CN105755302B - A kind of high-performance hydrogen bearing alloy and preparation method thereof - Google Patents

Abstract

The invention discloses a high-performance hydrogen storage alloy and a preparation method thereof. The hydrogen storage alloy Pd@Mg‑Y is formed by coating Mg _100‑x Y _x (x=20-25) alloy particles with Pd, the particle size of the alloy particles is 50-150 microns, and the thickness of the Pd film is 5-30 nm. The preparation method is as follows: preparing Mg _100-x Y _x (x=20-25) master alloy ingots by vacuum smelting, and then mechanically crushing to make hydrogen-storage alloy core particles with a particle size of 50-150 microns, and then using magnetron Sputtering coating technology evenly coats Pd film on the surface of Mg _100-x Y _x (x=20-25) core particles. The experimental results show that the hydrogen absorption and desorption rate of Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy prepared by the above method is significantly faster than that of Mg ₇₇ Y ₂₃ particles and faster than that of pure Mg of the same scale. It can be concluded that the large particle size Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy has a good application prospect in hydrogen storage materials and simplified preparation process.

Description

A kind of high-performance hydrogen storage alloy and preparation method thereof

technical field

The invention relates to a material and a preparation method thereof, in particular to a hydrogen storage alloy and a preparation method thereof.

Background technique

As a green energy, hydrogen occupies an important position in the future sustainable energy because of its cleanness, easy storage and abundant resources. So far, the key factor hindering the development of "hydrogen economy" is the storage of hydrogen. Therefore, the research and development of hydrogen storage materials has become one of the key links for the practical and large-scale utilization of hydrogen energy. As the anode material of nickel-metal hydride batteries in the largest application field, hydrogen storage alloys are required to have good discharge performance, long cycle life, and suitable hydrogen decomposition pressure. Magnesium-based hydrogen storage materials have become one of the most promising hydrogen storage materials due to their light weight, abundant reserves, low price and large hydrogen storage capacity (2200mAh/g), attracting the attention of scientists from all over the world.

However, the hydrogen storage performance of Mg-based hydrogen storage alloys is mainly affected by the particle size, the smaller the particles, the better the hydrogen absorption and desorption kinetics. Because: Mg has high reactivity to oxygen in the air. When absorbing hydrogen, a dense MgH ₂ hydride layer will be formed on the surface of the particle, and MgH ₂ has high stability. The decomposition temperature under 0.1MPa H ₂ pressure reaches 300 ℃, and the hydrogen desorption reaction rate is slow, so the further diffusion of hydrogen is hindered, and the kinetic performance of hydrogen desorption becomes poor. According to literature reports, when the thickness of the hydride layer exceeds 30-50 μm, hydrogen cannot continue to diffuse, and the absorption rate is close to zero. Therefore, the particle size of magnesium-based hydrogen storage alloys currently studied is usually less than 60 μm. The large scale of alloys is more suitable for industrial production. Therefore, improving the performance of hydrogen storage alloys with large particle size directly affects the industrial application of magnesium-based hydrogen storage alloys.

Surface modification is one of the more effective methods to improve the kinetic properties of large particle hydrogen storage alloys. Covering a layer of catalyst on the surface of the alloy can promote the dissociation and adsorption of hydrogen, thereby improving the kinetics of hydrogen absorption and desorption, and can also protect Mg from oxidation. This technical approach has shown excellent improvement effects in Mg-based thin films. However, the realization of coating on large-particle hydrogen storage alloys is rarely reported. Therefore, it is necessary to provide a technical solution for selecting which element and composition of the Mg-based hydrogen storage alloy and which coating to obtain good kinetic properties.

Invention content:

The purpose of the present invention is to provide a high-performance hydrogen storage alloy Pd@Mg-Y.

Another object of the present invention is to provide a method for preparing a Pd@Mg-Y hydrogen storage alloy.

The purpose of the present invention is achieved with the following technical solutions:

In the high-performance hydrogen storage alloy Pd@Mg-Y provided by the invention, the core composition of the alloy is Mg _100-x Y _x alloy particles, x is 20-25, and the outer surface is covered with a Pd film of uniform thickness.

