JP5810249B1 - Electrolytic copper foil, negative electrode for lithium ion secondary battery, lithium ion secondary battery, printed wiring board, and electromagnetic shielding material - Google Patents

Abstract

Provided an electrolytic copper foil that is excellent in handling at the time of manufacturing a secondary battery and does not decrease the tensile strength even when heated at 150 ° C. for 1 hour, and further increased the cycle life by using the electrolytic copper foil as a current collector. A negative electrode for a lithium ion secondary battery and a lithium ion secondary battery incorporating the electrode are provided. Tensile surface roughness Rz of 2.0 μm or less, gloss Gs (60?) Of 40 to 150, dynamic friction coefficient of 0.11 to 0.29, measured at room temperature after heating at 150 ° C. for 1 hour An electrolytic copper foil having a strength of 300 MPa or more and a lithium ion secondary battery using the electrolytic copper foil as a current collector are provided.

Description

The present invention relates to an electrolytic copper foil, a negative electrode for a lithium (Li) ion secondary battery and a lithium ion secondary battery using the same.
Moreover, this invention relates to the printed wiring board and electromagnetic wave shielding material which used this invention electrolytic copper foil.

A lithium ion secondary battery is composed of, for example, a positive electrode, a negative electrode having a negative electrode active material layer formed on the surface of a negative electrode current collector, and a non-aqueous electrolyte. It is used.
As the negative electrode of the lithium ion secondary battery, a so-called “untreated copper foil” manufactured by electrolysis is subjected to rust prevention treatment, and the negative electrode active material layer is formed on the surface of the copper foil (negative electrode current collector). It is formed by applying, drying, and pressing carbon particles or the like.
In order for the lithium ion secondary battery to obtain sufficient battery characteristics, the distance between the active material particles and the distance between the active material and the current collector are reduced, and the shape of the current collector is deformed along the shape of the active material surface. This is very important. When the current collector is deformed along the shape of the active material surface, the contact between the active material and the current collector is further improved, the electric conductivity is further increased, and desirable battery characteristics can be obtained. On the other hand, when the current collector does not deform along the shape of the active material surface, the contact portion between the active material and the current collector is reduced, the electrical conductivity is reduced, and desirable battery characteristics cannot be obtained.

Moreover, when the unevenness | corrugation of the collector surface is large, there are few contact points of an active material and a collector, and contact resistance becomes high. Such an electrode having a large contact resistance, when repeated charging and discharging, due to stress due to expansion and contraction accompanying charging and discharging of the active material, dissolution of the binder as an adhesive in the electrolytic solution, and the like, As the distance increases, some active materials become electrical conductivity that cannot be used for charging and discharging, resulting in capacity degradation. Therefore, a copper foil having a tensile strength equal to or higher than a predetermined value and smoother on both sides is preferably used for the negative electrode current collector (Patent Document 1).
However, when an electrolytic copper foil with smoother surfaces is used as the negative electrode current collector of a lithium ion secondary battery, the smooth copper foil slips on the transport roll in the active material coating line in the battery manufacturing process. There is a risk that the slip may cause wrinkles in the copper foil (current collector), or a defect may occur in the active material coating process.
In addition, the volume of the active material that accompanies insertion and extraction of lithium during charge and discharge may make it difficult to maintain a good adhesion between the current collector and the active material. Occurs and the cycle characteristics deteriorate.
As such a countermeasure, it is necessary to set the tensile strength of the current collector to a predetermined value or more.

Also, recently, in printed wiring boards such as rigid printed wiring boards and flexible printed wiring boards, printed wiring boards that have higher adhesion strength between the copper foil and the film and have excellent high frequency characteristics required for circuit boards have been developed. It is requested. In addition, there is a demand for copper foil that is thin and strong, and that is less likely to cause foil breakage or wrinkles, particularly in the manufacturing process of flexible printed wiring boards.
In addition, a copper foil that maintains high strength is required even after a thermal history when manufacturing a printed wiring board.

Japanese Patent No. 3742144

The present invention provides an electrolytic copper foil that is smooth on both sides, excellent in tensile strength, and does not decrease in tensile strength at room temperature even when heated at 150 ° C. for 1 hour, and lithium using the electrolytic copper foil as a current collector. An object is to provide a negative electrode for an ion secondary battery and a lithium ion secondary battery.
Moreover, in addition to the higher adhesion strength between copper foil and film, high frequency characteristics, and strength of thin foil required for printed wiring boards such as rigid printed wiring boards and flexible printed wiring boards, especially flexible printed wiring An object of the present invention is to provide an electrolytic copper foil that is less prone to foil breakage, wrinkles, and the like in the plate manufacturing process.
Moreover, it aims at providing the electrolytic copper foil which maintains high intensity | strength even if it passes through the thermal history concerning the time of manufacturing a printed wiring board.
Furthermore, it aims at providing the electrolytic copper foil for electromagnetic wave shielding materials which is excellent in the effect of an electromagnetic wave shield, and is hard to produce foil cutting, a wrinkle, etc. in a manufacturing process.

