Single-phase AB3 type superlattice hydrogen storage alloy and method for manufacturing the same

Abstract

This invention belongs to the field of hydrogen storage alloys, and specifically discloses a single-phase AB3 type superlattice hydrogen storage alloy and a method for producing the same. [Solution] The hydrogen storage alloy of the present invention has a single-phase AB3 type crystalline phase structure, and other multi-phase or single-phase A2B7, A5B 19 Compared to hydrogen storage alloys, it has higher hydrogen storage capacity and cycle stability, with a hydrogen storage capacity of 1.8 wt.% or more, an effective hydrogen release of 1.7 wt.% or more, and a capacity retention rate of 95% or more after 200 cycles.

Description

[Technical Field]

[0001] This invention belongs to the field of hydrogen storage alloys, and more specifically, relates to a single-phase AB3 type superlattice hydrogen storage alloy and a method for producing the same. [Background technology]

[0002] According to domestic and international research reports, rare earth hydrogen storage materials are A m B n It is named as follows: Here, A is an element with a strong affinity for hydrogen and can react with hydrogen to produce hydrides, mainly rare earth elements such as Ti, Mg, Zr, and V. B is a control element for hydrogen gas transfer and release, mainly transition metals such as Ni, Co, and Cr. Element B generally does not react with hydrogen, but after forming an alloy with A, it can catalyze hydrogen absorption and release. Commonly seen rare earth hydrogen storage materials are AB5 type and superlattice type (e.g., AB3, A2B3, A5B) 19 Includes AB4 and other rare earth modifiers.

[0003] AB5-type hydrogen storage alloy materials (e.g., LaNi5) have advantages such as being easily activated and having good cycle stability, but their low gravimetric hydrogen storage density (approximately 1.4 wt%) limits their use in gas-solid hydrogen storage (hydrogen energy and fuel cells, etc.). To increase gravimetric hydrogen storage density, novel rare-earth hydrogen storage materials with superlattice structures have become a hot topic in recent research. The crystal structure of rare-earth superlattice hydrogen storage materials is formed by the stacking of [A2B4] and [AB5] subunits along the c-axis, so these hydrogen storage materials combine the high capacity characteristics of AB2-type alloys with the easily activated advantages of AB5-type alloys. The Osaka National Laboratory in Japan has developed a high-performance PuNi3-type superlattice hydrogen storage material (AB3-type) using powder metallurgy technology and lightweight element substitution methods, achieving a reversible hydrogen storage and release density of over 1.8 wt% at room temperature, which is significantly higher than conventional AB5-type hydrogen storage materials. Many researchers in China have also studied superlattice hydrogen storage materials for gas-solid hydrogen storage. The hydrogen storage density of the obtained materials at room temperature exceeded 1.7 wt%, but the hydrogen release density at room temperature was only 1.4-1.6 wt%. In addition to hydrogen storage capacity, the cycle life of rare-earth hydrogen storage materials is also extremely important. Ibaraki University in Japan discovered that by forming a Pr1-xMgxNi3 alloy with Mg instead of Pr, the volume of the unit cell can be anisotropically contracted, allowing for reversible adsorption and desorption of hydrogen and preventing changes in the alloy structure. Yanshan University has proposed that asynchronous expansion and contraction between the [A2B4] and [AB5] sublattices generates stress in the alloy superlayer structure, damaging cycle stability. Shanghai University discovered that substituting a small amount of Y with Mg significantly suppresses amorphization by hydrogen in the La-Y-Ni system, increasing electrochemical capacity and improving cycle capacity retention by a factor of 1. Therefore, by adding Mg, it is expected that the development of new rare-earth hydrogen storage materials with high hydrogen storage density and long lifetimes will be achieved by adjusting the superlattice subunits, substituting lightweight elements, and adjusting the size of the unit cell and the fit between subunits.

