JP6190646B2 - Copper alloy rolled foil for secondary battery current collector and method for producing the same - Google Patents

Description

  The present invention relates to a rolled copper alloy foil applicable to a current collector for a secondary battery and a method for producing the same, and improves the strength, particularly the strength in the width direction (TD direction) of a long foil strip, and has good conductivity. The present invention relates to a rolled copper alloy foil having improved heat resistance and a method for producing the same.

  A copper foil is used for a current collector of a secondary battery such as a lithium ion battery. A current collector made of copper foil becomes a negative electrode by forming, for example, a carbon-based active material layer on the surface thereof. In such a negative electrode, after the active material is applied to the surface of the current collector, the density of the active material is increased by a roll press. However, in the press using a roll, the copper foil constituting the current collector is deformed. As a result, there arises a problem that the active material falls off or the yield is lowered due to the shape defect. In recent years, the current collector has been made thinner, and this problem has become prominent. For these negative electrode current collectors, copper rolled foils such as electrolytic copper foil, tough pitch copper (TPC), and oxygen-free copper (OFC) are used.

  In response to the recent demand for battery capacity improvement, consideration is being given to changing from conventional carbon-based active materials to active materials such as silicon (Si) -based, tin-based (Sn) -based, and carbon-based and silicon-based or tin-based systems. Has been. However, these new active materials have a problem that they are detached from the current collector during use because the amount of expansion / contraction caused by charging / discharging is larger than that of carbon. This is considered to be one of the causes that the current collector is plastically deformed when the active material expands. In light of further demands for increasing battery capacity in recent years, detachment of the active material is a major cause of capacity reduction. In view of this, since active materials having a large expansion and contraction such as Si-based, Sn-based, and composite materials are expected to be applied, it is particularly important to prevent the active material from being detached.

Further, the expansion and contraction of the current collector and the active material also cause problems with respect to the battery size.
A lithium ion secondary battery is configured by interposing a separator between a sheet-like positive electrode and a negative electrode, and filling the space with an electrolyte. For example, in a cylindrical lithium ion secondary battery, a current collector is formed from a copper foil cut so that the long side is in the rolling direction (RD direction), and a negative electrode is obtained after a predetermined treatment. Then, it combines with a positive electrode material and a separator, and it shape | molds in a cylindrical shape by winding while overlapping in a long side direction. In this case, the permissible range for expansion / contraction in the circumferential direction of the negative electrode (RD direction during foil rolling) is relatively large due to winding. However, since the vertical direction of the cylinder (TD direction during foil rolling) is restricted by the dimensions of the battery case, the allowable range is small. When the expansion is extremely advanced, the distortion of the electrode whose end is constrained becomes large, and the electrode may be broken or short-circuited to fail to function as a battery. Therefore, it is required to improve the strength in the TD direction of the copper foil constituting the current collector.

  Further, in the manufacturing process of the lithium ion secondary battery, a polyimide binder is used to join the active material and the current collector when an Si-based or Sn-based active material is used. Heating at 300 ° C. or higher is necessary for joining. Therefore, the copper foil used for the lithium ion secondary battery is required to have a high yield strength even after heating.

  As described above, since plastic deformation of the copper foil for batteries becomes a problem during the manufacturing process and use, it is required to improve the proof stress as an index of deformation. If the yield strength is improved, it is estimated that the yield stress increases and the range of stress that can be elastically deformed is expanded. However, on the other hand, the strength and conductivity of the copper foil are roughly in a trade-off relationship. Battery copper foils are required to improve strength and conductivity in a well-balanced manner.

  Under such circumstances, a copper alloy rolled foil has attracted attention as a copper foil used for a current collector. In general, a copper alloy rolled foil is superior in strength to an electrolytic copper foil. However, it is difficult to manufacture because the thickness is reduced by rolling.

Several techniques have been proposed for improving the mechanical properties of copper alloy rolled foil (see, for example, Patent Documents 1 to 4).
In Patent Document 1, it is proposed to increase the tensile strength by alloying. If tensile strength is high, it is estimated that the yield stress is also high. Patent Document 2 proposes that the elongation after softening is increased by subjecting the copper alloy foil to a heat treatment at 450 ° C. for 4 hours. Patent Document 3 indicates that the strength can be improved by containing each element of Fe, Ni, Zn, and P. Patent Document 4 proposes a method of increasing the strength of a material by containing a large amount of Zn.

However, in the above cited reference 1, although it is not a description of the proof stress, the tensile strength is 550 MPa or less and could not be further increased. In Patent Document 2, there is no description of the proof stress, and the tensile strength after rolling is 500 MPa or less, and since this is further softened by the heat treatment, the tensile strength was insufficient. In Patent Document 3, both strength and electrical conductivity are improved, but no improvement in strength in the width direction has been reported, and the strength is insufficient because proper aging treatment has not been performed. It is done. Furthermore, heat resistance is not shown, and it is considered low due to heat treatment conditions and the like. In Patent Document 4, it is presumed that the conductivity is remarkably lowered due to a large content of the additive element.
Therefore, these conventional techniques cannot fully satisfy the advanced requirements for the material of current collectors for batteries, particularly secondary batteries.

JP 11-339811 A JP 2003-217595 A JP 2006-49237 A JP 2000-133276 A

The problem of the present invention is that the yield strength in the RD direction can be set to 520 MPa or more, the yield strength in the TD direction can be set to 540 MPa or more, and since these strengths (proof strength) are high, plastic deformation and breakage are difficult. 1 hour) in the RD direction yield strength more than 450 MPa, the heat resistance TD direction yield strength is able to more 470MPa is high, also the secondary battery current collector copper is the conductive rate 80% IACS or more and high conductivity simultaneously It is to provide a rolled alloy foil. In addition, a copper alloy rolled foil for a secondary battery current collector capable of improving yield in the manufacturing process of batteries and the like, and improving product reliability (battery damage prevention, etc.) and electrical characteristics, and a manufacturing method thereof Is to provide.