In the first preferred technical solution of the alloy provided by the present invention, the particle size of the inner core Mg-Y is 50-150 microns.

In the second preferred technical solution of the alloy provided by the present invention, the thickness of the Pd film is 5-30 nm.

The preparation method of the hydrogen storage alloy Pd@Mg-Y provided by the present invention comprises the following steps:

a. Ingredients: metal Mg and metal Y are mixed according to the molar ratio of 3:1 to 4:1;

b. Preparation of master alloy: put the raw material in the graphite crucible of the smelting furnace, evacuate it, purge the furnace cavity with argon gas for 3 to 5 times, then heat to obtain a uniformly mixed Mg and Y alloy melt, and melt the The material is poured into a copper water-cooled crucible and condensed to obtain a cast Mg-Y master alloy ingot;

c, pulverizing the Mg-Y master alloy ingot made in step b, and screening through 100-300 meshes to make alloy particles with a particle size of 50-150 microns;

d. Using the Pd target as the cathode of the magnetron sputtering coating machine, the alloy particles prepared in step c are placed in the sample vibrating dish of the magnetron sputtering coating machine to form a Pd film to obtain the hydrogen storage alloy Pd@Mg-Y .

In the first preferred technical solution of the alloy preparation method, the purity of metal Mg and metal Y are both above 99.5%.

In the second preferred technical solution of the alloy preparation method, the vacuum degree of the b step is higher than 5×10 ^-4 Pa; the purity of the argon gas purging the furnace cavity is ≥99.999%; after preheating for 20-30 seconds, the Adjust the current to 120-160A to melt the alloy block, then increase the current to 200-350A, and heat for 2-3 minutes.

In the third preferred technical solution of the alloy preparation method, step c is completed in a vacuum glove box.

In the fourth preferred technical solution of the alloy preparation method, the diameter of the cathode Pd target in step d is 60-80mm, the purity is ≥99.9%; the background vacuum degree is 1× ^{10-3-2×10-3 Pa} , and the Purity ≥ 99.99% argon sputtering gas, when the argon gas flow rate is 40-80sccm, the pressure is 0.5-0.8Pa, the sputtering power is 120-200W, and the sputtering time is 120-300 seconds; the vibration frequency of the sample vibrating dish is 5 ~20Hz.

Compared with the closest prior art, the technical solution provided by the invention has the following excellent effects:

1) Compared with samples prepared by traditional methods, the Pd@Mg-Y hydrogen storage alloy prepared by the method of the present invention has the advantages of large degree of freedom in product performance index regulation, controllable quality, and superior performance;

2) The Pd@Mg-Y hydrogen storage alloy prepared by the method of the present invention has the characteristics of flexible and controllable core composition, particle diameter, and Pd film thickness of the cladding layer. The preparation process is energy-saving, environmentally friendly and pollution-free, so it is extremely suitable for industrial applications.

3) During the activation process of the Pd@Mg-Y hydrogen storage alloy provided by the present invention, the hydrogen absorption ability of Pd@Mg ₇₇ Y ₂₃ particles is better than that of Mg ₇₇ Y ₂₃ particles, and the hydrogen absorption rate is significantly faster than that of Mg ₇₇ Y ₂₃ particles. And in the subsequent hydrogen desorption process, the hydrogen desorption rate is also significantly faster than that of Mg ₇₇ Y ₂₃ particles. It shows that the kinetic performance of Mg ₇₇ Y ₂₃ particles with sputtered coating layer Pd has been greatly improved.

Description of drawings

Fig. 1 is a schematic diagram of a vibrating device provided by the present invention.

Figure 2 is the SEM morphology (a) and surface scanning EDS (b) of the Pd@Mg ₇₇ Y ₂₃ particles prepared in Example 1 of the present invention and the energy spectrum of Pd (c), Mg (d), and Y (e) Distribution.

Fig. 3 is a comparison of the hydrogen absorption and desorption curves of Pd@Mg ₇₇ Y ₂₃ particles prepared in Example 1 of the present invention and Mg ₇₇ Y ₂₃ particles.

