WO2022044624A1 - Aluminum member for collectors, lithium ion capacitor, electric double layer capacitor, semi-solid battery, solid-state battery and secondary battery using nonaqueous electrolyte solution - Google Patents

Abstract

The present invention addresses the problem of providing: an aluminum member for collectors, said aluminum member exhibiting high adhesion to an electrode material, while having low contact resistance with respect to the electrode material; a lithium ion capacitor; an electric double layer capacitor; a semi-solid battery; a solid-state battery; and a secondary battery which uses a nonaqueous electrolyte solution. An aluminum member for collectors, said aluminum member comprising an aluminum substrate and an anodic oxide coating on the aluminum substrate. With respect to this aluminum member for collectors, the anodic oxide coating has a plurality of micropores; the anodic oxide coating is present on the aluminum substrate in the form of an island; the coverage of the aluminum substrate surface by the anodic oxide coating is from 1% to 80%; and the number density of the micropores in the anodic oxide coating is 600/μm² or more.

Description

Aluminum members for collectors, as well as secondary batteries that use lithium ion capacitors, electric double layer capacitors, semi-solid-state batteries, solid-state batteries, and non-aqueous electrolytes.

The present invention comprises an aluminum member for a current collector, a lithium ion capacitor having the aluminum member for the current collector, an electric double layer capacitor, a semi-solid battery, a solid battery, and a secondary battery using a non-aqueous electrolyte solution. Regarding.

In recent years, with the development of portable devices such as personal computers and mobile phones, hybrid vehicles, and electric vehicles, storage devices as power sources thereof, particularly lithium ion capacitors, lithium ion secondary batteries, and electric double layer capacitors. The demand for such equipment is increasing.

It is known that an aluminum plate can be used as an electrode current collector (hereinafter, simply referred to as "current collector") used for a positive electrode and / or a negative electrode of such a power storage device. It is also known that an active material, activated carbon, or the like can be coated on the surface of a current collector made of an aluminum plate as an electrode material and used as an electrode for a positive electrode or a negative electrode.

For example, Patent Document 1 is a method for manufacturing an aluminum plate having an aluminum base material having a plurality of through holes in the thickness direction, wherein an oxide film forming treatment is applied to the surface of the aluminum base material having a thickness of 5 to 1000 μm. A method for producing an aluminum plate is described, which comprises an oxide film forming step of forming an oxide film and a through hole forming step of subjecting an electrochemical dissolution treatment to form a through hole after the oxide film forming step.

Patent Document 2 describes in an aluminum plate having a plurality of through holes penetrating in the thickness direction.
An aluminum plate having an average opening diameter of 1 μm to 100 μm, a density of through holes of 50 pieces / mm ² to 2000 pieces / mm ² , and a distance between adjacent through holes of 300 μm or less is described. ing.

Patent Document 3 describes a collector film of a lithium ion secondary battery in which pits having an average pit diameter in the range of 0.05 to 0.10 μm are formed on the surface having an average density of 100 to 500 pieces / μm ² . Aluminum foil is listed.

Patent Document 4 describes an aluminum foil for a current collector of a lithium ion battery in which a barrier-type anodic oxide film having a thickness of 5 to 1000 nm is formed on the surface.

International Publication No. 2015/115531 International Publication No. 2016/05/1976 Japanese Unexamined Patent Publication No. 2000-113892 Japanese Unexamined Patent Publication No. 2007-250376

It is desirable that the current collector has high adhesion to the electrode material and has low contact resistance with the electrode material. In order to improve the adhesion to the electrode material, Patent Documents 1 to 3 describe roughening the aluminum plate. However, it has been difficult to achieve both a sufficient adhesion effect and a reduction in contact resistance. In addition, a sufficient effect on the cost of the roughening treatment was not obtained, and it was rarely put into practical use.

Further, Patent Document 4 describes that the adhesion is improved by forming an anodic oxide film having fine pores on the surface of the aluminum foil. However, since the anodic oxide film is inferior in conductivity, there is a problem that the contact resistance with the electrode material increases when the anodic oxide film is provided on the surface.

Therefore, the present invention relates to an aluminum member for a current collector having high adhesion to the electrode material and low contact resistance to the electrode material, as well as a lithium ion capacitor, an electric double layer capacitor, a semi-solid battery, and a solid battery. Another object of the present invention is to provide a secondary battery using a non-aqueous electrolyte solution.

The present invention solves the problem by the following configuration.

[1] An aluminum member for a current collector having an aluminum base material and an anodic oxide film on the aluminum base material.
The anodic oxide film has a large number of micropores and has a large number of micropores.
The coverage of the anodic oxide film on at least one surface of the aluminum substrate is 1-80%.
An aluminum member for a current collector having a number density of 600 micropores / μm ² or more in the anodic oxide film.
[2] The aluminum member for a current collector according to [1], wherein the anodic oxide film exists in an island shape on an aluminum base material.
[3] The aluminum member for a current collector according to [1] or [2], wherein the average diameter of the micropores is 1 nm to 100 nm.
[4] The aluminum member for a current collector according to any one of [1] to [3], wherein the anodic oxide film has a thickness of 1 nm to 30 nm.
[5] The aluminum member for a current collector according to any one of [1] to [4], wherein the aluminum base material has a granular intermetallic compound on the surface.
[6] The aluminum member for a current collector according to [5], wherein the surface of the aluminum base material has 500 pieces / mm ² or more of granular intermetallic compounds.
[7] The aluminum member for a current collector according to any one of [1] to [6], wherein the thickness of the aluminum base material is 5 μm to 100 μm.
[8] The aluminum member for a current collector according to any one of [1] to [7], wherein the aluminum member for the current collector is plate-shaped.
[9] The lithium ion capacitor having the aluminum member for a current collector according to any one of [1] to [8].
[10] The electric double layer capacitor having the aluminum member for a current collector according to any one of [1] to [8].
[11] A semi-solid-state battery having the aluminum member for a current collector according to any one of [1] to [8].
[12] A solid-state battery having the aluminum member for a current collector according to any one of [1] to [8].
[13] A secondary battery using a non-aqueous electrolytic solution having the aluminum member for a current collector according to any one of [1] to [8].

According to the present invention, an aluminum member for a collector having high adhesion to an electrode material and a small contact resistance with the electrode material, a lithium ion capacitor, an electric double layer capacitor, a semi-solid battery, a solid battery, and the like. And a secondary battery using a non-aqueous electrolyte can be provided.

It is sectional drawing which shows typically an example of the aluminum member for a current collector of this invention. It is a top view of the aluminum member for a current collector shown in FIG. 1. It is sectional drawing which shows typically another example of the aluminum member for a current collector of this invention. It is a schematic sectional drawing for demonstrating an example of the preferable manufacturing method of the aluminum member for a current collector of this invention. It is a schematic sectional drawing for demonstrating an example of the preferable manufacturing method of the aluminum member for a current collector of this invention. It is a schematic sectional drawing for demonstrating an example of the preferable manufacturing method of the aluminum member for a current collector of this invention. It is a schematic sectional drawing for demonstrating another example of the preferable manufacturing method of the aluminum member for a current collector of this invention. It is a schematic sectional drawing for demonstrating another example of the preferable manufacturing method of the aluminum member for a current collector of this invention. It is a conceptual diagram for demonstrating an example of the manufacturing apparatus which carries out the preferable manufacturing method of the aluminum member for a current collector of this invention. It is an SEM image of the aluminum member for a current collector of an Example. It is a partially enlarged view of the SEM image of the aluminum member for a current collector of an Example. It is a partially enlarged view of the SEM image of the aluminum member for a current collector of a comparative example. It is a figure which shows typically the measuring apparatus which performs the measurement of the peel strength. It is a figure which shows typically the apparatus which performs the resistance measurement.

Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be based on the representative embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present specification, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.

[Aluminum member for current collector]
The aluminum member for a current collector of the present invention is
An aluminum member for a current collector having an aluminum substrate and an anodic oxide film on the aluminum substrate.
The anodic oxide film has a large number of micropores and has a large number of micropores.
The coverage of the anodic oxide film on at least one surface of the aluminum substrate is 1-80%.
It is an aluminum member for a current collector having a number density of 600 micropores / μm ² or more in the anodic oxide film.

