Magnesium-based composites and methods of forming same

Abstract

The present disclosure provides a magnesium-based composite and a method of forming the same. The method includes performing a casting process on magnesium, at least one first catalytic metal, and at least one first carbon allotrope to form a first magnesium-based solid solution; performing a severe plastic deformation process on the first magnesium-based solid solution to form a second magnesium-based solid solution; and performing a high-energy ball milling process on the second magnesium-based solid solution and the amorphous additive to form the magnesium-based composite material. The magnesium-based composite material comprises a magnesium-based solid solution and an amorphous additive mixed with the magnesium-based solid solution. The magnesium-based solid solution includes magnesium, at least one first catalytic metal, and at least one first carbon allotrope. The amorphous additive includes at least one second catalytic metal and at least one second carbon allotrope. The magnesium-based composite material disclosed by the invention has higher reversible hydrogen storage capacity, higher hydrogen absorption rate and hydrogen desorption rate, lower working temperature and the like. The method is easy to implement, mass production can be carried out, and materials are easy to obtain.

Description

Technical Field

[0001] The present disclosure relates to a magnesium-based composite material and a method for forming the same.

Background Art

[0002] Hydrogen energy is a carbon-free energy source that can avoid the harm of carbon emissions to the climate. More and more applications that rely on fossil fuels have been replaced by hydrogen energy. For example, the number of hydrogen-powered vehicles is increasing. Therefore, finding a suitable hydrogen carrier for storing and releasing hydrogen has become a major issue in the field. However, there is still a lack of hydrogen carriers and methods for forming hydrogen carriers with better hydrogenation and dehydrogenation performance (such as high reversible capacity, rate, etc.). Therefore, there is an urgent need for materials that can be used as better hydrogen carriers and methods for forming them.

Summary of the Invention

[0003] The present disclosure provides a magnesium-based composite material. The magnesium-based composite material includes a magnesium-based solid solution and an amorphous additive mixed with the magnesium-based solid solution. The magnesium-based solid solution includes magnesium, at least one first catalytic metal, and at least one first carbon allotrope. At least one first catalytic metal is selected from the group consisting of aluminum, zinc, zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium, and yttrium. The amorphous additive includes at least one second catalytic metal and at least one second carbon allotrope. At least one second catalytic metal is selected from the group consisting of zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium, and yttrium.

[0004] In some embodiments, the weight percentage of the amorphous additive in the magnesium-based composite material is 1 wt% to 15 wt%.

[0005] In some embodiments, the weight percentage of each at least one first catalytic metal in the magnesium-based solid solution is less than or equal to 9 wt%.

[0006] In some embodiments, when at least one first catalytic metal includes aluminum, the weight percentage of aluminum in the at least one first catalytic metal is the largest.

[0007] In some embodiments, at least one first carbon allotrope and at least one second carbon allotrope are independently selected from the group consisting of graphite, graphene, fullerenes, single-walled carbon nanotubes, multi-walled carbon nanotubes, activated carbon, and carbon black.

[0008] In some embodiments, the weight percentage of at least one first carbon allotrope in the magnesium-based solid solution is less than or equal to 3 wt%.

[0009] In some embodiments, in the amorphous additive, the weight percentage of at least one second carbon allotrope is greater than the weight percentage of at least one second catalytic metal.

[0010] In some embodiments, the average particle size of the magnesium-based composite material is from 20 μm to 80 μm.

[0011] In some embodiments, the average grain size in the magnesium-based solid solution is from 4 μm to 34 μm.

[0012] In some embodiments, the maximum reversible hydrogen storage capacity of the magnesium-based composite material is from 6 wt% to 7 wt%.

[0013] In some embodiments, the hydrogen absorption rate of the magnesium-based composite material is from 2 wt% per minute to 4 wt% per minute, and the hydrogen desorption rate of the magnesium-based composite material is from 0.25 wt% per minute to 1.25 wt% per minute.

[0014] The present disclosure also provides a method of forming a magnesium-based composite material. The method includes the following operations. Casting a magnesium, at least one first catalytic metal, and at least one first carbon allotrope to form a first magnesium-based solid solution, wherein the at least one first catalytic metal is selected from the group consisting of aluminum, zinc, zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium, and yttrium. Performing a severe plastic deformation process on the first magnesium-based solid solution to form a second magnesium-based solid solution. Performing a high-energy ball milling process on the second magnesium-based solid solution and an amorphous additive to form a magnesium-based composite material, wherein the amorphous additive includes at least one second catalytic metal and at least one second carbon allotrope, and the at least one second catalytic metal is selected from the group consisting of zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium, and yttrium.

[0015] In some embodiments, the casting process includes heating the magnesium, at least one first catalytic metal, and at least one first carbon allotrope at a temperature of from 700 °C to 800 °C.

[0016] In some embodiments, the method further includes performing a homogenization process after the casting process and before the severe plastic deformation process, wherein the homogenization process includes heating the first magnesium-based solid solution at a temperature of from 350 °C to 450 °C.

[0017] In some embodiments, the first average grain size in the first magnesium-based solid solution is greater than the second average grain size in the second magnesium-based solid solution, and the second average grain size is from 4 μm to 34 μm.

[0018] In some embodiments, the severe plastic deformation process includes pressing the first magnesium-based solid solution through an angled channel, and the angled channel has a bend angle of from 90° to 120°.

