Preparation Method of Graphene-Reinforced Mg-Ni Hydrogen Storage Alloy Powder and Hydrogen Storage Material

Abstract

The present invention discloses a preparation method of graphene-reinforced Mg-Ni hydrogen storage alloy powder, which includes Step 1: raw material selection; Step 2: preparation of Mg-Ni pre-alloy; Step 3: melt spinning; Step 4: high-energy ball milling. The present invention solves the problems of slow hydrogen absorption and desorption rates and low hydrogen storage capacity of the hydrogen storage materials prepared by the current preparation methods. The present invention also discloses a reversible hydrogen-absorbing and desorbing magnesium-based solid hydrogen storage material, which is prepared by using the preparation method of the graphene-reinforced Mg-Ni hydrogen storage alloy powder of the present invention, achieving high hydrogen absorption and desorption rates and low hydrogen absorption and desorption temperatures of the hydrogen storage material.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen storage and transportation in hydrogen energy, and relates to a preparation method of graphene-reinforced Mg-Ni hydrogen storage alloy powder, and also relates to a reversible hydrogen-absorbing and -desorbing magnesium-based solid hydrogen storage material. Background Art

[0002] Hydrogen has high chemical reactivity, environmental friendliness and renewability, and is an ideal energy carrier. However, hydrogen storage is one of the main bottlenecks restricting the development of hydrogen energy. At present, the main hydrogen storage technologies are high-pressure gaseous hydrogen storage and cryogenic liquefied hydrogen storage, and both hydrogen storage methods have technical defects that cannot be ignored. High-pressure gaseous hydrogen storage has disadvantages such as low volumetric energy density, high requirements for the pressure resistance of containers, insecurity and time consumption in the hydrogenation process; although cryogenic liquefied hydrogen storage has a high volumetric energy density, it has high energy consumption for cryogenic liquefied hydrogen storage, large evaporation losses, high requirements for the heat insulation material of the storage tank and supporting equipment, high manufacturing cost, and poor economic competitiveness. Solid-state hydrogen storage stores hydrogen in the lattice interstices or defects of some materials by physical adsorption or chemical reaction. Its advantages are that this hydrogen storage material has a high volumetric hydrogen storage density, is safe and efficient, and is also very convenient in terms of storage and transportation. At present, solid-state storage systems based on metal hydrides have shown the potential to be quite safe and capable of reversibly storing large amounts of hydrogen, and have become an increasingly attractive choice for hydrogen storage materials.

[0003] Magnesium hydride is one of the most studied hydrogen storage materials in solid-state hydrogen storage materials, mainly because of its high theoretical hydrogen absorption capacity (7.6 wt%) and low production cost. Magnesium hydride (MgH 2 ) has a rutile crystal structure (close-packed hexagonal lattice, and its cations occupy half of the octahedral voids). However, its hydrogen absorption / desorption kinetic rate is slow and the hydrogen absorption / desorption temperature is too high to be difficult to apply in practice. Patent CN201910357757.9 uses Mg 2The Ni alloy powder and nickel-plated carbon nanotubes are respectively pre-treated by high-current electron beam pulsed surface irradiation, then mechanically alloyed by planetary ball milling, and finally subjected to high-current electron beam pulsed surface irradiation treatment. The obtained magnesium-based hydrogen storage alloy has a maximum hydrogen absorption of 2.76 wt.% and a maximum hydrogen desorption of 1.88 wt.% at 250 °C, and it takes 120 s to complete 80% of the hydrogen absorption. Patent CN201010536311.1 discloses a method of ball milling and mixing magnesium powder, nickel powder, cerium powder and graphite under the protection of an inert gas, and then synthesizing a composite hydrogen storage material by microwave heating after pressing. The hydrogen absorption capacity is measured to reach 3.6 wt.% at 573 K and 4 MPa. Patent CN202210740595.9 combines the friction stir processing technology with a smooth file, and no post-treatment such as sieving and ball milling is required. The prepared magnesium-lithium hydrogen storage material absorbs hydrogen up to 2.8 wt.% in 60 min at 350 °C, and the hydrogen desorption amount is 0.9 wt.% in 65 min. The hydrogen storage alloys prepared by the above preparation methods all have problems such as high hydrogen absorption and desorption temperature, slow hydrogen absorption and desorption rate, and low hydrogen storage capacity. Therefore, it is an urgent problem to find a preparation technology for a reversible hydrogen absorption and desorption hydrogen storage material with a high hydrogen absorption and desorption rate, a low hydrogen absorption and desorption temperature, a long cycle service life, and a high specific capacity. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing graphene-reinforced Mg-Ni hydrogen storage alloy powder, which solves the problems of slow hydrogen absorption and desorption rate and low hydrogen storage capacity of the hydrogen storage materials prepared by the current preparation methods.

