Current collector, pole piece, electrode assembly, battery monomer, battery and electric device

Abstract

The embodiment of the invention provides a current collector, a pole piece, an electrode assembly, a battery monomer, a battery and an electric device. The pole piece comprises a current collector and an active substance layer, and the active substance layer is coated on the surface of the current collector. The current collector comprises a hole opening area provided with a plurality of through holes, and the active material layer covers the hole opening area. The current collector is provided with the through hole to form the channel for the electrolyte to pass through, so that the infiltration efficiency of the pole piece is improved, the infiltration consistency of the pole piece is improved, and the cycle performance of the battery monomer is improved.

Description

Current collector, pole piece, electrode assembly, battery cell, battery and electrical device Technical Field

[0001] The present application relates to the field of battery technology, and more specifically, to a current collector, a pole piece, an electrode assembly, a battery cell, a battery, and an electrical device. Background Art

[0002] Battery cells are widely used in electronic devices such as mobile phones, laptop computers, electric vehicles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes and power tools, etc.

[0003] In the development of battery technology, how to improve the cycle performance of battery cells is a research direction in battery technology.

[0004] Summary of the Invention

[0005] The present application provides a current collector, a pole piece, an electrode assembly, a battery cell, a battery, and an electrical device, which can improve the cycle performance of the battery cell.

[0006] In a first aspect, an embodiment of the present application provides a current collector for a pole piece, which includes an open area with a plurality of through holes.

[0007] By opening through holes on the current collector, a channel for the electrolyte to pass through is formed, thereby improving the wetting efficiency of the electrode piece, improving the consistency of the wetting of the electrode piece, and improving the cycle performance of the battery cell.

[0008] In some embodiments, the tensile strength of the open area in at least one direction perpendicular to the thickness direction of the current collector is greater than or equal to 100 MPa. The above technical solution can reduce the risk of current collector fracture.

[0009] In some embodiments, the current collector further includes a first non-porous region located to one side of the open region along a first direction; the first non-porous region is free of through-holes. The first direction is perpendicular to the thickness of the current collector. The provision of the first non-porous region increases the distance between the open region and the edge of the current collector along the first direction, reducing the risk of fracture in the open region.

[0010] In some embodiments, the current collector further includes a tab protruding from an edge of the first non-porous region facing away from the non-porous region.

[0011] The first non-porous area separates the tab from the open area, so as to reduce the risk of cutting into the open area during the cutting and forming process of the tab, thereby reducing the risk of the open area being broken.

[0012] In some embodiments, the tensile strength of the open area in the second direction is greater than or equal to 100 MPa. The first direction, the second direction, and the thickness direction are perpendicular to each other. The above technical solution can reduce the risk of the current collector fracturing when the current collector is pulled along the second direction.

[0013] In some embodiments, the tensile strength of the first non-porous region in the second direction is greater than or equal to 500 MPa. The above technical solution can reduce the risk of cracks at the edge of the first non-porous region extending to the open area, thereby reducing the risk of current collector fracture and improving the current collector flow capacity.

[0014] In some embodiments, the tensile strength of the open area in the first direction is greater than or equal to 100 MPa. The above technical solution can reduce the risk of the current collector being broken when the current collector is pulled along the first direction.

[0015] In some embodiments, the current collector further includes a second non-porous region, the second non-porous region being located on a side of the open region facing away from the first non-porous region, and the second non-porous region being free of through-holes. Providing the second non-porous region increases the distance between the open region and the edge of the current collector along the first direction, thereby reducing the risk of fracture in the open region.

[0016] In some embodiments, in the first direction, the size of the open area is W, the size of the first non-porous area is K1, and the size of the second non-porous area is K2. W, K1, and K2 satisfy the following: 3% ≤ K1 / (W+K1+K2) ≤ 32%, and 3% ≤ K2 / (W+K1+K2) ≤ 32%. This technical solution can improve the wetting efficiency of the electrode and reduce the risk of current collector fracture.

[0017] In some embodiments, in the first direction, the size of the first non-porous area is 10 mm to 100 mm. The above technical solution can improve the wetting efficiency of the electrode sheet and reduce the risk of current collector breakage.

[0018] In some embodiments, the total area of ​​the plurality of through-holes is S1, the total area of ​​the opening region is S2, and S1 and S2 satisfy the following: 0.1 ≤ S1 / S2 ≤ 0.7. Limiting the value of S1 / S2 to 0.1-0.7 can improve the electrode sheet's wetting efficiency and reduce the risk of current collector fracture.

[0019] In some embodiments, S1 and S2 satisfy: 0.3≤S1 / S2≤0.7. When 0.3≤S1 / S2≤0.7, the wetting efficiency of the electrode sheet can be better improved and the risk of current collector breakage can be further reduced.

[0020] In some embodiments, the through hole has a diameter of 0.02 mm to 2 mm. The diameter D of the through hole is limited to 0.02 mm to 2 mm to reduce the risk of the current collector being broken and to simplify the molding process of the current collector.

[0021] In some embodiments, the diameter of the through hole is 0.2 mm to 0.5 mm. Limiting D to 0.2 mm to 0.5 mm can reduce the risk of the current collector breaking and further simplify the current collector molding process.

[0022] In some embodiments, the current collector is made of at least one of aluminum, copper, nickel, and steel. Aluminum, copper, nickel, and steel have high tensile strength and excellent electrical conductivity.

[0023] In some embodiments, the current collector is made of stainless steel. The current collector made of stainless steel has high tensile strength and can be provided with more through holes to improve the wettability of the electrode.

[0024] In some embodiments, multiple through-holes are arranged in an array along a first direction and a second direction. The first direction, the second direction, and the thickness direction of the current collector are perpendicular to each other. The uniform distribution of the multiple through-holes improves the consistency of electrode wetting, reduces the difference in tensile strength across the open area, and reduces the risk of current collector fracture.

[0025] In a second aspect, an embodiment of the present application provides a pole piece, which includes a current collector provided in any embodiment of the first aspect and an active material layer, wherein the active material layer is coated on the surface of the current collector and covers the opening area.

[0026] The electrolyte can pass through the opening area and infiltrate the active material layers on both sides of the opening area, thereby improving the wetting efficiency, reducing the wettability difference of the active material layers on both sides of the opening area, improving the consistency of the wetting of the electrode, and improving the cycle performance of the battery cell.

[0027] In some embodiments, the active material layer is coated on the open-porous region, the first non-porous region, and the second non-porous region.

[0028] In some embodiments, the current collector further includes a tab protruding from an edge of the first non-porous region facing away from the non-porous region.

[0029] A first non-porous area is retained between the tab and the opening area to separate the cut edge from the opening area during the tab cutting process, thereby reducing the risk of defects in the cut edge extending to the opening area, thereby reducing the risk of the current collector breaking and improving the current collector's flow capacity.

