JP3413662B2 - Method for producing porous aluminum body - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum porous body for a lithium battery electrode material, which has a three-dimensional network structure having an internal communication space, and at least the surface of this three-dimensional network grid is made of metallic aluminum. It relates to a method of manufacturing.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
As a porous metal body having a three-dimensional network structure having an internal communication space, a porous body made of nickel or copper is known (Japanese Patent Laid-Open No. Sho 5).
5-69285, JP-A-3-30259).

Of these, the former JP-A-55-69285
The method for producing a metal porous body (porous metal foil) described in Japanese Patent Publication No.
Conductivity is imparted to this, and further, a metal is electrolytically deposited on the surface thereof, and if necessary, the above-mentioned support layer is removed by melting or thermal decomposition.

Further, in the method described in JP-A-3-30259, an open cell pyrolyzable foam structure is charged into an atmosphere containing nickel carbonyl gas, and the nickel carbonyl gas is thermally decomposed. A nickel-plated foam structure is formed and then the pyrolyzable foam structure is removed by sintering and thermal decomposition.

The inventors of the present invention have focused on inexpensive aluminum and studied aluminum porous bodies different from these nickel and copper porous bodies, but it is difficult to obtain an aluminum porous body by the conventional method as described above. Met.

That is, when aluminum is plated,
Nickel plating or copper plating should be electrodeposited in an aqueous solution system, whereas electrodeposition should be performed in a non-aqueous solvent system, which makes the equipment complicated and expensive, and causes problems in the working environment. However, it is difficult to adopt it in production technology, and therefore the conventional method of JP-A-55-69285 is not suitable for obtaining a porous aluminum body.

On the other hand, the method disclosed in JP-A-3-30259 is a peculiar method for obtaining a nickel porous body and cannot be adopted as a method for obtaining an aluminum porous body.

[0008]

In view of the above circumstances, the present inventor has conducted various studies on a method for easily and reliably producing an aluminum porous body having a three-dimensional network structure having an internal communication space. In particular, it has been found that by adopting the arc ion plating method, it is possible to efficiently manufacture an aluminum porous body in which a high-strength metallic aluminum layer is uniformly vapor-deposited on the entire lattice surface of a three-dimensional reticulated plastic substrate having an internal communication space. .

That is, when an aluminum layer is obtained by forming and coating an aluminum layer on the lattice surface of a three-dimensional reticulated plastic substrate having such an internal communication space (hereinafter sometimes abbreviated as reticulated plastic substrate), The aluminum layer needs to be uniformly formed and covered from the surface portion of the reticulated plastic substrate to the lattice extending from the innermost portion.

In this case, various methods are known as vapor phase plating methods for aluminum, but in many cases, if the reticulated plastic substrate is relatively thin, aluminum vapor or ions reach the deepest part of the substrate. Although the aluminum film is formed by using this method, if the base becomes thicker, it may be difficult to uniformly form the aluminum film on the lattice surface at the innermost part of the base.

However, when the arc ion plating method is adopted, there is no such disadvantage, and even when the reticulated plastic substrate has a relatively large thickness of about 2 to 10 mm, the lattice surface at the innermost portion of the substrate is uniform. Nikatsu several μm
An aluminum film is formed with a thickness of ten and several μm.

More specifically, the arc ion plating method is a method of evaporating a metal target (cathode) by arc discharge in vacuum to coat the surface of the object to be treated with a metal film. In this method, Since the whole cathode is kept in a solid state, the cathode can be arranged at any place in the plating apparatus (vacuum chamber), and in this case, a plurality of cathodes can be arranged at desired places. Can be formed into a desired shape such as a round bar, and the cathode acts so as to evaporate metal vapor from the entire surface. Therefore, the location of the aluminum cathode and the shape of the aluminum cathode are selected so that the aluminum is randomly generated from the cathode. Foam with a thickness of about 2 to 10 mm as an object to be processed by evaporating in a three-dimensional or three-dimensional manner The present inventors have found that even when a reticulated plastic substrate such as plastic or non-woven plastic fiber is used, the metal aluminum layer is uniformly deposited not only on the lattice surface of the substrate surface but also on the lattice surface at the innermost part of the substrate. Is a finding.

Further, in such an aluminum porous body, the aluminum layer is required to be thick to some extent in order to effectively exhibit the effect of aluminum. Particularly, after the aluminum layer is formed on the reticulated plastic substrate, the substrate is formed. When forming a porous aluminum body in which the lattice is made of only aluminum, the thickness of several μm or more is required from the viewpoint of strength in use.

