A composite metal foil, a composite current collector, and a battery

Abstract

This invention discloses a composite metal foil, a composite current collector, and a battery. The composite metal foil includes a support layer and a metal layer, with the metal layer connected to at least one side of the support layer. The metal layer has at least one perforated structure, the shape of which includes a rhombus, and the perforated structure satisfies the following relationship: 5 ≤ L(1 - 1 / g) y )≤110, where g y L represents the number of perforations along the mechanical direction in the metal layer, and L is the side length of the rhomboid perforation. The technical solution provided by this invention solves the problem of insufficient elongation at break in the composite metal foil of the positive and negative electrodes of the battery, which affects the battery's lifespan.

Description

Technical Field

[0001] The present invention relates to the field of composite current collector technology, and in particular to a composite metal foil, a composite current collector, and a battery. Background Technology

[0002] With the deepening development of the new energy industry, energy storage equipment is receiving increasing attention. Copper foil is the negative electrode current collector material for lithium-ion batteries, accounting for 5%-10% of the cost of lithium-ion batteries. The negative electrode current collector for lithium-ion batteries requires high energy density, high safety performance, long service life, and lightweight design, which has become the development trend of negative electrode current collectors.

[0003] Existing metal foil technologies have the following problems: When composite metal foils are used as current collectors in battery fabrication, the battery interior undergoes contraction or expansion, thus requiring the current collector to meet a certain tensile strength. The elongation at break of the metal foil on the film is significantly lower than that of conventional metal foil current collectors, which can lead to breakage during use. This causes changes in the positive and negative electrode interfaces within the battery, resulting in degraded battery performance and impacting battery safety. Summary of the Invention

[0004] This invention provides a composite metal foil, a composite current collector, and a battery to solve the problem that the metal foils of the positive and negative electrodes of the battery have insufficient elongation at break, which affects the battery's service life.

[0005] To address the aforementioned technical problems, the present invention adopts the following technical solution:

[0006] This invention provides a composite metal foil, comprising: a support layer; a metal layer connected to at least one side of the support layer; the metal layer having at least one perforated structure, the perforated structure having a rhombus shape, and the perforated structure satisfying the following relationship:

[0007] 5≤L(1-1 / g) y )≤110 (1)

[0008] Among them, g y L represents the number of perforated structures along the mechanical direction in the metal layer per square decimeter, where L is the side length of the rhomboid perforated structure.

[0009] Optionally, the metal layer includes at least two perforated structures; adjacent perforated structures are spaced apart by their orthographic projections on the support layer; the perforated structures are arranged along a first direction; along the mechanical direction, adjacent rows of perforated structures are at least partially staggered to form a kirigami structure in the metal layer; wherein the first direction and the mechanical direction intersect.

[0010] Optionally, the side length of the hollow structure ranges from 0.01μm to 5mm.

[0011] Optionally, the hollow structure includes blind holes and / or through holes.

[0012] Optionally, the elongation at break of the composite metal foil ranges from 5% to 110%.

[0013] Optionally, the hollow structure has an arc-shaped portion at the included angle, and the adjacent two sides of the hollow structure are connected by the arc-shaped portion.

[0014] Optionally, the elongation at break of the support layer ranges from 20% to 200%.

[0015] Optionally, the thickness of the metal layer ranges from 0.5 μm to 5 μm.

[0016] Optionally, the support layer is connected to metal layers on both opposite sides, and each metal layer has multiple hollow structures.

[0017] Optionally, along the thickness direction of the support layer, the hollow structures located on opposite sides of the support layer have their orthographic projections on the support layer coincide.

[0018] Optionally, the support layer has openings, and a plurality of the openings are spaced apart on the support layer.

[0019] Optionally, the shape of the opening is the same as the shape of the hollow structure;

[0020] Along the thickness direction of the support layer, the hollow structure is provided corresponding to the opening.

[0021] Optionally, the hole wall of the opening is provided with a conductive part, which is electrically connected to the metal layer.

[0022] According to another aspect of the present invention, a composite current collector is provided, comprising: a composite metal foil as described in any of the first aspects.

