Electrode sheet, battery cell, battery, electric device, and preparation method for electrode sheet

Abstract

Provided in the embodiments of the present application are an electrode sheet, a battery cell, a battery, an electric device, and a preparation method for the electrode sheet, which can effectively ameliorate the problem of powder shedding during a cutting process of an electrode sheet to be cut, thereby reducing the risk of an internal short circuit occurring in a battery cell caused by overlapping between a positive electrode sheet and a negative electrode sheet, and thus improving the yield of the battery cell. The electrode sheet comprises: a first current collector, which comprises a first body and a tab region connected to an edge of the first body, the first body comprising a coated region and an edge region; and a first electrically conductive layer disposed on a surface of the coated region, wherein the thickness of the electrode sheet in the edge region is less than that of the electrode sheet in the coated region.

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 202310980362.0, filed on August 4, 2023, entitled “Pole piece, battery cell, battery, electrical equipment and method for preparing pole piece,” the entire contents of which are incorporated herein 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 a 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 lug 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 arranged on a surface of the coating region; wherein the thickness of the pole piece in the edge region is less than the thickness of the pole piece in the coating region.

[0009] In the embodiment of the present application, since the thickness of the electrode in the edge area is less than the thickness of the electrode in the coated area, the edge of the edge area is a cutting edge. When the electrode to be cut is cut and / or die-cut, the problem of powder loss during the cutting process of the electrode to be cut can be effectively improved, thereby reducing the risk of internal short circuit in the battery cell due to overlap of the positive electrode and the negative electrode, thereby improving the yield rate of the battery cell.

[0010] In some implementations, a dimension L1 of the edge region along a first direction satisfies: 0 mm < L1 ≤ 3 mm, and the first direction is perpendicular to a thickness direction of the pole piece.

[0011] In an embodiment of the present application, by setting the dimension L1 of the edge area along the first direction to: 0mm<L1≤3mm, and the first direction is perpendicular to the thickness direction of the electrode, the yield rate and energy density of the battery cell can be effectively taken into account, thereby improving the performance of the battery.

[0012] In some implementations, the electrode piece further includes a first layer disposed on the surface of the edge region, wherein the thickness of the first layer is less than the thickness of the first conductive layer. Thus, in the embodiments of the present application, when the electrode piece to be cut is subjected to the slitting and / or die-cutting process, the edge of the edge region serves as the cutting edge, and the thickness of the first layer is less than the thickness of the first conductive layer. This can effectively improve the problem of powder loss during the cutting process of the electrode piece to be cut, thereby reducing the risk of internal short circuits in the battery cell due to overlap of the positive electrode piece and the negative electrode piece, thereby improving the yield rate of the battery cell.

[0013] In some implementations, the thickness D1 of the first layer satisfies: 0 mm < D1 ≤ 1 mm.

[0014] In an embodiment of the present application, by setting the thickness D1 of the first layer to: 0mm<D1≤1mm, and the first layer is arranged on the surface of the edge area of ​​the electrode, the thickness of the first layer is less than the thickness of the first conductive layer, compared with the prior art, thereby reducing the risk of internal short circuit of the battery cell, thereby improving the yield rate of the battery cell.

[0015] 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 edge region, the deposition area of ​​metal ions on the electrode piece can be increased, the electrochemical performance of the battery cell can be improved, and thus the performance of the battery can be improved. At the same time, when the electrode piece to be cut is cut or die-cut, since the edge of the edge region serves as the cutting edge and the thickness of the second conductive layer is less than the thickness of the first conductive layer, the powder loss of the conductive layer during the cutting process or the ablation of the electrode piece at the cutting position after laser die-cutting can be reduced, thereby reducing the risk of internal short circuit in the battery cell and thereby improving the yield rate of the battery cell.

[0016] In some implementations, the material of the second conductive layer 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 second conductive layer to be at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon, when the electrode to be cut is cut or die-cut, since the edge of the edge region serves as the cutting edge and the thickness of the second conductive layer is less than the thickness of the first conductive layer, compared to cutting the electrode in the coated region provided with the first conductive layer, the phenomenon of powder loss of the conductive layer during the cutting process can be reduced, thereby reducing the risk of internal short circuits in the battery cells and thereby improving the yield rate of the battery cells.

[0017] In some implementations, the first layer includes an insulating layer. Thus, in the embodiments of the present application, when cutting the electrode to be cut, by providing an insulating layer on the surface of the edge region, and the thickness of the electrode in the edge region is less than the thickness of the electrode in the coated region, the problem of powder loss during the cutting process can be effectively improved, the risk of internal short circuits in the battery cells can be significantly reduced, and the yield rate of the battery cells can be improved.

[0018] In some implementations, the insulating layer comprises at least one of the following materials: boehmite, poly(hexafluoroethylene) rubber, and EPDM rubber. Thus, in the embodiments of the present application, by setting the insulating layer to be made of at least one of the following materials: boehmite, poly(hexafluoroethylene) rubber, and EPDM rubber, when the electrode to be cut is cut, the insulating layer is provided on the surface of the edge region, and the thickness of the electrode in the edge region is less than the thickness of the electrode in the coating region. This effectively reduces the problem of powder loss during the cutting process, significantly reduces the risk of internal short circuits in the battery cells, and thereby improves the yield rate of the battery cells.

[0019] In some implementations, the edge region includes a bare foil region. Thus, in the embodiments of the present application, by providing a bare foil region on the surface of the edge region, i.e., by exposing the surface of the edge region of the electrode sheet, the problem of powder loss during cutting can be effectively improved, significantly reducing the risk of internal short circuits in the battery cells, thereby improving the yield rate of the battery cells.

[0020] In some implementations, the thickness D2 of the first conductive layer satisfies the following: 2 mm ≤ D2 ≤ 20 mm. Thus, in the embodiment of the present application, by setting the thickness D2 of the first conductive layer to: 2 mm ≤ D2 ≤ 20 mm, the uniform distribution of the first conductive layer on the first current collector can be controlled, thereby balancing the energy density of the battery cell and the yield rate of the battery cell.

[0021] 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.

[0022] 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 cutting the electrode to be cut, the edge of the edge area is the cutting edge, and the thickness of the electrode in the edge area is less than the thickness of the electrode in the coating area, which can effectively improve the powder falling problem 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.

