WO2019207964A1 - Aluminum porous body, electrode, electricity storage device, and method for producing aluminum porous body - Google Patents

Abstract

A sheet-like aluminum porous body having a three-dimensional net-like structure backbone, wherein the surface roughness Ra of the skeleton is 3 μm or more and the compression strength of the aluminum porous body as measured in the thickness direction is 1.0 MPa or more.

Description

Porous aluminum body, electrode, power storage device, and method for producing porous aluminum body

The present disclosure relates to an aluminum porous body, an electrode, an electricity storage device, and a method for producing the aluminum porous body.
This application claims priority based on Japanese Patent Application No. 2018-087171 filed on Apr. 27, 2018, and incorporates all the content described in the above Japanese application.

Metal porous bodies having a skeleton having a three-dimensional network structure (hereinafter also simply referred to as “metal porous bodies”) are used in various fields such as various filters, catalyst carriers, and battery electrodes. For example, aluminum cermet (registered trademark) manufactured by Sumitomo Electric Industries, Ltd., which is a metal porous body made of aluminum, is stable even in an organic electrolyte, and can be used as a positive electrode of a lithium ion battery.

The metal porous body having a three-dimensional network structure skeleton is characterized by a high porosity (90% or more) compared to other porous bodies such as a metal nonwoven fabric. Therefore, by filling the pores of the metal porous body with an active material and using it as an electrode of a power storage device such as a lithium ion battery, the utilization rate of the active material per unit area can be improved and the power storage with a large power storage capacity can be achieved. A device can be provided.

As a method for producing a metal porous body made of aluminum, for example, methods described in International Publication No. 2012/111605 (Patent Document 1) and International Publication No. 2012/111665 (Patent Document 2) are known.

International Publication No. 2012/111605 International Publication No. 2012/111665

The aluminum porous body of the present disclosure is a sheet-like aluminum porous body having a skeleton having a three-dimensional network structure, the surface roughness Ra of the skeleton being 3 μm or more, and the compressive strength in the thickness direction of the aluminum porous body. Is a porous aluminum body having 1.0 MPa or more.

The method for producing a porous aluminum body of the present disclosure includes a conductive treatment step of forming a conductive layer on the surface of a skeleton of a resin molded body having a skeleton having a three-dimensional network structure, and aluminum on the surface of the skeleton of the resin molded body. A plating process for obtaining a resin structure by electrodeposition, and a resin removal process for removing the resin molded body and the conductive layer from the resin structure to obtain a porous aluminum body. The solution contains 5.0 g / L or more and 7.5 g / L or less of 1,10-phenanthroline as an additive, and the amount of the electrolyte remaining on the surface of the skeleton of the resin structure in the resin removal step However, cleaning is performed in a state where the apparent area of the resin structure is 35 ml / m ² or more and 200 ml / m ² or less, and the basis weight is 50 g / m ² or more and 200 g / m per 1 mm thickness. It is a manufacturing method of the aluminum porous body which obtains the aluminum porous body which is ² or less.

It is the schematic showing an example of the aluminum porous body concerning the embodiment of this indication. It is a cross-sectional photograph of an example of the aluminum porous body which concerns on embodiment of this indication. It is an enlarged view showing the outline of the partial section of an example of the aluminum porous body concerning the embodiment of this indication. It is an enlarged view showing the outline of a partial section of an example of the state where the conductive layer was formed in the surface of the frame of a resin fabrication object. It is a photograph of urethane foam resin of an example of the resin molding which has frame | skeleton of a three-dimensional network structure. It is an enlarged view showing the outline of a partial section of an example of the state where the aluminum film was further formed in the surface of the conductive layer formed in the surface of the frame of a resin fabrication object. It is a cross-sectional schematic diagram which shows the structural example which applied the aluminum porous body to the lithium ion battery. Porous aluminum body No. 1 produced in the examples. It is the photograph which observed the cross section of 2 with the scanning microscope. It is an enlarged photograph of the part enclosed with the white frame in FIG.

[Problems to be solved by the present disclosure]
The present inventors examined using a porous metal body (hereinafter referred to as “aluminum porous body”) whose skeleton is composed of a metal mainly composed of aluminum as a current collector in an electrode of an electricity storage device. . In order to increase the storage capacity of the power storage device, it is effective to increase the contact area between the active material filled in the pores of the skeleton of the aluminum porous body, which is a current collector, and the skeleton. When producing a porous aluminum body by a method of plating aluminum on the surface of a substrate having a three-dimensional network skeleton (so-called plating method), the concentration of phenanthroline added to the molten salt (electrolytic solution) should be low. By doing so, an aluminum porous body having a rough skeleton surface can be produced. However, it has been found that when a porous aluminum body is produced using a molten salt having a low phenanthroline concentration, the compressive strength of the skeleton is reduced.

Therefore, an object of the present disclosure is to provide a porous aluminum body having high strength and a rough skeleton surface.

[Effects of the present disclosure]
According to the present disclosure, an aluminum porous body having high strength and a rough skeleton surface can be provided.

[Description of Embodiment of Present Disclosure]
First, embodiments of the present disclosure will be listed and described.
(1) An aluminum porous body according to one embodiment of the present disclosure is:
A sheet-like aluminum porous body having a three-dimensional network structure skeleton,
The surface roughness Ra of the skeleton is 3 μm or more,
The compressive strength in the thickness direction of the aluminum porous body is 1.0 MPa or more,
A porous aluminum body.
According to the aspect of the invention described in (1), it is possible to provide a porous aluminum body having high strength and a rough skeleton surface.

