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 yield of the battery monomer can be improved. The pole piece comprises a first current collector, a first conductive layer and a first layer, the first current collector comprises a first body and a tab area connected to the edge of the first body, the first body comprises a coating area and an edge area, the first conductive layer is arranged on the surface of the coating area, the first layer is arranged on the surface of the edge area, and the first layer is arranged on the surface of the first conductive layer. A porosity of the first layer is less than a porosity of the first conductive layer.

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 ear region connected to the edge of the first body, the first body comprising a coating region and an edge region; a first conductive layer, the first conductive layer being arranged on the surface of the coating region; a first layer, the first layer being arranged on the surface of the edge region; wherein the porosity of the first layer is less than the porosity of the first conductive layer.

[0006] In an embodiment of the present application, the first current collector includes a first body, a first conductive layer is provided on the surface of the coated area of ​​the first body, a first layer is provided in the edge area of ​​the first body, and the porosity of the first layer is less than the porosity of the first conductive layer, that is, the density of the first layer is higher than the density of the first conductive layer, and the problem of powder falling of the electrode to be cut during the cutting of the edge area can be improved by improving the density of the first layer, thereby reducing the risk of internal short circuit of the battery cell due to overlap of the positive electrode plate and the negative electrode plate, thereby improving the yield rate of the battery cell.

[0007] In some implementations, the porosity A1 of the first layer satisfies: 0%<A1≤50%. Thus, in the embodiment of the present application, the porosity of the first layer is less than the porosity of the first conductive layer, and the porosity A1 of the first layer is set to 0%<A1≤50%, which can effectively improve the powder loss problem of the electrode to be cut during the cutting of the edge area by increasing the density of the first layer, thereby reducing the risk of internal short circuit of the battery cell caused by the overlap of the positive electrode and the negative electrode, thereby improving the yield rate of the battery cell.

[0008] In some implementations, the porosity A1 of the first layer satisfies: 20%≤A1≤30%. Thus, in the embodiment of the present application, the porosity of the first layer is less than the porosity of the first conductive layer, and the porosity A1 of the first layer is set to 20%≤A1≤30%, which can further improve the powder loss problem of the electrode to be cut during the cutting of the edge area by increasing the density of the first layer, thereby reducing the risk of internal short circuit of the battery cell caused by the overlap of the positive electrode and the negative electrode, thereby improving the yield rate of the battery cell.

[0009] In some implementations, the ratio L1 / D1 between the dimension L1 of the edge region along the first direction and the thickness D1 of the first conductive layer satisfies: 10≤L1 / D1≤1000, preferably, 20≤L1 / D1≤100, wherein the first direction is perpendicular to the thickness direction of the pole piece. Thus, in the embodiment of the present application, by setting the ratio L1 / D1 between the dimension L1 of the edge region along the first direction and the thickness D1 of the first conductive layer to 10≤L1 / D1≤1000, and preferably, the value of L1 / D1 can also be set to 20≤L1 / D1≤100, it is possible to reduce the thermal impact on the first conductive layer during the laser die-cutting process, reduce the powder loss problem caused by the thermal expansion of the first conductive layer during the cutting process of the pole piece, and thus improve the manufacturing performance of the battery.

[0010] In some implementations, the dimension L1 of the edge region along the first direction satisfies: 2mm≤L1≤20mm. Thus, in the embodiment of the present application, the dimension L1 of the edge region along the first direction is set to 2mm≤L1≤20mm, so as to adjust the dimension L1 of the edge region along the first direction to adjust the dimension of the coating region along the first direction, so as to improve the conductivity of the first conductive layer, thereby improving the energy density of the battery.

[0011] In some implementations, the dimension L1 of the edge region along the first direction satisfies: 3mm≤L1≤6mm. Thus, in the embodiment of the present application, by setting the dimension L1 of the edge region along the first direction to 3mm≤L1≤6mm, the dimension L1 of the edge region along the first direction is adjusted to adjust the dimension of the coating region along the first direction, so as to further improve the conductivity of the first conductive layer, thereby improving the energy density of the battery.

[0012] In some implementations, the thickness D1 of the first conductive layer satisfies: 1 μm ≤ D1 ≤ 50 μm. Thus, in the embodiment of the present application, by setting the thickness D1 of the first conductive layer to 1 μm ≤ D1 ≤ 50 μm, the conductivity of the first conductive layer can be improved by controlling the thickness D1 of the first conductive layer, thereby improving the energy density of the battery.

[0013] In some implementations, the material of the first conductive layer includes at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon. Thus, in the embodiment of the present application, by setting the material of the first conductive layer to at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon, the conductive performance of the pole piece can be improved, thereby improving the energy density of the battery.

[0014] In some implementations, the first layer extends to the tab region. Thus, in the embodiment of the present application, by extending the first layer to the tab region, that is, the first layer can be disposed on at least a portion of the surface of the tab region, the tab region can be strengthened to reduce deformation and cracking of the pole piece during the cutting process and the subsequent winding process, thereby improving the performance of the battery, facilitating the processing and manufacturing of the pole piece, and improving the manufacturing performance of the battery.

[0015] In some implementations, the first layer also extends to the surface of the first conductive layer away from the first current collector. Thus, in the embodiment of the present application, by extending the first layer to the coating area, the processing and manufacturing of the pole piece is facilitated, thereby improving the manufacturing performance of the battery.

[0016] 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 ​​the metal ions on the electrode sheet can be increased, the conductivity of the electrode sheet can be improved, and thus the energy density of the battery can be improved.

