Hydrogen Storage Properties Research Articles

Nanostructured light metal hydride: Fabrication strategies and hydrogen storage performance

Hydrogen can play an important role in the development of a sustainable energy system. However, storing hydrogen in a safe, efficient and economical manner remains a huge challenge. Light metal hydrides have attracted considerable attention for hydrogen storage owing to their high gravimetric and volumetric hydrogen densities. However, the strong covalent and/or ionic bonds between metal atoms and hydrogen result in slow kinetics, poor reversibility, and temperatures too high for dehydrogenation, hence delaying their practical large–scale applications. Considerable efforts have been toward tailoring the thermodynamic and kinetic properties of light metal hydride–based hydrogen storage materials for performance improvement, with the fabrication of nanoscale particles being a key and effective strategy. This review covers the preparation methods and hydrogen storage performance of nanostructured light metal hydrides. The physical and chemical properties and hydrogen storage behaviors of reversible light metal hydrides are first summarized, including MgH2, borohydrides, aluminum hydrides, amide–hydride systems, and hydride composites. The second section focuses on the research progress in nanostructuring for enhancing the reversible hydrogen storage properties of these hydrides. Finally, the main challenges and the future research prospects are discussed. The combination of nanostructuring and nanocatalysis can significantly enhance the performance of these hydrides and make them practical hydrogen carriers.

First-principles investigation for the hydrogen storage properties of XTiH3 (X=K, Rb, Cs) perovskite type hydrides

The perovskite-type hydride compounds are potential candidate materials in the field of hydrogen storage. This paper presents a systematical study of XTiH3 (X = K, Rb, Cs) using density functional theory. The analysis of formation energy, elastic properties and phonon dispersion curves indicate that all the studied materials are thermodynamically, mechanically and dynamically stable. By analyzing the B/G ratio, it is determined that these compounds are brittle materials. The electronic properties reveal that the XTiH3 compounds exhibit semi-metallic characteristics. The charge transfer characteristics of these compounds were analyzed using Bader partial charges. Moreover, the thermodynamic characteristics of these compounds were investigated and the dependence of their free energy, entropy and heat capacity on the temperature were analyzed. Finally, the gravimetric hydrogen storage capacities of KTiH3, RbTiH3 and CsTiH3 were calculated to be 3.36, 2.22 and 1.65 wt%, respectively. The hydrogen desorption temperatures of KTiH3, RbTiH3 and CsTiH3 were found to be 209 K, 161 K and 107 K, respectively. To our knowledge, this study represents the very first investigation of XTiH3 compounds and offers valuable references to this hydrogen storage material.

Hydrogen storage property improvement of ball-milled Mg2.3Y0.1Ni alloy with graphene

In this paper, Mg2.3Y0.1Ni + x wt.% graphene (x = 1, 3, 5, 7) composite hydrogen storage alloys were fabricated by mechanical ball milling of Mg2.3Y0.1Ni alloy powder and graphene. The experimental results show that the phases of the composite alloy consist mainly of Mg2Ni, Mg, MgNi2 and Ni3Y phases, and graphene tends to be distributed at the edges of the alloy, increasing the phase boundary resulting from the contact between the C-boundary and the Mg2.3Y0.1Ni alloy, providing more channels for the diffusion of H2. In which 7 wt.% of graphene is added, the gestation period of the composite alloy completely disappears. And the ball-milled alloy with 3 wt.% graphene at different temperatures has the highest hydrogen uptake in 2 min and the highest hydrogen release in 10 min. At 573 K, the composite alloy has a hydrogen absorption capacity of 3.251 wt.% H2 in 2 min and reaches 90.21% of the maximum hydrogen absorption, while it is able to release 3.389 wt.% H2 in 10 min and reaches 99.04% of the maximum hydrogen release. And the composite alloy with 3 wt.% graphene has the smallest dehydrogenation activation energy. The absolute value of the enthalpy change is reduced from 60.1 kJ/mol to 54.8 kJ/mol, and the desorption enthalpy change is reduced from 73.4 kJ/mol to 67.5 kJ/mol.

