An easily activated Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy and a preparation method thereof

Abstract

The application relates to an easily-activated Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy and a preparation method thereof, and belongs to the technical field of hydrogen storage alloy materials. At least one of the problems in the prior art, such as high activation difficulty, long activation period, poor hydrogen absorption and desorption kinetic performance and the like of a Ti-Fe-based hydrogen storage alloy, is solved. The application provides an easily-activated Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy, and the chemical formula of the hydrogen storage alloy is Ti 1.15 Fe 0.8 Y 0.03 Mn 0.35‑x‑y‑ z Zr x Co y Zn z , wherein x, y and z are atomic ratios, and 0.05<=x<=0.15, 0.02<=y<=0.1 and 0.02<=z<=0.1. The Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy provided by the application has good activation performance and hydrogen absorption and desorption performance through component design and preparation process improvement, and can be activated at one time under the condition of 30 DEG C and 3 MPa, the hydrogen storage capacity is greater than or equal to 1.69 wt.%, the hydrogen absorption plateau pressure is greater than or equal to 0.39 MPa, and the hydrogen desorption plateau pressure is greater than or equal to 0.3 MPa.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogen storage alloy materials, and particularly relates to an easily activated Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy and a preparation method thereof. BACKGROUND

[0002] TiFe intermetallic compound can store a large amount of hydrogen (about 1.9wt.%H2) at room temperature and relatively low pressure. High-density TiFe hydride has been applied in many fields. This AB-type compound usually needs an activation procedure to absorb hydrogen for the first time, especially when it is produced by melting (induction furnace or arc furnace). Generally, this activation process includes a slow and complex heat treatment cycle, high-temperature and cooling alternating heating, high-pressure hydrogen in high vacuum.

[0003] The modification methods of TiFe alloy include alloying part of Fe or Ti with one or several elements, chemical surface modification, mechanical alloying, etc. Studies have shown that mechanically alloyed TiFe can be simply activated, however, due to the appearance of amorphous phase, the hydrogen storage capacity is poor; surface modification can promote the hydrogenation of the material by catalyzing the dissociative chemisorption of hydrogen molecules with a certain transition metal or alloy deposited on the surface, or eliminating the stable oxide layer with acid or alkali, which also helps to improve the resistance to poisoning of TiFe alloy. Among these methods, element substitution method is considered to be the most feasible, and a large number of studies have been carried out. When Fe is partially replaced by Ni, Co, Al, V, Pd, Mn or Cr, the activation rate of the alloy is high. In the case of adding Mn, it is found that it is very effective for improving the activation characteristics and increasing the permeation rate to impure gas. However, this substitution will lead to a decrease in plateau pressure and a more inclined plateau region, which is not conducive to the development of hydrogen storage devices and proton exchange membrane fuel cells.

[0004] In addition to the improvement of hydrogen storage material formula, people have also explored the processing method of hydrogen storage alloy. TiFe alloy containing a small amount of Ni is ball milled for 20-30 hours under Ar gas protection, and the hydrogen absorption performance is good, and it is easy to activate even without activation. However, the ball milling time is too long, which is not conducive to large-scale production; and some researchers have observed that the yield loss is as high as 40% after ball milling for 40 hours. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide an easily activated Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy and a preparation method thereof, so as to solve at least one of the problems in the prior art, such as high activation difficulty, long activation period, poor hydrogen absorption and desorption kinetic performance (especially the defects of platform decline and inclination) of Ti-Fe-based hydrogen storage alloy.

[0006] The application provides an easy-activated Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy, and the chemical formula of the hydrogen storage alloy is Ti 1.15 Fe 0.8 Y 0.03 Mn 0.35-x-y-z Zr x Co y Zn z , wherein x, y and z are atomic ratios, and 0.05 <= x <= 0.15, 0.02 <= y <= 0.1, and 0.02 <= z <= 0.1.

[0007] Preferably, the application is characterized in that x:y:z = 0.1:0.05:0.05.

[0008] Specifically, the hydrogen storage alloy comprises a multi-phase structure, and contains a TiFe phase and an intermetallic compound ZrMn2 phase, and the proportion of the ZrMn2 phase is 10-15% of the TiFe phase.

[0009] Specifically, Y exists in a free state, and Co and Zn are solid-solved in the TiFe phase.

[0010] Specifically, the hydrogen storage alloy has a nanocrystalline structure, and the average grain size is 15-35 nm.