Detailed ways

Example 1

Prepare a hydrogen storage alloy with a particle size of 60-80 μm, a coated Pd film thickness of 5 nm, and a composition of Pd@Mg ₇₇ Y ₂₃

1) Ingredients

Use metal Mg and metal Y with a purity of more than 99.5% to carry out batching according to the design composition Mg ₇₇ Y ₂₃ , and consider a certain burning loss (the burning loss of Y is set to 5wt%, and the burning loss of Mg is 15wt%);

2) Alloy melting

The Mg-Y master alloy was prepared by high-vacuum high-frequency induction melting furnace. Put the raw materials prepared in step 1) in the graphite crucible of the high-vacuum high-frequency induction melting furnace, evacuate until the background vacuum degree is higher than 5×10 ^-4 Pa, and then use argon gas with a purity ≥ 99.999% to the furnace chamber Wash the furnace 3 times, and then start heating: first turn on the power to preheat the crucible for 20 seconds, then adjust the current to 120A to completely melt the alloy block; then increase the melting current to 240A, keep it for 2 minutes, wait for the Mg and Y alloy melt After mixing evenly at high temperature, the melt is poured into a copper water-cooled crucible to condense to obtain a cast Mg-Y ingot with a certain composition.

3) Crushing treatment

The Mg-Y master alloy ingot produced in step 2) is mechanically crushed into small pieces, then ground into fine powder in an agate mortar, screened through 200 meshes, and made into alloy particles with a particle size of 60-80 microns. To avoid oxidation of the particles in the air, the crushing process was done in a vacuum glove box.

4) Pd coating by magnetron sputtering

A Pd target with a diameter of 60 mm and a purity of ≥99.9% is selected as the cathode of the magnetron sputtering coating machine. Place the core alloy particles made in step 3) in the sample vibrating dish in the magnetron sputtering coating machine. The schematic diagram of the sample vibrating dish is shown in Figure 1.

Set the sputtering coating parameters as follows: background vacuum degree 1×10 ^-3 Pa, use argon gas with purity ≥99.99% as the sputtering gas, argon gas flow rate of 50 sccm, working pressure of 0.6 Pa, sputtering power of 150W, sputtering The coating time is 180 seconds. During the coating process, the vibration frequency of the sample vibrating dish was 5 Hz, and the Pd film-coated Mg ₇₇ Y ₂₃ alloy particles were made, that is, the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy.

The results of energy spectrum analysis show that the core composition ratio of the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy prepared by the above steps is Mg _76.8 Y _23.2 , indicating that the composition of the mother ingot is basically the same as the design ratio; combined with the observation of the microscopic morphology of the cross-section of the particles, it can be known that Pd The film thickness is about 5nm, which meets the design requirements.

Figure 3 is the comparison of hydrogen absorption kinetic curves _of Pd@Mg ₇₇ Y ₂₃ alloy for the first time at 350 °C and 2 MPa hydrogen pressure. It can be seen that the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy prepared by the above process is more The hydrogen absorption capacity of the ₂₃ alloy is increased by 23%, and the hydrogen absorption rate is increased by 30% (based on reaching 80% of the saturated hydrogen absorption capacity). And in the subsequent dehydrogenation process, the hydrogen desorption rate of the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy is 42% faster than that of the Mg ₇₇ Y ₂₃ alloy (calculated to reach 80% of the hydrogen desorption amount).

Example 2

Prepare a hydrogen storage alloy with a particle size of 100-120 μm, a coated Pd film thickness of 10 nm, and a composition of Pd@Mg ₇₇ Y ₂₃

1) Ingredients

Use metal Mg and metal Y with a purity of more than 99.5% to carry out batching according to the design composition Mg ₇₇ Y ₂₃ , and consider a certain burning loss (the burning loss of Y is set to 5wt%, and the burning loss of Mg is 15wt%);

2) Alloy melting

The Mg-Y master alloy was prepared by high-vacuum high-frequency induction melting furnace. Put the raw materials prepared in step 1) in the graphite crucible of the high-vacuum high-frequency induction melting furnace, evacuate until the background vacuum degree is higher than 5×10 ^-4 Pa, and then use argon gas with a purity ≥ 99.999% to the furnace chamber Wash the furnace 3 times, and then start heating: first turn on the power to preheat the crucible for 20 seconds, then adjust the current to 120A to completely melt the alloy block; then increase the melting current to 240A, keep it for 2 minutes, wait for the Mg and Y alloy melt After mixing evenly at high temperature, the melt is poured into a copper water-cooled crucible to condense to obtain a cast Mg-Y ingot with a certain composition.