[0023] 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.

[0024] 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.

[0025] 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. An insulating layer is provided 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, the risk of internal short circuit in the battery cell due to overlap of the positive electrode sheet and the negative electrode sheet can be effectively reduced due to the provision of the insulating layer, thereby improving the yield rate of the battery cell.

[0026] In some implementations, the battery cell is an alkali metal battery cell.

[0027] In a third aspect, a battery is provided, comprising the battery cell described in any implementation of the second aspect.

[0028] In a fourth aspect, an electrical device is provided, comprising: a battery as described in any implementation of the third aspect, wherein the battery is used to provide electrical energy to the electrical device.

[0029] In some implementations, the electrical device may be a vehicle, a ship, or a spacecraft.

[0030] 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 so that the thickness of the pole piece in the cutting area is less than the thickness of the pole piece in the coating area; cutting in the cutting area to form a target pole piece; wherein the target pole piece forms an edge area in the cutting area, and the thickness of the target pole piece in the edge area is less than the thickness of the target pole piece in the coating area.

[0031] In an embodiment of the present application, by setting the thickness of the electrode to be cut in the cutting area to be smaller than the thickness of the electrode to be cut in the coated area, when cutting in the cutting area, since the thickness of the electrode to be cut in the cutting area is smaller than the thickness of the electrode to be cut in the coated area, the problem of powder falling during the cutting process can be reduced, 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.

[0032] In some embodiments, the coating area includes at least two sub-coating areas, and at least one 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.

[0033] In an embodiment of the present application, at least one first sub-cutting area of ​​the cutting area is arranged between the two sub-coating areas, and the second current collector is configured to be cut in the first sub-cutting area, that is, 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 thickness of the second current collector in the first sub-cutting area is less than the thickness of the second current collector in the sub-coating area, 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.

[0034] In some implementations, the second sub-cutting area in the cutting area is disposed between the tab forming area and the coating area, and the method further comprises: performing cutting in the second sub-cutting area to form a tab area and a second edge area of ​​the target pole piece, the second edge area being connected between the tab area and the coating area. In this way, when the second current collector is die-cut, such as by laser die-cutting, the die-cutting position is located in the second sub-cutting area between the tab forming area and the coating area. Since the thickness of the second sub-cutting area is less than that of the coating area, 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.

[0035] In some implementations, a dimension L2 of the first sub-cutting area along a first direction satisfies: 0 mm < L2 ≤ 6 mm, and the first direction is perpendicular to the thickness direction of the target electrode sheet. Thus, in this embodiment of the present application, by setting the dimension L2 of the first sub-cutting area along the first direction to: 0 mm < L2 ≤ 6 mm, both the yield rate and the energy density of the battery cells can be taken into account.

[0036] In some implementations, a dimension L3 of the second sub-cutting area along the first direction satisfies: 0 mm < L3 ≤ 3 mm, and the first direction is perpendicular to the thickness direction of the target electrode sheet. Thus, in the embodiment of the present application, by setting the dimension L3 of the second sub-cutting area along the first direction to: 0 mm < L3 ≤ 3 mm, both the yield rate and the energy density of the battery cells can be taken into account.

[0037] In some implementations, between the steps of cutting in the cutting area, the method further includes: coating a second conductive layer on the surface of the cutting area, wherein the solid content of the second conductive layer is less than that of the first conductive layer. Thus, in an embodiment of the present application, a second conductive layer is coated on the surface of the cutting area, wherein the solid content of the second conductive layer is less than that of the first conductive layer. When the second current collector is cut or die-cut, since the solid content of the second conductive layer is less than that of the first conductive layer, that is, the thickness of the second conductive layer formed after drying is less than that of the first conductive layer, compared to cutting in the coating area where the first conductive layer is provided, when cutting in the cutting area, the powdering of the conductive layer during the cutting process can be reduced, thereby reducing the risk of internal short circuit of the battery cell, and further improving the yield rate of the battery cell.

[0038] In some implementations, the solid content A1 of the second conductive layer satisfies the following range: 0% < A1 ≤ 1%. Thus, in the embodiment of the present application, by setting the solid content A1 of the second conductive layer within the range: 0% < A1 ≤ 1%, the risk of internal short circuits in the battery cells can be reduced, thereby improving the yield rate of the battery cells.

[0039] In some implementations, the second conductive layer is coated on the surface of the second current collector using a micro-gravure coating process. Thus, in the embodiments of the present application, the second conductive layer is coated on the surface of the second current collector using a micro-gravure coating process, which can achieve uniform coating of the second current collector and improve the adhesion between the second conductive layer and the surface of the second current collector, thereby effectively reducing the problem of powder loss during cutting, reducing the risk of internal short circuits in battery cells, and thereby improving the yield rate of battery cells.

[0040] In some implementations, the solid content A2 of the first conductive layer satisfies the following: 1.5% ≤ A2 ≤ 10%. Thus, in the embodiment of the present application, by setting the solid content A2 of the first conductive layer to the following: 1.5% ≤ A2 ≤ 10%, the deposition of metal ions in the coating area of ​​the electrode can be improved, thereby increasing the energy density of the battery cell.

[0041] In some implementations, before the step of cutting within the cutting region, the method further includes: providing an insulating layer on the surface of the cutting region. Thus, in the embodiment of the present application, when the second current collector is cut, by providing an insulating layer on the surface of the cutting region, and the thickness of the second current collector in the cutting region is less than the thickness of the second current collector in the coating region, the problem of powder loss during the cutting process can be effectively improved, the risk of internal short circuits in the battery cells can be significantly reduced, and the yield rate of the battery cells can be improved.

[0042] In some implementations, the cutting area includes a bare foil area. Thus, in the embodiments of the present application, by providing a bare foil area on the surface of the cutting area, i.e., by exposing the surface of the cutting area of ​​the second current collector, the problem of powder loss during the cutting process can be effectively improved, significantly reducing the risk of internal short circuits in the battery cells, thereby improving the yield rate of the battery cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] 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.

[0044] FIG1 is a schematic structural diagram of a vehicle provided in one embodiment of the present application.

[0045] FIG2 is a schematic structural diagram of a battery provided in one embodiment of the present application.

