Vanadium-based hydrogen storage alloy capable of being activated at room temperature, preparation method of vanadium-based hydrogen storage alloy and application of Sm

Abstract

The invention discloses a vanadium-based hydrogen storage alloy capable of being activated at room temperature, a preparation method of the vanadium-based hydrogen storage alloy and application of Sm, belongs to the technical field of hydrogen storage materials, and aims at solving the technical problems that an existing vanadium-based hydrogen storage alloy is high in activation temperature and long in activation time. The vanadium-based hydrogen storage alloy capable of being activated at room temperature provided by the invention has a general formula of V < x > Ti < y > Cr < z > Fe < a + b wt% S < m >, x + y + z + a = 10, 7 < = x < = 8, 0.7 < = y < = 1.4, 1.0 < = z < = 1.6, 0.2 < = a < = 0.3, 0.005 < = b < = 0.010; wherein x, y, z and a are atomic ratios, and b is the mass percent of Sm in the vanadium-based hydrogen storage alloy. After the vanadium-based hydrogen storage alloy is vacuumized at the temperature of 40 DEG C for 3000 seconds, the vanadium-based hydrogen storage alloy absorbs hydrogen once under the hydrogen conditions of 40 DEG C and 8 MPa, and the vanadium-based hydrogen storage alloy can be completely activated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen storage alloy materials, and particularly relates to a vanadium-based hydrogen storage alloy activatable at room temperature, a preparation method thereof and a use of Sm. BACKGROUND

[0002] Hydrogen energy is a kind of secondary energy with abundant sources, green and low carbon, and wide application, and is gradually becoming one of important carriers for global energy transformation development.

[0003] Due to the physical and chemical characteristics of low density and high activity, the development of hydrogen gas is limited in the storage and transportation link. Solid-state hydrogen storage is a high-efficiency and safe storage and transportation mode due to its high safety, high bulk density and excellent hydrogen absorption and desorption performance. The hydrogen storage material is the key to the solid-state hydrogen storage technology. The vanadium-based hydrogen storage alloy is one of the most promising hydrogen storage materials due to its high hydrogen storage capacity, room temperature hydrogen absorption and desorption temperature, and good hydrogen absorption and desorption characteristics.

[0004] However, the vanadium and titanium elements account for a high proportion in the vanadium-based hydrogen storage alloy, and a dense oxide layer exists on the surface of the alloy, which causes the problems of high activation temperature and long activation time of the alloy. Generally, the vanadium-based hydrogen storage alloy needs an activation temperature of 400 DEG C and an activation time of more than 1 hour, and it takes 2-3 times to completely activate, which causes difficulties in its practical application. Therefore, it is very important for the practical application of solid-state hydrogen storage to develop a vanadium-based alloy with low activation temperature, high hydrogen absorption rate and high capacity. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide a vanadium-based hydrogen storage alloy activatable at room temperature, a preparation method thereof and a use of Sm, so as to solve the problems of high activation temperature and long activation time of the existing vanadium-based hydrogen storage alloy.

[0006] The purpose of the present application is mainly realized through the following technical solutions: On the one hand, the present application provides a vanadium-based hydrogen storage alloy activatable at room temperature, the general formula of which is V x Ti y Cr z Fe a +bwt%Sm; and the general formula satisfies the condition: x+y+z+a=10, 7<=x<=8, 0.7<=y<=1.4, 1.0<=z<=1.6, 0.2<=a<=0.3, 0.005<=b<=0.010. In the general formula of the vanadium-based hydrogen storage alloy, x, y, z and a are atomic ratios, and b is the mass percentage of Sm in the vanadium-based hydrogen storage alloy.

[0007] In a possible design, the general formula of the vanadium-based hydrogen storage alloy is V x Ti y Cr z Fea +bwt%Sm; and the general formula satisfies the following conditions: x+y+z+a=10, 7≤x≤7.5, 0.7≤y≤1.2, 1.0≤z≤1.6, 0.2≤a≤0.3, 0.008≤b≤0.01; where x, y, z, and a are atomic ratios, and b is the mass percentage of Sm in the vanadium-based hydrogen storage alloy.

[0008] On the other hand, the present invention also provides a method for preparing a room-temperature-activated vanadium-based hydrogen storage alloy, for preparing the above-mentioned room-temperature-activated vanadium-based hydrogen storage alloy; the preparation method includes the following steps: Step 1: Calculate and weigh each raw material according to the general formula and additional addition amount of vanadium-based hydrogen storage alloy for batching. Step 2: Perform a single smelting process to prepare a master alloy that does not contain Sm elements; V, Ti, Cr, and Fe raw materials were weighed according to the general formula ratio and placed in a water-cooled copper crucible. The furnace was evacuated and filled with inert argon gas for melting. After melting, the alloy ingot was cooled and turned over, and then melted again to obtain a master alloy without Sm. Step 3: Perform secondary smelting to prepare a vanadium-based hydrogen storage alloy containing Sm; Step 3 includes: Step 31: Cool the Sm-free master alloy to 60°C or below. After opening the furnace, add the prepared Sm raw material to the Sm-free master alloy. Evacuate the furnace and fill it with inert protective gas argon. Repeat the evacuation and argon filling process three times to exhaust the air in the furnace. Step 32: Perform the arc initiation operation; Step 33: After successful arc ignition, smelting is carried out to finally obtain a vanadium-based hydrogen storage alloy containing Sm.

[0009] Furthermore, in step 1, the Sm element is given an additional 200% weight.

[0010] Furthermore, in step 1, the purity of the raw materials V, Ti, Cr, Fe, and Sm in the vanadium-based hydrogen storage alloy all reaches over 99%.

