JP5740055B2 - Electrolytic copper foil, electrode for lithium ion secondary battery using the electrolytic copper foil, lithium ion secondary battery using the electrode - Google Patents

Description

The present invention relates to an electrolytic copper foil having a low profile electrolytic deposition surface, high mechanical strength, and hardly changing mechanical strength even when heated at a high temperature.
The present invention relates to a secondary battery in which the electrolytic copper foil is used as a secondary battery current collector, an active material is deposited on the current collector to form a secondary battery electrode, and the electrode is incorporated.
The electrolytic copper foil of the present invention can be suitably used for rigid printed wiring boards, flexible printed wiring boards, electromagnetic wave shielding materials, and the like using the electrolytic copper foil as a conductive material.

  In this specification, electrolytic copper foil and electrolytic copper alloy foil (a foil containing an alloy of copper and a third metal in the foil, a foil containing the third metal in a solid solution state in the foil) are distinguished and expressed. When it is not necessary, it is expressed as “electrolytic copper foil”, and mechanical strength indicates tensile strength.

  Copper foil is used in various fields such as rigid printed wiring boards, flexible printed wiring boards, electromagnetic wave shielding materials, battery current collectors, and the like.

  Among these fields, in the field of printed wiring boards (flexible wiring boards, hereinafter referred to as “FPC”) bonded to polyimide films, hard disk (hereinafter referred to as “HDD”) suspension materials or tape automation. The bonding (hereinafter referred to as “TAB”) material has been required to improve the strength of the copper foil.

  The suspension mounted in the HDD is a wiring-integrated suspension in which the flying head buoyancy and the positional accuracy are stable with respect to the disk as the storage medium from the wire type suspension that has been used conventionally as the capacity of the HDD increases. The majority have been replaced.

This wiring-integrated suspension has the following three types.
a. A type in which a flexible printed circuit board called FSA (flex suspension assembly) method is processed and bonded using an adhesive b. Type C.TSA (Trace Suspension / Assembly) type that processes a laminated body made of stainless steel foil-polyimide resin-copper foil into a predetermined shape by etching

  The TSA suspension allows easy formation of flying leads by laminating copper alloy foils with high strength, has a high degree of freedom in shape processing, and is relatively inexpensive and has good dimensional accuracy. Widely used.

  The laminate formed by the TSA method is manufactured using a material having a stainless steel foil thickness of about 12 to 30 μm, a polyimide layer thickness of about 5 to 20 μm, and a copper alloy foil thickness of about 7 to 14 μm.

  In the production of the laminate, first, a polyimide resin solution is applied onto a stainless steel foil as a base. After the application, the solvent is removed by preheating, and then further heat treatment is performed to perform imidization. Subsequently, a copper alloy foil is superposed on the imidized polyimide resin layer and laminated by thermocompression bonding at a temperature of about 300 ° C. to produce a laminate composed of stainless steel layer / polyimide layer / copper alloy layer.

During the heating at about 300 ° C., the stainless steel foil hardly changes in dimensions. However, when a conventional electrolytic copper foil is used, the electrolytic copper foil is annealed at a temperature of about 300 ° C., recrystallization proceeds, softens, and a dimensional change occurs. For this reason, the laminate is warped after lamination, and the dimensional accuracy of the product is lowered.
In order to prevent warping of the laminate after lamination, provision of a copper alloy foil that is as small as possible in dimensional change during heating is required.

In the TAB material, as with the HDD suspension material, it is required to increase the strength of the copper foil and reduce the roughness of the foil surface.
In a TAB product, a plurality of terminals of an IC chip are directly bonded to inner leads (flying leads) arranged in a device hole located substantially at the center of the product. This bonding is performed by applying a constant bonding pressure by instantaneously energizing and heating using a bonding apparatus. At this time, there is a problem that the inner lead obtained by etching the electrolytic copper foil is stretched by being pulled by the bonding pressure.
Furthermore, if the strength of the electrolytic copper foil is low, the inner lead may sag due to plastic deformation and may break if it is significant.
Therefore, in order to reduce the line width of the inner lead, the electrolytic copper foil to be used is required to have a roughened surface with low roughness and to have high strength.

  Also in this case, it is necessary that the copper foil has high strength in a normal state (normal temperature / normal pressure state) and has high strength even after being heated. In the case of a TAB application, a two-layer or three-layer FPC in which a copper foil and a polyimide are bonded together is used. In the case of bonding the polyimide to the copper foil in the three-layer FPC, an epoxy adhesive is used and the bonding is performed at a temperature of about 180 ° C. In a two-layer FPC using a polyimide-based adhesive, bonding is performed at a temperature of about 300 ° C.

  Even if the electrolytic copper foil has a high mechanical strength in a normal state, it does not make sense if the electrolytic copper foil softens when bonded to polyimide. Conventional high-strength electrolytic copper foil has high mechanical strength in the normal state, and the mechanical strength hardly changes even when heated at around 180 ° C. However, when heated at about 300 ° C, it is annealed and recrystallization proceeds. , It softens rapidly and the mechanical strength decreases. Such a copper foil is not suitable for TAB applications.

Further, the copper foil is used as a current collector for a battery such as a lithium ion secondary battery. A lithium ion secondary battery is basically composed of a positive electrode, a negative electrode, and an electrolytic solution. The negative electrode is formed by coating the surface of a copper foil used as a current collector with a negative electrode active material layer.
As a method for forming the negative electrode, a slurry obtained by dissolving a negative electrode active material and a binder resin (added for the purpose of binding the active material and the copper foil substrate) in a solvent is applied onto the copper foil substrate, and then the binder resin is formed. A method of forming by pressing after drying at a temperature equal to or higher than the curing temperature is generally used.

As the binder resin, polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR) and the like are widely used.
In recent years, active materials made of silicon, tin, germanium alloy materials with high theoretical capacity, which are attracting attention as the capacity of batteries increases, have a large volume expansion coefficient associated with lithium insertion / extraction during charge / discharge, The binder resin described above has insufficient strength. Therefore, a polyimide resin having a high adhesive strength with a copper substrate has been preferably used. However, unlike the binder resin described above, the polyimide resin has a high curing temperature of about 300 ° C., and a negative electrode current collector (copper foil) that can withstand this heating condition is required.

  Thus, in the FPC field and the secondary battery field, a polyimide resin having a high curing temperature of about 300 ° C. has been used as a binder, and a copper foil that can withstand this heating condition is required. .

