A dysprosium oxide catalyzed multi-component hydrogen storage alloy and a preparation method thereof

Abstract

This invention belongs to the technical field of solid-state hydrogen storage alloy materials, and specifically provides a multi-component hydrogen storage alloy catalyzed by dysprosium oxide, its preparation method, and its preparation technology. The hydrogen storage alloy composition is: Mg 50‑x V x Y 10‑y Sm y N i 5‑z‑m Al z Ti m +n wt.%Dy2O3, where x,y,z,m are atomic ratios, and 0

Description

Technical Field

[0001] This invention belongs to the field of solid-state hydrogen storage alloy materials technology, and in particular provides a multi-component hydrogen storage alloy catalyzed by dysprosium oxide, its preparation method and preparation technology. Background Technology

[0002] The content of this invention, which relates to the problems discovered through research in the background art, should not be regarded as prior art.

[0003] Metal hydrides are considered promising hydrogen storage materials due to their high energy density and safety. Among them, magnesium is the most attractive candidate for solid-state hydrogen storage media due to its high hydrogen storage capacity, excellent reversibility, and abundance in the Earth's crust. Rare earth elements have a significant promoting effect on the hydrogen storage kinetics of Mg-based alloys; both the refinement of their microstructure and the catalytic formation of hydrides significantly enhance their hydrogen storage kinetics. Studies have confirmed that LaMg... 12 The alloy exhibits a favorable lamellar morphology and relatively fast hydrogen absorption kinetics. The reversible hydrogen storage capacity of the Mg3Y alloy is approximately 4.0 wt%.

[0004] During the research process of this invention, it was discovered that the hydrogen absorption kinetics of the Mg-Y binary alloy were improved. Compared with industrial MgH2, Mg... 24 Y5 alloy exhibits faster dehydrogenation rates. The improvement in hydrogen adsorption or desorption kinetics due to the addition of Y is mainly attributed to the catalytic effect and microstructure alteration of the ultrafine hydrogenated Y particles. The results indicate that Mg... 24 The Y5 alloy has better overall hydrogen storage performance than other Mg-Y binary alloys; however, it does not significantly improve the rate of hydrogen absorption or release. Summary of the Invention

[0005] The main objective of this invention is to provide a dysprosium oxide-catalyzed multi-component hydrogen storage alloy and its preparation method. This invention significantly improves the hydrogen storage performance of the alloy, substantially increasing the rate of hydrogen absorption or release, thereby providing a Mg alloy with high hydrogen storage capacity and good kinetic properties. 24 Y5 type hydrogen storage alloy and its corresponding preparation process.

[0006] The inventors discovered that transition metals (TMs), such as Pd, Ni, Nb, Ti, Cu, Zr, and V, also significantly improve the dehydrogenation / hydrogenation kinetics of Mg-based hydrogen storage materials by lowering the activation energy. This beneficial effect can be attributed to TMs acting as catalysts to decompose H2 molecules into absorbable hydrogen atoms. The combined addition of rare earth elements and other TM elements can further enhance the hydrogen storage performance of Mg. For example, at room temperature, Mg3LaNi... 0.1The alloy can even absorb 2.7 wt% hydrogen within 180 seconds. The Mg2Cu / MgCu2 phase transformation and morphological changes induced by dehydrogenation can explain the enhanced storage kinetics of the ternary LaCuMg8 alloy. Mg-TM-Y alloys have also been widely reported, such as Mg-Zn-Y, Mg-In-Y, Mg-Y-Ti, Mg-Y-Fe, Mg-Y-Ni, and Mg-Cu-Ni-Y. Compared with pure Mg alloys, these alloys exhibit improved hydrogenation / dehydrogenation performance, mainly due to the modification and catalytic effect of rare earth elements and TM on the alloy's microstructure. Furthermore, the non-transition element Al can also promote the hydrogen storage performance of Mg-based alloys. Binary Mg-Al alloys are a good example of composites, undergoing different stages of transformation through hydrogen absorption and desorption reactions. Mg 75 Al 25 Intermetallic compounds exhibit high hydrogen storage capacity, approaching 5 wt%, but their hydrogen storage kinetics are too slow to be usable below 300 °C. In contrast, Mg-La-Al composites prepared by hydrogen plasma-metal reaction show faster hydrogenation kinetics and a lower hydrogen absorption activation energy of 23.1 kJ / mol. -1 .

