JP2014234530A - Aluminum porous body, collector, electrode, electrochemical device, and production method of aluminum porous body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum porous body or the like having a three-dimensional network structure having a small moisture adsorption amount, which can be used for an electrode material or the like of an electrochemical device using a non-aqueous electrolyte, such as a lithium ion battery and a capacitor.SOLUTION: The aluminum porous body has a three-dimensional network structure having a hollow skeleton. The aluminum porous body has a surface porous layer having a thickness of 1.0 μm or less in a hollow part of the skeleton, and has a moisture adsorption amount of 30 mg/mor less.

Description

  The present invention relates to an aluminum porous body having a three-dimensional network structure, a current collector, an electrode, an electrochemical device, and a method for producing the aluminum porous body.

  Metal porous bodies having a three-dimensional network structure are used in various fields such as various filters, catalyst carriers, and battery electrodes. For example, Celmet (manufactured by Sumitomo Electric Industries, Ltd .: registered trademark) made of a porous nickel body having a three-dimensional network structure (hereinafter referred to as “nickel porous body”) is an electrode material for batteries such as nickel metal hydride batteries and nickel cadmium batteries. It is used as Celmet is a metal porous body having continuous air holes, and has a feature of high porosity (90% or more) compared to other porous bodies such as a metal nonwoven fabric.

  Such a nickel porous body is obtained by forming a nickel layer on the surface of a porous resin skeleton having continuous vents such as foamed urethane, then heat-treating it to decompose the foamed resin molded body, and further reducing the nickel. It is done. The formation of the nickel layer is performed by depositing nickel by electroplating after applying carbon powder or the like to the surface of the skeleton of the foamed resin molded body and conducting a conductive treatment.

In addition to nickel, aluminum also has excellent characteristics such as conductivity, corrosion resistance, and light weight. In battery applications, for example, a positive electrode of a lithium ion battery is coated with an active material such as lithium cobalt oxide on the surface of an aluminum foil. Is used.
In order to improve the capacity of the positive electrode using aluminum, an aluminum porous body having a three-dimensional network structure with a large aluminum surface area (hereinafter referred to as “aluminum porous body”) is used. It is also conceivable to fill the active material. This is because by using the porous aluminum body, the active material can be retained even when the electrode is thickened, and the active material utilization rate per unit area is improved.

As a method for producing a porous aluminum body, Japanese Patent No. 3413666 (Patent Document 1) discloses that a two-dimensional net-like plastic substrate having an internal communication space is subjected to an aluminum vapor deposition process by an arc ion plating method to be 2 to 20 μm. A method for forming a metallic aluminum layer is described.
According to this method, it is said that an aluminum porous body having a thickness of 2 to 20 μm can be obtained, but it is difficult to manufacture in a large area because of the vapor phase method, and depending on the thickness and porosity of the substrate, It is difficult to form a uniform layer. In addition, there are problems such as a slow formation rate of the aluminum layer and an increase in manufacturing cost due to expensive equipment. Further, when a thick film is formed, there is a risk that the film may crack or aluminum may fall off.

Japanese Patent Application Laid-Open No. 08-170126 (Patent Document 2) discloses a film made of a metal (such as copper) that forms a eutectic alloy below the melting point of aluminum on the skeleton of a foamed resin molding having a three-dimensional network structure. After forming, an aluminum paste is applied, and heat treatment is performed at a temperature of 550 ° C. or higher and 750 ° C. or lower in a non-oxidizing atmosphere to eliminate the organic component (foamed resin) and to sinter the aluminum powder. Is described.
However, according to this method, a layer that forms a eutectic alloy with aluminum is formed, and a high-purity aluminum layer cannot be formed.

  As another method, there is a method of performing aluminum plating on a foamed resin molded body having a three-dimensional network structure. JP 2012-007233 A (Patent Document 3) discloses a porous aluminum body obtained by this plating method. The invention is described for a capacitor using as an electrode. According to the method described in Patent Document 3, it is possible to uniformly plate high-purity aluminum on a porous resin molded body having a three-dimensional network structure, and to produce a high-quality aluminum porous body Can do.

  By the way, an electrochemical device using a non-aqueous electrolyte such as the above-described lithium ion battery or capacitor needs to be manufactured in an environment in which moisture is sufficiently removed, and a current collector used as an electrode needs to be sufficiently dried. There is. Since the porous aluminum body used in the capacitor described in Patent Document 3 adsorbs a relatively large amount of moisture on the surface of the skeleton, it is sufficiently dried to be used as an electrode for an electrochemical device as described above. It is necessary to perform a process.

Japanese Patent No. 3413662 JP 08-170126 A JP 2012-007233 A

  In view of the above problems, an object of the present invention is to provide a porous aluminum body having a three-dimensional network structure with a small amount of moisture adsorption.

As a result of intensive investigations to solve the above-mentioned problems, the present inventors have found that an aluminum porous body having a three-dimensional network structure manufactured by a conventional plating method has a porous porous surface on the surface of the hollow portion of the skeleton. A layer was formed, and it was found that this porous layer adsorbs moisture.
Therefore, as a result of further studies, the inventors have improved the conventional method for producing an aluminum porous body by plating, so that the surface of the hollow portion of the skeleton is smooth and the amount of moisture adsorption is high. The inventors have found that a small number of aluminum porous bodies can be produced and completed the present invention.

That is, the present invention is (1) an aluminum porous body having a three-dimensional network structure with a hollow skeleton, wherein the porous aluminum body has a porous layer thickness of 1.0 μm or less in the hollow portion of the skeleton, And the aluminum porous body whose moisture adsorption amount of the said aluminum porous body is 30 mg / m < ² > or less.

  According to the present invention, it is possible to provide a porous aluminum body having a three-dimensional network structure with a small amount of moisture adsorption.

It is the electron micrograph which observed the frame | skeleton cross section of the aluminum porous body of an Example. It is the electron micrograph which observed the frame | skeleton cross section of the aluminum porous body of a comparative example. It is a graph showing the moisture adsorption amount of the aluminum porous body of an Example and a comparative example. It is a schematic diagram which shows the structural example which applied the aluminum porous body to the lithium battery. It is a schematic diagram which shows the structural example which applied the aluminum porous body to the capacitor. It is a schematic diagram which shows the structural example which applied the aluminum porous body to the lithium ion capacitor. It is a cross-sectional schematic diagram which shows the structural example which applied the aluminum porous body to the molten salt battery.

First, the contents of the embodiment of the present invention will be listed and described.
(1) The aluminum porous body according to the present invention is an aluminum porous body having a three-dimensional network structure with a hollow skeleton, and the porous aluminum body has a porous layer thickness of 1.0 μm in the hollow portion of the skeleton. The aluminum porous body has a water adsorption amount of 30 mg / m ² or less.
When the aluminum porous body has a three-dimensional network structure, for example, when the aluminum porous body is used for an electrode of an electrochemical device, the active material retention rate is increased by increasing the amount of active material retained. Therefore, it is possible to manufacture an electrode having a large capacity.
Further, when the thickness of the porous layer on the surface of the hollow portion of the skeleton is 1.0 μm or less, it becomes difficult for moisture to be adsorbed to the porous layer, and the moisture adsorption amount of the aluminum porous body can be reduced. From this viewpoint, the thickness of the porous layer is preferably 0.8 μm or less, and more preferably 0.5 μm or less.