[0019] In some embodiments, the severe plastic deformation process includes repeatedly pressing a first magnesium-based solid solution through an angular channel, and the first magnesium-based solid solution rotates substantially not at all, rotates 90°, or rotates 180° along the long axis of the first magnesium-based solid solution between two consecutive passes through the angular channel.

[0020] In some embodiments, the severe plastic deformation process includes repeatedly pressing a first magnesium-based solid solution through an angular channel, and the number of repetitions is from 4 to 8 times.

[0021] In some embodiments, the high-energy ball milling process is carried out by a high-energy ball mill, and the rotational speed of the high-energy ball mill is from 200 rpm to 500 rpm.

[0022] In some embodiments, the average particle size of the magnesium-based composite material is from 20 μm to 80 μm.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present disclosure can be more fully understood by reading the following detailed description of the embodiments in conjunction with the accompanying drawings. Figure 1 is a flowchart of a method for forming a magnesium-based composite material according to some embodiments of the present disclosure. Figure 2A 、 Figure 2B 、 Figure 2C and Figure 2D are schematic diagrams of a severe plastic deformation process according to some embodiments of the present disclosure. Figure 3A 、 Figure 3B and Figure 3C are optical micrographs of a magnesium-based solid solution after a casting process, a homogenization process, and a severe plastic deformation process, respectively, according to some embodiments of the present disclosure. Figure 4A and Figure 4B are scanning electron micrographs of a magnesium-based composite material during and after a high-energy ball milling process, respectively, according to some embodiments of the present disclosure. Figure 5 is a comparison of X-ray diffraction patterns according to some embodiments of the present disclosure and some comparative embodiments. Figure 6A and Figure 6B is a schematic diagram showing the change of hydrogen absorption and desorption capacity over time according to some embodiments of the present disclosure and some comparative embodiments.

DETAILED DESCRIPTION

[0024] To make the description of the present disclosure more detailed and complete, the following provides a schematic description of various aspects of the embodiments and specific examples of the present disclosure. The present disclosure is not limited to only one form of the embodiments. The embodiments of the present disclosure can be combined or substituted with each other under beneficial circumstances, and other embodiments can be added without further explanation.

[0025] Spatial relative terms, such as above and below, etc., can be used in the present disclosure to describe the relationship between one component or feature in the figure and another component or feature. The spatial relative terms are intended to include different directions of the device during use or operation in addition to the directions described in the figure. For example, the device can be oriented in other directions (such as 90 degrees or other directions). Therefore, the spatial relative terms of the present disclosure can be interpreted correspondingly. In addition, in the present disclosure, unless otherwise specified, the same or similar reference numerals in different figures refer to the same or similar components formed of the same or similar materials by the same or similar methods.

[0026] The terms "about", "substantially", "approximately", "essentially", etc. used in the present disclosure include the numerical value, feature, and the deviation range of the said value and feature that can be understood by those of ordinary skill in the art. For example, considering the error of the value and feature, the foregoing terms can include values within one or more standard deviation ranges (for example, ±5%, ±10%, ±15%, ±20% or ±30% of the said value), or include the deviation of the said feature from the actual operation (for example, "substantially parallel" can mean close to parallel in actual operation, rather than ideally perfectly parallel). In addition, the acceptable deviation range can be selected according to measurement or other characteristics, and there may be more than one deviation applicable to all values and features.

[0027] The present disclosure provides a magnesium-based composite material. The magnesium-based composite material includes a magnesium-based solid solution and an amorphous additive mixed with the magnesium-based solid solution. The magnesium-based solid solution includes magnesium; at least one first catalytic metal selected from the group consisting of aluminum, zinc, zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium, and yttrium; and at least one first carbon allotrope. The amorphous additive includes at least one second catalytic metal selected from the group consisting of zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium, and yttrium; and at least one second carbon allotrope. The magnesium-based composite material of the present disclosure can be used as a hydrogen carrier and has better hydrogenation and dehydrogenation performance, including a higher reversible hydrogen storage capacity (for example, 6 wt% to 7 wt%), a higher hydrogen absorption rate (for example, 2 wt% per minute to 4 wt% per minute), a higher hydrogen desorption rate (for example, 0.25 wt% per minute to 1.25 wt% per minute), a lower working temperature (for example, 300°C to 400°C), etc. Next, the magnesium-based composite material of the present disclosure will be described in detail with the following embodiments.

