A low-cost AB2-type titanium-manganese-based hydrogen storage alloy without zirconium and vanadium and its preparation method

Abstract

The present invention belongs to the technical field of hydrogen storage materials, and discloses a zirconium-free, vanadium-free and low-cost AB2-type titanium-manganese-based hydrogen storage alloy and a preparation method thereof, so as to solve the problem that the existing AB2-type titanium-manganese-based hydrogen storage alloy contains zirconium, vanadium or ferrovanadium alloy. The molecular general formula of the hydrogen storage alloy is TiMn 2‑a‑b Ti a M b +x wt% R, wherein 0 < a ≤ 0.35, 0 ≤ b ≤ 1, 0 < x ≤ 5, M is one or more of Cr, Fe, Ni, Cu, Al, Si, Mo, Sn, and R is one of rare earth metals Ce, La, Sm, Y. The hydrogen storage alloy of the present invention is zirconium-free, vanadium-free and low-cost; the hydrogen storage alloy is extremely easy to activate and can be activated by one hydrogen absorption and desorption at room temperature; the hydrogen storage alloy has a high capacity, good kinetic performance and small hydrogen absorption and desorption hysteresis.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen storage materials, and particularly relates to a zirconium-free, vanadium-free, low-cost AB2-type titanium-manganese-based hydrogen storage alloy and a preparation method thereof. Background Art

[0002] Hydrogen storage alloys are typical solid-state hydrogen storage materials, including AB5 rare-earth-based alloys, AB2 titanium-based alloys, AB titanium-iron-based alloys, vanadium-based BCC alloys, and La-Mg-Ni-based alloys, etc. At present, some alloys have been applied in different fields to a certain extent. The capacity of AB5-type alloys is relatively low, generally not exceeding 1.5 wt%. The activation of AB titanium-iron-based alloys is difficult and they are prone to disproportionation reactions, with a capacity of about 1.8 wt%. Although the vanadium-based BCC alloys have a relatively high capacity (the room-temperature reversible capacity exceeds 2 wt%), they have a large hysteresis, poor cycle performance, and are expensive due to the presence of metal V. The La-Mg-Ni-based alloys are difficult to prepare because the alloy contains magnesium with a low melting point. The AB2-type titanium-manganese-based alloys have a relatively high capacity (up to 2 wt%), small hysteresis, and relatively low cost compared with other types of hydrogen storage alloys, and are receiving more and more attention. However, the existing AB2 titanium-manganese-based hydrogen storage alloys usually contain zirconium or vanadium or vanadium-iron alloys. For example, the high-entropy hydrogen storage alloys developed in the published patents CN114293086A and CN114672714A, and the titanium-chromium-manganese-based hydrogen storage alloy developed in CN114000030A all contain zirconium and pure vanadium. The hydrogen storage alloys developed in CN114555843A based on TiMn or based on TiCrMn also contain zirconium or vanadium-iron. The presence of zirconium or vanadium or vanadium-iron alloys increases the raw material cost of the alloy and affects the use and promotion of the alloy. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem that the existing AB2 titanium-manganese-based hydrogen storage alloys contain zirconium or vanadium or vanadium-iron alloys, and provide a zirconium-free, vanadium-free, low-cost AB2-type titanium-manganese-based hydrogen storage alloy and a preparation method thereof.

[0004] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A zirconium-free, vanadium-free, low-cost AB2-type titanium-manganese-based hydrogen storage alloy, the molecular general formula of the hydrogen storage alloy is TiMn 2-a-b Ti a M b +x wt% R, where 0 < a ≤ 0.35, 0 ≤ b ≤ 1, 0 < x ≤ 5, M is one or more of Cr, Fe, Ni, Cu, Al, Si, Mo, Sn, and R is one of the rare-earth metals Ce, La, Sm, Y.

[0006] The present invention also discloses a preparation method of a zirconium-free, vanadium-free, low-cost AB2-type titanium-manganese-based hydrogen storage alloy, including the following steps:

[0007] Step 1: According to the elemental composition in the molecular general formula of Claim 1, commercial metals are used for batching, and an additional 5-10 wt% of Mn and 2-5 wt% of rare earth metals are added as burn-off.