[0030] In a third aspect, an embodiment of the present application provides an electrode assembly, comprising the electrode provided by any embodiment of the second aspect.

[0031] In a fourth aspect, an embodiment of the present application provides a battery cell, comprising a housing and an electrode assembly provided by any embodiment of the third aspect, wherein the electrode assembly is accommodated in the housing.

[0032] In a fifth aspect, an embodiment of the present application provides a battery comprising a plurality of battery cells provided by any embodiment of the fourth aspect.

[0033] In a sixth aspect, an embodiment of the present application provides an electrical device, comprising a battery cell provided by any embodiment of the fourth aspect, wherein the battery cell is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0035] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0036] FIG2 is a schematic diagram of an explosion of a battery provided in some embodiments of the present application;

[0037] FIG3 is a schematic structural diagram of the battery module shown in FIG2 ;

[0038] FIG4 is an exploded schematic diagram of a battery cell provided in some embodiments of the present application;

[0039] FIG5 is a schematic structural diagram of an electrode assembly of a battery cell provided in some embodiments of the present application;

[0040] FIG6 is a schematic diagram of the structure of a pole piece provided in some embodiments of the present application;

[0041] FIG7 is a schematic cross-sectional view of the electrode piece shown in FIG6 taken along line AA;

[0042] FIG8 is a schematic structural diagram of a current collector in some embodiments of the present application;

[0043] FIG9 is an enlarged schematic diagram of FIG8 at the circle A;

[0044] FIG10 is a schematic structural diagram of current collectors in other embodiments of the present application;

[0045] FIG11 is a schematic structural diagram of a current collector provided in some embodiments of the present application;

[0046] FIG12 is a schematic diagram of the structure of the pole piece provided in some embodiments of the present application.

[0047] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0048] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0049] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0050] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0051] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0052] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0053] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0054] The term "plurality" used in this application refers to two or more (including two).

[0055] In this application, the term "parallel" includes not only the absolutely parallel situation, but also the roughly parallel situation conventionally recognized in engineering; at the same time, "vertical" also includes not only the absolutely vertical situation, but also the roughly vertical situation conventionally recognized in engineering.

[0056] In this application, battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, and the embodiments of this application are not limited thereto. Battery cells may be cylindrical, flat, rectangular, or in other shapes, and the embodiments of this application are not limited thereto.

[0057] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. A battery generally also includes a housing for enclosing the one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0058] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode current collector. Taking lithium-ion batteries as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material layer includes a positive electrode active material. The positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The material of the negative electrode current collector can be copper, and the negative electrode active material layer includes a negative electrode active material. The negative electrode active material can be carbon or silicon. The material of the separator can be PP (polypropylene) or PE (polyethylene).

[0059] In a battery cell, the electrolyte is the ionic conductor that conducts electricity between the positive and negative electrodes. During charge and discharge, it transports lithium ions back and forth between the positive and negative electrodes. The electrolyte significantly impacts the battery cell's charge and discharge performance, cycle life, and temperature range.

[0060] Poor cycling performance of battery cells is often related to poor electrolyte wetting of the electrodes. When electrolyte wetting is poor, the ion transport path becomes longer, hindering the movement of ions between the positive and negative electrodes. Electrodes not exposed to the electrolyte cannot participate in the electrochemical reaction, and the cross-sectional resistance of the battery increases, affecting the rate performance, discharge capacity, and service life of the battery cell.

[0061] The current collector (e.g., the positive or negative electrode current collector) is an integral part of the electrode. It not only carries the active material but also collects the electrons generated by the electrochemical reaction and directs them to the external circuit, thereby converting chemical energy into electrical energy. However, the inventors noted that the electrolyte has difficulty passing through the current collector. In other words, the current collector blocks the flow of the electrolyte, reducing the efficiency of electrolyte infiltration. This results in differences in the wettability of the active material layers on both sides of the current collector, affecting the cycling performance of the battery cell.

[0062] In view of this, an embodiment of the present application proposes a technical solution, which opens a through hole on the current collector to form a channel for the electrolyte to pass through, thereby improving the wetting efficiency of the electrode, improving the consistency of the wetting of the electrode, and improving the cycle performance of the battery cell.

[0063] The pole pieces described in the embodiments of the present application are applicable to battery cells, batteries, and electrical devices using batteries.

[0064] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0065] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0066] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application.

[0067] As shown in FIG1 , a battery 2 is provided inside the vehicle 1. The battery 2 may be provided at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1. For example, the battery 2 may serve as an operating power source for the vehicle 1.

[0068] The vehicle 1 may further include a controller 3 and a motor 4 . The controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of the vehicle 1 during startup, navigation, and driving.

[0069] In some embodiments of the present application, the battery 2 can not only serve as the operating power source of the vehicle 1, but also serve as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0070] FIG2 is a schematic diagram of an explosion of a battery provided in some embodiments of the present application.

[0071] As shown in FIG2 , the battery 2 includes a box body 5 and battery cells (not shown in FIG2 ), and the battery cells are accommodated in the box body 5 .

[0072] The housing 5 is used to house battery cells and can have various structures. In some embodiments, the housing 5 can include a first housing portion 5a and a second housing portion 5b. The first housing portion 5a and the second housing portion 5b overlap each other, and the first housing portion 5a and the second housing portion 5b together define a storage space 5c for accommodating the battery cells. The second housing portion 5b can be a hollow structure with one end open. The first housing portion 5a is a plate-like structure, and the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. The first housing portion 5a and the second housing portion 5b can also be hollow structures with one end open. The open side of the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0073] In order to improve the sealing performance after the first box body 5a and the second box body 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 5a and the second box body 5b.

[0074] Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box body.

[0075] In battery 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections. Multiple battery cells can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire battery module can be housed within housing 5. Alternatively, multiple battery cells can be first connected in series, in parallel, or in a hybrid configuration to form a battery module 6, and then multiple battery modules 6 can be connected in series, in parallel, or in a hybrid configuration to form a single unit housed within housing 5.

[0076] FIG3 is a schematic structural diagram of the battery module shown in FIG2 .

[0077] As shown in FIG3 , in some embodiments, there are multiple battery cells 7, which are first connected in series, in parallel, or in hybrid to form a battery module 6. The multiple battery modules 6 are then connected in series, in parallel, or in hybrid to form a whole and housed in a box.

[0078] The multiple battery cells 7 in the battery module 6 can be electrically connected via a busbar component to achieve parallel connection, series connection, or mixed connection of the multiple battery cells 7 in the battery module 6 .

[0079] The battery cell 7 may be a cylindrical battery cell, a square battery cell, or a battery cell of other shapes.

[0080] FIG4 is an exploded schematic diagram of a battery cell provided in some embodiments of the present application; FIG5 is a structural schematic diagram of an electrode assembly of a battery cell provided in some embodiments of the present application.

