Cold-rolled Mg-Ni-Si hydrogen storage alloy and preparation method thereof

Abstract

The invention relates to a cold-rolled Mg-Ni-Si hydrogen storage alloy and a preparation method thereof, and the cold-rolled Mg-Ni-Si hydrogen storage alloy is prepared through cold rolling deformation and mechanical wet ball milling, and has excellent hydrogen storage performance and good low-temperature dynamic characteristics. Specifically, the alloy contains 5%-25% of Ni, 0.1%-8% of Si and inevitable impurities, and the absorption and desorption rate and the hydrogen storage capacity of hydrogen are mainly improved. The preparation method comprises the following steps: smelting a pure magnesium ingot, an Mg-Ni intermediate alloy and an Mg-Si intermediate alloy under a vacuum condition, and then carrying out cold rolling deformation and wet ball milling treatment. According to the invention, the hydrogen storage performance is improved by utilizing cold rolling deformation and element self-catalysis effect, and experimental results show that the hydrogen storage material can release 6.11 wt.% of hydrogen at 200 DEG C in only 227 minutes, and can quickly absorb 5.70 wt.% of hydrogen within 3 minutes at 180 DEG C, so that the hydrogen storage material has a good application prospect. Through combination of alloying and cold rolling processes, the performance of the magnesium-based hydrogen storage material is remarkably improved, and a new solution is provided for wide application of hydrogen energy.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen energy, and particularly relates to a cold-rolled Mg-Ni-Si hydrogen storage alloy and a preparation method thereof. Background Art

[0002] Hydrogen energy has great potential in reducing environmental pollution and promoting energy transformation due to its abundant resources, no carbon emissions, high energy density (120 MJ / kg), and diverse application scenarios. Therefore, it has become a global development strategy and a focus of competition. However, safe and efficient hydrogen storage and transportation technology is one of the main bottlenecks restricting the development of the hydrogen energy industry chain.

[0003] Among various hydrogen storage technologies, solid-state hydrogen storage technology based on magnesium-based materials has opened up prospects for the large-scale utilization of hydrogen energy due to its advantages such as low cost, high hydrogen storage density (7.6 wt.% and 110 g H2 / L), safety and efficiency, and good reversibility. However, the inherent challenges related to thermodynamics and kinetics in magnesium-based hydrogen storage materials still exist, which directly lead to the disadvantages of high hydrogen absorption and desorption temperatures (>350 °C) and slow reaction rates. Therefore, how to solve these problems remains the main scientific challenge for the wide application of magnesium-based solid-state hydrogen storage technology.

[0004] Currently, common hydrogen storage methods include high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage, and solid material hydrogen storage. The first two hydrogen storage methods are technically mature and have been industrialized, while solid material hydrogen storage is still in the theoretical research stage and lacks a supporting industry, making it difficult to be widely applied in the short term. The high-pressure gaseous hydrogen storage method has a low hydrogen storage density and is suitable for short-distance hydrogen transportation. However, with the increase in hydrogen usage and long-distance transportation, its transportation cost and safety cannot meet the requirements. Low-temperature liquid hydrogen storage requires special ultra-low temperature containers, and hydrogen is prone to volatilization, making it difficult to solve problems such as cost, and it is difficult to commercialize. The solid-state hydrogen storage method has advantages such as high hydrogen storage density, good safety, and low energy consumption, and has good development prospects.

[0005] Alloying is one of the simplest and most efficient ways to improve the hydrogen storage performance of MgH2, and it is also most conducive to achieving the goal of industrialization. Cold rolling can introduce more dislocations or microcracks into the alloy, providing more active sites and diffusion channels for the dissociation and transfer of hydrogen, thus achieving better hydrogen storage performance. However, the high thermodynamic stability and low kinetic performance of magnesium-based hydrogen storage materials are the key factors restricting the development of the industry. For example, Patent CN101003360A discloses a preparation method of a magnesium-based hydrogen storage material. By incompletely hydrogenating pure magnesium powder under a certain hydrogen pressure and temperature, and then performing ball milling and hydrogen desorption and adsorption treatments, the material can be completely converted into magnesium hydride in a short time. This method has a simple preparation process and high material purity, but it does not solve the problem of poor kinetic performance of magnesium-based hydrogen storage materials. Patent CN115140706B discloses a Mg-Ni-Si-based hydrogen storage material. Through the alloying of Ni and Si elements, fine eutectic structures with catalytic effects are formed in the alloy, improving the hydrogen absorption and desorption kinetic performance and thermodynamic performance of magnesium hydride. However, this method does not perform subsequent cold rolling treatment on the alloy, making it difficult to further improve the hydrogen storage performance.

