Pole piece, battery monomer, battery, electric equipment and preparation method of pole piece

Abstract

The embodiment of the invention provides a pole piece, a battery monomer, a battery, electric equipment and a preparation method of the pole piece, the problem of powder falling of the pole piece to be cut in the cutting process can be effectively improved, so that the risk of internal short circuit of the battery monomer caused by lap joint of a positive pole piece and a negative pole piece is reduced, and the yield of the battery monomer is further improved. The pole piece comprises a first current collector, the first current collector comprises a first body and a tab area connected to the edge of the first body, and the first body comprises a coating area and an edge area; the first conductive layer is arranged on the surface of the coating area; wherein the thickness of the pole piece in the edge area is smaller than that of the pole piece in the coating area.

Description

Technical Field

[0001] 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

[0002] As environmental pollution becomes increasingly serious, the new energy industry has attracted more and more attention. In the new energy industry, battery technology is an important factor related to its development.

[0003] The development of battery technology needs to consider many design factors, such as energy density, cycle life, yield rate, etc. The pole piece design in the battery cell is crucial to the yield rate and performance of the battery cell. Therefore, how to provide a pole piece to improve the yield rate of the battery cell has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0004] 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.

[0005] 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.

[0006] In the embodiment of the present application, since the thickness of the electrode sheet in the edge area is less than the thickness of the electrode sheet in the coated area, the edge of the edge area is a cutting edge. When the electrode sheet to be cut is cut and / or die-cut, the problem of powder loss during the cutting process of the electrode sheet 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 sheet and the negative electrode sheet, thereby improving the yield rate of the battery cell.

[0007] 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.

[0008] In the embodiment of the present application, by setting the dimension L1 of the edge area along the first direction to: 0mm<L1≤3mm, the first direction is perpendicular to the thickness direction of the pole piece, which can effectively take into account the yield rate and energy density of the battery cell, thereby improving the performance of the battery.

[0009] In some implementations, the electrode piece further includes a first layer disposed on the surface of the edge region, and the thickness of the first layer is less than the thickness of the first conductive layer. Thus, in the embodiment 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 is the cutting edge, and the thickness of the first layer is less than the thickness of the first conductive layer, which can effectively improve the powder loss problem during the cutting process of the electrode piece to be cut, thereby reducing the risk of internal short circuit of the battery cell caused by the overlap of the positive electrode piece and the negative electrode piece, thereby improving the yield rate of the battery cell.

[0010] In some implementations, the thickness D1 of the first layer satisfies: 0 μm<D1≤1 μm.

[0011] In the embodiment of the present application, by setting the thickness D1 of the first layer to: 0μm<D1≤1μm, and the first layer is arranged on the surface of the edge area of ​​the pole piece, the thickness of the first layer is less than the thickness of the first conductive layer, compared with the prior art, the risk of internal short circuit of the battery cell can be reduced, thereby improving the yield rate of the battery cell.

[0012] In some implementations, the first layer includes a second conductive layer. Thus, in the embodiment 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 pole 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 pole piece to be cut is cut or die-cut, since the edge of the edge region is the cutting edge and the thickness of the second conductive layer is less than the thickness of the first conductive layer, the powdering of the conductive layer during the cutting process or the ablation of the pole piece at the cutting position after laser die-cutting 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.

[0013] 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 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 area is the cutting edge, and the thickness of the second conductive layer is less than the thickness of the first conductive layer, compared with cutting the electrode in the coating area where the first conductive layer is provided, the powdering phenomenon 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.

[0014] In some implementations, the first layer includes an insulating layer. Thus, in the embodiment of the present application, when the electrode to be cut is 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 coating region, the problem of powder falling during the cutting process can be effectively improved, and the risk of internal short circuit of the battery cell can be significantly reduced, thereby improving the yield rate of the battery cell.

[0015] In some implementations, the material of the insulating layer includes at least one of the following materials: boehmite, polyvinylidene fluoride, and ethylene propylene diene monomer rubber. Thus, in the embodiment of the present application, by setting the material of the insulating layer to be at least one of the following materials: boehmite, polyvinylidene fluoride, and ethylene propylene diene monomer rubber, when the electrode to be cut is cut, by setting an insulating layer on the surface of the edge area, 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, significantly reduce the risk of internal short circuit of the battery cell, and thus improve the yield rate of the battery cell.

[0016] In some implementations, the edge region includes a hollow foil region. Thus, in the embodiment of the present application, by providing a hollow foil region on the surface of the edge region, that is, providing a bare surface of the edge region of the pole piece, the problem of powder falling during the cutting process can be effectively improved, and the risk of internal short circuit of the battery cell can be significantly reduced, thereby improving the yield rate of the battery cell.

[0017] In some implementations, the thickness D2 of the first conductive layer satisfies: 2μm≤D2≤20μm. Thus, in the embodiment of the present application, by setting the thickness D2 of the first conductive layer to: 2μm≤D2≤20μm, the uniform distribution of the first conductive layer on the first current collector can be controlled to take into account both the energy density of the battery cell and the yield rate of the battery cell.

[0018] 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.

[0019] In an embodiment of the present application, the edge area includes a first edge area, which is connected to a 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 pole piece to be cut, the edge of the edge area is the cutting edge, and the thickness of the pole piece in the edge area is less than the thickness of the pole piece in the coating area, which can effectively improve the powder falling problem during the cutting process of the pole piece to be cut, thereby reducing the risk of internal short circuit in 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.

