CN111996429A - La-Y-Mg-Ni quaternary hydrogen storage alloy with high hydrogen absorption and desorption rate and preparation method thereof - Google Patents

Abstract

The invention relates to a La-Y-Mg-Ni quaternary hydrogen storage alloy with high hydrogen absorption and desorption rate and a preparation method thereof, wherein the hydrogen storage alloy comprises La-Y-Mg-Ni master alloy and an additive TiF₃Composition of the master alloy with La as the atomic ratio_aY_bMg_cNi_dWherein a is 1.5 to 1.9, b is 0.1 to 0.5, c is 15 to 17, and d is 1; additive TiF₃Is nano particles, and the content of the nano particles is 0-10 wt% of the mass of the master alloy. The key of the preparation method is that the master alloy is subjected to high-energy ball milling, and the nano-scale TiF is added in the middle₃And continuously ball-milling the particles to obtain the alloy powder with the amorphous nanocrystalline structure. TiF of the invention₃Can reduce the bond energy of Mg-H bond, and TiF₃The nanoparticles may be H atoms bonded to H₂The molecules provide nucleation sites, so that the alloy has a higher hydrogen storage capacity and a faster gaseous hydrogen absorption and desorption rate.

Description

La-Y-Mg-Ni quaternary hydrogen storage alloy with high hydrogen absorption and desorption rate and preparation method thereof

technical field

The invention belongs to the technical field of hydrogen storage alloy materials, in particular to a La-Y-Mg-Ni quaternary hydrogen storage alloy with high hydrogen absorption and desorption rate and a preparation method thereof.

Background technique

As the world's population increases rapidly, technology and the economy develops rapidly, the rate of energy consumption also accelerates. At present, the main energy consumed in the world is fossil energy, but the reserves of fossil energy are limited, and a large amount of waste pollutants will be produced in the process of production and use, causing serious damage to the ecosystem. To this end, countries around the world have invested a lot of energy in the research and development of green and pollution-free new energy sources to replace fossil energy.

Among many new energy sources, hydrogen is a promising renewable green energy, which is mainly due to the advantages of hydrogen. Hydrogen is the most common element in nature, with abundant reserves. Hydrogen has a high calorific value, and the product after combustion is water, which is clean and pollution-free. The commercial application of hydrogen energy mainly includes three links: preparation, storage and application. Among them, hydrogen storage is the key link. Compared with the traditional gaseous and liquid hydrogen storage, the new solid-state hydrogen storage has great advantages, such as high hydrogen storage capacity per unit volume, high safety, and high hydrogen purity. Among many solid-state hydrogen storage materials, magnesium has the largest saturated hydrogen absorption capacity (about 7.6 wt.% H in MgH ₂ ), and is one of the most promising hydrogen storage materials due to its abundant resources, low price and long cycle life. . At the same time, elemental magnesium also has some areas that need to be improved, including high reaction temperature, poor kinetic performance, and easy oxidation. Among them, how to reduce the reaction temperature and speed up the rate of hydrogen absorption and desorption are the two main aspects of the study.

Studies have shown that the hydrogen storage properties of Mg-based alloys can be effectively improved by alloying, surface modification, and adding additives. However, there is no report on the application of La-Y-Mg-Ni quaternary alloy in hydrogen storage.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a La-Y-Mg-Ni quaternary alloy with both high hydrogen storage capacity and high hydrogen absorption and desorption rate and a preparation method thereof. According to the invention, elemental Mg is alloyed with La, Y and Ni, the surface of the alloy is modified by ball milling, and _TiF3 is added as an additive to the alloy powder, so that the hydrogen storage performance of the Mg-based alloy is significantly improved.

The purpose of this invention is to realize through following technical scheme:

A La-Y-Mg-Ni quaternary hydrogen storage alloy with high hydrogen absorption and desorption rate, the hydrogen storage alloy is composed of La-Y-Mg-Ni master alloy and additive _TiF3 , La-Y-Mg-Ni master alloy The composition of the atomic ratio is La _a Y _b Mg _c Ni _d , wherein a is 1.5-1.9, b is 0.1-0.5, c is 15-17, and d is 1; the additive TiF ₃ is nano-particles, and the content is La-Y % of the mass of the Mg-Ni master alloy; the main phase of the hydrogen storage alloy is La ₂ Mg ₁₇ , and the second phase contains La ₂ Ni ₃ , Mg ₂ Ni, MgF ₂ and TiF ₂ ; When the content of ₃ is 0, there are only La ₂ Mg ₁₇ , La ₂ Ni ₃ and Mg ₂ Ni phases in the alloy.

