Hydrogen storage material, method for producing the same, and hydrogen storage system

Abstract

The application belongs to the technical field of hydrogen storage materials, and particularly relates to a hydrogen storage material, a preparation method thereof and a hydrogen storage system. The hydrogen storage material is prepared from raw materials including the following components in percentage by mass: hydrogen storage alloy powder 90%-97.5%, volume expansion buffer 1%-5%, heat-conducting material 1%-5%, and additive 0.5%-3%. The additive includes at least one of silane coupling agent and polyimide. The raw material components are mixed and cold-pressed into a shape, and then heat-treated at a temperature of 110-150 DEG C for 4-12 hours in an inert atmosphere, to obtain the hydrogen storage material.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage materials technology, and particularly relates to a hydrogen storage material, its preparation method, and a hydrogen storage system. Background Technology

[0002] Solid-state hydrogen storage technology, particularly the approach using hydrogen storage alloys as the core medium, has shown great potential in on-board hydrogen storage and stationary energy storage due to its advantages such as high hydrogen storage density, mild operating conditions, and good intrinsic safety. However, this field has long faced a core technical bottleneck: the cycle stability of hydrogen storage alloy materials in practical applications, which directly affects the service life and safety of hydrogen storage systems.

[0003] During reversible hydrogen absorption and desorption cycles, the movement of hydrogen atoms into and out of the metal lattice of hydrogen storage alloys triggers drastic changes in cell parameters, leading to volume expansion and contraction of up to 20%-30% in the alloy particles. This repeated stress inevitably causes microcracks to appear inside the alloy particles, which continue to expand with each cycle, eventually resulting in severe pulverization of the material from macroscopic bulk or large particles into micron- or even nano-sized powders. This pulverization phenomenon brings a series of chain-reaction negative effects: First, the packing density of the powder is much lower than that of the bulk, resulting in a decrease in the system's hydrogen storage density; second, the fine powder can clog system pipelines and deteriorate the heat transfer performance of the bed, because the contact thermal resistance between powder particles is extremely high, preventing the heat of hydrogen absorption and desorption from being transferred or discharged in a timely manner, severely affecting kinetic performance; most seriously, this greatly shortens the cycle life of the material, posing a fundamental threat to the long-term stable operation of the hydrogen storage system. To solve this problem, existing technologies typically employ a method of combining hydrogen storage alloy powder with polymer binders, hoping to fix the alloy particles together through the "adhesive" effect of the binder. However, this simple physical mixing and composite strategy is not ideal. Its deeper defects are as follows: First, the bonding strength is insufficient. The simple physical coating force is difficult to resist the huge volume expansion stress of the hydrogen storage alloy. During cycling, the alloy particles and the binder are very prone to "debonding", leading to structural failure. Second, the interfacial compatibility is poor. The hydrogen storage alloy is an inorganic metal phase, while the binder is an organic polymer phase. The natural incompatibility between the two leads to weak bonding force. Third, it aggravates the thermal conductivity problem. Polymer binders are usually poor conductors of heat. Their introduction further exacerbates the deterioration of the overall thermal conductivity of the composite material.

[0004] Therefore, the key technical challenge in this field is how to construct a composite hydrogen storage system that can fundamentally solve the interfacial bonding problem while synergistically addressing the contradiction between mechanical buffering and efficient thermal conductivity. Specifically, existing technologies urgently need a new technical solution aimed at providing a bulk solid-state hydrogen storage material that not only effectively inhibits pulverization but also ensures a strong and stable interfacial bond between the hydrogen storage alloy particles and the buffering matrix during long-term cycling, thereby achieving true structural integration and a long cycle life. Simultaneously, this solution must also consider the overall thermal conductivity of the material to guarantee rapid hydrogen absorption and desorption kinetics. How to optimize the inorganic-organic interface at the atomic or molecular scale through specific component selection and innovative preparation processes, and construct a three-dimensional network that combines structural toughness and thermal conductivity, is a key technical challenge that those skilled in the art urgently need to overcome, but for which no ideal solution has yet been found. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a hydrogen storage material, its preparation method, and a hydrogen storage system.

[0006] Firstly, a hydrogen storage material employs the following technical solution:

[0007] A hydrogen storage material, wherein the raw materials of the hydrogen storage material, by mass percentage, comprise the following components: 90%-97.5% hydrogen storage alloy powder, 1%-5% volume expansion buffer, 1%-5% thermally conductive material, and 0.5%-3% additives; wherein the additives include at least one of silane coupling agents and polyimide.

