Battery cell and electric device

Abstract

Provided in the present application are a battery cell and an electric device. The battery cell comprises an electrode assembly. The electrode assembly comprises a plurality of first electrode sheets and a plurality of second electrode sheets that are stacked in a first direction, and separators. Each first electrode sheet comprises a first current collector and a first active material layer, the first current collector comprising a first coated area and a first blank foil area, the first blank foil area extending beyond the separators in a second direction; and the first blank foil areas of the plurality of first electrode sheets are stacked in the first direction and gathered together. Each separator is provided with an edge portion extending beyond the first coated areas in the second direction, the edge portion being provided with a notch; and the notches are located on the side of the first blank foil areas close to the first coated areas in a third direction. The overlap part between the edge portion of each separator and a first blank foil area can bend along with gathering of the first blank foil areas, while other parts of the edge portion of each separator do not easily deform, thereby reducing the likelihood of short circuits caused by contact between the first electrode sheets and the second electrode sheets, thus reducing the risk of thermal runaway in the battery cell, improving the safety of the battery cell.

Description

Battery cells and electrical equipment CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Chinese patent application CN202410383564.1, entitled “Battery Cells and Electrical Equipment,” filed on March 31, 2024, 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 and an electrical device. Background Art

[0003] With the rapid development of electronic information technology, various electronic devices are also developing towards intelligence and multi-functions, and the safety requirements for batteries are becoming increasingly higher.

[0004] Currently, electrode assemblies generally include positive and negative electrodes, with a separator placed between them to insulate the positive and negative electrodes. However, in a battery cell with a laminated structure, when multiple positive or negative tabs converge along the stacking direction of the positive and negative electrodes, they act on the separator, causing the separator's edges to bend and deform. This can cause a short circuit between the positive and negative electrodes, leading to thermal runaway and other problems in the battery cell, affecting the safety of the battery cell. Summary of the Invention

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

[0006] In a first aspect, an embodiment of the present application provides a battery cell, comprising an electrode assembly, the electrode assembly being a laminated structure, the electrode assembly comprising a plurality of first electrode sheets and a plurality of second electrode sheets, the plurality of first electrode sheets and the plurality of second electrode sheets being stacked along a first direction, the first electrode sheet and the second electrode sheet having opposite polarity; the first electrode sheet comprising a first current collector and a first active material layer, the first current collector comprising a first coating area and a first empty foil area, the first active material layer being arranged on the surface of the first coating area, and the first active material layer being not arranged on the surface of the first empty foil area; the electrode assembly further comprising a diaphragm, the diaphragm being arranged between the first electrode sheet and the second electrode sheet, the first empty foil area extending beyond the diaphragm along the second direction, the first empty foil areas of the plurality of first electrode sheets being stacked and gathered along the first direction; wherein the diaphragm has an edge portion extending beyond the first coating area along the second direction, the edge portion being provided with a cutout, the cutout being located on a side of the first empty foil area close to the first coating area in the third direction, and the first direction, the second direction and the third direction being perpendicular to each other.

[0007] In the above technical solution, the diaphragm is arranged between the first electrode and the second electrode, and can play an insulating role between the first electrode and the second electrode; the first empty foil area extends beyond the diaphragm in the second direction, and the first empty foil areas of multiple first electrode sheets are stacked and folded along the first direction, which can facilitate the first empty foil area to lead out of the battery cell to achieve electrical connection between the battery cell and the load; by arranging an incision on the edge of the diaphragm, the incision is located on the side of the first empty foil area close to the first coating area in the third direction, so that when the first empty foil areas of multiple first electrode sheets are folded, the part of the edge of the diaphragm overlapping with the first empty foil area is bent as the first empty foil area is folded, while the other parts of the edge of the diaphragm are not easily deformed, so as to be maintained between the first electrode sheet and the second electrode sheet, thereby reducing the possibility of short circuit between the first electrode sheet and the second electrode sheet, thereby reducing the risk of thermal runaway of the battery cell and improving the safety of the battery cell.

[0008] In some embodiments of the present application, along the first direction, the projection of the diaphragm and the projection of the first empty foil area have an overlapping area, along the second direction, the length of the overlapping area is L1, the length of the cut is L2, and L2≤L1 is satisfied.

[0009] In the above technical solution, by ensuring that the length L1 of the overlapping area and the length L2 of the incision along the second direction satisfy L2≤L1, the incision does not exceed the edge of the diaphragm, and the diaphragm can cover the first coating area, thereby reducing the possibility of short circuit between the first electrode and the second electrode, thereby reducing the risk of thermal runaway of the battery cell and improving the safety of the battery cell.

[0010] In some embodiments of the present application, along the first direction, edges of the two diaphragms located on both sides of the first pole piece are connected to each other.

[0011] In the above technical solution, by connecting the edges of the two layers of diaphragms on both sides of the first electrode sheet along the first direction to each other, the possibility of contact between the first electrode sheet and the second electrode sheet or the battery cell shell can be reduced, thereby reducing the possibility of short circuit between the first electrode sheet and the second electrode sheet, thereby reducing the risk of thermal runaway of the battery cell and improving the safety of the battery cell.

[0012] In some embodiments of the present application, along the third direction, a space is provided between the first empty foil area and the first coated area, and along the first direction, a projection of the cutout falls into the space.

[0013] In the above technical solution, along the third direction, the first empty foil area and the first coated area have a spacing space, which can prevent the first coated area from being deformed along with the first empty foil area when multiple first empty foil areas are folded together; along the first direction, the projection of the incision falls into the spacing space, which can separate the part of the edge of the diaphragm overlapping with the first empty foil area and the part overlapping with the first coated area, so that the part of the edge of the diaphragm overlapping with the first empty foil area is bent as the first empty foil area is folded, while the part of the edge of the diaphragm overlapping with the first coated area is not easily deformed, which can reduce the possibility of short circuit between the first electrode and the second electrode, thereby reducing the risk of thermal runaway of the battery cell and improving the safety of the battery cell.

