A magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification and its preparation method

Abstract

The present invention relates to a magnesium-based hydrogen storage material based on the synergistic modification of a VTiFe solid solution and CNTs and a preparation method thereof, belonging to the technical field of the preparation of magnesium-based hydrogen storage materials. The present invention, through the synergistic modification of a VTiFe solid solution and CNTs, has the following advantages: (1) stable hydrogen storage cycle kinetics, with the hydrogen storage capacity remaining above 98.8% after 31 hydrogen absorption and desorption cycles; (2) increased hydrogen release capacity and improved hydrogen release rate; and (3) improved hydrogen absorption rate and increased hydrogen absorption capacity.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of magnesium-based hydrogen storage materials, and relates to a magnesium-based hydrogen storage material based on synergistic modification of VTiFe solid solution and CNTs and a preparation method thereof. Background Art

[0002] Hydrogen energy has the characteristics of abundant resources, carbon-free, high energy density (120MJ / kg), and diverse application scenarios. It has great potential in reducing environmental pollution and promoting energy transformation, and has therefore become a global development strategy and focus of competition.

[0003] At present, safe and efficient hydrogen storage and transportation technology is one of the main bottlenecks restricting the development of the hydrogen energy industry chain.

[0004] Compared with traditional hydrogen storage technologies, magnesium-based solid-state hydrogen storage technologies offer advantages such as low cost, high hydrogen storage density (7.6 wt.% and 110 g H2 / L), safety, high efficiency, and good reversibility, opening up greater possibilities for the large-scale utilization of hydrogen energy. However, inherent thermodynamic and kinetic challenges of MgH2 remain, directly leading to its high absorption and desorption temperatures (>350°C) and slow reaction rates. Addressing these issues remains a major scientific challenge for the widespread application of magnesium-based solid-state hydrogen storage technologies.

[0005] Adding catalysts is one of the simplest and most effective ways to improve the hydrogen storage performance of MgH2. Alloy catalysts based on transition metals can provide more active sites and diffusion channels for hydrogen dissociation and transfer, and through multi-component synergistic effects, they exhibit excellent catalytic effects on the hydrogen absorption and desorption reactions of MgH2. Therefore, it is necessary to study new magnesium-based hydrogen storage materials to address the shortcomings of existing magnesium-based hydrogen storage materials. Summary of the Invention

[0006] In view of this, one of the objects of the present invention is to provide a magnesium-based hydrogen storage material based on the synergistic modification of VTiFe solid solution and CNTs; a second object of the present invention is to provide a preparation method of a magnesium-based hydrogen storage material based on the synergistic modification of VTiFe solid solution and CNTs; a third object of the present invention is to provide an application of a magnesium-based hydrogen storage material based on the synergistic modification of VTiFe solid solution and CNTs in solid-state hydrogen storage.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] 1. A magnesium-based hydrogen storage material based on the synergistic modification of VTiFe solid solution and CNTs and a preparation method thereof, wherein the magnesium-based hydrogen storage material comprises VTiFe solid solution, CNTs and MgH2;

[0009] The structural formula of the VTiFe solid solution is V xTi y Fe z , where 0.1≤x≤0.5, 0.1≤y≤0.5, 0.1≤z≤0.5.

[0010] Preferably, in terms of mass percentage, the VTiFe solid solution in the magnesium-based hydrogen storage material is 0.1 wt.% to 20 wt.%, and the CNTs is 0.1 wt.% to 10 wt.%.

[0011] Preferably, in terms of mass percentage, the VTiFe solid solution in the magnesium-based hydrogen storage material is 2 wt.% to 15 wt.%, and the CNTs is 1 wt.% to 5 wt.%.

[0012] Preferably, in terms of mass percentage, the VTiFe solid solution in the magnesium-based hydrogen storage material is 3 wt.% to 10 wt.%, and the CNTs is 2.5 wt.% to 3.5 wt.%.

[0013] 2. A method for preparing the above-mentioned magnesium-based hydrogen storage material, the method comprising the following steps:

[0014] (1) Preparation of VTiFe solid solution: 99% purity of metal elements vanadium (V), titanium (Ti) and iron (Fe) were mixed, wet ball milled, and vacuum dried to obtain VTiFe solid solution;

[0015] (2) preparing a MgH2-VTiFe composite material: mixing the VTiFe solid solution and MgH2 powder, and performing mechanical ball milling to prepare a MgH2-VTiFe composite material;

[0016] (3) Preparation of magnesium-based hydrogen storage material: The MgH2-VTiFe composite material and CNTs are mixed and mechanically ball milled to obtain a magnesium-based hydrogen storage material based on the synergistic modification of VTiFe solid solution and CNTs.

[0017] Preferably, in step (1), the milling jar and milling balls used in the wet ball milling are made of stainless steel balls, argon is used as the ball milling atmosphere, and n-heptane or anhydrous ethanol is used as the ball milling process control agent.

[0018] Preferably, in step (1), the wet ball milling time is 10 to 40 hours, the ball milling speed is 300 rpm to 500 rpm, and the ball-to-material ratio is 5:1 to 30:1;

[0019] In step (1), the vacuum drying is carried out in a vacuum drying oven at 70° C. to 100° C. for 2 to 10 hours.

[0020] Preferably, in step (2), the mechanical ball mill uses stainless steel balls, argon as the ball milling atmosphere, a ball-to-material ratio of 10:1 to 50:1, a ball milling time of 5 to 10 hours, and a ball milling speed of 350 rpm to 500 rpm.

