Composite current collector, pole piece, battery and electric equipment

Abstract

The utility model belongs to the technical field of batteries, and particularly relates to a composite current collector, a pole piece, a battery and electric equipment, the composite current collector comprises a first metal layer, a second metal layer and an insulating layer, the insulating layer is arranged between the first metal layer and the second metal layer, a hollow part is arranged on the insulating layer, and the first metal layer and the second metal layer are arranged on the hollow part. Along the thickness direction of the insulating layer, the hollow part comprises a first accommodating cavity and a second accommodating cavity from top to bottom, the first accommodating cavity and the second accommodating cavity are distributed in a staggered manner and have a first overlapping area, the first accommodating cavity and the second accommodating cavity are communicated with each other through the first overlapping area, and the second accommodating cavity and the first overlapping area are communicated with each other through the second overlapping area; the hollow part is filled with a conducting medium, and the first metal layer is electrically connected with the second metal layer through the conducting medium; the conductive medium is effectively locked in the first containing cavity and the second containing cavity, and the situation that the conductive medium loses mechanical support in the straight-through hole and is prone to falling off due to curvature change of the composite current collector is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of batteries, and specifically relates to a composite current collector, a pole piece, a battery and electrical equipment. Background Art

[0002] As a new type of secondary battery, lithium-ion battery has the advantages of high energy density and power density, high operating voltage, light weight, small size, long cycle life, good safety, and green environmental protection. It has broad application prospects in portable appliances, power tools, large-scale energy storage, electric transportation power supply, etc.

[0003] The energy density of a battery is one of the important indicators for evaluating battery performance. It directly determines the amount of electricity that a battery can store at the same weight or volume, thus affecting the battery's endurance and performance. When the battery size is constant, in order to increase the energy density of the battery, it is generally necessary to use active materials with higher specific capacity or to reduce the weight of inactive materials as much as possible. In a battery, active materials, shells, foils, and electrolytes account for a high proportion of the battery weight.

[0004] At present, in order to reduce the weight of foil and increase the energy density of batteries, composite foil is widely used. Composite foil includes two metal layers and a polymer layer arranged between the two metal layers. In order to achieve conductive connection between the two metal layers, a through hole is usually arranged on the polymer layer and a conductive material is filled in the through hole.

[0005] However, for wound cells, the composite foil in the pole piece will form different degrees of curvature during the winding process. This change in curvature causes the conductive material filled in the through hole to lose mechanical support and cannot be stably fixed in the hole, making it very easy to fall off. Especially when the lithium battery undergoes repeated charge and discharge cycles, the pole piece will be affected by the expansion force, which further aggravates the problem of conductive material falling off and may even cause serious safety risks such as battery fire. Utility Model Content

[0006] The purpose of the utility model is to provide a composite current collector, a pole piece, a battery and an electrical device to address the deficiencies of the prior art, and to solve the technical problem in the prior art that the curvature of the composite foil changes during the winding process, causing the conductive material to lose mechanical support in the through hole and easily fall off.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] In the first aspect, the utility model provides a composite current collector, comprising a first metal layer, a second metal layer and an insulating layer, wherein the insulating layer is arranged between the first metal layer and the second metal layer, and a hollow portion is arranged on the insulating layer, and along the thickness direction of the insulating layer, the hollow portion comprises a first accommodating cavity and a second accommodating cavity from top to bottom, the first accommodating cavity and the second accommodating cavity are staggered and have a first overlapping area, the first accommodating cavity and the second accommodating cavity are connected to each other through the first overlapping area, the hollow portion is filled with a conductive medium, and the first metal layer is electrically connected to the second metal layer through the conductive medium.

[0009] Preferably, a first center distance a of the orthographic projections of the first accommodating cavity and the second accommodating cavity on the same horizontal plane satisfies the relationship: 0.2D1≤a≤0.5D1;

[0010] And / or, 0.2D2≤a≤0.5D2; wherein D1 is the first dimension of the first accommodating cavity, D2 is the second dimension of the second accommodating cavity, and the first dimension D1 of the first accommodating cavity and the second dimension D2 of the second accommodating cavity are both on the same straight line with the first center distance a.

[0011] Preferably, the depth b1 of the first accommodating cavity and the thickness T of the insulating layer satisfy the relationship: 0.25T≤b1≤0.75T;

[0012] And / or, the depth b2 of the second accommodating cavity and the thickness T of the insulating layer satisfy the relationship: 0.25T≤b2≤0.75T.