[0004] However, the Mg element is light in mass and low in melting point. During the process of manufacturing the hydrogen storage alloy, the melting temperature or heat treatment temperature generally exceeds the melting point of the Mg element. Therefore, it is easy to float, volatilize, or adhere to the device, resulting in a non-uniform distribution of the Mg element in the hydrogen storage alloy, making it impossible to control the content of the Mg element. Moreover, the manufactured hydrogen storage alloy generally has multiple alloy phase structures, reducing the weight hydrogen storage density and lifespan of the hydrogen storage alloy. Therefore, currently, the process of adjusting and controlling the crystal phase structure and state of the hydrogen storage alloy with Mg is still immature, and it is impossible to effectively obtain a single-phase hydrogen storage alloy through a simple process to achieve the purpose of improving the weight hydrogen storage density and lifespan of the hydrogen storage alloy.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Regarding the problem that the process of adjusting and controlling the crystal phase structure and state of the hydrogen storage alloy with Mg according to the above prior art is difficult to manufacture a single-phase hydrogen storage alloy, the present invention provides a single-phase AB3-type superlattice hydrogen storage alloy and a manufacturing method thereof.

Means for Solving the Problems

[0006] Specifically, to achieve the above object, the following technical solutions are included.

[0007] A hydrogen storage alloy of chemical general formula Y 1-x-y A x Mg y Ni 3-z B z wherein x, y, and z are stoichiometric ratios, and the values of x, y, and z satisfy the formula 0 ≦ x ≦ 0.2, 0.1 < y ≦ 0.2, 0 ≦ z ≦ 0.2. A contains at least one element of Sm, La, and Ca, B contains at least one element of Co, Cr, Zn, and Mo, and the hydrogen storage alloy has a single-phase AB3-type crystal phase structure. Hydrogen storage alloy.

[0008] The hydrogen storage alloy of the present invention has a single-phase AB3-type superlattice crystal phase structure, and other multiphase or single-phase A2B7, A5B 19 Compared with hydrogen storage alloys, it has a higher hydrogen storage capacity and cycle stability.

[0009] Preferably, the hydrogen storage alloy is Y 0.7 Sm 0.15 Mg 0.15 Ni 2.9 Co 0.1 、Y 0.85 Mg 0.15 Ni3、Y 0.8 La 0.05 Mg 0.15 contains at least one of the chemical general formulas Y

[0010] Preferably, the hydrogen storage alloy has a (Y,Mg)1Ni3 crystal phase.

[0011] (1) According to the stoichiometric ratio of the chemical general formula Y 1-x-y A x Mg y Ni 3-z B z mixing the simple substances of each element as raw materials; (2) dissolving the simple substance raw materials of each element other than the Mg simple substance raw material; (3) further adding the Mg simple substance raw material and dissolving it to obtain an alloy melt; (4) strip casting the alloy melt to obtain an alloy strip; (5) heat-treating the alloy strip to obtain the hydrogen storage alloy. A method for producing a hydrogen storage alloy.

[0012] In the method of the present invention, first, the Mg simple substance raw material and other metal element simple substance raw materials are dissolved separately, then the alloy melt is formed by strip casting, and finally the alloy strip is heat-treated. Each process cooperates with each other to accurately control the content of the Mg element, optimize the alloy phase structure, and achieve the purpose of improving the alloy performance.

[0013] The method of the present invention overcomes the drawbacks of the non-uniform distribution of Mg elements, the difficulty in controlling the Mg content, and the presence of multiple crystalline phases in the alloy, and makes it possible to obtain a single-phase AB3 type hydrogen storage alloy, which has a high hydrogen storage density and a long hydrogen storage lifetime.

[0014] Preferably, in step (1), when the above-mentioned compounding is performed, the general chemical formula Y 1-x-y A x Mg y Ni 3-z B z Depending on the mass of the Mg element, the Mg content will be in excess by 15-30 wt.%.

[0015] This invention increases the Mg content in the alloy by adding excess Mg, allowing for more precise control of the Mg content, improving lattice stability, and further enhancing the hydrogen storage performance of the hydrogen storage alloy.

[0016] Preferably, in step (2), induction dissolution is employed, the power for induction dissolution is 15-20 kW, and the duration of induction dissolution is 20-30 min.

[0017] Preferably, in step (3), induction dissolution is employed, the power for induction dissolution is 10 to 15 kW, and the duration of induction dissolution is 4 to 8 min.

[0018] Preferably, in step (4), the speed of the strip cast is 0.5 to 1.5 m / s.

