KR20180080512A - Electrolytic Copper Foil with Optimized Peak Roughness, Electrode Comprising The Same, Secondary Battery Comprising The Same, and Method for Manufacturing The Same - Google Patents

Abstract

Disclosed are an electrolytic copper foil with optimized peak roughness, an electrode comprising the same, a secondary battery comprising the same, and a method for manufacturing the same such that a capacity maintenance of a secondary battery can be improved. The copper foil of the present invention includes a first surface and a second surface opposite to the first surface. Each peak roughness (Rp) of the first and second surfaces is 0.36-1.69μm, respectively, and a difference between the peak roughness (Rp) of the first surface and the peak roughness (Rp) of the second surface equals to or less than 0.6μm.

Description

TECHNICAL FIELD [0001] The present invention relates to an electrolytic copper foil having an optimized peak roughness, an electrode including the same, a secondary battery including the electrode, and a method of manufacturing the same. BACKGROUND ART }

The present invention relates to an electrolytic copper foil having an optimized peak roughness (Rp) for improving capacity maintenance of a secondary battery, an electrode including the same, a secondary battery including the same, and a method of manufacturing the same.

The secondary battery is a kind of energy conversion device that converts electric energy into chemical energy and stores it, and converts the chemical energy into electric energy when electricity is needed, thereby generating electricity. The secondary battery is a kind of energy conversion device, It is used as an energy source for automobiles.

Examples of secondary batteries that are more economical and environmentally advantageous than disposable primary batteries include lead acid batteries, nickel cadmium secondary batteries, nickel hydrogen secondary batteries, and lithium secondary batteries.

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

The lithium secondary battery is repeatedly used as one cycle of charging and discharging. When a certain fully charged lithium secondary battery is operated, the lithium ion secondary battery must have a high charging / discharging capacity in order to increase the operating time of the device. Therefore, there is a continuing need for research to satisfy the ever-increasing needs of consumers for the charging / discharging capacity of lithium secondary batteries.

As one method for increasing the capacity of a lithium secondary battery, it has been proposed to use a complex active material in which Si or Sn is added to a carbon active material as an active material applied on an electrolytic copper foil in the production of a negative electrode of a secondary battery. However, such a complex active material rapidly and severely expands due to heat generated when the lithium secondary battery is charged or discharged, causing breakage of the electrolytic copper foil. As the charging and discharging of the lithium secondary battery is repeated, contraction and expansion of the negative electrode active material occur alternately. This causes separation of the copper foil and the negative electrode active material, thereby lowering the charge / discharge capacity retention rate of the lithium secondary battery. In particular, as the bonding strength between the copper foil and the negative electrode active material is weak, the charge / discharge capacity retention rate of the lithium secondary battery is seriously degraded.

If the charging / discharging capacity of the secondary battery decreases sharply as the charge / discharge cycle is repeated (i.e., the capacity retention rate is low or the life is short), the consumer will need to frequently replace the secondary battery, Consumer inconvenience and waste of resources will result.

In order to increase the capacity of the lithium secondary battery, the thickness of the electrolytic copper foil used for manufacturing the negative electrode must be thin. However, as the thickness becomes thinner, the electrolytic copper foil becomes more susceptible to curl or wrinkle. Such bending or wrinkling of the electrolytic copper foil not only lowers the workability but also makes the active material coating itself impossible.

Accordingly, the present invention relates to an electrolytic copper foil capable of preventing problems caused by limitations and disadvantages of the related art, an electrode including the same, a secondary battery including the same, and a method of manufacturing the same.

One aspect of the present invention is to provide an electrolytic copper foil capable of securing a secondary battery having a high capacity retention rate.

Another aspect of the present invention is to provide an electrode capable of securing a secondary battery having a high capacity retention rate.

Another aspect of the present invention is to provide a secondary battery having a high capacity retention rate.

Another aspect of the present invention is to provide a method for producing a copper foil capable of securing a secondary battery having a high capacity retention rate.

Other features and advantages of the invention will be set forth in the description which follows, or may be learned by those skilled in the art from the description.

According to an aspect of the present invention, there is provided an electrolytic copper foil having a first surface and a second surface opposite to the first surface, the electrolytic copper foil having a matte surface facing the first surface and a shiny surface facing the second surface, A copper layer; A first protective layer on the mat surface; And a second protective layer on the shiny surface, wherein each of the first and second surfaces has a peak roughness (Rp) of 0.36 to 1.69 占 퐉, and the peak roughness of the first surface and the second surface Wherein the difference in peak roughness of the copper foil is 0.6 mu m or less.

