Hydrogen storage alloy and preparation method thereof

Abstract

The invention discloses a hydrogen storage alloy and a preparation method thereof, relates to the technical field of metal functional materials, and solves the problems of high reaction temperature and low hydrogen absorption and dehydrogenation rate of a magnesium-based hydrogen storage material in the prior art. The prepared hydrogen storage alloy comprises the following alloy components in parts by mass: 5-15 parts of nickel, 2-8 parts of yttrium, 2-8 parts of ytterbium, 68.8-91 parts of magnesium and 0-0.2 part of impurities. A magnesium ingot, a magnesium-yttrium alloy and a magnesium-ytterbium alloy are melted, then magnesium-nickel alloy is added, stirring is conducted till the magnesium-nickel alloy is melted, standing is conducted, and casting is conducted to obtain a hydrogen storage magnesium alloy cast ingot; the method comprises the following steps: crushing a hydrogen storage magnesium alloy cast ingot, loading into a stainless steel ball milling tank for dry milling, and adding a solvent into the tank body for wet milling after the dry milling is finished; and drying to obtain the magnesium alloy flaky powder. According to the invention, multiphase cooperation, structure regulation and interface optimization of multiple elements are utilized, so that the hydrogen absorption and desorption performance of the hydrogen storage material is obviously enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of metallic functional materials, and in particular to a hydrogen storage alloy and a preparation method thereof. Background Art

[0002] As the clean energy with the greatest potential for development in the 21st century, hydrogen, with its zero-carbon emissions, high energy density (142MJ / kg), and renewable nature, has become a key driver of the global energy transition toward a low-carbon, sustainable structure. However, hydrogen storage technology, a core component of large-scale hydrogen energy application, currently faces technical bottlenecks in balancing high capacity with mild operating conditions, severely restricting the large-scale development of the hydrogen energy industry chain.

[0003] Among the many hydrogen storage methods, solid-state hydrogen storage has become the focus of current research and industrial layout due to its advantages such as high safety and high energy density. Among them, magnesium-based alloys are widely regarded as the solid-state hydrogen storage materials with the greatest industrial potential due to their excellent theoretical hydrogen storage capacity (MgH2 theoretical mass hydrogen storage density is 7.6wt.%), abundant resources (magnesium content in the earth's crust is 2.3%) and environmental friendliness. However, the practical application of magnesium-based hydrogen storage materials still faces technical bottlenecks such as high reaction temperature and slow hydrogen absorption and desorption rate, and urgently need to be broken through through material design and interface regulation.

[0004] At present, Mg-Ni alloys have a stable catalytic alloy phase (Mg2Ni) and its reversible hydrogen storage hydride (Mg2NiH4), which can significantly improve the hydrogen storage kinetics and thermodynamic properties. However, the Mg2Ni phase is usually coarse and unevenly distributed, which affects its catalytic effect. By doping the rare earth yttrium (Y) element in the Mg-Ni alloy, the Mg2Ni phase can be effectively refined and a long-period ordered stacking (LPSO) structure can be formed. During the hydrogen absorption process, the LPSO phase can be in situ decomposed into uniformly distributed MgH2, Mg2NiH4 and YH x Nanocomposite system, in which YH x The formation of MgH2 not only induces the generation of MgH2, but also introduces lattice distortion and defects, thereby providing more diffusion channels for H atoms. However, the high dehydrogenation enthalpy change of Mg-Ni-Y alloy (about 75kJ / mol H2) still restricts its efficient hydrogen desorption application under medium-temperature conditions (such as around 250°C). Therefore, how to further reduce its dehydrogenation thermodynamic barrier is a key issue in realizing the practical engineering application of magnesium-based alloy materials.

[0005] In this context, the introduction of the rare earth element ytterbium (Yb) has become a strategy that has attracted much attention. The incorporation of Yb can significantly improve the hydrogen storage performance of magnesium alloys, and its effects are mainly reflected in two aspects: kinetics and thermodynamics. On the one hand, it will inhibit the growth of grains or second phases through the pinning effect, thereby enhancing the kinetics of hydrogen absorption and desorption; on the other hand, in the process of forming the Mg2Yb phase, it will cause lattice distortion or disordered atomic arrangement at the interface, weakening the strength of the Mg-H bond, thereby reducing the decomposition enthalpy (ΔH) of MgH2, and significantly improving the hydrogen storage thermodynamic properties of magnesium alloys. In addition, Yb oxide (Yb2O3) is more easily reduced by hydrogen than MgO, which can reduce the obstruction of the passivation layer on the surface of the magnesium alloy to hydrogen penetration. For example, Chinese invention patent CN101120111A discloses a magnesium alloy for hydrogen storage. The patent document discloses that the introduction of refining elements such as Yb at a content of up to 2wt.% can optimize the hydrogen storage performance of magnesium-nickel alloys. However, the technical solution in this patent focuses primarily on trace Yb ​​doping and its kinetic optimization effects on grain refinement, without fully exploring the potential effects of Yb in regulating thermodynamic properties, phase interfaces, and reaction pathways. In particular, key scientific issues such as the phase transition behavior, interface structure evolution, and the behavior of hydrogen storage reaction intermediates brought about by further increasing the Yb doping level in the Mg-Ni-Y alloy system have not been systematically explored.