[0007] We believe that the multiphase synergistic effect of the Mg-Y-TM metal system alloy can further reduce the hydrogen desorption temperature and accelerate hydrogenation kinetics. This invention reduces the stability of Mg-based hydrides and improves their hydrogen adsorption and desorption kinetics by adding multiple rare earth elements Sm and Y, as well as transition metal elements V, Ni, Al, and Ti. Adding a small amount of catalyst Dy2O3 and subjecting the alloy to mechanical ball milling for an appropriate time yields a nanocrystalline microstructure, significantly improving the hydrogen storage performance of the target alloy. On the one hand, the addition of metal elements V, Ni, Al, and Ti promotes hydrogen dissociation and reduces the bonding strength of Mg-H bonds; on the other hand, the catalyst not only improves ball milling efficiency but also promotes the introduction of high-density crystal defects and improves the surface activity of the ball-milled particles.

[0008] The first aspect of this invention provides a multi-component hydrogen storage alloy catalyzed by dysprosium oxide, characterized in that the alloy contains multiple rare earth elements Sm and Y, as well as metallic elements V, Ni, Al, and Ti, and adds a catalyst Dy2O3, the composition of which is: Mg 50-x V x Y 10- y Sm y Ni 5-z-m Al z Ti m+n wt.% Dy2O3, where x, y, z, and m are atomic ratios, and 0 < x ≤ 5, 0 < y ≤ 3, 0 < z ≤ 2, 0 < m ≤ 2, n is the percentage of Dy2O3 in the alloy, and 4 ≤ n ≤ 12. The preferred atomic ratio is x:y:z:m = 1:2:1:0.5, and n = 7.

[0009] Another aspect of the present invention provides a method for preparing the above alloy. The preparation steps include: 1. Batching: According to the chemical formula composition Mg 50-x V x Y 10-y Sm y Ni 5-z-m Al z Ti m perform batching, where 0 < x ≤ 5, 0 < y ≤ 3, 0 < z ≤ 2, 0 < m ≤ 2. Among them, when proportioning Mg in the chemical formula composition, an 8% loss on ignition is added, and when proportioning rare earths Sm and Y, a 5% loss on ignition is added. The metal purity of the raw materials ≥ 99.5%.

[0010] 2. Alloy melting and rapid quenching: The weighed raw materials are melted by conventional heating methods, such as arc melting, induction heating melting or other heating methods. The heating conditions are: evacuate to 1×10 -2 -5×10 -5 Pa, and introduce a high-purity helium gas of 0.01 - 0.1 MPa or a helium + argon mixed gas with a volume ratio of about 1:1 as the protective gas. The heating temperature is 1750 - 1800 °C to obtain molten Mg 50-x V x Y 10-y Sm y Ni 5-z-m Al z Ti m liquid master alloy. After the molten alloy is kept in the protective gas atmosphere for about 5 minutes, the liquid master alloy is directly injected into a tundish with an NB nozzle embedded at the bottom. The liquid alloy continuously falls from the nozzle slit (nozzle slit width 0.3 mm) of the NB nozzle at the bottom of the tundish onto the surface of a water-cooled copper roller rotating at a linear speed of 5 - 30 m / s, obtaining a rapidly quenched alloy thin sheet with a thickness between 100 - 400 μm and a grain size between 10 - 100 nm. It is necessary to determine an appropriate rapid quenching cooling rate to ensure that the rapidly quenched alloy strip has an almost completely nanocrystalline structure.

[0011] 3. Mechanical ball milling: The rapidly quenched Mg 50-x V x Y 10-y Sm y Ni 5-z-m Al z Ti mThe alloy strip is mechanically crushed and passed through a 200-mesh sieve. The sieved alloy powder, along with a certain amount of catalyst Dy2O3 and stainless steel grinding balls, is loaded into a stainless steel ball mill jar. After vacuuming, high-purity argon gas is introduced, and the mixture is ball-milled in an all-around planetary high-energy ball mill for 3-8 hours, preferably 5 hours, with a ball-to-material ratio of 20:1 and a rotation speed of 350 rpm. During the ball milling process, the mill is stopped for 0.5 hours every hour of continuous operation to prevent the temperature of the grinding jar and abrasive from becoming too high. Determining the ball milling time is crucial. Excessive ball milling time will result in a large amount of amorphous phase, reducing the hydrogen storage capacity of the alloy. The optimal ball milling time ensures that there are no excessive amorphous phases in the ball-milled alloy and that the alloy powder is well dispersed without severe agglomeration, thus ensuring that the hydrogen absorption capacity of the alloy does not decrease significantly.

