Hydrogen storage material additive, composite hydrogen storage material and preparation method of composite hydrogen storage material

Abstract

The invention discloses a hydrogen storage material additive, a composite hydrogen storage material and a preparation method thereof, relates to the technical field of hydrogen storage materials, and solves the problem of slow low-temperature hydrogen desorption kinetics of an existing hydrogen storage system. The additive is a CeO2 (at) TiO2 nanorod-shaped core-shell heterostructure of which the surface is loaded with Co metal, and the loading capacity of Co is 2wt.%. CeCl3. 7H2O and NaOH solution are used as raw materials for hydrothermal reaction, centrifugation, washing and drying to obtain CeO2 powder, the CeO2 powder is added into absolute ethyl alcohol, C16H36O4Ti and deionized water are added after stirring, centrifugation, washing and drying are performed after oil bath reaction to obtain a precursor, CeO2-TiO2 powder is obtained through calcination, CeO2-TiO2 powder is added into deionized water, Co (NO3) 2.3 H2O is added after stirring, stirring reaction, suction filtration and drying are performed, and then reducing gas calcination is performed to obtain the additive. The method can be used for a LiAlH4-AlH3 composite hydrogen storage system, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen storage materials, and particularly relates to a hydrogen storage material additive, a composite hydrogen storage material and a preparation method thereof. Background Art

[0002] As a clean and renewable energy source with high energy density, hydrogen energy is of great significance for building a clean, low-carbon, safe and efficient energy system. To achieve the widespread commercial application of hydrogen energy, it is necessary to overcome the barriers in the production, storage, transportation and application of hydrogen. Among them, the high-density and low-cost safe storage and transportation of hydrogen are the key links in the utilization of hydrogen energy.

[0003] The storage methods of hydrogen mainly include gaseous hydrogen storage, cryogenic liquid hydrogen storage, organic liquid hydrogen storage and solid-state hydrogen storage, each with its own advantages and disadvantages. Among them, light metal compound solid-state hydrogen storage materials have the characteristics of high volumetric hydrogen storage capacity and rapid dehydrogenation at relatively low pressures, and are a promising hydrogen storage method.

[0004] LiAlH4 has the characteristics of the highest theoretical hydrogen storage density (10.5 wt.%) and relatively low dehydrogenation temperature, but there are problems such as slow dehydrogenation kinetics, a long dehydrogenation temperature range, and lack of research on the catalyst mechanism, making it difficult to meet the requirements of practical applications. Forming a composite system of LiAlH4 and AlH3 to reduce the thermal stability of the hydride, the dehydrogenation kinetics of this composite hydrogen storage system has been greatly improved, but its dehydrogenation kinetics is relatively slow under low-temperature conditions, and further improvement of its low-temperature dehydrogenation kinetics is still needed.

[0005] In this regard, a Ni@CeO2 catalyst is disclosed in Chinese patent document CN117899884A, which can reduce the dehydrogenation starting temperature of LiAlH4 from 159.5 °C to 72.9 °C, and the hydrogen release amount within 2 h is increased to 4.34 wt.%. However, the above scheme has many limitations. On the one hand, Ni is prone to particle agglomeration during the dehydrogenation reaction, resulting in a reduction in active sites and a decrease in catalytic activity; on the other hand, due to the inherent defects of the CeO2 support such as low oxygen vacancy density, uneven distribution, poor electron conductivity and weak interfacial interaction, it is difficult to fully exert its catalytic activity when used as a catalyst support; and the CeO2 support is prone to sintering at high temperatures, further reducing the oxygen vacancy concentration and weakening the catalytic activity; the structural stability of the single CeO2 support is insufficient, and the nanorod morphology is prone to collapse during long-term use, further limiting the catalyst life.

[0006] Based on the above problems, there is an urgent need to develop a new catalyst system to break through the bottleneck of the existing technology. Summary of the Invention

[0007] To solve the problem of slow low-temperature hydrogen release kinetics in the existing composite hydrogen storage system LiAlH4 - AlH3, the present invention proposes a hydrogen storage material additive, a composite hydrogen storage material, and a preparation method thereof.

[0008] The technical solution of the present invention is as follows: A hydrogen storage material additive, wherein the hydrogen storage material additive is a CeO2@TiO2 nanorod-shaped core-shell heterostructure with Co metal loaded on the surface, and the loading amount of the Co metal is 2 wt.%.