[0005] Another purpose of the present invention is to provide a reversible hydrogen absorption and desorption magnesium-based solid hydrogen storage material, which realizes a high hydrogen absorption and desorption rate and a low hydrogen absorption and desorption temperature of the hydrogen storage material.

[0006] The first technical solution adopted by the present invention is a method for preparing graphene-reinforced Mg-Ni hydrogen storage alloy powder, which is specifically implemented according to the following steps:

[0007] Step 1, Raw material selection

[0008] Select graphene nanosheets, Mg-Ni master alloy and Mg blocks as raw materials;

[0009] Step 2, Preparation of Mg-Ni pre-alloy

[0010] The Mg-Ni master alloy and Mg blocks are ultrasonically cleaned and then placed in an alumina crucible, and melted in an argon atmosphere to obtain a prefabricated Mg-Ni alloy;

[0011] Step 3, Melt spinning

[0012] The prefabricated Mg-Ni alloy is obtained as Mg-Ni amorphous ribbon by melt spinning method;

[0013] Step 4, High-energy ball milling

[0014] Place the Mg-Ni amorphous ribbon in a ball milling jar, add graphene nanosheets to the ball milling jar, then place the ball milling jar in a vacuum glove box, fill it with argon and tighten it, and then place the ball milling jar filled with argon in a ball mill for ball milling treatment to obtain graphene-Mg-Ni composite hydrogen storage powder, and the preparation is completed.

[0015] The characteristics of the first technical solution of the present invention also lie in:

[0016] The mass ratio of graphene nanosheets, magnesium-nickel master alloy and Mg blocks is 2:90-95:3-8.

[0017] The number of layers of graphene nanosheets does not exceed 10 layers, the mass percentage of Ni content in the magnesium-nickel master alloy is 30-35%, and the mass purity of Mg blocks is 99%.

[0018] The condition parameters of ultrasonic cleaning in step 2 are: ultrasonic frequency 40 kHz, power 700 W, and cleaning time 15 minutes.

[0019] The condition parameters of melting in step 2 are: heating rate 8 °C / min, heating to 700-800 °C and holding for 10 min, then cooling with the furnace, and repeating the heating to cooling process 2-3 times.

[0020] The thickness of the Mg-Ni amorphous ribbon is 50-100 μm and the width does not exceed 10 mm.

[0021] The condition parameters of the melt spinning method in step 3 are: heating to 830 °C, spinning (rapid quenching) speed 2000 r / min, cooling rate 10 6 °C / min, and the diameter of the cooling tube is 250 mm.

[0022] The condition parameters of ball milling treatment in step 4 are: ball milling swing frequency 1200 r / min for ball milling for 6 hours, and the ball-to-material ratio is 20:1.

[0023] The ball milling jar is made of 304 stainless steel, and the grinding balls are GCr15 steel balls.

[0024] The second technical solution adopted by the present invention is a reversible hydrogen absorption and desorption magnesium-based solid hydrogen storage material, which is prepared by using the preparation method of graphene-reinforced Mg-Ni hydrogen storage alloy powder of the present invention.

[0025] The beneficial effects of the present invention are:

[0026] The preparation method of graphene-reinforced Mg-Ni hydrogen storage alloy powder of the present invention is successively prepared by melting, melt spinning, and high-energy ball milling treatment. 1) After melting, Ni in the alloy exists as an intermetallic compound Mg 2In the presence of Ni phase, the Mg-Ni hydrogen storage system rich in Mg has excellent amorphous forming ability. Through the melt spinning technology, it is easy to prepare Mg-Ni nanocrystalline and / or amorphous hydrogen storage alloys, which can increase the reaction sites with hydrogen atoms and promote the hydrogenation reaction;

[0027] 2) After the alloy added with graphene absorbs hydrogen by ball milling, two adjacent edge C atoms will dissociate the nearby MgH 2 into components H and Mg-H, and form C-H and C-Mg-H bonds respectively. When hydrogen is initially released, C-H releases hydrogen first, and electrons are fed back from C to Mg. This electron feedback weakens the Mg-H bond and enhances the hydrogen release of MgH 2 Moreover, C in the C-Mg-H part contributes more positive charge to H than Mg, which also leads to the instability of the Mg-H component, thus promoting the occurrence of reversible hydrogen absorption and desorption reactions;

[0028] 3) Nickel has a good catalytic effect on the adsorption and desorption of hydrogen;

[0029] 4) The refinement of grains and the existence of a large number of grain boundaries and lattice defects introduced during the ball milling process also promote the improvement of the hydrogen storage performance of the alloy.

