TWI490374B - Electrolytic copper foil, and a secondary battery collector and a secondary battery using the same - Google Patents

Description

Electrolytic copper foil, and secondary battery collector and secondary battery using same

The present invention relates to an electrolytic copper foil which is preferably a negative electrode current collector material of a secondary battery typified by a lithium ion secondary battery, and a secondary battery current collector and a secondary battery using the same.

With the popularity of portable devices such as mobile phones and notebook computers, the demand for small and high-capacitance secondary batteries is growing. In addition, the demand for large secondary batteries used in electric vehicles or hybrid vehicles has also increased rapidly. Among secondary batteries, lithium ion secondary batteries are used in many fields because of their light weight and high energy density.

As a lithium ion secondary battery, a compound in which a compound such as LiCoO ₂ , LiNiO ₂ , or LiMn ₂ O ₄ is coated on an aluminum foil is used as a positive electrode, and a carbonaceous material or the like is applied as an active material to a copper foil. Used as a negative electrode.

In general, a copper foil negative electrode plate is produced by using the electrolytic copper foil or the rolled copper foil according to the following process.

(1) A paste obtained by kneading a dispersion of an active material and a binder in a solvent is applied to one side or both sides of a copper foil to be a current collector to prepare a negative electrode plate.

(2) Drying by heating at a temperature of 150 to 300 ° C for several hours to several tens of hours.

(3) Pressurize the negative plate as needed.

(4) Performing a shearing process to form a negative electrode plate of a specific shape.

In Patent Document 1, "when the thickness of the current collector is made thinner, the strength of the current collector becomes weak, and when it is stored at a high temperature or when it is repeatedly charged and discharged, an active material self-collecting body occurs. The problem of peeling off or falling off may promote the decrease in capacitance due to breakage of the current collector during charge and discharge, and discloses a technique for improving the charge and discharge cycle characteristics of the battery by increasing the strength of the current collector. Specifically, it is known that the tensile strength and the mechanical properties such as elongation of the current collector are affected by the peak intensity ratio of the (200) and (100) planes, and further, there is an appropriate range in the peak intensity ratio, and the following are disclosed. The technique is to limit the peak intensity ratio of the (200) to (100) planes to a specific range by heat-treating copper or a copper alloy in a non-oxygen environment.

Further, in Patent Document 2, "the electrode active material such as carbon lacks affinity with a general metal surface such as copper. Therefore, even if a coating of a resin as a binder is added to the electrode active material, the coating is applied to the surface of the copper foil. Since the adhesion between the layer and the surface of the copper foil is still low, when the copper foil is subjected to winding or the like for use as a cathode, the active material and the surface of the copper foil are poorly bonded, so that the active material as a current collector is used. In the case of an increase in the resistance of the copper foil, the durability or the life of the cathode, there is a case where the adhesion of the coating which is originally lacking in affinity with the surface of the copper foil and the surface of the copper foil is improved. Technology. Specifically, it is known that the ratio of the specific crystal orientation of the copper foil side greatly affects the adhesion of the oxide film on the surface of the copper foil to a coating such as carbon, and when the ratio of the specific crystal orientation is a specific range The adhesion to the coating layer can be remarkably improved, and the following technique is disclosed, that is, as a specific crystal orientation, the integrated intensity ratio (200)/(220) of the crystal orientation of the 200 faces and the 220 faces of the copper foil is focused on. The integrated intensity ratio is limited to a specific range by adjusting the cold rolling ratio after the final annealing.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-142106

[Patent Document 2] Japanese Patent Laid-Open No. Hei 11-310864

However, in Patent Documents 1 and 2, there is disclosed a technique of attempting to control a specific crystal orientation of copper or a copper alloy to improve physical properties such as cycle characteristics or durability, but the physical properties are based on copper in a state before application of an active material. Or copper alloy for evaluation.

On the other hand, even if the control of the specific crystal orientation can be achieved, there is still an inconsistency in the case of insufficient charge/discharge cycle characteristics.

