KR20240078587A - Copper Foil, Electrode Comprising The Same, Secondary Battery Comprising The Same, and Method for Manufacturing The Same - Google Patents

Abstract

One embodiment of the present invention includes a copper film containing 99.9% by weight or more of copper; and a protective layer on the copper film, and has a tensile strength index of 3.0 kgf/mm ² or less and an elongation index of 2.1% or less. The tensile strength index is calculated by the following equation 1, [Equation 1] tensile strength index = | tensile strength 2 - tensile strength 1 | tensile strength 1 in the above equation 1 is the tensile strength of the sample before the salt spray test, and the above equation 1 The tensile strength 2 of is the tensile strength of the sample after the salt spray test, and the elongation index is calculated by the following equation 2, [Equation 2] Elongation index = | Elongation 2 - Elongation 1 | Elongation 1 in Equation 2 is the salt spray test. This is the elongation rate of the entire sample, and elongation rate 2 in Equation 2 is the elongation rate of the sample after the salt spray test. The soft water spray test is conducted in 6 cycles with 5±1% NaCl for a total of 72 hours, and 1 cycle is 35±2°C. This means spraying for 2 hours at a temperature and then drying for 10 hours.

Description

Copper foil, electrode containing the same, secondary battery containing the same, and method for manufacturing the same {Copper Foil, Electrode Comprising The Same, Secondary Battery Comprising The Same, and Method for Manufacturing The Same}

The present invention relates to copper foil, an electrode containing it, a secondary battery containing it, and a method of manufacturing the same.

A secondary battery is a type of energy conversion device that generates electricity by converting electrical energy into chemical energy, storing it, and then converting the chemical energy back into electrical energy when electricity is needed. It is used in portable home appliances such as mobile phones and laptops, as well as electric vehicles. It is used as an energy source. Secondary batteries are also referred to as rechargeable batteries because they can be recharged.

Secondary batteries that have economical and environmental advantages over disposable primary batteries include lead acid batteries, nickel cadmium secondary batteries, nickel hydride secondary batteries, and lithium secondary batteries.

In particular, lithium secondary batteries can store a relatively large amount of energy relative to their size and weight compared to other secondary batteries. Therefore, lithium secondary batteries are preferred in the field of information and communication devices where portability and mobility are important, and their application range is also expanding to energy storage devices for hybrid vehicles and electric vehicles.

Lithium secondary batteries are used repeatedly through charging and discharging in one cycle. When operating a device with a fully charged lithium secondary battery, the lithium ion secondary battery must have a high charge/discharge capacity in order to increase the operation time of the device. Therefore, research is continuously required to meet consumers' ever-increasing expectations (needs) regarding the charge/discharge capacity of lithium secondary batteries.

These secondary batteries include a negative electrode current collector made of copper foil. Among copper foils, electrolytic copper foil is widely used as a negative electrode current collector for secondary batteries. As the acceptance of secondary batteries increases and the demand for high-capacity, high-efficiency, and high-quality secondary batteries increases, electrolytic copper foil that can improve the characteristics of secondary batteries is required. In particular, there is a demand for electrolytic copper foil that can increase the capacity of secondary batteries and ensure stable capacity maintenance and performance.

Meanwhile, as the thickness of the copper foil increases, the amount of active material that can be contained in the same space increases, and the number of current collectors can increase, thereby increasing the capacity of the secondary battery. However, the thinner the copper foil is, the more curls occur, which causes defects such as tears or wrinkles in the copper foil due to curling of the edges when winding the copper foil, so it is in the form of a very thin film. There are difficulties in manufacturing copper foil. Therefore, in order to manufacture copper foil having a very thin thickness, curling of the copper foil must be prevented.

Accordingly, the present invention relates to copper foil, an electrode containing the same, a secondary battery containing the same, and a manufacturing method thereof that can prevent problems caused by the limitations and disadvantages of the related technology as described above.

One embodiment of the present invention provides a copper foil that does not curl, wrinkle, or tear even after a salt spray test by having a tensile strength index of 3.0 kgf/mm ² or less.

One embodiment of the present invention provides a copper foil that does not curl, wrinkle or tear even after a salt spray test by having an elongation index of 2.1% or less.

Another embodiment of the present invention seeks to provide an electrode for a secondary battery including such copper foil, and a secondary battery including the electrode for such a secondary battery.

Another embodiment of the present invention seeks to provide a method of manufacturing copper foil that prevents curling, wrinkling, or tearing.

In addition to the aspects of the present invention mentioned above, other features and advantages of the present invention will be described below, or may be clearly understood by those skilled in the art from such description.

One embodiment of the present invention includes a copper film containing 99.9% by weight or more of copper; and a protective layer on the copper film, and has a tensile strength index of 3.0 kgf/mm ² or less and an elongation index of 2.1% or less. The tensile strength index is calculated by the following equation 1, [Equation 1] tensile strength index = | tensile strength 2 - tensile strength 1 | tensile strength 1 in the above equation 1 is the tensile strength of the sample before the salt spray test, and the above equation 1 The tensile strength 2 of is the tensile strength of the sample after the salt spray test, and the elongation index is calculated by the following equation 2, [Equation 2] Elongation index = | Elongation 2 - Elongation 1 | Elongation 1 in Equation 2 is the salt spray test. This is the elongation rate of the entire sample, and elongation rate 2 in Equation 2 is the elongation rate of the sample after the salt spray test. The soft water spray test is conducted in 6 cycles with 5±1% NaCl for a total of 72 hours, and 1 cycle is 35±2°C. This means spraying for 2 hours at a temperature and then drying for 10 hours.

Another embodiment of the present invention includes preparing an electrolyte solution containing copper ions; forming a copper film; and forming a protective layer on the copper film, wherein the step of forming the copper film includes forming a copper film on the rotating cathode drum by energizing the positive electrode plate and the rotating cathode drum spaced apart from each other in the electrolyte solution in the electrolytic cell. It includes the step of forming, wherein the electrolyte solution contains 70 to 100 g/L of copper ions; 70 to 150 g/L sulfuric acid; 15 to 25 ppm chlorine (Cl); 1 to 100 ppm of lead ions (Pb ²⁺ ); 0.5 to 5 ppm arsenic (As); Silver (Ag) below 3 ppm; 1 to 10 ml/L of hydrogen peroxide; and an organic additive; wherein the organic additive includes at least one of a brightener (component A), a reducer (component B), and a roughness control agent (component C), and the brightener (component A) is sulfonic acid or a metal salt thereof. The aim is to provide a method for manufacturing copper foil, wherein the moderator (component B) includes a nonionic water-soluble polymer, and the roughness regulator (component C) includes a nitrogen-containing heterocyclic quaternary ammonium salt or a derivative thereof.