[0006] Therefore, it is necessary to study new magnesium-based hydrogen storage materials to make up for the deficiencies of existing magnesium-based hydrogen storage materials. Summary of the Invention

[0007] To solve the above problems, the present invention proposes a cold-rolled Mg-Ni-Si hydrogen storage alloy and its preparation method, aiming to improve the low-temperature kinetic performance and hydrogen storage capacity of magnesium-based hydrogen storage materials.

[0008] To achieve the above purpose, the present invention provides the following technical solutions:

[0009] A cold-rolled Mg-Ni-Si hydrogen storage alloy, which is a ball-milled powder prepared by successively subjecting a Mg-Ni-Si alloy to cold rolling deformation and mechanical wet ball milling. According to mass percentage, the Mg-Ni-Si alloy contains 5% - 25% Ni, 0.1% - 8% Si, inevitable impurities, and the balance of Mg.

[0010] A preparation method of the cold-rolled Mg-Ni-Si hydrogen storage alloy as described above, comprising the following steps:

[0011] (1) After proportionally preparing pure magnesium ingots, Mg-Ni master alloy, and Mg-Si master alloy, place them in a graphite silicon carbide crucible in a vacuum induction furnace. The Mg-Ni master alloy contains 5% - 50% Ni, and the Mg-Si master alloy contains 5% - 30% Si. Then evacuate the air and fill it with the protective gas argon. By controlling the heating power, raise the temperature to about 800°C within 30 minutes. Observe the inside of the vacuum furnace. After complete melting, hold for 5 minutes, and then pour it into a stainless steel mold. After natural cooling in the furnace for 40 minutes, take out the sample to obtain the Mg-Ni-Si alloy.

[0012] (2) Cut the melted Mg-Ni-Si alloy into cuboid blocks. After grinding the surface to remove the oxide layer, perform rolling deformation at room temperature. The deformation amount each time does not exceed 5%. Obtain the deformed Mg-Ni-Si alloy through multi-pass rolling deformation.

[0013] (3) File the obtained deformed Mg-Ni-Si alloy into filings, and prepare the ball-milled deformed Mg-Ni-Si alloy powder by mechanical wet ball milling under an argon atmosphere.

[0014] First, in step (2), the force direction during the rolling of the Mg-Ni-Si alloy cuboid block is parallel to the direction of its height.

[0015] Furthermore, the length × width × height of the Mg-Ni-Si alloy cuboid block is (50 - 500 mm) × (5 - 30 mm) × (5 - 15 mm).

[0016] Furthermore, in step (3), during the ball milling process, the ball-to-material ratio is 30:1, the ball milling speed is 150 - 280 rpm, the ball milling time is 5 h - 50 h, the ball milling tank is a stainless steel tank, stainless steel grinding balls are used, and the solvent for wet ball milling is n-heptane.

[0017] Preferably, when simultaneously using grinding balls with diameters of 6 mm, 8 mm, and 10 mm during ball milling, the quantity ratio is 1:24:2.

[0018] Preferably, by mass percentage, when the Mg content in the magnesium-based hydrogen storage material is 86.61 wt.%, the Ni content is 11.24 wt.%, and the Si content is 2.15 wt.%, the total deformation amount of rolling deformation is controlled at 5%.

[0019] Preferably, by mass percentage, when the Mg content in the magnesium-based hydrogen storage material is 86.61 wt.%, the Ni content is 11.24 wt.%, and the Si content is 2.15 wt.%, the total deformation amount of rolling deformation is controlled at 10%.

[0020] Preferably, when the Mg content in the magnesium-based hydrogen storage material is 86.61 wt.%, the Ni content is 11.24 wt.%, and the Si content is 2.15 wt.% by mass percentage, the total deformation amount of rolling deformation is 15%.

