Recent developments in aluminum-based hydrides for hydrogen storage

Aluminum hydride (AlH3), and the complex aluminum hydrides (e.g., M3AlH6, MAlH5, M2AlH7, M(AlH4)(n)), make up a fascinating class of materials that have received considerable attention over the past 60 years for their use as explosives, reducing agents, solid rocket propellants, as well as a hydrogen source for portable power systems. The recent renaissance in hydrogen storage research, particularly for automotive applications, has generated renewed interest in aluminum-based hydrides due to their capacity to store up to 11 wt% hydrogen with volumetric capacities up to 150 g H-2/L (more than twice that of liquid hydrogen). In addition, hydrogen can be released from these materials by low temperature thermolysis (<100 degrees C), making them well-suited for proton exchange membrane fuel cells and other low temperature applications. This article covers recent research on aluminum-based hydrides, including crystal structures, thermodynamics, kinetics, hydrogenation conditions, and regeneration methods.