NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy and preparation method thereof

Abstract

The invention discloses a NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy and a preparation method thereof. The chemical formula of the AB2 type hydrogen storage alloy is TiaZr (1-a-b) YbMnxCr (1.8-x) Fe (0.2), and the mass ratio of the AB2 type hydrogen storage alloy to NH4H2PO4 to CaCO3 is 98: 1: 1; the preparation method comprises the following steps: 1, selecting a metal elementary substance raw material; 2, performing vacuum arc melting to obtain an alloy ingot; 3, crushing and grinding the alloy cast ingot; and 4, drying the powder with NH4H2PO4 and CaCO3 powder, and then carrying out ball milling and mixing. According to the alloy, by controlling the content of Cr, Mn, Fe and Y elements, the activation performance at the room temperature is improved, the hydrogen absorption rate is increased, the hydrogen storage capacity is increased, NH4H2PO4 and CaCO3 are combined for modification, the spontaneous combustion tendency of hydrogen absorption state powder in air is reduced, and the alloy is suitable for the field of solid hydrogen storage.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid hydrogen storage alloys, and in particular relates to an NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy and a preparation method thereof. Background Art

[0002] Hydrogen energy is considered to be the most promising secondary energy source in the future due to its advantages such as light weight, high energy density and easy conversion with other energy sources. The key to the large-scale application of hydrogen energy is the development of safe, efficient and economical hydrogen storage technology. At present, the main methods of hydrogen energy storage include high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage and solid material hydrogen storage: high-pressure gaseous hydrogen storage has extremely high requirements for hydrogen storage containers, hydrogen cylinders are prone to leakage, and have low safety; low-temperature liquid hydrogen storage requires high energy consumption, and the temperature difference between the inside and outside of the hydrogen storage container is large, which places stringent requirements on the material selection and preparation of the hydrogen storage container; solid-state hydrogen storage mainly achieves the purpose of storing hydrogen by adsorbing hydrogen or reacting chemically with hydrogen. Among them, metal hydride solid-state hydrogen storage has certain advantages in the cycle stability of hydrogen absorption and desorption, energy density, and transportation, and is expected to become the most widely used hydrogen storage method in the future.

[0003] Commonly used hydrogen storage alloys include titanium, magnesium, vanadium, and rare earth alloys. Rare earth-based hydrogen storage materials have relatively low hydrogen storage capacity and high cost; vanadium-based hydrogen storage materials have high activation temperatures (300°C–400°C), low plateau pressures, and poor cyclic reversibility; and magnesium-based hydrogen storage materials exhibit high hydride stability, with dehydrogenation temperatures generally exceeding 300°C. In contrast, Ti-Mn-based AB2-type hydrogen storage alloys are low cost, simple to prepare, offer mild hydrogen absorption and desorption conditions, and exhibit rapid reaction rates, making them suitable for large-scale applications. However, the major challenges facing Ti-Mn-based hydrogen storage alloys in practical applications include difficulty in room temperature activation, high plateau pressures, significant hysteresis in hydrogen absorption and desorption, and low hydrogen storage capacity. Furthermore, Ti-Mn-based hydrogen storage alloy powders are highly reactive and prone to spontaneous combustion when exposed to air after hydrogen absorption and desorption, posing a serious safety hazard.

[0004] The invention with publication number CN117987676A discloses a Ti-Mn-based hydrogen storage alloy containing the rare earth element Ce and its preparation method. The alloy has a suitable hydrogen absorption and desorption platform pressure and a hydrogen storage capacity of up to 1.97wt.% at room temperature. However, the alloy activation temperature reaches 150°C, which is not conducive to the alloy's application at room temperature. At the same time, the patent does not address the safety issues of the active alloy powder, and there is still a risk of spontaneous combustion in actual applications. The invention with publication number CN115377433A discloses a method for preparing a high-performance AB2-type hydrogen storage alloy. This method mainly uses suspension melting, belt melting, graphene doping and high-energy ball milling to prepare the AB2-type hydrogen storage alloy. The prepared alloy can be activated at room temperature and has a maximum hydrogen absorption capacity of 1.8wt.%. However, the process is complex and energy-intensive, making it unsuitable for mass production. In the invention with publication number CN117265306, a Ti-Mn based hydrogen storage alloy and its preparation method are disclosed. This method mainly uses a manganese-chromium master alloy to prepare the hydrogen storage alloy, which can reduce the loss of volatile elements during smelting and improve the activation performance. However, the maximum hydrogen absorption capacity of the alloy at room temperature is less than 1.8wt.%. In the document "Influence of Ti super-stoichiometry on the hydrogen storage properties of Ti 1+x Cr 1.2 Mn 0.2 Fe 0.6 (x = 0-0.1) alloys for hybrid hydrogen storage application. Journal of Alloys and Compounds, 585 (2014): 307-311”, Chen et al. designed a Ti-Mn based AB2 type hydrogen storage alloy that can be activated at room temperature. However, the room temperature hydrogen absorption rate of the alloy is slow, the hydrogen absorption platform pressure exceeds 8 MPa, and the hydrogen storage capacity is only 1.61 wt.%.

