KR20140030062A - Aluminum hard foil for battery collector - Google Patents

Abstract

The present invention provides an aluminum hard foil for a battery current collector which has a proper level of strength, excellent ductility, and low electric resistance. The aluminum hard foil contain 1.4-1.7 mass% of Fe, 0.1-0.5 mass% of Cu, 0.4 mass% or less of Si, the balance of Al, and unavoidable impurities. The size of sub-grains is 0.8 um or less in a thickness direction and 45 um or less in a rolling direction.

Description

Aluminum rigid foil for battery collector {ALUMINUM HARD FOIL FOR BATTERY COLLECTOR}

The present invention relates to an aluminum hard foil for a battery current collector which is used as a positive electrode current collector of a lithium ion secondary battery.

In recent years, lithium ion secondary batteries have been used as power sources for mobile tools such as cellular phones and notebook computers. The electrode material of the lithium ion secondary battery is formed of a cathode material, a separator, and an anode material. In the production of the positive electrode material, an active material such as LiCoO _{2 having a} thickness of about 100 μm is coated on both surfaces of a current collector aluminum foil (or aluminum alloy foil) having a thickness of about 15 μm, and the solvent in the applied active material is removed. In order to dry, it presses for increasing the density of an active material, and performs a slit and a cutting process. As the material of the current collector, for example, high-purity aluminum foil material as shown in Patent Document 1 was used.

In recent years, however, aluminum alloy foils with high strength have been oriented because of thinning of the aluminum foils used in accordance with the progress of battery high capacity. For example, as disclosed in Non-Patent Document 1, in 1085, 1N30 and the like, which are conventionally used pure aluminum, the tensile strength is 172 to 185 MPa, and the elongation value is 1.4 to 1.7%. By adding, aluminum alloy foil having a tensile strength of 270 to 279 MPa and an elongation value of 1.3 to 1.8% is commercially available, and further high strength or high elongation has been oriented.

For example, Patent Document 2 proposes the following. That is, when a hard active material is used, when it is stored in a battery case, it becomes the tendency for the spirally wound (bent) electrode material to break in the small radius part. Therefore, in the Al-Mn alloy foil, the Cu content is increased, and the sheet is subjected to intermediate annealing under predetermined conditions using a continuous annealing furnace at a predetermined plate thickness during cold rolling, thereby achieving a strength of 280 to 380 MPa. A proposal to improve the curvature is made.

For example, Patent Literature 3 also proposes to add Mg, Co, Zr, W, and the like to an aluminum alloy foil to achieve strength of 240 to 400 MPa to obtain elongation and corrosion resistance.

On the other hand, Non-Patent Document 2 discloses that as a general characteristic, the conductivity is 61.5% IACS in 1085 which is pure aluminum, and is higher (lower electrical resistance value) than 48.5% of the Mn-added 3003 alloy. Due to this high electrical conductivity, pure aluminum foil, which is preferred for use in electric parts, is still widely used. On the other hand, the electrical conductivity varies depending on the alloying element and the roughness, and as disclosed in Non Patent Literature 3, in a 1070 material having a high purity and the like at a thickness of 6 mm or more, the soft (O) material It is known that 62%, 61% for the hard (H18) material, and 50% for the soft material and 40% for the hard material in the case of the 3003 alloy. In other words, in Mn-based alloys, the electrical conductivity is greatly reduced by the processing.

Japanese Patent Laid-Open No. 11-162470 (paragraph 0023) Japanese Patent Application Laid-Open No. 2008-150651 (paragraphs 0003, 0005 to 0007) Japanese Patent Publication No. 2009-64560 (paragraphs 0016 to 0029)

2008 Latest Battery Technology Competition, Electronic Journal, May 1, 2008, Part 8 Chapter 1 Section 7, P243 Furukawa-Sky Review, No.5, 2008 P5 Table 1, P9 Fig. 8 Aluminum Handbook, Japan Aluminum Association, published January 31, 2007, P32, Table 4.2

However, in the conventional aluminum foil and aluminum alloy foil, there exist the following problems.

In aluminum foil and aluminum alloy foil, it is known that elongation (ductility) decreases with an increase in strength and a decrease in foil thickness. In addition, this is also specified in the nonpatent literature 1.