[0012] 4. Structural Analysis and Performance Testing: The phase structure of the as-cast and ball-milled powders was tested using XRD. The morphology and microstructure of the as-cast and ball-milled alloys were observed using high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The crystal state of the alloy was determined using selected area electron diffraction (SAED). The hydrogen absorption activation performance, hydrogen storage capacity, and hydrogen absorption / desorption kinetics of the alloy powders were tested using a semi-automatic Sieverts system. The hydrogen absorption temperature was 200℃, and the initial hydrogen pressure was 3 MPa; the hydrogen desorption temperature was 270℃, and the hydrogen desorption rate was 1 × 10⁻⁶ MPa. -4 The test was conducted at a pressure of MPa.

[0013] The beneficial effects of this invention are reflected in the following aspects:

[0014] In terms of alloy composition design, small amounts of multi-element rare earth elements Sm and Y are added, along with small amounts of metallic elements V, Ni, Al, and Ti for alloying. Mg and Y can form the main phase Mg of the alloy. 24 Y5, Sm can form Mg with Mg 41Various intermetallic compounds can be formed, including the Sm5 phase, the Mg2Ni phase formed by Mg and Ni, and the VAl3 phase formed by V and Al. Some of these intermetallic compounds are hydrogen-absorbing phases themselves, while others, although not hydrogen-absorbing, play a positive role in the hydrogen absorption and desorption of Mg-based alloys. Simultaneously, rare earth elements Y and Sm, along with metallic V and hydrogen, can form YH3, Sm3H7, and VH2 hydrides. These hydrides, dispersed as particles in the alloy matrix, act as nucleation sites for magnesium hydrides, significantly catalyzing the hydrogen absorption and desorption processes of Mg-based alloys. Rapid quenching yields a nanocrystalline structure, where grain boundaries provide excellent channels for hydrogen atom diffusion, which is particularly beneficial for improving the hydrogen absorption and desorption kinetics of Mg-based alloys. Furthermore, mechanically pulverizing rapidly quenched alloy sheets, adding a trace amount of catalyst Dy2O3, and then ball milling for a short time improves the surface state of the rapidly quenched alloy while maintaining its microstructure, further enhancing the thermodynamics and kinetics of hydrogen absorption and desorption. The hydrogen storage alloy powder prepared in this way not only possesses good hydrogen absorption and desorption capacity and excellent hydrogen absorption and desorption kinetics, but also shows great promise as a hydrogen supply carrier for hydrogen fuel cells. Furthermore, the alloy preparation process is simple and easy to operate, fully meeting the requirements for large-scale production. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0016] Figure 1 The SEM morphology of the as-cast alloys of Examples 1-6 is shown;

[0017] Figure 2 Photographs (a) and TEM images (b) of the rapidly quenched alloy strip of Example 1 are shown.

[0018] Figure 3 The SEM morphology of the ball-milled alloy particles of Examples 1-6 is shown;

[0019] Figure 4 The XRD diffraction patterns of the ball-milled powders from Examples 1-6 are shown.

[0020] Figure 5 The HRTEM morphology of the ball-milled alloys of Examples 1-6 is shown. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] The design concept and mechanism of the present invention will be further described in detail with reference to the accompanying drawings, comparative examples and embodiments, so as to make the technical solution of the present invention clearer.

[0023] This invention reveals that, in alloy composition design, element substitution can reduce the thermal stability of Mg-based alloy hydrides and improve their hydrogen absorption and desorption kinetics. In particular, the addition of rare earth elements Sm and Y significantly reduces the stability of magnesium hydrides because Sm and Y can form highly stable Sm3H7, YH2, and YH3 during hydrogen absorption. Mg and Ni can form the Mg2Ni phase, and V and Al can form the VAl3 phase; these intermetallic compounds also play a significant role in improving the hydrogen storage performance of Mg-based alloys.

