A high capacity Mg-Y-Al-Sn based solid-state hydrogen storage composite material and a preparation method thereof

Abstract

The application relates to a high-capacity Mg-Y-Al-Sn-based solid-state hydrogen storage composite material and a preparation method thereof, and belongs to the technical field of hydrogen storage materials. The application solves one of the problems in the prior art, such as high thermodynamic stability of a hydrogen storage material, complex activation process, high dissociation temperature, slow hydrogenation / dehydrogenation kinetics and the like. The application discloses a Mg-based solid-state hydrogen storage composite material, which is composed of 100 parts of Mg 94‑x Y x Al 6‑y Sn y , 2-6 parts of AlF3 and Cr2O3 and other inevitable impurities; in the formula, x and y are atomic ratios, and 1<=x<=4 and 0.5<=y<=3. The high-capacity Mg-Y-Al-Sn-based solid-state hydrogen storage composite material has high hydrogen absorption and desorption capacity and excellent hydrogen absorption and desorption kinetics; the preparation process is simple and easy to operate, is suitable for large-scale preparation, and can be widely applied to a hydrogen fuel cell field as a hydrogen storage / hydrogen supply carrier.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage materials technology, and in particular to a high-capacity Mg-Y-Al-Sn-based solid hydrogen storage composite material and its preparation method. Background Technology

[0002] Over-reliance on fossil fuels, coupled with limited fossil fuel shortages and increasingly severe environmental pollution, has led to a serious energy and environmental crisis, making the development of clean and renewable energy sources an urgent priority. Hydrogen is the most abundant element, containing a high amount of chemical energy per unit mass, and produces energy and water as byproducts in clean and environmentally friendly reactions. Therefore, hydrogen is considered a promising renewable energy source that can effectively address the energy crisis and environmental pollution problems. However, hydrogen's low chemical energy per unit volume limits its commercial application as a fuel. Consequently, many solutions have been researched, but the lack of safe and efficient hydrogen storage materials remains a significant technical challenge for the industrial applications of hydrogen in fuel cell vehicles and portable electronic products.

[0003] Hydrogen storage methods should meet the following requirements: large hydrogen storage capacity per unit volume and per unit mass, rapid hydrogen release rate at relatively low temperatures, and long cycle life. Commonly used hydrogen storage methods include high-pressure cylinder storage, liquid hydrogen storage, and low-pressure hydride solid-state storage. However, due to the large volume of compressed hydrogen or the serious leakage caused by liquid hydrogen vaporization, both methods have their own problems. Solid-state hydrogen storage technology, with its advantages of low cost, good safety, high energy density, and large capacity, is considered an attractive development direction for on-board hydrogen source systems.

[0004] Currently, many hydrogen storage materials are well-known, but none meet all the performance requirements set by the U.S. Department of Energy (DOE) for vehicle applications. Among metal hydrides, MgH2 is the most promising candidate for on-board hydrogen storage due to its large hydrogen storage capacity (7.6 wt.%), low cost, light weight, non-toxicity, high density, and good reversibility. However, some drawbacks of MgH2, such as its high thermodynamic stability (i.e., high Mg-H bond strength), complex activation process, high dissociation temperature, and slow hydrogenation / dehydrogenation kinetics, hinder its widespread application in the automotive field. To overcome these drawbacks, extensive research has been conducted on reducing the decomposition temperature of MgH2, accelerating adsorption kinetics, and improving its thermodynamic properties through methods such as reducing grain size, adding catalysts, mechanical ball milling, alloying, and surface modification. Mechanical ball milling and melt quenching are considered very effective techniques for reducing particle and / or grain size.

[0005] To date, various hydrogen storage materials suffer from one or more of the following problems: high thermodynamic stability, complex activation process, high dissociation temperature, and slow hydrogenation / dehydrogenation kinetics. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide a high-capacity Mg-Y-Al-Sn-based solid hydrogen storage composite material to solve one of the problems of existing hydrogen storage materials, such as high thermodynamic stability, complex activation process, high dissociation temperature, and slow hydrogenation / dehydrogenation kinetics.

