Electrode sheet, battery cell, battery, electrical device and manufacturing method for electrode sheet

Abstract

An electrode sheet, a battery cell, a battery, an electrical device and a manufacturing method for the electrode sheet, which can improve the yield of battery cells. The electrode sheet comprises: a first current collector, a first conductive layer and a first layer; the first current collector comprises a first body and a tab area connected to the edge of the first body; the first body comprises a coating area and an edge area, the first conductive layer being arranged on the surface of the coating area, the first layer being arranged on the surface of the edge area, and the porosity of the first layer being lower than that of the first conductive layer.

Description

Pole piece, battery cell, battery, electrical equipment and method for preparing pole piece

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application 202311163615.1 filed on September 8, 2023, entitled “Pole piece, battery cell, battery, electrical equipment and method for preparing pole piece,” and the entire contents of that application are incorporated into this application by reference. Technical Field

[0003] The embodiments of the present application relate to the field of battery technology, and in particular to a pole piece, a battery cell, a battery, an electrical device, and a method for preparing the pole piece. Background Art

[0004] With the increasing severity of environmental pollution, the new energy industry has attracted more and more attention. In the new energy industry, battery technology is an important factor in its development.

[0005] The development of battery technology requires consideration of numerous design factors, such as energy density, cycle life, and yield rate. The design of the electrode in a battery cell is crucial to its yield rate and performance. Therefore, developing an electrode that improves the yield rate of battery cells has become a pressing technical challenge in this field.

[0006] Summary of the Invention

[0007] The embodiments of the present application provide a pole piece, a battery cell, a battery, an electrical device, and a method for preparing the pole piece, which can improve the yield rate of the battery cell.

[0008] In a first aspect, a pole piece is provided, comprising: a first current collector, the first current collector comprising a first body and a pole tab region connected to the edge of the first body, the first body comprising a coating region and an edge region; a first conductive layer, the first conductive layer being arranged on the surface of the coating region; a first layer, the first layer being arranged on the surface of the edge region; wherein the porosity of the first layer is less than the porosity of the first conductive layer.

[0009] In an embodiment of the present application, the first current collector includes a first body, a first conductive layer is provided on the surface of the coated area of ​​the first body, a first layer is provided in the edge area of ​​the first body, and the porosity of the first layer is less than the porosity of the first conductive layer, that is, the density of the first layer is higher than the density of the first conductive layer. By increasing the density of the first layer, the problem of powder falling of the electrode to be cut during the cutting of the edge area can be improved, thereby reducing the risk of internal short circuit of the battery cell due to overlap of the positive electrode sheet and the negative electrode sheet, thereby improving the yield of the battery cell.

[0010] In some implementations, the porosity A1 of the first layer satisfies: 0%<A1≤50%. Thus, in the embodiment of the present application, the porosity of the first layer is less than the porosity of the first conductive layer, and the porosity A1 of the first layer is set to 0%<A1≤50%. This can effectively improve the problem of powder loss during cutting of the edge region of the electrode to be cut by increasing the density of the first layer, thereby reducing the risk of internal short circuits in the battery cell due to overlap of the positive and negative electrode sheets, thereby improving the yield rate of the battery cell.

[0011] In some implementations, the porosity A1 of the first layer satisfies the following: 20% ≤ A1 ≤ 30%. Thus, in the embodiment of the present application, the porosity of the first layer is less than the porosity of the first conductive layer, and the porosity A1 of the first layer is set to 20% ≤ A1 ≤ 30%. This can further improve the problem of powder loss during cutting of the edge region of the electrode to be cut by increasing the density of the first layer, thereby reducing the risk of internal short circuits in the battery cell due to overlap of the positive and negative electrode sheets, thereby improving the yield rate of the battery cell.

[0012] In some implementations, the ratio L1 / D1 between the dimension L1 of the edge region along the first direction and the thickness D1 of the first conductive layer satisfies: 10≤L1 / D1≤1000, preferably, 20≤L1 / D1≤100, wherein the first direction is perpendicular to the thickness direction of the pole piece. Thus, in the embodiment of the present application, by setting the ratio L1 / D1 between the dimension L1 of the edge region along the first direction and the thickness D1 of the first conductive layer to 10≤L1 / D1≤1000, and preferably, the value of L1 / D1 can also be set to 20≤L1 / D1≤100, it is possible to reduce the thermal impact on the first conductive layer during the laser die-cutting process, reduce the problem of powder loss caused by the thermal expansion of the first conductive layer during the cutting process of the pole piece, and thus improve the manufacturing performance of the battery.

[0013] In some implementations, the dimension L1 of the edge region along the first direction satisfies the following: 2 mm ≤ L1 ≤ 20 mm. Thus, in the embodiment of the present application, the dimension L1 of the edge region along the first direction is set to 2 mm ≤ L1 ≤ 20 mm. By adjusting the dimension L1 of the edge region along the first direction, the dimension of the coating region along the first direction is adjusted, thereby improving the conductivity of the first conductive layer and thereby increasing the energy density of the battery.

[0014] In some implementations, the dimension L1 of the edge region along the first direction satisfies the following: 3 mm ≤ L1 ≤ 6 mm. Thus, in the embodiment of the present application, by setting the dimension L1 of the edge region along the first direction to 3 mm ≤ L1 ≤ 6 mm, the dimension of the coating region along the first direction can be adjusted by adjusting the dimension L1 of the edge region along the first direction, thereby further improving the conductivity of the first conductive layer and thereby increasing the energy density of the battery.

[0015] In some implementations, the thickness D1 of the first conductive layer satisfies the following: 1 μm ≤ D1 ≤ 50 μm. Thus, in the embodiment of the present application, by setting the thickness D1 of the first conductive layer to 1 μm ≤ D1 ≤ 50 μm, the conductivity of the first conductive layer can be improved by controlling the thickness D1 of the first conductive layer, thereby increasing the energy density of the battery.

[0016] In some implementations, the material of the first conductive layer includes at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon. Thus, in the embodiments of the present application, by setting the material of the first conductive layer to at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon, the conductivity of the electrode sheet can be improved, thereby increasing the energy density of the battery.

[0017] In some implementations, the first layer extends to the tab region. Thus, in the embodiments of the present application, by extending the first layer to the tab region, that is, the first layer can be provided on at least a portion of the surface of the tab region, the tab region can be strengthened to reduce deformation and cracking of the pole piece during the cutting process and the subsequent winding process, thereby improving the performance of the battery, facilitating the processing and manufacturing of the pole piece, and improving the manufacturing performance of the battery.

[0018] In some implementations, the first layer further extends to the surface of the first conductive layer away from the first current collector. Thus, in the embodiment of the present application, by extending the first layer to the coating area, the processing and manufacturing of the pole piece is facilitated, thereby improving the manufacturing performance of the battery.

[0019] In some implementations, the first layer includes a second conductive layer. Thus, in the embodiments of the present application, by providing a second conductive layer on the surface of the edge region, the deposition area of ​​metal ions on the electrode can be increased, improving the conductivity of the electrode, thereby increasing the energy density of the battery.

[0020] In some implementations, the material of the second conductive layer includes at least one of the following materials: carbon nanotubes, graphene, and conductive graphite.

[0021] In the embodiment of the present application, by setting the material of the second conductive layer to at least one of the following materials: carbon nanotubes, graphene, and conductive graphite, the conductive performance of the electrode can be significantly improved, thereby increasing the energy density of the battery.

[0022] In some implementations, the thickness D2 of the second conductive layer satisfies the following: 2 μm ≤ D2 ≤ 150 μm, preferably, 70 μm ≤ D2 ≤ 120 μm. In the embodiment of the present application, by setting the thickness D2 of the second conductive layer to 2 μm ≤ D2 ≤ 150 μm, preferably, the thickness D2 of the second conductive layer can also be set to 70 μm ≤ D2 ≤ 120 μm, the conductivity of the second conductive layer can be improved by controlling the thickness D2 of the second conductive layer, thereby improving the energy density of the battery.

[0023] In some implementations, the material of the second conductive layer includes conductive carbon, and the thickness D2 of the second conductive layer satisfies the following: 10μm≤D2≤70μm. In the embodiment of the present application, when the material of the second conductive layer is set to conductive carbon, since the conductive carbon has a fluffy structure with a large porosity, the second conductive layer needs to be compacted after being coated on the edge area to reduce the porosity of the second conductive layer. Secondly, by setting the thickness D2 of the second conductive layer on the surface of the edge area to 10μm≤D2≤70μm, the conductivity of the second conductive layer can be improved by controlling the thickness D2 of the second conductive layer, thereby improving the energy density of the battery.

[0024] In some implementations, the first layer includes an insulating layer. Thus, in the embodiments of the present application, by providing an insulating layer on the surface of the edge region, the insulation performance of the electrode in the edge region can be improved, while effectively reducing metal deposition at the edge of the electrode, thereby improving the yield rate of the battery cell.

