TiCrNbV high-entropy hydrogen storage alloy with BCC structure and preparation method of TiCrNbV high-entropy hydrogen storage alloy

Abstract

The invention discloses a TiCrNbV high-entropy hydrogen storage alloy with a BCC structure, the component general formula of the high-entropy hydrogen storage alloy is (TiCr) x (NbV) y, in the general formula, x / 2 is more than or equal to 5 and less than or equal to 40 at.%, y / 2 is more than or equal to 5 and less than or equal to 40 at.%, and x + y = 100 at.%, the atomic proportions of Ti and Cr are the same, and the atomic proportions of Nb and V are kept the same; the valence electron concentration of the TiCrNbV high-entropy hydrogen storage alloy is always 5; the lattice distortion delta of the TiCrNbV high-entropy hydrogen storage alloy is greater than or equal to 4% and less than or equal to 5.5%; the high-entropy hydrogen storage alloy is of a single-phase BCC structure before hydrogen absorption and can still recover to the single-phase BCC structure after hydrogen desorption. The preparation method comprises the following steps: firstly, carrying out electric arc melting to obtain a TiCrNbV high-entropy hydrogen storage alloy ingot; and then mechanical crushing and sieving are carried out to obtain alloy powder, and finally, the alloy powder is subjected to activating treatment. When the hydrogen absorption / desorption temperature ranges from 30 DEG C to 70 DEG C, the maximum hydrogen absorption amount reaches 1.9 H / M to 2.1 H / M, and the maximum hydrogen desorption amount reaches 1.4 H / M to 1.7 H / M; the pressure of a hydrogen absorption platform reaches 10-40 bar, and the pressure of a hydrogen desorption platform reaches 0.03-1 bar.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen storage alloys, and particularly relates to a TiCrNbV high-entropy hydrogen storage alloy with a BCC structure and a preparation method thereof. BACKGROUND

[0002] The body-centered cubic structure BCC hydrogen storage alloy has the characteristics of high hydrogen storage capacity, mild hydrogenation reaction conditions and good hydrogen absorption kinetics due to the hydrogen and metal atomic ratio H / M reaching 2. However, the traditional BCC hydrogen storage alloy represented by vanadium-based hydrogen storage alloy has the problems of low reversible hydrogen storage capacity, low hydrogen release platform pressure and high price of raw materials.

[0003] In order to improve the hydrogen storage performance of the BCC hydrogen storage alloy, Ti, Cr, Fe, Mn and other elements can be added for improvement. For example, existing document 1 (Huang Z, Li C, Chu Y, et al. Potential and challenges for V-based solid solution hydrogen storage alloys. Energy, 2025: 134574.) can significantly improve the hydrogen release rate at room temperature by adding Ti and Cr, that is, improve the hydrogen release performance of the BCC alloy. However, the technical solution has the problems that the alloy surface is easy to form an oxide film, hindering the penetration and diffusion of hydrogen atoms into the alloy interior, so that the alloy is difficult to activate; at the same time, due to the weak affinity of the added elements and hydrogen, the hydrogen storage capacity of the alloy is reduced; in addition, there is a problem of forming other hydrides with higher thermal stability after hydrogen absorption, that is, disproportionation reaction occurs, resulting in a sharp drop in the cycle performance of the alloy.

[0004] In order to solve the above technical problems, there are three common solutions at present, which are respectively introducing multiple main elements to form a high-entropy hydrogen storage alloy, adjusting the valence electron concentration to adjust the hydrogen storage performance and adding alloy elements to catalyze the hydrogen release process.

[0005] Among them, by introducing multiple main elements, that is, the number of main elements is greater than or equal to 3, a high-entropy hydrogen storage alloy can be obtained to improve the hydrogen storage performance of the BCC hydrogen storage alloy. The principle is that the components of the high-entropy alloy are composed of equal atomic ratio or near equal atomic ratio, so that the high-entropy effect existing in the high-entropy alloy can make the alloy tend to form a single-phase solid solution rather than an intermetallic compound. For example, existing document 2 (Ek G, Kandemirli M, Yildiz YS, et al. Hydrogen storage properties of Ti-V-Cr-Mn-Ni high-entropy alloys. International Journal of Hydrogen Energy, 2017, 42(24): 15454-15463.) introduces multiple main elements to form a high-entropy hydrogen storage alloy to improve the hydrogen storage performance of the BCC hydrogen storage alloy. M M, Pavan AF, et al. Inorganic Chemistry, 2020, 60(2): 1124-1132) selects five components V, Ti, Zr, Nb, and Hf to prepare single-phase BCC high-entropy hydrogen storage alloy. The high-entropy hydrogen storage alloy obtained by the technical scheme is converted into single-phase hydride after absorbing hydrogen, that is, no disproportionation reaction occurs, and the hydrogen storage capacity H / M reaches 1.82-2.0. However, the technical problem of this technical scheme is that the dehydrogenation temperature of the obtained high-entropy hydrogen storage alloy is as high as 265-540℃. The reason is that the components of this technical scheme have strong affinity with hydrogen, and the binding force between metal atoms and hydrogen is strong, so it is necessary to destroy the structure of the hydride at a high temperature to make the hydrogen atoms separate from the metal atoms.