(2) The aluminum porous body according to (1) is
Basis weight per a thickness of 1 mm, 50 g / ^{m 2} or more and 200 g / ^{m 2} or less.
According to the aspect of the invention described in (2) above, it is possible to provide a porous aluminum body that is lightweight and has high strength.

(3) The aluminum porous body according to (1) or (2) above,
The average pore diameter is preferably 300 μm or more and 3500 μm or less.
According to the aspect of the invention described in (3), when used as a current collector for an electrode of an electricity storage device, the amount of active material retained is large and the active material utilization efficiency can be increased. An aluminum porous body can be provided.

(4) The aluminum porous body according to any one of (1) to (3),
The thickness is preferably 0.6 mm or more and 10.0 mm or less.
According to the aspect of the invention described in (4) above, it is possible to provide a porous aluminum body that is lightweight and has high strength.

(5) An electrode according to one embodiment of the present disclosure is provided.
It is an electrode provided with the aluminum porous body as described in any one of said (1) to said (4) as a collector.
According to the aspect of the invention described in (5), it is possible to provide an electrode having a large contact area between the active material filled in the pores of the skeleton of the porous aluminum body and the skeleton and having excellent compressive strength. .

(6) An electricity storage device according to one embodiment of the present disclosure is provided.
It is an electrical storage device provided with the aluminum porous body as described in any one of said (1) to said (4) as a collector.
According to the aspect of the invention described in (6), it is possible to provide an electricity storage device including an electrode having high active material utilization efficiency and high strength.

(7) A method for producing a porous aluminum body according to one embodiment of the present disclosure includes:
A conductive treatment step of forming a conductive layer on the surface of the skeleton of the resin molded body having a skeleton of a three-dimensional network structure;
A plating step of obtaining a resin structure by electrodepositing aluminum on the surface of the skeleton of the resin molded body;
A resin removal step of removing the resin molded body and the conductive layer from the resin structure to obtain an aluminum porous body;
Including
The electrolytic solution used in the plating step contains 5.0 g / L or more and 7.5 g / L or less of 1,10-phenanthroline as an additive,
In the resin removal step, the amount of the electrolyte remaining on the surface of the skeleton of the resin structure is 35 ml / m ² or more and 200 ml / m ² or less based on the apparent area of the resin structure. Cleaning in a certain state,
Basis weight per a thickness of 1 mm, 50 g / ^{m 2} or more to obtain a porous aluminum body is 200 g / ^{m 2} or less,
A method for producing a porous aluminum body.
According to the aspect of the invention described in (7), a method for producing a porous aluminum body having high strength and a rough skeleton surface can be provided.

[Details of Embodiments of the Present Disclosure]
Specific examples of the porous aluminum body, the electrode, and the electricity storage device according to the embodiment of the present disclosure will be described in more detail below. In addition, this indication is not limited to these illustrations, is shown by the claim, and is intended to include all the changes within the meaning and range equivalent to the claim.

<Porous aluminum body>
Conventional aluminum porous bodies have room for improvement in that the compressive strength in the thickness direction decreases as the surface roughness of the skeleton increases. As a result of detailed studies by the inventors, in order to produce an aluminum porous body having a large skeleton surface roughness, the concentration of phenanthroline added to the molten salt (electrolytic solution) for plating aluminum is lowered. Although it is necessary, when it did so, the thickness of the aluminum film which comprises the frame | skeleton of an aluminum porous body became non-uniform | heterogenous, and it discovered that this became the cause of reducing the compressive strength of a frame | skeleton.
That is, the surface roughness of the skeleton of the porous aluminum body and the compressive strength in the thickness direction had a trade-off relationship. The aluminum porous body according to the embodiment of the present disclosure solves this problem, and has an unprecedented property that the surface roughness Ra of the skeleton is large and the compressive strength in the thickness direction is large. .

Below, the structure of the aluminum porous body which concerns on embodiment of this indication is explained in full detail, referring drawings suitably.
FIG. 1 shows a schematic diagram of an example of an aluminum porous body according to an embodiment of the present disclosure.
As shown in FIG. 1, the porous aluminum body 10 according to an embodiment of the present disclosure has a three-dimensional network structure skeleton, and has a sheet-like appearance as a whole. The pores formed by the skeleton of the three-dimensional network structure are continuous ventilation holes formed so as to continue from the surface to the inside of the porous aluminum body 10. Note that the skeleton only needs to be mainly composed of the aluminum film 11 and may contain a metal or an alloy other than aluminum intentionally or inevitably as long as the effects of the present disclosure are not impaired.

FIG. 2 shows an enlarged photograph showing a skeleton of a three-dimensional network structure as an example of the aluminum porous body according to the embodiment of the present disclosure. Moreover, the enlarged schematic diagram which expanded the cross section of the aluminum porous body shown in FIG. 2 is shown in FIG.
When the shape of the skeleton has a three-dimensional network structure, typically, as shown in FIG. 3, the skeleton 12 of the aluminum porous body 10 is constituted by an aluminum film 11, and the inside 13 of the skeleton 12 is hollow. It has become. Moreover, the pore part 14 formed of the skeleton 12 is a continuous ventilation hole as described above.

The surface roughness Ra of the skeleton of the aluminum porous body 10 according to the embodiment of the present disclosure is 3 μm or more. The surface roughness of the skeleton refers to the surface roughness of the surface of the aluminum film 11 forming the skeleton 12 on the side in contact with the pores 14. The surface roughness Ra refers to a value obtained by measuring an area of 25 μm × 25 μm for a porous aluminum body with a laser surface roughness meter at five points and averaging the arithmetic average roughness Ra in each area. Since the skeleton of the porous aluminum body has a three-dimensional network structure and is greatly curved depending on the location, when measuring the surface roughness Ra of the skeleton, an area of 25 μm × 25 μm is formed on the surface of the skeleton. What is necessary is just to select and measure the part as close to the plane as possible.

