High-peel-strength composite metal foil, metal-clad laminated plate and battery

Abstract

The invention relates to a composite metal foil with high peel strength, a metal-clad laminated plate and a battery. The high-peel-strength composite metal foil comprises a base film layer and a metal layer, the metal layer is arranged on at least one side face of the base film layer, a plurality of protrusions are arranged on the side face, close to the base film layer, of the metal layer, the height of the protrusions is 0.5-5 micrometers, the protrusions comprise the first protrusions and the second protrusions, the height of the first protrusions is 1.5-5 micrometers, the height of the second protrusions is 1.5-5 micrometers, and the height of the second protrusions is 1.5-5 micrometers. The height of the second protrusions ranges from 0.5 micrometer to 1.5 micrometers. Wherein the second protrusions are arranged between at least 40% of the adjacent first protrusions. The overall design is beneficial to improving the interlayer binding force between the metal layer and the base film layer, the delamination resistance of the composite metal foil can be improved, the working safety of the lithium battery can be improved, meanwhile, the bonding stability of a circuit and the metal foil can be improved when the composite metal foil is used for circuit manufacturing, and the circuit manufacturing quality can be improved.

Description

Technical Field

[0001] This invention relates to the field of metal materials technology, and in particular to a high peel strength composite metal foil, a metal-clad laminate, and a battery. Background Technology

[0002] As an emerging and comprehensive economic form, the low-altitude economy has seen rapid development across its entire industrial chain globally in recent years. Among these developments, electric vertical takeoff and landing (eVTOL) aircraft have demonstrated remarkable momentum. The rapid development of new energy vehicles, in turn, places higher demands on the safety, stability, lightweight design, and energy density of battery systems.

[0003] Existing technologies employ sandwich-structured composite metal foils to replace traditional pure metal foils. These foils are formed through magnetron sputtering and water plating, allowing for controllable thickness to meet internal resistance requirements. However, the interlayer bonding strength of these composite metal foils is too low, leading to delamination during use and causing battery failure. Furthermore, with the miniaturization and increasing multifunctionality of electronic products, the peel strength requirements for metal foil materials in circuit board manufacturing are becoming increasingly stringent. Existing composite metal foils are prone to detachment during circuit fabrication, affecting the quality of the circuitry. Summary of the Invention

[0004] Therefore, it is necessary to provide a high peel strength composite metal foil, a metal-clad laminate and a battery, which can effectively improve the interlayer bonding force of the composite metal foil, improve the working safety of lithium batteries, and also help improve the quality of circuit manufacturing when used in circuit fabrication.

[0005] The technical solution is as follows: A high peel strength composite metal foil includes a base film layer and a metal layer. The base film layer has the metal layer disposed on at least one side. The metal layer has a plurality of protrusions on one side near the base film layer. The height of the protrusions is 0.5-5 μm. The protrusions include a first protrusion and a second protrusion. The height of the first protrusion is 1.5-5 μm, and the height of the second protrusion is 0.5-1.5 μm. The second protrusion is disposed between at least 40% of adjacent first protrusions.

[0006] In one embodiment, the distance between adjacent first protrusions is 10-100 μm.

[0007] In one embodiment, the proportion of the first protrusion is more than 60%, and the average height of the first protrusion is 1.5-2.5 μm.

[0008] In one embodiment, the number of second protrusions between adjacent first protrusions is greater than or equal to 3.

[0009] In one embodiment, the shape of the first protrusion includes an inverted triangle; wherein, along the thickness direction, the width of the first protrusion gradually decreases from one end face near the metal layer to the other end.

[0010] In one embodiment, the second protrusion is positioned at its maximum width away from the metal layer relative to the interface between the second protrusion and the metal layer.

[0011] In one embodiment, the maximum width of the second protrusion is distributed between 1 / 4H and 3 / 4H of the height H of the second protrusion.

[0012] In one embodiment, the roughness Sdr of the side of the metal layer near the base film layer is 30%-500%.

[0013] In one embodiment, an adjustment layer is provided between the metal layer and the base film layer.

