Low-expansion high-stability alloy bed body suitable for large-particle-size hydrogen storage alloy and preparation method of low-expansion high-stability alloy bed body

Abstract

The invention relates to the technical field of hydrogen storage, and discloses a low-expansion high-stability alloy bed body suitable for a large-particle-size hydrogen storage alloy and a preparation method thereof.The hydrogen storage alloy bed body is prepared from, by mass, 85-96 parts of a hydrogen storage material, 4-5 parts of solder paste, 4-5 parts of an organic adhesive and 1-3 parts of a heat conduction material; the solder paste comprises the following raw materials in parts by mass: 88-90 parts of a liquid metal material, 4-8 parts of a soldering flux, 2-6 parts of a dispersing agent, 0.1-0.6 part of an active agent and 0.1-0.2 part of a thixotropic agent. According to the technical scheme, a large amount of heat generated by the hydrogen storage alloy in the hydrogen absorption process, especially heat generated by hydrogen absorption for the first time, is effectively utilized, and the phase change property of the liquid metal material is combined, so that the liquid metal material can be used as a binder to enhance the stability of the die bed body, and the mechanical property of the binder can also be enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen storage, and in particular to a low-expansion and high-stability alloy bed suitable for large-particle hydrogen storage alloys and a preparation method thereof. Background Art

[0002] The extensive use of fossil fuels has caused severe environmental pollution. Hydrogen, as a completely pollution-free green energy source, has attracted widespread attention. Of the three main links in hydrogen production, storage, transportation, and use, storage and transportation remains the most in need of technological innovation and development. Compared to high-pressure gaseous hydrogen storage and low-temperature liquid hydrogen storage, room-temperature solid hydrogen storage alloys, such as AB5-type rare earth alloys, AB2-type rare earth alloys, and vanadium-based BCC alloys, can reversibly store large amounts of hydrogen at room temperature. They offer advantages such as low storage pressure and high safety, and have broad application prospects.

[0003] However, solid-state hydrogen storage technology still faces the following challenges: (1) Hydrogen storage alloys, such as AB5 rare earth alloys, AB2 titanium alloys, and vanadium-based BCC alloys, release a large amount of heat during hydrogen absorption. Especially during the first hydrogen absorption, the temperature of the hydrogen storage alloy bed reaches over 100°C. How to effectively utilize heat and avoid damage to the container is the key to design. (2) The hydrogen storage material produces a huge volume expansion during hydrogen absorption, which generates stress on the wall of the hydrogen storage container and easily damages the container. During hydrogen absorption, hydrogen enters the alloy lattice, causing the lattice to expand. The expansion rate of AB5 rare earth alloys and AB2 titanium alloys reaches 20-30% during the first hydrogen absorption, and the first expansion of vanadium-based BCC hydrogen storage alloys reaches about 40%. When hydrogen desorbs from the lattice, it causes the lattice to shrink. During the reciprocating cycle of hydrogen absorption and desorption, the alloy will continue to pulverize into fine particles. In addition, during the expansion process, the alloy particles will generate huge stress on the wall of the hydrogen storage container; and the pulverized particles will be affected by gravity and the friction and extrusion between the particles, and will continue to compact and accumulate, resulting in local stress concentration. In summary, how to effectively reduce the expansion of the hydrogen storage container bed and the uniform distribution of particles is the key to ensuring the long life and safe operation of the hydrogen storage container. (3) In the preparation process of hydrogen storage alloy particles, it is necessary to add a crushing process to process the ingot alloy into smaller particles. However, in the crushing process, the smaller the particle size, the higher the crushing efficiency requirement of the equipment, and it is easy to cause oxidation of the alloy surface, resulting in alloy poisoning, difficulty in activation or reduced capacity.

[0004] To address these issues, researchers have conducted extensive research. Chinese patent CN114440123A discloses a hydrogen storage bed element for solid-state hydrogen storage tanks. The element utilizes 50 to 500 μm hydrogen storage alloy particles, two-liquid addition-type silicone gel, and graphite carbon powder. These materials are mixed and then pressed to create a low-expansion hydrogen storage alloy bed element. This element maintains its shape and a low mass loss rate after 200 cycles. Chinese patent CN115650157A discloses a high-thermal-conductivity, high-stability hydrogen storage alloy bed element for hydrogen storage tanks and its preparation process. The element utilizes 74 μm AB5-type LaNi5 hydrogen storage alloy particles, mixed with a PTFE binder, CMC wetting agent, and expanded graphite thermal conductor. The high-thermal-conductivity hydrogen storage alloy bed element is then pressed and dried to create the desired shape. The element maintains its shape after 20 cycles of hydrogen absorption and desorption. Chinese patent CN117430081A discloses a hydrogen storage alloy block material for filling solid-state hydrogen storage devices. It uses an AB2-type Ti-based hydrogen storage alloy ground to 100-400 mesh (i.e., 37 ~ 150 μm), mixed with polyvinyl alcohol binder, molybdenum disulfide additive, and natural 50-mesh flake graphite powder thermal conductor. The mixture is then sprayed with water and turned evenly again. Finally, it is cold pressed and dried to obtain a block. After 50 cycles of hydrogen absorption and desorption, the alloy block does not show any significant changes.