Each of the first and second protective layers may include chromium (Cr), and the amount of chromium (Cr) deposited on each of the first and second surfaces may be 0.5 to 5.5 mg / m ² .

The difference between the chromium (Cr) deposition amount on the first surface and the chromium (Cr) deposition amount on the second surface may be 2.5 mg / m ² or less.

The surface roughness Rz of each of the first and second surfaces may be 2.5 탆 or less.

The electrolytic copper foil may have a yield strength of 21 to 58 kgf / mm ² at room temperature of 25 ± 15 ° C.

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

According to another aspect of the present invention, there is provided an electrolytic copper foil having a first side and a second side opposite to the first side; And a first active material layer on the first surface, the electrolytic copper foil comprising: a copper layer including a matte surface facing the first surface and a shiny surface facing the second surface; A first protective layer on the mat surface; And a second protective layer on the shiny surface, wherein each of the first and second surfaces has a peak roughness (Rp) of 0.36 to 1.69 占 퐉, and the peak roughness of the first surface and the second surface The difference in peak roughness of the secondary battery is 0.6 mu m or less.

Each of the first and second protective layers may include chromium (Cr), and the amount of chromium (Cr) deposited on each of the first and second surfaces may be 0.5 to 5.5 mg / m ² , The difference between the amount of chromium (Cr) deposited on one surface and the amount of deposited chromium (Cr) on the second surface may be 2.5 mg / m ² or less.

The electrolytic copper foil may have a yield strength of 21 to 58 kgf / mm ² at room temperature of 25 ± 15 ° C.

The electrode for a secondary battery may further include a second active material layer on the second surface, and the first and second active material layers may include carbon; A metal of Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe; An alloy comprising the metal; An oxide of the metal; And at least one active material selected from the group consisting of a complex of the metal and carbon.

According to another aspect of the present invention, there is provided a fuel cell comprising: a cathode; An anode comprising the electrode for the secondary battery; An electrolyte for providing an environment in which lithium ions can move between the anode and the cathode; And a separator that electrically isolates the anode and the cathode from each other.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a copper layer; And forming a protective layer on the copper layer, wherein the copper layer forming step comprises forming a copper layer comprising 50 to 100 g / L of copper ions, 50 to 150 g / L of sulfuric acid, 3 to 12 ppm of bis - (3-sulfopropyl) disulfide (SPS), and chlorine of 50 ppm or less; And performing electroplating by energizing the positive electrode plate and the rotating negative electrode disposed at a distance from each other in the electrolyte at a current density of 40 to 80 A / dm ² , wherein during the electroplating, The total concentration of scandium (Sc) and yttrium (Y) in the electrolytic solution is maintained at 350 mg / L or less and the surface of the rotating cathode drum is maintained at a concentration of 0.25 g / Wherein the abrasive grains are polished with an abrasive brush having a grain size (Grit) of 800 to < RTI ID = 0.0 ># 1500. ≪ / RTI >

The acidic electrolytic solution preparation step comprises: heat treating the copper wire at 600 to 900 DEG C for 30 to 60 minutes; Pickling the heat-treated copper wire; And injecting the pickled copper wire into sulfuric acid.

The copper layer forming step may further include the step of injecting hydrogen peroxide and air into the electrolytic solution while the electroplating is performed.

The electrolyte may further comprise at least one organic additive selected from the group consisting of hydroxyethyl cellulose (HEC), organic sulfide, organic nitride, glycol based polymer, and thiourea based compound.

The protective layer forming step may include immersing the copper layer in a rust preventive solution containing 0.5 to 1.5 g / L of Cr.

The foregoing general description of the present invention is intended to be illustrative of or explaining the present invention, but does not limit the scope of the present invention.

According to the present invention, it is possible to manufacture a long-life secondary battery capable of maintaining a high charge / discharge capacity for a long period of time despite the repetition of charge / discharge cycles. Therefore, it is possible to minimize inconvenience and resource waste of the consumer of the electronic product due to frequent replacement of the secondary battery.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 is a cross-sectional view of an electrode for a secondary battery according to an embodiment of the present invention,
Fig. 2 illustrates the surface roughness profile obtained in accordance with JIS B 0601 (2001)
FIGS. 3 and 4 are photographs showing the states of the cathodes after the charge / discharge tests of the secondary batteries manufactured using the electrolytic copper foils of Example 1 and Comparative Example 1, respectively.

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

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Therefore, the present invention encompasses all changes and modifications that come within the scope of the invention as defined in the appended claims and equivalents thereof.

