JP5405410B2 - Aluminum alloy hard foil for battery current collector - Google Patents

Description

  The present invention relates to an aluminum alloy hard foil for a battery current collector 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 mobile phones and notebook computers. The electrode material of such a lithium ion secondary battery is formed of a positive electrode material, a separator, and a negative electrode material. Then, the positive electrode material is manufactured by applying an active material such as LiCoO _{2 having a} thickness of about 100 μm to both sides of an aluminum foil for collector (or aluminum alloy foil) having a thickness of about 15 μm. Drying is performed to remove the solvent, and pressure bonding for increasing the density of the active material is performed, and the process is performed through a slitting and cutting process. In addition, the drying process for removing a solvent is performed on the conditions hold | maintained at 100-150 degreeC for about 30 minutes.

  In recent years, high-strength aluminum alloy foils have been aimed at in order to reduce the thickness of the aluminum alloy foil to be used as the capacity of the battery increases. Therefore, for example, as disclosed in Non-Patent Document 1, 3003 alloys and developed products having higher strength than conventional 1085 and 1N30 have been used, and strengths of 230 to 345 MPa using these have been used. Aluminum alloy foils are commercially available.

  Further, for example, Patent Document 1 proposes the following proposal. That is, in the Al-Mn alloy foil, when the aluminum foil is softened by the active material drying process and the strength is reduced, the softened foil is easily stretched in the crimping process after drying, and the coating portion of the electrode mixture is not stretched. Waves of aluminum foil occur at the boundary of the coating part. Therefore, proposals have been made to increase the strength at the time of 0.1% elongation to about 168 to 240 MPa.

Further, for example, Patent Document 2 proposes the following proposal. That is, when a hard active material is used, when it is housed in a battery case, the electrode material wound (bent) in a spiral shape tends to be easily broken at a portion having a small radius. Therefore, in the Al-Mn alloy foil, by increasing the Cu content and performing intermediate annealing under predetermined conditions using a continuous annealing furnace at a predetermined plate thickness during cold rolling, as a strength of 280 to 380 MPa, Proposals for improving the bending resistance have been made.
For example, Patent Document 3 proposes that Mg, Co, Zr, W, or the like is added to obtain a strength of 240 to 400 MPa to obtain elongation and corrosion resistance.

JP-A-11-67220 (paragraphs 0003 and 0007, Tables 1 and 2) Japanese Patent Laying-Open No. 2008-150651 (paragraphs 0003 and 0005 to 0007) JP 2009-64560 A (paragraphs 0016 to 0029)

“2008 Newest Battery Technology Encyclopedia”, Electronic Journal Co., Ltd., published on May 1, 2008, Volume 8, Chapter 1, Section 7, P243

However, the conventional aluminum alloy foil has the following problems.
In an aluminum alloy foil, it is known that elongation (ductility) decreases as the strength increases and the foil thickness decreases. This is also specified in Non-Patent Document 1, and in the example in Patent Document 3, the elongation is only about 3.1% at a tensile strength of 290 MPa, for example. Moreover, when foil rolling is performed by superposition rolling, elongation is reduced as compared with the case of performing single rolling.
However, in processes such as crimping and slitting in the electrode material production line, if the elongation is low even if it is high strength, the foil becomes brittle, causing troubles that the foil breaks in the production line and the line stops. There is a problem of doing.

  This invention is made | formed in view of the said problem, and makes it a subject to provide the aluminum alloy hard foil for battery collectors which is high intensity | strength while having high intensity | strength.

In order to solve the above problems, the present inventors have examined the following matters.
In order to increase the strength of the foil, it is known that Mg, Mn, Cu or the like may be added, and it is also used for the proposal in the prior art. However, no means for increasing the ductility (rollability) of the thin hard foil has been known. On the other hand, when manufacturing pure aluminum thin-walled foils, the material structure before finish foil rolling is made sub-grain structure by controlling solid solution / precipitation in the material manufacturing process and foil rolling conditions, thereby reducing pinholes. It was known that thin foils could be produced. Since this structure is relatively high in elongation, it was considered that even Al-Mn alloy foils with high strength can obtain high ductility by forming a subgrain structure and making the subgrain finer. .

