KR101385761B1 - Electrodeposited copper foil and process for production thereof - Google Patents

Abstract

It is an object of the present invention to provide an electrolytic copper foil that exhibits various stable properties even if the chlorine content fluctuates. And in order to achieve this objective, it is an electrolytic copper foil obtained by electrolyzing a copper electrolyte solution, Comprising: The iodine content in electrolytic copper foil is 0.003 mass% or more, More preferably, it is the range of 0.003 mass%-0.03 mass%. We adopt electrolytic copper foil characterized by. Moreover, it is preferable that the chlorine content of the said electrolytic copper foil is 0.0018 mass% or less.

Description

Electrolytic copper foil and its manufacturing method {ELECTRODEPOSITED COPPER FOIL AND PROCESS FOR PRODUCTION THEREOF}

This invention relates to the electrolytic copper foil and the manufacturing method of an electrolytic copper foil. In particular, it is related with the electrolytic copper foil which has physical characteristics, such as tensile strength and elongation suitable for the electrical power collector uses for lithium ion secondary batteries, and can also be used for copper foil laminated board manufacture for printed wiring board manufacture.

BACKGROUND ART Lithium ion secondary batteries have recently been supplied as useful power sources that can be used repeatedly as environmental awareness and the demand for recycling of resources increase. For example, notebook computers, mobile phones, televisions, It is used for products, such as a video camera. With the miniaturization of these electrical products and electronic devices, a lithium ion secondary battery serving as a power supply source is required to exhibit a small size, high lifespan, and a high energy density.

Looking back at the history of lithium ion secondary battery development, it has been tried to use the rolled copper foil which was excellent in surface smoothness for the negative electrode collector which comprises the negative electrode of a lithium ion secondary battery. At present, either a rolled copper foil or an electrolytic copper foil is used for the negative electrode collector which comprises the negative electrode of a lithium ion secondary battery.

In the manufacturing process of the negative electrode of a lithium ion secondary battery, as disclosed in patent document 1 or patent document 2, there exists a process of applying high temperature. In this process, high temperature is imposed also on the copper foil which is a negative electrode collector which comprises a negative electrode. As a result, when the said copper foil softens, there exists a problem that it becomes easy to be influenced by the deformation stress accompanying expansion-contraction of the negative electrode active material when a lithium ion secondary battery repeats charging / discharging.

In connection with this problem, in the case of a rolled copper foil obtained using relatively inexpensive tough pitch copper, recrystallization by heating easily occurs and softens, so the effect of expansion and contraction stress when repeating the above-described charge and discharge is affected. It was easy to receive, and it was difficult to prolong the life of a lithium ion secondary battery. Moreover, rolled copper foil originates in the manufacturing method, is expensive, and it is difficult to provide it at a lower price than electrolytic copper foil. This has been an obstacle to operators in overcoming global price competition. Moreover, since rolled copper foil is difficult to widen as copper foil, it is difficult to improve the production efficiency in battery manufacture, and there exists a limit to reduction of product cost, and it becomes an unavoidable fault.

On the other hand, since electrolytic copper foil is hard to recrystallize by heating and it is hard to soften, it has been considered that the resistance to expansion-shrinkage stress at the time of repeating charge-discharge mentioned above is strong. Moreover, since an electrolytic copper foil is cheap compared with a rolled copper foil, the profitability which could be seen from the price point of the lithium ion secondary battery in the market can be improved, and the use of an electrolytic copper foil as an alternative product of a rolled copper foil has been actively examined. As a result, the electrolytic copper foil which has both low profile surfaces of the level of a rolled copper foil is used widely now as a negative electrode collector of a lithium ion secondary battery.

Production of an electrolytic copper foil as a technique regarding the electrolytic copper foil on which both surfaces have the low profile surface of the rolled copper foil level, as disclosed in patent document 3, patent document 4, etc. in order to lower the surface roughness of the precipitation surface of an electrolytic copper foil. There is an invention in which an electrolyte composition, an electrolyte temperature, a current density, and the like of the copper electrolyte solution to be used are controlled.

In Patent Document 3, for the purpose of producing an electrodeposited copper foil excellent in etching properties and impedance controllability, which is useful for the manufacture of a printed circuit board, '(A) an electrolyte solution is flowed between the anode and the cathode, and copper is deposited on the cathode. Applying an effective positive voltage between the anode and the cathode as much as possible; Wherein the electrolytic solution comprises copper ions, sulfate ions and at least one organic additive or derivative thereof, the concentration of chlorine ions being up to about 1 ppm; The current density ranges from about 0.1 to about 5 A / cm 2; (B) including a step of removing copper foil from the cathode '. That is, the electrolytic conditions using the copper electrolyte which controlled the chlorine concentration are employ | adopted.

And in patent document 4, 0.05-2.0 weight ppm thiourea or its derivative (s) as an additive; 0.08-12 ppm by weight of a polymer polysaccharide; And an electrolyte solution containing an electrolyte solution containing 0.03 to 4.0 wtppm of glue having a molecular weight of 10,000 or less. As a result, it is said that the electrolytic copper foil which made the surface roughness of the precipitation surface of the said electrolytic copper foil close to the surface roughness level of a rolled copper foil can be manufactured.

In addition, in Patent Document 5, the electrolytic copper foils described in Patent Documents 3 and 4, which have reduced surface roughness by miniaturizing the crystal structure, sufficiently satisfy the market demand in terms of charge and discharge cycle life and overcharge characteristics. It is pointed out that this is not a situation. Patent Document 5 describes the characteristics of copper foil that affects charge and discharge cycle life and overcharge characteristics, such as surface smoothness, normal temperature tensile strength, elongation, non-recrystallization, and high temperature, which cannot be represented by 10-point average roughness Rz. It was found that the elongation in the atmosphere was important and succeeded in obtaining the copper foil having the highest effect in the secondary battery characteristics. Example 1 of Patent Document 5 '280 g / L copper sulfate pentahydrate, 100 g / L sulfuric acid, and chlorine ion 35 7 ppm of low molecular weight gelatin having an average molecular weight of 3000, 3 ppm of hydroxyethyl cellulose, and 1 ppm of 3-mercapto-1-propanesulfonate were added to an acidic copper sulfate sulfate solution containing ppm, and the electrolyte temperature was 55 ° C. and the flow rate was 0.3 m. Per minute, current density of 50 A / dm 2, and the like, wherein the surface roughness of the electrodeposited surface of the electrolytic copper foil is 10 micrometers with a ten point average roughness Rz. While being fixed, the minimum peak-to-peak distance between the bases is 5 µm or more, the room temperature tensile strength is 40 kg / mm 2 or less, and the deterioration of the room temperature tensile strength after heat treatment at 130 ° C. for 15 hours is within 15%. The electrolytic copper foil 'which is not formed is disclosed.