The lithium ion secondary battery includes a cathode, an anode, an electrolyte that provides an environment in which lithium ions can move between the anode and the cathode, and electrons generated from one electrode, And a separator electrically isolating the anode and the cathode from each other to prevent the electrode from being wasted by moving to the other electrode.

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

1, an electrode 100 for a secondary battery according to an embodiment of the present invention includes an electrolytic copper foil 110 having a first surface S1 and a second surface S2 opposite to the first surface S1, A first active material layer 120a on the first surface S1 and a second active material layer 120b on the second surface S2. 1 shows an example in which active material layers 120a and 120b are formed on both the first and second surfaces S1 and S2 of the electrolytic copper foil 110. However, the present invention is not limited thereto, The secondary battery electrode 100 may include only one of the first and second active material layers 120a and 120b as an active material layer.

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

According to an embodiment of the present invention, the secondary battery electrode 100 is used as a cathode of a lithium secondary battery, and the electrolytic copper foil 110 functions as an anode collector, and the first and second active material layers 120a, 120b include a negative electrode active material.

1, the electrolytic copper foil 110 of the present invention includes a copper layer 111 including a matte surface MS and a shiny surface SS, a copper layer 111, A first protective layer 112a on the mat surface MS of the copper layer 111 and a second protective layer 112b on the shiny surface SS of the copper layer 111. [

The mat surface MS is a surface of the copper layer 111 facing the first surface S1 of the electrolytic copper foil 110. The shiny surface SS is formed on the second surface S2 of the electrolytic copper foil 110, Is the surface of the copper layer 111 facing the copper layer 111.

The copper layer 111 of the present invention may be formed on the rotating cathode drum through electroplating, which refers to the surface that has come into contact with the rotating cathode drum during the electroplating process, MS) refers to the opposite side of the shiny surface SS.

Although it is common that the shiny surface SS has a lower surface roughness R _z than the mat surface MS, the present invention is not limited to this, and the surface roughness R _z of the shiny surface SS is not limited to the mat surface May be equal to or higher than the surface roughness (R _z ) of the substrate (MS).

The first and second protective layers 112a and 112b may include chromium (Cr) for preventing corrosion of the copper layer 111 and improving heat resistance.

The electrolytic copper foil 110 of the present invention may have a yield strength of 21 to 58 kgf / mm ² at room temperature (25 占 15 占 폚). The yield strength is measured using a universal testing machine (UTM) with a sample width of 12.7 mm, a distance between grips of 50 mm, and a measurement speed of 50 mm / min.

If the yield strength of the electrolytic copper foil 110 is less than 21 kgf / mm ² , the electrolytic copper foil 110 may be wrinkled and / or folded due to the force applied during the manufacturing process of the electrode 100 and / or the manufacturing process of the secondary battery . On the other hand, if the yield strength of the electrolytic copper foil 110 exceeds 58 kgf / mm ² , the workability of the secondary battery manufacturing process is lowered.

The electrolytic copper foil 110 of the present invention may have an elongation of 3% or more at room temperature (25 占 15 占 폚). If the elongation percentage of the electrolytic copper foil 110 is less than 3%, the electrolytic copper foil 110 is not stretched due to the force applied during the manufacturing process of the electrode 100 and / or the manufacturing process of the secondary battery, and the risk of tearing is increased.

The electrolytic copper foil 110 of the present invention may have a thickness of 4 to 30 占 퐉.

The first and second active material layers 120a and 120b may be formed of a material selected from the group consisting of carbon; A metal of Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe; An alloy comprising the metal; An oxide of the metal; And at least one active material selected from the group consisting of a composite of the metal and carbon may be included as a negative electrode active material.

In order to increase the charge / discharge capacity of the secondary battery, the first and second active material layers 120a and 120b may be formed of a mixture containing a predetermined amount of Si.

As the charging and discharging of the secondary battery is repeated, the active material layers 120a and 120b are alternately shrunk and expanded. This causes separation of the active material layers 120a and 120b and the electrolytic copper foil 110, Thereby lowering the charging / discharging efficiency. Therefore, in order for the secondary electrode to maintain a capacity retention rate and lifetime of a certain level or higher (i.e., to suppress the charge-discharge efficiency deterioration of the secondary battery), the electrolytic copper foil 110 has excellent coating properties with respect to the active material, The adhesive strength between the active layer 110 and the active material layers 120a and 120b must be high.

It is generally known that the adhesion strength between the electrolytic copper foil 110 and the active material layers 120a and 120b can be improved by controlling the surface roughness Rz of the electrolytic copper foil 110. [ The surface roughness (Rz) can be measured according to JIS B 0601 (2001) standard using a Mahrsurf M300 illuminometer manufactured by Mahr Co. [Measuring length: 4 mm (excluding cut off section)].