Further, since the moisture adsorption amount of the aluminum porous body is 30 mg / m ² or less, for example, the aluminum porous body is removed in an environment where moisture is removed like a battery using a nonaqueous electrolyte or a capacitor electrode. When used, it is possible to reduce the burden on the moisture removal and removal process.
From the above viewpoint, the moisture adsorption amount of the aluminum porous body is preferably as small as possible, more preferably 12 mg / m ² or less, further preferably 8 mg / m ² or less, and 5 mg / m ² or less. Is most preferred.
In the present invention, the moisture adsorption amount means the moisture amount per apparent area of the porous aluminum body after being exposed to an atmosphere having a dew point temperature of −20 ° C. for 24 hours.

(2) Moreover, the manufacturing method of the aluminum porous body which concerns on this invention removes the said base material, the process of forming an aluminum film by molten salt electroplating on the surface of the resin-made base materials which have a three-dimensional network structure A method for producing a porous aluminum body, comprising: a step of treating the porous aluminum body having a hollow three-dimensional network structure formed by removing the base material with an acid or a base. is there.
According to the method for producing a porous aluminum body described in (2) above, an aluminum porous body having a three-dimensional network structure in which the thickness of the porous layer on the surface of the hollow portion of the skeleton can be reduced and the amount of moisture adsorption is small. Can be manufactured.

(3) Moreover, it is preferable that the said base material is electrically conductive-processed by carbon application | coating.
Since the base material is made of resin, in order to subject aluminum to molten salt electroplating, it is necessary to make the surface of the base material conductive so that the surface has conductivity. The method of this conductive treatment is not particularly limited, but simple and uniform conduction can be achieved by adopting the method by carbon coating.
However, in the conventional method for producing a porous aluminum body by a plating method, there is a problem in that a porous layer is formed in the hollow portion of the skeleton of the porous aluminum body when the surface of the substrate is subjected to a conductive treatment by carbon coating. On the other hand, the method for producing a porous aluminum body of the present invention includes the step of treating the porous aluminum body with an acid or a base as described above, so that the thickness of the porous layer on the surface of the hollow portion of the skeleton is small. A thin aluminum porous body can be obtained.

(4) In the method for producing the porous aluminum body, the amount of the plating solution adhered to the aluminum film is 0.1 mL / m ² or more and 30 mL / m ² or less before the step of removing the substrate. It is preferable to have a step of draining liquid.
(5) It is preferable that the manufacturing method of the said aluminum porous body has the process of removing the plating solution adhering to the said aluminum film with an organic solvent before the process of removing the said base material.
(6) It is preferable that the manufacturing method of the said aluminum porous body has the process of supplying the air | atmosphere whose dew point temperature is -50 degreeC or more and -30 degrees C or less to the said aluminum film before the process of removing the said base material. .
(7) Preferably, in the method for producing the porous aluminum body, in the step of removing the substrate, heat treatment is performed at a temperature of 370 ° C. or higher and lower than the melting point of aluminum in an atmosphere having a dew point temperature of 0 ° C. or lower.

  Any of the methods for producing a porous aluminum body according to the above (4) to (7) can prevent fine irregularities from being formed on the outer surface of the skeleton, and can be formed on the surface of the hollow portion of the skeleton. Combined with the thin porous layer, an aluminum porous body with less moisture adsorption can be produced.

(8) Moreover, the collector which is embodiment of this invention is a collector for electrochemical devices which consists of an aluminum porous body of this invention as described in said (1).
By using the aluminum porous body of the present invention as a current collector for an electrochemical device, an electrochemical device having a large capacity can be produced. Moreover, since the aluminum porous body of the present invention has a small amount of moisture adsorption, when used in an electrochemical device using a non-aqueous electrolyte, the burden on the electrode drying step can be reduced.

(9) Moreover, the electrode which is embodiment of this invention is an electrode for electrochemical devices which has an active material in the pore part of the aluminum porous body of this invention as described in said (1).
By filling the pores of the aluminum porous body with an active material, an electrode having a large capacity can be obtained. Moreover, when using it for the electrochemical device using a nonaqueous electrolyte, the burden concerning the drying process of an electrode can be reduced.

(10) Moreover, the electrochemical device which is embodiment of this invention is an electrochemical device using the electrode of this invention as described in said (9).
Since the electrochemical device of the present invention uses the electrode of the present invention having a high utilization rate of the active material per unit volume, the capacity can be increased. In addition, in the case of an electrochemical device using a non-aqueous electrolyte, the manufacturing cost can be reduced because the burden required for the electrode drying step is reduced.

[Details of the embodiment of the present invention]
The specific example of the aluminum porous body which concerns on embodiment of this invention is demonstrated below. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included.

<Porous aluminum body>
The porous aluminum body according to the present invention is a porous aluminum body having a three-dimensional network structure with a hollow skeleton, wherein the thickness of the porous layer of the hollow portion of the skeleton is 1.0 μm or less, and moisture adsorption The amount is 30 mg / m ² or less.
As described later, the aluminum porous body of the present invention can be produced by a method in which aluminum is molten salt electroplated on the surface of a resin porous body having a three-dimensional network structure. The skeleton of the porous aluminum body obtained by the plating method has a hollow structure by removing the resin. For this reason, the strength of the skeleton is relatively weak. For example, when the porous aluminum body is used as an electrode for an electrochemical device, deformation occurs when the pores are filled with an active material and the thickness is adjusted. Easy to adjust and can be adjusted easily.

In the porous aluminum body of the present invention, the thickness of the porous layer on the surface of the hollow portion of the skeleton is very thin.
When an aluminum porous body is produced by a conventional plating method, especially when a resin substrate surface is subjected to a conductive treatment by carbon coating, a porous layer is formed on the surface of the hollow portion of the skeleton of the aluminum porous body. This porous layer had adsorbed moisture.
On the other hand, the porous aluminum body obtained by the method for producing an aluminum porous body of the present invention, which will be described later, has a porous layer formed on the surface of the hollow portion of the skeleton and the moisture is not easily absorbed. Compared with the aluminum porous body, the water adsorption amount is remarkably reduced.

<Method for producing porous aluminum>
As described above, the method for producing a porous aluminum body according to the present invention includes a step of forming an aluminum film on the surface of a resin base material having a three-dimensional network structure by molten salt electroplating, and the base material is removed. A method for producing an aluminum porous body, comprising: a step; and a step of treating an aluminum porous body having a hollow three-dimensional network structure formed by removing the substrate with an acid or a base.
The porous aluminum body obtained by the conventional molten salt electroplating method has a porous layer formed on the surface of the hollow portion of the skeleton, but the method for producing an aluminum porous body according to the present invention uses an acid or base as the aluminum porous body. Since it has the process to process, the aluminum porous body from which the porous layer was removed from the surface of the hollow part of frame | skeleton can be obtained.
Hereinafter, the manufacturing method of the aluminum porous body which concerns on this invention is demonstrated in detail.

(Preparation of resin molding having a three-dimensional network structure)
First, a resin molded body having a three-dimensional network structure and communication holes is prepared. Any resin can be selected as the material of the resin molded body. Examples of the material include foamed resin moldings such as polyurethane, melamine, polypropylene, and polyethylene. Although described as a foamed resin molded body, a resin molded body having an arbitrary shape can be selected as long as it has continuous pores (communication holes). For example, what has a shape like a nonwoven fabric entangled with a fibrous resin can be used instead of the foamed resin molded body.

  Foamed urethane and foamed melamine can be preferably used as a foamed resin molded article because they have high porosity, have pore connectivity and are excellent in thermal decomposability. Foamed urethane is preferable in terms of uniformity of pores, availability, and the like, and in addition, a product having a small pore diameter can be obtained.