In this case, in the ordinary vapor-phase plating method, it is necessary to repeat the treatment several times to obtain a thickness of several μm or more. However, according to the arc ion plating method, the above-mentioned treatment method is used. With the above process, it is possible to form an aluminum layer having a thickness of several μm or more even on the innermost lattice of the reticulated plastic substrate having a relatively thick thickness of about 2 to 10 mm. As described above, a thick aluminum layer can be uniformly formed, and the deposition rate is fast. Therefore, the arc ion plating method can easily and reliably form a uniform and thick aluminum layer on the entire lattice surface of the reticulated plastic substrate. It has been found that this is possible and therefore this arc ion plating method can be used very effectively in the production of porous aluminum.

Surprisingly, the aluminum layer formed by this arc ion plating method has good adhesion to the material and has the highest strength, and it is sufficient even if the reticulated plastic substrate is removed. It was found that it has various strengths.

The aluminum porous body thus obtained is in a state where the aluminum layer is formed on and covered with the reticulated plastic substrate, or the substrate is removed by a method such as thermal decomposition or chemical dissolution. In this case, since the aluminum layer by the arc ion plating method has a rough surface, it has very good retention and adhesion to the supported substance, especially the material for battery electrodes. Found to be suitable for use as
The present invention has been completed.

Therefore, the present invention relates to a method for producing an aluminum porous body for an electrode material of a lithium battery, which comprises subjecting a three-dimensional mesh plastic substrate having an internal communication space to a vapor deposition of aluminum by an arc ion plating method, A method for producing an aluminum porous body, which comprises forming a metal aluminum layer having a thickness of 2 to 20 μm by covering the surface of a three-dimensional net-like lattice extending from the surface portion to the innermost portion of the substrate, and an internal communication space. A three-dimensional reticulated plastic substrate having the above is subjected to a vapor deposition of aluminum by an arc ion plating method to cover the surface of the whole three-dimensional reticulated lattice from the surface portion to the innermost portion of the substrate, and 2 to 20
There is provided a method for producing an aluminum porous body, which comprises forming a metallic aluminum layer of μm and then removing the substrate to obtain an aluminum porous body comprising a three-dimensional mesh lattice of metallic aluminum.

The present invention will be described in more detail below.
In the present invention, the plastic substrate used for producing the aluminum porous body has a three-dimensional network structure having an internal communication space, and examples thereof include foamed plastic, plastic fiber nonwoven fabric, and the like. Of course, it is not limited to these. The foamed plastic may be any as long as it has an open cell structure, but it is preferable that it does not have a cell membrane and is substantially composed only of a skeleton lattice. For example, polyurethane foam with the cell membrane removed is preferably used,
Open-cell foams of polystyrene, polyvinyl chloride, polyethylene, polyisocyanurate, polyphenol, polypropylene and the like are also preferably used. As the plastic fiber nonwoven fabric, various plastic fiber nonwoven fabrics such as polypropylene and polyester can be used.

In this case, the properties of the reticulated plastic substrate are variously selected according to the application of the porous aluminum body, but it is generally preferable that the average pore diameter is about 100 μm or more. Further, the thickness is usually 2 to 10 mm, and according to the arc ion plating method, even when a substrate having a small average pore diameter and a small porosity and a relatively thick thickness is used, the lattice surface at the innermost portion is Also, the aluminum layer can be formed well.

According to the present invention, aluminum is vapor-deposited on the reticulated plastic substrate by adopting the arc ion plating method. Therefore, it is possible to form and coat an aluminum layer on the surface of the whole lattice from the surface part of the reticulated plastic substrate having a relatively large thickness to the innermost part at a high deposition rate with a uniform and thick film thickness on the plastic substrate with good adhesion. it can.

Here, the arc ion plating method is one in which aluminum is evaporated as a target (cathode) by arc discharge in vacuum as described above, and metallic aluminum is vapor-deposited on a reticulated plastic substrate. As the method, the method described in JP-B-62-5228 can be adopted.

FIG. 1 shows an example of an apparatus for depositing aluminum on a reticulated plastic substrate by the arc ion plating method. In the figure, 1 is a reactor (vacuum chamber), 2 is an aluminum connected to an arc power source 3. Targets (cathodes) 4 are turntables connected to a bias power source 5, and a reticulated plastic substrate 6 is placed on the turntable 4 and the aluminum target 2 is used.
The more evaporated aluminum vapor is deposited on the reticulated plastic substrate 6. In the figure, 7 is a gas inlet,
Although 8 is an exhaust port, the gas introduction port 7 is not essential in the present invention.

In this case, the position and shape of the aluminum target 2 are selected so that the aluminum target 2 can be vapor-deposited on the substrate 6 in a random or three-dimensional manner. For example, the target 2 is formed in the shape of a round bar or the like. It can be arranged so as to surround the substrate 6.

