A hydrogen storage alloy, its preparation method and application

Abstract

The present invention provides a hydrogen storage alloy, and the chemical general formula of the hydrogen storage alloy is: Y<subgt;1-a-b< / subgt>Mg<subgt;aM<subgt;bNi<subgt>xMn<subgt>yA<subgt>z, where M includes at least one of La and Ce, A includes at least one of Co, Al, and Fe, 0.15 ≤ a ≤ 0.3, 0.05 ≤ b ≤ 0.15, 3.35 ≤ x ≤ 3.5, 0.25 ≤ y ≤ 0.45, and 0 ≤ z ≤ 0.2. The structure phases of the hydrogen storage alloy of the present invention are A<subgt>2B<subgt>7 phase and A<subgt>5B<subgt>19 phase. Compared with the currently widely used AB<subgt>5 type rare earth hydrogen storage alloy, the hydrogen storage alloy of the present invention exhibits excellent hydrogen storage capacity, has excellent hydrogen storage density, the hydrogen absorption amount at room temperature can reach more than 1.55 wt%, and the effective hydrogen release amount can reach more than 1.5 wt%.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen storage alloys, and particularly relates to a hydrogen storage alloy, a preparation method thereof, and an application thereof. Background Art

[0002] As one of the most promising clean energy sources in the 21st century, hydrogen energy is regarded as a key carrier for achieving the carbon neutrality goal due to its high energy density, wide sources, and zero carbon emission characteristics. As an energy supply node for hydrogen fuel cell vehicles, one of the core technical challenges of a hydrogen refueling station lies in the storage and compression of hydrogen. Since the volumetric energy density of hydrogen is extremely low, only 3 kWh / m³ under normal pressure, it needs to be compressed to a high pressure of 35 - 70 MPa to improve the storage and transportation efficiency. This process relies on an efficient and reliable hydrogen compressor, and the performance of the hydrogen compressor directly determines the energy consumption, cost, and safety of the hydrogen refueling station.

[0003] Most of the existing hydrogen refueling stations mainly use mechanical compressors (such as piston type and diaphragm type), which compress hydrogen step by step through mechanical motion. Although the technology is mature, its inherent defects are significant: low energy efficiency, high maintenance cost, poor safety, and high noise. To increase its hydrogenation pressure and compression ratio, several different hydrogen compression materials are usually connected in series to design a multi-stage hydrogen compressor. A three-stage metal hydride compressor is generally divided into two parts. The first part is a low-pressure high-density hydrogen storage device, and the second part is a primary, intermediate, and final three-stage hydrogen compression device. By jointly using these two parts of the device, the hydrogen pressure can be increased from 3 - 4 MPa to more than 85 MPa, realizing hydrogen filling for 35 MPa or 70 MPa hydrogen storage cylinders.

[0004] It is reported that currently, the hydrogen storage materials used in low-pressure high-density hydrogen storage devices and primary hydrogen compression devices are mainly AB5-type rare earth hydrogen storage materials, whose structure is of the CaCu5 type, and the typical hydride is LaNi5H6. Limited by the structure limitation theory, its maximum hydrogen storage capacity is only about 1.4 wt%, which cannot meet the current demand for high hydrogen storage capacity. Moreover, due to the structure limitation of the AB5-type alloy, the hydrogen storage capacity of the AB5-type rare earth hydrogen storage materials applicable to metal hydride hydrogen compressors is relatively low. Since the existing hydrogen storage materials are difficult to meet the current application requirements, it has hindered the further development of hydrogen storage materials.

[0005] Therefore, it is of great significance to develop a new type of hydrogen storage material applicable to metal hydride hydrogen compressors. Summary of the Invention

[0006] In the first aspect of the present invention, a hydrogen storage alloy is provided, and the chemical general formula of the hydrogen storage alloy is: Y 1-a- b Mg a M b Nix Mn y A z , wherein, M includes at least one of La and Ce, A includes at least one of Co, Al, and Fe, 0.15 ≤ a ≤ 0.3, 0.05 ≤ b ≤ 0.15, 3.35 ≤ x ≤ 3.5, 0.25 ≤ y ≤ 0.45, and 0 ≤ z ≤ 0.2.

[0007] Through the optimized design of each element, at least one of the rare earth elements La and Ce is doped in the hydrogen storage alloy, and the ratio of each element in the alloy is regulated, so that the obtained rare earth hydrogen storage alloy has excellent hydrogen storage performance.

[0008] The inventors found that when the Mg content is too low, although the hydrogen storage capacity can be increased, the hydrogen desorption platform pressure will be reduced, resulting in a decrease in the effective hydrogen desorption amount. When the Mg content is too high, the unit cell volume of the phase will decrease, although the hydrogen desorption platform pressure can be increased, but the hydrogen storage capacity will be reduced, resulting in a decrease in the effective hydrogen desorption amount. Therefore, it is necessary to control the Mg content within a reasonable range, which can increase the hydrogen desorption platform pressure of the alloy and further increase the effective hydrogen desorption amount while ensuring a certain hydrogen absorption amount (hydrogen storage capacity).

[0009] When the Ni content is too low, the content of the A2B7-type phase will increase, and the unit cell volume of the phase will increase. Although the hydrogen storage capacity can be increased, the hydrogen desorption platform pressure will be reduced. When the Ni content is too high, the AB5-type phase will appear, resulting in a decrease in the unit cell volume of the phase and thus a decrease in the hydrogen absorption amount of the alloy. Therefore, it is necessary to control the Ni content within a reasonable range.

[0010] Although Mn can increase the hydrogen storage capacity of the alloy and optimize the platform characteristics, when the Mn content is too low, the hydrogen storage capacity of the alloy will decrease, the slope factor will increase, and the hydrogen desorption platform will tilt. When the Mn content is too high, the large atomic radius of Mn will reduce the hydrogen desorption platform pressure of the alloy. Although the slope factor can be reduced, the effective hydrogen desorption amount will be reduced. Therefore, it is necessary to control the Mn content within a reasonable range.

