A non-activated high-capacity magnesium-based hydrogen storage alloy and its preparation method

Abstract

The present invention discloses a preparation method of an activation-free high-capacity magnesium-based hydrogen storage alloy, which relates to the field of magnesium-based hydrogen storage materials and includes the following steps: First, weigh a certain proportion of Mg, Mg-Ni master alloy, and another 1-2 kinds of Mg metal master alloys or alkali metals, and then add the raw materials into an electric resistance furnace to obtain a magnesium-based hydrogen storage alloy through high-temperature melting. Finally, cut, crush, and sieve the magnesium-based hydrogen storage alloy obtained after melting in the air to obtain magnesium-based hydrogen storage alloy powder. The present invention also discloses a magnesium-based hydrogen storage alloy material prepared by the above method. By adding alloying elements such as Al, Zn, Ce, Zr, Mn, Nb, Ti, Ca, K, Na, etc., on the one hand, an antioxidant protective layer can be formed on the surface of the magnesium-based hydrogen storage alloy, thus having a certain effect of resisting air poisoning. On the other hand, the alloying elements refine the Mg grains and the Mg-Ni eutectic structure, shorten the material activation time, and obtain a hydrogen storage material with excellent performance, and the hydrogen storage capacity > 6 wt.%.

Description

Technical Field

[0001] The present invention relates to the field of magnesium-based hydrogen storage materials, and particularly to a non-activated high-capacity magnesium-based hydrogen storage alloy and a preparation method thereof. Background Art

[0002] The energy issue has always been a focus of concern in the development of human society. Fossil fuels such as coal, oil, and natural gas are still our main energy sources, but the combustion of these traditional energy sources produces a large amount of greenhouse gases such as carbon dioxide, as well as toxic chemical substances such as carbon monoxide and sulfur oxides, seriously threatening the environment on which humans depend for survival. In the context of the sustainable development of human society, reducing dependence on fossil fuels and developing and utilizing clean new energy have become increasingly urgent. Among various new energy sources, hydrogen energy has a high combustion calorific value, the utilization product is only water, and it can provide sustainable energy, and will play a crucial role in the future energy structure.

[0003] The development and utilization of hydrogen energy mainly include three aspects: hydrogen production, hydrogen storage and transportation, and hydrogen application. Among them, hydrogen storage and transportation is to store and transport hydrogen from centralized industrial production workshops to scattered hydrogen-using scenarios, which is one of the key technologies for large-scale application of hydrogen energy. Gas-phase hydrogen storage and transportation, liquid-phase hydrogen storage and transportation, and material-based solid-phase hydrogen storage and transportation are currently the three main hydrogen storage and transportation methods. Gas-phase hydrogen storage has problems such as low volumetric energy density, and at the same time, ultra-high-pressure gas also increases people's safety concerns. Liquid-phase hydrogen storage is to freeze and compress hydrogen to ultra-low temperature liquid, and the liquefaction cost is high and the daily loss of liquid hydrogen is inevitable. Solid-phase hydrogen storage has the advantages of high storage density, low cost, safety and stability, and long service life, and is expected to become the new generation of mainstream hydrogen storage and transportation method.

[0004] Magnesium hydride has the advantages of high hydrogen storage capacity, large energy density, and rich resources, and is a very promising solid-phase hydrogen storage material. However, it has thermodynamic stability, slow hydrogen release kinetics, and is easily oxidized in air, which limit its practical application. At present, alloying, nanosizing, and adding catalysts are effective means to improve the comprehensive hydrogen storage performance of magnesium-based hydrogen storage materials. However, the introduction of catalysts or alloy components will inevitably reduce the overall hydrogen storage capacity, and the disadvantage that magnesium-based hydrogen storage materials are easily oxidized is still difficult to solve at present; the nano-magnesium hydride hydrogen storage materials prepared by nanosizing are more active in air and are extremely easy to be poisoned.

[0005] It can be seen that mass-producing a non-activated high-capacity magnesium-based hydrogen storage alloy with anti-air oxidation ability is a problem that must be solved for the commercial application of magnesium-based hydrogen storage materials.

