Study of hydrogen storage properties of oxygen modified Ti- based AB2 type metal hydride alloy

Abstract

A multi component AB2 type hydrogen storage intermetallic alloy (A = Ti0.85Zr0.15, B2 = Mn1.22Ni0.22Cr0.2V0.3Fe0.06; was investigated in this work. The intermetallic specified above was modified by oxygen to yield the composition AB2O0.05. The oxygen was introduced by adding TiO2 to the charge, with corresponding decrease of the Ti amount, followed by arc melting and annealing at the same conditions as for the oxygen free AB2-type alloy. The addition of oxygen to the alloy did not change much the PCT properties; the only difference was that the plateau pressure for the oxygen-modified alloy increased slightly. Both alloys have shown to be excellent candidates for H2 storage, particularly for utility vehicles, due to their relatively high reversible H2 storage capacity (1.6 wt%) and low plateau pressure at room temperature (<5 bar). The addition of oxygen improved hydrogen absorption kinetics in the AB2 alloy allowing it to immediately absorb H2 without activation while for the non-modified sample an incubation period (30 min) was observed at the same conditions.