[0046] FIG3 is a schematic structural diagram of a battery cell provided in one embodiment of the present application.

[0047] FIG4 is a schematic cross-sectional view of a pole piece provided in one embodiment of the present application.

[0048] FIG5 is a schematic cross-sectional view of a pole piece provided in another embodiment of the present application.

[0049] FIG6 is a schematic cross-sectional view of a pole piece provided in yet another embodiment of the present application.

[0050] FIG7 is a schematic cross-sectional view of a pole piece provided in yet another embodiment of the present application.

[0051] FIG8 is a schematic cross-sectional view of a pole piece provided in yet another embodiment of the present application.

[0052] FIG9 is a schematic cross-sectional view of a pole piece provided in yet another embodiment of the present application.

[0053] FIG10 is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0054] FIG11 is a schematic cross-sectional view of a pole piece provided in another embodiment of the present application.

[0055] FIG12 is a partial cross-sectional schematic diagram of an electrode assembly provided in another embodiment of the present application.

[0056] FIG13 is a schematic flow chart of a method for preparing a pole piece provided in one embodiment of the present application.

[0057] FIG14 is a schematic cross-sectional view of a pole piece to be cut provided in one embodiment of the present application.

[0058] FIG15 is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0059] FIG16 is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0060] FIG17 is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0061] FIG18 is a schematic cross-sectional view of a pole piece to be cut provided in another embodiment of the present application.

[0062] FIG19 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 detailed description of the following 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 of 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] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. In some implementations, other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4, also referred to as LFP), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0085] As an example, the positive electrode active material may include at least one of a sodium transition metal oxide, a polyanionic compound, and a Prussian blue-based compound:

[0086] In some implementations, the chemical formula of the sodium transition metal oxide may satisfy NaxMO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr, and Cu, and 0<x≤1. As an example, x in NaxMO2 may be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0087] In some implementations, the sodium transition metal oxide may be a sodium transition metal oxide that has been doped and modified, and the doping modification of the sodium transition metal oxide may include at least one of sodium site doping modification, oxygen site doping modification, transition metal site doping modification, and surface coating modification.

[0088] 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.

[0089] In some implementations, the negative electrode may be a negative electrode plate, and the negative electrode plate may include a negative electrode current collector.

[0090] 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.).

[0091] In some implementations, the battery cells in the embodiments of the present application may be negative electrode metal-free batteries.

[0092] In some implementations, the battery cell in the embodiments of the present application may be a negative electrode-free sodium secondary battery.

[0093] 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.

[0094] 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.

[0095] In some implementations, the CB value of the negative electrode-free sodium secondary battery is less than or equal to 0.1.

[0096] Specifically, the CB value is the capacity per unit area of ​​the negative electrode in a secondary battery divided by the capacity per unit area of ​​the positive electrode. Since a battery without a negative electrode contains no or only a small amount of functional coating, the capacity per unit area of ​​the negative electrode is relatively small, and the CB value of the secondary battery is less than or equal to 0.1.

[0097] 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.

[0098] In some implementations, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0107] 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.

[0108] 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.

[0109] In some implementations, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0110] 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.

[0111] 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.

[0112] As an example, the battery cells may be cylindrical, prismatic, soft-pack or other shaped battery cells. Prismatic battery cells include square-shell, blade-shaped, and polygonal batteries. Polygonal batteries may be, for example, hexagonal batteries.

[0113] 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.

[0114] 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.

[0115] In order to meet different power requirements, the battery in the embodiment of the present application may include multiple battery cells, wherein the multiple battery cells can be connected in series, in parallel, or in hybrid connection, and hybrid connection refers to a mixture of series and parallel connection. Optionally, multiple battery cells can first be connected in series, in parallel, or in hybrid connection to form a battery module, and multiple battery modules can then be connected in series, in parallel, or in hybrid connection to form a battery. In other words, multiple battery cells can directly form a battery, or they can first form a battery module, and the battery module can then form a battery. The battery is further arranged in an electrical device to provide electrical energy to the electrical device.

[0116] Currently, the design of the pole pieces in battery cells is crucial to their yield and performance. Alkali metal batteries in this field typically lack a negative electrode, meaning the negative electrode is coated with only a thin conductive coating. Due to the thinness of the pole pieces, existing cold-pressing equipment struggles to fully compress them, resulting in poor adhesion between the conductive coating and the current collector. This can lead to powder loss or ablation in the cut areas during subsequent slitting and die-cutting processes, creating dust and burrs. This can lead to overlapping of the positive and negative pole pieces, creating the risk of a short circuit within the battery cell and impacting the yield of the battery cell.

[0117] Specifically, in the battery manufacturing process, slitting refers to cutting the electrode sheet to be cut into narrow strips along its length. This is usually achieved using dedicated equipment and tools, such as slitting machines and cutting knives. Slitting can cut the electrode sheet into strips of different widths as required to meet different application needs. Die-cutting refers to the process of passing the electrode sheet to be cut through a forming die or laser shearing to form a specific shape and specification of the electrode tab on the electrode sheet to be cut. It should be understood that in the manufacturing process of the electrode sheet, the slitting process and the die-cutting process can be carried out simultaneously or one after another.

[0118] In view of this, an embodiment of the present application provides a pole piece, comprising: a first current collector and a first conductive layer, 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, the first conductive layer being arranged on the surface of the coating region, wherein the thickness of the pole piece in the edge region is less than the thickness of the pole piece in the coating region. In an embodiment of the present application, when the pole piece to be cut is cut and / or die-cut, the edge of the edge region is the cutting edge, and the thickness of the pole piece in the edge region is less than the thickness of the pole piece in the coating region, which can effectively improve the powder loss problem of the pole piece to be cut during the cutting process, 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.

[0119] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use batteries.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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 .

[0131] 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.

[0132] 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.

[0133] Figure 4 shows a cross-sectional schematic diagram of a pole piece 50 provided in one embodiment of the present application, and Figure 5 shows a cross-sectional schematic diagram of a pole piece 50 provided in another embodiment of the present application, wherein Figures 4 and 5 can be understood as cross-sectional schematic diagrams of the same pole piece 50 in different directions. For example, Figure 4 can be a cross-sectional schematic diagram of the pole piece 50 perpendicular to the thickness direction of the pole piece 50, and Figure 5 can be a cross-sectional schematic diagram of the pole piece 50 perpendicular to the length direction of the pole piece 50.