[0021] Preferably, in step (3), the mechanical ball mill uses stainless steel balls, argon as the ball milling atmosphere, a ball-to-material ratio of 10:1 to 50:1, a ball milling time of 2 to 5 hours, and a ball milling speed of 350 rpm to 500 rpm.

[0022] 3. Application of the above-mentioned magnesium-based hydrogen storage materials in solid-state hydrogen storage.

[0023] The beneficial effects of the present invention are:

[0024] 1. The present invention discloses a magnesium-based hydrogen storage material based on the synergistic modification of VTiFe solid solution and CNTs. On the one hand, the VTiFe solid solution is used as a catalyst and has a single-phase face-centered cubic crystal structure. After composite ball milling with MgH2, it can be uniformly dispersed on the surface of the MgH2 matrix, and nano-α-Fe particles are precipitated in situ. It can cooperate with VTiFe catalysis to provide a large number of active sites for hydrogen dissociation and diffusion, and effectively hinder the growth of grains during the cyclic hydrogen absorption and desorption process, promoting the stable and efficient hydrogen storage dynamics of MgH2. On the other hand, CNTs are used as surface modification materials. During the ball milling process, they are broken into nano-thin films and adhere to the surface of MgH2 particles, effectively suppressing the agglomeration of particles during the cycle and greatly improving the cyclic stability of MgH2. Therefore, MgH2 modified by VTiFe solid solution and CNTs has the following advantages: (1) stable hydrogen storage cycle kinetics, and the hydrogen storage capacity can still be maintained at more than 98.8% after 31 cycles of hydrogen absorption and desorption; (2) increased hydrogen release capacity and improved hydrogen release rate (at 300°C, the magnesium-based hydrogen storage material formed by VTiFe solid solution and CNTs modified MgH2 releases 5.8wt.% of hydrogen in just 5 minutes, while pure MgH2 can only release 3.4wt.% of hydrogen in 10 minutes at the same temperature, and the hydrogen release capacity has increased by 36%); (3) increased hydrogen absorption capacity (by adding 6wt.% VTiFe solid solution and 3wt.% CNTs, MgH2 can quickly absorb 5.6wt.% of hydrogen in 10 minutes at 175°C, while pure MgH2 can only absorb 1.6wt.% of hydrogen in 10 minutes at the same temperature. Even at 75°C, it can absorb 2.2wt.% of hydrogen in 30 minutes).

[0025] 2. The present invention also discloses a method for preparing a magnesium-based hydrogen storage material based on the synergistic modification of a VTiFe solid solution and CNTs. The method involves first mixing elemental vanadium (V), elemental titanium (Ti), and elemental iron (Fe) and then wet-milling the VTiFe solid solution. The solution is then mixed with MgH2 powder and mechanically milled to produce a MgH2-VTiFe composite material. Finally, the material is further mixed with CNTs and mechanically milled. The method is simple and easy to operate, meeting the requirements for industrial application of magnesium-based hydrogen storage materials.

[0026] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0028] Figure 1 This is an SEM image of the VTiFe solid solution prepared in Example 1;

[0029] Figure 2 The XRD pattern of the VTiFe solid solution prepared in Example 1;

[0030] Figure 3 This is an SEM image of the magnesium-based hydrogen storage material synergistically modified with VTiFe solid solution and CNTs prepared in Example 1;

[0031] Figure 4 The temperature-dependent hydrogen release curve (TPD) and the corresponding differential curves (Differential curves) of the magnesium-based hydrogen storage material (MgH2-VTiFe-CNTs mixed powder) prepared in Example 1;

[0032] Figure 5 The isothermal hydrogen desorption curves of the ball-milled MgH2 powder and the magnesium-based hydrogen storage material (MgH2-VTiFe-CNTs mixed powder) prepared in Example 1 are shown;

[0033] Figure 6 Isothermal hydrogen absorption curves of ball-milled MgH2 powder and magnesium-based hydrogen storage material (MgH2-VTiFe-CNTs mixed powder) prepared in Example 1;

[0034] Figure 7This is a diagram of the cyclic hydrogen absorption and desorption performance of the magnesium-based hydrogen storage material (MgH2-VTiFe-CNTs mixed powder) prepared in Example 1. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0036] Example 1

[0037] A magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification, the specific preparation method is as follows:

[0038] (1) Preparation of VTiFe solid solution: The VTiFe solid solution catalyst was prepared by wet ball milling. In a glove box filled with argon, 1.625 g of vanadium (V), 0.68 g of elemental titanium (Ti), and 2.695 g of elemental iron (Fe) powder were weighed and placed in a 100 mL stainless steel ball mill (the total mass of the three powders was 5 g). 15 mL of n-heptane was added as a process control agent to prevent cold welding of the powders during the ball milling process. 50 g of stainless steel grinding balls with a diameter of 8 mm were added according to a mass ratio of 10:1. A planetary ball mill was used to mill the mixture at a speed of 350 rpm for 30 h under an argon atmosphere. The milling was performed in a forward and reverse alternating manner. The milling was stopped for 5 min after every 20 min of ball milling. Finally, the VTiFe solid solution (VTiFe) was obtained after drying at 80 °C for 10 h in a vacuum drying oven. 0.48 Ti 0.2 Fe 0.32 ).