[0006] Therefore, a Mg-Ni-Y-Yb alloy was developed to achieve its structure-performance synergistic optimization, thereby effectively reducing the dehydrogenation thermodynamic barrier while maintaining excellent hydrogen absorption and dehydrogenation kinetics, and improving the hydrogen desorption efficiency of the material under medium-temperature conditions, providing new ideas and feasible paths for the engineering application of magnesium-based hydrogen storage materials. Summary of the Invention

[0007] In order to solve the problems of high reaction temperature and slow hydrogen absorption and desorption rates of magnesium-based hydrogen storage materials in the prior art, the present invention proposes a hydrogen storage alloy and a preparation method thereof. The technical solution of the present invention is as follows:

[0008] A hydrogen storage alloy,

[0009] Calculated by mass, it contains the following alloy components:

[0010] 5-15 parts of nickel, 2-8 parts of yttrium, 2-8 parts of ytterbium, 68.8-91 parts of magnesium, and 0-0.2 parts of impurities.

[0011] A method for preparing a hydrogen storage alloy comprises the following steps:

[0012] S1: weighing and mixing a magnesium ingot, a magnesium yttrium alloy, a magnesium ytterbium alloy, and a magnesium nickel alloy according to the alloy composition, placing the magnesium ingot, the magnesium yttrium alloy, and the magnesium ytterbium alloy into a melting crucible and heating and melting them; then adding the magnesium nickel alloy and stirring until the magnesium nickel alloy is melted, cleaning the surface of the melt, cooling the magnesium alloy melt and allowing it to stand before casting to obtain a hydrogen storage magnesium alloy ingot;

[0013] S2: crushing the hydrogen storage magnesium alloy ingot, and placing the hydrogen storage magnesium alloy particles into a stainless steel ball mill for dry grinding; after the dry grinding, adding a solvent into the tank for wet grinding to obtain a dispersion containing magnesium alloy powder, and placing the dispersion in a vacuum drying oven for drying to obtain a hydrogen storage alloy.

[0014] Furthermore, the protective atmosphere during the heating and melting in S1 is a mixture of SF6 and CO2, and the temperature of the heating and melting is 730-750°C.

[0015] Furthermore, the cooling in S1 is cooling to 680-700°C.

[0016] Furthermore, the size of the hydrogen storage magnesium alloy ingot crushed in S2 is less than 2 μm.

[0017] Furthermore, the rotation speed of the dry grinding in S2 is 350-450 rad / min, the dry grinding is performed every 30 minutes, each operation is 15 minutes, and the total dry grinding time is 10-20 hours.

[0018] Furthermore, the solvent in S2 is ethanol or acetone.

[0019] Furthermore, the rotation speed of the wet grinding in S2 is 350-450 rad / min, wherein the wet grinding is performed once every 20 minutes, each operation is 5 minutes, and the total wet grinding time is 1-3 hours.

[0020] Furthermore, the atmosphere for both the dry grinding and the wet grinding in S2 is an argon atmosphere.

[0021] Compared with the prior art, the present invention solves the problems of high reaction temperature and slow hydrogen absorption and desorption rates of magnesium-based hydrogen storage materials in the prior art, and has the following specific beneficial effects:

[0022] 1. Synergistic effect enhances hydrogen absorption and dehydrogenation performance: The present invention constructs a Mg-Ni-Y-Yb multi-element alloy structure, utilizes multi-phase synergy of multiple elements, structural regulation and interface optimization, achieves simultaneous improvement of hydrogen diffusion path and thermodynamic properties, and significantly enhances the hydrogen absorption and dehydrogenation performance of the hydrogen storage material. Among them, the Mg2Ni phase formed by Ni and Mg can generate a reversible hydrogen storage compound Mg2NiH4, whose hydrogen diffusion rate is significantly higher than that of MgH2 and has a lower formation enthalpy, which helps to reduce the hydrogen desorption temperature of the material; at the same time, the d orbital hybridization effect of Ni reduces the dissociation energy barrier of hydrogen molecules, which can effectively promote the rates of hydrogen absorption and dehydrogenation reactions; the introduction of Y element not only stores hydrogen itself to form YH2 / YH3, playing the role of "hydrogen pump", but also promotes the formation of LPSO structure in the alloy, increasing the number of phase boundaries and hydrogen diffusion channels; on this basis, the further introduction of Yb element can refine the LPSO structure, form Mg2Yb phase and induce lattice distortion, thereby weakening the Mg-H bond and reducing the dehydrogenation enthalpy. At the same time, Yb2O3 is easily reduced by hydrogen, effectively improving the hydrogenation efficiency and the reaction kinetics.

[0023] 2. Preparation Process Optimization: The present invention applies a composite mechanical ball milling process (dry grinding followed by wet grinding) to the alloy ingot. Dry grinding initially refines the particle size and introduces lattice defects and dislocations, enhancing the material's surface activity. Wet grinding further refines the particles to produce a hydrogen storage material with a flaky powder structure ≤10 μm thick. This flaky structure effectively increases the specific surface area of ​​the alloy powder, shortens the diffusion path of hydrogen atoms within the alloy during hydrogen absorption and dehydrogenation, and significantly enhances the alloy's hydrogen absorption and desorption kinetics. Furthermore, the Mg-Ni-Y-Yb alloy hydrogen storage material of the present invention exhibits a maximum hydrogen storage capacity of no less than 4.5 wt.% at 3 MPa and a dehydrogenation rate of no less than 45% at 250°C under vacuum for 5 minutes. This process significantly improves the material's microstructure, optimizes hydrogen diffusion channels, and improves reaction kinetics. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Scanning electron microscope images of the magnesium alloy ingots prepared in Comparative Example 1 and Example 1;

[0025] Figure 2 The scanning electron microscope images of the magnesium alloy powders prepared in Comparative Example 2 and Example 1;

[0026] Figure 3 The hydrogen absorption kinetic curves of Example 1 and Comparative Example 1 under the test condition of 250°C are shown;

[0027] Figure 4 The hydrogen absorption kinetic curves of Example 1 and Comparative Example 1 under the test condition of 340°C are shown;

[0028] Figure 5 Dehydrogenation kinetics curve of Example 1 and Comparative Example 1 at 250℃ under vacuum condition;

[0029] Figure 6 Dehydrogenation kinetics curve of Example 1 and Comparative Example 1 at 340℃ under vacuum condition;

[0030] Figure 7 Scanning electron microscope image of magnesium alloy ingot prepared for Example 2.

[0031] Figure 8 Scanning electron microscope image of magnesium alloy ingot prepared for Example 3. DETAILED DESCRIPTION

[0032] In order to make the technical solutions of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the specification of the present application. It should be noted that the following embodiments are only used to better understand the technical solutions of the present application, and should not be understood as a limitation of the present application.

[0033] Comparative Example 1.

[0034] S1: The magnesium ingot, magnesium-yttrium alloy and magnesium-nickel alloy were weighed and prepared according to the mass fraction of the alloy composition (Mg: 80wt.%, Ni: 10wt.%, Y: 10wt.%); the magnesium ingot, magnesium-yttrium alloy and magnesium-yttrium alloy were placed in a smelting crucible together, and the melt was heated to 730℃ under a mixed protective atmosphere of SF6 and CO2; then the magnesium alloy melt was placed at 680℃ for 20min before casting to obtain a magnesium alloy ingot.

[0035] S2: The magnesium alloy ingot was crushed into particles with a particle size of less than 2μm, and then the particles were loaded into a stainless steel ball mill pot in an argon atmosphere for dry grinding. Stainless steel balls with different particle sizes were used for ball milling at a speed of 450rad / min for 10h, with a pause of 15min every 15min to prevent the pot from overheating. After dry grinding, 20mL of ethanol was added to the pot in an argon atmosphere for wet grinding at a speed of 450rad / min for 1h, with a pause of 15min every 5min to prevent the pot from overheating. After wet grinding, the dispersion liquid containing the magnesium alloy powder was placed in a vacuum drying box at 50℃ for drying for 12h to obtain a hydrogen storage alloy.

[0036] Comparative Example 2.

