Influence of various additives in vanadium-based alloys V3TiNi0.56 on secondary phase formation, hydrogen storage properties and electrode properties

Microstructures, hydrogen storage properties and electrode properties of vanadium-based alloys of V(3)TiNi(0.56)M(x) (M = Al, Si, Mn, Fe, Co, Cu, Ge, Zr, Nb, Mo, Pd, Hf and Ta; x = 0.046 and 0.24) were investigated in order to clarify the influences of additives, All additives, except for zirconium and hafnium, did not change the phase structure composed of a vanadium-based solid solution main phase and a TiNi-based secondary phase. A little addition of an element M with x = 0.046 to V3TiNi0.56 did not significantly change the storage capacity, preserving a higher discharge capacity than 290 A h kg(-1). Further addition of Group IVB-VIIB elements (Zr, Hf, Nb, Ta, Mo and Mn) scarcely changed the hydrogen storage properties with x = 0.24, while the addition of Group VIII-IVA elements (Fe, Co, Cu, Al, Ge and Si), except for Pd, brought about a decrease in the hydrogen storage capacity obtained between 3.3 and 0.01 MPa. The alloys V(3)TiNi(0.56)M(0.24) (M = Hf, Nb, Ta and Pd) showed a higher discharge capacity than 330 A h kg(-1).