Patent Document 1: Japanese Patent Application Laid-Open No. 2006-236684 Patent Document 2: Japanese Patent Application Laid-Open No. 2008-282550 Patent Document 3: Japanese Patent Application Laid-Open No. 7-188969 Patent Document 4: Japanese Patent Application Laid-Open No. 8-53789 Patent Document 5: Japanese Patent Application Laid-Open No. 2004-79523

However, although the electrolytic copper foil used for the negative electrode electrical power collector of a lithium ion secondary battery, it is always required to improve the characteristic of copper foil which affects charge / discharge cycle life and overcharge characteristics, as the said patent document 5 points out. And the dispersion | variation in physical characteristics, such as elongation and tensile strength of an electrolytic copper foil, might become a problem.

As a result of tracking this factor, it was thought that the cause was chlorine contained in the copper electrolyte solution used for manufacture of an electrolytic copper foil. Chlorine may be added and controlled intentionally, or may be mixed as an unavoidable impurity through a vinyl chloride pipe. And from an electrochemical point of view, chlorine in the electrolyte is a component that tends to affect product quality even if there is a small amount of variation. Therefore, although the person skilled in the art has improved the manufacturing method for the purpose of reducing the variation of the original quality of the electrolytic copper foil with respect to the electrolytic copper foil manufactured electrochemically, the fluctuation of the chlorine concentration was considered an inevitable factor.

On the other hand, the electrolytic copper foil used for the electrical power collector for lithium ion secondary batteries has requested | required further stabilization of the quality, and it is heat softening resistance and bending resistance which do not soften easily even if it heats more than what has been accepted with the conventional electrolytic copper foil. In fact, stabilization of the quality at a high level such as the current collector bending performance in the state of a 'negative current collector with negative electrode active material (negative electrode)' carrying a negative electrode active material is required.

Therefore, the present inventors came to invent the electrolytic copper foil mentioned later as an electrolytic copper foil suitable for the constituent material of the electrical power collector for lithium ion secondary batteries, and the copper foil laminated board use for printed wiring board manufacture, as a result of earnestly researching. Moreover, by employ | adopting the manufacturing method mentioned later, efficient production of the electrolytic copper foil which concerns on this invention was enabled.

Electrolytic copper foil which concerns on this invention: The electrolytic copper foil which concerns on this invention is an electrolytic copper foil obtained by electrolytic copper electrolyte, It is characterized by the iodine content in electrolytic copper foil being 0.003 mass% or more.

Surface-treated copper foil which concerns on this invention: The surface-treated copper foil which concerns on this invention was surface-treated to the surface of the electrolytic copper foil containing the iodine mentioned above.

The manufacturing method of the electrolytic copper foil which concerns on this invention: The manufacturing method of the electrolytic copper foil which concerns on this invention is a manufacturing method of the electrolytic copper foil containing the above-mentioned iodine, The iodine density | concentration as copper electrolyte solution is 1.5 mg / L-15.0 mg / L range. A sulfuric acid acid copper sulfate electrolyte solution is used. The copper electrolyte more preferably has a chlorine concentration of 1.0 mg / L or less.

And in the manufacturing method of the electrolytic copper foil which concerns on this invention, it is preferable to electrolyze the temperature of copper electrolyte solution at the electrolysis conditions of 40 degreeC-60 degreeC, and current density of 50 A / dm <2> -85 A / dm <2>.

The negative electrode for lithium ion secondary batteries obtained using the surface-treated copper foil which concerns on this invention: The negative electrode for lithium ion secondary batteries which concerns on this invention used the surface-treated copper foil which concerns on this invention mentioned above as a negative electrode electrical power collector.

The electrolytic copper foil which concerns on this invention contains 0.003 mass% or more of iodine as mentioned above. Thus, by containing iodine in the bulk copper of an electrolytic copper foil, even if the chlorine content in an electrolytic copper foil fluctuates, it will exhibit stable physical characteristics.

Therefore, by using the electrolytic copper foil which concerns on this invention for the negative electrode of a lithium ion secondary battery, it is excellent in the resistance to the expansion-shrinkage behavior which accompanies charging and discharging, and can provide a long life lithium ion secondary battery on a market cheaply.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure for considering the relationship between the "electrolytic copper foil physical property" and the "iodine content and chlorine content which an electrolytic copper foil contains."

Hereinafter, it demonstrates in detail in order of the electrolytic copper foil which concerns on this invention, the manufacturing method of a surface-treated copper foil, and the negative electrode for lithium ion secondary batteries obtained using the said surface-treated copper foil.

Form of the electrolytic copper foil which concerns on this invention: The electrolytic copper foil which concerns on this invention is an electrolytic copper foil obtained by electrolyzing a copper electrolyte solution. This electrolytic copper foil is characterized by the iodine content in electrolytic copper foil being 0.003 mass% or more. Thus, the electrolytic copper foil containing iodine is suitable as an electrical power collector for lithium ion secondary batteries, and is an electrical power collector in the "current collector with a negative electrode active material (negative electrode)" state which carried the heat-softening resistance, bending resistance, and the negative electrode active material actually. Improve bending performance at the same time.

Here, it is preferable that the iodine content in electrolytic copper foil is 0.003 mass% or more. When the said iodine content is less than 0.003 mass%, stability is insufficient in all the characteristics, and it becomes difficult to stabilize product quality. On the other hand, when iodine content in an electrolytic copper foil becomes 0.003 mass% or more, since it shows stable physical characteristics even if chlorine content in an electrolytic copper foil fluctuates, it is preferable. Strictly speaking, however, if the iodine content exceeds 0.03 mass%, none of the above-described properties will be improved further, but rather, embrittlement of the electrolytic copper foil will result, leading to deterioration of the bending characteristics, and Since the fall of appearance quality also tends to be remarkable, it is preferable to make iodine content into 0.03 mass% or less.