[0037] S1: Weigh and prepare magnesium ingots, magnesium-yttrium alloys, magnesium-ytterbium alloys, and magnesium-nickel alloys according to the mass fractions of the alloy components (Mg: 80 wt.%, Ni: 10 wt.%, Y: 7 wt.%, Yb: 3 wt.%); place the magnesium ingots, magnesium-yttrium alloys, and magnesium-ytterbium alloys together in a melting crucible, and heat the melt to 730°C in a mixed protective atmosphere of SF6 and CO2; after the above alloys are melted, add the magnesium-nickel alloy, mechanically stir until the magnesium-nickel alloy is melted, and clean the surface of the melt; then, let the magnesium alloy melt stand at 680°C for 20 minutes before casting to obtain a hydrogen storage magnesium alloy ingot.

[0038] S2: The hydrogen storage magnesium alloy ingot was crushed into particles with a size less than 2 μm. The particles were then dry-milled in a stainless steel ball mill under an argon atmosphere. Stainless steel balls of varying sizes were used for milling at 450 rad / min for 10 hours, with 15-minute pauses every 15 minutes to prevent overheating. After dry milling, the magnesium alloy powder dispersion was dried in a 50°C vacuum oven for 12 hours to obtain an equiaxed magnesium alloy powder.

[0039] The hydrogen storage performance of the alloy was tested. The average hydrogen absorption capacity of the alloy after absorbing hydrogen for 5 minutes at 3 MPa and 3 MPa at different temperatures was 3.12 wt.% at 250°C and 3.85 wt.% at 340°C. The average dehydrogenation efficiency η of the alloy after dehydrogenation for 5 minutes at different temperatures and vacuum conditions reached 40.6% at 250°C and 90.2% at 340°C. The dehydrogenation rate η after dehydrogenation for 30 minutes at 250°C and vacuum conditions was 87.6%.

[0040] Example 1.

[0041] S1: Weigh and prepare magnesium ingots, magnesium-yttrium alloys, magnesium-ytterbium alloys, and magnesium-nickel alloys according to the mass fractions of the alloy components (Mg: 80 wt.%, Ni: 10 wt.%, Y: 7 wt.%, Yb: 3 wt.%); place the magnesium ingots, magnesium-yttrium alloys, and magnesium-ytterbium alloys together in a melting crucible, and heat the melt to 730°C in a mixed protective atmosphere of SF6 and CO2; after the above alloys are melted, add the magnesium-nickel alloy, mechanically stir until the magnesium-nickel alloy is melted, and clean the surface of the melt; then, let the magnesium alloy melt stand at 680°C for 20 minutes before casting to obtain a hydrogen storage magnesium alloy ingot.

[0042] like Figure 1The scanning electron microscope (SEM) images of the magnesium alloy ingots prepared in Comparative Example 1 and this embodiment are used to observe the microstructure of the hydrogen storage magnesium alloy ingots. It can be seen from the figure that the magnesium alloy ingot prepared in Example 1 includes α-Mg phase, LPSO phase, Mg2Ni phase and Mg2Yb phase. Among them, compared with the microstructure of the magnesium alloy without Yb addition in Comparative Example 1, the grain size of the second phase is significantly reduced, which proves that the introduction of the Mg2Yb phase helps to inhibit the coarsening and agglomeration of the second phase. The refined second phase can provide more phase interfaces as channels and cores for hydrogen diffusion, which can effectively shorten the diffusion path of hydrogen atoms and increase the diffusion rate of hydrogen inside the material, thereby helping to improve the kinetic process of hydrogen absorption and desorption.

[0043] S2: The hydrogen storage magnesium alloy ingot was crushed into particles with a size of less than 2 μm. The particles were then placed in a stainless steel ball mill under an argon atmosphere and dry-milled at 450 rad / min for 10 hours using stainless steel balls of varying sizes, with 15-minute pauses every 15 minutes to prevent overheating. After dry milling, 20 mL of ethanol was added to the mill under an argon atmosphere and wet-milled at 450 rad / min for 1 hour, with 15-minute pauses every 5 minutes to prevent overheating. After wet milling, the magnesium alloy powder dispersion was dried in a 50°C vacuum oven for 12 hours to produce the hydrogen storage alloy.

[0044] like Figure 2 The SEM images of the magnesium alloy powders prepared in Comparative Example 2 and this example show that the hydrogen storage alloy prepared in this example has a flaky powder structure with a thickness of approximately 10 μm. Compared with the equiaxed magnesium alloy powder prepared in Comparative Example 2, its specific surface area is significantly increased, significantly enhancing the contact interface between the material and hydrogen, thereby facilitating the adsorption of hydrogen atoms on its surface and their rapid diffusion into the interior. Furthermore, the flaky structure of the magnesium alloy prepared in this example generally exhibits a shorter diffusion path and higher surface activity, which helps reduce hydrogen diffusion resistance in the solid phase, improving the hydrogen absorption rate and the kinetics of the dehydrogenation reaction.

