KR20190025418A - Copper foil capable of manufacturing high capacity secondary battery, electrode comprisng the same, secondary battery comprising the same and method for manufacturing the same - Google Patents

Abstract

One embodiment of the present invention provides a copper foil, comprising: a copper layer having a matte surface and a shiny surface; and a rust preventive film disposed on the copper layer. The copper foil has a room temperature (25±15°C) tensile strength of 40-60 kgf/mm^2 and a high temperature tensile strength of 36-55 kgf/mm^2 after heat treatment at 190°C for 1 hour. The copper layer has crystalline particles, wherein the crystalline particles have an average particle size of 0.7-1.5 μm after the heat treatment at room temperature and 190°C for 1 hour.

Description

TECHNICAL FIELD The present invention relates to a copper foil capable of producing a high-capacity secondary battery, an electrode including the same, a secondary battery including the same, and a method of manufacturing the same. BACKGROUND ART [0002] MANUFACTURING THE SAME}

The present invention relates to a copper foil that enables the production of a high capacity secondary battery, an electrode including the same, a secondary battery including the electrode, and a method of manufacturing the same.

A secondary cell is a type of energy conversion device that converts electrical energy into chemical energy, stores it, and converts the chemical energy into electrical energy when electricity is needed. The secondary battery is also referred to as a rechargeable battery in that it is rechargeable.

Among these secondary batteries, lithium secondary batteries have high operating voltage, high energy density and excellent lifetime characteristics. The secondary battery includes an anode current collector made of a copper foil, and the electrolytic copper foil among the copper foils is widely used as a cathode current collector of a secondary battery.

The electrolytic copper foil used as the negative electrode collector usually has a tensile strength of about 30 to 40 kgf / mm ² . Recently, a metal or composite active material having a high capacity characteristic has been spotlighted for the production of a high capacity lithium secondary battery, and the metal or composite active material has a significant volume expansion during charging and discharging. Therefore, the copper foil is not torn even when the active material expands in volume, and the active material is not removed from the copper foil, as long as the copper foil can cope with the volume expansion of the active material. In order to cope with the volume expansion of the active material, the copper foil must have a high strength property and the tensile strength of the copper foil should be maintained even after the high temperature process such as coating and drying of the active material.

On the other hand, for the production of a high strength copper foil having a tensile strength of 40 kgf / mm ² or more, electroplating is carried out using, for example, a sulfuric acid-based electrolyte to which a multi-component additive or a thiourea-based organic additive is added There is a way.

However, when the tensile strength of the copper foil increases, the stress in the copper foil increases and the frequency of occurrence of curl in the copper foil increases. When a curl occurs in the copper foil, a process of manufacturing a copper foil by the roll-to-roll (RTR) process or a process of manufacturing an electrode for a secondary battery using the copper foil causes wrinkles in the copper foil or tearing of the copper foil May occur.

In order to increase the capacity of the secondary battery, a very thin ultra-thin copper foil has been used in the manufacture of electrodes for secondary batteries. For example, an ultra-thin copper foil having a thickness of 10 mu m or less is used. However, such a thin copper foil has a low handling property, and due to its low handling property, it may be impossible to manufacture an electrode for a secondary battery using a copper foil.

Therefore, it is necessary to develop a copper foil capable of maintaining a high tensile strength even in a high-temperature process in order to improve handling and operability in the secondary battery manufacturing process and use of a metal-based active material.

The present invention relates to a copper foil capable of satisfying the above requirements, an electrode including the same, a secondary battery comprising the same, and a method of manufacturing the copper foil.

One embodiment of the present invention is to provide a copper foil having a high tensile strength even after heat treatment at a high temperature.

Another embodiment of the present invention controls the crystal structure of the copper foil so that the copper foil has a high tensile strength even after heat treatment at a high temperature.

Another embodiment of the present invention is to provide a copper foil having crystalline particles arranged densely by properly selecting an organic additive and controlling its content.

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

Another embodiment of the present invention relates to a method for manufacturing a copper foil, which comprises: appropriately selecting an organic additive contained in an electrolytic solution used in the production of a copper foil and adjusting the content thereof to control the crystal structure of the copper foil; And to provide a manufacturing method thereof.

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.

One embodiment of the present invention provides a copper foil having excellent tensile strength even after heat treatment by controlling the crystallinity of the copper foil.

To this end, one embodiment of the present invention provides a copper layer having a matte surface and a shiny surface; And a rust-preventive layer disposed on the copper layer, and including, 40 to room temperature (25 ± 15 ℃) tensile strength of 60kgf / mm ^2; And a high temperature tensile strength of 36 to 55 kgf / mm ² after heat treatment at 190 ° C for 1 hour. The copper layer has crystalline particles, and after heat treatment at room temperature and 190 ° C for 1 hour, the crystalline particles Has an average particle size of 0.7 to 1.5 [mu] m.

The copper foil has a maximum curl height of 15 mm or less.

The copper foil has a first surface in the matte surface direction and a second surface in the shiny surface direction, and the first surface and the second surface each have a surface roughness (Rz JIS) of 0.5 to 2.0 mu m.

The copper foil has a thickness of 4 to 35 mu m.

The rustproofing film includes at least one of chromium, a silane compound and a nitrogen compound.

Another embodiment of the present invention provides an electrode for a secondary battery comprising the copper foil and the active material layer disposed on at least one side of the copper foil.

 Another embodiment of the present invention is a fuel cell comprising: a cathode; An anode disposed opposite to the anode; An electrolyte disposed between the anode and the cathode to provide an environment in which lithium ions can move; And a separator for electrically insulating the positive electrode and the negative electrode, wherein the negative electrode comprises the copper foil and the active material layer disposed on the copper foil.

According to another embodiment of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a copper layer by passing a positive electrode plate and a rotating cathode drum spaced apart from each other in an electrolytic solution containing copper ions at a current density of 30 to 80 ASD (A / dm ² ); Wherein the electrolytic solution contains 60 to 120 g / L of copper ions; 80 to 150 g / L sulfuric acid; Less than 50 ppm chlorine (Cl); And an organic additive, wherein the organic additive is at least one selected from a brightener (component A) and a retarder (component B); And a leveling agent (component C), wherein the brightener (component A) comprises a sulfonic acid or a metal salt thereof, the retarder (component B) comprises a nonionic water soluble polymer, and the leveling agent (component C) Comprises at least one of nitrogen (N) and sulfur (S).

In the step of forming the copper layer, the temperature of the electrolyte is maintained in the range of 40 to 60 占 폚.

The brightener has a concentration of 5 to 100 ppm.

The polish may be selected from the group consisting of bis- (3-sulfopropyl) -disulfide disodium salt (SPS), 3-mercapto-1-propanesulfonic acid, 3- -Dimethylthiocarbamoyl) -thiopropanesulfonate sodium salt, 3 - [(amino-iminomethyl) thio] -1-propanesulfonate sodium salt, o-ethyldithiocarbonate-S- ) -Ester sodium salt, 3- (benzothiazolyl-2-mercapto) -propyl-sulfonic acid sodium salt and ethylenedithiodipropylsulfonic acid sodium salt.

The retarder has a concentration of 5 to 50 ppm.