[0008] The above-mentioned raw material components are mixed and cold-pressed, and then heat-treated at 110℃~150℃ for 4h~12h in an inert atmosphere. After cooling, the hydrogen storage material is obtained.

[0009] Furthermore, the hydrogen storage alloy powder comprises AB2 type hydrogen storage alloy and V-based BCC type hydrogen storage alloy.

[0010] Furthermore, the mass ratio of the AB2 type hydrogen storage alloy to the V-based BCC type hydrogen storage alloy is 1:3-5.

[0011] Furthermore, the volume expansion buffer is one or more of low-density polyethylene, polyether ester elastomer, and polyvinyl fluoride; the thermally conductive material is one or more of expanded graphite, alumina, and hexagonal boron nitride; and the additive is one or more of silane coupling agent and polyimide.

[0012] Secondly, a method for preparing a hydrogen storage material, employing the following technical solution:

[0013] A method for preparing a hydrogen storage material includes the following steps:

[0014] Hydrogen storage alloy powder, volume expansion buffer, thermally conductive material and additives are mechanically mixed to obtain precursor powder; the precursor powder is cold-pressed to obtain pressed material; the pressed material is heat-treated in an inert atmosphere and then cooled to obtain the hydrogen storage material.

[0015] Furthermore, the particle size of the hydrogen storage alloy powder is less than 10 mesh, and the particle size of the volume expansion buffer and the thermally conductive material is less than 200 mesh.

[0016] Furthermore, the pressure for cold pressing is 3MPa-15MPa, and the holding time is 5min-30min.

[0017] Furthermore, the heat treatment temperature is 110℃-150℃, and the heating time is 4h-12h.

[0018] Furthermore, the inert atmosphere is nitrogen or argon.

[0019] Thirdly, a hydrogen storage system employs the following technical solution:

[0020] A hydrogen storage system comprising the aforementioned hydrogen storage material, the hydrogen storage system being used in a proton exchange membrane fuel cell system.

[0021] The beneficial effects of this invention are:

[0022] The hydrogen storage material provided by this invention involves cold-pressing the raw material components and then heat-treating them at a high temperature of 110℃-150℃. During the heat treatment process, on the one hand, the polymer material, which acts as a volume expansion buffer, softens and flows; on the other hand, the silane coupling agent, which acts as an additive, is efficiently activated, causing it to build a molecular bridge based on covalent bonds between the inorganic surface of the hydrogen storage alloy powder and the organic phase of the volume expansion buffer. This interfacial modification at the atomic scale fundamentally solves the incompatibility between the inorganic and organic phases. After cooling and solidification, a three-dimensional polymer network skeleton with strong interfacial bonding based on chemical bonding is formed inside the material. This skeleton structure can effectively disperse and absorb the huge volume expansion stress generated by the alloy particles during hydrogen absorption and desorption cycles, thereby inhibiting particle debonding and the generation of microcracks, and ensuring the long-term unobstructed thermal conductivity pathway formed by the thermally conductive material. Ultimately, this gives the hydrogen storage material excellent stability in maintaining macroscopic structural integrity, extremely low hydrogen storage capacity decay rate, and continuously efficient hydrogen absorption and desorption kinetics under long-term cycling. Attached Figure Description

[0023] Figure 1The figures show the hydrogen storage performance curves of the hydrogen storage alloy powder raw materials (AB2 type hydrogen storage alloy and V-based BCC type hydrogen storage alloy) used in this application, wherein: (a) is the PCT curve of the La-doped AB2 type hydrogen storage alloy at 5℃; (b) is the PCT curve of the V-doped AB2 type hydrogen storage alloy at 5℃. 75 Ti 11 Cr 12 The decrease in hydrogen storage capacity of Fe2 alloy with the number of cycles.

[0024] Figure 2 This is a schematic diagram of the preparation process of a hydrogen storage material provided in Embodiment 1 of the present invention.

[0025] Figure 3 The hydrogen storage performance curves of the hydrogen storage material provided in Example 1 are shown, where: (a) is the hydrogen absorption kinetic curve at different temperatures; and (b) is the hydrogen absorption cycle performance curve after 20 cycles.

