A panoramic overview of hydrogen storage alloys from a gas reaction point of view

This is a broad historical and property-related review of the extraordinary variety of hydriding alloys that have been developed. The principal focus is on reactions of alloys with gaseous H-2 and their important H-capacity and PCT (pressure-composition-temperature) properties. However, there are a number of important secondary properties that must also be considered: activation, decrepitation, H-2 absorption/desorption kinetics, impurity effects, cyclic stability, safety, raw materials cost and ease of manufacture, among others. The main part of this survey will cover the families of alloys that will reversibly store H-2 at temperatures of 0-100 degrees C and pressures of 1-10 atm absolute, ranges useful to many applications. Alloys include solid solutions and intermetallic compounds of the generic families AB(5), AB(2), AB, A(2)B, among others. Conventional alloys are reaching thermodynamic limits in PCT and H-capacity. Near-term R&D is likely to focus new directions toward the areas of catalyzed complex hydrides and carbon. (C) 1999 Elsevier Science S.A. All rights reserved.