A modified TiFe-based hydrogen storage alloy and its preparation method

Abstract

This invention relates to the field of hydrogen storage technology, and discloses a modified TiFe-based hydrogen storage alloy and its preparation method. The modified TiFe-based hydrogen storage alloy includes a TiFe-based hydrogen storage alloy and a vanadium-iron alloy; the general chemical formula of the TiFe-based hydrogen storage alloy is TiFe. a Cr b Mn 0.09‑b Co c RE d The elements are: 0.73≤a≤0.88, 0≤b≤0.04, 0.02≤c≤0.03, 0.01≤d≤0.05, and RE is at least one of La, Ce, Y, Sm, Nd, and Pr; the mass ratio of the TiFe-based hydrogen storage alloy to the ferrovanadium alloy is 1:(0-0.04). The modified TiFe-based hydrogen storage alloy of this invention can simultaneously achieve good activation performance, high maximum hydrogen storage capacity, high effective hydrogen release capacity, and low plateau tilt coefficient.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage technology, and more specifically, to a modified TiFe-based hydrogen storage alloy and its preparation method. Background Technology

[0002] The development of hydrogen energy encompasses multiple stages, including hydrogen production, storage, transportation, and utilization. Currently, hydrogen storage and transportation account for the highest costs and are a critical link in the development of hydrogen energy. Achieving low-cost, high-efficiency hydrogen storage can effectively promote the development of the hydrogen energy industry and accelerate hydrogen utilization.

[0003] Alloy hydrogen storage, a widely developed solid-state hydrogen storage method in recent years, boasts high volumetric hydrogen storage density and safety, making it highly suitable for large-scale hydrogen storage. Currently, alloy hydrogen storage materials have been developed in various forms, including AB-type, AB2-type, AB5-type, V-based solid solutions, and Mg-based alloys. AB2-type alloys have a hydrogen storage capacity of approximately 2.0 wt.%, but suffer from activation difficulties and are flammable after use. AB5-type alloys are relatively mature and already in use, but their hydrogen storage capacity is low, only around 1.4 wt.%. V-based solid solutions have a hydrogen storage capacity exceeding 3.0 wt.%, but the application of V incurs high costs and poor cycle stability. Mg-based materials have hydrogen storage capacities exceeding 7.0 wt.%, but their dehydrogenation temperatures are generally above 300℃, limiting their practical application. AB-type hydrogen storage alloys, due to their high hydrogen storage capacity (up to 1.86 wt.%), low cost, and dehydrogenation temperatures generally below 300℃, are considered a very promising hydrogen storage material with the potential for large-scale development and application. TiFe-based hydrogen storage alloys are a type AB hydrogen storage alloy, characterized by high hydrogen storage capacity, low cost, and dehydrogenation temperatures generally below 300℃. However, they suffer from activation difficulties, specifically room temperature activation. Current technologies for improving the activation performance of TiFe-based hydrogen storage alloys struggle to simultaneously achieve high maximum hydrogen storage capacity, high effective hydrogen release capacity, and low plateau tilt coefficient, leading to a decline in the overall performance of TiFe-based hydrogen storage alloys and hindering their widespread application.

[0004] Therefore, it is of great significance to develop a modified TiFe-based hydrogen storage alloy to simultaneously improve the activation performance, maximum hydrogen storage capacity, and effective hydrogen release capacity of TiFe-based hydrogen storage alloys, as well as reduce the plateau tilt coefficient of TiFe-based hydrogen storage alloys. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies in simultaneously improving the activation performance of TiFe-based hydrogen storage alloys while maintaining high maximum hydrogen storage capacity, high effective hydrogen release capacity, and low plateau tilt coefficient, and to provide a modified TiFe-based hydrogen storage alloy and its preparation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a modified TiFe-based hydrogen storage alloy, comprising a TiFe-based hydrogen storage alloy and a ferrovanadium alloy (FeV80); the general chemical formula of the TiFe-based hydrogen storage alloy is TiFe. a Cr b Mn 0.09-b Co c RE d Wherein, 0.73≤a≤0.88, 0≤b≤0.04, 0.02≤c≤0.03, 0.01≤d≤0.05, and RE is at least one of La, Ce, Y, Sm, Nd and Pr; the mass ratio of the TiFe-based hydrogen storage alloy to the ferrovanadium alloy is 1:(0-0.04).