[0017] In some implementations, the material of the second conductive layer includes at least one of the following materials: carbon nanotubes, graphene, and conductive graphite.

[0018] In the embodiment of the present application, by setting the material of the second conductive layer to at least one of the following materials: carbon nanotubes, graphene, and conductive graphite, the conductive performance of the pole piece can be significantly improved, thereby improving the energy density of the battery.

[0019] In some implementations, the thickness D2 of the second conductive layer satisfies: 2μm≤D2≤150μm, preferably, 70μm≤D2≤120μm. In the embodiment of the present application, by setting the thickness D2 of the second conductive layer to 2μm≤D2≤150μm, preferably, the thickness D2 of the second conductive layer can also be set to: 70μm≤D2≤120μm, the conductivity of the second conductive layer can be improved by controlling the thickness D2 of the second conductive layer, thereby improving the energy density of the battery.

[0020] In some implementations, the material of the second conductive layer includes conductive carbon, and the thickness D2 of the second conductive layer satisfies: 10μm≤D2≤70μm. In the embodiment of the present application, when the material of the second conductive layer is set to conductive carbon, since the conductive carbon is a fluffy structure with a large porosity, compaction treatment is required after the second conductive layer is coated on the edge area to reduce the porosity of the second conductive layer. Secondly, by setting the thickness D2 of the second conductive layer on the surface of the edge area to 10μm≤D2≤70μm, the conductivity of the second conductive layer can be improved by controlling the thickness D2 of the second conductive layer, thereby improving the energy density of the battery.

[0021] In some implementations, the first layer includes an insulating layer. Thus, in the embodiment of the present application, by providing an insulating layer on the surface of the edge region, the insulation performance of the electrode in the edge region can be improved, and the deposition of metal at the edge of the electrode can be effectively reduced, thereby improving the yield rate of the battery cell.

[0022] In some implementations, the thickness D3 of the insulating layer satisfies: 5μm≤D3≤100μm, preferably, 5μm≤D3≤20μm. Thus, in the embodiment of the present application, by setting the material of the second conductive layer as the insulating layer, and setting the thickness D3 of the insulating layer to 5μm≤D3≤100μm, preferably, 5μm≤D3≤20μm, the deposition of metal ions at the edge of the pole piece can be reduced by adjusting the thickness D3 of the insulating layer, while facilitating the processing and manufacturing of the pole piece, and improving the manufacturing performance of the battery.

[0023] In some implementations, the material of the insulating layer includes at least one of the following materials: boehmite, polyvinylidene fluoride, ethylene propylene diene rubber, and polyimide. Thus, in the embodiment of the present application, by setting the material of the insulating layer to at least one of the following materials: boehmite, polyvinylidene fluoride, ethylene propylene diene rubber, and polyimide, the insulation performance of the electrode in the edge area can be significantly improved, while reducing the deposition of metal ions at the edge of the electrode, while facilitating the processing and manufacturing of the electrode, and improving the manufacturing performance of the battery.

[0024] 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.

[0025] 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 porosity of the second conductive layer is smaller than the porosity of the first conductive layer, that is, the density of the second conductive layer is higher than the density of the first conductive layer, which can effectively improve the powder falling problem at the edge area 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] In some implementations, the battery cell is an alkali metal battery cell. Thus, in the embodiment of the present application, by setting the battery cell as an alkali metal battery cell, the energy density of the battery and the reliability of its performance can be improved.

[0030] In a third aspect, a battery is provided, comprising the battery cell described in any implementation of the second aspect.

[0031] In a fourth aspect, an electrical device is provided, comprising: the battery described in the third aspect above, wherein the battery is used to provide electrical energy to the electrical device.

[0032] In some implementations, the electrical device may be a vehicle, a ship, or a spacecraft.

[0033] In a fifth aspect, a method for preparing a pole piece is provided, comprising: providing a second current collector, the second current collector comprising a second body and a pole ear forming area connected to the edge of the second body, the second body comprising a coating area and a cutting area; coating a first conductive layer on the surface of the coating area; coating a first layer on the surface of the cutting area; cutting in the cutting area to form a pole piece in any possible implementation of the first aspect; wherein the porosity of the first layer is less than the porosity of the first conductive layer.

[0034] In an embodiment of the present application, the second current collector includes a second body, a first conductive layer is coated on the surface of the coating area, and a first layer is coated on the surface of the cutting area. When cutting is performed in the cutting area, since the porosity of the first layer is smaller than the porosity of the first conductive layer, that is, the density of the first layer is higher than the density of the first conductive layer, the problem of powder falling generated by the electrode to be cut during the cutting process in the cutting area can be improved by increasing the density of the first layer, 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.

[0035] In some implementations, before cutting in the cutting area, the method further includes: coating the first layer on the surface of the area of ​​the tab formation area close to the second body. Thus, in the embodiment of the present application, by coating the first layer on the surface of the area of ​​the tab formation area close to the second body, the tab formation area can be strengthened to reduce deformation and cracking of the pole piece to be cut during the cutting process and the subsequent winding process, thereby improving the performance of the battery.

[0036] In some implementations, before cutting in the cutting area, the method further includes: coating the first layer on the surface of the first conductive layer away from the second current collector. Thus, in the embodiment of the present application, by coating the first layer on the surface of the first conductive layer away from the second current collector, during the cutting process of the electrode piece to be cut, for example, during laser die cutting, the heat effect on the first conductive layer near the cutting area during the laser die cutting process can be reduced, and the ablation phenomenon at the edge of the cutting position can be reduced, thereby improving the performance of the battery.

