JP6700347B2 - Copper foil with minimal sagging and tearing, electrode including the same, secondary battery including the same, and manufacturing method thereof - Google Patents

Description

  The present invention relates to a copper foil with minimal sagging and tearing, an electrode including the same, a secondary battery including the same, and a method for manufacturing the same.

  Copper foil is used to manufacture various products such as a negative electrode for a secondary battery and a flexible printed circuit board (FPCB).

  Among these, the copper foil manufactured by electroplating is also called an electrolytic copper foil. Such an electrolytic copper foil is generally manufactured by a roll-to-roll (RTR) process, a negative electrode of a secondary battery by a roll-to-roll (RTR) process, a flexible printed circuit board (FPCB), etc. Used in the manufacture of. The roll-to-roll (RTR) process is known to be suitable for mass production of products because continuous production is possible. However, when the copper foil is broken, torn or bagging occurs during the roll-to-roll (RTR) process, the operation of the roll-to-roll process equipment is interrupted and the problem that has occurred is solved. After that, the equipment must be restarted, which reduces productivity.

  In particular, when sagging or tearing occurs in the copper foil during the process of manufacturing the secondary battery using the copper foil, stable product production becomes difficult. As described above, the sagging or tearing of the copper foil generated in the manufacturing process of the secondary battery lowers the manufacturing yield of the secondary battery and increases the manufacturing cost of the product.

  Among the causes of slack and tearing that occur in the secondary battery manufacturing process, a method of controlling the weight deviation of the copper foil to a low level is known as a method of solving the cause of the copper foil. However, there is a limit to solving the problems of sagging and tearing that occur in the manufacturing process of the secondary battery, only by controlling the weight deviation of the copper foil. In particular, in recent years, in order to increase the capacity of secondary batteries, an ultra-thin copper foil, for example, a copper foil having a thickness of 8 μm or less, is increasingly used as a negative electrode current collector. In this case, even if the weight deviation of the copper foil is precisely controlled, sagging and tearing defects are intermittently generated in the secondary battery manufacturing process. Therefore, it is necessary to prevent or suppress the occurrence of sagging or tearing of the copper foil in the manufacturing process of the secondary battery.

  The present invention intends to provide a copper foil, an electrode including the same, a secondary battery including the same, and a method for manufacturing the same, which can solve such problems.

  One embodiment of the present invention seeks to provide a copper foil with minimal sagging or tearing. One embodiment of the present invention is a copper foil having an excellent roll-to-roll (RTR) processability by preventing the occurrence of sagging or tearing in the manufacturing process of a secondary battery, even if it has a small thickness. Try to provide.

  Another embodiment of the present invention is to provide a secondary battery electrode including such a copper foil and a secondary battery including such a secondary battery electrode.

  Yet another embodiment of the present invention seeks to provide a flexible copper foil laminated film containing such a copper foil.

  Yet another embodiment of the present invention seeks to provide a method of manufacturing a copper foil capable of preventing the occurrence of sagging or tearing during the manufacturing process.

  In addition to the aspects of the invention described above, other features and advantages of the invention will be described hereinafter or will be apparent to those having ordinary skill in the art to which the invention pertains. Will.

In order to solve such a problem, an embodiment of the present invention includes a copper layer and an anticorrosive film disposed on the copper layer, and has a PAR (Peak to Arithmetic Mean Roughness) of 0.8 to 12.5. ), a copper foil having a tensile strength of 29 to 58 kgf/mm ² and a weight deviation of 3% or less. Here, the PAR is calculated by the following equation 1.

(Equation 1)
PAR=Rp/Ra

  In the above formula 1, Rp is a maximum profile peak height, and Ra is an arithmetic mean roughness.

  The copper foil may have a (220) plane, and the collective tissue coefficient [TC(220)] of the (220) plane may be 0.49 to 1.28.

  The rust preventive layer may include at least one of chromium (Cr), a silane compound and a nitrogen compound.

  The copper foil may have a thickness of 4 μm to 30 μm.

  Another embodiment of the present invention provides a secondary battery electrode including the copper foil and an active material layer disposed on the copper foil.

  Yet another embodiment of the present invention provides a positive electrode, a negative electrode facing the positive electrode, and an environment in which ions can move, the positive electrode being disposed between the positive electrode and the negative electrode. A secondary battery including an electrolyte to be provided and a separator that electrically insulates the positive electrode and the negative electrode, the negative electrode including the copper foil and an active material layer disposed on the copper foil. I will provide a.

  Yet another embodiment of the present invention provides a flexible copper foil laminated film including a polymer film and the copper foil disposed on the polymer film.

According to another embodiment of the present invention, a positive electrode plate and a rotating negative electrode drum, which are spaced apart from each other in an electrolytic solution containing copper ions, are energized at a current density of 40 to 80 A/dm ² to form a copper layer. The electrolytic solution includes 70 to 90 g/L of copper ions, 50 to 150 g/L of sulfuric acid, 2 to 20 mg/L of 1-phenyl-5-mercapto-1H-tetrazole (1-Phenyl-5). -Mercapto-1H-tetrazole) and a method for producing a copper foil containing 2 to 20 mg/L of polyethylene glycol (PEG).

  The electrolytic solution may include silver (Ag) in an amount of 50 mg/L or less.

  Before the step of forming the copper layer, the step of polishing the surface of the rotating negative electrode drum with a brush having a grain size of #800 to #3000 may be included.

The electrolyte may have a flow rate of 39 to 46 m ³ /hour.

  The flow rate deviation per unit time (second, second) may be 5% or less.

  The general description of the present invention is merely for the purpose of illustrating or explaining the present invention, and does not limit the scope of rights of the present invention.

  The copper foil according to one embodiment of the present invention has excellent resistance to sagging or tearing. Therefore, according to one embodiment of the present invention, the occurrence of slack or tear during the manufacturing process of the copper foil or the manufacturing process of the secondary battery using the copper foil is prevented. As described above, the copper foil according to the embodiment of the present invention has excellent roll-to-roll (RTR) processability.

  In addition, according to another embodiment of the present invention, it is possible to manufacture an electrode for a secondary battery in which sagging or tearing is prevented or minimized.

