, and the isolation layer is arranged on some side faces so that the isolation layer can block the burrs covering the side faces of the hollow foil portion, thereby reducing the risk of the side burrs piercing the isolation member and causing a short circuit in the battery cell.

[0011] In some embodiments, the isolation layer includes a first end and a second end that are arranged opposite to each other, the first end is arranged on the surface of the hollow foil portion in the thickness direction, and the second end extends out of the hollow foil portion in a direction away from the current collecting portion. The two isolation layers are arranged on both sides of the positive electrode sheet, and the second ends of the two isolation layers are connected to each other.

[0012] In the solution of the embodiment of the present application, the isolation layer includes a first end and a second end arranged opposite to each other, the first end is arranged on the surface of the hollow foil portion in the thickness direction, so that the first end can block the burrs covering the hollow foil portion in the thickness direction, and the second end extends out of the hollow foil portion. The second ends of the two isolation layers arranged on both sides of the positive electrode sheet are connected to each other, that is, the burrs on the side and the isolation member can be separated by the isolation layer, which reduces the difficulty of setting the isolation layer.

[0013] In some embodiments, at least a portion of the second end extends to an end of the tab adjacent to the hollow foil portion.

[0014] In the solution of the embodiment of the present application, at least part of the second end extends to the end of the pole ear close to the empty foil portion, and the part of the isolation layer extending to the pole ear can reinforce the pole ear, reduce the risk of cracking at the root of the pole ear, and increase the contact area between the isolation layer and the current collector, thereby improving the connection strength between the isolation layer and the current collector.

[0015] In some embodiments, the minimum dimensions between the active material layer and the electrode tab on both sides of the current collector in the thickness direction are different, and two isolation layers are arranged on both sides of the empty foil portion. One end of the isolation layer is connected to the empty foil portion, and the other end is connected to the active material layer. The isolation layers arranged on both sides of the empty foil portion have the same extension dimensions in the current collector.

[0016] In the solution of the embodiment of the present application, the minimum dimensions between the active material layer and the electrode ear arranged on both sides in the thickness direction of the current collector are different, and two isolation layers are arranged on both sides of the empty foil portion, one end of the isolation layer is connected to the empty foil portion, and the other end is connected to the active material layer. The isolation layers arranged on both sides of the empty foil portion have the same extension dimensions in the current collector. The isolation layers can be used to balance the lengths of the active material layers on both sides to improve the problem of lithium deposition on the positive electrode sheet due to the interlacing of the active material layers on both sides.

[0017] In some embodiments, both separation layers extend to the side of the active material layer facing away from the current collector.

[0018] In the solution of the embodiment of the present application, both isolation layers extend to the side of the active material layer away from the current collector, which can improve the connection reliability between the isolation layer and the active material layer and reduce the difficulty of setting the isolation layer.

[0019] In some embodiments, along the thickness direction of the positive electrode sheet, the maximum dimension from the separation layer to the current collector is smaller than the maximum dimension from the active material layer to the current collector.

[0020] In the solution of the embodiment of the present application, along the thickness direction of the positive electrode sheet, the maximum dimension from the isolation layer to the current collector is smaller than the maximum dimension from the active material layer to the current collector, so as to improve the problem of bulging of the electrode assembly caused by the isolation layer being set too high.

[0021] In some embodiments, the isolation layer is disposed at an end of the hollow foil portion facing away from the current collecting portion and extends toward the current collecting portion.

[0022] In the solution of the embodiment of the present application, after the foil is die-cut, burrs are more likely to form on the end of the empty foil portion facing away from the current collecting portion. Therefore, an isolation layer is arranged at the end of the empty foil portion facing away from the current collecting portion and extends toward the current collecting portion. This can save the production cost of the battery cell while effectively covering the burrs with the isolation layer.

[0023] In some embodiments, the isolation layer is made of an insulating material so that the isolation layer and the current collector can be insulated from each other.

[0024] In the embodiment of the present application, the isolation layer is made of an insulating material, and the isolation layer and the current collector are insulated from each other, so that when the isolation member is damaged, the isolation layer can still insulate adjacent positive and negative electrodes from each other, thereby improving the reliability of the battery cell.

[0025] In a second aspect, an embodiment of the present application provides a positive electrode sheet, which is applied to the battery cell of the embodiment of the first aspect above. The positive electrode sheet includes a current collector and an active material layer. The current collector includes a current collecting portion, a hollow foil portion and a pole tab that are interconnected. The active material layer is arranged in the current collecting portion, and the hollow foil portion is arranged between the current collecting portion and the pole tab. The electrode assembly also includes an isolation layer, which covers at least part of the hollow foil portion.

[0026] In the solution of the embodiment of the present application, the positive electrode sheet includes a current collector and an active material layer, the current collector includes a current collecting part, a hollow foil part and a pole ear that are interconnected, the active material layer is arranged on the current collecting part, and the hollow foil part is arranged between the current collecting part and the pole ear, and the electrode assembly also includes an isolation layer. By covering the isolation layer on at least part of the hollow foil part, the isolation layer can block the burrs on the hollow foil part, so as to improve the problem that the burrs on the hollow foil part pierce the isolation part and cause the adjacent positive and negative electrode sheets to contact and short-circuit, thereby improving the reliability of the battery cell.

[0027] In some embodiments, the isolation layer is disposed on at least one side of the hollow foil portion in a thickness direction.

[0028] In the solution of the embodiment of the present application, the isolation layer is arranged on at least one side of the hollow foil portion in the thickness direction, so that the isolation layer can block the burrs covering the hollow foil portion in the thickness direction, thereby reducing the risk of the burrs in the thickness direction of the hollow foil portion piercing the isolation member and causing a short circuit in the battery cell.

[0029] In some embodiments, the hollow foil portion includes end surfaces on both sides in the thickness direction thereof and side surfaces connected to the two end surfaces, and the isolation layer is provided on part of the side surfaces.

[0030] In the solution of the embodiment of the present application, the hollow foil portion includes end faces on both sides thereof in the thickness direction and side faces connected to the two end faces, and the isolation layer is arranged on some side faces so that the isolation layer can block the burrs covering the side faces of the hollow foil portion, thereby reducing the risk of the side burrs piercing the isolation member and causing a short circuit in the battery cell.

