Metal Hydrogen Systems: Fundamental Properties and Current Applications for Energy Storage and Conversion

A special issue of Inorganics (ISSN 2304-6740).

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 29244

Special Issue Editor


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Guest Editor
1. RCB Hydrides, LLC, Franklin, OH 45005, USA
2. Jet Propulsion Laboratory (Retired), Pasadena, CA, USA
3. Oak Ridge National Laboratory (Retired), Oak Ridge, TN, USA
Interests: metal-hydrogen systems; Nuclear Magnetic Resonance; hydrogen storage and energy conversion materials; isotope effects; reaction mechanisms of metal hydrides; kinetics and diffusion properties

Special Issue Information

Dear colleagues,

The reactions of metals, alloys, and intermetallics with hydrogen either directly or electrochemically lead to a plethora of interesting and useful materials called metal hydrides.  Not only do metal hydrides exhibit fascinating intrinsic behavior with respect to their phase transitions, diffusion processes, and crystal structure transformations, but they also have been extensively utilized in the chemical and nuclear industries as well as in numerous niche applications for decades due to their unique chemistries and physical properties.  With the advent of increasing reliance on hydrogen fuel cells for environmentally cleaner transportation and stationary energy storage systems along with development of diverse thermal energy and electrochemical devices including advanced batteries, hydrides will continue to be major contributors to these technologies and their supporting infrastructures in the future.

You are invited to submit manuscripts that report original research results or provide insightful reviews on the properties and applications for all varieties of metal-hydrogen materials. Fundamental aspects related to reaction mechanisms and the roles of catalysts and nanoconfinement evaluated via theoretical and experimental approaches as well as the description and modelling of the diverse range of hydrides in energy storage and conversion technologies are welcome.

Dr. Robert C. Bowman, Jr.
Guest Editor

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Keywords

  • metal hydrides
  • complex and ionic hydrides
  • hydrogen storage and compression
  • hydrides for rechargeable batteries (solid electrolytes and electrodes)
  • catalysts and reaction mechanisms
  • hydrides of high-entropy alloys
  • nanocomposite and confined hydride systems
  • engineering applications of hydrides
  • modelling and simulations
  • energy storage and conversion
  • hydrogen infrastructure

Published Papers (11 papers)

