Metal foil for current collector, current collector for battery manufactured using same, and secondary battery including current collector

Abstract

The present invention relates to a metal foil for a current collector, a current collector for a battery, and a secondary battery comprising the same, the metal foil for a current collector comprising: a first cutout part comprising a plurality of first cutout lines formed at intervals in a first direction; the first cutting part comprises a plurality of first cutting lines formed in the first direction in a spaced mode, the second cutting part comprises a plurality of second cutting lines formed in the first direction in a spaced mode, and the first cutting part and the second cutting part are arranged in parallel and alternately in the second direction perpendicular to the first direction; the plurality of first cut-out lines and the plurality of second cut-out lines are spaced apart from each other in a zigzag arrangement so that the ends of the cut-out lines overlap each other to form an overlapping portion, and satisfy specific relational expressions 1 and 2.

Description

Technical Field

[0001] The present invention relates to a metal foil for a current collector, a current collector for a battery, and a secondary battery including the current collector. More specifically, the present invention relates to a metal foil for a current collector, a current collector for a battery, and a secondary battery including the current collector, which can manufacture a mesh-shaped current collector having excellent binding force with a negative electrode active material. Background Art

[0002] Compared with other secondary batteries, lithium secondary batteries not only have a relatively high energy density and operating voltage, but also have various advantages such as excellent storage and life characteristics. Therefore, they are widely used in various portable electronic devices such as personal computers, computers, mobile phones, personal digital assistants (PDAs), tablet computers, and electric vehicles.

[0003] In such a lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material coated (attached) on the surface of the negative electrode current collector. The material of the negative electrode current collector is usually a copper foil, especially an electrolytic copper foil. However, since the electrolytic copper foil is manufactured by an electroplating method, the roughness of both surfaces is different. Therefore, when the electrolytic copper foil is used as the negative electrode current collector, the coating amount of the active material between the two surfaces of the current collector is different, and thus, the capacity attenuation or instability of the electrode may be caused by the deformation difference between the two surfaces.

[0004] On the other hand, in order to improve the charge-discharge cycle characteristics of a lithium secondary battery, a silicon-based negative electrode active material is used as the negative electrode active material. However, the silicon-based negative electrode active material undergoes a severe volume change of about 300% or more during the charge and discharge of the lithium secondary battery. Therefore, the negative electrode active material is peeled off and detached from the negative electrode current collector, resulting in an internal short circuit, which not only reduces the life of the electrode but also reduces the battery efficiency. Summary of the Invention

[0005] Technical Problem

[0006] An object of the present invention is to provide a metal foil that can economically and environmentally manufacture a current collector for a battery having excellent binding force with an active material.

[0007] Another object of the present invention is to provide a current collector for a battery having excellent binding force with an active material prepared by using the aforementioned metal foil.

[0008] And, by manufacturing the metal foil in a mesh form, a current collector for a battery is provided in which even if there is a slight difference in the coating amount of the active material on both sides, the influence on the battery characteristics is small.

[0009] Still another object of the present invention is to provide an electrode for a secondary battery using the aforementioned current collector and a secondary battery including the electrode.

[0010] Means for Solving the Problem

[0011] In order to solve the foregoing technical problems, the present invention provides a metal foil for a current collector, including: a first cut portion including a plurality of first cut lines spaced apart in a first direction; and a second cut portion including a plurality of second cut lines spaced apart in the first direction. The first cut portion and the second cut portion are each plural, and are alternately spaced apart in parallel in a second direction perpendicular to the first direction. The plurality of first cut lines and the plurality of second cut lines are arranged in a zigzag pattern such that the ends of the respective cut lines overlap to form an overlapping portion. The following relational expressions 1 and 2 are satisfied. Relational expression 1: Relational expression 2:

[0012] In the relational expressions, T1 is the thickness of the relevant metal foil, D1 is the separation distance between adjacent first cut portions and second cut portions, and L1 is the length of the overlapping portion.

[0013] According to an example of the present invention, the ratio of the roughness (Rz) of the matte surface of the metal foil to the thickness T1 of the relevant metal foil is in the range of 0.1 to 0.5.

