An AB5-BCC composite hydrogen storage alloy and its preparation method

Abstract

This invention belongs to the field of hydrogen storage alloy technology and discloses an AB5-BCC composite hydrogen storage alloy and its preparation method. The composite hydrogen storage alloy comprises an AB5-type alloy and a BCC-type alloy, with the AB5-type alloy dispersed on the surface of the BCC-type alloy; the AB5-type alloy accounts for 2%-5% of the total weight of the composite hydrogen storage alloy. This invention improves the activation performance and anti-poisoning properties of the BCC hydrogen storage alloy by combining the AB5-type alloy and the BCC-type alloy to meet the needs of the developing solid-state hydrogen storage market.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage alloy technology, specifically relating to an AB5-BCC composite hydrogen storage alloy and its preparation method. Background Technology

[0002] Currently, vanadium-based hydrogen storage alloys exhibit extremely strong oxygen affinity due to their high vanadium content (typically >40%). Especially after being prepared into fine powder, their surfaces readily form dense and thick oxide layers, making the alloy activation process exceptionally difficult. In practical large-scale applications, both short-term exposure of the material to air and the introduction of impurity gases such as O2, CO, and CO2 into the hydrogen source can lead to poisoning of the alloy surface, thereby significantly weakening its reversible hydrogen storage capacity and hydrogen absorption / desorption kinetics. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides an AB5-BCC composite hydrogen storage alloy and its preparation method. By combining AB5-type alloy and BCC-type alloy to prepare a hydrogen storage alloy, the activation performance and anti-poisoning performance of the BCC hydrogen storage alloy are improved to meet the needs of the subsequent development of markets such as solid-state hydrogen storage.

[0004] The objective of this invention is achieved through the following technical solution: This invention provides an AB5-BCC composite hydrogen storage alloy, which includes an AB5 type alloy and a BCC type alloy, wherein the AB5 type alloy is dispersed on the surface of the BCC type alloy; the AB5 type alloy accounts for 2%-5% of the total weight of the composite hydrogen storage alloy.

[0005] In some embodiments, the general formula of the AB5 alloy is La. x Ni 60 Co y Mn z In the formula, x, y, and z represent weight percentages, and their numerical ranges are: 30≤x≤35, 3≤y≤7, and 2≤z≤4.

[0006] In some embodiments, the general formula of the BCC type alloy is Ti. a Cr b V c Al d Si e In the formula, a, b, c, d, and e represent weight percentages, and their numerical ranges are: 11≤a≤13, 18≤b≤22, 64≤c≤68, 1≤d≤2, and 0.5≤e≤1.5.

[0007] The present invention also provides a method for preparing the composite hydrogen storage alloy as described above, comprising: The AB5 type alloy and the BCC type alloy are crushed separately and then mixed to obtain a mixture. The mixture is then heat-treated to obtain the AB5-BCC composite hydrogen storage alloy.

[0008] In some embodiments, the BCC type alloy is crushed using a hammer crusher.

[0009] In some embodiments, the particle size of the BCC type alloy is <500 µm.

[0010] In some embodiments, the AB5 alloy is crushed using an air jet mill.

[0011] In some embodiments, the particle size of the AB5 alloy is <20 µm.

[0012] In some embodiments, the mixing method is to use a dual-cone mixer.

[0013] In some embodiments, the heat treatment temperature is 800-1000°C, and the heat treatment time is 0.5-6 hours.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention proposes an innovative strategy of combining AB5-type alloys with BCC-type alloys. By inducing the formation of a unique "island-like coating" microstructure, it effectively overcomes technical bottlenecks such as the difficulty in activating high-vanadium alloys and insufficient stability, while significantly reducing the preparation cost of hydrogen storage materials, achieving synergistic optimization of high performance and low cost. Attached Figure Description

[0015] Figure 1 This is a SEM image of the AB5-BCC composite hydrogen storage alloy obtained in Example 2 of the present invention; Figure 2 The image shows the XRD pattern of the AB5-BCC composite hydrogen storage alloy obtained in Example 2 of this invention. Detailed Implementation

[0016] This invention provides an AB5-BCC composite hydrogen storage alloy; the composite hydrogen storage alloy includes an AB5 type alloy and a BCC type alloy, wherein the AB5 type alloy is dispersed on the surface of the BCC type alloy; the AB5 type alloy accounts for 2%-5% of the total weight of the composite hydrogen storage alloy.