3) Crushing treatment

The Mg-Y master alloy ingot produced in step 2) is mechanically crushed into small pieces, then ground into fine powder in an agate mortar, and screened through 120 mesh to produce alloy particles with a particle size of 100-120 microns. To avoid oxidation of the particles in the air, the crushing process was done in a glove box.

4) Pd coating by magnetron sputtering

A Pd target with a diameter of 60 mm and a purity of ≥99.9% is selected as the cathode of the magnetron sputtering coating machine. Place the core alloy particles made in step 3) in the sample vibrating dish in the magnetron sputtering coating machine. The schematic diagram of the sample vibrating dish is shown in Figure 1.

Set the sputtering coating parameters as follows: background vacuum degree 1×10 ^-3 Pa, use argon gas with purity ≥99.99% as the sputtering gas, argon gas flow rate of 50 sccm, working pressure of 0.6 Pa, sputtering power of 150W, sputtering The coating time is 360 seconds. During the coating process, the vibration frequency of the sample vibrating dish was 5 Hz, and the Pd film-coated Mg ₇₇ Y ₂₃ alloy particles were made, that is, the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy.

The results of energy spectrum analysis show that the core composition ratio of the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy prepared by the above steps is Mg _76.9 Y _23.1 , indicating that the composition of the mother ingot is basically the same as the design ratio; according to inductively coupled plasma atomic emission spectroscopy (ICP- The Pd content was determined by AES) composition and combined with the particle morphology, the Pd film thickness was estimated to be about 10nm, which met the design requirements.

From the hydrogen absorption and desorption kinetic curves of hydrogen storage alloys, it can be seen that the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy prepared by the above process has a 27% increase in hydrogen absorption capacity and a 33% increase in hydrogen absorption rate compared with Mg ₇₇ Y ₂₃ alloy (to achieve saturated hydrogen absorption 80% of the amount). And in the subsequent dehydrogenation process, the hydrogen desorption rate of the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy is 46% faster than that of the Mg ₇₇ Y ₂₃ alloy (calculated to reach 80% of the hydrogen desorption amount).

Example 3

Prepare a hydrogen storage alloy with a particle size of 60-80 μm, a coated Pd film thickness of 20 nm, and a composition of Pd@Mg ₇₇ Y ₂₃

1) Ingredients

Use metal Mg and metal Y with a purity of more than 99.5% to carry out batching according to the design composition Mg ₇₇ Y ₂₃ , and consider a certain burning loss (the burning loss of Y is set to 5wt%, and the burning loss of Mg is 15wt%);

2) Alloy melting

The Mg-Y master alloy was prepared by high-vacuum high-frequency induction melting furnace. Put the raw materials prepared in step 1) in the graphite crucible of the high-vacuum high-frequency induction melting furnace, evacuate until the background vacuum degree is higher than 5×10 ^-4 Pa, and then use argon gas with a purity ≥ 99.999% to the furnace chamber Wash the furnace 3 times, and then start heating: first turn on the power to preheat the crucible for 20 seconds, then adjust the current to 120A to completely melt the alloy block; then increase the melting current to 240A, keep it for 2 minutes, wait for the Mg and Y alloy melt After mixing evenly at high temperature, the melt is poured into a copper water-cooled crucible to condense to obtain a cast Mg-Y ingot with a certain composition.

3) Crushing treatment

The Mg-Y master alloy ingot produced in step 2) is mechanically crushed into small pieces, then ground into fine powder in an agate mortar, screened through 200 meshes, and made into alloy particles with a particle size of 60-80 microns. To avoid oxidation of the particles in the air, the crushing process was done in a glove box.