In addition, in the case of the electrolytic copper foil which concerns on this application, in addition to the iodine mentioned above, it is preferable to control chlorine content in an electrolytic copper foil. That is, in the case of the electrolytic copper foil which concerns on this invention, it is preferable that chlorine content measured by the chemical analysis method is 0.0000 mass%-0.0018 mass%. That is, when the chlorine content contained in an electrolytic copper foil is 0.0018 mass% or less, since the surface roughness of a precipitation surface becomes low and it is easy to obtain a low profile precipitation surface, it is preferable as a constituent material of the electrical power collector for lithium ion secondary batteries. In addition, although it demonstrates in detail in the part which compares an Example and a comparative example, in order to improve the heat softening resistance at the time of high temperature heating, it is preferable that the said chlorine content is 0.0006 mass%-0.0018 mass%.

And the electrolytic copper foil which concerns on this invention is chlorine content and iodine content measured by the chemical analysis method, and the relationship of following formula (1) (chlorine content and iodine content of the electrolytic copper foil suitable for the negative electrode electrical power collector use of a lithium ion secondary battery). It is desirable to satisfy the relationship). By satisfying such a relationship, even when heated to the temperature of about 350 degreeC, it shows very high heat softening resistance. This point will be described in detail in the following Examples. Hereinafter, the analysis method of chlorine content and iodine content is demonstrated.

Chlorine content was measured as follows. After copper foil is heated and dissolved in nitric acid, a certain amount of silver nitrate solution is added thereto. Next, a fixed amount of KBr solution is added to coprecipitate chloride ions with silver bromide. Allow to stand for 15 minutes in the dark, then filter and wash the precipitate. The precipitate is then transferred to a beaker, where the precipitate is dissolved in thiourea solution and left overnight in the dark. Dilute this solution to a certain volume, measure the chloride ion concentration on an ion chromatograph (ICS-2000 from Dionex, electrical conductivity detector, KOH for eluent, AS-20 for column) and measure the chloride ion concentration. Calculated.

Iodine content was measured as follows. The copper foil was oxidized, melted and cooled while warming in aqua regia, and then cooled to a constant volume, and the intensity of I: 178 nm (Ar purge) was obtained in ICP-AES (Seiko Instruments Inc. product SPS3000). It measured and computed iodine content.

Moreover, the electrolytic copper foil which concerns on this invention has a component characteristic that the main impurity content of each component sum total of carbon, oxygen, sulfur, and nitrogen is 0.01 mass% or less as a result of measuring this by the gas analysis method. It is not clear what kind of action these main impurity contents have in the electrolytic copper foil used for the negative electrode electrical power collector of a lithium ion secondary battery at this stage. However, the main impurity component mentioned here is an element which is easy to segregate in the grain boundary, and when the main impurity content is 0.01% by mass or less, the toughness of the electrolytic copper foil is improved, resulting in a good balance between elongation and tensile strength.

In addition, the present inventors measured the copper purity for the electrolytic copper foil which concerns on this invention using the glow discharge mass spectrometer. As a result, the copper purity obtained using the glow discharge mass spectrometer was a high purity value of 99.99 mass% or more. Obviously, considering the iodine content and chlorine content measured using the above-described chemical analysis method, and the main impurity content of each component sum of carbon, oxygen, sulfur and nitrogen measured by the gas analysis method, this glow discharge mass spectrometer was obtained. The purity is not a consistent value, but you can think of it as an error from different analytical methods.

Next, the physical characteristic which the electrolytic copper foil which concerns on this invention has is demonstrated. In addition, in describing the said physical characteristic, it assumes the case where the bulk thickness of an electrolytic copper foil is 18 micrometers ± 1.8 micrometers, and demonstrates.

The surface roughness of the precipitation surface of the electrolytic copper foil which concerns on this invention is demonstrated. The surface roughness of the precipitation surface of the electrolytic copper foil which concerns on this invention can understand that a value of Rzjis is a precipitation surface of low profile in the range of 0.70 micrometer-2.0 micrometers. Here, when the value of Rzjis exceeds 2.0 micrometers, it becomes difficult to carry | support a negative electrode active material uniformly at the time of manufacturing the negative electrode for lithium ion secondary batteries. In addition, repeated charging and discharging is not preferable because the tendency for lithium to easily grow in a dendrite shape on the convex portions of the current collector surface becomes stronger. On the other hand, when the value of Rzjis is less than 0.7 micrometer, since a surface state is too smooth and when using as a negative electrode collector of a lithium ion secondary battery, adhesiveness between a negative electrode active material and a negative electrode collector falls, it is unpreferable. Moreover, in order to stabilize the characteristic as a lithium ion secondary battery, it is preferable that the difference of the Rzjis value of both surfaces of an electrolytic copper foil is within 0.6 micrometers. In addition, Rzjis (10 point average roughness) here is the value measured with the stylus type surface roughness meter (0.2 micrometer of curvature radius of a stylus tip) based on JISB0601.

The physical characteristic which measured the electrolytic copper foil which concerns on this invention in a normal state is demonstrated. Electrolytic copper foil according to the present invention, it is preferred that the normal value of the elongation (E ₀₎ of 2.0% to 9.0% range. When elongation normally becomes 2.0% or more, it becomes suitable for the negative electrode electrical power collector use of a lithium ion secondary battery. On the other hand, when the elongation is usually 9.0% or less, the deformation resistance due to expansion and contraction during charge and discharge when used for the negative electrode current collector of the lithium ion secondary battery falls within an appropriate range. In addition, in this application, the measurement of this elongation and the measurement of the tensile strength mentioned later are the values measured by performing a tensile test with respect to the electrolytic copper foil sample of 10 mm width.

Then, the electrolytic copper foil according to the invention shows a range of a usual tensile strength (F ₀₎ is 48 kgf / ㎟ to 72 kgf / ㎟ value. When the value of usual tensile strength (F ₀ ) is 48 kgf / mm 2 or more, when used for the negative electrode current collector of a lithium ion secondary battery, there exists a tendency for the deformation resistance with respect to the expansion shrinkage at the time of charge / discharge to become favorable. On the other hand, in the usual case of the tensile strength (F ₀₎ is 72 kgf / ㎟ less value, is in the range of the above-described appropriate usual elongation reliably.

