WO2025057401A1 - Hydrogen storage material, method for producing same, and hydrogen container - Google Patents

Abstract

A hydrogen storage material (1) comprises: a porous metal body (2) having pores (21); and hydrogen storage alloy particles (3) that comprise a hydrogen storage alloy and are held in the pores (21) of the porous metal body (2). A portion of the surface of a hydrogen storage alloy particle (3) may be separated from the porous metal body (2). The hydrogen storage alloy particles (3) may be movably held in the pores (21) of the porous metal body (2). The porous metal body (2) may be a sintered material of a metal powder. The porous metal body (3) may have a three-dimensional network structure comprising columnar struts and a hub in which a plurality of struts are assembled.

Description

Hydrogen storage material, its manufacturing method and hydrogen container

The present invention relates to a hydrogen storage material, its manufacturing method, and a hydrogen container.

In recent years, there has been concern about the environmental burden caused by the use of fossil fuels, and hopes are being raised for the use of hydrogen, which has a lower environmental burden, as an energy source. In order to use hydrogen as an energy source, devices that include a hydrogen storage material that can reversibly store and release hydrogen are sometimes used. For example, Patent Document 1 describes a hydrogen tank that uses a hydrogen storage material to store hydrogen. Also, for example, Patent Document 2 describes a hydrogen boosting system that uses a hydrogen storage material to boost the hydrogen pressure.

JP 2007-309457 A JP 2019-19884 A

In hydrogen tanks and hydrogen boosting systems, powdered hydrogen storage alloys are often used as hydrogen storage materials. However, hydrogen storage alloys have the property of expanding when they absorb hydrogen and contracting when they release hydrogen. Furthermore, when powdered hydrogen storage alloys are filled into a container such as a hydrogen tank or hydrogen boosting system, the lower part of the container is densely packed with the hydrogen storage alloy, while a gap is created in the upper part of the container. In this way, if hydrogen is absorbed into the hydrogen storage alloy when the hydrogen storage alloy is unevenly arranged in the container, there is a risk that the expansion of the hydrogen storage alloy will apply high stress to the container.

In order to prevent problems caused by the expansion of the hydrogen storage alloy, a technology has been proposed in which resin is placed between the particles of the hydrogen storage alloy, and the resin is deformed when the hydrogen storage alloy expands, thereby relieving stress on the container. However, because resin has a relatively high thermal resistance, placing resin between the particles of the hydrogen storage alloy makes it difficult for the temperature of the hydrogen storage alloy to change. This creates the problem that it becomes difficult to quickly store hydrogen in the hydrogen storage alloy and release hydrogen from the hydrogen storage alloy.

The present invention was made in consideration of these problems, and aims to provide a hydrogen storage material that undergoes little volumetric change when hydrogen is stored and has excellent thermal conductivity, a manufacturing method thereof, and a hydrogen container equipped with this hydrogen storage material.

One aspect of the present invention is a metal porous body having pores,
The hydrogen storage body is made of a hydrogen storage alloy and has hydrogen storage alloy particles held within the pores of the metal porous body.

The hydrogen storage alloy particles in the hydrogen storage body are held within the pores of the metal porous body. Therefore, even when hydrogen is absorbed into the hydrogen storage alloy particles, the hydrogen storage alloy particles can expand within the pores. Therefore, the hydrogen storage body can reduce the amount of change in volume when hydrogen is absorbed.

The metal porous body also has high thermal conductivity. Therefore, when the temperature of the hydrogen absorbing body is changed, the temperature of the hydrogen storage alloy particles held in the pores of the metal porous body can be changed quickly. This allows hydrogen to be quickly absorbed into the hydrogen absorbing body and released from the hydrogen absorbing body.

As described above, the above embodiment makes it possible to provide a hydrogen storage material that undergoes little volumetric change upon hydrogen storage and has excellent thermal conductivity.

