Hydrogen storage properties of La_(1.8)Ca_(0.2)Mg_(14)Ni_3 alloy prepared by ball milling in different milling environments

摘要

The hydriding/dehydriding properties of the La_(1.8)Ca_(0.2)Mg_(14)Ni_3 alloy modified by mechanical ball milling for 20 h in different environment media, namely under argon, in toluene and in THF, respectively, have been investigated. XRD and SEM results show that the environment media affect the microstructure and surface morphology of the alloy noticeably. For the three environment media used, THF achieved the highest enhancement in hydriding/dehydriding properties. The effect of argon ranked the second and that of toluene the third. But the difference between the second and the third was very small. For the samples milled in THF, the amount of hydrogen absorbed reached 5.1 wt. percent within 300 s at 600 K and 4.2 wt. percent within 600 s at room temperature. The amount of hydrogen desorbed reached 5.05 wt. percent at 613 K. The remarkable improvement of the hydrogen storage properties of the ball-milled alloy in different environment media experimented is ascribed to the physical and chemical change of the alloy surface. Most probably are due to the appearance of the active sites and the electron donor-acceptor (EDA) complexes produced by the ball-milling process.