[0081] As shown in FIG. 4 and FIG. 5 , a battery cell according to some embodiments of the present application includes a housing 20 and an electrode assembly 10 , wherein the electrode assembly 10 is accommodated in the housing 20 .

[0082] The housing 20 is a hollow structure, forming a chamber within it for accommodating the electrode assembly 10 and the electrolyte. The shape of the housing 20 can be determined based on the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is cylindrical, a cylindrical housing can be used; if the electrode assembly 10 is rectangular, a rectangular housing can be used. Optionally, both the electrode assembly 10 and the housing 20 are cylindrical.

[0083] In some embodiments, the housing 20 includes a shell 21 and an end cover 22 . The shell 21 has an opening. The end cover 22 is connected to the shell 21 and is used to cover the opening.

[0084] The end cap 22 is sealed to the housing 21 to form a sealed space for accommodating the electrode assembly 10 and the electrolyte. In some examples, one end of the housing 21 has an opening, and a single end cap 22 is provided to cover the opening of the housing 21. In other examples, both opposite ends of the housing 21 have openings, and two end caps 22 are provided, each covering the two openings of the housing 21.

[0085] In some embodiments, the electrode assembly 10 includes multiple electrode pieces and a separator 12. Exemplarily, the electrode pieces are provided in a plurality, including a first electrode piece 11a and a second electrode piece 11b of opposite polarity. The separator 12 is used to insulate the first electrode piece 11a from the second electrode piece 11b. The electrode assembly 10 primarily operates by the movement of metal ions between the first electrode piece 11a and the second electrode piece 11b.

[0086] One of the first electrode piece 11 a and the second electrode piece 11 b is a positive electrode piece, and the other of the first electrode piece 11 a and the second electrode piece 11 b is a negative electrode piece.

[0087] In some embodiments, the first pole piece 11a, the second pole piece 11b, and the separator 12 are all strip-shaped structures, and the first pole piece 11a, the second pole piece 11b, and the separator 12 are wound together around a central axis to form a wound structure. The wound structure can be a cylindrical structure, a flat structure, or a structure of other shapes.

[0088] In some embodiments, the battery cell 7 further includes an electrode terminal 30 disposed in the housing 20 and configured to electrically connect to the electrode assembly 10 to conduct the electrical energy generated by the electrode assembly 10. For example, at least a portion of the electrode terminal 30 is exposed to the exterior of the housing 20 to enable electrical connection to other structures (e.g., a busbar).

[0089] FIG6 is a schematic diagram of the structure of a pole piece provided in some embodiments of the present application; FIG7 is a schematic cross-sectional view of the pole piece shown in FIG6 taken along line AA.

[0090] As shown in FIG. 6 and FIG. 7 , an embodiment of the present application provides a pole piece 11 , which includes a current collector 111 and an active material layer 112 coated on a surface of the current collector 111 .

[0091] The electrode piece 11 of this embodiment can be a positive electrode piece in an electrode assembly, or a negative electrode piece in an electrode assembly.

[0092] The active material layer 112 can be applied to one surface of the current collector 111 or to both surfaces of the current collector 111. The active material layer 112 can be used to generate an electrochemical reaction with the electrolyte to generate an electric current. The current collector 111 can collect the generated electric current and guide the electric current to an external circuit.

[0093] As shown in FIG6 , the active material layer 112 may be partially located in the through hole 113 . It is understandable that the active material layer 112 may not be located in the through hole 113 .

[0094] The active material layer 112 of the positive electrode sheet may include lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganese oxide or other active materials. The active material layer 112 of the negative electrode sheet may include carbon, silicon or other active materials.

[0095] FIG8 is a schematic diagram of the structure of the current collector of some embodiments of the present application; FIG9 is an enlarged schematic diagram of the circle A in FIG8 .

[0096] 6 to 9 , an embodiment of the present application provides a current collector 111 for a pole piece 11 . The current collector 111 includes an open area 1111 having a plurality of through holes 113 .

[0097] The through hole 113 penetrates the current collector 111 along the thickness direction Z of the current collector 111 .

[0098] The through hole 113 may be a circular hole, a square hole, a triangular hole, a waist hole or a hole in other shapes.

[0099] The current collector 111 is conductive. The present embodiment does not limit the material of the current collector 111. For example, the current collector 111 can be a metal foil or a multi-layer composite structure formed by metal and plastic.

[0100] On the current collector 111, the plurality of through-holes 113 can be evenly distributed according to a predetermined pattern; for example, the plurality of through-holes 113 can be distributed in a rectangular array or a circular array. In some examples, the plurality of through-holes 113 are arranged in multiple rows, and the through-holes 113 in two adjacent rows can be aligned or staggered. Alternatively, the plurality of through-holes 113 can be irregularly distributed on the current collector 111.

[0101] The opening area 1111 can be defined by the boundaries of the outermost through-holes 113. For example, when the distribution range of the plurality of through-holes 113 is rectangular, the opening area 1111 can be the smallest rectangle that can contain all of the through-holes 113. When the distribution range of the plurality of through-holes 113 is circular, the opening area 1111 can be the smallest circle that can contain all of the through-holes 113. When the distribution range of the plurality of through-holes 113 is irregular, the common tangent of the outermost through-holes 113 serves as the boundary of the opening area 1111.

[0102] In the embodiment of the present application, a through hole 113 is opened on the current collector 111 to form a channel for the electrolyte to pass through, thereby improving the wetting efficiency of the electrode 11, improving the consistency of the wetting of the electrode 11, and improving the cycle performance of the battery cell.

[0103] In some embodiments, the tensile strength of the open area 1111 in at least one direction perpendicular to the thickness direction Z of the current collector 111 is greater than or equal to 100 MPa.

[0104] Tensile strength, also known as ultimate tensile strength, characterizes a material's resistance to maximum uniform plastic deformation. Before a tensile specimen is subjected to maximum tensile stress, deformation is uniform and consistent. However, beyond this stress, the material begins to neck, resulting in concentrated deformation. For brittle materials with no (or minimal) uniform plastic deformation, tensile strength reflects the material's resistance to fracture. For metals, tensile strength is the critical value at which the metal transitions from uniform plastic deformation to locally concentrated plastic deformation, and is also the metal's maximum load-bearing capacity under static tension.

[0105] The open area 1111 may have a tensile strength greater than or equal to 100 MPa in only one direction. Alternatively, the open area 1111 may have a tensile strength greater than or equal to 100 MPa in multiple directions. Optionally, the tensile strength of the open area 1111 may be greater than or equal to 100 MPa in any direction perpendicular to the thickness direction Z.

