High-entropy alloy magnesium-based composite hydrogen storage material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of hydrogen storage materials, and discloses a magnesium-based composite hydrogen storage material based on high-entropy alloy catalysis and a hydrogenation ball milling preparation method thereof. The material is prepared from magnesium powder and a high-entropy alloy in a hydrogen atmosphere through a hydrogenation ball milling method, the high-entropy alloy comprises at least five elements of Ti, Cr, V, Fe, Ni, Mn, Zr, Nb, Mo and Co, and the mass ratio of the high-entropy alloy is 5%-30%. The composite material obtained after ball milling comprises two crystal forms of beta-MgH2 and gamma-MgH2, the content of the gamma-MgH2 is 10%-30%, and transition metal hydrides such as Mg2FeH6 and Mg2CoH5 are formed. The material has the advantages of high hydrogen storage capacity, substantial reduction of the hydrogen desorption temperature, excellent hydrogen absorption and desorption dynamic performance, good cycle stability, and suitableness for the field of hydrogen energy storage and transportation.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen storage materials, and in particular to a high-entropy alloy-doped magnesium-based composite hydrogen storage material and a preparation method thereof by hydrogenation reaction ball milling. Background Art

[0002] Magnesium-based hydrogen storage materials (Mg / MgH2) have attracted much attention due to their high theoretical hydrogen storage capacity (7.6 wt.%) and low cost, but their practical application is limited by high dehydrogenation temperatures (≥300°C), slow hydrogen absorption and dehydrogenation kinetics, and poor cyclic stability. Magnesium hydride generally has two crystal structures, β-MgH2 and γ-MgH2. β-MgH2 is thermally stable, while γ-MgH2 is thermodynamically unstable. The predicted enthalpy of the γ-MgH2 (110) plane is 44.66 kJ / mol, while the predicted enthalpy of the same plane of β-MgH2 is 78.16 kJ / mol H2. When the system contains more γ-MgH2, the dehydrogenation temperature of the magnesium-based hydrogen storage material can be significantly reduced, but the preparation of γ-MgH2 is more difficult. In addition, in the existing technology, the thermodynamic performance of magnesium hydride in hydrogen absorption and desorption is often improved by adding transition metal catalysts (such as Ni, Fe, and Co) through ball milling or nano-processing. However, single metal catalysts are easily deactivated due to oxidation or agglomeration, and the nano-processing of magnesium hydride is complex, costly, and has poor stability.

[0003] High entropy alloys (HEAs) are composed of multiple member elements. Their unique "cocktail effect" and lattice distortion effect provide abundant active sites, and compounding with magnesium hydride can improve their hydrogen release performance. Existing patents CN 118308635A and CN113912006 A disclose methods for preparing hydrogen storage materials by ball milling high entropy alloys and MgH2. Existing patent CN114105090 A discloses a Mg-based composite material catalyzed by high entropy alloys in situ. However, both methods use traditional ball milling methods and are carried out under an inert atmosphere. They use magnesium hydride as the raw material, which is relatively expensive. In addition, the main phase composition is β-MgH2, which makes it difficult to improve the problem of high thermodynamic stability.

[0004] Although high-entropy alloys (HEAs) have shown potential in improving the performance of magnesium-based hydrogen storage materials, existing preparation methods and technologies still face challenges, such as the uniform dispersion of HEAs and magnesium-based materials, the regulation of hydrogenation reaction thermodynamics, and the simultaneous realization of hydrogenation and nano-scaling. Therefore, it is of great significance to develop a new type of magnesium-based composite material and its preparation method to overcome the limitations of existing technologies and achieve efficient composites of HEAs and magnesium-based hydrogen storage materials. Summary of the Invention

[0005] The purpose of the present invention is to address the above problems and provide a high entropy alloy magnesium-based hydrogen storage material based on hydrogenation reaction ball milling technology and its preparation method, which effectively solves the problems of high dehydrogenation temperature and slow hydrogen release kinetics of existing magnesium-based hydrogen storage materials.

[0006] Technical solution of the present invention:

[0007] The present invention provides a high entropy alloy magnesium-based composite hydrogen storage material, which is characterized in that the design principle of the TiCrVFeM alloy composition is as follows: δ is the average atomic radius, and its calculation formula is as follows (1), where n is the number of elements, c i is the atomic percentage of the i-th element, r i is the atomic radius of the ith element, is the average atomic radius as shown in (2). VEC is the valence electron concentration, which is calculated as shown in (3), where VEC i is the valence electron concentration of the i-th element, c i is the atomic percentage of the i-th element. When δ ≤ 6.5 and VEC < 6.87, the BCC phase is more likely to form and has higher hydrogen storage capacity at room temperature. This is because when δ ≤ 6.5, the atomic radius differences among the alloy components are smaller. Smaller size differences help reduce lattice distortion, thereby stabilizing the BCC structure. Lower VEC tends to stabilize the BCC structure because a lower electron concentration reduces the directionality of metallic bonds, favoring the formation of a more symmetric BCC structure.