[0037] 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 cutting area, the deposition area of ​​the metal ions on the target electrode piece can be increased, the conductivity of the electrode piece can be improved, and thus the energy density of the battery can be improved.

[0038] In some implementations, the first layer includes an insulating layer. Thus, in the embodiment of the present application, by providing an insulating layer on the surface of the cutting area, the insulation performance of the electrode in the edge area can be improved, and the deposition of metal at the edge of the electrode can be effectively reduced, thereby improving the yield rate of the battery cell.

[0039] In some embodiments, the coating area includes at least two sub-coating areas, and a 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 a side of the coating area away from the pole ear formation area.

[0040] In an embodiment of the present application, a first sub-cutting area in the cutting area is set between two sub-coating areas, and cutting is performed in the first sub-cutting area to form a first edge area on the side of the coating area away from the pole ear formation area. Since the porosity of the first layer coated in the first sub-cutting area is smaller than the porosity of the first conductive layer, that is, the density of the first layer is higher than the density of the first conductive layer, the problem of powder falling 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.

[0041] 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 includes: 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. Thus, in an embodiment of the present application, when the pole piece to be cut is subjected to a cutting process, such as a laser die-cutting process, the die-cutting position is located in the second sub-cutting area between the lug forming area and the coating area. Since the porosity of the first layer coated in the second sub-cutting area is less than the porosity of the first conductive layer, that is, the density of the first layer is higher than the density of the first conductive layer, the ablation phenomenon occurring at the die-cutting position of the cutting area during the laser die-cutting process can be reduced, and the powder loss phenomenon during the cutting process can be reduced, thereby reducing the risk of internal short circuit of the battery cell, and thus improving the yield rate of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] 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.

[0043] Figure 1 It is a schematic diagram of the structure of a vehicle provided in one embodiment of the present application.

[0044] Figure 2 It is a schematic diagram of the structure of a battery provided in one embodiment of the present application.

[0045] Figure 3 It is a structural schematic diagram of a battery cell provided in one embodiment of the present application.

[0046] Figure 4 It is a cross-sectional schematic diagram of a pole piece provided in one embodiment of the present application.

[0047] Figure 5 It is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0048] Figure 6 It is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0049] Figure 7 It is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0050] Figure 8 It is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0051] Fig. 9 It is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0052] Fig.10 It is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0053] Fig.11 It is a cross-sectional schematic diagram of a pole piece provided in another embodiment of the present application.

[0054] Fig.12 It is a partial cross-sectional schematic diagram of an electrode assembly provided in one embodiment of the present application.

[0055] Fig.13 It is a schematic flowchart of a method for preparing a pole piece provided in one embodiment of the present application.

[0056] Fig.14 It is a cross-sectional schematic diagram of a pole piece to be cut provided in one embodiment of the present application.

[0057] Fig.15 It is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0058] Fig.16 It is a cross-sectional schematic diagram of a pole piece to be cut provided in another embodiment of the present application.

[0059] Fig.17 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] 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.

[0082] In some implementations, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0083] 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.).

[0084] In some implementations, the battery cell in the embodiments of the present application may be a negative electrode metal-free battery.

[0085] In some implementations, the battery cell in the embodiments of the present application may be a negative electrode-free sodium secondary battery.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] In some implementations, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] In some implementations, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] At present, the pole piece design in the battery cell is crucial to the yield rate and performance of the battery cell. Usually, a layer of low-density conductive coating is coated on the surface of the pole piece. In the subsequent die-cutting process, if the power of the laser die-cutting is low, there may be a risk that it cannot be cut off, and the remaining part is prone to form burrs; and when the power of the laser die-cutting is high, the edge of the cutting area is ablated, making the conductive coating brittle and easy to fall off, generating dust and burrs, which 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. 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.

[0106] In view of this, an embodiment of the present application provides a pole piece, comprising: a first current collector, the first current collector comprising a first body and a pole ear region connected to the edge of the first body, the first body comprising a coating region and an edge region; a first conductive layer, the first conductive layer being arranged on the surface of the coating region; a first layer, the first layer being arranged on the surface of the edge region; wherein the porosity of the first layer is less than the porosity of the first conductive layer. Thus, in an embodiment of the present application, the first current collector comprises a first body, the surface of the coating region of the first body is provided with a first conductive layer, the edge region of the first body is provided with a first layer, and the porosity of the first layer is less than the porosity of the first conductive layer, that is, the density of the first layer is higher than the density of the first conductive layer, and the powder falling problem of the pole piece to be cut during the cutting of the edge region can be improved by improving the density of the first layer, thereby reducing the risk of internal short circuit of the battery cell caused by the overlap of the positive pole piece and the negative pole piece, thereby improving the yield rate of the battery cell.

[0107] 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.

[0108] 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.

[0109] For example, Figure 1 As 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] like Figure 3As 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.

[0115] 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.

[0116] 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.

[0117] 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 .

[0118] 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.

[0119] 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.

[0120] 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 FIG. 5 shows a cross-sectional schematic diagram of a pole piece 50 provided in another embodiment of the present application. 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 .

[0121] It should be understood that in the embodiments of the present application, for the convenience of description, three directions are defined here, such as Figure 4 and Figure 5 As shown, the first direction X may be the length direction of the pole piece 50, and the first direction X is perpendicular to the second direction Y and the third direction Z; the second direction Y may be the width direction of the pole piece 50, and the second direction Y is perpendicular to the first direction X and the third direction Z; the third direction Z may be the height direction of the pole piece 50, and the third direction Z is perpendicular to the first direction X and the second direction Y, and the third direction Z may also refer to the thickness direction of the pole piece 50.