The configuration of the aluminum member for a current collector of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a schematic cross-sectional view showing an example of a preferred embodiment of the aluminum member for a current collector of the present invention. FIG. 2 is a top view of the aluminum member for a current collector shown in FIG. Note that FIG. 2 is a diagram depicting contour lines between the aluminum base material and the anodic oxide film in an image obtained by observing the surface of the aluminum member for a current collector in an embodiment described later with a scanning electron microscope (SEM). ..
As shown in FIGS. 1 and 2, the current collector aluminum member 10 has an island-shaped anodic oxide film (hereinafter, also referred to as an island-shaped anodic oxide film) 14 existing on both main surfaces of the aluminum base material 1. Is formed. The main surface is the maximum surface of a plate-shaped (sheet-shaped) member.

The island-shaped anodized film 14 is an aluminum oxide film containing an aluminum oxide such as aluminum oxide (Al ₂ O ₃ ) formed by anodizing treatment.

In the present invention, the island-shaped anodized film 14 has a large number of micropores (pores) as shown in the SEM (scanning electron microscope) image of the example shown in FIG. 11 described later. The number density of these micropores is 600 / μm ² or more. Further, the anodic oxide film 14 exists in an island shape on the aluminum base material 1. Here, "island-like" means not a uniform layer but an irregular structure divided into innumerable pieces as shown in FIG. When the coverage of the anodic oxide film is high, the portion without the anodic oxide film is innumerably divided into an amorphous structure. The coverage of the island-shaped anodic oxide film 14 on the surface of the aluminum base material 1 is 1 to 80%.

The aluminum member for a current collector of the present invention is used as a current collector, and an active material (electrode material) is coated on the surface thereof to be used as a positive electrode or a negative electrode of a power storage device.

As described above, it is desired that the current collector has high adhesion to the electrode material and low contact resistance with the electrode material. However, in order to improve the adhesion to the electrode material, even if the surface of the aluminum base material is roughened, a sufficient adhesion effect cannot be obtained, and both adhesion and low resistance cannot be achieved at the same time.
Further, it has been proposed to improve the adhesion by forming an anodic oxide film having fine pores on the surface of the aluminum base material. However, since the anodic oxide film has poor conductivity, anodic oxidation is performed on the surface. Having a film increases the contact resistance with the electrode material, making it impossible to achieve both adhesion and low resistance.

On the other hand, the aluminum member for a current collector of the present invention has an anodic oxide film 14 in an island shape on the aluminum base material 1. In the portion where the aluminum base material 1 is covered with the anodic oxide film 14 having micropores having a number density of 600 pieces / μm ² or more, the adhesion to the electrode material can be improved. On the other hand, in the portion where the aluminum base material 1 is not covered with the anodic oxide film 14, the contact resistance with the electrode material can be reduced. By setting the coverage of the island-shaped anodic oxide film 14 on the surface of the aluminum base material 1 to 1 to 80%, it is possible to achieve both adhesion to the electrode material and low resistance.

Here, from the viewpoint of achieving both adhesion to the electrode material and low resistance, the coverage of the surface of the aluminum base material 1 by the island-shaped anodic oxide film 14 is preferably 1 to 65%, preferably 3 to 50%. More preferably, 3 to 30% is even more preferable.

The coverage of the island-shaped anodic oxide film 14 on the surface of the aluminum base material 1 is measured as follows.
The surface of the aluminum member for the current collector is photographed at 10000 times using SEM, the anodic oxide film portion and the aluminum base material portion are binarized with image analysis software, and the area ratio of the anodic oxide film is obtained. General image analysis software can be used, for example, ImageJ, image factory, etc. can be used. FIG. 2 to be described later is an SEM photograph of the aluminum member for a current collector produced in the examples, and FIG. 2 is a contour diagram obtained by using ImageJ.

When the current collector aluminum member has through holes, the area ratio of the anodic oxide film on the surface of the aluminum base material excluding the through holes is used as the coverage ratio.

Further, from the viewpoint of adhesion to the electrode material, the number density of the micropores of the anodic oxide film 14 is preferably 600 to 1100 / μm ² , more preferably 800 to 1100 / μm ² , and 900 to 1100 / μm 2. μm ² is more preferred.

Further, from the viewpoint of adhesion to the electrode material, the average diameter of the fine pores of the anodic oxide film 14 is preferably 1 nm to 100 nm, more preferably 10 nm to 30 nm, and even more preferably 20 nm to 30 nm.

The number density and average diameter of the fine pores of the anodic oxide film 14 are measured as follows.
The presence or absence of micropores can be determined by photographing the surface of the aluminum member for a current collector at a magnification of 50,000 using an SEM. If there are micropores, measure how many micropores are in the area of the anodized film with image analysis software, and measure the number of micropores per unit area of the anodized film, that is, per 1 μm ² of the area of the anodized film. The number of micropores can be obtained. Further, the average diameter can be obtained by measuring the diameters of the micropores existing in the area of the anodic oxide film and averaging them.

Further, from the viewpoint of reducing the contact resistance with the electrode material, the thickness of the anodic oxide film 14 is preferably 1 nm to 30 nm, more preferably 5 nm to 30 nm, and even more preferably 10 nm to 30 nm.

The thickness of the anodic oxide film 14 is measured as follows.
From the boundary between the anodic oxide film part and the aluminum base material part in the photograph of the surface of the aluminum member for the current collector taken at 50,000 times using a sample table that can be attached by tilting the observation sample by 75 degrees with SEM. The thickness of the anodic oxide film can be determined.

Here, in the example shown in FIG. 1, the anodic oxide film 14 is configured to be formed on both main surfaces of the aluminum base material 1, but is not limited to this, and is formed only on one main surface. It may be configured.

Further, in the aluminum member for a current collector of the present invention, the portion of the aluminum base material that is not covered with the anodic oxide film may be covered with the natural oxide film. The natural oxide film has a smaller contact resistance with the electrode material than the anodic oxide film. Therefore, even if the portion of the aluminum base material that is not covered with the anodic oxide film is covered with the natural oxide film, it is possible to achieve both adhesion to the electrode material and low resistance.
The natural oxide film basically does not have a large number of micropores. Therefore, by observing the presence or absence of micropores using SEM, it is possible to determine whether it is an anodic oxide film or a natural oxide film.

Further, from the viewpoint of reducing the contact resistance with the electrode material, the thickness of the natural oxide film is preferably 10 nm or less, more preferably 1 nm to 5 nm, still more preferably 1 nm to 3 nm.

The aluminum member for a current collector of the present invention may have a through hole.
FIG. 3 shows a cross-sectional view schematically showing another example of the aluminum member for a current collector of the present invention.
In the aluminum member 10b for a current collector shown in FIG. 3, an anodic oxide film 14 existing in an island shape is formed on both main surfaces of an aluminum base material 3 having a through hole 5.

The through hole 5 is a through hole that penetrates the aluminum base material 3 and the anodic oxide film 14 in the thickness direction.

Since the aluminum member for the current collector has a plurality of through holes penetrating in the thickness direction, it is possible to facilitate the movement of lithium ions when used as a current collector. Further, by having a large number of through holes, it is possible to improve the adhesion with the active material.

The average opening diameter of the through hole is preferably 0.1 μm or more and less than 100 μm, more preferably more than 1 μm and 80 μm or less, further preferably more than 3 μm and 40 μm or less, and particularly preferably 5 μm or more and 30 μm or less.
By setting the average opening diameter of the through hole to the above range, it is possible to prevent the active material from coming off when the active material or the like is applied to the aluminum member for the current collector, and the adhesion with the applied active material can be improved. Can be improved. Further, even when the current collector aluminum member has a large number of through holes, it can have sufficient tensile strength.

The average opening diameter of the through hole is measured as follows.
Parallel light is irradiated from one surface of the aluminum member for the current collector, and the through hole is photographed with a transmission type optical microscope at a magnification of 200 times. The obtained data is binarized with image analysis software, and the average value of the circle-equivalent diameters of the through holes is defined as the average opening diameter.