FIGS. 2 and 3 show an example in which aluminum is continuously vapor-deposited on the substrate 6. The substrate 6 held in a roll is continuously fed out, and the aluminum is continuously vapor-deposited at the point A. Then, the aluminum vapor-deposited substrate is rewound.

Here, the conditions of arc ion plating
The condition can be appropriately selected, but the degree of vacuum is 10^-3 ~ 1
0^-Four Torr, typically an arc current of about 100 AH,
The bias voltage can be about 30V.

In the present invention, it is preferable to form an aluminum layer of 2 to 20 μm, especially 8 to 12 μm on the whole lattice surface of the reticulated plastic substrate by the arc ion plating method.

The thus-obtained aluminum porous body of the present invention can be used as it is, that is, with the aluminum layer formed on the lattice surface of the reticulated plastic substrate, but the reticulated plastic substrate may be removed if necessary. It can be used as an aluminum porous body having a lattice made of only aluminum, that is, an aluminum porous body made of only aluminum having the same lattice mode as the reticulated plastic substrate.

In this case, the method for removing the reticulated plastic substrate can be appropriately selected according to the type of plastic (melting temperature or thermal decomposition temperature, chemical solubility, etc.),
For example, a method of removing the plastic substrate by melting or thermal decomposition, a method of dissolving the plastic with an appropriate organic solvent, and the like are adopted. Here, when the plastic is dissolved in an appropriate organic solvent, a certain amount of pinholes are required in the aluminum layer covering the lattice surface of the substrate. Therefore, after forming the aluminum layer thinly, the plastic is dissolved in the organic solvent. It can be dissolved and removed, and then vapor deposition is again performed by the arc ion plating method to obtain a predetermined film thickness.

The aluminum porous body obtained according to the present invention is lightweight, has high corrosion resistance, and is inexpensive, so that it is used as an electrode of a battery for carrying lithium and alloying with lithium in a lithium battery. It can be used as a material.

[0030]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[Example 1] Aluminum was vapor-deposited on a plate-shaped polyurethane foam having a thickness of 2 mm and 80 holes / inch by an arc ion plating method. In this case, the condition of arc ion plating is vacuum degree 1
The treatment was performed for 20 minutes under the conditions of 0 ⁻⁴ Torr and an arc current of 100 AH.

As a result, it was confirmed that an aluminum film having a thickness of about 10 μm was formed up to the innermost part so as to cover the entire lattice surface of the polyurethane foam.

[Example 2] Porosity 15%, thickness 1.5 m
Aluminum vapor deposition is performed on the polypropylene fiber nonwoven fabric of m by the arc ion plating method in the same manner as in Example 1. Approximately 10 μm covering the whole lattice surface of the non-woven fabric
Of aluminum film was formed.

Next, this aluminum vapor-deposited non-woven fabric is used for 15
The mixture was left in a heating furnace at 0 ° C. for 10 minutes to melt and remove most of the polypropylene fibers, and further left for 5 minutes in a heating furnace kept in a slightly oxidizing atmosphere at 250 ° C. to oxidize and remove the remaining polypropylene. An aluminum plate made of only aluminum in the same lattice mode as the non-woven fabric was manufactured.

Example 3 A polyester nonwoven fabric (fiber diameter: about 12 μm, thickness: 0.1 mm, weight: 36 g / m ² ) was subjected to an arc-based ion plating method and a vacuum deposition method (eramet method), respectively. A metal aluminum layer was formed under the following conditions.

Arc ion plating method Vacuum degree 10 ⁻⁴ Torr Arc current 100 AH Treatment time 20 minutes

Vacuum deposition method Degree of vacuum 1.5 × 10 ⁻⁴ Torr Processing time 20 minutes

Micrographs of the metallic aluminum layer obtained above are shown in FIGS. Here, FIG. 4 is a 790-times micrograph of a polyester nonwoven fabric, FIGS. 5 and 6 show a metal aluminum layer by an arc ion plating method, FIG. 5 is a 790-times micrograph, and FIG. 6 is a 4000-times micrograph. It is a 790 times microscope photograph of the metal aluminum layer by a vacuum evaporation method.

As can be seen from FIGS. 4 to 7, the deposition rate of aluminum in the arc ion plating method is considerably higher than that in the vacuum deposition method (as is clear from FIGS. 4, 5 and 7, microscopic photographs at the same magnification are shown. The arc ion plating method of FIG. 5 is very thick). Actually, the surface resistance of the deposited aluminum by the arc ion plating method and the vacuum deposition method is 1.08 × 10 ^-2 Ω / cm ² ,
The latter was 4.07 × 10 ⁻² Ω / cm ² . Note that this comparison shows the magnitude of the deposited aluminum film thickness based on the difference in the deposition rate, but the film formed by the arc ion plating method is dense, and even if the same film thickness is compared, it is obtained by the arc ion plating method. The surface resistance of the aluminum film was lower than that by the vacuum deposition method.

