LAUSR

La-Sc-Ni based A2B7-type hydrogen storage alloys La1-xScxNi3.5 (x = 0.0~1.0) is prepared by an arc furnace method and maintained for a week in a sealed stainless steel tube at 1173 K. XRD and SEMEDS results show that the alloys are mainly consisted of LaNi5, La2Ni7 and minor LaNi phases. Under appropriate amount of Sc addition (x = 0.3~0.5), the (La, Sc)2Ni7 phase increases whereas the LaNi5 and LaNi phases decreases. Moreover, the further increase of Sc content results in appearance of Sc2Ni7 phase. The thermodynamic analyses show that the enthalpy change of La0.7Sc0.3Ni3.5-H2 is more close to -7.5 kcal mol -1 for the La-Mg-Ni-H2 system while the equilibrium absorption/desorption hydrogen pressure plateau of that is still higher than La-Mg-Ni systems, which indicate that the phase rule of Sc-containing alloy is different from Mg-containing alloy. Compared to pure La2Ni7 alloy, the maximum discharge capacity increases and the cycle stability improves by adding the right amount of Sc content (x = 0.3~0.5). Especially when x = 0.5, the cycle stability (S100) is up to 92.6% which is obviously superior to A2B7-type and AB5 type hydrogen storage alloys. We hope that our experimental results can develop the novel La-Sc-Ni-based hydrogen storage alloys by tuning their superlattice structures.