The average aperture ratio of the through holes is preferably 0.5% to 30%, more preferably 1% to 30%, further preferably 2% to 20%, and particularly preferably 3% to 10%.
By setting the average aperture ratio of the through holes to the above range, it is possible to prevent the active material from coming off when the active material is applied to the aluminum member for the current collector, and the adhesion with the applied active material is improved. can. Further, even when the current collector aluminum member has a large number of through holes, it can have sufficient tensile strength.

The average aperture ratio of the through hole is measured as follows.
Parallel light is irradiated from one surface of the aluminum member for the current collector, and the through hole is photographed with a transmission type optical microscope at a magnification of 200 times. The obtained data is binarized by image analysis software and calculated as the total opening area / observation area × 100 (%).

Further, the surface of the current collector aluminum member may be roughened. By having a rough surface, the surface area of both the aluminum base material and the anodic oxide film portion is increased, and the area in contact with the active material layer is increased, so that the adhesion is further improved.

Here, in the present invention, it is preferable that the aluminum base material has a large number of granular intermetallic compounds dispersed in the film on its surface. In the following description, the granular intermetallic compound is also simply referred to as "intermetallic compound".
The anodic oxide film has higher insulating properties than the aluminum base material. In addition, although the natural oxide film has a lower insulating property than the anodized film, it has a higher resistance than the aluminum metal alone. In the following description, the anodic oxide film and the natural oxide film are collectively referred to as an oxide film. On the other hand, when the aluminum base material has an intermetallic compound, the oxide film formed on the surface thereof also contains the intermetallic compound. It was found that the intermetallic compound serves as a starting point for reducing the insulating property in the oxide film. By having an intermetallic compound that serves as a starting point for lowering the insulating property, the insulating property of the oxide film can be lowered and the contact resistance of the oxide film can be lowered.

The intermetallic compound of the oxide film preferably has an oxygen element ratio O / Al to aluminum of 2 or more and 4 or less. Further, the number density of the granular intermetallic compound is preferably 500 pieces / mm ² or more.

Here, the intermetallic compound in the present invention is a compound containing an aluminum element (Al) and at least one selected from Fe, Si, Mn, Mg, Ti, B and the like. Specifically, examples of the intermetallic compound include Al ₃ Fe, Al ₆ Fe, αAlFeSi, AlFeMnSi, Mg ₂ Si, and TiB ₂ . Of these, the intermetallic compound containing Al contains Al, so that an aluminum oxide film is formed on the surface. Therefore, the surface layer of the intermetallic compound containing Al contains an oxygen element (O).

In the aluminum member for a current collector of the present invention, the oxide film on the surface of the metal-to-metal compound contains 500 pieces / mm ² or more of granular intermetal compounds having an oxide film having an element ratio O / Al of 2 or more and 4 or less. The oxide film on the outermost layer may have a granular intermetal compound having an element ratio O / Al of 2 or more and 4 or less. That is, the oxide film on the outermost layer may have a granular intermetallic compound having an element ratio O / Al of less than 2 or more than 4.

When the oxide film contains aluminum oxide (Al ₂ O ₃ ) as a main component and does not contain hydrate, the element ratio O / Al in the portion of the oxide film other than the intermetallic compound is less than 2. It is about 3 to 1.5.

From the viewpoint of lowering the electrical resistance of the aluminum member for the current collector, the average value of the element ratio O / Al of the oxide film on the surface layer of the intermetallic compound is preferably 2 or more and 4 or less, preferably 2.5. It is more preferably 3.5 or less.

The element ratio O / Al of the outermost layer of the intermetallic compound is measured as follows.
When the surface of the oxide film is observed with a high-resolution scanning electron microscope (SEM), the intermetallic compound can be visually recognized separately from the portion of the oxide film other than the intermetallic compound.
Therefore, first, the surface of the oxide film is photographed at a magnification of 5000 times using a high-resolution scanning electron microscope (SEM), and at least 20 intermetallic compounds are extracted from the obtained SEM photograph.
Next, elemental analysis is performed at the position of the extracted intermetallic compound in the depth direction from the outermost surface using field emission Auger electron spectroscopy (FE-AES). Analysis in the depth direction is performed by repeating measurement and surface removal by sputtering. From the result of the element distribution in the depth direction by FE-AES, the element ratio O / Al in the outermost layer is obtained.

From the viewpoint of lowering the electrical resistance of the aluminum member for the current collector, the density of the granular intermetallic compound is preferably 1000 / mm ² to 300,000 / mm ² , and is preferably 5000 / mm ² to 200,000 / mm. mm ² is more preferred.

The density of the granular intermetallic compound is measured as follows.
First, the surface of the aluminum member for a current collector was photographed from directly above at a magnification of 5000 times using a high-resolution scanning electron microscope (SEM), and the obtained SEM photograph had a field of view (5) of 1.2 mm × 1.2 mm. For the location), granular intermetallic compounds are extracted.
Next, the elemental ratio O / Al of each intermetallic compound extracted by elemental analysis using FE-AES is determined. Count the number of granular intermetallic compounds with an element ratio O / Al of 2 or more and 4 or less, and calculate the number density from the number of granular intermetallic compounds in the visual field and the area of the visual field (geometric area). Then, the average value of the five visual fields is calculated as the density.

Here, it is preferable that the diameter equivalent to the circle of the granular intermetallic compound is 1 μm or less. An intermetallic compound having a diameter equivalent to a circle of 1 μm or less is easily exposed on the surface of an aluminum member for a current collector. When a small intermetallic compound appears on the surface of the aluminum member for a current collector, the surface area of the intermetallic compound with respect to the volume increases. As a result, it is considered that water molecules are easily adsorbed locally, and the element ratio O / Al of the oxidized intermetallic compound tends to be 2 or more.

The circle-equivalent diameter of the granular intermetallic compound is the area on the surface of the oxide film of the intermetallic compound by extracting at least 20 intermetallic compounds whose element ratio O / Al was measured as described above and using image analysis software or the like. Is obtained, the circle-equivalent diameter is obtained from this area, and the average value of these is calculated as the circle-equivalent diameter.

The oxide film on the outermost layer preferably contains 70% by mass or more of aluminum oxide (Al ₂ O ₃ ), more preferably 80% by mass to 100% by mass, and further preferably 90% by mass to 100% by mass. ..
By setting the content of the non-hydrated aluminum oxide (Al ₂ O ₃ ) in the oxide film to 70% by mass or more, the density of the oxide film can be increased, so that the oxide film becomes thicker with time. Can be suppressed. Therefore, it is preferable in that the oxide film becomes thick and the increase in electrical resistance can be suppressed.

The ratio of aluminum oxide (Al ₂ O ₃ ) in the oxide film can be calculated by measuring the film density of the oxide film as follows.
The film density of the oxide film is measured using a high resolution RBS analyzer HRBS500 (High Resolution Rutherford Backscattering Spectrometry; HR-RBS) manufactured by Kobe Steel, Ltd. He + ions with an energy of 450 keV are incident on the sample at 62.5 degrees with respect to the normal of the sample surface (the surface of the oxide film of the aluminum member for electrodes), and the scattered He + ions are deflected at a position of a scattering angle of 55 degrees. The surface density is obtained by detecting with an energy analyzer. The obtained surface density (atoms / cm ² ) is converted into mass surface density (g / cm ² ), and the density of the oxide film (g / cm ³ ) is calculated from this value and the film thickness measured by a transmission electron microscope (TEM). ) Is calculated.
The oxide film of aluminum consists of non-hydrated aluminum oxide and hydrated aluminum oxide (monohydrate and trihydrate exist), and the hydrate density is convenient because the hydrates have different densities. Therefore, the average of monohydrate and trihydrate is taken, and the weighted average of the density of non-hydrate is considered to be the density obtained above, and the ratio of non-hydrate aluminum oxide is obtained from it.

The shape of the aluminum member for the current collector is not particularly limited as long as it can be used as the current collector, but it is preferably plate-shaped.

