A hydrogen storage alloy for nickel-hydrogen battery and its preparation method and application

Abstract

The present invention relates to the technical field of hydrogen storage alloys and provides an A5B 19 La-Y-Ni type hydrogen storage alloy and its preparation method and application. 19 The chemical composition of La-Y-Ni type hydrogen storage alloy is La 5‑x Y x Ni 19‑y R y , 2.78≤x≤3.34, 0≤y≤1.5, R is one or more of Mn, Al, Co, Zr, Cr, Sc, Ti, V, Nb and Mo. The hydrogen storage alloy provided by the present invention has good electrochemical activation performance, high discharge capacity, good cycle stability and long service life, and has broad application prospects when used as a negative electrode material for nickel-hydrogen power batteries. The preparation method provided by the present invention has high product yield, relatively mild conditions, simple process, strong operability, and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen storage alloys, in particular to an A5B 19 Type La-Y-Ni series hydrogen storage alloy and its preparation method and application. Background Art

[0002] Hydrogen energy is a secondary energy source that is abundant in source, clean, low-carbon, flexible, efficient, and widely used. It can be systematically integrated, interconnected, and complementary with heterogeneous energy types such as electricity and thermal energy. It is an important part of the clean energy system and an important carrier for energy users to achieve green and low-carbon transformation. Rare earth hydrogen storage alloys have the energy conversion function of converting chemical energy into thermal energy or mechanical energy. They have been applied to the fields of solid-state storage of hydrogen, purification and isotope separation of hydrogen, heat pumps, chemical catalysis, preparation of rare earth permanent magnet materials, and nickel-metal hydride (Ni / MH) secondary batteries. At present, the negative electrode material that has been commercially used in nickel-metal hydride batteries is mainly AB5-type rare earth hydrogen storage alloys, but the discharge capacity of this hydrogen storage alloy still needs to be improved.

[0003] Chinese patent CN106854715A discloses a lanthanum-magnesium-nickel AB3 type hydrogen storage alloy containing yttrium and its preparation process. The chemical formula of the hydrogen storage alloy is La a Y b Mg c Ca d Ni9, a, b, c, d represent the atomic ratios of the elements, 0<a≤0.65, 0<b≤0.65, 0<c, 0<d, 2.5≤a+b+c+d≤3.5. The hydrogen storage alloy contains the metal element Mg, has high production costs, and has great safety hazards.

[0004] Chinese patent CN112342438A discloses an A2B7-A7B 23 Dual-phase superlattice gas storage alloy and preparation method thereof. The alloy has A2B7 and A7B 23 Dual-phase structure, in which La is obtained by induction melting and annealing heat treatment 0.61 Pr 0.15 Mg 0.24 Ni 3.27 Alloy, when A7B 23 When the phase abundance of the type phase is 15.4%, the alloy has a maximum discharge capacity of 413mAh / g; however, the patent shows that after 100 cycles, the capacity is reduced to 80% of the original capacity, and the cycle performance still needs to be improved.

[0005] Research shows that the new superlattice structure La-YNi hydrogen storage alloy electrode has the characteristics of high electrochemical discharge capacity, easy activation, low hydrogen-induced amorphization tendency, and good reversible hydrogen absorption and desorption performance. It has great research and development value as a candidate negative electrode material for future nickel-hydrogen batteries. At present, there are many reports on the research of La-YNi A2B7 type hydrogen storage alloy. Although the A2B7 type hydrogen storage alloy has a high electrochemical discharge capacity, its charge and discharge cycle stability needs to be improved.

[0006] In summary, current hydrogen storage alloys cannot take into account both discharge capacity and cycle performance. Summary of the invention

[0007] In view of this, the present invention provides an A5B 19 La-Y-Ni type hydrogen storage alloy and its preparation method and application. 19 The La-Y-Ni hydrogen storage alloy has high discharge capacity and long cycle life, and has broad application prospects in nickel-hydrogen batteries.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] A5B 19 Type La-Y-Ni series hydrogen storage alloy, the A5B 19 The chemical composition of La-Y-Ni type hydrogen storage alloy is La 5-x Y x Ni 19-y R y , where 2.78≤x≤3.34, 0≤y≤1.5, and R is one or more of Mn, Al, Co, Zr, Cr, Sc, Ti, V, Nb and Mo.

[0010] Preferably, the A5B 19 The chemical composition of La-Y-Ni type hydrogen storage alloy is: La 1.9 Y 3.1 Ni 18.5 Mn 0.5 、La2Y3Ni 18 Mn, La 1.7 Y 3.3 Ni 18.7 Al 0.3 、La2Y3Ni 19 or La 1.8 Y 3.2 Ni 18.6 Co 0.2 Cr 0.2 .

