A Ti-Mn-based hydrogen storage alloy modified by nanometer zirconium oxide and alloying, and a preparation method and application thereof

Abstract

The application belongs to the technical field of hydrogen storage materials, and discloses a Ti-Mn-based hydrogen storage alloy and a preparation method and application thereof. The chemical general formula of the hydrogen storage alloy is Ti a‑x Zr x Mn y Cr z Fe b Cu c Ni d Al e -f wt%ZrO2, 0.35≤a≤0.4, 0.05≤x≤0.13, 0.2≤y≤0.4, 0.2≤z≤0.3, 0

Description

Technical Field

[0001] This application relates to the field of solid-state hydrogen storage technology, and in particular to a Ti-Mn-based hydrogen storage alloy modified by nano-zirconia and alloying, its preparation method and application. Background Technology

[0002] Hydrogen, as an energy carrier, boasts advantages such as high energy density, cleanliness, and renewability, and is considered a crucial component of the future energy system. However, hydrogen's low density and difficulties in storage and transportation make safe and efficient hydrogen storage technologies key factors restricting the large-scale application of hydrogen energy. Common hydrogen storage methods include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, and solid-state hydrogen storage. Among these, solid-state hydrogen storage based on metal hydrides is considered a promising technology due to its high volumetric hydrogen storage density, low-pressure safety, and high energy efficiency.

[0003] Among numerous metal hydride hydrogen storage materials, Ti-Mn-based AB2-type C14 Laves phase hydrogen storage alloys exhibit good hydrogen absorption and desorption at room temperature, high hydrogen storage capacity, and relatively low cost, attracting widespread attention in transportation, hydrogen energy storage, and backup power applications. However, some challenges remain in practical applications for these alloys: For example, Ti, the element at the A-site that primarily determines the hydrogen storage capacity of the alloy, is easily oxidized, leading to a decrease in the alloy's hydrogen storage capacity. Simultaneously, the formation of a dense titanium dioxide oxide layer hinders hydrogen contact with the alloy surface, weakening the alloy's adsorption of hydrogen molecules and inhibiting the dissociation of hydrogen molecules into hydrogen atoms and their diffusion into the alloy interior, making hydrogen absorption and desorption activation difficult. Furthermore, the cycle stability of Ti-Mn-based AB2-type C14 Laves phase hydrogen storage alloys needs further improvement. These factors, coupled together, limit the practical application of Ti-Mn-based AB2-type C14 Laves phase alloys as solid-state hydrogen storage media.

[0004] To improve the hydrogen storage performance of Ti-Mn-based AB2-type C14 Laves phase alloys, researchers have made continuous attempts from various aspects, including alloy design, microstructure control, and preparation method improvement, achieving some promising results. Among these, alloying to control the alloy's crystal structure and thermodynamic properties is one of the most effective methods. For example, introducing Zr atoms with larger atomic radii at the A-site to increase the cell volume can improve the thermodynamic stability of interstitial hydrogen, thereby reducing the hydrogen absorption / desorption plateau pressure and increasing the alloy's hydrogen storage capacity. Doping Cr, Fe, and Mo at the B-site to partially replace Mn can adjust the interaction strength between hydrogen and metal atoms and the lattice stress, optimizing and improving the alloy's overall hydrogen storage performance, such as improving the hydrogen absorption / desorption plateau characteristics and activation performance. Studies have shown that adding small amounts of rare earth elements such as La or Ce can promote grain refinement during the smelting process, improving the alloy's activation performance. However, rare earth elements are expensive and have large atomic weights, which is not conducive to the development of low-cost, high-capacity hydrogen storage alloys.

[0005] Chinese invention patent application with publication number CN 121406926A improves the composition and microstructure uniformity of the alloy by adding two rare earth elements, La and Ce, and repeatedly remelting and homogenizing at high temperature, thereby suppressing composition and microstructure segregation. Different metal elements such as Ti, Zr and Al are added as activators at different stages of alloy remelting. The maximum hydrogen storage capacity of the prepared alloy is 1.7 wt%.

[0006] Chinese invention patent application CN 117794664A describes an alloying process incorporating rare-earth La and Ce doping, followed by high-temperature heat treatment at 850℃–1150℃. This process improves the hysteresis and slope of the hydrogen absorption / desorption plateau in the alloy, reducing the required hydrogen pressure and activation time. However, it still requires holding the alloy at 5MPa hydrogen pressure for 2 hours, followed by vacuuming for 30 minutes, repeating this cycle three times to fully activate the alloy's hydrogen absorption / desorption.

[0007] Chinese invention patent application CN 121849844A modifies the lattice interstices and the bonding strength between metal atoms and hydrogen atoms by substituting alloying elements, designing a Ti-based alloy. 0.99-x Zr 0.03+x Mn 1.25 Cr 0.5 (VFe) 0.25 For alloys with x=0, 0.05, 0.1, 0.15, the hydrogen storage capacity and platform pressure of the alloy are adjusted. The alloy needs to be charged with 7-8 MPa hydrogen at 100°C for hydrogenation treatment and vacuum dehydrogenation. This process is repeated 3 times to complete the hydrogenation activation of the alloy.

