Nanocrystalline vanadium-based hydrogen storage material as well as preparation method and application thereof

Abstract

The invention relates to the field of solid hydrogen storage, in particular to a nanocrystalline vanadium-based hydrogen storage material as well as a preparation method and application thereof. The invention provides a method for simply preparing a nanocrystalline vanadium-based hydrogen storage material by a mechanical alloying method, and the preparation method comprises the following steps: 1, crushing vanadium: carrying out vacuum heat treatment on a vanadium block, and adding hydrogen pressure at room temperature to carry out hydrogenation crushing treatment; and 2, in an inert atmosphere, carrying out mixing and ball-milling reaction with an oxide to prepare the nanocrystalline vanadium-based hydrogen storage material. The nanocrystalline vanadium-based material is directly prepared in a ball milling mode, the preparation process and operation are simple, the production period is short, energy consumption is low, and the method is suitable for large-scale production. The nanocrystalline vanadium-based material only contains vanadium and hydrogen, the reversible hydrogen storage capacity is 1.6 wt% at the temperature of 50 DEG C, the hydrogen desorption platform pressure is 6.3 bar, and the capacity retention rate is 96% after 10 times of hydrogen absorption and desorption cycles at the temperature of 30 DEG C.

Description

Technical Field

[0001] The present invention relates to the field of solid-state hydrogen storage, and particularly to a nanocrystalline vanadium-based hydrogen storage material, a preparation method thereof, and an application thereof. Background Art

[0002] Energy is the basis for ensuring human survival and a necessary factor for promoting social development. The development of human society has been accompanied by an increasing demand for energy. The large consumption of traditional fossil energy has thus triggered a serious energy crisis. Against the historical background of large-scale adjustment of the energy industry layout, hydrogen energy, as a clean, pollution-free, renewable, and efficient energy source, occupies an important position.

[0003] In recent years, two key hydrogen energy technologies, namely hydrogen production by electrolyzing water and hydrogen fuel cells, have achieved important breakthroughs. However, hydrogen storage, as an intermediate link in the hydrogen energy industry standard system, has always been unable to meet the requirements for large-scale hydrogen energy applications. There is also a large gap between domestic hydrogen storage technologies and foreign ones. Therefore, seeking safe and efficient hydrogen storage technologies has become the key to the development of the hydrogen energy industry.

[0004] Vanadium-based alloys belong to the solid-solution hydrogen storage alloys with a body-centered cubic (BCC) structure. Vanadium-based hydrogen storage alloys have a high volumetric hydrogen storage density and good kinetic properties. They have fast hydrogenation-dehydrogenation kinetics at room temperature, and the theoretical capacity reaches 3.8 wt%. However, at room temperature, due to the too low hydrogen desorption plateau pressure of its α-phase, the hydrogen desorption amount is only about half of the maximum hydrogen absorption amount. However, the reversible storage capacity of vanadium-based solid solutions is still higher than that of existing AB5-type alloys and AB2-type alloys. Composition and structure are the most important factors determining the hydrogen storage performance of hydrogen storage materials. In order to improve the hydrogen storage performance of vanadium-based solid solution hydrogen storage materials, all current methods are to change the composition of vanadium alloys to form a single-phase BCC structure or a dual-phase composite structure of BCC and C14 Laves phases [A. Mohammadi, et al., Acta Materialia. 2022, 118117], [J.M. Abdul, et al., International journal of hydrogen energy, 2016, 41(4), 2781-2787], and the vanadium-based alloys are often formed by melting during preparation. For example, when preparing and studying the hydrogen storage performance of V-Ti alloys and the microstructural changes of the alloys during hydrogen absorption, the preparation method mainly uses arc melting, and in order to avoid uneven alloy composition, multiple flips and remelting are also required. However, due to the high melting point of vanadium up to 1917 °C, even when using vanadium master alloys, melting needs to be carried out above 1500 °C, with extremely high energy consumption. In addition, during the melting process, the gas formed by vanadium volatilization is somewhat toxic and harmful to the human body. [Junko Matsudag, et al., Journal of Alloys and Compounds, 2013, 581, 369-372].