According to another embodiment of the present invention, copper foil; and an active material layer disposed on at least one surface of the copper foil.

According to another embodiment of the present invention, a cathode that provides lithium ions when charging; A cathode (anode) that provides electrons and lithium ions during discharge; an electrolyte disposed between the anode and the cathode to provide an environment in which lithium ions can move; and a separator that electrically insulates the positive electrode and the negative electrode.

According to the present invention, the occurrence of wrinkles or tears during the manufacturing process of copper foil is prevented, and the occurrence of wrinkles or tears is prevented or controlled even after a salt spray test. Using this copper foil, flexible printed circuit boards (FPCB), secondary batteries, etc. By manufacturing intermediate parts and final products, the productivity of the intermediate parts as well as final products can be improved.

1 is a cross-sectional view of a copper foil according to an embodiment of the present invention.
Figure 2 is a cross-sectional view of copper foil according to another embodiment of the present invention.
Figure 3 is a photograph of copper foil after a salt spray test according to another embodiment of the present invention.
Figure 4 is a cross-sectional view of an electrode for a secondary battery according to another embodiment of the present invention.
Figure 5 is a cross-sectional view of an electrode for a secondary battery according to another embodiment of the present invention.
Figure 6 is a schematic cross-sectional view of a secondary battery according to another embodiment of the present invention.
Figure 7 shows an apparatus for manufacturing copper foil according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. However, the embodiments described below are provided for illustrative purposes only to facilitate a clear understanding of the present invention, and do not limit the scope of the present invention.

The shape, size, ratio, angle, number, etc. shown in the drawings for explaining embodiments of the present invention are illustrative, and the present invention is not limited to the matters shown in the drawings. Like components may be referred to by the same reference numerals throughout the specification. In describing the present invention, if it is determined that a detailed description of related known technology may unnecessarily obscure the gist of the present invention, the detailed description is omitted.

When 'includes', 'has', 'consists of', etc. mentioned in this specification are used, other parts may be added unless the expression 'only' is used. If a component is expressed in the singular, the plural is included unless specifically stated. In addition, when interpreting components, it is interpreted to include the margin of error even if there is no separate explicit description.

In the case of a description of a positional relationship, for example, if the positional relationship of two parts is described as 'on top', 'on the top', 'on the bottom', 'next to', etc., 'immediately' Alternatively, one or more other parts may be placed between the two parts, unless the expression 'directly' is used.

Spatially relative terms such as “below, beneath,” “lower,” “above,” and “upper” refer to one element or component as shown in the drawing. It can be used to easily describe the correlation with other elements or components. Spatially relative terms should be understood as terms that include different directions of the element during use or operation in addition to the direction shown in the drawings. For example, if an element shown in the drawings is turned over, an element described as “below” or “beneath” another element may be placed “above” the other element. Accordingly, the illustrative term “down” may include both downward and upward directions. Likewise, the illustrative terms “up” or “on” can include both up and down directions.

In the case of a description of a temporal relationship, for example, if a temporal relationship is described as 'after', 'successfully after', 'after', 'before', etc., 'immediately' or 'directly' Unless the expression is used, non-continuous cases may also be included.

Although first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are merely used to distinguish one component from another. Accordingly, the first component mentioned below may also be the second component within the technical spirit of the present invention.

The term “at least one” should be understood to include all possible combinations from one or more related items. For example, “at least one of the first, second, and third items” means each of the first, second, or third items, as well as two of the first, second, and third items. It can mean a combination of all items that can be presented from more than one.

Each feature of the various embodiments of the present invention can be combined or combined with each other, partially or entirely, and various technological interconnections and operations are possible, and each embodiment may be implemented independently of each other or may be implemented together in a related relationship. It may be possible.

Figure 1 is a cross-sectional view of copper foil 110 according to an embodiment of the present invention.

Referring to FIG. 1, the copper foil 110 of the present invention includes a copper film 111 containing 99.9% by weight or more of copper and a protective layer 112 on the copper film 111. In the copper foil 110 shown in FIG. 1, the protective layer 112 is formed on one surface of the copper film 111, but embodiments of the present invention are not limited thereto. Referring to FIG. 2, a protective layer 112 may be formed on both sides of the copper film 111.

The copper film 111 may be formed on a rotating cathode drum through electroplating, and may have a shiny side that directly contacts the rotating cathode drum during the electroplating process and a matte side on the opposite side.

The protective layer 112 is formed by electrodepositing an anticorrosion material on the copper film 111. The rust preventive material may include at least one of a chromium compound, a silane compound, and a nitrogen compound. The protective layer 112 prevents oxidation and corrosion of the copper film 111 and improves heat resistance, thereby extending the lifespan of the copper foil 110 itself as well as the lifespan of the final product containing it.

According to one embodiment of the present invention, the copper foil 110 has a tensile strength index of 3.0 kgf/mm ² or less. The tensile strength index can be obtained by calculating according to Equation 1 below through tensile strength 1 and tensile strength 2. If the tensile strength index is 3.0 kgf/mm ² or less, the occurrence of wrinkles or tears can be prevented during the manufacturing process of copper foil, and the occurrence of wrinkles or tears can be prevented or controlled even after the salt spray test.

[Equation 1]

Tensile strength index = ｜Tensile strength 2 - Tensile strength 1｜

Tensile strength 1 in Equation 1 refers to the tensile strength of the sample before the salt spray test, and tensile strength 2 in Equation 1 refers to the tensile strength of the sample after the salt spray test.

At this time, the salt spray test is conducted in 6 cycles for a total of 72 hours using 5±1% NaCl on each copper foil. 1 cycle involves spraying at a temperature of 35±2℃ for 2 hours, and then spraying the sprayed sample for 10 hours. This means drying for a while.

On the other hand, when the tensile strength index of the copper foil 110 is greater than 3.0 kgf/mm ² , during the salt spray test on the copper foil 110, the change in tensile strength of the copper foil 110 before and after the salt spray test increases, so the salt spray test Wrinkles or tears may occur in the copper foil 110, which may reduce workability and increase the defect rate of the secondary battery.