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Research

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11 pages, 3644 KiB  
Article
Entropy-Enthalpy Compensation in Ti-V-Mn-Cr BCC Alloys Used as Hydrogen Storage Materials
by Chourouk Kefi and Jacques Huot
Inorganics 2023, 11(12), 479; https://doi.org/10.3390/inorganics11120479 - 14 Dec 2023
Viewed by 1183
Abstract
In this paper, we report the effect of the Cr/Mn ratio on the thermodynamic properties of Ti30V60Mn(10−x)Crx (x = 0, 3.3, 6.6 and 10) + 4 wt.% Zr alloys. It was found that the enthalpy and [...] Read more.
In this paper, we report the effect of the Cr/Mn ratio on the thermodynamic properties of Ti30V60Mn(10−x)Crx (x = 0, 3.3, 6.6 and 10) + 4 wt.% Zr alloys. It was found that the enthalpy and entropy change with the Cr/MN ratio and that the entropy and entropy variation is coupled in an enthalpy-entropy compensation fashion. Using a compensation quality factor, it was established that the enthalpy-entropy compensation is not due to a statistical origin, with a confidence of more than 95%. Full article
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18 pages, 3078 KiB  
Article
Tailoring of Hydrogen Generation by Hydrolysis of Magnesium Hydride in Organic Acids Solutions and Development of Generator of the Pressurised H2 Based on this Process
by Mykhaylo V. Lototskyy, Moegamat Wafeeq Davids, Tshepo Kgokane Sekgobela, Artem A. Arbuzov, Sergey A. Mozhzhukhin, Yongyang Zhu, Renheng Tang and Boris P. Tarasov
Inorganics 2023, 11(8), 319; https://doi.org/10.3390/inorganics11080319 - 27 Jul 2023
Cited by 4 | Viewed by 1268
Abstract
Hydrolysis of light metals and hydrides can potentially be used for the generation of hydrogen on-board fuel cell vehicles, or, alternatively, for refilling their fuel tanks with H2 generated and pressurised without compressor on site, at near-ambient conditions. Implementation of this approach [...] Read more.
Hydrolysis of light metals and hydrides can potentially be used for the generation of hydrogen on-board fuel cell vehicles, or, alternatively, for refilling their fuel tanks with H2 generated and pressurised without compressor on site, at near-ambient conditions. Implementation of this approach requires solution of several problems, including the possibility of controlling H2 release and avoiding thermal runaway. We have solved this problem by developing the apparatus for the controlled generation of pressurised H2 using hydrolysis of Mg or MgH2 in organic acid solutions. The development is based on the results of experimental studies of MgH2 hydrolysis in dilute aqueous solutions of acetic, citric, and oxalic acids. It was shown that the hydrogen yield approaches 100% with a fast hydrolysis rate when the molar ratio acid/MgH2 exceeds 0.9, 2.0, and 2.7 for the citric, oxalic, and acetic acids, respectively. In doing so, the pH of the reaction solutions after hydrolysis corresponds to 4.53, 2.11, and 4.28, accordingly, testifying to the buffer nature of the solutions “citric acid/magnesium citrate” and “acetic acid/magnesium acetate”. We also overview testing results of the developed apparatus where the process rate is effectively controlled by the control of the acid concentration in the hydrolysis reactor. Full article
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10 pages, 2212 KiB  
Article
Metal Hydride Hydrogen Storage (Compression) Units Operating at Near-Atmospheric Pressure of the Feed H2
by Boris Tarasov, Artem Arbuzov, Sergey Mozhzhukhin, Aleksey Volodin, Pavel Fursikov, Moegamat Wafeeq Davids, Joshua Adeniran and Mykhaylo Lototskyy
Inorganics 2023, 11(7), 290; https://doi.org/10.3390/inorganics11070290 - 06 Jul 2023
Cited by 1 | Viewed by 1162
Abstract
Metal hydride (MH) hydrogen storage and compression systems with near-atmospheric H2 suction pressure are necessary for the utilization of the low-pressure H2 produced by solid oxide electrolyzers or released as a byproduct of chemical industries. Such systems should provide reasonably high [...] Read more.
Metal hydride (MH) hydrogen storage and compression systems with near-atmospheric H2 suction pressure are necessary for the utilization of the low-pressure H2 produced by solid oxide electrolyzers or released as a byproduct of chemical industries. Such systems should provide reasonably high productivity in the modes of both charge (H2 absorption at PL ≤ 1 atm) and discharge (H2 desorption at PH = 2–5 atm), which implies the provision of H2 equilibrium pressures Peq < PL at the available cooling temperature (TL = 15–20 °C) and, at the same time, Peq > PH when heated to TH = 90–150 °C. This work presents results of the development of such systems based on AB5-type intermetallics characterized by Peq of 0.1–0.3 atm and 3–8 atm for H2 absorption at TL = 15 °C and H2 desorption at TH = 100 °C, respectively. The MH powders mixed with 1 wt.% of Ni-doped graphene-like material or expanded natural graphite for the improvement of H2 charge dynamics were loaded in a cylindrical container equipped with internal and external heat exchangers. The developed units with a capacity of about 1 Nm3 H2 were shown to exhibit H2 flow rates above 10 NL/min during H2 charge at ≤1 atm when cooled to ≤20 °C with cold water and H2 release at a pressure above 2 and 5 atm when heated to 90 and 120 °C with hot water and steam, respectively. Full article