[0026] Figure 4 The images shown are scanning electron microscope (SEM) images and macroscopic photographs of the hydrogen storage material provided in Example 1, wherein: (a, b) are SEM images before hydrogen absorption and desorption cycles; (c) are macroscopic photographs before hydrogen absorption and desorption cycles; (d, e) are SEM images after 20 cycles of hydrogen absorption and desorption; and (f) are macroscopic photographs after 20 cycles of hydrogen absorption and desorption.

[0027] Figure 5 The following are performance and morphology images of the hydrogen storage material provided in Example 2: (a) is a cross-sectional photograph of the hydrogen storage material of Example 2 after 20 cycles of hydrogen absorption and desorption; (b) is the hydrogen absorption cycle performance curve of the hydrogen storage material of Example 2 after 20 cycles.

[0028] Figure 6 The following are performance and morphology images of the hydrogen storage material provided for Comparative Example 1: (a) is a macroscopic photograph of the material of Comparative Example 1 after 20 cycles of hydrogen absorption and desorption, which shows severe pulverization; (b) is the hydrogen absorption cycle performance curve of the hydrogen storage material of Comparative Example 1 after 20 cycles.

[0029] Figure 7 Macroscopic photographs showing the structural deterioration and through-cracks of the hydrogen storage material provided for Comparative Example 3 after 20 cycles of hydrogen absorption and desorption. Detailed Implementation

[0030] The following detailed description, in conjunction with embodiments, provides an overview of the hydrogen storage material, its preparation method, and the hydrogen storage system described in this invention. For the sake of simplicity, this document cannot exhaustively list all alternative technical features and implementation schemes included in this invention. Therefore, those skilled in the art should understand that any technical feature and implementation scheme within these embodiments does not limit the scope of protection of this invention. The scope of protection includes all alternative technical features and implementation schemes adopted by those skilled in the art without inventive effort. Specifically, any implementation scheme obtained by replacing any technical feature in this invention or by combining any two or more technical features provided by this invention should be within the scope of protection of this invention. Where specific techniques and conditions are not specified in the embodiments, they are performed according to the techniques and conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0031] This embodiment provides a hydrogen storage material, which, by mass percentage, is composed of the following components:

[0032] Hydrogen storage alloy powder: 90%-97.5%;

[0033] Volume expansion buffer: 1%-5%;

[0034] Thermally conductive materials: 1%-5%;

[0035] Additives: 0.5%-3%;

[0036] Furthermore, the sum of the mass percentages of the above components is 100%.

[0037] In some embodiments, the hydrogen storage alloy powder comprises AB2 type hydrogen storage alloy and V-based BCC type hydrogen storage alloy.

[0038] In some embodiments, the mass ratio of AB2 type hydrogen storage alloy to V-based BCC type hydrogen storage alloy is 1:3-5.

[0039] In some embodiments, the volume expansion buffer is one or more of low-density polyethylene, polyether ester elastomer, and polyvinyl fluoride; the thermally conductive material is one or more of expanded graphite, alumina, and hexagonal boron nitride; and the additive is one or more of silane coupling agent and polyimide.

[0040] This embodiment provides a bulk solid hydrogen storage material. In one specific implementation, the hydrogen storage material is a composite material composed of multiple components. By mass percentage, its composition may be: 90% to 97.5% hydrogen storage alloy powder, 1% to 5% volume expansion buffer, 1% to 5% thermally conductive material, and 0.5% to 3% additives, ensuring that the total mass percentage of all components is 100%. This formulation design aims to achieve an ideal balance between hydrogen storage performance, structural stability, and thermal conductivity.

[0041] To achieve excellent overall hydrogen storage performance, the hydrogen storage alloy powder is preferably composed of at least two different types of alloys, specifically including AB2-type hydrogen storage alloys and V-based BCC-type hydrogen storage alloys. AB2-type hydrogen storage alloys (such as TiCrMn alloys) exhibit excellent low-temperature hydrogen desorption kinetics, while V-based BCC-type hydrogen storage alloys possess the advantage of high reversible hydrogen storage capacity. In a preferred embodiment, to synergize the advantages of these two alloys and meet the dual requirements of cold start and high capacity in fuel cells, the mass ratio of AB2-type hydrogen storage alloy to V-based BCC-type hydrogen storage alloy can be set to a range of 1:3 to 1:5.