  Normally, when the material structure of the foil is observed from the surface side with a transmission electron microscope or the like, it is known that the subgrain has a diameter of about 2 μm, but observation has been made on the cross section of the foil having a thickness of about 15 μm. There wasn't. Therefore, as a result of diligent research on the influence of various factors on the elongation of hard foil, it was speculated that the crystal grains (subgrains) in the thickness direction correlated with the elongation, and newly established subgrain observation conditions in the foil cross section. As a result, the present invention was achieved. That is, in any state of the hard foil, the subgrain diameter (thickness) in the cross section is about 1.5 to 3 μm (15 μm) although the subgrain diameter observed from the surface does not change to about 2 μm. It was determined that the number of subgrains in the thickness direction was about 5 to 10 with a thick foil. From this investigation point, the present inventors conventionally have non-uniform deformation because the number of subgrains in the thickness direction is small, and that the elongation is low, and when the number of subgrains in the thickness direction is controlled to be large. The inventors have investigated that uniform deformation is possible by tensile deformation or the like and that high elongation can be obtained, and the present invention has been completed. In order to form sub-grains in the thickness direction, the crystal grain size during intermediate annealing is rolled and grown from a thinned layer, and in order to form a large number of sub-grains in the thickness direction, It was also found that it is necessary to control the number of grains and the solid solution state.

  That is, the aluminum alloy hard foil for battery current collector according to the present invention (hereinafter, appropriately referred to as “aluminum alloy foil”) is an aluminum alloy hard foil for battery current collector manufactured by polymerization rolling, and has an Mn of 0.00. 8 to 1.5% by mass, Cu: 0.05 to 0.20% by mass, Fe: 0.3 to 0.7% by mass, the balance being made of Al and unavoidable impurities, The aluminum alloy hard foil has a thickness of 9 to 15 μm, 30 or more subgrains in the thickness direction, a tensile strength of 280 to 350 MPa, and an elongation of 1.0% or more.

  According to such a configuration, by adding a predetermined amount of Mn, Cu, and Fe, the strength of the aluminum alloy foil is improved, the tensile strength becomes 280 to 350 MPa, sufficient strength, and a predetermined amount of Fe. By adding, crystal grains are refined during intermediate annealing. Moreover, it can be set as the aluminum alloy foil suitable for battery electrical power collectors by setting thickness to 9-15 micrometers. Further, by setting the number of subgrains in the thickness direction to 30 or more, the elongation of the aluminum alloy foil is improved and the elongation becomes 1.0% or more, and the battery current collector has sufficient elongation.

The aluminum alloy hard foil for a battery current collector according to the present invention preferably further contains one or more of Mg: 0.2% by mass or less and Si: 0.6% by mass or less.
According to such a configuration, the strength is improved by adding a predetermined amount of Mg, and the foil rollability is improved by adding a predetermined amount of Si.

The aluminum alloy hard foil for a battery current collector according to the present invention may further contain one or more of Cr: 0.2% by mass or less and Zn: 0.3% by mass or less.
In the aluminum alloy foil of the present invention, even when Cr: 0.2% by mass or less and Zn: 0.3% by mass or less are contained, the various properties of the present application are not adversely affected.

  The aluminum alloy hard foil for a battery current collector according to the present invention has a sufficient strength even when the thickness is 9-15 μm when it is polymerized and rolled. Can be planned. Furthermore, since the elongation is excellent, the rollability (foil rollability) is improved, the foil can be prevented from breaking in the electrode material production process, and troubles such as production line stoppage can be prevented. be able to.