For the inconsistency, the reason is studied, and as a result, it is known that in the drying step of the active material after being applied to the copper or copper alloy, the heating process is usually carried out at 150 ° C to 200 ° C for about 1 hour, due to the drying step. The inconsistency of the heat causes a change in the crystal orientation of the copper or copper alloy, and as a result, the charge and discharge cycle characteristics become unstable. Therefore, it has been found that the problem can be solved by setting the range of change before and after the heat treatment of the specific crystal orientation within a certain range, and the present invention has been completed.

That is, the present invention is as follows.

(1) An electrolytic copper foil comprising copper or a copper alloy, which is irradiated with CuKα rays for the copper or copper alloy before heating at any one of 120 ° C, 130 ° C, 150 ° C, and 200 ° C for 1 hour. The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the source, the maximum value of the rate of change obtained by the following equation is 30% or less, and the maximum rate of change Value = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100.

(2) An electrolytic copper foil consisting of copper or a copper alloy, which is irradiated with CuKα rays for the copper or copper alloy before heating at any temperature of 120 ° C, 130 ° C, 150 ° C, and 200 ° C for 1 hour. The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the source, the maximum value of the rate of change obtained by the following equation is 10% or less, and the maximum rate of change Value = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100.

(3) An electrolytic copper foil consisting of copper or a copper alloy, which is irradiated with CuKα rays for the copper or copper alloy before heating at any temperature of 120 ° C, 130 ° C, 150 ° C, and 20 ° C for 1 hour. The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the source, the maximum value of the rate of change obtained by the following equation is 5% or less, and the maximum rate of change Value = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100.

(4) An electrolytic copper foil comprising copper or a copper alloy, which is irradiated with CuKα rays for the copper or copper alloy before heating at any temperature of 120 ° C, 130 ° C, 150 ° C, and 200 ° C for 1 hour. The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the source, and the maximum value of the absolute value of the rate of change defined below is 30% or less, here, The maximum value of the absolute value of the rate of change is the larger of the value of the absolute value of the maximum value of the rate of change or the absolute value of the minimum value of the rate of change, and the maximum value of the rate of change = (( Diffraction intensity ratio after heating) - (diffraction intensity ratio before heating) / (diffraction intensity ratio before heating) × 100, minimum value of change rate = ((diffraction intensity ratio after heating is minimum) Value) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100.

(5) An electrolytic copper foil comprising copper or a copper alloy, which is irradiated with CuKα rays for the copper or copper alloy before heating at any temperature of 120 ° C, 130 ° C, 150 ° C, and 200 ° C for 1 hour. The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the source, and the maximum value of the absolute value of the rate of change defined below is 10% or less, here, The maximum value of the absolute value of the rate of change is the larger of the value of the absolute value of the maximum value of the rate of change or the absolute value of the minimum value of the rate of change, and the maximum value of the rate of change = (( Diffraction intensity ratio after heating) - (diffraction intensity ratio before heating) / (diffraction intensity ratio before heating) × 100, minimum value of change rate = ((diffraction intensity ratio after heating is minimum) Value) - (diffraction before heating) Intensity ratio)) / (diffraction intensity ratio before heating) × 100.

(6) An electrolytic copper foil comprising copper or a copper alloy, which is irradiated with CuKα rays for the copper or copper alloy before heating at any temperature of 120 ° C, 130 ° C, 150 ° C, and 200 ° C for 1 hour. The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the source, and the maximum value of the absolute value of the rate of change defined below is 5% or less, here, The maximum value of the absolute value of the rate of change is the larger of the value of the absolute value of the maximum value of the rate of change or the absolute value of the minimum value of the rate of change, and the maximum value of the rate of change = (( Diffraction intensity ratio after heating) - (diffraction intensity ratio before heating) / (diffraction intensity ratio before heating) × 100, minimum value of change rate = ((diffraction intensity ratio after heating is minimum) Value) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100.