[0014] In one embodiment, the conditioning layer comprises any one or a combination of two or more of a coupling agent, an organic polymer, or an alloy.

[0015] A metal-clad laminate comprising the high peel strength composite metal foil described in any one of the above descriptions.

[0016] A battery comprising the high peel strength composite metal foil described in any one of the above descriptions.

[0017] The beneficial effects of the above technical solution are as follows:

[0018] The aforementioned high peel strength composite metal foil utilizes a multi-level mechanical interlocking structure formed by setting a first protrusion and a second protrusion with a specific height range on the side of the metal layer near the base film layer. The first protrusion provides the main interlocking support, while the second protrusion fills the gaps between adjacent first protrusions. The design, with at least 40% of adjacent first protrusions having a second protrusion, ensures the continuity and density of the interlocking structure, enhancing the physical bonding between the metal layer and the base film layer. This design helps balance the interlocking effect and the structural strength of the metal layer. The 1.5-5μm height range of the first protrusion ensures sufficient interlocking depth, while the 0.5-1.5μm height range of the second protrusion precisely fills the gaps without affecting the overall bonding flatness. The at least 40% distribution of the second protrusion ensures full coverage of the interlocking structure. The overall design improves the interlayer bonding force between the metal layer and the base film layer, enhancing the composite metal foil's resistance to delamination and thus improving the operational safety of lithium batteries. Furthermore, when used in circuit fabrication, it improves the bonding stability between the circuit and the metal foil, contributing to higher circuit fabrication quality.

[0019] The aforementioned metal-clad laminate uses the high peel strength composite metal foil. By leveraging the excellent interlayer bonding performance of the composite metal foil, the bonding stability between the layers of the laminate is improved, avoiding interlayer separation problems during processing or use. This is beneficial to improving the structural stability of the metal-clad laminate, thereby enhancing its peel resistance and ultimately improving the processing quality and reliability of the laminate in applications such as circuit fabrication.

[0020] The aforementioned battery uses the high peel strength composite metal foil, which utilizes the good interlayer bonding force and structural stability of the composite metal foil to avoid delamination failure of the internal metal foil components of the battery, ensuring the continuity and structural integrity of the internal circuit of the battery, and reducing battery safety hazards caused by metal foil failure. This helps to improve the battery's operational safety, enhance the battery's structural stability and service life, and also helps to improve the battery's energy density stability, thus ensuring the overall performance of the battery. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the high peel strength composite metal foil described in one embodiment.

[0024] Figure 2 This is another structural schematic diagram of the high peel strength composite metal foil described in one embodiment.

[0025] Explanation of reference numerals in the attached figures:

[0026] 100. High peel strength composite metal foil; 110. Base film layer; 120. Metal layer; 121. First protrusion; 122. Second protrusion; 130. Adjustment layer. Detailed Implementation

[0027] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention 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 invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0032] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0033] See Figure 1 Figure 1 shows a schematic diagram of the structure of a high peel strength composite metal foil 100 according to an embodiment of the present invention. The high peel strength composite metal foil 100 provided in this embodiment includes a base film layer 110 and a metal layer 120. The metal layer 120 is disposed on at least one side of the base film layer 110. The side of the metal layer 120 near the base film layer 110 has a plurality of protrusions, the height of which is 0.5-5 μm. The protrusions include first protrusions 121 and second protrusions 122. The height of the first protrusion 121 is 1.5-5 μm, and the height of the second protrusion 122 is 0.5-1.5 μm. At least 40% of adjacent first protrusions 121 are connected by a second protrusion 122.

[0034] The aforementioned high peel strength composite metal foil 100 utilizes a multi-level mechanical interlocking structure formed by providing a first protrusion 121 and a second protrusion 122 of a specific height range on the side of the metal layer 120 near the base film layer 110. The first protrusion 121 provides the main interlocking support, and the second protrusion 122 fills the gap between adjacent first protrusions 121. At the same time, the design of providing the second protrusion 122 between at least 40% of the adjacent first protrusions 121 ensures the continuity and compactness of the interlocking structure, thereby enhancing the physical bonding between the metal layer 120 and the base film layer 110.