[0028] The magnesium-based composite material of the present disclosure is a composite material including a magnesium-based solid solution and an amorphous additive. The magnesium-based solid solution and the amorphous additive have distinct characteristics. For example, the magnesium-based solid solution is a solid solution that exists in a solid state and includes magnesium, at least one first catalytic metal, and at least one first carbon allotrope that are uniformly mixed, and the magnesium-based solid solution has a crystal structure. On the other hand, the amorphous additive is amorphous, non-crystalline, and disordered in the atomic-scale structure. The magnesium-based composite material including the magnesium-based solid solution and the amorphous additive mixed together improves the hydrogenation and dehydrogenation performance of the magnesium-based composite material. For example, the hydrogen diffusion path in the magnesium-based composite material can be shortened, and a certain degree of structural defects are included in the magnesium-based composite material to reduce the activation energy of hydrogen dissociation, etc. In some embodiments, the magnesium-based solid solution has a single-crystal structure. In some embodiments, the crystal structure of the magnesium-based solid solution is hexagonal close-packed (HCP). In some embodiments, the average grain size of the crystal structure of the magnesium-based solid solution is 4 μm to 34 μm, such as 4 μm, 9 μm, 14 μm, 19 μm, 24 μm, 29 μm, or 34 μm. The crystal structure defined by the grain size has substantially the same crystal orientation (for example, refer to Figure 3A , Figure 3B and Figure 3C ), so the boundary located between the grains means that the crystal orientation changes. A smaller grain size means more boundaries located between the grains. In the microstructure, the average grain size within the above range provides suitable defects to have a higher hydrogen storage capacity and reduce the activation energy of hydrogen dissociation. In some embodiments, the weight percentage of the preferred magnesium-based solid solution and the weight percentage of the preferred amorphous additive in the magnesium-based composite material are 85 wt% to 99 wt% (such as 85 wt%, 87 wt%, 89 wt%, 91 wt%, 93 wt%, 95 wt%, 97 wt%, or 99 wt%) and 1 wt% to 15 wt% (such as 1 wt%, 3 wt%, 5 wt%, 7 wt%, 9 wt%, 11 wt%, 13 wt%, or 15 wt%), respectively.

[0029] The magnesium-based composite material of the present disclosure is further described in detail according to some embodiments. In some embodiments, the magnesium-based composite material exists in the form of particles to increase the surface area of the magnesium-based composite material. The larger surface area improves the hydrogenation and dehydrogenation performance. For example, when the formation and decomposition of magnesium hydride occur, there can be more magnesium nucleation sites and shorter hydrogen diffusion paths, thereby increasing the hydrogen absorption and desorption rates. In addition, for the magnesium-based composite material with a larger surface area, less deformation can occur during the formation and decomposition of magnesium hydride to reduce the explosion that may occur when heating the magnesium-based composite material. In some embodiments, the average particle size of the magnesium-based composite material with improved hydrogenation and dehydrogenation performance is preferably 20 μm to 80 μm, such as 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 50 μm, 60 μm, 70 μm, or 80 μm.

[0030] The magnesium-based composite material of the present disclosure is further described in detail according to some embodiments. In some embodiments, the maximum reversible (i.e., hydrogen can be reversibly absorbed and desorbed) hydrogen storage capacity of the magnesium-based composite material is 6 wt% to 7 wt%, such as 6.0 wt%, 6.2 wt%, 6.4 wt%, 6.6 wt%, 6.8 wt%, or 7.0 wt%. In some embodiments, the hydrogen absorption rate of the magnesium-based composite material is 2 wt% per minute to 4 wt% per minute, such as 2.0 wt% per minute, 2.5 wt% per minute, 3.0 wt% per minute, 3.5 wt% per minute, or 4.0 wt% per minute. In some embodiments, the hydrogen desorption rate of the magnesium-based composite material is 0.25 wt% per minute to 1.25 wt% per minute, such as 0.25 wt% per minute, 0.50 wt% per minute, 0.75 wt% per minute, 1.00 wt% per minute, or 1.25 wt% per minute. In some embodiments, the maximum reversible hydrogen storage capacity, hydrogen absorption rate, and hydrogen desorption rate are measured at an operating temperature of 300°C to 400°C, such as 300°C, 320°C, 340°C, 360°C, 380°C, or 400°C, and at a hydrogen pressure of 2.5 MPa to 3.5 MPa, such as 2.5 MPa, 2.7 MPa, 2.9 MPa, 3.1 MPa, 3.3 MPa, or 3.5 MPa.

[0031] Next, the magnesium-based solid solution will be described in detail according to some embodiments. The magnesium-based solid solution includes magnesium, at least one first catalytic metal, and at least one first carbon allotrope. Magnesium has a high hydrogen storage capacity, at least one first catalytic metal serves as a catalyst to improve the dissociation of hydrogen from magnesium, and at least one first carbon allotrope provides a larger surface area to increase the kinetic rate of hydrogen absorption and desorption. In some embodiments, the weight percentage of magnesium in the magnesium-based solid solution is preferably greater than or equal to 85 wt%, so as to have a high hydrogen storage capacity and increase the uniformity of the solid solution. In some embodiments, at least one first catalytic metal is preferably selected from the group consisting of aluminum, zinc, zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium, and yttrium. In some embodiments, the weight percentage of each of at least one first catalytic metal in the magnesium-based solid solution is preferably less than or equal to 9 wt%, so as to improve the catalytic effect and increase the uniformity of the solid solution. In some embodiments, at least one first carbon allotrope is preferably selected from the group consisting of graphite, graphene, fullerene, single-walled carbon nanotube, multi-walled carbon nanotube, activated carbon, and carbon black. In some embodiments, the weight percentage of at least one first carbon allotrope in the magnesium-based solid solution is preferably less than or equal to 3 wt%, so as to increase the kinetic rate and increase the uniformity of the solid solution.