<Aluminum base material>
The aluminum base material used as the base material of the aluminum member for the current collector is not particularly limited, and for example, known aluminum base materials such as alloy numbers 1N30, 3003, and 1085 described in JIS standard H4000 may be used. can. If aluminum containing a large amount of intermetallic compounds is used, the above-mentioned effect of reducing electrical resistance can be expected. However, the present application is not limited to the aluminum material. The aluminum base material is an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements.

[Manufacturing method of aluminum member for current collector]
Next, a method for manufacturing the aluminum member for a current collector of the present invention will be described.
An example of a method for manufacturing an aluminum member for a current collector for producing an aluminum member for a current collector of the present invention is as follows.
An electrolysis process that forms an anodic oxide film on the surface of an aluminum substrate,
A partial removal process that partially removes the anodic oxide film to form an island-like anodic oxide film,
It is a method of manufacturing an aluminum member for a current collector having.

Further, the method for manufacturing an aluminum member for a current collector may include a through hole forming step of forming a through hole penetrating the aluminum base material and the anodic oxide film.
Further, the method for manufacturing an aluminum member for a current collector may include a roughening step of roughening the surface of an aluminum base material.
The through hole forming step and / or the roughening step may be carried out at the same time as the electrolytic step of forming the anodic oxide film.

Further, after the partial removal step, it is preferable to carry out a washing and drying step of cleaning and drying the aluminum member for the current collector.

Further, it is preferable to have a water washing step of performing a water washing treatment and a drying step of performing a drying treatment after the completion of each step.

Hereinafter, each step of the method for manufacturing the aluminum member for a current collector will be described in FIGS. 4 to 4 by taking the aluminum member for the current collector shown in FIG. 1 and the aluminum member for a current collector having a through hole shown in FIG. 3 as an example. FIG. 8 will be used to explain each step of the method for manufacturing the aluminum member for a current collector, and then each step will be described in detail.

4 to 6 are schematic cross-sectional views showing an example of a preferred embodiment of the method for manufacturing an aluminum member for a current collector shown in FIG. 1.
As an example of a method for manufacturing an aluminum member for a current collector, as shown in FIGS. 4 to 6, both main surfaces of the aluminum base material 1 are subjected to electrolytic treatment to form a uniform anodic oxide film 2. A manufacturing method comprising an electrolysis step (FIGS. 4 and 5) and a partial removal step (FIGS. 5 and 6) in which the anodic oxide film is partially removed after the electrolysis step to form an island-shaped anodic oxide film 14. be.

4 to 5 and 7 to 8 are schematic cross-sectional views showing an example of a preferred embodiment of the method for manufacturing an aluminum member for a current collector shown in FIG.
As an example of a method for manufacturing an aluminum member for a current collector, as shown in FIGS. 4 to 5 and 7 to 8, both main surfaces of the aluminum base material 1 are electrolyzed and a uniform anode is applied. An electrolytic step of forming the oxide film 2 (FIGS. 4 and 5), a through hole forming step of forming a through hole penetrating the anodic oxide film 2 and the aluminum substrate 1 (FIGS. 5 and 7), and an anodic oxide film. Is a manufacturing method comprising a partial removal step (FIGS. 7 and 8) of partially removing the above to form an island-shaped anodic oxide film 14.

[Electrolysis process]
The electrolysis step is a step of forming a uniform anodic oxide film on the surface of the aluminum base material.
In the present invention, in order to form an anodized film having a number density of 600 micropores / μm ² or more in the anodized film, anodizing treatment can be performed using an aqueous solution containing nitric acid and sulfuric acid. preferable.

As a treatment method for anodizing, the same treatment as the conventionally known anodizing treatment can be performed except that an aqueous solution containing nitric acid and sulfuric acid is used. As the anodizing treatment, for example, the conditions and devices described in paragraphs [0063] to [0073] of JP2012-216513A can be appropriately adopted.

In the present invention, the conditions of the anodizing treatment cannot be unconditionally determined because they vary depending on the electrolytic solution used, but generally, the electrolytic solution concentration is 0.2 to 80% by mass and the liquid temperature is 5 to 70. It is appropriate that the temperature, 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, and the amount of the oxide film is adjusted to be desired.

Further, in the anodizing treatment, a direct current may be applied between the aluminum base material and the counter electrode, or an alternating current may be applied. When direct current is applied to the aluminum substrate, the current density is preferably 0.5 to 60 A / dm ² , and more preferably 1 to 40 A / dm ² . When the anodizing treatment is continuously performed, it is preferable to use a liquid feeding method in which the aluminum base material is fed via an electrolytic solution.

[Through hole forming process]
The through hole forming step is a step of forming a through hole in the aluminum base material.
The method for forming the through hole in the through hole forming step is not particularly limited, and a mechanical method such as punching or an electrochemical method such as electrolytic dissolution treatment can be used. A method for forming a through hole by electrolytic dissolution treatment is suitable because a through hole having an average opening diameter of 0.1 μm or more and less than 100 μm can be easily formed.
Further, the formation of the through holes by the electrolytic dissolution treatment can be carried out simultaneously or sequentially with the anodizing treatment in the above electrolytic step.

<Electrolytic dissolution treatment>
The electrolytic dissolution treatment is not particularly limited, and a direct current or an alternating current can be used, and an acidic solution can be used as the electrolytic solution. Among them, it is preferable to use an electrolytic solution mainly composed of nitric acid, and it is more preferable to carry out the electrochemical treatment using a mixed acid of at least one of sulfuric acid, phosphoric acid and oxalic acid in addition to these acids.

In the present invention, as the acidic solution which is an electrolytic solution, in addition to the above acids, US Pat. Nos. 4,671,859, 4,661,219, 4,618,405, and No. 4 4,600,482, 4,566,960, 4,566,958, 4,566,959, 4,416,972, 4,374,710 No. 4,336,113, No. 4,184,932, and the like described in each specification can also be used.

The concentration of the acidic solution is preferably 0.1 to 2.5% by mass, and particularly preferably 0.2 to 2.0% by mass. The temperature of the acidic solution is preferably 20 to 80 ° C, more preferably 30 to 60 ° C.

The acid-based aqueous solution is a nitrate compound having nitrate ions such as aluminum nitrate, sodium nitrate and ammonium nitrate or hydrochloric acid such as aluminum chloride, sodium chloride and ammonium chloride in an acid aqueous solution having a concentration of 1 to 100 g / L. At least one of a hydrochloric acid compound having an ion, an aluminum sulfate, sodium sulfate, ammonium sulfate and the like and a sulfuric acid compound having a sulfate ion can be added and used in the range from 1 g / L to saturation.
Further, the metal contained in the aluminum alloy such as iron, copper, manganese, nickel, titanium, magnesium and silica may be dissolved in the aqueous solution mainly containing an acid. It is preferable to use a solution obtained by adding aluminum chloride, aluminum nitrate, aluminum sulfate or the like to an aqueous solution having an acid concentration of 0.1 to 2% by mass so that aluminum ions are 1 to 100 g / L.

A DC current is mainly used for the electrochemical dissolution treatment, but when an AC current is used, the AC power wave is not particularly limited, and a sine wave, a square wave, a trapezoidal wave, a triangular wave, or the like is used. Of these, a square wave or a trapezoidal wave is preferable, and a trapezoidal wave is particularly preferable.

(Nitric acid electrolysis)
In the present invention, the average opening diameter is easily 0.1 μm or more and less than 100 μm by the electrochemical dissolution treatment (hereinafter, also abbreviated as “nitric acid dissolution treatment”) using an electrolytic solution mainly composed of nitric acid. Through holes having an average opening ratio of 0.5% to 30% can be formed.
Here, in the nitric acid dissolution treatment, a direct current is used, the average current density is 1 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 the through hole formation. It is preferable that the electrolytic treatment is performed in 1. The average current density is preferably 100 A / dm ² or less, and the amount of electricity is preferably 10000 C / dm ² or less.
Further, the concentration and temperature of the electrolytic solution in nitric acid electrolysis are not particularly limited, and electrolysis may be performed at a high concentration, for example, a nitric acid electrolytic solution having a nitric acid concentration of 15 to 35% by mass at 30 to 60 ° C., or the nitric acid concentration may be 0. Electrolysis can be performed at a high temperature, for example, 80 ° C. or higher, using a nitric acid electrolytic solution of 7 to 2% by mass.
Further, electrolysis can be performed using an electrolytic solution in which at least one of sulfuric acid, oxalic acid and phosphoric acid having a concentration of 0.1 to 50% by mass is mixed with the nitric acid electrolytic solution.