[0035] Furthermore, the aforementioned height range of the protrusions helps to balance the occlusal effect and the structural strength of the metal layer 120. The first protrusion 121, with a height range of 1.5-5μm, can ensure sufficient occlusal depth. The second protrusion 122, with a height range of 0.5-1.5μm, can accurately fill the gap without affecting the overall flatness of the joint. The distribution ratio of at least 40% of the second protrusion 122 helps to ensure the full coverage of the occlusal structure. If the height of the first protrusion 121 is less than 1.5μm, it is difficult to form effective occlusal support. If it is greater than 5μm, it is easy to cause stress concentration in the metal layer 120 and make it prone to breakage. If the height of the second protrusion 122 is less than 0.5μm, it cannot effectively fill the gap; if it is greater than 1.5μm, it may interfere with the first protrusion 121 and destroy the interlocking structure. If the distribution ratio of the second protrusion 122 is less than 40%, the interlocking structure will be discontinuous, reducing the interlayer bonding stability. The overall design is conducive to improving the interlayer bonding force between the metal layer 120 and the base film layer 110, which can improve the anti-delamination ability of the composite metal foil 100, thereby improving the working safety of the lithium battery. At the same time, when used for circuit fabrication, it can improve the bonding stability between the circuit and the metal foil, which is conducive to improving the quality of circuit fabrication.

[0036] Furthermore, metal layers 120 are provided on both opposite sides of the base film layer 110.

[0037] It should be noted that the metal layer 120 can be made of copper, aluminum, gold, silver, nickel, zinc, chromium, magnesium, iron, tin or other materials, or an alloy of two or more elements.

[0038] The base film layer 110 can be made of PET, PVC, epoxy resin, PI, PTFE, EVA or other non-metallic materials.

[0039] For example, when the metal layer 120 is copper foil and the substrate layer is PET, the composite metal foil 100 is a negative electrode current collector material used in the negative electrode of a lithium battery. When the metal layer 120 is aluminum foil, the composite metal foil 100 is a positive electrode current collector material used in the positive electrode of a lithium battery. When the metal layer 120 is copper foil and the base film layer 110 is PI, the composite metal foil 100 is a flexible copper-clad laminate used for fabricating circuits.

[0040] Optionally, the height of the first protrusion 121 can be 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 μm or any value within the range or any range of values, and the height of the second protrusion 122 can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 μm or any value within the range or any range of values.

[0041] In one embodiment, the distance between adjacent first protrusions 121 is 10-100 μm. This distance range allows the first protrusions 121 to form uniformly distributed support points on the surface of the metal layer 120, which avoids local stress concentration in the metal layer 120 due to excessively small spacing, and also prevents the interlocking support effect from weakening due to excessively large spacing, thus ensuring the uniformity and effectiveness of the mechanical interlocking structure.

[0042] Specifically, the aforementioned distance range is beneficial for improving the uniformity of the bonding between the metal layer 120 and the base film layer 110, allowing each first protrusion 121 to fully exert its supporting function while avoiding mutual interference between adjacent protrusions. If the spacing is less than 10 μm, the local protrusions of the metal layer 120 will be too dense, resulting in greater stress concentration and making the metal layer 120 prone to cracking. If the spacing is greater than 100 μm, the protrusion distribution will be too sparse, resulting in insufficient interlocking support points and an inability to form a stable overall interlocking structure, significantly reducing the interlayer bonding force. This design can improve the overall structural stability of the composite metal foil 100, avoid delamination problems caused by weak local bonding, and thus improve the reliability of the composite metal foil 100 in use.

[0043] Furthermore, the distance between adjacent first protrusions 121 is obtained by measurement under SEM slices.

[0044] In one embodiment, the proportion of the first protrusion 121 is more than 60%, and the average height of the first protrusion 121 is 1.5-2.5μm.

