JPH11176451A - Metal porous body having inclined structure, and manufacture thereof, and battery board using the metal porous body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimally collect the charge generated by the active material with increase in the surface area of a board by filling the active material in a metal porous body, having a fin which has a mean length at a specified ratio in relation to the cell radius in a framework part of a cell and having a metal filling density to be changed in the thickness direction to form a battery board. SOLUTION: As a raw material for a metal porous body having an inclined structure, a foaming urethane having the inclined structure that a surface area thereof is changed in one way and having the inclined structure that a surface area is large at a central part thereof and the surface area of a surface and back surface are small is used. This metal porous body is formed of a part 4 formed a with only a slight remains cell film, which is not broken by the ultraviolet ray treatment, and a part 5 in which a cell film is left at 20-60% of the initial time, and a part 6, in which the call film is left at 70% of the initial time or more. When this metal porous body is used for battery board, when the part 4, in which only a slight cell film is left, is first charged with an active material for compression, metal cell of the part 6, in which the cell film at 70% or more of the initial time is s left, is broken so as to form a collector. It exhibits effectiveness for capacity maintenance and the like at repeated chargings and dischargings a battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous metal used for a filter, a battery substrate and the like, a method for producing the same, and a battery substrate produced using the porous metal.

[0002]

2. Description of the Related Art There are various industrial means for porous metal bodies, but the main ones are a method of solidifying metal powder and sintering it, and using a resin or a combustible material as a material to add a metal. A method of adding and subsequently removing the resin or combustible material, a method of hardening metal fibers, and the like can be given. In particular, since a high porosity is required for the application, a method of adding a metal to a resin or a combustible material as a raw material and removing the resin or the combustible material later occupies a large share.

[0003] As this means, there are various methods.
Examples of the material include a resin foam, for example, urethane foam, and a resin or carbon fiber used as a nonwoven fabric, to which a metal is added by the following means. a) means for performing electroplating after conducting treatment; b) means for performing electroless plating and further performing electroplating; c) means for performing further electroplating after performing physical vapor deposition plating; d) paint containing metal powder E) means for applying a paste containing a metal compound, and e) means for applying a paste of a paint containing a metal compound, followed by reduction sintering; f) coating a metal or a metal compound by physical or chemical vapor deposition Thereafter, various steps can be taken by means of sintering or reduction sintering, and by combining these unit operations. When using carbon fiber,
Since the material itself has conductivity, a conductive treatment is not particularly required. However, when a resin is used, a conductive treatment is required. In the conductive treatment, carbon or metal powder is attached. Electroless plating is one of the means, and physical vapor deposition is the same. Resin or combustible material can be subjected to electrolytic plating by such a conductive treatment.

As another means, a paste containing a metal powder or a metal compound is applied to a raw material, and the paste is sintered in a furnace in a reducing atmosphere. The metal or metal compound adhering to the material is reduced and the metals are linked to each other to form a porous metal body. Furthermore, means combining plating and metal sintering can be used. These combinations are based on the specifications of the porous metal used,
Judgment is made based on mechanical properties such as spreadability, and electrical properties such as conductivity and current collecting properties.

[0005] The porous metal thus obtained has a high porosity while having the strength, heat resistance, and electrical conductivity of a metal, and is used as a material taking advantage of its characteristics. Recently, a porous metal body made of Ni has been used as a current collecting substrate of a secondary battery called a nickel-cadmium battery or a hydrogen battery. In addition, there is a use as a renewable filter.

[0006] Among the porous metal bodies produced by the above-mentioned many production methods, those which are particularly suitable for use as a battery electrode plate are prepared by subjecting urethane foam to a conductive treatment and then electroplating Ni. , After which the urethane is incinerated and reduced. The strength of the metal skeleton,
By maintaining the urethane foam cell in its original shape, the porosity increases the amount of active material that is a component of the battery and allows it to be incorporated into the pores. It can be said that the structure is suitable for current collection.

The foamed urethane used here is used as a structure having a large porosity and elasticity by foaming a urethane resin, and by removing a cell membrane of the foamed cell, a porous metal is formed. Can be used as body material.

There are various methods for rupture of the urethane foam. Among the methods that are industrially useful, rupture using an explosive gas and explosion energy is often used. In addition, a method using a chemical treatment such as an alkali, a method using pressure of a high-speed fluid, and the like are known.

