Structure and electrochemical hydrogen storage characteristics of the as-cast and annealed La0.8-xSmxMg0.2Ni3.15Co0.2Al0.1Si0.05 (x=0-0.4) alloys

Cooperative effects of Sm and Mg on electrochemical performance of La–Mg–Ni-based alloys with A 2 B 7 - and A 5 B 19 -type super-stacking structure

“…The results prove that it is Sm that facilitates the refinement of the crystal grains in the co-substituted alloys. This is in accordance with the report of Li et al [22] who investigated La 0.8Àx Sm x Mg 0.2 Ni 3.15 Co 0.2 Al 0.1 Si 0.05 alloys and found that the FWHM values of the main diffraction peaks of both the as-cast and annealed alloys evidently grew with increasing amount of Sm. The refinement of the crystal grains may be related to the faster nuclear formation during the peritectic reaction with increasing amount of Sm substituting for La.…”

“…This is due to the contraction of the cell volumes as Sm and Mg substituting for La, which diminishes the room for hydrogen atoms during charging. Besides, it is found that the C max in our study is a little lower than that of the LaeMgeSmeNi alloys reported by some others [13,21,22]. This gap is considered to be related to both the components and the alloy types.…”

“…Therefore, the co-substitution method is supposed to be promising for A-site, but this has scarcely been studied yet. Samarium (Sm) is not only an abundant and cheap element but is also used to improve the electrochemical performance of hydrogen storage alloys [13,21,22]. Rui et al [13] improved the HRD and the cycling stability of the La 1.3 CaMg 0.7 Ni 9 alloy using Sm to substitute for La, but the maximum discharge capacity of the alloys was decreased.…”

“…Rui et al [13] improved the HRD and the cycling stability of the La 1.3 CaMg 0.7 Ni 9 alloy using Sm to substitute for La, but the maximum discharge capacity of the alloys was decreased. Zhang et al [21] and Li et al [22] [28]. However, when the content of Mg is too high, the LaMg 2 Ni 9 phase or other Mg-rich phases tend to form, which jeopardizes the discharge capacity as well as the cycling stability of the alloys [2].…”

Effect of Sm on hydrogen storage performance of La–Sm–Mg–Ni alloys

“…Similar result was reported as well. 23 General speaking, the pulverisation and corrosion during the charging-discharging cycles are a group 1; b group 2 2 Curves (PCT) of alloys at 303 K two main critical factors that led to the degradation of discharge capacity. According to former studies, 28 the anti-pulverisation capability is relative to several factors, such as the composition, homogeneity, cell volume, toughness, hydrogen absorption capacity, crystal size, corrosion resistance of the alloy and so on.…”