[0007] This invention discloses a Mg-Y-Al-Sn-based solid hydrogen storage composite material, characterized in that its composition, by mass parts, is: 100 parts Mg 94-x Y x Al 6-y Sn y 2-6 parts AlF3 and Cr2O3, and other unavoidable impurities; where x and y are atomic ratios, and 1≤x≤4, 0.5≤y≤3.

[0008] Preferably, its composition, by mass parts, is: 100 parts Mg 94-x Y x Al 6-y Sn y 3-5 parts of AlF3 and Cr2O3 and other unavoidable impurities; where x and y are atomic ratios, and 2≤x≤3, 1≤y≤2.

[0009] Specifically, x = 2 and y = 2.

[0010] Specifically, the content of AlF3 and Cr2O3 is 5 parts by mass.

[0011] Specifically, the mass ratio of AlF3 to Cr2O3 is 1:1.

[0012] The present invention also discloses a method for the above-mentioned hydrogen storage composite material, comprising the following steps:

[0013] S1: According to formula Mg 94-x Y x Al 6-y Sn y The ingredients are prepared with a metal purity of ≥99.5%;

[0014] S2: The raw materials are melted by electric arc melting, induction heating melting or other heating methods, and the molten alloy is poured into a copper mold to obtain a master alloy ingot;

[0015] S3: Place the ingot prepared in step S2 into a quartz tube with a slit at the bottom, and induction heat it until the ingot is completely melted. Use the pressure of the protective gas to spray the liquid alloy from the slit at the bottom of the quartz tube onto the surface of the rotating water-cooled copper roller to form a fast-quenched alloy strip.

[0016] S4: After mechanically crushing the fast-quenched alloy strip and passing it through a 200-mesh sieve, the small particles retained on the sieve are loaded into a ball mill jar together with the catalyst AlF3+Cr2O3 and stainless steel grinding balls. After ball milling, Mg-Y-Al-Sn based solid hydrogen storage composite material is obtained.

[0017] Specifically, in step S1, Mg, Y and Sn are added in addition to a loss-on-burn amount of 5%-10% of their weight calculated according to the ingredients.

[0018] Specifically, in step S2, the melting operation involves the following steps: The weighed bulk metal is placed in a magnesium oxide crucible within a medium-frequency induction furnace according to the designed process. Bulk rare earth Y and electrolytic Al are placed at the bottom of the crucible, metallic Sn is placed on top of the electrolytic Al, and bulk Mg is placed on the top layer. A vacuum of 1×10⁻⁶ is then applied. -2 -5×10 -5 A pressure of 0.01-0.1 MPa is introduced as a protective gas, which is high-purity helium or a helium-argon mixture with a volume ratio of 1:1. The temperature is then increased to 1400-1550℃ to obtain molten Mg. 94-x Y x Al 6-y Sn y Liquid master alloy, hold for 1-5 minutes.

[0019] Specifically, the linear speed of the water-cooled copper roller in step S3 is 10-30 m / s, and the thickness of the formed fast-quenched alloy strip is 50-150 μm, and the width is 2-30 mm.

[0020] Specifically, in step S4, the ball milling process is as follows: after evacuating the ball mill jar, high-purity argon gas is introduced, and the ball mill is run in an all-around planetary high-energy ball mill for 3-5 hours with a ball-to-material ratio of 15-25:1 and a rotation speed of 300-500 rpm; during the ball milling process, the ball mill is stopped for 0.5 hours every hour of operation.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] a) The hydrogen storage composite material disclosed in this invention has high hydrogen storage capacity and excellent hydrogen absorption and desorption performance. This invention achieves alloying by adding trace amounts of rare earth element Y, alkaline earth metal Al, and Sn. Mg and Al can form Mg... 17 Al 12 In magnesium alloys, Sn and Mg can form the Mg2Sn phase, and the resulting intermetallic compounds can significantly improve the thermodynamic and kinetic properties of hydrogen absorption and desorption. Y and Al can form YH2 / YH3 and AlH3 hydrides with hydrogen, and these hydrides have a significant catalytic effect on the hydrogen absorption and desorption process of Mg-based alloys.

