JP2000268827A - Metal pseudo porous substance and its manufacture, electrode plate for battery using the same and manufacture of plates, and battery using electrode plates - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide metal pseudo porous pieces causing no projections on the surface in the compression process in a method of filling an active material using an active material filling tool upon studding metal short fibers on a base board in an inclination in substantially one direction and to provide an electrode plate for battery not requiring the metal short fibers to be shorter than the active material to be applied for filling and not degrading the discharging characteristic at a large current. SOLUTION: An electrode plate for battery is formed with metal pseudo porous pieces structured so that metal short fibers 2 are studded on a base board 1 in inclination substantially parallel with one another at an angle θ with respect to the board 1. These metal pseudo porous pieces are manufactured by orienting metal short fibers 1 having magnetism by a magnetic field and studding them on base board applied with adhesive, removing the resin of a binding medium, baking, filling the active material in the direction in which the metal short fibers 2 are inclined, and subjecting the obtained object to a pressurizing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal pseudo-porous body used for an electrode plate for a battery and a method for producing the same.
The present invention relates to a battery electrode plate using the metal pseudo-porous body, a method for manufacturing the same, and a battery using the battery electrode plate.

[0002]

2. Description of the Related Art Conventionally, spongy 3 has been used as an electrode plate for a battery.
Metal foam porous bodies having a three-dimensional network structure are widely used.
Conventional metal foam porous body, after performing a process of forming a metal film by chemical plating on the resin foam and imparting conductivity,
Further, a metal layer is formed by electroplating. Thereafter, the metal foamed porous body is obtained by heating at a predetermined temperature for a predetermined time and performing sintering. However, since the metal foamed porous body is manufactured using plating equipment, the manufacturing cost is high. Also, in the battery electrode plate using the metal foamed porous body, the utilization of the filled active material is about 90%, and the substantial contact area cannot be increased, so that the discharge characteristics at a large current are not improved. Had the problem of.

Accordingly, as disclosed in Japanese Patent Application Laid-Open No. Hei 9-265991, the present inventor has proposed a method of forming a metal-containing fiber comprising a metal powder having magnetism and a resin as a binding medium on a metal substrate in a sword-like manner. A porous metal body formed by the above was invented. The porous metal body vertically orients short fibers made of a magnetic metal or alloy (hereinafter, all of these metal-containing fibers, metal fibers, and alloy fibers are referred to as short metal fibers) on a substrate by magnetic force. After arranging them, they are fixed to form metal short fibers on both sides of the metal substrate in the shape of a sword. Since the metal porous body has a high active material filling degree and a large contact area between the active material and the electrode substrate,
In particular, it has been useful as an electrode substrate for a secondary battery for an electric motor that may require a large current.

[0004]

When a battery electrode plate is formed using a porous metal body in which short metal fibers are vertically erected on a substrate as described above, the following problems occur. There was something. Hereinafter, problems of the related art will be described with reference to FIGS. 8A to 9B.
The first problem is separation of short metal fibers from the substrate, which occurs when the porous metal body is filled with the active material. As shown in FIG. 8A, in the active material filling step, the active material application section 30 is used.
Of the active material 31 is ejected from the injection port, and the active material 31 is discharged from the metal porous body 5.
No. 3 is filled. At this time, since the short metal fibers 51 stand perpendicularly to the substrate 52, the active material 31
The metal short fibers 51 move in the traveling direction of the nozzle 30 due to the viscosity of
A force 50 is exerted. Therefore, as shown in FIG. 8B, the short metal fibers 51a
Sometimes occurred.

[0005] The second problem is that the short metal fibers fall or break in the pressurizing step of compressing the porous metal body 53 filled with the active material. This pressurizing step is a step performed to increase the filling density of the filled active material, and as shown in FIG. 9A, a metal porous body 53 filled with an active material is sandwiched between rolls 40 from above and below. A compression method is used. On this occasion,
Among the short metal fibers 51 standing perpendicular to the substrate 52, the short metal fibers 5 inclined in the direction opposite to the compression direction are included.
1b. Then, as a result of the compression, as shown in FIG. 9B, short metal fibers 51c which fall in the direction opposite to the compression direction are generated. In some cases, as shown in FIG. 9C, the metal short fibers 51 that are broken in the middle of the length direction.
d occurs.

The above two phenomena cause the formation of protrusions on the surface of the porous metal body after compression in both cases.
Such projections, when assembled into a battery, cause the separator sandwiched between them to prevent short-circuiting between the electrode plates or cause a hole to be formed, thereby lowering the yield of the completed battery. As a solution to this problem, it is conceivable to shorten the length of the short metal fibers to be grown on the substrate. That is, if short metal fibers shorter than the thickness of the active material layer to be filled and applied on the porous metal body are established, the short metal fibers do not appear as protrusions on the surface of the completed electrode plate. However, this method has a problem that the contact area with the active material is reduced, and the discharge characteristics, particularly, the discharge characteristics at a large current are deteriorated. Since the large current characteristic of the secondary battery is the most noticeable characteristic in the field of electric vehicles and the like, which is expected to greatly expand in the future, a solution for preventing the deterioration of the large current characteristic has been desired.

