JP2012251211A - Method for producing aluminum structure, and aluminum structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aluminum structure using a porous resin molded body having a three-dimensional network structure, the method formable of an aluminum structure that is reduced in the amount of impurities and obtainable of an aluminum porous body having an especially large area.SOLUTION: The method for producing the aluminum structure includes: an electrical conductivity-imparting step wherein a conductive coating material containing a conductive carbon is applied over the surface of a resin molded body, thereby imparting the resin molded body with electrical conductivity; a plating step wherein the surface of the resin molded body, which has been imparted with electrical conductivity, is plated with aluminum in a molten salt, thereby forming an aluminum layer; and a heat treatment step wherein the resin molded body is removed by a heat treatment. The method for producing the aluminum structure is characterized in that the conductive carbon is carbon black that has an average particle diameter of 0.003-0.05 μm.

Description

  The present invention relates to an aluminum structure that can be suitably used as a metal porous body in applications such as various filters and battery electrodes, and a method for producing the same.

  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, cermet made of nickel (manufactured by Sumitomo Electric Industries, Ltd .: registered trademark) is used as an electrode material for batteries such as nickel metal hydride batteries and nickel cadmium batteries. 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. This can be obtained by forming a nickel layer on the surface of the porous resin skeleton having continuous air holes such as urethane foam, then heat-treating it to decompose the foamed resin molding, and further reducing the nickel. 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.

  Aluminum is excellent in electrical conductivity and corrosion resistance, and is a lightweight material. In battery applications, for example, as a positive electrode of a lithium ion battery, an aluminum foil whose surface is coated with an active material such as lithium cobaltate is used. In order to improve the capacity of the positive electrode, it is conceivable that aluminum is made porous to increase the surface area and the aluminum is filled with an active material. This is because the active material can be used even if the electrode is thickened, and the active material utilization rate per unit area is improved.

  As a method for producing a porous aluminum body, Patent Document 1 discloses that a metal aluminum layer having a thickness of 2 to 20 μm is formed by subjecting a three-dimensional network plastic substrate having an internal communication space to aluminum vapor deposition by an arc ion plating method. A method is described. In Patent Document 2, a film made of a metal (such as copper) that forms a eutectic alloy below the melting point of aluminum is formed on the skeleton of a foamed resin molding having a three-dimensional network structure, and then an aluminum paste is applied. In addition, a method is described in which a metal porous body is obtained by performing heat treatment at a temperature of 550 ° C. or higher and 750 ° C. or lower in a non-oxidizing atmosphere to eliminate organic components (foamed resin) and sinter aluminum powder.

  On the other hand, aluminum plating has a high affinity for oxygen of aluminum, and the potential is lower than that of hydrogen, so that it is difficult to perform electroplating in an aqueous plating bath. For this reason, conventionally, electroplating of aluminum has been studied using a non-aqueous plating bath. For example, as a technique for plating aluminum for the purpose of preventing oxidation of the surface of a metal, Patent Document 3 uses a low melting point composition in which onium halide and aluminum halide are mixed and melted as a plating bath. An electrolytic aluminum plating method is disclosed, in which aluminum is deposited on the cathode while maintaining the amount at 2 wt% or less.

Japanese Patent No. 3413662 JP-A-8-170126 Japanese Patent No. 3202072

  According to the method of Patent Document 1, it is said that an aluminum porous body having a thickness of 2 to 20 μm can be obtained. However, since it is based on a gas phase method, it is difficult to produce a large area, and the thickness and porosity of the substrate are difficult. In some cases, it is difficult to form a uniform layer up to the inside. 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. Furthermore, when a thick film is formed, there is a possibility that the film may crack or aluminum may fall off. According to the method of Patent Document 2, a layer that forms a eutectic alloy with aluminum is formed, and a high-purity aluminum layer cannot be formed. On the other hand, although the electroplating method of aluminum itself is known, it is only possible to perform plating on the metal surface, and electroplating on the resin surface, especially on the surface of the porous resin molded body having a three-dimensional network structure. The method of plating was not known. This is considered to be affected by problems such as dissolution of the porous resin in the plating bath.

