WO2016017380A1

WO2016017380A1 - Aluminum plate

Info

Publication number: WO2016017380A1
Application number: PCT/JP2015/069619
Authority: WO
Inventors: 順二川口
Original assignee: 富士フイルム株式会社
Priority date: 2014-07-31
Filing date: 2015-07-08
Publication date: 2016-02-04
Also published as: TW201608582A

Abstract

The present invention addresses the issue of providing an aluminum plate having a plurality of fine through-holes and having a high tensile strength. The aluminum plate having a plurality of through-holes in the thickness direction has an average thickness of no more than 50 µm, an aluminum purity of 85.00%-99.90%, an average through-hole opening diameter of 1-100 µm, and an average opening ratio of 1%-40%.

Description

Aluminum plate

The present invention relates to an aluminum plate used for a current collector for an electricity storage device.

In recent years, with the development of portable devices such as personal computers and mobile phones, hybrid cars, electric cars, etc., there is a demand for power storage devices as their power sources, especially lithium ion capacitors, lithium ion secondary batteries, and electric double layer capacitors. It is increasing.

It is known that an aluminum plate is used as an electrode current collector (hereinafter simply referred to as “current collector”) used for the positive electrode or the negative electrode of such an electricity storage device. It is also known that an active material such as activated carbon is applied to the surface of a current collector made of an aluminum plate and used as a positive electrode or a negative electrode.

For example, Patent Document 1 describes using a metal foil having a plurality of through-holes as a current collector, and describes aluminum, copper, and the like as its material. One side of this metal foil Alternatively, an electrode having an active material layer on both surfaces is described ([claim 1] [0021]).
Patent Document 2 describes that a current collector in the form of a film having through holes is used as the current collector, and aluminum, stainless steel, or the like is used as the positive electrode current collector. In addition, an electrode having the current collector and the active material is described ([claim 1] [0053]).
Patent Document 3 describes a metal foil in which a large number of through holes are formed at locations where an active material is attached as a positive and negative electrode plate, and an aluminum foil as a positive electrode current collector. In addition, an electrode in which an active material mixture is applied to the metal foil is described ([claim 1] [0016]).
Patent Document 4 describes that an aluminum through foil is used as the current collector, and describes that an active material is applied to the aluminum through foil ([Claim 1] [Claim 1] 0036]).

In such a current collector, the through hole is formed to facilitate the movement of lithium ions, but it is also known that having a large number of through holes improves the adhesion to the active material. It has been. If this through-hole is too large, the coating property of the active material is lowered, the surface of the coated active material is dented, the uniformity is impaired, or the strength of the current collector is lowered. Therefore, through-holes are formed finely, and the aperture ratio is controlled so that the adhesion between the current collector and the active material, the coating properties of the active material, the uniformity of the active material surface, the strength of the current collector, etc. It is known to improve.

For example, in Patent Document 1, by setting the minimum hole diameter of the through hole in the range of 0.01 to 0.19 mm, the adhesive strength with the active material layer is increased, and the pattern of the through hole is that of the active material layer. It is described that the surface roughness of the active material layer is reduced by suppressing reflection on the surface ([0022]).
Patent Document 2 describes that the strength of the current collector is prevented from being reduced by setting the aperture ratio to 5 to 79% ([0066]).
Patent Document 3 discloses that an active material mixture is applied to a metal foil by setting each area of the through-hole to 8 × 10 ⁻⁷ m ² or less and an opening ratio in a range of 5% to 55%. ([0081]).
Patent Document 4 describes that the adhesion between the current collector and the active material is improved by setting the surface area enlargement ratio to a value of 0.15 × foil thickness t (μm) or more. ([0037]).

Further, such fine through holes are formed by electrolytic etching as described in, for example, Patent Document 4 ([0052]).

JP 2013-077774 A JP 2012-151395 A JP 2010-186777 A International Publication No. 2011/004777

In Patent Document 4, high-purity aluminum is used in order to form fine through holes by electrolytic etching ([Claim 1]).
However, as a result of studies by the present inventors, it has been found that there is a problem that the strength is poor when a high-purity aluminum plate is used.

Therefore, an object of the present invention is to provide an aluminum plate having a large number of fine through holes and having a high tensile strength.

As a result of intensive studies to achieve the above object, the present inventors have found that the average thickness is 50 μm or less, the purity of aluminum is 85% to 99.90%, the average opening diameter of the through holes is 1 μm to 100 μm, and the average opening It was found that by using an aluminum plate with a rate of 1% to 40%, it was possible to have a large number of fine through holes and a high tensile strength, and the present invention was completed.
That is, it has been found that the above object can be achieved by the following configuration.

[1] In an aluminum plate having a plurality of through holes in the thickness direction,
The average thickness is 50 μm or less, the purity of aluminum is 85% to 99.90%,
An aluminum plate having an average opening diameter of through holes of 1 μm to 100 μm and an average opening ratio of 1% to 40%.
[2] The aluminum plate according to [1], wherein the purity of aluminum is 90% to 99.80%.
[3] The aluminum plate according to [1] or [2], wherein the average opening diameter of the through holes is 1 μm to 60 μm.
[4] The aluminum plate according to any one of [1] to [3], wherein the average opening ratio of the through holes is 5% to 30%.
[5] The aluminum plate according to any one of [1] to [4], which has a metal layer made of metal plating that covers at least the inner surface of the through hole.

As described below, according to the present invention, an aluminum plate having a large number of fine through holes and having a high tensile strength can be provided.