[0013] Preferably, the depth b1 of the first accommodating cavity is the same as the depth b2 of the second accommodating cavity.

[0014] Preferably, a plurality of the hollow portions are provided, and the plurality of the hollow portions are arranged in an array on the insulating layer.

[0015] Preferably, along the length direction of the insulating layer, the central axes L3 of the hollow portions located in the same row are parallel to each other; and / or, along the width direction of the insulating layer, the central axes L3 of the hollow portions located in the same column are parallel to each other;

[0016] The central axis L1 of the first accommodating cavity and the central axis L2 of the second accommodating cavity located in the same hollow portion are parallel to each other.

[0017] Preferably, along the length direction of the insulating layer, a second center distance d1 of the orthographic projections of two adjacent first accommodating cavities on the same horizontal plane and a third center distance d2 of the orthographic projections of two adjacent second accommodating cavities on the same horizontal plane satisfy the relationship: 2M1≤d1≤4M1, 2M2≤d2≤4M2, wherein M1 is the maximum dimension of the first accommodating cavity in the length direction of the insulating layer, and M2 is the maximum dimension of the second accommodating cavity in the length direction of the insulating layer;

[0018] And / or, along the width direction of the insulating layer, the fourth center distance f1 of the orthographic projections of two adjacent first accommodating cavities on the same horizontal plane and the fifth center distance f2 of the orthographic projections of two adjacent second accommodating cavities on the same horizontal plane satisfy the relationship: 3N1≤f1≤5N1, 3N2≤f2≤5N2, wherein N1 is the maximum dimension of the first accommodating cavity in the width direction of the insulating layer, and N2 is the maximum dimension of the second accommodating cavity in the width direction of the insulating layer.

[0019] Preferably, the first accommodating cavity of one of the two adjacent hollow parts and the second accommodating cavity of the other of the two adjacent hollow parts have a second overlapping area, and the two adjacent hollow parts are connected to each other through the second overlapping area.

[0020] Preferably, the hollow portion passes through the first metal layer and the second metal layer, a third metal layer is provided on a side wall of the hollow portion, and the third metal layer connects the first metal layer and the second metal layer.

[0021] In a second aspect, the utility model provides a pole piece, comprising an active material layer and the composite current collector described in the above embodiment, wherein the active material layer is arranged on at least one side of the composite current collector.

[0022] In a third aspect, the utility model provides a battery, comprising a housing and a battery cell accommodated in the housing, wherein the battery cell comprises the pole piece described in the above embodiment.

[0023] In a fourth aspect, the utility model provides an electrical device, comprising the battery described in the above embodiment.

[0024] Compared with the prior art, the beneficial effects achieved by the utility model are:

[0025] The utility model provides a composite current collector, which is used in conjunction with a first metal layer, a second metal layer and an insulating layer. The insulating layer is arranged between the first metal layer and the second metal layer, and the hollow portion on the insulating layer is filled with a conductive medium, so that the first metal layer can be electrically connected to the second metal layer through the conductive medium, effectively realizing the conductive connection between the first metal layer and the second metal layer, thereby reducing the internal resistance of the battery itself and improving the charging cycle effect of the battery. In addition, the first accommodating cavity and the second accommodating cavity of the hollow portion are staggered and have a first overlapping area. The first accommodating cavity and the second accommodating cavity are interconnected through the first overlapping area, effectively making the first accommodating cavity and the second accommodating cavity both have a supporting surface, thereby locking the conductive medium in the first accommodating cavity and the second accommodating cavity, avoiding the conductive medium from losing mechanical support in the straight-through hole due to the change in curvature of the composite current collector during the winding process and being easy to fall off. And when the pole piece is subjected to the expansion force, the risk of the conductive medium falling off is reduced, thereby improving the safety performance of the battery.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 This is one of the structural schematic diagrams of the pole piece of the utility model.

[0029] Figure 2 This is the second structural schematic diagram of the pole piece of the utility model.

[0030] Figure 3 for Figure 2 Schematic diagram of the enlarged structure at point A in the middle.

[0031] Figure 4 This is one of the structural schematic diagrams of the insulating layer of the utility model.

[0032] Figure 5 This is the second structural schematic diagram of the insulating layer of the utility model.