[0005] In summary, currently developed Ti-Mn-based hydrogen storage alloys struggle to balance activation performance, hydrogen storage capacity, hydrogen absorption rate, and hydrogen absorption and desorption plateau pressure. Furthermore, the spontaneous combustion of active alloy powders remains a major technical bottleneck restricting the practical application of Ti-Mn-based hydrogen storage alloys. The development of a Ti-Mn-based hydrogen storage alloy with superior comprehensive performance and its preparation method are urgently needed, as they are of great significance for the future large-scale application of hydrogen energy. Summary of the Invention

[0006] The present invention addresses the shortcomings of the prior art by providing a high-performance AB2-type hydrogen storage alloy modified with NH4H2PO4-CaCO3. By controlling the contents of Cr, Mn, Fe, and Y, this alloy enhances room-temperature activation properties, improves hydrogen absorption and desorption kinetics, accelerates hydrogen absorption rate, and increases hydrogen storage capacity. Combined with NH4H2PO4 and CaCO3 modification, this alloy reduces the tendency of hydrogen-absorbed powders to spontaneously combust in air. This addresses key bottlenecks of prior art Ti-Mn-based hydrogen storage alloys, including difficulty in room-temperature activation, insufficient hydrogen storage capacity, and the tendency of hydrogen-absorbed powders to spontaneously combust in air.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a high-performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3, characterized in that the chemical formula of the AB2 type hydrogen storage alloy is: Ti a Zr 1-a-b Y b Mn x Cr 1.8- x Fe 0.2 , 0.70≤a≤0.90, 0≤b≤0.07, 1.10≤x≤1.25, a, b and x are all atomic ratios, and the mass ratio of AB2 type hydrogen storage alloy to NH4H2PO4 and CaCO3 is 98:1:1.

[0008] The above-mentioned NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy is characterized in that the modified high-performance AB2 type hydrogen storage alloy can absorb hydrogen after the first activation at room temperature, the hydrogen absorption platform pressure does not exceed 2.4 MPa, the hydrogen desorption platform pressure is above 0.4 MPa, the hydrogen storage capacity is above 1.93wt.%, and after the hydrogen absorption and desorption are completed, it is exposed to the air for 72 hours without spontaneous combustion.

[0009] At the same time, the present invention also discloses a method for preparing the above-mentioned NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy, characterized in that the method comprises the following steps: Step 1: According to the chemical formula composition of the AB2-type hydrogen storage alloy in the target product NH4H2PO4-CaCO3-modified high-performance AB2-type hydrogen storage alloy, Ti, Zr, Mn, Cr, Y and Fe metal elements are selected, weighed and cleaned to obtain raw materials; Step 2: vacuum arc melting the raw materials obtained in step 1 to obtain an AB2 type hydrogen storage alloy ingot; Step 3: After removing the oxide scale from the AB2 hydrogen storage alloy ingot obtained in Step 2, the ingot is mechanically crushed and manually ground to obtain AB2 hydrogen storage alloy powder; Step 4: Dry and ball-mill the AB2 type hydrogen storage alloy powder obtained in step 3 with NH4H2PO4 and CaCO3 powder to obtain a NH4H2PO4-CaCO3 modified high performance AB2 type hydrogen storage alloy.

[0010] The above-mentioned method for preparing a high-performance AB2-type hydrogen storage alloy modified by NH4H2PO4-CaCO3 is characterized in that the mass purity of the Ti, Zr, Mn, Cr, Y and Fe metal elements described in step 1 is greater than 99.9%.

[0011] The above-mentioned method for preparing a high-performance AB2-type hydrogen storage alloy modified by NH4H2PO4-CaCO3 is characterized in that, when weighing the Mn metal element in step 1, an additional 5 wt.% Mn burn-out amount needs to be added.

[0012] The above-mentioned method for preparing a high-performance AB2-type hydrogen storage alloy modified with NH4H2PO4-CaCO3 is characterized in that the vacuum arc melting in step 2 is performed at a current of 300A to 400A and the number of melting passes is four. By controlling the vacuum arc melting current, the present invention ensures that all metal elements in the raw materials are fully melted. By controlling the number of melting passes to four, the resulting alloy ingot has a segregation-free microstructure, eliminating the need for additional homogenization annealing.

[0013] The above-mentioned method for preparing a high-performance AB2-type hydrogen storage alloy modified with NH4H2PO4-CaCO3 is characterized in that the particle size of the AB2-type hydrogen storage alloy powder in step 3 is 38µm to 75µm. By controlling the particle size of the AB2-type hydrogen storage alloy powder, the present invention not only increases the contact area between the product powder and hydrogen by refining the powder, but also accelerates the hydrogen absorption rate and increases the hydrogen storage capacity. It also avoids powder oxidation and electrostatic adsorption caused by excessively small product powder particle size.

[0014] The above-mentioned method for preparing a high-performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 is characterized in that the mass purity of the NH4H2PO4 and CaCO3 powders in step 4 is greater than 99.9%, and the size is nanometer-scale.

[0015] The above-mentioned method for preparing a high-performance AB2-type hydrogen storage alloy modified by NH4H2PO4-CaCO3 is characterized in that the drying temperature in step 4 is 80°C, the time is 3 hours, the ball-to-material ratio of the ball mill is 5:1, the rotation speed is 250 rpm, and the mixing time is 0.5 hours.

