Enhanced Hydrogen Storage Kinetics and Stability by Synergistic Effects of in Situ Formed CeH2.73 and Ni in CeH2.73-MgH2-Ni Nanocomposites

Abstract

Mg-based materials are promising candidates for high capacity hydrogen storage. However, their poor hydrogenation/dehydrogenation kinetics and high desorption temperature are the main obstacles to their applications. This paper reports a method for in situ formation of cycle stable CeH2.73-MgH2-Ni nanocomposites, from the hydrogenation of as-melt Mg80Ce18Ni2 alloy, with excellent hydrogen storage performance. The nanocomposites demonstrate reversible hydrogen storage capacity of more than 4.0 wt %, at a low desorption temperature with fast kinetics and long cycle life. The temperature for the full hydrogenation/dehydrogenation cycle of the composites is significantly decreased to 505 K, which is about 100 K lower than that for pure Mg. The hydrogen desorption activation energy is 63 ± 3 kJ/mol H2 for the composites, which is significantly lower than those of Mg3Ce alloy and pure Mg (104 ± 7 and 158 ± 2 kJ/mol H2, respectively). X-ray diffraction and transmission electron microscopy have been used to revea...