[0023] According to a third aspect of the present invention, a battery is provided, comprising: a composite metal foil as described in any of the first aspects, or a composite current collector as described in the second aspect.

[0024] The composite metal foil provided in this embodiment of the invention includes a support layer and a metal layer, with the metal layer disposed on at least one side of the support layer. At least one perforated structure is formed in the metal layer, the shape of which includes a rhombus, and the perforated structure satisfies the following relationship: 5 ≤ L (1 - 1 / g) y )≤110; where, where, g yL represents the number of perforated structures along the mechanical direction of the metal layer, and L is the side length of the rhomboid perforated structure. This design significantly improves the toughness of the composite metal foil while ensuring its overall tensile strength, thereby greatly increasing its overall elongation at break. This solves the problem of insufficient elongation at break in composite metal foils for the positive and negative electrodes of batteries, and improves the service life of the positive or negative electrodes of batteries made from composite metal foils. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention 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 the content of the embodiments of the present invention and these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a composite metal foil in an unstretched state according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of a composite metal foil in a stretched state according to an embodiment of the present invention;

[0028] Figure 3 This is an embodiment of the present invention providing a composite metal foil along the edge Figure 1 A schematic diagram of the cross-section along the AA' direction;

[0029] Figure 4 This is a cross-sectional schematic diagram of another composite metal foil provided in an embodiment of the present invention;

[0030] Figure 5 This is a cross-sectional schematic diagram of another composite metal foil provided in an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of another composite metal foil in a stretched state provided by an embodiment of the present invention;

[0032] Figure 7 This is a cross-sectional schematic diagram of another composite metal foil provided in an embodiment of the present invention;

[0033] Figure 8 This is a cross-sectional schematic diagram of another composite metal foil provided in an embodiment of the present invention;

[0034] Figure 9 This is a cross-sectional schematic diagram of another composite metal foil provided in an embodiment of the present invention. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0036] Based on the above-mentioned technical problems, this embodiment proposes the following solutions:

[0037] Figure 1 This is a schematic diagram of the structure of a composite metal foil in an unstretched state according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a composite metal foil in a stretched state according to an embodiment of the present invention. Figure 3 This is an embodiment of the present invention providing a composite metal foil along the edge Figure 1 A schematic diagram of the cross-section along the AA' direction. (Combined with...) Figures 1 to 3 The composite metal foil 10 provided in this embodiment includes a support layer 1; a metal layer 2, the metal layer 2 being connected to at least one side of the support layer 1; and the metal layer 2 having at least one hollow structure 3, the hollow structure 3 having a rhombus shape, and the hollow structure 3 satisfying the following relationship:

[0038] 5≤L(1-1 / g) y )≤110 (1)

[0039] Among them, g y L represents the number of perforated structures along the mechanical direction in the metal layer per square decimeter, where L is the side length of the rhomboid perforated structure, in μm.

[0040] Specifically, the composite metal foil 10 includes a support layer 1 and a metal layer 2, with the metal layer 2 connected to the support. The support layer 1 serves as a substrate, providing support for the metal layer 2. The metal layer 2 can be disposed on one or both sides of the support layer 1, without any limitation. The metal layer 2 has at least one perforated structure 3, the shape of which includes a rhombus. The rhombus-shaped perforated structure 3 can include through holes or blind holes. When the rhombus-shaped perforated structure 3 includes blind holes, the rhombus-shaped perforated structure 3 can be distributed along a predetermined direction on the side of the metal layer 2 closest to the support layer 1. Alternatively, the rhombus-shaped perforated structure 3 can be distributed along a predetermined direction on the side of the metal layer 2 away from the support layer 1.

[0041] When the composite metal foil 10 is mechanically stretched and deformed, the toughness of the metal layer 2 is much less than that of the support layer 1. When the stress in the metal layer 2 concentrates and fractures, it will cause the support layer 1 to fracture. By creating multiple rhomboid perforated structures 3 on the metal layer 2, the stress in the metal layer 2 can be dispersed when the support layer 1 undergoes plastic deformation. The perforated structures 3 guide the metal layer 2 to undergo elastic deformation, thus allowing it to follow the support layer 1 in elastic or plastic deformation.