[0011] The present invention also provides the A5B described in the above scheme 19The preparation method of the La-Y-Ni series hydrogen storage alloy comprises the following steps:

[0012] According to A5B 19 The chemical composition of the La-Y-Ni series hydrogen storage alloy is obtained by vacuum melting and pouring after mixing the intermediate alloy and the metal single substance to obtain a cast alloy ingot; the intermediate alloy is Y-Ni alloy and / or La-Ni alloy; the metal single substance is one or more of the metal single substances corresponding to La, Y, Ni and R elements;

[0013] The cast alloy ingot is subjected to microwave roasting to obtain A5B 19 Type La-Y-Ni hydrogen storage alloy.

[0014] Preferably, the microwave roasting is carried out under the protection of an inert atmosphere; the microwave roasting includes a first stage, a second stage and a third stage performed in sequence; the temperature of the first stage is 550-650°C, and the insulation time is 0.5-1.5h; the temperature of the second stage is 650-750°C, and the insulation time is 0.5-1.5h; the temperature of the third stage is 800-950°C, and the insulation time is 6-24h; and the furnace is cooled after the insulation of the third stage is completed.

[0015] Preferably, the heating rate from the temperature of the first stage to the temperature of the second stage is 5-10°C / min; the heating rate from the temperature of the second stage to the temperature of the third stage is 5-10°C / min.

[0016] Preferably, the temperature is raised to the temperature of the first stage by heating to 500-550° C. in an inert atmosphere without microwaves, and then heating to the temperature of the first stage by microwave heating.

[0017] Preferably, after the microwave roasting, the obtained A5B 19 The La-Y-Ni series hydrogen storage alloy is crushed, ball-milled and sieved in sequence; the crushing and ball-milling is carried out under the protection of an inert atmosphere; and the mesh number of the sieve used for sieving is 200 meshes.

[0018] The present invention also provides the A5B described in the above scheme 19 Type La-Y-Ni series hydrogen storage alloy or A5B prepared by the preparation method described in the above scheme 19 Application of La-Y-Ni type hydrogen storage alloys in nickel-hydrogen batteries.

[0019] The present invention also provides a nickel-hydrogen electrode, wherein the active material used in the nickel-hydrogen battery is the A5B described in the above scheme. 19 Type La-Y-Ni series hydrogen storage alloy or A5B prepared by the preparation method described in the above scheme 19Type La-Y-Ni hydrogen storage alloy.

[0020] The present invention also provides a nickel-hydrogen battery, characterized in that the negative electrode of the nickel-hydrogen battery is the nickel-hydrogen electrode described in the above solution.

[0021] The present invention provides an A5B 19 Type La-Y-Ni series hydrogen storage alloy, the A5B 19 The chemical composition of La-Y-Ni type hydrogen storage alloy is La 5-x Y x Ni 19-y R y , where 2.78≤x≤3.34, 0≤y≤1.5, and R is one or more of Mn, Al, Co, Zr, Cr, Sc, Ti, V, Nb, and Mo. A5B 19 Compared with the A2B7 type structure, the [CaCu5] substructure unit stacking type should theoretically have better structure and cycle stability during charging and discharging (hydrogen absorption and release). The hydrogen storage alloy provided by the present invention has good electrochemical activation performance, high discharge capacity, good cycle stability, and long service life. It can be used as a negative electrode material for nickel-hydrogen power batteries, has broad application prospects, and is conducive to promoting the application and development of nickel-hydrogen batteries in the new energy industry.

[0022] The present invention also provides the A5B described in the above scheme 19 A method for preparing a La-Y-Ni series hydrogen storage alloy. In the traditional method, a metal single substance is used as a raw material to prepare a hydrogen storage alloy, while the present invention uses intermediate alloys such as Y-Ni and La-Ni for formulation, which can improve the yield of hydrogen storage alloy products and reduce the generation of slag; in the traditional method, a vacuum heat treatment method is used to heat treat the cast alloy ingot, while the present invention uses microwave roasting to heat treat the alloy, which reduces the heat treatment temperature and shortens the heat treatment time, which is beneficial to saving energy consumption. Furthermore, the present invention also performs crushing and ball milling treatment on the hydrogen storage alloy, which is beneficial to further improve the electrochemical properties of the alloy. In addition, the method provided by the present invention has relatively mild reaction conditions, a simple process, strong operability, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the XRD pattern of the hydrogen storage alloy obtained in Example 1;

[0024] Figure 2 is the XRD pattern of the hydrogen storage alloy obtained in Example 2;

[0025] Figure 3 The maximum hydrogen absorption test result of the hydrogen storage alloy prepared in Example 2;

[0026] Figure 4The maximum discharge capacity test result of the hydrogen storage alloy prepared in Example 2;

[0027] Figure 5 These are the cycle performance test results of the hydrogen storage alloy prepared in Example 2. DETAILED DESCRIPTION

[0028] The present invention provides an A5B 19 Type La-Y-Ni series hydrogen storage alloy, the A5B 19 The chemical composition of La-Y-Ni type hydrogen storage alloy is La 5-x Y x Ni 19-y R y , where 2.78≤x≤3.34, 0≤y≤1.5, and R is one or more of Mn, Al, Co, Zr, Cr, Sc, Ti, V, Nb and Mo.