However, in processes such as crimping and slit in the electrode material production line, there is a problem that if the elongation is small, even if the elongation is low, the foil becomes brittle, the foil breaks in the production line, and an obstacle occurs such that the line is stopped. Indeed, strength has been emphasized. On the other hand, in the alloy thin material in which Mn is added in a large amount for high strength, as stated in Non Patent Literature 2, since the electrical resistance is large, there is a problem that it is not preferable at the time of use as a battery after assembly.

This invention is made | formed in view of the said problem, and makes it a subject to provide the aluminum rigid foil for battery collectors which have some intensity | strength, excellent elongation, and low electrical resistance.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the present inventors examined the following matters.

It is well-known that what is necessary is just to add Mg, Mn, Cu, etc. for the high strength of foil, and it is used also for the proposal by the said prior art. However, no means of increasing the ductility of thin hard foils is known. Moreover, in pure aluminum foil and 8021 alloy foil, although electrical conductivity was high, it was insufficient in the point of strength and elongation.

In general, in the production of pure aluminum thin foils such as 1N30, by the solid solution and precipitation control in the manufacturing process of the material and the control of the foil rolling conditions, the material structure before finishing foil rolling is converted into a subgrain structure. It is known that thin foil with few pinholes can be manufactured by this. Since this elongation state is also relatively high, it was thought that high ductility is obtained, even if it is comparatively high in strength, if a microcrystal can be controlled finely.

Usually, although the material structure of foil is observed with a transmission electron microscope etc. in many cases, only local information is acquired and observation in the whole cross section area | region of foil of about 15 micrometers thick was made. Therefore, as a result of earnestly studying the influence of various factors on the elongation of the hard foil, it is inferred that the size of the crystal grains (a-crystal grains) in the thickness direction and the rolling direction correlates with the elongation, and observation of the sub-crystal grains in the cross section of the foil The present invention has been achieved by newly establishing conditions. That is, even if it was a hard foil of any state, it turned out that the amorphous grain diameter (thickness direction and rolling direction) in a cross section is nonuniform. By this life point, the inventors of the present invention are conventionally uneven deformation because the size of the amorphous grains in the thickness direction and the rolling direction is large, and the elongation was low, and the size of the amorphous grains in the thickness direction and the rolling direction is small. When controlled so as to make it possible to obtain a uniform deformation by tensile deformation or the like and to obtain a high elongation, the present invention has been completed. It is also known that the crystal grains at the time of intermediate annealing are rolled and grown and formed from a thinned layer. In order to form small crystallites in the thickness direction and the rolling direction, the number of crystal grains at the time of intermediate annealing and solid solution We also found that controlling the state is a necessary condition.

In addition, the present inventors measured the electrical conductivity in real foil, and discovered that the actual electrical conductivity is lower than the numerical value described in the nonpatent literature 1, 2 because it is a thin hard foil.

Thus, although alloy foil (Al purity: less than 99.0 mass%) which added the alloying element for the high strength conventionally has been aimed, this invention is high strength and high elongation in the range of pure aluminum for the fall and suppression of an electrical resistance. It is intended.

That is, the aluminum hard foil for battery collectors (henceforth "aluminum foil" suitably) which concerns on this invention contains Fe: 1.4-1.7 mass%, Cu: 0.1-0.5 mass%, Si: 0.4 mass% It is suppressed below and remainder consists of Al and an unavoidable impurity, and the magnitude | size of a crystal grain is 0.8 micrometer or less in thickness direction, and 45 micrometers or less in rolling direction.

Moreover, as said aluminum hard foil for battery collectors manufactured by the polymerization rolling, it is preferable that thickness is 5-20 micrometers, tensile strength is 240 Mpa or more, and elongation is 2.6% or more.

Moreover, as said aluminum hard foil for battery collectors manufactured by single rolling, it is preferable that thickness is 9-20 micrometers, tensile strength is 240 Mpa or more, and elongation is 4.0% or more.