[0006] In addition, the technical scheme for regulating the valence electron concentration is as follows: M M, Ek G, Karlsson D, et al. Acta Materialia, 2019, 175: 121-129), by regulating the valence electron concentration of the BCC high-entropy hydrogen storage alloy, the thermal stability of the hydride is adjusted, thereby reducing the dehydrogenation temperature. Specifically, when the valence electron concentration is equal to 5, the BCC high-entropy hydrogen storage alloy has the best comprehensive performance in terms of hydrogen storage capacity and dehydrogenation temperature. When the atomic ratio is equal, the TiVNbCr high-entropy hydrogen storage alloy has a hydrogen storage capacity H / M close to 2 and a dehydrogenation temperature lower than 70℃. However, according to the experimental results provided by the existing literature, the dehydrogenation amount of the TiVNbCr high-entropy hydrogen storage alloy is less than 66.6% of the hydrogenation amount when the dehydrogenation temperature is lower than 70℃, that is, the technical scheme has the problem of high dehydrogenation temperature requirement.

[0007] In addition, according to existing literature 4 (Cheng B, Kong L, Cai H, et al. Exploring microstructure variations and hydrogen storage characteristics in TiVNbCrNi high-entropy alloys with different Ni incorporation. International Journal of Hydrogen Energy, 2024, 72: 29-40), it is also possible to add Ni element with catalytic activity to make Ti 25 V 30 Nb 10 Cr 35 The activation incubation time of the high-entropy hydrogen storage alloy is shortened from 3185 to 22s, and the hydrogen absorption and desorption speed is accelerated. However, in order to achieve the above technical effect, the hydrogen storage capacity is reduced from 1.86H / M to 1.27H / M.

[0008] Therefore, the prior art cannot balance high hydrogen release amount and low hydrogen release temperature. In addition, the preparation technology of the existing BCC high-entropy hydrogen storage alloy needs high-temperature heat treatment for the high-entropy hydrogen storage alloy prepared by arc melting. For example, according to the existing document 5 (a high-capacity long-life BCC type high-entropy hydrogen storage alloy and a preparation method thereof: 202411620676.0.2025-02-11.), after the TiNbCrMo high-entropy hydrogen storage alloy ingot obtained by arc melting is crushed into powder, direct hydrogen absorption and release performance test is carried out, the hydrogen release amount is only 51.1% of the hydrogen absorption amount; through multi-stage high-temperature heat treatment, i.e. the ingot is heated from room temperature to 1000℃ at a heating rate of 10℃ / min, then heated to 1200℃ at a heating rate of 1℃ / min and kept for 9min; then heated to 1300℃ at a heating rate of 1℃ / min and kept for 9min; then continue to heat to 1400℃ at a heating rate of 1℃ / min and keep for 30min, and finally nitrogen gas quenching, the hydrogen release amount can reach 71.5% of the hydrogen absorption amount.

[0009] Similarly, the existing document 6 (Jiangxi Institute of Rare Earths, Chinese Academy of Sciences, Shenzhen Guoke Hydrogen Source Technology Co., Ltd. A high-entropy hydrogen storage alloy and a preparation method thereof: 202310501531.8.2024-10-25) discloses that the composition general formula of the high-entropy hydrogen storage alloy is Ti a Cr b V c Mn d Mo e Ce f ; wherein 0.3≤a≤0.5, 0.05≤b≤0.2, 0.2≤c≤0.3, 0.25≤d≤0.4, 0.05≤e≤0.1, 0.01≤f≤0.03. The high-entropy hydrogen storage alloy ingot of the scheme needs to be heat treated at 1350-1450℃ to improve the composition uniformity, thereby reducing the inclination of the hydrogen absorption and release platform and improving the hydrogen storage performance.

[0010] From the existing document 5 and the existing document 6, it can be known that the high-temperature heat treatment can improve the hydrogen storage performance of the BCC high-entropy hydrogen storage alloy. The reason is that the high-temperature heat treatment can eliminate the casting organization dendritic segregation, improve the composition uniformity, and obtain a flat hydrogen absorption and release platform. Therefore, the conventional preparation method adopted by the prior art contains high-temperature heat treatment as a necessary technical feature. However, according to the research of the inventors of the present application, high-temperature heat treatment leads to two new technical problems:

[0011] 1. causing oxidation of the BCC high-entropy hydrogen storage alloy;

[0012] 2. increasing the complexity of the production process, i.e. increasing the production cost. SUMMARY

[0013] The technical problem to be solved by the present application is to provide a BCC high-entropy hydrogen storage alloy based on lattice distortion regulation and a preparation method thereof.

[0014] The lattice distortion δ is calculated by the following formula:

[0015]

[0016] In the formula, n is the number of components, c i and c j are the atomic percentages of components i and j, r i and r j are the atomic radii of components i and j; in the present application, the atomic radii of Ti, Cr, Nb, and V are 0.1462 nm, 0.1249 nm, 0.1429 nm, and 0.1316 nm, respectively.

[0017] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0018] A TiCrNbV high-entropy hydrogen storage alloy with a BCC structure, wherein the composition of the high-entropy hydrogen storage alloy is represented by the general formula (TiCr) x (NbV) y In the general formula, 5≤x / 2≤40 at.%, 5≤y / 2≤40 at.%, and x+y=100 at.%, and the atomic proportions of Ti and Cr are the same, and the atomic proportions of Nb and V are the same.

[0019] The valence electron concentration of the TiCrNbV high-entropy hydrogen storage alloy is constant at 5, i.e., 10x+10y=5.

