Magnesium-based hydrogen storage material and method for producing the same

Abstract

The application discloses a magnesium-based hydrogen storage material and a preparation method thereof, and belongs to the technical field of hydrogen storage alloy materials and preparation thereof. The application improves hydrogen absorption and desorption kinetics of the existing magnesium-based hydrogen storage material, reduces hydrogen desorption activation energy thereof, and solves the problem that solid-state additives are difficult to uniformly distribute on the surface. The application realizes internal microstructure regulation and control through high-energy ball milling to prepare an amorphous / nanocrystalline structure, realizes uniform distribution of the solid-state additives on the surface and improvement of surface properties through co-ball milling of the alloy powder with two additives, Cu powder and carbon nanotubes, and explores the best adding proportion between the two additives through the complementary action between the two additives, so that the hydrogen absorption and desorption kinetics of the magnesium-based hydrogen storage alloy Mg 85 Ni5Ce 10 is significantly improved, and the hydrogen desorption activation energy thereof is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a magnesium-based hydrogen storage material and a preparation method thereof, and belongs to the field of hydrogen storage alloy materials and their preparation technology. BACKGROUND

[0002] Energy is the most important material basis to support the production and economic development of human society. The most commonly used fossil fuels, such as coal and oil, have been overexploited and used, which has caused serious energy depletion. It is of great significance to develop green energy with abundant reserves, high efficiency, safety and economy for the sustainable development of economy and society. Hydrogen, as one of the most abundant elements on earth, is expected to become a major secondary energy source in the late oil era due to its high combustion heat and clean pollution-free.

[0003] From the factors of volume hydrogen storage density, hydrogen storage energy consumption, safety and other factors, metal-based hydrogen storage material is currently considered to be one of the best hydrogen storage methods. At the same time, magnesium resources are abundant and low in price, so more and more researchers pay attention to it. However, the magnesium-based hydrogen storage material has a high hydrogen absorption and desorption temperature (300-400℃), poor kinetics and thermodynamics, and cannot meet the requirements of practical application without modification. This is mainly because of the slow dissociation of hydrogen on the surface of magnesium and the slow diffusion inside the alloy and hydride. Therefore, it is necessary to effectively improve the hydrogen absorption and desorption performance of magnesium-based alloy and provide an ideal magnesium-based hydrogen storage material for large-scale industrial promotion and as a future hydrogen storage and transportation. SUMMARY

[0004] The present application is to solve the problem of improving the hydrogen absorption and desorption kinetics of the existing magnesium-based hydrogen storage material, reducing the hydrogen desorption activation energy, and solving the problem of uniform distribution of solid additives on the surface, and provides a magnesium-based hydrogen storage material and a preparation method thereof.

[0005] The technical scheme of the present application is as follows:

[0006] One of the purposes of the present application is to provide a magnesium-based hydrogen storage material, which is prepared from copper powder, carbon nanotubes and Mg 85 Ni5Ce 10 alloy powder as raw materials by ball milling.

[0007] Further limited, the mass ratio of Mg 85 Ni5Ce 10 alloy powder, copper powder and carbon nanotubes is 7: (1-2): (1-2).

[0008] More limited, the mass ratio of Mg 85 Ni5Ce 10 alloy powder, copper powder and carbon nanotubes is 7:2:1.

[0009] Further limited, Mg 85 Ni5Ce 10 The mass ratio of the alloy powder, the copper powder and the carbon nanotube is 7:1:2.

[0010] Further limited, Mg 85 Ni5Ce 10 The particle size of the alloy powder is 100-200 mesh, the particle size of the copper powder is 200 mesh, and the diameter of the carbon nanotube is 5-10 nm.

[0011] The second object of the present application is to provide a preparation method of the above-mentioned magnesium-based hydrogen storage material. 85 Ni5Ce 10 The alloy powder, the copper powder and the carbon nanotube are mixed and placed in a ball mill tank, and ball milling treatment is performed to obtain the magnesium-based hydrogen storage material.

[0012] Further limited, the rotation speed of the ball milling treatment is 350 r / min, the ball milling time is 20 h, and the ball milling is stopped for 30 min every 30 min.

[0013] Further limited, the ball milling treatment is performed in a mode of forward and reverse rotation alternately.

[0014] Further limited, the ball-to-material ratio of the ball milling treatment is 20:1.

[0015] Further limited, the ball of the ball milling treatment is a stainless steel ball with a diameter of 4-8 mm.

[0016] The second object of the present application is to provide a magnesium-based hydrogen storage material prepared by the above-mentioned method.