  By the way, an electrolytic solution containing copper sulfate and sulfuric acid is used as the electrolytic solution for the electrolytic copper foil, and various additions are made to the plating bath for the purpose of making the copper foil surface bright and smooth, reducing the stress of the copper foil, etc. An agent has been added. When the additive is not used, the surface form and mechanical properties required for the copper foil cannot be obtained, so the additive is highly important. In particular, since the copper sulfate plating bath is a simple acidic bath, it is inferior in throwing power and it is difficult to produce a preferable electrolytic copper foil without an additive. As additives used in copper sulfate plating baths, chlorine ions, polyoxyethylene surfactants, smoothing agents, brighteners such as organic sulfides, glue, gelatin, etc. have been proposed and used. .

  Plating concentrates on high current areas where electricity can easily flow without adding chlorine or additives to the copper sulfate plating bath (locations close to the anode, the end of the cathode, the tip of sharp objects, etc.) State (plated surface becomes more uneven).

  However, generally, when chlorine ions are present in the electrolytic solution, it is difficult to change the characteristics of the copper foil by mixing a specific metal in the copper foil. That is, in an electrolytic solution that does not contain chlorine ions, other metals can be mixed into the copper foil, and other metals can be mixed (alloyed) to change the characteristics of the copper foil. When chlorine ions enter, it becomes difficult for other metals to be mixed into the copper foil, and it becomes difficult to change the characteristics of the copper foil with other metals.

  For example, Patent Documents 1 and 2 disclose a method of producing an electrolytic copper foil with an electrolytic solution in which tungsten is added to a sulfuric acid-copper sulfate electrolytic solution, and further glue and chloride ions are added. It describes that it is possible to produce a copper foil having a hot elongation rate of 3% or more, a rough surface having a large roughness and less pinholes.

  Therefore, the present inventors repeated an experiment in which tungsten was added to a sulfuric acid-copper sulfate electrolytic solution, and further glue and chloride ions were added, and heat at 180 ° C., which is the purpose of the electrolytic copper foil disclosed in Patent Document 1. It was possible to produce a copper foil having an interstitial elongation of 3% or more, a large rough surface, and few pinholes. However, when this copper foil was heat-treated at 300 ° C. for 1 hour (hereinafter also referred to as “300 ° C. × 1 hour”), it was found that the mechanical strength could not be maintained. Therefore, when this copper foil was analyzed, it was found that tungsten was not co-deposited in the electrodeposited copper.

  That is, in the methods of Patent Documents 1 and 2, electrodeposition was performed with an electrolytic solution in which tungsten was added to a sulfuric acid-copper sulfate electrolytic solution, and further, glue 10 mg / L or less and chlorine ions 20 to 100 mg / L were added. As a result, tungsten did not eutectide, and it was impossible to produce an electrolytic copper alloy foil that retained high mechanical strength even when heated at 300 ° C.

As described above, the electrolytic copper foil is made by adding chlorine and an organic compound as additives to an electrolytic solution containing copper sulfate and sulfuric acid.
Many organic additives usually have an effect of suppressing crystal growth, and are considered to be taken into crystal grain boundaries.
In this case, the mechanical strength tends to improve as the amount of the organic additive taken into the crystal grain boundary increases (Non-patent Document 1: Shiga Shoji; Metal Surface Technology Vol31, No10, p573 (1980)).

  As described in Non-Patent Document 1, the organic additive incorporated into the electrolytic copper foil improves the mechanical strength of the copper foil. This factor can be considered that the organic additive is mainly taken into the crystal grain boundary and improves the mechanical strength at room temperature. However, when the electrolytic copper foil incorporating the organic additive is heated at a high temperature of 300 ° C. or higher, the mechanical strength decreases. The cause is presumed that the organic additive is thermally decomposed, resulting in a decrease in mechanical strength.

On the other hand, a rolled copper alloy foil is used as a copper foil that satisfies the above requirements. The rolled copper alloy foil is not easily annealed at a temperature of about 300 ° C., has little dimensional change during heating, and little mechanical strength change.
However, rolled copper foil is more expensive than electrolytic copper foil, and it is difficult to satisfy requirements such as width and thickness.

Therefore, the present inventors have an electrolytic copper alloy foil that has a low profile surface bonded to a polyimide resin base material and excellent mechanical strength, and an electrolytic copper alloy foil that is suitable for applications using a polyimide resin as a binder resin. Attempts were made to add various metals to the copper foil to improve its heat resistance.
However, it has been difficult to incorporate a metal capable of improving the heat resistance of the copper foil into the electrolytic copper foil. That is, there has been a problem that the metal that improves the heat resistance of the copper foil is a metal that is difficult to incorporate into the copper foil.

Japanese Patent No. 3238278 JP-A-9-67693

Shiga Shoji; Metal Surface Technology Vol31, No10, p573 (1980)

An object of the present invention is to provide an electrolytic copper foil having a tensile strength at room temperature of 650 MPa or more, a tensile strength measured at room temperature after heat treatment at 300 ° C. for 1 hour, 450 MPa or more, and a conductivity of 60% IACS or more. .
Another object of the present invention is to provide an electrolytic copper foil having excellent mechanical strength in applications in the field of printed wiring boards bonded to polyimide films.
Furthermore, the present invention is a lithium ion secondary battery using a Si or Sn alloy-based active material, and adheres between the current collector (copper foil) and the active material against large expansion and contraction of the Si or Sn alloy-based active material An object of the present invention is to provide an electrolytic copper foil that retains its properties with a polyimide binder and does not deform the current collector (copper foil).

As a result of earnest research, the inventors have overcome the above-mentioned problems and succeeded in incorporating at least one kind of metal present as an oxide in an acidic solution having a pH of 4 or less into the electrolytic copper foil. The present inventors have succeeded in producing an electrolytic copper foil having a tensile strength of 650 MPa or more at a normal temperature, a tensile strength of 450 MPa or more and a conductivity of 60% or more measured at a normal temperature after heat treatment at 300 ° C. for 1 hour.
In addition, the present inventors have made it possible to use a polyimide binder as an HDD suspension material, a TAB material, or an active material that repeats large expansion and contraction of a Si or Sn alloy-based active material. We succeeded in developing electrolytic copper foil that does not deform as (copper foil).