FIG. 1 is a partial cross-sectional view showing a main part of a hydrogen storage material according to a first embodiment. FIG. 2 is a partial cross-sectional view showing a main part of a compact of a mixture in the manufacturing method of a hydrogen absorbing material according to the first embodiment. FIG. 3 is a partial cross-sectional view showing a main portion of the hydrogen absorbing material according to the second embodiment. FIG. 4 is a partial cross-sectional view showing a main part of a resin foam in the manufacturing method of a hydrogen storage material according to the second embodiment. FIG. 5 is a SEM image of the surface of the hydrogen storage material in the experimental example. FIG. 6 is an enlarged SEM image of the opening of the pore in FIG. FIG. 7 is a partial cross-sectional view showing a main portion of a hydrogen container according to the third embodiment.

(Embodiment 1)
An embodiment of the hydrogen storage material will be described with reference to Figures 1 and 2. As shown in Figure 1, the hydrogen storage material 1 of this embodiment has a metal porous body 2 having pores 21, and hydrogen storage alloy particles 3 made of a hydrogen storage alloy and held in the pores 21 of the metal porous body 2.

[Metal Porous Body 2]
The metal porous body 2 is made of metal and has pores 21 that hold the hydrogen storage alloy particles 3. As shown in Fig. 1, the pores 21 of the metal porous body 2 may have an accommodation space 211 in which the hydrogen storage alloy particles 3 are accommodated, and a connection space 212 that connects the accommodation space 211 to the outside of the metal porous body 2. For example, the metal porous body 2 of this embodiment is made of a sintered product of metal powder 22, and the voids between the metal particles 221 that constitute the metal powder 22 constitute the connection space 212 of the pores 21. In addition, voids are formed around the hydrogen storage alloy particles 3 in the metal porous body 2, and the voids around the hydrogen storage alloy particles 3 constitute the accommodation space 211 of the pores 21.

Therefore, the hydrogen absorbing body 1 of this embodiment can guide hydrogen supplied from outside the metal porous body 2 to the hydrogen storage alloy particles 3 via the connection space 212 and the storage space 211 of the pores 21, and store it in the hydrogen storage alloy particles 3. The hydrogen absorbing body 1 can also guide hydrogen released from the hydrogen storage alloy particles 3 to the outside of the metal porous body 2 via the storage space 211 and the connection space 212 of the pores 21.

The average particle diameter of the metal particles 221 that make up the metal powder 22 can be set appropriately, for example, within the range of 0.1 μm or more and 20 μm or less.

When the metal porous body 2 is composed of a sintered product of metal powder 22, it is preferable that the average particle diameter of the metal particles 221 constituting the metal powder 22 is smaller than the average particle diameter of the hydrogen storage alloy particles 3. In this case, the metal powder 22 can be sintered at a lower temperature during the manufacturing process of the hydrogen storage body 1. Therefore, the metal porous body 2 can be formed while suppressing deterioration of the hydrogen storage alloy particles 3 due to heating during sintering. From the viewpoint of more reliably obtaining such an effect, it is preferable that the average particle diameter of the metal particles 221 constituting the metal powder 22 is 1/2 or less, more preferably 1/5 or less, and even more preferably 1/10 or less, of the average particle diameter of the hydrogen storage alloy particles 3.

The average particle diameter of the metal particles 221 and the average particle diameter of the hydrogen storage alloy particles 3 described above are median diameters (i.e., cumulative 50% particle diameters) determined based on volumetric particle size distribution. The volumetric particle size distribution can be obtained, for example, using a laser diffraction/scattering type particle size measuring device.

The pores 21 of the metal porous body 2 preferably have a continuous pore structure, that is, a structure in which each pore 21 is connected to other pores 21. In this case, hydrogen can flow more easily throughout the hydrogen storage body 1, so the amount of hydrogen stored in the hydrogen storage body 1 can be increased.

The metal constituting the metal porous body 2 may be any metal other than a hydrogen storage alloy, that is, any metal that cannot reversibly absorb and release hydrogen. More specifically, the metal constituting the metal porous body 2 may be iron, iron alloys, copper, copper alloys, aluminum, aluminum alloys, nickel, nickel alloys, etc.

The metal constituting the metal porous body 2 preferably has a melting point lower than that of the hydrogen storage alloy. In this case, when producing the hydrogen storage body 1, the metal porous body 2 can be formed while suppressing deterioration of the hydrogen storage alloy particles 3 due to heating.