[0030] The reversible hydrogen absorption and desorption magnesium-based solid-state hydrogen storage material of the present invention has the characteristics of high hydrogen absorption and desorption rate, low hydrogen absorption and desorption temperature, long cycle service life, and high specific capacity. Brief Description of the Drawings

[0031] Figure 1 is the micrograph of the graphene-Mg-Ni composite hydrogen storage powder prepared by the preparation method of the graphene-reinforced Mg-Ni hydrogen storage alloy powder of the present invention;

[0032] Figure 2 is the XRD diffraction pattern after melting, melt spinning, and ball milling with graphene added respectively in the present invention;

[0033] Figure 3 is the hydrogen absorption kinetic curve of the graphene-Mg-Ni hydrogen storage alloy at different temperatures;

[0034] Figure 4 is the hydrogen desorption kinetic curve of the graphene-Mg-Ni hydrogen storage alloy at different temperatures;

[0035] Figure 5 is the schematic PCT curve of the hydrogen absorption and desorption thermodynamics of the graphene-Mg-Ni hydrogen storage alloy. Detailed Description of the Invention

[0036] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0037] Example 1

[0038] This embodiment provides a method for preparing graphene-reinforced Mg-Ni hydrogen storage alloy powder, which is specifically implemented according to the following steps:

[0039] Step 1: Raw material selection

[0040] Select graphene nanosheets, Mg-Ni master alloy, and Mg blocks as raw materials. The mass ratio of graphene nanosheets, Mg-Ni master alloy, and Mg blocks is 2:93:5. The number of layers of graphene nanosheets is 10. The mass percentage of Ni in the Mg-Ni master alloy is 32%, and the mass purity of the Mg block is 99%;

[0041] Step 2: Preparation of Mg-Ni pre-alloy

[0042] The Mg-Ni master alloy and Mg blocks are ultrasonically cleaned and then placed in an alumina crucible, and melted in an argon atmosphere to obtain a prefabricated Mg-Ni alloy. The condition parameters of ultrasonic cleaning are: frequency 40 kHz, power 700 W, cleaning frequency 15 minutes. The condition parameters of melting are: heating rate 8 °C / min, heating to 750 °C and holding for 10 min, then cooling with the furnace, and repeating the heating and cooling process 2 times;

[0043] Step 3: Melt spinning

[0044] The prefabricated Mg-Ni alloy is processed by melt spinning to obtain a Mg-Ni amorphous ribbon with a thickness of 80 μm and a width of 10 mm. The condition parameters of melt spinning are: heating to 830 °C, spinning (rapid quenching) speed 2000 r / min, cooling rate 10 6 °C / min, and the diameter of the cooling tube is 250 mm;

[0045] Step 4: High-energy ball milling

[0046] The Mg-Ni amorphous ribbon is placed in a ball milling jar, and graphene nanosheets are added to the ball milling jar. Then the ball milling jar is first placed in a vacuum glove box, filled with argon and tightened. Then the ball milling jar filled with argon (the ball milling jar is made of 304 stainless steel, and the grinding balls are GCr15 steel balls) is placed in a ball mill for ball milling treatment to obtain graphene-Mg-Ni composite hydrogen storage powder, and the preparation is completed. As Figure 1 shown in the microscopic morphology of the graphene-Mg-Ni composite hydrogen storage powder, the particle size is about 200 - 300 nanometers; the condition parameters of ball milling treatment are: ball milling swing frequency 1200 r / min, ball milling for 6 hours, and the ball-to-material ratio is 20:1.

[0047] This embodiment also provides a reversible hydrogen-absorbing and desorbing magnesium-based solid hydrogen storage material, which is prepared by using the preparation method of the graphene-reinforced Mg-Ni hydrogen storage alloy powder of this embodiment. Specifically, the powder prepared in step 4 of this embodiment is pressed into a tablet shape by a tablet press as the hydrogen storage material.

