Palladium-plated AB2 type hydrogen storage alloy and preparation method thereof

Abstract

The invention discloses a palladium-plated AB2 type hydrogen storage alloy and a preparation method thereof. The palladium-plated AB2 type hydrogen storage alloy comprises an AB2 type hydrogen storage alloy and a palladium layer arranged on the surface of the AB2 type hydrogen storage alloy, the chemical general formula of the AB2 type hydrogen storage alloy is TiaZrbCrcMndNbeFef, 0.5 < = a < = 0.8, 0.2 < = b < = 0.5, 0 < = c < = 1, 1 < = d < = 2, 0 < = e < = 0.1, and 0 < = f < = 0.1; and the thickness of the palladium layer is 10-30 [mu] m. The palladium layer is electroplated on the surface of the AB2 type hydrogen storage alloy, so that the activation energy of the AB2 type hydrogen storage alloy is reduced, reversible adsorption and release of hydrogen on the AB2 type hydrogen storage alloy are promoted, and the first activation time of the AB2 type hydrogen storage alloy is shortened; in addition, additional protection is provided for the surface of the hydrogen storage alloy, oxidation and impurity accumulation on the surface of the AB2 type hydrogen storage alloy are reduced, and therefore the cycle capacity retention rate of the AB2 type hydrogen storage alloy is increased.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage technology, and more specifically, to a palladium-plated AB2 type hydrogen storage alloy and its preparation method. Background Technology

[0002] Hydrogen storage alloys are efficient and safe hydrogen storage materials capable of storing large amounts of hydrogen in the form of metal hydrides, exhibiting high hydrogen storage density. These alloys demonstrate excellent selective absorption of hydrogen, efficiently absorbing it under specific conditions and releasing high-purity hydrogen when needed, thus enabling their use in hydrogen separation and purification. Because the hydrogen absorption and release processes are reversible, hydrogen storage alloys can be repeatedly recycled, exhibiting good cycle stability and durability. Furthermore, hydrogen storage alloys release heat during hydrogen absorption and absorb heat during hydrogen release, making them promising for applications in thermal management, heat storage, and energy conversion. Compared to traditional high-pressure and liquid hydrogen storage methods, hydrogen storage alloys offer higher safety because hydrogen is atomically embedded in the alloy structure, reducing the risk of leakage and explosion during storage and transportation. Therefore, with their advantages of high hydrogen storage capacity, controlled hydrogen release, cycle stability, safety, and environmental friendliness, hydrogen storage alloys show broad application prospects in hydrogen fuel cells, hydrogen storage, water electrolysis for hydrogen production, hydrogen refueling stations, and aerospace.

[0003] AB2-type hydrogen storage alloys, especially Ti-Mn-based hydrogen storage alloys, are an important class of solid-state hydrogen storage materials. They are considered one of the most promising hydrogen storage materials due to their excellent hydrogen absorption / desorption kinetics, good cycle stability, and relatively low material cost. However, in practical applications, AB2-type hydrogen storage alloys still face technical challenges such as difficult initial activation and poor stability during long-term hydrogen absorption / desorption cycles.

[0004] Therefore, developing a palladium-plated AB2 hydrogen storage alloy that can reduce the initial activation time of AB2 type hydrogen storage alloy and improve its cycle capacity retention rate has significant economic value. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a palladium-plated AB2 type hydrogen storage alloy and its preparation method.

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

[0007] In a first aspect, the present invention provides a palladium-plated AB2-type hydrogen storage alloy, the palladium-plated AB2-type hydrogen storage alloy comprising an AB2-type hydrogen storage alloy and a palladium layer disposed on the surface of the AB2-type hydrogen storage alloy; the general chemical formula of the AB2-type hydrogen storage alloy is Ti. a Zr b Cr c Mnd Nb e Fe f Wherein, 0.5≤a≤0.8, 0.2≤b≤0.5, 0≤c≤1, 1≤d≤2, 0≤e≤0.1, and 0≤f≤0.1; the thickness of the palladium layer is 10-30μm.