[0005] The above patented technologies all use small-particle hydrogen storage alloys to prepare the bed. However, the expansion of coarser-particle hydrogen storage alloys during the hydrogen absorption process is greater than that of smaller-particle hydrogen storage alloys, which will cause greater squeezing force on the hydrogen storage container. In addition, the pulverization process and stress accumulation of coarser-particle hydrogen storage alloys during the circulation process are more obvious, which is not conducive to maintaining the shape stability of the bed. The large amount of heat generated during the first hydrogen absorption process will affect the hydrogen absorption rate of the alloy. At the same time, the large amount of heat generated in a short period of time will reduce the adhesion of ordinary organic binders, affecting the bonding effect. Therefore, it is particularly important to provide a highly stable hydrogen storage alloy bed technology for large-sized hydrogen storage alloys that can rationally utilize the large amount of heat released by the hydrogen storage alloy when absorbing hydrogen. Summary of the Invention

[0006] The present invention aims to provide a low-expansion, high-stability alloy bed suitable for large-particle hydrogen storage alloys and a preparation method thereof, so as to solve the problems of unsatisfactory bed stability and hydrogen absorption rate in the prior art for preparing hydrogen storage alloy beds from large-particle alloy materials.

[0007] To achieve the above-mentioned purpose, the present invention adopts the following technical solution: a low-expansion, high-stability alloy bed suitable for large-particle hydrogen storage alloys, comprising the following raw materials, in parts by mass: 85-96 parts of hydrogen storage material, 4-5 parts of solder paste, 4-5 parts of organic adhesive, and 1-3 parts of thermal conductive material; the solder paste comprises the following raw materials, in parts by mass: 88-90 parts of liquid metal material, 4-8 parts of flux, 2-6 parts of dispersant, 0.1-0.6 parts of activator, and 0.1-0.2 parts of thixotropic agent.

[0008] Preferably, as an improvement, the hydrogen storage material is at least one of titanium AB2 type, titanium AB type, rare earth AB3, rare earth AB5 type, vanadium-based solid solution type, and magnesium-based hydrogen storage alloy.

[0009] Preferably, as an improvement, the hydrogen storage material is in powder form, and the average particle size of the hydrogen storage material is ≤3.2 mm.

[0010] Preferably, as an improvement, the average particle size of the hydrogen storage material is 1-2 mm.

[0011] Preferably, as an improvement, the organic adhesive is at least one of epoxy resin, polyurethane, silicone rubber, polyethylene, acrylic acid, and inorganic ceramic glue, and the viscosity of the organic adhesive is 4000-6000 cps.

[0012] Preferably, as an improvement, the thermally conductive material is a metal thermally conductive material or a carbon-based thermally conductive material, including at least one of aluminum powder, copper powder, graphene, graphite carbon powder, expanded graphite, flake graphite, and acetylene black.

[0013] Preferably, as an improvement, the thermal conductive material is flake graphite, and the amount of the thermal conductive material added is 1-3 wt%.

[0014] Preferably, as an improvement, the flux is modified rosin; the dispersant is one or more of isopropyl alcohol and diethylene glycol hexyl ether; the activator is one or more of DL-malic acid, succinic acid, and adipic acid; and the thixotropic agent is one or more of amide oligomers and sodium lauryl sulfate.

[0015] Preferably, as an improvement, a method for preparing a low expansion and high stability alloy bed suitable for large-particle hydrogen storage alloys comprises the following steps: Step I: uniformly mixing solder paste and organic adhesive to obtain system I; Step II, adding hydrogen storage material to system I and mixing evenly to obtain system II; Step III, adding thermal conductive material to system II and mixing evenly to obtain system III; Step IV: Place the system III into a mold, press to obtain a block of hydrogen storage bed elements, and solidify to obtain a solid hydrogen storage bed.

[0016] Preferably, as an improvement, in step IV, the pressure is 400-650 MPa, and the pressure is maintained for 60 seconds, and the curing condition is standing at room temperature for 24 hours.

[0017] The principle and advantages of this solution are as follows: In practical application, in order to address the problems of existing large-particle hydrogen storage alloy beds due to poor structural stability, high processing energy consumption, and rapid cycle attenuation, this solution innovatively constructs a quaternary composite system of hydrogen storage material - liquid metal - organic binder - thermal conductive material. Through liquid metal phase transition and multi-interface synergy, the systemic optimization of bed performance is achieved. The specific mechanism of action is divided into three stages of evolution: (1) Initial phase change control stage (first cycle of hydrogen absorption and desorption) Liquid metal is preformed into a solder paste. The heat released by the hydrogen storage alloy upon hydrogen absorption (especially the significant temperature rise during initial hydrogen absorption) triggers a solid-liquid phase transition between the solder paste microspheres at 80-100°C. Leveraging surface tension and capillary action, the molten metal rapidly penetrates the interstices between the hydrogen storage particles, forming a "liquid infiltration layer." This fills the micropores and defects between the particles, improving the interfacial bonding between the hydrogen storage material and the binder and reducing interfacial thermal resistance. Furthermore, the liquid metal's fluidity allows it to "adaptively" fill the initial pores in the bed, initially establishing a flexible interconnecting network and mitigating the intense volume expansion stress associated with initial hydrogen absorption.

[0018] (2) Mid-term structural strengthening stage (cycle 10-25 times) As the cycle progresses, the solidified liquid metal and the organic binder (polyolefin-based) undergo molecular-level interpenetration and synergy: the metal network forms an interpenetrating polymer network (IPN) with the polyolefin chains through physical entanglement and chemical bonding (such as metal-polymer coordination bonds). This structure increases the binder modulus by 45%-60%, upgrading it from a "flexible bond" to a "rigid and flexible" mechanical support system. This system not only buffers the cyclic expansion strain of the hydrogen storage particles through the organic phase, but also resists macroscopic deformation of the bed through the high strength of the metal network, effectively suppressing cracking and pulverization of the bed caused by cyclic stress.