[Hydrogen storage alloy particles 3]
The hydrogen storage alloy particles 3 are made of a hydrogen storage alloy and are held within the pores 21 of the metal porous body 2. It is preferable that a part of the surface of the hydrogen storage alloy particles 3 is separated from the metal porous body 2. By providing a gap between the hydrogen storage alloy particles 3 and the metal porous body 2 in this manner, when the hydrogen storage alloy particles 3 absorb hydrogen, it is possible to more easily prevent the hydrogen storage alloy particles 3 from expanding outward beyond the pores 21 of the metal porous body 2 and deforming the metal porous body 2. Therefore, in this case, it is possible to more easily suppress the expansion of the hydrogen storage body 1 when hydrogen is absorbed.

The hydrogen storage alloy particles 3 may be fixed to the inner surface of the metal porous body 2, but are preferably held movably within the pores 21 of the metal porous body 2. In this case, too, it is easier to prevent the hydrogen storage alloy particles 3 from expanding beyond the pores 21 of the metal porous body 2 when the hydrogen storage alloy particles 3 absorb hydrogen. Therefore, in this case, it is easier to suppress the expansion of the hydrogen storage body 1 when hydrogen is absorbed.

There are no particular limitations on the composition of the hydrogen storage alloy constituting the hydrogen storage alloy particles 3. Examples of the hydrogen storage alloy that can be used to form the hydrogen storage alloy particles 3 include _AB5 type rare earth alloys such as _LaNi5 and mischmetal-nickel alloys, AB2 _type Laves phase alloys such as _MgZn2 and _ZrNi2 , AB type titanium alloys such as TiFe and TiCo, _A2B type magnesium alloys such as _Mg2Ni and _Mg2Cu , and solid solution type BCC alloys such as Ti-V alloys and Ti-Cr alloys.

The average particle diameter of the hydrogen storage alloy particles 3 can be set appropriately, for example, within the range of 1 μm or more and 200 μm or less.

[Method for manufacturing hydrogen storage material 1]
In manufacturing the hydrogen absorbing material 1 of this embodiment, for example, a pore-forming material is attached to the surface of the hydrogen storage alloy particles 3,
Thereafter, the hydrogen storage alloy particles 3 and the metal powder 22 that will become the metal porous body 2 are mixed to prepare a mixture,
The mixture is molded to produce a molded body 10 shown in FIG.
The compact 10 may be heated to remove the pore-forming material 213 and sinter the metal powder 22 to form the metal porous body 2 .

In this way, by heating the hydrogen storage alloy particles 3 to which the pore-forming material 213 has been previously attached together with the metal powder 22 and removing the pore-forming material 213, it is possible to form voids between the hydrogen storage alloy particles 3 and the metal porous body 2 while retaining the hydrogen storage alloy particles 3 in the pores 21 of the metal porous body 2.

In this embodiment of the manufacturing method, first, the pore-forming material 213 is attached to the surface of the hydrogen storage alloy particle 3. As the pore-forming material 213, a substance that can be thermally decomposed at a temperature lower than the melting point of the hydrogen storage alloy particle 3 can be used. More specifically, as the pore-forming material 213, an organic polymer such as an acrylic resin, a styrene-based resin, or a urethane resin can be used. From the viewpoint of more reliably forming voids around the hydrogen storage alloy particle 3, it is preferable that the thermal decomposition temperature of the pore-forming material 213 is lower than the sintering temperature of the metal powder 22.

The form of the pore-forming material 213 is not particularly limited. For example, the pore-forming material 213 may be in the form of a film or particles. The pore-forming material 213 may also be adhered to the surface of the hydrogen storage alloy particles 3 via a pore-forming assistant made of an organic substance. As the pore-forming assistant, for example, an organic polymer having adhesive properties such as polyvinyl acetate can be used. It is preferable that the thermal decomposition temperature of the pore-forming assistant is lower than the sintering temperature of the metal powder 22.

The amount of the pore-forming material 213 attached is preferably 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of the hydrogen storage alloy particles 3, more preferably 3 parts by mass or more and 40 parts by mass or less, even more preferably 5 parts by mass or more and 30 parts by mass or less, and particularly preferably 7 parts by mass or more and 20 parts by mass or less.