Next, the physical characteristic measured after carrying out constant heat treatment to the electrolytic copper foil which concerns on this invention is demonstrated (Hereinafter, it may only be called "after heating."). The heat treatment here means to heat-process 180 degreeC * 60 minutes to the electrolytic copper foil of a steady state in air | atmosphere atmosphere.

As for the electrolytic copper foil which concerns on this invention, the value of elongation E _a after heating will become 4%-10% of range. The circuit comprised with copper foil in the manufacturing process of a printed wiring board, and the negative electrode electrical power collector manufactured with copper foil in the manufacturing process of the negative electrode of a lithium ion secondary battery are exposed to various high temperature load environments. Therefore, the physical property after heating of this electrolytic copper foil becomes a very important factor which determines product quality. If the value of elongation (E _a ) after heating is 4% or more, it will become an appropriate elongation in the negative electrode electrical power collector use of a lithium ion secondary battery. On the other hand, when the elongation after heating is 10% or less, the deformation resistance due to expansion and contraction during charge and discharge when used for the negative electrode current collector of the lithium ion secondary battery falls within an appropriate range.

And the electrolytic copper foil which concerns on this invention shows the value of 38 kgf / mm <2> -72 kgf / mm <2> of the tensile strength F _a after heating after heat-processing 180 degreeC * 60 minutes. When the value of the tensile strength (F _a ) after heating is 38 kgf / mm 2 or more, it is difficult to be affected by the thermal history in the processing process, and when used for the negative electrode current collector of a lithium ion secondary battery, The deformation resistance also tends to be good. On the other hand, when the value of tensile strength F _a after heating is 72 kgf / mm <2> or less, since it becomes easy to maintain the range of the suitable normal elongation mentioned above, it is preferable.

In addition, the value of the tensile strength (F _a) electrolytic copper foil is, after the value and heated by a 180 ℃ × 60 bun heat treatment described above after the one normal tensile strength (F ₀₎ described above as a physical feature according to the present invention, the following It is preferable to satisfy the relationship of equation (2).

Equation 2 means that the difference between 'normal tensile strength (F ₀ )' and 'tensile strength (F _a ) after heating' is small, and thus it is difficult to soften even under constant heating. In the manufacturing process of the negative electrode of a lithium ion secondary battery, copper foil is affected by various thermal history. As a result, when the said copper foil softens, all the deviations of the bending performance required as the negative electrode strength of a lithium ion secondary battery, and the deformation resistance with respect to the expansion and contraction at the time of charge / discharge when used for a negative electrode collector become large, and a lithium ion secondary battery It is not preferable because the quality stability as is not secured. Therefore, a softening resistance to this level of heating is required.

Moreover, it is preferable that the physical characteristic of the electrolytic copper foil which concerns on this invention shows the high bending performance that the frequency | count of bending until reaching a fracture is 3000 or more in the bending resistance test after the heating after 180 degreeC x 60-minute heat processing. . When the number of bendings in the bending resistance test after heating reaches 3,000 or more, the deformation resistance to expansion and contraction during charging and discharging is dramatically improved when used in the negative electrode current collector of a lithium ion secondary battery, thereby prolonging the product life. . The post-heating bending test mentioned here is an important characteristic calculated | required also in the case of the electrolytic copper foil for printed wiring boards. On the other hand, although the upper limit is not clearly described with respect to the number of times of bending, empirically speaking, it is about 6500 times. On the other hand, after the heat-resistant bending test referred to here is the Tester Sangyo Co., Ltd. (TESTER SANGYO) based on the measuring method of JIS C 5016 after heat-processing 10 degreeC x 10 cm rectangular electrolytic copper foil for 180 degreeC * 60 minutes. CO ,. LTD.) Measure the number of bends until the break is reached with a flexible bending tester (bending radius: 1 mm, bending speed: 100 cpm, stroke: 20 mm).

Form of surface-treated copper foil which concerns on this invention: The surface-treated copper foil which concerns on this invention characterized by performing various surface treatment on the surface of the electrolytic copper foil containing the above-mentioned iodine. Surface treatment means performing any 1 type, or 2 or more types of a roughening process, an antirust process, and a silane coupling agent process to the surface of the above-mentioned electrolytic copper foil. This surface treatment is performed on the surface of an electrolytic copper foil for the purpose of providing adhesive strength, chemical-resistance, heat resistance, etc. in consideration of the required characteristic by each use. Moreover, when talking about a silane coupling agent process, in the case of the electrolytic copper foil used for the negative electrode collector of a lithium ion secondary battery, it is preferable to carry out on both surfaces of an electrolytic copper foil, and in the case of the electrolytic copper foil used for a printed wiring board, one side of an electrolytic copper foil It is preferable to carry out.

Manufacture form of the electrolytic copper foil which concerns on this invention: The manufacturing method of the electrolytic copper foil which concerns on this invention is a manufacturing method of the electrolytic copper foil containing iodine mentioned above, It is characterized by the composition of the sulfuric acid type coin dissolution solution used here. On the other hand, the copper concentration in the sulfuric acid-based coin dissolution solution referred to herein uses 50 g / L to 120 g / L, more preferably 50 g / L to 80 g / L. In addition, the free sulfuric acid concentration is considered based on the range of 60 g / L to 250 g / L, more preferably 80 g / L to 150 g / L.

It is preferable that the iodine concentration in the sulfate-based coin solution is in the range of 1.5 mg / L to 15.0 mg / L. More preferably, it is the range of 2.5 mg / L to 7.0 mg / L. When the iodine concentration in the sulfuric acid solution is less than 1.5 mg / L, the amount of iodine contained in the electrolytic copper foil precipitated by electrolysis is insufficient, and the resulting electrolytic copper foil has physical properties such as surface roughness, elongation, tensile strength, etc. in the appropriate range described above. It is not preferable because it cannot be obtained and the change over time of various physical properties also tends to be large. On the other hand, when the said iodine concentration exceeds 15.0 mg / L, the iodine content in electrolytic copper foil will increase and the above-mentioned problem will arise. Moreover, the smoothness of the precipitation surface of electrolytic copper foil and favorable mechanical strength can be made compatible by making the said iodine concentration into 7.0 mg / L or less. At this time, it is preferable to use iodide, such as NaI and KI, for addition of iodine.

