JP5698196B2 - Electrolytic copper foil, and secondary battery current collector and secondary battery using the same - Google Patents

Description

  The present invention relates to an electrolytic copper foil suitable as a negative electrode current collector material for a secondary battery such as a lithium ion secondary battery, a secondary battery current collector using the same, and a secondary battery.

With the widespread use of portable devices such as mobile phones and notebook computers, the demand for small, high-capacity secondary batteries is growing. In addition, demand for medium- and large-sized secondary batteries used in electric vehicles, hybrid vehicles, and the like is also increasing 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, an aluminum foil coated with a compound such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ is used as a positive electrode, and a copper foil coated with a carbonaceous material or the like as an active material is used as a negative electrode. What is used is known.

Generally, a copper foil negative electrode plate is manufactured by the following process using electrolytic copper foil or rolled copper foil.
(1) A paste obtained by kneading and dispersing an active material and a binder in a solvent is applied to one side or both sides of a copper foil serving as a current collector to form a negative electrode plate material.
(2) Heat and dry at 150 to 300 ° C. for several hours to several tens of hours.
(3) Pressurize the negative electrode plate material as necessary.
(4) A shearing process is performed to form a negative electrode plate having a predetermined shape.

  In Patent Document 1, when the current collector is thinned, the strength of the current collector becomes weak, and when it is stored at a high temperature or when charging and discharging are repeated, the active material from the current collector Disclosed is a technique for improving the charge / discharge cycle characteristics of a battery by improving the strength of the current collector, in response to problems such as peeling and dropping, and sometimes urging capacity reduction due to current collector breakage during charge / discharge. Has been. Specifically, the mechanical properties such as the tensile strength and elongation of the current collector are affected by the peak intensity ratio of the (200) and (100) planes, and there is an appropriate range for the peak intensity ratio. Thus, a technique is disclosed in which the peak intensity ratio between the (200) and (100) planes falls within a specific range by heat-treating copper or a copper alloy in a non-oxygen atmosphere.

  Further, in Patent Document 2, it is assumed that an electrode active material such as carbon is generally poor in affinity with a metal surface such as copper, and for that reason, a coating layer obtained by adding a resin as a binder to the electrode active material is provided on the copper foil surface. However, since the adhesion of the coating layer to the copper foil surface is still low, when the copper foil is wound for the cathode, the active material and the copper foil surface cause poor adhesion. In contrast to the increase in resistance between the active material that is the current collector and the copper foil, and the problem that durability and life as a cathode still remain, the coating with the copper foil surface is originally poor in affinity with the copper foil surface. A technique related to copper foil with improved adhesion is disclosed. Specifically, the abundance ratio of the specific crystal orientation on the copper foil side greatly affects the adhesion of the oxide film on the copper foil surface to the coating layer such as carbon, and the abundance ratio of this specific crystal orientation is specified. In this range, it was found that the adhesion with the coating layer was remarkably improved, and as a specific crystal orientation, the integrated intensity ratio (200) / (220) of the crystal orientation of the 200 plane and the 220 plane of the copper foil. In particular, a technique is disclosed in which the integrated intensity ratio is adjusted within a specific range by adjusting the cold rolling rate after the final annealing.

JP 2003-142106 A JP-A-11-310864

  By the way, although both patent documents 1 and 2 disclose a technique for controlling a specific crystal orientation of copper or a copper alloy to try to improve physical properties such as cycle characteristics or durability, the physical properties are before application of an active material. The copper or copper alloy in the state of is evaluated.

  On the other hand, even if the control of a specific crystal orientation can be realized, there are some inadequate from the viewpoint of charge / discharge cycle characteristics, and in fact, there are variations.

  As a result of investigating the cause of this variation, variation in the amount of heat in the drying step in heat treatment at 150 ° C. to 200 ° C. for about 1 hour, which is usually performed in the drying step after application of the active material to copper or copper alloy, As a result, the crystal orientation of copper or copper alloy was changed, and as a result, the charge / discharge cycle characteristics became unstable. Therefore, the inventors have found that this problem can be solved by setting the change width of the specific crystal orientation before and after the heat treatment within a certain range, and have completed the present invention.