[0033] Figure 6 This is the third structural schematic diagram of the insulating layer of the utility model.

[0034] Figure 7 This is the fourth structural schematic diagram of the insulating layer of the utility model.

[0035] Figure 8 This is the fifth structural schematic diagram of the insulating layer of the utility model.

[0036] The reference numerals are described as follows:

[0037] 100, pole piece;

[0038] 10. composite current collector; 11. insulating layer; 111. hollow portion; 1111. first accommodation cavity; 1112. second accommodation cavity; 1113. first overlapping region; 1114. second overlapping region; 12. conductive medium; 13. first metal layer; 14. second metal layer; 15. third metal layer;

[0039] 20. Active material layer;

[0040] h, length direction of the insulating layer; g, width direction of the insulating layer; k, thickness direction of the insulating layer. DETAILED DESCRIPTION

[0041] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. For example, "including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0042] Furthermore, the terms “first”, “second”, etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

[0043] In the utility model, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the utility model can be understood according to the specific circumstances.

[0044] In the utility model, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the utility model generally indicates that the associated objects before and after are in an "or" relationship.

[0045] The following will be combined with the attached Figures 1 to 8 The technical solutions in the embodiments of the utility model are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0046] The electrical equipment of the embodiment of the utility model includes a battery. The electrical equipment may be a car, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The car may be a fuel car, a gas car, or a new energy car, and the new energy car may be a pure electric car, a hybrid car, or an extended-range car, and the like; the spacecraft includes an airplane, a rocket, a space shuttle, and a spacecraft, and the like; the electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like; the 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, and the like. The embodiment of the present application does not impose any special restrictions on the above-mentioned electrical equipment.

[0047] The battery of the embodiment of the utility model comprises a housing and a battery cell accommodated in the housing. The battery cell comprises a wound pole piece 100 and a diaphragm.

[0048] See also Figures 1-2 The pole piece 100 of the embodiment of the utility model includes an active material layer 20 and a composite current collector 10 , and the active material layer 20 is arranged on at least one side of the composite current collector 10 .

[0049] Specifically, the electrode sheet 100 includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet includes a positive electrode active material layer and a positive electrode composite current collector, and the positive electrode active material layer is arranged on at least one side of the positive electrode composite current collector. The negative electrode sheet includes a negative electrode active material layer and a negative electrode composite current collector, and the negative electrode active material layer is arranged on at least one side of the negative electrode composite current collector.

[0050] See also Figures 1 to 8The composite current collector 10 of the embodiment of the utility model includes a first metal layer 13, a second metal layer 14 and an insulating layer 11, wherein the insulating layer 11 is arranged between the first metal layer 13 and the second metal layer 14, and a hollow portion 111 is arranged on the insulating layer 11, and along the thickness direction k of the insulating layer 11, the hollow portion 111 includes a first accommodating cavity 1111 and a second accommodating cavity 1112 from top to bottom, the first accommodating cavity 1111 and the second accommodating cavity 1112 are staggered and have a first overlapping area 1113, the first accommodating cavity 1111 and the second accommodating cavity 1112 are connected to each other through the first overlapping area 1113, and the hollow portion 111 is filled with a conductive medium 12, and the first metal layer 13 is electrically connected to the second metal layer 14 through the conductive medium 12.

[0051] Compared with the prior art, the composite current collector 10 of the embodiment of the utility model is used in combination with the first metal layer 13, the second metal layer 14 and the insulating layer 11. The insulating layer 11 is arranged between the first metal layer 13 and the second metal layer 14. The hollow portion 111 on the insulating layer 11 is filled with a conductive medium 12, so that the first metal layer 13 can be electrically connected to the second metal layer 14 through the conductive medium 12, effectively realizing the conductive connection between the first metal layer 13 and the second metal layer 14, thereby reducing the internal resistance of the battery itself and improving the charging cycle effect of the battery. In addition, the first accommodation cavity 1111 and the second accommodation cavity 1112 of the hollow portion 111 are staggered and have a first overlapping area 1113. The first accommodation cavity 1111 and the second accommodation cavity 1112 are connected to each other through the first overlapping area 1113, which effectively makes the first accommodation cavity 1111 and the second accommodation cavity 1112 have a support surface, thereby locking the conductive medium 12 in the first accommodation cavity 1111 and the second accommodation cavity 1112, avoiding the conductive medium 12 from losing mechanical support in the through hole and falling off easily due to the curvature change of the composite current collector 10 during the winding process. And when the pole piece 100 is subjected to the expansion force, the risk of the conductive medium 12 falling off is reduced, thereby improving the safety performance of the battery.