[0032] The magnesium-based solid solution of the present disclosure will be further described in detail according to some embodiments. In some embodiments, the weight percentage of aluminum is the highest in at least one first catalytic metal to have better catalytic effects. In some embodiments, the weight percentage of aluminum in the magnesium-based solid solution is preferably 3 wt% to 9 wt%, such as 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt% or 9 wt%. In some embodiments, the weight percentage of zinc in the magnesium-based solid solution is preferably 0.5 wt% to 6 wt%, such as 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt% or 6 wt%. In some embodiments, the weight percentage of zirconium in the magnesium-based solid solution is preferably 0.1 wt% to 1.6 wt%, such as 0.1 wt%, 0.6 wt%, 1.0 wt%, 1.3 wt% or 1.6 wt%. In some embodiments, the weight percentage of each of nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium or yttrium in the magnesium-based solid solution is independently preferably 0.1 wt% to 1 wt%, such as 0.1 wt%, 0.25 wt%, 0.5 wt%, 0.75 wt% or 1 wt%. More specifically, in some embodiments, at least one first catalytic metal includes aluminum, zinc and at least one selected from the group consisting of zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium and yttrium, wherein the weight ratio between aluminum and zinc is preferably 3:1 to 9:1, such as 3:1, 6:1 or 9:1. More specifically, in some embodiments, at least one first catalytic metal includes zinc, zirconium and at least one selected from the group consisting of nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium and yttrium, wherein the weight ratio between zinc and zirconium is preferably 3:1 to 60:1, such as 3:1, 5:1, 10:1, 20:1, 30:1, 40:1, 50:1 or 60:1. When at least one first catalytic metal includes aluminum and zinc, or includes zinc and zirconium, the mechanical properties (e.g., higher tensile strength, higher yield strength, etc.) can be further improved, the corrosion resistance can be increased, and it is beneficial to increase the applicability of the magnesium-based solid solution (e.g., having better welding properties, etc.). In some embodiments, the weight percentage of at least one first carbon allotrope in the magnesium-based solid solution is preferably 1 wt% to 3 wt%, such as 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt% or 3.0 wt%. In some embodiments, at least one first carbon allotrope includes multi-walled carbon nanotubes, and the density of each multi-walled carbon nanotube is preferably 0.01 g / cm 3 to 0.1 g / cm 3 , such as 0.01 g / cm 3 , 0.04 g / cm 3 , 0.06 g / cm 3, 0.08 g / cm 3 or 0.10 g / cm 3 .

[0033] Next, the amorphous additive will be described in detail according to some embodiments. The amorphous additive includes at least one second catalytic metal and at least one second carbon allotrope, wherein at least one second catalytic metal can act as a catalyst for improving the dissociation of hydrogen from magnesium, and at least one second carbon allotrope provides a larger surface area to increase the kinetic rates of hydrogen absorption and desorption. In some embodiments, at least one second catalytic metal is preferably selected from the group consisting of zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium, and yttrium. In some embodiments, the weight percentage of at least one second catalytic metal in the amorphous additive is preferably 35 wt% to 45 wt%, such as 35 wt%, 37 wt%, 40 wt%, 43 wt%, or 45 wt%, to improve the catalytic effect. In some embodiments, at least one second carbon allotrope is preferably selected from the group consisting of graphite, graphene, fullerenes, single-walled carbon nanotubes, multi-walled carbon nanotubes, activated carbon, and carbon black. In some embodiments, the weight percentage of at least one second carbon allotrope in the amorphous additive is preferably 55 wt% to 65 wt%, such as 55 wt%, 57 wt%, 60 wt%, 63 wt%, or 65 wt%, to increase the kinetic rates. In some embodiments, at least one first carbon allotrope and at least one second carbon allotrope are the same. In some embodiments, at least one first carbon allotrope and at least one second carbon allotrope are different. In some embodiments, the weight percentage of at least one second carbon allotrope is greater than the weight percentage of at least one second catalytic metal to facilitate the formation of particulate magnesium-based composites and to create the desired structural defects in the magnesium-based composites (refer to the method for forming magnesium-based composites in detail below). In some embodiments, the weight ratio between at least one second carbon allotrope and at least one second catalytic metal is preferably 1.1:1 to 2.5:1, such as 1.1:1, 1.3:1, 1.5:1, 1.7:1, 1.9:1, 2.1:1, 2.3:1, or 2.5:1.

[0034] The present disclosure also provides a method for forming the above-mentioned magnesium-based composite material. The method includes the following operations. A casting process is performed on magnesium, at least one first catalytic metal, and at least one first carbon allotrope to form a first magnesium-based solid solution, where at least one first catalytic metal is selected from the group consisting of aluminum, zinc, zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium, and yttrium. A severe plastic deformation process is performed on the first magnesium-based solid solution to form a second magnesium-based solid solution. A high-energy ball milling process is performed on the second magnesium-based solid solution and an amorphous additive to form a magnesium-based composite material, where the amorphous additive includes at least one second catalytic metal and at least one second carbon allotrope, and at least one second catalytic metal is selected from the group consisting of zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium, and yttrium. The magnesium-based composite material formed by the method of the present disclosure can be used as a hydrogen carrier and has better hydrogenation and dehydrogenation performance as described above. Details of the magnesium-based composite material may not be elaborated further below. In addition to being able to form the magnesium-based composite material of the present disclosure, the method of the present disclosure is easy to implement and can mass-produce the magnesium-based composite material. Next, the method of the present disclosure will be described in detail in the following embodiments.