[0134] It should be understood that in the embodiments of the present application, for the convenience of description, as shown in Figures 4 and 5, direction X may be the length direction of the pole piece 50, and the direction X is perpendicular to direction Y and direction Z; direction Y may be the width direction of the pole piece 50, and the direction Y is perpendicular to direction X and direction Z; direction Z may be the height direction of the pole piece 50, and the direction Z is perpendicular to direction X and direction Y, and the direction Z may also refer to the thickness direction of the pole piece 50.

[0135] In some embodiments, as shown in Figures 4 and 5, the pole piece 50 includes: a first current collector 510 and a first conductive layer 580, 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, and the first conductive layer 580 is arranged on the surface of the coating area 520; wherein, the thickness H1 of the pole piece 50 in the edge area 530 is less than the thickness H2 of the pole piece 50 in the coating area 520.

[0136] It should be understood that in the embodiment of the present application, the first conductive layer 580 is arranged on the surface of the coating area 520, which may mean that the first conductive layer 580 can be arranged on at least one of the two surfaces of the coating area 520 in the thickness direction perpendicular to the coating area 520.

[0137] It should also be understood that in the embodiment of the present application, the rectangular pole piece 50 shown in FIG. 4 and FIG. 5 is only an example, and the shape of the pole piece 50 includes but is not limited to a rectangle, a square, a parallelogram, and a polygon.

[0138] 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.

[0139] 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.

[0140] It should also be understood that in the embodiment of the present application, the thickness H1 of the pole piece 50 in the edge area 530 is less than the thickness H2 of the pole piece 50 in the coating area 520, which may mean that the average thickness H1 of the pole piece 50 in the edge area 530 is less than the average thickness H2 of the pole piece 50 in the coating area 520, or it may mean that the maximum thickness H1 of the pole piece 50 in the edge area 530 is less than the maximum thickness H2 of the pole piece 50 in the coating area 520.

[0141] In the embodiment of the present application, since the thickness H1 of the electrode 50 in the edge area 530 is less than the thickness H2 of the electrode 50 in the coated area 520, the edge of the edge area 530 is a cutting edge. When the electrode to be cut is cut and / or die-cut, the problem of powder loss during the cutting process of the electrode to be cut can be effectively improved, thereby reducing the risk of internal short circuit in 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.

[0142] 4 and 5 , the dimension L1 of the edge region 530 along the first direction satisfies: 0 mm < L1 ≤ 3 mm, and the first direction is perpendicular to the thickness direction of the pole piece 50. For example, in the embodiment of the present application, the first direction may be direction Y or direction X.

[0143] It should be understood that in the embodiment of the present application, as shown in Figures 4 and 5, 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.

[0144] For example, the dimension L1 of the edge region 530 along the first direction in the embodiment of the present application may be: 0.1mm, 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3.0mm, or any value within the range obtained by combining any two of the above values. In other implementations, the dimension L1 of the edge region 530 along the first direction in the embodiment of the present application may be: 0.5mm≤L1≤1mm.

[0145] In the embodiment of the present application, by setting the dimension L1 of the edge area 530 along the first direction to: 0mm<L1≤3mm, and the first direction is perpendicular to the thickness direction of the electrode 50, the yield rate of the battery cell 20 and the energy density of the battery cell 20 can be taken into account, thereby improving the performance of the battery 10.

[0146] In some implementations, as shown in Figures 4 and 5, the pole piece 50 further includes a first layer 550 disposed on the surface of the edge region 530, and the thickness D1 of the first layer 550 is less than the thickness D2 of the first conductive layer 580. It should be understood that in the embodiment of the present application, the pole piece 50 further includes the first layer 550 disposed on the surface of the edge region 530, which may mean that the first layer 550 can 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.

[0147] It should be understood that in the embodiment of the present application, the thickness D1 of the first layer 550 is less than the thickness D2 of the first conductive layer 580 , which means that the average thickness D1 of the first layer 550 is less than the average thickness D2 of the first conductive layer 580 .

[0148] Thus, in the embodiment of the present application, when the electrode to be cut is subjected to the slitting and / or die-cutting process, since the edge of the edge region 530 is the cutting edge and the thickness D1 of the first layer 550 is less than the thickness D2 of the first conductive layer 580, the problem of powder loss during the cutting process of the electrode to be cut can be effectively improved, thereby reducing the risk of internal short circuit of the battery cell 20 due to overlap of the positive electrode sheet 502 and the negative electrode sheet 501, thereby improving the yield rate of the battery cell 20.

[0149] In some implementations, as shown in FIG5 , the thickness D1 of the first layer 550 satisfies: 0 mm < D1 ≤ 1 mm.

[0150] For example, the thickness D1 of the first layer 550 in the embodiment of the present application may be: 0.05mm, 0.1mm, 0.15mm, 0.20mm, 0.25mm, 0.30mm, 0.35mm, 0.40mm, 0.45mm, 0.50mm, 0.55mm, 0.60mm, 0.65mm, 0.70mm, 0.75mm, 0.80mm, 0.85mm, 0.90mm, 0.95mm, 1mm, or any value within the range obtained by combining any two of the above values. In other implementations, the thickness D1 of the first layer 550 in the embodiment of the present application may be: 0.25mm≤D1≤0.75mm.

[0151] In an embodiment of the present application, by setting the thickness D1 of the first layer 550 to: 0mm<D1≤1mm, and the first layer 550 is arranged on the surface of the edge area 530 of the pole piece 50, the thickness D1 of the first layer 550 is less than the thickness D2 of the first conductive layer 580. Compared with the prior art, the risk of internal short circuit of the battery cell 20 can be reduced, thereby improving the yield rate of the battery cell 20.

[0152] In some implementations, as shown in FIG. 4 and FIG. 5 , the first layer 550 includes a second conductive layer 560 .

[0153] It should be understood that in the embodiment of the present application, the thickness of the second conductive layer 560 is less than the thickness of the first conductive layer 580, and the second conductive layer 560 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.

