JP2008531445A - Hydrogen storage structure - Google Patents

Abstract

【Task】
Provided is a hydrogen storage structure having a large hydrogen storage amount and a high hydrogen storage rate near room temperature.
A hydrogen storage structure includes a hydrogen storage layer including Mg or an Mg-based hydrogen storage alloy, and a hydrogen diffusion layer provided so as to sandwich the hydrogen storage layer and including a hydrogen diffusion material. A plurality of hydrogen storage layers including Mg or Mg-based hydrogen storage alloy and a plurality of hydrogen diffusion layers including a hydrogen diffusion material are alternately provided. The hydrogen equilibrium pressure at 25 ° C. of the hydrogen diffusing material is 0.1 MPa or higher and higher than the hydrogen equilibrium pressure at 25 ° C. of Mg or the Mg-based hydrogen storage alloy. The hydrogen diffusing material is at least one selected from TiMn, TiCr, TiFe, Ti and V. Furthermore, you may provide the hydrogen dissociation layer containing a hydrogen dissociation material as an outermost layer.
[Selection] Figure 6

Description

  The present invention relates to a hydrogen storage structure having a laminated structure.

  Due to the recent increase in environmental and energy problems, fuel cell vehicles are being actively developed. In developing a fuel cell vehicle, storage of hydrogen gas is regarded as one of the major issues, and development of a high-density hydrogen storage material for a fuel cell vehicle is required.

  As an example of the hydrogen storage material, a room temperature storage material represented by a TiCrV-based hydrogen storage alloy can be given. However, the development of TiCrV-based hydrogen storage alloys is stagnant with a hydrogen storage capacity of more than 2 mass%. In contrast, attempts have been made to use lightweight elements typified by Mg and the like because of the large amount of hydrogen stored. However, although Mg-based hydrogen storage alloys have a large amount of hydrogen storage, they require a high temperature of 350 ° C or higher for hydrogen storage / release, and the hydrogen storage / release rate is slow, so they are not suitable for practical use. is doing. For this reason, various attempts have been made to improve the hydrogen storage / release characteristics of Mg-based hydrogen storage alloys. For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2002-105576), magnesium or a magnesium-based alloy is used. A hydrogen storage layered structure including a thinned hydrogen storage layer and a pair of hydrogen transfer layers stacked so as to sandwich the hydrogen storage layer is disclosed. Patent Document 2 (Japanese Patent Laid-Open No. 2004-66653) and Patent Document 3 (Japanese Patent Laid-Open No. 2004-346418) disclose a technique related to a multilayer structure of a hydrogen storage material.

  The hydrogen storage layered structure disclosed in Japanese Patent Application Laid-Open No. 2002-105576 is provided with hydrogen transfer layers functioning as catalyst layers that dissociate hydrogen gas into atoms on both sides of a hydrogen storage layer made of magnesium or the like. is there. And as an Example, the hydrogen storage laminated structure of the three-layer structure which provided a pair of palladium layer on both sides of the magnesium layer is mentioned. However, it cannot be said that the hydrogen occlusion speed of this hydrogen occlusion laminated structure near room temperature is sufficient.

  A hydrogen storage laminated structure having a structure in which Mg or Mg-based hydrogen storage alloy described in Examples of Japanese Patent Application Laid-Open No. 2002-105576 is sandwiched between Pd layers, and a multilayer structure hydrogen storage body described in Japanese Patent Application Laid-Open No. 2004-66653 In addition, it is difficult to perform high-speed hydrogen absorption / desorption at 350 ° C. or lower by simply stacking a hydrogen storage material such as the multilayer structure described in Japanese Patent Application Laid-Open No. 2004-346418.

The hydrogen storage material may be used at a predetermined particle size, but the bulk density of the granular material is about 60% of the true density, so that the bulk density is significantly reduced when a light alloy such as magnesium is used. Become. Therefore, it is difficult to significantly improve the hydrogen storage amount per volume.
JP 2002-105576 A JP 2004-66653 A JP 2004-346418 A

  The present invention has been made in view of the above-described conventional problems, and provides a hydrogen storage structure having a large hydrogen storage amount and a high hydrogen storage rate near room temperature.

  A first aspect of the present invention includes a hydrogen storage layer containing Mg or an Mg-based hydrogen storage alloy, and a pair of hydrogen diffusion layers provided so as to sandwich the hydrogen storage layer and including a hydrogen diffusion material. It is a hydrogen storage structure.