Further, the adhesion between the deposited aluminum and the polyester nonwoven fabric by the arc ion plating method and the vacuum vapor deposition method was carried out as follows. As a result, the aluminum film by the arc ion plating method had good adhesion to the material. It was a thing.

(1) Bending test Under the conditions of Example 3, the arc type ion plating method and the vacuum vapor deposition method (eramet method) were applied to a polyester nonwoven fabric.
The 180 ° bending test was repeated 10 times (total 20 times) on the test piece coated with metallic aluminum according to, and the degree of adhesion between the coated aluminum and the nonwoven fabric at the bent portion was compared. As a result, the test piece produced by the arc ion plating method hardly separated aluminum from the nonwoven fabric, whereas the test piece produced by the vacuum deposition method partly separated into aluminum powder.

(2) Tape test For the test piece coated with metallic aluminum and the non-woven fabric material under the conditions of Example 3, 90 with a commercially available cellophane tape.
The tape test was conducted at a temperature of 50 ° C. to compare the amount of fibrous deposits on the tape with the amount of aluminum powder deposits (× 40 magnifying glass). The results are shown in Table 1.

[0043]

[Table 1]

[Application Example] Application Example as Material for Electrode of Lithium Battery Positive electrode in which the positive electrode active material (manganese dioxide, cobalt oxide, titanium sulfide, etc.) is filled in the electrode support made of the porous aluminum of Example 3. And a battery made of a non-aqueous electrolyte using an electrode mainly composed of lithium as a negative electrode, and the same positive electrode active material and a conductor (graphite, carbon) on an electrode substrate using a conventional stainless thin plate or aluminum thin plate. Etc.), using a positive electrode coated with a material kneaded with a binder that binds these, on the other hand, when compared with a battery composed of the same non-aqueous electrolyte using the same lithium electrode as the negative electrode , Discharge electric capacity (WH) 115%,
The electrical output (W) was 122%, and the products according to the present invention showed excellent characteristics.

[0045]

[0046]

According to the present invention, it is possible to form a uniform, thick and strong aluminum layer covering the entire lattice surface of the reticulated plastic substrate, and it is possible to easily and reliably produce a porous aluminum body efficiently. .

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of an arc ion plating apparatus used for carrying out the present invention.

FIG. 2 is a schematic perspective view illustrating an example of a method for continuously processing a reticulated plastic substrate.

FIG. 3 is a schematic perspective view illustrating another example of a method for continuously treating a reticulated plastic substrate.

FIG. 4 is a micrograph (× 790) showing the shape of fibers of a polyester nonwoven fabric.

FIG. 5 is a micrograph (× 790) showing a fiber shape of a polyester nonwoven fabric having an aluminum layer formed by an arc ion plating method.

FIG. 6 is a micrograph (× 4000) showing a fiber shape of a polyester nonwoven fabric having an aluminum layer formed by an arc ion plating method.

FIG. 7 is a micrograph (× 7) showing the fiber shape of a polyester non-woven fabric having an aluminum layer formed by a vacuum deposition method.
90).

[Explanation of symbols]

1 Reactor (vacuum chamber) 2 Aluminum target (cathode) 3 arc power supply 4 turntable 5 Bias power supply 6 reticulated plastic substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-69334 (JP, A) JP-A-60-223029 (JP, A) JP-A-4-2795 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C22C 1/08 C23C 14/20

Claims (3)

(57) [Claims] 1. A method for producing an aluminum porous body for an electrode material of a lithium battery, which comprises subjecting a three-dimensional reticulated plastic substrate having an internal communication space to vapor deposition of aluminum by an arc ion plating method, A method for producing a porous aluminum body, comprising forming a metallic aluminum layer of 2 to 20 μm by covering the surface of the whole three-dimensional mesh lattice from the surface portion to the innermost portion. 2. A method for manufacturing an aluminum porous body for an electrode material of a lithium battery, which comprises subjecting a three-dimensional mesh plastic substrate having an internal communication space to a vapor deposition of aluminum by an arc ion plating method, A metal aluminum layer having a thickness of 2 to 20 μm is formed by covering the surface of the entire three-dimensional reticulated lattice from the surface portion to the innermost portion, and then the above-mentioned substrate is removed to form an aluminum porous layer made of a three-dimensional reticulated lattice of metallic aluminum A method for producing a porous aluminum body, which comprises obtaining a body. 3. The plastic substrate has a thickness of 2 to 10 mm.
The manufacturing method according to claim 1 or 2.