The decelerator may be selected from the group consisting of polyethylene glycol (PEG), polypropylene glycol, polyethylene polypropylene copolymer, polyglycerin, polyethylene glycol dimethyl ether, hydroxyethylene cellulose, polyvinyl alcohol, stearic acid polyglycol ether and stearyl alcohol polyglycol And at least one non-ionic water-soluble polymer selected from the group consisting of water and ether.

The nonionic water soluble polymer has a number average molecular weight of 500 to 25,000.

The leveling agent has a concentration of 1 to 50 ppm.

The leveling agent may be at least one selected from the group consisting of diallyldimethylammonium chloride (DDAC), thiourea, N, N'-dimethylthiourea, N, N'-diethylthiourea, tetramethylthiourea, Mercapto benzothiazole, 5-mercapto-1-methyl tetrazole (5-MM) and polyethyleneimine (5-mercapto- PEI). ≪ / RTI >

The organic additive may include two or more different leveling agents (component C).

The organic additive may include at least one leveling agent (C component) including nitrogen (N) and at least one leveling agent (C component) including sulfur (S).

The method of manufacturing the copper foil further includes forming a rustproof film on the copper layer.

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 one embodiment of the present invention, the crystallinity and the tensile strength of the copper foil are controlled to reduce the curl of the copper foil. This prevents wrinkles or tearing of the copper foil in the manufacturing process of the copper foil or the manufacturing process of the secondary battery electrode or the secondary battery using such a copper foil. In addition, the secondary battery manufactured using such a copper foil has an excellent capacity retention ratio, and the capacity of the secondary battery can be increased.

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 schematic cross-sectional view of a copper foil according to an embodiment of the present invention.
2 is a schematic cross-sectional view of a copper foil according to another embodiment of the present invention.
3 is a schematic cross-sectional view of an electrode for a secondary battery according to another embodiment of the present invention.
4 is a schematic cross-sectional view of an electrode for a secondary battery according to another embodiment of the present invention.
5 is a schematic cross-sectional view of a secondary battery according to another embodiment of the present invention.
6 is a schematic view of a process for manufacturing the copper foil shown in Fig.
7 is a schematic view for explaining the measurement of the curl height of the copper foil.
8A and 8B show cross sections of the copper foil according to Production Example 3 before and after the heat treatment, respectively.
9A and 9B show cross sections of the copper foil according to Comparative Example 3 before and after the heat treatment, 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. Accordingly, the invention includes all modifications and variations within the scope of the invention as defined in the claims and their equivalents.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings are illustrative to describe embodiments of the present invention, and thus the present invention is not limited by what is shown in the drawings. Like elements throughout the specification may be referred to by like reference numerals.

Where the terms "comprises", "having", "comprising", and the like are used herein, other portions may be added unless the expression "only" is used. Where an element is referred to in the singular, it includes the plural unless specifically stated otherwise. Further, in interpreting the constituent elements, even if there is no separate description, it is interpreted to include an error range.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is used, one or more other portions may be located between the two portions.

In the case of a description of a temporal relationship, for example, if the temporal relationship is described by 'after', 'after', 'after', 'before', etc., May not be continuous unless the expression " expression " is used.

In order to describe various components, expressions such as 'first', 'second', etc. are used, but these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

It should be understood that the term " at least one " includes all possible combinations from one or more related items.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

1 is a schematic cross-sectional view of a copper foil 101 according to an embodiment of the present invention.

The copper foil 101 according to an embodiment of the present invention includes a copper layer 110. The copper layer 110 has a matte surface MS and a shiny surface SS opposite the matte surface MS.

The copper layer 110 may be formed on the rotating cathode drum, for example, by electroplating (see FIG. 6). In this case, the shiny surface SS refers to the surface that has contacted the rotating cathode drum in the electroplating process, and the mat surface MS refers to the opposite surface to the shiny surface SS.

Generally, the shiny surface SS has a lower surface roughness than the matte surface MS. However, the embodiment of the present invention is not limited to this, and the surface roughness of the shiny surface SS may be equal to or higher than the surface roughness of the mat surface MS. For example, depending on the degree of polishing of the rotary cathode drum 12 (see FIG. 6) used for manufacturing the copper layer 110, the surface roughness of the shiny surface SS is lower than the surface roughness of the matte surface MS It may or may not be high. The surface of the rotating cathode drum 12 can be polished by an abrasive brush having a grain size of # 800 to # 3000.

Referring to FIG. 1, the copper foil 101 includes a rust preventive film 211 disposed on a copper layer 110. The anticorrosive film 211 may be omitted.

The rust preventive film 211 may be disposed on at least one of the matte surface MS and the shiny surface SS of the copper layer 110. [ Referring to Fig. 1, a rust preventive film 211 is disposed on the mat surface MS. However, the embodiment of the present invention is not limited to this, and the rust preventive film 211 may be disposed only on the shiny side SS or on both the mat side MS and the shiny side SS.

The anticorrosive film 211 protects the copper layer 110 to prevent the copper layer 110 from being oxidized or deteriorated. Therefore, the anticorrosive film 211 is also referred to as a protective layer.

According to one embodiment of the present invention, the anticorrosive film 211 may include at least one of chromium (Cr), a silane compound, and a nitrogen compound. For example, the anticorrosive film 211 can be made of a rustproofing solution containing chromium (Cr), that is, a rustproofing solution containing a chromate compound.

According to one embodiment of the present invention, the copper foil 101 has a first surface S1 in the direction of the mat surface MS and a second surface S1 in the direction of the shiny surface SS, (S2). 1, the first surface S1 of the copper foil 101 is the surface of the anticorrosive film 211, and the second surface S2 is the shiny surface SS. When the anticorrosive film 211 is omitted, the mat surface MS of the copper layer 110 becomes the first surface S1 of the copper foil 101. [

According to one embodiment of the present invention, the first surface S1 and the second surface S2 of the copper foil 100 each have a surface roughness (Rz JIS) of 0.5 to 2.0 占 퐉.

The surface roughness (Rz JIS) according to an embodiment of the present invention is also referred to as a ten-point average roughness and can be measured by a surface roughness meter (M300, Mahr) according to JIS B 0601-2001.

When the surface roughness (Rz JIS) of the first surface S1 and the second surface S2 of the copper foil 101 is less than 0.5 mu m each, when the copper foil 101 is used as the current collector of the electrode for the secondary battery, 101 and the active material is low, so that the peeling strength is lowered. As a result, the active material can be removed from the copper foil 101 during charging / discharging of the secondary battery. On the other hand, when the surface roughness Rz JIS of the first surface S1 and the second surface S2 exceeds 2.0 占 퐉, when the copper foil 101 is used as a current collector of the electrode for a secondary battery, ), The current may locally concentrate at the time of charge / discharge of the secondary battery, so that the charge / discharge cycle characteristic may be deteriorated, and the capacity retention rate of the secondary battery may be lowered.

According to an embodiment of the present invention, the difference in surface roughness Rz JIS between the first surface S1 and the second surface S2 of the copper foil 101 can be adjusted to 0.5 占 퐉 or less.

When the difference in surface roughness Rz JIS between the first surface S1 of the copper foil 101 and the second surface S2 exceeds 0.5 占 퐉, when the copper foil 101 is used as the current collector of the electrode for the secondary battery, The active material may not be uniformly coated on both surfaces of the first surface S1 and the second surface S2 due to the difference in surface roughness Rz JIS between the first surface S1 and the second surface S2. Accordingly, when the secondary battery is charged and discharged, the electrical and physical characteristics of the two surfaces (S1, S2) may be different from each other, and the service life of the secondary battery may be rapidly deteriorated.