[0045] The hydrogen storage performance of hydrogen storage alloys is tested, such as Figure 3 Figures 2 and 3 show the hydrogen absorption kinetics curves of Example 1 and Comparative Example 1 under the test condition of 250°C. As can be seen from the figure, when absorbing hydrogen for 5 minutes and 30 minutes under a pressure of 3 MPa, the average hydrogen absorption amount of the hydrogen storage alloy prepared in Example 1 is 3.90 wt.% and 4.41 wt.%, respectively, which are both higher than the hydrogen absorption amount of the hydrogen storage alloy prepared in Comparative Example 1 (3.56 wt.% and 4.38 wt.%). Figure 4The hydrogen absorption kinetics curves of Example 1 and Comparative Example 1 under the test conditions of 340℃ can be seen from the figure, and the average hydrogen absorption amounts of the hydrogen storage alloy prepared in Example 1 are 4.89wt.% and 5.14wt.% at 5min and 30min under the pressure of 3MPa, respectively, which are higher than the hydrogen absorption amounts (4.19wt.% and 5.01wt.%) of the hydrogen storage alloy prepared in Comparative Example 1.

[0046] In summary, the hydrogen storage performance test further proves that the hydrogen absorption performance of the hydrogen storage material is significantly enhanced by constructing the Mg-Ni-Y-Yb multi-component alloy structure according to the present application, which is due to the synergistic effect of each component, structure regulation and phase boundary optimization during the hydrogen absorption process. Specifically, when the Ni element is introduced into the alloy, it can form the Mg2Ni phase with Mg, which can generate the reversible hydrogen storage compound Mg2NiH4, and the hydrogen diffusion rate of which is significantly higher than that of MgH2, and has a lower enthalpy of formation, which helps to reduce the hydrogen release temperature of the material; at the same time, the d orbit of Ni and the S orbit of hydrogen effectively hybridize, which can reduce the energy barrier required for hydrogen molecules to dissociate into atoms on the surface, thereby accelerating the hydrogen absorption reaction. When the Y element is introduced, on the one hand, it can absorb hydrogen to generate YH2 / YH3, which plays a "hydrogen pump" effect in the process, promoting the formation of MgH2 or Mg2NiH4 around; on the other hand, the Y element helps to form a long-period ordered stacking (LPSO) structure in the alloy, which makes Mg, Ni and Y uniformly distributed, significantly increases the number of phase boundaries, and provides more diffusion channels for hydrogen atoms, thereby improving the hydrogen absorption and desorption kinetics. When the Yb element is added, the LPSO structure is further refined, the phase boundary density is improved, and the Mg2Yb phase formed will introduce lattice distortion and interface atomic arrangement disorder in the matrix, which weakens the Mg-H bond strength, reduces the decomposition enthalpy of MgH2 from the thermodynamic point of view, and is beneficial to the release of hydrogen; in addition, the oxide such as Yb2O3 formed by Yb is more easily reduced by hydrogen than MgO, which helps to reduce the hindrance of the passivation layer on the alloy surface to hydrogen permeation, and further improves the hydrogenation reaction efficiency of the material, thereby significantly improving the overall hydrogen absorption capacity of the alloy.

[0047] As Figure 5 The hydrogen desorption kinetics curves of Example 1 and Comparative Example 1 under the vacuum condition of 250℃ can be seen from the figure, and the average hydrogen desorption efficiencies η (η = hydrogen desorption amount / total hydrogen absorption amount × 100%) of the hydrogen storage alloy prepared in Example 1 are 46.2% and 91.8% at 5min and 30min, respectively, which are higher than the average hydrogen desorption efficiencies (3.42% and 26.3%) of the hydrogen storage alloy prepared in Comparative Example 1; as Figure 6Figures 2 and 3 show the dehydrogenation kinetics curves of Example 1 and Comparative Example 1 under vacuum conditions at 340°C. It can be seen from the figure that after dehydrogenation for 5 minutes and 30 minutes, the average dehydrogenation efficiency η of the hydrogen storage alloy prepared in Example 1 is 98.2% and 99.8%, respectively, which are both higher than the average dehydrogenation efficiency of the hydrogen storage alloy prepared in Comparative Example 1 (86.4% and 97.8%).