[0024] In terms of preparation technology, melt quenching can yield precursors with ultrafine grains (nanoscale). Furthermore, the quenched structure contains a high density of crystal defects, including dislocations, stacking faults, twins, and numerous grain boundaries. This microstructure is highly beneficial for improving the thermodynamic and kinetic properties of the alloy. Unlike ball milling, the ultrafine structure and crystal defects obtained through quenching exhibit high stability. After multiple hydrogen absorption and desorption cycles, the grains are less prone to aggregation and growth. This results in excellent hydrogen absorption and desorption kinetics and good cycle stability.

[0025] Adding dysprosium oxide (Dy₂O₃) as a catalyst and ball milling for a short time improves the surface condition of the alloy while maintaining its microstructure in the rapidly quenched state, leveraging the advantages of both preparation processes. During ball milling, the catalyst is uniformly distributed within the alloy matrix, allowing it to fully exert its catalytic effect and thus improve the thermodynamics and kinetics of hydrogen absorption and desorption. The catalytic effect of Dy₂O₃ lies in its high hardness, which significantly cuts the alloy particles during ball milling, resulting in finer particles. The addition of a highly stable catalyst, after ball milling, ensures uniform distribution among the alloy particles, inevitably forming numerous active interfaces between the alloy and the catalyst. These interfaces provide excellent nucleation sites for hydride formation and decomposition. It is precisely this combination of rapid quenching, ball milling, and catalyst addition that significantly improves the thermodynamics and kinetics of hydrogen absorption and desorption in the alloy.

[0026] The present invention provides an example of RE-Mg-Ni-V-Al-Ti based Mg involved in the present invention through the following embodiments. 24 The composition and preparation method of Y5 type hydrogen storage alloy will be further explained.

[0027] The fuel cell of this invention uses RE-Mg-Ni-V-Al-Ti based Mg 24 Y5 type solid hydrogen storage alloy, its chemical formula is: Mg 50-x V x Y10-y Sm y Ni 5-z-m Al z Ti m + n wt.% Dy2O3, where x, y, z, m are atomic ratios, and 0 < x ≤ 5, 0 < y ≤ 3, 0 < z ≤ 2, 0 < m ≤ 2, n is the percentage of Dy2O3 in the alloy, and 4 ≤ n ≤ 12. The preferred atomic ratio x:y:z:m = 1:2:1:0.5, and n = 7.

[0028] The preparation method of the high-capacity RE-Mg-Ni-V-Al-Ti-based Mg 24 Y5-type hydrogen storage alloy includes the following steps:

[0029] A. Charge materials according to the chemical formula composition Mg 50-x V x Y 10-y Sm y Ni 5-z-m Al z Ti m Since the melting points of Mg, rare earth Sm and Y are relatively low and they are easy to volatilize, therefore, when formulating the ratio, 8% more Mg, 5% more rare earth Sm and Y are added to compensate for the loss by burning.

[0030] B. Place the prepared raw materials in a magnesia crucible in sequence. The massive rare earth Sm and Y are placed at the bottom of the crucible, metal V is placed on top of the rare earth Sm and Y, electrolytic Ni is placed on top of metal V, sponge Ti and metal Al are placed on top of metal Ni, and massive metal Mg is placed on the top. After the materials are placed in sequence, cover the furnace lid, evacuate to 1×10 -2 -5×10 -5 Pa, and fill with high-purity helium gas with a pressure of 0.01 - 0.1 MPa as the protective gas, and the melting temperature is 1750 - 1800 °C to obtain molten Mg 50-x V x Y 10-y Sm y Ni 5-z-m Al z Ti m Liquid master alloy.

[0031] C. Under an inert gas atmosphere, after the alloy melts and is held at that temperature for approximately 5 minutes, the liquid master alloy is directly injected into an intermediate ladle with an NB nozzle embedded at the bottom. The liquid alloy is continuously sprayed through the nozzle slits onto the smooth surface of a water-cooled copper roller rotating at 5-30 m / s, preferably 14 m / s, to obtain a rapidly quenched alloy sheet with a thickness between 100-400 μm. This rapidly quenched alloy has a columnar crystalline structure, which is a uniform nanocrystalline structure. The requirement for rapid quenching is to ensure that the rapidly quenched alloy strip has as many nanocrystalline structures as possible. If the rapid quenching cooling rate is too fast, a considerable proportion of amorphous phase will appear in the structure, which will significantly reduce the hydrogen absorption capacity of the alloy. If the cooling rate is too slow, a large number of microcrystalline structures will appear, weakening the hydrogen absorption and desorption kinetics of the alloy.