Among them, a is 1.7-1.8, b is 0.2-0.3, c is 15.5-16.5, and d is 1.

The hydrogen storage alloy has an amorphous nanocrystalline structure.

The hydrogen storage alloy is prepared by the following method: under a protective atmosphere, the La-Y-Mg-Ni master alloy is smelted in a vacuum induction melting furnace, the obtained as-cast alloy is subjected to mechanical crushing and high-energy ball milling, and then an appropriate amount of TiF ₃ nanometers is added. The particles are then ball-milled to obtain an alloy powder with an amorphous nanocrystalline structure.

By adjusting the content of TiF ₃ , the hydrogen absorption time required for the hydrogen storage alloy to reach 80% saturated hydrogen absorption capacity at 50°C is 0.4-35 minutes, and the hydrogen desorption activation energy of the alloy is 56.6-69.5 kJ/mol.

A preparation method of La-Y-Mg-Ni quaternary hydrogen storage alloy alloy with high hydrogen absorption and desorption rate as described, the steps of the preparation method include:

① Batching: according to the atomic ratio composition of the master alloy La _a Y _b Mg _c Ni _d , the batching is carried out, wherein a is 1.5-1.9, b is 0.1-0.5, c is 15-17, d is 1, and the purity of raw materials is required to be ≥99.5% ;

②Preparation of master alloy: Melt the prepared raw materials in a vacuum induction melting furnace. Before melting, the furnace is evacuated to 1×10 ^-3 Pa, and then filled with high-purity helium gas with a purity of 99.999% until the pressure in the furnace reaches 0.04±0.01MPa, then start to heat up and smelt to obtain molten La _a Y _b Mg _c Ni _d alloy, after holding for 10 ± 3 minutes, pour the molten alloy into a copper mold and cool it with the furnace to obtain as-cast La _1.7 Y _0.3 Mg ₁₆ Ni master alloy;

③ High-energy ball milling: The as-cast mother La _a Y _b Mg _c Ni _d alloy is crushed to 300 mesh to obtain alloy powder. The alloy powder and the grinding ball are added to the planetary ball mill at a mass ratio of 1:40, and the Protective gas, and then carry out high-energy ball milling at a speed of 350r/min, and the ball milling time is 10±1 hours;

④ Add TiF ₃ : After the alloy powder is ball-milled for 10±1 hours, open the ball-milling jar, add an appropriate amount of TiF ₃ nanoparticles, then close the ball-milling jar, fill with argon, and continue the ball-milling for 5±1 hours to obtain amorphous nano-particles. Alloy powder with crystal structure.

In step ①, the actual addition amount of rare earth and Mg is 5% and 8% more than the ratio in the chemical formula, respectively.

In step ③, in order to prevent the sintering of the alloy powder in the ball milling process, the ball mill will be stopped for t hours every t hours of operation, then run in reverse for t hours, and then stop for t hours, and so on, until the set total ball milling time, t=0.4 ~0.6 hours.

In step ④, the timing of adding TiF ₃ is when there is still 5±1 hours left in the total ball milling time.

Compared with the prior art, the beneficial effects of the present invention are:

A new type of La-Y-Mg-Ni quaternary hydrogen storage alloy is designed, which contains two rare earth elements (lanthanum and yttrium) and one transition group element (nickel), which provides a basis for the design of hydrogen storage alloys. The new direction, by alloying with La, Y, and Ni, weakens the Mg-H bond and reduces the thermal stability of Mg-based hydrides. The surface of the alloy is modified by high-energy ball milling to reduce the alloy grains and form an amorphous nanocrystalline structure, which generates active sites with low activation energy on the surface of the alloy, and promotes the diffusion rate of H on the surface and inside of the alloy. _TiF3 nanoparticles are used as additives, in which Ti can weaken Mg-H bonds and reduce the thermal stability of Mg-based hydrides. At the same time, _TiF3 reacts with Mg _- based alloys during ball milling and generates MgF2 and _TiF2 in situ, The formation of active sites is beneficial to improve the kinetics of hydrogen absorption and desorption of Mg-based alloys. Through the comprehensive utilization of various technologies, not only the thermal stability of Mg-based hydrides is reduced, thereby reducing the decomposition temperature of metal hydrides, but also a large number of defects and active sites are generated in the alloy through surface modification and addition of additives. It provides a channel for the diffusion of H on the surface and inside of the alloy, which significantly improves the hydrogen absorption and desorption kinetics of the alloy.