(7) The electrolytic copper foil according to any one of (1) to (6), which has a diffraction intensity ratio (200)/(()) and (111) plane after heating at 200 ° C for 1 hour. 111) is 0.25~5.00.

(8) The electrolytic copper foil according to any one of (1) to (7), wherein, for the diffraction intensity ratio (200) / (111), the minimum value of the change rate obtained by the following formula is a negative value The minimum value of the change rate = ((the diffraction intensity ratio after heating is the minimum value) - (the diffraction intensity ratio before heating)) / (the diffraction intensity ratio before heating) × 100.

(9) A method for producing an electrolytic copper foil, which is used for producing the electrolytic copper foil according to any one of (1) to (8), wherein the method is as follows: adding an aqueous solution for electrolysis to an electrolytic solution containing at least a copper source The gel having a mass ratio of 2 ppm or more was electrolyzed under the foil-forming conditions adjusted to have a limiting current density ratio of 0.170 or less.

(10) A secondary battery current collector using the electrolytic copper foil according to any one of (1) to (8).

(11) A secondary battery using the electrolytic copper foil according to any one of (1) to (8) for collecting electricity body.

According to the present invention, it is possible to provide an electrolytic copper foil which is excellent in charge and discharge cycle life as a negative electrode current collector material of a secondary battery typified by a lithium ion secondary battery, and a secondary battery current collector using the same And secondary batteries.

1‧‧‧ sealing plate

2‧‧‧Insulation gasket

3‧‧‧positive lead

4‧‧‧Upper insulation board

5‧‧‧ positive plate

6‧‧‧Negative plate

7‧‧‧Parts

8‧‧‧ battery case

9‧‧‧Negative lead

10‧‧‧Lower insulation board

Fig. 1 is a schematic view showing the structure of a general secondary battery.

(electrolytic copper foil)

The electrodeposited copper foil of the present embodiment is made of copper or a copper alloy, and is heated by the CuKα ray for the copper or copper alloy before heating at any of 120 ° C, 130 ° C, 150 ° C, and 200 ° C for 1 hour. The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the source is 30% or less of the maximum value of the absolute value of the rate of change obtained by the following equation. Here, the diffraction intensity of each of (200) and (111) is measured based on the peak intensity in XRD or the integrated intensity of the peak, and the diffraction intensity ratio is an index calculated from the ratio of the intensities.

Maximum value of change rate = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100

Further, in the electrodeposited copper foil of the present embodiment, the value of the diffraction intensity ratio (200) / (111) after heating at 200 ° C for 1 hour is preferably in the range of 0.25 to 5.00, particularly preferably in the range of 0.25 to 4.00. . Further, when the maximum value of the absolute value of the change rate obtained by the following method is 30% or less, the diffraction intensity ratio (200)/(111) is stable even when the heating crystallinity is applied, so that the cycle characteristics can be suppressed. Inconsistency is preferred from this point of view. Further, when the minimum value of the rate of change of the diffraction intensity ratio (200) / (111) does not take a negative value, the maximum value of the rate of change is preferably 30% or less.

Here, the maximum value of the absolute value of the change rate is a value which is a larger value of the absolute value of the maximum value of the change rate obtained by the following equation and the absolute value of the minimum value of the change rate.

Minimum value of change rate = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100

Maximum value of change rate = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100

According to another aspect, the present invention provides an electrolytic copper foil having a maximum value of the absolute value of the rate of change of the diffraction intensity ratio (200)/(111) or a maximum value of the rate of change of 10% or less.

Further, according to another aspect, the present invention provides an electrolytic copper foil having a maximum value of the absolute value of the rate of change of the diffraction intensity ratio (200)/(111) or a maximum value of the change rate of 5% or less. .

The thickness of the electrodeposited copper foil of the present embodiment can suppress the fall of the active material by increasing the tensile strength, so that the larger the value, the better. However, when the thickness of the current collector is increased, the void volume inside the battery is reduced and the energy density is lowered. Therefore, the thickness is preferably 15 μm or less, and most preferably 6 to 12 μm.