Moreover, it is preferable that the chlorine concentration of the copper electrolyte solution used for this invention is 1.0 mg / L or less. When the said chlorine concentration exceeds 1.0 mg / L, since the electrolytic copper foil obtained will become brittle, it is not preferable. And in order to further stabilize the range of the chlorine concentration which the electrolytic copper foil which concerns on this invention contains, it is preferable to exist in the range of 0.4 mg / L-0.8 mg / L. By employing the chlorine concentration in this range, it is possible to balance each component described above, to reduce the precipitation surface, and to enable stable production of high strength electrolytic copper foil. When adjusting the chlorine concentration in this sulfuric acid solution, it is preferable to use hydrochloric acid or copper chloride (II). This is because it does not adversely affect the solution property of the sulfuric acid-based coin solution.

And in the manufacturing method of the electrolytic copper foil which concerns on this invention, it is preferable to electrolyze the temperature of the copper electrolyte solution in 40-60 degreeC and the range of a current density of 50 A / dm <2> -85 A / dm <2>. When solution temperature is less than 40 degreeC, there exists a tendency for the dispersion of physical strength, such as tensile strength and elongation, of the electrolytic copper foil obtained by lack of electrolytic stability to become large. On the other hand, when the solution temperature exceeds 60 ° C, the evaporation of the water in the solution becomes remarkable and the stability of the solution composition is insufficient, which makes the process management cumbersome and undesirable.

Moreover, when the current density at the time of electrolysis here is less than 50 A / dm <2>, it is unpreferable since industrially required production efficiency is not acquired and production efficiency falls. On the other hand, when the current density at the time of electrolysis exceeds 85 A / dm <2>, a dispersion | variation tends to arise in physical characteristics, such as surface roughness and tensile strength of the precipitation surface of the manufactured electrolytic copper foil, and it is unpreferable.

Negative electrode for lithium ion secondary batteries obtained using the surface-treated copper foil which concerns on this invention: The negative electrode for lithium ion secondary batteries obtained using the surface-treated copper foil which concerns on this invention characterized by using the above-mentioned surface treatment copper foil as a negative electrode electrical power collector. Generally, the negative electrode for lithium ion secondary batteries carries out the negative electrode active material on the surface of the surface-treated copper foil which is a negative electrode collector, and is made into the negative electrode collector state with a negative electrode active material. In this manufacturing process, by using the surface-treated copper foil using the electrolytic copper foil which concerns on this invention, it is a house | seat in the state of the "current collector with negative electrode active material (cathode) with favorable heat-softening resistance, bending resistance property, and actually carrying the negative electrode active material." It is possible to improve the overall bending performance at the same time.

Other Application Fields of Electrolytic Copper Foil According to the Present Invention: The electrolytic copper foil and the surface-treated copper foil according to the present invention are exclusively used for the production of a copper foil laminate for production of a printed wiring board (hereinafter, sometimes referred to simply as "copper laminate)." It is also possible. For example, it is also possible to laminate | stack the above-mentioned surface-treated electrolytic copper foil and insulation layer constitution material, and to obtain the copper foil laminated board for printed wiring board manufacture. In addition, although described for the case, the concept of the copper foil laminated board mentioned here includes two rigid copper foil laminated boards and a flexible copper foil laminated board. Since the electrolytic copper foil which concerns on this invention is low profile, it is suitable for formation of the fine-pattern circuit of the level required for the flexible printed wiring board containing TAB, COF, etc.

EMBODIMENT OF THE INVENTION Hereinafter, the Example for easy understanding of the electrolytic copper foil etc. which concerns on this invention is described.

<Examples>

In the present Example, it was adjusted so that it might become each additive density | concentration shown in Table 1 using the basic solution which is copper sulfate solution, copper concentration 80g / L, and free sulfuric acid concentration 140g / L as a sulfuric acid type coin dissolution solution. At this time, iodine was added using potassium iodide (KI), and hydrochloric acid was used to adjust the chlorine concentration. And the electrolytic copper foil containing 8 types of iodine of the sample 1-the sample 8 was manufactured using the sulfuric acid type coin dissolution liquid of the composition from which the additive of Table 1 mix | blended. On the other hand, this Example is for clarifying the difference in general physical properties as copper foil by comparing with a comparative example.

The production of electrolytic copper foil was performed by electroplating a titanium plate electrode whose surface was polished using # 2000 abrasive paper as a cathode, using DSA as the anode, under a solution temperature of 50 ° C. and a current density of 75 A / dm 2, and having a thickness of 18 μm. An electrolytic copper foil containing iodine was produced. The surface roughness (Rzjis) of the glossy surface (opposite surface of a precipitation surface) of these electrolytic copper foil was 1.4 micrometers. The evaluation result of each characteristic of the electrolytic copper foil obtained here is shown together in Table 2 so that a comparison with the following comparative example is possible.

Here, various measurement conditions etc. are demonstrated. The measurement of the steady state, the tensile strength after heating, and the elongation of the sample according to the example was performed in accordance with IPC-TM-650. In addition, measurement of surface roughness was performed based on JISB0601-2001. The same is true for the following comparative examples.

<Comparative Example>

In the comparative example, the comparative sample 1 and the comparative sample 2 used copper electrolyte whose iodine concentration is 0.5 mg / L or less, and are a comparative example used for contrast with the above-mentioned Example. And the comparative sample 3 and the comparative sample 4 use the copper electrolyte solution (copper electrolyte solution containing no iodine) of 0.0 mg / L of iodine concentration. Otherwise, Comparative Samples 1 to 4 were obtained under the same production conditions as in Example. The liquid composition is shown in Table 1 together with the liquid composition of the examples.

[Points to be Seen from the Comparison of Examples and Comparative Examples]

Contrast of basic physical properties as copper foil: An Example and a comparative example are prepared, referring Table 1, Table 2, and drawings.