[0016] Compared with the prior art, the present invention has the following advantages: 1. The high-performance AB2-type hydrogen storage alloy modified by NH4H2PO4-CaCO3 of the present invention is fully activated at room temperature by rationally controlling the contents of Cr, Mn, and Fe in the alloy without affecting the hydrogen storage capacity. By rationally controlling the atomic ratio of the Y element to not exceed 0.07, the Y atoms with larger radii are used to increase the lattice constant of the C14 Laves structure, accelerate hydrogen absorption kinetics, and increase hydrogen storage capacity. On the other hand, the generated Y oxides and Y-rich phases are used as hydrogen diffusion channels or catalytic sites to improve hydrogen absorption / desorption kinetics and avoid Y segregation caused by excessive Y content, which leads to a reduction in the main phase of the C14 structure and is detrimental to hydrogen storage performance.

[0017] 2. The present invention promotes the melting of raw material components by controlling the melting current and melting times of vacuum arc melting, thereby obtaining an alloy ingot with uniform structure and no segregation, omitting the conventional homogenization annealing process. The smelting preparation process is simple and suitable for industrial mass production.

[0018] 3. The present invention controls the particle size of the AB2 type hydrogen storage alloy powder and thus controls the particle size of the product powder, which is beneficial to improving the hydrogen absorption rate of the NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy and increasing the hydrogen storage capacity.

[0019] 4. The present invention adds a small amount of NH4H2PO4 and CaCO3 powder to the AB2 type hydrogen storage alloy powder for modification. When the product NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy powder is exposed to air, CaCO3 will undergo endothermic decomposition, which will reduce the powder temperature on the one hand, and on the other hand, the carbon dioxide produced by the decomposition will form an inert atmosphere layer, reducing the local oxygen concentration on the powder surface to below the combustion threshold, thereby preventing the hydrogen-absorbing powder from spontaneously combusting in the air; and the NH4H2PO4 in the product will generate phosphoric acid, pyrophosphoric acid, metaphosphoric acid and ammonia after endothermic decomposition. On the one hand, pyrophosphoric acid and metaphosphoric acid will adhere to the powder surface to hinder heat transfer, and on the other hand, the ammonia produced by the decomposition will hinder the combustion of the powder, thereby effectively reducing the spontaneous combustion tendency of the powder in the air.

[0020] 5. The preparation method of the high-performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 of the present invention is simple, and the activation performance is excellent. It can absorb hydrogen after the first activation at room temperature and 6.5 MPa, and the hydrogen absorption rate is fast. At the same time, the hydrogen absorption and desorption platform pressure at room temperature is suitable, the hydrogen absorption platform pressure does not exceed 2.4 MPa, and the hydrogen desorption platform pressure is above 0.4 MPa. The hydrogen storage capacity is above 1.93 wt.%, which reaches the theoretical hydrogen storage capacity of Ti-Mn-based hydrogen storage alloy; in addition, the high-performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 does not spontaneously combust when exposed to air for 72 hours after the hydrogen absorption and desorption is completed, and has high safety. It is expected to provide efficient, practical, low-cost and safe hydrogen storage alloy raw materials for the large-scale storage and utilization of hydrogen energy in the future.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a room temperature activation curve of the high performance AB2 type hydrogen storage alloy modified with NH4H2PO4-CaCO3 prepared in Example 3 of the present invention.

[0023] Figure 2 This is a room temperature PCT curve of the high performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 prepared in Example 3 of the present invention.

[0024] Figure 3 This is a room temperature hydrogen absorption kinetics curve of the high performance AB2 type hydrogen storage alloy modified with NH4H2PO4-CaCO3 prepared in Example 3 of the present invention.

[0025] Figure 4 This is a morphology and microstructure diagram of the high-performance AB2 type hydrogen storage alloy powder modified with NH4H2PO4-CaCO3 prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0026] Example 1 The chemical formula of the high performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 in this embodiment is: Ti 0.7 Zr 0.23 Y 0.07 Mn 1.1 Cr 0.7 Fe 0.2 , and the mass ratio of AB2 type hydrogen storage alloy to NH4H2PO4 and CaCO3 is 98:1:1.