[0021] Preferably, by mass percentage, the Mg content in the magnesium-based hydrogen storage material is 86.61 wt.%, the Ni content is 11.24 wt.%, and the Si content is 2.15 wt.%, and the total deformation amount of rolling deformation is controlled at 20%.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. The present invention discloses a cold-rolled Mg-Ni-Si hydrogen storage alloy, which improves the hydrogen storage performance by means of cold rolling deformation and the self-catalysis effect of elements. On the one hand, the formed multiple alloy phases can play a synergistic catalytic role. The Mg2Ni phase can promote the dissociation of H2, and the Mg2Ni3Si phase can provide an additional interface channel for the diffusion of hydrogen atoms, and at the same time helps to improve the ball milling effect of the alloy. The two-phase synergistic catalysis improves the hydrogen absorption and desorption kinetic performance. On the other hand, the alloy after cold rolling introduces more crystal defects and microcracks, and it is easier to obtain fine particles during ball milling, providing favorable conditions for the diffusion of hydrogen atoms and promoting low-temperature kinetics. Therefore, the cold-rolled Mg-Ni-Si hydrogen storage alloy has the following advantages:

[0024] (1) It has good activation properties and can be fully activated without activation or by normal hydrogen absorption and desorption three times.

[0025] (2) It increases the hydrogen desorption amount at medium and low temperatures and improves the hydrogen desorption rate. At 200 °C, the cold-rolled Mg-Ni-Si hydrogen storage alloy only needs 227 min to release 6.11 wt.% of hydrogen after hydrogenation.

[0026] (3) It increases the hydrogen absorption rate. The cold-rolled Mg-Ni-Si hydrogen storage alloy can rapidly absorb 5.70 wt.% of hydrogen within 3 min at 180 °C.

[0027] 2. The present invention also discloses a preparation method of a cold-rolled Mg-Ni-Si hydrogen storage alloy. By using a simple and easy-to-control preparation method, pure magnesium ingots, Mg-Ni intermediate alloy and Mg-Si intermediate alloy are mixed and vacuum melted to obtain Mg-Ni-Si alloy. After rolling deformation at room temperature, mechanical wet ball milling is carried out under an argon atmosphere to obtain ball-milled deformed Mg-Ni-Si alloy powder. The process operation is simple and the equipment requirements are mature, reducing the production cost. This feature makes the present invention have good industrial application prospects. Compared with other complex alloy preparation methods, the present invention is more practical and economical.

[0028] 3. The three elements of magnesium, nickel, and silicon used in the present invention are all materials with rich resources and low prices, which can effectively reduce the overall cost of the hydrogen storage material. This advantage makes the present invention more competitive in practical applications and helps to promote the development of the hydrogen energy industry.

[0029] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0031] Figure 1 SEM diagram of the Mg-Ni-Si alloy prepared in Example 1.

[0032] Figure 2 SEM diagram of the deformed Mg-Ni-Si alloy prepared in Example 1.

[0033] Figure 3 SEM diagram of the deformed Mg-Ni-Si alloy powder prepared in Example 1.

[0034] Figure 4 XRD diagram of the deformed Mg-Ni-Si alloy powder prepared in Example 1.

[0035] Figure 5 Programmed temperature hydrogen desorption test of the magnesium-based hydrogen storage material prepared in Example 1.

[0036] Figure 6 Isothermal hydrogen desorption curve of the magnesium-based hydrogen storage material prepared in Example 1.

[0037] Figure 7 Comparison diagram of the isothermal hydrogen desorption curves of the deformed Mg-Ni-Si alloy powder (CR5) and the as-cast Mg-Ni-Si alloy powder (CAST) prepared in Example 1.

[0038] Figure 8 Isothermal hydrogen absorption curve of the magnesium-based hydrogen storage material prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0040] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation on the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0041] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation on the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0042] Example 1

[0043] A cold-rolled Mg-Ni-Si hydrogen storage alloy. The magnesium-based hydrogen storage material is a milled powder prepared by subjecting an Mg-Ni-Si alloy to cold rolling deformation and mechanical wet ball milling in sequence. By mass percentage, the Mg-Ni-Si alloy contains 5% - 25% Ni, 0.1% - 8% Si, inevitable impurities, and the balance of Mg. The specific preparation method of this magnesium-based hydrogen storage material is as follows:

