A magnesium-based alloy for cyclic hydrogen storage and a preparation method thereof

Abstract

The present invention discloses a magnesium-based alloy for cyclic hydrogen storage and release and a preparation method thereof. The magnesium-based alloy comprises an Mg-Ni-La alloy and a metal film. The Mg-Ni-La alloy is composed of Mg, Ni, and La elements. The content of Ni is 8.0-14.0 wt%, and the content of La is 0.1-3.0 wt%. The Mg-Ni-La alloy is a tablet formed by agglomeration of particles; the metal film coats the tablet, and the mass ratio of the metal film to the Mg-Ni-La alloy is (0.001-0.002):1. The porous metal copper film of the Mg-Ni-La alloy of the present invention has a uniform pore distribution and presents an irregular shape, which can improve the hydrogen storage and release rate, improve the hydrogen storage and release cycle performance, and reduce the hydrogen storage and release temperature and the rate of particle pulverization. It has the characteristics of low cost and simple processing technology, and is more conducive to the popularization and application of magnesium-nickel-based hydrogen storage alloys.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen storage materials, and particularly relates to a magnesium-based alloy for cyclic hydrogen storage and release and a preparation method thereof. Background Art

[0002] As one of the important technologies in the energy storage field, hydrogen storage is a key node that must be overcome in the application of hydrogen energy. The maturity of hydrogen storage technology will not only change the current energy structure but also drive the rise of a batch of new materials.

[0003] Currently, there are mainly two types of hydrogen storage technologies: the first is the traditional hydrogen storage method, including high-pressure gaseous hydrogen storage and low-temperature liquid hydrogen storage; the second is hydrogen storage using new hydrogen storage materials, including hydrogen storage alloys, carbonaceous materials, organic liquid hydrides, etc. Traditional high-pressure gas cylinders or liquid and solid hydrogen storage are neither economical nor safe, and the use of hydrogen storage materials can solve the above problems.

[0004] A hydrogen storage material is a material that can reversibly absorb and release a large amount of hydrogen at appropriate temperatures and pressures and has a sufficient number of reversible cycles. The important function of a hydrogen storage material is to act as an energy carrier or a hydrogen carrier, responsible for energy storage, conversion, and transportation, and cooperate with hydrogen to form various different energy carrier systems. For example, by utilizing the reversible reaction heat of the hydrogen storage material, a heat-carrying system can be formed to complete the tasks of heat energy storage, conversion, and transportation. When converting electrical energy and chemical energy into each other, by utilizing the characteristic of the hydrogen storage material to store chemical energy, an electric-carrying system can be formed to store and convert electrical energy. Hydrogen storage materials can also form a hydrogen-carrying system to realize the storage, transportation, separation, purification of hydrogen, and the recovery of hydrogen isotopes. The energy carrier or hydrogen carrier is a more essential reflection of such materials.

[0005] According to the research on the physical and chemical properties of hydrogen, if a hydrogen storage material is to have practical value, in addition to meeting the basic requirements such as safe storage, convenient transportation, and reasonable cost, certain requirements are also imposed on the hydrogen storage performance of the material, the temperature and pressure required for storage, and the kinetic rate of hydrogen charging / discharging. Generally, a hydrogen storage material should meet the following conditions: ① easy to activate, with a high hydrogen storage content per unit mass and unit volume; ② having a high degree of reaction reversibility and being able to occur at normal temperature and pressure; ③ having a good cycle life and still maintaining stable performance even after a sufficient number of cycles; ④ having a small equilibrium hydrogen pressure difference during the process of hydrogen absorption and dissociation, that is, a small hysteresis effect; ⑤ having excellent anti-poisoning performance, being stable in air, having good safety, and not being easily poisoned by impurity gases such as N2, O2, and H2S; ⑥ when designing and producing, attention should also be paid to making it as inexpensive, non-polluting to the environment, simple in manufacturing process, and easy to manufacture as possible.

[0006] Magnesium-based hydrogen storage materials are medium-temperature hydrogen storage materials with high safety, easy storage and transportation, and have become a hot topic in current research and development. For example, Patent CN114507798A discloses a magnesium-based hydrogen storage alloy block and its preparation method. Magnesium blocks, magnesium-nickel master alloy, and magnesium-rare earth master alloy are melted and cast according to the mass ratio of magnesium element, nickel element, and rare earth element of 50-90:10-20:1-10 to obtain an alloy ingot. Subsequently, the alloy ingot is hot extruded into an alloy bar and processed into an alloy electrode. Then, the alloy electrode is atomized to produce magnesium-nickel-rare earth hydrogen storage alloy powder, and the magnesium-nickel-rare earth hydrogen storage alloy powder is pressed into shape. The magnesium-based hydrogen storage alloy block prepared in this way can achieve a high hydrogen absorption amount in a short time and at a low pressure, and can be recycled up to 1500-2000 times.

[0007] However, the US Department of Energy's minimum hydrogen storage amount standard for hydrogen storage materials for practical application in vehicle power sources is that the hydrogen storage mass is not less than 5.5 wt% and the volume density is not less than 40 kg / L. The maximum hydrogen absorption amount of the magnesium-based hydrogen storage materials in the above related prior art still cannot reach the minimum hydrogen storage mass standard.