[0011] The atomic radii of Ce and La are larger than that of Y. When Ce or La is used to replace Y on the A side, the unit cell volume of the phase in the alloy will increase, and the hydrogen absorption capacity of the alloy will be improved. However, when the content of Ce or La is too low, the hydrogen absorption capacity of the alloy cannot be effectively improved. When the content of Ce or La is too high, although the unit cell volume of the phase will be larger, the atomic masses of Ce (140.1) and La (138.9) are greater than that of Y (88.91), which will significantly reduce the hydrogen absorption capacity of the alloy, and may even cause a significant increase in the slope factor and a significant decrease in the effective hydrogen desorption amount. It should be noted that if the slope factor is too large, in the actual application process, it will lead to the complication of the pressure control of the hydrogen storage system, the instability of the hydrogen release rate, and greatly increase the operation difficulty and cost. Therefore, the content of Ce or La needs to be controlled within a reasonable range. It should be noted that if the slope factor is too large, in the actual application process, it will lead to the complication of the pressure control of the hydrogen storage system, the instability of the hydrogen release rate, and greatly increase the operation difficulty and cost.

[0012] In the present invention, the proportion of Mg element in the hydrogen storage alloy is 0.15 ≤ a ≤ 0.3, for example, it can be 0.15, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28 or 0.3, etc.; the proportion of M element in the hydrogen storage alloy is 0.05 ≤ b ≤ 0.15, for example, it can be 0.05, 0.07, 0.09, 0.11, 0.13 or 0.15, etc.; the proportion of Ni element in the hydrogen storage alloy is 3.35 ≤ x ≤ 3.5, for example, it can be 3.35, 3.37, 3.39, 3.41, 3.43, 3.45, 3.47, 3.49 or 3.5, etc.; the proportion of Mn element in the hydrogen storage alloy is 0.25 ≤ y ≤ 0.45, for example, it can be 0.25, 0.27, 0.29, 0.31, 0.33, 0.35, 0.37, 0.39, 0.41, 0.43 or 0.45, etc.; the proportion of A element in the hydrogen storage alloy is 0 ≤ z ≤ 0.2, for example, it can be 0, 0.03, 0.05, 0.1, 0.13, 0.15 or 0.2, etc., but not limited to the listed values, and other unlisted values within this range are also applicable.

[0013] In some embodiments, 0.15 ≤ a ≤ 0.25, 0.1 ≤ b ≤ 0.15, 3.35 ≤ x ≤ 3.4, 0.3 ≤ y ≤ 0.4, 0 ≤ z ≤ 0.1.

[0014] In some embodiments, the hydrogen absorption amount of the hydrogen storage alloy at room temperature ≥ 1.55 wt%, the effective hydrogen desorption amount of the hydrogen storage alloy ≥ 1.5 wt%, and the room temperature is 25 °C.

[0015] In the present invention, the plateau pressure of the hydrogen storage alloy during the hydrogen absorption and desorption process ≥ 0.1 MPa, which can ensure the effective hydrogen desorption amount in the actual application.

[0016] In some embodiments, the structural phase of the hydrogen storage alloy is the A2B7 phase and the A5B 19 phase.

[0017] Currently, in low-pressure high-density hydrogen storage devices and primary hydrogen compression devices, the hydrogen storage materials used are mainly AB5-type rare earth hydrogen storage materials, whose structure is of the CaCu5 type, and the typical hydride is LaNi5H6. Limited by the structural limitation theory, its hydrogen storage capacity is limited and cannot meet the current demand for high hydrogen storage capacity. By adjusting the ratio of each element in the alloy, the present invention enables the alloy to have a mixed-phase structure of the A2B7 type and the A5B 19 type, and the prepared alloy has a hydrogen absorption amount of ≥1.55 wt% and an effective hydrogen release amount of ≥1.5 wt%, showing the potential to replace AB5-type hydrogen storage alloys.

[0018] In some embodiments, the hydrogen storage alloy includes Y 0.75 Mg 0.15 La 0.1 Ni 3.4 Mn 0.3 , Y 0.68 Mg 0.22 Ce 0.1 Ni 3.38 Mn 0.35 Co 0.05 and Y 0.6 Mg 0.25 La 0.15 Ni 3.35 Mn 0.4 Al 0.05 Fe 0.05 at least one of them.

[0019] In a second aspect of the present invention, there is provided a method for preparing the above hydrogen storage alloy, including the following steps: weighing and mixing raw materials according to the stoichiometric ratio of the chemical formula Y 1-a-b Mg a M b Ni x Mn y A z , and obtaining the hydrogen storage alloy through melting and annealing treatments. Among them, the raw materials can be the simple substances of each metal element or the master alloys of metal elements. For example, Y-Ni alloys, Y-Mg, Y-Mn alloys, etc., but are not limited to the listed alloy combinations.

[0020] In some embodiments, the melting is carried out by an intermediate frequency induction melting method.

[0021] In some embodiments, the annealing step includes: heating from room temperature to 450-550°C at a heating rate of 3-7°C / min, then heating to 650-750°C at a heating rate of 1-3°C / min, then heating to 950-1010°C at a heating rate of 1-3°C / min, keeping warm for 6-18 hours, and cooling.

[0022] In some embodiments, the annealing step includes: heating from room temperature to 500°C at a heating rate of 5°C / min, then heating to 700°C at a heating rate of 2°C / min, then heating to 950-1010°C at a heating rate of 1°C / min, keeping warm for 6-18 hours, and cooling.

[0023] In a third aspect, the present invention provides a hydrogen storage device comprising the above-mentioned hydrogen storage alloy.