[Roughening process]
The roughening step is a step of subjecting an aluminum base material to an electrochemical roughening treatment (hereinafter, also abbreviated as "electrolytic roughening treatment") to roughen the front surface or the back surface of the aluminum base material. be.
By applying electrolytic roughening treatment to roughen the surface of the aluminum base material, the adhesion to the layer containing the active material is improved, and the contact area increases due to the increased surface area, so it is used for collectors. The capacity retention rate of the power storage device using the aluminum member is increased.
As the electrolytic roughening treatment, for example, the conditions and devices described in paragraphs [0041] to [0050] of JP2012-216513A can be appropriately adopted.

<Nitric acid electrolysis>
In the present invention, a recess having an average opening diameter of 0.5 μm to 100 μm can be easily formed in an area ratio by an electrochemical roughening treatment using an electrolytic solution mainly composed of nitric acid (hereinafter, also abbreviated as “nitric acid electrolysis”). It can be formed at 1% or more.
Here, the nitrate electrolysis uses an AC current to set the peak current density to 30 A / dm ² or more, the average current density to 13 A / dm ² or more, and the average current density to 13 A / dm 2 or more, because it enables the formation of uniform and dense recesses. It is preferable that the electrolytic treatment is 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.
Further, the concentration and temperature of the electrolytic solution in nitrate electrolysis are not particularly limited, and electrolysis may be performed at a high concentration, for example, a nitrate electrolytic solution having a nitrate concentration of 15 to 35% by mass at 30 to 60 ° C., or the nitrate concentration may be 0. Electrolysis can be performed at a high temperature, for example, 80 ° C. or higher, using 7 to 2% by mass of a nitrate electrolytic solution.

<Hydrochloric acid electrolysis>
In the present invention, even by electrochemical roughening treatment using an electrolytic solution mainly composed of hydrochloric acid (hereinafter, also abbreviated as “hydrochloric acid electrolysis”), recesses having an average opening diameter of 0.05 μm to 100 μm have an area ratio of 1. It can be formed in% or more.
Here, in hydrochloric acid electrolysis, an alternating current is used, the peak current density is set to 30 A / dm ² or more, the average current density is set to 13 A / dm ² or more, and the average current density is set to 13 A / dm 2 or more, because it is possible to form uniform and dense recesses. It is preferable that the electrolytic treatment is performed under the condition that the amount of electricity is 30 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.

[Partial removal process]
The partial removal step is a step of partially removing the anodizing film formed on the surface of the aluminum base material to increase the coverage of the anodized film to 1 to 80%.
The method for partially removing the anodic oxide film is not particularly limited, but a method for partially removing the anodic oxide film by a chemical dissolution treatment using an alkaline aqueous solution (hereinafter, also referred to as "alkali etching treatment"), an anodic oxide film is used. An example is a method of partially removing the anodic oxide film by passing the aluminum base material to be passed through a metal roll and then rubbing the surface with a brush roll (hereinafter, also referred to as “mechanical partial removal treatment”).

<Alkaline etching treatment>
The alkaline etching treatment is a treatment for partially removing the anodic oxide film by bringing the anodic oxide film into contact with an alkaline aqueous solution.
When the alkaline aqueous solution is brought into contact with the anodic oxide film, the alkaline aqueous solution permeates the anodic oxide film and dissolves the aluminum metal, whereby the anodic oxide film can be partially peeled off. In addition, the anodic oxide film itself can be dissolved. As a result, an island-shaped anodic oxide film is formed. In addition, the alkaline etching treatment can also enlarge the fine pores of the anodic oxide film.

Examples of the alkali used in the alkaline aqueous solution include caustic alkali and alkali metal salts. Specifically, examples of the caustic alkali include sodium hydroxide (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 alumin. Alkali metal aluminates such as potassium acid; alkali metal aldonates such as sodium gluconate, potassium gluconate; Examples include alkali metal hydrogen phosphate. Among them, a solution of caustic alkali and a solution containing both caustic alkali and alkali metal aluminate are preferable from the viewpoint of high etching rate and low cost. In particular, an aqueous solution of sodium hydroxide is preferable.

The concentration of the alkaline aqueous solution is preferably 0.1 to 50% by mass, more preferably 0.2 to 10% by mass. When the aluminum ion is dissolved in the alkaline aqueous solution, the concentration of the aluminum ion is preferably 0.01 to 10% by mass, 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 0.5 to 30 seconds.

As a method of bringing the anodic oxide film into contact with the alkaline solution, for example, a method of passing an aluminum base material having an anodic oxide film through a tank containing an alkaline solution, or a method of putting an aluminum base material having an anodic oxide film into an alkaline solution. Examples include a method of immersing in a tank and a method of spraying an alkaline solution on the surface of the anodic oxide film.

<Mechanical partial removal process>
The mechanical partial removal process is a process for mechanically partially removing the anodic oxide film.
Examples of the mechanical partial removal treatment include a method of pressing the anodic oxide film to generate a crack in the anodic oxide film and then partially removing the anodic oxide film starting from the crack.

Examples of the method of pressing the anodic oxide film include a method of passing an aluminum substrate having an anodic oxide film between roll pairs. At that time, a plurality of roll pairs may be passed. Further, as the roll pair, a metal roll is preferable.

Examples of a method for partially removing the cracked anodic oxide film include a method of rubbing the surface with a rotating brush roll.

[Washing and drying process]
The washing and drying step is a step of washing and drying the surface of the aluminum base material from which the anodic oxide film has been partially removed.
In the washing / drying step, it is preferable to perform washing in the order of water washing, pickling washing, and water washing. In addition, after cleaning is completed, a drying step is performed.

(Washing process)
Pure water, well water, tap water, or the like can be used for washing with water. A nip device may be used to prevent the treatment liquid from being brought into the next process.

(Pickling process)
Nitric acid, sulfuric acid and the like can be used for pickling. A nip device may be used to prevent the treatment liquid from being brought into the next process. Pickling with nitric acid or sulfuric acid is preferable because it tends to passivate the natural oxide film formed after pickling.

(Drying process)
The drying method is not limited, and known drying methods such as a method of blowing off water with an air knife and a method of heating can be appropriately used. Moreover, you may perform a plurality of drying methods.

FIG. 9 shows a schematic diagram of an example of a manufacturing apparatus that implements such a manufacturing method.
In the manufacturing apparatus 50 shown in FIG. 9, the aluminum base material 1 is sent out from the base material roll 70 formed by winding a long aluminum base material 1, and each step is carried out while transporting the aluminum base material 1 in the longitudinal direction. It is a manufacturing apparatus for manufacturing an aluminum member for a current collector. That is, the manufacturing apparatus 50 is a manufacturing apparatus that carries out each step by roll-to-roll (RtoR) to manufacture an aluminum member for a current collector.

The manufacturing apparatus 50 includes a rotary shaft 52 loaded with a base material roll 70, an electrolysis process unit 56 for performing an electrolysis process, a partial removal process unit 58 for performing a partial removal process, and a cleaning / drying process for performing a cleaning / drying process. It has a process unit 60 and a take-up shaft 54 that winds up the aluminum member 10 for a current collector manufactured by each treatment into a roll 72 shape. The electrolysis process unit 56, the partial removal process unit 58, and the washing / drying process unit 60 are arranged on a path in which the aluminum base material 1 is conveyed from the rotary shaft 52 to the take-up shaft 54.

In the manufacturing apparatus 50, the delivery of the aluminum base material 1 from the base material roll 70 and the winding of the current collector aluminum member 10 on the take-up shaft 54 are performed in synchronization with each other to perform the long aluminum base material 1. The aluminum base material 1 is subjected to the above-mentioned treatments in each process section while the aluminum substrate 1 is transported in the longitudinal direction by a predetermined transport path.

