High capacity easily activated ti-fe hydrogen storage alloy and method of making

Abstract

The application discloses a high-capacity easy-activation TiFe hydrogen storage alloy and a preparation method thereof, and relates to the field of hydrogen storage alloys. The hydrogen storage alloy has a general formula of Ti a Fe 49‑b‑c Cr b Co1Nb c RE d wherein 50<=a<=55, 2<=b<=4, 1<=c<=5, 1<=d<=4, and RE is a rare earth element. In the hydrogen storage alloy, Nb can increase the lattice parameter of the TiFe main phase, improve the hydrogen storage capacity, combine with excess Ti to form a separate phase to preferentially absorb hydrogen, improve the room-temperature activation performance, the existence of the rare earth element is beneficial to improving the cycle stability and activation performance, Co is beneficial to improving the hydrogen absorption and desorption platform and platform flatness, Cr is beneficial to improving the activation performance of TiFe, the TiFe alloy can realize rapid hydrogen absorption at room temperature, reaches the maximum hydrogen storage capacity within 4 hours, reduces energy consumption, the total hydrogen storage capacity is greater than 2wt%, and the effective hydrogen desorption capacity is greater than 1.7wt%.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage alloys, and more particularly to a high-capacity, easily activated TiFe hydrogen storage alloy and its preparation method. Background Technology

[0002] Hydrogen energy is a clean energy form characterized by high energy density and complete decarbonization, making it an ideal alternative to fossil fuels. Efficient and safe hydrogen storage methods are a key challenge for the development of hydrogen energy. Among existing hydrogen storage methods, high-pressure gaseous hydrogen storage is currently the most common, but its main problems are large volume and poor safety. Converting gaseous hydrogen into liquid hydrogen for storage at low temperatures can achieve high volumetric energy density; however, maintaining the low temperature requires a large amount of energy, approximately 30% of the stored energy.

[0003] Storing hydrogen in the form of metal hydrides is a feasible approach, offering advantages such as high volumetric hydrogen storage density, good safety, and high energy efficiency. Currently, various systems have been developed, including AB5, AB, AB2, superlattice, V-based solid solutions, and magnesium-based systems. Among these, AB5-type hydrogen storage alloys have been applied, but their hydrogen storage capacity is relatively low (approximately 1.5 wt%); while V-based solid solutions have a higher hydrogen storage capacity (approximately 3.5 wt%), V is expensive; magnesium-based hydrogen storage alloys have a hydrogen release temperature above 250 °C, making direct application difficult; AB, AB2, and superlattice types have similar hydrogen storage capacities (approximately 1.9 wt%), with AB-type alloys exhibiting a significant cost advantage.

[0004] AB-type hydrogen storage alloys are mainly represented by TiFe alloys. TiFe alloys primarily consist of the CsCl phase, which forms two hydrides, TiFeH and TiFeH2, after hydrogen absorption. These correspond to two plateaus in the PCT curve, with a theoretical hydrogen storage capacity of 1.86 wt%. TiFe alloys have the advantages of abundant raw material sources and low cost, leading to a wide range of applications and broad prospects. Currently, poor activation performance is a key issue restricting the application of TiFe hydrogen storage alloys. The presence of an oxide layer on the surface of TiFe alloys hinders hydrogen entry, requiring long-term activation under harsh conditions (6.5 MPa hydrogen pressure, 673 K) to achieve hydrogen storage. Furthermore, the phase composition is crucial to the hydrogen storage performance of TiFe. The formation of the TiFe phase requires a Ti content within the range of 49.7-52.5 at%. Deviations will result in the formation of the difficult-to-absorb TiFe2 phase and other irreversibly hydrogen-absorbing phases, affecting the capacity. Summary of the Invention

[0005] This invention provides a high-capacity, easily activated TiFe hydrogen storage alloy and its preparation method, which improves the activation performance of the TiFe hydrogen storage alloy, enables rapid hydrogen absorption at room temperature, reduces activation conditions, increases the lattice parameters of the TiFe main phase, and improves the hydrogen storage capacity.

