Composite current collector and battery comprising same

Abstract

The utility model relates to the technical field of batteries, and provides a composite current collector and a battery comprising the same, and the composite current collector comprises a base material layer and a conductive layer. Wherein a plurality of arc-shaped grooves are formed in the surface of at least one side of the base material layer at intervals; the conductive layer is at least arranged on the surface of one side of the base material layer with the arc-shaped groove. The arc-shaped grooves are formed in the surface of the base material layer, so that more contact points and larger contact area can be formed between the base material layer and the conductive layer, the interlocking capacity between the base material layer and the conductive layer is improved, electrolyte is prevented from corroding the connecting position of the base material layer and the conductive layer, and the binding force is higher. And secondly, when the composite current collector is subjected to a pulling force, the arc-shaped grooves can disperse stress, reduce deformation caused by the pulling force, improve the tensile strength of the composite current collector and avoid the problem that the composite current collector is shrunk after being coated with the active material, so that the active material falls off.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a composite current collector and a battery including the same. Background Technology

[0002] Composite current collectors mainly adopt a sandwich structure of "metal-polymer material-metal", with polymer materials such as PET / PP / PI as the middle layer, and aluminum or copper metal deposited on the upper and lower layers to form a metal conductive layer.

[0003] Polypropylene's non-polar material properties make it difficult to form coatings with high adhesion. To address the weak adhesion of subsequent coatings on polypropylene films, traditional technologies employ two methods. First, polar substances are introduced into the polypropylene base film raw material, such as blending with other polar particles. However, due to the ultra-thin nature of the composite current collector substrate, film formation is difficult in actual film-stretching production. Another approach is to coat the polypropylene film with a highly polar solution, such as acrylic acid or acrylate solutions, during the coating process to improve the adhesion between the substrate and the coating. However, this solution-coating method carries the risk of corrosion from the organic electrolytes in lithium-ion batteries. Therefore, improving the adhesion between the polymer material and the metal layer in the composite current collector has become a pressing technical problem that needs to be solved. Utility Model Content

[0004] Based on this, this application provides a composite current collector that is easy to implement and has a strong bond between the substrate layer and the conductive layer, as well as a battery including the same.

[0005] In a first aspect, this application provides a composite current collector, the composite current collector comprising:

[0006] A substrate layer, wherein at least one surface of the substrate layer is provided with a plurality of spaced arc-shaped grooves;

[0007] A conductive layer is disposed at least on one side surface of the substrate layer having the arcuate groove.

[0008] In some embodiments, the width of the arcuate groove gradually decreases from the center to the end.

[0009] In some embodiments, the arc-shaped groove is symmetrically arranged with the perpendicular bisector of the line connecting the two ends of the arc-shaped groove as the axis of symmetry.

[0010] In some embodiments, the center width of the arcuate groove is 5nm to 50nm.

[0011] In some embodiments, the end width of the arcuate groove is less than or equal to 1 nm.

[0012] In some embodiments, the connecting lines at both ends of the plurality of arcuate grooves are in the same direction.

[0013] In some embodiments, adjacent arcuate grooves have opposite opening directions in a direction perpendicular to the line connecting the two ends of the arcuate groove.

[0014] In some embodiments, the spacing L between two adjacent arcuate grooves in any direction satisfies: 0 < L < 200 μm.

[0015] In some embodiments, the number of arcuate grooves per unit length in any direction on the surface of the substrate layer is greater than 4 per mm.

[0016] In some embodiments, the radius of the arcuate groove is 0.5 rad to 3.5 rad.

[0017] In some embodiments, the straight-line distance between the two ends of the arcuate groove is 5 μm to 100 μm.

[0018] In some embodiments, the conductive layer includes a transition layer and a metal layer sequentially stacked along the surface of the substrate layer away from it.

[0019] In some embodiments, the thickness of the transition layer is 10 nm to 100 nm.

[0020] In some embodiments, the thickness of the metal layer is 0.5 μm to 2 μm.

[0021] In some embodiments, the ratio between the depth of the arcuate groove and the thickness of the transition layer is 1:(2~3).

[0022] In a second aspect, this application provides a battery comprising a positive electrode, a separator, and a negative electrode stacked together, wherein the current collector in the positive electrode and / or the current collector in the negative electrode are selected from the composite current collectors described in the first aspect.

[0023] Compared with traditional technologies, this application has at least the following beneficial effects:

[0024] This application, by setting arc-shaped grooves on the surface of the substrate layer, can form more contact points and a larger contact area between the substrate layer and the conductive layer, thereby improving the interlocking ability between the substrate layer and the conductive layer, preventing electrolyte corrosion at the junction of the substrate layer and the conductive layer, and resulting in stronger adhesion. Secondly, when the composite current collector is subjected to tensile force, the arc-shaped grooves can disperse stress, reduce deformation under tensile force, improve the tensile strength of the composite current collector, and avoid the problem of shrinkage and detachment of the active material after coating the composite current collector. Attached Figure Description

[0025] Figure 1 This is a cross-sectional schematic diagram of a composite current collector provided in one embodiment of this application.