[0008] In terms of alloy preparation technology, Ti-Mn-based AB2-type hydrogen storage alloys are mainly prepared using two traditional methods: vacuum induction melting and electric arc melting. During the alloy melting and solidification process, due to the significant differences in density and melting point among different metal components, alloy composition and microstructure segregation easily occurs, affecting the alloy's compositional uniformity and hydrogen storage performance. To eliminate segregation, long-term high-temperature homogenization annealing is usually required, which is energy-intensive and time-consuming. High-temperature heat treatment equipment requires large investments and depreciates rapidly, increasing the alloy's production cost. Furthermore, some strong-affinity alloying elements easily form intermetallic compounds, resulting in the formation of a second phase in the alloy. For example, when La and Ni coexist, LaNi5 is easily formed, and Ti and Ni form the TiNi phase. The presence of these low-hydrogen-storage or non-hydrogen-storage phases reduces the effective hydrogen storage capacity of the system. Secondly, impurity gases during hydrogen absorption and desorption, such as oxygen and water vapor, easily lead to alloy oxidation, resulting in capacity loss and a decline in hydrogen storage performance. Improving the alloy's oxidation resistance is also a significant challenge for the application of this type of alloy. Summary of the Invention

[0009] The purpose of this application is to provide a high-capacity, long-life AB2-type C14 Laves phase Ti-Mn-based solid hydrogen storage alloy that is easily activated at room temperature and low hydrogen pressure, and its preparation method, so as to solve the problems of long activation cycle, high activation temperature and high required hydrogen pressure of Ti-Mn-based AB2-type C14 Laves phase hydrogen storage alloy, while improving the hydrogen storage capacity and hydrogen absorption / desorption cycle life of the alloy, and maintaining the advantage of low cost. In terms of alloy composition design, this application adopts a strategy of dual substitution of alloying elements at both the A-site and B-site, with the A-site exceeding the stoichiometric ratio. Simultaneously, an appropriate amount of nano-zirconia is added during alloy melting as a nucleating agent to promote the nucleation of the C14 Laves phase during alloy melt solidification. Furthermore, the heterogeneous phase enhances interfacial energy to inhibit excessive grain growth of the C14 Laves phase. During hydrogen absorption and desorption, the added nano-zirconia is dispersed within and at the grain boundaries of the C14 Laves phase, generating numerous heterogeneous phase interfaces that provide channels for hydrogen atom diffusion, accelerating hydrogen diffusion within the alloy bulk. Moreover, the presence of nano-zirconia within the grains and at grain boundaries effectively relaxes the lattice stress generated by the cell volume changes during hydrogen absorption and desorption of the AB2-type C14 Laves phase, improving the alloy bulk's resistance to hydrogen-induced pulverization, thereby enhancing the hydrogen storage alloy's hydrogen absorption and desorption cycle life and capacity retention.

[0010] To achieve the above objectives, this application provides the following technical solution: The Ti-Mn-based hydrogen storage alloy provided in this application has a C14 Laves phase structure, and its components include Ti, Zr, Mn, Cr, Fe, Cu, Ni, Al, and nano-zirconia; the general chemical formula of the hydrogen storage alloy is Ti a-x Zr x Mn y Crz Fe b Cu c Ni d Al e -f wt% ZrO2, wherein 0.35≤a≤0.4, 0.05≤x≤0.13, 0.2≤y≤0.4, 0.2≤z≤0.3, 0<b<0.15, 0<c≤0.1, 0≤d≤0.1, 0≤e≤0.1, and 0.6≤y+z+b+c+d+e≤0.7 is satisfied; wherein 5≤f≤15, and based on the total mass of the hydrogen storage alloy being 100%, the mass fraction of the nano zirconia is 5-15%.

[0011] In some embodiments, the nano zirconia is dispersedly distributed inside the crystal grains and at the grain boundaries of the hydrogen storage alloy.

[0012] In some embodiments, the oxygen content in the hydrogen storage alloy is not higher than 5.5 wt%.

[0013] In some embodiments, when the general chemical formula includes Ni, the oxygen content in the hydrogen storage alloy is not higher than 2.41 wt%.

[0014] In some embodiments, the nano zirconia is dispersedly distributed inside the crystal grains and at the grain boundaries of the hydrogen storage alloy, the crystal grains of the hydrogen storage alloy are uniform in size, and the grain size is 1-3µm.

[0015] The present application also provides a preparation method of the Ti-Mn based hydrogen storage alloy as described above, comprising the following steps: S1, weighing each metal elemental raw material Ti, Zr, Mn, Cr, Fe, Cu, Al, Ni according to the general chemical formula of the hydrogen storage alloy, and weighing the formulated amount of nano zirconia; S2, placing all raw materials in the water-cooled copper crucible in the sample chamber of a vacuum non-consumable arc melting furnace according to a certain stacking method for melting, and repeating melting for 3 to 5 times to obtain an alloy melt; S3, rapidly cooling the alloy melt by suction casting to obtain an as-cast alloy; S4, subjecting the as-cast alloy to homogenization annealing at 980 to 1150°C for 6 to 24 hours, and cooling to obtain the Ti-Mn based hydrogen storage alloy.

