JP6767441B2 - Copper foil with minimized sagging, wrinkles and tearing, electrodes containing it, secondary batteries containing it, and methods for manufacturing them. - Google Patents

Description

The present invention relates to a copper foil with minimized sagging, wrinkles and tears, an electrode containing the same, a secondary battery containing the same, and a method for manufacturing the same.

Copper foil is used in the manufacture of various products such as negative electrodes of secondary batteries and flexible printed circuit boards (FPCBs).

On the other hand, the copper foil produced by electroplating is also called electrolytic copper foil. Such electrolytic copper foils are generally manufactured in a roll-to-roll (RTR) process. The electrolytic copper foil produced by the roll-to-roll (RTR) process is used for producing a negative electrode of a secondary battery, a flexible printed circuit board (FPCB), etc. by the roll-to-roll (RTR) process. Since continuous production is possible, the roll-to-roll process is known to be a process suitable for mass production of products. However, if the copper foil breaks or tears during the roll-to-roll process, or if the copper foil sags or wrinkles, the operation of the roll-to-roll process equipment is interrupted, causing problems. After the solution, the equipment must be restarted, which reduces productivity.

In particular, when sagging, wrinkling, or tearing occurs in the copper foil during the process of manufacturing the secondary battery using the copper foil, stable product production becomes difficult. The sagging, wrinkling, or tearing of the copper foil generated in the manufacturing process of the secondary battery is a factor that lowers the manufacturing yield of the secondary battery and increases the manufacturing cost of the product.

Among the causes of sagging, wrinkling, or tear failure generated in the copper foil, a method of controlling the weight deviation of the copper foil to a low level is known as a method of solving the cause caused by the copper foil itself. However, there is a limit in solving the problem of sagging, wrinkling, or tearing of the copper foil that occurs 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 a secondary battery, the ratio of ultra-thin copper foil, for example, a copper foil having a thickness of 8 μm or less, is increasing as a negative electrode current collector. In this case, even if the weight deviation of the copper foil is precisely controlled, sagging, wrinkling, or tear failure occurs intermittently in the manufacturing process of the secondary battery. Therefore, it is necessary to prevent or suppress the occurrence of sagging, wrinkling or tearing of the copper foil.

The present invention attempts to provide a copper foil capable of solving such problems, an electrode containing the copper foil, a secondary battery including the copper foil, and a method for manufacturing the same.

One embodiment of the present invention seeks to provide a copper foil with minimal sagging, wrinkling or tearing. One embodiment of the present invention provides a copper foil that has excellent roll-to-roll (RTR) processability, especially by preventing the occurrence of sagging, wrinkling or tearing in the manufacturing process, even if it has a small thickness. try to.

Another embodiment of the present invention is intended 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 attempts 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 making a copper foil that can prevent the occurrence of sagging, wrinkling or tearing during the manufacturing process.

In addition to the above-mentioned viewpoints of the present invention, other features and advantages of the present invention will be described below, or such description will be clearly understandable to those who have ordinary knowledge in the art to which the present invention belongs. Will.

In order to solve such a problem, one embodiment of the present invention includes a copper layer, has a tensile strength of 29 to 65 kgf / mm ² , and has a roughness profile element average spacing of 18 to 148 μm (mean width of roofness profile elements). ) (Rsm), and a set employment coefficient bias [TCB (220)] of 0.52 or less.

The copper foil may further include a rust preventive film disposed on the copper layer.

The rust preventive film can contain at least one of chromium (Cr), a silane compound and a nitrogen compound.

The copper foil can have a maximum height roughness (Rmax) of 0.6 μm or more.

The copper foil can have a weight deviation of 5% or less.

The copper foil can have an elongation rate of 2% or more at room temperature of 25 ± 15 ° C.

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

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

Yet another embodiment of the present invention provides a cathode, a negative electrode arranged to face the positive electrode, and an environment arranged between the positive electrode and the negative electrode where ions can move. The negative electrode includes the electrolyte and a separator that electrically insulates the positive electrode from the negative electrode, and the negative electrode contains the copper foil and an active material layer arranged on the copper foil. Provide secondary batteries including.

Another embodiment of the present invention provides a flexible copper foil laminated film containing a polymer film and the copper foil arranged on the polymer film.

In another embodiment of the present invention, a positive electrode plate and a rotating negative electrode drum arranged apart from each other in an electrolytic solution containing copper ions are energized at a current density of 30 to 80 A / dm ² to form a copper layer. The electrolyte comprises 70-100 g / L copper ions, 80-130 g / L sulfuric acid, 2-20 mg / L 2-Mercaptothiazoline, 2-20 mg / L bis (2-20 mg / L bis. Provided is a method for producing a copper foil containing 3-sulfopropyl) disulfide [bis- (3-sulfopropyl) disulfide] (SPS) and polyethylene glycol (PEG) of 50 mg / L or less.

The electrolytic solution can contain 10 to 30 mg / L of chlorine (Cl).

The flow rate deviation per unit time (seconds, seconds) of the electrolytic solution may be 5% or less.

The copper foil according to one embodiment of the present invention has excellent resistance to sagging, wrinkling or tearing. That is, according to one embodiment of the present invention, the occurrence of sagging, wrinkling, or tearing during the manufacturing process of the copper foil or the manufacturing process of the secondary battery using the copper foil is prevented. Therefore, the copper foil according to one embodiment of the present invention has excellent roll-to-roll processability.

