Mechanically milled alanates as hydrogen storage materials

Hydrogen absorption kinetics of Na–Li–Al–H-based samples with different alkali/Al ratio prepared by mechanical milling was investigated. Na2LiAlH6 phase can be obtained even if the initial composition is out of stoichiometry. Rather higher hydrogen absorption rate was observed for the sample of alkali / Al = 2 sample compared to alkali / Al = 3 sample. This improved kinetics was interpreted by pressure dependence of initial reaction rate indicating the absorption process had changed to different rate-determining step.