[0042] In the production of roll materials such as metal foil, fabric, paper, and film, "MD direction" and "TD direction" refer to different orientations of the roll material. The MD direction (Machine Direction) refers to the machine stretching or production direction of the roll material during manufacturing, also known as the longitudinal direction. The TD direction (Transverse Direction) refers to the direction of the roll material perpendicular to the MD direction, also known as the transverse direction. Both the MD and TD directions have a significant impact on the manufacturing, processing, and application of roll materials.

[0043] For example, in some applications, it is necessary to consider the mechanical and electrical properties of the composite metal foil 10 in different directions to ensure that it meets specific requirements. The short axis of the rhomboid perforated structure 3 is the same as the mechanical direction, i.e., the MD direction.

[0044] The more perforated structures 3 there are in the MD direction, the longer the perforated structures 3 in the MD direction can be increased. By controlling the side length of the rhomboid perforated structures 3 and the number of rhomboid perforated structures 3 in the MD direction, it is beneficial to significantly improve the toughness of the composite metal foil 10 while ensuring the overall tensile strength of the composite metal foil 10, thereby greatly improving the elongation at break of the composite metal foil 10.

[0045] By setting the side length L of the rhomboid hollow structure 3 to satisfy the following relationship: 5≤L(1-1 / g) y The value of the rhomboid hollow structure 3 is ≤110, allowing it to accommodate a fixed amount of deformation along the mechanical direction. By controlling the range of the side length L of the rhomboid hollow structure 3, it is beneficial to significantly improve the toughness of the composite metal foil 10 while ensuring its overall tensile strength, thereby greatly increasing the overall elongation at break of the composite metal foil 10. When the side length of the rhomboid hollow structure 3 exceeds this range, the overall strength of the composite copper foil 10 is low; when the side length of the rhomboid hollow structure 3 is less than this range, the overall toughness of the composite copper foil is low, failing to meet the working requirements of the current collector in the battery.

[0046] The composite metal foil 10 provided in this embodiment includes a support layer 1 and a metal layer 2, with the metal layer 2 disposed on at least one side of the support layer 1. At least one perforated structure 3 is formed in the metal layer 2. The shape of the perforated structure 3 includes a rhombus, and the perforated structure 3 satisfies the following relationship: 5 ≤ L (1 - 1 / g) y )≤110; where, where, g yL represents the number of the perforated structures 3 along the mechanical direction of the metal layer, and L is the side length of the rhomboid perforated structure 3. This arrangement ensures the overall tensile strength of the composite metal foil 10 while significantly improving its toughness, thereby greatly increasing the overall elongation at break of the composite metal foil 10. This solves the problem of insufficient elongation at break in the composite metal foil 10 for the positive and negative electrodes of the battery, and improves the service life of the positive or negative electrode of the battery made from the composite metal foil 10.

[0047] Optionally, based on the above embodiments, see also... Figure 1 The metal layer 2 includes at least two hollow structures 3; the orthographic projections of adjacent hollow structures 3 on the support layer 1 are spaced apart; the hollow structures 3 are arranged along the first direction N1; along the mechanical direction, the hollow structures 3 in adjacent rows are at least partially staggered so that the metal layer 2 forms a kirigami structure; wherein the first direction N1 intersects the mechanical direction and the first direction N1 is not perpendicular to the mechanical direction.

[0048] Specifically, the orthographic projections of adjacent hollow structures 3 onto the support layer 1 are spaced apart, allowing the hollow structures 3 to be independent of each other. The first direction N1 can be a direction that intersects both the TD direction and the mechanical direction; for example, see [reference needed]. Figure 1 The angle between the first direction N1 and the mechanical direction is an obtuse angle, and the angle between the first direction N1 and the TD direction is an acute angle, such as 15°, 30°, 45°, 50° or 70°. By setting the hollow structure 3 along the first direction N1 and along the mechanical direction, i.e. MD, the metal layer 2 forms a kirigami structure with elasticity and ductility.