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

The accompanying drawings are intended to form a part of the present specification in order to help the understanding of the present invention, exemplify examples of the present invention, and explain the principles of the present invention together with a detailed description of the invention.
It is the schematic sectional drawing of the copper foil by one Example of this invention. It is a figure which shows the XRD graph of a copper foil. It is a graph of the roughness profile element (roughness profile element). It is the schematic sectional drawing of the copper foil by another Example of this invention. It is the schematic sectional drawing of the electrode for a secondary battery by still another Example of this invention. It is the schematic sectional drawing of the electrode for a secondary battery by still another Example of this invention. It is the schematic sectional drawing of the secondary battery by still another Example of this invention. It is sectional drawing of the flexible copper foil laminated film by still another Example of this invention. It is the schematic which shows the manufacturing process of the copper foil shown in FIG. It is a photograph which shows the sagging (bagginess) of a copper foil. It is a photograph which shows the wrinkle (wrinkle) of a copper foil.

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 modifications of the present invention are possible within the scope of the technical idea and scope of the present invention. Therefore, the present invention includes all modifications and modifications within the scope of the invention and its equivalents described in the claims.

The shapes, dimensions, ratios, angles, numbers, and the like disclosed in the drawings for explaining the examples of the present invention are exemplary, and thus the present invention is not limited to the matters shown in the drawings. The same components are designated by the same reference numerals throughout the specification.

When ‘include’, ‘have’, ‘become’, etc. are used herein, other parts may be added unless the expression ‘only’ is used. When a component is expressed in the singular, it includes more than one unless otherwise specified. In addition, in the interpretation of the components, it is interpreted as including the error range even if there is no separate explicit description.

In the case of the explanation of the positional relationship, the positional relationship of the two parts is explained, for example,'on the',' on the upper part of',' on the lower part of',' by the side of', and so on. In some cases, one or more other parts may be located between the two parts, unless the expression'immediate'or'direct' is used.

When explaining the temporal relationship, for example,'after',' following',' after',' before', etc.,' Unless the expression'immediately'or'directly' is used, it may include non-continuous cases.

Expressions such as'first'and'second' are used to describe various components, but these components are not limited to such terms. Such terms are used solely to distinguish one component 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" must be understood to include all combinations that can be presented from one or more related items.

Each feature of many embodiments of the invention can be partially or wholly coupled to or combined with each other, technically diverse interlocking and driving, and each embodiment is independent of each other. It can be carried out, or it can be carried out together in a relational relationship.

FIG. 1 is a schematic cross-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. According to one embodiment of the present invention, the copper foil 100 includes a rust preventive film 210 arranged on the copper layer 110. The rust preventive film 210 can be omitted.

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

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

It is common for the shiny surface SS to have a lower surface roughness (Rz) than the matte surface MS, but 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 can be arranged on at least one of the matte surface MS and the shiny surface SS of the copper layer 110. With reference to FIG. 1, the rust preventive film 210 is arranged on the matte surface MS. However, one embodiment of the present invention is not limited to this, and the rust preventive film 210 may be arranged only on the shiny surface SS, or may be arranged on both the matte surface MS and the shiny surface SS. it can.

The rust preventive film 210 protects the copper layer 110. The rust preventive film 210 can prevent the copper layer 110 from being oxidized or denatured during the storage process. If the rust preventive film 210 is not arranged on the copper layer 110, surface oxidation may occur on the copper layer 110 over time, which may shorten the life of a device containing the copper foil 100, for example, a secondary battery. .. Such a rust preventive film 210 is also called 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 one embodiment of the present invention, the rust preventive film 210 can contain at least one of chromium (Cr), a silane compound and a nitrogen compound.

For example, the rust preventive film 210 can be formed with a rust preventive liquid containing chromium (Cr), that is, a rust preventive liquid containing a chromic acid compound.

According to one embodiment of the present invention, the copper foil 100 has a first surface S1 which is a surface in the matte surface MS direction and a second surface S2 which is a surface in the shiny surface SS direction with reference 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. When the rust preventive film 210 is not arranged on the copper layer 110, the matte surface MS of the copper layer 110 becomes the first surface S1 of the copper foil 100.

According to one embodiment of the present invention, the copper foil 100 has a collective cohesive coefficient bias (Texture Cofficient Bias, TCB) of 0.52 or less.

More specifically, the texture coefficient bias [TCB (220)] of the (220) plane of the copper foil 100 is 0.52 or less. According to one embodiment of the present invention, the collective formation coefficient bias [TCB (220)] of the (220) surface of the copper foil 100 is also referred to as the collective formation coefficient bias [TCB (220)] of the copper foil 100.

The (220) plane assembly coefficient bias [TCB (220)] indicates the deviation or tendency of the (220) plane assembly coefficient [TC (220)] depending on the position. The assembly coefficient bias [TCB (220)] is related to the crystal structure on the surface of the copper foil 100. The collective employment coefficient bias [TCB (220)] of the (220) plane can be obtained by the following equation 1. Specifically, [TC (220)] (coefficient of collective employment on 220 faces) was measured three times at each of the left, center, and right points in the width direction of the copper foil 100 (see Equation 2 below). At this time, the highest [TC (220)] value is TCmax, and the lowest [TC (220)] value is TCmin. The collective employment coefficient bias [TCB (220)] is calculated as the difference between TCmax and TCmin, that is, the "TCmax-TCmin" value.