[0011] Furthermore, step 2 includes the following sub-steps: Step 21: Place the prepared V, Ti, Cr, and Fe raw materials into a water-cooled copper crucible, and then place the water-cooled copper crucible into an electric arc induction melting furnace; evacuate the electric arc induction melting furnace to 10°C. -1 ~10 -3 Pa, then fill with inert protective gas until the vacuum pressure gauge shows -0.04~-0.06 MPa.

[0012] Furthermore, in step 21, the vacuuming and inert gas filling operations are repeated three times to completely purge the air from the furnace.

[0013] Furthermore, step 2 above also includes: step 22, adjusting the distance between the arc gun and the upper end of the sample to 3~5 mm before performing the arc ignition operation.

[0014] Furthermore, step 2 above also includes: step 23, after successful arc ignition, increase the current to 180 A and raise the arc gun to a distance of 15~25 mm from the top of the sample, each melting lasts for 3~5 minutes.

[0015] Furthermore, in step 23, after the single melting is completed, the alloy ingot is cooled, flipped 180°, and melted again to obtain a master alloy that does not contain Sm elements.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: (1) In the vanadium-based hydrogen storage alloy of the present invention, the general formula is V x Ti y Cr z Fe a In the +bwt%Sm alloy, x is controlled within the range of 7-8 to maintain the good hydrogen absorption / desorption plateau characteristics and cycle stability of the hydrogen storage alloy. The contents of y and z are controlled within the above range to regulate the cell volume of the alloy and maintain the hydrogen absorption / desorption plateau pressure between 0.5 and 2 MPa to meet its application requirements in the field of solid-state hydrogen storage. The value range of a is to reduce raw material costs and improve cycle performance without significantly reducing the hydrogen storage capacity of the alloy. The range of b is set to effectively improve the activation performance of the alloy by using trace amounts of Sm elements without affecting the hydrogen storage capacity and hydrogen absorption / desorption plateau pressure, thereby significantly reducing its activation temperature and activation times.

[0017] (2) This invention can obtain a vanadium-based hydrogen storage alloy that can be activated at room temperature and has a high capacity by adding trace amounts of Sm. The trace amounts of Sm can purify, remove impurities and oxygen from the raw materials during the preparation process, which is beneficial to the cycle stability of the alloy. At the same time, the rare earth elements form uniform rare earth compounds in the alloy matrix, which can quickly absorb hydrogen and reduce the activation temperature of the alloy. The alloy can be activated and absorb hydrogen at 40°C.

[0018] (3) The high-capacity vanadium-based hydrogen storage alloy provided by the present invention has a fast hydrogen absorption rate, a high hydrogen storage capacity, and excellent cycle stability.

[0019] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0020] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. Figure 1 Microstructure diagram of the Sm-containing vanadium-based hydrogen storage alloy of the present invention; Figure 2 Activation curve of the Sm-containing vanadium-based hydrogen storage alloy of the present invention. Detailed Implementation

[0021] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0022] On one hand, the present invention provides a room-temperature-activated vanadium-based hydrogen storage alloy, wherein the general formula of the vanadium-based hydrogen storage alloy is V x Ti y Cr z Fe a +bwt%Sm; and the general formula satisfies the following conditions: x+y+z+a=10, 7≤x≤8, 0.7≤y≤1.4, 1.0≤z≤1.6, 0.2≤a≤0.3, 0.005≤b≤0.010; In the above general formula for vanadium-based hydrogen storage alloys, x is controlled within the range of 7-8 to maintain the good hydrogen absorption / desorption plateau characteristics and cycle stability of the hydrogen storage alloy; the contents of y and z are controlled within the above range to regulate the cell volume of the alloy, so that the hydrogen absorption / desorption plateau pressure of the alloy is maintained between 0.5 and 2 MPa, in order to meet its application requirements in the field of solid-state hydrogen storage; the value range of a is to reduce the raw material cost and improve the cycle performance without significantly reducing the hydrogen storage capacity of the alloy; the range of b is set to effectively improve the activation performance of the alloy by using trace amounts of Sm elements without affecting the hydrogen storage capacity and hydrogen absorption / desorption plateau pressure, thereby significantly reducing its activation temperature and activation times.

[0023] In the above general formula for vanadium-based hydrogen storage alloys, the proportions x, y, z, and a are atomic ratios, and b is the mass percentage of Sm in the vanadium-based hydrogen storage alloy.

[0024] In the above general formula for vanadium-based hydrogen storage alloys, V is the main hydrogen-absorbing element, maintaining the crystal structure and basic hydrogen storage performance of the alloy BCC.

[0025] Ti and Cr can be infinitely dissolved in V, maintaining the BCC crystal structure and thus increasing the hydrogen absorption rate of the alloy. The ratio of Ti to Cr can synergistically regulate the cell volume of V-based hydrogen storage alloys and adjust their hydrogen absorption / desorption plateau pressures to meet the application requirements of solid-state hydrogen storage. Simultaneously, the addition of Ti and Cr can reduce the amount of V required, lowering raw material costs.

[0026] The role of Fe is to regulate the hydrogen absorption and desorption plateau characteristics of the alloy, reduce the alloy hysteresis coefficient, help improve the hydrogen desorption efficiency of the alloy, and at the same time effectively reduce the raw material cost.

[0027] The synergistic effect of each element and trace Sm is as follows: Sm cannot be dissolved in V-based hydrogen storage alloys. During the preparation process, it combines with impurity elements and oxygen to form rare earth oxide Sm2O3, which plays a role in purifying and removing oxygen from the hydrogen storage alloy. At the same time, the rare earth oxide is dispersed in the matrix, which can reduce the activation energy of the alloy, thereby achieving the effect of reducing the activation temperature and the number of activations.

