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

Abstract

The utility model relates to a current collector, a pole piece, an electrode assembly, a battery monomer and a battery. The current collector comprises a middle insulating layer, two microporous layers and two metal layers. The intermediate insulating layer is configured to insulate and allow ions to pass therethrough. And the two microporous layers are respectively arranged on two opposite sides of the middle insulating layer. The two metal layers are respectively covered on two opposite sides of the two microporous layers, one metal layer is a positive electrode metal layer, and the other metal layer is a negative electrode metal layer. Wherein the metal layer is provided with a first micro-pore structure communicated with the outside, and each micro-pore layer is provided with a second micro-pore structure communicated with the middle insulating layer and the first micro-pore structure. According to the technical scheme of the invention, lithium ions can be migrated from the outside of the current collector and can also be migrated from the inside of the current collector, equivalently, a migration path of the lithium ions between the positive electrode active layer and the negative electrode active layer is added, the lithium ions are more uniformly distributed on the pole piece, the electrochemical reaction efficiency of the battery is improved, and the electrochemical performance of the battery is improved. And the battery performance can be improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to current collectors, pole pieces, electrode assemblies, battery cells and batteries. Background Art

[0002] As an important component in lithium-ion batteries, the current collector has the function of collecting the current generated by the active materials of lithium-ion batteries to form a larger current output. In traditional lithium-ion batteries, the current collector is mostly made of metal foil such as copper foil and aluminum foil. Metal foil does not contribute to the transmission of lithium ions, so that lithium ions can only be transmitted unilaterally through the outside of the current collector. The lithium ion transmission path is too long, which can easily lead to uneven lithium extraction and insertion of the pole piece, affecting the battery performance. Utility Model Content

[0003] Based on this, it is necessary to provide a current collector, pole piece, electrode assembly, battery cell and battery to address the problem that the lithium ion transmission path of traditional batteries is too long, which easily leads to uneven distribution of lithium ions in the pole piece and affects battery performance.

[0004] A current collector, comprising:

[0005] an intermediate insulating layer, the intermediate insulating layer being configured to be insulating and allow ion penetration;

[0006] Two microporous layers are respectively arranged on opposite sides of the intermediate insulating layer; and,

[0007] Two metal layers are respectively covered on opposite sides of the two microporous layers, one of the metal layers is a positive electrode metal layer, and the other metal layer is a negative electrode metal layer;

[0008] Each of the metal layers has a first microporous structure connected to the outside, and each of the microporous layers has a second microporous structure connected to the intermediate insulating layer and each of the first microporous structures.

[0009] In some embodiments, the metal layer is sprayed on the microporous layer and deposited to form the first microporous structure.

[0010] In some embodiments, the spraying thickness of the metal layer is 1 μm-2 μm.

[0011] In some embodiments, each of the microporous layers has a thickness of 2 μm-8 μm.

[0012] In some embodiments, the pore size of the second microporous structure is 3 μm-4 μm.

[0013] In some embodiments, the intermediate insulating layer and the microporous layer are both high molecular polymer layers.

[0014] In some embodiments, the intermediate insulating layer is a Kevlar film layer having nanopores; and / or the microporous layer is a polyimide layer.

[0015] A pole piece, comprising:

[0016] A current collector as described in any of the above embodiments;

[0017] A positive electrode active layer, covering the positive electrode metal layer; and

[0018] The negative electrode active layer is covered on the negative electrode metal layer.

[0019] An electrode assembly comprises a diaphragm and the pole pieces as described in the embodiment, wherein the diaphragm is arranged between adjacent pole pieces.

[0020] A battery cell comprises a shell and the electrode assembly described in the above embodiment, wherein the electrode assembly is arranged in the shell.

[0021] A battery comprises a box and the battery monomer described in the above embodiment, wherein the battery monomer is arranged in the box.

[0022] In practical applications, the above-mentioned current collector, pole piece, electrode assembly, battery cell and battery can be infiltrated into the current collector by the electrolyte, and the intermediate insulating layer can be electrically isolated between the positive electrode active layer and the negative electrode active layer to avoid battery short circuit. Under the support of the electrolyte, some lithium ions released from the active layer on the metal layer can first enter the second microporous structure of a microporous layer through the first microporous structure on the metal layer, and then migrate to the intermediate insulating layer, and penetrate the intermediate insulating layer to enter the second microporous structure of another microporous layer, and finally reach and embed in another active layer covered with the "another metal layer" through the first microporous structure of another metal layer, so that some lithium ions can migrate between the positive electrode active layer and the negative electrode active layer through the current collector.

