JPH08222226A - Manufacture of three-dimensional mesh electrode carrier - Google Patents

Abstract

PURPOSE: To provide an electrode carrier with large porosity and mechanical strength. CONSTITUTION: After the skeletal surface of a porous resin core is covered with the first metal in a method of electroless plating, vacuum deposition or sputtering, it is impregnated and coated with slurry mainly containing the second metal powder and organic binder. Then, in a non-oxidizing atmosphere, heating is applied at a certain or higher temperature where the first metal and the second metal powders are sintered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a three-dimensional network structure electrode carrier, particularly an electrode carrier used as an electrode substrate for alkaline secondary batteries such as nickel-cadmium batteries, nickel-hydrogen batteries and nickel-zinc batteries. Regarding the method.

[0002]

2. Description of the Related Art A method for producing a porous metal body having a three-dimensional network structure having communicating holes includes a plating method such as JP-A-57-174484 and a sintering method such as JP-B-38-17554. There is something. In the plating method, carbon powder is applied to the skeleton surface of foamed resin such as urethane foam to conduct conductivity, and the metal is electrodeposited by electroplating, and then the foamed resin and carbon are burned off. It is a method of obtaining a porous body. With this method, the properties such as strength required for the porous metal body can be satisfied, but the manufacturing process is complicated, resulting in high cost.

On the other hand, in the method for producing a metal porous body by the sintering method described in Japanese Examined Patent Publication No. 38-17554, slurry metal powder is impregnated and applied on the skeleton surface of a foamed resin such as urethane foam, and then dried and heated. Describes a method of sintering metal powder. However, according to the knowledge of the present inventors, in this method manufactured without any special device, since the strength as a metal porous body is weak, it is necessary to bend the electrode plate or various filters when actually used. There was a problem that it could not withstand processing such as processing. Further, when it was directly applied onto the porous resin, the wettability with respect to the slurry was poor and there were many coating defects. For this reason, it remains as a skeleton defect portion even after sintering, and the electric resistance becomes high, so that the characteristics are not sufficient as an electrode carrier.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a new finding in order to solve the problems such as the need for complicated manufacturing steps as in the above conventional example and the addition of strength necessary for use as a battery electrode. The present invention is intended to provide a method for manufacturing a three-dimensional network structure electrode carrier based on.

[0005]

DISCLOSURE OF THE INVENTION As a result of studying the above-mentioned problems, the present invention has revealed that the skeleton surface of the porous resin core is electroless plated or vacuum-deposited before the dip coating of the slurry containing the metal powder. It was discovered that the above problems can be solved by coating the metal with any one of the sputtering methods. That is, the structure of the present invention, after coating the first metal on the skeleton surface of the porous resin core body by any one of the electroless plating method, the vacuum deposition method, and the sputtering method,
Third-order in which a slurry containing a second metal powder and an organic binder as a main component is impregnated and applied, and then heated in a non-oxidizing atmosphere to a temperature at which the first metal and the second metal are sintered or higher. This is a method for manufacturing an original reticulated structure electrode carrier.

Further, the second metal powder is Ni. Al, B, Bi, Ga, G whose melting point is lowered by alloying the first metal with Ni or Cu as a main component
e, In, Mg, P, Sn, Zn, any one or two or more metal alloy, porous resin core is foamed resin, resin fiber felt, non-woven fabric and woven fabric The method for producing a three-dimensional net-structured electrode carrier is configured to be any one of the above. Further, the coated first metal has a function of promoting sintering with the second metal adjacent to the coating film during heat treatment. For example,
In the case of using only Ni powder without coating the first metal, in order to maintain the skeleton structure of the porous body, sintering by solid phase diffusion at a temperature below the melting point of Ni is used. In the invention, since the sintering is performed by the liquid phase diffusion utilizing the lowering of the melting point by the liquid phase reaction between the additive metal contained in the first metal and Ni, the sinterability is extremely good, and as a result, sufficient strength characteristics are obtained. A metal porous body having is obtained.

Here, Ni or C is used as the first metal.
u as a main component, Al, B, Bi, Ga, Ge, In,
It is possible to use an alloy composed of one or more additive metals selected from Mg, P, Sn, and Zn. Further, the content of these metals is preferably 0.1 to 10 wt%. If it is less than 0.1 wt%, a sufficient sintering promoting effect cannot be obtained. If it exceeds 10 wt%, the sintering promoting effect is great, but the solid solution or intermetallic compound formation on the Ni or Cu skeleton of the final product may occur. This is because, as it progresses, it may lead to embrittlement or increase in electrical resistance. In the step of producing the slurry liquid of the present invention, the above metal mixed powder and a binder agent such as an acrylic resin are sufficiently dispersed and mixed with a dispersant such as carboxymethyl cellulose and a solvent such as water in a mixer such as a ball mill. It can be realized by Next, this slurry liquid is applied to a synthetic resin porous body having a three-dimensional network structure having communicating holes, such as polyurethane foam, and then dried. This coating is heat-treated in a reducing atmosphere such as a hydrogen stream to remove organic components such as polyurethane foam and sinter the metal powder, and finally have a three-dimensional network structure having communicating holes. A metallic porous body is obtained. Note that instead of hydrogen, N ₂ , Ar
Similar results can be obtained using gas.

