Effect of rapid solidification on the structural and electrochemical properties of the Ti-V-based hydrogen storage electrode alloy

The structural and electrochemical properties of the as-cast and rapidly solidified Ti0.8Zr0.2V2.4Mn0.48Cr0.72Ni0.9 alloys were studied. Both the as-cast and the rapidly solidified alloys were mainly composed of a C14 Laves phase matrix with hexagonal structure and a V-based solid solution phase with body centered cubic (BCC) structure. The V-based solid solution phase showed very fine dendrites in the rapidly solidified alloy instead of the large dendrites as observed in the as-cast alloy. In addition, the content of the C14 Laves phase in the alloy decreased greatly after rapid solidification. Electrochemical measurements indicated that the rapidly solidified alloy had a lower discharge capacity, a slower activation rate, a worse high rate dischargeability, a smaller exchange current density and limiting current density, but an improved cycle life compared with that of the as-cast alloy. (C) 2007 Elsevier B.V. All rights reserved.