Hydrogen storage alloy composite material and preparation method thereof

Abstract

The invention relates to a hydrogen storage alloy composite material and a preparation method thereof.The preparation method comprises the following steps that S1, hydrogen storage alloy powder, an organic solvent and a coating layer raw material are in contact and subjected to ball milling treatment, and a first product is obtained; the coating layer raw material comprises a first metal source and a first organic ligand, or the coating layer raw material comprises an MOF material; and S2, optionally, carrying out roasting carbon deposition treatment on the first product. According to the preparation method provided by the invention, the air poisoning resistance of the hydrogen storage alloy material can be improved.

Description

Technical Field

[0001] This disclosure relates to the field of hydrogen storage material preparation technology, specifically to a hydrogen storage alloy composite material and its preparation method. Background Technology

[0002] Hydrogen storage alloys are a type of hydrogen storage material with a long development history and high potential for practical application, characterized by rapid hydrogen absorption and desorption rates and a wide adjustable range of absorption and desorption pressures. However, hydrogen storage alloys are easily oxidized in air, so improving their functionalization and enhancing their oxidation resistance has been a research hotspot for many years both domestically and internationally.

[0003] Regarding the issue of air poisoning in hydrogen storage alloys, recent researchers have modified the outer surface of these alloys to improve their oxidation resistance through specific functional improvements. Lv et al. (Chemical Physics Letters, 2020, 754, 137697) coated the alloy surface with antioxidant metals such as Cu through ball milling and elemental substitution reactions. Their study found that the copper coating on the alloy surface had a beneficial effect on the electrochemical performance of Co2B alloys, improving their electrochemical hydrogen storage performance. However, according to the SEM images provided in the aforementioned article, the distribution of Cu on the material surface was not uniform, and the surface-loaded Cu content was relatively low. These issues limit the large-scale industrial application of this method.

[0004] Existing technologies utilize carbon to coat and modify hydrogen storage alloys, functionalizing the material surface. However, from an elemental distribution perspective, carbon cannot be uniformly dispersed and covered on the surface of hydrogen storage alloys. Since most hydrogen storage alloys are micron-sized materials, further research is needed to completely and uniformly cover the alloy surface with carbon. Furthermore, the thickness of the carbon coating on the surface also needs attention, as surface loading with carbon can affect the hydrogen storage rate of the composite material. Therefore, further in-depth research is required to improve the material's resistance to air poisoning while maintaining a certain hydrogen storage rate. Summary of the Invention

[0005] The purpose of this disclosure is to provide a hydrogen storage alloy composite material and its preparation method to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing hydrogen storage alloy composite materials, comprising the following steps: S1. Contact the hydrogen storage alloy powder, organic solvent and coating material, and perform ball milling to obtain a first product; wherein the coating material includes a first metal source and a first organic ligand, or the coating material includes MOF material; S2. Optionally, the first product is subjected to calcination and carbonization treatment.

[0007] Optionally, the coating material includes a first metal source and a first organic ligand: The first metal source is selected from one or more of zinc salts, cobalt salts, copper salts, and magnesium salts; optionally, the zinc salt is selected from one or more of zinc acetate, zinc chloride, and zinc nitrate; the cobalt salt is selected from one or more of cobalt acetate, cobalt chloride, and cobalt nitrate; the copper salt is selected from one or more of copper acetate, copper chloride, and copper nitrate; and the magnesium salt is selected from one or more of magnesium acetate, magnesium chloride, and magnesium nitrate. Optionally, the first organic ligand is selected from one or more of dimethylimidazole, azirethylcarbazole, dimethylpyridine, terephthalic acid, and toluene; Preferably, the first metal source is selected from one or more zinc salts, more preferably zinc acetate; the first organic ligand includes dimethylimidazole.

[0008] Optionally, the coating material includes MOF material: The MOF material contains a second metallic element and a second organic ligand; Preferably, the second metallic element is selected from one or more of cobalt, zinc, copper, and magnesium; The second organic ligand moiety is selected from one or more of dimethylimidazolium, azirethylcarbazole, dimethylpyridine, terephthalic acid, and toluene; More preferably, based on the total weight of the MOF material, the content of the second metal element is 2-45% by weight, and the content of the second organic ligand is 55-98% by weight; preferably, the content of the metal portion is 10-30% by weight, and the content of the second organic ligand is 70-90% by weight.

[0009] Optionally, the hydrogen storage alloy powder is selected from one or more of titanium-based hydrogen storage alloys, rare earth-based hydrogen storage alloys, vanadium-based hydrogen storage alloys, and magnesium-based hydrogen storage alloys; preferably, it is a titanium-based hydrogen storage alloy. Optionally, the particle size of the hydrogen storage alloy powder is 0.05~200μm, preferably 0.2~10μm; Optionally, the organic solvent is selected from one or more of methanol, isopropanol, ethanol and diethyl ether, preferably methanol.

[0010] Optionally, based on the total weight of the hydrogen storage alloy powder, the first metal source, and the first organic ligand, the content of the hydrogen storage alloy powder is 60-98% by weight, the content of the first metal source is 1-20% by weight, and the content of the first organic ligand is 1-20% by weight; preferably, the content of the hydrogen storage alloy powder is 80-96% by weight, the content of the first metal source is 2-10% by weight, and the content of the first organic ligand is 2-10% by weight. Alternatively, based on the total weight of the hydrogen storage alloy powder and the MOF material, the content of the hydrogen storage alloy powder is 60-98% by weight, and the content of the MOF material is 2-40% by weight; preferably, the content of the hydrogen storage alloy is 80-96% by weight, and the content of the MOF material is 4-20% by weight.

[0011] Optionally, the conditions for ball milling include: a solid-liquid ratio of 1:2 to 50, preferably 1:5 to 25; a ball milling speed of 200 to 400 rpm, preferably 300 to 400 rpm; a ball milling time of 2 to 20 h, preferably 10 to 16 h; and a ball-to-material ratio of 10 to 50:1, preferably 25 to 35:1.

[0012] Optionally, in step S2, the conditions for the calcination carbonization treatment include: a calcination temperature of 400~1000℃ and a calcination time of 0.5~8h; preferably, a calcination temperature of 700~900℃ and a calcination time of 0.5~6h; and the calcination atmosphere is selected from one or more of argon, nitrogen and air.

[0013] Optionally, the method further includes: The first product is subjected to solid-liquid separation treatment, and the resulting solid product is dried; then the calcination and carbonization treatment is performed. Optionally, the solid-liquid separation process includes centrifugation. Preferably, the centrifugation conditions include: a centrifugation speed of 5000~9500 rpm and a centrifugation time of 4~15 min. The drying conditions include: a vacuum drying temperature of 40~80℃ and a vacuum drying time of 5~12h; preferably, the vacuum drying temperature is 60~75℃ and the vacuum drying time is 6~10h.

[0014] The second aspect of this disclosure provides a hydrogen storage alloy composite material prepared according to the method described in the first aspect of this disclosure.

[0015] Optionally, the hydrogen storage alloy composite material includes a hydrogen storage alloy core and a carbon coating layer; Preferably, based on the total weight of the hydrogen storage alloy composite material, the content of the hydrogen storage alloy core is 80-98% by weight, and the content of the carbon coating layer is 2-20% by weight. More preferably, the content of the hydrogen storage alloy core is 90-98% by weight, and the content of the carbon coating layer is 2-10% by weight. Optionally, the carbon coating layer comprises carbon and elemental metals; preferably, based on the total weight of carbon and elemental metals in the carbon coating layer, the carbon content is 75-99% by weight and the elemental metal content is 1-25% by weight; preferably, the carbon content is 90-99% by weight and the elemental metal content is 1-10% by weight.

[0016] Optionally, the particle size of the hydrogen storage alloy composite material is 0.05~200μm, preferably 0.2~10μm; The thickness of the carbon coating layer is 1~1000nm, preferably 5~50nm.

