Ti4O7-MgH2 composite hydrogen storage material and preparation method thereof

Abstract

The application belongs to the field of nanometer material preparation, and discloses a Ti4O7-MgH2 composite hydrogen storage material and a preparation method thereof, to solve the technical problems of slow hydrogen absorption kinetics, high initial hydrogen absorption and desorption temperature and difficult hydrogen absorption at low temperature of MgH2. In a hydrogen atmosphere, Ti4O7 with multivalent Ti and oxygen vacancies and MgH2 are ball milled to obtain Ti4O7-MgH2, i.e. the composite hydrogen storage material. The Ti4O7-MgH2 composite hydrogen storage material provided by the application has low initial hydrogen desorption temperature and excellent isothermal hydrogen absorption kinetics. The hydrogen absorption activation energy of the composite material is reduced to 33.92 KJ / mol; at 250 DEG C, the hydrogen absorption amount reaches saturation only in 2 min; and at 50 DEG C, the hydrogen absorption amount can reach 1.7 wt.% in 2 h. The composite material is prepared by a ball milling method, which is simple, low in energy consumption and has potential industrial production value.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nanomaterial preparation, and in particular to a composite hydrogen storage material. BACKGROUND

[0002] Hydrogen energy is a kind of energy with the characteristics of cleanliness, high efficiency, and renewability, and is known as the new energy of the 21st century and has attracted people's attention. However, the development and application of hydrogen energy involves four key areas of hydrogen production, storage, transportation and application. Hydrogen itself has the disadvantages of flammability and explosiveness, and has the problems of low volume energy density at normal temperature and pressure. Therefore, hydrogen storage technology has become a key problem restricting the large-scale application of hydrogen energy.

[0003] At present, the main hydrogen storage methods are high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage and solid-state hydrogen storage. Solid-state hydrogen storage is widely studied by researchers due to its high hydrogen storage density, high safety and excellent recyclability. At present, solid-state hydrogen storage is divided into metal hydride, coordination hydride, physical adsorption material and other hydrogen storage materials. Magnesium hydride is considered to be one of the most promising hydrogen storage materials due to its high hydrogen storage density, low cost, and abundant reserves. Its theoretical hydrogen storage capacity is as high as 7.6wt.%. However, the strong ionic bond of magnesium hydride leads to slow hydrogen absorption and desorption kinetics and high hydrogen absorption and desorption temperature, which limits the application of magnesium hydride. Therefore, researchers modify magnesium hydride by nanocrystallization, alloying, compounding and introducing catalysts. However, nanocrystallization, alloying and compounding of magnesium hydride have the problem of unstable hydrogen absorption and desorption cycle. Introducing a small amount of catalyst to modify the hydrogen storage performance of magnesium hydride is one of the most concerned hotspots of researchers and one of the simplest and most efficient methods to modify magnesium hydride. Catalysts can weaken the ionic bond energy between Mg-H, reduce the hydrogen desorption activation energy of magnesium hydride, and reduce the initial hydrogen desorption temperature of magnesium hydride. Catalysts can also promote the dissociation of hydrogen into hydrogen anions and provide channels for the nucleation of hydrogen anions and Mg. Therefore, introducing a catalyst is an effective method to improve the hydrogen storage performance of magnesium hydride. In the paper "Hydrogen sorption of magnesium hydride doped with nano-sized TiO2", rutile TiO2 is used to modify the hydrogen storage performance of magnesium hydride. The composite material is prepared by ball milling rutile TiO2 and magnesium hydride. The composite material needs 3 min to absorb hydrogen at 300℃, and the hydrogen absorption capacity is 4.40wt.%. Moreover, the composite material needs 10 min to absorb hydrogen at 250℃, and the hydrogen absorption capacity is only 3.54wt.%. Compared with the original magnesium hydride, the hydrogen storage performance of the composite material is improved. However, the composite material needs to be heated at high temperature to absorb hydrogen, and the hydrogen absorption capacity is low and the hydrogen absorption rate is slow, which seriously limits its commercial application and promotion. SUMMARY

[0004] In order to solve the technical problems of slow hydrogen absorption rate, high initial hydrogen absorption and desorption temperature and difficult hydrogen absorption at low temperature of magnesium hydride, the application provides a Ti4O7-MgH2 composite hydrogen storage material and a preparation method thereof.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the application is as follows:

[0006] A Ti4O7-MgH2 composite hydrogen storage material, wherein Ti4O7 is loaded on the surface of MgH2. 3+ The Ti in Ti4O7 has Ti 4+ , and oxygen vacancies. The 3d orbitals of Ti 3+ and Ti 4+ have empty orbitals. In the hydrogen desorption process of MgH2, the empty orbitals can accept the electrons of H - , and reduce H2. In the hydrogen absorption process of MgH2, the lone electron on the 3d orbital of Ti 3+ is returned to the sigma orbital of H2, and is dissociated into H - . Ov provides a channel for the migration of H - , and improves the kinetic performance of the hydrogen storage material.

[0007] The mass percentage of Ti4O7 in the composite hydrogen storage material is 1-10wt%. If the mass percentage of Ti4O7 is too high, the hydrogen storage content of the composite material will be affected, and too much catalyst will hinder the hydrogen absorption and desorption active sites of MgH2. Therefore, the content of Ti4O7 needs to be controlled within an appropriate range.

[0008] The hydrogen absorption activation energy of the Ti4O7-MgH2 composite hydrogen storage material is reduced to 33.92 KJ / mol.

[0009] The hydrogen absorption amount of the Ti4O7-MgH2 composite hydrogen storage material is 6.7wt.% at 250 DEG C for 30s, and the hydrogen absorption amount is saturated at 2min, and the maximum hydrogen absorption amount is 6.8wt.%.

[0010] The hydrogen absorption amount of the Ti4O7-MgH2 composite hydrogen storage material is 1.7wt.% at 50 DEG C for 2h.

[0011] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material is as follows: ball milling Ti4O7 and MgH2 in a hydrogen atmosphere, and the Ti4O7-MgH2 composite hydrogen storage material is obtained.

[0012] Further, the mass of Ti4O7 accounts for 1-10% of the total mass of Ti4O7 and MgH2.

[0013] Furthermore, in the aforementioned ball milling process, the ball-to-material ratio is 150-180:1, the milling speed is 300-700 rpm / min, and the milling time is 3-6 hours. A low ball-to-material ratio, low milling speed, and short milling time will result in uneven distribution of the composite material during milling; a high ball-to-material ratio, excessively high milling speed, and long milling time will cause more composite material to adhere to the metal balls, leading to greater losses. By controlling the ball-to-material ratio, milling speed, and milling time, the composite material can be evenly distributed while reducing energy consumption.

[0014] The beneficial effects of this invention are:

[0015] (1) This invention proposes a Ti4O7-MgH2 composite hydrogen storage material with a hydrogen absorption activation energy as low as 33.92 KJ / mol and a low hydrogen absorption temperature (i.e., it can absorb hydrogen even at 50℃). Ti4O7 is used as a catalyst, and the Ti in it possesses Ti... 3+ and Ti 4+ It also has oxygen vacancies. Ti 3+ and Ti 4+ The 3d orbitals of MgH2 contain empty orbitals. During hydrogen desorption, these empty orbitals can accept H+. - The electrons of MgH2 are reduced to H2; during the hydrogen absorption process, Ti 3+ The lone electron in the 3d orbital returns to the σ orbital of H2, dissociating into H2. - Ov is H - It provides a pathway for migration, thereby improving the kinetic performance of hydrogen storage materials.

[0016] (2) The Ti4O7-MgH2 composite hydrogen storage material proposed in this invention has a low initial hydrogen release temperature and excellent isothermal hydrogen absorption kinetics. Specifically, when the mass fraction of Ti4O7 in the composite material is 7 wt.%, the initial hydrogen release temperature is 241 °C. In addition, when the mass fraction of Ti4O7 is 7 wt.%, the composite material absorbs hydrogen at 250 °C, and the hydrogen absorption capacity can reach about 95% of the theoretical value (theoretical value is 7.068 wt.%) in only 30 seconds, and the maximum hydrogen absorption capacity can be reached in only 2 minutes; under the condition of 50 °C and 2 hours, the hydrogen absorption capacity can reach 1.7 wt.%, which has the advantage of low-temperature hydrogen absorption.