  Resin moldings often have residues such as foaming agents and unreacted monomers in the foam production process, and it is preferable to perform a cleaning treatment for the subsequent steps. Since the resin molded body has a three-dimensional network structure as a skeleton, continuous pores are formed as a whole. The urethane skeleton has a substantially triangular shape in a cross section perpendicular to the extending direction.

The foamed resin molded article preferably has a porosity of 80% to 98% and a pore diameter of 50 μm to 500 μm.
The porosity is defined by the following equation.
Porosity = (1− (weight of porous material [g] / (volume of porous material [cm ³ ] × material density))) × 100 [%]
The pore diameter is an average of the average pore diameter = 25.4 mm / cell count by enlarging the surface of the resin molded body with a micrograph and counting the number of pores per inch (25.4 mm) as the number of cells. Find the value.

(Electrically conductive resin molding surface)
In order to electroplat aluminum on the surface of the resin molded body, the surface of the resin molded body needs to be electrically conductive in advance. There is no restriction | limiting in particular as long as it is a process which can provide the layer which has electroconductivity on the surface of a resin molding as a conductive process. For example, electroless plating of a conductive metal such as nickel, vapor deposition and sputtering of aluminum or the like, or a method of applying a conductive paint containing conductive particles such as carbon can be given.

  As an example of the conductive treatment, a method of conducting the conductive treatment by sputtering of aluminum and a method of conducting the conductive treatment of the surface of the resin molded body using carbon powder as conductive particles will be described below.

-Carbon coating-
First, a carbon paint as a conductive paint is prepared. The suspension as the conductive paint preferably contains carbon particles, a binder, a dispersant and a dispersion medium. In order to uniformly apply the conductive particles, the suspension needs to maintain a uniform suspension state. For this reason, it is preferable that the suspension is maintained at 20 ° C to 40 ° C. The reason is that when the temperature of the suspension is lower than 20 ° C., the uniform suspension state is lost, and only the binder is concentrated on the surface of the skeleton forming the network structure of the porous resin body to form a layer. Because there are cases. In this case, the applied carbon particle layer is easy to peel off, and it is difficult to form a metal plating that is firmly adhered. On the other hand, when the temperature of the suspension exceeds 40 ° C., the amount of evaporation of the dispersant is large, and the suspension is concentrated as the coating treatment time elapses, and the amount of carbon applied tends to fluctuate.
Moreover, it is preferable that the particle size of carbon particle is 0.01-5 micrometers, More preferably, it is 0.01-2 micrometers. When the particle size is large, it becomes a factor that clogs the cells of the resin molded body or inhibits smooth plating, and when it is too small, it is difficult to ensure sufficient conductivity.
The application of the carbon particles to the resin molded body can be performed by immersing the target resin molded body in the suspension and performing squeezing and drying.

(Formation of aluminum film on the surface of resin molding)
As a method for forming an aluminum film on the surface of the resin molded body, a plating method using a molten salt bath is employed.
-Molten salt plating-
Electrolytic plating is performed in a molten salt to form an aluminum film on the surface of the resin molded body.
By performing aluminum plating in a molten salt bath, a thick aluminum film can be uniformly formed on the surface of a complicated skeleton structure, particularly a resin molded body having a three-dimensional network structure. A direct current is applied in a molten salt using a resin molded body having a conductive surface as a cathode and aluminum as an anode.
As the molten salt, an organic molten salt that is a eutectic salt of an organic halide and an aluminum halide, or an inorganic molten salt that is a eutectic salt of an alkali metal halide and an aluminum halide can be used. When an organic molten salt bath that melts at a relatively low temperature is used, electrolytic plating can be performed without decomposing the resin molded body as a base material. As the organic halide, imidazolium salt, pyridinium salt and the like can be used. Specifically, 1-ethyl-3-methylimidazolium chloride (EMIC) and butylpyridinium chloride (BPC) are preferable.
Since the molten salt deteriorates when moisture or oxygen is mixed in the molten salt, the plating is preferably performed in an atmosphere of an inert gas such as nitrogen or argon and in a sealed environment.

As the molten salt bath, a molten salt bath containing nitrogen is preferable, and among them, an imidazolium salt bath is preferably used. When a salt that melts at a high temperature is used as the molten salt, the resin dissolves or decomposes in the molten salt faster than the growth of the plating film, and the plating film cannot be formed on the surface of the resin molded body. The imidazolium salt bath can be used without affecting the resin even at a relatively low temperature. As the imidazolium salt, a salt containing an imidazolium cation having an alkyl group at the 1,3-position is preferably used. In particular, an aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl ₃ -EMIC) -based molten salt is used. It is most preferably used because it is highly stable and hardly decomposes. Plating onto foamed urethane resin or foamed melamine resin is possible, and the temperature of the molten salt bath is 10 ° C to 100 ° C, preferably 25 ° C to 45 ° C. The lower the temperature, the narrower the current density range that can be plated, and the more difficult it is to plate on the entire surface of the resin molded body. At a high temperature exceeding 100 ° C., a problem that the shape of the resin molded body serving as the base material is impaired tends to occur. Through the above steps, an aluminum-resin structure having a resin molded body as a skeleton core is obtained.

(Removal of resin base material)
The method for removing the resin base material from the resin structure obtained as described above is not particularly limited. For example, the heat treatment is performed by heating to 370 ° C. or higher and lower than the melting point of aluminum in a nitrogen atmosphere or the air. It can be done by doing. As a result, the resin is burned out, and an aluminum porous body having a hollow skeleton is obtained. In the step of removing the substrate, the dew point temperature of the atmosphere is preferably 0 ° C. or lower.

(Treatment with acid or base)
The method for producing a porous aluminum body according to the present invention includes a step of treating the porous aluminum body obtained as described above with an acid or a base. By treating the porous aluminum body with an acid or a base, the porous layer formed on the surface of the hollow portion of the skeleton can be removed, and an aluminum porous body in which moisture is hardly adsorbed on the surface of the hollow portion of the skeleton can be obtained. .

  The method for treating the aluminum porous body with an acid or a base is not particularly limited, and the aluminum porous body may be simply immersed in an acid or a base. When the aluminum porous body is immersed in an acidic or basic solution, the skeleton of the aluminum porous body is hollow, so that the acidic or basic solution is sucked into the skeleton by capillary action. As a result, the surface of the hollow portion of the skeleton of the porous aluminum body comes into contact with the acid or base, and the porous layer on the surface of the hollow portion is removed.

  As described above, the porous aluminum body may be simply immersed in an acid or a base, but the porous layer can be removed more efficiently by stirring an acidic or basic solution. The stirring method is not particularly limited, and may be performed using a magnetic stirrer or the like, or may be performed by generating ultrasonic waves. In the case of stirring by ultrasonic waves, it is said that ultrasonic waves having a frequency of about 37 kHz are generated in an acidic or basic solution.

The acid or base may be any acid or base that can dissolve aluminum. For example, hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄ ), sodium hydroxide (NaOH), dilute nitric acid (HNO ₃ ) Etc. can be used.

  The concentration or treatment time of the acid or base used in the treatment with the acid or base varies depending on the treatment conditions such as the type of acid or base, the presence or absence of stirring, etc., but may be appropriately adjusted to an appropriate range for removing the porous layer. . For example, when hydrochloric acid is used, the porous aluminum body may be immersed for about 5 minutes if the concentration is about 12% by mass and stirring is performed by ultrasonic irradiation with a frequency of about 37 kHz.