[0008] In the modified TiFe-based hydrogen storage alloy of this invention, the TiFe-based hydrogen storage alloy (TiFe a Cr b Mn 0.09-b Co c RE d Doping with specific amounts of Mn, Co, and RE elements can optimize the microstructure or crystal structure of modified TiFe-based hydrogen storage alloys, adjust the lattice parameters of the modified TiFe alloys, regulate the hydrogen absorption and desorption plateau windows of the modified TiFe-based hydrogen storage alloys, optimize the diffusion channels of hydrogen atoms, and reduce the stress and defects of the modified TiFe-based hydrogen storage alloys during the hydrogen absorption and desorption process. This simultaneously improves the activation performance, maximum hydrogen storage capacity, and effective hydrogen desorption capacity of the modified TiFe-based hydrogen storage alloys, as well as reduces the plateau tilt coefficient of the modified TiFe-based hydrogen storage alloys.

[0009] In the modified TiFe-based hydrogen storage alloy of this invention, when an appropriate amount of Cr is used to replace Mn, the microstructure or crystal structure of the modified TiFe-based hydrogen storage alloy can be further optimized, the lattice parameters of the modified TiFe alloy can be adjusted, and the hydrogen absorption and desorption plateau window of the modified TiFe-based hydrogen storage alloy can be controlled. At the same time, the diffusion channels of hydrogen atoms can be further optimized, thereby further improving the activation performance and maximum hydrogen storage capacity of the modified TiFe-based hydrogen storage alloy.

[0010] In the modified TiFe-based hydrogen storage alloy of this invention, when an appropriate amount of ferrovanadium alloy (FeV80) is used, the microstructure or crystal structure of the modified TiFe-based hydrogen storage alloy can be further optimized, the lattice parameters of the modified TiFe alloy can be adjusted, and the hydrogen absorption and desorption plateau window of the modified TiFe-based hydrogen storage alloy can be controlled. At the same time, the diffusion channels of hydrogen atoms can be further optimized, and the stress and defects of the modified TiFe-based hydrogen storage alloy during the hydrogen absorption and desorption process can be further reduced. Thus, the activation performance, maximum hydrogen storage capacity and effective hydrogen desorption capacity of the modified TiFe-based hydrogen storage alloy can be further improved, and the plateau tilt coefficient of the modified TiFe-based hydrogen storage alloy can be reduced.

[0011] In addition, since ferrovanadium alloy (FeV80) itself contains unavoidable impurities, when an excessive amount of ferrovanadium alloy (FeV80) is used, the modified TiFe-based hydrogen storage alloy will introduce more impurities, resulting in a decrease in the activation performance, maximum hydrogen storage capacity and effective hydrogen release capacity of the modified TiFe-based hydrogen storage alloy, and an increase in the plateau tilt coefficient.

[0012] Preferably, 'a' is a value within a range of one or any two of the following: 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, and 0.88.

[0013] More preferably, 0.82≤a≤0.88.

[0014] Preferably, b is a value within a range of one of 0, 0.01, 0.02, 0.03, and 0.04, or any two of them.

[0015] More preferably, 0.01≤b≤0.04.

[0016] More preferably, 0.01≤b≤0.02.

[0017] Preferably, c is a value between 0.02, 0.03, or any two of them.

[0018] Preferably, d is a value within a range of one or any two of 0.01, 0.02, 0.03, 0.04, and 0.05.

[0019] More preferably, 0.02≤d≤0.05.

[0020] Preferably, the mass ratio of the TiFe-based hydrogen storage alloy to the ferrovanadium alloy is one of 1:0, 1:0.01, 1:0.02, 1:0.03, 1:0.04 or any combination thereof.

[0021] More preferably, the mass ratio of the TiFe-based hydrogen storage alloy to the vanadium-iron alloy is 1:(0.01-0.04).

[0022] More preferably, the mass ratio of the TiFe-based hydrogen storage alloy to the vanadium-iron alloy is 1:(0.01-0.03).