The invention comprehensively utilizes various methods to prepare the La-Y-Mg-Ni quaternary alloy with higher hydrogen absorption and desorption rate. The transition group element Ni and rare earth elements La and Y are added to elemental Mg for alloying treatment to prepare La _a Y _b Mg _c Ni _d alloy. In the process of hydrogen absorption and desorption, the unsaturated d-layer electrons of alloying elements interact with the valence electrons of H, weakening the strength of the Mg-H bond, thereby improving the hydrogen storage performance of Mg-based alloys. The alloys are surface treated by mechanical ball milling technology to change the surface properties, microstructure and grain size of the alloys. Mechanical ball milling makes the alloy powder form an amorphous nanocrystalline structure, which generates new defects inside and on the surface of the material. Active sites with low activation energy are easily formed at the defects, which is conducive to the diffusion of H in the material. During the ball milling process, _TiF3 nanoparticles were added to the alloy powder as an additive, and were uniformly mixed by ball milling. Ti in _TiF3 has unsaturated 3d layer electrons, the valence electron interaction with H will weaken the Mg-H bond, in addition, _TiF3 reacts with Mg _- based alloys during ball milling and generates MgF2 and _TiF2 in situ , forming active sites with low activation energy and promoting the hydrogen absorption and desorption kinetic properties of the alloy.

Description of drawings

Fig. 1 is the XRD diffraction spectrum of embodiment 1～6 of the present invention and comparative example;

Fig. 2 is the microscopic appearance of embodiment 2 of the present invention under scanning electron microscope (SEM);

Fig. 3 is the microscopic morphology and electron diffraction pattern of embodiment 2 of the present invention under the high magnification transmission electron microscope (HRTEM);

Fig. 4 is the microscopic appearance of embodiment 6 of the present invention under scanning electron microscope (SEM);

Fig. 5 is the microscopic morphology and electron diffraction pattern of embodiment 6 of the present invention under high magnification transmission electron microscope (HRTEM);

Fig. 6 is the microscopic appearance of the comparative example of the present invention under scanning electron microscope (SEM);

FIG. 7 is the microscopic morphology and electron diffraction pattern of the comparative example of the present invention under high magnification transmission electron microscope (HRTEM).

Detailed ways

The design idea and mechanism of the present invention will be further described below with reference to the embodiments and accompanying drawings, so as to make the technical solution of the present invention clearer.

The invention provides a La-Y-Mg-Ni quaternary alloy with high hydrogen absorption and desorption rate. The composition of the hydrogen storage alloy is La _a Y _b Mg _c Ni _d +x wt.% TiF ₃ , where a is 1.5～1.9, b is 0.1～0.5, c is 15～17, d is 1, a, b, c, d are all atomic ratios of alloy elements, x is TiF ₃ nanoparticles in La _a Y _b Mg _c Ni _d The mass ratio in the alloy, and x=0～10. The main phase of the hydrogen storage alloy is La ₂ Mg ₁₇ , the second phase includes La ₂ Ni ₃ , Mg ₂ Ni, MgF ₂ and TiF ₂ , and when the TiF ₃ content is 0, there is no MgF ₂ and TiF ₂ in the alloy. Mutually. By ball milling and adjusting the alloy composition and TiF ₃ content, the time it takes for the La _a Y _b Mg _c Ni _d alloy to reach saturation for the first time is shortened from 19 hours to 7 hours, and the time required for the alloy to reach 80% saturated hydrogen absorption at 50°C The hydrogen absorption time of the alloy was shortened from 296 minutes to 0.4 minutes, and the hydrogen desorption activation energy of the alloy was reduced from 70.5kJ/mol to 56.6kJ/mol.