[0106] During the production process of the electrode sheet 11, the electrode sheet 11 needs to go through multiple processes such as coating, rolling, and cutting. For example, in the coating process, the active material layer 112 is applied to the surface of the current collector 111; in the rolling process, the active material layer 112 can be rolled to compact the active material layer 112; in the cutting process, the current collector 111 can be cut to form the electrode tabs 1112a of the electrode sheet 11.

[0107] During various steps, the current collector 111 is subjected to stretching. To reduce the risk of breakage, the current collector 111 must meet certain tensile strength requirements. The inventors noted that providing through-holes 113 in the current collector 111 reduces the tensile strength of the perforated area 1111. Insufficient tensile strength in the perforated area 1111 increases the risk of breakage, impacting product quality.

[0108] After in-depth research and numerous experiments, the inventors discovered that by setting the tensile strength of the opening region 1111 in the direction of greater tensile force to be greater than or equal to 100 MPa, the risk of the current collector 111 breaking can be reduced.

[0109] Illustratively, the tensile strength of the opening area 1111 can be measured in the following manner: Ⅰ) Cut a rectangular specimen from the opening area 1111, where the length, width, and thickness of the specimen are U1, U2, and U3, respectively; Ⅱ) Place the specimen on a tensile testing machine, with both ends of the specimen along the length direction fixed on the clamps of the tensile testing machine; Ⅲ) Turn on the tensile testing machine, which stretches the specimen at a set speed (e.g., 50 mm / min), and record the force corresponding to the fracture of the specimen as F (unit N); Ⅳ) The tensile strength of the specimen along the length direction is P = F / (U2×U3).

[0110] In some embodiments, the current collector 111 further includes a first non-porous region 1112 , which is located on one side of the open region 1111 along the first direction X. The first non-porous region 1112 is not provided with a through hole 113 . The first direction X is perpendicular to the thickness direction Z of the current collector 111 .

[0111] The edges of the current collector 111 are prone to defects, which can worsen and produce microcracks when the current collector 111 is pulled. If the distance between the opening region 1111 and the edge of the current collector 111 is too small, the microcracks may extend to the through-hole 113, thereby causing the entire opening region 1111 to break.

[0112] In the embodiment of the present application, by providing the first non-porous region 1112 , the distance between the open region 1111 and the edge of the current collector 111 along the first direction X can be increased, thereby reducing the risk of breakage of the open region 1111 .

[0113] In some embodiments, the current collector 111 further includes a tab 1112 a , which protrudes from an edge of the first non-porous region 1112 facing away from the non-porous region 1111 .

[0114] The tab 1112 a is used to be electrically connected to the electrode terminal to lead out the current collected by the current collector 111 .

[0115] In the embodiment of the present application, the first non-porous area 1112 separates the tab 1112a from the opening area 1111 to reduce the risk of cutting into the opening area 1111 during the cutting and forming process of the tab 1112a, thereby reducing the risk of the opening area 1111 being broken.

[0116] In some embodiments, the tab 1112 a is not provided with a through hole 113 to ensure the flow area and strength of the tab 1112 a and reduce the risk of the tab 1112 a being torn.

[0117] In some embodiments, the tensile strength of the open area 1111 is greater than or equal to 100 MPa in the second direction Y. The first direction X, the second direction Y, and the thickness direction Z are perpendicular to each other.

[0118] Compared to the first direction X, the current collector 111 is more susceptible to tension in the second direction Y. For example, during the production process of the electrode 11, it needs to be tensioned under the action of tension, and the direction of the tension is generally consistent with the second direction Y, which causes the current collector 111 to be subjected to greater tension in the second direction Y.

[0119] The tension on the opening area 1111 in the first direction X is relatively small, and this embodiment does not limit the tensile strength of the opening area 1111 along the first direction X. In other words, the tensile strength of the opening area 1111 in the first direction X may be greater than, less than, or equal to 100 MPa.

[0120] In the embodiment of the present application, the tensile strength of the open area 1111 in the second direction Y is greater than or equal to 100 MPa, which can reduce the risk of breakage of the current collector 111.

[0121] Exemplarily, the first direction X and the second direction Y are two directions of the flattened current collector 111. Optionally, the first direction X is the width direction of the flattened current collector 111, and the second direction Y is the length direction of the flattened current collector 111.

[0122] In some embodiments, in the second direction Y, the tensile strength of the first non-porous region 1112 is greater than or equal to 500 MPa.

[0123] The edges of the first non-porous region 1112 are susceptible to defects during the molding process. When the first non-porous region 1112 is stretched in the second direction Y, there is a risk of further defects. Insufficient tensile strength in the first non-porous region 1112 may lead to cracking in the first non-porous region 1112. If the first non-porous region 1112 cracks, the resulting cracks may extend to the porous region 1111, further causing the current collector 111 to break.

[0124] After in-depth research and numerous experiments, the inventors found that by setting the tensile strength of the first non-porous region 1112 in the second direction Y to be greater than or equal to 500 MPa, the risk of fracture of the current collector 111 can be reduced and the flow capacity of the current collector 111 can be improved.

[0125] In some embodiments, in the first direction X, the tensile strength of the open area 1111 is greater than or equal to 100 MPa.

[0126] The embodiment of the present application can reduce the risk of the current collector 111 being broken when the current collector 111 is pulled along the first direction X.

[0127] In some embodiments, the current collector 111 further includes a second non-porous region 1113 , which is located on a side of the open region 1111 away from the first non-porous region 1112 , and no through-holes 113 are provided in the second non-porous region 1113 .

[0128] The edges of the current collector 111 are prone to defects, which can worsen and produce microcracks when the current collector 111 is pulled. If the distance between the opening region 1111 and the edge of the current collector 111 is too small, the microcracks may extend to the through-hole 113, thereby causing the entire opening region 1111 to break.

[0129] In the embodiment of the present application, by providing the second non-porous region 1113 , the distance between the open region 1111 and the edge of the current collector 111 along the first direction X can be increased, thereby reducing the risk of breakage of the open region 1111 .

[0130] In some embodiments, in the second direction Y, the tensile strength of the second non-porous region 1113 is greater than or equal to 500 MPa.

[0131] In some embodiments, the total area of ​​the plurality of through holes 113 is S1, the total area of ​​the opening region 1111 is S2, and S1 and S2 satisfy: 0.1≤S1 / S2≤0.7.

[0132] The larger the value of S1 / S2, the easier it is for the electrolyte to pass through the opening area 1111, the more significantly the through-hole 113 improves the wetting efficiency of the electrode 11, and the better the consistency of the wetting of the electrode 11. However, the larger the value of S1 / S2, the lower the tensile strength of the opening area 1111, and the more likely the current collector 111 is to break during the molding process.

[0133] The smaller the value of S1 / S2, the higher the tensile strength of the opening region 1111, and the lower the risk of fracture of the current collector 111 during the molding process. However, the smaller the value of S1 / S2, the more difficult it is for the electrolyte to pass through the opening region 1111, and the less effective the through-hole 113 is in improving the wetting efficiency of the electrode 11.