[0019] (3) Long-cycle dynamic buffering stage (cycle more than 25 times) The cyclical phase transition of liquid metal (melting upon hydrogen absorption - solidification upon hydrogen release) is a key advantage: during hydrogen absorption, the metal melts and absorbs expansion strain energy, preventing strain concentration; during hydrogen release, the metal solidifies, releasing stored energy and reconstructing the support network. This "dynamic stress buffering mechanism" continuously offsets the cyclic volume changes of the hydrogen storage alloy, maintaining a state of "controllable fluctuation" in the bed's internal stress, rather than the "accumulative stress growth" of traditional systems. This fundamentally slows down the structural degradation of the bed.

[0020] During the technical research and development phase, this technical solution employed a solder paste containing liquid metal for mixed compaction. The selection of solder paste and organic binder types and their addition ratio were key considerations. Solder paste and organic binders exhibit a strong synergistic effect, and at a specific addition ratio, liquid metal particles can enhance the mechanical properties of the organic binder. During the research and development phase, the inventors also attempted compaction using conventional liquid metal (gallium-indium-tin alloy), but this did not achieve the desired effect.

[0021] The effects of this technical solution are: (1) Innovative utilization of thermal-mechanical coupling (synergy between process and performance): Breaking through the traditional “passive heat dissipation + rigid bonding” approach, the process actively utilizes the residual heat of hydrogen absorption by hydrogen storage alloys to drive the phase transformation of liquid metal. The phase transformation process is both a “thermal energy-structural energy” conversion (melting filling / solidification strengthening) and a “dynamic regulation of mechanical properties” process (liquid buffer / solid support). This coupling mechanism enables liquid metal to play the dual roles of “binder reinforcement phase” and “thermal management medium”, solving the synergistic problem of “poor thermal conductivity + easy pulverization” of large-particle bed.

[0022] (2) Process innovation for large-scale production: Aiming at the industrial demand for large-particle alloys (1-2 mm), the traditional fine powder (≤500 μm) fine crushing process is abandoned: From the perspective of "material processing loss": it avoids surface oxidation and lattice defect introduction of hydrogen storage alloys during the crushing process (traditional crushing causes a sharp increase in specific surface area and an oxidation loss rate of over 5%), and retains the intrinsic hydrogen storage activity of the alloy; From the perspective of "energy consumption and efficiency": processing energy consumption is reduced by about 40% (the crushing process accounts for more than 60% of the energy consumption of traditional processes), and the production cycle is shortened by 30%-40%, which is suitable for the "large-scale, low-cost" industrial preparation needs and clears the process obstacles for the large-scale application of solid-state hydrogen storage.

[0023] (3) Systematic improvement of service safety and lifespan: Through the triple effects of "suppressing expansion, alleviating pulverization, and optimizing thermal conductivity", the core pain points of long-term service of hydrogen storage beds are solved: Expansion control: The liquid metal network constrains the expansion direction of the hydrogen storage particles (from "disordered expansion" to "directional deformation along the metal network"). After 50 cycles, the axial expansion rate is controlled within 13.95% - 25.05%, which is 30% - 55% lower than the control, thus preventing fatigue cracking of the tank body due to stress concentration. Pulverization suppression: The interpenetrating network structure "wrapped" the hydrogen storage particles, reducing mechanical collision and peeling between particles during circulation. The mass loss rate was only 0.04% - 0.39% (traditional binder systems exceed 12%), fundamentally delaying the vicious cycle of "pulverization-reduced thermal conductivity-thermal runaway"; Enhanced thermal management: Liquid metal itself has high thermal conductivity. Combined with phase change heat conduction and network structure, the thermal conductivity of the bed reaches 4.09 W / (m•K) (traditional systems are less than 2 W / (m•K)), ensuring temperature uniformity during the hydrogen storage / dehydrogenation process and avoiding alloy degradation caused by local overheating.

[0024] (4) Verification of the synergistic advantages of the quaternary system: By optimizing the ratio (the ratio of Example 1 is 5.4:0.3:0.24:0.06), the synergistic optimization of "dimensional stability-thermal conductivity-cycle life" is achieved: Dimensional stability: The interpenetrating structure of the metal network and the organic phase enables the bed to maintain "macro-morphology controllability" during circulation, solving the problem of large particle size bed prone to collapse and deformation; Thermal conductivity: The high thermal conductivity of liquid metal and the synergy of thermal conductive materials create a "three-dimensional thermal network," which more than doubles the thermal response speed of traditional systems and meets the thermal management requirements of fast hydrogen charging scenarios. Attenuation suppression: Dynamic stress buffering and interface optimization reduce the attenuation rate of the hydrogen storage module to only 7.6 wt% after 50 cycles (pure alloy attenuation is 10.6 wt%), delaying performance attenuation from the dual dimensions of "material-structure" and breaking through the bottleneck of long-term circulation of solid-state hydrogen storage.

[0025] In summary: This solution systematically solves the three major problems of processing bottlenecks, structural degradation, and insufficient thermal management of large-particle hydrogen storage beds through the "dynamic regulation" of liquid metal phase transitions and the "co-design" of quaternary systems. It provides a feasible technical path for solid-state hydrogen storage technology to move from "laboratory demonstration" to "industrial application", and has the triple value of "process innovation, performance breakthrough, and cost optimization". BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 3. This is a comparison diagram of the morphology before and after the cycle of Example 1 of the present invention.

[0027] Figure 2 These are the PCT curves of Example 1 of the present invention after 50 cycles, namely the 1st hydrogen desorption, the 10th hydrogen desorption, the 25th hydrogen desorption, and the 50th hydrogen desorption.

[0028] Figure 3 This is a low-magnification SEM image of Example 1 of the present invention before cycling.

[0029] Figure 4 (a) A high-magnification SEM image and (b) an EDS element distribution map of Example 1 of the present invention before cycling.

[0030] Figure 5 This is a low-magnification SEM image of Example 1 of the present invention after 5 cycles.

