Preparation method of multiphase wrapped rare earth modified magnesium-nickel alloy solid hydrogen storage material

Abstract

The application belongs to the technical field of solid hydrogen storage materials, and discloses a preparation method of a rare earth modified magnesium-nickel alloy solid hydrogen storage material coated with a complex phase; magnesium-nickel alloy powder, a rare earth compound and carboxymethyl cellulose are wet-milled, and then spray-dried to obtain alloy microsphere precursors after low-temperature heat treatment; a shell slurry is prepared by heating and stirring of modified silicone resin, elemental silicon powder and acetone; the alloy microsphere precursors are coated with the shell slurry through an equal-volume impregnation process, and then dried and subjected to high-temperature heat treatment under microwave conditions in a protective atmosphere, so that the rare earth modified magnesium-nickel alloy solid hydrogen storage material coated with the complex phase is finally obtained. The hydrogen storage material prepared by the application has high hydrogen storage density, low hydrogen release temperature and simple preparation process.

Description

Technical Field

[0001] This invention belongs to the field of solid hydrogen storage materials technology, specifically relating to a method for preparing a multiphase-encapsulated rare earth-modified magnesium-nickel alloy solid hydrogen storage material. Background Technology

[0002] As the global energy structure shifts towards cleaner and lower-carbon energy sources, hydrogen energy, as a pollution-free and highly efficient secondary energy source, is becoming a core component of the future energy system. Solid-state hydrogen storage, with its advantages of high safety, high storage density, and convenient transportation, has greater potential for industrial application compared to high-pressure gaseous hydrogen storage and cryogenic liquid hydrogen storage.

[0003] In solid-state hydrogen storage technology, magnesium-based hydrogen storage alloys have attracted much attention due to their high hydrogen storage capacity, abundant resources, and low cost. However, traditional Mg-Ni alloy hydrogen storage materials suffer from several technical problems, including: high hydrogen desorption temperatures, which limit their widespread application in low-temperature and low-pressure scenarios; poor cycle stability, where alloy particles tend to agglomerate and oxidize during repeated hydrogen absorption and desorption, leading to rapid degradation of hydrogen storage performance; and poor kinetic performance, with slow hydrogen absorption and desorption rates, making it difficult to meet the rapid hydrogen storage requirements of practical applications.

[0004] To address the aforementioned issues, existing technologies often employ rare-earth modification or surface coating to optimize Mg-Ni alloys. Rare-earth elements (such as La, Ce, and Y) possess unique electronic structures that can improve the crystal structure of Mg-Ni alloys, reduce the activation energy for hydrogen absorption and desorption, and enhance hydrogen storage kinetics and cycle stability. Studies have shown that rare-earth oxides such as La₂O₃ and CeO₂ can improve the discharge capacity and cycle life of hydrogen storage electrodes, exerting a good catalytic effect and inhibiting further alloy oxidation. Surface coating, on the other hand, forms a protective film on the alloy surface, isolating it from air and moisture, reducing alloy oxidation, and simultaneously inhibiting particle agglomeration. Existing magnesium-based hydrogen storage materials often employ single-carbon coating or pure ceramic phase coating. Single-carbon coatings lack sufficient density to withstand the volume expansion stress during hydrogen absorption and desorption processes in magnesium-based alloys. While single-pure ceramic phase coatings are dense, they suffer from obstructed hydrogen diffusion channels, mismatched thermal expansion coefficients with the magnesium matrix leading to interfacial cracking, and poor cycle performance.

[0005] The patent document CN121372424A, entitled "A Metal Oxide / Carbon / Nickel Composite Material, its Preparation Method and its Application in Magnesium-Based Hydrogen Storage Materials," discloses a method for preparing a Nix-CeMOF precursor using cerium source powder, nickel source powder, and trimesic acid as raw materials. After calcination in a hydrogen-argon mixed atmosphere, a CeO2 / C / NiX composite material is obtained. This material is then mixed with MgH2 through a secondary ball milling process to obtain a magnesium-based hydrogen storage material. This method requires a solvothermal reaction to synthesize a porous crystalline MOF, solid-liquid separation, washing and drying, atmospheric calcination, and finally, high-energy ball milling and composite processing. The preparation process involves multiple solid-liquid separation steps and heat treatment under different atmospheres, making it complex.