[0042] To effectively suppress the pulverization of hydrogen storage alloys during cycling, the volume expansion buffer plays a crucial role. This buffer is preferably a polymeric material with good flexibility and chemical stability; for example, it can be any one of low-density polyethylene, polyether ester elastomer, or polyvinyl fluoride, or a combination of several of them. Similarly, to address the problem of poor thermal conductivity in the hydrogen storage material bed, the thermally conductive material is preferably an inorganic material with high intrinsic thermal conductivity; for example, it can be any one or a combination of expanded graphite, alumina, and hexagonal boron nitride. Furthermore, to enhance the bonding strength between the component particles and improve the overall mechanical properties of the material, additives can be added, which can be one or more of silane coupling agents or polyimides with excellent thermal stability.

[0043] This embodiment provides a method for preparing a hydrogen storage material, including the following steps:

[0044] Hydrogen storage alloy powder, volume expansion buffer, thermally conductive material and additives are mechanically mixed to obtain precursor powder; the precursor powder is cold-pressed to obtain pressed material; the pressed material is heat-treated in an inert atmosphere and then cooled to obtain hydrogen storage material.

[0045] In some embodiments, the particle size of the hydrogen storage alloy powder is less than 10 mesh, and the particle size of the volume expansion buffer and the thermally conductive material is less than 200 mesh.

[0046] In some embodiments, the cold pressing pressure is 3MPa-15MPa, and the holding time is 5min-30min.

[0047] In some embodiments, the heat treatment temperature is 110℃-150℃, and the heating time is 4h-12h.

[0048] In some embodiments, the inert atmosphere is nitrogen or argon.

[0049] This embodiment provides a method for preparing the above-mentioned hydrogen storage material. The method has a clear process flow, is easy to control, and can be applied industrially.

[0050] The first step in this preparation method is the preparation and mixing of materials. A predetermined amount of hydrogen storage alloy powder, volume expansion buffer powder, thermally conductive material powder, and additives are thoroughly mechanically mixed to obtain a uniform precursor powder. To ensure effective mixing and subsequent molding quality, the particle size of the raw materials can be controlled. In some embodiments, the particle size of the hydrogen storage alloy powder can be controlled to be less than 10 mesh, while the particle sizes of the volume expansion buffer and thermally conductive material can be controlled to be less than 200 mesh.

[0051] The second step is cold pressing. The uniformly mixed precursor powder is placed in a mold and pressed under pressure at room temperature to initially form a block-shaped pressed material with a specific shape and density. The pressure and time of cold pressing are important parameters affecting the final material density. In one specific embodiment, the cold pressing pressure can be set in the range of 3 MPa to 15 MPa, and the holding time can be 5 minutes to 30 minutes.

[0052] The third step is heat treatment. The cold-pressed block material is placed in a heating device (such as a tube furnace) filled with an inert atmosphere for heat treatment. The purpose of this step is to soften or react the volume expansion buffer and additives, thereby forming a strong bonded network between the particles, giving the material final mechanical strength and structural stability. To prevent oxidation of the hydrogen storage alloy at high temperatures, this process must be carried out in an inert atmosphere, such as nitrogen or argon. The temperature and time of the heat treatment need to be precisely controlled. In one feasible embodiment, the heating temperature can be controlled between 110°C and 150°C, and the heating time can be between 4 hours and 12 hours. After heat treatment, the material is allowed to cool naturally or controlled to room temperature to obtain the final bulk solid hydrogen storage material.

[0053] This embodiment provides a hydrogen storage system comprising the aforementioned hydrogen storage material, which is used in a proton exchange membrane fuel cell system.

[0054] This embodiment also provides a hydrogen storage system. A key feature of this system is that it internally contains or includes the bulk solid hydrogen storage material described in any of the foregoing embodiments as a hydrogen storage medium. Because this hydrogen storage material possesses advantages such as high hydrogen storage capacity, excellent cycle stability, good kinetic performance, and high safety, it can significantly improve the overall performance of the entire hydrogen storage system. In a specific application scenario, this hydrogen storage system can serve as a hydrogen source, integrated with a proton exchange membrane fuel cell system to provide a stable and reliable hydrogen supply, and is particularly suitable for applications with stringent requirements for low-temperature start-up performance and long cycle life of hydrogen storage devices.

[0055] Example

[0056] Example 1

[0057] This embodiment 1 provides a hydrogen storage material and its preparation method.