  Moreover, it is preferable to hydrophilize the porous aluminum body with a surfactant before the treatment with an acid or a base. Thereby, the wettability with respect to the acidic or basic aqueous solution of an aluminum porous body improves, and it becomes possible to process efficiently. The surfactant is not particularly limited, and for example, sodium stearate, sodium alkylbenzene sulfonate, or the like can be used. In addition, examples of the alkyl group of the sodium alkylbenzenesulfonate include a methyl group and an ethyl group.

(Cleaning of porous aluminum)
As described above, the porous aluminum body is treated with an acid or a base to smooth the surface of the hollow portion of the skeleton, then washed with water, and then sufficiently dried to obtain the porous aluminum body of the present invention. It is done.

As described above, the thickness of the porous layer on the surface of the hollow portion of the skeleton is thin by the method for producing a porous aluminum body of the present invention including the step of treating the porous aluminum body after removing the substrate with an acid or a base. An aluminum porous body can be obtained.
By the way, as a result of intensive investigations to further reduce the moisture adsorption amount of the aluminum porous body, the present inventors have formed fine irregularities on the surface of the skeleton of the aluminum porous body obtained by the conventional plating method. It has been found that the micropores are hygroscopic. As a result of more detailed studies, it was found that the micropores formed on the surface of the skeleton of the aluminum porous body are γ-alumina generated by the dehydration reaction of boehmite. This γ-alumina is also used as a hygroscopic agent and has been studied for its hygroscopic properties (for example, “Kazuo Kawamura, Harumi Endo,“ Hygroscopic Properties of Boehmite and Anhydrous Alumina ”, Journal of Ceramic Society of Japan 107 [4] pp 335-338 (1998) "," Lee Haiyong, Sadafumi Isshiki, "On the Transformation of γ-Alumina", Production Research, Vol. 11, No. 2, pp. 25-29, 1959 ").

Therefore, the present inventors have further investigated a method for preventing fine irregularities due to γ-alumina from occurring on the surface of the skeleton of the porous aluminum body. As a result, it has been found that there is room for improvement in a conventional method for producing a porous aluminum body having a three-dimensional network structure by a plating method (for example, JP 2012-007233 A).
That is, when heat treatment is performed when removing urethane from the resin structure, the removal temperature of urethane is usually 500 to 660 ° C. Therefore, if moisture is contained in the oxide film on the surface of the aluminum film, dehydration is performed. As a result, nano-order micropores are formed on the surface. For this reason, it is only necessary that boehmite is not formed on the surface of the aluminum film.

By the way, since neither water nor oxygen is present in a plating solution such as a molten salt such as 1-ethyl-3-methylimidazolium chloride and aluminum chloride, an aluminum film formed by molten salt electroplating is an oxide film. It does not have aluminum. Therefore, the surface state can be variously changed by the treatment after plating.
For example, when the resin structure on which the aluminum film is formed is washed with pure water immediately after being taken out of the plating solution, an aluminum oxide film containing water is formed on the outermost surface of the plating film. In addition, if the resin structure is washed with an organic solvent such as ethanol or xylene immediately after being taken out of the plating solution and exposed to the atmosphere, an oxide film containing almost no water is formed on the surface of the plating film. The Further, by blowing dry air having a low dew point immediately after the resin structure is taken out of the plating solution, an oxide film can be formed on the surface of the plating film before the cleaning treatment.

From the above, in order to produce an aluminum porous body in which fine irregularities are not formed on the surface of the skeleton and the amount of moisture adsorption is smaller, for example, the following is preferable.
The γ-alumina formed on the surface of the skeleton of the aluminum porous body is partially removed by the step of treating the aluminum porous body with an acid or a base. More preferably, no γ-alumina is formed.

-Treatment of plating solution adhering to resin structure-
The resin structure obtained by subjecting the resin base surface to molten salt electroplating on the surface of the resin has a plating solution attached to the surface. Therefore, the plating solution is removed by washing with water, followed by heat treatment. . At this time, if the washing process is performed with a large amount of plating solution adhering to the surface of the resin structure, the plating solution and water react to generate heat, and the aluminum and water react on the surface of the aluminum film, resulting in boehmite. Is formed. Then, when the resin is subsequently removed, it is considered that the boehmite is transformed into γ-alumina by being exposed to a high temperature of 500 ° C. or more, and fine irregularities are formed on the skeleton surface.

For this reason, before the resin structure is washed with water, it is preferable to remove the liquid so that the amount of the plating solution adhering to the aluminum film is 0.1 mL / m ² or more and 20 mL / m ² or less. From the above viewpoint, the amount of the plating solution adhering to the aluminum film is preferably smaller, more preferably 0.1 mL / m ² or more and 10 mL / m ² or less, 0.1 mL / m ² or more, 3 mL / More preferably, it is m ² or less.
The means for draining the plating solution is not particularly limited, and can be performed, for example, by spraying nitrogen gas, argon gas, dry air (dew point −50 ° C. or higher, −30 ° C. or lower) to the resin structure. .

Moreover, it is also preferable to remove the plating solution adhering to the aluminum film with an organic solvent before washing the resin structure with water. Thereby, the plating solution can be removed without causing the aluminum film and water to react. Then, by exposing the resin structure to the atmosphere thereafter, an oxide film containing almost no water can be formed on the surface of the aluminum film so that γ-alumina is not formed. As the organic solvent, for example, fluorinated alkenes such as ethanol, xylene, toluene and 2,3,3,4,4,5,5-heptafluoro-1-pentene can be preferably used.
In addition, when the plating solution is removed with an organic solvent, it is preferable to subsequently perform a water washing treatment to remove the organic solvent.

-Blowing dry air to the resin structure-
It is also effective to blow dry air having a low dew point immediately after the resin structure having an aluminum film formed on the substrate surface is taken out of the plating solution. Thereby, it is possible to prevent the formation of γ-alumina by forming an oxide film on the surface of the aluminum film before the water washing treatment. As the dry air having a low dew point, for example, dry air having a dew point temperature of about −50 ° C. to −30 ° C. can be used.

-Removal of resin base material-
As described above, the resin base material can be removed by performing the heat treatment for heating the resin structure to 370 ° C. or higher. However, when this step is performed in an atmosphere with a high moisture content and a high dew point, aluminum is obtained. There is a possibility that boehmite is formed by reacting with water and further transformed into γ-alumina to form fine irregularities on the skeleton surface.
For this reason, it is preferable to remove the substrate by heating the resin to 370 ° C. or higher and lower than the melting point of aluminum in an atmosphere having a dew point temperature of 0 ° C. or lower. The dew point temperature of the atmosphere is more preferably −5 ° C. or lower, and further preferably −10 ° C. or lower. In addition, since the dew point temperature at the time of removing the said base material can fully suppress reaction with the water | moisture content in the atmosphere and aluminum, about 30 degreeC, what is necessary is just to perform the said dew point temperature above -30 degreeC. The heating temperature is more preferably 500 ° C. or more and 660 ° C. or less, and further preferably 580 ° C. or more and 630 ° C. or less.

<Current collector, electrode, electrochemical device>
The porous aluminum body of the present invention can be used as a current collector for an electrochemical device, and can be used as an electrode for an electrochemical device by filling the pores with an active material. Although it is not particularly limited as an electrochemical device, as described above, the aluminum porous body of the present invention has a small amount of moisture adsorption. Therefore, when it is used for an electrochemical device using a non-aqueous electrolyte, it imposes a burden on the drying process. Can be reduced. For example, in order to sufficiently dry an aluminum porous body produced by a conventional plating method, a heat treatment of 15 hours or less at 150 ° C. and 5 Torr was required, but the aluminum porous body of the present invention was 150 ° C. and 5 Torr. The following heat treatment can be performed for 2 hours or less.
Below, an example of the electrochemical device which can utilize preferably the aluminum porous body of this invention is demonstrated.