Investigation of structural, electronic, mechanical, optical and hydrogen storage properties of cobalt-based hydride-perovskites XCoH3 (X = In, Mn, Sr, Sn, Cd) for hydrogen storage application

In the current study, the physical and hydrogen storage properties of XCoH3 (X = In, Mn, Sr, Sn, Cd) are studied by using first principles calculations. The bandgap and lattice parameters of the studied materials match well with the previous studies involving cobalt-based hydride perovskites. All the compounds are found stable and possess metallic behavior with zero band gap. All the materials are found ductile except MnCoH3 and SrCoH3 which have brittle nature. The Bulk, Shear, and Youngs modulus suggest that CdCoH3 is harder than the other materials. The anisotropic factor suggests that all the materials possess anisotropic nature. The absorption coefficient shows that SrCoH3 is briskly in absorbing the incident photons. The reflectivity shows that SnCoH3 is an effective material for bouncing back the incident radiations. The other optical parameters such as refractive index, extinction coefficient, dielectric function, conductivity and loss function are also investigated in detail. The gravimetric hydrogen storage is found 1.71%, 2.59%, 2.03%, 1.68%, and 1.74 wt% for InCoH3, MnCoH3, SrCoH3, SnCoH3 and CdCoH3, respectively. Due to the higher gravimetric ratio, MnCoH3 is suggested as the most favorable material for storing hydrogen.

Improved hydrogen storage properties of low-cost Ti–Cr–V alloys by minor alloying of Mn

V-based BCC solid-solution alloys have been considered as promising hydrogen storage materials due to their high hydrogen storage capacity; however, the low effective hydrogen desorption capacity and high cost of pure V have limited their practical application in fuel cell vehicles or devices. Herein, a low-V TiCr1.2(V–Fe0.203)0.6 hydrogen storage alloy with a hydrogen storage capacity of 3.35 wt% has been developed by using a low-cost FeV80 as raw material. To further increase the effective hydrogen desorption capacity, cheap Mn is first used to partially substitute for Cr in FeV80-based alloy. The Mn substitution alloy achieves an effective hydrogen desorption capacity of 2.07 wt% cutting-off at 0.1 MPa with good activation performance. It is ascribed that the minor alloying of Mn increases the dehydrogenation plateau pressure and reduces the hysteresis and the enthalpy change value. The dehydrogenation enthalpy decreases from 34.84 kJ/mol to 31.51 kJ/mol. The synergistic effect of Mn and Fe increases the abundance of the C14 Laves phase, which plays a catalytic role in hydrogen absorption and desorption. The cost of TiCr1.1Mn0.1(V–Fe0.203)0.6 alloy is much lower than that of using pure V, and even lower than some AB2 alloys based on cost estimation. The results of this study would provide a reference for the application of low-cost Ti–Cr-(FeV80) alloys for hydrogen storage.

Enhanced electrochemical hydrogen storage properties of Ti49Zr26Ni25 quasicrystal alloy by doping with CO2-activated porous graphene

Ti49Zr26Ni25 quasicrystal alloy was fabricated via mechanical alloying and subsequent annealing. In order to enhance the electrocatalytic activity and conductivity of Ti49Zr26Ni25, the porous graphene (PoRGO) material was synthesized by a facile CO2 activation treatment of reduced graphene oxide (RGO). The composites of Ti49Zr26Ni25 doping with different amount of PoRGO were manufactured through ball milling. During the electrochemical hydrogen storage test, the porous Ti49Zr26Ni25 + PoRGO exhibited higher discharge capacity than Ti49Zr26Ni25 + CRGO and conventional Ti49Zr26Ni25 alloy. Moreover, the additive amount of PoRGO had great influence on the electrochemical properties of Ti49Zr26Ni25. Eventually, 5 wt% PoRGO modified Ti49Zr26Ni25 alloy electrode achieved a highest discharge capacity of 270 mAh/g. The large specific surface area and distinctive porous structure of porous graphene could offer more electrochemical active sites and facilitate the hydrogen diffusion. In the meantime, the cycling stability, high-rate dischargeability (HRD) and kinetic properties of Ti49Zr26Ni25 were also improved after PoRGO loading. Consequently, porous graphene can be potential used as the dopant for the modification of hydrogen storage alloys.