[0027] The preparation method of the high-performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 in this embodiment includes the following steps: Step 1: The chemical formula of the AB2 type hydrogen storage alloy in the high performance AB2 type hydrogen storage alloy modified by the target product NH4H2PO4-CaCO3 is Ti 0.7 Zr 0.23 Y 0.07 Mn 1.1 Cr 0.7 Fe 0.2 , selecting and weighing 9.93 g of Ti, 6.22 g of Zr, 18.81 g of Mn, 10.79 g of Cr, 1.85 g of Y, and 3.31 g of Fe metal elements, wherein the mass purity of the Ti, Zr, Mn, Cr, Y, and Fe metal elements is greater than 99.9%, and when weighing the Mn metal element, an additional 5 wt.% of Mn burnout amount is added to compensate for the burnout of the Mn metal element during smelting, and then ultrasonically cleaning and drying with a hair dryer, the cleaning agent is anhydrous ethanol, to obtain a raw material; Step 2: Mix the raw materials obtained in step 1 evenly and put them into the crucible of vacuum arc melting furnace, and evacuate the vacuum arc melting furnace to make the pressure reach 2×10 -3 Pa, fill with protective gas and wash the furnace repeatedly for 3 times, carry out vacuum arc melting under protective atmosphere of argon, the melting current is 300A~400A, turn the sample over 3 times and melt 4 times in total, and take out Ti 0.7 Zr 0.23 Y 0.07 Mn 1.1 Cr 0.7 Fe 0.2 alloy ingots; Step 3: Ti obtained in step 2 0.7 Zr 0.23 Y 0.07 Mn 1.1 Cr 0.7 Fe 0.2 The alloy ingot was cleaned with sandpaper to remove the surface oxide scale, and then washed and dried with anhydrous ethanol. Then, it was placed in a stainless steel container and transferred as a whole to a vacuum glove box. The alloy ingot was broken by beating with a stainless steel rod. Then, the broken powder was poured into a shallow agate grinding mortar for manual grinding and sieved in sequence. The powder with a particle size of 38μm~75μm was sieved to obtain Ti 0.7 Zr 0.23 Y 0.07 Mn 1.1 Cr 0.7 Fe 0.2 alloy powder; Step 4: Ti obtained in step 3 0.7 Zr 0.23 Y 0.07 Mn 1.1 Cr 0.7 Fe 0.2The alloy powder, NH4H2PO4 and CaCO3 powders were placed in a vacuum drying oven for drying. The purity of the NH4H2PO4 and CaCO3 powders was greater than 99.9%, and the sizes were all nanometers. The drying temperature was 80℃ and the time was 3h. Then 1.47g of dry Ti 0.7 Zr 0.23 Y 0.07 Mn 1.1 Cr 0.7 Fe 0.2 The alloy powder, 0.015 g of dry NH4H2PO4 powder and 0.015 g of dry CaCO3 powder were placed in a ball mill and mixed by a planetary ball mill under an argon protective atmosphere. The ball-to-material ratio of the ball milling was 5:1, the rotation speed was 250 rpm, and the mixing time was 0.5 h to obtain NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy powder.

[0028] The high performance AB2 type hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 obtained in step 4 of this embodiment was placed in the reactor of PCT equipment and vacuumed to 1×10 -4 MPa, the vacuum pump was turned off, and high-purity hydrogen was introduced until the pressure reached 6.5 MPa. Then, a room temperature hydrogen absorption / desorption cycle test was carried out for three cycles. After the cycle was completed, PCT test and hydrogen absorption kinetic test were carried out at room temperature and 6.5 MPa. The results showed that the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 could absorb hydrogen after the first activation at room temperature and 6.5 MPa without an incubation period. The PCT results showed that the room temperature hydrogen absorption platform pressure of the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 was 1.25 MPa, and the hydrogen desorption platform pressure was 0.78 MPa. The kinetic results showed that the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 had a fast hydrogen absorption rate and a hydrogen storage capacity of 1.97 wt.%. At the same time, the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 did not spontaneously combust after being exposed to air for 72 hours after hydrogen absorption and desorption.

[0029] Example 2 The chemical formula of the high performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 in this embodiment is: Ti 0.75 Zr 0.2 Y 0.05 Mn 1.15 Cr 0.65 Fe 0.2 , and the mass ratio of AB2 type hydrogen storage alloy to NH4H2PO4 and CaCO3 is 98:1:1.

[0030] The preparation method of the high-performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 in this embodiment includes the following steps: Step 1: The chemical formula of the AB2 type hydrogen storage alloy in the high performance AB2 type hydrogen storage alloy modified by the target product NH4H2PO4-CaCO3 is Ti 0.75 Zr 0.2 Y 0.05 Mn 1.15 Cr 0.65 Fe 0.2 , selecting and weighing 0.77 g of Ti, 5.47 g of Zr, 18.89 g of Mn, 10.14 g of Cr, 1.34 g of Y, and 3.35 g of Fe metal elements, wherein the mass purity of the Ti, Zr, Mn, Cr, Y, and Fe metal elements is greater than 99.9%, and when weighing the Mn metal element, an additional 5 wt.% of Mn burnout is added to compensate for the burnout of the Mn metal element during smelting, and then ultrasonically cleaning and drying with a hair dryer, the cleaning agent is anhydrous ethanol, to obtain a raw material; Step 2: Mix the raw materials obtained in step 1 evenly and put them into the crucible of vacuum arc melting furnace, and evacuate the vacuum arc melting furnace to make the pressure reach 2×10 -3 Pa, fill with protective gas and wash the furnace repeatedly for 3 times, carry out vacuum arc melting under protective atmosphere of argon, the melting current is 300A~400A, turn the sample over 3 times and melt 4 times in total, and take out Ti 0.75 Zr 0.2 Y 0.05 Mn 1.15 Cr 0.65 Fe 0.2 alloy ingots; Step 3: Ti obtained in step 2 0.7 Zr 0.23 Y 0.07 Mn 1.1 Cr 0.7 Fe 0.2 The alloy ingot was cleaned with sandpaper to remove the surface oxide scale, and then washed and dried with anhydrous ethanol. Then, it was placed in a stainless steel container and transferred as a whole to a vacuum glove box. The alloy ingot was broken by beating with a stainless steel rod. Then, the broken powder was poured into a shallow agate grinding mortar for manual grinding and sieved in sequence. The powder with a particle size of 38μm~75μm was sieved to obtain Ti 0.75 Zr 0.2 Y 0.05 Mn 1.15 Cr 0.65 Fe 0.2 alloy powder; Step 4: Ti obtained in step 3 0.75 Zr 0.2 Y0.05 Mn 1.15 Cr 0.65 Fe 0.2 The alloy powder, NH4H2PO4 and CaCO3 powders were placed in a vacuum drying oven for drying. The purity of the NH4H2PO4 and CaCO3 powders was greater than 99.9%, and the sizes were all nanometers. The drying temperature was 80℃ and the time was 3h. Then 1.47g of dry Ti 0.75 Zr 0.2 Y 0.05 Mn 1.15 Cr 0.65 Fe 0.2 The alloy powder, 0.015 g of dry NH4H2PO4 powder and 0.015 g of dry CaCO3 powder were placed in a ball mill and mixed by a planetary ball mill under an argon protective atmosphere. The ball-to-material ratio of the ball milling was 5:1, the rotation speed was 250 rpm, and the mixing time was 0.5 h to obtain NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy powder.