[0023] Preferably, the mass percentage of V in the ferrovanadium alloy (FeV80) is 79-81%.

[0024] Preferably, the Fe element in the ferrovanadium alloy (FeV80) has a mass percentage content of 14-16%.

[0025] Secondly, the present invention provides a method for preparing a modified TiFe-based hydrogen storage alloy, comprising the following steps:

[0026] The modified TiFe-based hydrogen storage alloy is obtained by mixing metals according to the element ratio of the general chemical formula of TiFe-based hydrogen storage alloy, adding ferrovanadium alloy (FeV80), and performing vacuum arc melting.

[0027] Preferably, the current for vacuum arc melting is 120-150A.

[0028] Preferably, the vacuum arc melting is performed 1-5 times, and the duration of each vacuum arc melting is 3-5 minutes.

[0029] More preferably, the vacuum arc melting is performed 3-5 times.

[0030] Preferably, the vacuum degree of the vacuum arc melting is 400-600 Pa.

[0031] Preferably, the vacuum arc melting is carried out under a protective atmosphere.

[0032] More preferably, the protective atmosphere is at least one of argon and helium.

[0033] Preferably, after vacuum arc melting, the process further includes induction melting in a spinning furnace and then spinning the material onto a copper roller for condensation.

[0034] More preferably, the rotational speed of the copper roller is a value within the range of one or any two of the following: 5m / s, 6m / s, 7m / s, 8m / s, 9m / s, 10m / s, 11m / s, 12m / s, 13m / s, 14m / s, 15m / s, 16m / s, 17m / s, 18m / s, 19m / s, 20m / s, 21m / s, 22m / s, 23m / s, 24m / s, 25m / s, 26m / s, 27m / s, 28m / s, 29m / s, 30m / s, 31m / s, 32m / s, 33m / s, 34m / s, 35m / s, 36m / s, 37m / s, 38m / s, 39m / s, and 40m / s.

[0035] More preferably, the rotational speed of the copper roller is 5-40 m / s, specifically 15-25 m / s.

[0036] In this invention, the cooling rate of the smelted alloy can be controlled by adjusting the rotation speed of the copper roller, which can further increase the number of grain boundaries in the modified TiFe-based hydrogen storage alloy, better suppress the generation of amorphous phases, and further improve the internal uniformity of the modified TiFe-based hydrogen storage alloy. This, in turn, further improves the activation performance, maximum hydrogen storage capacity, and effective hydrogen release capacity of the modified TiFe-based hydrogen storage alloy, and reduces the plateau tilt coefficient of the modified TiFe-based hydrogen storage alloy.

[0037] More preferably, the current for induction melting is 20-25A.

[0038] More preferably, the induction melting time is 1-3 minutes.

[0039] More preferably, the vacuum degree of the induction melting is 400-600 Pa.

[0040] More preferably, the induction melting is carried out under a protective atmosphere.

[0041] More preferably, the protective atmosphere is at least one of argon and helium.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0043] In the modified TiFe-based hydrogen storage alloy of this invention, the TiFe-based hydrogen storage alloy (TiFe a Cr b Mn 0.09-b Co c RE dDoping with specific amounts of Mn, Co, and RE elements can optimize the microstructure or crystal structure of modified TiFe-based hydrogen storage alloys, adjust the lattice parameters of the modified TiFe alloys, regulate the hydrogen absorption and desorption plateau windows of the modified TiFe-based hydrogen storage alloys, optimize the diffusion channels of hydrogen atoms, and reduce the stress and defects of the modified TiFe-based hydrogen storage alloys during the hydrogen absorption and desorption process. This simultaneously improves the activation performance, maximum hydrogen storage capacity, and effective hydrogen desorption capacity of the modified TiFe-based hydrogen storage alloys, as well as reduces the plateau tilt coefficient of the modified TiFe-based hydrogen storage alloys.

[0044] In the modified TiFe-based hydrogen storage alloy of this invention, when an appropriate amount of Cr is used to replace Mn, the microstructure or crystal structure of the modified TiFe-based hydrogen storage alloy can be further optimized, the lattice parameters of the modified TiFe alloy can be adjusted, and the hydrogen absorption and desorption plateau window of the modified TiFe-based hydrogen storage alloy can be controlled. At the same time, the diffusion channels of hydrogen atoms can be further optimized, thereby further improving the activation performance and maximum hydrogen storage capacity of the modified TiFe-based hydrogen storage alloy.

