Controllable hydrolysis performance of MgLi alloys and the hydrides.

Theoretically, hydrolysis of MgLi and MgH2-LiH composite can produce 9.6 and 17.5 wt.% hydrogen (water is not included in calculation), respectively. Ball milling method is commonly used to refine the particle size and thus may improve hydrolysis kinetics. However, Mg and Li will be easily agglomerated, which means directly ball-milling could not refine MgLi. In this work, we introduced 10 wt.% expanded graphite into ball milling process to synthesize refined MgLi alloy samples. Further study found that MgLi-10 wt.% expanded graphite can produce 966 mL/g hydrogen within 3 min in 0.5M MgCl2 solution. The MgLi hydrides were synthesized by the reactive ball milling under 3MPa H2 and their hydrolysis performance was investigated. Moreover, the sawed powder was milled in 3MPa H2 for 6 h and then hydrogenated in 3MPa H2 at 380 ℃; it can produce 1542 and 1773 mL/g (15.8 wt.%) hydrogen in 5 and 30 min with mild kinetics, respectively, and the activation energy of hydrolysis reaction is 24.6 kJ/mol in 1M MgCl2 solution. The findings here open a new avenue to the development of refined MgLi alloys and hydrides for hydrogen generation through controllable hydrolysis process.