Laves phase double substitution alloy design and device filling modification for Ti-based metal hydride hydrogen compressors

Abstract

The ambition of carbon neutrality has become a common pursuit for researchers worldwide, and hydrogen as a green and clean energy carrier is expected to contribute to this achievement. Since hydrogen fuel cell vehicles require a high input hydrogen pressure, compressors in hydrogen refueling stations are thus indispensable for the large-scale application of hydrogen energy. Compared to conventional mechanical hydrogen compressors, metal hydride based hydrogen compressors have the advantages of high security and low cost, providing a viable solution for hydrogen refueling station development. Herein, two series of Ti0.95Zr0.07Cr1.3-xMnxFe0.4 (x = 0.2, 0.3, 0.4, 0.6) and Ti0.95Zr0.07Cr1.0Mn0.6Fe0.4-yCuy (y = 0.1, 0.15, 0.2, 0.3) alloys were designed to achieve 8–22 MPa hydrogen compression in water bath at 283–353 K. All the as-prepared alloys exhibit the single hexagonal C14 Laves phase structure. In particular, the double substitution of Cr and Fe by Cu and Mn elements in Ti–Zr–Cr–Mn–Fe alloy can enlarge its hydrogen storage capacity without varying the equilibrium pressure. For instance, Ti0.95Zr0.07Cr1.0Mn0.6Fe0.25Cu0.15 alloy has a hydrogenation plateau pressure of 6.16 MPa at 283 K and a dehydrogenation plateau pressure of 24.23 MPa at 353 K, with the max hydrogen capacity of 1.72 wt%. Furthermore, the relative high density molding method of metal hydride bed with 20 g of alloy powder was developed. The binder epoxy resin and the thermal conductor flake graphite were selected and added into the alloys to form metal hydride compacts (MHCs). The structural stability of modified MHCs can be enhanced due to the formation of a three-dimensional grid structure, with a higher resistance to pulverization and degradation. The improved thermal conductivity involving a filling compact strategy can significantly shorten hydrogenation reaction time by 50% and lower the abrupt temperature of metal hydride bed by 20 K with excellent stability over 100 cycles, and provide new insights of the development of safe and efficient hydride hydrogen compressor.