(Lithium battery)
A lithium battery will be described as an example of an electrochemical device using the porous aluminum body of the present invention. For example, when used for a positive electrode of a lithium battery (including a lithium ion secondary battery), lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), and lithium nickelate (LiNiO ₂ ) are used as active materials. Etc. The active material is used in combination with a conductive additive and a binder.

  As a conventional positive electrode material for a lithium battery, an electrode in which an active material is applied to the surface of an aluminum foil is used. Lithium batteries have higher capacities than nickel metal hydride batteries and capacitors, but there is a need for higher capacities for automobile applications, etc., and in order to improve battery capacity per unit area, the thickness of the active material coating must be increased. In order to use the active material effectively, it is necessary that the aluminum foil as the current collector and the active material are in electrical contact with each other. It is used.

In contrast, the porous aluminum body of the present invention has a high porosity and a large surface area per unit area. Therefore, since the contact area between the current collector and the active material is increased, the active material can be used effectively, the capacity of the battery can be improved, and the mixing amount of the conductive additive can be reduced. In the lithium battery, the above positive electrode material is used as a positive electrode, and a copper or nickel foil, a punching metal, a porous body, or the like is used as a current collector for the negative electrode. Graphite, lithium titanate (Li ₄ Ti ₅ O ₁₂ ), Sn An alloy system such as Si or Si, or a negative electrode active material such as lithium metal is used. A negative electrode active material is also used in combination with a conductive additive and a binder.

  Since such a lithium battery can improve capacity even with a small electrode area, the energy density of the battery can be made higher than that of a lithium battery using a conventional aluminum foil. In addition, the effect on the secondary battery has been mainly described above. However, the effect of increasing the contact area when the porous aluminum body is filled with the active material is the same as that of the secondary battery in the primary battery. Can be improved.

-Lithium battery configuration-
The electrolyte used for the lithium battery includes a non-aqueous electrolyte and a solid electrolyte.
FIG. 4 is a longitudinal sectional view of an all-solid lithium battery using a solid electrolyte. The all solid lithium battery 60 includes a positive electrode 61, a negative electrode 62, and a solid electrolyte layer (SE layer) 63 disposed between both electrodes. The positive electrode 61 includes a positive electrode layer (positive electrode body) 64 and a positive electrode current collector 65, and the negative electrode 62 includes a negative electrode layer 66 and a negative electrode current collector 67.
In addition to the solid electrolyte, a non-aqueous electrolyte described later is used as the electrolyte. In this case, a separator (porous polymer film, nonwoven fabric, paper, etc.) is disposed between both electrodes, and the non-aqueous electrolyte is impregnated in both electrodes and the separator.

-Active material filled in aluminum porous body-
When an aluminum porous body is used for a positive electrode of a lithium battery, a material capable of removing and inserting lithium can be used as an active material, and it is suitable for a lithium secondary battery by filling such an aluminum porous body. An electrode can be obtained. Examples of the material for the positive electrode active material include lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium nickel cobaltate (LiCo _0.3 Ni _0.7 O ₂ ), and lithium manganate (LiMn ₂ O _4). ), Lithium titanate (Li ₄ Ti ₅ O ₁₂ ), lithium manganate compound (LiM _y Mn _2−y O ₄ ); M = Cr, Co, Ni), lithium acid, or the like is used. The active material is used in combination with a conductive additive and a binder. Examples thereof include transition metal oxides such as olivine compounds which are conventional lithium iron phosphate and its compounds (LiFePO ₄ , LiFe _0.5 Mn _0.5 PO ₄ ). Further, the transition metal element contained in these materials may be partially substituted with another transition metal element.

Still other positive electrode active materials include, for example, TiS ₂ , V ₂ S ₃ , FeS, FeS ₂ , LiMS _x (M is a transition metal element such as Mo, Ti, Cu, Ni, Fe, or Sb, Sn, Examples thereof include sulfide-based chalcogenides such as Pb), lithium metal having a metal oxide such as TiO ₂ , Cr ₃ O ₈ , V ₂ O ₅ , and MnO ₂ as a skeleton. Here, the above-described lithium titanate ((Li ₄ Ti ₅ O ₁₂ ) can also be used as a negative electrode active material.

-Electrolyte used in lithium batteries-
As the non-aqueous electrolyte, a polar aprotic organic solvent is used, and specifically, ethylene carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, γ-butyrolactone, sulfolane and the like are used. As the supporting salt, lithium tetrafluoroborate, lithium hexafluorophosphate, and an imide salt are used. Although it is preferable that the concentration of the supporting salt serving as an electrolyte is high, a concentration around 1 mol / L is generally used because there is a limit to dissolution.

-Solid electrolyte filled in porous aluminum-
In addition to the active material, a solid electrolyte may be added and filled. By filling an aluminum porous body with an active material and a solid electrolyte, it can be made suitable for an electrode of an all-solid-state lithium battery. However, the proportion of the active material in the material filled in the aluminum porous body is preferably 50% by mass or more, more preferably 70% by mass or more, from the viewpoint of securing the discharge capacity.

  As the solid electrolyte, a sulfide-based solid electrolyte having high lithium ion conductivity is preferably used. Examples of such a sulfide-based solid electrolyte include a sulfide-based solid electrolyte containing lithium, phosphorus, and sulfur. It is done. The sulfide solid electrolyte may further contain an element such as O, Al, B, Si, and Ge.

Such a sulfide-based solid electrolyte can be obtained by a known method. For example, lithium sulfide (Li ₂ S) and diphosphorus pentasulfide (P ₂ S ₅ ) are prepared as starting materials, and the ratio of Li ₂ S and P ₂ S ₅ is about 50:50 to 80:20 in molar ratio. And a method of melting and quenching the mixture (melting and quenching method) and a method of mechanically milling the mixture (nocical milling method).

  The sulfide-based solid electrolyte obtained by the above method is amorphous. Although it can be used in this amorphous state, it may be heat-treated to obtain a crystalline sulfide solid electrolyte. Crystallization can be expected to improve lithium ion conductivity.

-Filling the porous aluminum with active material-
For filling the active material (the active material and the solid electrolyte), for example, a known method such as an immersion filling method or a coating method can be used. Examples of the coating method include roll coating method, applicator coating method, electrostatic coating method, powder coating method, spray coating method, spray coater coating method, bar coater coating method, roll coater coating method, dip coater coating method, doctor Examples thereof include a blade coating method, a wire bar coating method, a knife coater coating method, a blade coating method, and a screen printing method.

  When filling the active material (active material and solid electrolyte), for example, a conductive additive and a binder are added as necessary, and an organic solvent and water are mixed therewith to prepare a positive electrode mixture slurry. This slurry is filled into an aluminum porous body using the above method. For example, carbon black such as acetylene black (AB) and ketjen black (KB) and carbon fiber such as carbon nanotube (CNT) can be used as the conductive auxiliary, and polyfluoride can be used as the binder, for example. Vinylidene (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), xanthan gum and the like can be used.