[0008] Therefore, exploring materials that can adsorb and release hydrogen quickly and in large quantities to achieve effective hydrogen storage is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0009] Aiming at the defects existing in the above-mentioned prior art, the present invention provides a magnesium-based alloy for cyclic hydrogen storage and release and its preparation method. The magnesium-based alloy includes a Mg-Ni-La alloy and a metal film. Trace amounts of Ni element and La element are added. At the same time, the alloy melt is sprayed into spherical powder by an atomization method, and the powder is compressed into tablets within a predetermined compactness numerical range, and heat treatment and surface coating treatment are carried out. The magnesium-based alloy of the present invention improves the hydrogen storage and release speed of the alloy material, reduces the hydrogen storage and release temperature, and improves the hydrogen storage and release cycle performance compared with the prior art. At the same time, it has the characteristics of low cost and simple processing technology, which is more conducive to the popularization and application of magnesium-based hydrogen storage alloys.

[0010] In the first aspect, the present invention provides a magnesium-based alloy for cyclic hydrogen storage and release. The magnesium-based alloy includes a Mg-Ni-La alloy and a metal film. The Mg-Ni-La alloy is composed of Mg, Ni, and La elements. The content of Ni is 8.0-14.0 wt%, and the content of La is 0.1-3.0 wt%. The Mg-Ni-La alloy is a tablet formed by the aggregation of particles;

[0011] The metal film coats the tablet. The metal film has a porous structure. The component of the metal film is a conductive metal element. The mass ratio of the metal film to the Mg-Ni-La alloy is (0.001-0.002):1.

[0012] The surface of the tablet is coated with a metal film, which can improve the electrical and thermal conductivity of the magnesium-based alloy surface. As a reaction bed during the hydrogen storage and release process, it can reach a uniform temperature field in a shorter time, improving the hydrogen storage and release efficiency. Adding La and Ni elements to the Mg-based alloy to form the Mg-Ni-La alloy shows a synergistic catalytic effect in hydrogen storage and release. Specifically, the addition of Ni elements can not only effectively bond and dissociate with hydrogen, but also the Mg2Ni phase in the Mg-Ni-La alloy can undertake part of the hydrogen storage capacity. After saturated hydrogen absorption, LaH with very high thermal stability and difficult dissociation is generated. 3.05 phase, jointly playing a catalytic role in the hydrogen absorption exothermic and hydrogen release endothermic processes of the Mg-Ni-La alloy. The magnesium-based alloy of the present invention finally improves the hydrogen storage and release speed, reduces the temperature of hydrogen storage and release, improves the hydrogen storage and release cycle performance, and at the same time reduces the speed of particle pulverization.

[0013] Furthermore, the content of Ni is 8.0 - 9.0 wt%, and the content of La is 1.5 - 3.0 wt%. As a more preferred scheme, the range of La content is 1.5 - 3.0 wt%. Trace amounts of La will segregate towards the crystal interior during the preparation of the Mg-Ni-La alloy, making the Mg-Ni-La alloy more homogeneous and improving the hydrogen storage and release cycle stability.

[0014] Adding La, La can form LaMg 12 and La2Mg 17 phases. La and H can form LaH3, and La and Ni can form LaNi5. These binary compounds can all promote the hydrogen absorption and release performance of the magnesium-based alloy. Especially the LaNi5 phase is itself a commonly used solid hydrogen storage material, and the hydrogen release temperature is low (<100 °C).

[0015] Within a certain range, the more the above-mentioned second phases, the easier the hydrogen diffusion, and the more beneficial to the hydrogen absorption and release kinetics and thermodynamics of the material. However, the LaH3 phase is difficult to dissociate. Once formed, it exists in the material like a catalyst, only promoting hydrogen absorption and release but no longer participating in hydrogen absorption and release. If La is too much (exceeding 3 wt%), on the one hand, because the atomic weight of La is large, the hydrogen storage density of the material decreases. On the other hand, the proportion of LaH3 will also increase, further affecting the hydrogen storage density of the material.

[0016] Furthermore, the shape of the particles of the tablet is spherical, the compactness of the tablet is 50% - 70%, and the particle size of the particles is 20 - 150 μm.

[0017] If the compactness of the tablet is too small, that is, the porosity is very large and the particles are very loose, during the hydrogen storage and release process, the particles are easily pulverized due to volume changes. If the compactness of the tablet is too large, that is, the porosity is very small, then hydrogen is not easy to diffuse inside the particles, affecting the speed and efficiency of hydrogen storage and release.

[0018] Furthermore, the thickness of the metal film is 30 - 50 μm, and the pore diameter of the metal film is 0.5 - 2 μm. The surface state of the hydrogen storage material affects the kinetic properties. In the solid-gas reaction, the surface of the hydrogen storage material has a catalytic effect. The gas dissociates into hydrogen atoms on the material surface, and the hydrogen atoms diffuse into the material interior and are occluded in the metal atom interstices; when the system is heated, the hydrogen is released again. By repeatedly absorbing / releasing hydrogen, the volume of the material expands and contracts repeatedly, ultimately leading to pulverization. At this time, the thermal conductivity of the material decreases, and the diffusion of the reaction heat becomes the rate-controlling step of the reaction. Therefore, the surface thermal conductivity of the hydrogen storage material is very important.

