A cheap, high-capacity, high-entropy hydrogen storage alloy and its preparation method

Abstract

The present invention provides a cheap high-capacity high-entropy hydrogen storage alloy and a preparation method thereof. The hydrogen storage alloy is composed of five elements, namely vanadium, titanium, chromium, iron, and manganese. Its chemical formula composition is in terms of molar ratio: V a Ti b Cr c Fe d Mn e , where 34 ≤ a ≤ 36, 34 ≤ b ≤ 36, 9 ≤ c ≤ 11, 9 ≤ d ≤ 11, 9 ≤ e ≤ 11, a + b + c + d + e = 100. This alloy solves the problems of high cost and poor hydrogen absorption kinetics of vanadium-titanium-based solid solution alloys. This hydrogen storage alloy belongs to a solid solution high-entropy alloy and has ultra-fast hydrogen absorption kinetics performance, high hydrogen absorption capacity, easy activation, low cost, and a traditional and simple production method.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen storage alloys, and in particular to a low-cost, high-capacity and ultrafast hydrogen absorption high-entropy hydrogen storage alloy and a preparation method thereof, and in particular to a high-entropy solid solution hydrogen storage alloy composed of multiple elements such as vanadium, titanium, chromium, iron and manganese and a preparation method thereof. Background Art

[0002] The main energy source for human survival has been developing with the development of social activities. Today's world is heavily dependent on fossil fuels (coal, oil, natural gas, etc.). Since 1950, population growth and improved lifestyles have led to a rapid increase in energy demand. It is estimated that it will reach a peak by 2035. With the development of society, energy shortages and large amounts of greenhouse gas emissions have become more and more serious in the process of fossil fuel consumption, which greatly restricts the green and sustainable development of the economy. Therefore, the search for sustainable and clean energy has become the pursuit of scientists. There are many renewable energy sources on the earth, such as solar energy, wind energy, tidal energy, biomass energy, wave energy, and geothermal energy, which are being explored and studied in depth. Among these potential candidates, hydrogen is considered to be the best energy carrier to meet the overall CO2 reduction target because of its high energy density (120MJ / kg), environmental protection, and high abundance on the earth.

[0003] Hydrogen is a flammable and explosive active gas. In the entire hydrogen energy industry chain of "production, storage, transmission, and use", hydrogen storage is a key link in the "hydrogen economy", so it is necessary to develop a safe, low-cost, and compact hydrogen storage system. Hydrogen storage methods mainly include gaseous, liquid, and solid hydrogen storage. In contrast, solid-state hydrogen storage is considered to be the direction of large-scale hydrogen energy storage and transportation in the future due to its advantages such as safe storage, convenient transportation, and high storage density.

[0004] Metal hydride solid hydrogen storage has the advantages of high hydrogen storage density, good safety, convenient operation and low operating cost, and is considered to be the most ideal hydrogen storage method. Vanadium-titanium based BCC (Body Centred Cubic) structural alloys as hydrogen storage materials have the advantages of high hydrogen storage density, good anti-powdering performance, and the ability to absorb and release hydrogen at room temperature and pressure. The vanadium-titanium based hydrogen storage alloys currently developed are mainly V-Ti-Mn, V-Ti-Cr, V-Ti-Fe, and V-Ti-Ni series multi-component alloys. Among them, the V-Ti-Cr series alloys have high capacity, good cycle performance and hydrogen absorption and desorption kinetics, and are considered to be the most promising candidate materials. However, in order to maintain high capacity, the existing vanadium-titanium based solid solution alloys have a high proportion of the expensive vanadium element, and cost has become a major problem hindering their application. Moreover, the hydrogen absorption kinetics are poor, and it takes at least 5 minutes for hydrogen absorption to reach saturation. For example, XBYu et al. reported that the hydrogen storage alloy V-Ti-Fe alloy takes 10 minutes to absorb hydrogen (XBYu, ZXYang, SLFeng, Z.Wu, NX Xu. Influence of Fe addition on hydrogen storage characteristics of Ti-V-based alloy [J]. Int. J. Hydrogen Energy, 2006, 31: 1176-1181. https: / / doi.org / 10.1016 / j.ijhydene.2005.09.008); JBZhu et al. reported in 2015 that the hydrogen storage alloy Ti-V-Cr-Mn takes more than 7 minutes to absorb hydrogen (JBZhu, LQMa, F.Liang, LMWang, Effect of Sc substitution on hydrogen storage properties of Ti-V-Cr-Mn alloys [J]. Int. J. Hydrogen Energy, 2015, 40: 6860-6865. https: / / doi.org / 10.1016 / j.ijhydene.2015.03.149); the Chinese invention patent with the authorization number of ZL 201910189586.3 and the name of “Multiphase hydrogen storage alloy with high hydrogen desorption efficiency and its preparation method and application” has solved the problems of hydrogen absorption kinetics and hydrogen desorption efficiency of vanadium-based solid solution hydrogen storage alloy to a certain extent, but the hydrogen absorption capacity of the alloy is relatively low.

