Hydrogen storage properties of Ml, _,Ca,Ni, pseudobinary intermetallic compounds

The hydrogen storage properties of the pseudobinary intermetallic compounds Ml, -.Ca,Ni, (where Ml is La-rich mischmetal and x varies from 0 to 0.9) were investigated over the temperature range of 25-80°C It was found in experiment that with increasing x in Ml,_,Ca,Ni, the incubation time for its first hydrogenation shortened, the first hydrogen absorption rate accelerated, the hysteresis lowered, and the dissociation pressure of the hydrides (25°C) increased when x < 0.3 but decreased in the range of x = 0.3 to 0.9. Considering the effect of the geometrical and electric factors, we deduced an equation for the dissociation pressure as a function of Ca content x. The equation agrees well with the test results. Owing to the lower cost and favourable properties of Ml,,,Ca,,,Ni,, a metal hydride container of 30 N m3 hydrogen capacity was designed and built to supply hydrogen for the hydrogen-gasoline hybrid fuel for an automobile engine.