Superior hydrogen storage kinetics of Mg12YNi alloy with a long-period stacking ordered phase

Comparative investigations on the hydrogenation characteristics and hydrogen storage kinetics of melt-spun Mg10NiR (R = La, Nd and Sm) alloys

“…Such a kinetic property is much better than that for Mg 90 Ni 10 alloy and equivalent to that for Mg 80 Ni 10 Y 10 alloy [23]. This indicates that the contribution to the enhancement in the hydrogen absorptionedesorption kinetics is actually from both the rare earth metal hydrides and Mg 2 NiH 0.3 (or Mg 2 NiH 4 ) [10,23]. Fig.…”

“…It is found that the melt-spun Mg 10 a good catalytic effect on the hydrogen absorptionedesorption reactions in the MgÀH 2 system. However, the particle size of rare earth metal hydrides influences the hydrogen storage kinetics of MgeNieR alloys.…”

“…The LaH 3 or LaH 2 particles produced by hydrogenation of the crystalline La 2 Mg 17 should have a larger size than the NdH 2.61 and SmH 2 particles obtained by hydrogenation of the amorphous Mg 10 NiNd and Mg 10 NiSm alloys [10,12]. To obtain the sizes of rare earth metal hydrides in the activated Mg 10 NiLa, Mg 10 NiNd and Mg 10 NiSm samples, Rietveld refinements on the XRD profiles were performed and the refined parameters in the Lorentzian part of a pseudo-Voigt function were used as described elsewhere [10]. It is found that the average particle sizes of the rare earth metal hydrides in the activated Mg 10 NiLa, Mg 10 NiNd and Mg 10 NiSm samples are 37, 20 and 18 nm, respectively.…”

“…However, the worse kinetics is not related to the type of lanthanum hydrides (LaH 2 or LaH 3 ) even though the transformations between LaH 2 and LaH 3 occur during hydrogen absorption and desorption. Indeed, the catalytic effect of rare earth metal hydrides on the hydrogen absorptionedesorption kinetics of the MgÀH 2 system is related to the particle size of rare earth metal hydrides [10]. As shown in Fig.…”

“…Generally, the amorphous or nanostructured MgeNieR alloys prepared by melt-spinning have faster hydrogen absorptionedesorption kinetics than the as-cast alloys [17e20]. The improvement of absorption kinetics can be ascribed to the nano-sized particles of rare earth metal hydrides and Mg 2 Ni embedded in Mg matrix after activation; and the enhancement of desorption kinetics is attributed to the nano-sized particles of rare earth metal hydrides and Mg 2 NiH 4 embedded in MgH 2 matrix after hydrogenation [9,10,21,22]. Recently a study on the in situ synchrotron X-ray diffraction of hydrogenated Mg 80 Ni 10 Y 10 during its vacuum thermal decomposition indicated that the dehydrogenation of YH 3 to YH 2 was much slower than the dehydrogenation transformations of MgH 2 to Mg and Mg 2 NiH 4 to Mg 2 Ni; and accordingly metallic Mg, intermetallic Mg 2 Ni, hydrides YH 2 and YH 3 coexisted in the sample after hydrogen desorption at 473 K for 1 h [23].…”