The accompanying drawings are formed to form a part of this specification to facilitate the understanding of the present invention, illustrate the embodiments of the present invention, and explain the principle of the present invention together with the detailed description of the invention.
1 is a schematic sectional view of a copper foil according to an embodiment of the present invention. It is a figure which shows the XRD graph of copper foil. FIG. 6 is a schematic cross-sectional view of a copper foil according to another embodiment of the present invention. FIG. 7 is a schematic cross-sectional view of an electrode for a secondary battery according to still another embodiment of the present invention. FIG. 7 is a schematic cross-sectional view of an electrode for a secondary battery according to still another embodiment of the present invention. FIG. 7 is a schematic cross-sectional view of a secondary battery according to still another embodiment of the present invention. FIG. 6 is a cross-sectional view of a flexible copper foil laminated film according to still another embodiment of the present invention. It is a schematic diagram which shows the manufacturing process of the copper foil shown in FIG. It is a photograph showing a state in which sagging (bagginess) is generated in the copper foil. It is a photograph showing a state where the copper foil is torn.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  It will be apparent to those skilled in the art that various modifications and variations of the present invention can be made without departing from the technical idea and scope of the present invention. Therefore, the present invention includes all modifications and variations within the scope of the invention described in the claims and equivalents thereof.

  The shapes, dimensions, ratios, angles, numbers, etc. disclosed in the drawings for describing the embodiments of the present invention are mere examples, and the present invention is not limited to the matters shown in the drawings. Like components are referred to by like reference numerals throughout the specification.

  When the terms “include”, “have”, “consist”, etc. are used in this specification, other parts may be added unless the expression “only” is used. When a component is expressed in the singular, the plural is included unless otherwise specified. Further, in the interpretation of the constituent elements, it is construed that the error range is included even if not explicitly stated otherwise.

  In the case of the explanation of the positional relationship, for example, the positional relationship between the two parts is explained, such as'up above','upper part of','lower part of','next to', etc. In some cases, there may be one or more other parts between the two parts, unless the expressions'immediately' or'directly' are used.

  In the case of an explanation of a temporal relationship, for example, when a temporal predecessor relationship is explained, such as'after','followed by','next to','before', etc. Unless the expression "immediately" or "directly" is used, it may include a case where it is not continuous.

  The terms'first','second', etc. are used to describe various components, but these components are not limited to such terms. Such terms are only used to distinguish one element from another. Therefore, the first component referred to below may be the second component within the technical idea of the present invention.

  The term "at least one" should be understood to include all combinations that can be presented from one or more related items.

  The respective features of the many embodiments of the present invention can be combined or combined with each other in part or in whole, and various technically various interlocking and driving are possible, and the respective embodiments can be independent of each other. It can be carried out or together in an associative relationship.

  FIG. 1 is a schematic sectional view of a copper foil 100 according to an embodiment of the present invention.

  Referring to FIG. 1, the copper foil 100 includes a copper layer 110 and a rust preventive film 210 disposed on the copper layer 110.

  According to one embodiment of the present invention, the copper layer 110 has a matte surface MS and an opposite shiny surface SS.

  The copper layer 110 can be formed on the rotating negative electrode drum, for example, by electroplating (see FIG. 8). Here, the shiny surface SS refers to the surface that comes into contact with the rotating negative electrode drum during the electroplating process, and the matte surface MS refers to the side surface opposite to the shiny surface SS.

  Although the shiny surface SS generally has a lower surface roughness (Rz) than the matte surface MS, one embodiment of the present invention is not limited thereto. The surface roughness (Rz) of the shiny surface SS may be the same as or higher than the surface roughness (Rz) of the matte surface MS.

  The rust preventive film 210 may be disposed on at least one of the matte surface MS and the shiny surface SS of the copper layer 110. Referring to FIG. 1, a rust preventive film 210 is disposed on the mat surface MS. However, the embodiment of the present invention is not limited to this, and the anticorrosive film 210 may be disposed only on the shiny surface SS, or may be disposed on both the mat surface MS and the shiny surface SS. it can.

  The anticorrosion film 210 protects the copper layer 110. The anti-corrosion film 210 may prevent the copper layer 110 from being oxidized or deteriorated during the storage process. Therefore, the rust preventive film 210 is also referred to as a protective layer. The rust preventive film 210 is not particularly limited, and any film or layer capable of protecting the copper layer 110 can be the rust preventive film 210.

  According to an embodiment of the present invention, the rust preventive film 210 may include at least one of chromium (Cr), a silane compound, and a nitrogen compound.

  For example, the rustproof film 210 can be formed with a rustproofing solution containing chromium (Cr), that is, a rustproofing solution containing a chromic acid compound.

  According to one embodiment of the present invention, the copper foil 100 has a first surface S1 that is a surface in the mat surface MS direction and a second surface S2 that is a surface in the shiny surface SS direction with respect to the copper layer 110. In FIG. 1, the first surface S1 of the copper foil 100 is the surface of the rust preventive film 210, and the second surface S2 is the shiny surface SS.

  According to an embodiment of the present invention, the copper foil 100 has a PAR (Peak to Arithmetic Mean Roughness) of 0.8 to 12.5.

  Here, the PAR can be calculated by the following equation 1.

(Equation 1)
PAR=Rp/Ra

  In Equation 1, Rp is the maximum profile peak height and Ra is the arithmetic mean roughness.

  Rp and Ra can be measured with a roughness meter according to JIS B 0601-2001 standard. Specifically, according to one embodiment of the present invention, Rp and Ra can be measured with the SJ-310 model of Mitutoyo Corporation. In the Rp and Ra measurement using the SJ-310 model of Mitutoyo, the measurement length excluding the cutoff length is 4 mm, and the cutoff length is 0.8 mm at the initial and final stages, respectively. The radius of the stylus tip is 2 μm and the measurement pressure is 0.75 mN. After the above setting, the Rp and Ra values can be obtained by the measurement, which are the Rp and Ra based on the measured value by the Mitutoyo roughness meter. For the evaluation of physical properties, Rp and Ra are repeatedly measured three times each and the arithmetic mean value thereof is used.

