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Highlights Hydrogen storage performance of V-Ti-based solid solution alloys is related to the elementary composition, phase structure, and homogeneity. Micro-strain accumulation is responsible for capacity degradation. Low-cost and high-performance V-Ti-based solid solution alloys with high reversible hydrogen storage capacity, good cyclic durability, and excellent activation performance should be developed. This review details the advancement in the development of V–Ti-based hydrogen storage materials for using in metal hydride (MH) tanks to supply hydrogen to fuel cells at relatively ambient temperatures and pressures. V–Ti-based solid solution alloys are excellent hydrogen storage materials among many metal hydrides due to their high reversible hydrogen storage capacity which is over 2 wt% at ambient temperature. The preparation methods, structure characteristics, improvement methods of hydrogen storage performance, and attenuation mechanism are systematically summarized and discussed. The relationships between hydrogen storage properties and alloy compositions as well as phase structures are discussed emphatically. For large-scale applications on MH tanks, it is necessary to develop low-cost and high-performance V–Ti-based solid solution alloys with high reversible hydrogen storage capacity, good cyclic durability, and excellent activation performance.

We present a detailed computational investigation of the structural, optical, mechanical, and hydrogen storage properties of Cs 2 XAlH 6 (X = K, Na and Rb) double perovskite hydrides. All compounds crystallize in a cubic structure, with lattice parameters influenced by the ionic radius of the X-site cation. Electronic structure calculations reveal an indirect band gap, supporting the materials stability. Hydrogen storage analysis indicates thermodynamic stability, efficient desorption temperatures, and high storage capacities, particularly for lighter cations like Na. Optical properties show high static dielectric constants, strong absorption in the visible-UV range, and light-dispersive behavior, suggesting suitability for energy storage and photonic applications. Mechanical studies confirm good ductility and resilience under repeated loading, while thermal stability is verified through ab initio molecular dynamics and phonon dispersion analyses. Collectively, these findings highlight Cs 2 XAlH 6 compounds as versatile candidates for hydrogen storage, energy, and optical technologies.

Renewable energy prices are decreasing, making it easier to make energy systems that are good for the environment. High-density storage for renewable energy is possible with hydrogen. This work focuses on the theoretical study of LiXH 3 (where X = Ti, Mn, and Cu), including their structural, electronic, mechanical, thermoelectric, and hydrogen storage properties, using first-principles calculations. LiCuH 3 is more stable than LiMnH 3 and LiTiH 3 , based on the optimization graph. The electronic properties show the metallic nature of these studied hydrides. Born’s criterion indicates that all studied hydrides are brittle for various mechanical applications. LiTiH 3 , LiMnH 3 , and LiCuH 3 are all thought to be able to store hydrogen with gravimetric storage capacities of 5.22%, 4.66%, and 4.11%, respectively. Based on how their thermoelectric properties change with temperature, all the materials under study can absorb heat energy, which shows that they are both electrically and thermally conductive.

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.

To enhance the hydrogen storage performance of Mg-Ni system alloys, multi-elemental alloys incorporating Y element, namely Mg2-xYxNi0.9Co0.1 (x = 0, 0.1, 0.2, 0.3), were synthesized through ball milling and sintering. The microstructures of Mg2-xYxNi0.9Co0.1 (x = 0, 0.1, 0.2, 0.3) alloys were characterized using XRD and SEM/EDS techniques, and the hydrogen storage properties of Mg2Ni0.9Co0.1 and Mg1.7Y0.3Ni0.9Co0.1 alloys were evaluated via the Sieverts method. At a sintering temperature of 500 °C, the Y element existed in the form of Y/Y2O3 phases and displayed no reactivity with other alloy constituents. The addition of Y enhanced the activation performance of Mg-Ni system alloys, because it takes 2 times for Mg1.7Y0.3Ni0.9Co0.1 alloy to complete activation, while Mg2Ni0.9Co0.1 needs 3, albeit causing a slight reduction from 3.6 wt% to 3.2 wt% in the hydrogen storage capacity when Y replaced Mg. The enthalpy of hydrogen desorption of Mg1.7Y0.3Ni0.9Co0.1 alloy was 57.4 kJ mol−1 H2, which was significantly lower than that of Mg2Ni0.9Co0.1 (68.0 kJ mol−1 H2) and Mg2Ni alloy (64.4 kJ mol−1 H2), indicating improved thermodynamic properties. Moreover, the apparent activation energy of Mg2Ni0.9Co0.1 (71.48 kJ mol−1 H2) was lower than that of Mg1.7Y0.3Ni0.9Co0.1 (83.62 kJ mol−1 H2), implying that the addition of Y reduced the kinetic properties.