The above-described problems of the present invention have been realized by the following means.
(1) Zr is 0.01 to 0.18 mass%, and Cr is 0.02 to 0.1 mass%, Sn is 0.1 mass% or less, Zn is 0.1 mass% or less, Si is 0.005 to 0.2 mass%, and Mn is 0.03 mass%. Hereinafter, Mg 0.05 mass% or less and P 0.01 mass% or less, containing at least one selected from the group consisting of Cr, Sn, Zn, Si, Mn, Mg and P in total 0 to 0.8 mass%, the balance Is a rolled foil of a Cu-Zr-based copper alloy consisting of copper and inevitable impurities,
Regarding the crystal orientation of the copper alloy rolled foil, the orientation is Brass orientation {110} <112>, Copper orientation {121} <111>, S orientation {231} <346>, Goss orientation {110} <001>. the crystal orientation density, respectively, B, when C, S, and G, [B / C / ( G + S)] is 0.16 to 0.6 der is, the rolling direction and the direction parallel 0.2 % Yield strength is 520 MPa or more, 0.2% yield strength in the direction parallel to the width direction is 540 MPa or more, and 0.2% yield strength in the direction parallel to the rolling direction is 450 MPa or more after heating to 300 ° C. or less within 1 hour of heating time. , a 0.2% yield strength in the width direction parallel to the direction 470MPa or more and a conductivity of Ru der 80% IACS or more secondary battery current collector copper alloy rolled foil.
(2) The secondary battery current collector according to (1), which contains at least one selected from the group consisting of Cr, Sn, Zn, Si, Mn, Mg and P in a total amount of 0.001 to 0.8 ass%. Copper alloy rolled foil .
(3 ) 0.01 to 0.18 mass% of Zr, and 0.02 to 0.1 mass% of Cr , 0.1 mass% or less of Sn, 0.1 mass% or less of Zn, Si 0.005 to 0.2 mass%, Mn 0.03 mass% Hereinafter, Mg 0.05 mass% or less and P 0.01 mass% or less, containing at least one selected from the group consisting of Cr, Sn, Zn, Si, Mn, Mg and P in total 0 to 0.8 mass%, the balance Is a method for producing a copper alloy rolled foil for a secondary battery current collector comprising a Cu-Zr-based copper alloy comprising copper and inevitable impurities,
A homogenization heat treatment step of performing a homogenization heat treatment on the material to be rolled obtained by casting the copper alloy;
A hot rolling process in which hot rolling is performed on the material subjected to homogenization heat treatment,
After the hot rolling step, a cooling step of cooling at a cooling rate of 20 ° C / second or more at least between 600 ° C and 200 ° C;
A chamfering step for chamfering after the cooling step;
An intermediate cold rolling step of performing intermediate cold rolling at a processing rate of 50 to 98% after the chamfering step;
A final recrystallization heat treatment step of performing a recrystallization heat treatment at 500 to 800 ° C. for 10 seconds to 5 hours after the intermediate cold rolling;
After the final recrystallization heat treatment, a final cold rolling step for performing final cold rolling at a processing rate of 90% or more,
I have a,
Regarding the crystal orientation of the copper alloy rolled foil, the orientation is Brass orientation {110} <112>, Copper orientation {121} <111>, S orientation {231} <346>, Goss orientation {110} <001>. When the crystal orientation densities are B, C, S, and G, respectively, [B / C / (G + S)] is 0.16 to 0.6, which is 0.2% in the direction parallel to the rolling direction. The yield strength is 520 MPa or more, the 0.2% yield strength in the direction parallel to the width direction is 540 MPa or more, and the 0.2% yield strength in the direction parallel to the rolling direction is 450 MPa or more after heating to 300 ° C. or less within 1 hour of heating time, A method for producing a copper alloy rolled foil for a secondary battery current collector , wherein the 0.2% yield strength in the direction parallel to the width direction is 470 MPa or more and the conductivity is 80% IACS or more .
( 4 ) The copper alloy contains 0.001 to 0.8 ass% in total of at least one selected from the group consisting of Cr, Sn, Zn, Si, Mn, Mg and P. ( 3 ) Of manufacturing a copper alloy rolled foil for a secondary battery current collector .

  The copper alloy rolled foil for a secondary battery current collector of the present invention has a mechanical strength of a copper alloy rolled foil of a Cu-Zr-based copper alloy, particularly 0.2% proof stress (hereinafter simply referred to as “ (It is also called “Yield strength in the width direction” and “YS (TD)”), and when used as a current collector against external force in the manufacturing process of secondary batteries and the like, it prevents plastic deformation and breakage. In addition, even when an active material is applied, the active material can be prevented from falling off from the current collector. Moreover, since electroconductivity is also excellent, the capacity | capacitance of a secondary battery can be improved and charging / discharging cycling characteristics can be improved. Furthermore, since it has sufficiently high heat resistance, a binder such as polyimide can be used, and it becomes possible to improve the battery characteristics by improving the adhesion between the active material and the current collector.

It is a perspective view which shows typically the copper alloy rolled foil of this invention. It is a figure for demonstrating the manufacturing process of the copper alloy rolling foil of this invention. It is a figure which shows the relationship between [B / C / (G + S)] and the yield strength of a RD sample and a TD sample. It is a figure which shows the relationship between [B / C / (G + S)] and the yield strength of RD sample and TD sample after heating at 300 degreeC for 1 hour.

The first aspect of the present invention is, in a preferred embodiment, a copper alloy rolled foil for a secondary battery current collector made of a copper alloy having the predetermined alloy composition formed by rolling, and the Brass orientation {110} <112>, Copper azimuth {121} <111>, S azimuth {231} <346>, and Goss azimuth {110} <001>, where the crystal orientation density is B, C, S, G, respectively. [B / C / (G + S)] is 0.16 to 0.6.
Here, B / C / (S + G) = B / {C * (S + G)}, the numerator is B, and the denominator is C * (S + G).
Here, the crystal orientation density is the degree of integration of crystal orientations obtained by ODF analysis of the measurement result by X-ray diffraction pole measurement.

2nd of this invention is a manufacturing method of the copper alloy rolling foil which manufactures said copper alloy rolling foil in preferable embodiment, Comprising: The homogenization heat treatment process of performing the homogenization heat processing with respect to the cast to-be-rolled material And a hot rolling step in which hot rolling is performed on the material subjected to homogenization heat treatment, and after the hot rolling step, cooling is performed at a predetermined cooling rate at least between 600 ° C. and 200 ° C. (for example, water cooling) ), A chamfering process for chamfering after the cooling process, an intermediate cold rolling process for performing intermediate cold rolling at a processing rate of 50 to 98% after the chamfering process, and the intermediate cold A final recrystallization heat treatment step for performing recrystallization heat treatment at 500 to 800 ° C. for 10 seconds to 5 hours after rolling, and a final cold rolling for performing final cold rolling at a processing rate of 90% or more after the final recrystallization heat treatment step. Rolling process.

  In the cooling step, the cooling rate between 600 ° C. and 200 ° C. during temperature reduction is set to at least 20 ° C./second or more. This cooling process is performed by water cooling, for example.

  The recrystallization heat treatment step is performed by holding at a heat treatment temperature of 500 ° C. to 800 ° C. for 10 seconds to 5 hours.