[0017] Through the above technical solutions, this disclosure provides a hydrogen storage alloy composite material and its preparation method. The ball milling process effectively accelerates the in-situ crystallization rate, improves the in-situ coating effect of the coating material on the surface of the hydrogen storage alloy powder, and promotes the in-situ growth of the first metal source and the first organic ligand on the surface of the hydrogen storage alloy powder. It also enables the MOF material to cover the surface of the hydrogen storage alloy powder more uniformly, resulting in a first product with a carbon layer precursor. Then, optionally, a carbonization treatment is performed to obtain a carbon coating layer. The carbon elements can be more uniformly dispersed on the surface of the hydrogen storage alloy, avoiding the uneven dispersion of carbon elements on the alloy surface that occurs with single ball milling. This disclosure also modifies the hydrogen storage alloy material to improve its resistance to air oxidation, thus enhancing its resistance to air poisoning. Furthermore, the preparation method provided by this disclosure does not introduce water molecules to poison the hydrogen storage alloy material. In the hydrogen storage alloy composite material provided in this disclosure, the carbon-loaded hydrogen storage material (in the carbon coating layer and the hydrogen storage alloy material) can block oxygen from contacting the alloy surface. In addition to resisting air oxidation, the carbon element can also slow down the rate at which hydrogen passes through the material surface. Furthermore, in this hydrogen storage alloy composite material, the loaded carbon element does not affect hydrogen permeation within a certain range, while promoting hydrogen diffusion inside the alloy. This slows down the microcracks and alloy pulverization caused by volume shrinkage during hydrogen dehydrogenation and volume expansion during hydrogen absorption during the hydrogen absorption-dehydrogenation cycle. It also reduces grain boundary migration and grain growth caused by the hydrogen absorption-dehydrogenation heat effect, thereby improving the hydrogen dehydrogenation performance of the material.

[0018] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 These are XRD images of the hydrogen storage alloy composite materials obtained in Examples 1, 2, 3, 4, 5, and Comparative Example 1 after being exposed to air for 0 hours. Figure 2 These are XRD images of the hydrogen storage alloy composite materials obtained in Examples 1, 2, 3, 4, 5, and Comparative Example 1 after being exposed to air for 168 hours. Figure 3 These are SEM mapping elemental analysis test images of the hydrogen storage alloy composite material obtained in Example 1 after 0 hours of air exposure; Figure 4 These are SEM mapping elemental analysis test images of the hydrogen storage alloy composite material obtained in Example 2 after 0 hours of air exposure; Figure 5 These are SEM mapping elemental analysis test images of the hydrogen storage alloy composite material obtained in Example 3 after 0 hours of air exposure; Figure 6 These are SEM mapping elemental analysis test images of the hydrogen storage alloy composite material obtained in Example 4 after 0 hours of air exposure; Figure 7 This is a SEM mapping elemental analysis image of the hydrogen storage alloy composite material obtained in Example 5 after 0 hours of air exposure; Figure 8 This is a SEM mapping elemental analysis image of the hydrogen storage alloy composite material obtained in Example 1 after 168 hours of air exposure; Figure 9 These are SEM mapping elemental analysis test images of the hydrogen storage alloy composite material obtained in Example 2 after 168 hours of air exposure; Figure 10 These are SEM mapping elemental analysis test images of the hydrogen storage alloy composite material obtained in Example 3 after 168 hours of air exposure; Figure 11 This is a SEM mapping elemental analysis image of the hydrogen storage alloy composite material obtained in Example 4 after 168 hours of air exposure; Figure 12 This is a SEM mapping elemental analysis image of the hydrogen storage alloy composite material obtained in Example 5 after 168 hours of air exposure; Figure 13The image shows the SEM mapping elemental analysis test image of the hydrogen storage alloy composite material obtained in Comparative Example 1 after 168 hours of air exposure. Figure 14 These are the hydrogen storage kinetic performance curves of the hydrogen storage alloy composite materials obtained in Examples 1-5 and Comparative Example 1 after being exposed to air for 168 hours; Figure 15 This is a line scan distribution map of the hydrogen storage alloy composite material obtained in Example 1; Figure 16 These are SEM images and mapping elemental distribution diagrams of the hydrogen storage alloy composite material obtained in Example 6 after being exposed to air for 0 hours. Figure 17 These are SEM images and mapping elemental distribution diagrams of the hydrogen storage alloy composite material obtained in Example 7 after being exposed to air for 0 hours. Figure 18 These are SEM images and mapping elemental distribution diagrams of the hydrogen storage alloy composite material obtained in Example 8 after exposure to air for 0 hours. Figure 19 These are SEM images and mapping elemental distribution diagrams of the hydrogen storage alloy composite material obtained in Example 12 after being exposed to air for 0 hours. Figure 20 These are XRD images of the hydrogen storage alloy composite materials obtained in Examples 1, 6, 7, 12 and Comparative Example 1 after exposure to air for 0 hours; Figure 21 These are XRD images of the hydrogen storage alloy composite materials obtained in Examples 1, 6, 7, 8, 12 and Comparative Example 1 after 168 hours of exposure to air; Figure 22 These are SEM images and mapping elemental distribution diagrams of the hydrogen storage alloy composite material obtained in Example 6 after 168 hours of exposure to air; Figure 23 These are SEM images and mapping elemental distribution diagrams of the hydrogen storage alloy composite material obtained in Example 7 after 168 hours of exposure to air; Figure 24 These are SEM images and mapping elemental distribution diagrams of the hydrogen storage alloy composite material obtained in Example 12 after 168 hours of exposure to air; Figure 25 These are the hydrogen storage kinetic curves of the hydrogen storage alloy composite materials obtained in Examples 1, 12 and Comparative Example 1 after 0 hours of exposure to air; Figure 26 These are the hydrogen storage kinetic curves of the hydrogen storage alloy composite materials obtained in Examples 1, 12 and Comparative Example 1 after 168 hours of exposure to air. Detailed Implementation

[0020] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0021] The first aspect of this disclosure provides a method for preparing hydrogen storage alloy composite materials, comprising the following steps: S1. Contact the hydrogen storage alloy powder, organic solvent and coating material, and perform ball milling to obtain a first product; wherein the coating material includes a first metal source and a first organic ligand, or the coating material includes MOF material; S2. Optionally, the first product is subjected to calcination and carbonization treatment.

[0022] This disclosure provides a method for preparing hydrogen storage alloy composite materials. The ball milling process effectively accelerates the in-situ crystallization rate, improves the in-situ coating effect of the coating material on the surface of the hydrogen storage alloy powder, and promotes the in-situ growth of the first metal source and the first organic ligand on the surface of the hydrogen storage alloy powder. It also enables a more uniform coverage of the MOF material on the surface of the hydrogen storage alloy powder, resulting in a first product with a carbon layer precursor. Then, optionally, a carbonization treatment is performed to obtain a carbon coating layer. The carbon elements are more uniformly dispersed on the surface of the hydrogen storage alloy, avoiding the uneven dispersion of carbon elements on the alloy surface that occurs with single ball milling. This disclosure also modifies the hydrogen storage alloy material to improve its resistance to air oxidation, thus enhancing its resistance to air poisoning. Furthermore, the preparation method provided by this disclosure does not introduce water molecules to poison the hydrogen storage alloy material. In the hydrogen storage alloy composite material provided in this disclosure, the carbon-loaded hydrogen storage material (in the carbon coating layer and the hydrogen storage alloy material) can block oxygen from contacting the alloy surface. In addition to resisting air oxidation, the carbon element can also slow down the rate at which hydrogen passes through the material surface. Furthermore, in this hydrogen storage alloy composite material, the loaded carbon element does not affect hydrogen permeation within a certain range, while promoting hydrogen diffusion inside the alloy. This slows down the microcracks and alloy pulverization caused by volume shrinkage during hydrogen dehydrogenation and volume expansion during hydrogen absorption during the hydrogen absorption-dehydrogenation cycle. It also reduces grain boundary migration and grain growth caused by the hydrogen absorption-dehydrogenation heat effect, thereby improving the hydrogen dehydrogenation performance of the material.