[0014] Moreover, according to an example of the present invention, the tensile strength of the relevant metal foil can be 30 kgf / mm 2 to 90 kgf / mm 2 , and the elongation rate can be in the range of 2% to 20%.

[0015] Moreover, according to an example of the present invention, the relevant metal foil can have a thickness in the range of 6 μm to 30 μm.

[0016] Moreover, according to an example of the present invention, the metal of the relevant metal foil can be selected from the group consisting of copper (Cu), aluminum (Al), nickel (Ni), iron (Fe), silver (Ag), gold (Au), tungsten (W), tin (Sn), platinum (Pt), palladium (Pd), and alloys thereof.

[0017] Moreover, the present invention provides a current collector for a battery, including a metal mesh layer formed by stamping after unfolding the metal foil, which is composed of a wire portion and a diamond-shaped opening portion. The wire portion satisfies the following relational expressions 3 and 4. Relational expression 3: Relational expression 4:

[0018] In the relational expressions, T1 is the thickness of the metal mesh layer, W1 is the wire width of the wire portion, and P1 is the wire pitch of the wire portion.

[0019] According to an example of the present invention, the porosity of the current collector for a battery is 10% to 300%.

[0020] According to an example of the present invention, the current collector for a battery may further include a surface treatment layer provided on at least one surface of the metal mesh layer.

[0021] Moreover, the present invention provides an electrode for a secondary battery, including: the current collector; and an active material layer provided on both surfaces of the current collector.

[0022] According to an example of the present invention, in the electrode for a secondary battery, the current collector may further include a surface treatment layer provided on at least one surface of the metal mesh layer.

[0023] According to an example of the present invention, in the electrode for a secondary battery, the active material layer may contain a silicon-based active material.

[0024] Moreover, the present invention provides a secondary battery including the electrode.

[0025] Effects of the Invention

[0026] In the present invention, a plurality of cut lines are provided at intervals in a zigzag arrangement of the metal foil, and a grid-type current collector with excellent bonding force between active materials can be economically and environmentally manufactured by adjusting the interval distance thereof to a specific range. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The top view for briefly showing the metal foil for a current collector according to the first embodiment of the present invention.

[0028] Figure 2 The top view for briefly showing the current collector for a battery according to the second embodiment of the present invention.

[0029] Figure 3 The top view for briefly showing the case of measuring whether the active material is peeled off in Experimental Example 1.

[0030] **Description of Reference Numerals** 10: First cut portion 11: First cut line 20: Second cut portion 21: Second cut line 100: Metal foil 100A: Metal mesh layer DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, the present invention will be described in detail.

[0032] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification shall be construed in accordance with the ordinary meaning as commonly understood by those of ordinary skill in the art to which this invention pertains. Also, unless specifically defined otherwise, they shall not be construed in an idealized or exaggerated form.

[0033] Also, throughout this specification, when a certain part is referred to as "comprising" a structural element, unless there is a specific contrary statement, it should be understood as an open-ended term that includes the possibility of also including other structural elements, rather than excluding other structural elements. Also, throughout this specification, "upper" or "upper part" not only refers to the upper or lower situation of an object part, but also includes cases where other parts are in between, and does not mean that it must be the upper side based on the direction of gravity. Moreover, in this specification, terms such as "first", "second", etc. do not represent any arbitrary order or degree of importance, but are used to distinguish between structural elements.

[0034] Also, "preferred" or "preferably" used in this specification refers to an embodiment of the present invention that can provide a specified advantage under a specified environment. However, in the same environment or other environments, other embodiments may also be preferred. Additionally, when more than one preferred embodiment is mentioned, it does not mean that other embodiments are useless, nor is it intended to exclude other embodiments from the scope of the present invention.