That is, the present invention is as follows.
(1) In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy before and after heating for 1 hour at a temperature of 120 ° C., 130 ° C., 150 ° C. or 200 ° C. Electrolysis in which the maximum value of the rate of change obtained by the following formula is 30% or less with respect to the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction using as a radiation source Copper foil.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100
(2) In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy before and after heating for 1 hour at a temperature of 120 ° C., 130 ° C., 150 ° C. or 200 ° C. Electrolysis in which the maximum value of the rate of change obtained by the following equation is 10% or less with respect to the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction using as a radiation source Copper foil.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100
(3) In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy before and after heating at 120 ° C, 130 ° C, 150 ° C or 200 ° C for 1 hour. Electrolysis in which the maximum value of the rate of change obtained by the following equation is 5% or less with respect to the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction using as a radiation source Copper foil.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100
(4) In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy before and after heating for 1 hour at a temperature of 120 ° C., 130 ° C., 150 ° C. or 200 ° C. For the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction using as a radiation source, the maximum absolute value of the rate of change defined below is 30% or less. Some electrolytic copper foil.
Here, the maximum value of the absolute value of the change rate 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 obtained by the following equation.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100
Minimum value of rate of change = ((Minimum value of diffraction intensity ratio after heating) − (Diffraction intensity ratio before heating)) / (Diffraction intensity ratio before heating) × 100
(5) In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy before and after heating for 1 hour at a temperature of 120 ° C., 130 ° C., 150 ° C. or 200 ° C. For the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction using as a radiation source, the maximum absolute value of the rate of change defined below is 10% or less. Some electrolytic copper foil.
Here, the maximum value of the absolute value of the change rate 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 obtained by the following equation.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100
Minimum value of rate of change = ((Minimum value of diffraction intensity ratio after heating) − (Diffraction intensity ratio before heating)) / (Diffraction intensity ratio before heating) × 100
(6) In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy before and after heating for 1 hour at a temperature of 120 ° C., 130 ° C., 150 ° C. or 200 ° C. For the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction using as a radiation source, the maximum absolute value of the rate of change defined below is 5% or less. Some electrolytic copper foil.
Here, the maximum value of the absolute value of the change rate 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 obtained by the following equation.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100
Minimum value of rate of change = ((Minimum value of diffraction intensity ratio after heating) − (Diffraction intensity ratio before heating)) / (Diffraction intensity ratio before heating) × 100
(7) The diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane after heating at 200 ° C. for 1 hour is from 0.25 to 5.00 (1) to (6) Electrolytic copper foil in any one of.
(8) The electrolytic copper foil according to any one of (1) to (7), wherein the minimum value of the change rate obtained by the following formula is a negative value for the diffraction intensity ratio (200) / (111).
Minimum value of rate of change = ((Minimum value of diffraction intensity ratio after heating) − (Diffraction intensity ratio before heating)) / (Diffraction intensity ratio before heating) × 100
(9) A method for producing an electrolytic copper foil according to any one of (1) to (8),
At least 2 ppm of nickel is added to the aqueous solution for electrolysis containing at least a copper source in a mass ratio with respect to the aqueous solution for electrolysis, and electrolysis is performed under foil-making conditions adjusted so that the limiting current density ratio is 0.170 or less. A method characterized by that.
(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) as a current collector.

  According to the present invention, an electrolytic copper foil excellent in charge / discharge cycle life, which is suitable as a negative electrode current collector material for a secondary battery such as a lithium ion secondary battery, and a secondary battery current collector using the same. Provide the next battery.

It is the schematic which shows the structure of a general secondary battery.

(Electrolytic copper foil)
The electrolytic copper foil in the present embodiment is an electrolytic copper foil made of copper or a copper alloy, and before or after heating for 1 hour at any one of 120 ° C., 130 ° C., 150 ° C. and 200 ° C. The maximum absolute value of the rate of change obtained by the following equation for the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction using CuKα rays of a copper alloy as a radiation source The value is 30% or less. Here, the diffraction intensity on each of the surfaces (200) and (111) is measured from 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 these intensities.

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

  Moreover, in the electrolytic copper foil of this embodiment, it is preferable that the value of the diffraction intensity ratio (200) / (111) after heating at 200 ° C. for 1 hour is in the range of 0.25 to 5.00. Preferably, it is in the range of 0.25 to 4.00. Furthermore, with respect to the diffraction intensity ratio (200) / (111), the maximum value of the absolute value of the change rate obtained as follows is 30% or less, and the crystallinity is stable even when heating is applied. Therefore, it is preferable from the viewpoint of suppressing variation in cycle characteristics. In addition, when the minimum value of the change rate of the diffraction intensity ratio (200) / (111) does not take a negative value, the maximum value of the change rate is preferably 30% or less.