  If the PAR of the copper foil 100 exceeds 12.5, when the copper foil 100 is wound on a roll, a winder or a bobbin in the manufacturing process of the copper foil 100, air is trapped between the copper foils. Bagging may occur.

  On the other hand, if the PAR of the copper foil 100 is less than 0.8, during the production of the copper foil 100 by the roll-to-roll process, when the copper foil 100 is wound up, it is between the copper foil and the copper foil. Weight superposition easily occurs, and as the winding length becomes longer, the copper foil 100 may locally increase and a sagging defect may occur.

  FIG. 9 is a photograph showing a state in which the copper foil has sagging. In FIG. 9, the portion indicated by the arrow (↑) is the portion where the slack has occurred. According to an embodiment of the present invention, the slack refers to a state in which the copper foil 100 is flat and not spread, or a portion thereof. In some cases, bagging is also called wrinkle.

According to one embodiment of the present invention, the copper foil 100 has a tensile strength of 29 to 58 kgf/mm ² . The tensile strength can be measured by a universal tester (UTM) according to the regulations of IPC-TM-650 Test Method Manual. According to one embodiment of the present invention, tensile strength can be measured with an Instron universal tester. Here, the width of the tensile strength measurement sample is 12.7 mm, the distance between the grips is 50 mm, and the measurement speed is 50 mm/min.

  To evaluate the physical properties, the tensile strength of the sample is repeatedly measured three times, and the average value is used as the tensile strength of the copper foil 100.

If the tensile strength of the copper foil 100 is less than 29 kgf/mm ² , a slack defect due to plastic deformation may occur during winding of the copper foil 100. On the other hand, when the tensile strength of the copper foil 100 exceeds 58 kgf/mm ² , the phenomenon of sagging or wrinkling can be reduced, but the brittleness of the copper foil 100 itself increases and the usability of the copper foil 100 decreases. .. For example, a tear may occur in a manufacturing process of a copper foil or a manufacturing process of an electrode for a secondary battery using the copper foil, which may cause difficulty in manufacturing a stable product.

  FIG. 10 is a photograph showing a state where the copper foil is torn. For example, if such tearing occurs during the copper foil manufacturing process by the roll-to-roll process, the operation of the roll-to-roll process equipment must be interrupted, the torn portion must be removed, and the process equipment must be restarted. I have to. In this case, the process time and cost increase, and the productivity decreases.

  According to one embodiment of the present invention, the copper foil 100 has a weight deviation of 3% or less. More specifically, the copper foil 100 can have a weight deviation of 0-3%. Here, the weight deviation of 0 means that there is no weight deviation.

  According to one embodiment of the present invention, the weight deviation can be obtained from the average (average weight) of the weights measured at three arbitrary points in the width direction of the copper foil 100 and the standard deviation of the weights. Specifically, after each of 5 cm×5 cm samples was taken at three points arranged along the width direction of the copper foil 100, that is, a direction (Transverse Direction, TD) perpendicular to the winding direction, each was taken. Measure the weight of the sample to calculate the weight per unit area, calculate the “average weight” and “standard deviation of weight” at three points from the weight per unit area of three samples, and then calculate the weight deviation by Equation 2. be able to.

  If the weight deviation of the copper foil 100 exceeds 3%, when the copper foil 100 is wound in a roll-to-roll process, the copper foil 100 is locally stretched due to a tension applied to the copper foil 100 or a weight superposition. Slack may occur at 100. Therefore, according to an embodiment of the present invention, the weight deviation of the copper foil 100 is reduced to 3% or less.

  According to one embodiment of the present invention, the copper foil 100 has a (220) plane, and the collective composition coefficient [TC(220)] of the (220) plane is 0.49 to 1.28. The collective tissue coefficient [TC(220)] relates to the crystal structure of the surface of the copper foil 100.

  Hereinafter, a method for measuring and calculating the collective composition coefficient [TC(220)] of the (220) plane of the copper foil 100 according to an embodiment of the present invention will be described with reference to FIG.

  FIG. 2 is a diagram showing an XRD graph of copper foil. More specifically, FIG. 2 is an XRD graph of the copper layer 110 that constitutes the copper foil 100.

  In order to measure the collective tissue coefficient [TC(220)] of the (220) plane, first, n crystals were measured by the X-ray diffraction method (XRD) in the range of the diffraction angle (2θ) of 30° to 95°. An XRD graph having peaks corresponding to the planes is obtained [Target: Copper K alpha 1,2θ interval: 0.01°, 2θ scan speed: 3°/min]. For example, as shown in FIG. 2, an XRD graph showing peaks corresponding to the (111) plane, the (200) plane, the (220) plane, and the (311) plane can be obtained. Referring to FIG. 2, n is 4.

Then, the XRD diffraction intensity [I(hkl)] of each crystal plane (hkl) is obtained from this graph. Further, the XRD diffraction intensity [I ₀ (hkl)] for each of the n crystal faces of the standard copper powder defined by JCPDS (Joint Committee on Powder Diffraction Standards) is determined. Then, the arithmetic mean value for “I(hkl)/I ₀ (hkl)” of n crystal planes is calculated, and I(220)/I ₀ (220) of the (220) plane is divided by the arithmetic mean value. By doing so, the collective organization coefficient [TC(220)] of the (220) plane is calculated. That is, the collective organization coefficient [TC(220)] of the (220) plane is calculated by the following Expression 3.

  According to one embodiment of the present invention, the (220) plane of each of the first and second surfaces S1 and S2 of the copper foil 100 has a collective composition coefficient [TC(220)] of 0.49 to 1.28. Can have. More specifically, the (220) plane of the copper layer 110 may have a collective tissue coefficient [TC(220)] of 0.49 to 1.28. It means that the higher the collective composition coefficient [TC(220)] of the (220) plane, the more dense the crystal structure of the copper foil 100.

  When the collective composition coefficient [TC(220)] of the (220) plane is less than 0.49, the crystal structure of the copper foil 100 is not dense and the copper foil 100 is wound on a roll, winder or bobbin. The possibility that the organization is easily deformed and the copper foil 100 is slackened increases. If the coefficient of the collective composition of the (220) plane exceeds 1.28, the composition of the copper foil 100 becomes too dense and brittle, and the manufacturing process of the copper foil 100 or a product using the copper foil 100 Since the copper foil 100 is torn in the manufacturing process of 1., it may be difficult to produce a stable product.