[0058] This embodiment 1 provides a hydrogen storage material, comprising 9.45g of a hydrogen storage alloy mixed powder, 0.2g of low-density polyethylene powder, 0.3g of expanded graphite powder, and 0.05g of silane coupling agent KH551; wherein, the hydrogen storage alloy powder is composed of AB2 type hydrogen storage alloy (La-doped Ti). 1.2 CrMn alloy) and V-based BCC type hydrogen storage alloy (V 75 Ti 11 Cr 12 The composition is Fe2 alloy, with a mass ratio of 1:3. AB2 type hydrogen storage alloy (La-doped Ti) 1.2 CrMn alloy) and V-based BCC type hydrogen storage alloy (V 75 Ti 11 Cr 12 The properties of Fe2 alloys are as follows: Figure 1 As shown, ( Figure 1 a) From Hanbing Zhang, Jichao Ye, Qingjun Chen, et al. Effect of La Doping on Kinetic and Thermodynamic Performances of Ti 1.2 CrMnAlloy upon De / Hydrogenation[J]. ACS Omega, 2022(7): 40807-40814. ( Figure 1b) From Qiuwei Huang, Hanyang Kong, Yigang Yan, et al. A cost-effective vanadium-based alloy with exceptional capacity and durability for hydrogen storage[J]. Journal of Power Sources, 2025(640): 236807. By Figure 1 It can be seen that the AB2 type hydrogen storage alloy has the characteristics of low hysteresis plateau and excellent low-temperature hydrogen desorption performance. Figure 1 a) and the high reversible hydrogen storage capacity of V-based BCC-type hydrogen storage alloys ( Figure 1 b) Achieving efficient coupling can meet the dual requirements of PEMFC fuel cell systems for low-temperature self-desorption hydrogen cold start of solid hydrogen storage devices and high reversible hydrogen storage capacity.

[0059] This embodiment 1 also provides a method such as Figure 2 The method for preparing the hydrogen storage material shown includes the following steps:

[0060] AB2 type hydrogen storage alloy (La-doped Ti) 1.2 CrMn alloy) and V-based BCC type hydrogen storage alloy (V 75 Ti 11 Cr 12 The Fe2 alloy was mixed in a mass ratio of 1:3, and then mechanically ground under inert gas protection and sieved to obtain a hydrogen storage alloy mixed powder with a particle size of less than 20 mesh.

[0061] Commercially available low-density polyethylene powder with a particle size of less than 300 mesh was prepared as a volume expansion buffer, commercially available expanded graphite powder with a particle size of less than 300 mesh was prepared as a thermal conductive material, and silane coupling agent KH551 was prepared as an additive.

[0062] All the above components are placed in a mixing device and thoroughly mechanically mixed until a uniform precursor powder is formed. The uniformly mixed precursor powder is loaded into a tableting mold, and a pressure of 5 MPa is applied on a cold press and held for 15 minutes to obtain a pre-pressed circular sheet-like block material.

[0063] The pressed bulk material was transferred to a tube furnace and heated to 120°C under a protective atmosphere of flowing argon (Ar) for 4 hours to promote the thermal curing of the polymer. After the heat treatment, heating was stopped and the material was allowed to cool naturally to room temperature in an argon atmosphere to obtain the hydrogen storage material of Example 1.

[0064] Performance testing

[0065] After the hydrogen storage material prepared in Example 1 was activated, its hydrogen storage performance and structural stability were tested.

[0066] (1) Hydrogen absorption kinetics performance test:

[0067] like Figure 3 As shown in Figure a, the hydrogen absorption kinetics curves of the bulk material at different temperatures were tested. Under the conditions of 348 K (75 °C) and 5 MPa hydrogen pressure, the material exhibits excellent hydrogen absorption kinetics, absorbing up to 90% of its saturated hydrogen storage capacity in just 88 seconds, demonstrating a rapid hydrogen absorption rate. This is attributed to the excellent thermal conductivity network constructed by the thermally conductive material.

[0068] (2) Cyclic stability test:

[0069] like Figure 3 As shown in b, the material underwent a 20-week hydrogen adsorption / desorption cycling test. In the first week of cycling, the material's hydrogen storage capacity was 1.473 wt%. After 5, 10, and 15 weeks of cycling, the capacity decreased slightly to 1.431 wt%, 1.416 wt%, and 1.409 wt%, respectively. After completing 20 cycles, the hydrogen storage capacity remained stable at 1.409 wt%, with a total capacity decay rate of only 5% compared to the initial capacity. This indicates that the bulk material prepared in this embodiment exhibits extremely excellent cycling stability.

