WO2017123034A1

WO2017123034A1 - Copper foil, method for manufacturing same, electrode comprising same, and secondary battery comprising same

Info

Publication number: WO2017123034A1
Application number: PCT/KR2017/000450
Authority: WO
Inventors: 김승민
Original assignee: 엘에스엠트론 주식회사
Priority date: 2016-01-13
Filing date: 2017-01-13
Publication date: 2017-07-20

Abstract

Disclosed are a copper foil capable of securing a secondary battery having a high capacity retention rate, a method for manufacturing the same, an electrode comprising the same, and a secondary battery comprising the same. In the present invention, the copper foil for the secondary battery has a first surface and a second surface located opposite to the first surface, wherein each of the first and second surfaces has 1 to 8 macro protrusions per 5㎛ when the cross sections thereof are observed in EBSD pictures.

Description

Copper foil, the manufacturing method, the electrode containing the same, and the secondary battery containing the same

The present invention relates to a copper foil, a method for producing the same, an electrode including the same, and a secondary battery including the same.

A secondary battery is a type of energy conversion device that generates electricity by converting electrical energy into a form of chemical energy and storing the converted energy when the electricity is needed. battery).

Secondary batteries which have economic and environmental advantages over disposable primary batteries include lead storage batteries, nickel cadmium secondary batteries, nickel hydrogen secondary batteries, and lithium secondary batteries.

Lithium secondary batteries can store more energy relative to size and weight than other secondary batteries. Therefore, in the field of information and communication devices where portability and mobility are important, lithium secondary batteries are preferred, and their application ranges are expanding as energy storage devices of hybrid vehicles and electric vehicles.

Lithium secondary batteries are used repeatedly with one cycle of charging and discharging. When operating a device with a fully charged lithium secondary battery, the lithium secondary battery must have a high charge / discharge capacity in order to increase the operating time of the device. Therefore, there is a continuous demand for research to satisfy the demands of increasing daily demand for charge / discharge capacities of lithium secondary batteries.

However, even if the secondary battery has a sufficiently high charge / discharge capacity, if the charge / discharge capacity of the secondary battery decreases rapidly as the charge / discharge cycle is repeated (that is, if the capacity retention rate is low or the life is short), the consumer Will require frequent replacement of the secondary battery, resulting in consumer inconvenience and waste of resources.

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

One aspect of the present invention is to provide a copper foil capable of securing 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.

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.

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

According to one aspect of the present invention, a copper foil for a secondary battery having a first surface and a second surface opposite thereto, the copper film having a mat surface facing the first surface and a shiny surface facing the second surface; A first copper protrusion layer on the mat surface of the copper film; A first protective layer on the first copper protrusion layer; A second copper protrusion layer on the shiny surface of the copper film; And a second protective layer on the second copper protrusion layer, and when the cross-section of the copper foil for secondary batteries is observed with an Electron Backscattered Diffraction (EBSD) photograph, each of the first and second surfaces is 1 to 8 per 5 μm. Characterized in that it has two giant protuberances, wherein said giant protrusions are said first ones of points on valleys and pores formed on or near said first or second side. A copper foil for a secondary battery is provided, which is a projection projecting more than 0.7 μm from a reference line horizontally spaced from the first or second surface and passing through a point most separated from the second surface.

According to another aspect of the invention, the step of manufacturing a copper film having a mat surface and a shiny surface; Forming a first copper projection layer and a second copper projection layer on the mat surface and the shiny surface of the copper film, respectively; And forming a first protective layer and a second protective layer on the first copper protrusion layer and the second copper protrusion layer, respectively, wherein the forming of the first and second copper protrusion layers is performed on the copper. Is performed by sequentially passing two or more nucleation plating baths and two or more nucleation plating baths, and the total current applied through the nucleation plating baths to the total current applied through the nucleation plating baths. Ratio is 0.2-2, The manufacturing method of the copper foil for secondary batteries is provided.

According to still another aspect of the present invention, there is provided a copper foil having a first surface and a second surface opposite thereto; And an active material layer on at least one of the first and second surfaces of the copper foil, wherein the copper foil includes: a copper film having a mat surface facing the first surface and a shiny surface facing the second surface; A first copper protrusion layer on the mat surface of the copper film; A first protective layer on the first copper protrusion layer; A second copper protrusion layer on the shiny surface of the copper film; And a second protective layer on the second copper protrusion layer, wherein when the cross section of the copper foil is observed in an EBSD photograph, each of the first and second faces has 1 to 8 large protrusions per 5 μm. Wherein the coarse protrusion passes through the most distant point from the first or second face of the points on the valleys and pores formed at or near the first or second face. An electrode is provided, which is a protrusion protruding at least 0.7 μm from a reference line horizontal with the first or second face.