Note that, on the upstream side or the downstream side of the electrolytic process unit 56, a through hole forming process unit for performing a through hole forming step and / or a roughening process unit for performing a roughening process may be provided. Further, the electrolysis step unit 56 may carry out a through hole forming step and / or a roughening step in addition to the electrolysis step.

Further, in the manufacturing apparatus 50, each step is carried out by RtoR using a long aluminum base material 1, but the present invention is not limited to this, and each step is carried out using a single-wafer-shaped aluminum base material 1. You may. Moreover, each step may be carried out by another apparatus.

[Current collector]
As described above, the aluminum member for a current collector of the present invention can be used as a current collector for a power storage device (hereinafter, also referred to as a “current collector”).
By having an island-shaped anodic oxide film, the current collector can achieve both improved adhesion to the electrode material and low resistance, which contributes to the reduction of internal resistance and is charged and discharged many times over a long period of time. Even when the above is performed, partial peeling between the electrode material (active material) and the current collector can be suppressed.

<Electrode material (active material)>
The active material is not particularly limited, and known active materials used in conventional power storage devices can be used.
Specifically, when the aluminum member for a current collector is used as the current collector of the positive electrode, the conductive material, the binder, the solvent and the like which may be contained in the active material and the active material layer are described in JP-A-2012. The materials described in paragraphs [0077] to [0088] of the publication No. 216513 can be appropriately adopted, and the contents thereof are incorporated herein by reference.
Further, when the aluminum member for a current collector is used as the current collector of the negative electrode, the material described in paragraph [089] of JP2012-216513A can be appropriately adopted as the active material. The content is incorporated herein by reference.

[Positive electrode]
The positive electrode using the aluminum member for a current collector of the present invention as a current collector is a positive electrode current collector using the aluminum member for a current collector as a positive electrode and a positive electrode active material formed on the surface of the positive electrode current collector. It is a positive electrode having a layer containing (positive electrode active material layer).
Here, the positive electrode active material, the conductive material, the binder, the solvent and the like which may be contained in the positive electrode active material layer are described in paragraphs [0077] to [0088] of JP2012-216513A. The materials described may be adopted as appropriate and their contents are incorporated herein by reference.

[Negative electrode]
The negative electrode using the aluminum member for the current collector of the present invention as the current collector is a negative electrode current collector using the aluminum member for the current collector as the negative electrode and a negative electrode active material formed on the surface of the negative electrode current collector. It is a negative electrode having a layer containing it.
Here, as the negative electrode active material, the material described in paragraph [089] of JP2012-216513A can be appropriately adopted, and the content thereof is incorporated as a reference in the present specification.

[Power storage device]
The electrode using the aluminum member for the current collector of the present invention as a current collector is a secondary using a lithium ion battery, a lithium ion capacitor, an electric double layer capacitor, a semi-solid battery, a solid battery, and a non-aqueous electrolyte solution. It can be used as a positive electrode or a negative electrode of a power storage device such as a battery.
Here, regarding the specific configuration of the power storage device (particularly, the secondary battery) and the applicable use, the materials and uses described in paragraphs [0090] to [0123] of JP2012-216513A can be appropriately used. It can be adopted and its contents are incorporated herein by reference.

[Electric double layer capacitor]
The electric double layer capacitor is a capacitor having an electric double layer as a dielectric and having a capacitor structure of facing electrodes. An electric double layer is a state in which electrons or holes are attracted to each other and aligned by charging, which occurs spontaneously between a solid and a liquid. A specific configuration of the electric double layer capacitor is described in, for example, Japanese Patent Application Laid-Open No. 2020-064971.
The aluminum member for a current collector of the present invention can be used as the current collector of the positive electrode and / or the negative electrode of the electric double layer capacitor.

[Lithium-ion capacitor]
A lithium ion capacitor is a negative electrode doped with lithium ions while using the principle of a general electric double layer capacitor. The specific configuration of the lithium ion capacitor is described in, for example, International Publication No. 2016/084704 and the like.
The aluminum member for a current collector of the present invention can be used as the current collector of the positive electrode and / or the negative electrode of the lithium ion capacitor.

[Solid-state battery]
A solid-state battery is a battery in which a solid electrolyte is responsible for conducting ions between the anode and the cathode. The specific configuration of the solid-state battery is described in, for example, Japanese Patent Application Laid-Open No. 2020-1235338.
The aluminum member for a current collector of the present invention can be used as the positive electrode and / or the current collector of the negative electrode of the solid-state battery.

[Semi-solid state battery]
A semi-solid state battery is a battery in which a semi-solid (gel-like or clay-like) electrolyte is responsible for the conduction of ions between the anode and the cathode. The specific configuration of the semi-solid state battery is described in US Pat. No. 4,948,569 and the like.
The aluminum member for a current collector of the present invention can be used as the positive electrode and / or the current collector of the negative electrode of the semi-solid state battery.

[Secondary battery using non-aqueous electrolyte]
A secondary battery that uses a non-aqueous electrolytic solution is a secondary battery that uses a non-aqueous electrolytic solution as the electrolytic solution between the anode and the cathode. A specific configuration of a secondary battery using a non-aqueous electrolytic solution is described in Japanese Patent Application Laid-Open No. 2017-068978 and the like.
The aluminum member for a current collector of the present invention can be used as a current collector for the positive electrode and / or the negative electrode of a secondary battery using a non-aqueous electrolytic solution.

The present invention will be described in more detail below based on examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limiting by the examples shown below.

[Manufacturing of aluminum members for current collectors]
Using an aluminum base material having an alloy number of 1085 or 1N30 having a thickness of 20 μm as the aluminum base material, one of the following electrolytic treatments and partial removal treatments or film removal treatments is carried out to collect electricity, which is an aluminum member for a current collector. Body A to current collector S were produced. The current collector F to the current collector O correspond to the embodiment of the present invention.

<Electrolysis treatment A>
An aqueous solution containing 20 g / l of nitric acid and 20 g / l of sulfuric acid (liquid temperature 50 ° C.) was subjected to electrolytic treatment using an aluminum substrate as an anode to form an anodic oxide film on the surface of the aluminum substrate. The electrolytic treatment was performed with a DC power supply. The conditions for the electrolytic treatment were a direct current density of 5 A / dm ² , a direct current voltage of 8 V, and an application time of 30 seconds. The anodic oxide film formed by this electrolytic treatment has fine pores having a diameter of 1 to 30 nm.

<Electrolysis treatment B>
AC electrolysis was performed in an aqueous solution containing 10 g / l of hydrochloric acid (liquid temperature 35 ° C.) to form a rough surface on the surface. After washing with water, an aqueous solution containing 20 g / l of nitric acid and 20 g / l of sulfuric acid (liquid temperature 50 ° C.) was used to perform electrolytic treatment using the aluminum base material as an anode to form an anodic oxide film on the surface of the aluminum base material. The electrolytic treatment was performed with a DC power supply. The conditions for the electrolytic treatment were a direct current density of 5 A / dm ² , a direct current voltage of 8 V, and an application time of 120 seconds. The anodic oxide film formed by this electrolytic treatment has fine pores having a diameter of 1 to 30 nm.

<Electrolysis treatment C>
Using an aqueous solution containing 20 g / l of nitric acid and 20 g / l of sulfuric acid (liquid temperature 50 ° C.), electrolytic treatment is performed using the aluminum base material as an anode to form an anodic oxide film on the surface of the aluminum base material, and the aluminum base material is formed. A through hole was formed to penetrate. The electrolytic treatment was performed with a DC power supply. The conditions for the electrolytic treatment were a direct current density of 5 A / dm ² , a direct current voltage of 8 V, and an application time of 120 seconds. The anodic oxide film formed by this electrolytic treatment has fine pores having a diameter of 1 to 30 nm.