[0009] The present invention also provides a preparation method of the above hydrogen storage material additive, including the following steps: S1. Using CeCl3·7H2O and NaOH solution as raw materials for hydrothermal reaction treatment. After the reaction ends, centrifuge, wash and dry the precipitate to obtain CeO2 powder. S2. Add the CeO2 powder into absolute ethanol, stir well, then add C 16 H 36 O4Ti and deionized water, and continuously stir and react in an oil bath. After the reaction ends, perform centrifugation, washing and drying treatments in sequence to obtain a CeO2@TiO2 core-shell nanoheterostructure precursor. S3. Calcinate the CeO2@TiO2 core-shell nanoheterostructure precursor in a muffle furnace to obtain CeO2@TiO2 powder. S4. Add the CeO2@TiO2 powder into deionized water, stir, then add Co(NO3)2·3H2O, stir for 4 h, and perform suction filtration and drying treatments after stirring ends to obtain a Co-CeO2@TiO2 precursor. S5. Calcinate the Co-CeO2@TiO2 precursor in a tubular furnace with a reducing gas to obtain the hydrogen storage material additive. Among them, in step S1, the dosage ratio of CeCl3·7H2O to the NaOH solution is 0.67 g:30 mL, and the concentration of the NaOH solution is 9 mol / L. In step S2, the dosage ratio of the CeO2 powder, C 16 H 36 O4Ti, absolute ethanol and deionized water is 0.003 mol:1 mL:100 mL:4 mL. In step S4, the mass ratio of CeO2@TiO2 to Co(NO3)2·3H2O is 98:9.9.

[0010] Preferably, in step S1, the hydrothermal reaction temperature is 160 °C and the time is 48 h.

[0011] Preferably, the temperature of the oil bath in step S2 is 70 °C, and the time for the stirring reaction is 24 h.

[0012] Preferably, the temperature for calcination in step S3 is 500 °C and the time is 4 h.

[0013] Preferably, the atmosphere for calcination in step S5 is Ar / H2, the temperature is 500 °C, and the time is 4 h.

[0014] The present invention also provides a composite hydrogen storage material, which is composed of LiAlH4 powder, AlH3 powder and the above-mentioned hydrogen storage material additive.

[0015] Preferably, the mass fractions of the LiAlH4 powder, AlH3 powder and the hydrogen storage material additive are 47.5 wt.%, 47.5 wt.% and 5 wt.%, respectively.

[0016] The present invention also provides a preparation method of the above-mentioned composite hydrogen storage material. The LiAlH4 powder, AlH3 powder and the hydrogen storage material additive are mixed evenly, and then ball milling treatment is carried out under a protective atmosphere to obtain the composite hydrogen storage material.

[0017] Preferably, the conditions for the ball milling treatment are as follows: Ball milling treatment is carried out using tungsten carbide beads; the ball-to-material ratio is 50:1, the rotation speed of the ball mill is 450 rpm, the single ball milling time is 10 min, with an interval of 5 min, and it is repeated 4 times.

[0018] Compared with the prior art, the present invention solves the problem of slow low-temperature hydrogen release kinetics existing in the existing composite hydrogen storage system LiAlH4 - AlH3 through the collaborative optimization of material design and defect engineering. The specific beneficial effects are as follows: The present invention first constructs CeO2@TiO2 core-shell nanorods, uses the TiO2 shell layer to protect the CeO2 core from high-temperature sintering, and at the same time, the interfacial electron coupling (such as d-band center shift, surface charge redistribution) significantly increases the oxygen vacancy concentration; further, calcination in a reducing atmosphere introduces transition metal Co and controllable oxygen vacancies O v , the d-orbital electron characteristics of Co (the d-band center is shifted upward by 0.3 eV compared to Ni), the strong electron interaction between Co and the core-shell interface optimizes the hydrogen adsorption / dissociation path, and the oxygen vacancy network accelerates the hydrogen diffusion kinetics. In addition, the heterostructure can effectively inhibit the agglomeration of Co particles and extend the catalyst life.

[0019] By adopting the LiAlH4-AlH3 composite hydrogen storage material, the present invention reduces the thermal stability of hydrogen release in the system; further, Co is loaded on the CeO2@TiO2 nanorod-shaped core-shell heterostructure to obtain an additive with low cost and high catalytic efficiency. When added to the LiAlH4-AlH3 composite system, it can achieve low-temperature and rapid hydrogen release performance, and a LiAlH4-AlH3-Co-CeO2@TiO2 hydrogen storage material with the best hydrogen release performance is obtained. This composite hydrogen storage material starts to release hydrogen at as low as 66.9 °C, and the hydrogen release capacity is 8.42 wt.% H2. And at a low temperature of 100 °C, 1.82 wt.% H2 can be released within 30 minutes, and the hydrogen release capacity is increased by nearly 13 times compared with the LAAH composite material.