[0014] In some embodiments of the present application, the first coating area has a first edge at one end in the second direction and a second edge at one end in the third direction. The first coating area also has a third edge and a fourth edge connected to each other, the third edge is connected to the first edge, and the fourth edge is connected to the second edge; the edge of the first coating area that intersects with the first empty foil area along the second direction is the fourth edge, and along the third direction, a spacing space is formed between the first empty foil area and the third edge, the third edge is inclined relative to the second direction, and the width of the spacing space in the third direction gradually increases along the direction away from the fourth edge.

[0015] In the above technical solution, by making the third edge inclined relative to the second direction, the width of the spacing space in the third direction gradually increases along the direction away from the fourth edge, which can reduce the possibility of multiple first empty foil areas contacting and short-circuiting with the second electrode during the process of shrinking and deformation, thereby reducing the risk of thermal runaway of the battery cell and improving the safety of the battery cell.

[0016] In some embodiments of the present application, the second pole piece has a first notch at a first corner, and when viewed along the first direction, the first empty foil area at least partially overlaps with the first notch.

[0017] In the above technical solution, by making the first empty foil area and the first notch at least partially overlap when viewed along the first direction, the volume of the first empty foil area protruding from the first coated area can be reduced, and the spacing space reserved between the electrode assembly and the battery cell shell for accommodating the first empty foil area is reduced, which can improve the energy density of the battery cell. When the battery cell is subjected to external force or falls, the electrode assembly is less likely to shake relative to the battery cell shell, and the possibility of the first empty foil area contacting and short-circuiting with the second electrode piece is also smaller, thereby reducing the risk of thermal runaway of the battery cell and improving the safety of the battery cell.

[0018] In some embodiments of the present application, the second corner of the first pole piece has a second notch, and when viewed along the first direction, the first notch and the second notch do not overlap; the second pole piece includes a second empty foil area, and when viewed along the first direction, the second empty foil area at least partially overlaps with the second notch, and the second empty foil areas of multiple second pole pieces are stacked and gathered along the first direction.

[0019] In the above technical solution, when viewed along the first direction, the first notch and the second notch do not overlap, and the second empty foil area at least partially overlaps with the second notch, which can reduce the possibility of short circuit caused by contact between the first empty foil area and the second empty foil area; the second empty foil areas of the multiple second pole pieces are stacked and gathered along the first direction, which can facilitate the second empty foil areas to lead out of the battery cell to achieve electrical connection between the battery cell and the load.

[0020] In some embodiments of the present application, the diaphragm has a third notch and a fourth notch. When viewed along the first direction, the first empty foil area at least partially overlaps with the third notch, and the second empty foil area at least partially overlaps with the fourth notch.

[0021] In the above technical solution, the diaphragm has a third notch and a fourth notch. When viewed along the first direction, the first empty foil area at least partially overlaps with the third notch, and the second empty foil area at least partially overlaps with the fourth notch, so that the third notch can be used to accommodate the first empty foil area, and the fourth notch can be used to accommodate the second empty foil area, which can facilitate the connection of multiple first empty foil areas and multiple second empty foil areas.

[0022] In some embodiments of the present application, an insulating layer is provided on the first empty foil area, and the insulating layer is connected to the first active material layer.

[0023] In the above technical solution, an insulating layer is provided on the first hollow foil area so that the insulating layer is connected to the first active material layer, thereby playing an insulating role between the first hollow foil area and the second electrode piece, reducing the possibility of the burrs on the end surface of the second electrode piece extending beyond the first coating area contacting and short-circuiting with the first hollow foil area, and the insulating layer can reduce the possibility of the first hollow foil area contacting and short-circuiting with the second electrode piece after being folded, thereby reducing the possibility of thermal runaway of the battery cell and improving the safety of the battery cell.

[0024] In some embodiments of the present application, along the second direction, the insulating layer exceeds the edge of the diaphragm.

[0025] In the above technical solution, by making the insulating layer extend beyond the edge of the diaphragm along the second direction, the possibility of the burrs on the end face of the second electrode extending beyond the first coating area contacting and short-circuiting with the first empty foil area can be further reduced, and the insulating layer can reduce the possibility of the first empty foil area contacting and short-circuiting with the second electrode after being folded, thereby reducing the possibility of thermal runaway of the battery cell and improving the safety of the battery cell.

[0026] In some embodiments of the present application, along the first direction, the projection of the diaphragm and the projection of the first empty foil area have an overlapping area, along the second direction, the length of the overlapping area is L1, and the length of the insulating layer is L3, satisfying L3>L1.

[0027] In the above technical solution, by making the length L1 of the overlapping area and the length L3 of the insulating layer satisfy L3>L1 along the second direction, the possibility of the burrs on the end surface of the second electrode extending beyond the first coating area contacting and short-circuiting with the first empty foil area can be further reduced, and the insulating layer can reduce the possibility of the first empty foil area contacting and short-circuiting with the second electrode after being folded, thereby reducing the possibility of thermal runaway of the battery cell and improving the safety of the battery cell.

[0028] In some embodiments of the present application, the thickness of the insulating layer is H1, and the thickness of the first active material layer is H2, satisfying H1≤H2.

[0029] In the above technical solution, by making the thickness H1 of the insulating layer and the thickness H2 of the first active material layer satisfy H1≤H2, the insulating layer can be made not to exceed the first active material layer in the thickness direction, so that the provision of the insulating layer will not increase the thickness of the electrode assembly, which is beneficial to improving the energy density of the battery cell.

[0030] In some embodiments of the present application, the thickness of the insulating layer is H, satisfying 0.005 mm ≤ H ≤ 0.1 mm.

[0031] In the above technical solution, when the thickness H of the insulating layer is greater than or equal to 0.005 mm, the thickness of the insulating layer can be larger, the insulation effect between the first empty foil area and the second electrode piece is better, the insulation reliability is higher, the possibility of short circuit between the first empty foil area and the second electrode piece is reduced, and the possibility of thermal runaway of the battery cell can be reduced; when the thickness H of the insulating layer is less than or equal to 0.1 mm, the insulating layer can not exceed the first active material layer in the thickness direction, so that the provision of the insulating glue layer will not increase the thickness of the electrode assembly, which is beneficial to improving the energy density of the battery cell; therefore, when the thickness H of the insulating layer is 0.005 mm-0.1 mm, the insulating layer can have a better insulation effect between the first empty foil area and the second electrode piece, the insulation reliability is higher, the possibility of short circuit between the first empty foil area and the second electrode piece is reduced, and the possibility of thermal runaway of the battery cell can be reduced; the insulating layer can not exceed the first active material layer in the thickness direction, so that the provision of the insulating layer will not increase the thickness of the electrode assembly, which is beneficial to improving the energy density of the battery cell.