The present invention finds through research that adding transition group metal elements and rare earth elements to elemental Mg can reduce the bond energy of the Mg-H bond, thereby reducing the thermal stability of magnesium hydride, thereby improving its hydrogen absorption and desorption kinetic performance. Through high-energy ball milling, the particle size and grain size of the alloy will be reduced, and a large number of nano-grains and crystal defects will appear in the alloy, forming an amorphous nano-crystalline structure, which provides a channel for the diffusion of H on the surface and inside of the alloy, which is beneficial to Improve the hydrogen absorption and desorption kinetic properties of the alloy. The selection of _TiF3 as an additive can not only weaken the Mg-H bond and reduce the stability of metal hydrides, but also generate a large number of nano-grains in situ, providing a good nucleation site and H for the hydrogen absorption and desorption reactions of the alloy. Diffusion channel to accelerate the hydrogen absorption and desorption reaction.

The present invention is a Mg-based hydrogen storage material with high hydrogen absorption and desorption rate, and its chemical expression is: La _a Y _b Mg _c Ni _d +xwt.%TiF ₃ , wherein a is 1.5-1.9, b is 0.1-0.5, c is 15-17, d is 1, a, b, c, and d are the atomic ratios of alloy elements, x is the mass percentage of _TiF3 nanoparticles in the alloy, and x=0-10. The preparation method of the rapid hydrogen absorption and desorption Mg-based hydrogen storage material of the present invention comprises the following steps:

① Batching: according to the chemical expression of the alloy La _a Y _b Mg _c Ni _d , the raw material purity is ≥ 99.5%, and the rare earth La and Y need to add 5% more burning loss, and Mg should add 8% more burning loss;

②Preparation of master alloy: put the prepared alloy raw materials into the vacuum induction melting furnace, cover the furnace cover for sealing, then vacuum the furnace to 1×10 ^-3 Pa, and then fill it with high-purity 99.999% pure The pressure in the furnace reaches 0.04MPa with helium gas, and then the temperature rises and smelts until all the raw materials are melted to obtain a molten La-Y-Mg-Ni alloy. After holding for 10 minutes, the molten alloy is injected into the copper mold and cooled with the furnace. Obtain as-cast La _a Y _b Mg _c Ni _d alloy;

③High-energy ball milling: mechanically crush the as-cast La _a Y _b Mg _c Ni _d alloy to 300 mesh to obtain alloy powder, add the alloy powder and stainless steel grinding balls into the ball mill in a mass ratio of 1:40, and fill the ball mill tank with Argon was introduced as protective gas, and then the ball mill was installed on the planetary ball mill, and high-energy ball milling was carried out at a speed of 350 r/min. In order to prevent the alloy powder from sintering in the ball milling process, the ball mill will stop for 0.5 hours every 0.5 hours, then run in reverse for 0.5 hours, and then stop for 0.5 hours, and so on, until the total ball milling time reaches 10 hours;

④ Add TiF ₃ : After the alloy powder was ball-milled for 10 hours, open the ball-milling jar, add an appropriate amount of TiF ₃ nanoparticles, then close the ball-milling jar, fill with argon, and continue ball-milling at 350 r/min for 5 hours to obtain a Hydrogen storage alloy powder with crystalline and nanocrystalline structure;

⑤Structure and performance testing: XRD was used to test the phase composition of the alloy powder, SEM and TEM were used to observe the surface state and microstructure of the alloy powder, and the fully automatic Sieverts equipment was used to test the hydrogen storage capacity, hydrogen absorption and desorption rate of the alloy powder and other gaseous hydrogen storage performance.

The chemical composition and comparative example of the specific embodiment of the present invention are selected as follows:

Example 1: La _1.8 Y _0.2 Mg ₁₆ Ni (ball milling for 15 hours)

Example 2: La _1.7 Y _0.3 Mg ₁₆ Ni (ball milling for 15 hours)

Example 3: La _1.8 Y _0.2 Mg ₁₆ Ni + 3wt.% TiF ₃ (ball milling for 15 hours)

Example 4: La _1.7 Y _0.3 Mg ₁₆ Ni + 5wt.% TiF ₃ (ball milling for 15 hours)

Example 5: La _1.8 Y _0.2 Mg ₁₆ Ni + 7wt.% TiF ₃ (ball milling for 15 hours)

Example 6: La _1.7 Y _0.3 Mg ₁₆ Ni + 10 wt.% TiF ₃ (ball milling for 15 hours)

Comparative example: La _1.7 Y _0.3 Mg ₁₆ Ni (as-cast)

In the following, the specific process parameters and processes of the listed examples and comparative examples will be described.