  The present inventors can form aluminum porous body with high purity by forming a thick film uniformly, even if it is a porous resin molded body having a three-dimensional network structure. As a method that can be performed, after conceiving the surface of a resin molded body having a three-dimensional network structure such as polyurethane or melamine, the inventors have conceived a method for producing an aluminum porous body in which aluminum is plated in a molten salt bath. The application has been filed. Methods for making the surface of the resin molded body conductive include electroless plating of conductive metals such as nickel, adhesion of metals such as aluminum by vapor phase methods (sputtering, vapor deposition, etc.), and conductive particles such as carbon Examples include application of conductive paint. After plating with aluminum, the resin molded body is removed to obtain an aluminum structure mainly composed of aluminum.

  When the resin molded body is made conductive using a metal other than aluminum such as nickel, a metal other than aluminum remains in the finished aluminum structure and becomes an impurity. In applications that require the purity of aluminum, such as battery electrodes, such conductive methods are not suitable because impurities cannot provide good characteristics. A high-purity aluminum structure can be obtained by conducting with aluminum, but in order to conduct with aluminum, it is necessary to use a vapor phase method such as vapor deposition or sputtering, resulting in an increase in manufacturing cost.

  Application of a conductive paint containing conductive carbon is a relatively simple method and can be manufactured at low cost. Further, no metal other than aluminum such as nickel remains. However, when conducting with conductive carbon, it is difficult to completely remove the conductive carbon in the resin molding removal process after the aluminum plating process, and carbon remains as an impurity in the finished aluminum structure. To do. If the amount of carbon remaining in the aluminum structure increases, the aluminum structure tends to break starting from the residual carbon, which causes a reduction in strength of the aluminum structure. Residual carbon can also cause poor welding in the battery electrode manufacturing process.

  Therefore, the present invention is a method for producing an aluminum structure using a resin molded body, particularly a porous resin molded body having a three-dimensional network structure, and a method capable of producing an aluminum structure with less impurities, and It is an object of the present invention to provide a method capable of obtaining an aluminum structure that can be manufactured in a large area and is particularly suitable for electrode applications.

  The present invention provides a conductive step of applying a conductive paint containing conductive carbon to the surface of a resin molded body to make the resin molded body conductive, and the surface of the resin molded body that has been made conductive is in a molten salt. A method for producing an aluminum structure, comprising: a plating step of plating aluminum to form an aluminum layer; and a heat treatment step of removing the resin molded body by heat treatment, wherein the conductive carbon has an average particle size of 0.1. A method for producing an aluminum structure, characterized in that the carbon black is 003 μm or more and 0.05 μm or less.

  Conventionally, graphite having an average particle diameter of about 1.5 μm has been used as conductive carbon for conducting a resin molded body in the production of nickel cermet and the like. In the production of nickel cermet, the resin molded product is removed in a high temperature atmosphere of about 600 ° C. to 800 ° C. in the atmosphere, and further reduced at 1000 ° C. In such a high temperature atmosphere, even when graphite having a relatively large average particle diameter is used, the conductive carbon can be decomposed and removed well. However, the melting point of aluminum is 660 ° C., and it is necessary to remove the resin molded body below this temperature. In addition, aluminum is easy to oxidize, and once oxidized, it cannot be reduced at a temperature below the melting point. Therefore, the heat treatment temperature is preferably low. As a result of studying the types of conductive carbon that can be removed well even by such low-temperature treatment, the average particle size is 0.003 μm or more and 0.05 μm, and amorphous conductive carbon black having no crystallinity is obtained. It has been found that by using it, carbon can be removed satisfactorily even at a relatively low temperature, and an aluminum structure having a small amount of carbon residue can be obtained.

  The heat treatment step is preferably performed in an atmosphere containing oxygen at a temperature of 500 ° C. to 640 ° C. (Claim 2). When the temperature exceeds 640 ° C., the oxidation of aluminum is likely to proceed, and the current collecting characteristics are deteriorated when used as an electrode material for a battery. On the other hand, if the temperature is lower than 500 ° C., the residual amount of conductive carbon increases. A more preferable heat treatment temperature is 580 ° C. or more and 620 ° C. or less. Further, when the heat treatment step is performed in an atmosphere containing oxygen, the conductive carbon can be removed in a short time.