[0024] In a fourth aspect, the present invention provides a hydrogen storage system comprising the above-mentioned hydrogen storage device.

[0025] Compared with the prior art, the present invention has the following beneficial effects: the structural phases of the hydrogen storage alloy of the present invention are A2B7 phase and A5B 19 Compared with the currently widely used AB5 type rare earth hydrogen storage alloy, the hydrogen storage alloy of the present invention exhibits excellent hydrogen storage capacity and excellent hydrogen storage density. The hydrogen absorption capacity at room temperature can reach more than 1.55wt%, and the effective hydrogen release capacity can reach more than 1.5wt%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the pressure-composition-temperature (PCT) curve of Example 1.

[0027] Figure 2 This is the van't Hoff fitting curve of Example 1. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below through specific examples. The specific examples do not limit the scope of protection of the present invention. Some non-essential modifications and adjustments made by others based on the concept of the present invention still fall within the scope of protection of the present invention. The raw materials, reagents or devices used in the examples can be obtained from conventional commercial channels or can be obtained by existing technical methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0029] The raw materials used in the embodiments and comparative examples of the present invention include metal elements Y, Mg, La, Ce, Ni, Mn, Co, Al, Fe, Si, Zn, and Gd.

[0030] Example 1: Y 0.75 Mg 0.15 La0.1 Ni 3.4 Mn 0.3

[0031] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, elemental metals Y, Mg, La, Ni, and Mn were used as raw materials for proportioning, and an as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process is as follows: Heat from room temperature to 500 °C at a heating rate of 5 °C / min, then increase the temperature to 700 °C at a heating rate of 2 °C / min, and then increase the temperature to 950 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and hydrogen storage alloy Y was obtained. 0.75 Mg 0.15 La 0.1 Ni 3.4 Mn 0.3 。

[0032] Performance test of hydrogen storage alloy: The obtained alloy was crushed, and about 1.5 g of alloy powder was taken for pressure-composition-temperature (PCT) test. The test temperatures were set at 25 °C, 40 °C, and 55 °C, and the hydrogen pressure range was 0 - 10 MPa. The test results showed ( Figure 1 、 Figure 2 ), that at 25 °C, the hydrogen absorption amount of this alloy was 1.65 wt%, the dehydrogenation platform pressure was 0.21 MPa, and the effective dehydrogenation amount reached 1.51 wt%. The slope factor S f of the dehydrogenation platform was calculated by the formula: S f = In(P60% / P25%) / (60%Cmax - 25%Cmax). Through calculation, the slope factor S f in this example was 0.87. Using the dehydrogenation platform pressure at different test temperatures, the dehydrogenation enthalpy change of this alloy was calculated to be 37.43 kJ / mol by the van’t Hoff formula, and it was extrapolated that at 120 °C, the dehydrogenation pressure of the alloy was expected to reach 8.11 MPa. The alloy powder less than 400 mesh was characterized by XRD and analyzed by the Rietveld method. The results showed that the alloy phase composition was A2B7 type phase and A5B 19 type phase, and their phase contents were 80.76% and 19.24% respectively.

[0033] Example 2: Y 0.68 Mg 0.22 Ce 0.1 Ni 3.38 Mn 0.35 Co 0.05

[0034] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, metallic elements Y, Mg, Ce, Ni, Mn, and Co were used as raw materials for proportioning, and an as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process was as follows: It was heated from room temperature to 500 °C at a heating rate of 5 °C / min, then raised to 700 °C at a heating rate of 2 °C / min, and then increased to 970 °C at a heating rate of 1 °C / min. After maintaining this temperature for 12 hours, it was cooled to room temperature with the furnace, and hydrogen storage alloy Y was obtained. 0.68 Mg 0.22 Ce 0.1 Ni 3.38 Mn 0.35 Co 0.05 。

[0035] The testing method of Example 2 was the same as that of Example 1. The results showed that at 25 °C, the hydrogen absorption amount of the alloy was 1.58 wt%, the hydrogen desorption platform pressure was 0.31 MPa, the effective hydrogen desorption amount was 1.52 wt%, and the slope factor S of the hydrogen desorption platform f was 0.62. Using the hydrogen desorption platform pressure at different temperatures, the hydrogen desorption enthalpy change of the alloy was calculated to be 33.47 kJ / mol by using the van’t Hoff formula, and it was extrapolated that at 120 °C, the hydrogen desorption pressure of the alloy was expected to reach 8.20 MPa. The structural analysis showed that the phase composition of the alloy was A2B7-type phase and A5B 19 type phase, and their phase contents were 75.36% and 24.64% respectively.

[0036] Example 3: Y 0.6 Mg 0.25 La 0.15 Ni 3.35 Mn 0.4 Al 0.05 Fe 0.05

[0037] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, metallic elements Y, Mg, La, Ni, Mn, Al, and Fe were used as raw materials for proportioning, and an as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process was as follows: It was heated from room temperature to 500 °C at a heating rate of 5 °C / min, then raised to 700 °C at a heating rate of 2 °C / min, and then increased to 1000 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and hydrogen storage alloy Y was obtained. 0.6 Mg 0.25 La 0.15 Ni 3.35Mn 0.4 Al 0.05 Fe 0.05 。

[0038] The testing method of Example 3 is the same as that of Example 1. The results show that at 25 °C, the hydrogen absorption amount of the alloy is 1.55 wt%, the hydrogen desorption platform pressure is 0.28 MPa, the effective hydrogen desorption amount is 1.50 wt%, and the slope factor S of the hydrogen desorption platform f is 0.75. Using the hydrogen desorption platform pressure at different temperatures, the hydrogen desorption enthalpy change of the alloy is calculated to be 34.58 kJ / mol by using the van’t Hoff formula, and it can be extrapolated that at 120 °C, the hydrogen desorption pressure of the alloy is expected to reach 8.15 MPa. Structure analysis shows that the phase composition of the alloy is A2B7-type phase and A5B 19 type phase, and their phase contents are 73.68% and 26.32% respectively.