  A second aspect of the present invention is a hydrogen storage structure comprising a plurality of hydrogen storage layers containing Mg or Mg-based hydrogen storage alloys and a plurality of hydrogen diffusion layers containing a hydrogen diffusion material alternately.

  In each of the above aspects, the hydrogen equilibrium pressure at 25 ° C. of the hydrogen diffusing material may be 0.1 MPa or higher and higher than the hydrogen equilibrium pressure at 25 ° C. of Mg or the Mg-based hydrogen storage alloy.

  In each of the above aspects, the hydrogen diffusing material may be at least one selected from TiMn, TiCr, TiFe, Ti, and V.

  In each of the above embodiments, the hydrogen diffusion material is stable against hydrogen, and the hydrogen diffusion coefficient at 25 ° C. of the hydrogen diffusion material is Mg at 25 ° C. or the hydrogen diffusion coefficient of the Mg-based hydrogen storage alloy Higher than that.

  In each of the above embodiments, the hydrogen diffusing material may be Ni.

  In each of the above aspects, a hydrogen dissociation layer including a hydrogen dissociation material may be further provided as the outermost layer.

  According to the present invention, it is possible to provide a hydrogen storage structure having a large hydrogen storage amount and a high hydrogen storage rate near room temperature.

Hereinafter, the hydrogen storage structure of the present invention will be described in detail.
FIG. 1 is a perspective view showing the hydrogen storage structure of the present invention according to the first embodiment. The hydrogen storage structure according to the first embodiment includes a hydrogen storage layer 1 containing Mg or an Mg-based hydrogen storage alloy, and a pair of hydrogen diffusion layers 2 provided to sandwich the hydrogen storage layer 1 and including a hydrogen diffusion material. And.

  The Mg or Mg-based hydrogen storage alloy contained in the hydrogen storage layer 1 is a material that has a high hydrogen storage capacity, but has a hydrogen storage / release temperature of 350 to 400 ° C., which is difficult to absorb and release at room temperature. The hydrogen diffusion material contained in the hydrogen diffusion layer 2 is a material having a high diffusion movement speed of hydrogen atoms. Hydrogen atoms enter the hydrogen diffusion layer 2 from the surface and end face of the hydrogen diffusion layer 2, diffuse and move at high speed in the hydrogen diffusion layer 2, and are formed into metal by Mg or Mg-based hydrogen storage alloy contained in the hydrogen storage layer 1. Stored as hydride. Therefore, the hydrogen storage structure of the present invention can store hydrogen at room temperature and at high speed. In addition, in this invention, room temperature means normal atmospheric temperature, and generally shows about 0-40 degreeC.

  In addition, Mg or Mg-based hydrogen storage alloy is easily oxidized and may react with oxygen or water to generate heat. However, since the hydrogen storage layer 1 is sandwiched between the pair of hydrogen diffusion layers 2, Mg or Mg-based hydrogen is used. The storage alloy is not directly exposed to the atmosphere, and the hydrogen storage structure of the present invention can be handled safely.

  Specific examples of the Mg-based hydrogen storage alloy used in the present invention include, for example, MgNi, MgAl, MgB and the like. The hydrogen storage layer 1 preferably contains a kind of hydrogen storage material selected from MgNi and Mg, and more preferably contains Mg.

  The hydrogen diffusing material used in the present invention is not particularly limited as long as it has a high diffusion rate of hydrogen atoms. For example, the hydrogen equilibrium pressure at 25 ° C. is 0.1 MPa or more, and Mg Or the material which shows a hydrogen equilibrium pressure higher than the hydrogen equilibrium pressure in 25 degreeC of the said Mg-type hydrogen storage alloy is preferable. By using such a material, the hydrogen dissociation property at room temperature can be improved, and the hydrogen storage temperature and the hydrogen storage rate can be greatly improved.

  Specific examples of materials having a hydrogen equilibrium pressure at 25 ° C. of 0.1 MPa or more and a hydrogen equilibrium pressure higher than that of Mg or the Mg-based hydrogen storage alloy at 25 ° C. include, for example, TiMn, TiCr At least one selected from TiFe, Ti and V.

  The hydrogen equilibrium pressure of the material can be determined from a PCT curve measured by a PCT (Pressure-Composition-Temperature).