[0008] Step 2: The various metals are melted to obtain as-cast alloy. A protective gas is introduced during the melting process, and the number of melting times is 2-5 times.

[0009] Step 3: The as-cast alloy is heat-treated to obtain the final alloy. The heat treatment temperature is 900-1200 °C, and the holding time is 0.5-10 hours.

[0010] Further, the protective gas in Step 2 is argon.

[0011] Further, the heat treatment in Step 3 is low-vacuum heat treatment.

[0012] The present invention has the following beneficial effects compared with the prior art:

[0013] The main phase of the alloy of the present invention is the C14 Laves phase, or contains a small amount of titanium-rich phase and rare earth-rich phase. First, since the atomic radius of titanium is much larger than that of manganese, partially replacing manganese on the B side with titanium can play a role in adjusting the plateau, but the content of titanium should not exceed 0.35, otherwise it will exceed the solubility of titanium in the Laves phase, and a large amount of titanium-rich phase will precipitate, affecting the hydrogen storage capacity of the alloy. In addition, due to the strong adsorption force of titanium for hydrogen, an appropriate titanium content can play a role in increasing the hydrogen storage capacity and improving the activation performance. Second, by further replacing Mn on the B side with metals such as Cr, Fe, Ni, Cu, Al, Si, Mo, Sn, etc., other properties of the hydrogen storage alloy can be improved, such as the hysteresis, slope and width of the hydrogen storage plateau, and the hydrogen storage plateau pressure can also be finely adjusted according to the size of the metal atomic radius. Finally, adding a small amount of rare earth metals can act as an oxygen absorber during the alloy melting process, reducing the oxidation of the alloy. And the rare earth metals dispersed in the alloy can improve the activation performance of the alloy.

[0014] The hydrogen storage alloy of the present invention contains no zirconium and no vanadium, and has a low cost.

[0015] The hydrogen storage alloy of the present invention is extremely easy to activate and can be activated by one hydrogen absorption and desorption at room temperature.

[0016] The hydrogen storage alloy of the present invention has a high capacity, good kinetic performance, and small hydrogen absorption and desorption hysteresis. Description of the Drawings

[0017] Figure 1 is Ti 0.2 , Ti 0.25 , Ti 0.30 and Ti 0.35 The first hydrogen absorption activation kinetic curves of the alloy.

[0018] Figure 2 is Ti 0.2 ,Ti 0.25 ,Ti 0.30 and Ti 0.35 hydrogen absorption kinetic curve of the alloy for the third time.

[0019] Figure 3 is Ti 0.2 ,Ti 0.25 ,Ti 0.30 and Ti 0.35 PCT curve of the alloy at 25°C.

[0020] Figure 4 is Cr 0.25 ,Fe 0.25 ,Ni 0.25 and Cu 0.25 hydrogen absorption activation kinetic curve of the alloy for the first time.

[0021] Figure 5 is Cr 0.25 ,Fe 0.25 ,Ni 0.25 and Cu 0.25 hydrogen absorption kinetic curve of the alloy for the third time.

[0022] Figure 6 is Cr 0.25 ,Fe 0.25 ,Ni 0.25 and Cu 0.25 PCT curve of the alloy at 25°C.

[0023] Figure 7 is Cr 0.25 ,Cr 0.50 and Cr 0.75 hydrogen absorption activation kinetic curve of the alloy for the first time.

[0024] Figure 8 is Cr 0.25 ,Cr 0.50 and Cr 0.75 hydrogen absorption kinetic curve of the alloy for the third time.

[0025] Figure 9 is Cr 0.25 ,Cr 0.50 and Cr 0.75 PCT curve of the alloy at 30°C.

[0026] Figure 10 is Cu0, Cu 0.05 and Cu 0.10 hydrogen absorption activation kinetic curve of the alloy for the first time.

[0027] Figure 11Cu0, Cu 0.05 and Cu 0.10 The third hydrogen absorption kinetic curve of the alloy.