According to the present invention, there is provided a method of filling an active material with an active material filler using a method in which short metal fibers are inclined in a substantially constant direction with respect to a substrate and filled with an active material filler. It is an object of the present invention to provide a metal pseudo-porous body that does not generate protrusions. Another object of the present invention is to provide a battery electrode plate which does not require the length of the short metal fiber to be shorter than the thickness of the active material layer to be filled and applied, and which does not deteriorate the discharge characteristics at a large current.

[0008]

In order to solve the above-mentioned problems, a metal pseudo-porous body of the present invention has a fiber axis of short metal fibers on a substrate which is substantially parallel to each other at a predetermined angle with respect to the substrate. It is characterized by being formed to be inclined and oriented.
According to the metal pseudo-porous body, the short metal fibers are prevented from being detached from the substrate due to the force applied to the short metal fibers when the active material is filled, and can be compressed without causing any protrusion on the surface in the compression step. Therefore, if a battery electrode plate is formed using this metal pseudo-porous body, a battery electrode plate can be formed without damaging or puncturing the separator. Further, since it is not necessary to form the short metal fibers even shorter, the discharge characteristics are not deteriorated.

Further, in the method for producing a pseudo-porous metal material according to the present invention, a step of forming an adhesive layer on a substrate surface and a step of forming a short metal fiber having magnetism while applying a magnetic field above the substrate on which the adhesive layer is formed are performed. Dropping the metal short fibers on the substrate and tilting the substrate substantially parallel to each other to form a forest, and applying a magnetic field to the substrate where the metal short fibers are inclined and growing. Curing the adhesive layer and fixing the short metal fibers to the substrate substantially parallel to each other, and sintering the substrate with the short metal fibers. I do. According to the method for manufacturing a pseudo-porous metal body, short metal fibers having magnetism can be formed on a substrate by a magnetic field so as to be inclined substantially in parallel to each other in a predetermined direction.

The battery electrode plate of the present invention is a battery electrode plate in which an active material is formed by filling and coating the pseudo-porous metal of the present invention with an active material. Is formed thinner than the height of the short metal fibers of the pseudo metal porous body,
The short metal fibers protruding from the active material layer are bent in a direction inclined to have a predetermined thickness. According to this battery electrode plate, it is possible to provide an electrode plate that does not damage the separator since projections of short metal fibers do not occur on the surface, and it is possible to increase the contact area between the short metal fibers and the active material. Therefore, it is possible to provide a battery electrode plate having excellent discharge characteristics at a large current.

In the method for producing a battery electrode plate according to the present invention, the active material is applied along the inclined direction of the obliquely oriented short metal fibers of the pseudo metal porous body of the present invention.
A step of forming an active material layer having a thickness lower than the height of the short metal fibers, and compressing the short metal fibers in an inclined direction to bend the protruding short metal fibers onto the active material layer to have a predetermined thickness. Forming an electrode plate. According to this manufacturing method, the battery electrode plate of the present invention can be easily manufactured.

Further, the battery of the present invention is characterized in that the battery electrode plate of the present invention is used at least as a positive electrode. According to this battery, since there is no protrusion on the electrode plate, it is possible to manufacture a battery with a good yield by preventing the occurrence of defects such as short-circuiting of the electrode plate, and to increase the contact area between the short metal fiber and the active material. Therefore, discharge characteristics at a large current can be improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below. A pseudo metal porous body and a method for manufacturing the same according to the present invention will be described as a first embodiment with reference to the drawings. A method for manufacturing a battery electrode plate according to the present invention will be described as Example 2 and a preferred example of a battery will be described as Example 3 with reference to the drawings.

<< Embodiment 1 >> Hereinafter, Embodiment 1 according to the present invention will be described.
The pseudo metal porous body and the method of manufacturing the same will be described with reference to FIGS. FIG. 1 is a side view showing a schematic configuration of the pseudo metal porous body of Example 1. FIG. 2 is a process diagram showing a process for producing short metal fibers used in Example 1. FIG. 3A is a longitudinal sectional view illustrating an example of the short metal fiber used in the first embodiment. FIG. 3B is a cross-sectional view of the short metal fiber of FIG. FIG. 4 is a diagram illustrating a process for manufacturing the pseudo-porous metal body of Example 1. In FIG. 1, a substrate 1 is formed of a conductive metal because it is used as an electrode plate for a battery. In nickel-metal hydride batteries and lithium-ion batteries, which are becoming mainstays as recent secondary batteries, the substrate 1 is mainly formed of a nickel plate. As the shape of the substrate 1, besides a plate shape, a cloth shape obtained by weaving fibrous metal or a nonwoven fabric obtained by collecting and compressing fibrous metal can be used. Further, if necessary, the surface of the substrate 1 is subjected to a process such as plating, or a process such as a perforation process for providing a large number of small through holes for increasing the contact area with the active material and increasing the adhesive force. You.