Here, the maximum value of the absolute value of the change rate is the larger of the absolute value of the maximum value of the change rate and the absolute value of the minimum value of the change rate obtained by the following formula.
Minimum value of rate of change = ((Minimum value of diffraction intensity ratio after heating) − (Diffraction intensity ratio before heating)) / (Diffraction intensity ratio before heating) × 100
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100

From another aspect, the present invention provides an electrolytic copper foil in which the absolute value of the change rate of the diffraction intensity ratio (200) / (111) described above is the maximum value or the maximum value of the change rate is 10% or less. provide.
Furthermore, from another aspect, the present invention provides an electrolytic copper having a maximum absolute value of the rate of change of the above-described diffraction intensity ratio (200) / (111) or a maximum value of the rate of change of 5% or less. Provide foil.

  In the present embodiment, the thickness of the electrolytic copper foil is preferably as large as possible because the active material can be prevented from falling off by increasing the tensile strength. However, when the current collector thickness is increased, the void volume inside the battery is decreased and the energy density is decreased. Therefore, the thickness is preferably 15 μm or less, and the range of 6 to 12 μm is optimal.

  Moreover, as a copper alloy used for electrolytic copper foil, the copper alloy which added 0.01-30 weight% of zinc, silver, and tin to copper is preferable. Moreover, you may use copper with high purity. These copper or copper alloys only need to satisfy characteristics such as proof stress, heat resistance, flexibility, and conductivity required for application to non-aqueous electrolyte secondary batteries. In particular, phosphorus (P) and iron By controlling the amount of element added to copper such as (Fe) and silver (Ag), the above characteristics can be improved within a range that does not adversely affect battery performance. Further, nickel (Ni), tin (Sn), and the like contained as inevitable impurities are acceptable as long as they do not adversely affect the battery performance.

  Such electrolytic copper foil is prepared by adding nickel to an aqueous solution for electrolysis containing at least a copper source and, if necessary, other metal components, and adjusting the foil production conditions so that the ratio of current density to limit is within a certain range. It can be obtained by performing electrolysis at.

Here, the amount of glue added to the aqueous solution for electrolysis is 2 ppm or more, preferably 6 ppm or more, by weight with respect to 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 limit current density ratio is calculated by the following equation.
Ratio of current density to limit = actual current density / limit current density The limit current density varies depending on the copper concentration, sulfuric acid concentration, liquid supply speed, distance between electrodes, and electrolyte temperature. Foil-making conditions that serve as a boundary between the layered state) and rough plating (burnt plating, copper is deposited in a crystalline form (spherical, needle-like, rime-like, etc., with irregularities)) Was defined as the critical current density, and the critical current density (visual judgment) at which the normal plating in the hull cell test was achieved (immediately before burn plating) was defined as the critical current density.

  Specifically, in the hull cell test, the hull cell test is performed by setting the copper concentration, the sulfuric acid concentration, and the electrolyte temperature to the production conditions of the copper foil. Then, the electrolytic solution composition and the copper layer formation state at the electrolytic solution temperature (whether copper is deposited in a layered form or a crystalline form) are investigated. Then, based on the current density chart made by Yamamoto Metal Testing Co., Ltd., the current density at the boundary position is obtained from the position of the test piece where the boundary between normal plating and rough plating of the test piece exists. It was. The current density at the boundary position was defined as the limit current density. Thereby, the limiting current density in the said electrolyte solution composition and electrolyte temperature is known. Generally, when the distance between the electrodes is short, the limit current density tends to increase. In the examples, the test piece used for the hull cell test was a copper plate for hull cell test manufactured by Yamamoto Metal Testing Co., Ltd.

  Conventionally, in order to adjust the shape of the copper foil particles, it was customary to produce an electrolytic copper foil with a limiting current density ratio larger than 0.17. The method of the Hull cell test is described in, for example, “Plating Practice Reader” by Kiyoshi Maruyama, Nikkan Kogyo Shimbun, Ltd., pages 157 to 160 on June 30, 1983.

  In the electrolytic copper foil obtained in this way, the metal structure becomes fine and the glue is averagely taken into the copper foil. Further, the electrolytic copper foil in which glue is taken in on average is less likely to change the metal structure even after heat treatment, and the crystal orientation is stabilized. As a result, when the copper foil is used as a current collector to produce a negative electrode and a battery, the charge / discharge cycle characteristics of the battery are also improved.