  According to one embodiment of the present invention, the copper foil 100 may have a thickness of 4 μm to 30 μm. When the thickness of the copper foil 100 is less than 4 μm, workability is deteriorated in the manufacturing process of the copper foil 100 or a product using the copper foil 100, for example, a manufacturing process of a secondary battery electrode or a secondary battery. When the thickness of the copper foil 100 exceeds 30 μm, the thickness of the secondary battery electrode using the copper foil 100 becomes large, and such a large thickness causes difficulty in realizing a high capacity secondary battery. Sometimes.

  FIG. 3 is a schematic sectional view of a copper foil 200 according to another embodiment of the present invention. Hereinafter, in order to avoid duplication, description of the components described above will be omitted.

  Referring to FIG. 3, a copper foil 200 according to another embodiment of the present invention includes a copper layer 110 and two rust preventive films 210 and 220 disposed on a mat surface MS and a shiny surface SS of the copper layer 110, respectively. Including. Compared to the copper foil 100 shown in FIG. 1, the copper foil 200 shown in FIG. 3 further includes a rust preventive film 220 disposed on the shiny surface SS of the copper layer 110.

  For convenience of description, of the two anticorrosion films 210 and 220, the anticorrosion film 210 disposed on the mat surface MS of the copper layer 110 is the first protection layer and the anticorrosion film 220 disposed on the shiny surface SS. Is referred to as a second protective layer.

  Further, the first surface S1 of the copper foil 200 shown in FIG. 3 is the same as the surface of the rust preventive film 210 arranged on the mat surface MS, and the second surface S2 is the rust preventive film 220 arranged on the shiny surface SS. Is the same as the surface of.

  According to another embodiment of the present invention, the two anticorrosive films 210 and 220 may each include at least one of chromium (Cr), a silane compound and a nitrogen compound.

The copper foil 200 shown in FIG. 3 has a PAR (Peak to Arithmetic Mean Roughness) of 0.8 to 12.5, a tensile strength of 29 to 58 kgf/mm ² and a weight deviation of 3% or less.

  Further, the (220) plane of the copper foil 200 has a collective composition coefficient [TC(220)] of 0.49 to 1.28. More specifically, the (220) plane of the copper layer 110 forming the copper foil 200 has a collective composition coefficient [TC(220)] of 0.49 to 1.28.

  The copper foil 200 shown in FIG. 3 has a thickness of 4 μm to 30 μm.

  FIG. 4 is a schematic cross-sectional view of a secondary battery electrode 300 according to still another embodiment of the present invention.

  The secondary battery electrode 300 shown in FIG. 4 can be applied to the secondary battery 500 shown in FIG. 6, for example.

  Referring to FIG. 4, an electrode 300 for a secondary battery according to another embodiment of the present invention includes a copper foil 100 and an active material layer 310 disposed on the copper foil 100. Here, the copper foil 100 is used as a current collector.

  More specifically, an electrode 300 for a secondary battery according to still another embodiment of the present invention is a copper foil 100 having a first surface S1 and a second surface S2, and a first surface S1 and a second surface of the copper foil 100. The active material layer 310 arranged on at least one of S2 is included. The copper foil 100 also includes a copper layer 110 and a rustproof film 210 disposed on the copper layer 110.

  FIG. 4 shows the current collector using the copper foil 100 of FIG. However, another embodiment of the present invention is not limited to this, and the copper foil 200 shown in FIG. 3 can be used as a collector of the secondary battery electrode 300.

  Further, the structure in which the active material layer 310 is arranged only on the first surface S1 of the surfaces S1 and S2 of the copper foil 100 is shown in FIG. 4, but another embodiment of the present invention is not limited thereto. It is not something that will be done. The active material layer 310 may be disposed on both the first surface S1 and the second surface S2 of the copper foil 100, or the active material layer 310 may be disposed only on the second surface S2 of the copper foil 100. .

  The active material layer 310 shown in FIG. 4 is made of an electrode active material, and in particular, may be made of a negative electrode active material. That is, the secondary battery electrode 300 shown in FIG. 4 can be used as a negative electrode.

  The active material layer 310 may include at least one of carbon, metal, metal oxide, and metal-carbon composite. As the metal, at least one kind of Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe can be used. In addition, the active material layer 310 may include silicon (Si) to increase the charge/discharge capacity of the secondary battery.

  When the copper foil 100 according to the embodiment of the present invention is used, tearing or sagging of the copper foil 100 is prevented during the manufacturing process of the secondary battery electrode 300. Therefore, the manufacturing efficiency of the secondary battery electrode 300 can be improved, and the charging/discharging efficiency and the capacity retention rate of the secondary battery including the secondary battery electrode 300 can be improved.

  FIG. 5 is a schematic sectional view of a secondary battery electrode 400 according to another embodiment of the present invention.

  The secondary battery electrode 400 according to another embodiment of the present invention includes a copper foil 200 and active material layers 310 and 320 disposed on the copper foil 200.

  Referring to FIG. 5, the copper foil 200 includes a copper layer 110 and two rust preventive films 210 and 220 disposed on both surfaces MS and SS of the copper layer 110. In addition, the secondary battery electrode 300 shown in FIG. 5 includes two active material layers 310 and 320 disposed on both surfaces of the copper foil 200. Here, the active material layer 310 disposed on the first surface S1 of the copper foil 200 is the first active material layer, and the active material layer 320 disposed on the second surface S2 of the copper foil 200 is the second active material layer. Say

  The two active material layers 310 and 320 may be formed of the same material by the same method, or may be formed by different materials or different methods.

  FIG. 6 is a schematic cross-sectional view of a secondary battery 500 according to still another embodiment of the present invention. The secondary battery 500 shown in FIG. 6 is, for example, a lithium secondary battery.

