Hydrogen storage properties of Ti_(1.4)V_(0.6)Ni + x Mg (x = 1-3, wt.%) alloys

摘要

We prepared Ti_(1.4)V_(0.6)Ni ribbons by arc-melting and subsequent melt-spinning techniques. Ti_(1.4)V_(0.6)Ni + x Mg (x = 1, 1.5, 2, 2.5 and 3, wt.%) composite alloys were obtained by the mechanical ball-milling method. The structures and hydrogen storage properties of alloys were investigated. Ti_(1.4)V_(0.6)Ni + x Mg composite alloys contained icosahedral quasicrys-talline phase, Ti_2Ni-type phase, β-Ti solid-solution phase and metallic Mg. The electrochemical and gaseous hydrogen storage properties of alloys were improved with Mg addition. Ti_(1.4)V_(0.6)Ni + 2 Mg alloy showed maximum electrochemical discharge capacity of 282.5 mAh g~(-1) as well as copacetic high-rate discharge ability of 82.3% at the discharge current density of 240 mA g~(-1) compared with that of 30 mA g~(-1), and the cycling life achieved above 200 mAh g~(-1) after 50 consecutive cycles of charging and discharging. The hydrogen absorption/desorption properties of Ti_(1.4)V_(0.6)Ni + x Mg (x = 1, 2 and 3, wt.%) alloys were better than Ti_(1.4)V_(0.6)Ni. Ti_(1.4)V_(0.6)Ni + 3 Mg alloy also exhibited a favorable hydrogen absorption capacity of 1.53 wt.%. The improvement in the hydrogen storage characteristics caused by adding Mg may be ascribed to better hydrogen diffusion and anti-corrosion ability.