[0052] It can be understood that, compared with the existing current collectors using copper foil or aluminum foil, the composite current collector 10 of the present invention can effectively reduce the weight of the battery cell, improve the energy density of the battery, and reduce the cost of raw materials.

[0053] See also Figures 4 to 6In some embodiments, the first center distance a of the orthographic projections of the first accommodating cavity 1111 and the second accommodating cavity 1112 on the same horizontal plane satisfies the relationship: 0.2D1≤a≤0.5D1; and / or, 0.2D2≤a≤0.5D2; wherein D1 is the first dimension of the first accommodating cavity 1111, D2 is the second dimension of the second accommodating cavity 1112, and the first dimension D1 of the first accommodating cavity 1111 and the second dimension D2 of the second accommodating cavity 1112 are both located on the same straight line as the first center distance a. By setting the first center distance a, the first center distance a cannot be too large or too small. When the first center distance a is too small, the first overlapping area 1113 of the first accommodating cavity 1111 and the second accommodating cavity 1112 is large, so that the supporting surface of the first accommodating cavity 1111 and the supporting surface of the second accommodating cavity 1112 are small, resulting in poor locking effect of the first accommodating cavity 1111 and the second accommodating cavity 1112 on the conductive medium 12, thereby causing the conductive medium 12 to fall off. When the first center distance a is too large, the first overlapping area 1113 of the first accommodating cavity 1111 and the second accommodating cavity 1112 is small, resulting in poor conductivity between the first metal layer 13 and the second metal layer 14, thereby increasing the internal resistance of the battery itself and reducing the charging cycle effect of the battery; or the first accommodating cavity 1111 and the second accommodating cavity 1112 do not have a first overlapping area, resulting in the inability to achieve an effective electron path between the first metal layer 13 and the second metal layer 14.

[0054] Therefore, the first center distance a satisfies the relationship: 0.2D1≤a≤0.5D1; and / or, 0.2D2≤a≤0.5D2. This can not only achieve electrical connection between the first metal layer 13 and the second metal layer 14, ensuring the conductive effect between the first metal layer 13 and the second metal layer 14, but also ensure the locking effect of the first accommodating cavity 1111 and the second accommodating cavity 1112 on the conductive medium 12, preventing the conductive medium 12 from falling off.

[0055] See also Figure 3In some embodiments, the depth b1 of the first accommodating cavity 1111 and the thickness T of the insulating layer 11 satisfy the relationship: 0.25T≤b1≤0.75T; and / or, the depth b2 of the second accommodating cavity 1112 and the thickness T of the insulating layer 11 satisfy the relationship: 0.25T≤b2≤0.75T. By setting the depth b1 of the first accommodating cavity 1111 and the depth b2 of the second accommodating cavity 1112, the depth b1 of the first accommodating cavity 1111 and / or the depth b2 of the second accommodating cavity 1112 cannot be too large or too small. When the depth b1 of the first accommodating cavity 1111 and / or the depth b2 of the second accommodating cavity 1112 are too small, the storage capacity of the first accommodating cavity 1111 and / or the second accommodating cavity 1112 is small, so that the amount of the conductive medium 12 is small, resulting in poor conductivity between the first metal layer 13 and the second metal layer 14, thereby increasing the internal resistance of the battery itself and reducing the charging cycle effect of the battery. When the depth b1 of the first accommodating cavity 1111 and / or the depth b2 of the second accommodating cavity 1112 is too large, that is, the depth b1 of the first accommodating cavity 1111 and / or the depth b2 of the second accommodating cavity 1112 is equal to the thickness T of the insulating layer 11, the conductive medium 12 loses mechanical support in the first accommodating cavity 1111 and / or the second accommodating cavity 1112 and is easy to fall off.

[0056] Therefore, the depth b1 of the first accommodation cavity 1111 satisfies the relationship: 0.25T≤b1≤0.75T; and / or the depth b2 of the second accommodation cavity 1112 satisfies the relationship: 0.25T≤b2≤0.75T. This can not only ensure the conductive effect between the first metal layer 13 and the second metal layer 14, but also ensure the locking effect of the first accommodation cavity 1111 and the second accommodation cavity 1112 on the conductive medium 12, thereby preventing the conductive medium 12 from falling off.

