Phase structures and electrochemical properties of Cr-added V3TiNi0.56Hf0.24Mn0.15 alloys

The phase structures and the electrochemical properties of the V3TiNi0.56Hf0.24Mn0.15Crx (x=0, 0.1, 0.2 and 0.3) alloys have been studied. It is found that the alloys consist of a main phase with b.c.c structure and a Laves-type secondary phase with hexagonal structure. Increase on Cr content leads to change in the chemical composition and lattice parameters of each phase as well as in the molar fraction ratio of the main phase to the secondary phase. In V3TiNi0.56Hf0.24Mn0.15Crx alloys, increasing Cr content can improve the durability of the alloy electrode in KOH electrolyte despite the fact that its maximum hydrogen desorption capacity decreases slightly and high rate capability worsens.