Influence of boron introduction on structure and electrochemical hydrogen storage properties of Ti-V-based alloys

In order to improve the properties of TieV-based alloys in the electrochemical system, Ti0.17Zr0.08V0.35Cr0.1Ni0.3Bx (x = 0-0.04) alloys were prepared and their structural and electrochemical performances had been systematically investigated in this study. XRD patterns show that they are mainly comprised of a C14 Laves phase and a body centered cubic (BCC) solid solution phase. The introduction of boron has little effect on the structure, while it remarkably influences the electrochemical performances. The cycle life of each electrode made from the studied alloy is obviously improved. For instance, the cycle retention after 200 charge-discharge cycles is more than 90%. Furthermore, high rate dischargeability (HRD) is also enhanced after boron introduction. It is also found that the charge-transfer reaction resistance R-ct, the limiting current density I-L, and the hydrogen diffusion coefficient D are first decreased and then increased with the increase of boron amount. Taking into consideration various factors, the introduction of boron in the alloy has an optimal value of x = 0.01. (C) 2015 Elsevier B.V. All rights reserved.