  In addition, the component composition of the present invention is within the component range of JIS3003, but as a difference, even if the component composition is within the same range, by defining subgrains, (1) it is a high strength H material. However, it is possible to use the components of JIS3003 that can achieve high elongation, so it is possible to use materials for other purposes and slabs (ingots) together, reducing productivity and in-process (cash flow) ) Also has a remarkable effect of being excellent.

Hereinafter, the form for implement | achieving the aluminum alloy hard foil (henceforth an aluminum alloy foil suitably) for battery collectors which concerns on this invention is demonstrated.

The aluminum alloy foil according to the present invention is an aluminum alloy hard foil for a battery current collector manufactured by polymerization rolling, and contains a predetermined amount of Mn, Cu, Fe, and the balance is made of Al and inevitable impurities. is there. And the thickness of this aluminum alloy foil is 9-15 micrometers, and 30 or more subgrains exist in this thickness direction. Furthermore, the tensile strength is 280 to 350 MPa, and the elongation is specified to be 1.0% or more.
Each configuration will be described below.

(Mn: 0.8 to 1.5% by mass)
Mn is an element added to increase the strength of the aluminum alloy foil. If the Mn content is less than 0.8% by mass, sufficient strength cannot be obtained. On the other hand, when it exceeds 1.5 mass%, a coarse intermetallic compound will arise and foil rolling property will fall. Therefore, the Mn content is 0.8 to 1.5% by mass.

(Cu: 0.05-0.20 mass%)
Cu is an element added for improving the strength by solid solution strengthening. When the Cu content is less than 0.05% by mass, the suppression of strength reduction during drying of the active material is insufficient. On the other hand, if it exceeds 0.20% by mass, the strength becomes too high and the foil rollability is lowered. Therefore, the Cu content is 0.05 to 0.20 mass%.

(Fe: 0.3-0.7 mass%)
Fe is an element to be added for crystal grain refinement during intermediate annealing and for strength improvement by solid solution strengthening. When the Fe content is less than 0.3% by mass, the crystal grain size becomes coarse, a sufficient number of subgrains cannot be obtained in the thickness direction, and sufficient strength is difficult to obtain. On the other hand, when it exceeds 0.7 mass%, a coarse intermetallic compound will arise and foil rolling property will fall. Therefore, Fe content shall be 0.3-0.7 mass%.

  The aluminum alloy foil according to the present invention may further contain one or more of Mg: 0.2% by mass or less and Si: 0.6% by mass or less. Furthermore, even if one or more of Cr: 0.2% by mass or less and Zn: 0.3% by mass or less are contained, there is no problem.

(Mg: 0.2% by mass or less)
Mg is an element added to improve the strength by solid solution strengthening. However, when the Mg content exceeds 0.2% by mass, the strength becomes too high and the foil rollability is lowered. Therefore, Mg content shall be 0.2 mass% or less.

(Si: 0.6% by mass or less)
Si is an element that contributes to the improvement of foil rollability. Si may be added in a predetermined amount or may be mixed as an impurity. However, if the Si content exceeds 0.6% by mass, an Al—Mn—Si-based intermetallic compound is formed, the crystal grain size becomes coarse, and a sufficient number of subgrains cannot be obtained in the thickness direction. Therefore, the Si content is 0.6% by mass or less. In addition, Preferably, in order to improve foil rolling property more, it is good to add 0.2-0.3 mass%.

(Cr: 0.2% by mass or less)
Although Cr may be mixed as an impurity, inclusion up to 0.2% by mass or less is allowed, and addition within this range does not adversely affect the properties of the present application. Therefore, Cr content shall be 0.2 mass% or less (it suppresses to 0.2 mass% or less).

(Zn: 0.3 mass% or less)
Although Zn may be mixed as an impurity, it is allowed to contain up to 0.3% by mass or less, and within this range, even if it is added, it does not adversely affect the properties of the present application. Therefore, Zn content shall be 0.3 mass% or less (it suppresses to 0.3 mass% or less).

