Low-temperature hydrogen storage in AB2 type alloys tuned by trace V3Al substitution for Cr at 233 K

AB 2 type alloys are widely regarded as promising solid-state hydrogen storage materials due to their rapid kinetics and low cost, yet their limited reversible capacity severely restricts deployment in low-temperature and high-altitude scenarios. In this study, we propose a trace V 3 Al substitution strategy to enable efficient low-temperature hydrogen absorption in AB 2 type alloys. A Ti 0.98 Zr 0.05 Cr 1.25 Mn 0.5 Fe 0.25 hydrogen storage alloy capable of operating at 233 K was prepared. Introducing a small amount of V 3 Al to partially replace Cr in Ti 0.98 Zr 0.05 Cr 1.15 Mn 0.5 Fe 0.25 (V 0.75 Al 0.25 ) 0.1 markedly improved compositional uniformity and increased the unit-cell volume, which enhanced alloy-hydrogen binding and eliminated the need for high-temperature activation. As a result, the alloy achieved a high hydrogen storage capacity of 1.84 wt% at 233 K, accompanied by improved structural robustness. In addition, cycling-induced lattice distortion was significantly suppressed, leading to zero detectable capacity decay over 50 cycles. These findings establish an effective compositional design route for high-performance AB 2 -type hydrogen storage alloys and accelerate their application in harsh environments.