  The organic solvent used when preparing the positive electrode mixture slurry has an adverse effect on the material (that is, the active material, the conductive additive, the binder, and, if necessary, the solid electrolyte) filled in the aluminum porous body. If not, it can be selected as appropriate. Examples of such organic solvents include n-hexane, cyclohexane, heptane, toluene, xylene, trimethylbenzene, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, vinyl ethylene carbonate. , Tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, ethylene glycol, N-methyl-2-pyrrolidone and the like. Moreover, when using water for a solvent, you may use surfactant in order to improve a filling property.

(Capacitor)
FIG. 5 is a schematic cross-sectional view showing an example of a capacitor using a capacitor electrode material. In the organic electrolyte solution 143 partitioned by the separator 142, an electrode material in which an electrode active material is supported on a porous aluminum body is disposed as a polarizable electrode 141. The electrode material 141 is connected to the lead wire 144, and the whole is housed in the case 145. By using the aluminum porous body as a current collector, the surface area of the current collector is increased and the contact area with the activated carbon as the active material is increased, so that a capacitor capable of high output and high capacity can be obtained.

In order to manufacture an electrode for a capacitor, activated carbon is filled as an active material in an aluminum porous body current collector. Activated carbon is used in combination with a conductive aid and a binder.
In order to increase the capacity of the capacitor, it is better that the amount of the activated carbon as the main component is large, and the activated carbon is preferably 90% or more in terms of the composition ratio after drying (after removal of the solvent). Moreover, although a conductive auxiliary agent and a binder are necessary, it is a factor of a capacity | capacitance fall, and since a binder becomes a factor which increases internal resistance further, it is better to have as few as possible. The conductive assistant is preferably 10% by mass or less, and the binder is preferably 10% by mass or less.

Activated carbon has a specific surface area of preferably 1000 m ² / g or more because the larger the surface area, the larger the capacity of the capacitor. Activated carbon can use plant-derived coconut shells, petroleum-based materials, and the like. In order to improve the surface area of the activated carbon, it is preferable to perform activation treatment using water vapor or alkali.

  An activated carbon paste is obtained by mixing and stirring the electrode material mainly composed of the activated carbon. The activated carbon paste is filled in the current collector, dried, and compressed by a roller press or the like as necessary, thereby improving the density and obtaining a capacitor electrode.

-Filling of porous carbon with activated carbon-
The activated carbon can be filled using a known method such as a dip filling method or a coating method. Examples of the coating method include roll coating method, applicator coating method, electrostatic coating method, powder coating method, spray coating method, spray coater coating method, bar coater coating method, roll coater coating method, dip coater coating method, doctor Examples thereof include a blade coating method, a wire bar coating method, a knife coater coating method, a blade coating method, and a screen printing method.

  When the activated carbon is filled, for example, a conductive additive or a binder is added as necessary, and an organic solvent or water is mixed therewith to prepare a positive electrode mixture slurry. This slurry is filled into an aluminum porous body using the above method. For example, carbon black such as acetylene black (AB) and ketjen black (KB) and carbon fiber such as carbon nanotube (CNT) can be used as the conductive auxiliary, and polyfluoride can be used as the binder, for example. Vinylidene (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), xanthan gum and the like can be used.

  The organic solvent used when preparing the positive electrode mixture slurry has an adverse effect on the material (that is, the active material, the conductive additive, the binder, and, if necessary, the solid electrolyte) filled in the aluminum porous body. If not, it can be selected as appropriate. Examples of such organic solvents include n-hexane, cyclohexane, heptane, toluene, xylene, trimethylbenzene, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, vinyl ethylene carbonate. , Tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, ethylene glycol, N-methyl-2-pyrrolidone and the like. Moreover, when using water for a solvent, you may use surfactant in order to improve a filling property.

-Manufacture of capacitors-
Two of the electrodes obtained as described above are punched out to a suitable size, and are opposed to each other with a separator interposed therebetween. The separator is preferably a porous film or a non-woven fabric made of cellulose or polyolefin resin. And it accommodates in a cell case using a required spacer, and impregnates electrolyte solution. Finally, the electric double layer capacitor can be manufactured by sealing the case with an insulating gasket. When a non-aqueous material is used, it is preferable to sufficiently dry materials such as electrodes in order to reduce the moisture in the capacitor as much as possible. The capacitor may be manufactured in an environment with little moisture, and the sealing may be performed in a reduced pressure environment. The capacitor is not particularly limited as long as the current collector and electrode of the present invention are used, and the capacitor may be manufactured by other methods.

  The electrolyte can be used for both aqueous and non-aqueous electrolytes, but the non-aqueous electrolyte is preferred because the voltage can be set higher. In an aqueous system, potassium hydroxide or the like can be used as an electrolyte. As non-aqueous systems, there are many ionic liquids in combination of cations and anions. As the cation, lower aliphatic quaternary ammonium, lower aliphatic quaternary phosphonium, imidazolinium and the like are used, and as the anion, imide compounds such as metal chloride ion, metal fluoride ion, and bis (fluorosulfonyl) imide Etc. are known. Further, there are polar aprotic organic solvents, and specifically, ethylene carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, γ-butyrolactone, sulfolane and the like are used. As the supporting salt in the non-aqueous electrolyte, lithium tetrafluoroborate, lithium hexafluorophosphate, or the like is used.

(Lithium ion capacitor)
FIG. 6 is a schematic cross-sectional view showing an example of a lithium ion capacitor using a lithium ion capacitor electrode material. In the organic electrolyte solution 143 partitioned by the separator 142, an electrode material carrying a positive electrode active material on a porous aluminum body is arranged as a positive electrode 146, and an electrode material carrying a negative electrode active material on a current collector is arranged as a negative electrode 147. ing. The positive electrode 146 and the negative electrode 147 are connected to lead wires 148 and 149, respectively, and are entirely housed in the case 145. By using the aluminum porous body as a current collector, the surface area of the current collector is increased, and a lithium ion capacitor capable of increasing the output and capacity can be obtained even when activated carbon as an active material is thinly applied.

-Positive electrode-
In order to manufacture an electrode for a lithium ion capacitor, activated carbon is filled as an active material in an aluminum porous body current collector. Activated carbon is used in combination with a conductive aid and a binder.
In order to increase the capacity of the lithium ion capacitor, it is better that the amount of activated carbon as a main component is large, and the activated carbon is preferably 90% or more in terms of the composition ratio after drying (after solvent removal). Moreover, although a conductive auxiliary agent and a binder are necessary, it is a factor of a capacity | capacitance fall, and since a binder becomes a factor which increases internal resistance further, it is better to have as few as possible. The conductive assistant is preferably 10% by mass or less, and the binder is preferably 10% by mass or less.

Activated carbon has a specific surface area of 1000 m ² / g or more because the larger the surface area, the larger the capacity of the lithium ion capacitor. Activated carbon can use plant-derived coconut shells, petroleum-based materials, and the like. In order to improve the surface area of the activated carbon, it is preferable to perform activation treatment using water vapor or alkali. In addition, ketjen black, acetylene black, carbon fiber, or a composite material thereof can be used as the conductive auxiliary. As the binder, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethylcellulose, xanthan gum and the like can be used. As the solvent, water or an organic solvent may be appropriately selected depending on the kind of the binder. In organic solvents, N-methyl-2-pyrrolidone is often used. Moreover, when using water for a solvent, you may use surfactant in order to improve a filling property.

  An activated carbon paste is obtained by mixing and stirring the electrode material mainly composed of the activated carbon. The activated carbon paste is filled in the current collector, dried, and compressed by a roller press or the like as necessary to improve the density, thereby obtaining an electrode for a lithium ion capacitor.