[0045] In the modified TiFe-based hydrogen storage alloy of this invention, when an appropriate amount of ferrovanadium alloy (FeV80) is used, the microstructure or crystal structure of the modified TiFe-based hydrogen storage alloy can be further optimized, the lattice parameters of the modified TiFe alloy can be adjusted, and the hydrogen absorption and desorption plateau window of the modified TiFe-based hydrogen storage alloy can be controlled. At the same time, the diffusion channels of hydrogen atoms can be further optimized, and the stress and defects of the modified TiFe-based hydrogen storage alloy during the hydrogen absorption and desorption process can be further reduced. Thus, the activation performance, maximum hydrogen storage capacity and effective hydrogen desorption capacity of the modified TiFe-based hydrogen storage alloy can be further improved, and the plateau tilt coefficient of the modified TiFe-based hydrogen storage alloy can be reduced.

[0046] In addition, since ferrovanadium alloy (FeV80) itself contains unavoidable impurities, when an excessive amount of ferrovanadium alloy (FeV80) is used, the modified TiFe-based hydrogen storage alloy will introduce more impurities, resulting in a decrease in the activation performance, maximum hydrogen storage capacity and effective hydrogen release capacity of the modified TiFe-based hydrogen storage alloy, and an increase in the plateau tilt coefficient.

[0047] In this invention, the cooling rate of the smelted alloy can be controlled by adjusting the rotation speed of the copper roller, which can further increase the number of grain boundaries in the modified TiFe-based hydrogen storage alloy, better suppress the generation of amorphous phases, and further improve the internal uniformity of the modified TiFe-based hydrogen storage alloy. This, in turn, further improves the activation performance, maximum hydrogen storage capacity, and effective hydrogen release capacity of the modified TiFe-based hydrogen storage alloy, and reduces the plateau tilt coefficient of the modified TiFe-based hydrogen storage alloy. Attached Figure Description

[0048] Figure 1 This is a SEM image of the modified TiFe-based hydrogen storage alloy from Example 1.

[0049] Figure 2 The figures show the hydrogen absorption curve at 25°C and the hydrogen release curve at 70°C in the PCT curves of the modified TiFe-based hydrogen storage alloy in Example 1. Detailed Implementation

[0050] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0051] The experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market.

[0052] Example 1

[0053] This embodiment provides a modified TiFe-based hydrogen storage alloy, comprising a TiFe-based hydrogen storage alloy and a vanadium-iron alloy (FeV80); the general chemical formula of the TiFe-based hydrogen storage alloy is TiFe. a Cr b Mn 0.09-b Co c La d Wherein, a=0.82, b=0.01, c=0.02, d=0.02; the mass ratio of the TiFe-based hydrogen storage alloy to the ferrovanadium alloy is 1:0.03; the ferrovanadium alloy (FeV80) contains 80.3% V, 15.28% Fe, 2% Si, 1.5% Al, 0.06% C, 0.05% P, 0.06% As, 0.1% Cu, 0.5% Mn, and 0.15% Ni.

[0054] The preparation method of the above-mentioned modified TiFe-based hydrogen storage alloy includes the following steps:

[0055] According to the general chemical formula of TiFe-based hydrogen storage alloys (TiFe 0.82 Cr 0.01 Mn 0.08 Co 0.02 La 0.02The elemental proportions of Ti, Fe, Cr, Mn, Co, and La were mixed. Ferrovanadium alloy (FeV80) was added at a mass ratio of 1:0.03 between the TiFe-based hydrogen storage alloy and the ferrovanadium alloy. Then, 5g of the mixture was subjected to vacuum arc melting four times under conditions of 150A current, 500Pa vacuum, and argon protective atmosphere. Each vacuum arc melting lasted 3 minutes. After vacuum arc melting, the mixture was transferred to a vacuum spinning furnace and induction melted for 1 minute under conditions of 25A current, 500Pa vacuum, and argon protective atmosphere. The melt was then spun onto a copper roller rotating at 20m / s for condensation, yielding the modified TiFe-based hydrogen storage alloy.