According to another aspect of the invention, a cathode (cathode); An anode; An electrolyte providing an environment in which lithium ions may move between the positive electrode and the negative electrode; And a separator that electrically insulates the anode and the cathode, the cathode comprising: a copper foil having a first surface and a second surface opposite thereto; And an active material layer on at least one of the first and second surfaces of the copper foil, wherein the copper foil includes: a copper film having a mat surface facing the first surface and a shiny surface facing the second surface; A first copper protrusion layer on the mat surface of the copper film; A first protective layer on the first copper protrusion layer; A second copper protrusion layer on the shiny surface of the copper film; And a second protective layer on the second copper protrusion layer, wherein when the cross section of the copper foil is observed in an EBSD photograph, each of the first and second faces has 1 to 8 large protrusions per 5 μm. Wherein the coarse protrusion passes through the most distant point from the first or second face of the points on the valleys and pores formed at or near the first or second face. A secondary battery is provided, wherein the projection protrudes 0.7 µm or more from a reference line horizontal to the first or second surface.

The general description of the present invention as described above is only for illustrating or explaining the present invention, and does not limit the scope of the present invention.

According to the present invention, a long-life secondary battery capable of maintaining a high charge / discharge capacity for a long time despite repeated charge / discharge cycles can be manufactured. Therefore, it is possible to minimize the inconvenience and resource waste of consumer electronics due to frequent replacement of the secondary battery.

The accompanying drawings are included to assist in understanding the present invention and to form a part of the specification, to illustrate embodiments of the present invention, and to explain the principles of the present invention together with the detailed description of the invention.

1 is a cross-sectional view of a secondary battery copper foil according to an embodiment of the present invention,

2 is an EBSD photograph of a cross section of a copper foil for secondary batteries according to an embodiment of the present invention;

Figure 3 shows an apparatus for manufacturing a secondary battery copper foil according to an embodiment of the present invention,

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

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention;

It will be apparent to those skilled in the art that various changes and modifications of the present invention are possible without departing from the spirit and scope of the present invention. Accordingly, the invention includes all modifications and variations that fall within the scope of the invention as set forth in the claims and their equivalents.

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

As illustrated in FIG. 1, the copper foil 100 of the present invention having the first surface 100a and the second surface 100b opposite thereto has a mat surface facing the first surface 100a. Copper film 110 having a shiny surface 110b facing 110a and the second surface 100b, and first copper on the mat surface 110a of the copper film 110. The protrusion layer 121, the first protective layer 131 on the first copper protrusion layer 121, the second copper protrusion layer 122 on the shiny surface 110b of the copper film 110, and the first agent. The second protective layer 132 on the two copper protrusion layer 122 is included.

Since the copper foil 100 of the present invention has a symmetrical structure with respect to the copper film 110, the copper foil 100 may be prevented or minimized in one direction.

The copper film 110 may be formed on the rotating cathode drum through electroplating. The shiny surface 110b of the copper film 110 may be a surface in contact with the rotating cathode drum, and the mat surface 110a may be formed on the rotating cathode drum. The opposite side is the opposite. The copper film 110 of the present invention may include 99 wt% or more copper.

Alternatively, the copper film 110 may be manufactured through rolling. For convenience of description, the copper film 110 manufactured by rolling also refers to one surface as the mat surface 110a and the other surface as the shiny surface 110b.

By forming an active material layer on the copper foil 100 of the present invention, a negative electrode for a secondary battery may be manufactured.

As charging and discharging of the secondary battery is repeated, contraction and expansion of the active material layer alternately occur, which causes separation of the active material layer and the copper foil 100, thereby lowering the charge and discharge efficiency of the secondary battery. Therefore, in order for the secondary electrode to secure a capacity retention rate and a lifespan of a predetermined level or more (that is, to suppress a decrease in charge / discharge efficiency of the secondary battery), the copper foil 100 has excellent coating property with respect to the active material. The adhesive strength of the (100) and the active material layer should be high.

In order to coat the active materials on the first and

second surfaces

100a and 100b of the copper foil 100, it is most ideal for the stability of the secondary battery that their surface areas remain the same. Therefore, it is preferable that the first and

second surfaces

100a and 100b of the copper foil 100 have the same or similar 10-point average roughness R _zJIS .

From a macro perspective, the smaller the 10-point average roughness R _zJIS of the first and

second surfaces

100a and 100b of the copper foil 100 is, the better the charge and discharge efficiency of the secondary battery including the copper foil 100 is. This tends to be less degraded in general.

Therefore, each of the first and

second surfaces

100a and 100b of the copper foil 100 according to the exemplary embodiment of the present invention has a ten point average roughness R _zJIS of 0.2 to 0.8 μm.

If the first and

second surfaces

100a and 100b of the copper foil 100 have a ten-point average roughness R _zJIS of less than 0.2 μm, the surface area of the copper foil 100 is relatively small, and thus the active material is copper foil 100. Easily detached from, resulting in a sudden decrease in the life of the secondary battery due to repeated charging and discharging.