  In addition, Ti and B may be added to refine the ingot structure. That is, the ingot refining agent in the ratio of Ti: B = 5: 1 or 5: 0.2 is melted in the form of a waffle or a rod (melting furnace, inclusion filter, degassing device, before slab solidification, The melt may be added to the molten metal flow control device at any stage), and the Ti content is allowed to be 0.05% by mass.

(Balance: Al and inevitable impurities)
In addition to the above, the aluminum alloy foil is composed of Al and inevitable impurities. As unavoidable impurities, for example, Ga, V, Ni, etc. within a generally known range contained in a metal or an intermediate alloy are allowed to contain up to 0.05% by mass.

(Thickness: 9-15 μm)
In order to increase the battery capacity of the lithium ion secondary battery, the thickness of the aluminum alloy foil should be as thin as possible, but it is difficult to produce a high strength foil of less than 9 μm. On the other hand, when the thickness exceeds 15 μm, a large amount of electrode material cannot be put in a case having a predetermined volume, and the battery capacity is reduced. Therefore, the thickness of aluminum alloy foil shall be 9-15 micrometers. In addition, the surface where the aluminum alloy foils overlap each other during superposition rolling becomes a large surface with no gloss called the matte surface, so the variation in foil thickness depending on the location is larger than that of a single rolled material with gloss on both sides. Become. Therefore, even when the thickness is somewhat uneven, the average value of the foil thickness may be 9 to 15 μm.

(Number of subgrains in the thickness direction: 30 or more)
In order to increase elongation in an aluminum alloy foil having a thickness of 9 to 15 μm, the number of subgrains in the thickness direction should be 30 or more (a subgrain diameter (thickness) of 15 μm thick foil is 0.5 μm or less). is necessary. If the number of subgrains in the thickness direction is less than 30, the aluminum alloy foil cannot be sufficiently stretched. Further, the number of subgrains may be any number as long as the number is large, and the upper limit is not particularly limited. Furthermore, as described above, since the subgrains in the thickness direction are grown and formed from a thinned layer whose crystal grain size during intermediate annealing is rolled, this layer needs to have 30 or more layers. This means that the number of recrystallized grains during intermediate annealing is 30 or more in the thickness direction. In addition, as above-mentioned, when foil thickness is non-uniform | heterogenous by superposition | polymerization rolling, the number of subgrains is 30 in the location of the average value of foil thickness (when there is no location of average value, the location of the value nearest to the average value) It may be more than one.

Next, establishment of a method for measuring the number of subgrains in the thickness direction will be described.
First, the aluminum alloy foil is cut to about 5 × 10 mm, and the cut foil is pasted on a thin plate substrate using a conductive tape so that the foil is slightly protruding. Next, this foil portion is cut with a FIB (Focused Ion Beam) apparatus so that a parallel section can be observed. In the resin filling method that is frequently used, the resin part is charged up during SEM (scanning electron microscope) observation, and measurement is difficult. Then, with respect to this cross section, an observation magnification is set to × 2000 with an SEM, and EBSD (Electron Back Scatter Diffraction) analysis is performed to obtain an orientation mapping image. Since the observation is usually performed from the surface, the analysis software automatically displays an orientation mapping image of the ND plane viewed from the surface. In this analysis, the observation is a parallel cross section (RD-TD plane), and the rotation operation is performed so that an orientation mapping image of the ND plane viewed from the RD-ND plane is obtained. Then, the number of subgrains is calculated by the line segment method from the obtained orientation mapping image. Specifically, it is as follows. The subgrains have an inclination angle between crystal grains of 0 to 15 °, and the same subgrain has the same color. Then, 0 ° is the darkest color, and 15 ° is the lightest color. Based on this matter, the color code indicating the relationship between color and crystal orientation is used to determine the tilt angle and color between crystal grains from the orientation mapping image (orientation mapping diagram) and count the subgrains. To do.