When the surface roughness Ra of the skeleton is 3 μm or more, for example, when the aluminum porous body 10 is used as a current collector of an electrode of an electricity storage device, the contact area between the active material filled in the pores 14 and the skeleton Can be increased. Further, from the viewpoint of preventing the strength of the skeleton from becoming small, the surface roughness Ra of the skeleton of the aluminum porous body 10 is preferably 10 μm or less. From these viewpoints, the surface roughness Ra of the skeleton is preferably 3 μm or more and 10 μm or less, and more preferably 3 μm or more and 5 μm or less.

The porous aluminum body 10 according to the embodiment of the present disclosure has a compressive strength in the thickness direction of 1.0 MPa or more. The compressive strength of the porous aluminum body 10 means that when a test piece is prepared by punching a sheet-like aluminum porous body to 20 mmφ and a load is applied in the thickness direction of the test piece with a compression tester, The load necessary to reduce the thickness by 5% shall be said.

When the compressive strength in the thickness direction of the aluminum porous body 10 is 1.0 MPa or more, for example, when the aluminum porous body 10 is used as a current collector of an electrode of an electricity storage device, an active material is formed in the pores 14 of the aluminum porous body 10. The aluminum porous body 10 can maintain a three-dimensional network structure even if the pressure during filling is increased. That is, the pressure at the time of filling the pores 14 with the active material can be increased. The compressive strength in the thickness direction of the porous aluminum body 10 is preferably as large as possible, more preferably 1.2 MPa or more, and even more preferably 1.5 MPa or more. Since the aluminum porous body 10 has a skeleton composed of the aluminum film 11 and is hollow inside, the compressive strength in the thickness direction is approximately 3.0 MPa or less.

Aluminum porous body 10, basis weight per a thickness of 1 mm, 50 g / ^{m 2} or more and 200 g / ^{m 2} or less. In addition, since the thickness and the basis weight of the aluminum porous body 10 are proportional, for example, when the thickness is 2 mm, a preferable range of the basis weight is 100 g / m ² or more and 400 g / m ² or less. Further, the basis weight is the apparent mass per unit area of the main surface of the sheet-like porous aluminum body.
When the basis weight of the porous aluminum body is 50 g / m ² or more per 1 mm thickness, the compressive strength in the thickness direction can be further increased. Moreover, when the basis weight of the aluminum porous body is 200 g / m ² or less per 1 mm thickness, an increase in manufacturing cost and an increase in weight can be suppressed. From these viewpoints, the basis weight of the porous aluminum thickness 1mm per 70 g / ^{m 2} or more, 180 g / ^{m 2} or less is more preferably 80 g / ^{m 2} or more, more preferably 160 g / ^{m 2} or less.

The aluminum porous body 10 preferably has an average pore diameter of 300 μm or more and 3500 μm or less. When the average pore diameter of the aluminum porous body 10 is 300 μm or more, when the aluminum porous body 10 is used as a current collector of an electrode of an electricity storage device, the amount of active material filled in the pores 14 may be increased. it can. Further, since the average pore diameter of the aluminum porous body 10 is 3500 μm or less, when the aluminum porous body 10 is used as a current collector of an electrode of an electricity storage device, contact between the active material filled in the pores 14 and the skeleton The area can be increased and the utilization efficiency of the active material can be improved. From these viewpoints, the average pore diameter of the porous aluminum body 10 is more preferably 500 μm or more and 2000 μm or less, and further preferably 550 μm or more and 900 μm or less.
In addition, an average pore diameter is the value calculated | required from the reciprocal number of the cell number of the aluminum porous body. The number of cells is a numerical value obtained by counting the number of cells on the outermost surface intersecting the line when a line of 1 inch in length is drawn on the surface (main surface) of the sheet-like porous aluminum body. Pieces / inch.
However, 1 inch shall be 2.54 cm.

The aluminum porous body 10 preferably has a thickness of 0.6 mm or more and 10.0 mm or less. When the aluminum porous body 10 has a thickness of 0.6 mm or more, for example, when the aluminum porous body 10 is used as a current collector for an electrode of an electricity storage device, the current collector has a large active material retention amount. Can do. Moreover, when the thickness of the aluminum porous body is 10.0 mm or less, an increase in manufacturing cost and an increase in weight can be suppressed. From these viewpoints, the thickness of the aluminum porous body is more preferably 0.8 mm or more and 5 mm or less, and further preferably 1 mm or more and 3 mm or less.

The porous aluminum body 10 according to the embodiment of the present disclosure preferably has a porosity of 92% or more and 98.5% or less. When the porosity of the aluminum porous body 10 is 92% or more, the aluminum porous body 10 can be made lightweight. In addition, when the aluminum porous body 10 is used as a current collector for an electrode of an electricity storage device, the amount of the active material filled in the pores 14 can be increased. When the porosity of the aluminum porous body 10 is 98.5% or less, the aluminum porous body 10 can have sufficient strength. From these viewpoints, the porosity of the aluminum porous body 10 is more preferably 93% or more and 97.5% or less, and further preferably 94% or more and 97% or less.
The porosity of the aluminum porous body is defined by the following formula.
Porosity = (1− (mass of porous material [g] / (volume of porous material [cm ³ ] × material density [g / cm ³ ])) × 100 [%]