[0039] Comparative Example 1: Y 0.8 Mg 0.1 La 0.1 Ni 3.4 Mn 0.3

[0040] Compared with Example 1, the component content of the hydrogen storage alloy is different in Comparative Example 1. The alloy composition of this comparative example is Y 0.8 Mg 0.1 La 0.1 Ni 3.4 Mn 0.3 。

[0041] Preparation of the hydrogen storage alloy: According to the atomic ratio of the designed composition, the metal elements Y, Mg, La, Ni, and Mn are used as raw materials for proportioning, and the as-cast alloy is prepared by medium-frequency induction melting. The as-cast alloy is wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube is placed in a muffle furnace for annealing treatment. The annealing process is as follows: heating from room temperature to 500 °C at a heating rate of 5 °C / min, then rising to 700 °C at a heating rate of 2 °C / min, and then increasing to 950 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it is cooled to room temperature with the furnace, and the hydrogen storage alloy Y 0.8 Mg 0.1 La 0.1 Ni 3.4 Mn 0.3 。

[0042] The testing method of Comparative Example 1 is the same as that of Example 1.

[0043] The results show that: at 25 °C, the hydrogen absorption amount of the alloy is 1.67 wt%, the hydrogen desorption platform pressure is 0.12 MPa, the effective hydrogen desorption amount is 1.45 wt%, and the slope factor S of the hydrogen desorption platformf Using the hydrogen desorption plateau pressure at different temperatures, the hydrogen desorption enthalpy of the alloy was calculated to be 39.78 kJ / mol using the van't Hoff equation. By extrapolation, it can be known that the hydrogen desorption plateau pressure of the alloy at 120 °C is 5.8 MPa. Structural analysis shows that the phase composition of the alloy is the A2B7 type phase and the A5B 19 type phase, and the phase contents are 59.12% and 40.88% respectively.

[0044] Comparative Example 2: Y 0.55 Mg 0.35 La 0.1 Ni 3.4 Mn 0.3

[0045] Compared with Example 1, the component content of the hydrogen storage alloy is different. The alloy composition of this comparative example is Y 0.55 Mg 0.35 La 0.1 Ni 3.4 Mn 0.3 .

[0046] Preparation of the hydrogen storage alloy: According to the atomic ratio of the designed composition, the metal elements Y, Mg, La, Ni, and Mn were used as raw materials for proportioning, and the as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process is as follows: heating from room temperature to 500 °C at a heating rate of 5 °C / min, then rising to 700 °C at a heating rate of 2 °C / min, and then increasing to 950 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and the hydrogen storage alloy Y 0.55 Mg 0.35 La<U+ 0.1 Ni 3.4 Mn 0.3 .

[0047] The testing method of Comparative Example 2 is the same as that of Example 1. The results show that at 25 °C, the hydrogen absorption amount of the alloy is 1.45 wt%, the hydrogen desorption plateau pressure is 0.65 MPa, the effective hydrogen desorption amount is 1.38 wt%, and the hydrogen desorption plateau slope factor S f is 0.95. Using the hydrogen desorption plateau pressure at different temperatures, the hydrogen desorption enthalpy of the alloy was calculated to be 25.52 kJ / mol using the van't Hoff equation. By extrapolation, it can be known that the hydrogen desorption plateau pressure of the alloy at 120 °C is 7.83 MPa. Structural analysis shows that the A2B7 type phase and the A5B 19 type phase, and the phase contents are 78.25% and 21.75% respectively.

[0048] Comparative Example 3: Y 0.75 Mg 0.15 La 0.1 Ni 3.3 Mn 0.3

[0049] Compared with Example 1, the component contents of the hydrogen storage alloy are different. The alloy composition of this comparative example is Y 0.75 Mg 0.15 La 0.1 Ni 3.3 Mn 0.3 。

[0050] Preparation of the hydrogen storage alloy: According to the atomic ratio of the designed components, the metal elements Y, Mg, La, Ni, and Mn were used as raw materials for proportioning, and a cast alloy was prepared by medium-frequency induction melting. The cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process was as follows: heated from room temperature to 500 °C at a heating rate of 5 °C / min, then raised to 700 °C at a heating rate of 2 °C / min, and then increased to 1000 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and the hydrogen storage alloy Y was obtained 0.75 Mg 0.15 La 0.1 Ni 3.3 Mn 0.3 。

[0051] The testing method of Comparative Example 3 was the same as that of Example 1. The results showed that at 25 °C, the hydrogen absorption amount of the alloy was 1.68 wt%, the hydrogen desorption plateau pressure was 0.13 MPa, the effective hydrogen desorption amount was 1.43 wt%, and the slope factor S f of the hydrogen desorption plateau was 0.92. Using the hydrogen desorption plateau pressure at different temperatures and the van't Hoff formula, the hydrogen desorption enthalpy change of the alloy was calculated to be 39.22 kJ / mol, and by extrapolation, it was found that the hydrogen desorption plateau pressure of the alloy was 5.95 MPa at 120 °C. Structure analysis showed that there were A2B7-type and A5B 19 -type phases, and the phase contents were 83.73% and 16.27% respectively.