[0008] The present invention relates to a palladium-plated AB2-type hydrogen storage alloy. By electroplating a palladium layer on the surface of the AB2-type hydrogen storage alloy, the activation energy of the AB2-type hydrogen storage alloy is reduced, and the surface condition of the alloy is improved. This promotes the reversible adsorption and release of hydrogen on the AB2-type hydrogen storage alloy, thereby reducing the initial activation time of the AB2-type hydrogen storage alloy. Moreover, it provides additional protection for the surface of the AB2-type hydrogen storage alloy, reducing oxidation and impurity accumulation on the surface of the AB2-type hydrogen storage alloy, thereby improving the cycle capacity retention rate of the AB2-type hydrogen storage alloy.

[0009] Preferably, 'a' is a value within a range of one or any two of the following: 0.5, 0.53, 0.55, 0.58, 0.6, 0.63, 0.65, 0.68, 0.7, 0.73, 0.75, 0.78, and 0.8.

[0010] More preferably, 0.5 ≤ a ≤ 0.7.

[0011] Preferably, b is a value within a range of one or any two of the following: 0.2, 0.23, 0.25, 0.28, 0.3, 0.33, 0.35, 0.38, 0.4, 0.43, 0.45, 0.48, and 0.5.

[0012] More preferably, 0.3≤b≤0.5.

[0013] Preferably, c is a range of one or any two of the following: 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, and 1.

[0014] More preferably, 0.6≤c≤1.

[0015] Preferably, d is a range of one or any two of the following: 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, and 2.

[0016] More preferably, 1≤d≤1.4.

[0017] Preferably, e is a range of one or any two of the following: 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, and 0.1.

[0018] More preferably, 0.04≤e≤0.1.

[0019] Preferably, f is a range of one or any two of the following: 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, and 0.1.

[0020] More preferably, 0.02≤f≤0.1.

[0021] More preferably, 0.02≤f≤0.07.

[0022] Preferably, the thickness of the palladium layer is a value within the range of one or any two of the following: 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, and 30 μm.

[0023] More preferably, the thickness of the palladium layer is 10-20 μm.

[0024] Preferably, the AB2 type hydrogen storage alloy is in sheet form.

[0025] Preferably, the thickness of the AB2 type hydrogen storage alloy is 2-10 mm.

[0026] More preferably, the thickness of the AB2 type hydrogen storage alloy is one of 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm or any combination thereof.

[0027] More preferably, the thickness of the AB2 type hydrogen storage alloy is 2-8 mm, specifically 2-5 mm.

[0028] Secondly, the present invention provides a method for preparing palladium-plated AB2 type hydrogen storage alloy, comprising the following steps:

[0029] The AB2 type hydrogen storage alloy is placed in a palladium-containing electrolyte and electroplated to obtain the palladium-plated AB2 type hydrogen storage alloy.

[0030] Preferably, the palladium-containing electrolyte includes palladium salt, conductive agent, complexing agent, brightener, wetting agent, and solvent.

[0031] More preferably, the palladium salt is at least one of palladium aminosulfonate [Pd(NH2SO3)2], palladium chloride (PdCl2), palladium nitrate [Pd(NO3)2], palladium acetate [Pd(OAc)2], sodium tetrachloropalladium (Na2PdCl4), dichlorodiamminepalladium [Pd(NH3)2Cl2], tetraaminopalladium(II) sulfate ([Pd(NH3)4]SO4), and palladium sulfate (PdSO4).