1A is a top view conceptually showing an example of the aluminum plate of the present invention, and FIG. 1B is a cross-sectional view taken along the line BB of FIG. 1A. ) Is a schematic cross-sectional view showing an electrode using FIG. 1A as a current collector. FIG. 2 is a schematic cross-sectional view showing another example of the aluminum plate of the present invention. 3 (A) to 3 (E) are schematic cross-sectional views for explaining an example of a preferred method for producing the aluminum plate of the present invention, and FIG. 3 (A) is a schematic view of an aluminum substrate. FIG. 3B is a schematic cross-sectional view showing a state in which the oxide film is formed on the surface of the aluminum base material, and FIG. 3C is a schematic cross-sectional view of the oxide film formation. FIG. 3D is a schematic cross-sectional view showing a state in which an electrochemical dissolution process is performed after the treatment and through holes are formed in the aluminum base material and the oxide film. FIG. 3D is a diagram illustrating the oxide film after the electrochemical dissolution process. FIG. 3E is a schematic cross-sectional view showing the state after the electrochemical roughening treatment is performed after removing the oxide film. is there. 4 (A) to 4 (E) are schematic cross-sectional views for explaining another example of a preferred method for producing an aluminum plate of the present invention, and FIG. 4 (A) shows an aluminum substrate. FIG. 4B is a schematic cross-sectional view showing a state in which an oxide film is formed on the aluminum base, and the oxide film is formed on the front and back surfaces. FIG. FIG. 4 is a schematic cross-sectional view showing a state in which an electrochemical dissolution process is performed after the oxide film formation process and through holes are formed in the aluminum base material and the oxide film, and FIG. FIG. 4E is a schematic cross-sectional view showing a state after the oxide film is removed later, and FIG. 4E is a schematic view showing a state after the electrochemical roughening treatment is performed after the oxide film is removed. FIG.

Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Aluminum plate]
The aluminum plate of the present invention has an average thickness of 50 μm or less, an aluminum purity of 85% to 99.90%, an average opening diameter of through holes of 1 μm to 100 μm, and an average opening ratio of 1% to 40%. It is a board.
Next, the structure of the aluminum plate of the present invention will be described with reference to FIGS. 1 (A) to 1 (C).

FIG. 1 (A) is a schematic top view showing an example of a preferred embodiment of the aluminum plate of the present invention, and FIG. 1 (B) is a cross-sectional view taken along the line BB of FIG. 1 (A). FIG. 1C is a schematic cross-sectional view showing an example of an electrode using the aluminum plate 10 shown in FIG. 1A as a current collector of an electricity storage device.
As shown in FIGS. 1 (A) and 1 (B), the aluminum plate 10 is formed by forming a plurality of through holes 5 in an aluminum base 3.
An electrode 30 shown in FIG. 1C is formed by laminating an active material layer 32 on one surface of the aluminum plate 10 shown in FIG.

The plurality of through holes 5 formed in the aluminum base 3 have an average opening diameter of 1 μm to 100 μm and an average opening ratio of 1% to 40%.
The aluminum substrate 3 is aluminum having a purity of 85% to 99.90% and an average thickness of 50 μm or less.
Here, the average opening diameter of the through-holes was obtained by photographing the surface of the aluminum plate at a magnification of 200 times from directly above using a high-resolution scanning electron microscope (SEM). At least 20 through-holes were extracted, and the diameter was read as the opening diameter, and the average value of these was calculated as the average opening diameter.
In addition, the diameter measured the maximum value of the distance between the edge parts of a through-hole part.
Further, the average aperture ratio of the through-holes was obtained by photographing the surface of the aluminum plate at a magnification of 200 times from directly above using a high resolution scanning electron microscope (SEM), and a 30 mm × 30 mm visual field (5 ), Binarize with image analysis software, etc., and observe the through-hole part and the non-through-hole part. From the total of the opening area of the through-hole and the area of the visual field (geometric area), Calculated from the geometric area), and the average value in each field of view (5 locations) was calculated as the average aperture ratio.
Moreover, the purity of aluminum was measured based on the emission spectroscopic analysis method of JIS H 1305: 2005 aluminum and aluminum alloy.

In the present invention, the average opening diameter of the through-holes 5 is a fine diameter of 1 μm to 100 μm, the average opening ratio is 1% to 40%, and the purity of aluminum is in the range of 85.00% to 99.90%. As a result, a thin base material having an average thickness of 50 μm or less can have a sufficient tensile strength even if it has a large number of through holes. In addition, by setting the average opening diameter and the average opening ratio of the through holes 5 within this range, it is possible to improve the coating property of the coating applied to the surface of the aluminum plate 10 and to improve the uniformity of the layer formed by coating. The adhesion with the formed layer can be improved.

For example, when the aluminum plate 10 is used as a current collector of a lithium ion capacitor, the average opening diameter of the through holes 5 is set to 1 μm to 100 μm, and the average opening ratio is set to 1% to 40%. Lithium can be pre-doped, and lithium can be more uniformly dispersed. In addition, when the active material layer 32 is formed on the surface of the aluminum plate 10 that is a current collector, like the electrode 30 shown in FIG. 1C, the active material coating property and the aluminum plate 10 and the active material layer 32 are formed. And the uniformity of the surface of the formed active material layer 32 can be improved, so that an electricity storage device having excellent cycle characteristics can be manufactured.

Further, by setting the purity of aluminum within the above range and the average opening diameter and average opening ratio of the through holes within the above range, the tensile strength is 15 N / mm ² or more, preferably 20 N / mm ² or more, more preferably. Can realize a tensile strength of 60 N / mm ² or more.
The tensile strength is a tensile strength in a tensile test based on JIS Z2241: 2011. Specifically, a sample having a width of 25 mm and a length of 150 mm was fixed so that the distance between chucks was 70 mm, measured 10 times at a tensile speed of 10 mm / min, and the average value was taken as the tensile strength.

The average opening diameter of the through holes is preferably 1 μm to 60 μm, more preferably 1 μm to 50 μm, particularly preferably 1 to 40 μm, and further preferably 10 to 40 μm, from the viewpoints of the above-described coating properties, adhesion, and tensile strength.
In addition, the average opening ratio of the through holes is preferably 5% to 30%, more preferably 5% to 25%, and particularly preferably more than 5% and 20% or less from the viewpoints of the above-described applicability, adhesion, and tensile strength. preferable.