[0052] Comparative Example 4: Y 0.75 Mg 0.15 La 0.1 Ni 3.6 Mn 0.3

[0053] Compared with Example 1, the component contents of the hydrogen storage alloy are different. The alloy composition of this comparative example is Y 0.75 Mg 0.15 La 0.1 Ni3.6 Mn 0.3 。

[0054] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, elemental metals Y, Mg, La, Ni, and Mn are used as raw materials for proportioning, and an as-cast alloy is prepared by medium-frequency induction melting. The as-cast alloy is wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube is placed in a muffle furnace for annealing treatment. The annealing process is as follows: Heat from room temperature to 500 °C at a heating rate of 5 °C / min, then increase the temperature to 700 °C at a heating rate of 2 °C / min, and then increase the temperature to 950 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, cool it to room temperature with the furnace, and the hydrogen storage alloy Y is obtained. 0.75 Mg 0.15 La 0.1 Ni 3.6 Mn 0.3 。

[0055] The test method of Comparative Example 4 is the same as that of Example 1. The results show that at 25 °C, the hydrogen absorption amount of the alloy is 1.39 wt%, the hydrogen desorption platform pressure is 0.55 MPa, the effective hydrogen desorption amount is 1.31 wt%, and the slope factor S of the hydrogen desorption platform f is 0.87. Using the hydrogen desorption platform pressure at different temperatures and calculating with the van’t Hoff formula, the hydrogen desorption enthalpy change of the alloy is calculated to be 27.86 kJ / mol, and by extrapolation, it can be known that the hydrogen desorption platform pressure of the alloy is 8.32 MPa at 120 °C. Structure analysis shows that there are A2B7-type phase, A5B 19 -type phase and AB5-type phase, and the phase contents are 44.33%, 45.36% and 10.31% respectively.

[0056] Comparative Example 5: Y 0.75 Mg 0.15 La 0.1 Ni 3.34 Mn 0.2

[0057] Compared with Example 1, the component content of the hydrogen storage alloy in Comparative Example 5 is different. The alloy composition of this comparative example is Y 0.75 Mg 0.15 La 0.1 Ni 3.34 Mn 0.2 。

[0058] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed components, metal elements Y, Mg, La, Ni, and Mn are used as raw materials for proportioning, and the cast alloy is prepared by medium-frequency induction melting method. The cast alloy is wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube is placed in a muffle furnace for annealing. The annealing process is as follows: heat from room temperature to 500°C at a heating rate of 5°C / min, then increase to 700°C at a heating rate of 2°C / min, and then increase to 950°C at a heating rate of 1°C / min. After maintaining this temperature for 6 hours, cool to room temperature with the furnace to obtain hydrogen storage alloy Y. 0.75 Mg 0.15 La 0.1 Ni 3.34 Mn 0.2 .

[0059] The test method of Comparative Example 5 is consistent with that of Example 1. The results show that at 25°C, the hydrogen absorption capacity of the alloy is 1.46 wt%, the hydrogen desorption platform pressure is 0.31 MPa, the effective hydrogen desorption capacity is 1.39 wt%, and the hydrogen desorption platform slope factor S is 0. f The dehydrogenation platform pressure at different temperatures was used to calculate the dehydrogenation enthalpy of the alloy using the van't Hoff formula to be 33.22 kJ / mol. By extrapolation, it was found that the dehydrogenation platform pressure of the alloy at 120°C was 7.91 MPa. Structural analysis showed that the A2B7 phase and A5B 19 type phase, and the phase contents are 83.23% and 16.77% respectively.

[0060] Comparative Example 6: Y 0.7 Mg 0.15 La 0.1 Ni 3.34 Mn 0.5

[0061] Comparative Example 6 Compared with Example 1, the content of the hydrogen storage alloy is different. The alloy composition of this comparative example is Y 0.7 Mg 0.15 La 0.1 Ni 3.34 Mn 0.5 .

[0062] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, elemental metals Y, Mg, La, Ni, and Mn were used as raw materials for proportioning, and an as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process was as follows: heated from room temperature to 500 °C at a heating rate of 5 °C / min, then raised to 700 °C at a heating rate of 2 °C / min, and then increased to 950 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and hydrogen storage alloy Y was obtained. 0.7 Mg 0.15 La 0.1 Ni 3.34 Mn 0.5 。

[0063] The test method of Comparative Example 6 was the same as that of Example 1. The results showed that at 25 °C, the hydrogen absorption amount of the alloy was 1.56 wt%, the hydrogen desorption platform pressure was 0.11 MPa, the effective hydrogen desorption amount was 1.36 wt%, and the slope factor S of the hydrogen desorption platform f was 0.77. Using the hydrogen desorption platform pressure at different temperatures, the hydrogen desorption enthalpy change of the alloy was calculated to be 39.57 kJ / mol using the van’t Hoff formula, and by extrapolation, it was found that the hydrogen desorption platform pressure of the alloy was 5.21 MPa at 120 °C. Structural analysis showed that there were A2B7-type phase and A5B 19 type phases, and the phase contents were 68.91% and 31.09% respectively.

[0064] Comparative Example 7: Y 0.75 Mg 0.15 Gd 0.1 Ni 3.4 Mn 0.3

[0065] Compared with Example 1, the component content of the hydrogen storage alloy in Comparative Example 7 was different, and the alloy composition of this comparative example was Y 0.75 Mg 0.15 Gd 0.1 Ni 3.4 Mn 0.3 。

[0066] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, elemental metals Y, Mg, Gd, Ni, and Mn were used as raw materials for proportioning, and an as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process was as follows: heating from room temperature to 500 °C at a heating rate of 5 °C / min, then rising to 700 °C at a heating rate of 2 °C / min, and then increasing to 950 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and hydrogen storage alloy Y was obtained. 0.75 Mg 0.15 Gd 0.1 Ni 3.4 Mn 0.3 。

[0067] The testing method of Comparative Example 7 was the same as that of Example 1. The results showed that at 25 °C, the hydrogen absorption amount of the alloy was 1.52 wt%, the hydrogen desorption platform pressure was 0.38 MPa, the effective hydrogen desorption amount was 1.42 wt%, and the slope factor S of the hydrogen desorption platform f was 1.05. Using the hydrogen desorption platform pressure at different temperatures, the hydrogen desorption enthalpy change of the alloy was calculated to be 29.57 kJ / mol using the van’t Hoff formula, and by extrapolation, it was found that the hydrogen desorption platform pressure of the alloy was 6.79 MPa at 120 °C. Structure analysis showed that there were A2B7-type phase and A5B 19 type phases, and the phase contents were 61.25% and 38.75% respectively.