[0035] In the flow chart shown as Figure 1 below, the method 100 of the present disclosure includes operation 101 of performing a casting process on magnesium, at least one first catalytic metal, and at least one first carbon allotrope to form a first magnesium-based solid solution. The first magnesium-based solid solution is substantially the same as the above-mentioned magnesium-based solid solution, except that, for example, the mechanical properties of the first magnesium-based solid solution may be different and the first average grain size of the crystal structure of the first magnesium-based solid solution may be larger (refer to operation 102 below for details). In some embodiments, the first average grain size is 90 μm to 150 μm, such as 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, or 150 μm. In some embodiments, a preferred casting process includes heating magnesium, at least one first catalytic metal, and at least one first carbon allotrope at a temperature of 700 °C to 800 °C, such as 700 °C, 720 °C, 740 °C, 760 °C, 780 °C, or 800 °C, to increase the uniformity of the formed solid solution. In some embodiments, the casting process is carried out by an induction furnace to increase the efficiency of forming the solid solution and promote the mass production of the solid solution. In some embodiments, the casting process further includes stirring magnesium, at least one first catalytic metal, and at least one first carbon allotrope, and the stirring time is preferably 10 minutes to 20 minutes, such as 10 minutes, 15 minutes, or 20 minutes, to increase the uniformity of the formed solid solution. In some embodiments, the casting process is carried out in an atmosphere including sulfur hexafluoride (S F 6 ) and carbon dioxide (C O 2) carried out in an environment as a protective agent. In some embodiments, the casting process further includes being carried out in an argon environment to prevent unintended oxidation from occurring. In some embodiments, the casting process further includes quenching at room temperature, for example, the room temperature is 20 °C to 30 °C, such as 20 °C, 22 °C, 24 °C, 26 °C, 28 °C or 30 °C, to solidify the first magnesium-based solid solution.

[0036] In some embodiments, method 100 further includes performing a homogenization process after operation 101 and before operation 102. The homogenization process makes the brittle first magnesium-based solid solution formed by operation 101 more ductile. Therefore, the more ductile first magnesium-based solid solution can be more easily implemented in operation 102 to reduce the grain size of the first magnesium-based solid solution (refer to operation 102 below for details). In addition, the homogenization process increases the uniformity of the solid solution by reducing the fractures in the crystal structure of the first magnesium-based solid solution. Therefore, the second magnesium-based solid solution formed in operation 102 not only has a reduced grain size but also has limited fractures, thus enhancing the diffusion of hydrogen in the solid solution. The changes in the crystal structure after operation 101, after the homogenization process, and after operation 102 will be described in detail in the examples as shown in Figure 3A , Figure 3B and Figure 3C shown. In some embodiments, a preferred homogenization process includes heating the first magnesium-based solid solution at a temperature of 350 °C to 450 °C (such as 350 °C, 370 °C, 390 °C, 410 °C, 430 °C or 450 °C), and the duration is preferably 20 hours to 30 hours (such as 20 hours, 22 hours, 24 hours, 26 hours, 28 hours or 30 hours). In some embodiments, the heating temperature of the homogenization process is lower than the heating temperature of the casting process of operation 101. In some embodiments, the heating time of the homogenization process is longer than the heating time of the casting process of operation 101.

[0037] In some embodiments, method 100 further includes performing a water jet process after operation 101 and before operation 102. The water jet process includes cutting the first magnesium-based solid solution into strips as a preparation for operation 102. For example, in operation 102, each strip of the first magnesium-based solid solution is pressed into an angled channel to adjust the mechanical properties and grain size of the solid solution (refer to operation 102 below for details). In some embodiments, the length of each strip of the first magnesium-based solid solution is 5 mm to 15 mm, such as 11.5 mm; the width of each strip of the first magnesium-based solid solution is 5 mm to 15 mm, such as 11.5 mm; and the height of each strip of the first magnesium-based solid solution is 70 mm to 80 mm, such as 75 mm.