[0031] In some embodiments, the minimum dimensions between the active material layer and the electrode tab on both sides of the current collector in the thickness direction are different, and two isolation layers are arranged on both sides of the empty foil portion. One end of the isolation layer is connected to the empty foil portion, and the other end is connected to the active material layer. The isolation layers arranged on both sides of the empty foil portion have the same extension dimensions in the current collector.

[0032] In the solution of the embodiment of the present application, the minimum dimensions between the active material layer and the electrode ear arranged on both sides in the thickness direction of the current collector are different, and two isolation layers are arranged on both sides of the empty foil portion, one end of the isolation layer is connected to the empty foil portion, and the other end is connected to the active material layer. The isolation layers arranged on both sides of the empty foil portion have the same extension dimensions in the current collector. The isolation layers can be used to balance the lengths of the active material layers on both sides to improve the problem of lithium deposition on the positive electrode sheet due to the interlacing of the active material layers on both sides.

[0033] In a third aspect, an embodiment of the present application provides a battery device comprising the battery cell of the embodiment of the first aspect described above.

[0034] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising the battery device of the embodiment of the third aspect described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0036] Figure 1 is a structural schematic diagram of a vehicle provided in one embodiment of the present application;

[0037] Figure 2 is a structural diagram of a battery device provided in one embodiment of the present application;

[0038] Figure 3 This is a schematic structural diagram of a battery module provided in one embodiment of the application;

[0039] Figure 4 is an exploded view of a battery cell provided in one embodiment of the present application;

[0040] Figure 5 This is a schematic diagram of a partial structure of an electrode assembly of a battery cell provided in one embodiment of the present application;

[0041] Figure 6 This is a schematic structural diagram of a positive electrode sheet of a battery cell provided in one embodiment of the present application;

[0042] Figure 7 yes Figure 6 Cross-section at AA;

[0043] Figure 8 yes Figure 6 Cross-section at the middle BB;

[0044] Figure 9 is a structural schematic diagram of a positive electrode sheet of a battery cell provided in another embodiment of the present application;

[0045] Figure 10 In one embodiment of the present application Figure 9 Cross-section at CC;

[0046] Figure 11 In another embodiment of the present application Figure 9 Cross-sectional view at CC.

[0047] Description of reference numerals:

[0048] 1. Vehicle; 101. Motor; 102. Controller;

[0049] 2. Battery device; 201. Battery module; 202. Box; 2021. First box; 2022. Second box; 3. Battery cell; 4. Housing; 5. Electrode assembly; 6. Top cover assembly;

[0050] 7. Positive electrode sheet; 71. Current collector; 72. Active material layer; 711. Current collector; 712. Hollow foil; 713. Tab; 7121. End face; 7122. Side face; 721. Base section; 722. Thinned section;

[0051] 51, isolation layer; 511, first end; 512, second end;

[0052] 8. Negative electrode; 9. Separator. DETAILED DESCRIPTION

[0053] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0054] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the embodiments of the present application should have the common meanings understood by technicians in the field to which the embodiments of the present application belong.

[0055] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.

[0056] In addition, the technical terms "first," "second," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. In the description of the embodiments of the present application, the meaning of "plurality" is more than two, unless otherwise specifically defined.

[0057] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0058] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0059] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0060] In this application, battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, and the embodiments of this application are not limited thereto. Battery cells may be cylindrical, flat, rectangular, or in other shapes, and the embodiments of this application are not limited thereto.

[0061] 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 that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0062] Battery cells are prone to internal short circuits due to damage to separators.

[0063] During the electrode processing process, burrs are easily generated on the surface of the current collector after die-cutting. During the winding, pressing and even use of the electrode, these burrs can easily puncture the separator and cause a short circuit between the positive and negative electrodes.

[0064] Based on the above problems, the battery cell includes a shell and an electrode assembly, the electrode assembly is accommodated in the shell, the electrode assembly includes a pole piece, the pole piece includes a current collector and an active material layer, the current collector includes a current collecting part, a hollow foil part and a pole ear that are interconnected, the active material layer is arranged in the current collecting part, the hollow foil part is arranged between the current collecting part and the pole ear, and the electrode assembly also includes an isolation layer. By covering the isolation layer on at least part of the hollow foil part, the isolation layer can block the burrs on the hollow foil part, so as to improve the problem that the burrs on the hollow foil part pierce the isolation piece and cause the adjacent pole pieces to short-circuit, thereby improving the reliability of the battery cell.

[0065] The technical solutions described in the embodiments of the present application are applicable to battery devices and electrical devices using battery devices.

[0066] A battery cell includes an electrode assembly and electrolyte within a housing. The electrodes include a positive electrode and a negative electrode. The electrode assembly also includes a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrodes.

[0067] Specifically, a positive electrode sheet includes a positive current collector and a positive active material layer, which is coated on the surface of the positive current collector. The positive current collector includes a positive current collector portion and a positive tab connected to the positive current collector portion. The positive current collector portion is coated with the positive active material layer, while the positive tab is not. For lithium-ion batteries, for example, the positive current collector can be aluminum or a composite material containing an aluminum coating. The positive active material layer includes a positive active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. A negative electrode sheet includes a negative current collector and a negative active material layer, which is coated on the surface of the negative current collector. The negative current collector includes a negative current collector portion and a negative tab connected to the negative current collector portion. The negative current collector portion is coated with the negative active material layer, while the negative tab is not. The negative current collector can be copper or a composite material containing a copper coating. The negative active material layer includes a negative active material, which can be carbon or silicon, for example. The material of the spacer can be PP (polypropylene) or PE (polyethylene).

[0068] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0069] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0070] The battery cells may be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc., and the present invention does not limit this. The battery cells may be cylindrical, flat, rectangular, or other shapes, and the present invention does not limit this.

[0071] The battery device 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 device referred to in this application may include a battery module or battery pack. A battery pack generally includes a casing for enclosing one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0072] It should be understood that the technical solutions described in the embodiments of the present application are not limited to the battery devices and electrical equipment described above, but can also be applied to all battery devices including a box and electrical equipment using the battery devices. However, for the sake of simplicity, the following embodiments are explained using electric vehicles as an example.