Microstructure and First Hydrogenation Properties of Ti16V60Cr24−xFex + 4 wt.% Zr Alloy for x = 0, 4, 8, 12, 16, 20, 24

In body-centered cubic (BCC) alloys of transition elements, elemental addition or substitution in the vanadium-based alloys can be beneficial for improving the hydrogen storage properties and for reducing the production cost. In this context, the current study focused on the effect of the substitution of Cr by Fe in Ti16V60Cr24−xFex + 4 wt.% Zr alloys where x = 0, 4, 8, 12, 16, 20, 24. The microstructure of each alloy was composed of a matrix having a chemical composition close to the nominal one and a Zr-rich region. From X-ray diffraction patterns, it was found that the matrix has a BCC structure, and the Zr-rich regions present the C14 Laves phase structure. The lattice parameter of BCC phases decreased linearly with x, in accordance with Vegard’s law. The measurement of the first hydrogenation at 298 K under 3 MPa of hydrogen revealed a decrease in the maximum hydrogen capacity: 3.8 wt.% for x = 0, 3.1 wt.% for x = 4 and around 2 wt.% for x = 8 to 24. The XRD patterns after hydrogenation showed a BCT phase for all alloys, with a C14 phase for x = 4, 8, 12 and with C14 and C15 for x = 16, 20 and 24.

Metal-organic Frameworks (MOFs) on Hydrogen Storage and Purification

As a clean energy source, hydrogen shows promise as a potential substitute for non-renewable fossil fuels. However, the challenges with hydrogen include the difficulties in storing it feasibly and separating it from other gases mixed during industrial production. Metal-organic frameworks (MOFs) refer to crystalline substances that possess a significant porosity and expansive surface area, enabling them to effectively adsorb hydrogen via the van der Waals force. MOFs have been studied for ways to improve their surface area and hydrogen uptake capacities by various modification methods. This review discusses the key strategies for enhancing the hydrogen storage properties of MOFs to achieve the necessary increase in energy supply and the mechanisms behind the purification of hydrogen in practical use. Detailed discussions take place regarding synthesis methods, experimental testing results, and the mechanism behind the enhancement of hydrogen storage for each modification of MOF material discovered. Also, other parameters that may influence MOFs’ hydrogen storage properties are demonstrated, together with the separating mechanism of purifying hydrogen from other gases and isotopes.

Advancements in Metal Hydride Materials for Hydrogen Storage

Hydrogen energy is attracting the attention of scientists because of its high energy density and low environmental pollution in the world trend of clean energy use. In addition, the basis for the use of hydrogen energy is its secure, cost-effective, and efficient storage. After decades of devotions by experts, many high-performance hydrogen storage materials have been created. The poor hydrogen storage capacity, challenging hydrogen storage circumstances, slow hydrogen storage speed, and potential safety concerns remain, nonetheless, with the present hydrogen storage materials. Metal hydride materials, which have a high hydrogen storage density and safe reactions, have so steadily been a research focus in recent years. In this paper, magnesium-based materials and titanium-based materials are selected as the representatives of metal hydride materials, and their hydrogen storage mechanisms, common modification methods, and the advanced research progress of these methods are reviewed. Through the analysis of data, the hydrogen storage properties and the respective characteristics of each modified hydrogen storage material are rigorously presented. The key technical limitations and possible improvement directions of these materials are summarized, and the future application prospects and development trends of hydrogen storage materials are predicted at the end.

Effect of interlayer and deposition temperature on the hydrogen storage properties of amorphous Mg-based thin films

In this work, the effect of different interlayers (including Mo, Nb, and Ti) and deposition temperatures (including 25 °C, 75 °C, 150 °C and 200 °C) on the hydrogen storage performance of MgNi amorphous alloy films are studied. On the one hand, the MgNi amorphous alloy films remain undestroyed after hydrogen absorption and desorption cycles with the help of Mo, Nb and Ti interlayers. However, the onset desorption temperature and peak desorption temperature of the MgNi amorphous alloy films are almost unchanged after inserting the interlayers. On the other hand, as the deposition temperature increases from 25 °C to 200 °C, there are nanocrystalline Mg2Ni and Mg phases formed in the amorphous MgNi alloy matrix. The crystalline-amorphous structure provides abundant nucleation sites for hydride formation, and accelerate the diffusion and dissociation of hydrogen.