Example 1

The alloy composition is La _1.8 Y _0.2 Mg ₁₆ Ni. The bulk metal La, metal Y, metal Mg and metal Ni with a purity of ≥99.5% were selected and weighed. Among them, Ni is weighed according to the stoichiometric ratio, La and Y add 5% more burn loss on the basis of the stoichiometric ratio, and Mg add 8% more burn loss on the basis of the stoichiometric ratio. The maximum capacity of the magnesia crucible in the vacuum induction melting furnace is 2 kg, and the alloy raw materials are calculated with a total weight of 1.5 kg. The calculated weights of metals La, Y, Mg and Ni are 550.42 grams, 39.14 grams, 880.70 grams and 123.04 grams, respectively, and the total weight of the raw materials is 1593.31 grams. Place the weighed raw materials in the magnesia crucible of the vacuum induction melting furnace, cover the furnace cover and evacuate to 1×10 ^-3 Pa, and then fill with 0.04MPa high-purity helium gas with a purity of 99.999% as the protective gas . Heating to 650°C with a power of 5kW melts the metal Mg, and then heating to 1600°C with a power of 25kW to melt the entire metal to form a molten alloy. After the alloy was kept in a molten state for 10 minutes, the alloy liquid was poured into a copper mold and cooled to room temperature with the furnace to obtain a cylindrical cast alloy with a diameter of 3 cm.

Select an appropriate amount of as-cast La _1.8 Y _0.2 Mg ₁₆ Ni alloy, and pass through a 300-mesh sieve after mechanical crushing. Weigh 5 grams of 300 mesh alloy powder and put it into a stainless steel ball mill jar. Weigh 200 grams of stainless steel grinding balls, including 2 20mm grinding balls, 10 10mm grinding balls, and the rest are 6mm grinding balls, and put them into a ball mill jar with alloy powder. After the ball mill jar was sealed, it was filled with high-purity argon gas with a purity of 99.999%. According to this step, prepare three more ball mill jars with a ball-to-material ratio of 40:1. Four ball mill jars were installed on the planetary ball mill, the rotational speed was set to 350 r/min, and the ball milling time was 15 hours. In the ball milling process, first ball mill for 0.5 hours, then stop for 0.5 hours, then reverse ball mill for 0.5 hours, then stop for 0.5 hours, and so on, until the total ball milling time reaches 15 hours. After the ball milling, the ball milling jar was opened to obtain a La _1.8 Y _0.2 Mg ₁₆ Ni alloy sample that was ball-milled for 15 hours.

The phase composition of the alloy powder was tested by XRD, and the results are shown in Figure 1. The surface state and microstructure of the alloy powders were observed by SEM and TEM. The gaseous hydrogen storage properties such as hydrogen storage capacity and hydrogen absorption and desorption rate of the alloy powder were tested by automatic Sieverts equipment. The results are shown in Table 1.

Example 2

The alloy composition is La _1.7 Y _0.3 Mg ₁₆ Ni. The bulk metal La, metal Y, metal Mg and metal Ni with a purity of ≥99.5% were selected and weighed. Among them, Ni is weighed according to the stoichiometric ratio, La and Y add 5% more burn loss on the basis of the stoichiometric ratio, and Mg add 8% more burn loss on the basis of the stoichiometric ratio. The maximum capacity of the magnesia crucible in the vacuum induction melting furnace is 2 kg, and the alloy raw materials are calculated with a total weight of 1.5 kg. The calculated weights of metals La, Y, Mg and Ni are 523.50 grams, 59.13 grams, 886.90 grams and 123.91 grams, respectively, and the total weight of the raw materials is 1593.44 grams. Place the weighed raw material in the magnesia crucible of the vacuum induction melting furnace, cover the furnace cover, evacuate to 1×10 ^-3 Pa, and then fill in 0.04MPa high-purity helium with a purity of 99.999% as the protective gas . Heating to 650°C with a power of 5kW melts the metal Mg, and then heating to 1600°C with a power of 25kW to melt the entire metal to form a molten alloy. After the alloy was kept in a molten state for 10 minutes, the alloy liquid was poured into a copper mold and cooled to room temperature with the furnace to obtain a cylindrical cast alloy with a diameter of 3 cm.