(Equation 1)
Group job coefficient bias [TCB (220)] = TCmax-TCmin

On the other hand, the standard for collecting a sample in the width direction of the copper foil 100 can be applied in the same manner as in the weight deviation measuring method.

With reference to Equation 1, the set-form coefficient bias [TCB (220)] of the (220) plane is obtained from the set-form coefficient [TC (220)] of the (220) plane.

Hereinafter, with reference to FIG. 2, a method for measuring and calculating the collective employment coefficient [TC (220)] of the (220) plane according to an embodiment of the present invention will be described.

FIG. 2A is a diagram showing an XRD graph of a copper foil. More specifically, FIG. 2A is an XRD graph of the copper foil 100.

In the measurement of the aggregation coefficient [TC (220)] of the (220) plane, first, n crystal planes are formed by X-ray diffraction (XRD) in the range of the diffraction angle (2θ) of 30 ° to 95 °. An XRD graph with the corresponding peak is obtained [Target: Copper Kalpha 1,2θ interval: 0.01 °, 2θ scan speed: 3 ° / min]. For example, as shown in FIG. 2A, an XRD graph showing four peaks corresponding to planes (111), (200), (220), and (311) can be obtained. With reference to FIG. 2A, n is 4.

Then, the XRD diffraction intensity [I (hkl)] of each crystal plane (hkl) is obtained from this graph. In addition, the XRD diffraction intensity [I ₀ (hkl)] for each of the n crystal planes of the standard copper powder defined by JCPDS (Joint Committee on Power Diffraction Standards) is obtained. Then, the arithmetic mean value for "I (hkl) / I ₀ (hkl)" of n crystal planes is calculated, and the arithmetic mean value is divided by I (220) / I ₀ (220) of the (220) plane. By doing so, the set composition coefficient [TC (220)] of the (220) plane is calculated. That is, the set grouping coefficient [TC (220)] of the (220) plane is calculated by the following equation 2.

(Equation 2)

According to one embodiment of the present invention, the (220) plane of the copper foil 100 can have an assembly coefficient bias [TCB (220)] of 0.52 or less. That is, the copper foil 100 can have an assembly coefficient [TC (220)] of 0.52 or less.

When the collective assembly coefficient bias [TCB (220)] of the (220) plane exceeds 0.52, due to the difference in local collective formation due to the difference in local crystal structure in the layer 110 or the copper foil 100, The copper foil 100 is easily deformed by the tension applied to the copper foil in the process of manufacturing the copper foil 100 by the roll-to-roll process, which may cause wrinkles in the copper foil 100.

Therefore, according to one embodiment of the present invention, the collective employment coefficient [TC (220)] of the (220) plane of the copper foil 100 is maintained at a low level of 0.52 or less.

According to one embodiment of the present invention, the copper foil 100 has a tensile strength of 29 to 65 kgf / mm ² . Tensile strength can be measured with a universal tester (UTM) according to the IPC-TM-650 Test Method Manual. According to one embodiment of the present invention, the tensile strength is measured with a universal tester manufactured by Instron. Here, the width of the sample for measuring tensile strength is 12.7 mm, the distance between grips is 50 mm, and the measurement speed is 50 mm / min. For evaluation, the tensile strength of the sample can be repeatedly measured over three times, and the average value can be 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 , the copper foil 100 cannot withstand the force such as tension applied to the copper foil 100 in the manufacturing process, and the copper during the roll-to-roll process. Wrinkles may occur on the foil 100.

On the other hand, if the tensile strength of the copper foil 100 exceeds 65 kgf / mm ² , the tensile strength of the copper foil 100 is excellent, and the copper foil 100 sufficiently withstands forces such as tension applied to the copper foil 100 in the manufacturing process. , The brittleness of the copper foil 100 itself increases, and the copper foil 100 cannot be stretched in response to the force locally applied to the copper foil 100 during the roll-to-roll process, so that the copper foil 100 may be torn. is there. As a result, the usability of the copper foil 100 is reduced. For example, tearing may occur in the copper foil manufacturing process or the secondary battery electrode manufacturing process using the copper foil, which may make it difficult to manufacture a stable product.

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 part must be removed, and then the process equipment must be restarted. As a result, process time and cost increase, and productivity decreases.

According to one embodiment of the present invention, the copper foil 100 has a roughness profile element average spacing (mean width of roofness profile elements) (Rsm) of 18 to 148 μm.

The roughness profile element average spacing (Rsm) can be measured with a roughness meter according to the JIS B 0601-2001 standard. According to one embodiment of the present invention, the roughness profile element average spacing (Rsm) was measured with the SJ-310 model of Mitutoyo. Here, the measured length excluding the cutoff length is 4 mm, and the cutoff length is 0.8 mm at the initial stage and the final stage, respectively. The radius of the stylus tip is 2 μm.

FIG. 2B is a graph of roughness profile elements (roughness profile elements).

Referring to FIG. 2B, the roughness profile element average spacing (Rsm) is the distance (XSi,) from the point where one peak (valley) intersects the mean line (ML) to the corresponding point of the adjacent peak (valley). Here, it is the arithmetic mean value of i = 1, 2, 3, ..., M). Specifically, the roughness profile element average interval (Rsm) can be obtained by the following equation 3.

(Equation 3)

Roughness profile element average spacing (Rsm) is suitable for evaluating surfaces with periodic textures.