[0045] By limiting the proportion of the first protrusion 121 to more than 60% and specifying its average height to 1.5-2.5μm, the first protrusion 121 can be ensured to play a dominant role as the main occlusal structure. At the same time, the appropriate average height can balance the occlusal depth and the structural strength of the metal layer 120, avoiding the metal layer 120 from being too high and easily breaking, or the occlusal effect from being too low.

[0046] Furthermore, the fact that the first protrusion 121 accounts for more than 60% helps to ensure the dominant position of the main interlocking structure and ensure the core support force of the interlayer bonding; the average height range of 1.5-2.5μm can accurately balance the interlocking depth and the structural strength of the metal layer 120, ensuring sufficient interlocking depth to improve bonding force while maintaining the integrity and toughness of the metal layer 120; if the proportion of the first protrusion 121 is less than 60%, the proportion of the second protrusion 122 will be too high, failing to provide sufficient core support force, resulting in insufficient interlayer bonding force; if the average height is less than 1.5μm, the interlocking depth is insufficient and the bonding force is weak; if it is greater than 2.5μm, the local thickness of the metal layer 120 will be uneven, stress concentration will be obvious, and it will be prone to breakage; this design helps to improve the core bonding ability between the metal layer 120 and the base film layer 110, improves the peel strength stability of the composite metal foil 100, and also helps to improve the structural integrity of the metal layer 120, ensuring the adaptability of the composite metal foil 100 in subsequent processing.

[0047] In one embodiment, the number of second protrusions 122 between adjacent first protrusions 121 is greater than or equal to three. This further fills the gaps between the first protrusions 121, forming a denser multi-level interlocking structure, enhancing the physical bonding between the metal layer 120 and the base film layer 110, reducing voids at the bonding interface, and improving the density of the interface bonding. Beneficial effects: It helps improve the density of the bonding between the metal layer 120 and the base film layer 110, enhances the peel resistance of the composite metal foil 100, further reduces the risk of delamination during use, and helps improve the bonding stability during circuit fabrication.

[0048] In one embodiment, the first protrusion 121 has an inverted triangular shape; wherein, along the thickness direction, the width of the first protrusion 121 gradually decreases from one end face near the metal layer 120 to the other end. This structure allows the first protrusion 121 to form an interlocking effect when bonded to the base film layer 110. The tip of the inverted triangle easily embeds into the base film layer 110, while the two sides can effectively adhere to the base film layer 110, increasing the resistance during peeling. This improves the bonding strength between the metal layer 120 and the base film layer 110, enhances the anti-delamination capability of the composite metal foil 100, and thus improves the structural stability and reliability of the circuit fabrication during battery use.

[0049] In one embodiment, the position where the second protrusion 122 has its maximum width is located away from the metal layer 120 relative to the interface between the second protrusion 122 and the metal layer 120. That is, the position where the second protrusion 122 has its maximum width is not at the interface with the metal layer 120; along the thickness direction of the composite metal foil 100, starting from the interface, at least a portion of the width of the second protrusion 122 increases. This structural arrangement allows the second protrusion 122 to form a wider interlocking surface on the side near the base film layer 110, forming a physical hook, while combining with chemical bonding, which helps to enhance the physical interlocking force with the base film layer 110, while avoiding stress concentration at the root of the protrusion caused by the maximum width being close to the metal layer 120, thus improving the structural stability of the second protrusion 122, thereby improving the bonding effect between the second protrusion 122 and the base film layer 110. In addition, it can also improve the overall peel strength of the composite metal foil 100, further ensuring the stability of the interlayer bonding and extending the service life of the composite metal foil 100.

[0050] Furthermore, the maximum width of the second protrusion 122 is distributed between 1 / 4H and 3 / 4H of the height H of the second protrusion 122. This range ensures that the maximum width position is within the effective force-bearing area of ​​the second protrusion 122, which not only ensures sufficient engagement depth but also avoids easy breakage of the protrusion due to excessive deviation of the maximum width position, thus ensuring the stable performance of the interlocking function of the second protrusion 122.

