WO2024055187A1 - Current collector, electrode plate, electrode assembly, battery cell, battery and electric device - Google Patents

Abstract

Provided in the embodiments of the present application are a current collector, an electrode plate, an electrode assembly, a battery cell, a battery and an electric device. The electrode plate comprises the current collector and an active substance layer, which is applied to a surface of the current collector; the current collector comprises a holed area provided with a plurality of through holes, and the active substance layer covers the holed area; and the current collector is provided with the through holes to form a channel for allowing an electrolyte to pass through, such that the infiltration efficiency of the electrode plate is improved, and the infiltration consistency of the electrode plate is improved, thereby improving the cycle performance of the battery cell.

Description

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

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 technique

Battery cells are widely used in electronic devices, such as mobile phones, laptops, battery cars, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, electric tools, etc.

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

Contents of the invention

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

In a first aspect, embodiments of the present application provide a current collector for a pole piece, which includes an opening area with a plurality of through holes.

Through holes are opened on the current collector to form a channel for the electrolyte to pass through, thereby improving the infiltration efficiency of the pole pieces, improving the consistency of the infiltration of the pole pieces, and improving the cycle performance of the battery cells.

In some embodiments, 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. The above technical solution can reduce the risk of breakage of the current collector.

In some embodiments, the current collector further includes a first non-porous area located on one side of the opening area along the first direction; the first non-porous area is not provided with through holes. The first direction is perpendicular to the thickness direction of the current collector. By providing the first non-porous area, the distance between the opening area and the edge of the current collector along the first direction can be increased, thereby reducing the risk of breakage in the opening area.

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

The first non-porous area separates the pole tab from the opening area, so as to reduce the risk of cutting into the opening area during the cutting and forming process of the pole tab, thereby reducing the risk of breakage in the opening area.

In some embodiments, 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 above technical solution can reduce the risk of breakage of the current collector when the current collector is pulled in the second direction.

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

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 breakage of the current collector when the current collector is pulled along the first direction.

In some embodiments, the current collector further includes a second non-porous area, the second non-porous area is located on a side of the open area away from the first non-porous area, and the second non-porous area is not provided with through holes. By providing the second non-porous area, the distance between the opening area and the edge of the current collector along the first direction can be increased, thereby reducing the risk of breakage in the opening area.

In some embodiments, in the first direction, the size of the open area is W, the size of the first non-pore area is K ₁ , and the size of the second non-pore area is K ₂ . W, K ₁ and K ₂ satisfy: 3%≤K ₁ /(W+K ₁ +K ₂ )≤32%, 3%≤K ₂ /(W+K ₁ +K ₂ )≤32%. The above technical solution can improve the wetting efficiency of the pole piece and reduce the risk of breakage of the current collector.

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

In some embodiments, the total area of the multiple through holes is S ₁ and the total area of the opening area is S ₂ , and S ₁ and S ₂ satisfy: 0.1 ≤ S ₁ /S ₂ ≤ 0.7. Limiting the value of S ₁ /S ₂ to 0.1-0.7 can improve the wetting efficiency of the pole piece and reduce the risk of current collector breakage.

In some embodiments, S ₁ and S ₂ satisfy: 0.3≤S ₁ /S ₂ ≤0.7. When 0.3≤S ₁ /S ₂ ≤0.7, the wetting efficiency of the pole piece can be better improved and the risk of current collector breakage can be further reduced.

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

In some embodiments, the through hole has a diameter of 0.2mm-0.5mm. Limiting D to 0.2mm-0.5mm can reduce the risk of current collector breakage and further simplify the current collector molding process.

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.

In some embodiments, the current collector is made of stainless steel. The current collector made of stainless steel has high tensile strength and can open more through holes to improve the wettability of the pole piece.

In some embodiments, the plurality of through holes are arranged in an array along the first direction and the second direction. The first direction, the second direction and the thickness direction of the current collector are two perpendicular to each other. The uniform distribution of multiple through holes can improve the consistency of pole piece infiltration, reduce the difference in tensile strength in the opening area, and reduce the risk of current collector breakage.

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

The electrolyte can pass through the opening area and infiltrate the active material layers on both sides of the opening area, thereby improving the infiltration efficiency, reducing the wettability difference of the active material layers on both sides of the opening area, and improving the infiltration consistency of the pole piece. Improve the cycle performance of battery cells.

In some embodiments, the active material layer is coated on the open pore area, the first non-porous area and the second non-porous area.

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

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 cutting process of the tab and reduce the risk of defects on the cutting edge extending to the opening area. , thereby reducing the risk of current collector fracture and improving the flow capacity of the current collector.

In a third aspect, embodiments of the present application provide an electrode assembly, including the pole piece provided in any embodiment of the second aspect.

In a fourth aspect, embodiments of the present application provide a battery cell, including a casing and an electrode assembly provided in any embodiment of the third aspect, and the electrode assembly is accommodated in the casing.

In a fifth aspect, embodiments of the present application provide a battery, including a plurality of battery cells provided in any embodiment of the fourth aspect.

In a sixth aspect, embodiments of the present application provide an electrical device, including the battery cell provided in any embodiment of the fourth aspect, and the battery cell is used to provide electric energy.

Description of drawings

In order to explain the technical solutions of the embodiments of the present application more clearly, the drawings required to be used 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. Those of ordinary skill in the art can also obtain other drawings based on the drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application;

Figure 2 is an exploded schematic diagram of a battery provided by some embodiments of the present application;

Figure 3 is a schematic structural diagram of the battery module shown in Figure 2;

Figure 4 is an exploded schematic diagram of a battery cell provided by some embodiments of the present application;

Figure 5 is a schematic structural diagram of an electrode assembly of a battery cell provided by some embodiments of the present application;

Figure 6 is a schematic structural diagram of a pole piece provided by some embodiments of the present application;

Figure 7 is a schematic cross-sectional view of the pole piece shown in Figure 6 along line A-A;

Figure 8 is a schematic structural diagram of a current collector according to some embodiments of the present application;

Figure 9 is an enlarged schematic diagram of Figure 8 at circular frame A;

Figure 10 is a schematic structural diagram of a current collector according to other embodiments of the present application;

Figure 11 is a schematic structural diagram of a current collector provided by some embodiments of the present application;

Figure 12 is a schematic structural diagram of a pole piece provided by some embodiments of the present application.