[0070] (3) Microstructure and macromorphological analysis:

[0071] like Figure 4 As shown, the morphology of the material before and after cycling was compared using scanning electron microscopy (SEM) and photographs. Before cycling, the material surface was smooth and dense. Figure 4 a, b), the whole is in a complete block shape ( Figure 4 c). SEM images of the material after 20 weeks of hydrogen adsorption / desorption cycling ( Figure 4 (d, e) shows that only a few microcracks appeared on its surface, but no fragmentation or disintegration occurred; the alloy particles remained tightly bound together by a network of buffers and binders. Its macroscopic photographs ( Figure 4 f) also confirms that the entire block material maintained its initial shape and structural integrity, and no visible pulverization occurred.

[0072] The results of Example 1 show that by combining hydrogen storage alloy powder with a specific ratio of volume expansion buffer, thermally conductive material and additives, and then subjecting it to cold pressing and heat treatment, the prepared bulk solid hydrogen storage material can effectively suppress the pulverization phenomenon of the alloy during hydrogen absorption and desorption cycles, maintain the long-term integrity of the structure, and exhibit extremely high cycle stability and rapid kinetic performance.

[0073] Example 2

[0074] This embodiment 2 provides a hydrogen storage material whose composition and preparation process parameters are different from those of embodiment 1.

[0075] The hydrogen storage material provided in Example 2 consists of the following components by mass percentage: 9g of hydrogen storage alloy powder; 5g of volume expansion buffer; 4g of thermally conductive material; and 1g of additive. The composition and particle size requirements of the hydrogen storage alloy powder are the same as in Example 1, but the mass ratio of AB2 type to V-based BCC type hydrogen storage alloy is 1:4. The volume expansion buffer is polyether ester elastomer powder (particle size less than 200 mesh), the thermally conductive material is alumina powder (particle size less than 200 mesh), and the additive is polyimide.

[0076] The main steps of the hydrogen storage material preparation method provided in Example 2 are the same as those in Example 1, but the process parameters are adjusted as follows:

[0077] Cold pressing: The pressure is set to 3MPa and the holding time is 5min.

[0078] Heat treatment: carried out under a nitrogen (N2) atmosphere, at a heating temperature of 135℃, for 8 hours.

[0079] Performance Analysis:

[0080] The hydrogen storage material prepared in Example 2 was subjected to the same performance tests as in Example 1. The results showed that the hydrogen storage material provided in Example 2 also had good molding properties and excellent mechanical integrity. Thanks to the high content of volume expansion buffer and additives, the macroscopic morphology of the material remained almost unchanged after 20 hydrogen adsorption / desorption cycles. Figure 5 The figure shows a cross-sectional view of the hydrogen storage material after hydrogen absorption and desorption cycles. As can be seen from the figure, the hydrogen storage material described in Example 2 has fewer microcracks on its surface after hydrogen absorption and desorption cycles than that in Example 1, exhibiting better resistance to pulverization and structural stability. Figure 5 b shows the decrease in hydrogen storage capacity of the hydrogen storage material in Example 2 over time. Its hydrogen absorption capacity in the first cycle is 1.642, and after 20 cycles, the capacity decreases to 1.604, with a hydrogen storage capacity decay rate of less than 3%.

[0081] Example 3

[0082] This embodiment 3 provides a hydrogen storage material whose composition and preparation process parameters differ from those of embodiment 1.

[0083] The hydrogen storage material provided in Example 3 consists of the following components by mass percentage: 9.75g of hydrogen storage alloy powder; 0.1g of volume expansion buffer; 0.1g of thermally conductive material; and 0.05g of additives. The composition and particle size requirements of the hydrogen storage alloy powder are the same as in Example 1, but the mass ratio of AB2 type to V-based BCC type hydrogen storage alloy is 1:5. The volume expansion buffer is polyvinyl fluoride powder (particle size less than 200 mesh), the thermally conductive material is hexagonal boron nitride powder (particle size less than 200 mesh), and the additive is silane coupling agent KH551.

[0084] The main steps of the preparation method of the hydrogen storage material provided in Example 3 are the same as those in Example 1, but the process parameters are adjusted as follows:

[0085] Cold pressing: The pressure is set to 15MPa and the holding time is 30min.