[0028] Figure 12 Cu0, Cu 0.05 and Cu 0.10 PCT curve of the alloy at 30℃. DETAILED DESCRIPTION

[0029] Example 1:

[0030] According to the molecular formula of hydrogen storage alloy TiMn 2-a-b Ti a M b +x wt% R, take a = 0.2, 0.25, 0.30, 0.35, b = 0, x = 3, R is Ce, then the alloy molecular formula is TiMn 2-a Ti a +3 wt%Ce, named Ti according to the a content 0.2 (TiMn 1.8 Ti 0.2 +3 wt%Ce), Ti 0.25 (TiMn 1.75 Ti 0.25 +3 wt%Ce), Ti 0.30 (TiMn 1.7 Ti 0.3 +3 wt% Ce) and Ti 0.35 (TiMn 1.65 Ti 0.35 +3 wt% Ce).

[0031] The hydrogen storage alloys were prepared and tested as follows:

[0032] Step 1: According to the alloying element ratio, weigh Ti, Mn, and Ce metal elements respectively, and add 5 wt% of Mn and 3 wt% of Ce.

[0033] Step 2: Use WS-4 non-consumable arc melting furnace for melting. Wash the furnace body three times before melting. After each washing, vacuum the furnace to 5×10 -3 Pa, and then filled with argon protection to make the furnace pressure reach 0.12 MPa. In order to ensure the uniformity of the alloy structure during the melting process, each alloy was turned over and remelted three times to obtain the cast alloy.

[0034] Step 3: The cast alloy is heated in a molybdenum wire furnace at low vacuum (5×10 -3 Pa), heat treatment at 1100 °C and keeping temperature for 3 h.

[0035] Step 4: The heat-treated alloy is polished with a grinding wheel to remove the surface oxide layer, and then stored in an argon glove box. Part of the alloy is slightly ground into irregular small particles for hydrogen storage performance testing, and the Sieverts method is used for hydrogen storage performance testing.

[0036] Step 5: Activation conditions: Take about 1 g of the alloy and put it into the reactor of a Sieverts-type PCT test device. Vacuum it for 30 minutes at room temperature using a vacuum pump, and then absorb hydrogen for 10 minutes under a hydrogen pressure of 6 MPa. At this time, the alloy is activated. To ensure complete activation of the alloy, hydrogen absorption and desorption are carried out two more times. As Figure 1 is Ti 0.2 , Ti 0.25 , Ti 0.30 and Ti 0.35 The first hydrogen absorption activation kinetic curves of the alloys show that all alloys can be activated at room temperature with good activation performance. And due to the strong hydrogen adsorption force of Ti, as the Ti content increases, the first hydrogen absorption capacity gradually increases. The first hydrogen absorption amounts of Ti 0.2 , Ti 0.25 , Ti 0.30 and Ti 0.35 alloys are 2.01, 2.13, 2.13 and 2.24 wt% respectively. Figure 2 is the third hydrogen absorption kinetic curve of the alloy. The alloy can be basically hydrogen saturated within 2 min, indicating good kinetic performance of the alloy. However, the third hydrogen absorption capacity of the alloy is lower than the first time, indicating that there is residual hydrogen in the alloy that cannot be released at room temperature. The third hydrogen absorption amounts of Ti 0.2 , Ti 0.25 , Ti 0.30 and Ti 0.35 alloys are 1.85, 1.94, 1.89 and 1.82 wt% respectively. Under the same conditions, Ti 0.25 has the largest reversible hydrogen storage capacity, which is 1.94 wt%.

[0037] Step 6: PCT performance testing: After the activated alloy is hydrogen absorbed and desorbed two more times, PCT performance testing is carried out at 25 °C. Figure 3 is the PCT curves of Ti 0.2 , Ti 0.25 , Ti 0.30 and Ti 0.35 alloys at 25 °C. As can be seen from the figure, as the Ti content increases, the PCT plateau of the alloy gradually decreases, and the hydrogen absorption and desorption hysteresis of the alloy gradually decreases.

[0038] Example 2:

[0039] According to the molecular general formula of the hydrogen storage alloy TiMn 2-a-b Ti a M b+x wt% R, take a = 0.25, b = 0.25, x = 3, R is Ce, then the alloy formula is TiMn 1.5 Ti 0.25 M 0.25 +3 wt%Ce, M is Cr, Fe, Ni, Cu, named Cr according to the M content 0.25 (TiMn 1.5 Ti 0.25 Cr 0.25 +3 wt%Ce), Fe 0.25 (TiMn 1.5 Ti 0.25 Fe 0.25 +3 wt%Ce), Ni 0.25 (TiMn 1.5 Ti 0.25 Ni 0.25 +3 wt% Ce) and Cu 0.25 (TiMn 1.5 Ti 0.25 Cu 0.25 +3 wt% Ce).