[0019] In the magnesium-based alloy of the present invention, a metal film with a porous structure is coated on the surface to improve the surface electrical conductivity and thermal conductivity, and to enhance the hydrogen storage and release efficiency of the magnesium-based alloy; at the same time, as a barrier layer, it protects the magnesium-based alloy, prevents the pulverization and oxidation of the magnesium-based alloy, and improves the cycle life.

[0020] Furthermore, before hydrogen storage, the Mg-Ni-La alloy is a multiphase structure composed of LaMg 12 , Mg2Ni, La2Mg 17 and Mg. After hydrogen storage, the Mg-Ni-La alloy is a multiphase structure composed of Mg2NiH4, MgH2 and LaH 3.05 .

[0021] Before hydrogen storage, grain boundaries or lamellar structures are formed between the multiphase structures of the Mg-Ni-La alloy, which can provide channels for the hydrogen absorption sites and the diffusion of hydrogen atoms in the Mg-Ni-La alloy. For example, the eutectic structure composed of Mg-Mg2Ni presents a lamellar structure, and this lamellar eutectic structure provides an effective channel for the diffusion of hydrogen atoms during the hydrogen absorption and release process of the alloy. Therefore, the multiphase structure in the Mg-Ni-La alloy improves the kinetic properties of the hydrogen absorption exothermic and hydrogen release endothermic processes. After hydrogen absorption, the LaMg 12 and La2Mg 17 phases before hydrogen absorption are completely transformed into LaH 3.05 and MgH2 phases.

[0022] In a second aspect, the present invention also provides a preparation method for a magnesium-based alloy used for cyclic hydrogen storage and release, to prepare the magnesium-based alloy used for cyclic hydrogen storage and release as described above, which specifically includes the following steps:

[0023] 1) According to the contents of Mg, Ni and La elements, perform melting and blending to obtain a Mg-Ni-La alloy melt;

[0024] 2) Atomize the Mg-Ni-La alloy melt to form Mg-Ni-La alloy powder;

[0025] 3) Under argon protection, press the Mg-Ni-La alloy powder into tablets;

[0026] 4) The tablets are annealed under the conditions of standing at 300 - 310 °C for 2 - 5 h and then cooling with the furnace.

[0027] 5) A metal film is coated on the surface of the tablets after step 4) to obtain the magnesium-based alloy for cyclic hydrogen storage and release.

[0028] The preparation method of the magnesium-based alloy provided by the present invention reduces the preparation cost, has a simple processing technology, and is more conducive to the popularization and application of the magnesium-based alloy. Among them, the annealing treatment of the tablets in step 4) is used to improve the hydrogen storage and release performance of the Mg-Ni-La alloy. After the annealing treatment, the lattice defects and lattice stress of the Mg-Ni-La alloy are significantly reduced, Ni segregates to the grain boundary, improving the "hydrogen pump" ability of the second phase Mg2Ni in the Mg-Ni-La alloy, and La segregates into the grains, homogenizing the alloy, which has a significant effect on improving the cyclic stability of the material; in addition, the heat treatment can reduce the hydrogen storage and release plateau pressure of the Mg-Ni-La alloy, making the plateau of its PCT curve flatter; moreover, the annealing treatment helps to adjust the gas-solid reversible hydrogen release amount of the Mg-Ni-La alloy.

[0029] Further, step 1) specifically includes the following steps:

[0030] 1.1) Weigh the Mg, Ni, and La elements and preheat them at 180 - 220 °C respectively.

[0031] 1.2) Under a protective atmosphere, the preheated Mg element is melted by multiple additions to form a Mg melt.

[0032] 1.3) After heating the Mg melt to 700 - 740 °C, add the preheated Ni and La elements to obtain an initial mixture.

[0033] 1.4) After the initial mixture is completely melted, stir it, clean the impurities on the surface of the initial mixture, and stand for 10 - 30 min to obtain the Mg-Ni-La alloy melt.

[0034] The pure magnesium, pure nickel, and pure lanthanum are preheated respectively. The preheated pure magnesium is melted in a protective atmosphere, and the addition method of pure magnesium is multiple additions to prevent the segregation of Ni.

[0035] Further, the protective atmosphere is an argon environment, and the masses of the weighed Mg and La elements are 1.05 - 1.1 times the content ratio. During the smelting process, argon is used for slightly positive pressure protection. Magnesium and lanthanum will volatilize during the smelting process, and generally, the ingredients are in a ratio of 1.05 - 1.1 times.