[0031] The high performance AB2 type hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 obtained in step 4 of this embodiment was placed in the reactor of PCT equipment and vacuumed to 1×10 -4 MPa, the vacuum pump was turned off, and high-purity hydrogen was introduced until the pressure reached 6.5 MPa. Then, a room temperature hydrogen absorption / desorption cycle test was carried out for three cycles. After the cycle was completed, PCT test and hydrogen absorption kinetic test were carried out at room temperature and 6.5 MPa. The results showed that the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 could absorb hydrogen after the first activation at room temperature and 6.5 MPa without an incubation period. The PCT results showed that the room temperature hydrogen absorption platform pressure of the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 was 1.17 MPa, and the hydrogen desorption platform pressure was 0.74 MPa. The kinetic results showed that the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 had a fast hydrogen absorption rate and a hydrogen storage capacity of 2.01 wt.%. At the same time, the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 did not spontaneously combust after being exposed to air for 72 hours after hydrogen absorption and desorption.

[0032] Example 3 The chemical formula of the high performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 in this embodiment is: Ti 0.8 Zr 0.17 Y 0.03 Mn 1.25 Cr 0.55 Fe 0.2, and the mass ratio of AB2 type hydrogen storage alloy to NH4H2PO4 and CaCO3 is 98:1:1.

[0033] The preparation method of the high-performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 in this embodiment includes the following steps: Step 1: The chemical formula of the AB2 type hydrogen storage alloy in the high performance AB2 type hydrogen storage alloy modified by the target product NH4H2PO4-CaCO3 is Ti 0.8 Zr 0.17 Y 0.03 Mn 1.25 Cr 0.55 Fe 0.2 , selecting and weighing 11.62 g of Ti, 4.7 g of Zr, 21.86 g of Mn, 8.67 g of Cr, 0.81 g of Y, and 3.39 g of Fe metal elements, wherein the mass purity of the Ti, Zr, Mn, Cr, Y, and Fe metal elements is greater than 99.9%, and when weighing the Mn metal element, an additional 5 wt.% of Mn burnout amount is added to compensate for the burnout of the Mn metal element during smelting, and then ultrasonically cleaning and drying with a hair dryer, the cleaning agent is anhydrous ethanol, to obtain a raw material; Step 2: Mix the raw materials obtained in step 1 evenly and put them into the crucible of vacuum arc melting furnace, and evacuate the vacuum arc melting furnace to make the pressure reach 2×10 -3 Pa, fill with protective gas and wash the furnace repeatedly for 3 times, carry out vacuum arc melting under protective atmosphere of argon, the melting current is 300A~400A, turn the sample over 3 times and melt 4 times in total, and take out Ti 0.8 Zr 0.17 Y 0.03 Mn 1.25 Cr 0.55 Fe 0.2 alloy ingots; Step 3: Ti obtained in step 2 0.8 Zr 0.17 Y 0.03 Mn 1.25 Cr 0.55 Fe 0.2 The alloy ingot was cleaned with sandpaper to remove the surface oxide scale, and then washed and dried with anhydrous ethanol. Then, it was placed in a stainless steel container and transferred as a whole to a vacuum glove box. The alloy ingot was broken by beating with a stainless steel rod. Then, the broken powder was poured into a shallow agate grinding mortar for manual grinding and sieved in sequence. The powder with a particle size of 38μm~75μm was sieved to obtain Ti 0.8 Zr 0.17 Y 0.03 Mn 1.25 Cr 0.55 Fe 0.2 alloy powder; Step 4: Ti obtained in step 3 0.8 Zr 0.17 Y 0.03 Mn 1.25 Cr 0.55 Fe 0.2 The alloy powder, NH4H2PO4 and CaCO3 powders were placed in a vacuum drying oven for drying. The purity of the NH4H2PO4 and CaCO3 powders was greater than 99.9%, and the sizes were all nanometers. The drying temperature was 80℃ and the time was 3h. Then 1.47g of dry Ti 0.8 Zr 0.17 Y 0.03 Mn 1.25 Cr 0.55 Fe 0.2 The alloy powder, 0.015 g of dry NH4H2PO4 powder and 0.015 g of dry CaCO3 powder were placed in a ball mill and mixed by a planetary ball mill under an argon protective atmosphere. The ball-to-material ratio of the ball milling was 5:1, the rotation speed was 250 rpm, and the mixing time was 0.5 h to obtain NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy powder.