[0011] The application further discloses a preparation method of the hydrogen storage alloy, which comprises the following specific steps.

[0012] S1: ingredients are prepared according to a preset chemical formula, wherein the loss on ignition of Mn, Zn and rare earth Y is increased by a certain proportion when the ingredients are weighed;

[0013] S2: the prepared raw materials are sequentially placed in a zirconia crucible, a pure iron rod is vertically placed along the crucible wall, a block-shaped rare earth Y is placed at the bottom of the crucible, sponge Ti and Zr are placed above the rare earth, and electrolytic Mn, Co and Zn are placed above the sponge Ti and Zr;

[0014] S3: after the materials are sequentially placed, the furnace cover is covered, vacuum is drawn, pure argon gas is filled as a protective gas, and heating is performed to obtain a molten liquid master alloy, the liquid alloy is kept in a molten state, and the liquid alloy is poured into a copper casting mold to obtain a master alloy ingot;

[0015] S4: after the master alloy ingot is mechanically broken and sieved, the sieved alloy powder and stainless steel grinding balls are loaded into a stainless steel ball mill tank, high-purity argon gas is filled after vacuum is drawn, and the ball-milled alloy powder, i.e., the hydrogen storage alloy, is obtained after the ball milling in a full-planet high-energy ball mill.

[0016] Specifically, the loss on ignition of the Mn, Zn and rare earth Y in the step S1 is 5%-10%.

[0017] Specifically, the specific process and parameters of step S3 are as follows:

[0018] After covering the furnace cover, vacuumize to 1x10 -2 ~ 5x10 -5 Pa, fill pure argon to 0.01~0.1MPa, melting temperature 1500~1650℃, melting holding time 3~10 minutes, preferably 5~8 minutes.

[0019] Specifically, the screening operation in step S4 uses a 200-mesh sieve, and the undersize alloy powder has a diameter of ≤75μm.

[0020] Specifically, the specific parameters of the ball milling operation in step S4 are as follows: ball-to-material ratio 1:15~25, rotation speed 300~500rpm, ball milling time 0.5~2.0 hours; preferably ball-to-material ratio 1:20, rotation speed 350rpm, ball milling time 40min.

[0021] The Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy provided by the application has good activation performance and hydrogen absorption and desorption performance through component design and preparation process improvement, and can complete activation at one time under the condition of 30℃ and 3MPa, has a hydrogen storage capacity of ≥1.69wt.%, a hydrogen absorption plateau pressure of ≥0.39MPa, and a hydrogen desorption plateau pressure of ≥0.3MPa.

[0022] Compared with the prior art, the application can at least achieve one of the following beneficial effects:

[0023] 1. The Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy provided by the application is easy to activate, has high hydrogen storage capacity, and has good hydrogen absorption and desorption performance. The application first uses rare earth element Y and transition metals Mn, Co, Zn and Zr for alloying through chemical modification (formula optimization), reduces the activation condition of TiFe alloy, and shortens the activation period; then the as-cast sample is subjected to short-time ball milling, the microstructure is improved, the disadvantages of Ti-Fe-based hydrogen storage alloy are overcome, the advantages are retained, and the comprehensive performance of the new hydrogen storage alloy is significantly improved, which will be described below:

[0024] The application adds Zr and Mn elements to the Ti-Fe alloy, Zr and Mn can form ZrMn2 phase, this intermetallic compound can significantly improve the activation capacity and increase the hydrogen storage capacity; adding a small amount of rare earth Y can significantly improve the activation performance of the alloy while maintaining the hydrogen absorption capacity, and significantly shorten the incubation time during alloy activation; the addition of Co and Zn can increase the unit cell volume of the alloy, which can not only improve the activation performance of the alloy, but also maintain the hydrogen storage capacity of the alloy; and the addition of Zn can significantly improve the corrosion resistance of the alloy, and can improve the activation performance and cycle stability of the alloy.

[0025] The present application maximizes the activation performance of the alloy through the synergistic effect of the alloy activation performance of different elements.

[0026] 2. The present application further improves the performance of the hydrogen storage alloy through the improvement of the microstructure. Short-time ball milling of the as-cast sample improves the microstructure, overcomes the drawbacks of the Ti-Fe-based hydrogen storage alloy, does not cause a large amount of agglomeration, and retains the advantages thereof; mechanical ball milling significantly reduces the grain size of the alloy and forms a large number of crystal defects, increases the nucleation points and diffusion channels of hydrogen, further reduces the thermal stability of the hydride, and improves the hydrogen absorption and desorption kinetics of the alloy.