[0008]

[0009] The present invention provides a high-entropy alloy magnesium-based composite hydrogen storage material, wherein the magnesium-based composite hydrogen storage material comprises MgH2, Mg and a high-entropy alloy TiCrVFeM(H), recorded as MgH2 / Mg / TiCrVFeM(H); wherein the MgH2 content is 70-95 wt.%, the Mg content does not exceed 5 wt.%, and the TiCrVFeM(H) content is 5-30 wt.%;

[0010] The chemical formula of TiCrVFeM is (Ti a Cr b V c ) 1-x-y Fe x M y , wherein M is one or more of Ni, Mn, Zr, Nb, Mo, and Co, a / b = 0.6 to 1.0, c is 0.3 to 0.6, x is 0.05 to 0.1, and y is 0.05 to 0.15.

[0011] In some preferred embodiments, the content of BCC phase (space group Im3m) in the structure of the high entropy alloy is ≥ 90 wt.%;

[0012] In some more preferred embodiments, the high entropy alloy has a hydrogen absorption capacity of 1.5 wt.% or more under a hydrogen pressure of 5 MPa.

[0013] In some preferred embodiments, the chemical formula of TiCrVFeM is selected from any one or a combination of at least two of the following: (Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Co 0.10 、(Ti 0.20 Cr 0.20 V 0.60 ) 0.88 Fe 0.07 Zr 0.05 、(Ti 0.26 Cr 0.44 V 0.30 ) 0.90 Fe 0.05 Ni 0.05 、(Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Ni 0.10 、(Ti 0.20 Cr 0.20 V 0.60 ) 0.85 Fe 0.10 Ni 0.05 、(Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Mn 0.10 、(Ti 0.20 Cr 0.20 V 0.60 ) 0.78 Fe 0.07 Nb 0.15 、(Ti 0.26 Cr 0.44 V 0.30 ) 0.90 Fe 0.05 Mo 0.05 、(Ti 0.30 Cr 0.30 V 0.40 ) 0.85 Fe 0.05 Co 0.10 、(Ti 0.20 Cr 0.20 V 0.60 ) 0.75 Fe0.10 Mo 0.15 .

[0014] In some preferred embodiments, the MgH2 comprises two phase structures β-MgH2 and γ-MgH2, wherein the content of γ-MgH2 is 10-30 wt.%, preferably 20-30 wt.%, for example 13 wt.%, 15 wt.%, 17 wt.%, 19 wt.%, 20 wt.%, 22 wt.%, 23 wt.%, 25 wt.%, 26 wt.%, 27 wt.%, 28 wt.%, 29 wt.% or 30 wt.%.

[0015] In some preferred embodiments, the particle size of the magnesium-based composite hydrogen storage material is 50 to 300 nm, for example, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 120 nm, 150 nm, 200 nm, 250 nm, 300 nm; preferably, the particle size is obtained by wet testing using a laser particle size analyzer.

[0016] In some preferred embodiments, the magnesium-based composite hydrogen storage material further contains any one or a combination of at least two of the following: Mg2FeH6, Mg2CoH5, Mg2NiH6; preferably a combination of Mg2FeH6 and Mg2CoH5 and / or Mg2NiH6.

[0017] In some preferred embodiments, the magnesium-based composite hydrogen storage material further contains Mg2FeH6;

[0018] In some preferred embodiments, the magnesium-based composite hydrogen storage material further contains a combination of Mg2FeH6 and Mg2CoH5, a combination of Mg2FeH6 and Mg2NiH6, or a combination of Mg2FeH6, Mg2CoH5 and Mg2NiH6.

[0019] In some preferred embodiments, the hydrogen storage capacity of the magnesium-based composite hydrogen storage material is 6.5% to 7.5%.

[0020] In some preferred embodiments, the initial hydrogen desorption temperature of the magnesium-based composite hydrogen storage material is ≤210°C, for example, 180°C, 182°C, 185°C, 187°C, 190°C, 192°C, 195°C, 198°C, 200°C, 202°C, 204°C, 206°C, 208°C or 210°C.

[0021] In some preferred embodiments, the amount of hydrogen released by the magnesium-based composite hydrogen storage material within 80 minutes at 260°C is 4.00wt.% to 6.00wt.%; for example, 4.20wt.%, 4.39wt.%, 4.50wt.%, 4.70wt.%, 4.87wt.%, 5.00wt.%, 5.09wt.%, 5.17wt.%, 5.20wt.%, 5.27wt.%, 5.38wt.%, 5.40wt.%, 5.50wt.%, 5.57wt.%, 5.60wt.%, 5.70wt.%, 5.80wt.% or 5.10wt.%.