[0034] The high performance AB2 type hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 obtained in step 4 of this embodiment was placed in the reactor of PCT equipment and vacuumed to 1×10 -4 MPa, the vacuum pump was turned off and high-purity hydrogen was introduced until the pressure reached 6.5 MPa. Then, a room temperature hydrogen absorption / desorption cycle test was carried out for three times. After the cycle was completed, PCT test and hydrogen absorption kinetic test were carried out at room temperature and 6.5 MPa. The results showed that the high-performance AB2 type hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 could absorb hydrogen after the first activation at room temperature and 6.5 MPa without incubation period. Figure 1 As shown; PCT results show that the alloy has a room temperature hydrogen absorption platform pressure of 0.87MPa and a hydrogen release platform pressure of 0.57MPa. Kinetic results show that the high performance AB2 type hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 has a fast hydrogen absorption rate and a hydrogen storage capacity of 2.00wt.%, as shown Figure 2 and Figure 3 As shown; at the same time, the high-performance AB2 type hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 did not spontaneously combust after being exposed to air for 72 hours after the hydrogen absorption and desorption was completed.

[0035] Figure 4 The morphology and microstructure of the high performance AB2 type hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 prepared in this embodiment are shown in Figure 2. Figure 4It can be seen that the AB2 type hydrogen storage alloy powder has an irregular morphology and the particle size is concentrated between 38µm and 75µm, while the nano NH4H2PO4 and CaCO3 powders are mainly attached to the surface of the AB2 type hydrogen storage alloy powder.

[0036] Example 4 The chemical formula of the high performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 in this embodiment is: Ti 0.85 Zr 0.14 Y 0.01 Mn 1.13 Cr 0.67 Fe 0.2 , and the mass ratio of AB2 type hydrogen storage alloy to NH4H2PO4 and CaCO3 is 98:1:1.

[0037] The preparation method of the high-performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 in this embodiment includes the following steps: Step 1: The chemical formula of the AB2 type hydrogen storage alloy in the high performance AB2 type hydrogen storage alloy modified by the target product NH4H2PO4-CaCO3 is Ti 0.85 Zr 0.14 Y 0.01 Mn 1.13 Cr 0.67 Fe 0.2 , selecting and weighing 12.53 g of Ti, 3.93 g of Zr, 20.07 g of Mn, 10.73 g of Cr, 0.28 g of Y, and 3.44 g of Fe metal elements, wherein the mass purity of the Ti, Zr, Mn, Cr, Y, and Fe metal elements is greater than 99.9%, and when weighing the Mn metal element, an additional 5 wt.% of Mn burnout amount is added to compensate for the burnout of the Mn metal element during smelting, and then ultrasonically cleaning and drying with a hair dryer, the cleaning agent is anhydrous ethanol, to obtain a raw material; Step 2: Mix the raw materials obtained in step 1 evenly and put them into the crucible of vacuum arc melting furnace, and evacuate the vacuum arc melting furnace to make the pressure reach 2×10 -3 Pa, fill with protective gas and wash the furnace repeatedly for 3 times, carry out vacuum arc melting under protective atmosphere of argon, the melting current is 300A~400A, turn the sample over 3 times and melt 4 times in total, and take out Ti 0.85 Zr 0.14 Y 0.01 Mn 1.13 Cr 0.67 Fe 0.2 alloy ingots; Step 3: Ti obtained in step 2 0.85 Zr 0.14 Y 0.01 Mn1.13 Cr 0.67 Fe 0.2 The alloy ingot was cleaned with sandpaper to remove the surface oxide scale, and then washed and dried with anhydrous ethanol. Then, it was placed in a stainless steel container and transferred as a whole to a vacuum glove box. The alloy ingot was broken by beating with a stainless steel rod. Then, the broken powder was poured into a shallow agate grinding mortar for manual grinding and sieved in sequence. The powder with a particle size of 38μm~75μm was sieved to obtain Ti 0.85 Zr 0.14 Y 0.01 Mn 1.13 Cr 0.67 Fe 0.2 alloy powder; Step 4: Ti obtained in step 3 0.85 Zr 0.14 Y 0.01 Mn 1.13 Cr 0.67 Fe 0.2 The alloy powder, NH4H2PO4 and CaCO3 powders were placed in a vacuum drying oven for drying. The purity of the NH4H2PO4 and CaCO3 powders was greater than 99.9%, and the sizes were all nanometers. The drying temperature was 80℃ and the time was 3h. Then 1.47g of dry Ti 0.85 Zr 0.14 Y 0.01 Mn 1.13 Cr 0.67 Fe 0.2 The alloy powder, 0.015 g of dry NH4H2PO4 powder and 0.015 g of dry CaCO3 powder were placed in a ball mill and mixed by a planetary ball mill under an argon protective atmosphere. The ball-to-material ratio of the ball milling was 5:1, the rotation speed was 250 rpm, and the mixing time was 0.5 h to obtain NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy powder.