[0038] In as Figure 1In the flow chart shown, method 100 of the present disclosure includes operation 102 of subjecting a first magnesium-based solid solution to a severe plastic deformation process to form a second magnesium-based solid solution. The second magnesium-based solid solution is substantially the same as the magnesium-based solid solution above. For example, the second average grain size of the crystal structure of the second magnesium-based solid solution is substantially the same as the average grain size of the crystal structure of the magnesium-based solid solution above, and is smaller than the first average grain size of the crystal structure of the first magnesium-based solid solution. Since the severe plastic deformation applies strain to the first magnesium-based solid solution, the mechanical properties of the first magnesium-based solid solution are changed. At the scale of the microstructure, the grain size of the first magnesium-based solid solution is reduced. Figure 2A , Figure 2B , Figure 2C and Figure 2D are examples of severe plastic deformation processes according to some embodiments. In Figure 2A , Figure 2B , Figure 2C and Figure 2D , the severe plastic deformation process includes pressing a first magnesium-based solid solution 201 through an angled channel 202. In some embodiments, the angled channel 202 is bent and has a bend angle preferably from 90° to 120°, such as 90°, 100°, 110° or 120°. In some embodiments, the severe plastic deformation process includes repeatedly pressing the first magnesium-based solid solution 201 through the angled channel 202, and the first magnesium-based solid solution 201 does not substantially rotate along the long axis 203 between two consecutive passes (e.g. Figure 2A ), rotates 90° along the long axis 203 (e.g. Figure 2B and Figure 2C ), or rotates 180° along the long axis 203 (e.g. Figure 2D ). Figure 2B The difference between 2C and 2C is that each time the first magnesium-based solid solution 201 rotates, Figure 2B the direction of rotation changes, while Figure 2C the direction of rotation remains substantially unchanged. Specifically, in Figure 2B , the direction of rotation along the long axis 203 is clockwise after the first pass, but counterclockwise after the second pass. Specifically, in Figure 2CIn this case, after each pass, it remains clockwise or counterclockwise along the rotation direction of the long axis 203. In some embodiments, the number of times of pressing the first magnesium-based solid solution 201 through the angled channel 202 is preferably 4 to 8 times, such as 4 times, 5 times, 6 times, 7 times or 8 times. In some embodiments, the temperature of pressing the first magnesium-based solid solution 201 through the angled channel 202 is preferably 300 °C to 350 °C, such as 300 °C, 310 °C, 320 °C, 330 °C, 340 °C or 350 °C. In some embodiments, it is preferably applied to the first magnesium-based solid solution 201 at 150 kg to 250 kg to pass through the angled channel 202, such as 150 kg, 170 kg, 190 kg, 210 kg, 230 kg or 250 kg. In some embodiments, the speed of pressing the first magnesium-based solid solution 201 through the angled channel 202 is preferably 0.5 mm per second to 2.0 mm per second, such as 0.5 mm per second, 1.0 mm per second, 1.5 mm per second or 2.0 mm per second.

[0039] In some embodiments, method 100 may further include performing a filing process after operation 102 and before operation 103. The filing process includes manually grinding the second magnesium-based solid solution into granular form as a preparation for operation 103. In some embodiments, the particle size of the second magnesium-based solid solution after the filing process is preferably 80 μm to 120 μm, such as 80 μm, 90 μm, 100 μm, 110 μm or 120 μm.

[0040] In such as Figure 1In the flow chart shown, method 100 of the present disclosure includes operation 103 of performing a high-energy ball milling process on a second magnesium-based solid solution and an amorphous additive to form a magnesium-based composite material. In addition to contributing to better hydrogenation and dehydrogenation performance as described above, the amorphous additive also contributes to better obtaining the microstructure of the magnesium-based composite material in operation 103, such as the desired average particle size described above. In some embodiments, the high-energy ball milling process is performed by a high-energy ball mill (such as a planetary ball mill) to grind and mix the second magnesium-based solid solution and the amorphous additive. In some embodiments, the high-energy ball mill includes grinding balls located in a grinding jar for impacting the second magnesium-based solid solution and the amorphous additive to reduce their particle size. In some embodiments, the grinding balls are preferably steel balls. In some embodiments, the weight ratio between the weight of the grinding balls and the total weight of the second magnesium-based solid solution and the amorphous additive is preferably 30:1 to 50:1, such as 30:1, 40:1, or 50:1. In some embodiments, the rotation speed of the high-energy ball mill is preferably 200 rpm to 500 rpm, such as 200 rpm, 300 rpm, 400 rpm, or 500 rpm, to increase the impact energy applied to the second magnesium-based solid solution and the amorphous additive by applying centrifugal force to the grinding balls, the second magnesium-based solid solution, and the amorphous additive. In some embodiments, the total rotation time of the high-energy ball mill is preferably 4 hours to 16 hours, such as 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, or 16 hours. In some embodiments, the rotation direction is changed every 30 minutes and stopped for 10 minutes before the next rotation, such as rotating clockwise for 30 minutes, remaining stationary for 10 minutes, and then rotating counterclockwise for 30 minutes, etc.

[0041] The magnesium-based composite material and the method for forming the same are described in detail in the following examples. The following examples are intended to provide a better understanding of the present disclosure and are not intended to limit the scope of the present disclosure.

[0042] In Example 1, the magnesium-based composite material includes 96 wt% of a magnesium-based solid solution and 4 wt% of an amorphous additive, wherein the magnesium-based solid solution includes 92.5 wt% of magnesium, 3 wt% of aluminum, 1 wt% of zinc, 0.5 wt% of titanium, and 3 wt% of multi-walled carbon nanotubes (the density of each multi-walled carbon nanotube is about 0.057 g / cm 3), and the amorphous additive includes 40 wt% nickel and 60 wt% graphene. Magnesium, aluminum, zinc, titanium, and multi-walled carbon nanotubes are heated and stirred at 760 °C for 15 minutes in the casting process of operation 101 to obtain a first magnesium-based solid solution. The first magnesium-based solid solution is heated at 410 °C for 24 hours in the homogenization process. The first magnesium-based solid solution is cut into strips with a length of 11.5 mm, a width of 11.5 mm, and a height of 75 mm in the water jet process. In the severe plastic deformation process of operation 102, 210 kg is applied and the first magnesium-based solid solution is pressed into and passed through an angled channel with a bending angle of 120° at a speed of 1.0 mm per second. The second magnesium-based solid solution obtained from operation 102 is mixed with nickel and graphene in the high-energy ball milling process of operation 103. The weight ratio of the steel balls in the grinding tank of the high-energy ball mill to the total weight of the second magnesium-based solid solution, nickel, and graphene is 40:1, where the rotation speed of the high-energy ball mill is 400 rpm, the rotation direction is changed every 30 minutes, and it stops for 10 minutes before the next rotation.