According to such a structure, by adding a predetermined amount of Fe, the crystal grain becomes fine during intermediate annealing and foil rolling, and by adding a predetermined amount of Fe and Cu, the strength of the aluminum foil is improved, and the tensile strength is single rolling and polymerization rolling. All are 240 MPa or more, and it becomes sufficient strength as aluminum. Moreover, when Cu content is made into 0.5 mass% or less, 53% or more of electrical conductivity is obtained, and it becomes what has sufficient characteristics as a battery collector. In addition, by suppressing Si to a predetermined amount or less, the Al-Fe-based intermetallic compound hardly becomes a coarse α-Al-Fe-Si-based intermetallic compound, so that the elongation does not decrease. Moreover, the grain size does not become coarse, and sufficient crystal grain number is obtained in the thickness direction. Moreover, it can be set as aluminum foil suitable for battery collectors by making thickness into 9-20 micrometers (for single rolling) and 5-20 micrometers (for polymerization rolling). In addition, the elongation of aluminum foil is improved by making the size of the thickness direction of acrystalline grain into 0.8 micrometer or less and 45 micrometers or less in a rolling direction, and elongation is 4.0% or more in case of single rolling, and 2.6% or more in case of polymerization rolling. This becomes sufficient elongation as aluminum.

It is preferable that the aluminum hard foil for battery collectors which concerns on this invention contains 1 or more types of Mn: 0.5 mass% or less and Mg: 0.05 mass% or less further.

According to such a structure, intensity | strength can be raised by adding at least any one of Mn and Mg further. And in that case, elongation does not fall by making Mn into the addition amount below a predetermined amount, and elongation and electrical conductivity do not fall by making Mg into the addition amount below a predetermined amount.

It is preferable that the aluminum rigid foil for battery collectors which concerns on this invention is 53% (IACS) or more in electrical conductivity.

According to such a structure, the efficiency of a battery improves at the time of use as a battery.

Even if the aluminum rigid foil for battery collectors according to the present invention has a thickness of 9 to 20 µm (in the case of single rolling) and 5 to 20 µm (in the case of polymerization rolling), the pure aluminum has high strength, and thus the electrical resistance is low. In addition, the capacity of the lithium ion secondary battery can be increased. Moreover, since elongation is also excellent, breakage of foil can be prevented in the manufacturing process of an electrode material, and generation | occurrence | production of the obstacle, such as a production line being stopped, can be prevented.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the aluminum hard foil for battery collectors (henceforth "aluminum foil" suitably) which concerns on this invention is demonstrated.

The aluminum foil which concerns on this invention contains a predetermined amount of Fe and Cu, suppresses Si to a predetermined amount or less, and remainder consists of Al and an unavoidable impurity. And the thickness of this aluminum foil is 9-20 micrometers (in the case of single rolling), 5-20 micrometers (in the case of polymerization rolling), The magnitude | size of the amorphous grain of this thickness direction is 0.8 micrometer or less, and the magnitude | size of a rolling direction is 45 It is micrometer or less. In addition, tensile strength is prescribed | regulated as 240 Mpa or more in both single-rolling and superposition | polymerization rolling, and elongation is 4.0% or more when manufactured by single rolling, and 2.6% or more when manufactured by polymerization rolling. In addition, the aluminum foil may contain a predetermined amount of at least one of Mn and Mg. And the electrical conductivity of aluminum foil will be 53% or more.

Hereinafter, each configuration will be described.

(Fe: 1.4-1.7 mass%)

Fe is an element added for the crystal grain refinement at the time of intermediate annealing, and also for the strength improvement by it, for stabilizing a crystal grain. When manufactured by polymerization rolling, when Fe content is less than 1.4 mass%, a grain size will become coarse, roughness of a mat surface will become rough, and sufficient elongation will be hard to be obtained.

Moreover, when manufactured by single rolling and when manufactured by polymerization rolling, when Fe content exceeds 1.7 mass%, a coarse precipitate will be formed and elongation will fall.

Therefore, Fe content shall be 1.4-1.7 mass%.

(Cu: 0.1-0.5 mass%)

Cu is an element added for the strength improvement by solid solution strengthening. If it is less than 0.1 mass%, the strength becomes insufficient. When it exceeds 0.5 mass%, elongation will fall. Since about half of the added content enters the second phase such as precipitates and dispersed particles, the conductivity is higher than that in the case where the same amount of Mn is added.

Therefore, Cu content is made into 0.1 to 0.5 mass%.

(Si: 0.4 mass% or less)

Si is an element likely to be incorporated as an unavoidable impurity. When Si content exceeds 0.4 mass%, Al-Fe type intermetallic compound will become coarse alpha-Al-Fe-Si type intermetallic compound, and elongation is hard to be obtained. In addition, by decreasing the distribution density of the intermetallic compound, the grain size becomes coarse, and the size of the subcrystal grains cannot be sufficiently reduced.