[0020] The lattice distortion of the TiCrNbV high-entropy hydrogen storage alloy is 4%≤δ≤5.5%.

[0021] The high-entropy hydrogen storage alloy is a single-phase BCC structure before absorbing hydrogen and can still recover to a single-phase BCC structure after releasing hydrogen.

[0022] A preparation method of a TiCrNbV high-entropy hydrogen storage alloy, comprising the following steps: firstly, arc melting metal elements of Ti, Cr, Nb and V in a certain molar ratio, and then pouring the molten alloy into a water-cooled copper mold to obtain a TiCrNbV high-entropy hydrogen storage alloy ingot; then, mechanically crushing and sieving the ingot to obtain alloy powder, and finally, activating the alloy powder to obtain a TiCrNbV high-entropy hydrogen storage alloy for hydrogen storage;

[0023] The arc melting condition is that high-purity argon is used as a protective gas, electromagnetic stirring is performed during melting, the melting current is 200-450 A, the melting time is 10-100 s / time, the melting times are 5, and the ingot is turned over after cooling after each melting; the sieving condition is that the particle size requirement is 50-300 mesh;

[0024] The activation condition is that a two-step activation method is used, the first step activation condition is that the activation temperature is 20-50 DEG C, the hydrogen pressure is 1-20 bar, and the activation time is 0.15-2 h;

[0025] The second step activation condition is that the activation temperature is 300-600 DEG C, the hydrogen pressure is 0.0005-0.005 bar, and the activation time is 0.5-4 h.

[0026] The obtained TiCrNbV high-entropy hydrogen storage alloy has a maximum hydrogen absorption capacity of 1.9-2.1H / M and a maximum hydrogen release capacity of 1.4-1.7H / M in the hydrogen absorption / release temperature range of 30-70 DEG C; the hydrogen absorption plateau pressure is 10-40 bar, and the hydrogen release plateau pressure is 0.03-1 bar.

[0027] The technical effects of the application are detected by experiments as follows:

[0028] It can be known from EDS testing that the actual composition of the TiCrNbV high-entropy hydrogen storage alloy has no substantial difference from the nominal composition, meets the composition characteristics of high-entropy alloys, and the element distribution is uniform;

[0029] It can be known from XRD testing that the TiCrNbV high-entropy hydrogen storage alloy has only a single-phase BCC structure with a lattice distortion delta of 5.1%-6.3; reducing the lattice distortion delta can inhibit the disproportionation reaction and is beneficial to maintaining the single-phase structure of the alloy;

[0030] It can be known from SEM testing that the TiCrNbV high-entropy hydrogen storage alloy has a single-phase structure;

[0031] The hydrogen absorption / desorption performance test shows that, in the hydrogen absorption / desorbion temperature range of 30-70 DEG C, with the lattice distortion delta decreasing from 6.3% to 5.1%, the hydrogen absorption amount of the TiCrNbV high-entropy hydrogen storage alloy is kept at 2.0H / M, the hydrogen desorption amount increases, and the hydrogen absorption / desorption plateau pressure increases. Among them, under the condition of hydrogen absorption / desorption temperature of 30 DEG C, the maximum hydrogen desorption amount is 1.58H / M.

[0032] Compared with the prior art, the present application has the following advantages:

[0033] 1. The present application designs alloy composition by regulating lattice distortion, and the obtained (TiCr) 20 (NbV) 80 high-entropy hydrogen storage alloy has a hydrogen absorption amount H / M of 2.00-2.08, a hydrogen desorption amount H / M of 1.55-1.58, and a hydrogen desorption rate of 75.7-77.4% at a working temperature of 30 DEG C-70 DEG C, and has excellent and stable hydrogen absorption / desorption performance, and can be applied in the field of vehicle-mounted hydrogen storage;

[0034] 2. The preparation method of the present application has simple steps, and the obtained ingot does not need high-temperature heat treatment, and the controllable preparation of the alloy is easy to realize;

[0035] 3. The present application can reduce the solid solution strengthening effect of the high-entropy hydrogen storage alloy by reducing the lattice distortion, reduce the strength or hardness, make it easy to break subsequently, and reduce the preparation difficulty;

[0036] 4. The present application calculates the lattice distortion delta based on the empirical parameter method, and successfully designs a high-entropy hydrogen storage alloy with high hydrogen desorption amount at a working temperature of 30 DEG C-70 DEG C. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is the lattice distortion value (delta) of the high-entropy hydrogen storage alloy of example 1, comparative example 1, comparative example 3 and comparative example 4;

[0038] Figure 2 is the SEM image of TCNV-2 / 8 prepared in example 1;

[0039] Figure 3 is the XRD pattern of the high-entropy hydrogen storage alloy of example 1, comparative example 1, comparative example 2, comparative example 3 and comparative example 4 after activation;

[0040] Figure 4 is the PCT curve of TCNV-2 / 8 prepared in example 1;

[0041] Figure 5 is the XRD pattern of the high-entropy hydrogen storage alloy of example 1, comparative example 1, comparative example 3 and comparative example 4 after hydrogen desorption at 30 DEG C;

[0042] Figure 6SEM image of TCNV-5 / 5 prepared in Comparative Example 1;

[0043] Figure 7 PCT curve of TCNV-5 / 5 prepared in Comparative Example 1;

[0044] Figure 8 SEM image of TCNV-3 / 7 prepared in Comparative Example 3;

[0045] Figure 9 PCT curve of TCNV-3 / 7 prepared in Comparative Example 3;

[0046] Figure 10 SEM image of TCNV-4 / 6 prepared in Comparative Example 4;

[0047] Figure 11 PCT curve of TCNV-4 / 6 prepared in Comparative Example 4;

[0048] Figure 12 Comparison of hydrogen release amount of high-entropy hydrogen storage alloy in Example 1, Comparative Example 1, Comparative Example 3 and Comparative Example 4 at 30℃. DETAILED DESCRIPTION

[0049] The present application will be further described in the context of the following examples, in conjunction with the accompanying drawings. These examples are for comparative and explanatory purposes only and the present application is not limited to these examples.