On the other hand, if the first and

second surfaces

100a and 100b of the copper foil 100 have a ten-point average roughness R _zJIS exceeding 0.8 μm, the contact uniformity between the copper foil 100 and the active material layer is It does not reach this certain level, and a plurality of spaces exist between the copper foil 100 and the active material layer (that is, the coating itself is not partially formed), and as a result, the rapid life of the secondary battery due to repeated charge and discharge Deterioration is caused.

However, even if the first and second surfaces (100a, 100b) of the copper foil 100 to have a ten-point average roughness (R _zJIS) of 0.2 to 0.8 ㎛, such a copper foil 100 is necessarily 90% or more secondary batteries Capacity retention cannot be guaranteed. That is, the 10-point average roughness R _zJIS of 0.2 to 0.8 μm of the first and

second surfaces

100a and 100b of the copper foil 100 may not be sufficient conditions for the secondary battery capacity retention rate of 90% or more.

As a result of repeated studies, the Applicant has found that the number of giant protuberances (GP) present on the first and

second surfaces

100a and 100b of the copper foil 100 in securing a capacity retention rate of 90% or more. Is an important factor.

Hereinafter, referring to FIG. 2, the giant protrusion GP present in the first and

second surfaces

100a and 100b of the copper foil 100 of the present invention will be described in detail. 2 is an EBSD photograph showing a cross section of a secondary battery copper foil 100 according to an embodiment of the present invention, more specifically, a cross section near the first surface 100a.

According to the present invention, the first and second copper protrusion layers 121 and 122 are formed on the mat surface 110a and the shiny surface 110b of the copper film 110, respectively. Large protrusions GP are present on the first and

second surfaces

100a and 100b. The first and second copper protrusion layers 121 and 122 may include 98 wt% or more copper.

In the present specification, the giant protrusion GP may include the first of the points on the valleys and pores formed at or near the first or

second surfaces

100a and 100b of the copper film 110. Or a protrusion protruding from the second surface (100a, 100b) the most spaced apart from the reference line (BL) horizontal to the first or second surface (100a, 100b) or more than 0.7㎛.

According to the present invention, when the cross section of the secondary battery copper foil 100 is observed with an EBSD photograph, each of the first and

second surfaces

100a and 100b of the copper foil 100 may have 1 to 8 large protrusions per 5 μm ( GP).

When the number of macroscopic projections (GP) per 5 μm is zero, this decreases the adhesion between the copper foil 100 and the active material due to the lack of contact area between the copper foil 100 and the active material layer, and as a result, the charge and discharge may be repeated. A sudden decrease in life of the secondary battery is caused.

On the other hand, even when the number of giant projections (GP) per 5 μm is 9 or more, capacity retention of the secondary battery may be deteriorated due to repetition of charging and discharging. The first and

second surfaces

100a and 100b may not be in close contact with each other, and thus an empty space may be generated. For this reason, as the number of charge and discharge increases, the amount of the active material detached from the copper foil 100 increases, and the life of the secondary battery is drastically reduced.

According to an embodiment of the present invention, since the active material is coated on both the first and

second surfaces

100a and 100b of the copper foil 100, the first and

second surfaces

100a and 100b of the copper foil 100 are coated. It is preferable that the difference in the number of the giant protrusions GP present in each) is 6 or less. If the number difference exceeds six, the capacity retention ratio of the secondary battery may be deteriorated due to the difference in the surface shape of the first and

second surfaces

100a and 100b.

As described above, the copper foil 100 of the present invention further includes first and second

protective layers

131 and 132 formed on the first and second copper protrusion layers 121 and 1222, respectively.

The first and second

protective layers

131 and 132 may be formed by coating or electrodepositing anticorrosion material on the first and second copper protrusion layers 121 and 1222, respectively. The rust preventive material may include at least one of chromate, benzotriazole (BTA), and a silane compound. The first and second

protective layers

131 and 132 may prevent oxidation and corrosion of the copper film 110, the first copper protrusion layer 121, and the second copper protrusion layer 122, and may improve heat resistance. By doing so, the life of the secondary battery including the same, as well as the life of the copper foil 100 itself.

According to one embodiment of the invention, the copper film 110 has a thickness of 2 to 34 ㎛, the secondary battery copper foil 100 has a thickness of 4 to 35 ㎛. The copper foil 100 having a thickness of less than 4 μm is easily torn at the time of manufacturing a secondary battery, causing workability deterioration. On the other hand, when the secondary battery is manufactured with the copper foil 100 exceeding 35 μm, high capacity becomes difficult due to the thick copper foil 100.

