Cyclic hydrogen storage properties of Mg milled with nickel nano-powders and NiO

The cyclic hydrogen storage properties of nanocrystalline composite of Mg-3Ni-2NiO (wt.%) produced by mechanical milling with nickel nano-powders under the hydrogen pressure have been investigated. The results show that the composite has excellent hydrogen storage properties. Its maximum hydrogen capacity is about 6.4wt.%. The hydrogen absorption time is about 54s in which 6.1 wt.% of hydrogen has been absorbed at 200 degrees C. The hydrogen desorption time is about 310s in which 6.2 wt.% of hydrogen has been discharged in the temperature range from 290 degrees C to 320 degrees C under the hydrogen pressure of 0.1 MPa. The composite also has a better cyclic hydrogen storage behavior. The hydrogen capacity is decreased less than 0.1 wt.% after 60 times of cycling. However, the hydrogen absorption time and desorption time are increased in proportion with the cyclic numbers. The reason for these may be that the MgO, formed during the cycling process, impedes an intimate contact of the catalyst with the MgH2. (C) 2008 Elsevier B.V. All rights reserved.