[0048] It can be seen from this that the Mg-Ni-Y-Yb alloy prepared in this application has been significantly improved in terms of dehydrogenation efficiency and dehydrogenation rate compared to the Mg-Ni-Y alloy. This is mainly due to the fact that the introduction of the Yb element not only promotes the formation of key hydrogen storage phases such as Mg2Ni, but also significantly improves the thermal stability and hydrogen diffusion rate of the alloy by forming stable intermetallic compounds such as Mg2Yb. At the same time, it refines the grains, increases the number of grain boundaries, and constructs more interface channels that are conducive to hydrogen diffusion and desorption, thereby reducing the dehydrogenation activation energy and improving the reaction kinetics. At the same time, the dehydrogenation rate of the Mg-Ni-Y-Yb alloy increases significantly with increasing temperature and reaction time, indicating that it has excellent reaction activity and dehydrogenation persistence under thermal activation conditions. This performance advantage stems from the combined effect of multiple mechanisms such as multiphase synergy, interface activation, and hydrogen diffusion channel optimization in the alloy.

[0049] Example 2.

[0050] S1: Weigh and prepare magnesium ingot, magnesium yttrium alloy, magnesium ytterbium alloy and magnesium nickel alloy according to the mass fraction of the alloy components (Mg: 80wt.%, Ni: 10wt.%, Y: 6wt.%, Yb: 4wt.%); put the magnesium ingot, magnesium yttrium alloy and magnesium ytterbium alloy into a melting crucible together, and heat the melt to 740℃ under a mixed protective atmosphere of SF6 and CO2; after the above alloys are melted, add magnesium nickel alloy, stir mechanically until the magnesium nickel alloy is melted, and clean the surface of the melt; then let the magnesium alloy melt stand at 690℃ for 20 minutes before casting to obtain a hydrogen storage magnesium alloy ingot. Figure 7 This is a SEM image of the hydrogen storage magnesium alloy ingot prepared in this embodiment. It can be seen from the image that the magnesium alloy includes α-Mg phase, LPSO phase, Mg2Ni phase, and Mg2Yb phase.

[0051] S2: The hydrogen storage magnesium alloy ingot was crushed into particles with a particle size of less than 2 μm, and then the particles were loaded into a stainless steel ball mill tank in an argon atmosphere for dry grinding; stainless steel balls with different particle sizes were used at a speed of 400 rad / min for 10 h, with a 15 min pause every 15 min of operation. After dry grinding, 20 mL of ethanol was added to the tank in an argon atmosphere for wet grinding; the speed was 400 rad / min for 2 h, with a 15 min pause every 5 min of operation. The dispersion liquid containing the magnesium alloy powder was placed in a 50°C vacuum drying oven for 12 h to obtain a hydrogen storage alloy. The hydrogen storage alloy prepared in this example was subjected to hydrogen storage performance testing. The average hydrogen storage amount of the alloy was 4.02 wt.% (250°C) and 5.04 wt.% (340°C) at different temperatures under a pressure of 3 MPa for 5 min; the average dehydrogenation efficiency η reached 50.2% (250°C) and 98.9% (340°C) under vacuum conditions at different temperatures for 5 min. In particular, the dehydrogenation rate η reached 93.1% under vacuum conditions at 250°C for 30 min.

[0052] Example 3.

[0053] S1: The magnesium ingot, magnesium-yttrium alloy, magnesium-ytterbium alloy, and magnesium-nickel alloy were weighed and prepared according to the mass fraction of the alloy composition (Mg: 90 wt.%, Ni: 10 wt.%, Y: 4 wt.%, Yb: 6 wt.%); the magnesium ingot, magnesium-yttrium alloy, and magnesium-ytterbium alloy were placed together in a smelting crucible, and the melt was heated to 750°C under a mixed protective atmosphere of SF6 and CO2; after the above alloys were melted, the magnesium-nickel alloy was added, and mechanical stirring was performed until the magnesium-nickel alloy was melted, and the melt surface was cleaned; then the magnesium alloy melt was placed at 700°C for 20 min before casting to obtain a hydrogen storage magnesium alloy ingot. As Figure 8 The SEM image of the hydrogen storage magnesium alloy ingot prepared in this example is shown in the figure, and it can be seen from the figure that the magnesium alloy includes α-Mg phase, LPSO phase, Mg2Ni phase, and Mg2Yb phase.