[0023] b) The surface state of hydrogen storage materials has a significant impact on solid-state hydrogen storage. In this invention, after mechanically crushing the rapidly quenched alloy sheet, a small amount of (AlF3+Cr2O3) catalyst is added and ball milling is performed for a short time. While maintaining the microstructure of the rapidly quenched alloy, the surface state of the rapidly quenched alloy is improved, resulting in a significant increase in surface roughness and the appearance of high-density crystal defects. This further improves the thermodynamics and kinetics of hydrogen absorption and desorption of the alloy / composite material, overcoming the problem that the surface of the rapidly quenched alloy strip is smooth and has few defects, which is not conducive to improving hydrogen absorption and desorption performance.

[0024] c) The composite hydrogen storage material disclosed in this invention has excellent hydrogen absorption and desorption kinetics and thermodynamic properties. Compared with existing hydrogen storage materials, its thermodynamic stability is significantly reduced (i.e., excellent hydrogen desorption kinetics) and its dissociation temperature is reduced (i.e., it has better hydrogen absorption and desorption performance, especially hydrogen desorption performance, at the same temperature). Moreover, the composite hydrogen storage material can be obtained without a complex activation process.

[0025] d) The preparation process and equipment / instruments of the composite hydrogen storage material of the present invention adopt the relatively mature operation and equipment at present, which are easy to implement, and various raw materials are readily available, making them suitable for large-scale preparation and wide-ranging applications.

[0026] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0027] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0028] Figure 1 This is the rapidly quenched alloy strip from Example 1;

[0029] Figure 2 The XRD diffraction patterns of the as-cast alloys in Examples 1-6 are shown below.

[0030] Figure 3 The SEM morphology of the ball-milled composite powders in Examples 1-6 is shown.

[0031] Figure 4 The XRD diffraction patterns of the ball-milled composite powders in Examples 1-6 are shown below.

[0032] Figure 5 The HRTEM morphology of the ball-milled composite powders in Examples 1-6 is shown. Detailed Implementation

[0033] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0034] A specific embodiment of the present invention discloses a Mg-Y-Al-Sn-based solid hydrogen storage composite material, the composition of which is 100 parts by mass of Mg 94-x Y x Al 6-y Sn y 2-6 parts (AlF3+Cr2O3) and other unavoidable impurities; where x and y are atomic ratios, and 1≤x≤4, 0.5≤y≤3.

[0035] This invention reveals that elemental substitution can reduce the thermal stability of Mg-based alloy hydrides and improve their hydrogen absorption and desorption kinetics. The specific mechanisms of action of each component are as follows:

[0036] Y: Replacing Mg with rare earth element Y can reduce the stability of alloy hydrides. Since rare earth element Y can form highly stable YH2 when absorbing hydrogen, this hydride has a good catalytic effect on the hydrogen absorption and desorption of Mg-based alloys.

[0037] Al, Sn: Adding small amounts of the metal elements Al and Sn simultaneously can form Mg 17 Al 12 The presence of the Mg2Sn phase can significantly improve the hydrogen absorption and desorption kinetics of Mg-based alloys and, to some extent, enhance the hydrogen absorption and desorption thermodynamics of the alloys.

[0038] AlF3: The catalytic effect of AlF3 mainly lies in its very low hardness and good stability. It has a good lubricating effect during ball milling, which can effectively prevent the abrasive from sticking to the inner wall of the ball mill jar during the ball milling process.

[0039] Cr2O3: The catalytic effect of Cr2O3 lies in its high hardness, which has a significant cutting effect on alloy particles during ball milling, making the ball-milled alloy particles smaller.

[0040] This invention also discloses a method for preparing the above-mentioned Mg-Y-Al-Sn-based solid hydrogen storage composite material, the specific steps of which are as follows:

[0041] S1: Mg is composed according to the above chemical formula. 94-x Y x Al 6-y Sn yThe ingredients are prepared (the actual ingredients should be converted to mass based on the stoichiometric ratio). Mg, Y and Sn are added with a certain amount of loss on burn during the preparation process. The metal purity of the raw materials is ≥99.5%.