[0032] In some embodiments of the present application, 0.01 mm ≤ H ≤ 0.05 mm.

[0033] In the above technical solution, when the thickness H of the insulating layer is greater than or equal to 0.01 mm, the thickness of the insulating layer can be further increased, the insulation effect between the first empty foil area and the second electrode piece is better, the insulation reliability is higher, the possibility of short circuit between the first empty foil area and the second electrode piece is reduced, and the possibility of thermal runaway of the battery cell can be reduced; when the thickness H of the insulating layer is less than or equal to 0.05 mm, the insulating layer can be further made not to exceed the first active material layer in the thickness direction, so that the provision of the insulating glue layer will not increase the thickness of the electrode assembly, which is beneficial to improving the energy density of the battery cell; therefore, when the thickness H of the insulating layer is 0.01 mm-0.05 mm, it can not only further make the insulation effect between the first empty foil area and the second electrode piece better, the insulation reliability is higher, the possibility of short circuit between the first empty foil area and the second electrode piece is reduced, and the possibility of thermal runaway of the battery cell can be reduced; it can also further make the insulating layer not exceed the first active material layer in the thickness direction, so that the provision of the insulating layer will not increase the thickness of the electrode assembly, which is beneficial to improving the energy density of the battery cell.

[0034] In some embodiments of the present application, the insulating layer includes a polymer material and an auxiliary material, the polymer material includes at least one of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylate, styrene, acrylonitrile, polyamide, maleic anhydride, vinyl chloride and allyl chloride, and the auxiliary material includes carboxymethyl cellulose and polyoxyethylene ether.

[0035] In the above technical solution, the insulating layer includes polymer materials and auxiliary materials, the polymer materials include at least one of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylate, styrene, acrylonitrile, polyamide, maleic anhydride, vinyl chloride and allyl chloride, and the auxiliary materials include carboxymethyl cellulose and polyoxyethylene ether, which can make the hardness of the insulating layer lower and not easily damage the first empty foil area when the first empty foil area is folded; enable the insulating layer to be bonded to the diaphragm, reduce the possibility of the edge of the diaphragm warping when subjected to external force or falling, thereby reducing the possibility of short circuit between the first electrode and the second electrode, reducing the possibility of thermal runaway of the battery cell, and improving the safety of the battery cell; and can make the preparation difficulty and cost of the insulating layer lower, the insulating layer can be attached to the first empty foil area along different shapes, and has a wider range of use.

[0036] In some embodiments of the present application, the first electrode is a positive electrode, and the second electrode is a negative electrode.

[0037] In a second aspect, an embodiment of the present application provides an electrical device, comprising a battery cell as described above, the battery cell being used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 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 of the present application. 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.

[0039] FIG1 is a schematic diagram of the three-dimensional structure of a battery cell provided in some embodiments of the present application;

[0040] FIG2 is a schematic diagram of the three-dimensional structure of an electrode assembly of a battery cell provided in some embodiments of the present application;

[0041] FIG3 is a schematic diagram of an exploded structure of an electrode assembly of a battery cell provided in some embodiments of the present application;

[0042] FIG4 is a schematic structural diagram of a first electrode piece of a battery cell provided in some embodiments of the present application;

[0043] FIG5 is a schematic structural diagram of a first current collector of a battery cell provided in some embodiments of the present application;

[0044] FIG6 is a schematic diagram of a partial structure of a battery cell provided in some embodiments of the present application;

[0045] FIG7 is a schematic diagram of a partial enlarged structure of the battery cell at point A in FIG6 ;

[0046] FIG8 is a schematic cross-sectional view of a partial structure of a battery cell provided in some embodiments of the present application;

[0047] FIG9 is a schematic structural diagram of a second pole piece of a battery cell provided in some embodiments of the present application;

[0048] FIG10 is a schematic structural diagram of a second current collector of a battery cell provided in some embodiments of the present application;

[0049] FIG11 is a schematic diagram of the structure of a diaphragm of a battery cell provided in some embodiments of the present application;

[0050] FIG12 is a schematic diagram of a partial structure of a battery cell provided in some other embodiments of the present application;

[0051] FIG13 is a schematic diagram of a partially enlarged structure of a portion B of the battery cell in FIG12 .

[0052] Icons: 10-battery cell; 100-electrode assembly; 110-first pole piece; 110a-second notch; 111-first current collector; 1111-first coating area; 1111a-first edge; 1111b-second edge; 1111c-third edge; 1111d-fourth edge; 1112-first empty foil area; 112-first active material layer; 120-second pole piece; 120a-first notch; 121-second current collector; 1211-second coating area; 1212-second empty foil area; 122-second active material layer; 130-separator; 130a-third notch; 130b-fourth notch; 131-edge; 1311-cutout; 1312-second notch; 140-insulating layer; 150-second insulating layer; 200-battery cell housing; X-first direction; Y-second direction; Z-third direction.

[0053] To make the purpose, technical solutions, and advantages 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 are within the scope of protection of this application.

[0054] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0055] The terms "first", "second" and the like 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.

[0056] 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.

[0057] 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.

[0058] A battery generally includes a positive electrode sheet, a negative electrode sheet, and a diaphragm. The diaphragm is arranged between the positive electrode sheet and the negative electrode sheet to achieve insulation between the positive electrode sheet and the negative electrode sheet. With the development of the new energy industry, batteries are gradually developing in the direction of high energy density and high power density, and the structure inside the battery is also more compact. If the diaphragm is deformed, it may cause direct contact between the positive electrode sheet and the negative electrode sheet, and then cause a short circuit between the positive electrode sheet and the negative electrode sheet, and thermal runaway of the battery cell. In a battery with a stacked structure, multiple positive electrode tabs or multiple negative electrode tabs will be deformed when they are folded together, thereby acting on the diaphragm, causing the edge of the diaphragm to bend and deform, posing a safety hazard. The folding of the tabs means that multiple tabs are pressed into contact with each other in the thickness direction, so that they can be more conveniently welded together and connected to external electrical connectors.