[0040] The hydrogen storage alloys were prepared and tested as follows:

[0041] Step 1: According to the alloying element ratio, weigh Ti, Mn, Ce, Cr, Fe, Ni, and Cu metal elements respectively, and add 5 wt% of Mn and 3 wt% of Ce.

[0042] Step 2: Use WS-4 non-consumable arc melting furnace for melting. Wash the furnace body three times before melting. After each washing, vacuum the furnace to 5×10 -3 Pa, and then filled with argon protection to bring the furnace pressure to 0.12 MPa. To ensure the uniformity of the alloy structure during the melting process, each alloy was turned over and remelted three times to obtain the cast alloy.

[0043] Step 3: The cast alloy is heated in a molybdenum wire furnace at low vacuum (5×10 -3 Pa), heat treatment at 1100 ℃ and keep warm for 3h.

[0044] Step 4: After heat treatment, the surface oxide layer of the alloy was removed using a grinding wheel, and then the alloy was stored in an argon glove box. A portion was slightly ground into irregular small particles for hydrogen storage performance testing using the Sieverts method.

[0045] Step 5. Activation conditions: Take about 1 g of the alloy and place it in the reactor of a Sieverts-type PCT test device. Evacuate it with a vacuum pump at room temperature for 30 minutes, and then absorb hydrogen under a hydrogen pressure of 6 MPa for 10 minutes. At this time, the alloy is activated. To ensure complete activation of the alloy, hydrogen absorption and desorption are performed on it two more times. As Figure 4 is Cr 0.25 , Fe 0.25 , Ni 0.25 and Cu 0.25 The first hydrogen absorption activation kinetic curves of the alloys show that all alloys can be activated at room temperature with good activation performance. The Cu 0.25 alloy shows a short incubation period, indicating that partial substitution of Cu will deteriorate the activation performance to a certain extent. Cr 0.25 , Fe 0.25 , Ni 0.25 and Cu 0.25 The first hydrogen absorption amounts of the alloys are 2.17, 2.09, 2.08 and 2.03 wt% respectively. Figure 5 is the third hydrogen absorption kinetic curve of the alloy; the alloy can be basically hydrogen absorption saturated within 2 min, indicating that the alloy has good kinetic performance. However, the third hydrogen absorption capacity of the alloy is lower than the first time, indicating that there is residual hydrogen in the alloy that cannot be released at room temperature. Cr 0.25 , Fe 0.25 , Ni 0.25 and Cu 0.25 The third hydrogen absorption amounts of the alloys are 1.96, 1.91, 1.89 and 1.70 wt% respectively. Under the same conditions, Cr 0.25 has the largest reversible hydrogen storage capacity, which is 1.96 wt%.

[0046] Step 6. PCT performance test: After the activated alloy is hydrogen absorbed and desorbed two more times, the PCT performance test is carried out at 25 °C. Figure 6 is Cr 0.25 , Fe 0.25 , Ni 0.25 and Cu 0.25 The PCT curves of the alloys at 25 °C are shown in the figure. It can be seen from the figure that although partial substitution of Cu leads to a decrease in capacity, it can significantly reduce the platform slope, and partial substitution of Cr can significantly improve the hysteresis of the platform.

[0047] Example 3:

[0048] According to the molecular general formula of the hydrogen storage alloy TiMn 2-a-b Ti a M b +x wt% R, take a = 0.25, b = 0.25, 0.50, 0.75, 1.0; x = 3, R is Ce, M is Cr, then the alloy general formula is TiMn 1.75-b Ti 0.25 Crb +3wt% Ce, named Cr according to the boron content 0.25 (TiMn 1.5 Ti 0.25 Cr 0.25 +3wt% Ce), Cr 0.50 (TiMn 1.25 Ti 0.25 Cr 0.5 +3wt% Ce), Cr 0.75 (TiMn1Ti 0.25 Cr 0.75 +3wt% Ce) and Cr 1.0 (TiMn1Ti 0.25 Cr 0.75 +3wt% Ce).