[0016] In some embodiments, in S1, when weighing the metal elemental raw materials, additional Mn of no more than 15 wt% is added to compensate for smelting loss.

[0017] In some embodiments, the purity of the elemental metal raw materials Ti, Zr, Mn, Cr, Fe, Cu, Al, and Ni is ≥99.8%; the nano-zirconia is nanoscale powder; before weighing, the surface of the Ti raw material is treated to remove oxide scale, and moisture and air are removed.

[0018] In some embodiments, S2 includes the following process: The prepared raw materials were subjected to vacuum non-consumable arc melting: during sample loading, titanium, zirconium, and nickel were placed in the lower layer, chromium, iron, and copper in the upper layer, manganese and aluminum in the middle layer, and nano-zirconia was placed last; before melting, the vacuum was repeatedly evacuated more than 3 times, and the sample chamber was cleaned with high-purity argon; then the vacuum was evacuated again to ≤10. -3 After Pa, electric arc melting is carried out; before starting to melt the alloy sample, the titanium ingot in the middle of the water-cooled copper crucible is melted repeatedly 3 times or more, and the residual trace oxygen impurity gas in the sample chamber is absorbed by the high-temperature titanium before the sample is melted. In the initial stage of melting alloy samples, a small current ≤100A is used for pre-alloying to pre-alloy low-melting-point volatile alloy components, thereby reducing melting quality loss. Then, the melting current is gradually increased until all components are completely melted, and magnetic stirring is started. After the first melting is completed and the alloy solution has solidified, the alloy sample is flipped over for a second remelting. This process is repeated 3-5 times.

[0019] This application also provides an application of the Ti-Mn-based hydrogen storage alloy as described above, which can be used as a solid hydrogen storage medium in on-board hydrogen supply systems, hydrogen fuel cell backup power supplies, hydrogen storage or hydrogen transportation devices.

[0020] Compared with the prior art, the solution of this application has the following advantages: This application significantly improves the overall performance of Ti-Mn-based AB2-type C14 Laves phase hydrogen storage alloys through synergistic modification of nano-zirconia and A / B dual-site alloying. First, the introduction of nano-zirconia effectively refines the C14 Laves phase grains, dispersing them within the grains and at grain boundaries, providing more channels for hydrogen diffusion and alleviating lattice stress during hydrogen absorption and desorption, thus greatly improving the alloy's resistance to pulverization and cycle stability. Second, the addition of Ni and Al elements significantly improves the alloy's oxidation resistance and reduces the oxygen content, allowing the alloy to be activated in just 1-3 hydrogen absorption and desorption cycles under mild conditions, demonstrating excellent activation performance. Simultaneously, the alloy exhibits a high effective hydrogen desorption capacity and maintains a low-cost advantage by not using rare earth elements or vanadium.

[0021] In summary, this application achieves a balance between easy activation, high capacity, long lifespan, and low cost, providing an ideal solution for the practical application of solid-state hydrogen storage materials. Attached Figure Description

[0022] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0023] Figure 1 The X-ray diffraction patterns of the three hydrogen storage alloys prepared in Examples 1-3 of this application are shown, all of which have a C14Laves phase structure.

[0024] Figure 2 The image shows the scanning electron microscope morphology and elemental distribution of the sample prepared in Example 1.

[0025] Figure 3 The image shows the microstructure of the sample prepared in Example 2 using a scanning electron microscope.

[0026] Figure 4 This is a scanning electron microscope image of the alloy sample prepared in Example 3.

[0027] Figure 5 The hydrogen absorption and desorption activation curves are for the hydrogen storage alloy sample prepared in Example 2.

[0028] Figure 6 The hydrogen absorption and desorption cycle curves are for the hydrogen storage alloy sample prepared in Example 2.

[0029] Figure 7 The dehydrogenation PCT curve of the hydrogen storage alloy sample prepared in Example 2 at 25°C.

[0030] Figure 8 The hydrogen absorption and desorption kinetics curves of the hydrogen storage alloy sample prepared in Example 1 at different temperatures are shown.

[0031] Figure 9 The dehydrogenation PCT curve of the hydrogen storage alloy sample prepared in Example 1 at 30°C.

[0032] Figure 10 The hydrogen storage alloy sample prepared in Example 3 is shown in the low-temperature and low-pressure hydrogen absorption kinetic curve after two hydrogen absorption and desorption activations.

[0033] Figure 11 The hydrogen storage alloy sample prepared for Comparative Example 1 is shown in the hydrogen absorption and degassing cycle activation curve after being degassed under vacuum at 100°C for 30 minutes. Detailed Implementation

[0034] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention, but not to limit the invention. It should also be noted that, for the convenience of description, only the parts related to the invention are shown in the accompanying drawings.

