Rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material and method for preparing the same

Abstract

The application discloses a rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material and a preparation method thereof. The rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material comprises a rare earth nitride and an aminomagnesium-lithium hydride composite system. The preparation method comprises the following steps: mixing aminomagnesium with lithium hydride, adding the rare earth nitride in the mixing process, transferring the mixed mixture into a ball mill tank, and ball milling under inert gas protection to obtain the rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material. The raw material synthesis process is simple and controllable, and the cost is low. The hydrogen storage performance of the aminomagnesium-lithium hydride composite hydrogen storage material can be obviously improved by adding a small amount of the rare earth nitride. Moreover, the rare earth nitride can be purchased through a commercial channel, and the adding mode can be directly mixed with the raw material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid-state hydrogen storage, and particularly relates to a rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material and a preparation method thereof, and application of the rare earth nitride in improving hydrogen storage performance of the aminomagnesium-lithium hydride composite system. BACKGROUND

[0002] New energy vehicle industry is one of the strategic emerging industries. In order to meet the growing demand, researchers are committed to developing more efficient, safe and sustainable on-board hydrogen storage materials. Among them, metal nitrogen hydride hydrogen storage materials have attracted widespread attention and research, especially the lithium magnesium nitrogen hydride (Li-Mg-N-H) system. This system has high hydrogen storage capacity and fast hydrogen charging and discharging rate, showing great potential. However, its hydrogen absorption and desorption performance and cycle stability have not fully met the standards of practical application.

[0003] By mixing aminomagnesium and lithium hydride at a certain molar ratio, for example, according to the molar ratio of 1:2, an aminomagnesium-lithium hydride composite system can be formed. The sample is prepared and the hydrogen absorption and desorption reaction is as follows:

[0004]

[0005] Under this component, the composite system can hold 5.6wt% of the mass hydrogen storage density. The composite system of this component is heated to about 130℃ to start releasing hydrogen, and has fast reversible hydrogen absorption and desorption performance at 200℃, but the kinetic performance is poor and the hydrogen absorption and desorption rate is slow.

[0006] In order to overcome the limitations of Li-Mg-N-H in hydrogen storage, researchers are using various methods for optimization. Among them, including component regulation, nanocrystallization and adding catalysts. Through component regulation, the chemical composition of Li-Mg-N-H can be changed, thereby improving the hydrogen absorption and desorption performance and cycle stability. The nanocrystallization method controls the particle size of the Li-Mg-N-H hydrogen storage system to be in the nanometer scale, thereby increasing the specific surface area and reaction activity, and improving the hydrogen storage performance. Adding catalysts is considered to be the most effective way to improve the hydrogen storage performance of Li-Mg-N-H, because the catalysts can provide adsorption active sites, promote the adsorption and dissociation of hydrogen molecules, and thereby significantly improve the hydrogen storage performance of the Li-Mg-N-H system.

[0007] The patent specification with publication number CN101623627A discloses a catalyst (Ti-Cr-V)-Mn-R alloy for improving the hydrogen release kinetics of Li-Mg-N-H system hydrogen storage material, wherein R is Ce or Ce-rich mixed rare earth, and the composition and content of the alloy are as follows: titanium element 20-30wt%, vanadium element 30-45wt%, chromium element 25-35wt%, manganese element 5-15wt%, and R 1-5wt%. The (Ti-Cr-V)-Mn-R alloy can be compounded with Li-Mg-N-H system material by ball milling, and the compounding ratio of the (Ti-Cr-V)-Mn-R alloy to the Li-Mg-N-H system material is 1-15mol%. The specific ball milling process parameters are as follows: ball-to-material weight ratio 5-15:1, ball milling time 5-30 hours, and the tank is filled with 0.5-3MPa protective atmosphere. The catalyst described in the patent technology can make the Li-Mg-N-H composite hydrogen storage material increase by more than 1 times in 1 hour of hydrogen release at 200℃.

[0008] The patent specification with publication number CN112265958A discloses a composite hydrogen storage material and a preparation method thereof. The composite hydrogen storage material comprises aminomagnesium, lithium hydride, and alkali metal silicon hydride, wherein the molar ratio of aminomagnesium to lithium hydride is 1:2, and the addition amount of alkali metal silicon hydride is 1-15mol%. The preparation method of the composite hydrogen storage material is as follows: weighing aminomagnesium, lithium hydride, and alkali metal silicon hydride, mixing them, and placing them in a ball milling tank, vacuumizing the ball milling tank, filling it with hydrogen pressure, and then placing the ball milling tank in a ball mill for ball milling.

