Metal Hydrides: Fundamentals and Applications

Topic Information

Dear Colleagues,

Metal hydrides are good candidates for hydrogen storage in a large range of practical applications. A lot of research activities are currently taking place, focusing on finding new metal hydrides that will meet the needs of industry and also how the present metal hydrides could be modified to improve their present characteristics. Therefore, there is a clear need to have a better fundamental understanding of hydrogenation/dehydrogenation reaction in metal hydrides with the perspective of practical applications. The goal of this Topic is to present the latest advancements in the understanding of the formation of metal hydrides and the use of metal hydrides for practical applications. Experimental as well as theoretical (simulation, machine learning, DFT calculation) papers are welcome. Contributions on novel materials (high entropy alloys, nanocrystalline, composite, etc.), processing techniques (severe plastic deformation, ball milling, heat treatment, etc.), and on specialized characterization techniques (neutron diffraction, in operando) are welcome. Scientists from a wide range of disciplines are invited to contribute to this Topic. The potential topics include but are not limited to:

• New metal hydrides for hydrogen storage;
• High-entropy alloys; 
• Nanocrystalline metal hydrides;
• Catalysts; 
• Processing;
• Characterization;
• Electrochemical applications;
• In situ characterizations;
• Novel utilization.

Prof. Dr. Jacques Huot
Prof. Dr. Fusheng Yang
Dr. Giovanni Capurso
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Compounds compounds	2.3	3.8	2021	22.8 Days	CHF 1200
Energies energies	3.2	7.3	2008	16.2 Days	CHF 2600
Hydrogen hydrogen	3.0	5.5	2020	17.6 Days	CHF 1200
Materials materials	3.2	6.4	2008	15.2 Days	CHF 2600
Metals metals	2.5	5.3	2011	18 Days	CHF 2600

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Published Papers (8 papers)

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10 pages, 1602 KiB  

Open AccessArticle

Hydrogenation Thermodynamics of Ti₁₆V₆₀Cr_24−xFe_x Alloys (x = 0, 4, 8, 12, 16, 20, 24)

by Francia Ravalison and Jacques Huot

Hydrogen 2024, 5(1), 29-38; https://doi.org/10.3390/hydrogen5010003 - 26 Jan 2024

Cited by 1 | Viewed by 8131

Abstract

The effect of the partial substitution of Cr with Fe on the thermodynamic parameters of vanadium-rich Ti₁₆V₆₀Cr_24-xFe_x alloys (x = 0, 4, 8, 12, 16, 20, 24) was investigated. For each composition, a pressure–concentration isotherm (PCI) [...] Read more.

The effect of the partial substitution of Cr with Fe on the thermodynamic parameters of vanadium-rich Ti₁₆V₆₀Cr_24-xFe_x alloys (x = 0, 4, 8, 12, 16, 20, 24) was investigated. For each composition, a pressure–concentration isotherm (PCI) was registered at 298, 308, and 323 K. The PCI curves revealed a reduction in plateau pressure and a decrease in desorbed hydrogen capacity with an increasing amount of Fe. For all alloys, about 50% or less of the initial hydrogen capacity was desorbed for all chosen temperatures. Entropy (ΔS) and enthalpy (ΔH) values were deducted from corresponding Van’t Hoff plots of the PCI curves: the entropy values ranged from −150 to −57 J/K·mol H₂, while the enthalpy values ranged from −44 to −21 kJ/mol H₂. They both decreased with an increasing amount of Fe. Plotting ΔS as function of ΔH showed a linear variation that seems to indicate an enthalpy–entropy compensation. Moreover, a quality factor analysis demonstrated that the present relationship between entropy and enthalpy is not of a statistical origin at the 99% confidence level. Full article

(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)

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21 pages, 5791 KiB  

Open AccessArticle

Design of LPSO Phases in Mg-Y-Ni Alloys to Impact Hydrogenation Kinetics

by Kyle S. Nicholson, Vladimir Skripnyuk, Chunjie Xu, Xiang Gao, Eugen Rabkin, Peter D. Hodgson and Rimma Lapovok

Hydrogen 2023, 4(3), 658-678; https://doi.org/10.3390/hydrogen4030042 - 10 Sep 2023

Cited by 2 | Viewed by 2099

Abstract

A series of Mg-Y-Ni alloys with different volume fractions of long-period stacking-ordered (LPSO) phase were prepared, by controlling the alloy composition, heat treatment, and single-pass extrusion, to assess the influence of increasing LPSO phase volume fraction on the hydrogen absorption and desorption properties [...] Read more.