[0017] Beneficial effects:

[0018] The present application adopts a method of simultaneously regulating the internal microstructure and the surface properties of the magnesium-based hydrogen storage material to improve the hydrogen storage performance of the material. Specifically, an amorphous / nanocrystalline structure is prepared by high-energy ball milling to comprehensively regulate the internal microstructure of the alloy, two additives, copper powder and CNTs, are compounded and added, and the high-energy ball milling process is used to make the two additives uniformly distributed on the surface to enhance the surface performance of the alloy, so that the surface properties of the magnesium-based hydrogen storage material are changed, and the hydrogen storage performance of Mg 85 Ni5Ce 10 is obviously improved. Experimental results show that the material can be activated after one hydrogen absorption and desorption cycle under the condition of 633K and 3.5MPa, and exhibits excellent hydrogen absorption performance under 333K-633K, especially under 333K, the hydrogen absorption amount within 1h is more than 1.8wt.%. At the same time, the material has good hydrogen desorption performance, the hydrogen desorption enthalpy is reduced to 73kJ / mol, and the activation energy of hydrogen desorption is reduced to 64.71kJ / mol. Compared with the prior art, the present application also has the following advantages:

[0019] (1) The application utilizes the characteristics that hydrogen absorption reaction usually occurs on the surface of the material, utilizes the Cu doped by the B side element to generate Mg2Cu, as a rapid diffusion channel of H, relieves the diffusion limitation of H at low temperature, effectively improves the hydrogen absorption and desorption performance of the magnesium-based alloy, meanwhile, the addition of CNTs relieves the agglomeration of Mg2Cu, shortens the diffusion distance of H in the alloy, and further improves the hydrogen absorption and desorption performance of the alloy.

[0020] (2) The application realizes the uniform doping of solid-state additives, and prepares an amorphous / nanocrystalline structure, improves the internal microstructure and surface performance of the alloy through the whole regulation idea, and simultaneously adds two additives, utilizes the complementary effect between the two and explores the best ratio of the two additives, greatly improves the hydrogen storage performance of the composite system at a lower temperature.

[0021] (3) The preparation method of the magnesium-based hydrogen storage alloy provided by the application is simple, the preparation process is simple and stable, the additive material is easy to obtain and low in price, is easy to be popularized on a large scale in industry, and the magnesium-based hydrogen storage alloy prepared is expected to become an excellent hydrogen storage alloy in the future application aspects of hydrogen storage, transportation, hydrogen fuel cell and hydrogen energy engine and the like using hydrogen as raw material. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The XRD spectrum of the magnesium-based hydrogen storage material 7A-2Cu-1CNTs prepared in Example 1 is shown in the figure;

[0023] Figure 2 The XRD spectrum of the magnesium-based hydrogen storage material A prepared in Comparative Example 2 is shown in the figure;

[0024] Figure 3 The SEM photo of the magnesium-based hydrogen storage material 7A-2Cu-1CNTs prepared in Example 1 is shown in the figure;

[0025] Figure 4 The N2 adsorption and desorption graph of the magnesium-based hydrogen storage material 7A-2Cu-1CNTs prepared in Example 1 at 77K is shown in the figure;

[0026] Figure 5 The hydrogen absorption performance of the magnesium-based hydrogen storage material 7A-3CNTs prepared in Comparative Example 2 at 633K is shown in the figure;

[0027] Figure 6 The hydrogen absorption performance of the magnesium-based hydrogen storage material 7A-2Cu-1CNTs prepared in Example 1 at 633K is shown in the figure;

[0028] Figure 7 The hydrogen absorption performance of the magnesium-based hydrogen storage material 7A-1Cu-2CNTs prepared in Example 2 at 633K is shown in the figure;

[0029] Figure 8Hydrogen absorption performance of magnesium-based hydrogen storage material 7A-3Cu prepared for Comparative Example 1 at 633K;

[0030] Figure 9 Hydrogen absorption performance of magnesium-based hydrogen storage material prepared for Examples 1-2 and Comparative Examples 1-2 at 573K and 3.5MPa;

[0031] Figure 10 Hydrogen absorption performance of magnesium-based hydrogen storage material prepared for Examples 1-2 and Comparative Examples 1-2 at 333K and 3.5MPa;

[0032] Figure 11 Hydrogen desorption performance of magnesium-based hydrogen storage material prepared for Examples 1-2 and Comparative Examples 1-2 at 573K. DETAILED DESCRIPTION

[0033] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application are described in detail below with reference to the description and examples.

[0034] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description. In other instances, well-known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present application.