[0009] The patent specification with publication number CN101733155A discloses a MCoH x (M=Ti or Zr, 1≤x≤3) catalyst and a preparation method thereof, and the MCoH x catalyst / Li-Mg-B-N-H reversible hydrogen storage material and a preparation method thereof. The MCoH x The catalyst is obtained by induction melting, hydrogenation, and dehydrogenation cycles. The MCoH x The catalyst is hydrogenated with Mg powder in a high-pressure hydrogen atmosphere by ball milling to obtain catalytic MgH2 powder, and then the catalytic MgH2 powder is mixed with LiNH2 and LiBH4 in a molar ratio of (1.0-1.1):2:(0.1-0.3) and subjected to ball milling and compounding treatment in an argon or nitrogen atmosphere to prepare a Li-Mg-B-N-H catalytic reversible hydrogen storage material, achieving a reversible hydrogen release of more than 4.6wt% at 150℃ and 0.1MPa. SUMMARY

[0010] The application provides a rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material, which has simple and controllable raw material synthesis process and low cost.

[0011] A rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material, comprising a rare earth nitride and an aminomagnesium-lithium hydride composite system.

[0012] The rare earth nitride in the rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material can be at least one of SmN (samarium nitride), CeN (cerium nitride), NdN (neodymium nitride), PrN (praseodymium nitride) and LaN (lanthanum nitride).

[0013] In an embodiment, the rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material, with the total mass of the aminomagnesium-lithium hydride composite system and the rare earth nitride being 100%, the mass ratio of the rare earth nitride can be no more than 10%.

[0014] Through a large number of experiments, the inventors unexpectedly found that in the rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material, the addition of 5wt% (with the total mass of the aminomagnesium-lithium hydride composite system and the rare earth nitride being 100%) of cerium nitride can obtain the aminomagnesium-lithium hydride composite hydrogen storage material with the best hydrogen absorption and release performance, and the cerium nitride can effectively improve the hydrogen storage performance of the aminomagnesium-lithium hydride composite hydrogen storage material.

[0015] In an embodiment, the rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material, the molar ratio of aminomagnesium and lithium hydride in the aminomagnesium-lithium hydride composite system can be 1:2.

[0016] The application also provides a preparation method of the rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material, in which aminomagnesium and lithium hydride are mixed, a rare earth nitride is added during the mixing process, and the mixed material after mixing is transferred to a ball mill tank for ball milling under the protection of inert gas to obtain the rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material.

[0017] In an embodiment, the preparation method of the rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material, the parameters of the ball milling are as follows: the ball-to-material ratio is 110-130:1, stainless steel balls with two diameters of 6mm and 10mm are used, the ball milling speed is 400-600rpm, the ball milling time is 24-48h, and the intermittent ball milling process is used.

[0018] In an embodiment, the inert gas can be a noble gas, such as argon.

[0019] As a general inventive concept, the present application also provides a use of a rare earth nitride in improving the hydrogen storage performance of an aminomagnesium-lithium hydride composite system.

[0020] In the use, the rare earth nitride can be at least one of SmN, CeN, NdN, PrN, and LaN.

[0021] In the use, the mass fraction of the rare earth nitride in the total mass of the aminomagnesium-lithium hydride composite system and the rare earth nitride can be no more than 10%.

[0022] Through a large number of experiments, the inventors unexpectedly found that, in the use, when the rare earth nitride is selected to be cerium nitride and the addition amount is 5wt% (based on the total mass of the aminomagnesium-lithium hydride composite system and the rare earth nitride being 100%), the obtained aminomagnesium-lithium hydride composite hydrogen storage material has the best hydrogen absorption and desorption performance, and the cerium nitride effectively improves the hydrogen storage performance of the aminomagnesium-lithium hydride composite hydrogen storage material.

[0023] In the use, the molar ratio of aminomagnesium to lithium hydride in the aminomagnesium-lithium hydride composite system can be 1:2.

[0024] The aminomagnesium involved in the technical solution of the present application can be obtained by ammonia pressure ball milling-ammonia pressure holding, and specifically, can be prepared by the following steps:

[0025] Step (1), the magnesium powder is loaded into a ball mill tank with a high-pressure gas valve, and high-energy ball milling is performed in an ammonia atmosphere of 6-8 bar to obtain a gray-black powder;

[0026] Step (2), the gray-black powder obtained in step (1) is transferred into a reaction container with a high-pressure gas valve, and holding is performed at 280-320℃ in an ammonia atmosphere of 6-8 bar. During the holding process, the ammonia pressure will decrease. In order to maintain the ammonia absorption effect, ammonia is supplemented in time. When the ammonia pressure no longer changes, the obtained white powder is the aminomagnesium powder.

[0027] In an embodiment, in step (1), the ball-to-material ratio of the high-energy ball milling can be 110-130:1.

[0028] In an embodiment, in step (1), two diameters of stainless steel milling balls, 6mm and 10mm, can be used.

[0029] In an embodiment, in step (1), the rotation speed of the high-energy ball milling can be 400-600rpm.