[0023] This disclosure allows for the formation of two types of carbon coating precursors on the surface of hydrogen storage alloy powder by combining hydrogen storage alloy powder with two types of coating raw materials. Specifically, a first metal source and a first organic ligand can be used to generate a metal-organic framework material in situ on the surface of the hydrogen storage alloy powder as a carbon coating precursor, or a MOF material can be directly used to form a MOF material carbon coating precursor on the surface of the hydrogen storage alloy powder.

[0024] In the first embodiment, when the coating layer material includes a first metal source and a first organic ligand: The first metal source is selected from one or more of zinc salts, cobalt salts, copper salts, and magnesium salts; preferably, it is selected from one or more of zinc salts. Optionally, the zinc salt is selected from one or more of zinc acetate, zinc chloride, and zinc nitrate; The cobalt salt is selected from one or more of cobalt acetate, cobalt chloride, and cobalt nitrate; The copper salt is selected from one or more of copper acetate, copper chloride, and copper nitrate; The magnesium salt is selected from one or more of magnesium acetate, magnesium chloride, and magnesium nitrate.

[0025] In a preferred embodiment, the first organic ligand is selected from one or more of dimethylimidazole, azirethylcarbazole, dimethylpyridine, terephthalic acid, and toluene. The first organic ligand provided in this embodiment exhibits good coating ability when the first metal is in situ coated onto the surface of the hydrogen storage alloy powder, resulting in a suitable loading thickness on the alloy surface, and is easy to prepare.

[0026] This disclosure enables the in-situ growth of carbon coating precursors on the surface of hydrogen storage alloy powder by subjecting the first metal source and the first organic ligand to high-intensity mechanical ball milling. These precursors include, but are not limited to, zeolite imidazole ester framework materials (ZIF-8), cobalt dimethylimidazolium (ZIF-67), and MOF-74 microporous mesoporous metal-organic frameworks. Furthermore, the carbon coating precursors are uniformly coated on the surface of the hydrogen storage alloy powder, which is beneficial to improving the coating effect of the carbon coating layer in the final product.

[0027] In a more preferred embodiment, the first metal source is selected from one or more zinc salts, more preferably zinc acetate, and the first organic ligand includes dimethylimidazole. Zeolite imidazole ester framework material (ZIF-8) can be grown in situ on the surface of hydrogen storage alloy powder using zinc salt and dimethylimidazole. Zinc salt and dimethylimidazole have high solubility in organic solvents and readily form an organometallic framework structure. Furthermore, the inventors of this disclosure have found that existing ZIF-8 material preparation processes have low yields and demanding preparation conditions, making large-scale production impossible, or requiring high-temperature conditions and long preparation cycles. In contrast, the ZIF-8 material generated in situ using the method of this disclosure can be produced at room temperature. Compared to previous hydrothermal methods, the method of this disclosure does not introduce poisoning materials such as water molecules, and ZIF-8 material can be generated on the surface of the hydrogen storage alloy in a shorter preparation time (e.g., within 10 hours), significantly reducing the time required for ZIF-8 generation.

[0028] In the second embodiment, when the coating material includes MOF material: The MOF material contains a second metallic element and a second organic ligand; this disclosure directly uses MOF material and hydrogen storage alloy powder to ball mill to form a carbon coating precursor, which can also achieve a good coating effect on the surface of the hydrogen storage alloy.

[0029] In one specific embodiment, the second metallic element is selected from one or more of cobalt, zinc, copper, and magnesium; The second organic ligand moiety is selected from one or more of dimethylimidazole, azirethylcarbazole, dimethylpyridine, terephthalic acid, and toluene.

[0030] In one specific embodiment, the MOF material may have structures such as ZIF-8, ZIF-67, and MOF-7, and can be prepared by conventional methods.

[0031] In a preferred embodiment, based on the total weight of the MOF material, the content of the second metal element is 2-45% by weight, and the content of the second organic ligand is 55-98% by weight; preferably, the content of the metal portion is 10-30% by weight, and the content of the second organic ligand is 70-90% by weight. Ball milling the MOF material with the component contents of this embodiment yields a composite material product with better resistance to air poisoning. This product can both prevent poisoning gases from entering the hydrogen storage alloy and accelerate the entry of hydrogen into the alloy for storage.

[0032] In one specific embodiment, the hydrogen storage alloy powder is selected from one or more of titanium-based hydrogen storage alloys, rare earth-based hydrogen storage alloys, vanadium-based hydrogen storage alloys, and magnesium-based hydrogen storage alloys; preferably, it is a titanium-based hydrogen storage alloy; optionally, the particle size of the hydrogen storage alloy powder is 5~200μm, preferably 50~100μm.

[0033] In one specific embodiment, the organic solvent is selected from one or more of methanol, isopropanol, ethanol and diethyl ether, preferably methanol. On the one hand, methanol has a low boiling point and is easy to dry and remove; on the other hand, methanol helps to generate coating materials such as ZIF-8 in situ.

[0034] In a preferred embodiment, when the coating material includes a first metal source and a first organic ligand: based on the total weight of the hydrogen storage alloy powder, the first metal source, and the first organic ligand, the content of the hydrogen storage alloy powder can be 60-98% by weight, including but not limited to 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or any two of these values; the content of the first metal source can be 1-20% by weight, including but not limited to 1%, 4%, 8%, 12%, 16%, 20%, or any two of these values; the content of the first organic ligand can be 1-20% by weight, including but not limited to 1%, 4%, 8%, 12%, 16%, 20%, or any two of these values. Preferably, the content of the hydrogen storage alloy powder is 80-96% by weight, the content of the first metal source is 2-10% by weight, and the content of the first organic ligand is 2-10% by weight. By preparing the composite material according to the raw material ratio in this embodiment, a composite material with superior antioxidant properties can be obtained.

[0035] In another embodiment, when the coating material includes MOF material: based on the total weight of the hydrogen storage alloy powder and the MOF material, the content of the hydrogen storage alloy powder can be 60-98% by weight, including but not limited to 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or any two of these values; the content of the MOF material can be 2-40% by weight, including but not limited to 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any two of these values; preferably, the content of the hydrogen storage alloy is 80-96% by weight, and the content of the MOF material is 4-20% by weight. By preparing the composite material according to the raw material ratio in this embodiment, a composite material with superior antioxidant properties can be obtained.

[0036] In a preferred embodiment, the conditions for ball milling include: a solid-liquid ratio of 1:2 to 50 (including but not limited to 1:2, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:15, 1:20, or any two values), preferably 1:5 to 25; a ball milling speed of 200 to 400 rpm (including but not limited to 200 rpm, 300 rpm, 400 rpm), preferably 300 to 400 rpm; a ball milling time of 2 to 20 hours (including but not limited to 2 hours, 5 hours, 10 hours, 15 hours, 20 hours, or any two values), preferably 20 to 16 hours; and a ball-to-material ratio of 10 to 50:1 (including but not limited to 10:1, 20:1, 30:1, 40:1, 50:1, or any two values), preferably 25 to 35:1. By performing the ball milling reaction under the conditions of the high-intensity ball milling treatment in this embodiment, a more uniform in-situ reaction effect or a more uniform in-situ coating effect can be obtained, resulting in a composite material with better antioxidant properties.

[0037] In one embodiment, the conditions for the sintering and carbonization treatment in step S2 include: a sintering temperature of 400~1000℃ (including but not limited to 400℃, 600℃, 750℃, 800℃, 900℃, 1000℃ or any two values), and a sintering time of 0.5~8h (including but not limited to 0.5h, 1h, 2h, 4h, 6h, 8h or any two values); preferably, the sintering temperature is 700~900℃, and the sintering time is 0.5~6h; the sintering atmosphere is selected from one or more of argon, nitrogen, and air. According to the high-temperature sintering conditions of this embodiment, especially the preferred sintering conditions, excellent sintering and carbonization effects can be achieved on the coating layer precursor on the surface of the hydrogen storage alloy powder; and after sintering and carbonization treatment, the carbon elements loaded on the surface of the hydrogen storage alloy powder can accelerate the transfer of hydrogen molecules, and the material can still maintain good hydrogen storage kinetics after the carbon elements are loaded onto the hydrogen storage alloy powder.