Further, the purity of aluminum is preferably in the range of 90% to 99.80%, more preferably in the range of 92% to 99.70%, still more preferably in the range of 95% to 99.50%, from the viewpoint of the tensile strength. % Or more and less than 98.50% is particularly preferable.
The average thickness of the aluminum plate is preferably 5 μm to 50 μm, more preferably 10 μm to 50 μm.
By setting the thickness of the aluminum plate to 5 μm or more, it is possible to suppress breakage due to insufficient strength. Further, when the thickness is 50 μm or less, an increase in volume can be suppressed, space saving can be achieved, and a penetration process can be facilitated.
In addition, the average thickness of the aluminum plate measured the thickness of five points within 100 mm x 100 mm, and made it the average value.

In the illustrated example, the plurality of through holes are regularly formed. However, the plurality of through holes may be irregularly formed as long as the average opening diameter and the average opening ratio satisfy the above ranges.

Further, the surface of the aluminum plate 10 may be roughened. For example, it is preferable that concave portions having an average opening diameter of 0.5 μm to 3.0 μm are formed at a density of 10/100 μm ² or more. By roughening the surface of the aluminum plate, the adhesion to the active material layer is improved, and the contact area increases by increasing the surface area, so the capacity of the electricity storage device using the aluminum plate (current collector) is maintained. The rate is high.
The roughening treatment method is not particularly limited, and a known roughening treatment method can be used as appropriate. For example, the surface is preferably roughened by an electrochemical surface roughening treatment described later.

Further, in the example shown in FIG. 1B, the aluminum base 3 is configured to have a plurality of through holes 5, but the present invention is not limited to this, and at least covers the inner surface of the through holes. You may have the metal layer which consists of metal plating.
FIG. 2 is a schematic cross-sectional view showing another example of the aluminum plate of the present invention.
An aluminum plate 10 shown in FIG. 2 includes first and

second metal layers

6 and 2 made of a metal or alloy other than aluminum on the front and back surfaces of the aluminum base 3 having through holes and the inner surface (inner wall) of the through holes 5. In this embodiment, the metal layer 7 is provided.
Thus, by forming the metal layer on the inner surface of the through hole, the average opening diameter of the through hole can be suitably adjusted to a small range of about 1 μm to 20 μm.
Such a metal layer can be formed by a metal coating process described later.
In the illustrated example, the metal layer is formed on the front and back surfaces of the aluminum base 3 and the inner surface of the through hole 5. However, the present invention is not limited to this, and at least a metal is formed on the inner surface of the through hole 5. A layer may be formed.

<Aluminum substrate>
The aluminum substrate is not particularly limited as long as it has a thickness of 50 μm or less and the purity of aluminum is 85% to 99.90%, and a known aluminum substrate can be used. That is, the aluminum substrate is an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements.
For example, JIS H-4160, alloy numbers: A1085H-H18, A1070H-H18, A1050H-H18, A1100H-H18, A1N30H-H18, A3003H-H18, A3004H-H18, A8021H-H18, A8079H-H18 Etc. can be used.

<Active material layer>
There is no limitation in particular as an active material layer, The well-known active material layer used in the conventional electrical storage device can be utilized.
Specifically, regarding an active material and a conductive material, a binder, a solvent, and the like that may be contained in the active material layer when an aluminum plate is used as a positive electrode current collector, JP 2012-216513 A The materials described in the paragraphs [0077] to [0088] can be adopted as appropriate, the contents of which are incorporated herein by reference.
In addition, as an active material when an aluminum plate is used as a negative electrode current collector, the materials described in paragraph [0089] of JP2012-216513A can be appropriately employed, and the contents thereof are described in this specification. Incorporated into the book as a reference.

[Power storage device]
An electrode using the aluminum plate of the present invention as a current collector can be used as a positive electrode or a negative electrode of an electricity storage device.
Here, regarding the specific configuration of the electricity storage device (particularly the secondary battery) and the application to which it is applied, the materials and applications described in paragraphs [0090] to [0123] of JP2012-216513A are appropriately used. Which is incorporated herein by reference.

Further, in the example shown in FIG. 1C, a configuration in which the aluminum plate of the present invention is used as a current collector is shown, but the aluminum plate of the present invention can be used for other purposes. For example, it can be suitably used for heat resistant fine particle filters, sound absorbing materials, and the like.

[Aluminum plate manufacturing method]
Next, the manufacturing method of the aluminum plate of this invention is demonstrated.
The method for producing an aluminum plate is a method for producing an aluminum plate having an aluminum substrate having a plurality of through-holes in the thickness direction, wherein the surface of the aluminum substrate having an average thickness of 50 μm or less is subjected to an oxide film forming treatment and oxidized. An oxide film forming process for forming a film, an electrochemical dissolution process (hereinafter also referred to as “electrolytic dissolution process”) after the oxide film forming process to form a through hole, and an aluminum plate And an oxide film removing step for removing the oxide film.

In the present invention, by having the oxide film forming step, the through-hole forming step, and the oxide film removing step, the coating property of the active material and the adhesion with the active material layer are good, and the uniformity of the active material layer surface is improved. An aluminum plate that can be improved and can be suitably used for a current collector having sufficient tensile strength can be manufactured.
Although this is not clear in detail, the present inventors presume as follows.
That is, starting from the intermetallic compound existing at the surface of the aluminum substrate or at the interface between the aluminum substrate and the oxide film, defects in the oxide film generated by the oxide film formation process, uneven shape, etc. Since through-holes can be easily formed by electrolytic dissolution treatment, even when aluminum having a purity of 85.00% to 99.90% is used, fine through-holes having an average opening diameter of 1 μm to 100 μm are formed. It is considered possible.

Next, each step of the aluminum plate manufacturing method will be described with reference to FIGS. 3 (A) to 3 (E) and FIGS. 4 (A) to 4 (E).