  Referring to FIG. 6, a secondary battery 500 includes a cathode 370, a negative electrode 340 facing the positive electrode 370, and a positive electrode 370 and a negative electrode 340. An electrolyte 350 that provides an environment in which the positive electrode 370 and the negative electrode 340 are electrically insulated from each other is included. Here, the ions that move between the positive electrode 370 and the negative electrode 340 are lithium ions. The separation film 360 separates the positive electrode 370 and the negative electrode 340 in order to prevent the charge generated at one electrode from moving to another electrode through the inside of the secondary battery 500 and wasting it. Referring to FIG. 6, the separation membrane 360 is disposed inside the electrolyte 350.

  The positive electrode 370 includes a positive electrode current collector 371 and a positive electrode active material layer 372. As the positive electrode current collector 371, for example, an aluminum foil can be used.

  The negative electrode 340 includes a negative electrode current collector 341 and an active material layer 342. The active material layer 342 of the negative electrode 340 includes a negative electrode active material.

  As the negative electrode current collector 341, the copper foils 100 and 200 shown in FIGS. 1 and 3 can be used. Further, the secondary battery electrodes 300 and 400 shown in FIGS. 4 and 5 can be used as the negative electrode 340 of the secondary battery 500 shown in FIG.

  FIG. 7 is a schematic sectional view of a flexible copper foil laminated film 600 according to still another embodiment of the present invention.

  A soft copper foil laminated film 600 according to another embodiment of the present invention includes a polymer film 410 and a copper foil 100 disposed on the polymer film 410. A soft copper foil laminated film 600 including the copper foil 100 shown in FIG. 1 is shown in FIG. 7, but another embodiment of the present invention is not limited thereto. For example, the copper foil 200 shown in FIG. 3 or another copper foil can be used for the flexible copper foil laminated film 600.

  The polymer film 410 has flexibility and non-conductivity. There is no particular limitation on the type of polymer film 410. The polymer film 410 may include polyimide, for example. The flexible copper foil laminated film 600 may be formed by laminating the polyimide film and the copper foil 100 with a roll press. Alternatively, the flexible copper foil laminated film 600 can be prepared by coating the polyimide precursor solution on the copper foil 100 and then heat-treating it.

  The copper foil 100 includes a copper layer 110 having a matte surface MS and a shiny surface SS, and a rust preventive film 210 disposed on at least one of the matte surface MS and the shiny surface SS of the copper layer 110. Here, the rust preventive film 210 may be omitted.

  Referring to FIG. 7, the polymer film 410 is disposed on the anticorrosion film 210, but another embodiment of the present invention is not limited thereto. The polymer film 410 may be disposed on the shiny surface SS of the copper layer 110.

  Hereinafter, a method of manufacturing the copper foil 200 according to another embodiment of the present invention will be described in detail with reference to FIG.

  FIG. 8 is a schematic view showing a method for manufacturing the copper foil 200 shown in FIG.

First, the positive electrode plate 13 and the rotating negative electrode drum 12 which are arranged apart from each other in the electrolytic solution 11 containing copper ions are energized at a current density of 40 to 80 ASD (A/dm ² ) to form the copper layer 110.

Specifically, referring to FIG. 8, the positive electrode plate 13 and the rotating negative electrode drum 12 arranged in the electrolytic solution 11 housed in the electrolytic cell 10 are energized at a current density of 40 to 80 ASD (A/dm ² ). The copper layer 110 is formed on the rotating negative electrode drum 12 by electrodepositing copper. At this time, the distance between the positive electrode plate 13 and the rotating negative electrode drum 12 can be adjusted within the range of 8 to 13 mm.

  The higher the current density applied between the positive electrode plate 13 and the rotating negative electrode drum 12 is, the more uniform the plating is and the less the surface roughness of the matte surface MS of the copper layer 110 is. The surface roughness of the matte surface MS of the copper layer 110 is increased.

  The electrolytic solution 11 contains 70 to 90 g/L of copper ions and 50 to 150 g/L of sulfuric acid. In the electrolytic solution 11 having such concentration, copper can be easily electrodeposited on the rotating negative electrode drum 12.

  In addition, the electrolytic solution 11 includes 2 to 20 mg/L of 1-phenyl-5-mercapto-1H-tetrazole (1-Phenyl-5-mercapto-1H-tetrazole) and 2 to 20 mg/L of polyethylene glycol (PEG). ..

  1-Phenyl-5-mercapto-1H-tetrazole (1-Phenyl-5-mercapto-1H-tetrazole) is also abbreviated as “PMT” and can be represented by the following chemical formula 1.

The tensile strength of the copper foil 200 can be adjusted by adjusting the concentration of 1-phenyl-5-mercapto-1H-tetrazole (PMT). In order to adjust the tensile strength of the copper foil 200 within the range of 29 to 58 kgf/mm ² , the concentration of 1-phenyl-5-mercapto-1H-tetrazole is adjusted within the range of 2 to 20 mg/L. When the concentration of 1-phenyl-5-mercapto-1H-tetrazole is less than 2 mg/L, the tensile strength of the copper foil 200 may decrease to less than 29 kgf/mm ² . On the other hand, when the concentration of 1-phenyl-5-mercapto-1H-tetrazole exceeds 20 mg/L, the tensile strength of the copper foil 200 may exceed 58 kgf/mm ² .

  Polyethylene glycol (PEG) acts as a brightening agent in the electrolytic solution 11.

  If the concentration of polyethylene glycol (PEG) exceeds 20 mg/L and is excessively high, the collective composition of the (220) plane of the copper foil 200 develops and the collective composition coefficient of the (220) plane [TC (220)]. Will exceed 1.28. On the other hand, when the concentration of polyethylene glycol (PEG) is less than 2 mg/L, the collective tissue coefficient [TC(220)] of the (220) plane of the copper foil 200 is less than 0.49. Therefore, in order to set the texture coefficient [TC(220)] of the (220) plane of the copper foil 200 in the range of 0.49 to 1.28, the concentration of polyethylene glycol (PEG) is 2 to 20 mg/. Adjust to L range.

  The electrolytic solution 11 contains 50 mg/L or less of silver (Ag). Here, silver (Ag) includes an ionic state (Ag+) dissociated in the electrolytic solution 11 and a state (Ag) not dissociated in the electrolytic solution 11, and includes all states existing as a salt.

  According to another embodiment of the present invention, as the concentration of silver (Ag) decreases, the PAR (Peak to Arithmetic Mean Roughness) of the copper foil 200 increases.