  As the hydrogen diffusion material used in the present invention, a material that is stable against hydrogen and has a hydrogen diffusion coefficient at 25 ° C. higher than that of Mg or Mg-based hydrogen storage alloy at 25 ° C. is also preferable. In the present invention, the fact that the hydrogen diffusing material is stable against hydrogen means that the hydrogen diffusing material is stable to the extent that hydride is not formed in the environment where the hydrogen storage structure of the present invention is used.

  The hydrogen storage layer 1 contracts and expands when Mg or Mg-based hydrogen storage alloy stores and releases hydrogen. On the other hand, the hydrogen diffusion layer 2 containing a hydrogen diffusion material that is difficult to form a hydride also expands and contracts (changes in volume) to some extent. Therefore, the hydrogen storage layer 1 that has contracted by storing hydrogen has a tensile strain so that the volume of the hydrogen storage layer 1 hardly changes or the hydrogen storage layer 1 does not contract from the expanding hydrogen diffusion layer 2 so that the hydrogen storage is smooth. To be done. As a result, hydrogen storage at a low temperature can be realized.

  Specific examples of materials that are stable to hydrogen and have a hydrogen diffusion coefficient at 25 ° C. higher than that of Mg or Mg-based hydrogen storage alloys at 25 ° C. include Ni and the like.

  The hydrogen diffusion coefficient of the material can be measured by an electrochemical release method or a temperature programmed desorption method.

  10-1000 nm is preferable and, as for the film thickness of the hydrogen storage layer 1, 10-100 nm is more preferable. If the film thickness of the hydrogen storage layer 1 is 10 to 1000 nm, rapid hydrogen storage and release can be realized.

  The film thickness of the hydrogen diffusion layer 2 is preferably 1 to 150 nm, and more preferably 10 to 100 nm. If the film thickness of the hydrogen diffusion layer 2 is 1 to 150 nm, rapid hydrogen storage and release can be realized.

  The ratio A / B between the film thickness A of the hydrogen storage layer 1 and the film thickness B of the hydrogen diffusion layer 2 (the total film thickness of the two layers) B is preferably 1.5 or more, and more preferably 2 or more. If A / B is 1.5 or more, rapid hydrogen storage and release can be realized. In order to prevent a significant increase in the hydrogen storage time due to A / B being too large, A / B is preferably 10 or less.

  The shape, size, and the like of the hydrogen storage structure according to the first embodiment are not particularly limited, but the length in the short direction of the hydrogen storage structure is preferably 20 cm or less. By setting the length of the hydrogen storage structure in the short direction to 20 cm or less, rapid hydrogen storage and release can be realized.

  FIG. 2 is a perspective view showing the hydrogen storage structure of the present invention according to the second embodiment. The hydrogen storage structure according to the second embodiment further includes a hydrogen dissociation layer 3 including a hydrogen dissociation material in the outermost layer of the hydrogen storage structure of the present invention according to the first embodiment. The hydrogen storage structure according to the second embodiment includes the hydrogen dissociation layer 3 on both surfaces thereof, but may include the hydrogen dissipation layer 3 only on one surface.

  A hydrogen dissociation material is a material that exhibits a catalytic action that dissociates hydrogen molecules into hydrogen atoms. Specific examples of the hydrogen-dissociating material include V and Pd. Among these, Pd showing a strong catalytic action is preferable. By providing the hydrogen dissociation layer 3 in the outermost layer, rapid hydrogen storage can be realized.

  In the hydrogen storage structure according to the second embodiment, the hydrogen detaching layer 3 is made of a material that is superior in hydrogen detaching ability to the hydrogen diffusing material. The superiority or inferiority of the hydrogen dissociation ability of each material is known. For example, the hydrogen dissociation ability of Pd is superior to that of V. Therefore, when the hydrogen diffusion layer 2 is composed of V, the hydrogen dissociation layer 3 is composed of Pd.

  The film thickness of the hydrogen dissociation layer 3 is preferably 5 nm or less. If the thickness of the hydrogen dissociation layer 3 is 5 nm or less, rapid hydrogen storage and release can be realized.

  In addition, the preferable range and preferable materials of the film thickness of the hydrogen storage layer 1 and the hydrogen diffusion layer 2 in the hydrogen storage structure according to the second embodiment, the preferable range of the length in the short direction of the hydrogen storage structure, etc. This is the same as in the case of the first embodiment.