[0027] 3. The hydrogen storage alloy provided by the present application can be activated once under the condition of 30℃ and hydrogen pressure of 3MPa, has a hydrogen storage capacity of ≥1.69wt.%, a hydrogen absorption plateau pressure of ≥0.39MPa, and a hydrogen desorption plateau pressure of ≥0.3MPa.

[0028] 4. The hydrogen storage alloy provided by the present application is prepared by using raw materials that are easy to obtain, common equipment, and relatively mild process conditions, is easy to operate, has a relatively short time consumption, and is suitable for large-scale manufacturing and wide promotion.

[0029] The above technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification or be understood through the implementation of the present application. The purposes and other advantages of the present application can be achieved and obtained from the contents specifically indicated in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings are included to provide a further understanding of the embodiments, and are incorporated in and constitute a part of this specification, illustrate embodiments of the application, and together with the description serve to explain the principles of the application. In the drawings:

[0031] Figure 1 XRD diffraction spectrum of the as-cast alloy in Examples 1-6;

[0032] Figure 2 SEM morphology of the ball-milled alloy powder in Examples 1-6;

[0033] Figure 3 XRD spectrum of the ball-milled alloy powder in Examples 1-6;

[0034] Figure 4 HRTEM morphology of the ball-milled alloy in Examples 1-6 (red dashed line is the position of lattice defects). DETAILED DESCRIPTION

[0035] The preferred embodiments of the present application will be described in detail below with reference to the drawings, in which the figures constitute a part of the present application and are used to explain the principles of the embodiments of the present application, but are not used to limit the scope of the present application.

[0036] The present application provides an easily-activated Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy, the chemical formula of the hydrogen storage alloy is Ti 1.15 Fe 0.8 Y 0.03 Mn 0.35-x-y-z Zr x Co y Zn z , wherein x, y, and z are atomic ratios, and 0.05≤x≤0.15, 0.02≤y≤0.1, and 0.02≤z≤0.1.

[0037] The roles and content determination of the above components are as follows:

[0038] Ti and Fe: Ti and Fe are main components in the alloy, the generated TiFe phase is the main phase for hydrogen absorption and desorption reaction, and if the proportion is too low, the hydrogen storage capacity of the alloy will be reduced.

[0039] Y: A small amount of rare earth Y can significantly improve the activation performance of the alloy while maintaining the hydrogen absorption capacity, and significantly shorten the incubation time during activation of the alloy, because rare earth elements are easy to form rare earth hydride with hydrogen atoms, and become the catalytic active center of the alloy. The optimal value range of Y atomic ratio is 3-4% of Fe atomic ratio, and excessive Y will reduce the hydrogen storage capacity of the alloy.

[0040] Zr and Mn: ZrMn2 generated can participate in hydrogen absorption and desorption reaction, improve the activation performance of the alloy, and slightly improve the hydrogen storage capacity of the alloy, but excessive ZrMn2 phase will reduce the stability of the hydrogen absorption and desorption platform pressure of the alloy, which is not conducive to the application of the alloy.

[0041] Co and Zn: The addition of Co and Zn can increase the unit cell volume of the alloy, which not only can improve the activation performance of the alloy, but also can maintain the hydrogen storage capacity of the alloy. The optimal content of Co and Zn is about 1 / 2 of Zr, if the addition amount is too small, the expansion effect of the unit cell volume of the alloy will be reduced, which is not conducive to improving the activation performance, and if the addition amount is too much, the hydrogen storage capacity of the alloy will be greatly reduced.

[0042] Zn: Zn can improve the corrosion resistance of the alloy, thereby improving the cycle stability of the alloy, and the addition of Zn can also improve the defect density of the alloy, thereby slightly improving the activation performance of the alloy, but excessive Zn will reduce the hydrogen storage capacity of the alloy.