[0017] (3) The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of the present invention is simple and has low energy consumption. It only requires ball milling Ti4O7 and MgH2 in a hydrogen environment for 3-6 hours to obtain the material. Attached Figure Description

[0018] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only need to be some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0019] Figure 1 SEM of the composite hydrogen storage material prepared in Example 1 of the present application.

[0020] Figure 2 XRD of the composite hydrogen storage material prepared in Example 3 of the present application.

[0021] Figure 3 Temperature variation hydrogen release curve of the composite hydrogen storage material prepared in Examples 1-4 of the present application.

[0022] Figure 4 Temperature variation hydrogen release curve of the unmodified magnesium hydride in Comparative Example 1 of the present application.

[0023] Figure 5 Hydrogen absorption activation energy curve of the composite hydrogen storage material prepared in Example 3 of the present application; wherein (a) is hydrogen absorption JMAK equation; (b) is hydrogen absorption Arrhenius equation.

[0024] Figure 6 Isothermal hydrogen absorption curve of the composite hydrogen storage material prepared in Example 3 of the present application at different temperatures; wherein (a) is the isothermal hydrogen absorption curve of 0-120 min; (b) is an enlarged view of the isothermal hydrogen absorption curve of 0-20 min in (a).

[0025] Figure 7 Isothermal hydrogen absorption curve of the unmodified magnesium hydride in Comparative Example 1 of the present application at 250℃. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described clearly and completely in combination with the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present application.

[0027] Example 1

[0028] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material in the present embodiment is as follows:

[0029] 0.03g of Ti4O7 and 0.97g of commercial magnesium hydride were placed in a ball mill tank in an argon environment glove box, 5MPa hydrogen was filled in the ball mill tank, and ball milling was carried out under the hydrogen atmosphere, the ball-to-material ratio was 160:1, the rotation speed was 400r / min, and the ball milling time was 4h, to obtain Ti4O7-3wt.%-MgH2, i.e. the composite hydrogen storage material. Figure 1 The SEM of the composite hydrogen storage material prepared in Example 1 was shown in the figure, and it could be seen that Ti4O7 was attached to the surface of MgH2, and Ti4O7 provided a large number of active sites for hydrogen absorption and release of MgH2.

[0030] Example 2

[0031] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of the present embodiment was as follows:

[0032] 0.05g of Ti4O7 and 0.95g of commercial magnesium hydride were placed in a ball mill tank in an argon environment glove box, 5MPa hydrogen was filled in the ball mill tank, and ball milling was carried out under the hydrogen atmosphere, the ball-to-material ratio was 160:1, the rotation speed was 400r / min, and the ball milling time was 4h, to obtain Ti4O7-5wt.%-MgH2, i.e. the composite hydrogen storage material.

[0033] Example 3

[0034] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of the present embodiment was as follows:

[0035] 0.07g of Ti4O7 and 0.93g of commercial magnesium hydride were placed in a ball mill tank in an argon environment glove box, 5MPa hydrogen was filled in the ball mill tank, and ball milling was carried out under the hydrogen atmosphere, the ball-to-material ratio was 160:1, the rotation speed was 400r / min, and the ball milling time was 4h, to obtain Ti4O7-7wt.%-MgH2, i.e. the composite hydrogen storage material.

[0036] Figure 2 The XRD of the composite hydrogen storage material prepared in the present embodiment was shown in the XRD spectrum, and it could be observed that the sample after ball milling only had MgH2 and Ti4O7, which proved that the sample was not contaminated and oxidized during the ball milling process.

[0037] Example 4

[0038] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of the present embodiment was as follows:

[0039] 0.1 g of Ti4O7 and 0.9 g of commercial magnesium hydride were placed in a ball mill tank in an argon environment glove box, 5 MPa hydrogen was filled in the ball mill tank, and ball milling was carried out under a hydrogen atmosphere, the ball-to-material ratio was 160:1, the rotation speed was 400 r / min, and the ball milling time was 4 h, to obtain Ti4O7-10 wt.%-MgH2, i.e., a composite hydrogen storage material.