[0006] Therefore, the technical personnel in this field are committed to developing a non-activated high-capacity magnesium-based hydrogen storage alloy and a preparation method thereof. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is the problems of low hydrogen storage capacity, long activation time, easy oxidation and easy poisoning of the magnesium-based hydrogen storage material.

[0008] To achieve the above object, the present invention provides a method for preparing an activation-free high-capacity magnesium-based hydrogen storage alloy, and the method includes the following steps:

[0009] Step 1: Weigh Mg, Mg-Ni master alloy and another 1-2 kinds of Mg master alloys or alkali metals in a certain proportion;

[0010] Step 2: Add the raw materials into a crucible resistance furnace and obtain a magnesium-based hydrogen storage alloy through high-temperature melting;

[0011] Step 3: After melting, cut and crush the magnesium-based hydrogen storage alloy in the air and sieve it to obtain magnesium-based hydrogen storage alloy powder.

[0012] Further, the Mg master alloys in Step 1 are Mg-Ce master alloy and Mg-Zr master alloy.

[0013] Further, the proportion of each metal element in Step 1 is: according to the element mass ratio Mg:Ni:Ce:Zr = 80-95:1-15:1-5:0.5-5.

[0014] Further, the Mg master alloys in Step 1 are Mg-Al master alloy, Mg-Zn master alloy, Mg-Mn master alloy, Mg-Nb master alloy, Mg-Ti master alloy or Mg-Ca master alloy.

[0015] Further, the proportion of each metal element in Step 1 is: according to the element mass ratio Mg:Ni:Al / Zn / Mn / Nb / Ti / Ca = 80-95:1-15:0.5-5.

[0016] Further, the alkali metal in Step 1 is metal Na or metal K.

[0017] Further, the proportion of each metal element in Step 1 is: according to the element mass ratio Mg:Ni:Na / K = 80-95:1-15:0.5-5.

[0018] Further, the high-temperature melting in step 2 is specifically as follows: under a protective atmosphere, the raw materials are added into a crucible. After being fully mixed evenly, they are cooled to room temperature by a rapid cooling method to obtain the magnesium-based hydrogen storage alloy. The protective atmosphere is a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1. The order of adding the raw materials into the crucible is as follows: first, Mg is heated to 750 °C and melted under the protective atmosphere, and then Mg-Ni master alloy and another 1-2 kinds of Mg master alloy or alkali metals are added in sequence. After each addition of a master alloy, a stirring spoon is used to stir up and down for 5-10 min to ensure that different metals are fully mixed evenly. The rapid cooling method is assisted air-cooling, and the cooling rate is 30-50 K / min.

[0019] Further, the particle size of the magnesium-based hydrogen storage alloy powder obtained in step 3 is <200 mesh.

[0020] The present invention also discloses a non-activated high-capacity magnesium-based hydrogen storage alloy prepared by using the above method.

[0021] In a preferred embodiment of the present invention, in order to shorten the diffusion distance of hydrogen in the alloy, the alloy prepared by melting needs to be crushed. The hydrogen storage alloy can be directly cut, crushed and sieved in air to obtain alloy powder with a particle size <200 mesh, which is beneficial to shortening the hydrogen absorption time of the alloy in the subsequent process.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] 1. By controlling the alloy composition, an antioxidant protective layer is formed on the surface of the magnesium-based hydrogen storage alloy, and a magnesium-based hydrogen storage material that can be crushed in air and has a certain resistance to air poisoning is prepared in batches. After the magnesium-based hydrogen storage material is exposed to air, the hydrogen storage capacity will not decay.

[0024] 2. By controlling the alloy synthesis process and alloy composition, the prepared magnesium-based hydrogen storage alloy does not require pre-activation, and the activation time required for the first hydrogen absorption is <30 min. Preferably, elements such as Al, Zn, Ce, Zr, Mn, Nb, Ti, Ca, K, and Na are added to refine the Mg grains and Mg-Ni eutectic structure, shortening the material activation time.

[0025] 3. By preferably adding a small amount of alloy components, a high-capacity magnesium-based hydrogen storage material with excellent performance is prepared, solving the problem that the capacity will be greatly reduced when a catalyst or alloy components are added to the magnesium-based hydrogen storage material. The hydrogen storage capacity of the prepared magnesium-based hydrogen storage alloy is >6 wt%.