The Mg1.8Y0.2Ni1−yCoy (y = 0, 0.05, 0.1, 0.15, 0.2) hydrogen storage alloys were prepared following the principles of metallurgy, the phase composition and microstructure of the alloys were studied using XRD and SEM/EDS techniques, and the hydrogen absorption and desorption properties of the alloys were studied using PCT and DSC techniques. The results showed that the addition of Co did not affect the phase composition of Mg1.8Y0.2Ni1−yCoy alloys in the as-cast state and after hydrogen absorption. The Co addition could help refine the microstructure of the alloys to a certain extent. The de-/hydrogenation kinetics of Mg1.8Y0.2Ni1−yCoy (y = 0, 0.1, and 0.2) alloys were improved by adding Co, and the best results were obtained at y = 0.1. The onset decomposition temperature of Mg1.8Y0.2Ni1−yCoy (y = 0, 0.1, and 0.2) alloys were recorded to be 180 °C, 156 °C, and 210 °C, respectively, which were significantly lower than that of Mg2Ni (253 °C). The results revealed that the addition Co could improve the thermodynamic performance of the dehydrogenation process.

The rapid development of micro/nano systems promotes the progress of micro energy storage devices. As one of the most significant representatives of micro energy storage devices, micro hydrogen fuel cells were initially studied by many laboratories and companies. However, hydrogen storage problems have restricted its further commercialization. The γ-graphdiyne (γ-GDY) has broad application prospects in the fields of energy storage and gas adsorption due to its unique structure with rigid nano-network and numerous uniform pores. However, the existence of various defects in γ-GDY caused varying degrees of influence on gas adsorption performance. In this study, Lithium (Li) was added into the intrinsic γ-GDY and vacancy defect γ-GDY (γ-VGDY) to obtain the Li-GDY and Li-VGDY, respectively. The first-principles calculation method was applied and the hydrogen storage performances of them were analysed. The results indicated that the best adsorption point of intrinsic γ-GDY is H2 point, which located at the centre of a large triangular hole of an acetylene chain. With large capacity hydrogen storage, doping Li atom could improve the hydrogen adsorption property of intrinsic γ-GDY; meanwhile, vacancy defect inspires the hydrogen storage performance further of Li-VGDY. The mass hydrogen storage density for Li2H56-GDY and Li2H56-VGDY model were 13.02% and 14.66%, respectively. Moreover, the Li2H56-GDY and Li2H56-VGDY model had same volumetric storage density, with values that could achieve 5.22 × 104 kg/m3.

The nanocrystalline materials for hydrogen storage offer a breakthrough in prospects for practical applications. Their excellent properties are from the combined engineering of many factors: alloy composition, surface properties, microstructure, grain size and others. Nanoengineering can speed up the kinetics, lower the enthalpy of formation and reduce the temperature of releasing hydrogen. The main focus is on the nanostructured metal hydrides, preparing nanograined materials and the effects of nanomaterials on the hydrogen storage properties in this review.

Re2Mg(Ni0.7 − xCo0.2Mn0.1Alx)9 (x = 0‒0.04) alloys are prepared by induction melting, and the influence of the partial substitution of Ni by Al on the structure, hydrogen storage, and electrochemical properties of the alloys are investigated systematically. These alloys mainly consist of two main phases with LaNi5 phase and (La,Mg)2Ni7 phase, and minor LaNi2 phase. The pressure-composition isotherms shows that, with Al content increasing in the alloys, the maximum hydrogen storage capacity decreased from 1.16 wt% (x = 0) to 0.99 wt% (x = 0.04). The changes of enthalpy and entropy reveal that the thermodynamic stability and the disordered degree of the hydride alloys increase with the Al addition. Results of electrochemical studies indicate that the substitution of Al for Ni can noticeably improve the cycle stability of the alloy electrode. The capacity retention after 80 cycles is enhanced from 63.6% (x = 0) to 76.5% (x = 0.04). However, the maximum discharge capacity of the alloys decreases. The Re2Mg(Ni0.7 − xCo0.2Mn0.1Alx)9 (x = 0‒0.04) alloys exhibit excellent dischargeability.

Hydrogen desorption from hydride matrix is still an open field of research. By means of accurate first-principle molecular dynamics (MD) simulations an Mg–MgH2 interface is selected, studied and characterized. Electronic structure calculations are used to determine the equilibrium properties and the behavior of the surfaces in terms of structural deformations and total energy considerations. Furthermore, extensive ab-initio molecular dynamics simulations are performed at several temperatures to characterize the desorption process at the interface. The numerical model successfully reproduces the experimental desorption temperature for the hydride.