[0049] Kirigami structures, also known as paper-cutting structures, refer to materials science processes where materials are cut and folded in a manner similar to paper cutting to achieve desired deformation and properties. Kirigami structures significantly influence a material's toughness. Toughness is a material's ability to resist fracture and deformation; that is, its property of being able to stretch and deform without breaking under external forces.

[0050] By designing and manufacturing a Kirigami-like structure for the metal layer 1 on the composite metal foil 10, the following effects can be achieved: First, increased deformable area: The Kirigami structure design increases the deformable area of ​​the material, allowing it to deform to a greater extent. The cut geometry can provide additional elastic energy storage, helping to delay fracture. Second, dispersion of stress concentration: The Kirigami structure can effectively disperse stress concentration, distributing stress to the cut area, thereby reducing the stress concentration that the original material might experience. This reduces the risk of fracture and improves the toughness of the material. Third, increased stress release pathways: By designing the Kirigami structure, more stress release pathways can be provided for the material. Through specific cutting patterns, the composite metal foil 10 material can reduce stress concentration by releasing or redistributing stress when under stress, thereby increasing toughness.

[0051] By incorporating a multi-rhomboid perforated structure 3 onto the metal layer 2 to form a Kirigami structure, the toughness of the metal layer 2 can be improved by increasing its deformable area, dispersing stress concentration, and increasing stress release pathways. This, in turn, enhances the overall toughness of the composite metal foil 10 and consequently increases its overall elongation at break. Furthermore, compared to traditional perforated mesh composite metal foils 10, the Kirigami structure composite metal foil 10, through the rhomboid perforated structure 3 guiding elastic and plastic deformation in the MD direction, can significantly improve deformation efficiency, thereby substantially increasing the elongation at break of the composite metal foil 10.

[0052] Optionally, based on the above embodiments, see also... Figure 1 The side length L of the hollow structure ranges from 0.01μm to 5mm.

[0053] Specifically, by controlling the range of the side length L of the rhomboid hollow structure, the toughness of the metal layer 2 can be improved while ensuring the overall tensile strength of the composite metal foil 10. This guides the elastic deformation of the metal layer 2, releases concentrated stress, and allows the metal layer 2 to stretch along with the support layer 1, reducing shear deformation and ensuring a high elongation at break. If the side length L of the hollow structure 3 exceeds 5mm, the hollow structure 3 becomes too large, extending the current transmission path and affecting the current transmission efficiency in the metal layer 2.

[0054] Optional, Figure 4 This is a cross-sectional schematic diagram of another composite metal foil provided in an embodiment of the present invention. Figure 5 This is a cross-sectional schematic diagram of another composite metal foil provided in an embodiment of the present invention. Based on the above embodiments, and in conjunction with... Figure 4 and Figure 5 The hollow structure 3 includes blind holes and / or through holes.

[0055] It should be noted that the hollow structure 3, including blind holes and / or through holes, should be understood as meaning that a single metal layer 2 may only have hollow structures 3 in the form of blind holes, or only have hollow structures 3 in the form of through holes, or may include hollow structures 3 in both the form of blind holes and through holes. Furthermore, the depth of the blind holes is not specifically limited here.

[0056] For details, see Figure 5 The blind hole design means that the side of the metal layer 2 closest to the support layer 1 is a complete plane. This design ensures the bonding strength between the metal layer 2 and the support layer 1, preventing the metal layer 2 from detaching from the support layer 1. See also Figure 4 The through-holes are formed by the hollow structure 3 extending to one side of the support layer 1. The through-holes can better guide the overall deformation of the metal layer 2, thereby improving the overall elongation at break of the composite metal foil 10.

[0057] Optionally, based on the above embodiments, see also... Figure 1 The elongation at break of the composite metal foil 10 can range from 5% to 110%.