[0086] Heat treatment: carried out under an argon (Ar) atmosphere, at a heating temperature of 150°C, for 12 hours.

[0087] Performance Analysis:

[0088] The hydrogen storage material prepared in Example 3 was subjected to the same performance tests as in Example 1. The results showed that even under the conditions of a hydrogen storage alloy content of 97.5% and a low additive content (1% or 0.5%), the prepared bulk material still maintained good structural integrity. After 20 hydrogen absorption and desorption cycles, the hydrogen storage material provided in Example 3 did not pulverize, and the capacity decay rate was controlled within 10%.

[0089] Example 4

[0090] This embodiment 4 provides a hydrogen storage material whose components are added in a composite manner.

[0091] The hydrogen storage material provided in Example 4 comprises the following components by mass percentage: 9.3g hydrogen storage alloy powder; 0.3g volume expansion buffer; 0.2g thermally conductive material; and 0.2g additive. The composition, ratio (1:3), and particle size requirements of the hydrogen storage alloy powder are the same as in Example 1. The volume expansion buffer is a composite buffer composed of low-density polyethylene and polyether ester elastomer mixed in a 1:1 mass ratio. The thermally conductive material is a composite thermally conductive agent composed of expanded graphite and alumina mixed in a 1:1 mass ratio. The additive is a composite additive composed of silane coupling agent KH551 and polyimide mixed in a 1:1 mass ratio.

[0092] The main steps of the preparation method of the hydrogen storage material provided in Example 4 are the same as those in Example 1, but the process parameters are adjusted as follows:

[0093] Cold pressing: pressure is 10MPa, holding time is 20min.

[0094] Heat treatment: carried out under a nitrogen (N2) atmosphere, at a heating temperature of 140℃, for a heating time of 6 hours.

[0095] Performance Analysis:

[0096] The hydrogen storage material prepared in Example 4 was subjected to the same performance tests as in Example 1. The results showed that the bulk material prepared using composite additives exhibited excellent overall performance. Its cycle stability was comparable to that of Example 1, with low capacity decay and good structural integrity.

[0097] Comparative Example

[0098] Comparative Example 1

[0099] Comparative Example 1 provides a hydrogen storage material composed of 9.5g of hydrogen storage alloy mixed powder, 0.2g of low-density polyethylene (LDPE) powder, and 0.3g of expanded graphite powder. Compared with Example 1, Comparative Example 1 does not contain the modified silane coupling agent KH551.

[0100] Comparative Example 1 provides a method for preparing a hydrogen storage material that is basically the same as the steps in Example 1: the three components are mixed uniformly by dry mechanical mixing; cold-pressed under a pressure of 5 MPa; and finally, subjected to constant temperature heat treatment at 120°C for 4 hours under an argon atmosphere, and the hydrogen storage material of Comparative Example 1 is obtained after cooling.

[0101] Performance Analysis

[0102] In Comparative Example 1, although the LDPE melted and flowed after heat treatment, the interfacial bonding between the hydrogen storage material prepared by the two phases was extremely weak due to the lack of a silane coupling agent to act as a "molecular bridge" between the hydrogen storage alloy (inorganic phase) and LDPE (organic phase). The prepared sample exhibited low mechanical strength and was relatively porous.

[0103] After 20 weeks of hydrogen adsorption / desorption cycling, significant material degradation was observed. Obvious crack propagation and edge spalling appeared after approximately 10 cycles. Figure 6 As shown in Figure a, after 20 weeks of hydrogen absorption and desorption cycling tests, most of the bulk material had broken into small pieces and contained a large amount of powder. After 20 weeks of hydrogen absorption cycling, the hydrogen storage capacity of the material rapidly decreased from 1.591 wt% to 1.187 wt%, with a capacity decay rate as high as 25%.

[0104] Comparative Example 2

[0105] Comparative Example 2 provides a hydrogen storage material with the same composition and proportions as Example 1: 9.45g of hydrogen storage alloy mixed powder, 0.2g of LDPE powder, 0.3g of expanded graphite powder, and 0.05g of modified silane coupling agent KH551.

[0106] Comparative Example 2 provides a method for preparing a hydrogen storage material, including the following steps:

[0107] After the above four components are dry-mixed, 0.5% of the total weight of pure water is sprayed evenly on the surface of the mixture and continuously turned and stirred; then, it is cold-pressed under a pressure of 5 MPa; finally, the pressed block material is placed in a vacuum drying oven and dried at 80°C for 4 hours to obtain the hydrogen storage material of Comparative Example 2.

