CN116162837A - Vanadium-free hydrogen storage alloy and preparation method thereof - Google Patents

Abstract

The invention provides a vanadium-free hydrogen storage alloy and a preparation method thereof, wherein the preparation method comprises the following steps: (1) Mixing and smelting metal Ti, metal Cr and metal M to obtain an as-cast alloy; (2) The cast alloy obtained in the step (1) is subjected to melt rapid quenching to obtain the vanadium-free hydrogen storage alloy; the molar ratio of the metal Ti to the metal Cr to the metal M in the step (1) is (4-5): 5-6): 0.1-0.5; the metal M in the step (1) comprises any one or a combination of at least two of Mo, nb or W. According to the invention, phase regulation and control are realized through melt rapid quenching, so that the vanadium-free hydrogen storage alloy with a BCC structure is obtained, the raw material composition is optimally designed, and the capacity and the hydrogen absorption and desorption performance of the obtained vanadium-free hydrogen storage alloy are improved; the preparation method is simple, low in cost and easy to popularize.

Description

A kind of vanadium-free hydrogen storage alloy and preparation method thereof

technical field

The invention belongs to the field of alloy technology preparation, and relates to a hydrogen storage alloy and a preparation method thereof, in particular to a vanadium-free hydrogen storage alloy and a preparation method thereof.

Background technique

As a renewable clean energy, hydrogen energy has broad application prospects. With the increasing shortage of petrochemical energy and the increasing environmental pollution, hydrogen energy has received more and more attention. Fuel cells using hydrogen as fuel have been gradually applied in fields such as hydrogen-burning vehicles, mopeds, and motorcycles. Its hydrogen source supply system, that is, the storage and delivery of hydrogen, is one of the bottlenecks restricting the further application of hydrogen energy at present, and how to properly solve this problem has become a top priority.

Traditional hydrogen storage methods are divided into high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage, and solid-state hydrogen storage. Among them, solid-state hydrogen storage has a high hydrogen storage capacity, does not require high-pressure or heat-insulated containers, and has no risk of explosion. It is an ideal hydrogen storage Way. Solid hydrogen storage materials mainly include hydrogen storage alloys, nanomaterials and graphene materials. Hydrogen storage alloys have attracted much attention due to their mild action conditions. CN102443730B discloses a hydrogen storage alloy, which is a high-entropy alloy and has a general molecular formula of Co _u Fe _v Mn _w Ti _x V _y Zr _z . The hydrogen storage alloy provided by this technical solution is a rare earth-free Alloy materials of elements, with a single C14Laves phase structure, stable structure, high hydrogen absorption/desorption capacity and hydrogen storage capacity at room temperature under normal temperature and pressure working environment, can be widely used in hydrogen storage and heat storage , heat pumping, hydrogen purification and isotope separation, and used in secondary batteries and fuel cells, etc., and will not produce polluting gases that are harmful to the earth. It is a green energy source with great development potential.

CN101532102B discloses a rare earth hydrogen storage alloy, the chemical formula of the rare earth hydrogen storage alloy has the following general formula: Ml _1-x Dy _x (Ni _a Co _b Al _c Mn _d Cu _e Fe _f Sn _g Cr _h Zn _i ), where 0<x<0.3, 2<a<4, 0<b<0.3, 0.2<c<0.4, 0.2<d<0.5, 0<e<0.2, 0<f<0.25, 0<g<0.22 , 0≤h<0.18, 0<i<0.28, Ml is mixed rare earth. This technical solution uses Cu, Cr, Zn, Fe, Sn to replace the Co element in the rare earth hydrogen storage alloy, which can significantly improve the cycle stability of the hydrogen storage alloy, and is comparable to the commercial hydrogen storage alloy MlNi _3.55 Co _0.75 Mn _0.4 Al _0.3 In contrast, the Co content in the hydrogen storage alloy is reduced by more than 60%, which greatly reduces the production cost, but the capacity of the obtained rare earth alloy is small and cannot meet the demand for high capacity, and there is a unit cell volume expansion during the hydrogen absorption and desorption cycle. Big question.