[0035] <Metal foil for current collector>

[0036] Generally, the thinner the thickness of a metal foil (e.g., copper foil), the lower the elongation rate. In the case of applying such a thin metal foil as the negative electrode current collector of a battery, high-capacity characteristics of the battery can be achieved by increasing the loading of the active material. However, if the volume of the active material changes during charge and discharge of the secondary battery, the thin metal foil is prone to tearing due to its low elongation rate, resulting in a reduction in battery performance and safety. Also, since the metal foil is in a plate form, when the active material is coated on both sides of the metal foil, at least two coating processes are required, which causes an increase in the manufacturing time and cost of the current collector.

[0037] To solve such problems, the present invention has found that when using a metal foil in a mesh form instead of a plate form as the current collector, not only can the bonding force between the metal foil and the active material be improved, but also the active material can be coated on both sides of the current collector through a single coating process. However, if a plurality of opening portions are formed in the plate-form metal foil by etching, punching, or laser processing, the loss of the metal plate is too large. Moreover, if a chemical process such as etching is used, environmental pollution will be caused by the etching waste liquid.

[0038] Therefore, in the present invention, after forming a zigzag arrangement of cut lines (sheaths) in a plate-shaped metal foil, it is unfolded and stamped, so that a grid-shaped current collector can be manufactured without environmental pollution and metal plate loss.

[0039] However, the present invention has found that the manufacturability of the grid-shaped current collector is not only affected by the separation distance between adjacent cut lines, the length of the overlapping portion at both ends of the cut line, and the difference in whether the metal foil with multiple cut lines formed according to the ratio between them and the thickness of the metal foil is unfolded or not, but also the difference in the aperture ratio of the grid-shaped current collector will affect the bonding force of the active material coated on the current collector. And the present invention has found that the separation distance between adjacent cut lines and the length of the overlapping portion relative to the thickness of the metal foil will also affect the tensile strength and elongation of the grid-shaped current collector.

[0040] Thus, the metal foil for a current collector of the present invention includes a plurality of cut lines spaced apart in a zigzag arrangement, and the separation distance between adjacent cut lines and the length of the overlapping portion where the ends of each cut line overlap are respectively adjusted to a specific range based on the thickness of the metal foil. In this way, the metal foil for a current collector of the present invention can economically and environmentally manufacture a grid-shaped current collector through unfolding and stamping processes. The grid-shaped current collector of the present invention manufactured as described above can coat the active material on both surfaces through a single coating process, and thus can withstand the volume change of the active material due to the excellent bonding force between the active materials.

[0041] Hereinafter, with reference to Figure 1 Specifically describe the metal foil for a current collector according to the first embodiment of the present invention.

[0042] As Figure 1 shown, the metal foil for a current collector according to the first embodiment of the present invention includes: a first cut portion 10, including a plurality of first cut lines 11 spaced apart along a first direction (for example, the length direction of the metal foil); and a second cut portion 20, including a plurality of second cut lines 21 spaced apart along the first direction (for example, the length direction of the metal foil).

[0043] The first cut portion 10 and the second cut portion 20 are respectively plural, and are alternately spaced apart in parallel along a second direction perpendicular to the first direction (for example, the width direction of the metal foil).

[0044] In this case, the plurality of first cut lines 11 and the plurality of second cut lines 21 are spaced apart in a zigzag arrangement with the ends of each cut line overlapping each other to form an overlapping portion.

[0045] However, the metal foil for a current collector of the present invention should satisfy the following relational expressions 1 and 2. Relational expression 1: Relationship 2:

[0046] In the said relationship, T1 is the thickness of the relevant metal foil, D1 is the separation distance between the adjacent first cut portion and the second cut portion, and L1 is the length of the overlapping portion.

[0047] If the metal foil for the current collector of the present invention does not satisfy Relationship 1 and Relationship 2, it is not only difficult to manufacture the grid-shaped current collector, but also wire breakage will occur, and the active material will be peeled off and fall off during the charge and discharge of the secondary battery due to the low bonding force with the active material.