[0020] In a second aspect, a battery cell is provided, comprising an electrode assembly, wherein the electrode assembly comprises a pole piece according to any implementation of the first aspect.

[0021] 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 disposed at a position of the positive electrode sheet corresponding to an edge region of the negative electrode sheet.

[0022] 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 caused by overlapping 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.

[0023] In some implementations, the battery cell is an alkali metal battery cell.

[0024] In a third aspect, a battery is provided, comprising the battery cell described in any implementation of the second aspect.

[0025] 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.

[0026] In some implementations, the electrical device may be a vehicle, a ship, or a spacecraft.

[0027] 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.

[0028] 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 coating 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 coating 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.

[0029] 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 pole ear formation area.

[0030] In an embodiment of the present application, by setting at least one first sub-cutting area of ​​the cutting area 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 pole ear 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 then improving the yield rate of the battery cell.

[0031] In some implementations, the second sub-cutting area in the cutting area is disposed between the lug forming area and the coating area, and the method further comprises: cutting in the second sub-cutting area to form the lug area and the second edge area of ​​the target pole piece, the second edge area being connected between the lug area and the coating area. In this way, when the second current collector is die-cut, such as laser die-cutting, the die-cutting position is located in the second sub-cutting area between the lug forming area and the coating area. Since the thickness of the second sub-cutting area is less than the thickness 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 further improving the yield rate of the battery cell.

[0032] In some implementations, the dimension L2 of the first sub-cutting area along the first direction satisfies: 0mm<L2≤6mm, and the first direction is perpendicular to the thickness direction of the target electrode piece. Thus, in the embodiment of the present application, by setting the dimension L2 of the first sub-cutting area along the first direction to: 0mm<L2≤6mm, the yield rate of the battery cell and the energy density of the battery cell can be taken into account at the same time.

[0033] In some implementations, the dimension L3 of the second sub-cutting area along the first direction satisfies: 0mm<L3≤3mm, and the first direction is perpendicular to the thickness direction of the target electrode piece. Thus, in the embodiment of the present application, by setting the dimension L3 of the second sub-cutting area along the first direction to: 0mm<L3≤3mm, the yield rate of the battery cell and the energy density of the battery cell can be taken into account at the same time.

[0034] 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 the solid content of the first conductive layer. Thus, in the embodiment of the present application, the second conductive layer is coated on the surface of the cutting area, wherein the solid content of the second conductive layer is less than the solid content 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 the solid content of the first conductive layer, that is, the thickness of the second conductive layer formed after drying is less than the thickness of the first conductive layer, compared with cutting in the coating area provided with the first conductive layer, when cutting in the cutting area, the powdering phenomenon 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.

[0035] In some implementations, the solid content A1 of the second conductive layer satisfies: 0%<A1≤1%. Thus, in the embodiment of the present application, by setting the solid content A1 of the second conductive layer to: 0%<A1≤1%, the risk of internal short circuit of the battery cell can be reduced, thereby improving the yield rate of the battery cell.

[0036] In some implementations, the second conductive layer is coated on the surface of the second current collector by a micro-gravure coating process. Thus, in the embodiment of the present application, the second conductive layer is coated on the surface of the second current collector by a micro-gravure coating process, so that the second current collector can be evenly coated and the bonding force between the second conductive layer and the surface of the second current collector can be improved, thereby effectively reducing the problem of powder falling during the cutting process, reducing the risk of internal short circuit of the battery cell, and thus improving the yield rate of the battery cell.

[0037] In some implementations, the solid content A2 of the first conductive layer satisfies: 1.5%≤A2≤10%. Thus, in the embodiment of the present application, by setting the solid content A2 of the first conductive layer to: 1.5%≤A2≤10%, the deposition amount of metal ions in the coating area of ​​the pole piece can be improved, thereby increasing the energy density of the battery cell.

[0038] In some implementations, between the steps of cutting in the cutting area, the method further includes: providing an insulating layer on the surface of the cutting area. 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 area, and the thickness of the second current collector in the cutting area is less than the thickness of the second current collector in the coating area, the problem of powder falling during the cutting process can be effectively improved, the risk of internal short circuit of the battery cell can be significantly reduced, and the yield rate of the battery cell can be improved.

[0039] In some implementations, the cutting area includes an empty foil area. Thus, in the embodiment of the present application, by providing an empty foil area on the surface of the cutting area, that is, the surface of the cutting area of ​​the second current collector is exposed, the problem of powder falling during the cutting process can be effectively improved, the risk of internal short circuit of the battery cell can be significantly reduced, and the yield rate of the battery cell can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. 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 paying creative work.

[0041] Figure 1 It is a schematic diagram of the structure of a vehicle provided in one embodiment of the present application.

[0042] Figure 2 It is a schematic diagram of the structure of a battery provided in one embodiment of the present application.

[0043] Figure 3 It is a structural schematic diagram of a battery cell provided in one embodiment of the present application.

[0044] Figure 4 It is a cross-sectional schematic diagram of a pole piece provided in one embodiment of the present application.

[0045] Figure 5 It is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0046] Figure 6 It is a cross-sectional schematic diagram of a pole piece provided in yet another embodiment of the present application.

[0047] Figure 7 It is a cross-sectional schematic diagram of a pole piece provided in yet another embodiment of the present application.