  In particular, when a resin molded body having a complicated skeleton structure such as a porous resin body having a three-dimensional network structure is used, an aluminum structure having a high porosity can be obtained, which can be suitably used for electrode applications (claims). Item 3). A resin porous body having a high porosity can be obtained, and urethane that can be satisfactorily decomposed in the heat treatment step is preferred as a resin molded body.

  An aluminum structure is obtained by the above steps. The aluminum structure has a high purity, and the carbon content can be 2% or less (claim 6). The carbon content in the aluminum structure can be measured by a high frequency combustion infrared absorption method using a high frequency induction heating furnace.

  ADVANTAGE OF THE INVENTION According to this invention, the method which can form the aluminum structure with few amounts of impurities using the resin molding, especially the porous resin molding which has a three-dimensional network structure, and an aluminum structure are provided. be able to.

It is a flowchart which shows the manufacturing process of the aluminum structure by this invention. It is a cross-sectional schematic diagram explaining the manufacturing process of the aluminum structure by this invention. It is a surface enlarged photograph which shows the structure of the urethane foam resin as an example of a porous resin molding. It is a figure explaining an example of the continuous electroconductivity process of the resin molding body surface with an electroconductive coating material. It is a figure explaining an example of the aluminum continuous plating process by molten salt plating. It is a cross-sectional schematic diagram which shows the structural example which applied the aluminum porous body to the molten salt battery. It is a cross-sectional schematic diagram which shows the structural example which applied the aluminum porous body to the electrical double layer capacitor.

  Embodiments of the present invention will be described below. In the drawings to be referred to below, the same reference numerals are the same or corresponding parts. The present invention is not limited to this, but is defined by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

(Aluminum structure manufacturing process)
FIG. 1 is a flow diagram showing a manufacturing process of an aluminum structure according to the present invention. FIG. 2 schematically shows a state in which an aluminum structure is formed using a resin molded body as a core material corresponding to the flowchart. The flow of the entire manufacturing process will be described with reference to both drawings. First, preparation 101 of the base resin molded body is performed. FIG. 2A is an enlarged schematic view showing a part of a cross section of a resin in which the surface of a foamed resin molded body having continuous air holes is enlarged as an example of the base resin molded body. The pores are formed with the foamed resin molded body 1 as a skeleton. Next, the surface 102 of the resin molded body is made conductive. By this step, a thin conductive layer 2 is formed on the surface of the resin molded body 1 as shown in FIG. Subsequently, aluminum plating 103 in molten salt is performed to form an aluminum plating layer 3 on the surface of the resin molded body on which the conductive layer is formed (FIG. 2C). As a result, an aluminum-coated resin molded body having an aluminum plating layer 3 formed on the surface using the resin molded body as a base material is obtained. Thereafter, removal 104 of the base resin molded body is performed. By heat-treating the aluminum-coated resin molded body to decompose and remove the foamed resin molded body 1, an aluminum structure (porous body) in which only the metal layer remains can be obtained (FIG. 2 (d)). Hereinafter, each step will be described in order.

(Preparation of porous resin molding)
A foamed resin molded body made of urethane having a three-dimensional network structure and continuous air holes is prepared. A resin molded body having an arbitrary shape can be selected as long as it has continuous pores (continuous vent 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 article. The foamed resin molded article preferably has a porosity of 80% to 98% and a pore diameter of 50 μm to 500 μm. Foamed urethane has a high porosity, and has a pore communication property and is excellent in the uniformity of the pores, so that it can be preferably used as a foamed resin molding.

Foamed resin moldings often have residues such as foaming agents and unreacted monomers in the foam production process, and it is preferable to perform a washing treatment for the subsequent steps. As an example of the foamed resin molded article, a foamed urethane washed is shown in FIG. The resin molded body forms a three-dimensional network as a skeleton, thereby forming continuous pores as a whole. The urethane skeleton has a substantially triangular shape in a cross section perpendicular to the extending direction. Here, the porosity is defined by the following equation.
Porosity = (1− (weight of porous material [g] / (volume of porous material [cm ³ ] × material density))) × 100 [%]
Further, the pore diameter is obtained by enlarging the surface of the resin molded body with a micrograph or the like, counting the number of cells per inch (25.4 mm), and obtaining an average value as average pore diameter = 25.4 mm / cell number. .