  The electrolytic copper foil of the present invention has a 10-point average surface roughness Rz of 2.0 μm or less and a glossiness Gs (60 °) of 40 or more on at least one of the matte surface (M surface) and shiny surface (S surface). 150 or less, the dynamic friction coefficient is 0.11 or more and 0.29 or less, and the tensile strength measured at room temperature after heating at 150 ° C. for 1 hour is 300 MPa or more.

  The electrolytic copper foil of the present invention preferably has a tensile strength of 400 MPa or more measured at room temperature after heat treatment at 150 ° C. for 1 hour.

The negative electrode for a lithium ion secondary battery of the present invention uses the electrolytic copper foil of the present invention as a current collector.
Moreover, the lithium ion secondary battery of this invention is a secondary battery incorporating the negative electrode which used the said this invention electrolytic copper foil as a collector.
Moreover, the printed wiring board of this invention uses the said electrolytic copper foil as a conductor.
Furthermore, the electromagnetic shielding material of the present invention uses the electrolytic copper foil as a shielding material.

In the present invention, at least one of the matte surface (M surface) and the shiny surface (S surface) has a 10-point average surface roughness Rz of 2.0 μm or less, a glossiness Gs (60 °) of 40 to 150, dynamic friction It is possible to provide an electrolytic copper foil having a coefficient of 0.11 or more and 0.29 or less, and a tensile strength measured at room temperature after heating the copper foil at 150 ° C. for 1 hour is 300 MPa or more. it can.
The present invention provides a negative electrode for a lithium ion secondary battery with improved cycle characteristics by using an electrolytic copper foil having a surface roughness Rz of 2.0 μm or less and a glossiness Gs (60 °) of 40 or more as a current collector. Can be provided.
In addition, the present invention uses the electrolytic copper foil having a surface roughness Rz of 2.0 μm or less and a glossiness Gs (60 °) of 40 or more as a current collector, so that the contact between the active material and the current collector is good. Thus, a secondary battery with high electrical conductivity and good cycle life can be provided.
In addition, the electrolytic copper foil constituting the current collector has a tensile strength of 300 MPa or more measured at room temperature after heating at 150 ° C. for 1 hour, so that it can withstand stress due to active material volume expansion and contraction during charge and discharge. And a secondary battery having a good cycle life can be provided.

Furthermore, by attaching an electrolytic copper foil having a surface roughness Rz of 2.0 μm or less and a glossiness Gs (60 °) of 40 or more to an insulating film, a finer unevenness existing on the surface of the copper foil allows higher copper. A printed wiring board (for example, a rigid printed wiring board, a flexible printed wiring board, etc.) excellent in high frequency characteristics required for a circuit board while having adhesion strength between the foil and the insulating film can be provided.
In addition, the electrolytic copper foil of the present invention is strong even when it is a thin foil, and it can be preferably used, particularly in the process of manufacturing a flexible printed wiring board, in which foil breakage, wrinkles and the like are unlikely to occur. Moreover, high intensity | strength can be maintained even if it passes through the thermal history concerning the time of manufacturing a printed wiring board because the tensile strength in the normal temperature after 150 degreeC and 1 hour heating of copper foil is 300 Mpa or more.
The electrolytic copper foil of the present invention has an excellent effect as an electromagnetic shielding material.
Moreover, in any application, the electrolytic copper foil of the present invention has a fine surface with fineness Gs (60 °) of the copper foil of 150 or less and a dynamic friction coefficient of 0.11 or more and 0.29 or less. The unevenness becomes anti-slip on the transport roll, and the foil is prevented from slipping on the roll, so that the handling property is good.

[Configuration of electrolytic copper foil]
One embodiment of the present invention will be described with respect to an electrolytic copper foil constituting a current collector for a lithium ion secondary battery. However, the electrolytic copper foil of the present invention is not used only for a current collector for a lithium ion secondary battery, and is appropriately used for other purposes as long as the gist of the printed wiring board, the electromagnetic conductor, etc. does not change its gist. Can be used.
The electrolytic copper foil for a lithium ion secondary battery negative electrode current collector of the present embodiment has a tensile strength at room temperature of 300 MPa or more, particularly preferably 400 MPa or more after being subjected to a heat treatment at 150 ° C. for 1 hour. Thus, it is possible to withstand the stress due to the volume expansion and contraction of the active material, and to provide a secondary battery having a good cycle life.