3 (A) to 3 (E) and FIGS. 4 (A) to 4 (E) are schematic cross-sectional views showing an example of a preferred embodiment of a method for producing an aluminum plate.
As shown in FIGS. 3 (A) to 3 (E) and FIGS. 4 (A) to 4 (E), the manufacturing method of the aluminum plate is the surface of the aluminum substrate 1 (the surface in the embodiment shown in FIG. 4). And an oxide film formation process (FIGS. 3A and 3B, FIG. 4A and FIG. 4B) for performing an oxide film formation process on the back surface and forming an oxide film 2, After the oxide film forming step, electrolytic dissolution treatment is performed to form the through hole 5, and a through hole forming step for producing an aluminum plate having the aluminum substrate 3 having the through hole and the oxide film 4 having the through hole (FIG. 3 ( B), FIG. 3 (C), FIG. 4 (B) and FIG. 4 (C)), and after the through hole forming step, the oxide film 4 having the through hole is removed, and the aluminum substrate 3 having the through hole is removed. Oxide film removing step (FIG. 3C) and FIG. D), is a manufacturing method having the FIG. 4 (C) and FIG. 4 (D)), a.
In addition, the aluminum plate manufacturing method is such that after the oxide film removal step, the aluminum substrate 3 having a through hole is subjected to an electrochemical surface roughening treatment to produce a roughened aluminum plate 10. It preferably has processing steps (FIG. 3D and FIG. 3E, FIG. 4D and FIG. 4E).

[Oxide film formation process]
The oxide film forming step of the manufacturing method of the present invention is a step of forming an oxide film by performing an oxide film forming process on the surface of an aluminum substrate having an average thickness of 50 μm or less.

<Oxide film formation treatment>
The oxide film forming process is not particularly limited, and for example, a process similar to a conventionally known anodizing process can be performed.
As the anodizing treatment, for example, conditions and apparatuses described in paragraphs [0063] to [0073] of JP2012-216513A can be appropriately employed.

In the present invention, conditions for anodizing treatment vary depending on the electrolyte used, and thus cannot be determined unconditionally. However, in general, the electrolyte concentration is 1 to 80% by mass, the solution temperature is 5 to 70 ° C., It is appropriate that the current density is 0.5 to 60 A / dm ² , the voltage is 1 to 100 V, and the electrolysis time is 1 second to 20 minutes, which are adjusted to obtain a desired amount of oxide film.

In the present invention, an anodizing treatment performed in a sulfuric acid solution is preferable.
When anodizing is performed in an electrolytic solution containing sulfuric acid, direct current may be applied between the aluminum substrate and the counter electrode, or alternating current may be applied. When direct current is applied to the aluminum substrate, the current density is preferably 1 to 60 A / dm ² , and more preferably 5 to 40 A / dm ² . When the anodizing treatment is continuously performed, it is preferable that the anodization is performed by a liquid power feeding method in which power is supplied to the aluminum base material through the electrolytic solution.

In the present invention, the amount of the oxide film formed by the anodic oxidation treatment is preferably 0.05 to 50 g / m ² , and more preferably 0.1 to 10 g / m ² .

[Through hole forming process]
The through hole forming step is a step of forming a through hole by performing electrolytic dissolution treatment after the oxide film forming step.

<Electrolytic dissolution treatment>
The electrolytic dissolution treatment is not particularly limited, and direct current or alternating current can be used, and an acidic solution can be used as the electrolytic solution. Among these, it is preferable to use an electrolytic solution mainly composed of hydrochloric acid or nitric acid.

In the present invention, the acidic solution as the electrolytic solution includes, in addition to nitric acid and hydrochloric acid, U.S. Pat. Nos. 4,671,859, 4,661,219, 4,618,405, 4,600,482, 4,566,960, 4,566,958, 4,566,959, 4,416,972, 4,374, Electrolytic solutions described in the specifications of Nos. 710, 4,336,113, and 4,184,932 can also be used.

The concentration of the acidic solution is preferably 0.5 to 2.5% by mass, particularly preferably 0.7 to 2.0% by mass. The liquid temperature of the acidic solution is preferably 20 to 80 ° C., more preferably 30 to 60 ° C.

An aqueous solution mainly composed of hydrochloric acid or nitric acid is an aqueous solution of hydrochloric acid or nitric acid having a concentration of 1 to 100 g / L, nitric acid compounds having nitrate ions such as aluminum nitrate, sodium nitrate, ammonium nitrate, aluminum chloride, sodium chloride, ammonium chloride. It is possible to add at least one hydrochloric acid compound having a hydrochloric acid ion such as 1 g / L to saturation.
Moreover, the metal contained in aluminum alloys, such as iron, copper, manganese, nickel, titanium, magnesium, a silica, may melt | dissolve in the aqueous solution which has hydrochloric acid or nitric acid as a main component. Preferably, a solution obtained by adding aluminum chloride, aluminum nitrate or the like to an aqueous solution of hydrochloric acid or nitric acid having a concentration of 0.5 to 2% by mass so that aluminum ions are 3 to 50 g / L is preferably used.

In the electrochemical dissolution treatment, a direct current is mainly used, but when an alternating current is used, the alternating current power wave is not particularly limited, and a sine wave, a rectangular wave, a trapezoidal wave, a triangular wave, etc. are used. Among these, a rectangular wave or a trapezoidal wave is preferable, and a trapezoidal wave is particularly preferable.

(Nitric acid electrolysis)
In the present invention, an average opening diameter of 1 μm to 100 μm is easily obtained by an electrochemical dissolution process (hereinafter also referred to as “nitric acid dissolution process”) using an electrolytic solution mainly composed of nitric acid, and an average aperture ratio. Through-holes with an amount of 1% to 40% can be formed.
Here, the nitric acid dissolution treatment uses direct current, the average current density is 5 A / dm ² or more, and the amount of electricity is 50 C / dm ² or more because it is easy to control the dissolution point of through-hole formation. It is preferable that the electrolytic treatment is performed in step (b). The average current density is preferably 100 A / dm ² or less, and the quantity of electricity is preferably 10,000 C / dm ² or less.
In addition, the concentration and temperature of the electrolytic solution in nitric acid electrolysis are not particularly limited, and electrolysis is performed at a high concentration, for example, 30 to 60 ° C. using a nitric acid electrolytic solution having a nitric acid concentration of 15 to 35% by mass, Electrolysis can be carried out at a high temperature, for example, at 80 ° C. or higher, using a 7-2 mass% nitric acid electrolyte.