In the drawings, the drawings are not drawn to actual scale.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are Apply for some of the embodiments, not all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the technical field of this application; the terms used in the specification of this application are only for describing specific implementations. The purpose of the examples is not intended to limit the application; the terms "including" and "having" and any variations thereof in the description and claims of the application and the above description of the drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or priority relationship.

Reference in this application to "an embodiment" means 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 appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

In the description of this application, it should be noted that, unless otherwise clearly stated and limited, the terms "installation", "connection", "connection" and "attachment" should be understood in a broad sense. For example, it can be a fixed connection, It can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediate medium; it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

The term "and/or" in this application is just an association relationship describing related objects, indicating that there can be three relationships, for example, A and/or B, which can mean: A exists alone, A and B exist simultaneously, alone There are three situations B. In addition, the character "/" in this application generally indicates that the related objects are an "or" relationship.

In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of simplicity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length and width of the integrated device, are only illustrative illustrations and should not constitute any limitation to the present application. .

"Plural" appearing in this application means two or more (including two).

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

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, etc., The embodiments of the present application are not limited to this. The battery cell may be in the shape of a cylinder, a flat body, a rectangular parallelepiped or other shapes, and the embodiments of the present application are not limited to this.

The battery mentioned in the embodiments of this application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. The battery may also generally include a case for enclosing one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

The battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode piece, a negative electrode piece and a separator. Battery cells mainly rely on the movement of metal ions between the positive and negative electrodes 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 cathode current collector can be aluminum, and the cathode active material layer includes cathode active materials. The cathode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganate, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector. The negative electrode current collector may be made of copper, and the negative electrode active material layer may include a negative electrode active material. The negative electrode active material may be carbon or silicon. The material of the isolator can be PP (polypropylene, polypropylene) or PE (polyethylene, polyethylene), etc.

In the battery cell, the electrolyte is the ion conductor that plays a conductive role between the positive and negative electrode sheets. During the charging and discharging process, lithium ions are transported back and forth between the positive and negative electrode sheets. The electrolyte has a relatively large impact on the charge and discharge performance, cycle life, and temperature range of the battery cells.

Battery cells with poor cycle performance are often related to the poor wetting effect of the electrolyte on the electrode plates. When the electrolyte infiltration effect is not good, the ion transmission path becomes longer, hindering the shuttle of ions between the positive and negative electrode plates. The electrode plates that are not in contact with the electrolyte cannot participate in the electrochemical reaction. At the same time, the cross-sectional resistance of the battery increases, affecting the battery cell performance. rate performance, discharge capacity and service life of the body.

The current collector (such as the positive electrode current collector or the negative electrode current collector) is an indispensable part of the pole piece. It not only plays the role of carrying active materials, but also collects the electrons generated by the electrochemical reaction and guides them to the external circuit, thereby realizing chemical The process of converting energy into electrical energy. However, the inventor noticed that it is difficult for the electrolyte to pass through the current collector. In other words, the current collector will block the flow of the electrolyte, reduce the efficiency of electrolyte infiltration, cause a difference in wettability of the active material layers on both sides of the current collector, and affect the battery. Cycling performance of the monomer.

In view of this, embodiments of the present application propose a technical solution that opens through holes on the current collector to form a channel for the electrolyte to pass through, thereby improving the infiltration efficiency of the pole piece and improving the consistency of the infiltration of the pole piece. , improve the cycle performance of battery cells.

The pole pieces described in the embodiments of this application are suitable for battery cells, batteries, and electrical devices using batteries.

Electrical devices can be vehicles, cell phones, portable devices, laptops, ships, spacecraft, electric toys and power tools, etc. Vehicles can be fuel vehicles, gas vehicles or new energy vehicles, and new energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles, etc.; spacecraft include aircraft, rockets, space shuttles, spaceships, etc.; electric toys include fixed Type 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, for example, Electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, planers and more. The embodiments of this application impose no special restrictions on the above-mentioned electrical devices.

For convenience of explanation, the following embodiments take the electric device as a vehicle as an example.

Figure 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.

As shown in FIG. 1 , a battery 2 is provided inside the vehicle 1 , and the battery 2 can 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 be used as an operating power source for the vehicle 1 .

The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery 2 to provide power to the motor 4, for example, to meet the power requirements for starting, navigation and driving of the vehicle 1.

In some embodiments of the present application, the battery 2 can not only be used as the operating power source of the vehicle 1, but also can be used 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.

Figure 2 is an exploded schematic diagram of a battery provided by some embodiments of the present application.

As shown in FIG. 2 , the battery 2 includes a case 5 and a battery cell (not shown in FIG. 2 ), and the battery cell is accommodated in the case 5 .

The box 5 is used to accommodate battery cells, and the box 5 can be of various structures. In some embodiments, the box body 5 may include a first box body part 5a and a second box body part 5b. The first box body part 5a and the second box body part 5b cover each other. The first box body part 5a and the second box body part 5b cover each other. The two box portions 5b jointly define an accommodating space 5c for accommodating battery cells. The second box part 5b can be a hollow structure with one end open, and the first box part 5a is a plate-like structure. The first box part 5a is covered with the opening side of the second box part 5b to form a receiving space 5c. The box body 5; the first box body part 5a and the second box body part 5b can also be a hollow structure with one side open, and the opening side of the first box body part 5a is covered with the opening side of the second box body part 5b , to form a box 5 having an accommodation space 5c. Of course, the first box part 5a and the second box part 5b can be in various shapes, such as cylinder, rectangular parallelepiped, etc.