Copper foil 100 according to an embodiment of the present invention has a room temperature tensile strength of 28 to 65 kgf / mm ² , high temperature tensile strength of 25 kgf / mm ² or more, and an elongation of 3 to 13%. As used herein, the term "normal tensile strength" refers to tensile strength measured at room temperature, and the term "high-temperature tensile strength" refers to tensile strength measured after heat treatment at 135 ° C for 10 minutes.

If the room temperature tensile strength of the copper foil 100 is less than 28 kgf / mm ² , wrinkles may be caused to the copper foil 100 in a roll-to-roll process for manufacturing a secondary battery. On the other hand, when the room temperature tensile strength of the copper foil 100 exceeds 65 kgf / mm ² , the elongation of the copper foil 100 is lowered, causing breakage of the copper foil 100 during the manufacture of a secondary battery. A secondary battery made of a copper foil 100 having wrinkles or breaks has a problem in that the capacity retention rate is lowered to less than 80% during 50 charge / discharge cycles.

Meanwhile, the high temperature tensile strength of the copper foil 100 should be 25 kgf / mm ² or more, so that softening does not occur during the roll press process and / or the drying process, and the handling property degradation due to wrinkles may be prevented.

As described above, the copper foil 100 of the present invention having high room temperature tensile strength and high temperature tensile strength includes an active material (eg, a composite active material in which Si or Sn is added to a carbon active material) capable of increasing secondary battery capacity. Even if it expands severely during charging and / or discharging, it can withstand the thermal expansion of the active material sufficiently to improve the life and reliability of the secondary battery, as well as on the copper foil 100 of the present invention to manufacture the secondary battery electrode When coating the active material, workability deterioration due to warpage of the copper foil 100 may be prevented.

On the other hand, the copper foil 100 according to an embodiment of the present invention has an elongation of 3 to 13%. If the elongation is less than 3%, there is a risk of breaking the copper foil 110 during expansion and contraction of the active material. On the other hand, when the elongation exceeds 13%, the copper foil 100 easily stretches during the secondary battery manufacturing process, causing deformation of the electrode. The secondary battery manufactured from the broken or deformed copper foil 100 has a problem that the capacity retention rate is lowered to less than 80% during 50 charge / discharge cycles.

Hereinafter, a manufacturing method of the secondary battery copper foil 100 according to an embodiment of the present invention will be described in detail with reference to FIG. 3.

The method of the present invention comprises the steps of manufacturing a copper film 110 having a mat surface (110a) and a shiny surface (110b), a first surface on the mat surface (110a) and the shiny surface (110b) of the copper film (110) Forming a copper protrusion layer 121 and a second copper protrusion layer 122, and a first protective layer 131 on the first copper protrusion layer 121 and the second copper protrusion layer 122. And forming second protective layers 132, respectively.

According to one embodiment of the present invention, the anode plate 13 and the rotating cathode drum 12 which are spaced apart from each other in the electrolyte solution 11 of the electrolytic cell 10 are energized at a current density of 40 to 80 A / dm ² . The copper film 110 is electrodeposited on the rotary cathode drum 12.

The electrolyte solution 11 may include 50 to 100 g / L of copper ions, 50 to 150 g / L of sulfuric acid, 50 ppm or less of chlorine ions, and an organic additive. The organic additive may be hydroethyl cellulose (HEC), organic sulfide, organic nitride, or a mixture of two or more thereof. The electrolyte solution 11 may be maintained at 40 to 60 ℃ during the electroplating.

As described above, the roughness of the shiny surface 110b of the copper film 110 is affected by the degree of polishing of the surface of the rotary cathode drum 12 (that is, the surface where copper is deposited by electroplating). According to one embodiment of the present invention, the surface of the rotary cathode drum 12 may be polished with a polishing brush having a particle size (Grit) of # 800 to # 1500.

According to the present invention, in order to maintain the concentrations of organic impurities and metal impurities in the electrolyte solution 11 or less and 3 g / L or less, respectively, in the electroplating, a high purity copper wire is applied to the electrolyte solution 11. Before the addition, the organic material is burned by heat treatment at a high temperature of 600 to 800 ° C. (for example, about 700 ° C.), followed by acid cleaning with an acid such as sulfuric acid.

In addition, while conducting electroplating by energizing the positive electrode plate 13 and the rotary cathode drum 12 while the pickled copper wire is introduced into the electrolyte solution 11, organic impurities and metals from the electrolyte solution 11 are performed. By performing continuous filtration to remove solid impurities including impurities, the concentrations of organic impurities and metal impurities in the electrolyte solution 11 are maintained at 1 g / L or less and 3 g / L or less, respectively. In this case, the flow rate of the electrolyte solution 11 supplied to the electrolytic cell 10 may be 30 to 50 m ³ / hour.