[0006] The patent document "A Hydrogen Storage Alloy Composite Material and Its Preparation Method" (CN121880064A) discloses a method for preparing a hydrogen storage alloy composite material with a carbon coating by using hydrogen storage alloy powder, organic solvent, metal salt, and organic ligands as raw materials. This method involves in-situ growth of MOF material precursors on the alloy surface through ball milling, followed by high-temperature calcination for carbonization. This method requires centrifugation and vacuum drying after ball milling, followed by high-temperature calcination to carbonize the organic ligands and form a carbon layer. The preparation process involves multiple solid-liquid separation steps and prolonged heat treatment, making it complex. Furthermore, the single carbon coating layer formed by this method lacks sufficient density and rigidity to withstand the enormous volume expansion stress during hydrogen absorption and desorption of the magnesium-nickel alloy, easily leading to shell cracking and pulverization failure after repeated cycles. Additionally, this document does not introduce elemental lanthanide metals for in-situ alloying modification, failing to fundamentally address the thermodynamic bottleneck of high hydrogen desorption temperature and slow kinetics in magnesium-based materials.

[0007] The patent document "A Magnesium-Based Hydrogen Storage Material and Its Preparation Method" (CN121880072A) discloses a method using Mg-5Ni alloy powder and samarium powder as raw materials. The raw materials are mixed and then subjected to dry ball milling, causing the samarium powder to be coated by the Mg-5Ni alloy surface, forming a core-shell structured composite powder. This method requires a long dry ball milling process of 20-40 hours, resulting in high energy consumption and a tendency for powder agglomeration due to cold welding, leading to low preparation efficiency. Furthermore, this method relies solely on the ductile magnesium alloy matrix to physically encapsulate the internal rare-earth samarium powder, failing to construct a dense protective shell around the alloy particles. During repeated hydrogen absorption and desorption cycles, the outer magnesium matrix inevitably undergoes severe pulverization and oxidation deactivation, failing to simultaneously achieve rare-earth catalytic modification and long-term anti-pulverization protection.

[0008] Therefore, developing a multiphase encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material that combines high hydrogen storage capacity, low hydrogen release temperature, excellent cycle stability, and simple preparation process that can be industrially produced has become an urgent technical problem to be solved in the field of solid hydrogen storage materials. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing Mg-Ni hydrogen storage materials, such as high hydrogen release temperature, poor cycle stability, and unsatisfactory kinetic performance, as well as the technical defects of existing coating technologies, such as uneven coating, weak bonding between the shell and the matrix, and inability to take into account multiple aspects of performance. The invention provides a method for preparing a multiphase-encapsulated rare earth modified magnesium-nickel alloy solid hydrogen storage material with excellent comprehensive performance, simple preparation process, and industrialization capability.

[0010] This invention involves wet ball milling of magnesium-nickel alloy powder, rare earth compounds, and carboxymethyl cellulose, followed by spray drying and low-temperature heat treatment to obtain an alloy microsphere precursor. A shell slurry is prepared by heating and stirring organosilicon resin, elemental silicon powder, and acetone. The shell slurry is then coated onto the surface of the alloy microsphere precursor using an equal-volume impregnation process. After drying in a fluidized bed, the precursor is subjected to high-temperature heat treatment under a protective atmosphere and microwave conditions to obtain the final product.