[0134] After in-depth research and numerous experiments, the inventors discovered that limiting the value of S1 / S2 to 0.1-0.7 can improve the wetting efficiency of the electrode 11 and reduce the risk of the current collector 111 breaking.

[0135] Optionally, the value of S1 / S2 is 0.1, 0.3, 0.5, 0.6 or 0.7.

[0136] In some embodiments, S1 and S2 satisfy: 0.3≤S1 / S2≤0.7.

[0137] After in-depth research and numerous experiments, the inventors found that when 0.3≤S1 / S2≤0.7, the wetting efficiency of the pole piece 11 can be better improved and the risk of the current collector 111 breaking can be further reduced.

[0138] In some embodiments, the diameter D of the through hole 113 is 0.02 mm-2 mm.

[0139] The through hole 113 may be a circular hole, a square hole or a hole of other shapes. When the through hole 113 is a non-circular hole, the hole diameter may be the diameter of the circumscribed circle of the through hole 113 .

[0140] Given a given total area of ​​through-holes 113 in opening region 1111, a smaller diameter D of through-holes 113 requires more through-holes 113, a more complex process for opening holes in current collector 111, and a lower efficiency in forming current collector 111. Given a given total area of ​​through-holes 113 in opening region 1111, a larger diameter D of through-holes 113 increases the likelihood of stress concentration around through-holes 113, making the opening region more susceptible to deformation and fracture under tension.

[0141] In addition, when the active material layer 112 is coated, the active material layer 112 can be maintained on the current collector 111 under its own tension; if the aperture D of the through hole 113 is too large, the active material layer 112 may pass through the through hole 113 and leak, resulting in waste of active material.

[0142] After in-depth research and numerous experiments, the inventors discovered that limiting the aperture D of the through hole 113 to 0.02 mm-2 mm can reduce the risk of breakage of the current collector 111 and simplify the molding process of the current collector 111 .

[0143] Optionally, the aperture D of the through hole 113 is defined at 0.02 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.5 mm, 1 mm, 1.5 mm or 2 mm.

[0144] In some embodiments, the diameter of the through hole 113 is 0.2 mm to 0.5 mm. After in-depth research and extensive experiments, the inventors found that limiting D to 0.2 mm to 0.5 mm can reduce the risk of breakage of the current collector 111 and further simplify the molding process of the current collector 111.

[0145] In some embodiments, the material of the current collector 111 is selected from at least one of aluminum, copper, nickel, and steel.

[0146] For example, the current collector 111 may be aluminum foil, copper foil, nickel foil, or steel foil. Alternatively, the current collector 111 may be formed by laminating at least two of aluminum foil, copper foil, nickel foil, and steel foil.

[0147] Aluminum, copper, nickel, and steel have high tensile strength and excellent electrical conductivity.

[0148] In some embodiments, the current collector 111 is made of stainless steel. The current collector 111 made of stainless steel has high tensile strength and can be provided with more through holes 113 to improve the wettability of the electrode 11 .

[0149] In some embodiments, the plurality of through holes 113 are arranged in an array along a first direction X and a second direction Y. The first direction X, the second direction Y, and a thickness direction Z of the current collector 111 are perpendicular to each other.

[0150] Exemplarily, the opening area 1111 includes a plurality of rows of through holes 113 equidistantly arranged along the first direction X, and the plurality of through holes 113 in each row of through holes 113 are equidistantly arranged along the second direction Y.

[0151] In the embodiment of the present application, the multiple through holes 113 are evenly distributed, which can improve the consistency of the wetting of the electrode 11, reduce the difference in tensile strength of the opening area 1111, and reduce the risk of fracture of the current collector 111.

[0152] Evenly distributing the plurality of through holes 113 can also reduce the difficulty of forming.

[0153] In some embodiments, the aperture area 1111 is substantially rectangular. For example, the aperture area 1111 includes a first boundary 1111a and a second boundary 1111b disposed opposite each other along a first direction X. The first boundary 1111a extends along a second direction Y and connects to the first non-porous area 1112. The second boundary 1111b extends along the second direction Y and connects to the second non-porous area 1113.

[0154] The first boundary 1111 a is tangent to a row of through holes 113 adjacent to the first non-porous region 1112 , and the second boundary 1111 b is tangent to a row of through holes 113 adjacent to the second non-porous region 1113 .

[0155] The embodiment of the present application further provides a pole piece 11 , which includes a current collector 111 and an active material layer 112 according to any of the aforementioned embodiments. The active material layer 112 is coated on the surface of the current collector 111 and covers the opening area 1111 .

[0156] The electrolyte can pass through the opening area 1111 and infiltrate the active material layer 112 on both sides of the opening area 1111, thereby improving the wetting efficiency, reducing the wettability difference of the active material layer 112 on both sides of the opening area 1111, improving the consistency of the wetting of the electrode 11, and improving the cycle performance of the battery cell.

[0157] In some embodiments, the current collector 111 includes an open-porous region 1111 , a first non-porous region 1112 , and a second non-porous region 1113 . Both the first non-porous region 1112 and the second non-porous region 1113 are coated with an active material layer 112 .

[0158] Compared to the active material layer 112 coated on the middle portion of the current collector 111, the active material layer 112 coated on both ends of the current collector 111 is more susceptible to electrolyte infiltration. Therefore, the through holes 113 may not be provided on both ends of the current collector 111, that is, the first non-porous region 1112 and the second non-porous region 1113 are retained to ensure the strength of the current collector 111 and reduce the risk of breakage of the current collector 111.

[0159] It is difficult for the electrolyte to infiltrate the active material layer 112 coated in the middle of the current collector 111. Therefore, in the embodiment of the present application, a through hole 113 is opened in the middle of the current collector 111 to form an open area 1111, so as to improve the wetting efficiency of the electrolyte in the active material layer 112 coated in the middle of the current collector 111, improve the consistency of the wetting of the electrode 11, and improve the cycle performance of the battery cell.

[0160] In some embodiments, the current collector 111 further includes a tab 1112 a , at least a portion of which is not coated with the active material layer 112 .

[0161] In some embodiments, the tab 1112 a protrudes from an edge of the first non-porous region 1112 facing away from the porous region 1111 .

[0162] There may be one or more tabs 1112a. For example, there may be more tabs 1112a, which are spaced apart along the second direction Y.

[0163] In the embodiment of the present application, a first non-porous area 1112 is retained between the pole tab 1112a and the opening area 1111 to separate the cut edge from the opening area 1111 during the process of cutting the pole tab 1112a, thereby reducing the risk of defects in the cut edge extending to the opening area 1111, thereby reducing the risk of the current collector 111 breaking and improving the flow capacity of the current collector 111.