[0025] In some implementations, the thickness D3 of the insulating layer satisfies: 5μm≤D3≤100μm, preferably, 5μm≤D3≤20μm. Thus, in the embodiment of the present application, by setting the material of the second conductive layer as the insulating layer and setting the thickness D3 of the insulating layer to 5μm≤D3≤100μm, preferably, 5μm≤D3≤20μm, the deposition of metal ions at the edge of the electrode piece can be reduced by adjusting the thickness D3 of the insulating layer, while facilitating the processing and manufacturing of the electrode piece and improving the manufacturing performance of the battery.

[0026] In some implementations, the insulating layer comprises at least one of the following materials: boehmite, poly(hexafluoroethylene), EPDM rubber, and polyimide. Thus, in embodiments of the present application, by configuring the insulating layer to be made of at least one of the following materials: boehmite, poly(hexafluoroethylene), EPDM rubber, and polyimide, the insulation performance of the electrode in the edge region can be significantly improved, while simultaneously reducing the deposition of metal ions at the edge of the electrode. This also facilitates the processing and manufacturing of the electrode, thereby improving the manufacturing performance of the battery.

[0027] In some embodiments, the edge region includes a first edge region connected to a side of the coating region away from the tab region, and / or the edge region includes a second edge region connected between the tab region and the coating region.

[0028] In an embodiment of the present application, the edge area includes a first edge area, which is connected to the side of the coating area away from the pole lug area, and / or the edge area includes a second edge area, which is connected between the pole lug area and the coating area. In this way, when the electrode to be cut is cut, the edge of the edge area is the cutting edge, and the porosity of the second conductive layer is less than the porosity of the first conductive layer, that is, the density of the second conductive layer is higher than the density of the first conductive layer, which can effectively improve the powder falling problem in the edge area during the cutting process of the electrode to be cut, thereby reducing the risk of internal short circuit in the battery cell due to overlap of the positive electrode sheet and the negative electrode sheet, thereby improving the yield rate of the battery cell.

[0029] In a second aspect, a battery cell is provided, comprising an electrode assembly, wherein the electrode assembly comprises the electrode sheet according to any implementation of the first aspect.

[0030] In some implementations, the electrode sheet is a negative electrode sheet, and the electrode assembly further includes a positive electrode sheet, and an insulating layer is provided at a position of the positive electrode sheet corresponding to an edge area of ​​the negative electrode sheet.

[0031] In an embodiment of the present application, the electrode sheet is a negative electrode sheet, and the electrode assembly also includes a positive electrode sheet. By providing an insulating layer at a position of the positive electrode sheet corresponding to the edge area of ​​the negative electrode sheet, when metal ions are precipitated on the surface of the edge area of ​​the negative electrode sheet, due to the provision of the insulating layer, the risk of internal short circuit in the battery cell caused by overlapping of the positive electrode sheet and the negative electrode sheet can be effectively reduced, thereby improving the yield rate of the battery cell.

[0032] In some implementations, the battery cell is an alkali metal battery cell. Thus, in the embodiment of the present application, by setting the battery cell as an alkali metal battery cell, the energy density and reliability of the battery performance can be improved.

[0033] In a third aspect, a battery is provided, comprising the battery cell described in any implementation of the second aspect.

[0034] In a fourth aspect, an electrical device is provided, comprising: the battery described in the third aspect above, wherein the battery is used to provide electrical energy to the electrical device.

[0035] In some implementations, the electrical device may be a vehicle, a ship, or a spacecraft.

[0036] In a fifth aspect, a method for preparing a pole piece is provided, comprising: providing a second current collector, the second current collector comprising a second body and a pole ear forming area connected to the edge of the second body, the second body comprising a coating area and a cutting area; coating a first conductive layer on the surface of the coating area; coating a first layer on the surface of the cutting area; and cutting within the cutting area to form a pole piece in any possible implementation of the first aspect above; wherein the porosity of the first layer is less than the porosity of the first conductive layer.

[0037] In an embodiment of the present application, the second current collector includes a second body, a first conductive layer is coated on the surface of the coating area, and a first layer is coated on the surface of the cutting area. When cutting is performed in the cutting area, since the porosity of the first layer is less than the porosity of the first conductive layer, that is, the density of the first layer is higher than the density of the first conductive layer, the density of the first layer can be improved to improve the powder loss problem generated by the cutting process of the electrode to be cut in the cutting area, thereby reducing the risk of internal short circuit of the battery cell due to overlap of the positive electrode sheet and the negative electrode sheet, thereby improving the yield of the battery cell.

[0038] In some implementations, before cutting in the cutting region, the method further includes: coating the first layer on the surface of the region of the tab formation region adjacent to the second body. Thus, in the embodiment of the present application, by coating the first layer on the surface of the region of the tab formation region adjacent to the second body, the tab formation region can be reinforced to reduce deformation and cracking of the electrode sheet to be cut during the cutting process and subsequent winding process, thereby improving the performance of the battery.

[0039] In some implementations, before cutting within the cutting region, the method further includes: coating the first layer on the surface of the first conductive layer away from the second current collector. Thus, in the embodiments of the present application, by coating the first layer on the surface of the first conductive layer away from the second current collector, during the cutting process of the electrode to be cut, such as during laser die-cutting, the thermal impact of the laser die-cutting process on the first conductive layer near the cutting region can be reduced, and ablation at the edges of the cutting position can be reduced, thereby improving the performance of the battery.

[0040] In some implementations, the first layer includes a second conductive layer. Thus, in the embodiments of the present application, by providing the second conductive layer on the surface of the cutting area, the deposition area of ​​the metal ions on the target electrode can be increased, thereby improving the conductivity of the electrode and thus increasing the energy density of the battery.

[0041] In some implementations, the first layer includes an insulating layer. Thus, in the embodiments of the present application, by providing an insulating layer on the surface of the cut area, the insulation performance of the electrode in the edge area can be improved, while effectively reducing metal deposition at the edge of the electrode, thereby improving the yield rate of the battery cell.

[0042] In some embodiments, the coating area includes at least two sub-coating areas, and the first sub-cutting area of ​​the cutting area is arranged between the two sub-coating areas. The method also includes: cutting within the first sub-cutting area to form a first edge area on the side of the coating area away from the tab formation area.

[0043] In an embodiment of the present application, a first sub-cutting area in the cutting area is set between two sub-coating areas, and cutting is performed in the first sub-cutting area to form a first edge area on the side of the coating area away from the tab formation area. Since the porosity of the first layer coated in the first sub-cutting area is smaller than the porosity of the first conductive layer, that is, the density of the first layer is higher than the density of the first conductive layer, the powder falling problem during the cutting process can be reduced, thereby reducing the risk of internal short circuit of the battery cell, and thereby improving the yield rate of the battery cell.

[0044] In some implementations, the second sub-cutting area in the cutting area is arranged between the tab forming area and the coating area, and the method further includes: cutting in the second sub-cutting area to form the tab area and the second edge area of ​​the target pole piece, and the second edge area is connected between the tab area and the coating area. In this way, in an embodiment of the present application, when the pole piece to be cut is subjected to a cutting process, such as a laser die-cutting process, the die-cutting position is located in the second sub-cutting area between the tab forming area and the coating area. Since the porosity of the first layer coated on the second sub-cutting area is less than the porosity of the first conductive layer, that is, the density of the first layer is higher than the density of the first conductive layer, the ablation phenomenon occurring at the die-cutting position of the cutting area during the laser die-cutting process can be reduced, and the powder loss phenomenon during the cutting process can be reduced, thereby reducing the risk of internal short circuit of the battery cell, and thus improving the yield rate of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] 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. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0046] FIG1 is a schematic structural diagram of a vehicle provided in one embodiment of the present application.

[0047] FIG2 is a schematic structural diagram of a battery provided in one embodiment of the present application.

[0048] FIG3 is a schematic structural diagram of a battery cell provided in one embodiment of the present application.

[0049] FIG4 is a schematic cross-sectional view of a pole piece provided in one embodiment of the present application.

[0050] FIG5 is a schematic cross-sectional view of a pole piece provided in another embodiment of the present application.

[0051] FIG6 is a schematic cross-sectional view of a pole piece provided in another embodiment of the present application.

[0052] FIG7 is a schematic cross-sectional view of a pole piece provided in another embodiment of the present application.

[0053] FIG8 is a schematic cross-sectional view of a pole piece provided in another embodiment of the present application.

[0054] FIG9 is a schematic cross-sectional view of a pole piece provided in another embodiment of the present application.

[0055] FIG10 is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0056] FIG11 is a schematic cross-sectional view of a pole piece provided in another embodiment of the present application.

[0057] FIG12 is a partial cross-sectional schematic diagram of an electrode assembly provided in one embodiment of the present application.

[0058] FIG13 is a schematic flow chart of a method for preparing a pole piece provided in one embodiment of the present application.