[0011] This invention utilizes carboxymethyl cellulose-assisted spray granulation to construct millimeter-scale spherical structures. A dense coating layer is formed between the SiC-CNTs multiphase generated from the pyrolysis of modified organosilicon resin and elemental silicon, effectively suppressing pulverization and oxidation during the hydrogen absorption and desorption cycle of magnesium-nickel alloys. Simultaneously, the introduction of rare earth elements significantly improves the thermodynamic and kinetic properties of the alloy's hydrogen absorption and desorption. This invention has the advantages of simple preparation process, low production cost, and environmental friendliness.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] A method for preparing a multiphase-encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material includes the following steps:

[0014] Step 1: Preparation of rare earth modified hydrogen storage alloy microspheres: 90-98 parts by weight of magnesium-nickel alloy powder, 2-10 parts by weight of rare earth compound, and 1-2 parts by weight of carboxymethyl cellulose are wet-milled in a high-energy ball mill for 1-4 hours to prepare a composite slurry. The composite slurry is then spray-dried to produce alloy millimeter-sized particles. The resulting alloy particles are then heat-treated at 100-200℃ for 1-2 hours under vacuum to prepare the alloy microsphere precursor.

[0015] Step 2, Preparation of shell slurry: Modified organosilicon resin, elemental silicon powder and acetone are mixed in a weight ratio of 35~50:2~5:1 and stirred at 80~120℃ for 0.5~1.25h using a heated magnetic stirrer to obtain shell slurry;

[0016] Step 3, Multiphase Encapsulation and Product Preparation: The obtained alloy microsphere precursor is rolled in a shell slurry for 1-5 seconds, and then dried in a fluidized bed dryer to form a precursor spherical powder with a core-shell structure; the precursor spherical powder is then heat-treated at 800-1100℃ for 0.5-2 hours under a protective atmosphere microwave condition to obtain the multiphase encapsulated rare earth modified magnesium-nickel alloy solid hydrogen storage material.

[0017] In step one, the magnesium-nickel alloy powder has a particle size of 10-50 μm and an atomic ratio of Mg to Ni of 2:1.

[0018] A Mg:Ni atomic ratio of 2:1 (Mg2Ni) is the optimal composition for magnesium-nickel hydrogen storage alloys. Mg2Ni is the high-hydrogen-storage main phase, theoretically possessing the highest hydrogen storage capacity, ensuring the material exhibits high hydrogen storage capacity. This ratio also results in a moderate number of grain boundaries, facilitating the formation of nanocatalytic phases of rare earth oxides / rare earth metals at the grain boundaries, significantly reducing the activation energy for hydrogen absorption and desorption and accelerating the kinetics. Simultaneously, this ratio also suppresses free Mg / Ni, lowering the hydrogen desorption temperature.

[0019] The rare earth compound in step one is one or two of La2O3, CeO2, Y2O3 or LaH3;

[0020] In step two, the modified silicone resin is one or two of Mo-modified silicone resin, Ce-modified silicone resin, and La-modified silicone resin.

[0021] The elemental silicon powder mentioned in step two has a particle size of ≤100nm and a purity of ≥99.99%.

[0022] In step three, the protective atmosphere is one or two of argon, nitrogen, and reducing atmosphere.

[0023] This invention uses carboxymethyl cellulose as a binder and pore-forming agent to construct millimeter-sized spherical structures from micron-sized powder, eliminating the agglomeration of fine powder. Through spray drying and heat treatment processes, residual moisture on the surface of alloy particles is removed and the carboxymethyl cellulose undergoes partial cross-linking and carbonization, giving the alloy microsphere precursor a certain mechanical strength.

[0024] In this process, the modified organosilicon resin is decomposed into a SiC and carbon nanotube (CNTs) multiphase framework during microwave heat treatment. It reacts and sinters with the added elemental silicon powder to form a dense SiC-CNTs multiphase coating layer on the outside of the alloy microspheres, which is permeable to hydrogen. This multiphase coating layer greatly improves the fracture toughness of the shell, enabling it to absorb and buffer the volume expansion stress generated when the magnesium-nickel alloy absorbs and desorbs hydrogen.