According to one embodiment of the present invention, the copper foil 110 has an elongation index of 2.1% or less. The elongation index can be obtained by calculating according to Equation 2 below through elongation rate 1 and elongation rate 2. If the elongation index is 2.1% or less, the occurrence of wrinkles or tears can be prevented during the manufacturing process of copper foil, and the occurrence of wrinkles or tears can be prevented or controlled even after the salt spray test.

[Equation 2]

Elongation index = ｜Elongation 2 – Elongation 1｜

Elongation 1 in Equation 2 refers to the elongation of the sample before the salt spray test, and elongation 2 in Equation 2 refers to the elongation of the sample after the salt spray test.

At this time, the salt spray test is conducted in 6 cycles for a total of 72 hours using 5±1% NaCl on each copper foil. 1 cycle involves spraying at a temperature of 35±2℃ for 2 hours, and then spraying the sprayed sample for 10 hours. This means drying for a while.

On the other hand, when the elongation index of the copper foil 110 is more than 2.1%, during the salt spray test on the copper foil 110, the change in elongation of the copper foil 110 before and after the salt spray test increases, so the copper foil 110 after the salt spray test Wrinkles or tears may occur, which may reduce workability and increase the defect rate of secondary batteries.

Copper foil 110 according to an embodiment of the present invention has a thickness of 4 to 35 ㎛. When copper foil 110 is used as a current collector for an electrode in a secondary battery, the thinner the copper foil 110 is, the more current collectors can be accommodated in the same space, which is advantageous for increasing the capacity of the secondary battery. However, manufacturing copper foil 110 with a thickness of less than 4 μm causes a decrease in workability.

On the other hand, when a secondary battery is manufactured with copper foil 110 exceeding 35 ㎛, it becomes difficult to implement high capacity due to the thick copper foil 110.

Copper foil 110 according to an embodiment of the present invention may have a tensile strength 2 of 28 kg/mm2 or more. Tensile strength 2 according to one embodiment of the present invention is the tensile strength of the sample after the salt spray test. In order to suppress wrinkles and tears of the copper foil 110 after the salt spray test, the copper foil 110 of the present invention has a high tensile strength 2 of 28 kg/mm ² or more. If the tensile strength of the copper foil 110 after the salt spray test is less than 28 kg/mm ² , folding of the copper foil 110 may occur between two adjacent rolls during the roll-to-roll manufacturing process, or the copper foil 110 may be damaged during the roll-to-roll manufacturing process. Wrinkles appear on the left and right extremities of the skin.

Copper foil 110 according to an embodiment of the present invention may have an elongation 2 of 3.0 to 12%. Elongation 2 according to one embodiment of the present invention is the elongation of the sample after the salt spray test. In order to suppress wrinkles and tears of the copper foil 110 after the salt spray test, the copper foil 110 of the present invention has an elongation 2 of 3.0 to 12%.

If the elongation of the copper foil 110 after the salt spray test is less than 3%, when the copper foil 110 is used as a current collector for a secondary battery, the copper foil 110 may not be sufficiently stretched in response to the large volume expansion of the high-capacity active material and may be torn. The risk is high.

On the other hand, if the elongation of the copper foil 110 after the salt spray test is more than 12%, the copper foil 110 may easily stretch during the secondary battery electrode manufacturing process, causing deformation of the electrode.

According to one embodiment of the present invention, the copper foil 110 may have an arithmetic average roughness (Ra) of 0.1 to 0.3 ㎛.

As charging and discharging of the secondary battery is repeated, contraction and expansion of the active material layer occur alternately, which causes separation of the active material layer and the copper foil 110, thereby lowering the charging and discharging efficiency of the secondary battery. Therefore, in order for the secondary electrode to secure a capacity retention rate and lifespan above a certain level (i.e., to suppress a decrease in charging and discharging efficiency of the secondary battery), the copper foil 110 has excellent coating properties with respect to the active material. The adhesive strength of the active material layer must be high.

Specifically, the smaller the arithmetic mean roughness (Ra) of the copper foil 110, the less the charge/discharge efficiency of the secondary battery including the copper foil 110 tends to decrease. Therefore, according to one embodiment of the present invention, the copper foil 110 has an arithmetic average roughness (Ra) of 0.1 to 0.3 ㎛.

When the arithmetic average roughness (Ra) of the copper foil 110 is less than 0.1㎛, the surface area of the copper foil 110 is relatively small, so the active material is easily separated from the copper foil 110, and as a result, the secondary battery is damaged due to repeated charging and discharging. This causes a rapid decrease in lifespan.

On the other hand, when the arithmetic average roughness (Ra) of the copper foil 110 is more than 0.3㎛, the uniformity of contact between the copper foil 110 and the active material layer does not reach a certain level, resulting in a large number of spaces between the copper foil 110 and the active material layer. exist (i.e., the coating itself is partially not completed), and as a result, the lifespan of the secondary battery is drastically reduced due to repeated charging and discharging.

Figure 3 is a photograph of copper foil after a salt spray test according to another embodiment of the present invention.

Below, the electrode 100 including the copper foil 110 of the present invention and the secondary battery including the electrode 100 will be described in detail.

Figure 4 is a cross-sectional view of an electrode for a secondary battery according to an embodiment of the present invention.

As illustrated in FIG. 4, the electrode 100 for a secondary battery according to an embodiment of the present invention includes the copper foil 110 and the active material layer 120 of any one of the above-described embodiments of the present invention.

FIG. 4 shows a configuration in which the active material layer 120 is formed on one side of the copper foil 110. However, the present invention is not limited to this in one embodiment, and referring to FIG. 5, the active material layer 120 may be formed on both sides of the copper foil 110.

In a lithium secondary battery, aluminum foil is generally used as a positive electrode current collector combined with the positive electrode active material, and copper foil 110 is generally used as a negative electrode current collector combined with the negative electrode active material.

According to one embodiment of the present invention, the electrode 100 for a secondary battery is a negative electrode, the copper foil 110 is used as a negative electrode current collector, and the active material layer 120 includes a negative electrode active material.

In order to ensure high capacity of the secondary battery, the active material layer 120 of the present invention may be formed of a composite of carbon and metal. The metal may include, for example, at least one of Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni, and Fe, preferably Si and/or Sn.

Figure 6 is a schematic cross-sectional view of a secondary battery according to an embodiment of the present invention.

Referring to FIG. 6, the secondary battery includes a cathode 370, a cathode 340, and an electrolyte disposed between the anode 370 and the cathode 340 to provide an environment in which ions can move. It includes an electrolyte (350), and a separator (360) that electrically insulates the anode (370) and the cathode (340). Here, the ions moving between the anode 370 and the cathode 340 are, for example, lithium ions. The separator 360 separates the positive electrode 370 and the negative electrode 340 to prevent charges generated in one electrode from being wasted in vain by moving to the other electrode through the interior of the secondary battery 105. Referring to FIG. 6, the separator 360 is disposed within the electrolyte 350.