[0048] Figure 8 It is a cross-sectional schematic diagram of a pole piece provided in yet another embodiment of the present application.

[0049] Fig. 9 It is a cross-sectional schematic diagram of a pole piece provided in yet another embodiment of the present application.

[0050] Fig.10 It is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0051] Fig.11 It is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0052] Fig.12 It is a partial cross-sectional schematic diagram of an electrode assembly provided in another embodiment of the present application.

[0053] Fig.13 It is a schematic flowchart of a method for preparing a pole piece provided in one embodiment of the present application.

[0054] Fig.14 It is a cross-sectional schematic diagram of a pole piece to be cut provided in one embodiment of the present application.

[0055] Fig.15 It is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0056] Fig.16 It is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0057] Fig.17It is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0058] Fig.18 It is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0059] Fig.19 It is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0060] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0061] The following detailed description and drawings of the embodiments of the present application are used to illustrate the principles of the embodiments of the present application, but cannot be used 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.

[0062] Unless otherwise defined, all technical and scientific terms used in the embodiments of the present application have the same meanings as those commonly understood by technicians in the technical fields belonging to the embodiments of the present application; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0063] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0064] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0065] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0066] 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).

[0067] In the description of the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings and 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, and therefore should not be understood as a limitation on the embodiments of the present application.

[0068] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0069] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0070] 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 mixed connection through a busbar component.

[0071] 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.

[0072] 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 accommodated in the case.

[0073] In some implementations, the box can be used as part of the chassis structure of the vehicle. For example, part of the box can become at least a part of the floor of the vehicle, or part of the box can become at least a part of the crossbeam and longitudinal beam of the vehicle.

[0074] In some implementations, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0075] 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.

[0076] 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, a magnesium metal battery, or the like.

[0077] 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 embedded and removed back and forth between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, which can prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0078] In some implementations, the positive electrode may be a positive electrode sheet, and the positive electrode sheet 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.

[0079] 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 disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0080] 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, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc., treated with silver surface, may be used. The composite current collector may include a polymer material base 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.).

[0081] 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. Among them, examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO4, which may also be 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 at least one of a composite material of lithium iron manganese phosphate and carbon.

[0082] 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 compound:

[0083] In some implementations, the chemical formula of the sodium transition metal oxide may satisfy Na x MO2, wherein 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, Na x In MO2, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.

[0084] In some implementations, the sodium transition metal oxide may be a doped sodium transition metal oxide, 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.

[0085] In some implementations, the positive electrode may be a foamed metal. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, or a carbon foam. When the foamed metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the foamed metal, but of course, the positive electrode active material may also be provided. As an example, a lithium source material, potassium metal, or sodium metal may also be filled or / and deposited in the foamed metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0086] In some implementations, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0087] As an example, the negative electrode current collector can be a metal foil, a foamed metal or a composite current collector. For example, as a metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. can be used. The composite current collector may include a polymer material base and a metal layer. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an 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.).

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

[0089] In some implementations, the battery cell in the embodiments of the present application may be a negative electrode-free sodium secondary battery.

[0090] 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, a sodium metal or carbonaceous active material layer is not set at the negative electrode through coating or deposition to form a negative electrode active material layer during the manufacturing process of the battery cell. During the first charge, the sodium ions obtain electrons on the anode side to deposit on the surface of the current collector to form a sodium metal phase. During discharge, the metallic sodium can be converted into sodium ions and return to the positive electrode to achieve cyclic charge and discharge. Compared with other sodium secondary batteries, negative electrode-free sodium secondary battery cells can achieve higher energy density because they do not have a negative electrode active material layer.

[0091] 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.

[0092] In some implementations, the CB value of the negative electrode-free sodium secondary battery is less than or equal to 0.1.

[0093] Specifically, the CB value is the unit area capacity of the negative electrode plate in the secondary battery divided by the unit area capacity of the positive electrode plate. Since the negative electrode-free battery does not contain or only contains a small amount of functional coating, the unit area capacity of the negative electrode plate is small, and the CB value of the secondary battery is less than or equal to 0.1.

[0094] 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.

[0095] In some implementations, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0096] In some implementations, the isolation member is an isolation membrane. The embodiment of the present application has no particular limitation on the type of isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.

[0097] 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.

[0098] In some implementations, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0099] In some implementations, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The present application embodiment has no specific restrictions on the type of electrolyte, which can be selected according to needs. The electrolyte can be liquid, gel or solid.

[0100] 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.

[0101] In some implementations, the electrode assembly is a laminate structure. As an example, a plurality of positive plates and a plurality of negative plates may be provided, respectively, and the plurality of positive plates and the plurality of negative plates may be alternately stacked.

[0102] 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.

[0103] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded sections that are stacked.

[0104] As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0105] As an example, the separator may be disposed continuously, and may be disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0106] In some implementations, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0107] In some implementations, the electrode assembly is provided with tabs, which can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0108] In some implementations, the 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 (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0109] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery.

[0110] It should be understood that in the embodiments of the present application, the 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 may be, for example, a battery. A battery may 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 may include, but are not limited to: lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries or magnesium-ion batteries. Battery cells may be cylindrical, flat, rectangular or other shapes.

[0111] In some implementations, functional components may be provided in the energy storage device to manage or assist in the operation of the multiple energy storage elements. For example, a thermal management component may be provided in the energy storage device, and the thermal management component includes but is not limited to an air conditioning component, a fan component, a water cooling pipe, etc., which may be used to perform thermal management on the inside of the energy storage device to adjust the temperature inside the energy storage device. For another example, a control box may be provided in the energy storage device to monitor and control various states of the energy storage device.