[0032] In this invention, palladium aminosulfonate [Pd(NH2SO3)2] represents "palladium aminosulfonic acid complex", which can be obtained commercially or prepared using conventional methods in the art. A method for preparing palladium aminosulfonate [Pd(NH2SO3)2] is provided herein, comprising: dissolving palladium chloride in a dilute hydrochloric acid solution, then adding aminosulfonic acid to react, thereby obtaining palladium aminosulfonate [Pd(NH2SO3)2]. The concentration of the dilute hydrochloric acid solution is 0.1-0.5 mol / L, and the solvent is water; the molar ratio of palladium chloride to aminosulfonic acid is 1:(2.0-3.0). Furthermore, palladium aminosulfonate [Pd(NH2SO3)2] needs to be stored protected from light.

[0033] More preferably, the concentration of the palladium salt is 0.01-1.0 mol / L.

[0034] More preferably, the conductive agent is at least one of aminosulfonic acid (NH2SO3H), sodium sulfate (Na2SO4), sodium nitrate (NaNO3), sodium chloride (NaCl), disodium hydrogen phosphate (Na2HPO4), potassium dihydrogen phosphate (KH2PO4), sodium acetate (CH3COONa), and sodium oxalate (Na2C2O4).

[0035] More preferably, the concentration of the conductive agent is 0.1-1.0 mol / L.

[0036] More preferably, the complexing agent is ammonium chloride (NH4Cl), citric acid (C6H8O7), tartaric acid (C4H6O6), or disodium ethylenediaminetetraacetate (EDTA disodium). 10 H 14 At least one of the following: N2Na2O8, glycine (NH2CH2COOH), triethanolamine [N(CH2CH2OH)3], lactic acid [CH3CH(OH)COOH], and sodium pyrophosphate (Na4P2O7).

[0037] More preferably, the concentration of the complexing agent is 0.01-0.2 mol / L.

[0038] More preferably, the brightening agent is sodium saccharin (C7H4NNaO3S), benzenesulfonamide (C6H5SO2NH), or Tween-80 [polyoxyethylene (20) sorbitan monooleate, C 64 H 124 O 26 [Isooctanol polyoxyethylene ether, polyvinylpyrrolidone, polyvinyl alcohol, benzyl acetone (C 10 H 10 O), methylene blue (C) 16 H 18 At least one of ClN3S).

[0039] More preferably, the concentration of the brightener is 0.001-0.01 mol / L.

[0040] More preferably, the wetting agent is sodium dodecyl sulfate (SDS, C). 12 H 25 SO4Na), nonylphenol polyoxyethylene ether [OP-10, C9H] 19 C6H4(OCH2CH2) 10 OH]、Tween-20[polyoxyethylene (20) sorbitol monolaurate, C 58 H 114 O 26 ], Laureth polyoxyethylene ether-9 [AEO-9, C 12 H 25 At least one of [(OCH2CH2)9OH].

[0041] More preferably, the concentration of the wetting agent is 0.001-0.02 mol / L.

[0042] More preferably, the solvent is at least one of water, ethanol (C2H5OH), methanol (CH3OH), isopropanol (C3H7OH), ethylene glycol (HOCH2CH2OH), and propylene glycol [CH3CH(OH)CH2OH].

[0043] Preferably, the pH of the palladium-containing electrolyte is 7-9.

[0044] More preferably, the pH adjuster of the palladium-containing electrolyte is at least one selected from ammonia, boric acid (H3BO3), phosphoric acid (H3PO4), acetic acid (CH3COOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium bicarbonate (NaHCO3), triethanolamine [N(CH2CH2OH)3], and diethanolamine [HN(CH2CH2OH)2].

[0045] Preferably, the electroplating is pulse electroplating or DC electroplating.

[0046] More preferably, the peak current density (J / L) of the pulse electroplating p The value is 0.5-5.0 A / dm. 2 .

[0047] More preferably, the pulse energizing time (T) of the pulse electroplating is... on The time is 1-100ms.

[0048] More preferably, the pulse off-time (T) of the pulse electroplating off The time is 1-200ms.

[0049] More preferably, the current density of the DC electroplating is 0.1-3.0 A / dm³. 2 .