The positive electrode 370 includes a positive electrode current collector 371 and a positive electrode active material layer 372, and aluminum foil may be used as the positive electrode current collector 371.

The negative electrode 340 includes a negative electrode current collector 341 and a negative electrode active material layer 342, and copper foil 110 may be used as the negative electrode current collector 341.

According to one embodiment of the present invention, the copper foil 110 shown in Figure 1 or Figure 2 may be used as the negative electrode current collector 341. Additionally, the electrode 100 for a secondary battery shown in FIG. 4 or 5 may be used as the cathode 340 for the secondary battery shown in FIG. 6.

Hereinafter, the manufacturing method of the copper foil 110 of the present invention will be described in detail with reference to FIG. 7.

The method of manufacturing the electrolytic copper foil 110 of the present invention includes forming a copper film 111 and forming a protective layer 112 on the copper film 111.

In the method of the present invention, the copper film 111 is formed on the rotating cathode drum 40 by energizing the positive electrode plate 30 and the rotating cathode drum 40 spaced apart from each other in the electrolyte 20 in the electrolytic cell 10. Including forming steps.

As illustrated in FIG. 7 , the positive electrode plate 30 may include first and second positive electrode plates 31 and 32 that are electrically insulated from each other.

In the step of forming the copper film 111, a seed layer is formed by passing electricity between the first anode plate 31 and the rotating cathode drum 40, and then forming a seed layer by passing electricity between the second positive electrode plate 32 and the rotating cathode drum 40. It can be performed by growing the seed layer.

The current density provided by the first and second positive electrode plates 31 and 32, respectively, may be 30 to 130 ASD.

When the current density provided by the first and second positive electrode plates 31 and 32, respectively, is less than 30 ASD, the surface roughness of the copper foil 110 is low and the adhesion between the copper foil 110 and the active material layer 120 may not be sufficient. You can.

On the other hand, when the current density provided by the first and second positive electrode plates 31 and 32 respectively exceeds 130 ASD, the surface of the copper foil 110 is rough and the active material may not be coated smoothly.

The surface properties of the copper film 111 may vary depending on the degree of surface buffing or polishing of the rotating cathode drum 40. For example, the surface of the rotating cathode drum 40 may be polished with a polishing brush having a grit size of #800 to #3000.

During the process of forming the copper film 111, the electrolyte solution 20 is maintained at a temperature of 48 to 60°C. More specifically, the temperature of the electrolyte solution 20 may be maintained at 50°C or higher. At this time, the physical, chemical, and electrical properties of the copper film 111 can be controlled by adjusting the composition of the electrolyte solution 20.

According to one embodiment of the present invention, the electrolyte solution 20 contains 70 to 100 g/L of copper ions, 70 to 150 g/L of sulfuric acid, 15 to 25 ppm of chlorine (Cl), and 1 to 100 ppm of lead ions. (Pb ²⁺ ), 0.5 to 5 ppm of arsenic (As), 0.1 to 3 ppm of silver ions (Ag ⁺ ), 1 to 10 ml/L of hydrogen peroxide (H2O2), and organic additives.

In order to facilitate the formation of the copper film 111 by electrodeposition of copper, the copper ion concentration and the sulfuric acid concentration in the electrolyte solution 20 are adjusted to 70 to 100 g/L and 70 to 150 g/L, respectively. .

In one embodiment of the present invention, chlorine (Cl) includes both a chlorine ion (Cl-) and a chlorine atom present in the molecule. Chlorine (Cl) may be used, for example, to remove silver (Ag) ions introduced into the electrolyte solution 20 during the process of forming the copper film 111. Specifically, chlorine (Cl) can precipitate silver (Ag) ions in the form of silver chloride (AgCl). This silver chloride (AgCl) can be removed by filtration.

If the concentration of chlorine (Cl) is less than 15 ppm, removal of silver (Ag) ions does not occur smoothly. On the other hand, if the concentration of chlorine (Cl) exceeds 25 ppm, unnecessary reactions may occur due to excess chlorine (Cl). Accordingly, the chlorine (Cl) concentration in the electrolyte solution 20 is managed in the range of 15 to 25 ppm.

According to one embodiment of the present invention, the electrolyte solution 20 containing an organic additive may further include lead ions (Pb ²⁺ ). Specifically, the electrolyte solution 20 may contain 1 to 100 ppm of lead ions (Pb ²⁺ ). When the lead ion (Pb ²⁺ ) is maintained at 1 to 100 ppm, the tensile strength index according to the present invention may be maintained at 3.0 kgf/mm ² or less, and the elongation index may be maintained at 2.1 % or less. As a result, the occurrence of wrinkles or tears during the manufacturing process of copper foil can be prevented, and the occurrence of wrinkles or tears can be prevented or controlled even after the salt spray test. On the other hand, when the concentration of lead ions (Pb ²⁺ ) is less than 1 ppm, a problem may occur in which the effectiveness of the present invention is reduced in terms of maintaining its physical properties. As a result, the tensile strength after the salt spray test was drastically lower than before the salt spray test, causing a problem in which the tensile strength index became greater than 3.0 kgf/mm ² , and the elongation rate after the salt spray test was drastically lower than before the salt spray test, resulting in an elongation index of 2.1%. A bigger problem arises.

In addition, when the concentration of lead ions (Pb ²⁺ ) exceeds 100ppm, copper is precipitated unevenly, and as a result, the tensile strength after the salt spray test is drastically lower than before the salt spray test, resulting in a tensile strength index lower than 3.0 kgf/mm ² A problem occurs, and after the salt spray test, the elongation rate drops drastically compared to before the salt spray test, causing the elongation index to become greater than 2.1%.

According to one embodiment of the present invention, the electrolyte solution 20 containing an organic additive may further include arsenic (As). Specifically, the electrolyte solution 20 may contain 0.5 to 5 ppm of arsenic (As). When arsenic (As) is maintained at 0.5 to 5 ppm, the tensile strength index according to the present invention can be maintained at 3.0 kgf/mm ² or less, and the elongation index can be maintained at 2.1% or less. In addition, arsenic (As) acts as an accelerator to promote the reduction reaction of copper (Cu) in a certain concentration range. However, in the electrolyte solution 20, arsenic (As) may exist, for example, in a trivalent or pentavalent ionic state (As ³⁺ , As ⁵⁺ ).

