A metal hydride hydrogen storage material, its preparation method and its application

Abstract

This invention relates to the field of metal hydride hydrogen storage materials, and particularly to a metal hydride hydrogen storage material, its preparation method, and its applications. The method includes the following steps: First, using metal hydride and metallocene as starting materials; second, ball milling the materials in an Ar glove box; third, ball milling in a ball mill jar filled with a hydrogen atmosphere or an inert atmosphere. This invention provides a method for controlling the thermodynamics of metal hydrides. This method is simple, exhibits lower thermodynamic stability and better kinetic performance, making it promising for future applications. It allows control of the thickness of the surface coating layer, enabling thermodynamic / kinetic regulation of hydrogen absorption and desorption without affecting hydrogen transport. The preparation method is simple, requiring only high-energy ball milling to obtain the product. It effectively improves the hydrogen absorption / desorption performance of metal hydride materials and enables the development of a high-performance metal hydride hydrogen storage system, which can be widely applied in hydrogen fuel cell vehicles, hydrogen refueling stations, hydrogen purification and separation, and other fields.

Description

Technical fields:

[0001] This invention relates to the field of metal hydride hydrogen storage materials technology, and in particular to a metal hydride hydrogen storage material, its preparation method, and its application. Background technology:

[0002] Hydrogen, as an ideal energy and material carrier, boasts an energy density of up to 143 MJ kg⁻¹, three times that of gasoline. It is environmentally friendly, with zero emissions during its use and low carbon emissions throughout its entire lifecycle. Hydrogen storage and transportation, as a crucial link in the development and application of hydrogen energy, effectively connects production and consumption. Considering factors such as safety, storage conditions, actual storage capacity, theoretical storage potential, and production costs, solid-state hydrogen storage is the most promising and has the greatest development potential for large-scale hydrogen storage and transportation. The hydrogen absorption and desorption processes of metal hydride hydrogen storage materials are jointly controlled by thermodynamics and kinetics. The desorption reaction requires overcoming not only the thermodynamic barrier (ΔH) but also the kinetic energy barrier.

[0003] With the research on metal hydride hydrogen storage materials, existing technologies have provided a variety of metal hydride hydrogen storage materials, along with various preparation and modification methods, such as reaction destabilization, catalytic modification, nano-confining, and element substitution. Document CN110116990A discloses an in-situ preparation method for nano-magnesium hydride. This method involves placing magnesium chloride and lithium hydride in an organic solvent under an inert atmosphere, stirring to obtain an organic suspension of the mixture; ultrasonically treating the organic suspension to promote a chemical reaction in the mixture; filtering after the reaction; washing, centrifuging, and drying the solid reaction product to remove residual organic matter, yielding nano-magnesium hydride, which exhibits good hydrogen absorption and desorption performance. However, this preparation and modification method is relatively complex, making large-scale production difficult. The metal nitrogen-hydrogen system reported by Chen Ping et al. from the Dalian Institute of Chemical Physics, consisting of a composite hydrogen storage system composed of metal oxyides and hydrides, optimizes the thermodynamics of hydrogen absorption and desorption; however, the hydrogen desorption kinetics are poor, and the released gas contains a small amount of ammonia, severely hindering its practical application. In summary, despite the good progress made, many problems still exist: the hydrogen absorption and desorption temperatures are still relatively high and the kinetics are slow, resulting in poor cycling performance; the constructed unstable system is prone to introducing impurity gases, affecting the purity of hydrogen; the introduced stabilizer usually accounts for a large proportion of the mass, which significantly reduces the hydrogen storage capacity and seriously hinders the widespread application of hydride hydrogen storage materials. Summary of the Invention:

[0004] The purpose of this invention is to provide a metal hydride hydrogen storage material, its preparation method, and its application, in order to overcome the problems of existing technologies, such as complex processes, difficulty in large-scale production, high hydrogen absorption and desorption temperatures, slow kinetics, and poor reversibility.

[0005] To achieve the objectives of this invention, the technical solution provided by this invention is: a method for preparing a metal hydride hydrogen storage material, comprising the following steps:

[0006] Step 1: Using metal hydride and metallocene as starting materials, weigh them in an Ar gas glove box, wherein the mass of the metallocene accounts for 10-50% of the total mass of the two.