[0039] (2) Preparation of MgH2-V 0.48 Ti 0.2 Fe 0.32 Composite material: 0.12g of the prepared V 0.48 Ti 0.2 Fe 0.32 The solid solution was used as a catalyst and mixed with 1.82 g of MgH2 powder under high purity argon atmosphere (where V 0.48 Ti 0.2 Fe 0.32 The mass ratio of solid solution to MgH2 powder was 6:91), and MgH2-V was prepared by mechanical ball milling for 8 h under argon atmosphere.0.48 Ti 0.2 Fe 0.32 Mix the powder (wherein the ball-to-material ratio is 30:1, the ball mill speed is 400 rpm, the ball mill jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm).

[0040] (3) Preparation of magnesium-based hydrogen storage material: 0.06 g of CNTs powder was mixed with 1.94 g of the MgH2-V prepared above. 0.48 Ti 0.2 Fe 0.32 The mixed powders (CNTs and MgH2-V 0.48 Ti 0.2 Fe 0.32 The mass ratio of the mixed powder was 3:97), and the magnesium-based hydrogen storage material (MgH2-6 wt.% VTiFe solid solution and CNTs synergistically modified) was prepared by mechanical ball milling for 4 h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32 -3wt.% CNTs mixed powder), wherein the ball-to-material ratio during ball milling is 30:1, the ball milling speed is 400 rpm, the ball milling jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm.

[0041] Figure 1 This is the SEM image of the VTiFe solid solution prepared in Example 1. Figure 1 It can be seen that the VTiFe solid solution (V 0.48 Ti 0.2 Fe 0.32 Solid solution) is a powdery particle of 0.3μm to 10μm.

[0042] Figure 2 V prepared in Example 1 0.48 Ti 0.2 Fe 0.32 XRD pattern of solid solution. Figure 2 It can be seen that the VTiFe solid solution has a single-phase face-centered cubic structure.

[0043] Figure 3 V prepared in Example 1 0.48 Ti 0.2 Fe 0.32 SEM images of magnesium-based hydrogen storage materials modified by solid solution and CNTs. Figure 3 It can be seen that the VTiFe solid solution (V 0.48 Ti 0.2 Fe 0.32The particle size of the Mg-based hydrogen storage material synergistically modified with solid solution) and CNTs is 0.2 to 5 μm.

[0044] The V prepared in Study Example 1 0.48 Ti 0.2 Fe 0.32 e solid solution and magnesium-based hydrogen storage materials (MgH2-6 wt.% V 0.48 Ti 0.2 Fe 0.32 -3wt.%CNTs mixed powder) are as follows:

[0045] 50 mg of the VTiFe solid solution and the magnesium-based hydrogen storage material (MgH2-6 wt.% V 0.48 Ti 0.2 Fe 0.32 -3wt.% CNTs mixed powder), the temperature-dependent hydrogen desorption curve of the sample was tested using a PCTpro model high-pressure gas adsorption instrument: isothermal hydrogen desorption curves at 250℃ and 300℃ under an initial hydrogen pressure of 0.01MPa; isothermal hydrogen absorption curves at 75℃, 125℃ and 175℃ under an initial hydrogen pressure of 3MPa; and 31-cycle hydrogen absorption and desorption curves at 300℃.

[0046] Figure 4 The magnesium-based hydrogen storage material (MgH2-6 wt.% V 0.48 Ti 0.2 Fe 0.32 -3wt.% CNTs mixed powder) temperature-dependent hydrogen release curve (TPD) and corresponding differential curves. Figure 4 It can be seen that the magnesium-based hydrogen storage material (MgH2-6 wt.% V 0.48 Ti 0.2 Fe 0.32 -3wt.% CNTs mixed powder) began to release hydrogen at 176℃, and the peak hydrogen release temperature was 245℃.

[0047] In order to compare the magnesium-based hydrogen storage material (MgH2-6 wt.% V 0.48 Ti 0.2 Fe 0.32 -3wt.% CNTs mixed powder), and ball-milled MgH2 powder (2g commercial MgH2 was ball-milled for 12h in a high-purity argon atmosphere to prepare the ball-milled MgH2 powder, wherein the ball-to-material ratio was 30:1, the rotation speed was 400rpm, the ball milling jar used was a stainless steel jar with a volume of 100mL, and the grinding balls were stainless steel grinding balls with diameters of 8mm and 6mm) as the control group. Figure 5The ball-milled MgH2 powder and the magnesium-based hydrogen storage material (MgH2-6 wt.% V 0.48 Ti 0.2 Fe 0.32 -3wt.%CNTs) isothermal hydrogen release curve. Figure 5 It can be seen that the magnesium-based hydrogen storage material (MgH2-6 wt.% V 0.48 Ti 0.2 Fe 0.32 -3wt.% CNTs mixed powder) can release 5.5wt.% hydrogen at 250℃ for 10min; at 300℃, V 0.48 Ti 0.2 Fe 0.32 The solid solution and CNTs modified MgH2 release 5.8wt.% hydrogen in just 5 minutes, while the ball-milled MgH2 powder can only release 3.4wt.% hydrogen in 10 minutes at the same temperature. The magnesium-based hydrogen storage material (MgH2-6wt.%V 0.48 Ti 0.2 Fe 0.32 -3wt.%CNTs) increased by 36%. 0.48 Ti 0.2 Fe 0.32 Mg-based hydrogen storage materials (MgH2-6 wt.%V) modified by solid solution and CNTs 0.48 Ti 0.2 Fe 0.32 -3wt.% CNTs) not only has a lower initial hydrogen desorption temperature, but also has significantly improved hydrogen desorption kinetics.