<Electrode>
The electrode according to the embodiment of the present disclosure uses the porous aluminum body according to the embodiment of the present disclosure as a current collector. That is, it can be used as an electrode of an electricity storage device by filling the pores of the aluminum porous body with an active material. What is necessary is just to select an active material suitably according to the kind of electrical storage device.
As described above, since the porous aluminum body according to the embodiment of the present disclosure has a large surface roughness Ra of 3 μm or more, the electrode according to the embodiment of the present disclosure is an active material filled in the pores of the aluminum porous body. The contact area between the skeleton and the skeleton is large and the utilization efficiency of the active material is excellent. Further, since the porous aluminum body according to the embodiment of the present disclosure has a compressive strength in the thickness direction as large as 1.0 MPa or more, the electrode according to the embodiment of the present disclosure applies a large pressure when filling the pores with the active material. The amount of active material filling can be increased.

<Power storage device>
An electricity storage device according to an embodiment of the present disclosure uses an aluminum porous body according to the embodiment of the present disclosure as a current collector, that is, includes an electrode according to the embodiment of the present disclosure. As described above, since the electrode according to the embodiment of the present disclosure has a large active material filling amount and is excellent in the utilization efficiency of the active material, the power storage device according to the embodiment of the present disclosure including the electrode has a storage capacity. Is a large electricity storage device.
The type of the electricity storage device is not particularly limited, and examples thereof include a lithium ion battery (including a lithium ion secondary battery), an electric double layer capacitor, and a lithium ion capacitor.

Hereinafter, a lithium ion battery including the aluminum porous body according to the embodiment of the present disclosure as a current collector will be described as an example of the electricity storage device according to the embodiment of the present disclosure.
In FIG. 7, the cross-sectional schematic diagram of an example of a lithium ion battery is shown. In the lithium ion battery, a porous aluminum body with a positive electrode active material filled in pores is disposed as a positive electrode 146 in an organic electrolyte solution 143 partitioned by a separator 142, and an electrode carrying a negative electrode active material on a current collector is provided. The negative electrode 147 is disposed. A lead wire 148 and a lead wire 149 are connected to the positive electrode 146 and the negative electrode 147, respectively, and these are all housed in a case 145.
When the porous aluminum body according to the embodiment of the present disclosure is used for a positive electrode of a lithium ion battery (including a lithium ion secondary battery), lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ ) as active materials. O ₄ ), lithium nickelate (LiNiO ₂ ), or the like may be used. The active material may be used in combination with a conductive additive and a binder.

<Method for producing porous aluminum>
The aluminum porous body according to the embodiment of the present disclosure can be manufactured by improving the manufacturing method of the aluminum porous body by a conventional plating method. In addition, the manufacturing method of the aluminum porous body by the conventional plating method is a conductive treatment process for conducting a conductive treatment on the surface of a skeleton of a resin molded body having a skeleton having a three-dimensional network structure, and a resin subjected to the conductive treatment. Production of an aluminum porous body having a plating step of obtaining a resin structure by plating aluminum on the surface of a skeleton of the molded body, and a resin removing step of removing the resin molded body from the resin structure to obtain an aluminum porous body Is the method.
Below, the manufacturing method of the aluminum porous body which improved the conventional plating method is explained in full detail.

-Conductive treatment process-
The conductive treatment step is a step of preparing a resin molded body having a skeleton having a three-dimensional network structure and imparting conductivity by conducting a conductive treatment on the surface of the skeleton of the resin molded body. For example, by forming a conductive layer so as to cover the surface of the skeleton of the resin molded body, conductivity can be imparted to the surface of the skeleton of the resin molded body. FIG. 4 shows an enlarged schematic view of a partial cross section of an example of a state in which the conductive layer 16 is formed on the surface of the skeleton of the resin molded body 15.

(Resin molding)
When producing a porous aluminum body according to an embodiment of the present disclosure, a resin molded body having a three-dimensional network structure skeleton (hereinafter, also simply referred to as “resin molded body”) is used as a base material. The resin molded body 15 has pores 14 formed by a skeleton, and further, a plurality of pores 14 are connected to form continuous ventilation holes. As the resin molding 15, for example, a resin foam, a nonwoven fabric, a felt, a woven fabric, or the like can be used, and these can be used in combination as necessary. The material of the resin molded body 15 may be any material that can be removed by heat treatment after aluminum is plated on the surface of the skeleton. In addition, the resin molded body 15 is preferably a flexible material because the skeleton is broken when the rigidity is too high particularly in the case of a sheet-like material for handling.
A resin foam is preferably used as the resin molded body 15 having a three-dimensional network structure skeleton. As the resin foam, any known or commercially available resin may be used as long as it is porous. For example, urethane foam, foamed styrene and the like can be used. Among these, urethane foam is preferable from the viewpoint of particularly high porosity. FIG. 5 shows a photograph of the urethane foam resin.

Since aluminum is electrodeposited on the surface of the skeleton of the resin molded body 15 to form a skeleton of the aluminum porous body, the porosity, average pore diameter, and thickness of the aluminum porous body are the same as the porosity and average of the resin molded body 15. It becomes substantially equal to the pore diameter and thickness. For this reason, what is necessary is just to select suitably the porosity, average pore diameter, and thickness of the resin molding 15 according to the porosity, average pore diameter, and thickness of the aluminum porous body which is a manufacturing objective. The porosity and average pore diameter of the resin molded body 15 are defined in the same manner as the porosity and average pore diameter of the aluminum porous body.