[0036] Further, the atomization of the Mg-Ni-La alloy melt is carried out using an atomization device, which includes an alloy liquid storage bin, a powder making bin, and an argon gas cylinder. The argon gas cylinder provides an inert protection atmosphere for the alloy liquid storage bin and the powder making bin. The bottom of the alloy liquid storage bin is a turntable, and the turntable is provided with a plurality of nozzles that penetrate through the alloy liquid storage bin and the powder making bin;

[0037] Among them, step 2) specifically includes the following steps:

[0038] 2.1) Inject the Mg-Ni-La alloy melt into the alloy liquid storage bin. The temperature in the alloy liquid storage bin is 800-900 °C, and argon gas is filled. The pressure in the alloy liquid storage bin is 0.15-0.3 MPa;

[0039] 2.2) The Mg-Ni-La alloy melt enters the powder making bin through the nozzles of the rotating turntable and is atomized into fine droplets. The argon gas environment in the powder making bin is 1-5 kPa, the rotation speed of the nozzles is 1400-1600 r / min, and the diameter of the nozzles is 5-10 mm;

[0040] 2.3) The fine droplets solidify into Mg-Ni-La alloy powder with a particle size of 20-150 μm in the powder making bin.

[0041] The Mg-Ni-La alloy melt is directly transported to the atomization device, and the liquid sprays out at the outlet of the high-speed rotating nozzles and turns into powder when cooled. Compared with the plasma rotating electrode powder making commonly used in the prior art, there is no need to pour the liquid into an alloy ingot, nor to hot extrude it into an electrode, and then the electrode needs to be heated and melted, which will inevitably increase energy consumption and time. The atomization process of the present invention is simpler and more efficient.

[0042] Further, the component of the metal film is Cu. Among them, step 5) specifically includes the following steps:

[0043] 5.1) Prepare a CuO coating solution with a concentration of 40-90 g / L;

[0044] 5.2) Add the tablets after step 4) and stir;

[0045] 5.3) Take out after stirring for 8-12 min to obtain the initial hydrogen storage alloy with a uniformly coated CuO film;

[0046] 5.4) Under the condition of 180-220 °C, introduce hydrogen to reduce the CuO film and precipitate oxygen to form a hydrogen storage magnesium-based alloy with a metal film having a porous structure.

[0047] Further, step 5.1) specifically includes:

[0048] Add Cu(NO3)2·3H2O to deionized water, heat to 90-120 °C and stir;

[0049] Add NH4HCO3 with a concentration of 2.5 - 3.5 g / L in multiple additions. After the addition is completed, stir at a constant temperature to obtain a CuO coating solution with a concentration of 40 - 90 g / L.

[0050] Coat a copper film on the tablet surface to increase the thermal conductivity of the tablet. During the hydrogen storage and release process, the reaction bed can reach a uniform temperature field in a shorter time. At the same time, the copper film can act as a barrier layer to protect the Mg-Ni-La alloy, prevent the pulverization and oxidation of the Mg-Ni-La alloy, improve the cycle life of the Mg-Ni-La alloy, and the obtained magnesium-based alloy can be promoted and applied as a material for cyclic hydrogen charging and discharging.

[0051] A magnesium-based alloy for cyclic hydrogen storage and release and its preparation method provided by the present invention have at least the following beneficial effects:

[0052] (1) The magnesium-based alloy prepared by the present invention has strong hydrogen storage performance, improves the hydrogen charging and discharging speed and the hydrogen charging and discharging cycle performance, and reduces the hydrogen charging and discharging temperature and the speed of particle pulverization.

[0053] (2) The Mg-Ni-La alloy in the magnesium-based alloy of the present invention is composed of Mg, Ni, and La elements, and shows a synergistic catalytic effect in hydrogen storage and release. Compared with the existing preparation methods, it is not necessary to pour the liquid into an alloy ingot, nor to hot extrude it into an electrode, and it is even less necessary to heat and melt the electrode, which increases energy consumption and time. Therefore, it has the characteristics of low cost and simple processing technology, and is more conducive to the popularization and application of magnesium-based alloys.

[0054] (3) Coating a metal film (such as a copper film) improves the electrical conductivity and thermal conductivity of the magnesium-based alloy, can reach a uniform temperature field in a shorter time, and improves the hydrogen charging and discharging efficiency of the magnesium-based alloy; at the same time, it prevents the pulverization and oxidation of the Mg-Ni-La alloy and improves the cycle life of the magnesium-based alloy. Description of the Drawings

[0055] Figure 1 It is a schematic structural diagram of the atomization device for the alloy melt in the present invention;

[0056] Figure 2 It is a TG-DSC curve graph of the magnesium-based alloy of Example 1 provided by the present invention;

[0057] Figure 3 It is a hydrogen storage capacity curve graph of the magnesium-based alloy of Example 1 provided by the present invention after 100 cycles of hydrogen charging and discharging;

[0058] Figure 4 It is a hydrogen charging curve graph of the magnesium-based alloy of Example 1 provided by the present invention;

[0059] Figure 5 It is a hydrogen release curve graph of the magnesium-based alloy of Example 1 provided by the present invention. Detailed implementation manners

[0060] In order to better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to the accompanying drawings of the specification and specific implementation manners. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0061] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Plural" generally includes at least two.

[0062] It should also be noted that the term "comprises", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a commodity or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such commodity or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the commodity or device comprising said element.

[0063] The performance of the hydrogen storage material should consider both the overall properties and the surface properties. For example, the hydrogen storage capacity, reaction generation amount, etc. are the manifestations of the overall properties, and the overall properties are determined by the composition components, crystal structure, etc. of the material. Activation, passivation, corrosion and oxidation in the electrolyte, electrocatalytic activity, high-rate discharge capacity, and cycle life, etc. belong to the surface properties, and the surface properties are determined by the surface characteristics of the material, and the surface characteristics can be optimized and improved through surface treatment technologies.