[0073] Please refer to Figure 1 , Figure 1 A schematic structural diagram of a vehicle 1 provided for some embodiments of the present application. The vehicle 1 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery device 2 is provided inside the vehicle 1, and the battery device 2 may be provided at the bottom, head or tail of the vehicle 1. The battery device 2 may be used to power the vehicle 1, for example, the battery device 2 may serve as an operating power source for the vehicle 1. The vehicle 1 may further include a controller 102 and a motor 101, and the controller 102 is used to control the battery to power the motor 101, for example, for starting, navigating and operating power requirements of the vehicle 1 during driving.

[0074] In some embodiments of the present application, the battery device 2 can serve not only as an operating power source for the vehicle 1 , but also as a driving power source for the vehicle 1 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1 .

[0075] Figure 2 A schematic structural diagram of a battery device according to an embodiment of the present application is shown.

[0076] The battery device 2 mentioned in the embodiment of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include multiple battery cells 3, and the multiple battery cells 3 are connected in series, parallel or mixed via a busbar.

[0077] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells 3 .

[0078] As an example, the battery cell assembly may be a battery module 201, wherein the battery module 201 is formed by arranging and fixing a plurality of battery cells 3 to form an independent module. As an example, the battery module 201 may be formed by bundling the plurality of battery cells 3 with a cable tie.

[0079] In some embodiments, the battery device may be a battery pack, which includes a case 202 and one or more battery cell assemblies, wherein the battery cell assemblies are housed in the case 202 .

[0080] As an example, the battery cell assembly may be a battery module 201 , and the battery cell assembly may be accommodated in the box by fixing the battery module 201 in the box.

[0081] As an example, the battery cell assembly may also be housed in the box body 202 by directly fixing the plurality of battery cells 3 to the box body 202 .

[0082] As an example, housing 202 may include a first housing 2021 and a second housing 2022. The first housing 2021 and the second housing 2022 engage to form an enclosed space within housing 202 for accommodating battery cell assemblies. Enclosed here means covered or closed, and can be either sealed or unsealed. First housing 2021 may be a top cover or a bottom plate.

[0083] As an example, the box body 202 may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that a closed space is formed inside the box body 202 to accommodate the battery cell assembly.

[0084] In some embodiments, the box 202 can be used as part of the chassis structure of the vehicle. For example, part of the box 202 can become at least a part of the floor of the vehicle, or part of the box 202 can become at least a part of the crossbeam and longitudinal beam of the vehicle.

[0085] Figure 3 A schematic structural diagram of a battery module 201 according to an embodiment of the present application is shown.

[0086] In some embodiments, as Figure 2 and Figure 3 As shown, there are multiple battery cells 3, which are first connected in series, in parallel, or in series to form a battery module 201. The multiple battery modules 201 are then connected in series, in parallel, or in series to form a whole, and are accommodated in a box 202.

[0087] The multiple battery cells 3 in the battery module 201 can be electrically connected via a busbar component to achieve parallel connection, series connection, or mixed connection of the multiple battery cells 3 in the battery module 201 .

[0088] In the present application, the battery cell 3 may include a lithium-ion battery cell, a sodium-ion battery cell, a magnesium-ion battery cell, etc., which is not limited in the embodiments of the present application.

[0089] Figure 4 : is an exploded view of a battery cell provided in one embodiment of the present application. Battery cell 3 refers to the smallest unit that makes up a battery. Figure 4 The battery cell 3 includes a top cover assembly 6, a shell 4 and an electrode assembly 5.

[0090] The electrode assembly 5 is a component in the battery cell 3 where electrochemical reactions occur. One or more electrode assemblies 5 may be contained in the housing 4. The electrode assembly 5 is mainly formed by winding or stacking electrode sheets, which are divided into positive electrode sheets and negative electrode sheets, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet with active materials constitute the electrode body, and the parts of the positive electrode sheet and the negative electrode sheet without active materials each constitute the electrode ear. The positive electrode ear and the negative electrode ear may be located together at one end of the electrode body or respectively at both ends of the electrode body. During the charge and discharge process of the battery cell 3, the positive electrode active material and the negative electrode active material react with the electrolyte, and the electrode ears connect the electrode terminals to form a current loop.

[0091] The electrode assembly 5 may be a wound structure, a laminated structure, or a mixed structure of wound and laminated structures.

[0092] In some embodiments, the electrode assembly 5 is a wound structure in which the positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0093] In some embodiments, the electrode assembly 5 has a laminated structure. As an example, multiple positive and negative electrode sheets can be provided, and the multiple positive and negative electrode sheets can be alternately stacked. Multiple separators can be provided and respectively disposed between any adjacent positive or negative electrode sheets. Alternatively, the separators can be provided continuously and folded between any adjacent positive or negative electrode sheets.

[0094] In some embodiments, the shape of the electrode assembly 5 can be cylindrical, flat, or polygonal.

[0095] In some embodiments, the electrode assembly 5 is provided with tabs, which can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0096] The battery cell 3 may include a shell 4. The shell 4 is a component used to cooperate with the top cover assembly 6 to form an internal environment of the battery cell 3, wherein the internal environment formed can be used to accommodate the electrode assembly 5, the electrolyte (not shown in the figure) and other components. The shell 4 can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell) or an aluminum-plastic film, etc. In some embodiments, the shell 4 can be a sealed structure or a non-sealed structure. As an example, when the shell 4 is a non-sealed structure, the shell 4 plays a role in protecting the electrode assembly 5, and a sealing bag is further included between the shell 4 and the electrode assembly 5, and the sealing bag is used to encapsulate the electrode assembly and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating member or an aluminum-plastic film. When the shell 4 is a sealed structure, it is used to encapsulate components such as the electrode assembly 5 and the electrolyte.

[0097] As an example, the battery cell 3 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, and a polygonal battery. The polygonal battery is, for example, a hexagonal battery, etc. There is no special limitation in this application.

[0098] The housing 4 and the top cover assembly 6 can be separate components. One or more openings can be provided on the housing 4, and one or more top cover assemblies 6 cover the openings to form the internal environment of the battery cell 3. Alternatively, the top cover assembly 6 and the housing 4 can be integrated. Optionally, the top cover assembly 6 and the housing 4 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 4 needs to be enclosed, the top cover assembly 6 is then placed to cover the housing 4.