[0043] From the role of these elements, it can be seen that the TiFe phase is the main phase of the alloy participating in the hydrogen absorption and desorption reaction, the addition of other elements can improve the activation performance of the alloy, but there are also certain adverse effects, such as Y, Co, Zn can reduce the hydrogen storage capacity of the alloy, Zr, Mn can reduce the stability of the hydrogen absorption and desorption platform pressure. Therefore, in order to ensure the hydrogen storage capacity and the stability of the platform pressure of the alloy, the addition amount of each element must be strictly controlled. Through many experiments, it is found that Ti 1.15 Fe 0.8 Y 0.03 Mn 0.35-x-y-z Zr x Co y Zn z The optimal selection of x:y:z is x:y:z=0.1:0.05:0.05.

[0044] Preferably, characterized in that x:y:z=0.1:0.05:0.05.

[0045] Specifically, the hydrogen storage alloy includes a multi-phase structure, contains a TiFe phase and an intermetallic compound ZrMn2 phase, and the proportion of the ZrMn2 phase is 10-15% of the TiFe phase (such as Figure 1 Excessive ZrMn2 phase will reduce the stability of the hydrogen absorption and desorption platform pressure of the alloy, which is not conducive to the application of the alloy.

[0046] Specifically, Y exists in a free state, and Co and Zn are solid-solved in the matrix phase (TiFe phase). The free Y can fully exert its catalytic effect to improve the activation performance of the alloy, and the solid-solution of Co and Zn in the TiFe phase is beneficial to increase the unit cell volume of the alloy and improve the activation performance.

[0047] Specifically, the hydrogen storage alloy has a nanocrystalline structure, and the average grain size is 15-35nm. The small grain size combined with a large number of crystal defects (the red dashed line in the figure is the position of the crystal lattice defect) helps to reduce the thermal stability of the hydride and improve the hydrogen absorption and desorption kinetic performance of the alloy. Figure 4

[0048] The Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy provided by the application has good activation performance and hydrogen absorption and desorption performance through component design and preparation process improvement, and can complete activation at one time under the condition of 30 DEG C and 3MPa, the hydrogen storage capacity is ≥1.69wt.%, the hydrogen absorption platform pressure is ≥0.39MPa, and the hydrogen desorption platform pressure is ≥0.3MPa.

[0049] The application also discloses a preparation method of the hydrogen storage alloy.

[0050] ​S1: ingredients are prepared according to a preset chemical formula, wherein the Mn, Zn and rare earth Y are weighed with a certain proportion of loss on ignition;

[0051] S2: the prepared raw materials are sequentially placed in a zirconia crucible, a pure iron rod is vertically placed along the crucible wall, the block-shaped rare earth Y is placed at the bottom of the crucible, the sponge Ti and Zr are placed above the rare earth, and the electrolytic Mn, Co and Zn are placed above the sponge Ti and Zr;

[0052] S3: after the materials are sequentially placed in order, the furnace cover is covered, vacuum is drawn, pure argon gas is filled as a protective gas, and heating is performed to obtain a molten liquid master alloy, the liquid alloy is poured into a copper mold to obtain a master alloy ingot;

[0053] S4: the master alloy ingot is mechanically crushed and sieved, the undersize alloy powder is loaded into a stainless steel ball mill tank together with stainless steel grinding balls, high-purity argon gas is filled after vacuumizing, and the alloy powder in a ball-milled state, i.e. the hydrogen storage alloy, is obtained after ball milling in a full-planet high-energy ball mill.

[0054] Scientific component design combined with appropriate ball milling process can obtain alloy powder with special structure, thereby making the alloy have excellent activation performance.

[0055] Specifically, the loss on ignition of the Mn, Zn and rare earth Y in step S1 is 5% to 10%, and the Mn and Zn and the rare earth Y are easy to volatilize, so a certain loss on ignition needs to be added during the process of ingredient preparation and heating and melting, generally 5 to 8%, and at most not more than 10%.

[0056] Specifically, the mass purity of each raw material metal is ≥99.5%.

[0057] Specifically, the specific process and parameters of step S3 are as follows:

[0058] After the furnace cover is covered, vacuum is drawn to 1×10 -2 ~ 5×10 -5 Pa, pure argon gas is filled to 0.01 to 0.1 MPa, the melting temperature is 1500 to 1650℃, the melting and holding time is 3 to 10 minutes, the holding time is preferably 5 to 8 minutes, for example, 5, 5.5, 6, 6.5, 7, 7.5, 8 minutes, to ensure that each component is fully melted and uniformly mixed.