Select an appropriate amount of as-cast La _1.7 Y _0.3 Mg ₁₆ Ni alloy, and pass through a 300-mesh sieve after mechanical crushing. Weigh 5 grams of 300 mesh alloy powder and put it into a stainless steel ball mill jar. Weigh 200 grams of stainless steel grinding balls, including 2 20mm grinding balls, 10 10mm grinding balls, and the rest are 6mm grinding balls, and put them into a ball mill jar with alloy powder. After the ball mill jar was sealed, it was filled with high-purity argon gas with a purity of 99.999%. According to this step, prepare three more ball mill jars with a ball-to-material ratio of 40:1. Four ball mill jars were installed on the planetary ball mill, the rotational speed was set to 350 r/min, and the ball milling time was 15 hours. In the ball milling process, first ball mill for 0.5 hours, then stop for 0.5 hours, then reverse ball mill for 0.5 hours, then stop for 0.5 hours, and so on, until the total ball milling time reaches 15 hours. After the ball-milling, the ball-milling jar was opened to obtain a La _1.7 Y _0.3 Mg ₁₆ Ni alloy sample that was ball-milled for 15 hours.

The phase composition of the alloy powder was tested by XRD, and the results are shown in Figure 1. The surface state and microstructure of the alloy powder were observed by SEM and TEM, and the results are shown in Figures 2 and 3. The gaseous hydrogen storage properties such as hydrogen storage capacity and hydrogen absorption and desorption rate of the alloy powder were tested by automatic Sieverts equipment. The results are shown in Table 1.

Example 3

The alloy composition is La _1.8 Y _0.2 Mg ₁₆ Ni+3wt.% TiF ₃ . The as-cast La _1.8 Y _0.2 Mg ₁₆ Ni alloy was prepared according to the method of Example 1, and ball-milled for 10 hours according to the ball-milling procedure of Example 1. After 10 hours of ball milling, 0.15 g of TiF ₃ nanoparticles were added to 4 ball milling jars respectively, and then the ball milling process was carried out for 5 hours according to the ball milling procedure of Example 1. After the ball milling, the ball milling jar was opened to obtain a La _1.8 Y _0.2 Mg ₁₆ Ni+3wt.% TiF ₃ alloy sample.

The phase composition of the alloy powder was tested by XRD, and the results are shown in Figure 1. The surface state and microstructure of the alloy powders were observed by SEM and TEM. The gaseous hydrogen storage properties such as hydrogen storage capacity and hydrogen absorption and desorption rate of the alloy powder were tested by automatic Sieverts equipment. The results are shown in Table 1.

Example 4

The alloy composition is La _1.7 Y _0.3 Mg ₁₆ Ni+5wt.% TiF ₃ . The as-cast La _1.7 Y _0.3 Mg ₁₆ Ni alloy was prepared according to the method of Example 2, and ball-milled for 10 hours according to the ball-milling procedure of Example 2. After 10 hours of ball milling, 0.25 g of TiF ₃ nanoparticles were added to 4 ball milling jars respectively, and then the ball milling process was carried out for 5 hours according to the ball milling procedure of Example 2. After the ball milling, the ball milling jar was opened to obtain a La _1.7 Y _0.3 Mg ₁₆ Ni+5wt.% TiF ₃ alloy sample.

The phase composition of the alloy powder was tested by XRD, and the results are shown in Figure 1. The surface state and microstructure of the alloy powders were observed by SEM and TEM. The gaseous hydrogen storage properties such as hydrogen storage capacity and hydrogen absorption and desorption rate of the alloy powder were tested by automatic Sieverts equipment. The results are shown in Table 1.

Example 5

The alloy composition is La _1.8 Y _0.2 Mg ₁₆ Ni+7wt.% TiF ₃ . The as-cast La _1.8 Y _0.2 Mg ₁₆ Ni alloy was prepared according to the method of Example 1, and ball-milled for 10 hours according to the ball-milling procedure of Example 1. After 10 hours of ball milling, 0.35 g of TiF ₃ nanoparticles were added to 4 ball milling jars respectively, and then the ball milling process was carried out for 5 hours according to the ball milling procedure of Example 1. After the ball milling, the ball milling jar was opened to obtain a La _1.8 Y _0.2 Mg ₁₆ Ni+7wt.% TiF ₃ alloy sample.