Therefore, Si content is made into 0.4 mass% or less. Preferably, it is 0.2 mass% or less. In addition, Si may be 0 mass%.

(Mn: 0.5 mass% or less)

Mn is also a preferable element for strength improvement and can be added. However, when it exceeds 0.5 mass%, electrical conductivity will fall.

Therefore, Mn content is made into 0.5 mass% or less when adding.

(Mg: 0.05 mass% or less)

Mg is also a preferable element for strength improvement, and can also be added. However, when it exceeds 0.05 mass%, elongation will fall. In addition, the electrical conductivity is lowered.

Therefore, Mg content is made into 0.05 mass% or less when adding.

(Ti, etc.)

In addition, in order to refine the ingot structure, an Al-Ti-B intermediate alloy may be added. That is, ingot refiner having a ratio of Ti: B = 5: 1 or 5: 0.2 is melted in the form of waffle or rod (melting furnace, inclusion filter, degassing apparatus, molten metal before slab solidification). Molten metal at any stage added to the flow control device), and the content of up to 0.1% by mass in the Ti amount is allowed. On the other hand, when Ti exceeds 0.1 mass%, electrical conductivity will fall.

Moreover, although Cr, Zr, and V may be added for grain refinement, in order to avoid the fall of electrical conductivity, when adding, the content of Cr, Zr, and V is preferably 0.5% by mass or less.

(Remainder: Al and inevitable impurities)

In addition to the above, the component of the aluminum foil is made of Al and unavoidable impurities. On the other hand, containing up to 0.1 mass% of Zn as an unavoidable impurity is permissible. If the amount of Zn exceeds 0.1 mass%, corrosion resistance will worsen. In addition, Ga, Ni, etc. in the normally known range contained in now and intermediate | middle alloy are contained up to 0.05 mass%, respectively.

(Thickness: polymerization rolled foil 5-20 micrometers, single rolled foil 9-20 micrometers)

In order to increase the battery capacity of the lithium ion secondary battery, the thickness of the aluminum foil should be as thin as possible, but it is difficult to produce a high strength foil of less than 9 μm in single rolling, and a high strength of less than 5 μm in polymerization rolling. It is difficult to make gourds. Moreover, when it exceeds 20 micrometers, many electrode materials cannot be put in the case of the determined volume, and battery capacity falls. Therefore, the thickness of aluminum foil shall be 5-20 micrometers in 9-20 micrometers and polymerization rolling foil in single rolled foil.

(Glass grain size: 0.8 micrometers or less in thickness direction, 45 micrometers or less in rolling direction)

In order to increase the elongation in the aluminum foil having a thickness of 9 to 20 µm (for single rolling) and 5 to 20 µm (for polymerization rolling), the grain size is 0.8 µm or less in the thickness direction and 45 µm in the rolling direction. It is necessary to make the following. In the size larger than that, the elongation of the aluminum foil is not sufficiently obtained. In addition, the finer the grain size, the better. The lower limit is not particularly limited.

Next, the establishment of the measuring method of the size of the amorphous grain in a thickness direction and a rolling direction is demonstrated.

First, the aluminum foil is cut into about 5 x 10 mm, and the cut foil is attached to the thin board substrate using a conductive tape so that the foil is slightly protruded. Next, a portion of the foil is cut with a Focused Ion Beam (FIB) device so that the parallel cross section can be observed. On the other hand, with the resin filling method which is used abundantly, a resin part charges up at the time of SEM (scanning electron microscope) observation, and measurement is difficult. The observation magnification is x2000 times for this cross section, and EBSD (Electron Back Scatter Diffraction) analysis is performed to obtain an orientation mapping image. The measurement was performed in 10 fields with respect to one sample. On the other hand, normally, since it observes from a surface, analysis software automatically displays the orientation mapping image of the ND surface seen from the surface. In this analysis, it is a parallel cross section (RD-TD surface) observation, and rotates so that the orientation mapping image of the ND surface seen from the RD-ND surface may be obtained. And the magnitude | size of a sub-crystal grain is computed by the line segment method by this obtained orientation mapping image. Specifically, it is as follows. In the crystal grains, the inclination angle between the crystal grains is 0 to 15 °, and the boundary below the inclination angle of 15 ° and the boundary of the inclination angle of 15 ° or more can be displayed by color on the azimuth mapping with a line on the orientation mapping. Based on this matter, the inclination angle and color between the crystal grains are visually determined from the orientation mapping image (orientation mapping diagram), and the size of the subcrystal grains is measured.