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

Assuming that the first box part 5a is covered with the top of the second box part 5b, the first box part 5a can also be called an upper box cover, and the second box part 5b can also be called a lower box.

In the battery 2, there may be one battery cell or a plurality of battery cells. If there are multiple battery cells, the multiple battery cells can be connected in series, in parallel, or in mixed connection. Mixed connection means that multiple battery cells are connected in series and in parallel. Multiple battery cells can be directly connected in series or parallel or mixed together, and then the whole composed of multiple battery cells can be accommodated in the box 5; of course, multiple battery cells can also be connected in series or parallel first or A battery module 6 is formed by a mixed connection, and multiple battery modules 6 are connected in series, parallel, or mixed to form a whole, and are accommodated in the box 5 .

FIG. 3 is a schematic structural diagram of the battery module shown in FIG. 2 .

As shown in FIG. 3 , in some embodiments, there are multiple battery cells 7 , and the plurality of battery cells 7 are first connected in series, parallel, or mixed to form the battery module 6 . A plurality of battery modules 6 are connected in series, parallel, or mixed to form a whole, and are accommodated in the box.

The plurality of battery cells 7 in the battery module 6 can be electrically connected through bus components to achieve parallel, series or mixed connection of the plurality of battery cells 7 in the battery module 6 .

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

FIG. 4 is an exploded schematic diagram of a battery cell provided by some embodiments of the present application; FIG. 5 is a schematic structural diagram of an electrode assembly of a battery cell provided by some embodiments of the present application.

As shown in FIGS. 4 and 5 , battery cells in some embodiments of the present application include a casing 20 and an electrode assembly 10 , and the electrode assembly 10 is accommodated in the casing 20 .

The casing 20 has a hollow structure, and an accommodation cavity for accommodating the electrode assembly 10 and the electrolyte is formed inside. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10 . For example, if the electrode assembly 10 has a cylindrical structure, a cylindrical shell can be selected; if the electrode assembly 10 has a rectangular parallelepiped structure, a rectangular parallelepiped shell can be selected. Optionally, both the electrode assembly 10 and the housing 20 are cylindrical.

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

The end cap 22 is sealingly connected 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 the end cap 22 is provided as one and covers the opening of the housing 21 . In other examples, the two opposite ends of the housing 21 have openings, and two end caps 22 are provided, and the two end caps 22 cover the two openings of the housing 21 respectively.

In some embodiments, electrode assembly 10 includes a plurality of pole pieces and spacers 12 . Exemplarily, the pole pieces are provided in multiple numbers, and the plurality of pole pieces include a first pole piece 11a and a second pole piece 11b with opposite polarities, and the separator 12 is used to insulate the first pole piece 11a and the second pole piece 11b. isolation. The electrode assembly 10 mainly relies on the movement of metal ions between the first pole piece 11a and the second pole piece 11b to work.

One of the first pole piece 11a and the second pole piece 11b is a positive pole piece, and the other one of the first pole piece 11a and the second pole piece 11b is a negative pole piece.

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 around the central axis to be integrated. Form a coiled structure. The winding structure can be a cylindrical structure, a flat structure or other shaped structures.

In some embodiments, the battery cell 7 further includes an electrode terminal 30 , which is disposed on the housing 20 and used to electrically connect with the electrode assembly 10 to export the electric energy generated by the electrode assembly 10 . Illustratively, at least part of the electrode terminal 30 is exposed to the outside of the housing 20 to achieve electrical connection with other structures (eg, bus components).

Figure 6 is a schematic structural diagram of the pole piece provided by some embodiments of the present application; Figure 7 is a schematic cross-sectional view of the pole piece shown in Figure 6 along line A-A.

As shown in FIGS. 6 and 7 , embodiments of the present application provide a pole piece 11 , which includes a current collector 111 and an active material layer 112 coated on the surface of the current collector 111 .

The pole piece 11 in this embodiment can be a positive pole piece in the electrode assembly, or it can be a negative pole piece in the electrode assembly.

The active material layer 112 may be coated on one surface of the current collector 111 , or may be coated on both surfaces of the current collector 111 . The active material layer 112 can be used to perform electrochemistry with the electrolyte to generate electric current. The current collector 111 can collect the generated current together and guide the current to an external circuit.

As shown in FIG. 6 , the active material layer 112 may be partially located in the through hole 113 . It can be understood that there may be no active material layer 112 in the through hole 113 .

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

Figure 8 is a schematic structural diagram of a current collector according to some embodiments of the present application; Figure 9 is an enlarged schematic diagram of Figure 8 at circular frame A.

Please refer to FIGS. 6 to 9 together. The embodiment of the present application provides a current collector 111 for the pole piece 11 . The current collector 111 includes an opening area 1111 with a plurality of through holes 113 .

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

The through hole 113 may be a round hole, a square hole, a triangular hole, a waist hole or other shaped holes.

The current collector 111 has electrical conductivity. The embodiment of the present application 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 of metal and plastic.

On the current collector 111, the plurality of through holes 113 can be evenly distributed according to a certain set rule; for example, the plurality of through holes 113 can be distributed in a rectangular array or a circular array. In some examples, multiple through holes 113 are arranged in multiple rows, and the through holes 113 in two adjacent rows can be aligned or offset. Alternatively, the plurality of through holes 113 may also be irregularly distributed on the current collector 111 .

The opening area 1111 can be determined by the boundary of the outermost through hole 113 . For example, when the distribution range of the multiple through holes 113 is rectangular, the opening area 1111 can be the smallest rectangle that can contain all the through holes 113; when the distribution range of the multiple through holes 113 is circular, the opening area 1111 1111 may be the smallest circle capable of containing all through holes 113 . When the distribution range of the plurality of through holes 113 is irregular, the common tangent line of the outermost through hole 113 is used as the boundary of the opening area 1111.