[0059] In order to improve the safety of a battery cell, the present application provides a battery cell, which includes an electrode assembly, the electrode assembly is a laminated structure, the electrode assembly includes multiple first electrode sheets and multiple second electrode sheets, the multiple first electrode sheets and the multiple second electrode sheets are stacked along a first direction, and the polarity of the first electrode sheet is opposite to that of the second electrode sheet; the first electrode sheet includes a first current collector and a first active material layer, the first current collector includes a first coating area and a first empty foil area, the first active material layer is set on the surface of the first coating area, and the first active material layer is not set on the surface of the first empty foil area; the electrode assembly also includes a diaphragm, the diaphragm is arranged between the first electrode sheet and the second electrode sheet, the first empty foil area extends beyond the diaphragm along the second direction, and the first empty foil areas of the multiple first electrode sheets are stacked and gathered along the first direction; wherein the diaphragm has an edge portion extending beyond the first coating area along the second direction, and a cut is provided on the edge portion, and the cut is located on the side of the first empty foil area close to the first coating area in the third direction, and the first direction, the second direction and the third direction are perpendicular to each other.

[0060] In a battery cell of this structure, a diaphragm is arranged between the first electrode piece and the second electrode piece, and can play an insulating role between the first electrode piece and the second electrode piece; the first empty foil area extends beyond the diaphragm in the second direction, and the first empty foil areas of multiple first electrode pieces are stacked and gathered in the first direction, which can facilitate the first empty foil area to be led out of the battery cell to achieve electrical connection between the battery cell and the load; by arranging an incision on the edge of the diaphragm, the incision is located on the side of the first empty foil area close to the first coating area in the third direction, so that when the first empty foil areas of multiple first electrode pieces are gathered, the part of the edge of the diaphragm overlapping with the first empty foil area is bent as the first empty foil area is gathered, while the other parts of the edge of the diaphragm are not easily deformed, so as to be maintained between the first electrode piece and the second electrode piece, thereby reducing the possibility of short circuit between the first electrode piece and the second electrode piece, thereby reducing the risk of thermal runaway of the battery cell and improving the safety of the battery cell.

[0061] The battery cells provided in the embodiments of the present application may be secondary batteries or primary batteries, such as lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, and are not limited in this embodiment. The electrochemical devices may be cylindrical, flat, rectangular, or in other shapes, and are not limited in this embodiment.

[0062] The embodiments of the present application provide an electrical device that uses a battery cell as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, and the like.

[0063] Referring to Figures 1 to 7, Figure 1 is a schematic diagram of the three-dimensional structure of the battery cell provided in some embodiments of the present application; Figure 2 is a schematic diagram of the three-dimensional structure of the electrode assembly of the battery cell provided in some embodiments of the present application; Figure 3 is a schematic diagram of the exploded structure of the electrode assembly of the battery cell provided in some embodiments of the present application; Figure 4 is a schematic diagram of the structure of the first pole piece of the battery cell provided in some embodiments of the present application; Figure 5 is a schematic diagram of the structure of the first current collector of the battery cell provided in some embodiments of the present application; Figure 6 is a schematic diagram of the partial structure of the battery cell provided in some embodiments of the present application; and Figure 7 is a schematic diagram of the local enlarged structure of point A of the battery cell in Figure 6.

[0064] An embodiment of the present application provides a battery cell 10, which includes an electrode assembly 100. The electrode assembly 100 is a laminated structure, and the electrode assembly 100 includes a plurality of first pole pieces 110 and a plurality of second pole pieces 120. The plurality of first pole pieces 110 and the plurality of second pole pieces 120 are stacked along a first direction X, and the first pole pieces 110 and the second pole pieces 120 have opposite polarities.

[0065] In some embodiments, the first electrode 110 includes a first current collector 111 and a first active material layer 112. The first current collector 111 includes a first coating area 1111 and a first empty foil area 1112. The first active material layer 112 is set on the surface of the first coating area 1111, and the first active material layer 112 is not set on the surface of the first empty foil area 1112.

[0066] In some embodiments, the electrode assembly 100 further includes a diaphragm 130, which is disposed between the first electrode piece 110 and the second electrode piece 120, and the first empty foil area 1112 extends beyond the diaphragm 130 along the second direction Y. The first empty foil areas 1112 of the plurality of first electrode pieces 110 are stacked and gathered along the first direction X.

[0067] By disposing the diaphragm 130 between the first electrode piece 110 and the second electrode piece 120, insulation can be provided between the first electrode piece 110 and the second electrode piece 120. The first hollow foil area 1112 extends beyond the diaphragm 130 along the second direction Y. The first hollow foil areas 1112 of the plurality of first electrode pieces 110 are stacked and gathered along the first direction X, which facilitates the first hollow foil areas 1112 to be led out of the battery cell 10, thereby achieving electrical connection between the battery cell 10 and the load.

[0068] In some embodiments, the diaphragm 130 has an edge portion 131 extending beyond the first coating area 1111 along the second direction Y, and a cutout 1311 is provided on the edge portion 131. The cutout 1311 is located on a side of the first empty foil area 1112 close to the first coating area 1111 in the third direction Z. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0069] By providing a cutout 1311 on the edge portion 131 of the diaphragm 130, the cutout 1311 is located on the side of the first empty foil area 1112 in the third direction Z close to the first coating area 1111, so that when the first empty foil areas 1112 of the plurality of first pole pieces 110 are folded together, the overlapping portion of the edge portion 131 of the diaphragm 130 and the first empty foil area 1112 is bent as the first empty foil area 1112 is folded together, while other portions of the edge portion 131 of the diaphragm 130 are not easily deformed, so as to be maintained between the first pole piece 110 and the second pole piece 120, thereby reducing the possibility of short circuit between the first pole piece 110 and the second pole piece 120, thereby reducing the risk of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0070] In some embodiments, referring to FIG7 , along a first direction X, the projection of the diaphragm 130 and the projection of the first hollow foil region 1112 have an overlapping area. Along a second direction Y, the length of the overlapping area is L1, and the length of the cutout 1311 is L2, satisfying L2 ≤ L1. For example, L2 can be L1, 0.9*L1, or 0.8*L1, etc.

