Improvement of hydrogen storage properties of the AB2 Laves phase alloys for automotive application

Hydrogen storage properties of the Ti1.1CrMn AB(2)-type Laves phase alloys, for both low (-30 degrees C) and high (80 degrees C) temperature applications, are improved by substituting Zr at 11 site. In agreement with the larger radius of Zr than Ti, the lattice volume of (Ti1-xZrx)(1.1)CrMn (x = 0, 0.05, 0.06 and 0.1) alloys, prepared by arc melting, increases with x. The increase in the Zr content leads to a decrease in the equilibrium hydrogen sorption pressure plateau and faster absorption kinetics, associated with an increase in the hydrogen storage capacity from 1.9 to 2.2wt% for Ti1.1CrMn and (Ti0.9Zr0.1)(1.1)CrMn alloys, respectively. At -5 degrees C, (Ti0.9Zr0.1)(1.1)CrMn alloy reversibly absorbs and desorbs 2.2wt% at 160bar within 250s. Based on thermodynamic calculated values, the optimized Zr substituted alloy (Ti0.9Zr0.1)(1.1)CrMn desorbs hydrogen at 3.2bar at -30 degrees C and 135bar at 80 degrees C. This is a significant reduction of the sorption pressure plateau as compared with the current technology for mobile applications based on Ti1.1CrMn alloy with hydrogen desorption plateau above 400bar at 80 degrees C. Finally, the mechanism of improved hydrogen storage properties is discussed based on the radius and the hydrogen affinity of the substituting element. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.