[0028] Compared with existing technologies, this invention obtains a hydrogen storage alloy that can be activated at room temperature and has a high hydrogen storage capacity by adding trace amounts of samarium (Sm). Specifically: (1) Purification effect of trace Sm elements: During the alloy preparation process, trace Sm elements can purify the raw materials, removing impurities and oxygen elements. This helps to optimize the internal structure of the alloy, improve its purity, and thus enhance its cycle stability.

[0029] (2) The role of trace amounts of Sm in lowering the activation temperature and accelerating hydrogen absorption: As a rare earth element, Sm can form uniformly distributed rare earth compounds in the alloy matrix. The presence of these compounds can effectively lower the activation energy barrier of the alloy, promote the adsorption and dissociation of hydrogen molecules on the alloy surface, and accelerate the diffusion rate of hydrogen atoms inside the alloy. This enables the alloy to not only achieve rapid hydrogen absorption, but also significantly lowers the activation temperature, allowing activation and hydrogen absorption to be completed at 40℃.

[0030] (3) The effect of trace Sm elements on improving the surface oxide layer: By introducing Sm and the rare earth oxide Sm2O3 formed therefrom, the formation process and properties of the dense oxide layer on the surface of vanadium-based alloys can be effectively alleviated or changed, thereby reducing the resistance of hydrogen to entering the alloy interior, so that the alloy can be fully activated at a lower temperature (40℃) and fewer activation times (1 hydrogen absorption).

[0031] The general formula for the above-mentioned vanadium-based hydrogen storage alloys is V x Ti y Crz Fe a +bwt%Sm; and the general formula satisfies the following conditions: x+y+z+a=10, 7≤x≤7.5, 0.7≤y≤1.2, 1.0≤z≤1.6, 0.2≤a≤0.3, 0.008≤b≤0.01; the proportions x, y, z, and a are atomic ratios, and b is the mass percentage of Sm in the vanadium-based hydrogen storage alloy.

[0032] The aforementioned vanadium-based hydrogen storage alloy, after being vacuumed at 40°C for 3000 seconds, was fully activated after one hydrogen absorption cycle under hydrogen conditions of 40°C and 8 MPa. The mechanism is as follows: Firstly, during the preparation process, Sm can purify and remove impurities from the alloy, reducing the dense oxide layer on the alloy surface and lowering the resistance of the hydrogen absorption channels. Secondly, the formed rare earth oxide Sm₂O₃ and the matrix are two different types of substances with significantly different physical properties, including marked differences in strength and hardness, resulting in a weak bond between the rare earth oxide Sm₂O₃ and the matrix (e.g., ...). Figure 1 As shown, rare earth oxides easily form gaps and cracks at the interface with the matrix. These gaps and cracks are the initial hydrogen atom diffusion channels. After these cracks absorb hydrogen and expand, they form new extended cracks, forming secondary diffusion channels, which enables the alloy to be activated in one step.

[0033] When the above-mentioned vanadium-based hydrogen storage alloy absorbs hydrogen at 40℃ and 8MPa, the time required to reach 90% of the maximum hydrogen storage capacity is <300s, and the maximum hydrogen storage capacity is >3.52wt%.

[0034] The aforementioned vanadium-based hydrogen storage alloy absorbs hydrogen under hydrogen conditions of 10℃ and 8MPa, and can effectively release hydrogen (>2.3wt%) at 60℃ and above 0.1 MPa.

[0035] The above-mentioned vanadium-based hydrogen storage alloy has a capacity retention rate of >90% after 100 cycles.

[0036] Preferably, the above-mentioned vanadium-based hydrogen storage alloy is V7Ti. 1.1 Cr 1.6 Fe 0.3 +0.005wt%Sm.

[0037] Preferably, the above-mentioned vanadium-based hydrogen storage alloy is V 7.2 Ti 1.0 Cr 1.6 Fe 0.2 +0.006wt%Sm.

[0038] Preferably, the above-mentioned vanadium-based hydrogen storage alloy is V 7.5 Ti 0.9 Cr 1.3 Fe 0.3 +0.008wt%Sm.

[0039] Preferably, the above-mentioned vanadium-based hydrogen storage alloy is V8Ti. 0.75 Cr 1.05 Fe 0.2 +0.008wt%Sm.

[0040] This invention also provides a method for preparing a room-temperature-activated vanadium-based hydrogen storage alloy, which includes the following steps: Step 1: Prepare the ingredients; Calculate and weigh each raw material according to the general formula and additional addition amount of vanadium-based hydrogen storage alloy.

[0041] During the batching stage, considering the heat loss and volatilization of Sm during the smelting process, an additional 200% by weight of Sm element is added to ensure the Sm content in the final alloy.

[0042] In step 1 above, the purity of the raw materials V, Ti, Cr, Fe, and Sm in the general formula of vanadium-based hydrogen storage alloys all reach over 99%.

[0043] It's important to explain that using high-purity raw materials effectively reduces the introduction of impurities into the alloy, preventing them from forming harmful phases or defects within the alloy and thus ensuring the uniformity and purity of the alloy's microstructure. This is crucial for Sm to exert its purifying effect, lower the activation energy barrier, and improve cycle stability, helping the alloy achieve lower activation temperatures and faster hydrogen absorption rates. If vanadium with a purity below 99% is used in alloy preparation, it may contain impurities such as oxygen and nitrogen. These impurities may react with active elements such as vanadium and titanium during smelting to form stable oxides or nitrides. These compounds hinder hydrogen adsorption and diffusion, leading to difficult alloy activation and performance degradation. Even with the addition of Sm, the optimization effect will be significantly reduced. Therefore, high-purity raw materials are key to ensuring high alloy performance.