[0029] In the present invention, the A5B 19 The La-Y-Ni hydrogen storage alloy is a single-phase A5B 19 Type hydrogen storage alloy or A5B 19 Multiphase A5B with type phase as main phase 19 Type hydrogen storage alloy.

[0030] In the present invention, the x is preferably 3≤x≤3.3, the y is preferably 0≤y≤1, more preferably 0<y≤1, and further preferably 0.3≤y≤1; the type of the R element is one or more of Mn, Al, Co, Zr, Cr, Sc, Ti, V, Nb and Mo, preferably one or two. When there are multiple R elements, the present invention has no special requirements on the ratio of the multiple elements, and the total amount can meet the above chemical composition; in a specific embodiment of the present invention, when there are two R elements, the R is preferably Co and Cr, and the molar ratio of Co to Cr is preferably 1:1.

[0031] In the present invention, the A5B 19 The chemical composition of the La-Y-Ni type hydrogen storage alloy is preferably: La 1.9 Y 3.1 Ni 18.5 Mn 0.5 、La2Y3Ni 18 Mn, La 1.7 Y 3.3 Ni 18.7 Al 0.3 、La2Y3Ni 19 or La 1.8 Y 3.2 Ni 18.6 Co 0.2 Cr 0.2In a specific embodiment of the present invention, the above-mentioned hydrogen storage alloys are preferably single-phase A5B 19 Type La 1.9 Y 3.1 Ni 18.5 Mn 0.5 Hydrogen storage alloy, multiphase A5B 19 La2Y3Ni 18 Mn hydrogen storage alloy, multiphase A5B 19 Type La 1.7 Y 3.3 Ni 18.7 Al 0.3 Hydrogen storage alloy, multiphase A5B 19 La2Y3Ni 19 Hydrogen storage alloy or multiphase A5B 19 Type La 1.8 Y 3.2 Ni 18.6 Co 0.2 Cr 0.2 Hydrogen storage alloys.

[0032] The present invention also provides the A5B described in the above scheme 19 The preparation method of the La-Y-Ni series hydrogen storage alloy comprises the following steps:

[0033] According to A5B 19 The chemical composition of the La-Y-Ni series hydrogen storage alloy is obtained by vacuum melting and pouring after mixing the intermediate alloy and the metal single substance to obtain a cast alloy ingot; the intermediate alloy is Y-Ni alloy and / or La-Ni alloy; the metal single substance is one or more of the metal single substances corresponding to La, Y, Ni and R elements;

[0034] The cast alloy ingot is subjected to microwave roasting to obtain A5B 19 Type La-Y-Ni hydrogen storage alloy.

[0035] The present invention is based on A5B 19The chemical composition of the La-Y-Ni type hydrogen storage alloy is obtained by vacuum melting and pouring after the intermediate alloy and metal single substance ingredients to obtain a cast alloy ingot. In the present invention, the intermediate alloy is Y-Ni alloy and / or La-Ni alloy; the metal single substance is one or more of the metal single substances corresponding to La, Y, Ni and R elements; the metal single substance corresponding to the R element is specifically one or more of Mn, Al, Co, Zr, Cr, Sc, Ti, V, Nb and Mo; in the present invention, the mass fraction of the Y element in the Y-Ni alloy is preferably 50-60%, and the mass fraction of the La element in the La-Ni alloy is preferably 20-30%; in a specific embodiment of the present invention, according to the chemical ratio of the hydrogen storage alloy, Y-Ni alloy and / or La-Ni alloy are preferably used for batching, and the rest is made up with metal single substances of Y, Ni or La, and then the metal single substance corresponding to the R element is added to complete the batching process; in a specific embodiment of the present invention, considering the burnout during the smelting process, the addition amount of the metal single substance corresponding to the metal La and R element is preferably 1-3wt% in excess.

[0036] In the present invention, the vacuum melting is preferably carried out in a vacuum medium frequency induction furnace, and the temperature of the vacuum melting is preferably controlled according to the type of raw materials to ensure that all raw materials can be melted. After the raw materials are completely melted, they are preferably kept warm for 5 to 10 minutes, and then the obtained alloy liquid is quickly poured, and the cast alloy ingot is obtained after cooling. In a specific embodiment of the present invention, after the raw materials are added to the vacuum medium frequency induction furnace, it is preferably first evacuated to -30MPa, and then argon is introduced to 0.05MPa, and then the temperature is increased for melting.