Further, as the copper alloy for electrolytic copper foil, a copper alloy containing 0.01 to 30% by weight of zinc, silver or tin is preferably added to the copper. Also, copper of higher purity can be used. The copper or copper alloy may be any one that satisfies the characteristics such as endurance, heat resistance, flexibility, and electrical conductivity necessary for the application of the nonaqueous electrolyte secondary battery, particularly by controlling phosphorus (P) or iron ( The amount of the element added to the trace amount of copper, such as Fe) or silver (Ag), can be improved in the range which does not adversely affect the battery performance. Further, nickel (Ni), tin (Sn), or the like contained as an unavoidable impurity can be tolerated as long as it does not adversely affect the battery performance.

Such an electrolytic copper foil can be added to a solution for electrolysis using at least a copper source and, if necessary, other metal components, and is adjusted to a limit current limit ratio. Obtained by electrolysis under the conditions of the foil production.

Here, the amount of the gum added to the aqueous solution for electrolysis is 2 ppm or more, preferably 6 ppm or more, based on the weight ratio of the aqueous solution for electrolysis.

Further, the current density is adjusted so that the ratio of the limiting current density is 0.170 or less, preferably 0.160 or less.

In the present invention, the limiting current density ratio is calculated according to the following equation.

Limit current density ratio = actual current density / limit current density

The limiting current density varies depending on the copper concentration, the sulfuric acid concentration, the feed rate, the interelectrode distance, and the electrolyte temperature. In the present invention, normal plating (a state in which copper is precipitated in a layer) and rough plating are used. (Scorch plating, the current density of the foil-forming conditions in which the copper is precipitated in the form of crystals (spherical or needle-like or hoarfrost), and the boundary of the irregularities is defined as the limiting current density, and is tested in the Hall cell. In (Hull cell test), the current density (visual judgment) which is the limit of normal plating (before becoming burnt plating) is taken as the limiting current density.

Specifically, in the Hall cell test, the Hall concentration test was carried out by setting the copper concentration, the sulfuric acid concentration, and the electrolyte temperature to the production conditions of the copper foil. Then, the electrolyte composition and the state of formation of the copper layer at the temperature of the electrolyte (copper precipitated or formed into a crystal form) were investigated. Then, based on the current density profile produced by Yamamoto Gold Platter Tester Co., Ltd., the position of the boundary is obtained from the position of the sample where the normal plating of the test piece and the boundary of the rough plating are present. Current density. Then, the current density at the position of the boundary is defined as the limiting current density. Thereby, the limit current density at the electrolyte composition and the electrolyte temperature can be known. In general, if the distance between the electrodes is short, the limiting current density tends to be high. In the examples, the sample used in the Hall cell test was a transverse copper plate for Hall cell test manufactured by Yamamoto Gold Plating Tester Co., Ltd.

Further, in the conventional example, an electrolytic copper foil was produced to adjust the shape of the copper foil particles by setting the limiting current density ratio to be greater than 0.17. The method of the Hall groove test is described, for example, in Maruyama The 157 pages to 160 pages of the "Plating Practice Book" published by the Nikkan Kogyo Shimbun newspaper on June 30, 1983.

According to the electrolytic copper foil obtained in this way, the metal structure becomes fine, and the gel penetrates into the copper foil in an average state. Further, even if the electrolytic copper foil which has been infiltrated with the rubber evenly is subjected to heat treatment, the metal structure does not easily change, and the crystal orientation becomes stable. As a result, when the copper foil is used as a current collector and a negative electrode is produced to form a battery, the charge and discharge cycle characteristics of the battery are also improved.

(Battery composition)

The negative electrode plate and the secondary battery of the present embodiment are characterized in that the copper foil is used as a negative electrode current collector, and the other configuration is not limited, and a commonly used one can be used. In addition, a typical secondary battery includes, for example, a separator group in which a negative electrode plate is partitioned and a positive electrode plate in which a lithium transition metal composite oxide is used as a main component of a positive electrode active material, and a non-aqueous electrolyte solution, and A battery case that houses the electrode group and the non-aqueous electrolyte.