(Hydrochloric acid electrolysis)
In the present invention, an average opening diameter of 1 to 100 μm is easily obtained by an electrochemical dissolution treatment (hereinafter also referred to as “hydrochloric acid dissolution treatment”) using an electrolytic solution mainly composed of hydrochloric acid. A through hole having a rate of 1 to 40% can be formed.
Here, the hydrochloric acid dissolution treatment uses direct current, the average current density is 5 A / dm ² or more, and the amount of electricity is 50 C / dm ² or more because it is easy to control the dissolution point of through-hole formation. It is preferable that the electrolytic treatment is performed in step (b). The average current density is preferably 100 A / dm ² or less, and the quantity of electricity is preferably 10,000 C / dm ² or less.
Further, the concentration and temperature of the electrolytic solution in hydrochloric acid electrolysis are not particularly limited, and electrolysis is performed at 30 to 60 ° C. using a hydrochloric acid electrolytic solution having a high concentration, for example, a hydrochloric acid concentration of 10 to 35% by mass, or a hydrochloric acid concentration of 0. Electrolysis can be performed at a high temperature, for example, 80 ° C. or higher, using a 7-2 mass% hydrochloric acid electrolyte.

In the present invention, since the average opening diameter of the through holes can be 5 μm or more and the opening ratio can be adjusted to 5% or more, the amount of electricity (Q) C / dm ² and the electrolytic dissolution in the electrolytic dissolution treatment are adjusted. The total thickness (t) μm of the oxide film and the aluminum substrate when the treatment is performed preferably satisfies the following formula (I), and more preferably satisfies the following formula (II).
5 ≦ Q / t ≦ 300 (I)
10 ≦ Q / t ≦ 300 (II)
This is considered to be because, when the above formula (I) is satisfied, the elution of the oxide film and the aluminum base material by the electrolytic dissolution treatment is in a suitable state with respect to the thickness.
In the present invention, the total thickness (t) of the oxide film and the aluminum base material when the electrolytic dissolution treatment is performed is basically the thickness of the aluminum base material before the above-described oxide film formation processing is performed. The same value as

[Oxide film removal process]
The oxide film removing step is a step of removing the oxide film.
In the oxide film removing step, for example, the oxide film can be removed by performing an acid etching process or an alkali etching process described later.

<Acid etching treatment>
The dissolution treatment is a treatment for dissolving the oxide film using a solution (hereinafter referred to as “alumina solution”) that preferentially dissolves the oxide film (aluminum oxide) over aluminum.

Here, as the alumina solution, for example, chromium compound, nitric acid, sulfuric acid, phosphoric acid, zirconium compound, titanium compound, lithium salt, cerium salt, magnesium salt, sodium fluorosilicate, zinc fluoride, manganese compound, molybdenum An aqueous solution containing at least one selected from the group consisting of a compound, a magnesium compound, a barium compound and a halogen simple substance is preferable.

Specifically, examples of the chromium compound include chromium (III) oxide and anhydrous chromium (VI) acid.
Examples of the zirconium-based compound include zircon ammonium fluoride, zirconium fluoride, and zirconium chloride.
Examples of the titanium compound include titanium oxide and titanium sulfide.
Examples of the lithium salt include lithium fluoride and lithium chloride.
Examples of the cerium salt include cerium fluoride and cerium chloride.
Examples of the magnesium salt include magnesium sulfide.
Examples of the manganese compound include sodium permanganate and calcium permanganate.
Examples of the molybdenum compound include sodium molybdate.
Examples of magnesium compounds include magnesium fluoride pentahydrate.
Examples of barium compounds include barium oxide, barium acetate, barium carbonate, barium chlorate, barium chloride, barium fluoride, barium iodide, barium lactate, barium oxalate, barium perchlorate, barium selenate, selenite. Examples thereof include barium, barium stearate, barium sulfite, barium titanate, barium hydroxide, barium nitrate, and hydrates thereof.
Among the barium compounds, barium oxide, barium acetate, and barium carbonate are preferable, and barium oxide is particularly preferable.
Examples of halogen alone include chlorine, fluorine, and bromine.

Among them, the alumina solution is preferably an aqueous solution containing an acid. Examples of the acid include sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, and the like, and a mixture of two or more acids may be used.
The acid concentration is preferably 0.01 mol / L or more, more preferably 0.05 mol / L or more, and still more preferably 0.1 mol / L or more. There is no particular upper limit, but generally it is preferably 10 mol / L or less, more preferably 5 mol / L or less.

The dissolution treatment is performed by bringing the aluminum base material on which the oxide film is formed into contact with the above-described alumina solution. The method of making it contact is not specifically limited, For example, the immersion method and the spray method are mentioned. Of these, the dipping method is preferred.

The dipping method is a treatment in which an aluminum base material on which an oxide film is formed is dipped in the above-described alumina solution. Stirring during the dipping process is preferable because a uniform process is performed.
The dipping treatment time is preferably 10 minutes or longer, more preferably 1 hour or longer, and further preferably 3 hours or longer and 5 hours or longer.

<Alkaline etching treatment>
The alkali etching treatment is a treatment for dissolving the surface layer by bringing the oxide film into contact with an alkaline solution.

Examples of the alkali used in the alkaline solution include caustic alkali and alkali metal salts. Specifically, examples of caustic alkali include caustic soda and caustic potash. Examples of the alkali metal salt include alkali metal silicates such as sodium metasilicate, sodium silicate, potassium metasilicate, and potassium silicate; alkali metal carbonates such as sodium carbonate and potassium carbonate; sodium aluminate and alumina. Alkali metal aluminates such as potassium acid; alkali metal aldones such as sodium gluconate and potassium gluconate; dibasic sodium phosphate, dibasic potassium phosphate, tribasic sodium phosphate, tertiary potassium phosphate, etc. An alkali metal hydrogen phosphate is mentioned. Among these, a caustic alkali solution and a solution containing both a caustic alkali and an alkali metal aluminate are preferable from the viewpoint of high etching rate and low cost. In particular, an aqueous solution of caustic soda is preferable.