[0059] FIG14 is a schematic cross-sectional view of a pole piece to be cut provided in one embodiment of the present application.

[0060] FIG15 is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0061] FIG16 is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0062] FIG17 is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0063] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0064] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the embodiments of the present application, but are not intended to limit the scope of the embodiments of the present application. That is, the embodiments of the present application are not limited to the described embodiments.

[0065] Unless otherwise defined, all technical and scientific terms used in the embodiments of the present application have the same meanings as those commonly understood by technicians in the technical fields belonging to the embodiments of the present application; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application; the terms "including" and "having" in the description and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0066] In the description of the embodiments of this application, the technical terms "first," "second," etc. are used only to distinguish different objects and should not be understood to indicate or imply relative importance or to implicitly indicate the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise specifically defined.

[0067] 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. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0068] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0069] It should be understood that in the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0070] 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 referred device or element 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.

[0071] 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.

[0072] 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. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0073] The battery mentioned in the embodiments of the present application may include one or more battery cells to provide a single physical module with higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel or in hybrid through a busbar.

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

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

[0076] In some implementations, the box can serve as part of the chassis structure of the vehicle. For example, a portion of the box can become at least a portion of the floor of the vehicle, or a portion of the box can become at least a portion of the crossbeam and longitudinal beam of the vehicle.

[0077] In some implementations, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0078] It should be understood that the battery cells in the embodiments of the present application include but are not limited to lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0079] In some implementations, the battery cell in the embodiments of the present application may be a metal battery. Specifically, the metal battery may include a lithium metal secondary battery, a sodium metal battery, or a magnesium metal battery.

[0080] In some implementations, a battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0081] In some implementations, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0082] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0083] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0084] In some implementations, a metal foam may be used as the positive electrode. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam, among others. When the metal foam is used as the positive electrode, the surface of the metal foam may or may not be provided with a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled and / or deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0085] In some implementations, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0086] As an example, the negative electrode current collector may be a metal foil, a metal foam, or a composite current collector. For example, as the metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam, etc. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0087] In some implementations, the battery cells in the embodiments of the present application may be negative electrode metal-free batteries.

[0088] In some implementations, the battery cell in the embodiments of the present application may be a negative electrode-free sodium secondary battery.

[0089] A negative electrode-free sodium secondary battery refers to a battery cell that does not actively set a negative electrode active material layer on the negative electrode side during the manufacturing process of the battery cell. For example, during the manufacturing process of the battery cell, a sodium metal or carbonaceous active material layer is not set at the negative electrode through processes such as coating or deposition to form a negative electrode active material layer. During the first charge, sodium ions gain electrons on the anode side and deposit on the surface of the current collector to form a sodium metal phase. During discharge, metallic sodium can be converted into sodium ions and return to the positive electrode, realizing cyclic charge and discharge. Compared with other sodium secondary batteries, negative electrode-free sodium secondary battery cells can achieve higher energy density due to the lack of a negative electrode active material layer.

[0090] In some implementations, in order to improve the performance of battery cells, some functional coatings, such as carbonaceous materials, metal oxides, alloys, etc., can be provided on the negative electrode side of the negative electrode-free sodium secondary battery to improve the conductivity of the negative electrode current collector and improve the uniformity of the deposited sodium metal.

[0091] In some implementations, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0092] In some implementations, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0093] In some implementations, the separator is a separator. The present invention has no particular restrictions on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be used.

[0094] As an example, the main material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics.

[0095] In some implementations, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to both transport ions and isolate the positive and negative electrodes.

[0096] In some implementations, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The present application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on needs. The electrolyte can be liquid, gel, or solid.

[0097] In some implementations, the electrode assembly may be a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0098] In some implementations, the electrode assembly is a laminated structure. As an example, multiple positive and negative electrodes may be provided, and the multiple positive and negative electrodes may be alternately stacked.

[0099] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0100] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0101] As an example, a plurality of separators may be provided, each of which is disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0102] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0103] In some implementations, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0104] In some implementations, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0105] In some implementations, a battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0106] It should be understood that in the embodiments of the present application, an energy storage device is a device for storing energy, which is generally capable of accommodating one or more energy storage elements, wherein the energy storage element can be, for example, a battery. A battery can also be referred to as an electrical box, which includes a box body and one or more battery cells encapsulated by the box body. For example, battery cells can include but are not limited to: lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries. Battery cells can be cylindrical, flat, rectangular, or other shapes.

[0107] In some implementations, the energy storage device may also include functional components to manage or assist in the operation of the multiple energy storage elements. For example, the energy storage device may include thermal management components, including but not limited to air conditioning components, fan components, water cooling pipes, etc., which can be used to manage the internal thermal state of the energy storage device to adjust the internal temperature of the energy storage device. Another example is a control box that can be included in the energy storage device to monitor and control various states of the energy storage device.

[0108] Currently, the design of the pole piece in a battery cell is crucial to the yield rate and performance of the battery cell. Typically, a low-density conductive coating is applied to the surface of the pole piece. During the subsequent die-cutting process, if the laser die-cutting power is low, there is a risk that the coating cannot be cut off, and the remaining portion is prone to forming burrs. When the laser die-cutting power is high, the edges of the cut area are ablated, making the conductive coating brittle and prone to powdering, generating dust and burrs. This can lead to the risk of short circuits within the battery cell due to overlapping of the positive and negative pole pieces, thus affecting the yield rate of the battery cell. Therefore, how to provide a pole piece to improve the yield rate of battery cells has become a technical problem that needs to be urgently addressed in this field.

[0109] In view of this, an embodiment of the present application provides a pole piece, comprising: a first current collector, the first current collector comprising a first body and a tab region connected to the edge of the first body, the first body comprising a coating region and an edge region; a first conductive layer, the first conductive layer disposed on the surface of the coating region; and a first layer, the first layer disposed on the surface of the edge region; wherein the porosity of the first layer is less than the porosity of the first conductive layer. Thus, in an embodiment of the present application, the first current collector comprises a first body, the first conductive layer is disposed on the surface of the coating region of the first body, the first layer is disposed on the edge region of the first body, and the porosity of the first layer is less than the porosity of the first conductive layer, that is, the density of the first layer is higher than the density of the first conductive layer. By improving the density of the first layer, the problem of powder shedding during cutting of the edge region of the pole piece to be cut can be improved, thereby reducing the risk of internal short circuit of the battery cell due to overlap of the positive pole piece and the negative pole piece, thereby improving the yield rate of the battery cell.

[0110] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be fuel-powered vehicles, gas-powered vehicles, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include aircraft, 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. Power tools include metal cutting tools, grinding tools, assembly tools, and railway tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.

[0111] It should be understood that the technical solutions described in the embodiments of the present application are not limited to the electrical equipment described above, but can also be applied to all devices that use batteries. For the sake of simplicity, the following embodiments are described in detail using the electrical equipment as a vehicle as an example.

[0112] For example, as shown in FIG1 , it is a structural schematic diagram of a vehicle 1 provided in an embodiment of the present application. The vehicle 1 may be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A motor 40, a controller 30 and a battery 10 may be provided inside the vehicle 1. The controller 30 is used to control the battery 10 to supply power to the motor 40. For example, a battery 10 may be provided at the bottom, front or rear of the vehicle 1. The battery 10 may be used to power the vehicle 1. For example, the battery 10 may be used as an operating power source for the vehicle 1, for the circuit system of the vehicle 1, for example, for the working power requirements during the startup, navigation and operation of the vehicle 1. In another implementation of the present application, the battery 10 may not only be used 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.

[0113] In order to meet different power usage requirements, the battery 10 in the embodiment of the present application can be a battery cell group or a battery pack. The battery 10 may include at least one battery cell group, and the battery cell group includes a plurality of battery cells, wherein the plurality of battery cells can be electrically connected in series, in parallel, or in mixed connection to form a battery 10, wherein mixed connection refers to a mixture of series and parallel connection. The battery 10 can also be referred to as a battery pack. For example, a plurality of battery cells can first be connected in series, in parallel, or in mixed connection to form a battery module, and a plurality of battery modules can then be connected in series, in parallel, or in mixed connection to form a battery 10. In other words, a plurality of battery cells can directly form a battery 10, or they can first be formed into a battery module, and then the battery modules can be formed into a battery 10.

[0114] In some implementations, the battery 10 may include multiple battery cells. For example, FIG2 is a schematic diagram of the structure of a battery 10 according to one embodiment of the present application. The battery 10 may include multiple battery cells 20. The battery 10 may also include a housing 11 having a hollow interior and housing the multiple battery cells 20. For example, the multiple battery cells 20 may be connected in parallel, in series, or in a mixed combination and then placed in the housing 11.

