Effect of Ni addition on dehydrogenation behavior of MgH2

Magnesium hydride (MgH2) is an attractive and widely researched hydrogen storage material because of its high hydrogen capacity and lower cost of production coupled with the availability of Mg. However, higher desorption temperature and sluggish kinetics are the limitations of widespread use of MgH2 as hydrogen storage material. The present study deals with the effect of the addition of Ni on the dehydrogenation behavior of as-synthesized MgH2 from coarse commercial-grade magnesium powder (purity 99.8%). Optimization of the process parameters for the conversion of Mg powder to MgH2 in bulk quantity and characterization of MgH2 were carried out. Mg2NiH4 phase could be formed by ball milling in planetary ball mill of as-synthesized MgH2 and Ni powder. Thermal analyses such as TG–DTA, DSC, and pressure–composition isotherms were used to understand the dehydrogenation behavior of MgH2 and MgH2–Ni. The release of hydrogen was found to start from 220 °C for MgH2–Ni by the combined action of the addition of Ni in MgH2 and particle size reduction because of ball milling.