[0044] Step 2: Perform a single smelting process to prepare a master alloy that does not contain Sm elements; The raw materials V, Ti, Cr, and Fe are weighed according to the general formula ratio and placed in a water-cooled copper crucible. The crucible is then evacuated and filled with an inert gas (e.g., argon) in an arc induction melting furnace before melting. After melting, the ingot is cooled, turned over, and melted again to obtain a master alloy free of Sm. Specifically, the following sub-steps are included: Step 21: Place the prepared V, Ti, Cr, and Fe raw materials into a water-cooled copper crucible, then place the water-cooled copper crucible in an electric arc induction melting furnace, and evacuate the furnace to 10°C. -1 ~10 -3 Pa (e.g. 5 × 10) -3Then, fill the furnace with an inert protective gas (e.g., argon) until the vacuum pressure gauge shows -0.04 to -0.06 MPa (e.g., -0.05 MPa), and repeat the vacuuming and argon filling operation three times to completely remove the air from the furnace.

[0045] Step 22: Adjust the distance between the arc gun and the upper end of the sample to 3-5 mm before starting the arc. Step 23: After successful arc ignition, gradually increase the current to 180 A and raise the arc gun to a distance of 15-25 mm from the top of the sample. Each melting process lasts 3-5 minutes. After each melting, allow the alloy ingot to cool, then flip it 180° and melt it again to obtain a master alloy free of Sm. Flipping the alloy ingot and melting it again ensures the uniformity of the master alloy composition.

[0046] Step 3: Perform secondary smelting to prepare vanadium-based hydrogen storage alloy containing Sm element; Step 31: Cool the Sm-free master alloy to 60°C or below. After opening the furnace, add the prepared Sm raw material to the Sm-free master alloy, and evacuate the furnace to 10°C. -1 ~10 -3 Pa, (e.g., vacuumed to 5 × 10 Pa) -3 (Pa) Fill the furnace with inert protective gas argon until the vacuum pressure gauge reaches -0.04 to -0.06 MPa (e.g., fill to -0.05 MPa). Repeat the vacuuming and argon filling process three times to purge the air from the furnace. Then fill the furnace with argon until the vacuum pressure gauge reaches -0.04 to -0.06 MPa (e.g., fill to -0.05 MPa). Step 32: Adjust the distance between the arc gun and the upper end of the sample to 3-5 mm before starting the arc. Step 33: After successful arc ignition, gradually increase the current to 180 A and slowly raise the arc gun so that the distance between the arc gun and the upper part of the sample reaches 15~25 mm; each melting lasts for 3~5 minutes. After a single melting is completed, wait for the alloy ingot to cool, flip it 180°, and melt it again to finally obtain a vanadium-based hydrogen storage alloy containing Sm.

[0047] Compared with the prior art, the preparation method of the present invention has the following beneficial effects: (1) The preparation method of the present invention involves step-by-step melting. First, a master alloy without Sm element is prepared, and then Sm element is added for secondary melting. This method can better ensure the uniformity and stability of the alloy composition. Step-by-step melting can avoid excessive volatilization of Sm element or unnecessary reaction with other elements during the early melting process, ensuring that Sm element can play its role in purification, impurity removal, deoxygenation and reduction of activation temperature at the appropriate stage.

[0048] (2) In preparing the Sm-free master alloy, the present invention involves multiple vacuuming and inert gas filling operations, which can completely remove air from the furnace and reduce the influence of oxygen and impurities on the alloy, laying the foundation for subsequent performance improvement of the alloy. Moreover, in the process of arc melting, precise control of the distance between the arc gun and the sample, the current magnitude, and the melting time helps to make the alloy composition more uniform and improve the quality of the master alloy.

[0049] (3) When adding Sm element in the secondary melting process, the present invention also performs multiple vacuuming and inert gas filling operations to further ensure the purity of the melting environment. Manually and slowly increasing the parameters of the arc gun and controlling the current can enable Sm element to be better integrated into the master alloy and form a uniform distribution, so as to give full play to its optimization effect on alloy performance.

[0050] (4) The preparation method of the present invention is relatively simple to operate, does not require complex equipment and processes, reduces production costs, improves production efficiency, and is conducive to the large-scale industrial production of the room-temperature activated vanadium-based hydrogen storage alloy.

[0051] Furthermore, this invention also provides an application of Sm in reducing the activation temperature and hydrogen absorption rate of vanadium-based hydrogen storage alloys.

[0052] This invention applies the principle and preparation method of the vanadium-based hydrogen storage alloy that can be activated at room temperature. By adding a trace amount of Sm element to the alloy, and utilizing its synergistic effect with other elements, the activation temperature of the alloy and the hydrogen absorption rate are reduced.

[0053] Example 1 The room-temperature activated vanadium-based hydrogen storage alloy used in this embodiment has the general formula V7Ti. 1.1 Cr 1.6 Fe 0.3 +0.005wt%Sm, as shown in Table 1 below, its preparation process includes the following steps: Step 1: Calculate and weigh each raw material according to the general formula and additional addition amount of vanadium-based hydrogen storage alloy for batching; considering the heat loss and volatilization of Sm during the smelting process, add an additional 200% by weight of Sm element to ensure the Sm content in the final alloy.

[0054] In the general formula of vanadium-based hydrogen storage alloys, the purity of raw materials V, Ti, Cr, Fe, and Sm all reach over 99%.