[0006] To address the aforementioned technical problems, one objective of this invention is to provide a high-capacity, easily activated TiFe hydrogen storage alloy, wherein the general formula of the hydrogen storage alloy is: Ti a Fe 49-b-c Cr b Co1Nb c RE d , where 50≤a≤55, 2≤b≤4, 1≤c≤5, 1≤d≤4, and RE represents rare earth elements.

[0007] By adopting the above scheme, the hydrogen storage alloy of this application has CsCl phase (TiFe) and Ti... 0.97 Nb 0.03 Phase (c=1), Ti 0.7 Nb 0.3 The alloy contains a CsCl phase (TiFe) with c>1 and rare earth phases. The main phase is CsCl (TiFe). Nb partially replaces Fe in the TiFe alloy. Nb exists in the TiFe alloy as a solid solution, increasing the lattice parameters of the TiFe main phase, thereby improving hydrogen storage capacity and reducing hysteresis. Furthermore, Nb can combine with excess Ti in the TiFe alloy to form a separate phase that preferentially absorbs hydrogen, improving the room-temperature activation performance of the TiFe hydrogen storage alloy and enabling direct hydrogen absorption at room temperature with a short activation time. The presence of rare earth elements improves cycle stability and activation performance. Co improves the hydrogen absorption / desorption plateau and its flatness, while Cr helps improve the activation performance of TiFe. This results in a total hydrogen storage capacity greater than 2 wt% and an effective hydrogen release capacity greater than 1.7 wt% at 40℃ and a hydrogen pressure of 9.5 MPa. The capacity retention rate after 200 cycles is greater than 95%, and the alloy can rapidly and directly absorb hydrogen at room temperature, reaching maximum hydrogen storage capacity within 4 hours.

[0008] As a preferred embodiment, the RE is at least one of La, Ce, Y, Sm, and Pr.

[0009] As a preferred embodiment, the hydrogen storage alloy has a Ti composition. 52 Fe 45 Cr2Co1Nb2La2, Ti 50 Fe 43 Cr4Co1Nb2Y2, Ti 55 Fe 46 Cr2Co1Nb1Pr3, Ti 52 Fe 42 Cr2Co1Nb5Ce1, Ti 53 Fe 45 Cr3Co1Nb1La1, Ti 50 Fe 45 Any one of Cr2Co1Nb2La4.

[0010] To address the aforementioned technical problems, one objective of this invention is to provide a method for preparing a high-capacity, easily activated TiFe hydrogen storage alloy, comprising the following steps: The raw materials are prepared according to the stoichiometric ratio of the hydrogen storage alloy components, and then the raw materials are melted using an electric arc melting method. Each melting time is 3-10 minutes, and the melting is repeated 5-10 times. The melting temperature does not exceed 3000℃. After cooling, the materials are crushed and sieved to obtain powdered hydrogen storage alloy.

[0011] This application involves multiple melting processes. During the melting process, defects such as grain boundaries and coarse grains may appear in the crystal structure of the alloy. Through multiple solidification and remelting, it helps to refine the grains and improve the density and uniformity of the crystal structure. In addition, the melting temperature is controlled not to exceed 3000℃, which can avoid the volatilization of Cr, Co and rare earth elements at this temperature environment, which would reduce the content of Cr, Co and rare earth elements in the alloy and affect the activation performance and hydrogen storage capacity.

[0012] As a preferred embodiment, the raw material for the hydrogen storage alloy is a metallic element with a purity of 99% or higher.

[0013] As a preferred option, the smelting current during the smelting process is 120-180A, and the inert gas pressure is 400-800Pa.

[0014] As a preferred embodiment, the inert gas is at least one of argon, nitrogen, and helium.

[0015] As a preferred embodiment, the hydrogen storage alloy has a mesh size of 200-400 mesh.

[0016] As a preferred option, a vibration mill prototype is used to crush the alloy ingot, and the vibration milling time is 10-20 s.