(Conductivity of resin molding surface: Application of conductive paint)
A conductive paint using carbon black having an average particle size of 0.003 μm to 0.05 μm as conductive carbon is prepared. The conductive paint is a suspension containing conductive carbon, 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, the suspension is preferably maintained at 20 ° C to 40 ° C. The reason for this is that when the temperature of the suspension is less than 20 ° C., the uniform suspension state is lost, and only the binder forms a layer on the surface of the skeleton forming the belt-like structure of the synthetic resin molding. is there. 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.

  Carbon black, which is amorphous carbon, is used as the conductive carbon. The average particle size of the conductive carbon is 0.003 μm or more and 0.05 μm or less, more preferably 0.005 μm or more and 0.02 μm or less. If the average particle size is too large, the decomposability in the heat treatment process is lowered. On the other hand, if the average particle size is too small, it is difficult to ensure sufficient conductivity. In addition, let an average particle diameter be the value computed from the specific surface area measured using the specific surface area measuring apparatus.

  The carbon particles can be applied to the porous resin molded body by immersing the target resin molded body in the suspension and performing squeezing and drying. FIG. 4 is a diagram schematically showing a configuration of a processing apparatus for conducting a band-shaped porous resin molded body serving as a skeleton as an example of a practical manufacturing process. As shown in the figure, this apparatus includes a supply bobbin 12 for supplying a belt-shaped resin 11, a tank 15 containing a conductive paint suspension 14, a pair of squeezing rolls 17 disposed above the tank 15, A plurality of hot air nozzles 16 provided to face the side of the belt-like resin 11 to be wound, and a winding bobbin 18 that winds up the belt-like resin 11 after processing. Further, a deflector roll 13 for guiding the belt-shaped resin 11 is appropriately disposed. In the apparatus configured as described above, the strip-shaped resin 1 having a three-dimensional network structure is unwound from the supply bobbin 12, guided by the deflector roll 13, and immersed in the suspension in the tank 15. The strip-shaped resin 11 immersed in the suspension 14 in the tank 15 changes its direction upward and travels between the squeeze rolls 17 above the liquid level of the suspension 14. At this time, the distance between the squeezing rolls 17 is smaller than the thickness of the strip-shaped resin 11, and the strip-shaped resin 11 is compressed. Therefore, the excess suspension impregnated in the belt-shaped resin 11 is squeezed out and returned to the tank 15.

  Subsequently, the strip-shaped resin 11 changes the traveling direction again. Here, the suspension dispersion medium and the like are removed by hot air jetted by the hot air nozzle 16 composed of a plurality of nozzles, and the belt-like resin 11 is wound around the winding bobbin 18 after sufficiently drying. The temperature of the hot air ejected from the hot air nozzle 16 is preferably in the range of 40 ° C to 80 ° C. When the apparatus as described above is used, the conductive treatment can be carried out automatically and continuously, and a skeleton having a network structure without clogging and having a uniform conductive layer is formed. The metal plating in the next process can be performed smoothly.

(Formation of aluminum layer: Molten salt plating)
Next, electrolytic plating is performed in a molten salt to form an aluminum plating layer 3 on the surface of the resin molded body. A direct current is applied in a molten salt using a resin molded body having a conductive surface as a cathode and an aluminum plate having a purity of 99.99% as an anode. The thickness of the aluminum plating layer is 1 μm to 100 μm, preferably 5 μm to 20 μm. 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. Use of an organic molten salt bath that melts at a relatively low temperature is preferable because 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. Of these, 1-ethyl-3-methylimidazolium chloride (EMIC) and butylpyridinium chloride (BPC) are preferable. As the imidazolium salt, a salt containing an imidazolium cation having an alkyl group at the 1,3-position is preferably used. In particular, aluminum chloride, 1-ethyl-3-methylimidazolium chloride (AlCl ₃ -EMIC) based molten salt, It is most preferably used because it is highly stable and hardly decomposes.

  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. When an EMIC bath is used as the organic molten salt bath, the temperature of the plating bath is 10 ° C. to 60 ° C., preferably 25 ° C. to 45 ° C.