[0122] In some implementations, such as Figures 4 to 5 As shown, the pole piece 50 includes: a first current collector 510, a first conductive layer 560 and a first layer 550, the first current collector 510 includes a first body and a pole ear area 540 connected to the edge of the first body, the first body includes a coating area 520 and an edge area 530, the first conductive layer 560 is arranged on the surface of the coating area 520, and the first layer 550 is arranged on the surface of the edge area 530, wherein the porosity of the first layer 550 is less than the porosity of the first conductive layer 560.

[0123] It should be understood that, in the embodiment of the present application, the first conductive layer 560 is disposed on the surface of the coating region 520, which may mean that the first conductive layer 560 may be disposed on at least one of the two surfaces of the coating region 520 in a direction perpendicular to the thickness of the coating region 520. In the embodiment of the present application, the first layer 550 is 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.

[0124] 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 square, a parallelogram and a polygon.

[0125] 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.

[0126] 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.

[0127] It should also be understood that in the embodiment of the present application, the porosity of the first layer 550 and the first conductive layer 560 in the embodiment of the present application can be measured by the true density method. True density refers to the actual mass of a solid substance per unit volume when the material is in an absolutely dense state, that is, the density after removing the internal voids or voids between particles. Generally, a true density analyzer can be used to measure the actual volume and true density of a sample. The true density analyzer uses the Archimedean principle of gas expansion displacement and the Bohr law of small molecular diameter inert gas under certain conditions to accurately measure the true volume of the sample by measuring the volume of the gas discharged from the sample in the test chamber.

[0128] In some implementations, when measuring porosity by the true density method, the sample to be tested is first prepared. For example, a pole piece with only the first layer 550 on the surface can be obtained, and then the sample is placed in a true density detector. Helium is used as the medium gas. After the measuring chamber in the true density detector is gradually pressurized to a preset value, helium is introduced into the expansion chamber. The equilibrium pressure in the two chambers during the experiment is automatically recorded by the instrument, and the real volume V1 of the sample is calculated according to Bohr's law. Then, the apparent volume V2 of the sample is measured. The apparent volume V2 can be calculated by measuring the thickness of the sample and the area of ​​the surface perpendicular to the thickness direction of the sample. Secondly, the difference between the apparent volume V2 and the real volume V1 can be further calculated, and the porosity of the sample can be characterized by the ratio of the difference to the real volume V1 of the sample. It should also be understood that in the embodiment of the present application, the real volume V1 of the sample can be measured multiple times by the true density detector, and the porosity of the sample can be calculated by taking the average value of the multiple real volumes V1.

[0129] In an embodiment of the present application, the first current collector 510 includes a first body, a first conductive layer 560 is provided on the surface of the coated area 520 of the first body, a first layer 550 is provided in the edge area 530 of the first body, and the porosity of the first layer 550 is less than the porosity of the first conductive layer 560, that is, the density of the first layer 550 is higher than the density of the first conductive layer 560, and the problem of powder falling of the electrode to be cut during the cutting of the edge area 530 can be improved by improving the density of the first layer 550, thereby reducing the risk of internal short circuit of the battery cell 20 caused by overlapping of the positive electrode plate 502 and the negative electrode plate 501, thereby improving the yield rate of the battery cell 20.

[0130] It should be understood that in the embodiment of the present application, when the first layer 550 is coated on the surface of the above-mentioned edge area 530, the following methods are included but not limited to: first, the first layer 550 is directly coated on the surface of the edge area 530, and the porosity of the first layer 550 is less than the porosity of the first conductive layer 560 coated on the surface of the coating area 520, and the thickness of the first layer 550 can be greater than, equal to or less than the thickness of the first conductive layer 560, and the porosity of the first layer 550 on the obtained pole piece 50 is less than the porosity of the first conductive layer 550; second, the first layer 550 is first coated on the surface of the edge area 530, the porosity of the first layer 550 is equal to the porosity of the first conductive layer 560, and the thickness of the first layer 550 is greater than or equal to the thickness of the first conductive layer 560, and then the first layer 550 is compacted so that the porosity of the first layer 550 on the edge area 530 after compaction is less than the porosity of the first conductive layer 550.

[0131] In some implementations, the porosity A1 of the first layer 550 satisfies: 0%<A1≤50%.

[0132] It should be understood that in the embodiment of the present application, the porosity A1 of the first layer 550 refers to the percentage between the void volume in the material corresponding to the first layer 550 and the total volume of the material in the natural state. The higher the porosity of the material, the lower its density. It should also be understood that the porosity A1 in the embodiment of the present application can also be referred to as porosity. Specifically, the method for calculating the porosity A1 of the first layer 550 includes but is not limited to the true density method, the buoyancy method, the gas permeation method, the image analysis method, the specific surface area method, and the adsorption method.

[0133] Exemplarily, the porosity A1 of the first layer 550 in the embodiment of the present application may be: 2%, 4%, 6%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%, or its value is within the range obtained by combining any two of the above values.

[0134] In an embodiment of the present application, the porosity A1 of the first layer 550 is less than the porosity of the first conductive layer 560, and the porosity A1 of the first layer is set to 0%<A1≤50%. This can effectively improve the problem of powder loss of the electrode to be cut during the cutting of the edge area 530 by increasing the density of the first layer 550, thereby reducing 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, thereby improving the yield rate of the battery cell 20.