For example, the electrolytic copper foil for a lithium ion secondary battery current collector of the present embodiment is provided with a rust-proofing layer on at least the surface on the side where the active material layer is provided on the electrolytic copper foil.
The antirust treatment layer is, for example, a chromate treatment layer, or a nickel or Ni alloy plating layer, a Co or Co alloy plating layer, a Zn or Zn alloy plating layer, a Sn or Sn alloy plating layer, or a chromate treatment on the above various plating layers. It is an inorganic rust preventive treatment such as one provided with a layer, or an organic rust preventive treatment layer such as benzotriazole.
Furthermore, a silane coupling agent treatment layer or the like may be formed.
The inorganic rust-proofing treatment, organic rust-proofing treatment, and silane coupling agent treatment increase the adhesion strength with the active material and prevent the charge / discharge cycle efficiency of the battery from decreasing.

  Further, for example, the electrolytic copper foil for the lithium ion secondary battery current collector of the present embodiment is subjected to a roughening treatment on the surface on which the active material layer of the electrolytic copper foil is provided, and the roughened treatment is applied to the surface subjected to the roughening treatment. A rust-proofing layer is provided, and if necessary, a silane coupling agent-treated layer is provided.

The electrolytic copper foil of the present embodiment has a 10-point average surface roughness Rz of 2.0 μm or less and a glossiness Gs (60 °) on at least one of the matte surface (M surface) and the shiny surface (S surface). It is 40 or more and 150 or less, and a dynamic friction coefficient is 0.11 or more and 0.29 or less.
Gs (60 °) represents the glossiness measured at a light projection / reception angle of 60 °.
The at least one surface is preferably a surface on the side where the active material layer is formed. When the active material is formed on both surfaces, it is preferable that the surface roughness Rz and the glossiness Gs (60 °) satisfy the above ranges for both surfaces.
The surface roughness Rz of the surface on which at least the active material layer of the electrolytic copper foil is formed is 2.0 μm or less. When the surface roughness is 2.0 μm or more, the surface of the electrolytic copper foil (current collector) has large irregularities, and the active material As a result, the number of contact points of the current collector is reduced, resulting in an electrode having a large contact resistance. Therefore, when charging / discharging is repeated, the distance between the current collector and the active material gradually increases due to stress due to expansion / contraction associated with charging / discharging of the active material and dissolution of the binder as an adhesive in the electrolyte. This is because there is a concern that the active material of the part may have electric conductivity that cannot be used for charging and discharging, resulting in deterioration of capacity, which is not preferable.

Moreover, the electrolytic copper foil of this embodiment makes glossiness Gs (60 degrees) 40-150, and makes a dynamic friction coefficient 0.11-0.29. When the surface roughness Rz of the copper foil is 2.0 μm or less and the glossiness Gs (60 °) is 40 or more, the contact between the active material and the current collector is improved, the electric conductivity is high, and the cycle is good. Life expectancy is obtained.
In addition, when the glossiness Gs (60 °) of the copper foil is 150 or less and the coefficient of dynamic friction is 0.11 or more and 0.29 or less, fine irregularities on the surface of the copper foil are produced in the active material coating line in the battery manufacturing process. It becomes slippery on a conveyance roll, it is suppressed that copper foil slips on a roll, a wrinkle does not generate | occur | produce in copper foil in a battery manufacturing line, and handling property becomes favorable. The fine irregularities also function as an anchor effect between the active material and the current collector, and are effective in improving the adhesion of the active material.
That is, the handling property is good when the glossiness Gs (60 °) is 150 or less and the dynamic friction coefficient is 0.11 or more and 0.29 or less, more preferably 0.15 or more and 0.25 or less, and the battery characteristics are glossiness Gs. (60 °) is 40 or more, and is good when the tensile strength at room temperature after heating at 150 ° C. for 1 hour is 300 MPa or more.

  In addition, when the electrolytic copper foil of the present embodiment is applied to, for example, a printed wiring board for high frequency, the resistance value of the surface region increases as the surface roughness Rz increases due to the skin effect that increases as the frequency increases, and transmission loss increases. In order to prevent the increase in transmission time and transmission delay time, the ten-point surface roughness Rz is preferably 2.0 μm or less.