According to an embodiment of the present invention, the surface roughness Rz of each of the first and second surfaces S1 and S2 of the electrolytic copper foil 110 may be 2.5 占 퐉 or less. When the surface roughness Rz exceeds 0.25 mu m, the first and second surfaces S1 and S2 of the electrolytic copper foil 110 are excessively uneven and coating uniformity of the negative electrode active material is lowered. As a result, the electrolytic copper foil 110 And the first and second active material layers 120a and 120b are remarkably lowered.

Actually, however, the electrolytic copper foil 110 whose surface roughness Rz is appropriately adjusted (for example, adjusted to 2.5 占 퐉 or less) has an adhesion force between the electrolytic copper foil 110 and the active material layers 120a and 120b It does not necessarily satisfy. That is, the electrolytic copper foil 110 having a surface roughness Rz of 2.5 m or less can not always guarantee the secondary cell capacity retention rate (after 500 cycles / discharge) of 90% or more required in the industry.

In particular, when the active material layers 120a and 120b include Si in order to increase the capacity of the secondary battery, the relationship between the surface roughness R _z of the electrolytic copper foil 110 and the capacity retention rate of the secondary battery is further lowered.

According to the present invention, in securing the adhesion between the electrolytic copper foil 110 and the active material layers 120a and 120b, which is large enough to ensure a secondary battery capacity retention ratio of 90% or more, the peak roughness of the electrolytic copper foil 110 : Rp) was more important than surface roughness (Rz).

Hereinafter, the peak roughness Rp of the electrolytic copper foil 110 will be described in detail with reference to FIG.

In the present invention, " peak illuminance Rp " is measured according to the JIS B 0601 (2001) standard, and as shown in the surface roughness profile of FIG. 2, the mean peak of the highest peak in the surface roughness profile (sampling length: means the height from the mean line.

According to an embodiment of the present invention, each of the first and second surfaces S1 and S2 of the electrolytic copper foil 110 has a peak roughness Rp of 0.36 to 1.69 占 퐉 and a peak of the first surface S1 The difference between the roughness Rp and the peak roughness Rp of the second surface S2 is 0.6 mu m or less.

If the surface roughness Rp of the first and second faces S1 and S2 is less than 0.36 占 퐉, the active specific surface area of the electrolytic copper foil 110 that can contact the anode active material is too small, Sufficient adhesion between the second active material layers 120a and 120b can not be ensured. On the other hand, if the surface roughness Rp of the first and second surfaces S1 and S2 exceeds 1.69 mu m, the coating uniformity of the negative electrode active material is lowered. As a result, the electrolytic copper foil 110 and the first and second active materials The adhesion between the layers 120a and 120b is significantly lowered. Also, when charging and discharging the secondary battery, stress concentrates at a peak exceeding 1.69 占 퐉 to separate the negative electrode active material from the electrolytic copper foil 110. As a result, the capacity retention rate of the secondary battery decreases.

When the difference between the peak roughness Rp of the first surface S1 and the peak roughness Rp of the second surface S2 exceeds 0.6 탆, the first surface S1 and the first active material layer The difference between the adhesion of the first surface 120a and the adhesion between the second surface S2 and the second active material layer 120b becomes too large. This causes a decrease in the capacity retention rate of the secondary battery.

The adhesion amount of chromium (Cr) on the first and second surfaces S1 and S2 of the electrolytic copper foil 110 is also the same as that of the electrolytic copper foil 110 in securing the adhesive force between the electrolytic copper foil 110 and the active material layers 120a and 120b It was confirmed to be an important factor. The chromium (Cr) adherence can be measured through Atomic Absorption Spectrometry (AAS) analysis.

The electrolytic copper foil 110 is subjected to a heat treatment such that a hole is not formed in the electrolytic copper foil 110 after a sample of 10 cm x 10 cm is obtained by masticating and cutting the second surface S2 of the electrolytic copper foil 110 with a tape. Is dissolved in a nitric acid aqueous solution (mixed with commercial nitric acid and water at a ratio of 1: 1). The resulting solution is diluted with water to obtain 50 mL of a diluted solution and the diluted solution is analyzed with an atomic absorption spectrometer (AAS) at 25 캜 to measure the amount of chromium attached on the first surface S1 of the electrolytic copper foil 110 . Similarly, the amount of chromium deposited on the second surface S2 of the electrolytic copper foil 110 can be measured.