[0048] Figure 6 The ball-milled MgH2 powder and the magnesium-based hydrogen storage material (MgH2-6 wt.% V 0.48 Ti 0.2 Fe 0.32 -3wt.%CNTs mixed powder) isothermal hydrogen absorption curve. Figure 6 It can be seen that the magnesium-based hydrogen storage material (MgH2-6 wt.% V 0.48 Ti 0.2 Fe 0.32 -3wt.% CNTs) can quickly absorb 5.6wt.% of hydrogen within 10min at 175℃, and even 2.2wt.% and 5.0wt.% of hydrogen within 30min at 75℃ and 125℃ respectively, while ball-milled MgH2 can only absorb 1.6wt.% of hydrogen within 10min at 175℃. It can be concluded that the magnesium-based hydrogen storage material (MgH2-6 wt.% V0.48 Ti 0.2 Fe 0.32 -3wt.% CNTs mixed powder) was significantly improved in hydrogen absorption kinetics.

[0049] Figure 7 The magnesium-based hydrogen storage material (MgH2-6 wt.% V 0.48 Ti 0.2 Fe 0.32 -3wt.%CNTs mixed powder) cyclic hydrogen absorption and desorption performance diagram. Figure 7 It can be seen that after 31 cycles of hydrogen absorption and desorption, the hydrogen desorption amount of MgH2 modified by VTiFe solid solution and CNTs is still 5.85wt.%, which is only 0.07wt.% lost compared with the first hydrogen desorption, and the capacity retention rate is 98.8%, showing stable cycle reversibility.

[0050] Example 2

[0051] The “1.625 g of vanadium (V), 0.68 g of elemental titanium (Ti) and 2.695 g of elemental iron (Fe) powder” in step (1) of Example 1 were modified to “0.488 g of vanadium (V), 1.839 g of elemental titanium (Ti) and 2.673 g of elemental iron (Fe) powder” and “2.022 g of vanadium (V), 2.372 g of elemental titanium (Ti) and 0.606 g of elemental iron (Fe) powder” and 2.297 g of vanadium (V), 0.432 g of elemental titanium (Ti) and 2.021 g of elemental iron (Fe) powder, respectively. The remaining preparation conditions were the same as those in step (1) of Example 1, thereby obtaining V, ... 0.1 Ti 0.4 Fe 0.5 Solid solution, V 0.4 Ti 0.5 Fe 0.1 Solid solution and V 0.5 Ti 0.1 Fe 0.4 Solid solution prepared magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification.

[0052] (2) Replace the "V" in step (2) of Example 1 0.48 Ti 0.2 Fe 0.32 Solid solution" was changed to V 0.1 Ti 0.1 Fe 0.5 Solid solution, V 0.4 Ti 0.5 Fe 0.1 Solid solution and V 0.5 Ti 0.1 Fe0.4 Solid solution, the rest of the preparation conditions are the same as step (2) of Example 1, and MgH2-V 0.1 Ti 0.1 Fe 0.5 Composite materials, MgH2-V 0.4 Ti 0.5 Fe 0.1 Composite materials and MgH2-V 0.5 Ti 0.1 Fe 0.4 Composite materials.

[0053] (3) The "MgH2-V 0.48 Ti 0.2 Fe 0.32 ” were modified to MgH2-V 0.1 Ti 0.1 Fe 0.5 Composite materials, MgH2-V 0.4 Ti 0.5 Fe 0.1 Composite materials and MgH2-V 0.5 Ti 0.1 Fe 0.4 The rest of the preparation conditions were the same as those in Example 1 (3), thereby obtaining a magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification, and obtaining MgH2-6 wt.% V 0.1 Ti 0.1 Fe 0.5 -3wt.%CNTs mixed powder, MgH2-6 wt.%V 0.4 Ti 0.5 Fe 0.1 -3wt.% CNTs mixed powder and MgH2-6 wt.% V 0.5 Ti 0.1 Fe 0.4 -3wt.% CNTs mixed powder).

[0054] Table 1 is a performance comparison table of four magnesium-based hydrogen storage materials based on VTiFe solid solution and CNTs synergistic modification and ball-milled MgH2 powder obtained in Example 1 and Example 2 in terms of initial dehydrogenation temperature, hydrogen release amount at 300°C for 5 minutes, and hydrogen absorption amount at 175°C for 10 minutes. It can be seen from Table 1 that compared with ball-milled MgH2 powder, the magnesium-based hydrogen storage materials prepared by the present invention and synergistically modified with VTiFe solid solution and CNTs have significantly improved performance in terms of initial dehydrogenation temperature, hydrogen release amount at 300°C for 5 minutes, and hydrogen absorption amount at 175°C for 10 minutes. Among them, MgH2-6 wt.% V 0.48 Ti 0.2 Fe0.32 -3wt.%CNTs composite material showed the best hydrogen storage performance. In the present invention, the VTiFe solid solution and CNTs synergistically modified MgH2 powder can indeed improve the corresponding performance. The structural formula of VTiFe solid solution is V x Ti y Fe z , where 0.1≤x≤0.5, 0.1≤y≤0.5, 0.1≤z≤0.5.