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13 pages, 3049 KiB  
Article
Exploring the Hydrogen Sorption Capabilities of a Novel Ti-V-Mn-Zr-Nb High-Entropy Alloy
by Anis Bouzidi, Loïc Perrière, Erik Elkaim, Laetitia Laversenne, Vivian Nassif, Gavin Vaughan and Claudia Zlotea
Inorganics 2023, 11(5), 186; https://doi.org/10.3390/inorganics11050186 - 25 Apr 2023
Viewed by 1235
Abstract
Hydrogen is considered as a clean energy carrier able to achieve the decarbonization of the economy, but its compact, safe, and efficient storage represents an important challenge. Among many materials forming hydrides, this work reports the study of hydrogen sorption properties of a [...] Read more.
Hydrogen is considered as a clean energy carrier able to achieve the decarbonization of the economy, but its compact, safe, and efficient storage represents an important challenge. Among many materials forming hydrides, this work reports the study of hydrogen sorption properties of a novel bcc high-entropy alloy, Ti0.30V0.25Mn0.10Zr0.10Nb0.25, synthesized by arc melting. In less than 60 s, the alloy fully absorbs hydrogen at room temperature, reaching a capacity of 2.0 H/M (2.98 wt.%). A two-step reaction with hydrogen is confirmed by pressure-composition isotherms, synchrotron X-ray and neutron diffraction: bcc solid solution ↔ bcc monohydride ↔ fcc dihydride. For the second step transformation, the calculated thermodynamic values indicate the formation of a very stable dihydride, with ΔHabs = −97 kJ/molH2. Moreover, the pair distribution function analysis of high-energy synchrotron X-ray scattering data validates a completely random distribution of metal atoms in the fcc dihydride phase, without noticeable lattice strain nor elemental segregation. In situ synchrotron X-ray and neutron diffraction, performed during hydrogen desorption by heating under vacuum, demonstrated full reversibility of the reaction with hydrogen. On the basis of these results, tuning the chemical composition of high-entropy alloys may have great implications in terms of hydrogen sorption properties. Full article
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21 pages, 3779 KiB  
Article
Characterizing the ZrBe2Hx Phase Diagram via Neutron Scattering Methods
by Hui Wu, Wei Zhou, Terrence J. Udovic, Robert C. Bowman, Jr. and Bjørn C. Hauback
Inorganics 2023, 11(1), 1; https://doi.org/10.3390/inorganics11010001 - 20 Dec 2022
Cited by 1 | Viewed by 1252
Abstract
Since the initial assessment four decades ago of zirconium diberyllide, ZrBe2, as a potential hydride-forming intermetallic for hydrogen-storage applications, structural and dynamical studies to date have been chiefly limited to the hydride composition, ZrBe2H1.5, which exists as [...] Read more.
Since the initial assessment four decades ago of zirconium diberyllide, ZrBe2, as a potential hydride-forming intermetallic for hydrogen-storage applications, structural and dynamical studies to date have been chiefly limited to the hydride composition, ZrBe2H1.5, which exists as a single-phase disordered hydride with hexagonal P6/mmm symmetry that undergoes hydrogen sublattice ordering below ~200 K (~235–250 K for ZrBe2D1.5). It is desirable from both fundamental and technological viewpoints to have a more complete understanding of the ZrBe2Hx phase diagram. In the present study, both neutron powder diffraction and neutron vibrational spectroscopy measurements of ZrBe2Hx at lower hydrogen contents (x < 1.5) indicate that at least two other ordered phases exist at low temperatures, coinciding with respective nominal x values of 1 and 0.67. Compared to ZrBe2H1.5, these more-hydrogen-dilute phases possess different structural symmetries (orthorhombic) with different H-sublattice orderings and undergo much-higher-temperature order-disorder transitions at ≈ 460 K (x = 1) and ≈ 490 K (x = 0.67) to the characteristic H-disordered hexagonal P6/mmm structure associated with ZrBe2H1.5. Full article
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9 pages, 605 KiB  
Article