[0020] Therefore, the Co-CeO2@TiO2 additive provided by the present invention for the LiAlH4-AlH3 composite hydrogen storage system has broad scientific value and application prospects. Brief Description of the Drawings

[0021] Figure 1 Transmission electron microscope image of Co-CeO2@TiO2 prepared in Example 1; Figure 2 XRD spectrum of Co-CeO2@TiO2 prepared in Example 1; Figure 3 X-ray photoelectron spectroscopy of Ce 3d, Ti 2p, and O 1s of Co-CeO2@TiO2 prepared in Example 1; Figure 4 Raman spectrum of Co-CeO2@TiO2 prepared in Example 1; Figure 5 N2 isothermal adsorption and desorption curve of Co-CeO2@TiO2 prepared in Example 1; Figure 6 Variable-temperature hydrogen release diagrams of LiAlH4-AlH3-Co-CeO2@TiO2 and LiAlH4-AlH3 prepared in Example 1; Figure 7 Isothermal hydrogen release diagrams of LiAlH4-AlH3-Co-CeO2@TiO2 and LiAlH4-AlH3 at 100 °C prepared in Example 1; Figure 8 Variable-temperature hydrogen release diagrams of LiAlH4-AlH3-Ni-CeO2@TiO2 and LiAlH4-AlH3 prepared in Comparative Example 1; Figure 9 Isothermal hydrogen release diagrams of LiAlH4-AlH3-Ni-CeO2@TiO2 and LiAlH4-AlH3 at 100 °C prepared in Comparative Example 1; Figure 10 Hydrogen desorption curves at variable temperatures of LiAlH4 - AlH3 - CeO2@TiO2 and LiAlH4 - AlH3 prepared in Comparative Example 2; Figure 11 Isothermal hydrogen desorption curves at 100 °C of LiAlH4 - AlH3 - CeO2@TiO2 and LiAlH4 - AlH3 prepared in Comparative Example 2; Figure 12 Hydrogen desorption curves at variable temperatures of LiAlH4 - AlH3 - Co - CeO2 and LiAlH4 - AlH3 prepared in Comparative Example 3; Figure 13 Isothermal hydrogen desorption curves at 100 °C of LiAlH4 - AlH3 - Co - CeO2 and LiAlH4 - AlH3 prepared in Comparative Example 3. Detailed implementation manners

[0022] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as a limitation of the present invention.

[0023] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.

[0024] Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0025] Secondly, the so - called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0026] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used, unless otherwise specified, are all conventional materials, reagents, methods, and instruments in the art, and those skilled in the art can obtain them through commercial channels.

[0027] Example 1. (1) Preparation of transition - metal - loaded core - shell heterostructure Co - CeO2@TiO2 powder: First, 0.67 g of CeCl3·7H2O was dissolved in 30 mL of a NaOH solution with a concentration of 9 mol / L. After vigorous stirring, it was transferred to an autoclave for a hydrothermal reaction at 160 °C for 48 h. Then, the solution after the hydrothermal reaction was centrifuged, washed, and dried (at 60 °C) to obtain CeO2 powder. Then, 0.003 mol of CeO2 powder was placed in 100 mL of absolute ethanol. After vigorous stirring, 1 mL of C 16 H 36 O4Ti, 4 mL of deionized water were added, and the reaction was carried out in an oil bath at 70 °C for 24 h. After centrifugation, washing, and drying, a CeO2@TiO2 precursor powder was obtained. The powder was calcined in a muffle furnace at 500 °C for 4 h to obtain a powder. 98 mg of the CeO2@TiO2 powder was dissolved in 60 mL of deionized water. After stirring, 9.9 mg of Co(NO3)2·6H2O was added. After stirring for 4 h, suction filtration, washing, and drying were carried out, and the sample was collected to obtain a Co-CeO2@TiO2 precursor powder. The powder was placed in a tubular furnace and calcined at 500 °C for 4 h in an Ar / H2 atmosphere to obtain Co-CeO2@TiO2 powder.