The phase composition of the alloy powder was tested by XRD, and the results are shown in Figure 1. The surface state and microstructure of the alloy powders were observed by SEM and TEM. The gaseous hydrogen storage properties such as hydrogen storage capacity and hydrogen absorption and desorption rate of the alloy powder were tested by automatic Sieverts equipment. The results are shown in Table 1.

Example 6

The alloy composition is La _1.7 Y _0.3 Mg ₁₆ Ni+10 wt.% TiF ₃ . The as-cast La _1.7 Y _0.3 Mg ₁₆ Ni alloy was prepared according to the method of Example 2, and ball-milled for 10 hours according to the ball-milling procedure of Example 2. After 10 hours of ball milling, 0.50 g of TiF ₃ nanoparticles were added into 4 ball milling jars respectively, and then the ball milling process was carried out for 5 hours according to the ball milling procedure of Example 2. After the ball milling, the ball milling jar was opened to obtain a La _1.7 Y _0.3 Mg ₁₆ Ni+10wt.% TiF ₃ alloy sample.

The phase composition of the alloy powder was tested by XRD, and the results are shown in Figure 1. The surface state and microstructure of the alloy powders were observed by SEM and TEM, and the results are shown in Figures 4 and 5. The gaseous hydrogen storage properties such as hydrogen storage capacity and hydrogen absorption and desorption rate of the alloy powder were tested by automatic Sieverts equipment. The results are shown in Table 1.

Comparative ratio

The alloy composition is La _1.7 Y _0.3 Mg ₁₆ Ni. The as-cast La _1.7 Y _0.3 Mg ₁₆ Ni alloy was prepared according to the method of Example 2. An appropriate amount of as-cast La _1.7 Y _0.3 Mg ₁₆ Ni alloy was selected, and after mechanical crushing, passed through a 300-mesh sieve to obtain as-cast La _1.7 Y _0.3 Mg ₁₆ Ni alloy powder.

The phase composition of the alloy powder was tested by XRD, and the results are shown in Figure 1. The surface state and microstructure of the alloy powder were observed by SEM and TEM, and the results are shown in Figures 6 and 7. The gaseous hydrogen storage properties such as hydrogen storage capacity and hydrogen absorption and desorption rate of the alloy powder were tested by automatic Sieverts equipment. The results are shown in Table 1.

Table 1 Hydrogen Storage Performance of Examples 1 to 6 and Comparative Examples

C₃₆₀(wt.%) t₅₀(min) E_de(kJ/mol) Example 1 4.87 296 70.5 Example 2 4.85 280 70.2 Example 3 4.81 35 69.5 Example 4 4.68 0.4 67.8 Example 5 4.48 0.4 56.6 Example 6 4.21 0.8 67.1 Comparative ratio 4.98 1290 77.4

C ₃₆₀ — hydrogen storage capacity (wt.%) of alloy at 360℃ and initial hydrogen pressure of 1×10 ^-4 MPa;

t ₅₀ - the time it takes for the alloy to reach 80% of the hydrogen storage capacity at 50 ° C and the initial hydrogen pressure of 3 MPa (min);

E _de - the hydrogen desorption activation energy of the alloy (kJ/mol).

The results in Table 1 show that the alloys treated by alloying, surface treatment and adding additives have high hydrogen storage capacity and excellent hydrogen absorption and desorption kinetics. Compared with similar alloys at home and abroad, the alloy of the present invention has lower hydrogen desorption activation energy and faster hydrogen absorption rate while maintaining higher hydrogen storage capacity (≥4.21wt. The improvement of the hydrogen absorption rate of the invention alloy is more obvious.

Although the preferred embodiment of the present invention has been described, it is obvious that those skilled in the art can adopt other embodiments, such as changing technical parameters such as alloy composition, ball milling time, rotational speed, ball-to-material ratio, additive amount, etc., without departing from the present invention. Various deformations and modifications can be made within the scope of the design idea of the invention, and these changes all belong to the protection of the present invention.