[0058] Specifically, elongation at break is a mechanical property of materials, used to measure the extent to which a material can stretch before fracture. Elongation at break is the maximum tensile deformation a material can withstand before breaking, usually expressed as a percentage. It is an important indicator of a material's tensile strength and toughness. Elongation at break is related to a material's ductility and plasticity. When a material is subjected to tensile load, it deforms, which can lead to fracture or breakage. Elongation at break measures the tensile deformation that occurs when a material fractures, that is, the length the material can stretch before tensile fracture.

[0059] For example, a method for measuring elongation at break includes:

[0060] Step 1: Sample Preparation: Prepare a composite metal foil 10 sample that meets the requirements according to the standards or requirements of the material being tested. Typically, the composite metal foil 10 sample is rectangular in shape, with specific dimensional requirements, such as length, width, and thickness.

[0061] Step 2: Install the sample: Use a clamp or fixture to clamp the composite metal foil 10 sample, ensuring that one end of the composite metal foil 10 sample is fixed and the other end can extend freely.

[0062] Step 3: Apply load: Using appropriate loading equipment, such as a tensile machine, apply uniform tensile or compressive force to the composite metal foil 10 sample to allow the composite metal foil 10 sample to begin to stretch.

[0063] Step 4: Measure the elongation: When the composite metal foil 10 sample begins to break, use an elongation meter or measuring gauge to measure the original length (Lo) and the final length (Lf) of the sample after breakage.

[0064] Step 5: Calculate the elongation at break: Calculate the elongation at break using the following formula: Elongation at Break = ((Lf - Lo) / Lo) * 100%; where Elongation at Break represents the elongation at break, Lf represents the final length of the specimen after breakage, and Lo represents the original length of the specimen. The calculation processes in steps four and five can be automatically generated by the experimental equipment.

[0065] By setting the elongation at break of the composite metal foil 10 to a range of 5% to 110%, within this range, the composite metal foil 10, as the current collector material of the battery, can meet the requirements of the tensile force during winding and the expansion of the material during battery use, ensuring the working stability of the composite current collector and thus ensuring the reliability of the lithium battery.

[0066] Optional, Figure 6 This is a schematic diagram of another composite metal foil 10 provided in an embodiment of the present invention when it is in a stretched state. Based on the above embodiments, see... Figure 6 The hollow structure 3 has an arc-shaped part 5 at the included angle, and the two adjacent sides of the hollow structure 3 are connected by the arc-shaped part 5.

[0067] Specifically, the corner of the hollow structure 3 is transitioned by an arc-shaped part 5, similar to rounded corner treatment, which can further disperse the stress at the connection between adjacent sides of the hollow structure 3, avoid stress concentration, prevent the corner of the hollow structure 3 from breaking, and improve the overall strength and tear resistance of the composite metal foil 10.

[0068] Alternatively, the shape of the arc-shaped part can be circular or wavy.

[0069] Optionally, based on the above embodiments, see also... Figure 1 The elongation at break of the support layer 1 ranges from 20% to 200%.

[0070] Specifically, the elongation at break of the support layer 1 ranges from 20% to 200%, which helps to meet the stretching caused by the expansion of the positive and negative current collectors during the charging and discharging of the positive and negative electrode materials, avoids the breakage of the composite metal foil 10, and ensures the working reliability of the battery.

[0071] As one optional implementation, the elongation at break of the support layer 1 ranges from 50% to 300%. The support layer 1 is used as a support material in the battery current collector to reduce the use of copper, increase energy density, significantly reduce the weight of pure metal foil in traditional current collectors, meet the stretching caused by the expansion of the positive and negative electrode current collectors during the charging and discharging of the positive and negative electrode materials, avoid the composite metal foil 10 from breaking, and ensure the working reliability of the battery.

[0072] Optionally, based on the above embodiments, see also... Figure 1 The thickness of the metal layer 2 can range from 0.5 μm to 5 μm.

[0073] Specifically, the thickness of metal layer 2 affects its toughness and rigidity, thus influencing the overall toughness of the composite metal foil 10. A thicker metal layer 2 results in lower sheet resistance but lower toughness and tensile strength. Conversely, a thinner metal layer 2 results in higher sheet resistance, affecting overall conductivity and the welding strength of the electrode tabs. Setting the thickness of metal layer 2 within the range of 0.5μm to 5μm satisfies the overall elongation at break of the composite metal foil 10, ensuring high tensile strength and addressing the expansion issues of the battery's positive and negative electrode materials during charging and discharging. It also guarantees stable current transmission and electrode tab welding.