[0007] The second step is to place the weighed raw material into a stainless steel ball mill jar equipped with a gas valve in an Ar gas glove box. The ball milling speed is 100-500 r / min, the ball-to-material ratio is 10:1-200:1, and the time is 1-20 h.

[0008] The third step is to fill the ball mill jar with a hydrogen atmosphere or an inert atmosphere for ball milling at a pressure of 0.5 to 10 bar.

[0009] Furthermore, the aforementioned metal hydride is selected from one or more metal hydrides such as lithium hydride, magnesium hydride, and aluminum hydride.

[0010] Furthermore, the aforementioned dicelocene is selected from one or more of dicelocenes such as ferrocene, nickel, cobalt, and chromium.

[0011] Furthermore, the aforementioned dicelocene accounts for 10-50% of the total mass of both.

[0012] Furthermore, the ball milling speed is 100-500 r / min, the ball-to-material ratio is 10:1-500:1, and the time is 1-20 h.

[0013] Furthermore, the pressure of the atmosphere introduced into the above-mentioned ball mill jar is 0.5 to 10 bar.

[0014] Furthermore, the aforementioned inert atmosphere is selected from gases such as nitrogen and argon.

[0015] Furthermore, the above-mentioned method for preparing metal hydride hydrogen storage materials yields a metal hydride hydrogen storage material.

[0016] Furthermore, the aforementioned metal hydride hydrogen storage materials can be used as reusable hydrogen absorption / desorption materials.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. This invention provides a method for regulating the thermodynamics of metal hydrides. This method reduces the particle size of metal hydrides while simultaneously forming a highly dispersed carbonaceous material layer on the surface of the metal hydride, thus reducing the environmental sensitivity of the hydride. This coating layer can inhibit the aggregation and growth of hydride nanoparticles during subsequent hydrogen absorption and desorption, improving its cycle performance. The highly dispersed metal component can act as a catalyst to lower the dissociation barrier of hydrogen, enhancing the kinetic characteristics of the hydrogen storage material. This method is simple and is a way to achieve large-scale preparation and modification of hydrides. Using commercially available or self-made metal hydrides and metallocene as raw materials, the materials are crushed and mixed through optimized, easily controllable high-energy ball milling to prepare metal hydride hydrogen storage materials with a thermodynamically unstable state. The construction of the thermodynamically unstable system in the metal hydride material ensures that the hydride powder has a good morphology and significantly reduces its initial and peak hydrogen desorption temperatures, resulting in a significant improvement in hydrogen storage performance. Metal hydride materials with thermodynamic instability exhibit poorer thermodynamic stability and better kinetic performance compared to materials prepared by traditional methods due to changes in their reaction pathways, making them promising for future development and application.

[0019] 2. In this invention, the raw materials include a wide variety of metallocenes, which are easy and convenient to obtain. Their purpose in this invention is to act as a reaction destabilizer, regulating the hydrogen desorption pathway of hydrides, thereby improving the hydrogen absorption and desorption thermodynamics of metal hydrides. Simultaneously, adjusting the types of active centers in the metallocenes can lower the hydrogen dissociation energy barrier, thus enhancing the hydrogen absorption and desorption kinetics of the metal hydride hydrogen storage material. By optimizing the metallocene content, this invention can control the thickness of the surface coating layer, achieving thermodynamic / kinetic regulation of hydrogen absorption and desorption without affecting hydrogen transport.

[0020] 3. The preparation method provided in this application is simple, and the product can be obtained solely through high-energy ball milling, making it suitable for large-scale industrial production. Optimizing the ball-to-material ratio and grinding time in the ball milling process controls the uniformity of the mixture of metallocene and metal hydride, the particle size of the metal hydride, and the thickness and uniformity of the surface coating. The preparation method of this invention promotes the thermodynamic instability of the metal hydride hydrogen storage material, effectively improving the hydrogen absorption / desorption performance of the metal hydride material.