[0038] The high performance AB2 type hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 obtained in step 4 of this embodiment was placed in the reactor of PCT equipment and vacuumed to 1×10 -4MPa, the vacuum pump was turned off, and high-purity hydrogen was introduced until the pressure reached 6.5 MPa. Then, a room temperature hydrogen absorption / desorption cycle test was carried out for three cycles. After the cycle was completed, PCT test and hydrogen absorption kinetic test were carried out at room temperature and 6.5 MPa. The results showed that the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 could absorb hydrogen after the first activation at room temperature and 6.5 MPa without an incubation period. The PCT results showed that the room temperature hydrogen absorption platform pressure of the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 was 0.87 MPa, and the hydrogen desorption platform pressure was 0.42 MPa. The kinetic results showed that the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 had a fast hydrogen absorption rate and a hydrogen storage capacity of 1.96 wt.%. At the same time, the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 did not spontaneously combust after being exposed to air for 72 hours after hydrogen absorption and desorption.

[0039] Example 5 The chemical formula of the high performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 in this embodiment is: Ti 0.9 Zr 0.1 Mn 1.2 Cr 0.6 Fe 0.2 , and the mass ratio of AB2 type hydrogen storage alloy to NH4H2PO4 and CaCO3 is 98:1:1.

[0040] The preparation method of the high-performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 in this embodiment includes the following steps: Step 1: The chemical formula of the AB2 type hydrogen storage alloy in the high performance AB2 type hydrogen storage alloy modified by the target product NH4H2PO4-CaCO3 is Ti 0.9 Zr 0.1 Mn 1.2 Cr 0.6 Fe 0.2 , selecting and weighing 12.61 g of Ti, 2.67 g of Zr, 20.25 g of Mn, 12.17 g of Cr, and 3.27 g of Fe metal elements, wherein the mass purity of the Ti, Zr, Mn, Cr, Y, and Fe metal elements is greater than 99.9%, and when weighing the Mn metal element, an additional 5 wt.% of Mn burnout is added to compensate for the burnout of the Mn metal element during smelting, and then ultrasonically cleaning and drying with a hair dryer, using anhydrous ethanol as the cleaning agent, to obtain a raw material; Step 2: Mix the raw materials obtained in step 1 evenly and put them into the crucible of vacuum arc melting furnace, and evacuate the vacuum arc melting furnace to make the pressure reach 2×10 -3Pa, fill with protective gas and wash the furnace repeatedly for 3 times, carry out vacuum arc melting under protective atmosphere of argon, the melting current is 300A~400A, turn the sample over 3 times and melt 4 times in total, and take out Ti 0.9 Zr 0.1 Mn 1.2 Cr 0.6 Fe 0.2 alloy ingots; Step 3: Ti obtained in step 2 0.9 Zr 0.1 Mn 1.2 Cr 0.6 Fe 0.2 The alloy ingot was cleaned with sandpaper to remove the surface oxide scale, and then washed and dried with anhydrous ethanol. Then, it was placed in a stainless steel container and transferred as a whole to a vacuum glove box. The alloy ingot was broken by beating with a stainless steel rod. Then, the broken powder was poured into a shallow agate grinding mortar for manual grinding and sieved in sequence. The powder with a particle size of 38μm~75μm was sieved to obtain Ti 0.9 Zr 0.1 Mn 1.2 Cr 0.6 Fe 0.2 alloy powder; Step 4: Ti obtained in step 3 0.9 Zr 0.1 Mn 1.2 Cr 0.6 Fe 0.2 The alloy powder, NH4H2PO4 and CaCO3 powders were placed in a vacuum drying oven for drying. The purity of the NH4H2PO4 and CaCO3 powders was greater than 99.9%, and the sizes were all nanometers. The drying temperature was 80℃ and the time was 3h. Then 1.47g of dry Ti 0.9 Zr 0.1 Mn 1.2 Cr 0.6 Fe 0.2 The alloy powder, 0.015 g of dry NH4H2PO4 powder and 0.015 g of dry CaCO3 powder were placed in a ball mill and mixed by a planetary ball mill under an argon protective atmosphere. The ball-to-material ratio of the ball milling was 5:1, the rotation speed was 250 rpm, and the mixing time was 0.5 h to obtain NH4H2PO4-CaCO3 modified high-performance AB2 type hydrogen storage alloy powder.

[0041] The high performance AB2 type hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 obtained in step 4 of this embodiment was placed in the reactor of PCT equipment and vacuumed to 1×10 -4MPa, the vacuum pump was turned off, and high-purity hydrogen was introduced until the pressure reached 6.5MPa. Then, a room temperature hydrogen absorption / desorption cycle test was carried out for three cycles. After the cycle was completed, PCT test and hydrogen absorption kinetic test were carried out at room temperature and 6.5MPa. The results showed that the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 could absorb hydrogen after the first activation at room temperature and 6.5MPa without an incubation period. The PCT results showed that the room temperature hydrogen absorption platform pressure of the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 was 2.39MPa, and the hydrogen desorption platform pressure was 0.57MPa. The kinetic results showed that the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 had a fast hydrogen absorption rate and a hydrogen storage capacity of 1.93wt.%. At the same time, the high-performance AB2 hydrogen storage alloy powder modified by NH4H2PO4-CaCO3 did not spontaneously combust after being exposed to air for 72 hours after hydrogen absorption and desorption.