-Filling of porous carbon with activated carbon-
The activated carbon can be filled using a known method such as a dip filling method or a coating method. Examples of the coating method include roll coating method, applicator coating method, electrostatic coating method, powder coating method, spray coating method, spray coater coating method, bar coater coating method, roll coater coating method, dip coater coating method, doctor Examples thereof include a blade coating method, a wire bar coating method, a knife coater coating method, a blade coating method, and a screen printing method.

  When the activated carbon is filled, for example, a conductive additive or a binder is added as necessary, and an organic solvent or water is mixed therewith to prepare a positive electrode mixture slurry. This slurry is filled into an aluminum porous body using the above method. For example, carbon black such as acetylene black (AB) and ketjen black (KB) and carbon fiber such as carbon nanotube (CNT) can be used as the conductive auxiliary, and polyfluoride can be used as the binder, for example. Vinylidene (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), xanthan gum and the like can be used.

  The organic solvent used when preparing the positive electrode mixture slurry has an adverse effect on the material (that is, the active material, the conductive additive, the binder, and, if necessary, the solid electrolyte) filled in the aluminum porous body. If not, it can be selected as appropriate. Examples of such organic solvents include n-hexane, cyclohexane, heptane, toluene, xylene, trimethylbenzene, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, vinyl ethylene carbonate. , Tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, ethylene glycol, N-methyl-2-pyrrolidone and the like. Moreover, when using water for a solvent, you may use surfactant in order to improve a filling property.

-Negative electrode-
The negative electrode is not particularly limited, and a conventional negative electrode for a lithium battery can be used. However, since the conventional electrode using a copper foil as a current collector has a small capacity, it is made of copper or nickel such as the aforementioned foamed nickel. An electrode in which a porous material is filled with an active material is preferable. In order to operate as a lithium ion capacitor, it is preferable that the negative electrode is doped with lithium ions in advance. A known method can be used as the doping method. For example, a method of attaching a lithium metal foil on the negative electrode surface and immersing it in an electrolyte solution, or placing an electrode with lithium metal in a lithium ion capacitor and assembling the cell, between the negative electrode and the lithium metal electrode And a method of electrically doping with an electric current, or a method of assembling an electrochemical cell with a negative electrode and lithium metal, and taking out and using the negative electrode electrically doped with lithium.
In any method, it is better to increase the amount of lithium doping in order to sufficiently lower the potential of the negative electrode. However, if the remaining capacity of the negative electrode is smaller than the positive electrode capacity, the capacity of the lithium ion capacitor is reduced, so the positive electrode capacity is not doped. It is preferable to leave it in

-Electrolyte used in lithium ion capacitors-
The same electrolyte as the nonaqueous electrolyte used for the lithium battery is used. As the non-aqueous electrolyte, a polar aprotic organic solvent is used, and specifically, ethylene carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, γ-butyrolactone, sulfolane and the like are used. As the supporting salt, lithium tetrafluoroborate, lithium hexafluorophosphate, and an imide salt are used.

-Fabrication of lithium ion capacitors-
The electrode obtained as described above is punched out to an appropriate size and is made to face the negative electrode with a separator interposed therebetween. The negative electrode may be doped with lithium ions by the above-described method, and when a method of doping after assembling the cell is taken, an electrode connected with lithium metal may be arranged in the cell. The separator is preferably a porous film or a non-woven fabric made of cellulose or polyolefin resin. And it accommodates in a cell case using a required spacer, and impregnates electrolyte solution. Finally, the case is covered and sealed with an insulating gasket, so that a lithium ion capacitor can be produced.
In order to reduce the moisture in the lithium ion capacitor as much as possible, it is preferable that the material such as the electrode is sufficiently dried. In addition, the lithium ion capacitor may be manufactured in an environment with little moisture, and the sealing may be performed in a reduced pressure environment. Note that the lithium ion capacitor is not particularly limited as long as the current collector and the electrode of the present invention are used, and may be manufactured by a method other than this.

(Electrode for molten salt battery)
The aluminum porous body can also be used as an electrode material for a molten salt battery. When an aluminum porous body is used as a positive electrode material, a metal compound capable of intercalating cations of a molten salt serving as an electrolyte, such as sodium chromite (NaCrO ₂ ) and titanium disulfide (TiS ₂ ) as an active material Is used. The active material is used in combination with a conductive additive and a binder. As the conductive assistant, acetylene black or the like can be used. As the binder, polytetrafluoroethylene (PTFE) or the like can be used. When sodium chromite is used as the active material and acetylene black is used as the conductive additive, PTFE is preferable because both can be firmly fixed.

  The aluminum porous body can also be used as a negative electrode material for a molten salt battery. When an aluminum porous body is used as a negative electrode material, sodium alone, an alloy of sodium and another metal, carbon, or the like can be used as an active material. The melting point of sodium is about 98 ° C., and the metal softens as the temperature rises. Therefore, it is preferable to alloy sodium with other metals (Si, Sn, In, etc.). Of these, an alloy of sodium and Sn is particularly preferable because it is easy to handle. Sodium or a sodium alloy can be supported on the surface of the porous aluminum body by a method such as electrolytic plating or hot dipping. Alternatively, a metal alloy (such as Si) to be alloyed with sodium is attached to the aluminum porous body by a method such as plating, and then charged in a molten salt battery to form a sodium alloy.

  FIG. 7 is a schematic cross-sectional view showing an example of a molten salt battery using the battery electrode material. The molten salt battery includes a positive electrode 121 carrying a positive electrode active material on the surface of an aluminum skeleton part of an aluminum porous body, a negative electrode 122 carrying a negative electrode active material on the surface of the aluminum skeleton part of an aluminum porous body, and an electrolyte. A separator 123 impregnated with molten salt is housed in a case 127. Between the upper surface of the case 127 and the negative electrode, a pressing member 126 including a pressing plate 124 and a spring 125 that presses the pressing plate is disposed. By providing the pressing member, even when there is a volume change of the positive electrode 121, the negative electrode 122, and the separator 123, the respective members can be brought into contact with each other by being pressed uniformly. The current collector (aluminum porous body) of the positive electrode 121 and the current collector (aluminum porous body) of the negative electrode 122 are connected to the positive electrode terminal 128 and the negative electrode terminal 129 by lead wires 130, respectively.

  As the molten salt as the electrolyte, various inorganic salts or organic salts that melt at the operating temperature can be used. As the cation of the molten salt, alkali metals such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb) and cesium (Cs), beryllium (Be), magnesium (Mg), calcium (Ca) One or more selected from alkaline earth metals such as strontium (Sr) and barium (Ba) can be used.

In order to lower the melting point of the molten salt, it is preferable to use a mixture of two or more salts. For example, when potassium bis (fluorosulfonyl) amide <K—N (SO ₂ F) ₂ ; KFSA> and sodium bis (fluorosulfonyl) amide <Na—N (SO ₂ F) ₂ ; NaFSA> are used in combination, the battery The operating temperature can be 90 ° C. or lower.

  The molten salt is used by impregnating the separator. A separator is for preventing a positive electrode and a negative electrode from contacting, and a glass nonwoven fabric, a porous porous resin body, etc. can be used for it. The above positive electrode, negative electrode, and separator impregnated with molten salt are stacked and housed in a case to be used as a battery.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, these Examples are illustrations, Comprising: The aluminum porous body of this invention is not limited to these. The scope of the present invention is defined by the scope of the claims, and includes meanings equivalent to the scope of the claims and all modifications within the scope.