The short metal fibers 2 have conductivity and are planted on the substrate 1 in order to increase the contact area with the active material. The same material as that of the substrate 1 is preferably used. The short metal fibers have a length of 0.2 mm to several mm, a thickness of tens to several hundreds of μm. If too long, it will be difficult to fill the active material, if too thick,
The amount of active material per unit volume is reduced. The planting density of short metal fibers is 1200 to 1 per cm ^2.
About 800 are preferable. The substrate 1 and the short metal fibers 2 are fixed by firing so as to be integrated. The inclination angle θ of the short metal fiber 2 with respect to the substrate 1 is about 30 degrees to 7 degrees.
An angle range of 0 degrees is desirable, and good results have been obtained, especially at about 50 degrees. If the inclination angle is too large, the same problem as in the case of standing vertically as described in the conventional example occurs. On the other hand, if the inclination angle is too small, it falls down at the time of filling the active material, and the inclination angle approaches 0 degree, so that the effect of increasing the contact area with the active material cannot be exhibited.

A method for producing the short metal fibers 2 and a method for arranging the short metal fibers 2 on the substrate 1 are described in JP-A-10-129.
No. 235 and JP-A-10-94128 are used. Hereinafter, each of the specific manufacturing methods will be described, including references from the above documents. In the following description, both the fibers containing the resin as the binding medium and the fibers subjected to the treatment for removing the binding medium (hereinafter referred to as de-solvent treatment) and the calcination treatment are referred to as metal short fibers. Called.

[Explanation of Method for Producing Short Metal Fiber 2] The short metal fiber 2 used for the pseudo-porous metal of the present invention is oriented by using a magnetic field in the step of arranging the substrate to form an electrode plate for a battery. Must have magnetism. In a lithium-ion battery, a nickel-metal hydride battery, and the like, which are attracting attention as a secondary battery in the future, nickel is mainly used as an electrode plate. Nickel is a suitable material for the battery electrode plate material as the material of the short metal fiber 2 used in the present invention, which is required to have magnetism as well as electrical characteristics such as ionization tendency. By processing this nickel into a fibrous form as a metal, the short metal fibers 2 used in the present invention can be obtained. Specifically, there is a method of drawing molten nickel into a thread through a spinning nozzle, or shaving bulk nickel to obtain short fiber waste.

However, these methods are generally not easy and cause a high cost. In addition, since they are made of short fibers of pure metal, the weight becomes heavy, and the weight per unit area of the electrode plate (per unit area) Weight). Therefore, in the first embodiment, the kneaded nickel powder and the resin as the binding medium, which are drawn into a thread shape by the spinning method, are cut and used as the lighter metal short fibers 2 at lower cost.
As the metal nickel powder used in the spinning method, a powder having a particle size of about submicron to several hundred μm is used, and preferably several μm to several tens μm is suitable. This is because the short metal fibers 2 to be formed have a thickness of several hundred μm. In other words, if a metal powder larger than this range is used, spinning into a thread shape becomes impossible, and if a metal powder smaller than this range is used, the surface area of the metal powder becomes too large and kneading with the resin becomes difficult. is there. The shape of the metal powder is not particularly limited, such as a sphere, a square, a needle, and a plate. Further, several types of shapes may be mixed and used. Further, other non-magnetic particles may be included as long as nickel powder is contained as a main component.

As the resin serving as a binding medium to be kneaded with the nickel powder, an aqueous or organic solvent-based resin is preferably used. Specifically, polystyrene, polypropylene, polyethylene, polymethyl methacrylate, polyvinyl alcohol, polyvinyl butyral, polyacrylonitrile, polyethylene glycol, polylactic acid, a copolymer of ethylene and vinyl alcohol, a styrene acrylic copolymer, various celluloses Plastic,
Various nylons, polyurethanes, polyester thermoplastic elastomers, thermoplastic polyimides and the like can be mentioned. Depending on the required performance, the resin is selected from various resins including the above-mentioned resins. Among these, impurities are left in the desolvation step of removing the binding medium by thermal decomposition and the firing step of the short metal fiber and the substrate. A resin that does not exist is selected. That is, it is desirable to use an aliphatic hydrocarbon polymer containing oxygen that is easily decomposed by heating and is a resin that does not contain metal salts, cyclic bonds, and the like, which are left over by thermal decomposition. The binding medium does not need to be one kind of resin, and two or more kinds of resins can be mixed and used. In addition, a plasticizer, a dispersant, or the like can be used as the binding medium in addition to the above resin. Specific examples include butylbenzyl phthalate (DBP) and octylbenzyl phthalate (DOP).

The mixing ratio of the metal powder and the resin is as follows: metal powder (including magnetic and non-magnetic): resin is 90:10 to 60:40.
Can be used in a range up to. Desirably, the ratio of metal powder to resin is in the range of 85:15 to 70:30. If the content of the metal powder is larger than this range, the kneaded material cannot be formed into pellets, and spinning becomes difficult. On the other hand, if the content of the metal powder is less than the above range, there is a problem in the degree of bonding of the metal powder after sintering.