[0031] Figure 6(a) A high-magnification SEM image and (b) EDS element distribution map of Example 1 of the present invention after 5 cycles.

[0032] Figure 7 This is a low-magnification SEM image of Example 1 of the present invention after 10 cycles.

[0033] Figure 8 (a) A high-magnification SEM image and (b) EDS element distribution map of Example 1 of the present invention after 10 cycles.

[0034] Figure 9 This is a low-magnification SEM image of Example 1 of the present invention after 25 cycles.

[0035] Figure 10 (a) A high-magnification SEM image and (b) EDS element distribution map of Example 1 of the present invention after 25 cycles.

[0036] Figure 11 This is a low-magnification SEM image of Example 1 of the present invention after 50 cycles.

[0037] Figure 12 (a) A high-magnification SEM image and (b) EDS element distribution map of Example 1 of the present invention after 50 cycles.

[0038] Figure 13 This is a comparison diagram of the morphology before and after the cycle of Example 2 of the present invention.

[0039] Figure 14 This is a comparison diagram of the morphology before and after the cycle of Example 3 of the present invention.

[0040] Figure 15 This is a comparison diagram of the morphology before and after the cycle of Example 4 of the present invention.

[0041] Figure 16 This is a comparison diagram of the morphology before and after the cycle of Example 5 of the present invention.

[0042] Figure 17 3. This is a comparison diagram of the morphology before and after the cycle of Example 6 of the present invention.

[0043] Figure 18 3. This is a comparison diagram of the morphology before and after the cycle of Example 7 of the present invention.

[0044] Figure 19 Comparison of the morphology before and after the cycle of Example 8 of the present invention Figure 20 This is a comparison diagram of the morphology before and after the cycle of Comparative Example 1 of the present invention.

[0045] Figure 21 This is a comparison diagram of the morphology before and after the cycle of Comparative Example 2 of the present invention.

[0046] Figure 22This is a comparison diagram of the morphology before and after the cycle of Comparative Example 3 of the present invention.

[0047] Figure 23 This is a comparison diagram of the morphology before and after the cycle of Comparative Example 4 of the present invention.

[0048] Figure 24 This is a comparison diagram of the morphology before and after the cycle of Comparative Example 5 of the present invention.

[0049] Figure 25 The PCT curves of Comparative Example 6 of the present invention after 50 cycles, including the first, 10th, 25th and 50th hydrogen desorption times.

[0050] Figure 26 This is a comparison diagram of the morphology before and after the cycle of Comparative Example 7 of the present invention. DETAILED DESCRIPTION

[0051] The following is further described in detail through specific embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; and the materials, reagents, etc. used are all commercially available.

[0052] Program Overview: A low-expansion, high-stability alloy bed suitable for large-particle hydrogen storage alloys comprises the following raw materials, measured in parts by mass: 85-96 parts of hydrogen storage material, 4-5 parts of solder paste, 4-5 parts of organic adhesive, and 1-3 parts of thermal conductive material; the solder paste comprises the following raw materials, measured in parts by mass: 88-90 parts of liquid metal material, 4-8 parts of soldering flux, 2-6 parts of dispersant, 0.1-0.6 parts of activator, and 0.1-0.2 parts of thixotropic agent.

[0053] The hydrogen storage material is at least one of a titanium AB2 type, a titanium AB type, a rare earth AB3 type, a rare earth AB5 type, a vanadium-based solid solution type, and a magnesium-based hydrogen storage alloy. The hydrogen storage material is in powder form, and the average particle size of the hydrogen storage material is ≤3.2 mm, preferably 1-2 mm.

[0054] The liquid metal material in the solder paste is a single substance or alloy of gallium, indium, tin, bismuth, lead, and silver.

[0055] The organic adhesive is at least one of epoxy resin, polyurethane, silicone rubber, polyethylene, acrylic acid, and inorganic ceramic adhesive. The organic adhesive has a viscosity of 4000-6000 cps, is stable at 0-120°C, and does not react with the hydrogen storage material, liquid metal material, or thermal conductive material. Polyethylene adhesive is preferred.

[0056] The thermally conductive material is a metal thermally conductive material or a carbon-based thermally conductive material, including at least one of aluminum powder, copper powder, graphene, graphite carbon powder, expanded graphite, flake graphite, and acetylene black. Flake graphite is preferred, and the amount of flake graphite added is 1-3 wt%.

[0057] The flux is modified rosin; The dispersant is one or more of isopropyl alcohol and diethylene glycol hexyl ether; The active agent is one or more of DL-malic acid, succinic acid, and adipic acid; The thixotropic agent is one or more of amide oligomer and sodium lauryl sulfate.

[0058] A method for preparing a low-expansion, high-stability alloy bed suitable for large-particle hydrogen storage alloys comprises the following steps: Step I: uniformly mixing the solder paste and the organic adhesive according to a mass ratio to obtain System I; Step II, adding hydrogen storage material to system I and mixing evenly to obtain system II; Step III, adding thermal conductive material to system II and mixing evenly to obtain system III; Step IV: Place system III into a mold and press to obtain a block of hydrogen storage bed components at a pressure of 400-650 MPa for 60 seconds. Let it stand at room temperature for 24 hours to obtain a solid hydrogen storage bed.

[0059] Example 1 A low-expansion, high-stability alloy bed suitable for large-particle hydrogen storage alloys. The raw materials include: 5.4 g of vanadium-based BCC hydrogen storage alloy with a particle size of 1-2 mm, 0.3 g of polyethylene glue, 0.24 g of solder paste, and 0.06 g of 50-mesh flake graphite powder. The mass percentage of each raw material is vanadium-based BCC hydrogen storage alloy: polyethylene glue: solder paste: 50-mesh flake graphite powder = 90:5:4:1 (wt%).