[0042] In summary, the high-performance AB2-type hydrogen storage alloy modified with NH4H2PO4-CaCO3 prepared in this embodiment can absorb hydrogen after the first activation at room temperature, and has excellent activation performance; the hydrogen absorption and desorption platform pressure at room temperature is suitable, the hydrogen absorption platform pressure does not exceed 2.4 MPa, and the hydrogen desorption platform pressure is above 0.4 MPa; the hydrogen absorption rate is fast, and the hydrogen storage capacity is above 1.93 wt.%, reaching the theoretical hydrogen storage capacity of Ti-Mn-based hydrogen storage alloy; after the hydrogen absorption and desorption is completed, the modified hydrogen storage alloy powder does not spontaneously combust after being exposed to air for 72 h, and is expected to provide an efficient, practical, low-cost, and safe hydrogen storage alloy raw material for the large-scale storage and utilization of hydrogen energy in the future.

[0043] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A high-performance AB2 type hydrogen storage alloy modified with NH4H2PO4-CaCO3, characterized in that: The chemical formula of the AB2 type hydrogen storage alloy is: Ti a Zr 1-a-b Y b Mn x Cr 1.8-x Fe 0.2 , 0.70≤a≤0.90, 0≤b≤0.07, 1.10≤x≤1.25, a, b and x are all atomic ratios, and the mass ratio of AB2 type hydrogen storage alloy to NH4H2PO4 and CaCO3 is 98:1:

1.

2. The high-performance AB2 type hydrogen storage alloy modified by NH4H2PO4-CaCO3 according to claim 1, characterized in that: The modified high-performance AB2-type hydrogen storage alloy can absorb hydrogen upon first activation at room temperature, has a hydrogen absorption platform pressure not exceeding 2.4 MPa, a hydrogen desorption platform pressure of above 0.4 MPa, a hydrogen storage capacity of above 1.93 wt.%, and does not spontaneously combust after being exposed to air for 72 hours after hydrogen absorption and desorption.

3. A method for preparing a high-performance AB2 type hydrogen storage alloy modified with NH4H2PO4-CaCO3 as claimed in claim 1 or 2, characterized in that: The method comprises the following steps: Step 1: According to the chemical formula composition of the AB2-type hydrogen storage alloy in the target product NH4H2PO4-CaCO3-modified high-performance AB2-type hydrogen storage alloy, Ti, Zr, Mn, Cr, Y and Fe metal elements are selected, weighed and cleaned to obtain raw materials; Step 2: vacuum arc melting the raw materials obtained in step 1 to obtain an AB2 type hydrogen storage alloy ingot; Step 3: After removing the oxide scale from the AB2 hydrogen storage alloy ingot obtained in step 2, the ingot is mechanically crushed and manually ground to obtain AB2 hydrogen storage alloy powder; Step 4: Dry and ball-mill the AB2 type hydrogen storage alloy powder obtained in step 3 with NH4H2PO4 and CaCO3 powder to obtain a NH4H2PO4-CaCO3 modified high performance AB2 type hydrogen storage alloy.

4. The method for preparing a high-performance AB2 type hydrogen storage alloy modified with NH4H2PO4-CaCO3 according to claim 3, characterized in that: The mass purity of the Ti, Zr, Mn, Cr, Y and Fe metal elements described in step 1 is greater than 99.9%.

5. The method for preparing a high-performance AB2 type hydrogen storage alloy modified with NH4H2PO4-CaCO3 according to claim 3, characterized in that: When weighing the Mn metal element in step 1, an additional 5 wt.% of Mn burn-off amount needs to be added.

6. The method for preparing a high-performance AB2 type hydrogen storage alloy modified with NH4H2PO4-CaCO3 according to claim 3, characterized in that: The vacuum arc melting in step 2 has a melting current of 300A to 400A and is performed four times.

7. The method for preparing a high-performance AB2 type hydrogen storage alloy modified with NH4H2PO4-CaCO3 according to claim 3, characterized in that: The particle size of the AB2 type hydrogen storage alloy powder in step 3 is 38µm~75µm.

8. The method for preparing a high-performance AB2 type hydrogen storage alloy modified with NH4H2PO4-CaCO3 according to claim 3, characterized in that: The mass purity of the NH4H2PO4 and CaCO3 powders described in step 4 is greater than 99.9%, and the size is nanometer-scale.

9. The method for preparing a high-performance AB2 type hydrogen storage alloy modified with NH4H2PO4-CaCO3 according to claim 3, characterized in that: The drying temperature in step 4 is 80° C., the drying time is 3 h, the ball-to-material ratio of the ball mill is 5:1, the rotation speed is 250 rpm, and the mixing time is 0.5 h.

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