Vanadium is so far the only metal element in the periodic table that can reversibly absorb and desorb hydrogen at normal temperature and pressure. Vanadium has a body-centered cubic (BCC) structure and has a high hydrogen storage capacity. Its theoretical hydrogen storage capacity can reach Up to 3.8wt%, CN1207412C discloses a Ti-V based BCC phase hydrogen storage alloy with high hydrogen storage capacity. The composition of the hydrogen storage alloy is Ti _100-xyz V _x Mn _y M _z , where 15≤x≤50, 5≤y≤30, 5≤z≤30, 50≤x+y+z≤80(x, y , z are atomic percentages). M is at least one or two elements of Cr, Fe, Ni or RE (rare earth). The alloy forms a single BCC solid solution phase or a two-phase structure in which the BCC phase contains a part of the C14Laves phase. The production of the alloy includes an annealing process, the condition of which is: annealing at 800-1500°C for 0.5-50h. The maximum hydrogen content of the alloy is 3.8-4.2%, and the hydrogen release capacity below 100°C is 2.5-3%. However, vanadium has the disadvantage of being expensive as a raw material for hydrogen storage alloys.

On the basis that the vanadium-based hydrogen storage alloy has a BCC structure, the present invention proposes a vanadium-free hydrogen storage alloy with a BCC structure, and optimizes the hydrogen storage performance of the obtained hydrogen storage alloy through lattice control and melt rapid quenching, and reduces Hydrogen storage cost of the alloy.

Contents of the invention

Aiming at the deficiencies in the prior art, the object of the present invention is to provide a vanadium-free hydrogen storage alloy and its preparation method, through the optimized design of raw material components and phase control, the capacity and hydrogen storage performance of the hydrogen storage alloy can be improved, and the hydrogen storage performance can be reduced. Cost of production.

For reaching this purpose, the present invention adopts following technical scheme:

In a first aspect, the present invention provides a method for preparing a vanadium-free hydrogen storage alloy, the preparation method comprising the following steps:

(1) After metal Ti, metal Cr and metal M are mixed and smelted, an as-cast alloy is obtained;

(2) The as-cast alloy obtained in step (1) is subjected to melt rapid quenching to obtain the vanadium-free hydrogen storage alloy;

The molar ratio of metal Ti, metal Cr and metal M described in step (1) is (4-5):(5-6):(0.1-0.5);

The metal M in step (1) includes any one or a combination of at least two of Mo, Nb or W.

The preparation method provided by the present invention has optimized the design of the raw material composition, and realizes phase control through melt rapid quenching, which improves the capacity and hydrogen absorption and desorption performance of the obtained vanadium-free hydrogen storage alloy; the preparation method is simple and low in cost , easy to promote.

The metal Ti in the present invention is a simple substance of Ti; the metal Cr is a simple substance of Cr; and the metal M is a simple substance of M.

The mol ratio of metal Ti, metal Cr and metal M described in step (1) in the present invention is (4-5):(5-6):(0.1-0.5), for example can be 4:5:0.1,4.5: 5.5:0.3, 5:6:0.5, 4:6:0.1 or 5:5:0.1, but not limited to the listed values, other unlisted values within the value range are also applicable. In the process of preparing the hydrogen storage alloy, the present invention improves the hydrogen storage performance of the obtained hydrogen storage alloy by optimizing the raw material components of metal Ti, metal Cr and metal M.

In the raw material components of the present invention, when the content of metal Ti is too low, the lattice constant of the obtained vanadium-free hydrogen storage alloy is too small, which reduces the hydrogen absorption capacity and affects the hydrogen storage performance; when the content of Ti is too high, the obtained The lattice constant of the hydrogen storage alloy is too large, and the hydrogen absorption capacity is slightly increased, but the plateau pressure is low, resulting in a decrease in the effective hydrogen release capacity, which will also affect the hydrogen storage performance.

The metal M in step (1) includes any one or a combination of at least two of Mo, Nb or W. Typical but non-limiting combinations include the combination of Mo and Nb, the combination of Mo and W, the combination of Nb and W combination, or a combination of Mo, Nb and W.

Exemplarily, when M is Mo, if the content of Mo is too low, the hydrogen absorption and desorption platform pressure of the vanadium-free hydrogen storage alloy will be too low to effectively desorb hydrogen; if the content of Mo is too high, due to the high melting point of Mo, Compared with Ti and Cr, there is a large difference in melting point. Excessive Mo content will cause greater stress in the melt quenching process of the vanadium-free hydrogen storage alloy, resulting in a larger slope of the hydrogen absorption and desorption platform, reducing the hydrogen absorption. quantity.

When M is Nb, if the content of Nb is too low, the vanadium-free hydrogen storage alloy cannot form a single BCC phase, resulting in the reduction of the theoretical hydrogen storage sites; if the content of Nb is too high, the resulting vanadium-free hydrogen storage alloy has a If the lattice constant is too high, the hydrogen absorption and desorption platform will be reduced, thereby reducing the effective hydrogen release capacity and affecting the hydrogen storage performance.