[0026] The following will further illustrate the concept, specific structure and technical effects of the present invention with reference to the drawings, so as to fully understand the purpose, features and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the X-ray diffraction pattern (XRD) of the hydrogen storage alloy material prepared in Example 1;

[0028] Figure 2 is the first kinetic hydrogen absorption curve at 350 °C of the hydrogen storage alloy material prepared in Example 1;

[0029] Figure 3 is the hydrogen absorption and desorption curve at 350 °C of the hydrogen storage alloy material prepared in Example 1 (the ab segment is the hydrogen absorption curve and the de segment is the hydrogen desorption curve);

[0030] Figure 4 is the thermodynamic hydrogen absorption and desorption curve at 320 °C of the hydrogen storage alloy material prepared in Example 1 (the ab segment is the hydrogen absorption curve and the de segment is the hydrogen desorption curve);

[0031] Figure 5 is the DSC-TG diagram of the hydrogen storage alloy material prepared in Example 1 at a heating rate of 5 K / min. Detailed implementation manners

[0032] The following introduces multiple preferred embodiments of the present invention with reference to the accompanying drawings of the specification to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0033] In the drawings, components with the same structure are denoted by the same numeral labels, and components with similar structures or functions everywhere are denoted by similar numeral labels. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of some parts in the drawings is appropriately exaggerated.

[0034] In view of the characteristics that the magnesium-based hydrogen storage alloy is easily oxidized, the present invention forms an antioxidant protective layer on the surface of the magnesium-based hydrogen storage alloy by controlling the alloy composition. After the magnesium-based hydrogen storage material is exposed to air, the hydrogen storage capacity will not decay. In addition, the Mg grains prepared by melting are large, the kinetics is slow, and the material is easily poisoned by air, resulting in a long activation time or even inactivation of the material. By controlling the alloy synthesis process and alloy composition, the prepared magnesium-based storage alloy does not require pre-activation, and the activation time required for the first hydrogen absorption < 30 min. The alloy composition, content, and addition method will all affect the comprehensive hydrogen storage performance of the final hydrogen storage material. The present invention prepares a high-performance hydrogen storage material by controlling the alloy composition and content added to the magnesium matrix and optimizing the preparation conditions. The magnesium content is higher than 80 wt%, the nickel content is 1-15 wt%, preferably 1-2 kinds of alloying elements are added in small amounts (0.5-5 wt% Al, Zn, Ce, Zr, Mn, Nb, Ti, Ca, K, Na), and a hydrogen storage material with excellent performance is obtained, and the hydrogen storage capacity > 6 wt%.

[0035] Example 1

[0036] Metals and metal master alloys are used as raw materials, including Mg, Mg-Ni master alloy, Mg-Ce master alloy, and Mg-Zr master alloy. The addition amount of various metals is controlled, and Mg, Mg-Ni master alloy, Mg-Ce master alloy, and Mg-Zr master alloy are added in a ratio of element mass ratio Mg: Ni: Ce: Zr = 89.5: 7.5: 2.5: 0.5. The raw materials are added into a crucible resistance furnace, and magnesium-based hydrogen storage alloy is obtained by high-temperature smelting. The specific steps of smelting are as follows: First, Mg is heated to 750°C and melted under the protection of a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1. Then, Mg-Zr, Mg-Ni, and Mg-Ce intermediate alloys are added in the above element ratios. After adding an alloy each time, stir it up and down with a stirring spoon for about 5 minutes to ensure that the different metals are fully mixed. After the raw materials are fully stirred and mixed, auxiliary air cooling is used to cool to room temperature at a faster rate to prepare Mg-7.5Ni-2.5Ce-0.5Zr hydrogen storage alloy. In order to shorten the diffusion distance of hydrogen in the alloy, the alloy prepared by smelting needs to be crushed. The hydrogen storage alloy can be directly cut, crushed and sieved in the air to obtain an alloy powder with a particle size of <200 mesh, which is conducive to shortening the diffusion distance of hydrogen in the subsequent hydrogen absorption process of the alloy.