A series of Mg-Y-Ni alloys with different volume fractions of long-period stacking-ordered (LPSO) phase were prepared, by controlling the alloy composition, heat treatment, and single-pass extrusion, to assess the influence of increasing LPSO phase volume fraction on the hydrogen absorption and desorption properties of the extruded alloys. The LPSO phase volume fraction in the alloys increased with increasing solute concentration, from ~24% LPSO in Mg₉₇Y₂Ni₁ (at.%) to ~60% LPSO in Mg₉₃Y₄Ni₃ (at.%) up to ~92% LPSO in Mg₉₁Y₅Ni₄ (at.%). The most refined microstructure was obtained in the alloy with highest volume fraction of LPSO phase. After 100 s at 300 °C, the Mg₉₁Y₅Ni₄ alloy absorbed 4.6 ± 0.2 wt.% H while the Mg₉₇Y₂Ni₁ and Mg₉₃Y₄Ni₃ alloys each absorbed 3.8 ± 0.2 wt.% H. After 10,000 s at 300 °C, all three alloys had absorbed a maximum of 5.3 ± 0.2 wt.% H with no further significant difference in hydrogen absorption kinetics. The Mg₉₁Y₅Ni₄ alloy desorbed 1.8 ± 0.2 wt.% H after 100 s at 300 °C against a vacuum while the Mg₉₇Y₂Ni₁ and Mg₉₃Y₄Ni₃ alloys desorbed 0.8 ± 0.2 wt. H and 0.6 ± 0.2 wt.% H, respectively. After 10,000 s at 300 °C, the Mg₉₁Y₅Ni₄ and Mg₉₇Y₂Ni₁ alloys completely desorbed 5.2 ± 0.2 wt.% H and 5.4 ± 0.2 wt.% H, respectively, but the Mg₉₃Y₄Ni₃ alloy desorbed only 3.7 ± 0.2 wt.% H. Hydrogen absorption and desorption kinetics were fastest in the Mg₉₁Y₅Ni₄ alloy with the highest LPSO volume fraction, but no consistent trend with LPSO phase volume fraction was observed with the Mg₉₃Y₄Ni₃ alloy, which showed the slowest absorption and desorption kinetics. The hydrogen pressures corresponding to metal–hydride equilibrium did not vary with LPSO phase volume fraction or alloy composition, indicating that the (de)hydrogenation thermodynamics were not significantly changed in any of the alloys. Hydrogen absorption experiments with thin foils, made of extruded Mg₉₁Y₅Ni₄ alloy with the highest LPSO phase fraction, demonstrated that the LPSO structures decompose into Mg phase, Mg₂Ni phase, lamellar Mg/Mg-Y structures, and YH_x particles. This study shows that hydrogen kinetics can be impacted in Mg-Y-Ni alloys by controlling the LPSO phases using common metallurgical techniques. Full article

(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)

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14 pages, 4900 KiB  

Open AccessArticle

Microstructure Characteristics and Hydrogen Storage Kinetics of Mg_77+xNi_20−xLa₃ (x = 0, 5, 10, 15) Alloys

by Hongxiao Tian, Qichang Wang, Xia Li, Long Luo and Yongzhi Li

Materials 2023, 16(13), 4576; https://doi.org/10.3390/ma16134576 - 25 Jun 2023

Cited by 3 | Viewed by 1535

Abstract

Mg_77+xNi_20−xLa₃ (x = 0, 5, 10, 15) alloys were successfully prepared by the vacuum induction melting method. The structural characterizations of the alloys were performed by using X-ray diffraction and scanning electron microscope. The effects [...] Read more.

Mg_77+xNi_20−xLa₃ (x = 0, 5, 10, 15) alloys were successfully prepared by the vacuum induction melting method. The structural characterizations of the alloys were performed by using X-ray diffraction and scanning electron microscope. The effects of nickel content on the microstructure and hydrogen storage kinetic of the as-cast alloys were investigated. The results showed that the alloys are composed of a primary phase of Mg₂Ni, lamella eutectic composites of Mg + Mg₂Ni, and some amount of LaMg₁₂ and La₂Mg₁₇. Nickel addition significantly improved the hydrogen-absorption kinetic performance of the alloy. At 683 K, Mg₇₇Ni₂₀La₃ alloy and Mg₈₂Ni₁₅La₃ alloy underwent hydrogen absorption and desorption reactions for 2 h, respectively, and their hydrogen absorption and desorption capacities were 4.16 wt.% and 4.1 wt.%, and 4.92 wt.% and 4.69 wt.%, respectively. Using the Kissinger equation, it was calculated that the activation energy values of Mg₇₇Ni₂₀La₃, Mg₈₂Ni₁₅La₃, Mg₈₇Ni₁₀La₃ and Mg₉₂Ni₅La₃ alloys were in the range of 68.5~75.2 kJ/mol, much lower than 150~160 kJ/mol of MgH₂. Full article