[0019] Preferably, in step (5), the heat treatment temperature is 900 to 950°C, the heat treatment time is 2 to 6 hours, and the heating rate when raising the temperature to the heat treatment temperature is 5 to 10°C / min. [Effects of the Invention]

[0020] Compared to the prior art, the present invention offers the following beneficial effects. The hydrogen storage alloy of the present invention has a single-phase AB3 type superlattice crystal phase structure, and has a high hydrogen storage density and a long hydrogen storage lifetime, where the hydrogen storage capacity reaches 1.8 wt.% or more, the effective hydrogen release reaches 1.7 wt.% or more, and the capacity retention rate after 200 cycles reaches 95% or more. [Brief explanation of the drawing]

[0021] [Figure 1] This is an SEM image of the hydrogen storage alloy of Example 1. [Figure 2] This is an SEM image of the hydrogen storage alloy of Comparative Example 1. [Figure 3] This is an SEM image of the hydrogen storage alloy of Comparative Example 3. [Figure 4] This is an SEM image of the hydrogen storage alloy of Comparative Example 4. [Modes for carrying out the invention]

[0022] To better illustrate the object, technical proposal, and advantages of the present invention, the present invention will be further described below with reference to specific examples. Unless otherwise specified, the test methods used in the examples and / or comparative examples are all conventional methods, and unless otherwise specified, the materials, reagents, etc. used are all commercially available.

[0023] Example 1 The method for manufacturing hydrogen storage alloys includes the following steps:

[0024] (1) In molar ratio, chemical formula Y 0.7 Sm 0.15 Mg 0.15 Ni 2.9 Co 0.1 Accordingly, each metal element was blended as a raw material, with a total mass of 3 kg for each elemental raw material. Based on the mass of Mg element calculated using the above chemical formula, an excess of 20 wt.% was added. That is, if the mass of Mg element calculated using the above chemical formula is represented by m1, and the mass of the elemental Mg raw material is represented by m, then m = m1 + m1 × 20%.

[0025] (2) In a 5 kg class strip cast induction melting furnace, elemental raw materials of Y, Sm, Ni, and Co, other than elemental Mg, were melted, with a melting power of 18 kW and a melting time of 20 min.

[0026] (3) Furthermore, the elemental Mg raw material was added and dissolved, with a dissolution power of 12 kW and a dissolution time of 5 min, to obtain a uniform molten alloy.

[0027] (4) The molten alloy was strip-cast at a strip-casting speed of 1.5 m / s to obtain the alloy strip.

[0028] (5) The alloy strip was heated from room temperature to 950°C at a heating rate of 5°C / min, held at room temperature for 5 hours, and then cooled in the furnace to room temperature to obtain the hydrogen storage alloy.

[0029] Example 2 The method for manufacturing hydrogen storage alloys includes the following steps:

[0030] (1) In molar ratio, chemical formula Y 0.85 Mg 0.15 Following Ni3, each element was blended as a raw material, with a total mass of 3 kg of each elemental raw material. Based on the mass of Mg element calculated using the above chemical formula, an excess of 20 wt.% was added. That is, if the mass of Mg element calculated using the above chemical formula is represented by m1, and the mass of the elemental Mg raw material is represented by m, then m = m1 + m1 × 20%.

[0031] (2) In a 5 kg class strip cast induction melting furnace, elemental Y and Ni raw materials other than elemental Mg were melted, with a melting power of 20 kW and a melting time of 30 min.

[0032] (3) Furthermore, the elemental Mg raw material was added and dissolved, with a dissolution power of 15 kW and a dissolution time of 5 min, to obtain a uniform molten alloy.

[0033] (4) The molten alloy was strip-cast at a strip-casting speed of 0.8 m / s to obtain the alloy strip.

[0034] (5) The alloy strip was heated from room temperature to 950°C at a heating rate of 5°C / min, held at room temperature for 4 hours, and then cooled in the furnace to room temperature to obtain the hydrogen storage alloy.

[0035] Example 3 The method for manufacturing hydrogen storage alloys includes the following steps:

[0036] (1) In molar ratio, chemical formula Y 0.8 La 0.05 Mg 0.15 Following Ni3, each element was blended as a raw material, with a total mass of 3 kg of each elemental raw material. Based on the mass of Mg element calculated using the above chemical formula, an excess of 20 wt.% was added. That is, if the mass of Mg element calculated using the above chemical formula is represented by m1, and the mass of the elemental Mg raw material is represented by m, then m = m1 + m1 × 20%.

[0037] (2) In a 5 kg class strip cast induction melting furnace, elemental raw materials of Y, La, and Ni, other than elemental Mg, were melted, with a melting power of 20 kW and a melting time of 20 min.

[0038] (3) Furthermore, the elemental Mg raw material was added and dissolved, with a dissolution power of 15 kW and a dissolution time of 3 min, to obtain a uniform molten alloy.