[0048] Hydrogen storage performance detection

[0049] Through the PCT curve test, the hydrogen absorption and desorption platform pressure of the alloy and the hydrogen absorption amount of the alloy forming hydride can be obtained. The test is carried out using a semi-automatic PCT hydrogen storage tester. Open the PCT test control interface, input the hydrogen absorption and desorption pressure step, the waiting time for hydrogen absorption stability, the highest pressure at the end of hydrogen absorption, input the file name, and run. The program automatically performs the PCT test according to the set pressure step and automatically judges whether the hydrogen absorption and desorption stable state is reached. When the final hydrogen absorption end pressure reaches the set highest value, it automatically switches to the hydrogen desorption test until the final hydrogen desorption ends, completing the test.

[0050] Through the hydrogen absorption and desorption curve and kinetic tests, the hydrogen absorption and desorption rate can be obtained. The test is also carried out using a semi-automatic PCT hydrogen storage tester. When performing the hydrogen absorption and desorption curve and kinetic tests, open the kinetic test control interface, input the predetermined initial system pressure, sample pressure, input the file name, and run. The system automatically fills hydrogen to the set pressure. After the pressure and temperature are stable, the valve is automatically opened for kinetic measurement. The sampling rate can be set starting from 1 s and automatically ends after reaching the set kinetic test time.

[0051] The materials prepared in steps 2, 3, and 4 of this example are respectively subjected to X-ray diffraction analysis, as Figure 2 shown. The XRD diffraction pattern after melting shows Mg 2 Ni and Mg. Compared with the previous one, the XRD pattern after melt spinning has wider and more disordered diffraction peaks and few sharp peaks, which are typical characteristics of amorphous. It shows that an amorphous Mg-Ni alloy is produced after melt spinning. After adding graphene and ball milling, it can be seen from the pattern that the amorphous phase decreases after ball milling. This is because the amorphous body is in a relatively stable metastable state. When the metastable amorphous alloy is vibrated and the temperature rises, the diffusion and migration of atoms will be enhanced accordingly. When the energy of the system reaches the energy for the glassy state to transform into the crystalline state and exceeds the barrier height, the amorphous alloy will crystallize.

[0052] The hydrogen absorption and desorption kinetics test is carried out on the graphene-Mg-Ni composite hydrogen storage powder prepared in step 4 of this example, as Figure 3 shown. The hydrogen absorption kinetics curves of the graphene-Mg-Ni composite hydrogen storage powder at different temperatures. The kinetic performance of this powder is good and the hydrogen absorption rate is fast; at 3.5 MPa and 553 K, the maximum hydrogen storage capacity of this powder is 4.1 wt.%, and the hydrogen absorption amount can reach 3.5 wt.% within 2 min; at 623 K, the maximum hydrogen storage capacity of this powder is 4.32 wt.%, and the hydrogen absorption amount can reach more than 4 wt.% within 2 min.

[0053] From Figure 4It can be seen that the hydrogen desorption kinetic curves of graphene-Mg-Ni hydrogen storage alloy powder at different temperatures show that when desorbing hydrogen at 553K, 62.5% of the maximum hydrogen storage capacity can be released within 120 minutes. When the temperature is increased to 623K, about 94.4% of the maximum hydrogen storage capacity can be released in about 4 minutes, showing excellent hydrogen desorption performance.

[0054] It can be seen from Figure 5 the PCT curve in that there are two obvious plateau pressures. At a temperature of 553K, the side with the lower plateau pressure is the plateau pressure of elemental magnesium. The hydrogen absorption plateau pressure is about 0.08MPa, and the hydrogen desorption plateau pressure is about 0.07MPa; the side with the higher plateau pressure is the plateau pressure of Mg 2 Ni. The hydrogen absorption plateau pressure is about 0.21MPa, and the hydrogen desorption plateau pressure is about 0.13MPa. At a temperature of 623K, the side with the lower plateau pressure is the plateau pressure of elemental magnesium. The hydrogen absorption plateau pressure is about 0.56MPa, and the hydrogen desorption plateau pressure is about 0.46MPa; the side with the higher plateau pressure is the plateau pressure of Mg 2 Ni. The hydrogen absorption plateau pressure is about 1.02MPa, and the hydrogen desorption plateau pressure is about 0.68MPa.

[0055] From the above, it can be known that the preparation method of the graphene-reinforced Mg-Ni hydrogen storage alloy powder of the present invention has the following advantages compared with the prior art:

[0056] 1) Mg 2 Ni is a representative of AB 2 type alloy. After alloying with Mg, Mg 2 Ni itself can reversibly absorb and desorb hydrogen and has a hydrogen storage capacity of 3.6wt%.