<Electrolysis treatment D>
Using a solution of 170 g / l of sulfuric acid and an Al ion concentration of 5% (liquid temperature 50 ° C.), electrolytic treatment was performed using an aluminum substrate as an anode to form an anodic oxide film on the surface of the aluminum substrate. The electrolytic treatment was performed with a DC power supply. The conditions for the electrolytic treatment were a direct current density of 25 A / dm ² , a direct current voltage of 15 V, and an application time of 16 seconds.

<Electrolysis treatment E>
Using a solution of 170 g / l of sulfuric acid and an Al ion concentration of 5% (liquid temperature 50 ° C.), electrolytic treatment was performed using an aluminum substrate as an anode to form an anodic oxide film on the surface of the aluminum substrate. The electrolytic treatment was performed with a DC power supply. The conditions for the electrolytic treatment were a direct current density of 5 A / dm ² , a direct current voltage of 3 V, and an application time of 27 seconds. After the electrolytic treatment, when the partial removal treatment was not performed, washing with water and drying were performed.

<Electrolysis treatment F>
Using a solution having a sulfuric acid concentration of 30% (liquid temperature 0 ° C.), electrolytic treatment was performed using an aluminum substrate as an anode to form an anodic oxide film on the surface of the aluminum substrate. The electrolytic treatment was performed with a DC power supply. The conditions for the electrolytic treatment were a direct current density of 3 A / dm ² , a direct current voltage of 50 V, and an application time of 30 minutes twice. After the electrolytic treatment, it was washed with water and dried.

<Partial removal process A>
The surface was washed for 5 seconds with an aqueous solution containing 75 g / l of NaOH (liquid temperature 35 ° C.). Then, it was washed with water, pickled and washed with water and dried.

<Partial removal process B>
The surface was washed for 10 seconds with an aqueous solution containing 75 g / l of NaOH (liquid temperature 35 ° C.). Then, it was washed with water, pickled and washed with water and dried.

<Partial removal process C>
The surface was washed for 5 seconds with an aqueous solution containing 75 g / l of NaOH (liquid temperature 25 ° C.). Then, it was washed with water, pickled and washed with water and dried.

<Partial removal process D>
After passing through a set of metal rolls (hard chrome plated finish, diameter 50 mm, passing speed 10 m / s), the surface was rubbed with a rotating brush roll to partially remove the anodic oxide film. Then, it was pickled and washed with water and dried.

<Film removal treatment A>
The anodic oxide film was removed by immersing in phosphoric acid at 30 ° C. for 30 minutes. Then it was washed with water and dried.

<Film removal treatment B>
The anodic oxide film was removed by immersing in a solution (liquid temperature 35 ° C.) of NaOH 5% (50 g / l) and aluminum ion concentration 0.5% (5 g / l) for 3 seconds. Then it was washed with water and dried.

After manufacturing the aluminum member for each current collector, the coverage of the anodic oxide film, the number density of micropores, the average diameter, and the thickness of the anodic oxide film were measured by the above-mentioned method.
Table 1 shows the treatment in each current collector aluminum member, the coverage, the thickness, the number density of micropores, and the average diameter of the anodic oxide film.
Further, the SEM image of the current collector F is shown in FIG. 11, and the SEM image of the current collector S is shown in FIG. It can be seen that the anodic oxide film 214 of the current collector S, which is a comparative example, has inhomogeneous micropores as compared with the anodic oxide film 14 of the current collector F, which is an example.

[Examples 1 to 10, Comparative Examples 1 to 9]
The following slurry for a positive electrode was applied to the produced aluminum members for a current collector (current collectors A to S) to form an active material layer, and the adhesion and resistance were evaluated.

<Preparation of slurry for positive electrode>
The following materials were prepared as a slurry for the positive electrode.
・ Positive electrode active material: Powdered activated carbon as a raw material for coconut shell (YP: manufactured by Kuraray Co., Ltd.)
88% by mass
-Binder: Acrylic resin (AZ-9129: Made by Nippon Zeon Corporation)
3% by mass
・ Conductive aid: Acetylene Black (Denka Black: manufactured by Denki Kagaku Kogyo Co., Ltd.) 15% by mass
・ Thickener: CMC (manufactured by Daicel FineChem Co., Ltd.) 1% by mass
・ Water 220% by mass

Materials other than the binder and water were stirred with a self-revolving variable stirrer (Mazelstar: manufactured by Kurabo Industries Ltd.). Next, the mixture was stirred with a high-speed homogenizer. Finally, a binder was added, and the mixture was stirred again with a self-revolving variable stirrer to obtain a slurry for a positive electrode.

<Application of slurry for positive electrode>
The slurry for the positive electrode was applied to one side of the aluminum member for the current collector so that the mass of activated carbon after drying was 3 mg / cm ² . The surface was smoothed by passing it through a calendar roll after application and drying. As a result, an active material layer was formed on one side of the current collector aluminum member.

In Comparative Example 2, the undercoat layer of the conductive material was formed as follows before applying the slurry for the positive electrode.

<Formation of undercoat layer>
A graphite material (Bunny Height: manufactured by Nippon Graphite Industry Co., Ltd.) was applied with an applicator to a thickness of 3 μm, and dried at a drying temperature of 100 ° C. for 10 minutes to form an undercoat layer.

[evaluation]
<Adhesion>
A peeling test was conducted on the current collector aluminum member on which the active material layer was formed for the purpose of evaluating the adhesion between the current collector aluminum member and the active material layer.
For the peeling test, a peeling tester manufactured by Imada Co., Ltd. was used. In the peeling test, the digital force gauge 162 was attached to a vertical test table, and the sample S was fixed to the sticking table 154 on the 90-degree peeling test slide table 152 with double-sided tape 156 with the active material layer side facing up. The method of measuring the load when peeling off the adhesive tape 158 attached to the active material layer was performed. In order to evaluate the adhesion of the interface between the aluminum member for the current collector and the active material layer, an adhesive tape having a width of 25 mm having sufficient adhesive strength was used. The evaluation was performed by the average value of the loads measured by the digital force gauge 162 during peeling. FIG. 13 shows a schematic diagram of the peeling test evaluation device.

<Resistance>
In the resistance evaluation, as shown in FIG. 14, each current collector aluminum member 10 having the active material layer 106 formed thereof is sandwiched between the pressurized conductive dedicated terminal 102 and the pressurized insulating terminal 104, and the resistance measuring machine 100 (Hioki). The resistance was measured with 1 sample N = 7 with HIOKI3541) manufactured by HIOKI Co., Ltd.
The initial resistance evaluation was performed after storing in DRYBOX for 24 hours or more before the evaluation.
Next, forced time resistance evaluation was performed. Each current collector aluminum member was stored in an environment of temperature 30 ° C. and humidity 80%, and after 2 weeks, the electrode slurry was applied and dried by the above-mentioned method to evaluate the resistance. Similarly, resistance evaluation was performed after storage for 4 weeks in an environment of temperature 30 ° C. and humidity 80%.
The results are shown in Table 2.

From Table 2, it can be seen that Examples 1 to 10 of the present invention can achieve both high adhesion and low resistance as compared with Comparative Examples 1 to 9.

Since the surfaces of Comparative Examples 1, 2 and 6 were not treated, the surface of the current collector foil was smooth, the adhesion to the active material layer was weak, and the peel strength was small. In Comparative Example 2, the adhesion with the active material layer was slightly improved by applying the carbon undercoat, but it was not sufficient. In Comparative Example 7, unevenness was formed on the surface, but it was not at a level where adhesion could be improved. Comparative Example 7 was produced by a method according to Patent Document 3, and the aluminum member for a current collector produced by this method has irregularities on the surface, but the fine pores of the anodic oxide film are obtained in terms of adhesion. It shows that it does not reach the effect of.

Comparative Examples 3, 4, and 5 have a configuration in which an anodic oxide film remains on the entire surface. Since the surface has a micropore structure, the adhesion is superior to that of the current collector foil having a smooth surface, but the resistance is very poor. This means that the resistance of the aluminum member for a current collector provided with the anodic oxide film shown in Patent Document 4 does not reach that of the aluminum member for a current collector of the present invention.