The concentration of the alkaline solution is preferably from 0.1 to 50% by mass, and more preferably from 0.5 to 10% by mass. When aluminum ions are dissolved in the alkaline solution, the concentration of aluminum ions is preferably 0.01 to 10% by mass, and more preferably 0.1 to 3% by mass. The temperature of the alkaline solution is preferably 10 to 90 ° C. The treatment time is preferably 1 to 120 seconds.

Examples of the method of bringing the oxide film into contact with the alkaline solution include, for example, a method in which an aluminum base material on which an oxide film is formed is passed through a tank containing an alkali solution, and an aluminum base material on which an oxide film is formed is applied to an alkaline solution. Examples thereof include a method of immersing in an enclosed tank and a method of spraying an alkaline solution onto the surface (oxide film) of an aluminum substrate on which an oxide film is formed.

[Roughening treatment process]
The optional roughening treatment step that the aluminum plate production method of the present invention may have is an electrochemical roughening treatment (hereinafter referred to as “electrolytic roughening”) on the aluminum substrate from which the oxide film has been removed. This is also a process of roughening the surface or back surface of the aluminum base material.
As described above, by performing electrolytic surface roughening treatment and roughening the surface of the aluminum substrate, the adhesion with the layer containing the active material is improved, and the contact area is increased by increasing the surface area. The capacity retention rate of the electricity storage device using the aluminum plate (current collector) obtained by the production method of the present invention is increased.
As the electrolytic surface-roughening treatment, for example, conditions and apparatuses described in paragraphs [0041] to [0050] of JP2012-216513A can be appropriately employed.

<Nitric acid electrolysis>
In the present invention, a concave portion having an average opening diameter of 0.5 μm to 3.0 μm can be easily formed by an electrochemical surface roughening treatment (hereinafter also referred to as “nitric acid electrolysis”) using an electrolytic solution mainly composed of nitric acid. It can be formed at a density of 10 pieces / 100 μm ² or more.
Here, nitric acid electrolysis uses an alternating current for the reason that it is possible to form a uniform and high-density recess, and the peak current density is 30 A / dm ² or more, the average current density is 13 A / dm ² or more, and The electrolytic treatment is preferably performed under the condition that the amount of electricity is 150 c / dm ² or more. The peak current density is preferably 100 A / dm ² or less, the average current density is preferably 40 A / dm ² or less, and the amount of electricity is preferably 400 c / dm ² or less.
In addition, the concentration and temperature of the electrolytic solution in nitric acid electrolysis are not particularly limited, and electrolysis is performed at a high concentration, for example, 30 to 60 ° C. using a nitric acid electrolytic solution having a nitric acid concentration of 15 to 35% by mass, or a nitric acid concentration of 0. Electrolysis can be carried out at a high temperature, for example, at 80 ° C. or higher, using a 7-2 mass% nitric acid electrolyte.

<Hydrochloric acid electrolysis>
In the present invention, a concave portion having an average opening diameter of 0.5 μm to 3.0 μm is formed by an electrochemical surface roughening treatment (hereinafter also referred to as “hydrochloric acid electrolysis”) using an electrolytic solution mainly composed of hydrochloric acid. It can be formed at a density of not less than 100 / μm ² .
Here, in hydrochloric acid electrolysis, for the reason that uniform and high-density recesses can be formed, an alternating current is used, the peak current density is 30 A / dm ² or more, the average current density is 13 A / dm ² or more, and The electrolytic treatment is preferably performed under the condition that the amount of electricity is 150 c / dm ² or more. The peak current density is preferably 100 A / dm ² or less, the average current density is preferably 40 A / dm ² or less, and the amount of electricity is preferably 400 c / dm ² or less.

[Metal coating process]
The method for producing an aluminum plate of the present invention is such that the average opening diameter of the through holes formed by the above-described electrolytic dissolution treatment can be adjusted to a small range of about 1 μm to 20 μm. It is preferable to have a metal coating step of coating a part or all of the surface of the aluminum base material including the inner wall of the hole with a metal other than aluminum.
Here, “at least part or all of the surface of the aluminum substrate including the inner wall of the through hole is coated with a metal other than aluminum” means that at least the entire surface of the aluminum substrate including the inner wall of the through hole is penetrated. This means that the inner wall of the hole is covered, and the surface other than the inner wall may not be covered, or may be partially or entirely covered.
Hereinafter, the metal coating step will be described with reference to FIG.

As described above, the aluminum plate 10 shown in FIG. 2 includes the first metal layer 6 and the second metal made of a metal or alloy other than aluminum on the front and back surfaces of the aluminum base 3 having through holes and the inner wall of the through holes. It is an aspect having the layer 7, and can be produced, for example, by subjecting the aluminum base material shown in FIG. 3D or FIG.

<Replacement process>
The replacement treatment is a treatment in which zinc or a zinc alloy is subjected to replacement plating on a part or all of the surface of the aluminum substrate including at least the inner wall of the through hole.
Examples of the displacement plating solution include a mixed solution of sodium hydroxide 120 g / l, zinc oxide 20 g / l, crystalline ferric chloride 2 g / l, lossel salt 50 g / l, and sodium nitrate 1 g / l.
Commercially available Zn or Zn alloy plating solution may also be used. For example, Substar Zn-1, Zn-2, Zn-3, Zn-8, Zn-10, Zn-111 manufactured by Okuno Pharmaceutical Co., Ltd. Zn-222, Zn-291, etc. can be used.
The immersion time of the aluminum substrate in such a displacement plating solution is preferably 15 seconds to 40 seconds, and the immersion temperature is preferably 15 seconds to 40 seconds.

<Plating treatment>
When the zinc film is formed by replacing the surface of the aluminum base material with zinc or a zinc alloy by the above-described replacement treatment, for example, the zinc film is replaced with nickel by electroless plating described later, and then described later. It is preferable to perform a plating treatment for depositing various metals by electrolytic plating.