[0056] Examples 2-9 and Comparative Examples 1-6

[0057] Examples 2-9 and Comparative Examples 1-6 provide different modified TiFe-based hydrogen storage alloys. The difference between them and Example 1 is that the chemical formula of the TiFe-based hydrogen storage alloy is different, while the rest is the same as Example 1, as shown in the table below:

[0058] Table 1. Chemical formulas of TiFe-based hydrogen storage alloys in Examples 1-9 and Comparative Examples 1-6

[0059]

[0060] Note: In the table above, 'a' refers to the general chemical formula TiFe for TiFe-based hydrogen storage alloys. a Cr b Mn 0.09-b Co c La d The value of 'a' in the equation refers to the general chemical formula of TiFe-based hydrogen storage alloys, where 'b' refers to TiFe. a Cr b Mn 0.09-b Co c La d The value of b in the equation refers to the general chemical formula of TiFe-based hydrogen storage alloys. a Cr b Mn 0.09-b Co c La d The value of 'c' in the equation refers to the general chemical formula of TiFe-based hydrogen storage alloys. a Cr b Mn 0.09- b Co c La d The possible values ​​of d in the equation.

[0061] Examples 10-12 and Comparative Example 7

[0062] Examples 10-12 and Comparative Example 7 provide different modified TiFe-based hydrogen storage alloys. The difference between them and Example 1 is that the mass ratio of TiFe-based hydrogen storage alloy to ferrovanadium alloy is different. All other aspects are the same as in Example 1, as shown in the table below:

[0063] Table 2. Mass ratio of TiFe-based hydrogen storage alloy to ferrovanadium alloy in Examples 1, 10-12 and Comparative Example 7.

[0064]

[0065] Examples 13-16

[0066] Examples 13-16 provide different modified TiFe-based hydrogen storage alloys, which differ from Example 1 in that the rotational speed of the copper roller is different; otherwise, they are the same as Example 1, as shown in the table below:

[0067] Table 3 shows the rotational speeds of the copper rollers in Examples 1 and 13-16.

[0068]

[0069] Example 17

[0070] This embodiment provides a modified TiFe-based hydrogen storage alloy, which differs from Embodiment 1 in that it does not undergo induction melting and is not condensed on a copper roller, as detailed below:

[0071] Modified TiFe-based hydrogen storage alloys, including TiFe-based hydrogen storage alloys and ferrovanadium alloys (FeV80); the general chemical formula of the TiFe-based hydrogen storage alloys is TiFe. a Cr b Mn 0.09-b Co c La d Wherein, a=0.82, b=0.01, c=0.02, d=0.02; the mass ratio of the TiFe-based hydrogen storage alloy to the ferrovanadium alloy is 1:0.03; the ferrovanadium alloy (FeV80) contains 80.3% V, 15.28% Fe, 2% Si, 1.5% Al, 0.06% C, 0.05% P, 0.06% As, 0.1% Cu, 0.5% Mn, and 0.15% Ni.

[0072] The preparation method of modified TiFe-based hydrogen storage alloy includes the following steps:

[0073] According to the general chemical formula of TiFe-based hydrogen storage alloys (TiFe 0.82 Cr 0.01 Mn 0.08 Co 0.02 La 0.02 The elements Ti, Fe, Cr, Mn, Co and La were mixed in a specific ratio. Ferrovanadium alloy (FeV80) was added to the mixture at a mass ratio of 1:0.03 between the TiFe-based hydrogen storage alloy and the ferrovanadium alloy. Then, 5g of the mixture was subjected to vacuum arc melting four times under the conditions of 150A current, 500Pa vacuum and argon protective atmosphere. Each vacuum arc melting lasted for 3 minutes. After completing the vacuum arc melting, the modified TiFe-based hydrogen storage alloy was obtained.

[0074] Example 18

[0075] This embodiment provides a modified TiFe-based hydrogen storage alloy, which differs from Embodiment 1 in that Ce is used instead of La, i.e., the chemical formula of the TiFe-based hydrogen storage alloy is TiFe. 0.82 Cr 0.01 Mn 0.08 Co 0.02 Ce 0.02 Everything else is the same as in Example 1.

