Development of (Ti–Zr)1.02(Cr–Mn–Fe)2-Based Alloys toward Excellent Hydrogen Compression Performance in Water-Bath Environments

Three series of alloys, Ti0.92Zr0.10Cr1.7–xMn0.3Fex (x = 0.2–0.4), Ti0.92Zr0.10Cr1.6–yMnyFe0.4 (y = 0.1–0.7), and Ti0.92+zZr0.10–zCr1.3Mn0.3Fe0.4 (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 Ti0.935Zr0.085Cr1.3Mn0.3Fe0.4 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 Ti0.92Zr0.10Cr1.0Mn0.6Fe0.4 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 AB2-type hydrogen storage alloys for hydrogen compression application.