Enhanced hydrogen sorption kinetics of Mg50Ni–LiBH4 composite by CeCl3 addition

Mg50Ni–LiBH4 and Mg50Ni–LiBH4–CeCl3 composites have been prepared by short times of ball milling under argon atmosphere. Combination of HP–DSC and volumetric techniques show that Mg50Ni–LiBH4–CeCl3 composite not only uptakes hydrogen faster than Mg50Ni–LiBH4, but also releases hydrogen at a lower temperature (225 °C). The presence of CeCl3 has a catalytic role, but it does not modify the thermodynamic properties of the composite which corresponds to MgH2. Experimental studies on the hydriding/dehydriding mechanisms demonstrate that LiBH4 and Ni lead to the formation of MgNi3B2 in both composites. In addition, XRD/DSC analysis and thermodynamic calculations demonstrate that the addition of CeCl3 accounts for the enhancement of the hydrogen absorption/desorption kinetics through the interaction with LiBH4. The in situ formation and subsequent decomposition of Ce(BH4)3 provides a uniform distribution of nanosize CeB4 compound, which plays an important role in improving the kinetic properties of MgH2.