[0035] Secondly, "one embodiment" or "an embodiment" as used herein means that a particular implementation can include a particular feature, structure, or characteristic, but every embodiment can not necessarily include the particular feature, structure, or characteristic. Moreover, such features, structures, or characteristics can be combined in one or more embodiments in any suitable manner. In the description of embodiments, "in one embodiment" or "in an embodiment" can refer to a particular feature, structure, or characteristic combined with one or more other particular features, structures, or characteristics.

[0036] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used are conventional materials, reagents, methods, and instruments in the art unless otherwise specified, and can be obtained by commercial channels by those skilled in the art.

[0037] Example 1:

[0038] The magnesium-based hydrogen storage alloy provided in this embodiment is Mg 85 Ni5Ce 10 The alloy powder, copper powder, and carbon nanotubes are ball milled at a mass ratio of 7:2:1 to achieve the preparation of amorphous / nanocrystalline structure and the uniform doping of the additive copper powder and carbon nanotubes, and the obtained magnesium-based hydrogen storage alloy is named 7A-2Cu-1CNTs.

[0039] The specific preparation process is as follows:

[0040] In a glove box, 0.2 g of Cu powder, 0.1 g of CNTs and 0.7 g of Mg were weighed respectively 85 Ni5Ce 10 , and placed in a 100 mL ball mill jar, which was filled with stainless steel balls with a diameter of 4-8 mm to ensure a ball-to-material ratio of 20:1, and the rotation speed was set to 350 r / min, and the ball milling time was 20 h. In order to prevent local overheating during ball milling, a forward-reverse alternating mode was adopted, and the rotation was stopped every 30 min for 30 min. The obtained sample was named 7A-2Cu-1CNTs.

[0041] Example 2:

[0042] The difference between this example and Example 1 is that the Mg 85 Ni5Ce 10 alloy powder, copper powder and carbon nanotubes were ball milled at a mass ratio of 7:1:2, and the remaining parameters and process steps were the same as in Example 1. The obtained magnesium-based hydrogen storage alloy was named 7A-1Cu-2CNTs.

[0043] Comparative Example 1:

[0044] The difference between this comparative example and Example 1 is that the Mg 85 Ni5Ce 10 alloy powder and copper powder were ball milled at a mass ratio of 7:3, and the ball milling parameter settings and process steps were the same as in Example 1. The obtained magnesium-based hydrogen storage alloy was named 7A-3Cu.

[0045] Comparative Example 2:

[0046] The difference between this comparative example and Example 1 is that the Mg 85 Ni5Ce 10 alloy powder and carbon nanotubes were ball milled at a mass ratio of 7:3, and the ball milling parameter settings and process steps were the same as in Example 1. The obtained magnesium-based hydrogen storage alloy was named 7A-3CNTs.

[0047] Comparative Example 3:

[0048] The difference between this comparative example and Example 1 is that the Mg 85 Ni5Ce 10 alloy powder was ball milled, and the ball milling parameter settings and process steps were the same as in Example 1. The obtained magnesium-based hydrogen storage alloy was named A.

[0049] Effect Example:

[0050] (1) The magnesium-based hydrogen storage alloy prepared in Example 1 and Comparative Example 3 was characterized by XRD (Bruker D8 Advance X, Cu Kα, 40 kV, 40 mA), and the results are shown in Figure 1 and Figure 2 It can be seen that the 7A-2Cu-1CNTs prepared in Example 1 has an amorphous / nanocrystalline structure, and the diffraction peak of Mg is the main one, followed by the diffraction peak of Mg2Cu and the strongest peak of Cu.

[0051] (2) The surface micro-morphology of the magnesium-based hydrogen storage alloy prepared in Example 1 was characterized by SEM (Hitachi S-4800, 10 mA, 10 kV), and the results are shown in Figure 3 It can be seen that Figure 3 Cu and CNTs are uniformly distributed on the surface of 7A-2Cu-1CNTs, and have a uniform particle size distribution, with an average particle size of 2.71 μm.

[0052] (3) The nitrogen adsorption / desorption performance of the magnesium-based hydrogen storage alloy prepared in Example 1 was characterized by ASAP2020M instrument, and the results are shown in Figure 4 It can be seen that Figure 4 7A-2Cu-1CNTs has a high specific surface area at 77 K, which is beneficial to increase the contact area with H and additives, produce more effective active sites, and thus significantly improve the activation performance and hydrogen absorption / desorption kinetics of the material.