[0071] By ensuring that the length L1 of the overlapping area and the length L2 of the incision 1311 along the second direction Y satisfy L2≤L1, the incision 1311 does not exceed the edge 131 of the diaphragm 130, and the diaphragm 130 can cover the first coating area 1111, thereby reducing the possibility of short circuit between the first electrode 110 and the second electrode 120, thereby reducing the risk of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0072] Refer to FIG8 , which is a schematic cross-sectional view of a partial structure of a battery cell provided in some embodiments of the present application.

[0073] In some embodiments, along the first direction X, the edge portions 131 of the two diaphragms 130 located on both sides of the first pole piece 110 are connected to each other.

[0074] By interconnecting the edge portions 131 of the two layers of diaphragms 130 located on both sides of the first electrode sheet 110 along the first direction X, the possibility of contact between the first electrode sheet 110 and the second electrode sheet 120 or the battery cell housing 200 can be reduced, thereby reducing the possibility of a short circuit between the first electrode sheet 110 and the second electrode sheet 120, thereby reducing the risk of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0075] In some embodiments, the first electrode 110 is a positive electrode, and the second electrode 120 is a negative electrode.

[0076] In a hard-shell battery cell, the negative electrode plate can be electrically connected to the load through the battery cell shell 200, and the second electrode plate 120 can be electrically connected to the battery cell shell 200. By interconnecting the edge portions 131 of the two layers of diaphragm 130 located on both sides of the first electrode plate 110 along the first direction X, the possibility of a short circuit caused by contact between the positive electrode plate and the battery cell shell 200 can be reduced, thereby reducing the risk of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0077] In some other embodiments, along the first direction X, the edge portions 131 of the two diaphragms 130 located on both sides of the second pole piece 120 are connected to each other.

[0078] By connecting the edge portions 131 of the two layers of diaphragm 130 located on both sides of the second electrode sheet 120 along the first direction X, the possibility of contact between the first electrode sheet 110 and the second electrode sheet 120 or the battery cell housing 200 can be reduced, thereby reducing the possibility of short circuit between the first electrode sheet 110 and the second electrode sheet 120, thereby reducing the risk of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0079] Since in the soft-pack battery cell, the potential difference between the negative electrode sheet and the battery cell shell 200 is greater than the potential difference between the positive electrode sheet and the battery cell shell 200, if the negative electrode sheet contacts the battery cell shell 200, the possibility of corrosion of the battery cell shell 200 is relatively high. By connecting the edge portions 131 of the two layers of diaphragm 130 located on both sides of the second electrode sheet 120 along the first direction X to each other, the possibility of corrosion of the battery cell shell 200 due to contact between the negative electrode sheet and the battery cell shell 200 can be reduced, which is beneficial to extending the service life of the battery cell 10.

[0080] In some embodiments, along the third direction Z, a space is separated between the first empty foil area 1112 and the first coated area 1111 , and along the first direction X, a projection of the cutout 1311 falls into the space.

[0081] By providing a space between the first hollow foil area 1112 and the first coated area 1111 along the third direction Z, the first coated area 1111 is less likely to deform with the first hollow foil areas 1112 when the plurality of first hollow foil areas 1112 are collapsed. Along the first direction X, the projection of the cutout 1311 falls into the space, separating the portion of the edge 131 of the diaphragm 130 that overlaps with the first hollow foil areas 1112 from the portion that overlaps with the first coated area 1111. This allows the portion of the edge 131 of the diaphragm 130 that overlaps with the first hollow foil areas 1112 to bend as the first hollow foil areas 1112 collapse, while the portion of the edge 131 of the diaphragm 130 that overlaps with the first coated area 1111 is less likely to deform. This reduces the possibility of short circuiting between the first electrode sheet 110 and the second electrode sheet 120, thereby reducing the risk of thermal runaway in the battery cell 10 and improving the safety of the battery cell 10.

[0082] In some embodiments, referring to Figure 4, the first coating area 1111 has a first edge 1111a at one end in the second direction Y and a second edge 1111b at one end in the third direction Z. The first coating area 1111 also has a connected third edge 1111c and a fourth edge 1111d, the third edge 1111c is connected to the first edge 1111a, and the fourth edge 1111d is connected to the second edge 1111b.

[0083] The edge where the first coated area 1111 meets the first hollow foil area 1112 along the second direction Y is a fourth edge 1111d. A space is formed between the first hollow foil area 1112 and the third edge 1111c along the third direction Z. The third edge 1111c is inclined relative to the second direction Y. The width of the space gradually increases in the direction away from the fourth edge 1111d in the third direction Z. The third edge 1111c can be inclined in a straight line, a wavy shape, or a curved shape.

[0084] By making the third edge 1111c inclined relative to the second direction Y, the width of the spacing space in the third direction Z gradually increases along the direction away from the fourth edge 1111d, which can reduce the possibility of the multiple first empty foil areas 1112 contacting and short-circuiting with the second electrode 120 during the process of shrinking and deforming, thereby reducing the risk of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0085] In some embodiments, the second electrode 120 has a first notch 120 a at a first corner thereof. When viewed along the first direction X, the first empty foil region 1112 at least partially overlaps with the first notch 120 a.

[0086] The corner position in this application refers to the position at the top corner of the pole piece. For example, the first empty foil area 1112 is located at the first pole piece 110, that is, two edges and one corner of the first empty foil area 1112 coincide with two edges and one corner of the first pole piece 110.

[0087] In some embodiments, the first angular position of the second pole piece 120 is a position at a top corner of the second pole piece 120 .