[0055] Step 2: Perform a single smelting process to prepare a master alloy that does not contain Sm elements; The raw materials V, Ti, Cr, and Fe are weighed according to the general formula ratio, and then placed in a water-cooled copper crucible. The crucible is then evacuated and filled with inert argon gas in an arc induction melting furnace for melting. After melting, the ingot is cooled, turned over, and melted again to obtain a master alloy free of Sm. The specific steps include the following: Step 21: Place the prepared V, Ti, Cr, and Fe raw materials into a water-cooled copper crucible, then place the water-cooled copper crucible in an electric arc induction melting furnace, and evacuate the furnace to 5×10⁻⁶ ℃. -1 Pa, then fill with inert protective gas argon until the vacuum pressure gauge shows -0.04 MPa, and repeat the vacuuming and argon filling operation three times to completely remove the air from the furnace.

[0056] Step 22: Adjust the distance between the arc gun and the upper end of the sample to 3 mm before starting the arc. Step 23: After successful arc ignition, gradually increase the current to 180 A and raise the arc gun to a distance of 18 mm from the top of the sample. Each melting lasts for 3 minutes. After a single melting is completed, wait for the alloy ingot to cool, flip it 180°, and melt it again to obtain a master alloy without Sm elements.

[0057] Step 3: Perform secondary smelting to prepare vanadium-based hydrogen storage alloy containing Sm element; Step 31: Cool the Sm-free master alloy to 60°C or below. After opening the furnace, add the prepared Sm raw material to the Sm-free master alloy, and evacuate the furnace to 5×10⁻⁶ ℃. -1 Pa, fill with inert protective gas argon until the vacuum pressure gauge reaches -0.04MPa, repeat the vacuuming and argon filling process three times to purge the air from the furnace, and fill with argon until the vacuum pressure gauge reaches -0.04MPa; Step 32: Adjust the distance between the arc gun and the upper end of the sample to 3 mm before starting the arc. Step 33: After successful arc ignition, gradually increase the current to 180 A and slowly raise the arc gun so that the distance between the arc gun and the upper end of the sample reaches 18 mm; each melting lasts for 3 minutes. After a single melting is completed, wait for the alloy ingot to cool, flip it 180°, and melt it again to finally obtain a vanadium-based hydrogen storage alloy containing Sm.

[0058] The performance of the Sm-containing vanadium-based hydrogen storage alloy prepared in this embodiment was tested, and the results are shown in Table 2 below.

[0059] Example 2 The general formula for the room-temperature activated vanadium-based hydrogen storage alloy used in this embodiment is V. 7.2 Ti 1.0 Cr 1.6 Fe 0.2+0.006wt%Sm, as shown in Table 1 below, its preparation process includes the following steps: Step 1: Calculate and weigh each raw material according to the general formula and additional addition amount of vanadium-based hydrogen storage alloy for batching; considering the heat loss and volatilization of Sm during the smelting process, add an additional 200% by weight of Sm element to ensure the Sm content in the final alloy.

[0060] In the general formula of vanadium-based hydrogen storage alloys, the purity of raw materials V, Ti, Cr, Fe, and Sm all reach over 99%.

[0061] Step 2: Perform a single smelting process to prepare a master alloy that does not contain Sm elements; The raw materials V, Ti, Cr, and Fe are weighed according to the general formula ratio, and then placed in a water-cooled copper crucible. The crucible is then evacuated and filled with inert argon gas in an arc induction melting furnace for melting. After melting, the ingot is cooled, turned over, and melted again to obtain a master alloy free of Sm. The specific steps include the following: Step 21: Place the prepared V, Ti, Cr, and Fe raw materials into a water-cooled copper crucible, then place the water-cooled copper crucible in an electric arc induction melting furnace, and evacuate the furnace to a vacuum of 9×10⁻⁶. -2 Pa, then fill with inert protective gas argon until the vacuum pressure gauge shows -0.05MPa, and repeat the vacuuming and argon filling operation three times to completely remove the air from the furnace.

[0062] Step 22: Adjust the distance between the arc gun and the upper end of the sample to 4 mm before starting the arc. Step 23: After successful arc ignition, gradually increase the current to 180 A and raise the arc gun to a distance of 23 mm from the top of the sample. Each melting lasts for 5 minutes. After a single melting is completed, wait for the alloy ingot to cool, flip it 180°, and melt it again to obtain a master alloy without Sm elements.

[0063] Step 3: Perform secondary smelting to prepare vanadium-based hydrogen storage alloy containing Sm element; Step 31: Cool the Sm-free master alloy to 60°C or below. After opening the furnace, add the prepared Sm raw material to the Sm-free master alloy, and evacuate the furnace to 9×10⁻⁶ ℃. -2 Pa, fill with inert protective gas argon until the vacuum pressure gauge reaches -0.05 MPa, repeat the vacuuming and argon filling process three times to purge the air from the furnace, and fill with argon until the vacuum pressure gauge reaches -0.05 MPa; Step 32: Adjust the distance between the arc gun and the upper end of the sample to 4 mm before starting the arc. Step 33: After successful arc ignition, gradually increase the current to 180 A and slowly raise the arc gun so that the distance between the arc gun and the upper end of the sample reaches 23 mm; each melting lasts for 5 minutes. After a single melting is completed, wait for the alloy ingot to cool, flip it 180°, and melt it again to finally obtain a vanadium-based hydrogen storage alloy containing Sm.

[0064] The performance of the Sm-containing vanadium-based hydrogen storage alloy prepared in this embodiment was tested, and the results are shown in Table 2 below.