[0009] A few examples are described in JP-B-43-655.
In Japanese Patent Application Laid-Open No. 4 (1999) -175, there is disclosed, as an example of chemical treatment, a method of immersing urethane foam in water, an alkaline hydroxide, a water-soluble glycol and an aliphatic alcohol to remove a residual film. Japanese Patent Publication No. 45-11717 discloses a method in which concentrated sulfuric acid is dispersed in an inert solvent, and this is brought into contact with urethane foam to perform a membrane breakage treatment. As another means, there is disclosed a means of rupture of a film by an explosion of gas, rather than rupture by contacting a mixed gas of acetylene gas and oxygen with the surface of a polyurethane foam in a flame-like manner (Japanese Patent Publication No. 43-43). No. 16324). Furthermore, in order to further stabilize the means, a method is also disclosed in which urethane foam is first dampened with a nonflammable liquid, and the explosion treatment is performed thereon, thereby reducing the damage of the foam skeleton due to heat. (Japanese Patent Publication 43-13)
395).

[0010] As described above, the rupture of urethane foam is performed by various methods, and the rupture state is a communication hole leaving only a skeleton portion without a film residue. In this,
The film rupture method in the explosion treatment makes use of the original material characteristics of the resin. That is, this is because only the rupture of the film is performed while maintaining the original characteristics of the urethane resin such as mechanical strength and elongation.

However, in the rupture of urethane foam due to the explosion treatment, along with the blast which is the power to rupture the film, heat is generated, and the remaining rupture film remaining in the skeleton of the urethane foam is absorbed into the skeleton by melting by heat. Would. For this reason, sufficient strength can be obtained as a skeleton, and as a result, good and uniform broken urethane foam can be obtained.

[0012]

However, there has been a further demand for use as a battery substrate as described above.
That is, as a battery substrate, it is necessary to increase the surface area of the substrate as much as possible in order to increase the current collecting performance. In order to increase the surface area of the battery substrate, it is necessary to increase the surface area per unit of urethane foam as a material. One solution is to make the cells as fine as possible in the stage of urethane foaming. However, reducing the size of the foam cell has many factors such as selection of the average molecular weight and the degree of branching of the urethane resin, selection of the vaporizing solvent used for foaming,
Also, even if this is true, the rupture of the membrane due to the explosion treatment becomes more difficult due to the small cell diameter. Furthermore, the active material is packed in the metal porous body, and the metal porous body is compressed,
There is a step of eliminating pores remaining between the active material and the porous metal as much as possible. At this time, if the size of the foam cell is reduced, the active material becomes difficult to enter into the cell, which is a problem.However, the thickness of the skeleton becomes thinner in proportion to the diameter of the cell. Is more likely to be performed. The cutting of the skeleton causes a decrease in current collecting properties as a substrate, which is inconvenient.

[0013]

SUMMARY OF THE INVENTION The present invention is directed to a porous metal body having a three-dimensional network structure in which a plurality of cells are combined, wherein the skeleton portion of the cells has an average length of 1% to 25% of the cell radius. The present invention provides a porous metal body having a tilted structure, characterized by having fins having the following characteristics, and wherein the metal packing density changes in the thickness direction. The one having a slope structure in which the packing density of the metal is continuously increased at the center of the thickness,
A porous metal body having a tilted structure in which the packing density of the metal changes in one direction from the surface layer portion to the back surface portion can be obtained. Further, depending on the use condition, the metal inside the skeleton may be different from the skeleton surface portion of the porous metal body.

The production of such a porous metal body is characterized in that the film breakage of the urethane foam used is performed by ultraviolet treatment or ultrasonic treatment. According to these film rupture treatments, the cell film accounts for 1% to 2% of the remaining film close to the skeleton.
5% is left, and the membrane breaks into a fin shape, and the surface area per unit volume of urethane increases only in that portion. And by adjusting the conditions of the rupture, it is possible to leave the cell membrane,
Depending on the processing direction, there are two types: one that leaves unprocessed cell films on one side, and one that leaves many unprocessed cell films in the center in the thickness direction by processing from both sides. There are several to several tens of cell membranes for one cell, and the cell membrane between cells is broken somewhere, and almost all cells are closed. There is no state.