[0112] 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 a hybrid connection, where the hybrid connection refers to a mixture of series and parallel connections. Optionally, multiple battery cells can first be connected in series, in parallel, or in a hybrid connection to form a battery module, and multiple battery modules can then be connected in series, in parallel, or in a 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.

[0113] At present, the pole piece design in the battery cell is crucial to the yield rate and performance of the battery cell. For alkali metal batteries in this field, it is usually designed without a negative electrode, that is, only a thin conductive coating is coated on the negative electrode side. Due to the thin thickness of the pole piece, it is difficult for the existing cold pressing equipment to fully press it, resulting in poor adhesion between the conductive coating and the current collector. In the subsequent slitting and die-cutting processes, there may be powder loss or ablation in the cutting area, which is easy to generate dust and burrs, and may cause the positive pole piece and the negative pole piece to overlap and cause the risk of short circuit in the battery cell, affecting the yield rate of the battery cell.

[0114] Specifically, in the battery manufacturing process, slitting refers to cutting the pole piece to be cut into narrower strip-shaped sheets along its length. This is usually achieved through special equipment and tools, such as slitting machines, cutting knives, etc. Slitting can cut the pole piece into strips of different widths as required to meet different application needs. Die cutting refers to cutting the pole piece to be cut through a forming die or laser shearing to form a pole ear of a specific shape and specification on the pole piece to be cut. It should be understood that in the manufacturing process of the pole piece, the slitting process and the die cutting process can be carried out simultaneously or one after another.

[0115] 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 pole ear 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 the overlap of the positive pole piece and the negative pole piece, thereby improving the yield rate of the battery cell.

[0116] The technical solutions described in the embodiments of the present application are applicable to various electrical devices using batteries.

[0117] Electrical equipment can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys and electric tools, etc. Vehicles can be fuel vehicles, gas vehicles or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles and spacecrafts, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc. Electric tools include metal cutting 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.

[0118] 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 equipment using batteries. For the sake of simplicity, the following embodiments are described in detail using the electrical equipment as a vehicle as an example.

[0119] For example, Figure 1As shown, 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 arranged 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 arranged 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 start-up, 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.

[0120] 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 multiple battery cells, wherein the multiple battery cells can be electrically connected in series, parallel or mixed to form the battery 10, wherein mixed refers to a mixture of series and parallel. The battery 10 may also be referred to as a battery pack. For example, multiple battery cells can first be connected in series, parallel or mixed to form a battery module, and multiple battery modules can then be connected in series, parallel or mixed to form a battery 10. In other words, multiple battery cells can directly form a battery 10, or they can be first formed into a battery module, and then the battery modules can be formed into a battery 10.

[0121] In some implementations, the battery 10 may include a plurality of battery cells. Figure 2 , which is a schematic diagram of the structure of a battery 10 according to an embodiment of the present application, wherein the battery 10 may include a plurality of battery cells 20. The battery 10 may also include a housing 11, wherein the interior of the housing 11 is a hollow structure, and the plurality of battery cells 20 are accommodated in the housing 11. For example, the plurality of battery cells 20 are connected in parallel, in series, or in a mixed combination and then placed in the housing 11.

[0122] In some implementations, the battery 10 may also include other structures, which are not described one by one here. For example, the battery 10 may also include a busbar component, which is used to realize electrical connection between multiple battery cells 20, such as parallel connection, series connection, or mixed connection. Specifically, the busbar component can realize 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 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.

[0123] In an 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, in parallel or in a mixed manner to achieve a larger capacity or power. Since the number of battery cells 20 included in each battery 10 may be large, in order to facilitate 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, in parallel or in a mixed manner.

[0124] like Figure 3 As shown, it is a schematic diagram of the structure of a battery cell 20 according to an embodiment of the present application, and 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 a shell or battery box 21. The walls of the shell 211 and the cover plate 212 are both called the walls of the battery cell 20, wherein for a rectangular battery cell 20, the wall of the shell 211 includes a bottom wall and four side walls. The shell 211 is determined according to the shape of one or more electrode assemblies 22 after combination. For example, the shell 211 can be a hollow cuboid or 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 body so that the inside and outside of the shell 211 are connected. When the shell 211 can be a hollow cylinder, the end surface of the shell 211 is an open surface, that is, the end surface has no wall so that the inside and outside of the shell 211 are connected. The cover plate 212 covers the opening and is connected to the shell 211 to form a closed cavity for placing the electrode assembly 22. The shell 211 is filled with an electrolyte, such as an electrolyte.

[0125] 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 generally in the shape of a flat plate, and the two electrode terminals 214 are fixed on the flat surface of the cover plate 212, and 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 connection member, or may also be referred to as a current collecting member, which is located between the cover plate 212 and the electrode assembly 22, and is used to electrically connect the electrode assembly 22 and the electrode terminal 214.

[0126] like Figure 3 As shown, each electrode assembly 22 has a first electrode tab 221a and a second electrode tab 222a. The polarities of the first electrode tab 221a and the second electrode tab 222a are opposite. For example, when the first electrode tab 221a is a positive electrode tab, the second electrode tab 222a is a negative electrode tab.