[0065] Example 3 The general formula of the room-temperature activated vanadium-based hydrogen storage alloy in this embodiment is V 7.5 Ti 0.9 Cr 1.3 Fe 0.3 +0.008wt%Sm, as shown in Table 1 below, its preparation process includes the following steps: Step 1: Calculate and weigh each raw material according to the general formula and additional addition amount of vanadium-based hydrogen storage alloy for batching; considering the heat loss and volatilization of Sm during the smelting process, add an additional 200% by weight of Sm element to ensure the Sm content in the final alloy.

[0066] In the general formula of vanadium-based hydrogen storage alloys, the purity of raw materials V, Ti, Cr, Fe, and Sm all reach over 99%.

[0067] Step 2: Perform a single smelting process to prepare a master alloy that does not contain Sm elements; The raw materials V, Ti, Cr, and Fe are weighed according to the general formula ratio, and then placed in a water-cooled copper crucible. The crucible is then evacuated and filled with inert argon gas in an arc induction melting furnace for melting. After melting, the ingot is cooled, turned over, and melted again to obtain a master alloy free of Sm. The specific steps include the following: Step 21: Place the prepared V, Ti, Cr, and Fe raw materials into a water-cooled copper crucible, then place the water-cooled copper crucible in an electric arc induction melting furnace, and evacuate the furnace to 7×10⁻⁶. -2 Pa, then fill with inert protective gas argon until the vacuum pressure gauge shows -0.05MPa, and repeat the vacuuming and argon filling operation three times to completely remove the air from the furnace.

[0068] Step 22: Adjust the distance between the arc gun and the upper end of the sample to 5 mm before starting the arc. Step 23: After successful arc ignition, gradually increase the current to 180 A and raise the arc gun to a distance of 21 mm from the top of the sample. Each melting lasts for 4 minutes. After a single melting is completed, wait for the alloy ingot to cool, flip it 180°, and melt it again to obtain a master alloy without Sm elements.

[0069] Step 3: Perform secondary smelting to prepare vanadium-based hydrogen storage alloy containing Sm element; Step 31: Cool the Sm-free master alloy to 60°C or below. After opening the furnace, add the prepared Sm raw material to the Sm-free master alloy, and evacuate the furnace to 7×10⁻⁶ ℃. -2 Pa, fill with inert protective gas argon until the vacuum pressure gauge reaches -0.05 MPa, repeat the vacuuming and argon filling process three times to purge the air from the furnace, and fill with argon until the vacuum pressure gauge reaches -0.05 MPa; Step 32: Adjust the distance between the arc gun and the upper end of the sample to 5 mm before starting the arc. Step 33: After successful arc ignition, gradually increase the current to 180 A and slowly raise the arc gun so that the distance between the arc gun and the upper end of the sample reaches 21 mm; each melting lasts for 4 minutes. After a single melting is completed, wait for the alloy ingot to cool, flip it 180°, and melt it again to finally obtain a vanadium-based hydrogen storage alloy containing Sm.

[0070] The performance of the Sm-containing vanadium-based hydrogen storage alloy prepared in this embodiment was tested, and the results are shown in Table 2 below.

[0071] Example 4 The room-temperature activated vanadium-based hydrogen storage alloy equipped in this embodiment has the general formula V8Ti. 0.75 Cr 1.05 Fe 0.2 +0.008wt%Sm, as shown in Table 1 below, its preparation process includes the following steps: Step 1: Calculate and weigh each raw material according to the general formula and additional addition amount of vanadium-based hydrogen storage alloy for batching; considering the heat loss and volatilization of Sm during the smelting process, add an additional 200% by weight of Sm element to ensure the Sm content in the final alloy.

[0072] In the general formula of vanadium-based hydrogen storage alloys, the purity of raw materials V, Ti, Cr, Fe, and Sm all reach over 99%.

[0073] Step 2: Perform a single smelting process to prepare a master alloy that does not contain Sm elements; The raw materials V, Ti, Cr, and Fe are weighed according to the general formula ratio, and then placed in a water-cooled copper crucible. The crucible is then evacuated and filled with inert argon gas in an arc induction melting furnace for melting. After melting, the ingot is cooled, turned over, and melted again to obtain a master alloy free of Sm. The specific steps include the following: Step 21: Place the prepared V, Ti, Cr, and Fe raw materials into a water-cooled copper crucible, then place the water-cooled copper crucible in an electric arc induction melting furnace, and evacuate the furnace to a vacuum of 9×10⁻⁶. -2Pa, then fill with inert protective gas argon until the vacuum pressure gauge shows -0.06 MPa, and repeat the vacuuming and argon filling operation three times to completely remove the air from the furnace.

[0074] Step 22: Adjust the distance between the arc gun and the upper end of the sample to 5 mm before starting the arc. Step 23: After successful arc ignition, gradually increase the current to 180 A and raise the arc gun to a distance of 20 mm from the top of the sample. Each melting lasts for 4 minutes. After a single melting is completed, wait for the alloy ingot to cool, flip it 180°, and melt it again to obtain a master alloy without Sm elements.

[0075] Step 3: Perform secondary smelting to prepare vanadium-based hydrogen storage alloy containing Sm element; Step 31: Cool the Sm-free master alloy to 60°C or below. After opening the furnace, add the prepared Sm raw material to the Sm-free master alloy, and evacuate the furnace to 9×10⁻⁶ ℃. -2 Pa, fill with inert protective gas argon until the vacuum pressure gauge reaches -0.06 MPa, repeat the vacuuming and argon filling process three times to purge the air from the furnace, and fill with argon until the vacuum pressure gauge reaches -0.06 MPa; Step 32: Adjust the distance between the arc gun and the upper end of the sample to 5 mm before starting the arc. Step 33: After successful arc ignition, gradually increase the current to 180 A and slowly raise the arc gun so that the distance between the arc gun and the upper end of the sample reaches 20 mm; each melting lasts for 4 minutes. After a single melting is completed, wait for the alloy ingot to cool, flip it 180°, and melt it again to finally obtain a vanadium-based hydrogen storage alloy containing Sm.