[0030] In one embodiment, in step (1), the high-energy ball milling time can be 8-12 h.

[0031] The aminomagnesium-lithium hydride composite hydrogen storage material is directly prepared by the above method, thereby ensuring the phase purity of the raw material of the aminomagnesium-lithium hydride composite hydrogen storage material.

[0032] The conventional Li-Mg-N-H composite hydrogen storage system is obtained by mixing lithium amide and magnesium hydride and then releasing and absorbing hydrogen once to obtain aminomagnesium-lithium hydride, but the aminomagnesium-lithium hydride hydrogen storage system obtained by the method has the defects of incomplete conversion, complex phase and poor hydrogen release and absorption kinetics. The aminomagnesium-lithium hydride composite hydrogen storage system is directly prepared by the aminomagnesium prepared by the method, which ensures the phase purity and makes the aminomagnesium itself have higher hydrogen storage performance than the conventional Li-Mg-N-H.

[0033] The rare earth nitrides involved in the technical scheme of the application can be obtained by commercial channels or according to the prior art.

[0034] Compared with the prior art, the application has the beneficial effects of:

[0035] The application provides a rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material and a preparation method thereof, the raw material synthesis process is simple and controllable, and the cost is low. The hydrogen storage performance of the aminomagnesium-lithium hydride composite hydrogen storage material can be significantly improved by adding a small amount of rare earth nitride, and the rare earth nitride can be purchased through commercial channels and added directly with the raw material.

[0036] The rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material has the characteristics of low initial hydrogen absorption and release temperature, high hydrogen release amount and high hydrogen absorption and release rate.

[0037] The application first finds that the rare earth nitride added into the aminomagnesium-lithium hydride composite system can act as a catalyst, reduce the apparent activation energy of the aminomagnesium-lithium hydride composite system, and improve the hydrogen release kinetics performance of the aminomagnesium-lithium hydride composite system. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The X-ray diffraction (XRD) spectrum of the aminomagnesium prepared for Example 1;

[0039] Figure 2 The temperature-variable hydrogen release curve diagram of the final product of Example 2 (labeled as SmN, CeN, NdN, PrN and LaN) and Comparative Example 1 (labeled as Pristine);

[0040] Figure 3Temperature-Dependent Hydrogen Absorption Curves of the Nitrogen-Containing Cerium Nitride-Containing Amino Magnesium-Lithium Hydride Composite Hydrogen Storage Material of Example 2 (labeled as x = 5) and the Raw Sample of Comparative Example 1 (labeled as x = 0);

[0041] Figure 4 Temperature-Dependent Hydrogen Absorption Curves of the Nitrogen-Containing Cerium Nitride-Containing Amino Magnesium-Lithium Hydride Composite Hydrogen Storage Material of Example 2 (labeled as x = 5) and the Raw Sample of Comparative Example 1 (labeled as x = 0);

[0042] Figure 5 Temperature-Dependent Hydrogen Absorption Curves of the Nitrogen-Containing Cerium Nitride-Containing Amino Magnesium-Lithium Hydride Composite Hydrogen Storage Material of Example 2 (labeled as x = 5) and the Raw Sample of Comparative Example 1 (labeled as x = 0). DETAILED DESCRIPTION

[0043] The present application is further described in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are intended to illustrate the present application and are not intended to limit the scope of the present application.

[0044] The operation methods in the following examples, for which no specific conditions are indicated, are generally performed according to conventional conditions, or according to the conditions recommended by the manufacturers.

[0045] Example 1

[0046] 4 g of magnesium powder was placed in a 150 mL ball mill tank with a high-pressure gas valve, and stainless steel milling balls were configured according to a ball-to-material ratio of 120: 1 (6 mm and 10 mm diameter stainless steel milling balls were used). After the ball mill tank was configured, it was vacuumed and then 7 bar of ammonia was introduced. Ammonia pressure high-energy ball milling was performed at 500 rpm for 10 h. After the ball milling, the gray-black powder was taken out and placed in a 200 mL high-pressure reactor with a high-pressure gas valve. After vacuuming, 7 bar of ammonia was introduced, and the reactor was kept at 300°C while ammonia was timely supplemented. After the ammonia pressure no longer decreased, the white powder was taken out, which was the amino magnesium. All powder loading and powder taking processes were completed under the protection of an argon atmosphere.

[0047] The XRD pattern of the white amino magnesium prepared in this example is shown in Figure 1 The diffraction results show that the phase composition of the white powder is single amino magnesium.