By setting the amount of the pore-forming material 213 to be preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more per 100 parts by mass of the hydrogen storage alloy particles 3, the voids formed around the hydrogen storage alloy particles 3 can be appropriately widened. Also, by setting the amount of the pore-forming material 213 to be preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less per 100 parts by mass of the hydrogen storage alloy particles 3, the amount of the hydrogen storage alloy particles 3 held in the hydrogen storage body 1 can be increased, and the amount of hydrogen that can be absorbed in the hydrogen storage body 1 can be increased. Also, in this case, it is easy to avoid the volume ratio of the pores in the metal porous body 2 becoming excessively high. As a result, it is easy to avoid a decrease in the strength of the metal porous body 2.

Next, the hydrogen storage alloy particles 3 with the pore-forming material 213 attached thereto are mixed with the metal powder 22 that will become the metal porous body 2 to produce a mixture. The content of the hydrogen storage alloy particles 3 in the mixture is preferably 40% by mass or more and 90% by mass or less, more preferably 45% by mass or more and 85% by mass or less, even more preferably 50% by mass or more and 80% by mass or less, and particularly preferably 55% by mass or more and 75% by mass or less, based on the total mass of the hydrogen storage alloy particles 3 and the mass of the metal powder 22.

By setting the content of hydrogen storage alloy particles 3 in the mixture to preferably 40 mass% or more, more preferably 45 mass% or more, even more preferably 50 mass% or more, and particularly preferably 55 mass% or more, based on the total mass of hydrogen storage alloy particles 3 and metal powder 22, the amount of hydrogen storage alloy particles 3 held in hydrogen storage body 1 can be increased, and the amount of hydrogen that can be stored in hydrogen storage body 1 can be increased.

Furthermore, by setting the content of the hydrogen storage alloy particles 3 in the mixture to preferably 90 mass% or less, more preferably 85 mass% or less, even more preferably 80 mass% or less, and particularly preferably 75 mass% or less, based on the total mass of the hydrogen storage alloy particles 3 and the mass of the metal powder 22, it is possible to easily prevent the volume ratio of the pores in the metal porous body 2 from becoming excessively high. As a result, it is possible to more easily prevent a decrease in the strength of the metal porous body 2.

If necessary, a liquid dispersion medium for dispersing the hydrogen storage alloy particles 3 and metal powder 22 may be added to the mixture. By dispersing the hydrogen storage alloy particles 3 and metal powder 22 in a liquid dispersion medium and liquefying the mixture, the mixture can be more easily molded into the desired shape. As a result, a hydrogen storage body 1 of the desired shape can be obtained.

As a liquid dispersion medium, for example, liquid organic polymers such as polyalkylene oxides and polyvinyl alcohol, or solutions containing these organic polymers, etc. can be used.

After the mixture is prepared, it is molded into a desired shape to obtain a molded body 10. The molded body 10 thus obtained has a structure in which hydrogen storage alloy particles 3 with pore-forming material 213 attached thereto are embedded in metal powder 22, as shown in FIG. 2. There are no particular limitations on the method for molding the mixture, and an appropriate method may be selected from known methods such as press molding, injection molding, powder rolling, and gelation freezing depending on the properties of the mixture.

The molded body 10 thus obtained is heated at a temperature higher than the thermal decomposition temperature of the pore-forming material 213 and the sintering temperature of the metal powder 22, but lower than the melting point of the hydrogen storage alloy particles 3. When the molded body 10 is heated at such a temperature, the pore-forming material 213 attached to the periphery of the hydrogen storage alloy particles 3 disappears due to thermal decomposition, and voids are formed around the hydrogen storage alloy particles 3. In addition, the metal powder 22 present around the hydrogen storage alloy particles 3 is integrated to form the metal porous body 2. Therefore, by heating the molded body 10 at the aforementioned temperature, the hydrogen storage body 1 can be obtained.

As shown in FIG. 1, the hydrogen storage alloy particles 3 in the hydrogen storage body 1 of this embodiment are held within the pores 21 of the metal porous body 2. Therefore, even when hydrogen is absorbed in the hydrogen storage alloy particles 3, the hydrogen storage alloy particles 3 can expand within the pores 21. Therefore, the hydrogen storage body 1 can reduce the amount of change in volume when hydrogen is absorbed.