[0005] Therefore, how to realize a vanadium-titanium based BCC structured solid solution hydrogen storage alloy with low cost, high capacity and fast hydrogen absorption kinetics is a problem that researchers have to solve. High entropy alloys (High entropy alloys, containing at least five main elements, each with an atomic percentage in the range of 5% to 35%) have received increasing attention in the materials science community due to their unique physical and chemical properties. So far, most research on high entropy alloys has focused on their potential applications as structural materials. In fact, in addition to being structural materials, high entropy alloys may also have great prospects in functional materials. Compared with traditional metal compounds, high entropy can promote the formation of a single-phase solid solution structure with severe lattice deformation (strain). Lattice deformation forms more suitable reaction sites, which may facilitate gas absorption, resulting in good performance. Summary of the invention

[0006] The invention provides a low-cost BCC structure solid solution high entropy hydrogen storage alloy with high capacity and ultrafast hydrogen absorption kinetics.

[0007] The embodiment of the present invention provides a hydrogen storage alloy, which is composed of five elements: vanadium, titanium, chromium, iron, and manganese, and its chemical formula composition is calculated by molar ratio: V a Ti b Cr c Fe d Mn e , among which, 34≤a≤36, 34≤b≤36, 9≤c≤11, 9≤d≤11, 9≤e≤11, a+b+c+d+e=100.

[0008] Preferably, the chemical formula composition of the hydrogen storage alloy is calculated in molar ratio: 35 Ti 35 Cr 10 Fe 10 Mn 10 .

[0009] It is preferred that the hydrogen storage alloy has a solid solution phase of a BCC structure, wherein the proportion of the solid solution phase of the BCC structure is 97% or more.

[0010] Preferably, the hydrogen storage alloy has a hydrogen absorption capacity of 3.27 wt % or more at room temperature.

[0011] Preferably, the time required for the hydrogen storage alloy to absorb hydrogen to reach 90% of the saturation amount at room temperature is 77 seconds or less.

[0012] The present invention also provides a method for preparing the hydrogen storage alloy described in any one of the above items, the method comprising the following steps:

[0013] S1: The ingredients are prepared according to the chemical formula, and the purity of the metal element raw materials used for the preparation is above 99.5%;

[0014] S2: melting the raw materials under a protective atmosphere;

[0015] S3: After the smelting is completed, the furnace body is naturally cooled to obtain the alloy.

[0016] Preferably, the smelting is carried out in a non-consumable vacuum arc furnace.

[0017] Preferably, the protective atmosphere comprises argon.

[0018] Preferably, the invention is characterized in that, in order to ensure uniform alloy, the melting is turned over 3-10 times in step S2.

[0019] The beneficial effects of the present invention are:

[0020] 1) The low-cost, high-capacity and ultrafast hydrogen absorption high-entropy hydrogen storage alloy described in the present invention utilizes high entropy to promote the formation of a single phase of a BCC structure solid solution, and the lattice has severe distortion, which produces more and more suitable reaction sites, which is conducive to gas absorption, thereby having a high capacity.

[0021] 2) The low-cost, high-capacity and ultrafast hydrogen absorption high-entropy hydrogen storage alloy of the present invention has a large atomic size difference, which results in a relatively serious lattice distortion. The serious lattice distortion leads to a diffusion hysteresis of alloy atoms, inhibits the growth of alloy grains, forms nano-grains, greatly increases the grain boundary density, and provides more channels for the diffusion of hydrogen atoms, thereby greatly improving the kinetic performance of hydrogen absorption and desorption.

[0022] 3) The low-cost, high-capacity and ultrafast hydrogen absorption high-entropy hydrogen storage alloy of the present invention has a low vanadium content and cheap iron, manganese, foamed titanium, etc. are added to the alloy, so the cost is low, the alloy is easy to activate, the production method is simple, and it is suitable for hydrogen storage tanks, hydrogen purification, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0024] Figure 1 It is the X-ray diffraction pattern of Example.