Synergistic effect for improving the hydrogen storage capability and electrochemical performance of AB2 Laves phase alloys

The structure of a series AB2 Laves-type metal hydride alloys, in which Ce was doped into Ti0.24Zr0.76Ni1.15Mn0.7V0.15 and annealed the alloys, was studied and correlated to hydrogen storage properties and electrochemical performances. X-ray diffraction, scanning electron microscope, and energy-dispersive spectroscopy results revealed that Ce formed a CeNi3 secondary phase instead of entering the Laves phases. The synergistic effect of the CeNi3 and (Ti,Zr)Ni phase improved the hydrogen storage and electrochemical discharge properties of the Ce-doped (Ce0.02) alloy. Especially, the secondary phases could decrease the hydrogen absorption plateau, reduce the hysteresis phenomenon, and increase the hydrogen storage capacity (from 0.9 wt% to 1.4 wt% at 25 ℃). The formation of CeNi3Hx hydride on the surfaces of alloy electrodes led to a higher discharge capacity (∼500 mAh/g) and a faster activation rate. The Ce0.02 alloy also showed a good cyclic stability ∼82.08%, after 500 charge-discharge cycling, which could be ascribed to the good corrosion resistance of the CeNi3 phase on the surface of alloy. In addition, annealing treatment promoted the depletion of (Ti,Zr)Ni secondary phase and the transformation from the C14 to C15 phase. The Ce-doped AB2 alloy can be used as a hydrogen storage and hydride battery electrode material.

The performance of Li-modified B-doped phagraphene as a reversible hydrogen storage material in near-environmental conditions

In recent years, various applications of two-dimensional carbon nanomaterial phagraphene, whose protocells contain 5, 6 and 7 carbon rings, have been investigated. In this paper, first-principles and Grand Canonical Monte Carlo (GCMC) simulation methods are used to study the hydrogen storage properties of primitive and B-doped lithium modified phagraphene. The DFT results show that the binding energy of lithium atoms in Li-phagraphene is 2.0 eV. After B doping, the binding energy was significantly increased to 2.8 eV, and the molecular weight ratio of hydrogen was 13.07 wt%. According to the calculation of GCMC, the hydrogen storage weight ratio could reach 6.36 wt% under the environmental conditions of 298 K and 1 bar. The calculated Van't Hoff equation shows that doping B is more conducive to hydrogen desorption at atmospheric pressure. These results indicate that Li-modified B-doped phagraphene is a candidate material for realizing reversible hydrogen storage in near-environmental conditions.

The Effect of Severe Plastic Deformation on the Hydrogen Storage Properties of Metal Hydrides

Solid-state hydrogen storage in various metal hydrides is among the most promising and clean way of storing energy, however, some problems, such as sluggish kinetics and high dehydrogenation temperature should be dealt with. In the present paper the advances of severe plastic deformation on the hydrogenation performance of metal hydrides will be reviewed. Techniques, like high-pressure torsion, equal-channel angular pressing, cold rolling, fast forging and surface modification have been widely applied to induce lattice defects, nanocrystallization and the formation of abundant grain boundaries in bulk samples and they have the potential to up-scale material production. These plastically deformed materials exhibit not only better H-sorption properties than their undeformed counterparts, but they possess better cycling performance, especially when catalysts are mixed with the host alloy promoting potential future applications.

Tailoring hydrogenation and anti-oxidation properties of titanium - iron - chromium alloys by regulating zirconium content at room temperature

The effects of Fe substitution by Zr on the microstructure, hydrogen storage properties and oxidation resistance of the TiFe0.85-xCr0.15Zrx (x = 0, 0.05, 0.10, 0.15) alloys are studied in this work. It is shown that all the alloys are consisted of TiFe phase, MgZn2-type phase and minor Ti phase. The introduction of Zr causes no change for the TiFe main phase. All the alloys absorb hydrogen directly under mild conditions without any activation process. As Zr content increases, the maximum hydrogen storage capacity of the first hydrogenation increases while the reversible hydrogen storage capacity decreases. The marked change of the first hydrogenation properties may be due to the formation of the bright phase (MgZn2-type phase). The decrease of the reversible hydrogen storage capacity is due to the formation of the stable hydrides Cr2ZrH3 and TiH2, which start to decompose at around 700 °C. During the air exposure test, the alloys with higher Zr content show good oxidation resistance. For the PCT measurement, the alloys with higher Zr show lower hydrogen absorption and desorption platform pressure, which means more stable hydrides are formed during the first hydrogenation. Moreover, the rate limiting step model of the first and fifth hydrogenation processes of all the alloys has also been investigated in detail.