[0017] As a preferred option, the melting temperature is 2500-3000℃.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. In this application, Nb exists in the TiFe alloy in the form of a solid solution, which increases the lattice parameters of the TiFe main phase, thereby increasing the hydrogen storage capacity and reducing hysteresis. Furthermore, Nb can also combine with excess Ti in the TiFe alloy to form a separate phase, which preferentially absorbs hydrogen and is beneficial to improving the room temperature activation performance of the TiFe hydrogen storage alloy. The presence of rare earth elements is beneficial to improving cycle stability and activation performance. Co is beneficial to improving the hydrogen absorption and desorption plateau and plateau flatness. Cr helps to improve the activation performance of TiFe, enabling the TiFe alloy to directly absorb hydrogen at room temperature with a short activation time.

[0019] 2. The hydrogen storage alloy of this application has a CsCl phase (TiFe) and a Ti phase. 0.97 Nb0.03 Phase (c=1), Ti 0.7 Nb 0.3 The phase (c>1) and rare earth phase, with the main phase being CsCl phase (TiFe), have a total hydrogen storage capacity of greater than 2wt% and an effective hydrogen release capacity of greater than 1.7 wt% at 40℃ and hydrogen pressure of 9.5MPa. The capacity retention rate after 200 cycles is greater than 95%. It can rapidly and directly absorb hydrogen at room temperature and reach the maximum hydrogen storage capacity within 4 hours. Attached Figure Description

[0020] Figure 1 : XRD images of a high-capacity, easily activated TiFe hydrogen storage alloy in Examples 1 and 5 of this invention; Figure 2 PCT curves of TiFe hydrogen storage alloys under different pressures, temperatures, and compositions were prepared for Examples 1, 4, and Comparative Example 4 of this invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available, and the same raw materials are used in parallel experiments.