[0127] In the battery cell 20, the electrode assembly 22 can be provided as a single electrode assembly or multiple electrode assemblies according to actual use requirements. Figure 3 As shown, two independent electrode assemblies 22 are disposed in the battery cell 20 .

[0128] 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.

[0129] The pressure relief mechanism 213 may be a variety of possible pressure relief structures. For example, the pressure relief mechanism 213 may be a temperature-sensitive pressure relief mechanism, which is configured to melt when the internal temperature of the battery cell 20 provided with the pressure relief mechanism 213 reaches a threshold value; and / or, the pressure relief mechanism 213 may be a pressure-sensitive pressure relief mechanism, which is configured to rupture when the internal gas pressure of the battery cell 20 provided with the pressure relief mechanism 213 reaches a threshold value.

[0130] Figure 4 FIG. 1 shows a cross-sectional schematic diagram of a pole piece 50 provided in one embodiment of the present application. Figure 5 A cross-sectional schematic diagram of a pole piece 50 provided in another embodiment of the present application is shown, wherein the Figure 4 and Figure 5 It can be understood as a schematic cross-sectional view of the same pole piece 50 in different directions. For example, Figure 4 It can be a schematic cross-sectional view of the pole piece 50 perpendicular to the thickness direction of the pole piece 50. Figure 5 It may be a schematic cross-sectional view of the pole piece 50 that is perpendicular to the length direction of the pole piece 50 .

[0131] It should be understood that in the embodiments of the present application, for the convenience of description, Figure 4 and Figure 5 As shown, direction X may be the length direction of the pole piece 50, which is perpendicular to direction Y and direction Z; direction Y may be the width direction of the pole piece 50, which is perpendicular to direction X and direction Z; direction Z may be the height direction of the pole piece 50, which is perpendicular to direction X and direction Y, and direction Z may also refer to the thickness direction of the pole piece 50.

[0132] In some implementations, such as Figure 4 and Figure 5As shown, 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.

[0133] It should be understood that in the embodiment of the present application, the first conductive layer 580 is disposed on the surface of the coating area 520, which may mean that the first conductive layer 580 can be disposed on at least one of the two surfaces of the coating area 520 in a direction perpendicular to the thickness of the coating area 520.

[0134] It should also be understood that in the embodiments of the present application, the above Figure 4 and Figure 5 The rectangular pole piece 50 shown in the figure 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.

[0135] 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, a foamed 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.

[0136] It should also be understood that in the embodiment of the present application, the edge region 530 can be understood as a region arranged at the edge of the first body of the first current collector 510. In some implementations, the edge region 530 can be arranged in a region of the first body close to the pole lug region 540. In other implementations, the edge region 530 can also be arranged in a region of the first body away from the pole lug region 540.

[0137] 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 also 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.

[0138] In the embodiment of the present application, since 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, the edge of the edge area 530 is a cutting edge. When the pole piece to be cut is cut and / or die-cut, the problem of powder loss of the pole piece to be cut during the cutting process can be effectively improved, thereby reducing the risk of internal short circuit in the battery cell 20 caused by overlapping of the positive pole piece 502 and the negative pole piece 501, thereby improving the yield rate of the battery cell 20.

[0139] In some implementations, such as Figure 4 and Figure 5 As shown, the dimension L1 of the edge region 530 along the first direction satisfies: 0mm<L1≤3mm, and the first direction is perpendicular to the thickness direction of the pole piece 50. Exemplarily, in the embodiment of the present application, the first direction may be direction Y or direction X.

[0140] It should be understood that in the embodiments of the present application, Figure 4 and Figure 5 As shown, along the direction Y, the pole piece 50 may be provided with two edge regions 530. For example, the edge region 530 of the first body of the first current collector 510 away from the pole lug 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 pole lug 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.

[0141] 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 its value is 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.

[0142] 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, the first direction is perpendicular to the thickness direction of the pole piece 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.

[0143] In some implementations, such as Figure 4 and Figure 5As shown, 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 may be disposed on at least one of the two surfaces of the edge region 530 in a direction perpendicular to the thickness of the edge region 530.

[0144] 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 .

[0145] Thus, in the embodiment of the present application, when the electrode piece 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 piece to be cut can be effectively improved, thereby reducing the risk of internal short circuit of the battery cell 20 caused by overlapping of the positive electrode piece 502 and the negative electrode piece 501, thereby improving the yield rate of the battery cell 20.

[0146] In some implementations, such as Figure 5 As shown, the thickness D1 of the first layer 550 satisfies: 0 μm<D1≤1 μm.

[0147] Exemplarily, the thickness D1 of the first layer 550 in the embodiment of the present application may be: 0.05μm, 0.1μm, 0.15μm, 0.20μm, 0.25μm, 0.30μm, 0.35μm, 0.40μm, 0.45μm, 0.50μm, 0.55μm, 0.60μm, 0.65μm, 0.70μm, 0.75μm, 0.80μm, 0.85μm, 0.90μm, 0.95μm, 1μm, or its value is 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.

[0148] In the embodiment of the present application, by setting the thickness D1 of the first layer 550 to: 0μm<D1≤1μm, 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.

[0149] In some implementations, such as Figure 4 and Figure 5 As shown, the first layer 550 includes a second conductive layer 560 .

[0150] 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 in a thickness direction perpendicular to the edge area 530.

[0151] 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 pole piece 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 pole piece 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 pole piece 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 further improving the yield rate of the battery cell 20.