In addition, the metal porous body 2 of this embodiment has high thermal conductivity. Therefore, when the temperature of the hydrogen absorbing body 1 is changed, the temperature of the hydrogen storage alloy particles 3 held in the pores of the metal porous body 2 can be changed quickly. This allows hydrogen to be quickly absorbed into the hydrogen absorbing body 1 and released from the hydrogen absorbing body 1.

Therefore, the hydrogen storage material 1 of this embodiment undergoes little volume change due to hydrogen storage and has excellent thermal conductivity.

(Embodiment 2)
In this embodiment, another example of the hydrogen storage material will be described. In the following embodiments, the same reference numerals as those used in the previous embodiments represent the same components as those in the previous embodiments, unless otherwise specified.

The metal porous body 202 in the hydrogen storage body 102 of this embodiment has a three-dimensional mesh structure including columnar struts 23 and a hub 24 consisting of a group of multiple struts 23, as shown in an example in FIG. 3, and the gaps around the struts 23 and the hub 24 form the pores 21. The pores 21 in the metal porous body 202 are interconnected in parts not shown in FIG. 3. In other words, the metal porous body 202 has a continuous pore structure.

The hydrogen storage alloy particles 3 are held in the three-dimensional mesh structure of the metal porous body 202. Gaps are formed between the metal porous body 202 and the hydrogen storage alloy particles 3, and the gaps around the hydrogen storage alloy particles 3 in the pores 21 form the storage space 211. The parts of the pores 21 other than the storage space 211 form the connection space 212.

In producing the hydrogen absorbing material 102 of this embodiment,
A pore-forming material 213 is attached to the surface of the hydrogen storage alloy particle 3,
Thereafter, a resin foam 4 containing hydrogen storage alloy particles 3 and having an open pore structure as shown in FIG. 4 is produced.
A metal film that becomes the metal porous body 202 is formed on the surface of the cell wall 42 of the resin foam 4.
Thereafter, the resin foam 4 is heated to remove the pore-forming material 213 and the cell walls 42 , thereby forming the metal porous body 202 .

In the manufacturing method of this embodiment, first, the pore-forming material 213 is attached to the surface of the hydrogen storage alloy particle 3. The configuration of the hydrogen storage alloy particle 3, the configuration of the pore-forming material 213, and the amount of the pore-forming material 213 attached used in the manufacturing method of this embodiment are the same as those of the hydrogen storage alloy particle 3 and the pore-forming material 213 in embodiment 1.

Next, the hydrogen storage alloy particles 3 with the pore-forming material 213 attached thereto are mixed with an expandable resin, and the expandable resin is then expanded to produce a resin foam 4 containing the hydrogen storage alloy particles 3. The bubbles 41 of the resin foam 4 thus obtained have an open pore structure, that is, a structure in which multiple bubbles are interconnected. The bubble walls 42 of the resin foam 4 have a three-dimensional mesh structure having columnar struts 421 and hubs 422 in which multiple struts 421 are gathered, as shown in FIG. 4, for example. The hydrogen storage alloy particles 3 are held in a state where they are captured by the bubble walls 42 of the resin foam 4.

The foamable resin used to produce the resin foam 4 is not particularly limited, and any known foamable resin capable of forming a continuous pore structure can be used. For example, the resin constituting the resin foam 4 may be polyurethane, polyethylene, polystyrene, etc. Furthermore, the method for foaming the foamable resin is not particularly limited, and any known foaming method can be used.

The content of the hydrogen storage alloy particles 3 in the resin foam 4 is preferably within a range of, for example, 1 volume % to 55 volume % relative to the apparent volume of the resin foam 4, i.e., the volume of the resin foam 4 including the volume of the air bubbles 41.

By setting the content of hydrogen storage alloy particles 3 in the resin foam 4 to preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 30% by volume or more, relative to the apparent volume of the resin foam 4, the amount of hydrogen storage alloy particles 3 held in the hydrogen storage material 102 can be increased, and the amount of hydrogen that can be stored in the hydrogen storage material 102 can be increased.

The amount of hydrogen storage alloy particles 3 contained in the resin foam 4 can be adjusted by the mixing ratio of the expandable resin to the hydrogen storage alloy particles 3 and the expansion ratio of the expandable resin.