(Tensile strength: 280-350 MPa)
When the tensile strength is less than 280 MPa, the strength as the aluminum alloy foil is insufficient. On the other hand, when it exceeds 350 MPa, foil rollability will fall. Accordingly, the tensile strength is 280 to 350 MPa.

(Elongation: 1.0% or more)
When the elongation is less than 1.0%, the elongation as the battery current collector foil is insufficient. Therefore, the elongation is 1.0% or more. The higher the elongation, the better.

  Measurement of tensile strength and elongation can be carried out using a B-type test piece according to the Light Metal Association Standard LIS AT5. That is, a strip-shaped test piece of 15 mm width × about 200 mm length is cut out from the aluminum alloy foil so that the tensile direction is parallel to the rolling direction, and the distance between the chucks is 100 mm. For the test, Tentecron Universal Testing Machine Model: RTC-1225A manufactured by Orientec Co., Ltd. can be used.

[Method for producing aluminum alloy foil]
Next, the manufacturing method of aluminum alloy foil is demonstrated. The production method of aluminum alloy foil is to perform homogenization heat treatment and hot rolling of an aluminum alloy ingot by a regular method, then cold rolling and intermediate annealing under predetermined conditions, and then cold rolling (foil rolling) Is included). Here, in the present invention, the foil rolling is performed by polymerization rolling. In the polymerization rolling, two aluminum alloy foils are stacked and supplied to a roll in the final pass and rolled.

  In order to obtain a large number of subgrains in the aluminum alloy foil, it is preferable to make the crystal grain size during the intermediate annealing fine. Therefore, it is preferable that the cold working rate (cold rolling rate) until the intermediate annealing is high, and a cold rolling rate of 30% or more is preferable. In order to improve the strength, it is preferable to set the cold rolling rate to 30% or more. However, if the cold rolling rate until the intermediate annealing exceeds 85%, the effect is saturated and it is not economical, so 85% or less is preferable.

  After intermediate annealing, aluminum alloy foil is made with a high cold rolling rate, and it is necessary to promote sub-graining and particularly to improve the strength. Therefore, the cold rolling rate after intermediate annealing, that is, the final aluminum after intermediate annealing is required. The total cold rolling ratio until the alloy foil (final product) is made is preferably 98.5% or more, and for that purpose, the thickness during intermediate annealing is preferably 1 mm or more. In order to obtain high strength with the aluminum alloy foil, the plate thickness during the intermediate annealing is preferably 1 mm or more. However, if intermediate annealing is performed at a thickness exceeding 2 mm, the strength becomes too high and foil rolling tends to be difficult, so 2 mm or less is preferable. In order to facilitate foil rolling, it is preferable that the work hardening is small at a foil thickness of about 100 μm or less even if the absolute value of the strength is high.

Here, the intermediate annealing is performed in a continuous annealing furnace in order to form 30 or more recrystallized grain sizes in the thickness direction, that is, to set the number of subgrains in the thickness direction to 30 or more. And annealing temperature (attainment temperature) is 380 degreeC or more and 550 degrees C or less, and holding time is 1 minute or less.
When the annealing temperature is less than 380 ° C., recrystallization does not proceed sufficiently, the number of subgrains is insufficient, and the strength is slightly increased. On the other hand, if it exceeds 550 ° C., the effect is saturated and the surface appearance is liable to deteriorate. In addition, the temperature raising / lowering rate may be within the range of conventional methods in continuous annealing, but in batch annealing, precipitation proceeds during heating, and subgrains coalesce and become coarse during foil rolling. As the process proceeds, the number of subgrains will be insufficient. In addition, the degree of work hardening is insufficient and the strength decreases. In the case of continuous annealing, the temperature increase rate is 1 to 100 ° C./second, and the temperature decrease rate is 1 to 500 ° C./second. In the case of batch annealing, the heating rate is 20 to 60 ° C./hour, and the cooling rate is arbitrarily applied to furnace cooling, standing cooling, forced air cooling, and the like, and these conditions are followed.
And although it is preferable that holding time is long for solid solution, since it is a continuous annealing furnace, holding over 1 minute is economically inferior because the line speed becomes remarkably slow.

