Theoretical Investigation of Mg-based alloys for hydrogen storage
Résumé
Hydrogen is a promising energy carrier, compatible with the sustainable energy concept. In this field, solid-state hydrogen-storage is a key challenge in developing hydrogen economy. The capability of absorption of large quantities of hydrogen makes intermetallic systems of particular interest. Light metals, especially magnesium, possess a high gravimetric hydrogen density but not the capabilities of good kinetic and absorption/desorption process. Improvement of these can be achieved by magnesium based alloys and in this context, theoretical prediction of new structures would be useful to orient prospective experimental synthesis. In this work, efforts have been devoted to the theoretical investigation of binary systems with pressure consideration. An efficient prediction of stable alloys under pressure for magnesium-based system was performed at ab initio level. The effect of pressure change radically the minimal energy compositions and various rich-Mg compounds were found. Results are in agreement with recent exploration and new synthesis methods. For interesting alloys, a careful investigation of potential hydrides has been performed, and electronic properties denote interesting informations on hydrogen atom behaviour in magnesium-based alloys. Results are giving attractive insights on identifying destabilized metal hydrides and encouraging the use of similar work to design hydride systems.