[0051] Specifically, the aforementioned maximum width range helps improve the stress rationality of the second protrusion 122, ensuring that the maximum engagement width is within the effective stress range, thus improving engagement stability and durability. If the maximum width is below 1 / 4H (near the metal layer 120), the engagement depth is insufficient, the engagement effect is poor, and stress concentration at the root of the protrusion is likely to occur. If it is above 3 / 4H (near the top of the base film layer 110), the top of the protrusion is too wide, making it difficult to embed into the base film layer 110, and the protrusion is prone to breakage due to excessive stress at the top. This design can improve the engagement stability of the second protrusion 122, thereby improving the durability of the bond between the metal layer 120 and the base film layer 110 and reducing delamination problems caused by protrusion structure failure.

[0052] In one embodiment, the roughness Sdr of the side of the metal layer 120 near the base film layer 110 is 30%-500%. It should be noted that roughness Sdr is the ratio of the area of ​​the interface expansion, where the expanded area (surface area) of the defined region represents how much the area has increased relative to the defined region. For example, the Sdr of a completely flat surface is 0.

[0053] Specifically, a suitable roughness Sdr can increase the contact area between the metal layer 120 and the base film layer 110. Simultaneously, the rough surface can form more tiny mechanical interlocking points, enhancing the physical adsorption and friction between the interfaces. Furthermore, a roughness Sdr range of 30%-500% is beneficial for improving the interfacial bonding force between the metal layer 120 and the base film layer 110. This not only improves the bonding effect by increasing the contact area and tiny interlocking points but also avoids the adhesion of the metal layer 120 and the base film layer 110 due to abnormal roughness. If the roughness Sdr is below 30%, the increase in contact area is limited, the number of tiny interlocking points is insufficient, and the improvement in interfacial bonding force is not significant. If it is above 500%, the surface of the metal layer 120 is too rough, which can easily lead to gaps during the bonding of the base film layer 110 and may scratch the base film layer 110, thus reducing the bonding stability. This design can improve the peel strength of the composite metal foil 100 and also improve the bonding effect with other materials in subsequent processing, enhancing the compatibility of the composite metal foil 100.

[0054] In one embodiment, see Figure 2 An adjustment layer 130 is provided between the metal layer 120 and the base film layer 110. The adjustment layer 130 can serve as an intermediate transition structure, improving the interfacial compatibility between the metal layer 120 and the base film layer 110, filling the tiny gaps between them, and enhancing the bonding force between the interfaces. This alleviates the problem of poor bonding between the metal layer 120 and the base film layer 110 due to material differences. Consequently, it helps to improve the interfacial bonding performance between the metal layer 120 and the base film layer 110, enhances the interlayer bonding force and stability of the composite metal foil 100, further reduces the risk of delamination, and ensures the overall performance reliability of the composite metal foil 100.

[0055] Optionally, the conditioning layer 130 includes any one or a combination of two or more of coupling agents, organic polymers, or alloys.

[0056] For example, specific materials that can be selected include: coupling agents such as alkoxyamine salts and silane coupling agents; organic polymers such as epoxy resins, polyurethanes, and acrylic resins; and alloys such as aluminum-nickel alloys (Al-Ni), copper-nickel alloys (Cu-Ni), zinc-nickel alloys (Zn-Ni), and nickel-chromium alloys (Ni-Cr).

[0057] Specifically, coupling agents can enhance the interfacial bonding between the metal and the polymer base film, organic polymers can improve the flexibility and adhesion of the interface, alloys can improve the material compatibility between the metal layer 120 and the base film layer 110, and the combination of multiple materials can specifically optimize the interfacial bonding effect; thus, the material of the adjustment layer 130 is conducive to improving the compatibility and effect of the adjustment layer 130, which can enhance the diversity and stability of the bonding between the metal layer 120 and the base film layer 110, further enhance the interlayer bonding force of the composite metal foil 100, and improve the applicability of the composite metal foil 100 in different scenarios.

[0058] An embodiment of the present invention also provides a metal-clad laminate, comprising the high peel strength composite metal foil 100 of any one of the above.