[0115] In some implementations, the battery 10 may further include other structures, which will not be described in detail here. For example, the battery 10 may further include a busbar component, which is used to achieve electrical connection between multiple battery cells 20, such as parallel connection, series connection, or mixed connection. Specifically, the busbar component can achieve electrical connection between the battery cells 20 by connecting the electrode terminals of the battery cells 20. Furthermore, the busbar component can be fixed to the electrode terminals of the battery cells 20 by welding. The electrical energy of the multiple battery cells 20 can be further led out through the box through a conductive mechanism. Optionally, the conductive mechanism may also belong to the busbar component.

[0116] In the embodiment of the present application, the number of battery cells 20 can be set to any value according to different power requirements. Multiple battery cells 20 can be connected in series, parallel or hybrid to achieve a larger capacity or power. Since the number of battery cells 20 included in each battery 10 may be large, for ease of installation, the battery cells 20 can be grouped, and each group of battery cells 20 constitutes a battery module. The number of battery cells 20 included in the battery module is not limited and can be set according to demand. The battery 10 may include multiple battery modules, which can be connected in series, parallel or hybrid.

[0117] As shown in FIG3 , it is a schematic structural diagram of a battery cell 20 according to an embodiment of the present application. The battery cell 20 includes one or more electrode assemblies 22, a shell 211 and a cover plate 212. The shell 211 and the cover plate 212 form an outer shell or battery box 21. The walls of the shell 211 and the cover plate 212 are both referred to as the walls of the battery cell 20. For a rectangular battery cell 20, the walls of the shell 211 include a bottom wall and four side walls. The shell 211 is determined according to the shape of the one or more electrode assemblies 22 after combination. For example, the shell 211 can be a hollow cuboid, cube or cylinder, and one of the faces of the shell 211 has an opening so that one or more electrode assemblies 22 can be placed in the shell 211. For example, when the shell 211 is a hollow cuboid or cube, one of the planes of the shell 211 is an open surface, that is, the plane does not have a wall, so that the inside and outside of the shell 211 are connected. When the housing 211 is a hollow cylinder, the end surface of the housing 211 is an open surface, that is, the end surface has no wall, so that the inside and outside of the housing 211 are connected. The cover plate 212 covers the opening and is connected to the housing 211 to form a closed cavity for accommodating the electrode assembly 22. The housing 211 is filled with an electrolyte, such as an electrolyte solution.

[0118] The battery cell 20 may also include two electrode terminals 214, which may be disposed on the cover plate 212. The cover plate 212 is typically flat, with the two electrode terminals 214 secured to the flat surface of the cover plate 212. The two electrode terminals 214 are respectively a positive electrode terminal 214a and a negative electrode terminal 214b. Each electrode terminal 214 is provided with a corresponding connecting member, also known as a current collecting member, located between the cover plate 212 and the electrode assembly 22 to electrically connect the electrode assembly 22 to the electrode terminals 214.

[0119] As shown in FIG3 , each electrode assembly 22 has a first electrode tab 221 a and a second electrode tab 222 a. The polarities of the first electrode tab 221 a and the second electrode tab 222 a are opposite. For example, when the first electrode tab 221 a is a positive electrode tab, the second electrode tab 222 a is a negative electrode tab.

[0120] In the battery cell 20 , the electrode assembly 22 can be provided as a single one or multiple ones according to actual use requirements. As shown in FIG3 , two independent electrode assemblies 22 are provided in the battery cell 20 .

[0121] A pressure relief mechanism 213 may also be provided on the battery cell 20. The pressure relief mechanism 213 is used to be activated to release the internal pressure or temperature of the battery cell 20 when the internal pressure or temperature reaches a threshold value.

[0122] The pressure relief mechanism 213 may have various possible pressure relief structures. For example, the pressure relief mechanism 213 may be a temperature-sensitive pressure relief mechanism configured to melt when the internal temperature of the battery cell 20 equipped with the pressure relief mechanism 213 reaches a threshold; and / or the pressure relief mechanism 213 may be a pressure-sensitive pressure relief mechanism configured to rupture when the internal pressure of the battery cell 20 equipped with the pressure relief mechanism 213 reaches a threshold.

[0123] FIG4 is a schematic cross-sectional view of a pole piece 50 provided in one embodiment of the present application, and FIG5 is a schematic cross-sectional view of a pole piece 50 provided in another embodiment of the present application. FIG4 and FIG5 can be understood as schematic cross-sectional views of the same pole piece 50 in different directions. For example, FIG4 can be a schematic cross-sectional view of the pole piece 50 perpendicular to the thickness direction of the pole piece 50, and FIG5 can be a schematic cross-sectional view of the pole piece 50 perpendicular to the length direction of the pole piece 50.

[0124] It should be understood that in the embodiments of the present application, for the convenience of description, three directions are defined here, as shown in Figures 4 and 5. The first direction X may be the length direction of the pole piece 50, and the first direction X is perpendicular to the second direction Y and the third direction Z; the second direction Y may be the width direction of the pole piece 50, and the second direction Y is perpendicular to the first direction X and the third direction Z; the third direction Z may be the height direction of the pole piece 50, and the third direction Z is perpendicular to the first direction X and the second direction Y, and the third direction Z may also refer to the thickness direction of the pole piece 50.

[0125] In some embodiments, as shown in Figures 4 and 5, the pole piece 50 includes: a first current collector 510, a first conductive layer 560 and a first layer 550, the first current collector 510 includes a first body and a pole ear area 540 connected to the edge of the first body, the first body includes a coating area 520 and an edge area 530, the first conductive layer 560 is arranged on the surface of the coating area 520, and the first layer 550 is arranged on the surface of the edge area 530, wherein the porosity of the first layer 550 is less than the porosity of the first conductive layer 560.

[0126] It should be understood that, in the embodiment of the present application, the first conductive layer 560 being disposed on the surface of the coating region 520 may mean that the first conductive layer 560 may be disposed on at least one of the two surfaces of the coating region 520 in a direction perpendicular to the thickness of the coating region 520. In the embodiment of the present application, the first layer 550 being disposed on the surface of the edge region 530 may mean that the first layer 550 may be disposed on at least one of the two surfaces of the edge region 530 in a direction perpendicular to the thickness of the edge region 530.

[0127] It should also be understood that in the embodiment of the present application, the rectangular pole piece 50 shown in the above-mentioned Figures 4 and 5 is only an example, and the shape of the pole piece 50 includes but is not limited to a square, a parallelogram and a polygon.

[0128] It should also be understood that in the embodiment of the present application, the first current collector 510 may be a negative electrode current collector or a positive electrode current collector. When the first current collector 510 is a negative electrode current collector, the negative electrode current collector may be a metal foil, foam metal or a composite current collector; when the first current collector 510 is a positive electrode current collector, the positive electrode current collector may be a metal foil or a composite current collector.

[0129] It should also be understood that in the embodiment of the present application, the edge area 530 can be understood as an area set at the edge of the first body of the first current collector 510. In some implementations, the edge area 530 can be set in an area of ​​the first body close to the tab area 540. In other implementations, the edge area 530 can also be set in an area of ​​the first body away from the tab area 540.

[0130] It should also be understood that in the embodiments of the present application, the porosity of the first layer 550 and the first conductive layer 560 in the embodiments of the present application can be measured using a true density method. True density refers to the actual mass of a solid substance per unit volume when the material is in an absolutely dense state, that is, the density after removing internal voids or voids between particles. Typically, a true density analyzer can be used to measure the actual volume and true density of a sample. A true density analyzer utilizes the Archimedean principle of gas expansion displacement and Bohr's law of small molecular diameter inert gases under certain conditions to accurately measure the true volume of the sample by measuring the volume of gas discharged from the sample in the test chamber.

[0131] In some implementations, when measuring porosity using the true density method, a sample to be tested is first prepared. For example, a pole piece with only the first layer 550 on the surface can be obtained. The sample is then placed in a true density detector. Helium is used as the medium gas. After gradually pressurizing the measurement chamber in the true density detector to a preset value, helium is introduced into the expansion chamber. The equilibrium pressure in the two chambers during the experiment is automatically recorded by the instrument, and the true volume V1 of the sample is calculated according to Bohr's law. The apparent volume V2 of the sample is then measured. The apparent volume V2 can be calculated by measuring the thickness of the sample and the area of ​​the surface perpendicular to the thickness direction of the sample. Secondly, the difference between the apparent volume V2 and the true volume V1 can be further calculated, and the porosity of the sample can be characterized by the ratio of the difference to the true volume V1 of the sample. It should also be understood that in the embodiment of the present application, the true volume V1 of the sample can be measured multiple times by the true density detector, and the porosity of the sample can be calculated by taking the average of the multiple true volumes V1.