(negative electrode)

The negative electrode is composed of the above-described negative electrode current collector and a negative electrode active material formed on one surface or both surfaces of the negative electrode current collector. Examples of the negative electrode active material include a carbonaceous material capable of absorbing and releasing lithium, a metal, a metal compound (metal oxide, metal sulfide, metal nitride), and a lithium alloy.

Examples of the carbonaceous material include a graphite material such as graphite, coke, carbon fiber, spherical carbon, a thermally decomposable gas phase carbonaceous material, or a resin fired material, or a carbonaceous material; and a thermosetting resin at 500 to 3000 ° C A graphite material or a carbonaceous material obtained by heat treatment such as an isotropic pitch, a mesophase pitch-based carbon, a mesophase pitch-based carbon fiber, or a mesophase small sphere.

Examples of the metal include lithium, aluminum, magnesium, tin, antimony, and the like.

Examples of the metal oxide include tin oxide, cerium oxide, lithium titanium oxide, cerium oxide, and tungsten oxide. Examples of the metal sulfides include tin sulfides and titanium sulfides. Examples of the metal nitride include lithium cobalt nitride, lithium iron nitride, and lithium manganese. Nitride and the like.

Examples of the lithium alloy include a lithium aluminum alloy, a lithium tin alloy, a lithium lead alloy, and a lithium niobium alloy.

A binder may be contained in the negative electrode active material-containing layer. As a binder, a mixture containing carboxymethylcellulose (CMC) and styrene butadiene (SBR) is mentioned. By using a binder containing CMC and SBR, the adhesion between the negative electrode active material and the current collector can be further improved.

A conductive agent may be contained in the negative electrode active material-containing layer. Examples of the conductive agent include graphites such as acetylene black and powdery expanded graphite, carbon fiber pulverized materials, and graphitized carbon fiber pulverized materials.

The present invention provides a secondary battery current collector obtained in the above manner.

(positive electrode)

The positive electrode is composed of a positive electrode current collector and a positive electrode active material-containing layer formed on one surface or both surfaces of the positive electrode current collector.

Examples of the positive electrode current collector include an aluminum plate and an aluminum mesh material.

The positive electrode active material-containing layer contains, for example, an active material and a binder. Examples of the positive electrode active material include chalcogen compounds such as manganese dioxide, molybdenum disulfide, LiCoO ₂ , LiNiO ₂ , and LiMn ₂ O ₄ . These chalcogen compounds may be used in combination of two or more kinds. As the binder, a thermoplastic elastomer resin such as a fluorine resin, a polyolefin resin, a styrene resin or an acrylic resin; or a rubber resin such as a fluororubber can be used.

Further, as the conductive auxiliary material, a graphite such as acetylene black or powdery expanded graphite, a carbon fiber pulverized product, or a graphitized carbon fiber pulverized material may be contained in the active material-containing layer.

(separator)

A separator or a solid or gel electrolyte layer may be disposed between the positive electrode and the negative electrode. As the separator, for example, a polyethylene porous film having a thickness of 20 to 30 μm, a polypropylene porous film, or the like can be used.

(non-aqueous electrolyte)

The nonaqueous electrolyte can be used in the form of a liquid, a gel or a solid. Further, the nonaqueous electrolyte is preferably an electrolyte containing a nonaqueous solvent and dissolved in the nonaqueous solvent.

Examples of the nonaqueous solvent include ethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, and γ-butyrolactone. The type of the nonaqueous solvent to be used may be one or two or more.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), and lithium hexafluoroarsenide (LiAsF ₆ ). The electrolyte may be used singly or in the form of a mixture.

The present invention provides a negative electrode comprising a secondary battery current collector, and a secondary battery comprising the members and configured by the following method.