In the embodiment of the present application, a through hole 113 is opened in the current collector 111 to form a channel for the electrolyte to pass through, thereby improving the infiltration efficiency of the pole piece 11, improving the consistency of the infiltration of the pole piece 11, and improving the efficiency of the battery cells. cycle performance.

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

Tensile strength can also be called tensile strength. Tensile strength is the resistance to the maximum uniform plastic deformation of a material. Before the tensile specimen is subjected to the maximum tensile stress, the deformation is uniform, but after it exceeds the maximum tensile stress, the material begins to shrink, that is, concentrated deformation occurs; for no (or Very small) brittle material with uniform plastic deformation, which reflects the material's fracture resistance. For metal materials, tensile strength is the critical value at which the metal transitions from uniform plastic deformation to localized concentrated plastic deformation. It is also the maximum load-bearing capacity of the metal under static tension.

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

During the production process of the pole piece 11, the pole piece 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 coated on 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 cutting During the process, the current collector 111 can be cut to form the tabs 1112a of the pole piece 11.

In multiple processes, the current collector 111 will be stretched. In order to reduce the risk of breakage of the current collector 111, the tensile strength of the current collector 111 needs to meet the requirements. The inventor noticed that providing the through hole 113 on the current collector 111 will reduce the tensile strength of the opening area 1111; if the tensile strength of the opening area 1111 is insufficient, it will increase the risk of breakage of the current collector 111 and affect the product. Excellent rate.

After in-depth research and extensive experiments, the inventor found that the tensile strength of the opening area 1111 in the direction of greater tensile force is greater than or equal to 100MPa, which can reduce the risk of breakage of the current collector 111.

For example, the tensile strength of the opening area 1111 can be measured as follows: Ⅰ) Cut a rectangular sample on the opening area 1111. The length, width and thickness of the sample are U ₁ and U ₂ respectively. and U ₃ ; Ⅱ) Place the sample on the tensile machine, and fix both ends of the sample along the length direction on the clamps of the tensile machine; Ⅲ) Turn on the tensile machine, and the tensile machine stretches at a set speed (for example, 50mm/min) Sample, record the corresponding force when the sample breaks as F (unit N); IV) The tensile strength of the sample along the length direction P=F/(U ₂ × U ₃ ).

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

The edges of the current collector 111 are prone to defects, and when the current collector 111 is stretched, the defects may worsen and cause microcracks. If the distance between the opening area 1111 and the edge of the current collector 111 is too small, microcracks may extend to the through hole 113 , thereby causing the risk of the entire opening area 1111 breaking.

By arranging the first non-porous area 1112, the embodiment of the present application can increase the distance between the opening area 1111 and the edge of the current collector 111 along the first direction X, thereby reducing the risk of breakage of the opening area 1111.

In some embodiments, the current collector 111 further includes a tab 1112a protruding from an edge of the first non-porous region 1112 away from the porous region 1111.

The tab 1112a is used to electrically connect with the electrode terminal to draw out the current collected by the current collector 111.

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 shaping process of the tab 1112a. This reduces the risk of breakage of the opening area 1111 .

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

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

Compared with the first direction X, the current collector 111 is more susceptible to the tensile force in the second direction Y. For example, during the production process of the pole piece 11, it needs to be tightened under the action of pulling force, and the direction of the pulling force is generally consistent with the second direction Y, which causes the current collector 111 to receive a larger pulling force in the second direction Y. .

The tensile force received by the opening area 1111 in the first direction X is 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 region 1111 in the first direction X may be greater than, less than, or equal to 100 MPa.

In the embodiment of the present application, the tensile strength of the opening 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 .

For example, the first direction X and the second direction Y are two directions of the current collector 111 in a flat state. Optionally, the first direction X is the width direction of the current collector 111 in the flattened state, and the second direction Y is the length direction of the current collector 111 in the flattened state.

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.

The edges of the first non-porous area 1112 are prone 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 defects worsening; if the tensile strength of the first non-porous region 1112 is insufficient, there may be a risk of cracking of the first non-porous region 1112 ; If the first non-porous area 1112 cracks, the generated cracks may extend to the open hole area 1111, thereby causing the current collector 111 to break.

After in-depth research and extensive experiments, the inventor found that the tensile strength of the first non-porous region 1112 in the second direction Y is greater than or equal to 500MPa, which can reduce the risk of breakage of the current collector 111 and improve the performance of the current collector 111. flow capability.

In some embodiments, in the first direction X, the tensile strength of the opening region 1111 is greater than or equal to 100 MPa.

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.

In some embodiments, the current collector 111 further includes a second non-porous area 1113, which is located on a side of the opening area 1111 away from the first non-porous area 1112, and the second non-porous area 1113 is not provided with through holes. 113.

The edges of the current collector 111 are prone to defects, and when the current collector 111 is stretched, the defects may worsen and cause microcracks. If the distance between the opening area 1111 and the edge of the current collector 111 is too small, microcracks may extend to the through hole 113, thereby causing the risk of the entire opening area 1111 breaking.

By arranging the second non-porous area 1113, the embodiment of the present application can increase the distance between the opening area 1111 and the edge of the current collector 111 along the first direction X, thereby reducing the risk of breakage of the opening area 1111.

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.

In some embodiments, the total area of the plurality of through holes 113 is S ₁ , the total area of the opening area 1111 is S ₂ , and S ₁ and S ₂ satisfy: 0.1 ≤ S ₁ /S ₂ ≤ 0.7.

The greater the value of S ₁ /S ₂ , the easier it is for the electrolyte to pass through the opening area 1111 , the more obvious the improvement of the infiltration efficiency of the pole piece 11 by the through hole 113 , and the better the consistency of the infiltration of the pole piece 11 . However, the larger the value of S ₁ /S ₂ is, the lower the tensile strength of the opening region 1111 is, and the easier it is for the current collector 111 to break during the molding process.

