Hydrogen storage alloy composite modified magnesium-based hydrogen storage material and preparation method and application thereof

Abstract

This invention provides a magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite, its preparation method, and its application. The magnesium-based hydrogen storage material comprises a body-centered cubic hydrogen storage alloy and a MgH2 composite. The magnesium-based hydrogen storage material provided by this invention combines a body-centered cubic hydrogen storage alloy with MgH2, effectively reducing the dehydrogenation temperature of the magnesium-based hydrogen storage material, improving its hydrogen absorption and desorption kinetics, and achieving rapid hydrogen absorption and desorption. Simultaneously, it overcomes the defect in existing technologies where catalyst composite modification leads to a decrease in the hydrogen storage capacity of magnesium-based hydrogen storage materials. The preparation process is simple and has good application prospects.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage materials technology, and relates to a magnesium-based hydrogen storage material, and more particularly to a magnesium-based hydrogen storage material modified with a hydrogen storage alloy, its preparation method and application. Background Technology

[0002] Hydrogen energy, as a secondary clean energy source, boasts advantages such as high energy density, abundant sources, and no polluting byproducts, making it an ideal alternative to fossil fuels. However, achieving safe, efficient, high-density, and reversible hydrogen storage remains a key technological constraint on the long-term development of the hydrogen energy industry. Current research and development focuses on high-pressure gaseous hydrogen storage, liquid hydrogen storage, and low-pressure solid-state hydrogen storage. Compared to high-pressure gaseous and cryogenic liquid hydrogen storage, low-pressure solid-state hydrogen storage offers higher safety, higher volumetric hydrogen storage density, and lower storage costs, making it a promising storage and transportation method for the future development of the hydrogen energy industry. Currently, among solid-state hydrogen storage materials, the capacity of AB5, AB2, AB, and V-based solid solution BCC hydrogen storage alloys is <3.8wt%, making it difficult to further break through theoretical hydrogen storage capacity limits. In contrast, the lightweight metal hydride MgH2 has a high mass hydrogen storage density of 7.6wt%, making it the most promising candidate to achieve the lightweight vehicle-mounted hydrogen storage capacity target (5.5wt%). Furthermore, magnesium metal offers significant advantages such as abundant resources, low price, and simple preparation, demonstrating broad application prospects. However, the current hydrogen absorption and desorption rate of MgH2 is slow, and the dehydrogenation temperature is even as high as 300℃ or more, which presents a high kinetic energy barrier. Moreover, its thermodynamic properties are relatively stable, and the enthalpy change of the dehydrogenation reaction is as high as 76kJ / mol, which seriously limits its practical application and makes it difficult to meet the actual needs of hydrogen addition and supply rates of actual hydrogen storage devices, thus limiting its large-scale industrial application.

[0003] Currently, researchers often improve the hydrogen absorption and desorption performance of magnesium-based hydrogen storage materials through doping, alloying, or nano-sizing. For example, patents CN115784147A, CN115159459A, and CN115403008A disclose methods to improve the hydrogen absorption and desorption kinetics of MgH2 and enhance its hydrogen storage performance by doping a catalyst with MgH2 to form a composite hydrogen storage material. CN113830729A discloses a Fe-doped MgH2 solid solution hydrogen storage material and its preparation method, which involves doping MgH2 hydrogen storage material with nano-iron powder, causing lattice distortion of MgH2 and weakening the Mg-H bond effect, thereby improving the thermodynamics and kinetics of the hydrogen release process of MgH2.

[0004] In existing research, composite materials of MgH2 by doping with multi-component, multi-valent metal catalysts can effectively reduce the kinetic energy barrier of MgH2. However, since the catalyst itself does not have hydrogen storage performance, the high doping content limits the further improvement of the hydrogen storage capacity of MgH2. Summary of the Invention

[0005] The purpose of this invention is to provide a magnesium-based hydrogen storage material modified by a hydrogen storage alloy, its preparation method and application. By combining different hydrogen storage materials at the nanoscale, the performance advantages of various hydrogen storage materials are brought into play, the performance shortcomings of single hydrogen storage materials are made up for, and the hydrogen absorption and desorption kinetics of magnesium-based hydrogen storage materials are improved.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a magnesium-based hydrogen storage material modified by a hydrogen storage alloy composite, wherein the magnesium-based hydrogen storage material comprises a body-centered cubic hydrogen storage alloy and a MgH2 composite.

