Effect of different additives on the hydrogen storage properties of the MgH2-LiAlH4 destabilized system

The hydrogen storage properties of the MgH2-LiAlH4 (4 : 1) composite system with and without additives were studied. 5 wt.% of TiF3, NbF5, NiF2, CrF2, YF3, TiCl3·1/3AlCl3, HfCl4, LaCl3, CeCl3, and NdCl3, respectively, was added to the MgH2-LiAlH4 (4 : 1) mixture, and their catalytic effect was investigated. Temperature programmed desorption results show that addition of metal halides to the MgH2-LiAlH4 (4 : 1) composite system improves the onset desorption temperature. The hydrogen desorption properties of metal halide-doped MgH2-LiAlH4 (4 : 1) composites were also improved as compared to the undoped MgH2-LiAlH4 (4 : 1) composite. Furthermore, the activation energy and the change in enthalpy in the doped and undoped composite were measured by differential scanning calorimetry. In addition, the reaction pathway of the MgH2-LiAlH4 (4 : 1) composite system and the mechanisms that work in this composite during the de/re-hydrogenation process were determined by X-ray diffraction.