[0040] Example 5

[0041] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material in this example was as follows:

[0042] 0.01 g of Ti4O7 and 0.99 g of commercial magnesium hydride were placed in a ball mill tank in an argon environment glove box, 5 MPa hydrogen was filled in the ball mill tank, and ball milling was carried out under a hydrogen atmosphere, the ball-to-material ratio was 160:1, the rotation speed was 400 r / min, and the ball milling time was 4 h, to obtain Ti4O7-1 wt.%-MgH2, i.e., a composite hydrogen storage material.

[0043] Example 6

[0044] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material in this example was as follows:

[0045] 0.07 g of Ti4O7 and 0.93 g of commercial magnesium hydride were placed in a ball mill tank in an argon environment glove box, 0.5 MPa hydrogen was filled in the ball mill tank, and ball milling was carried out under a hydrogen atmosphere, the ball-to-material ratio was 150:1, the rotation speed was 380 r / min, and the ball milling time was 4 h, to obtain Ti4O7-7 wt.%-MgH2, i.e., a composite hydrogen storage material.

[0046] Example 7

[0047] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material in this example was as follows:

[0048] 0.07 g of Ti4O7 and 0.93 g of commercial magnesium hydride were placed in a ball mill tank in an argon environment glove box, 0.5 MPa hydrogen was filled in the ball mill tank, and ball milling was carried out under a hydrogen atmosphere, the ball-to-material ratio was 155:1, the rotation speed was 350 r / min, and the ball milling time was 4 h, to obtain Ti4O7-7 wt.%-MgH2, i.e., a composite hydrogen storage material.

[0049] Example 8

[0050] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material in this example was as follows:

[0051] 0.07 g of Ti4O7 and 0.93 g of commercial magnesium hydride were placed in a ball mill tank in an argon environment glove box, the ball mill tank was filled with 0.5 MPa hydrogen, and ball milling was carried out under a hydrogen atmosphere, the ball-to-material ratio was 165:1, the rotation speed was 450 r / min, and the ball milling time was 5 h, to obtain Ti4O7-7wt.%-MgH2, i.e. a composite hydrogen storage material.

[0052] Example 9

[0053] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of the present example is as follows:

[0054] 0.07 g of Ti4O7 and 0.93 g of commercial magnesium hydride were placed in a ball mill tank in an argon environment glove box, the ball mill tank was filled with 0.5 MPa hydrogen, and ball milling was carried out under a hydrogen atmosphere, the ball-to-material ratio was 150:1, the rotation speed was 700 r / min, and the ball milling time was 3 h, to obtain Ti4O7-7wt.%-MgH2, i.e. a composite hydrogen storage material.

[0055] Example 10

[0056] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of the present example is as follows:

[0057] 0.07 g of Ti4O7 and 0.93 g of commercial magnesium hydride were placed in a ball mill tank in an argon environment glove box, the ball mill tank was filled with 0.5 MPa hydrogen, and ball milling was carried out under a hydrogen atmosphere, the ball-to-material ratio was 180:1, the rotation speed was 300 r / min, and the ball milling time was 6 h, to obtain Ti4O7-7wt.%-MgH2, i.e. a composite hydrogen storage material.

[0058] Comparative Example 1

[0059] 1.00 g of commercial magnesium hydride was placed in a ball mill tank in an argon environment glove box, the ball mill tank was filled with 0.5 MPa hydrogen, and ball milling was carried out under a hydrogen atmosphere, the ball-to-material ratio was 160:1, the rotation speed was 400 r / min, and the ball milling time was 4 h, to obtain unmodified magnesium hydride.

[0060] Implementation Effect Example

[0061] (1) Variable-temperature hydrogen release performance test

[0062] The sample was placed in a reactor in the glove box, then the reactor valve was closed, the reactor was taken out of the glove box and placed in a heating device, and the reactor was connected to the test device and vacuumized by the test hydrogen release device, the heating device was heated from room temperature to 500℃ at a rate of 5℃ / min, and the test device started to record the sample hydrogen release data when the heating device started to heat, until the heating ended. Figure 3As shown in the figure, the initial hydrogen release temperature of the composite material is 241°C when the mass fraction of Ti4O7 is 7wt.%, which is relatively low compared to 281°C when the mass fraction of Ti4O7 is 5wt.% and 291°C when the mass fraction of Ti4O7 is 3wt.%; when the mass fraction of Ti4O7 is 10wt.%, the initial hydrogen release temperature of the composite material is 274°C, and when the catalyst content is too high, it hinders the active sites of MgH2 for releasing hydrogen, making the diffusion of H2 slow. Under certain conditions, when the mass fraction of Ti4O7 is high, it can better catalyze magnesium hydride. Figure 4 The temperature change hydrogen release curve of the modified magnesium hydride prepared for Comparative Example 1 is shown in the figure, and it can be seen from the figure that the initial hydrogen release temperature of the unmodified magnesium hydride is 315°C. The initial hydrogen release temperature of different Ti4O7 contents and the initial hydrogen release temperature of Ti4O7-7wt.%-MgH2 at different rotation speeds and different ball-to-material ratios are shown in Tables 1 and 2, respectively, as follows.