[0005] The results of a large number of experiments and theoretical calculations show that nanostructures can significantly improve the hydrogen absorption and desorption thermodynamics and kinetic properties of hydrogen storage materials [De Jongh P, et al., Chemistry of Materials, 2007, 19(24):6052–6057], [Shao H, et al., Nanotechnology, 2011, 22:235401], [Jia Y, et al., International journal of hydrogen energy, 2017, 42:22933-22941]. However, since only the melting method is used in the preparation of vanadium-based alloys at present, it is difficult to form nanostructures, resulting in the unclear influence of nanostructures on the performance of vanadium-based hydrogen storage materials and the monotonous modification strategies of vanadium-based hydrogen storage materials.

[0006] Mechanical alloying realizes the alloying of metals by means of ball milling. A large number of nanocrystalline structures can be formed during the ball milling process, thereby improving the alloy properties. The preparation method is simple and the energy consumption is low. However, due to the relatively high hardness of pure vanadium, directly ball milling vanadium powder by ball milling will result in cold welding on the wall of the ball milling tank, and this method is not suitable for the preparation of vanadium-based alloy materials. In the literature of [Vinoadh Kumar Krishnan et al., Philosophical Magazine Letters, 96(10), 402–408], Vinoadh Kumar Krishnan added stearic acid and KCl respectively when ball milling pure vanadium, and the results showed that: (1) during the ball milling process, the decomposition of stearic acid and strong mechanical deformation would trigger a mechanochemical chain reaction, resulting in a vanadium-vanadium carbide nanocomposite powder mixture; (2) ball milling vanadium powder with KCl would cause tungsten carbide contamination and produce a vanadium-tungsten carbide nanocomposite powder. Ultimately, it affects the further application of vanadium materials. In the literature of [Zhi-Yu Lu et al., Rare Metals, 40, 3195–3204], a technical solution for synthesizing vanadium flakes by liquid-phase ball milling was also provided. It was mainly to ball mill vanadium powder by adding an organic solvent heptane, and finally wash with alcohol to remove the residual organic solvent, and then vacuum dry for 12 h to obtain vanadium nanosheets. However, the liquid-phase synthesis process is relatively long and the steps are complex, making it difficult to achieve large-scale industrial application. The vanadium particles prepared by the above two methods have not confirmed their application performance in hydrogen storage materials and do not have the prospect of industrial application.

[0007] Therefore, there is currently a lack of research on the preparation of nanocrystalline materials by alloying metals with vanadium by ball milling and their hydrogen storage properties. Summary of the Invention

[0008] The present invention provides a nanocrystalline vanadium-based hydrogen storage material, a preparation method thereof and an application, so as to overcome the problems existing in the prior art that the synthesis process is relatively long, the steps are complex, and it does not have the prospect of industrial application.

[0009] To achieve the above object, the present invention provides the following specific technical solutions: A preparation method of a nanocrystalline vanadium-based hydrogen storage material, comprising the following steps:

[0010] Step 1, crushing vanadium: After vacuum heat treatment of vanadium blocks, hydrogenation and crushing treatment is carried out at room temperature under hydrogen pressure. The size of the crushed vanadium particles is 0.1-1 mm;

[0011] Step 2, mixing and ball milling reaction with an oxide to prepare a nanocrystalline vanadium-based hydrogen storage material.

[0012] Further, the mass ratio between the above vanadium particles and the oxide is 20-100:1.

[0013] Further, in the above step one, the vacuum heat treatment temperature is 500 - 600 °C, and heat preservation is carried out for 1 hour.

[0014] Further, in the above step one, the hydrogen pressure at room temperature is 50 - 100 bar, and it is maintained for 6 hours.

[0015] Further, the above vacuum heat treatment and hydrogenation treatment are repeated 3 - 5 times.

[0016] Further, in the above step two, the ball milling reaction is carried out in an inert atmosphere or a vacuum environment at room temperature.

[0017] Further, the above ball milling reaction uses a planetary ball mill, stainless steel balls are used, the mass ratio of balls to materials is 30 - 100:1, the ball milling rotation speed is 200 - 300 revolutions per minute, and the ball milling time is 1 - 6 hours.

[0018] Further, the above oxide is cerium oxide or aluminum oxide.

[0019] Further, the nanocrystalline vanadium - based hydrogen storage material prepared by the above preparation method.