[0037] After obtaining the cast alloy ingot, the present invention performs microwave roasting on the cast alloy ingot to obtain A5B 19Type La-Y-Ni series hydrogen storage alloy. In the present invention, the microwave roasting is preferably carried out under the protection of an inert atmosphere, and the inert atmosphere is preferably argon; the microwave roasting preferably includes a first stage, a second stage and a third stage in sequence; the temperature of the first stage is preferably 550-650°C, more preferably 600°C, and the holding time is preferably 0.5-1.5h, more preferably 1h; the temperature of the second stage is preferably 650-750°C, more preferably 700°C, and the holding time is preferably 0.5-1.5h, more preferably 1h; the temperature of the third stage is 800-950°C, preferably 850-900°C, and the holding time is preferably 6-24h, more preferably 10-20h; after the third stage is finished, it is cooled with the furnace; the heating rate from the temperature of the first stage to the temperature of the second stage is preferably 5-10°C / min; the heating rate from the temperature of the second stage to the temperature of the third stage is preferably 5-10°C / min. In the present invention, the heating method to the temperature of the first stage is preferably: heating to 500-550° C. under inert atmosphere protection and without microwaves, and then heating to the temperature of the first stage by microwave heating.

[0038] After the microwave roasting, the present invention preferably further comprises: 19 The La-Y-Ni series hydrogen storage alloy is crushed and ball-milled and sieved; the crushing and ball-milling is carried out under the protection of an inert atmosphere, and the inert atmosphere is preferably argon; the mesh number of the sieve for sieving is preferably 200 meshes, and the material under the sieve is taken.

[0039] In the present invention, the A5B prepared by the above method 19 The La-Y-Ni hydrogen storage alloy is a single-phase A5B 19 Type alloy, or A5B 19 In a specific embodiment of the present invention, a single-phase A5B alloy is preferably obtained by fine-tuning the melting or microwave roasting operating parameters. 19 Type alloy.

[0040] The present invention also provides A5B 19 Type La-Y-Ni series hydrogen storage alloy or A5B prepared by the preparation method described in the above scheme 19 Application of La-Y-Ni series hydrogen storage alloy in nickel-hydrogen battery; In the present invention, the A5B 19 The La-Y-Ni series hydrogen storage alloy is specifically used as the negative electrode active material of nickel-hydrogen batteries.

[0041] The present invention also provides a nickel-hydrogen electrode, wherein the active material used in the nickel-hydrogen battery is the A5B described in the above scheme. 19Type La-Y-Ni series hydrogen storage alloy or A5B prepared by the preparation method described in the above scheme 19 In the present invention, the nickel-hydrogen electrode preferably comprises a nickel strip, a nickel foam welded on the nickel strip, and an electrode sheet arranged in the nickel foam, and the raw materials used to prepare the electrode sheet preferably include A5B 19 Type La-Y-Ni series hydrogen storage alloy powder and hydroxy nickel powder; the A5B 19 The mass ratio of the La-Y-Ni type hydrogen storage alloy powder to the hydroxy nickel powder is preferably 1:4.

[0042] The present invention has no special requirements for the preparation method of the nickel-hydrogen electrode, and a method well known to those skilled in the art can be used. In a specific embodiment of the present invention, the method preferably includes the following steps:

[0043] A5B 19 La-Y-Ni series hydrogen storage alloy powder and hydroxy nickel powder are mixed and then subjected to a first cold pressing process to obtain an electrode sheet;

[0044] The electrode sheet is placed in the middle of the folded nickel foam, cold-rolled and then subjected to a second cold-rolled process, and then the nickel foam coated with the electrode sheet is spot-welded to the nickel strip to obtain the nickel-hydrogen electrode.

[0045] In the present invention, the pressure of the first cold press molding is preferably 16 MPa, and the time is preferably 8 min.

[0046] The present invention also provides a nickel-hydrogen battery, wherein the negative electrode of the nickel-hydrogen battery is the nickel-hydrogen electrode described in the above scheme. In the present invention, the nickel-hydrogen battery preferably includes a positive electrode, a negative electrode, a separator and an electrolyte; the present invention has no special requirements for the positive electrode, the separator and the electrolyte, and those known to those skilled in the art can be used.

[0047] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] In the embodiments and comparative examples, the electrochemical properties of the hydrogen storage alloys were tested using the following method:

[0049] 200 mg hydrogen storage alloy powder and 800 mg hydroxy nickel powder were accurately weighed, mixed evenly, and cold pressed for 8 minutes at a pressure of 16 MPa to form an electrode sheet of Φ16 mm × 1 mm. The electrode was placed in the middle of the folded nickel foam and cold pressed, and then spot welded with the nickel strip to obtain a hydrogen storage alloy electrode. The test device is an open-type three-electrode test system, the auxiliary electrode is a [Ni(OH)2-NiOOH] electrode, the negative electrode is a hydrogen storage alloy electrode, the reference electrode is a [Hg-HgO] electrode, the electrolyte is a KOH solution with a concentration of 6 mol / L, and the test temperature is maintained at 25 ° C by a constant temperature water bath, and the discharge capacity is recorded. The hydrogen storage alloy electrode was activated, and the alloy electrode was charged at a current density of 60 mA / g (0.2C) for 6.5 h, and then stood for 30 minutes to wait for the voltage to reach a stable state, and then discharged to 1.0 V at a current density of 60 mA / g (0.2C). After standing for 30 minutes, 60 mA / g charging and discharging were continued. This cycle was repeated for 5 weeks to obtain the maximum discharge capacity. The activated alloy electrode was charged and discharged repeatedly for 150 times at a current density of 300 mA / g (1C) to obtain the cycle stability data of the electrode.