[0135] In some other implementations, the porosity A1 of the first layer 550 satisfies: 20%≤A1≤30%.

[0136] Illustratively, the porosity A1 of the first layer 550 in the embodiment of the present application may be: 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%, or its value is within the range obtained by combining any two of the above values.

[0137] In an embodiment of the present application, the porosity A1 of the first layer 550 is less than the porosity of the first conductive layer 560, and the porosity A1 of the first layer 550 is set to 20%≤A1≤30%. This can further improve the problem of powder loss of the electrode to be cut during the cutting of the edge area 530 by increasing the density of the first layer 550, thereby reducing the risk of internal short circuit in the battery cell 20 caused by overlap between the positive electrode sheet 502 and the negative electrode sheet 501, thereby improving the yield rate of the battery cell 20.

[0138] In some implementations, the ratio L1 / D1 between the dimension L1 of the edge region 530 along the first direction and the thickness D1 of the first conductive layer 560 satisfies: 10≤L1 / D1≤1000, preferably, 20≤L1 / D1≤100, wherein the first direction is perpendicular to the thickness direction of the pole piece 50. Exemplarily, in the embodiment of the present application, the first direction may be direction Y or direction X.

[0139] Exemplarily, the ratio L1 / D1 between the dimension L1 of the edge area 530 along the first direction and the thickness D1 of the first conductive layer 560 in the embodiment of the present application may be: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900 or 1000, or its value is within the range obtained by combining any two of the above values.

[0140] In the embodiment of the present application, by setting the ratio L1 / D1 between the dimension L1 of the edge area 530 along the first direction and the thickness D1 of the first conductive layer 560 to 10≤L1 / D1≤1000, and preferably, the value of L1 / D1 can also be set to 20≤L1 / D1≤100, the thermal impact on the first conductive layer 560 during the laser die-cutting process can be reduced, and the powder loss problem of the pole piece 50 caused by the thermal expansion of the first conductive layer 560 during the cutting process can be reduced, thereby improving the manufacturing performance of the battery 10.

[0141] In some implementations, the dimension L1 of the edge region 530 along the first direction satisfies: 2 mm ≤ L1 ≤ 20 mm. For example, in the embodiment of the present application, the first direction may be direction Y or direction X.

[0142] It should be understood that in the embodiments of the present application, Figure 4 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.

[0143] Exemplarily, the dimension L1 of the edge area 530 along the first direction in the embodiment of the present application may be: 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 12mm, 14mm, 16mm, 18mm or 20mm, or its value is within the range obtained by combining any two of the above values.

[0144] In the embodiment of the present application, by setting the dimension L1 of the edge area 530 along the first direction to 2mm≤L1≤20mm, the dimension of the coating area 520 along the first direction is adjusted by adjusting the dimension L1 of the edge area 530 along the first direction, so as to improve the conductivity of the first conductive layer 560 and thus improve the energy density of the battery 10.

[0145] In some other implementations, the dimension L1 of the edge region 530 along the first direction satisfies: 3mm≤L1≤6mm. For example, in the embodiment of the present application, the first direction may be direction Y or direction X.

[0146] Exemplarily, the dimension L1 of the edge area 530 along the first direction in the embodiment of the present application may be: 3mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4mm, 4.2mm, 4.4mm, 4.6mm, 4.8mm, 5mm, 5.2mm, 5.4mm, 5.6mm, 5.8mm or 6mm, or its value is within the range obtained by combining any two of the above values.

[0147] In the embodiment of the present application, by setting the dimension L1 of the edge area 530 along the first direction to 3mm≤L1≤6mm, the dimension L1 of the edge area 530 along the first direction is adjusted to further improve the conductivity of the first conductive layer 560, thereby improving the energy density of the battery 10.

[0148] In some implementations, the thickness D1 of the first conductive layer 560 satisfies: 1 μm≤D1≤50 μm.

[0149] Exemplarily, the thickness D1 of the first conductive layer 560 may be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm, or its value is within the range obtained by combining any two of the above values.

[0150] In the embodiment of the present application, by setting the thickness D1 of the first conductive layer 560 to 1 μm≤D1≤50 μm, the conductivity of the first conductive layer 560 can be improved by controlling the thickness D1 of the first conductive layer 560 , thereby improving the energy density of the battery 10 .

[0151] In some implementations, the material of the first conductive layer 560 includes at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon. Thus, in the embodiment of the present application, by setting the material of the first conductive layer 560 to at least one of the following materials: carbon nanotubes, graphene, conductive graphite, and conductive carbon, the conductive performance of the pole piece 50 can be improved, thereby improving the energy density of the battery 10.

[0152] 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. For example, 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 .

[0153] In some implementations, such as Figure 6 and Figure 7 As shown, the first layer 550 extends to the tab region 540 .

[0154] It should be understood that in the embodiment of the present application, the first layer 550 extending to the tab region 540 means that the first layer 550 can be disposed on at least one of the two surfaces of the tab region 540 in a thickness direction perpendicular to the tab region 540. It should also be understood that the first layer 550 can be disposed in at least a portion of the tab region 540.

[0155] In the embodiment of the present application, by extending the first layer 550 to the pole lug area 540, that is, the first layer 550 can be arranged on at least a portion of the surface of the pole lug area 540, the pole lug area 540 can be strengthened to reduce the deformation and cracking of the pole piece 50 during the cutting process and the subsequent winding process, thereby improving the performance of the battery 10, and facilitating the processing and manufacturing of the pole piece 50, thereby improving the manufacturing performance of the battery 10.