[0164] In some embodiments, in the first direction X, the size of the apertured area 1111 is W, the size of the first non-apertured area 1112 is K1, and the size of the second non-apertured area 1113 is K2. W, K1, and K2 satisfy the following conditions: 3% ≤ K1 / (W+K1+K2) ≤ 32%, and 3% ≤ K2 / (W+K1+K2) ≤ 32%.

[0165] For example, a sample having a size E along the second direction Y is cut from the current collector 111, and both edges of the sample along the second direction Y are parallel to the first direction X. W may be the ratio of the total area of ​​the open area 1111 to E, K1 may be the ratio of the total area of ​​the first non-porous area 1112 to E, and K2 may be the ratio of the total area of ​​the first non-porous area 1112 to E. Optionally, when cutting the sample, the value of E may be greater than W + K1 + K2.

[0166] Defects are likely to occur in the first non-porous region 1112 and the second non-porous region 1113 away from the edge of the porous region 1111 . When the current collector 111 is pulled, the defects may worsen and generate microcracks.

[0167] The smaller K1 / (W+K1+K2), the smaller the distance between the edge of the first non-porous region 1112 and the open area 1111. When the current collector 111 is pulled, the risk of microcracks in the first non-porous region 1112 extending to the through-hole 113 increases, and the risk of the current collector 111 fracturing also increases. The larger K1 / (W+K1+K2), the smaller the area of ​​the open area 1111, the more difficult it is for the electrolyte to pass through the open area 1111, and the less improvement in the wetting efficiency of the electrode sheet 11 by the through-hole 113.

[0168] Similarly, the smaller K2 / (W+K1+K2), the smaller the distance between the edge of the second non-porous region 1113 and the open hole region 1111. When the current collector 111 is pulled, the risk of microcracks in the second non-porous region 1113 extending to the through-hole 113 increases, and the risk of the current collector 111 fracturing also increases. The larger K2 / (W+K1+K2), the smaller the area of ​​the open hole region 1111, the more difficult it is for the electrolyte to pass through the open hole region 1111, and the less improvement in the wetting efficiency of the electrode sheet 11 by the through-hole 113.

[0169] After in-depth research and numerous experiments, the inventors found that limiting K1 / (W+K1+K2) to 3%-32% and limiting K2 / (W+K1+K2) to 3%-32% can improve the wetting efficiency of the electrode 11 and reduce the risk of breakage of the current collector 111.

[0170] In some embodiments, in the first direction X, a dimension K1 of the first imperforate area 1112 is 10 mm-100 mm.

[0171] The smaller K1 is, the smaller the distance between the edge of the first non-porous region 1112 and the open area 1111 is. When the current collector 111 is pulled, the risk of microcracks in the first non-porous region 1112 extending to the through-hole 113 increases, and the risk of the current collector 111 fracturing also increases. The larger K1 is, the smaller the area of ​​the open area 1111 is, the more difficult it is for the electrolyte to pass through the open area 1111, and the less improvement in the wetting efficiency of the electrode 11 by the through-hole 113 is.

[0172] After in-depth research and numerous experiments, the inventors discovered that limiting K1 to 10 mm-100 mm can improve the wetting efficiency of the pole piece 11 and reduce the risk of the current collector 111 breaking.

[0173] In some embodiments, in the first direction X, a dimension K2 of the second imperforate area 1113 is 10 mm-100 mm.

[0174] FIG10 is a schematic structural diagram of current collectors according to other embodiments of the present application.

[0175] As shown in FIG10 , in some embodiments, the plurality of through holes 113 are arranged along a first direction X and a second direction Y. The first direction X, the second direction Y, and the thickness direction Z of the current collector 111 are perpendicular to each other.

[0176] In some embodiments, the opening area 1111 includes multiple rows of through holes 113 equidistantly arranged along the first direction X. The through holes 113 in two adjacent rows may be staggered in the second direction Y.

[0177] According to some embodiments of the present application, the present application also provides an electrode assembly, comprising the electrode piece of any of the above embodiments.

[0178] According to some embodiments of the present application, the present application further provides a battery cell, comprising a housing and an electrode assembly according to any of the above embodiments, wherein the electrode assembly is accommodated in the housing.

[0179] According to some embodiments of the present application, the present application also provides a battery comprising a plurality of battery cells according to any of the above embodiments.

[0180] According to some embodiments of the present application, the present application further provides an electrical device comprising a battery cell according to any of the above embodiments, the battery cell being used to provide electrical energy to the electrical device. The electrical device may be any of the aforementioned devices or systems using the battery cell.

[0181] 6 to 9 , according to some embodiments of the present application, a pole piece 11 is provided. The pole piece 11 includes a current collector 111 and an active material layer 112 coated on a surface of the current collector 111 .

[0182] The current collector 111 includes an open area 1111, a first non-porous area 1112, a second non-porous area 1113, and a tab 1112a. The first non-porous area 1112 and the second non-porous area 1113 are respectively located on both sides of the open area 1111 along the first direction X. The tab 1112a protrudes from the edge of the first non-porous area 1112 facing away from the open area 1111. The open area 1111 is provided with a plurality of through holes 113, while the first non-porous area 1112 and the second non-porous area 1113 are not provided with a through hole 113.

[0183] The open-porous region 1111 , the first non-porous region 1112 , and the second non-porous region 1113 are coated with the active material layer 112 , and at least a portion of the tab 1112 a is not coated with the active material layer 112 .

[0184] The plurality of through holes 113 are arranged in an array along a first direction X and a second direction Y. The first direction X, the second direction Y, and the thickness direction Z are perpendicular to each other.

[0185] In the second direction Y, the tensile strength of the open area 1111 is greater than or equal to 100 MPa.

[0186] The present application is further described below with reference to examples.

[0187] In order to make the invention purpose, technical scheme and beneficial technical effect of this application clearer, this application is further described in detail below with reference to the examples. However, it should be understood that the examples of this application are only for the purpose of explaining this application and are not intended to limit this application, and the examples of this application are not limited to the examples given in the specification. In the examples, where specific experimental conditions or operating conditions are not specified, they were prepared under conventional conditions or under conditions recommended by the material supplier.

[0188] Example 1:

[0189] (i) A long steel foil having a length L of 3000 m, a width W0 of 320 mm, and a thickness T of 10 μm is provided.

[0190] (ii) A circular array of through holes was formed on the steel foil, with a diameter D of 20 μm. The through holes were arranged in an array. Specifically, 1,750 rows of through holes were formed on the steel foil, evenly spaced across the width of the foil. The spacing D1 between adjacent through holes in the width direction was 100 μm. Each row of through holes was evenly spaced across the length of the foil, with the spacing D2 between adjacent through holes in the length direction being 100 μm. Each row of through holes extended to both ends of the foil in the length direction.