Next, the process for producing short metal fibers is shown in FIG.
This will be described with reference to FIG. As shown in FIG. 2, in the kneading step 6, a metal powder as a main material of the short metal fibers and a resin as a binding medium are sufficiently kneaded with a ball mill or the like to obtain a clay-like kneaded material. Known kneading machines such as a three-roll mill, a kneader, and an extruder can be used for the kneading in addition to the ball mill. In the pellet forming step 7, the clay-like kneaded material is formed into a pellet by an extruder. In the heating and melting step 8, the kneaded material formed into a pellet is heated to a melting temperature to be in a liquid state. In the spinning step 9, the kneaded material in a liquid state is pulled down through a spinning nozzle and processed into a fibrous shape.

At this time, as shown in FIG. 3, using a pellet having a high metal content, fibers having a high metal powder content are arranged on the core portion 4 and a sheath portion 5 on the outer periphery thereof for supplementing the strength. Composite spinning in which a resin is disposed on the substrate. The cross-sectional shape of the spinning nozzle may be various shapes such as a triangle, a square, a polygon having a larger number, a circle, an ellipse, and a star, and is not particularly limited. In the cutting step 10, the metal-containing fibers prepared in the spinning step 9 are cut to a required length to obtain the short metal fibers 2 used in Example 1.

[Explanation of a method of manufacturing a pseudo metal porous body in which short metal fibers 2 are erected substantially parallel to each other with respect to a substrate] A method of manufacturing a pseudo metal porous body of Example 1 will be described below. This will be described with reference to FIG. As shown in FIG. 4, the method for manufacturing a metal pseudo-porous body of Example 1 basically has the following four steps. (1) Adhesive layer forming step (2) Orientation (forest) step (3) Curing step (4) Firing step FIG. 4 shows a manufacturing method for continuously producing a sword-like metal pseudo-porous body, and a substrate. 1 is assumed to be transported from left to right in the figure by transport means (not shown).

In the adhesive layer forming step, the adhesive layer 14 is formed on the substrate 1 while spraying the adhesive 13 by the spray nozzle 12. As the adhesive 13, a mixture of resin and metal powder is used. The resin that can be used as the adhesive 13 is the same as the material of the binding medium used for manufacturing the short metal fibers 2 described above. However, it is desirable that the material be removed in the deoxidizing step or the firing step, and therefore, a material that does not leave a residue by burning at as high a temperature as possible is preferable. Specifically, as a resin used for the adhesive 13, a polyvinyl acetate resin, an acrylic resin, a butyral resin, or the like is used. Solvents for dissolving these resins include pure water and organic solvents other than hydrocarbon solvents such as butanol, methylcellosolve, cyclohexanone, methyl acetate, and tetrahydrophthalane for polyvinyl acetate resins. Organic solvents such as ketones such as methyl ethyl ketone and isophorone, ethers such as tetrahydrofuran and ethylene glycol monoethyl ester, and other organic solvents such as alcohol hydrocarbons can be used alone or in combination for the acrylic resin and butyral resin. The ratio between the resin and the solvent can be determined according to the viscosity, and can be determined in consideration of the drying speed and the like.

Considering that the metal powder is fired later, it is preferable to use a metal powder using the same main element as the main element of the short metal fiber 2 to be used. Here, the adhesive 13
The resin inside is necessary to fix the metal powder in the adhesive 13 and the short metal fibers 2 to be established, and the metal powder is bonded to the metal short fibers 2 and the substrate 1 to facilitate firing. Mixed in agent 13. Although the thickness of the adhesive layer 14 is not particularly limited, the adhesive layer 14 needs to have such a thickness as to achieve the function of bonding the short metal fibers 2 and the substrate 1 to be forested by firing. If the thickness is too large, there is also a problem that the weight per unit area of the battery electrode plate becomes heavy, and a thickness of 0.1 mm to several mm is suitable. Here, the method of forming the adhesive layer uses a spray nozzle. However, a coating method, a dipping method of forming an adhesive layer by immersing a substrate in an adhesive, or an adhesive layer formed on another plane in advance is used. Then, a method of transferring the same can be used. Since the purpose of this step is to form an adhesive layer on the substrate 1, it goes without saying that the present invention is not limited to these methods.

Next, the forestation process will be described. In this forestation step, while applying a magnetic field 16 by the electromagnet 15, the basket 18 containing the short metal fibers 2 having magnetism is shaken, and the short metal fibers 2 are dropped in a discrete state. Then, the short metal fibers 2 rotate in the air so as to be in the direction of the magnetic field 16, and land on the adhesive layer 14 on the substrate 1 in the direction of the magnetic field 16. Thereby, a stand-up state in which the short metal fibers 2 are inclined substantially parallel to each other at a predetermined angle with respect to the substrate 1 can be created.