Subsequently, the copper film 110 is sequentially passed through two or more

nucleation plating baths

20 and 30 and two or more nucleation

growth plating baths

40 and 50, thereby providing a mat of the copper film 110. First and second copper protrusion layers 121 and 122 are formed on the surface 110a and the shiny surface 110b, respectively.

The

electrolytes

21 and 31 of the

nucleation plating baths

20 and 30 may contain 8 to 25 g / L of copper ions, 50 to 160 g / L of sulfuric acid, and 0.05 to 1 g / L of the first additive. Wherein the

electrolytic solutions

41 and 51 of the nuclear

growth plating baths

40 and 50 comprise 30 to 70 g / L copper ions, 50 to 160 g / L sulfuric acid, and 0.03 to 1.2 g / L Two additives, each of the first and second additives may be Fe, Mo, W, V, Co, Cr, Mn, Zn, or a mixture of two or more thereof.

According to the present invention, the total current i _{c_total} applied through the

nucleation plating baths

20 and 30 is 3000 to 7000 A, and the total current applied through the

nucleation plating baths

20 and 30. the ratio of the total current (i _{g_total)} is applied over the nuclei grow in the plating bath (40, 50) for (i _{c_total)} from 0.2 to 2.

When the ratio of the total current is less than 0.2, when the cross section of the final copper foil 100 is observed in the EBSD photograph, the giant protrusion GP does not exist on the first and

second surfaces

100a and 100b. On the other hand, when the ratio of the total current exceeds 2, each of the first and

second surfaces

100a and 100b of the copper foil 100 has nine or more giant protrusions GP per 5 μm.

As described above, when the number of macroscopic projections (GP) per 5 μm is zero, the adhesion between the copper foil 100 and the active material is lowered due to the lack of contact area between the copper foil 100 and the active material layer. Repeated lifespan of the secondary battery is reduced due to repetition.

On the other hand, even when the number of giant projections (GP) per 5 μm is 9 or more, capacity retention of the secondary battery may be deteriorated due to repetition of charging and discharging. This is because the first and

second surfaces

100a and 100b may not be completely adhered to each other, resulting in an empty space. For this reason, as the number of charge and discharge increases, the amount of the active material detached from the copper foil 100 increases, and the life of the secondary battery is drastically reduced.

Subsequently, the first and second

copper plating layers

121 and 122 are rust-treated by the copper film 110 formed on the mat surface 110a and the shiny surface 110b, respectively. 131 and 132 are formed.

As illustrated in FIG. 3, in the forming of the first and second

protective layers

131 and 132, the first and second

copper plating layers

121 and 122 may be formed. The copper film 110 formed on the mat surface 110a and the shiny surface 110b may be immersed for 2 to 10 seconds in the anticorrosion solution 61 of the antirust treatment tank 60.

The secondary battery electrode (ie, the negative electrode) of the present invention may be manufactured by coating a negative electrode active material on one surface or both surfaces of the secondary battery copper foil 100 manufactured by the above method through a conventional method. A lithium secondary battery can be manufactured using a normal positive electrode, an electrolyte, and a separator together with a secondary battery electrode (cathode).

The lithium secondary battery includes a cathode for providing lithium ions as a cathode during charging, an anode for providing lithium ions as a cathode during discharge, and an electrolyte for providing an environment in which lithium ions can move between the cathode and the cathode. (electrolyte), and a separator that electrically insulates the positive electrode and the negative electrode in order to prevent electrons generated from one electrode from being undesirably consumed by moving to another electrode through the inside of the secondary battery.

In lithium secondary batteries, aluminum foil is used as the positive electrode current collector to be bonded to the positive electrode active material, and copper foil 100 is generally used as the negative electrode current collector to be bonded to the negative electrode active material.

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

As illustrated in FIG. 4, the secondary battery electrode 200 according to the exemplary embodiment of the present invention is a negative electrode of the secondary battery, and the copper foil 100 and the copper foil 100 of any one of the embodiments of the present invention described above. Active material layers 210 and 220 formed on at least one of the first and

second surfaces

100a and 110b.

The active material layers 210 and 220 are carbon; Metals of Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe (Me); An alloy comprising the metal (Me); An oxide of the metal (MeO _x ); And at least one negative electrode active material selected from the group consisting of the metal (Me) and a composite of carbon.

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

* 동박의 제조* Manufacture of Copper Foil

Example 1

A copper film was electrodeposited on the rotary cathode drum by energizing the positive electrode plates and the rotary cathode drum spaced apart from each other by 10 mm in the electrolyte contained in the electrolytic cell at a current density of 50 A / dm ² . For such electroplating, copper wire heat-treated at 700 ° C. was pickled with sulfuric acid and then charged into the electrolyte, and the surface of the rotary cathode drum was polished with a polishing brush having a grain size (Grit) of # 1000.