[0021] 4. This invention improves the problems of high hydrogen desorption temperature, slow hydrogen absorption and desorption rate, and poor cycle reversibility of metal hydride hydrogen storage materials by constructing a "reaction instability" system and regulating metal hydride hydrogen storage materials through thermodynamics and kinetics. It realizes the development of a high-performance metal hydride hydrogen storage system, which can be widely used in hydrogen fuel cell vehicles, hydrogen refueling stations, hydrogen purification and separation and other fields. Attached image description:

[0022] Figure 1 This is a schematic diagram of the preparation method of the present invention;

[0023] Figure 2 (a) and (b) are SEM images of lithium hydride with 20 wt% ferrocene added, (c) is the XRD pattern of lithium hydride with 20 wt% ferrocene added and original lithium hydride, and (d) is the non-isothermal dehydrogenation curve of lithium hydride with 20 wt% ferrocene added and original lithium hydride.

[0024] Figure 3 The images are SEM and EDS images of lithium hydride with 45 wt% ferrocene added.

[0025] Figure 4 The XRD patterns of lithium hydride with 45 wt% ferrocene added and original lithium hydride are shown.

[0026] Figure 5 The non-isothermal hydrogen desorption curves are of lithium hydride with 45 wt% ferrocene added and original lithium hydride.

[0027] Figure 6 (a) and (b) are SEM images of lithium hydride with 20 wt% nickel-cadmium added, (c) is the XRD pattern of lithium hydride with 20 wt% nickel-cadmium added and original lithium hydride, and (d) is the non-isothermal dehydrogenation curve of lithium hydride with 20 wt% nickel-cadmium added and original lithium hydride.

[0028] Figure 7 The images are SEM and EDS images of lithium hydride with 45 wt% nickel dicerocene added.

[0029] Figure 8 The XRD patterns of lithium hydride with 45 wt% nickel-cadmium added and original lithium hydride are shown.

[0030] Figure 9 The non-isothermal hydrogen desorption curves are of lithium hydride with 45 wt% nickel-cadmium added and original lithium hydride.

[0031] Figure 10 (a) and (b) are SEM images of lithium hydride with 20 wt% cobalt-1, (c) is the XRD pattern of lithium hydride with 20 wt% cobalt-1 and original lithium hydride, and (d) is the non-isothermal dehydrogenation curve of lithium hydride with 20 wt% cobalt-1 and original lithium hydride.

[0032] Figure 11 The images are SEM and EDS images of lithium hydride with 45 wt% cobalt-1,000 added.

[0033] Figure 12 The XRD patterns of lithium hydride with 45 wt% cobalt-1,4-diocene added and original lithium hydride are shown.

[0034] Figure 13The non-isothermal hydrogen desorption curves are of lithium hydride with 45 wt% cobalt-1,000 added and original lithium hydride.

[0035] Figure 14 This is a temperature-varying mass spectrum of lithium hydride with 45 wt% cobalt-1,000 added.

[0036] Figure 15 The hydrogen deactivation activation energy is fitted based on the Kirssinger method using DSC curves. Detailed implementation method:

[0037] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] See Figure 1 The design concept of this invention is as follows: The method for constructing the unstable system of metal hydride hydrogen storage material adopts ball milling. Metal hydride and metallocene are mixed by ball milling. By controlling the feeding ratio, the type of metallocene, and the ball milling conditions, different metal hydride / metallocene composite hydrogen storage materials can be obtained.

[0039] Example 1: A method for preparing a metal hydride hydrogen storage material, the specific steps of which are as follows: weigh 0.8g of lithium hydride and 0.2g of ferrocene, and mechanically ball-mill them for 2 hours under argon protection, wherein the argon pressure is 0.8Mpa, the ball-to-material ratio is 150:1, and the rotation speed is 500rpm. After ball milling is completed, the lithium hydride / ferrocene composite hydrogen storage material can be obtained.

[0040] See Figure 2 The scanning images (a) and (b) show that the size of the lithium hydride particles ranges from approximately 200 nm to 2 μm. See [link to image]. Figure 2 c. After ball milling, the peak intensity of LiH in all samples decreased significantly, while the peak width increased. This is likely due to LiH defects, amorphization, and reduced particle size caused by the high-energy impact during ball milling. See also Figure 2 c. Hydrogen absorption and desorption experiments showed that when 20 wt% ferrocene was added, the initial hydrogen desorption temperature decreased to 270℃, and a small plateau appeared between 534℃ and 600℃, at which point the amount of hydrogen desorption was about 1.47 wt%. After 600℃, a large amount of hydrogen desorption began to occur again, with a total amount of hydrogen desorption of 6.92 wt%.