(Battery configuration)
The negative electrode plate and the secondary battery in the present embodiment are characterized by using the copper foil as a negative electrode current collector. Other configurations are not limited, and commonly used known ones are used. Can be used. In addition, a typical secondary battery includes, for example, a positive electrode plate in which a negative electrode plate is mainly composed of a lithium transition metal composite oxide as a main component of a positive electrode active material, an electrode plate group insulatively arranged via a separator, and a non-aqueous electrolyte. And a battery case containing the electrode plate group and the non-aqueous electrolyte.

(Negative electrode)
A negative electrode is comprised from the said negative electrode collector and the negative electrode active material formed in the single side | surface or both surfaces of a negative electrode collector. Examples of the negative electrode active material include carbonaceous materials capable of occluding and releasing lithium, metals, metal compounds (metal oxides, metal sulfides, metal nitrides), lithium alloys, and the like.

Examples of the carbonaceous material include graphite materials, carbonaceous materials such as graphite, coke, carbon fiber, spherical carbon, pyrolytic vapor phase carbonaceous material, and resin fired body; thermosetting resin, isotropic pitch, and mesophase pitch carbon. Examples thereof include graphite materials or carbonaceous materials obtained by subjecting mesophase pitch-based carbon fibers, mesophase microspheres, etc. to heat treatment at 500 to 3000 ° C.
Examples of the metal include lithium, aluminum, magnesium, tin, and silicon.
Examples of the metal oxide include tin oxide, silicon oxide, lithium titanium oxide, niobium oxide, and tungsten oxide. Examples of the metal sulfide include tin sulfide and titanium sulfide. Examples of the metal nitride include lithium cobalt nitride, lithium iron nitride, and lithium manganese nitride.
Examples of the lithium alloy include a lithium aluminum alloy, a lithium tin alloy, a lithium lead alloy, and a lithium silicon alloy.

The negative electrode active material-containing layer can contain a binder. Examples of the binder include a mixture containing carboxymethyl cellulose (CMC) and styrene butadiene (SBR). By using a binder containing CMC and SBR, the adhesion between the negative electrode active material and the current collector can be further increased.
The negative electrode active material-containing layer can contain a conductive agent. Examples of the conductive agent include acetylene black, graphite such as powdered expanded graphite, pulverized carbon fiber, pulverized graphitized carbon fiber, and the like.
The present invention provides a secondary battery current collector thus obtained.

(Positive electrode)
The positive electrode includes a positive electrode current collector and a positive electrode active material-containing layer formed on one 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 a mixture of two or more. As the binder, a fluoroelastomer resin, a polyolefin resin, a styrene resin, a thermoplastic elastomer resin such as an acrylic resin, or a rubber resin such as fluororubber can be used.
The active material-containing layer may further contain acetylene black, graphite such as powdered expanded graphite, carbon fiber pulverized material, graphitized carbon fiber pulverized material, and the like as a conductive auxiliary material.

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

(Nonaqueous electrolyte)
As the non-aqueous electrolyte, those having a liquid, gel or solid form can be used. The non-aqueous electrolyte preferably includes a non-aqueous solvent and an electrolyte that is dissolved in the non-aqueous solvent.
Examples of the non-aqueous solvent include ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, and γ-butyrolactone. The kind of nonaqueous solvent to be used can be one kind or two or more kinds.
Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and the like. The electrolyte can be used alone or in the form of a mixture.

  This invention provides the secondary battery comprised as follows, including the negative electrode comprised from a secondary battery electrical power collector, and these members.

(Production Example 1)
In the electrolytic cell, a titanium rotating drum having a diameter of about 3133 mm and a width of 2476.5 mm and an electrode distance of about 5 mm were arranged around the drum. An aqueous copper sulfate solution containing additives having the concentrations shown in Table 1 was introduced into this electrolytic cell. And it adjusted to the limiting current density ratio of Table 1, copper was deposited on the surface of the rotating drum, the copper deposited on the surface of the rotating drum was peeled off, and then the electrolytic copper foil of Invention Example 1 to be described later Manufactured. The thickness of the copper foil was 10 μm.

(Production Examples 2-9)
An electrolytic copper foil was produced under the same conditions as in Production Example 1 except that the addition amount shown in Table 1 and the ratio of the limiting current density were used. The plate thicknesses of Production Examples 2, 3, 4, and 5 were 12 μm, 8 μm, 18 μm, and 10 μm, respectively. Further, the thicknesses of Production Examples 6 to 9 were 10 μm. Moreover, also about the manufacture examples 2-9, the stripped copper foil was used for manufacture of the electrolytic copper foil of the invention example or comparative example mentioned later.