[Method for producing electrolytic copper foil]
The electrolytic copper foil for the negative electrode current collector of the lithium ion secondary battery according to the present embodiment includes, for example, an insoluble anode made of titanium coated with a white metal element or an oxide element thereof using a sulfuric acid-copper sulfate aqueous solution as an electrolyte and the anode Copper is deposited on the surface of the cathode drum by supplying a direct current between both electrodes while supplying the electrolyte between the cathode cathode and a titanium cathode drum provided opposite to the cathode drum and rotating the cathode drum at a constant speed. The deposited copper is peeled off from the surface of the cathode drum and is continuously wound up.

The electrolytic copper foil for a lithium ion secondary battery negative electrode current collector of the present embodiment can be produced, for example, by performing an electrolytic treatment in a sulfuric acid-copper sulfate electrolytic plating solution.
As a copper concentration of a sulfuric acid-copper sulfate electroplating solution, the range of 40-120 g / L is used, for example, Preferably the range of 60-100 g / L is used.
Moreover, as a sulfuric acid concentration of a sulfuric acid-copper sulfate electroplating solution, the range of 40-60 g / L is used.
The chlorine concentration in the sulfuric acid-copper sulfate electroplating solution is in the range of 5-25 ppm.
Moreover, about an additive, both the organic additives A and B shown below are used.

The organic additive A is a thiourea compound and is a thiourea compound having 4 or more carbon atoms.
Examples of the organic additive A include N, N′-diethylthiourea (C ₅ H ₁₂ N ₂ S), tetramethylthiourea (C ₅ H ₁₂ N ₂ S), N, N′-allylthiourea (C ₄ H _8). Water-soluble thiourea derivatives such as N ₂ S) can be used.

The organic additive B includes, for example, glue, gelatin, polyethylene glycol, polypropylene glycol, starch, high molecular polysaccharides such as cellulose water-soluble polymers (carboxyl methyl cellulose, hydroxyethyl cellulose, etc.), polyethylene imine, polyallyl, polyallylamine, One or more additives selected from water-soluble polymer compounds such as polyacrylamide can be used.
In addition to organic additive A, organic additive B is further added, and foil formation is performed under specific electrolysis conditions, so that the strength is high, the surface roughness Rz is 2.0 μm or less, and the glossiness Gs (60 °) is 40. An electrolytic copper foil having a dynamic friction coefficient of 0.11 to 0.29, more preferably 0.15 to 0.25, can be produced.

For the produced electrolytic copper foil (untreated copper foil), for example, chromate treatment, Ni or Ni alloy plating, Co or Co alloy plating, Zn or Zn alloy plating, Sn or Sn alloy plating, the above various plating layers Further, an inorganic rust prevention treatment such as a chromate treatment or an organic rust prevention treatment such as benzotriazole.
Furthermore, for example, a silane coupling agent treatment or the like is performed to obtain an electrolytic copper foil for a negative electrode current collector of a lithium ion secondary battery.
The inorganic rust prevention treatment, organic rust prevention treatment, and silane coupling agent treatment increase the adhesion strength with the active material and prevent the charge / discharge cycle efficiency of the battery from being lowered.

Moreover, before performing said rust prevention process, it is also possible to perform a roughening process, for example to the electrolytic copper foil surface. As the roughening treatment, for example, a plating method or an etching method can be suitably employed.
The plating method is a method of roughening the surface by forming a thin film layer having irregularities on the surface of the untreated electrolytic copper foil. As the plating method, an electrolytic plating method and an electroless plating method can be employed. As the roughening by the plating method, a method of forming a plating film mainly composed of copper such as copper or copper alloy on the surface of the untreated electrolytic copper foil is preferable.

  As the roughening by the etching method, for example, a method by physical etching or chemical etching is suitable. For physical etching, there is a method of etching by sandblasting or the like, and for chemical etching, many liquids containing an inorganic or organic acid, an oxidizing agent, and an additive have been proposed.

[Configuration and production method of lithium ion secondary battery using current collector for lithium ion secondary battery]
The negative electrode of the lithium ion secondary battery of the present embodiment uses the electrolytic copper foil for the negative electrode current collector of the lithium ion secondary battery of the present embodiment as a current collector, and the surface of the current collector such as the rust preventive treatment layer In this configuration, an active material layer is formed on the treated surface.

  For example, the active material layer is obtained by applying a slurry obtained by kneading an active material, a binder, and a solvent to a negative electrode current collector, drying, and pressing.

  The active material layer in the present embodiment is a material that occludes / releases lithium, and is preferably an active material that occludes lithium by alloying. Examples of such an active material include group 14 elements such as carbon, silicon, germanium, and tin.