[0088] By ensuring that the first empty foil area 1112 and the first notch 120a at least partially overlap when viewed along the first direction X, the volume of the first empty foil area 1112 protruding from the first coated area 1111 can be reduced, and the spacing space reserved between the electrode assembly 100 and the battery cell shell 200 for accommodating the first empty foil area 1112 is reduced, which can improve the energy density of the battery cell 10. When the battery cell 10 is subjected to external force or falls, the electrode assembly 100 is less likely to shake relative to the battery cell shell 200, and the possibility of the first empty foil area 1112 contacting and short-circuiting with the second electrode sheet 120 is also less, thereby reducing the risk of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0089] In other embodiments, along the third direction Z, the first empty foil area 1112 can be arranged in the middle of the first electrode 110, and the first empty foil area 1112 is provided with cutouts 1311 on both sides of the third direction Z, so that when the first empty foil areas 1112 of multiple first electrode sheets 110 are folded, the edge portion 131 of the diaphragm 130 and the overlapping portion of the first empty foil area 1112 are bent as the first empty foil area 1112 are folded, while other portions of the edge portion 131 of the diaphragm 130 are not easily deformed, so as to be maintained between the first electrode sheet 110 and the second electrode sheet 120, thereby reducing the possibility of short circuit between the first electrode sheet 110 and the second electrode sheet 120, thereby reducing the risk of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0090] 4 , 9 and 10 , FIG9 is a schematic structural diagram of the second electrode of the battery cell provided in some embodiments of the present application; FIG10 is a schematic structural diagram of the second current collector of the battery cell provided in some embodiments of the present application.

[0091] In some embodiments, the second electrode 120 includes a second current collector 121 and a second active material layer 122. The second current collector 121 includes a second coating area 1211 and a second empty foil area 1212. The second active material layer 122 is set on the surface of the second coating area 1211, and the second active material layer 122 is not set on the surface of the second empty foil area 1212.

[0092] In some embodiments, the first pole piece 110 has a second notch 110 a at the second corner thereof. When viewed along the first direction X, the first notch 120 a and the second notch 110 a do not overlap.

[0093] In some embodiments, the second angular position of the first pole piece 110 is a position at a top corner of the first pole piece 110 .

[0094] When viewed along the first direction X, the second empty foil area 1212 at least partially overlaps with the second notch 110 a . The second empty foil areas 1212 of the plurality of second electrode sheets 120 are stacked and gathered along the first direction X.

[0095] By ensuring that the first notch 120a and the second notch 110a do not overlap and that the second hollow foil area 1212 at least partially overlaps the second notch 110a when viewed along the first direction X, the possibility of a short circuit caused by contact between the first hollow foil area 1112 and the second hollow foil area 1212 can be reduced. The second hollow foil areas 1212 of the plurality of second electrode sheets 120 are stacked and gathered along the first direction X, making it easier for the second hollow foil areas 1212 to be led out of the battery cell 10, thereby achieving electrical connection between the battery cell 10 and the load.

[0096] See 11 , which is a schematic structural diagram of a diaphragm of a battery cell provided in some embodiments of the present application.

[0097] In some embodiments, the diaphragm 130 has a third notch 130a and a fourth notch 130b. When viewed along the first direction X, the first empty foil area 1112 at least partially overlaps the third notch 130a, and the second empty foil area 1212 at least partially overlaps the fourth notch 130b.

[0098] By providing the diaphragm 130 with the third notch 130a and the fourth notch 130b, when viewed along the first direction X, the first empty foil area 1112 at least partially overlaps with the third notch 130a, and the second empty foil area 1212 at least partially overlaps with the fourth notch 130b, so that the third notch 130a can be used to accommodate the first empty foil area 1112, and the fourth notch 130b can be used to accommodate the second empty foil area 1212, which facilitates the connection of multiple first empty foil areas 1112 and multiple second empty foil areas 1212.

[0099] In some embodiments, along the third direction Z, a space is separated between the second empty foil area 1212 and the second coated area 1211 .

[0100] By providing a space between the second empty foil area 1212 and the second coated area 1211 along the third direction Z, the second coated area 1211 is less likely to be deformed along with the second empty foil area 1212 when the plurality of second empty foil areas 1212 are folded together.

[0101] In some embodiments, an insulating layer 140 is disposed on the first empty foil area 1112 , and the insulating layer 140 is connected to the first active material layer 112 .

[0102] By arranging the insulating layer 140 on the first empty foil area 1112, the insulating layer 140 is connected to the first active material layer 112, which can play an insulating role between the first empty foil area 1112 and the second electrode piece 120, reducing the possibility of the burrs on the end surface of the second electrode piece 120 extending beyond the first coating area 1111 and contacting and short-circuiting with the first empty foil area 1112. In addition, the insulating layer 140 can reduce the possibility of the first empty foil area 1112 contacting and short-circuiting with the second electrode piece 120 after being folded, thereby reducing the possibility of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0103] In some embodiments, along the second direction Y, the insulating layer 140 extends beyond the edge of the diaphragm 130 .

[0104] By allowing the insulating layer 140 to extend beyond the edge of the diaphragm 130 along the second direction Y, the possibility of the burrs on the end surface of the second electrode piece 120 extending beyond the first coating area 1111 and short-circuiting with the first empty foil area 1112 can be further reduced. In addition, the insulating layer 140 can reduce the possibility of the first empty foil area 1112 short-circuiting with the second electrode piece 120 after being folded, thereby reducing the possibility of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0105] In some embodiments, along the first direction X, the projection of the diaphragm 130 and the projection of the first hollow foil region 1112 have an overlapping area. Along the second direction Y, the length of the overlapping area is L1, and the length of the insulating layer 140 is L3, satisfying L3>L1. For example, L3 can be 1.1*L1, 1.3*L1, or 1.5*L1, etc.

[0106] By ensuring that the length L1 of the overlapping area and the length L3 of the insulating layer 140 satisfy L3>L1 along the second direction Y, the possibility of the burrs on the end surface of the second electrode piece 120 extending beyond the first coating area 1111 and short-circuiting with the first empty foil area 1112 can be further reduced, and the insulating layer 140 can reduce the possibility of the first empty foil area 1112 short-circuiting with the second electrode piece 120 after being folded, thereby reducing the possibility of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0107] In some embodiments, the thickness of the insulating layer 140 is H1, and the thickness of the first active material layer 112 is H2, satisfying H1≤H2. For example, H1 can be H2, 0.9*H2, or 0.8*H2.