[0074] Optionally, based on the above embodiments, further combinations can be made... Figure 4 and Figure 5 The support layer 1 has metal layers 2 connected to its two opposite sides, and each metal layer 2 has multiple hollow structures 3.

[0075] Specifically, the composite metal foil 10 with double-sided metal layers 2 can meet different application scenarios and is beneficial to improving energy density. The metal layers 2 are connected to both opposite sides of the support layer 1, and both sides of the metal layers 2 have hollow structures 3, which can guide deformation on both sides of the support layer 1, thereby further improving the toughness of the composite metal foil 10.

[0076] It should be noted that, Figure 4 An example is shown where the perforated structure 3 of the metal layer 2 located on both sides of the support layer 1 includes through holes. Figure 5 An exemplary illustration shows that the perforated structures 3 of the metal layers 2 on both sides of the support layer 1 both include blind holes. Alternatively, the perforated structures 3 of the metal layers 2 on both sides of the support layer 1 may be configured to include both blind holes and through holes, depending on the need. Or, depending on the need, the perforated structure 3 of the metal layer 2 on one side of the support layer 1 may include blind holes, while the perforated structure 3 of the metal layer 2 on the opposite side of the support layer 1 may include through holes; no limitation is made here.

[0077] In one optional embodiment, the metal layer 2 can be made of copper, aluminum, gold, silver, iron, zinc, tungsten, nickel, chromium, or an alloy containing at least two of these elements. Optionally, when the metal layer 2 is copper, it forms a negative electrode current collector material. When the metal layer 2 is aluminum, it forms a positive electrode current collector material.

[0078] Optionally, the metal layer 2 can be formed on the support layer 1 by bonding, pressing, sputtering, high-temperature evaporation or other methods.

[0079] Specifically, in this embodiment, the metal layer 2 includes a vacuum layer and a thickening layer. The vacuum layer is formed on the support layer 1 by vacuum sputtering, and the thickening layer is formed on the vacuum layer by electroplating. In this way, the bonding force between the metal layer 2 and the support layer 1 can be guaranteed, preventing the metal layer 2 from falling off. Furthermore, the electroplated metal layer 2 is easy to process and has a uniform structure, which helps to ensure the overall quality of the composite metal foil.

[0080] Another alternative implementation, based on the above embodiments, continues to refer to... Figure 1 The material of the support layer 1 may include at least one of PET (polyethylene terephthalate), PI (polyimide), PE (polyethylene), PS (polystyrene), PVC (polyvinyl chloride) or PP (polypropylene); the thickness of the support layer 1 ranges from 2μm to 200μm.

[0081] Specifically, the support layer 1 serves as a supporting material in the battery current collector. The material used for the support layer 1 can include at least one of PET, PI, or PP, such as PET. This reduces the use of copper, increases the energy density of the composite metal foil 10, and significantly reduces its weight. As a weight-reducing supporting material, the thickness of the support layer 1 is set to range from 2μm to 200μm to meet different application scenarios and ensure the overall tensile strength of the composite metal foil 10.

[0082] Optionally, the hollow structures 3 on the metal layers 2 on both sides of the support layer 1 can be aligned or staggered in the thickness direction of the support layer 1.

[0083] Specifically, Figure 7 This is a cross-sectional schematic diagram of another composite metal foil provided in an embodiment of the present invention. Figure 8 This is a cross-sectional schematic diagram of another composite metal foil provided in an embodiment of the present invention. Figure 9This is a cross-sectional schematic diagram of another composite metal foil provided in an embodiment of the present invention. Based on the above embodiments, and in conjunction with... Figures 7 to 9 Along the thickness direction of the support layer 1, the hollow structures 3 located on opposite sides of the support layer 1 overlap in the orthographic projection of the support layer 1.

