Hydrogen sorption and electrochemical properties of alloys: Systems Zr-Ti-Ni-V-Mn with laves phase structures

Abstract

Using scanning electron microscopy and x-ray phase analysis techniques, it is shown that the C14-type Laves phase with a wide homogeneity reaching the AB2.3 stoichiometry is the main phase in the Zr0.5Ti0.5NiyV0.5Mnx alloys, where y = 0.8–1.4 and x = 0.1–1.7. With the increase in the nickel and manganese contents and in the stoichiometric ratio B/A, the hydrogen capacity decreases from 2 to 1.6 wt %, the equilibrium pressure of hydride phases increases, and the hydrides become less stable. The highest discharge capacity is reached for stoichiometric ratios AB1.7–2.3, where the maximum discharge capacity at a discharge current density of 100 mA/g is 300 (mA h)/g. Alloys that contain ferrovanadium in place of vanadium are also considered.