[0028] The obtained Co-CeO2@TiO2 powder was characterized by its microstructure and phase. The TEM image, XRD pattern, XPS spectrum, Raman spectrum, and BET curve are shown respectively as Figures 1 - 5 shown. As Figure 1 shown, TiO2 was loaded on the surface of CeO2 nanorods to form a core-shell nanoheterostructure, and Co metal was uniformly loaded on the CeO2@TiO2 nanorods, providing a morphological basis for the high-activity interface. According to Figure 2 shown, the XRD diffraction peaks of the synthesized Co-CeO2@TiO2 material were consistent with those of cubic fluorite-type CeO2 (JCPDS card 81-0792) and anatase-type TiO2 standard card (JCPDS card 71-1166). Due to the low content of Co and its high dispersion on the CeO2@TiO2 nanorods, no diffraction peaks related to Co species were observed in the XRD diffraction peaks. Figure 3 The XPS photoelectron spectrum of 3+ showed that Ce atoms in the Co-CeO2@TiO2 material consisted of Ce 4+ and Ce 4+ coexisting. The coexistence of multiple valence states was beneficial to electron transfer and accelerated the hydrogen evolution reaction. The Ti 2p mainly had two characteristic peaks. The characteristic peaks located at 458.79 eV and 464.45 eV corresponded to the 2p 1 / 2 and 2p 3 / 2 electron layers of Ti 4+exists in the form of. The O 1s has three peaks: defective oxygen at ~531 eV, lattice oxygen at ~529 eV, and adsorbed oxygen at ~533 eV. The existence of defective oxygen and Ce3+ proves that more oxygen vacancies are formed during the calcination process, confirming the high density of oxygen vacancies and the electron interaction at the Co-Ti-Ce interface, enhancing the catalytic activity. The Raman spectrum ( Figure 4 ) corresponds to the XRD spectrum and is mainly composed of the F -1 peak of CeO2 at ~459 cm 2g and the E -1 peak of TiO2 at ~144 cm g . The slight shift of the CeO2 peak position reflects the interfacial stress of the heterojunction, which promotes the stability of oxygen vacancies. The BET isothermal adsorption curve ( Figure 5 ) shows that the specific surface area of Co-CeO2@TiO2 is 17.79 m 2 g -1 .

[0029] (2) Preparation of LiAlH4-AlH3-Co-CeO2@TiO2 composite hydrogen storage material: Under an inert atmosphere, Co-CeO2@TiO2, LiAlH4 powder, and AlH3 powder were weighed according to mass fractions of 5 wt.%, 47.5 wt.%, and 47.5 wt.% respectively, placed in a ball milling jar. According to a ball-to-material ratio of 50:1, the corresponding mass of tungsten carbide beads was weighed, and ball milling was carried out at a rotation speed of 450 rpm. The total ball milling time was 40 min. To avoid the influence of the high temperature generated during ball milling on the sample performance, the ball mill stopped for 5 min every 10 min of milling. After ball milling, the sample was taken out in an inert atmosphere to obtain the LiAlH4-AlH3-Co-CeO2@TiO2 composite hydrogen storage material.

[0030] The variable temperature / constant temperature hydrogen release tests were carried out on the LiAlH4-AlH3-Co-CeO2@TiO2 obtained in (2) and the original sample LiAlH4-AlH3. The specific variable temperature hydrogen release curve is as shown in Figure 6 . It can be seen from the figure that the initial dehydrogenation temperature of LiAlH4-AlH3-Co-CeO2@TiO2 is reduced to 66.9 °C, which is about 13 °C lower than the initial hydrogen release temperature of LiAlH4-AlH3 (79.2 °C), and the hydrogen release capacity reaches 8.42 wt.% H2.

[0031] The isothermal hydrogen release diagrams of LiAlH4-AlH3-Co-CeO2@TiO2 and the original sample LiAlH4-AlH3 at 100 °C are as shown in Figure 7 . As shown by Figure 7It can be seen that the low-temperature kinetic performance of LiAlH4-AlH3-Co-CeO2@TiO2 is significantly improved compared with that of the original LiAlH4-AlH3, and it can release 1.82 wt.% within 30 min at 100 °C, which is significantly higher than the 0.142 wt.% of H2 released by LiAlH4-AlH3 under the same conditions.

[0032] Comparative Example 1. The difference between this comparative example and Example 1 is that Co(NO3)2·6H2O added in step (1) is replaced by Ni(NO3)2·6H2O. Specifically, the obtained transition metal-loaded core-shell heterostructure is Ni-CeO2@TiO2 powder, and the remaining process steps and parameter settings are the same as those in Example 1. The composite hydrogen storage material is prepared and named LiAlH4-AlH3-Ni-CeO2@TiO2.