[0008] The magnesium-based hydrogen storage material provided by this invention combines a body-centered cubic hydrogen storage alloy with MgH2 material at the nanoscale. The hydrogen storage alloy and MgH2 form a high-density interface including phase boundaries and grain boundaries. After ball milling and combining with MgH2, a large number of hydrogen diffusion channels are provided, which further accelerates the dissociation and recombination of hydrogen molecules, effectively reduces the dehydrogenation temperature, improves kinetic performance, and achieves a rapid hydrogen absorption and desorption rate, thus improving the hydrogen storage performance of the magnesium-based hydrogen storage material. At the same time, the hydrogen storage alloy itself has good hydrogen storage capacity and performance, overcoming the problem of reduced hydrogen storage capacity caused by using catalysts without hydrogen storage performance to modify MgH2 in the prior art.

[0009] Preferably, the body-centered cubic hydrogen storage alloy accounts for 2-30 wt% of the magnesium-based hydrogen storage material, for example, 2 wt%, 5 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt%, 15 wt%, 16 wt%, 18 wt%, 20 wt%, 25 wt%, or 30 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 5-20 wt%.

[0010] Preferably, the body-centered cubic hydrogen storage alloy comprises Ti a Cr b M x Where 35≤a≤55, 35≤b≤55, 5≤x≤20, and M includes any one or at least a combination of two of Nb, V, or Mo.

[0011] Where 'a' is 35-55, for example, it can be 35, 40, 45, 50 or 55, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0012] b is 35-55, for example, it can be 35, 40, 45, 50 or 55, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] x is between 5 and 20, for example, it can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] M includes any one or at least two combinations of Nb, V, or Mo. Typical but non-limiting combinations include combinations of Nb and V, combinations of V and Mo, combinations of Nb and Mo, or combinations of Nb, V, and Mo, preferably Nb.

[0015] Preferably, the body-centered cubic hydrogen storage alloy is prepared by melt quenching.

[0016] The hydrogen storage alloy prepared by melt quenching has a high content of body-centered cubic phases, which ensures the hydrogen storage performance of the hydrogen storage material.

[0017] Preferably, the induction melting power of the melt rapid quenching method is 10-20kW, for example, it can be 10kW, 12kW, 14kW, 15kW, 16kW, 18kW or 20kW, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0018] Preferably, the linear velocity of the melt rapid quenching method is 10-30 m / s, for example, it can be 10 m / s, 12 m / s, 14 m / s, 16 m / s, 18 m / s, 20 m / s, 22 m / s, 24 m / s or 26 m / s, 28 m / s, 30 m / s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the body-centered cubic hydrogen storage alloy is a hydrogen storage alloy that has undergone hydrogenation treatment.

[0020] After hydrogenation treatment, the hardness of the hydrogen storage alloy decreases, and its ball milling properties improve. The particle size of the hydrogen storage alloy after ball milling is uniform and its dispersibility is good. The resulting magnesium-based hydrogen storage material has a uniform composition, which helps to improve the performance of the resulting magnesium-based hydrogen storage material. At the same time, after hydrogenation, the hydrogen storage alloy expands in volume and forms cracks or breaks, forming a large number of fine micro / nano-scale hydrogenated body-centered cubic hydrogen storage alloys, generating more hydrogen diffusion channels, and its hydrogen absorption and desorption capacity can be further improved.

[0021] Preferably, the hydrogenation treatment method includes: activating the TiCrNb hydrogen storage alloy and performing a hydrogen absorption reaction to achieve hydrogen absorption saturation.

