Performance and fuel cell applications of reacted ball-milled MgH 2 /5.3 wt% TiH 2 nanocomposite powders.

The present study aimed to enhance the kinetics behavior and destabilize the thermal stability of MgH 2 powder by high-energy milling of Mg powder under 50 bar of H 2 for several hours using Ti-balls as the milling media. The results showed a monotonical increase in Ti content worn off the milling media and introduced into the milled powders. This gradual doping led to homogeneous distribution of fine Ti particles into the Mg/MgH 2 powder matrix without agglomeration or compositional fluctuations at the micro-level. During the activation stage of the powders, achieved at 350 °C/35 bar H 2 prior to hydrogenation kinetics measurements, elemental Ti reacted with H 2 to form fine TiH 2 particles. Our proposed in situ mechanically induced catalyzation approach was found to be mutually beneficial for decreasing the apparent activation energy of decomposition. In addition, introducing 5.3 wt% of TiH 2 to the MgH 2 powder obtained after 50 h led to the achievement of superior enhancement of gas uptake/release kinetics at relatively low temperatures. The nanocomposite MgH 2 /5.3 TiH 2 powder possessed fast hydrogenation/dehydrogenation kinetics behaviors and revealed long cycle lifetimes. This system was successfully employed as a solid-state hydrogen source to charge the battery of a cell-phone device using an integrated Ti-tank/commercial proton exchange membrane-fuel cell system.