AB2 TYPE-BASED HYDROGEN STORAGE ALLOYS, METHODS OF PREPARATION AND USES THEREOF

Abstract

The invention relates to metal hydrides for storing hydrogen, in particular AB2 based metal hydrides, methods of production and uses thereof.

Claims

1. A hydrogen storage alloy having an AB2 type crystal structure, its A site contains Ti and Zr, and its B site contains Cr, Mn, Fe, Ni and Re elements, represented by the general Formula (I)
Ti.sub.xZr.sub.yCr.sub.aMn.sub.bFe.sub.cNi.sub.dCu.sub.eV.sub.fRe.sub.g (I) in which x, y, a, b, c and d are molar ratios Re is selected from La and Ce; 0.2?x?0.95; 0.05?y?0.45; 0.001?a?1; 0.3?b?2; 0.01?c?0.6; 0.005?d?1.5; 0?e?0.1; 0?f?0.5; 0.01?g?0.05; a+b+c+d+e+f+g=1.9-2.3.

2. The hydrogen storage alloy according to claim 1, wherein said alloy is selected from the following group:
Ti.sub.0.65Zr.sub.0.35Cr.sub.0.6Mn.sub.1.15Ni.sub.0.1Cu.sub.0.1La.sub.0.05;
Ti.sub.0.2Zr.sub.0.4Cr.sub.0.6Mn.sub.0.3Fe.sub.0.05Ni.sub.0.14La.sub.0.05;
Ti.sub.0.7Zr.sub.0.1Cr.sub.0.9Mn.sub.0.8Fe.sub.0.5Ni.sub.0.05Cu.sub.0.1Ce.sub.0.05;
Ti.sub.0.85Zr.sub.0.15Cr.sub.0.05Mn.sub.1Fe.sub.0.1Ni.sub.0.45V.sub.0.4La.sub.0.05; and
Ti.sub.0.95Zr.sub.0.05Cr.sub.0.2Mn.sub.0.8Fe.sub.0.3Ni.sub.1Ce.sub.0.05.

3. The hydrogen storage alloy according to claim 1, wherein the hydrogen storage alloy has at 25? C. a hydrogen absorption plateau between 10-150 bar and a desorption plateau between 8-140 bar.

4. The hydrogen storage alloy according to claim 1, wherein the hydrogen storage alloy has at 25? C. a hydrogen storage capacity of about 1.45 to about 1.80 wt % (typically from about 1.50 to 1.65 wt %).

5. A method for the preparation of hydrogen storage alloy having an AB2 type crystal structure by rapid melt solidification by spinning roller quenching, wherein said method comprises the steps of: providing a melt of all the metal elements in the proportions as described in claim 1, in a furnace under a controlled inert atmosphere at a pressure from about 30 KPa to about 70 KPa; casting the melt within said furnace onto a spinning roller rolling at a speed from about 1.5 to about 9 m/s where the melt rapidly solidifies and breaks into flakes when entering a cooling unit; leaving the flakes to further cool down to a temperature below 50? C.; and filling the furnace with air and collecting the obtained flakes.

6. The method according to claim 5 wherein the spinning roller is rolling at a constant speed from about 1 to about 9 m/s.

7. The method according to claim 5, wherein the obtained alloy is subjected to a further temperature treatment a temperature between about 850 and 1,150? C. for about 0.5 to about 72 h.

8. An alloy obtainable by a method according to claim 5.

9. A powder of an alloy according to claim 1, wherein the particle size of the alloy is from about 0.5 mm to about 3 mm.

10. A method of storing hydrogen comprising contacting an alloy according to claim 1 with hydrogen.

11. A hydrogen storage system comprising an alloy according to claim 1 or a powder thereof.

12. The method according to claim 6, wherein the spinning roller is a copper roller.

13. The hydrogen storage alloy according to claim 4, wherein the hydrogen storage alloy has at 25? ? C. a hydrogen storage capacity of about 1.50 to about 1.65 wt %.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The invention will now be described with reference to the accompanying drawings, which by way of example illustrate embodiments of the present invention and in which:

[0032] FIG. 1 represents pressurecompositiontemperature (PCT) isotherms of a metal hydride. A: schematic graphical representations of typical AB2 metal hydrides useful for hydrogen storage (U.S. Pat. No. 4,228,145); B: pcT curve of the material described in US 2004/0206424; C: pcT 10 curve of the material described in CN 1789455

[0033] FIG. 2 represents pressurecompositiontemperature (PCT) isotherms of a metal hydride according to the invention as described in Example 2. A: AB2-type alloy suitable for safety large-scale hydrogen storage at relative low pressure; B & C: AB2-type alloy suitable for high pressure hydrogen compression at different temperatures.