[0017] Among them, the general formula of AB5 type alloy is La. x Ni 60 Co y Mn zIn the formula, x, y, and z represent weight percentages, with the following numerical ranges: 30 ≤ x ≤ 35, 3 ≤ y ≤ 7, 2 ≤ z ≤ 4; the general formula for BCC type alloys is Ti. a Cr b V c Al d Si e In the formula, a, b, c, d, and e represent weight percentages, and their numerical ranges are: 11≤a≤13, 18≤b≤22, 64≤c≤68, 1≤d≤2, and 0.5≤e≤1.5.

[0018] It should be noted that the AB5 alloy accounts for 2%-5% of the total weight. When the weight is less than 2%, there are few composite bonding interfaces, and the improvement in activation performance is insufficient. When the weight is greater than 5%, there is too much AB5 alloy, and the hydrogen release decreases.

[0019] It should be noted that the AB5 type alloy was selected as La. x Ni 60 Co y Mn z The reason is that ordinary LaNi5 alloy has poor structural stability and poor cycle life during hydrogen absorption and desorption. The addition of Co and Mn can effectively improve the alloy performance of the material: the addition of Co can enhance the microstructural stability during hydrogen absorption and desorption and can form a protective layer on the alloy surface to prevent internal corrosion and pulverization of AB5 alloy; in addition, the combined effect of Co and Ni can optimize the diffusion channels of hydrogen atoms and the surface reaction rate; the addition of Mn can optimize the material kinetics and thermodynamic properties, regulate the plateau pressure, allow the alloy to work under milder conditions, and achieve the goal of cost reduction.

[0020] This invention also provides a method for preparing the composite hydrogen storage alloy as described above, comprising: Raw material pretreatment and preparation: The raw materials required for the preparation of BCC type alloy and AB5 type alloy are pretreated using a polishing machine and a dryer to remove oxides, impurities and moisture from the surface of the raw materials. The raw materials are vanadium-chromium alloy, titanium and chromium for BCC type alloy and lanthanum, nickel, cobalt and manganese for AB5 hydrogen storage alloy. The raw materials are weighed and prepared according to the general formula mass ratio of the BCC type alloy and AB5 type alloy to be prepared. Furnace preparation: Place the raw materials of BCC type alloy and AB5 type alloy into a 500 kg vacuum medium frequency induction furnace containing a zirconium oxide crucible, and turn on the power supply of the mechanical pump and the Roots pump; turn on the mechanical pump and the Roots pump to evacuate the vacuum. Oven drying: Connect the power supply to the 500 kg vacuum medium frequency induction melting furnace and cooling equipment, slowly increase the power to 250kW and maintain it for 5 minutes, remove the moisture and volatile impurities contained in the furnace, and then stop drying; Melting preparation: Continue vacuuming for no less than 30 minutes and reduce the furnace pressure to below 30 Pa. Introduce protective gas to perform at least two furnace cleaning cycles, with the furnace pressure dropping to below 30 Pa each time. After furnace cleaning, introduce protective gas. Melting: The heating power is increased from 10 kW / min to 400 kW. After maintaining the power for 5-8 minutes, the melting of raw materials in the melting furnace is observed. After the raw materials are completely melted, the power is maintained for another 3-8 minutes. The alloy melt is then poured from the melting furnace onto a rapid cooling strip spinning device with cold water flowing through it for rapid cooling to produce alloy sheets.

[0021] Annealing 1: The as-cast alloys obtained from the above melting process are subjected to annealing treatment to improve the uniformity of the microstructure and reduce the structural stress; among them, the BCC type alloy is subjected to rapid heat treatment at 1300℃ for 0.5-6 h, and the AB5 type alloy is subjected to heat treatment at 960℃ for 6 h. Crushing: BCC type alloy crushing adopts hammer crusher to crush into a maximum particle size of <500 μm; AB5 type alloy crushing adopts air jet mill crushing to crush into a maximum particle size of <20 μm. Mixing: After purifying the chamber with high-purity Ar (>99.99%) for 15 min, add 90%-99% (preferably 95%-98%) of BCC hydrogen storage alloy and 1%-10% (preferably 2%-5%) of AB5 alloy by weight to the double cone mixer, mix thoroughly for more than 30 min, and then cool for 30 min before removing.

[0022] Annealing 2: Anneal the mixture obtained above at 800-1000℃ for 0.5-6 h.

[0023] It should be noted that BCC alloys have high toughness and high hardness, and air jet mills cannot effectively crush the alloys, thus failing to form a good island-shaped coating structure. This application uses a rapid cooling belt throwing process combined with a hammer crusher preparation process and high-temperature heat treatment, which can effectively eliminate structural defects and internal stresses in the composite alloy, resulting in a composite alloy with more uniform composition, better coating effect, and superior performance.