[0064] The present invention provides a magnesium-based alloy for cyclic hydrogen storage and release. The magnesium-based alloy includes a Mg-Ni-La alloy and a metal film. The Mg-Ni-La alloy is composed of Mg, Ni, and La elements. The content of Ni is 8.0 - 14.0 wt%, and the content of La is 0.1 - 3.0 wt%, and the rest is Mg. Preferably, the content of Ni is 8.0 - 9.0 wt%, and the content of La is 1.5 - 3.0 wt%. The Mg-Ni-La alloy is a tablet formed by aggregation of particles. The shape of the particles is spherical. The compactness of the tablet is 50% - 70%, and the particle size is 20 - 150 μm;

[0065] The tablet is coated with a metal film having a porous structure. The metal film is composed of conductive metal elements. The mass ratio of the conductive metal elements to the Mg-Ni-La alloy is (0.001-0.002):1. The thickness of the metal film is 30-50 μm. The pores in the porous structure are evenly distributed and present an irregular shape. The pore size of the metal film is 0.5-2 μm.

[0066] The Mg-Ni-La alloy in the magnesium-based alloy of the present invention is composed of Mg, Ni and La elements, and exhibits a synergistic catalytic effect in hydrogen storage and release.

[0067] The hydrogen absorption of Mg-Ni-La alloy is an exothermic reaction, while the hydrogen release is an endothermic reaction, and the heat is very large, about 75kJ / mol. During the hydrogen absorption process, the released heat needs to be discharged in time to facilitate the hydrogen absorption performance, especially the hydrogen absorption speed; during the hydrogen release process, the external heat needs to be transferred to the Mg-Ni-La alloy in time so that the Mg-Ni-La alloy can release hydrogen faster. After hydrogen storage, the thermal conductivity of the magnesium hydride phase structure is poor, which brings great difficulties to the transfer of heat. The thermal conductivity of the Mg-Ni-La alloy can be improved by plating a metal film, which can increase the rate of hydrogen absorption and release. At the same time, the metal film can also serve as a barrier layer to protect the Mg-Ni-La alloy, prevent the pulverization and oxidation of the Mg-Ni-La alloy, and improve the cycle life of the alloy.

[0068] The present invention also provides a method for preparing a magnesium-based alloy for cyclic storage and release of hydrogen, comprising the following steps:

[0069] 1) performing melting matching according to the contents of Mg, Ni and La elements to obtain a Mg-Ni-La alloy melt;

[0070] 2) atomizing the Mg-Ni-La alloy melt to form Mg-Ni-La alloy powder;

[0071] 3) Under argon protection, the Mg-Ni-La alloy powder is pressed into tablets;

[0072] 4) The tablets are annealed under the following conditions: standing at 300-310°C for 2-5 hours, and then cooled in the furnace;

[0073] 5) After step 4), the surface of the tablet is coated with a metal film to obtain a magnesium-based alloy for cyclic storage and release of hydrogen.

[0074] Wherein, step 1) specifically comprises the following steps:

[0075] 1.1) Weigh Mg, Ni and La, the weight of Mg and La being 1.05 to 1.1 times of the specific gravity, and preheat them at 180 to 220°C respectively;

[0076] 1.2) Under an argon atmosphere, the preheated Mg metal is melted by multiple additions to form a Mg melt.

[0077] 1.3) After heating the Mg melt to 700 - 740 °C, the preheated Ni metal and La metal are added to obtain an initial mixture.

[0078] 1.4) After the initial mixture is completely melted, it is stirred, the impurities on the surface of the initial mixture are removed, and it is left standing for 10 - 30 min to obtain a Mg-Ni-La alloy melt.

[0079] The Mg-Ni-La alloy melt can be atomized using an atomization device (such as Figure 1 ). The atomization device includes an alloy liquid tank 2, a powder making tank 3, and an argon gas cylinder 4. The argon gas cylinder 4 provides an inert protection atmosphere for the alloy liquid tank 2 and the powder making tank 3. The bottom of the alloy liquid tank 2 is a turntable 21, and the turntable 21 is provided with a plurality of nozzles 22 that penetrate through the alloy liquid tank and the powder making tank.

[0080] Such as Figure 1 shown, the melting module is a melting crucible 1. The Mg-Ni-La alloy melt is obtained and enters the alloy liquid tank 2 through a circulation pipeline. The powder making tank 3 is in a sealed argon atmosphere. The gas supply module is mainly the argon gas cylinder 4, which supplies argon to protect the Mg-Ni-La alloy melt from oxidation.

[0081] The Mg-Ni-La alloy melt in the powder making tank 3 passes through a plurality of (for example, 6 can be set) nozzles 22. Under the rotation of the turntable 21, small droplets are thrown out and solidify into Mg-Ni-La alloy powder when they meet the wall of the powder making tank 3. The powder making tank 3 is in a vacuum, slightly positive pressure, about 1 - 5 kPa, and the powder making tank wall is provided with a circulating water cooling coil.