The electrolytic copper foil of the present invention contains a metal present as an oxide or an oxide thereof in an acidic solution having a pH of 4 or less in the untreated copper foil, and the content of the metal or the metal constituting the oxide is It is 0.0001 to 1.320 % by mass , and contains 0.005 to 0.04 % by mass of chlorine.

  The metal component of the electrolytic copper foil is preferably one or more metal components selected from titanium (Ti), molybdenum (Mo), vanadium (V), bismuth (Bi), and tellurium (Te).

  The electrolytic copper foil preferably has a tensile strength of 650 MPa or more at room temperature, and a tensile strength measured at room temperature after heat treatment at 300 ° C. for 1 hour is 450 MPa or more.

  It is preferable that the electrical conductivity of the electrolytic copper foil at room temperature is 60% IACS or more.

  The electrode for lithium ion secondary batteries of the present invention is characterized by using the electrolytic copper foil of the present invention as a current collector.

  The lithium ion secondary battery of the present invention is characterized in that the battery electrode of the present invention is a negative electrode.

  According to the present invention, it was possible to provide an electrolytic copper foil that has a high mechanical strength in the normal state and hardly undergoes thermal deterioration even after heat treatment at 300 ° C. for 1 hour.

It is an apparatus schematic of SAXS (USAXS).

The electrolytic copper foil of the present invention contains a metal present as an oxide in an acidic solution having a pH of 4 or less as ultrafine particles of the oxide or ultrafine particles of a reduced metal, and contains 0.005 to 0.04 wt% of chlorine. It is characterized by doing.
In the present embodiment, titanium (Ti), molybdenum (Mo), vanadium (V), bismuth (Bi), and tellurium (Te) can be preferably used as the metal present in the acidic solution having a pH of 4 or less.
That is, the electrolytic copper foil of the present embodiment is an electrolytic copper foil that contains at least one of Ti, Mo, V, Bi, and Te, and the balance is substantially made of copper.
The above-mentioned “contains at least one of Ti, Mo, V, Bi, and Te” means that each metal is contained alone or two or more of them are contained simultaneously. In addition, “the balance is substantially made of copper” means that copper contains inevitable impurities derived from raw materials or the like, or allows a trace amount of additives due to an electrolytic foil manufacturing process or the like to be included. Is the meaning.

The amount of metal present as an oxide in an acidic solution having a pH of 4 or less contained in the electrolytic copper foil is preferably 0.0001 wt% or more.
When the content of a metal present as an oxide in an acidic solution having a pH of 4 or less is 0.0001 wt% or less, the effect of adding the metal hardly appears. In addition, the more preferable range of content of the said metal in foil is 0.001-1.320 wt%.
The reason why the metal contained in the electrolytic copper foil is limited to a metal present in an acidic solution having a pH of 4 or less is that the pH of the electrolytic solution is 4 or less, and the metal present as an oxide in such an acidic electrolytic solution is copper. This is because it is easily taken into the foil.
That is, in the copper foil containing less than 0.0001 wt% of the metal, the mechanical strength measured at room temperature after the heat treatment at 300 ° C. for 1 hour shows a tendency for the strength to decrease as in the case where the metal is not contained.

  In this specification, “a metal present as an oxide at pH 4 or lower” means a pH of 4 or lower in the potential-pH diagram shown in Pergamon Press (1966) by M. Pourbaix's Atlas of electrochemical equilibria in aqueous solutions. In this case, the added metal component is detected as solid particles in the particle size distribution measurement by DLS (Dynamic Light Scattering) of the electrolyte added with the metal.

  In order to use the electrolytic copper foil as a current collector for a battery, particularly as a current collector for an electrode for a lithium ion secondary battery, a copper foil having higher mechanical strength is required. Therefore, for use as a current collector, the amount of the metal contained in the electrolytic copper foil is preferably 0.001 or more, preferably 1.320 wt% or less.

The electrolytic copper foil of this embodiment contains 0.005 to 0.04 wt% of chlorine.
In the present embodiment, the electrolytic copper foil having a chlorine content of 0.005 wt% or less needs to keep the chlorine concentration in the electrolytic bath for producing the electrolytic copper foil low, so that pinholes are generated in the foil production. This is not preferable because pinholes exist in the copper foil that has been formed. Further, an electrolytic copper foil having a chlorine content of 0.04 wt% or more is not preferable because curling tends to occur in the copper foil.
Accordingly, the chlorine content is preferably 0.005 to 0.04 wt%.

The present inventors have sought various manufacturing methods in which the metal is contained in a copper foil as a copper alloy or mixed as a simple substance. As a result, in an electrolytic solution containing chlorine ions, even if a large amount of the metal is added to the solution, the metal is not taken into the foil-formed copper foil, and naturally the foil is made with such an electrolytic solution. The mechanical strength of the copper foil after heating at normal temperature and after heating was not improved.
However, even when chlorine ions were added to the electrolytic solution, it was found that if the thiourea compound was added to the solution, the metal was taken into the foil depending on the foil production conditions.

Based on these findings, we succeeded in producing an electrolytic copper foil excellent in heat resistance by producing an electrolytic copper foil under the following conditions.
That is, by forming a copper foil having a tensile strength of 450 MPa or more measured at room temperature after heat treatment at 300 ° C. for 1 hour under the following basic electrolytic bath composition and electrolysis conditions, electrolytic copper in which the metal is taken into the foil The foil can be made.

Basic electrolytic bath composition:
Cu = 50 to 150 g / L
H ₂ SO ₄ = 20 to 200 g / L
Electrolysis conditions:
Current density = 30-100 A / dm ²
Liquid temperature = 30-70 ° C.

Additives added to the sulfuric acid-copper sulfate-based copper electrolyte are as follows.
Additive A: Thiourea compound = 3 to 20 mg / L
Additive B: At least one salt of Ti, Mo, V, Bi, Te (when adding a plurality of metals as Ti, Mo, V, Bi, Te, the total amount thereof) = 100 to 10,000 mg / L
Additive C: Chlorine ion = 1-100 mg / L

Additive A: A thiourea compound is an organic compound having the following structure.
> N−C (= S) −N <
Examples of thiourea compounds are thiourea, N, N-diethylthiourea, tetramethylthiourea, and ethylenethiourea. However, these only exemplify those used in the examples described later, and any compound can be used as long as it has the structural characteristics as described above and exhibits the same effect. Is possible.