[0038] In this disclosure, the apparatus for calcining carbon can be a muffle furnace or a tube furnace, both of which are conventional apparatuses in the art.

[0039] In one specific embodiment, the static crystallization process is a conventional static operation that can be carried out at room temperature, and the static time can be adjusted according to product requirements.

[0040] In one specific embodiment, the method further includes: performing solid-liquid separation treatment on the first product (e.g., centrifugation), drying the resulting solid product, and then performing the calcination carbonization treatment. Optionally, the centrifugation conditions include: a centrifugation speed of 5000~9500 rpm (including but not limited to 5000 rpm, 7500 rpm, 9000 rpm or any two values), and a centrifugation time of 4~15 min (including but not limited to 4 min, 5 min, 8 min, 10 min, 15 min or any two values). The drying conditions include: a vacuum drying temperature of 40~80℃ (including but not limited to 40℃, 60℃, 80℃ or any two of these values), and a vacuum drying time of 5~12h (including but not limited to 5h, 8h, 12h or any two of these values); preferably, the vacuum drying temperature is 60~75℃ and the vacuum drying time is 6~10h.

[0041] The second aspect of this disclosure provides a hydrogen storage alloy composite material prepared according to the method described in the first aspect of this disclosure.

[0042] In a preferred embodiment, the hydrogen storage alloy composite material includes a hydrogen storage alloy core and a carbon coating layer; the carbon coating layer includes carbon and elemental metals. In the hydrogen storage alloy composite material provided by this disclosure, the surface of the carbon-loaded hydrogen storage material forms a carbon coating layer, which can block oxygen from contacting the alloy surface. Furthermore, while resisting air oxidation, the carbon coating layer can also slow down the rate at which hydrogen permeates the surface of the composite material. In addition, the loaded carbon elements in this hydrogen storage alloy composite material do not affect hydrogen permeation within a certain range, while simultaneously promoting hydrogen diffusion within the alloy. This mitigates microcracks and alloy pulverization caused by volume shrinkage during hydrogen absorption and expansion during hydrogen absorption during the hydrogen absorption-desorption cycle, reduces grain boundary migration and grain growth caused by the hydrogen absorption-desorption heat effect, thereby improving the hydrogen desorption performance of the material.

[0043] In one embodiment, based on the total weight of the hydrogen storage alloy composite material, the content of the hydrogen storage alloy core can be 80-98% by weight, including but not limited to 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, or any two of these values. The content of the carbon coating layer can be 2-20% by weight, including but not limited to 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, or any two of these values. Preferably, based on the total weight of the hydrogen storage alloy composite material, the content of the hydrogen storage alloy core can be 90-98% by weight, and the content of the carbon coating layer can be 2-10% by weight. When the content of each component in the hydrogen storage alloy composite material is within the range of this embodiment, especially within the preferred range, the hydrogen storage alloy composite material exhibits better resistance to air poisoning and better hydrogen storage performance.

[0044] In one embodiment, the carbon coating layer comprises carbon and a metallic element; preferably, based on the total weight of carbon and metallic elements in the carbon coating layer, the carbon content can be 75-99% by weight, including but not limited to 75%, 80%, 85%, 90%, 95%, 98%, or any two of these values, and the metallic element content can be 1-25% by weight, including but not limited to 1%, 5%, 10%, 15%, 20%, 25%, or any two of these values; preferably, based on the total weight of carbon and metallic elements in the carbon coating layer, the carbon content is 90-99% by weight, and the metallic element content is 1-10% by weight. When the content of each component in the carbon coating layer of the hydrogen storage alloy composite material is within the range of this embodiment, especially within the preferred range, the hydrogen storage alloy composite material exhibits better resistance to air poisoning.

[0045] In a preferred embodiment, the weight ratio of the carbon coating layer to the hydrogen storage alloy core in the hydrogen storage alloy composite material can be 1:3 to 99, preferably 1:3 to 20. Optionally, in the carbon coating layer, the weight ratio of carbon to elemental metal is 1~20:1, preferably 3~9:1. When the content of each component in the hydrogen storage composite material is within the range of this embodiment, the hydrogen storage composite material has even better resistance to air poisoning.

[0046] In a preferred embodiment, the hydrogen storage alloy core further includes carbon; preferably, the weight ratio of the carbon coating layer to the carbon in the hydrogen storage alloy core is 1:1 to 10, more preferably 1:3 to 4. The bulk phase of the hydrogen storage alloy composite material provided in this disclosure may also contain carbon, which can have the effect of isolating poisonous gases; however, the carbon content in the bulk phase is extremely small and can be ignored.

[0047] In one specific embodiment, the particle size of the hydrogen storage alloy composite material can be 0.05~200μm, including but not limited to 0.05μm, 0.1μm, 0.5μm, 1μm, 2μm, 4μm, 6μm, 8μm, 10μm, 20μm, 40μm, 60μm, 80μm, 100μm, 120μm, 140μm, 160μm, 180μm, 200μm, or any range between two values; preferably 0.2~10μm; the thickness of the carbon coating layer can be 1~1000nm, 1nm, 10nm, 200nm, 400nm, 600nm, 800nm, 1000nm, preferably 5~50nm. The hydrogen storage composite material with the carbon coating layer thickness of this embodiment can balance air poisoning resistance and hydrogen transport performance.

[0048] The present disclosure is further described in detail below through examples. All raw materials used in the examples are commercially available.

[0049] In the following examples and comparative examples, the particle size of the titanium-based hydrogen storage alloy powder is 0.2-10 μm.

[0050] The carbon coating content and alloy core content of the samples, as well as the carbon content and elemental metal content in the carbon coating, were obtained by electro-coupled plasma atomic emission spectrometry (Optima 5300DV). The particle size of the sample was obtained by testing with a particle size analyzer (Mastersizer 3000+ Ultra laser particle size analyzer); The thickness of the carbon coating layer of the sample was determined by transmission electron microscopy (HT7800); The XRD images of the samples were obtained by X-ray diffraction (TK-XRD-201-X); SEM images and mapping elemental analysis test images of the samples were obtained by scanning electron microscopy (Talos F200X G2TEM); The hydrogen storage kinetics performance of the samples was tested using a fully automated hydrogen storage material PCT tester (H-Sorb 2600H); the hydrogen storage test conditions included: hydrogen pressure of 5~8MPa and reaction temperature of 298K (25℃).

[0051] Example 1 (1) Take titanium-based hydrogen storage alloy powder and add a methanol solution (organic solvent) of zinc acetate (first metal source, zinc salt) and dimethylimidazole (first organic ligand). The content of hydrogen storage alloy powder is 80% by weight, the content of first metal source is 10% by weight, and the content of first organic ligand is 10% by weight, based on the total weight of hydrogen storage alloy powder, first metal source and first organic ligand. Reaction ball milling promotes the in-situ synthesis of ZIF-8 material onto hydrogen storage alloy. The solid-liquid ratio is 1:20, the ball milling speed is 400 rpm, the ball-to-material ratio is 30:1, and the ball milling time is 10 h. The loading and unloading of the ball milling jar are carried out in a glove box to prevent air from entering and poisoning the hydrogen storage material during the preparation process. The first product is obtained. The content of ZIF-8 loaded on the surface of hydrogen storage alloy powder is 3% by weight (the Zn element content is obtained by ICP test, and then the ZIF-8 content is calculated).

[0052] (2) The slurry after ball milling and refining is separated into solid and liquid by centrifugation at a speed of 9000 rpm for 10 min. The solid sample after centrifugation is further dried in a vacuum oven at a temperature of 65℃ for 6 h.