  When an imidazolium salt bath is used as the molten salt bath, it is preferable to add an organic solvent to the molten salt bath. Xylene is particularly preferably used as the organic solvent. Addition of an organic solvent, particularly xylene, can provide effects peculiar to the formation of an aluminum porous body. That is, the first feature that the aluminum skeleton forming the porous body is not easily broken and the second feature that uniform plating with a small difference in plating thickness between the surface portion and the inside of the porous body can be obtained. . The first feature is that by adding an organic solvent, the plating on the surface of the skeleton is improved from a granular shape (large irregularities look like particles in surface observation) to a flat shape, so that the thin skeleton is thin and strong. It will be. The second feature is that by adding an organic solvent to the molten salt bath, the viscosity of the molten salt bath is lowered, and the plating bath can easily flow into the fine network structure. In other words, when the viscosity is high, a new plating bath is easily supplied to the surface of the porous body, and conversely, it is difficult to supply the inside of the porous body. Thickness plating can be performed. The amount of the organic solvent added to the plating bath is preferably 25 to 57 mol%. If it is 25 mol% or less, it is difficult to obtain the effect of reducing the difference in thickness between the surface layer and the inside. If it is 57 mol% or more, the plating bath becomes unstable, and the plating solution and xylene are partially separated.

Furthermore, it is preferable that the method further includes a cleaning step using the organic solvent as a cleaning liquid after the step of plating with the molten salt bath to which the organic solvent is added. The plated resin surface needs to be washed to wash away the plating bath. Such cleaning after plating is usually performed with water. However, it is essential to avoid moisture in the imidazolium salt bath. However, if washing is performed with water, water is brought into the plating solution in the form of water vapor. Therefore, we want to avoid washing with water in order to prevent adverse effects on plating. Therefore, cleaning with an organic solvent is effective. Further, when an organic solvent is added to the plating bath as described above, a further advantageous effect can be obtained by washing with the organic solvent added to the plating bath. That is, the washed plating solution can be collected and reused relatively easily, and the cost can be reduced. For example, consider a case in which a plated body to which a bath in which xylene is added to molten salt AlCl ₃ -EMIC is adhered is washed with xylene. The washed liquid becomes a liquid containing more xylene than the plating bath used. Here, the molten salt AlCl ₃ -EMIC is not mixed with a certain amount or more in xylene, and is separated from the molten salt AlCl ₃ -EMIC containing xylene on the upper side and about 57 mol% of xylene on the lower side. The molten liquid can be recovered by pumping the liquid. Furthermore, since the boiling point of xylene is as low as 144 ° C., it is possible to adjust the xylene concentration in the recovered molten salt to the concentration in the plating solution by heating and reuse it. In addition, after washing | cleaning with an organic solvent, further washing | cleaning with water in the place different from a plating bath is also used preferably.

  FIG. 5 is a diagram schematically showing a configuration of an apparatus for continuously performing metal plating treatment on the belt-shaped resin. A configuration in which the belt-like resin 22 whose surface is made conductive is sent from the left to the right in the figure. The first plating tank 21 a includes a cylindrical electrode 24, a positive electrode 25 provided on the inner wall of the container, and a plating bath 23. By passing the strip-shaped resin 22 along the cylindrical electrode 24 through the plating bath 23, current can easily flow uniformly throughout the resin, and uniform plating can be obtained. The plating tank 21b is a tank for applying a thick and uniform plating, and is configured to be repeatedly plated in a plurality of tanks. Plating is performed by passing the belt-like resin 22 having a thin metal tank on the surface through a plating bath 28 while sequentially feeding it by an electrode roller 26 that also serves as a feed roller and an external power feeding negative electrode. In the plurality of tanks, there are positive electrodes 27 provided on both surfaces of the resin via the plating bath 28, and uniform plating can be applied to both surfaces of the resin.

(Decomposition of resin: heat treatment)
The aluminum covering resin molding which has a resin molding as a core of a skeleton by the above process is obtained. Next, the base resin is removed. The aluminum-coated resin molded body is heat-treated at a temperature of 500 ° C. or higher and 640 ° C. or lower to decompose the resin molded body and conductive carbon. When heat treatment is performed in the presence of oxygen, the urethane decomposition reaction easily proceeds, and the conductive carbon can be decomposed well. It is preferable to perform the heat treatment while flowing the gas because the decomposition products are efficiently removed.