On the other hand, when the concentration of arsenic (As) is less than 0.5 ppm, the reduction reaction of copper decreases, and as a result, the tensile strength after the salt spray test is drastically lower than before the salt spray test, causing the tensile strength index to become greater than 3.0 kgf/mm ^2. occurs, and after the salt spray test, the elongation rate drops drastically compared to before the salt spray test, causing a problem where the elongation index becomes greater than 2.1%.

In addition, when the concentration of arsenic (As) exceeds 5 ppm, the reduction reaction of copper occurs excessively, and as a result, the tensile strength after the salt spray test is drastically lower than before the salt spray test, resulting in a tensile strength index of 3.0 kgf/mm ² A problem occurs in which the elongation becomes larger, and after the salt spray test, the elongation rate drops drastically compared to before the salt spray test, causing the elongation index to become greater than 2.1%.

Additionally, according to an embodiment of the present invention, the electrolyte solution 20 containing an organic additive may further include silver (Ag). Specifically, the electrolyte solution 20 may contain 0.1 to 3 ppm of silver (Ag). When silver (Ag) is maintained at 0.1 to 3 ppm, the tensile strength index according to the present invention can be maintained at 3.0 kgf/mm ² or less, and the elongation index can be maintained at 2.1% or less.

On the other hand, if the concentration of silver (Ag) is less than 0.1 ppm, the elongation rate after the salt spray test is drastically lower than before the salt spray test, resulting in a problem in which the elongation index becomes greater than 2.1%.

In addition, when the concentration of silver (Ag) is more than 3 ppm, the tensile strength after the salt spray test is drastically lower than before the salt spray test, resulting in a problem in which the tensile strength index becomes greater than 3.0 kgf/mm ² .

According to one embodiment of the present invention, the electrolyte solution 20 containing an organic additive may further include hydrogen peroxide (H2O2). Organic impurities are present in the electrolyte solution 20 for continuous plating due to organic additives. By treating with hydrogen peroxide (H2O2), the organic impurities can be decomposed and the carbon (C) content inside the copper foil can be appropriately adjusted. As the TOC concentration in the electrolyte solution 20 increases, the amount of carbon (C) element flowing into the copper film 111 increases, and accordingly, the total amount of elements released from the copper film 111 during heat treatment increases, resulting in an increase in the amount of carbon (C) element flowing into the copper film 111. This causes the strength of (110) to decrease.

The amount of hydrogen peroxide (H ₂ O ₂ ) added is 1 to 10 ml of hydrogen peroxide (H ₂ O ₂ ) per L of electrolyte. Specifically, it is preferable to add 2 to 8 ml of hydrogen peroxide (H2O2) per L of electrolyte solution. If the amount of hydrogen peroxide (H2O2) added is less than 1 ml/L, it is meaningless because there is almost no effect on decomposing organic impurities. When the amount of hydrogen peroxide (H2O2) added exceeds 10 ml/L, organic impurities are excessively decomposed, and the effects of organic additives such as brighteners, reducers, and roughness control agents are suppressed.

The organic additive contained in the electrolyte solution 20 includes at least one of a brightener (component A), a reducer (component B), and a roughness regulator (component C). The organic additive in the electrolyte solution 20 has a concentration of 1 to 100 ppm.

The organic additive may include two or more of a brightener (component A), a reducer (component B), and a roughness control agent (component C), or may include all three components. Even in this case, the concentration of organic additives is 100 ppm or less. If the organic additive includes all a brightener (component A), a reducer (component B), and a roughness control agent (component C), the organic additive may have a concentration of 10 to 100 ppm.

The brightener (component A) contains sulfonic acid or a metal salt thereof. The brightener (component A) may have a concentration of 1 to 15 ppm in the electrolyte solution 20.

The brightener (component A) increases the amount of charge in the electrolyte 20, thereby increasing the electrodeposition rate of copper, improving the curl characteristics of the copper foil, and enhancing the gloss of the copper foil 110. If the concentration of the brightener (component A) is less than 1 ppm, the gloss of the copper foil 110 may decrease, and if it exceeds 15 ppm, the roughness of the copper foil 110 may increase and the strength may decrease. As a result, after the salt spray test, The tensile strength drops dramatically compared to before the salt spray test, causing a problem in which the tensile strength index becomes greater than 3.0 kgf/mm ² .

More specifically, the brightener (component A) may have a concentration of 5 to 10 ppm in the electrolyte solution 20.

Brightening agents include, for example, bis-(3-sulfopropyl)-disulfide disodium salt, 3-mercapto-1-propanesulfonic acid, 3-(N,N-dimethylthiocarbamoyl)-thiopropanesulfonate sodium salt. , 3-[(amino-iminomethyl)thio]-1-propanesulfonate sodium salt, o-ethyldithiocarbonato-S-(3-sulfopropyl)-ester sodium salt, 3-(benzothiazolyl- It may include at least one of 2-mercapto)-propyl-sulfonic acid sodium salt and ethylenedithiiodipropylsulfonic acid sodium salt.

The moderator (component B) contains a nonionic water-soluble polymer. The moderator (component B) may have a concentration of 1 to 15 ppm in the electrolyte solution 20.

The moderator (component B) reduces the electrodeposition rate of copper and prevents a rapid increase in roughness and a decrease in strength of the copper foil 110. This moderator (component B) is also called an inhibitor or suppressor.

If the concentration of the moderator (component B) is less than 1 ppm, the roughness of the copper foil 110 increases rapidly, and a problem may occur where the strength of the copper foil 110 decreases. As a result, the tensile strength after the salt spray test may decrease. It drops dramatically compared to before the salt spray test, causing the problem that the tensile strength index becomes greater than 3.0 kgf/mm ² . On the other hand, even if the concentration of the moderator (component B) exceeds 15 ppm, there is little change in the physical properties of the copper foil 110, such as appearance, gloss, roughness, strength, and elongation. Therefore, the concentration of the moderator (component B) can be adjusted to a range of 1 to 15 ppm without the need to increase the manufacturing cost and waste raw materials by unnecessarily increasing the concentration of the moderator (component B).

The moderator (component B) is, for example, polyethylene glycol (PEG), polypropylene glycol, polyethylenepolypropylene copolymer, polyglycerin, polyethylene glycol dimethyl ether, hydroxyethylenecellulose, polyvinyl alcohol, stearic acid polyglycol. It may include at least one nonionic water-soluble polymer selected from ethers and stearyl alcohol polyglycol ethers. However, the type of moderator is not limited to this, and other nonionic water-soluble polymers that can be used in the production of the high-strength copper foil 110 can be used as a moderator.