According to an embodiment of the present invention, the chromium (Cr) adhesion amount in each of the first and second surfaces is 0.5 to 5.5 mg / m ² . When the amount of Cr attached is less than 0.5 mg / m ^2, oxygen passes through the active material layers 120a and 120b to cause oxidation of the surface of the copper layer 111. As a result, Sufficient chemical bonding can not be provided. On the other hand, if the amount of Cr attached exceeds 5.5 mg / m ² , the hydrophobicity of the surface of the electrolytic copper foil 110 increases and the chemical affinity for the negative active material is lowered. As a result, the electrolytic copper foil 110 and the anode active material Lt; / RTI > can not be provided.

In addition, according to an embodiment of the present invention, in order to minimize the winding of the electrolytic copper foil 110 that may cause deterioration in workability, the chromium (Cr) deposition amount difference on the first and second surfaces S1 and S2 May be less than or equal to 2.5 mg / m ² .

Hereinafter, a method of manufacturing the electrolytic copper foil 110 according to an embodiment of the present invention will be described in detail.

The method of the present invention includes the steps of forming a copper layer 111 and forming a protective layer 112a, 112b on the copper layer 111.

First, an electrolytic solution containing 50 to 100 g / L of copper ion, 50 to 150 g / L of sulfuric acid, 3 to 12 ppm of bis (3-sulfopropyl) disulfide (SPS) and 50 ppm or less of chlorine is prepared .

Then, 40 spaced from each other in the electrolytic solution in to 60 ℃ positive electrode plate and the rotary cathode drum to 40 to 80 A / dm by passing a current density of ² by performing an electroplating anode the rotation of the copper layer 111, the drum .

According to the present invention, the electrolytic solution is maintained such that the total carbon (TC) in the electrolytic solution is maintained at 0.25 g / L or less during the electroplating. The total carbon content (TC) consists of Total Organic Carbon (TOC) and Total Inorganic Carbon (TIC), which can be analyzed through the TC measurement facility.

The high-purity copper wire is heat-treated at 600 to 900 DEG C for 30 to 60 minutes to burn the organic matter, to pick up the heat-treated copper wire, to maintain the total carbon content (TC) of the electrolytic solution at 0.25 g / L or less, An electrolytic solution having no or little impurities is prepared by injecting pickled copper wire into sulfuric acid.

In order to maintain the total carbon content (TC) of the electrolytic solution at 0.25 g / L or less, the total amount of carbon (TC) may be lowered by decomposing organic substances in the electrolyte through ozone treatment. Further, by injecting hydrogen peroxide and air into the electrolytic solution during the electroplating, cleanliness of the electrolytic solution can be improved.

According to the present invention, the total concentration of scandium (Sc) and yttrium (Y) in the electrolytic solution is maintained at 350 mg / L or less during the electroplating.

The degree of polishing of the rotating cathode drum surface (surface on which copper is precipitated by electroplating) is also controlled by controlling the surface roughness Rz, peak roughness Rp, and chromium deposition amount of the second surface S2 of the electrolytic copper foil 110 . According to the present invention, the surface of the rotary cathode drum is polished with an abrasive brush having a grain size (Grit) of # 800 to # 1500.

The surface of the rotary cathode drum was polished with an abrasive brush having a grain size of # 800 to # 1500 so that the total amount of carbon (TC) of the electrolytic solution and the total concentration of scandium (Sc) and yttrium (Y) / L or less, and each administration to less than 350 mg / L, and by applying a current density of 40 to 80 a / dm ^2, the peak roughness (Rp) of the first and second surfaces (S1, S2) of the electrolytic copper foil 110 And peak roughness (Rp) in the range of the present invention (peak roughness (Rp): 0.36 to 1.69 mu m; Peak roughness (Rp) difference: 0.6 占 퐉 or less].

Continuous (or circulating) filtration to remove solid impurities from the electrolyte during the electroplating may be performed at a flow rate of 31 to 45 m ³ / hr. If the flow rate is less than 31 m ³ / hr, the flow velocity is lowered, the overvoltage is increased, and the copper layer 111 is formed non-uniformly. On the other hand, when the flow rate exceeds 45 m ³ / hr, filter damage is caused and foreign substances are introduced into the electrolyte, thereby increasing the total amount of carbon (TC) of the electrolyte.

Optionally, the electrolyte may further comprise at least one organic additive selected from the group consisting of hydroxyethyl cellulose (HEC), organic sulfides, organic nitrides, glycol based polymers, and thiourea based compounds .