[0132] In an embodiment of the present application, the first current collector 510 includes a first body, a first conductive layer 560 is provided on the surface of the coated area 520 of the first body, and a first layer 550 is provided in the edge area 530 of the first body, and the porosity of the first layer 550 is less than the porosity of the first conductive layer 560, that is, the density of the first layer 550 is higher than the density of the first conductive layer 560. By increasing the density of the first layer 550, the powder loss problem of the electrode to be cut during the cutting process of the edge area 530 can be improved, thereby reducing the risk of internal short circuit of the battery cell 20 due to overlap of the positive electrode plate 502 and the negative electrode plate 501, thereby improving the yield of the battery cell 20.

[0133] It should be understood that in the embodiment of the present application, when the first layer 550 is coated on the surface of the above-mentioned edge area 530, the following methods are included but not limited to: first, the first layer 550 is directly coated on the surface of the edge area 530, and the porosity of the first layer 550 is less than the porosity of the first conductive layer 560 coated on the surface of the coating area 520, and the thickness of the first layer 550 can be greater than, equal to or less than the thickness of the first conductive layer 560, and the porosity of the first layer 550 on the obtained electrode 50 is less than the porosity of the first conductive layer 550; second, the first layer 550 is first coated on the surface of the edge area 530, the porosity of the first layer 550 is equal to the porosity of the first conductive layer 560, and the thickness of the first layer 550 is greater than or equal to the thickness of the first conductive layer 560, and then the first layer 550 is compacted so that the porosity of the first layer 550 on the edge area 530 after compaction is less than the porosity of the first conductive layer 550.

[0134] In some implementations, the porosity A1 of the first layer 550 satisfies: 0%<A1≤50%.

[0135] It should be understood that in the embodiments of the present application, the porosity A1 of the first layer 550 refers to the percentage of the void volume in the material corresponding to the first layer 550 to the total volume of the material in its natural state. The higher the porosity of the material, the lower its density. It should also be understood that the porosity A1 in the embodiments of the present application can also be referred to as porosity. Specifically, methods for calculating the porosity A1 of the first layer 550 include but are not limited to true density method, buoyancy method, gas permeation method, image analysis method, specific surface area method, and adsorption method.

[0136] Illustratively, the porosity A1 of the first layer 550 in the embodiment of the present application may be: 2%, 4%, 6%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%, or its value is within the range obtained by combining any two of the above values.

[0137] In an embodiment of the present application, the porosity A1 of the first layer 550 is less than the porosity of the first conductive layer 560, and the porosity A1 of the first layer is set to 0%<A1≤50%. By increasing the density of the first layer 550, the powder loss problem of the electrode to be cut during the cutting of the edge area 530 can be effectively improved, thereby reducing the risk of internal short circuit in the battery cell 20 due to overlap between the positive electrode 502 and the negative electrode 501, thereby improving the yield of the battery cell 20.

[0138] In some other implementations, the porosity A1 of the first layer 550 satisfies: 20%≤A1≤30%.

[0139] Illustratively, the porosity A1 of the first layer 550 in the embodiment of the present application may be: 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%, or its value is within the range obtained by combining any two of the above values.

[0140] In an embodiment of the present application, the porosity A1 of the first layer 550 is less than the porosity of the first conductive layer 560, and the porosity A1 of the first layer 550 is set to 20%≤A1≤30%. By increasing the density of the first layer 550, the powder loss problem of the electrode to be cut during the cutting of the edge area 530 can be further improved, thereby reducing the risk of internal short circuit in the battery cell 20 due to overlap between the positive electrode 502 and the negative electrode 501, thereby improving the yield of the battery cell 20.

[0141] In some implementations, a ratio L1 / D1 between a dimension L1 of the edge region 530 along a first direction and a thickness D1 of the first conductive layer 560 satisfies: 10≤L1 / D1≤1000, preferably, 20≤L1 / D1≤100, wherein the first direction is perpendicular to the thickness direction of the pole piece 50. Exemplarily, in the embodiment of the present application, the first direction may be direction Y or direction X.

[0142] For example, the ratio L1 / D1 between the dimension L1 of the edge area 530 along the first direction and the thickness D1 of the first conductive layer 560 in the embodiment of the present application may be: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900 or 1000, or its value is within the range obtained by combining any two of the above values.

[0143] In an embodiment of the present application, by setting the ratio L1 / D1 between the dimension L1 of the edge area 530 along the first direction and the thickness D1 of the first conductive layer 560 to 10≤L1 / D1≤1000, and preferably, the value of L1 / D1 can also be set to 20≤L1 / D1≤100, the thermal impact on the first conductive layer 560 during the laser die-cutting process can be reduced, and the powder loss problem of the pole piece 50 caused by the thermal expansion of the first conductive layer 560 during the cutting process can be reduced, thereby improving the manufacturing performance of the battery 10.

[0144] In some implementations, the dimension L1 of the edge region 530 along the first direction satisfies: 2 mm ≤ L1 ≤ 20 mm. For example, in the embodiment of the present application, the first direction may be direction Y or direction X.

[0145] It should be understood that in the embodiment of the present application, as shown in FIG4 , the pole piece 50 may be provided with two edge regions 530 along the direction Y. For example, the edge region 530 of the first body of the first current collector 510 away from the tab region 540 may be a first edge region 531, and the edge region 530 of the first body of the first current collector 510 close to the tab region 540 may be a second edge region 532. The size of the first edge region 531 along the direction Y may be the same as or different from the size of the second edge region 532 along the direction Y.

[0146] Illustratively, the dimension L1 of the edge area 530 along the first direction in the embodiment of the present application may be: 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 12mm, 14mm, 16mm, 18mm or 20mm, or its value is within the range obtained by combining any two of the above values.

[0147] In an embodiment of the present application, the dimension L1 of the edge area 530 along the first direction is set to 2mm≤L1≤20mm, so as to adjust the dimension L1 of the edge area 530 along the first direction to adjust the dimension of the coating area 520 along the first direction, so as to improve the conductivity of the first conductive layer 560, thereby improving the energy density of the battery 10.

[0148] In some other implementations, the dimension L1 of the edge region 530 along the first direction satisfies: 3 mm ≤ L1 ≤ 6 mm. For example, in the embodiment of the present application, the first direction may be direction Y or direction X.

[0149] Illustratively, the dimension L1 of the edge area 530 along the first direction in the embodiment of the present application may be: 3mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4mm, 4.2mm, 4.4mm, 4.6mm, 4.8mm, 5mm, 5.2mm, 5.4mm, 5.6mm, 5.8mm or 6mm, or its value is within the range obtained by combining any two of the above values.

[0150] In the embodiment of the present application, by setting the dimension L1 of the edge area 530 along the first direction to 3mm≤L1≤6mm, the dimension L1 of the coating area 520 along the first direction is adjusted by adjusting the dimension L1 of the edge area 530 along the first direction, so as to further improve the conductivity of the first conductive layer 560, thereby improving the energy density of the battery 10.

[0151] In some implementations, the thickness D1 of the first conductive layer 560 satisfies: 1 μm≤D1≤50 μm.

[0152] Exemplarily, the thickness D1 of the first conductive layer 560 may be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm, or its value is within the range obtained by combining any two of the above values.

[0153] In the embodiment of the present application, by setting the thickness D1 of the first conductive layer 560 to 1 μm≤D1≤50 μm, the conductivity of the first conductive layer 560 can be improved by controlling the thickness D1 of the first conductive layer 560 , thereby improving the energy density of the battery 10 .

[0154] In some implementations, the material of the first conductive layer 560 includes at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon. Thus, in the embodiment of the present application, by setting the material of the first conductive layer 560 to be at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon, the conductivity of the pole piece 50 can be improved, thereby increasing the energy density of the battery 10.

[0155] FIG6 is a schematic cross-sectional view of a pole piece 50 provided in another embodiment of the present application, and FIG7 is a schematic cross-sectional view of a pole piece 50 provided in another embodiment of the present application. FIG6 and FIG7 can be understood as schematic cross-sectional views of the same pole piece 50 in different directions. For example, FIG6 can be a schematic cross-sectional view of the pole piece 50 perpendicular to the thickness direction of the pole piece 50, and FIG7 can be a schematic cross-sectional view of the pole piece 50 perpendicular to the length direction of the pole piece 50.

[0156] In some implementations, as shown in FIG. 6 and FIG. 7 , the first layer 550 extends to the tab region 540 .

[0157] It should be understood that in the embodiment of the present application, the first layer 550 extending to the tab region 540 means that the first layer 550 can be provided on at least one of the two surfaces of the tab region 540 in a direction perpendicular to the thickness of the tab region 540. It should also be understood that the first layer 550 can be provided in at least a portion of the tab region 540.

[0158] In an embodiment of the present application, by extending the first layer 550 to the tab area 540, that is, the first layer 550 can be arranged on at least a portion of the surface of the tab area 540, the tab area 540 can be strengthened to reduce the deformation and cracking of the pole piece 50 during the cutting process and the subsequent winding process, thereby improving the performance of the battery 10, and facilitating the processing and manufacturing of the pole piece 50, thereby improving the manufacturing performance of the battery 10.