[0022] Preferably, the activation temperature is 300-500℃, for example, it can be 300℃, 320℃, 340℃, 350℃, 360℃, 280℃, 400℃, 420℃, 440℃, 450℃, 460℃, 480℃ or 500℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0023] Preferably, the hydrogen pressure for the hydrogen absorption reaction is 40-100 bar, for example, it can be 40 bar, 45 bar, 50 bar, 55 bar, 60 bar, 65 bar, 70 bar, 75 bar, 80 bar, 85 bar, 90 bar, 95 bar or 100 bar, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0024] In a second aspect, the present invention provides a method for preparing a magnesium-based hydrogen storage material as described in the first aspect, the method comprising the following steps:

[0025] The hydrogen storage alloy powder with a body-centered cubic structure and MgH2 powder were mixed and ball-milled.

[0026] The preparation method provided by this invention involves ball milling MgH2 into a hydrogen storage alloy, thereby compositing different hydrogen storage material systems at the nanoscale. The MgH2 powder in the raw material is spherical particle powder, and the hydride powder of the hydrogen storage alloy is equiaxed nanocrystalline particles. After ball milling, the average particle size of the material is 100-200 nm, and a micro / nano multiphase structure is formed in situ in the material. The high-density phase boundaries formed at the nanoscale produce a synergistic effect. Various phase boundaries serve as catalytic sites, providing a large number of hydrogen diffusion channels, further accelerating the dissociation and recombination of hydrogen molecules, effectively reducing the dehydrogenation temperature, improving kinetic performance, and achieving a rapid hydrogen absorption and desorption rate, which has good prospects for industrial application.

[0027] Preferably, the particle size of the body-centered cubic hydrogen storage alloy powder is in the range of 1-10 μm, for example, it can be 1 μm, 2 μm, 4 μm, 5 μm, 6 μm, 8 μm or 10 μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0028] Preferably, the particle size of the MgH2 powder is in the range of 1-10 μm, for example, it can be 1 μm, 2 μm, 4 μm, 5 μm, 6 μm, 8 μm or 10 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, the ball-to-material ratio of the ball mill is (80-120):1, for example, it can be 80:1, 85:1, 90:1, 95:1, 100:1, 105:1, 110:1, 115:1 or 120:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Preferably, the ball milling is carried out in a hydrogen atmosphere.

[0031] Preferably, the diameter of the grinding ball in the ball mill is 6-10 mm, for example, it can be 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the rotational speed of the ball mill is 400-600 rpm / min, for example, it can be 400 rpm / min, 410 rpm / min, 420 rpm / min, 430 rpm / min, 440 rpm / min, 450 rpm / min, 460 rpm / min, 470 rpm / min, 480 rpm / min, 490 rpm / min, 500 rpm / min, 510 rpm / min, 520 rpm / min, 530 rpm / min, 540 rpm / min, 550 rpm / min, 560 rpm / min, 570 rpm / min, 580 rpm / min, 590 rpm / min or 600 rpm / min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0033] Preferably, the ball milling time is 8-24 hours, for example, it can be 8 hours, 10 hours, 12 hours, 14 hours, 15 hours, 16 hours, 18 hours, 20 hours, 22 hours or 24 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The magnesium-based hydrogen storage material provided by this invention combines a body-centered cubic hydrogen storage alloy with MgH2, which effectively reduces the dehydrogenation temperature of the magnesium-based hydrogen storage material, improves its hydrogen absorption and desorption kinetics, and enables rapid hydrogen absorption and desorption. At the same time, it overcomes the defect of the reduction in hydrogen storage capacity of magnesium-based hydrogen storage materials caused by catalyst composite modification in the prior art. The preparation process is simple and has good application prospects. Attached Figure Description

[0036] Figure 1 The image shows the XRD pattern of the TiCrNb hydrogen storage alloy prepared in Example 2.

[0037] Figure 2The image shows the XRD pattern of the magnesium-based hydrogen storage material modified by the hydrogen storage alloy prepared in Example 2.

[0038] Figure 3 This is a SEM image of the magnesium-based hydrogen storage material modified with a hydrogen storage alloy as prepared in Example 2.

[0039] Figure 4 These are temperature-programmed desorption curves of the magnesium-based hydrogen storage materials prepared in Examples 1, 2, and 4 and Comparative Example 1.