  Generally, silver (Ag) in the electrolytic solution 11 corresponds to impurities. In order to manufacture the copper foil 200 having a PAR (Peak to Arithmetic Mean Roughness) of 0.8 to 12.5, the concentration of silver (Ag) is controlled to 50 mg/L or less.

For example, when the concentration of silver (Ag) in the electrolytic solution 11 exceeds 50 mg/L, copper is non-uniformly electrodeposited on the rotating negative electrode drum 12 and the maximum profile peak (Rp) of the copper foil 200 rapidly increases. Which can result in a PAR of over 12.5. Use raw materials that do not contain silver (Ag) to adjust the concentration of silver (Ag) in the electrolyte 11 to 50 mg/L or less. Alternatively, the silver (Ag) is prevented from flowing into the electrolyte solution 11 during the plating process. Further, in order to maintain the concentration of silver (Ag) in the electrolytic solution 11 at 50 mg/L or less, chlorine (Cl) is added to the electrolytic solution 11 to precipitate silver (Ag) in the form of silver chloride (AgCl). By doing so, silver (Ag) can be removed.

  On the other hand, the PAR (Peak to Arithmetic Mean Roughness) of the copper foil 200 may vary depending on the degree of polishing of the surface of the rotating negative electrode drum 12.

  In order to adjust the PAR (Peak to Arithmetic Mean Roughness) of the copper foil 200, the surface of the rotating negative electrode drum 12 is polished by a brush having a grain size (Grit) of, for example, #800 to #3000 before the copper layer 110 is formed.

  When the surface of the rotating negative electrode drum 12 is polished by a brush having a particle size of more than #3000, the surface profile of the rotating negative electrode drum 12 is too low to be electrodeposited very uniformly, which results in a maximum profile peak height. The roughness (Rp) may be lower than the arithmetic average roughness (Ra), and the PAR may be lowered to less than 0.8. That is, even if the silver (Ag) concentration in the electrolytic solution 11 is controlled to 50 mg/L or less, when the surface of the rotating negative electrode drum 12 is polished by a brush having a particle size exceeding #3000, the PAR is 0. It can be as low as less than 0.8.

  On the other hand, when the surface of the rotating negative electrode drum 12 is polished by a brush having a particle size of less than #800, the surface of the rotating negative electrode drum 12 becomes rough, and the maximum profile peak height (Rp) becomes the arithmetic mean roughness (Ra). ), the PAR may exceed 12.5 due to excessive increase.

  In addition, when the rotating negative electrode drum 12 is polished or buffed, water can be jetted in the width direction of the rotating negative electrode drum 12 so that the rotating negative electrode drum 12 is uniformly buffed in the width direction.

  During the process of forming the copper layer 110, the electrolyte solution 11 may be maintained at a temperature of 40 to 65°C.

  In order to reduce the content of impurities in the electrolytic solution 11, a copper wire that is a material of copper ions is heat-treated, the heat-treated copper wire is pickled, and then the pickled copper wire is put into sulfuric acid for electrolytic solution. be able to.

The electrolyte solution 11 may have a flow rate of 39 to 46 m ³ /hour. That is, the electrolytic solution 11 can be circulated at a flow rate of 39 to 46 m ³ /hour in order to remove solid impurities existing in the electrolytic solution 11 during electroplating. The electrolytic solution 11 can be filtered during the circulation process of the electrolytic solution 11. By removing silver chloride (AgCl) by such filtration, the content of silver (Ag) in the electrolytic solution 11 can be maintained at 50 mg/L or less.

If the flow rate of the electrolytic solution 11 is less than 39 m ³ /hour, the flow rate may be low and overvoltage may occur, and the copper layer 110 may be formed unevenly. On the other hand, when the flow rate exceeds 46 m ³ /hour, the filter is damaged and foreign matter can flow into the electrolytic solution 11.

  Further, in order that the copper foil 200 has a weight deviation of 3% or less in the width direction, the flow rate change amount of the electrolytic solution 11 (hereinafter referred to as “flow rate deviation”) per unit time (second) is 5% or less. Can be. If the flow rate deviation exceeds 5%, the uneven copper layer 110 may be formed due to the uneven plating, which may increase the weight deviation of the copper foil 200.

  On the other hand, the cleanliness of the electrolytic solution 11 can be maintained or improved by treating the electrolytic solution 11 with ozone or by introducing hydrogen peroxide and air into the electrolytic solution 11 while forming the copper layer 110 by electroplating. .

  Then, the copper layer 110 is cleaned in the cleaning tank 20.

  In order to remove impurities on the surface of the copper layer 110, washing with water can be performed in the washing tank 20. Alternatively, acid cleaning may be performed to remove impurities on the surface of the copper layer 110, and then water cleaning may be performed to remove the acidic solution used for the acid cleaning. The washing step can be omitted.

  Then, anticorrosion films 210 and 220 are formed on the copper layer 110.

  Referring to FIG. 8, by immersing the copper layer 110 in the rust preventive liquid 31 stored in the rust preventive tank 30, the rust preventive films 210 and 220 can be formed on the copper layer 110. Here, the anticorrosive liquid 31 contains chromium, and chromium (Cr) can exist in an ionic state in the anticorrosive liquid 31. The anticorrosive liquid 31 can contain 0.5 to 5 g/L of chromium. The rust preventive films 210 and 220 thus formed are also referred to as protective layers.

  On the other hand, the anticorrosive films 210 and 220 may contain a silane compound by a silane treatment or a nitrogen compound by a nitrogen treatment.

  The copper foil 200 is formed by forming the rust preventive films 210 and 220.

  Then, the copper foil 200 is washed in the washing tank 40. Such a washing process can be omitted.

  Then, after performing a drying process, the copper foil 200 is wound with a winder (WR).

  Hereinafter, the present invention will be specifically described based on production examples and comparative examples. However, the following production examples are only for facilitating understanding of the present invention, and the scope of rights of the present invention is not limited to these production examples.