[0024] The annealing temperature can be 800~1000℃, preferably 850~960℃, but not limited to 850℃, 860℃, 870℃, 880℃, 890℃, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, or 960℃. When the temperature is <850℃, the annealing treatment is insufficient, the phase interface is not effectively bonded, the bonding ability is weak, and the improvement in activation performance and stability is not obvious. When the annealing temperature is >960℃, the AB5 alloy enters a molten state, the interface bonding is too strong, the interface becomes blurred, the phase stability deteriorates, and the shell protection function is lost. The annealing time can be 0.5~6 h, preferably 0.5~3 h, but not limited to 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, or 3 h. When no annealing treatment is performed, the phase interface is not effectively bonded, and the improvement in activation performance and stability is not obvious. When the annealing time is >3 h, the phase interface bonding is strong, and the shell protection function is weakened.

[0025] In this application, the maximum particle size of the BCC alloy is controlled below 500 μm, and the maximum particle size of the AB5 alloy is controlled below 20 μm. The reason is that during hydrogen absorption, the lattice volume of the BCC alloy expands dramatically, with a volume expansion rate exceeding 10% during hydride formation. This dramatic volume change induces significant internal stress and generates numerous dislocations within the lattice. As the hydrogen absorption and desorption cycle continues, dislocations accumulate, leading to severe lattice distortion and ultimately severe pulverization and a sharp decline in capacity. Therefore, controlling the particle size below 500 μm is essentially a safety limit: if the particle size is too large, the stress generated by the dramatic volume change during hydrogen absorption and desorption cannot be effectively released, easily causing the alloy particles to crack from the inside, further exacerbating pulverization and accelerating performance degradation. The AB5 alloy, due to the addition of elements such as Co and Mn, exhibits significantly enhanced resistance to pulverization and corrosion, thus possessing excellent cycle stability. Its main performance bottleneck lies in kinetics. By refining the particles, the diffusion path of hydrogen atoms can be effectively shortened, thereby increasing the reaction rate.

[0026] The present invention will be further described in detail with reference to specific embodiments. The following embodiments can enable those skilled in the art to have a more comprehensive understanding of the present invention, but do not limit the present invention in any way.

[0027] Example 1: This embodiment provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0028] BCC type alloy design composition is Ti 13 Cr 19.7 V 65 Al 1.6 Si 0.7 The AB5 alloy is designed with a La composition. 31 Ni60 Co7Mn2, AB5 hydrogen storage alloy accounts for 2% of the total weight; The specific preparation method is as follows: Raw material pretreatment and preparation: The raw materials required for preparing BCC and AB5 alloys are pretreated using a polishing machine and a dryer to remove oxides, impurities, and moisture from the surface of the raw materials. The raw materials are vanadium-chromium alloy (V+Cr≥94wt%, Al+Si≤1.4wt%, Panzhihua Iron and Steel Group), titanium (≥99.6wt%), chromium (≥99.0wt%), and aluminum for BCC alloys, and lanthanum, nickel, cobalt, and manganese for AB5 hydrogen storage alloys. The raw materials are weighed and prepared according to the general formula mass ratio of the BCC and AB5 alloys to be prepared. Furnace preparation: Place the raw materials of BCC type alloy and AB5 type alloy into a 500 kg vacuum medium frequency induction furnace containing a zirconium oxide crucible, and turn on the power supply of the mechanical pump and the Roots pump; turn on the mechanical pump and the Roots pump to evacuate the vacuum. Oven drying: Connect the power supply to the 500 kg vacuum medium frequency induction melting furnace and cooling equipment, slowly increase the power to 250kW and maintain it for 5 minutes, remove the moisture and volatile impurities contained in the furnace, and then stop drying; Melting preparation: Continue vacuuming for no less than 30 minutes and reduce the furnace pressure to below 30 Pa. Introduce protective gas to perform at least two furnace cleaning cycles, with the furnace pressure dropping to below 30 Pa each time. After furnace cleaning, introduce protective gas. Melting: The heating power is increased from 10 kW / min to 400 kW and maintained at the power for 5 minutes. The melting of raw materials in the melting furnace is observed. After the raw materials are completely melted, the power is maintained for another 5 minutes. The alloy melt is then poured from the melting furnace onto a rapid cooling strip spinning device with cold water flowing through it for rapid cooling to produce alloy sheets.