(Conductive treatment)
A method for conducting the surface of the skeleton of the resin molded body 15 is not particularly limited as long as the conductive layer 16 can be provided on the surface of the skeleton of the resin molded body 15. Examples of the material constituting the conductive layer 16 include metals such as nickel, copper, aluminum, titanium, and stainless steel, amorphous carbon such as carbon black, and carbon powder such as graphite. Among these, carbon powder is particularly preferable, and carbon black is more preferable. When the conductive layer 16 is formed using amorphous carbon or carbon powder other than metal, the conductive layer 16 is also removed in a resin removal step described later.
As specific examples of the conductive treatment, for example, when nickel, copper, aluminum, or the like is used, electroless plating treatment, sputtering treatment, or the like is preferable. In addition, when using a metal such as titanium or stainless steel, or a material such as carbon black or graphite, a mixture obtained by adding a binder to fine powder of these materials is applied to the surface of the skeleton of the resin molded body 15. The process to perform is mentioned as a preferable method.

As described above, carbon black, activated carbon, graphite or the like can be used as the carbon powder. Carbon black may be used for the purpose of making the conductivity uniform, and fine graphite powder may be used for considering the strength of the conductive layer 16. Moreover, it is preferable to mix including activated carbon. You may add the thickener generally used, for example, carboxymethylcellulose (CMC) etc., when producing a slurry. The surface of the skeleton of the resin molded body can be made conductive by applying this slurry to the skeleton of the resin molded body that has been cut into a plate shape or a strip shape by adjusting the thickness.

As the electroless plating treatment using nickel, for example, the resin molded body 15 may be immersed in a known electroless nickel plating bath such as a nickel sulfate aqueous solution containing sodium hypophosphite as a reducing agent. If necessary, before immersion in the plating bath, the resin molded body 15 may be immersed in an activation liquid containing a trace amount of palladium ions (a cleaning liquid manufactured by Kanigen Co., Ltd.).
As a sputtering process using nickel, copper, aluminum, etc., for example, after the resin molded body 15 is attached to the substrate holder, the inert gas is introduced while the holder and the target (nickel, copper, aluminum, etc.) are interrogated. By applying a DC voltage to the ionized inert gas, the ionized inert gas collides with nickel, copper, aluminum or the like, and particles of nickel, copper, aluminum or the like blown off are deposited on the surface of the skeleton of the resin molded body 15. Good. In the case of performing the sputtering treatment with aluminum, a porous aluminum body in which a different metal is not mixed in the skeleton can be produced.

The conductive layer 16 may be continuously formed so as to cover the surface of the skeleton of the resin molded body 15. The basis weight of the conductive layer 16 is not limited, and is preferably 1.0 g / m ² or more and 30 g / m ² or less, more preferably 5.0 g / m ² or more and 20 g / m ² or less. 7.0 g / m ² or more and 15 g / m ² or less is more preferable.
The basis weight of the conductive layer refers to the mass of the conductive layer in an apparent unit area of the resin molded body in which the conductive layer is formed on the surface of the skeleton.

-Plating process-
The plating process is a process of obtaining a resin structure by electrodepositing aluminum on the surface of the skeleton of the resin molded body by subjecting the resin molded body having a conductive layer formed on the surface of the skeleton to electrolytic treatment in an electrolytic solution. is there. FIG. 6 is a schematic enlarged view of a partial cross section of an example in which the aluminum film 11 is further formed on the surface of the conductive layer 16 formed on the surface of the skeleton of the resin molded body 15.

(Electrolyte)
As the electrolytic solution, a molten salt containing the following component (A) and component (B) and further containing component (C) as an additive are used.
Component (A): Aluminum halide (B) Component: One or more compounds selected from the group consisting of alkylimidazolium halides, alkylpyridinium halides, and urea compounds (C) Component: phenanthroline May contain other components as inevitable impurities. Moreover, as long as the aluminum porous body which concerns on embodiment of this indication can be manufactured, other components may be included intentionally in electrolyte solution.

The aluminum halide as the component (A) can be favorably used as long as it forms a molten salt at about 110 ° C. or less when mixed with the component (B). For example, aluminum chloride (AlCl ₃ ), aluminum bromide (AlBr ₃ ), aluminum iodide (AlI ₃ ) and the like can be mentioned. Among these, aluminum chloride is most preferable.

As the alkylimidazolium halide of the component (B), those that form a molten salt at about 110 ° C. or less when mixed with the component (A) can be used favorably.
For example, imidazolium chloride having an alkyl group (1 to 5 carbon atoms) at the 1,3 position, imidazolium chloride having an alkyl group (1 to 5 carbon atoms) at the 1,2,3 position, 1,3 position And imidazolium ioside having an alkyl group (having 1 to 5 carbon atoms).
More specifically, 1-ethyl-3-methylimidazolium chloride (EMIC), 1-butyl-3-methylimidazolium chloride (BMIC), 1-methyl-3-propylimidazolium chloride (MPIC) and the like can be mentioned. Of these, 1-ethyl-3-methylimidazolium chloride (EMIC) can be most preferably used.

As the alkylpyridinium halide of the component (B), those that form a molten salt at about 110 ° C. or less when mixed with the component (A) can be used favorably.
Examples thereof include 1-butylpyridinium chloride (BPC), 1-ethylpyridinium chloride (EPC), 1-butyl-3-methylpyridinium chloride (BMPC), etc. Among them, 1-butylpyridinium chloride is most preferable.

The urea compound of the component (B) means urea and derivatives thereof, and those that form a molten salt at about 110 ° C. or less when mixed with the component (A) can be used favorably.
For example, a compound represented by the following formula (1) can be preferably used.