  In the present embodiment, the current collector is preferably as thin as 4 to 10 μm, and the active material layer is formed on one side or both sides of the current collector. When the active material is applied only to the glossy surface of the copper foil formed from the drum having a surface roughness Rz of 1.0 μm or more and 2.0 μm or less, the surface on which the active material is applied is smooth and the adhesion with the active material is It was good. If the thickness of the current collector is 4 μm or less, the foil is likely to break, and the production is difficult. If the current collector is thicker than 10 μm, it is not preferable from the viewpoint of weight reduction and high energy density of the battery. In addition, when the coefficient of dynamic friction is 0.11 or less, the surface is too smooth, so that it easily slips on the surface of the transport roll in the copper foil manufacturing process and the battery manufacturing process, and is easily wrinkled. Therefore, a collector (copper foil) that has good handling properties and is effective in reducing the weight and increasing the energy density of the battery by setting the thickness of the copper foil to 4 to 10 μm and the dynamic friction coefficient in the range of 0.11 to 0.29. )

When forming a carbon-based negative electrode active material layer, a paste made of carbon as a negative electrode active material, polyvinylidene fluoride resin as a binder, and N-methylpyrrolidone as a solvent is prepared, and a current collector (copper foil) Apply to one or both sides and dry.
For example, lithium may be occluded or added to the active material layer in this embodiment in advance. Lithium may be added when forming the active material layer. That is, lithium is contained in the active material layer by forming an active material layer containing lithium. Further, after forming the active material layer, lithium may be occluded or added to the active material layer. Examples of a method for inserting or adding lithium into the active material layer include a method for electrochemically inserting or adding lithium.

  Moreover, the lithium ion secondary battery of this embodiment is a lithium ion secondary battery provided with a positive electrode and a negative electrode, Comprising: A negative electrode is comprised by the lithium ion secondary battery negative electrode of said this embodiment.

  When the electrolytic copper foil of the present embodiment is applied to, for example, a printed wiring board for high frequency, the resistance value of the surface region increases when the surface roughness Rz is large due to the skin effect that increases as the frequency becomes high, and the transmission loss increases. In order to prevent an increase in the transmission delay time, the ten-point surface roughness Rz is preferably 2.0 μm or less.

[Configuration of printed wiring board]
The electrolytic copper foil of the present invention is a printed wiring board such as a rigid printed wiring board or a flexible printed wiring board (in this specification, the rigid printed wiring board, the flexible printed wiring board, etc. may be collectively referred to as a printed wiring board). It can be used in various fields such as electromagnetic shielding materials.
Recent printed wiring boards are usually divided into two types. One is a three-layer printed wiring board in which a copper foil is attached to an insulating film (polyimide, polyester, etc.) with an adhesive resin and etched to give a pattern. On the other hand, another type is a two-layer printed wiring board in which an insulating film (polyimide, liquid crystal polymer, etc.) and a copper foil are directly laminated without using an adhesive.
The electrolytic copper foil of the present invention is laminated with an insulating film as a conductor of these printed wiring boards.

The main uses of printed wiring boards are for flat panel displays such as liquid crystal displays and plasma displays, or for internal wiring of cameras, AV equipment, personal computers, computer terminal equipment, HDDs, mobile phones, car electronics equipment, and the like. Since these wirings are used in places where they are bent or attached to equipment or repeatedly bent, one of the important characteristics of copper foil for printed wiring boards is that they are durable and flexible. It is a characteristic.
The printed wiring board according to the present invention has a surface roughness Rz of 2.0 μm or less and a glossy Gs (60 °) of 40 or more. Due to the unevenness, a printed wiring board having excellent high-frequency characteristics required for a circuit board can be obtained while having higher adhesion strength between the copper foil and the insulating film.
In addition, the copper foil laminated with the insulating film has a tensile strength of 300 MPa or more measured at room temperature after heating at 150 ° C. for 1 hour, so that even a thin foil has strength, especially in the manufacturing process of a flexible printed wiring board. It is difficult for wrinkles and wrinkles to occur.
In addition, the tensile strength at room temperature after heating at 150 ° C. for 1 hour of the copper foil that laminates the insulating film is 300 MPa or more, so that a high strength is maintained even after passing through a heat history when manufacturing a printed wiring board. be able to.

The excellent characteristics of the electrolytic copper foil of the present invention are excellent in the electromagnetic shielding effect even when the electrolytic copper foil of the present invention is applied to an electromagnetic shielding, and becomes an excellent electromagnetic shielding material by being bonded to an insulating substrate. .
Moreover, in any application, the electrolytic copper foil of the present invention has a glossiness Gs (60 °) of the copper foil of 150 or less and a dynamic friction coefficient of 0.11 or more and 0.29 or less. Becomes anti-slip on the transport roll and suppresses the foil from slipping on the roll, so that the handling property is improved.