[0068] Comparative Example 8: Y 0.68 Mg 0.22 Ce 0.1 Ni 3.38 Mn 0.35 Zn 0.05

[0069] Compared with Example 1, the component content of the hydrogen storage alloy in Comparative Example 8 was different. The alloy composition of this comparative example was Y 0.68 Mg 0.22 Ce 0.1 Ni 3.38 Mn 0.35 Zn 0.05 。

[0070] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, elemental metals Y, Mg, Ce, Ni, Mn, and Zn were used as raw materials for proportioning, and an as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process was as follows: heating from room temperature to 500 °C at a heating rate of 5 °C / min, then rising to 700 °C at a heating rate of 2 °C / min, and then increasing to 950 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and hydrogen storage alloy Y was obtained. 0.68 Mg 0.22 Ce 0.1 Ni 3.38 Mn 0.35 Zn 0.05 。

[0071] The testing method of Comparative Example 8 was the same as that of Example 1. The results showed that at 25 °C, the hydrogen absorption amount of the alloy was 1.38 wt%, the hydrogen desorption plateau pressure was 0.54 MPa, the effective hydrogen desorption amount was 1.31 wt%, and the slope factor S of the hydrogen desorption plateau f was 0.95. Using the hydrogen desorption plateau pressure at different temperatures and the van’t Hoff formula, the hydrogen desorption enthalpy change of the alloy was calculated to be 27.76 kJ / mol, and by extrapolation, it was found that the hydrogen desorption plateau pressure of the alloy at 120 °C was 8.09 MPa. Structure analysis showed that there were A2B7-type phase, A5B 19 -type phase and AB5-type phase, and the phase contents were 58.01%, 33.54% and 8.45% respectively.

[0072] Comparative Example 9: Y 0.6 Mg 0.25 La 0.15 Ni 3.35 Mn 0.4 Si 0.05

[0073] Compared with Example 1, the component content of the hydrogen storage alloy in Comparative Example 9 was different. The alloy composition of this comparative example was Y 0.6 Mg 0.25 La 0.15 Ni 3.35 Mn 0.4 Si 0.05 。

[0074] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, metallic elements Y, Mg, La, Ni, Mn, and Si were used as raw materials for proportioning, and an as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process was as follows: heating from room temperature to 500 °C at a heating rate of 5 °C / min, then rising to 700 °C at a heating rate of 2 °C / min, and then increasing to 950 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and hydrogen storage alloy Y was obtained. 0.6 Mg 0.25 La 0.15 Ni 3.35 Mn 0.4 Si 0.05 。

[0075] The testing method of Comparative Example 9 was the same as that of Example 1. The results showed that at 25 °C, the hydrogen absorption amount of the alloy was 1.35 wt%, the hydrogen desorption platform pressure was 0.48 MPa, the effective hydrogen desorption amount was 1.29 wt%, and the slope factor S of the hydrogen desorption platform f was 0.91. Using the hydrogen desorption platform pressure at different temperatures, the hydrogen desorption enthalpy change of the alloy was calculated to be 28.74 kJ / mol by using the van’t Hoff formula, and by extrapolation, it was known that the hydrogen desorption platform pressure of the alloy at 120 °C was 7.91 MPa. Structure analysis showed that there were A2B7-type phase, A5B 19 -type phase and AB5-type phase, and the phase contents were 42.13%, 42.61% and 15.26% respectively.

[0076] Comparative Example 10: Y 0.82 Mg 0.15 Ce 0.03 Ni 3.4 Mn 0.3

[0077] Compared with Example 1, the component content of the hydrogen storage alloy in Comparative Example 10 was different. The alloy composition of this comparative example was Y 0.82 Mg 0.15 Ce 0.03 Ni 3.4 Mn 0.3 。

[0078] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, elemental metals Y, Mg, Ce, Ni, and Mn were used as raw materials for proportioning, and an as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process was as follows: heated from room temperature to 500 °C at a heating rate of 5 °C / min, then raised to 700 °C at a heating rate of 2 °C / min, and then increased to 950 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and hydrogen storage alloy Y was obtained. 0.82 Mg 0.15 Ce 0.03 Ni 3.4 Mn 0.3 。

[0079] The testing method of Comparative Example 10 was the same as that of Example 1. The results showed that at 25 °C, the hydrogen absorption amount of the alloy was 1.58 wt%, the hydrogen desorption plateau pressure was 0.27 MPa, the effective hydrogen desorption amount was 1.46 wt%, and the slope factor S of the hydrogen desorption plateau f was 0.86. Using the hydrogen desorption plateau pressure at different temperatures, the hydrogen desorption enthalpy change of the alloy was calculated to be 34.78 kJ / mol by using the van’t Hoff formula, and by extrapolation, it was found that the hydrogen desorption plateau pressure of the alloy was 8.02 MPa at 120 °C. Structure analysis showed that there were A2B7-type phase and A5B 19 type phase, and the phase contents were 81.24% and 18.76% respectively.