[0156] In some implementations, such as Figure 7 As shown, the first layer 550 also extends to the surface of the first conductive layer 560 away from the first current collector 510. Thus, in the embodiment of the present application, by extending the first layer 550 to the surface of the first conductive layer 560 away from the first current collector 510, the processing and manufacturing of the pole piece 50 is facilitated, thereby improving the manufacturing performance of the battery 10.

[0157] In some implementations, the first layer 550 includes a second conductive layer.

[0158] It should be understood that in the embodiment of the present application, the porosity of the second conductive layer is smaller than the porosity of the first conductive layer 560, that is, the density of the second conductive layer is greater than the density of the first conductive layer 560, and the second conductive layer can be arranged on at least one of the two surfaces of the edge region 530 in a thickness direction perpendicular to the edge region 530.

[0159] It should be understood that in the embodiments of the present application, Figure 5 and Figure 7 The thickness of the second conductive layer can be represented by D2.

[0160] In the embodiment of the present application, by providing a second conductive layer on the surface of the edge region 530 , the deposition area of ​​metal ions on the electrode 50 can be increased, thereby improving the conductive performance of the electrode 50 and increasing the energy density of the battery 10 .

[0161] In some implementations, the material of the second conductive layer includes at least one of the following materials: carbon nanotubes, graphene, and conductive graphite. Thus, in the embodiment of the present application, by setting the material of the second conductive layer to at least one of the following materials: carbon nanotubes, graphene, and conductive graphite, the conductive performance of the pole piece 50 can be significantly improved, thereby improving the energy density of the battery 10.

[0162] In some implementations, when the material of the second conductive layer includes at least one of the following materials: carbon nanotubes, graphene, and conductive graphite, the thickness D2 of the second conductive layer satisfies: 2μm≤D2≤150μm, preferably, 70μm≤D2≤120μm.

[0163] Exemplarily, the thickness D2 of the second conductive layer in the embodiment of the present application may be: 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 15μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm or 150μm, or its value is within the range obtained by combining any two of the above values.

[0164] In an embodiment of the present application, when the material of the second conductive layer includes at least one of the following materials: carbon nanotubes, graphene, and conductive graphite, by setting the thickness D2 of the second conductive layer to 2μm≤D2≤150μm, preferably, the thickness D2 of the second conductive layer can also be set to: 70μm≤D2≤120μm, the conductivity of the second conductive layer can be improved by controlling the thickness D2 of the second conductive layer, thereby improving the energy density of the battery 10.

[0165] In some implementations, the material of the second conductive layer includes conductive carbon, and the thickness D2 of the second conductive layer satisfies: 10 μm≤D2≤70 μm.

[0166] Exemplarily, the thickness D2 of the second conductive layer in the embodiment of the present application may be: 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 25μm, 30μm, 40μm, 50μm, 60μm or 70μm, or its value is within the range obtained by combining any two of the above values.

[0167] It should be understood that in the embodiment of the present application, when the material of the second conductive layer is set to conductive carbon, after the conductive carbon is coated on the surface of the pole piece 50, since the conductive carbon is a fluffy structure with a large porosity, it is also necessary to perform a compaction process on it to reduce the porosity of the second conductive layer. In some implementations, when the porosity of the second conductive layer is smaller than the porosity of the first conductive layer 560, the thickness D2 of the second conductive layer can be greater than, less than, or equal to the thickness D1 of the first conductive layer 560.

[0168] In the embodiment of the present application, when the material of the second conductive layer is set to conductive carbon, since the conductive carbon is a fluffy structure with a large porosity, compaction treatment is required after the second conductive layer is coated on the edge area to reduce the porosity of the second conductive layer. Secondly, by setting the thickness D2 of the second conductive layer on the surface of the edge area to 10μm≤D2≤70μm, the conductivity of the second conductive layer can be improved by controlling the thickness D2 of the second conductive layer, thereby improving the energy density of the battery.

[0169] In some implementations, such as Figures 4 to 7 As shown, the first layer 550 includes an insulating layer.

[0170] It should be understood that in the embodiment of the present application, the porosity of the insulating layer is smaller than the porosity of the first conductive layer 560, that is, the density of the second insulating layer is greater than the density of the first conductive layer 560, and the insulating layer can be arranged on at least one of the two surfaces of the edge region 530 in a thickness direction perpendicular to the edge region 530.

[0171] In an embodiment of the present application, when cutting the electrode to be cut, an insulating layer is set on the surface of the edge area 530, and the porosity of the insulating layer is less than the porosity of the first conductive layer 560, that is, the density of the insulating layer is higher than the density of the first conductive layer 560. This can effectively improve the problem of powder loss during the cutting process, significantly reduce the risk of internal short circuit of the battery cell 20, and effectively reduce the deposition of metal at the edge of the electrode 50, thereby improving the yield of the battery cell 20.

[0172] It should be understood that in the embodiments of the present application, Figure 5 and Figure 7 As shown, the thickness of the insulating layer can be represented by D3.

[0173] In some implementations, the thickness D3 of the insulating layer satisfies: 5 μm≤D3≤100 μm, preferably, 5 μm≤D3≤20 μm.

[0174] Exemplarily, the thickness D3 of the insulating layer in the embodiment of the present application may be: 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 25μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm, or its value is within the range obtained by combining any two of the above values.

