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

Abstract

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.