The copper layer 111 thus prepared is dipped (for example, at room temperature for 2 to 20 seconds) in a rust preventive solution containing 0.5 to 1.5 g / L of Cr and dried to form a copper layer 111 on the copper layer 111 Thereby forming the first and second protective layers 112a and 112b, respectively.

The rust-preventive liquid may further include at least one of a silane compound and a nitrogen compound. For example, the rust-preventive liquid may comprise 0.5 to 1.5 g / L of Cr and 0.5 to 1.5 g / L of the silane compound.

By coating the anode active material on the electrolytic copper foil 110 of the present invention thus manufactured, the electrode (i.e., cathode) for a secondary battery of the present invention can be manufactured.

The negative electrode active material may include carbon; A metal of Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe; An alloy comprising the metal; An oxide of the metal; And a complex of the metal and carbon.

For example, 1 to 3 parts by weight of styrene butadiene rubber (SBR) and 1 to 3 parts by weight of carboxymethyl cellulose (CMC) are mixed with 100 parts by weight of carbon for an anode active material, and distilled water is used as a solvent to prepare a slurry. Next, the slurry is coated on the electrolytic copper foil 110 with a doctor blade at a thickness of 20 to 100 mu m and pressed at 110 to 130 DEG C under a pressure of 0.5 to 1.5 ton / cm < ² >.

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

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. It is to be understood, however, that the present invention is not limited to the following embodiments, but the scope of the present invention is not limited to these embodiments.

Examples 1 to 3 and Comparative Examples 1 to 5

A positive electrode plate and a rotating negative electrode drum which were arranged so as to be spaced apart from each other in the electrolyte solution were energized at a current density of 50 A / dm ² to form a copper layer. The electrolyte contained 75 g / L copper ion, 100 g / L sulfuric acid, 8 ppm bis (3-sulfopropyl) disulfide (SPS), and 20 ppm chlorine and was maintained at 55 ° C. During electroplating, continuous filtration was performed at a flow rate of 37 m ³ / hr to remove solid impurities from the electrolyte. (TC) of the electrolytic solution, the total concentration of scandium (Sc) and yttrium (Y) in the electrolyte solution, and the surface of the rotary cathode drum The particle size of the abrasive brush was as shown in Table 1 below. The copper layer formed through the electroplating was immersed in a rust preventive solution and then dried to complete an electrolytic copper foil.

ETU
(mg / L) TC
(g / L) Scandium (Sc) and yttrium (Y) (mg / L) Grinding Brush Size (#) Sc Y Total concentration Example 1 One 0.03 0.19 0.15 0.34 1000 Example 2 One 0.14 0.19 0.15 0.34 1500 Example 3 7 0.24 0.19 0.15 0.34 800 Comparative Example 1 0 0.03 0.21 0.15 0.36 1000 Comparative Example 2 0 0.27 0.19 0.15 0.34 800 Comparative Example 3 8 0.03 0.21 0.15 0.36 2000 Comparative Example 4 8 0.27 0.19 0.15 0.34 500 Comparative Example 5 8 0.14 0.19 0.15 0.34 500

The peak roughness Rp of the first surface (the surface of the electrolytic copper foil whose mat surface of the copper layer faces) and the second surface of the electrolytic copper foil of Examples 1-3 and Comparative Example 1-5 manufactured as described above, The yield strength of the electrolytic copper foil was obtained as follows. The capacity retention ratios of the secondary batteries including the negative electrode made from the electrolytic copper foils of Examples 1-3 and Comparative Examples 1-5 were obtained as follows. The measurement results are shown in Table 2 below.

* Peak roughness (Rp) (占 퐉)

The peak roughness (Rp) of arbitrary three points was measured for each of the first and second surfaces of the electrolytic copper foil, and the average value thereof was determined.

The peak illuminance (Rp) at each point was determined by measuring the height from the mean line of the highest peak in the surface roughness profile according to JIS B 0601 (2001). At this time, the illuminometer used was an SJ-310 illuminometer manufactured by Mitsutoyo Co., Ltd. The scan speed was 0.1 mm / sec, the measurement length was 4 mm, and the probe size was 5 μm.

* Yield strength at room temperature (25 ± 15 ° C) (kgf / mm ² )

The room temperature yield strength of the electrolytic copper foil was measured using a universal testing machine (UTM). The width of the sample was 12.7 mm, the distance between the grips was 50 mm, and the measurement speed was 50 mm / min.