[0108] Performance Analysis:

[0109] The hydrogen storage material provided in Comparative Example 2 failed to form the three-dimensional polymer network framework of Example 1 because the preparation temperature of 80°C is lower than the softening / melting temperature of LDPE, and the hydrolysis-condensation reaction of the silane coupling agent has low activity under these conditions. The curing of the hydrogen storage material provided in Comparative Example 2 relies solely on the physical accumulation between particles after the evaporation of trace amounts of moisture. The resulting sample has a loose texture, low mechanical strength, and is easily damaged even during transfer.

[0110] During the hydrogen storage performance test, the hydrogen storage material provided in Comparative Example 2 completely pulverized and disintegrated during the first activation process, making it impossible to conduct an effective cycle stability test. At the same time, the preparation process of spraying pure water to improve adhesion caused the surface of some BCC structure hydrogen storage alloy particles to be poisoned and lose hydrogen absorption activity, making them difficult to be effectively activated and significantly deteriorating the hydrogen storage performance of the material.

[0111] Comparative Example 3

[0112] Comparative Example 3 provides a hydrogen storage material, the raw material composition of which includes: 9.6g of hydrogen storage alloy mixed powder, 0.3g of polyvinyl alcohol (PVA) powder and 0.1g of natural graphite powder.

[0113] Comparative Example 3 provides a method for preparing a hydrogen storage material, comprising the following steps: mixing the above three components, spraying 1.0% of the total weight of the materials with pure water and stirring evenly; cold pressing under 10 MPa pressure; and finally drying under vacuum at 60°C for 4 hours.

[0114] Performance Analysis:

[0115] The hydrogen storage material prepared in Comparative Example 3 possessed certain initial mechanical strength. However, after 20 weeks of hydrogen absorption and desorption cycling tests, the material exhibited severe structural degradation. For example... Figure 7 As shown, the physical bonding network formed by PVA cannot effectively resist the repeated expansion stress of the hydrogen storage alloy, resulting in through-cracks appearing in the bulk material starting from the center, and the overall structure becoming loose. The hydrogen storage capacity decay rate is approximately 18%.

[0116] For those skilled in the art, other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, but obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this invention.

Claims

1. A hydrogen storage material, characterized by, The raw materials of the hydrogen storage material include the following components in percentage by mass: hydrogen storage alloy powder 90%-97.5%, volume expansion buffer 1%-5%, heat conducting material 1%-5%, and additive 0.5%-3%; the hydrogen storage alloy powder contains AB2 type hydrogen storage alloy and V-based BCC type hydrogen storage alloy, and the mass ratio of the AB2 type hydrogen storage alloy to the V-based BCC type hydrogen storage alloy is 1:3-5; the volume expansion buffer is low-density polyethylene; the heat conducting material is one or more of expanded graphite, aluminum oxide, and hexagonal boron nitride; and the additive is polyimide. The raw material components are mixed and cold-pressed to form a shape, and then heat-treated at a temperature of 110-150℃ for 4-12h under an inert atmosphere, and the hydrogen storage material is obtained after cooling.

2. A method of producing the hydrogen storage material according to claim 1, characterized by, The method comprises the following steps: The hydrogen storage alloy powder, volume expansion buffer, heat conducting material, and additive are mechanically mixed to obtain a precursor powder; and the precursor powder is cold-pressed to form a shape. The shaped material is heat-treated under an inert atmosphere, and then cooled to obtain the hydrogen storage material.

3. The production method according to claim 2, characterized by, The particle size of the hydrogen storage alloy powder is less than 10 mesh, and the particle sizes of the volume expansion buffer and the heat conducting material are both less than 200 mesh.

4. The preparation method according to claim 2, characterized in that, The pressure of the cold-pressing is 3-15MPa, and the pressure holding time is 5-30min.

5. The preparation method according to claim 2, characterized in that, The temperature of the heat treatment is 110-150℃, and the heating time is 4-12h.

6. The preparation method according to claim 2, characterized in that, The inert atmosphere is nitrogen or argon.

7. A hydrogen storage system characterized by, The hydrogen storage system contains the hydrogen storage material of claim 1, and is used in a proton exchange membrane fuel cell system.

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