[0048] The thickness T1 of the metal foil for the current collector of the present invention is not particularly limited. If the thickness of the metal foil is too thin, the operability will be reduced because it is difficult to handle the metal foil during the battery manufacturing process, and the current collecting effect of the manufactured grid-shaped current collector will be negligible. On the other hand, if the thickness of the metal foil is too thick, the thickness of the manufactured grid-shaped current collector will also be thick, thereby increasing the volume and weight. Not only is it difficult to manufacture a high-capacity battery, but also the processability will be reduced when folding the battery cells for assembly. Therefore, the thickness of the metal foil is appropriately in the range of about 6 μm to 30 μm.

[0049] Moreover, in the metal foil for the current collector of the present invention, based on the thickness of the aforesaid metal foil, the separation distance D1 between the adjacent first cut portion 10 and the second cut portion 20 can be in the range of about 75% to 250%. For example, when the thickness of the metal foil is in the range of about 6 μm to 30 μm, the separation distance D1 between the adjacent first cut portion 10 and the second cut portion 20 can be in the range of about 4.5 μm to 75 μm.

[0050] Moreover, in the metal foil for the current collector of the present invention, the lengths of the first cut line 11 and the second cut line 21 are not particularly limited. However, the length of the overlapping ends of the adjacent first cut line 11 and the second cut line 21, that is, the length L1 of the overlapping portions 11a, 21a should be longer than the separation distance D1 between the aforesaid adjacent first cut portion 10 and the second cut portion 20. Specifically, based on the thickness of the aforesaid metal foil, it is preferably adjusted to be in the range of about 100% to 600%. For example, when the thickness of the metal foil is in the range of about 6 μm to 30 μm, the length L1 of the overlapping portions 11a, 21a can be in the range of about 6 μm to 180 μm.

[0051] On the other hand, the metal foil 100 of the present invention is an electrolytic metal foil manufactured by a foil manufacturing process using electroplating. Specifically, one side of the metal foil forms a shiny surface (Shiny surface, "S surface", roller surface) with relatively low roughness and high gloss, and the other side forms a matte surface (Matte surface, "M surface", electrolytic liquid surface) with relatively high roughness and low gloss through a so-called mountain structure.

[0052] The bonding force or processability with the active material can vary depending on the roughness of the matte surface of this metal foil 100. In particular, if the roughness of the matte surface of the metal foil is greater than about 0.5 relative to the thickness of the metal foil 100, wire breakage will occur during processing. Therefore, preferably, the ratio (Rz / T1) of the roughness (Rz) of the matte surface (Matt surface) of the metal foil of the present invention to the thickness T1 of the metal foil is in the range of about 0.1 to 0.5.

[0053] In this case, the tensile strength of the metal foil without forming the first and second cut portions is about 30 kgf / mm 2 at most 90 kgf / mm 2 , specifically, it can be about 30 kgf / mm 2 to 90 kgf / mm 2 , and the elongation rate can be in the range of 2% to 25%.

[0054] The metal of the metal foil of the present invention is not particularly limited as long as it has high conductivity while not inducing chemical changes in the battery. For example, it can be copper, aluminum, nickel, iron, silver, gold, tungsten, tin, platinum, palladium, and their alloys. For example, the metal of the metal foil can be copper (Cu), and the metal foil can be a copper foil, specifically, an electrolytic copper foil.

[0055] <Current collector for battery>

[0056] On the other hand, the present invention provides a current collector for a battery manufactured using the aforementioned metal foil.

[0057] As Figure 2 shown, the current collector for a battery of the present invention is formed by unfolding and stamping the aforementioned metal foil 100, and includes a wire portion 110 and a metal mesh layer 100A formed of a two-dimensional grid structure by a plurality of diamond-shaped opening portions 120.

[0058] In this case, the wire portion 110 satisfies the following relational expressions 3 and 4. Relational expression 3: Relational expression 4:

[0059] In the above formula, T1 is the thickness of the metal mesh layer. For example, it can be in the range of about 6 μm to 30 μm. W1 is the line width of the wire portion. For example, it can be in the range of about 6 μm to 45 μm. P1 is the line pitch of the wire portion, that is, the size of the opening portion. For example, it can be in the range of 6 μm to 45 μm.