The roughness regulator (component C) contains a nitrogen-containing heterocyclic quaternary ammonium salt or a derivative thereof.

The roughness control agent (component C) improves the gloss and flatness of the copper foil 110. The roughness control agent (component C) may have a concentration of 1 to 15 ppm in the electrolyte solution 20.

If the concentration of the roughness control agent (component C) is less than 1 ppm, the effect of improving the gloss and flatness of the copper foil 110 does not appear, and at the same time, the elongation after the salt spray test decreases sharply compared to before the salt spray test, so that the elongation index becomes greater than 2.1%. A problem arises. On the other hand, when the concentration of the roughness control agent (component C) exceeds 15 ppm, there is a problem that the surface gloss of the copper foil 110 becomes non-uniform and the surface roughness increases rapidly, and it is difficult to secure the desired roughness range. As a result, the strength of the copper foil 110 may decrease, and as a result, the tensile strength after the salt spray test is drastically lower than before the salt spray test, resulting in a problem in which the tensile strength index becomes greater than 3.0 kgf/mm ² . More specifically, the roughness control agent (component C) may have a concentration of 5 to 10 ppm in the electrolyte solution 20.

The roughness control agent (component C) may include at least one of the compounds represented by the following formulas 1 to 5.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

In Formulas 1 to 5, ℓ1 to ℓ4, m1 to m4, and n1 to n5 each represent a repeating unit, are integers of 1 or more, and may be the same or different from each other.

According to one embodiment of the present invention, the compounds represented by Formulas 1 to 5 each have a number average molecular weight of 500 to 12,000.

When the number average molecular weight of the compounds represented by Formulas 1 to 5 used as a roughness control agent is less than 500, the surface roughness of the copper foil 110 increases because the ratio of monomers is high. If the content of the roughness control agent is small, the surface roughness of the copper film 111 may increase and glossiness and flatness may decrease.

If the number average molecular weight of the compounds represented by Formulas 1 to 5 exceeds 12,000, the variation in surface roughness of the copper foil 110 increases. In this case, even if the concentration of other additives is adjusted, it is difficult to suppress the increase in variation in surface roughness of the copper foil 110.

Compounds represented by Chemical Formulas 1 to 5 can be made by polymerization or copolymerization using, for example, DDAC (Diallyl dimethyl ammoniumchloride).

Compounds represented by Formula 1 include, for example, PAS-2451 (Mw 30,000, Nittobo).

Compounds represented by Formula 2 include, for example, PAS-84 (Mw 20,000, Nittobo).

Compounds represented by Formula 3 include, for example, PAS-2351 (Mw 25,000, Nittobo).

Compounds represented by Formula 4 include, for example, PAS-A-1 (Mw 5,000, Nittobo), PAS-A-5 (Mw 4,000, Nittobo), etc.

Compounds represented by Formula 5 include, for example, PAS-J-81 (Mw 180,000, Nittobo).

When the copper film 111 is formed, the flow rate of the electrolyte solution 20 supplied into the electrolytic cell 10 may be 41 to 45 m3/hour.

The step of forming the copper film 111 includes filtering the electrolyte solution 20 using activated carbon, filtering the electrolyte solution 20 using diatomaceous earth, and treating the electrolyte solution 20 with ozone (O3). It may include at least one of the steps.

Specifically, for filtration of the electrolyte solution 20, the electrolyte solution 20 may be circulated at a flow rate of 35 to 45 m3/hour. That is, in order to remove solid impurities present in the electrolyte 20 while electroplating to form the copper film 111 is performed, filtration may be performed at a flow rate of 35 to 45 m3/hour. At this time, activated carbon or diatomaceous earth may be used.

In order to maintain the cleanliness of the electrolyte 20, the electrolyte 20 may be treated with ozone (O3).

Additionally, in order to ensure the cleanliness of the electrolyte 20, the copper wire (Cu wire), which is a raw material of the electrolyte 20, may be cleaned.

According to one embodiment of the present invention, the steps of preparing the electrolyte 20 include heat-treating the copper wire, pickling the heat-treated copper wire, washing the pickled copper wire, and placing the washed copper wire in the electrolyte solution. It may include the step of adding sulfuric acid.

More specifically, in order to maintain the cleanliness of the electrolyte 20, high purity (99.9% or more) copper wire (Cu wire) is heat treated in an electric furnace at 750°C to 850°C to burn off various organic impurities on the copper wire. , Copper for producing the electrolyte solution 20 can be manufactured by sequentially going through the process of pickling the heat-treated copper wire for 10 to 20 minutes using a 10% sulfuric acid solution and washing the pickled copper wire with distilled water. The electrolyte solution 20 can be prepared by combining the washed copper wire with sulfuric acid for electrolyte solution.

According to one embodiment of the present invention, in order to satisfy the characteristics of the copper foil 110, the concentration of total organic carbon (TOC) in the electrolyte solution 20 is managed to be 300 ppm or less. That is, the electrolyte solution 20 may have a total organic carbon (TOC) concentration of 300 ppm or less.

The copper film 111 manufactured in this way can be cleaned in a cleaning tank.

For example, acid cleaning to remove impurities on the surface of the copper film 111, such as resin components or natural oxide, and water cleaning to remove the acid solution used in the acid cleaning. ) can be performed sequentially. The cleaning process may be omitted.

Next, a protective layer 112 is formed on the copper film 111.

Referring to FIG. 7 , the step of immersing the copper film 111 in an anticorrosion solution 60 may be further included. When the copper film 111 is immersed in the rust preventive liquid 60, it may be guided by a guide roll 70 disposed in the rust preventive liquid 60.

As described above, the rust preventive liquid 60 may contain at least one of a chromium compound, a silane compound, and a nitrogen compound. For example, the copper film 111 may be immersed in a 1 to 10 g/L potassium dichromate solution at room temperature for 1 to 30 seconds.

Meanwhile, the protective layer 112 may include a silane compound obtained by silane treatment or a nitrogen compound obtained by nitrogen treatment.

Copper foil 110 is created by forming this protective layer 112.

On one or both sides of the copper foil 110 of the present invention manufactured through the above method, carbon; metal (Me) of Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe; an alloy containing the metal (Me); Oxide (MeOx) of the metal (Me); The electrode (i.e., negative electrode) for a secondary battery of the present invention can be manufactured by coating one or more negative electrode active materials selected from the group consisting of a composite of metal (Me) and carbon.