Tensile strength: 240 MPa or more

If the tensile strength is 240 MPa or more, sufficient strength can be ensured as the foil for battery collectors of various types.

Therefore, tensile strength shall be 240 Mpa or more.

(Elongation: 2.6% or more (in the case of polymerization rolling), 4.0% or more (in the case of single rolling))

As the strength is slightly inferior to that of the 3000 series alloy foil, more excellent elongation is required. As aluminum foil manufactured by single rolling, elongation 4.0% or more is sufficient elongation as foil for battery collectors. In addition, the elongation of the aluminum foil manufactured by polymerization rolling should just be 2.6% or more.

Therefore, elongation shall be 2.6% or more (in the case of polymerization rolling), and 4.0% or more (in the case of single rolling). On the other hand, the higher the elongation, the better.

The measurement of tensile strength and elongation cuts out 15 mm (width) x about 200 mm (length) single type test piece so that the tensile direction may become parallel to a rolling direction from the width direction center part of an aluminum foil, and scores 100 mm between chuck distances. Carry out the distance between them. Elongation is calculated from the displacement of the cross head. The number of tests is five times for one kind of material. Tensile strength and elongation are to be averaged three times except the maximum and minimum of five times. Tensilon universal testing machine type: RTC-1225A made from Orient Tech Co., Ltd. can be used for a test.

(Conductivity: 53% or more)

In order to use it as an electrical component, it is necessary to have low electrical resistance. If the electrical resistance is low, that is, the conductivity is 53% or more, the efficiency is improved at the time of use as a battery. Therefore, electrical conductivity is made into 53% or more. On the other hand, the higher the electrical conductivity, the better.

On the other hand, by setting it as the structure of this invention, the aluminum foil of 9-20 micrometers (for single rolling) and 5-20 micrometers (for polymerization rolling) thickness WHEREIN: 53% or more of electrical conductivity is obtained, and it is sufficient characteristic as a battery collector It is to have. The measurement is performed in the vicinity of the center portion in the width direction of the aluminum foil, and the number of measurements is performed four times for one kind of material.

Next, the measurement (calculation) method of electrical conductivity is demonstrated. This measurement can be performed by measuring an electrical resistance by the DC 4-terminal method using the electrical resistance measuring apparatus TER-2000RH made from Al-Peelong Co., Ltd. in accordance with JIS C2525.

Specifically, first, a foil of a predetermined thickness is cut into a predetermined size, Ni wire is spot welded at both ends, and electrical resistance is measured by the four-terminal method. The resistance R of the test piece is obtained by R = V / I from the potential difference V between the current I flowing through the sample and the voltage terminal. The current I is obtained from the voltage drop of the standard resistor (0.1 Ω) connected in series with the specimen. The voltage drop of the test piece and the standard resistor and the electromotive force of the R thermocouple are obtained by using a digital multimeter with a detection sensitivity of ± 0.1 μV. And electrical conductivity is calculated | required by the following formula.

Volume resistivity ρ = R (A / L)

Conductivity γ (% IACS) = {1.7241 [μΩ · cm] / Volume Resistance ρ [μΩ · cm]} × 100

    A: Sample cross section

    L: measuring part length

    1.7241 [μΩ · cm]: Volume resistivity of standard interlock

[Production method of aluminum foil]

Next, the manufacturing method of an aluminum foil is demonstrated. The manufacturing method of an aluminum foil is to perform a homogenization heat treatment and hot rolling of an aluminum ingot by a predetermined method, and to cold-roll on predetermined conditions, an intermediate annealing as needed, and to perform cold rolling and foil rolling after that. . On the other hand, foil rolling is generally performed by any method of single rolling or polymerization rolling. Here, the polymerization rolling means that two sheets of aluminum foil are piled up in a final pass and supplied to a roll and rolled. Single rolling means that one aluminum foil is supplied to a roll and rolled up to a final pass.