[0059] The aforementioned metal-clad laminate, by utilizing the excellent interlayer bonding performance of the composite metal foil 100, enhances the bonding stability between the layers of the laminate, avoiding interlayer separation problems during processing or use. Beneficial effects: It helps improve the structural stability of the metal-clad laminate, enhances its anti-peeling ability, and thus helps improve the processing quality and reliability of the laminate in applications such as circuit fabrication.

[0060] For example, metal-clad laminates may specifically include copper-clad laminates (such as FR-4 copper-clad laminates, aluminum-based copper-clad laminates), aluminum foil laminates, copper foil polyimide laminates, stainless steel foil laminates, or other circuit board materials.

[0061] An embodiment of the present invention also provides a battery comprising a high peel strength composite metal foil 100 as described above.

[0062] The aforementioned battery uses the high peel strength composite metal foil 100. Utilizing the excellent interlayer bonding force and structural stability of the composite metal foil 100, delamination failure of the internal metal foil components is avoided, ensuring the continuity and structural integrity of the internal circuitry and reducing battery safety hazards caused by metal foil failure. Beneficial effects include: improved battery operational safety, enhanced structural stability and lifespan, improved energy density stability, and guaranteed overall battery performance.

[0063] To demonstrate the beneficial effects of the composite metal foil provided in the embodiments of the present invention, several embodiments and comparative examples are described below.

[0064] In the following examples and comparative examples, a copper metal layer (total thickness 6 μm) was prepared using a PET film (12 μm) as the base film layer through magnetron sputtering combined with electroplating. By precisely controlling the process conditions, different surface morphology structures were formed on the side of the metal layer close to the base film layer.

[0065] Example 1

[0066] Protrusion Structure: A two-stage protrusion design is employed. First protrusion: With an average height of 2.0 μm, it is an inverted triangle (wider at the base, narrower at the top) and accounts for 65% of all protrusions. The average distance between adjacent first protrusions is approximately 30 μm. Second protrusion: With an average height of 1.0 μm, its maximum width is located at approximately half its height. Four to five second protrusions are evenly distributed between at least 90% of adjacent first protrusions. Interface Characteristics: The three-dimensional roughness Sdr of the metal layer interface is 134.6%.

[0067] Example 2

[0068] Protrusion Structure: A two-tiered protrusion design is employed. First protrusion: Average height 4.5 μm, inverted triangular shape, accounting for approximately 70% of the total structure. The average spacing between adjacent protrusions is approximately 80 μm. Second protrusion: Average height 1.4 μm, with its maximum width located at approximately 2 / 3 of its height. Three to four second protrusions are distributed between approximately 60% of the adjacent first protrusions. Interface Characteristics: The metal layer interface is very rough, with an Sdr of 401.2%.

[0069] Example 3

[0070] Protrusion structure: Basically the same as in Example 1. First protrusion: Average height 2.2 μm, accounting for 68%, spacing approximately 35 μm. Second protrusion: Average height 1.1 μm, distribution density similar to Example 1. Interface characteristics: Metal layer bonding surface roughness Sdr is 178.9%. Adjustment layer: An adjustment layer was added. Before depositing the metal layer, a layer of silane coupling agent (KH-550) was coated on the PET base film.

[0071] Comparative Example 1

[0072] Protrusion Structure: No protrusions whatsoever. The side of the metal layer closest to the base film is polished to be as smooth and flat as possible. Interface Characteristics: Extremely smooth surface with a roughness Sdr of 5%.

[0073] Comparative Example 2

[0074] Protrusion Structure: Both protrusion height and density are insufficient. First protrusion: Average height 0.8 μm, accounting for 55%, sparsely spaced at approximately 120 μm. Second protrusion: Average height 0.3 μm, 1-2 scattered between adjacent first protrusions. Interface Characteristics: Surface remains relatively flat, Sdr is 21%. Adjustment Layer: Not provided.

[0075] Comparative Example 3

[0076] Protrusion Structure: The distribution of second protrusions is severely insufficient. First protrusions: Average height 2.5 μm, inverted triangular shape, accounting for 85%, with small spacing of approximately 25 μm. Second protrusions: Average height 1.2 μm, with one second protrusion existing between less than 10% of adjacent first protrusions. Interface characteristics: Sdr is 97.2%.