[0025] The rare earth compounds used are microwave-heated under a protective atmosphere, generating strong dielectric loss within the magnesium-nickel alloy to achieve rapid in-situ alloying. The rare earths agglomerate at the alloy grain boundaries to form a catalytic nanophase, improving the morphology, particle size, and structural uniformity of the Mg-Ni alloy microspheres, reducing the activation energy for hydrogen absorption and desorption, providing a stable and regular matrix for subsequent shell coating, and simultaneously enhancing the dispersibility of raw materials within the alloy microspheres, providing sufficient active sites for hydrogen storage reactions.

[0026] This invention employs a design combining rare earth modification and multiphase encapsulation. The addition of rare earth compounds (La2O3, CeO2, etc.) improves the crystal structure of Mg-Ni alloys, reduces the activation energy for hydrogen absorption and desorption, and enhances hydrogen storage kinetics and cycle stability. The multiphase shell (modified organosilicon resin + elemental silicon powder) effectively isolates air and moisture, inhibits alloy particle agglomeration and oxidation, reduces the erosion of the core alloy, and alleviates volume expansion during hydrogen absorption and desorption, significantly improving the structural stability and cycle life of the material. Simultaneously, the use of Mo-modified organosilicon resin further enhances the density and hydrogen barrier properties of the shell, synergistically achieving high hydrogen storage capacity, low hydrogen desorption temperature, and optimized cycle stability. This addresses the core technical challenges of existing Mg-Ni hydrogen storage materials and offers superior overall performance compared to existing single-phase encapsulation or multiphase mixing technologies.

[0027] The beneficial effects of this invention are as follows: The hydrogen storage material prepared by this invention has high hydrogen storage density, good safety, and stable cycle performance, and can be widely used in hydrogen energy storage, fuel cells, new energy vehicles, portable energy storage devices, and other fields, with significant economic value and social benefits. The preparation process, which combines wet ball milling, spray drying, equal-volume impregnation, and microwave heat treatment, is simple to operate, highly controllable, and can achieve large-scale industrial production. Among them, the equal-volume impregnation process ensures uniform shell coating and tight bonding with the substrate, while microwave heat treatment can quickly solidify the shell, shorten the preparation cycle, and reduce production costs. Compared with existing ball milling and single coating processes, this process is more innovative and practical. Attached Figure Description

[0028] Figure 1 Microstructure of a multiphase-encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material Detailed Implementation

[0029] The following examples illustrate the embodiments and features of the present invention, but the present invention is not limited to the following embodiments.

[0030] Example 1:

[0031] A method for preparing a multiphase-encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material:

[0032] Step 1: Preparation of rare earth modified hydrogen storage alloy microspheres: 90 parts by weight of magnesium-nickel alloy powder, 10 parts by weight of rare earth compound La2O3, and 1 part by weight of carboxymethyl cellulose were wet-milled in a high-energy ball mill for 1 hour to prepare a composite slurry. The composite slurry was then spray-dried to produce alloy millimeter-sized particles. The resulting alloy particles were then heat-treated at 100°C for 2 hours under vacuum to prepare the alloy microsphere precursor.

[0033] Step 2, Preparation of shell slurry: Mo-modified organosilicon resin, elemental silicon powder and acetone are mixed in a weight ratio of 35:2:1 and stirred at 80°C for 2 hours using a heated magnetic stirrer to obtain shell slurry;

[0034] Step 3, Multiphase Encapsulation and Product Preparation: The obtained alloy microsphere precursor is rolled in a shell slurry for 2 seconds, and then dried in a fluidized bed dryer to form a precursor spherical powder with a core-shell structure; the precursor spherical powder is heat-treated at 1100℃ for 0.5 h under microwave conditions in an argon atmosphere to obtain the multiphase encapsulated rare earth modified magnesium-nickel alloy solid hydrogen storage material.

[0035] The hydrogen storage capacity of the prepared solid hydrogen storage material is 5.5~6.5wt%, and the initial hydrogen release temperature is 210~220℃.