Effects of Glymes on the Distribution of Mg(B10H10) and Mg(B12H12) from the Thermolysis of Mg(BH4)2
by Ba L. Tran, Tamara N. Allen, Mark E. Bowden, Tom Autrey and Craig M. Jensen
Inorganics 2021, 9(6), 41; https://doi.org/10.3390/inorganics9060041 - 23 May 2021
Cited by 9 | Viewed by 2430
Abstract
We examined the effects of concentrations and identities of various glymes, from monoglyme up to tetraglyme, on H2 release from the thermolysis of Mg(BH4)2 at 160–200 °C for 8 h. 11B NMR analysis shows major products of Mg(B [...] Read more.
We examined the effects of concentrations and identities of various glymes, from monoglyme up to tetraglyme, on H2 release from the thermolysis of Mg(BH4)2 at 160–200 °C for 8 h. 11B NMR analysis shows major products of Mg(B10H10) and Mg(B12H12); however, their relative ratio is highly dependent both on the identity and concentration of the glyme to Mg(BH4)2. Selective formation of Mg(B10H10) was observed with an equivalent of monoglyme and 0.25 equivalent of tetraglyme. However, thermolysis of Mg(BH4)2 in the presence of stoichiometric or greater equivalent of glymes can lead to unselective formation of Mg(B10H10) and Mg(B12H12) products or inhibition of H2 release. Full article
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11 pages, 27148 KiB  
Article
A New Complex Borohydride LiAl(BH4)2Cl2
by Oleksandr Dolotko, Takeshi Kobayashi, Ihor Z. Hlova, Shalabh Gupta and Vitalij K. Pecharsky
Inorganics 2021, 9(5), 35; https://doi.org/10.3390/inorganics9050035 - 04 May 2021
Viewed by 2207
Abstract
A new mixed alkali metal–aluminum borohydride LiAl(BH4)2Cl2 has been prepared via mechanochemical synthesis from the 2LiBH4–AlCl3 mixture. Structural characterization, performed using a combination of X-ray powder diffraction and solid-state NMR methods, indicates that the LiAl(BH [...] Read more.
A new mixed alkali metal–aluminum borohydride LiAl(BH4)2Cl2 has been prepared via mechanochemical synthesis from the 2LiBH4–AlCl3 mixture. Structural characterization, performed using a combination of X-ray powder diffraction and solid-state NMR methods, indicates that the LiAl(BH4)2Cl2 phase adopts a unique 3D framework and crystallizes in an orthorhombic structure with the space group C2221, a = 11.6709(6) Å, b = 8.4718(4) Å, c = 7.5114(3) Å. The material shows excellent dehydrogenation characteristics, where hydrogen evolution starts at Tons = 70 °C, releasing approximately 2 wt.% of nearly pure (99.8 vol.%) hydrogen and a very small amount (~0.2 vol.%) of diborane. When compared to halide-free mixed alkali metal–aluminum borohydrides, the presence of Al‒Cl bonding in the LiAl(BH4)2Cl2 structure likely prevents the formation of Al(BH4)3 upon decomposition, thus suppressing the formation of diborane. Full article
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14 pages, 2649 KiB  
Article
Study of Anharmonicity in Zirconium Hydrides Using Inelastic Neutron Scattering and Ab-Initio Computer Modeling
by Jiayong Zhang, Yongqiang Cheng, Alexander I. Kolesnikov, Jerry Bernholc, Wenchang Lu and Anibal J. Ramirez-Cuesta
Inorganics 2021, 9(5), 29; https://doi.org/10.3390/inorganics9050029 - 21 Apr 2021
Cited by 3 | Viewed by 2560
Abstract
The anharmonic phonon behavior in zirconium hydrides and deuterides, including ϵ-ZrH2, γ-ZrH, and γ-ZrD, has been investigated from aspects of inelastic neutron scattering (INS) and lattice dynamics calculations within the framework of density functional theory (DFT). The harmonic model failed to [...] Read more.
The anharmonic phonon behavior in zirconium hydrides and deuterides, including ϵ-ZrH2, γ-ZrH, and γ-ZrD, has been investigated from aspects of inelastic neutron scattering (INS) and lattice dynamics calculations within the framework of density functional theory (DFT). The harmonic model failed to reproduce the spectral features observed in the experimental data, indicating the existence of anharmonicity in those materials and the necessity of further explanations. Here, we present a detailed study on the anharmonicity in zirconium hydrides/deuterides by exploring the 2D potential energy surface of hydrogen/deuterium atoms and solving the corresponding 2D single-particle Schrödinger equation to obtain the eigenfrequencies, which are then convoluted with the instrument resolution. The convoluted INS spectra qualitatively describe the anharmonic peaks in the experimental INS spectra and demonstrate that the anharmonicity originates from the deviations of hydrogen potentials from quadratic behavior in certain directions; the effects are apparent for the higher-order excited vibrational states, but small for the ground and first excited states. Full article
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Review