[0060] The solder paste includes the following raw materials in parts by mass: 88-89 parts of liquid metal material, 6.3 parts of flux, 5 parts of dispersant, 0.5 parts of activator, and 0.2 parts of thixotropic agent.

[0061] The dispersant is isopropyl alcohol; the active agent is succinic acid; and the thixotropic agent is sodium lauryl sulfate.

[0062] A method for preparing a low-expansion, high-stability alloy bed suitable for large-particle hydrogen storage alloys comprises the following steps: Step I: uniformly mix the solder paste and the polyethylene adhesive according to a mass ratio to obtain System I; Step II: adding a vanadium-based BCC hydrogen storage alloy to system I and mixing uniformly to obtain system II; Step III, adding 50 mesh flake graphite powder to system II and mixing evenly to obtain system III; Step IV: Place system III into a mold and press to obtain a block of hydrogen storage bed components at a pressure of 623 MPa, maintaining the pressure for 60 seconds. Allow to stand at room temperature for 24 hours to obtain a solid hydrogen storage bed.

[0063] Example 2 The difference between this embodiment and Example 1 is that: in this embodiment, no thermal conductive material flake graphite powder is added, and a low-expansion and high-stability alloy bed suitable for large-particle hydrogen storage alloys is prepared. The raw materials include: 5.46 g of vanadium-based BCC hydrogen storage alloy, 0.3 g of polyethylene glue, and 0.24 g of solder paste. The mass percentage of each raw material is vanadium-based BCC hydrogen storage alloy: polyethylene glue: solder paste: = 91:5:4 (wt%).

[0064] Example 3 The difference between this embodiment and Example 1 is that: in this embodiment, a low-expansion, high-stability alloy bed suitable for large-particle hydrogen storage alloys is provided, and the raw materials include: 5.4 g of vanadium-based BCC hydrogen storage alloy with a particle size of 1-2 mm, 0.24 g of polyethylene glue, 0.3 g of solder paste, and 0.06 g of 50-mesh flake graphite powder, and the mass percentage of each raw material is vanadium-based BCC hydrogen storage alloy: polyethylene glue: solder paste: 50-mesh flake graphite powder = 90:4:5:1 (wt%).

[0065] Example 4 The difference between this embodiment and Example 1 is that: in this embodiment, no thermal conductive material flake graphite powder is added, and the organic adhesive is polyurethane glue. Specifically, a low-expansion and high-stability alloy bed suitable for large-particle hydrogen storage alloys, the raw materials include: 5.4 g of vanadium-based BCC hydrogen storage alloy with a particle size of 1-2 mm, 0.24 g of polyurethane glue, and 0.36 g of solder paste, and the mass percentage of each raw material is vanadium-based BCC hydrogen storage alloy: polyurethane glue: solder paste = 90:4:6 (wt%).

[0066] Example 5 The difference between this embodiment and Example 1 is that: in this embodiment, no thermal conductive material flake graphite powder is added, and a low-expansion, high-stability alloy bed suitable for large-particle hydrogen storage alloys is prepared. The raw materials include: 5.4 g of vanadium-based BCC hydrogen storage alloy with a particle size of 1-2 mm, 0.3 g of polyethylene glue, and 0.3 g of solder paste. The mass percentage of each raw material is vanadium-based BCC hydrogen storage alloy: polyethylene glue: solder paste = 90:5:5 (wt%).

[0067] Example 6 The difference between this embodiment and Example 1 is that: in this embodiment, the mass of the added thermal conductive material is 0.12 g, and the raw materials of a low-expansion, high-stability alloy bed suitable for large-particle hydrogen storage alloys include: 5.34 g of vanadium-based BCC hydrogen storage alloy, 0.3 g of polyethylene glue, 0.24 g of solder paste, and 0.12 g of 50-mesh flake graphite powder. The mass percentage of each raw material is vanadium-based BCC hydrogen storage alloy: polyethylene glue: solder paste: 50-mesh flake graphite powder = 89:5:4:2 (wt%).

[0068] Example 7 The difference between this embodiment and Example 1 is that: in this embodiment, the mass of the added thermal conductive material is 0.18 g, and the raw materials of a low-expansion, high-stability alloy bed suitable for large-particle hydrogen storage alloys include: 5.28 g of vanadium-based BCC hydrogen storage alloy, 0.3 g of polyethylene glue, 0.24 g of solder paste, and 0.18 g of 50-mesh flake graphite powder. The mass percentage of each raw material is vanadium-based BCC hydrogen storage alloy: polyethylene glue: solder paste: 50-mesh flake graphite powder = 88:5:4:3 (wt%).

[0069] Example 8 The difference between this embodiment and Example 1 is that: in this embodiment, no thermal conductive material flake graphite powder is added, and a low-expansion and high-stability alloy bed suitable for large-particle hydrogen storage alloys is prepared. The raw materials include: 5.52 g of vanadium-based BCC hydrogen storage alloy, 0.24 g of polyethylene glue, and 0.24 g of solder paste. The mass percentage of each raw material is vanadium-based BCC hydrogen storage alloy: polyethylene glue: solder paste: = 92:4:4 (wt%).

[0070] Comparative Example 1 This comparative example differs from Example 1 in that the hydrogen storage alloy bed in this comparative example is made from 5 g of a vanadium-based BCC hydrogen storage alloy with a particle size of 1-2 mm and 1 g of polyethylene glue. The weight percentage of the raw materials in this comparative example is 90:10 (wt%).

[0071] Comparative Example 2 This comparative example differs from Example 1 in that the hydrogen storage alloy bed in this comparative example is made from raw materials including: 5.4 g of vanadium-based BCC hydrogen storage alloy with a particle size of 1-2 mm, and 0.6 g of solder paste. The weight percentage of the raw materials in this comparative example is 90:10 (wt%).

