Structure and Electrochemical Characteristics of Ti―V―based Solid Solution/AB5―type La―Mg―based Alloy Composite Hydrogen Storage Material

Composite hydrogen storage alloy Ti0.10Zr0.15V0.35Cr0.10Ni0.30 + 5wt% La0.85Mg0.25Ni4.5Co0.35Al0.15 was prepared by two―step arc melting. X―ray diffractometry (XRD) and scanning electron microscope―energy dispersive spectroscopy (SEM―EDS) show that the main phase of the composite alloy consists of V―based solid solution phase with BCC structure and C14 Laves phase with hexagonal structure, while secondary phase also exists in the composite alloy. Electrochemical studies show that distinct synergetic effect appears during the composite process. The real maximum discharge capacity of the composite alloy electrode is 361.8 mAh/g at 303 K, and the low temperature dischargeability (LTD) of the composite alloy electrode is 4.05 times as high as that of the matrix alloy electrode at 233 K. The high rate dischargeability (HRD), the charge–transfer resistance (Rct) and the exchange current density (I0) of the composite alloy electrode are 26.87 % bigger, 37.25 mΩ lower and 115.45 mA/g higher than that of the matrix alloy electrode, respectively. The hydrogen diffusion coefficient (D) in the bulk of the composite alloy is 6.13×10―10 cm2/s bigger than that of the matrix alloy.