Enhanced Cycle-Life Performance in Ti-V-Cr-Nb-Mo High-Entropy Alloys for Reversible Hydrogen Storage at Room Temperature

This study focuses on the (TiV)50Cr50-x(NbMo)x (x = 15, 20, and 25) series of high-entropy alloys, which were predicted by machine learning to have high capacity and favorable thermodynamic properties. They are synthesized by arc melting and form single-phase bcc solid solutions. All three compositions rapidly absorb H2 at room temperature and show strong tunability of the hydride phase formation thermodynamics, as well as of their total and reversible capacities. The most promising composition demonstrates a favorable enthalpy of hydride formation (–35.5 kJ/mol·H2) and achieves a reversible capacity above 2.0 wt % upon 20 cycles of absorption-desorption at room temperature. These results are among the highest reported for this class of alloys.