[0032] D. Rapidly quenched Mg 50-x V x Y 10-y Sm y Ni 5-z-m Al z Ti m After mechanical crushing and sieving through a 200-mesh sieve, the alloy strip is mixed with a certain amount of catalyst Dy2O3 and stainless steel grinding balls and loaded into a stainless steel ball mill jar. After vacuuming, high-purity argon gas is introduced, and the mixture is ball-milled for 5 hours in an all-around planetary high-energy ball mill. The ball-to-material ratio is 20:1, and the rotation speed is 350 rpm. During the ball milling process, the mill is stopped for 0.5 hours every hour of continuous operation to prevent the temperature of the grinding jar and abrasive from becoming too high. Through the above preparation process, the multi-component RE-Mg-Ni-V-Al-Ti based Mg described in this patent is obtained. 24 Y5 type hydrogen storage material. It is important to note that the ball milling process must be appropriate. Excessive ball milling time will result in more amorphous phases in the microstructure, and agglomeration will occur due to cold welding between particles. All of these factors will reduce the hydrogen absorption and desorption performance of the alloy.

[0033] E. The structure of the ball-milled powder was tested by XRD. The morphology and microstructure of the alloy particles after ball milling were observed by high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM), and the crystal state of the alloy was determined by selected area electron diffraction (SAED). The gaseous hydrogen storage capacity and hydrogen absorption and desorption kinetics of the alloy powder were tested using a fully automated Sieverts system. The hydrogen absorption temperature was 200℃, the initial hydrogen absorption pressure was 3 MPa, and the hydrogen release was at 270℃ and 1×10⁻⁶ MPa. -4 The test was conducted at a pressure of MPa.

[0034] The chemical composition and proportions of specific embodiments of the present invention are selected as follows:

[0035] Example 1: Mg 49 V1Y8Sm2Ni 3.5 Al1Ti 0.5 +7wt.%Dy2O3

[0036] Example 2: Mg 45 V5Y8Sm2Ni 3.5 Al1Ti 0.5 +7wt.%Dy2O3

[0037] Example 3: Mg 49 V1Y7Sm3Ni 3.5 Al1Ti 0.5 +4wt.%Dy2O3

[0038] Example 4: Mg 49 V1Y8Sm2Ni 2.5 Al2Ti 0.5 +8wt.%Dy2O3

[0039] Example 5: Mg 49 V1Y8Sm2Ni2Al1Ti2+10wt.%Dy2O3

[0040] Example 6: Mg 49 V1Y8Sm2Ni 3.5 Al1Ti 0.5 +12wt.%Dy2O3

[0041] Comparative Example 1: Mg 24 Y5 (quick quenching + ball milling)

[0042] According to the chemical formulas of each embodiment, bulk metal Mg, rare earth metals Sm and Y, metal V, electrolytic Ni, sponge Ti, and electrolytic Al were selected. The metal purity requirement was ≥99.5%. After polishing to remove the surface oxide layer, the selected bulk metals were weighed according to the stoichiometric ratio. Specifically, the proportion of metal Mg was increased by 8%, and the proportions of rare earth Sm and Y were increased by 5% to compensate for losses during smelting. During the preparation process, technical parameters at each stage included: vacuum reaching 1×10⁻⁶ during induction heating. -2 -5×10 -4 The process involves filling the gas with high-purity helium or a helium-argon mixture at a volume ratio of 1:1 at a pressure of 0.01-0.1 MPa; the melting temperature is 1750-1800℃; and the surface linear velocity of the rapidly quenched water-cooled copper roller is 5-30 m / s. The rapidly quenched thin sheets are mechanically crushed and passed through a 200-mesh sieve. They are then mixed with the catalyst Dy2O3 and stainless steel grinding balls and loaded into a stainless steel ball mill jar. The mixture is ball-milled using an omnidirectional planetary ball mill for 3-8 hours, with a 0.5-hour stop after every hour of continuous operation. All process parameters can be appropriately selected within the above range to prepare the hydrogen storage alloy powder described in the patent. Therefore, although only one typical embodiment is given in this invention, this embodiment is applicable to preparation methods with different parameters.