[0057] It can be understood that when the sum of the depth b1 of the first accommodation cavity 1111 and the depth b2 of the second accommodation cavity 1112 is less than the thickness T of the insulating layer 11, that is, 0<b1+b2<T, the hollow portion 111 has a channel connecting the first accommodation cavity 1111 and the second accommodation cavity 1112 in the first overlapping area 1113 to ensure the connection between the first accommodation cavity 1111 and the second accommodation cavity 1112, thereby ensuring that the first metal layer 13 and the second metal layer 14 can be electrically connected through the conductive medium 12. When the sum of the depth b1 of the first accommodation cavity 1111 and the depth b2 of the second accommodation cavity 1112 is equal to the thickness T of the insulating layer 11, that is, b1+b2=T, the bottom wall of the first accommodation cavity 1111 and the bottom wall of the second accommodation cavity 1112 contact and communicate with each other in the first overlapping area. At this time, the depth b1 of the first accommodation cavity 1111 and the depth b2 of the second accommodation cavity 1112 have the following settings:

[0058] The first setting mode: the depth b1 of the first accommodating cavity 1111 is less than the depth b2 of the second accommodating cavity 1112, that is, b1<b2. For example, when b1=0.25T, b2=0.75T; when b1=0.3T, b2=0.7T; when b1=0.35T, b2=0.65T; when b1=0.4T, b2=0.6T; when b1=0.45T, b2=0.55T.

[0059] The second configuration: the depth b2 of the second accommodation cavity 1112 is less than the depth b1 of the first accommodation cavity 1111, that is, b2 < b1. For example, when b2 = 0.25T, b1 = 0.75T; when b2 = 0.3T, b1 = 0.7T; when b2 = 0.35T, b1 = 0.65T; when b2 = 0.4T, b1 = 0.6T; when b2 = 0.45T, b1 = 0.55T.

[0060] The third configuration: the depth b1 of the first accommodating cavity 1111 is the same as the depth b2 of the second accommodating cavity 1112, that is, b1 = b2. For example, when b2 = 0.5T, b1 = 0.5T.

[0061] It is understandable that, since the coating amount of the positive active material layer of the positive electrode sheet is large and the compaction density of the positive electrode sheet is high, if the positive composite current collector is too thin, it is easy to break during the rolling process. Therefore, in order to avoid the positive composite current collector from breaking during the rolling process and ensure the quality of the positive electrode sheet, the thickness of the insulating layer 11 of the positive composite current collector is greater than the thickness of the insulating layer 11 of the negative composite current collector.

[0062] Specifically, when the composite current collector 10 is a positive electrode composite current collector, the insulating layer 11 is a positive electrode insulating layer 11, the first accommodating cavity 1111 is a first positive electrode accommodating cavity, and the second accommodating cavity 1112 is a second positive electrode accommodating cavity, wherein the thickness of the positive electrode insulating layer 11 is 6 to 12 μm, the depth of the first positive electrode accommodating cavity is 3 to 6 μm, and the depth of the second positive electrode accommodating cavity is 3 to 6 μm. For example, when the thickness of the positive electrode insulating layer 11 is 6 μm, the depth of the first positive electrode accommodating cavity and the depth of the second positive electrode accommodating cavity are both 3 μm; when the thickness of the positive electrode insulating layer 11 is 12 μm, the depth of the first positive electrode accommodating cavity and the depth of the second positive electrode accommodating cavity can be both 3 μm, 4 μm, 5 μm or 6 μm, or the depth of the first positive electrode accommodating cavity is 3 μm, and the depth of the second positive electrode accommodating cavity is 4 μm, 5 μm or 6 μm. Of course, the depth of the first positive electrode accommodating cavity and the depth of the second positive electrode accommodating cavity are not limited to the listed values. Within the numerical range of the depth of the first positive electrode accommodating cavity and the depth of the second positive electrode accommodating cavity, any value that satisfies the sum of the depth of the first positive electrode accommodating cavity and the depth of the second positive electrode accommodating cavity is less than or equal to the thickness of the positive electrode insulating layer 11 is acceptable.