[0034] FIG. 3 represents pressurecompositiontemperature (PCT) isotherms of a metal hydride according to the invention (B) as compared to a two-phase alloy described in CN109609791 (A) as described in Example 3 and (C) X-ray diffraction spectrum of the first alloy described in CN109609791 (C1) compared to the alloy of Example 3 (1) and LaNi5 (AB5 structure).

[0035] FIG. 4 is a schematic representation of a method of preparation of an alloy of the invention by rapid melt solidification by spinning roller quenching.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0036] In the present invention, the hydrogen storage alloy has at 25? C. a hydrogen absorption plateau between 10-150 bar and a desorption plateau between 8-145 bar.

[0037] In the present invention, the hydrogen storage alloy has at 20? C. a hydrogen storage capacity of about 1.45 to about 1.80 wt % (typically from about 1.50 to 1.65 wt %).

[0038] According to a particular embodiment, is provided a AB2 type alloy with single phase microstructure.

[0039] According to a particular embodiment, is provided a hydrogen storage alloy according to claim 1, wherein said alloy is selected from the following group:

Ti.sub.0.65Zr.sub.0.35Cr.sub.0.6Mn.sub.1.15Ni.sub.0.1Cu.sub.0.1La.sub.0.05(5);

Ti.sub.0.2Zr.sub.0.4Cr.sub.0.6Mn.sub.0.3Fe.sub.0.05Ni.sub.0.14La.sub.0.05(1);

Ti.sub.0.7Zr.sub.0.1Cr.sub.0.9Mn.sub.0.8Fe.sub.0.5Ni.sub.0.05Cu.sub.0.1Ce.sub.0.05(2);

Ti.sub.0.85Zr.sub.0.15Cr.sub.0.05Mn.sub.1Fe.sub.0.1Ni.sub.0.45V0.4La.sub.0.05(3); and

Ti.sub.0.95Zr.sub.0.05Cr.sub.0.2Mn.sub.0.8Fe.sub.0.3Ni.sub.1Ce.sub.0.05(4).

[0040] A hydrogen storage alloy according to the invention can be prepared by typical methods used for AB2 alloys such as described in CN1602366.

[0041] Typically, for batches up to 300 kg, raw materials of each required metal elements are placed in a water-cooled copper crucible in an Arc melting furnace and the furnace is put under vacuum (e.g. 5*10.sup.?3 Pa (PABS)) and then filled with a controlled atmosphere (e.g. Ar, >99.99%) under a pressure from about 30K Pa to about 70 KPa (e.g. 50 kPa (PABS)). The raw materials are melted and kept at a melting temperature for about 5 to 10 min and then the melted mixture is let solidified and the solidified alloy (ingot) is turned upside down and melted again and the operation is repeated few times (e.g. 3 to 6 times, such as 5 times) in order to achieve an homogeneous composition of the resulting alloy. Once the last cycle is over and the temperature of the solidified alloy is below 50? C., the furnace is put in communication with air and the ingot alloy is collected.

[0042] For batches from 3 to about 1,000 kg, a method for the preparation of hydrogen storage alloy having an AB2 type crystal structure by rapid melt solidification by spinning roller quenching has described herein is advantageously used. In particular, compared with Arc-melting processes, the alloy prepared by this method has a more homogenous composition, stable crystal structure, less phases other than AB5 structure and lower crystal strain (thus with a smaller hysteresis and more flat plateau pressure). The alloy does need to undergo heat-treatment process before usage, while maintain a long cycle life. This method is also suitable for large scale production and remarkably reduces production cost.

[0043] According to a particular embodiment, the metal elements are melted in a furnace initially purged and put under vacuum (e.g. 5*10.sup.?3 Pa (PABS)) and then filled with a controlled inert atmosphere (e.g. Argon or Helium>99.99%)) at a pressure from about 30 KPa to about 70 KPa (e.g. 50 kPa (PABS)).