[0053] (3) The first product after drying was calcined at high temperature in a tube furnace. The calcination atmosphere was argon, the calcination temperature was 900℃, and the calcination time was 6h to prepare a hydrogen storage alloy composite material, denoted as C1.

[0054] Figure 1 The image shows the XRD pattern of the titanium-based hydrogen storage alloy composite material C1 prepared in this embodiment after being exposed to air for 0 hours. The image shows that the composite material C1 has the characteristic peaks of titanium-based hydrogen storage alloys and the characteristic peaks of surface-loaded carbon elements.

[0055] Figure 2 The image shows the XRD pattern of the titanium-based hydrogen storage alloy composite material C1 prepared in this embodiment after 168 hours of exposure to air. The image shows that after 168 hours of poisoning in air, no obvious characteristic peaks of metal oxides appeared in the XRD curve of the composite material, indicating that the composite material was not poisoned by air.

[0056] Figure 3 The image shows a SEM mapping of the titanium-based hydrogen storage alloy composite material C1 prepared in this embodiment after 0 hours of exposure to air. The mapping image shows that carbon is uniformly distributed on the surface of the composite material, indicating that the preparation method of this embodiment can make carbon uniformly dispersed on the surface of the hydrogen storage alloy.

[0057] Figure 8This is a SEM mapping image of the titanium-based hydrogen storage alloy composite material C1 prepared in this embodiment after being exposed to air for 168 hours. According to the elemental distribution, the oxygen content on the surface of the composite material is extremely low, indicating that the carbon layer present on the surface of the hydrogen storage alloy prevents the air from poisoning the internal hydrogen storage alloy, which also indirectly proves... Figure 2 The result of the XRD image.

[0058] Figure 14 The hydrogen storage kinetic curve of the titanium-based hydrogen storage alloy composite material C1 prepared in this embodiment after exposure to air for 168 hours is shown in the image. According to the image, the hydrogen storage capacity of composite material C1 reaches 1.61 wt% in 30 minutes and reaches the maximum hydrogen storage capacity of 1.78 wt% within 60 minutes.

[0059] Figure 15 The image shows a line scan of the titanium-based hydrogen storage alloy composite material C1 prepared in this embodiment. The image shows that the carbon element is distributed in the same way on the surface and in the bulk of the alloy material. Since the carbon element is synthesized and grown in the titanium-based alloy material in situ, there is carbon element on the surface of the material.

[0060] Example 2 This embodiment refers to the preparation method in Example 1, except that zinc acetate is replaced with zinc chloride. The rest of the process is the same as in Example 1, and a hydrogen storage alloy composite material is prepared, which is denoted as C2.

[0061] Figure 1 The image shows the XRD pattern of the titanium-based hydrogen storage alloy composite material C2 prepared in this embodiment after 0 hours of exposure to air. The image shows that the composite material C2 has the characteristic peaks of titanium-based hydrogen storage alloy and the characteristic peaks of surface-loaded carbon elements.

[0062] Figure 2 The image shows the XRD pattern of the titanium-based hydrogen storage alloy composite material C2 prepared in this embodiment after 168 hours of exposure to air. Compared to Example 1, the XRD pattern shows peaks of metal oxides, indicating that the hydrogen storage alloy composite material C1 prepared using zinc acetate in Example 1 has better oxidation resistance.

[0063] Figure 4 This is a SEM mapping elemental analysis image of the titanium-based hydrogen storage alloy composite material C2 prepared in this embodiment after 0 hours of air exposure, compared with... Figure 3 Comparison, Figure 3 In Example 1, the carbon element distribution of composite material C1 is more uniform. The acetate ions used in Example 1 are easier to remove than the chloride ions in this example, and the combination between dimethylimidazole and zinc acetate is more complete. Therefore, the carbon element distribution on the material surface is more uniform.

[0064] Figure 9 This is a SEM mapping image of the titanium-based hydrogen storage alloy composite material C2 prepared in this embodiment after 168 hours of exposure to air. The image shows the presence of a certain amount of oxygen on the surface of the composite material, indirectly proving that... Figure 2 The XRD test results indicate the presence of metal oxides inside the material.

[0065] Figure 14 The hydrogen storage kinetics curve of the titanium-based hydrogen storage alloy composite material C2 prepared in this embodiment after 168 hours of air exposure is shown. The material reaches a hydrogen storage capacity of 1.17 wt% within 30 minutes and reaches a maximum hydrogen storage capacity of 1.24 wt% within 60 minutes. Compared with this embodiment, the composite material C1 provided in Example 1 has better hydrogen storage kinetics and superior hydrogen storage performance.

[0066] Example 3 This embodiment refers to the preparation method in Example 1, except that the ball milling time is 6 hours, and the rest of the process is the same as in Example 1. The hydrogen storage alloy composite material is prepared and is denoted as C3.

[0067] Figure 1 The image shows the XRD pattern of the titanium-based hydrogen storage alloy composite material C3 prepared in this embodiment after 0 hours of exposure to air. The image shows that the composite material C3 has the characteristic peaks of titanium-based hydrogen storage alloy and the characteristic peaks of surface-loaded carbon elements. In addition, because the ball milling time is too short, the carbon elements on the material surface are not obvious, which also illustrates the influence of ball milling time on the loading effect of carbon coating layer.

[0068] Figure 2 The image shows the XRD pattern of the titanium-based hydrogen storage alloy composite material C3 prepared in this embodiment after 168 hours of air exposure. Compared to Example 1, the XRD shows peaks of metal oxides, indicating that the material prepared in this embodiment is oxidized. In the air poisoning resistance test, part of the hydrogen storage alloy was poisoned, indicating that the composite material C1 prepared in Example 1 has better air poisoning resistance.

[0069] Figure 5 This is a SEM mapping elemental analysis image of the titanium-based hydrogen storage alloy composite material C3 prepared in this embodiment after 0 hours of air exposure, compared to... Figure 3 , Figure 3 The carbon element distribution of the composite material C1 shown is more uniform. In Example 1, the ball milling treatment was carried out according to the ball milling time optimized in this disclosure, and the ZIF-8 was more uniformly distributed on the surface of the hydrogen storage alloy, so that the carbon element was uniformly distributed on the surface of the hydrogen storage alloy after high-temperature calcination.

[0070] Figure 10This is a SEM mapping image of the titanium-based hydrogen storage alloy composite material C3 prepared in this embodiment after 168 hours of exposure to air. The presence of oxygen on the material surface at this time indirectly proves... Figure 2 The XRD data indicate that a certain amount of metal oxides are present inside the material.

[0071] Figure 14 The hydrogen storage kinetics curve of the titanium-based hydrogen storage alloy composite material C3 prepared in this embodiment after 168 hours of air exposure is shown. The material reaches a hydrogen storage capacity of 1.22% by weight within 30 minutes and reaches a maximum hydrogen storage capacity of 1.30% by weight within 60 minutes. Compared with Example 1, the reaction rate is slightly increased, but the carbon layer on the surface of composite material C1 in Example 1 is more uniform, and the maximum hydrogen storage capacity is higher.

[0072] Example 4 This embodiment refers to the preparation method in Example 1, except that the calcination temperature in the tubular calcination furnace is 600℃, and the rest of the process is the same as in Example 1, to prepare a hydrogen storage alloy composite material, denoted as C4.

[0073] Figure 1 The image shows the XRD pattern of the titanium-based hydrogen storage alloy composite material C4 prepared in this embodiment after 0 hours of exposure to air. The image shows that the titanium-based hydrogen storage alloy composite material C4 has the characteristic peaks of titanium-based hydrogen storage alloys and the characteristic peaks of surface-loaded carbon elements.

[0074] Figure 2 The image shows the XRD pattern of the titanium-based hydrogen storage alloy composite material C4 prepared in this embodiment after 168 hours of exposure to air. The characteristic peaks of carbon elements inside the material decrease, while the characteristic peaks of metal oxides increase. Due to the unevenness of the carbon layer, the material has poor oxidation resistance and is oxidized by air.