[0035] It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0036] The present application provides a Ti-Mn based hydrogen storage alloy synergistically modified by nano-zirconia and alloying and a preparation method thereof. The solution specifically includes the following contents and steps: The hydrogen storage alloy has a C14 Laves phase structure, and its components include Ti, Zr, Mn, Cr, Fe, Cu, Ni, Al and nano-zirconia; the general chemical formula of the hydrogen storage alloy is Ti a-x Zr x Mn y Cr z Fe b Cu c Ni d Al e -f wt% ZrO₂, wherein 0.35≤a≤0.4, 0.05≤x≤0.13, 0.2≤y≤0.4, 0.2≤z≤0.3, 0<b<0.15, 0<c≤0.1, 0≤d≤0.1, 0≤e≤0.1, and 0.6≤y+z+b+c+d+e≤0.7 is satisfied; wherein 5≤f≤15, based on the total mass of the hydrogen storage alloy as 100%, the mass fraction of the nano-zirconia is 5-15%.

[0037] The specific preparation process is as follows: Weigh each elemental metal raw material Ti, Zr, Mn, Cr, Fe, Cu, Al, Ni according to the pre-designed composition and proportion; then weigh a certain amount of nano-zirconia, and the addition amount of nano-zirconia is less than 15% by mass fraction. For manganese, an alloy component with high saturated vapor pressure that is easily volatile, an additional melting loss of ≤15wt% is added when preparing alloy samples.

[0038] Wherein, the purity of each selected pure metal component raw material is ≥99.8%. Before weighing, remove the oxide scale on the surface of the titanium raw material, and remove moisture and adsorbed air.

[0039] The prepared alloy composition was subjected to vacuum non-consumable arc melting using a water-cooled copper crucible. During sample loading, titanium, zirconium, and nickel were placed in the bottom layer; chromium, iron, and copper in the top layer; manganese and aluminum in the middle layer; and nano-zirconia was placed last. Before melting, the sample chamber was repeatedly evacuated at least three times and cleaned with high-purity argon (≥99.999%). The vacuum was then reduced to ≤10 °C. -3 Pa is used for arc melting. Before starting to melt the alloy sample, the titanium ingot in the central water-cooled copper crucible is repeatedly melted 3 times or more. The high-temperature titanium absorbs the residual trace amounts of oxygen and other impurity gases in the sample chamber before the sample is melted.

[0040] In the initial stage of melting alloy samples, a small current ≤100A is used to pre-alloy low-melting-point volatile alloy components to reduce melting quality loss. Then, the melting current is gradually increased until all components are completely melted, and magnetic stirring is started.

[0041] After the first melting is completed and the alloy solution has solidified, the alloy sample is flipped over for a second remelting. This process is repeated 3-5 times.

[0042] In the final melting process, the alloy mother solution is drawn into a water-cooled copper mold for rapid cooling using a suction casting method. After cooling to room temperature, the ingot is removed to obtain the initial alloy sample.

[0043] The initial alloy sample is placed in a heat treatment furnace, and a vacuum is drawn or high-purity argon is introduced. Diffusion annealing is carried out in the temperature range of 980 to 1150°C for 6 to 24 hours to obtain the final hydrogen storage alloy sample.

[0044] It should be noted that the same effect can be achieved by using induction melting combined with rapid quenching or strip spinning methods, and it is not limited to vacuum non-consumable arc melting.

[0045] The innovative design concept and beneficial effects of this application are as follows: This application innovatively enhances the hydrogen storage performance of AB2-type C14 Laves phase alloys through the synergistic effect of adding nano-zirconia and dual-site element substitution alloying at both A and B sites. By adding nano-zirconia, nucleation during the solidification process of the smelting alloy is promoted, while the heterogeneous interface inhibits excessive grain growth, controlling the C14 Laves phase grain size to approximately 2µm. The nano-zirconia generates a heterogeneous interface, providing more channels for hydrogen diffusion and alleviating the lattice stress generated by hydrogen absorption and desorption in the C14 Laves phase. This not only helps release the lattice stress caused by lattice expansion due to hydrogen absorption and desorption, improving the alloy's resistance to hydrogen-induced pulverization and thus enhancing the alloy's hydrogen absorption and desorption cycle stability, but also facilitates the alloy's hydrogen absorption and desorption activation. Dual-site element substitution alloying at both A and B sites, particularly the addition of appropriate amounts of Ni and Al at the B site, reduces the oxygen content in the alloy, improving the oxidation resistance of the hydrogen storage alloy and significantly enhancing its hydrogen storage performance, especially its low-temperature hydrogen absorption and desorption activation performance while maintaining high capacity characteristics. Secondly, this application avoids the use of rare and precious metals, such as V, Mo, and rare earth elements, ensuring the low-cost advantage of the alloy and making it more conducive to commercial applications. In summary, by adding nano-zirconia combined with a dual-site alloying strategy, especially by adding small amounts of nickel and aluminum, a low-cost AB2-type C14Laves phase hydrogen storage alloy with easy activation, high capacity, and long cycle life was designed and developed.