In the aluminum foil, in order to reduce the size of the amorphous grains, it is preferable not to perform the intermediate annealing or to make the grain size at the time of the intermediate annealing fine by rapid heating and rapid cooling of the intermediate annealing by continuous annealing (CAL). Therefore, it is preferable that the cold work rate (cold rolling rate) from hot rolling to intermediate annealing is high, and it is preferable to set it as 30% or more of cold rolling rate. Moreover, also in order to improve strength, it is preferable to set it as cold rolling rate of 30% or more. If the cold rolling rate to intermediate annealing exceeds 85%, the effect is saturated and not economical, so 85% or less is preferable. However, when the intermediate annealing is carried out by batch annealing, the grain size of the recrystallization at the time of the intermediate annealing becomes coarse, and the elongation is lowered than when the intermediate annealing is not performed.

After the intermediate annealing, the aluminum foil is formed at a high cold rolling rate to promote the crystallization, and in particular, the strength needs to be improved. Therefore, the cold rolling rate after the intermediate annealing, that is, the final aluminum foil after the intermediate annealing (final product) It is preferable to make the total cold rolling rate until) into 98.5% or more, and therefore, it is preferable to make the plate | board thickness at the time of intermediate annealing to 1 mm or more. On the other hand, in order to obtain high strength in aluminum foil, the plate thickness at the time of intermediate annealing is preferably 1 mm or more. However, when the intermediate annealing is performed at a thickness exceeding 2 mm, since the strength is too high and foil rolling is likely to be difficult, 2 mm or less is preferable. On the other hand, in order to make foil rolling easy, even if the absolute value of intensity | strength is a high value, it is preferable that there is little work hardening in foil thickness of about 100 micrometer thickness or less. In addition, in order to promote the crystallization by foil rolling, temperature rise is required to some extent and it is performed so that it may become about 40-100 degreeC after coil winding. In the absence of a temperature rise during foil rolling, it is difficult to refine the grains due to the crystallization.

Homogenization heat processing performs a cracking temperature on 350 degreeC or more and 560 degrees C or less conditions. If the cracking temperature is less than 350 ° C, the homogenization is insufficient and the elongation of the aluminum foil is lowered. When the cracking temperature exceeds 560 ° C, the dispersed particles are coarse and coarsely distributed, the grain boundary pin stopping force is lowered, fine grains are not obtained, and the elongation of the aluminum foil is lowered. The low temperature side is preferable in the range of the crack temperature of 350 degreeC or more and 560 degrees C or less, in order to increase the grain boundary pin stopping force of a dispersed particle, and to refine a grain of foil.

Since the intermediate annealing makes the recrystallized grain size fine and sets the size of the thin crystal grains to 0.8 µm or less in the thickness direction and 45 µm or less in the rolling direction, it is annealed in the continuous annealing furnace. And annealing temperature (reaching temperature) is performed on the conditions of 380 degreeC or more and 550 degrees C or less and holding time on 1 minute or less.

If the annealing temperature is less than 380 ° C, recrystallization does not proceed sufficiently, the size of the amorphous grains increases, and the degree of solid solution becomes insufficient. On the other hand, when it exceeds 550 degreeC, the effect of recrystallization and solid solution will be saturated, and surface appearance will become easy to deteriorate. In addition, although the temperature raising / lowering speed should just be a range of the conventional method in continuous annealing, even if it is a range of the conventional method in batch annealing, precipitation advances during heating, and coalescing and coarsening of a crystal grain at the time of foil rolling is carried out. Will proceed. Moreover, the degree of work hardening is also inadequate and strength falls. On the other hand, in the case of continuous annealing, the temperature increase rate is 1-100 degreeC / sec, and the temperature-fall rate 1-500 degreeC / sec is a range of a conventional method. In the case of batch annealing, the temperature increase rate is 20-60 degreeC / hour, and the temperature-fall rate is arbitrarily applied to furnace cooling, room cooling, forced air cooling, etc., and is based on these conditions.

In addition, although it is preferable that the holding time is long for employment, the holding time exceeding 1 minute is economically inferior because the holding speed exceeding 1 minute is significantly slowed because it is a continuous annealing furnace.

In this way, the size of the sub-crystal grains in the thickness direction and the rolling direction can be controlled by the component range, the number of crystal grains at the time of intermediate annealing, and the solid solution state.

Example

As mentioned above, although the form for implementing this invention was described, the Example which confirmed the effect of this invention is demonstrated concretely in contrast with the comparative example which does not satisfy the requirements of this invention. In addition, this invention is not limited to this Example.