[0063] When the composite current collector 10 is a negative electrode composite current collector, the insulating layer 11 is a negative electrode insulating layer 11, the first accommodation cavity 1111 is a first negative electrode accommodation cavity, and the second accommodation cavity 1112 is a second negative electrode accommodation cavity, wherein the thickness of the negative electrode insulating layer 11 is 4 to 8 μm, the depth of the first negative electrode accommodation cavity is 2 to 4 μm, and the depth of the second negative electrode accommodation cavity is 2 to 4 μm. For example, when the thickness of the negative electrode insulating layer 11 is 4 μm, the depth of the first negative electrode accommodation cavity and the depth of the second negative electrode accommodation cavity are both 2 μm; when the thickness of the negative electrode insulating layer 11 is 8 μm, the depth of the first negative electrode accommodation cavity and the depth of the second negative electrode accommodation cavity can be both 2 μm, 3 μm or 4 μm, or the depth of the first negative electrode accommodation cavity is 2 μm, and the depth of the second negative electrode accommodation cavity is 3 μm or 4 μm. Of course, the depth of the first negative electrode accommodating cavity and the depth of the second negative electrode accommodating cavity are not limited to the listed values. Within the numerical range of the depth of the first negative electrode accommodating cavity and the depth of the second negative electrode accommodating cavity, any value that satisfies the sum of the depth of the first negative electrode accommodating cavity and the depth of the second negative electrode accommodating cavity is less than or equal to the thickness of the negative electrode insulating layer 11 is acceptable.

[0064] See also Figures 1 to 8 In some embodiments, a plurality of hollow portions 111 are provided, and the plurality of hollow portions 111 are arranged in an array on the insulating layer 11. By providing a plurality of hollow portions 111 on the insulating layer 11, each hollow portion 111 is filled with a conductive medium 12, which effectively increases the contact points between the first metal layer 13 and the second metal layer 14 and the conductive medium 12, thereby improving the conductive effect between the first metal layer 13 and the second metal layer 14.

[0065] See also Figure 4 In some embodiments, along the length direction h of the insulating layer 11, the central axes L3 of the hollow portions 111 in the same row are parallel to each other; and / or, along the width direction g of the insulating layer 11, the central axes L3 of the hollow portions 111 in the same column are parallel to each other; wherein, the central axis L1 of the first accommodation cavity 1111 and the central axis L2 of the second accommodation cavity 1112 in the same hollow portion 111 are parallel to each other. By arranging the plurality of hollow portions 111 in the above manner, the expansion force on the conductive medium 12 filled in the hollow portion 111 is effectively made uniform, thereby avoiding the composite current collector 10 from being broken due to excessive local expansion force.

[0066] See also Figures 4 to 6In some embodiments, along the length direction h of the insulating layer 11, the second center distance d1 of the orthographic projections of two adjacent first accommodating cavities 1111 on the same horizontal plane and the third center distance d2 of the orthographic projections of two adjacent second accommodating cavities 1112 on the same horizontal plane satisfy the relationship: 2M1≤d1≤4M1, 2M2≤d2≤4M2, wherein M1 is the maximum size of the first accommodating cavity 1111 in the length direction h of the insulating layer 11, and M2 is the maximum size of the second accommodating cavity 1112 in the length direction h of the insulating layer 11. size; and / or, along the width direction g of the insulating layer 11, the fourth center distance f1 of the orthographic projections of two adjacent first accommodating cavities 1111 on the same horizontal plane and the fifth center distance f2 of the orthographic projections of two adjacent second accommodating cavities 1112 on the same horizontal plane satisfy the relationship: 3N1≤f1≤5N1, 3N2≤f2≤5N2, wherein N1 is the maximum size of the first accommodating cavity 1111 in the width direction g of the insulating layer 11, and N2 is the maximum size of the second accommodating cavity 1112 in the width direction g of the insulating layer 11. By setting the second center distance d1, the third center distance d2, the fourth center distance f1 and the fifth center distance f2, the distance between two adjacent hollow portions 111 is effectively controlled, thereby controlling the number of hollow portions 111 on the insulating layer 11. The number of hollow portions 111 cannot be too many or too few. When the number of hollow portions 111 is too large, the number of hollow portions 111 on the insulating layer 11 is large, resulting in poor structural strength of the insulating layer 11, which makes the insulating layer 11 easy to break during the winding process of the pole piece 100. When the number of hollow portions 111 is too small, the number of hollow portions 111 on the insulating layer 11 is small, resulting in fewer points where the first metal layer 13 and the second metal layer 14 contact the conductive medium 12, resulting in poor conductivity between the first metal layer 13 and the second metal layer 14.