[0054] S2: The hydrogen storage magnesium alloy ingot was crushed into particles with a size of less than 2 μm. The particles were then placed in a stainless steel ball mill under an argon atmosphere for dry grinding. Stainless steel balls of varying sizes were used for ball milling at 350 rad / min for 10 hours, with a 15-minute pause after every 15 minutes of operation. After dry milling, 20 mL of ethanol was added to the mill under an argon atmosphere for wet milling. The milling was continued at 350 rad / min for 3 hours, with a 15-minute pause after every 5 minutes of operation. The dispersion containing the magnesium alloy powder was dried in a vacuum drying oven at 50°C for 12 hours to obtain a hydrogen storage alloy. The hydrogen storage performance of the hydrogen storage alloy prepared in this example was tested. The average hydrogen absorption capacity of the alloy after absorbing hydrogen for 5 minutes at 3 MPa pressure at different temperatures was 3.82 wt.% (250°C) and 4.92 wt.% (340°C), respectively. The average dehydrogenation efficiency η of the alloy after dehydrogenation for 5 minutes under vacuum conditions at different temperatures reached 49.7% (250°C) and 97.8% (340°C), respectively. In particular, the dehydrogenation rate η reaches 92.9% when dehydrogenated at 250°C and vacuum conditions for 30 minutes.

[0055] Example 4.

[0056] S1: Weigh and prepare a magnesium ingot, magnesium-yttrium alloy, magnesium-ytterbium alloy, and magnesium-nickel alloy according to the mass fractions of the alloy components (Mg: 85 wt.%, Ni: 5 wt.%, Y: 4 wt.%, Yb: 6 wt.%); place the magnesium ingot, magnesium-yttrium alloy, and magnesium-ytterbium alloy together in a melting crucible and heat the melt to 740°C in a mixed protective atmosphere of SF6 and CO2; after the above alloys are melted, add the magnesium-nickel alloy, mechanically stir until the magnesium-nickel alloy is melted, and clean the melt surface; then, allow the magnesium alloy melt to stand at 690°C for 20 minutes before casting to obtain a hydrogen storage magnesium alloy ingot. Scanning electron microscopy (SEM) analysis of the hydrogen storage magnesium alloy ingot prepared in Example 1 revealed that the magnesium alloy comprises an α-Mg phase, a LPSO phase, a Mg2Ni phase, and a Mg2Yb phase.

[0057] S2: The hydrogen storage magnesium alloy ingot was crushed into particles with a size less than 2 μm. The particles were then placed in a stainless steel ball mill under an argon atmosphere and dry-milled. Stainless steel balls of varying sizes were used for ball milling at 400 rad / min for 10 hours, with 15-minute pauses every 15 minutes. After dry milling, 20 mL of ethanol was added to the mill under an argon atmosphere and wet-milled at 400 rad / min for 2 hours, with 15-minute pauses every 5 minutes. The dispersion containing the magnesium alloy powder was dried in a 50°C vacuum drying oven for 12 hours to obtain the hydrogen storage alloy. The hydrogen storage performance of the hydrogen storage alloy prepared in this embodiment was tested. The average hydrogen absorption capacity of the alloy after absorbing hydrogen for 5 minutes at 3 MPa and different temperatures was 3.76 wt.% (250°C) and 4.67 wt.% (340°C), respectively. The average dehydrogenation efficiency η of the alloy after dehydrogenation for 5 minutes under vacuum conditions at different temperatures reached 48.7% (250°C) and 97.0% (340°C), respectively. In particular, the dehydrogenation rate η reaches 92.3% when dehydrogenated at 250°C and vacuum conditions for 30 minutes.

[0058] Example 5.

[0059] S1: Weigh and prepare a magnesium ingot, magnesium-yttrium alloy, magnesium-ytterbium alloy, and magnesium-nickel alloy according to the mass fractions of the alloy components (Mg: 75 wt.%, Ni: 15 wt.%, Y: 6 wt.%, Yb: 4 wt.%); place the magnesium ingot, magnesium-yttrium alloy, and magnesium-ytterbium alloy together in a melting crucible and heat the melt to 740°C in a mixed protective atmosphere of SF6 and CO2; after the above alloys are melted, add the magnesium-nickel alloy, mechanically stir until the magnesium-nickel alloy is melted, and clean the melt surface; then, allow the magnesium alloy melt to stand at 690°C for 20 minutes before casting to obtain a hydrogen storage magnesium alloy ingot. Scanning electron microscopy (SEM) analysis of the hydrogen storage magnesium alloy ingot prepared in Example 1 revealed that the magnesium alloy comprises an α-Mg phase, a LPSO phase, a Mg2Ni phase, and a Mg2Yb phase.

