Development of (Ti–Zr)_1.02(Cr–Mn–Fe)₂-Based Alloys toward Excellent Hydrogen Compression Performance in Water-Bath Environments

Abstract

Three series of alloys, Ti 0.92 Zr 0.10 Cr 1.7−x Mn 0.3 Fe x (x = 0.2−0.4), Ti 0.92 Zr 0.10 Cr 1.6−y Mn y Fe 0.4 (y = 0.1−0.7), and Ti 0.92+z Zr 0.10−z Cr 1.3 Mn 0.3 Fe 0.4 (z = 0, 0.015, 0.04), were prepared by induction levitation melting for a metal hydride hydrogen compressor from 8 to 20 MPa at water-bath temperature, with investigation on their crystal structural characteristics and hydrogen storage properties. The results show that a single C14-Laves phase with homogeneous element distribution exists in all of the alloys. The hydrogen ab-/ desorption plateau of the alloys is increased as the Fe, Mn, or Ti content increases due to decrement of the interstitial site radius originated from the respective atomic size. The hydrogen storage capacity of the alloys also correlates negatively with the hydrogen affinity of interstitial sites due to the influence of the element electronegativity. In a comprehensive consideration of the hydrogen storage performance for application, the Ti 0.935 Zr 0.085 Cr 1.3 Mn 0.3 Fe 0.4 alloy shows saturated hydrogenation under 8 MPa at 293 K and dehydrogenation around 24.91 MPa pressure at 363 K with a hydrogen capacity of 1.74 wt %, as well as excellent cycling performance and mere hysteresis. The Ti 0.92 Zr 0.10 Cr 1.0 Mn 0.6 Fe 0.4 alloy is another promising candidate with a remarkable hydrogen capacity of 1.86 wt % at 283 K and a dehydrogenation pressure of 27.94 MPa at 363 K, together with a satisfactory cycling durability. This study can guide the compositional design of AB 2 -type hydrogen storage alloys for hydrogen compression application.

Experimental and Theoretical Investigation on the Enhanced Hydrogen Storage Performance of Ti–Cr–Mn–Fe-Based Alloys Modified by Nb Substitution

“…The van’t Hoff equation can be described as follows ln ( P P 0 ) = normalΔ H 0 R T − normalΔ S 0 R where P is the equilibrium hydrogen plateau pressure of metal hydrides, T is temperature, Δ H 0 and Δ S 0 are the standard enthalpy and entropy changes of metal hydride formation, respectively, P 0 is the standard atmospheric pressure and equal to 101,325 Pa, and R is the gas constant (8.314 J/mol H 2 K). However, the van’t Hoff equation only applies to calculations close to the ideal condition, while in this work, the hydrogen atmosphere will significantly deviate from the ideal gas due to the high hydrogen plateau pressure of the alloys . Therefore, proper corrections to the van’t Hoff equation should be performed with fugacity f replacing the pressure term in eq ln nobreak0em0.25em⁡ f = normalΔ H 0 R T − normalΔ S 0 R …”

“…However, the van't Hoff equation only applies to calculations close to the ideal condition, while in this work, the hydrogen atmosphere will significantly deviate from the ideal gas due to the high hydrogen plateau pressure of the alloys. 29 Therefore, proper corrections to the van't Hoff equation should be performed with fugacity f replacing the pressure term in eq 1…”

“…26 For instance, in the investigations performed by Zhou et al, 27 the decreased plateau hysteresis of Ti−Mn-based alloys exhibits a clear correlation to descending plateau pressure as well as ascending unit cell volume, consistent with the machine learning results. 28 Also in experimental research performed by Cao et al, 29,30 Ti−Zr−(V)−Cr−Mn−Fe-based alloys exhibit increased plateau pressure, deteriorating hysteresis, and decreased interstitial size simultaneously as the mount of Mn or Fe substitution for Cr is increased. Therefore, according to relevant reports, the hysteresis-pressure characteristic of AB 2type alloys is a universal obstacle to MHHC development with higher pressure requirements.…”

Microstructure and Hydrogen Storage Behavior of TiCrMo Alloys Fabricated via Melt Spinning

“…However, the storage and transportation of hydrogen remain formidable challenges that impede its widespread adoption. 2,3 To address this, solid-state hydrogen storage is considered the safest and most effective method, particularly for hydrogen transportation. 4,5 Consequently, the development of high costefficient hydrogen storage materials has received considerable attention.…”

“…It offers efficient raw materials, reducing agents, and high-quality heat sources for industries such as refining, steel, and metallurgy, leading to significant reductions in carbon emissions. However, the storage and transportation of hydrogen remain formidable challenges that impede its widespread adoption. , To address this, solid-state hydrogen storage is considered the safest and most effective method, particularly for hydrogen transportation. , Consequently, the development of high cost-efficient hydrogen storage materials has received considerable attention. Among these, V-based body-centered cubic (BCC)-type alloys have been extensively investigated due to their higher mass hydrogen storage density than AB-type, AB 2 -type, AB 3.5 -type, and AB 5 -type alloys under water-bath environments. − The BCC structure of V-based alloys offers a greater number of tetrahedral and octahedral hydrogen storage sites with theoretical hydrogen storage capacity of 3.80 wt %, and the incorporation of additional elements, such as Ti, Zr, and Cr, can further enhance their hydrogen storage performance.…”