[0159] In some implementations, as shown in FIG7 , the first layer 550 further extends to the surface of the first conductive layer 560 away from the first current collector 510. Thus, in the embodiment of the present application, by extending the first layer 550 to the surface of the first conductive layer 560 away from the first current collector 510, the processing and manufacturing of the electrode sheet 50 is facilitated, thereby improving the manufacturing performance of the battery 10.

[0160] In some implementations, the first layer 550 includes a second conductive layer.

[0161] It should be understood that in the embodiment of the present application, the porosity of the second conductive layer is less than the porosity of the first conductive layer 560, that is, the density of the second conductive layer is greater than the density of the first conductive layer 560, and the second conductive layer can be arranged on at least one of the two surfaces of the edge area 530 perpendicular to the thickness direction of the edge area 530.

[0162] It should be understood that in the embodiment of the present application, as shown in Figures 5 and 7, the thickness of the second conductive layer can be represented by D2.

[0163] In the embodiment of the present application, by providing a second conductive layer on the surface of the edge region 530 , the deposition area of ​​metal ions on the electrode 50 can be increased, thereby improving the conductive performance of the electrode 50 and increasing the energy density of the battery 10 .

[0164] In some implementations, the material of the second conductive layer includes at least one of the following materials: carbon nanotubes, graphene, and conductive graphite. Thus, in the embodiments of the present application, by setting the material of the second conductive layer to at least one of the following materials: carbon nanotubes, graphene, and conductive graphite, the conductivity of the pole piece 50 can be significantly improved, thereby increasing the energy density of the battery 10.

[0165] In some implementations, when the material of the second conductive layer includes at least one of the following materials: carbon nanotubes, graphene, and conductive graphite, the thickness D2 of the second conductive layer satisfies: 2μm≤D2≤150μm, preferably, 70μm≤D2≤120μm.

[0166] Exemplarily, the thickness D2 of the second conductive layer in the embodiment of the present application may be: 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 15μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm or 150μm, or its value is within the range obtained by combining any two of the above values.

[0167] In an embodiment of the present application, when the material of the second conductive layer includes at least one of the following materials: carbon nanotubes, graphene, and conductive graphite, by setting the thickness D2 of the second conductive layer to 2μm≤D2≤150μm, preferably, the thickness D2 of the second conductive layer can also be set to: 70μm≤D2≤120μm, the conductivity of the second conductive layer can be improved by controlling the thickness D2 of the second conductive layer, thereby improving the energy density of the battery 10.

[0168] In some implementations, the material of the second conductive layer includes conductive carbon, and the thickness D2 of the second conductive layer satisfies: 10 μm≤D2≤70 μm.

[0169] Illustratively, the thickness D2 of the second conductive layer in the embodiment of the present application may be: 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 25μm, 30μm, 40μm, 50μm, 60μm or 70μm, or its value is within the range obtained by combining any two of the above values.

[0170] It should be understood that in the embodiment of the present application, when the material of the second conductive layer is set to conductive carbon, after the conductive carbon is coated on the surface of the electrode 50, since the conductive carbon has a fluffy structure with a large porosity, it is necessary to compact it to reduce the porosity of the second conductive layer. In some implementations, when the porosity of the second conductive layer is less than the porosity of the first conductive layer 560, the thickness D2 of the second conductive layer can be greater than, less than, or equal to the thickness D1 of the first conductive layer 560.

[0171] In an embodiment of the present application, when the material of the second conductive layer is set to conductive carbon, since the conductive carbon has a fluffy structure with a large porosity, the second conductive layer needs to be compacted after being coated on the edge area to reduce the porosity of the second conductive layer. Secondly, by setting the thickness D2 of the second conductive layer on the surface of the edge area to 10μm≤D2≤70μm, the conductivity of the second conductive layer can be improved by controlling the thickness D2 of the second conductive layer, thereby improving the energy density of the battery.

[0172] In some implementations, as shown in FIG. 4 to FIG. 7 , the first layer 550 includes an insulating layer.

[0173] It should be understood that in the embodiment of the present application, the porosity of the insulating layer is less than the porosity of the first conductive layer 560, that is, the density of the insulating layer is greater than the density of the first conductive layer 560, and the insulating layer can be arranged on at least one of the two surfaces of the edge area 530 perpendicular to the thickness direction of the edge area 530.

[0174] In an embodiment of the present application, when cutting the electrode to be cut, an insulating layer is set on the surface of the edge area 530, and the porosity of the insulating layer is less than the porosity of the first conductive layer 560, that is, the density of the insulating layer is higher than the density of the first conductive layer 560, which can effectively improve the powder falling problem during the cutting process, significantly reduce the risk of internal short circuit of the battery cell 20, and effectively reduce the deposition of metal at the edge position of the electrode 50, thereby improving the yield of the battery cell 20.

[0175] It should be understood that in the embodiment of the present application, as shown in FIG. 5 and FIG. 7 , the thickness of the insulating layer can be represented by D3.

[0176] In some implementations, the thickness D3 of the insulating layer satisfies: 5 μm≤D3≤100 μm, preferably, 5 μm≤D3≤20 μm.

[0177] Exemplarily, the thickness D3 of the insulating layer in the embodiment of the present application may be: 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 25μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm, or its value is within the range obtained by combining any two of the above values.

[0178] In an embodiment of the present application, by setting the material of the second conductive layer as an insulating layer, and setting the thickness D3 of the insulating layer to 5μm≤D3≤100μm, preferably, 5μm≤D3≤20μm, the deposition of metal ions at the edge of the electrode 50 can be reduced by adjusting the thickness D3 of the insulating layer, while facilitating the processing and manufacturing of the electrode 50 and improving the manufacturing performance of the battery 10.

[0179] In some implementations, the insulating layer comprises at least one of the following materials: boehmite, poly(hexafluoroethylene), EPDM rubber, and polyimide. Thus, in the embodiments of the present application, by making the insulating layer comprise at least one of the following materials: boehmite, poly(hexafluoroethylene), EPDM rubber, and polyimide, the insulation performance of the edge region of the pole piece 50 can be significantly improved, while simultaneously reducing the deposition of metal ions at the edge of the pole piece 50. This also facilitates the processing and manufacturing of the pole piece 50, thereby improving the manufacturing performance of the battery 10.

[0180] Figure 8 shows a schematic cross-sectional view of a pole piece 50 provided in another embodiment of the present application, and Figure 9 shows a schematic cross-sectional view of a pole piece 50 provided in another embodiment of the present application. For example, Figures 8 and 9 can be understood as schematic cross-sectional views of the same pole piece 50 in different directions, and Figure 8 can be a schematic cross-sectional view of the pole piece 50 in a direction perpendicular to the thickness of the pole piece 50, and Figure 9 can be a schematic cross-sectional view of the pole piece 50 in a direction perpendicular to the length of the pole piece 50. Figure 10 shows a schematic cross-sectional view of a pole piece 50 provided in another embodiment of the present application, and Figure 11 shows a schematic cross-sectional view of a pole piece 50 provided in another embodiment of the present application. For example, Figures 10 and 11 can be understood as schematic cross-sectional views of the same pole piece 50 in different directions, and Figure 10 can be a schematic cross-sectional view of the pole piece 50 in a direction perpendicular to the thickness of the pole piece 50, and Figure 11 can be a schematic cross-sectional view of the pole piece 50 in a direction perpendicular to the length of the pole piece 50.

[0181] In some embodiments, as shown in Figures 4 to 11, the edge region 530 includes a first edge region 531, which is connected to the side of the coating region 520 away from the tab region 540, and / or the edge region 530 includes a second edge region 532, which is connected between the tab region 540 and the coating region 520.

[0182] For example, as shown in Figures 8 and 9, the first body of the first current collector 510 of the pole piece 50 includes an edge region 530, which may be a first edge region 531. The first edge region 531 is connected to a side of the coating region 520 away from the tab region 540. For another example, as shown in Figures 10 and 11, the first body of the first current collector 510 of the pole piece 50 includes an edge region 530, which may be a second edge region 532. The second edge region 532 is connected between the tab region 540 and the coating region 520.

[0183] In an embodiment of the present application, the edge region 530 includes a first edge region 531, which is connected to a side of the coating region 520 away from the tab region 540, and / or the edge region 530 includes a second edge region 532, which is connected between the tab region 540 and the coating region 520. In this way, when the electrode to be cut is cut, the edge of the edge region 530 is the cutting edge, and the porosity of the second conductive layer is less than the porosity of the first conductive layer 560, that is, the density of the second conductive layer is higher than the density of the first conductive layer 560, which can effectively improve the powder falling problem at the edge region 530 during the cutting process of the electrode to be cut, thereby reducing the risk of internal short circuit in the battery cell 20 due to overlap of the positive electrode plate 502 and the negative electrode plate 501, thereby improving the yield of the battery cell 20.