[0099] See also Figure 5 、 Figure 6 and Figure 7 , Figure 5 This is a schematic diagram of a partial structure of an electrode assembly of a battery cell provided in one embodiment of the present application; Figure 6 This is a schematic structural diagram of a positive electrode sheet of a battery cell provided in one embodiment of the present application; Figure 7 yes Figure 6 Cross-section at AA in the middle.

[0100] First, as Figures 4 to 7 An embodiment of the present application provides a battery cell 3, which includes a shell 4 and an electrode assembly 5. The electrode assembly 5 is arranged in the shell 4, and the electrode assembly 5 includes a positive electrode sheet 7. The positive electrode sheet 7 includes a current collector 71 and an active material layer 72. The current collector 71 includes a current collecting portion 711, a hollow foil portion 712 and a pole ear 713 that are interconnected. The active material layer 72 is arranged in the current collecting portion 711, and the hollow foil portion 712 is arranged between the current collecting portion 711 and the pole ear 713. The electrode assembly 5 also includes an isolation layer 51, and the isolation layer 51 covers at least part of the hollow foil portion 712.

[0101] In the solution of the embodiment of the present application, the battery cell 3 includes a shell 4 and an electrode assembly 5, the electrode assembly 5 is accommodated in the shell 4, the electrode assembly 5 includes a positive electrode sheet 7, the positive electrode sheet 7 includes a current collector 71 and an active material layer 72, the current collector 71 includes a current collector portion 711, a hollow foil portion 712 and a pole ear 713 connected to each other, the active material layer 72 is arranged in the current collector portion 711, and the hollow foil portion 712 is arranged between the current collector portion 711 and the pole ear 713, and the electrode assembly 5 also includes an isolation layer 51. By covering the isolation layer 51 on at least part of the hollow foil portion 712, the isolation layer 51 can block the burrs located on the hollow foil portion 712, so as to improve the problem that the burrs of the hollow foil portion 712 pierce the isolation member 9 and cause the adjacent positive and negative electrode sheets 8 to contact and short-circuit, thereby improving the reliability of the battery cell 3.

[0102] The electrode assembly 5 includes a positive electrode sheet 7 and a negative electrode sheet 8 stacked or wound together, and a separator 9 insulated between adjacent positive and negative electrode sheets 8 .

[0103] The current collector 71 includes a current collecting portion 711, a hollow foil portion 712, and a tab 713, which are interconnected. The current collecting portion 711 is used to support the active material layer 72. The hollow foil portion 712 corresponds to the overhang area of ​​the negative electrode sheet 8. The tab 713 is used to output current to the outside world. The tab 713 can be obtained by die-cutting the current collector 71 or welded to the hollow foil portion 712.

[0104] There are burrs on the outer surface of the hollow foil portion 712, and the isolation layer 51 covers the outer surface of the hollow foil portion 712. Then the isolation layer 51 can be a patch arranged on the hollow foil portion 712, the patch covers the burrs, the burrs cannot extend out of the isolation layer 51, and the burrs are smooth and sharp; or the isolation layer 51 is a colloid, and the burrs are completely sealed in the colloid layer, or the burrs are partially sealed in the colloid layer to shorten the length of the burrs, so as to reduce the risk of the burrs piercing the isolation member 9 under the action of external force.

[0105] The isolation layer 51 covers the empty foil portion 712, so the isolation layer 51 and the current collector 71 are independent of each other, and the isolation layer 51 can be directly bonded to the empty foil portion 712 to improve the stability of the isolation layer 51; or the isolation layer 51 and the empty foil portion 712 are partially connected or spaced apart, and the isolation layer 51 is located between the insulating member 9 and the empty foil portion 712, and the positive projection of the isolation layer 51 on the current collector 71 is located on the empty foil portion 712.

[0106] Optionally, the isolation layer 51 covers the entire outer surface of the hollow foil portion 712 , so that the isolation layer 51 can shield the burrs of the entire hollow foil portion 712 .

[0107] The width of the isolation layer 51 can be flexibly designed. Optionally, the width D of the isolation layer 51 is between 3 mm and 10 mm. For example, the width D of the isolation layer 51 is 3 mm, 5 mm, 8 mm, or 10 mm.

[0108] Optionally, the thickness of the isolation layer 51 is between 9 μm and 30 μm. Exemplarily, the thickness of the isolation layer 51 is 9 μm, 20 μm, or 30 μm.

[0109] In some embodiments, as Figures 5 to 7 As shown, the isolation layer 51 is made of an insulating material so that the isolation layer 51 and the current collector 71 can be insulated from each other.

[0110] In these embodiments, the isolation layer 51 is made of an insulating material, and the isolation layer 51 and the current collector 71 are insulated from each other, so that when the separator 9 is damaged, the isolation layer 51 can still insulate the adjacent positive and negative electrode sheets 8 from each other, thereby improving the reliability of the battery cell 3.

[0111] Optionally, the isolation layer 51 may be made of polypropylene, polyvinyl alcohol, polyvinyl ketone, polymethacrylate, polyvinylidene fluoride, nano-silica gel, polyacrylonitrile, polyacrylic acid, styrene-butadiene rubber, etc.

[0112] Optionally, the isolation layer 51 may be an insulating adhesive layer or insulating adhesive paper.

[0113] For example, the base material of the insulating tape is polypropylene with a thickness of 10 μm; the adhesive layer is made of polyacrylate with a thickness of 3 μm; the total thickness of the insulating tape is 13 μm and the width is 8 mm.

[0114] Exemplarily, the preparation process of the positive electrode sheet 7 can be to uniformly mix the positive electrode active material LiFePO4 (LFP), the binder polyvinylidene fluoride (PVDF) and the conductive carbon black (Super P) in a mass ratio of LPF:PVDF:Super P=95:3:2, and disperse the mixed slurry using 1-methyl-2-pyrrolidone (NMP) as a solvent, apply the obtained positive electrode slurry on both sides of the aluminum foil, and then glue it after drying, rolling, die-cutting and slitting; and stick the insulating tape on the die-cut edge.