[0082] Among them, step 2) specifically includes the following steps:

[0083] 2.1) Inject the Mg-Ni-La alloy melt into the alloy liquid tank. The temperature in the alloy liquid tank is 800 - 900 °C, argon is filled, and the pressure of the alloy liquid tank is 0.15 - 0.3 MPa.

[0084] 2.2) The Mg-Ni-La alloy melt enters the powder making tank through the nozzles of the rotating middle turntable and is atomized into fine droplets. The powder making tank is in an argon atmosphere of 1 - 5 kPa, the nozzle rotation speed is 1400 - 1600 r / min, and the nozzle diameter is 5 - 10 mm.

[0085] 2.3) The fine droplets solidify into Mg-Ni-La alloy powder with a particle size of 20 - 150 μm in the powder making tank.

[0086] The component of the metal film is Cu. In step 5), it specifically includes the following steps:

[0087] 5.1) Prepare a CuO coating solution with a concentration of 40 - 90 g / L;

[0088] 5.2) Add the tablets after step 4) and stir;

[0089] 5.3) Take out after stirring for 8 - 12 min to obtain the initial hydrogen storage alloy with a uniformly coated CuO film;

[0090] 5.4) Under the condition of 180 - 220 °C, introduce hydrogen to reduce the CuO film, precipitate oxygen, and form a hydrogen storage alloy with a metal film having a porous structure.

[0091] Among them, step 5.1) specifically includes:

[0092] Add Cu(NO3)2·3H2O to deionized water, heat to 90 - 120 °C and stir;

[0093] Add NH4HCO3 with a concentration of 2.5 - 3.5 g / L in multiple additions. After the addition is completed, stir at a constant temperature to obtain a CuO coating solution with a concentration of 40 - 90 g / L.

[0094] The present invention will be described in detail below through specific examples and comparative examples.

[0095] Example 1

[0096] In this example, for the Mg-Ni-La alloy of the magnesium-based alloy used for cyclic hydrogen storage and release, the elemental content ratio is 9% for Ni, 1.5% for La, and the rest is Mg. The method for preparing the magnesium-based alloy used for cyclic hydrogen storage and release specifically includes the following steps: Weigh Mg, Ni, and La elemental substances. Among them, the weighed masses of Mg and La are 1.1 times the content ratio, and preheat them at 200 °C respectively; in an argon environment, melt the preheated Mg elemental substance. The addition method of the Mg elemental substance is multiple additions. After all the Mg elemental substance is melted, heat the melt to 720 °C, add the preheated Ni and La elemental substances. After all are melted, stir and clean the surface impurities of the melt, and let it stand for 20 min to obtain the Mg-Ni-La alloy melt.

[0097] Inject the Mg-Ni-La alloy melt into the alloy liquid storage bin. The temperature in the alloy liquid storage bin is 850 °C, fill it with argon, and the pressure of the alloy liquid storage bin is 0.2 Mpa; the Mg-Ni-La alloy melt enters the powder-making bin through the nozzle of the rotating turntable and is atomized into fine droplets. The powder-making bin is in an argon environment of 4 kPa, the nozzle rotation speed is 1500 r / min, and the nozzle diameter is 7 mm; the fine droplets solidify into Mg-Ni-La alloy powder with an average particle size of 50 μm spherical shape in the powder-making bin.

[0098] Under argon protection, use a high-precision tablet press to press the Mg-Ni-La alloy powder into tablets, and press the tablets to a compactness of 60%; perform annealing treatment on the tablets. The annealing conditions are: stand still at 300 °C for 3 h, and then cool down with the furnace.

[0099] Add 60 g of Cu(NO3)2·3H2O to 1 L of deionized water, heat it to 100 °C and stir. Add NH4HCO3 with a concentration of 3 g / L in multiple additions, with a total addition amount of 1 L. After the addition is completed, stir at a constant temperature, add 1 kg of tablets, take them out after 10 min, and obtain tablets uniformly coated with a CuO film. Reduce the CuO film with hydrogen at 200 °C, oxygen precipitates from the film, and the CuO film becomes a porous copper film, obtaining a hydrogen storage magnesium-based alloy coated with a porous copper film.

[0100] For the magnesium-based alloy obtained in this example, the mass ratio of Cu to the Mg-Ni-La alloy is 0.001:1.

[0101] Example 2

[0102] On the basis of Example 1, Example 2 adjusts the following parameters.

[0103] For the element content ratio in the Mg-Ni-La alloy of the magnesium-based alloy, Ni is 9%, La is 0.1%, and the rest is Mg.

[0104] Example 3

[0105] On the basis of Example 1, Example 3 adjusts the following parameters.

[0106] For the element content ratio in the Mg-Ni-La alloy of the magnesium-based alloy, Ni is 9%, La is 3%, and the rest is Mg.

[0107] Example 4

[0108] On the basis of Example 1, Example 4 adjusts the following parameters.

[0109] In the Mg-Ni-La alloy of the magnesium-based alloy, the element content ratio is 14% for Ni, 1.5% for La, and the rest is Mg.

[0110] Example 5

[0111] Based on Example 1, Example 5 adjusts the following parameters.