* Capacity retention rate of secondary battery (%)

First, cathodes were prepared from the electrolytic copper foils of Example 1-3 and Comparative Example 1-5. Specifically, 2 parts by weight of SBR (styrene butadiene rubber) and 2 parts by weight of CMC (caroboxymethylcellulose) were mixed with 100 parts by weight of carbon commercially available as an anode active material. Then, a slurry was prepared by adding distilled water as a solvent to this mixture. The slurry was coated on the surface of an electrolytic copper foil (width: 10 cm) to a thickness of about 60 μm using a doctor blade, dried at 120 ° C., and then subjected to a roll pressing process (pressure: 1 ton / cm ² ) to prepare a negative electrode.

Lithium manganese oxide _{(Li 1. 1 Mn 1.} 85 Al 0. 05 O 4) and lithium manganese oxide (LiMnO _2-o) in the orthorhombic crystal structure was prepared the positive electrode active material were mixed at a weight ratio of 90:10. The above cathode active material, carbon black, and polyvinylidene fluoride (PVDF) were mixed with NMP as an organic solvent at a weight ratio of 85: 10: 5 to prepare a slurry. The slurry was coated on both sides of an aluminum foil having a thickness of 20 mu m and dried to prepare a positive electrode.

Further, 1 M of LiPF ₆ dissolved as a solute in a non-aqueous organic solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a weight ratio of 1: 2 was used as a basic electrolyte, and 99.5% by weight of this basic electrolyte, And 0.5 wt% of succinic anhydride were mixed to prepare an electrolyte solution for a secondary battery.

A secondary battery was prepared from the thus prepared negative electrode, positive electrode, and electrolyte.

Subsequently, the capacity per g of the positive electrode was measured with the charging operating voltage of 4.3 V and the discharging operating voltage of 3.4 V, and the charging / discharging performance was 500 times at a charging / discharging rate of 0.2 C at 50 캜 And the capacity retention rate of the secondary battery was calculated according to the following equation (1). The capacity retention rate of a secondary battery required in the industry is 90% or more.

[Formula 1]

Capacity retention ratio (%) = (discharge capacity of 500 turns / discharge capacity of one turn) x 100

Five samples were taken for each electrolytic copper foil and five secondary cells were prepared by the above-mentioned five samples. The capacity retention ratios of the five secondary batteries were measured by the above-mentioned methods, Quot; secondary cell capacity retention ratio " corresponding to the electrolytic copper foil was obtained by arithmetic averaging.

Rp (占 퐉) Yield strength (kgf / mm ² ) Capacity retention rate (%) The first side Second side Difference Example 1 0.37 0.92 0.55 22.8 95 Example 2 1.04 0.67 0.37 23.2 97 Example 3 1.67 1.55 0.12 57.6 93 Comparative Example 1 0.33 0.89 0.56 20.5 78 Comparative Example 2 1.71 1.54 0.17 20.5 75 Comparative Example 3 0.32 0.35 0.03 59.2 73 Comparative Example 4 1.72 1.75 0.03 59 78 Comparative Example 5 1.05 1.71 0.66 58.5 63

From Table 2, it can be seen that when either of the first and second surfaces of the electrolytic copper foil has a peak roughness Rp of less than 0.36 占 퐉 (Comparative Examples 1 and 3), even if any one of the first and second surfaces of the electrolytic copper foil has a peak roughness Rp of 1.69 (Comparative Examples 2 and 4) and a peak roughness (Rp) difference between the first and second surfaces of the electrolytic copper foil exceeded 0.6 mu m (Comparative Example 5) It can be seen that the capacity retention rate of the battery is significantly lower than the value (90%) required in the industry.

FIGS. 3 and 4 are photographs showing states of cathodes after charge / discharge tests are performed on the secondary batteries manufactured using the electrolytic copper foils of Example 1 and Comparative Example 1. FIG.

As shown in FIG. 3, the negative electrode manufactured by the electrolytic copper foil of Example 1 firmly adhered to the copper layer and the active material layer even after the 500 times charge / discharge test. On the other hand, as shown in FIG. 4, it can be seen that a significant portion of the active material layer was separated from the copper layer after the 500 times charge / discharge test of the negative electrode manufactured by the electrolytic copper foil of Comparative Example 1. FIG.