Then, using the urethane foam, a) means for conducting an electroplating treatment after conducting the conductive treatment, b) means for performing an electroless plating treatment and further an electroplating treatment, and Means for plating, d) means for applying and sintering a paint paste containing a metal powder, e) means for applying and applying reduction paste after applying a paint paste containing a metal compound, f) physical or chemical vapor After coating a metal or a metal compound by a phase vapor deposition method, sintering or reduction sintering is used, or a combination thereof is used to form a porous metal body. Further, it is also preferable to add that the film rupture treatment is an ultraviolet treatment, and thereafter any one of physical shock, vibration, and swelling means or a combination thereof is used.

In the porous metal body thus formed, the amount of adhered metal is proportional to the surface area of the urethane foam, and the surface area of the porous metal body is also changed by changing the surface area of the broken urethane foam in the thickness direction. And a tilt structure that changes. The active material is filled in this porous metal body,
When used as a battery substrate, the surface area of the substrate increases,
Further, the structure is convenient for collecting charges generated by the active material.

As one example, when a large amount of metal adheres to one side, there is a method in which the active material is unilaterally packed from the small side, and when the other side is pressed while the active material does not enter much, The holes are crushed, and one side is mostly metal and becomes an electrode plate. If a large amount of metal adheres to the center in the thickness direction of the porous metal body, the active material can be packed from both sides, and the central part where the active material cannot enter much is similarly crushed by compression. , It can be in the state of an electrode plate made of almost only metal. A structure in which a metal plate for current collection is installed on one side or the center and a porous metal body is installed on the opposite side or both sides can be considered, but it is difficult to join the metal plate and the porous metal body, and the connection is made. Resistance increases. On the other hand, the present invention is advantageous in terms of electric resistance because it has a structure in which these can be formed integrally and the amount of metal changes continuously.

[0018]

[Action]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A partially broken urethane foam to be used as a material of the present invention is prepared as follows. First,
Urethane foam that has not been subjected to membrane rupture processing is formed into a sheet or plate. The sheet can be cut into a long shape and rolled and rolled for continuous processing.

Ultraviolet rays or ultrasonic waves are applied to the unbroken urethane foam. In the case of ultraviolet rays, depending on the intensity of the light source to irradiate, the decomposition of the resin molecules proceeds from the thin part of the cell film, so the cell film close to the skeleton is slightly thicker, so it does not decompose and becomes a fin shape. Remains. In the case of ultrasonic waves, the cell membrane vibrates, and the nodes of the vibration are fatigue-deteriorated and rupture. The node portion is not at the root of the skeleton, but at a slightly distant position, and the space between the node and the skeleton remains in a fin shape. Its size is about 1% to 25% of the cell radius of the urethane foam. By adjusting the processing conditions of ultraviolet rays or ultrasonic waves, when operated from one side, the probability of the cell membrane remaining on the opposite side increases, and when operated from both sides, the probability of the cell membrane remaining in the center increases. Increase. In the case of ultraviolet rays, the cell film is destroyed closer to the irradiation side, and the number of the destroyed cell films decreases as the distance increases, so that the number of remaining cell films has a tilt structure in the thickness direction.
In the case of ultrasonic waves, the cell film on the surface is destroyed, and the film is removed, thereby following the process of destroying the next cell film. Go. Accordingly, this operation also has a structure in which the number of ruptured films decreases sequentially in the depth direction, and the number of remaining cell films has an inclined structure in the thickness direction.

When ultraviolet rays are used, an ultraviolet lamp used for curing the resin with ultraviolet rays may be used as a light source. Table 1 shows an example. In particular, the one in which the wavelength region of the maximum energy peak at the time of light emission is in the near ultraviolet region is more efficient. In addition to these ultraviolet lamps, excimer lasers also emit ultraviolet light, but since they have different effects on urethane rupture, they are not included here.

The amount of ultraviolet light also affects the type of urethane resin. However, if the amount is too large, not only the cell film is completely destroyed and not only a slanted structure but also a skeleton but also a skeleton can be destroyed. If the amount is too small, the membrane cannot be broken. In the experimental example, the thickness is 3mm
When the ester-based polyurethane foam is ruptured using a high-pressure mercury lamp, the integrated light amount is 0.6 J / cm.
Good results were shown in the range of ^{2 to} 18 J / cm ² .