[0050] In order to distinguish various alloys and their basic information involved in each example and comparative example, the following is first described. Specifically, in the examples and comparative examples, the chemical general formula of the TiCrNbV high-entropy hydrogen storage alloy satisfies (TiCr) x (NbV) y wherein x+y=100, x=20, 30, 40, 50, and the valence electron concentration of the TiCrNbV high-entropy hydrogen storage alloy is constant at 5.

[0051] The principle of the chemical general formula is to keep the atomic ratio of Ti and Cr the same, which is referred to as (Ti+Cr), and at the same time, keep the atomic ratio of Nb and V the same, which is referred to as (Nb+V), and then change the ratio of (Ti+Cr) and (Nb+V) to adjust the lattice distortion δ of the TiCrNbV high-entropy hydrogen storage alloy. The calculated results of the lattice distortion δ of the TiCrNbV high-entropy hydrogen storage alloy are shown in Table 1. Figure 1 and Table 1.

[0052] Table 1 Chemical general formula and lattice distortion of TiCrNbV high-entropy hydrogen storage alloy

[0053] Chemical formula Abbreviation Lattice distortion δ Example 1 (TiCr) 20 (NbV) 80 ]]> TCNV-2 / 8 5.1 Comparative Example 3 (TiCr) 30 (NbV) 70 ]]> TCNV-3 / 7 5.5 Comparative Example 4 (TiCr) 40 (NbV) 60 ]]> TCNV-4 / 6 5.9 Comparative Example 1 (TiCr) 50 (NbV) 50 ]]> TCNV-5 / 5 6.3

[0054] Embodiment 1

[0055] A preparation method of a TiCrNbV high-entropy hydrogen storage alloy with a lattice distortion δ = 5.1%, comprising the following steps: first, arc melting Ti, Cr, Nb and V in a certain amount-of-substance ratio, and then pouring the molten alloy into a water-cooled copper mold to obtain a TiCrNbV high-entropy hydrogen storage alloy ingot; then, mechanically crushing and sieving the alloy ingot to obtain alloy powder, and finally, activating the alloy powder to obtain the TiCrNbV high-entropy hydrogen storage alloy, and according to the composition characteristics, the TiCrNbV high-entropy hydrogen storage alloy obtained in Embodiment 1 is (TiCr) 20 (NbV) 80 high-entropy hydrogen storage alloy, therefore, it is referred to as TCNV-2 / 8.

[0056] The amount-of-substance ratio of Ti, Cr, Nb and V is 10:10:40:40, that is, the amount-of-substance ratio of (Ti+Cr) to (Nb+V) is 20:80;

[0057] The arc melting conditions are as follows: high-purity argon is used as the protective gas, electromagnetic stirring is performed during melting, the melting current is 350 A, the melting time is 60 s / time, the melting times is 5, and the alloy is turned over after cooling after each melting;

[0058] The sieving conditions are as follows: the particle size requirement is 100 mesh;

[0059] The activation conditions of TCNV-2 / 8 are as follows: first, first-step activation is performed at an activation temperature of 30℃, an activation hydrogen pressure of 10 bar and an activation time of 0.5 h, and then, second-step activation is performed at an activation temperature of 400℃, an activation hydrogen pressure of 0.0005 bar and an activation time of 2 h.

[0060] In order to prove the composition content of TCNV-2 / 8, that is, to prove that the actual composition is consistent with the nominal composition, EDS test is performed. The test results are shown in Figure 2 and Table 2, the atomic percentages of Ti, Cr, Nb and V are 10.3at.%, 9.7at.%, 38.0at.% and 42.0at.% respectively, which has no substantial difference with the nominal composition. The test results show that TCNV-2 / 8 meets the composition characteristics of high-entropy alloy.

[0061] Table 2 Actual composition of TiCrNbV high-entropy hydrogen storage alloy

[0062] Ti (at. %) Cr (at. %) Nb (at. %) V (at. %) Example 1 10.3 9.7 38.0 42.0 Comparative Example 3 15.2 15.0 32.9 36.9 Comparative Example 4 20.3 20.0 28.2 31.4 Comparative Example 1 25.3 25.1 23.2 26.4

[0063] In order to prove the crystal structure of TCNV-2 / 8, XRD analysis is performed. The test results are shown inFigure 3 As shown in FIG. 2, TCNV-2 / 8 only has one characteristic peak of BCC structure, and the lattice constant is a = 3.27 A. The test results show that TCNV-2 / 8 is a single-phase BCC structure.

[0064] In order to further prove that TCNV-2 / 8 is a single-phase structure, SEM test is carried out. The test results are shown in FIG. 3. Figure 2 As shown in FIG. 3, TCNV-2 / 8 does not have a second phase, that is, it is a single-phase structure. In combination with the EDS test results, it can be known that TCNV-2 / 8 has no obvious element segregation.