[0042] S2: The raw materials are melted under certain heating conditions by means of electric arc melting, induction heating melting or other heating methods, and the molten alloy is poured into a copper mold to obtain a master alloy ingot;

[0043] S3: Place the ingot prepared in step S2 into a quartz tube with a slit at the bottom, heat it by induction until the ingot is completely melted, and use the pressure of the protective gas to spray the liquid alloy from the slit at the bottom of the quartz tube onto the surface of the rotating water-cooled copper roller to form a fast-quenched alloy strip.

[0044] S4: The rapidly quenched alloy strip is mechanically crushed and passed through a 200-mesh sieve. The sieved alloy powder, along with a certain amount of catalyst (AlF3+Cr2O3) and stainless steel grinding balls, is loaded into a stainless steel ball mill jar and ball-milled to obtain a Mg-Y-Al-Sn based solid hydrogen storage alloy.

[0045] Specifically, since the metals Mg, Sn and rare earth Y have low melting points and are easily volatilized, a certain amount of ignition loss is added to the Mg, Y and Sn in step S1 during the formulation, which is 5%-10% by mass.

[0046] Specifically, the weighed bulk metal is placed in a magnesium oxide crucible within a medium-frequency induction furnace according to the designed process. Bulk rare earth elements (Y) and electrolytic Al are placed at the bottom of the crucible, metallic Sn is placed on top of the electrolytic Al, and bulk Mg is placed on the very top layer. This arrangement places components with lower content or those easily oxidized in the molten state in the middle and lower layers to reduce burn-off and oxidation; the main component with a higher melting point, Mg, is placed on the very top layer. This arrangement helps to increase the melting rate and improve the uniformity of the alloy.

[0047] Specifically, in step S2, the heating conditions are as follows: evacuation to 1×10⁻⁶. -2 -5×10 -5 A pressure of 0.01-0.1 MPa is introduced as a protective gas, which is high-purity helium or a helium-argon mixture with a volume ratio of approximately 1:1. The temperature is then increased to 1400-1550℃ to obtain molten Mg. 94-x Y x Al 6-y Sn y Liquid master alloy, hold for 1-5 minutes.

[0048] Specifically, in step S3, the linear speed of the water-cooled copper roller rotation is 10-30 m / s, for example, 13, 15, 18, 22, 25, 28 (m / s), and the thickness of the formed rapid quenching alloy strip is 50-150 μm, for example, 55, 65, 74, 86, 95, 105, 115, 125, 135, 145 (m / s), and the width is 2-30 mm, for example, 5, 10, 15, 20, 25 (mm). In this step, the thickness of the rapid quenching strip should be strictly controlled. An excessively thick strip can easily lead to the formation of micron-sized grains; an excessively thin strip can easily lead to the formation of amorphous states. The presence of both micron-sized crystals and amorphous states will affect the hydrogen absorption and desorption properties of the alloy. For example, when the quenching speed is 18 m / s and 22 m / s, the thickness of the rapid quenching strip is 86 μm and 74 μm, respectively, and the strip has a completely nanocrystalline structure, resulting in good hydrogen absorption and desorption thermodynamics and kinetics of the alloy. The width of the rapid quenching band does not have a direct impact on the alloy's properties.

[0049] Specifically, in step 3, melt quenching can produce a structure with ultrafine grains (grain size < 100 nm). This rapidly quenched structure contains a high density of crystal defects, including dislocations, stacking faults, twins, and numerous grain boundaries. This microstructure is extremely beneficial for improving the thermodynamic and kinetic properties of the alloy. Furthermore, unlike ball milling, the ultrafine structure and crystal defects obtained through rapid quenching exhibit high stability. After multiple hydrogen absorption and desorption cycles, the grains are less prone to aggregation and growth, resulting in excellent cycle stability in the alloy.

[0050] Specifically, in step S3, the slit width should be set appropriately to ensure that the liquid metal does not flow out of the slit without external force (i.e., its own weight) and can be smoothly ejected from the slit under appropriate external force (i.e., protective gas pressure). Generally, the pressure of the protective gas is about 0.5 MPa.

