Enhanced dehydrogenation properties of LiAlH4–Mg2NiH4 nanocomposites via doping Ti-based catalysts

Abstract

Metal alanate and magnesium-based hydride complex has potential to promote the application of hydrogen storage materials in energy storage systems. In this work, the hydrogen storage properties of LiAlH4–Mg2NiH4 destabilized system with Ti-based additives were investigated. Both the dehydrogenation temperature and kinetics of LiAlH4–Mg2NiH4 were significantly improved by doping TiF3, surpassing those of the Ti- and TiO2-doped LiAlH4–Mg2NiH4 composites. Particularly, the onset dehydrogenation temperature of the TiF3 doped LiAlH4–Mg2NiH4 composite was reduced to as low as 50 °C, far superior to that of the undoped sample and the Ti- and TiO2-doped samples. The hydrogen desorption activation energy of TiF3-doped LiAlH4–Mg2NiH4 composite was 81.56 kJ mol−1 fitted by Johnson–Mehl–Avrami model, which was lower than that of the undoped composite (85.30 kJ mol−1). The XPS results indicated that Al3Ti (Ti0) phase could be in situ formed during dehydrogenation process, exerting positive catalytic effect on the dehydrogenation of the TiF3-doped LiAlH4–Mg2NiH4 composite. Moreover, the TiF3-doped LiAlH4–Mg2NiH4 composite also exhibited desirable re-hydrogenation behavior.