[0025] Figure 2 1 is the hydrogen absorption kinetic curve of the embodiment.

[0026] Figure 3 It is the PCT curve of Example. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0028] Embodiment 1

[0029] Press V 34 Ti 36 Cr 10 Fe 10 Mn 10 The alloy formula is determined by the weight percentage for batching. The metal raw materials used in the experiment are all above 99.5%, and then melted in a non-consumable vacuum arc furnace under an argon protective atmosphere. In order to ensure uniform composition, the alloy ingot is turned over and melted three times and cooled to room temperature with the furnace. After the outer surface of the ingot is polished and ground, it is mechanically crushed and sieved through 200 mesh. 5g of alloy powder is weighed for X-ray phase analysis, and 2g of alloy powder is weighed and loaded into the stainless steel reaction container of the homemade Sieverts PCT tester. After complete activation, hydrogen absorption kinetics tests at room temperature and PCT determinations in the hydrogen pressure range of 0.02-5MPa are carried out. The data are listed in Table 1 below.

[0030] Table 1 Alloy hydrogen storage properties

[0031]

[0032] Note: C abs —Hydrogen absorption (wt.%); C des —hydrogen release amount (wt.%); P eq is the platform pressure (MPa).

[0033] The alloy has a solid solution phase with a BCC structure, and the proportion of the BCC solid solution phase exceeds 97%. It only takes 70 seconds for the alloy to absorb 90% of the saturated amount of hydrogen at 295K, showing ultra-fast hydrogen absorption kinetics. In addition, the data in Table 1 show that the hydrogen absorption capacity of the alloy of the present invention is as high as 3.30wt.%. Compared with similar solid solution alloys at home and abroad, the above performance is significantly superior in hydrogen absorption capacity and hydrogen absorption kinetics.

[0034] Embodiment 2

[0035] Press V 35 Ti 35 Cr 10 Fe 10 Mn 10The alloy formula is determined by the weight percentage for batching. The metal single substance raw materials used in the experiment are all above 99.5%, and then melted in a non-consumable vacuum arc furnace under argon protective atmosphere. In order to ensure uniform composition, the alloy ingot is turned over and melted 5 times and cooled to room temperature with the furnace. After the outer surface of the ingot is polished and ground, it is mechanically crushed and sieved through 200 mesh. 5g of alloy powder is weighed for X-ray phase analysis, and 2g of alloy powder is weighed and loaded into the stainless steel reaction container of the homemade Sieverts PCT tester. After complete activation, hydrogen absorption kinetics tests at room temperature and PCT determinations in the hydrogen pressure range of 0.02-5MPa are carried out. The data are listed in Table 2 below.

[0036] Table 2 Alloy hydrogen storage properties

[0037]

[0038] Note: C abs —Hydrogen absorption (wt.%); C des —hydrogen release amount (wt.%); P eq is the platform pressure (MPa).

[0039] Figure 1 This is the phase analysis spectrum of the alloy. It can be seen that the alloy has a solid solution phase with a BCC structure, and the proportion of the BCC solid solution phase exceeds 97%; Figure 2 It is the hydrogen absorption kinetics of the alloy at 295K. It can be seen that it only takes 77 seconds for the alloy to absorb 90% of the saturation amount of hydrogen at 295K, showing ultra-fast hydrogen absorption kinetics. Figure 3 The PCT diagram of the alloy is shown in Table 2. In addition, the data in Table 2 show that the hydrogen absorption capacity of the alloy of the present invention at 295K is as high as 3.27wt.%. Compared with similar solid solution alloys at home and abroad, the above performance is significantly superior in hydrogen absorption capacity and hydrogen absorption kinetics.

[0040] Embodiment 3

[0041] Press V 35 Ti 35 Cr9Fe 11 Mn 10 The alloy formula is determined by the weight percentage for batching. The metal single substance raw materials used in the experiment are all above 99.5%, and then melted in a non-consumable vacuum arc furnace under argon protective atmosphere. In order to ensure uniform composition, the alloy ingot is turned over and melted 7 times and cooled to room temperature with the furnace. After the outer surface of the ingot is polished and ground, it is mechanically crushed and sieved through 200 mesh. 5g of alloy powder is weighed for X-ray phase analysis, and 2g of alloy powder is weighed and loaded into the stainless steel reaction container of the homemade Sieverts PCT tester. After complete activation, hydrogen absorption kinetics tests at room temperature and PCT determinations in the hydrogen pressure range of 0.02-5MPa are carried out. The data are listed in Table 3 below.