If the roughness profile element average spacing (Rsm) is less than 18 μm, the surface is too uneven and the tension is concentrated in the unevenness during the manufacturing process of the copper foil 100 by the Roll To Roll process. This increases the probability that the copper foil 100 will tear.

On the other hand, if the average spacing (Rsm) of the roughness profile elements exceeds 148 μm, the spacing between the irregularities is too large and slips are likely to occur in the process of manufacturing the copper foil 100 by the Roll To Roll process. As a result, the copper foil 100 may be wrinkled.

According to one embodiment of the present invention, the copper foil 100 has a maximum height roughness (Rmax) of 0.6 μm or more.

The maximum height roughness (Rmax) can be measured with a roughness meter according to JIS B 0601-2001 standard. According to one embodiment of the present invention, the maximum height roughness (Rmax) can be measured with the SJ-310 model of Mitutoyo. Specifically, the measured length excluding the cutoff length is 4 mm, and the cutoff length is 0.8 mm at the initial stage and the final stage, respectively. The radius of the stylus tip is 2 μm, and the measurement pressure is 0.75 mN.

When the maximum height roughness (Rmax) is less than 0.6 μm, when the copper foil 100 is wound around a bobbin or a winder, a phenomenon occurs in which the copper foil 100 is locally stretched due to weight superposition between the copper foils 100. Poor sagging may occur.

According to one embodiment of the present invention, the copper foil 100 can have a maximum height roughness (Rmax) of 3.5 μm or less. When the maximum height roughness (Rmax) of the copper foil 100 exceeds 3.5 μm, when the copper foil 100 is wound around a bobbin or a winder in the manufacturing process of the copper foil 100 by the roll-to-roll (RTR) process, the copper foil Air may be trapped between the copper foil and the copper foil to cause baggings.

According to one embodiment of the present invention, the copper foil 100 has a weight deviation of 5% or less. More specifically, the copper foil 100 can have a weight deviation of 0-5%. Here, when the weight deviation is 0, it means that there is no weight deviation.

According to one embodiment of the present invention, the weight deviation can be obtained from the average weight (average weight) and the standard deviation of the weight measured at any three points in the width direction of the copper foil 100. Specifically, after taking a sample of 5 cm × 5 cm at three points arranged in the width direction of the copper foil 100, that is, the direction perpendicular to the winding direction (Transverse Direction, TD), the weight of each sample is measured. After calculating the weight per unit area and calculating the "average weight" and "standard deviation of weight" at three points from the weight per unit area of the three samples, the weight deviation can be calculated by Equation 4.

(Equation 4)

If the weight deviation of the copper foil 100 exceeds 5%, when the copper foil 100 is wound up in the roll-to-roll process, a phenomenon occurs in which the copper foil 100 is locally stretched due to the weight superposition between the copper foils 100, and the copper foil 100 is stretched locally. Sagging may occur in 100.

According to one embodiment of the present invention, the copper foil 100 has an elongation rate of 2% or more at room temperature of 25 ± 15 ° C. Elongation can be measured with a universal tester (UTM) by the method specified in IPC-TM-650 Test Method Manual. According to one embodiment of the present invention, equipment manufactured by Instron can be used. Here, the width of the sample for measuring the elongation rate is 12.7 mm, the distance between grips is 50 mm, and the measurement speed is 50 mm / min. After measuring the elongation rate three times, the average value can be used as the elongation rate value.

If the elongation rate of the copper foil 100 is less than 2%, there is a risk that the copper foil 100 cannot be stretched and is torn in response to the force applied in the manufacturing process of the copper foil 100.

More specifically, the copper foil 100 can have an elongation rate of 2 to 20%.

According to one embodiment of the present invention, the copper foil 100 can have a thickness of 4 μm to 30 μm. When the thickness of the copper foil 100 is less than 4 μm, the workability is lowered in the manufacturing process of the copper foil 100 or the manufacturing process of the product using the copper foil 100, for example, the electrode for the secondary battery or the secondary battery. When the thickness of the copper foil 100 exceeds 30 μm, the thickness of the electrode for the secondary battery using the copper foil 100 becomes large, and such a large thickness makes it difficult to realize a high capacity of the secondary battery. Sometimes.

According to one embodiment of the present invention, saggins and wrinkles are distinguished from each other.

FIG. 9 is a photograph illustrating the sagging of copper foil. In FIG. 9, the portion indicated by the arrow (↑) is the portion where the slack has occurred. According to one embodiment of the present invention, the slack refers to a state in which the copper foil 100 is locally stretched and does not spread flatly or a portion thereof.

FIG. 10 is a photograph illustrating the slack (wrinkle) of the copper foil. In FIG. 10, the portion indicated by the arrow (↑) is the portion where the slack has occurred. According to one embodiment of the present invention, slack refers to a state in which the copper foil 100 is locally folded or a portion thereof.

However, one embodiment of the present invention is not limited to this, and can be expressed by one term in the two without distinguishing between saggins and wrinkles. For example, the case where the copper foil 100 is locally stretched and does not spread flat and the case where the copper foil 100 is locally folded are not distinguished and are both expressed as "sag" or "wrinkles". You can also do it.

That is, both of them can be expressed as "sag" or "wrinkle" without distinguishing between sagging and wrinkle.

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

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

For convenience of explanation, of the two rust preventive films 210 and 220, the rust preventive film 210 arranged on the matte surface MS of the copper layer 110 is arranged on the first protective layer and the shiny surface SS. Can be said to be the second protective layer.