However, in Formula (1), R is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group, and may be the same or different.
Of these, urea and dimethylurea can be particularly preferably used as the urea compound.

The electrolyte solution has a mixing ratio of the component (A) and the component (B) in a molar ratio of 1: 1 to 3: 1, so that the surface of the skeleton of the resin molded body An electrolytic solution (plating solution) suitable for electrodepositing aluminum is obtained.
When the molar ratio of the component (A) is less than 1 when the component (B) is 1, no aluminum electrodeposition reaction occurs. Moreover, when the molar ratio of the component (A) exceeds 3 when the component (B) is 1, aluminum chloride is precipitated in the electrolytic solution and is electrodeposited on the surface of the skeleton of the resin molded body. Incorporated into aluminum, the quality of aluminum is reduced.

The component (C) 1,10-phenanthroline is generally an additive for smoothing the surface of the aluminum film that is electrodeposited on the surface of the substrate. The amount of 1,10-phenanthroline added is preferably such that, for example, the concentration in the electrolyte is 5.0 g / L or more and 7.5 g / L or less. When the concentration of 1,10-phenanthroline in the electrolytic solution is 5.0 g / L or more, an aluminum porous body having a uniform aluminum film thickness and high compressive strength can be produced. When the concentration of 1,10-phenanthroline in the electrolytic solution is 7.5 g / L or less, the amount of 1,10-phenanthroline taken into the aluminum film is reduced, and the residual stress in the aluminum film becomes too large. Or it can suppress that the softness | flexibility of an aluminum film worsens. From these viewpoints, the concentration of 1,10-phenanthroline in the electrolytic solution is more preferably 5.5 g / L or more and 6.7 g / L or less, and more preferably 5.5 g / L or more and 6.1 g / L. More preferably, it is set to L or less.

As the component (C), 1,10-phenanthroline monohydrate and 1,10-phenanthrolinium chloride monohydrate can also be used.
When 1,10-phenanthroline monohydrate is used, the concentration in the electrolytic solution is 0.1 g / L or more and 1.0 g / L or less from the same viewpoint as described for 1,10-phenanthroline. It is preferably 0.3 g / L or more and 0.7 g / L or less, more preferably 0.3 g / L or more and 0.5 g / L or less.
Similarly, when 1,10-phenanthrolinium chloride monohydrate is used, the concentration in the electrolytic solution is preferably 0.01 g / L or more and 0.5 g / L or less, preferably 0.03 g / L. More preferably, it is L or more and 0.2 g / L or less, and further preferably 0.03 g / L or more and 0.1 g / L or less.

(Electrolytic treatment conditions)
The electrolytic treatment (molten salt electrolysis) can be performed as follows.
The resin molded body after the conductive treatment process and aluminum are arranged facing each other in the electrolytic solution, the resin molded body is connected to the cathode side of the rectifier, aluminum is connected to the anode side, and a voltage is applied between both electrodes. Apply.
At this time, when the liquid temperature of the electrolytic solution is about 45 ° C., the current is controlled by applying a voltage so that the current density is 3.0 A / dm ² or more and 6.0 A / dm ² or less. It is preferable to carry out molten salt electrolysis. By setting the current density to 3.0 A / dm ² or more, a smooth aluminum film can be formed. Further, by setting the current density to 6.0 A / dm ² or less, it is possible to suppress the occurrence of kogation in which the aluminum film formed on the surface of the skeleton of the resin molded body changes to black. From these viewpoints, the current density is more preferably 3.0 A / dm ² or more and 5.0 A / dm ² or less, and further preferably 3.5 A / dm ² or more and 4.5 A / dm ² or less. preferable.
The current density is calculated based on the apparent area of the surface of the resin molded body on which the aluminum film is formed.

-Resin removal process-
The resin removing step is a step of obtaining a porous aluminum body by removing the resin molded body by heat-treating the resin structure obtained in the plating step. When the conductive layer 16 formed on the surface of the skeleton of the resin molded body 15 is amorphous carbon or carbon powder other than metal, the conductive layer 16 also disappears by heat treatment. For example, in the example of the resin structure shown in FIG. 4, the resin molded body 15 and the conductive layer 16 disappear by heat treatment, and the aluminum film 11 remains. Thereby, the aluminum porous body 10 which has the frame | skeleton of a three-dimensional network structure is obtained (refer FIG. 1). If the conductive layer 16 of the resin structure is made of metal, the metal that has formed the conductive layer 16 diffuses into the aluminum film 11 by heat-treating the resin structure, or aluminum and It is alloyed.

When performing the resin removal step, the resin structure taken out from the electrolytic solution is first washed with pure water and then heat-treated. Conventionally, when the resin structure is washed with pure water, the electrolytic solution remaining on the surface of the skeleton of the resin structure has been sufficiently removed. On the other hand, in order to manufacture the porous aluminum body according to the embodiment of the present disclosure, the electrolytic solution is not sufficiently removed from the surface of the skeleton of the resin structure. As a result, the electrolytic solution remaining on the surface of the skeleton of the resin structure reacts with water to corrode aluminum, forming very fine irregularities on the surface of the aluminum film 11 and forming the skeleton of the resin structure. The surface roughness Ra can be increased. After the resin structure is washed with pure water, the resin molded body is removed from the resin structure by heat treatment (about 370 ° C. or more and about 660 ° C. or less) in an oxidizing atmosphere such as an air atmosphere, and the aluminum film 11 Thus, a porous aluminum body having a skeleton formed can be obtained.