[0154] Thus, in the embodiment of the present application, by setting the second conductive layer 560 on the surface of the edge region 530, the deposition area of ​​the metal ions on the electrode 50 can be increased, the electrochemical performance of the battery cell 20 can be improved, and thus the performance of the battery 10 can be improved. At the same time, when the electrode to be cut is cut or die-cut, since the edge of the edge region 530 is the cutting edge and the thickness of the second conductive layer 560 is less than the thickness of the first conductive layer 580, the powder loss of the conductive layer during the cutting process or the ablation of the electrode 50 at the cutting position after die-cutting 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.

[0155] In some implementations, the material of the second 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 second conductive layer 560 to be at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon, when the electrode to be cut is cut or die-cut, since the edge of the edge region 530 serves as the cutting edge and the thickness of the second conductive layer 560 is less than the thickness of the first conductive layer 580, compared to cutting the electrode in the coating region 520 provided with the first conductive layer 580, the powder loss of the conductive layer during the cutting process can be reduced, thereby reducing the risk of internal short circuits in the battery cell 20 and thereby improving the yield rate of the battery cell 20.

[0156] In some implementations, as shown in FIG. 4 and FIG. 5 , the first layer 550 includes an insulating layer 570 .

[0157] It should be understood that in the embodiment of the present application, the thickness of the insulating layer 570 is less than the thickness of the first conductive layer 580, and the insulating layer 570 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.

[0158] Thus, in the embodiment of the present application, when the electrode to be cut is cut or die-cut, by setting an insulating layer 570 on the surface of the edge area 530, and the thickness H1 of the electrode 50 in the edge area 530 is less than the thickness H2 of the electrode 50 in the coating area 520, the powder falling problem during the cutting process can be effectively improved, and the risk of internal short circuit of the battery cell 20 can be significantly reduced, thereby improving the yield of the battery cell 20.

[0159] In some implementations, the insulating layer 570 is made of at least one of the following materials: boehmite, poly(hexafluoroethylene) rubber, and EPDM rubber. Thus, in the embodiment of the present application, by making the insulating layer 570 of at least one of the following materials: boehmite, poly(hexafluoroethylene) rubber, and EPDM rubber, when the electrode to be cut is cut, the insulating layer 570 is provided on the surface of the edge region 530 , and the thickness H1 of the electrode 50 in the edge region 530 is less than the thickness H2 of the electrode 50 in the coating region 520 . This effectively reduces the problem of powder loss during the cutting process, significantly reduces the risk of internal short circuits in the battery cells 20, and thereby improves the yield rate of the battery cells 20.

[0160] 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. For example, FIG6 and FIG7 can be understood as schematic cross-sectional views of the same pole piece 50 in different directions. 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.

[0161] In some implementations, as shown in Figures 6 and 7, the edge region 530 includes a hollow foil region. Thus, in the embodiments of the present application, by providing a hollow foil region on the surface of the edge region 530, i.e., by exposing the surface of the edge region 530 of the electrode 50, the problem of powder loss during the cutting process can be effectively improved, and the risk of internal short circuits in the battery cells 20 can be significantly reduced, thereby improving the yield rate of the battery cells 20.

[0162] In some implementations, as shown in FIG. 4 to FIG. 7 , the thickness D2 of the first conductive layer 580 satisfies: 2 mm ≤ D2 ≤ 20 mm.

[0163] For example, the thickness D2 of the first conductive layer 580 may be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, or 20 mm, or any value within the range obtained by combining any two of the above values. In other implementations, the thickness D2 of the first conductive layer 580 in the embodiment of the present application may also be 4 mm ≤ D2 ≤ 10 mm.

[0164] Thus, in the embodiment of the present application, by setting the thickness D2 of the first conductive layer 580 to: 2 mm ≤ D2 ≤ 20 mm, the uniform distribution of the first conductive layer 580 on the first current collector 510 can be controlled to take into account both the energy density of the battery cell 20 and the yield rate of the battery cell 20.

[0165] 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 perpendicular to the thickness direction of the pole piece 50, and Figure 9 can be a schematic cross-sectional view of the pole piece 50 perpendicular to the length direction 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 perpendicular to the thickness direction of the pole piece 50, and Figure 11 can be a schematic cross-sectional view of the pole piece 50 perpendicular to the length direction of the pole piece 50.

[0166] 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.

[0167] 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.

[0168] In an embodiment of the present application, the edge region 530 includes a first edge region 531 and / or a second edge region 532, the first edge region 531 being connected to the side of the coating region 520 away from the tab region 540, and the second edge region 532 being 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 thickness H1 of the electrode 50 in the edge region 530 is less than the thickness H2 of the electrode 50 in the coating region 520, which can effectively improve the powder loss problem of the electrode to be cut during the cutting process, 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.

[0169] 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 .

[0170] Figure 12 shows a partial cross-sectional view 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, wherein the separator 503 is disposed between the negative electrode sheet 501 and the positive electrode sheet 502.

[0171] 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 . An insulating layer 570 is provided at an area of ​​the positive electrode sheet 502 corresponding to an edge area of ​​the negative electrode sheet 501 .

[0172] It should be understood that in the embodiment of the present application, the area where the insulating layer 570 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.

[0173] 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 570 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 570 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 of the battery cell 20.

[0174] In some implementations, the battery cell 20 is an alkali metal battery cell.

[0175] The present application also provides a battery, including the battery cell 20 in the above embodiment. Specifically, the battery may be the battery 10 shown in FIG. 2 .

[0176] 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 .

[0177] FIG13 shows a flow chart 100 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, FIG15 shows a cross-sectional schematic diagram of another pole piece 60 to be cut provided in another embodiment of the present application, FIG16 shows a cross-sectional schematic diagram of another pole piece 60 to be cut provided in another embodiment of the present application, and FIG17 shows a cross-sectional schematic diagram of another pole piece 60 to be cut provided in another embodiment of the present application. Among them, 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 perpendicular to the thickness direction 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 perpendicular to the length direction of the pole piece 60 to be cut. For example, Figures 16 and 17 can be understood as cross-sectional schematic diagrams of the same pole piece 60 to be cut in different directions. Figure 16 can be a cross-sectional schematic diagram of the pole piece 60 to be cut perpendicular to the thickness direction of the pole piece 60 to be cut, and Figure 17 can be a cross-sectional schematic diagram of the pole piece 60 to be cut perpendicular to the length direction of the pole piece 60 to be cut.