[Examples]

(Manufacturing Example 1)

A titanium cylinder having a diameter of about 3,133 mm and a width of 2476.5 mm was placed in the electrolytic cell, and electrodes were placed at intervals of about 5 mm around the cylinder. An aqueous copper sulfate solution containing the additive of the concentration described in Table 1 was introduced into the electrolytic cell. Then, the ratio of the limiting current density ratio described in Table 1 was adjusted to deposit copper on the surface of the drum, and copper deposited on the surface of the drum was peeled off, and then the electrolytic copper foil of the following Invention Example 1 was produced. The thickness of the copper foil was 10 μm.

(Manufacturing Example 2 to 9)

An electrolytic copper foil was produced under the same conditions as in Production Example 1 except that the amount of addition shown in Table 1 and the ratio of the limiting current density were used. Further, the plate thicknesses of Production Examples 2, 3, 4, and 5 were 12 μm, 8 μm, 18 μm, and 10 μm, respectively. Further, the plate thicknesses of Production Examples 6 to 9 were 10 μm. Further, in Production Examples 2 to 9, the peeled copper foil was also supplied to the production of the electrolytic copper foil of the invention example or the comparative example described later.

(Inventive Examples 1 to 5)

The electrolytic copper foils of Production Examples 1 to 5 were subjected to heat treatment. Further, each of the electrolytic copper foils was subjected to heat treatment at 120 ° C, 130 ° C, 150 ° C, and 200 ° C for 1 hour. The diffraction intensity of each of the heated (200) plane and the (111) plane by XRD using CuKα ray as a radiation source was measured.

Further, the maximum value of the maximum value, the minimum value, and the absolute value of the rate of change of the diffraction intensity ratio (200)/(111) in the crystal orientation of the (200) plane and the (111) plane is obtained by the following equation. And the maximum value of the absolute value of the maximum value, the minimum value, and the change value of the change value.

The results are shown in Table 2.

*1 Minimum value of change rate = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating) / (diffraction intensity ratio before heating) × 100

*2 Maximum value of change rate = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100

The maximum value of the absolute value of the rate of change is a larger value of the value of the absolute value of the maximum value of the above-described rate of change and the value of the absolute value of the minimum value of the rate of change.

*3 The minimum value of the change value = (the diffraction intensity ratio after heating is the minimum value) - (the diffraction intensity ratio before heating)

*4 The maximum value of the change value = (the diffraction intensity ratio after heating is the maximum value) - (the diffraction intensity ratio before heating)

The maximum value of the absolute value of the change value is set to a larger value of the absolute value of the maximum value of the change value and the absolute value of the minimum value of the change value.

(Comparative examples 1 to 4)

The electrolytic copper foil obtained in each of Production Examples 6 to 9 was subjected to heat treatment in the same manner as in Inventive Example 1. Further, the maximum value and the minimum value of the rate of change of the diffraction intensity ratio (200)/(111) in the crystal orientation of the (200) plane and the (111) plane, and the maximum value and the minimum value of the change value are obtained.

The results are shown in Table 2.

(Evaluation of charge and discharge cycle characteristics)

With respect to the copper foil obtained in the above examples and comparative examples, the following procedure was used to produce the FIG. A cylindrical lithium ion secondary battery was shown and the cycle life was measured.

(1) 50 parts by weight of flaky graphite powder as a negative electrode active material, 5 parts by weight of styrene butadiene rubber as a binder, and 1 part by weight as a tackifier with respect to carboxymethylcellulose in water 23 parts by weight of an aqueous solution of a tackifier prepared in 99 parts by weight was kneaded and dispersed to obtain a paste for a negative electrode. This negative electrode paste was applied to the surface of the rolled copper foil sample by a doctor blade method at a thickness of 200 μm, and dried by heating at 200 ° C for 30 minutes. After pressurizing and adjusting the thickness to 160 μm, it was molded by shearing to obtain a negative electrode plate 6.