[0020] Further, the application of the above - mentioned nanocrystalline vanadium - based hydrogen storage material in hydrogen solid - state storage for fuel cell hydrogen supply, hydrogen compression system, hydrogen storage tank in hydrogen filling station or distributed energy hydrogen storage tank.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The present invention first provides a simple idea of obtaining vanadium nanocrystalline materials through mechanical alloying. From the perspective of raw materials, commercially available pure vanadium powder is easily oxidized. Therefore, during the preparation of the hydrogen storage material, vanadium blocks are selected for hydrogenation and crushing treatment. Secondly, a suitable oxide is selected as a grinding aid to prevent cold welding of vanadium particles during ball milling. The metal oxides selected as grinding aids are cerium oxide and aluminum oxide. The reason for choosing these two substances is that they themselves have relatively high hardness, which can effectively achieve nanocrystallization of the vanadium - based hydrogen storage material grains, and at the same time break the passivation layer on the surface of the vanadium - based hydrogen storage material, improving the activation performance and hydrogen absorption and desorption kinetic performance of the hydrogen storage material. Finally, the hydrogenation reaction and ball milling reaction of the present invention are both carried out at room temperature, with mild conditions and low energy consumption.

[0023] 2. The present invention adopts the mechanical alloying method, avoiding the disadvantages brought by the relatively complex and energy - consuming preparation method of melting. The nanocrystalline vanadium - based material directly prepared through the designed ball milling method only contains vanadium hydride and no other impurities. Its reversible hydrogen storage capacity at 50 °C is 1.6 wt%, the hydrogen desorption platform pressure is 6.3 bar, and the capacity retention rate after 10 hydrogen absorption and desorption cycles at 30 °C is 96%. And its hydrogen storage performance is tested, improving the kinetic performance of the vanadium - based hydrogen storage material.

[0024] 3. The preparation process of the present invention is simple, easy to operate, has a short production cycle, low energy consumption, and is suitable for large-scale industrial production. It provides new ideas for the application and research of vanadium-based hydrogen storage materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the X-ray diffraction pattern of the ball-milled product prepared in Example 1 of the present invention, and the standard XRD diffraction PDF card of VH 0.81 is given;

[0026] Figure 2 It is the SEM morphology diagram of the ball-milled product prepared in Example 1 of the present invention;

[0027] Figure 3 It is the hydrogen desorption PCT curve of the ball-milled product prepared in Example 1 of the present invention at 50 °C;

[0028] Figure 4 It is the isothermal hydrogen absorption kinetic curve of the ball-milled product prepared in Example 1 of the present invention at 30 °C, 50 °C, 80 °C, and 100 °C;

[0029] Figure 5 It is the high-resolution transmission electron microscope image (HRTEM) of the ball-milled product prepared in Example 1 of the present invention, its corresponding electron diffraction pattern, and the energy spectrum diagram (EDS) of the corresponding elements;

[0030] Figure 6 It is the hydrogen desorption PCT curve at 30 °C before and after 10 cycles in Example 1 of the present invention;

[0031] Figure 7 It is the X-ray diffraction pattern of the ball-milled product prepared in Example 2 of the present invention;

[0032] Figure 8 It is the SEM morphology diagram of the ball-milled product prepared in Example 2 of the present invention;

[0033] Figure 9 It is the hydrogen desorption PCT curve of the ball-milled product prepared in Example 2 of the present invention at 50 °C;

[0034] Figure 10 It is the high-resolution transmission electron microscope image (HRTEM) of the ball-milled product prepared in Example 2 of the present invention, its corresponding electron diffraction pattern, and the energy spectrum diagram (EDS) of the corresponding elements;

[0035] Figure 11 It is the X-ray diffraction pattern of the ball-milled product prepared in Example 3 of the present invention;

[0036] Figure 12The PCT curve of hydrogen desorption at 50 °C for the ball-milled product prepared in Example 3 of the present invention;

[0037] Figure 13 The X-ray diffraction pattern of the ball-milled product prepared in Comparative Example 2 of the present invention;

[0038] Figure 14 The PCT curve of hydrogen desorption at 50 °C for the ball-milled product prepared in Comparative Example 2 of the present invention. Detailed implementation manners

[0039] The present invention will be described in detail below with reference to the accompanying drawings and examples.

[0040] Example 1, a preparation method of a nanocrystalline vanadium-based hydrogen storage material, comprising the following steps:

[0041] Step 1: Inside a glove box filled with high-purity argon, load vanadium blocks onto a hydrogen sorption-desorption instrument, heat to 500 °C under vacuum conditions and hold for 1 h for heat treatment, cool to room temperature and then charge 60 bar hydrogen pressure and hold for 6 h for hydrogenation treatment. The above operations are repeated 4 times to obtain crushed vanadium particles, and the size of the crushed vanadium particles is 0.1 - 1 mm.