[0053] (4) The isothermal hydrogen absorption performance of the magnesium-based hydrogen storage materials prepared in Examples 1-2 and Comparative Examples 1-2 was tested by PCT produced by Beijing Nonferrous Metals Research Institute, and the sample amount used in each test was about 0.6 g. After the sample was fully activated (i.e., reached 90% of the theoretical capacity), the test began. The sample was heated by a heating furnace with a set temperature, and the heating rate was 5 ℃ / min, and the hydrogen pressure was 3.5 MPa. The hydrogen absorption performance of the magnesium-based hydrogen storage materials prepared in Examples 1-2 and Comparative Examples 1-2 at different temperatures, and the test results are shown in Figures 5~10The test results show that 7A-3CNTs, 7A-1Cu-2CNTs and 7A-2Cu-1CNTs are activated after one hydrogen absorption and desorption cycle at 633K and 3.5MPa, which reflects the positive effect of the high specific surface area of the additive CNTs on the activation performance of the magnesium-based hydrogen storage material. In addition, 7A-3Cu, 7A-1Cu-2CNTs and 7A-2Cu-1CNTs exhibit superior hydrogen absorption kinetics at low temperature, which is due to the Mg2Cu generated by Cu doping as a rapid diffusion channel for H, which relieves the diffusion limitation of H at low temperature and effectively improves the hydrogen absorption kinetics of the hydrogen storage material at low temperature. The addition of CNTs relieves the agglomeration of nanoparticles and shortens the diffusion distance of H in the alloy, and among them, 7A-2Cu-1CNTs exhibits the best performance, which is not only activated after one hydrogen absorption and desorption cycle, but also exhibits superior hydrogen absorption performance at 333K-633K, especially at 333K, the hydrogen absorption amount within 1h is more than 1.8wt.%.

[0054] (5) The constant temperature hydrogen desorption performance of the magnesium-based hydrogen storage materials prepared in Examples 1-2 and Comparative Examples 1-2 was tested by using PCT produced by Beijing Nonferrous Metals Research Institute. The sample was fully hydrogenated, and high-pressure hydrogen was used to suppress the hydrogen desorption behavior during the sample heating process. The hydrogen absorption performance of the magnesium-based hydrogen storage materials prepared in Examples 1-2 and Comparative Examples 1-2 at 573K is shown in Table 2. Figure 11 The test results show that 7A-2Cu-1CNTs exhibits the fastest hydrogen desorption rate and the highest hydrogen desorption amount at 573K, and the hydrogen desorption performance is superior to that of single-doped 7A-3Cu and 7A-3CNTs and 7A-1Cu-2CNTs.

[0055] Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make various modifications and modifications without departing from the spirit and scope of the present application, therefore the protection scope of the present application should be defined by the claims.

Claims

1. A magnesium-based hydrogen storage material, characterized in that, Cu powder, carbon nanotube and Mg 85 Ni5Ce 10 Cu powder, carbon nanotube and Mg 85 Ni5Ce 10 Cu powder, carbon nanotube and Mg Mg 85 Ni5Ce 10 The mass ratio of the alloy powder, copper powder and carbon nanotube is 7: (1-2): (1-2); The rotation speed of the ball milling treatment is 350 r / min, the ball milling time is 20 h, and the rotation is stopped for 30 min every 30 min.

2. The magnesium-based hydrogen storage material of claim 1, wherein Mg 85 Ni5Ce 10 The mass ratio of alloy powder, copper powder and carbon nanotube is 7:2:

1.

3. The magnesium-based hydrogen storage material of claim 1, wherein Mg 85 Ni5Ce 10 The mass ratio of alloy powder, copper powder and carbon nanotube is 7:1:

2.

4. The magnesium-based hydrogen storage material of claim 1, wherein, Mg 85 Ni5Ce 10 The particle size of the alloy powder is 100-200 mesh, the particle size of the copper powder is 200 mesh, and the diameter of the carbon nanotube is 5-10 nm.

5. A method for producing the magnesium-based hydrogen storage material according to any one of claims 1 to 4, characterized in that The copper powder, carbon nanotubes and Mg 85 Ni5Ce 10 The alloy powder mixture is placed in a ball mill jar, ball-milled to obtain a magnesium-based hydrogen storage material.

6. The production method according to claim 5, wherein The rotation speed of the ball milling treatment is 350 r / min, the ball milling time is 20 h, and the rotation is stopped for 30 min every 30 min.

7. The production method according to claim 6, wherein The ball milling treatment is in a mode of alternating forward and reverse rotation.

8. The preparation method according to claim 6, characterized in that, The ball-to-material ratio of the ball milling treatment is 20:

1.

9. The preparation method according to claim 6, characterized in that, The balls used in the ball milling treatment are stainless steel balls with a diameter of 4-8 mm. The balls used in the ball milling treatment are stainless steel balls with a diameter of 4-8 mm.

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