[0050] Embodiment 1:

[0051] Single phase A5B 19 Type La 1.9 Y 3.1 Ni 18.5 Mn 0.5 Preparation of hydrogen storage alloys

[0052] Metal La, Y-Ni master alloy, metal Ni and metal Mn are used as raw materials for batching. Considering the burning loss during the smelting process, metal La and metal Mn are added in excess of 3% and 1% according to the theoretical amount. Then the raw materials are placed in a vacuum induction melting furnace, evacuated to -30MPa, and then argon gas is introduced to 0.05MPa, and the temperature is raised until the raw materials are completely melted. After smelting for 10 minutes, casting is performed and cooling is performed to obtain a cast alloy ingot; then the cast alloy ingot is placed in a vacuum heat treatment furnace, and under argon protection conditions, the temperature is raised from room temperature (25°C) to 500°C at an initial heating rate, and then microwave heating is performed, and the temperature is heated to 600°C at a heating rate of 5°C / min and kept for 1h, and then heated to 700°C at a heating rate of 5°C / min and kept for 1h, and then heated to 900°C at a heating rate of 5°C / min and kept for 16h, and finally cooled with the furnace to obtain a hydrogen storage alloy ingot. The obtained hydrogen storage alloy ingot was crushed and ball-milled under the protection of argon atmosphere, and then passed through a 200-mesh sieve to obtain alloy powder. The alloy yield was 98.25%. Figure 1 The XRD pattern of the hydrogen storage alloy obtained in Example 1; Figure 1 The results show that the hydrogen storage alloy prepared in this example is a single-phase A5B 19 Type alloy.

[0053] The alloy powder that passed through a 200-mesh sieve was subjected to electrochemical performance testing. The test results showed that the maximum discharge capacity of the hydrogen storage alloy was 375.6 mAh / g, and the capacity retention rate after 150 charge and discharge cycles was S 150 It is 91.6%, and the maximum hydrogen absorption capacity is 1.42wt%.

[0054] Embodiment 2:

[0055] Multiphase A5B 19 La2Y3Ni 18 Preparation of Mn hydrogen storage alloy:

[0056] Metal La, Y-Ni master alloy, metal Ni and metal Mn are used as raw materials for batching. Considering the burning loss during the smelting process, metal La and metal Mn are added in excess of 2% and 2% according to the theoretical amount. The raw materials are placed in a vacuum induction melting furnace, evacuated to -30MPa, and then argon gas is introduced to 0.05MPa, and the temperature is raised until the raw materials are completely melted. After smelting for 10 minutes, the cast alloy ingot is cast and cooled to obtain a cast alloy ingot; then the cast alloy ingot is placed in a vacuum heat treatment furnace, and under argon protection conditions, the temperature is raised from room temperature (25°C) to 500°C at an initial heating rate, and then microwave heating treatment is performed, heating to 600°C at a heating rate of 5°C / min and keeping it for 1h, then heating to 700°C at a heating rate of 8°C / min and keeping it for 1h, and then heating to 950°C at a heating rate of 8°C / min and keeping it for 10h, and finally cooling with the furnace to obtain a hydrogen storage alloy ingot. The obtained hydrogen storage alloy ingot was crushed and ball-milled under the protection of argon atmosphere, and then passed through a 200-mesh sieve to obtain alloy powder. The alloy yield was 97.95%.

[0057] Figure 1 is the XRD diagram of the hydrogen storage alloy obtained in Example 2. Figure 1 It can be seen that the hydrogen storage alloy prepared in this embodiment is A5B 19 A hydrogen storage alloy mainly composed of A2B7 phase and a small amount of A2B7 phase.

[0058] The alloy powder that passed through a 200-mesh sieve was tested for electrochemical properties. The test results showed that the maximum discharge capacity of the alloy was 370.2 mAh / g, and the capacity retention rate after 150 charge and discharge cycles was S 150 It is 86.8%, and the maximum hydrogen absorption capacity is 1.36wt%. Figure 2 The maximum hydrogen absorption test result of the hydrogen storage alloy prepared in Example 2; Figure 3 The maximum discharge capacity test result of the hydrogen storage alloy prepared in Example 2; Figure 4 These are the cycle performance test results of the hydrogen storage alloy prepared in Example 2.