[0108] By making the thickness H1 of the insulating layer 140 and the thickness H2 of the first active material layer 112 satisfy H1≤H2, the insulating layer 140 can be prevented from exceeding the first active material layer 112 in the thickness direction, so that the provision of the insulating layer 140 does not increase the thickness of the electrode assembly 100, which is beneficial to improving the energy density of the battery cell 10.

[0109] In some embodiments, the thickness of the insulating layer 140 is H, which satisfies 0.005 mm ≤ H ≤ 0.1 mm. For example, H can be 0.005 mm, 0.03 mm, or 0.1 mm.

[0110] When the thickness H of the insulating layer 140 is greater than or equal to 0.005 mm, the thickness of the insulating layer 140 can be larger, the insulation effect between the first empty foil area 1112 and the second electrode 120 is better, the insulation reliability is higher, and the possibility of short circuit between the first empty foil area 1112 and the second electrode 120 is reduced, thereby reducing the possibility of thermal runaway of the battery cell 10; when the thickness H of the insulating layer 140 is less than or equal to 0.1 mm, the insulating layer 140 does not exceed the first active material layer 112 in the thickness direction, so that the provision of the insulating glue layer does not increase the thickness of the electrode assembly 100, which is beneficial to improving The energy density of the battery cell 10; therefore, when the thickness H of the insulating layer 140 is 0.005mm-0.1mm, the insulating layer 140 can have a better insulation effect on the first empty foil area 1112 and the second electrode sheet 120, and the insulation reliability is higher, which can reduce the possibility of short circuit between the first empty foil area 1112 and the second electrode sheet 120, thereby reducing the possibility of thermal runaway of the battery cell 10; and the insulating layer 140 can not exceed the first active material layer 112 in the thickness direction, so that the setting of the insulating layer 140 will not increase the thickness of the electrode assembly 100, which is beneficial to improving the energy density of the battery cell 10.

[0111] In some embodiments, 0.01 mm ≤ H ≤ 0.05 mm. For example, H may be 0.01 mm, 0.02 mm, or 0.05 mm.

[0112] When the thickness H of the insulating layer 140 is greater than or equal to 0.01 mm, the thickness of the insulating layer 140 can be further increased, the insulation effect between the first empty foil area 1112 and the second electrode 120 is better, the insulation reliability is higher, and the possibility of short circuit between the first empty foil area 1112 and the second electrode 120 is reduced, thereby reducing the possibility of thermal runaway of the battery cell 10; when the thickness H of the insulating layer 140 is less than or equal to 0.05 mm, the insulating layer 140 can be further made not to exceed the first active material layer 112 in the thickness direction, so that the provision of the insulating glue layer will not increase the thickness of the electrode assembly 100, which is beneficial to improving The energy density of the battery cell 10; therefore, when the thickness H of the insulating layer 140 is 0.01mm-0.05mm, the insulating layer 140 can further improve the insulation effect between the first empty foil area 1112 and the second electrode 120, and the insulation reliability is higher, which can reduce the possibility of short circuit between the first empty foil area 1112 and the second electrode 120, thereby reducing the possibility of thermal runaway of the battery cell 10; and can further ensure that the insulating layer 140 does not exceed the first active material layer 112 in the thickness direction, so that the setting of the insulating layer 140 will not increase the thickness of the electrode assembly 100, which is beneficial to improving the energy density of the battery cell 10.

[0113] In some embodiments, the insulating layer 140 includes a polymer material and an auxiliary material, the polymer material includes at least one of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylate, styrene, acrylonitrile, polyamide, maleic anhydride, vinyl chloride and allyl chloride, and the auxiliary material includes carboxymethyl cellulose and polyoxyethylene ether.

[0114] By making the insulating layer 140 include a polymer material and auxiliary materials, the polymer material includes at least one of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylic ester, styrene, acrylonitrile, polyamide, maleic anhydride, vinyl chloride and allyl chloride, and the auxiliary materials include carboxymethyl cellulose and polyoxyethylene ether, the hardness of the insulating layer 140 can be made low, and the first empty foil area 1112 is not easily damaged when the first empty foil area 1112 is folded; the insulating layer 140 can be bonded to the diaphragm 130, reducing the possibility of the edge 131 of the diaphragm 130 warping when subjected to external force or falling, thereby reducing the possibility of short circuit between the first electrode 110 and the second electrode 120, reducing the possibility of thermal runaway of the battery cell 10, and improving the safety of the battery cell 10; and the preparation difficulty and cost of the insulating layer 140 are low, the insulating layer 140 can be attached to the first empty foil area 1112 along different shapes, and has a wide range of uses.

[0115] 12 and 13 , FIG12 is a schematic diagram of a partial structure of a battery cell provided in some other embodiments of the present application; FIG13 is a schematic diagram of a partially enlarged structure of point B of the battery cell in FIG12 .

[0116] In some other embodiments, a second cutout 1312 is provided on the edge portion 131 , and the second cutout 1312 is located on a side of the second empty foil area 1212 close to the second coating area 1211 in the third direction Z.

[0117] By setting a second incision 1312 on the edge portion 131 of the diaphragm 130, the second incision 1312 is located on the side of the second empty foil area 1212 close to the second coating area 1211 in the third direction Z. When the second empty foil areas 1212 of the plurality of second pole pieces 120 are folded, the overlapping portion of the edge portion 131 of the diaphragm 130 and the second empty foil area 1212 is folded and bent as the second empty foil area 1212 is folded, while other portions of the edge portion 131 of the diaphragm 130 are not easily deformed, so as to be maintained between the first pole piece 110 and the second pole piece 120, thereby reducing the possibility of short circuit between the first pole piece 110 and the second pole piece 120, thereby reducing the risk of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0118] In some embodiments, a second insulating layer 150 is disposed on the second empty foil area 1212 , and the second insulating layer 150 is connected to the second active material layer 122 .

[0119] By providing a second insulating layer 150 on the second empty foil area 1212, the second insulating layer 150 is connected to the second active material layer 122, which can play an insulating role between the second empty foil area 1212 and the first electrode sheet 110, thereby reducing the possibility of the second empty foil area 1212 contacting and short-circuiting with the first electrode sheet 110 after being folded, thereby reducing the possibility of thermal runaway of the battery cell 10 and improving the safety of the battery cell 10.