[0080] Comparative Example 11: Y 0.65 Mg 0.15 Ce 0.2 Ni 3.4 Mn 0.3

[0081] Compared with Example 1, the component content of the hydrogen storage alloy in Comparative Example 11 was different. The alloy composition of this comparative example was Y 0.65 Mg 0.15 Ce 0.2 Ni 3.4 Mn 0.3 。

[0082] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed components, metal elements Y, Mg, Ce, Ni, and Mn are used as raw materials for proportioning, and the cast alloy is prepared by medium-frequency induction melting method. The cast alloy is wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube is placed in a muffle furnace for annealing. The annealing process is as follows: heat from room temperature to 500°C at a heating rate of 5°C / min, then increase to 700°C at a heating rate of 2°C / min, and then increase to 950°C at a heating rate of 1°C / min. After maintaining this temperature for 6 hours, cool to room temperature with the furnace to obtain hydrogen storage alloy Y. 0.65 Mg 0.15 Ce 0.2 Ni 3.4 Mn 0.3 .

[0083] The test method of Comparative Example 11 is consistent with that of Example 1. The results show that at 25°C, the hydrogen absorption capacity of the alloy is 1.48 wt%, the hydrogen desorption platform pressure is 0.18 MPa, the effective hydrogen desorption capacity is 1.39 wt%, and the hydrogen desorption platform slope factor S is 0.18 MPa. f The dehydrogenation platform pressure at different temperatures was used to calculate the dehydrogenation enthalpy of the alloy to be 38.00 kJ / mol using the van't Hoff formula. Extrapolation showed that the dehydrogenation platform pressure of the alloy at 120°C was 7.32 MPa. Structural analysis showed that the A2B7 phase and A5B 19 type phase, and the phase contents are 74.37% and 25.63% respectively.

[0084] Comparative Example 12: Y 0.83 Mg 0.15 La 0.02 Ni 3.4 Mn 0.3

[0085] Comparative Example 12 Compared with Example 1, the content of the hydrogen storage alloy is different. The alloy composition of this comparative example is Y 0.83 Mg 0.15 La 0.02 Ni 3.4 Mn 0.3 .

[0086] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, elemental metals Y, Mg, La, Ni, and Mn were used as raw materials for proportioning, and an as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process is as follows: Heat from room temperature to 500 °C at a heating rate of 5 °C / min, then increase the temperature to 700 °C at a heating rate of 2 °C / min, and then increase the temperature to 950 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and hydrogen storage alloy Y was obtained. 0.83 Mg 0.15 La 0.02 Ni 3.4 Mn 0.3 。

[0087] The testing method of Comparative Example 12 was the same as that of Example 1. The results showed that at 25 °C, the hydrogen absorption amount of the alloy was 1.59 wt%, the hydrogen desorption platform pressure was 0.24 MPa, the effective hydrogen desorption amount was 1.45 wt%, and the slope factor S of the hydrogen desorption platform f was 0.83. Using the hydrogen desorption platform pressure at different temperatures, the hydrogen desorption enthalpy change of the alloy was calculated to be 35.55 kJ / mol using the van’t Hoff formula, and by extrapolation, it was found that the hydrogen desorption platform pressure of the alloy was 7.68 MPa at 120 °C. Structure analysis showed that there were A2B7-type phase and A5B 19 type phase, and the phase contents were 71.38% and 28.62% respectively.

[0088] Comparative Example 13: Y 0.35 Mg 0.15 La 0.5 Ni 3.4 Mn 0.3

[0089] Compared with Example 1, the component content of the hydrogen storage alloy in Comparative Example 13 was different. The alloy composition of this comparative example was Y 0.35 Mg 0.15 La 0.5 Ni 3.4 Mn 0.3 。

[0090] Preparation of hydrogen storage alloy: According to the atomic ratio of the designed composition, elemental metals Y, Mg, La, Ni, and Mn were used as raw materials for proportioning, and an as-cast alloy was prepared by medium-frequency induction melting. The as-cast alloy was wrapped with tantalum sheets and sealed in a quartz tube filled with argon, and then the quartz tube was placed in a muffle furnace for annealing treatment. The annealing process was as follows: heating from room temperature to 500 °C at a heating rate of 5 °C / min, then rising to 700 °C at a heating rate of 2 °C / min, and then increasing to 1000 °C at a heating rate of 1 °C / min. After maintaining this temperature for 6 hours, it was cooled to room temperature with the furnace, and hydrogen storage alloy Y was obtained. 0.35 Mg 0.15 La 0.5 Ni 3.4 Mn 0.3 。

[0091] The test method of Comparative Example 13 was the same as that of Example 1. The results showed that at 25 °C, the hydrogen absorption amount of the alloy was 1.47 wt%, the hydrogen desorption platform pressure was 0.12 MPa, the effective hydrogen desorption amount was 1.31 wt%, and the slope factor S of the hydrogen desorption platform f was 1.05. Using the hydrogen desorption platform pressure at different temperatures, the hydrogen desorption enthalpy change of the alloy was calculated to be 38.18 kJ / mol using the van’t Hoff formula, and by extrapolation, it was found that the hydrogen desorption platform pressure of the alloy was 4.96 MPa at 120 °C. Structure analysis showed that there were A2B7-type phase and A5B 19 type phases, and the phase contents were 65.35% and 34.65% respectively.

[0092] The compositions and performance test results of Examples 1-3 and Comparative Examples 1-13 are shown in Table 1 below.

[0093] Table 1: Compositions and performance test results of Examples 1-3 and Comparative Examples 1-13

[0094]

[0095]

[0096] Comparing Example 1 with Comparative Examples 1-2, it can be seen that due to the smaller atomic radius of Mg and the fact that the content of Mg affects the volume of the unit cell of the phase, when the content of Mg is low, although it has a higher hydrogen storage capacity, the hydrogen desorption platform pressure is lower, resulting in a low effective hydrogen desorption capacity. Slightly increasing the atomic ratio of Mg can increase the hydrogen desorption platform pressure of the alloy and further increase the effective hydrogen desorption amount while ensuring that the hydrogen absorption amount (hydrogen storage capacity) does not decrease significantly. However, when the content of Mg is further increased, it will cause the volume of the unit cell of the phase to decrease. Although the hydrogen desorption platform pressure is increased, the hydrogen storage capacity will be reduced, thereby reducing the effective hydrogen desorption amount.