(Electroless plating treatment)
As the nickel plating solution used for the electroless plating treatment, commercially available products can be widely used. Examples thereof include an aqueous solution containing 30 g / l nickel sulfate, 20 g / l sodium hypophosphite, and 50 g / l ammonium citrate.
Examples of the nickel alloy plating solution include a Ni—P alloy plating solution in which a phosphorus compound is a reducing agent and a Ni—B plating solution in which a boron compound is a reducing agent.
The immersion time in such a nickel plating solution or nickel alloy plating solution is preferably 15 seconds to 10 minutes, and the immersion temperature is preferably 30 ° C. to 90 ° C.

(Electrolytic plating treatment)
As the electroplating treatment, for example, a plating solution for electroplating Cu includes, for example, Cu 60 to 110 g / L, sulfuric acid 160 to 200 g / L and hydrochloric acid 0.1 to 0.15 mL / L to pure water. Furthermore, plating solutions containing Top Lucina SF Base WR 1z 5 to 5.0 mL / L, Top Lucina SF-B 0.5 to 2.0 mL / L, and Top Lucina SF Leveler 3.0 to 10 mL / L as additives are also listed. It is done.
The immersion time in such a copper plating solution is not particularly limited because it depends on the thickness of the Cu film, but for example, when a 2 μm Cu film is applied, it is preferable to immerse for about 5 minutes at a current density of 2 A / dm, The immersion temperature is preferably 20 ° C. to 30 ° C.

[Boehmite treatment]
In the method for producing an aluminum plate of the present invention, the average opening diameter of the through holes formed by the above-described electrolytic dissolution treatment can be adjusted to a small value in the range of about 1 to 20 μm. It is preferable to perform anodizing treatment after forming an oxide film and then performing boehmite treatment.
Here, the boehmite treatment uses a reaction in which aluminum reacts with high-temperature water or superheated steam to form a pseudo-boehmite hydrated oxide film. For example, water at 100 to 400 ° C. (for example, pure water) Water, deionized water) can be adjusted to pH 7-12 and a hydrated oxide film can be formed by immersing the aluminum substrate.

[Washing treatment]
In the present invention, it is preferable to carry out water washing after completion of the above-described processes. For washing, pure water, well water, tap water, or the like can be used. A nip device may be used to prevent the processing liquid from being brought into the next process.

Hereinafter, the present invention will be described in more detail based on examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

[Example 1]
<Preparation of current collector aluminum substrate>
The surface of an aluminum base material (JIS H-4160, alloy number: 1N30-H, aluminum purity: 99.30%) having an average thickness of 20 μm and a width of 200 mm is subjected to the following treatment to obtain an aluminum base material for a current collector Was made.

(A1) Oxide film formation process (oxide film formation process)
A solution having a sulfuric acid concentration of 170 g / L and an aluminum concentration of 5% or less was applied to the aluminum substrate, and the aluminum substrate was used as an anode, and a DC current density of 5 A / dm ² and a DC voltage of 3 V were applied for 27 seconds at 52 ° C. Then, an oxide film (film amount: 0.6 g / m ² ) was formed on one surface (one surface) of the aluminum substrate. Then, water washing by spraying was performed.

(B1) Electrolytic dissolution treatment (through hole forming step)
Next, using an electrolytic solution (nitric acid concentration: 1%, aluminum concentration: 4.5 g / L) kept at 50 ° C., the electrolytic treatment is performed under the condition that the total amount of electricity is 1500 C / dm ² with the aluminum base material as the anode. And through holes were formed in the aluminum substrate and the oxide film. The electrolytic treatment was performed with a DC power wave. Current density was 10A / dm ^2.
Then, it was washed with water by spraying and dried.

(C1) Oxide film removal process (oxide film removal step)
Next, the aluminum substrate after electrolytic dissolution treatment is immersed in an aqueous solution (liquid temperature: 35 ° C.) having a caustic soda concentration of 5 mass% and an aluminum ion concentration of 0.5 mass% for 3 seconds to dissolve the oxide film, Removed.
Then, the aluminum plate which has a through-hole was produced by performing water washing by spraying and making it dry.

[Example 2]
Using an aluminum base material (JIS H-4160, alloy number: 8021-H, aluminum purity: 98.10%) having an average thickness of 12 μm and a width of 200 mm as the aluminum base material, the oxide film shown in (a1) above is formed. Example 1 except that the oxide film forming process shown in the following (a2) was performed instead of the process, and the electrolytic dissolving process shown in the following (b2) was performed instead of the electrolytic dissolving process shown in the above (b1). An aluminum plate was produced in the same manner.

(A2) Oxide film formation process (oxide film formation process)
A solution having a sulfuric acid concentration of 170 g / L and an aluminum concentration of 5% or less was applied to the aluminum substrate, and the aluminum substrate was used as an anode, and a DC current density of 25 A / dm ² and a DC voltage of 15 V were applied for 16 seconds at 52 ° C. Then, an oxide film (film amount: 2.4 g / m ² ) was formed on one surface (one surface) of the aluminum base material. Then, water washing by spraying was performed.

(B2) Electrolytic dissolution treatment (through-hole forming step)
Next, using an electrolytic solution (nitric acid concentration: 1%, aluminum concentration: 4.5 g / L) kept at 50 ° C., electrolytic treatment is performed under the condition that the total amount of electricity is 500 C / dm ² with the aluminum base material as the anode. And through holes were formed in the aluminum substrate and the oxide film. The electrolytic treatment was performed with a DC power wave. Current density was 10A / dm ^2. Then, it was washed with water by spraying and dried.

Example 3
Instead of the oxide film forming process shown in the above (a1), the oxide film forming process shown in the above (a2) is performed, and instead of the electrolytic dissolving process shown in the above (b1), the electrolytic dissolving process shown in the following (b3) is performed. An aluminum plate was produced in the same manner as in Example 1 except that it was applied.

(B3) Electrolytic dissolution treatment (through-hole forming step)
Next, using an electrolytic solution kept at 50 ° C. (nitric acid concentration: 1%, aluminum concentration: 4.5 g / L), an aluminum substrate is used as an anode, and an electrolytic treatment is performed under a condition where the total amount of electricity is 1000 C / dm ^2. And through holes were formed in the aluminum substrate and the oxide film. The electrolytic treatment was performed with a DC power wave. Current density was 10A / dm ^2. Then, it was washed with water by spraying and dried.