[0039] (4) The molten alloy was strip-cast at a strip-casting speed of 1.5 m / s to obtain the alloy strip.

[0040] (5) The alloy strip was heated from room temperature to 925°C at a heating rate of 5°C / min, held at room temperature for 3 hours, and then cooled in the furnace to room temperature to obtain the hydrogen storage alloy.

[0041] Example 4 The method for manufacturing hydrogen storage alloys includes the following steps:

[0042] (1) In molar ratio, chemical formula Y 0.7 Sm 0.15 Mg0.15 Ni 2.9 Co 0.1 Accordingly, each element was blended as a raw material, with the total mass of each elemental raw material being 3 kg. Based on the mass of Mg element converted using the above chemical formula, an excess of 20 wt.% was added. That is, if the mass of Mg element converted using the above chemical formula is represented by m1, and the mass of the elemental Mg raw material is represented by m, then m = m1 + m1 × 20%.

[0043] (2) In a 5 kg class strip cast induction melting furnace, elemental raw materials of Y, Sm, Ni, and Co, other than elemental Mg, were melted. The melting power was 19 kW and the melting time was 25 min.

[0044] (3) Furthermore, the elemental Mg raw material was added and dissolved, with a dissolution power of 12 kW and a dissolution time of 4 min, to obtain a uniform molten alloy.

[0045] (4) The molten alloy was strip-cast at a strip-casting speed of 1 m / s to obtain the alloy strip.

[0046] (5) The alloy strip was heated from room temperature to 950°C at a heating rate of 5°C / min, held at room temperature for 6 hours, and then cooled in the furnace to room temperature to obtain the hydrogen storage alloy.

[0047] Comparative Example 1 The difference between this comparative example and Example 1 is that in this comparative example, the molding was not carried out using the strip casting method, but rather by the ingot casting method, and this method includes the following steps.

[0048] (1) In molar ratio, chemical formula Y 0.7 Sm 0.15 Mg 0.15 Ni 2.9 Co 0.1 Accordingly, each element was blended as a raw material, with the total mass of each elemental raw material being 3 kg. Based on the mass of Mg element converted using the above chemical formula, an excess of 20 wt.% was added. That is, if the mass of Mg element converted using the above chemical formula is represented by m1, and the mass of the elemental Mg raw material is represented by m, then m = m1 + m1 × 20%.

[0049] (2) In a 5 kg class strip cast induction melting furnace, elemental raw materials of Y, Sm, Ni, and Co, other than elemental Mg, were melted, with a melting power of 18 kW and a melting time of 20 min.

[0050] (3) Furthermore, the elemental Mg raw material was added and dissolved, with a dissolution power of 12 kW and a dissolution time of 5 min, to obtain a uniform molten alloy.

[0051] (4) The molten alloy was cast, and after casting, it was allowed to cool naturally to obtain an ingot.

[0052] (5) The ingot was heated from room temperature to 950°C at a heating rate of 5°C / min, held at room temperature for 5 hours, and then cooled in the furnace to room temperature to obtain a hydrogen storage alloy.

[0053] Comparative Example 2 The difference between this comparative example and Example 1 is that the alloy strip was not heat-treated in this comparative example, and it includes the following steps.

[0054] (1) In molar ratio, chemical formula Y 0.7 Sm 0.15 Mg 0.15 Ni 2.9 Co 0.1 Accordingly, each element was blended as a raw material, with the total mass of each elemental raw material being 3 kg. Based on the mass of Mg element converted using the above chemical formula, an excess of 20 wt.% was added. That is, if the mass of Mg element converted using the above chemical formula is represented by m1, and the mass of the elemental Mg raw material is represented by m, then m = m1 + m1 × 20%.

[0055] (2) In a 5 kg class strip cast induction melting furnace, elemental raw materials of Y, Sm, Ni, and Co, other than elemental Mg, were melted, with a melting power of 18 kW and a melting time of 20 min.

[0056] (3) Furthermore, the elemental Mg raw material was added and dissolved, with a dissolution power of 12 kW and a dissolution time of 5 min, to obtain a uniform molten alloy.

[0057] (4) The molten alloy was strip-cast at a strip-casting speed of 1.5 m / s to obtain the hydrogen storage alloy.