[0120] In some embodiments, the battery cell 10 further includes a battery cell housing, the battery cell housing is provided with an accommodation space, and the electrode assembly 100 is accommodated in the accommodation space.

[0121] In some embodiments, the cell housing 100 may be made of a relatively high-strength material, such as steel, aluminum alloy, or other metal material, so that the cell housing 100 has a relatively high acceptance performance, thereby making the cell housing 100 less likely to be deformed or damaged due to stress or environmental changes, thereby making the electrochemical device 10 more reliable.

[0122] In other embodiments, the battery cell casing 100 may also be made of non-metallic materials with relatively high strength, such as carbon fiber, hard plastic, etc.

[0123] The battery cell 10 includes an electrode assembly 100, a battery cell shell 200 and an electrolyte. The battery cell shell 200 is used to accommodate the electrode assembly 100 and the electrolyte. The electrode assembly 100 is composed of a positive electrode sheet, a negative electrode sheet and a separator. The battery cell 10 mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. 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 part of the positive electrode collector that is not coated with the positive electrode active material layer serves as the positive electrode tab to realize the input or output of electrical energy of the positive electrode sheet through the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary material or lithium manganese oxide, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The portion of the negative electrode current collector not coated with the negative electrode active material layer serves as the negative electrode tab, through which electrical energy is input or output from the negative electrode sheet. The negative electrode current collector can be made of copper, and the negative electrode active material can be made of carbon or silicon. The separator can be made of polypropylene (PP) or polyethylene (PE). The electrolyte can include organic solvents, electrolyte lithium salts, etc.

[0124] In a second aspect, an embodiment of the present application provides an electrical device, including the battery cell 10 as described above, and the battery cell 10 is used to provide electrical energy.

[0125] 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.

[0126] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, characterized in that: The electrode assembly comprises an electrode assembly having a laminated structure, comprising a plurality of first electrode sheets and a plurality of second electrode sheets, wherein the plurality of first electrode sheets and the plurality of second electrode sheets are stacked along a first direction, and the polarity of the first electrode sheets and the polarity of the second electrode sheets are opposite; The first electrode sheet includes a first current collector and a first active material layer. The first current collector includes a first coating area and a first hollow foil area. The first active material layer is disposed on a surface of the first coating area, and the first active material layer is not disposed on a surface of the first hollow foil area. The electrode assembly further includes a diaphragm, the diaphragm being disposed between the first electrode piece and the second electrode piece, the first hollow foil area extending beyond the diaphragm along a second direction, and the first hollow foil areas of a plurality of the first electrode pieces being stacked and gathered along the first direction; The diaphragm has an edge portion extending beyond the first coating area along the second direction, and a cut is provided on the edge portion. The cut is located on a side of the first empty foil area close to the first coating area in the third direction, and the first direction, the second direction and the third direction are perpendicular to each other.

2. The battery cell according to claim 1, characterized in that Along the first direction, the projection of the diaphragm and the projection of the first empty foil area have an overlapping area. Along the second direction, the length of the overlapping area is L1, and the length of the cut is L2, satisfying L2≤L1.

3. The battery cell according to claim 1, characterized in that Along the first direction, the edge portions of the two layers of the diaphragms located on both sides of the first pole piece are connected to each other.

4. The battery cell according to claim 1, characterized in that Along the third direction, a space is provided between the first empty foil area and the first coated area, and along the first direction, a projection of the cutout falls into the space.

5. The battery cell according to claim 4, characterized in that: The first coating area has a first edge at one end in the second direction and a second edge at one end in the third direction. The first coating area also has a third edge and a fourth edge connected to each other, the third edge is connected to the first edge, and the fourth edge is connected to the second edge. The edge of the first coating area that intersects with the first empty foil area along the second direction is the fourth edge. Along the third direction, the interval space is formed between the first empty foil area and the third edge. The third edge is inclined relative to the second direction, and the width of the interval space in the third direction gradually increases along the direction away from the fourth edge.

6. The battery cell according to claim 4, characterized in that The second pole piece has a first notch at a first corner, and when viewed along the first direction, the first empty foil area at least partially overlaps with the first notch.

7. The battery cell according to claim 6, characterized in that The first pole piece has a second notch at a second corner, and when viewed along the first direction, the first notch and the second notch do not overlap; The second pole piece includes a second empty foil area. When viewed along the first direction, the second empty foil area at least partially overlaps with the second notch. The second empty foil areas of multiple second pole pieces are stacked and gathered along the first direction.

8. The battery cell according to claim 7, characterized in that: The diaphragm has a third notch and a fourth notch. When viewed along the first direction, the first empty foil area at least partially overlaps with the third notch, and the second empty foil area at least partially overlaps with the fourth notch.

9. The battery cell according to claim 1, characterized in that: An insulating layer is provided on the first empty foil area, and the insulating layer is connected to the first active material layer.

10. The battery cell according to claim 9, characterized in that: Along the second direction, the insulating layer exceeds the edge of the diaphragm.

11. The battery cell according to claim 9, characterized in that Along the first direction, the projection of the diaphragm and the projection of the first empty foil area have an overlapping area. Along the second direction, the length of the overlapping area is L1, and the length of the insulating layer is L3, satisfying L3>L1.

12. The battery cell according to claim 9, characterized in that The thickness of the insulating layer is H1, and the thickness of the first active material layer is H2, satisfying H1≤H2.

13. The battery cell according to claim 9, characterized in that The thickness of the insulating layer is H, which satisfies 0.005 mm ≤ H ≤ 0.1 mm.

14. The battery cell according to claim 13, characterized in that: 0.01mm≤H≤0.05mm.

15. The battery cell according to claim 9, characterized in that The insulating layer includes a polymer material and an auxiliary material, wherein the polymer material includes at least one of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylate, styrene, acrylonitrile, polyamide, maleic anhydride, vinyl chloride and allyl chloride, and the auxiliary material includes carboxymethyl cellulose and polyoxyethylene ether.

16. The battery cell according to claim 1, characterized in that The first pole piece is a positive pole piece, and the second pole piece is a negative pole piece.

17. An electrical device, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 16, wherein the battery cell is used to provide electrical energy.

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