[0026] Figure 2 This is a schematic diagram of the surface structure of a composite current collector with an arc-shaped groove on one side of the substrate layer, provided in one embodiment of this application. MD refers to the direction of the connecting line between the two ends of the arc-shaped groove, and TD refers to the direction perpendicular to the connecting line between the two ends of the arc-shaped groove.

[0027] Among them, 10-substrate layer; 11-arc groove; 20-conductive layer; 21-transition layer; 22-metal layer. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the accompanying drawings, embodiments, and examples. These embodiments and examples are for illustrative purposes only and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to enable a more thorough and comprehensive understanding of the disclosure of the present application. It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. Furthermore, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0029] It should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] In the description of this application, unless otherwise expressly specified and limited, the terms "connected," "linked," "fixed," and "set" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the meaning of the above terms in this application according to the specific circumstances.

[0031] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0032] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0033] In this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0034] All references to this application are incorporated herein by reference as if each document were individually incorporated herein by reference. Unless they conflict with the purpose and / or technical solution of this application, all cited references are incorporated herein by reference in their entirety and for all purposes. When references are cited in this application, the definitions of relevant technical features, terms, nouns, phrases, etc., are also incorporated herein by reference. Examples and preferred embodiments of the cited technical features may also be incorporated herein by reference, but only to the extent that they enable the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or modifications shall be made adaptably to the description in this application.

[0035] In traditional technologies, the bonding force between the polymer material layer and the conductive metal layer in composite current collectors is weak. Modification of the polymer material layer, such as introducing polar substances, can improve the bonding force. However, the introduction of polar substances results in poor film-forming properties of the polymer material layer, making it difficult to form ultra-thin polymer material layers. Alternatively, a polar solution, such as acrylic acid or acrylate solutions, can be coated onto the surface of the polymer material layer to improve the bonding force between the substrate and the coating. However, coating with polar solutions makes the current collector susceptible to electrolyte corrosion during use, thus affecting battery performance.

[0036] Based on this, the first aspect of this application provides a composite current collector, such as... Figure 1 and Figure 2 As shown, the composite current collector includes a substrate layer 10 and a conductive layer 20.

[0037] The substrate layer 10 has a plurality of spaced arc-shaped grooves 11 on at least one side surface. The conductive layer 20 is disposed at least on the side surface of the substrate layer 10 having the arc-shaped grooves 11.

[0038] This application, by providing an arc-shaped groove 11 on the surface of the substrate layer 10, can form more contact points and a larger contact area between the substrate layer 10 and the conductive layer 20, thereby improving the interlocking ability between the substrate layer 10 and the conductive layer 20, preventing electrolyte corrosion at the connection between the substrate layer 10 and the conductive layer 20, and resulting in stronger adhesion. Secondly, when the composite current collector is subjected to tensile force, the arc-shaped groove 11 can disperse stress, reduce deformation under tensile force, improve the tensile strength of the composite current collector, and prevent the problem of shrinkage leading to the shedding of the active material after coating the composite current collector.

[0039] It is understandable that the arc-shaped groove 11 refers to a groove whose relative edges along the opening direction are all arc-shaped, that is, when the arc-shaped groove 11 is opened, it is opened in an arc-shaped direction. For example, the arc-shaped groove 11 can be C-shaped.

[0040] It should be noted that the arc-shaped groove on the surface of the substrate layer in this application can be formed by mechanical processing, chemical etching and laser processing, or the arc-shaped groove structure can be formed directly on the surface of the substrate layer during preparation.

[0041] In some embodiments, the width of the arc-shaped groove 11 gradually decreases from the center to the end. The arc-shaped groove 11 provided in this application, as described above, can improve the interlocking effect between the substrate layer 10 and the conductive layer 20 located at the end of the arc-shaped groove 11, further enhancing the bonding force between the conductive layer 20 and the substrate layer 10.

[0042] In some embodiments, the arc-shaped groove 11 is symmetrically arranged with the perpendicular bisector of the line connecting the two ends of the arc-shaped groove 11 as the axis of symmetry. The symmetrical arc-shaped groove 11 provided in this application ensures uniform force distribution at the arc-shaped groove 11 and avoids heat accumulation during use, which could affect battery performance.

[0043] Alternatively, the arc-shaped groove 11 can be crescent-shaped.