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25 pages, 7383 KiB  
Review
Volumetrics of Hydrogen Storage by Physical Adsorption
by Sai Smruti Samantaray, Seth T. Putnam and Nicholas P. Stadie
Inorganics 2021, 9(6), 45; https://doi.org/10.3390/inorganics9060045 - 04 Jun 2021
Cited by 19 | Viewed by 6034
Abstract
Physical adsorption remains a promising method for achieving fast, reversible hydrogen storage at both ambient and cryogenic conditions. Research in this area has recently shifted to focus primarily on the volumetric (H2 stored/delivered per volume) gains achieved within an adsorptive storage system [...] Read more.
Physical adsorption remains a promising method for achieving fast, reversible hydrogen storage at both ambient and cryogenic conditions. Research in this area has recently shifted to focus primarily on the volumetric (H2 stored/delivered per volume) gains achieved within an adsorptive storage system over that of pure H2 compression; however, the methodology for estimating a volumetric stored or delivered amount requires several assumptions related to the ultimate packing of the adsorbent material into an actual storage system volume. In this work, we critically review the different assumptions commonly employed, and thereby categorize and compare the volumetric storage and delivery across numerous different porous materials including benchmark metal-organic frameworks, porous carbons, and zeolites. In several cases, there is a significant gain in both storage and delivery by the addition of an adsorbent to the high-pressure H2 storage system over that of pure compression, even at room temperature. Lightweight, low-density materials remain the optimal adsorbents at low temperature, while higher density, open metal-containing frameworks are necessary for high-density room temperature storage and delivery. Full article
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20 pages, 18943 KiB  
Review
Scaling up Metal Hydrides for Real-Scale Applications: Achievements, Challenges and Outlook
by Emil H. Jensen, Martin Dornheim and Sabrina Sartori
Inorganics 2021, 9(5), 37; https://doi.org/10.3390/inorganics9050037 - 07 May 2021
Cited by 4 | Viewed by 3656
Abstract
As the world evolves, so does the energy demand. The storage of hydrogen using metal hydrides shows great promise due to the ability to store and deliver energy on demand while achieving higher volumetric density and safer storage conditions compared with traditional storage [...] Read more.
As the world evolves, so does the energy demand. The storage of hydrogen using metal hydrides shows great promise due to the ability to store and deliver energy on demand while achieving higher volumetric density and safer storage conditions compared with traditional storage options such as compressed gas or liquid hydrogen. Research is typically performed on lab-sized samples and tanks and shows great potential for large scale applications. However, the effects of scale-up on the metal hydride’s performance are relatively less investigated. Studies performed so far on both materials, and hydride-based storage tanks show that the scale-up can significantly impact the system’s capacity, kinetics, and sorption properties. The findings presented in this review suggest areas of further investigation in order to implement metal hydrides in real scale applications. Full article
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27 pages, 4930 KiB  
Review
Roles of Ti-Based Catalysts on Magnesium Hydride and Its Hydrogen Storage Properties
by Chengshang Zhou, Jingxi Zhang, Robert C. Bowman, Jr. and Zhigang Zak Fang
Inorganics 2021, 9(5), 36; https://doi.org/10.3390/inorganics9050036 - 06 May 2021
Cited by 24 | Viewed by 4649
Abstract
Magnesium-based hydrides are considered as promising candidates for solid-state hydrogen storage and thermal energy storage, due to their high hydrogen capacity, reversibility, and elemental abundance of Mg. To improve the sluggish kinetics of MgH2, catalytic doping using Ti-based catalysts is regarded [...] Read more.
Magnesium-based hydrides are considered as promising candidates for solid-state hydrogen storage and thermal energy storage, due to their high hydrogen capacity, reversibility, and elemental abundance of Mg. To improve the sluggish kinetics of MgH2, catalytic doping using Ti-based catalysts is regarded as an effective approach to enhance Mg-based materials. In the past decades, Ti-based additives, as one of the important groups of catalysts, have received intensive endeavors towards the understanding of the fundamental principle of catalysis for the Mg-H2 reaction. In this review, we start with the introduction of fundamental features of magnesium hydride and then summarize the recent advances of Ti-based additive doped MgH2 materials. The roles of Ti-based catalysts in various categories of elemental metals, hydrides, oxides, halides, and intermetallic compounds were overviewed. Particularly, the kinetic mechanisms are discussed in detail. Moreover, the remaining challenges and future perspectives of Mg-based hydrides are discussed. Full article
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