[0037] Figure 1 The prepared hydrogen storage alloy powder is mainly composed of magnesium. The added Mg-Ni and Mg-Ce intermediate alloys form fine Mg after smelting. 2 Ni、Mg 12 Ce precipitates are dispersed in the Mg matrix to obtain Mg grains and Mg 2 Ni eutectic structure, the Zr content is too low and is not shown in the XRD spectrum.

[0038] Figure 2 This is the first kinetic hydrogen absorption curve at 350°C. Take 500mg of the prepared hydrogen storage alloy powder and put it into the sample chamber of the hydrogen absorption and desorption tester. Heat it to 350°C under vacuum conditions and keep it warm. Then add 3MPa of hydrogen to the sample chamber, record the change of hydrogen pressure in the equipment over time, and calculate the amount of hydrogen adsorption. The first hydrogen absorption process of the alloy does not require pre-activation and can be completed directly.

[0039] Figure 3 is the thermodynamic hydrogen absorption and desorption curve at 350℃. Take 500mg of the prepared hydrogen storage alloy powder and put it into the sample chamber of the hydrogen absorption and desorption tester. Heat it to 350℃ under vacuum and keep it warm. The hydrogen pressure in the sample chamber is gradually increased by program control, and the saturated hydrogen adsorption amount of the material under different pressures is recorded. Similarly, when tested at 320℃, Figure 4The thermodynamic hydrogen absorption and desorption curves at 320 °C shown. The hydrogen storage capacity of the alloy system > 6 wt%.

[0040] Figure 5 It is a DSC-TG diagram with a heating rate of 5 K / min. The hydrogen storage alloy is fully hydrogenated in a hydrogen absorption and desorption tester, and then the sample is taken out of the sample chamber to obtain a sample in a saturated hydrogenated state. The thermal effect and mass change of the material during the heating process with a heating rate of 5 K / min are obtained through a thermogravimetric-differential scanning calorimeter. The hydrogen storage capacity of the alloy measured by the gravimetric method is consistent with the test result of the volumetric method.

[0041] Example 2

[0042] Using metals and metal master alloys as raw materials, including Mg, Mg-Ni master alloy, Mg-Ce master alloy, and Mg-Zr master alloy. Control the addition amounts of various metals, and add the raw materials in the ratio of the elemental mass ratio Mg:Ni:Ce:Zr = 80:15:2.5:2.5 for Mg, Mg-Ni master alloy, Mg-Ce master alloy, and Mg-Zr master alloy. Add the raw materials into a crucible resistance furnace and obtain a magnesium-based hydrogen storage alloy through high-temperature melting. The specific steps of melting are as follows: First, heat Mg to 750 °C and melt it under the gas protection of a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1. Then, add the Mg-Zr, Mg-Ni, and Mg-Ce master alloys in the above elemental ratio in sequence. After adding each alloy, stir it up and down with a stirring spoon for about 10 min to ensure full mixing between different metals. After fully stirring and mixing all the raw materials evenly, use auxiliary air cooling to cool it to room temperature at a relatively fast rate to prepare a Mg-15Ni-2.5Ce-2.5Zr hydrogen storage alloy. To shorten the diffusion distance of hydrogen in the alloy, it is necessary to crush the alloy prepared by melting. The hydrogen storage alloy can be directly cut, crushed, and sieved in the air to obtain alloy powder with a particle size < 200 mesh. The hydrogen storage capacity of the obtained hydrogen storage material > 6 wt%.

