Improvement of hydrogen storage kinetics in ball-milled magnesium doped with antimony

摘要

Kinetics and dynamics of hydrogen storage are studied in magnesium based alloys Mg-Sb-C doped with 5, 13.3 and 21 wt.% of antimony at temperatures between 275 degrees C and 350 degrees C. Carbon is added in order to facilitate the ball milling. MgH2 hydride is the principal hydrogen storage phase in all studied alloys. It is found that antimony (i) significantly improves the kinetics of hydrogen sorption compared to hydrogen sorption in pure Mg, and (ii) after long-term ball milling Sb attains the high sorption capacity c(max), which approaches the maximum theoretical value of the pure MgH2 hydride, c(th) = 7.7 wt.% H-2. The high value of c(max) remains unchanged in the whole temperature interval from 275 degrees C to 350 degrees C. At the temperature of 350 degrees C, the 90% of c(max) is (ab/de)sorbed typically within approximately 5 min starting with the second sorption cycle. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.