Hydrangea-like NiO@KNbO3 as catalyst doping for MgH2: Boosting hydrogen storage performance

MgH2 is regarded as one of the most favorable materials for hydrogen storage caused by its safety, high efficiency, considerable capacity for storing hydrogen, and low cost. However, the application of this material is limited owing to subpar thermodynamics and kinetics, which can be improved via combination with other materials. A hydrangea-like NiO@KNbO3 was prepared by solvent thermal, hydrothermal, and calcination methods. Then, different amounts of NiO@KNbO3 (3, 5, 7, and 10 wt %) were added to MgH2 using ball-milling. MgH2 composite material doped with 5 wt % NiO@KNbO3 exhibits the most superior hydrogen storage performance, with a hydrogen absorption capacity of 4.95 wt % H2 within 5 min at 150 ℃ and 1.5 MPa H2 pressure. Furthermore, H2 release started approximately at 175 °C with 5.96 wt % H2 at 300 °C. The composite's H2 desorption activation energy was decreased to 71.75 kJ/mol. The Mg2NiH4/Mg2Ni generated in situ can serve as a "hydrogen pump" by creating numerous activation sites and pathways for hydrogen diffusion, thereby facilitating H2 dissociation during the process of hydrogen absorption. Additionally, the NiO@KNbO3-doped MgH2 samples exhibited excellent integrated hydrogen storage properties due to the combined effect of KNbO3 and the in situ formed NbO. The study provides clear evidence that NiO@KNbO3, a bimetallic oxide, can effectively enhance the hydrogen storage performance of MgH2 as an additive. Furthermore, the straightforward synthesis of NiO@KNbO3 offers guidance for the development of high-performance oxide catalysts that can improve the properties of MgH2.

Influence of TiF3 catalyst on the enhancement of hydrogen storage properties of Mg-Na-Al-Li-B composite system

This study emphasizes the catalytic function of TiF3 on hydrogen storage properties and the reaction mechanism of the MgH2-Na3AlH6-LiBH4 produced by employing the ball-milling technique, which has a molar ratio of 1:1:4. It discovered that the mixture of Na3AlH6 and LiBH4 reacted through a metathesis reaction and transformed into Li3AlH6 and NaBH4 composite upon the ball milling procedure. MgH2-Li3AlH6-NaBH4 destabilized system with TiF3 catalyst has displayed four decomposition tiers throughout the heating procedure. The initial tier of hydrogen release in the composite occurs at temperatures of 100 °C and 75 °C lower than in the catalyst-free composite. Continuous heating resulted in two through four dehydrogenation tiers, with an overall capacity of 10.1 wt% hydrogens released (at temperatures of 200 °C, 350 °C, and 400 °C, respectively). In contrast to the Mg-Na-Al-Li-B-H catalyst-free composite, incorporating the TiF3 catalyst demonstrates a faster hydrogen uptake and release rate. The apparent activation energy (Ea) for the dissociation of Li3AlH6, MgH2, and NaBH4 in the composite with TiF3 catalyst was remarkably abridged compared to the catalyst-free ternary system (Kissinger plot; 23, 20, and 13 kJ/mol, respectively for doped composite). TiF3's considerable catalytic performance is ascribed to the in-situ production of AlTi and AlF phases during the dehydrogenation process of TiF3 and Li3AlH6. Once generated, the AlTi and AlF phase serves as a genuine catalyst in the MgH2-Na3AlH6-4LiBH4-TiF3 ternary system.