[0084] Along the thickness direction of the support layer 1, the hollow structures 3 located on opposite sides of the support layer 1 overlap in the orthographic projection of the support layer 1, making the metal layers 2 located on both sides of the support layer 1 symmetrical. When the composite metal foil 10 is stretched, the deformation of the two sides of the support layer 1 can be synchronized, avoiding uneven stress on the upper and lower sides of the support layer 1 during the stretching process, which may lead to curling or even shear deformation.

[0085] Optionally, based on the above embodiments, further combinations can be made... Figures 7 to 9 The support layer 1 has openings 4, and multiple openings 4 are spaced apart on the support layer 1.

[0086] Specifically, openings 4 in the support layer 1 can further improve the ductility of the support layer 1. Multiple openings 4 are spaced apart on the support layer 1, ensuring both the ductility of the support layer and the mechanical strength of the support layer 1. Openings 4 can be, but are not limited to, blind holes, slots, or through holes. The shape of the openings 4 can be the same as or different from the shape of the hollow structure 3; no limitations are imposed here.

[0087] In one alternative implementation, the opening 4 may include a blind hole, which can both improve the support capacity of the support layer 1 and improve the ductility of the support layer 1.

[0088] In another alternative implementation, opening 4 may include a first through hole, which can further improve the ductility of support layer 1.

[0089] Optionally, based on the above embodiments, further combinations can be made... Figures 7 to 9 The shape of the opening 4 is the same as the shape of the hollow structure 3; along the thickness direction of the support layer 1, the hollow structure 3 and the opening 4 are set accordingly.

[0090] Specifically, this design further guides the synchronous elastic deformation of the support layer 1 and the metal layer 2, thereby ensuring the overall structural stability of the composite metal foil 10. Setting the shape of the opening 4 to be the same as the shape of the hollow structure 3 reduces the complexity of the manufacturing process.

[0091] It should be noted that, Figure 7 An example is shown where the perforated structure 3 of the metal layer 2 located on both sides of the support layer 1 includes blind holes. Figure 8 An exemplary case is shown where the perforated structure 3 of the metal layer 2 located on one side of the support layer 1 includes through holes, while the perforated structure 3 of the metal layer 2 located on the opposite side of the support layer 1 includes blind holes. Figure 9An example is shown where the perforated structure 3 of the metal layer 2 located on both sides of the support layer 1 includes through holes, but no limitation is made here.

[0092] Optionally, based on the above embodiments, further combinations can be made... Figures 7 to 9 The hole wall of opening 4 is provided with a conductive part (not shown in the figure), which is electrically connected to the metal layer 2.

[0093] Specifically, this design helps to improve the service life of the composite metal foil 10 and the bonding force between the metal layer 2 and the support layer 1, prevents the metal layer 2 from falling off the support layer 1, and also avoids open circuits, ensuring the working stability of the battery.

[0094] Embodiments of the present invention provide a composite current collector. The composite current collector provided by the embodiments of the present invention includes the composite metal foil proposed in any of the above embodiments, and has the beneficial effects of the composite metal foil proposed in any of the above embodiments, which will not be repeated here.

[0095] Embodiments of the present invention provide a battery. The battery provided by the embodiments of the present invention includes the composite metal foil proposed in any of the above embodiments, or includes the composite current collector proposed in any of the above embodiments, and has the beneficial effects of the composite metal foil or composite current collector proposed in any of the above embodiments, which will not be repeated here.

[0096] Example 1:

[0097] The composite metal foil 10 includes a support layer 1 and a metal layer 2 disposed on one side of the support layer 1. The support layer 1 has a thickness of 6 μm, and the metal layer 2 has a thickness of 1.2 μm. The metal layer 2 has as follows... Figure 1 The hollow structure 3 shown is rhomboid in shape, g y There are 2, and L is 150μm.

[0098] Example 2:

[0099] The composite metal foil 10 includes a support layer 1 and a metal layer 2 disposed on one side of the support layer 1. The support layer 1 has a thickness of 4.5 μm, and the metal layer 2 has a thickness of 2 μm. The metal layer 2 has as follows... Figure 1 The hollow structure 3 shown is rhomboid in shape, g y There are 6, and L is 120μm.