[0057] 2) The melt spinning technology refines and homogenizes the alloy, thus reducing the grain size of MgH2, which is beneficial to the diffusion and dissociation of hydrogen, and greatly improving the hydrogen absorption / dehydrogenation kinetics.

[0058] 3) The addition of Ni plays a good catalytic role in the hydrogen absorption and desorption reactions of Mg.

[0059] 4) Compared with metallic Mg powder, the prepared graphene-Mg-Ni composite hydrogen storage powder can absorb and desorb hydrogen at 3.5MPa and 623K, and has good hydrogen absorption and desorption kinetic performance and is relatively easy to activate.

[0060] Example 2

[0061] This example provides a preparation method of graphene-reinforced Mg-Ni hydrogen storage alloy powder, which is specifically implemented according to the following steps:

[0062] Step 1, raw material selection

[0063] Graphene nanosheets, magnesium-nickel master alloy, and Mg blocks were selected as raw materials. The mass ratio of graphene nanosheets, magnesium-nickel master alloy, and Mg blocks was 2:90:3. The number of layers of graphene nanosheets was 8. The mass percentage of Ni in the magnesium-nickel master alloy was 30%, and the mass purity of the Mg blocks was 99%.

[0064] Step 2: Preparation of Mg-Ni pre-alloy

[0065] The magnesium-nickel master alloy and Mg blocks were ultrasonically cleaned and then placed in an alumina crucible, and melted in an argon atmosphere to obtain a prefabricated Mg-Ni alloy. The condition parameters of ultrasonic cleaning were: frequency 40 kHz, power 700 W, cleaning frequency 15 minutes. The condition parameters of melting were: heating rate 8 °C / min, heating to 700 °C and holding for 10 min, and then cooling with the furnace. The heating and cooling process was repeated 3 times.

[0066] Step 3: Melt spinning

[0067] The prefabricated Mg-Ni alloy was processed by melt spinning to obtain a Mg-Ni amorphous ribbon with a thickness of 50 μm and a width of 8 mm. The condition parameters of melt spinning were: heating to 830 °C, spinning (quick quenching) speed 2000 r / min, cooling rate 10 6 °C / min, and the diameter of the cooling tube 250 mm.

[0068] Step 4: High-energy ball milling

[0069] The Mg-Ni amorphous ribbon was placed in a ball milling jar, and graphene nanosheets were added to the ball milling jar. Then the ball milling jar was first placed in a vacuum glove box, filled with argon and tightened. Then the ball milling jar filled with argon (the ball milling jar was made of 304 stainless steel, and the grinding balls were GCr15 steel balls) was placed in a ball mill for ball milling treatment to obtain graphene-Mg-Ni composite hydrogen storage powder, and the preparation was completed. The condition parameters of ball milling treatment were: ball milling oscillation frequency 1200 r / min, ball milling for 6 hours, and ball-to-powder ratio 20:1.

[0070] This embodiment also provides a reversible hydrogen absorption and desorption magnesium-based solid hydrogen storage material, which is prepared by using the preparation method of graphene-enhanced Mg-Ni hydrogen storage alloy powder in this embodiment. Specifically, the powder prepared in step 4 of this embodiment was pressed into a tablet shape by a tablet press as the hydrogen storage material.

[0071] Example 3

[0072] This embodiment provides a preparation method of graphene-enhanced Mg-Ni hydrogen storage alloy powder, which is specifically implemented according to the following steps:

[0073] Step 1: Raw material selection

[0074] Graphene nanosheets, magnesium-nickel master alloy, and Mg blocks were selected as raw materials. The mass ratio of graphene nanosheets, magnesium-nickel master alloy, and Mg blocks was 2:95:8. The number of layers of graphene nanosheets was 10. The mass percentage of Ni in the magnesium-nickel master alloy was 35%, and the mass purity of the Mg block was 99%.