[0051] Specifically, in step S4, the ball milling process is as follows: after evacuating the ball mill jar, high-purity argon gas is introduced, and the ball mill is run in an all-around planetary high-energy ball mill for 3-5 hours with a ball-to-material ratio of 15-25:1 and a rotation speed of 300-500 rpm; during the ball milling process, the ball mill is stopped for 0.5 hours every hour of operation.

[0052] In step S4, using a suitable ball-to-material ratio and an appropriate rotation speed is to obtain the optimal ball milling efficiency; an appropriate ball milling time is to obtain particles with as many nanocrystalline particles as possible (e.g., ...). Figure 5 (As shown). Hydrogen absorption and desorption performance is controlled by hydrogen atom diffusion. Grain boundaries provide excellent channels for hydrogen atom diffusion, and nanocrystalline structures have the highest grain boundary density, offering unique benefits for hydrogen atom diffusion. Too short a ball milling time will not achieve the required grain size, while too long a ball milling time will result in an amorphous structure. Stopping the machine during ball milling is to prevent overheating of the grinding balls and abrasive.

[0053] Adding two catalysts (AlF3 + Cr2O3) and ball milling for a short time improved the surface state of the alloy while maintaining its microstructure in the rapidly quenched state, leveraging the advantages of both preparation processes. During ball milling, the two catalysts were uniformly distributed within the alloy matrix, fully utilizing their combined catalytic effect to enhance the alloy's thermodynamic and kinetic properties of hydrogen absorption and desorption. The catalytic effect of AlF3 lies primarily in its low hardness and excellent stability, providing excellent lubrication during ball milling and effectively preventing abrasive particles from adhering to the inner wall of the milling jar. The catalytic effect of Cr2O3 stems from its high hardness, exhibiting a significant cutting effect on the alloy particles during ball milling, resulting in finer particles. The addition of these two highly stable catalysts, after ball milling, ensures uniform distribution among the alloy particles, inevitably forming numerous active interfaces between the alloy and catalysts. These interfaces provide excellent nucleation sites for hydride formation and decomposition. This invention employs a combination of rapid quenching, ball milling, and catalyst addition, which significantly improves the thermodynamics and kinetics of hydrogen absorption and desorption in the alloy (as shown in Table 2).

[0054] Examples and comparative examples:

[0055] The chemical composition and proportions of the specific embodiments and comparative examples are shown in Table 1, in parts by weight, where Mg 94-x Y x Al 6-y Sn y 100 copies.

[0056] Table 1. Chemical composition and proportions of specific embodiments and comparative examples.

[0057]

[0058] According to the chemical formulas of each embodiment, bulk metal Mg, rare earth metal Y, electrolytic Al, and Sn are selected. The metal purity is required to be ≥99.5%. After the selected bulk metal is polished to remove the surface oxide layer, it is weighed according to the chemical dosage ratio. Among them, the proportions of metal Mg and Sn are increased by 8%, and the proportion of rare earth Y is increased by 5% to compensate for the loss during smelting.

[0059] The weighed bulk metal is placed in a magnesium oxide crucible of a medium-frequency induction furnace according to the designed process. Bulk rare earth Y and electrolytic Al are placed at the bottom of the crucible, metallic Sn is placed on top of electrolytic Al, and bulk Mg is placed on the top layer. This arrangement places components with lower content or those that are easily oxidized in the molten state in the middle and lower layers to reduce burn-off and oxidation; the main component with a higher melting point, Mg, is placed on the top layer. This arrangement helps to increase the melting rate and improve the uniformity of the alloy.

[0060] Close the furnace lid and evacuate for approximately 30 minutes until the vacuum level reaches 5×10⁻⁶. -2 Above a pressure of Pa, high-purity helium protective gas is introduced until the pressure reaches -0.04 MPa. The power is adjusted to 5 kW, and the temperature is controlled at 650℃ to melt Mg and Sn metals. Then, the power is adjusted to 25 kW, and the temperature is controlled at 1550℃ to melt Y metal. The molten liquid metal is held at this temperature for 5 minutes to ensure homogenization. The homogenized liquid metal is then poured into a cylindrical copper mold with a diameter of 30 mm and a depth of 80 mm. After cooling under a helium protective atmosphere for 30 minutes, the mold is removed from the furnace to obtain a master alloy ingot.

