Performance and Fuel Cell Applications of Reacted Ball-milled MgH/5.3 wt% TiH Nanocomposite Powders

The present study aimed to enhance the kinetics behavior and destabilize the thermal stability of MgH powder by high-energy milling of Mg powder under 50 bar of H 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 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 prior to hydrogenation kinetics measurements, elemental Ti reacted with H to form fine TiH particles. Our proposed 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 to the MgH powder obtained after 50 h led to the achievement of superior enhancement of gas uptake/release kinetics at relatively low temperatures. The nanocomposite MgH/5.3 TiH 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.