Effects of V content on hydrogen storage properties of V–Ti–Cr alloys with high desorption pressure

Abstract

Hydrogen storage is one of the most important issues to realize hydrogen society especially for on-board usage. Recently, high-pressure metal hydride (MH) tank attracts many attentions due to its high volumetric hydrogen storage density and relatively easy heat management. To emphasize its merits, further improvements of properties of MH, such as capacity, hydrogen desorption capability at low temperature and durability, are required. In this paper, V–Ti–Cr alloys of V-rich compositions were investigated with perspective of increasing of hydrogen desorption pressure and durability. In both of 60at%V–Ti–Cr and 80at%V–Ti–Cr alloys, good relationship between hydrogen desorption pressure and Ti content was observed. In comparing with 60at%V–Ti–Cr alloys, 80at%V–Ti–Cr alloys showed good durability. It is quite notable that relationship between limitation line (upper substitution limit of Ti by Cr without degradation of hydrogen capacity) and desorption pressure for V–Ti–Cr ternary system with V-rich composition is clarified. And also, it is revealed that in the case of V–Ti–Cr ternary system, not only Ti/Cr ratio but also V content is important factor to obtain alloys with high hydrogen desorption pressure. 75at%V–5at%Ti–Cr as-cast sample showed good durability, hydrogen desorption capability at low temperature and relatively high effective hydrogen capacity simultaneously.