[0023] Example 1 A high-capacity, easily activated TiFe hydrogen storage alloy, the composition of which is: Ti 52 Fe 45 Cr2Co1Nb2La2, comprising Ti, Fe, Cr, Co, Nb, and La in a stoichiometric ratio of 52:45:2:1:2:2, is prepared by the following steps: According to Ti 52 Fe 45 The Cr2Co1Nb2La2 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0024] Example 2 A high-capacity, easily activated TiFe hydrogen storage alloy, the composition of which is: Ti 50 Fe 43 Cr4Co1Nb2Y2, comprising Ti, Fe, Cr, Co, Nb, and Y in a stoichiometric ratio of 50:43:4:1:2:2, is prepared by the following steps: According to Ti 50 Fe 43 The Cr4Co1Nb2Y2 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 160 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 6 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0025] Example 3 A high-capacity, easily activated TiFe hydrogen storage alloy, the composition of which is: Ti 55 Fe 46 Cr2Co1Nb1Pr3, comprising Ti, Fe, Cr, Co, Nb, and Pr in a stoichiometric ratio of 55:46:2:1:1:3, is prepared by the following steps: According to Ti 55 Fe 46 The Cr2Co1Nb1Pr3 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A and an argon pressure of 600 Pa. Each melting time was 3 min. The alloy ingot was flipped and the melting was repeated 5 times. After cooling, the alloy ingot was crushed by a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0026] Example 4 A high-capacity, easily activated TiFe hydrogen storage alloy, the composition of which is: Ti 52 Fe 42 Cr2Co1Nb5Ce1, comprising Ti, Fe, Cr, Co, Nb and Ce in a stoichiometric ratio of 52:42:2:1:5:1, is prepared by the following steps: According to Ti 52 Fe 42The Cr2Co1Nb5Ce1 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0027] Example 5 A high-capacity, easily activated TiFe hydrogen storage alloy, the composition of which is: Ti 53 Fe 45 Cr3Co1Nb1La1, comprising Ti, Fe, Cr, Co, Nb, and La in a stoichiometric ratio of 53:45:3:1:1:1, is prepared by the following steps: According to Ti 53 Fe 45 The Cr3Co1Nb1La1 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0028] Example 6 A high-capacity, easily activated TiFe hydrogen storage alloy, the composition of which is: Ti 50 Fe 45 Cr2Co1Nb2La4, comprising Ti, Fe, Cr, Co, Nb, and La in a stoichiometric ratio of 50:45:2:1:2:4, is prepared by the following steps: According to Ti 50 Fe 45 The Cr2Co1Nb2La4 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0029] Comparative Example 1 A TiFe hydrogen storage alloy, the composition of which is: Ti 52 Fe 48 Cr6Co1Nb2La2, comprising Ti, Fe, Cr, Co, Nb, and La in a stoichiometric ratio of 52:48:6:1:2:2, is prepared by the following steps: According to Ti 52 Fe 48 The Cr6Co1Nb2La2 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0030] Comparative Example 2 A TiFe hydrogen storage alloy, the composition of which is: Ti 55 Fe 40 Cr2Co1Nb7La2, comprising Ti, Fe, Cr, Co, Nb, and La in a stoichiometric ratio of 55:40:2:1:7:2, is prepared by the following steps: According to Ti 55 Fe 40 The Cr2Co1Nb7La2 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0031] Comparative Example 3 A TiFe hydrogen storage alloy, the composition of which is: Ti 52 Fe 43 Cr2Co3Nb2La2, comprising Ti, Fe, Cr, Co, Nb and La in a stoichiometric ratio of 52:43:2:3:2:2, is prepared by the following steps: According to Ti 52 Fe 43The Cr2Co3Nb2La2 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0032] Comparative Example 4 A TiFe hydrogen storage alloy, the composition of which is: Ti 55 Fe 48 La2, comprising Ti, Fe, and La in a stoichiometric ratio of 55:48:2, is prepared by the following steps: According to Ti 55 Fe 48 The La2 alloy was prepared according to the stoichiometric ratio, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0033] Comparative Example 5 A TiFe hydrogen storage alloy, the composition of which is: Ti 52 Fe 48 Cr2Co1Nb2, comprising Ti, Fe, Cr, Co, and Nb in a stoichiometric ratio of 52:48:2:1:2, is prepared by the following steps: According to Ti 52 Fe 48 The Cr2Co1Nb2 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0034] Comparative Example 6 A TiFe hydrogen storage alloy, the composition of which is: Ti 52 Fe 47Co1Nb2La2, comprising Ti, Fe, Co, Nb, and La in a stoichiometric ratio of 52:47:1:2:2, is prepared by the following steps: According to Ti 52 Fe 47 The Co1Nb2La2 alloy was prepared by stoichiometric proportioning, with all elemental metals having a purity greater than 99%. The total alloy mass was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0035] Comparative Example 7 A TiFe hydrogen storage alloy, the composition of which is: Ti 52 Fe 46 Cr₂Nb₂La₂, comprising Ti, Fe, Cr, Nb, and La in a stoichiometric ratio of 52:46:2:2:2, is prepared by the following steps: According to Ti 52 Fe 46 The Cr2Nb2La2 alloy was prepared according to the stoichiometric ratio, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0036] Comparative Example 8 A TiFe hydrogen storage alloy, the composition of which is: Ti 52 Fe 45 Cr2Co1Nb2La2, comprising Ti, Fe, Cr, Co, Nb, and La in a stoichiometric ratio of 52:45:2:1:2:2, is prepared by the following steps: According to Ti 52 Fe 45 The Cr2Co1Nb2La2 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 150 A, a temperature of 2500-3000 °C, and an argon pressure of 600 Pa. Each melting time was 1 min. The alloy ingot was flipped and the melting was repeated twice. After cooling, a blocky hydrogen storage alloy was obtained.

[0037] Comparative Example 9 A TiFe hydrogen storage alloy, the composition of which is: Ti 52 Fe 45 Cr2Co1Nb2La2, comprising Ti, Fe, Cr, Co, Nb, and La in a stoichiometric ratio of 52:45:2:1:2:2, is prepared by the following steps: According to Ti 52 Fe 45 The Cr2Co1Nb2La2 alloy was prepared by stoichiometric proportioning, with the purity of all elemental metals being greater than 99%. The total mass of the alloy was 10 g. The raw materials were then melted in a vacuum arc at a current of 220 A, a temperature exceeding 3000 °C, and an argon pressure of 600 Pa. Each melting session lasted 3 min. The alloy ingot was flipped and the melting process was repeated 5 times. After cooling, the alloy ingot was crushed using a vibratory mill for 20 s. After sieving, a 300-mesh powder hydrogen storage alloy was obtained.