Structures and bonding natures of tin- and zirconium-aluminum hydrides

With hydrogen contents 6.69 and 7.49 wt%, Sn(AlH4)4 and Zr(AlH4)4 were experimentally synthesized, but their structures, bonding natures and hydrogen storage properties were not further investigated. This paper determines the low energy structures of Sn(AlH4)4 and Zr(AlH4)4 crystals by using global optimization algorithm combined with density functional theories, and analyze their electronic structures and bonding properties. The most stable structures of Sn(AlH4)4 and Zr(AlH4)4 contain isolated H2 molecules. The formation enthalpies of Zr(AlH4)4 reaches 1.0 eV and the value of Sn(AlH4)4 is a little smaller. In Zr(AlH4)4, the AlH5, AlH6 and Al2H6 units are connected tightly by Zr atoms through H bridges. In Sn(AlH4)4, the AlH6 units form a net structure, and the Sn atom exists in SnH3 with one shared H atom. The bonding characteristics are analyzed by calculating charge populations and crystal orbital hamilton population (COHP). The metal components (Al, Sn, Zr) and H atoms form polarized covalent bonds. The covalent contributions are close for Sn–H and Al–H bonds but the charge values on the Sn atoms are much smaller. For the Zr–H bonds, both the charges on the Zr atoms and the covalent contributions are smaller than the values of the Al–H bonds. Combining the bonding natures and the structure features, it suggests that proper electronegativity of the metal atoms (Sn and Zr here) is the key factor for the stabilities and reversible hydrogen storage properties of metal aluminum hydrides.

Calcium-Decorated Polygon-Graphenes for Hydrogen Storage

We performed first-principles calculations to investigate hydrogen (H2) storage properties of bare and calcium (Ca)-decorated polygon-graphenes, i.e., biphenylene and ψ-graphene monolayers consisting of polygons, from tetragons to octagons. In pristine forms, both biphenylene and ψ-graphene bind H2 weakly. However, upon Ca doping, biphenylene adsorbed up to five H2 molecules regardless of polygonal sites, whereas ψ-graphene anchored up to six and five H2 molecules to pentagonal and heptagonal sites, respectively. In all the cases, the H2 binding energy was ∼0.30 eV, enabling reversible room-temperature H2 storage. The H2 storage capacity can reach ∼6.8 and ∼4.2 wt % for Ca-decorated biphenylene and ψ-graphene, respectively. Using equilibrium thermodynamics, we showed the adsorption and desorption of H2 at 300 and 380 K under ambient pressure, respectively. This clearly indicates that Ca-decorated 2D sp2 carbon sheets with polygons (biphenylene, ψ-graphene) could be used as promising H2 storage materials.

Enhancement of hydrogen storage properties of NaAlH4 catalyzed by CuFe2O4

This study describes the hydrogen storage performance of NaAlH4 with the addition of CuFe2O4 additive. The results were compared with undoped NaAlH4. For the first and second steps of dehydrogenation, the CuFe2O4-doped NaAlH4 liberated hydrogen at 150 °C and 220 °C, whereas as-milled NaAlH4 released hydrogen at 190 °C and 290 °C, respectively. The desorption kinetic analysis unveiled that the doped system liberated around 1.5 and 4.4 wt% hydrogen within 120 min at 150 and 200 °C, respectively. Meanwhile, the undoped NaAlH4 only desorbed 0.5 and 3.6 wt% hydrogen, respectively, under identical conditions. The activation energy for the doped system at the first step of dehydrogenation was decreased from 114.7 to 92.5 kJ/mol, while reduced from 125.2 to 98.1 kJ/mol at the second stage. The synergistic impact between the in-situ formed Cu2O and Fe during the heating process indicated that these active species are superior in boosting the hydrogen storage performance of NaAlH4.

Hydrogen storage and electrochemical properties of 3R- and 2H-A5B19 structures in La-Y-Ni-based alloys

The A5B19 phase of La-Y-Ni-based alloys presents two isomers of 2H and 3R phase due to the different A2B4 subunits. In this work, the hydrogen storage, and electrochemical properties of A5B19-type LaY2Ni10.6Mn0.5Al0.3 alloys with different 2H and 3R content is investigated. The results show that 2H- and 3R-A5B19 phases have comparable hydrogen storage and electrochemical properties but different structural stability during cycling, which is caused by the volume difference (∆V) between A2B4 and AB5 subunits during hydrogen absorption process. Compared with 3R-A5B19 phase, the smaller volume expansion of A2B4 subunits of 2H-A5B19 phase after cycling leads to a smaller ∆V, and therefore, better structural/cycling stability. Furthermore, the alloys composed by the two phases present a high-rate discharge ability (HRD) of ca. 76 % as well as a discharge capacity of 265 mAh/g at a discharge current density of 1500 mA/g, demonstrating the potential applications of La-Y-Ni alloy in high-power nickel-metal hydride battery.