[0065] In order to prove the hydrogen storage performance of TCNV-2 / 8, hydrogen absorption / desorption thermodynamic PCT test is carried out, and the mass hydrogen storage capacity is converted into the atomic ratio of hydrogen to metal H / M. The test results are shown in Table 2 and FIG. 4. Figure 4 and Table 3,

[0066] Under the condition that the hydrogen absorption / desorption temperature is 30°C, the hydrogen absorption amount is 2.08H / M, the hydrogen desorption amount is 1.58H / M, the hydrogen absorption plateau pressure is 10.98bar, and the hydrogen desorption plateau pressure is 0.07bar;

[0067] Under the condition that the hydrogen absorption / desorption temperature is 50°C, the hydrogen absorption amount is 2.0H / M, the hydrogen desorption amount is 1.55H / M, the hydrogen absorption plateau pressure is 12.56bar, and the hydrogen desorption plateau pressure is 0.24bar;

[0068] Under the condition that the hydrogen absorption / desorption temperature is 70°C, the hydrogen absorption amount is 2.04H / M, the hydrogen desorption amount is 1.58H / M, the hydrogen absorption plateau pressure is 30.53bar, and the hydrogen desorption plateau pressure is 0.64bar.

[0069] The test results show that within the range of 30-70°C of the hydrogen absorption / desorption temperature, the temperature has no significant effect on the hydrogen absorption amount and the hydrogen desorption amount, but increasing the temperature can increase the hydrogen absorption plateau pressure and the hydrogen desorption plateau pressure.

[0070] Note: The TiCrNbV high-entropy hydrogen storage alloy after hydrogen absorption / desorption is referred to as TCNV-D, and the TCNV-D obtained in specific embodiment 1 is referred to as TCNV-2 / 8-D.

[0071] In order to prove the influence of hydrogen absorption / desorption on the crystal structure, XRD test is carried out on TCNV-2 / 8-D. The test results are shown in FIG. 5. Figure 5 As shown in FIG. 5, TCNV-2 / 8-D only has one characteristic peak of BCC structure. The test results show that TCNV-2 / 8-D is a single-phase BCC structure. In comparison with the XRD test results of TCNV-2 / 8, it can be known that TCNV-2 / 8 can restore the single-phase BCC structure after hydrogen absorption / desorption, that is, the hydrogen absorption / desorption process does not affect the crystal structure of TCNV-2 / 8.

[0072] Table 3 Hydrogen absorption / desorption properties and crystal structure of TiCrNbV high-entropy hydrogen storage alloy at 30℃

[0073]

[0074] To further prove the influence of lattice distortion on the hydrogen storage performance of TiCrNbV high-entropy hydrogen storage alloy, reference literature is provided for comparison, as shown in Table 4.

[0075] Table 4 Comparison of hydrogen desorption amount of TCNV-2 / 8 at 30℃ and other alloys at room temperature

[0076]

[0077] 1. Cheng B, Kong L, Cai H, et al. Exploring microstructure variations and hydrogen storage characteristics in TiVNbCrNi high-entropy alloys with different Ni incorporation. International Journal of Hydrogen Energy. 2024; 60: 282-292.

[0078] 2. Cheng B, Kong L, Cai H, et al. Pushing the Boundaries of solid-state hydrogen storage: A Refined study on TiVNbCrMo high-entropy alloys. International Journal of Hydrogen Energy. 2024; 60: 282-292.

[0079] 3. Wu Z, Yang C, Yan Y, et al. Effect of dehydrogenation depth on cyclic hydrogen desorption properties of V40Ti25.5Cr26.5Fe8 alloy. Journal of Alloys and Compounds, 2023, 955: 170036.

[0080] 4、Zhang X, Liu Y, Hu H, et al. Development of high-performance and low-cost BCC type hydrogen storage alloys from FeV80 master alloy refined by cerium. Journal of Rare Earths, 2025.

[0081] According to the prior reference 1, in the high-entropy hydrogen storage alloy TiVNbCrNi system, the content of Ni element, that is, the Cr / Ni ratio has negligible effect on lattice distortion, but the hydrogen release amount changes significantly. That is, the person skilled in the art can obtain the conclusion that "the increase of hydrogen release amount is irrelevant to lattice distortion" from the prior literature 1-1;

[0082] According to the prior reference 2, in the high-entropy hydrogen storage alloy TiCrNbVMo system, the content of Mo element, that is, the Cr / Mo ratio can change the lattice distortion, but although the hydrogen release amount changes, the change of the hydrogen release amount is not regular. That is, the person skilled in the art cannot obtain the technical inspiration about "hydrogen release amount and lattice distortion" from the prior literature 1-2;

[0083] The person skilled in the art can preliminarily obtain the following conclusion from the comparison of reference 3 and reference 4: "increasing lattice distortion can increase the hydrogen release amount of BCC high-entropy hydrogen storage alloy"; but further combined with example 1 of the present application, it is known that the above conclusion is not true.

[0084] Therefore, according to the above analysis of the prior art, it is known that the prior art cannot determine the relationship between the hydrogen release amount and the lattice distortion of high-entropy hydrogen storage alloy, that is, it cannot give technical inspiration.