In the final cold rolling step, the total processing rate is preferably 90% or more. Here, the total processing rate is a value expressed in% as a ratio obtained by dividing the total thickness reduction (mm) by the final cold rolling of a plurality of passes by the thickness (mm) before the final cold rolling. . If machining is performed in one pass, the total machining rate means the machining rate per one pass.
In addition, the processing rate in each rolling process (also referred to as a plate thickness reduction rate) is the following formula using a plate thickness t ₁ (mm) before the rolling step and a plate thickness t ₂ (mm) after the rolling step. The value calculated as
Processing rate (%) = {(t ₁ −t ₂ ) / t ₁ } × 100

The copper alloy used for the copper alloy rolled foil for the secondary battery current collector of the present invention is a Cu-Zr-based copper alloy containing Zr as an essential component, and the essential component Zr is 0.01 to 0.18 mass%. contains.
In addition to the essential component Zr, the copper alloy used for the Cu-Zr-based copper alloy rolled foil includes Cr 0.02 to 0.1 mass%, Sn0.1 mass% or less, Zn0.1 mass% as a secondary additive component. Hereinafter, Si 0.005 to 0.2 mass%, Mn 0.03 mass% or less, Mg 0.05 mass% or less and P0.01 mass% or less, and at least selected from the group consisting of Cr, Sn, Zn, Si, Mn, Mg and P One kind may be contained in total in an amount of 0.001 to 0.8 mass%, preferably 0.01 to 0.7 mass%.
Note that, in the Cu-Zr-based copper alloy rolled foil, the remainder excluding essential components, or the remainder excluding essential components and sub-addition components is formed of inevitable impurities and copper.

  Here, the contents of the essential component and the auxiliary additive component are not only those added from the outside, but also the amounts that are mixed from the beginning in the raw material of the alloy. Inevitable impurities are generally present in raw materials in metal products, or are inevitably mixed in the manufacturing process. It is an acceptable impurity because it has no effect.

  Further, a preferred embodiment of the invention will be described with reference to the drawings.

  FIG. 1 is a perspective view schematically showing a copper alloy rolled foil (1) of the present invention. Since the copper alloy rolled foil is usually manufactured by repeating rolling with a rolling roll from one direction, there is a difference in characteristics such as strength (difference) between the rolling direction (RD direction) and the width direction (TD direction) of the rolled foil. Direction) may occur. Therefore, in the present invention, in order to examine the anisotropy in the RD direction and the TD direction, the RD sample 2 for measuring the strength by applying stress to the RD direction of the copper alloy rolled foil 1, and the copper alloy rolled foil 1 And a TD sample 3 for measuring the strength by applying stress in the TD direction. In this specification, for example, when the RD sample 2 is measured for proof strength in the RD direction of the copper alloy rolled foil, it is expressed as “proof strength (RD)”, and when the TD sample 3 is measured for proof strength in the TD direction, It will be expressed as “proof strength (TD)”.

The copper alloy rolled foil 1 of the present invention is formed with the following characteristics, for example, a foil thickness t is set to 20 μm or less. The foil thickness t is the thickness of the copper alloy rolled foil 1 as shown in FIG.
In the copper alloy rolled foil of the present invention, the relationship [B / C / (G + S)] of the Copper orientation, the Goss orientation, and the S orientation with respect to the abundance of the Brass orientation with respect to the crystal orientation is 0.16 to 0.00. 6.
The crystal orientation density can be obtained by ODF analysis of a positive pole figure obtained by X-ray diffraction pole figure measurement.
Moreover, the copper alloy rolled foil of the present invention is formed as a copper alloy having a predetermined composition as shown below.

FIG. 2 is a view for explaining a production process of the copper alloy rolled foil of the present invention.
As shown in FIG. 2, the copper alloy rolled foil is manufactured by performing processing and heat treatment with the first step ST1 to the ninth step ST9 as basic steps.

The first step ST1 is a melting step for melting the raw material of the copper alloy, the second step ST2 is a casting step for casting the melted raw material to form a material to be rolled (ingot), and the third step ST3 is a step to be covered. This is a homogenization heat treatment step that is a heat treatment for homogenizing the cast structure of the rolled material. This homogenization heat treatment process is performed at 800-1000 degreeC for 0.1 to 5 hours.
The fourth step ST4 is a hot rolling step. Hot rolling refers to rolling performed by heating a metal to a recrystallization temperature or higher (usually 600 ° C. to 1000 ° C. for the copper alloy in the present invention).
The fifth step ST5 is a cooling step, the sixth step ST6 is a chamfering step for removing oxide scale, the seventh step ST7 is an intermediate cold rolling step, and the eighth step ST8 is for recrystallization. The ninth step ST9 is a final cold rolling step. Note that cold rolling refers to rolling performed in a temperature range (for example, room temperature) where recrystallization does not occur.
Further, an intermediate annealing step ST7 ′ may be performed before the intermediate cold rolling step ST7. Alternatively, the intermediate cold rolling step ST7 may be repeated until the desired plate thickness, and the intermediate annealing step ST7 ′ may be performed between the intermediate cold rolling steps ST7. In this latter case, the intermediate annealing step ST7 ′ may or may not be performed before the first intermediate cold rolling step ST7.
The heat treatment conditions in the intermediate annealing step ST7 ′ are preferably a heating temperature of 500 to 800 ° C. and a heating time of 10 seconds to 5 hours.

Specific processing and heat treatment from the first step ST1 to the ninth step ST9 and their conditions will be described later.
The characteristic treatment for producing the copper alloy rolled foil of the present invention is that the cooling rate during cooling is at least 20 ° C./second during the cooling step, and the heat treatment in the recrystallization heat treatment step. The heating temperature of 500 ° C. to 800 ° C. is maintained at that temperature for 10 seconds to 5 hours, and the processing rate in the final cold rolling step is 90% or more.
Here, although cooling of 5th process ST5 is implemented from rolling completion temperature to about 40 degreeC, in this invention, the cooling rate in the said predetermined temperature range 600 degreeC-200 degreeC in the middle of the cooling (temperature reduction) If desired, a desired crystal orientation density can be obtained. This is because the effect of the cooling rate on the control of crystal orientation is small in the higher and lower temperature regions.

  Hereinafter, the copper alloy rolled foil of the present invention will be described in detail with respect to the above-mentioned crystal orientation density, yield strength, electrical conductivity, heat resistance, manufacturing process for controlling the crystal orientation, and characteristics such as alloy components. This example will be described in comparison with a comparative example.