[0178] In some implementations, as shown in Figures 13 to 17, the method for preparing the pole piece 50 in the embodiment of the present application includes steps 110 to 130, namely, 110, providing a second current collector 610, the second current collector 610 including a second body and a pole ear forming area 630 connected to the edge of the second body, the second body including a coating area 520 and a cutting area 620; 120, coating a first conductive layer 580 on the surface of the coating area 520, so that the thickness H3 of the pole piece 60 to be cut in the cutting area 620 is less than the thickness H4 of the pole piece 60 to be cut in the coating area 520. 130, cutting is performed in the cutting area 620 to form a target pole piece, wherein the target pole piece forms an edge area 530 in the cutting area 620, and the thickness of the target pole piece in the edge area 530 is less than the thickness of the target pole piece in the coating area 520.

[0179] It should 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 Figures 4 to 12 above.

[0180] It should also be understood that in the embodiment of the present application, the thickness of the target electrode in the edge region 530 may be the thickness H1 of the electrode 50 in the edge region 530 shown in Figures 4 to 12 above. The thickness of the target electrode in the coating region 520 may be the thickness H2 of the electrode 50 in the coating region 520 shown in Figures 4 to 12 above.

[0181] It should also be understood that in the embodiment of the present application, the thickness H3 of the pole piece 60 to be cut in the cutting area 620 is less than the thickness H4 of the pole piece 60 to be cut in the coating area 520, which may mean that the average thickness H3 of the pole piece 60 to be cut in the cutting area 620 is less than the average thickness H4 of the pole piece 60 to be cut in the coating area 520, or the maximum thickness H3 of the pole piece 60 to be cut in the cutting area 620 is less than the maximum thickness H4 of the pole piece 60 to be cut in the coating area 520.

[0182] It should also be understood that, in some implementations, as shown in FIG14 and FIG16 , 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. 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 510.

[0183] 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 to 17 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.

[0184] In an embodiment of the present application, by setting the thickness H3 of the electrode piece 60 to be cut in the cutting area 620 to be smaller than the thickness H4 of the electrode piece 60 to be cut in the coating area 520, when cutting is performed in the cutting area 620, since the thickness H3 of the electrode piece 60 to be cut in the cutting area 620 is smaller than the thickness H4 of the electrode piece 60 to be cut in the coating area 520, the problem of powder falling during the cutting process can be reduced, thereby reducing the risk of internal short circuit in the battery cell 20 due to overlap of the positive electrode piece 502 and the negative electrode piece 501, thereby improving the yield rate of the battery cell 20.

[0185] In some embodiments, as shown in Figures 14 to 17, the coating area 520 includes at least two sub-coating areas, and at least one first sub-cutting area 621 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 531 on the side of the coating area 520 away from the pole ear formation area 630.

[0186] 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.

[0187] 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 531 on the side of the coating area 520 away from the pole ear forming area 630, and the first edge area 531 can be the first edge area 531 of the pole piece 50 shown in Figures 4 to 12 above.

[0188] In an embodiment of the present application, at least one first sub-cutting area 621 of the cutting area 620 is set between the two sub-coating areas, and the second current collector 610 is configured to be cut in the first sub-cutting area 621, that is, cutting is performed within 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 thickness of the second current collector 610 in the first sub-cutting area 621 is less than the thickness of the second current collector 610 in the sub-coating area, 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.

[0189] In some embodiments, as shown in Figures 14 to 17, the second sub-cutting area 622 in the cutting area 620 is arranged between the pole 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 pole tab area 540 and the second edge area 532 of the target pole piece, and the second edge area 532 is connected between the pole tab area 540 and the coating area 520.

[0190] 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.

[0191] In an embodiment of the present application, when the second current collector 610 is die-cut, such as laser die-cutting, the die-cutting position is located in the second sub-cutting area 622 between the tab formation area 630 and the coating area 520. Since the thickness of the second current collector 610 in the second sub-cutting area 622 is less than the thickness of the second current collector 610 in the coating area 520, the ablation phenomenon occurring at the die-cutting position of the cutting area 620 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 20, and thereby improving the yield rate of the battery cell 20.

[0192] In some implementations, as shown in FIG. 14 to FIG. 17 , a dimension L2 of the first sub-cutting area 621 along a first direction satisfies: 0 mm < L2 ≤ 6 mm, and the first direction is perpendicular to the thickness direction of the target pole piece.

[0193] For example, the dimension L2 of the first sub-cutting area 621 along the first direction may be: 0.1mm, 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, or any value within the range obtained by combining any two of the above values. In other implementations, the dimension L2 of the first sub-cutting area 621 along the first direction may also be: 1mm≤L2≤2mm.

[0194] Thus, in the embodiment of the present application, by setting the dimension L2 of the first sub-cutting area 621 along the first direction to: 0 mm < L2 ≤ 6 mm, the yield rate of the battery cell 20 and the energy density of the battery cell 20 can be taken into account at the same time.

[0195] In some implementations, as shown in FIG. 13 to FIG. 17 , the dimension L3 of the second sub-cutting area 622 along the first direction satisfies: 0 mm < L3 ≤ 3 mm, and the first direction is perpendicular to the thickness direction of the target pole piece.

[0196] For example, the dimension L3 of the second sub-cutting area 622 along the first direction may be: 0.1mm, 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3.0mm, or its value is within the range obtained by combining any two of the above values. In other implementations, the dimension L3 of the second sub-cutting area 622 along the first direction in the embodiment of the present application may also be: 0.5mm≤L3≤1mm.

[0197] Thus, in the embodiment of the present application, by setting the dimension L3 of the second sub-cutting area 612 along the first direction to: 0 mm < L3 ≤ 3 mm, the yield rate of the battery cell 20 and the energy density of the battery cell 20 can be taken into account at the same time.

[0198] In some embodiments, as shown in Figures 14 and 15, between the steps of cutting in the cutting area 620, the method also includes: coating a second conductive layer 560 on the surface of the cutting area 620, and the solid content A1 of the second conductive layer 560 is less than the solid content A2 of the first conductive layer 580.