[0085] In order to prove the influence of the conventional high-entropy hydrogen storage alloy, that is, the amount-of-substance ratio of Ti, Cr, Nb and V is 1:1:1:1, on the hydrogen storage performance of TiCrNbV high-entropy hydrogen storage alloy, comparative example 1 is provided.

[0086] Comparative example 1

[0087] A preparation method of a TiCrNbV high-entropy hydrogen storage alloy with a lattice distortion δ of 6.3%, the steps not specifically described are the same as those of example 1, the difference is that the amount-of-substance ratio of Ti, Cr, Nb and V is 25:25:25:25, that is, the amount-of-substance ratio is 1:1:1:1, that is, the amount-of-substance ratio of (Ti+Cr) to (Nb+V) is 50:50, corresponding to a lattice distortion δ of 6.3%, therefore, the obtained TiCrNbV high-entropy hydrogen storage alloy is (TiCr)50 (NbV) 50 High-entropy hydrogen storage alloy, referred to as TCNV-5 / 5, and TCNV-5 / 5 obtained after corresponding hydrogen absorption / desorption is referred to as TCNV-5 / 5-D.

[0088] The EDS test results of TCNV-5 / 5 are shown in Table 2, and the atomic percentages of Ti, Cr, Nb and V are 25.3at.%, 25.1at.%, 23.2at.% and 26.4at.% respectively, which has no substantial difference from the nominal composition. The test results show that TCNV-5 / 5 meets the composition characteristics of high-entropy alloy.

[0089] The XRD test results of TCNV-5 / 5 are shown in Figure 3 The XRD test results of TCNV-5 / 5 are shown in The test results show that TCNV-5 / 5 is a single-phase BCC structure.

[0090] The SEM test results of TCNV-5 / 5 are shown in Figure 6 The SEM test results of TCNV-5 / 5 are shown in The SEM test results of TCNV-5 / 5 are shown in

[0091] The PCT test results of TCNV-5 / 5 are shown in Figure 7 and Table 3,

[0092] Under the condition that the hydrogen absorption / desorption temperature is 30℃, the hydrogen absorption amount is 2.02H / M, the hydrogen desorption amount is 0.57H / M, the hydrogen absorption plateau pressure is 1.52bar, and the hydrogen desorption plateau pressure is 0.01bar;

[0093] Under the condition that the hydrogen absorption / desorption temperature is 50℃, the hydrogen absorption amount is 2.03H / M, the hydrogen desorption amount is 1.45H / M, the hydrogen absorption plateau pressure is 1.83bar, and the hydrogen desorption plateau pressure is 0.04bar;

[0094] Under the condition that the hydrogen absorption / desorption temperature is 70℃, the hydrogen absorption amount is 2.0H / M, the hydrogen desorption amount is 1.56H / M, the hydrogen absorption plateau pressure is 3.52bar, and the hydrogen desorption plateau pressure is 0.12bar.

[0095] The test results show that within the range of 30-70℃ of hydrogen absorption / desorption temperature, the temperature has no significant effect on the hydrogen absorption amount, but increasing the temperature can increase the hydrogen desorption amount, and can also increase the hydrogen absorption plateau pressure and the hydrogen desorption plateau pressure.

[0096] The XRD test results of TCNV-5 / 5-D are shown in Figure 5As shown, TCNV-5 / 5-D exhibits peaks characteristic of FCC hydrides in addition to the characteristic peaks of the BCC structure. According to common knowledge in the art, the higher the thermal stability of a hydride, the more difficult it is to dehydrogenate. This is because the binding force between metal atoms and hydrogen is strong, requiring higher temperatures to break the hydride structure. Therefore, XRD test results indicate that TCNV-5 / 5 forms a thermodynamically stable hydride after hydrogen absorption, resulting in some FCC hydrides failing to revert to a BCC alloy during subsequent dehydrogenation.

[0097] By comparing Comparative Example 1 with Example 1, it can be seen that when the molar ratio of (Ti+Cr) to (Nb+V) is 50:50, although a TiCrNbV high entropy hydrogen storage alloy can also be obtained, compared with TCNV-2 / 8, TCNV-5 / 5 has some FCC hydrides after hydrogen absorption and desorption that cannot be restored to BCC alloy, so the hydrogen desorption amount is lower.

[0098] In order to demonstrate the effect of conventional high entropy hydrogen storage alloy processing methods, namely heat treatment, on the hydrogen storage properties of TiCrNbV high entropy hydrogen storage alloys, comparative example 2 is provided, in which the TCNV-5 / 5 of comparative example 1 is heat treated before mechanical crushing to obtain a TiCrNbV high entropy hydrogen storage alloy.

[0099] Comparative Example 2

[0100] A method for preparing a heat-treated TiCrNbV high-entropy hydrogen storage alloy, wherein the steps not otherwise specified are the same as those in Comparative Example 1, except that the TCNV-5 / 5 ingot is heat-treated before mechanical crushing, and the obtained TiCrNbV high-entropy hydrogen storage alloy is referred to as TCNV-5 / 5-A.

[0101] The heat treatment conditions are as follows: a heat treatment temperature of 1200° C., a heat treatment time of 12 h, an argon pressure of 5 bar, and water quenching after the heat treatment.

[0102] The XRD test results of TCNV-5 / 5-A are as follows: Figure 3 As shown in the figure, after heat treatment, TCNV-5 / 5-A has characteristic peaks of NbCr2 phase in addition to BCC structure, which means it is not a single-phase BCC structure. The test results show that heat treatment will cause precipitation phase in the alloy.