[0040] Figure 5 This is the isothermal hydrogen desorption curve of the magnesium-based hydrogen storage material prepared in Example 4 and Comparative Example 1.

[0041] Figure 6 This is the isothermal hydrogen absorption curve of the magnesium-based hydrogen storage material prepared in Example 4 and Comparative Example 1.

[0042] Figure 7 This is the isothermal hydrogen absorption curve of the magnesium-based hydrogen storage material prepared in Comparative Example 1.

[0043] Figure 8 The graphs show the isothermal hydrogen desorption curves of the magnesium-based hydrogen storage materials prepared in Example 4 and Comparative Examples 2-3. Detailed Implementation

[0044] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0045] Example 1

[0046] This embodiment provides a magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite. The raw material for the magnesium-based hydrogen storage material includes a hydrogen storage alloy Ti. 45 Cr 40 Nb 15 Hydride powder and MgH2 powder, Ti 45 Cr 40 Nb 15 The amount of hydride powder added is 5 wt% of the total mass of the raw material powder.

[0047] The preparation method of the magnesium-based hydrogen storage material is as follows:

[0048] (1) The elemental metals were batched according to the chemical formula of the hydrogen storage alloy. The purity of each elemental raw material was 99.9%. 10g of the batch was melted in a non-vacuum consumable arc furnace with a melting vacuum of 2.0×10⁻⁶. -3Pa, after the crucible cooled to room temperature, was turned over and melted four times to ensure uniform alloy melting. Then, the surface oxide layer of the melted cast alloy ingot was polished off, crushed, and 5g was weighed and placed in a quartz tube. The tube was then placed in a vacuum strip melting furnace, and the melt was rapidly quenched at an induction melting power of 15kW and a melt quenching linear velocity of 20m / s. The molten alloy was rapidly spun into thin strips on copper rollers to obtain rapidly quenched Ti. 45 Cr 40 Nb 15 The hydrogen storage alloy was then collected and placed in the reactor of the PCT equipment. After activation at 400°C for 1 hour, it was placed in a water bath and kept at a constant temperature of 25°C. High-purity hydrogen gas of 80 bar was introduced into the reactor. After the hydrogen was fully absorbed, it was activated at 400°C for 1 hour again. The above activation and hydrogen absorption steps were repeated until the sample was finally saturated with hydrogen to obtain the rapidly quenched hydrogen storage alloy hydride powder.

[0049] (2) In a glove box with argon purity of 99.999%, under anhydrous and oxygen-free conditions, weigh the rapidly quenched hydrogen storage alloy hydride powder and MgH2 powder. The particle size range of MgH2 powder is 1-10μm and the purity is 98%. Then, mix the weighed powders in proportion and put them into a 250mL stainless steel ball mill jar with a valve. Add stainless steel grinding balls with a diameter of 8mm according to the ball-to-material ratio of 80:1. Remove the ball mill jar with powder and grinding balls from the glove box and fill it with 50bar hydrogen through the gas valve to prevent MgH2 from decomposing during long-term ball milling. Then, install a planetary ball mill and rotate it forward and backward at 500rpm / s for a total ball milling time of 24h. Every 6h, the ball mill needs to be put into the glove box for scraping to prevent the material from sticking to the wall. After ball milling, the magnesium-based hydrogen storage material modified by the hydrogen storage alloy is obtained.

[0050] Example 2

[0051] This embodiment provides a magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite. The raw material for the magnesium-based hydrogen storage material includes a hydrogen storage alloy Ti. 45 Cr 40 Nb 15 Hydride powder and MgH2 powder, Ti 45 Cr 40 Nb 15 The amount of hydride powder added is 10 wt% of the total mass of the raw material powder.