[0060] Moreover, the shape of the opening portion 120 is a rhombus, which can better continuously withstand the volume change of the active material compared with other shapes (for example, a circle). This is because when the opening portion is a rhombus, it is easier to move in the length direction and / or the width direction compared with other shapes (for example, a circle).

[0061] The aperture ratio of the current collector for the battery described above is the area ratio occupied by the opening portion 120 based on 100% of the total area of the current collector, and can be about 10% to 300%. Therefore, even if a silicon-based active material is provided in the current collector of the present invention, the volume change of the silicon-based active material can be continuously withstood.

[0062] Although not shown in the figure, the current collector for the battery of the present invention may further include an anti-corrosion layer provided on at least one surface of the metal mesh layer 100A.

[0063] The surface treatment layer can be used to prevent the corrosion of the metal mesh layer 100A, or can be used to strengthen the adhesion, or can be used to reduce the contact resistance.

[0064] In one example, the surface treatment layer can be formed by sputtering, electroplating or electroless plating of any one of metals such as copper, chromium, molybdenum, nickel, tin, zinc (Zn), cobalt (Co), silver (Ag) or their alloys on the metal mesh layer 100A.

[0065] In another example, the surface treatment layer can be formed by chromate treatment of the metal mesh layer 100A with an aqueous solution containing hexavalent chromium ions.

[0066] In still another example, the surface treatment layer can be formed by coating at least one of a silane compound, a nitrogen compound, graphene, a carbon nanotube, and a conductive polymer on the metal mesh layer 100A.

[0067] Among them, the silane compound is not particularly limited as long as it is well-known in the technical field to which the present invention pertains. For example, it can be the following silanes: epoxy-functional silanes such as 3-glycidoxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino-functional silanes such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane; olefin-functional silanes such as vinyltrimethoxysilane, vinylphenyltrimethoxysilane, and vinyltris(2-methoxyethoxy)silane; acrylic-functional silanes such as 3-acryloxypropyltrimethoxysilane; methacrylic-functional silanes such as 3-methacryloxypropyltrimethoxysilane; and mercapto-functional silanes such as 3-mercaptopropyltrimethoxysilane.

[0068] Moreover, the nitrogen compound may include one or more of the commonly known triazole compounds and amine compounds in the technical field to which the present invention pertains. Examples of the triazole compounds include benzotriazole, methylbenzotriazole, carboxybenzotriazole, chlorobenzotriazole, ethylbenzotriazole, and naphthotriazole. Examples of the amine compounds include amide, acrylamide, acetamide, auramine, dodecyltrimethyl ammonium bromide (DTAB), and diethylenetriamine (DETA).

[0069] Moreover, the conductive polymer is not particularly limited. For example, there are polyacetylene, polyaniline (PANI), polyphenylene, polypyrene, polypyrrole, polyphenylene vinyl, polythiophene, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(p-phenylene sulfide) (PPS), etc.

[0070] <Electrode>

[0071] The present invention provides an electrode for a secondary battery including the aforementioned current collector, specifically, a negative electrode for a secondary battery.

[0072] For example, the electrode for a secondary battery (specifically, the negative electrode) of the present invention includes: the aforementioned current collector; and an electrode active material layer (specifically, a negative electrode active material layer) provided on both surfaces of the current collector. The current collector may also selectively include a surface treatment layer provided on at least one surface of the metal mesh layer.

[0073] The description of the current collector is as described above, and its description is omitted herein.

[0074] The above-mentioned negative electrode active material layer contains a negative electrode active material, and may also contain common binders and / or conductive materials known in the technical field to which the present invention pertains.

[0075] The negative electrode active material can be a compound capable of achieving ion intercalation and deintercalation without limitation. Non-limiting examples of the negative electrode active material that can be used include carbon-based and silicon-based positive electrode active materials. In addition, lithium metal or its alloy, other metal oxides such as TiO2, SnO2, and Li4Ti5O that can occlude and release lithium and have a potential for lithium less than 2V can also be used. 12 and the like.