Production Examples 1-6 and Comparative Examples 1-7
Copper foil was manufactured using a foil making machine including the electrolytic cell 10, the rotating negative electrode drum 12 disposed in the electrolytic cell 10, and the positive electrode plate 13 disposed apart from the rotating negative electrode drum 12. The electrolytic solution 11 is a copper sulfate solution, the copper ion concentration of the electrolytic solution 11 is 75 g/L, the sulfuric acid concentration is 100 g/L, the temperature of the electrolytic solution 11 is maintained at 55° C., and the electrolytic solution 11 has 60 ASD. The current was applied at the current density.

  The rotating negative electrode drum 12 was polished with a brush having a particle size (#) as disclosed in Table 1.

Electrolyte solution 11 contains silver (Ag), polyethylene glycol (PEG) and 1-phenyl-5-mercapto-1H-tetrazole (PMT) in the concentrations disclosed in Table 1. Further, the electrolytic solution 11 circulates at a flow rate of 42 m ³ /hour, and the flow rate deviation is as disclosed in Table 1.

  First, a current density of 60 ASD was applied between the rotating negative electrode drum 12 and the positive electrode plate 13 to form the copper layer 110.

  Then, the copper layer 110 was immersed in the rust preventive liquid 31 contained in the rust preventive tank 30 to form rust preventive films 210 and 220 containing chromium on the surface of the copper layer 110. At this time, the temperature of the anticorrosive liquid 31 is maintained at 30° C., and the anticorrosive liquid 31 contains 2.2 g/L of chromium (Cr). As a result, the copper foils of Production Examples 1 to 6 and Comparative Examples 1 to 7 were produced.

  The (i) PAR, (ii) tensile strength, (iii) weight deviation, and (iv) (220) face collective composition coefficient of the copper foils of Production Examples 1 to 6 and Comparative Examples 1 to 7 thus produced [TC(220)] was measured. The results are shown in Table 2.

(I) PAR measurement Rp and Ra of the copper foils manufactured in Production Examples 1 to 6 and Comparative Examples 1 to 7 were measured using SJ-310 model manufactured by Mitutoyo Corporation as a roughness meter. In the measurement of Rp and Ra, the measurement length excluding the cutoff length was 4 mm, and the cutoff length was 0.8 mm in each of the initial and final stages. The radius of the stylus tip was set to 2 μm, and the measurement pressure was set to 0.75 mN. After the above settings, Rp and Ra were repeatedly measured three times, and their average values were used as the measured values of Rp and Ra, respectively. Using Rp and Ra thus measured, PAR was calculated according to the following formula 1.

(Equation 1)
PAR=Rp/Ra

(Ii) Tensile Strength Measurement The tensile strength of the copper foils produced in Production Examples 1 to 6 and Comparative Examples 1 to 7 was measured using a universal tester manufactured by Instron in accordance with the regulations of IPC-TM-650 Test Method Manual. The sample for tensile strength measurement had a width of 12.7 mm, the distance between the grips was 50 mm, and the measurement speed was 50 mm/min. The tensile strength of the sample was repeatedly measured three times, and the average thereof was evaluated as the measurement result.

(Iii) Weight deviation measurement Samples of 5 cm x 5 cm were taken at three points in the width direction (Transverse Direction, TD) perpendicular to the winding direction of the copper foils manufactured in Manufacturing Examples 1 to 6 and Comparative Examples 1 to 7. Then, the weight of each sample was measured to calculate the weight per unit area. The "average weight" and "standard deviation of weight" were calculated from the weight per unit area of three samples, and then the weight deviation was calculated by the formula 2.

(Iv) Measurement of collective composition coefficient [TC(220)] of (220) plane For diffraction angles (2θ) of 30° to 95° with respect to the copper foils produced in Production Examples 1 to 6 and Comparative Examples 1 to 7. By performing an X-ray diffraction method (XRD) [(i) Target: Copper K alpha 1, (ii) 2θ interval: 0.01°, (iii) 2θ scan speed: 3°/min] in the range, An XRD graph having peaks corresponding to individual crystal planes was obtained. From this graph, the XRD diffraction intensity [I(hkl)] of each crystal plane (hkl) was obtained. Moreover, the XRD diffraction intensity [I ₀ (hkl)] for each of the n crystal faces of the standard copper powder defined by JCPDS (Joint Committee on Powder Diffraction Standards) was determined. Here, the crystal planes are the (111) plane, the (200) plane, the (220) plane, and the (311) plane, and n is 4.

Then, after calculating the arithmetic mean value of I(hkl)/I ₀ (hkl) of n crystal planes, I(220)/I ₀ (220) of the (220) plane is divided by the calculated arithmetic mean value. By doing so, the collective composition coefficient [TC(220)] of the (220) plane of the copper foil was calculated. The group composition coefficient [TC(220)] of the (220) plane is calculated by the following Expression 3.

(V) Observation of occurrence of sagging and tearing 1) Negative electrode production 100 parts by weight of commercially available carbon for negative electrode active material was mixed with 2 parts by weight of styrene butadiene rubber (SBR) and 2 parts by weight of carboxymethyl cellulose (CMC). A slurry for negative electrode active material was prepared using distilled water as a solvent. The slurry for negative electrode active material was applied to the copper foils of Production Examples 1 to 6 and Comparative Examples 1 to 7 having a width of 10 cm with a thickness of 40 μm using a doctor blade, dried at 120° C., and 1 ton/ A negative electrode for a secondary battery was manufactured by applying a pressure of cm ² .

2) Preparation of Electrolyte Solution A basic electrolyte solution was prepared by dissolving LiPF ₆ as a solute at a concentration of 1 M in a non-aqueous organic solvent in which ethylene carbonate (EC) and ethylene methyl carbonate (EMC) were mixed in a ratio of 1:2. .. A non-aqueous electrolyte was prepared by mixing 99.5 wt% of the basic electrolyte and 0.5 wt% of succinic anhydride.

3) Positive electrode production Li _1.1 Mn _1.85 Al _0.05 O ₄ lithium manganese oxide and o-LiMnO ₂ orthorhombic crystal lithium lithium manganese oxide 90:10 (weight ratio). ) And mixed to prepare a positive electrode active material. A positive electrode active material, carbon black, and PVDF [Poly(vinylidenefluoride)] as a binder were mixed at a ratio of 85:10:5 (weight ratio), and this was mixed with NMP as an organic solvent to prepare a slurry. The slurry thus prepared was applied to both sides of an Al foil having a thickness of 20 μm and then dried to prepare a positive electrode.