  Additive B: selected from metal salts of Ti, Mo, V, Bi, and Te that are dissolved in an acidic electrolyte containing copper sulfate and sulfuric acid and exist as oxides. For example, sodium salt, ammonium salt, potassium salt and the like.

  Additive C: The addition of chlorine ions is selected from compounds that dissolve in an electrolytic solution containing copper sulfate and sulfuric acid. For example, hydrochloric acid, sodium chloride, potassium chloride and the like.

The reason for using thiourea compounds as organic additives is that these compounds easily change to a [= S] structure in the solution, and the [= S] structure is preferentially adsorbed on copper, and the organic molecules By forming an adsorption layer and adsorbing at least one oxide of Ti, Mo, V, Bi, Te on the adsorption layer, in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, Te This is because at least one of the metals present as oxides is incorporated into the foil together with the thiourea compound.
Metals present as oxides in acidic solutions of pH 4 or lower, such as Ti, Mo, V, Bi, Te, etc., exist as oxides in acidic solutions. However, copper deposition using an electrolytic solution containing chlorine Since chloride ions are coated on the precipitation surface, metal oxides present as oxides in acidic solutions of pH 4 or lower such as Ti, Mo, V, Bi, Te, etc. are not adsorbed by copper, but into the foil. Ingestion does not occur. When a thiourea compound is added to the electrolytic solution, the [= S] structure is preferentially adsorbed on the copper rather than the chlorine ions to form an organic molecule adsorption layer on the copper. By adsorbing metal oxides present as oxides in an acidic solution of pH 4 or lower such as Ti, Mo, V, Bi, Te, etc. on the adsorption layer, pH 4 of Ti, Mo, V, Bi, Te, etc. It is assumed that the metal present as an oxide in the following acidic solution is taken into the foil together with the thiourea compound.

  As described above, the electrolytic copper foil of the present invention contains a metal, a thiourea compound, and chlorine that are present as oxides in an acidic solution having a pH of 4 or less, such as Ti, Mo, V, Bi, and Te. It forms by electrolytic deposition from the electrolyte solution containing. When copper is electrolytically deposited in a sulfuric acid-copper sulfate electrolytic solution containing a metal, a thiourea compound, and chlorine present as an oxide in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, Te, Ti, , Mo, V, Bi, Te, and other metal oxides that exist as oxides in acidic solutions with a pH of 4 or less are adsorbed together with the thiourea compound to the copper grain boundaries to suppress the growth of crystal nuclei. It is considered that crystal grains are refined (low profile) to form an electrolytic copper foil having a large mechanical strength in a normal state.

Metal oxides present as oxides in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, Te, etc. present at the grain boundaries are not bonded to or absorbed by the bulk copper crystals. , Mo, V, Bi, and Te oxides are considered to remain at the grain boundaries.
Therefore, even when an electrolytic copper foil containing a metal present as an oxide in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, Te is heated at a high temperature of about 300 ° C., Ti, Mo, V, Metal oxides that exist as oxides in acidic solutions such as Bi and Te that have a pH of 4 or less remain at the grain boundaries, and the copper fine crystals recrystallize due to heat and prevent the crystals from becoming coarse. Conceivable.

  Therefore, the electrolytic copper foil of the present invention has a low profile and a small decrease in mechanical strength even after being heated at a high temperature of about 300 ° C. Exhibits excellent characteristics not seen in electrolytic copper foils manufactured with liquid.

In addition, as disclosed in Patent Documents 1 and 2, an electrolyte containing chlorine ions contains metal and glue existing as oxides in an acidic solution having a pH of 4 or less, such as Ti, Mo, V, Bi, and Te. Even if it added, the metal which exists as an oxide in the acidic solution of pH 4 or less, such as Ti, Mo, V, Bi, and Te, was not taken in in electrolytic copper foil.
As a matter of course, the mechanical strength of the electrolytic copper foil made with such an electrolytic solution greatly decreased after being heated at a high temperature of about 300 ° C.

When a thiourea compound is added to the electrolyte, even if chlorine ions are contained, depending on the foil production conditions, the metal present as an oxide in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, Te, etc. It is considered that the thiourea compound added to the sulfuric acid-copper sulfate electrolytic solution forms a complex with the metal element and chlorine in the electrolytic solution.
When the metal present as an oxide in an acidic solution of pH 4 or lower such as Ti, Mo, V, Bi, Te is not added, the metal element added to the electrolytic solution for the electrolytic copper foil foil is copper. It is. Accordingly, a copper-thiourea compound is formed in the electrolytic solution containing copper sulfate and sulfuric acid. When an electrolytic copper foil is formed by copper electrodeposition using this electrolytic solution, the copper-thiourea compound is adsorbed on the grain boundaries, suppressing the growth of crystal nuclei, making the grains finer, and increasing the mechanical strength in the normal state. The provided electrolytic copper foil is formed.

However, since this copper foil is a copper-thiourea compound, the substance present at the crystal grain boundary is bonded or absorbed with the bulk copper crystal, and the substance present at the crystal grain boundary is the thiourea compound. Therefore, it is considered that this thiourea compound decomposes when exposed to a high temperature of about 300 ° C., and as a result, the mechanical strength decreases.
In general, when copper foil is heated at a high temperature of about 300 ° C., the reason why the tensile strength is remarkably lowered is that the compound existing at the grain boundary is an organic compound as described above, and the organic compound is heated by heating at about 300 ° C. It is considered that the mechanical strength decreases because it is easily decomposed.

  In the present invention, an electrolytic solution containing copper sulfate and sulfuric acid contains at least one kind of metal, thiourea compound, and chlorine, which are present as oxides in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, Te. Since the copper electrodeposition is performed with the electrolytic solution containing to form a copper foil, the metal present as an oxide in an acidic solution of pH 4 or less such as Ti, Mo, V, Bi, Te, etc. added to the electrolytic solution is an oxide. And adsorb on copper together with thiourea compounds. The growth of crystal nuclei is suppressed and the crystal grains are refined by the metal oxides and thiourea compounds present as oxides in an acidic solution of pH 4 or lower such as adsorbed Ti, Mo, V, Bi, Te. An electrolytic copper foil having a large mechanical strength in a normal state is formed.