[0199] It should be understood that in the embodiment of the present application, the thickness D1 of the second conductive layer 560 is less than the thickness D2 of the first conductive layer 580, and the second conductive layer 560 can be arranged on at least one of the two surfaces of the cutting area 620 perpendicular to the thickness direction of the cutting area 620.

[0200] Thus, in the embodiment of the present application, the second conductive layer 560 is coated on the surface of the cutting area 620, and the solid content A1 of the second conductive layer 560 is less than the solid content A2 of the first conductive layer 580. When the second current collector 610 is cut or die-cut, since the solid content A1 of the second conductive layer 560 is less than the solid content A2 of the first conductive layer 580, that is, the thickness D1 of the second conductive layer formed after drying is less than the thickness D2 of the first conductive layer, compared with cutting in the coating area 520 provided with the first conductive layer 580, when cutting in the cutting area 620, the powder falling phenomenon of the conductive layer 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.

[0201] In some implementations, the solid content A1 of the second conductive layer 560 satisfies: 0%<A1≤1%.

[0202] It should be understood that the solid content in the present embodiment refers to the percentage of the mass of the slurry remaining after drying under specified conditions for coating the surface of the second current collector 610. For example, in the present embodiment, a coating slurry with a solid content of 0.5% is formed by mixing a conductive carbon material and carboxymethyl cellulose in a specific ratio. This slurry is then evenly coated on the surface of the edge region 530 of the electrode 50 and subjected to drying, compaction, and other processes to form the second conductive layer 560.

[0203] For example, the solid content A1 of the second conductive layer 560 in the embodiment of the present application may be: 0.01%, 0.03%, 0.05%, 0.07%, 0.09%, 0.1%, 0.2%, 0.25%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.75%, 0.8%, 0.9%, 1%, or any value within the range obtained by combining any two of the above values. In other implementations, the solid content A1 of the second conductive layer 560 in the embodiment of the present application may be: 0.25%<A1≤0.75%.

[0204] Thus, in the embodiment of the present application, by setting the solid content A1 of the second conductive layer 560 to be in the range of 0%<A1≤1%, the risk of internal short circuit of the battery cell 20 can be reduced, thereby improving the yield of the battery cell 20.

[0205] In some implementations, the second conductive layer 560 is coated on the surface of the second current collector 610 by a micro-gravure coating process.

[0206] It should be understood that when coating the second current collector 610 in the embodiment of the present application, a gravure coating process is generally used. A back roller is provided in the gravure coating process. The function of the back roller is to better contact the second current collector 610 with the gravure roller, so that more coating liquid is transferred to the surface of the second current collector 610. However, due to the large pressure generated by the back roller, wrinkles may be generated in the coating on the surface of the second current collector 610, resulting in uneven coating and affecting the yield of the battery cell 20. The micro-gravure coating process in the embodiment of the present application uses a gravure roller. The surface of the gravure roller is mounted on a bearing and partially immersed in the feed tray. The coating is picked up by a rotating shaft, and after being quantitatively measured by a flexible scraper, the coating liquid is taken away by the second current collector 610 moving in the opposite direction. That is, the micro-gravure coating process adopts a kiss coating method. The rotation direction of the gravure roller in the micro-gravure coating process is opposite to the movement direction of the second current collector 610. There is no need for a back roller to press the second current collector 610 onto the gravure roller. A very thin coating can be applied to the surface of the second current collector 610, and a uniform thin layer coating can be achieved.

[0207] In an embodiment of the present application, the second conductive layer 560 is coated on the surface of the second current collector 610 through a micro-gravure coating process, which can achieve uniform coating of the second current collector 610 and improve the adhesion between the surface of the second current collector 610 and the second conductive layer 560, thereby effectively reducing the powder loss problem during the cutting process, reducing the risk of internal short circuit of the battery cell 20, and thereby improving the yield rate of the battery cell 20.

[0208] In some implementations, as shown in FIG. 14 to FIG. 17 , the solid content A2 of the first conductive layer 580 satisfies: 1.5%≤A2≤10%.

[0209] For example, the solid content A2 of the first conductive layer 580 in the embodiment of the present application may be: 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or any value within the range obtained by combining any two of the above values. In other implementations, the solid content A2 of the first conductive layer 580 in the embodiment of the present application may be: 2% ≤ A2 ≤ 5%.

[0210] Thus, in the embodiment of the present application, by setting the solid content A2 of the first conductive layer 580 to: 1.5%≤A2≤10%, the deposition amount of metal ions in the coating area of ​​the electrode can be improved, thereby increasing the energy density of the battery cell 20.

[0211] In some implementations, as shown in FIG. 14 and FIG. 15 , before the step of cutting in the cutting area 620 , the method for preparing the pole piece 50 further includes: disposing an insulating layer 570 on the surface of the cutting area 620 .

[0212] It should be understood that in the embodiment of the present application, the thickness of the insulating layer 570 is less than the thickness of the first conductive layer 580, and the insulating layer 570 can be arranged on at least one of the two surfaces of the cutting area 620 in a thickness direction perpendicular to the cutting area 620.

[0213] Thus, in the embodiment of the present application, when the second current collector 610 is cut, by setting an insulating layer 570 on the surface of the cutting area 620, and the thickness H3 of the second current collector 610 in the cutting area 620 is less than the thickness H4 of the second current collector 610 in the coating area 520, the powder falling problem during the cutting process can be effectively improved, and the risk of internal short circuit of the battery cell 20 can be significantly reduced, thereby improving the yield of the battery cell 20.

[0214] In some implementations, as shown in Figures 16 and 17 , the cutting region 620 includes a hollow foil region. Thus, in the embodiment of the present application, by providing a hollow foil region on the surface of the cutting region 620 , i.e., by exposing the surface of the cutting region 620 of the second current collector 610 to a bare surface, the problem of powder loss during the cutting process can be effectively improved, significantly reducing the risk of internal short circuits in the battery cells 20 , and thereby improving the yield rate of the battery cells 20 .