[0048] Example 2

[0049] The aminomagnesium and lithium hydride prepared in Example 1 were mixed and ground in a 1:2 molar ratio, for a total of 0.5 g; they were transferred into a ball mill pot, and stainless steel milling balls were arranged in a ball-to-material ratio of 120:1 (stainless steel milling balls of two diameters, 6 mm and 10 mm, were used). Ball milling was performed under 1 bar of argon at a rotation speed of 500 rpm for 36 h, using a batch ball milling procedure, with the mill being stopped every 5 min to allow the heat to dissipate. The final product was obtained, i.e. the aminomagnesium-lithium hydride composite hydrogen storage material containing the rare earth nitride of the original sample.

[0050] Comparative Example 1

[0051] The aminomagnesium and lithium hydride prepared in Example 1 were mixed and ground in a 1:2 molar ratio, for a total of 0.5 g; they were transferred into a ball mill pot, and stainless steel milling balls were arranged in a ball-to-material ratio of 120:1 (stainless steel milling balls of two diameters, 6 mm and 10 mm, were used). Ball milling was performed under 1 bar of argon at a rotation speed of 500 rpm for 36 h, using a batch ball milling procedure, with the mill being stopped every 5 min to allow the heat to dissipate. The final product was obtained, i.e. the aminomagnesium-lithium hydride composite hydrogen storage material containing the rare earth nitride of the original sample.

[0052] In the tests of the samples of Example 2 and Comparative Example 1, the initial dehydrogenation temperature of the samples containing lanthanum nitride, praseodymium nitride, samarium nitride or neodymium nitride was about 115°C, the initial dehydrogenation temperature of the sample containing cerium nitride was 105°C, and the initial dehydrogenation temperature of the original sample was 130°C, as shown in Table 1. Figure 2

[0053] In the tests of the samples of Example 2 and Comparative Example 1, the initial hydrogenation temperature of the sample containing cerium nitride was 70°C, and the initial hydrogenation temperature of the original sample was 110°C, as shown in Table 2. Figure 3

[0054] In the tests of the samples of Example 2 and Comparative Example 1, within 100 min, the sample containing cerium nitride released 2.13, 3.53, 4.02 and 4.34 wt% of hydrogen at 140, 150, 160 and 170°C, respectively, and the original sample released 0.93, 1.62, 3.27 and 3.87 wt% of hydrogen at 140, 150, 160 and 170°C, respectively, as shown in Table 3. Figure 4

[0055] ​​​In the sample testing of Example 2 and Comparative Example 1, the sample containing cerium nitride can absorb 2.53, 3.64, 4.45 and 4.71 wt% of hydrogen at 140, 150, 160 and 170°C, respectively, within 150 min, while the original sample can absorb 0.77, 1.39, 1.98 and 3.35 wt% of hydrogen at 140, 150, 160 and 170°C, respectively, within 150 min, as shown in Figure 5

[0056] It is to be understood, moreover, that the application is not limited to the particular examples described herein, but that various modifications and changes can be made thereto by those skilled in the art without departing from the scope of the present application, which is set forth in the appended claims.​

Claims

1. A rare earth nitride-containing aminomagnesium-lithium hydride composite hydrogen storage material, characterized in that, The rare earth nitride is at least one of SmN and NdN. The rare earth nitride is at least one of SmN and NdN.

2. The rare earth nitride-containing magnesium amide-lithium hydride composite hydrogen storage material according to claim 1, characterized in that The mass ratio of the rare earth nitride is not more than 10% in the total mass of the aminomagnesium-lithium hydride composite system and the rare earth nitride.

3. The rare earth nitride-containing magnesium amide-lithium hydride composite hydrogen storage material of claim 1, wherein, The molar ratio of aminomagnesium to lithium hydride in the aminomagnesium-lithium hydride composite system is 1:

2.

4. The method for producing a rare earth nitride-containing magnesium amide-lithium hydride composite hydrogen storage material according to any one of claims 1 to 3, characterized by, The aminomagnesium-lithium hydride composite hydrogen storage material containing the rare earth nitride is obtained by mixing aminomagnesium with lithium hydride, adding the rare earth nitride during the mixing, and transferring the mixed mixture into a ball mill tank for ball milling under inert gas protection.

5. The production method according to claim 4, characterized by, The parameters of the ball milling are as follows: the ball-to-material ratio is 110-130:1, stainless steel balls with diameters of 6 mm and 10 mm are used, the ball milling speed is 400-600 rpm, the ball milling time is 24-48 h, and an intermittent ball milling process is used.

6. Use of rare-earth nitrides for improving the hydrogen storage properties of the aminomagnesium-lithium hydride composite system, characterized in that, The rare earth nitride is at least one of SmN and NdN.

7. Use according to claim 6, characterized in that, The mass ratio of the rare earth nitride is not more than 10% in the total mass of the aminomagnesium-lithium hydride composite system and the rare earth nitride.

8. Use according to claim 6, characterized in that, The molar ratio of aminomagnesium to lithium hydride in the aminomagnesium-lithium hydride composite system is 1:2.

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