On the other hand, when the difference in surface roughness Rz JIS between the first surface S1 of the copper foil 101 and the second surface S2 is 0.5 탆 or less, when the copper foil 101 is used as a current collector of a secondary battery electrode, The coating of the active material is similar on both sides of the secondary battery 101, so that the stability and the capacity retention rate of the secondary battery upon charging and discharging are improved, and the lifetime of the secondary battery can be increased accordingly.

According to one embodiment of the invention, the copper foil 101 has a room temperature (25 ± 15 ℃) a tensile strength of 40 to 60 kgf / mm ^2. The tensile strength at room temperature (25 占 15 占 폚) is referred to as room temperature tensile strength.

The tensile strength can be measured by a universal testing machine (UTM) in accordance with the provisions of the IPC-TM-650 Test Method Manual. According to one embodiment of the present invention, the tensile strength is measured by an universal testing machine of Instron. The width of the sample for tensile strength measurement is 12.7 mm, the distance between the grips is 50 mm, and the measurement speed is 50 mm / min.

When the tensile strength of the copper foil 101 is less than 40 kgf / mm ² at room temperature, when the copper foil 101 is used as the current collector of the electrode for the secondary battery, the copper foil 101 may be broken due to the volume expansion of the active material have. For example, a metal-based active material containing tin (Sn) or silicon (Si) has a very large volume expansion upon charging and discharging, and the large-volume expansion of the metal-based active material can break the copper foil attached to the active material. To prevent this, the copper foil 101 according to an embodiment of the present invention has a tensile strength of 40 kgf / mm ² or more.

When the tensile strength of the copper foil 101 is less than 40 kgf / mm ² at room temperature, the copper foil 101 curls in the roll-to-roll process for producing the copper foil 101 or the secondary battery, Or wrinkles may occur.

On the other hand, when the tensile strength of the copper foil 101 exceeds 60 kgf / mm < ² > at room temperature, the brittleness of the copper foil 101 increases during the manufacturing process of the copper foil 101 or the manufacturing process of the secondary battery using the copper foil 101 Can be broken.

Further, according to an embodiment of the present invention, the copper foil 101 has a high temperature tensile strength of 36 to 55 kgf / mm ² after heat treatment at 190 ° C for 1 hour. Here, the high-temperature tensile elongation refers to a tensile strength measured after heat treatment of the copper foil 101 at 190 占 폚 for 1 hour. The tensile strength measured after the heat treatment at a temperature of 190 ± 5 ° C for 1 hour ± 5 minutes may be referred to as a high temperature tensile strength.

If at 190 ℃ high-temperature tensile strength after heat treatment 1 hours 36kgf / mm ² is less than, it is the softening of the copper foil 101 is generated in the harsh processing conditions of high temperature, and the like can be wrinkling.

On the other hand, if the high temperature tensile strength after heat treatment exceeds 55 kgf / mm ² , the brittleness of the copper foil 101 may increase under severe conditions such as coating with an active material or high temperature drying, and breakage or the like may occur in the copper foil 101.

According to one embodiment of the present invention, the copper layer 110 of the copper foil 101 has crystallinity and may include crystalline grains (see Figs. 8A, 8B, 9A, and 9B). The physical and mechanical characteristics of the copper foil 101 including the copper layer 110 may vary depending on the crystallinity of the copper layer 110. [

In one embodiment of the present invention, the crystalline particles have the appearance of a specific polyhedron, or X-ray diffraction phenomenon is confirmed by a crystal lattice consisting of a periodic array of atoms even if it does not have the appearance of a specific polyhedron It contains all the particles that can be.

The crystalline particles contained in the copper layer 110 have an average particle size of 0.7 to 1.5 占 퐉 before and after the heat treatment at 190 占 폚 for 1 hour. More specifically, over the cross-section of the copper layer 110 cut in the thickness direction of the copper layer 110, the average grain size of the crystalline particles is 0.7 to 1.0 μm in both the heat treatment and the heat treatment for 1 hour at 190 ° C. Lt; / RTI >

The average particle size of the crystalline particles contained in the copper layer 110 can be measured by an Electron Back Scattered Diffraction (EBSD) method. More specifically, after analyzing the first surface S1 and the second surface S2 of the copper foil 101 by the EBSD method before or after the heat treatment, the average particle size of the crystalline particles is calculated using the analysis result . For example, a device equipped with an Electron Backscatter Diffraction (EBSD) detector (eg EDAX EBSD camera) on a Field Emission-Scanning Electron Microscope (FE-SEM) The average particle size of the crystalline particles contained in the copper layer 110 can be measured by observing the cross section of the copper foil 101 under the measurement conditions of a voltage of 15 kV, a current of 50 mA and a magnification of 2000 times.

At 190 ℃ 1 sigan heat treatment before and after, when the average particle size of the crystalline particles comprising the copper layer 110 is 0.7 to 1.5㎛, the copper foil 101 of 40 to room temperature for ^{60kgf / mm 2 (25 ± 15} ℃ ) Tensile strength and high temperature tensile strength of 36 to 55 kgf / mm < ² >. On the other hand, when the average particle size of the crystalline particles comprising the copper layer 110 is outside the range of 0.7 to 1.5㎛, temperature of the copper foil (101) (25 ± 15 ℃ ) a tensile strength of 40 to a range of 60kgf / mm ² Or the high temperature tensile strength may be out of the range of 36 to 55 kgf / mm < ² >.

More specifically, if the average particle size of the crystalline particles contained in the copper layer 110 is small and small, the copper foil 101 can have high strength. In this regard, the nitrogen (N) or sulfur (S) component derived from the organic additive added to the electrolytic solution is vacated in the grain structure of the copper layer 110 so that even after the heat treatment, And exhibits a pin effect that prevents the particle size from becoming large. When the average particle size of the crystalline particles contained in the copper layer 110 at room temperature is 0.7 μm or less, the crystalline particles are too fine and the strength of the copper foil 101 is excessively high, resulting in increased brittleness of the copper foil 101, The possibility of tearing is increased in the stripping process using a rotating cathode drum. On the other hand, when the average particle size of the crystalline particles contained in the copper layer 110 exceeds 1.5 탆, it becomes difficult to realize the high strength of the copper foil 101.

According to an embodiment of the present invention, the size of the crystalline particles included in the copper layer 110 can be maintained without significantly increasing even after the heat treatment. Accordingly, the copper foil 101 can have an excellent tensile strength even after the heat treatment.

According to an embodiment of the present invention, the maximum curl height of the copper foil 101 is 15 mm or less.

In order to measure the maximum curl height of the copper foil 101, the copper foil 101 is cut into 60 mm X 60 mm, and the copper foil 101 is placed on the support so that the first surface S1 faces upward , A glass plate is disposed on the copper foil 101. [ At this time, the length of the cut copper foil was set so that only half the length of the copper foil was overlapped with the glass plate so that only half of the copper foil 101 was positioned between the support and the glass plate. Then, the height of the copper foil exposed to the outside of the glass plate was measured, Is defined as the maximum curl height of the base 101 (see FIG. 7).