[0046] To verify the effectiveness of the proposed solution, the following embodiments are proposed: The alloy composition table (weight of elemental metals and ZrO2) and the oxygen content data of the alloys obtained in the examples are shown in Table 1 below: Table 1. Alloy composition and oxygen content

[0047] The specific preparation process of this embodiment is as follows: Example 1: (1) Weigh each pure metal component according to the alloy composition of Example 1 in Table 1, with an additional 5 wt% melt loss for manganese. The titanium raw material was pre-treated to remove the oxide layer from its surface, and then dried, dehydrated, and degassed.

[0048] (2) Titanium and zirconium are placed at the bottom of the water-cooled copper crucible of the smelting furnace, manganese and copper are placed in the middle, chromium and iron are placed on top, and finally nano-zirconium oxide powder is placed on top.

[0049] (3) Vacuum the sample chamber. After the first vacuuming, fill it with 99.999% high-purity argon gas and perform the second vacuuming. Repeat the vacuuming and gas washing operation three times.

[0050] (4) After step 3 is completed, evacuate to ≤10 -3Then, the titanium ingot in the middle of the water-cooled copper crucible was melted for 5 minutes using a high current to remove trace amounts of oxygen and other impurity gases from the sample chamber environment.

[0051] (5) After step 4 is completed, heat the sample with a small current ≤100A to pre-alloy the low melting point volatile alloy components and reduce the melting loss of volatile manganese elements with high saturated vapor pressure.

[0052] (6) After the small current pre-alloying in step 5 is completed, gradually increase the melting current until all alloy components are melted, and at the same time turn on the magnetic stirring to make the alloy composition uniform.

[0053] (7) After step 6 is completed, wait for the molten alloy mother liquid to cool and solidify, then turn it over and remelt it. Apply magnetic stirring during the melting process. Repeat this melting process 5 times.

[0054] (8) After the alloy is fully melted in step 7, the vacuum casting chamber is evacuated and the casting operation is performed. The molten alloy liquid is sucked into the water-cooled copper mold and solidified quickly by the vacuum negative pressure suction. The alloy ingot / rod is then cooled to room temperature to obtain the cast alloy ingot / rod.

[0055] (9) The cast alloy ingot / rod obtained in step 8 is placed into a heat treatment furnace and subjected to homogenization diffusion annealing at 980°C under vacuum or high-purity argon protection for 24 hours. After the heat treatment is completed, the alloy is slowly cooled to room temperature in the furnace.

[0056] (10) After step 9 is completed, the oxide layer on the alloy surface is removed by grinding to obtain the hydrogen storage alloy sample of this application.

[0057] The test results for this embodiment are as follows: like Figure 1 Example 1 is the hydrogen storage alloy Ti prepared in this application. 0.30 Zr 0.10 Mn 0.28 Cr 0.20 Fe 0.10 Cu 0.02 The X-ray diffraction pattern of -5wt%ZrO2 indicates that the alloy has a C14 Laves phase structure.

[0058] Figure 2The image shows the scanning electron microscope (SEM) microstructure and elemental distribution of the alloy prepared in Example 1 of this application. The SEM images reveal that nano-zirconia is dispersed within the Ti-Mn-based C14 Laves phase matrix and grain boundaries. The introduction of zirconia nanoparticles creates nano-second phase interfaces within the Ti-Mn-based C14 Laves phase grains, enhancing hydrogen atom diffusion during hydrogen absorption and desorption. Furthermore, the zirconia nanoparticles dispersed within and at the grain boundaries of the C14 Laves phase grains alleviate lattice stress generated during hydrogen storage, enhancing the anti-pulverization properties of the hydrogen-absorbing phase in the matrix, thereby improving the alloy's hydrogen absorption and desorption cycle life. The alloy grain size is approximately 3 µm, which is beneficial for alloy activation and sufficient hydrogen absorption.

[0059] Figure 8 The hydrogen storage alloy prepared in Example 1 was degassed under vacuum at 100°C for 30 minutes, and then activated by hydrogen absorption and desorption at 4°C and 5 MPa hydrogen pressure, and at 18°C ​​and 5 MPa hydrogen pressure. The activation curves in the figure show that: At 4°C and 5 MPa hydrogen pressure, after a hydrogenation incubation period of about 1-2 minutes, the alloy began to absorb hydrogen significantly, and the amount of hydrogen absorbed reached about 1.7 wt% after 7.5 minutes.

[0060] At 18°C ​​and 5 MPa hydrogen pressure, after a hydrogenation incubation period of less than 1 minute, the alloy began to absorb hydrogen significantly, and the amount of hydrogen absorbed reached about 1.7 wt% after 2.5 minutes.

[0061] Figure 9 The figure shows the dehydrogenation PCT curve of the hydrogen storage alloy at 30℃. As can be seen from the figure, the alloy releases 1.72 wt% of hydrogen in the pressure range of 0.01–6.0 MPa. The hydrogen release plateau pressure is approximately 0.74 MPa. This alloy exhibits a moderate plateau pressure and high effective hydrogen storage capacity, which can well meet the requirements of solid-state hydrogen storage and supply systems such as fuel cell backup power supplies. It is a type of solid-state hydrogen storage alloy that combines easy activation and high capacity. Furthermore, the alloy does not use rare and precious metals such as vanadium and rare earth elements, giving it a low-cost advantage.