  FIG. 3 is a perspective view showing the hydrogen storage structure of the present invention according to the third embodiment. The hydrogen storage structure according to the third embodiment includes a plurality of hydrogen storage layers 1 containing Mg or an Mg-based hydrogen storage alloy and hydrogen diffusion layers 2 containing a hydrogen diffusion material alternately, and a hydrogen dissociation material in the outermost layer. The hydrogen dissociation layer 3 containing is further provided.

The hydrogen storage structure according to the third embodiment including a plurality of hydrogen storage layers than the hydrogen storage structure according to the first embodiment including a single hydrogen storage layer even when the total hydrogen storage layer has the same thickness. The body is superior in hydrogen storage rate and hydrogen storage capacity. This is considered to be because the contact area between the hydrogen diffusion layer 2 and the hydrogen storage layer 1 increases and the diffusion distance decreases when there are a plurality of hydrogen storage layers rather than a single layer. Unlike a so-called room temperature type hydrogen storage material, a hydrogen storage material such as Mg does not dissolve hydrogen but forms a hydride (ion bond) like MgH ₂ to store hydrogen. It is believed that the produced MgH ₂ itself hinders hydrogen diffusion and the subsequent hydrogen diffusion is significantly slowed when the material surface is hydrogenated. However, since the contact area between the hydrogen diffusing layer 2 and the hydrogen occluding layer 1 can be increased by providing a plurality of the hydrogen occluding layers 1 and the hydrogen diffusing layers 2 alternately, the hydrogen diffusing capacity is reduced due to hydrogenation of the material surface. It becomes difficult to be affected.

  When the hydrogen storage structure according to the third embodiment does not include the hydrogen separation layer 3, the outermost layer is preferably the hydrogen diffusion layer 2. By using the hydrogen diffusion layer 2 as the outermost layer, the hydrogen storage layer 1 containing Mg or an Mg-based hydrogen storage alloy can be handled safely without being in direct contact with the atmosphere.

  In the hydrogen storage structure according to the third embodiment, the total number of layers of the hydrogen storage layer 1 and the hydrogen diffusion layer 2 is preferably 10 layers or more, and particularly preferably 100 layers or more.

  10-100 nm is preferable and, as for the film thickness of the hydrogen storage layer 1, 10-50 nm is especially preferable. If the film thickness of the hydrogen storage layer 1 is 10 to 100 nm, rapid hydrogen storage and release can be realized.

  The film thickness of the hydrogen diffusion layer 2 is preferably 1 to 10 nm, and more preferably 1 to 5 nm. If the film thickness of the hydrogen diffusion layer 2 is 1 to 10 nm, rapid hydrogen storage and release can be realized.

  As for the film thickness of the hydrogen dissociation layer 3 provided as needed, 5 nm or less is preferable. If the thickness of the hydrogen dissociation layer 3 is 5 nm or less, rapid hydrogen storage and release can be realized.

  The ratio A / B of the film thickness A of the hydrogen storage layer 1 (the total film thickness of all the hydrogen storage layers 1) and the film thickness of the hydrogen diffusion layer 2 (the total film thickness of all the hydrogen diffusion layers 2) B is 1 The above is preferable, 5 or more is more preferable, and 10 or more is particularly preferable. If A / B is 1 or more, rapid hydrogen storage and release can be realized. In the case where the hydrogen dissociation layer 3 is provided, B means the total thickness of all the hydrogen diffusion layers 2 and all the hydrogen dissociation layers 3.

  Further, A / B is preferably 50 or less in order to prevent the hydrogen storage time from being several hours or more.

  In addition, the preferable range etc. of the length of the transversal direction in the hydrogen storage structure which concerns on 3rd embodiment are the same as that of the case of 1st embodiment.

  The method for producing the hydrogen storage structure of the present invention is not particularly limited, and may be produced using an already known thin film forming method such as sputtering or flash evaporation.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail with reference to an Example, this invention is not limited by the following Example.
-Production of hydrogen storage structure-
Hydrogen storage structure # 1 by laminating a hydrogen storage layer, a hydrogen diffusion layer and, if necessary, a hydrogen dissociation layer on an A4 size aluminum thin film using a multi-source sputtering apparatus based on the formulations described in Tables 1 to 5 Thru # 35 were produced.