[0075] Figure 6 This is a SEM mapping elemental analysis image of the titanium-based hydrogen storage alloy composite material C4 prepared in this embodiment after 0 hours of air exposure, compared to... Figure 3 , Figure 3 The carbon element distribution in the C1 composite material is more uniform.

[0076] Figure 11 The image shown is a SEM mapping elemental analysis test image of the titanium-based hydrogen storage alloy composite material C4 prepared in this embodiment after 168 hours of exposure to air. Due to the uneven distribution of the carbon layer, the hydrogen storage alloy is poisoned, which is the same as the result shown in the XRD image.

[0077] Figure 14The hydrogen storage kinetics curve of the titanium-based hydrogen storage alloy composite material C4 prepared in this embodiment after 168 hours of air exposure is shown. The material reaches a hydrogen storage capacity of 1.53 wt% within 30 minutes and reaches a maximum hydrogen storage capacity of 1.62 wt% within 60 minutes. Compared with Example 1, the hydrogen storage kinetics of the material are significantly improved (the reaction rate is faster). However, the maximum hydrogen storage capacity of composite material C1 in Example 1 is higher than that of the composite material in this embodiment. This is because the surface carbon layer of C1 in Example 1 is more uniform, and the hydrogen storage alloy is less susceptible to poisoning.

[0078] Example 5 This embodiment refers to the preparation method in Example 1, except that the calcination time in the tubular calcination furnace is 0.5 h, and the rest of the process is the same as in Example 1, to prepare a hydrogen storage alloy composite material, denoted as C5.

[0079] Figure 1 The image shows the XRD pattern of the titanium-based hydrogen storage alloy composite material C5 prepared in this embodiment after 0 hours of exposure to air. The image shows that the composite material C5 has the characteristic peaks of titanium-based hydrogen storage alloys and the characteristic peaks of surface-loaded carbon elements.

[0080] Figure 2 The image shows the XRD pattern of the titanium-based hydrogen storage alloy composite material C5 prepared in this embodiment after 168 hours of exposure to air. Compared with Example 4, the characteristic peaks of carbon in the composite material C4 obtained in Example 4 are more obvious, indicating that the calcination temperature has a greater impact on carbon formation in Example 4, while the calcination time has a smaller impact in this embodiment.

[0081] Figure 7 The image shows a SEM mapping of the titanium-based hydrogen storage alloy composite material C5 prepared in this embodiment after 0 hours of air exposure. A small amount of carbon appears on the material surface. Due to incomplete carbon deposition, the carbon distribution on the surface is uneven.

[0082] Figure 12 The image shows the SEM mapping elemental analysis test image of the titanium-based hydrogen storage alloy composite material C5 prepared in this embodiment after 168 hours of exposure to air. The material was poisoned in the air poisoning test, and a certain amount of oxygen appeared on the surface. However, because a certain amount of carbon is still present, it plays a protective role against the poisoning of the hydrogen storage alloy. This proves that the more uniform the carbon distribution on the surface of the material, the stronger the material's resistance to poisoning.

[0083] Figure 14The hydrogen storage kinetics curve of the titanium-based hydrogen storage alloy composite material C5 prepared in this embodiment after 168 hours of air exposure shows that the material reaches a hydrogen storage capacity of 1.35 wt% within 30 minutes and reaches its maximum hydrogen storage capacity of 1.47 wt% within 60 minutes. This indirectly proves that the more carbon elements loaded on the material surface, the stronger the resistance to poisoning, and the more significant the decrease in the material's kinetic properties.

[0084] Example 6 This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that: The first metal source, zinc acetate, was replaced with cobalt salt (cobalt acetate), so that ZIF-67 was grown in situ on the surface of the hydrogen storage alloy powder during ball milling with dimethylimidazole (the first organic ligand); the rest of the process was the same as in Example 1, and the hydrogen storage alloy composite material was prepared, denoted as C6.

[0085] Figure 16 The images show SEM images and mapping elemental distribution diagrams of the titanium-based hydrogen storage alloy composite material C6 prepared in this embodiment. Compared with Example 1, ZIF-8 in Example 1 has a better loading effect on the surface of the titanium-based hydrogen storage alloy, and the carbon element distribution on the surface of the material is more uniform.

[0086] Figure 20 The image shown is the XRD pattern of the composite material obtained in this embodiment after 0 hours of air exposure. Because the carbon content on the material surface is low, no characteristic peak of carbon appears near 30°. Figure 21 The XRD image of the composite material in this embodiment after 168 hours of air exposure shows two distinct characteristic peaks of metal oxides on the material surface. Combined with the mapping image, it is confirmed that a portion of the sample in this embodiment was oxidized during the 168-hour air poisoning resistance test.

[0087] Figure 22 For this embodiment, SEM images and mapping elemental distribution maps of the sample after 168 hours of air poisoning are compared with those of Example 1. The carbon element protective film in the composite material obtained in Example 1 is intact, resulting in better resistance to air poisoning. Furthermore, the mapping image of C6 in the composite material is combined with... Figure 21 It can be seen that there is a certain amount of oxygen in the hydrogen storage alloy composite material, proving that the alloy material has been poisoned by air.

[0088] Example 7 This embodiment refers to the preparation method in Example 6, except that the high-temperature calcination atmosphere is air; the rest of the process is the same as in Example 6, and a hydrogen storage alloy composite material is prepared, which is denoted as C7.

[0089] Figure 17The images show the SEM image and mapping elemental distribution of the titanium-based hydrogen storage alloy composite material C7 prepared in this embodiment. It can be seen that the composite material C7 obtained in this embodiment was calcined at high temperature in air, so the surface metal elements were oxidized by the air, and a certain amount of oxygen elements were present on the material surface.

[0090] Figure 23 The images show SEM images and mapping elemental distribution diagrams of the composite material obtained in this embodiment after 168 hours of air poisoning. The carbon content on the C7 surface of the composite material is very uniformly distributed, while the oxygen content shows only a slight increase, indirectly demonstrating that the formation of a certain amount of carbon on the material surface can slow down the degree of air poisoning. However, it is necessary to ensure that no air is introduced during the material preparation process; otherwise, a large amount of alloy elements will be oxidized during the preparation process.

[0091] Figure 20 This is the XRD image of the composite material obtained in this embodiment after 0 hours of exposure to air. Because it was calcined at high temperature in air, many metal oxide impurity peaks are present in the material. Figure 17 The mapping images combined with the data show that some alloy elements were oxidized during the preparation process, but obvious carbon element characteristic peaks appeared near 30°, proving that a carbon layer can be generated on the alloy surface during the high-temperature process, and ZIF-67 characteristic peaks exist near 10°. That is, a certain amount of ZIF-67 still exists after calcination in this embodiment. Compared with Example 6, the carbonization treatment in Example 6 without calcination in air has a better effect and can better convert ZIF into carbon film.

[0092] Figure 21 The image shows the XRD pattern of the composite material obtained in this embodiment after 168 hours of exposure to air. The characteristic peaks of carbon are covered by the impurity peaks of metal oxides, which indirectly proves that the material is partially poisoned by air.

[0093] Example 8 This embodiment refers to the preparation method in Example 1, except that the amount of raw materials added is changed. Based on the total weight of the hydrogen storage alloy powder, the first metal source, and the first organic ligand, the content of the hydrogen storage alloy powder is 90% by weight, the content of the first metal source is 5% by weight, and the content of the first organic ligand is 5% by weight. The content of ZIF-8 loaded on the surface of the hydrogen storage alloy powder in the product obtained by ball milling is 1% by weight. The rest of the process is the same as in Example 1, and a hydrogen storage alloy composite material, denoted as C8, is prepared.

[0094] Figure 18 The images show the SEM and mapping images of the titanium-based hydrogen storage alloy composite material C8 prepared in this embodiment. Due to the low ZIF content, the mapping images show that carbon elements cannot be fully dispersed and loaded onto the surface of the titanium-based hydrogen storage alloy.