  Thus, the electrolytic copper foil of the present invention has metal oxides and thiourea compounds present as oxides in an acidic solution of pH 4 or lower such as Ti, Mo, V, Bi, Te, etc., at the grain boundaries. Therefore, unlike the case of a copper-thiourea compound, a metal oxide existing as an oxide in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, Te is bonded to a bulk copper crystal, or It is considered that the metal oxides and thiourea compounds existing as oxides in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, and Te remain at the grain boundaries without being absorbed. For this reason, even when exposed to a high temperature of about 300 ° C., metal oxides existing as oxides in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, Te, etc. remain at the crystal grain boundaries. It works to prevent fine crystals from being recrystallized by heat and coarsening of the crystals.

From this point of view, the size of precipitates such as oxides is preferably 0.5 to 20 nm because the pinning effect is most exhibited and the growth of crystal grains can be suppressed even at high temperatures. When the size of the precipitate is 20 to 50 nm, the pinning effect is exhibited, but it cannot be said that the crystal growth is completely suppressed. Even if the size of the precipitate is 50 to 100 nm, the pinning effect is exhibited, but a large number of crystal grains are observed.

  The amount of metal present as an oxide in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, Te, etc. added to the electrolyte is preferably 100 to 10,000 mg / L. The amount of metal added as an oxide in an acidic solution having a pH of 4 or less, such as Ti, Mo, V, Bi, Te, is set to 100 mg / L or more. Below this, Ti, Mo, V, Bi, Te, etc. The effect of containing a metal present as an oxide in an acidic solution having a pH of 4 or less does not appear, and if it exceeds 10,000 mg / L, a precipitate derived from an additive element tends to be generated in a bath. Therefore, it is preferable that the addition amount of the metal which exists as an oxide in the acidic solution of pH 4 or less, such as Ti, Mo, V, Bi, Te, is 100 to 10,000 mg / L.

In the present invention, the addition of a thiourea compound succeeded in incorporating Ti, Mo, V, Bi, and Te into the copper foil.
The amount of thiourea compound to be added is 3 to 20 mg / L. If it is less than 3 mg / L, it exists as an oxide in an acidic solution of Ti, Mo, V, Bi, Te or the like in copper foil in a copper foil. The tensile strength at room temperature after heat treatment at 300 ° C. for 1 hour becomes 450 MPa or less, and when added over 20 mg / L, Ti, Mo, V, Bi, This is because a metal existing as an oxide in an acidic solution of pH 4 or lower such as Te enters too much, the tensile strength becomes too high, or the elongation becomes small, and undesirable properties appear. Therefore, the addition amount is 3 to 20 mg / L. This is a preferred range.

  The addition amount of chloride ions is 1 to 100 mg / L. Addition of less than 1 mg / L of chlorine ions is not preferable because many pinholes are generated in the foil, and addition of more than 100 mg / L of chloride ions causes a significant increase in surface roughness or curling. Therefore, the chlorine ion is preferably in the range of 1 to 100 mg / L, particularly preferably 15 to 50 mg / L. By making a foil with an electrolytic solution containing such an amount of chlorine ions, 0.005 to 0.04 wt% of chlorine can be contained in the electrolytic copper foil.

The electrolytic copper foil is copper sulfate to which at least one kind of metal existing as an oxide in an acidic solution of pH 4 or lower such as Ti, Mo, V, Bi, Te, a thiourea compound, and a chlorine ion is added in the specified amount. Using the solution as the electrolytic solution, the noble metal oxide-coated titanium as the anode, and the titanium rotating drum as the cathode, electrolytic foil treatment is performed under the conditions of a current density of 30 to 100 A / dm ² and a liquid temperature of 30 to 70 ° C.

Preferably, the mechanical strength at room temperature after 300 ° C. × 1 hour heat treatment of the electrolytic copper foil to be formed by adding ammonium ion or nitrate ion to the electrolytic solution of the present invention can be further improved. .
The amount of ammonium ions added to the electrolytic solution is suitably 1 to 15 g / L, and the amount of nitrate ions is suitably 50 to 200 mg / L. In order to further improve the mechanical strength at normal temperature after the heat treatment, it is preferable to add ammonia ions or nitrate ions to the electrolytic solution.

  By using the above-mentioned electrolytic solution and making a foil at an appropriate current density and liquid temperature, electrolytic copper having a tensile strength at room temperature after heat treatment at 300 ° C. for 1 hour of 450 MPa or more and a conductivity of 60% IACS or more. A foil can be produced.

  As described above, the current collector (copper foil) constituting the negative electrode current collector of the lithium ion secondary battery needs to withstand a heat treatment of 300 ° C. × 1 hour usually when a polyimide binder is used. That is, an active material composition prepared by adding a solvent to a mixture of an active material, a conductive material and a binder to a surface of a current collector for a lithium ion secondary battery and applying a lithium ion secondary battery through a drying process. The negative electrode of the secondary battery is used. In the drying process, a heat treatment of 300 ° C. × 1 hour is required. As a copper foil that withstands the heating conditions of this drying process and withstands expansion and contraction due to charge / discharge cycles of the active material, the tensile strength measured at room temperature after heat treatment at 300 ° C. for 1 hour is 450 MPa or more. Satisfactory performance is required.

  In addition, active materials such as Si and Sn have poor electronic conductivity compared to active materials such as carbon. If the conductivity of the active material is poor, the internal resistance of the electrode increases, and the cycle characteristics deteriorate. Therefore, the copper foil as a current collector is required to have a conductivity of 60% or more.

  The copper foil containing a metal present as an oxide in an acidic solution having a pH of 4 or less such as Ti, Mo, V, Bi, and Te of the present invention satisfies various characteristics required by the current collector for a secondary battery. Therefore, such an electrolytic copper foil is used as a current collector, and silicon, germanium, tin, or an alloy compound thereof or an active material containing them as a main component is deposited on the current collector as an electrode. An excellent lithium ion secondary battery can be manufactured and provided.

<Example>
An electrolytic solution containing the following copper sulfate and sulfuric acid is used as a basic bath composition, and an electrolytic solution to which chlorine ions, Ti, Mo, V, Bi, Te, and thiourea organic additives in amounts shown in Table 1 are added is used. An electrolytic copper foil was made under the following electrolysis conditions using a noble metal oxide-coated titanium as an anode and a titanium rotating drum as a cathode.
Basic electrolytic bath composition Cu = 50 to 150 g / L
H ₂ SO ₄ = 20 to 200 g / L
Electrolysis conditions Current density 30-100 A / dm ²
Temperature 30 ~ 70 ℃

  In Table 1, “after heating” is a result of measurement at room temperature after heat treatment at 300 ° C. for 1 hour in an inert gas atmosphere. “Before heating” is the result of measurement at room temperature before the heat treatment. The same applies to the following embodiments.

