Hydrogen Storage Properties of Graphite-Modified Mg-Ni-Ce Composites Prepared by Mechanical Milling Followed by Microwave Sintering

The Mg17Ni1.5Ce0.5 hydrogen storage composites with different contents of graphite were prepared by a new method of mechanical milling and subsequent microwave sintering. The small particle size (similar to 25 mu m) and the low echo ratio of power indicate that graphite plays an important role not only as a lubricant during mechanical milling but also as a supplementary heating material during microwave sintering. As a catalyst in the hydriding/dehydriding (H/D) reaction, graphite also improved the hydrogen storage properties of the composites. The hydrogen absorption and desorption capacities of Mg17Ni1.5Ce0.5 with 5 wt pct graphite were 5.34 and 5.30 wt pct H-2 at 573 K (300 degrees C), its onset temperature of dehydriding reaction was 511 K (238 degrees C), and its activation energies of H/D reaction were 40.9 and 54.5 kJ/mol H-2, respectively. The kinetic mechanisms of the H/D reaction are also discussed. DOI: 10.1007/s11661-012-1301-7 (C) The Minerals, Metals & Materials Society and ASM International 2012