When the maximum curl height of the copper foil 101 exceeds 15 mm, the copper foil 101 may be teared or wrinkled during the winding of the copper foil 101 or during the manufacturing process of the secondary battery using the copper foil 101 wrinkle may occur. Further, when a curl is generated in the copper foil 101, it may be difficult to separate the copper foil 101 from the winder WR after the production of the copper foil 101.

According to one embodiment of the present invention, the copper foil 101 may have a thickness of 4 mu m to 35 mu m. When the copper foil 101 is used as the current collector of the electrode for the secondary battery, the thinner the copper foil 101, the more current collectors can be accommodated in the same space, which is advantageous for the high capacity of the secondary battery. However, when the thickness of the copper foil 101 is less than 4 占 퐉, workability in the process of manufacturing the secondary battery electrode or the secondary battery using the copper foil 101 is lowered.

On the other hand, when the thickness of the copper foil 101 is more than 35 μm, the thickness of the electrode for the secondary battery using the copper foil 101 becomes large, and it may be difficult to realize a high capacity of the secondary battery due to such a large thickness.

According to one embodiment of the present invention, the copper foil 100 may have an elongation of 2 to 20% after heat treatment at room temperature of 25 占 15 占 폚 or 1 hour at 190 占 폚. The elongation can be measured by a universal testing machine (UTM) according to the method specified in the IPC-TM-650 Test Method Manual. According to an embodiment of the present invention, an equipment of Instron can be used. At this time, the width of the sample for elongation measurement was 12.7 mm, the distance between the grips was 50 mm, and the measurement speed was 50 mm / min.

If the elongation percentage of the copper foil 100 is less than 2%, there is a risk that the copper foil 101 will not sufficiently stretch and tear in response to a large volume expansion of the active material used in the high capacity secondary battery. On the other hand, if the elongation is excessively large exceeding 20%, the copper foil 101 easily stretches in the electrode manufacturing process for the secondary battery, and the electrode may be deformed.

2 is a schematic cross-sectional view of a copper foil 102 according to another embodiment of the present invention. Hereinafter, in order to avoid redundancy, a description of the components already described is omitted.

2, a copper foil 102 according to another embodiment of the present invention includes two copper foils 110 and two copper foils 110 disposed on a mat surface MS and a shiny surface SS, respectively, Films 211 and 212, respectively. Compared to the copper foil 101 shown in Fig. 1, the copper foil 102 shown in Fig. 2 further includes the anticorrosive film 212 disposed on the shiny side SS of the copper layer 110. Fig.

The rust preventive film 211 disposed on the mat surface MS of the copper layer 110 among the two rustproof films 211 and 212 is referred to as a first protective layer and is disposed on the shiny surface SS The rust-preventive film 212 is also referred to as a second protective layer.

The copper foil 102 shown in Fig. 2 has a first surface S1 which is a surface in the direction of the mat surface MS and a second surface which is a surface in the direction of the shiney surface SS, (S2). Here, the first surface S1 of the copper foil 102 is the surface of the anticorrosive film 211 disposed on the matte surface MS and the second surface S2 is the antireflection film 212 disposed on the shiny surface SS ).

According to another embodiment of the present invention, the two rustproofing films 211 and 212 may each include at least one of chromium (Cr), a silane compound and a nitrogen compound.

Copper foil 102 according to another embodiment of the present invention has a high temperature tensile strength of 40 to 60kgf / mm ² at room temperature (25 ± 15 ℃) after 1 hour heat treatment at a tensile strength and 190 ℃ 36 to 55kgf / mm ² . The copper layer 110 of the copper foil 102 has crystalline particles and the crystalline particles of the copper layer 110 have a mean particle size of 0.7 to 1.5 占 퐉 before and after the heat treatment at 190 占 폚 for 1 hour Size.

The copper foil 102 has a maximum curl height of 15 mm or less and the first surface S1 and the second surface S2 of the copper foil 102 have a surface roughness Rz JIS of 0.5 to 2.0 占 퐉, . Further, the copper foil 102 has a thickness of 4 to 35 mu m.

3 is a schematic cross-sectional view of an electrode 103 for a secondary battery according to another embodiment of the present invention. The secondary battery electrode 103 shown in Fig. 3 can be applied to the secondary battery 105 shown in Fig. 5, for example.

3, an electrode 103 for a secondary battery according to another embodiment of the present invention includes a copper foil 101 and an active material layer 310 disposed on the copper foil 101. As shown in FIG. Here, the copper foil 101 includes a copper foil 110 and a rust preventive film 211 disposed on the copper foil 110, and is used as a current collector.

Specifically, the copper foil 101 has a first surface S1 and a second surface S2, and the active material layer 310 is formed on at least one of the first surface S1 and the second surface S2 of the copper foil 101 Lt; / RTI > The active material layer 310 may be disposed on the anticorrosive film 211.

Fig. 3 shows an example in which the copper foil 101 of Fig. 1 is used as a current collector. However, another embodiment of the present invention is not limited thereto, and the copper foil 102 shown in Fig. 2 may be used as a collector of the electrode 103 for a secondary battery.

3 shows a structure in which the active material layer 310 is disposed only on the first surface S1 of the copper foil 101. However, the present invention is not limited thereto, The active material layer 310 may be disposed on both the first surface S1 and the second surface S2. In addition, the active material layer 310 may be disposed only on the second surface S2 of the copper foil 101. [

The active material layer 310 shown in FIG. 3 includes an electrode active material, and may particularly include a negative active material. That is, the secondary battery electrode 103 shown in FIG. 3 can be used as a negative electrode.

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

As the secondary battery is repeatedly charged and discharged, the active material layer 310 alternately shrinks and expands, causing separation between the active material layer 310 and the copper foil 101, thereby reducing the charge / discharge efficiency of the secondary battery. Particularly, the active material 310 containing silicon (Si) has a large degree of expansion and contraction.

According to another embodiment of the present invention, since the copper foil 101 used as the current collector can shrink and expand in response to contraction and expansion of the active material layer 310, the active material layer 310 can contract and expand The copper foil 101 is not deformed or torn. Thereby, separation does not occur between the copper foil 101 and the active material layer 310. Therefore, the secondary battery including the electrode 103 for the secondary battery has excellent charge / discharge efficiency and excellent capacity maintenance ratio.

4 is a schematic cross-sectional view of an electrode 104 for a secondary battery according to another embodiment of the present invention.

The electrode 104 for a secondary battery according to another embodiment of the present invention includes a copper foil 102 and active material layers 310 and 320 disposed on the copper foil 102. [ The copper foil 102 includes the copper foil 110 and the anticorrosive films 211 and 212 disposed on both sides of the copper foil 110. [

4 includes two active material layers 310 and 320 disposed on the first surface S1 and the second surface S2 of the copper foil 102, respectively. The active material layer 310 disposed on the first surface S1 of the copper foil 102 is referred to as a first active material layer and the active material layer 320 disposed on the second surface S2 of the copper foil 102 It may be referred to as a second active material layer.

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

5 is a schematic cross-sectional view of a secondary battery 105 according to another embodiment of the present invention. The secondary battery 105 shown in Fig. 5 is, for example, a lithium secondary battery.