[0038] Performance testing 1. XRD data: The hydrogen storage alloys prepared in the examples and comparative examples were tested using an X-ray powder diffractometer (D8 Advance) from Bruker AXS GmbH, Germany. The test conditions were Cu kα rays with an angle of 20-90°. The lattice parameters of the TiFe main phase were calculated from the XRD data. The test results are shown in Table 1 below.

[0039] 2. Hydrogen Storage Performance: The hydrogen storage performance of the alloys prepared in the examples and comparative examples was tested using the PCT equipment (MH-PCT) of China Research Institute of Nonferrous Metals Industry Co., Ltd. The time to reach the maximum hydrogen storage capacity upon initial hydrogen absorption at room temperature was defined as the time taken for the sample to directly absorb hydrogen at 7 MPa hydrogen pressure without any heat treatment until reaching the maximum hydrogen storage capacity. Reversible hydrogen absorption / desorption pressure-composition-isothermal characteristic curves (PCT) were tested at 40℃, with a hydrogen pressure range of 0.001 MPa-9.5 MPa. The maximum hydrogen storage capacity was the maximum hydrogen storage capacity obtained from the PCT image, and the effective hydrogen storage capacity was the hydrogen storage capacity corresponding to the desorption to 0.1 MPa. The test results are shown in Table 1 below. Figure 2 As shown.

[0040] 3. Cyclic capacity retention rate: The hydrogen storage alloys prepared in the examples and comparative examples were subjected to hydrogen absorption at 3 MPa and 25°C for 25 min, followed by dehydrogenation at 300°C for 15 min, which was recorded as one cycle. After 200 cycles, hydrogen was absorbed at 40°C and 9.5 MPa hydrogen pressure. The ratio of the hydrogen storage capacity after 200 cycles to the maximum hydrogen storage capacity is the capacity retention rate after 200 cycles. The test results are shown in Table 1 below.

[0041] Table 1 - Performance test results of hydrogen storage alloys prepared in the embodiments and comparative examples of this application As shown in Table 1, compared with Example 1, Comparative Example 1 improved the activation performance of the hydrogen storage alloy by increasing the proportion of the Laves phase (AB2 structure) due to the increased Cr content, but the hydrogen absorption and desorption platform was more tilted, resulting in a decrease in the maximum hydrogen storage capacity.

[0042] As shown in Table 1, compared with Example 1, Comparative Example 2 has an increased maximum hydrogen storage capacity due to the increased Nb content, which increases the lattice parameters of the TiFe main phase. However, the hydrogen absorption and desorption plateau decreases, resulting in an increase in residual hydrogen and a decrease in effective hydrogen storage capacity.

[0043] As shown in Table 1, compared with Example 1, Comparative Example 3 increased the flatness of the hydrogen absorption and desorption platform due to the increased Co content, but reduced the TiFe main phase lattice parameters, resulting in a decrease in maximum hydrogen storage capacity and effective hydrogen storage capacity, and a deterioration in activation performance, with a longer time to reach maximum hydrogen storage capacity on the first hydrogen absorption.

[0044] As shown in Table 1 and Figure 2 As shown, compared to Example 1, Comparative Example 4 lacks the addition of Cr, Co and Nb, resulting in a decrease in maximum hydrogen storage capacity and effective hydrogen storage capacity, an increase in hysteresis, a deterioration in activation performance, and a longer time to reach maximum hydrogen storage capacity upon initial hydrogen absorption.

[0045] As shown in Table 1, compared with Example 1, Comparative Example 5 lacks the addition of rare earth element La, which leads to a deterioration in the activation performance and cycling performance of the hydrogen storage alloy, a decrease in the capacity retention rate after 200 cycles, and a longer time to reach the maximum hydrogen storage capacity on the first hydrogen absorption.