When M is W, if the content of W is too low, the vanadium-free hydrogen storage alloy cannot form a single BCC phase, resulting in the reduction of the theoretical hydrogen storage sites; if the content of W is too high, due to the high melting point of W, It will make the composition distribution uneven and form intermetallic compounds, resulting in the reduction of hydrogen storage sites.

Preferably, the melting current in step (1) is 100-200A, such as 100A, 120A, 140A, 160A, 180A or 200A, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable .

Preferably, the number of smelting in step (1) is 3-5 times, such as 3 times, 4 times or 5 times.

Preferably, the melting time in step (1) is 10-25s/time, such as 10s/time, 12s/time, 14s/time, 16s/time, 18s/time or 20s/time, but not limited to Listed values, other unlisted values within the range of values also apply.

Preferably, the crystal structure of the as-cast alloy obtained in step (1) is Laves phase.

Preferably, the lattice constant a of the as-cast alloy obtained in step (1) is 0.68-0.7nm, such as 0.68nm, 0.69nm or 0.7nm, but not limited to the listed values, and other unlisted values within the numerical range The same applies.

Preferably, the induction melting power of the rapid quenching of the melt in step (2) is 10-20kW, for example, it can be 10kW, 12kW, 14kW, 16kW, 18kW or 20kW, but it is not limited to the listed values. The listed values also apply.

Preferably, the time for rapid quenching of the melt in step (2) is 3-10min, such as 3min, 4min, 5min, 6min, 7min, 8min, 9min or 10min, but not limited to the listed values, within the range of Other values not listed also apply.

Preferably, the speed of rapid quenching of the melt in step (2) is 5-20m/s, such as 5m/s, 8m/s, 10m/s, 13m/s, 15m/s, 18m/s or 20m /s, but not limited to the listed values, other unlisted values within the range of values are also applicable.

Preferably, the crystal structure of the vanadium-free hydrogen storage alloy obtained in step (2) is BCC phase.

Preferably, the lattice constant of the vanadium-free hydrogen storage alloy obtained in step (2) is 0.304-0.307nm, such as 0.304nm, 0.305nm, 0.306nm or 0.307nm, but not limited to the listed values, other values within the range Values not listed also apply.

As a preferred technical solution of the preparation method described in the first aspect of the present invention, the preparation method includes the following steps:

(1) After metal Ti, metal Cr and metal M are mixed, smelt 3-5 times under the electric current of 100-200A, the time of smelting is 10-25s/time, obtains the as-cast alloy that crystal structure is Laves phase; Gained The lattice constant a of the as-cast alloy is 0.68-0.7nm;

(2) step (1) gained as-cast alloy carries out melt quick quenching 3-10min under the induction melting power of 10-20kW, and the speed of melt quick quenching is 5-20m/s, obtains crystal structure and is BCC phase-free Vanadium hydrogen storage alloy; the lattice constant a of the obtained vanadium-free hydrogen storage alloy is 0.304-0.307nm;

The molar ratio of metal Ti, metal Cr and metal M described in step (1) is (4-5):(5-6):(0.1-0.5);

The metal M in step (1) includes any one or a combination of at least two of Mo, Nb or W.

In a second aspect, the present invention provides a vanadium-free hydrogen storage alloy obtained by the preparation method described in the first aspect.

Compared with prior art, the beneficial effect of the present invention is:

The metal M in the present invention is Mo, Nb or W with a BCC structure, and the phase control is realized by rapid quenching of the melt, thereby obtaining a vanadium-free hydrogen storage alloy with a BCC structure, and an optimized design is carried out on the raw material composition to improve The capacity and hydrogen absorption and desorption properties of the obtained vanadium-free hydrogen storage alloy; the preparation method is simple, low in cost and easy to popularize.

Detailed ways

The technical solutions of the present invention will be further described below through specific embodiments.

Example 1

This embodiment provides a method for preparing a vanadium-free hydrogen storage alloy, the preparation method comprising the following steps:

(1) Mix metal Ti, metal Cr and metal M, the molar ratio of metal Ti, metal Cr and metal M is 4.5:5.3:0.2; under the current of 150A, under the vacuum degree of 400Pa, the electric arc furnace is used for smelting 4 times, the time of smelting is 20s/time, and the cast alloy is obtained;

The metal M is Mo;

(2) The as-cast alloy obtained in step (1) was subjected to rapid melt quenching for 4 minutes under the induction melting power of 15 kW, and the speed of melt quenching was 10 m/s to obtain the vanadium-free hydrogen storage alloy.