After the resin foam 4 containing the hydrogen storage alloy particles 3 and having a continuous pore structure is obtained as described above, a metal film is formed on the surface of the bubble walls 42 of the resin foam 4. There is no particular limitation on the method for forming the metal film on the surface of the bubble walls 42, but from the viewpoint of forming a metal film evenly over the entire resin foam 4, it is preferable to form the metal film on the surface of the bubble walls 42 by using a plating method. The metal constituting the metal film may be any metal other than the hydrogen storage alloy, that is, a metal that cannot reversibly absorb and release hydrogen, and that can form a metal film by a plating method. Examples of metals that can be used for the metal film include iron alloys, copper, copper alloys, chromium, chromium alloys, nickel, and nickel alloys.

Then, the molded body is heated at a temperature higher than the thermal decomposition temperature of the pore-forming material 213 and the thermal decomposition temperature of the bubble walls 42 in the resin foam 4 (i.e., the thermal decomposition temperature of the resin that constitutes the resin foam 4), but lower than the melting point of the hydrogen storage alloy particles 3. When the molded body is heated at such a temperature, the pore-forming material 213 attached to the periphery of the hydrogen storage alloy particles 3 disappears due to thermal decomposition, and voids are formed around the hydrogen storage alloy particles 3. In addition, the bubble walls 42 in the resin foam 4 disappear due to thermal decomposition, and a metal film remains, forming a metal porous body 202 having a three-dimensional mesh structure that reflects the shape of the bubble walls 42 in the resin foam 4.

As described above, the hydrogen storage material 102 having the above-described structure can also be obtained by heating the resin foam 4 containing the hydrogen storage alloy particles 3 and removing the pore-forming material 213 and the cell walls 42 of the resin foam 4.

(Experimental Example)
In this example, an example of producing a hydrogen storage material in embodiment 1 using hydrogen storage alloy particles made of _LaNi5 and having a particle diameter of 100 μm and metal powder made of stainless steel and having an average particle diameter of 3 μm is described.

In this example, first, polyvinyl acetate was dissolved in acetone as a pore-forming aid to prepare a pore-forming aid solution with a concentration of 5% by mass. Next, 50 parts by mass of the pore-forming aid solution was added to 100 parts by mass of hydrogen storage alloy particles, and the mixture was thoroughly mixed and then dried to adhere the pore-forming aid to the surface of the hydrogen storage alloy particles.

Next, a pore-forming material was added to the hydrogen storage alloy particles and mixed thoroughly to adhere the pore-forming material to the surface of the hydrogen storage alloy particles. The pore-forming material used was spherical resin particles made of polymethyl methacrylate and having an average particle size of 10 μm ("Ganz Pearl (registered trademark) GM-1001" manufactured by Aica Kogyo Co., Ltd.). The amount of pore-forming material was 10 parts by mass per 100 parts by mass of hydrogen storage alloy particles before the pore-forming aid was attached.

In addition to preparing the hydrogen storage alloy particles, a dispersion medium with a polyvinyl alcohol concentration of 10 mass % was prepared by dissolving polyvinyl alcohol in distilled water.

The hydrogen storage alloy particles thus obtained were mixed with a metal powder and a dispersion medium to produce a slurry-like mixture. The amount of metal powder in the mixture was 66 parts by mass per 100 parts by mass of hydrogen storage alloy particles before the pore-forming material was attached. The amount of binder solution in the mixture was 59 parts by mass per 100 parts by mass of hydrogen storage alloy particles before the pore-forming material was attached.

The mixture obtained in this manner was poured into a rectangular molding die 50 mm long, 10 mm wide, and 5 mm thick, and then cooled to a temperature of -18°C or lower. This caused the mixture in the container to gel, resulting in a molded body. This molded body was dried to remove the distilled water, and then heated in an inert gas atmosphere at a temperature of 500°C for two hours to thermally decompose the pore-forming material, pore-forming aid, and polyvinyl alcohol in the molded body. The molded body was then heated at a temperature of 750°C for three hours to sinter the metal powder and form a metal porous body. In this manner, a hydrogen storage body was obtained.

