Effect of non-stoichiometric Mn and Cr on the hydrogen storage properties of Ti–Mn-based alloys

Abstract

The effects of non-stoichiometric Mn and Cr on the hydrogen storage properties of Ti–Mn-based Ti_0.84Zr_0.16Mn_0.9+xCr_0.7Fe_0.1 (x = 0, 0.1, 0.2) and Ti_0.84Zr_0.16Mn_0.9Cr_0.7+yFe_0.1 (y = 0, 0.1, 0.2, 0.3) alloys were investigated. The alloys were synthesized by arc melting and crystallized in a single C14-type Laves phase structure. With increasing Mn and Cr content, the equilibrium plateau pressures of the alloys during hydrogen absorption/desorption increased markedly, while the plateaus became flatter and the maximum hydrogen absorption capacities showed a slight decrease. Lower Mn/Cr ratios contribute to reduced hysteresis and lower plateau pressures. However, this improvement is associated with a decline in hydrogen storage capacity. The cyclic performance of the Ti_0.84Zr_0.16Mn_0.9Cr_0.7Fe_0.1 alloy, which exhibited excellent hydrogen storage properties, was studied. It was found that the capacity retention rate reached 96.2% after 500 hydrogenation–dehydrogenation cycles.