Influence of various additives in vanadium-based alloys V 3TiNi 0.56 on secondary phase formation, hydrogen storage properties and electrode properties

Abstract

Microstructures, hydrogen storage properties and electrode properties of vanadium-based alloys of V 3TiNi 0.56M 1 (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 V 3TiNi 0.56 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 3TiNi 0.56M 0.24 (M = Hf, Nb, Ta and Pd) showed a higher discharge capacity than 330 A h kg 1.