[0077] Comparative Example 4

[0078] Protrusion Structure: The macroscopic shape and distribution of the protrusions are similar to those in Example 1. First protrusion: Average height 2.1 μm, accounting for 66%, spacing approximately 32 μm. Second protrusion: Average height 1.0 μm, distribution density similar to Example 1. Interface Characteristics: Very low interface roughness. Despite the protrusions, the protrusion surfaces and surrounding metal layer are extremely smooth, with an overall Sdr of only 8.5%.

[0079] The composite metal foils prepared by the above methods were tested uniformly, and the key performance data are compared in Table 1 below:

[0080] Table 1

[0081]

[0082] Comparative analysis shows that Examples 1-3 all exhibited peel strengths higher than all comparative examples (50%-500% higher), demonstrating that a bi-level protrusion structure within a specific height range, combined with a design where at least 40% of adjacent first protrusions are interposed with second protrusions, can improve interlayer bonding. Comparative Example 2 shows that insufficient protrusion height prevents effective interlocking. Comparative Example 3 shows that insufficient distribution of second protrusions leads to discontinuous interlocking networks and reduced bonding strength. Comparative Example 4 shows that excessively low interface roughness (Sdr) weakens the mechanical locking effect of the protrusions. Example 3, based on the excellent mechanical structure of Example 1, further improved performance by adding an adjustment layer, demonstrating that the combination of physical mechanical interlocking and interface chemical modification yields the best results.

[0083] Furthermore, the higher peel strength directly translates into superior flexural strength and long-cycle stability. The battery capacity retention rates of Examples 1-3 are all significantly higher than those of the comparative examples, effectively addressing the battery performance degradation problem caused by current collector delamination.

[0084] 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.

[0085] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A high peel strength composite metal foil, characterized in that, It includes a base film layer and a metal layer. The base film layer has the metal layer disposed on at least one side. The metal layer has a plurality of protrusions on the side near the base film layer. The height of the protrusions is 0.5-5 μm. The protrusions include a first protrusion and a second protrusion. The height of the first protrusion is 1.5-5 μm and the height of the second protrusion is 0.5-1.5 μm. The second protrusion is provided between at least 40% of the adjacent first protrusions.

2. The high peel strength composite metal foil as described in claim 1, characterized in that, The distance between adjacent first protrusions is 10-100 μm.

3. The high peel strength composite metal foil as described in claim 1, characterized in that, The proportion of the first protrusion is more than 60%, and the average height of the first protrusion is 1.5-2.5μm.

4. The high peel strength composite metal foil as described in claim 1, characterized in that, The number of second protrusions between adjacent first protrusions is greater than or equal to 3.

5. The high peel strength composite metal foil as described in claim 1, characterized in that, The shape of the first protrusion includes an inverted triangle; Along the thickness direction, from one end face near the metal layer to the other, the width of the first protrusion gradually decreases.

6. The high peel strength composite metal foil as described in claim 5, characterized in that, The second protrusion is positioned at its maximum width away from the metal layer relative to the interface between the second protrusion and the metal layer.

7. The high peel strength composite metal foil as described in claim 6, characterized in that, The maximum width of the second protrusion is distributed between 1 / 4H and 3 / 4H of the height H of the second protrusion.

8. The high peel strength composite metal foil as described in claim 1, characterized in that, The roughness Sdr of the side of the metal layer near the base film layer is 30%-500%.

9. The high peel strength composite metal foil according to any one of claims 1-8, characterized in that, An adjustment layer is provided between the metal layer and the base film layer.

10. The high peel strength composite metal foil as described in claim 9, characterized in that, The conditioning layer comprises any one or a combination of two or more of coupling agents, organic polymers, or alloys.

11. A metal-clad laminate, characterized in that, Including high peel strength composite metal foil as described in any one of claims 1-10.

12. A battery, characterized in that, Including high peel strength composite metal foil as described in any one of claims 1-10.

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