[0063] Table 1 is a statistical table of the initial hydrogen release temperature of different Ti4O7 contents

[0064] Ti4O7 / g MgH2 / g Rotation speed (r / min) Ball to material ratio Initial hydrogen release temperature (°C) Example 1 0.03 0.97 400 160:1 291 Example 2 0.05 0.95 400 160:1 281 Example 3 0.07 0.93 400 160:1 241 Example 4 0.1 0.90 400 160:1 274 Example 5 0.01 0.99 400 160:1 310 Comparative Example 1 0 1 400 160:1 315

[0065] Table 2 is a statistical table of the initial hydrogen release temperature of Ti4O7-7wt.%-MgH2 at different rotation speeds and different ball-to-material ratios

[0066] Ti4O7 / g MgH2 / g Rotation speed (r / min) Ball to material ratio Initial hydrogen release temperature (°C) Example 3 0.07 0.93 400 160:1 241 Example 6 0.07 0.93 380 150:1 245 Example 7 0.07 0.93 350 155:1 248 Example 8 0.07 0.93 450 165:1 242 Example 9 0.07 0.93 700 150:1 244 Example 10 0.07 0.93 300 180:1 255

[0067] As can be seen from Tables 1 and 2, when the content of Ti4O7 is too low, the initial hydrogen release temperature of the composite material is high, because less catalyst cannot provide sufficient active sites for MgH2 to react; when the content of Ti4O7 is too high, the initial hydrogen release temperature of the composite material will be high, because more catalyst hinders the active sites of MgH2 for reaction, and the final result proves that when the mass fraction is 7wt.%, the initial hydrogen release temperature is the lowest, and the initial hydrogen release temperature is 241°C. Within a certain range, the change of rotation speed and ball-to-material ratio has little effect on the initial hydrogen release temperature of the composite material. When the rotation speed is 400r / min and the ball-to-material ratio is 160:1, the initial hydrogen release temperature of the composite material is the lowest, and the initial hydrogen release temperature is 241°C.

[0068] (2) Activation energy test

[0069] The MgH2-7wt.%-Ti4O7 composite material is tested for isothermal hydrogen absorption at three constant temperatures of 100℃, 150℃ and 200℃, and equation (1) is used to fit the isothermal hydrogen absorption data of the MgH2-7wt.%-Ti4O7 composite material, wherein α represents the reaction progress, t represents the reaction time, n represents the Avrami index, and k represents the reaction rate constant; equation (2) is used to fit the activation energy, R represents the gas constant, T represents the reaction temperature, and K0 represents the Arrhenius constant.

[0070] Ln[-Ln(1-α)]=n Ln t+n Ln k (1)

[0071] Ea=-R T Ln(k / k0) (2)

[0072] It can be seen from Figure 5 that the hydrogen absorption activation energy is 33.92±5.70kJ / mol.