-Measurement of hydrogen storage amount-
The amount of hydrogen occlusion was measured with a PCT apparatus.

  FIG. 4 is a diagram illustrating a schematic configuration of the PCT apparatus. In the apparatus 10, a hydrogen cylinder 11, a buffer container 12, a sample container 13, a vacuum pump 14, a pressure gauge 15, and a wet flow meter 18 are connected via a pipe 16. The piping 16 is provided with valves V0 to V6. The sample container 13 is covered with a heater 19 so that the hydrogen storage structure (for example, the measurement sample 17) in the sample container 13 is heated.

  First, with the valves V0, V5, and V6 closed and the valves V1 to V4 opened, the vacuum pump 14 is operated until the pressure in the buffer container 12, the sample container 13, and the pipe 16 is equal to or lower than a predetermined pressure.

  When the pressure in the buffer container 12, the sample container 13 and the pipe 16 becomes a predetermined pressure or less, the valve V3 is closed and the vacuum pump 14 is stopped.

  After the valve V2 is closed and the valve V0 is opened to fill the buffer container 12 with hydrogen gas, the valve V0 and the valve V1 are closed. At this time, the pressure measured by the pressure gauge 15 is P0. Next, the valve V2 is opened to make the pressure in the buffer container 12 and the sample container 13 constant. At this time, the pressure measured by the pressure gauge 15 is defined as P1. The hydrogen storage amount (mass%) is obtained from the pressure difference between the pressures P0 and P1. This method is generally known as the Siebert method (capacitance method).

-Measurement of released hydrogen amount-
In the apparatus 10 shown in FIG. 4, a measurement sample 17 in which hydrogen is occluded is placed in a sample container 13 heated to a predetermined temperature by a heater 19, valves V0 to V2, V4 and V5 are closed, and valves V3 and V6 are closed. In an open state, hydrogen released at each temperature was introduced into the wet flow meter 18 and the hydrogen volume was measured to determine the amount of hydrogen released.

  Further, the volume storage density was determined based on the obtained amount of released hydrogen. Here, the volume storage density refers to the volume of hydrogen gas stored per unit volume of the hydrogen storage structure.

  For the hydrogen storage structures # 1 to # 4 manufactured by the above-described method, 90% hydrogen storage time (storage time) and 90% hydrogen release time (release time) at a predetermined temperature were determined. The obtained results are shown in Table 1. The 90% hydrogen storage time refers to the time required to store 90% of the maximum hydrogen storage amount, and the 90% hydrogen release time refers to 90% of the maximum hydrogen storage amount. The time required for the amount of hydrogen released.

  As shown in Table 1, the hydrogen storage structures # 1 to # 3 according to the present invention can absorb hydrogen at 150 ° C. and release hydrogen at 300 ° C. It can be seen that the hydrogen storage characteristics and the hydrogen release characteristics are improved as compared with the hydrogen storage structure # 4 which is an Mg thin film.

  With respect to hydrogen storage structures # 5 (same as # 1) to # 7 manufactured by the above-described method, 90% hydrogen storage time (storage time) and 90% hydrogen release time (release time) at a predetermined temperature were determined. The obtained results are shown in Table 2.

  Table 2 shows that the hydrogen release temperature can be reduced by reducing the thickness of the hydrogen storage layer.

  For the hydrogen storage structures # 8 to # 18 produced by the above-described method, the hydrogen storage amount, volume storage density, and 90% hydrogen storage time at 25 ° C. were determined. The obtained results are shown in Table 3.

  Table 3 shows that hydrogen storage is possible at 25 degreeC. Further, the following can be understood.

(1) From the results of the hydrogen storage structures # 8 to # 10, it is understood that the occlusion time can be shortened by reducing the thickness of the hydrogen occlusion layer when no hydrogen dissociation layer is provided.

(2) From the results of the hydrogen storage structures # 11 to # 13, when no hydrogen dissociation layer is provided, the hydrogen storage layer has a thickness of 100 nm or more (and A / B is 2 or more). It can be seen that the amount of occlusion is large and the 90% hydrogen occlusion time is shortened.

(3) From the results of the hydrogen storage structures # 14 to # 17, the hydrogen storage amount at 25 ° C., the volume storage density, and 90 by setting A / B to 1.7 to 2.6 when a hydrogen dissociation layer is provided. It can be seen that a hydrogen storage structure excellent in% hydrogen storage time can be obtained.