[0029] Annealing 1: The as-cast alloys obtained from the above melting process are subjected to annealing treatment to improve the uniformity of the microstructure and reduce the structural stress; among them, the BCC type alloy is subjected to rapid heat treatment at 1300℃ for 0.5 h, and the AB5 type alloy is subjected to heat treatment at 960℃ for 6 h. Crushing: BCC type alloy crushing adopts hammer crusher to crush into a maximum particle size of <500 μm; AB5 type alloy crushing adopts air jet mill crushing to crush into a maximum particle size of <20 μm. Mixing: After purifying the chamber with high-purity Ar (>99.99%) for 15 min, add 95% of the BCC hydrogen storage alloy and 5% of the AB5 alloy by weight to the double cone mixer, mix thoroughly for more than 30 min, and then cool for 30 min before removing.

[0030] Annealing 2: The mixture obtained above was annealed at 960°C for 0.5 h.

[0031] Example 2: This embodiment provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0032] BCC type alloy design composition is Ti 12 Cr 21.4 V 64 Al 1.7 Si 0.9 The AB5 alloy is designed with a La composition. 33 Ni 60 Co4Mn3 and AB5 hydrogen storage alloy account for 3% of the total weight; the specific preparation method is the same as in Example 1, except that the annealing temperature for annealing 2 is 940℃, and other conditions are the same.

[0033] Example 3: This embodiment provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0034] BCC type alloy design composition is Ti 11 Cr 18.5 V 68 Al 1.5 Si 1.0 The AB5 alloy is designed with a La composition. 30 Ni 60 Co6Mn4 and AB5 hydrogen storage alloy account for 5% of the total weight; the specific preparation method is the same as in Example 1, except that the annealing temperature of 2 is 900℃, the annealing time is 1 h, and other conditions are the same.

[0035] Example 4: This embodiment provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0036] BCC type alloy design composition is Ti 13 Cr 19.3 V 65 Al 1.3 Si 1.4 The AB5 alloy is designed with a La composition. 35 Ni 60 Co3Mn2 and AB5 hydrogen storage alloy account for 3% of the total weight; the specific preparation method is the same as in Example 1, except that the annealing temperature of annealing 2 is 850℃, the annealing time is 3 h, and other conditions are the same.

[0037] Example 5: This embodiment provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0038] Compared to Example 1, the AB5 hydrogen storage alloy accounted for 4% of the total weight, with all other conditions remaining the same.

[0039] Comparative Example 1: This comparative example provides a hydrogen storage alloy and its preparation method.

[0040] Compared to Example 1, no AB5 hydrogen storage alloy was added, while all other conditions remained the same.

[0041] Comparative Example 2: This comparative example provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0042] Compared to Example 1, the AB5 hydrogen storage alloy accounted for 1% of the total weight, with all other conditions remaining the same.

[0043] Comparative Example 3: This comparative example provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0044] Compared to Example 1, the AB5 hydrogen storage alloy accounted for 10% of the total weight, with all other conditions remaining the same.

[0045] Comparative Example 4: This comparative example provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0046] Compared with Example 1, the annealing temperature for Example 2 was 800°C, the annealing time was 0.5 h, and other conditions were the same.

[0047] Comparative Example 5: This comparative example provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0048] Compared with Example 1, the annealing temperature for Example 2 was 1000°C, the annealing time was 0.5 h, and other conditions were the same.

[0049] Comparative Example 6: This comparative example provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0050] Compared to Example 1, the annealing process 2 was not performed, while other conditions remained the same.

[0051] Comparative Example 7: This comparative example provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0052] Compared with Example 1, the annealing temperature for Example 2 was 800°C, the annealing time was 6 hours, and other conditions were the same.

[0053] Comparative Example 8: This comparative example provides an AB5-BCC composite hydrogen storage alloy and its preparation method.

[0054] Compared to Example 1, the AB5 hydrogen storage alloy accounted for 8% of the total weight, with all other conditions remaining the same.

[0055] The hydrogen storage performance of the examples and comparative examples was tested using the following methods: After annealing the sample for 2 days, expose it to air and store it for 3 days. Then, take 1 g of the sample and put it into the sample chamber. After activation at 100-400℃, under pure hydrogen gas at 10 MPa, absorb hydrogen at 2℃ and release hydrogen at 50℃ to obtain the amount of hydrogen released. Continue to evacuate under vacuum for 30 min, then introduce hydrogen gas containing 100 ppm to 5 MPa, absorb hydrogen at 2℃ and release hydrogen at 50℃. After the hydrogen release is completed, continue to evacuate under vacuum for 30 min. Repeat this cycle 10 times to conduct an air poisoning test.