[0152] 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 at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon, when the electrode piece 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, compared with cutting the electrode piece in the coating region 520 where the first conductive layer 580 is provided, 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 further improving the yield rate of the battery cell 20.

[0153] In some implementations, such as Figure 4 and Figure 5 As shown, the first layer 550 includes an insulating layer 570 .

[0154] 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 region 530 in a thickness direction perpendicular to the edge region 530.

[0155] 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 problem of powder falling 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 rate of the battery cell 20.

[0156] In some implementations, the material of the insulating layer 570 includes at least one of the following materials: boehmite, polyvinylidene fluoride, and ethylene propylene diene rubber. Thus, in the embodiment of the present application, by setting the material of the insulating layer 570 to at least one of the following materials: boehmite, polyvinylidene fluoride, and ethylene propylene diene rubber, when the electrode to be cut is cut, by setting the insulating layer 570 on the surface of the edge area 530, 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, which can effectively improve the powder falling problem during the cutting process, significantly reduce the risk of internal short circuit of the battery cell 20, and thus improve the yield rate of the battery cell 20.

[0157] Figure 6 FIG. 2 shows a cross-sectional schematic diagram of a pole piece 50 provided in another embodiment of the present application. Figure 7 FIG. 5 shows a cross-sectional schematic diagram of a pole piece 50 provided in another embodiment of the present application. Figure 6 and Figure 7 It can be understood as a schematic cross-sectional view of the same pole piece 50 in different directions. Figure 6 It can be a schematic cross-sectional view of the pole piece 50 perpendicular to the thickness direction of the pole piece 50, Figure 7 It may be a schematic cross-sectional view of the pole piece 50 that is perpendicular to the length direction of the pole piece 50 .

[0158] In some implementations, such as Figure 6 and Figure 7 As shown, the edge region 530 includes a hollow foil region. Thus, in the embodiment of the present application, by providing a hollow foil region on the surface of the edge region 530, that is, the surface of the edge region 530 of the pole piece 50 is exposed, 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 rate of the battery cell 20.

[0159] In some implementations, such as Figures 4 to 7 As shown, the thickness D2 of the first conductive layer 580 satisfies: 2 μm≤D2≤20 μm.

[0160] Exemplarily, the thickness D2 of the first conductive layer 580 may be: 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, or its value is 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: 4μm≤D2≤10μm.

[0161] Thus, in the embodiment of the present application, by setting the thickness D2 of the first conductive layer 580 to: 2μm≤D2≤20μm, 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.

[0162] Figure 8 FIG. 2 shows a cross-sectional schematic diagram of a pole piece 50 provided in another embodiment of the present application. Fig. 9 FIG. 5 shows a cross-sectional schematic diagram of a pole piece 50 provided in another embodiment of the present application. Figure 8 and Fig. 9 It can be understood as a schematic cross-sectional view of the same pole piece 50 in different directions. Figure 8 It can be a schematic cross-sectional view of the pole piece 50 perpendicular to the thickness direction of the pole piece 50, Fig. 9 It may be a schematic cross-sectional view of the pole piece 50 that is perpendicular to the length direction of the pole piece 50 . Fig.10 FIG. 2 shows a cross-sectional schematic diagram of a pole piece 50 provided in another embodiment of the present application. Fig.11 FIG. 5 shows a cross-sectional schematic diagram of a pole piece 50 provided in another embodiment of the present application. Fig.10 and Fig.11 It can be understood as a schematic cross-sectional view of the same pole piece 50 in different directions. Fig.10 It can be a schematic cross-sectional view of the pole piece 50 perpendicular to the thickness direction of the pole piece 50, Fig.11 It may be a schematic cross-sectional view of the pole piece 50 that is perpendicular to the length direction of the pole piece 50 .

[0163] In some implementations, such as Figures 4 to 11 As shown, the edge region 530 includes a first edge region 531, which is connected to a side of the coating region 520 away from the lug region 540, and / or the edge region 530 includes a second edge region 532, which is connected between the lug region 540 and the coating region 520.

[0164] For example, Figure 8 and Fig. 9As shown, the first body of the first current collector 510 of the pole piece 50 includes an edge region 530, and the edge region 530 may be a first edge region 531, and the first edge region 531 is connected to a side of the coating region 520 away from the pole ear region 540. For another example, Fig.10 and Fig.11 As shown, the first body of the first current collector 510 of the pole piece 50 includes an edge region 530 , and the edge region 530 may be a second edge region 532 . The second edge region 532 is connected between the tab region 540 and the coating region 520 .

[0165] 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 is connected to a side of the coating region 520 away from the pole ear region 540, and the second edge region 532 is connected between the pole ear region 540 and the coating region 520. In this way, when cutting the pole piece to be cut, the edge of the edge region 530 is the cutting edge, and the thickness H1 of the pole piece 50 in the edge region 530 is less than the thickness H2 of the pole piece 50 in the coating region 520, which can effectively improve the powder falling problem of the pole piece to be cut during the cutting process, thereby reducing the risk of internal short circuit of the battery cell 20 caused by overlapping of the positive pole piece 502 and the negative pole piece 501, thereby improving the yield rate of the battery cell 20.

[0166] The present application also provides a battery cell, including an electrode assembly 22, wherein the electrode assembly includes the electrode sheet 50 in the above embodiment. Figure 3 The battery cell 20 is shown in FIG.

