Effects of Y Substitution for Ti on the Microstructure and Electrochemical Properties of Ti-V-Fe-Based Hydrogen Storage Alloys

Abstract

In this work, the effects of rare earth metal Y substitution for Ti on the microstructure and electrochemical properties of the hydrogen storage electrode alloys were investigated systematically. It was found by X-ray diffraction and scanning electron microscopy that the main phases of all of the alloys were the C14 Laves phase in a three-dimensional network and the dendritic -based solid solution phase. The grain size of the -based solid solution phase decreased obviously as a small amount of Y was added, but the decrease tendency become very small when the Y content was further increased. The maximum discharge capacity reached a maximum value when was 0.10. Small amount of Y addition favors the cyclic stability and the high rate dischargeability of the alloy, and the maximum values of and reached 76.05% and 73.19%, respectively. But the cyclic stability and the high rate dischargeability decreased with further adding Y. Additionally, electrochemical impendance spectras, linear polarization, anode polarization, and potentiostatic discharge tests were employed to study the electrochemical kinetics of the alloy electrodes.