[0097] Comparing Example 1 with Comparative Examples 3-4, it can be seen that when the Ni content on the B side is too low, the content of the A2B7-type phase increases, and the unit cell volume of the phase is also larger. Therefore, it has a higher hydrogen storage capacity, but the hydrogen desorption plateau pressure will decrease. However, when the Ni content is too high, the AB5-type phase will appear, resulting in a decrease in the unit cell volume of the phase, thereby leading to a decrease in the hydrogen absorption amount of the alloy.

[0098] Comparing Example 1 with Comparative Examples 5-6, it can be seen that although the Mn element can improve the hydrogen storage capacity of the alloy and optimize the plateau characteristics, when the Mn content is too low, the hydrogen storage capacity of the alloy decreases significantly, and the slope factor increases significantly, and the hydrogen desorption plateau becomes more inclined. When the Mn content is too high, the large atomic radius of Mn will reduce the hydrogen desorption plateau pressure of the alloy. Although the slope factor is reduced, it will lead to a decrease in the effective hydrogen desorption amount.

[0099] Comparing Example 1 with Comparative Example 7, when using Gd to replace La, the content of the A5B 19 type phase in the alloy increases, resulting in a decrease in the hydrogen storage amount of the alloy, and thus a decrease in the effective hydrogen desorption amount.

[0100] Comparing Example 1 with Comparative Examples 8-9, when Zn, Si, etc. are used for replacement on the B side, the AB5-type phase will appear in the alloy, and the prepared alloy is a mixed phase of A2B7-type, A5B 19 type, and AB5-type. Its hydrogen storage capacity is significantly lower than that of the A2B7-type and A5B 19 type mixed phases of the present invention.

[0101] Comparing Example 1 with Comparative Examples 10-13, the atomic radii of Ce and La are larger than that of Y. When Ce or La is used to replace Y on the A side, it will increase the unit cell volume of the phase in the alloy and improve the hydrogen absorption amount of the alloy. However, when the replacement amount is low, the effect is not obvious. When the atomic ratio of Ce or La in the A side increases to a certain proportion, although the unit cell volume of the phase will be larger, the atomic masses of Ce (140.1) and La (138.9) are greater than that of Y (88.91), which will reduce the hydrogen absorption amount of the alloy. Therefore, the hydrogen storage capacities of the alloys in Comparative Example 11 and Comparative Example 13 decrease significantly, the slope factor increases significantly, and the effective hydrogen desorption amount decreases significantly. It should be noted that if the slope factor is too large, in the actual application process, it will lead to the complication of the pressure control of the hydrogen storage system, the instability of the hydrogen release rate, and greatly increase the operation difficulty and cost.

[0102] The hydrogen storage alloy provided by the present invention can exhibit excellent hydrogen storage capacity and hydrogen storage density. Its hydrogen absorption amount ≥ 1.55 wt%, and the effective hydrogen desorption amount ≥ 1.5 wt%, having good application prospects.

[0103] The above embodiments are only used to illustrate the technical solutions of the present invention rather than limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A hydrogen storage alloy, characterized in that, The chemical general formula of the hydrogen storage alloy is: Y 1-a-b Mg a M b Ni x Mn y A z , where M is at least one of La and Ce, A is at least one of Co, Al, and Fe, 0.15 ≤ a ≤ 0.3, 0.05 ≤ b ≤ 0.15, 3.35 ≤ x ≤ 3.5, 0.25 ≤ y ≤ 0.45, and 0 ≤ z ≤ 0.

2.

2. The hydrogen storage alloy according to claim 1, wherein, 0.15 ≤ a ≤ 0.25, 0.1 ≤ b ≤ 0.15, 3.35 ≤ x ≤ 3.4, 0.3 ≤ y ≤ 0.4, 0 ≤ z ≤ 0.

1.

3. The hydrogen storage alloy according to claim 1, characterized in that, The hydrogen absorption amount of the hydrogen storage alloy at room temperature ≥ 1.55 wt%, and the effective hydrogen desorption amount of the hydrogen storage alloy ≥ 1.5 wt%.

4. The hydrogen storage alloy according to claim 1, wherein The structural phases of the hydrogen storage alloy are A2B7 phase and A5B 19 phase.

5. The hydrogen storage alloy according to claim 1, characterized in that, The hydrogen storage alloy is Y 0.75 Mg 0.15 La 0.1 Ni 3.4 Mn 0.3 、Y 0.68 Mg 0.22 Ce 0.1 Ni 3.38 Mn 0.35 Co 0.05 or Y 0.6 Mg 0.25 La 0.15 Ni 3.35 Mn 0.4 Al 0.05 Fe 0.05 .

6. A method for preparing a hydrogen storage alloy according to any one of claims 1-5, characterized in that, It includes the following steps: According to the chemical general formula Y 1-a-b Mg a M b Ni x Mn y A z Weigh and mix the raw materials according to the stoichiometric ratio, and obtain the hydrogen storage alloy through smelting and annealing treatments.

7. The preparation method according to claim 6, wherein, The melting is carried out by medium-frequency induction melting method.

8. The preparation method according to claim 6, characterized in that, The steps of the annealing treatment include: heating from room temperature to 450 - 550 °C at a heating rate of 3 - 7 °C / min, then heating to 650 - 750 °C at a heating rate of 1 - 3 °C / min, then heating to 950 - 1010 °C at a heating rate of 1 - 3 °C / min, holding for 6 - 18 h, and cooling.

9. A hydrogen storage device, characterized in that, It includes the hydrogen storage alloy as described in any one of claims 1 - 5.

10. A hydrogen storage system, characterized in that, It includes the hydrogen storage device as described in claim 9.

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