[0046] As shown in Table 1, compared with Example 1, Comparative Example 6 lacked the addition of Cr, which resulted in poorer activation performance of the hydrogen storage alloy, a longer time to reach the maximum hydrogen storage capacity on the first hydrogen absorption, and a decrease in the lattice parameters of the TiFe main phase, thus reducing the maximum hydrogen storage capacity and the effective hydrogen storage capacity.

[0047] As shown in Table 1, compared with Example 1, Comparative Example 7 lacked the addition of Co, which resulted in a more tilted hydrogen absorption and desorption platform and a corresponding reduction in effective hydrogen storage capacity.

[0048] As shown in Table 1, compared to Example 1, the hydrogen storage alloy of Comparative Example 8 was not subjected to crushing treatment, making it difficult for the block test to directly absorb hydrogen. This resulted in a significantly longer time to reach the maximum hydrogen storage capacity on the first attempt, and fewer melting times and cycles, leading to uneven internal elemental composition and affecting the hydrogen storage capacity. As shown in Table 1, compared to Example 1, the hydrogen storage alloy of Comparative Example 9 had a melting current of 220A and a melting temperature far exceeding 3000℃. Under these temperature conditions, some Cr, Co, and La elements in the alloy would volatilize, resulting in a reduction in Cr, Co, and La content. This prolonged activation time and decreased cycle performance of the synthesized hydrogen storage alloy.

[0049] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for preparing a high-capacity, easily activated TiFe hydrogen storage alloy, characterized in that, The hydrogen storage alloy has the following general formula: Ti a Fe 49-b-c Cr b Co1Nb c RE d Wherein, 50≤a≤55, 2≤b≤4, 1≤c≤5, 1≤d≤4, and RE represents rare earth elements; the mesh size of the hydrogen storage alloy is 200-400 mesh. The preparation method of the hydrogen storage alloy includes the following steps: The raw materials are prepared according to the stoichiometric ratio of the hydrogen storage alloy components, and then the raw materials are melted using an electric arc melting method. Each melting time is 3-10 minutes, and the melting is repeated 5-10 times. The melting temperature does not exceed 3000 ℃. After cooling, the materials are crushed and sieved to obtain powdered hydrogen storage alloy.

2. The method for preparing a high-capacity, easily activated TiFe hydrogen storage alloy as described in claim 1, characterized in that, The RE is at least one of La, Ce, Y, Sm and Pr.

3. The method for preparing a high-capacity, easily activated TiFe hydrogen storage alloy as described in claim 1, characterized in that, The hydrogen storage alloy is composed of Ti. 52 Fe 45 Cr2Co1Nb2La2, Ti 50 Fe 43 Cr4Co1Nb2Y2, Ti 55 Fe 46 Cr2Co1Nb1Pr3, Ti 52 Fe 42 Cr2Co1Nb5Ce1, Ti 53 Fe 45 Cr3Co1Nb1La1, Ti 50 Fe 45 Any one of Cr2Co1Nb2La4.

4. The method for preparing a high-capacity, easily activated TiFe hydrogen storage alloy as described in claim 1, characterized in that, The raw material for the hydrogen storage alloy is a metallic element with a purity of over 99%.

5. The method for preparing a high-capacity, easily activated TiFe hydrogen storage alloy as described in claim 1, characterized in that, During the smelting process, the smelting current is 120-180 A and the inert gas pressure is 400-800 Pa.

6. The method for preparing a high-capacity, easily activated TiFe hydrogen storage alloy as described in claim 5, characterized in that, The inert gas is at least one of argon, nitrogen, and helium.

7. The method for preparing a high-capacity, easily activated TiFe hydrogen storage alloy as described in claim 1, characterized in that, The alloy ingot was crushed using a vibration mill for 10-20 seconds.

8. The method for preparing a high-capacity, easily activated TiFe hydrogen storage alloy as described in claim 1, characterized in that, The melting temperature is 2500-3000 ℃.

9. A high-capacity, easily activated TiFe hydrogen storage alloy prepared by any one of the preparation methods described in claims 1-8.

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