[0036] Example 2:

[0037] A method for preparing a multiphase-encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material:

[0038] Step 1: Preparation of rare earth modified hydrogen storage alloy microspheres: 92 parts by weight of magnesium-nickel alloy powder, 8 parts by weight of rare earth compound CeO2, and 1.25 parts by weight of carboxymethyl cellulose were wet-milled in a high-energy ball mill for 2 hours to prepare a composite slurry. The composite slurry was then spray-dried to produce alloy millimeter-sized particles. The resulting alloy particles were then heat-treated at 150°C for 1.5 hours under vacuum to prepare the alloy microsphere precursor.

[0039] Step 2, Preparation of shell slurry: Ce-modified organosilicon resin, elemental silicon powder and acetone are mixed in a weight ratio of 40:3:1 and stirred at 100°C for 1.5 hours using a heated magnetic stirrer to obtain shell slurry;

[0040] Step 3, Multiphase Encapsulation and Product Preparation: The obtained alloy microsphere precursor is rolled in a shell slurry for 2 seconds, and then dried in a fluidized bed dryer to form a precursor spherical powder with a core-shell structure; the precursor spherical powder is heat-treated at 1000℃ for 0.75h under a nitrogen atmosphere and microwave conditions to obtain the multiphase encapsulated rare earth modified magnesium-nickel alloy solid hydrogen storage material.

[0041] The prepared solid hydrogen storage material has a hydrogen storage capacity of 5.8~7.0 wt% and an initial hydrogen release temperature of 205~215℃. Example 3:

[0042] A method for preparing a multiphase-encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material:

[0043] Step 1: Preparation of rare earth modified hydrogen storage alloy microspheres: 95 parts by weight of magnesium-nickel alloy powder, 5 parts by weight of rare earth compound Y₂O₃, and 1.5 parts by weight of carboxymethyl cellulose were wet-milled in a high-energy ball mill for 3 hours to prepare a composite slurry. The composite slurry was then spray-dried to produce alloy millimeter-sized particles. The resulting alloy particles were then heat-treated at 150°C for 1 hour under vacuum to prepare the alloy microsphere precursor.

[0044] Step 2, Preparation of shell slurry: La-modified organosilicon resin, elemental silica powder and acetone are mixed in a weight ratio of 45:4:1 and stirred at 110°C for 1 hour using a heated magnetic stirrer to obtain shell slurry;

[0045] Step 3, Multiphase Encapsulation and Product Preparation: The obtained alloy microsphere precursor is rolled in a shell slurry for 3 seconds, and then dried in a fluidized bed dryer to form a precursor spherical powder with a core-shell structure; the precursor spherical powder is heat-treated at 900℃ for 1 hour under a reducing atmosphere and microwave conditions to obtain the multiphase encapsulated rare earth modified magnesium-nickel alloy solid hydrogen storage material.

[0046] The hydrogen storage capacity of the prepared solid hydrogen storage material is 6~7.3wt%, and the initial hydrogen release temperature is 200~210℃.

[0047] Example 4:

[0048] A method for preparing a multiphase-encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material:

[0049] Step 1: Preparation of rare earth modified hydrogen storage alloy microspheres: 98 parts by weight of magnesium-nickel alloy powder, 2 parts by weight of rare earth compounds LaH3 and La2O3, and 2 parts by weight of carboxymethyl cellulose were wet-milled in a high-energy ball mill for 4 hours to prepare a composite slurry. The composite slurry was then spray-dried to produce alloy millimeter-sized particles. The resulting alloy particles were then heat-treated at 200℃ for 1 hour under vacuum to prepare the alloy microsphere precursor.

[0050] Step 2, Preparation of shell slurry: La-modified organosilicon resin and Mo-modified organosilicon resin, elemental silicon powder and acetone are mixed in a weight ratio of 50:5:1 and stirred at 120°C for 0.5 h using a heated magnetic stirrer to obtain shell slurry.