[Production of test materials]

(Invention Example No. 1 to 9, Comparative Example No. 10 to 20)

The aluminum of the composition shown in Table 1 was melt | dissolved, cast, it was made into ingot, and after this ingot was face-treated, the homogenization heat processing for 2 to 4 hours was performed in the range of 360-650 degreeC. After performing hot rolling and further cold rolling to this homogenized ingot, the intermediate annealing was performed, and it cold-rolled to thickness of 15 micrometers after that, and it was set as aluminum foil. The conditions of intermediate annealing and cold rolling are as showing in Table 1.

On the other hand, in the case of continuous annealing (CAL), the temperature increase rate is 10 ° C / second, the temperature-fall rate is 20 ° C / second, in the case of batch annealing (BATCH), the temperature increase rate is 40 ° C / hour, the temperature-fall rate is 80 ° C / hour It was set as (cooling). In addition, the total cold rolling rate is an approximate value.

Table 1 shows the component composition, properties and manufacturing conditions in the case of producing aluminum foil by single rolling or polymerization rolling. In addition, in a table | surface, the thing which does not satisfy the range of this invention and the manufacturing conditions are underlined in a numerical value etc., and are shown. In addition, in Table 1, the plate | board thickness after hot rolling is described as hot rolling finish thickness, and the plate | board thickness before intermediate annealing is described as intermediate | middle annealing thickness.

[Size of subcrystal grains]

Next, the magnitude | size of the amorphous grain in the thickness direction and the rolling direction of aluminum foil was measured by the following method.

First, the aluminum foil was cut to about 5 x 10 mm, and the cut foil was attached to a thin board substrate using a conductive tape so that the foil was slightly protruded. Next, the part of this foil was cut | disconnected with the FIB (Focused Ion Beam) apparatus, and the parallel cross section was observed. And about this cross section, the observation magnification was made into x2000 times with the scanning electron microscope, and EBSD (Electron Back Scatter Diffraction) analysis was performed, and the orientation mapping image was obtained over the whole thickness of foil. It measured by 10 o'clock per sample. On the other hand, normally, since it observes from a surface, analysis software automatically displays the orientation mapping image of the ND surface seen from the surface. In this analysis, it was a parallel cross section (RD-TD surface) observation, and it rotated so that the orientation mapping image of the ND surface seen from the RD-ND surface might be obtained. And based on this orientation mapping image, the grain size was computed by the line segment method.

The results are shown in Table 1.

Here, the area | region enclosed in 15 degrees or less of the inclination angle between crystal grains is a subcrystalline grain, and the subcrystal grains of the same crystal direction become the same color. On the other hand, the relationship between the color and the crystal direction is indicated by the color code. Incidentally, the inclination angle between the sub-crystal grains is 0 to 15 degrees, but the boundary of the inclination angle 0 to 15 degrees can be indicated by a line on the orientation mapping. In addition, the above-mentioned matters were measured, and the size of the subcrystal grains was measured by visual determination of the orientation mapping degree. On the other hand, although the location of a crystal grain is a micro area | region, although a grain size differs according to a place, in the measurement of size, the largest crystal grain size was measured here.

[Conductivity]

Next, the electrical conductivity of the aluminum foil was measured by the following method. This measurement was performed by measuring an electrical resistance by the DC 4-terminal method using the electrical resistance measuring apparatus TER-2000RH made from Al-Peeling Co., Ltd. in accordance with JIS C2525.

Specifically, first, foil of a predetermined thickness was cut into 3 mm (width) x 80 mm (length), Ni-wire was spot-welded at both ends, and electrical resistance was measured by the 4-terminal method. The resistance R of the test piece was calculated from R = V / I from the potential difference V between the current I flowing through the sample and the voltage terminal. The current I was obtained from the voltage drop of the standard resistor (0.1?) Connected in series with the test piece. The voltage drop of the test piece and the standard resistor and the electromotive force of the R thermocouple were obtained using a digital multimeter with a detection sensitivity of ± 0.1 μV. Electrical conductivity was calculated | required by the following formula.

Volume resistivity ρ = R (A / L)

Conductivity γ (% IACS) = {1.7241 [μΩ · cm] / Volume Resistance ρ [μΩ · cm]} × 100

    A: Sample cross section

    L: measuring part length

    1.7241 [μΩ · cm]: Volume resistivity of standard interlock

〔evaluation〕

The following evaluation was performed with the obtained aluminum foil.