For example, 100 parts by weight of carbon for a negative electrode active material is mixed with 1 to 3 parts by weight of styrenebutadiene rubber (SBR) and 1 to 3 parts by weight of carboxymethyl cellulose (CMC), and then a slurry is prepared using distilled water as a solvent. . Next, the slurry is applied to a thickness of 20 to 60 μm on the electrolytic copper foil 110 using a doctor blade, and pressed at a temperature of 110 to 130° C. at a pressure of 0.5 to 1.5 ton/cm2.

A secondary battery can be manufactured using a conventional positive electrode, electrolyte, and separator along with the secondary battery electrode (negative electrode) of the present invention manufactured by the above method.

Below, the present invention will be described in detail through examples and comparative examples. However, the following examples are only intended to aid understanding of the present invention, and the scope of the present invention is not limited to these examples.

Examples 1-6 and Comparative Examples 1-8

Copper foil was manufactured using a making machine including an electrolytic cell 10, a rotating cathode drum 40 disposed in the electrolytic cell 10, and a positive electrode plate 30 disposed spaced apart from the rotating cathode drum 40. The electrolyte solution 20 is a copper sulfate solution. The concentration of copper ions in the electrolyte 20 was set to 87 g/L, the concentration of sulfuric acid was 110 g/L, the temperature of the electrolyte was set to 55°C, and the current density was set to 60ASD.

In addition, the concentration of chlorine (Cl) contained in the electrolyte solution 20 is maintained at 20 ppm, and the concentrations of lead ions, arsenic, silver ions, hydrogen peroxide, and organic additives are shown in Table 1 below.

Among the organic additives, bis-(3-sulfopropyl)-disulfide disodium salt (SPS) was used as a brightener (component A), polyethylene glycol (PEG) was used as a moderator (component B), and a roughness regulator (D Ingredient), triylmethylethylammonium ethyl sulfide maleic acid copolymer (PAS-2451TM, Nittobo, Mw. 30,000) was used.

A copper film 111 was manufactured by applying a current at a current density of 60 ASD between the rotating cathode drum 40 and the anode plate 30. Next, the copper foil 110 was manufactured by immersing the copper film 111 in a rust preventive solution for about 2 seconds and chromating the surface of the copper film 111 to form a protective layer 112. A rust preventive liquid containing chromic acid as the main ingredient was used, and the concentration of chromic acid was 5 g/L.

As a result, copper foils of Examples 1-6 and Comparative Examples 1-8 were manufactured.

SPS
(Component A)
(ppm) PEG
(B component)
(ppm) PAS-2451
(C component)
(ppm) Lead ion (Pb ²⁺ )
(ppm) Arsenic (As)
(ppm) Silver (Ag)
(ppm) hydrogen peroxide
(ml/L) Example 1 5 2 5 30 1.5 0.5 2 Example 2 10 4 7 30 1.6 0.7 5 Example 3 15 6 10 30 2.5 1.3 7 Example 4 10 8 12 50 3.5 2.3 7 Example 5 10 10 15 50 4.0 2.5 5 Example 6 10 13 10 70 4.1 2.8 5 Comparative Example 1 55 5 10 0.1 3.5 2.1 9 Comparative example 2 10 50 15 50 7.0 1.5 7 Comparative Example 3 15 7 55 50 3.7 0.01 5 Comparative example 4 0 10 10 150 7.5 5.5 5 Comparative Example 5 10 0 10 70 0.1 0.01 7 Comparative Example 6 10 10 0 150 0.2 7.0 5 Comparative example 7 0.8 12 12 50 0.1 1.3 5 Comparative example 8 12 0.8 12 50 8.0 1.5 5 Comparative Example 9 12 12 0.8 50 7.0 1.5 5

Tensile strength 1
(kgf/ ^mm2 ) Tensile strength 2
(kgf/ ^mm2 ) Tensile Strength Index
(kgf/ ^mm2 ) Elongation 1
(%) Elongation 2
(%) Elongation index
(%) Whether wrinkles/tearing occurred Example 1 32.0 29.1 2.9 11.5 10.8 0.7 doesn't exist Example 2 48.7 46.3 2.4 4.6 3.6 1.0 doesn't exist Example 3 53.3 51.7 1.6 4.2 3.1 1.1 doesn't exist Example 4 45.7 43.4 2.3 8.2 6.1 2.1 doesn't exist Example 5 51.3 48.7 2.6 5.4 4.2 1.2 doesn't exist Example 6 38.7 36.4 2.3 9.2 7.9 1.3 doesn't exist Comparative Example 1 38.4 35.2 3.2 6.8 3.8 3.0 generation Comparative example 2 31.7 28.4 3.3 5.8 3.2 2.6 generation Comparative Example 3 47.2 43.3 3.9 4.9 2.7 2.2 generation Comparative Example 4 51.0 47.6 3.4 5.2 3.2 2.0 generation Comparative Example 5 55.4 52.1 3.3 4.1 1.8 2.3 generation Comparative Example 6 49.0 45.4 3.6 4.8 2.1 2.7 generation Comparative Example 7 48.5 44.8 3.7 6.1 3.2 2.9 generation Comparative example 8 50.2 47.1 3.1 4.8 2.1 2.7 generation Comparative Example 9 51.8 47.9 3.9 5.2 2.4 2.8 generation

For the copper foils of Example 1-6 and Comparative Example 1-6 manufactured in this way, i) tensile strength 1, ii) tensile strength 2, iii) tensile strength index, iv) elongation 1, v) elongation 2, vi) Elongation index and vii) occurrence of wrinkles/tearing were checked. i) tensile strength 1, ii) tensile strength 2 were measured.

The tensile strength 1 of the copper foil 110 is the tensile strength of the sample before the salt spray test,

The tensile strength 2 of the copper foil 110 is the tensile strength of the sample after the salt spray test.

At this time, the salt spray test is conducted in 6 cycles for a total of 72 hours using 5±1% NaCl on each copper foil. 1 cycle involves spraying at a temperature of 35±2℃ for 2 hours, and then spraying the sprayed sample for 10 hours. This means drying for a while.

Tensile strength 1 was measured at room temperature using a universal testing machine (UTM) using the method specified in the IPC-TM-650 Test Method Manual.