[0052] The preparation method of the magnesium-based hydrogen storage material is as follows:

[0053] (1) The elemental metals were batched according to the chemical formula of the hydrogen storage alloy. The purity of each elemental raw material was 99.9%. 10g of the batch was melted in a non-vacuum consumable arc furnace with a melting vacuum of 2.0×10⁻⁶. -3 Pa, after the crucible cooled to room temperature, was turned over and melted four times to ensure uniform alloy melting. Then, the surface oxide layer of the melted cast alloy ingot was polished off, crushed, and 5g was weighed and placed in a quartz tube. The tube was then placed in a vacuum strip melting furnace, and the melt was rapidly quenched at an induction melting power of 20kW and a quenching linear velocity of 20m / s. The molten alloy was quickly spun into thin strips on copper rollers to obtain rapidly quenched Ti. 45 Cr 40 Nb 15 The hydrogen storage alloy was then collected and placed in the reactor of the PCT equipment. After activation at 400°C for 1 hour, it was placed in a water bath and kept at a constant temperature of 25°C. High-purity hydrogen gas of 80 bar was introduced into the reactor. After the hydrogen was fully absorbed, it was activated at 400°C for 1 hour again. The above activation and hydrogen absorption steps were repeated until the sample was finally saturated with hydrogen to obtain the rapidly quenched hydrogen storage alloy hydride powder.

[0054] (2) In a glove box with argon purity of 99.999%, under anhydrous and oxygen-free conditions, weigh the rapidly quenched hydrogen storage alloy hydride powder and MgH2 powder. The particle size range of MgH2 powder is 1-10μm and the purity is 98%. Then, mix the weighed powders in proportion and put them into a 250mL stainless steel ball mill jar with a valve. Add stainless steel grinding balls with a diameter of 8mm according to a ball-to-material ratio of 120:1. Remove the ball mill jar with powder and grinding balls from the glove box and fill it with 50bar hydrogen through the gas valve for protection. Then, install a planetary ball mill and rotate it forward and backward at a speed of 500rpm / s. Mill for 12 minutes and rest for 6 minutes, for a total milling time of 12 hours. Every 4 hours, the material needs to be scraped in the glove box to prevent it from sticking to the wall. After the milling is completed, the magnesium-based hydrogen storage material modified by the hydrogen storage alloy is obtained.

[0055] Example 3

[0056] This embodiment provides a magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite. Compared with Example 1, Ti 45 Cr 40 Nb 15 The amount of hydride powder added is 15 wt% of the total mass of the raw material powder.

[0057] The preparation method of the magnesium-based hydrogen storage material is the same as that in Example 1.

[0058] Example 4

[0059] This embodiment provides a magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite. Compared with Example 1, Ti 45 Cr 40 Nb 15 The amount of hydride powder added is 20 wt% of the total mass of the raw material powder.

[0060] The preparation method of the magnesium-based hydrogen storage material is the same as that in Example 1.

[0061] Example 5

[0062] This embodiment provides a magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite. Compared with Example 1, Ti 45 Cr 40 Nb 15 The amount of hydride powder added is 2 wt% of the total mass of the raw material powder.

[0063] The preparation method of the magnesium-based hydrogen storage material is the same as that in Example 1.

[0064] Example 6

[0065] This embodiment provides a magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite. Compared with Example 1, Ti 45 Cr 40 Nb 15 The amount of hydride powder added is 30 wt% of the total mass of the raw material powder.

[0066] The preparation method of the magnesium-based hydrogen storage material is the same as that in Example 1.

[0067] Example 7

[0068] This embodiment provides a magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite. The raw material for the magnesium-based hydrogen storage material includes a hydrogen storage alloy Ti. 35 Cr 55 Nb5 hydride powder and MgH2 powder, Ti 35 Cr 55 The amount of Nb5 hydride powder added is 5 wt% of the total mass of the raw material powder.

[0069] Example 8

[0070] This embodiment provides a magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite. The raw material for the magnesium-based hydrogen storage material includes a hydrogen storage alloy Ti. 55 Cr 35 Nb 20 Hydride powder and MgH2 powder, Ti 55 Cr 35 Nb 20 The amount of hydride powder added is 5 wt% of the total mass of the raw material powder.

[0071] Example 9

[0072] This embodiment provides a magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite. Compared with Example 1, the hydrogen storage alloy Ti... 45 Cr 40 Nb 15 The hydride powder was replaced in equal amounts with an unhydrogenated hydrogen storage alloy Ti. 45 Cr 40 Nb 15 powder.