[0022] The present invention also provides a method for preparing the high entropy alloy magnesium-based composite hydrogen storage material, comprising the following steps:

[0023] (1) Mixing magnesium powder and high entropy alloy powder in a mass ratio of (70-95): (5-30), placing the mixed powder in a stainless steel ball mill, filling it with 1-2 MPa protective gas, sealing it, and placing it in a planetary ball mill at a speed of 800-1200 rpm for premixing for 1-4 hours; preferably, the protective gas includes argon;

[0024] (2) hydrogen is filled into a ball mill to a pressure of 3 to 6 MPa, stainless steel grinding balls with a diameter of 3 to 14 mm are added, the ball-to-material ratio is 40:1 to 120:1, the rotation speed is 800 to 1200 rpm, and hydrogenation ball milling is performed for 4 to 12 hours to obtain the magnesium-based composite hydrogen storage material; preferably, the particle size of the magnesium-based composite hydrogen storage material is 50 to 300 nm.

[0025] In some preferred embodiments, the particle size of the magnesium powder is 80-200 mesh, and the particle size of the high entropy alloy powder is 40-200 mesh.

[0026] In some preferred embodiments, the start-stop mode in the ball mill is to stop for 30 minutes every 2 hours of operation.

[0027] In some preferred embodiments, the TiCrVFeM alloy is prepared by conventional alloy preparation methods including suspension melting, arc melting, powder metallurgy, mechanical alloying, plasma melting, etc.

[0028] In a third aspect, the present invention also provides an application of the high entropy alloy magnesium-based composite hydrogen storage material in the field of hydrogen storage.

[0029] The technical effects of the present invention are at least:

[0030] (1) The present invention adopts hydrogenation reaction ball milling to achieve in-situ hydrogenation and nano-sizing of magnesium powder and its compounding with high entropy alloy in one step, thereby achieving uniform dispersion of high entropy alloy on its surface and directional generation of γ-MgH2. The process is simple and the cost is low.

[0031] (2) Through the multi-element synergistic effect of high-entropy alloys and the auxiliary grinding effect, transition metal hydrides (such as Mg2FeH6, etc.) and metastable γ-MgH2 phase are introduced into the MgH2 matrix to construct a three-in-one composite system of "hydrogen diffusion channel-catalytic active site-low thermal enthalpy phase". The high-entropy alloys inhibit the agglomeration of MgH2 particles and reduce the capacity decay during the cycle, ultimately achieving a breakthrough in the system's low-temperature hydrogen release (≤210℃), high kinetic performance and long cycle life.

[0032] (3) In addition, the unique high-entropy alloy composition designed in the present invention enables the alloy to have both a BCC structure and a high hydrogen storage capacity (1.2 to 3.3 wt.%), thereby reducing the problem of reduced hydrogen storage capacity of composite magnesium-based hydrogen storage materials due to the addition of catalysts, and further improving the overall hydrogen storage performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Example 1 Transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS) distribution maps of each element.

[0034] Figure 2 Laser particle size test results of Example 1 and Comparative Examples 1 and 2.

[0035] Figure 3 XRD patterns of Example 1 and Comparative Examples 1 and 2.

[0036] Figure 4 Differential scanning calorimetry (DSC) curves of Example 1 and Comparative Examples 1 and 2.

[0037] Figure 5 Hydrogen release kinetic curves of Example 1 and Comparative Examples 1 and 2 at 260°C.

[0038] Figure 6 Hydrogen release kinetic curves of Example 1 and Comparative Examples 1 and 2 at 300°C.

[0039] Figure 7 50-week hydrogen absorption and desorption cycle curve of Example 1. DETAILED DESCRIPTION

[0040] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments shown below do not limit the invention as described in the claims. In addition, the entire contents of the structures shown in the following embodiments are not limited to those necessary for the solution of the invention as described in the claims.

[0041] Example 1

[0042] Preparation of high entropy alloys:

[0043] Based on the principle of δ ≤ 6.5 and VEC < 6.87, high-entropy alloys (numbers 1 to 10) were designed. As shown in Table 1, pure metal raw materials with a purity of at least 99.5 wt.% were formulated according to the molecular formula. Cast alloy ingots were prepared by arc melting under an argon atmosphere. Mechanical crushing under argon was then performed to obtain -100 mesh alloy powder. Their hydrogen absorption properties were tested under a hydrogen pressure of 5 MPa, and the resulting hydrogen storage capacities are listed in Table 1.