(2) 50 parts by weight of LiCoO ₂ powder as a positive electrode active material, 1.5 parts by weight of acetylene black as a conductive agent, 7 parts by weight of a PTFE 50% aqueous dispersion as a binder, and carboxymethyl cellulose 1 as a tackifier 41.5 parts by weight of the % aqueous solution was kneaded and dispersed to obtain a paste for a positive electrode. This positive electrode paste was applied on both sides of a current collector made of an aluminum foil having a thickness of 30 μm by a doctor blade method at a thickness of about 230 μm, and dried by heating at 200 ° C for 1 hour. After pressurizing and adjusting the thickness to 180 μm, it was molded by shearing to obtain a positive electrode plate 5.

(3) The positive electrode plate 5 and the negative electrode plate 6 are wound in a spiral shape with a separator 7 made of a microporous film made of a polypropylene resin having a thickness of 20 μm, and the electrode group thus obtained is housed in a spiral shape. In the battery case 8.

(4) The negative electrode lead 9 connected from the negative electrode plate 6 is electrically connected to the outer casing 8 via the lower insulating plate 10. Similarly, the positive electrode lead 3 connected from the positive electrode plate 5 is electrically connected to the internal terminal of the sealing plate 1 via the upper insulating plate 4. Thereafter, a non-aqueous electrolyte solution was injected, and the sealing plate 1 and the battery can 8 were caulked and sealed via an insulating gasket 2, and a cylindrical lithium ion having a battery capacity of 780 mAh was produced in a size of 17 mm in diameter and 50 mm in height. Secondary battery.

(5) In the electrolyte solution, a specific amount of lithium hexafluorophosphate (LiPF) as an electrolyte is dissolved in a mixed solvent of 30% by volume of ethyl carbonate, 50% by volume of ethyl methyl carbonate, and 20% by volume of methyl propionate. ₆ ) 1.0 mole of electrolyte. This electrolyte solution is impregnated into the positive electrode active material layer and the negative electrode active material layer.

Next, with respect to the batteries obtained in the above Examples and Comparative Examples, 20 batteries were used, and the charge and discharge cycle characteristics were evaluated.

Here, the charge and discharge cycle characteristics were evaluated by repeating a charge and discharge cycle composed of the following charging conditions and discharge conditions in an environment of 20 ° C.

- Charging conditions: constant current charging at 4.2V for 2 hours - constant current charging at 550 mA (0.7 CmA) before the battery voltage reaches 4.2 V, and then charging until the current value decays to 40 mA (0.05 CmA) until.

-Discharge condition: When discharging at a constant current of 780 mA (1 CmA) to a discharge termination voltage of 3.0 V, the capacitance in the third cycle is used as an initial capacitance, and the cycle is calculated until the discharge capacitance is reduced to 80% with respect to the initial capacitance. number. The results of the average of the number of charge and discharge cycles are shown in Table 3.

Claims (12)