[0050] In this invention, the palladium layer structure obtained by pulse electroplating is selected, which is beneficial to further reduce the initial activation time of AB2 type hydrogen storage alloy and improve the cycle capacity retention rate of AB2 type hydrogen storage alloy.

[0051] Preferably, the electroplating time is 5-35 minutes, specifically 5-30 minutes.

[0052] Preferably, the voltage of the electroplating is 1.0-6.0V.

[0053] Preferably, the preparation method of the AB2 type hydrogen storage alloy is as follows:

[0054] The AB2 type hydrogen storage alloy is obtained by mixing metals according to the element ratio of the general chemical formula of the AB2 type hydrogen storage alloy and performing non-consumable vacuum arc melting.

[0055] More preferably, the current of the non-consumable vacuum arc melting is 40-150A.

[0056] More preferably, the number of non-consumable vacuum arc melting processes is 3-6 times, and the duration of each vacuum arc melting process is 10-100s, specifically 20-90s.

[0057] More preferably, the vacuum degree of the non-consumable vacuum arc melting is 1.0 × 10⁻⁶. -3 -1.0×10 -2 Pa.

[0058] More preferably, the non-consumable vacuum arc melting is carried out under a protective atmosphere.

[0059] More preferably, the protective atmosphere is at least one of argon, helium, nitrogen, an argon-hydrogen mixture, and a nitrogen-hydrogen mixture.

[0060] More preferably, the non-consumable vacuum arc melting uses a water-cooled copper crucible.

[0061] More preferably, after the non-consumable vacuum arc melting, the process further includes at least one of slicing and mechanical polishing.

[0062] In this invention, the purpose of slicing after the non-consumable vacuum arc melting is to cut the AB2 type hydrogen storage alloy into slices of a certain thickness.

[0063] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0064] The present invention relates to a palladium-plated AB2-type hydrogen storage alloy. By electroplating a palladium layer on the surface of the AB2-type hydrogen storage alloy, the activation energy of the AB2-type hydrogen storage alloy is reduced, and the surface condition of the alloy is improved. This promotes the reversible adsorption and release of hydrogen on the AB2-type hydrogen storage alloy, thereby reducing the initial activation time of the AB2-type hydrogen storage alloy. Moreover, it provides additional protection for the surface of the AB2-type hydrogen storage alloy, reducing oxidation and impurity accumulation on the surface of the AB2-type hydrogen storage alloy, thereby improving the cycle capacity retention rate of the AB2-type hydrogen storage alloy.

[0065] In addition, the palladium-plated AB2 type hydrogen storage alloy of the present invention also has a high hydrogen absorption capacity.

[0066] In this invention, the palladium layer structure obtained by pulse electroplating is selected, which is beneficial to further reduce the initial activation time of AB2 type hydrogen storage alloy and improve the cycle capacity retention rate of AB2 type hydrogen storage alloy. Attached Figure Description

[0067] Figure 1 The graphs show the relationship between the initial activation time and hydrogen absorption for Example 1 and Comparative Example 4.

[0068] Figure 2 The graph shows the relationship between the number of hydrogen absorption / desorption cycles and the cycle capacity retention rate for Example 1 and Comparative Example 2.

[0069] Figure 3 The PCT curves are for Examples 1 and 5. Detailed Implementation

[0070] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0071] The experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market.

[0072] In the various embodiments and comparative examples of this invention, the preparation method of palladium aminosulfonate [Pd(NH2SO3)2] includes: adding 1 mol of palladium chloride to a 0.1 mol / L dilute hydrochloric acid solution (solvent is water), heating and stirring at 50°C to dissolve, then adding 3 mol of aminosulfonic acid and reacting for 30 min; after the reaction is complete, filtering to remove insoluble matter, adding 2 wt% activated carbon for adsorption for 30 min, filtering, and freeze-drying to obtain palladium aminosulfonate [Pd(NH2SO3)2]. The obtained product palladium aminosulfonate [Pd(NH2SO3)2] should be stored in a sealed container away from light to prevent degradation.