[0215] FIG18 is a schematic cross-sectional view of a pole piece 60 to be cut according to another embodiment of the present application, and FIG19 is a schematic cross-sectional view of a pole piece 60 to be cut according to another embodiment of the present application. FIG18 and FIG19 can be understood as schematic cross-sectional views of the same pole piece 60 to be cut in different directions. For example, FIG18 can be a schematic cross-sectional view of the pole piece 60 to be cut perpendicular to the thickness direction of the pole piece 60 to be cut, and FIG19 can be a schematic cross-sectional view of the pole piece 60 to be cut perpendicular to the length direction of the pole piece 60 to be cut.

[0216] In some implementations, as shown in FIG18 and FIG19 , a pole piece 60 to be cut is provided. The pole piece 60 to be cut includes a second current collector 610. The second current collector 610 includes a tab formation region 630, a coating region 520, and a second sub-cut region 622. The second sub-cut region 622 is disposed between the tab formation region 630 and the coating region 520. A first conductive layer 580 is coated on the surface of the coating region 520. The thickness D2 of the first conductive layer 580 is 5 mm. A second conductive layer 560 is coated on the surface of the second sub-cut region 622 by a micro-gravure coating process. The thickness D1 of the second conductive layer 560 is 0.5 mm. The dimension L3 of the second sub-cut region 622 along the width direction of the pole piece 60 to be cut is 2 mm. When cutting the pole piece 60 to be cut, cutting can be performed along a second cutting line 642 within the second sub-cut region 622 to form a target pole piece.

[0217] In some implementations, referring again to FIG. 4 and FIG. 5 , a pole piece 50 is provided, comprising: a first current collector 510 and a first conductive layer 580. 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 580 is disposed on a surface of the coating region 520. The thickness of the pole piece 50 in the edge region 530 is less than the thickness of the pole piece 50 in the coating region 520. The edge region 530 comprises a first edge region 531 and a second edge region 532. The first edge region 531 is connected to a side of the coating region 520 away from the tab region 540, and the second edge region 532 is connected between the tab region 540 and the coating region 520. The edge region 530 of the pole piece 50 is a hollow foil region, i.e., the surface of the edge region 530 of the pole piece 50 is exposed. The dimension of the first edge region 531 along the width direction of the pole piece 50 is 2 mm, and the dimension of the second edge region 532 along the width direction of the pole piece 50 is 2.5 mm.

[0218] 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; Wherein, the thickness of the pole piece in the edge region is smaller than the thickness of the pole piece in the coating region.

2. The pole piece according to claim 1, characterized in that: A dimension L1 of the edge region along a first direction satisfies: 0 mm<L1≤3 mm, and the first direction is perpendicular to a thickness direction of the pole piece.

3. The pole piece according to claim 1 or 2, characterized in that: The pole piece further includes a first layer disposed on the surface of the edge region, and a thickness of the first layer is smaller than a thickness of the first conductive layer.

4. The pole piece according to claim 3, characterized in that: The thickness D1 of the first layer satisfies: 0 mm<D1≤1 mm.

5. The pole piece according to claim 3 or 4, characterized in that: The first layer includes a second conductive layer.

6. The pole piece according to claim 5, characterized in that: The material of the second conductive layer includes at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon.

7. The pole piece according to claim 3 or 4, characterized in that: The first layer includes an insulating layer.

8. The pole piece according to claim 7, characterized in that: The material of the insulating layer includes at least one of the following materials: boehmite, polyvinylidene fluoride, and ethylene propylene diene monomer rubber.

9. The pole piece according to claim 1 or 2, characterized in that: The edge region comprises a hollow foil region.

10. The pole piece according to any one of claims 1 to 9, characterized in that: The thickness D2 of the first conductive layer satisfies: 2 mm ≤ D2 ≤ 20 mm.

11. The pole piece according to any one of claims 1 to 10, 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.

12. A battery cell, characterized in that: include: An electrode assembly, comprising a pole piece as claimed in any one of claims 1 to 11.

13. The battery cell according to claim 12, 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.

14. The battery cell according to claim 12 or 13, characterized in that: The battery cell is an alkali metal battery cell.

15. A battery, characterized in that: The method comprises a battery cell as claimed in any one of claims 12 to 14.

16. An electrical equipment, characterized in that: The battery as claimed in claim 15 is used to provide electrical energy to the electrical device.

17. A method for preparing a pole piece, characterized in that: include: Providing a second current collector, wherein the second current collector comprises a second body and a tab forming region connected to an edge of the second body, wherein the second body comprises a coating region and a cutting region; Coating a first conductive layer on the surface of the coating area so that the thickness of the electrode piece in the cutting area is smaller than the thickness of the electrode piece in the coating area; Performing cutting in the cutting area to form a target pole piece; The target pole piece forms an edge region in the cutting region, and the thickness of the target pole piece in the edge region is smaller than the thickness of the target pole piece in the coating region.

18. The method according to claim 17, 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.

19. The method according to claim 17 or 18, 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 lug area and a second edge area of ​​the target pole piece, wherein the second edge area is connected between the pole lug area and the coating area.

20. The method according to claim 18, characterized in that A dimension L2 of the first sub-cutting area along a first direction satisfies: 0 mm<L2≤6 mm, and the first direction is perpendicular to a thickness direction of the target pole piece.

21. The method according to claim 19, characterized in that A dimension L3 of the second sub-cutting area along a first direction satisfies: 0 mm<L3≤3 mm, and the first direction is perpendicular to a thickness direction of the target pole piece.

22. The method according to any one of claims 17 to 21, characterized in that Prior to the step of performing cutting in the cutting area, the method further comprises: A second conductive layer is coated on the surface of the cutting area, wherein the solid content of the second conductive layer is less than that of the first conductive layer.

23. The method according to claim 22, characterized in that The solid content A1 of the second conductive layer satisfies: 0%<A1≤1%.

24. The method according to claim 22 or 23, characterized in that The second conductive layer is coated on the surface of the second current collector by a micro-gravure coating process.

25. The method according to any one of claims 17 to 24, characterized in that The solid content A2 of the first conductive layer satisfies: 1.5%≤A2≤10%.

26. The method according to any one of claims 17 to 21, characterized in that Before the step of cutting in the cutting area, the method further comprises: providing an insulating layer on the surface of the cutting area.

27. The method according to any one of claims 17 to 21, characterized in that The cutting area includes a hollow foil area.

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