The smaller the value of S ₁ /S ₂ is, the higher the tensile strength of the opening area 1111 is, and the lower the risk of breakage of the current collector 111 during the molding process. However, the smaller the value of S ₁ /S ₂ is, the more difficult it is for the electrolyte to pass through the opening area 1111 , and the smaller the improvement in the wetting efficiency of the pole piece 11 by the through hole 113 is.

After in-depth research and extensive experiments, the inventor found that limiting the value of S ₁ /S ₂ to 0.1-0.7 can improve the wetting efficiency of the pole piece 11 and reduce the risk of breakage of the current collector 111 .

Optionally, the value of S ₁ /S ₂ is 0.1, 0.3, 0.5, 0.6 or 0.7.

In some embodiments, S ₁ and S ₂ satisfy: 0.3≤S ₁ /S ₂ ≤0.7.

After in-depth research and extensive experiments, the inventor found that when 0.3≤S ₁ /S ₂ ≤0.7, the wetting efficiency of the pole piece 11 can be better improved and the risk of breakage of the current collector 111 can be further reduced.

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

The through hole 113 may be a round hole, a square hole, or a hole in 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 .

Under the premise that the total area of the through holes 113 in the opening area 1111 is constant, the smaller the diameter D of the through hole 113, the greater the number of through holes 113 that need to be opened, and the more complicated the process of opening holes in the current collector 111. The fluid 111 is formed less efficiently. Under the premise that the total area of the through holes 113 in the opening area 1111 is constant, the larger the diameter D of the through hole 113, the easier it is for stress concentration to occur around the through hole 113, and the easier it is for the opening area to deform and break when subjected to tension.

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 appear. Leakage, resulting in waste of active substances.

After in-depth research and extensive experiments, the inventor found that the diameter D of the through hole 113 is limited to 0.02mm-2mm to reduce the risk of breakage of the current collector 111 and simplify the molding process of the current collector 111 .

Alternatively, the hole diameter D of the through hole 113 is limited to 0.02mm, 0.05mm, 0.1mm, 0.2mm, 0.5mm, 1mm, 1.5mm or 2mm.

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

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

For example, the current collector 111 may be aluminum foil, copper foil, nickel foil or steel foil. Alternatively, the current collector 111 may be laminated with at least two of aluminum foil, copper foil, nickel foil, and steel foil.

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

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 more through holes 113 can be opened to improve the wettability of the pole piece 11 .

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

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 of each row of through holes 113 are equidistantly arranged along the second direction Y.

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

Evenly distributing the plurality of through holes 113 can also reduce the difficulty of molding.

In some embodiments, aperture area 1111 is generally rectangular. Exemplarily, the opening area 1111 includes a first boundary 1111a and a second boundary 1111b that are oppositely arranged along the first direction X. The first boundary 1111a extends along the second direction Y and is connected to the first non-pore area 1112. The second boundary 1111b extends along the second direction Y and is connected to the second non-porous area 1113.

The first boundary 1111a is tangent to a row of through holes 113 close to the first non-hole area 1112, and the second boundary 1111b is tangent to a row of through holes 113 close to the second non-hole area 1113.

The embodiment of the present application also provides a pole piece 11, which includes the current collector 111 and the active material layer 112 of any of the previous embodiments. The active material layer 112 is coated on the surface of the current collector 111 and covers the opening area 1111.

The electrolyte can pass through the opening area 1111 and infiltrate the active material layers 112 on both sides of the opening area 1111, thereby improving the infiltration efficiency, reducing the wettability difference of the active material layers 112 on both sides of the opening area 1111, and improving the pole piece 11 The consistency of wetting improves the cycle performance of battery cells.

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

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

It is difficult for the electrolyte to infiltrate and coat the active material layer 112 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 that the electrolyte infiltrates and coats the active material layer 112 in the middle of the current collector 111. The infiltration efficiency of the active material layer 112 in the middle of the current collector 111 improves the consistency of the infiltration of the pole piece 11 and improves the cycle performance of the battery cell.

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

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

There may be one pole 1112a or multiple poles 1112a. For example, there are multiple tabs 1112a, and the plurality of tabs 1112a are spaced apart along the second direction Y.

The embodiment of the present application retains the first non-porous area 1112 between the tab 1112a and the opening area 1111 to separate the cutting edge from the opening area 1111 during the cutting process of the tab 1112a and reduce the cutting edge. The risk of defects extending to the opening area 1111 is thereby reduced, thereby reducing the risk of breakage of the current collector 111 and improving the flow capacity of the current collector 111 .

In some embodiments _{, in} the first direction W, K ₁ and K ₂ satisfy: 3%≤K ₁ /(W+K ₁ +K ₂ )≤32%, 3%≤K ₂ /(W+K ₁ +K ₂ )≤32%.

For example, a sample with size E along the second direction Y is cut from the current collector 111 , and two 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 opening region 1111 to E, K ₁ may be the ratio of the total area of the first non-porous region 1112 to E, and K ₂ may be the ratio of the total area of the first non-porous region 1112 to E. . Alternatively, when cutting the sample, the value of E can be greater than W+K ₁ +K ₂ .

The edges of the first non-porous area 1112 away from the hole-opening area 1111 and the edges of the second non-porous area 1113 away from the hole-opening area 1111 are prone to defects. When the current collector 111 is stretched, the defects may worsen and produce microcracks.

The smaller K ₁ /(W+K ₁ +K ₂ ) is, the smaller the distance between the edge of the first non-porous area 1112 and the opening area 1111 is. When the current collector 111 is pulled, the microstructure on the first non-porous area 1112 will be smaller. The higher the risk of cracks extending into through holes 113, the higher the risk of breakage of current collector 111. The greater K ₁ /(W+K ₁ +K ₂ ), the smaller the area of the opening area 1111, the higher the difficulty for the electrolyte to pass through the opening area 1111, and the more the through hole 113 improves the infiltration efficiency of the pole piece 11. Small.