5, the secondary battery 105 includes a cathode 370, an anode 340 disposed opposite to the anode 370, and an anode 340 disposed between the anode 370 and the cathode 340 An electrolyte 350 that provides an environment in which ions can move, and a separator 360 that electrically isolates the anode 370 from 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 from each other in order to prevent the charge generated from one electrode from being wasted by moving to the other electrode through the inside of the secondary battery 105. Referring to FIG. 5, a separation membrane 360 is disposed within the electrolyte 350.

The anode 370 includes a cathode current collector 371 and a cathode active material layer 372. An aluminum foil may be used for the positive electrode current collector 371.

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

As the anode current collector 341, the copper foils 101 and 102 disclosed in Figs. 1 or 2 may be used. The secondary battery electrodes 103 and 104 shown in FIG. 3 or 4 may be used as the cathode 340 of the secondary battery 105 shown in FIG.

Hereinafter, with reference to FIG. 6, a method of manufacturing the copper foil 102 according to another embodiment of the present invention will be described in detail.

6 is a schematic view of the manufacturing process of the copper foil 102 shown in Fig.

In order to produce the copper foil 102, the electrolytic solution 11 containing copper ions is first prepared. The electrolytic solution (11) is accommodated in the electrolytic bath (10).

Next, the positive electrode plate 13 and the rotating negative electrode drum 12, which are spaced apart from each other in the electrolyte solution 11 containing copper ions, are energized at a current density of 30 to 80 ASD (A / dm ² ) . The copper layer 110 is formed by the principle of electroplating. The distance between the positive electrode plate 13 and the rotating cathode drum 12 can be adjusted in the range of 8 to 13 mm.

When the current density applied between the positive electrode plate 13 and the rotating cathode drum 12 is less than 30 ASD, the generation of the crystalline particles of the copper layer 110 increases, and when the ASD exceeds 80 ASD, the microcrystallization of the crystalline particles accelerates. The current density can be adjusted above 40 ASD.

The surface characteristics of the shiny surface SS of the copper layer 110 may vary depending on the degree of buffing or polishing of the surface of the rotary cathode drum 12. [ The surface of the rotary cathode drum 12 can be polished with an abrasive brush having a grain size (Grit) of, for example, # 800 to # 3000 in order to adjust the surface properties in the direction of the shiny plane SS.

In the process of forming the copper layer 110, the electrolyte solution 11 is maintained at a temperature of 40 to 60 占 폚. More specifically, the temperature of the electrolytic solution 11 can be maintained at 50 DEG C or higher.

According to one embodiment of the present invention, the physical, chemical, and electrical properties of the copper layer 110 can be controlled by adjusting the composition of the electrolyte solution 11.

According to one embodiment of the present invention, the electrolyte 11 comprises 60 to 120 g / l of copper ions, 80 to 150 g / l of sulfuric acid, less than 50 ppm of chlorine (Cl) and organic additives.

The copper ion concentration and the sulfuric acid concentration in the electrolytic solution 11 are adjusted to 60 to 120 g / L and 80 to 150 g / L, respectively, so as to smooth the formation of the copper layer 110 by electrodeposition of copper.

Chlorine (Cl) includes both chloride ion (Cl < - >) and chlorine atoms present in the molecule. Chlorine (Cl) can be used, for example, to remove silver (Ag) ions introduced into the electrolyte 11 in the process of forming the copper layer 110. 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 50 ppm or more, unnecessary reaction due to excess chlorine (Cl) may occur. Therefore, the concentration of chlorine (Cl) in the electrolytic solution 11 is controlled to be 50 ppm or less. More specifically, the concentration of chlorine (Cl) can be controlled to be 25 ppm or less, for example, in the range of 5 to 25 ppm.

The electrolyte solution (11) contains an organic additive.

The organic additive includes at least one of a brightener (component A) and a retarder (component B) and a leveling agent (component C). That is, the organic additive may include any one of a brightening agent (component A) and a retarding agent (component B), and may include both a brightening agent (component A) and a retarding agent (component B). Further, the organic additive includes a leveling agent (component C).

The polishing agent (component A) includes a sulfonic acid or a metal salt thereof. The polishing agent (component A) can increase the charge amount of the electrolytic solution 11 to increase the electrodeposition rate of copper, improve the curl characteristic of the copper foil, and improve the gloss of the copper foil 102.

The polishing agent (component A) may have a concentration of 5 to 100 ppm in the electrolytic solution 11.

If the concentration of the polishing agent (component A) is less than 10 ppm, the gloss of the copper foil 102 is lowered. If the concentration is more than 100 ppm, the lightness of the copper foil 102 may be increased and the strength may be lowered.

More specifically, the brightener (component A) may have a concentration of 5 to 30 ppm in the electrolyte solution 11. [

The brightener may be, for example, bis- (3-sulfopropyl) -disulfide disodium salt (SPS), 3-mercapto-1-propanesulfonic acid, 3- N-dimethylthiocarbamoyl) -thiopropanesulfonate sodium salt, 3 - [(amino-iminomethyl) thio] -1-propanesulfonate sodium salt, o-ethyldithiocarbonate-S- -Sulfopropyl) -ester sodium salt, 3- (benzothiazolyl-2-mercapto) -propyl-sulfonate sodium salt and ethylenedithiodipropylsulfonic acid sodium salt. .

The slowing agent (component B) includes a nonionic water soluble polymer. The decelerator (component B) reduces the electrodeposition rate of copper, thereby preventing rapid increase in the roughness of the copper foil 102 and decrease in strength. These decelerating agents (component B) are also referred to as inhibitors or suppressors.

The decelerator (component B) may have a concentration of 5 to 50 ppm in the electrolytic solution 11.

If the concentration of the decelerating agent (component B) is less than 5 ppm, the roughness of the copper foil 102 sharply increases, and the strength of the copper foil 102 may be lowered. On the other hand, even if the concentration of the decelerator (component B) exceeds 50 ppm, the physical properties of the copper foil 102 such as appearance, gloss, roughness, strength, elongation and the like hardly change. Therefore, the concentration of the decelerator (component B) can be adjusted to a range of 5 to 50 ppm without unnecessarily raising the concentration of the decelerator (component B) to raise the manufacturing cost and waste of the raw material.

The slowing agent (component B) may be, for example, polyethylene glycol (PEG), polypropylene glycol, polyethylene polypropylene copolymer, polyglycerin, polyethylene glycol dimethyl ether, hydroxyethylene cellulose, polyvinyl alcohol, stearic acid polyglycol Ether and stearyl alcohol polyglycol ethers. ≪ RTI ID = 0.0 > [0031] < / RTI > However, the type of the retarder is not limited thereto, and other nonionic water-soluble polymers that can be used in the production of the high strength copper foil 102 may also be used as the decelerating agent.

The nonionic water soluble polymer used as the decelerating agent (component B) may have a number average molecular weight of 500 to 25,000. When the number average molecular weight of the decelerator (component B) is less than 500, the effect of preventing the rise of the roughness of the copper foil 102 due to the decelerating agent (component B) The formation of the copper layer 110 may not be easily performed due to the large molecular weight of the copper layer.