[0062] Example 2 Based on Example 1, the alloy composition and proportions were appropriately adjusted, as shown in Table 1 of Example 2. Specifically, 0.07 moles of nickel were added to the alloy. The hydrogen storage alloy Ti was prepared according to the alloy preparation process. 0.27 Zr 0.13 Mn 0.20 Cr 0.20 Fe 0.11 Cu 0.02 Ni 0.07 -8wt% ZrO2. The preparation process is as follows: (1) Weigh each pure metal component according to the alloy composition of Example 2 in Table 1, with an additional 5 wt% melt loss for manganese. The titanium raw material was pre-treated to remove the oxide layer from its surface.

[0063] (2) Titanium and zirconium are placed at the bottom of the water-cooled copper crucible of the smelting furnace, manganese and copper are placed in the middle, chromium and iron are placed on top, and finally nano-zirconium oxide powder is placed on top.

[0064] (3) Vacuum the sample chamber. After the first vacuuming, fill it with 99.999% high-purity argon gas and perform the second vacuuming. Repeat the vacuuming and gas washing operation three times.

[0065] (4) After step 3 is completed, evacuate to ≤10 -3 Then, the titanium ingot in the middle of the water-cooled copper crucible was melted for 10 minutes using a high current to remove trace amounts of oxygen and other impurity gases from the sample chamber environment.

[0066] (5) After step 4 is completed, heat the sample with a small current ≤100A to pre-alloy the low melting point volatile alloy components and reduce the melting loss of volatile manganese elements with high saturated vapor pressure.

[0067] (6) After the small current pre-alloying in step 5 is completed, gradually increase the melting current until all alloy components are melted, and at the same time turn on the magnetic stirring to make the alloy composition uniform.

[0068] (7) After step 6 is completed, wait for the molten alloy mother liquid to cool and solidify, then turn it over and remelt it. Apply magnetic stirring during the melting process. Repeat this melting process 3 times.

[0069] (8) After the alloy is fully melted in step 7, the vacuum casting chamber is evacuated and the casting operation is performed. The molten alloy liquid is sucked into the water-cooled copper mold and solidified quickly by the vacuum negative pressure suction. The alloy ingot / rod is then cooled to room temperature to obtain the cast alloy ingot / rod.

[0070] (9) The cast alloy ingot / rod obtained in step 8 is placed into a heat treatment furnace and subjected to homogenization diffusion annealing at 1150°C under vacuum or high-purity argon protection for 6 hours. After the heat treatment is completed, the alloy is slowly cooled to room temperature in the furnace.

[0071] (10) After step 9 is completed, the oxide layer on the alloy surface is removed by grinding to obtain the hydrogen storage alloy sample of this application.

[0072] Scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS) analysis showed that the addition of nickel helped reduce the oxygen content in the alloy, with the oxygen content in the alloy of Comparative Example 1 significantly reduced to 2.41 wt%. This indicates that the addition of nickel significantly improved the oxidation resistance of the alloy.

[0073] The test results for this embodiment are as follows: Figure 1 Example 2 shows the hydrogen storage alloy Ti prepared in this application. 0.27 Zr 0.13 Mn 0.20 Cr 0.20 Fe 0.11 Cu 0.02 Ni 0. 07 The X-ray diffraction pattern of -8wt%ZrO2 shows that the alloy has a C14 Laves phase structure.

[0074] Figure 3 Ti, a hydrogen storage alloy 0.27 Zr 0.13 Mn 0.20 Cr 0.20 Fe 0.11 Cu 0.02 Ni 0.07 A scanning electron microscope backscattered electron image of -8wt%ZrO2 shows that zirconium oxide nanoparticles are uniformly dispersed within the Ti-Mn based C14Laves phase grains and at the grain boundaries.

[0075] Figure 5 The figure shows the hydrogenation curves of the hydrogen storage alloy prepared in Example 2 after vacuum degassing at 100°C for 30 minutes, followed by hydrogen absorption and desorption activation at 30°C and 5 MPa hydrogen pressure. The activation curves show that during the first hydrogenation, after an incubation period of approximately 30 minutes, the alloy began to absorb hydrogen significantly, reaching approximately 1.6 wt% after 90 minutes, which is about 86% of the alloy's maximum hydrogen storage capacity. Subsequently, vacuum dehydrogenation was performed for 20 minutes. After dehydrogenation, a second hydrogen absorption activation treatment was performed. The second hydrogenation curves show that after the first hydrogen absorption and desorption activation treatment, the alloy reached hydrogen saturation in approximately 30 minutes. After two hydrogen absorption and desorption activation treatments, the alloy was fully activated, absorbing hydrogen within 5 minutes. This alloy exhibits outstanding hydrogen absorption and desorption activation performance, mainly attributed to two factors: first, the addition of nickel enhances the alloy's oxidation resistance; second, the introduction of numerous heterogeneous interfaces by nano-zirconia increases hydrogen diffusion channels.