[0072] Comparative Example 3 The difference between this comparative example and Example 1 is that in this comparative example, the raw materials for the hydrogen storage alloy bed include: 5.4 g of vanadium-based BCC hydrogen storage alloy with a particle size of 1-2 mm, 0.24 g of inorganic ceramic glue, and 0.36 g of solder paste. The mass percentage of each raw material in this comparative example is vanadium-based BCC hydrogen storage alloy: inorganic ceramic glue: solder paste = 90:4:6 (wt%) Comparative Example 4 This comparative example differs from Example 1 in that the hydrogen storage alloy bed in this comparative example is made from the following raw materials: 5.4 g of vanadium-based BCC hydrogen storage alloy with a particle size of 1-2 mm, 0.24 g of silicone rubber glue, and 0.36 g of solder paste. The weight percentages of the raw materials in this comparative example are vanadium-based BCC hydrogen storage alloy: silicone rubber glue: solder paste = 90:4:6 (wt%).

[0073] Comparative Example 5 This comparative example differs from Example 1 in that the raw materials for the hydrogen storage alloy bed in this comparative example include: 5.4 g of vanadium-based BCC hydrogen storage alloy with a particle size of 1-2 mm, 0.24 g of silicone gel glue, and 0.36 g of solder paste. The weight percentages of the raw materials in this comparative example are vanadium-based BCC hydrogen storage alloy: silicone gel glue: solder paste = 90:4:6 (wt%).

[0074] Comparative Example 6 The difference between this comparative example and Example 1 is that in this comparative example, the hydrogen storage alloy bed is composed only of vanadium-based hydrogen storage alloy particles, which are not pressed but directly piled up in the reactor.

[0075] Comparative Example 7 Weigh 5.4 g of vanadium-based BCC hydrogen storage alloy with a particle size of 1-2 mm and 0.6 g of gallium-indium-tin alloy. This comparative example differs from Example 1 in that the mass percentage of each raw material is vanadium-based BCC hydrogen storage alloy: liquid metal = 90:10 (wt%).

[0076] After mixing the vanadium-based BCC hydrogen storage alloy and the indium-tin-bismuth alloy, place them in a gallium mold and form them into a shape. Since the melting point of the gallium-indium-tin alloy is about 29°C, it is liquid at room temperature and has no adhesive effect. Therefore, it cannot be pressed into shape. The state after mixing and the state of the block are shown in the figure. Figure 23 .

[0077] The parameter settings of the above embodiments and comparative examples are summarized in Table 1: the addition ratio refers to the mass percentage of hydrogen storage material, organic adhesive, solder paste and thermal conductive material.

[0078] Table 1

[0079] Experimental Example 1 The hydrogen storage alloy beds prepared in the above examples and comparative examples were completely activated in a reactor at 80°C for 3 hours in vacuum. The cycle was 30 minutes of hydrogen absorption at 0°C and 30 minutes of vacuum at 50°C. After 5 cycles, the beds were taken out to measure the diameter and height, and the expansion rate was calculated. The diameter and height comparison of each of Examples 1 to 8 and Comparative Examples 1 to 5 and Comparative Example 7 before and after the cycle are shown in the figure below. Figure 1 、 Figure 13 、 Figure 14 、 Figure 15 、 Figure 16 、 Figure 17 、 Figure 18 、 Figure 19 、 Figure 20 、 Figure 21 shown.

[0080] The volume and mass before and after hydrogen absorption were measured, and the mass of alloy used in each hydrogen storage bed element was recorded. The hydrogen storage mass of the alloy in each compact was calculated based on a hydrogen storage capacity of 2.3 wt%. Thermal conductivity (GB / T 10294) was used as the test standard.

[0081] Volume hydrogen storage density (kg / m 3 ) = single block hydrogen storage mass (kg) / single block volume (m 3 ) ; Mass hydrogen storage density (wt.%) = single block hydrogen storage mass (kg) / single block total mass (kg); Volume expansion rate (%) = (volume after hydrogen absorption (m 3 ) - Volume before hydrogen absorption (m 3 )) / Volume before hydrogen absorption (m 3 ) ; Mass loss rate (%) = (mass before hydrogen absorption (kg) - mass after hydrogen absorption (kg)) / mass before hydrogen absorption (kg). The results of radial expansion rate, axial expansion rate, volume expansion rate, and mass loss rate are shown in Table 2. The results show that simply adding polyethylene glue or solder paste to the block will cause a large cyclic volume expansion of the hydrogen storage bed components and a high mass loss rate. By adjusting the ratio of the two, the volume expansion rate of the hydrogen storage bed components can be effectively reduced and the mass hydrogen storage density can be improved.

[0082] Specifically, after 50 cycles of hydrogen absorption and desorption, the hydrogen storage alloy bed maintained good shape with minimal mass loss. Its radial expansion was 9.45%, axial expansion was 13.95%, volume was 42.48%, and mass loss was 0.38%. The conductivity of the sample was 0.09 W / (m·K). Low-magnification SEM images before cycling showed Figure 3 , high magnification SEM and EDS spectrum are shown in Figure 4; Low magnification SEM after 5 cycles Figure 5 , high magnification SEM and EDS spectrum are shown in Figure 6 ; Low-magnification SEM after 10 cycles Figure 7 , high magnification SEM and EDS spectrum are shown in Figure 8 ; Low-magnification SEM after 25 cycles Figure 9 , high magnification SEM and EDS spectrum are shown in Figure 10 ; Low magnification SEM after 50 cycles Figure 11 , high magnification SEM and EDS spectrum are shown in Figure 12 .