[0022]

[Table 1]

Irradiation of the ultraviolet ray is a variable factor depending on the light source, the distance between the light source and the object to be irradiated, the irradiation time, the use of reflection on the back side, and the characteristics of the urethane resin used therefor. As a guide, a high-pressure mercury lamp for ultraviolet curing is used, and the irradiation is preferably performed at a distance of 1 to 30 cm, preferably 2 to 30 cm.
It is preferable to carry out in about 5 seconds to about 5 minutes. Of course, when irradiating a continuous sheet, the total irradiation time may be controlled according to the feed speed. In addition, when a large amount of the cell film is left in the central part, the irradiation can be achieved by shortening the irradiation time by bringing the light source closer and irradiating the light from the front and rear surfaces.

It is also preferable to intentionally reduce the integrated light amount of ultraviolet rays and remove the remaining cell film by physical shock, vibration or swelling from the viewpoint of avoiding deterioration of the skeleton. The physical impact and vibration by this means include ultrasonic waves, microwaves, air vibrations, pressurization, and the like, and ultrasonic waves or air blows are preferably used efficiently. As for the swelling, any liquid may be used so long as it swells the urethane resin, but it is preferable to select from water, an organic solvent, and a mixture thereof. It is preferable as a means for improving familiarity or coating by dissolving the resin therein. Further, in the case where the processing of the paste or the like is provided in the post-process, the post-process can be used as a batch process with the solvent in the paste.

In the case of rupture using ultrasonic waves, it is convenient to use a transducer used for an ultrasonic cleaner or an ultrasonic homogenizer as an oscillation source. 10-1
50 kHz is often used. The transducer is immersed in a liquid, and the upper or lower part of the transducer is passed through a sheet-like urethane foam to break the membrane. The time required for rupture is
For example, output 300W, effective area of oscillation terminal 5.2cm
^{With 2} transducers, a sheet of 3 mm thickness is sufficient for a few seconds to a few minutes. Also in this case, in the continuous processing, it is possible to cope with the passing speed by increasing the output of the transducer, increasing the area of the oscillation terminal, or arranging a plurality of transducers. Further, the selection of the liquid to be immersed can also change the efficiency, and the processing in the next step can be combined. For example, if hot water is used instead of water, or if a phenol resin aqueous solution is used, membrane rupture can be performed more efficiently. In the case of a liquid that swells the urethane resin such as a phenol resin aqueous solution, the liquid can be returned to the original size by removing the liquid by air blow or the like after the treatment and drying. Due to the short time, the swelling effect cannot be expected very much. The urethane foam that has been ruptured here does not generate low-molecular substances, decomposition products, radicals, etc., which decompose urethane molecules due to ultraviolet treatment. Is a clean, ruptured urethane foam.

1% of the cell radius is added to the skeleton thus obtained.
The ruptured urethane foam having a fin-shaped portion having an average length of from 25 to 25% and having an inclined structure has a larger surface area than the framework portion of the urethane foam obtained by the conventional explosion treatment. In particular, when the untreated cell film remains, the front and back of the cell film are counted as the surface area, so that the surface area is effectively increased more than the fin portion. When the remaining cell film remains as an inclined structure like the urethane foam used in the present invention, the surface area greatly differs in the thickness direction.

FIG. 1 shows an enlarged view of the skeleton of the urethane foam used in the present invention.
Since almost all of them correspond to the boundary of three cells as in the cross section, they have a shape close to a triangle, and the leading end thereof remains as the fin 2 with the rest of the cell film. In contrast, FIG. 2 shows a skeleton of a conventional broken-walled urethane foam. Although the skeleton shows a shape close to a triangle like FIG. 1,
There is no fin in the skeleton 1 only.

As described above, the length of the fin has a width depending on the degree of progress of decomposition by irradiation of ultraviolet rays and the position of a node of ultrasonic vibration. Within the scope of the present invention, its length is defined as follows. Urethane foam is an accumulation of resin foam, and if one foam is taken, a cell as shown in FIG. 3 is obtained. There is a skeleton 1 at the boundary with the surrounding bubbles, and there is a cell membrane 3 between the skeletons. The cell diameter D varies depending on the foaming conditions of the urethane foam used. The width of the cell membrane is smaller than the diameter D of the cell, and in such a foam, the width of the cell membrane is only about the cell radius D / 2. Although it is difficult to control the width of the cell membrane, the cell diameter can be controlled by the foaming conditions. The average length of the fin length of the urethane foam subjected to the membrane rupture treatment according to the present invention based on this scale is 1% to 25%. However, the probability of exceeding an average of 15% is low.