[0044] Table 1 Average atomic radius, valence electron concentration and hydrogen absorption capacity of high entropy alloys

[0045]

[0046] Preparation of high entropy alloy magnesium-based composite hydrogen storage materials:

[0047] Mix the -200 mesh Mg powder with the -100 mesh No. 1 (Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Co 0.1 High-entropy alloy powder was placed in a sealed stainless steel ball mill at a stoichiometric ratio of 90:10 and filled with 1 MPa argon. Premixed for 2 hours using a planetary ball mill at 800 rpm was then added to the mill, achieving a ball-to-powder ratio of 80:1. Hydrogen was then introduced at 5 MPa for 6 hours, followed by a 30-minute pause every 2 hours, to produce a high-entropy alloy magnesium-based composite hydrogen storage material.

[0048] Comparative Example 1

[0049] The -200 mesh Mg powder was placed in a sealed stainless steel ball mill, 10 mm stainless steel grinding balls were added, the ball-to-material ratio was 80:1, 5 MPa hydrogen was filled, and hydrogen ball milling was performed for 6 hours, with a 30 minute stop every 2 hours to obtain magnesium hydride hydrogen storage material.

[0050] Comparative Example 2

[0051] On the basis of Example 1, the (Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Co 0.1 High entropy alloy is replaced by the molecular formula Ti 0.32 Cr 0.30 V 0.38 The other steps are the same as those in Example 1.

[0052] Ti 0.32 Cr 0.30 V 0.38The preparation method of alloy powder is as follows: pure metal raw material with purity not less than 99.5wt.% is prepared according to the molecular formula Ti 0.32 Cr 0.30 V 0.38 The materials are prepared, arc melting is performed under argon protection atmosphere to obtain a cast alloy ingot, and mechanical powdering is performed under argon protection to obtain -100 mesh alloy powder.

[0053] Structure and performance testing:

[0054] (1) Take a small amount of the high entropy alloy composite magnesium-based hydrogen storage material of Example 1 and perform high-resolution transmission electron microscopy testing. Figure 1 ) can be observed on (Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Co 0.1 The alloy particles are evenly and dispersedly distributed on the MgH2 alloy matrix.

[0055] (2) Laser particle size analysis was performed on the obtained high-entropy alloy composite magnesium-based hydrogen storage material. The average particle sizes obtained for Example 1 and Comparative Examples 1 and 2 were 78 nm, 255 nm, and 220 nm, respectively. This indicates that the magnesium-based hydrogen storage material with the addition of a high-entropy alloy has a smaller average particle size, which is beneficial to improving its hydrogen absorption and desorption kinetics and thermodynamics.

[0056] (3) X-ray powder diffraction test ( Figure 3 ), using Cu Kα radiation, power 40kV×150mA, step scanning, step size of 0.02°, 2θ range of 10°~90°, and the obtained XRD data were subjected to Rietveld refinement using GSAS software to obtain the phase composition of the alloy. Figure 2 The XRD spectra of the materials of Example 1 and Comparative Examples 1 and 2. The diffraction peak intensity of the composite magnesium-based hydrogen storage material with the addition of high entropy alloy is lower and the half-peak width is wider, indicating that the particle size of the material is significantly reduced. The unit cell parameters of Example 1 and Comparative Examples 1 and 2 obtained by Rietveld refinement are listed in Table 2. Among them, the FCC phase with the space group Fm / 3m is the high entropy alloy TiCrVFeMH after hydrogenation, and the BCC phase with the space group Im3m is the unhydrogenated high entropy alloy TiCrVFeM. It can be seen from the figure that Example 1 and Comparative Examples 1 and 2 all produce β-MgH2 and γ-MgH2 phases. However, the content of γ-MgH2 phase in the embodiment is higher, which can effectively reduce the hydrogen desorption temperature of the composite material.

[0057] Table 2 Rietveld refinement results of Example 1 and Comparative Examples 1 and 2

[0058]

[0059] (4) Differential scanning calorimetry (DSC) was used to test the dehydrogenation temperature. High-purity argon was used as the protective gas and purge gas. The heating rate was set to 10°C / min and the temperature range was set to 30°C to 450°C. The test results are as follows: Figure 4 Compared with the initial hydrogen desorption temperature of 324°C in Comparative Example 1 and the initial hydrogen desorption temperature of 228°C in Comparative Example 2, the initial hydrogen desorption temperature of Example 1 is reduced to 193°C.

[0060] The DSC test results are consistent with the unit cell parameter results obtained by Rietveld refinement. The γ-MgH2 phase content in Example 1 is 24.0wt.%, and the γ-MgH2 phase contents in Comparative Example 1 and Comparative Example 2 are 3.2wt.% and 6.4wt.%, respectively; the γ-MgH2 phase content is increased by about 18wt.% to 21wt.%; the dehydrogenation temperature is reduced by 131°C and 35°C compared with Comparative Examples 1 and 2, respectively, and the dehydrogenation temperature reduction effect is significant.