[0073] Example 1

[0074] This embodiment provides a palladium-plated AB2-type hydrogen storage alloy, which includes an AB2-type hydrogen storage alloy and a palladium layer disposed on the surface of the AB2-type hydrogen storage alloy; the general chemical formula of the AB2-type hydrogen storage alloy is Ti. a Zr b Cr c Mn d Nb e Fe f Wherein, a = 0.7, b = 0.3, c = 0.6, d = 1.4, e = 0.04, f = 0.02; the AB2 type hydrogen storage alloy is in sheet form with a thickness of 2 mm; the palladium layer has a thickness of 20 μm;

[0075] The preparation method of the above-mentioned palladium-plated AB2 type hydrogen storage alloy includes the following steps:

[0076] S1. According to the general chemical formula Ti for AB2 type hydrogen storage alloys 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.04 Fe 0.02 The elemental proportions of the mixed metals Ti, Zr, Cr, Mn, Nb, and Fe were transferred into a water-cooled copper crucible and heated under a protective atmosphere of argon and a vacuum degree of 1.0 × 10⁻⁶. -2 Under the condition of Pa, four consecutive non-consumable vacuum arc melting processes were performed, including: a first non-consumable vacuum arc melting process at a current of 40 A for 20 s, a second non-consumable vacuum arc melting process at a current of 80 A for 80 s, a third non-consumable vacuum arc melting process at a current of 120 A for 90 s, and a fourth non-consumable vacuum arc melting process at a current of 120 A for 90 s. After the four non-consumable vacuum arc melting processes were completed, a blocky AB2 type hydrogen storage alloy (Ti) was obtained. 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb0.04 Fe 0.02 );

[0077] S2. Use a low-speed precision cutting machine to cut the block-shaped AB2 type hydrogen storage alloy (Ti). 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.04 Fe 0.02 The material was sliced ​​to obtain sheet-like AB2 type hydrogen storage alloy (Ti) with dimensions of 5mm × 5mm × 2mm (length × width × thickness). 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.04 Fe 0.02 Then, perform mechanical polishing and set aside.

[0078] S3. Add 0.01 mol of palladium salt palladium aminosulfonate [Pd(NH2SO3)2], 0.2 mol of conductive agent aminosulfonic acid (NH2SO3H), 0.05 mol of complexing agent ammonium chloride (NH4Cl), 0.002 mol of brightening agent sodium saccharin, and 0.001 mol of wetting agent sodium dodecyl sulfate (SDS) to 0.8 L of deionized water, stir to dissolve, adjust the pH to 7.5 with ammonia and boric acid, and then add deionized water to 1 L to obtain palladium-containing electrolyte for later use;

[0079] S4. 5mm × 5mm × 2mm sheet-shaped AB2 type hydrogen storage alloy (Ti 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.04 Fe 0.02 ) was placed in 1L of palladium-containing electrolyte, and the voltage was 3.5V and the peak current density (J) was 1000 rpm. p ) is 2.5A / dm 2 Pulse energizing time (T) on The pulse turn-off time is 5ms, and the pulse turn-off time is (T). off Under the condition of 20ms, pulse electroplating is performed for 20min to obtain a palladium-plated AB2 type hydrogen storage alloy with a palladium layer thickness of 20μm.

[0080] Examples 2-3 and Comparative Examples 1-2

[0081] Examples 2-3 and Comparative Examples 1-2 provide different palladium-plated AB2-type hydrogen storage alloys. The difference between them and Example 1 lies in the thickness of the palladium layer in the palladium-plated AB2-type hydrogen storage alloy. The thickness of the palladium layer in the palladium-plated AB2-type hydrogen storage alloy is controlled by adjusting the pulse electroplating time. All other aspects are the same as in Example 1, as shown in the table below:

[0082] Table 1. Palladium layer thickness of palladium-plated AB2 type hydrogen storage alloys in Examples 1-3 and Comparative Examples 1-2.