[0043] Example 3

[0044] Using metals and metal master alloys as raw materials, including Mg, Mg-Ni master alloy, Mg-Ce master alloy, and Mg-Zr master alloy. Control the addition amounts of various metals, and add Mg, Mg-Ni master alloy, Mg-Ce master alloy, and Mg-Zr master alloy to the raw materials according to the elemental mass ratio of Mg:Ni:Ce:Zr = 93.5:5:1:0.5. Add the raw materials into a crucible resistance furnace and obtain a magnesium-based hydrogen storage alloy through high-temperature melting. The specific steps of melting are as follows: First, heat Mg to 750 °C and melt it under the protection of a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1. Then, successively add Mg-Zr, Mg-Ni, and Mg-Ce master alloys according to the above elemental ratios. After adding each alloy, stir up and down with a stirring spoon for about 5 minutes to ensure full mixing between different metals. After fully stirring and mixing all the raw materials evenly, use auxiliary air cooling to cool to room temperature at a relatively fast rate to prepare a Mg-5Ni-1Ce-0.5Zr hydrogen storage alloy. To shorten the diffusion distance of hydrogen in the alloy, it is necessary to crush the alloy prepared by melting. The hydrogen storage alloy can be directly cut, crushed, and sieved in the air to obtain alloy powder with a particle size <200 mesh, which can directly absorb hydrogen at 350 °C for the first time, with an initial hydrogen absorption incubation stage <10 minutes and a hydrogen storage capacity >6.5 wt%.

[0045] Example 4

[0046] Using metals and metal master alloys as raw materials, including Mg, Mg-Ni master alloy, and Mg-Al master alloy. Control the addition amounts of various metals, and add Mg, Mg-Ni master alloy, and Mg-Al master alloy to the raw materials according to the elemental mass ratio of Mg:Ni:Al = 85:10:5. Add the raw materials into a crucible resistance furnace and obtain a magnesium-based hydrogen storage alloy through high-temperature melting. The specific steps of melting are as follows: First, heat Mg to 750 °C and melt it under the protection of a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1. Then, successively add Mg-Ni and Mg-Al master alloys according to the above elemental ratios. After adding each alloy, stir up and down with a stirring spoon for about 5 minutes to ensure full mixing between different metals. After fully stirring and mixing all the raw materials evenly, use auxiliary air cooling to cool to room temperature at a relatively fast rate to prepare a Mg-10Ni-5Al hydrogen storage alloy. To shorten the diffusion distance of hydrogen in the alloy, it is necessary to crush the alloy prepared by melting. The hydrogen storage alloy can be directly cut, crushed, and sieved in the air to obtain alloy powder with a particle size <200 mesh.

[0047] Example 5

[0048] Using metals and metal master alloys as raw materials, including Mg, Mg-Ni master alloy, and Mg-Zn master alloy. Control the addition amounts of various metals. The Mg, Mg-Ni master alloy, and Mg-Zn master alloy are added to the raw materials in a ratio of element mass ratio Mg:Ni:Zn = 80:15:5. Add the raw materials into a crucible resistance furnace and obtain a magnesium-based hydrogen storage alloy through high-temperature melting. The specific steps of melting are as follows: First, heat Mg to 750 °C and melt it under the protection of a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1. Then, add the Mg-Ni and Mg-Zn master alloys in the above element ratio in sequence. After adding each alloy, stir it up and down with a stirring spoon for about 5 minutes to ensure sufficient mixing between different metals. After the raw materials are fully stirred and mixed evenly, use auxiliary air cooling to cool to room temperature at a relatively fast rate to prepare the Mg-15Ni-5Zn hydrogen storage alloy. To shorten the diffusion distance of hydrogen in the alloy, it is necessary to crush the alloy prepared by melting. The hydrogen storage alloy can be directly cut, crushed, and sieved in the air to obtain alloy powder with a particle size <200 mesh. The alloy material does not require the protection of inert gas during daily storage.

[0049] Example 6

[0050] Using metals and metal master alloys as raw materials, including Mg, Mg-Ni master alloy, and Mg-Mn master alloy. Control the addition amounts of various metals. The Mg, Mg-Ni master alloy, and Mg-Mn master alloy are added to the raw materials in a ratio of element mass ratio Mg:Ni:Mn = 95:2.5:2.5. Add the raw materials into a crucible resistance furnace and obtain a magnesium-based hydrogen storage alloy through high-temperature melting. The specific steps of melting are as follows: First, heat Mg to 750 °C and melt it under the protection of a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1. Then, add the Mg-Ni and Mg-Mn master alloys in the above element ratio in sequence. After adding each alloy, stir it up and down with a stirring spoon for about 5 minutes to ensure sufficient mixing between different metals. After the raw materials are fully stirred and mixed evenly, use auxiliary air cooling to cool to room temperature at a relatively fast rate to prepare the Mg-2.5Ni-2.5Mn hydrogen storage alloy. To shorten the diffusion distance of hydrogen in the alloy, it is necessary to crush the alloy prepared by melting. The hydrogen storage alloy can be directly cut, crushed, and sieved in the air to obtain alloy powder.