[0041] Example 2: A method for preparing a metal hydride hydrogen storage material, the specific steps of which are as follows:

[0042] Weigh 0.55g of lithium hydride and 0.45g of ferrocene, and mechanically ball-mill for 2 hours under argon protection. The argon pressure is 0.8MPa, the ball-to-material ratio is 150:1, and the rotation speed is 500rpm. After ball milling, the lithium hydride / ferrocene composite hydrogen storage material can be obtained.

[0043] See Figure 3Scanning images show that lithium hydride particles are approximately 200 nm to 1 μm in size. Elemental surface scans show that iron is uniformly distributed with no obvious aggregation. See also Figure 4 As can be seen, the dimacro diffraction peaks have significantly broadened and weakened. (See also...) Figure 5 Hydrogen absorption and desorption experiments showed that with the addition of 45 wt% ferrocene, the initial hydrogen desorption temperature was 265℃, with no obvious hydrogen desorption plateau (only a small hydrogen desorption plateau existed between 502℃ and 552℃, with a hydrogen desorption amount of approximately 1.8 wt%), and the total hydrogen desorption amount was 5.71 wt%. See also Figure 15 The hydrogen deactivation activation energy of the system was reduced to 157.55 ± 14.78 KJ / mol after the addition of 45 wt% ferrocene.

[0044] Example 3: A method for preparing a metal hydride hydrogen storage material, the specific steps of which are as follows:

[0045] Weigh 0.8g of lithium hydride and 0.2g of nickel dicerocene, and mechanically ball-mill for 2 hours under argon protection. The argon pressure is 0.8 MPa, the ball-to-material ratio is 150:1, and the rotation speed is 500 rpm. After ball milling, the lithium hydride / nickel dicerocene composite hydrogen storage material can be obtained.

[0046] See Figure 6 Scanning images (a) and (b) show that the size of the lithium hydride particles ranges from approximately 200 nm to 2 μm. See also Figure 6 The c-NiCrO diffraction pattern showed significant broadening and weakening, with two distinct peaks at 16.9° and 24.7°, indicating that a reaction occurred between LiH and NiCrO during high-energy ball milling, forming an amorphous carbonaceous material layer on the LiH surface. (See also...) Figure 6 (d) Hydrogen absorption and desorption experiments showed that when 20 wt% nickel dicerocene was added, the initial hydrogen desorption temperature decreased to 256 °C. The first plateau appeared between 384 °C and 444 °C, at which point the hydrogen desorption amount was about 1.83 wt%. The second plateau appeared between 447 °C and 640 °C, at which point the hydrogen desorption amount was about 2.17 wt%. After 640 °C, a large amount of hydrogen was released again, with a total hydrogen desorption amount of 6.39 wt%.

[0047] Example 4: A method for preparing a metal hydride hydrogen storage material, the specific steps of which are as follows:

[0048] Weigh 0.55g of lithium hydride and 0.45g of nickel dicerocene, and mechanically ball-mill for 2 hours under argon protection. The argon pressure is 0.8 MPa, the ball-to-material ratio is 150:1, and the rotation speed is 500 rpm. After ball milling, the lithium hydride / nickel dicerocene composite hydrogen storage material can be obtained.

[0049] See Figure 7The scanning images show a significant reduction in the size of lithium hydride particles, approximately below 200 nm, with particles of about tens of nanometers adhering to the particle surface. (See also...) Figure 8 As can be seen, the nickel-cadmium diffraction pattern exhibits significant broadening and weakening, with two distinct peaks appearing at 16.9° and 24.7°. This indicates that during the high-energy ball milling process, LiH and nickel-cadmium undergo some kind of reaction, forming an amorphous carbonaceous material layer on the LiH surface. (See also...) Figure 9 Hydrogen absorption and desorption experiments showed that with the addition of 45 wt% nickel dicerocene, the initial hydrogen desorption temperature was 230℃, with a clear hydrogen desorption plateau between 500℃ and 680℃. The amount of hydrogen desorbed was approximately 3.72 wt%, and the total hydrogen desorption was 4.83 wt%. (See also...) Figure 15 The hydrogen deactivation activation energy of the system was reduced to 132.02 ± 38.74 KJ / mol after the addition of 45 wt% nickel dicerocene.