[0055] Table 1 Performance comparison of different magnesium-based hydrogen storage materials and ball-milled MgH2 powder

[0056]

[0057] Example 3

[0058] A magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification, the specific preparation method is as follows:

[0059] (1) Preparation of VTiFe solid solution: The VTiFe solid solution catalyst was prepared by wet ball milling. In a glove box filled with argon, 1.625 g of vanadium (V), 0.68 g of elemental titanium (Ti), and 2.695 g of elemental iron (Fe) powder were weighed and placed in a 100 mL stainless steel ball mill (the total mass of the three powders was 5 g). 15 mL of n-heptane was added as a process control agent to prevent cold welding of the powders during the ball milling process. 50 g of stainless steel grinding balls with a diameter of 8 mm were added according to a mass ratio of 10:1. A planetary ball mill was used to mill the mixture at a speed of 350 rpm for 30 h under an argon atmosphere. The milling was performed in a forward and reverse alternating manner. The milling was stopped for 5 min after every 20 min of ball milling. Finally, the VTiFe solid solution (VTiFe) was obtained after drying at 80 °C for 10 h in a vacuum drying oven. 0.48 Ti 0.2 Fe 0.32 ).

[0060] (2) Preparation of MgH2-VTiFe composite material: 0.002g of the prepared V 0.48 Ti 0.2 Fe 0.32 The solid solution was used as a catalyst and mixed with 1.798 g of MgH2 powder under high purity argon atmosphere (V 0.48 Ti 0.2 Fe 0.32 The mass ratio of solid solution to MgH2 powder was 1:89.9), and MgH2-V was prepared by mechanical ball milling for 8 h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32Mix the powder (wherein the ball-to-material ratio is 30:1, the ball mill speed is 400 rpm, the ball mill jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm).

[0061] (3) Preparation of magnesium-based hydrogen storage material: 0.2 g of CNTs powder was mixed with 1.8 g of the MgH2-VTiFe mixed powder prepared above under a high-purity argon atmosphere (where CNTs and MgH2-V 0.48 Ti 0.2 Fe 0.32 The mass ratio of the mixed powder was 1:9), and the magnesium-based hydrogen storage material (MgH2-0.1wt.%VTiFe solid solution and CNTs synergistically modified) was prepared by mechanical ball milling for 4h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32 -10wt.% CNTs mixed powder), wherein the ball-to-material ratio during ball milling is 30:1, the ball milling speed is 400rpm, the ball milling jar is a 100mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8mm and 6mm.

[0062] Example 4

[0063] A magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification, the specific preparation method is as follows:

[0064] (1) Preparation of VTiFe solid solution: The VTiFe solid solution catalyst was prepared by wet ball milling. In a glove box filled with argon, 1.625 g of vanadium (V), 0.68 g of elemental titanium (Ti), and 2.695 g of elemental iron (Fe) powder were weighed and placed in a 100 mL stainless steel ball mill (the total mass of the three powders was 5 g). 15 mL of n-heptane was added as a process control agent to prevent cold welding of the powders during the ball milling process. 50 g of stainless steel grinding balls with a diameter of 8 mm were added according to a mass ratio of 10:1. A planetary ball mill was used to mill the mixture at a speed of 350 rpm for 30 h under an argon atmosphere. The milling was performed in a forward and reverse alternating manner. The milling was stopped for 5 min after every 20 min of ball milling. Finally, the VTiFe solid solution (VTiFe) was obtained after drying at 80 °C for 10 h in a vacuum drying oven. 0.48 Ti 0.2 Fe 0.32 ).

[0065] (2) Preparation of MgH2-VTiFe composite material: 0.4g of the prepared V 0.48 Ti 0.2 Fe 0.32 The solid solution was used as a catalyst and mixed with 1.58g MgH2 powder under high purity argon atmosphere (where V 0.48 Ti0.2 Fe 0.32 The mass ratio of solid solution to MgH2 powder was 20:79), and MgH2-V was prepared by mechanical ball milling for 8 h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32 Mix the powder (wherein the ball-to-material ratio is 30:1, the ball mill speed is 400 rpm, the ball mill jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm).

[0066] (3) Preparation of magnesium-based hydrogen storage material: 0.02g CNTs powder and 1.98g MgH2-V prepared above were mixed. 0.48 Ti 0.2 Fe 0.32 The mixed powders (CNTs and MgH2-V 0.48 Ti 0.2 Fe 0.32 The mass ratio of the mixed powder is 1:99), and the magnesium-based hydrogen storage material (MgH2-20 wt.% VTiFe-1wt% CNTs mixed powder) based on the synergistic modification of VTiFe solid solution and CNTs is prepared by mechanical ball milling for 4 h under an argon atmosphere. The ball-to-material ratio during the ball milling process is 30:1, the ball milling speed is 400 rpm, the ball milling jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm.

[0067] Example 5

[0068] A magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification, the specific preparation method is as follows:

[0069] (1) Preparation of VTiFe solid solution: The VTiFe solid solution catalyst was prepared by wet ball milling. In a glove box filled with argon, 1.625 g of vanadium (V), 0.68 g of elemental titanium (Ti), and 2.695 g of elemental iron (Fe) powder were weighed and placed in a 100 mL stainless steel ball mill (the total mass of the three powders was 5 g). 15 mL of n-heptane was added as a process control agent to prevent cold welding of the powders during the ball milling process. 50 g of stainless steel grinding balls with a diameter of 8 mm were added according to a mass ratio of 10:1. A planetary ball mill was used to mill the mixture at a speed of 350 rpm for 30 h under an argon atmosphere. The milling was performed in a forward and reverse alternating manner. The milling was stopped for 5 min after every 20 min of ball milling. Finally, the VTiFe solid solution (VTiFe) was obtained after drying at 80 °C for 10 h in a vacuum drying oven. 0.48 Ti 0.2 Fe 0.32 ).