More specifically, the nonionic water-soluble polymer used as the decelerating agent (component B) may have a molecular weight of 1,000 to 10,000

The leveling agent (component C) includes at least one of nitrogen (N) and sulfur (S). That is, the leveling agent (component C) may contain one or more nitrogen atoms (N) or one or more sulfur atoms (S) in one molecule, and may contain one or more nitrogen atoms (N) May be included. For example, there is a chain type, a heterocyclic type, or an aromatic organic compound containing nitrogen (N) or sulfur (S) as a leveling agent (component C).

The leveling agent (C component) prevents excessive peaks or excessively large protrusions from being produced in the copper layer 110, so that the copper layer 110 becomes macroscopically flat.

The leveling agent (C component) may have a concentration of 1 to 50 ppm in the electrolyte solution (11).

When the concentration of the leveling agent (component C) is less than 1 ppm, the strength of the copper foil 102 is lowered, which makes it difficult to produce the high-strength copper foil 102. On the other hand, when the concentration of the leveling agent (component C) exceeds 50 ppm, the surface roughness of the copper foil 102 may excessively increase and the strength may be lowered. If the surface of the copper foil 102 is uneven, The copper foil 102 may be crushed and crushed, and the elongation of the copper foil 102 may be lowered.

More specifically, the leveling agent (component C) may have a concentration of 5 to 30 ppm in the electrolytic solution 11.

The leveling agent (component C) may be, for example, diallyldimethylammonium chloride (DDAC), thiourea, N, N'-dimethylthiourea, N, N'-diethylthiourea, tetramethylthiourea, Mercapto-5-benzimidazole sulfonic acid, 3 (5-mercapto-1H-tetrazole) benzenesulfonate, 2- mercaptobenzothiazole, 5-mercapto- ) And polyethyleneimine (PEI).

The organic additive may include two or more different leveling agents (component C).

Further, the organic additive may include at least one leveling agent (C component) including nitrogen (N) and at least one leveling agent (C component) including sulfur (S). The nitrogen (N) and sulfur (S) contained in the leveling agent are released to the grain structure of the copper layer 110 so that even after the heat treatment, the pin ) Effect. Accordingly, the copper foil 102 can have an excellent tensile strength even after the heat treatment.

The step of forming the copper layer 110 may include filtering the electrolyte solution 11. For the electrolytic solution 11 filtration, for example, the electrolyte 11 can be circulated at a flow rate of 35 to 45 m ³ / hour. Also, for cleanliness of the electrolyte solution 11, a Cu wire to be a raw material of the electrolyte solution 11 can be heat-treated and cleaned.

The thus-produced copper layer 110 can be cleaned in the cleaning tank 20. [

For example, acid cleaning for removing impurities such as resin components or natural oxide on the surface of the copper layer 110, and water cleaning for acidic solution used in pickling ) Can be performed sequentially. The cleaning process may be omitted.

Next, the anticorrosive films 211 and 212 are formed on the copper layer 110.

6, the copper layer 110 may be immersed in the rust preventive solution 31 contained in the anti-corrosion bath 30 to form the anticorrosive films 211 and 212 on the copper layer 110. [ The rust preventive liquid 31 may contain chromium. Chromium (Cr) can exist in the rust preventive liquid 31 in an ionic state.

The rust preventive liquid 31 may contain 1 to 10 g / L of chromium. For the formation of the anticorrosive films 211 and 212, the temperature of the anticorrosive solution 31 can be maintained at 20 to 40 占 폚. The copper layer 110 may be immersed in the rust preventive liquid 31 for about 1 to 30 seconds.

The anticorrosive films 211 and 212 may contain a silane compound by silane treatment or may contain a nitrogen compound by nitrogen treatment.

The copper foil 102 is formed by forming the antirust films 211 and 212.

Next, the copper foil 102 is cleaned in the cleaning tank 40. Such a cleaning process may be omitted.

Next, after the drying process is performed, the copper foil 102 is wound on the winder WR.

Hereinafter, the present invention will be described in detail with reference to production examples and comparative examples. However, the following production examples and comparative examples are provided only to aid understanding of the present invention, and the scope of the present invention is not limited by the production examples or the comparative examples.

Manufacturing example  1-4 and Comparative Example  1-4

A copper foil was manufactured by using a negative electrode plate including an electrolytic bath 10, a rotating negative electrode drum 12 disposed in the electrolytic bath 10, and a positive electrode plate 13 disposed apart from the rotating negative electrode drum 12. The electrolytic solution (11) is a copper sulfate solution. The copper ion concentration in the electrolytic solution 11 was 80 g / L, the sulfuric acid concentration was 100 g / L and the chlorine concentration was 20 ppm.

The electrolytic solution contains an organic additive. Bis (3-sulfopropyl) -disulfide disodium salt (SPS) was used as a brightener (component A), a polyethylene glycol (PEG) was used as a decelerator (component B) Diallyldimethylammonium chloride (DDAC), 5-mercapto-1-methyltetrazole (5MM) and polyethyleneimine (PEI) These contents (concentrations) are shown in Table 1 below.

The copper layer 110 was produced by applying a current between the rotating cathode drum 12 and the positive electrode plate 13 at a current density of 50 ASD while maintaining the temperature of the electrolyte at 55 占 폚. Next, the copper layer 110 was immersed in a rust-preventive solution containing chromium for about 2 seconds to perform chromate treatment on the surface of the copper layer 110 to form rust-preventive films 211 and 212. As a result, copper foils of Production Example 1-4 and Comparative Example 1-4 having a thickness of 6 mu m were produced.

Organic additive concentration (ppm) SPS
(Component A) PEG
(Component B) DDAC
(Component C) 5MM
(Component C) PEI
(Component C) Production Example 1 20 30 30 - - Production Example 2 20 30 - 30 - Production Example 3 20 30 20 20 - Production Example 4 20 30 20 - 20 Comparative Example 1 20 - - - - Comparative Example 2 - 30 - - - Comparative Example 3 20 30 - - - Comparative Example 4 - - - - 20

SPS: Bis (3-Sulfo-Propyl) di-Sulfide

PEG: Polyethylene Glycol

DDAC: Diallyldimethylammonium chloride

5MM: 5-Mercapto-1-methyltetrazole

PEI: Polyethyleneimine

(I) tensile strength after heat treatment at room temperature and 190 ° C for 1 hour (ii) average thermal grains after heat treatment at room temperature and 190 ° C for 1 hour, and Particle size, (iii) curl, (iv) surface roughness and (v) elongation were measured.

Further, the secondary battery was manufactured using the copper foil, and the secondary battery was charged and discharged (vi), the capacity retention rate was evaluated, and (vii) the secondary battery was disassembled to observe whether or not the copper foil was broken.

(i) Tensile strength measurement

The tensile strength at room temperature of the copper foil was measured at room temperature (25 占 15 占 폚), and the high temperature tensile strength of the copper foil was measured after the copper foil was heat treated at 190 占 폚 for 1 hour.

Specifically, the tensile strength was measured using an Instron universal testing machine (UTM) according to the IPC-TM-650 Test Method Manual. The width of the sample for tensile strength measurement was 12.7 mm, the distance between the grips was 50 mm, and the measurement speed was 50 mm / min.

(ii) the average particle size of the crystalline particles

The average particle size of the crystalline particles contained in the copper layer constituting the copper foil was measured at room temperature (25 ± 15 ° C), and the average particle size of the crystalline particles contained in the copper layer was measured after the copper foil was heat- Respectively.