[0051] Example 7

[0052] Using metals and master alloys as raw materials, including Mg, Mg-Ni master alloy, and Mg-Ti master alloy. Control the addition amounts of various metals. Mg, Mg-Ni master alloy, and Mg-Ti master alloy are added to the raw materials in the ratio of element mass ratio Mg:Ni:Ti = 89.5:7.5:3. Add the raw materials into a crucible resistance furnace and obtain a magnesium-based hydrogen storage alloy through high-temperature melting. The specific steps of melting are as follows: First, under the protection of a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1, heat Mg to 750 °C and melt it. Then, successively add Mg-Ni and Mg-Ti master alloys according to the above element ratio. After adding each alloy, stir up and down with a stirring spoon for about 5 minutes to ensure full mixing between different metals. After fully stirring and mixing all the raw materials evenly, use auxiliary air cooling to cool to room temperature at a relatively fast rate to prepare the Mg-7.5Ni-3Ti hydrogen storage alloy. To shorten the diffusion distance of hydrogen in the alloy, it is necessary to crush the alloy prepared by melting. The hydrogen storage alloy can be directly cut, crushed, and sieved in the air to obtain alloy powder with a particle size <200 mesh. The hydrogen absorption activation time of the alloy is <3 minutes under the conditions of 350 °C and 3 MPa, and the hydrogen storage capacity >6.2 wt%.

[0053] Example 8

[0054] Using metals and master alloys as raw materials, including Mg, Mg-Ni master alloy, and Mg-Ca master alloy. Control the addition amounts of various metals. Mg, Mg-Ni master alloy, and Mg-Ca master alloy are added to the raw materials in the ratio of element mass ratio Mg:Ni:Ca = 90:5:5. Add the raw materials into a crucible resistance furnace and obtain a magnesium-based hydrogen storage alloy through high-temperature melting. The specific steps of melting are as follows: First, under the protection of a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1, heat Mg to 750 °C and melt it. Then, successively add Mg-Ni and Mg-Ca master alloys according to the above element ratio. After adding each alloy, stir up and down with a stirring spoon for about 5 minutes to ensure full mixing between different metals. After fully stirring and mixing all the raw materials evenly, use auxiliary air cooling to cool to room temperature at a relatively fast rate to prepare the Mg-5Ni-5Ca hydrogen storage alloy. Crush the alloy prepared by melting, and then directly cut, crush, and sieve it in the air to obtain alloy powder with a particle size <200 mesh. The hydrogen storage capacity of the alloy is >6 wt% under the conditions of 350 °C and 3 MPa.

[0055] Example 9

[0056] Using metals and metal master alloys as raw materials, including Mg, Mg-Ni master alloy, and metal K. Control the addition amounts of various metals, and add Mg, Mg-Ni master alloy, and metal K to the raw materials in the elemental mass ratio of Mg:Ni:K = 87.5:7.5:5. Add the raw materials into a crucible resistance furnace and obtain a magnesium-based hydrogen storage alloy through high-temperature melting. The specific steps of melting are as follows: First, heat Mg to 750 °C and melt it under the protection of a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1. Then, add Mg-Ni and metal K in the above elemental ratio in sequence. After adding each alloy, stir it up and down with a stirring spoon for about 5 minutes to ensure sufficient mixing between different metals. After fully stirring and mixing all the raw materials evenly, use auxiliary air cooling to cool it to room temperature at a relatively fast rate to prepare the Mg-7.5Ni-5K hydrogen storage alloy. To shorten the diffusion distance of hydrogen in the alloy, it is necessary to crush the alloy prepared by melting. The hydrogen storage alloy can be directly cut, crushed, and sieved in the air to obtain alloy powder with a particle size <200 mesh. The alloy absorbs hydrogen under the conditions of 350 °C and 3 MPa, and the hydrogen storage capacity >6 wt%.