[0059] In the above preparation method, mechanical ball milling is one of the key steps, which greatly reduces the grain size of the alloy, and at the same time greatly increases the defect density of the alloy, which provides a channel for the rapid diffusion of hydrogen atoms in the alloy, thereby significantly improving the activation performance and the hydrogen absorption / desorption kinetics of the alloy.

[0060] Specifically, the sieving operation in step S4 uses a 200-mesh sieve, and the undersize alloy powder has a diameter of ≤75 μm. Preparing alloy particles of this particle size neither greatly increases the cost nor prepares for subsequent ball milling.

[0061] Specifically, the ball milling operation in step S4 has the following parameters: a ball-to-material ratio of 1:15-25, a rotation speed of 300-500 rpm, for example, 300, 320, 350, 380, 400, 430, 470, 500 rpm, a ball milling time of 0.5-2.0 hours, for example, 0.5, 1, 1.5, 2 hours; preferably, the ball-to-material ratio is 1:20, the rotation speed is 350 rpm, and the ball milling time is 40 min. Under these ball milling parameters, the generation of excessive amorphous phase in ball milling can be prevented, the hydrogen storage performance of the alloy is not damaged, the size of the alloy particles and grains can be sufficiently reduced, the average grain size is maintained at 15-35 nm, and the activation performance and hydrogen absorption and desorption rate of the alloy are improved.

[0062] The present application forms various intermetallic compounds by adding a small amount of rare earth element Y and transition metals Mn, Zr, Co and Zn, significantly increases the activation performance of the alloy, combines mechanical ball milling to significantly reduce the grain size of the alloy, and forms a large number of crystal defects, increases the nucleation points and diffusion channels of hydrogen, further reduces the thermal stability of the alloy and improves its hydrogen absorption and desorption kinetics, and obtains a hydrogen storage material with excellent hydrogen absorption and desorption kinetics. The alloy prepared by combining the alloy composition design (composition optimization) and the ball milling process (microstructure modification) of the present application has excellent activation performance, and fully meets the requirements of the activation performance of the alloy in actual application.

[0063] The chemical composition and proportion of the specific embodiments of the present application are selected as follows:

[0064] Example 1: Ti 1.15 Fe 0.8 Y 0.03 Mn 0.15 Zr 0.1 Co 0.05 Zn 0.05

[0065] Example 2: Ti 1.15 Fe 0.8 Y 0.03 Mn 0.2 Zr 0.05 Co 0.05 Zn 0.05

[0066] Example 3: Ti 1.15 Fe 0.8 Y 0.03 Mn 0.1 Zr 0.15 Co 0.05 Zn0.05

[0067] Example 4: Ti 1.15 Fe 0.8 Y 0.03 Mn 0.1 Zr 0.1 Co 0.1 Zn 0.05

[0068] Example 5: Ti 1.15 Fe 0.8 Y 0.03 Mn 0.18 Zr 0.1 Co 0.05 Zn 0.02

[0069] Example 6: Ti 1.15 Fe 0.8 Y 0.03 Mn 0.1 Zr 0.1 Co 0.05 Zn 0.1

[0070] Comparative Example 1: Ti 1.1 Fe 0.8 Mn 0.2 (as-cast)

[0071] The rare earth metal Y, sponge Ti and Zr, high purity Fe, electrolytic Mn, Co and Zn are selected according to the chemical formula composition of each example. The high purity iron rod is polished by sandpaper to remove the surface oxide layer, and the rare earth metal Y and electrolytic Mn and Zn are increased by 5-8 wt.% of the burning loss amount during batching. The technical parameters of each stage are as follows: the vacuum induction melting furnace is vacuumized to 1 x 10 -2 -5 x 10 -5 Pa before heating; then 0.01-0.1 MPa of inert gas argon is filled into the furnace as protective gas; the temperature during induction heating is 1500-1650°C; the liquid alloy is kept in the molten state for 3-10 minutes; the ingot alloy is mechanically broken and passed through a 200 mesh sieve, and the particle size is about 75 μm. The alloy powder is loaded into a stainless steel ball mill tank together with stainless steel grinding balls, and is ball milled by a full-coverage planetary ball mill for 0.5-2 hours. All the process parameters can be appropriately selected within the above-mentioned range to prepare the hydrogen storage alloy powder described in the patent.

[0072] Therefore, although only one typical example is given in the present application, the example is applicable to different parameter preparation methods. It is worth emphasizing that all the process parameters can be appropriately selected within the above-mentioned range to prepare the hydrogen storage alloy powder described in the present application.