[0058] Comparative Example 3 The difference between this comparative example and Example 1 is that in this comparative example, the elemental Mg raw material and the elemental raw materials of other elements were not added separately, and the procedure included the following steps.

[0059] (1) In molar ratio, chemical formula Y 0.7 Sm 0.15 Mg 0.15 Ni 2.9 Co 0.1 Accordingly, each element was blended as a raw material, with the total mass of each elemental raw material being 3 kg. Based on the mass of Mg element converted using the above chemical formula, an excess of 20 wt.% was added. That is, if the mass of Mg element converted using the above chemical formula is represented by m1, and the mass of the elemental Mg raw material is represented by m, then m = m1 + m1 × 20%.

[0060] (2) In a 5 kg class strip casting induction melting furnace, elemental raw materials of Mg, Y, Sm, Ni, and Co were melted with a melting power of 18 kW and a melting time of 20 mins to obtain molten alloy.

[0061] (3) The molten alloy was strip-cast at a strip-casting speed of 1.5 m / s to obtain the alloy strip.

[0062] (4) The alloy strip was heated from room temperature to 950°C at a heating rate of 5°C / min, held at room temperature for 5 hours, and then cooled in the furnace to room temperature to obtain the hydrogen storage alloy.

[0063] Comparative Example 4 The difference between this comparative example and Example 1 is that the alloy component of this comparative example is Y 0.8 La 0.05 Mg 0.15 The result was Ni2, and the following steps were taken.

[0064] (1) In molar ratio, chemical formula Y 0.8 La 0.05 Mg0.15 Following Ni2, each element was blended as a raw material, with a total mass of 3 kg for each element. Based on the mass of Mg calculated using the above chemical formula, an excess of 20 wt.% was added. That is, if the mass of Mg calculated using the above chemical formula is represented by m1, and the mass of the elemental Mg raw material is represented by m, then m = m1 + m1 × 20%.

[0065] (2) In a 5 kg class strip cast induction melting furnace, elemental raw materials of Y, La, and Ni, other than elemental Mg, were melted, with a melting power of 18 kW and a melting time of 20 min.

[0066] (3) Furthermore, the elemental Mg raw material was added and dissolved, with a dissolution power of 12 kW and a dissolution time of 5 min, to obtain a uniform molten alloy.

[0067] (4) The molten alloy was strip-cast at a strip-casting speed of 1.5 m / s to obtain the alloy strip.

[0068] (5) The alloy strip was heated from room temperature to 950°C at a heating rate of 5°C / min, held at room temperature for 5 hours, and then cooled in the furnace to room temperature to obtain the hydrogen storage alloy.

[0069] Performance tests were conducted on the alloys produced in the above examples and comparative examples, and the specific test methods are as follows.

[0070] (1) Phase structure and phase content (wt.%): The phases of the alloy sample were identified using XRD, and the lattice constants were obtained by truing the XRD data using GSAS.

[0071] (2) Hydrogen storage capacity and effective hydrogen release (wt.%): After activating the alloy samples, PCT curve tests were performed at 25°C and a hydrogen gas pressure of 8 MPa to obtain the hydrogen storage capacity and the effective hydrogen release of 0.1 MPa or more.

[0072] (3) Capacity retention rate after 200 cycles (%): Hydrogen storage was performed for 30 minutes at 25°C and a hydrogen gas pressure of 8 MPa, followed by vacuuming at 25°C for 30 minutes. The hydrogen storage capacity retention rate of the alloy was tested as one cycle.

[0073] (3) Fine appearance of the alloy: Scanning electron microscope (SEM).

[0074] The test results are shown in Table 1 and Figures 1-4.

[0075] [Table 1]

[0076] From the above examples, Figure 1, and Table 1, it was found that the hydrogen storage alloys of the present invention are all single-phase AB3 type, i.e., (Y,Mg)1Ni3 crystalline phase, with a hydrogen storage capacity of 1.8 wt.% or more, an effective hydrogen release capacity of 1.7 wt.% or more, and a cycle capacity retention rate of 95% or more after 200 cycles, indicating high hydrogen storage density and long cycle life.

[0077] In the Examples and Comparative Example 1, in conjunction with Figure 2 and Table 1, it was found that after normal casting cooling was performed on the hydrogen storage alloy in Comparative Example 1, Mg had a low melting point, differed significantly from other components, and had a non-uniform distribution in the alloy. As a result, the AB5 phase appeared in the alloy, reducing the amount of hydrogen absorbed and released by the alloy. Furthermore, the presence of multiple phases in the alloy led to severe pulverization of hydrogen absorbed and released, making the superlattice structure prone to collapse and reducing the cycle performance.