  Hereinafter, the present invention will be described in more detail based on the examples in Table 1. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented without departing from the scope of the present invention. Is possible.

[Manufacture of untreated copper foil]
Examples 1-12
Adjust the copper concentration to 65 g / L, the sulfuric acid concentration to 45 g / L, and the chloride ion concentration to 25 ppm, and use the electrolyte solution to which the additives A and B shown in Table 1 are added, and the anode (anode) is coated with a noble metal oxide An untreated copper foil having a thickness of 10 μm was produced by an electrolytic foil method under the conditions of a current density of 35 A / dm ² and a bath temperature of 50 ° C. using a titanium rotating drum as a titanium electrode and a cathode (cathode).
The untreated copper foil is preferably produced at a current density of 35 A / dm ² or less. If the current density is made larger than 35 A / dm ² and the foil is made, the smoothness of the copper foil surface is lowered, and it may be difficult to make the dynamic friction coefficient 0.29 or less.

Comparative Examples 1-8
About Comparative Examples 1-8, the untreated copper foil was manufactured so that thickness might be set to 10 micrometers with the same installation as an Example by the electrolyte solution of the composition shown in Table 2, and electrolysis conditions.

[Measurement of tensile strength and elongation of electrolytic copper foil]
The tensile strength (MPa) and elongation rate (%) at normal temperature of each electrolytic copper foil of Examples 1 to 12 and Comparative Examples 1 to 8 were measured. The results are shown in Table 3.
The tensile strength (MPa) and elongation (%) were measured at room temperature even after heat treatment at 150 ° C. for 1 hour, and the results are also shown in Table 3.
The tensile strength and elongation are values measured at a tensile test speed of 50 mm / min using a tensile tester (Instron type 1122).
In this embodiment, “normal temperature” represents a normal temperature before the heat treatment of 150 ° C. for 1 hour as described above, typically 20 ° C.

[Measurement of surface roughness Rz]
Ten-point average surface roughness Rz (μm) of the mat surface of each of the electrolytic copper foils of Examples 1 to 12 and Comparative Examples 1 to 8 was measured. The measurement was performed by the method defined in JIS B 0601-1994), and the results are shown in Table 3.

[Measurement of dynamic friction coefficient of electrolytic copper foil]
The dynamic friction coefficients of the electrolytic copper foils of Examples 1 to 12 and Comparative Examples 1 to 8 were measured using a surface property measuring machine (HEIDON 14FW manufactured by Shinto Kagaku Co., Ltd.). The measurement conditions were as follows: a 10 mm diameter steel ball was used for the slider, the sliding speed was 100 mm / min, and the sliding distance was 10 mm once per way. The results are shown in Table 3. Table 3 shows the measurement results for the matte surface, but almost the same results were obtained for the shiny surface.

[Measurement of gloss of electrolytic copper foil]
The glossiness Gs (60 °) of the mat surface of each of the electrolytic copper foils of Examples 1 to 12 and Comparative Examples 1 to 8 was measured using a glossmeter (VG2000 manufactured by Nippon Denshoku Industries Co., Ltd.) at a light emitting / receiving angle of 60 °. Measured at The results are shown in Table 3.

[Chromate treatment]
The surface of each electrolytic copper foil of Examples 1 to 12 and Comparative Examples 1 to 8 was subjected to chromate treatment to form a rust preventive treatment layer to obtain a current collector.
The conditions for the chromate treatment of the copper foil surface are as follows.
Chromate treatment conditions:
Potassium dichromate 1-10g / L
Immersion treatment time 2 to 20 seconds

[Evaluation of battery characteristics]
1. Production of positive electrode 90% by weight of LiCoO ₂ powder, 7% by weight of graphite powder and 3% by weight of polyvinylidene fluoride powder were mixed and a solution prepared by dissolving N-methylpyrrolidone in ethanol was added and kneaded to prepare a positive electrode agent paste. . The paste was evenly applied to an aluminum foil having a thickness of 15 μm, dried in a nitrogen atmosphere to evaporate ethanol, and then rolled to produce a sheet having an overall thickness of 100 μm. The sheet was cut into a width of 43 mm and a length of 290 mm, and then an aluminum foil lead terminal was attached to one end thereof by ultrasonic welding to form a positive electrode.