[0061] (5) The hydrogen desorption kinetics test requires the entire system to be evacuated to 0.001 MPa, and then the sample tank is heated to the test temperature. After the temperature stabilizes, the hydrogen desorption kinetics performance is tested. The hydrogen desorption amount of Comparative Example 1 at 260°C for 80 minutes is only 0.20 wt.%, and the hydrogen desorption amount at 300°C for 80 minutes is 1.88 wt.%. In comparison, Figure 5 and Figure 6 Comparative Example 2 exhibited a hydrogen desorption capacity of 3.72 wt.% over 80 minutes at 260°C and 6.53 wt.% over 40 minutes at 300°C. Therefore, the addition of the alloy significantly improved the hydrogen desorption kinetics of the composite material. Compared to Comparative Example 2, Example 1 exhibited a hydrogen desorption capacity of 5.27 wt.% over 80 minutes at 260°C and 6.79 wt.% over 40 minutes at 300°C, demonstrating significant increases in both hydrogen desorption capacity and rate.

[0062] (6) The cyclic stability test was carried out at 280°C. First, the hydrogen desorption kinetics performance test was carried out at a pressure of 0.001MPa. After the hydrogen desorption test was completed, the system pipeline volume and the sample tank were vacuumed. Subsequently, a pressure of 1MPa was applied to the system, and the hydrogen absorption kinetics curve was tested at a temperature of 280°C, thus completing the first hydrogen absorption / desorption cycle. This operation process was repeated in sequence, and finally 50 hydrogen absorption / desorption cycle tests were completed (the results are shown in Figure 7Over 50 cycles of hydrogen absorption and desorption, the composite material's hydrogen absorption capacity remained essentially stable, maintaining between 6.50wt.% and 6.60wt.%. In contrast, the dehydrogenation capacity primarily declined during the second cycle, dropping from an initial 6.53wt.% to 5.97wt.%, before stabilizing over subsequent cycles. The calculated capacity retention for the first 50 cycles was 91.4%.

[0063] Example 2

[0064] -200 mesh Mg powder and -100 mesh (Ti 0.20 Cr 0.20 V 0.60 ) 0.88 Fe 0.07 Zr 0.05 The alloy powder and the mixture were placed in a sealed stainless steel ball mill at a stoichiometric ratio of 90:10 and filled with 1 MPa argon. The mixture was pre-mixed for 2 hours using a planetary ball mill at 800 rpm. 10 mm stainless steel grinding balls were then added to the mill, achieving a ball-to-material ratio of 80:1. The mill was then filled with 5 MPa hydrogen and subjected to hydrogen milling for 6 hours, with a 30-minute pause every 2 hours. This resulted in a high-entropy magnesium alloy composite hydrogen storage material.

[0065] The phase composition determined by the above method is β-MgH2, γ-MgH2, Mg2FeH6, BCC, FCC, and C14 Laves phases. The γ-MgH2 phase content is 26.0 wt.%. The initial dehydrogenation temperature is reduced to 198°C, and the hydrogen release rate within 80 minutes at 260°C is 5.38 wt.%. The capacity retention over the first 50 weeks is 90.0%.

[0066] Comparative Example 3

[0067] The purchased MgH2 powder (15-25 microns) was mixed with the (Ti 0.2 0Cr 0.20 V 0.60 ) 0.88 Fe 0.07 Zr 0.05 The high-entropy alloy was ball-milled in a sealed stainless steel milling jar at a stoichiometric ratio of 90:10, protected by 1 MPa argon gas. Premixing was performed at 800 rpm for 2 hours using a planetary ball mill. 10 mm stainless steel grinding balls were then added to the mill, achieving a ball-to-material ratio of 80:1. Hydrogen was then introduced at 1 MPa and milled for 6 hours, with 30-minute pauses every 2 hours, to produce a high-entropy alloy magnesium-based composite hydrogen storage material.

[0068] The material obtained by the above method has a phase composition of β-MgH2, BCC, and C14 Laves phase, without γ-MgH2 phase. The initial hydrogen desorption temperature is 242°C, and the hydrogen desorption rate within 80 minutes at 260°C is 3.24 wt.%.