In order to make the surface roughness Ra of the skeleton of the porous aluminum body 3 μm or more, the amount of the electrolytic solution remaining on the surface of the skeleton of the resin structure is 35 ml / day based on the apparent area of the resin structure. It is preferable to perform the cleaning in a state of m ² or more and 200 ml / m ² or less. The amount of the electrolyte remaining on the surface of the skeleton of the resin structure is that the thickness of the resin structure per mm.
When the resin structure is washed with pure water, the amount of electrolyte remaining on the surface of the skeleton of the resin structure is 35 ml / m ² or more, so that the surface of the aluminum film 11 is sufficiently roughened. The surface roughness Ra can be 3 μm or more. In addition, when washing with pure water, the amount of electrolyte remaining on the surface of the skeleton of the resin structure is set to 200 ml / m ² or less, so that the water that has reacted with the plating solution becomes hydrochloric acid to form the skeleton. It can suppress that the surface is corroded and the strength of the skeleton is lowered. From these viewpoints, the amount of the electrolyte remaining on the surface of the skeleton of the resin structure when washed with pure water is more preferably 40 ml / m ² or more and 150 ml / m ² or less, and 60 ml / m 2. ² or more, and more preferably 100 ml / ^{m 2} or less.

As described above, in the plating step, an electrolytic solution in which the concentration of 1,10-phenanthroline, 1,10-phenanthroline monohydrate, or 1,10-phenanthroline chloride monohydrate is a predetermined concentration or more is used. By using it, a resin structure having a uniform thickness of the aluminum film 11 can be obtained. When this resin structure is washed, the electrolyte solution remains on the surface of the skeleton as described above, so that the skeleton has a uniform film thickness and excellent strength, and the skeleton has a surface roughness Ra. A large porous aluminum body can be obtained.

In order to burn and remove the resin molded body from the resin structure by heat treatment, the resin structure is 370 ° C. or higher and 660 ° C. or lower, preferably 500 ° C. or higher and 620 ° C. or lower in an oxidizing atmosphere such as an air atmosphere. What is necessary is just to heat-process.

Hereinafter, the present disclosure will be described in more detail based on examples. However, these examples are merely examples, and the aluminum porous body of the present disclosure and the manufacturing method thereof are not limited thereto. The scope of the present disclosure is defined by the terms of the claims, and includes meanings equivalent to the terms of the claims and all changes within the scope.

[Example 1]
<Conductive treatment process>
A polyurethane sheet having a thickness of 1.0 mm was used as a resin molded body having a three-dimensional network structure. The porosity of the resin molded body was 96%, and the average pore diameter was 450 μm.
The conductive treatment was performed by immersing the polyurethane sheet in a carbon suspension and drying it to form a conductive layer on the surface of the skeleton of the polyurethane sheet. The components of the carbon suspension included 25% graphite and carbon black, and included a resin binder, a penetrating agent, and an antifoaming agent. The particle size of carbon black was 0.5 μm.

<Plating process>
(Electrolyte)
Aluminum chloride (AlCl ₃ ) is used as component (A), 1-ethyl-3-methylimidazolium chloride (EMIC) is used as component (B), and the mixing ratio of component (A) to component (B) is molar ratio. The molten salt was prepared by mixing at 2: 1. An electrolytic solution was obtained by adding 1,10-phenanthroline as a component (C) to the molten salt to a concentration of 5.0 g / L.
(Molten salt electrolysis)
In the electrolytic solution obtained above, molten salt electrolysis was performed so that the electrically conductive polyurethane sheet was the cathode and the aluminum plate having a purity of 99.99% was the anode. Thereby, aluminum was electrodeposited on the surface of the skeleton of the polyurethane sheet, and a resin structure having a three-dimensional network structure was obtained. The temperature of the electrolyte was 45 ° C., and the current density was 6.0 A / dm ² .

<Resin removal process>
The resin structure was pulled up from the electrolyte solution and washed with pure water in a state where the amount of the electrolyte solution remaining on the surface of the skeleton of the resin structure was 35 ml / m ² . As a result, a hydrolysis reaction of the electrolytic solution was generated to generate heat, and very fine irregularities could be formed on the surface of the aluminum film.
Subsequently, the polyurethane sheet and the conductive layer were removed from the resin structure by performing a heat treatment at 610 ° C. for 20 minutes in an air atmosphere. 1 could be obtained.
Aluminum porous body No. The basis weight of 1 was 140 g / m ² , and the average pore diameter was 450 μm.

[Example 2]
In the resin removal step of Example 1, the same procedure as in Example 1 was performed, except that cleaning with pure water was performed in a state where the amount of the electrolyte remaining on the surface of the skeleton of the resin structure was 40 ml / m ^2. Aluminum porous body No. 2 was obtained.

[Example 3]
In the resin removal step of Example 1, the same procedure as in Example 1 was performed, except that cleaning with pure water was performed in a state where the amount of the electrolyte remaining on the surface of the skeleton of the resin structure was 60 ml / m ^2. Aluminum porous body No. 3 was obtained.

[Example 4]
In the resin removal step of Example 1, the same procedure as in Example 1 was performed, except that cleaning with pure water was performed in a state where the amount of the electrolyte remaining on the surface of the skeleton of the resin structure was 100 ml / m ^2. Aluminum porous body No. 4 was obtained.

[Example 5]
In the resin removal step of Example 1, the same procedure as in Example 1 was performed, except that cleaning with pure water was performed in a state where the amount of the electrolyte remaining on the surface of the skeleton of the resin structure was 200 ml / m ^2. Aluminum porous body No. 5 was obtained.

[Example 6]
In the plating step of Example 3, the porous aluminum body No. 1 was prepared in the same manner as in Example 3 except that the concentration of 1,10-phenanthroline in the electrolytic solution was 7.5 g / L. 6 was obtained.