[0095] Figure 21 The image shows the XRD pattern of the composite material in this embodiment after 168 hours of air exposure. A partial carbon layer remains on the sample surface, thus providing some resistance to air poisoning. The characteristic peaks of the metal oxides near 30° are higher than those in Example 1, but... Figure 21 Compared with other embodiments and comparative examples, the carbon content is smaller, which indirectly shows that surface-loaded carbon can play a role in the material's resistance to air poisoning.

[0096] Example 9 This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that: Based on the total weight of the hydrogen storage alloy powder, the first metal source, and the first organic ligand, the content of the hydrogen storage alloy powder is 50% by weight, the content of the first metal source is 25% by weight, and the content of the first organic ligand is 25% by weight; the remaining processes are the same as in Example 1, and a hydrogen storage alloy composite material, denoted as C9, is prepared.

[0097] Example 10 This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that: Based on the total weight of the hydrogen storage alloy powder, the first metal source, and the first organic ligand, the content of the hydrogen storage alloy powder is 70% by weight, the content of the first metal source is 15% by weight, and the content of the first organic ligand is 15% by weight; the remaining processes are the same as in Example 1, and a hydrogen storage alloy composite material, denoted as C10, is prepared.

[0098] Example 11 This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that: MOF material (ZIF-8) was prepared using zinc acetate, dimethylimidazole, and methanol. The specific preparation method included: dissolving zinc acetate in methanol at a concentration of 10% by weight, and dissolving dimethylimidazole in methanol at a concentration of 10% by weight; mixing the two solutions with a molar ratio of zinc acetate to dimethylimidazole of 1:1; placing the mixture in a hydrothermal reactor and reacting at 120°C for 168 hours; replacing the solvent every 24 hours; and separating the solid and liquid components by centrifugation. The resulting sample was then dried in a vacuum oven to obtain a white crystalline powder, which was the ZIF-8 material. The obtained MOF material (ZIF-8) contained a second metal element (zinc) and a second organic ligand (dimethylimidazole). Based on the total weight of the MOF material, the content of the second metal element was 28.73% by weight, and the content of the second organic ligand was 71.27% by weight. Using existing MOF material (ZIF-8), the MOF material and hydrogen storage alloy powder were combined by ball milling (the ball milling conditions were the same as in Example 1), so that the MOF material coated the surface of the hydrogen storage alloy powder, and the first product was obtained; wherein the content of hydrogen storage alloy powder was 80% by weight, based on the total weight of hydrogen storage alloy powder and existing MOF material; the rest of the process was the same as in Example 1, and a hydrogen storage alloy composite material was prepared, denoted as C11.

[0099] Example 12 This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that: instead of calcining and carbonization, the product after the ball milling step is allowed to settle and then dried under vacuum after centrifugation at room temperature to obtain the hydrogen storage alloy composite material, denoted as C12.

[0100] Figure 19 The images show SEM images and mapping elemental distribution diagrams of the material obtained in this embodiment after exposure to air for 0 hours. Unlike Example 1, the material was not calcined at high temperature in an inert gas. According to the mapping images, the carbon element in the composite material obtained by high-temperature calcination of carbon in Example 1 is significantly more uniformly distributed on the surface of the titanium-based hydrogen storage alloy.

[0101] Figure 24 The images show SEM images and mapping elemental distribution diagrams of the material obtained in this embodiment after 168 hours of exposure to air. Since a dense carbon layer has not been formed on the surface of the titanium-based hydrogen storage alloy, ZIF-8 has a weaker resistance to air poisoning, and there is a certain amount of oxygen in the material. In contrast, the composite material obtained by high-temperature sintering carbon in Example 1 has a stronger resistance to air poisoning.

[0102] Figure 20 The image shown is the XRD pattern of the sample obtained in this embodiment after 0 hours of air exposure. Since there was no high-temperature calcination, the ZIF-8 characteristic peak is near 10°, indicating the presence of ZIF-8 in the system. However, in Example 1, the composite material obtained by high-temperature calcination of carbon transforms ZIF-8 into a superior carbon coating layer.

[0103] Figure 21 The image shown is the XRD pattern of the sample obtained in this embodiment after 168 hours of air exposure. The alloy elements in the system are oxidized to metal oxides, and... Figure 24 The mapping images show that the unbaked ZIF-8 loaded on the surface of the titanium-based hydrogen storage alloy cannot provide good resistance to air poisoning. Compared with Example 1, the composite material obtained by high-temperature calcination in Example 1 has better resistance to air poisoning.

[0104] Figure 25The hydrogen storage kinetics curve of the material prepared in this embodiment is shown. The material reaches a hydrogen storage capacity of 1.69 wt% within 30 min, and the titanium-based hydrogen storage alloy reaches the maximum hydrogen storage capacity of 1.78 wt% within 60 min. Figure 26 The hydrogen storage kinetics curve of the material obtained in this embodiment after 168 hours of air poisoning is shown. The hydrogen storage capacity of the material reaches 1.45 wt% within 30 minutes, and the titanium-based hydrogen storage alloy reaches its maximum hydrogen storage capacity of 1.50 wt% within 60 minutes. The change in hydrogen storage capacity demonstrates that some alloy elements are oxidized to metal oxides, losing their hydrogen storage capacity and causing a decrease in the maximum hydrogen storage capacity. Compared to Comparative Example 1, which had 0 hours of air poisoning, the hydrogen storage capacity of the material was similar in the first 30 minutes, indicating that the surface loading of ZIF-8 does not affect the hydrogen storage rate. Compared to Example 1, the composite material obtained in Example 1 has a higher maximum hydrogen storage capacity and better resistance to air poisoning after 168 hours of air poisoning.

[0105] Comparative Example 1 This comparative example follows the preparation method in Example 1, except that zinc acetate (the first metal source, zinc salt) and dimethylimidazole (the first organic ligand) are not added during the ball milling process. The rest of the process is the same as in Example 1, and a hydrogen storage alloy material, denoted as D1, is prepared.

[0106] according to Figure 2 As shown, the material is severely poisoned by air, with a large number of metal oxide impurity peaks, indicating that the material is severely oxidized by air.

[0107] according to Figure 13 The presence of a large amount of oxygen on the surface of the material indicates that it has been oxidized by air and has been severely oxidized into metal oxides.

[0108] Figure 25 The hydrogen storage kinetics curves of the materials prepared in this comparative example are shown. The material reaches a hydrogen storage capacity of 1.70 wt% within 30 min, while the titanium-based hydrogen storage alloy reaches its maximum hydrogen storage capacity of 1.78 wt% within 60 min. Figure 14 and Figure 26 The results showed that after 168 hours of exposure to air, the material's hydrogen storage capacity reached 0.94 wt% within 30 minutes and reached its maximum capacity of 1.01 wt% within 60 minutes. This change in hydrogen storage capacity demonstrates that during the 168-hour air poisoning test, a portion of the elemental metal was oxidized to metal oxides, losing its hydrogen storage capacity and thus causing a decrease in the material's maximum hydrogen storage capacity.

[0109] The component content, particle size, and other data of the hydrogen storage alloy composite materials obtained in the above examples and comparative examples are listed in Table 1 below.

[0110] Table 1

[0111] The hydrogen storage performance data (after 168 hours of exposure to air) of the hydrogen storage alloy composite materials obtained in the above examples and comparative examples are listed in Table 2 below.