[0042] Step 2: In a glove box under an argon atmosphere, mix the crushed vanadium particles and cerium oxide in a mass ratio of 50:1, place them in a stainless steel ball milling tank of a planetary ball mill and seal it. Use stainless steel grinding balls, with a ball-to-material mass ratio of 50:1 and a ball milling speed of 300 revolutions per minute. After ball milling for 3 h, a nanocrystalline vanadium-based hydrogen storage material is obtained.

[0043] See Figure 1 , only a nanocrystalline vanadium-based hydrogen storage material with the main component of VH 0.81 is observed in the product, without other impurities.

[0044] See Figure 2 , through the SEM morphology diagram of the ball-milled product, it can be seen that the sample presents irregular granular shape;

[0045] See Figure 3 , through the PCT curve of hydrogen desorption at 50 °C for the ball-milled product, it can be seen that its reversible hydrogen desorption capacity is 1.6 wt%, and the hydrogen desorption plateau pressure is 6.3 bar. The hydrogen storage capacity is higher than that of traditional rare earth-based hydrogen storage alloys, and the relatively high hydrogen desorption plateau pressure makes it suitable for supplying hydrogen for fuel cells and for applications in hydrogen solid storage fields such as hydrogen compression systems, hydrogen storage tanks at hydrogen refueling stations, and distributed energy hydrogen storage tanks.

[0046] See Figure 4, from the isothermal hydrogen absorption kinetic curves of the ball-milled product at 30 °C, 50 °C, 80 °C, and 100 °C respectively, it can be seen that the maximum hydrogen storage capacity of the nanocrystalline vanadium-based hydrogen storage material reaches 2.53 wt% after 2500 s at 30 °C. Combining with Figure 3 the reversible hydrogen desorption capacity, the effective reversibility rate of the nanocrystalline vanadium-based hydrogen storage material is 63%; the nanocrystalline vanadium-based hydrogen storage material can reach hydrogen absorption saturation in 80 s at 100 °C, showing excellent hydrogen absorption kinetics.

[0047] See Figure 5 , lattice fringes with interplanar spacings of 0.226 nm and 0.215 nm were observed from the TEM images, corresponding to the (101) plane and (110) plane of VH 0.81 respectively, and the size of a single vanadium nanocrystal is about 10 nm, and the electron diffraction pattern shows typical nano-polycrystalline characteristics; it can be seen from the EDS that the elemental distributions of vanadium and cerium are uniform without elemental segregation.

[0048] See Figure 6 , from the hydrogen desorption PCT curve of the ball-milled product at 30 °C before and after 10 cycles, it can be seen that the capacity retention rate reaches 96%, indicating that the nanocrystalline vanadium-based hydrogen storage material has good hydrogen absorption and desorption cycling performance.

[0049] Example 2

[0050] The difference between this example and Example 1 is that: the grinding aid used is alumina, and the nanocrystalline vanadium-based hydrogen storage material is obtained after ball milling for 6 h.

[0051] See Figure 7 , only the vanadium-based hydrogen storage material with the main component of VH 0.81 was still observed in the product without other impurities.

[0052] See Figure 8 , from the SEM morphology image of the ball-milled product, it can be seen that the sample presents irregular granular shape;

[0053] See Figure 9 , from the hydrogen desorption PCT curve of the ball-milled product at 50 °C, it can be seen that its reversible hydrogen desorption capacity is 1.29 wt% and the hydrogen desorption plateau pressure is 6.2 bar.

[0054] See Figure 10 , it can be seen from the TEM image that the size of vanadium nanocrystals is about 11 nm, and the electron diffraction pattern shows typical nano-polycrystalline characteristics; it can be seen from the EDS that the elemental distributions of vanadium and cerium are uniform without elemental segregation.

[0055] Example 3

[0056] The difference between this embodiment and Embodiment 1 is that the crushed vanadium particles and cerium oxide are ball-milled at a mass ratio of 100:1.

[0057] See Figure 11 , and only vanadium hydrogen storage materials with VH as the main component are observed in the product, without any other impurities. 0.81 .