[0175] In the embodiment of the present application, by setting the material of the second conductive layer as an insulating layer, and setting the thickness D3 of the insulating layer to 5μm≤D3≤100μm, preferably, 5μm≤D3≤20μm, the deposition of metal ions at the edge of the pole piece 50 can be reduced by adjusting the thickness D3 of the insulating layer, while facilitating the processing and manufacturing of the pole piece 50 and improving the manufacturing performance of the battery 10.

[0176] In some implementations, the material of the insulating layer includes at least one of the following materials: boehmite, polyvinylidene fluoride, ethylene propylene diene rubber, and polyimide. Thus, in the embodiment of the present application, by setting the material of the insulating layer to at least one of the following materials: boehmite, polyvinylidene fluoride, ethylene propylene diene rubber, and polyimide, the insulation performance of the pole piece 50 in the edge area can be significantly improved, while reducing the deposition of metal ions at the edge of the pole piece 50, while facilitating the processing and manufacturing of the pole piece 50, and improving the manufacturing performance of the battery 10.

[0177] Figure 8 FIG. 2 shows a cross-sectional schematic diagram of a pole piece 50 provided in another embodiment of the present application. Fig. 9FIG. 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 in a direction perpendicular to the thickness of the pole piece 50. Fig. 9 It may be a schematic cross-sectional view of the pole piece 50 in a direction perpendicular to the length 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 in a direction perpendicular to the thickness of the pole piece 50. Fig.11 It may be a schematic cross-sectional view of the pole piece 50 in a direction perpendicular to the length of the pole piece 50 .

[0178] 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.

[0179] For example, Figure 8 and Fig. 9 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 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 .

[0180] In an embodiment of the present application, the edge region 530 includes a first edge region 531, which is connected to a side of the coating region 520 away from the pole lug region 540, and / or the edge region 530 includes a second edge region 532, which is connected between the pole lug 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 porosity of the second conductive layer is less than the porosity of the first conductive layer 560, that is, the density of the second conductive layer is higher than the density of the first conductive layer 560, which can effectively improve the powder falling problem at the edge region 530 during the cutting process of the pole piece to be cut, thereby reducing the risk of internal short circuit in the battery cell 20 due to overlap of the positive pole piece 502 and the negative pole piece 501, thereby improving the yield rate of the battery cell 20.

[0181] 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.

[0182] 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 a separator 503, wherein the separator 503 is disposed between the negative electrode sheet 501 and the positive electrode sheet 502. The positive electrode sheet 502 includes a positive current collector 5021 and an insulating layer 5022 disposed on at least a portion of the surface of the positive current collector 5021.

[0183] 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 5022 is provided at a position of the positive electrode sheet 502 corresponding to the edge area 530 of the negative electrode sheet 501 .

[0184] It should be understood that in the embodiment of the present application, the area where the insulating layer 5022 is arranged on the positive electrode plate 502 corresponding to the edge area 530 of the negative electrode plate 501 can be named as the first area, and the size of the first area along the direction Y can be less than or equal to the size of the edge area 530 on the negative electrode plate 501 along the direction Y.

[0185] In an embodiment of the present application, the electrode sheet 50 is a negative electrode sheet 501, and the electrode assembly 22 also includes a positive electrode sheet 502. An insulating layer 5022 is provided at a 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, 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 due to the provision of the insulating layer 5022, thereby improving the yield rate of the battery cell 20.

[0186] In some implementations, the battery cell 20 is an alkali metal battery cell. For example, the alkali metal in the alkali metal battery cell includes but is not limited to sodium, potassium, and lithium. Thus, in the embodiment of the present application, by setting the battery cell 20 as an alkali metal battery cell, the energy density of the battery 10 and the reliability of the performance can be improved.

[0187] 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.

[0188] 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 .

[0189] 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 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 in a direction perpendicular to the thickness of the electrode piece 60 to be cut. Fig.15 It may be a schematic cross-sectional view of the pole piece 60 to be cut in a direction perpendicular to the length of the pole piece 60 to be cut.

[0190] In some implementations, such as Figures 13 to 15As shown, the preparation method of the pole piece 50 in the embodiment of the present application includes steps 110 to 140, that is, step 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, the second body includes a coating area 520 and a cutting area 620; step 120, coating the surface of the coating area 520 with a first conductive layer 560; step 130, coating the surface of the cutting area 620 with a first layer 550; step 140, cutting in the cutting area 620 to form the pole piece 50 in the above embodiment, wherein the porosity of the first layer 550 is less than the porosity of the first conductive layer 560. It should be understood that in the embodiment of the present application, the order of step 120 and step 130 in the above method is not limited, that is, step 120 can be performed first and then step 130, or step 130 can be performed first and then step 120.

[0191] It should also 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 11 The pole piece 50 is shown in FIG.

[0192] It should also be understood that in some implementations, such as Fig.14 and Fig.15 As 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 610.

[0193] It should also be understood that in the embodiments of the present application, the above Fig.14 and Fig.15 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.

[0194] In an embodiment of the present application, the second current collector 610 includes a second body, a first conductive layer 560 is coated on the surface of the coating area 520, and a first layer 550 is coated on the surface of the cutting area 620. When cutting is performed in the cutting area 620, since the porosity of the first layer 550 is less than the porosity of the first conductive layer 560, that is, the density of the first layer 550 is higher than the density of the first conductive layer 560, the powder falling problem generated by the cutting process of the electrode piece 60 to be cut in the cutting area 620 can be improved by increasing the density of the first layer 550, thereby reducing the risk of internal short circuit in 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.