[0043] Process parameters for Example 1: According to the chemical formula Mg 49 V1Y8Sm2Ni 3.5 Al1Ti 0.5 The following materials were selected: bulk Mg, rare earth elements Sm and Y, metallic V, sponge Ti, electrolytic Ni, and Al. These metals had a purity of 99.5% and were weighed according to stoichiometric ratios, with 5 kg of material per furnace. The proportions were: bulk Mg 2562.0 g, rare earth Y 1487.6 g, rare earth Sm 628.9 g, metallic V 101.5 g, electrolytic Ni 409.2 g, sponge Ti 47.7 g, and electrolytic Al 53.7 g. The weighed bulk metals were placed in the magnesium oxide crucible of the medium-frequency induction furnace according to the designed process. Bulk rare earth elements Sm and Y were placed at the bottom of the crucible, metallic V on top of Sm and Y, electrolytic Ni on top of metallic V, sponge Ti and metallic Al on top of metallic Ni, and bulk Mg on top. The furnace lid was then closed, and a vacuum was evacuated for approximately 30 minutes to a vacuum degree of 5 × 10⁻⁶. -2 Above Pa, high-purity helium protective gas is added until the pressure reaches 0.04 MPa. The power is adjusted to 5 kW, and the temperature is controlled at 650℃ to melt the Mg metal. Then, the power is adjusted to 25 kW, and the temperature is controlled at 1800℃ to melt the remaining metals. After the molten alloy is held in the protective gas atmosphere for 5 minutes, the liquid master alloy is directly injected into the tundish with NB nozzles embedded at the bottom. The liquid alloy is continuously sprayed from the gaps in the NB nozzles at the bottom of the tundish (nozzle gap width 0.3 mm) onto the surface of a water-cooled copper roller rotating at a linear speed of 14 m / s, obtaining a rapidly quenched alloy sheet with a thickness of 160 μm and an average grain size of approximately 42 nm. The rapidly quenched Mg... 49 V1Y8Sm2Ni 3.5 Al1Ti 0.5 Alloy flakes were mechanically crushed and passed through a 200-mesh sieve. 20 grams of the sieved alloy powder, 1.4 grams of Dy₂O₃ catalyst, and 400 grams of stainless steel grinding balls were weighed and mixed together, then placed into a 250 ml stainless steel ball mill jar. The jar was evacuated, filled with high-purity argon, and sealed. The mixture was then ball-milled for 5 hours in an omnidirectional planetary high-energy ball mill. The ball mill was stopped for 0.5 hours after every hour of continuous operation.

[0044] Figure 1 The SEM images of the as-cast alloys in Examples 1-6 show that the addition of multi-element rare earth elements and various metals resulted in the formation of multiple intermetallic compounds, among which Mg and Y formed Mg 24 Y5 is the main phase, and Sm reacts with Mg to form Mg. 41 In the Sm5 phase, Mg and Ni form Mg2Ni, and V and Al form VAl3 phase, among other intermetallic compounds.

[0045] Figure 2The image shows a photograph of the rapidly quenched alloy strip. The thickness of the strip is approximately 160 μm. HRTEM observation revealed that the rapidly quenched alloy strip has an almost entirely nanocrystalline structure with an average grain size of approximately 42 nm.

[0046] Figure 3 The SEM images of the ball-milled powders in Examples 1-6 show that the alloy particles were well dispersed after ball milling, and no obvious agglomeration was observed.

[0047] Figure 4 The XRD patterns of the ball-milled alloys in Examples 1-6 show that the ball-milled materials have nanocrystalline and amorphous structural features.

[0048] Figure 5 The HRTEM morphology of the ball-milled alloys in Examples 1-6 shows that the alloys have nanocrystalline and a very small amount of amorphous structure.

[0049] The hydrogen absorption and release capacity and kinetics of the alloy powder in gaseous state were tested using a fully automated Sieverts instrument. The results are shown in Table 1.