[0069] Table 3 Hydrogen storage performance of magnesium-based hydrogen storage materials prepared from different raw materials

[0070]

[0071]

[0072] It can be seen from the above-mentioned Example 2 and Comparative Example 3 that Example 2 uses Mg powder as raw material and adopts ball milling for in-situ hydrogenation under high-pressure hydrogen conditions; Comparative Example 3 uses the same high-entropy alloy and MgH2 powder as raw material, and directly adopts ball milling to prepare hydrogen storage material. The finished composite hydrogen storage material does not contain γ-MgH2 phase, resulting in a significant increase in the initial hydrogen desorption temperature compared with Example 2, with a difference of nearly 50°C; and the hydrogen desorption amount within 80 minutes at 260°C in Comparative Example 3 also shows a decreasing trend.

[0073] Example 3

[0074] Mg powder smaller than 200 mesh and -100 mesh (Ti 0.26 Cr 0.44 V 0.30 ) 0.90 Fe 0.05 Ni 0.05 The alloy powder and the mixture were placed in a sealed stainless steel ball mill at a stoichiometric ratio of 90:10 and filled with 1 MPa argon. The mixture was pre-mixed for 2 hours using a planetary ball mill at 800 rpm. 10 mm stainless steel grinding balls were then added to the mill, achieving a ball-to-material ratio of 80:1. The mill was then filled with 5 MPa hydrogen and subjected to hydrogen milling for 6 hours, with a 30-minute pause every 2 hours. This resulted in a high-entropy magnesium alloy composite hydrogen storage material.

[0075] The phase composition determined by the above method is β-MgH2, γ-MgH2, Mg2NiH4, Mg2FeH6, BCC, and FCC phases. The γ-MgH2 phase content is 15 wt.%. The initial dehydrogenation temperature is reduced to 208°C, and the hydrogen release rate within 80 minutes at 260°C is 4.39 wt.%. The capacity retention over the first 50 weeks is 93.3%.

[0076] Example 4

[0077] Mg powder smaller than 200 mesh and -100 mesh (Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Ni0.10 The alloy powder and the stoichiometric ratio of 90:10 were placed in a sealed stainless steel ball mill jar, and 1 MPa of argon was filled. A planetary ball mill was used for pre-mixing at 800 rpm for 2 h. Then 10 mm stainless steel balls were added to the ball mill jar, with a ball-to-material ratio of 80:1, 5 MPa of hydrogen was filled, and hydrogenation ball milling was performed for 6 hours, with a 30 min stop every 2 h, to obtain the high-entropy alloy magnesium-based composite hydrogen storage material.

[0078] The phase composition obtained by testing according to the above method was β-MgH2, γ-MgH2, Mg2NiH4, Mg2FeH6, BCC, and FCC phases. The γ-MgH2phase content was 20.6 wt.%, the initial hydrogen release temperature was reduced to 204°C, the hydrogen release amount at 260°C within 80 min was 4.87 wt.%, and the capacity retention rate in the first 50 cycles was 94.6%.

[0079] Example 5

[0080] The Mg powder less than 200 mesh was mixed with -100 mesh (Ti 0.20 Cr 0.20 V 0.60 ) 0.85 Fe 0.10 Ni 0.05 The alloy powder and the stoichiometric ratio of 90:10 were placed in a sealed stainless steel ball mill jar, and 1 MPa of argon was filled. A planetary ball mill was used for pre-mixing at 800 rpm for 2 h. Then 10 mm stainless steel balls were added to the ball mill jar, with a ball-to-material ratio of 80:1, 5 MPa of hydrogen was filled, and hydrogenation ball milling was performed for 6 hours, with a 30 min stop every 2 h, to obtain the high-entropy alloy magnesium-based composite hydrogen storage material.

[0081] The phase composition obtained by testing according to the above method was β-MgH2, γ-MgH2, Mg2NiH4, Mg2FeH6, BCC, and FCC phases. The γ-MgH2phase content was 20.6 wt.%, the initial hydrogen release temperature was reduced to 204°C, the hydrogen release amount at 260°C within 80 min was 4.87 wt.%, and the capacity retention rate in the first 50 cycles was 94.6%.

[0082] Example 6

[0083] The Mg powder less than 200 mesh was mixed with -100 mesh (Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Mn 0.10The alloy powder and the Mg powder in a stoichiometric ratio of 90:10 were placed in a sealed stainless steel ball mill jar and filled with 1 MPa argon. A planetary ball mill was used for pre-mixing at a speed of 800 rpm for 2 h. Then 10 mm stainless steel balls were added to the jar with a ball-to-powder ratio of 80:1, and 5 MPa hydrogen was filled for hydrogenation ball milling for 6 h with 30 min stop every 2 h. A high-entropy alloy Mg-based composite hydrogen storage material was obtained.

[0084] The phase composition of the obtained sample was β-MgH2, γ-MgH2, BCC, FCC, and Mg2FeH6. The content of the γ-MgH2 phase was 22.1 wt.%, the initial hydrogen release temperature was reduced to 202°C, the hydrogen release amount was 5.09 wt.% within 80 min at 260°C, and the capacity retention rate was 91.5% in the first 50 cycles.