[0033] The variable-temperature / constant-temperature hydrogen release tests are carried out on the obtained LiAlH4-AlH3-Ni-CeO2@TiO2 and LiAlH4-AlH3. Specifically, the variable-temperature hydrogen release curve is as Figure 8 shown. It can be seen from Figure 8 that the initial hydrogen release temperature of LiAlH4-AlH3-Ni-CeO2@TiO2 is 68.8 °C, and the capacity reaches 8.68 wt.%.

[0034] The 100 °C constant-temperature hydrogen release curves of LiAlH4-AlH3-Ni-CeO2@TiO2 and LiAlH4-AlH3 are as Figure 9 shown. It can be seen from Figure 9 that LiAlH4-AlH3-Ni-CeO2@TiO2 releases 1.21 wt.% of H2 within 30 min at 100 °C, and the hydrogen release kinetics is significantly improved compared with that of LiAlH4-AlH3. It is proved that the performance of the Co metal-loaded CeO2@TiO2 core-shell nanoheterostructure is better than that of the Ni metal. The main reason for this is the difference in the electronic structures of Co and Ni. The d-band center of Co is closer to the Fermi level, and the electron transfer ability is stronger, making it easier to form a strong coupling with oxygen vacancies; while the d orbit of Ni is deeper, and the electron interaction with oxygen vacancies is weaker, resulting in lower stability of oxygen vacancies.

[0035] Comparative Example 2. The difference between this comparative example and Example 1 is that Co(NO3)2·6H2O powder is not added in step (1). Specifically, the obtained core-shell heterostructure is CeO2@TiO2 powder, and the remaining process steps and parameter settings are the same as those in Example 1. The composite hydrogen storage material is prepared and named LiAlH4-AlH3-CeO2@TiO2.

[0036] Variable-temperature / constant-temperature hydrogen desorption tests were carried out on the obtained LiAlH4-AlH3-CeO2@TiO2 and LiAlH4-AlH3. The specific variable-temperature hydrogen desorption curve is as Figure 10 shown. It can be seen from Figure 10 that the initial dehydrogenation temperature of LiAlH4-AlH3-CeO2@TiO2 is 74.0 °C, and the hydrogen desorption capacity is 8.44 wt.% H2.

[0037] The 100 °C constant-temperature hydrogen desorption curves of LiAlH4-AlH3-CeO2@TiO2 and LiAlH4-AlH3 are as Figure 11 shown. It can be seen from Figure 11 that LiAlH4-AlH3-CeO2@TiO2 only releases 0.05 wt.% H2 at 100 °C for 30 min. By comparing with the data in Example 1, it can be proved that the CeO2@TiO2 core-shell heterostructure alone cannot improve the hydrogen desorption kinetic performance, while the loading of Co can produce a synergistic effect with the CeO2@TiO2 core-shell heterostructure. The strong electronic interaction between Co and the core-shell interface optimizes the hydrogen adsorption / dissociation path. In turn, the heterostructure can effectively inhibit the agglomeration of Co particles. The synergistic effect of the two significantly improves the low-temperature hydrogen desorption kinetic performance.

[0038] Comparative Example 3. The difference between this comparative example and Example 1 is that C 16 H 36 O4Ti liquid was not added in step (1), and the CeO2@TiO2 core-shell structure was not formed. Specifically, the obtained transition metal-loaded oxide additive is Co-CeO2 powder. The remaining process steps and parameter settings are the same as those in Example 1, and a composite hydrogen storage material was prepared and named LiAlH4-AlH3-Co-CeO2.

[0039] Variable-temperature / constant-temperature hydrogen desorption tests were carried out on the obtained LiAlH4-AlH3-Co-CeO2 and LiAlH4-AlH3. The specific variable-temperature hydrogen desorption curve is as Figure 12 shown. It can be seen from Figure 12 that the initial dehydrogenation temperature of LiAlH4-AlH3-Co-CeO2 is 73.6 °C, and the hydrogen desorption capacity is 7.98 wt.% H2.

[0040] The 100 °C constant-temperature hydrogen desorption curves of LiAlH4-AlH3-Co-CeO2 and LiAlH4-AlH3 are as Figure 13 shown. It can be seen from Figure 13 that LiAlH4-AlH3-Co-CeO2 only releases 0.796 wt.% H2 at 100 °C for 30 min.

