A possible route to making magnesium fit for hydrogen storage in automotive applications

The high hydrogen storage capacity of magnesium, coupled with the reversibility of hydrogen absorption/desorption, give it an advantage over other metallic systems. However, a high hydrogen release teimperature is an obstacle to its mobile hydrogen storage applications. Attempts to reduce this temperature below the desired level of 200°C have been unsuccessful. While nanostructuring does improve the storage kinetics, the temperature dependence of hydrogen pressure cannot be controlled in this way. We proposed a novel approach to Mg processing using equal channel angular pressing, which changes both the kinetics and the thermodynamics of hydrogen storage. ECAP produces a long-lived non-equilibrium microstructure characterized by ultrafine grains, enhanced vacancy concentration and excess volume. These factors induce thermodynamic shifts in a desired way. Future efforts will be directed at ECAP optimization in order to reach the temperature and pressure levels required for use of magnesium as a hydrogen storage material for automotive applications.