4) Manufacture of lithium secondary battery for test Coin-shaped lithium secondary battery in which a positive electrode and a negative electrode are arranged inside an aluminum can so as to be insulated from the aluminum can, and a non-aqueous electrolytic solution and a separation film are arranged between them. Was manufactured. Polypropylene (Celgard 2325; thickness 25 μm, average pore size φ28 nm, porosity 40%) was used as the separation membrane.

5) Observation of sagging and tearing Tearing and sagging of the copper foil were observed during a series of lithium secondary battery manufacturing processes. In particular, the presence or absence of tearing and sagging of the copper foil was observed with the naked eye during the manufacturing process of the copper foil and the negative electrode. The case where no sagging or tearing occurred was indicated as "good". The results of the evaluation and observation are shown in Table 2 below.

  Although sagging or tearing occurred in the copper foil during the production of the copper foil and the lithium secondary battery according to Comparative Examples 1 to 7, copper was produced during the production of the copper foil and the lithium secondary battery according to Production Examples 1 to 6. No tearing occurred on the slack in the foil.

  Specifically, in the process of manufacturing a lithium secondary battery using the following copper foil, sagging or tearing occurred in the copper foil.

(1) Comparative Example 1 having a PAR of less than 0.8 by polishing the surface of the rotating negative electrode drum 12 with a brush having a particle size (Grit) exceeding #3000 (sagging);
(2) Comparative Example 2 in which the content of silver (Ag) in the electrolytic solution exceeds 50 mg/L and the PAR exceeds 12.5 (slackening occurs);
(3) Comparative Example 3 in which the content of 1-phenyl-5-mercapto-1H-tetrazole (PMT) in the electrolytic solution is less than 2 mg/L and the tensile strength is less than 29 kgf/mm ² (sagging occurs);
(4) Comparative Example 4 in which the content of 1-phenyl-5-mercapto-1H-tetrazole (PMT) in the electrolytic solution exceeds 20 mg/L and the tensile strength exceeds 58 kgf/mm ² (tear generation);
(5) Comparative Example 5 in which the electrolyte flow rate deviation exceeds 5% per second and the weight deviation exceeds 3% (sagging occurs);
(6) Comparative Example 6 in which the content of polyethylene glycol (PEG) in the electrolytic solution is less than 2 mg/L and the collective tissue coefficient [TC(220)] of the (220) plane is less than 0.49 (sagging occurs). ;
(7) Comparative Example 7 in which the content of polyethylene glycol (PEG) in the electrolytic solution exceeds 20 mg/L and the collective composition coefficient [TC(220)] of the (220) plane exceeds 1.28 (sagging and tearing occur ).

  It can be evaluated that the copper foils according to Comparative Examples 1 to 7 are not suitable as a negative electrode current collector for a lithium secondary battery.

  On the other hand, in the case of Production Examples 1 to 6 produced under the condition range according to the embodiment of the present invention, the copper foil is not broken during the production process of the copper foil or the production process of the lithium secondary battery using the copper foil, and the copper foil is formed. There is no slack. Therefore, the copper foil according to the embodiment of the present invention has an excellent roll-to-roll (RTR) processability and can be effectively used as a negative electrode current collector for a lithium secondary battery.

  The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and the present invention is capable of various substitutions, modifications and changes without departing from the technical matters of the present invention. It will be apparent to one of ordinary skill in the art. Therefore, the scope of the present invention is limited by the scope of the claims to be described later, and all modifications or variations derived from the meaning of the scope of the claims, the scope and the equivalent concept thereof are construed to be included in the scope of the present invention. There must be.

100, 200 Copper foil 210, 220 Rust preventive film 310 Active material layer 300, 400 Secondary battery electrode 340 Secondary battery negative electrode 370 Secondary battery positive electrode MS matte surface SS shiny surface

Claims (8)

Including a copper layer and an anticorrosive film disposed on the copper layer,
PAR of 0.8 to 12.5 (Peak to Arithmetic Mean Roughness),
A tensile strength of 29 to 58 kgf/mm ² and a weight deviation of 3% or less,
Have
A (220) plane, and the texture coefficient [TC(220)] of the (220) plane is 0.49 to 1.28;
The PAR is calculated by the following formula 1,
(Equation 1)
PAR=Rp/Ra
In Formula 1, Rp is a maximum profile peak height, and Ra is an arithmetic mean roughness.   The copper foil according to claim 1, wherein the rustproof film contains at least one of chromium (Cr), a silane compound, and a nitrogen compound.   The copper foil according to claim 1, having a thickness of 4 μm to 30 μm. Copper foil, and the active material layer disposed on the copper foil according to any one of claims 1 to 3
An electrode for a secondary battery, including: A cathode,
An anode arranged opposite to the cathode,
An electrolyte that is disposed between the positive electrode and the negative electrode and provides an environment in which ions can move, and a separator that electrically insulates the positive electrode and the negative electrode from each other,
The negative electrode is
Active material layer disposed foil, and on the copper foil according to any one of claims 1 to 3,
Including a secondary battery. Polymer film, and the copper foil according to any one of the polymer film 1 to claim arranged on 3,
Including a flexible copper foil laminated film. The step of polishing the surface of the rotating anode drum brush particle size of # 800 to # 3000, and a positive electrode plate and the rotary anode drum which is spaced apart from each other in the electrolytic solution in the containing copper ion 40 to 80 A / dm ² Including forming a copper layer by energizing at a current density of
The flow rate deviation per unit time (second, second) is 5% or less,
The electrolytic solution is
70-90 g/L copper ion,
50-150 g/L sulfuric acid,
50 mg/L or less of silver (Ag),
2 to 20 mg/L of 1-phenyl-5-mercapto-1H-tetrazole (1-Phenyl-5-mercapto-1H-tetrazole), and 2 to 20 mg/L of polyethylene glycol (PEG),
And a method for producing a copper foil. The method for producing a copper foil according to claim 7 , wherein the electrolytic solution has a flow rate of 39 to 46 m ³ /hour.