[0059] Embodiment 3:

[0060] Multiphase A5B 19 Type La 1.7 Y 3.3 Ni 18.7 Al 0.3 Preparation of hydrogen storage alloys:

[0061] The raw materials are La-Ni master alloy, Y-Ni master alloy, metal Ni and metal Al. Considering the burning loss during the smelting process, metal Al is added in excess of 3% according to the theoretical amount. The raw materials are placed in a vacuum induction melting furnace, evacuated to -30MPa, and then argon gas is introduced to 0.05MPa, and the temperature is raised until the raw materials are completely melted. After smelting for 10 minutes, the cast alloy ingot is cast and cooled to obtain a cast alloy ingot; then the cast alloy ingot is placed in a vacuum heat treatment furnace, and under argon protection conditions, the temperature is raised from room temperature (25°C) to 500°C at an initial heating rate, and then microwave heating treatment is performed, and the temperature is heated to 600°C at a heating rate of 5°C / min and kept for 1h, and then heated to 700°C at a heating rate of 5°C / min and kept for 1h, and then heated to 900°C at a heating rate of 5°C / min and kept for 24h, and finally cooled with the furnace to obtain a hydrogen storage alloy ingot. The obtained hydrogen storage alloy ingot was crushed and ball-milled under argon atmosphere protection, and then passed through a 200-mesh sieve to obtain alloy powder with an alloy yield of 98.03%. The obtained hydrogen storage alloy was subjected to XRD test. The results showed that the hydrogen storage alloy prepared in this embodiment was A5B 19 Type phase-based hydrogen storage alloy.

[0062] The alloy powder that passed through a 200-mesh sieve was subjected to electrochemical performance testing. The test results showed that the maximum discharge capacity of the alloy was 372.5 mAh / g, and the capacity retention rate after 150 charge and discharge cycles was S 150 It is 84.5%, and the maximum hydrogen absorption capacity is 1.32wt%.

[0063] Embodiment 4:

[0064] Multiphase A5B 19 La2Y3Ni 19 Preparation of hydrogen storage alloys:

[0065] Metal La, Y-Ni master alloy, and metal Ni are used as raw materials for batching. Considering the burning loss during the smelting process, metal La is added in excess of 2% of the theoretical amount. The raw materials are placed in a vacuum induction melting furnace, evacuated to -30MPa, and then argon is introduced to 0.05MPa, and the temperature is raised until the raw materials are completely melted. After smelting for 10 minutes, the cast alloy ingot is cast and cooled to obtain a cast alloy ingot; then the cast alloy ingot is placed in a vacuum heat treatment furnace, and under argon protection conditions, the temperature is raised from room temperature (25°C) to 500°C at an initial heating rate, and then microwave heating is performed, heated to 600°C at a heating rate of 5°C / min and kept for 1h, then heated to 700°C at a heating rate of 5°C / min and kept for 1h, and then heated to 900°C at a heating rate of 5°C / min and kept for 12h, and finally cooled with the furnace to obtain a hydrogen storage alloy ingot. The obtained hydrogen storage alloy ingot was crushed and ball-milled under argon atmosphere protection, and then passed through a 200-mesh sieve to obtain alloy powder with an alloy yield of 97.15%. The obtained hydrogen storage alloy was subjected to XRD test. The results showed that the hydrogen storage alloy prepared in this embodiment was A5B 19 Type phase-based hydrogen storage alloy.

[0066] The alloy powder that passed through a 200-mesh sieve was subjected to electrochemical performance testing. The test results showed that the maximum discharge capacity of the alloy was 365.8 mAh / g, and the capacity retention rate after 150 charge and discharge cycles was S 150 It is 78.8%, and the maximum hydrogen absorption capacity is 1.29wt%.

[0067] Embodiment 5:

[0068] Multiphase A5B 19 Type La 1.8 Y 3.2 Ni 18.6 Co 0.2 Cr 0.2 Preparation of hydrogen storage alloys:

[0069] The raw materials are La-Ni master alloy, Y-Ni master alloy, metal Ni, metal Co and metal Cr. Considering the burning loss during the smelting process, metal Co and metal Cr are added in excess of 2% of the theoretical amount. Then, the raw materials are placed in a vacuum induction melting furnace, evacuated to -30MPa, and then argon gas is introduced to 0.05MPa, and the temperature is raised until the raw materials are completely melted. After smelting for 10 minutes, the cast alloy ingot is cast and cooled to obtain a cast alloy ingot; then, the cast alloy ingot is placed in a vacuum heat treatment furnace, and under argon protection conditions, the temperature is raised from room temperature (25°C) to 500°C at an initial heating rate, and then microwave heating treatment is performed, and the temperature is heated to 600°C at a heating rate of 6°C / min and kept for 1h, and then heated to 700°C at a heating rate of 6°C / min and kept for 1h, and then heated to 900°C at a heating rate of 6°C / min and kept for 20h, and finally cooled with the furnace to obtain a hydrogen storage alloy ingot. The obtained hydrogen storage alloy ingot was crushed and ball-milled under argon atmosphere protection, and then passed through a 200-mesh sieve to obtain alloy powder with an alloy yield of 98.22%. The obtained hydrogen storage alloy was subjected to XRD test. The results showed that the hydrogen storage alloy prepared in this embodiment was A5B 19 Type phase-based hydrogen storage alloy.

