Phase structures and electrochemical properties of the Laves phase hydrogen storage alloys Zr1−xTix(Ni0.6Mn0.3V0.1Cr0.05)2

The effects of the partial substitution of Ti for Zr in Zr1−xTix(Ni0.6Mn0.3V0.1Cr0.05)2 alloys are reported in this paper. The main phases C15 and C14 Laves phases, and secondary phase Zr7Ni10 were found. With increasing Ti content, abundance of C15 phase decreases and that of C14 phase increases. Increase of Ti content leads to decrease of the lattice parameters of both C15 and C14 phases. Pressure-composition isotherms show a decrease of the stability of the alloy hydride. Ti substitution for Zr in the alloys is effective to improve the activation and high-rate dischargeability. A critical substitution content of Ti is found at x=0.2. The cycling stability and the high rate dischargeability are deteriorated for the alloy electrodes with high Ti content (x>0.3).