(Lithium ion battery)
Next, a battery electrode material and a battery using an aluminum structure will be described. For example, when used for a positive electrode of a lithium ion battery, lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium nickelate (LiNiO ₂ ), or the like is used as an active material. The active material is used in combination with a conductive additive and a binder. Conventional positive electrode materials for lithium ion batteries have an active material coated on the surface of an aluminum foil. In order to improve the battery capacity per unit area, the coating thickness of the active material is increased. In order to effectively use the active material, the aluminum foil and the active material need to be in electrical contact with each other, so that the active material is used in combination with a conductive additive. In contrast, the aluminum structure of the present invention has a high porosity and a large surface area per unit area. Therefore, even when an active material is thinly supported on the surface of the aluminum structure, the active material can be used effectively, the capacity of the battery can be improved, and the mixing amount of the conductive assistant can be reduced. A lithium ion battery uses the above positive electrode material as a positive electrode, graphite as the negative electrode, and organic electrolyte as the electrolyte. Since such a lithium ion battery can improve capacity even with a small electrode area, the energy density of the battery can be made higher than that of a conventional lithium ion battery.

(Molten salt battery)
The aluminum structure 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 a cation of a molten salt serving as an electrolyte, such as sodium chromate (NaCrO ₂ ) or titanium disulfide (TiS ₂ ) as an active material. use. 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 chromate is used as the active material and acetylene black is used as the conductive aid, PTFE is preferable because both can be firmly fixed.

  The aluminum structure 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. 6 is a schematic cross-sectional view showing an example of a molten salt battery using the above-described 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 structure, a negative electrode 122 carrying a negative electrode active material on the surface of the aluminum skeleton part of the aluminum structure, 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 evenly. 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 KFSA and NaFSA are used in combination, the operating temperature of the battery can be made 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 resin, etc. can be used. 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.

(Electric double layer capacitor)
The aluminum structure can also be used as an electrode material for an electric double layer capacitor. When the aluminum structure is used as an electrode material for an electric double layer capacitor, activated carbon or the like is used as an electrode active material. Activated carbon is used in combination with a conductive aid and a binder. As the conductive auxiliary agent, graphite, carbon nanotube, etc. can be used. As the binder, polytetrafluoroethylene (PTFE), styrene butadiene rubber or the like can be used.

  FIG. 7 is a schematic cross-sectional view showing an example of an electric double layer capacitor using the above electrode material for electric double layer capacitor. In the organic electrolyte solution 143 partitioned by the separator 142, an electrode material in which an electrode active material is supported on an aluminum structure 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 an aluminum porous body as a current collector, the surface area of the current collector is increased, and an electric double layer capacitor capable of high output and high capacity can be obtained even when activated carbon as an active material is thinly applied. .

  As described above, the case where the foamed resin molded body is used as the resin molded body has been described. However, the present invention is not limited to the foamed resin molded body, and an arbitrary-shaped aluminum structure can be obtained by using a resin molded body having an arbitrary shape. Obtainable.

(Formation of conductive layer: Example 1)
Hereinafter, a production example of the aluminum porous body will be specifically described. As a foamed resin molded body, a urethane foam having a thickness of 1 mm, a porosity of 95%, and a pore number of about 20 per 1 cm was prepared and cut into 15 mm × 15 mm squares. By immersing the urethane foam in a carbon suspension and drying, a conductive layer having carbon particles attached to the entire surface was formed. The components of the suspension include 80% of conductive carbon black having an average particle size of 0.01 μm, and include a resin binder as a binder, a penetrating agent, an antifoaming agent, and a dispersion medium.

(Formation of conductive layer: Comparative Example 1)
As a foamed resin molded body, a urethane foam having a thickness of 1 mm, a porosity of 95%, and a pore number of about 20 per 1 cm was prepared and cut into 15 mm × 15 mm squares. By immersing the urethane foam in a carbon suspension and drying, a conductive layer having carbon particles attached to the entire surface was formed. The components of the suspension include 80% of graphite having an average particle diameter of 1.5 μm, and include a resin binder as a binder, a penetrating agent, an antifoaming agent, and a dispersion medium.