  Thus, the number of subgrains in the thickness direction can be controlled by the component range, the number of crystal grains during intermediate annealing, and the solid solution state.

  As mentioned above, although the form for implementing this invention has been described, the Example which confirmed the effect of this invention is demonstrated concretely compared with the comparative example which does not satisfy | fill the requirements of this invention below. In addition, this invention is not limited to this Example.

[Sample preparation]
(Example No. 1-10, comparative example No. 11-19)
An aluminum alloy having the composition shown in Table 1 was melted and cast into an ingot, and the ingot was subjected to face grinding, and then subjected to homogenization heat treatment at 540 ° C. for 4 hours. The homogenized ingot is subjected to hot rolling and further cold rolling, and then subjected to intermediate annealing, and after that, under conditions where foil rolling is performed by polymerization rolling to an average value of 12 μm except for a part. Cold-rolled to obtain an aluminum alloy foil. The conditions for the intermediate annealing were an annealing temperature of 450 ° C., a temperature increase rate of 10 ° C./second, a temperature decrease rate of 20 ° C./second, and a holding time of 5 seconds in a continuous annealing furnace. The thickness of the plate (foil) after hot rolling is 3.0 mm, the thickness of the plate (foil) before intermediate annealing is 1.5 mm (50% cold rolling before intermediate annealing, after intermediate annealing) The cold rolling rate (total cold rolling rate): about 99.2%). In Table 1, No. α is based on the aluminum alloy foil based on the description of Patent Document 2 and is listed in Table 1 for convenience because it is used in “evaluation by manufacturing method” described later.

(Example No. 20-25, comparative example No. 26-35)
An aluminum alloy shown in Table 2 (alloys A, C, D, F, and T corresponding to Table 1) was melted and cast to form an ingot. For No. 35, homogenization heat treatment was performed at 520 ° C. for 6 hours, and for others at 540 ° C. for 2 hours. The homogenized ingot is subjected to hot rolling and further cold rolling, and then subjected to intermediate annealing, and after that, under conditions where foil rolling is performed by polymerization rolling to an average value of 12 μm except for a part. Cold-rolled to obtain an aluminum alloy foil. The conditions for intermediate annealing and cold rolling are as shown in Table 2. In the case of continuous annealing (CAL), the rate of temperature increase is 10 ° C./second and the rate of temperature decrease is 20 ° C./second. In the case of batch annealing (BACH), the rate of temperature increase is 40 ° C./hour, the rate of temperature decrease. Was 80 ° C./hour (cooling). The total cold rolling rate is an approximate value.

  The component composition is shown in Table 1, and the production conditions are shown in Table 2. In the table, those not satisfying the scope of the present invention and those not satisfying the production conditions are indicated by underlining the numerical values, and those not containing a component are indicated by “−”. No. No. 35 is based on the aluminum alloy foil based on the description of Patent Document 2, and 27, 31, and 32 are aluminum alloy foils based on the description of Patent Document 2, although the components are different, but the intermediate annealing conditions are different. Moreover, in Table 2, the thickness of the foil after hot rolling is described as hot-rolled end thickness, and the thickness of the foil before intermediate annealing is described as intermediate annealing thickness.

[Number of subgrains]
Next, the number of subgrains in the thickness direction of the aluminum alloy foil was measured by the following method.
First, an aluminum alloy foil is cut to about 5 × 10 mm at a location where the foil thickness is 12 μm, and a conductive tape is used on a thin plate base so that the foil is slightly protruding. Pasted. Next, this foil portion was cut with a FIB (Focused Ion Beam) apparatus so that a parallel section could be observed. Then, the cross section was subjected to EBSD (Electron Back Scatter Diffraction) analysis with a scanning electron microscope at an observation magnification of × 2000, and an orientation mapping image was obtained. Since the observation is usually performed from the surface, the analysis software automatically displays an orientation mapping image of the ND plane viewed from the surface. In this analysis, it was parallel cross-section (RD-TD plane) observation, and it rotated so that the orientation mapping image of the ND plane seen from the RD-ND plane could be obtained. Based on this orientation mapping image, the number of subgrains was calculated by the line segment method.
The results are shown in Tables 1 and 2.