The electromagnets 15 are arranged above and below the substrate 1, and a current flows so that the upper and lower electromagnets 15 generate a magnetic field 16 in the same direction. In the first embodiment, the electromagnet 15 is
Although one is used, either one of the upper side and the lower side of the substrate 1 can be used. Regarding generation of the magnetic field 16, either an electromagnet or a permanent magnet may be used, and the electromagnet and the permanent magnet may be used in combination. However, in the case of the present invention, it is preferable to use the electromagnet 15 that can control the magnetic field 16 in order to make the short metal fibers 2 stand substantially parallel to each other with respect to the substrate 1. further,
The magnetic field 16 may be a DC magnetic field or an AC magnetic field, and may be used in combination or in combination. At this time, the electromagnet 15
Is arranged so that the generated magnetic field 16 is inclined with respect to the substrate 1 on which it travels, so that the short metal fibers 2 fall with respect to the substrate 1 while being inclined substantially parallel to each other at a certain angle. A magnetic field 16 is applied.

The substrate 1 travels in a direction in which the metal short fibers 2 falling in an inclined state are caused to rise vertically to the substrate 1. Therefore, simply applying the magnetic field 16 obliquely to the substrate 1 is not enough to cause the short metal fibers 2 to stand on the substrate 1 at a predetermined angle substantially parallel to each other. It is necessary to adjust the inclination angle of the magnetic field 16 with respect to the substrate 1 and the strength of the magnetic field 16 in accordance with the traveling direction of the substrate 1, and the inclination angle and the intensity cannot be uniquely limited. As a method for dropping the short metal fibers 2, a method in which the short metal fibers 2 are put into the basket 18 and dropped while swinging the basket 18 has been described, but a method of dropping from a hopper having a slit or a so-called sieve is used. A method of dropping from such a mesh-like gap or a method of blowing and dropping with air can be applied. However, the present invention is not limited to these methods, as long as the metal short fibers 2 can be dropped in the magnetic field 16 in a state of being substantially parallel to each other and inclined at a certain angle with respect to the substrate.

Next, the curing step will be described. In this step, the metal short fibers 2 that have fallen and stood on the adhesive layer 14 are fixed by curing the adhesive layer 14. The short metal fibers 2 planted in the adhesive layer 14 in a state of being inclined substantially in parallel with the substrate 1 in the stand-up process stand by the action of the magnetic field 16, but lose their own weight when the action of the magnetic field 16 stops. And fall down. The purpose of this step is to cure and fix the adhesive layer 14 before it falls down. For this purpose, hot air is applied from a hot air nozzle 19 while the magnetic field 16 is applied so that the short metal fibers 2 do not fall down, and the adhesive layer 14 is cured. Therefore, the magnetic field 1 applied in this step
The direction of 6 acts in the same direction as the direction in which the short metal fibers 2 were established. The hot air is an air flow having a temperature of about 20 to 100 degrees, and a general hot air generator having a wind speed of several tens cm / sec to several tens m / sec can be used. However, the transfer speed of the substrate 1 and the magnetic field 1 acting on the curing process
6 or the length of the adhesive layer 14 to be used.
It is not possible to limit the temperature and the speed of the hot air in relation to the viscosity and the like of the hot air. Further, when hot air of an inert gas is preferable depending on the components of the adhesive layer, hot air of a nitrogen gas can be used.

The magnetic field 16 applied at this time is preferably a DC magnetic field rather than an AC magnetic field. This is because, in an alternating magnetic field, the polarity of the magnetic field is switched many times within a certain period of time, so that there is a possibility that the stapled metal short fibers 2 move. Therefore,
Not only electromagnets, but also magnetic fields from permanent magnets having a constant magnetic field polarity can be used. In FIG. 4, the application of the magnetic field applied in the forestation step and the curing step is performed by the same electromagnet 1.
Although it is shown that the operation is performed in step 5, separate magnets may be used.
For example, an electromagnet 15 can be used in the forestry process, and a permanent magnet can be used in the hardening process. Since the purpose of this step is to fix the short metal fibers 2 that have been established to the substrate 1 to the extent that they do not fall, the adhesive layer 14 does not need to be completely cured, and the short metal fibers 2 generate the magnetic field 16. What is necessary is just to harden to the extent that it does not fall without acting. In the first embodiment, the method of curing by applying hot air has been described. However, the curing may be performed by heating with a heater, or the resin may be cured at room temperature by using a resin having a high curing speed as an adhesive. In addition, when a special resin of an ultraviolet ray or electron beam curing type is used as the resin of the adhesive layer, a method of irradiating them and curing them can be used.

Next, the firing step will be described. This step includes a desolventization step of removing a resin component as a binding medium contained in the substrate 1 in which the short metal fibers 2 are established by the curing step by thermal decomposition, and a firing step of firing and solidifying the metal component. Contains. Accordingly, in the desolvation step, the atmosphere temperature is controlled from 300 degrees to 600 degrees by controlling the heater 21 of the firing furnace 20.
And the baking process is performed by changing the ambient temperature from 800 degrees to 120 degrees.
Perform at about 0 degrees. Depending on the material of the metal powder to be used, it is also possible to introduce hydrogen or a mixed gas of hydrogen into the firing furnace 20 through the atmospheric gas inlet 22 and discharge it through the exhaust port 23 to fire in a reducing atmosphere. Further, it can be performed in an inert gas atmosphere using nitrogen or the like.