[0044] According to a further particular embodiment, the metal elements are melted in a Al.sub.2O.sub.3-based crucible placed in the furnace.

[0045] According to a further particular embodiment, the metal elements are melted in a crucible at a temperature from about 1,850 and 2,150? ? C. placed in a furnace.

[0046] According to a further particular embodiment, after all the metals are melted, the temperature is reduced to a temperature between about 1,750 and 1,850? C. and hold for about 5 to 10 min.

[0047] Referring to FIG. 4, the metal mixture is melted in a crucible 1 (e.g. heated by an induction coil 2) placed in the furnace in said controlled atmosphere and then casted onto a spinning roller 3 (e.g. copper roller) rolling at a constant speed where the melt rapidly solidifies and breaks into flakes 4 when entering into a cooling unit (e.g. water-cooled collector).

[0048] According to a further particular embodiment, the melted mixture is casted onto a spinning roller (e.g. copper roller) rolling at a constant speed from about 1 to about 9 m/s where the melt rapidly solidifies and breaks into flakes. The thickness of the flakes will depend on the roller speed, the lower the speed, the thicker the flakes. According to a particular aspect, the thickness of the flakes typically ranges from 0.1-0.6 mm.

[0049] According to a further particular embodiment, the flakes are left to cool down in the furnace at a temperature in a water-cooled chamber.

[0050] The alloy of the invention could be used directly from the obtained flakes or can undergo a heat-treatment below the melting temperature of the alloy, when needed. The heat treatment is applied to further reduce the hysteresis and improve the cycle performance. Typically, a heat treatment is carried out in a furnace under vacuum (e.g. 9*10.sup.?2 Pa (PABS)), wherein the temperature is raised up to about 200? ? C. and hold to this temperature for about 20 min. Before further increasing the temperature of the furnace, it is filled with an inert atmosphere (e.g. pure Argon (>99.99%)) at a pressure from about 30 KPa to about 70 KPa (e.g. to the pressure of 50 KPa (PABS)). The temperature of the furnace is then increased to a temperature between about 850 and 1,150? C. which is hold for about 0.5 to about 72 h. The temperature-treated alloy is then cooled down at a rate of about 5 to about 20 K/min. Once the temperature of the alloy is below 60? C., the furnace is put in communication with air and the alloy is collected.

[0051] According to a further embodiment, is provided a method for the preparation of hydrogen storage alloy having an AB2 type crystal structure by rapid melt solidification by spinning roller quenching, wherein said method further comprises a heat treatment step.

[0052] The alloy according to the invention (heat-treated or not) can be used in the form of a powder. In particular, the obtained alloys are then crunched into a powder by mechanical or jet milling under the inert gas (e.g. N.sub.2 or Ar, Ar preferred). Typically, the particle size of the alloy could be from about 0.5 mm to about 3 mm, depending on the hydrogen storage system it will be used for.

[0053] The alloy powder can be then stored as a powder under vacuum or inert gas (e.g. N.sub.2 or Ar, Ar preferred).

[0054] Alloys powder can be then used in a hydrogen storage system as described in Bellosta von Colbe et al., 2019, supra.

[0055] Examples illustrating the invention will be described hereinafter in a more detailed manner and by reference to the embodiments represented in the Figures.

EXAMPLES

Example 1: Preparation of Alloys According to the Invention

[0056] An alloy of the invention was prepared as follows.

[0057] The required amount of the metals is weighted according to the Formula (I) in a total weight of 450 kg and placed in a Al.sub.2O.sub.3-based crucible in an industrial induction melting furnace. The furnace is evacuated until the vacuum reached 5*10.sup.?3 Pa (PABS), then filled with Helium (>99.99%) to the pressure of 50 KPa (PABS). The metals are heated up to 1850? C. and then melted. After all metals are melted, the temperature was reduced to 1,550? C. and held for 10 min. The melt was cast onto a spinning Cu roller, the speed of which was set to be 3 m/s, the thickness of the flake is around 0.3 mm. The solidified flake will be led to a water-cooled chamber for further cool down. The furnace was refilled with air and the flake was taken out when the temperature of the flake drop below 50? C. The alloy could be used without further treatment.