[0167] Fig.12 FIG. 2 shows a partial cross-sectional schematic diagram of an electrode assembly 22 provided in an embodiment of the present application. Fig.12 As shown, the electrode assembly 22 includes a negative electrode sheet 501 , a positive electrode sheet 502 and an isolating member 503 , and the isolating member 503 is disposed between the negative electrode sheet 501 and the positive electrode sheet 502 .

[0168] In some implementations, such as Fig.12 As shown, 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 a position of the positive electrode sheet 502 corresponding to the edge area of ​​the negative electrode sheet 501 .

[0169] 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.

[0170] 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 at the position 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, due to the provision of the insulating layer 570, the risk of internal short circuit in the battery cell 20 caused by overlapping of the positive electrode sheet 502 and the negative electrode sheet 501 can be effectively reduced, thereby improving the yield rate of the battery cell 20.

[0171] In some implementations, the battery cell 20 is an alkali metal battery cell.

[0172] The present application also provides a battery, including the battery cell 20 in the above embodiment. Figure 2 The battery 10 is shown in FIG.

[0173] The present application also provides an electric device, including the battery 10 in the above embodiment, and the battery 10 is used to provide electric energy for the electric device. Specifically, the electric device can be Figure 1 The vehicle 1 shown may also be any device using the battery 10 .

[0174] Fig.13 A flowchart of a method for preparing a pole piece 60 to be cut provided in an embodiment of the present application is shown. Fig.14 FIG. 1 shows a cross-sectional schematic diagram of a pole piece 60 to be cut provided in an embodiment of the present application. Fig.15 FIG. 2 shows a cross-sectional schematic diagram of another pole piece 60 to be cut provided by another embodiment of the present application. Fig.16 FIG. 2 shows a cross-sectional schematic diagram of another pole piece 60 to be cut provided by another embodiment of the present application. Fig.17 FIG. 2 shows a cross-sectional schematic diagram of another electrode piece 60 to be cut provided by another embodiment of the present application. Fig.14 and Fig.15 It can be understood as a schematic cross-sectional view of the same pole piece 60 to be cut in different directions. Fig.14 It can be a schematic cross-sectional view of the electrode piece 60 to be cut perpendicular to the thickness direction of the electrode piece 60 to be cut. Fig.15 It can be a schematic cross-sectional view of the electrode piece 60 to be cut perpendicular to the length direction of the electrode piece 60 to be cut. Fig.16 and Fig.17 It can be understood as a schematic cross-sectional view of the same electrode piece 60 to be cut in different directions. Fig.16 It can be a schematic cross-sectional view of the electrode piece 60 to be cut that is perpendicular to the thickness direction of the electrode piece 60 to be cut. Fig.17 It may be a schematic cross-sectional view of the pole piece 60 to be cut that is perpendicular to the length direction of the pole piece 60 to be cut.

[0175] In some implementations, such as Figures 13 to 17 As shown, the preparation method of 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 includes a second body and a pole ear forming area 630 connected to the edge of the second body, and the second body includes 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.

[0176] It should be understood that in the embodiment of the present application, the target pole piece includes but is not limited to the above Figures 4 to 12 The pole piece 50 is shown in FIG.

[0177] It should also be understood that in the embodiment of the present application, the thickness of the target pole piece in the edge region 530 may be as described above. Figures 4 to 12 The thickness H1 of the electrode piece 50 in the edge region 530 is shown in FIG. The thickness of the target electrode piece in the coating region 520 may be as described above. Figures 4 to 12 The thickness H2 of the pole piece 50 in the coating area 520 is shown.

[0178] 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.

[0179] It should also be understood that in some implementations, such as Fig.14 and Fig.16As shown, cutting in the cutting area 620 may mean that in the slitting process of the electrode piece 60 to be cut, the cutting area 620 includes a first sub-cutting area 621, the electrode piece 60 to be cut may be cut along a first cutting line 641, and the cutting area 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 in the cutting area 620 may also mean that in the die-cutting process of the electrode piece 60 to be cut, the cutting area 620 includes a second sub-cutting area 622, the electrode piece 60 to be cut may be cut along a second cutting line 642, so as to form a pole ear portion at the edge of the second current collector 510.

[0180] It should also be understood that in the embodiments of the present application, the above Figures 14 to 17 The rectangular pole piece 60 to be cut shown in the figure 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.

[0181] In an embodiment of the present application, by setting the thickness H3 of the pole piece 60 to be cut in the cutting area 620 to be smaller than the thickness H4 of the pole 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 pole piece 60 to be cut in the cutting area 620 is smaller than the thickness H4 of the pole 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 caused by overlapping of the positive pole piece 502 and the negative pole piece 501, thereby improving the yield rate of the battery cell 20.

[0182] In some implementations, such as Figures 14 to 17 As shown, the coating area 520 includes at least two sub-coating areas, at least one first sub-cutting area 621 of the cutting area 620 is arranged between the two sub-coating areas, and 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 forming area 630.

[0183] For example, Fig.14 and Fig.16 As shown, 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.

[0184] It should be understood that in the embodiment of the present application, cutting can be performed in the first sub-cutting area 621 to form a first edge area 531 on the side of the coating area 520 away from the tab forming area 630. The first edge area 531 can be the above-mentioned Figures 4 to 12 The first edge region 531 of the pole piece 50 is shown in FIG.