  Here, sub-grains have an inclination angle between crystal grains of 15 ° or less, and the same sub-grains have the same color. The relationship between color and crystal orientation is shown in the color code. In addition, the subgrain has an inclination angle between crystal grains of 0 to 15 °, but 0 ° has the darkest color and 15 ° has the lightest color. Then, in consideration of the above matters, the subgrains were counted in the azimuth mapping diagram by visual judgment. In addition, although the number of subgrains is slightly different depending on the location, the number of subgrains is measured here in the thickness direction.

[Evaluation]
The following evaluation was performed with the obtained aluminum alloy foil.
(Strength and elongation)
Tensile strength and elongation were measured using a B-type test piece according to the Light Metal Association Standard LIS AT5. That is, a strip-shaped test piece of 15 mm width × about 200 mm length was cut out from the aluminum alloy foil so that the tensile direction was parallel to the rolling direction, and the distance between the chucks was set to 100 mm. For the test, Tentecron Universal Testing Machine Model: RTC-1225A manufactured by Orientec Co., Ltd. was used. In this test, tensile strength and elongation were measured. The acceptance criteria for strength was a tensile strength of 280 to 350 MPa, and the acceptance criteria for elongation was 1.0% or more.

  These results are shown in Tables 1 and 2. In the table, those whose number of subgrains does not meet the scope of the present invention, those whose tensile strength and elongation do not meet the acceptance criteria are underlined in the numerical value, and aluminum alloy foil cannot be manufactured. Those that could not be evaluated are indicated by “−”.

(Evaluation with aluminum alloy foil)
As shown in Table 1, the example No. Since 1-10 satisfy | fill the range of this invention, intensity | strength and elongation were excellent.

On the other hand, No. which is a comparative example. Since 11 to 19 did not satisfy the scope of the present invention, the following results were obtained.
No. No. 11, since the Si content exceeds the upper limit, a large number of Al-Mn-Si intermetallic compounds are formed, and recrystallization is inhibited, so that the crystal grain size becomes coarse and the subgrain number is less than the lower limit. became. Therefore, the growth was inferior. No. No. 12 was low in tensile strength and inferior in strength because the Mn content was less than the lower limit.

No. In No. 13, since the Fe content was less than the lower limit, the crystal grain size was coarse and the subgrain number was less than the lower limit. Therefore, the growth was inferior. Moreover, the tensile strength was low and the strength was poor. No. In No. 14, since the Fe content exceeded the upper limit value, a coarse intermetallic compound was produced, and hole damage occurred during foil rolling. Therefore, foil rolling could not be continued.
No. No. 15 had a lower Cu content and a lower strength because the Cu content was less than the lower limit. No. In No. 16, since the Cu content exceeded the upper limit, the strength was too high, the foil rollability was lowered, and the film could not be rolled to a thickness of 12 μm.

No. In No. 17, since the Mn content was less than the lower limit, the tensile strength was low and the strength was poor. No. In No. 18, since the Mn content exceeded the upper limit, a coarse intermetallic compound was produced, the foil rollability was lowered, and the film could not be rolled to a thickness of 12 μm.
No. In No. 19, since the Mg content exceeded the upper limit, the strength was too high, the foil rollability was lowered, and the film could not be rolled to a thickness of 12 μm.

(Evaluation by manufacturing method)
As shown in Table 2, the example No. Since 20-25 satisfy | fill the range of this invention, intensity | strength and elongation were excellent.