[0070] (2) Preparation of MgH2-VTiFe composite material: 0.04g of the prepared V 0.48 Ti 0.2 Fe 0.32 The solid solution was used as a catalyst and mixed with 1.86g MgH2 powder under high purity argon atmosphere (where V 0.48 Ti 0.2 Fe 0.32 The mass ratio of solid solution to MgH2 powder was 2:93), and MgH2-V was prepared by mechanical ball milling for 8 h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32 Mix the powder (wherein the ball-to-material ratio is 30:1, the ball mill speed is 400 rpm, the ball mill jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm).

[0071] (3) Preparation of magnesium-based hydrogen storage material: 0.1 g of CNTs powder was mixed with 1.9 g of the MgH2-V prepared above. 0.48 Ti 0.2 Fe 0.32 The mixed powders (CNTs and MgH2-V 0.48 Ti 0.2 Fe 0.32 The mass ratio of the mixed powder was 1:19), and the magnesium-based hydrogen storage material (MgH2-2wt.%VTiFe solid solution and CNTs synergistically modified) was prepared by mechanical ball milling for 4 h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32 -5wt.% CNTs mixed powder), wherein the ball-to-material ratio during ball milling is 30:1, the ball milling speed is 400 rpm, the ball milling jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm.

[0072] Example 6

[0073] A magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification, the specific preparation method is as follows:

[0074] (1) Preparation of VTiFe solid solution: The VTiFe solid solution catalyst was prepared by wet ball milling. In a glove box filled with argon, 1.625 g of vanadium (V), 0.68 g of elemental titanium (Ti), and 2.695 g of elemental iron (Fe) powder were weighed and placed in a 100 mL stainless steel ball mill (the total mass of the three powders was 5 g). 15 mL of n-heptane was added as a process control agent to prevent cold welding of the powders during the ball milling process. 50 g of stainless steel grinding balls with a diameter of 8 mm were added according to a mass ratio of 10:1. A planetary ball mill was used to mill the mixture at a speed of 350 rpm for 30 h under an argon atmosphere. The milling was performed in a forward and reverse alternating manner. The milling was stopped for 5 min after every 20 min of ball milling. Finally, the VTiFe solid solution (VTiFe) was obtained after drying at 80 °C for 10 h in a vacuum drying oven. 0.48 Ti 0.2 Fe 0.32 ).

[0075] (2) Preparation of MgH2-VTiFe composite material: 0.3g of the prepared V 0.48 Ti 0.2 Fe 0.32 The solid solution was used as a catalyst and mixed with 1.68g MgH2 powder under high purity argon atmosphere (where V 0.48 Ti 0.2 Fe 0.32 The mass ratio of solid solution to MgH2 powder was 5:28), and MgH2-V was prepared by mechanical ball milling for 8 h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32 Mix the powder (wherein the ball-to-material ratio is 30:1, the ball mill speed is 400 rpm, the ball mill jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm).

[0076] (3) Preparation of magnesium-based hydrogen storage material: 0.02g CNTs powder and 1.98g MgH2-V prepared above were mixed. 0.48 Ti 0.2 Fe 0.32 The mixed powders (CNTs and MgH2-V 0.48 Ti 0.2 Fe 0.32 The mass ratio of the mixed powder was 1:99), and the magnesium-based hydrogen storage material (MgH2-15wt.%VTiFe solid solution and CNTs synergistically modified) was prepared by mechanical ball milling for 4h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32-1wt.% CNTs mixed powder), wherein the ball-to-material ratio during ball milling is 30:1, the ball milling speed is 400 rpm, the ball milling jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm.

[0077] Example 7

[0078] A magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification, the specific preparation method is as follows:

[0079] (1) Preparation of VTiFe solid solution: The VTiFe solid solution catalyst was prepared by wet ball milling. In a glove box filled with argon, 1.625 g of vanadium (V), 0.68 g of elemental titanium (Ti), and 2.695 g of elemental iron (Fe) powder were weighed and placed in a 100 mL stainless steel ball mill (the total mass of the three powders was 5 g). 15 mL of n-heptane was added as a process control agent to prevent cold welding of the powders during the ball milling process. 50 g of stainless steel grinding balls with a diameter of 8 mm were added according to a mass ratio of 10:1. A planetary ball mill was used to mill the mixture at a speed of 350 rpm for 30 h under an argon atmosphere. The milling was performed in a forward and reverse alternating manner. The milling was stopped for 5 min after every 20 min of ball milling. Finally, the VTiFe solid solution (VTiFe) was obtained after drying at 80 °C for 10 h in a vacuum drying oven. 0.48 Ti 0.2 Fe 0.32 ).

[0080] (2) Preparation of MgH2-VTiFe composite material: 0.06g of the prepared V 0.48 Ti 0.2 Fe 0.32 The solid solution was used as a catalyst and mixed with 1.87 g MgH2 powder in a high-purity argon atmosphere (the mass ratio of VTiFe solid solution to MgH2 powder was 6:187), and MgH2-V was prepared by mechanical ball milling for 8 h in an argon atmosphere. 0.48 Ti 0.2 Fe 0.32 Mix the powder (wherein the ball-to-material ratio is 30:1, the ball mill speed is 400 rpm, the ball mill jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm).