[0195] In some implementations, such as Fig.16 As shown in FIG. 17 , before cutting in the cutting area 620, the method for preparing the pole piece 50 further includes: coating the first layer 550 on the surface of the area close to the second body of the pole tab forming area 630. Thus, in the embodiment of the present application, by coating the first layer 550 on the surface of the area close to the second body of the pole tab forming area 630, the pole tab forming area 630 can be strengthened to reduce deformation and cracking of the pole piece 60 to be cut during the cutting process and the subsequent winding process, thereby improving the performance of the battery 10.

[0196] In some implementations, such as Fig.16 and Fig.17 As shown, before cutting in the cutting area 620, the preparation method of the pole piece 50 further includes: coating the first layer 550 on the surface of the first conductive layer 560 away from the second current collector 610. In this way, in the embodiment of the present application, by coating the first layer 550 on the surface of the first conductive layer 560 away from the second current collector 610, during the cutting process of the pole piece 60 to be cut, for example, during laser die cutting, the heat effect on the first conductive layer 560 near the cutting area 620 during the laser die cutting process can be reduced, and the ablation phenomenon occurring at the edge of the cutting position can be reduced, thereby improving the performance of the battery 10.

[0197] In some implementations, such as Figures 14 to 17 As shown, the first layer 550 includes a second conductive layer. Thus, in the embodiment of the present application, by providing the second conductive layer on the surface of the cutting area 620, the deposition area of ​​the metal ions on the target electrode piece can be increased, the conductive performance of the electrode piece 50 can be improved, and thus the energy density of the battery 10 can be improved.

[0198] In some implementations, such as Figures 14 to 17As shown, the first layer 550 includes an insulating layer. Thus, in the embodiment of the present application, by providing an insulating layer on the surface of the cutting area 620, the insulation performance of the pole piece 50 in the edge area can be improved, and the deposition of metal at the edge position of the pole piece 50 can be effectively reduced, thereby improving the yield rate of the battery cell 20.

[0199] In some implementations, such as Figures 14 to 17 As shown, the coating area 520 includes at least two sub-coating areas, and the first sub-cutting area of ​​the cutting area 620 is arranged between the two sub-coating areas. The preparation method of the pole piece 50 also includes: cutting in the first sub-cutting area 621 to form a first edge area on the side of the coating area 520 away from the pole ear forming area 630.

[0200] 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.

[0201] 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 on the side of the coating area 520 away from the tab forming area 630. The first edge area can be the above-mentioned Figure 5 , Figure 7 , Figure 8 and Fig. 9 The first edge region 531 of the pole piece 50 is shown in FIG.

[0202] In an embodiment of the present application, a first sub-cutting area 621 in a cutting area 620 is set between two sub-coating areas, and cutting is performed in the first sub-cutting area 621 to form a first edge area 531 on the side of the coating area 520 away from the tab formation area 630. Since the porosity of the first layer 550 coated on the first sub-cutting area 621 is smaller than the porosity of the first conductive layer 560, that is, the density of the first layer 550 is higher than the density of the first conductive layer 560, the problem of powder falling 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.

[0203] In some implementations, such as Fig.14 and Fig.16As 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 of ​​the target pole piece, and the second edge area is connected between the pole ear area 540 and the coating area 520.

[0204] 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.

[0205] It should also be understood that the second edge region may be the above Figure 5 , Figure 7 , Fig.10 and Fig.11 The second edge region 532 of the pole piece 50 is shown in FIG.

[0206] In an embodiment of the present application, when the electrode piece 60 to be cut is subjected to a cutting process, such as a laser die-cutting process, the die-cutting position is located in the second sub-cutting area 622 between the pole ear forming area 630 and the coating area 520. Since the porosity of the first layer 550 coated on the second sub-cutting area 622 is less than the porosity of the first conductive layer 560, that is, the density of the first layer 550 is higher than the density of the first conductive layer 560, the ablation phenomenon occurring at the die-cutting position of the cutting area 620 during the laser die-cutting process can be reduced by increasing the density of the first layer 550, and the powder falling phenomenon during the cutting process can be reduced, thereby reducing the risk of internal short circuit of the battery cell 20, and thereby improving the yield rate of the battery cell 20.

[0207] In some implementations, see again above Fig.10 and Fig.11, a pole piece 50 is provided, the pole piece 50 comprises: a first current collector 510, a first conductive layer 560 and a first layer 550, the first current collector 510 comprises a first body and a tab region 540 connected to the edge of the first body, the first body comprises a coating region 520 and an edge region 530, the first conductive layer 560 is arranged on the surface of the coating region 520, the first layer 550 is arranged on the surface of the edge region 530, wherein the porosity of the first layer 550 is less than the porosity of the first conductive layer 560, and the porosity A1 of the first layer is 25%, and the dimension L1 of the edge region 530 along the first direction is 5 mm. The edge region 530 comprises a second edge region 532, and the second edge region 532 is connected between the tab region 540 and the coating region 520.

[0208] 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; a first layer, the first layer being disposed on a surface of the edge region; The porosity of the first layer is smaller than the porosity of the first conductive layer.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

24. A method for preparing a pole piece, characterized in that: include: 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; Applying a first layer on the surface of the cutting area; Cutting is performed in the cutting area to form a pole piece as claimed in any one of claims 1 to 18; The porosity of the first layer is smaller than the porosity of the first conductive layer.

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

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

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

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

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

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

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