The first and second faces S1 and S2 of the copper foil were analyzed according to the Electron Back Scattered Diffraction (EBSD) method, and the average particle size of the crystalline particles was calculated using the analysis results. Specifically, a device equipped with an EBSD (Electron Backscatter Diffraction) detector (eg, EDAX EBSD camera) is mounted on a Field Emission-Scanning Electron Microscope (FE-SEM) The average particle size of the crystalline particles contained in the copper layer 110 was measured by observing the cross section of the copper foil 101 under the measurement conditions of a voltage of 15 kV, a current of 50 mA and a magnification of 2000 times.

(iii) curl measurement

For the curl measurement of the copper foil 101, the copper foils of Production Example 1-4 and Comparative Example 1-4 were cut to 60 mm X 60 mm to prepare a copper foil specimen 510. 7 is a schematic view for explaining curl measurement of the copper foil.

7, a specimen 510 is placed on a supporter 520 such that the first surface S1 of the specimen 510 faces upward, and then a glass plate 530 is placed on the specimen 510. As shown in FIG. At this time, only the 30 mm length of the specimen was overlapped with the glass plate so that only half of the specimen 510 was positioned between the support plate 520 and the glass plate 530 and the other half was exposed from the glass plate 530. The height of the specimen 510 exposed outside the glass plate 530 was measured using the measuring unit 540 (meter scale), and the maximum height thereof was defined as a curl height value of the copper foil.

Four specimens 510 were prepared for each of the copper foils of Production Examples 1-4 and 1-4, and the flexural height was measured. The curl height value of the copper foil was calculated by calculating the average value.

(iv) Surface roughness (Rz JIS) measurement

(S1) and the second surface (S2) of the copper foil prepared in Production Examples 1-4 and Comparative Examples 1-4 were measured using a surface roughness meter (M300, Mahr) according to JIS B 0601-2001 And surface roughness (Ra) were respectively measured.

(v) elongation measurement

The elongation was measured by a universal testing machine (UTM) according to the IPC-TM-650 Test Method Manual. Specifically, the elongation was measured using an universal testing machine manufactured by Instron. The width of the sample for elongation measurement was 12.7 mm, the distance between the grips was 50 mm, and the measurement speed was 50 mm / min.

(vi) Capacity retention rate evaluation

1) Negative electrode manufacturing

2 parts by weight of styrene butadiene rubber (SBR) and 2 parts by weight of carboxymethyl cellulose (CMC) were mixed with 100 parts by weight of a commercially available silicon / carbon composite anode active material for a negative electrode active material and distilled water was used as a solvent to prepare a slurry . Slurry for negative electrode active material was applied on the copper foil of Production Examples 1-4 and Comparative Example 1-4 having a width of 10 cm using a doctor blade to a thickness of 20 to 60 탆, dried at 120 캜, ² < / RTI > was applied to produce a negative electrode for a secondary battery.

2) Manufacture of electrolytic solution

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

 3) Anode manufacturing

Lithium manganese oxide of Li _1.1 Mn _1.85 Al _0.05 O ₄ and lithium manganese oxide of orthorhombic crystal structure of o-LiMnO ₂ were mixed at a ratio of 90:10 (weight ratio) to prepare a cathode active material. The cathode active material, carbon black, and PVDF [poly (vinylidenefluoride)] as a binder were mixed at a weight ratio of 85: 10: 5 and mixed with NMP as an organic solvent to prepare a slurry. The slurry thus prepared was coated on both sides of an aluminum foil having a thickness of 20 탆 and dried to prepare a positive electrode.

4) Manufacture of lithium secondary battery for test

A lithium secondary battery in the form of a coin was produced by disposing an anode and a cathode in the aluminum can to insulate the aluminum can from each other, and arranging a non-aqueous electrolyte and a separator therebetween. The separator used was polypropylene (Celgard 2325; thickness 25 μm, average pore size 28 nm, porosity 40%).

5) Capacity retention rate evaluation

Using the thus prepared lithium secondary battery, the capacity per g of the positive electrode was measured by driving the cell at a charge voltage of 4.3 V and a discharge voltage of 3.4 V. Next, to evaluate the high-temperature lifetime, 50 charge / discharge experiments were performed at a high temperature of 50 ° C at a current rate (C-rate) of 50 C to calculate the capacity retention rate. The capacity retention rate can be calculated by the following equation (1).

[Formula 1]

Capacity retention rate (%) = [(50 times charge / discharge capacity) / (1 charge / discharge charge capacity)] x 100

The capacity retention rate was measured three times and the average value was adopted. When the capacity retention rate is less than 90%, it is determined that the copper foil is unsuitable as a negative electrode current collector for a lithium ion battery

(vii) Observe whether or not the copper foil is broken.

After 50 charge / discharge cycles, the secondary battery was disassembled and it was observed whether or not the copper foil was broken. The case where breakage was issued to the copper foil was indicated as " 0 ", and the case where breakage was not occurred was indicated as " X ".

The results of the above tests are shown in Table 2. However, since the copper foils of Production Example 1-4 and Comparative Example 1-4 were measured to have an elongation of mode 2% or more, the elongation was excluded in Table 2.

The tensile strength
(㎏f / mm ²⁾ Average particle size
(탆) Surface roughness
(Rz JIS) Curl
(Mm) Capacity retention rate
(%) Occurrence of breakage Room temperature High temperature Room temperature High temperature The first side Second side Difference Production Example 1 41 37 1.1 1.4 1.1 0.9 0.2 8 91 x Production Example 2 43 40 1.2 1.5 1.0 0.9 0.2 14 90 x Production Example 3 50 48 0.9 1.1 1.1 1.0 0.1 11 92 x Production Example 4 52 49 0.8 0.9 1.3 0.9 0.4 9 91 x Comparative Example 1 33 29 3.2 4.7 1.2 1.0 0.2 17 79 o Comparative Example 2 55 35 1.7 3.3 1.7 0.9 0.8 25 73 o Comparative Example 3 33 27 3.4 4.5 1.5 0.9 0.6 19 82 o Comparative Example 4 45 30 1.9 3.7 1.6 1.0 0.6 32 75 o

Referring to Tables 1 and 2, the following results are obtained.

A curl exceeding 15 mm occurred in the copper foil of Comparative Example 1 made of an electrolytic solution containing only the polish (A component) and the electrolytic solution not containing the decelerating agent (B component) and the leveling agent (C component) The secondary battery produced using the copper foil of Example 1 had a capacity retention rate of less than 90% and fracture occurred in the copper foil.

A curl exceeding 15 mm occurred in the copper foil of Comparative Example 2, which was made of an electrolytic solution containing only a decelerating agent (component B) and not containing a polish (component A) and a leveling agent (component C) The secondary battery produced using the copper foil of Example 2 had a capacity retention rate of less than 90% and fracture occurred in the copper foil.

A curl exceeding 15 mm occurred in the copper foil of Comparative Example 3 made of an electrolytic solution containing a polish (A component) and a decelerating agent (B component) and not containing a leveling agent (C component) in the organic additive, The secondary battery produced using the copper foil of Example 3 had a capacity retention rate of less than 90% and fracture occurred in the copper foil.