[0044] (1) Preparation of the Mg-Ni-Si alloy: Put 985 g of pure magnesium ingot, 1865 g of Mg-30 wt.% Ni master alloy, and 2150 g of Mg-5 wt.% Si master alloy into a graphite silicon carbide crucible in a vacuum induction furnace, evacuate, and then fill with the protective gas argon. Raise the temperature to about 800 °C within 30 min, keep it molten for 5 min after melting, then pour it into a stainless steel mold, and take out the sample after natural cooling in the furnace for 40 min to obtain the Mg-Ni-Si alloy;

[0045] (2) Preparation of deformed Mg-Ni-Si alloy: The melted Mg-Ni-Si alloy was cut into cuboid blocks with a length of 80 mm, a width of 25 mm, and a height of 10 mm. After grinding the surface to remove the oxide layer, rolling deformation was carried out at room temperature with a deformation amount of 5% to obtain the deformed Mg-Ni-Si alloy (CR5);

[0046] (3) Preparation of deformed Mg-Ni-Si alloy powder: The obtained deformed Mg-Ni-Si alloy was filed into filings, and 15 g was mechanically wet ball-milled for 10 h under an argon atmosphere to prepare the as-milled deformed Mg-Ni-Si alloy powder (where the ball-to-material ratio was 30:1, the ball-milling speed was 280 rpm, the ball-milling tank was a 500 mL stainless steel tank, stainless steel grinding balls with diameters of 6 mm, 8 mm, and 10 mm were used, and the solvent for wet ball-milling was n-heptane).

[0047] Figure 1 SEM image of the Mg-Ni-Si alloy prepared in Example 1.

[0048] Figure 2 SEM image of the deformed Mg-Ni-Si alloy prepared in Example 1. It can be seen from Figure 2 that compared with the Mg-Ni-Si alloy, more microcracks appeared in the second phase precipitated in the deformed Mg-Ni-Si alloy after cold rolling in Example 1.

[0049] Figure 3 SEM image of the deformed Mg-Ni-Si alloy powder prepared in Example 1. It can be seen from Figure 3 that the particle size of the deformed Mg-Ni-Si alloy powder obtained by cold rolling in Example 1 was uniform, about 11 - 23 μm.

[0050] Figure 4 XRD pattern of the deformed Mg-Ni-Si alloy powder prepared in Example 1. It can be seen from Figure 2 that the deformed Mg-Ni-Si alloy powder was mainly composed of Mg phase, Mg2Ni phase, and Mg2Ni3Si phase.

[0051] The hydrogen storage performance of the deformed Mg-Ni-Si alloy powder prepared in Example 1 was studied as follows:

[0052] Weigh 200 mg of the magnesium-based hydrogen storage material (deformed Mg-Ni-Si alloy powder) prepared in Example 1 in a glove box, and use a high-pressure gas sorption instrument of the PCTpro model to test the hydrogen desorption curve of the sample with temperature: isothermal hydrogen desorption curves at 180 °C, 200 °C, 225 °C, 250 °C, 275 °C and 300 °C under an initial hydrogen pressure of 0.01 MPa; isothermal hydrogen absorption curves at 125 °C, 180 °C, 200 °C and 225 °C under an initial hydrogen pressure of 4 MPa.

[0053] Figure 5 This is the temperature-programmed hydrogen desorption test of the magnesium-based hydrogen storage material (deformed Mg-Ni-Si alloy powder) prepared in Example 1. From Figure 5 it can be seen that the magnesium-based hydrogen storage material (deformed Mg-Ni-Si alloy powder) prepared in Example 1 starts to desorb hydrogen at 168.7 °C.

[0054] Figure 6 This is the isothermal hydrogen desorption curve of the magnesium-based hydrogen storage material (deformed Mg-Ni-Si alloy powder) prepared in Example 1. From Figure 6 it can be seen that the magnesium-based hydrogen storage material (deformed Mg-Ni-Si alloy powder) prepared in Example 1 can release 5.53 wt.% of hydrogen in 10 min at 275 °C; at 250 °C, it only takes 25 min to release 5.82 wt.% of hydrogen.