[0075] Step 2: Preparation of Mg-Ni pre-alloy

[0076] The magnesium-nickel master alloy and Mg blocks were ultrasonically cleaned and then placed in an alumina crucible, and melted in an argon atmosphere to obtain a prefabricated Mg-Ni alloy. The condition parameters of ultrasonic cleaning were: frequency 40 kHz, power 700 W, cleaning frequency 15 minutes. The condition parameters of melting were: heating rate 8 °C / min, heated to 800 °C and held for 10 min, then cooled in the furnace, and the heating and cooling process was repeated 3 times;

[0077] Step 3: Melt spinning

[0078] The prefabricated Mg-Ni alloy was processed by melt spinning to obtain a Mg-Ni amorphous ribbon with a thickness of 100 μm and a width of 10 mm. The condition parameters of melt spinning were: heated to 830 °C, the spinning (quick quenching) speed was 2000 r / min, the cooling rate was 10 6 °C / min, and the diameter of the cooling tube was 250 mm;

[0079] Step 4: High-energy ball milling

[0080] The Mg-Ni amorphous ribbon was placed in a ball milling tank, and graphene nanosheets were added to the ball milling tank. Then the ball milling tank was first placed in a vacuum glove box, filled with argon and tightened. Then the ball milling tank filled with argon (the ball milling tank was made of 304 stainless steel, and the grinding balls were GCr15 steel balls) was placed in a ball mill for ball milling treatment to obtain graphene-Mg-Ni composite hydrogen storage powder, and the preparation was completed. The condition parameters of ball milling treatment were: ball milling oscillation frequency 1200 r / min, ball milling for 6 hours, and the ball-to-powder ratio was 20∶1.

[0081] This embodiment also provides a reversible hydrogen absorption and desorption magnesium-based solid hydrogen storage material, which is prepared by using the preparation method of graphene-reinforced Mg-Ni hydrogen storage alloy powder in this embodiment. Specifically, the powder prepared in step 4 of this embodiment was pressed into a tablet shape by a tablet press as the hydrogen storage material.

Claims

1. A method for preparing graphene-enhanced Mg-Ni hydrogen storage alloy powder, characterized in that: Follow the steps below to implement it: Step 1: Raw material selection Selecting graphene nanosheets, magnesium-nickel master alloy and Mg block as raw materials, the mass ratio of the graphene nanosheets, magnesium-nickel master alloy and Mg block is 2:90-95:3-8, the number of layers of the graphene nanosheets does not exceed 10, the mass percentage of Ni in the magnesium-nickel master alloy is 30-35%, and the mass purity of the Mg block is 99%; Step 2: Preparation of Mg-Ni pre-alloy The magnesium-nickel master alloy and the Mg block are ultrasonically cleaned and placed in an alumina crucible, and smelted in an argon atmosphere to obtain a prefabricated Mg-Ni alloy; The smelting condition parameters in step 2 are: the heating rate is 8°C / min, the temperature is raised to 700-800°C and kept for 10 minutes, then cooled with the furnace, and the heating and cooling process are repeated 2-3 times; Step 3: Rapid quenching of the melt The prefabricated Mg-Ni alloy was subjected to a melt quenching method to obtain a Mg-Ni amorphous thin strip. The melt quenching method was performed under the following conditions: heating to 830°C, spinning speed of 2000 r / min, cooling rate of 10 6 °C / min, the cooling tube diameter is 250mm, the Mg-Ni amorphous ribbon has a thickness of 50-100μm and a width of no more than 10mm; Step 4: High Energy Ball Milling The Mg-Ni amorphous thin strip is placed in a ball mill, and graphene nanosheets are added to the ball mill. The ball mill is then placed in a vacuum glove box, filled with argon, and then tightened. The ball mill filled with argon is then placed in a ball mill for ball milling to obtain graphene-Mg-Ni composite hydrogen storage powder. The preparation is completed.

2. The method for preparing graphene-enhanced Mg-Ni hydrogen storage alloy powder according to claim 1, characterized in that: The ultrasonic cleaning conditions in step 2 are as follows: frequency 40 kHz, power 700 W, and cleaning time 15 min.

3. The method for preparing graphene-enhanced Mg-Ni hydrogen storage alloy powder according to claim 1, characterized in that: The conditions and parameters of the ball milling treatment in step 4 are: a ball milling frequency of 1200 r / min, ball milling for 6 hours, and a ball-to-material ratio of 20:

1.

4. The method for preparing graphene-enhanced Mg-Ni hydrogen storage alloy powder according to claim 1, characterized in that: The ball mill is made of 304 stainless steel, and the grinding balls are GCr15 steel balls.

5. Reversible hydrogen absorption and desorption magnesium-based solid hydrogen storage material, characterized in that: The powder is prepared by the method for preparing the graphene-enhanced Mg-Ni hydrogen storage alloy powder according to any one of claims 1 to 4.

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