[0058] Various examples of alloys of the invention are presented in Table 1 below together with their hydrogen storage performance.

TABLE-US-00001 TABLE 1 Hydrogen Storage A Side B Side Pressure at room (molar ratio) (molar ratio) temperature Ti Zr Cr Mn Fe Ni Cu V La Ce AB (atm) 1 0.2 0.4 0.6 0.3 0.05 0.14 0 0 0.05 0 1.9 15 2 0.7 0.1 0.9 0.8 0.5 0.05 0.1 0 0 0.05 2 35 3 0.85 0.15 0.05 1 0.1 0.45 0 0.4 0.05 0 2.05 73 4 0.95 0.05 0.2 0.8 0.3 1 0 0 0 0.05 2.3 120

Example 2: Hydrogen Storage Capacity of Alloys of the Invention

[0059] The H.sub.2 storage performance of the alloy prepared under Example 1 has been tested as follows. 3 g of alloy ingot/flake was broken into powder (size <100 mesh) and loaded into a stainless cylindrical sample chamber. The alloy was charged with constant 5 MPa of hydrogen pressure for 2 hours. After that the sample was evacuated for 30 min. The charging-evacuation step was repeated at least 3 times, in order to fully activate the alloy.

[0060] A fully-automatic, and computer-controlled volumetric apparatus (known as Sievert's apparatus, or PCT apparatus) will be used to measure the amount of hydrogen absorbed by the alloy at 25? C. in water bath.

[0061] As can be seen under FIG. 2, the alloys of the invention have a much higher and wider desorption plateau than the conventional AB2 alloys. The AB2 alloy used for large-scale hydrogen storage as shown in FIG. 2A shows a suitable plateau pressure at room temperature. The hysteresis and the slope of the plateau of both the charging and discharging are both much smaller than the conventional AB2 alloys. The PCT curves for compression at different temperatures (B and C) show that the pressure increases fast with an increase of temperature and the hysteresis remain small at high pressure output.

Example 3: Activation Ability of Single-Phase Alloy of the Invention

[0062] The ability of the alloy of the invention Ti.sub.0.65Zr.sub.0.35Cr.sub.0.6Mn.sub.1.15Ni.sub.0.1Cu.sub.0.1 La.sub.0.05 (5) to be easily activated at moderate hydrogen pressure has been assessed as follows and compared to the two-phase alloy from 1 Example of CN109609791 when x=0.1 (Ti.sub.0.5Zr.sub.0.5Fe.sub.0.2Cr.sub.0.6Mn.sub.0.2La.sub.0.1Ni.sub.0.1Mn.sub.0.05) by comparing the pcT curves for the two alloys as described under Example 2 and the activation times (Time needed to start absorption of H.sub.2). The two-phase nature of the alloy of CN109609791 is shown by X-ray diffraction at room temperature and atmosphere on FIG. 3C, as compared to the above alloy of the invention (5) and LaNi.sub.5 (AB5 structure).

[0063] As can be seen on FIG. 3, the alloys of the invention present both a hysteresis and a slope of plateau of both the charging and discharging much smaller than the two-phase alloy at room temperature.

[0064] Further, as can be seen in Table2 below, the activation time of the alloy of the invention is nearly immediate after exposing the alloy under a pressure of H.sub.2 of 35 bar, while for the comparative alloy, it takes 80s to initiate the absorption at a pressure above 80 bar H.sub.2.

[0065] 10 PCT/EP2022/071620

TABLE-US-00002 TABLE 2 Initial Time needed Hydrogen to start Pressure absorption Alloy (bar) of H.sub.2 (s) Ti.sub.0.65Zr.sub.0.35Cr.sub.0.6Mn.sub.1.15Ni.sub.0.1Cu.sub.0.1La.sub.0.05 35 15 (from the invention) Ti.sub.0.5Zr.sub.0.5Fe.sub.0.2Cr.sub.0.6Mn.sub.0.2La.sub.0.1Ni.sub.0.1Mn.sub.0.05 80 80 Comparative alloy

[0066] Therefore, those data support that the alloys of the invention are more efficient for H.sub.2 storage even at lower pressure of H.sub.2 than the comparative alloy which relies on the presence of a second phase (AB5 alloy) to help to activate the AB2 alloy.