[0058] See Figure 12 , through the PCT hydrogen desorption curve of the ball-milled product at 50 °C, it can be seen that its reversible hydrogen desorption capacity is 0.96 wt%, and the hydrogen desorption plateau pressure is 6.4 bar.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Embodiment 1 is that no grinding aid is added during the mixed ball milling. It is found that without adding any grinding aid, the sample will cold-weld to the ball milling wall after ball milling, and the sample cannot be obtained.

[0061] Comparative Example 2

[0062] Step 1: Inside a glove box filled with high-purity argon, load the vanadium block onto a hydrogen sorption instrument, heat it to 500 °C under vacuum conditions and hold for 1 h, cool it to room temperature, and then charge it with a hydrogen pressure of 60 bar and hold for 6 h. The above operations are repeated 4 times to obtain crushed vanadium particles.

[0063] Step 2: In a glove box under an argon atmosphere, mix the crushed vanadium particles with the organic solvent acetone and place them in a stainless steel ball milling jar for sealing. Add acetone drop by drop, with a total of 1 mL added. Use stainless steel grinding balls, with a ball-to-material ratio of 50:1 and a ball milling speed of 300 revolutions per minute. After ball milling for 3 h, collect the sample. Subsequently, add acetone solvent for centrifugation at a speed of 5000 r and a centrifugation time of 6 min. After centrifugation, collect the solid sample and perform vacuum solvent removal treatment at room temperature in a tube furnace. After 6 h of vacuum treatment, a powder sample is obtained.

[0064] See Figure 13 , it can be seen that the main component of the sample obtained by ball milling with acetone addition is still VH 0.81 .

[0065] See Figure 14 , through the PCT hydrogen desorption curve of the ball-milled product at 50 °C, it can be seen that it has almost no reversible hydrogen storage capacity and therefore cannot be used as a hydrogen storage material.

[0066] The above description is an illustration of the specific implementation of the present invention, rather than a limitation to the present invention. Those skilled in the relevant technical field can also make various equivalent technical solutions without departing from the scope of the present invention. Therefore, all equivalent technical solutions should be included in the protection scope of the present invention.

Claims

1. A preparation method of a nanocrystalline vanadium-based hydrogen storage material, characterized in that, It includes the following steps: Step 1, crushing vanadium: After subjecting vanadium blocks to vacuum heat treatment, hydrogenation and crushing treatment is carried out by adding hydrogen pressure at room temperature. The size of the crushed vanadium particles is 0.1 - 1 mm; Step 2, mixing and ball-milling reaction with an oxide to prepare a nanocrystalline vanadium-based hydrogen storage material.

2. The preparation method of a nanocrystalline vanadium-based hydrogen storage material according to claim 1, characterized in that, The mass ratio between the vanadium particles and the oxide is 20 - 100:

1.

3. The preparation method of a nanocrystalline vanadium-based hydrogen storage material according to claim 2, characterized in that, In Step 2, in Step 1, the vacuum heat treatment temperature is 500 - 600 °C and the heat preservation time is 1 hour.

4. The preparation method of a nanocrystalline vanadium-based hydrogen storage material according to claim 2, characterized in that, In Step 1, the hydrogen pressure at room temperature is 50 - 100 bar and it is maintained for 6 hours.

5. The preparation method of a nanocrystalline vanadium-based hydrogen storage material according to claim 3 or 4, characterized in that, The vacuum heat treatment and hydrogenation treatment are repeated 3 - 5 times.

6. The preparation method of a nanocrystalline vanadium-based hydrogen storage material according to claim 5, characterized in that, In Step 2, the ball-milling reaction is carried out in an inert atmosphere or a vacuum environment at room temperature.

7. The preparation method of a nanocrystalline vanadium-based hydrogen storage material according to claim 6, characterized in that, The ball-milling reaction uses a planetary ball mill, stainless steel balls are used, the ball-to-material mass ratio is 30 - 100:1, the ball-milling rotation speed is 200 - 300 revolutions per minute, and the ball-milling time is 1 - 6 hours.

8. The preparation method of a nanocrystalline vanadium-based hydrogen storage material according to claim 6, characterized in that, The oxide is cerium oxide or aluminum oxide.

9. A nanocrystalline vanadium-based hydrogen storage material prepared by the preparation method according to claim 1.

10. Application of a nanocrystalline vanadium-based hydrogen storage material according to claim 8 in aspects of hydrogen solid-state storage in fuel cell hydrogen supply, hydrogen compression systems, hydrogen storage tanks in hydrogen refueling stations or distributed energy hydrogen storage tanks.

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