It is preferable that the desolvation step and the calcination step be performed continuously, and after holding at a temperature of about 500 ° C. for a certain period of time,
It is desirable to perform the heating in the firing furnace 20 having a temperature distribution such that the temperature is increased from the temperature to 1200 degrees. Further, it is also possible to combine the atmosphere and the temperature rising pattern, for example, in a nitrogen atmosphere during the solvent removal step of maintaining the temperature at about 500 degrees, and in a reducing atmosphere in the high-temperature baking step. However, in the desolvation step and baking step, processing conditions such as temperature and holding time vary greatly depending on the baking furnace used and the size of the substrate to be processed, so it is necessary to confirm experimentally with reference to the above values Becomes

The above process is a method for producing a metal pseudo-porous body in which short metal fibers 2 are erected substantially parallel to each other at a predetermined angle on a single surface of a substrate 1 at a predetermined angle. After the completion of the above, by performing the same process on the back side of the substrate 1, it is also possible to form the short metal fibers 2 on both sides of the substrate 1 in a sword-shaped manner substantially parallel to each other at a predetermined angle. Specifically, (1) an adhesive layer forming step, (2) a forestry step,
(3) curing step, and turning the substrate 1 upside down, (4) adhesive layer forming step, (5) forestry step, (6) curing step, and (7) baking step
Thus, a pseudo metal porous body can be obtained in which the short metal fibers 2 are oriented in a sword mountain shape on both surfaces to form a forest.

Embodiment 2 Hereinafter, Embodiment 2 according to the present invention will be described.
The method of manufacturing the battery electrode plate will be described with reference to FIGS. FIG. 5 is a diagram illustrating an active material filling step in the method for manufacturing a battery electrode plate of Example 2. FIG.
FIG. 3 is a cross-sectional view illustrating a relationship between an active material filling amount and a height of short metal fibers in an active material filling step. FIG. 7 is a cross-sectional view illustrating a pressing step in the method for manufacturing a battery electrode plate of Example 2. An electrode plate for a battery can be manufactured through an active material filling step of applying and filling an active material to the pseudo metal porous body obtained in Example 1, and a pressurizing step of pressing the active material. As shown in FIG. 5, the active material filling step is a step of filling the pseudo metal porous body 32 with the active material 31. The active material 31 is supplied to the slit of the active material application unit 30 from the outside by a pump or the like (not shown), and the metal pseudo-porous body 32 in which the short metal fibers 2 are inclined substantially in parallel to the substrate 1 so as to stand. Filling is performed so that the metal short fibers 2 can be applied along the inclined direction. Specifically, the active material is filled in such a manner that the discharge direction of the active material from the active material application section 30 is parallel to the inclination direction of the short metal fibers. Here, the active material application section 30 is replaced with a metal pseudo porous body 32.
In the direction 33 in which the short metal fibers 2 are inclined (that is, the direction in which the direction from the base to the tip of the short metal fibers 2 is projected on the surface of the substrate 1), and the active material 31 is discharged from the slits. The metal pseudo porous body 32 is filled. By applying in such a direction, no extra external force is applied to the short metal fibers 2 and the short metal fibers 2 are prevented from detaching from the substrate 1.

In addition to the method of applying the active material described above, a method of applying the active material 31 to the surface of the metal pseudo-porous body 32 using a gravure plate is also possible. Also at this time, the coating is performed in the inclined direction of the short metal fibers 2 erected substantially parallel to each other on the surface of the substrate 1. As shown in FIG.
In the metal pseudo-porous body 32 filled with the active material as described above, the height A of the short metal fibers 2 from the substrate 1 is equal to the active material 3.
It is necessary to be larger than the coating thickness B of 1. As a result, the short metal fibers 2 are present over the entire area in the thickness direction of the applied active material 31, and the contact area of the short metal fibers 2 with the active material 31 can be sufficiently ensured, and the discharge characteristics at a large current can be improved. improves.

As shown in FIG. 7, the pressurizing step is performed using the active material 3
Pressure is applied to the metal pseudo-porous body 32 filled with 1 to increase the degree of filling of the active material 31. In this step, the metal pseudo-porous body 32 filled with the active material 31 is sandwiched between a pair of rolls 40, at least the surfaces of which are covered with a resin or the like, and passed while applying pressure. At this time, similarly to the above-described active material filling step, the roll 40 is rotated in the rotation direction 41 such that the short metal fibers 2 on the substrate 1 of the pseudo metal porous body 32 fall in the inclined direction. By doing so, there is no protrusion on the surface of the metal pseudo-porous body 32 after the pressing step, and when used as a battery electrode plate, it is possible to prevent the separator from being damaged.

Embodiment 3 Hereinafter, a battery according to Embodiment 3 using the metal pseudo-porous body according to the present invention as a battery electrode plate will be described. Nickel powder having an average particle size of 3 μm prepared by the carbonyl method was used as the metal powder, and the resin as the binding medium was butyral resin (BL made by Sekisui Chemical Co., Ltd .: BL
-1) was used. 75% by weight of metal powder and 20% by weight of butyral resin were mixed, and 5% by weight of DBP was added as a plasticizer, and the mixture was sufficiently kneaded to prepare a clay-like kneaded material. Then, the kneaded product was formed into a pellet by an extruder. The obtained pellets were heated to the melting temperature of butyral resin (about 200
° C), and the mixture was discharged from a spinning nozzle. The discharged metal fiber is not cooled and taken off as it is, but a draw-down magnification (winding magnification) 20
Wound in double. The winding speed at this time is about 70 m /
Minutes. The obtained metal long fibers were cut into a length of 2 mm to obtain short metal fibers. The average diameter of the short metal fibers was 150 μm.