(Strength and elongation)

Tensile strength and elongation were measured using Type B test specimens in accordance with the Light Metal Association standard LIS AT5. That is, the 15 mm (width) x about 200 mm (length) single-piece test piece was cut out from aluminum foil so that the tension direction might become parallel to a rolling direction, and it implemented by making the distance between chuck | zipper distance 100mm into rating distance. Tensilon universal testing machine type: RTC-1225A made from Orient Tech Co., Ltd. was used for the test. In this test, tensile strength and elongation were measured. About the aluminum foil manufactured by single rolling, the acceptance criterion of tensile strength was 240 Mpa or more, and the elongation acceptance criteria was 3.5% or more. On the other hand, regarding the aluminum foil manufactured by polymerization rolling, the acceptance criteria of tensile strength were 240 MPa or more, and the acceptance criteria of elongation was 2.0% or more.

The results are shown in Table 1. In addition, in a table | surface, it is underlined in numerical value that tensile strength, elongation, and electrical conductivity do not satisfy an acceptance criterion.

(Evaluation by aluminum foil)

As shown in Table 1, Nos. 1 to 9 which are inventive examples satisfied the range of the present invention, and thus were excellent in strength and elongation, and their electrical conductivity was 53.0% or more.

On the other hand, Nos. 10 to 20, which are comparative examples, did not satisfy the scope of the present invention, resulting in the following results.

Since the Fe content exceeded the upper limit in No. 10, the α-Al-Fe-Si-based intermetallic compound coarsened and became a starting point of breakage, and the elongation of the polymer-rolled foil was inferior. Since the Fe content was less than the lower limit in No. 11, the mat surface became rough, and the elongation of the polymerization rolled foil was inferior. In No. 12 and 13, since Cu content exceeded the upper limit, elongation fell. In No. 14, since the Cu content was less than the lower limit, the strength decreased. In No. 15, the conductivity was lowered because the Mn content exceeded the upper limit. No. 16 was inferior in elongation because the Mg content exceeded the upper limit.

In No. 17, since the Si content exceeded the upper limit, the α-Al-Fe-Si-based intermetallic compound coarsened, resulting in breakage, and the elongation was inferior.

In No. 18, since the intermediate annealing was a batch type, fine grains were not obtained at the time of intermediate annealing, but the grains were grown and coalesced at the time of rolling, and a fine grain structure was not obtained. Therefore, the grain size exceeded the upper limit and the elongation was inferior.

In No. 19, since the Fe content exceeded the upper limit, the α-Al-Fe-Si-based intermetallic compound coarsened, resulting in breakage, and the elongation of the rolled foil was inferior. Since Fe content was less than a lower limit in No. 20, the grain size became coarse, and the grain size became more than an upper limit. Therefore, the strength and elongation of the rolled foil were inferior.

As mentioned above, although the embodiment and the Example were demonstrated about the aluminum rigid foil for battery collectors concerning this invention in detail, the meaning of this invention is not limited to the above-mentioned content. It is needless to say that the contents of the present invention can be widely modified, changed, etc. based on the above description.

Claims (6)

Fe: 1.4-1.7 mass%, Cu: 0.1-0.5 mass%, Si: 0.4 mass% or less, remainder consists of Al and an unavoidable impurity, and the size of a crystal grain is 0.8 micrometer in a thickness direction Hereinafter, it is 45 micrometers or less in a rolling direction, The aluminum hard foil for battery collectors characterized by the above-mentioned. The method of claim 1,
As produced by polymerization rolling,
The aluminum rigid foil for battery collectors whose thickness is 5-20 micrometers, tensile strength is 240 Mpa or more, and elongation is 2.6% or more. The method of claim 1,
As manufactured by single rolling,
The aluminum rigid foil for battery collectors whose thickness is 9-20 micrometers, tensile strength is 240 Mpa or more, and elongation is 4.0% or more. 4. The method according to any one of claims 1 to 3,
Furthermore, aluminum hard foil for battery collectors containing 1 or more types of Mn: 0.5 mass% or less and Mg: 0.05 mass% or less. 4. The method according to any one of claims 1 to 3,
The aluminum rigid foil for battery collectors whose electrical conductivity is 53% or more. 5. The method of claim 4,
The aluminum rigid foil for battery collectors whose electrical conductivity is 53% or more.