From Table 1, Samples 1 to 8 according to the examples are in the range of 'chlorine concentration of 1.0 mg / L or less and iodine concentration of 1.5 mg / L to 15.0 mg / L', which are suitable as the copper electrolyte of the present invention. An acid sulfuric acid copper sulfate electrolyte solution is used. On the other hand, Comparative Samples 1 to 4 each contain chlorine and iodine, which are considered suitable because they do not use the sulfuric acid acid copper sulfate electrolyte solution contained in the range of 1.5 mg / L to 15.0 mg / L. It turns out that electrolyte solution is not used.

As Table 2 shows, in the manufacturing method of the electrolytic copper foil containing iodine which concerns on this application, the chlorine concentration of 1.0 mg / L or less and the iodine concentration of 1.5 mg / L-15.0 mg / L of copper electrolyte are By using the sulfuric acid acidic copper sulfate electrolyte solution which satisfy | fills a condition, the electrolytic copper foil of 0.005 mass%-0.063 mass% is obtained. This electrolytic copper foil has a condition where the precipitation surface is smooth and the difference in tensile strength between normal and after heating, that is, the value of [normal tensile strength (F ₀ )]-[tensile strength after heating (F _a )] is 10 kgf / mm 2 or less. It can be seen that to satisfy.

Consideration of characteristics as a negative electrode current collector of a lithium ion secondary battery 1: In this consideration 1, the data in Table 2 described above was `` iodine content in foil '' in the Y direction of the vertical axis in the XY coordinate plane, and `` in the X direction of the horizontal axis ''. Figure 1 shows the concentration of chlorine in the foil. And the data of all the examples are contained in the area | region above the line of 0.003 mass% of iodine content shown in FIG. On the other hand, it turns out that the comparative sample of a comparative example is less than 0.003 mass% of iodine content.

Here, looking back at the description of Table 2, only the iodine content of the electrolytic copper foil of the sample 7 exceeded 0.03 mass% in an Example. As a result, it can be seen that the number of times of bending of the bending resistance test after heating of the sample 7 is 1105 times lower than the number of times of bending of other samples. This supports that when the iodine content in electrolytic copper foil exceeds 0.03 mass%, the structure of electrolytic copper foil tends to embrittle.

And the thing which has the iodine content and chlorine content which fall in the upper area | region of the straight line of FIG. 1 (the area | region shown by Formula 1 mentioned above) for the electrolytic copper foil used for the negative electrode electrical power collector use for lithium ion secondary batteries is used for heating. It is preferable because the resistance against heat softening becomes particularly high, and furthermore, the resistance to heat softening is stabilized. That is, it is thought that it is especially preferable that the electrolytic copper foil used for the negative electrode electrical power collector use for lithium ion secondary batteries considers not only the iodine content in electrolytic copper foil but also the chlorine content in electrolytic copper foil, and satisfy | fills the relationship shown by Formula (1).

In view of the above comprehensively, in the case of the electrolytic copper foil containing iodine according to the present application, the iodine content is 0.003% by mass to 0.03% by mass, while the chlorine content is 0.0006% by mass to 0.0018% by mass, It can be judged that it exists in the range which satisfy | fills the most preferable characteristic as a negative electrode electrical power collector of a lithium ion secondary battery.

Consideration of Characteristics as a Negative Current Collector of a Lithium Ion Secondary Battery 2: Discussion 2 is for explaining the heat softening resistance peculiar to an electrolytic copper foil containing iodine according to the present invention. The relationship between the tensile strength after heating after performing. That is, in consideration of the high temperature atmosphere imposed in the manufacturing process of the negative electrode of a lithium ion secondary battery, it is for contrasting the change of the physical characteristic after heating at 350 degreeC with a comparative example. In the discussion 2, for convenience of explanation, the samples extracted from the samples 1 to 8 and the comparative samples 1 to 4 used in the comparative example will be described.

Table 3 shows the relationship between the 'normal tensile strength (F ₀ )' and 'the tensile strength (F _b ) after heating after heating at 350 ° C.'. Here, after heating 350 degreeC x 60 minutes with respect to copper foil, it is the result of having performed the tension test using the rectangular sample of length 10cm x width 10mm.

Also in Table 3, even if the electrolytic copper foil containing iodine contained sample 3 which does not contain chlorine, the tensile strength falls very largely after 350 degreeC x 60 minutes of heat processing. In addition, in the case of the comparative sample 1, the comparative sample 2, and the comparative sample 4, although the tensile strength after heating showed the value below 30 kgf / mm <2>, the samples 1 to 3 hold | maintained 30 kgf / mm <2> or more. In contrast, while the sample 2 is in a region that satisfies the relationship shown in Equation 1 described above, and is subjected to heat treatment at 350 ° C. for 60 minutes in the hatching region of FIG. 1, the sample 2 has a high tensile strength of 40 kgf / mm 2 or more. And the number of bending of the bending resistance test shown in Table 2 also shows an excellent value.

On the other hand, it is 350 degreeC * by the range (the formula shown in Formula (1) mentioned above) divided by the straight line A of FIG. 1 which showed the "relationship between the iodine content and chlorine content in the electrolytic copper foil physical property after a heating process" demonstrated in the consideration 1. We know that the physical property of the electrolytic copper foil which concerns on this application after 60 minutes of heat processing is distinguished.

That is, what has iodine content and chlorine content which enter the upper area | region (the area | region which satisfy | fills the conditions shown by Formula 1) of the straight line of FIG. 1 is a characteristic calculated | required as an electrolytic copper foil used for the negative electrode electrical power collector uses for lithium ion secondary batteries. It is preferable because the heat-softening resistance to heating is particularly high, and furthermore, the heat-softening resistance is stable. Therefore, it is clear that it is especially preferable that the electrolytic copper foil used for the negative electrode collector use for lithium ion secondary batteries considers not only the iodine content in electrolytic copper foil but also the chlorine content in electrolytic copper foil, and satisfy | fills the relationship shown by Formula (1) mentioned above. .

From the above, it can be understood that the electrolytic copper foil needs to contain iodine and chlorine in a balanced manner. It is understood that the electrolytic copper foils of Samples 1 and 2, which are classified as such electrolytic copper foils, have a high softening resistance due to heating, and exhibit sufficient deformation resistance against expansion and contraction behavior during charging and discharging even when used for the production of a negative electrode of a lithium ion secondary battery. Can be.