[0083]

[0084] Examples 4-5

[0085] Examples 4-5 provide different palladium-plated AB2-type hydrogen storage alloys, which differ from Example 1 in that the thickness of the AB2-type hydrogen storage alloy is different; otherwise, they are the same as Example 1, as shown in the table below:

[0086] Table 2 shows the thickness of the AB2 type hydrogen storage alloy in Examples 1 and 4-5.

[0087]

[0088]

[0089] Examples 6-14 and Comparative Examples 3-5

[0090] Examples 6-14 and Comparative Examples 3-5 provide different palladium-plated AB2-type hydrogen storage alloys. The difference between them and Example 1 is that the general chemical formula of the AB2-type hydrogen storage alloy is different, while the rest is the same as Example 1, as shown in the table below:

[0091] Table 3. General chemical formulas of AB2-type hydrogen storage alloys in Examples 1, 6-14 and Comparative Examples 3-5

[0092] <![CDATA[Chemical general formula of AB2 type hydrogen storage alloy]]> Example 1 <![CDATA[Ti 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.04 Fe 0.02 ]]> Example 6 <![CDATA[Ti 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.1 Fe 0.02 ]]> Example 7 <![CDATA[Ti 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Fe 0.02 ]]> Example 8 <![CDATA[Ti 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.04 Fe 0.1 ]]> Example 9 <![CDATA[Ti 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.04 Fe 0.07 ]]> Example 10 <![CDATA[Ti 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.04 ]]> Example 11 <![CDATA[Ti 0.7 Zr 0.3 Cr 0.6 M N 1.4 ]]> Example 12 <![CDATA[Ti 0.7 Zr 0.3 Mn2]]> Example 13 <![CDATA[Ti 0.7 Zr 0.3 Cr1Mn1]]> Example 14 <![CDATA[Ti 0.5 Zr 0.5 Cr1Mn1]]> Comparative Example 3 <![CDATA[Ti 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.2 Fe 0.02 ]]> Comparative Example 4 <![CDATA[Ti 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.04 Fe 0.2 ]]> Comparative Example 5 <![CDATA[Ti 0.3 Zr 0.7 Cr 0.6 Mn 1.4 Nb 0.04 Fe 0.02 ]]>

[0093] Examples 15-17

[0094] Examples 15-17 provide different palladium-plated AB2 type hydrogen storage alloys, which differ from Example 1 in the type of palladium salt in the palladium-containing electrolyte. All other aspects are the same as in Example 1, as shown in the table below:

[0095] Table 4. Types of palladium salts in palladium-containing electrolytes in Examples 1, 15-17

[0096]

[0097]

[0098] Example 18

[0099] This embodiment provides a palladium-plated AB2 type hydrogen storage alloy, which differs from Embodiment 1 in that it uses DC electroplating instead of pulse electroplating. All other aspects are the same as in Embodiment 1, as detailed below:

[0100] The preparation method of the palladium-plated AB2 type hydrogen storage alloy includes the following steps:

[0101] S1. Consistent with Example 1;

[0102] S2. Same as in Example 1;

[0103] S3. Same as in Example 1;

[0104] S4. 5mm × 5mm × 2mm sheet-shaped AB2 type hydrogen storage alloy (Ti 0.7 Zr 0.3 Cr 0.6 Mn 1.4 Nb 0.04 Fe 0.02 It was placed in 1L of palladium-containing electrolyte and subjected to a voltage of 3.0V and a current density of 2.5A / dm³. 2 Under these conditions, DC electroplating is performed for 25 minutes to obtain a palladium-plated AB2 type hydrogen storage alloy with a palladium layer thickness of 20 μm.