[0191] After the through holes are formed in the steel foil, a current collector is formed. The current collector includes an edge region 1114, an open hole region 1111, and a second non-porous region 1113 arranged along the width direction. As shown in Figure 11, the width K0 of the edge region 114 is 60 mm, the width W of the open hole region is 210 mm, and the width K2 of the second non-porous region is 50 mm.

[0192] (iii) Following steps (i) and (ii) above, 10 current collectors were prepared.

[0193] (iv) Cut a sample from the opening area of ​​one current collector. The sample measures 100 mm in the length direction and 20 mm in the width direction. Mount the sample on a tensile testing machine and start the machine. Stretching the sample at 50 mm / min, record the force at break as F (in Newtons). Calculate the tensile strength of the sample along the length of the current collector as P = F / (20 mm × 0.01 mm).

[0194] (v) Ten current collectors were sequentially subjected to coating, rolling, and cutting processes to produce multiple electrode sheets. As shown in Figure 12, the length L1 of the electrode sheet is 3400 mm, and the width W1 of the active material layer (in Figure 12, the active material layer is represented by diagonal lines) is 310 mm. After cutting, the edge area forms a first non-porous region and a tab. The width K1 of the first non-porous region is 50 mm, and the width W2 of the tab is 10 mm.

[0195] During the preparation of the electrode sheet, the number of times the current collector breaks is recorded, and the current collector breakage rate M is calculated. The unit of the breakage rate M is times / 1000m, that is, the number of times the current collector breaks for every 1000m of tape travel.

[0196] (vi) The prepared electrode pieces are wound, shelled, and injected with liquid to prepare 20 battery cells. After injection, the 20 battery cells are left to rest. Then, one battery cell is disassembled every 20 minutes, and the wetting status of the disassembled electrode pieces is observed (the color of the electrode piece can be used to determine whether the area is wet). This is done until a completely wetted electrode piece is removed. The length of time the corresponding battery cell is left to rest is recorded, which can represent the length of time the electrode piece is completely wetted.

[0197] Example 2-8: The test method of Example 2-8 refers to Example 1. The differences between Example 2-8 and Example 1 are shown in Table 1.

[0198] Comparative Examples 1-3: The test methods of Comparative Examples 1-3 refer to Example 1. The differences between Comparative Examples 1-3 and Example 1 are shown in Table 1.

[0199] It is supplemented here that in Comparative Example 3, the diameter of the through hole is 0, that is, no through hole is provided on the current collector of Comparative Example 3. The time length for the electrode of Comparative Example 3 to be completely wetted is Q.

[0200] Table 1

[0201]

[0202] Referring to Examples 1-8 and Comparative Example 3, through-holes are provided in the current collector to form channels for electrolyte flow, thereby improving the electrode sheet's wetting efficiency and consistency, and enhancing the cycling performance of the battery cell. Referring to Examples 1-8 and Comparative Examples 1-2, limiting the tensile strength of the open area in the longitudinal direction to greater than or equal to 100 MPa can reduce the risk of current collector fracture.

[0203] The inventors also conducted the above experiments on aluminum current collectors, copper current collectors, nickel current collectors, etc., and found that when the tensile strength is limited to greater than or equal to 100 MPa, the risk of current collector breakage can also be reduced.

[0204] Example 9:

[0205] (i) A long steel foil having a length L of 3000 m, a width W0 of 320 mm, and a thickness T of 10 μm is provided.

[0206] (ii) A circular through-hole array was formed on the steel foil, with a diameter D of 50 μm. The through-holes were arranged in an array. Specifically, 1,500 rows of through-holes were formed on the steel foil, evenly spaced across the width of the foil. The spacing D1 between adjacent through-holes in the width direction was 90 μm. Each row of through-holes was evenly spaced across the length of the foil, with the spacing D2 between adjacent through-holes in the length direction being 90 μm. Each row of through-holes extended to both ends of the foil in the length direction.

[0207] After the through-holes are formed in the steel foil, the current collector is formed. The current collector comprises an edge region, an open-hole region, and a second, non-porous region arranged along the width. As shown in Figure 11, the width of the edge region, K0, is 60 mm, the width of the open-hole region, W, is 210 mm, and the width of the second, non-porous region, K2, is 50 mm.

[0208] Calculate the porosity G of the open area. For example, the porosity G is calculated based on an open area of ​​210 mm × 210 mm. In this open area, the number of through holes is 1500 × 1500. The area of ​​a single through hole is π × 0.025 2 mm 2 ; Porosity of the open area G = 1500 × 1500 × π × 0.025 2 / (210×210).

[0209] (iii) Following steps (i) and (ii) above, 10 current collectors were prepared.

[0210] (iv) Ten current collectors were sequentially subjected to coating, rolling, and cutting processes to produce multiple electrode sheets. As shown in Figure 12, the length L1 of the electrode sheet is 3400 mm, and the width W1 of the active material layer is 310 mm. The edge area is cut to form a first non-porous region and a tab. The width K1 of the first non-porous region is 50 mm, and the width W2 of the tab is 10 mm.

[0211] During the preparation of the electrode sheet, the number of times the current collector breaks is recorded, and the current collector breakage rate M is calculated. The unit of the breakage rate M is times / 1000m, that is, the number of times the current collector breaks for every 1000m of tape travel.

[0212] (v) The prepared electrode pieces are subjected to winding, casing, and liquid injection processes to prepare 20 battery cells. After liquid injection, the 20 battery cells are left to rest. Then, one battery cell is disassembled every 20 minutes, and the wetting status of the disassembled electrode pieces is observed (the color of the electrode piece can be used to determine whether the area is wet). This is done until a completely wet electrode piece is removed. The length of time the corresponding battery cell remains stationary is recorded, which indicates how long the electrode piece has been completely wetted.

[0213] Examples 10-14: The test methods of Examples 10-14 refer to those of Example 9. The differences between Examples 10-14 and Example 9 are shown in Table 2.

[0214] Comparative Examples 4-7: The testing method for Comparative Examples 4-7 refers to that of Example 9. The differences between Comparative Examples 4-7 and Example 9 are shown in Table 2. It should be noted that in Comparative Example 7, the diameter of the through-hole is 0, meaning that no through-hole is provided on the current collector. The time required for the electrode to be fully wetted in Comparative Example 7 is Q.

[0215] Table 2

[0216]

[0217] Referring to Examples 9-14 and Comparative Examples 5-7, by providing through-holes in the current collector to form channels for electrolyte flow, the electrode sheet wetting efficiency and consistency are improved, thereby enhancing the cycling performance of the battery cell. Referring to Examples 9-14 and Comparative Examples 4-6, limiting the S1 / S2 value to 0.1-0.7 can improve electrode sheet wetting efficiency and reduce the risk of current collector fracture.