[0073] Examples 1-6

[0074] Process parameters of Example 1: Ti 1.15 Fe 0.8 Y 0.03 Mn 0.15 Zr 0.1 Co 0.05 Zn 0.05 The bulk rare earth metal Y, sponge Ti and Zr, pure Fe, electrolytic Mn, Co and Zn were selected. The purity of these metals was 99.5%, and they were weighed according to the chemical dosage ratio, wherein the sponge Ti was 437.0 g, the sponge Zr was 72.4 g, the pure Fe was 354.78 g, the rare earth Y was 22.2 g, the electrolytic Mn was 68.7 g, the electrolytic Co was 23.4 g, and the metal Zn was 27.3 g. The weighed bulk metals were placed in a zirconia crucible of a medium-frequency induction furnace according to the designed process, the pure Fe rod was placed vertically along the crucible wall, the bulk rare earth Y was placed at the bottom of the crucible, the sponge Ti and Zr were placed above the rare earth Y, and the electrolytic Mn, Co and Zn were placed above the sponge Ti and Zr. Then the furnace cover was covered, vacuum was extracted for about 30 minutes until the vacuum degree was 5x10 -2 Pa, high-purity argon protection gas was filled again until the gas pressure reached -0.04 MPa, the heating temperature was adjusted to about 1650°C, all the raw material metals were completely melted, the molten liquid metal was kept for 5 minutes to make it uniform, and then the uniformly mixed liquid metal was injected into a cylindrical copper mold with a diameter of 30 mm and a depth of 80 mm. After cooling to room temperature in the furnace, it was taken out to obtain a master alloy ingot.

[0075] The alloy Ti 1.15 Fe 0.8 Y 0.03 Mn 0.15 Zr 0.1 Co 0.05 Zn 0.05 After the ingot was mechanically broken and passed through a 200-mesh sieve, 20 g of sieved alloy powder and 400 g of stainless steel grinding balls were loaded into a stainless steel ball mill tank with a volume of 250 ml, vacuum was extracted and high-purity argon was filled, and then sealed in a full-planet high-energy ball mill for 40 minutes.

[0076] The raw materials of Examples 2-6 and Comparative Examples were weighed according to the chemical formula, and other process parameters were the same as those of Example 1.

[0077] The phase structure of the as-cast and ball-milled powders is tested by XRD, the morphology and microstructure of the ball-milled alloy particles are observed by high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM), and the crystalline state of the alloy is determined by selected-area electron diffraction (SAED). The hydrogen absorption activation performance, hydrogen absorption and desorption capacity and kinetics of the alloy powder are tested by a full-automatic Sieverts device: the hydrogen absorption temperature is 30℃, the initial hydrogen pressure is 3MPa; the hydrogen desorption temperature is 30℃, and the hydrogen desorption is carried out under a pressure of 1×10 -4 MPa.

[0078] Table 1 solid-state hydrogen storage performance of the alloys of different examples (comparative examples)

[0079]

[0080] Figure 1 The XRD patterns of the as-cast alloys of Examples 1-6 are shown in Figure 1. It can be seen that, by adding rare earth Y and Mn, Zr, Co and Zn for alloying, the alloy has a multi-phase structure, in addition to the main phase TiFe, there is also an intermetallic compound ZrMn2 phase, and a free Y phase, while Co and Zn cannot be directly observed in XRD, indicating that Co and Zn have been dissolved in the TiFe phase. Through XRD refinement, it is known that the ZrMn2 phase accounts for 10-15% of the TiFe phase, and the average grain size of the alloy is 15-35 nm.

[0081] Figure 2 The SEM morphologies of the ball-milled alloys of Examples 1-6 are shown in Figure 2. It is observed that, after ball milling, the alloy particles have good dispersity and no obvious agglomeration phenomenon is formed, indicating that the ball milling parameters defined in the present application help to improve the hydrogen absorption and desorption performance.

[0082] Figure 3 The XRD patterns of the ball-milled alloys of Examples 1-6 are shown in Figure 3. It can be found that, after ball milling, the diffraction peaks of the alloy are significantly widened, which is due to the lattice stress and grain refinement after ball milling. Due to the widening of the diffraction peaks, the originally weak Y diffraction peaks are not easy to distinguish.