[0057] Example 10

[0058] Using metals and metal master alloys as raw materials, including Mg, Mg-Ni master alloy, and metal Na. Control the addition amounts of various metals, and add Mg, Mg-Ni master alloy, and metal Na to the raw materials in the elemental mass ratio of Mg:Ni:Na = 85:10:5. Add the raw materials into a crucible resistance furnace and obtain a magnesium-based hydrogen storage alloy through high-temperature melting. The specific steps of melting are as follows: First, heat Mg to 750 °C and melt it under the protection of a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1. Then, add Mg-Ni and metal Na in the above elemental ratio in sequence. After adding each alloy, stir it up and down with a stirring spoon for about 5 minutes to ensure sufficient mixing between different metals. After fully stirring and mixing all the raw materials evenly, use auxiliary air cooling to cool it to room temperature at a relatively fast rate to prepare the Mg-10Ni-5Na hydrogen storage alloy. To shorten the diffusion distance of hydrogen in the alloy, it is necessary to crush the alloy prepared by melting. The hydrogen storage alloy can be directly cut, crushed, and sieved in the air to obtain alloy powder with a particle size <200 mesh. The alloy absorbs hydrogen under the conditions of 350 °C and 3 MPa, and the hydrogen storage capacity >6 wt%.

[0059] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations according to the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. Preparation method of non-activated high-capacity magnesium-based hydrogen storage alloy, characterized in that, the method comprises the following steps: Step 1: Weigh Mg, Mg-Ni master alloy and Mg metal master alloy or alkali metal in a certain proportion; the Mg metal master alloy is Mg-Ce master alloy and Mg-Zr master alloy, according to the element mass ratio Mg:Ni:Ce:Zr = 80-95:1-15:1-5:0.5-5; or the Mg metal master alloy is Mg-Al master alloy, Mg-Zn master alloy, Mg-Mn master alloy, Mg-Nb master alloy, Mg-Ti master alloy or Mg-Ca master alloy, according to the element mass ratio Mg:Ni:Al / Zn / Mn / Nb / Ti / Ca = 80-95:1-15:0.5-5; or the alkali metal is metallic Na or metallic K, according to the element mass ratio Mg:Ni:Na / K = 80-95:1-15:0.5-5; the alloy components form an antioxidant protective layer on the surface of the magnesium-based hydrogen storage alloy, and the non-activated high-capacity magnesium-based hydrogen storage alloy is a magnesium-based hydrogen storage material with a certain resistance to air poisoning. After the magnesium-based hydrogen storage material is exposed to air, the hydrogen storage capacity will not decay; Step 2: Add the raw materials into a crucible resistance furnace and obtain the magnesium-based hydrogen storage alloy through high-temperature melting; Step 3: After melting, cut and crush the magnesium-based hydrogen storage alloy in air, and screen it to obtain magnesium-based hydrogen storage alloy powder. The particle size of the obtained magnesium-based hydrogen storage alloy powder is <200 mesh, which is beneficial to shortening the hydrogen absorption time of the alloy in the subsequent process.

2. The preparation method of the non-activated high-capacity magnesium-based hydrogen storage alloy according to claim 1, characterized in that, the high-temperature melting in step 2 is specifically: under a protective atmosphere, add the raw materials into a crucible, fully mix them evenly, and then cool them to room temperature by a rapid cooling method to obtain the magnesium-based hydrogen storage alloy; the protective atmosphere is a mixed gas of carbon dioxide and sulfur hexafluoride with a volume ratio of 99:1; the order of adding the raw materials into the crucible is: first heat Mg to 750 °C and melt it under the protective atmosphere, and then add Mg-Ni master alloy and another 1-2 kinds of Mg master alloys or alkali metals in turn. After adding one master alloy each time, use a stirring spoon to stir up and down for 5-10 min to ensure full mixing of different metals. The rapid cooling method is assisted air-cooling, and the cooling rate is 30-50 K / min.

3. A non-activated high-capacity magnesium-based hydrogen storage alloy, characterized in that, the magnesium-based hydrogen storage alloy is prepared by using the preparation method described in any one of claims 1-2.

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