The crystal orientation display method in this specification uses a rectangular coordinate system in which the rolling direction (RD) of the material is the X axis, the sheet (foil) width direction (TD) is the Y axis, and the rolling normal direction (ND) is the Z axis. Using the index (hkl) of the crystal plane in which each region in the material is perpendicular to the Z axis (parallel to the rolling surface) and the index [uvw] of the crystal direction parallel to the X axis, (hkl) [ uvw]. In addition, as in (132) [6-43] and (231) [3-46], for equivalent orientations under the copper crystal cubic symmetry, parentheses representing the family are used, {Hkl} <uvw>.
For example, the Brass orientation is a state in which the {110} plane faces the rolling surface normal direction (ND) and the <112> direction faces the rolling direction (RD), and is indicated by an index of {110} <112>. It is.

[Crystal orientation density]
In a normal copper alloy rolled foil, a rolling texture is developed. For the problem of strength reduction, the rolling texture (rolling stable orientation) of a general copper alloy has a certain spread, but the Brass orientation {110} <112>, Copper orientation {121} <111> , S orientation {231} <346> is common, and Goss orientation {110} <001> also exists.
Some of these crystal orientations have strength anisotropy, and the Brass orientation improves the tensile strength in the direction perpendicular to the rolling direction, while the Copper orientation increases the strength in the direction parallel to the rolling direction. . On the other hand, the Goss direction and the S direction give the same strength in any direction.

In the copper alloy rolled foil of the present invention, it was confirmed that the strength was increased by increasing the volume oriented in the Brass direction in the material, and in particular, the strength in the TD direction perpendicular to the rolling direction was improved.
The inventors orientated the crystal orientation density oriented in the Brass orientation as B, the crystal orientation density oriented in the Copper orientation as C, and the crystal orientation density oriented in the S orientation as S or Goss orientation. It has been found that it is effective to increase [B / C / (G + S)] when the crystal orientation density is G. This relationship will be described below with reference to the results of Examples and Comparative Examples described later.

FIG. 3 shows [B / C / (G + S)] and the proof stress of a sample (RD sample) taken in the longitudinal direction parallel to the rolling direction and a sample taken in the width direction perpendicular to the rolling direction (TD sample). It is a figure which shows a relationship. A normal Cu—Zr-based alloy has a yield strength in the RD direction of less than 520 MPa and a yield strength in the TD direction of less than 540 MPa. On the other hand, in the copper alloy rolled foil of the present invention, it was confirmed that the yield strength in the RD direction can be improved to 520 MPa or more and the yield strength in the TD direction can be improved to 540 MPa or more.
As can be seen from FIG. 3 (and Table 1), in Examples 1 to 7 in which [B / C / (G + S)] is 0.16 to 0.6, the proof stress (TD) is 540 MPa or more. Furthermore, it was excellent also in yield strength (RD) and heat resistance (RD and TD) described later.

On the other hand, in Comparative Examples 3 and 5 and Reference Examples 1 and 2 in which [B / C / (G + S)] is less than 0.16, the yield strength (TD) is less than 540 MPa, which is inferior. Both are inferior in yield strength (RD) and heat resistance (TD and RD). Furthermore, in Comparative Example 3, the conductivity is inferior. In Comparative Example 4 where [B / C / (G + S)] is less than 0.16, the yield strength (RD) is inferior and the heat resistance (RD and TD) is also inferior. Further, in Comparative Example 1 in which [B / C / (G + S)] is 0.16 to 0.6, the alloy composition is out of the range defined in the present invention in that the total content of the auxiliary additive elements is too large. The proof stress and heat resistance are satisfactory, but the electrical conductivity is inferior. In Comparative Example 2 having [B / C / (G + S)] of 0.16 to 0.6, the alloy composition is outside the range defined in the present invention in that the content of Zr, which is an essential element, is too large. It is inferior in electrical conductivity, and inferior in yield strength (TD and RD) and heat resistance (RD). Further, Comparative Example 6 having [B / C / (G + S)] of 0.16 to 0.6 is outside the range defined by the present invention in terms of not containing Zr, and the proof stress (TD and RD). ) And heat resistance (RD and TD).
That is, as shown in FIG. 3, by forming a copper alloy rolled foil so as to have a predetermined alloy composition and [B / C / (G + S)] of 0.16 to 0.6, conductivity is improved. While maintaining the above, the proof stress in the RD and TD directions can be improved, and the heat resistance can also be improved.

FIG. 4 is a diagram showing the relationship between [B / C / (G + S)] and the yield strength (heat resistance) of the RD sample and TD sample after heating the material at 300 ° C. for 1 hour. The copper alloy rolled foils of the present invention were all excellent in heat resistance because the proof strength in the RD direction after heating was 450 MPa or higher and the proof strength in the TD direction after heating was improved to 470 MPa or higher.
As can be seen from FIG. 4 (and Table 1), in Examples 1 to 7 where [B / C / (G + S)] is 0.16 to 0.6, the yield strength (TD) after the heat treatment is 470 MPa or more. is there. Furthermore, it was excellent also in the yield strength (RD) after heat processing.
On the other hand, in Comparative Examples 3 to 5 and Reference Examples 1 and 2 where [B / C / (G + S)] is less than 0.16, the yield strength (TD) after heat treatment is as low as less than 470 MPa. In addition, all are inferior in yield strength (RD) after heat processing. Moreover, in Comparative Examples 2 and 6 having [B / C / (G + S)] of 0.16 to 0.6, the proof stress (RD) after the heat treatment is low. In addition, in Comparative Example 6, the yield strength (TD) after the heat treatment is low. Furthermore, although Comparative Example 1 with [B / C / (G + S)] of 0.16 to 0.6 satisfies the proof stress after the heat treatment, the total content of the secondary additive elements is too large. Inferior conductivity.
That is, as shown in FIG. 4, by forming a copper alloy rolled foil so as to have a predetermined alloy composition and [B / C / (G + S)] of 0.16 to 0.6, the conductivity is increased. Can be maintained, the yield strength can be improved, and the yield strength (heat resistance) in the RD and TD directions after heating can be further improved.

According to the present invention, when the predetermined alloy composition is [B / C / (G + S)] is 0.16 to 0.6, the conductivity is excellent as 80% IACS or more as described later. It was.
In other words, by forming a copper alloy rolled foil so as to have a predetermined alloy composition and [B / C / (G + S)] of 0.16 to 0.6, high strength, heat resistance, and conductivity are achieved. Can be obtained at the same time, and as a result, excellent battery characteristics can be obtained.
In the present invention, [B / C / (G + S)] is 0.16 to 0.6, preferably 0.18 to 0.4, and more preferably 0.2 to 0.3.