[0112] Table 2

[0113] According to the data in Table 2 above: Compared to the hydrogen storage alloy material obtained in Comparative Example 1 (which only contains the hydrogen storage alloy and does not contain the carbon coating layer), the hydrogen storage alloy composite materials prepared in Examples 1-12 according to the method provided in this disclosure have improved hydrogen storage capacity at 30 min and 60 min after exposure to air for 168 h, indicating that the hydrogen storage alloy composite materials prepared by the method provided in this disclosure have high resistance to air poisoning. Comparing Example 1 with Example 3, the ball milling time in Example 1 is within the preferred range provided in this disclosure. The hydrogen storage alloy composite material obtained in Example 1 has higher 30-minute and 60-minute mass hydrogen storage capacity after 168 hours of exposure to air, and better resistance to air poisoning. Comparing Example 1 with Examples 4-5, the calcination conditions in Example 1 are within the preferred range provided in this disclosure. The hydrogen storage alloy composite material obtained in Example 1 has higher 30-minute and 60-minute mass hydrogen storage capacity after 168 hours of exposure to air, and better resistance to air poisoning. Comparing Example 1 with Example 6, ZIF-8 was grown in situ on the surface of hydrogen storage alloy powder in Example 1. Compared with the hydrogen storage alloy composite material obtained by in situ growth of ZIF-67 in Example 7, the hydrogen storage alloy composite material obtained in Example 1 had higher 30-minute and 60-minute mass hydrogen storage capacity after 168 hours of exposure to air, and better resistance to air poisoning. Comparing Example 9 with Example 10, the raw material ratio in the coating material used in Example 10 is within the optimized range provided in this disclosure, and the hydrogen storage alloy composite material obtained in Example 10 has better air poisoning resistance and hydrogen storage capacity; further comparing Examples 1 and 8 with Example 10, the composition content of the raw materials in Examples 1 and 8 is within the further preferred range provided in this disclosure, and the hydrogen storage alloy composite materials obtained in Examples 1 and 8 have higher 30-minute and 60-minute mass hydrogen storage capacity after 168 hours of exposure to air, and better air poisoning resistance; Comparing Example 1 with Example 11, it can be seen that the ZIF-8 carbon coating precursor was generated in situ by ball milling in Example 1. Compared with the ball milling coating using MOF material in Example 1, the hydrogen storage alloy composite material prepared in Example 1 has better hydrogen storage performance and air poisoning resistance. Comparing Example 1 with Example 12, Example 12 involved ball milling followed by static crystallization without sintering and carbonization. The hydrogen storage alloy composite material prepared in Example 1 according to the sintering and carbonization method of this disclosure exhibited higher hydrogen storage capacity at 30 minutes and 60 minutes after exposure to air for 168 hours than that in Example 12, indicating that the hydrogen storage alloy composite material in Example 1 has better resistance to air poisoning.

[0114] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0115] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0116] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method of preparing a hydrogen storage alloy composite material, characterized by, Includes the following steps: S1. Contact the hydrogen storage alloy powder, organic solvent and coating material, and perform ball milling to obtain a first product; wherein the coating material includes a first metal source and a first organic ligand, or the coating material includes MOF material; S2. Optionally, the first product is subjected to calcination and carbonization treatment.

2. The method of claim 1, wherein, When the coating material includes a first metal source and a first organic ligand: The first metal source is selected from one or more of zinc salts, cobalt salts, copper salts, and magnesium salts; optionally, the zinc salt is selected from one or more of zinc acetate, zinc chloride, and zinc nitrate; the cobalt salt is selected from one or more of cobalt acetate, cobalt chloride, and cobalt nitrate; the copper salt is selected from one or more of copper acetate, copper chloride, and copper nitrate; and the magnesium salt is selected from one or more of magnesium acetate, magnesium chloride, and magnesium nitrate. Optionally, the first organic ligand is selected from one or more of dimethylimidazole, azirethylcarbazole, dimethylpyridine, terephthalic acid, and toluene; Preferably, the first metal source is selected from one or more zinc salts, more preferably zinc acetate; the first organic ligand includes dimethylimidazole.

3. The method of claim 1, wherein, When the coating material includes MOF material: The MOF material contains a second metallic element and a second organic ligand; Preferably, the second metallic element is selected from one or more of cobalt, zinc, copper, and magnesium; The second organic ligand moiety is selected from one or more of dimethylimidazolium, azirethylcarbazole, dimethylpyridine, terephthalic acid, and toluene; More preferably, based on the total weight of the MOF material, the content of the second metal element is 2-45% by weight, and the content of the second organic ligand is 55-98% by weight; preferably, the content of the metal portion is 10-30% by weight, and the content of the second organic ligand is 70-90% by weight.

4. The method of claim 1, wherein, The hydrogen storage alloy powder is selected from one or more of titanium-based hydrogen storage alloys, rare earth-based hydrogen storage alloys, vanadium-based hydrogen storage alloys, and magnesium-based hydrogen storage alloys; preferably, it is a titanium-based hydrogen storage alloy. Optionally, the particle size of the hydrogen storage alloy powder is 0.05~200μm, preferably 0.2~10μm; Optionally, the organic solvent is selected from one or more of methanol, isopropanol, ethanol and diethyl ether, preferably methanol.

5. The method of claim 1, wherein, Based on the total weight of the hydrogen storage alloy powder, the first metal source, and the first organic ligand, the content of the hydrogen storage alloy powder is 60-98% by weight, the content of the first metal source is 1-20% by weight, and the content of the first organic ligand is 1-20% by weight; preferably, the content of the hydrogen storage alloy powder is 80-96% by weight, the content of the first metal source is 2-10% by weight, and the content of the first organic ligand is 2-10% by weight. Alternatively, based on the total weight of the hydrogen storage alloy powder and the MOF material, the content of the hydrogen storage alloy powder is 60-98% by weight, and the content of the MOF material is 2-40% by weight; preferably, the content of the hydrogen storage alloy is 80-96% by weight, and the content of the MOF material is 4-20% by weight.

6. The method of claim 1, wherein, In step S1, the conditions for ball milling include: a solid-liquid ratio of 1:2 to 50, preferably 1:5 to 25; a ball milling speed of 200 to 400 rpm, preferably 300 to 400 rpm; a ball milling time of 2 to 20 h, preferably 10 to 16 h; and a ball-to-material ratio of 10 to 50:1, preferably 25 to 35:

1.

7. The method of claim 1, wherein, In step S2, the conditions for the calcination carbonization treatment include: a calcination temperature of 400~1000℃ and a calcination time of 0.5~8h; preferably, a calcination temperature of 700~900℃ and a calcination time of 0.5~6h; and a calcination atmosphere selected from one or more of argon, nitrogen and air.

8. The method of claim 1, wherein, The method also includes: The first product is subjected to solid-liquid separation treatment, and the resulting solid product is dried; then the calcination and carbonization treatment is performed. Optionally, the solid-liquid separation process includes centrifugation. Preferably, the centrifugation conditions include: a centrifugation speed of 5000~9500 rpm and a centrifugation time of 4~15 min. The drying conditions include: a vacuum drying temperature of 40~80℃ and a vacuum drying time of 5~12h; preferably, the vacuum drying temperature is 60~75℃ and the vacuum drying time is 6~10h.

9. The hydrogen storage alloy composite material prepared by the method according to any one of claims 1 to 8.

10. The hydrogen storage alloy composite material according to claim 9, characterized by The hydrogen storage alloy composite material includes a hydrogen storage alloy core and a carbon coating layer; Preferably, based on the total weight of the hydrogen storage alloy composite material, the content of the hydrogen storage alloy core is 80-98% by weight, and the content of the carbon coating layer is 2-20% by weight. Preferably, based on the total weight of the hydrogen storage alloy composite material, the content of the hydrogen storage alloy core is 90-98% by weight, and the content of the carbon coating layer is 2-10% by weight. Optionally, the carbon coating layer comprises carbon and elemental metals; preferably, based on the total weight of carbon and elemental metals in the carbon coating layer, the carbon content is 75-99% by weight and the elemental metal content is 1-25% by weight; preferably, the carbon content is 90-99% by weight and the elemental metal content is 1-10% by weight.

11. The hydrogen storage alloy composite material according to claim 10, characterized by The particle size of the hydrogen storage alloy composite material is 0.05~200μm, preferably 0.2~10μm; The thickness of the carbon coating layer is 1~1000nm, preferably 5~50nm.

Images