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 matte surface MS, and the second surface S2 is the surface of the rust preventive film 220 arranged on the shiny surface SS. Is the same as.

According to another embodiment of the present invention, the two rust preventive films 210 and 220 can each contain at least one of chromium (Cr), a silane compound and a nitrogen compound.

The (220) plane of the copper foil 200 shown in FIG. 3 has an assembly coefficient bias [TCB (220)] of 0.52 or less.

In addition, the copper foil 200 shown in FIG. 3 has a tensile strength of 29 to 65 kgf / mm ² and a roughness profile element average spacing (mean width of roofness profile elements) (Rsm) of 18 to 148 μm. Further, the copper foil 200 has a maximum height roughness (Rmax) of 0.6 μm or more, a weight deviation of 5% or less, an elongation rate of 2% or more at room temperature of 25 ± 15 ° C., and 4 μm to 30 μm. Has a thickness of.

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

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

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

Specifically, the 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 S2 of the copper foil 100. Includes an active material layer 310 disposed on at least one of the above. Further, the copper foil 100 includes a copper layer 110 and a rust preventive film 210 arranged on the copper layer 110.

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

Further, although 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, still another embodiment of the present invention is limited to this. It is not something that is done. The active material layer 310 can be arranged on both the first surface S1 and the second surface S2 of the copper foil 100, and the active material layer 310 can be arranged 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 can be made of a negative electrode active material in particular. That is, the secondary battery electrode 300 shown in FIG. 4 can be used as a negative electrode.

The active material layer 310 can contain at least one of carbon, metal, metal oxides and metal-carbon composites. As the metal, at least one of Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe can be used. Further, in order to increase the charge / discharge capacity of the secondary battery, the active material layer 310 may contain silicon (Si).

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

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

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

Referring to FIG. 5, the copper foil 200 includes two rust preventive films 210 and 220 arranged on the double-sided MS and SS of the copper layer 110 and the copper layer 110. Further, the secondary battery electrode 300 shown in FIG. 5 includes two active material layers 310 and 320 arranged on both sides of the copper foil 200. Here, the active material layer 310 arranged on the first surface S1 of the copper foil 200 is the first active material layer, and the active material layer 320 arranged on the second surface S2 of the copper foil 200 is the second active material layer. It can be said that.

Both active material layers 310 and 320 can be formed from the same material by the same method, and can be formed by different materials or different methods.

FIG. 6 is a schematic cross-sectional view of the 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, the secondary battery 500 is arranged between the positive electrode (cathode) 370, the negative electrode (anode) 340 arranged opposite to the positive electrode 370, and the positive electrode 370 and the negative electrode 340, and ions move. Includes an electrolyte 350 that provides an environment in which the electrode can be formed, and a separator 360 that electrically insulates the positive electrode 370 and the negative electrode 340. Here, the ions that move between the positive electrode 370 and the negative electrode 340 are lithium ions. The separation membrane 360 separates the positive electrode 370 and the negative electrode 340 in order to prevent the electric charge generated in one electrode from moving to another electrode through the inside of the secondary battery 500 and being wasted. With reference to FIG. 6, the separation membrane 360 is placed in 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 contains 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 electrodes 300 and 400 for the secondary battery 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 cross-sectional view of the flexible copper foil laminated film 600 according to still another embodiment of the present invention.

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

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

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 arranged 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.

With reference to FIG. 7, a polymer film 410 arranged on the rust preventive film 210 is illustrated, but still another embodiment of the present invention is not limited thereto. The polymer film 410 can also be arranged on the shiny surface SS of the copper layer 110.

Hereinafter, a method for producing the copper foil 200 according to another embodiment of the present invention will be specifically described 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 arranged apart from each other in the electrolytic solution 11 containing copper ions are energized at a current density of 30 to 80 ASD (A / dm ² ) to form the copper layer 110.

Specifically, referring to FIG. 8, a current density of 40 to 80 ASD (A / dm ² ) is applied to the positive electrode plate 13 and the rotating negative electrode drum 12 arranged in the electrolytic solution 11 housed in the electrolytic cell 10. The copper layer 110 is formed by electrolyzing copper onto the rotating negative electrode drum 12. At this time, the distance between the positive electrode plate 13 and the rotating negative electrode drum 12 can be adjusted in 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, the more uniformly electrodeposition is performed, the less the surface roughness of the matte surface MS of the copper layer 110 decreases, and the lower the current density, the more unevenly plated. The surface roughness of the matte surface MS of the copper layer 110 is increased.

The electrolytic solution 11 contains 70 to 100 g / L of copper ions and 80 to 130 g / L of sulfuric acid. The temperature of the electrolyte is maintained at 50-70 ° C. Copper can be easily electrodeposited on the rotating negative electrode drum 12 in the electrolytic solution 11 having such a concentration.

Further, the electrolytic solution 11 is an organic substance, and is 2 to 20 mg / L of 2-mercaptothiazoline and 2 to 20 mg / L of bis (3-sulfopropyl) disulfide [bis- (3-sulfopolyethylene) disulfide]. Contains (SPS) and polyethylene glycol (PEG) of 50 mg / L or less.

2-mercaptothiazoline is also referred to as "MTZ" and can be expressed by the following chemical formula 1.