[0083] After five cycles of hydrogen absorption and desorption, the hydrogen storage alloy bed maintained its shape and exhibited minimal mass loss. Its radial expansion was 8.3%, its axial expansion was 15.52%, its volumetric expansion was 44.53%, and its mass loss was 0.39%. The thermal conductivity of the sample was 2.71 W / (m·K).

[0084] After five cycles of hydrogen absorption and desorption, the hydrogen storage alloy bed maintained good shape and had minimal mass loss. The radial expansion rate was 8.84%, the axial expansion rate was 15.76%, the volume expansion rate was 45.86%, and the mass loss rate was 0.04%. The thermal conductivity of the sample was 3.72 W / (m·K). After five cycles of hydrogen absorption and desorption, the hydrogen storage alloy bed maintained its shape well, with radial expansion of 15.6%, axial expansion of 8.3%, volumetric expansion of 81.77%, and mass loss of 0.03%. The thermal conductivity of the sample was 3.34 W / (m·K).

[0085] After five cycles of hydrogen absorption and desorption, the hydrogen storage alloy bed maintained its shape well. Its radial expansion was 25.05%, its axial expansion was 12.62%, its volume expansion was 58.61%, and its mass loss was 0.08%. The thermal conductivity of the sample was 3.04 W / (m·K).

[0086] Example 6 After five cycles of hydrogen absorption and desorption, the hydrogen storage alloy bed maintained good shape and had minimal mass loss. Its radial expansion was 10.66%, and its axial expansion was 15.21%. The thermal conductivity of the sample was 5.31 W / (m·K).

[0087] Example 7 After five cycles of hydrogen absorption and desorption, the hydrogen storage alloy bed in Example 7 maintained its shape and exhibited minimal mass loss. Its radial expansion was 11.14%, its axial expansion was 20.86%, its volumetric expansion was 49.29%, and its mass loss was 1.72%. The thermal conductivity of the sample was 6.49 W / (m·K).

[0088] Example 8 After five cycles of hydrogen absorption and desorption, the hydrogen storage alloy bed in Example 8 maintained its shape and exhibited minimal mass loss. Its radial expansion was 13.44%, its axial expansion was 30.09%, its volumetric expansion was 67.39%, and its mass loss was 0.98%. The thermal conductivity of the sample was 3.37 W / (m·K).

[0089] After 5 cycles of hydrogen absorption and desorption in Comparative Example 1, the hydrogen storage alloy bed showed obvious powder loss, with a radial expansion rate of 18.63%, an axial expansion rate of 13.62%, a volume expansion rate of 59.89%, and a mass loss rate of 12.01%.

[0090] The hydrogen storage alloy bed of Comparative Example 2 could no longer maintain its original shape and had a significant mass loss. The remaining portion had a radial expansion rate of 16.21%, an axial expansion rate of 12.91%, a volume expansion rate of 52.48%, and a mass loss rate of 22.1%.

[0091] The remaining portion of Comparative Example 3 exhibited a radial expansion rate of 17.31%, an axial expansion rate of 30.96%, a volume expansion rate of 80.21%, and a mass loss rate of 7.27%. The thermal conductivity of the sample was 3.43 W / (m·K).

[0092] After 5 cycles of hydrogen absorption and desorption in Comparative Examples 4-5 and Comparative Example 7, the samples were completely broken into irregular blocks, and the mass loss rate and volume expansion change could not be calculated.

[0093] Comparative Example 6 was pulverized and broken into fine particles after 5 cycles of hydrogen absorption and desorption.

[0094] Table 2 Comparison of pulverization degree and mass loss rate of hydrogen storage bed components after 5 cycles of hydrogen absorption and desorption

[0095] Table 3 Comparison of the degree of pulverization and mass loss rate of hydrogen storage bed components after 5 cycles of hydrogen absorption and desorption

[0096] Experimental Example 2 Microstructure Characterization The hydrogen storage alloy beds prepared in the above embodiments and comparative examples were subjected to 50 cycles of hydrogen absorption and desorption, and the microstructures before and after the cycles were tested. The results were as follows: Figure 3-21 The results show that before hydrogen absorption, the solder paste appears uniformly spherical under SEM; after five cycles, it has melted into a uniform, amorphous state. The morphology and element distributions demonstrate that the solder paste undergoes significant melting and resolidification during hydrogen absorption and desorption, strengthening the bed structure.

[0097] SEM characterization results before and after the cycle of Example 1 ( Figure 3-12 ) shows that the melting-solidification effect of liquid metal in the process of hydrogen absorption and heat release is effective: (1) Initial stage (5 cycles): Solder paste microspheres undergo solid-liquid phase transition at 80-100℃ ( Figure 5 ,6), the molten metal forms a liquid infiltration in the gap between the particles, and improves the interface bonding state through capillary action; (2) mid-stage (25 cycles): the solidified metal network forms an interpenetrating polymer network with the polyolefin ( Figure 9 ,10), which increases the binder modulus by 45%-60%, effectively resisting cyclic stress; (3) Long cycle stage (50 cycles): Periodic phase change process of liquid metal ( Figure 11 ,12) Continuously release / absorb expansion strain energy to form a dynamic stress buffer mechanism. The SEM characterization results of Examples 2-5 are as follows Figure 13-16 shown.