[0081] (3) Preparation of magnesium-based hydrogen storage material: 0.07 g of CNTs powder was mixed with 1.93 g of the MgH2-V prepared above. 0.48 Ti 0.2 Fe 0.32 The mixed powders (CNTs and MgH2-V 0.48 Ti 0.2 Fe 0.32The mass ratio of the mixed powder was 7:193), and the magnesium-based hydrogen storage material (MgH2-3wt.%VTiFe solid solution and CNTs synergistically modified) was prepared by mechanical ball milling for 4h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32 -3.5wt.% CNTs mixed powder), wherein the ball-to-material ratio during ball milling is 30:1, the ball milling speed is 400rpm, the ball milling jar is a 100mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8mm and 6mm.

[0082] Example 8

[0083] A magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification, the specific preparation method is as follows:

[0084] (1) Preparation of VTiFe solid solution: The VTiFe solid solution catalyst was prepared by wet ball milling. In a glove box filled with argon, 1.625 g of vanadium (V), 0.68 g of elemental titanium (Ti), and 2.695 g of elemental iron (Fe) powder were weighed and placed in a 100 mL stainless steel ball mill (the total mass of the three powders was 5 g). 15 mL of n-heptane was added as a process control agent to prevent cold welding of the powders during the ball milling process. 50 g of stainless steel grinding balls with a diameter of 8 mm were added according to a mass ratio of 10:1. A planetary ball mill was used to mill the mixture at a speed of 350 rpm for 30 h under an argon atmosphere. The milling was performed in a forward and reverse alternating manner. The milling was stopped for 5 min after every 20 min of ball milling. Finally, the VTiFe solid solution (VTiFe) was obtained after drying at 80 °C for 10 h in a vacuum drying oven. 0.48 Ti 0.2 Fe 0.32 ).

[0085] (2) Preparation of MgH2-VTiFe composite material: 0.2g of the prepared V 0.48 Ti 0.2 Fe 0.32 The solid solution was used as a catalyst and mixed with 1.75g ​​MgH2 powder under high purity argon atmosphere (where V 0.48 Ti 0.2 Fe 0.32 The mass ratio of solid solution to MgH2 powder was 1:175), and MgH2-V was prepared by mechanical ball milling for 8 h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32 Mix the powder (wherein the ball-to-material ratio is 30:1, the ball mill speed is 400 rpm, the ball mill jar is a 100 mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8 mm and 6 mm).

[0086] (3) Preparation of magnesium-based hydrogen storage material: 0.05 g of CNTs powder was mixed with 1.95 g of the above-prepared MgH2-V 0.48 Ti 0.2 Fe 0.32 The mixed powders (CNTs and MgH2-V 0.48 Ti 0.2 Fe 0.32 The mass ratio of the mixed powder was 71:39), and the magnesium-based hydrogen storage material (MgH2-10wt.%VTiFe solid solution and CNTs synergistically modified) was prepared by mechanical ball milling for 4h under argon atmosphere. 0.48 Ti 0.2 Fe 0.32 -2.5wt.% CNTs mixed powder), wherein the ball-to-material ratio during ball milling is 30:1, the ball milling speed is 400rpm, the ball milling jar is a 100mL stainless steel jar, and the grinding balls are stainless steel grinding balls with diameters of 8mm and 6mm.

[0087] Performance tests (including initial hydrogen desorption temperature, hydrogen desorption over 5 minutes at 300°C, and hydrogen absorption over 10 minutes at 175°C) were conducted on the magnesium-based hydrogen storage materials prepared in Examples 1 and Examples 3-8 based on the synergistic modification of VTiFe solid solution and CNTs. The results are shown in Table 2. As can be seen from Table 2, the magnesium-based hydrogen storage materials formed by the synergistic modification of MgH2 powder by VTiFe solid solution and CNTs, when the VTiFe solid solution content is between 0.1 wt.% and 20 wt.% and the CNTs content is between 0.1 wt.% and 10 wt.%, can achieve excellent hydrogen storage performance.

[0088] Table 2 Hydrogen storage performance test of magnesium-based hydrogen storage materials prepared in Example 1 and Examples 3 to 8

[0089]

[0090]

[0091] Similarly, by changing the conditions in the preparation process of the above embodiment (such as: the range of the wet ball milling time in step (1) is 10 to 40 hours, the range of the ball milling speed is 300 rpm to 500 rpm, and the range of the ball-to-material ratio is 5:1 to 30:1, the range of the vacuum drying temperature in step (1) is 70°C to 100°C, and the range of the time is 2 to 10 hours, in step (2), the range of the ball-to-material ratio in the mechanical ball milling is 10:1 to 50:1, the range of the ball milling time is 5 to 10 hours, and the range of the ball milling speed is 350 rpm to 500 rpm, in step (3), the range of the ball-to-material ratio in the mechanical ball milling is 10:1 to 50:1, the range of the ball milling time is 2 to 5 hours, and the range of the ball milling speed is 350 rpm to 500 rpm), a magnesium-based hydrogen storage material based on the synergistic modification of VTiFe solid solution and CNTs can also be prepared, and its performance is similar to that of the products prepared in Examples 1 to 8, and both have good hydrogen storage performance.