[0056] The formula for calculating the attenuation rate (%) is η=(C1-C 10 ) / C1×100%, where C1 is the amount of hydrogen absorbed in the first absorption, C 10 This is the amount of hydrogen absorbed during the 10th absorption.

[0057] The test results are shown in Table 1: Table 1

[0058] The composite hydrogen storage alloy obtained in Example 2 was analyzed by scanning electron microscopy (SEM, Hitachi SU8000 cold field emission scanning electron microscope) and X-ray diffraction (XRD, Bruker D8 ADVANCE X-ray diffractometer). The results are as follows: Figure 1 and Figure 2 As shown, it is confirmed that small-particle AB5 alloy adheres to the surface of BCC alloy and forms a bonding phenomenon. The phase structure is mainly BCC phase, and AB5 phase structure can be detected, indicating that AB5 alloy effectively coats BCC alloy.

[0059] The properties of the alloys obtained in Examples 1-5 and Comparative Examples 1, 2, 3, and 8 were compared, and the results are shown in Table 1. The AB5 hydrogen storage alloy weight ratio between 2% and 5% can effectively reduce the activation temperature of the BCC hydrogen storage alloy and improve the material stability. This is mainly because the AB5 hydrogen storage alloy is dispersed on the surface of the BCC hydrogen storage alloy as a catalytic site and a protective layer, which improves the activation performance and stability of the BCC hydrogen storage alloy.

[0060] Comparison of the properties of the alloys obtained in Examples 1, 2, 3, and 4 and Comparative Examples 4, 5, and 6 revealed that annealing treatment can effectively combine the AB5 hydrogen storage alloy and the BCC hydrogen storage alloy, forming a stable island-like coating structure, thus protecting and improving the performance of the BCC hydrogen storage alloy. The suitable temperature is controlled between 850-960℃. If the temperature is too low, the interfacial bonding will be insufficient, resulting in poor shell protection, activation performance, and stability. If the temperature is too high, the interfacial bonding will be too strong, disrupting the stability of the interfacial phase structure, leading to poor activation performance and stability.

[0061] Comparing the properties of the alloys obtained in Examples 2-4 and Comparative Examples 6 and 7, it can be seen that the suitable annealing time is 0.5-3 h. The longer the time, the stronger the bonding at the phase interface will be. Excessive bonding will also lead to poor activation performance and stability.

[0062] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. An AB5-BCC composite hydrogen storage alloy, characterized in that, The composite hydrogen storage alloy includes AB5 type alloy and BCC type alloy, with the AB5 type alloy dispersed on the surface of the BCC type alloy; the AB5 type alloy accounts for 2%-5% of the total weight of the composite hydrogen storage alloy.

2. The composite hydrogen storage alloy according to claim 1, characterized in that, The general formula of the AB5 type alloy is La. x Ni 60 Co y Mn z In the formula, x, y, and z represent weight percentages, and their numerical ranges are: 30≤x≤35, 3≤y≤7, and 2≤z≤4.

3. The composite hydrogen storage alloy according to claim 1, characterized in that, The general formula of the BCC type alloy is Ti. a Cr b V c Al d Si e In the formula, a, b, c, d, and e represent weight percentages, and their numerical ranges are: 11≤a≤13, 18≤b≤22, 64≤c≤68, 1≤d≤2, and 0.5≤e≤1.

5.

4. A method for preparing a composite hydrogen storage alloy as described in any one of claims 1-3, characterized in that, include: The AB5 type alloy and the BCC type alloy are crushed separately and then mixed to obtain a mixture. The mixture is then heat-treated to obtain the AB5-BCC composite hydrogen storage alloy.

5. The preparation method according to claim 4, characterized in that, The BCC type alloy is crushed using a hammer crusher.

6. The preparation method according to claim 4, characterized in that, The particle size of the BCC type alloy is <500 µm.

7. The preparation method according to claim 4, characterized in that, The AB5 alloy is crushed using an air jet mill.

8. The preparation method according to claim 4, characterized in that, The particle size of the AB5 alloy is <20 µm.

9. The preparation method according to claim 4, characterized in that, The mixing method involves using a double-cone mixer.

10. The preparation method according to claim 4, characterized in that, The heat treatment temperature is 800-1000℃, and the heat treatment time is 0.5-6 h.

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