[0098] Experimental Example 3: Hydrogen Absorption and Desorption Capacity Fading Test The hydrogen storage alloy beds of Example 1 and Comparative Example 6 were subjected to capacity fade tests. The experimental method was as follows: the cycles were tested using the MH-PCT hydrogen storage alloy tester of the Beijing Nonferrous Metals Research Institute, and the microstructure was tested using the Hitachi SU8200. The cycles were performed in the following manner: the volume of the sample was first calibrated with high-purity argon at room temperature, and the sample was activated by vacuuming in a constant temperature water bath at 80°C for 2 h. Hydrogen was absorbed for 60 min in a constant temperature water bath of 0°C and a pressure of 9.0 MPa for the 1st, 26th, and 50th times. Hydrogen desorption PCT was performed in a constant temperature water bath of 50°C and a pressure of 9.0 MPa for the 1st, 26th, and 50th times as a basis for evaluating capacity fade. For the remaining times, hydrogen absorption was performed for 4 min at room temperature for hydrogen absorption kinetics, and vacuuming was performed at room temperature for 5 min. A total of 50 cycles were performed.

[0099] The test results are as follows Figure 2 as well as Figure 25 As shown in the figure, the results show that, for Example 1 of the present invention, the hydrogen release rate gradually decreases with increasing cycle number, with a relatively gentle decay. In contrast, the hydrogen release rate for Comparative Example 6 continues to decrease with increasing cycle number, with a more pronounced decay in the later stages (25 to 50 cycles), resulting in a faster overall decay rate. The pressure trends for Example 1 and Comparative Example 6 are similar during the initial cycle (the first cycle). However, the pressure drop for the Comparative Example 6 is more significant as the cycle number increases, indicating that the hydrogen release stability of Comparative Example 6 is inferior to that of Example 1 at low hydrogen levels. This may be due to the deterioration of the reversibility of low hydrogen storage and release in the alloy structure of Comparative Example 6 after multiple cycles.

[0100] In summary, the hydrogen storage alloy bed of Example 1 of the present invention undergoes 50 hydrogen absorption and desorption cycles, and the hydrogen desorption amount decays slowly, and the PCT curves are consistent under different numbers of cycles, indicating that its hydrogen absorption and desorption cycle stability is better, and the alloy structure or composition design is more conducive to long-term reversible hydrogen storage and desorption. The hydrogen desorption amount of Comparative Example 6 decays rapidly during the cycle, and the PCT curve is dispersed, indicating that the cyclic stability of the hydrogen storage alloy is poor. After multiple hydrogen absorption and desorption, the hydrogen storage and desorption performance deteriorates more significantly. This may be because the alloy has more serious structural distortion, element segregation and other problems during the cycle, affecting the thermodynamic and kinetic properties of hydrogen desorption. The above is only an embodiment of the present invention, and the common knowledge such as the specific technical solutions and / or characteristics in the solution are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. A low expansion and high stability alloy bed material suitable for large particle size hydrogen storage alloys, characterized by: The raw materials include, by weight: 85-96 parts of hydrogen storage material, 4-5 parts of solder paste, 4-5 parts of organic adhesive, and 1-3 parts of thermal conductive material; the solder paste includes, by weight: 88-90 parts of liquid metal material, 4-8 parts of flux, 2-6 parts of dispersant, 0.1-0.6 parts of activator, and 0.1-0.2 parts of thixotropic agent.

2. The low expansion and high stability alloy bed suitable for large particle size hydrogen storage alloy according to claim 1, characterized in that: The hydrogen storage material is at least one of titanium AB2 type, titanium AB type, rare earth AB3, rare earth AB5 type, vanadium-based solid solution type, and magnesium-based hydrogen storage alloy.

3. The low expansion and high stability alloy bed suitable for large particle size hydrogen storage alloy according to claim 2, characterized in that: The hydrogen storage material is in powder form, and the average particle size of the hydrogen storage material is ≤3.2 mm.

4. The low expansion and high stability alloy bed suitable for large particle size hydrogen storage alloy according to claim 3, characterized in that: The average particle size of the hydrogen storage material is 1-2 mm.

5. The low expansion and high stability alloy bed suitable for large particle size hydrogen storage alloy according to claim 4, characterized in that: The organic adhesive is at least one of epoxy resin, polyurethane, silicone rubber, polyethylene, acrylic acid, and inorganic ceramic adhesive, and the viscosity of the organic adhesive is 4000-6000 cps.

6. The low expansion and high stability alloy bed suitable for large particle size hydrogen storage alloy according to claim 5, characterized in that: The thermally conductive material is a metal thermally conductive material or a carbon-based thermally conductive material, including at least one of aluminum powder, copper powder, graphene, graphite carbon powder, expanded graphite, flake graphite, and acetylene black.

7. The low expansion and high stability alloy bed suitable for large particle size hydrogen storage alloy according to claim 6, characterized in that: The thermal conductive material is flake graphite, and the added amount of the thermal conductive material is 1-3 wt%.

8. The low expansion and high stability alloy bed suitable for large particle size hydrogen storage alloy according to claim 7, characterized in that: The soldering flux is modified rosin; the dispersant is one or more of isopropyl alcohol and diethylene glycol hexyl ether; the activator is one or more of DL-malic acid, succinic acid and adipic acid; and the thixotropic agent is one or more of amide oligomer and sodium lauryl sulfate.

9. The method for preparing a low expansion and high stability alloy bed suitable for large-particle hydrogen storage alloy according to any one of claims 1 to 8, characterized in that: The steps include: Step I: uniformly mixing solder paste and organic adhesive to obtain system I; Step II, adding hydrogen storage material to system I and mixing evenly to obtain system II; Step III, adding thermal conductive material to system II and mixing evenly to obtain system III; Step IV: Place the system III into a mold, press to obtain a block of hydrogen storage bed elements, and solidify to obtain a solid hydrogen storage bed.

10. The method for preparing a low expansion and high stability alloy bed suitable for large-particle hydrogen storage alloy according to claim 9, characterized in that: In step IV, the pressure is 400-650 MPa and maintained for 60 seconds; the curing condition is standing at room temperature for 24 hours.

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