Example 2

This embodiment provides a method for preparing a vanadium-free hydrogen storage alloy, the preparation method comprising the following steps:

(1) Mix metal Ti, metal Cr and metal M, the molar ratio of metal Ti, metal Cr and metal M is 4:6:0.2, under the current of 100A, under the vacuum degree of 300Pa, use electric arc furnace to melt 3 times, the time of smelting is 25s/time, and the cast alloy is obtained;

The metal M is Nb;

(2) The as-cast alloy obtained in step (1) was subjected to rapid melt quenching for 10 minutes at an induction melting power of 10 kW at a speed of 5 m/s to obtain the vanadium-free hydrogen storage alloy.

Example 3

This embodiment provides a method for preparing a vanadium-free hydrogen storage alloy, the preparation method comprising the following steps:

(1) Mix metal Ti, metal Cr and metal M, the molar ratio of metal Ti, metal Cr and metal M is 5:5:0.1, under the current of 200A, under the vacuum degree of 500Pa, use electric arc furnace to melt 5 times, the time of smelting is 10s/time, and the cast alloy is obtained;

The metal M is W;

(2) The as-cast alloy obtained in step (1) was subjected to rapid melt quenching for 3 minutes under the induction melting power of 20 kW, and the speed of rapid melt quenching was 20 m/s to obtain the vanadium-free hydrogen storage alloy.

Example 4

This embodiment provides a method for preparing a vanadium-free hydrogen storage alloy. In the preparation method, except that the induction melting power of the melt quenching described in step (2) is 18kW, and the melt quenching time is 3min, the other All the same as in Example 1.

Example 5

This embodiment provides a method for preparing a vanadium-free hydrogen storage alloy. In the preparation method, except that the induction melting power of the melt quenching described in step (2) is 20kW, and the melt quenching speed is 15m/s , all the other are identical with embodiment 4.

Comparative example 1

This comparative example provides a preparation method of an as-cast alloy. In the preparation method, except that the as-cast alloy obtained in step (1) does not undergo rapid quenching of the melt, the rest are the same as in Example 1.

Comparative example 2

This comparative example provides a method for preparing a vanadium-free hydrogen storage alloy. In the preparation method, except that the molar ratio of metal Ti, metal Cr and metal M described in step (1) is 6:3.8:0.2, all the others are the same as Example 1 is the same.

Comparative example 3

This comparative example provides a method for preparing a vanadium-free hydrogen storage alloy. In the preparation method, except that the molar ratio of metal Ti, metal Cr and metal M described in step (1) is 3.8:6:0.2, all the others are the same as Example 1 is the same.

Comparative example 4

This comparative example provides a method for preparing a vanadium-free hydrogen storage alloy. In the preparation method, except that the molar ratio of metal Ti, metal Cr and metal M described in step (1) is 4:4:2, all the others are the same as Example 1 is the same.

Comparative example 5

This comparative example provides a method for preparing a vanadium-free hydrogen storage alloy. In the preparation method, except that the molar ratio of metal Ti, metal Cr and metal M described in step (1) is 4.5:5.45:0.05, all the others are the same as Example 1 is the same.

Performance Testing

The vanadium-free hydrogen storage alloy obtained in Examples 1-5 and Comparative Example 2-5 and the as-cast alloy obtained in Comparative Example 1 were tested for performance, and the properties of the as-cast alloy and the vanadium-free hydrogen storage alloy obtained in the preparation process were tested by XRD. _phase , and tested the maximum hydrogen absorption capacity, For effective hydrogen release capacity and platform pressure, refer to the national standard GB/T 33291-2016 for specific test methods.

The results are shown in Table 1.

Table 1

It can be seen from Examples 1-5 that in the preparation method provided by the present invention, the method of rapid quenching of the melt is used to realize the phase transformation of the crystal structure from Laves to BCC, and the obtained vanadium-free hydrogen storage alloy has excellent hydrogen storage performance. The maximum hydrogen absorption is as high as 3.6wt%, the effective hydrogen release is as high as 2.3wt%, and the platform pressure is around 0.2MPa.

From the comparison of Comparative Example 1 and Example 1, it can be seen that the hydrogen storage performance of the as-cast alloy without melt quenching is slightly lower than that of the vanadium-free hydrogen storage alloy, the maximum hydrogen absorption is only 1.8wt%, and the effective hydrogen release is only 0.7wt%, and the hydrogen absorption and desorption platform is inclined, and there is no platform pressure.