[0105] Performance testing

[0106] The following performance tests were performed on the palladium-plated AB2 type hydrogen storage alloys of each embodiment and comparative example:

[0107] (1) Measurement of initial activation time:

[0108] The palladium-plated AB2 type hydrogen storage alloy (approximately 1.5 g by mass) from each embodiment or comparative example was placed in an automated PCT testing device (MH-PCT, China GRINM Advanced Technology & Materials Co., Ltd.), and 6.0 g of hydrogen was directly charged into the system.

[0109] High-purity hydrogen gas at MPa was introduced, and timing was started simultaneously. The hydrogen absorption rate was monitored every 6 seconds. The initial activation time was defined as the time from the start of hydrogen charging until the hydrogen absorption rate reached its maximum value (Q). max The total time (s) experienced includes the gestation period and the hydrogen absorption phase.

[0110] (2) Measurement of cyclic capacity retention:

[0111] The palladium-plated AB2 hydrogen storage alloys (approximately 1.5 g by mass) from each embodiment or comparative example were placed in an automated cycle testing device (MH-PCT, China National Research Institute of Nonferrous Metals Industry Co., Ltd.). High-purity hydrogen gas (99.99% H2 + 0.01% O2 by volume) containing 100 ppm oxygen was used as the gas source. Under the conditions of hydrogen absorption temperature of 25°C, hydrogen absorption pressure of 6.0 MPa, and hydrogen release temperature of 200°C, one hydrogen absorption / release cycle was defined as 15 min of absorption time and 25 min of release time. Multiple hydrogen absorption / release cycles were repeated, and the cycle capacity retention rate (%) was calculated using the following formula:

[0112] Cyclic capacity retention (%) = (Q100 / Q1) × 100%;

[0113] Where Q100 is the maximum hydrogen absorption capacity in the 100th hydrogen absorption / desorption cycle; Q1 is the maximum hydrogen absorption capacity in the first hydrogen absorption / desorption cycle.

[0114] (3) Measurement of maximum hydrogen absorption:

[0115] The palladium-plated AB2 hydrogen storage alloys (approximately 1.5 g by mass) of each embodiment or comparative example were subjected to high-temperature degassing treatment at 200°C. They were then placed in the reaction chamber of an automated PCT testing device (MH-PCT, China Research Institute of Nonferrous Metals & Engineering Co., Ltd.). Under constant temperature conditions of 25°C, high-purity hydrogen (purity >99.999%) was introduced into the system in stages, and the hydrogen absorption capacity of the palladium-plated AB2 hydrogen storage alloys was measured under different equilibrium pressures. The maximum equilibrium pressure during the hydrogen absorption process was set to 6 MPa, and the final hydrogen absorption capacity was defined as the maximum hydrogen absorption capacity (Q). max The value is used to reflect the hydrogen storage performance of palladium-plated AB2 type hydrogen storage alloy under isothermal and isobaric conditions.

[0116] The experimental results are shown in the table below:

[0117] Table 5 Performance test results of each embodiment and comparative example

[0118]

[0119]

[0120] Figure 1 The graphs show the relationship between the initial activation time and hydrogen absorption for Example 1 and Comparative Example 4.

[0121] Figure 2 The graph shows the relationship between the number of hydrogen absorption / desorption cycles and the cycle capacity retention rate for Example 1 and Comparative Example 2.

[0122] Figure 3 The PCT curves are for Examples 1 and 5.

[0123] From Table 5 and Figure 1-3 It is understood that the palladium-plated AB2-type hydrogen storage alloy of the present invention, by electroplating a palladium layer on the surface of the AB2-type hydrogen storage alloy, not only reduces the activation energy of the AB2-type hydrogen storage alloy, but also improves the surface state of the alloy, promotes the reversible adsorption and release of hydrogen on the AB2-type hydrogen storage alloy, thereby reducing the initial activation time of the AB2-type hydrogen storage alloy; moreover, it provides additional protection for the surface of the AB2-type hydrogen storage alloy, reduces oxidation and impurity accumulation on the surface of the AB2-type hydrogen storage alloy, thereby improving the cycle capacity retention rate of the AB2-type hydrogen storage alloy.