[0078] In Example 1 and Comparative Example 2, as shown in Table 1, heat treatment of the alloy strip stabilized the phase structure in the alloy, improved the uniformity of the alloy, and reduced the lattice stress of the alloy. In Comparative Example 2, the alloy strip was not heat-treated, resulting in a multiphase structure, a large plateau slope factor in the PCT curve, and a decrease in hydrogen storage and release.

[0079] In Example 1 and Comparative Example 3, as shown in Figure 3 and Table 1, it was found that when the Mg raw material in Comparative Example 3 was used directly with other elements, Mg volatilization was severe, the Mg content in the alloy was insufficient, reproducibility was poor, superlattice structure formation was difficult, and hydrogen storage capacity decreased.

[0080] In Example 1 and Comparative Example 4, as shown in Figure 4 and Table 1, it was found that the alloy in Comparative Example 4 formed a multiphase structure, resulting in a decrease in hydrogen storage and release capacity. This indicates that different alloy components significantly influence the composition of the alloy's crystalline phase.

[0081] Finally, the above embodiments are merely for illustrating the technical concept of the present invention and do not limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical concept of the present invention without departing from the substance and scope of the technical concept.

Claims

1. Chemical general formula Y １－ｘ－ｙ A ｘ Mg ｙ Ni ３－ｚ B ｚ It is a hydrogen storage alloy, x, y, and z are stoichiometric ratios, and the values ​​of x, y, and z satisfy the equations 0 ≤ x ≤ 0.2, 0.1 < y ≤ 0.2, and 0 ≤ z ≤ 0.2, A contains at least one element from Sm, La, and Ca, B contains at least one element from Co, Cr, Zn, and Mo, and the hydrogen storage alloy is a single-phase AB ３ The crystalline phase structure is of type (Y, Mg) １ Ni ３ The hydrogen storage alloy has a crystalline phase, its hydrogen storage capacity reaches 1.8 wt.% or more, and its effective hydrogen release capacity reaches 1.7 wt.% or more. A hydrogen storage alloy characterized by the following features.

2. The hydrogen storage alloy is Y ０．７ Sm ０．１５ Mg ０．１５ Ni ２．９ Co ０．１ 、Y ０．８５ Mg ０．１５ Ni ３ 、Y ０．８ La ０．０５ Mg ０．１５ Ni ３ and contains at least one of the following chemical general formulas: A hydrogen storage alloy characterized by the description in claim 1.

3. A method for producing a hydrogen storage alloy according to claim 1 or 2, (1) Chemical general formula Y １－ｘ－ｙ A ｘ Mg ｙ Ni ３－ｚ B ｚ The steps involve blending each element in its pure form as raw materials according to its stoichiometric ratio, (2) A step of dissolving each elemental raw material other than the elemental Mg raw material, (3) Furthermore, the process involves adding and dissolving a pure Mg raw material to obtain a molten alloy, (4) The step of strip casting the molten alloy to obtain an alloy strip, (5) The step of heat-treating the alloy strip to obtain the hydrogen storage alloy, A method for producing a hydrogen storage alloy characterized by the following:

4. In step (1), when the above mixture is added, the general chemical formula Y １－ｘ－ｙ A ｘ Mg ｙ Ni ３－ｚ B ｚ Depending on the mass of the element Mg, the Mg content will be in excess by 15-30 wt.%. A method for producing a hydrogen storage alloy according to feature 3.

5. In step (2), induction dissolution is employed, the power for induction dissolution is 15-20 kW, and the duration of induction dissolution is 20-30 min. A method for producing a hydrogen storage alloy according to feature 3.

6. In step (3), induction dissolution is employed, the power for induction dissolution is 10 to 15 kW, and the duration of induction dissolution is 4 to 8 min. A method for producing a hydrogen storage alloy according to feature 3.

7. In step (4), the speed of the strip cast is 0.5 to 1.5 m / s. A method for producing a hydrogen storage alloy according to feature 3.

8. In step (5), the heat treatment temperature is 900 to 950°C, the heat treatment time is 2 to 6 hours, and the heating rate when raising the temperature to the heat treatment temperature is 5 to 10°C / min. A method for producing a hydrogen storage alloy according to feature 3.

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