2-Mercaptothiazolin (MTZ) functions as a grain refinement in the process of manufacturing the copper layer 110. If the concentration of 2-mercaptothiazolin (MTZ) in the electrolytic solution 11 is less than 2 mg / L, the grain refinement by 2-mercaptothiazolin (MTZ) is not sufficient, and the tensile strength of the copper foil 200 is 29 kgf /. It is less than mm ² . On the other hand, if the concentration of 2-mercaptothiazolin (MTZ) exceeds 20 mg / L, the grain refinement by 2-mercaptothiazolin (MTZ) becomes excessive and the tensile strength of the copper foil 200 exceeds 65 kgf / mm ^2. become.

If the concentration of bis (3-sulfopropyl) disulfide (SPS) acting as a brightener in the electrolytic solution 11 becomes excessively high above 20 mg / L, the surface of the copper layer 110 is formed too uniformly. The number of irregularities per unit interval is reduced, so that the average spacing (Rsm) of the roughness profile elements of the copper foil 200 exceeds 148 μm. On the other hand, if the concentration of bis (3-sulfopropyl) disulfide (SPS) is less than 2 mg / L, the concentration of the brightener that makes the surface uniform during copper electrodeposition is too low and the surface of the copper layer 110 is non-uniform. Is formed in. As a result, the number of irregularities per unit section of the copper foil 200 increases, and the roughness profile element average spacing (Rsm) becomes less than 18 μm.

Polyethylene glycol (PEG) serves to flatten the surface of the copper layer 110 during copper electrodeposition. Therefore, as the concentration of polyethylene glycol (PEG) in the electrolytic solution 11 increases, the smoothness of the copper layer 110 increases. When the concentration of polyethylene glycol (PEG) in the electrolytic solution 11 exceeds 50 mg / L, the surface smoothness of the copper foil 200 becomes high, and the maximum height roughness (Rmax) of the copper foil 200 becomes less than 0.6 μm. Become.

The electrolytic solution 11 contains silver (Ag) of 50 mg / L or less. Here, silver (Ag) includes an ionic state (Ag ⁺ ) dissociated in the electrolytic solution 11 and a non-dissociated state (Ag), and also includes all states existing as salts. In general, silver (Ag) is an impurity in the electrolytic solution 11. If the concentration of silver (Ag) in the electrolytic solution 11 exceeds 50 mg / L, copper may be excessively non-uniformly electrodeposited on the rotating negative electrode drum 12. Therefore, the concentration of silver (Ag) in the electrolytic solution 11 is controlled to 50 mg / L or less.

In order to control the concentration of silver (Ag) in the electrolytic solution 11 to 50 mg / L or less, chlorine (Cl) is added to the electrolytic solution 11 so that silver (Ag) precipitates in the form of silver chloride (AgCl). Silver (Ag) can be removed by setting. For example, the electrolytic solution 11 can contain 10 to 30 mg / L of chlorine (Cl). Here, chlorine (Cl) includes all chlorine ions (Cl ⁻ ) and chlorine atoms existing in the molecule. Specifically, chlorine (Cl) can precipitate silver (Ag) ions in the form of silver chloride (AgCl). Such silver chloride (AgCl) can be removed by filtration.

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

The electrolyte 11 can have a flow rate of 35 to 50 m ³ / hour. That is, in order to remove the solid impurities present in the electrolytic solution 11 in the process of forming the copper layer 110 by electrodeposition, the electrolytic solution 11 can be circulated at a flow rate of 35 to 50 m ³ / hour. The electrolytic solution 11 can be filtered in the circulation process of the electrolytic solution 11. By removing impurities such as silver chloride (AgCl) by such filtration, the cleanliness of the electrolytic solution 11 can be maintained.

According to one embodiment of the present invention, the amount of change in the flow rate of the electrolytic solution 11 (hereinafter referred to as “flow rate deviation”) per unit time (second) can be set to 5% or less. If the flow rate deviation exceeds 5%, the non-uniform plating may form a non-uniform copper layer 110, which causes the texture coefficient bias [TCB (220)] of the (220) plane of the copper foil 100. It will exceed 0.52.

On the other hand, the cleanliness of the electrolytic solution 11 can be maintained or improved by adding hydrogen peroxide and air to the electrolytic solution 11 while the electrolytic solution 11 is ozone-treated or the copper layer 110 is formed by electroplating.

Then, the copper layer 110 is washed in the washing 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, pickling (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 pickling. The cleaning step can be omitted.

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

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

On the other hand, the rust preventive films 210 and 220 may contain a silane compound by silane treatment, and may also contain a nitrogen compound by 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 cleaning step can be omitted.

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

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

Production Examples 1 to 6 and Comparative Examples 1 to 6
Copper foil was produced using a foil making machine including an electrolytic cell 10, a rotating negative electrode drum 12 arranged in the electrolytic cell 10, and a positive electrode plate 13 arranged 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 concentration of chlorine ions (Cl ⁻ ) is 17 mg / L, and the temperature of the electrolytic solution 11 is It was maintained at 55 ° C.

The electrolyte 11 contains 2-mercaptothiazolin (MTZ), bis (3-sulfopropyl) disulfide (SPS) and polyethylene glycol (PEG) at 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 was applied between the rotating negative electrode drum 12 and the positive electrode plate 13 at a current density of 60 ASD to form a copper layer 110.

Then, by immersing the copper layer 110 in the rust preventive liquid 31 contained in the rust preventive tank 30, the rust preventive films 210 and 220 containing chromium were formed on the surface of the copper layer 110. At this time, the temperature of the rust preventive liquid 31 is maintained at 30 ° C., and the rust preventive 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 6 were produced.