  For the analysis of the crystal orientation in the present invention, X-ray diffraction pole figure method and ODF analysis are used. ODF is an abbreviation for Crystal Orientation Distribution Function (Crystal Orientation Distribution Function), which is a crystal orientation analysis technique that quantifies the abundance of textures by combining the three-dimensional positive map of each crystal orientation. .

  The texture orientation density referred to in the present invention is the ratio of the strength of each orientation to a random orientation. The term “random” as used herein means a texture in which crystal orientations are uniformly dispersed and do not accumulate, and the orientation density (accumulation strength) on the ODF diagram is equal to 1. Regarding the definition of random orientation, Japanese Patent Laid-Open No. 2008-303455 also has a similar description. Further, a value with an orientation density of 1 or less means that the orientation appears with a very low probability.

  In the ODF analysis, three variables of Euler angles (φ1, Φ, φ2) are displayed in a three-dimensional azimuth space having a rectangular coordinate axis. The angle range to be displayed depends on the symmetry of the crystal and the symmetry of the pole figure, and φ1 can take a value of 0 ° to 360 °, but the pole figure has symmetry vertically and horizontally like a rolled plate. In the case where a 1/4 pole figure can be displayed, φ1 is in the range of 0 ° to 90 °, and Φ is also in the range of 0 ° to 90 °. The range of φ2 depends on the crystal system, and since the cubic system has a 4-fold symmetry axis, the range of 0 ° to 90 ° is generally displayed. ODF should be displayed three-dimensionally originally, but it is difficult to display accurately with an iso-density curved surface, so a two-dimensional cross section with constant φ2 or φ1 can be displayed at an appropriate interval (usually at an interval of 5 °). Many. Since a point given by a set of Euler angles (φ1, Φ, φ2) represents one azimuth, the priority azimuth can be accurately determined by reading the Euler angle at the position where the ODF shows a maximum value. Since the texture is quantitatively discussed by the ODF analysis as described above, the texture can be quantified by analyzing the three-dimensional information from a plurality of pole figures (two-dimensional information) using the orientation distribution function.

  As a method of obtaining a pole figure for performing ODF analysis, there are an X-ray pole figure method and an electron backscatter diffraction image method (EBSD method). The EBSD method is an abbreviation for Electron Back Scatter Diffraction. In the X-ray pole figure method, an X-ray incident angle with respect to a sample is fixed to a specific Bragg angle (for example, 111 diffraction angle), and a pole figure is obtained by systematically rotating the sample around two orthogonal axes.

  In the EBSD method, an electron beam is incident on one point on the surface of a sample in a scanning electron microscope (SEM), and the crystal orientation and crystal structure of a local region are analyzed using a reflected electron diffraction pattern (electron back-scattering pattern). How to do.

  The orientation density in the present invention is measured by using RINT2500 (trade name) manufactured by Rigaku Co., Ltd. as an X-ray diffractometer in the above X-ray pole figure method, tube voltage: 50 kV, tube current: 100 mA, and diverging slit: 0.5. °, scattering slit: 7 mm, light receiving slit: 7 mm, divergence length limiting slit: 1.2 mm, scanning speed: 360 ° / min, step width: 5 ° The range of 2θ in which the diffraction intensity was measured on each surface (θ is the diffraction angle) is (111): 38.0 to 48.0 °, (200): 45.0 to 55.0 °, (220): 69. 0.0 to 79.0 °.

  On the other hand, in the EBSD method, an electron beam irradiated to the sample and inelastically scattered in the vicinity of the surface of the sample has a pair of diffraction lines that satisfy the conditions of Bragg reflection with respect to a specific crystal lattice plane. Form. An EBSD pattern is obtained by projecting a part of this diffraction line on a screen. OIM-A5 (trade name) manufactured by TSL Solutions Co., Ltd. was used as an EBSD analyzer.

[Strength]
The negative electrode current collector material for a battery, yield strength (RD) is Ru der least 520 MPa. Good Mashiku is 530MPa or more, and more preferably not less than 540 MPa. The TD direction yield strength Ri der than 540 MPa, good Mashiku is 550MPa or more, and more preferably not less than 560 MPa. Here, the yield strength is defined as a stress that gives a permanent strain of 0.2%.

[Heat-resistant]
The negative electrode current collector material for a battery, the following 300 ° C. As the heat resistance after heating within one hour Strength (RD) is Ru der least 450 MPa. Good Mashiku is 460MPa or more, and more preferably not less than 470 MPa. Ri der yield strength after the heating is more than 470MPa in TD direction is preferably at least 480 MPa, more preferably 490MPa or more. Here, the heat resistance is defined as a yield strength after heating at 300 ° C. for 1 hour, that is, a stress giving a permanent strain of 0.2%. That is, the evaluation is performed on the sample after the heat treatment of “300 ° C., 1 hour” under the condition of “300 ° C. or less, within 1 hour” under the maximum heat load.

[Conductivity]
The negative electrode current collector material for a battery, conductivity Ru der 80% IACS or more. Good Mashiku is 82% IACS or more, more preferably 85% IACS or more.

[Process for controlling crystal orientation]
In general, in a copper alloy, if a cubic texture is developed, the region in which the (100) plane is oriented in the rolling direction can be increased and the strength can be improved.
However, the cubic texture develops by recrystallization and cannot be increased into a processed structure such as a copper alloy rolled foil. In order to improve the strength, work hardening by rolling is indispensable, and the technique of applying the recrystallization priority orientation by annealing the foil cannot be applied.

  The example of the manufacturing process for controlling to the crystal orientation in which effectiveness was found in this invention is shown. As described above, the crystal orientation density oriented in the Brass orientation {110} <112>, Copper orientation {121} <111>, S orientation {231} <346>, and Goss orientation {110} <001>. And B, C, S, and G, respectively, as long as the value of [B / C / (G + S)] satisfies the relationship of 0.16 to 0.6, a specific example of the manufacturing process shown here It is not limited to only.

As a manufacturing process of the copper alloy rolled foil for controlling the crystal orientation, as shown in FIG. 2, the first process ST1 to the ninth process ST9 are the basic processes.
That is, the melting step in the first step ST1, the casting step in the second step ST2, the homogenization heat treatment step in the third step ST3, the hot rolling step in the fourth step ST4, the cooling step in the fifth step ST5, and the sixth step ST6. The manufacturing process is basically composed of the chamfering step, the intermediate cold rolling step of the seventh step ST7, the recrystallization heat treatment step of the eighth step ST8, and the final cold rolling step of the ninth step ST9.
Here, as described above, the intermediate cold rolling step ST7 may be repeated to a desired plate thickness, and the intermediate annealing step ST7 ′ may be performed between the intermediate cold rolling steps ST7.