[0124] In addition, the palladium-plated AB2 type hydrogen storage alloy of the present invention also has a high hydrogen absorption capacity.

[0125] In this invention, the palladium layer structure obtained by pulse electroplating is selected, which is beneficial to further reduce the initial activation time of the AB2 type hydrogen storage alloy and improve the cycle capacity retention rate of the AB2 type hydrogen storage alloy.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A palladium-coated AB2-type hydrogen storage alloy, characterized by, The palladium-plated AB2-type hydrogen storage alloy comprises an AB2-type hydrogen storage alloy and a palladium layer arranged on the surface of the AB2-type hydrogen storage alloy; the AB2-type hydrogen storage alloy has a general chemical formula of Ti a Zr b Cr c Mn d Nb e Fe f , wherein 0.5≤a≤0.8, 0.2≤b≤0.5, 0≤c≤1, 1≤d≤2, 0≤e≤0.1, 0≤f≤0.1; the thickness of the palladium layer is 10-30 μm.

2. The palladium-plated AB2 type hydrogen storage alloy as described in claim 1, characterized in that, The thickness of the palladium layer is 10-20 μm.

3. The palladium-plated AB2 type hydrogen storage alloy as described in claim 1, characterized in that, At least one of (1)-(6) is included: (1)0.5≤a≤0.7； (2)0.3≤b≤0.5； (3)0.6≤c≤1； (4)1≤d≤1.4； (5)0.04≤e≤0.1； (6)0.02≤f≤0.1。 4. The palladium-plated AB2 type hydrogen storage alloy as described in claim 3, characterized in that, 0.02≤f≤0.07。 5. The palladium-plated AB2 type hydrogen storage alloy as described in claim 1, characterized in that, At least one of (1)-(2) is included: (1) The AB2-type hydrogen storage alloy is in a sheet shape; (2) The thickness of the AB2-type hydrogen storage alloy is 2-10 mm.

6. The palladium-coated AB2-type hydrogen storage alloy of claim 5, wherein the alloy contains 0.01 to 0.1% of Zr. The thickness of the AB2-type hydrogen storage alloy is 2-5 mm.

7. A method for preparing the palladium-plated AB2-type hydrogen storage alloy according to any one of claims 1-6, comprising the following steps: The AB2-type hydrogen storage alloy is placed in a palladium-containing electrolyte for electroplating, thereby obtaining the palladium-plated AB2-type hydrogen storage alloy.

8. The method for preparing palladium-plated AB2-type hydrogen storage alloy as described in claim 7, characterized in that, At least one of (1)-(4) is included: (1) The palladium-containing electrolyte comprises a palladium salt, a conductive agent, a complexing agent, a brightener, a wetting agent and a solvent; (2) The electroplating is pulse electroplating or direct current electroplating; (3) The method for preparing the AB2-type hydrogen storage alloy is: The AB2-type hydrogen storage alloy is prepared by mixing metals in the proportions of elements in the chemical general formula of the AB2-type hydrogen storage alloy and then performing non-consumable vacuum arc melting; (4) The voltage for the electroplating is 1.0-6.0 V.

9. The method for preparing palladium-plated AB2 type hydrogen storage alloy as described in claim 8, characterized in that, At least one of (1)-(4) is included: (1) the peak current density of the pulse electroplating is 0.5-5.0 A / dm 2 ; (2) The pulse on time for the pulse electroplating is 1-100 ms; (3) The pulse off time for the pulse electroplating is 1-200 ms; (4) the direct current plating has a current density of 0.1 to 3.0 A / dm 2 .

10. The method for preparing the palladium-plated AB2 type hydrogen storage alloy as described in claim 8, characterized in that, The palladium salt is at least one of palladium sulfamate, palladium chloride, palladium nitrate, palladium acetate, sodium tetrachloropalladate, dichlorodiammine palladium, tetraammine palladium sulfate and palladium sulfate.

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