[0044] In some embodiments, the center width of the arc-shaped groove 11 is 5nm to 50nm, for example, it can be 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, or 50nm. The center width of the arc-shaped groove 11 set as described above in this application ensures the bonding effect between the substrate layer 10 and the conductive layer 20. If the width is relatively large, it may lead to poor bonding between the substrate layer 10 and the conductive layer 20, affecting the adhesion. If the width is relatively small, the conductive layer 20 may not be able to enter the arc-shaped groove 11 during the fabrication process, resulting in a decrease in adhesion.

[0045] In some embodiments, the end width of the arcuate groove 11 is less than or equal to 1 nm.

[0046] In some embodiments, the connecting lines at both ends of the plurality of arc-shaped grooves 11 are in the same direction. By aligning the arc-shaped grooves 11 as described above, applying tension to the composite current collector in the direction of the connecting lines at both ends of the arc-shaped grooves 11 can effectively prevent deformation of the current collector. For example, when coating the composite current collector with active material, the composite current collector will bear a large tensile force in the mechanical conveying direction. By aligning the connecting lines at the ends of the arc-shaped grooves 11 with the mechanical conveying direction, the deformation of the composite current collector during coating can be reduced, thereby effectively avoiding the problem of active material detachment caused by shrinkage of the composite current collector after coating.

[0047] In some embodiments, adjacent arcuate grooves 11 have opposite opening directions in a direction perpendicular to the line connecting the two ends of the arcuate groove 11. Optionally, two adjacent arcuate grooves 11 are symmetrically arranged. It is understood that the opening direction of the arcuate groove 11 refers to the side of the arcuate concavity.

[0048] The arrangement of the arc-shaped grooves 11 in this application ensures the uniformity of stress and heat conduction in the substrate layer 10, and prevents the composite current collector from deforming and accumulating heat under external force.

[0049] In some embodiments, the spacing L between two adjacent arcuate grooves in any direction satisfies: 0 < L < 200 μm, for example, it can be 1 μm, 5 μm, 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm or 190 μm.

[0050] It is understandable that the spacing distance refers to the distance between the closest edge points of two adjacent arcuate grooves in a certain direction.

[0051] In some embodiments, the number of arc grooves per unit length in any direction on the surface of the substrate layer is greater than 4 per mm. The number of arc grooves per unit length refers to the number of arc grooves intersecting a line segment in a given direction, where the ratio of the number of arc grooves to the length of the line segment is the number of arc grooves per unit length.

[0052] This application selects the spacing between two adjacent arc-shaped grooves 11 in any direction and the number of arc-shaped grooves per unit length as described above to ensure the number of arc-shaped grooves 11 per unit area of ​​the substrate layer 10, thereby improving the interlocking capability between the substrate layer 10 and the conductive layer 20 and achieving a tight bond between them. If the spacing is relatively large, resulting in fewer arc-shaped grooves 11 on the substrate layer 10 (i.e., the arc-shaped grooves 11 are sparsely distributed), the interlocking effect between the substrate layer 10 and the conductive layer 20 will be affected, and the bonding force may be reduced.

[0053] In some embodiments, two adjacent arcuate grooves 11 can be arranged side by side or staggered.

[0054] In some embodiments, the arcuate groove 11 has an arcuate radius of 0.5 rad to 3.5 rad, for example, it can be 0.5 rad, 1.0 rad, 1.5 rad, 2.0 rad, 2.5 rad, 3.0 rad or 3.5 rad.

[0055] In some embodiments, the straight-line distance between the two ends of the arcuate groove 11 is 5μm to 100μm, for example, it can be 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm.

[0056] The distance and curvature between the two ends of the arc-shaped groove 11 selected in this application, as described above, have good resistance to deformation and can improve the bonding force between the substrate layer 10 and the conductive layer 20. This effectively avoids material waste caused by a relatively large curvature and problems such as unevenness on the surface of the composite current collector.

[0057] In some embodiments, such as Figure 1 As shown, the conductive layer 20 includes a transition layer 21 and a metal layer 22 that are sequentially stacked along the surface away from the substrate layer 10.

[0058] In some embodiments, the thickness of the transition layer 21 is 10nm to 100nm, for example, it can be 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm or 100nm.

[0059] In some embodiments, the thickness of the metal layer 22 is 0.5μm to 2μm, for example, it can be 0.5μm, 0.6μm, 0.8μm, 1.0μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm or 2.0μm.

[0060] In some embodiments, the thickness of the substrate layer 10 is 2μm to 6μm, for example, it can be 2.5μm, 3.0μm, 3.5μm, 4.0μm, 4.5μm, 5.0μm, 5.5μm or 6.0μm.

[0061] In some embodiments, the ratio between the depth of the arcuate groove 11 and the thickness of the transition layer 21 is 1:(2~3), for example, it can be 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3.0.

[0062] In some embodiments, the material of the substrate layer 10 may be selected appropriately according to the needs of use, for example, it may be a polypropylene layer.

