Controllable Hydrolysis Performance of MgLi Alloys and Their Hydrides

Theoretically, the hydrolysis of MgLi and MgH₂ -LiH can produce 9.6 and 17.5 wt.% hydrogen (water is not included in the calculation), respectively. The 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 that direct ball-milling could not refine MgLi. In this work, we introduced 10 wt.% expanded graphite into the ball-milling process to synthesize refined MgLi alloy samples. Further studies showed that MgLi-10 wt.% expanded graphite can produce 966 mL/g hydrogen within 3 min in 0.5 M MgCl₂ solution. The MgLi hydrides were synthesized by reactive ball milling under 3 MPa H₂ and their hydrolysis performance was investigated. Moreover, the sawed powder was milled in 3 MPa H₂ for 6 h and then hydrogenated in 3 MPa H₂ at 380 °C; 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 the hydrolysis reaction is 24.6 kJ/mol in 1 M MgCl₂ solution. The findings here open a new avenue to the development of refined MgLi alloys and hydrides for hydrogen generation through a controllable hydrolysis process.