[0067] In addition, by setting the second center distance d1, the third center distance d2, the fourth center distance f1 and the fifth center distance f2, it is possible to effectively avoid overlapping areas between two adjacent first accommodating cavities 1111 and / or overlapping areas between two adjacent second accommodating cavities 1112.

[0068] Specifically, the second center distance d1 and the third center distance d2 are both 2 to 50 mm. For example, the second center distance d1 and the third center distance d2 are both 2 mm, 5 mm, 10 mm, 12 mm, 20 mm, 25 mm, 28 mm, 30 mm, 35 mm, 38 mm, 40 mm, 45 mm or 50 mm, but are not limited to the listed values, and other values ​​within the numerical range are also applicable. And / or, the fourth center distance f1 and the fifth center distance f2 are both 2 to 50 mm. For example, the fourth center distance f1 and the fifth center distance f2 are both 2 mm, 4 mm, 10 mm, 15 mm, 20 mm, 23 mm, 26 mm, 30 mm, 32 mm, 38 mm, 40 mm, 47 mm or 50 mm, but are not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0069] In some embodiments, the insulating layer 11 is PP, PE, PET or PVC.

[0070] See also Figures 7-8 In some embodiments, the first accommodation cavity 1111 of one of the two adjacent hollow portions 111 and the second accommodation cavity 1112 of the other of the two adjacent hollow portions 111 have a second overlapping region 1114, and the two adjacent hollow portions 111 are interconnected through the second overlapping region 1114. By setting the second overlapping region 1114, the two adjacent hollow portions 111 can be interconnected through the second overlapping region 1114, effectively enabling the conductive medium 12 filled in the two adjacent hollow portions 111 to be electrically connected, thereby improving the conductive effect between the first metal layer 13 and the second metal layer 14, and improving the charging cycle effect of the battery.

[0071] In some embodiments, the cross-sectional shape of the first accommodation cavity 1111 and the cross-sectional shape of the second accommodation cavity 1112 are both square, rectangular, circular or elliptical. Preferably, the cross-sectional shape of the first accommodation cavity 1111 and the cross-sectional shape of the second accommodation cavity 1112 are both circular. The diameter of the first accommodation cavity 1111 and the diameter of the second accommodation cavity 1112 are 1 to 10 mm.

[0072] See also Figures 2-3In some embodiments, the hollow portion 111 penetrates the first metal layer 13 and the second metal layer 14, and the side wall of the hollow portion 111 is provided with a third metal layer 15, and the third metal layer 15 connects the first metal layer 13 and the second metal layer 14. By providing the third metal layer 15 on the side wall of the hollow portion 111, the third metal layer 15 is used to connect the first metal layer 13 and the second metal layer 14, and effectively realize the conductive connection between the first metal layer 13 and the second metal layer 14. In addition, since the hollow portion 111 penetrates the first metal layer 13 and the second metal layer 14, the conductive medium 12 filled in the hollow portion 111 will contact the active material layer 20, so the conductive medium 12 can be the same material as the active material layer 20, that is, the active material layer 20 is partially filled in the hollow portion 111. In this way, the adhesion between the active material layer 20 and the composite current collector 10 is effectively improved, and the stability of the battery cycle performance is improved.

[0073] Furthermore, the first metal layer 13, the second metal layer 14 and the third metal layer 15 are made of the same material. The conductive medium 12 may also be made of materials other than the active material layer 20, for example, the conductive medium 12 is one or more of nano-conductive carbon, graphene and carbon nanotubes.

[0074] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A composite current collector, characterized in that: The invention comprises a first metal layer (13), a second metal layer (14) and an insulating layer (11); the insulating layer (11) is arranged between the first metal layer (13) and the second metal layer (14); a hollow portion (111) is arranged on the insulating layer (11); along a thickness direction (k) of the insulating layer (11), the hollow portion (111) comprises a first accommodating cavity (1111) and a second accommodating cavity (1112) from top to bottom; the first accommodating cavity (1111) and the second accommodating cavity (1112) are staggered and have a first overlapping area (1113); the first accommodating cavity (1111) and the second accommodating cavity (1112) are connected to each other via the first overlapping area (1113); the hollow portion (111) is filled with a conductive medium (12); the first metal layer (13) is electrically connected to the second metal layer (14) via the conductive medium (12).