Rust prevention treatment The electrolytic copper foil thus formed was subjected to a rust prevention treatment under the following conditions.
The formed electrolytic copper foil (untreated copper foil) was immersed in a CrO ₃ ; 1 g / L aqueous solution for 5 seconds, subjected to chromate treatment, washed with water and dried.
Although the chromate treatment is performed here, it goes without saying that the silane coupling agent treatment may be performed after the benzotriazole-based treatment, the silane coupling agent treatment, or the chromate treatment.

<Comparative example>
Using an electrolyte containing copper sulfate and sulfuric acid with the addition of chlorine, Mo, Fe, Ni, ethylenethiourea or glue in the amounts shown in Table 2, the noble metal oxide-coated titanium as the anode, and the titanium rotating drum as the cathode, An electrolytic copper foil was made under the following electrolysis conditions.
Electrolysis conditions Current density 30-100 A / dm ²
Temperature 30 ~ 70 ℃
The copper foil thus produced was subjected to the same surface treatment as in the example.

The following test was implemented about the produced copper foil.
Measurement of content of Ti, Mo, V, Bi, Te, Fe, Ni in copper foil Content of Ti, Mo, V, Bi, Te is obtained by dissolving a certain weight of electrolytic copper foil with acid, Ti, Mo, V, Bi, and Te in the solution were determined by ICP emission spectroscopy.
Equipment used: ICPS-7000 (Shimadzu Corporation)
Measurement of tensile strength of copper foil The tensile strength of copper foil was measured before and after heating the foil based on IPC-TM-650.
Equipment used: AG-I (Shimadzu Corporation)

Measurement of electrical conductivity The electrical conductivity was calculated by first measuring the resistance value of a 20 mm × 200 mm copper foil and then dividing the measured resistance value by the cross-sectional area of the copper foil.
Measurement of chlorine content Chlorine content was calculated by dissolving a certain weight of electrolytic copper foil with an acid and then quantifying the chlorine in the solution by silver nitrate titration.

Analysis of oxides The chemical bonding state and electronic state of oxides contained in the electrolytic copper alloy were analyzed by the XAFS (X-ray Absorption Fine Structure) method. In the XAFS method, a sample is irradiated with X-rays while changing X-ray energy, and a chemical bond state and an electronic state in the sample can be analyzed from the obtained X-ray absorption spectrum.
Other methods for obtaining an X-ray absorption spectrum include a transmission method for obtaining an X-ray absorption spectrum from the intensity of incident X-rays and the intensity of transmitted X-rays, and the intensity of fluorescent X-rays emitted from a sample along with X-ray absorption. There is a fluorescence method for measuring.
When an additive element such as a metal material is to be analyzed, the amount of addition is very small, and it is difficult to obtain an XAFS spectrum by the transmission method. The fluorescent method described above is effective in such a case. As a feature of the fluorescence method, XAFS measurement can be performed even with a trace amount of elements by taking a wider X-ray irradiation area than the optical axis system.
The purpose of this measurement is to know the chemical bonding state and electronic state of Ti, Mo, V, Bi, and Te in the high-strength copper foil. The amount of Ti, Mo, V, Bi, and Te is very small, and the transmission The fluorescence method was selected because it was difficult to obtain an XAFS spectrum by this method.
Regarding the measurement, SPring-8 industrial use beam line BL14B2 was used. The measured X-ray energy range was 10000-10434 eV.

  When the measurement result of the foil of an Example and the measurement result of each oxide of Ti, Mo, V, Bi, and Te prepared for the comparison were compared, Ti, Mo, V, Bi, and Te containing copper foil of The spectrum has a peak in the energy region that almost coincides with the spectrum of the oxide, not the metal. From this, it was confirmed that Ti, Mo, V, Bi, and Te elements in the electrolytic copper foil were contained in an oxide state.

Measurement of the particle size of the metal component in the foil The particle size of the metal (inorganic additive) in the foil is determined by SAXS (small angle X-ray scattering) and USAXS (ultra small angle X-ray scattering). X-ray scattering) was determined by analysis. The SAXS / USAXS measurement was performed at the industrial beam line BL19B2 of Spring-8.

  FIG. 1A shows a simple optical axis diagram of SAXS (USAXS) measurement. Incident X-rays 14 generated from the X-ray source 13 including the shutter 15 are irradiated to the sample 27 through the monochromator 17, the first pinhole 19, the second pinhole 21, and the third pinhole 25. From incident X-rays 14 irradiated on the sample 27, transmitted X-rays 29 that pass through the sample 27 and scattered X-rays 31 scattered by the sample 27 are generated. The detector 35 is provided at the end of the optical axis and detects transmitted X-rays 29 or scattered X-rays 31.

  When the scattered X-ray 31 is measured by the detector 35, as shown in FIG. 1B, the incident X-ray 14 is irradiated to the sample 27 without passing through the attenuator 23, and the transmitted X-ray 29 is irradiated by the beam stopper 33. The light is shielded and the scattered X-ray 31 is measured by the detector 35.

  When measuring the transmitted X-ray 29 with the detector 35, as shown in FIG. 1C, the intensity of the incident X-ray 14 is weakened with the attenuator 23, and then the sample 27 is irradiated with the incident X-ray 14. The transmitted X-ray 35 is measured by the detector 35 without shielding the transmitted X-ray 29 by the beam stopper 33.

Let L be the distance from the sample 27 to the detector 35. A location where the transmitted X-ray 29 transmitted through the sample 27 reaches the detector 35 is denoted by O, and a location where the scattered X-ray 31 scattered from the sample 27 at the angle θ reaches the detector 35 is denoted by A. If AO = r, then tan θ = r / L and θ can be obtained. The horizontal axis of the SAXS and USAXS data is described by q (nm ⁻¹ ) represented by the formula (1).
q = 4πsin θ / λ (1)

  λ is the wavelength of incident X-rays. In the measurement, λ = 0.068 nm, the distance from the sample to the detector was L = 4.2 m (SAXS), and L = 42 m (USAXS). The measurement range is q = 0.05-4 (nm-1). The detector used was a semiconductor two-dimensional detector Pilatus. After performing SAXS measurement, it was confirmed that there was no anisotropy by looking at the mapping of the intensity of two-dimensional X-rays, and one-dimensionalization was performed. It was confirmed that the X-ray intensity was different between q = 0.4-2 as compared with copper foil and electrolytic copper alloy copper foil. This suggests that inclusions of 10 nm or less are present in the electrolytic copper alloy copper foil.