From the comparison of Comparative Example 2, Comparative Example 3 and Example 1, it can be seen that in the process of preparing the hydrogen storage alloy, the present invention makes step (1) The phase transformation of the obtained as-cast alloy occurs, and the hydrogen storage performance of the obtained hydrogen storage alloy is improved. When the content of Ti is too high, the lattice constant of the obtained hydrogen storage alloy is greater than 0.307nm, and the hydrogen absorption capacity is slightly increased, but the plateau pressure is low, resulting in a decrease in the effective hydrogen release capacity, which will also affect the hydrogen storage performance; when Ti When the content is too low, the lattice constant of the obtained vanadium-free hydrogen storage alloy is less than 0.304nm, which reduces the hydrogen absorption capacity, and cannot form a single BCC phase, which affects the hydrogen storage performance.

From the comparison of Comparative Examples 4-5 and Example 1, it can be seen that in the process of preparing the hydrogen storage alloy, the present invention optimizes the raw material components of metal Ti, metal Cr and metal M, so that the casting obtained in step (1) The phase transformation of the state alloy occurs, and the hydrogen storage performance of the obtained hydrogen storage alloy is improved. When the content of Mo is too high, due to the high melting point of Mo, there is a large difference in melting point from Ti and Cr. If the content of Mo is too high, the vanadium-free hydrogen storage alloy will generate greater stress during the rapid quenching of the melt. As a result, the slope of the hydrogen absorption and desorption platform is relatively large, which reduces the hydrogen absorption capacity; when the Mo content is too low, the hydrogen absorption and desorption platform of the alloy is low and cannot effectively desorb hydrogen.

In summary, the present invention provides a vanadium-free hydrogen storage alloy and a preparation method thereof, wherein the metal element M is Mo, Nb or W with a BCC structure, and the phase control is realized by rapid quenching of the melt, thereby obtaining a non-vanadium hydrogen storage alloy with a BCC structure. The vanadium hydrogen storage alloy is optimized and designed on the composition of raw materials, and the capacity and hydrogen absorption and desorption performance of the obtained vanadium-free hydrogen storage alloy are improved; the preparation method is simple, low in cost, and easy to popularize.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A method for preparing vanadium-free hydrogen storage alloy, which is characterized by comprising the following steps:

(1) Mixing and smelting metal Ti, metal Cr and metal M to obtain an as-cast alloy;

(2) The cast alloy obtained in the step (1) is subjected to melt rapid quenching to obtain the vanadium-free hydrogen storage alloy;

the molar ratio of the metal Ti to the metal Cr to the metal M in the step (1) is (4-5): 5-6): 0.1-0.5;

the metal M in the step (1) comprises any one or a combination of at least two of Mo, nb or W.

2. The method of claim 1, wherein the smelting current in step (1) is 100-200A.

3. The method of claim 1 or 2, wherein the number of times of smelting in step (1) is 3 to 5;

preferably, the smelting in step (1) takes 10-25 s/time.

4. A method according to any one of claims 1 to 3, wherein the as-cast alloy obtained in step (1) has a Laves phase crystal structure;

preferably, the as-cast alloy obtained in step (1) has a lattice constant a of 0.68-0.7nm.

5. The method of any one of claims 1 to 4, wherein the induction melting power of the melt-quench of step (2) is from 10 to 20kW.

6. The method according to any one of claims 1 to 5, wherein the time for rapid melt quenching in step (2) is 3 to 10min.

7. The process according to any one of claims 1 to 6, wherein the melt-quenching in step (2) is carried out at a rate of 5 to 20m/s.

8. The method according to any one of claims 1 to 7, wherein the vanadium-free hydrogen storage alloy obtained in step (2) has a crystal structure of BCC phase;

preferably, the lattice constant a of the vanadium-free hydrogen storage alloy obtained in the step (2) is 0.304-0.307nm.

9. The preparation method according to any one of claims 1 to 8, characterized in that the preparation method comprises the steps of:

(1) After mixing metal Ti, metal Cr and metal M, smelting for 3-5 times under the current of 100-200A for 10-25 s/time to obtain as-cast alloy with a Laves phase crystal structure; the lattice constant a of the obtained as-cast alloy is 0.68-0.7nm;

(2) Carrying out melt rapid quenching on the as-cast alloy obtained in the step (1) for 3-10min under the induction smelting power of 10-20kW, wherein the speed of melt rapid quenching is 5-20m/s, and obtaining the vanadium-free hydrogen storage alloy with a BCC phase crystal structure; the lattice constant a of the obtained vanadium-free hydrogen storage alloy is 0.304-0.307nm;

the molar ratio of the metal Ti to the metal Cr to the metal M in the step (1) is (4-5): 5-6): 0.1-0.5;

the metal M in the step (1) comprises any one or a combination of at least two of Mo, nb or W.

10. A vanadium-free hydrogen storage alloy, characterized in that the vanadium-free hydrogen storage alloy is obtained by the production method according to any one of claims 1 to 9.