[0061] Approximately 100 grams of as-cast alloy rods were placed in a quartz tube with a diameter of 35 mm and a slit at the bottom measuring 0.05 mm × 20 mm. The rods were heated to a molten state at a frequency of 245 kHz under a helium atmosphere with a heating power of 15 kW. The molten alloy was then sprayed onto the surface of a water-cooled copper roller with a surface linear velocity of 20 m / s at a helium pressure of 1.05 atm, resulting in a rapidly quenched alloy strip with a thickness of approximately 80 μm. The rapidly quenched alloy strip was mechanically crushed and passed through a 200-mesh sieve. 20 g of the sieved alloy powder, a corresponding amount of catalyst (AlF3 + Cr2O3) (weighed according to the specific embodiment), and 400 g of stainless steel grinding balls were mixed together and placed in a 250 ml stainless steel ball mill jar. The jar was then evacuated, filled with high-purity argon, and sealed. The mixture was ball-milled for 4 hours in an omnidirectional planetary high-energy ball mill. The ball mill was stopped for 0.5 hours after every 1 hour of continuous operation to obtain the final hydrogen storage composite powder.

[0062] The structure of the ball-milled powder was tested by XRD. The morphology and microstructure of the alloy particles before and after hydrogen absorption were observed by high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). 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 pressure was 3 MPa, and the hydrogen desorption was carried out at 260℃ and 1×10⁻⁴ MPa.

[0063] Figure 1 The tested thin strip is a rapidly quenched alloy strip with a thickness of approximately 80 μm. TEM observation revealed that the rapidly quenched alloy strip has a nanocrystalline structure with a small amount of amorphous structure.

[0064] Figure 2 The XRD patterns of alloys numbered 1-6 in their as-cast state show that alloying with Al and Sn resulted in the formation of various intermetallic compounds, including Mg. 12 Al 17 And Mg2Sn.

[0065] Figure 3The SEM images show the morphology of the ball-milled composite powders numbered 1-6. Observations revealed excellent particle dispersion after ball milling, with no obvious agglomeration. No catalyst (AlF3 + Cr2O3) was observed, suggesting it is uniformly distributed on the surface of the ball-milled alloy particles. Since AlF3 is very soft, it will not penetrate into the interior of the alloy particles during ball milling. However, Cr2O3 is very hard, and Cr2O3 ions are highly likely to penetrate into the interior of the ball-milled alloy particles during the process.

[0066] Figure 4 The XRD patterns of the ball-milled composite powders numbered 1-6 reveal that the ball-milled materials exhibit nanocrystalline and amorphous structural characteristics.

[0067] Figure 5 The HRTEM morphology of the ball-milled composite powders numbered 1-6 shows that the alloys have nanocrystalline and amorphous structures.

[0068] The hydrogen absorption and release capacity and kinetics of the composite powder in gaseous state were tested using a fully automated Sieverts instrument. The results are shown in Table 2.

[0069] Table 2 Hydrogen absorption / desorption kinetics and cycling stability of alloy powders with different compositions

[0070]

[0071] C max —Saturated hydrogen absorption capacity (wt.%) at an initial hydrogen pressure of 3 MPa and a temperature of 200 °C

[0072] — Hydrogen absorption rate (wt.%) within 5 minutes at an initial hydrogen pressure of 3 MPa and a temperature of 200°C.

[0073] —At an initial pressure of 1×10 -4 Hydrogen release (wt.%) over 20 minutes at MPa and 260℃.

[0074] The above results show that the ball-milled composite powder has high hydrogen absorption and desorption capacity and excellent kinetic properties, especially when x=2 and y=2, the hydrogen absorption and desorption performance is optimal. Compared with magnesium-based alloys produced by traditional processes, the patented alloy has a breakthrough improvement in hydrogen absorption and desorption performance.