[0055] Figure 7 This is a comparison chart of the isothermal hydrogen desorption curves of the deformed Mg-Ni-Si alloy powder (CR5 in the figure) and the as-cast Mg-Ni-Si alloy powder (not rolled and deformed, CAST in the figure) prepared in Example 1. From Figure 7 it can be seen that the magnesium-based hydrogen storage material (deformed Mg-Ni-Si alloy powder) prepared in Example 1 can release 6.11 wt.% of hydrogen in 227 min at 200 °C; at 180 °C, it only takes 700 min to release 5.25 wt.% of hydrogen. Compared with the as-cast Mg-Ni-Si alloy powder without cold rolling deformation, not only is the hydrogen desorption rate significantly increased, but also the hydrogen desorption amount is significantly increased. The magnesium-based hydrogen storage material (deformed Mg-Ni-Si alloy powder) prepared in Example 1 not only has a lower initial hydrogen desorption temperature, but also the hydrogen desorption kinetics is significantly improved.

[0056] Figure 8 This is the isothermal hydrogen absorption curve of the magnesium-based hydrogen storage material prepared in Example 1. From Figure 8 it can be seen that the magnesium-based hydrogen storage material prepared in Example 1 can rapidly absorb 5.70 wt.% of hydrogen within 3 min at 180 °C, and can even absorb 5.06 wt.% of hydrogen within 60 min at 125 °C. The hydrogen absorption kinetics of the magnesium-based hydrogen storage material prepared in Example 1 is significantly improved.

[0057] Example 2

[0058] The difference between this example and Example 1 is that in step (2) of Example 1, “rolling deformation is carried out at room temperature with a deformation amount of 5% to obtain a deformed Mg-Ni-Si alloy” is modified to “rolling deformation is carried out at room temperature with a deformation amount of 5% per pass and rolling for 2 passes to obtain a deformed Mg-Ni-Si alloy”. The remaining preparation conditions are the same as those in Example 1, thereby obtaining milled deformed Mg-Ni-Si alloy powder (CR10 alloy powder).

[0059] Example 3

[0060] The difference between this example and Example 1 is that in step (2) of Example 1, “rolling deformation is carried out at room temperature with a deformation amount of 5% to obtain a deformed Mg-Ni-Si alloy” is modified to “rolling deformation is carried out at room temperature with a deformation amount of 5% per pass and rolling for 3 passes to obtain a deformed Mg-Ni-Si alloy”. The remaining preparation conditions are the same as those in Example 1, thereby obtaining milled deformed Mg-Ni-Si alloy powder (CR15 alloy powder).

[0061] Example 4

[0062] The difference between this example and Example 1 is that in step (2) of Example 1, “rolling deformation is carried out at room temperature with a deformation amount of 5% to obtain a deformed Mg-Ni-Si alloy” is modified to “rolling deformation is carried out at room temperature with a deformation amount of 5% per pass and rolling for 4 passes to obtain a deformed Mg-Ni-Si alloy”. The remaining preparation conditions are the same as those in Example 1, thereby obtaining milled deformed Mg-Ni-Si alloy powder (CR20 alloy powder).

[0063] It can be seen from the above examples that the cold-rolled Mg-Ni-Si hydrogen storage alloy in the present invention has the following advantages:

[0064] (1) It has good activation properties and can be fully activated without activation or by normal hydrogen absorption and desorption three times.

[0065] (2) The mid-low temperature hydrogen desorption amount is increased and the hydrogen desorption rate is improved (at 200 °C, the cold-rolled Mg-Ni-Si hydrogen storage alloy only needs 227 min to release 6.11 wt.% of hydrogen after hydrogenation).

[0066] (3) The hydrogen absorption rate is increased (the cold-rolled Mg-Ni-Si hydrogen storage alloy can rapidly absorb 5.70 wt.% of hydrogen within 3 min at 180 °C).

[0067] Table 1 is a performance comparison table of the hydrogen absorption amount at 300 °C for 5 min, the hydrogen desorption amount at 225 °C for 10 min, and the hydrogen desorption amount at 200 °C for 200 min of the ball-milled deformed Mg-Ni-Si alloy powders prepared in Examples 1 to 4.

[0068] Table 1 Comparison results of the properties of the ball-milled deformed Mg-Ni-Si alloy powders with different deformation amounts in the examples

[0069]

[0070] It can be seen from Table 1 that compared with the alloy without cold rolling deformation, the hydrogen desorption amount at 225 °C for 10 min and the hydrogen desorption amount at 200 °C for 200 min in Example 1 of the present invention have a significant improvement effect. This shows that performing a certain degree of cold rolling deformation on the Mg-Ni-Si alloy can significantly improve the hydrogen absorption and desorption performance of the alloy near 200 °C.

