| Title |
Hydrogen Uptake and Release Characteristics of Mg-xTaF5-xVCl3 (x=1.25, 2.5, and 5) |
| Authors |
(Myoung Youp Song); (Young Jun Kwak) |
| DOI |
https://doi.org/10.3365/KJMM.2018.56.8.611 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
hydrogen absorbing materials; mechanical milling; scanning electron microscopy (SEM); X-ray diffraction; TaF5 and VCl3 addition |
| Abstract |
TaF5 and VCl3 were chosen as additives to enhance the hydrogen uptake and release rates of Mg. The total content of the additives was not more than 10 wt% since too high content reduces the fraction of Mg and thus the hydrogen storage capacity of the alloys. Samples with compositions of Mg-x wt% TaF5-x wt% VCl3 (x=1.25, 2.5, and 5) were prepared by reactive mechanical grinding. The temperatures at which the asmilled Mg-xTaF5-xVCl3 (x=1.25, 2.5, and 5) began to release hydrogen quite rapidly were 538, 613, and 642 K, respectively. Activation of the samples was not needed. In the first cycle (n=1), Mg-2.5TaF5-2.5VCl3 had quite a high effective hydrogen storage capacity (the amount of hydrogen absorbed for 60 min) of 5.86 wt%. Among the three samples, Mg-1.25TaF5-1.25VCl3 had the best hydrogen release properties. In n=4, Mg-1.25TaF5- 1.25VCl3 had the largest quantity of hydrogen released for 60 min at 593 K in 1.0 bar H2, releasing 0.23 wt% H for 5 min, 0.34 wt% H for 10 min, and 3.31 wt% H for 60 min. After hydrogen uptake-release cycling, Mg- 1.25TaF5-1.25VCl3 had the smallest particle size. In n=5, Mg-1.25TaF5-1.25VCl3 released 2.01 wt% H for 5 min, 3.78 wt% H for 10 min, and 4.89 wt% H for 60 min at 623 K in 1.0 bar H2.(Received May 30, 2018; Accepted June 15, 2018) |