Using this short metal fiber, a pseudo-porous metal body of Example 2 was prepared by the production method described in the above-mentioned Example 1. At this time, a nickel plate having a thickness of 0.6 mm was used for the substrate, and a perforation process was performed to reduce the weight per unit area. The size of the perforated hole is 1 mm in average diameter. An adhesive layer having a thickness of 0.7 mm was formed on the substrate by spraying as an adhesive layer with short metal fibers. The metal short fibers were dropped so that the average distance between them was about 0.9 mm. The traveling speed of the substrate was approximately 1 cm / sec, and the direction of the applied magnetic field was approximately 50 degrees with respect to the substrate. The strength of the applied magnetic field was about 500 Oe, and the inclination angle of the short metal fiber with respect to the substrate was about 50 degrees. Since the traveling speed of the substrate was very slow, the inclination angle of the direction of the applied magnetic field with respect to the substrate was almost the same as the angle formed between the completed substrate and the short metal fibers.

The substrate on which the short metal fibers thus formed were erected was dried and fixed while a magnetic field was applied. After that, the resin serving as a binding medium was removed by removing the solvent at 400 ° C. in a nitrogen atmosphere, and then subjected to a baking treatment at 1000 ° C. in a reducing atmosphere. The time of the deaeration treatment was about 30 minutes, and the holding time of the furnace at the temperature of 1000 ° C. for the baking treatment was 3 minutes.
After the firing treatment, natural cooling was performed in a reducing atmosphere.

Next, the active material filled in the pseudo metal porous body will be described. After mixing 92 parts of commercially available nickel hydroxide powder and 8 parts of cobalt oxide (CoO) powder, the mixture was mixed with a 2% by weight aqueous solution of carboxymethyl cellulose to prepare a paste of an active material. The paste was filled and coated on a pseudo-porous metal material and dried at 90 ° C. to obtain a battery electrode plate. The obtained battery electrode plate was subjected to a pressure treatment to 0.9 mm.
The thickness was adjusted. The electrode plate thus obtained was immersed in a 2% by weight aqueous solution of a fluororesin dispersion, and the width was 4 mm.
It was cut into 2 mm to obtain a positive electrode plate. On the other hand, as the negative electrode plate, a hydrogen storage alloy prepared in the following steps was used. As a material of the negative electrode, MmN5 which is one of MmNi ₅ series alloys is used.
Particle size 50 obtained by grinding i _3.55 Mn _0.4 Al _0.3 Co _0.75
An alloy powder having a diameter of not more than μm was immersed in a 30% KOH alkaline solution at 80 ° C. for 1 hour to remove an alkali-soluble component and to perform an activation treatment. The activated alloy powder was treated with 1.
Add 5% by weight CMC aqueous solution to make paste, thickness 1m
m, and pressed to form a negative electrode plate. Then, it is immersed in a 5% by weight aqueous solution of a fluororesin dispersion, cut into a width of 42 mm, and has a thickness of 0.5 mm.
mm to obtain a negative electrode plate.

The negative electrode plate and the positive electrode plate are wound with a polypropylene nonwoven fabric separator which has been subjected to a water immersion treatment, and
Stored in SC size battery case, KOH with specific gravity 1.30
An electrolytic solution in which 30 g / l of lithium hydroxide was dissolved was poured into the aqueous solution, and the case was sealed to obtain a nickel-metal hydride battery.

As described above, 50 batteries of Example 3 using the pseudo-porous metal body of the present invention were produced. In addition, in order to confirm the effect of the present invention, 50 batteries using a metal porous body of a conventional example in which short metal fibers to be grown on a substrate were vertically oriented on the substrate were similarly prepared. did. Table 1 shows the results of the short test performed on the battery of Example 3 and the battery of Comparative Example 1.

[0043]

[Table 1]

As shown in Table 1, the short-circuit failure of the battery using the conventional porous metal body of Comparative Example 1 was 6% (3/50).
On the other hand, the battery using the metal pseudo-porous body of the present invention had 0% short-circuit failure, indicating that the separator was not easily damaged.

Next, a description will be given of a battery of Comparative Example 2 which was experimentally manufactured in order to confirm the effect on the length of the short metal fiber in Example 3 according to the present invention. For the positive electrode plate of the battery of Comparative Example 2, a short metal fiber having a length of 0.7 mm was prepared, and, as in the battery of Example 3, at an angle of 50 degrees with the substrate,
A pseudo metal porous body prepared to have a similar density was used. An active material was applied to the metal pseudo-porous body so that the thickness after application was about 1 mm, and after drying, pressure treatment was performed to prepare a 0.9 mm thick positive electrode plate. This positive electrode plate and Example 3
A nickel-metal hydride storage battery was prepared in the same manner as in Example 3 using the negative electrode plate used in Example 3 to obtain a battery of Comparative Example 2. For the battery of Example 3 and the battery of Comparative Example 2, 290 mA (0.1 C
(equivalent to mA) for 15 hours, and left for 1 hour, and then examined for discharge characteristics. Initial discharge voltage is about 1.2V and 1.0V
The discharge amount was determined based on the time until the discharge time. Table 2 shows the results of comparing the discharge characteristics of the battery of Comparative Example 2 and the battery of Example 3.