[0071] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A cold-rolled Mg-Ni-Si hydrogen storage alloy, characterized in that: The magnesium-based hydrogen storage material is a ball-milled powder prepared by sequentially cold-rolling deformation and mechanical wet ball milling of a Mg-Ni-Si alloy. Calculated by mass percentage, the Mg-Ni-Si alloy contains 5% to 25% Ni, 0.1% to 8% Si, unavoidable impurities and the remainder Mg.

2. A method for preparing the cold-rolled Mg-Ni-Si hydrogen storage alloy as claimed in claim 1, characterized in that: The steps include: (1) A pure magnesium ingot, a Mg-Ni master alloy and a Mg-Si master alloy are mixed in proportion and placed in a graphite silicon carbide crucible in a vacuum induction furnace, wherein the Mg-Ni master alloy contains 5% to 50% Ni and the Mg-Si master alloy contains 5% to 30% Si; then the furnace is evacuated and filled with argon as a protective gas; the temperature is raised to about 800° C. within 30 minutes by controlling the heating power, and the vacuum furnace is observed. After the furnace is completely melted, the temperature is kept for 5 minutes, and then the mixture is poured into a stainless steel mold. After the mixture is naturally cooled in the furnace for 40 minutes, the sample is taken out to obtain a Mg-Ni-Si alloy; (2) cutting the smelted Mg-Ni-Si alloy into rectangular blocks, grinding the surface to remove the oxide layer, and then rolling and deforming at room temperature, with the deformation amount of each time not exceeding 5%, and obtaining a deformed Mg-Ni-Si alloy through multiple rolling deformations; (3) The obtained deformed Mg-Ni-Si alloy is filed into filings, and mechanical wet ball milling is performed under an argon atmosphere to prepare ball-milled deformed Mg-Ni-Si alloy powder.

3. The method for preparing the cold-rolled Mg-Ni-Si hydrogen storage alloy according to claim 2, characterized in that: In step (2), the force direction of the Mg-Ni-Si alloy rectangular block during rolling is parallel to the direction of its height.

4. The method for preparing the cold-rolled Mg-Ni-Si hydrogen storage alloy according to claim 3, characterized in that: The length×width×height of the Mg-Ni-Si alloy rectangular block is (50-500 mm)×(5-30 mm)×(5-15 mm).

5. The method for preparing the cold-rolled Mg-Ni-Si hydrogen storage alloy according to claim 2, characterized in that: In step (3), the ball-to-material ratio during ball milling is 30:1, the ball milling speed is 150-280 rpm, the ball milling time is 5 h-50 h, the ball milling tank is a stainless steel tank, stainless steel grinding balls are used, and the solvent for wet ball milling is n-heptane.

6. The method for preparing the cold-rolled Mg-Ni-Si hydrogen storage alloy according to claim 5, characterized in that: During ball milling, grinding balls with diameters of 6 mm, 8 mm and 10 mm are used at the same time, and the ratio of their quantity is 1:24:

2.

7. The method for preparing the cold-rolled Mg-Ni-Si hydrogen storage alloy according to claim 2, characterized in that: In terms of mass percentage, the Mg content in the magnesium-based hydrogen storage material is 86.61wt.%, the Ni content is 11.24wt.%, and the Si content is 2.15wt.%, and the total deformation amount of rolling deformation is controlled at 5%.

8. The method for preparing the cold-rolled Mg-Ni-Si hydrogen storage alloy according to claim 2, characterized in that: In terms of mass percentage, the Mg content in the magnesium-based hydrogen storage material is 86.61wt.%, the Ni content is 11.24wt.%, and the Si content is 2.15wt.%, and the total deformation amount of rolling deformation is controlled at 10%.

9. The method for preparing the cold-rolled Mg-Ni-Si hydrogen storage alloy according to claim 2, characterized in that: When, by mass percentage, the Mg content in the magnesium-based hydrogen storage material is 86.61wt.%, the Ni content is 11.24wt.%, and the Si content is 2.15wt.%, the total deformation amount of the rolling deformation is controlled at 15%.

10. The method for preparing the cold-rolled Mg-Ni-Si hydrogen storage alloy according to claim 2, characterized in that: In terms of mass percentage, the Mg content in the magnesium-based hydrogen storage material is 86.61wt.%, the Ni content is 11.24wt.%, and the Si content is 2.15wt.%, and the total deformation amount of rolling deformation is controlled at 20%.

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