An electrolytic copper foil consisting of copper or a copper alloy, and after being heated at any temperature of 120 ° C, 130 ° C, 150 ° C, and 200 ° C for 1 hour, the surface of the copper or copper alloy is irradiated with CuK α rays. The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the source, the maximum value of the rate of change obtained by the following equation is 30% or less, and the maximum rate of change Value = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100. An electrolytic copper foil consisting of copper or a copper alloy, after heating at any temperature of 120 ° C, 130 ° C, 150 ° C and 200 ° C for 1 hour, the surface of the copper or copper alloy is ° CuK α ray The diffraction intensity ratio (200)/(111) between the (200) plane and the (111) plane in the X-ray diffraction of the radiation source, and the maximum value of the change rate obtained by the following equation is 10% or less, and the rate of change Maximum value = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100. An electrolytic copper foil consisting of copper or a copper alloy, after heating at any temperature of 120 ° C, 130 ° C, 150 ° C and 200 ° C for 1 hour, the surface of the copper or copper alloy is ° CuK α ray The diffraction intensity ratio (200)/(111) between the (200) plane and the (111) plane in the X-ray diffraction of the radiation source, and the maximum value of the change rate obtained by the following equation is 5% or less, and the rate of change Maximum value = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100. An electrolytic copper foil consisting of copper or a copper alloy, after heating at any temperature of 120 ° C, 130 ° C, 150 ° C and 200 ° C for 1 hour, the surface of the copper or copper alloy is ° CuK α ray The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the radiation source, and the maximum value of the absolute value of the rate of change defined below is 30% or less, here The maximum value of the absolute value of the change rate is a value which is a larger value of the absolute value of the maximum value of the change rate or the absolute value of the minimum value of the change rate. Maximum value of change rate = ((diffraction intensity ratio after heating) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100, minimum value of change rate = (( The diffraction intensity ratio after heating is the minimum value - (diffraction intensity ratio before heating) / / (diffraction intensity ratio before heating) × 100. An electrolytic copper foil consisting of copper or a copper alloy, and after being heated at any temperature of 120 ° C, 130 ° C, 150 ° C, and 200 ° C for 1 hour, the surface of the copper or copper alloy is irradiated with CuK α rays. The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the source, and the maximum value of the absolute value of the rate of change defined below is 10% or less, here, The maximum value of the absolute value of the rate of change is the larger of the value of the absolute value of the maximum value of the rate of change or the absolute value of the minimum value of the rate of change, and the maximum value of the rate of change = (( Diffraction intensity ratio after heating) - (diffraction intensity ratio before heating) / (diffraction intensity ratio before heating) × 100, minimum value of change rate = ((diffraction intensity ratio after heating is minimum) Value) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100. An electrolytic copper foil consisting of copper or a copper alloy, and after being heated at any temperature of 120 ° C, 130 ° C, 150 ° C, and 200 ° C for 1 hour, the surface of the copper or copper alloy is irradiated with CuK α rays. The diffraction intensity ratio (200)/(111) of the (200) plane and the (111) plane in the X-ray diffraction of the source, and the maximum value of the absolute value of the rate of change defined below is 5% or less, here, The maximum value of the absolute value of the rate of change is the larger of the value of the absolute value of the maximum value of the rate of change or the absolute value of the minimum value of the rate of change, and the maximum value of the rate of change = (( Diffraction intensity ratio after heating) - (diffraction intensity ratio before heating) / (diffraction intensity ratio before heating) × 100, minimum value of change rate = ((diffraction intensity ratio after heating is minimum) Value) - (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100. An electrolytic copper foil according to any one of claims 1 to 6, which is heated at 200 ° C. The diffraction intensity ratio (200) / (111) of the (200) plane and the (111) plane after the hour is 0.25 to 5.00. The electrolytic copper foil according to any one of claims 1 to 6, wherein, for the diffraction intensity ratio (200) / (111), the minimum value of the rate of change obtained according to the following formula is a negative value, and the change The minimum value of the rate = ((the diffraction intensity ratio after heating is the minimum value) - (the diffraction intensity ratio before heating)) / (the diffraction intensity ratio before heating) × 100. The electrolytic copper foil according to item 7 of the patent application, wherein, for the diffraction intensity ratio (200) / (111), the minimum value of the rate of change obtained according to the following formula is a negative value, and the minimum value of the change rate = ( (Diffraction intensity ratio after heating) - ((diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100. The invention relates to a method for producing an electrolytic copper foil, which is used for manufacturing the electrolytic copper foil according to any one of claims 1 to 9, which is as follows: adding an aqueous solution for electrolysis for at least a copper source with an aqueous solution for electrolysis The gel having a ratio of 2 ppm or more was electrolyzed under the foil-forming conditions adjusted to have a limiting current density ratio of 0.170 or less. A secondary battery current collector using the electrolytic copper foil according to any one of claims 1 to 9. A secondary battery using the electrolytic copper foil according to any one of claims 1 to 9 for a current collector.