[0076] Example 19

[0077] This embodiment provides a modified TiFe-based hydrogen storage alloy, which differs from Example 1 in that Pr is used instead of La, i.e., the chemical formula of the TiFe-based hydrogen storage alloy is TiFe. 0.82 Cr 0.01 Mn 0.08 Co 0.02 Pr 0.02 Everything else is the same as in Example 1.

[0078] Example 20

[0079] This embodiment provides a modified TiFe-based hydrogen storage alloy, which differs from Embodiment 1 in that Nd is used instead of La, i.e., the chemical formula of the TiFe-based hydrogen storage alloy is TiFe. 0.82 Cr 0.01 Mn 0.08 Co 0.02 Nd 0.02 Everything else is the same as in Example 1.

[0080] Performance testing

[0081] The modified TiFe-based hydrogen storage alloys of each embodiment and comparative example were subjected to the following performance tests:

[0082] 1. Maximum hydrogen storage capacity, effective hydrogen release capacity, plateau tilt coefficient, and hydrogen release plateau pressure test:

[0083] The modified TiFe-based hydrogen storage alloy was tested using a PCT tester (based on Sivert's method) of model MH-PCT manufactured by GRINM of China, under the conditions of 25-70℃ and hydrogen pressure (hydrogen pressure) of 0.01-4MPa.

[0084] (1) In the obtained PCT curves, for the hydrogen absorption curve at 25℃, the hydrogen storage capacity corresponding to a hydrogen pressure of 4MPa is the maximum hydrogen storage capacity (wt.%), with a qualified standard of ≥1.8wt.% and an excellent standard of ≥1.95wt.%;

[0085] (2) In the obtained PCT curve, the amount of hydrogen that can be released when the hydrogen pressure (hydrogen pressure) is above 0.1 MPa is the effective hydrogen release (wt.%). The effective hydrogen release (wt.%) = maximum hydrogen storage capacity (wt.%) - the amount of hydrogen storage that cannot be released when the hydrogen pressure (hydrogen pressure) is below 0.1 MPa on the hydrogen release curve at 70℃; the qualified standard for effective hydrogen release (wt.%) is ≥1.40 wt.%, and the excellent standard is ≥1.69 wt.%.

[0086] (3) In the obtained PCT curve, find the first hydrogen absorption plateau (i.e., the first region on the PCT curve where the modified TiFe-based hydrogen storage alloy has a relatively stable pressure and a significant increase in hydrogen content during the hydrogen absorption process). Define P1 as the pressure (hydrogen pressure) corresponding to the hydrogen absorption amount on the right side of the first hydrogen absorption plateau at 25℃ when the hydrogen absorption amount is 1.2wt.% and define P2 as the pressure (hydrogen pressure) corresponding to the hydrogen absorption amount on the left side of the first hydrogen absorption plateau at 25℃ when the hydrogen absorption amount is 0.2wt.%. Calculate the plateau tilt coefficient according to the formula [plateau tilt coefficient = ln(P1 / P2)]. The qualified standard is ≤0.8 and the excellent standard is ≤0.4.

[0087] The smaller the platform tilt coefficient, the smaller the pressure change of the modified TiFe-based hydrogen storage alloy during the hydrogen absorption process, the flatter the hydrogen absorption platform, and the more stable the hydrogen storage performance of the modified TiFe-based hydrogen storage alloy.

[0088] (4) In the obtained PCT curve, find the plateau pressure of the hydrogen release curve at 70℃ and record it as the hydrogen release plateau pressure, unit: MPa;

[0089] The smaller the hydrogen release plateau pressure, the lower the external pressure required for the modified TiFe-based hydrogen storage alloy to release hydrogen, meaning that the modified TiFe-based hydrogen storage alloy can release hydrogen at a lower pressure.