[0112] Press the tablet to a compactness of 70%.

[0113] Example 6

[0114] Based on Example 1, Example 6 adjusts the following parameters.

[0115] Prolong the time of the tablet in the CuO coating solution to obtain a tablet with a uniformly coated CuO film. For the magnesium-based alloy in this example, the mass ratio of Cu to the Mg-Ni-La alloy is 0.002:1.

[0116] Example 7

[0117] Based on Example 1, Example 7 adjusts the following parameters.

[0118] Fine droplets solidify into spherical Mg-Ni-La alloy powder with an average particle size of 200 μm in the powder-making bin.

[0119] Comparative Example 1

[0120] Based on Example 1, Comparative Example 1 adjusts the following parameters.

[0121] In the Mg-Ni-La alloy of the magnesium-based alloy, the element content ratio is 20% for Ni, 1.5% for La, and the rest is Mg.

[0122] Comparative Example 2

[0123] Based on Example 1, Comparative Example 2 adjusts the following parameters.

[0124] In the Mg-Ni-La alloy of the magnesium-based alloy, the element content ratio is 9% for Ni, 5% for La, and the rest is Mg.

[0125] Comparative Example 3

[0126] Based on Example 1, Comparative Example 3 adjusts the following parameters.

[0127] The Mg-Ni-La alloy of the magnesium-based alloy is changed to an Mg-Ni alloy without La. The element content ratio is 9% for Ni, and the rest is Mg.

[0128] Comparative Example 4

[0129] Based on Example 1, Comparative Example 4 adjusted the following parameters.

[0130] The tablet was pressed to a compactness of 40%.

[0131] Comparative Example 5

[0132] Based on Example 1, Comparative Example 5 adjusted the following parameters.

[0133] The tablet was pressed to a compactness of 80%.

[0134] Comparative Example 6

[0135] Based on Example 1, Comparative Example 6 adjusted the following parameters.

[0136] The step of preparing the CuO coating solution and coating the tablet with the CuO film was omitted.

[0137] Comparative Example 7

[0138] Based on Example 1, Comparative Example 7 adjusted the following parameters.

[0139] In the magnesium-based alloy of this example, the mass ratio of Cu to the Mg-Ni-La alloy was 0.003:1.

[0140] Comparative Example 8

[0141] Based on Example 1, Comparative Example 8 adjusted the following parameters.

[0142] The fine droplets solidified into spherical Mg-Ni-La alloy powder with an average particle size of 40 μm in the powder-making bin.

[0143] Comparative Example 9

[0144] Based on Example 1, Comparative Example 9 adjusted the following parameters.

[0145] The fine droplets solidified into spherical Mg-Ni-La alloy powder with an average particle size of 250 μm in the powder-making bin.

[0146] Comparative Example 10

[0147] Comparative Example 10 was the Ma-Ni-La alloy obtained by using the preparation method of Example 1 of Patent CN114507798A.

[0148] Performance Test

[0149] The magnesium-based alloys obtained in Examples 1-7 and Comparative Examples 1-10 were subjected to cyclic hydrogen storage and release performance tests. The specific test process and conditions were as follows: The magnesium-based alloy was placed in a hydrogen storage tank, the hydrogen charging amount was 1000 L, the temperature was heated to 150 °C during the hydrogen charging process, the heating was stopped, and the subsequent temperature rise was provided by the heat released during hydrogen absorption. The hydrogen charging pressure was 1 Mpa, and the total time consumed was 5.3 h; during the hydrogen release process, the hydrogen release flow rate was set at 3 L / min, and the time consumed was 5.3 h, and the hydrogen release temperature was measured.

[0150] A 100-cycle test was carried out to observe the appearance of the magnesium-based alloy particulate material and calculate the attenuation of the hydrogen storage capacity of the magnesium-based alloy.

[0151] Examples 1-7 and Comparative Examples 1-10 were subjected to the above tests, and the results are shown in Table 1. At the same time, Figures 2 - 5 The performance test results of the magnesium-based alloy of Example 1 were given.

[0152] Table 1 Test results of Examples 1-7 and Comparative Examples 1-10

[0153]

[0154]

[0155] It can be seen from the above results that for the magnesium-based alloys of Examples 1-7, the hydrogen storage amounts of the alloys charged with hydrogen at 1 Mpa / 150 °C for 5.3 h were all greater than 6.2 wt%, the initial hydrogen release temperature was between 280 and 320 °C, and after 100 cycles, the attenuation conditions were all in good shape and there was no obvious attenuation of the hydrogen storage amount.

[0156] After increasing the Ni content or changing the La content, although the attenuation conditions were still in good shape and there was no obvious attenuation of the hydrogen storage amount after 100 cycles, the hydrogen storage amount decreased significantly (Comparative Examples 1, 2, and 3). When the tablet compactness was reduced, signs of powdering of the particles appeared (Comparative Example 4), and when the tablet compactness was increased, the hydrogen storage amount decreased significantly (Comparative Example 5). For the metal film without wrapping, the particles were powdered and the hydrogen storage amount decreased by 5% (Comparative Example 6). When the metal film content was too high, there was no obvious attenuation of the hydrogen storage amount, but the hydrogen storage amount decreased significantly (Comparative Example 7). If the particle size of the Mg-Ni-La alloy powder was too small, it could not be pressed into tablets (Comparative Example 8), and if the particle size of the Mg-Ni-La alloy powder was too large, the hydrogen storage amount decreased significantly (Comparative Example 9). Using an alloy electrode for atomization powder making instead of the melt atomization of the present invention, the hydrogen storage amount decreased significantly (Comparative Example 10).