[0073] Compared with Example 1, the preparation method of the magnesium-based hydrogen storage material does not involve activation and hydrogen absorption processes in step (1).

[0074] Example 10

[0075] This embodiment provides a magnesium-based hydrogen storage material with hydrogen storage alloy composite modification. In the preparation method of the magnesium-based hydrogen storage material, compared with Example 1, step (1) does not involve melt quenching, and the rest is the same as Example 1.

[0076] Example 11

[0077] This embodiment provides a magnesium-based hydrogen storage material modified by a hydrogen storage alloy. The preparation method of the magnesium-based hydrogen storage material is the same as that of Example 1, except that the ball milling speed in step (2) is 400 rpm / min.

[0078] Example 12

[0079] This embodiment provides a magnesium-based hydrogen storage material modified by a hydrogen storage alloy. The preparation method of the magnesium-based hydrogen storage material is the same as that of Example 1, except that the ball milling speed in step (2) is 600 rpm / min.

[0080] Example 13

[0081] This embodiment provides a composite modified magnesium-based hydrogen storage material, which, compared with Example 1, incorporates a hydrogen storage alloy Ti... 45 Cr 40 Nb 15 The hydride powder was replaced in equal amounts with hydrogen storage alloy Ti. 45 Cr 40 V 15 powder.

[0082] Comparative Example 1

[0083] This comparative example provides a magnesium-based hydrogen storage material, which is MgH2 ball-milled using the same ball-milling parameters as in Example 1.

[0084] Comparative Example 2

[0085] This comparative example provides a composite modified magnesium-based hydrogen storage material, which, compared to Example 1, incorporates a hydrogen storage alloy Ti... 45 Cr 40 Nb 15 The hydride powder was replaced with an equal amount of Ti powder.

[0086] Comparative Example 3

[0087] This comparative example provides a composite modified magnesium-based hydrogen storage material, which, compared to Example 1, incorporates a hydrogen storage alloy Ti... 45 Cr 40 Nb 15 The hydride powder was replaced with an equal amount of Nb powder.

[0088] The magnesium-based hydrogen storage materials provided in the embodiments and comparative examples of the present invention were subjected to hydrogen programmed temperature desorption (TPD) and isothermal hydrogen absorption and desorption performance tests. The table lists the average hydrogen absorption and desorption rates of each embodiment and comparative example at 250°C for isothermal hydrogen desorption and at 150°C for isothermal hydrogen absorption, in order to illustrate the hydrogen storage performance of the materials.

[0089] Table 1

[0090]

[0091]

[0092] As shown in Table 1, the magnesium-based hydrogen storage material provided by this invention effectively reduces the initial dehydrogenation temperature of magnesium-based hydrogen storage materials, lowering it by up to 100°C. It also exhibits rapid hydrogen absorption and desorption rates, improving the hydrogen storage kinetics of MgH2 materials. Furthermore, it significantly enhances the hydrogen storage capacity of magnesium-based hydrogen storage materials. Different amounts of hydrogen storage alloys added do not affect the hydrogen absorption capacity. However, compared to Example 1, in Example 9, the hydrogen storage alloy was not hydrogenated, affecting the ball milling composite effect and potentially leading to uneven composition of the resulting magnesium-based hydrogen storage material, resulting in a slight decrease in its hydrogen storage performance. In Example 10, the absence of melt quenching may have reduced the content of the body-centered cubic (BCC) phase in the hydrogen storage alloy, thus affecting the material's hydrogen storage performance. In Examples 11 and 12, changing the ball milling speed affected the alloy composite effect during ball milling, resulting in a slight decrease in performance.