[0008]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 1) Preparation of metal powder slurry 60 wt% of nickel powder (type 255 manufactured by Inco Co., Ltd. average particle size 2.5 μm), carboxymethyl cellulose resin 2 wt%, phenol resin 10 wt%, water 28
It was prepared by mixing with a ball mill at a blending amount of wt%. 2) Metallic coating of porous resin core As the resin core, there are about 50 pores per inch, average pore diameter 300 μm, porosity 96%, thickness 1.8 mm, width 20 cm, length 1 m polyurethane foam. This polyurethane foam was coated with 10 g / m ² of nickel metal as the first metal on the entire three-dimensional network skeleton by a conventional electroless plating method. The P content was 0.5 wt%.

3) Impregnation of Slurry Next, a urethane foam coated with metal was dipped in a slurry liquid prepared in advance and impregnated and coated on the polyurethane foam by a method of removing excess paste by a roll. The applied amount was 600 g / m ² in terms of metal amount. 4) Heating in non-oxidizing atmosphere The resin core body obtained through the above step 3) was dried at 120 ° C for 10 minutes in a nitrogen atmosphere. Then, in a hydrogen stream at 30 ° C /
The temperature is raised to 1150 ° C at a heating rate of 1 minute, and at 1150 ° C, 1
By heat treatment for 0 minutes, a porous metal body having a three-dimensional network structure was obtained. 5) Product Properties As mechanical properties, a tensile strength of 4 kg / 15 mm width, an elongation rate of 4%, and an electrical resistance of 55 mΩ / 10 mm width / length 10 cm were obtained. The properties which can be sufficiently used for the metal porous body used for the battery electrode plate were obtained.

Example 2 A slurry-coated material was prepared in the same manner as in Example 1 except that electrolytic copper powder having an average particle size of 20 μm and a maximum particle size of 50 μm was slurried. Then, the coated article is dried at 120 ° C. for 10 minutes in a nitrogen atmosphere, then heated to 1000 ° C. at a heating rate of 50 ° C./minute in a hydrogen stream, and heated at 1000 ° C. for 10 minutes to form a three-dimensional network structure. The electrode carrier of was obtained. Comparative Example 1 and Comparative Example 2 Table 1 also shows the properties of the metal porous body produced by the same method as in Example 1 using urethane foam not subjected to the metal undercoating treatment. Mechanical property is 15mm width, electric resistance is 1
It was measured with a width of 0 mm and a length of 10 cm. Table 1 shows the mechanical characteristics and the electrical resistance measurement results of the three-dimensional net-structured electrode carriers obtained in Examples 1 and 2 and Comparative Examples 1 and 2.

[0011]

[Table 1]

Comparative Example 1 in which Example 1 or Example 2 in which electroless nickel plating was applied as a base treatment was not applied
Alternatively, as compared with Comparative Example 2, good mechanical properties and electrical properties sufficiently obtainable for a metal body used for a battery electrode plate were obtained. Further, in Comparative Examples 1 and 2, uniform slurry coating was not carried out on the entire skeleton surface of the urethane coating after slurry coating, and many coating defects were observed. It was found that this coating defect location remained as a sintering defect in the final product as well. This defect is the cause of low mechanical strength and high resistance.

Example 3 1) Preparation of metal powder slurry 50 wt% of nickel powder (type 123 made by Ink Co., Ltd. average particle size 5.2 μm), 2 wt% of carboxymethyl cellulose resin, 10 wt% of acrylic resin, 28 w of water
A ball mill was mixed at a blending amount of t%. 2) For the metal target, 1 wt% of metal Bi powder of -350 mesh, 0.2 wt% of lubricant and the rest are nickel powder type 123 powder manufactured by Inco Co., blended, and then mixed in a ball mill for 5 hours, and then an embossing press. Then, it was used as a metal powder target.

3) Metal coating of the porous resin core body: Preliminarily left in a vacuum of 10 ^-2 Torr for 2 hours for cleaning the surface of the urethane foam skeleton, and after removing water and volatile components attached to the surface, A urethane foam was set in a normal roll-up type vacuum deposition device. The metal powder target in the crucible was irradiated with an electron beam having an output of 2 kW to melt and evaporate the metal, and the skeleton surface of the urethane foam was coated with a metal so that the average weight of the metal was 5 g / m ² . 4) Impregnation of Slurry Next, the metal-coated urethane foam was dipped in a slurry liquid prepared in advance, and the polyurethane foam was impregnated and coated by a method of removing excess paste by a roll. The applied amount was 600 g / m ² in terms of metal amount.