[0050] Table 1 Hydrogen absorption and desorption kinetics of alloy powders with different compositions

[0051]

[0052] C max —Saturated hydrogen absorption (wt.%) at an initial hydrogen pressure of 3 MPa and a temperature of 200 °C; —The amount of hydrogen absorbed (wt.%) within 5 minutes at an initial hydrogen pressure of 3 MPa and a temperature of 200°C. —At an initial pressure of 1×10 -4 Hydrogen release (wt.%) within 20 minutes at MPa and 270℃.

[0053] The above results demonstrate that the ball-milled alloy powder possesses high hydrogen absorption and desorption capacity and excellent kinetic properties. In particular, the alloy exhibits good hydrogen desorption performance at a relatively low temperature (270℃), and the preparation process is simple and easy to operate, making it highly suitable for large-scale preparation. Clearly, the hydrogen absorption and desorption capacity of the alloy of this invention fully meets the hydrogen capacity requirements of fuel cell hydrogen supply systems. Compared with similar alloys both domestically and internationally, the hydrogen absorption and desorption kinetics of the alloy of this invention are significantly improved, especially with a markedly lower hydrogen desorption temperature.

[0054] Although the preferred embodiments of the present invention have been described, it is obvious to those skilled in the art that other embodiments can be adopted, such as changing the content of components and the amount of catalyst added. Various modifications and variations can be made without departing from the design concept of the present invention, and all such variations are protected by the present invention.

Claims

1. A dysprosium oxide-catalyzed multi-component hydrogen storage alloy with a chemical formula composition of: Mg 50-x V x Y 10-y Sm y Ni 5-z-m Al z Ti m +n wt.% Dy2O3, where x, y, z, m are atomic ratios, and 0 < x ≤ 5, 0 < y ≤ 3, 0 < z ≤ 2, 0 < m ≤ 2, n is the mass percentage of dysprosium oxide in the alloy, and 4 ≤ n ≤ 12.

2. The alloy according to claim 1, characterized in that, The preferred atomic ratio of the chemical formula is: x: y: z:m = 1: 2: 1: 0.5, n = 7.

3. A method for preparing a multi-component hydrogen storage alloy catalyzed by dysprosium oxide, characterized in that, The method steps include: (1) According to the chemical formula Mg 50-x V x Y 10-y Sm y Ni 5-z-m Al z Ti m The ingredients are mixed, where x, y, z, and m are the atomic ratios, and 0 < x < y < z < m. <x≤5, 0<y≤3, 0<z≤2, 0<m≤2; (2) Add the weighed raw materials to the magnesium oxide crucible in sequence, and evacuate to a vacuum of 1 × 10⁻⁶. -2 Up to 5×10 -5 Pa, then fill with 0.01 to 0.1 MPa of high-purity helium or a 1:1 helium + argon protective gas mixture, and heat to 1750-1800℃ using induction heating to obtain molten Mg. 50-x V x Y 10-y Sm y Ni 5-z-m Al z Ti m Liquid alloy; (3) The liquid master alloy prepared in step (2) is directly injected into the intermediate tundish with BN nozzles embedded at the bottom. The liquid alloy is continuously sprayed onto the smooth surface of a copper roller rotating at a linear speed of 5-30 m / s through the slit of the BN nozzle at the bottom of the intermediate tundish to obtain a fast quenching alloy strip with a thickness between 100-400 μm. The fast quenching strip should have a nanocrystalline structure with a grain size of 10-100 nm. (4) Rapidly quenched Mg 50-x V x Y 10-y Sm y Ni 5-z-m Al z Ti m The alloy is mechanically crushed and passed through a 200-mesh sieve. The sieved alloy powder, dysprosium oxide catalyst, and stainless steel grinding balls are loaded into a stainless steel ball mill jar, vacuumed, and then filled with high-purity argon gas. The jar is then ball-milled in an all-around planetary high-energy ball mill. The mass percentage of dysprosium oxide in the alloy is n wt.%, where n is 4 to 12.

4. The preparation method according to claim 3, characterized in that, In step (1), the atomic ratio x: y: z: m = 1: 2:1: 0.5; n=7.

5. The preparation method according to claim 3, characterized in that, In step (4), the ball milling parameters are: ball milling for 3-8 hours, ball-to-material ratio of 20:1, rotation speed of 350 rpm, and ball milling for 0.5 hours after each hour of continuous operation.

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