2. The composite current collector according to claim 1, characterized in that: A first center distance a of the orthographic projections of the first accommodating cavity (1111) and the second accommodating cavity (1112) on the same horizontal plane satisfies the relationship: 0.2D1≤a≤0.5D1; and / or, 0.2D2≤a≤0.5D2; Wherein, D1 is the first dimension of the first accommodating cavity (1111), D2 is the second dimension of the second accommodating cavity (1112), and the first dimension D1 of the first accommodating cavity (1111) and the second dimension D2 of the second accommodating cavity (1112) are both located on the same straight line as the first center distance a.

3. The composite current collector according to claim 1, characterized in that: The depth b1 of the first accommodating cavity (1111) and the thickness T of the insulating layer (11) satisfy the relationship: 0.25T≤b1≤0.75T; And / or, the depth b2 of the second accommodating cavity (1112) and the thickness T of the insulating layer (11) satisfy the relationship: 0.25T≤b2≤0.75T.

4. The composite current collector according to claim 1 or 3, characterized in that: The depth b1 of the first accommodating cavity (1111) and the depth b2 of the second accommodating cavity (1112) are the same.

5. The composite current collector according to claim 1, characterized in that: A plurality of the hollow portions (111) are provided, and the plurality of the hollow portions (111) are arranged in an array on the insulating layer (11).

6. The composite current collector according to claim 5, characterized in that: Along the length direction (h) of the insulating layer (11), the central axes L3 of the hollow portions (111) located in the same row are parallel to each other; and / or, along the width direction (g) of the insulating layer (11), the central axes L3 of the hollow portions (111) located in the same column are parallel to each other; Wherein, the central axis L1 of the first accommodating cavity (1111) and the central axis L2 of the second accommodating cavity (1112) located in the same hollow portion (111) are parallel to each other.

7. The composite current collector according to claim 5, characterized in that: Along the length direction (h) of the insulating layer (11), a second center distance d1 of the orthographic projections of two adjacent first accommodating cavities (1111) on the same horizontal plane and a third center distance d2 of the orthographic projections of two adjacent second accommodating cavities (1112) on the same horizontal plane satisfy the relationship: 2M1≤d1≤4M1, 2M2≤d2≤4M2, wherein M1 is the maximum dimension of the first accommodating cavity (1111) in the length direction (h) of the insulating layer (11), and M2 is the maximum dimension of the second accommodating cavity (1112) in the length direction (h) of the insulating layer (11); And / or, along the width direction (g) of the insulating layer (11), a fourth center distance f1 of the orthographic projections of two adjacent first accommodating cavities (1111) on the same horizontal plane and a fifth center distance f2 of the orthographic projections of two adjacent second accommodating cavities (1112) on the same horizontal plane satisfy the relationship: 3N1≤f1≤5N1, 3N2≤f2≤5N2, wherein N1 is the maximum dimension of the first accommodating cavity (1111) in the width direction (g) of the insulating layer (11), and N2 is the maximum dimension of the second accommodating cavity (1112) in the width direction (g) of the insulating layer (11).

8. The composite current collector according to claim 5, characterized in that: The first accommodating cavity (1111) of one of the two adjacent hollow portions (111) and the second accommodating cavity (1112) of the other of the two adjacent hollow portions (111) have a second overlapping area (1114), and the two adjacent hollow portions (111) are connected to each other via the second overlapping area (1114).

9. The composite current collector according to claim 1, characterized in that: The hollow portion (111) penetrates the first metal layer (13) and the second metal layer (14); a third metal layer (15) is provided on the side wall of the hollow portion (111); and the third metal layer (15) connects the first metal layer (13) and the second metal layer (14).

10. A pole piece, characterized in that: It comprises an active material layer (20) and the composite current collector according to any one of claims 1 to 9, wherein the active material layer (20) is arranged on at least one side of the composite current collector (10).

11. A battery, characterized in that: It comprises a shell and a battery cell accommodated in the shell, and the battery cell comprises the pole piece as claimed in claim 10.

12. An electrical equipment, characterized in that: Comprising the battery of claim 11.

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