[0092] In summary, the present invention discloses a magnesium-based hydrogen storage material based on the synergistic modification of VTiFe solid solution and CNTs. On the one hand, the VTiFe solid solution is used as a catalyst and has a single-phase face-centered cubic crystal structure. After composite ball milling with MgH2, it can be uniformly dispersed on the surface of the MgH2 matrix, and nano-α-Fe particles are precipitated in situ. The VTiFe catalysis provides a large number of active sites for hydrogen dissociation and diffusion, and effectively hinders the growth of grains during the cyclic hydrogen absorption and desorption process, thereby promoting the stable and efficient hydrogen storage dynamics of MgH2. On the other hand, CNTs are used as surface modification materials. During the ball milling process, they are broken into nano-films and adhere to the surface of MgH2 particles, effectively suppressing the agglomeration of particles during the cycle and greatly improving the cycle stability of MgH2. Therefore, MgH2 modified by VTiFe solid solution and CNTs has the following advantages: (1) stable hydrogen storage cycle kinetics, and the hydrogen storage capacity can still be maintained at more than 98.8% after 31 cycles of hydrogen absorption and desorption; (2) increased hydrogen release capacity and improved hydrogen release rate (at 300°C, the magnesium-based hydrogen storage material formed by VTiFe solid solution and CNTs modified MgH2 releases 5.8wt.% of hydrogen in just 5 minutes, while pure MgH2 can only release 3.4wt.% of hydrogen in 10 minutes at the same temperature, and the hydrogen release capacity has increased by 36%); (3) increased hydrogen absorption capacity (by adding 6wt.% VTiFe solid solution and 3wt.% CNTs, MgH2 can quickly absorb 5.6wt.% of hydrogen in 10 minutes at 175°C, while pure MgH2 can only absorb 1.6wt.% of hydrogen in 10 minutes at the same temperature. Even at 75°C, it can absorb 2.2wt.% of hydrogen in 30 minutes). The present invention also discloses a method for preparing a magnesium-based hydrogen storage material based on a VTiFe solid solution and synergistically modified with CNTs. The method involves first mixing elemental vanadium (V), elemental titanium (Ti), and elemental iron (Fe) and then wet-milling the VTiFe solid solution. The solution is then mixed with MgH2 powder and mechanically milled to produce a MgH2-VTiFe composite material. Finally, the material is further mixed with CNTs and mechanically milled. The method is simple and easy to operate, meeting the requirements for industrial application of magnesium-based hydrogen storage materials.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A magnesium-based hydrogen storage material based on VTiFe solid solution and CNTs synergistic modification, characterized in that: The magnesium-based hydrogen storage material includes VTiFe solid solution, CNTs and MgH2; The structural formula of the VTiFe solid solution is V x Ti y Fe z , where 0.1≤x≤0.5, 0.1≤y≤0.5, 0.1≤z≤0.5; The preparation method of the VTiFe solid solution comprises the following steps: mixing metal elements vanadium, titanium and iron with a purity of 99%, performing wet ball milling, and vacuum drying to obtain the VTiFe solid solution.

2. The magnesium-based hydrogen storage material according to claim 1, characterized in that In terms of mass percentage, the VTiFe solid solution in the magnesium-based hydrogen storage material is 0.1 wt.% to 20 wt.%, and the CNTs is 0.1 wt.% to 10 wt.%.

3. The magnesium-based hydrogen storage material according to claim 1, characterized in that In terms of mass percentage, the VTiFe solid solution in the magnesium-based hydrogen storage material is 2 wt.% to 15 wt.%, and the CNTs is 1 wt.% to 5 wt.%.

4. The magnesium-based hydrogen storage material according to claim 1, characterized in that In terms of mass percentage, the VTiFe solid solution in the magnesium-based hydrogen storage material is 3 wt.% to 10 wt.%, and the CNTs is 2.5 wt.% to 3.5 wt.%.

5. The method for preparing the magnesium-based hydrogen storage material according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: (1) Preparation of VTiFe solid solution: Mix vanadium, titanium and iron with a purity of 99%, perform wet ball milling, and vacuum dry to obtain VTiFe solid solution; (2) preparing a MgH2-VTiFe composite material: mixing the VTiFe solid solution and MgH2 powder, and performing mechanical ball milling to prepare a MgH2-VTiFe composite material; (3) Preparation of magnesium-based hydrogen storage material: The MgH2-VTiFe composite material and CNTs are mixed and mechanically ball milled to obtain a magnesium-based hydrogen storage material based on the synergistic modification of VTiFe solid solution and CNTs.

6. The preparation method according to claim 5, characterized in that In step (1), the milling jar and the milling balls used in the wet ball milling are made of stainless steel balls, argon is used as the ball milling atmosphere, and n-heptane or anhydrous ethanol is used as the ball milling process control agent.

7. The preparation method according to claim 5, characterized in that In step (1), the wet ball milling time is 10 to 40 hours, the ball milling speed is 300 rpm to 500 rpm, and the ball-to-material ratio is 5:1 to 30:1; In step (1), the vacuum drying is carried out in a vacuum drying oven at 70°C to 100°C for 2 to 10 hours.

8. The preparation method according to claim 5, characterized in that In step (2), the mechanical ball milling uses stainless steel balls, argon as the ball milling atmosphere, a ball-to-material ratio of 10:1 to 50:1, a ball milling time of 5 to 10 h, and a ball milling speed of 350 rpm to 500 rpm.

9. The preparation method according to claim 5, characterized in that In step (3), the mechanical ball milling uses stainless steel balls, argon as the ball milling atmosphere, a ball-to-material ratio of 10:1 to 50:1, a ball milling time of 2 to 5 h, and a ball milling speed of 350 rpm to 500 rpm.

10. Use of the magnesium-based hydrogen storage material according to any one of claims 1 to 4 in solid-state hydrogen storage.

Images