[0076] The method of manufacturing an electrode for a secondary battery using the aforementioned current collector is self-evident to those of ordinary skill in the technical field to which the present invention pertains, and a detailed description thereof is omitted herein.

[0077] <Secondary Battery>

[0078] The present invention provides a secondary battery including the aforementioned negative electrode.

[0079] The secondary battery may be a lithium secondary battery. Specifically, it may be a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, a lithium ion polymer secondary battery, or the like.

[0080] For example, the lithium secondary battery includes: a positive electrode containing a positive electrode active material; a negative electrode containing a negative electrode active material; and an electrolyte loaded between the positive electrode and the negative electrode. And it may also include a separator.

[0081] The lithium secondary battery of the present invention can be manufactured according to the common methods known in the technical field to which the present invention pertains. For example, after inserting a separator between the negative electrode and the positive electrode, an electrolyte added with the aforementioned electrolyte additive can be put in for manufacturing.

[0082] Among them, the positive electrode is not particularly limited, and a positive electrode commonly known in the technical field to which the present invention pertains can be used.

[0083] And the electrolyte may include: common lithium salts known in the technical field to which the present invention pertains; and an electrolyte solvent.

[0084] And the separator can be a porous separator. For example, polypropylene-based, polyethylene-based, polyolefin-based porous separators can be used, or an organic / inorganic composite separator containing an inorganic substance can be used.

[0085] Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are only for illustrating the present invention, and the present invention is not limited to the following examples.

[0086] [Examples 1 to 21 and Comparative Examples 1 to 54]

[0087] In a copper foil (thickness: 20 μm), a plurality of cut lines are formed by forming scabbards arranged in a zigzag pattern. In this case, by adjusting the separation distance D1 between adjacent cut lines and the overlapping portion length L1 between the ends of each cut line, the line width and line pitch of the wire portion in the current collector are as shown in Tables 1 and 2 below.

[0088] Then, a force of 1 kgf / cm is applied in the width direction to the copper foil formed with a plurality of cut lines to expand it. After forming a wire portion and a plurality of diamond-shaped openings, it is rolled by a roll press (pressure: about 10 kgf / mm 2 ) to manufacture current collectors for batteries of Examples 1 to 21 and Comparative Examples 1 to 54.

[0089] [Experimental Example 1]

[0090] In order to confirm whether a grid-shaped current collector can be manufactured according to the present invention based on the separation distance (line width of the wire portion) D1 between adjacent cut lines and the overlapping portion length (line pitch of the wire portion) L1 between the ends of each cut line in comparison with the thickness of the copper foil, and whether the active material peels off (falls off), the evaluation is carried out in the following manner, and the results are shown in Tables 1 and 2 below, respectively.

[0091] (1) Prepare the sample

[0092] Samples are prepared by coating the negative electrode active material on both sides of the current collectors for batteries of Examples 1 to 21 and Comparative Examples 1 to Comparative Examples 54 with a thickness of 100 μm. In this case, artificial graphite, styrene butadiene rubber (SBR), and carboxymethylcellulose (CMC) are mixed in a weight ratio of 96:2:2 in pure water to prepare the negative electrode active material.

[0093] (2) Whether the active material falls off

[0094] As Figure 3 shown, after placing the sample S on a metal bar (diameter: 10 mm) 1, a 1 kg weight 2 is suspended at the lower end of the sample S for about 1 minute, and then it is observed whether the active material peels off and falls off from the current collector. In this case, if the active material does not peel off, it is indicated as "No (No)", and if it peels off, it is indicated as "falls off".

[0095] (3) Whether the wire breaks

[0096] After manufacturing batteries using each sample, it is observed visually and under a 50-fold microscope whether there is a wire breakage inside the battery.

[0097] [Table 1]

[0098] [Table 2]

[0099] [Experimental Example 2: Evaluation of Physical Properties of Metal Foil]

[0100] In order to confirm the changes in the physical properties of the metal foil for the current collector of the present invention with the changes in the thickness of the metal foil, the matte surface roughness of the metal foil, and their ratios, the physical properties of the following Samples 1A to 2C and Comparative Samples 1A to 2C were evaluated by the following method, and the results are shown in Table 3 below.