[0041] By comparing with the data of Example 1, it can be proved that the core-shell structure CeO2@TiO2 of the present invention is significantly superior to the single CeO2 support, and the TiO2 shell inhibits the sintering of CeO2 and maintains the oxygen vacancy density. It is proved that the CeO2@TiO2 core-shell nanoheterostructure significantly improves the low-temperature hydrogen desorption kinetics performance.

[0042] In summary, LiAlH4-AlH3-Co-CeO2@TiO2 provided by the present invention solves the limitations of single components through the ternary synergy design of metal-support-defect. Experimental data show that the present invention has achieved significant performance improvement compared with Ni-based catalysts, Co supported on pure CeO2 supports, and the case without transition metals. The performance improvement is non-obvious, providing an innovative paradigm for the development of highly active hydrogen storage catalysts.

[0043] Obviously, the above embodiments are only examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A hydrogen storage material additive, characterized in that, The hydrogen storage material additive is a CeO2@TiO2 nanorod core-shell heterostructure with Co metal loaded on its surface, and the loading amount of the Co metal is 2 wt.%.

2. A preparation method of the hydrogen storage material additive as described in claim 1, characterized in that, It includes the following steps: S1. Using CeCl3·7H2O and NaOH solution as raw materials for hydrothermal reaction treatment. After the reaction ends, centrifuge, wash and dry the precipitate to obtain CeO2 powder; S2. Add the CeO2 powder into absolute ethanol, stir well, then add C 16 H 36 O4Ti and deionized water, continuously stir and react in an oil bath. After the reaction, perform centrifugation, washing, and drying treatments in sequence to obtain a CeO2@TiO2 core-shell nanoheterostructure precursor; S3. Calcinate the CeO2@TiO2 core-shell nanoheterostructure precursor in a muffle furnace to obtain CeO2@TiO2 powder; S4. Add the CeO2@TiO2 powder into deionized water, stir and then add Co(NO3)2·3H2O, stir for 4 h. After stirring ends, carry out suction filtration and drying treatment to obtain a Co-CeO2@TiO2 precursor; S5. Calcinate the Co-CeO2@TiO2 precursor in a tubular furnace with a reducing gas to obtain the hydrogen storage material additive; Among them, in step S1, the dosage ratio of CeCl3·7H2O and NaOH solution is 0.67 g: 30 mL, and the concentration of the NaOH solution is 9 mol / L; The dosages of the CeO2 powder, C 16 H 36 O4Ti, absolute ethanol and deionized water described in step S2 are in a ratio of 0.003 mol: 1 mL: 100 mL: 4 mL; In step S4, the mass ratio of CeO2@TiO2 to Co(NO3)2·3H2O is 98: 9.

9.

3. The preparation method of the hydrogen storage material additive according to claim 2, characterized in that, In step S1, the hydrothermal reaction temperature is 160 °C and the time is 48 h.

4. The preparation method of the hydrogen storage material additive according to claim 2, characterized in that, In step S2, the temperature of the oil bath is 70 °C and the stirring reaction time is 24 h.

5. The preparation method of the hydrogen storage material additive according to claim 2, characterized in that, In step S3, the calcination temperature is 500 °C and the time is 4 h.

6. The preparation method of the hydrogen storage material additive according to claim 2, characterized in that, In step S5, the calcination atmosphere is Ar / H2, the temperature is 500 °C, and the time is 4 h.

7. A composite hydrogen storage material, characterized in that, The composite hydrogen storage material is composed of LiAlH4 powder, AlH3 powder and the hydrogen storage material additive described in claim 1.

8. The composite hydrogen storage material according to claim 7, wherein, The mass fractions of the LiAlH4 powder, AlH3 powder and the hydrogen storage material additive are 47.5 wt.%, 47.5 wt.% and 5 wt.% respectively.

9. A method for preparing a composite hydrogen storage material as described in claim 7 or 8, characterized in that, Mix the LiAlH4 powder, AlH3 powder and the hydrogen storage material additive evenly, and then carry out ball milling treatment under a protective atmosphere to obtain the composite hydrogen storage material.

10. The preparation method of the composite hydrogen storage material according to claim 9, characterized in that, The conditions of the ball milling treatment are as follows: Use tungsten carbide beads for ball milling treatment; the ball-to-material ratio is 50:1, the rotation speed of the ball mill is 450 rpm, the single ball milling time is 10 min, with an interval of 5 min, and repeat 4 times.

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