[0049] The hydrogen storage alloys were prepared and tested as follows:

[0050] Step 1: According to the alloying element ratio, weigh Ti, Mn, Ce, and Cr metal elements respectively, and add 5 wt% of Mn and 3 wt% of Ce.

[0051] Step 2: Use WS-4 non-consumable arc melting furnace for melting. Wash the furnace body three times before melting. After each washing, vacuum the furnace to 5×10 -3 Pa, and then filled with argon protection to bring the furnace pressure to 0.12 MPa. To ensure the uniformity of the alloy structure during the melting process, each alloy was turned over and remelted three times to obtain the cast alloy.

[0052] Step 3: Use molybdenum wire furnace in low vacuum (5×10 -3 Pa), heat treated at 1100 °C and kept at this temperature for 3 h.

[0053] Step 4: After heat treatment, the surface oxide layer of the alloy was removed using a grinding wheel, and then the alloy was stored in an argon glove box. A portion was slightly ground into irregular small particles for hydrogen storage performance testing using the Sieverts method.

[0054] Step 5, Activation Conditions: Take about 1 gram of alloy and place it in the reactor of Sieverts type PCT test device. Use vacuum pump to evacuate for 30 minutes at room temperature, and then absorb hydrogen at 6 MPa hydrogen pressure for 10 minutes. At this time, the alloy is activated. To ensure that the alloy is fully activated, it is subjected to hydrogen absorption and desorption twice. Figure 7 Cr 0.25 , Cr 0.50 and Cr 0.75 The first hydrogen absorption activation kinetic curve of the alloy shows that all alloys can be activated at room temperature with good activation performance. 0.25 , Cr0.50 and Cr 0.75 The initial hydrogen absorption amounts of the alloys are 2.15, 2.15 and 2.11 wt% respectively. Figure 8 Figure 5 shows the kinetic curves of the third hydrogen absorption of the alloys. The alloys can be basically hydrogen-absorbed saturated within 2 min, indicating that the alloys have good kinetic properties. However, the third hydrogen absorption capacities of the alloys are all lower than the initial ones, indicating that there is residual hydrogen in the alloys that cannot be released at room temperature. Cr 0.25 , Cr 0.50 and Cr 0.75 The third hydrogen absorption amounts of the alloys are 1.94, 1.89 and 1.84 wt% respectively. Under the same conditions, Cr 0.25 has the largest reversible hydrogen storage capacity, which is 1.94 wt%.

[0055] Step 6, PCT performance test: After the activated alloys are hydrogen-absorbed and desorbed twice again, the PCT performance test is carried out at 30 °C. Figure 9 For Cr 0.25 , Cr 0.50 and Cr 0.75 The PCT curves of the alloys at 30 °C are shown. The partial substitution of Cr can significantly improve the hysteresis of the plateau, and the plateau pressure gradually increases.

[0056] Example 4:

[0057] According to the molecular general formula of the hydrogen storage alloy TiMn 2-a-b Ti a M b +x wt% R, take a = 0.25, b = 0.25 + z; x = 1, 3, 5, R is Ce, M is Cr, Cu, the Cr content is 0.25, and the Cu content is z. Then the molecular general formula of the alloy is TiMn 1.50-z Ti 0.25 Cr 0.25 Cu z +3 wt%Ce. Take z = 0, 0.05, 0.10, and name them as Cu0 (TiMn 1.50 Ti 0.25 Cr 0.25 Cu0 + 3 wt%Ce), Cu 0.05 (TiMn 1.45 Ti 0.25 Cr 0.25 Cu 0.05 +3 wt%Ce), Cu 0.05 (TiMn 1.45 Ti 0.25 Cr 0.25 Cu 0.05 +1 wt%Ce), Cu 0.05 (TiMn 1.45 Ti0.25 Cr 0.25 Cu 0.05 +5 wt% Ce) and Cu 0.10 (TiMn 1.4 Ti 0.25 Cr 0.25 Cu 0.10 +3 wt% Ce).

[0058] The hydrogen storage alloys were prepared and tested as follows:

[0059] Step 1: According to the alloying element ratio, weigh Ti, Mn, Ce, Cr, and Cu metal elements respectively, and add 5 wt% of Mn and 3 wt% of Ce.