[Comparative Example 1]
In the plating step of Example 1, the concentration of 1,10-phenanthroline in the electrolytic solution was set to 0.25 g / L, and in the resin removing step, the electrolytic solution remaining on the surface of the skeleton of the resin structure was removed. Except for washing with pure water in an amount of 14 ml / m ² , the porous aluminum body No. 1 was prepared in the same manner as in Example 1. A was obtained.

[Comparative Example 2]
In the plating step of Example 1, the concentration of 1,10-phenanthroline in the electrolytic solution was set to 1.25 g / L, and in the resin removing step, the electrolytic solution remaining on the surface of the skeleton of the resin structure was removed. Except for washing with pure water in an amount of 13 ml / m ² , the porous aluminum body No. 1 was prepared in the same manner as in Example 1. B was obtained.

[Comparative Example 3]
In the resin removal step of Example 1, the same procedure as in Example 1 was performed, except that cleaning with pure water was performed in a state where the amount of the electrolyte remaining on the surface of the skeleton of the resin structure was 16 ml / m ^2. Aluminum porous body No. C was obtained.

[Comparative Example 4]
In the resin removal step of Example 1, the same procedure as in Example 1 was performed, except that cleaning with pure water was performed in a state where the amount of the electrolyte remaining on the surface of the skeleton of the resin structure was 30 ml / m ^2. Aluminum porous body No. D was obtained.

-Evaluation-
The aluminum porous body No. obtained as described above was used. 1 to No. 6 and aluminum porous body no. A to No. For D, the surface roughness Ra of the skeleton and the compressive strength in the thickness direction were measured as follows.

(Surface roughness Ra of the skeleton of the aluminum porous body)
Aluminum porous body No. Five areas of 25 μm × 25 μm were selected on the surface of the aluminum film 11 constituting one pore portion 14, and the arithmetic average roughness was measured with a laser type surface roughness meter. A value obtained by averaging the arithmetic average roughness in each area is shown in Table 1 as the surface roughness Ra.
Aluminum porous body No. 2 to No. 6 and aluminum porous body no. A to No. For D, the surface roughness Ra was measured in the same manner.

(Compressive strength in the thickness direction of the porous aluminum body)
Aluminum porous body No. A test piece was prepared by punching 1 into a circle having a diameter of 20 mm. A load was applied in the thickness direction of the test piece using a compression tester, and the load necessary to reduce the thickness of the test piece by 5% was measured as the compressive strength. The results are shown in Table 1.
Aluminum porous body No. 2 to No. 6 and aluminum porous body no. A to No. The compressive strength was similarly measured for D.

As shown in Table 1, porous aluminum body No. 1 according to the embodiment of the present disclosure. 1 to No. In No. 6, the surface roughness Ra of the skeleton was 3 μm or more, and the compressive strength in the thickness direction was 1.0 MPa or more.
On the other hand, the aluminum porous body No. A and No. B has a large surface roughness but a low compressive strength. C and No. D had high compressive strength but low surface roughness.
Also, aluminum porous body No. The photograph which observed the cross section of 2 with the scanning electron microscope is shown in FIG. 8, and the enlarged view of the part shown with the white frame in FIG. 8 is shown in FIG. According to an embodiment of the present disclosure, an aluminum porous body No. 2 confirmed that the surface of the skeleton was very rough as compared with the conventional porous aluminum body.

DESCRIPTION OF SYMBOLS 10 Aluminum porous body 11 Aluminum film 12 Frame | skeleton 13 Inside of frame | skeleton 14 Porous part 15 Resin molding 16 Conductive layer 142 Separator 143 Organic electrolyte 145 Case 146 Positive electrode 147 Negative electrode 148 Lead wire 149 Lead wire

Claims (7)

A sheet-like aluminum porous body having a three-dimensional network structure skeleton,
The surface roughness Ra of the skeleton is 3 μm or more,
The compressive strength in the thickness direction of the aluminum porous body is 1.0 MPa or more,
Aluminum porous body. Basis weight per a thickness of 1 mm, 50 g / ^{m 2} or more and 200 g / ^{m 2} or less, an aluminum porous body according to claim 1. The aluminum porous body according to claim 1 or 2, wherein the average pore diameter is 300 µm or more and 3500 µm or less. The aluminum porous body according to any one of claims 1 to 3, wherein the thickness is 0.6 mm or more and 10.0 mm or less. An electrode comprising the porous aluminum body according to any one of claims 1 to 4 as a current collector. An electricity storage device comprising the aluminum porous body according to any one of claims 1 to 4 as a current collector. A method for producing a porous aluminum body, comprising:
A conductive treatment step of forming a conductive layer on the surface of the skeleton of the resin molded body having a skeleton of a three-dimensional network structure;
A plating step of obtaining a resin structure by electrodepositing aluminum on the surface of the skeleton of the resin molded body;
A resin removal step of removing the resin molded body and the conductive layer from the resin structure to obtain an aluminum porous body;
Including
The electrolytic solution used in the plating step contains 5.0 g / L or more and 7.5 g / L or less of 1,10-phenanthroline as an additive,
In the resin removal step, the amount of the electrolyte remaining on the surface of the skeleton of the resin structure is 35 ml / m ² or more and 200 ml / m ² or less based on the apparent area of the resin structure. Cleaning in a certain state,
Basis weight per a thickness of 1 mm, 50 g / ^{m 2} or more to obtain a porous aluminum body is 200 g / ^{m 2} or less,
A method for producing a porous aluminum body.

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