[0023] As a result, lithium ions are not only allowed to migrate through the outside of the current collector as in the traditional solution, but also allowed to migrate through the inside of the current collector, which is equivalent to adding a migration path for lithium ions between the positive electrode active layer and the negative electrode active layer. The lithium ions are more evenly distributed on the electrode sheet, which improves the electrochemical reaction efficiency of the battery and helps to improve battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0025] Figure 1This is a schematic diagram of the structure of the current collector of some embodiments of the present application.

[0026] Figure 2 This is a schematic diagram of the structure of the pole piece of some embodiments of the present application.

[0027] The reference numerals in the specific implementation manner are as follows:

[0028] 100, pole piece;

[0029] 10. Current collector; 11. Intermediate insulating layer; 12. Microporous layer; k1. Second microporous structure; 13. Metal layer; k2. First microporous structure; 13a. Positive metal layer; 13b. Negative metal layer;

[0030] 20. Positive electrode active layer; 30. Negative electrode active layer. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0032] In the description of the present application, it should be understood that terms such as “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships, if any, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0033] In addition, if present, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0034] In this application, unless otherwise clearly specified and limited, if any, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] In the present application, if it appears, unless otherwise clearly specified and limited, a first feature “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature “above”, “above” and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature “below”, “below” and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0036] It should be noted that, if present, when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0037] The current collector of traditional batteries is mostly made of metal foil such as copper foil and aluminum foil. The metal foil is dense, lacks porosity and cannot penetrate the electrolyte, so that both sides of the pole piece are mostly homogeneous active layers. During the battery cycle, the lithium ions between the pole pieces can only be transmitted on one side, and the transmission path is long, which is prone to uneven distribution of lithium ions and reduces battery performance. Based on this, the embodiment of the present application provides a current collector that can improve the above problems.

[0038] Please refer to Figure 1The current collector 10 provided in the embodiment of the present application includes an intermediate insulating layer 11, two microporous layers 12, and two metal layers 13. The intermediate insulating layer 11 is configured to be insulating and allow ions to pass through. The two microporous layers 12 are respectively arranged on opposite sides of the intermediate insulating layer 11. The two metal layers 13 are respectively covered on opposite sides of the two microporous layers 12, one of which is a positive electrode metal layer 13a, and the other metal layer 13 is a negative electrode metal layer 13b. Each metal layer 13 has a first microporous structure k2 connected to the outside, and each microporous layer 12 has a second microporous structure k1 connecting the intermediate insulating layer 11 and the first microporous structure k2.

[0039] That is, the current collector 10 is formed by stacking five layers, which are an intermediate insulating layer 11 located in the middle, two microporous layers 12 located on both sides of the intermediate insulating layer 11 , and two metal layers 13 located on both sides of the two microporous layers 12 in the stacking direction.

[0040] The intermediate insulating layer 11 has an insulating effect and can allow ions to pass through, and has a certain porosity. It can be, but is not limited to, selected from the diaphragm material used in the battery. It can be understood that the intermediate insulating layer 11 can be permeated with electrolyte to achieve ion penetration. It can be said that the thickness of the intermediate insulating layer 11 can be 10um-20um (for example, 15um). As the substrate structure of the current collector 10, when the value is within this range, the strength is more suitable and the electrical insulation is better.

[0041] The metal layer 13 is coated on the surface of the microporous layer 12, and is used to coat the active material thereon to form an active layer. The metal layer 13 has a first microporous structure k2, which is connected to the outside and allows electrolyte to penetrate and ions to pass through, that is, lithium ions released from the active material can pass through the first microporous structure k2. Of course, in some embodiments, the first microporous structure k2 can also be configured to allow electrolyte infiltration.

[0042] The microporous layer 12 has a second microporous structure k1, which can penetrate the electrolyte and can pass ions. In practical applications, lithium ions in the active material on the metal layer 13 can enter the second microporous structure k1 through the first microporous structure k2 in the metal layer 13, and migrate to the middle insulating layer 11 under the support of the electrolyte in the second microporous structure k1. The provision of the microporous layer 12 not only facilitates the covering of the metal layer 13, but also facilitates the smooth migration of lithium ions under the transportation of the electrolyte in the second microporous structure k1.

[0043] The positive electrode metal layer 13a is used to cover the positive electrode active material to form the positive electrode active layer 20. The negative electrode metal layer 13b is used to cover the negative electrode active material to form the negative electrode active layer 30. The positive electrode active material and the negative electrode active material are usually coated on the corresponding metal layer 13 by coating. Since the two metal layers 13 are used for different polarities, the current collector 10 can be made into a bipolar pole piece 100, and the presence of the intermediate insulating layer 11 can avoid short circuits between the positive and negative electrodes on both sides. Specifically, the positive electrode metal layer 13a can be an aluminum metal layer, and the negative electrode metal layer 13b can be a copper metal layer.