[0090] 2. Activation performance test:

[0091] Using a PCT tester (model MH-PCT, based on Sivert's method) manufactured by GRINM Advanced Technology & Research Institute Co., Ltd., hydrogen gas at a pressure of 4 MPa was continuously introduced at 25°C to activate the modified TiFe-based hydrogen storage alloy. The hydrogen storage capacity of the modified TiFe-based hydrogen storage alloy after 10 hours of continuous hydrogen introduction was recorded as Q1. The maximum hydrogen storage capacity when the modified TiFe-based hydrogen storage alloy was fully activated (i.e., the hydrogen storage capacity of the modified TiFe-based hydrogen storage alloy no longer increased) was recorded as Q2. The Q value was calculated according to the formula [Q=(Q1 / Q2)×100%]. The Q value was used to characterize the activation performance of the modified TiFe-based hydrogen storage alloy. The larger the Q value, the easier it is for the modified TiFe-based hydrogen storage alloy to be activated at room temperature (25°C), that is, the stronger the activation performance of the modified TiFe-based hydrogen storage alloy.

[0092] The experimental results are shown in the table below:

[0093] Table 4 Performance test results of each embodiment and comparative example

[0094]

[0095]

[0096] Figure 1 This is a SEM image of the modified TiFe-based hydrogen storage alloy from Example 1.

[0097] Figure 2 The figures show the hydrogen absorption curve at 25°C and the hydrogen release curve at 70°C in the PCT curves of the modified TiFe-based hydrogen storage alloy in Example 1.

[0098] From Table 4 and Figure 1-2 It is known that the modified TiFe-based hydrogen storage alloy of the present invention can simultaneously achieve good activation performance, high maximum hydrogen storage capacity, high effective hydrogen release capacity and low plateau tilt coefficient.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a modified TiFe-based hydrogen storage alloy, characterized in that, Includes the following steps: Mix metals according to the element ratio of the general chemical formula of TiFe-based hydrogen storage alloy, add ferrovanadium alloy, perform vacuum arc melting, transfer to a strip spinning furnace for induction melting, and spin onto a copper roller for condensation to obtain the modified TiFe-based hydrogen storage alloy. The general chemical formula of the TiFe-based hydrogen storage alloy is TiFe. a Cr b Mn 0.09-b Co c RE d Wherein, 0.73≤a≤0.88, 0≤b≤0.04, 0.02≤c≤0.03, 0.01≤d≤0.05, and RE is at least one of La, Ce, Y, Sm, Nd and Pr; the mass ratio of the TiFe-based hydrogen storage alloy to the vanadium-iron alloy is 1:(0.01-0.04).

2. The preparation method of the modified TiFe-based hydrogen storage alloy as described in claim 1, characterized in that, include: 0.82≤a≤0.88； And / or, 0.01≤b≤0.04； And / or, 0.02≤d≤0.05。 3. The preparation method of the modified TiFe-based hydrogen storage alloy as described in claim 1, characterized in that, The mass ratio of the TiFe-based hydrogen storage alloy to the ferrovanadium alloy is 1:(0.01-0.03).

4. The preparation method of the modified TiFe-based hydrogen storage alloy as described in claim 1, characterized in that, include: The vanadium-iron alloy has a V element content of 79-81% by mass. And / or, The Fe element in the vanadium-iron alloy has a mass percentage content of 14-16%.

5. The method for preparing the modified TiFe-based hydrogen storage alloy as described in claim 1, characterized in that, The rotational speed of the copper roller is 5-40 m / s.

6. The method for preparing the modified TiFe-based hydrogen storage alloy as described in claim 5, characterized in that, The rotational speed of the copper roller is 15-25 m / s.

7. The preparation method of the modified TiFe-based hydrogen storage alloy as described in claim 1, characterized in that, include: The current for induction melting is 20-25A; And / or, The vacuum degree of the induction melting is 400-600 Pa; And / or, The induction melting is carried out under a protective atmosphere.

8. The method for preparing the modified TiFe-based hydrogen storage alloy as described in claim 1, characterized in that, include: The current for the vacuum arc melting is 120-150A; And / or, The vacuum arc melting is performed 1-5 times, and each vacuum arc melting takes 3-5 minutes. And / or, The vacuum degree of the vacuum arc melting is 400-600 Pa; And / or, The vacuum arc melting is carried out under a protective atmosphere.

9. A modified TiFe-based hydrogen storage alloy, characterized in that, It is prepared by any of the preparation methods described in claims 1-8.

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