[0085] Example 7

[0086] The Mg powder less than 200 mesh was mixed with the -100 mesh (Ti 0.20 Cr 0.20 V 0.60 ) 0.78 Fe 0.07 Nb 0.15 The alloy powder and the Mg powder in a stoichiometric ratio of 90:10 were placed in a sealed stainless steel ball mill jar and filled with 1 MPa argon. A planetary ball mill was used for pre-mixing at a speed of 800 rpm for 2 h. Then 10 mm stainless steel balls were added to the jar with a ball-to-powder ratio of 80:1, and 5 MPa hydrogen was filled for hydrogenation ball milling for 6 h with 30 min stop every 2 h. A high-entropy alloy Mg-based composite hydrogen storage material was obtained.

[0087] The phase composition of the obtained sample was β-MgH2, γ-MgH2, BCC, FCC, and Mg2FeH6. The content of the γ-MgH2 phase was 22.1 wt.%, the initial hydrogen release temperature was reduced to 202°C, the hydrogen release amount was 5.09 wt.% within 80 min at 260°C, and the capacity retention rate was 91.5% in the first 50 cycles.

[0088] Example 8

[0089] The Mg powder less than 200 mesh was mixed with the -100 mesh (Ti 0.26 Cr 0.44 V 0.30 ) 0.90 Fe 0.05 Mo 0.05The alloy powder and the stoichiometric ratio of 90:10 were placed in a sealed stainless steel ball mill jar, and 1 MPa of argon was filled. A planetary ball mill was used for pre-mixing at 800 rpm for 2 h. Then 10 mm stainless steel balls were added to the ball mill jar, with a ball-to-material ratio of 80:1, and 5 MPa of hydrogen was filled for hydrogenation ball milling for 6 hours, with a 30 min stop every 2 h. A high-entropy alloy magnesium-based composite hydrogen storage material was obtained.

[0090] The phase composition obtained by testing according to the above method was β-MgH2, γ-MgH2, BCC, FCC, Mg2CoH5, and Mg2FeH6. The content of the γ-MgH2 phase was 26.8 wt.%, the initial hydrogen release temperature was reduced to 185°C, the hydrogen release amount at 260°C within 80 min was 5.57 wt.%, and the capacity retention rate in the first 50 cycles was 93.5%.

[0091] Example 9

[0092] The Mg powder less than 200 mesh was mixed with -100 mesh (Ti 0.30 Cr 0.30 V 0.40 ) 0.85 Fe 0.05 Co 0.10 The alloy powder and the stoichiometric ratio of 90:10 were placed in a sealed stainless steel ball mill jar, and 1 MPa of argon was filled. A planetary ball mill was used for pre-mixing at 800 rpm for 2 h. Then 10 mm stainless steel balls were added to the ball mill jar, with a ball-to-material ratio of 80:1, and 5 MPa of hydrogen was filled for hydrogenation ball milling for 6 hours, with a 30 min stop every 2 h. A high-entropy alloy magnesium-based composite hydrogen storage material was obtained.

[0093] The phase composition obtained by testing according to the above method was β-MgH2, γ-MgH2, BCC, FCC, Mg2CoH5, and Mg2FeH6. The content of the γ-MgH2 phase was 26.8 wt.%, the initial hydrogen release temperature was reduced to 185°C, the hydrogen release amount at 260°C within 80 min was 5.57 wt.%, and the capacity retention rate in the first 50 cycles was 93.5%.

[0094] Example 10

[0095] The Mg powder less than 200 mesh was mixed with -100 mesh (Ti 0.20 Cr 0.20 V 0.60 ) 0.75 Fe 0.10 Mo 0.15The alloy powder and 90:10 stoichiometric ratio were placed in a sealed stainless steel ball mill jar and filled with 1 MPa argon. A planetary ball mill was used to pre-mix for 2 h at 800 rpm. Then 10 mm stainless steel balls were added to the jar at a ball to powder ratio of 80:1 and 5 MPa hydrogen was filled. Hydrogenation ball milling was performed for 6 h with 30 min stop every 2 h to obtain the high-entropy alloy magnesium-based composite hydrogen storage material.

[0096] The phase composition of the obtained material was β-MgH2, γ-MgH2, BCC, FCC and Mg2FeH6. The content of γ-MgH2 phase was 23.9 wt.%, the initial dehydrogenation temperature was reduced to 192 °C, the dehydrogenation amount at 260 °C within 80 min was 5.10 wt.%, and the capacity retention rate of the first 50 cycles was 90.5%.