[0083] Figure 4 The HRTEM morphologies of the ball-milled alloys of Examples 1-6 are shown in Figure 4, which shows that the alloy has a nanocrystalline structure, and the nanocrystalline size is 15-35 nm.

[0084] The above results show that the ball-milled alloy powder has excellent activation performance and high hydrogen storage capacity. Obviously, the alloy preparation process of the application is simple and easy to operate, and is completely suitable for large-scale production, and its performance meets the requirements of hydrogen storage materials for various purposes. Compared with similar alloys at home and abroad, the hydrogen storage performance of the alloy of the application is significantly improved, and has obvious advantages, especially the activation difficulty is greatly reduced, the hydrogen absorption and desorption platform is significantly improved and is more balanced. Under the condition of 30 DEG C and 3 MPa, the activation can be completed at one time, the hydrogen storage capacity is greater than or equal to 1.69 wt.%, the hydrogen absorption platform pressure is greater than or equal to 0.39 MPa, and the hydrogen desorption platform pressure is greater than or equal to 0.3 MPa.

[0085] The above description is only the preferred embodiment of the application, but the protection scope of the application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered in the protection scope of the application.

Claims

1. A method for preparing an easily activated Ti-Fe-Y-Mn-Zr-Co-Zn-based hydrogen storage alloy, characterized in that, The hydrogen storage alloy has the chemical formula Ti. 1.15 Fe 0.8 Y 0.03 Mn 0.15 Zr 0.1 Co 0.05 Zn 0.05 The content of Co and Zn is both 1 / 2 of that of Zr, and the method includes: S1: Prepare the ingredients according to the preset chemical formula, with a certain proportion of burn-off loss added when weighing Mn, Zn and rare earth Y; S2: Place the prepared raw materials in the zirconium oxide crucible in sequence. Place the pure iron rod vertically along the crucible wall, place the blocky rare earth Y at the bottom of the crucible, place the sponge Ti and Zr on top of the rare earth, and place the electrolytic Mn, Co and Zn on top of the sponge Ti and Zr. S3: After the materials are placed in order, the furnace lid is closed, the furnace is evacuated, pure argon is introduced as a protective gas and heated to obtain a molten liquid master alloy. The molten state is kept at a constant temperature, and the liquid alloy is poured into a copper casting mold to obtain a master alloy ingot. S4: After mechanically crushing and sieving the master alloy ingot, the sieved alloy powder and stainless steel grinding balls are loaded into a stainless steel ball mill jar, vacuumed and filled with high-purity argon gas, and ball-milled in an all-round planetary high-energy ball mill to obtain ball-milled alloy powder, namely the hydrogen storage alloy. The specific process and parameters of step S3 are as follows: After closing the furnace lid, evacuate to 1×10⁻⁶. -2 ~5×10 -5 Pa, filled with pure argon gas to 0.01~0.1MPa, melting temperature 1650℃, melting holding time 5min; The specific parameters for the ball milling operation in step S4 are: ball-to-material ratio 1:15-25, rotation speed 300-500 rpm, and ball milling time 40 min; The hydrogen storage alloy has a multiphase structure containing a TiFe phase and an intermetallic compound ZrMn2 phase, with the ZrMn2 phase accounting for 10-15% of the TiFe phase; in the hydrogen storage alloy, Y exists in a free state, while Co and Zn are dissolved in the TiFe phase.

2. The preparation method according to claim 1, characterized in that, The hydrogen storage alloy has a nanocrystalline structure with an average grain size of 15–35 nm.

3. The preparation method according to claim 1, characterized in that, The loss of Mn, Zn and rare earth Y in step S1 is 5% to 10%.

4. The preparation method according to claim 1, characterized in that, In step S4, a 200-mesh sieve is used for sieving, and the diameter of the alloy powder passing through the sieve is ≤75μm.

5. An easily activated Ti-Fe-Y-Mn-Zr-Co-Zn based hydrogen storage alloy, obtained by the preparation method according to any one of claims 1-4, characterized in that, The hydrogen storage alloy has the chemical formula Ti. 1.15 Fe 0.8 Y 0.03 Mn 0.15 Zr 0.1 Co 0.05 Zn 0.05 The content of Co and Zn is half that of Zr.

6. The hydrogen storage alloy according to claim 5, characterized in that, The hydrogen storage alloy has a nanocrystalline structure with an average grain size of 15–35 nm.

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