[0051] Step 3, Multiphase Encapsulation and Product Preparation: The obtained alloy microsphere precursor is rolled in a shell slurry for 4 seconds, and then dried in a fluidized bed dryer to form a precursor spherical powder with a core-shell structure; the precursor spherical powder is heat-treated at 800℃ for 1 hour under reducing atmosphere and nitrogen atmosphere microwave conditions to obtain multiphase encapsulated rare earth modified magnesium-nickel alloy solid hydrogen storage material.

[0052] The prepared solid hydrogen storage material has a hydrogen storage capacity of 6.2~7.5wt% and an initial hydrogen release temperature of 195~205℃. This preparation method has the following advantages: the raw materials are readily available, thus requiring lower production costs; the preparation process only requires ball milling, spray drying, impregnation, drying, and microwave sintering, thus the process is simple; and the prepared multiphase-coated rare earth-modified magnesium-nickel alloy solid hydrogen storage material has excellent hydrogen storage capacity.

[0053] The parts of this invention not described in detail are prior art. The above embodiments will help those skilled in the art to further understand this invention, but do not limit this invention in any way. Various changes in form, detail, or equivalents made using this invention without departing from the scope of the appended claims are all within the protection scope of this invention.

Claims

1. A method for preparing a multiphase-encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material, characterized in that: Step 1: Preparation of rare earth modified hydrogen storage alloy microspheres: 90-98 parts by weight of magnesium-nickel alloy powder, 2-10 parts by weight of rare earth compound, and 1-2 parts by weight of carboxymethyl cellulose are wet-milled in a high-energy ball mill for 1-4 hours to prepare a composite slurry. The composite slurry is then spray-dried to produce alloy millimeter-sized particles. The resulting alloy particles are then heat-treated at 100-200℃ for 1-2 hours under vacuum to prepare the alloy microsphere precursor. Step 2, Preparation of shell slurry: Modified organosilicon resin, elemental silicon powder and acetone are mixed in a weight ratio of 35~50:2~5:1 and stirred at 80~120℃ for 0.5~1.25h using a heated magnetic stirrer to obtain shell slurry; Step 3, Multiphase Encapsulation and Product Preparation: The obtained alloy microsphere precursor is rolled in a shell slurry for 1-5 seconds, and then dried in a fluidized bed dryer to form a precursor spherical powder with a core-shell structure; the precursor spherical powder is then heat-treated at 800-1100℃ for 0.5-2 hours under a protective atmosphere microwave condition to obtain this multiphase encapsulated rare earth modified magnesium-nickel alloy solid hydrogen storage material.

2. The method for preparing a multiphase coated solid-state hydrogen storage material of rare earth modified magnesium-nickel alloy according to claim 1, characterized in that: In step one, the magnesium-nickel alloy powder has a particle size of 10~50μm and the atomic ratio of Mg to Ni is 2:

1.

3. The method for preparing a multiphase coated solid-state hydrogen storage material of rare earth modified magnesium-nickel alloy according to claim 1, characterized in that: The rare earth compounds are one or two of La2O3, CeO2, Y2O3 or LaH3.

4. The method for preparing a multiphase coated solid-state hydrogen storage material of rare earth modified magnesium-nickel alloy according to claim 1, characterized in that: In step two, the modified silicone resin is one or two of Mo-modified silicone resin, Ce-modified silicone resin, and La-modified silicone resin.

5. The preparation method of a multiphase-encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material according to claim 1, characterized in that: The particle size of the elemental silicon powder is ≤100nm, and the purity is ≥99.99%.

6. The method for preparing a multiphase-encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material according to claim 1, characterized in that: In step three, the protective atmosphere is one or two of the following: argon atmosphere, nitrogen atmosphere, and reducing atmosphere.

7. The method for preparing a multiphase-encapsulated rare-earth modified magnesium-nickel alloy solid hydrogen storage material according to claim 1, characterized in that: Modified organosilicon resin is decomposed into a SiC and carbon nanotube (CNT) composite framework during microwave heat treatment. It reacts and sinters with added elemental silicon powder to form a dense SiC-CNT composite coating layer on the outside of the alloy microspheres, which is permeable to hydrogen.

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