[0063] In some embodiments, the material of the transition layer 21 can be reasonably selected according to the needs of use, such as nickel, chromium or nickel-chromium alloy.

[0064] In some embodiments, the material of the metal layer 22 may be selected appropriately according to the needs of use, for example, it may be copper or aluminum.

[0065] In some embodiments, the transition layer 21 and the metal layer 22 in this application can be formed by deposition. For example, the transition layer 21 and the metal layer 22 can be formed by magnetron sputtering, respectively. Alternatively, the metal layer 22 can be thickened by electroplating.

[0066] This application selects the ratio between the depth of the arc-shaped groove 11 and the thickness of the transition layer 21 as described above. This ensures that the transition layer 21 can cover the arc-shaped groove 11, resulting in strong interlocking between the transition layer 21 and the substrate layer 10. This improves the bonding strength between the transition layer 21 and the substrate layer 10, and also enhances the corrosion resistance at the connection point. If the ratio is relatively large, i.e., the arc-shaped groove 11 is deep, the transition layer 21 may not completely cover the substrate layer 10, leading to light transmission and increasing the possibility of electrolyte corrosion, thus affecting battery performance. If the ratio is relatively small, i.e., the arc-shaped groove 11 is shallow, the interlocking strength between the transition layer 21 and the substrate layer 10 may be weak, affecting the bonding strength.

[0067] A second aspect of this application provides a battery comprising a positive electrode, a separator, and a negative electrode stacked together, wherein the current collector in the positive electrode and / or the current collector in the negative electrode are selected from the composite current collectors described in the first aspect.

[0068] In some embodiments, when the composite current collector is disposed in the negative electrode sheet, the material of the metal layer 22 may be copper.

[0069] In some embodiments, when the composite current collector is disposed in the positive electrode, the material of the metal layer 22 may be aluminum.

[0070] In summary, by providing an arc-shaped groove 11 on the surface of the substrate layer 10, this application can form more contact points and a larger contact area between the substrate layer 10 and the conductive layer 20, thereby improving the interlocking ability between the substrate layer 10 and the conductive layer 20, preventing electrolyte corrosion at the connection between the substrate layer 10 and the conductive layer 20, and resulting in stronger adhesion. Secondly, when the composite current collector is subjected to tensile force, the arc-shaped groove 11 can disperse stress, reduce deformation under tensile force, improve the tensile strength of the composite current collector, and prevent the problem of shrinkage leading to the shedding of the active material after coating the composite current collector.

[0071] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0072] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A composite current collector, characterized by, The composite current collector comprises: a substrate layer (10) having a plurality of arc-shaped grooves (11) arranged at intervals on at least one side surface of the substrate layer (10); a conductive layer (20) arranged on at least one side surface of the substrate layer (10) having the arc-shaped grooves (11).

2. The composite current collector of claim 1, wherein The width of the arc-shaped grooves (11) gradually decreases from the center to the end.

3. The composite current collector of claim 1, wherein The arc-shaped grooves (11) are symmetrically arranged with the center line of the two end connecting lines of the arc-shaped grooves (11) as the axis of symmetry.

4. The composite current collector of claim 1, wherein The central width of the arc-shaped grooves (11) is 5 nm to 50 nm; and / or, The end width of the arc-shaped grooves (11) is less than or equal to 1 nm.

5. The composite current collector of claim 1, wherein The connecting lines of the two ends of the plurality of arc-shaped grooves (11) are in the same direction.

6. The composite current collector of claim 1, wherein In the direction perpendicular to the connecting line of the two ends of the arc-shaped grooves (11), the opening directions of adjacent arc-shaped grooves (11) are opposite.

7. The composite current collector of claim 1, wherein The spacing distance L between any two adjacent arc-shaped grooves (11) in any direction satisfies: 0 < L < 200 μm; and / or, The number of arc-shaped grooves per unit length in any direction on the surface of the substrate layer is greater than 4 / mm; The curvature of the arc-shaped grooves (11) is 0.5 rad to 3.5 rad; and / or, The straight line distance between the two ends of the arc-shaped grooves (11) is 5 μm to 100 μm.

8. The composite current collector of claim 1, wherein The conductive layer (20) comprises a transition layer (21) and a metal layer (22) arranged in sequence away from the surface of the substrate layer (10).

9. The composite current collector of claim 8, wherein, The thickness of the transition layer (21) is 10 nm to 100 nm; and / or, The thickness of the metal layer (22) is 0.5 μm to 2 μm; and / or, The ratio between the depth of the arc-shaped grooves (11) and the thickness of the transition layer (21) is 1:2 to 1:

3.

10. A battery, characterized by The battery comprises a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence, and the current collector in the positive electrode sheet and / or the current collector in the negative electrode sheet is selected from the composite current collector according to any one of claims 1-9.

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