Example 4
An aluminum plate was produced in the same manner as in Example 3 except that the total amount of electricity in the electrolytic treatment in the electrolytic dissolution treatment shown in (b3) was 2000 C / dm ² .

Example 5
An aluminum plate was produced in the same manner as in Example 4 except that an aluminum substrate (A1085, aluminum purity: 99.85%) having an average thickness of 20 μm and a width of 200 mm was used as the aluminum substrate.

Example 6
An aluminum plate was prepared in the same manner as in Example 2 using an aluminum substrate (JIS H-4160, alloy number: 8021-H, aluminum purity: 98.10%) having an average thickness of 15 μm as the aluminum substrate.

Example 7
As the aluminum base material, an aluminum base material having an average thickness of 12 μm (JIS H-4160, alloy number: 8021-H, aluminum purity: 98.10%) was used, and the electrolytic dissolution treatment (through-hole formation) shown in (b2) above. An aluminum plate was produced in the same manner as in Example 2 except that the current density of the electric field treatment in the step) was 25 A / dm ² .

[Comparative Example 1]
Using a gravure roll, a resist film having a predetermined pattern is formed on both surfaces of an aluminum substrate (JIS H-4160, alloy number: 1N30-H, aluminum purity: 99.30%) having an average thickness of 20 μm and a width of 200 mm. Formed. The main component of the resist ink is an acrylic resin, and a small amount of pigment is blended. The viscosity of the resist ink was adjusted with toluene. Next, an etching process of ferric chloride was used to perform an etching process at a temperature of 40 ° C. for about 10 seconds, thereby forming through holes having a predetermined pattern in the aluminum foil. Thereafter, the resist ink was dissolved and removed with caustic soda to produce an aluminum plate.

[Comparative Example 2]
An aluminum plate was produced in the same manner as in Example 3 except that the total amount of electricity in the electrolytic treatment in the electrolytic dissolution treatment shown in (b3) was 3000 C / dm ² .

[Comparative Example 3]
An aluminum plate was produced in the same manner as in Example 3 except that an aluminum substrate (aluminum purity: 99.99%) having an average thickness of 20 μm and a width of 200 mm was used as the aluminum substrate.

The average opening diameter and average opening ratio of the through holes of the produced aluminum plate were measured by the following methods.
The average aperture diameter was obtained by photographing the surface of an aluminum plate at a magnification of 200 times from directly above using a high-resolution scanning electron microscope (SEM). Twenty samples were extracted, and the diameter was read as the opening diameter, and the average value of these was calculated as the average opening diameter.
Further, the average aperture ratio of the through-holes was obtained by photographing the surface of the aluminum plate at a magnification of 200 times from directly above using a high resolution scanning electron microscope (SEM), and a 30 mm × 30 mm visual field (5 ), Binarize with image analysis software, etc., and observe the through-hole part and the non-through-hole part. From the total of the opening area of the through-hole and the area of the visual field (geometric area), Calculated from the geometric area), and the average value in each field of view (5 locations) was calculated as the average aperture ratio.

[Evaluation]
<Applicability>
An active material layer was formed on both surfaces of the produced aluminum plate, and the applicability was evaluated by the presence or absence of irregularities on the surface of the active material layer.
First, as an active material, 100 parts by mass of an activated carbon powder having a specific surface area of 1950 m ² / g, 10 parts by mass of acetylene black, 7 parts by mass of an acrylic binder, and 4 parts by mass of carboxymethylcellulose are added to water and dispersed. By doing this, the slurry was adjusted.
Next, the prepared slurry was applied to both surfaces of the aluminum plate on which the through holes were formed by a die coater so as to have a total thickness of 200 μm, thereby forming an active material layer on the surface of the aluminum plate.
The surface of the formed active material layer is visually evaluated to see if there are irregularities, A is when there are no irregularities with a diameter of 40 μm or more, B is when irregularities with a diameter of 40 to 100 μm are seen, and irregularities with a diameter of 100 μm or more are seen. The case where it was made was designated as C.

<Tensile strength>
The tensile strength of the produced aluminum plate was measured by a tensile test according to JIS Z2241 (tensile speed: 2 mm / min).
The evaluation results are shown in Table 1.

As shown in Table 1, from the comparison between Examples and Comparative Examples, the average thickness is 50 μm or less, the purity of aluminum is 85% to 99.90%, the average opening diameter of the through holes is 1 μm to 100 μm, and the average opening ratio It can be seen that by setting the content to 1% to 40%, the coating property of the active material layer is improved, the surface uniformity is improved, and the tensile strength can be increased.
Further, from comparison between Example 3 and Example 4, it can be seen that the average aperture diameter is more preferably 40 μm or less and the average aperture ratio is more preferably 20% or less.
Further, from the comparison of Example 4, Example 5 and Example 6, it can be seen that the purity of aluminum is more preferably 99.80% or less, and more preferably less than 98.5%.
From the above, the effects of the present invention are clear.

DESCRIPTION OF SYMBOLS 1 Aluminum base material 2 Oxide film 3 Aluminum base material which has through-hole 4 Oxide film which has through-hole 5 Through-hole 6 1st metal layer 7 2nd metal layer 10 Aluminum plate 30 Electrode 32 Active material layer

Claims

In an aluminum plate having a plurality of through holes in the thickness direction,
The average thickness is 50 μm or less, the purity of aluminum is 85% to 99.90%,
An aluminum plate, wherein the through holes have an average opening diameter of 1 μm to 100 μm and an average opening ratio of 1% to 40%.
The aluminum plate according to claim 1, wherein the purity of the aluminum is 90% to 99.80%.
The aluminum plate according to claim 1 or 2, wherein an average opening diameter of the through holes is 1 µm to 60 µm.
4. The aluminum plate according to claim 1, wherein an average opening ratio of the through holes is 5% to 30%.
The aluminum plate according to any one of claims 1 to 4, further comprising a metal layer made of metal plating covering at least the inner surface of the through hole.