[0070] The alloy powder that passed through a 200-mesh sieve was subjected to electrochemical performance testing. The test results showed that the maximum discharge capacity of the alloy was 370.5 mAh / g, and the capacity retention rate after 150 charge and discharge cycles was S 150 It is 83.6%, and the maximum hydrogen absorption capacity is 1.34wt%.

[0071] Comparative Example 1:

[0072] Multiphase A5B 19 La2Y3Ni 18 Preparation of Mn Hydrogen Storage Alloy

[0073] Metal La, metal Y, metal Ni and metal Mn are used as raw materials for batching. Considering the burning loss during the smelting process, metal La and metal Mn are added in excess of 2% and 2% according to the theoretical amount. Then put it into a vacuum induction melting furnace, evacuate to -30MPa, then introduce argon gas to 0.05MPa, heat it until the raw materials are completely melted, keep it warm for 10min, then cast it, and cool it to obtain a cast alloy ingot; then place the cast alloy ingot in a vacuum heat treatment furnace, under argon protection conditions, heat it from room temperature (25℃) to 500℃ at an initial heating rate, heat it to 600℃ at a heating rate of 5℃ / min and keep it warm for 1h, then heat it to 700℃ at a heating rate of 8℃ / min and keep it warm for 1h, then heat it to 950℃ at a heating rate of 8℃ / min and keep it warm for 10h, finally cool it with the furnace to obtain a hydrogen storage alloy ingot. The obtained hydrogen storage alloy ingot was crushed and ball-milled under the protection of argon atmosphere, and then passed through a 200-mesh sieve to obtain alloy powder. The alloy yield was 84.63%.

[0074] The alloy powder that passed through a 200-mesh sieve was tested for electrochemical properties. The test results showed that the maximum discharge capacity of the alloy was 342.2 mAh / g, and the capacity retention rate after 150 charge and discharge cycles was S 150 It is 72.5%, and the maximum hydrogen absorption capacity is 1.28wt%.

[0075] In Comparative Example 1, a single metal substance is used as a raw material to prepare a hydrogen storage alloy, and the traditional method is used for heating. The alloy is not subjected to microwave roasting. The performance indicators of the obtained hydrogen storage alloy are lower than those of Example 2 of the present invention, and the yield of the alloy is also lower.

[0076] Comparative Example 2:

[0077] Multiphase A5B 19 La2Y3Ni 18 Preparation of Mn Hydrogen Storage Alloy

[0078] Metal La, metal Y, metal Ni and metal Mn are used as raw materials for batching. Considering the burning loss during the smelting process, metal La and metal Mn are added in excess of 2% and 2% according to the theoretical amount. Then put it into a vacuum induction melting furnace, evacuate to -30MPa, then introduce argon gas to 0.05MPa, heat it until the raw materials are completely melted, keep it warm for 10min, then cast it, and cool it to obtain a cast alloy ingot; then place the cast alloy ingot in a vacuum heat treatment furnace, under argon protection conditions, heat it from room temperature (25℃) to 500℃ at an initial heating rate, then perform microwave heating treatment, heat it to 600℃ at a heating rate of 5℃ / min and keep it warm for 1h, then heat it to 700℃ at a heating rate of 8℃ / min and keep it warm for 1h, then heat it to 950℃ at a heating rate of 8℃ / min and keep it warm for 10h, and finally cool it with the furnace to obtain a hydrogen storage alloy ingot. The obtained hydrogen storage alloy ingot was crushed and ball-milled under the protection of argon atmosphere, and then passed through a 200-mesh sieve to obtain alloy powder. The alloy yield was 87.85%.

[0079] The alloy powder that passed through a 200-mesh sieve was subjected to electrochemical performance testing. The test results showed that the maximum discharge capacity of the alloy was 346.1 mAh / g, and the capacity retention rate after 150 charge and discharge cycles was S 150 It is 76.5%, and the maximum hydrogen absorption capacity is 1.31wt%.

[0080] In Comparative Example 2, a hydrogen storage alloy is prepared using a metal element as a raw material, and the heat treatment method is microwave roasting. Compared with Example 2, the various performance indicators of the hydrogen storage alloy prepared in Comparative Example 2 are lower, but compared with Comparative Example 1, the maximum discharge capacity, capacity retention rate and maximum hydrogen absorption capacity are slightly improved.