[0044] The current collector 10 is combined with Figure 2 , used to make a bipolar pole piece 100 with one positive pole and one negative pole. During the operation of the battery including the pole piece 100, the electrolyte can infiltrate into the current collector 10, and the intermediate insulating layer 11 can be electrically isolated between the positive electrode active layer 20 and the negative electrode active layer 30 to prevent the battery from short circuiting. Under the support of the electrolyte, some lithium ions released from the active layer on the metal layer 13 can first enter the second microporous structure k1 of a microporous layer 12 through the first microporous structure k1 on the metal layer 13, and then migrate to the intermediate insulating layer 11, and penetrate the intermediate insulating layer 11 to enter the second microporous structure k1 of another microporous layer 12, and finally reach and embed in another active layer covered with the "another metal layer 13" through the first microporous structure k1 of another metal layer 13, so that some lithium ions can migrate between the positive electrode active layer 20 and the negative electrode active layer 30 through the current collector 10.

[0045] It can be seen that in the technical solution of the present application, lithium ions are not only allowed to migrate through the outside of the current collector 10 as in the traditional solution, but also allowed to migrate through the inside of the current collector 10, which is equivalent to adding a migration path for lithium ions between the positive electrode active layer 20 and the negative electrode active layer 30. The lithium ions are more evenly distributed on the electrode 100, which improves the electrochemical reaction efficiency of the battery and helps to improve the battery performance.

[0046] In some embodiments, the metal layer 13 is sprayed on the microporous layer 12 and deposited to form the first microporous structure k2.

[0047] During the spraying process of the metal layer 13, metal particles are deposited on the microporous layer 12. During the deposition and stacking process of the metal particles, a first microporous structure k2 is formed between the metal particles. The first microporous structure k2 is usually an irregular three-dimensional grid structure. The first microporous structure k2 can form a first microporous structure k2 for ions to pass through.

[0048] At this time, the metal layer 13 is disposed on the microporous layer 12 by spraying, and the metal ions can obtain the first microporous structure k2 during the spraying deposition process. The arrangement of the metal layer 13 and the forming of the first microporous structure k2 are relatively simple.

[0049] Of course, in other embodiments, the metal layer 13 may also be obtained by setting a metal foil on the microporous layer 12 by gluing, and then forming a first microporous structure k2 on the metal foil by laser pore making, etching pore making, etc.

[0050] In some embodiments, the spraying thickness of the metal layer 13 is 1 μm-2 μm. Specifically, the spraying thickness of the metal layer 13 can be 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, and any value between adjacent values. When the spraying thickness of the metal layer 13 is within the above range, the first microporous structure k2 can be effectively formed inside the metal layer 13 by spraying deposition, so that the lithium ions in the active material coated on the metal layer 13 can migrate through the inside of the current collector 10 under the permission of the first microporous structure k2.

[0051] In some embodiments, the thickness of each microporous layer 12 is 2 μm-8 μm.

[0052] The thickness of the microporous layer 12 is the dimension in the stacking direction of the current collector 10. Specifically, the thickness of the microporous layer 12 can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, and any value between adjacent values. When the thickness of the microporous layer 12 is within the above range, it is helpful to control the overall thickness of the current collector 10.

[0053] In some embodiments, the pore size of the second microporous structure k1 is 3 μm-4 μm.

[0054] The second microporous structure k1 can be extended along the thickness direction of the current collector 10, or can be located in the microporous layer 12 in a three-dimensional network. Specifically, the pore size of the second microporous structure k1 can be selected as 3μm, 3.2μm, 3.5μm, 3.8μm, 4μm, or any value between adjacent values. When the pore size of the second microporous structure k1 is within the above range, it is not only easy to spray a thicker metal layer 13, but also the sprayed metal ions are not easy to embed into the second microporous structure k1. When the thickness of the metal layer 13 meets certain conductivity requirements, the microporous layer 12 can also have a good electrolyte penetration effect.

[0055] In some embodiments, the intermediate insulating layer 11 and the microporous layer 12 are both polymer layers. Specifically, the intermediate insulating layer 11 and the microporous layer 12 can be selected from polymer materials with insulating effects such as polyethylene, polypropylene, polyimide, and polyamide. In this way, the electrical insulation between the positive metal layer 13a and the negative metal layer 13b in the current collector 10 can be improved, the risk of short circuit of the pole piece 100 can be reduced, and the current collector 10 is lighter.

[0056] Specifically in the embodiment, the middle insulating layer 11 is a Kevlar film layer with nanopores. Kevlar film (Kevlar) is a well-known material, which has been proven to have good ability to allow lithium ions to pass through, and has good mechanical properties and is not easy to break, which can improve the reliability and safety of the pole piece 100.