[0050] Example 5: A method for preparing a metal hydride hydrogen storage material, the specific steps of which are as follows:

[0051] Weigh 0.8g of lithium hydride and 0.2g of cobalt cadmium, and mechanically ball-mill for 2 hours under argon protection. The argon pressure is 0.8 MPa, the ball-to-material ratio is 150:1, and the rotation speed is 500 rpm. After ball milling, the lithium hydride / cobalt cadmium composite hydrogen storage material can be obtained.

[0052] See Figure 10 The scanning images (a) and (b) show that the lithium hydride particles have a visible size of approximately 200 nm. See also... Figure 10 The cobalt-2,4-diocene diffraction pattern showed significant broadening and weakening, with two distinct peaks at 16.9° and 24.7°, indicating that a reaction occurred between LiH and cobalt-2,4-diocene during high-energy ball milling, forming an amorphous carbonaceous material layer on the LiH surface. (See also...) Figure 10 The hydrogen absorption and desorption experiments showed that when 20 wt% cobalt dicene was added, the initial hydrogen desorption temperature decreased to 270℃, and a long and gentle plateau appeared between 327℃ and 548℃, at which point the amount of hydrogen desorption was about 2.16 wt%. After 727℃, a large amount of hydrogen desorption began to occur again, with a total amount of hydrogen desorption of 6 wt%.

[0053] Example 6: A method for preparing a metal hydride hydrogen storage material, the specific steps of which are as follows:

[0054] Weigh 0.55g of lithium hydride and 0.45g of cobalt cadmium, and mechanically ball-mill for 2 hours under argon protection. The argon pressure is 0.8 MPa, the ball-to-material ratio is 150:1, and the rotation speed is 500 rpm. After ball milling, the lithium hydride / cobalt cadmium composite hydrogen storage material can be obtained.

[0055] See Figure 11Scanned images show that the lithium hydride particles are smaller than 200 nm, with particles of about tens of nanometers attached to the surface, indicating greater particle dispersion. (See [link to image]). Figure 12 Elemental surface scanning showed that cobalt was uniformly distributed with no obvious aggregation. (See also...) Figure 13 Hydrogen absorption and desorption experiments showed that with the addition of 45 wt% cobalt-1, the initial hydrogen desorption temperature was 210 °C, with a clear hydrogen desorption plateau between 359 °C and 773 °C. The amount of hydrogen desorbed was approximately 4.72 wt%, and the total hydrogen desorption was 5.02 wt%. (See also...) Figure 14 Online mass spectrometry analysis revealed that only hydrogen gas was produced within a temperature range of 500°C, proving that the unstable system constructed in this invention does not generate any impurity gases. See also... Figure 15 The hydrogen deactivation activation energy of the system was reduced to 78.89 ± 20.53 KJ / mol after adding 45 wt% cobalt dicene.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method of preparing a metal hydride hydrogen storage material, characterized by: The method comprises the following steps: First step, weighing the starting reactants of metal hydride and metallocene in an Ar glove box, the mass of the metallocene accounts for 20% of the total mass of the two; Second step, placing the weighed starting materials in a stainless steel ball mill tank with a gas valve in an Ar glove box, the rotation speed of the ball mill is 100-500 r / min, the ball-to-material ratio is 10:1-200:1, and the time is 1-20 h; Third step, ball milling in an inert atmosphere in the ball mill tank, the pressure is 0.5-10 bar; The metallocene is selected from ferrocene; The metal hydride is selected from lithium hydride; The inert atmosphere is selected from argon.

2. A metal hydride hydrogen storage material obtained by the method for preparing a metal hydride hydrogen storage material according to claim 1.

3. Application of the metal hydride hydrogen storage material according to claim 2 as a repeatable hydrogen absorption / desorption material.

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