[0115] Optionally, the isolation layer 51 remains stable in the electrolyte, and after being immersed in the electrolyte for 1000 hours, the peel strength requirement is 15 to 20 N / m. Exemplary testing methods include using an insulating tape with a thickness of 13 μm and a width of 8 mm to stick on an aluminum foil with a thickness of 13 μm, soaking it in a 70°C electrolyte for 200 hours, 400 hours, 600 hours, 800 hours, and 1000 hours, and then taking it out to test its peel strength; using a high-speed rail tensile testing machine, the soaked sample is adhered to a stainless steel plate with double-sided tape, with the side of the insulating tape facing outward and compacted with a roller, and the entire sample is fixed on the tensile testing machine; using the tensile testing machine, clamp one end of the tape upward at 180° and pull the tape up at a speed of 50 mm / min until the tape is completely peeled off from the aluminum foil, and record the displacement and force during the process.

[0116] Optionally, the isolation layer 51 does not break down under a voltage of 200 V, and the resistance value is greater than 9999 MΩ.

[0117] Optionally, the isolation layer 51 has good puncture strength, greater than 300 gf. For example, the test method is to use a 50 mm x 50 mm piece of insulating tape with a thickness of 13 μm and a puncture tester with a 1 mm diameter steel needle, and record the force required to puncture the insulating tape at a speed of 50 mm / min.

[0118] In some embodiments, as Figure 6 and Figure 7 As shown, the isolation layer 51 is provided on at least one side of the hollow foil portion 712 in the thickness direction.

[0119] In these embodiments, the isolation layer 51 is arranged on at least one side of the hollow foil portion 712 in the thickness direction, so that the isolation layer 51 can block the burrs covering the hollow foil portion 712 in the thickness direction, thereby reducing the risk of the burrs in the thickness direction of the hollow foil portion 712 piercing the isolation member 9 and causing a short circuit in the battery cell 3.

[0120] Optionally, the isolation layer 51 is provided on both sides of the hollow foil portion 712 in the thickness direction to increase the coverage area of ​​the isolation layer 51 on the hollow foil portion 712 and improve the effect of the isolation layer 51 in covering the burrs.

[0121] Optionally, the isolation layer 51 covers the entire surface of the hollow foil portion 712 in the thickness direction, so as to increase the coverage area of ​​the isolation layer 51 on the hollow foil portion 712 and improve the effect of the isolation layer 51 in covering the burrs.

[0122] In some embodiments, as Figure 6 and Figure 7 As shown, the hollow foil portion 712 includes end surfaces 7121 on both sides in the thickness direction thereof and side surfaces 7122 connected to the two end surfaces 7121 , and the isolation layer 51 is provided on part of the side surfaces 7122 .

[0123] In these embodiments, the hollow foil portion 712 includes end faces 7121 on both sides thereof in the thickness direction and side faces 7122 connected to the two end faces 7121. The isolation layer 51 is arranged on part of the side faces 7122 so that the isolation layer 51 can block the burrs covering the side faces 7122 of the hollow foil portion 712, thereby reducing the risk of the burrs on the side faces 7122 piercing the isolation member 9 and causing a short circuit in the battery cell 3.

[0124] Optionally, the tabs 713 are die-cut from foil, and the tabs 713 extend from a portion of the side surface 7122 of the hollow foil portion 712 . The positive electrode sheet 7 includes a plurality of tabs 713 spaced apart, and the isolation layer 51 is disposed on a portion of the side surface 7122 between adjacent tabs 713 .

[0125] Optionally, the isolation layer 51 covers the entire exposed side surface 7122 to increase the coverage area of ​​the isolation layer 51 on the hollow foil portion 712 and improve the effect of the isolation layer 51 in covering the burrs.

[0126] Optionally, the isolation layer 51 covers the side surface 7122 and the two end surfaces 7121 to increase the coverage area of ​​the isolation layer 51 on the hollow foil portion 712 and improve the effect of the isolation layer 51 in covering the burrs.

[0127] Optionally, the isolation layer 51 provided on the end face 7121 and the side face 7122 is integrally formed to reduce the difficulty of connecting the isolation layer 51 on the side face 7122 and the side face 7122, or the isolation layer 51 provided on the end face 7121 and the side face 7122 is respectively connected to the current collector 71 to facilitate adjustment of the size of the isolation layer 51 at the side face 7122 and the end face 7121.

[0128] See also Figure 8 , Figure 8 yes Figure 6 Cross-section at BB.

[0129] In some embodiments, as Figures 5 to 8 As shown, the isolation layer 51 includes a first end 511 and a second end 512 that are arranged opposite to each other. The first end 511 is arranged on the surface of the hollow foil portion 712 in the thickness direction, and the second end 512 extends from the hollow foil portion 712 in a direction away from the current collecting portion 711. The two isolation layers 51 are arranged on both sides of the positive electrode sheet 7, and the second ends 512 of the two isolation layers 51 are connected to each other.

[0130] In these embodiments, the isolation layer 51 includes a first end 511 and a second end 512 that are relatively arranged. The first end 511 is arranged on the surface of the hollow foil portion 712 in the thickness direction, so that the first end 511 can block the burrs covering the hollow foil portion 712 in the thickness direction, and the second end 512 extends out of the hollow foil portion 712. The second ends 512 of the two isolation layers 51 arranged on both sides of the positive electrode sheet 7 are connected to each other, that is, the burrs on the side 7122 and the isolation member 9 can be separated by the isolation layer 51, which reduces the difficulty of setting the isolation layer 51.

[0131] Relatively speaking, the surface area of ​​the hollow foil portion 712 in the thickness direction is larger than the surface area of ​​the side surface 7122. Therefore, the side surface 7122 and the isolation member 9 are separated by connecting the second ends 512 extending out of the hollow foil portion 712 to each other. Compared with the method of separately sticking the isolation layer 51 on the side surface 7122, the setting difficulty is lower.

[0132] An isolation layer 51 is respectively provided at both ends of the empty foil portion 712, and the first end 511 of the isolation layer 51 is bonded to the surface of the empty foil portion 712 in the thickness direction, and the first end 511 of the isolation layer 51 is separated from the isolation member 9 and the surface of the empty foil portion 712 in the thickness direction, so as to reduce the risk of burrs on the surface of the empty foil portion 712 in the thickness direction piercing the isolation member 9; the second end 512 extends toward the pole ear 713 and protrudes from the empty foil portion 712, and the two second ends 512 connected to each other are separated from the isolation member 9 and the side 7122 of the empty foil portion 712, so as to reduce the risk of burrs on the side 7122 piercing the isolation member 9.