[0100] Example 3:

[0101] The composite metal foil 10 includes a support layer 1 and two metal layers 2 disposed on both sides of the support layer 1. The support layer 1 has a thickness of 6 μm, and the metal layers 2 have a thickness of 2 μm. The metal layers 2 are provided with... Figure 1 The hollow structure 3 shown is rhomboid in shape, g yThere are 8, and L is 100μm.

[0102] Example 4:

[0103] Example 4 has the same structure as Example 1, the difference being that g y There are 20, and L is 60μm.

[0104] Comparative Example 1:

[0105] The composite copper foil consists of a support layer and a metal layer. The support layer is 6mm thick and the metal layer is 11mm thick, with no perforated structure.

[0106] Comparative Example 2:

[0107] The composite copper foil comprises a support layer 1 and a metal layer 2. The support layer 1 has a thickness of 5.5 μm, and the metal layer 2 has a thickness of 2 μm. The metal layer 2 has as follows... Figure 1 The hollow structure 3 shown is rhomboid in shape, g y There are 15, and L is 160μm.

[0108] The fracture rate of the composite metal foils described in the examples and comparative examples was measured, and the experimental results are shown in Table 1:

[0109]

[0110] Experimental data from the examples and comparative examples show that the rhomboid hollow structure can significantly improve the elongation at break of the composite metal foil. Comparative example 2 cracked during stretching, making it impossible to measure the elongation at break of the sample normally.

[0111] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A composite metal foil, characterized in that, include: Support layer; A metal layer is connected to at least one side of the support layer; the metal layer has at least one perforated structure, the shape of the perforated structure includes a rhombus, and the perforated structure satisfies the following relationship: 5≤L(1-1 / g y )≤110 (1) Among them, g y L represents the number of perforated structures along the mechanical direction in the metal layer per square decimeter, where L is the side length of the rhomboid perforated structure, in μm. The metal layer includes at least two of the hollow structures; adjacent hollow structures are spaced apart by their orthographic projections on the support layer; the hollow structures are arranged along a first direction; along the mechanical direction, adjacent rows of hollow structures are at least partially staggered to form a paper-cut structure in the metal layer; wherein the first direction and the mechanical direction intersect. The side length of the hollow structure ranges from 0.01μm to 5mm.

2. The composite metal foil according to claim 1, characterized in that, The hollow structure includes blind holes and / or through holes.

3. The composite metal foil according to claim 1, characterized in that, The elongation at break of the composite metal foil ranges from 5% to 110%.

4. The composite metal foil according to claim 1, characterized in that, The hollow structure has an arc-shaped section at the included angle, and the two adjacent sides of the hollow structure are connected by the arc-shaped section.

5. The composite metal foil according to claim 1, characterized in that, The elongation at break of the support layer ranges from 20% to 200%.

6. The composite metal foil according to claim 1, characterized in that, The thickness of the metal layer ranges from 0.5 μm to 5 μm.

7. The composite metal foil according to claim 1, characterized in that, The support layer is connected to metal layers on both opposite sides, and each metal layer has multiple hollow structures.

8. The composite metal foil according to claim 7, characterized in that, Along the thickness direction of the support layer, the hollow structures located on opposite sides of the support layer have their orthogonal projections on the support layer coincide.

9. The composite metal foil according to any one of claims 2-8, characterized in that, The support layer has openings, and multiple openings are spaced apart on the support layer.

10. The composite metal foil according to claim 9, characterized in that, The shape of the opening is the same as the shape of the hollow structure; along the thickness direction of the support layer, the hollow structure and the opening are arranged correspondingly.

11. The composite metal foil according to claim 9, characterized in that, The opening has a conductive portion on its wall, and the conductive portion is electrically connected to the metal layer.

12. A composite current collector, characterized in that, include: The composite metal foil according to any one of claims 1-11.

13. A battery, characterized in that, include: The composite metal foil according to any one of claims 1-11, or the composite current collector according to claim 12.

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