(Invention Examples 1 to 5)
About the electrolytic copper foil of the manufacture examples 1-5, heat processing was performed. In addition, about each electrolytic copper foil, heat processing were performed at 120 degreeC for 1 hour, 130 degreeC for 1 hour, 150 degreeC for 1 hour, and 200 degreeC for 1 hour. The diffraction intensity by XRD using CuKα rays on the (200) plane and (111) plane after each heating as a radiation source was measured.
Furthermore, the maximum value of the change rate of the diffraction intensity ratio (200) / (111) in the crystal orientation of the (200) plane and the (111) plane, the minimum value, the maximum absolute value of the change rate, and the maximum value of the change value The maximum value of the absolute value of the minimum value and the change value was obtained by the following formula.
The results are shown in Table 2.

* 1 Minimum value of change rate = ((Minimum value of diffraction intensity ratio after heating) − (Diffraction intensity ratio before heating)) / (Diffraction intensity ratio before heating) × 100
* 2 Maximum value of change rate = ((maximum value of 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 change rate is the larger value of the absolute value of the maximum value of the change rate and the absolute value of the minimum value of the change rate.
* 3 Minimum value of change value = (Minimum value of diffraction intensity ratio after heating)-(Diffraction intensity ratio before heating)
* 4 Maximum change value = (Maximum diffraction intensity ratio after heating)-(Diffraction intensity ratio before heating)
The maximum value of the absolute value of the change value is the 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 1-4)
About the electrolytic copper foil obtained by manufacture examples 6-9, respectively, the heat processing was performed in the same procedure as invention example 1. Further, the maximum value and the minimum value of the change rate 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 were obtained.
The results are shown in Table 2.

(Evaluation of charge / discharge cycle characteristics)
A cylindrical lithium ion secondary battery shown in FIG. 1 was prepared by the following procedure for the copper foils obtained in the above-described examples and comparative examples, and the cycle life was measured.
(1) A thickener aqueous solution dissolved in 99 parts by weight of water with respect to 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 of carboxymethylcellulose as a thickener. 23 parts by weight was kneaded and dispersed to obtain a negative electrode paste. This negative electrode paste was applied on both sides of a rolled copper foil sample surface to a thickness of 200 μm by a doctor blade method, heated at 200 ° C. for 30 minutes, and dried. After pressurizing to adjust the thickness to 160 μm, the negative electrode plate 6 was obtained by molding by shearing.
(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 PTFE 50% aqueous dispersion as a binder, 41.5% aqueous solution of carboxymethyl cellulose as a thickener A weight part was kneaded and dispersed to obtain a positive electrode paste. This positive electrode paste was applied on both sides to a thickness of about 230 μm by a doctor blade method on a current collector made of an aluminum foil having a thickness of 30 μm, heated at 200 ° C. for 1 hour and dried. After pressurizing and adjusting the thickness to 180 μm, it was molded by shearing to obtain a positive electrode plate 5.
(3) A battery case 8 accommodates an electrode group wound in a spiral shape in a state where the positive electrode plate 5 and the negative electrode plate 6 are insulated through a separator 7 made of a polypropylene resin microporous film having a thickness of 20 μm. .
(4) The negative electrode lead 9 connected from the negative electrode plate 6 was electrically connected through the case 8 and the lower insulating plate 10. Similarly, the positive electrode lead 3 connected from the positive electrode plate 5 was electrically connected to the internal terminal of the sealing plate 1 via the upper insulating plate 4. After these, a non-aqueous electrolyte is injected, and the sealing plate 1 and the battery case 8 are caulked and sealed through the insulating gasket 2 to form a cylindrical lithium ion having a diameter of 17 mm, a height of 50 mm and a battery capacity of 780 mAh. A secondary battery was produced.
(5) The electrolytic solution was obtained by dissolving 1.0 mol of lithium hexafluorophosphate (LiPF ₆ ) as an electrolyte in a mixed solvent of 30% by volume of ethylene carbonate, 50% by volume of ethyl methyl carbonate, and 20% by volume of methyl propionate. A predetermined amount of electrolyte was injected. This electrolytic solution was impregnated in the positive electrode active material layer and the negative electrode active material layer.

  Next, about the battery obtained by said Example and comparative example, the charge / discharge cycle characteristic was evaluated using each 20 batteries.