[0184] The embodiment of the present application further provides a battery cell, comprising an electrode assembly 22, wherein the electrode assembly comprises the electrode piece 50 in the above embodiment. Specifically, the battery cell may be the battery cell 20 shown in FIG. 3 .

[0185] Figure 12 shows a partial cross-sectional schematic diagram of an electrode assembly 22 provided in one embodiment of the present application. As shown in Figure 12, the electrode assembly 22 includes a negative electrode sheet 501, a positive electrode sheet 502, and a separator 503, with the separator 503 disposed between the negative electrode sheet 501 and the positive electrode sheet 502. The positive electrode sheet 502 includes a positive current collector 5021 and an insulating layer 5022 disposed on at least a portion of the surface of the positive current collector 5021.

[0186] In some implementations, as shown in FIG12 , the electrode sheet 50 is a negative electrode sheet 501 , and the electrode assembly 22 further includes a positive electrode sheet 502 , wherein an insulating layer 5022 is provided at a position of the positive electrode sheet 502 corresponding to the edge region 530 of the negative electrode sheet 501 .

[0187] It should be understood that in the embodiment of the present application, the area where the insulating layer 5022 is arranged on the positive electrode plate 502 corresponding to the edge area 530 of the negative electrode plate 501 can be named as the first area, and the size of the first area along the direction Y can be less than or equal to the size of the edge area 530 on the negative electrode plate 501 along the direction Y.

[0188] In an embodiment of the present application, the electrode sheet 50 is a negative electrode sheet 501, and the electrode assembly 22 also includes a positive electrode sheet 502. An insulating layer 5022 is provided on the area of ​​the positive electrode sheet 502 corresponding to the edge area 530 of the negative electrode sheet 501. When metal ions are precipitated on the surface of the edge area 530 of the negative electrode sheet 501, the setting of the insulating layer 5022 can effectively reduce the risk of internal short circuit in the battery cell 20 due to overlap between the positive electrode sheet 502 and the negative electrode sheet 501, thereby improving the yield rate of the battery cell 20.

[0189] In some implementations, the battery cell 20 is an alkali metal battery cell. For example, the alkali metal in the alkali metal battery cell includes, but is not limited to, sodium, potassium, and lithium. Thus, in the embodiments of the present application, by configuring the battery cell 20 as an alkali metal battery cell, the energy density and reliability of the battery 10 can be improved.

[0190] The embodiment of the present application further provides a battery, comprising the battery cell 20 in the above embodiment. Specifically, the battery may be the battery 10 shown in FIG. 2 .

[0191] The present application also provides an electric device including the battery 10 of the above embodiment, wherein the battery 10 is used to provide power to the electric device. Specifically, the electric device can be the vehicle 1 shown in FIG1 , or any device using the battery 10 .

[0192] FIG13 shows a flow chart of a method for preparing a pole piece 60 to be cut provided in one embodiment of the present application. FIG14 shows a cross-sectional schematic diagram of a pole piece 60 to be cut provided in one embodiment of the present application, and FIG15 shows a cross-sectional schematic diagram of another pole piece 60 to be cut provided in another embodiment of the present application. FIG14 and FIG15 can be understood as cross-sectional schematic diagrams of the same pole piece 60 to be cut in different directions. For example, FIG14 can be a cross-sectional schematic diagram of the pole piece 60 to be cut in a direction perpendicular to the thickness of the pole piece 60 to be cut, and FIG15 can be a cross-sectional schematic diagram of the pole piece 60 to be cut in a direction perpendicular to the length of the pole piece 60 to be cut.

[0193] In some implementations, as shown in Figures 13 to 15, the method for preparing the electrode piece 50 in the embodiment of the present application includes steps 110 to 140, namely, step 110, providing a second current collector 610, wherein the second current collector 610 includes a second body and a tab forming region 630 connected to the edge of the second body, and the second body includes a coating region 520 and a cutting region 620; step 120, coating a first conductive layer 560 on the surface of the coating region 520; step 130, coating a first layer 550 on the surface of the cutting region 620; and step 140, cutting in the cutting region 620 to form the electrode piece 50 in the above embodiment, wherein the porosity of the first layer 550 is less than the porosity of the first conductive layer 560. It should be understood that in the embodiment of the present application, the order of steps 120 and 130 in the above method is not limited, that is, step 120 can be performed first and then step 130, or step 130 can be performed first and then step 120.

[0194] It should also be understood that in the embodiment of the present application, the target pole piece includes but is not limited to the pole piece 50 shown in FIG. 4 to FIG. 11 .

[0195] It should also be understood that, in some implementations, as shown in FIG14 and FIG15 , cutting within the cutting region 620 may mean that, during the slitting process of the electrode piece 60 to be cut, the cutting region 620 includes a first sub-cutting region 621, and the electrode piece 60 to be cut may be cut along a first cutting line 641, and the cutting region 620 is completely cut along the direction X, so that the electrode piece 60 to be cut is divided into two. In other implementations, cutting within the cutting region 620 may also mean that, during the die-cutting process of the electrode piece 60 to be cut, the cutting region 620 includes a second sub-cutting region 622, and the electrode piece 60 to be cut may be cut along a second cutting line 642 to form a pole ear portion at the edge of the second current collector 610.

[0196] It should also be understood that in the embodiment of the present application, the rectangular pole piece 60 to be cut shown in the above Figures 14 and 15 is only an example, and the shape of the pole piece 60 to be cut includes but is not limited to a square, a parallelogram and a polygon.

[0197] In an embodiment of the present application, the second current collector 610 includes a second body, a first conductive layer 560 is coated on the surface of the coating area 520, and a first layer 550 is coated on the surface of the cutting area 620. When cutting is performed in the cutting area 620, since the porosity of the first layer 550 is less than the porosity of the first conductive layer 560, that is, the density of the first layer 550 is higher than the density of the first conductive layer 560, the powder loss problem generated by the cutting process of the electrode 60 to be cut in the cutting area 620 can be improved by increasing the density of the first layer 550, thereby reducing the risk of internal short circuit of the battery cell 20 due to overlap of the positive electrode 502 and the negative electrode 501, thereby improving the yield of the battery cell 20.

[0198] In some implementations, as shown in Figures 16 and 17, before cutting in the cutting region 620, the method for preparing the pole piece 50 further includes: coating the surface of the area of ​​the tab forming region 630 close to the second body with the first layer 550. Thus, in the embodiment of the present application, by coating the surface of the area of ​​the tab forming region 630 close to the second body with the first layer 550, the tab forming region 630 can be strengthened to reduce deformation and cracking of the pole piece 60 to be cut during the cutting process and the subsequent winding process, thereby improving the performance of the battery 10.

[0199] In some implementations, as shown in Figures 16 and 17, before cutting in the cutting region 620, the method for preparing the pole piece 50 further includes: coating the first layer 550 on the surface of the first conductive layer 560 away from the second current collector 610. Thus, in the embodiment of the present application, by coating the first layer 550 on the surface of the first conductive layer 560 away from the second current collector 610, during the cutting process of the pole piece 60 to be cut, for example, during laser die-cutting, the thermal impact of the laser die-cutting process on the first conductive layer 560 near the cutting region 620 can be reduced, and ablation at the edge of the cutting position can be reduced, thereby improving the performance of the battery 10.

[0200] In some implementations, as shown in Figures 14 to 17, the first layer 550 includes a second conductive layer. Thus, in the embodiment of the present application, by providing the second conductive layer on the surface of the cutting area 620, the deposition area of ​​the metal ions on the target electrode piece can be increased, the conductivity of the electrode piece 50 can be improved, and the energy density of the battery 10 can be increased.

[0201] In some implementations, as shown in Figures 14 to 17, the first layer 550 includes an insulating layer. Thus, in the embodiment of the present application, by providing an insulating layer on the surface of the cutting area 620, the insulation performance of the edge region of the pole piece 50 can be improved, while effectively reducing metal deposition at the edge of the pole piece 50, thereby improving the yield rate of the battery cell 20.

[0202] In some embodiments, as shown in Figures 14 to 17, the coating area 520 includes at least two sub-coating areas, and the first sub-cutting area of ​​the cutting area 620 is arranged between the two sub-coating areas. The preparation method of the pole piece 50 also includes: cutting in the first sub-cutting area 621 to form a first edge area on the side of the coating area 520 away from the pole ear formation area 630.

[0203] For example, as shown in Figures 14 and 16, the electrode piece 60 to be cut can be cut into two target electrode pieces along the first cutting line 641 in the first sub-cutting area 621. It should be understood that the direction of the first cutting line 641 can be set according to actual needs. For example, the cutting direction of the first cutting line 641 can be parallel to the direction X, or the cutting direction of the first cutting line 641 can intersect with the direction X.