(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)

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10 pages, 3716 KiB  

Open AccessArticle

Hydrogen Absorption Performance and O₂ Poisoning Resistance of Pd/ZrCo Composite Film

by Yiyao Qian, Ruijun Qian, Hetian Feng, Dachuan Zhu and Chaoling Wu

Materials 2023, 16(8), 3159; https://doi.org/10.3390/ma16083159 - 17 Apr 2023

Cited by 1 | Viewed by 1639

Abstract

In order to enhance the hydrogen absorption performance and poisoning resistance of ZrCo to O₂, Pd/ZrCo composite films were prepared by direct current magnetron sputtering. The results show that the initial hydrogen absorption rate of the Pd/ZrCo composite film increased significantly [...] Read more.

In order to enhance the hydrogen absorption performance and poisoning resistance of ZrCo to O₂, Pd/ZrCo composite films were prepared by direct current magnetron sputtering. The results show that the initial hydrogen absorption rate of the Pd/ZrCo composite film increased significantly due to the catalytic effect of Pd compared with the ZrCo film. In addition, the hydrogen absorption properties of Pd/ZrCo and ZrCo were tested in poisoned hydrogen mixed with 1000 ppm O₂ at 10–300 °C, where the Pd/ZrCo films maintained a better resistance to O₂ poisoning below 100 °C. The mechanism of poisoning was investigated jointly by first-principles calculation combined with SEM-EDS elemental mapping tests. It is shown that the poisoned Pd layer maintained the ability to promote the decomposition of H₂ into hydrogen atoms and their rapid transfer to ZrCo. Full article

(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)

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21 pages, 4623 KiB  

Open AccessArticle

Fast Hydrogen Sorption Kinetics in Mg-VCl₃ Produced by Cryogenic Ball-Milling

by Karina Suárez-Alcántara, Nadia Isabel Flores-Jacobo, Mayara del Pilar Osorio-García and José Gerardo Cabañas-Moreno

Materials 2023, 16(6), 2526; https://doi.org/10.3390/ma16062526 - 22 Mar 2023

Cited by 6 | Viewed by 2164

Abstract

Hydrogen storage in Mg/MgH₂ materials is still an active research topic. In this work, a mixture of Mg-15wt.% VCl₃ was produced by cryogenic ball milling and tested for hydrogen storage. Short milling time (1 h), liquid N₂ cooling, and the [...] Read more.

Hydrogen storage in Mg/MgH₂ materials is still an active research topic. In this work, a mixture of Mg-15wt.% VCl₃ was produced by cryogenic ball milling and tested for hydrogen storage. Short milling time (1 h), liquid N₂ cooling, and the use of VCl₃ as an additive produced micro-flaked particles approximately 2.5–5.0 µm thick. The Mg-15wt.% VCl₃ mixture demonstrated hydrogen uptake even at near room-temperature (50 °C). Mg-15wt.% VCl₃ achieved ~5 wt.% hydrogen in 1 min at 300 °C/26 bar. The fast hydriding kinetics is attributed to a reduction of the activation energy of the hydriding reaction (E_{a hydriding} = 63.8 ± 5.6 kJ/mol). The dehydriding reaction occurred at high temperatures (300–350 °C) and 0.8–1 bar hydrogen pressure. The activation energy of the dehydriding reaction is 123.11 ± 0.6 kJ/mol. Cryomilling and VCl₃ drastically improved the hydriding/dehydriding of Mg/MgH₂. Full article

(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)

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12 pages, 4320 KiB  

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of KCl Addition on First Hydrogenation Kinetics of TiFe

by Joydev Manna and Jacques Huot

Compounds 2022, 2(4), 240-251; https://doi.org/10.3390/compounds2040020 - 6 Oct 2022

Cited by 4 | Viewed by 2286

Abstract

In this paper, the effect of the addition of potassium chloride (KCl) by ball milling on the first hydrogenation kinetics of TiFe is reported. After milling, KCl was uniformly distributed on the TiFe’s surface. As-synthesized TiFe does not absorb hydrogen. However, after ball [...] Read more.