  The manufacturing method of the present invention is characterized by a cooling rate of 20 ° C./second or more while the temperature is lowered from at least 600 ° C. to 200 ° C. in the cooling step ST5, and a heat treatment temperature in the recrystallization heat treatment step ST8 of 500 to 800 ° C. And the processing rate in the final cold rolling step ST9 is 90% or more.

[Alloy composition]
The range of the content of the essential component Zr contained in the Cu-Zr alloy is 0.01 to 0.18 mass % .
In addition to the above essential component Zr, addition of at least one sub-added element selected from Cr, Sn, Zn, Si, Mn, Mg and P is allowed for the purpose of further improving the strength and heat resistance. . The details of the content of the auxiliary additive element are as described above.
In particular, in the case of rolling up to a foil having a thickness of 20 μm or less, for the problem that pinholes are generated due to the inherent second phase, the melt is deoxidized by adding Si, Mg, P, etc. to form an oxide. It is effective to suppress the formation of sulfide by addition of Mn.

When added exceeding the upper limit of the components specified above, it is dispersed as a coarse second phase of submicron order in the form of oxide, precipitate, crystallized product, etc., up to a foil thickness of 20 μm or less This is not preferable because it causes pinholes and foil (plate) breakage during rolling. Further, it is not preferable because the conductivity is remarkably lowered.
Moreover, when it adds below the lower limit of the component prescribed | regulated above, the addition effect is not fully acquired. The addition amount of each component is appropriately adjusted within the predetermined range in accordance with the above and below uses.

The proof stress of the Cu-Zr-based copper alloy used for the rolled copper alloy foil of the present invention is 520 MPa or more in the RD direction and 540 MPa or more in the TD direction. Further, the conductivity is 80% or more of IACS (International Annealed Copper Standard), and the electrical characteristics are also good.
Here, 80% IACS means that when a standard annealed copper wire with an electrical resistivity of IACS (International Annealed Copper Wire Standard) is 100%, the conductor made of the target copper alloy is 80% conductive. It shows that it has sex.

  The copper alloy rolled foil of the present invention is particularly intended for a copper alloy foil having a thickness of 20 μm or less, but can also be applied to a copper alloy foil having a thickness exceeding 20 μm. Although there is no restriction | limiting in particular in the minimum of thinness, Usually, it is about 3 micrometers.

  The copper alloy rolled foil for the secondary battery current collector of the present invention can also be applied as a negative electrode current collector of a battery, for example, not only the above carbon-based and silicon-based negative electrode active materials, but also tin-based, It can be suitably used as a negative electrode current collector of a battery in which various active materials such as a composite system of these are provided thereon. The effects of the present invention are not limited to the battery configuration shown in this document.

The copper alloy rolled foil of the present invention can also be used for flexible substrates (FPC), tape carrier packages (TCP, TAB), and chip-on-flex (COF).
However, the scope of the present invention is a copper alloy rolled foil having a thickness of 20 μm or less.

Specific examples of the present invention will be described below.
The results of the examples are shown in Table 1 below.
In Table 1, the evaluation result of the Example of the said copper alloy rolled foil was shown in contrast with the comparative example.
Before describing the result evaluation of the examples in Table 1, the method for producing the copper alloy rolled foils of the examples of the present invention and the comparative examples will be described.

[Manufacturing method of copper alloy rolled foil]
The Example of the manufacturing method of the copper alloy rolled foil of this invention is described with reference to FIG.
In the first step ST1, the raw material was melted in a high-frequency melting furnace, and the melted raw material was cast in the second step ST2 at a cooling rate of 0.1 to 100 ° C./second to obtain an ingot. The ingot contained the alloy components shown in Table 1, and the remainder was formed of Cu and inevitable impurities.

In the third step ST3, the ingot obtained in the second step ST2 is subjected to a homogenization heat treatment at a temperature of 800 to 1000 ° C. for 0.1 to 5 hours, and then hot-rolled at a temperature of 600 to 1000 ° C. as it is in the fourth step ST4. Went. Here, the temperature range 600 to 1000 ° C. of hot rolling is a temperature range from the start to the end of hot rolling. The processing rate was 85 to 97%.
Next, in 5th process ST5, it cooled by water cooling at the cooling rate of at least 600 to 200 degreeC at 20 degree-C / sec or more, and chamfered in order to remove an oxide scale in 6th process ST6.

Thereafter, in the seventh step ST7, intermediate cold rolling with a processing rate of 50 to 98% is performed, and in the eighth step ST8, a recrystallization heat treatment is performed at 500 to 800 ° C. for 10 seconds to 5 hours. In step ST9, final cold rolling was performed at a processing rate of 90% or more to produce a copper alloy rolled foil having a foil thickness of 20 μm or less.
After each heat treatment and rolling, acid cleaning and surface polishing were performed according to the state of oxidation and roughness of the material surface, and correction with a tension leveler was performed according to the shape.
Among these manufacturing conditions, in each test example, the cooling rate (° C./second) between 600 ° C. and 200 ° C. in the fifth step ST5, the aging heat treatment temperature (° C.) in the eighth step ST8, the ninth step Table 1 shows the processing rate (thickness reduction rate,%) in ST9.

  The following evaluation was performed on this copper alloy rolled foil. The evaluation results are also shown in Table 1.

[Crystal orientation density [B / C / (G + S)]]
The crystal orientation densities oriented in the Brass orientation {110} <112>, Copper orientation {121} <111>, S orientation {231} <346>, and Goss orientation {110} <001> are respectively B, C, and S. , G, and [B / C / (G + S)] represented by these were measured by the X-ray diffraction pole figure measurement method and the ODF analysis method according to the method described above.
By the ODF analysis method described above, the crystal orientation density was analyzed using the crystal orientation analysis technique using the positive electrode diagram obtained by the X-ray diffraction pole figure measurement.

[0.2% yield strength (YS)]
As shown in FIG. 1, RD sample (2) and TD sample (3) are collected from each copper alloy rolled foil (1) obtained above, and 0.2% yield strength (YS) is obtained for these samples. , Measured by a tensile test according to JIS Z2241. In this tensile test, a tension is applied to the RD sample in a direction parallel to the rolling direction (RD direction), while a tension is applied to the TD sample in a direction perpendicular to the rolling direction (TD direction). I went.
The yield strength is 520 MPa or more for the RD sample and 540 MPa or more for the TD sample, and less than that is rejected.