[0097] Table 4 Hydrogen storage properties of magnesium-based hydrogen storage materials prepared from different high-entropy alloys

[0098]

[0099]

[0100] The above description of disclosed embodiments enables one of ordinary skill in the art to make and use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be 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 high entropy alloy magnesium-based composite hydrogen storage material, characterized in that: The magnesium-based composite hydrogen storage material comprises MgH2, Mg and high entropy alloy TiCrVFeM(H); wherein the MgH2 content is 70-95 wt.%, the Mg content does not exceed 5 wt.%, and the TiCrVFeM(H) content is 5-30 wt.%; The chemical formula of TiCrVFeM is (Ti a Cr b V c ) 1-x-y Fe x M y , wherein M is one or more of Ni, Mn, Zr, Nb, Mo, and Co, a / b = 0.6 to 1.0, c is 0.3 to 0.6, x is 0.05 to 0.1, and y is 0.05 to 0.

15.

2. The high entropy alloy magnesium-based composite hydrogen storage material according to claim 1, characterized in that: The content of BCC phase (space group Im3m) in the structure of the high entropy alloy is ≥90wt.%; Preferably, the high entropy alloy has a hydrogen absorption capacity of 1.5 wt.% or more under a hydrogen pressure of 5 MPa.

3. The high entropy alloy magnesium-based composite hydrogen storage material according to claim 1 or 2, characterized in that: The chemical formula of TiCrVFeM is selected from any one or a combination of at least two of the following: (Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Co 0.10 、(Ti 0.20 Cr 0.20 V 0.60 ) 0.88 Fe 0.07 Zr 0.05 、(Ti 0.26 Cr 0.44 V 0.30 ) 0.90 Fe 0.05 Ni 0.05 、(Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Ni 0.10 、(Ti 0.20 Cr 0.20 V 0.60 ) 0.85 Fe 0.10 Ni 0.05 、(Ti 0.32 Cr 0.30 V 0.38 ) 0.83 Fe 0.07 Mn 0.10 、(Ti 0.20 Cr 0.20 V 0.60 ) 0.78 Fe 0.07 Nb 0.15 、(Ti 0.26 Cr 0.44 V 0.30 ) 0.90 Fe 0.05 Mo 0.05 、(Ti 0.30 Cr 0.30 V 0.40 ) 0.85 Fe 0.05 Co 0.10 、(Ti 0.20 Cr 0.20 V 0.60 ) 0.75 Fe 0.10 Mo 0.15 .

4. The high entropy alloy magnesium-based composite hydrogen storage material according to claim 1, characterized in that: The MgH2 comprises two phase structures, β-MgH2 and γ-MgH2, wherein the content of γ-MgH2 is 10 to 30 wt.%, preferably 20 to 30 wt.%.

5. The high entropy alloy magnesium-based composite hydrogen storage material according to claim 1, characterized in that: The particle size of the magnesium-based composite hydrogen storage material is 50-300 nm.

6. The high entropy alloy magnesium-based composite hydrogen storage material according to claim 1, characterized in that: The magnesium-based composite hydrogen storage material further contains Mg2FeH6; preferably, contains a combination of Mg2FeH6 and Mg2CoH5 and / or Mg2NiH6.

7. The high entropy alloy magnesium-based composite hydrogen storage material according to any one of claims 1 to 6, characterized in that: The hydrogen storage capacity of the magnesium-based composite hydrogen storage material is 6.5% to 7.5%, and the initial hydrogen release temperature is ≤210°C.

8. A method for preparing the high entropy alloy magnesium-based composite hydrogen storage material according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Mixing magnesium powder and high entropy alloy powder in a mass ratio of (70-95): (5-30), placing the mixed powder in a stainless steel ball mill, filling it with 1-2 MPa protective gas, sealing it, and placing it in a planetary ball mill at a speed of 800-1200 rpm for premixing for 1-4 hours; preferably, the protective gas includes argon; (2) hydrogen is filled into a ball mill to a pressure of 3 to 6 MPa, stainless steel grinding balls with a diameter of 3 to 14 mm are added, the ball-to-material ratio is 40:1 to 120:1, the rotation speed is 800 to 1200 rpm, and hydrogenation ball milling is performed for 4 to 12 hours to obtain the magnesium-based composite hydrogen storage material; preferably, the particle size of the magnesium-based composite hydrogen storage material is 50 to 300 nm.

9. The method for preparing a high entropy alloy magnesium-based composite hydrogen storage material according to claim 8, characterized in that: The particle size of the magnesium powder is 80-200 meshes, and the particle size of the high entropy alloy powder is 40-200 meshes.

10. Use of the high entropy alloy magnesium-based composite hydrogen storage material according to any one of claims 1 to 7 in the field of hydrogen storage.

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