Similarly, the smaller K ₂ /(W + K ₁ +K ₂ ), the smaller the distance between the edge of the second non-porous area 1113 and the opening area 1111. When the current collector 111 is pulled, the second non-porous area 1113 The higher the risk of microcracks extending to the through hole 113, the higher the risk of the current collector 111 breaking. The greater K ₂ /(W+K ₁ +K ₂ ), the smaller the area of the opening area 1111, the higher the difficulty for the electrolyte to pass through the opening area 1111, and the more the through hole 113 improves the infiltration efficiency of the pole piece 11. Small.

After in-depth research and extensive experiments, the inventor found that K ₁ /(W+K ₁ +K ₂ ) should be limited to 3%-32%, and K ₂ /(W+K ₁ +K ₂ ) should be limited to 3%-32%. 3%-32% to improve the wetting efficiency of the pole piece 11 and reduce the risk of breakage of the current collector 111.

In some embodiments _, in the first direction

The smaller K ₁ is, the smaller the distance between the edge of the first non-porous area 1112 and the opening area 1111 is. When the current collector 111 is pulled, the higher the risk of microcracks on the first non-porous area 1112 extending to the through hole 113 , the risk of breakage of the current collector 111 is also higher. The larger K ₁ is, the smaller the area of the opening area 1111 is, the higher the difficulty for the electrolyte to pass through the opening area 1111 , and the smaller the improvement in the wetting efficiency of the pole piece 11 by the through hole 113 is.

After in-depth research and extensive experiments, the inventor found that limiting K ₁ to 10 mm to 100 mm can improve the infiltration efficiency of the pole piece 11 and reduce the risk of breakage of the current collector 111 .

In some embodiments, the dimension _K2 of the second non-porous area 1113 in the first direction

Figure 10 is a schematic structural diagram of a current collector according to other embodiments of the present application.

As shown in FIG. 10 , in some embodiments, the plurality of through holes 113 are arranged along the first direction X and the second direction Y. The first direction X, the second direction Y and the thickness direction Z of the current collector 111 are both perpendicular to each other.

In some embodiments, the opening area 1111 includes a plurality of rows of through holes 113 equidistantly arranged along the first direction X. Two adjacent rows of through holes 113 may be offset in the second direction Y.

According to some embodiments of the present application, the present application also provides an electrode assembly, including the pole piece of any of the above embodiments.

According to some embodiments of the present application, the present application also provides a battery cell, including a casing and the electrode assembly of any of the above embodiments, and the electrode assembly is accommodated in the casing.

According to some embodiments of the present application, the present application also provides a battery including a plurality of battery cells according to any of the above embodiments.

According to some embodiments of the present application, the present application also provides an electrical device, including the battery cell of any of the above embodiments, and the battery cell is used to provide electrical energy to the electrical device. The power-consuming device can be any of the aforementioned devices or systems using battery cells.

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

The current collector 111 includes an opening region 1111, a first non-porous region 1112, a second non-porous region 1113 and a tab 1112a. The first non-porous region 1112 and the second non-porous region 1113 are respectively located in the opening region 1111 along the first direction. On both sides of X, the tabs 1112a protrude from the edge of the first non-hole area 1112 away from the hole area 1111. The opening area 1111 is provided with a plurality of through holes 113 , and neither the first non-porous area 1112 nor the second non-porous area 1113 is provided with a through hole 113 .

The opening area 1111, the first non-porous area 1112 and the second non-porous area 1113 are coated with the active material layer 112, and at least part of the tab 1112a is not coated with the active material layer 112.

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

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

The present application will be further described below in conjunction with the examples.

In order to make the invention purpose, technical solutions and beneficial technical effects of the present application clearer, the present application will be further described in detail below in conjunction with examples. However, it should be understood that the embodiments of the present application are only for explaining the present application and are not intended to limit the present application, and the embodiments of the present application are not limited to the embodiments given in the specification. If the specific experimental conditions or operating conditions are not specified in the examples, they are made according to conventional conditions, or according to the conditions recommended by the material supplier.

Example 1:

(i) Provide a long steel foil with a length L of 3000m, a width _W0 of 320mm, and a thickness T of 10μm.

(ii) Open circular through-holes arranged in an array on the steel foil, and the diameter D of the through-holes is 20 μm. The through holes are in array shape. Specifically, 1750 rows of through holes were opened on the steel foil, and the 1750 rows of through holes were arranged at equal intervals along the width direction of the steel foil; in the width direction, the distance D ₁ between two adjacent through holes was 100 μm. Each row of through holes is arranged at equal intervals in the length direction. In the length direction, the distance _D2 between two adjacent through holes is 100 μm; in the length direction, each row of through holes is arranged to both ends of the steel foil.

After the through holes are opened, the steel foil forms a current collector. The current collector includes an edge area 1114 arranged along the width direction, an opening area 1111 and a second non-porous area 1113. As shown in FIG. 11 , in the width direction, the width K ₀ of the edge area 114 is 60 mm, the width W of the hole area is 210 mm, and the width K ₂ of the second non-hole area is 50 mm.

(iii) Follow steps (i) and (ii) above to prepare 10 current collectors.

(iv) Cut a sample from the open area of a current collector. The size of the sample in the length direction of the current collector is 100mm and the size in the width direction of the current collector is 20mm. Install the sample on the tensile machine, and turn on the tensile machine. The tensile machine stretches the sample at 50mm/min. Record the corresponding force when the sample breaks as F (unit N); calculate the tensile force of the sample in the length direction of the current collector. Tensile strength P=F/(20mm×0.01mm).