[0185] In an embodiment of the present application, by setting at least one first sub-cutting area 621 of the cutting area 620 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 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 forming 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 then improving the yield rate of the battery cell 20.

[0186] In some implementations, such as Figures 14 to 17 As shown, the second sub-cutting area 622 in the cutting area 620 is arranged between the pole ear forming 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 ear area 540 and the second edge area 532 of the target pole piece, and the second edge area 532 is connected between the pole ear area 540 and the coating area 520.

[0187] 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 pole piece 60. Exemplarily, in the process of die-cutting the to-be-cut pole 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.

[0188] 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 pole ear forming 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 further improving the yield rate of the battery cell 20.

[0189] In some implementations, such as Figures 14 to 17 As shown, the dimension L2 of the first sub-cutting area 621 along the first direction satisfies: 0mm<L2≤6mm, and the first direction is perpendicular to the thickness direction of the target pole piece.

[0190] Exemplarily, 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 its value is 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.

[0191] 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.

[0192] In some implementations, such as Figures 13 to 17 As shown, the dimension L3 of the second sub-cutting area 622 along the first direction satisfies: 0mm<L3≤3mm, and the first direction is perpendicular to the thickness direction of the target pole piece.

[0193] Exemplarily, 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.

[0194] 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.

[0195] In some implementations, such as Fig.14 and Fig.15 As shown, between the steps of cutting in the cutting area 620 , the method further includes: coating a second conductive layer 560 on the surface of the cutting area 620 , wherein the solid content A1 of the second conductive layer 560 is less than the solid content A2 of the first conductive layer 580 .

[0196] 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 in a thickness direction perpendicular to the cutting area 620.

[0197] 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 further improving the yield rate of the battery cell 20.

[0198] In some implementations, the solid content A1 of the second conductive layer 560 satisfies: 0%<A1≤1%.

[0199] It should be understood that the solid content in the embodiment of the present application refers to the percentage of the mass of the remaining part of the slurry used to coat the surface of the second current collector 610 after drying under specified conditions to the mass of the original slurry. For example, in the embodiment of the present application, the conductive carbon material and carboxymethyl cellulose are mixed in a certain ratio to form a coating slurry with a solid content of 0.5%, and the coating slurry is evenly coated on the surface of the edge area 530 of the pole piece 50, and then dried, compacted, and other processes are performed to form the second conductive layer 560.

[0200] 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 its value is 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%.

[0201] 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 rate of the battery cell 20.

[0202] 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.

[0203] It should be understood that when the second current collector 610 in the embodiment of the present application is coated, a gravure coating process is usually used. A back roller is provided in the gravure coating process. The function of the back roller is to make the second current collector 610 better contact 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 on the coating on the surface of the second current collector 610, resulting in uneven coating, which affects 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 which is mounted on a bearing and partially immersed in the feed tray. The coating is brought 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 uniform thin layer coating can be achieved.

[0204] In an embodiment of the present application, the second conductive layer 560 is coated on the surface of the second current collector 610 by 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 problem of powder loss 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.

[0205] In some implementations, such as Figures 14 to 17 As shown, the solid content A2 of the first conductive layer 580 satisfies: 1.5%≤A2≤10%.

[0206] 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 a 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%.

[0207] 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.

[0208] In some implementations, such as Fig.14 and Fig.15 As shown, 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 .

[0209] 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.

[0210] 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 problem of powder falling 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 rate of the battery cell 20.

[0211] In some implementations, such as Fig.16 and Fig.17 As shown, the cutting area 620 includes an empty foil area. Thus, in the embodiment of the present application, by setting an empty foil area on the surface of the cutting area 620, that is, the surface of the cutting area 620 of the second current collector 610 is exposed, 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 rate of the battery cell 20.

[0212] Fig.18 FIG. 2 shows a cross-sectional schematic diagram of a pole piece 60 to be cut provided in another embodiment of the present application. Fig.19 FIG. 1 shows a cross-sectional schematic diagram of a pole piece 60 to be cut provided in another embodiment of the present application. Fig.18 and Fig.19 It can be understood as a schematic cross-sectional view of the same pole piece 60 to be cut in different directions. Fig.18 It can be a schematic cross-sectional view of the electrode piece 60 to be cut perpendicular to the thickness direction of the electrode piece 60 to be cut. Fig.19 It may be a schematic cross-sectional view of the pole piece 60 to be cut that is perpendicular to the length direction of the pole piece 60 to be cut.

[0213] In some implementations, such as Fig.18 and Fig.19 As shown, 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 pole ear forming region 630, a coating region 520 and a second sub-cutting region 622, the second sub-cutting region 622 is arranged between the pole ear forming 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 μm, a second conductive layer 560 is coated on the surface of the second sub-cutting region 622 by a micro-gravure coating process, the thickness D1 of the second conductive layer 560 is 0.5 μm, and the dimension L3 of the second sub-cutting 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 the second cutting line 642 in the second sub-cutting region 622 to form a target pole piece.

[0214] In some implementations, see again above Figure 4 and Figure 5, a pole piece 50 is provided, the pole piece 50 comprises: 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 the edge of the first body, the first body comprises a coating region 520 and an edge region 530, the first conductive layer 580 is arranged on the surface of the coating region 520, wherein 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, wherein 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, that is, 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.

[0215] Although the present application has been described with reference to the above embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling 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 μm<D1≤1 μm.

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 μm≤D2≤20 μm.

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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