4) Pd coating by magnetron sputtering

A Pd target with a diameter of 60 mm and a purity of ≥99.9% is selected as the cathode of the magnetron sputtering coating machine. Place the core alloy particles made in step 3) in the sample vibrating dish in the magnetron sputtering coating machine. The schematic diagram of the sample vibrating dish is shown in Figure 1.

Set the sputtering coating parameters as follows: background vacuum degree 1×10 ^-3 Pa, use argon gas with purity ≥99.99% as the sputtering gas, argon gas flow rate of 50 sccm, working pressure of 0.6 Pa, sputtering power of 150W, sputtering The coating time is 180 seconds. During the coating process, the vibration frequency of the sample vibrating dish was 5 Hz, and the Pd film-coated Mg ₇₇ Y ₂₃ alloy particles were made, that is, the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy.

The results of energy spectrum analysis show that the core composition ratio of the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy prepared by the above steps is Mg _76.8 Y _23.2 , indicating that the composition of the mother ingot is basically the same as the design ratio; combined with the observation of the microscopic morphology of the cross-section of the particles, it can be known that Pd The film thickness is about 20nm, which meets the design requirements.

From the hydrogen absorption and desorption kinetic curves of the hydrogen storage alloy, it can be seen that the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy prepared by the above process has a 31% higher hydrogen absorption capacity than the Mg ₇₇ Y ₂₃ alloy, and a 35% increase in the hydrogen absorption rate (to achieve saturated hydrogen absorption 80% of the amount). And in the subsequent dehydrogenation process, the hydrogen desorption rate of the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy is 48% faster than that of the Mg ₇₇ Y ₂₃ alloy (calculated to reach 80% of the hydrogen desorption capacity).

Example 4

Prepare a hydrogen storage alloy with a particle size of 100-120 μm, a Pd-coated film thickness of 30 nm, and a composition of Pd@Mg ₇₇ Y ₂₃

1) Ingredients

Use metal Mg and metal Y with a purity of more than 99.5% to carry out batching according to the design composition Mg ₇₇ Y ₂₃ , and consider a certain burning loss (the burning loss of Y is set to 5wt%, and the burning loss of Mg is 15wt%);

2) Alloy melting

The Mg-Y master alloy was prepared by high-vacuum high-frequency induction melting furnace. Put the raw materials prepared in step 1) in the graphite crucible of the high-vacuum high-frequency induction melting furnace, evacuate until the background vacuum degree is higher than 5×10 ^-4 Pa, and then use argon gas with a purity ≥ 99.999% to the furnace chamber Wash the furnace 3 times, and then start heating: first turn on the power to preheat the crucible for 20 seconds, then adjust the current to 120A to completely melt the alloy block; then increase the melting current to 240A, keep it for 2 minutes, wait for the Mg and Y alloy melt After mixing evenly at high temperature, the melt is poured into a copper water-cooled crucible to condense to obtain a cast Mg-Y ingot with a certain composition.

3) Crushing treatment

The Mg-Y master alloy ingot produced in step 2) is mechanically crushed into small pieces, then ground into fine powder in an agate mortar, and screened through 120 mesh to produce alloy particles with a particle size of 100-120 microns. To avoid oxidation of the particles in the air, the crushing process was done in a glove box.

4) Pd coating by magnetron sputtering

A Pd target with a diameter of 60 mm and a purity of ≥99.9% is selected as the cathode of the magnetron sputtering coating machine. Place the core alloy particles made in step 3) in the sample vibrating dish in the magnetron sputtering coating machine. The schematic diagram of the sample vibrating dish is shown in Figure 1.

Set the sputtering coating parameters as follows: background vacuum degree 1×10 ^-3 Pa, use argon gas with purity ≥99.99% as the sputtering gas, argon gas flow rate of 50 sccm, working pressure of 0.6 Pa, sputtering power of 150W, sputtering The coating time is 360 seconds. During the coating process, the vibration frequency of the sample vibrating dish was 5 Hz, and the Pd film-coated Mg ₇₇ Y ₂₃ alloy particles were made, that is, the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy.