For example, regarding Mo-containing electrolytic copper foil, the fine particles are considered to be MoO ₃ from the results of TEM observation and XAFS measurement. Therefore, X-ray scattering from MoO ₃ can be extracted by subtracting the SAXS intensity of the pure copper foil from the SAXS data of the Mo-containing electrolytic copper foil. Using this extracted data, in order to calculate the number density of MoO _3, a scattering cross section was obtained from scattered X-rays, and fitting was performed. The measured X-ray scattering intensity I (q) and the scattering cross section dΣ / dΩ (q) are in the relationship of equation (2).

Φ０はダイレクトビームの強度、ηは検出器による補正項、Ｓは照射面積、Ｔは透過率、Ｄは厚さである。基本的にはΦ０、η、Ｓは一定なのでΦ０・η・Ｓ＝Ａ＝ｃｏｎｓｔとして装置固有の値とする。

Φ0 is the intensity of the direct beam, η is the correction term by the detector, S is the irradiation area, T is the transmittance, and D is the thickness. Since Φ0, η, and S are basically constant, Φ0 · η · S = A = const is set to a value unique to the apparatus.

  Regarding A, glassy carbon measured with an apparatus that previously determined Φ0, η, and S was also measured with SPring-8, BL19B2, and A was calculated. Symbols S, C, and N in Formula- (2) are abbreviations for Sample, Cell, and Noise, respectively. In this application, Sample is an electrolytic copper alloy foil, and Cell is a pure copper foil. When the scattering cross section is obtained from Equation- (2), Equation- (3) is obtained.

一方で散乱断面積は式−（４）で表される。

On the other hand, the scattering cross section is expressed by the formula-(4).

ｄΣ／ｄΩ（ｑ）は散乱断面積、Δρ２は原子散乱因子、ｄＮは粒子数密度、Ｖは粒子体積、Ｆは粒子の形状因子、Ｎ（ｒ）は粒径分布関数である。ＴＥＭ観察の結果から、粒子の形状因子は球体とした（式−（５））。

dΣ / dΩ (q) is a scattering cross section, Δρ2 is an atomic scattering factor, dN is a particle number density, V is a particle volume, F is a particle shape factor, and N (r) is a particle size distribution function. From the result of TEM observation, the shape factor of the particle was a sphere (formula- (5)).

散乱Ｘ線強度から求めた散乱断面積：ｄΣ／ｄΩ（ｑ）を変数ｑで式−（３）を用いてＦｉｔｔｉｎｇを行った。その結果、平均粒子径（半径）が解析的に求められた。

Fitting was performed using the equation-(3) with the scattering cross section obtained from the scattered X-ray intensity: dΣ / dΩ (q) as a variable q. As a result, the average particle diameter (radius) was analytically determined.

Battery Performance Test Next, a lithium ion secondary battery was prepared using the electrolytic copper foil produced in the example as a current collector, and a cycle life test was performed.
Powdered Si alloy-based active material (average particle size 0.1 μm to 10 μm) is mixed in a ratio (weight ratio) of 85 and binder (polyimide) at 15 (weight ratio), and dispersed in N-methylpyrrolidone (solvent). A slurry was obtained.
Subsequently, this slurry was applied to both surfaces of the prepared electrolytic copper foil having a thickness of 12 μm, dried and compression-formed with a roller press, and then sintered at 300 ° C. for 1 hour in a nitrogen atmosphere to obtain a negative electrode. In this negative electrode, the negative electrode mixture after molding had the same film thickness of 20 μm on both sides.

Creation of Lithium Ion Secondary Battery A three-electrode cell for evaluation was constructed with the following configuration in a glove box under an argon atmosphere.
Negative electrode: Si alloy negative electrode prepared above Counter electrode, reference electrode: Lithium foil Electrolytic solution: 1 mol / L LiPF ₆ / EC + DEC (3: 7 vol%)

The constructed cell was taken out from the box into the atmosphere, and charge / discharge measurement was performed in an atmosphere at 25 ° C.
Charging was performed at a constant current up to 0.02 V with respect to the standard unipolar potential of Li, and thereafter, charging was terminated when the current decreased by 0.05 C at CV (while being at a constant potential). C indicates a charge / discharge rate. Discharging was carried out at a constant current up to 1.5 V (based on Li) at 0.1 C. Charging / discharging was repeated with the same current equivalent to 0.1 C.
As an evaluation of the charge / discharge performance, the number of cycles until the discharge capacity reaches 70% of the discharge capacity of the first cycle is measured, and this is regarded as the cycle life, and it is judged that an electrode having a cycle life of 100 times or more can be used practically. , Passed level. Tables 1 and 2 show the cycle life of the electrodes manufactured under each condition. An electrode having a cycle life of less than 100 times was rejected, 100 times to less than 120 times was a good range, and 120 times or more was an optimum range.
Further, as an evaluation of the charge / discharge performance, the battery was disassembled after 100 cycles of charge / discharge, and the deformation and fracture of the foil were observed. The results are shown in Tables 1 and 2 as the deformation of the foil. Those with no deformation such as wrinkles were marked with ◯, and those with wrinkles and other deformation were rejected and marked with ×.
The content of Ti, Mo, V, Bi, Te of at least one of Ti, Mo, V, Bi, Te is preferably 0.0001 wt% or more, particularly 0.001-1.320 wt. % Is preferred. Outside this range, wrinkles were observed after the charge / discharge test.