FIG. 4 shows two types of structural examples of urethane foam having fins having different cell membrane residual ratios as the material of the porous metal body having a structure inclined in the thickness direction of the present invention. FIG. 4A shows an example in which the surface area has an inclined structure in one direction, and FIG. 4B shows an example in which a central surface has a large surface area and the front and rear surfaces have a small surface area. A portion 4 where the cell membrane breakage rate is higher as the surface is closer to the surface to be treated by ultraviolet rays or ultrasonic waves, and a part 4 of the cell membrane that is not broken remains slightly;
It is divided into three regions: a portion 5 in which about 20 to 60% of the initial cell film remains, and a portion 6 in which 70% or more of the initial cell film remains, but the substance is continuously changing.

FIG. 5 is an enlarged view of the rupture state of the three regions shown in FIG. 5A corresponds to the portion 4 in FIG. 4, FIG. 5B also corresponds to the portion 5, and FIG. Although the skeleton 7 is flat in the drawing, it actually extends three-dimensionally. This skeleton has the cell film 9, and when the film is broken, a part of the cell film 9 remains and the fin portion 8 is formed.
Becomes The ruptured portion becomes a hole 10 and communicates with an adjacent cell film.

Using the urethane foam having the fins in the skeletal portion and having an inclined structure in the surface area, the metal adhesion treatment according to the conventional technique is applied to the ruptured urethane foam produced by the explosion treatment. A similar process can be performed to obtain a porous metal body. Although there are many combinations of the means as described above, the present invention is particularly different from film rupture processing by explosion processing in that it can be processed in the form of a sheet. That is, it is possible to form a process continuously with the post-process.

Next, a porous metal body is formed by the following steps. The ruptured urethane foam may be in the form of a sheet or a block, but in the case of a block, an instrument for grasping a part of the block is required. In the case of a sheet, once the end is introduced into the apparatus, the sheet can be continuously processed simply by connecting the sheets. All of the following steps can be handled in the same manner, but here, description will be made for each means.

(A) Means for conducting electroplating after conducting treatment As means for conducting treatment of the broken urethane foam, a method of attaching metal powder, carbon, graphite, or the like as a conductive material can be used. When attaching metal powder, if it does not affect metal plating in the subsequent process,
Any metal can be used, but it is wise to choose the same type as the metal to be plated. If there is a problem such as alloying with a metal in a later step, a material to be incinerated in the firing step such as carbon or graphite is selected. Depending on the use, alloy powder may be used intentionally. Further, a mixture of metal and carbon is also possible.

In order to apply the conductive material to the urethane foam, a small amount of resin may be mixed and formed into a paste with a solvent or the like. After the paste is applied, excess paste is removed by a roll or the like, and the paste is dried.
In the foamed urethane foam of the present invention, the paste is applied to both the fin portion and the unbroken cell film, so that the plating area is increased. The skeleton of urethane foam has a resin at the center and a small amount of resin at the fins, but the conductive portion is a portion to which the paste on the surface is applied, so that the plating amount also increases per unit volume.

After the plating, the resin is washed with water and dried, and then the resin inside is decomposed and removed in an incinerator. At this time, if metal powder is used as the conductive paste material, alloying with the plating metal is expected. If it is carbon or the same metal, it will be a single metal porous body. Thereafter, the metal oxide is reduced in a reducing atmosphere to complete the porous metal body. The metal adheres to both the fin portion and the unbroken cell membrane, which increases the surface area of the porous metal body. In particular, the metal adhering to the remaining cell film portion increases the effect of increasing the surface area.

(B) Means for Electroless Plating and Further Electroplating In the electroless plating, urethane foam which has been subjected to film breakage can be directly treated. By forming a metal film having a thickness of about 0.1 to several μm on the urethane skeleton by a known Kanigen plating method, conductivity can be imparted. This enables electroplating, and the subsequent steps are the same as the steps after (a) electroplating.

(C) Means for further electroplating after physical vapor deposition Physical vapor deposition includes sputtering, ion plating, vacuum vapor deposition and the like. Since each of these operations is performed under reduced pressure or vacuum, it is difficult to connect to the subsequent steps. For example, in the sputtering method, 1 to which Ar gas is introduced.
By scattering metal particles from a metal target by plasma discharge under a reduced pressure of about 0.1 Pa, a metal film can be formed on urethane. At this time, preferably, the adhesion of the metal film can be improved by heating the urethane to about 200 ° C. The metal film imparts conductivity to the urethane, and the subsequent steps are the same as the steps after the electroplating of (a).