On the other hand, No. which is a comparative example. Since 26 to 35 did not satisfy the scope of the present invention, the following results were obtained.
No. In No. 26, since the intermediate annealing was a batch type, fine crystal grains were not obtained at the time of intermediate annealing, and subgrains grew and coalesced at the time of foil rolling, and a sufficient number was not obtained. Also, the degree of work hardening was insufficient. Furthermore, the intermediate annealing thickness and the total cold rolling rate were insufficient. For these reasons, the tensile strength was low, the strength was poor, the subgrain number was less than the lower limit value, and the elongation was poor. No. In No. 27, the intermediate annealing thickness and the total cold rolling rate were insufficient, so the tensile strength was low and the strength was inferior. No. In No. 28, since the intermediate annealing was a batch type, fine crystal grains were not obtained during the intermediate annealing. Therefore, subgrains grew and coalesced during foil rolling, and a sufficient number could not be obtained, and the number of subgrains was less than the lower limit value, resulting in poor elongation. Further, the degree of work hardening was insufficient, the tensile strength was low, and the strength was inferior.

  No. In No. 29, since the intermediate annealing thickness was too thick, the foil rollability deteriorated and could not be rolled to a thickness of 12 μm. Moreover, since the ultimate temperature was too high, a surface pattern was generated during the manufacturing process. The total cold rolling rate is a value at the time when rolling is completed. No. In No. 30, the ultimate temperature was too low, so recrystallization did not occur during intermediate annealing, and the subgrain number was less than the lower limit. Therefore, the growth was inferior. Moreover, the tensile strength became slightly high. In addition, since the height of the tensile strength was slightly higher than the upper limit value of the present invention, it was possible to barely roll to a thickness of 12 μm. No. No. 31 had a low tensile strength and an inferior strength because the intermediate annealing thickness and the total cold rolling rate were insufficient.

  No. In No. 32, the intermediate annealing thickness and the total cold rolling rate were insufficient, so the tensile strength was low and the strength was inferior. No. Since the ultimate temperature of No. 33 was too low, it was not recrystallized by intermediate annealing, and the subgrain number was less than the lower limit. Therefore, the growth was inferior. Moreover, the tensile strength became slightly high. In addition, since the height of the tensile strength was slightly higher than the upper limit value of the present invention, it was possible to barely roll to a thickness of 12 μm. No. No. 34 had an insufficient cold rolling rate until intermediate annealing, so the crystal grain size was coarse and the subgrain number was less than the lower limit. Therefore, the growth was inferior. Moreover, the tensile strength was low and the strength was poor. No. Although No. 35 is an aluminum alloy foil based on the description of Patent Document 2 which is a conventional technique, the number of subgrains was less than the lower limit value, but the elongation was inferior although it was excellent in strength.

  As described above, the aluminum alloy hard foil for battery current collector according to the present invention has been described in detail with reference to the embodiment and examples, but the gist of the present invention is not limited to the above-described contents. Needless to say, the contents of the present invention can be widely modified and changed based on the above description.

Claims (3)

An aluminum alloy hard foil for a battery current collector manufactured by polymerization rolling,
Mn: 0.8 to 1.5% by mass, Cu: 0.05 to 0.20% by mass, Fe: 0.3 to 0.7% by mass, with the balance consisting of Al and inevitable impurities,
The thickness of the aluminum alloy hard foil for the battery current collector is 9 to 15 μm,
There are 30 or more subgrains in the thickness direction,
An aluminum alloy hard foil for a battery current collector, having a tensile strength of 280 to 350 MPa and an elongation of 1.0% or more.   The aluminum alloy hard foil for a battery current collector according to claim 1, further comprising at least one of Mg: 0.2 mass% or less and Si: 0.6 mass% or less.   The aluminum alloy hard for battery current collector according to claim 1 or 2, further comprising at least one of Cr: 0.2 mass% or less and Zn: 0.3 mass% or less. Foil.