[0081] Comparative Example 3:

[0082] Multiphase A5B 19 La2Y3Ni 18 Preparation of Mn hydrogen storage alloy:

[0083] Metal La, Y-Ni master alloy, metal Ni and metal Mn are used as raw materials for batching. Considering the burning loss during the smelting process, metal La and metal Mn are added in excess of 2% and 2% according to the theoretical amount. Then put it into a vacuum induction melting furnace, evacuate to -30MPa, then introduce argon gas to 0.05MPa, heat it until the raw materials are completely melted, keep it warm for 10min, then cast it, and cool it to obtain a cast alloy ingot; then place the cast alloy ingot in a vacuum heat treatment furnace, under argon protection conditions, heat it from room temperature (25℃) to 500℃ at an initial heating rate, heat it to 600℃ at a heating rate of 5℃ / min and keep it warm for 1h, then heat it to 700℃ at a heating rate of 8℃ / min and keep it warm for 1h, then heat it to 950℃ at a heating rate of 8℃ / min and keep it warm for 10h, finally cool it with the furnace to obtain a hydrogen storage alloy ingot. The obtained hydrogen storage alloy ingot was crushed and ball-milled under the protection of argon atmosphere, and then passed through a 200-mesh sieve to obtain alloy powder. The alloy yield was 97.43%.

[0084] The alloy powder that passed through a 200-mesh sieve was subjected to electrochemical performance testing. The test results showed that the maximum discharge capacity of the alloy was 351.1 mAh / g, and the capacity retention rate after 150 charge and discharge cycles was S 150 It is 83.6%, and the maximum hydrogen absorption capacity is 1.33wt%.

[0085] In Comparative Example 3, an intermediate alloy is used for batching, and the cast alloy ingot is treated by a traditional heating method. Compared with Comparative Examples 1 to 2, the alloy yield is greatly improved, but the various indicators of the hydrogen storage alloy are still lower than those of Example 2.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A5B 19 A method for preparing a La-Y-Ni type hydrogen storage alloy, characterized in that: The following steps are involved: According to A5B 19 The chemical composition of the La-Y-Ni series hydrogen storage alloy is obtained by vacuum melting and pouring after mixing the intermediate alloy and the metal single substance to obtain a cast alloy ingot; the intermediate alloy is Y-Ni alloy and / or La-Ni alloy; the metal single substance is one or more of the metal single substances corresponding to La, Y, Ni and R elements; The cast alloy ingot is subjected to microwave roasting to obtain A5B 19 Type La-Y-Ni series hydrogen storage alloy; The A5B 19 The chemical composition of La-Y-Ni type hydrogen storage alloy is La 5-x Y x Ni 19-y R y , wherein 2.78≤x≤3.34, 0≤y≤1.5, and R is one or more of Mn, Al, Co, Zr, Cr, Sc, Ti, V, Nb and Mo; The microwave roasting is carried out under the protection of an inert atmosphere; the microwave roasting includes a first stage, a second stage and a third stage in sequence; the temperature of the first stage is 550-650°C, and the insulation time is 0.5-1.5h; the temperature of the second stage is 650-750°C, and the insulation time is 0.5-1.5h; the temperature of the third stage is 800-950°C, and the insulation time is 6-24h; after the insulation of the third stage is completed, the furnace is cooled.

2. The preparation method according to claim 1, characterized in that: The A5B 19 The chemical composition of La-Y-Ni type hydrogen storage alloy is: La 1.9 Y 3.1 Ni 18.5 Mn 0.5 、La2Y3Ni 18 Mn, La 1.7 Y 3.3 Ni 18.7 Al 0.3 、La2Y3Ni 19 or La 1.8 Y 3.2 Ni 18.6 Co 0.2 Cr 0.2 .

3. The preparation method according to claim 1, characterized in that: The heating rate from the temperature of the first stage to the temperature of the second stage is 5-10°C / min; the heating rate from the temperature of the second stage to the temperature of the third stage is 5-10°C / min.

4. The preparation method according to claim 1 or 3, characterized in that: The heating method for heating to the temperature of the first stage is: heating to 500-550° C. in the absence of microwaves under the protection of an inert atmosphere, and then heating to the temperature of the first stage by microwave heating.

5. The preparation method according to claim 1, characterized in that: After the microwave roasting, the obtained A5B 19 The La-Y-Ni series hydrogen storage alloy is crushed, ball-milled and sieved in sequence; the crushing and ball-milling is carried out under the protection of an inert atmosphere; and the mesh number of the sieve used for sieving is 200 meshes.

6. A5B prepared by the preparation method according to any one of claims 1 to 5 19 Application of La-Y-Ni type hydrogen storage alloys in nickel-hydrogen batteries.

7. A nickel-hydrogen electrode, characterized in that: The active material used in the nickel-hydrogen electrode is A5B prepared by the preparation method according to any one of claims 1 to 5. 19 Type La-Y-Ni hydrogen storage alloy.

8. A nickel-hydrogen battery, characterized in that: The negative electrode of the nickel-hydrogen battery is the nickel-hydrogen electrode according to claim 7.

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