[0043] Figure 3A , Figure 3B and Figure 3C are optical microscope images of the magnesium-based solid solution of Example 1 after operation 101, after the homogenization process, and after operation 102, respectively. Figure 3A , Figure 3B and Figure 3C clearly show the lamellar eutectic crystal structure of the solid solution. Figure 3B The fracture of the crystal structure of Figure 3A is significantly reduced compared to Figure 3A and Figure 3B . Therefore, compared with the method without the homogenization process, the cracks generated after operation 102 are restricted. In addition, compared with Figure 3C and

[0044] Figure 4A and Figure 4B are scanning electron microscope images of the magnesium-based composite material of Example 1 during and after the high-energy ball milling process. The particles are serrated during the high-energy ball milling process and are highly dispersed and have the desired particle size after the high-energy ball milling process is completed.

[0045] Example 1 is compared with Comparative Example 1. Comparative Example 1 is substantially the same as Example 1, except that Comparative Example 1 does not include operation 102 and operation 103, but Example 1 includes operation 101, operation 102, and operation 103. In other words, Comparative Example 1 only forms the first magnesium-based solid solution, while Example 1 forms a magnesium-based composite material.

[0046] Figure 5For the comparison of the X-ray diffraction patterns of Comparative Example 1 and Example 1, where curves C1 and C3 are the X-ray diffraction patterns of the first magnesium-based solid solution in Comparative Example 1 before and after hydrogenation, respectively, and curves C2 and C4 are the X-ray diffraction patterns of the magnesium-based composite material in Example 1 before and after hydrogenation, respectively. Figure 5 The symbols ◆, ┼, ▼, and ■ in 12 Mg 17 , Ni, and MgH 2 indicate the positions of the peaks. Before hydrogenation, the peaks of curve C2 are broader than those of curve C1, and the peaks of curve C2 include the peaks corresponding to Ni. After hydrogenation, curve C4 has a stronger MgH 2 peak than curve C3, and the Mg in Example 1 is substantially completely converted to MgH 2 .

[0047] Figure 6A and Figure 6B is a comparison of the hydrogen absorption and desorption capacities measured over time at a working temperature of 350 °C and a hydrogen pressure of 3 Mpa using a Sievert type constant volume equipment, where curves C5 and C7 correspond to Comparative Example 1, and curves C6 and C8 correspond to Example 1. The maximum reversible hydrogen storage capacity of Example 1 (e.g., about 6.48 wt%) is much higher than that of Comparative Example 1 (e.g., about 5.24 wt%). In addition, the hydrogen absorption rate of Example 1 (e.g., about 3.4614 wt% per minute) is much faster than that of Comparative Example 1 (e.g., about 0.0873 wt% per minute), and the hydrogen desorption rate of Example 1 (e.g., about 0.7660 wt% per minute) is also much faster than that of Comparative Example 1 (e.g., about 0.1638 wt% per minute).

[0048] The average grain sizes of the magnesium-based solid solutions in Examples 2A to 2H, Comparative Example 2I, Examples 3A to 3H, and Comparative Example 3I are compared in Table 1 below. Examples 2A to 2H are substantially the same as Example 1 above, except that the operation 102 in each example may be different. For example, the operations of Examples 2A to 2B are carried out as Figure 2A shown, where the number of repetitions of Example 2A is 4, and the number of repetitions of Example 2B is 8; the operations of Examples 2C to 2D are carried out as Figure 2B shown, where the number of repetitions of Example 2C is 4, and the number of repetitions of Example 2D is 8; the operations of Examples 2E to 2F are carried out as Figure 2CIt is carried out as shown, where the number of repetitions of Example 2E is 4, and the number of repetitions of Example 2F is 8; and the operations of Example 2G to Example 2H are carried out as Figure 2D shown, where the number of repetitions of Example 2G is 4, and the number of repetitions of Example 2H is 8. Comparative Example 2I is substantially the same as Example 1 above, except that the number of repetitions through the angled channels during operation 102 is only 1. Examples 2A to 2H have a more desirable and smaller average grain size than Comparative Example 2I. Examples 3A to 3H are respectively substantially the same as Examples 2A to 2H, except that the weight percentages of magnesium and aluminum may be different. In Examples 3A to 3H, the weight percentage of magnesium is 89.5 wt%, and the weight percentage of aluminum is 6 wt%. Comparative Example 3I is also substantially the same as Comparative Example 2I, except that the weight percentage of magnesium in Comparative Example 3I is 89.5 wt%, and the weight percentage of aluminum is 6 wt%. Examples 3A to 3H also have a more desirable and smaller average grain size than Comparative Example 3I.

[0049] Table 1

[0050] The magnesium-based composites of the present disclosure and the magnesium-based composites formed by the method of the present disclosure have better hydrogenation and dehydrogenation properties, including higher reversible hydrogen storage capacity, higher hydrogen absorption rate, higher hydrogen desorption rate, lower operating temperature, etc. The method of the present disclosure is also easy to implement, can be mass-produced, and the materials are easily available.