[0103] The PCT test results of TCNV-5 / 5-A show that under the condition of hydrogen absorption / desorption temperature of 30℃, the hydrogen absorption amount is 0.1H / M and the hydrogen desorption amount is zero. In addition, the hydrogen absorption platform pressure is less than 0.05bar and the hydrogen desorption platform pressure is less than 0.05bar.

[0104] It can be seen from the comparison of Comparative Example 2 and Example 1 that the TiCrNbV high-entropy hydrogen storage alloy will form a NbCr2 phase after high-temperature heat treatment.

[0105] In order to further prove the influence of the molar ratio of Ti, Cr, Nb and V, i.e. the lattice distortion, on the hydrogen storage performance of the TiCrNbV high-entropy hydrogen storage alloy, Example 2 and Example 3 are provided, in which the lattice distortion of the TiCrNbV high-entropy hydrogen storage alloy is 5.5% and 5.9%, respectively.

[0106] Comparative Example 3

[0107] A method for preparing a TiCrNbV high-entropy hydrogen storage alloy with a lattice distortion δ of 5.5%, wherein the steps not specifically described are the same as those of Example 1, and the difference lies in that the molar ratio of Ti, Cr, Nb and V is 15:15:35:35, i.e. the molar ratio of (Ti+Cr) to (Nb+V) is 30:70, corresponding to a lattice distortion δ of 5.5%, and therefore the obtained TiCrNbV high-entropy hydrogen storage alloy is (TiCr) 30 (NbV) 70 The high-entropy hydrogen storage alloy is referred to as TCNV-3 / 7, and the TCNV-3 / 7 obtained after absorbing and desorbing hydrogen is referred to as TCNV-3 / 7-D.

[0108] The EDS test results of TCNV-3 / 7 are shown in Table 2, and the atomic percentages of Ti, Cr, Nb and V are 15.2at.%, 15.0at.%, 32.9at.% and 36.9at.%, respectively, which have no substantial difference from the nominal composition. The test results show that TCNV-3 / 7 meets the composition characteristics of high-entropy alloys.

[0109] The XRD test results of TCNV-3 / 7 are shown in Figure 3 The test results show that TCNV-3 / 7 is a single-phase BCC structure.

[0110] The SEM test results of TCNV-3 / 7 are shown in Figure 8 The test results show that TCNV-3 / 7 does not have a second phase, i.e. it is a single-phase structure. In combination with the EDS test results, it can be seen that TCNV-3 / 7 has no obvious element segregation.

[0111] The PCT test results of TCNV-3 / 7 are shown in Figure 9 and Table 3,

[0112] Under the condition that the hydrogen absorption / desorption temperature is 30℃, the hydrogen absorption amount is 2.08H / M, the hydrogen desorption amount is 1.06H / M, the hydrogen absorption plateau pressure is 3.81bar, and the hydrogen desorption plateau pressure is 0.03bar.​

[0113] At a hydrogen absorption / desorption temperature of 50°C, the hydrogen absorption capacity is 2.05H / M, the hydrogen desorption capacity is 1.54H / M, and the hydrogen absorption platform pressure is 6.49bar, and the hydrogen desorption platform pressure is 0.11bar.

[0114] When the hydrogen absorption / desorption temperature is 70°C, the hydrogen absorption amount is 1.99H / M, the hydrogen desorption amount is 1.54H / M, and the hydrogen absorption platform pressure is 17.0bar, and the hydrogen desorption platform pressure is 0.31bar.

[0115] The test results show that when the hydrogen absorption / desorption temperature is in the range of 30-70℃, the temperature has no significant effect on the hydrogen absorption amount, but increasing the temperature can increase the hydrogen desorption amount, and can also increase the hydrogen absorption platform pressure and the hydrogen desorption platform pressure.

[0116] The XRD test results of TCNV-3 / 7-D are as follows: Figure 5 As shown, TCNV-3 / 7-D exhibits only one characteristic peak of the BCC structure. The test results indicate that TCNV-3 / 7-D has a single-phase BCC structure. Comparison with the XRD results of TCNV-3 / 7 reveals that TCNV-3 / 7 can recover a single-phase BCC structure after hydrogen absorption and desorption.

[0117] By comparing Comparative Example 3 with Example 1, it can be seen that when the molar ratio of (Ti+Cr) to (Nb+V) is 30:70, TiCrNbV high entropy hydrogen storage alloy can be obtained.

[0118] Comparative Example 4

[0119] A method for preparing a TiCrNbV high entropy hydrogen storage alloy with a lattice distortion δ=5.9%, wherein the steps not specifically described are the same as those in Example 1, except that the molar ratio of Ti, Cr, Nb, and V is 20:20:30:30, that is, the molar ratio of (Ti+Cr) to (Nb+V) is 40:60, corresponding to a lattice distortion δ=5.5%. Therefore, the obtained TiCrNbV high entropy hydrogen storage alloy is (TiCr) 40 (NbV) 60 The high entropy hydrogen storage alloy is abbreviated as TCNV-4 / 6, and the TCNV-4 / 6 obtained after the corresponding absorption / desorption of hydrogen is abbreviated as TCNV-4 / 6-D.

