Low-cost vanadium-free Ti–Zr–Cr–Mn–Fe based alloys for metal hydride hydrogen compressor under mild conditions

Hydrogen is the ideal green fuel and carbon-neutral energy carrier alternative to nonrenewable fuel sources. The high construction cost of hydrogen refueling stations has become one of the limitations to the further promotion and application of hydrogen energy. To realize 8–22 MPa hydrogen compression under mild conditions, the low cost Ti0.95Zr0.07Cr1.7-xMn0.3Fex (x = 0–0.5) alloys were designed and prepared by magnetic levitation melting in this work. The effect of Fe on Cr substitution on the microstructure and hydrogen storage properties of the alloy has been systematically investigated. With the increase of Fe substitution for Cr, all the alloys maintain a single C14 Laves phase, the thermodynamic plateau curve broadens and rises, while the hydrogen storage capacity diminishes slightly. For a better description of the thermodynamic properties of alloys at high temperatures as the function of temperature, a non-linear Van't Hoff fitting is introduced with satisfactory prediction. On account of significant Fe substitution for Cr, the unit cell shrinks and the interstitial size of alloy decreases, an optimal alloying constituent, Ti0.95Zr0.07Cr1.3Mn0.3Fe0.4, has been proposed and experimentally proved for the first time. This alloy exhibits the best overall performances and the plateau pressure is respectively 5.74 MPa for hydrogenation at 283 K and 25.97 MPa for dehydrogenation at 353 K without apparent hysteresis phenomenon. The hydrogen storage capacity is 1.59 wt% within 3 min and dehydrogenation enthalpy is 21.20 kJ/mol H2. This study provides a comprehensive insight into the low-cost hydrogen storage alloy design and application on quick response and high cycle stability metal hydride hydrogen compressors.