2. Production of negative electrode:
90% by weight of natural graphite powder (average particle size: 10 μm) and 10% by weight of polyvinylidene fluoride powder were mixed, and a solution in which N-methylpyrrolidone was dissolved in ethanol was added and kneaded to prepare a paste. Next, this paste was applied to both surfaces of each of the copper foils of Examples and Comparative Examples. The coated copper foil was dried in a nitrogen atmosphere to evaporate ethanol, and then rolled to form a sheet having an overall thickness of 100 μm. This sheet was cut into a width of 43 mm and a length of 285 mm, and then a nickel foil lead terminal was attached to one end thereof by ultrasonic welding to form a negative electrode.

3. Battery fabrication:
The whole was wound with a 25 μm thick polypropylene separator sandwiched between the positive electrode and negative electrode manufactured as described above, and this was accommodated in a nickel-plated battery can, and the lead terminal of the negative electrode was spotted on the bottom of the can Welded. Next, place the top cover of the insulating material, insert the gasket, and connect the lead terminal of the positive electrode and the aluminum safety valve by ultrasonic welding to connect the non-aqueous electrolyte consisting of propylene carbonate, diethyl carbonate and ethylene carbonate in the battery can. Then, a lid was attached to the safety valve, and a sealed structure type lithium ion secondary battery having an outer shape of 14 mm and a height of 50 mm was assembled.

4). Measurement of battery characteristics The above batteries were subjected to a charge / discharge cycle test in which a cycle of charging to 4.2 V at a charging current of 50 mA and discharging to 2.5 V at 50 mA was taken as one cycle. Table 3 shows the battery capacity and cycle life at the first charge. The cycle life is the number of cycles when the discharge capacity of the battery is below 300 mAh. The results are shown in Table 3.
5. Evaluation of good handling A foil that can be smoothly transported without any foil slip on the transport roll and without being caught on the transport roll in the coating process of 1000 m foil in the active material coating line. The results are shown in Table 3. The results are shown in Table 3, where ◎ indicates that the handleability is good and 箔 indicates that the slip occurs or the foil is caught on the roll and the conveyance stops, and the handleability is poor.
In addition, although some troubles occurred in the transportation, those that did not cause a problem in the coating of the active material were marked with a circle.

  From Table 3, Examples 1 to 12 have an excellent tensile strength of 400 cycles or more because the tensile strength at room temperature after heating at 150 ° C. for 1 hour is 300 MPa or more and the glossiness Gs (60 °) is 40% or more. Showed good battery characteristics. Furthermore, the coefficient of dynamic friction was not less than 0.11 and not more than 0.29, slippage with a roll during line production was suppressed, and handling properties were good.

However, the copper foil of Comparative Example 1 has a tensile strength at room temperature after heating of less than 300 MPa, Rz on the mat surface side is as large as 2.0 or more, and gloss (60 °) is very low as 40 or less. Since the contact with the active material is not good, the stress due to the expansion and contraction of the active material during charge / discharge cannot be endured, and the active material layer formed on the mat surface side is peeled off, resulting in a cycle life of 400 cycles or less. And it was very low. In addition, since the dynamic friction coefficient is as high as 0.33, the foil is caught on the transport roll and may be stopped, so that the handling property is not preferable.
Although the copper foil of Comparative Example 2 has a tensile strength after heating of 300 MPa or more, the Rz on the mat surface side is 2.0 or more and the glossiness is 40 or less. The contact property of the current collector was not so good, and the cycle life was 400 cycles or less. In addition, since the dynamic friction coefficient on the mat surface side was as high as 0.28, the handling property was a preferable result.
Moreover, the copper foils of Comparative Examples 3, 5, and 8 have a kinetic friction coefficient on the mat surface side of less than 0.11 and a glossiness Gs (60 °) of 150 or more. Since it slips and wrinkles occur, handling is difficult and the result is not preferable.
Comparative Example 4 showed a preferable cycle life because the tensile strength at room temperature after heating was 300 MPa or more, and the glossiness Gs (60 °) on the mat surface side was 40 or more. Since it was as low as 0.11 or less, a slip occurred during transportation, so that handling was not preferable.
In Comparative Example 6, the dynamic friction coefficient on the mat surface side is preferably 0.20 and the glossiness Gs (60 °) is preferably 143. However, since the tensile strength at normal temperature after heating is as low as 300 MPa or less, The cycle characteristics were poor due to the influence of the deformation of the foil that could not withstand the expansion and contraction of the material.
In Comparative Example 7, the glossiness Gs (60 °) on the mat surface side is as high as 40 or more, so the adhesion with the active material was good, but the strength after heating at 150 ° C. for 1 hour is 300 MPa or less. The cycle characteristics were poor due to the deformation of the foil caused by the expansion and contraction of the active material during charging and discharging. Furthermore, since the dynamic friction coefficient was as low as 0.11 or less and the glossiness Gs (60 °) was as high as 150 or more, the handling property was not preferable.