[0076] The performance of the Sm-containing vanadium-based hydrogen storage alloy prepared in this embodiment was tested, and the results are shown in Table 2 below.

[0077] Comparative Example 1 The alloy in Comparative Example 1 has a composition of V7Ti. 1.1 Cr 1.6 Fe 0.3 Compared with Example 1, the only difference is that the hydrogen storage alloy of Comparative Example 1 did not contain the element Sm.

[0078] The performance of the Sm-free vanadium-based hydrogen storage alloy prepared in this comparative example was tested, and the results are shown in Table 2 below.

[0079] Comparative Example 2 The alloy in Comparative Example 2 has a composition of V8Ti. 0.75 Cr 1.05 Fe 0.2Compared with Example 4, the only difference is that the hydrogen storage alloy of Comparative Example 2 did not contain the element Sm.

[0080] The performance of the Sm-free vanadium-based hydrogen storage alloy prepared in this comparative example was tested, and the results are shown in Table 2 below.

[0081] Table 1 General Formulas for Examples and Comparative Examples

[0082] Table 2 Performance data of the examples and comparative alloys

[0083] It should be noted that the addition of Sm element to the hydrogen storage alloy of the present invention will reduce the maximum hydrogen storage capacity of the hydrogen storage alloy due to the formation of oxides by Sm element, which is a normal phenomenon. The main function of Sm element is to reduce the activation temperature and activation times. In the comparative example, the activation temperature and activation times of the alloy without Sm are significantly higher.

[0084] Analysis by comparing Table 1 and Table 2 shows that: (1) The alloy in Example 1 has a composition of V7Ti. 1.1 Cr 1.6 Fe 0.3 +0.005wt%Sm, meaning a trace amount of Sm was added to the basic vanadium-based alloy. The alloy in Comparative Example 1 has a composition of V7Ti. 1.1 Cr 1.6 Fe 0.3 It has the same basic alloy composition as in Example 1, but without the addition of Sm element.

[0085] According to the performance data in Table 2, the alloy with added Sm element in Example 1 requires only one activation at 40°C to be fully activated. Under hydrogen conditions of 40°C and 8 MPa, the time required to reach 90% of the maximum hydrogen storage capacity is 265 seconds (e.g., ...). Figure 2 As shown), the maximum hydrogen storage capacity is 3.59 wt%. After 100 cycles, the capacity retention rate is as high as 97.7%. In contrast, the alloy without added Sm in Comparative Example 1 requires an activation temperature as high as 400℃ and two activations to achieve complete activation. Under hydrogen conditions of 40℃ and 8MPa, the time required to reach 90% of the maximum hydrogen storage capacity is 650 seconds (as shown). Figure 2 As shown in the figure, the maximum hydrogen storage capacity is 3.55 wt%. After 100 cycles, the capacity retention rate is 97.0%.

[0086] Comparing Example 1 and Comparative Example 1, it can be seen that, with similar basic alloy compositions, the activation performance of the alloy was significantly improved simply by adding a trace amount of Sm (0.005 atomic ratio, Sm is a percentage). The activation temperature in Example 1 was drastically reduced from 400℃ in Comparative Example 1 to 40℃, the number of activations was reduced from 2 to 1, and the time required to reach 90% of the maximum hydrogen storage capacity was shortened from 650 seconds to 265 seconds, indicating a significantly faster hydrogen absorption rate. This fully demonstrates the crucial role of trace Sm in reducing the activation temperature and shortening the activation time of vanadium-based hydrogen storage alloys, enabling the alloy to achieve rapid activation and hydrogen absorption near room temperature, greatly improving its practicality.

[0087] Example 2: Alloy composition is V 7.2 Ti 1.0 Cr 1.6 Fe 0.2 +0.006wt%Sm. This composition fully conforms to the optimization range of this invention (x=7.2, y=1.0, z=1.6, a=0.2, b=0.006, where b is a mass percentage). According to the performance data in Table 2, this alloy requires only one activation at 40°C, reaches 90% of its maximum hydrogen storage capacity in 222 seconds, has a maximum hydrogen storage capacity of 3.61wt%, and retains 97.0% of its capacity after 100 cycles, demonstrating excellent overall performance.

[0088] The alloy composition of Example 3 is V 7.5 Ti 0.9 Cr 1.3 Fe 0.3 +0.008wt%Sm. According to the performance data in Table 2, the alloy can be fully activated in one activation at 40℃, and the time required to reach 90% of the maximum hydrogen storage capacity is 251 seconds. The maximum hydrogen storage capacity is 3.57wt%, and the capacity retention rate is 98.2% after 100 cycles, demonstrating excellent comprehensive performance.

[0089] The alloy in Example 4 has a composition of V8Ti. 0.75 Cr 1.05 Fe 0.2 +0.008wt%Sm, meaning a trace amount of Sm (0.008% Sm) was added to the basic vanadium-based alloy. The alloy in Comparative Example 2 has a composition of V8Ti. 0.75 Cr 1.05 Fe 0.2 The basic alloy composition and preparation process are the same as those in Example 4, except that Sm element is not added.