[0204] It should be understood that in an embodiment of the present application, cutting can be performed within the first sub-cutting area 621 to form a first edge area on the side of the coating area 520 away from the pole ear forming area 630, and the first edge area can be the first edge area 531 of the pole piece 50 shown in Figures 5, 7, 8 and 9 above.

[0205] In an embodiment of the present application, a first sub-cutting area 621 in the cutting area 620 is set between the two sub-coating areas, and cutting is performed in the first sub-cutting area 621 to form a first edge area 531 on the side of the coating area 520 away from the tab formation area 630. Since the porosity of the first layer 550 coated on the first sub-cutting area 621 is smaller than the porosity of the first conductive layer 560, that is, the density of the first layer 550 is higher than the density of the first conductive layer 560, the powder falling problem during the cutting process can be reduced, thereby reducing the risk of internal short circuit of the battery cell 20, and thereby improving the yield of the battery cell 20.

[0206] In some embodiments, as shown in Figures 14 and 16, the second sub-cutting area 622 in the cutting area 620 is arranged between the tab formation area 630 and the coating area 520, and the preparation method of the pole piece 50 also includes: cutting in the second sub-cutting area 622 to form the tab area 540 and the second edge area of ​​the target pole piece, and the second edge area is connected between the tab area 540 and the coating area 520.

[0207] It should be understood that in the embodiment of the present application, the tab forming area 630 is used to form the tab of the to-be-cut electrode piece 60. For example, during the die-cutting process of the to-be-cut electrode piece 60, cutting can be performed along the second cutting line 642 to form the tab. It should also be understood that in the embodiment of the present application, the number of tabs formed after die-cutting can be set according to actual needs, for example, it can be 1, 2, 3, etc. Secondly, the shape of the tab formed by die-cutting in the embodiment of the present application can be set according to actual needs, for example, the shape of the tab can be rectangular, square, trapezoidal, etc.

[0208] It should also be understood that the second edge region may be the second edge region 532 of the pole piece 50 shown in the above-mentioned Figures 5 , 7 , 10 and 11 .

[0209] In an embodiment of the present application, when the electrode 60 to be cut is subjected to a cutting process, such as a laser die-cutting process, the die-cutting position is located in the second sub-cutting area 622 between the electrode tab forming area 630 and the coating area 520. Since the porosity of the first layer 550 coated on the second sub-cutting area 622 is less than the porosity of the first conductive layer 560, that is, the density of the first layer 550 is higher than the density of the first conductive layer 560, the ablation phenomenon occurring at the die-cutting position of the cutting area 620 during the laser die-cutting process can be reduced by increasing the density of the first layer 550, and the powder falling phenomenon during the cutting process can be reduced, thereby reducing the risk of internal short circuit of the battery cell 20, and thereby improving the yield rate of the battery cell 20.

[0210] In some implementations, referring again to FIG. 10 and FIG. 11 , a pole piece 50 is provided, comprising: a first current collector 510, a first conductive layer 560, and a first layer 550. The first current collector 510 comprises a first body and a tab region 540 connected to an edge of the first body. The first body comprises a coating region 520 and an edge region 530. The first conductive layer 560 is disposed on a surface of the coating region 520, and the first layer 550 is disposed on a surface of the edge region 530. The porosity of the first layer 550 is less than that of the first conductive layer 560, and the porosity A1 of the first layer is 25%. The dimension L1 of the edge region 530 along the first direction is 5 mm. The edge region 530 comprises a second edge region 532, which is connected between the tab region 540 and the coating region 520.

[0211] Although the present application has been described with reference to the above-described embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A pole piece, characterized in that: include: A first current collector, the first current collector comprising a first body and a tab region connected to an edge of the first body, the first body comprising a coating region and an edge region; a first conductive layer, the first conductive layer being disposed on a surface of the coating area; a first layer, the first layer being disposed on a surface of the edge region; The porosity of the first layer is smaller than the porosity of the first conductive layer.

2. The pole piece according to claim 1, characterized in that: The porosity A1 of the first layer satisfies: 0%<A1≤50%.

3. The pole piece according to claim 1 or 2, characterized in that: The porosity A1 of the first layer satisfies: 20%≤A1≤30%.

4. The pole piece according to any one of claims 1 to 3, characterized in that: A ratio L1 / D1 between a dimension L1 of the edge region along a first direction and a thickness D1 of the first conductive layer satisfies: 10≤L1 / D1≤1000, preferably, 20≤L1 / D1≤100, wherein the first direction is perpendicular to the thickness direction of the pole piece.

5. The pole piece according to claim 4, characterized in that: A dimension L1 of the edge area along the first direction satisfies: 2 mm ≤ L1 ≤ 20 mm.

6. The pole piece according to claim 4 or 5, characterized in that: A dimension L1 of the edge area along the first direction satisfies: 3 mm ≤ L1 ≤ 6 mm.

7. The pole piece according to any one of claims 1 to 6, characterized in that: The thickness D1 of the first conductive layer satisfies: 1 μm≤D1≤50 μm.

8. The pole piece according to any one of claims 1 to 7, characterized in that: The material of the first conductive layer includes at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon.

9. The pole piece according to any one of claims 1 to 8, characterized in that: The first layer extends to the tab region.

10. The pole piece according to any one of claims 1 to 9, characterized in that: The first layer also extends to a surface of the first conductive layer that is away from the first current collector.

11. The pole piece according to any one of claims 1 to 10, characterized in that: The first layer includes a second conductive layer.

12. The pole piece according to claim 11, characterized in that: The material of the second conductive layer includes at least one of the following materials: carbon nanotubes, graphene, and conductive graphite.

13. The pole piece according to claim 12, characterized in that: The thickness D2 of the second conductive layer satisfies: 2 μm≤D2≤150 μm, preferably, 70 μm≤D2≤120 μm.

14. The pole piece according to claim 11, characterized in that: The material of the second conductive layer includes conductive carbon, and the thickness D2 of the second conductive layer satisfies: 10 μm≤D2≤70 μm.

15. The pole piece according to any one of claims 1 to 10, characterized in that: The first layer includes an insulating layer.

16. The pole piece according to claim 15, characterized in that: The thickness D3 of the insulating layer satisfies: 5 μm≤D3≤100 μm, preferably, 5 μm≤D3≤20 μm.

17. The pole piece according to claim 15 or 16, characterized in that: The material of the insulating layer includes at least one of the following materials: boehmite, polyvinylidene fluoride, ethylene propylene diene monomer rubber, and polyimide.

18. The pole piece according to any one of claims 1 to 17, characterized in that: The edge region includes a first edge region, the first edge region is connected to a side of the coating region away from the tab region, and / or, The edge region includes a second edge region connected between the tab region and the coating region.

19. A battery cell, characterized in that: include: An electrode assembly, comprising a pole piece as claimed in any one of claims 1 to 18.

20. The battery cell according to claim 19, characterized in that: The electrode sheet is a negative electrode sheet, and the electrode assembly further includes a positive electrode sheet. An insulating layer is provided at a position of the positive electrode sheet corresponding to an edge area of ​​the negative electrode sheet.

21. The battery cell according to claim 19 or 20, characterized in that: The battery cell is an alkali metal battery cell.

22. A battery, characterized in that: Comprising the battery cell according to any one of claims 19 to 21.

23. An electrical equipment, characterized in that: The battery comprises the battery as claimed in claim 22, wherein the battery is used to provide electrical energy to the electrical device.

24. A method for preparing a pole piece, characterized in that: include: Provide a second current collector, the second current collector comprising a second body and a second body edge connecting The second body comprises a coating area and a cutting area; Coating a first conductive layer on the surface of the coating area; Applying a first layer on the surface of the cutting area; Cutting is performed in the cutting area to form a pole piece as claimed in any one of claims 1 to 18; The porosity of the first layer is smaller than the porosity of the first conductive layer.

25. The method according to claim 24, characterized in that Before cutting in the cutting area, the method further comprises: The first layer is coated on a surface of a region of the tab forming region close to the second body.

26. The method according to claim 24 or 25, characterized in that Before cutting in the cutting area, the method further comprises: The first layer is coated on a surface of the first conductive layer away from the second current collector.

27. The method according to any one of claims 24 to 26, characterized in that The first layer includes a second conductive layer.

28. The method according to any one of claims 24 to 26, characterized in that The first layer includes an insulating layer.

29. The method according to any one of claims 24 to 28, characterized in that The coating area includes at least two sub-coating areas, a first sub-cutting area of ​​the cutting area is arranged between the two sub-coating areas, and the method further includes: cutting in the first sub-cutting area to form a first edge area on a side of the coating area away from the tab formation area.

30. The method according to any one of claims 24 to 29, characterized in that The second sub-cutting area in the cutting area is arranged between the tab forming area and the coating area, and the method further comprises: Cutting is performed in the second sub-cutting area to form a pole tab area and a second edge area of ​​the pole piece, wherein the second edge area is connected between the pole tab area and the coating area.

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