[0073] (3) Constant temperature hydrogen absorption performance test

[0074] During the isothermal hydrogen absorption test, the sample is placed in the reactor in an argon environment glove box, the reactor is vacuumed, then the valve is closed, the hydrogen pressure of the hydrogen cylinder is set to a constant pressure of 50bar, the reactor is heated to a preset temperature, when the temperature is constant at the preset temperature, the reactor valve is opened, and the isothermal hydrogen absorption data is tested after the reactor valve is opened. Figure 6 The isothermal hydrogen absorption curve of the composite hydrogen storage material prepared in Example 3 at different temperatures is shown in the figure, and it can be seen from the figure that at 250℃, the hydrogen absorption amount can reach 95% of the theoretical value (hydrogen absorption amount is 6.7wt.%) only in 30s, the hydrogen absorption amount is 6.8wt.% in 2min, reaching 96% of the theoretical value, and reaching the maximum hydrogen absorption amount; the hydrogen absorption amount is 6.55wt.% in 15min at 200℃, reaching 93% of the theoretical value; the hydrogen absorption amount is 6.36wt.% in 25min at 150℃, reaching 90% of the theoretical value; the final hydrogen absorption amount is 5.2wt.% at 100℃, reaching 71.62% of the theoretical value. In addition, the hydrogen absorption amount is 1.7wt.% at 50℃, and the hydrogen absorption time is 2h, reaching 24.05% of the theoretical value, and the composite material has the advantage of low-temperature hydrogen absorption.

[0075] Figure 7The isothermal hydrogen absorption curve of the unmodified magnesium hydride in the present application comparative example 1 at 250℃ is shown in the figure, it can be seen from the figure that the unmodified magnesium hydride needs about 25 min to reach the stable state of hydrogen absorption at 250℃, compared with the MgH2-7wt.%Ti4O7 composite material, the time required to reach the stable state of hydrogen absorption is longer. It can be seen that the addition of the catalyst can accelerate the hydrogen absorption rate, shorten the equipment holding time and reduce the energy consumption.

[0076] In the present application, Ti4O7 is loaded on the surface of MgH2, which weakens the Mg-H ionic bond energy, reduces the initial dehydrogenation temperature, provides a large number of active sites for Mg hydrogen absorption, reduces the hydrogen absorption activation energy, and accelerates the hydrogen absorption rate at high temperature.

[0077] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A Ti4O7-MgH2 composite hydrogen storage material, characterized in that, The Ti4O7-MgH2 composite hydrogen storage material is Ti4O7 loaded on the surface of MgH2, wherein the mass percentage of Ti4O7 is 1-10 wt%. 2.The Ti 4O 7-MgH 2 composite hydrogen storage material of claim 1, wherein, The Ti4O7 has oxygen vacancies, and the valence of Ti is +3 and +4. 3.The Ti 4O 7-MgH 2 composite hydrogen storage material of claim 1, wherein, The hydrogen absorption activation energy of the Ti4O7 / MgH2 composite hydrogen storage material is reduced to 33.92 KJ / mol. 4.The Ti 4O 7-MgH 2 composite hydrogen storage material of claim 1, wherein, The hydrogen absorption amount of the Ti4O7 / MgH2 composite hydrogen storage material is 6.7 wt.% at 250℃ for 30s, and the hydrogen absorption amount reaches saturation at 2 min, and the maximum hydrogen absorption amount is 6.8 wt.%. 5.The Ti 4O 7-MgH 2 composite hydrogen storage material of claim 1, wherein, The hydrogen absorption amount of the Ti4O7 / MgH2 composite hydrogen storage material can reach 1.7 wt.% at 50℃ for 2 h.

6. The method for preparing the Ti4O7-MgH2 composite hydrogen storage material of claim 1, characterized in that, The steps are as follows: ball milling Ti4O7 and MgH2 in a hydrogen atmosphere, and the Ti4O7 / MgH2 composite hydrogen storage material is obtained.

7. The method of claim 6, wherein the Ti4O7-MgH2 composite hydrogen storage material is prepared by the steps of: (a) mixing Ti4O7 and MgH2 powders; (b) heating the mixture to a temperature of 300-400°C; and (c) cooling the mixture to room temperature. The mass of the Ti4O7 accounts for 1-10% of the total mass of Ti4O7 and MgH2.

8. The preparation method of the Ti4O7-MgH2 composite hydrogen storage material according to claim 7, characterized in that, The ball-to-material ratio in the ball milling process is 150-180:

1.

9. The method of claim 8, wherein the Ti4O7-MgH2 composite hydrogen storage material is prepared by a process comprising: a) mixing Ti4O7 and MgH2 powders; b) heating the mixture to a temperature of 300-400°C; and c) cooling the mixture to room temperature. The rotation speed of the ball milling is 300-700 rpm / min.

10. The preparation method of the Ti4O7-MgH2 composite hydrogen storage material according to claim 9, characterized in that, The ball milling time is 3-6 h.

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