During the formation of the copper film, the electrolyte was maintained at 50 ° C., continuous filtration of the electrolyte was performed, the flow rate of the electrolyte supplied to the electrolytic cell was 40 m ³ / hour, and the flow rate variation was adjusted to within 1%. In the electrolyte solution, the copper concentration was maintained at 70 ± 10 g / L, the sulfuric acid concentration was maintained at 80 ± 10 g / L, the concentration of thiourea, an organic sulfide-based additive, was maintained at 2 ppm, and the chlorine concentration was It was kept at 10 ppm.

Subsequently, the copper film was passed through two nucleation plating baths, two nuclear growth plating baths, and an antirust treatment tank sequentially to complete a copper foil having a thickness of 24 μm.

In this case, the total current (i _{c_total} ) applied through the nucleation plating baths was 2500 A, and the total current applied through the nuclear growth plating baths for the total current (i _{c_total} ) applied through the nucleation plating baths. The ratio of current i _{t_total} was 0.23.

Example 2

The copper foil with and has the same procedures as in Example 1, except that it was a ratio of 0.31 of the total current (i _{t_total)} is applied through the nuclear growth plating bath for the nucleation bath of a total current (i _{c_total)} applied through Completed.

Example 3

The copper foil with and has the same procedures as in Example 1, except that it was a ratio of 1.97 of the total current (i _{t_total)} is applied through the nuclear growth plating bath for the nucleation bath of a total current (i _{c_total)} applied through Completed.

Comparative Example 1

Copper foil was completed in the same manner as in Example 1, except that the copper film was rust-treated in the rust-preventing bath immediately without passing through the nucleation plating baths and the nuclear growth plating baths.

Comparative Example 2

The copper foil with and has the same procedures as in Example 1, except that it was a ratio of 0.17 of the total current (i _{t_total)} is applied through the nuclear growth plating bath for the nucleation bath of a total current (i _{c_total)} applied through Completed.

Comparative Example 3

The copper foil with and has the same procedures as in Example 1, except that it was a ratio of 2.15 of the total current (i _{t_total)} is applied through the nuclear growth plating bath for the nucleation bath of a total current (i _{c_total)} applied through Completed.

The number of large protrusions, ten-point average roughness (R _zJIS ), room temperature tensile strength, high temperature tensile strength, and elongation of each of the first and second surfaces of the copper foils of the examples and the comparative examples manufactured as described above were obtained by the following methods, respectively. It measured and the result is shown in Table 1.

* 10-point average roughness (R _zJIS )

According to JIS B 0601-1994 "Definition and Display of Surface Roughness", the first surface of copper foil (surface adjacent to the mat surface of copper film) and the second surface on the other side (shiny of copper film) using a contact surface roughness measuring instrument. Ten point average roughness (R _zJIS ) of the plane adjacent to the plane was measured, respectively.

* Giant protrusion count

Observation of an EBSD photograph of the cross section of the sample revealed a large projection per 5 μm of each of the first and second faces of the copper foil (valleys and pores formed on or near the first or second face of the copper film). The number of points passing through the most spaced from the first or second surface and protruding more than 0.7㎛ from the reference line horizontal to the first or second surface).

* Room temperature tensile strength and high temperature tensile strength

At room temperature, the tensile strength of the copper foil was measured using a universal testing machine (UTM) by the method specified in the IPC-TM-650 Test Method Manual. Subsequently, the copper foil was heat-treated at 135 ° C. for 10 minutes, and the tensile strength of the heat-treated copper foil was measured by the same method.

		실시예1Example 1	실시예2Example 2	실시예3Example 3	비교예1Comparative Example 1	비교예2Comparative Example 2	비교예3Comparative Example 3
구리 돌기층 형성 여부Copper Protrusion Layer Formation		○○	○○	○○	××	○○	○○
i_{c_total} i _{c_total}		25002500	25002500	25002500	25002500	25002500	25002500
i_{c_total}/i_{g_total} i _{c_total} / i _{g_total}		0.230.23	0.310.31	1.971.97	--	0.170.17	2.152.15
R_zJIS (㎛)R _zJIS (μm)	제1면Front page	0.220.22	0.290.29	0.780.78	0.180.18	0.220.22	0.770.77
R_zJIS (㎛)R _zJIS (μm)	제2면The second page	0.230.23	0.230.23	0.750.75	0.220.22	0.230.23	0.780.78
거대 돌기 개수Giant protrusion count	제1면Front page	1One	88	88	00	00	99
거대 돌기 개수Giant protrusion count	제2면The second page	55	33	77	00	00	33
상온인장강도 (kgf/mm²)Tensile Tensile Strength (kgf / mm ² )		45.245.2	64.364.3	28.828.8	45.345.3	27.527.5	29.529.5
고온인장강도 (kgf/mm²)High temperature tensile strength (kgf / mm ² )		39.339.3	43.243.2	25.725.7	39.339.3	24.324.3	24.224.2

From Table 1 above, a copper protrusion layer is not formed (Comparative Example 1), or the total current i _{t_total} applied through the nuclear growth plating baths relative to the total current i _{c_total} applied through the nucleation plating baths. When the ratio is less than 0.2 (Comparative Example 2), it can be seen that no large projections are formed on the surface of the copper foil, and are applied through the nuclear growth plating baths for the total current i _{c_total} applied through the nucleation plating baths. When the ratio of the total current i _{t_total} exceeds 2 (Comparative Example 3), it can be seen that more than eight large projections are formed on the surface of the copper foil.