In this paper, the effect of the addition of potassium chloride (KCl) by ball milling on the first hydrogenation kinetics of TiFe is reported. After milling, KCl was uniformly distributed on the TiFe’s surface. As-synthesized TiFe does not absorb hydrogen. However, after ball milling with KCl, it absorbed 1.5 wt.% of hydrogen on the first hydrogenation without any thermal treatment. The storage capacity of TiFe with KCl addition is higher than that of the ball milled pure TiFe. The effects of the amount of KCl additive in TiFe and ball milling time on first hydrogenation kinetics are reported. It is noted that, with an increase in KCl amount and ball milling time, hydrogenation kinetics are improved. However, hydrogen storage capacity decreased for both cases. Full article

(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)

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18 pages, 751 KiB  

Open AccessArticle

Investigation of the Hydrogen Absorption by the LaNi₅ and LaNi_4.75Pb_0.25 Alloys Using a Statistical Physics Model

by Michał Żurek and Wojciech Zając

Hydrogen 2022, 3(3), 361-378; https://doi.org/10.3390/hydrogen3030022 - 15 Sep 2022

Cited by 6 | Viewed by 2740

Abstract

A theoretical model was selected among three potentially applicable models and then used to analyze the absorption isotherms of the hydrogen storage alloys LaNi₅ and LaNi_4.75Pb_0.25 at three different temperatures (T = 303 K, 313 K, 323 K). The [...] Read more.

A theoretical model was selected among three potentially applicable models and then used to analyze the absorption isotherms of the hydrogen storage alloys LaNi₅ and LaNi_4.75Pb_0.25 at three different temperatures (T = 303 K, 313 K, 323 K). The theoretical expressions of the model were based on the statistical physics formalism and simplifying hypotheses. The model selected was the one with the highest correlation with the experimental data. The model had six adjustable parameters: the number of hydrogen atoms per site $n_{\alpha }$, $n_{\beta }$, the receptor site densities $N_{\alpha }$, $N_{\beta }$ and the energy parameters $P_{\alpha }$, $P_{\beta }$. The fitted parameters obtained for the Pb-doped and nondoped alloys were compared and discussed in relationship to the absorption isotherms. Finally, the fitted parameters or the model were further applied to calculate thermodynamic functions, such as entropy, Gibbs free energy and internal energy, which govern the absorption mechanism. Full article

(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)

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15 pages, 3404 KiB  

Open AccessArticle

Effect of Mn Element on the Structures and Properties of A₂B₇-Type La–Y–Ni-Based Hydrogen Storage Alloys

by Anqiang Deng, Yongchun Luo, Jianfei Zhou, Yunding Xie, Yuan Yuan, Xiaoyan Kang, Bingjin Shen and Haimin Zhang

Metals 2022, 12(7), 1122; https://doi.org/10.3390/met12071122 - 30 Jun 2022

Cited by 14 | Viewed by 2417

Abstract

The structures, hydrogen storage behaviors and electrochemical properties of Y_0.75La_0.25Ni_3.5−xMn_x (x = 0–0.3) alloys were analyzed by X-ray diffraction, Neutron powder diffraction, pressure–composition isotherms and electrochemical tests. All alloys have a multiphase structure. With [...] Read more.

The structures, hydrogen storage behaviors and electrochemical properties of Y_0.75La_0.25Ni_3.5−xMn_x (x = 0–0.3) alloys were analyzed by X-ray diffraction, Neutron powder diffraction, pressure–composition isotherms and electrochemical tests. All alloys have a multiphase structure. With the increase in Mn content, the Gd₂Co₇-type phase of the alloys gradually transforms into the Ce₂Ni₇-type phase; the Mn atom mainly occupies the Ni sites in the [AB₅] subunit and the interface between the [AB₅] and [A₂B₄] subunits; the V_[A2B4]/V_[AB5] continuously decreases from 1.045 (x = 0) to 1.019 (x = 0.3), which reduces the volume mismatch between [A₂B₄] and [AB₅] subunits. The maximum hydrogen absorption of the series alloys increases first and then decreases, and the addition of Mn effectively promotes the hydrogen absorption/desorption performance of the alloys. The maximum discharge capacity of the alloy electrodes is closely related to their hydrogen storage capacity at 0.1 MPa and hydrogen absorption/desorption plateau pressure. The cyclic stability of all the Mn-containing alloy electrodes is improved clearly compared to that of Mn-free alloy electrodes, because the volume mismatch between the [AB₅] and [A₂B₄] subunits of the alloys becomes smaller after the addition of Mn, which can improve the structural stability and reduce the corrosion of alloys during hydrogen absorption/desorption cycles. When the Mn content is between 0.1 and 0.15, the Ce₂Ni₇-type phase of the alloys has high abundance and the alloy electrodes exhibit excellent overall performance. Full article

(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)

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