(D) Means of sintering after applying a paste of paint containing metal powder Among the conductive treatment pastes used in means (a), those using metal powder are similar. However, unlike a mere conductive treatment, this method forms a thick metal layer only in this step. For this purpose, the paste needs to have a high concentration of metal powder and a thick coating. For this reason, if the fin portion of the foamed urethane foam is too long, it will be embedded in the skeletal portion due to the application of the paste. Those not present are preferred. Preferably, it is better to keep the cell radius to 10% or less. When the unbroken cell film is not broken by the application of the paste, the paste is applied to the entire surface of the film without being embedded in the skeletal portion.

After the paste is applied, excess paste is removed by a roll or the like and dried, and the resin is decomposed and removed in a sintering furnace. At this time, since there is sintering of the metal, a reducing atmosphere is preferably used. Since the paste is also applied to the fin portion, the porous metal body is formed with the fin portion remaining.
In this state, the sintering force between the metal powders may be insufficient in this state. Therefore, a means for obtaining a predetermined amount of metal by further performing electroplating using the porous metal as a cathode is also available. is there. Depending on the intended use, if the metal formed on the base is unsuitable for the use environment or there is a risk of deterioration, or if it adversely affects the use, there is also a means of electroplating another metal that can cover it. is there.

(E) Means for applying a paste of a paint containing a metal compound and then reducing and sintering It is almost the same as the means of (d) above, except that the metal part contained in the paste used is a metal compound. In addition to metal oxides, metal carbides, metal sulfides, metal chlorides, metal phosphides, etc., they may be acid compounds or complex salts, but by-products that fuse with the metal when the resin is decomposed and incinerated in a later step. Are not preferred. A paste using these powders is applied to urethane foam. After that, a porous metal body is obtained in the same manner as in the method used in the means (d). In this case, similarly to the means (d), electroplating using the obtained porous metal as a cathode is also preferable as a means for improving the strength. Depending on the intended use, if the metal formed on the base is unsuitable for the use environment or there is a risk of deterioration, or if it adversely affects the use, there is also a means of electroplating another metal that can cover it. is there.

The surface area of the porous metal body thus formed is larger than that of the porous metal body produced using the ruptured urethane foam obtained by the explosion method, due to the fin portion and the remaining cell membrane portion. As in the present invention, when using a material in which the ratio of the remaining cell film changes in the thickness direction, the surface area of the metal changes in the thickness direction of the completed porous metal body,
The amount of adhered metal also has an inclined structure, and the porosity has an inclined structure, though slightly. The effect of the increase in the surface area appears in the current collecting effect of a battery manufactured using the porous metal body as a substrate.

Particularly, when used as a battery substrate, FIG.
When the active material is packed into the porous metal body formed as shown in (a) from the portion 4 having less residual cell film, the active material does not enter the portion 6 having more residual cell film. In the part 6, the metal cell is broken and becomes a metal plate. Therefore, this part 6 becomes effective as a current collector. FIG.
In the case of a metal porous body in which the cell film is concentrated at the center as in (b), the active material is packed from both sides and compressed,
The central part becomes the current collector.

[0043]

(Example 1) A film having a thickness of 3 mm was cut out from the broken urethane foam by using an ester-based urethane foam having 42 cells per inch and explosion treatment was performed. ). A sheet having a thickness of 3 mm was cut out from the same urethane foam block before the film rupture, and ultraviolet light was applied to the sheet to perform a film rupture treatment. The processing device used was a UV curing device manufactured by Eye Graphics Co., and the light source used was a high-pressure mercury lamp H03-L31 (3 kW) 1.
20 W / cm. The irradiation distance was set to 50 mm, the back side of the irradiation object was released so that ultraviolet rays were not reflected, irradiation was performed for the time shown in Table 2, and then the irradiation object was turned over and irradiation was performed for the same time. However, samples D and E were irradiated only on the front side. The average length of the fins of the broken urethane foam is changing in the thickness direction, but the average of the whole is
The results as shown in Table 2 were obtained in terms of the ratio to the cell radius. In Table 2, the samples other than the comparative sample (Z) are the working samples of the present invention, but the sample F was out of the range of the working examples because the average length of the fins with respect to the cell radius was too long.