[0133] Specifically, the extension dimension of the second end 512 is smaller than the extension dimension of the tab 713 , a plurality of tabs 713 are spaced apart on the side 7122 , and portions of the second end 512 of the isolation layer 51 between adjacent tabs 713 are connected to each other.

[0134] In some embodiments, as Figure 6 and Figure 8 As shown, at least a portion of the second end 512 extends to an end of the tab 713 close to the hollow foil portion 712 .

[0135] In these embodiments, at least a portion of the second end 512 extends to one end of the pole tab 713 close to the empty foil portion 712. The portion of the isolation layer 51 extending to the pole tab 713 can reinforce the pole tab 713, reduce the risk of cracking at the root of the pole tab 713, and increase the contact area between the isolation layer 51 and the current collector 71, thereby improving the connection strength between the isolation layer 51 and the current collector 71.

[0136] Multiple tabs 713 are spaced apart on the side surface 7122. A portion of the second end 512 extending beyond the hollow foil portion 712 is bonded to adjacent tabs 713, while another portion extends to the base of the tab 713 to reinforce the tab 713 and reduce the risk of damage during bending. The extent of the second end 512 extending beyond the tab 713 can be flexibly designed.

[0137] In some embodiments, as Figure 6 and Figure 8 As shown, the isolation layer 51 is provided at one end of the hollow foil portion 712 away from the current collecting portion 711 and extends toward the current collecting portion 711 .

[0138] In these embodiments, after the foil is die-cut, burrs are more likely to form on the end of the empty foil portion 712 facing away from the current collecting portion 711. Therefore, the isolation layer 51 is arranged at the end of the empty foil portion 712 facing away from the current collecting portion 711 and extends toward the current collecting portion 711. This can save the production cost of the battery cell 3 while effectively covering the burrs with the isolation layer 51.

[0139] After the foil is die-cut, burrs are more likely to form on the edge of the current collector 71. Therefore, the isolation layer 51 is set at the end of the empty foil portion away from the current collecting portion 711 and extends toward the current collecting portion 711. In this way, the burrs and the isolation member 9 can be effectively isolated by the isolation layer 51, and the size of the isolation layer 51 is reduced, thereby reducing the cost of the battery cell 3.

[0140] Exemplarily, the isolation layer 51 covers the side surface 7122 and extends from one end of the end surface 7121 close to the electrode tab 713 toward the current collecting portion 711 .

[0141] See also Figure 9 、 Figure 10 and Figure 11 , Figure 9 is a structural schematic diagram of a positive electrode sheet of a battery cell provided in another embodiment of the present application; Figure 10 In one embodiment of the present application Figure 9 Cross-section at CC; Figure 11 In another embodiment of the present application Figure 9 Cross-sectional view at CC.

[0142] In some embodiments, as Figure 5 、 Figures 9 to 11 As shown, the minimum dimensions between the active material layer 72 and the tab 713 arranged on both sides of the current collector 71 in the thickness direction are different, and the two isolation layers 51 are arranged on both sides of the empty foil portion 712. One end of the isolation layer 51 is connected to the empty foil portion 712, and the other end is connected to the active material layer 72. The isolation layers 51 arranged on both sides of the empty foil portion 712 have the same extension dimensions in the current collector 711.

[0143] In these embodiments, the minimum dimensions between the active material layer 72 and the tab 713 provided on both sides of the current collector 71 in the thickness direction are different, and two isolation layers 51 are provided on both sides of the hollow foil portion 712. One end of the isolation layer 51 is connected to the hollow foil portion 712, and the other end is connected to the active material layer 72. The isolation layers 51 provided on both sides of the hollow foil portion 712 have the same extension dimensions in the current collector 711. The isolation layer 51 can be used to balance the lengths of the active material layers 72 on both sides, so as to improve the problem of lithium deposition in the positive electrode sheet 7 due to the interlacing of the active material layers 72 on both sides.

[0144] During the coating process, due to process limitations, the active material layers 72 on both sides of the current collector 711 may be misaligned in the thickness direction. This results in part of the active material layer 72 in adjacent positive and negative electrode sheets 8 facing the current collector 71 of the other electrode sheet, preventing lithium ions from being embedded, thus causing lithium plating.

[0145] The minimum dimensions between the active material layer 72 and the tab 713 are different, meaning that the distances between the ends of the active material layers 72 near the tab 713 and the tab 713 on both sides of the thickness direction are different. The two active material layers 72 in the thickness direction of the current collector 71 are a first material layer and a second material layer. The end of the first material layer near the tab 713 overlaps with the end of the current collecting portion 711 near the tab 713, while the end of the second material layer near the tab 713 is located on the side of the current collecting portion 711 near the tab 713 facing away from the tab 713.

[0146] The two isolation layers 51 in the thickness direction of the current collector 71 are the first isolation layer and the second isolation layer. One end of the isolation layer 51 is set on the empty foil portion 712, and the other end extends toward the active material layer 72. The first isolation layer extends to the side of the first material layer away from the current collector 71, and the second isolation layer extends to the side of the second material layer away from the current collector 71, so as to improve the connection reliability between the active material layer 72 and the isolation layer 51, or the second isolation layer and the second material layer are abutted against each other along the arrangement direction of the current collector portion 711 and the empty foil portion 712 to reduce the size of the isolation layer 51 and save the cost of the battery cell 3.

[0147] The isolation layers 51 arranged on both sides of the empty foil portion 712 have the same extension direction in the current collecting portion 711. In this way, the isolation layer 51 is used to compensate for the overlap between the first material layer and the second material layer, so that the portions of the first material layer and the second material layer exposed from the isolation layer 51 are flush at the end facing the electrode ear 713, thereby improving the problem of lithium plating caused by the active material layer 72 and the current collector 71 of the adjacent electrode being directly opposite.

[0148] The extension size of the isolation layer 51 on the active material layer 72 can be designed independently. For example, the extension size of the isolation layer 51 on the active material layer 72 is 0.2 mm, 0.5 mm, or 0.7 mm.

[0149] In some embodiments, as Figure 9 and Figure 11 As shown, both separation layers 51 extend to the side of the active material layer 72 facing away from the current collector 71 .