With respect to the copper foils of Production Examples 1 to 6 and Comparative Examples 1 to 6 produced in this manner, the collective employment coefficient bias [TCB (220)] of the (i) and (220) planes, (ii) tensile strength, (ii) iii) Roughness profile element average spacing (Rsm) and (iv) maximum height roughness (Rmax) were measured.

The results are shown in Table 2.

(I) Measurement of collective employment coefficient bias [TCB (220)] on the (220) plane First, the collective employment coefficient on the (220) plane of the copper foils manufactured in Production Examples 1 to 6 and Comparative Examples 1 to 6 [ TCB (220)] was measured.

X-ray diffraction (XRD) [(i) Target: Copper K alpha 1) in the range of a diffraction angle (2θ) of 30 ° to 95 ° with respect to the copper foils produced in Production Examples 1 to 6 and Comparative Examples 1 to 6. , (Ii) 2θ interval: 0.01 °, (iii) 2θ scan speed: 3 ° / min] to obtain an XRD graph having peaks corresponding to n crystal planes. From this graph, the XRD diffraction intensity [I (hkl)] of each crystal plane (hkl) was obtained. In addition, the XRD diffraction intensity [I ₀ (hkl)] for each of the n crystal planes of the standard copper powder defined by JCPDS (Joint Committee on Power 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, divide the I (220) / I ₀ (220) of the (220) plane by the obtained arithmetic mean value. As a result, the collective employment coefficient [TC (220)] of the (220) plane of the copper foil was calculated. The set structure coefficient [TC (220)] of the (220) plane was calculated by the following equation 2.

(Equation 2)

Using the (220) plane assembly coefficient [TC (220)], the (220) plane assembly coefficient bias [TCB (220)] was measured by the following equation 1.

Specifically, [TC (220)] (coefficient of collective employment on 220 faces) was measured three times at each of the left, center, and right points in the width direction of the copper foil 100, and the average was calculated. At this time, the highest [TC (220)] value is TCmax, and the lowest [TC (220)] value is TCmin. Then, the difference between TCmax and TCmin, that is, the "TCmax-TCmin" value was calculated to calculate the collective employment coefficient bias [TCB (220)].

(Equation 1)
Group job coefficient bias [TCB (220)] = TCmax-TCmin

(Ii) Tensile Strength Measurement The tensile strength of the copper foils produced in Production Examples 1 to 6 and Comparative Examples 1 to 6 was measured with a universal tester manufactured by Instron in accordance with the provisions of IPC-TM-650 Test Method Manual. The width of the sample for measuring the tensile strength was 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 over 3 times, and the average was evaluated as the measurement result.

(Iii) Measurement of Roughness Profile Element Average Interval (Rsm) The roughness profile element average interval (Rsm) was measured with a roughness meter according to JIS B 0601-2001 standard. Specifically, the roughness profile element average spacing (Rsm) was measured with the SJ-310 model of Mitutoyo. Here, the measured length excluding the cutoff length was 4 mm, and the cutoff length was 0.8 mm at the initial stage and the final stage, respectively. Further, the radius of the stylus tip was 2 μm.

In the surface roughness profile, when the distance from the point where one peak (valley) intersects the average line (ML) to the corresponding point of the adjacent peak (valley) is XSi, the roughness profile element average spacing (Rsm) Can be obtained by the following equation 3.

(Equation 3)

(Iv) Measurement of maximum height roughness (Rmax) The maximum height roughness (Rmax) was measured with a roughness meter according to the JIS B 0601-2001 standard. Specifically, the maximum height roughness (Rmax) was measured with the SJ-310 model of Mitutoyo. Here, the measured length excluding the cutoff length was 4 mm, and the cutoff length was set to 0.8 mm at the initial stage and the final stage, respectively. The radius of the stylus tip was 2 μm, and the measurement pressure was 0.75 mN. By measuring after setting as described above, a measured value with respect to the maximum height roughness (Rmax) was obtained with reference to the value measured by a roughness meter manufactured by Mitutoyo.

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

2) Production of electrolytic solution A basic electrolytic solution was produced by dissolving LiPF ₆ , which is a solute, in a non-aqueous organic solvent in which ethylene carbonate (EC) and ethylene methyl carbonate (EMC) were mixed at a ratio of 1: 2. .. A 99.5% by weight basal electrolyte and 0.5% by weight succinic anhydride were mixed to produce a non-aqueous electrolyte.

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

4) Manufacture of lithium secondary battery for test A coin-shaped lithium secondary battery is provided by arranging a positive electrode and a negative electrode inside an aluminum can so as to be insulated from the aluminum can, and arranging a non-aqueous electrolyte solution and a separation membrane between them. Manufactured. Polypropylene (Celgard 2325; thickness 25 μm, average pore size φ28 nm, porosity 40%) was used as the separation membrane.

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

The copper foil slackened, wrinkled or torn during the manufacturing process of the copper foil and the lithium secondary battery according to Comparative Examples 1 to 6, but the copper foil was formed during the manufacturing process of the copper foil and the lithium secondary battery according to the manufacturing examples 1 to 6. No sagging, wrinkling or tearing occurred.

Specifically, in the process of manufacturing a lithium secondary battery using the following copper foil, the copper foil was sagging, wrinkled, or torn.