A curl exceeding 15 mm occurred in the copper foil of Comparative Example 4 which was made of an electrolyte containing only a leveling agent (C component) and not containing a polish (A component) and a decelerator (B component) The secondary battery produced using the copper foil of Example 4 had a capacity retention rate of less than 90% and fracture occurred in the copper foil.

On the other hand, according to one embodiment of the present invention, in Examples 1 to 4 (Comparative Examples 1 to 4) made of an electrolytic solution containing at least one of a brightener (component A) and a retarder (component B) The height of the curl in the copper foil of the present invention is 15 mm or less, and the secondary battery produced by using such a copper foil has a capacity retention rate of 90% or more, and the copper foil does not break.

In the case of Comparative Examples 2 to 4 , the difference in surface roughness (Rz JIS) between both surfaces of the copper foil is 0.5 mu m or more.

Figs. 8A and 8B show cross sections of the copper foil according to Production Example 3 before and after the heat treatment, respectively, and Figs. 9A and 9B show cross sections of the copper foil according to Comparative Example 3 before and after the heat treatment, respectively. 8A, 8B, 9A and 9B, the upward direction of the drawing is the direction of the matte surface MS and the downward direction of the drawing is the direction of the shiny surface SS.

Referring to FIG. 8A, in the copper foil according to Production Example 3, the average particle size of the crystalline particles of the copper layer before heat treatment is 0.9 μm on the basis of the particle diameter, and referring to FIG. 8B, after the heat treatment at 190 ° C. for 1 hour, The average particle size of the particles is 1.1 mu m on the basis of the particle diameter. Thus, in the copper foil according to Production Example 3, the average particle size of the crystalline particles of the copper layer before and after the heat treatment is in the range of 0.7 to 1.5 占 퐉 on the basis of the particle size.

9A, on the copper foil of Comparative Example 3, the average particle size of the crystalline particles of the copper layer before heat treatment is 3.4 μm on the basis of the particle diameter, and referring to FIG. 9B, after the heat treatment for 1 hour at 190 ° C., Of the average particle size of the crystalline particles is 4.5 mu m on the basis of the particle diameter. In the copper foil of Comparative Example 3, the average particle size of the crystalline particles of the copper layer before and after the heat treatment exceeded 1.5 占 퐉 on the basis of the particle size.

Particularly, it can be confirmed that the average grain size of the crystal grains of the copper layer after the heat treatment in Comparative Examples 1, 2 and 4, as well as Comparative Example 3, increased by 1 占 퐉 or more compared to that before the heat treatment.

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 or scope of the invention. To those skilled in the art. Therefore, the scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning, scope and equivalents of the claims are to be construed as being included in the scope of the present invention.

101, 102: copper foil
211, 212: Antirust film
310, 320: active material layer
103, 104: electrode for secondary battery
MS: Matte cotton
SS: Shiny Face

Claims (19)

A copper layer having a matte surface and a shiny surface; And
And a rust preventive film disposed on the copper layer,
40 to room temperature (25 ± 15 ℃) tensile strength of 60kgf / mm ^2; And
At 190 ℃ 1 hour after the heat treatment, a high temperature tensile strength of 36 to 55kgf / mm ^2; having a,
Wherein the copper layer has crystalline particles and the crystalline particles after heat treatment at room temperature and 190 占 폚 for 1 hour have an average particle size of 0.7 to 1.5 占 퐉. The method according to claim 1,
A copper foil having a maximum curl height of 15 mm or less. The method according to claim 1,
A first surface in the matte surface direction and a second surface in the shiny surface direction,
Wherein the first surface and the second surface each have a surface roughness (Rz JIS) of 0.5 to 2.0 mu m. The method according to claim 1,
A copper foil having a thickness of 4 to 35 μm. The method according to claim 1,
Wherein the rustproofing film comprises at least one of chromium, a silane compound and a nitrogen compound. Copper foil; And
And an active material layer disposed on at least one side of the copper foil,
Wherein the copper foil is a copper foil according to any one of claims 1 to 5,
Electrode for secondary battery. A cathode;
An anode disposed opposite to the anode;
An electrolyte disposed between the anode and the cathode to provide an environment in which lithium ions can move; And
And a separator for electrically insulating the anode and the cathode,
The negative electrode,
The copper foil according to any one of claims 1 to 5, And
An active material layer disposed on the copper foil;
And a secondary battery. A positive electrode plate and a rotating negative electrode arranged to be spaced apart from each other in an electrolytic solution containing copper ions, at a current density of 30 to 80 ASD (A / dm < ² >) to form a copper layer,
The electrolyte solution,
60 to 120 g / L of copper ions;
80 to 150 g / L sulfuric acid;
Less than 50 ppm chlorine (Cl); And
An organic additive,
The organic additive may include,
At least one selected from a brightener (component A) and a retarder (component B); And
A leveling agent (component C)
The brightener (component A) comprises a sulfonic acid or a metal salt thereof,
Wherein the retarder (component B) comprises a nonionic water-soluble polymer,
Wherein the leveling agent (C component) comprises at least one of nitrogen (N) and sulfur (S)
A method of manufacturing a copper foil. 9. The method of claim 8,
Wherein in the step of forming the copper layer, the temperature of the electrolytic solution is maintained in the range of 40 to 60 占 폚. 9. The method of claim 8,
Wherein the brightener has a concentration of 5 to 100 ppm. 9. The method of claim 8,
The polish may be selected from the group consisting of bis- (3-sulfopropyl) -disulfide disodium salt (SPS), 3-mercapto-1-propanesulfonic acid, 3- -Dimethylthiocarbamoyl) -thiopropanesulfonate sodium salt, 3 - [(amino-iminomethyl) thio] -1-propanesulfonate sodium salt, o-ethyldithiocarbonate-S- ) -Ester sodium salt, 3- (benzothiazolyl-2-mercapto) -propyl-sulfonic acid sodium salt and ethylenedithiodipropylsulfonic acid sodium salt. . 9. The method of claim 8,
Wherein the retarder has a concentration of 5 to 50 ppm. 9. The method of claim 8,
The decelerator may be selected from the group consisting of polyethylene glycol (PEG), polypropylene glycol, polyethylene polypropylene copolymer, polyglycerin, polyethylene glycol dimethyl ether, hydroxyethylene cellulose, polyvinyl alcohol, stearic acid polyglycol ether and stearyl alcohol polyglycol Ether and at least one nonionic water-soluble polymer selected from the group consisting of an ether and a nonionic water-soluble polymer. 14. The method of claim 13,
Wherein the nonionic water soluble polymer has a number average molecular weight of 500 to 25,000. 9. The method of claim 8,
Wherein the leveling agent has a concentration of 1 to 50 ppm. 9. The method of claim 8,
The leveling agent may be at least one selected from the group consisting of diallyldimethylammonium chloride (DDAC), thiourea, N, N'-dimethylthiourea, N, N'-diethylthiourea, tetramethylthiourea, Mercapto benzothiazole, 5-mercapto-1-methyl tetrazole (5-MM) and polyethyleneimine (5-mercapto- PEI). ≪ / RTI > 9. The method of claim 8,
Wherein the organic additive comprises two or more different leveling agents (component C). 9. The method of claim 8,
Wherein the organic additive comprises at least one leveling agent (C component) comprising nitrogen (N) and at least one leveling agent (C component) comprising sulfur (S). 9. The method of claim 8,
And forming a rustproof film on the copper layer.

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