[0150] In these embodiments, both isolation layers 51 extend to the side of the active material layer 72 facing away from the current collector 71 , which can improve the connection reliability between the isolation layer 51 and the active material layer 72 and reduce the difficulty of setting the isolation layer 51 .

[0151] Optionally, one end of the isolation layer 51 covers the entire surface of the hollow foil portion 712 in the thickness direction, and the other end of the isolation layer 51 extends to a side of the active material layer 72 away from the current collector 71 .

[0152] Optionally, the isolation layer 51 is bonded to a portion of the active material layer 72 to improve the stability of the isolation layer 51 .

[0153] In some embodiments, as Figure 9 and Figure 11 As shown, along the thickness direction of the positive electrode sheet 7 , the maximum dimension from the isolation layer 51 to the current collector 71 is smaller than the maximum dimension from the active material layer 72 to the current collector 71 .

[0154] In these embodiments, along the thickness direction of the positive electrode sheet 7, the maximum dimension from the isolation layer 51 to the current collector 71 is smaller than the maximum dimension from the active material layer 72 to the current collector 71, so as to improve the problem of bulging of the electrode assembly 5 caused by the isolation layer 51 being set too high.

[0155] Specifically, the active material layer 72 includes a base segment 721 and a thinned segment 722 connected to each other. The thinned segment 722 is located at one end of the base segment 721 facing the electrode ear 713. The size of the thinned segment 722 is smaller than that of the base segment 721. The isolation layer 51 extends to part of the thinned segment 722.

[0156] Along the thickness direction of the positive electrode sheet 7, the maximum dimension L1 from the active material layer 72 to the current collector 71 refers to the distance between the surface of the collective segment facing away from the current collector 71 and the current collector 71; along the thickness direction of the positive electrode sheet 7, the maximum dimension L2 from the isolation layer 51 to the current collector 71 refers to the distance between the surface of the isolation layer 51 facing away from the thinned section 722 and the current collector 71 after the isolation layer 51 covers part of the thinned section 722.

[0157] Second, as Figures 4 to 7 An embodiment of the present application provides a positive electrode sheet 7, which is applied to the battery cell 3 of the first embodiment mentioned above. The positive electrode sheet 7 includes a current collector 71 and an active material layer 72. The current collector 71 includes a current collecting portion 711, a hollow foil portion 712 and a pole tab 713 that are interconnected. The active material layer 72 is arranged on the current collecting portion 711, and the hollow foil portion 712 is arranged between the current collecting portion 711 and the pole tab 713. The electrode assembly 5 also includes an isolation layer 51, which covers at least part of the hollow foil portion 712.

[0158] In the solution of the embodiment of the present application, the positive electrode sheet 7 includes a current collector 71 and an active material layer 72. The current collector 71 includes a current collecting portion 711, a hollow foil portion 712 and a pole ear 713 that are interconnected. The active material layer 72 is arranged on the current collecting portion 711, and the hollow foil portion 712 is arranged between the current collecting portion 711 and the pole ear 713. The electrode assembly 5 also includes an isolation layer 51. By covering the isolation layer 51 on at least part of the hollow foil portion 712, the isolation layer 51 can block the burrs located on the hollow foil portion 712, thereby improving the problem that the burrs on the hollow foil portion 712 pierce the isolation piece 9 and cause the adjacent positive and negative electrode sheets 8 to short-circuit, thereby improving the reliability of the battery cell 3.

[0159] In some embodiments, as Figure 6and Figure 7 As shown, the isolation layer 51 is provided on at least one side of the hollow foil portion 712 in the thickness direction.

[0160] In these embodiments, the isolation layer 51 is arranged on at least one side of the hollow foil portion 712 in the thickness direction, so that the isolation layer 51 can block the burrs covering the hollow foil portion 712 in the thickness direction, thereby reducing the risk of the burrs in the thickness direction of the hollow foil portion 712 piercing the isolation member 9 and causing a short circuit in the battery cell 3.

[0161] In some embodiments, as Figure 6 and Figure 7 As shown, the hollow foil portion 712 includes end surfaces 7121 on both sides in the thickness direction thereof and side surfaces 7122 connected to the two end surfaces 7121 , and the isolation layer 51 is provided on part of the side surfaces 7122 .

[0162] In these embodiments, the hollow foil portion 712 includes end faces 7121 on both sides thereof in the thickness direction and side faces 7122 connected to the two end faces 7121. The isolation layer 51 is arranged on part of the side faces 7122 so that the isolation layer 51 can block the burrs covering the side faces 7122 of the hollow foil portion 712, thereby reducing the risk of the burrs on the side faces 7122 piercing the isolation member 9 and causing a short circuit in the battery cell 3.

[0163] In some embodiments, as Figure 5 、 Figures 9 to 11 As shown, the minimum dimensions between the active material layer 72 and the tab 713 arranged on both sides of the current collector 71 in the thickness direction are different, and the two isolation layers 51 are arranged on both sides of the empty foil portion 712. One end of the isolation layer 51 is connected to the empty foil portion 712, and the other end is connected to the active material layer 72. The isolation layers 51 arranged on both sides of the empty foil portion 712 have the same extension dimensions in the current collector 711.

[0164] In these embodiments, the minimum dimensions between the active material layer 72 and the tab 713 provided on both sides of the current collector 71 in the thickness direction are different, and two isolation layers 51 are provided on both sides of the hollow foil portion 712. One end of the isolation layer 51 is connected to the hollow foil portion 712, and the other end is connected to the active material layer 72. The isolation layers 51 provided on both sides of the hollow foil portion 712 have the same extension dimensions in the current collector 711. The isolation layer 51 can be used to balance the lengths of the active material layers 72 on both sides, so as to improve the problem of lithium deposition in the positive electrode sheet 7 due to the interlacing of the active material layers 72 on both sides.

[0165] In a third aspect, an embodiment of the present application provides a battery device comprising the battery cell of the embodiment of the first aspect described above.

[0166] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising the battery device of the embodiment of the third aspect described above.

