Effects of alloying elements (Al, Mn, Ru) on desorption plateau pressures of vanadium hydrides: An experimental and first-principles study

Abstract

Vanadium-based alloys are promising for the reversible, compressed storage of renewable hydrogen. To improve the hydrogen desorption plateau pressure of vanadium hydrides, V-3A binary alloys (i.e. V 97 Al 3 , V 97 Mn 3 , and V 97 Ru 3) were prepared by vacuum arc melting. Hydrogen absorption and desorption properties of the newly prepared V-3A samples were studied, and compared to vanadium hydrides, by pressure-composition-temperature measurements and first-principles calculations. Among V-3A binary alloys, V 97 Ru 3 achieved the highest hydrogen desorption plateau pressure while accommodating the highest atomic percentage of hydrogen. Meanwhile, it was also the alloy with the highest measured hardness. 2 Hydrogen desorption plateau pressures of V-3A alloys were complemented with DFT calculated formation energies. Calculated DOS, ELF and Bader charges showed that the influence of alloying on the electronic properties of the hydrides was comparable for Mn and Ru; whereas for Al alloying, vanadium dihydride bonding interactions were modified the most.

Hydrogen storage properties of Li-decorated B2S monolayers: A DFT study

“…In the former, during the absorption and desorption processes, chemical bonds need to be broken and formed, affecting the (de)hydrogenation kinetics. [5][6][7] For the latter, highly porous open structures decorated with lightweight metal atoms, with an effort to improve their interactions with hydrogen molecules [8][9][10], attracted significant interest in recent years. [11][12][13][14] Among these are the metal decorated, atomically thin two-dimensional (2D) materials.…”

Mechanochemical Synthesis and Hydrogen Sorption Properties of a V-Ni Alloy

“…Most information on pure V is available for the transformation toward the dihydride, VH 2 : Ono reported a ∆H of 49.4 kJ/mol [28], while Reilly reported a ∆H of 40 ± 1 kJ/mol [29]. Liu et al measured the ∆H and ∆S of about 39.6 kJ/mol and 120 J/(mol K) for pure V and revealedthat these values tended to decrease with a partial replacement of V by 3 at% of Al, Mn e Ru [6]. Griffiths et al reported the enthalpy variation for the hydrogenation of pure vanadium for a low hydrogen content (H/M < 0.03) in the α (solid solution) phase.…”

“…When measuring the pressure composition isotherms, one can observe various pressure plateaus; however, the one corresponding to the transition from the solid solution (α phase) to VH 0.5 has an extremely low pressure, on the order of 1 mbar [3,4]; therefore, it is extremely difficult to remove hydrogen at low hydrogen concentrations. One way to partially mitigate the irreversible storage of hydrogen in vanadium is the partial substitution of V with other metals, such as Ti, Cr, Ni, Fe, etc., which generally leads to a higher equilibrium pressure and a sloping plateau [3,[5][6][7] in the pressure composition isotherms.…”

The Thermodynamic Way of Assessing Reversible Metal Hydride Volume Expansion: Getting a Grip on Metal Hydride Formation Overpotential

“…Reversible metal hydrides show upon hydrogenation a substantial volume change, e.g. up to about + 40% for V ⟶ VH 2 , 1 which is an important safety aspect to consider in the design of metal hydride tanks. However, the powdery, transient nature of metal hydride beds makes the measurement of such expansion forces not trivial; 2 compaction into pellets is not a remedy since the additional compression energy put into the material makes its presence forcibly felt once the system runs through sorption cycles hence it may even aggravate the issue.…”