For tensile strength 2, a salt spray test was performed on the copper foil 110, and the tensile strength was measured in the same manner as for tensile strength 1.

iii) Calculation of tensile strength index

The tensile strength index can be obtained by calculating the measured i) tensile strength 1 and ii) tensile strength 2 values according to Equation 1 below.

[Equation 1]

Tensile strength index = ｜Tensile strength 2 - Tensile strength 1｜

iv) Elongation 1, v) Elongation 2 measurements

The elongation rate 1 of the copper foil 110 is the elongation rate of the sample before the salt spray test,

Elongation 2 of copper foil 110 is the elongation of the sample after the salt spray test.

At this time, the salt spray test is conducted in 6 cycles for a total of 72 hours using 5±1% NaCl on each copper foil. 1 cycle involves spraying at a temperature of 35±2℃ for 2 hours, and then spraying the sprayed sample for 10 hours. This means drying for a while.

Elongation 1 was measured at room temperature using a Universal Testing Machine (UTM) using the method specified in the IPC-TM-650 Test Method Manual.

For elongation 2, a salt spray test was performed on the copper foil 110, and elongation 2 was measured in the same manner as for elongation 1.

vi) Calculation of elongation index

The elongation index can be obtained by calculating the measured i) elongation 1 and ii) elongation 2 values according to Equation 2 below.

[Equation 2]

Elongation index = ｜Elongation 2 – Elongation 1｜

vii) Whether or not there are wrinkles/tears

After charging and discharging 100 times, the secondary battery was disassembled and observed whether wrinkles or tears occurred in the copper foil. Cases where wrinkles or tears occurred in the copper foil were marked as “occurrence,” and cases where they did not occur were marked as “none.”

Referring to Table 1 and Table 2, you can see the following results.

Tears/wrinkles occurred in the copper foil of Comparative Example 1, which was manufactured with an electrolyte solution containing an excessive amount of brightener (component A) and a trace amount of lead ions.

Tears/wrinkles occurred in the copper foil of Comparative Example 2, which was manufactured with an electrolyte solution containing an excess amount of a moderator (component B) and arsenic.

Tears/wrinkles occurred in the copper foil of Comparative Example 3, which was manufactured with an electrolyte solution containing an excessive amount of a roughness regulator (component C) and a trace amount of silver (Ag).

Tears/wrinkles occurred in the copper foil of Comparative Example 4, which was manufactured with an electrolyte solution containing an excessive amount of lead ions, arsenic, and silver (Ag) but not containing a brightener (component A).

Tearing/wrinkling occurred in the copper foil of Comparative Example 5, which was manufactured with an electrolyte solution containing trace amounts of arsenic and silver (Ag) without containing a moderator (component B).

Tears/wrinkles occurred in the copper foil of Comparative Example 6, which was manufactured with an electrolyte solution that did not contain a roughness regulator (component C), contained an excessive amount of lead ions and silver (Ag), and contained a trace amount of arsenic.

Tears/wrinkles occurred in the copper foil of Comparative Example 7, which was manufactured with an electrolyte solution containing a brightener (component A) and a trace amount of arsenic (As).

Tears/wrinkles occurred in the copper foil of Comparative Example 8, which was manufactured with an electrolyte solution containing a trace amount of a moderator (component B) and an excessive amount of arsenic (As).

Tearing/wrinkling occurred in copper foil manufactured with an electrolyte solution containing a trace amount of a roughness regulator (component C) and an excessive amount of arsenic (As).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible without departing from the technical details of the present invention. It will be clear to a person with ordinary knowledge. Therefore, the scope of the present invention is expressed by the claims described later, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

100: Electrode for interest cell
110: copper foil
111: copper film
120: Active material layer
10: Electrolyzer
20: electrolyte

Claims (9)

A copper film containing 99.9% by weight or more of copper; and
It includes a protective layer on the copper film,
Has a tensile strength index of 3.0 kgf/mm ² or less,
Copper foil with an elongation index of 2.1% or less:
The tensile strength index is calculated using Equation 1 below,
[Equation 1]
Tensile strength index = ｜Tensile strength 2 - Tensile strength 1｜
Tensile strength 1 in Equation 1 is the tensile strength of the sample before the salt spray test,
Tensile strength 2 in Equation 1 is the tensile strength of the sample after the salt spray test,
The elongation index is calculated using Equation 2 below,
[Equation 2]
Elongation index = ｜Elongation 2 – Elongation 1｜
Elongation 1 in Equation 2 is the elongation of the sample before the salt spray test,
Elongation 2 in Equation 2 is the elongation of the sample after the salt spray test,
The soft water spray test is conducted in 6 cycles with 5±1% NaCl for a total of 72 hours.
1 cycle means spraying for 2 hours at a temperature of 35 ± 2℃, followed by drying for 10 hours. According to paragraph 1,
The tensile strength 2 is 28 kgf/mm ² or more. According to paragraph 1,
The elongation 2 is in the range of 3.0 to 12%. According to paragraph 1,
Copper foil further comprising a protective layer on the copper film. According to paragraph 4,
The protective layer includes at least one of a chromium compound, a silane compound, and a nitrogen compound. Preparing an electrolyte solution containing copper ions;
forming a copper film; and
Including forming a protective layer on the copper film,
The step of forming the copper film is,
Comprising the step of forming a copper film on the rotating cathode drum by energizing the positive electrode plate and the rotating cathode drum spaced apart from each other in the electrolyte solution in the electrolytic cell,
The electrolyte is,
70 to 100 g/L of copper ions;
70 to 150 g/L sulfuric acid;
15 to 25 ppm chlorine (Cl);
1 to 100 ppm of lead ions (Pb ²⁺ );
0.5 to 5 ppm arsenic (As);
0.1 to 3 ppm of silver ions (Ag ⁺ );
1 to 10 ml/L of hydrogen peroxide; and
Contains organic additives;
The organic additive includes at least one of a brightener (component A), a reducer (component B), and a roughness regulator (component C),
The polishing agent (component A) contains sulfonic acid or a metal salt thereof,
The moderator (component B) includes a nonionic water-soluble polymer,
The roughness regulator (component C) includes a nitrogen-containing heterocyclic quaternary ammonium salt or a derivative thereof,
Manufacturing method of copper foil. According to clause 6,
The method of producing copper foil, wherein the brightener (component A) has a content of 1 to 15 ppm. According to clause 6,
The method of producing copper foil, wherein the moderator (component B) has a content of 1 to 15 ppm. According to clause 6,
A method of manufacturing copper foil, wherein the roughness control agent has a content of 1 to 15 ppm.