[0076] Figure 6 Ti, a hydrogen storage alloy 0.27 Zr 0.13 Mn 0.20 Cr 0.20 Fe 0.11 Cu 0.02 Ni 0.07After activation with -8wt% ZrO2, the hydrogen absorption and desorption cycle performance was tested at 25℃. After 30 hydrogen absorption and desorption cycles, the alloy maintained 98.9% of its reversible capacity. The alloy exhibits excellent hydrogen absorption and desorption cycle stability. Figure 3 Scanning electron microscopy analysis revealed that the alloy’s excellent hydrogen absorption and desorption cycle stability is mainly attributed to the alloy’s suitable grain size (1µm), the introduction of nano-zirconia which enhances the alloy’s resistance to hydrogen-induced powdering, and nickel which improves the alloy’s oxidation resistance.

[0077] Figure 7 Ti, a hydrogen storage alloy 0.27 Zr 0.13 Mn 0.20 Cr 0.20 Fe 0.11 Cu 0.02 Ni 0.07 The PCT curve of dehydrogenation of -8wt% ZrO2 at 25℃ shows that the alloy releases 1.85wt% of hydrogen in the pressure range of 0.07–5.5 MPa, with a hydrogen release plateau pressure of approximately 0.6 MPa. This alloy exhibits a moderate plateau pressure and high effective hydrogen storage capacity, which can well meet the requirements of solid-state hydrogen storage and supply systems such as fuel cell backup power supplies. It is a type of solid-state hydrogen storage alloy that combines easy activation, high capacity, and long-cycle stability. Furthermore, the alloy does not use rare and precious metals such as vanadium and rare earth elements, giving it a low-cost advantage.

[0078] Example 3 The alloy was prepared according to the composition of Example 3 in Table 1, and the hydrogen storage alloy Ti was prepared using an alloy preparation process similar to that of Examples 1 and 2. 0.25 Zr 0.10 Mn 0.20 Cr 0.25 Fe 0.10 Cu 0.03 Al 0.07 -15wt%ZrO2. Figure 1 Example 3 shows the X-ray diffraction pattern of the alloy, indicating that the alloy, like Examples 1 and 2, is an AB2 type C14 Laves phase.

[0079] The test results for this embodiment are as follows: Figure 4These are scanning electron microscope (SEM) images of the alloy. SEM observation and analysis show that the grain size of the alloy is approximately 2 µm. However, due to the increased addition of nano-zirconia to 15 wt%, more zirconia nanoparticles are clearly visible dispersed within the alloy grains and at the grain boundaries. Simultaneously, the grain boundary bonding is weaker than in Examples 1 and 2, exhibiting significant grain boundary separation. Energy dispersive spectroscopy (EDS) analysis shows that after adding aluminum, the oxygen content in the alloy is also reduced compared to Example 1 (5.50 wt%) (3.93 wt%), but slightly higher than the 2.41 wt% in Example 2. This indicates that adding aluminum can also improve the alloy's oxidation resistance, but the effect is not as significant as adding nickel.

[0080] Figure 10 The figure shows the hydrogen absorption kinetics curves of the hydrogen storage alloy sample prepared in Example 3 at low temperature (0°C) and pressure (2.5 MPa) after two hydrogen absorption and desorption activations. As can be seen from the second hydrogenation curve in the figure, the alloy can be activated after two hydrogen absorption and desorption activations, and hydrogen absorption can be completed within 2-3 minutes, indicating the alloy's outstanding hydrogen absorption and desorption activation performance.

[0081] Comparative Example 1 The only difference from Example 1 is that ZrO2 was not added. The test results are as follows: Figure 11 The hydrogen storage alloy prepared for Comparative Example 1 underwent hydrogen absorption and desorption activation at 30°C and 5 MPa hydrogen pressure after vacuum degassing at 100°C for 30 minutes. The activation curves in the figure show that after the first hydrogenation, an incubation period of approximately 120 minutes was required before the alloy began to absorb hydrogen significantly, and the hydrogen absorption reached approximately 0.25 wt% after 180 minutes. Subsequently, vacuum dehydrogenation was performed for 20 minutes. After dehydrogenation, a second hydrogen absorption activation treatment was performed. The second hydrogenation curve in the figure shows that after the first hydrogen absorption and desorption activation treatment, the alloy still took a long time to reach hydrogen saturation, requiring more than 180 minutes. After two hydrogen absorption and desorption activation treatments, the third hydrogenation curve in the figure shows that the alloy began to absorb hydrogen significantly after 10 minutes, and the later hydrogen absorption efficiency was significantly lower than that of the example. Compared with the example, the hydrogen absorption and desorption activation performance of this alloy is significantly insufficient.

[0082] Comparative Example 2 Chinese invention patent application with publication number CN 121406926A improves the composition and microstructure uniformity of the alloy by adding two rare earth elements, La and Ce, and repeatedly remelting and homogenizing at high temperature, thereby suppressing composition and microstructure segregation. Different metal elements such as Ti, Zr and Al are added as activators at different stages of alloy remelting. The maximum hydrogen storage capacity of the prepared alloy is 1.7 wt%.