[0120] Table 2 shows the EDS results for TCNV-4 / 6. The atomic percentages of Ti, Cr, Nb, and V are 20.3 at.%, 20.0 at.%, 28.2 at.%, and 31.4 at.%, respectively, showing no substantial differences from the nominal composition. These results demonstrate that TCNV-4 / 6 meets the compositional characteristics of a high-entropy alloy.

[0121] The XRD test result of the TCNV-4 / 6 is shown in Figure 3 As shown in the figure, the TCNV-4 / 6 only has one characteristic peak of BCC structure, and the lattice constant is The test result shows that the TCNV-4 / 6 is a single-phase BCC structure.

[0122] The SEM test result of the TCNV-4 / 6 is shown in Figure 10 As shown in the figure, the TCNV-4 / 6 does not have a second phase, i.e. a single-phase structure. In combination with the EDS test result, it can be known that the TCNV-4 / 6 has no obvious element segregation.

[0123] The PCT test result of the TCNV-4 / 6 is shown in Figure 11 and Table 3,

[0124] Under the condition that the hydrogen absorption / desorption temperature is 30℃, the hydrogen absorption amount is 2.05H / M, the hydrogen desorption amount is 0.66H / M, the hydrogen absorption plateau pressure is 2.29bar, and the hydrogen desorption plateau pressure is 0.01bar;

[0125] Under the condition that the hydrogen absorption / desorption temperature is 50℃, the hydrogen absorption amount is 2.02H / M, the hydrogen desorption amount is 1.48H / M, the hydrogen absorption plateau pressure is 2.60bar, and the hydrogen desorption plateau pressure is 0.06bar;

[0126] Under the condition that the hydrogen absorption / desorption temperature is 70℃, the hydrogen absorption amount is 2.02H / M, the hydrogen desorption amount is 1.61H / M, the hydrogen absorption plateau pressure is 6.08bar, and the hydrogen desorption plateau pressure is 0.18bar.

[0127] The test result shows that within the range of 30-70℃ of the hydrogen absorption / desorption temperature, the temperature has no significant effect on the hydrogen absorption amount, but increasing the temperature can increase the hydrogen desorption amount, and can also increase the hydrogen absorption plateau pressure and the hydrogen desorption plateau pressure.

[0128] The XRD test result of the TCNV-4 / 6-D is shown in Figure 5 As shown in the figure, the TCNV-4 / 6-D only has one characteristic peak of BCC structure. The test result shows that the TCNV-4 / 6-D is a single-phase BCC structure. In comparison with the XRD test result of the TCNV-4 / 6, it can be known that the TCNV-4 / 6 can restore the single-phase BCC structure after hydrogen absorption / desorption.

[0129] By comparing the comparative example 4 and the example 1, it can be known that when the molar ratio of (Ti+Cr) to (Nb+V) is 40:60, the TiCrNbV high-entropy hydrogen storage alloy can be obtained.

Claims

1. A TiCrNbV high entropy hydrogen storage alloy with a BCC structure, characterized by: The general formula of high entropy hydrogen storage alloy is (TiCr) x (NbV) y , wherein 5≤x / 2≤40at.%, 5≤y / 2≤40at.%, and x+y=100at.%, and the atomic ratios of Ti and Cr are the same, and the atomic ratios of Nb and V are the same; The valence electron concentration of TiCrNbV high entropy hydrogen storage alloy is always 5; The lattice distortion of the TiCrNbV high entropy hydrogen storage alloy is 4%≤δ≤5.5%.

2. The TiCrNbV high entropy hydrogen storage alloy according to claim 1, characterized in that: The high entropy hydrogen storage alloy has a single-phase BCC structure before absorbing hydrogen and can still recover to the single-phase BCC structure after releasing hydrogen.

3. A method for preparing a TiCrNbV high entropy hydrogen storage alloy, characterized in that The method comprises the following steps: firstly, arc melting metal elements of Ti, Cr, Nb and V with a certain molar ratio of Ti, Cr, Nb and V being satisfied; after the melting is completed, the molten alloy is poured into a water-cooled copper mold to obtain a TiCrNbV high-entropy hydrogen storage alloy ingot; then, mechanically crushing and sieving the ingot to obtain alloy powder; finally, activating the alloy powder to obtain a TiCrNbV high-entropy hydrogen storage alloy for hydrogen storage.

4. The preparation method according to claim 4, characterized in that: The arc melting conditions are as follows: high-purity argon is used as the protective gas, electromagnetic stirring is performed during melting, the melting current is 200-450A, the melting time is 10-100s / time, the number of melting times is 5 times, and the particles are turned over after each melting and cooling; the screening conditions are as follows: the particle size requirement is 50-300 mesh.

5. The preparation method according to claim 4, characterized in that: The activation conditions are as follows: a two-step activation method is adopted, wherein the conditions for the first step of activation are as follows: an activation temperature of 20-50°C, an activation hydrogen pressure of 1-20 bar, and an activation time of 0.15-2h; The activation conditions of the second step are as follows: activation temperature 300-600° C., activation hydrogen pressure 0.0005-0.005 bar, and activation time 0.5-4 h.

6. The preparation method according to claim 4, characterized in that: The obtained TiCrNbV high entropy hydrogen storage alloy has a maximum hydrogen absorption capacity of 1.9-2.1H / M and a maximum hydrogen desorption capacity of 1.4-1.7H / M within the hydrogen absorption / desorption temperature range of 30-70°C; the hydrogen absorption platform pressure reaches 10-40 bar, and the hydrogen desorption platform pressure reaches 0.03-1 bar.

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