As described above, the electrolytic copper foil of the present invention has a tensile strength at room temperature after heating at 150 ° C. for 1 hour of 300 MPa or more, preferably 400 MPa or more, a surface roughness Rz of 2.0 μm or less, and a glossiness Gs (60 °) is 40 or more and 150 or less, and a dynamic friction coefficient is 0.11 or more and 0.29 or less, preferably 0.15 or more and 0.25 or less, and shows good lithium ion secondary battery characteristics. On the other hand, it is possible to provide an electrolytic copper foil that is difficult to slip on the production line and has good handleability during the production of the line.
Moreover, the electrolytic copper foil of the present invention has a tensile strength at room temperature of 150 MPa or higher after heating at 150 ° C. for 1 hour, can withstand stress due to volume expansion / contraction of the active material during charge / discharge, and has a good cycle life. A secondary battery is obtained.

Furthermore, the electrolytic copper foil of the present invention has a surface roughness Rz of 2.0 μm or less and a glossiness Gs (60 °) of 40 or more, so that the contact property between the active material and the current collector is good, and the electrical conductivity. And a good cycle life can be obtained.
Furthermore, the electrolytic copper foil of the present invention has a gloss Gs (60 °) of 150 or less and a dynamic friction coefficient of 0.11 or more and 0.29 or less. Is suppressed from slipping on the roll, and handling properties are improved.

  Moreover, the lithium ion secondary battery negative electrode of the present invention becomes a lithium ion secondary battery negative electrode with improved cycle characteristics by using the electrolytic copper foil of the present invention as a current collector, and the lithium ion secondary battery incorporating the electrode. The secondary battery is a battery having an excellent cycle life.

[Production and evaluation of printed wiring boards]
The electrolytic copper foil of Example 5 was bonded to a polyimide film to produce a three-layer printed wiring board, and the performance of the completed wiring board was evaluated.
(1) Adhesiveness between copper foil and film The adhesiveness between the copper foil and the film was such that the polyimide film digs into the fine irregularities present on the surface of the copper foil, and had satisfactory adhesive strength.
(2) High-frequency characteristics The high-frequency characteristics of the printed wiring board are that the roughness Rz of the copper foil surface is 2.0 μm or less, the glossiness Gs (60 °) is 40 or more, and the unevenness of the copper foil surface is fine. Therefore, it was satisfactory. (3) Strength of copper foil and generation of wrinkles Tensile strength of copper foil at room temperature is 662 MPa, and since it is 450 MPa or more, the strength of bonding with an insulating film is sufficient even with a thin foil. There was no occurrence of foil breakage or wrinkles in the process.
(4) Thermal history There is almost no change in strength due to the thermal history in the copper foil during heating when the copper foil and the insulating film are bonded together, and even after passing through the thermal history when manufacturing a printed wiring board, the strength is high. Maintained.

As described above, the present invention is particularly excellent as a copper foil for a secondary battery current collector with a long cycle life, and in order to have excellent handling properties, no wrinkles are formed on the copper foil in the active material coating line, From these characteristics, it is possible to easily provide a negative electrode for a lithium ion secondary battery with improved cycle characteristics, and to provide a lithium ion secondary battery with a long cycle life incorporating the negative electrode for the lithium ion secondary battery. I have it.
In addition, as described above, the present invention has an excellent effect of providing a printed wiring board having excellent characteristics and an electromagnetic wave shielding material.

Claims (7)

  On at least one of the matte surface and shiny surface of the electrolytic copper foil, the ten-point average surface roughness Rz is 2.0 μm or less, the glossiness Gs (60 °) is 40 or more and 150 or less, and the dynamic friction coefficient is 0.11 or more and 0. An electrolytic copper foil having a tensile strength of 300 MPa or more measured at room temperature after heating at 150 ° C. for 1 hour.   The electrolytic copper foil according to claim 1, wherein the tensile strength measured at room temperature after heating at 150 ° C for 1 hour is 400 MPa or more.   The electrolytic copper foil according to claim 1 or 2, wherein the foil thickness is 4 µm or more and 10 µm or less.   The negative electrode for lithium ion secondary batteries which used the electrolytic copper foil in any one of Claims 1-3 as a collector.   A lithium ion secondary battery using the current collector according to claim 4.   The printed wiring board formed by laminating | stacking the electrolytic copper foil and insulating film in any one of Claims 1-3.   The electromagnetic wave shielding material formed by laminating | stacking the electrolytic copper foil and insulating substrate in any one of Claims 1-3.