[Heat-resistant]
About each RD sample and TD sample of each copper alloy rolled foil obtained above, after performing a heat treatment that is held at 300 ° C. for 1 hour in an Ar atmosphere, a tensile test is performed by the same method (JIS Z2241) as before heating. And 0.2% proof stress (YS) was measured. It means that heat resistance is so excellent that there is little fall of the yield strength after heat processing.
As for heat resistance, the proof stress after heat treatment is 450 MPa or more for the RD sample and 470 MPa or more for the TD sample, and each less than that is rejected. It should be noted that a material that passes the heat treatment at 300 ° C. for 1 hour means that the heat treatment is performed at 300 ° C. or less for 1 hour in the same manner.

[Conductivity (EC)]
The specific resistance was measured by a four-terminal method in a constant temperature bath maintained at 20 ° C. (± 0.5 ° C.) to calculate the conductivity. In addition, the distance between terminals was 100 mm.
The electrical conductivity is 80% IACS or higher as acceptable, and less than that is rejected.

  In the examples of Table 1, tests and evaluations were performed on Examples 1 to 7 as the copper alloy rolled foils (Examples of the present invention) of the present invention, Comparative Examples 1 to 6 and Comparative Examples 1 to 2 as comparative examples, respectively. .

Examples 1 to 7 according to the present invention and Comparative Examples 3 to 5 for comparison satisfy the condition that the essential component Zr is contained in an amount of 0.001 to 0.4 mass%, and are sub-addition components. When Cr, Sn, Zn, Si, Mn, Mg, and P are contained, the condition that the total content is 0.001 to 0.8 mass% is satisfied. Here, as for Examples 1-7, the manufacturing conditions satisfy the conditions which this invention prescribes | regulates. On the other hand, in Comparative Examples 3 to 5, the production conditions do not satisfy the conditions defined by the present invention.
On the other hand, Comparative Examples 2 and 6 and Reference Examples 1 and 2 do not satisfy the condition of setting the essential component Zr to a content of 0.001 to 0.4 mass%. In Comparative Example 1, when the auxiliary additive components Cr, Sn, Zn, Si, Mn, Mg, and P are contained, the total content of 0.001 to 0.8 mass% is not satisfied.

  In Examples 1 to 7, [B / C / (G + S)] satisfies the condition of 0.16 to 0.6. Examples 1-7 both have high yield strength (RD) and yield strength (TD), and also have good heat resistance (both RD and TD), and also have high electrical conductivity (EC). Therefore, it can be said that in each of the examples, high strength (yield strength), heat resistance and conductivity were achieved at the same time.

  On the other hand, in each of the comparative examples and the reference examples, as described above, at least one of the alloy composition and the manufacturing conditions did not satisfy the predetermined condition of the present invention, and therefore, the result was inferior in any of the characteristics. It became. This will be described in detail below.

Comparative Example 1 is an example in which the content of the auxiliary additive component is too much. And the comparative example 1 has low electrical conductivity. Thus, Comparative Example 1 is inferior in conductivity to the inventive example. This is presumably due to the fact that the total content of the auxiliary additive components is too large.
That is, it is presumed that the electrical conductivity is low unless the total content of the sub-addition components for obtaining a predetermined alloy composition, which is one of the characteristics of the copper alloy rolled foil of the present invention, is controlled. .

Comparative Example 2 is an example in which the content of the essential component Zr is too large. And the comparative example 2 has low electrical conductivity, and furthermore, YS (RD) and YS (TD), that is, strength, and YS (RD) after heating, that is, heat resistance, are also low. Thus, the comparative example 2 is inferior to the example of this invention in electrical conductivity, intensity | strength, and heat resistance. This is presumably due to the fact that the content of the essential component Zr is too large.
That is, if the content of the essential component Zr for making a predetermined alloy composition, which is one of the features of the copper alloy rolled foil of the present invention, is not controlled, the conductivity, strength and heat resistance are low. Inferred.

In Comparative Example 3, [B / C / (G + S)] is too small to satisfy the condition. And the comparative example 3 has low electrical conductivity, and furthermore, YS (TD) and YS (RD), that is, strength, and YS (TD) and YS (RD), that is, heat resistance after heating are also low. Thus, the comparative example 3 is inferior to the example of this invention in electrical conductivity, intensity | strength, and heat resistance. This is presumably due to the fact that the recrystallization heat treatment temperature is too low.
That is, if the recrystallization heat treatment temperature, which is one of the characteristics of the production method of the present invention, is too low, the condition [B / C / (G + S)] cannot be satisfied, and as a result, the conductivity, strength and heat resistance are reduced. It is presumed that the nature is low.

In Comparative Example 4, [B / C / (G + S)] is too small to satisfy the condition. And the comparative example 4 has low YS (RD), and also YS (TD) and YS (RD) after a heating, ie, heat resistance, are also low. As described above, Comparative Example 4 is inferior in strength and heat resistance to the inventive example. This is presumably due to the fact that the cooling rate after hot rolling is too slow.
That is, if the cooling rate after hot rolling, which is one of the characteristics of the production method of the present invention, is too slow, the condition [B / C / (G + S)] cannot be satisfied, and as a result, strength and heat resistance are reduced. It is presumed that the nature is low.

In Comparative Example 5, [B / C / (G + S)] is too small to satisfy the condition. In Comparative Example 5, YS (TD) and YS (RD) are low, and further, YS (TD) and YS (RD) after heating, that is, heat resistance is also low. Thus, the comparative example 5 is inferior to the example of this invention in intensity | strength and heat resistance. This is presumably due to the fact that the processing rate in the final cold rolling is too low.
That is, if the processing rate in the final cold rolling, which is one of the characteristics of the production method of the present invention, is too low, the condition [B / C / (G + S)] cannot be satisfied, and as a result, the strength and It is assumed that the heat resistance is low.

Comparative Example 6 is an example in which the essential component Zr was not added. And the comparative example 6 has low YS (TD) and YS (RD), and also YS (TD) and YS (RD) after heating, ie, heat resistance, is also low. Thus, Comparative Example 6 is inferior in strength and heat resistance to the present invention example. This is presumably due to the absence of Zr addition.
That is, it is inferred that the strength and heat resistance are low without the addition of Zr for obtaining a predetermined alloy composition, which is one of the characteristics of the copper alloy rolled foil of the present invention.

Reference Example 1 (TFC) is an example in which the essential component Zr is not added, and [B / C / (G + S)] is too small to satisfy the conditions. In Reference Example 1, YS (TD) and YS (RD) are low, and further, YS (TD) and YS (RD) after heating, that is, heat resistance is also low. Thus, the reference example 1 is inferior to the example of this invention in intensity | strength and heat resistance. This is presumably because Zr was not added and the recrystallization heat treatment temperature was too low.
That is, the recrystallization heat treatment temperature is one of the features of the copper alloy rolled foil of the present invention, without Zr addition for obtaining a predetermined alloy composition, and one of the features of the production method of the present invention. If it is too low, the condition [B / C / (G + S)] cannot be satisfied, and as a result, it is presumed that the strength and heat resistance are low.