Consideration of characteristics as a negative electrode current collector of a lithium ion secondary battery 3: Discussion 3 Also for explaining the thermal softening resistance peculiar to an electrolytic copper foil containing iodine according to the present invention, the 'heat-resistant bending tensile test results' will be described. . The heat-resistant bending tensile test (special method) is a result of the tensile test after heat-processing 350 degreeC x 60 minutes with respect to copper foil. This result is described in Table 4. The test method of the heat resistant bending tension test (special method) here is as follows.

(Heat-resistant bending tensile test sequence)

1. A 1 cm x 10 cm rectangular copper foil sample for tensile tests is heat-processed for 60 minutes at predetermined | prescribed heating temperature (heating temperature 350 degreeC of special method, other 180 degreeC) in air | atmosphere, and is cooled.

2. Then, the sample is bent and subjected to 180 ° bending stress for 1 minute while a 15 kg load is applied thereto to form a bent portion, and the original rectangle is returned.

3. Tensile strength and elongation are measured in a tensile tester in a room temperature atmosphere.

4. Evaluation item

Heat-resistant tensile strength (without (2) in the heat-resistant bending tensile test sequence)

Heat-resistant bending tensile strength

Here, the reason why the above-described heat-resistant bending tensile test (special method) is adopted will be described. When a lithium ion secondary battery forms an active material layer in the electrical power collector for negative electrodes which used copper foil, high temperature is imposed. In the case of a square lithium ion secondary battery, a negative electrode having a high temperature applied thereto to form an active material layer is provided with a step of bending and flattening a square in a steady state laminated with a positive electrode or a separator. Therefore, the heat resistant bending tensile test (special method) is introduced to evaluate the resistance of the copper foil to the load when such bending processing is performed.

From Table 4, it turns out that an Example (sample 1, the sample 2, the sample 5, the sample 6) is relatively high also in the bending tensile strength after 180 degreeC x 60-minute heating compared with the comparative sample 1. From this, the electrolytic copper foil which contains the iodine which concerns on this invention has the characteristic which is hard to soften even when heated at high temperature, and it can understand that even if it is bent, there is little fall of tensile strength and it is hard to be broken.

Here, compared with the sample 5 and the sample 6 of Table 4, and the comparative sample 1, you may feel that there is no big difference in the tensile strength after 350 degreeC x 60-minute heating. By the way, when looking at the bending tensile strength after 180 degreeC * 60 minutes of heating, the value of the bending tensile strength of the sample 5 and the sample 6 is remarkably high compared with the comparative sample 1. Accordingly, it can be understood that the samples 5 and 6 exhibit a good tensile strength even when a wider range of temperature is applied than the comparative sample 1, and even if they are bent, the decrease in the tensile strength is small and it is difficult to break.

Moreover, when the change of the bending tensile strength after 180 degreeC * 60 minutes heating and 350 degreeC * 60 minutes heating of the sample 1, the sample 2, the sample 5, and the sample 6 which correspond to an Example, it turns out that it is as follows. In the case of the sample 1 and the sample 2, the bending tensile strength after heating at 350 degreeC x 60 minutes is high compared with the bending tensile strength after heating at 180 degreeC x 60 minutes. These iodine contents are 0.018 mass% and 0.019 mass%, and it is thought that the heat softening resistance to the heating as a material improves remarkably by containing this level of iodine. On the other hand, in the case of samples 5 and 6, the bending tensile strength after heating at 350 ° C for 60 minutes is considerably lower than the bending tensile strength after heating at 180 ° C for 60 minutes. These iodine content is 0.005 mass%, and in the case of this level of iodine content, it is thought that the heat softening resistance is not remarkably improved. However, also in the case of sample 5 and sample 6, compared with a comparative example, it can be said that the thermal softening resistance as a material certainly improved.

Consideration of characteristics as a negative electrode current collector of a lithium ion secondary battery 4: In consideration of 4, the physical properties of the foil after the 350 ° C heating test are examined in more detail, including an electrolytic copper foil obtained by using an electrolyte solution composition other than the compositions shown in Table 1. do. Table 5 shows the physical properties of the foil after the 350 ° C. × 60 minutes heating test for each composition of the electrolyte solution and the composition of the copper electrolyte solution. In addition, manufacturing conditions other than electrolyte composition are the same as that of an Example. Here, in consideration of the results in Tables 1 and 2, it can be understood that the S series (general name of 'Sample S-1 to Sample S-8') in Table 5 corresponds to the electrolytic copper foil according to the present invention. On the other hand, it is clear that C series (collectively, "sample C-1-sample C-4") of Table 5 does not correspond to the electrolytic copper foil which concerns on this invention. On the other hand, for reference, Sample S-2 is Sample 1 and Sample S-5 in Example, Sample 2 is Sample 2 in Example, and Sample C-1 is Comparative Sample 1 and Sample C-2 in Comparative Example. It is noted that the comparative sample 2 and the sample C-4 mentioned in the above are the comparative sample 4 described in the comparative example.

From Table 5, it can be understood that the 'S series' has a higher tensile strength after heat treatment at 350 ° C. for 60 minutes than the “C series”. In other words, in view of the tendency of the tensile strength, the 'S Series' produced by using a sulfuric acid acid copper sulfate electrolyte solution containing a predetermined amount of iodine has a sufficient softening of a tensile strength of 27 kgf / mm 2 or more for the harsh heating of 350 ° C × 60 minutes. It turns out that resistance is shown. In addition, the 'S series' exhibits a high tensile strength of 28 kgf / mm 2 or more even after bending. Moreover, the preferable form in "S series" corresponds to sample S-1 to sample S-6 which showed high tensile strength of 30 kgf / mm <2> or more in both heat-resistant tensile strength and heat-resistant bending tensile strength. And as a more preferable aspect, the sample S-1 to sample S-3 which showed high tensile strength of 40 kgf / mm <2> or more are corresponded to both a heat resistant tensile strength and a heat resistant bending tensile strength.

Consideration of Characteristics as Negative Current Collector of Lithium Ion Secondary Battery In Discussion 5, refer to Table 6 for an advantage of using an electrolytic copper foil containing iodine according to the present invention as a negative electrode current collector of a lithium ion secondary battery. I explain it. In description, these are compared using the sample 1-the sample 3 of an Example, the comparative sample 1, the comparative sample 2 of the comparative example, the comparative sample 4, the Colson alloy foil, and the rolled copper alloy foil. In Consideration 5, the conductivity is taken into consideration. The conductivity was measured using a four probe method based on JIS K 7194 using Agilent Technologies' B1500A Semiconductor Device Analyzer.