[0044]

[Table 2]

(Example 2) A porous metal body was produced by the following method using the urethane foam having the ruptured membrane produced in Example 1. Production method a: A carbon paste was applied to the skeleton of the broken urethane foam using a squeezing roll, and dried to impart conductivity. This sample was used as a cathode, immersed in a watt bath, and subjected to electric Ni plating. Thereafter, a heat treatment is performed at 1000 ° C. for 10 minutes in a furnace in a reducing atmosphere to obtain Ni
Was obtained.

Production method b: Electroless Ni plating was applied to the skeleton of the foamed urethane foam to impart conductivity. After that, it is immersed in a watt bath, plated with Ni, and
After giving i amount, it was kept at 1000 ° C. in a furnace in a reducing atmosphere and heat-treated for 10 minutes to obtain a Ni metal porous body.

Production method c: Nitrogen was vacuum-deposited on the urethane foam that had been ruptured to a size that would fit in a container. Once removed, it was turned over and the same operation was repeated again to apply a Ni film to the entire skeleton. This was immersed in a watt bath, and a predetermined amount of Ni was plated by electric Ni plating. Thereafter, heat treatment was performed at 1000 ° C. for 10 minutes in a reducing atmosphere to obtain a Ni metal porous body.

Production method d: Ni powder 50 wt%, liquid phenol resin 10 wt%, carboxymethyl cellulose 2 w
The mixture was mixed at a ratio of t% and water of 38 wt% and mixed for 10 minutes using a sand mill to prepare a slurry liquid. The foamed urethane foam is immersed in the slurry liquid, excess adhesion is removed by a squeeze roll, and the urethane foam is removed in a thermostat kept at 120 ° C.
And dried. Then, a reducing atmosphere of 1050
A heat treatment was performed for 10 minutes in a furnace maintained at a temperature of 10 ° C., and at the same time, the metal powder was sintered to obtain a porous Ni metal body.

Manufacturing method e: Fe ₂ O ₃ powder 50 wt%, liquid phenol resin 10 wt%, carboxymethyl cellulose 2 wt%, water 38 wt% were blended, and mixed for 10 minutes using a sand mill to prepare a slurry liquid. The foamed urethane foam was immersed in the slurry liquid, excess adhesion was removed by a squeeze roll, and the film was dried in a thermostat kept at 120 ° C. for 5 minutes. Then, 1100 ° C in a reducing atmosphere
Was performed in a furnace maintained at a temperature of 10 ° C., and simultaneously, a porous Fe metal body was obtained by reduction sintering. The Fe porous body was immersed in a Watt bath and subjected to an electric Ni plating treatment to form a Ni layer on the surface, thereby obtaining a Fe / Ni two-layer porous metal body.

Table 3 shows the results obtained by measuring the basic characteristics of some samples by the above-mentioned production method and the selection of the urethane foam having the ruptured membrane obtained in Example 1. From this result, it can be seen that the characteristics are comparable to the basic characteristics of a porous metal body using urethane foam formed by a commonly used explosion method. Here, the names of the samples are in the order of urethane foam sample type-means for metallization.

[0051]

[Table 3]

(Example 3) The urethane foam produced in Example 1 was replaced with a porous metal body produced by the production method in Example 2.
Samples whose basic characteristics were evaluated in Table 3 were selected to manufacture nickel electrodes for batteries. A paste mainly composed of nickel hydroxide was used as an active material, filled in a porous metal body, the surface was smoothed, and then dried at 120 ° C. for 1 hour. This sheet is 10
A nickel electrode was formed by applying a pressure of 00 kg / cm ² and cutting to a length of 280 mm, a width of 180 mm, and a thickness of 0.6 mm.

A rectangular sealed nickel-metal hydride battery was constructed using the five nickel electrodes, five known MmNi (Misch metal nickel) -based hydrogen storage alloy electrodes as counter electrodes, and a hydrophilically treated polypropylene nonwoven fabric separator. As the electrolytic solution, 20 g / l lithium hydroxide is dissolved in an aqueous caustic potassium solution having a specific gravity of 1.3.