As shown in Table 1, when the amount of Ti, Mo, V, Bi, Te in the electrolytic bath is increased, the amount of Ti, Mo, V, Bi, Te incorporated into the foil tends to increase. . Looking at the tensile strength at room temperature after heat treatment at 300 ° C. for 1 hour, all foils have excellent heat resistance of 450 MPa or more.
Under conditions where the amount of Ti, Mo, V, Bi, and Te incorporated is 0.001 wt% or more, the tensile strength at normal temperature after heat treatment at 300 ° C. for 1 hour is 460 MPa or more, which is particularly excellent in heat resistance.
However, in a foil having a Ti, Mo, V, Bi, and Te uptake of more than 1.320 wt%, the conductivity tends to be as low as less than 70% IACS, but practically 60% IACS or more. There is no hindrance, and in the case of Ti, Mo, V, Bi, Te uptake amount less than 0.001 wt%, the tensile strength at room temperature after heat treatment at 300 ° C. for 1 hour is slightly lower than 460 MPa. Is stronger than 450 MPa and practically has no problem, the amount of Ti, Mo, V, Bi, Te incorporated in the foil is 0.0001 wt% or more, preferably 0.001 to 1.320 wt. %, More preferably 0.001-1.000 wt%.

As confirmed in the above Example, according to the present invention, the tensile strength at room temperature is 650 MPa or more, the tensile strength measured at room temperature after heat treatment at 300 ° C. × 1 hour is 450 MPa or more, and the conductivity is 60% IACS or more. An electrolytic copper foil could be created.
Moreover, this invention is an electrolytic copper foil excellent in mechanical strength, and can be used suitably also in the use in the printed wiring board field bonded with a polyimide film.
Furthermore, the present invention is a lithium ion secondary battery using a Si or Sn alloy-based active material, and adheres between the current collector (copper foil) and the active material against the large expansion and contraction of the Si or Sn alloy-based active material. It is an excellent electrolytic copper foil that can retain its properties with a polyimide binder, has battery characteristics of 100 cycles or more of charge and discharge, and does not deform as a current collector (copper foil).

Table 2 shows the evaluation results of Comparative Examples 1-5.
In Comparative Example 1, the foil was made with an electrolytic solution to which ethylenethiourea and Mo were added. However, since the amount of Mo added was small, Mo could not be taken into the foil. Accordingly, the mechanical strength in the normal state is large, but the mechanical strength is significantly lowered after the heat treatment at 300 ° C. for 1 hour.

Comparative Examples 2 and 3 are foils made with a composition to which glue is added as an organic additive.
This copper foil has a low mechanical strength in a normal state, and the mechanical strength is remarkably lowered to 250 MPa or less after heat treatment at 300 ° C. for 1 hour. The measurement result of the amount of Mo in the copper foil was less than 0.0001 wt%, which is the lower limit of detection.
Although glue is added to the electrolyte, glue does not have [= S], so glue can preferentially adsorb on copper rather than chloride ions to form an organic molecule adsorption layer on copper. It is considered that Mo oxide was not adsorbed on copper, Mo was not taken into the foil, and the electrolytic Cu-Mo foil was not formed.

In Comparative Examples 4 and 5, as an example that does not exist as an oxide in an electrolyte solution having a pH of 4 or lower and dissolves as ions, Fe and Ni are added to form foil. However, Fe and Ni are not taken into the foil, and thus the mechanical strength in the normal state is large, but the mechanical strength is significantly lowered after the heat treatment at 300 ° C. × 1 hour.
Furthermore, in the lithium ion secondary battery using the electrolytic copper foil of Comparative Examples 1 to 5 as a current collector, the current collector (copper foil) is deformed in 100 cycles or less of charge and discharge, and the battery is required for practical use. There is a problem with the characteristics.

According to this invention, the negative electrode collector for secondary batteries using the electrolytic copper foil in any one of the above is provided.
Moreover, according to the present invention, the electrolytic copper foil according to any one of the above is used as a negative electrode current collector for a secondary battery, and on its surface, silicon, germanium, tin, an alloy compound thereof or a main component thereof. An electrode for a secondary battery is provided in which an active material is deposited.

According to the present invention, a secondary battery using the secondary battery electrode is provided.
According to the present invention, a sulfuric acid-copper sulfate-based electrolytic solution is added with at least one kind of metal salt existing as an oxide in an acidic solution having a pH of 4 or less, chloride ions as an additive. As a result of the analysis, a method for producing an electrolytic copper foil is provided, which comprises an electrolytic copper foil containing at least one kind of metal present as an oxide in an acidic solution having a pH of 4 or less, and the balance being copper.

  Further, according to the present invention, the metal present as an oxide in an acidic solution having a pH of 4 or less is contained at 0.0001 wt% or more, the tensile strength at room temperature is 650 MPa or more, and measured at room temperature after heat treatment at 300 ° C. for 1 hour. A method for producing a copper foil having a tensile strength of 450 MPa or more and an electrical conductivity of 60% IACS or more, wherein the copper foil is oxidized in an acidic solution having a pH of 4 or less as an additive to a copper sulfate electrolyte. Copper to be foil-formed with a copper sulfate-based electrolyte containing 100 to 10,000 mg / L of a metal present as a product, 1 to 20 mg / L of a thiourea compound, and 1 to 100 mg / L of a chloride ion A method of manufacturing a foil is provided.

DESCRIPTION OF SYMBOLS 13 ... X-ray source 14 ... Incident X-ray 15 ... Shutter 17 ... Monochromator 19 ... 1st pinhole 21 ... 2nd pinhole 23 ... Attenuator 25 ... Third pinhole 27 ... Sample 29 ... Transmission X-ray 31 ... scattered X-ray 33 ... Beam stopper 35 ... Detector

Claims (6)

The untreated copper foil contains a metal present as an oxide or an oxide thereof in an acidic solution having a pH of 4 or less, and the content of the metal or the content of the metal constituting the oxide is 0.0001 to 1 .320 % by mass and containing 0.005 to 0.04% by mass of chlorine. The metal constituting the metal or its oxide is at least one selected from titanium (Ti), molybdenum (Mo), vanadium (V), bismuth (Bi), and tellurium (Te).
The electrolytic copper foil according to claim 1 . The tensile strength at room temperature is 650 MPa or more,
Tensile strength measured at room temperature after heat treatment at 300 ° C. for 1 hour is 450 MPa or more
The electrolytic copper foil of Claim 1 or 2 . Conductivity at room temperature is 60% IACS or higher
The electrolytic copper foil in any one of Claims 1-3 . The electrode for lithium ion secondary batteries which uses the electrolytic copper foil in any one of Claims 1-4 as a collector. A lithium ion secondary battery using the battery electrode according to claim 5 as a negative electrode.

Images