[0060] Step 2: Use WS-4 non-consumable arc melting furnace for melting. Wash the furnace body three times before melting. After each washing, vacuum the furnace to 5×10 -3 Pa, and then filled with argon protection to bring the furnace pressure to 0.12 MPa. To ensure the uniformity of the alloy structure during the melting process, each alloy was turned over and remelted three times to obtain the cast alloy.

[0061] Step 3: The cast alloy is heated in a molybdenum wire furnace at low vacuum (5×10 -3 Pa), heat treated at 1100 °C and kept warm for 3 h.

[0062] Step 4: After heat treatment, the surface oxide layer of the alloy was removed using a grinding wheel, and then the alloy was stored in an argon glove box. A portion was slightly ground into irregular small particles for hydrogen storage performance testing using the Sieverts method.

[0063] Step 5, Activation Conditions: Take about 1 gram of alloy and place it in the reactor of Sieverts type PCT test device. Use vacuum pump to evacuate for 30 minutes at room temperature, and then absorb hydrogen at 6 MPa hydrogen pressure for 10 minutes. At this time, the alloy is activated. To ensure that the alloy is fully activated, it is subjected to hydrogen absorption and desorption twice. Figure 10 Cu0, Cu 0.05 and Cu 0.10 The first hydrogen absorption activation kinetic curve of the alloy shows that all alloys can be activated at room temperature. As the Cu content increases, the incubation period becomes normal, indicating that too much Cu is not conducive to the activation performance. Cu0, Cu 0.05 and Cu 0.10 The initial hydrogen absorption amounts of the alloys are 2.15, 2.18, and 2.17 wt%, respectively. Figure 11is the kinetic curve of the alloy's third hydrogen absorption. The alloy can basically reach hydrogen absorption saturation within 2 minutes, indicating that the alloy has good kinetic performance. However, the hydrogen absorption capacity of the alloy in the third hydrogen absorption is lower than that in the first time, indicating that there is residual hydrogen in the alloy that cannot be released at room temperature. Cu0, Cu 0.05 and Cu 0.10 The hydrogen absorption amounts of the alloy in the third hydrogen absorption are 1.94, 1.94, and 1.86 wt% respectively. Under the same conditions, Cu 0.05 has the least impact on the capacity, which is 1.94 wt%.

[0064] Step 6, PCT performance test: After the activated alloy absorbs and releases hydrogen two more times, the PCT performance test is carried out at 30 °C. Figure 12 is Cu0, Cu 0.05 and Cu 0.10 The PCT curves of the alloy at 30 °C. Partial substitution of Cu can significantly improve the slope of the plateau and has little impact on the plateau pressure.

[0065] The Cu in this embodiment 0.05 is TiMn 1.45 Ti 0.25 Cr 0.25 Cu 0.05 + 3 wt% Ce.

Claims

1. A zirconium-free, vanadium-free, low-cost AB2-type titanium-manganese hydrogen storage alloy, the molecular formula of the hydrogen storage alloy is TiMn 2-a-b Ti a M b +xwt% R, where 0<a≤0.35, 0≤b≤1, 0<x≤5, M is one or more of Cr, Fe, Ni, Cu, Al, Si, Mo, Sn, and R is one of the rare earth metals Ce, La, Sm, and Y.

2. A method for preparing the zirconium-free and vanadium-free low-cost AB2-type titanium-manganese hydrogen storage alloy according to claim 1, characterized in that: The following steps are involved: Step 1: According to the composition of the elements in the molecular formula of claim 1, commercial metals are used for batching, and 5-10 wt% of Mn and 2-5 wt% of rare earth metals are additionally added as burn-off; Step 2: Melting the metals to obtain a cast alloy, introducing a protective gas during the melting process, and melting for 2-5 times; Step 3: heat-treating the as-cast alloy to obtain the final alloy, wherein the heat treatment temperature is 900-1200° C. and the holding time is 0.5-10 hours.

3. The method for preparing the zirconium-free and vanadium-free low-cost AB2-type titanium-manganese hydrogen storage alloy according to claim 2, characterized in that: The protective gas in step 2 is argon.

4. The method for preparing the zirconium-free and vanadium-free low-cost AB2-type titanium-manganese hydrogen storage alloy according to claim 2, characterized in that: The heat treatment in step 3 is a low vacuum heat treatment.

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