* 이차전지의 제조* Manufacture of secondary battery

Examples 4-6 and Comparative Examples 4-6

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 carbon commercially available for the negative electrode active material, and a slurry was prepared using distilled water as a solvent. On the copper foils of Examples 1 to 3 and Comparative Examples 1 to 3 having a width of 10 cm, the slurry was applied to a thickness of 50 μm using a doctor blade, respectively, and dried at 120 ° C., followed by 1 ton / cm ² of A total of six secondary batteries were prepared by pressing with pressure.

A total of six secondary batteries were manufactured by using an electrolyte, a secondary battery positive electrode, and a separator (porous polyethylene film) together with the anodes for secondary batteries prepared as described above. The electrolyte solution and the positive electrode were prepared as follows.

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

In addition, the 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 90: 10 (weight ratio) . A slurry was prepared by mixing the positive electrode active material and carbon black with polyvinylidene fluoride (PVDF) as a binder and NMP as an organic solvent at 85: 10: 5 (weight ratio). The slurry was applied to both sides of an aluminum foil having a thickness of 20 μm and then dried to prepare a positive electrode.

Discharge capacity retention rates of the secondary batteries of Examples 4 to 6 and Comparative Examples 4 to 6 prepared as described above were measured by the following method, and the results are shown in Table 2 below.

* Discharge capacity retention rate of secondary battery

The capacity per gram of the positive electrode was measured at 4.3 V charging and 3.4 V discharging operating voltage, and 50 charge / discharge experiments were performed at a current density of 0.2 C at a high temperature of 50 ° C. to evaluate the high temperature life. The discharge capacity retention rate was calculated according to Equation 1 below.

Equation 1: Discharge Capacity Retention Rate (%) = (50th Discharge Capacity / 1st Discharge Capacity) × 100

For reference, the discharge capacity retention rate of the secondary battery required in the industry is 90% or more.

		실시예4Example 4	실시예5Example 5	실시예6Example 6	비교예4Comparative Example 4	비교예5Comparative Example 5	비교예6Comparative Example 6
R_zJIS (㎛)R _zJIS (μm)	제1면Front page	0.220.22	0.290.29	0.780.78	0.180.18	0.220.22	0.770.77
R_zJIS (㎛)R _zJIS (μm)	제2면The second page	0.230.23	0.230.23	0.750.75	0.220.22	0.230.23	0.780.78
거대 돌기 개수Giant protrusion count	제1면Front page	1One	88	88	00	00	99
거대 돌기 개수Giant protrusion count	제2면The second page	55	33	77	00	00	33
방전용량 유지율 (%)Discharge Capacity Retention Rate (%)		92.592.5	96.296.2	93.593.5	88.588.5	85.285.2	88.788.7

From Table 2 above, when any one of the first and second faces of the copper foil does not have 1 to 8 huge protrusions (Comparative Examples 4 to 6), the discharge capacity retention rate of the secondary battery made of such copper foil is required by the industry. It can be seen that it does not satisfy the above 90%.

Claims

In the copper foil 100 for secondary batteries which has a 1st surface and the 2nd surface of the opposite side,

A copper film having a mat surface facing the first surface and a shiny surface facing the second surface;

A first copper protrusion layer on the mat surface of the copper film;

A first protective layer on the first copper protrusion layer;

A second copper protrusion layer on the shiny surface of the copper film; And

A second protective layer on the second copper protrusion layer,

When the cross section of the copper foil for secondary batteries is observed with an Electron Backscattered Diffraction (EBSD) photograph, each of the first and second surfaces has 1 to 8 giant protuberances per 5 μm, wherein The giant protrusion passes through the first or second side of the valleys and pores formed at or near the first or second face, the most spaced apart from the first or second face. Projection protruding more than 0.7㎛ from the surface and horizontal reference line

Copper foil for secondary battery.
The method of claim 1,

Each of the first and second surfaces has a ten-point mean roughness (R zJIS ) of 0.2 to 0.8 μm,

Copper foil for secondary battery.
The method of claim 1,

The secondary battery copper foil, characterized in that having a thickness of 4 to 35 ㎛,

Copper foil for secondary battery.
The method of claim 1,

The secondary battery copper foil has a room temperature tensile strength of 28 to 65 kgf / mm 2 and a high temperature tensile strength of 25 kgf / mm 2 or more-the high temperature tensile strength is measured after heat treatment at 135 ℃ for 10 minutes Strength-,

Copper foil for secondary battery.
The method of claim 1,

Each of the first and second protective layers may include at least one of chromium, a nitrogen compound, and a silane compound.