[0218] Example 15:

[0219] (i) A long steel foil having a length L of 3000 m, a width W0 of 320 mm, and a thickness T of 10 μm is provided.

[0220] (ii) A circular array of through holes was formed on the steel foil, with a diameter D of 50 μm. The through holes were arranged in an array. Specifically, 1,400 rows of through holes were formed on the steel foil, evenly spaced across the width of the foil. The spacing D1 between adjacent through holes in the width direction was 100 μm. Each row of through holes was evenly spaced along the length direction, with the spacing D2 between adjacent through holes in the length direction being 100 μm. Each row of through holes extended to both ends of the foil in the length direction.

[0221] After the through-holes are formed in the steel foil, the current collector is formed. The current collector comprises an edge region, an open-hole region, and a second, non-porous region arranged along the width. As shown in Figure 11, the width of the edge region, K0, is 60 mm, the width of the open-hole region, W, is 210 mm, and the width of the second, non-porous region, K2, is 50 mm.

[0222] (iii) Following steps (i) and (ii) above, 10 current collectors were prepared.

[0223] (iv) Ten current collectors were sequentially subjected to coating, rolling, and cutting processes to produce multiple electrode sheets. As shown in Figure 12, the length L1 of the electrode sheet is 3400 mm, and the width W1 of the active material layer is 310 mm. The edge area is cut to form a first non-porous region and a tab. The width K1 of the first non-porous region is 50 mm, and the width W2 of the tab is 10 mm.

[0224] During the preparation of the electrode sheet, the number of times the current collector breaks is recorded, and the current collector breakage rate M is calculated. The unit of the breakage rate M is times / 1000m, that is, the number of times the current collector breaks for every 1000m of tape travel.

[0225] (v) The prepared electrode pieces are subjected to winding, casing, and liquid injection processes to prepare 20 battery cells. After liquid injection, the 20 battery cells are left to rest. Then, one battery cell is disassembled every 20 minutes, and the wetting status of the disassembled electrode pieces is observed (the color of the electrode piece can be used to determine whether the area is wet). This is done until a completely wet electrode piece is removed. The length of time the corresponding battery cell remains stationary is recorded, which indicates how long the electrode piece has been completely wetted.

[0226] Examples 16-19: The test methods of Examples 16-19 refer to Example 15. The differences between Examples 16-19 and Example 15 are shown in Table 3.

[0227] Comparative Examples 8-11: The test method of Comparative Examples 8-11 refers to Example 15. The differences between Comparative Examples 8-11 and Example 15 are shown in Table 3.

[0228] It is supplemented here that in Comparative Example 9, the diameter of the through hole is 0, that is, no through hole is provided on the current collector of Comparative Example 9. The time length for the electrode of Comparative Example 9 to be completely soaked is Q.

[0229] In Examples 15-19 and Comparative Examples 8-11, the aperture D, spacing D1 and D2 of the through holes remain unchanged; when W changes, the number of rows of through holes is changed.

[0230] Table 3

[0231]

[0232] With reference to Examples 15-19 and Comparative Examples 8-9, through-holes are provided in the current collector to form channels for electrolyte flow, thereby improving the electrode sheet wetting efficiency and consistency, thereby enhancing the cycling performance of the battery cell. With reference to Examples 15-19 and Comparative Examples 8-11, K1 / (W+K1+K2) is limited to 3%-32%, and K2 / (W+K1+K2) is limited to 3%-32%, thereby improving the electrode sheet wetting efficiency and reducing the risk of current collector fracture.

[0233] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0234] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A current collector for a pole piece, comprising an open area with a plurality of through holes.

2. The current collector according to claim 1, wherein In at least one direction perpendicular to the thickness direction of the current collector, the tensile strength of the open area is greater than or equal to 100 MPa.

3. The current collector according to claim 1 or 2, wherein: The current collector further includes a first non-porous region, the first non-porous region being located on one side of the open-porous region along the first direction; the first non-porous region is not provided with the through-hole; The first direction is perpendicular to a thickness direction of the current collector. 4 . The current collector according to claim 3 , further comprising a tab protruding from an edge of the first non-porous region away from the open-porous region.

5. The current collector according to claim 3 or 4, wherein: In the second direction, the tensile strength of the open area is greater than or equal to 100 MPa; The first direction, the second direction, and the thickness direction are perpendicular to each other. The current collector according to claim 5 , wherein: In the second direction, the tensile strength of the first non-porous region is greater than or equal to 500 MPa.

7. The current collector according to any one of claims 3 to 6, wherein: In the first direction, the tensile strength of the open area is greater than or equal to 100 MPa.

8. The current collector according to any one of claims 3 to 7, wherein: The current collector further includes a second non-porous region, which is located on a side of the open-porous region away from the first non-porous region, and the second non-porous region is not provided with the through-holes.

9. The pole piece according to claim 8, wherein: In the first direction, the size of the open area is W, the size of the first non-porous area is K1, and the size of the second non-porous area is K2; W, K1, and K2 satisfy: 3%≤K1 / (W+K1+K2)≤32%, 3%≤K2 / (W+K1+K2)≤32%.

10. The pole piece according to claim 8 or 9, wherein: In the first direction, the size of the first non-porous area is 10 mm-100 mm.

11. The current collector according to any one of claims 1 to 10, wherein: The total area of ​​the plurality of through holes is S1, the total area of ​​the opening region is S2, and S1 and S2 satisfy: 0.1≤S1 / S2≤0.

7.

12. The current collector according to claim 11, wherein S1 and S2 satisfy: 0.3≤S1 / S2≤0.

7.

13. The current collector according to any one of claims 1 to 12, wherein: The through hole has a diameter of 0.02 mm to 2 mm.

14. The current collector according to claim 13, wherein: The through hole has a diameter of 0.2 mm to 0.5 mm.

15. The current collector according to any one of claims 1 to 14, wherein The material of the current collector is selected from at least one of aluminum, copper, nickel and steel.

16. The current collector according to claim 15, wherein: The material of the current collector is stainless steel.

17. The current collector according to any one of claims 1 to 16, wherein: The plurality of through holes are arranged in an array along a first direction and a second direction; The first direction, the second direction, and the thickness direction of the current collector are perpendicular to each other.

18. A pole piece, comprising: The current collector according to any one of claims 1 to 17; as well as An active material layer is coated on the surface of the current collector and covers the open area.

19. A pole piece, comprising: The current collector according to any one of claims 8 to 10; as well as An active material layer is coated on the open-pore area, the first non-porous area and the second non-porous area.

20. An electrode assembly comprising the electrode piece according to claim 18 or 19.

21. A battery cell comprising: shell; as well as The electrode assembly according to claim 20, housed in the housing.

22. A battery comprising a plurality of battery cells according to claim 21.

23. An electrical device comprising the battery cell according to claim 21, wherein the battery cell is used to provide electrical energy.

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