[0083] It should be noted that: The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments under the concept of this application, and are not intended to limit them; those skilled in the art can make adaptive adjustments within the concept and protection scope of this application.

[0084] In addition, unless otherwise specified, the raw materials used may be commercially available products in the field or prepared by conventional methods in the field; that is, the reagents and instruments used in this embodiment do not specify the manufacturer or other information, and are all conventional products that can be purchased from the market.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0086] The specific embodiments of this application have been described above, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A Ti-Mn-based hydrogen storage alloy, characterized in that, The hydrogen storage alloy has a C14 Laves phase structure, and its components include Ti, Zr, Mn, Cr, Fe, Cu, Ni, Al and nano-zirconia. The general chemical formula of the hydrogen storage alloy is Ti a-x Zr x Mn y Cr z Fe b Cu c Ni d Al e -f wt% ZrO₂, wherein 0.35≤a≤0.4, 0.05≤x≤0.13, 0.2≤y≤0.4, 0.2≤z≤0.3, 0<b<0.15, 0<c≤0.1, 0≤d≤0.1, 0≤e≤0.1, and 0.6≤y+z+b+c+d+e≤0.7 is satisfied; Wherein, 5≤f≤15, and the mass fraction of nano-zirconia is 5-15% based on the total mass of the hydrogen storage alloy being 100%.

2. The Ti-Mn-based hydrogen storage alloy according to claim 1, characterized in that, The nano-zirconia is dispersed within the grains and at the grain boundaries of the hydrogen storage alloy.

3. The Ti-Mn-based hydrogen storage alloy according to claim 1, characterized in that, The oxygen content in the hydrogen storage alloy is no higher than 5.5 wt%.

4. The Ti-Mn-based hydrogen storage alloy according to claim 1, characterized in that, When the chemical formula contains Ni, the oxygen content in the hydrogen storage alloy is not higher than 2.41 wt%.

5. The Ti-Mn-based hydrogen storage alloy according to claim 1, characterized in that, The nano-zirconia is dispersed within the grains and at the grain boundaries of the hydrogen storage alloy. The grains of the hydrogen storage alloy are uniform in size and have a size of 1-3µm.

6. A method for preparing a Ti-Mn-based hydrogen storage alloy as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Weigh each elemental metal raw material Ti, Zr, Mn, Cr, Fe, Cu, Al, and Ni according to the general chemical formula of the hydrogen storage alloy, and weigh the amount of nano-zirconia in the formula. S2. Place all raw materials in a water-cooled copper crucible in the sample chamber of a vacuum non-consumable arc melting furnace according to a certain stacking method and melt them repeatedly for 3-5 times to obtain an alloy melt. S3. The alloy melt is rapidly cooled by suction casting to obtain a cast alloy; S4. The as-cast alloy is subjected to homogenization annealing at 980-1150°C for 6-24 hours, and then cooled to obtain the Ti-Mn-based hydrogen storage alloy.

7. The preparation method according to claim 6, characterized in that, In step S1, when weighing the elemental metal raw material, no more than 15 wt% Mn is added to compensate for smelting losses. Before weighing, the surface of the Ti raw material is treated to remove oxide scale, moisture, and adsorb air.

8. The preparation method according to claim 6, characterized in that, The purity of the metallic raw materials Ti, Zr, Mn, Cr, Fe, Cu, Al, and Ni is ≥99.8%; The nano-zirconia is a nanoscale powder.

9. The preparation method according to claim 6, characterized in that, In S2, Includes the following processes: The prepared raw materials were subjected to vacuum non-consumable arc melting: during sample loading, titanium, zirconium, and nickel were placed in the lower layer, chromium, iron, and copper in the upper layer, manganese and aluminum in the middle layer, and nano-zirconia was placed last; before melting, the vacuum was repeatedly evacuated more than 3 times, and the sample chamber was cleaned with high-purity argon; then the vacuum was evacuated again to ≤10. -3 After Pa, electric arc melting is carried out; before starting to melt the alloy sample, the titanium ingot in the water-cooled copper crucible in the center of the sample chamber is repeatedly melted 3 times or more, and the high-temperature titanium absorbs the residual oxygen impurity gas in the sample chamber before the sample is melted. In the initial stage of melting alloy samples, a small current ≤100A is used for pre-alloying to pre-alloy low-melting-point volatile alloy components, thereby reducing melting quality loss. Then, the melting current is gradually increased until all components are completely melted, and magnetic stirring is started. After the first melting is completed and the alloy solution has solidified, the alloy sample is flipped over for a second remelting. This process is repeated 3-5 times.

10. An application of a Ti-Mn-based hydrogen storage alloy as described in any one of claims 1 to 5, characterized in that, It can be used as a solid hydrogen storage medium for on-board hydrogen supply systems, backup power for hydrogen fuel cells, hydrogen storage, or hydrogen transportation devices.

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