Copper foil for secondary battery.
Manufacturing a copper film having a mat surface and a shiny surface;

Forming a first copper projection layer and a second copper projection layer on the mat surface and the shiny surface of the copper film, respectively; And

Forming a first protective layer and a second protective layer on the first copper protrusion layer and the second copper protrusion layer, respectively,

Forming the first and second copper protruding layers is performed by sequentially passing the copper film through two or more nucleation plating baths and two or more nuclear growth plating baths,

The ratio of the total current applied through the nuclear growth plating baths to the total current applied through the nucleation plating baths is 0.2 to 2,

Manufacturing method of copper foil for secondary batteries.
The method of claim 6,

The manufacturing of the copper film is performed by energizing a positive electrode plate and a rotating cathode drum which are spaced apart from each other in an electrolyte solution,

The electrolyte solution is characterized in that it comprises 50 to 100 g / L copper ions, 50 to 150 g / L sulfuric acid, 50 ppm or less chlorine ions, and an organic additive,

Manufacturing method of copper foil for secondary batteries.
The method of claim 7, wherein

The organic additive is characterized in that the hydroethyl cellulose (HEC), organic sulfide, organic nitride, or a mixture of two or more thereof,

Manufacturing method of copper foil for secondary batteries.
The method of claim 7, wherein

The surface of the rotary cathode drum is characterized in that the polishing brush having a particle size (Grit) of # 800 to # 1500,

Manufacturing method of copper foil for secondary batteries.
The method of claim 7, wherein

The step of manufacturing the copper film,

Heat-treating the copper wire at 600 to 800 ° C;

Pickling the heat treated copper wire;

Injecting the pickled copper wire into the electrolyte solution;

Performing electroplating by energizing the positive electrode plate and the rotary cathode drum while the pickled copper wire is present in the electrolyte; And

Characterized in that it comprises the step of performing continuous filtration of the electrolyte while the electroplating is performed,

Manufacturing method of copper foil for secondary batteries.
The method of claim 10,

Characterized in that the concentration of organic impurities and metal impurities in the electrolytic solution is maintained at 1 g / L or less and 3 g / L or less during the electroplating,

Manufacturing method of copper foil for secondary batteries.
The method of claim 6,

The first and second protective layers are formed by anticorrosion treatment using at least one of chromate, benzotriazole (BTA), and a silane compound. ,

Manufacturing method of copper foil for secondary batteries.
A copper foil having a first face and a second face opposite thereto; And

An active material layer on at least one of the first and second surfaces of the copper foil,

The copper foil,

A copper film having a mat surface facing the first surface and a shiny surface facing the second surface;

A first copper protrusion layer on the mat surface of the copper film;

A first protective layer on the first copper protrusion layer;

A second copper protrusion layer on the shiny surface of the copper film; And

A second protective layer on the second copper protrusion layer,

When the cross section of the copper foil is observed in an EBSD photograph, each of the first and second surfaces has 1 to 8 huge protrusions per 5 μm, wherein the giant protrusions are the first or second surface. Protruding at least 0.7 μm from a baseline horizontally away from the first or second face of the points on the valleys and pores formed at or near the first or second face; Protrusion-,

electrode.
The method of claim 13,

The active material layer is carbon; Metals of Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe (Me); An alloy comprising the metal (Me); An oxide of the metal (MeO x ); And at least one negative electrode active material selected from the group consisting of a complex of metal (Me) and carbon.

electrode.
A cathode;

An anode;

An electrolyte providing an environment in which lithium ions may move between the positive electrode and the negative electrode; And

A separator that electrically insulates the positive electrode and the negative electrode,

The negative electrode,

A copper foil having a first face and a second face opposite thereto; And

An active material layer on at least one of said first and second surfaces of said copper foil,

The copper foil,

A copper film having a mat surface facing the first surface and a shiny surface facing the second surface;

A first copper protrusion layer on the mat surface of the copper film;

A first protective layer on the first copper protrusion layer;

A second copper protrusion layer on the shiny surface of the copper film; And

A second protective layer on the second copper protrusion layer,

When the cross section of the copper foil is observed in an EBSD photograph, each of the first and second surfaces has 1 to 8 huge protrusions per 5 μm, wherein the giant protrusions are the first or second surface. Protruding at least 0.7 μm from a baseline horizontally away from the first or second face of the points on the valleys and pores formed at or near the first or second face; Protrusion-,

Secondary battery.