[Example 1]
-Resin molding-
As a resin molded body serving as a base material of a porous aluminum body, a urethane foam having a gas efficiency of 96%, a number of cells of 46 / inch, a pore diameter of about 550 μm, and a thickness of 1.0 mm is prepared. Disconnected.

-Formation of conductive layer-
The urethane foam was immersed in a carbon suspension and dried to form a conductive layer having carbon particles attached to the entire surface of the urethane foam. The components of the carbon suspension include 25% graphite and carbon black, and include a resin binder, a penetrating agent, and an antifoaming agent. The particle size of carbon black was 0.5 μm.

-Molten salt electroplating-
The urethane foam having a conductive layer formed on the surface is used as a work, set in a jig having a power feeding function, and then placed in a glove box having an argon atmosphere and low moisture (dew point -30 ° C. or lower). It was immersed in a molten salt aluminum plating bath (33 mol% EMIC-67 mol% AlCl ₃ ). The jig on which the workpiece was set was connected to the cathode side of the rectifier, and a counter electrode aluminum plate (purity 99.99 mass%) was connected to the anode side.
A structure in which an aluminum film having a mass of 140 g / m ² was formed on the surface of the urethane foam was obtained by plating by applying a direct current having a current density of 6.5 A / dm ² for 20 minutes. Stirring was performed with a stirrer using a Teflon (registered trademark) rotor. The current density is a value calculated with an apparent area of urethane foam.

-Removal of resin-
The resin structure obtained above was taken out of the plating bath, and washed with water having a liquid temperature of 10 ° C. in a state where the amount of plating solution deposited was 18 mL / m ² . After the water washing treatment, the structure was thoroughly dried and heat-treated at 610 ° C. for 20 minutes in an atmosphere with a dew point temperature of −20 ° C. As a result, the urethane resin was burned out, and an aluminum porous body was obtained.

-Treatment with acid-
Said aluminum porous body was immersed in 12 mass% hydrochloric acid for 5 minutes. Thereafter, the porous aluminum body was taken out, washed with water, thoroughly drained, and then heated to 500 ° C. and sufficiently dried to obtain an aluminum porous body A of the present invention.

[Example 2]
In the resin removal step of Example 1, instead of washing the resin structure after molten salt electroplating with water, a washing treatment was performed using ethanol. After washing with ethanol, the resin structure was washed with water and dried well, and then the resin was burned and removed. Except these, the aluminum porous body B was obtained by performing the same operation as Example 1.

[Example 3]
In the resin removal step of Example 1, the resin structure after molten salt electroplating was sprayed with air having a dew point temperature of −50 ° C., and then washed with water. Then, after the water washing treatment, the resin structure was thoroughly dried, and heat treatment was performed at 610 ° C. for 20 minutes in an atmosphere having a dew point temperature of −20 ° C. Except these, the aluminum porous body C was obtained by performing the same operation as Example 1.

[Comparative Example 1]
In Example 1, the aluminum porous body D was obtained by performing operation similar to Example 1 except not having processed with the acid.

(Evaluation)
-Observation of skeletal cross-section-
When the aluminum porous body A obtained as described above was observed with an electron microscope, as shown in FIG. 1, the surface of the hollow portion of the skeleton had a smooth surface with the porous layer almost removed. Was confirmed. The thickness of the porous layer in the hollow portion of the skeleton was 0.8 μm or less.
Similarly, when the aluminum porous body D was observed with an electron microscope, as shown in FIG. 2, a thick porous layer was formed on the surface of the hollow portion of the skeleton. The thickness of the porous layer in the hollow portion of the skeleton was 1.3 μm.

−Moisture adsorption amount−
The moisture adsorption amount of the aluminum porous bodies A to D was measured by the Karl Fischer coulometric titration method.
First, aluminum porous bodies A to D were cut into 10 mm × 50 mm squares for measurement, and five test pieces A to D were prepared. And these test pieces AD were heat-processed for 10 minutes in a 300 degreeC nitrogen gas atmosphere, and were fully dried. Thereafter, the test piece was exposed to an atmosphere having a dew point of −20 ° C. for 24 hours.
The moisture adsorption amount of the test piece pretreated as described above was measured by Karl Fischer coulometric titration using a moisture vaporizer heated to 300 ° C. The end condition of the titration was the time when the detected water content became “background value + 0.1 μg / sec”.

As a result of measuring the moisture adsorption amount of each aluminum porous body as described above, the moisture adsorption amount (mg / m ² ) of the aluminum porous bodies A to C is much smaller than the moisture adsorption amount of the aluminum porous body D. It was confirmed that In addition, the aluminum porous bodies A to C had a small amount of re-adsorbing moisture in the atmosphere. These results are shown in FIG.

-Manufacture of capacitors-
Using aluminum porous bodies A to D as current collectors A to D, pores of current collectors A to D were filled with an active material to prepare electrodes A to D. During electrode preparation, a drying process was performed at 150 ° C. and 5 Torr for 2 hours.
When the electric double layer capacitors A to D were prepared and evaluated using the electrodes A to D, no generation of gas was confirmed for the electric double layer capacitors A to C. From which gas generation was confirmed.

60 Lithium battery 61 Positive electrode 62 Negative electrode 63 Solid electrolyte layer (SE layer)
64 Positive electrode layer (positive electrode body)
65 positive electrode current collector 66 negative electrode layer 67 negative electrode current collector 121 positive electrode 122 negative electrode 123 separator 124 pressing plate 125 spring 126 pressing member 127 case 128 positive electrode terminal 129 negative electrode terminal 130 lead wire 141 polarizable electrode 142 separator 143 organic electrolyte 144 lead Wire 145 Case 146 Positive electrode 147 Negative electrode 148 Lead wire 149 Lead wire

Claims (10)

A porous aluminum body having a hollow three-dimensional network structure,
The aluminum porous body has a porous layer having a thickness of 1.0 μm or less in the hollow portion of the skeleton, and the water adsorption amount of the aluminum porous body is 30 mg / m ² or less. Forming an aluminum film by molten salt electroplating on the surface of a resin base material having a three-dimensional network structure;
Removing the substrate;
A step of treating an aluminum porous body having a hollow three-dimensional network structure formed by removing the substrate with an acid or a base;
The manufacturing method of the aluminum porous body which has this.   The manufacturing method of the aluminum porous body of Claim 2 with which the said base material is electrically conductive-processed by carbon application | coating. ^{3. The} method according to claim 2, further comprising a step of removing the liquid so that the amount of the plating solution adhering to the aluminum film is 0.1 mL / m ² or more and 30 mL / m ² or less before the step of removing the substrate. The manufacturing method of the aluminum porous body of Claim 3.   The manufacturing method of the aluminum porous body as described in any one of Claims 2-4 which has the process of removing the plating solution adhering to the said aluminum film with an organic solvent before the process of removing the said base material.   6. The method according to claim 2, further comprising supplying air having a dew point temperature of −50 ° C. or higher and −30 ° C. or lower to the aluminum film before the step of removing the base material. A method for producing a porous aluminum body.   The porous aluminum according to any one of claims 2 to 6, wherein in the step of removing the substrate, heat treatment is performed at a temperature of 370 ° C or higher and lower than a melting point of aluminum in an atmosphere having a dew point temperature of 0 ° C or lower. Body manufacturing method.   The electrical power collector for electrochemical devices which consists of an aluminum porous body of Claim 1.   The electrode for electrochemical devices which has an active material in the pore part of the aluminum porous body of Claim 1.   An electrochemical device using the electrode according to claim 9.