[0051] The present disclosure is described in detail in some embodiments, but other embodiments may also be feasible. Therefore, the description of the embodiments of the present disclosure should not limit the scope and spirit covered by the appended patent application scope.

[0052] For those of ordinary skill in the art, the present disclosure can be modified and changed without departing from the scope and spirit of the present disclosure. As long as these modifications and changes are covered by the scope and spirit of the appended patent application scope, the present disclosure also aims to cover these modifications and changes.

Symbol Description

[0053] 100: Method 101~103: Operations 201: First magnesium-based solid solution 202: Angled channel 203: Long axis C1~C8: Curves : Bending angle

Claims

1. A magnesium-based composite material, characterized in that: include: A magnesium-based solid solution comprising: magnesium; At least one first catalytic metal selected from the group consisting of aluminum, zinc, zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium and yttrium; and at least one first carbon allotrope; and An amorphous additive is mixed with the magnesium-based solid solution, wherein the amorphous additive comprises: at least one second catalytic metal selected from the group consisting of zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium and yttrium; and At least one second carbon allotrope.

2. The magnesium-based composite material as claimed in claim 1, wherein the weight percentage of the amorphous additive in the magnesium-based composite material is 1wt% to 15wt%.

3. The magnesium-based composite material as claimed in claim 1, wherein the weight percentage of each of the at least one first catalytic metal in the magnesium-based solid solution is less than or equal to 9wt%.

4. The magnesium-based composite material as claimed in claim 1, wherein when the at least one first catalytic metal comprises aluminum, the weight percentage of aluminum is the largest in the at least one first catalytic metal.

5. The magnesium-based composite material as claimed in claim 1, wherein the at least one first carbon allotrope and the at least one second carbon allotrope are independently selected from the group consisting of graphite, graphene, fullerene, single-walled carbon nanotubes, multi-walled carbon nanotubes, activated carbon and carbon black.

6. The magnesium-based composite material as claimed in claim 1, wherein a weight percentage of the at least one first carbon allotrope in the magnesium-based solid solution is less than or equal to 3 wt%.

7. The magnesium-based composite material as claimed in claim 1, wherein in the amorphous additive, a weight percentage of the at least one second carbon allotrope is greater than a weight percentage of the at least one second catalytic metal. 8 . The magnesium-based composite material as claimed in claim 1 , wherein an average particle size of the magnesium-based composite material is 20 μm to 80 μm. 9 . The magnesium-based composite material as claimed in claim 1 , wherein an average grain size in the magnesium-based solid solution is 4 μm to 34 μm. 10 . The magnesium-based composite material as claimed in claim 1 , wherein the maximum reversible hydrogen storage capacity of the magnesium-based composite material is 6 wt % to 7 wt %.

11. The magnesium-based composite material as claimed in claim 1, wherein a hydrogen absorption rate of the magnesium-based composite material is 2 wt% to 4 wt% per minute, and a hydrogen desorption rate of the magnesium-based composite material is 0.25 wt% to 1.25 wt% per minute.

12. A method for forming a magnesium-based composite material, characterized in that: include: Casting magnesium, at least one first catalytic metal and at least one first carbon allotrope to form a first magnesium-based solid solution, wherein the at least one first catalytic metal is selected from the group consisting of aluminum, zinc, zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium and yttrium; performing a severe plastic deformation process on the first magnesium-based solid solution to form a second magnesium-based solid solution; and The second magnesium-based solid solution and an amorphous additive are subjected to a high-energy ball milling process to form the magnesium-based composite material, wherein the amorphous additive comprises at least one second catalytic metal and at least one second carbon allotrope, and the at least one second catalytic metal is selected from the group consisting of zirconium, nickel, titanium, vanadium, chromium, cobalt, iron, copper, molybdenum, niobium, palladium and yttrium.

13. The method of claim 12, wherein the casting process comprises heating the magnesium, the at least one first catalytic metal and the at least one first carbon allotrope at a temperature of 700°C to 800°C.

14. The method of claim 12, further comprising performing a homogenization process after the casting process and before the severe plastic deformation process, wherein the homogenization process comprises heating the first magnesium-based solid solution at a temperature of 350°C to 450°C. 15 . The method of claim 12 , wherein a first average grain size in the first magnesium-based solid solution is greater than a second average grain size in the second magnesium-based solid solution, and the second average grain size is 4 μm to 34 μm.

16. The method of claim 12, wherein the severe plastic deformation process comprises pressing the first magnesium-based solid solution through an angled channel, and the angled channel has a bend angle of 90° to 120°.

17. The method of claim 12, wherein the severe plastic deformation process comprises repeatedly pressing the first magnesium-based solid solution through an angled channel, and the first magnesium-based solid solution is substantially not rotated, rotated by 90°, or rotated by 180° along a long axis of the first magnesium-based solid solution between two consecutive passes through the angled channel.

18. The method of claim 12, wherein the severe plastic deformation process comprises repeatedly pressing the first magnesium-based solid solution through an angled channel, and the number of repetitions is 4 to 8 times.

19. The method of claim 12, wherein the high energy ball milling process is performed by a high energy ball mill, and the rotation speed of the high energy ball mill is 200 rpm to 500 rpm.

20. The method according to claim 12, wherein the average particle size of the magnesium-based composite material is 20 μm to 80 μm.

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