100: secondary battery electrode 110: electrolytic copper foil
111: copper layer 112a: first protective layer
112b: second protective layer 120a: first active material layer
120b: second active material layer

Claims (16)

An electrolytic copper foil having a first surface and a second surface opposite to the first surface,
A copper layer comprising a matte surface facing the first surface and a shiny surface facing the second surface;
A first protective layer on the mat surface; And
And a second protective layer on the shiny surface,
Each of the first and second surfaces has a peak roughness (Rp) of 0.36 to 1.69 占 퐉,
Wherein the difference between the peak roughness of the first surface and the peak roughness of the second surface is 0.6 占 퐉 or less.
An electric boat. The method according to claim 1,
Wherein each of the first and second protective layers comprises chromium (Cr)
Wherein the amount of chromium (Cr) deposited on each of the first and second surfaces is 0.5 to 5.5 mg / m ² .
An electric boat. 3. The method of claim 2,
Wherein a difference between a chromium (Cr) deposition amount on the first surface and a chromium (Cr) deposition amount on the second surface is 2.5 mg / m ² or less.
An electric boat. The method according to claim 1,
Wherein a surface roughness (Rz) of each of the first and second surfaces is 2.5 占 퐉 or less.
An electric boat. The method according to claim 1,
And has a yield strength of 21 to 58 kgf / mm < ² > at room temperature of 25 ± 15 ° C.
An electric boat. The method according to claim 1,
Characterized in that it has a thickness of 4 to 30 mu m.
An electric boat. An electrolytic copper foil having a first surface and a second surface opposite to the first surface; And
And a first active material layer on the first surface,
The electrolytic copper foil,
A copper layer including a mat surface facing the first surface and a shiny surface facing the second surface;
A first protective layer on the mat surface; And
And a second protective layer on the shiny surface,
Each of the first and second surfaces has a peak roughness (Rp) of 0.36 to 1.69 占 퐉,
Wherein the difference between the peak roughness of the first surface and the peak roughness of the second surface is 0.6 占 퐉 or less.
Electrode for secondary battery. 8. The method of claim 7,
Wherein each of the first and second protective layers comprises chromium (Cr)
The amount of chromium (Cr) deposited on each of the first and second faces is 0.5 to 5.5 mg / m ² ,
Wherein a difference between a chromium (Cr) deposition amount on the first surface and a chromium (Cr) deposition amount on the second surface is 2.5 mg / m ² or less.
Electrode for secondary battery. 8. The method of claim 7,
Characterized in that the electrolytic copper foil has a yield strength of 21 to 58 kgf / mm < ² > at room temperature of 25 ± 15 ° C.
Electrode for secondary battery. 8. The method of claim 7,
Further comprising a second active material layer on the second surface,
The first and second active material layers may be, independently from each other, carbon; A metal of Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe; An alloy comprising the metal; An oxide of the metal; And at least one active material selected from the group consisting of a complex of said metal and carbon.
Electrode for secondary battery. A cathode;
An anode comprising the electrode for a secondary battery according to any one of claims 7 to 10;
An electrolyte for providing an environment in which lithium ions can move between the anode and the cathode; And
And a separator for electrically insulating the anode and the cathode.
Secondary battery. Forming a copper layer; And
And forming a protective layer on the copper layer,
The copper layer forming step may include:
Preparing an electrolytic solution containing 50 to 100 g / L of copper ion, 50 to 150 g / L of sulfuric acid, 3 to 12 ppm of bis (3-sulfopropyl) disulfide (SPS), and 50 ppm or less of chlorine; And
And performing electroplating by energizing a positive electrode plate and a rotating negative electrode drum disposed apart from each other in the electrolyte at a current density of 40 to 80 A / dm ² ,
During the electroplating, the total carbon (TC) in the electrolyte is maintained at 0.25 g / L or less and the total concentration of scandium (Sc) and yttrium (Y) in the electrolyte is 350 mg / L or less Lt; / RTI >
Characterized in that the surface of the rotary cathode drum is polished with an abrasive brush having a grain size of # 800 to # 1500.
Method of manufacturing electrolytic copper foil. 13. The method of claim 12,
In the step of preparing an acidic electrolyte,
Heat treating the copper wire at 600 to 900 占 폚 for 30 to 60 minutes;
Pickling the heat-treated copper wire; And
And introducing the pickled copper wire into sulfuric acid.
Method of manufacturing electrolytic copper foil. 13. The method of claim 12,
The copper layer forming step may include:
Further comprising the step of injecting hydrogen peroxide and air into the electrolyte while the electroplating is performed.
Method of manufacturing electrolytic copper foil. 13. The method of claim 12,
Wherein the electrolyte solution further comprises at least one organic additive selected from the group consisting of hydroxyethyl cellulose (HEC), organic sulfide, organic nitride, glycol based polymer, and thiourea based compound doing,
Method of manufacturing electrolytic copper foil. 13. The method of claim 12,
Wherein the forming of the protective layer comprises immersing the copper layer in an anticorrosive solution containing 0.5 to 1.5 g / L of Cr.
Method of manufacturing electrolytic copper foil.

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