[0090] According to the performance data in Table 2, the Sm-added alloy in Example 4 requires only one activation at 40°C for complete activation. Under 40°C and 8 MPa hydrogen conditions, it takes 288 seconds to reach 90% of its maximum hydrogen storage capacity, with a maximum hydrogen storage capacity of 3.55 wt%. After 100 cycles, the capacity retention rate is as high as 97.7%. In contrast, the Sm-free alloy in Comparative Example 2 requires an activation temperature as high as 400°C and two activations for complete activation. Under 40°C and 8 MPa hydrogen conditions, it takes 650 seconds to reach 90% of its maximum hydrogen storage capacity, with a maximum hydrogen storage capacity of 3.55 wt%. After 100 cycles, the capacity retention rate is 98.5%.

[0091] Comparing Example 4 and Comparative Example 2, it can be seen that increasing the V content decreases both the activation ability and hydrogen absorption rate of the alloy. However, by adding a suitable, trace amount of Sm, the activation performance of the alloy is significantly improved. In Example 4, the activation temperature was drastically reduced from 400℃ in Comparative Example 1 to 40℃, the number of activations was reduced from 3 to 1, and the time required to reach 90% of the maximum hydrogen storage capacity was shortened from 750 seconds to 288 seconds. The hydrogen absorption rate was significantly accelerated, and the maximum capacity of the hydrogen storage alloy was also increased. This fully demonstrates the crucial role of appropriate, trace amounts of Sm in reducing the activation temperature and shortening the activation time of vanadium-based hydrogen storage alloys, enabling the alloy to achieve rapid activation and hydrogen absorption near room temperature while maintaining an increased effective hydrogen storage capacity.

[0092] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A vanadium-based hydrogen storage alloy that can be activated at room temperature, characterized in that, The general formula of the vanadium-based hydrogen storage alloy is V x Ti y Cr z Fe a +bwt%Sm; and the general formula satisfies the following conditions: x+y+z+a=10, 7≤x≤8, 0.7≤y≤1.4, 1.0≤z≤1.6, 0.2≤a≤0.3, 0.005≤b≤0.010; where x, y, z, and a are atomic ratios, and b is the mass percentage of Sm in the vanadium-based hydrogen storage alloy.

2. The room-temperature-activated vanadium-based hydrogen storage alloy according to claim 1, characterized in that, The general formula of the vanadium-based hydrogen storage alloy is V x Ti y Cr z Fe a +bwt%Sm; and the general formula satisfies the following conditions: x+y+z+a=10, 7≤x≤7.5, 0.7≤y≤1.2, 1.0≤z≤1.6, 0.2≤a≤0.3, 0.008≤b≤0.

01.

3. A method for preparing a room-temperature-activated vanadium-based hydrogen storage alloy, characterized in that, The preparation method is used to prepare the room-temperature activated vanadium-based hydrogen storage alloy according to claim 1 or 2; the preparation method includes the following steps: Step 1: Calculate and weigh each raw material according to the general formula and additional addition amount of vanadium-based hydrogen storage alloy for batching. Step 2: Perform a single smelting process to prepare a master alloy that does not contain Sm elements; V, Ti, Cr, and Fe raw materials were weighed according to the general formula ratio and placed in a water-cooled copper crucible. The furnace was evacuated and filled with inert argon gas for melting. After melting, the alloy ingot was cooled and turned over, and then melted again to obtain a master alloy without Sm. Step 3: Perform secondary smelting to prepare a vanadium-based hydrogen storage alloy containing Sm; Step 3 includes the following sub-steps: Step 31: Cool the Sm-free master alloy to 60°C or below. After opening the furnace, add the prepared Sm raw material to the Sm-free master alloy. Evacuate the furnace and fill it with inert protective gas argon. Repeat the evacuation and argon filling process three times to exhaust the air in the furnace. Step 32: Perform the arc initiation operation; Step 33: After successful arc ignition, smelting is carried out to finally obtain a vanadium-based hydrogen storage alloy containing Sm.

4. The method for preparing the room-temperature activated vanadium-based hydrogen storage alloy according to claim 3, characterized in that, In step 1, the Sm element is added with an additional 200% weight.

5. The method for preparing the room-temperature activated vanadium-based hydrogen storage alloy according to claim 4, characterized in that, In step 1, the purity of the raw materials V, Ti, Cr, Fe, and Sm in the vanadium-based hydrogen storage alloy all reaches 99% or higher.

6. The method for preparing a room-temperature-activated vanadium-based hydrogen storage alloy according to any one of claims 3 to 5, characterized in that, Step 2 includes the following sub-steps: Step 21: Place the prepared V, Ti, Cr, and Fe raw materials into a water-cooled copper crucible, and then place the water-cooled copper crucible into an electric arc induction melting furnace; evacuate the electric arc induction melting furnace to 10°C. -1 ~10 -3 Pa, then fill with inert protective gas until the vacuum pressure gauge shows -0.04~-0.06 MPa.

7. The method for preparing the room-temperature activated vanadium-based hydrogen storage alloy according to claim 6, characterized in that, In step 21, the vacuuming and inert gas filling operations are repeated three times to completely remove the air from the furnace.

8. The method for preparing the room-temperature activated vanadium-based hydrogen storage alloy according to claim 7, characterized in that, Step 2 also includes: Step 22: Adjust the distance between the arc gun and the upper part of the sample to 3-5 mm before starting the arc.

9. The method for preparing a room-temperature-activated vanadium-based hydrogen storage alloy according to claim 8, characterized in that, Step 2 also includes: Step 23: After successful arc ignition, increase the current to 180 A and raise the arc gun to a distance of 15-25 mm from the top of the sample. Each melting process lasts 3-5 minutes.

10. The method for preparing the room-temperature activated vanadium-based hydrogen storage alloy according to claim 9, characterized in that, In step 23, after the single melting is completed, the alloy ingot is cooled, flipped 180°, and melted again to obtain a master alloy that does not contain Sm elements.

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