(Formation of conductive layer: Comparative Example 2)
As a foamed resin molded body, a urethane foam having a thickness of 1 mm, a porosity of 95%, and a pore number of about 20 per 1 cm was prepared and cut into 15 mm × 15 mm squares. By immersing the urethane foam in a carbon suspension and drying, a conductive layer having carbon particles attached to the entire surface was formed. The components of the suspension include 80% graphite having an average particle diameter of 1.0 μm, and include a resin binder as a binder, a penetrating agent, an antifoaming agent, and a dispersion medium.

(Molten salt plating)
After setting the urethane foam produced in Example 1, Comparative Example 1 and Comparative Example 2 having a conductive layer on the surface to a jig having a power feeding function, a molten salt aluminum plating bath (67 mol% AlCl at a temperature of 40 ° C. I was immersed in a _{3 -33mol%} EMIC). A jig in which urethane foam was set was connected to the cathode side of the rectifier, and a counter aluminum plate (purity 99.99%) was connected to the anode side. Plating was performed at a current density of 3.6 A / dm ² for 90 minutes. Here, the current density is calculated based on the apparent area of the urethane foam. As a result, an aluminum plating layer having a weight of 150 g / m ² could be formed.

(Disassembly of foamed resin molding)
The foamed resin on which the aluminum plating layer was formed was heat-treated at a temperature in the air atmosphere of 600 ° C. for 30 minutes to obtain the aluminum structures of Example 1, Comparative Example 1, and Comparative Example 2. About each aluminum structure, the carbon residual amount was measured by the high frequency combustion infrared absorption method. The carbon residual amount of the aluminum structure of Example 1 was as low as 1.3% (2.0 g / m ² ), but the carbon residual amount of Comparative Example 1 was 5.5% (8.2 g / m ² ). The carbon residual amount of Comparative Example 2 was 3.0% (4.5 g / m ² ).

The above description includes the following features.
(Appendix 1)
An electrode material in which an active material is supported on the aluminum surface of an aluminum structure obtained by the present invention.
(Appendix 2)
A battery using the electrode material according to Appendix 1 for one or both of a positive electrode and a negative electrode.
(Appendix 3)
An electric double layer capacitor using the electrode material according to appendix 1 as an electrode.
(Appendix 4)
The filtration filter which consists of an aluminum structure obtained by this invention.
(Appendix 5)
A catalyst carrier having a catalyst supported on the surface of an aluminum structure obtained by the present invention.

  As described above, according to the present invention, since a porous aluminum structure can be obtained, the characteristics of aluminum can be utilized in, for example, electric materials such as battery electrodes, filters for various filtrations, catalyst carriers, and the like. Can be widely applied to.

DESCRIPTION OF SYMBOLS 1 Foamed resin 2 Conductive layer 3 Aluminum plating layer 11 Band-shaped resin 12 Supply bobbin 13 Deflector roll 14 Suspension 15 Tank 16 Hot air nozzle 17 Drawing roll 18 Winding bobbin 21a, 21b Plating tank 22 Band-shaped resin 23, 28 Plating bath 24 Cylinder Electrode 25, 27 Positive electrode 26 Electrode roller 121 Positive electrode 122 Negative electrode 123 Separator 124 Holding plate 125 Spring 126 Press member 127 Case 128 Positive electrode terminal 129 Negative electrode terminal 130 Lead wire 141 Polarized electrode 142 Separator 143 Organic electrolyte 144 Lead wire 145 Case

Claims (6)

A conductive step of applying a conductive paint containing conductive carbon to the surface of the resin molded body to make the resin molded body conductive,
A plating step of plating aluminum in a molten salt to form an aluminum layer on the surface of the resin molded body made conductive;
A heat treatment step of removing the resin molded body by heat treatment, comprising:
The method for producing an aluminum structure, wherein the conductive carbon is carbon black having an average particle size of 0.003 μm or more and 0.05 μm or less.   The method for manufacturing an aluminum structure according to claim 1, wherein the heat treatment step is performed in an atmosphere containing oxygen at a temperature of 500 ° C or higher and 640 ° C or lower.   The method for producing an aluminum structure according to claim 1 or 2, wherein the resin molded body is a porous resin body having a three-dimensional network structure.   The said resin molding consists of urethane, The manufacturing method of the aluminum structure of any one of Claims 1-3 characterized by the above-mentioned.   The aluminum structure manufactured by the manufacturing method of any one of Claims 1-4.   The aluminum structure according to claim 5, wherein the carbon content is 2% or less.