As a result of SEM observation, in Comparative Example 8, since the anodic oxide film having fine pores remained on the entire surface, the peel strength was high, but the resistance was extremely poor as in Comparative Examples 3, 4 and 5. As a result of SEM observation in Comparative Example 9, an anodic oxide film having no micropores covered about 30% of the surface. It was found that the adhesion was low and the resistance was inferior because it did not have micropores. The reason why the resistance is inferior is considered to be that the natural oxide film is thick.

In the embodiment of the present invention, it can be seen that the resistance can be lowered because the aluminum base material is exposed by partially removing the anodic oxide film on the surface formed by each electrolytic treatment. These have smaller resistance and are better than Comparative Examples 1 and 6 without surface treatment. This is because the natural oxide film formed in the rolling process of the aluminum base material is present on the surface of the aluminum base material without surface treatment, so that the resistance is considered to be large. Since the natural oxide film formed on the surface of the aluminum base material exposed after the film is partially removed is very thin, it is considered that the resistance can be lowered.

The resistance of the examples is at the same level as that of the current collector foil (Comparative Example 2) coated with conductive carbon, which is generally performed for the purpose of reducing the resistance between the active material layer and the aluminum member for the current collector. Met.
When the aluminum member for a current collector is stored at high humidity, the natural oxide film on the outermost surface of the aluminum base material tends to grow and the resistance tends to deteriorate. However, the examples of the present invention have higher humidity than the comparative examples. The deterioration of resistance due to storage could be suppressed from the same level to less than that.
Since the through holes are formed in Examples 7 and 10, it is considered that a part of the active material layer enters the holes and the adhesion is slightly improved with respect to Example 1.

[Examples 11 to 16, Comparative Example 10]
In Examples 11 to 16 and Comparative Example 10, the positive electrode active material of the semi-solid state battery is used as the active material layer. The current collectors F to K were used in Examples 11 to 16, and the current collector A was used in Comparative Example 10.
The following positive electrode material was applied to the aluminum member for the current collector to form an active material layer, and the adhesion and resistance were evaluated.

<Manufacturing of positive electrode material>
The following materials were prepared as materials for the positive electrode.
-Positive electrode active material: Lithium cobalt oxide (LiCoO ₂ ) 99% by mass
・ Conductive aid: Acetylene Black (Denka Black: manufactured by Denki Kagaku Kogyo Co., Ltd.) 1% by mass
As the electrolytic solution, an electrolytic solution in which 1.5 mol / kg of the electrolyte salt LiPF ₆ was added to ethylene carbonate was used.

A clay-like positive electrode material was prepared by kneading the positive electrode active material and the conductive auxiliary agent, adding an electrolytic solution, and further kneading.

<Application of positive electrode material>
The material for the positive electrode was applied to one side of the aluminum member for the current collector. For application, a stainless steel plate with a thickness of 2 mm and a square opening with a length of 75 m and a width of 50 mm is placed on each aluminum member for a current collector cut into a length of 150 mm and a width of 70 mm. The active material was put in the opening, and a squeegee was used so that the coating thickness was about 2 mm.

[evaluation]
<Adhesion>
The aluminum member for the current collector coated with the material for the positive electrode is wound around a round bar made of stainless steel having a diameter of 50 mm so that the active material layer is on the outside, rewound, and the active material layer and the aluminum member for the current collector are peeled off. The situation was visually observed.
Visually, the case where the peeling did not occur at the interface between the active material layer and the aluminum member for the current collector was evaluated as A, and the case where the peeling occurred was evaluated as B.
The results are shown in Table 3.

From the results in Table 3, it can be seen that in the examples, peeling did not occur and the adhesion was high.

[Examples 17 to 19, Comparative Example 11]
In Examples 17 to 19 and Comparative Example 11, cells of a semi-solid-state battery were produced. In Examples 17 to 19, the positive electrodes prepared in Examples 11 to 13 were used as the positive electrodes, and in Comparative Example 11, the positive electrodes prepared in Comparative Example 10 were used. The negative electrode was manufactured as follows.

<Manufacturing of negative electrode>
The following materials were prepared as materials for the negative electrode.
-Negative electrode active material: Graphite 99% by mass
-Conductive aid: Acetylene Black (manufactured by Denka Black Electrochemical Industry Co., Ltd.) 1% by mass
As the electrolytic solution, an electrolytic solution in which 1.5 mol / kg of the electrolyte salt LiPF ₆ was added to ethylene carbonate was used.

A clay-like negative electrode material was prepared by kneading the negative electrode active material and the conductive auxiliary agent, adding an electrolytic solution, and further kneading.

A copper foil with a thickness of 10 μm (using an electrolytic copper foil) is prepared as a current collector for the negative electrode, and a negative electrode material is applied to one side of the copper foil with a squeegee to form an active material layer with a thickness of about 2 mm to form a negative electrode. Was produced.

<Manufacturing of semi-solid battery cell>
After welding the tabs, the positive and negative electrodes were combined and sealed in a pouch to prepare a semi-solid-state battery cell.

[evaluation]
<Internal resistance increase rate and capacity maintenance rate>
Using the prepared semi-solid-state battery cell, the battery was charged to 4.2 V at a constant current of 1 mA at 20 ° C., and then discharged to 3 V. This charging / discharging is repeated 110 times, the capacity and internal resistance at the 10th and 110th times are recorded, and the 110th internal resistance increase rate and capacity maintenance rate when the 10th capacity and resistance are set to 100%, respectively. Was evaluated.
The results are shown in Table 4.

From Table 4, it can be seen that the examples of the present invention have the same or higher capacity retention rate and internal resistance increase rate as compared with the comparative examples.
From the above, the effect of the present invention is clear.

1 Aluminum base material 2 Anodized film 3 Aluminum base material with through holes 4 Anodized film with through holes 5 Through holes 10, 10b Aluminum member for current collector 14 Island-shaped anodized film 50 Manufacturing equipment 52 Rotating shaft 54 Winding shaft 56 Electric field process part 58 Partial removal process part 60 Cleaning and drying process part 70 Base material roll 72 roll 100 Resistance measuring instrument 102 Pressurized conductive dedicated terminal 104 Pressurized insulating terminal 106 Active material layer 150 Slide rail 152 Slide table 154 pasted Attachment 156 Double-sided tape 158 Adhesive tape 160 Clamp 162 Digital force gauge 164 Pulling device 201 Aluminum base material 214 Anodized film S Evaluation sample

Claims (13)

1. An aluminum member for a current collector having an aluminum base material and an anodic oxide film on the aluminum base material.
   The anodic oxide film has a large number of micropores and has a large number of micropores.
   The coverage of the anodic oxide film on at least one surface of the aluminum substrate is 1 to 80%.
   An aluminum member for a current collector having a number density of 600 micropores / μm ² or more in the anodic oxide film.
2. The aluminum member for a current collector according to claim 1, wherein the anodic oxide film exists in an island shape on the aluminum base material.
3. The aluminum member for a current collector according to claim 1 or 2, wherein the micropores have an average diameter of 1 nm to 100 nm.
4. The aluminum member for a current collector according to any one of claims 1 to 3, wherein the anodic oxide film has a thickness of 1 nm to 30 nm.
5. The aluminum member for a current collector according to any one of claims 1 to 4, wherein the aluminum base material has a granular intermetallic compound on the surface.
6. The aluminum member for a current collector according to claim 5, wherein the surface of the aluminum base material has 500 pieces / mm ² or more of the granular intermetallic compound.
7. The aluminum member for a current collector according to any one of claims 1 to 6, wherein the thickness of the aluminum base material is 5 μm to 100 μm.
8. The aluminum member for a current collector according to any one of claims 1 to 7, wherein the aluminum member for a current collector has a plate shape.
9. A lithium ion capacitor having an aluminum member for a current collector according to any one of claims 1 to 8.
10. An electric double layer capacitor having an aluminum member for a current collector according to any one of claims 1 to 8.
11. A semi-solid battery having the aluminum member for a current collector according to any one of claims 1 to 8.
12. A solid-state battery having the aluminum member for a current collector according to any one of claims 1 to 8.
13. A secondary battery using a non-aqueous electrolytic solution having the aluminum member for a current collector according to any one of claims 1 to 8.

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