Improved electrochemical performance of BCC alloy by Ni addition and surface modification with AB5 alloy

The hydrogen storage and electrochemical properties of the Ti0.32Mn0.22Cr0.1V0.28Nix (x = 0, 0.05, 0.15, 0.2) alloys were investigated. XRD results revealed that the addition of Ni resulted in the formation of C14 Laves phase. With the increasing Ni content, the lattice parametera of BCC phase and the lattice parametera and c of C14 Laves phase decreased. The Ni addition reduced the hydrogen absorption/desorption capacities at gas solid reaction, but improved the electrochemical discharge capacity significantly. The maximum discharge capacity of 392 mAh g(-1) was obtained for the Ti0.32Mn0.22Cr0.1V0.28Ni0.15 alloy. Cycling measurement revealed that the discharge capacity of the Ti0.32Mn0.22Cr0.1V0.28Ni0.15 alloy degraded with the increasing cycle number, decreasing to 63% of the maximum discharge capacity after 100 cycles. Further improvement on the activation and cycle life of this alloy can be achieved by surface modification with 20 wt.% LaNi3.55Co0.75Mn0.4Al0.3 addition. (c) 2008 Elsevier B.V. All rights reserved.