[0101] (1) Prepare the sample

[0102] Using the copper foil used in Example 1, except that the thickness and matte surface roughness of the copper foil were adjusted as shown in Table 3 below, Samples 1A to 2C and Comparative Samples 1A to 2C were respectively manufactured in the same manner as in Example 1.

[0103] (2) Thickness

[0104] The thickness of the metal foil was measured by the unit area weight method (IPC-TM-650 2.2.12).

[0105] (3) Surface roughness

[0106] The M-surface roughness of the metal foil was measured by a shape measuring instrument (MarSurf, model: M 300C portable roughness measuring instrument (Mobile roughness measuring instrument)) according to the Rz standard (IPC-TM-650 2.2.17).

[0107] (4) Elongation and tensile strength

[0108] The tensile strength (MPa) and elongation (%) of the metal foil were measured by a UTM (Instron, model: 5942) according to the IPC-TM-650 2.4.18 standard.

[0109] (5) Processability

[0110] During the process of manufacturing the metal foil for the current collector, when a force of about 1 kgf / cm 2 was applied to the copper foil, it was visually confirmed whether the shape of the scabbard formed a rhombus shape.

[0111] [Table 3]

Claims

1. A metal foil for a current collector, characterized in that: It includes: A first cut portion, including a plurality of first cut lines formed at intervals along a first direction; and A second cut portion, including a plurality of second cut lines formed at intervals along the first direction, The first cut portion and the second cut portion are each plural, and are alternately arranged in parallel at intervals in a second direction perpendicular to the first direction, The plurality of first cut lines and the plurality of second cut lines are arranged in a zigzag pattern such that the ends of the respective cut lines overlap each other to form an overlapping portion, Satisfying the following relational expressions 1 and 2, Relationship 1: Relationship 2: In the relational expressions, T1 is the thickness of the relevant metal foil, D1 is the separation distance between adjacent first cut portions and second cut portions, and L1 is the length of the overlapping portion.

2. The metal foil for a current collector according to claim 1, wherein The ratio of the surface roughness Rz of the metal foil to the thickness T1 of the relevant metal foil is in the range of 0.1 to 0.

5.

3. The metal foil for a current collector according to claim 2, characterized in that, The metal foil that does not form the first cut portion and the second cut portion has a tensile strength of 30 kgf / mm 2 to 90 kgf / mm 2 and an elongation rate in the range of 2% to 25%.

4. The metal foil for a current collector according to claim 1, characterized in that, It has a thickness in the range of 6 μm to 30 μm.

5. The metal foil for a current collector according to claim 1, wherein The metal of the relevant metal foil is selected from the group consisting of copper, aluminum, nickel, iron, silver, gold, tungsten, tin, platinum, palladium, and their alloys.

6. A current collector for a battery, characterized in that: It includes a metal grid layer, formed by stamping after unfolding the metal foil according to any one of claims 1 to 5, and composed of a wire portion and a rhombus-shaped opening portion, The wire portion satisfies the following relational expressions 3 and 4, Relationship 3: Relationship 4: In the relational expressions, T1 is the thickness of the metal grid layer, W1 is the wire width of the wire portion, and P1 is the wire pitch of the wire portion.

7. The current collector for a battery according to claim 6, characterized in that, The porosity is 10% to 300%.

8. The current collector for a battery according to claim 1, characterized in that, It further includes a surface treatment layer provided on at least one surface of the metal grid layer.

9. An electrode for a secondary battery, characterized in that, It includes: The current collector according to claim 6; And An active material layer, provided on both surfaces of the current collector.

10. The electrode for a secondary battery according to claim 9, wherein, The current collector further includes a surface treatment layer provided on at least one surface of the metal grid layer.

11. The secondary battery electrode according to claim 9, wherein The active material layer contains a silicon-based active material.

12. A secondary battery, characterized in that, It includes the secondary battery electrode according to claim 9.

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