Claims (9)

1. A La-Y-Mg-Ni quaternary hydrogen storage alloy with high hydrogen absorption and desorption rates is characterized in that: the hydrogen storage alloy consists of La-Y-Mg-Ni master alloy and additive TiF₃Composition of La-Y-Mg-Ni master alloy_aY_bMg_cNi_dWherein a is 1.5 to 1.9, b is 0.1 to 0.5, c is 15 to 17, and d is 1; additive TiF₃The alloy is nano particles, and the content of the nano particles is 0-10 wt% of the mass of the La-Y-Mg-Ni master alloy; the main phase of the hydrogen storage alloy is La₂Mg₁₇The second phase comprises La₂Ni₃、Mg₂Ni、MgF₂And TiF₂(ii) a Wherein when TiF₃At a content of 0, only La is present in the alloy₂Mg₁₇，La₂Ni₃、Mg₂A Ni phase.

2. The La-Y-Mg-Ni quaternary hydrogen storage alloy with high hydrogen absorption and desorption rates as claimed in claim 1, wherein: wherein a is 1.7-1.8, b is 0.2-0.3, c is 15.5-16.5, and d is 1.

3. The La-Y-Mg-Ni quaternary hydrogen storage alloy with high hydrogen absorption and desorption rates as claimed in claim 1, wherein: the hydrogen storage alloy has an amorphous nanocrystalline structure.

4. The La-Y-Mg-Ni quaternary hydrogen storage alloy with high hydrogen absorption and desorption rates as claimed in claim 1, wherein: the hydrogen storage alloy is prepared by the following method: smelting La-Y-Mg-Ni master alloy in a vacuum induction smelting furnace under the protective atmosphere, mechanically crushing and high-energy ball milling the obtained as-cast alloy, and then adding a proper amount of TiF₃And (4) continuing ball milling the nano particles to obtain the alloy powder with the amorphous nano-crystalline structure.

5. The La-Y-Mg-Ni quaternary hydrogen storage alloy with high hydrogen absorption and desorption rates as claimed in claim 1, wherein: by adjusting TiF₃The hydrogen absorption time required for the hydrogen storage alloy to reach 80 percent of saturated hydrogen absorption amount at 50 ℃ is 0.4-35 minutes, and the hydrogen desorption activation energy of the alloy is 56.6-69.5 kJ/mol.

6. A method for preparing a high hydrogen absorption and desorption rate La-Y-Mg-Ni quaternary hydrogen storage alloy according to claim 1, characterized in that:

the preparation method comprises the following steps:

proportioning: the component La according to the atomic ratio of the master alloy_aY_bMg_cNi_dMixing materials, wherein a is 1.5-1.9, b is 0.1-0.5, c is 15-17, d is 1, and the purity of the raw material is required to be more than or equal to 99.5%;

preparing a master alloy: smelting the prepared raw materials by a vacuum induction smelting furnace, and vacuumizing the furnace to 1 multiplied by 10 before smelting^-3Pa, recharging high-purity helium with the purity of 99.999 percent until the pressure in the furnace reaches 0.04 +/-0.01 MPa, and then starting heating and smelting to obtain molten La_aY_bMg_cNi_dAlloy, keeping the temperature for 10 +/-3 minutes, injecting the molten alloy into a copper mold, and cooling along with a furnace to obtain as-cast La_1.7Y_0.3Mg₁₆A Ni master alloy;

③ high-energy ball milling: subjecting the as-cast mother La_aY_bMg_cNi_dAlloy is crushed to 300 meshes to obtain alloy powder, adding the alloy powder and grinding balls into a planetary ball mill according to the mass ratio of 1:40, introducing argon as protective gas, and then carrying out high-energy ball milling at the rotating speed of 350r/min for 10 +/-1 hours;

fourthly, adding TiF₃: after the alloy powder is ball-milled for 10 +/-1 hours, opening a ball-milling tank, and adding a proper amount of TiF₃And (3) closing the ball milling tank, introducing argon, and continuing ball milling for 5 +/-1 hours to obtain the alloy powder with the amorphous nanocrystalline structure.

7. The method according to claim 6, wherein: in the step I, the actual adding amount of the rare earth and Mg is respectively 5 percent and 8 percent more than the mixture ratio in the chemical formula.

8. The production method according to claim 6, wherein: and step three, stopping the ball mill for t hours every time the ball mill runs for t hours, then reversely running for t hours, stopping the ball mill for t hours, and repeating the steps until the set total ball milling time is reached, wherein t is 0.4-0.6 hour.

9. The production method according to claim 6, wherein: in the fourth step, TiF₃The timing of addition of (b) is when 5. + -. 1 hours of the total ball milling time remains.

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