Therefore, the charge / discharge cycle characteristics were evaluated by repeating a charge / discharge cycle comprising the following charge conditions and discharge conditions in an environment of 20 ° C.
-Charging conditions: Constant current for 2 hours at 4.2V -Constant voltage charging and after 550mA (0.7CmA) constant current charging until the battery voltage reaches 4.2V, the current value further attenuates -Discharge condition: Discharged to a discharge end voltage of 3.0 V at a constant current of 780 mA (1 CmA), and the capacity at the third cycle is the initial capacity. The number of cycles was counted until the discharge capacity decreased to 80% of the initial capacity. Table 3 shows the results of the average number of charge / discharge cycles.

1: Sealing plate 2: Insulating gasket 3: Positive electrode lead 4: Upper insulating plate 5: Positive electrode plate 6: Negative electrode plate 7: Separator 8: Battery case 9: Negative electrode lead 10: Lower insulating plate

Claims (11)

In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy are used as a radiation source before and after heating at any one of 120 ° C., 130 ° C., 150 ° C. and 200 ° C. for 1 hour. An electrolytic copper foil in which the maximum value of the change rate obtained by the following formula is 30% or less with respect to the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100 In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy are used as a radiation source before and after heating at any one of 120 ° C., 130 ° C., 150 ° C. and 200 ° C. for 1 hour. An electrolytic copper foil in which the maximum value of the change rate obtained by the following formula is 10% or less with respect to the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100 In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy are used as a radiation source before and after heating at any one of 120 ° C., 130 ° C., 150 ° C. and 200 ° C. for 1 hour. An electrolytic copper foil in which the maximum value of the change rate obtained by the following formula is 5% or less with respect to the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100 In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy are used as a radiation source before and after heating at any one of 120 ° C., 130 ° C., 150 ° C. and 200 ° C. for 1 hour. Electrolytic copper whose maximum value of the absolute value of the rate of change defined below is 30% or less with respect to the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction Foil.
Here, the maximum value of the absolute value of the change rate 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 obtained by the following equation.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100
Minimum value of rate of change = ((Minimum value of diffraction intensity ratio after heating) − (Diffraction intensity ratio before heating)) / (Diffraction intensity ratio before heating) × 100 In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy are used as a radiation source before and after heating at any one of 120 ° C., 130 ° C., 150 ° C. and 200 ° C. for 1 hour. Electrolytic copper whose maximum value of the absolute value of the rate of change defined below is 10% or less with respect to the diffraction intensity ratio (200) / (111) between (200) plane and (111) plane in X-ray diffraction Foil.
Here, the maximum value of the absolute value of the change rate 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 obtained by the following equation.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100
Minimum value of rate of change = ((Minimum value of diffraction intensity ratio after heating) − (Diffraction intensity ratio before heating)) / (Diffraction intensity ratio before heating) × 100 In an electrolytic copper foil made of copper or a copper alloy, CuKα rays on the surface of the copper or copper alloy are used as a radiation source before and after heating at any one of 120 ° C., 130 ° C., 150 ° C. and 200 ° C. for 1 hour. Electrolytic copper whose maximum value of the absolute value of the rate of change defined below is 5% or less with respect to the diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane in X-ray diffraction Foil.
Here, the maximum value of the absolute value of the change rate 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 obtained by the following equation.
Maximum value of change rate = ((maximum value of diffraction intensity ratio after heating) − (diffraction intensity ratio before heating)) / (diffraction intensity ratio before heating) × 100
Minimum value of rate of change = ((Minimum value of diffraction intensity ratio after heating) − (Diffraction intensity ratio before heating)) / (Diffraction intensity ratio before heating) × 100   The diffraction intensity ratio (200) / (111) between the (200) plane and the (111) plane after heating at 200 ° C for 1 hour is 0.25 to 5.00. The electrolytic copper foil of description. The electrolytic copper foil as described in any one of Claims 1-7 whose minimum value of the rate of change calculated | required by the following formula | equation is a negative value about the said diffraction intensity ratio (200) / (111).
Minimum value of rate of change = ((Minimum value of diffraction intensity ratio after heating) − (Diffraction intensity ratio before heating)) / (Diffraction intensity ratio before heating) × 100 It is a manufacturing method of the electrolytic copper foil as described in any one of Claims 1-8,
At least 2 ppm of nickel is added to the aqueous solution for electrolysis containing at least a copper source in a mass ratio with respect to the aqueous solution for electrolysis, and electrolysis is performed under foil-making conditions adjusted so that the limiting current density ratio is 0.170 or less. A method characterized by that.   The secondary battery electrical power collector using the electrolytic copper foil as described in any one of Claims 1-8.   The secondary battery which used the electrolytic copper foil as described in any one of Claims 1-8 for the electrical power collector.

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