(v) 10 current collectors are sequentially subjected to processes such as coating, rolling, and cutting to prepare multiple pole pieces. As shown in Figure 12, the length _L1 of the pole piece is 3400 mm, and the width _W1 of the active material layer (in Figure 12, the active material layer is indicated by a hatched line) is 310mm. The edge area is cut to form a first non-hole area and a pole tab. The width K ₁ of the first non-hole area is 50 mm, and the width W ₂ of the pole tab is 10 mm.

During the preparation process of the pole piece, the number of current collector fractures was recorded, and the fracture rate M of the current collector was calculated. The unit of fracture rate M is times/1000m, that is, the number of fractures per 1000m of current collector travel.

(vi) The prepared pole pieces are rolled, put into the shell, and injected with liquid to prepare 20 battery cells. After the liquid injection is completed, put the 20 battery cells at rest, then disassemble one battery cell every 20 minutes, and observe the infiltration status of the disassembled pole pieces (you can judge whether the area is infiltrated by observing the color of the pole pieces). ) until the completely soaked pole pieces are removed, and record the length of time the corresponding battery cell has been left standing. This time can represent the length of time the pole pieces are completely soaked.

Example 2-8: For the test method of Example 2-8, refer to Example 1. The differences between Example 2-8 and Example 1 are as shown in Table 1.

Comparative Example 1-3: For the test method of Comparative Example 1-3, refer to Example 1. The differences between Comparative Example 1-3 and Example 1 are as shown in Table 1.

It should be added here that in Comparative Example 3, the diameter of the through hole is 0, that is to say, there is no through hole in the current collector of Comparative Example 3. The length of time for the pole piece of Comparative Example 3 to be completely infiltrated is Q.

Table 1

Referring to Examples 1-8 and Comparative Example 3, through holes are opened on the current collector to form a channel for the electrolyte to pass through, thereby improving the infiltration efficiency of the pole pieces, improving the consistency of the infiltration of the pole pieces, and improving the efficiency of the battery cells. cycle performance. Referring to Examples 1-8 and Comparative Examples 1-2, limiting the tensile strength of the opening area in the length direction to greater than or equal to 100 MPa can reduce the risk of breakage of the current collector.

The inventor has also conducted the above experiments on aluminum current collectors, copper current collectors, nickel current collectors, etc., and found that they can also reduce the risk of current collector fracture when the tensile strength is limited to greater than or equal to 100Mpa.

Example 9:

(i) Provide a long steel foil with a length L of 3000m, a width _W0 of 320mm, and a thickness T of 10μm.

(ii) Open circular through-holes arranged in an array on the steel foil, and the diameter D of the through-holes is 50 μm. The through holes are in array shape. Specifically, 1500 rows of through holes were opened on the steel foil, and the 1500 rows of through holes were arranged at equal intervals along the width direction of the steel foil; in the width direction, the distance D ₁ between two adjacent through holes was 90 μm. Each row of through holes is arranged at equal intervals in the length direction. In the length direction, the distance _D2 between two adjacent through holes is 90 μm; in the length direction, each row of through holes is arranged to both ends of the steel foil.

After the through holes are formed, the steel foil forms a current collector, which includes an edge region, an opening region, and a second non-porous region arranged along the width direction. As shown in FIG11 , in the width direction, the width K ₀ of the edge region is 60 mm, the width W of the opening region is 210 mm, and the width K ₂ of the second non-porous region is 50 mm.

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

(iii) Follow steps (i) and (ii) above to prepare 10 current collectors.

(iv) Put 10 current collectors through coating, rolling, cutting and other processes in sequence to prepare multiple pole pieces. As shown in Figure 12, the length L ₁ of the pole piece is 3400 mm, and the width W ₁ of the active material layer is 310 mm. The edge area is cut to form a first non-hole area and a pole tab. The width K ₁ of the first non-hole area is 50 mm, and the width W ₂ of the pole tab is 10 mm.

During the preparation process of the pole piece, the number of current collector fractures was recorded, and the fracture rate M of the current collector was calculated. The unit of fracture rate M is times/1000m, that is, the number of fractures per 1000m of current collector travel.

(v) The prepared pole pieces are rolled, put into the shell, and injected with liquid to prepare 20 battery cells. After the liquid injection is completed, put the 20 battery cells at rest, then disassemble one battery cell every 20 minutes, and observe the infiltration status of the disassembled pole pieces (you can judge whether the area is infiltrated by observing the color of the pole pieces). ) until the completely soaked pole pieces are removed, and record the length of time the corresponding battery cell has been left standing. This time can represent the length of time the pole pieces are completely soaked.

Example 10-14: For the test method of Example 10-14, refer to Example 9. The differences between Example 10-14 and Example 9 are as shown in Table 2.

Comparative Example 4-7: For the test method of Comparative Example 4-7, refer to Example 9. The differences between Comparative Example 4-7 and Example 9 are as shown in Table 2. It should be added here that in Comparative Example 7, the diameter of the through hole is 0, that is to say, there is no through hole in the current collector of Comparative Example 7. The length of time for the pole piece of Comparative Example 7 to be completely infiltrated is Q.

Table 2

Referring to Examples 9-14 and Comparative Examples 5-7, through holes are opened on the current collector to form a channel for the electrolyte to pass through, thereby improving the infiltration efficiency of the pole pieces, improving the consistency of the infiltration of the pole pieces, and improving the battery Cycling performance of the monomer. Referring to Examples 9-14 and Comparative Examples 4-6, limiting the value of S1/S2 to 0.1-0.7 can improve the wetting efficiency of the pole piece and reduce the risk of breakage of the current collector.

Example 15:

(i) Provide a long steel foil with a length L of 3000m, a width _W0 of 320mm, and a thickness T of 10μm.