[0167] In some embodiments, as Figures 1 to 11 As shown, the battery cell 3 includes a shell 4 and an electrode assembly 5, the electrode assembly 5 is arranged in the shell 4, the electrode assembly 5 includes a positive electrode sheet 7, the positive electrode sheet 7 includes a current collector 71 and an active material layer 72, the current collector 71 includes a current collector portion 711, a hollow foil portion 712 and a pole ear 713 connected to each other, the active material layer 72 is arranged on the current collector portion 711, and the hollow foil portion 712 is arranged between the current collector portion 711 and the pole ear 713, wherein the electrode assembly 5 also includes an isolation layer 51, the isolation layer 51 is an insulating material, the isolation layer 51 includes a first end 511 and a second end 512 arranged oppositely, the first end 511 is arranged on the surface of the hollow foil portion 712 in the thickness direction, and the second end 512 extends out of the hollow foil portion 712 in a direction away from the current collector portion 711 12. Two isolation layers 51 are arranged on both sides of the positive electrode sheet 7. The second ends 512 of the two isolation layers 51 are connected to each other. The minimum dimensions between the active material layer 72 and the electrode tab 713 on both sides of the current collector 71 in the thickness direction are different. The two isolation layers 51 are arranged on both sides of the empty foil portion 712. One end of the isolation layer 51 is connected to the empty foil portion 712, and the other end is connected to the active material layer 72. The isolation layers 51 on both sides of the empty foil portion 712 have the same extension dimensions on the current collector 711. Both isolation layers 51 extend to the side of the active material layer 72 away from the current collector 71. Along the thickness direction of the positive electrode sheet 7, the maximum dimension from the isolation layer 51 to the current collector 71 is smaller than the maximum dimension from the active material layer 72 to the current collector 71.

[0168] In the solution of the embodiment of the present application, the battery cell 3 includes a shell 4 and an electrode assembly 5, the electrode assembly 5 is accommodated in the shell 4, the electrode assembly 5 includes a positive electrode sheet 7, the positive electrode sheet 7 includes a current collector 71 and an active material layer 72, the current collector 71 includes a current collector portion 711, a hollow foil portion 712 and a pole ear 713 connected to each other, the active material layer 72 is arranged in the current collector portion 711, and the hollow foil portion 712 is arranged between the current collector portion 711 and the pole ear 713, and the electrode assembly 5 also includes an isolation layer 51. By covering the isolation layer 51 on at least part of the hollow foil portion 712, the isolation layer 51 can block the burrs located on the hollow foil portion 712, so as to improve the problem that the burrs of the hollow foil portion 712 pierce the isolation member 9 and cause the adjacent positive and negative electrode sheets 8 to contact and short-circuit, thereby improving the reliability of the battery cell 3.

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: case; The electrode assembly is arranged in the shell, the electrode assembly includes a positive electrode sheet, the positive electrode sheet includes a current collector and an active material layer, the current collector includes a current collector, a hollow foil portion and a tab connected to each other, the active material layer is arranged on the current collector, and the hollow foil portion is arranged between the current collector and the tab. Wherein, the electrode assembly further includes an isolation layer, and the isolation layer covers at least a portion of the hollow foil portion.

2. The battery cell according to claim 1, wherein: The isolation layer is provided on at least one side of the hollow foil portion in a thickness direction.

3. The battery cell according to any one of claims 1 or 2, characterized in that: The hollow foil portion includes end surfaces on both sides in the thickness direction thereof and side surfaces connected to the two end surfaces, and the isolation layer is provided on a portion of the side surfaces.

4. The battery cell according to claim 3, characterized in that The isolation layer includes a first end and a second end that are oppositely arranged, wherein the first end is arranged on the surface of the hollow foil portion in the thickness direction, and the second end extends out of the hollow foil portion in a direction away from the current collecting portion. The two isolation layers are respectively arranged on both sides of the positive electrode sheet, and the second ends of the two isolation layers are connected to each other.

5. The battery cell according to claim 4, characterized in that At least a portion of the second end extends to an end of the electrode tab close to the hollow foil portion.

6. The battery cell according to any one of claims 1 to 5, characterized in that: The minimum dimensions between the active material layer and the electrode tab arranged on both sides of the current collector in the thickness direction are different, and the two isolation layers are arranged on both sides of the empty foil portion. One end of the isolation layer is connected to the empty foil portion, and the other end is connected to the active material layer. The isolation layers arranged on both sides of the empty foil portion have the same extension dimensions on the current collector portion.

7. The battery cell according to claim 6, characterized in that The two isolation layers both extend to a side of the active material layer facing away from the current collector.

8. The battery cell according to claim 6, characterized in that Along the thickness direction of the positive electrode sheet, the maximum dimension from the isolation layer to the current collector is smaller than the maximum dimension from the active material layer to the current collector.

9. The battery cell according to any one of claims 1 to 8, characterized in that: The isolation layer is arranged at one end of the hollow foil portion away from the current collecting portion and extends toward the current collecting portion.

10. The battery cell according to any one of claims 1 to 9, characterized in that: The isolation layer is made of an insulating material so that the isolation layer and the current collector can be insulated from each other.

11. A positive electrode sheet, applied to the battery cell according to any one of claims 1 to 10, characterized in that: The positive electrode sheet includes a current collector and an active material layer. The current collector includes a current collector portion, a hollow foil portion, and a tab that are connected to each other. The active material layer is provided on the current collector portion, and the hollow foil portion is provided between the current collector portion and the tab. Wherein, the electrode assembly further includes an isolation layer, and the isolation layer covers at least a portion of the hollow foil portion.

12. The positive electrode sheet according to claim 11, characterized in that: The isolation layer is provided on at least one side of the hollow foil portion in a thickness direction.

13. The positive electrode sheet according to any one of claims 11 or 12, characterized in that: The hollow foil portion includes end surfaces on both sides in the thickness direction thereof and side surfaces connected to the two end surfaces, and the isolation layer is provided on a portion of the side surfaces.

14. The positive electrode sheet according to claim 11, characterized in that: The minimum dimensions between the active material layer and the electrode tab arranged on both sides of the current collector in the thickness direction are different, and the two isolation layers are arranged on both sides of the empty foil portion. One end of the isolation layer is connected to the empty foil portion, and the other end is connected to the active material layer. The isolation layers arranged on both sides of the empty foil portion have the same extension dimensions on the current collector portion.

15. A battery device, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 10.

16. An electrical device, characterized in that: A battery device comprising the battery device described in claim 15.

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