(4) From the results of the hydrogen storage structures # 17 and # 18, it can be seen that there is a difference in the hydrogen storage rate depending on the presence or absence of the hydrogen dissociation layer (Pd).

  For the hydrogen storage structures # 19 to # 32 produced by the above-described method, the hydrogen storage amount, volume storage density, and 90% hydrogen storage time at 25 ° C. were determined. The results obtained are shown in Table 4.

  Table 4 shows that hydrogen storage is possible at 25 degreeC. Furthermore, the following can be understood.

(1) From the results of the hydrogen storage structures # 19 and # 20, it can be seen that the 90% hydrogen storage time can be shortened by increasing the number of hydrogen storage layers.

(2) From the results of the hydrogen storage structures # 21 to # 23, it is understood that the hydrogen storage amount and the 90% hydrogen storage time are improved as the number of the hydrogen storage layers and the hydrogen diffusion layers is increased.

(3) From the results of hydrogen storage structures # 24 to 28, when increasing the number of hydrogen storage layers and hydrogen diffusion layers, 90% hydrogen storage time is shortened by reducing the thickness of the hydrogen storage layer. You can see that

(4) From the results of hydrogen storage structures # 29 to 32, when increasing the number of hydrogen storage layers and hydrogen diffusion layers, 90% hydrogen storage time is shortened by increasing the thickness of the hydrogen diffusion layer. You can see that
(5) From the results of the hydrogen storage structures # 24 to 32, when increasing the number of layers of the hydrogen storage layer and the hydrogen diffusion layer, 90% hydrogen storage time was excellent by setting A / B to 1-15. It can be seen that a hydrogen storage structure can be obtained.

  In the hydrogen storage structures # 33 to # 35 manufactured by the above-described method, the hydrogen diffusion layer having a thickness of 60 nm was in contact with the hydrogen dissociation layer. Further, FIG. 5 shows a transmission electron micrograph of the cross section of the hydrogen storage structure # 35.

  Using the hydrogen storage structures # 33 to # 35, the temperature dependence of the hydrogen release amount was examined. The obtained result is shown in FIG. It can be seen from FIG. 6 that hydrogen release from below 100 ° C. can be realized by using Ni as the hydrogen diffusion material.

It is a perspective view showing the hydrogen storage structure of the present invention concerning a first embodiment. It is a perspective view showing the hydrogen storage structure of the present invention concerning a second embodiment. It is a perspective view showing the hydrogen storage structure of the present invention concerning a third embodiment. It is a schematic block diagram of a PCT apparatus. It is a transmission electron micrograph of the cross section of hydrogen storage structure # 35. FIG. 6 is a diagram showing the temperature dependence of the hydrogen release amount of the hydrogen storage structures # 33 to # 35.

Explanation of symbols

1 Hydrogen storage layer 2 Hydrogen diffusion layer 3 Hydrogen separation layer

Claims (7)

  A hydrogen storage structure comprising: a hydrogen storage layer including Mg or an Mg-based hydrogen storage alloy; and a pair of hydrogen diffusion layers provided so as to sandwich the hydrogen storage layer and including a hydrogen diffusion material. A hydrogen storage structure comprising a plurality of hydrogen storage layers containing Mg or a Mg-based hydrogen storage alloy and hydrogen diffusion layers containing a hydrogen diffusion material alternately.   The hydrogen storage structure according to claim 1 or 2, wherein a hydrogen equilibrium pressure at 25 ° C of the hydrogen diffusing material is 0.1 MPa or more and higher than a hydrogen equilibrium pressure at 25 ° C of Mg or the Mg-based hydrogen storage alloy. body.   4. The hydrogen storage structure according to claim 1, wherein the hydrogen diffusing material is at least one selected from TiMn, TiCr, TiFe, Ti, and V. 5.   The hydrogen diffusion material is stable against hydrogen, and the hydrogen diffusion coefficient of the hydrogen diffusion material at 25 ° C is higher than the hydrogen diffusion coefficient of Mg or the Mg-based hydrogen storage alloy at 25 ° C. 3. The hydrogen storage structure according to 2.   The hydrogen storage structure according to claim 1, wherein the hydrogen diffusion material is Ni. The hydrogen storage structure according to any one of claims 1 to 6, further comprising a hydrogen dissociation layer containing a hydrogen dissociation material as an outermost layer.

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