(ii) Open circular through-holes arranged in an array on the steel foil, and the diameter D of the through-holes is 50 μm. The through holes are in array shape. Specifically, 1400 rows of through holes were opened on the steel foil, and the 1400 rows of through holes were arranged at equal intervals along the width direction of the steel foil; in the width direction, the distance D ₁ between two adjacent through holes was 100 μm. Each row of through holes is arranged at equal intervals in the length direction. In the length direction, the distance _D2 between two adjacent through holes is 100 μm; in the length direction, each row of through holes is arranged to both ends of the steel foil.

The steel foil forms a current collector after completing the opening of the through holes. The current collector includes an edge area, an opening area and a second non-porous area arranged along the width direction. As shown in Figure 11, in the width direction, the width _K0 of the edge area is 60mm, the width W of the hole area is 210mm, and the width _K2 of the second non-hole area is 50mm.

(iii) Follow steps (i) and (ii) above to prepare 10 current collectors.

(iv) Put 10 current collectors through coating, rolling, cutting and other processes in sequence to prepare multiple pole pieces. As shown in Figure 12, the length L ₁ of the pole piece is 3400 mm, and the width W ₁ of the active material layer is 310 mm. The edge area is cut to form a first non-hole area and a pole tab. The width K ₁ of the first non-hole area is 50 mm, and the width W ₂ of the pole tab is 10 mm.

During the preparation process of the pole piece, the number of current collector fractures was recorded, and the fracture rate M of the current collector was calculated. The unit of fracture rate M is times/1000m, that is, the number of fractures per 1000m of current collector travel.

(v) The prepared pole pieces are rolled, put into the shell, and injected with liquid to prepare 20 battery cells. After the liquid injection is completed, put the 20 battery cells at rest, then disassemble one battery cell every 20 minutes, and observe the infiltration status of the disassembled pole pieces (you can judge whether the area is infiltrated by observing the color of the pole pieces). ) until the completely soaked pole pieces are removed, and record the length of time the corresponding battery cell has been left standing. This time can represent the length of time the pole pieces are completely soaked.

Example 16-19: For the test method of Example 16-19, refer to Example 15. The differences between Example 16-19 and Example 15 are as shown in Table 3.

Comparative Example 8-11: For the test method of Comparative Example 8-11, refer to Example 15. The differences between Comparative Example 8-11 and Example 15 are as shown in Table 3.

It should be added here that in Comparative Example 9, the diameter of the through hole is 0, that is to say, there is no through hole in the current collector of Comparative Example 9. The length of time for the pole piece of Comparative Example 9 to be completely infiltrated is Q.

In Examples 15-19 and Comparative Examples 8-11, the diameter D, spacing D ₁ and D ₂ of the through holes remain unchanged; when W changes, the number of rows of through holes is changed.

table 3

Referring to Examples 15-19 and Comparative Examples 8-9, through holes are opened on the current collector to form a channel for the electrolyte to pass through, thereby improving the infiltration efficiency of the pole pieces, improving the consistency of the infiltration of the pole pieces, and improving the battery Cycling performance of the monomer. Referring to Examples 15-19 and Comparative Examples 8-11, K ₁ /(W+K ₁ +K ₂ ) is limited to 3%-32%, and K ₂ /(W+K ₁ +K ₂ ) is limited to 3 %-32% to improve the wetting efficiency of the pole piece and reduce the risk of current collector breakage.

It should be noted that, as long as there is no conflict, the embodiments and features in the embodiments of this application can be combined with each other.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be Modifications may be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions may be made to some of the technical features, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions in the embodiments of the present application.

Claims (23)

1. A current collector, used for pole pieces, includes an opening 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 area, the first non-porous area is located on one side of the opening area along the first direction; A non-porous area is not provided with the through holes;

   The first direction is perpendicular to the thickness direction of the current collector.
4. The current collector according to claim 3, further comprising a pole protruding from an edge of the first non-porous region away from the opening 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 two perpendicular to each other.
6. The current collector of claim 5, wherein the tensile strength of the first non-porous region in the second direction 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 opening region 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 area, the second non-porous area is located in the open area away from the first non-porous area. On one side of the second non-hole area, the through hole is not provided.
9. The pole piece according to claim 8, wherein in the first direction, the size of the opening area is W, the size of the first non-porous area is K 1 , and the size of the second non-porous area is K ₁ The size of is K ₂ ; W, K ₁ and K ₂ satisfy:

   3%≤K ₁ /(W+K ₁ +K ₂ )≤32%, 3%≤K ₂ /(W+K ₁ +K ₂ )≤32%.
10. The pole piece according to claim 8 or 9, wherein, in the first direction, a 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 S ₁ , the total area of the opening area is S ₂ , and S ₁ and S ₂ satisfy: 0.1 ≤S ₁ /S ₂ ≤0.7.
12. The current collector according to claim 11, wherein S ₁ and S ₂ satisfy: 0.3≤S ₁ /S ₂ ≤0.7.
13. The current collector according to any one of claims 1-12, wherein the diameter of the through hole is 0.02mm-2mm.
14. The current collector according to claim 13, wherein the diameter of the through hole is 0.2mm-0.5mm.
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 1-16, wherein the plurality of through holes are arranged in an array along the first direction and the second direction;

    The first direction, the second direction and the thickness direction of the current collector are two perpendicular to each other.
18. A pole piece including:

    The current collector according to any one of claims 1-17; and

    An active material layer is coated on the surface of the current collector and covers the opening area.
19. A pole piece including:

    The current collector according to any one of claims 8-10; and

    An active material layer is coated on the opening area, the first non-porous area and the second non-porous area.
20. An electrode assembly comprising the pole piece according to claim 18 or 19.
21. A battery cell including:

    casing; and

    The electrode assembly according to claim 20, housed in the housing.
22. A battery including a plurality of battery cells according to claim 21.
23. An electrical device includes the battery cell according to claim 21, wherein the battery cell is used to provide electrical energy.

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