[0057] Specifically in the embodiment, the microporous layer 12 is a polyimide layer. Polyimide has excellent insulation and mechanical properties, and can improve the reliability and safety of the pole piece 100.

[0058] In practical applications, the microporous layer 12 can be obtained by coating a polyimide material on the Kevlar film layer serving as the intermediate insulating layer 11 through a phase separation method.

[0059] In addition, refer to Figure 2 The present application also provides a pole piece 100, including the current collector 10, the positive electrode active layer 20 and the negative electrode active layer 30 in the above embodiment. The positive electrode active layer 20 is covered on the positive electrode metal layer 13a, and the negative electrode active layer 30 is covered on the negative electrode metal layer 13b. The active layers on both sides of the pole piece 100 have different polarities, and can be used as a bipolar pole piece 100.

[0060] The positive electrode active material in the positive electrode active layer 20 includes but is not limited to lithium cobalt oxide, lithium nickel oxide, nickel cobalt manganese ternary material, nickel cobalt aluminum oxide, lithium manganese oxide, lithium iron phosphate, lithium iron titanate, cobalt trifluoride, etc. The negative electrode active material in the negative electrode active layer 30 includes but is not limited to graphite, soft carbon, hard carbon, lithium titanate, metallic lithium, tin-based materials, silicon-based materials, etc.

[0061] In addition, the embodiment of the present application further provides an electrode assembly, including a diaphragm and the pole piece 100 of the above embodiment, wherein a diaphragm is arranged between adjacent pole pieces 100. The diaphragm is insulating and allows ions to pass through. For the selection of the diaphragm, please refer to the conventional settings. Among two adjacent pole pieces 100, the positive electrode active layer 20 of one pole piece 100 is separated from the negative electrode active layer 30 of the other pole piece 100 by a diaphragm. The electrode assembly can be a wound type or a laminated type.

[0062] In addition, the embodiment of the present application further provides a battery cell, including a housing and an electrode assembly in the above embodiment, wherein the electrode assembly is contained in the housing. In addition, an electrolyte is disposed in the housing. The housing may be provided with an injection hole for injecting electrolyte, and a pole, etc. may also be provided. The housing may be a hard shell structure or a soft package structure, and its specific form as an outer package is not limited. The specific structure of the battery cell may refer to the conventional setting.

[0063] In addition, the embodiment of the present application also provides a battery, including a box and the battery cell in the above embodiment, the battery cell is arranged in the box. A thermal management system for controlling the temperature of the battery cell, a battery management system for controlling the working parameters of the battery cell, etc. can be arranged in the box. The specific structure of the battery can refer to the conventional setting.

[0064] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0065] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A current collector, characterized in that: The current collector comprises: An intermediate insulating layer (11), the intermediate insulating layer (11) being configured to be insulating and allow ions to pass through; Two microporous layers (12) are respectively arranged on opposite sides of the middle insulating layer (11); and, Two metal layers (13) are respectively coated on opposite sides of the two microporous layers (12), one of the metal layers (13) is a positive electrode metal layer (13a), and the other metal layer (13) is a negative electrode metal layer (13b); Each of the metal layers (13) has a first microporous structure (k2) connected to the outside, and each of the microporous layers (12) has a second microporous structure (k1) connected to the intermediate insulating layer (11) and each of the first microporous structures (k2).

2. The current collector according to claim 1, characterized in that: The metal layer (13) is sprayed onto the microporous layer (12) and deposited to form the first microporous structure (k2).

3. The current collector according to claim 2, characterized in that: The spraying thickness of the metal layer (13) is 1 μm-2 μm.

4. The current collector according to any one of claims 1 to 3, characterized in that: The thickness of each microporous layer (12) is 2 μm-8 μm; and / or, The pore size of the second microporous structure (k1) is 3 μm-4 μm.

5. The current collector according to any one of claims 1 to 3, characterized in that: The intermediate insulating layer (11) and the microporous layer (12) are both high molecular polymer layers.

6. The current collector according to claim 5, characterized in that: The intermediate insulating layer (11) is a Kevlar film layer having nanopores; and / or the microporous layer (12) is a polyimide layer.

7. A pole piece, characterized in that: include: The current collector according to any one of claims 1 to 6; A positive electrode active layer (20) is coated on the positive electrode metal layer (13a); as well as The negative electrode active layer (30) is coated on the negative electrode metal layer (13b).

8. An electrode assembly, characterized in that: It comprises a diaphragm and the pole piece as claimed in claim 7, wherein the diaphragm is arranged between adjacent pole pieces.

9. A battery cell, characterized in that: It comprises a shell and the electrode assembly as claimed in claim 8, wherein the electrode assembly is arranged in the shell.

10. A battery, characterized in that: It comprises a box body and the battery cell as claimed in claim 9, wherein the battery cell is arranged in the box body.

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