[0060] S2: Crushing the hydrogen storage magnesium alloy ingot into particles with a particle size of less than 2 μm. Then, placing an appropriate amount of particles into a stainless steel ball mill in an argon atmosphere for dry grinding; using stainless steel balls of different particle sizes to ball mill at a speed of 350 rad / min for 10 hours, wherein a pause of 15 minutes is performed every 15 minutes of operation. After the dry grinding is completed, 20 mL of ethanol is added to the tank body in an argon atmosphere for wet grinding; ball milling is carried out at a speed of 350 rad / min for 3 hours, wherein a pause of 15 minutes is performed every 5 minutes of operation. The dispersion containing the magnesium alloy powder is placed in a vacuum drying oven at 50°C and dried for 12 hours to obtain a hydrogen storage alloy. The hydrogen storage performance of the hydrogen storage alloy prepared in this embodiment was tested. The average hydrogen absorption amount of the alloy when absorbing hydrogen for 5 minutes at different temperatures and 3MPa pressures was 3.61wt.% (250°C) and 4.56wt.% (340°C), respectively. The average dehydrogenation efficiency η of the alloy after dehydrogenation for 5 minutes at different temperatures and vacuum conditions reached 45.1% (250°C) and 94.2% (340°C), respectively. In particular, the dehydrogenation efficiency η reached 90.1% after dehydrogenation for 30 minutes at 250°C and vacuum conditions.

[0061] In summary, the present invention achieves the simultaneous improvement of hydrogen diffusion path and thermodynamic properties by constructing a Mg-Ni-Y-Yb multi-element alloy structure and utilizing multi-phase synergy, structural regulation and interface optimization of multiple elements, thereby significantly enhancing the hydrogen absorption and dehydrogenation performance of the hydrogen storage material; at the same time, the composite mechanical ball milling process is used to prepare a flaky powder structure hydrogen storage material, which significantly improves the hydrogen absorption and desorption kinetics of the alloy.

[0062] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0063] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hydrogen storage alloy, characterized in that Calculated by mass, it contains the following alloy components: 5-15 parts of nickel, 2-8 parts of yttrium, 2-8 parts of ytterbium, 68.8-91 parts of magnesium, and 0-0.2 parts of impurities.

2. A method for preparing a hydrogen storage alloy according to claim 1, characterized in that: The method comprises the following preparation steps: S1: weighing and mixing a magnesium ingot, a magnesium yttrium alloy, a magnesium ytterbium alloy, and a magnesium nickel alloy according to the alloy composition, placing the magnesium ingot, the magnesium yttrium alloy, and the magnesium ytterbium alloy into a melting crucible and heating and melting them; then adding the magnesium nickel alloy and stirring until the magnesium nickel alloy is melted, cleaning the surface of the melt, cooling the magnesium alloy melt and allowing it to stand before casting to obtain a hydrogen storage magnesium alloy ingot; S2: crushing the hydrogen storage magnesium alloy ingot, and placing the hydrogen storage magnesium alloy particles into a stainless steel ball mill for dry grinding; after the dry grinding, adding a solvent into the tank for wet grinding to obtain a dispersion containing magnesium alloy powder, and placing the dispersion in a vacuum drying oven for drying to obtain a hydrogen storage alloy.

3. The method for preparing a hydrogen storage alloy according to claim 2, wherein: The protective atmosphere during the heating and melting in S1 is a mixture of SF6 and CO2, and the heating and melting temperature is 730-750°C.

4. The method for preparing a hydrogen storage alloy according to claim 2, wherein: The cooling in S1 is to cool the temperature to 680-700°C.

5. The method for preparing a hydrogen storage alloy according to claim 2, wherein: The size of the hydrogen storage magnesium alloy ingot crushed in S2 is less than 2 μm.

6. The method for preparing a hydrogen storage alloy according to claim 2, wherein: The rotation speed of the dry grinding in S2 is 350-450 rad / min, dry grinding is performed every 30 minutes, each operation is 15 minutes, and the total dry grinding time is 10-20 hours.

7. The method for preparing a hydrogen storage alloy according to claim 2, wherein: The solvent in S2 is ethanol or acetone.

8. The method for preparing a hydrogen storage alloy according to claim 2, wherein: The rotation speed of the wet grinding in S2 is 350-450 rad / min, wherein the wet grinding is performed every 20 minutes, each operation is 5 minutes, and the total wet grinding time is 1-3 hours.

9. The method for preparing a hydrogen storage alloy according to claim 2, wherein: The atmosphere for both dry grinding and wet grinding in S2 was argon atmosphere.

Images