After the completed battery was once charged, the discharge voltage (V) and the capacity (Ah) at a discharge current of 10 A and 150 A were examined. In addition, as a life test, the capacity retention rate (%) after 500 cycles at 10 A discharge was evaluated. Table 4 shows the results. Comparative samples Za and Z-
In e, the active material can be filled in a large amount, but since the distance between the active material and the metal skeleton increases, the current collection efficiency decreases.
Therefore, when discharging a high current at once, the discharge capacity is 93 to 9
This is a phenomenon of decreasing to 4 Ah. Repeated discharging and discharging also tends to lower the capacity retention rate. Sample Fa
Since there are many fins remaining on the whole,
When the active material is filled, the resistance is large and the filling amount is small. Therefore, the charging capacity is small, and as a result, the discharging capacity is small, which is not suitable. From this determination, the porous metal body according to the present invention is effective as a battery electrode plate which is much more improved than conventional products, and particularly when a high current is discharged at one time and when the charge / discharge operation is repeated, the life is extended. ,
It is effective.

[0055]

[Table 4]

[0056]

As described above, the porous metal body according to the present invention is different from a uniform porous metal body in that a special performance is obtained depending on the method of use. As described above, the effect of increasing the surface area by the metal cell film is a factor of the effect. In addition, the central portion or the portion with a high metal density concentrated on one side becomes a metal current collector during the production of the battery substrate, from which the metal net gradually spreads, and efficiently collects the power generated by the active material. Since it has a structure that can be used, it has the effect of maintaining the capacity during repetition of charge and discharge, which is the use characteristic of the secondary battery, and has a convenient structure even when taking out a large current at a stretch, Especially effective.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a skeleton having a fin portion of urethane foam as a material of the present invention.

FIG. 2 is an explanatory diagram of a skeleton of urethane foam, which is a material of a conventional porous metal body.

FIG. 3 is an explanatory diagram of a cell radius serving as a reference for the length of a fin portion of the present invention.

FIG. 4 is an explanatory view of urethane foam having an inclined structure, which is a material of the present invention. (A) This is an example in which a tilt structure is provided in one direction. (B) This is an example in which the central portion has a structure with a large surface area.

FIG. 5 is a partially enlarged view of urethane foam having an inclined structure, which is a material of the present invention. (A) A part where a cell film slightly remains. (B) A portion where about 20 to 60% of the initial cell film remains. (C) A portion where 70% or more of the initial cell film remains.

[Explanation of symbols]

 1. 1. Skeleton Fin part 3. 3. Cell membrane 4. Part where cell membrane is slightly left 5. A portion where about 20 to 60% of the initial cell film remains. 6. A portion where the cell film remains at 70% or more of the initial state. Skeleton 8. Fin part 9. Cell membrane 10. Vacancy

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keizo Harada 1-1-1, Koyo Kita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Masasaku Yamanaka 1-1, Koyo-Kita, Itami-shi, Hyogo No. 1 Sumitomo Electric Industries, Ltd. Itami Works

Claims (7)

[Claims] 1. A metal porous body having a three-dimensional network structure in which a plurality of cells are combined, and a fin having an average length of 1% to 25% of a cell radius in a skeleton portion of the cell, and A porous metal body having an inclined structure, characterized in that a metal filling density changes in a thickness direction. 2. The metal porous body having an inclined structure according to claim 1, wherein the packing density of the metal continuously increases at the center of the thickness. 3. The porous metal body having an inclined structure according to claim 1, wherein the packing density of the metal changes in one direction from a surface layer portion to a back surface portion. 4. The porous metal body having an inclined structure according to claim 1, wherein the metal has two layers of a metal covering a surface and an internal metal. 5. Using urethane foam as a substrate, a) conducting a conductive treatment and then electroplating; b) electroless plating and electroplating; and c) performing physical vapor deposition plating. Means for electroplating, d) means for applying and sintering a paint paste containing a metal powder, e) means for applying and applying reduction paste after applying a paint paste containing a metal compound, f) physical or chemical After coating a metal or a metal compound by a vapor phase deposition method, sintering or reduction sintering is performed. A method for producing a porous metal body having a tilted structure, which is performed by an ultraviolet treatment or an ultrasonic treatment. 6. The metal porous body having an inclined structure according to claim 3, wherein the film-breaking treatment is an ultraviolet treatment, and thereafter, any one of physical shock, vibration, and swelling or a combination thereof is added. How to make the body. 7. A battery substrate, wherein the porous metal body having the inclined structure according to claim 1 is used for an electrode plate used for a battery.