Figures 5 and 6 show an example of an SEM image of the surface of a hydrogen storage body 103 obtained by observing the surface of the hydrogen storage body using a scanning electron microscope. As shown in Figure 5, the hydrogen storage body 103 has a metal porous body 2 with a large number of pores 21, and it can be seen that the pores 21 are open on the surface of the metal porous body 2. It can also be seen that within the metal porous body 2 there are hydrogen storage alloy particles 3, which are shown in a lighter color tone than the metal powder 22 that constitutes the metal porous body 2.

When the openings on the surface of the metal porous body 2 are enlarged, as shown in Figure 6, it can be seen that hydrogen storage alloy particles 3 are held within the pores 21, with gaps being formed between the hydrogen storage alloy particles 3 and the metal porous body 2. Furthermore, it can be seen that the metal porous body 2 is made of a sintered body of metal powder 22, and gaps are also formed between the metal particles that make up the metal powder 22.

As described above, the method of this example made it possible to obtain a hydrogen storage body that includes a metal porous body having pores and hydrogen storage alloy particles that are made of a hydrogen storage alloy and are held within the pores of the metal porous body.

(Embodiment 3)
In this embodiment, an example of the application of the hydrogen absorbing material 1 will be described. The hydrogen absorbing material 1 may be applied to hydrogen-related equipment configured to be capable of reversibly absorbing and releasing hydrogen. For example, the hydrogen absorbing material 1 of this embodiment is used in a hydrogen container 5 configured to be capable of reversibly absorbing and releasing hydrogen, as shown in FIG. 7.

The hydrogen container 5 has a container body 51 with a storage space 511 for storing hydrogen gas, a hydrogen storage body 1 arranged in the storage space 511, and a temperature adjustment means 52 configured to change the temperature of the hydrogen storage body 1.

The container body 51 of the hydrogen container 5 is configured to hold hydrogen supplied from outside the hydrogen container 5 and hydrogen released from the hydrogen absorbing body 1 in the storage space 511. The container body 51 has at least one hydrogen port 53 configured to communicate the outside of the hydrogen container 5 with the storage space 511. The hydrogen port 53 is configured to communicate the external space with the storage space 511, thereby allowing hydrogen to be supplied from the outside of the hydrogen container 5 to the storage space 511 and/or hydrogen to be released from the hydrogen container 5 to the outside. The number of hydrogen ports 53 provided on the container body 51 may be one or two or more. For example, the container body 51 of this embodiment has one hydrogen port 53 as shown in FIG. 7, and is configured so that the hydrogen port 53 can be used for both supplying hydrogen from the outside of the hydrogen container 5 to the storage space 511 and releasing hydrogen from the hydrogen container 5 to the outside.

The shape of the container body 51 is not particularly limited, and various shapes such as a cylindrical shape, a spherical shape, a box shape, etc. can be adopted. For example, the container body 51 of this embodiment has a cylindrical shape as shown in FIG. 7.

The volume of the container body 51 is preferably 300 ^m3 or less. The smaller the volume of the container body 51, the greater the pressure fluctuations that occur when hydrogen is released from the hydrogen container 5. Therefore, by making the volume of the container body 51 300 ^m3 or less, the effect of suppressing the pressure fluctuations that occur when hydrogen is released can be made more effective. Furthermore, by making the volume of the container body 51 300 ^m3 or less, the hydrogen container 5 can be easily made smaller, and restrictions on the installation location can be reduced.

Moreover, the maximum value of the internal pressure of the container body 51 is preferably 1 MPa (G) or less in terms of gauge pressure. By setting the volume of the container body 51 to 300 ^m3 or less and setting the maximum value of the internal pressure of the container body 51 to 1 MPa (G) or less, the safety of the container body 51 can be improved and the maintenance of the container body 51 can be further simplified.

Hydrogen storage bodies 1 are provided in the storage space 511 of the container body 51. The number, shape, arrangement, etc. of the hydrogen storage bodies 1 provided in the container body 51 are not particularly limited, and can be set appropriately depending on the desired maximum hydrogen storage amount and the pressure when releasing hydrogen from the hydrogen container 5, etc.