In order to extend the cycle life of a lithium ion secondary battery, it is necessary to make voltage loss by the electrical resistance of a negative electrode collector as small as possible, and to supply or collect an electron equally with respect to the negative electrode active material in a battery. It is thought that the physical property after the 350 degreeC x 60-minute heat processing of the electrolytic copper foil used as a negative electrode electrical power collector greatly affects this required characteristic.

That is, as Table 6 shows, the electrolytic copper foil containing the iodine which concerns on this application shows the high value of 30 kgf / mm <2> or more of tensile strength after 350 degreeC x 60-minute heat processing, and it is stable even after normal heating. High electrical conductivity is shown. On the other hand, although the electrolytic copper foil which does not contain iodine has high electrical conductivity, tensile strength is falling significantly by heating. Therefore, it can be judged that the electrolytic copper foil which does not contain iodine cannot endure expansion-shrinkage behavior which a negative electrode electrical power collector receives at the time of charge / discharge of a lithium ion secondary battery.

In addition, in Table 6, the Colson alloy foil and the rolled copper alloy foil were described for comparison. Colson alloy foil has a very good tensile strength after heating, but has low electrical conductivity due to the alloy composition. For this reason, when using as a negative electrode electrical power collector, since it is difficult to supply an electron equally to the whole negative electrode and to make reaction which collects lithium uniformly to a negative electrode active material, it is unpreferable.

In the case of the rolled copper alloy foil, at first glance, the balance between tensile strength and electrical conductivity seems to match. However, it turns out that an electrical conductivity is low even if compared with the sample of the Example which is an electrolytic copper foil, or the sample of a comparative example. In the case of using such a metallic foil as a negative electrode current collector, a part of the negative electrode current collector is overheated and partially annealed due to the heat generated when charging and discharging, and the tensile strength and the electrical resistance of the portion decrease. It is not preferable because the deformation as the negative electrode current collector becomes remarkable, and it becomes difficult to cause the reaction to collect lithium evenly on the negative electrode active material by supplying electrons evenly to the entire negative electrode.

As described above, it can be understood that the electrolytic copper foil containing iodine according to the present invention is very suitable for use as a negative electrode current collector of a lithium ion secondary battery even when compared with a comparative sample, a Colson alloy foil, and a rolled copper alloy foil of a comparative example. have.

Comprehensive judgment: It can be said that the electrolytic copper foil containing the iodine corresponded to this Example demonstrated above has the property which is hard to be broken even if it bends. Therefore, when such an electrolytic copper foil is used as a current collector material of a wound type battery employed in a lithium ion secondary battery, softening due to the thermal history applied in the manufacturing process of the battery is less likely to occur, and also due to heat generation during charge and discharge. It is hard to be affected, and furthermore, the deformation resistance against expansion and contraction behavior during charging and discharging is excellent. Therefore, the electrolytic copper foil containing iodine which concerns on this invention can be said to be a copper foil suitable as an electrical power collector material employ | adopted for a lithium ion secondary battery.

&Lt; Industrial Availability &gt;

The electrolytic copper foil which concerns on this invention contains 0.003 mass% or more of iodine which is not contained in the conventional electrolytic copper foil. The electrolytic copper foil containing this iodine shows the various characteristics stable even if chlorine content fluctuates.

And the physical property of the said electrolytic copper foil is hard to be softened even if it heats, and combines the favorable heat softening resistance and bending resistance characteristic calculated | required by the electrical power collector of a lithium ion secondary battery. Therefore, when this electrolytic copper foil is employ | adopted as an electrical power collector, it becomes possible to supply a high quality and long life lithium ion secondary battery to a market.

Claims (13)

As electrolytic copper foil obtained by electrolytic copper electrolyte solution,
The iodine content in an electrolytic copper foil is 0.003 mass%-0.03 mass%, The electrolytic copper foil characterized by the above-mentioned. The method of claim 1,
Electrolytic copper foil whose chlorine content exists in the range of 0.0006 mass%-0.0018 mass%. The method of claim 1,
Electrolytic copper foil whose chlorine content and iodine content satisfy | fill the relationship of the following formula (1).
[Equation 1]

The method of claim 1,
The electrolytic copper foil which has a precipitation surface in the value of Rzjis in the range of 0.70 micrometer-2.0 micrometers. The method of claim 1,
Electrolytic copper foil whose value of tensile strength (F0) is the range of 48 kgf / mm <2> -72 kgf / mm <_2> normally. The method of claim 1,
The electrolytic copper foil whose value of the tensile strength (F _a ) after heating after 180 degreeC x 60-minute heat processing is 38 kgf / mm <2> -72 kgf / mm <2>. The method of claim 1,
Normal tensile strength (F ₀₎ and the value after heating × 180 ℃ after 60 minutes heat treatment the tensile strength (F _a) delivered to the value, satisfying the relation of equation (2) below the foil of.
&Quot; (2) &quot;

The method of claim 1,
The electrolytic copper foil whose value of the tensile strength (F _b ) after heating after 350 degreeC x 60-minute heat processing is 30 kgf / mm <2> or more. The method of claim 1,
The electrolytic copper foil whose number of bendings in the bending resistance test after 180 degreeC x 60-minute heat processing is 3000 or more in the case where a bulk thickness is 18 micrometers / 1.8 micrometers. The surface treatment was given to the surface of the electrolytic copper foil in any one of Claims 1-9, The surface-treated copper foil characterized by the above-mentioned. As a manufacturing method of the electrolytic copper foil of any one of Claims 1-9,
A method for producing an electrolytic copper foil, wherein an acidic copper sulfate sulfate solution having an iodine concentration in the range of 1.5 mg / L to 15.0 mg / L is used as the copper electrolyte. 12. The method of claim 11,
The manufacturing method of the electrolytic copper foil using sulfuric acid acidic copper sulfate electrolyte solution whose chlorine concentration is 1.0 mg / L or less. The negative electrode active material was supported on the surface-treated copper foil of Claim 10, The negative electrode for lithium ion secondary batteries characterized by the above-mentioned.

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