Reference Example 2 (OFC) is an example in which the essential component Zr was not added, and [B / C / (G + S)] was too small to satisfy the conditions. In Reference Example 2, YS (TD) and YS (RD) are low, and further, YS (TD) and YS (RD) after heating, that is, heat resistance is also low. Thus, the reference example 2 is inferior to the example of this invention in intensity | strength and heat resistance. This is presumably because Zr was not added and the recrystallization heat treatment temperature was too low.
That is, the recrystallization heat treatment temperature is one of the features of the copper alloy rolled foil of the present invention, without Zr addition for obtaining a predetermined alloy composition, and one of the features of the production method of the present invention. If it is too low, the condition [B / C / (G + S)] cannot be satisfied, and as a result, it is presumed that the strength and heat resistance are low.

As described above, a copper alloy rolled foil satisfying that [B / C / (G + S)] is 0.16 to 0.6 with respect to a predetermined alloy composition and crystal orientation density defined in the present invention. In the case of, strength (yield strength), heat resistance and conductivity were all high.
Further, the cooling rate is set to 20 ° C./second or more when the temperature is lowered between at least 600 ° C. and 200 ° C. after the hot rolling specified by the method for producing a copper alloy rolled foil of the present invention, and the recrystallization heat treatment temperature is set to 500 to When [B / C / (G + S)] satisfies the condition of 0.16 to 0.6 by setting the working rate in the final cold rolling to 90% or more at 800 ° C. for 10 seconds to 5 hours In other words, it was possible to obtain a copper alloy rolled foil having high strength (yield strength), heat resistance, and conductivity.

  On the other hand, in the comparative example, the prescribed alloy composition was not satisfied or [B / C / (G + S)] did not satisfy the condition of 0.16 to 0.6. And at least one of the electrical conductivity was inferior without satisfying the predetermined acceptance criteria.

  From the above results, according to the copper alloy rolled foil of the present invention, since the strength (yield strength) is high, it is difficult to be plastically deformed or broken. Furthermore, after 300 ° C. heating (heating time 1 hour), the proof strength can be maintained high and heat resistance Since the conductivity is high and the conductivity is high at the same time, it is possible to improve the yield of the manufacturing process of the battery and the like, reliability (breakage etc.) of the product, and electrical characteristics.

1 Copper alloy rolled foil 2 RD sample 3 TD sample

Claims (4)

Zr is 0.01 to 0.18 mass%, Cr 0.02 to 0.1 mass%, Sn 0.1 mass% or less, Zn 0.1 mass% or less, Si 0.005 to 0.2 mass%, Mn 0.03 mass% or less, Mg0 .05 mass% or less and P0.01 mass% or less, containing at least one selected from the group consisting of Cr, Sn, Zn, Si, Mn, Mg and P in a total of 0 to 0.8 mass%, with the balance being copper and A rolled foil of a Cu-Zr-based copper alloy made of inevitable impurities,
Regarding the crystal orientation of the copper alloy rolled foil, the orientation is Brass orientation {110} <112>, Copper orientation {121} <111>, S orientation {231} <346>, Goss orientation {110} <001>. the crystal orientation density, respectively, B, when C, S, and G, [B / C / ( G + S)] is 0.16 to 0.6 der is, the rolling direction and the direction parallel 0.2 % Yield strength is 520 MPa or more, 0.2% yield strength in the direction parallel to the width direction is 540 MPa or more, and 0.2% yield strength in the direction parallel to the rolling direction is 450 MPa or more after heating to 300 ° C. or less within 1 hour of heating time. , a 0.2% yield strength in the width direction parallel to the direction 470MPa or more and a conductivity of Ru der 80% IACS or more secondary battery current collector copper alloy rolled foil. 2. The copper alloy for a secondary battery current collector according to claim 1, comprising 0.001 to 0.8 mass% in total of at least one selected from the group consisting of Cr, Sn, Zn, Si, Mn, Mg, and P. Rolled foil . Zr is 0.01 to 0.18 mass%, Cr 0.02 to 0.1 mass%, Sn 0.1 mass% or less, Zn 0.1 mass% or less, Si 0.005 to 0.2 mass%, Mn 0.03 mass% or less, Mg0 .05 mass% or less and P0.01 mass% or less, containing at least one selected from the group consisting of Cr, Sn, Zn, Si, Mn, Mg and P in a total of 0 to 0.8 mass%, with the balance being copper and A method for producing a copper alloy rolled foil for a secondary battery current collector made of a Cu-Zr copper alloy made of inevitable impurities,
A homogenization heat treatment step of performing a homogenization heat treatment on the material to be rolled obtained by casting the copper alloy;
A hot rolling process in which hot rolling is performed on the material subjected to homogenization heat treatment,
After the hot rolling step, a cooling step of cooling at a cooling rate of 20 ° C / second or more at least between 600 ° C and 200 ° C;
A chamfering step for chamfering after the cooling step;
An intermediate cold rolling step of performing intermediate cold rolling at a processing rate of 50 to 98% after the chamfering step;
A final recrystallization heat treatment step of performing a recrystallization heat treatment at 500 to 800 ° C. for 10 seconds to 5 hours after the intermediate cold rolling;
After the final recrystallization heat treatment, a final cold rolling step for performing final cold rolling at a processing rate of 90% or more,
I have a,
Regarding the crystal orientation of the copper alloy rolled foil, the orientation is Brass orientation {110} <112>, Copper orientation {121} <111>, S orientation {231} <346>, Goss orientation {110} <001>. When the crystal orientation densities are B, C, S, and G, respectively, [B / C / (G + S)] is 0.16 to 0.6, which is 0.2% in the direction parallel to the rolling direction. The yield strength is 520 MPa or more, the 0.2% yield strength in the direction parallel to the width direction is 540 MPa or more, and the 0.2% yield strength in the direction parallel to the rolling direction is 450 MPa or more after heating to 300 ° C. or less within 1 hour of heating time, A method for producing a copper alloy rolled foil for a secondary battery current collector , wherein the 0.2% yield strength in the direction parallel to the width direction is 470 MPa or more and the conductivity is 80% IACS or more . The secondary according to claim 3 , wherein the copper alloy contains 0.001 to 0.8 ass% in total of at least one selected from the group consisting of Cr, Sn, Zn, Si, Mn, Mg and P. A method for producing a copper alloy rolled foil for a battery current collector .

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