The temperature adjustment means 52 can change the temperature of the hydrogen absorbing body 1, release hydrogen absorbed in the hydrogen absorbing body 1 from the hydrogen absorbing body 1 to the storage space 511, or absorb hydrogen in the storage space 511 into the hydrogen absorbing body 1. The method of changing the temperature of the hydrogen absorbing body 1 in the temperature adjustment means 52 is not particularly limited and can take various forms. For example, the temperature adjustment means 52 in this embodiment is configured to be able to change the temperature of the hydrogen absorbing body 1 by heating or cooling the entire container body 51. Therefore, for example, by increasing the temperature of the hydrogen absorbing body 1 with the temperature adjustment means 52, hydrogen can be released from the hydrogen absorbing body 1 to the storage space 511. Also, for example, by lowering the temperature of the hydrogen absorbing body 1, hydrogen in the storage space 511 can be absorbed into the hydrogen absorbing body 1.

As mentioned above, the hydrogen storage alloy particles 3 in the hydrogen storage body 1 are held within the pores 21 of the metal porous body 2. Therefore, the hydrogen storage body 1 can reduce the amount of change in volume when hydrogen is absorbed. Therefore, by applying the hydrogen storage body 1 to the hydrogen container 5 as in this embodiment, the load applied to the container body 51 when hydrogen is absorbed into the hydrogen storage body 1 can be more easily reduced, making it less likely that distortion will occur in the container body 51. Furthermore, in this case, hydrogen can be stored more efficiently in the hydrogen container 5.

The hydrogen storage body 1 used in the hydrogen container 5 preferably has hydrogen storage alloy particles made of a TiFe-based hydrogen storage alloy. TiFe-based hydrogen storage alloys are easy to handle, so by applying hydrogen storage alloy particles made of a TiFe-based hydrogen storage alloy to the hydrogen storage body 1 of the hydrogen container 5, the safety of the hydrogen container 5 can be further improved. In addition, since TiFe-based hydrogen storage alloys are relatively inexpensive among hydrogen storage alloys, further reductions in the cost of the hydrogen container 5 can be expected.

The TiFe-based alloys mentioned above include TiFe binary alloys and TiFe-based multi-component alloys in which part of the Ti and/or Fe in the TiFe binary alloy is replaced with another element. The TiFe-based alloy may be, for example, a TiFeMn ternary alloy in which part of the Fe in the TiFe binary alloy is replaced with Mn. The TiFe-based alloy may also be a multi-component alloy in which another metal element is further added to the TiFeMn ternary alloy.

　Although the above describes the hydrogen storage body and the manufacturing method thereof based on the embodiment and experimental examples, the specific aspects of the hydrogen storage body and the manufacturing method thereof according to the present invention are not limited to the above embodiments and experimental examples, and the configuration can be changed as appropriate within the scope of the gist of the present invention.

Claims (9)

A metal porous body having pores;
a metal porous body having a porous metal layer and a porous metal layer formed on the porous metal layer; The hydrogen storage material according to claim 1, wherein a portion of the surface of the hydrogen storage alloy particles is separated from the metal porous body. The hydrogen storage body according to claim 1, wherein the hydrogen storage alloy particles are movably held within the pores of the metal porous body. The hydrogen storage material according to any one of claims 1 to 3, wherein the metal porous body is a sintered metal powder. The hydrogen storage material according to any one of claims 1 to 3, wherein the metal porous body has a three-dimensional mesh structure consisting of columnar struts and a hub where multiple struts are gathered. A method for producing a hydrogen storage material according to claim 4, comprising the steps of:
A pore-forming material is attached to the surface of the hydrogen storage alloy particles,
Then, the hydrogen storage alloy particles are mixed with a metal powder that will become the metal porous body to prepare a mixture;
The mixture is molded to produce a molded body;
a step of heating the compact to remove the pore-forming material and sinter the metal powder to form the metal porous body. A method for producing a hydrogen storage material according to claim 5,
A pore-forming material is attached to the surface of the hydrogen storage alloy particles,
Then, a resin foam containing the hydrogen storage alloy particles and having an open pore structure is produced,
forming a metal film that will become the metal porous body on the surface of the cell walls of the resin foam;
Thereafter, the resin foam is heated to remove the pore-forming material and the cell walls, thereby forming the metal porous body. A hydrogen container equipped with a hydrogen storage material according to any one of claims 1 to 3. The hydrogen container according to claim 8, wherein the hydrogen storage alloy particles in the hydrogen storage body are composed of a TiFe-based hydrogen storage alloy.

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