[0157] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once they learn of the basic inventive concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art can make various changes and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A magnesium-based alloy for cyclic hydrogen storage, characterized in that, The magnesium-based alloy includes a Mg-Ni-La alloy and a metal film. The Mg-Ni-La alloy is composed of Mg, Ni and La elements, wherein the content of Ni is 8.0-14.0wt%, the content of La is 0.1-3.0wt%, and the Mg-Ni-La alloy is a tablet formed by agglomeration of particles. The tablet is coated with a metal film, the metal film has a porous structure, the component of the metal film is Cu, and the mass ratio of the metal film to the Mg-Ni-La alloy is (0.001-0.002): 1; The shape of the tablet particles is spherical, and the tablet compactness is 50%~70%; The thickness of the metal film is 30~50μm, and the pore size of the metal film is 0.5~2μm.

2. The magnesium-based alloy according to claim 1, characterized in that, The Ni content is 8.0~9.0wt%, and the La content is 1.5~3.0wt%.

3. The magnesium-based alloy according to claim 1 or 2, characterized in that, The particle size of the tablet particles is 20-150 μm.

4. A method for preparing a magnesium-based alloy for cyclic hydrogen storage and release, which prepares the magnesium-based alloy for cyclic hydrogen storage and release as described in any one of claims 1-3, characterized in that, The specific steps include: 1) According to the content of Mg, Ni and La elements, Mg-Ni-La alloy melt is obtained; 2) atomizing the Mg-Ni-La alloy melt to form Mg-Ni-La alloy powder; 3) Under argon protection, the Mg-Ni-La alloy powder is pressed into tablets; 4) The tablets are annealed at 300-310°C for 2-5 hours and then cooled in the furnace; 5) After step 4), the surface of the tablet is coated with a metal film to obtain a magnesium-based alloy for cyclic storage and release of hydrogen.

5. The preparation method according to claim 4, characterized in that, Step 1) specifically includes the following steps: 1.1) Weigh Mg, Ni and La, and preheat them at 180-220℃ respectively; 1.2) Under a protective atmosphere, the preheated Mg element is melted by multiple additions to form a Mg melt; 1.3) After the Mg melt is heated to 700-740°C, the preheated Ni and La are added to obtain an initial mixture; 1.4) After the initial mixture is completely melted, stir it, clean the impurities on the surface of the initial mixture, and let it stand for 10 to 30 minutes to obtain a Mg-Ni-La alloy melt.

6. The preparation method according to claim 5, characterized in that, The protective atmosphere is an argon environment, and the masses of the Mg and La single substances weighed are 1.05 to 1.1 times of their content specific gravity.

7. The preparation method according to claim 4, wherein The Mg-Ni-La alloy melt is atomized by an atomizing device, which includes an alloy liquid bin, a powder making bin and an argon gas cylinder, the argon gas cylinder provides an inert protective atmosphere for the alloy liquid bin and the powder making bin, the bottom of the alloy liquid bin is a turntable, and the turntable is provided with a plurality of nozzles penetrating the alloy liquid bin and the powder making bin; Wherein, step 2) specifically includes the following steps: 2.1) Inject the Mg-Ni-La alloy melt into the alloy liquid tank. The temperature in the alloy liquid tank is 800~900℃, filled with argon gas, and the pressure of the alloy liquid tank is 0.15~0.3Mpa; 2.2) The Mg-Ni-La alloy melt enters the powder making chamber through the nozzle of the rotating turntable and is atomized into fine droplets. The powder making chamber is in an argon gas environment of 1~5kPa, the nozzle speed is 1400~1600r / min, and the nozzle diameter is 5~10mm; 2.3) The fine droplets solidify into Mg-Ni-La alloy powder with a particle size of 20~150μm in the powder making bin.

8. The preparation method according to claim 4, characterized in that, The component of the metal film is Cu; Among them, step 5) specifically includes the following steps: 5.1) Prepare a CuO coating solution with a concentration of 40 - 90 g / L; 5.2) Add the tablet after step 4) and stir; 5.3) Take it out after stirring for 8 - 12 min to obtain the initial hydrogen storage alloy with a uniformly coated CuO film; 5.4) Under the condition of 180 - 220 °C, introduce hydrogen to reduce the CuO film, precipitate oxygen, and form a hydrogen storage magnesium-based alloy with a metal film coated with a porous structure.

9. The preparation method according to claim 8, characterized in that, Step 5.1) specifically includes: Add Cu(NO3)2·3H2O to deionized water, heat to 90 - 120 °C and stir; Add NH4HCO3 with a concentration of 2.5 - 3.5 g / L in multiple additions. After the addition is completed, stir at a constant temperature to obtain a CuO coating solution with a concentration of 40 - 90 g / L.

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