(1) Comparative Example 1 (wrinkle occurrence) in which the flow rate deviation exceeds 5% and the collective employment coefficient bias [TCB (220)] on the (220) plane exceeds 0.52;
(2) Comparative Example 2 (wrinkle generation) in which the concentration of 2-mercaptothiazolin (MTZ) in the electrolytic solution is less than 1 mg / L and the tensile strength is less than 29 kgf / mm ² .
(3) Comparative Example 3 (tear generation) in which the concentration of 2-mercaptothiazolin (MTZ) in the electrolytic solution exceeds 20 mg / L and the tensile strength exceeds 65 kgf / mm ² .
(4) Comparative Example 4 (cracking) in which the content of bis (3-sulfopropyl) disulfide (SPS) in the electrolytic solution is less than 2 mg / L and the average roughness profile element interval (Rsm) is less than 18 μm;
(5) Comparative Example 5 (wrinkle generation) in which the bis (3-sulfopropyl) disulfide (SPS) content in the electrolytic solution exceeds 21 mg / L and the roughness profile element average interval (Rsm) exceeds 148 μm;
(6) Comparative Example 6 (sagging) in which the content of polyethylene glycol (PEG) in the electrolytic solution exceeds 50 mg / L and the maximum height roughness (Rmax) is less than 0.6 μm.

It can be evaluated that the copper foil according to Comparative Examples 1 to 6 is 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 manufactured within the condition range according to the examples of the present invention, the copper foil was not torn during the copper foil manufacturing process or the lithium secondary battery manufacturing process using the copper foil, and the copper foil was formed. No sagging or wrinkles. Therefore, the copper foil according to the embodiment of the present invention has excellent roll-to-roll (RTR) processability and can be usefully used as a negative electrode current collector for a lithium secondary battery.

The present invention described above is not limited to the above-described Examples and the accompanying drawings, and the present invention states that various substitutions, modifications and changes can be made within the scope of the technical matters of the present invention. It will be obvious to those who have ordinary knowledge in the technical field to which they belong. Therefore, the scope of the present invention is limited by the claims described later, and it is interpreted that the scope of the present invention includes all forms of modification or modification derived from the meaning, scope and equivalent concept of the claims. There must be.

100, 200 Copper foil 210, 220 Anti-rust film 310 Active material layer 300, 400 Electrode for secondary battery 340 Negative electrode for secondary battery 370 Positive electrode for secondary battery MS matte surface SS shiny surface

Claims (12)

Contains a copper layer
Tensile strength of 29-65 kgf / mm ²
18-148 μm roughness profile element mean spacing (mean width of roofness profile elements) (Rsm),
0.52 The following texture coefficient bias [TCB (220)], and 0.6 2 [mu] m or more of the maximum height roughness (Rmax),
It is a copper foil that has
The texture coefficient bias [TCB (220)] is a copper foil calculated by the following (Equation 1).

Aggregate Coefficient Bias [TCB (220)] = TCmax-TCmin (Equation 1)

However, TCmax and TCmin in the above (Equation 1) are obtained from the texture coefficient [TC (220)] of the (220) plane of the copper foil.
The texture coefficient [TC (220)] of the (220) surface of the copper foil was measured three times at each of the left, center, and right points in the width direction of the copper foil, and was measured three times, respectively, on the left, center, and right sides. The average value of [TC (220)] at each point is calculated.
Of these average values, the highest average value is TCmax, and the lowest average value is TCmin. The copper foil according to claim 1, further comprising a rust preventive film arranged on the copper layer. The copper foil according to claim 2, wherein the rust preventive film contains at least one of chromium (Cr), a silane compound and a nitrogen compound. The copper foil according to claim 1, which has a weight deviation of 5% or less. The copper foil according to claim 1, which has an elongation rate of 2% or more at a room temperature of 25 ± 15 ° C. The copper foil according to claim 1, which has a thickness of 4 μm to 30 μm. The copper foil according to any one of claims 1 to 6, and an active material layer arranged on the copper foil.
Including electrodes for secondary batteries. Positive electrode (cathode),
A negative electrode (anode) arranged to face the positive electrode,
It contains an electrolyte that is disposed between the positive electrode and the negative electrode and provides an environment in which ions can move, and a separation membrane that electrically insulates the positive electrode and the negative electrode.
The negative electrode is
The copper foil according to any one of claims 1 to 6, and an active material layer arranged on the copper foil.
Including secondary batteries. The copper foil according to any one of claims 1 to 6, which is arranged on the polymer film and the polymer film.
Soft copper foil laminated film, including. The method for producing a copper foil according to any one of claims 1 to 6.
It includes a step of forming a copper layer by energizing a positive electrode plate and a rotating negative electrode drum arranged apart from each other in an electrolytic solution containing copper ions at a current density of 30 to 80 A / dm2.
The electrolytic solution is
While the temperature is maintained at 50-70 ° C,
70-100g / L copper ion,
80-130 g / L sulfuric acid,
2-20 mg / L 2-mercaptothiazoline,
2 to 20 mg / L bis (3-sulfopropyl) disulfide [bis- (3-sulfopropyl) disulfide] (SPS), and 50 mg / L or less polyethylene glycol (PEG),
Including methods. The method according to claim 10, wherein the electrolytic solution contains 10 to 30 mg / L of chlorine (Cl). The method according to claim 10, wherein the flow rate deviation per unit time (seconds, seconds) of the electrolytic solution is 5% or less.