[0042] Table 3 Alloy hydrogen storage properties

[0043]

[0044] Note: C abs —Hydrogen absorption (wt.%); C des —hydrogen release amount (wt.%); P eq is the platform pressure (MPa).

[0045] The alloy has a solid solution phase with a BCC structure, and the proportion of the BCC solid solution phase exceeds 97%. The alloy only takes 73 seconds to absorb 90% of the saturated hydrogen at 295K, showing ultra-fast hydrogen absorption kinetics. In addition, the data in Table 3 show that the room temperature hydrogen absorption capacity of the alloy of the present invention is as high as 3.35wt.%. The above performance is significantly superior to similar solid solution alloys at home and abroad in terms of hydrogen absorption capacity and hydrogen absorption kinetics.

[0046] Embodiment 4

[0047] Press V 35 Ti 35 Cr 10 Fe9Mn 11 The alloy formula is determined by the weight percentage for batching. The metal single substance raw materials used in the experiment are all above 99.5%, and then melted in a non-consumable vacuum arc furnace under argon protective atmosphere. In order to ensure uniform composition, the alloy ingot is turned over and melted 10 times and cooled to room temperature with the furnace. After the outer surface of the ingot is polished and ground, it is mechanically crushed and sieved through 200 mesh. 5g of alloy powder is weighed for X-ray phase analysis, and 2g of alloy powder is weighed and loaded into the stainless steel reaction container of the homemade Sieverts PCT tester. After complete activation, hydrogen absorption kinetics tests at room temperature and PCT determinations in the hydrogen pressure range of 0.02-5MPa are carried out. The data are listed in Table 4 below.

[0048] Table 4 Alloy hydrogen storage properties

[0049]

[0050] Note: C abs —Hydrogen absorption (wt.%); C des —hydrogen release amount (wt.%); P eq is the platform pressure (MPa).

[0051] The alloy has a solid solution phase with a BCC structure, and the proportion of the BCC solid solution phase exceeds 97%. The alloy only takes 75 seconds to absorb 90% of the saturated amount of hydrogen at 295K, showing ultra-fast hydrogen absorption kinetics. In addition, the data in Table 4 show that the room temperature hydrogen absorption capacity of the alloy of the present invention is as high as 3.30wt.%. The above performance is significantly superior to similar solid solution alloys at home and abroad in terms of hydrogen absorption capacity and hydrogen absorption kinetics.

[0052] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations shall all fall within the scope defined by the appended claims.

Claims

1. A hydrogen storage alloy, characterized in that The hydrogen storage alloy is composed of five elements: vanadium, titanium, chromium, iron and manganese. The chemical formula of the alloy is as follows in terms of molar ratio: V a Ti b Cr c Fe d Mn e , where 34≤ a ≤36, 34≤ b ≤36,9≤ c ≤11,9≤ d ≤11,9≤ e ≤11, a + b + c + d + e =100.

2. The hydrogen storage alloy according to claim 1, characterized in that The chemical formula composition of the hydrogen storage alloy is calculated by molar ratio: 35 Ti 35 Cr 10 Fe 10 Mn 10 .

3. The hydrogen storage alloy according to claim 1 or 2, characterized in that: The hydrogen storage alloy has a solid solution phase with a BCC structure, wherein the proportion of the solid solution phase with the BCC structure is greater than 97%.

4. The hydrogen storage alloy according to claim 1 or 2, characterized in that: The hydrogen storage alloy has a hydrogen absorption capacity of more than 3.27 wt % at room temperature.

5. The hydrogen storage alloy according to claim 1 or 2, characterized in that: The time required for the hydrogen storage alloy to absorb hydrogen to 90% of the saturation amount at room temperature is less than 77 seconds.

6. The method for preparing the hydrogen storage alloy according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: S1: The ingredients are prepared according to the chemical formula, and the purity of the metal element raw materials used for the preparation is above 99.5%; S2: melting the raw materials under a protective atmosphere; S3: After the smelting is completed, the furnace body is naturally cooled to obtain the alloy.

7. The method according to claim 6, characterized in that The smelting is carried out in a non-consumable vacuum arc furnace.

8. The method according to any one of claims 6-7, characterized in that: The protective atmosphere includes argon.

9. The method according to any one of claims 6-7, characterized in that: To ensure uniform alloy, the alloy is turned over and melted 3-10 times in step S2.

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