5) Heating in non-oxidizing atmosphere After coating the prepared metal slurry on the surface of the skeleton, 120
It was dried at 0 ° C for 10 minutes. Then, the coating is heated to 1050 ° C. at a heating rate of 60 ° C./min in a steam flow and heated to 10 ° C.
A heat treatment at 50 ° C. for 10 minutes gave an electrode carrier having a three-dimensional network structure. 6) Properties of products As mechanical properties, tensile strength is 5.5 kg / 15 mm width,
Elongation rate 5%, electric resistance 60mΩ / 10mm width / length 10
cm was obtained. In mechanical properties as compared with Example 1,
It was found that the characteristics were improved more than those using the metal-coated product by electroless plating, and the same characteristics were obtained at low temperature.

Comparative Example 3 A three-dimensional net-structured metal porous body was produced in the same manner as in Example 2 by using urethane foam coated with nickel powder slurry without coating the metal base. The heat treatment temperature in hydrogen was 1200 ° C. for 10 minutes. The mechanical properties and electrical properties were measured under the same conditions as in Example 1. Mechanical properties include tensile strength 0.8kg / 15mm width, elongation 1.1%,
An electrical resistance of 240 mΩ / 10 mm width and length 10 cm was obtained. Despite being heat-treated at a higher temperature than Comparative Example 3 in which a metal undercoating was performed, Comparative Example 3 in which the undercoating was not performed was inferior in mechanical properties and electrical properties. Was found to improve.

Comparative Example 4 A urethane foam was coated with a Bi-added Ni alloy in the same manner as in Example 3 to prepare a metal porous body. The composition of the metal target was Bi 6 wt% and the balance was Ni. As mechanical properties, a tensile strength of 8 kg / 15 mm width, an elongation rate of 1.5%, and an electrical resistance of 180 mΩ / 10 mm width / length 10 cm were obtained. It was found that in Comparative Example 3 in which the undercoating was not performed as compared with Example 3 in which the metal undercoating was performed, the tensile strength was improved, but the electrical characteristics were poor and it was unsuitable for use as a battery electrode.

Examples 4 to 19 and Comparative Examples 5 to 12 As in Example 3, metal coating was performed by using the vacuum deposition method. As the target for the coated metal, Al, B, Ga,
An alloy target of a metal selected from the metals of Ge, In, Mg, Sn and Zn and Ni was used. The composition of the alloy target is shown in Table 2. The coating treatment was constant at 5 g / m ² . After the metal coating treatment, the same slurry as that produced in Example 1 was applied, and heat treatment was performed under the heat treatment conditions shown in Table 2 to obtain a three-dimensional network structure electrode carrier. The properties of the product are shown in Table 3.

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

As described above, according to the method of the present invention, the coating defects of the core are reduced and the sinterability of the powder is improved, so that the mechanical strength of the product is improved and the electric resistance is improved. descend. Therefore, since the power loss due to the electric resistance is small, it is effective as an electrode plate for a large battery. When a metal whose melting point is lower than that of a single metal by being alloyed with Ni or Cu is mixed, the heat treatment temperature for sintering is lowered, and thus the heat treatment cost is lowered. In addition, the solid solution strengthening of the metal improves the mechanical properties of the product over a single metal, for example, pure nickel.

Claims (5)

[Claims] 1. A skeleton surface of a porous resin core is coated with a first metal by any one of an electroless plating method, a vacuum deposition method and a sputtering method, and then a second metal powder and an organic material. Three-dimensional reticulate, characterized in that a slurry containing a binder as a main component is impregnated and coated, and then heated in a non-oxidizing atmosphere to a temperature at which the first metal and the second metal powder are sintered or higher. Method for manufacturing structured electrode carrier. 2. The first metal, which has Ni or Cu as a main component, is alloyed to lower the melting point of Al, B, B.
The three-dimensional net-like structure according to claim 1, which is an alloy composed of one or more additive metals selected from metals of i, Ga, Ge, In, Mg, P, Sn, and Zn. Method for manufacturing structured electrode carrier. 3. The method for producing a three-dimensional network electrode carrier according to claim 1, wherein the second metal powder is Ni or Cu. 4. The first metal contains an additive metal other than Ni or Cu in a range of 0.1 wt% or more and 10 wt% or less, according to any one of claims 1 to 3. A method for manufacturing an electrode carrier having a three-dimensional network structure. 5. The tertiary according to claim 1, wherein the porous resin core is any one of foamed resin, felt made of resin fiber, non-woven fabric and woven fabric. Method for producing original network electrode carrier.