[0075] Obviously, the hydrogen storage composite material of the present invention can fully meet the hydrogen capacity requirements of the fuel cell for the hydrogen supply system. Compared with similar alloys at home and abroad, the hydrogen storage performance of the hydrogen storage composite material disclosed in the present invention has been significantly improved.

[0076] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A Mg-Y-Al-Sn based solid-state hydrogen storage composite material, characterized in that: Its component ingredients are as follows in parts by mass: 100 parts of Mg 94-x Y x Al 6-y Sn y 2-6 parts of AlF3 and Cr2O3, and other unavoidable impurities; in the formula, x and y are atomic ratios, and 1≤x≤4, 0.5≤y≤3.

2. The Mg-Y-Al-Sn based solid state hydrogen storage composite of claim 1, wherein: Its component ingredients are 100 parts of Mg 94-x Y x Al 6-y Sn y , 3-5 parts of AlF3 and Cr2O3 and other unavoidable impurities; in the formula x and y are atomic ratios, and 2≤x≤3, 1≤y≤2.

3. The Mg-Y-Al-Sn based solid state hydrogen storage composite of claim 1, wherein: wherein x = 2, y = 2.

4. The Mg-Y-Al-Sn based solid state hydrogen storage composite of claim 1, wherein: wherein the content of AlF3 and Cr2O3 is 5 parts by mass.

5. The Mg-Y-Al-Sn based solid state hydrogen storage composite of claim 1, wherein: The mass ratio of AlF3 and Cr2O3 is 1:

1.

6. A method for preparing the Mg-Y-Al-Sn based solid-state hydrogen storage composite material according to any one of claims 1-5, characterized in that: comprising the following steps: S1: according to the formula Mg 94-x Y x Al 6-y Sn y The ingredients are prepared with a metal purity of the raw materials ≥ 99.5%. S2: melting the raw materials by arc melting, induction heating melting or other heating methods, and pouring the melted alloy into a copper mold to obtain a master alloy ingot; S3: placing the ingot prepared in step S2 into a quartz tube with a slit at the bottom, and inductively heating to completely melt the ingot, using the pressure of the protective gas to spray the liquid alloy from the slit at the bottom of the quartz tube onto the surface of a rotating water-cooled copper roller to form a rapidly quenched alloy thin strip; S4: mechanically crushing the rapidly quenched alloy thin strip and passing it through a 200 mesh sieve, then retaining the small particles under the sieve together with the catalyst AlF3+Cr2O3 and stainless steel balls in a ball mill jar, and obtaining a Mg-Y-Al-Sn-based solid-state hydrogen storage composite material after ball milling.

7. The method of claim 6, wherein: In step S1, the Mg, Y and Sn are additionally added with a burning loss of 5%-10% of the calculated mass of the ingredients.

8. The method of claim 6, wherein: In step S2, the melting operation includes the following steps: placing the weighed bulk metal into a magnesia crucible of the intermediate frequency induction furnace according to the designed process, placing the bulk rare earth Y and electrolytic Al at the bottom of the crucible, placing the metal Sn on the top of the electrolytic Al, and placing the bulk Mg on the top layer, vacuumizing to 1×10 -2 -5×10 -5 Pa, and introducing 0.01-0.1 MPa inert gas as the protective gas, the protective gas being high-purity helium or a mixture of helium and argon with a volume ratio of 1:1, and heating at a temperature of 1400-1550°C to obtain the molten Mg 94-x Y x Al 6-y Sn y liquid master alloy, and keeping the temperature for 1-5 minutes.

9. The method of claim 6, wherein: In step S3, the linear speed of the rotating water-cooled copper roller is 10-30 m / s, and the rapidly quenched alloy thin strip formed has a thickness of 50-150 μm and a width of 2-30 mm.

10. The method of claim 6, wherein: In step S4, the ball milling is carried out by: after the ball mill jar is evacuated, filling it with high-purity argon, ball milling in a full-planet high-energy ball mill for 3-5 hours, ball-to-material ratio of 15-25:1, rotation speed of 300-500 rpm; during the ball milling, the ball mill is stopped for 0.5 hour every 1 hour of operation.

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