[0093] Figure 1 The images show the XRD patterns of the TiCrNb hydrogen storage alloy (denoted as the rapidly quenched state) and the TiCrNb hydrogen storage alloy hydride (denoted as the hydrogenated state) prepared in Example 2. The TiCrNb hydrogen storage alloy has a BCC phase structure. Figure 2The XRD patterns of the magnesium-based hydrogen storage material modified by the hydrogen storage alloy prepared in Example 2 at different ball milling times (4h, 8h and 12h) are shown in the figure. The main peak is the diffraction peak of the MgH2 phase, and a small amount of diffraction peak of the FCC phase. Figure 3 The SEM images show that the powder particles are fine, indicating that the powder was kneaded for a long time after ball milling, and the TiCrNb hydrogen storage alloy hydride powder and MgH2 were stuck together.

[0094] Figure 4 In Example 4, the initial dehydrogenation temperature of the magnesium-based hydrogen storage material modified with hydrogen storage alloy was 156°C, while the initial dehydrogenation temperature of the magnesium-based hydrogen storage material prepared in Comparative Example 1 was 286°C. The doping of TiCrNb hydrogen storage alloy hydride significantly reduced the hydrogen release temperature of MgH2, and the hydrogen release temperature showed a decreasing trend as the doping amount increased, while maintaining a high hydrogen release capacity.

[0095] Figure 5 In Example 4, the magnesium-based hydrogen storage material modified with hydrogen storage alloy showed a faster hydrogen desorption rate, releasing 5.70 wt% H2 within 500 s, while the MgH2 prepared in Comparative Example 1 hardly released any hydrogen at the same temperature, indicating that the doped TiCrNb hydrogen storage alloy hydride can effectively improve the hydrogen desorption kinetics of MgH2.

[0096] Figure 6 and Figure 7 The hydrogen absorption kinetics curves of the magnesium-based hydrogen storage materials prepared in Example 4 and Comparative Example 1 at different temperatures are shown. It can be seen that the hydrogen absorption capacity of the material prepared in Example 4 reaches 3.50 wt%, 3.8 wt%, 4.51 wt%, and 5.10 wt% within 10 s at temperatures of 30℃, 90℃, 100℃, and 150℃, respectively. In contrast, the hydrogen absorption capacity of MgH2 at 150℃ within 1000 s is less than 2 wt%. This shows that the MgH2 hydrogen storage material doped with 20 wt% TiCrNb hydrogen storage alloy hydride exhibits good low-temperature hydrogen absorption kinetics performance.

[0097] In summary, the magnesium-based hydrogen storage material provided by this invention combines a body-centered cubic hydrogen storage alloy with MgH2, effectively reducing the dehydrogenation temperature of the magnesium-based hydrogen storage material, improving its hydrogen absorption and desorption kinetics, and achieving rapid hydrogen absorption and desorption. At the same time, it overcomes the defect in the prior art where catalyst composite modification reduces the hydrogen storage capacity of magnesium-based hydrogen storage materials. The preparation process is simple and has good application prospects.

[0098] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A magnesium-based hydrogen storage material modified with a hydrogen storage alloy composite, characterized in that, The magnesium-based hydrogen storage material comprises a body-centered cubic hydrogen storage alloy and a MgH2 composite; the body-centered cubic hydrogen storage alloy comprises Ti 45 Cr 40 M 15 M includes any one or at least two combinations of Nb, V or Mo; the body-centered cubic hydrogen storage alloy is prepared by melt quenching and subjected to hydrogenation treatment; the body-centered cubic hydrogen storage alloy accounts for 5-30 wt% of the magnesium-based hydrogen storage material.

2. A method for preparing the magnesium-based hydrogen storage material as described in claim 1, characterized in that, The preparation method includes the following steps: The hydrogen storage alloy powder with a body-centered cubic structure and MgH2 powder were mixed and ball-milled.

3. The preparation method according to claim 2, characterized in that, The ball-to-material ratio of the ball mill is (80-120):

1.

4. The preparation method according to claim 2, characterized in that, The ball milling was carried out under a hydrogen atmosphere.

5. The preparation method according to claim 2, characterized in that, The ball mill rotates at a speed of 400-600 rpm.

6. The preparation method according to claim 2, characterized in that, The ball milling time is 8-24 hours.

7. An application of the magnesium-based hydrogen storage material as described in claim 1, characterized in that, The magnesium-based hydrogen storage material is used for hydrogen storage.

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