[0046]

[Table 2]

When the amount of discharge is small, there is almost no difference between the battery of Comparative Example 2 and the battery of Example 3, but when the amount of discharge is large, the battery of Example 3 has excellent discharge characteristics. You can see that This is due to the difference in the contact area with the active material.

[0048]

As is apparent from the detailed description of the embodiments, the present invention has the following effects.
The metal porous body of the present invention, since the metal short fibers are inclined and stand substantially parallel to each other with respect to the substrate on the substrate, filling the active material along the direction of the inclination, pressurizing. When the battery electrode plate is formed, it is possible to eliminate projections on the surface of the metal pseudo-porous body after filling the active material. Therefore, when a battery is manufactured using the battery electrode plate of the present invention, there is an effect that damage to the separator is prevented and a short circuit between the electrode plates is eliminated. In addition, by making the height of the short metal fibers higher than the thickness of the active material coating layer, the contact area between the short metal fibers and the active material can be increased, so that the effect of not deteriorating the discharge characteristics at a large current can be obtained. Have.

[Brief description of the drawings]

FIG. 1 is a side view showing a pseudo metal porous body of Example 1 according to the present invention.

FIG. 2 is a process diagram of a manufacturing process of short metal fibers used for a pseudo-porous metal body of Example 1 according to the present invention.

FIG. 3 shows a short metal fiber obtained by performing composite spinning of another embodiment used for the pseudo-porous metal body of Example 1 according to the present invention;
(A) is a longitudinal sectional view of a short metal fiber, and (b) is a transverse sectional view of a short metal fiber.

FIG. 4 is a view showing a process for manufacturing a pseudo-porous metal body of Example 1 according to the present invention.

FIG. 5 is a view showing a step of filling and applying an active material in the production of the battery electrode of Example 2 according to the present invention.

FIG. 6 is a cross-sectional view showing the relationship between the length of a short metal fiber and the thickness of an active material in a battery electrode of Example 2 according to the present invention.

FIG. 7 is a cross-sectional view showing a pressurizing step in the manufacture of the battery electrode of Example 2 according to the present invention.

8A is a view showing a step of filling a conventional pseudo-porous metal body with an active material, and FIG. 8B is a view showing a step of filling a conventional pseudo-porous metal body with an active material by short metal fibers. It is a figure showing the state where it was separated from.

FIG. 9 (a) is a view showing a step of subjecting a conventional pseudo-porous metal filled with an active material to a pressure treatment, and FIG. 9 (b) is a view showing metal short fibers alternately compressed during the conventional pressure step. (C) is a diagram showing metal short fibers protruding from the surface during a conventional pressing step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Metal short fiber 4 Core part 5 Sheath part 6 Kneading process 7 Pellet molding process 8 Heat melting process 9 Spinning process 10 Cutting process

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (5)

[Claims] 1. A fiber axis of a short fibrous metal material (hereinafter, referred to as a metal short fiber in each of the following claims) on a substrate substantially parallel to each other at a predetermined angle with respect to the substrate. A pseudo-porous metal body formed by being inclined and oriented. A step of forming an adhesive layer on the surface of the substrate, and dropping short metal fibers having magnetism from above the substrate on which the adhesive layer is formed while applying a magnetic field to the substrate on which the adhesive layer is formed; Causing the fiber axes of the short metal fibers to stand in a predetermined direction with respect to the substrate so as to be substantially parallel to each other; and applying a magnetic field to the substrate in which the short metal fibers stand substantially in parallel to each other. Curing the adhesive layer while fixing the short metal fibers to the substrate in a state where the short metal fibers are inclined and substantially parallel to each other in a forest. And a method of producing a pseudo-porous metal material. 3. An electrode plate for a battery in which an active material is filled in the pseudo metal porous body according to claim 1, wherein the active material layer has a thickness of the metal pseudo porous body. The metal electrode plate is formed to be thinner than the height of the metal short fiber from the substrate, the metal short fiber protruding from the active material layer is bent in an inclined direction, and the battery electrode plate is formed to a predetermined thickness. Battery electrode plate. 4. An active material is applied to the metal pseudo-porous body according to claim 1 along an inclined direction of the short metal fibers that stand in a direction substantially parallel to each other with respect to the substrate.
A step of forming an active material layer having a thickness lower than the height of the short metal fibers, performing a compression process along an inclined direction of the short metal fibers, bending the short metal fibers onto the active material layer, and Forming a battery electrode plate having a thickness of 3 mm. 5. A battery using the battery electrode plate according to claim 3 at least for a positive electrode.