The results of energy spectrum analysis show that the core composition ratio of the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy prepared by the above steps is Mg _76.9 Y _23.1 , indicating that the composition of the mother ingot is basically the same as the design ratio; according to inductively coupled plasma atomic emission spectroscopy (ICP- The Pd content was determined by AES) composition and combined with the particle morphology, the thickness of the Pd film was estimated to be about 30nm, which met the design requirements.

From the hydrogen absorption and desorption kinetic curves of the hydrogen storage alloy, it can be seen that the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy prepared by the above process is 28% higher than the Mg ₇₇ Y ₂₃ alloy in hydrogen absorption capacity, and the hydrogen absorption rate is increased by 32% (to achieve saturated hydrogen absorption 80% of the amount). And in the subsequent dehydrogenation process, the hydrogen desorption rate of the Pd@Mg ₇₇ Y ₂₃ hydrogen storage alloy is 45% faster than that of the Mg ₇₇ Y ₂₃ alloy (calculated to reach 80% of the hydrogen desorption capacity).

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Those of ordinary skill in the art should understand that the specific implementation methods of the present invention can be modified or equivalently replaced with reference to the above embodiments without departing from the spirit of the present invention. Any modification or equivalent replacement of the scope and scope is within the protection scope of the pending claims.

Claims (6)

1. a kind of high-performance hydrogen bearing alloy Pd Mg-Y, it is characterised in that interior nuclear composition is Mg_100-xY_xAlloying pellet, x be 20~ 25, outer surface is coated with the Pd films of uniform thickness；

The granularity of kernel Mg-Y is 50~150 microns；

Pd film thicknesses are 5~30nm.

2. the preparation method of hydrogen bearing alloy Pd@Mg-Y as described in claim 1, comprises the following steps：

A, dispensing：Metal Mg and metal Y is 3 according to molar ratio:1~4:1 ratio dispensing；

B, master alloy is prepared：Raw material is placed in the graphite crucible of smelting furnace, is vacuumized, furnace chamber is purged 3~5 times with argon gas, Then heating obtains uniformly mixed Mg and y alloy molten liquid, and melting charge is poured into copper cold-crucible and is condensed, as cast condition is obtained Mg-Y master alloy ingots；

C, Mg-Y master alloy ingots made of step b are crushed, crosses the screening of 100~300 mesh, it is 50~150 microns that granularity, which is made, Alloying pellet；

D, using Pd targets as the cathode of magnetron sputtering coater, alloying pellet made from step c is placed on magnetron sputtering coater Sample vibrates in ware, is coated with Pd films, obtains hydrogen bearing alloy Pd@Mg-Y.

3. the preparation method of hydrogen bearing alloy Pd@Mg-Y as claimed in claim 2, which is characterized in that metal Mg's and metal Y is pure Degree is 99.5% or more.

4. the preparation method of hydrogen bearing alloy Pd@Mg-Y as claimed in claim 2, which is characterized in that the vacuum degree of the b step Higher than 5 × 10^-4Pa；Purge purity of argon >=99.999% of furnace chamber；After preheating 20~30 seconds, electric current is adjusted to 120~ Electric current is risen to 200~350A by 160A again after so that alloy block is melted, and is heated 2~3 minutes.

5. the preparation method of hydrogen bearing alloy Pd@Mg-Y as claimed in claim 2, it is characterised in that step c is in vacuum glove It is completed in case.

6. the preparation method of hydrogen bearing alloy Pd@Mg-Y as claimed in claim 2, which is characterized in that cathode Pd described in step d Target diameter is 60~80mm, purity >=99.9%；Background vacuum 1 × 10^-3~2 × 10^-3Pa, with the argon gas of purity >=99.99% Sputter gas is 40~80sccm in argon flow amount, and pressure is under 0.5~0.8Pa, and sputtering power is sputtering under 120~200W 120~300 seconds；It is 5~20Hz that sample, which vibrates ware vibration frequency,.